city and borough of sitka, alaska filtration evaluation for critical secondary water source final...

C I T Y A N D B O R O U G H O F S I T K A , A L A S K A

FILTRATION EVALUATION FOR CRITICAL SECONDARY WATER SOURCE

FINAL REPORT

APRIL 2018

Prepared for:

City and Borough of Sitka

Prepared by:

CRW Engineering Group, LLC3940 Arctic Blvd. Suite 300

Anchorage, AK 99503

ContactPete Bellezza, PE

[email protected] Arctic Blvd., Suite 300 Anchorage, AK 99503p (907)562.3252 | f (907)561.2273 | www.crweng.com

January 25, 2018

CITY AND BOROUGH OF SITKAPublic Works DepartmentRequest for Qualifications Establishment of Professional Services Roster

ServicesCivil EngineeringElectrical EngineeringMechanical EngineeringStructural Engineering

UPDATEDAPRIL 19, 2019

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLCFinal Report - UPDATE Page i April 2019

Table of Contents

1. Executive Summary ..........................................................................................................1

1.1 Conclusions.......................................................................................................................................11.2 Recommendations............................................................................................................................2

2. Introduction, Background, Design Criteria ........................................................................4

2.1 Introduction and Background...........................................................................................................4

2.1.1 Previous Filtration Experience .....................................................................................................................5

2.2 Design Flow.......................................................................................................................................62.3 Water Source & Quality....................................................................................................................6

2.3.1 Sawmill Creek...............................................................................................................................................62.3.2 Indian River ..................................................................................................................................................7

3. Regulatory Requirements ...............................................................................................10

3.1 Filtration Avoidance........................................................................................................................10

3.1.1 Limited Alternative to Filtration.................................................................................................................11

3.2 Conventional and Direct Filtration..................................................................................................113.3 Membrane Filtration ......................................................................................................................123.4 Backwash Disposal..........................................................................................................................12

3.4.1 Filter Backwash Recycling Rule (FBRR).......................................................................................................12

4. Pre-Treatment, Filtration, and Backwash Disposal Alternatives ......................................13

4.1 Dissolved Air Flotation (DAF) and Granular Media Filtration .........................................................134.2 Granular Media Filtration ...............................................................................................................13

4.2.1 Process Description....................................................................................................................................134.2.2 Backwash ...................................................................................................................................................144.2.3 Startup, Shutdown, and Standby Considerations ......................................................................................144.2.4 Advantages/Disadvantages........................................................................................................................14

4.3 Membrane Filtration ......................................................................................................................15

4.3.1 Process Description....................................................................................................................................154.3.2 Backwash ...................................................................................................................................................154.3.3 Startup, Shutdown, and Standby Considerations ......................................................................................164.3.4 Advantages/Disadvantages........................................................................................................................16

4.4 Backwash Disposal..........................................................................................................................17

4.4.1 Disposal to Sanitary Sewer.........................................................................................................................17

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLCFinal Report - UPDATE Page ii April 2019

4.4.2 Recycle .......................................................................................................................................................174.4.3 Marine or Freshwater Outfall Discharge....................................................................................................18

5. Site and Source Alternatives ...........................................................................................19

5.1 Sawmill Creek – Adjacent to UV Facility .........................................................................................19

5.1.1 Description.................................................................................................................................................195.1.2 Land Requirements ....................................................................................................................................225.1.3 Potential Construction Problems ...............................................................................................................225.1.4 Advantages/Disadvantages........................................................................................................................22

5.2 Sawmill Creek – At Pulp Mill Filters ................................................................................................23


5.3 Indian River.....................................................................................................................................26


6. Selection of an Alternative .............................................................................................29

6.1 Cost Estimates ................................................................................................................................29

6.1.1 Capital Costs...............................................................................................................................................296.1.2 O&M Costs .................................................................................................................................................30

6.2 Non-Monetary Evaluation ..............................................................................................................30

6.2.1 Location Alternatives .................................................................................................................................316.2.2 Treatment Technology Alternatives...........................................................................................................31

7. Conclusion and Recommendations .................................................................................32

7.1 Conclusion ......................................................................................................................................327.2 Recommendations..........................................................................................................................33

List of Tables

Table 1 - Design Flow Criteria .......................................................................................................................6Table 2 - Sawmill Creek Water Quality .........................................................................................................7Table 3 - Indian River Water Quality.............................................................................................................8Table 4 – Required Pathogen Removal.......................................................................................................10Table 5 – Conventional and Direct Filtration Pathogen Removal Credits...................................................11Table 6 - Typical Backwash Water Quality..................................................................................................17

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLCFinal Report - UPDATE Page iii April 2019

Table 7 – Capital Costs................................................................................................................................29Table 8 – Daily O&M Costs .........................................................................................................................30Table 9 - Annual O&M Costs.......................................................................................................................30Table 10 - Location Non-Monetary Scores .................................................................................................31Table 11 - Treatment Non-Monetary Scores ..............................................................................................31

List of Photos

Photo 1 - CBS Water System General Locations ...........................................................................................5Photo 2 - Sawmill Creek Canyon...................................................................................................................6Photo 3 - Indian River Before & During Flood (August 2014, taken less than a week apart) .......................8Photo 4 - DAF Package Plant.......................................................................................................................13Photo 5 - Adsorption Clarifier System ........................................................................................................14Photo 6 - Package Membrane System........................................................................................................15Photo 7 - Equalization Basin With Floating Decant ....................................................................................18Photo 8 – Sawmill Creek Site - Lot 17 Adjacent to UV Facility....................................................................19Photo 9 - Sawmill Creek Site – Lot 19 Adjacent to UV Facility....................................................................20Photo 10 - Pulp Mill Filter Basins ................................................................................................................23Photo 11 - Potential Intake Location in Sawmill Creek...............................................................................24Photo 12 - Existing Perforated Pipe Intake.................................................................................................27

List of Figures

Figure 1 – Equipment Layout and Plant SizeFigure 2 – Sawmill Creek Lot 17 – Granular Media FiltrationFigure 2A – Sawmill Creek Lot 19 – Granular Media FiltrationFigure 3 – Sawmill Creek Lot 17 – Membrane Filtration Figure 3A – Sawmill Creek Lot 19 – Membrane FiltrationFigure 4 – Sawmill Creek at Pulp Mill Filters – Granular Media FiltrationFigure 5 – Sawmill Creek at Pulp Mill Filters – Membrane FiltrationFigure 6 – Indian River – Granular Media FiltrationFigure 7 – Indian River – Membrane Filtration

List of Appendices

Appendix A – Water Quality DataAppendix B – Correspondence and Trip ReportAppendix C – Vendor DataAppendix D – Detailed Cost Information (Updated in April 2019)Appendix E – Geotechnical Reports

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLCFinal Report - UPDATE Page iv April 2019

Acronyms and Abbreviations

% percentageADEC Alaska Department of Environmental ConservationADF&G Alaska Department of Fish & GameADOT Alaska Department of Transportation and Public FacilitiesAPDES Alaska Pollutant Discharge Elimination SystemBLWTP Blue Lake Water Treatment PlantCBS City and Borough of SitkaCCF Corrosion Control FacilityCFE Combined Filter Effluentcfs Cubic feet per secondCIP Clean In PlaceCRW CRW Engineering Group, LLCCT Chlorine Concentration * TimeDAF Dissolved Air FlotationEFM Enhanced Flux MaintenanceFBRR Filter Backwash Recycle RuleEPA Environmental Protection AgencyFEMA Federal Emergency Management AgencyFERC Federal Energy Regulatory Commissionft feetFTW Filter to WasteF degree Fahrenheitgpm gallons per minuteGPIP Gary Paxton Industrial ParkIFE Individual Filter EffluentLAF Limited Alternative to FiltrationNTU Nephelometric Turbidity UnitskW kilowatt

MGD Million gallons per dayO&M operation and maintenance PWS Public Water SystemROW right-of-waySDC Engineering Services During ConstructionSDWA Safe Drinking Water ActSWTR Surface Water Treatment RuleTWUA Temporary Water Use AuthorizationUV UltravioletWTP Water Treatment PlantWWTP Wastewater Treatment Plant

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLCFinal Report - UPDATE Page v April 2019

References

Dedicated Water Line Report. CH2M. January 2018.

Indian River Evaluation. CRW Engineering Group, LLC. December 2017.

Membrane Filtration Guidance Manual. EPA. November 2005.

Temporary Filtration Evaluation Technical Memorandum. CH2M HILL. May 2012.

Temporary Filtration Project Report. CH2M HILL. May 2013.

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLCFinal Report - UPDATE Page 1 April 2019

1. Executive Summary

The City and Borough of Sitka (CBS) currently obtains water from Blue Lake for its municipal water supply. Water flows by gravity from an intake structure in the lake through rock tunnels and a penstock to the Blue Lake Water Treatment Plant (BLWTP). A 24-inch line from the penstock supplies water to the BLWTP with the rest of the water flowing to the Blue Lake hydropower facility. The intake, rock tunnels, penstocks and associated infrastructure are operated by the CBS Electric Department as part of the Blue Lake Hydroelectric Project (Blue Lake Hydro). Blue Lake Hydro is regulated by the Federal Energy Regulatory Commission (FERC), which requires periodic inspection and maintenance of regulated infrastructure to ensure continued safe operation. Routine inspection and maintenance of the intake gate, rock tunnels, penstocks and associated infrastructure require dewatering of these areas and outages of the penstock that supplies raw water to BLWTP.

CBS currently operates under a filtration avoidance waiver for drinking water treatment, one of about 12 systems in the Pacific Northwest and 70 systems nationwide operating under this regulatory framework. The waiver has strict turbidity requirements. Exceeding the maximum turbidity levels more than two times in a 12 month period or five times in a 120 month (ten-year) period would trigger the requirement for providing filtration. CBS has experienced 4 turbidity events in the past 4 years, with the most recent in the fall of 2018. One additional turbidity event beyond the allowable exceedances will require CBS to pursue full time filtration.

This report provides a detailed conceptual analysis of filtration alternatives on two potential water sources for supplying water to the community during penstock outages and high turbidity events. This work was recommended in the January 2018 Dedicated Water Supply Report, which evaluated dedicated water supply sources for CBS. This report evaluated the feasibility of two general options: implementing filtration at the existing Indian River water source, or developing Sawmill Creek, downstream of Blue Lake, as a new source which would require filtration. The existing Blue Lake source and UV Facility would remain the primary supply, and the filtration plant would be used on an intermittent basis during penstock outages or high turbidity events. If the filtration avoidance waiver was revoked, the filtration plant could be used full time. This report also evaluated a number of pre-treatment options, including dissolved air flotation (DAF), up-flow clarification, and flocculation and settling. Filtration alternatives include granular media and microfiltration membrane systems, as recommended by the Dedicated Water Supply Report.

This report was partially updated in April 2019 to reflect the results of geotechnical studies performed in the latter half of 2018 and the resultant impact on the overall recommended site selection.

1.1 Conclusions

Based on the evaluation of capital and operating costs and non-monetary factors, an intermittent granular filtration plant treating Sawmill Creek water and located adjacent to the existing Ultraviolet (UV) Facility is the recommended alternative for operation during penstock outages and periods of high turbidity water when the UV Facility cannot be used. The primary advantages of this option are lower capital and operational treatment costs due to higher quality source water than Indian River for more affordable treatment options. Should the plant need to be used full time in the future, this option will provide a lower annual operating cost than other options.

The advantages and disadvantages of the recommended alternative are summarized below.


Advantages: Generally high quality source water with adequate existing water rights. The good water quality has

been confirmed through extensive water quality testing throughout 2018.

Good proximity to existing infrastructure (power, sewer, raw water, finished water).

Generally known and good geotechnical conditions for construction, which was confirmed with the Lot 17 geotechnical evaluation in 2018.

Available property with no need for demolition of existing infrastructure, and associated risk with selective demolition.

Relatively small footprint requirements.

Multiple trains allow for flexibility in operating loading rates based on flow demands and water quality.

Reduced backwash volumes compared to membrane filtration.

No operator involvement in monitoring the system when it is offline.

Disadvantages: Difficult to construct intake and pipeline for conveying water during penstock outages.

Limited ability to treat and dispose of large backwash water volumes, which may be mitigated with backwash recycling or ocean discharge.

Does not provide a fully redundant water source.

Coagulant dosing will be critical to successful filter operation. High quality source water may require higher coagulant doses.

Seasoned operator experience and judgment will be needed to optimize treatment process. Vendor or engineering support during the first few operational periods would help provide operator training.

Additional water quality data from Sawmill Creek is needed to verify selection of the recommended pre-treatment process. Sampling was conducted throughout 2018, and benchtop testing of treatment chemicals is underway in spring 2019.

Should the filtration avoidance waiver be revoked, the recommended filtration process could be used full time treating water from either Blue Lake or Sawmill Creek.

1.2 Recommendations

The intake construction in Sawmill Creek has the most uncertainty of the various components of the project. To help alleviate some of this uncertainty, survey and geotechnical work should be completed as soon as practical. To move forward with the selected alternative, the following activities should be pursued.

Continue collection of water quality data, especially during high flow and poor water quality conditions to help identify the worst case water that will need to be treated.

o Started in 2018, continuing into 2019.

Work with ADEC to determine sampling required to establish a new source.

o Sampling is underway.


Perform a geotechnical investigation that includes drilling rock cores to locate the intake. This work will allow for early site development and preliminary permitting activities, as well as facilitate the design of the intake and filtration building foundation.

o Geotechnical evaluations were completed in the second half of 2018.

Perform a detailed survey of the intake location and site.

Evaluate construction strategies to quickly and cost-effectively complete the project.

Once the equipment supplier is selected, move forward with design, permitting, and construction.

If the selected alternative requires a crossing of Sawmill Creek on the existing utility bridge, an evaluation of options to replace or augment the bridge should be performed.


2. Introduction, Background, Design Criteria

2.1 Introduction and Background

The City and Borough of Sitka (CBS) obtains water from Blue Lake for its municipal water supply. Water flows by gravity from an intake structure in the lake through rock tunnels and a penstock to the Blue Lake Water Treatment Plant (BLWTP). A 24-inch line from the penstock supplies water to the BLWTP with the rest of the water flowing to the Blue Lake hydropower facility. Blue Lake water is very high quality, and not required to be filtered. Disinfection is accomplished with the addition of chlorine and irradiation with UV light, in compliance with the CBS filtration avoidance waiver.

The intake, rock tunnels, penstocks and associated infrastructure are operated by the CBS Electric Department as part of the Blue Lake Hydroelectric Project (Blue Lake Hydro). Blue Lake Hydro is regulated by the Federal Energy Regulatory Commission (FERC), which requires periodic inspection and maintenance of regulated infrastructure to ensure continued safe operation. Routine inspection and maintenance of the intake gate, rock tunnels, penstocks and associated infrastructure require dewatering of these areas and outages of the penstock that supplies raw water to BLWTP.

The filtration avoidance waiver has a strict maximum turbidity requirement of 5.0 NTU. Exceeding the maximum turbidity level more than two times in a 12 month period or five times in a 120 month (ten-year) period would trigger the requirement for providing filtration. CBS has experienced 4 turbidity events in the past 4 years. One additional turbidity event beyond the allowable exceedances will require CBS to pursue full time filtration. When the Blue Lake water meets the filtration avoidance criteria, operation of the existing system provides plentiful, high-quality, affordable drinking water to CBS, and is the preferred treatment option.

CBS has evaluated many options to provide water during penstock outages and emergency shut-down’s. Most of these options have revolved around providing a dedicated intake and water line to connect to the existing water treatment system. Several options have evaluated developing a new water source or utilizing historic sources, most of which require filtration. Since CBS has experienced several turbidity events in recent years, options to supply the community during penstock outages that also include filtration that could be used for turbidity events are evaluated in more detail in this report.

Filtration would be used intermittently; only when the existing surface water supply is unavailable, either due to high turbidity in Blue Lake, maintenance-related shutdowns of the hydropower penstock, and penstock emergencies. High turbidity events are caused by significant storm events in the water shed and sudden increases of flow through the hydropower facility due to hydropower facility operation. Penstock shutdowns involve inspections and maintenance that are performed by the Sitka Electrical Department every five years, or emergencies that require immediate shutdown of the equipment.

This report evaluated the feasibility of two general options: implementing filtration at the existing Indian River water source, or developing Sawmill Creek, downstream of Blue Lake, as a new source which would require filtration. This report also evaluated a number of pre-treatment options, including dissolved air flotation (DAF), up-flow clarification, and flocculation and settling. Filtration alternatives include granular media and microfiltration membrane systems, as recommended by the Dedicated Water Supply Report. Photo 1 shows an overview of the CBS water source locations and facilities described in this report.


Photo 1 - CBS Water System General Locations1:Blue Lake, 2:UV Facility, 3:Sawmill Creek Source, 4:Indian River Source

The CBS water system has a 1.2-MG water storage tank as the primary storage in the system which is augmented by two additional tanks; Harbor Mountain (800,000 gallons); Whitcomb (1,000,000 gallons). This storage is inadequate to meet the system demands during a system outage. If penstock outages occurred during minimum flow periods, up to 14-million gallons of storage would be needed to allow a 5-day shutdown of the penstock. This is an impractical amount of storage for normal system operation, would have a cost of $40 to 50 million, and does not provide adequate storage for high turbidity events of unknown duration.

2.1.1 Previous Filtration ExperienceSitka has prior experience with potable water filtration. Indian River was used as a temporary water supply during the Blue Lake dam raising project in 2014. Water was filtered through membrane filters before entering the distribution system with no pre-treatment. Limited water quality data collected during the planning portion of the work indicated that direct filtration would provide adequate treatment. During the project, Sitka experienced a number of large storm events, each causing significantly worse raw water quality than expected based on the sampling in the planning period. The filter membranes adequately treated these high turbidities experienced during the storm events, but were unable to remove the large amounts of total and dissolved organic carbon from the river leading to high color, high chlorine demand, and high levels of disinfection byproducts in the treated water. The filters required more chemical cleaning than anticipated due to the unexpected turbidity and organics levels in the raw water. Based on this experience, the equipment provider for the rented microfiltration system recommended that any permanent installation on this source include pretreatment.

During the Blue Lake Dam raising project, the water treatment equipment was rented due to the temporary nature of the project, as this was more cost effective than purchasing the equipment. While the project provided water that met the needs of CBS at the time, the plant was difficult to operate, requiring CBS to retain a temporary full-time operator dedicated to the temporary plant. The temporary nature of the plant drove design decisions that would not be applicable for a permanent installation. During the design of the temporary filtration plant there was discussion about purchasing the membrane filtration units. The cost to purchase the units did not include any of the pumping,


chemical delivery, chlorine contact tanks, or control system equipment that would be required for a permanent installation, which made the cost seem lower than the total project cost would be.

2.2 Design Flow

The UV Disinfection facility was constructed in 2015, and sized to meet current and future demands. The filtration facility will be sized to match the same capacity, as summarized in Table 1. The CBS water treatment flow rates are based on the use in the system which varies daily and seasonally. The water treatment equipment must be able to ramp up and down production quickly to meet the use in the system because the water system has limited storage and can only supply water for several hours without impacts to system users.

Table 1 - Design Flow Criteria

Design Flow

Peak Hour/Future Flow 6.0 MGD

Average Summer Flow 4.0 MGD

Average Winter Flow 3.0 MGD

Minimum Flow 1.8 MGD

2.3 Water Source & Quality

Two water sources are available for an intermittent filtration facility, Sawmill Creek and Indian River.

2.3.1 Sawmill CreekSawmill Creek is located on the east end of Sitka (diamond 3 in Photo 1). Blue Lake is the headwater for Sawmill Creek, which discharges to Sawmill Cove. Flows in Sawmill Creek are largely controlled by the hydroelectric facility’s release of water from a side line connected to the penstock (commonly referred to as the “fish valve”). The fish valve release provides the minimum in-stream flow requirement of 70 cfs (approximately 31,400 gpm) April 15-June 30 and 50 cfs (approximately 22,000 gpm) the rest of the year for the fishery, which thereby stabilizes the river from large variations in turbidity or flow. The fish valve is sized to provide 70 cfs into Sawmill Creek at low levels in Blue Lake. During the high release periods, the valve does not have the capacity to meet both the fish flow requirements and municipal needs.

During penstock outages, the fish valve is also out of service for inspection and maintenance. In this case, the electric utility will open the Howell Bunger valve at the bottom of the dam to provide in stream flows. The valve has not been used in some time, and should be tested prior to relying fully on this option.

If Sawmill Creek was utilized as a water source, the hydroelectric facility would utilize the fish valve and Howell-Bunger valve to allow additional water to flow in the river to meet fishery-required in-

Photo 2 - Sawmill Creek Canyon


stream flows and municipal needs. Flow and water quality in Sawmill Creek can also be impacted by storm events in the watershed, water spilling over the top of the dam, or water released from the Howell-Bunger valve in the bottom of the dam.

A new water intake in Sawmill Creek would be located upstream of tidal influences and the hydropower facility afterbay. The highest tide in the area is 13 feet above the mean sea level (MSL). Photo 1 shows the potential intake location in Sawmill Creek. Details of the intake configuration are discussed in Section 5.

Limited water quality data is available for Sawmill Creek because sampling is not required. CBS is currently collecting water quality data to determine average and maximum values of important parameters needed for sizing water treatment equipment and detailing the process selection. Preliminary water quality results are included in Appendix A and summarized in Table 2.

2.3.1.1 Sawmill Creek Water RightsCBS holds adequate water rights in Blue Lake to meet its current and future water system needs. To utilize the water downstream of Blue Lake, a Temporary Water Use Authorization (TWUA) would be required from the Department of Natural Resources (DNR). The application must be completed in advance of any water withdraw and is good for a period of five years. The CBS electric department controls the flow in Sawmill Creek to maintain in-stream flow requirements for returning salmonid species, as well as providing water to the CBS water system and a fish hatchery.

Table 2 - Sawmill Creek Water Quality

Parameter Average Minimum Maximum

Turbidity (NTU)1 0.62 0.44 0.98

Total Organic Carbon2 (mg/L) 0.91 0.73 1.10

Total Dissolved Solids2 (mg/L) 54.5 41.0 68.0

Total Suspended Solids2 (mg/L) 1.9 0.8 3.0

1. 58 samples collected January - March 2018.2. Three samples collected monthly January - March 2018

The raw water quality from Sawmill Creek is generally very similar to Blue Lake with low turbidity, organic carbon, and solids. Observations from CBS staff indicate that during storm events or when the dam is spilling the water quality in Sawmill Creek changes, with increases in turbidity and solids. There are not monitoring requirements for Sawmill Creek so analytical samples have not been collected. Sampling is currently underway to determine the nature of the water quality changes.

2.3.2 Indian RiverIndian River was the CBS water source until 1986 when the variable water quality and forthcoming filtration regulations compelled CBS to switch to Blue Lake as the primary water source. The existing intake is located on the west channel of a small island. The Indian River Water Treatment Plant (IRWTP) consists of a shallow underdrain/intake system under Indian River that feeds a small sand filter. Water from the bottom of the sand filter is pumped to the distribution system after chlorine injection. The filter cannot be backwashed or cleaned effectively, which reduces the amount of flow

City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLC Final Report ‐ UPDATE Page 8 April 2019

that can be produced by the filter. This filter system does not receive Giardia removal credit. Several of the existing pumps have failed and have not been repaired or replaced.

Indian River is a dynamic river, and its water quality fluctuates seasonally and with storm events. Water quality sampling was performed prior to the temporary filtration project in 2013 summarized in Table 3.

Table 3 ‐ Indian River Water Quality

Parameter Average Minimum Maximum

Turbidity (NTU)1 1.35 0.25 12.83

Total Organic Carbon2 (mg/L) 2.24 0.77 6.2

Total Dissolved Solids2 (mg/L) 51.6 23.0 64.0

Total Suspended Solids2 (mg/L) 0.87 0 5.2

1. 100 samples July‐December 2013. 2. 6 samples collected July‐December 2013. Total Suspended Solids were 5 non‐detect, and one sample at 5.2 mg/L. 3. August 2014 temporary filtration plant had samples with more than 100 NTU

A new water intake in Indian River would be located in the vicinity of the old intake and would draw water from the western river channel. During the temporary filtration project in August 2014, significant flooding occurred, which resulted in raw water turbidities of over 100 NTU and very high levels of organics. While this variation was unexpected based on seasonal storm sampling in preparation for the Indian River project, it shows the highly irregular nature of Indian River.

Photo 3 ‐ Indian River Before & During Flood (August 2014, taken less than a week apart)

In addition to the water quality variability in Indian River, the reach where the intake would be located is dynamic where both erosion and deposition are active. There are high sediment and debris load which make channel position difficult to predict and maintain, complicating intake design. During low flow periods, most of the flow may be in the eastern channel, and depending on the intake design, it may not be possible to divert the needed system demand.

2.3.2.1 Indian River Water Rights CBS maintains a 2.5 MGD (approximately 3.9 cfs) water right in Indian River. A larger water right would need to be secured to meet the required system demand of 6 MGD (9.3 cfs). Seasonal flows can range from 12 to 1,300 cfs. Water flow in Indian River is heavily influenced by precipitation


events in the watershed. The river bed changes significantly during flood events, so an intake would need to be located and designed to capture flow through the alluvial portion of the river.

A TWUA can be requested for Indian River. As part of the request CBS and the Department of National Resources will have to demonstrate to the Alaska Department of Fish and Game (ADF&G) that the diversion would not violate ADF&G’s instream flow rights for the river and the water right rights to operate the hatchery at the Sitka Sound Science Center. Should the flow drop below the ADF&G rights, the CBS TWUA would be shut down.


3. Regulatory Requirements

The Environmental Protection Agency (EPA) issued the Surface Water Treatment Rule (SWTR) in 1989, requiring all public water treatment facilities to filter and disinfect surface water sources unless filtration avoidance criteria is met. Enhanced SWTR’s have been issued since 1989 and are designed to protect against water-borne pathogens including viruses, giardia, and cryptosporidium. They were developed based on research that some pathogens like Cryptosporidium are resistant to inactivation by chlorine. Each pathogen category has individual removal or inactivation requirements depending on the source water quality and the treatment process. In addition, the SWTRs outline treatment and monitoring requirements including disinfectant residuals and turbidity limits.

Table 4 shows the required pathogen removal or inactivation for all types of systems. Sitka currently meets these requirements through chlorine and UV disinfection, utilizing a filtration avoidance waiver.

Table 4 – Required Pathogen Removal

Giardia Virus Cryptosporidium

Filtration Avoidance Required Inactivation 3-log 4-log 3-log

Filtration Required Removal/Inactivation 3-log 4-log 2-log

For the purposes of this report, it is assumed that the UV facility will be offline while the filtration plant is online. Chlorine injection is required to maintain a residual in the distribution system for any treatment technology, and the ADEC frequently requires at least a 0.5-log Giardia inactivation by chlorine, even in systems with documented high removal/inactivation. Filtration equipment can readily provide 2.5-log Giardia removal. The combination of filtration and chlorination meets the required removal/inactivation of pathogens and additional treatment from UV is not advantageous. Operation of the UV equipment at the same time as the filter equipment would increase the operation and maintenance cost unnecessarily.

3.1 Filtration Avoidance

CBS is currently operating under a filtration avoidance waiver by meeting source water quality, site-specific criteria, and utilizing a combination of chlorine and UV disinfection. CBS is one of 70 utilities in the country utilizing filtration avoidance, out of approximately 160,000 water utilities. Maintaining the filtration avoidance waiver is the least cost option for providing high quality water to CBS. Developing a secondary source to use when water quality does not meet the stringent filtration avoidance criteria would allow CBS to selectively utilize the treatment needed for the current source water conditions.

For filtration avoidance, source raw water must have no greater than 20 fecal coliforms per 100 mL sample and turbidity levels must not exceed 5 NTU more than two times in a 12 month period or five times in a 120 month period. If either of these criteria are not met, filtration must be installed within 18 months of the exceedance event. At the time of this report, Sitka has experienced 4 turbidity events in the past 4 years. Two turbidity events in one year, or one more event in the next 6 will put the filtration avoidance in jeopardy and may require the implementation of a full-time filtration system.

One strategy to maintain the filtration avoidance is to develop a secondary water supply for use during high turbidity events. When this approach was discussed with Scott Forgue, PE of the Alaska Department of Environmental Conservation (ADEC) Drinking Water program, he indicated that construction of a filtration facility at Indian River or Sawmill Creek would provide this secondary source. This would allow


Sitka to have two sources – a filtration source, and a filtration avoidance source. Notes from these discussions are included in Appendix B.

3.1.1 Limited Alternative to FiltrationThe Safe Drinking Water Act provides provision for unfiltered systems called a Limited Alternative to Filtration (LAF) that allows a utility with very strict watershed control to consider alternative disinfection strategies. Washington is the only state known to have developed guidelines for a LAF, which allows for more coliforms to be present in the raw water than the filtration avoidance waiver provided one additional log-removal is provided and a third disinfectant is utilized. The LAF does not modify the 5 NTU maximum turbidity requirement of the filtration avoidance criteria. Based on conversation with Scott Forgue, PE of ADEC, if Alaska were to develop regulations allowing a LAF, it would likely use the Washington regulations as a guideline and would maintain the 5 NTU maximum turbidity standards. If a LAF was pursued for CBS, the high turbidity events in Blue Lake would continue to put the filtration avoidance at risk, so this regulatory pathway was not considered further for CBS.

3.2 Conventional and Direct Filtration

Conventional filtration consists of coagulation, flocculation and settling prior to filtration. Direct filtration does not include flocculation or settling, and consists only of coagulant injection to aid coagulation before filtration. Filter media can be comprised of granular media or membranes; however, cryptosporidium removal requirements for membrane filtration is dependent on individual system testing, described in Section 3.3.

Turbidity requirements for filtered water systems under the SWTRs consist of monitoring combined filter effluent (CFE) levels and individual filter effluent (IFE) levels. CFE levels must be no greater than 0.3 NTU. If this threshold is exceeded, reporting of IFE readings and filter performance assessment actions will be required. The filter performance assessments are based on the severity of the exceedance of the CFE reading, and includes detailed evaluation of the cause of the high turbidity, filter profiling, and filter self-assessments.

Table 5 shows filtration removal credits and the remaining required inactivation by chlorine disinfection. Disinfection removal varies depending on residual chlorine concentration, water temperature, pH, and the contact time between the water and disinfectant.

Table 5 – Conventional and Direct Filtration Pathogen Removal Credits


Giardia Virus CryptosporidiumRemoval credit 2.5-log 2.0-log 3.0-logConventional

Filtration Disinfection required1 0.5-log 2.0-log n/a2

Removal credit 2.0-log 1.0-log 2.5-logDirect filtration

Disinfection required1 1.0-log 3.0-log n/a2

Removal credit 3.0-log n/a 3.0-log+Microfiltration

Disinfection required1 n/a 4.0-log n/a2

1. Required disinfection assumed to be via chlorine.2. Cryptosporidium is very resistant to chlorine inactivation, and credit cannot be achieved by chlorine disinfection.

3.3 Membrane Filtration

Membrane filters can be used in conventional or direct filtration systems. This type of filter consists of small tube-like perforated fibers which capture particulates larger than one micrometer (0.001 millimeter or 3.9 x 10-5 inch) as water is passed through them. In 2005, the EPA published the Membrane Filtration Guidance Manual, which provides specific guidelines for determining the effectiveness of membranes for Cryptosporidium removal through testing. Each membrane product undergoes challenge testing by the manufacturer to determine the maximum removal credits it is eligible to receive.

Once a membrane system is installed, direct or indirect integrity testing is required to verify that adequate particulate removal is occurring. Direct testing requires the system to be taken offline at least once per day, and pressurized with air to determine if there are any breaks in the membrane fibers. Continuous indirect integrity testing consists of continuous monitoring of the filtered water for a parameter that should be removed by the filtration process—generally turbidity. This process provides verification of the removal credits received through challenge testing. Turbidity requirements to verify Cryptosporidium removal for membrane filters require that IFE must measure below 0.15 NTU.

3.4 Backwash Disposal

Backwash disposal is regulated by ADEC wastewater regulations. The specific regulation in effect depends on the location of the backwash disposal. Most frequently Alaska Pollutant Discharge Elimination System (APDES) permits govern disposal into any waterbody. Solid waste regulations govern the disposal of solids into landfills or biosolids receiving areas.

3.4.1 Filter Backwash Recycling Rule (FBRR)Many filtration facilities recycle some or all of the backwash to the head of the plant to reduce the amount of backwash that must be disposed of. The Filter Backwash Recycling Rule governs recycle practice with the aim of preventing pathogens from passing through systems into drinking water because backwash water may contain high concentrations of pathogens. The main components of the FBRR are:

The recycle return location must be upstream of all treatment processes.

The system must keep record of and report the quantity and quality of water recycled.


4. Pre-Treatment, Filtration, and Backwash Disposal Alternatives

Four pre-treatment/filtration and three backwash disposal alternatives were considered for further evaluation, as described below. Based on the Indian River Filtration project evaluation by CH2M in 2012, cartridge or bag filtration was not considered for further evaluation due to the large footprint and lack of adequately sized ADEC approved equipment for the required flow. Seawater Desalinization was also discussed but not evaluated further because of the very high cost and complexity of treatment as well as the challenges of intake construction and brine disposal.

4.1 Dissolved Air Flotation (DAF) and Granular Media Filtration

DAF is a pre-filtration process that uses minute air bubbles to suspend low-density solids like algae, organic compounds, and some sediment to float the solids to the surface of the basin, and then skim the solids to a collection trough. These compounds are typically difficult to remove by conventional sedimentation processes because they settle very slowly, especially with colder water temperatures. Additionally, these compounds readily float out of high-quality water. DAF is an effective alternative to sedimentation or adsorptive clarification. With the use of flotation, smaller coagulant doses can be used to remove contaminants. Clarified water from the DAF process flows through a conventional multimedia filtration step to receive the filtration credits required for surface water treatment.

DAF is optimized when raw water average turbidities are between 0 and 10 NTU, with occasional spikes as high as 50 NTU, and TOC levels ranging up to 14 mg/L. Based on these requirements DAF would not be suitable for use at Indian River. The typical TOC values in Blue Lake and Sawmill Creek are low enough that the DAF process would likely provide more treatment than necessary, and based on conversation with DAF system manufacturers would be more expensive to construct and operate than some of the other options.

4.2 Granular Media Filtration

4.2.1 Process DescriptionA conventional granular media filtration facility would consist of a three-train package system. Each train would consist of pretreatment followed by filtration through a mixed media filter bed. Pre-treatment is dependent on water quality, raw water turbidity in excess of 75 NTU will require tube settlers followed by an up-flow adsorption clarifier. For raw water turbidity less than 75 NTU, just an up-flow adsorption clarifier is required prior to filtration. The system would be automated for coagulant dosing and control to respond to changing influent water quality. Appendix C includes additional details on the package granular media filtration options, and Photo 5 shows a schematic of an adsorption clarifier system. Several vendors supply this type of package equipment, which can provide competitive pricing during the equipment procurement phase of the project.

Filtered water would be pumped to an on-site tank to provide backwash supply and a buffer between the filter plant and the distribution system. Depending on the site of the plant, the tank could be sized

Photo 4 - DAF Package Plant


to provide CT, or just backwash supply. Figure 1 shows a conceptual plant layout and size for the three-train system.

Photo 5 - Adsorption Clarifier System

4.2.2 BackwashSolids are removed from the tube settlers using a gravity drain. This process is automated based on a timer. The up-flow clarifier process is periodically flushed with treated water to remove solids from the media. The granular media filter is also agitated with an air scour to remove solids during backwash. The waste streams would be discharged to the sanitary sewer or a secondary backwash recovery process to reduce loading the sewer system. For lower quality raw water that requires the tube settler, waste volumes are generally less than 5% of the total production (300,000 gallons/day at the full 6 MGD design capacity). For higher quality water with lower influent turbidity, waste volumes are around 3% of the total water production (150,000 gallons/day at the full 6 MGD design capacity). This assumes one backwash per day, which is the worst-case backwash requirement. Backwash handling is discussed in Section 4.4.

4.2.3 Startup, Shutdown, and Standby ConsiderationsWith an automated control system for coagulant dosing, the start-up time from standby of either pre-treatment system followed by filtration is fairly short. Upon startup, one full process tank volume should be filtered to waste to be sure the system is operating correctly and to flush any entrained solids from the storage period out of the system. After the operating period is complete, the system should be backwashed with chlorinated water and allowed to drain. No operator involvement is required to monitor the system when it is offline. There are not specific requirements for frequency of operation, but good practice would start the filtration system up a minimum of every 6 months to exercise all of the system components and maintain operator familiarity with the system.

4.2.4 Advantages/DisadvantagesAdvantages:

Relatively small footprint requirement.





Pre-treatment and granular media filtration is overall less complex than membrane filtration.

Disadvantages: Generally high quality water may be difficult to treat. With lower solids concentration in

the raw water, optimizing a solids removal process will likely be difficult.

Coagulant dosing is critical to successful filter operation. High quality source water may require higher coagulant doses.

Seasoned operator experience and judgment will be needed to optimize treatment process.

Additional water quality data from Sawmill Creek is needed to verify selection of the recommended pre-treatment process.

4.3 Membrane Filtration

4.3.1 Process DescriptionA package membrane filtration plant would be a direct filtration plant consisting of three membrane trains. The treatment equipment would include a pre-filter feed tank, coagulant injection, feed pumps to control flow through each membrane skid, self-cleaning screens to remove debris that could damage the membranes, membrane skids with racks, a filtered water tank, actuators, piping, and instrumentation, air compressors and blowers for backwash and membrane integrity testing, membrane cleaning chemical storage and feed systems, and backwash/chemical cleaning waste neutralization equipment. Photo 6 shows a typical membrane rack skid. Appendix C includes additional information on the membrane filtration equipment. Filtered water would be pumped from the individual filtrate tanks to the distribution system. Figure 1 shows a conceptual plant layout and size. Several vendors supply this type of package equipment, which can provide competitive pricing during the equipment procurement phase of the project.

4.3.2 Backwash The membranes would require three different types and intervals of cleaning. The membranes would be primarily cleaned with a reverse flow air/water backwash, which involves flowing treated water backwards through the membranes with air to remove particles on the outside of the membranes. This backwash would occur approximately every 20 minutes and last for about 2 minutes. Some solids and most organic materials are not removed through this process, so a more intensive cleaning

Photo 6 - Package Membrane System


process called Enhanced Flux Maintenance (EFM) using caustic soda and sodium hypochlorite would be performed approximately every 3 days. Lastly, a monthly intense chemical clean in place (CIP) using citric acid would be performed to remove organics and other membrane foulants not removed by normal backwash and EFM cycles. The regular backwash water could be discharged to the sanitary sewer. Alternately, the backwash could be settled with the decant water being recycled to the head of the filtration process with the solids being conveyed to the sewer or landfill depending on the solids percentage of the settled solids. The discharge from the chemical cleaning cycles would be neutralized using sodium bisulfite and be discharged to the sanitary sewer. Backwash handling is discussed in Section 4.4.

Typical membrane plant backwash quantities are approximately 10% of the process flow. For the full 6 MGD treatment capacity that CBS requires, this quantity can be up to 600,000 gallons/day.

4.3.3 Startup, Shutdown, and Standby ConsiderationsWith an automated control system for coagulant dosing, the start-up time from standby mode is approximately 4 hours. Upon startup, the system should operate in a filter-to-waste mode to flush any high chlorine residual water from the membranes. After the operating period is complete, the system should be backwashed (or a CIP performed, depending on the end of run transmembrane pressures) and dosed with chlorine to protect the membranes from biological growth. The chlorine residual should be monitored weekly, which can be done automatically or manually, and more chlorine added if the residual starts to drop. The membrane system should be operated at least every 6 months to exercise all of the system components and maintain operator familiarity with the system.


This technology is operationally familiar to operations staff from Blue Lake Dam project.

Requires a simple process to take filter plant online/offline.

Multiple trains allow for flexibility in operating loading rates, based on flow demands and water quality.

Chemical dosing is not critical to pathogen removal success because the membrane pore size excludes pathogens.

Automated system facilitates ease of intermittent operation.

Disadvantages: Large volume of backwash water must be managed.

Larger footprint than granular media option due to pre-engineered membrane solution. A custom engineered system could have a smaller footprint, but would have a higher cost due to engineering requirements by the equipment vendor.

More complex pumping systems will require more operator attention and involvement.

Higher chemical use than granular media options for EFM and CIP cleaning.

Less safe for operations staff due to chemical use for EFM and CIP cleaning.

More complex ancillary process for EFM and CIP waste neutralization prior to backwash


4.4 Backwash Disposal

Backwash volumes produced by the various filtration alternatives can be significant and there are many options for backwash disposal. The filtration system is planned for intermittent operation so complex backwash disposal options that provide a very high level of solids separation at a high cost or operational complexity were not considered. Space for this type of equipment could be reserved during design should the filtration facility be operated full time. Backwash disposal options would also be used to manage water produced during filter to waste cycles.

Backwash water is dependent on the raw water quality of the source. Typical backwash water quality is summarized in Table 6 - Typical Backwash Water Quality.

Table 6 - Typical Backwash Water Quality

Parameter Range

Total Suspended Solids (TSS) mg/L 100-1000

Biological Oxygen Demand (BOD) mg/L 2-10

Chemical Oxygen Demand (COD) mg/L 20-200

4.4.1 Disposal to Sanitary SewerDirect disposal to the sanitary sewer is the most simple disposal option. All backwash water and solids would be conveyed to the WWTP for treatment and disposal. Depending on the location of the facility, the capacity of the existing collection system may be inadequate for this option. Backwash flows are infrequent, but generally high in volume, so an equalization basin or tank would be provided to allow the flow to be pumped gradually into the sewer system. This would reduce the impact on the collection system and treatment plant.

The water quality of the backwash would impact the influent water to the WWTP. Any residual coagulant may increase solids removal in the clarifiers, which would increase the solids production by the WWTP. The BOD and TSS in the backwash water and the volume of the water would change the influent concentrations at the WWTP, which may impact the performance.

Advantages

Least complex disposal option.

Disadvantages

Would likely require very costly improvements to sanitary sewer collection system, depending on plant location.

May impact performance of the WWTP.

4.4.2 RecycleRather than sending backwash water directly to the sanitary sewer, the water could be settled in the equalization tank, which would be outfitted with a moveable floating decant arm, as shown in Photo 7. The decant water would be recycled to the start of the filtration facility. Recycle flows are typically limited to no more than 10% of the plant influent flow rate, and must be injected upstream of all treatment processes. The size of an equalization and decant tank would be based on the backwash volumes anticipated from the selected filtration process.


Solids from the bottom of the equalization tank would be pumped to the sanitary sewer or a secondary solids handling process. The amount of solids removed from the bottom of the clarifier will depend on the raw water quality. Like the full backwash flow, routing these solids to the WWTP may have an impact on the WWTP performance. In this case, it may increase the solids loading on the WWTP slightly.

Advantages

Reduces amount of backwash directed to the sanitary sewer.

Recycles water to the start of the WTP, reducing overall system waste.

Disadvantages

May impact performance of the WWTP.

4.4.3 Marine or Freshwater Outfall DischargeBackwash water, either with our without settling, could be disposed of in an existing storm drain system outfall. This discharge would require an APDES permit, governed by the ADEC general permit for Wastewater Discharges from Drinking Water Plants. The permit has effluent limits for chlorine, total dissolved solids, pH, aluminum, and arsenic. The effluent limits would require flow equalization and settling to remove solids prior to discharge. The permit would require monitoring of the regulated water quality parameters on a monthly basis and reporting of additional parameters semiannually.

Advantages

No or very low flow to the sanitary sewer, or impact to the WWTP.

Depending on permit requirements, may have no need for flow equalization.

Disadvantages

Requires APDES permit with reporting and monitoring requirements.

May be subject to changing discharge regulations over time.

Photo 7 - Equalization Basin With Floating Decant


5. Site and Source Alternatives

CBS has water rights in Blue Lake and Indian River for municipal use. There are two options for locations of a plant using Sawmill Creek as a water source: adjacent to the existing UV Facility, and at the old pulp mill filters. Development of new water sources was considered by CH2M in the 2018 Dedicated Water Line Report, and is not considered as part of this evaluation. Details of the water sources and potential WTP locations are summarized below.

5.1 Sawmill Creek – Adjacent to UV Facility

5.1.1 DescriptionThe UV Facility is located on Lot 18 in the Gary Paxton Industrial Park (GPIP) and has vacant lots on either side of it (Lot 17 and Lot 19) which could be used for the filtration facility. Sawmill Creek Road, an ADOT road runs along the north side of all three lots. The GPIP board has indicated that they would prefer that a filtration facility be located on Lot 19 because Lot 17 is more appealing for prospective developers. Both Lots 17 and 19 are currently owned by CBS and would need to be acquired by the water department prior to construction of a filtration facility.

Lot 17 is located to the east of the UV Facility. The site is bordered by Sawmill Creek Road to the north, and Sawmill Cove Industrial Park Road to the east. CBS’s raw water fire system main runs along the east side of the lot and a dysfunctional hydrant is located in the middle of the property, and would need to be abandoned along with the raw water line that bissects the property. There is also an abandoned utility pole on one side of the lot. The site is generally level, with good access for construction and operations, and straightforward connections to the existing utilities. Based on the geotechnical investigation performed prior to the UV Facility construction and preliminary geotechnical excavations, subsurface conditions are not complex for construction of a new facility. Photo 8 – Sawmill Creek Site - Lot 17 Adjacent to UV Facility shows the site. The site has adequate available electrical power supply for any of the pretreatment and filtration options considered. Figures 2 and 3 show the proposed plant location and size, intake and piping connections.

Photo 8 – Sawmill Creek Site - Lot 17 Adjacent to UV Facility


Lot 19 is located to the west of the UV Facility. The site is bordered by Sawmill Creek Road to the north and west, and the UV Facility to the east. There is an existing utility ROW to the south of the lot. The site is generally level though at an elevation several feet higher than the UV Facility with adequate access for construction and operations. A preliminary geotechnical investigation determined that large amounts of fill have been placed on top of old Pulp Mill structures and concrete foundations on the site, so a geotechnical investigation and significant excavation to make the site a similar elevation to the UV Facility site will be required to utilize the site. Photo 9 shows the site, Figures 2A and 3A show a potential site layout utilizing Lot 19. The site has adequate available electrical power supply for any of the pretreatment and filtration options considered.

Photo 9 - Sawmill Creek Site – Lot 19 Adjacent to UV FacilityOf the two lots adjacent to the UV facility, Lot 17 is the preferred location for a filtration facility. While it would be possible to locate the facility on Lot 19, several factors would drive up the construction cost and increase the complexity of operating the facility:

The existing fill and old tank foundations would need to be removed for site development.

The site would need to be excavated to a level similar to the UV Facility.

A retaining wall or other structure would be required to maintain the integrity of Sawmill Creek Road.

Connections to existing utilities (raw and treated water, potable water, sanitary sewer, power) would be more complex than Lot 17.

Access around a new facility on Lot 19 would be complicated, making regular operations more complex than necessary.

5.1.1.1 IntakeAn intake would need to be located in Sawmill Creek to pump water to the new filtration facility during penstock outages. During high turbidity events, water would be supplied from the existing penstock supply. The intake would consist of a wet well constructed in the river on the east bank, as close to the mouth as possible while avoiding any tidal water intrusion. The wet well would have a screen to prevent large debris and fish from entering the wet well. Submersible pumps would pump the water through a new pipeline, which would be routed along the base of the canyon walls paralleling the creek until the mouth of the canyon where it can be connected to the existing raw water piping. The new raw water line would be designed to be completely drained when not in use. A connection to the existing UV facility raw water line and treated water line


would be made to allow the plant to operate using the existing penstock water line during high turbidity events. It is assumed that adequate power is available at the pulp mill filters for the intake.

A geotechnical investigation evaluating the rock conditions of the Sawmill Creek canyon was completed in September 2018 by Shannon & Wilson. The report recommended placing the pipe at least 25 feet from the toe of canyon slopes to reduce potential for impact from rockfall. The report also recommended precast concrete block above-ground pipe supports with embedment. Buried installation is not practical due to groundwater and running ground conditions.

5.1.1.2 Pre-TreatmentThe available water quality data, which is currently very limited, from Sawmill Creek indicates that it is good with low turbidity, high UV254 transmissivity, and low organics and other contaminant concentrations. Additional data should be collected during storm events, fish valve releases, and dam spillover to confirm that this water quality will remain consistently high. Because the water flow in Sawmill Creek is substantially controlled by the CBS electrical department, the reach of the river is not subject to the same erosion and deposition events as Indian River.

Based on the good raw water quality, the overall pretreatment needs for Sawmill Creek are fairly low. For all of the alternatives, coagulant addition would be required to help remove the few organics that are present. Provisions are also included to mitigate the uncertainty of the raw water quality, during storm events or other assumed higher turbidity events, coagulation would be critical to help remove particles from the water. The coagulant will be injected as far upstream as practical with a rapid mixer to allow for the longest contact time with the water possible.

Up-flow Clarification & Granular Media Filtration - No tube settler pre-treatment would be required.

Membrane Filtration - Coagulant addition would enhance organics removal and improve long term membrane performance.

5.1.1.3 FiltrationAny of the filtration alternatives discussed in Section 4 would provide adequate treatment. The parcels adjacent to the UV Facility are small, so options with a smaller footprint would be favored at this site.

5.1.1.4 CTChlorine contact time (CT) would be accomplished by injecting chlorine at the UV Facility. This would require the installation of on-site hypochlorite generation equipment and the ancillary pumping equipment at the UV Facility, where space is already dedicated for this upgrade. The filtered water would flow through the UV Facility piping, chlorine would be injected, and the water would flow through the 30-inch transmission main to town, with CT reached along the pipeline before the first customer.

5.1.1.5 Backwash DisposalBackwash from any of the pre-treatment and filtration processes would be routed to an equalization basin and recycle system. Solids would be pumped to the sanitary sewer system. The entire GPIP is served by a lift station with a force main that pumps the sewage along Sawmill Creek Road through a series of lift stations to the WWTP for treatment. The lift stations along Sawmill


Creek Road are generally small, so recycling the backwash to reduce the volume or alternate backwash disposal is necessary.

The final option for backwash disposal would be to provide an ocean outfall via the existing GPIP storm drain system for either the settled solids if the backwash water is recycled or all of the backwash water if it is not.

5.1.1.6 Lot 17 Geotechnical EvaluationA geotechnical evaluation of Lot 17 was conducted in July 2018 that included subsurface drilling, sample collection, soil lithology, and observation of groundwater levels. The report indicated that the site is well suited to shallow foundations, with a potential of up to 1.0 inches of settlement. Construction recommendations include removal of all debris and deleterious material, with placement of 12-inches of fill to serve as subgrade for foundations.

5.1.2 Land RequirementsThe existing lot is bounded by roads with existing rights of way (ROW). The CBS ROW could be adjusted, if needed to accommodate the filtration plant footprint. The site would be combined with the UV Facility site, providing one access point and a continuous fence around both facilities.

5.1.3 Potential Construction ProblemsConstruction of an intake in Sawmill Creek will be challenging. In the area above the tidally influenced zone, the creek is in a narrow canyon with shallow bedrock. Construction of an intake wet well will require rock blasting in the canyon or construction of a fish-friendly dam. The routing of the raw water pipeline from the intake to the WTP may also require a significant amount of rock blasting. Rock blasting work in the Sawmill Creek canyon will require permitting and construction windows that minimize disturbances on the anadromous fishery in the creek.

The location adjacent to the UV Facility provides good construction access with minimal interruption to existing utility operations during the construction of the filtration facility and associated infrastructure.

5.1.4 Advantages/DisadvantagesAdvantages and disadvantages of utilizing Lot 17 are presented below

Advantages: High quality source water with adequate existing water rights.


Generally known and good geotechnical conditions for construction.

Available property with no need for demolition of existing infrastructure.

Disadvantages: Difficult to construct intake and pipeline to provide water during penstock outages.

Limited ability to handle large volumes of backwash water.


City and Borough of Sitka – Filtration Evaluation CRW Engineering Group, LLC Final Report ‐ UPDATE Page 23 April 2019

5.2 Sawmill Creek – At Pulp Mill Filters

5.2.1 Description

A pulp mill operated in Sawmill Cove for nearly 35 years. The mill was closed in the early 1990’s, with ownership of the mostly demolished infrastructure transferred to CBS in the late 1990’s. The pulp mill filter basins are located on the northeast side of Sawmill Cove above the BLWTP and hydropower facility, as shown in Photo 10. The filter basins are approximately 200 feet in length on each side, with some existing walls. This site is level, with bedrock and shallow gravel fill supporting the existing infrastructure. Figures 4 and 5 show the proposed plant location and size, intake and piping connections. The site has adequate available electrical power supply for any of the pretreatment and filtration options considered.

Review of the filter basin drawings indicate that the existing filter floors could be used as the building foundation. Depending on the final building design several modifications to the slab may be required including; a concrete pedestal on the existing slab, cutting the slab to provide larger footings, or rock anchors to mitigate overturning forces. The building should have a concrete curb with waterstop poured around the outside to prevent water from entering the building. During design, an evaluation of the existing pulp mill filter floors would be conducted to confirm the concrete strength and reinforcing locations. This evaluation would add approximately $25,000 to the design fee. If the evaluation determined that the existing foundation could not be used, the foundation would need to be demolished, and then an additional geotechnical investigation would need to be completed to determine the appropriate foundation design criteria for new construction. Demolition of the existing slab presents risks to the continued operation of NSRAA and fire suppression systems located on the east side of the filter bays. It was assumed that no significant structural issues would be encountered when estimating the cost of this option.

Additional challenges with utilizing the filter bay foundation include the flat floors. Extensive trenching would be required to install any below‐grade plumbing including floor drains and process piping.

Photo 10 ‐ Pulp Mill Filter Basins


5.2.1.1 IntakeAn intake would need to be located in Sawmill Creek to pump water to the new filtration facility during penstock outages. During high turbidity events, water would be supplied from the existing penstock supply. Photo 11 shows the potential intake location. The September 2018 geotechnical investigation of Sawmill Creek canyon detailed intake and routing options. The intake would consist of a wet-well constructed in the river on the east bank, near the waterfall that is formed from penstock and filter bay drainage. The wet-well would have a screen to prevent large debris and fish from entering the wet-well. Submersible pumps would pump the water through a new pipeline, which would be routed up the canyon wall to the west of the waterfall. Running the pipe up the rock wall will require tensioned rock anchors to hold the pipe to the rock wall as well as stabilize the rock face in the immediate area of the pipe alignment. The preliminary design of the rock anchors includes 1.5 to 3-inch threaded bars penetrating at least 30-feet into the rock face. Construction of the rock anchors is complex and fairly high risk.

A connection to the existing raw water line at the BLWTP would be made to allow the plant to operate using the existing penstock water line during high turbidity events. Power for the intake would come from the power supply for the new filter plant.

5.2.1.2 Pre-TreatmentThe pretreatment considerations for this option are the same as those for the site adjacent to the UV Facility and are discussed in Section 5.2.1.0.

5.2.1.3 FiltrationAny of the filtration alternatives discussed in Section 4 would provide adequate treatment. The site at the pulp mill is adequate for any of the filtration options.

5.2.1.4 CTChlorine contact time (CT) would be accomplished by injecting chlorine using the existing Blue Lake WTP gas chlorination system. Water would then flow through the 30-inch transmission main to town with CT reached along the pipeline before the first customer. When CBS is ready to replace the gas chlorination system, chlorine could be injected using an on-site hypochlorite generation system located at the UV Facility as described in the previous option.

5.2.1.5 Backwash DisposalBackwash from any of the pre-treatment and filtration processes would be routed to an equalization basin and recycled. Solids would be pumped to the sanitary sewer system, which would require the sanitary sewer line on the bridge crossing Sawmill Creek to be upsized. The entire GPIP is served by a lift station with a force main that pumps the sewage along Sawmill Creek Road through a series of lift stations to the WWTP for treatment. The lift stations along Sawmill

Photo 11 - Potential Intake Location in Sawmill Creek


Creek Road are generally small, so recycling the backwash to reduce the volume for disposal is required.

An alternate option for backwash disposal would be to provide an ocean outfall via the existing GPIP storm drain system for either settled solids if the backwash water is recycled or all of the backwash water if it is not. This would require construction of a new pipe connection to the existing GPIP storm drain system.

The existing utility bridge over Sawmill Creek is aged. CBS staff requested that if the bridge were utilized for this project, that a new bridge would be considered. An evaluation and recommendation for a new bridge was outside the scope of this review, but should be considered if this site is selected.

5.2.2 Land RequirementsThe existing facility has limited access and signage to keep out the general public. It is adequately sized to hold any of the filtration and pre-treatment options considered. Access would need to be maintained for the infrastructure that provides water to the hatchery as well as the existing bulk water delivery line. The filtration facility could be located to avoid any impacts to this existing infrastructure.

5.2.3 Potential Construction ProblemsConstruction of an intake in Sawmill Creek will be challenging. In the area above the tidally influenced zone, the creek is in a narrow canyon with shallow bedrock. Construction of an intake wet well will require rock blasting in the canyon or construction of a fish-friendly dam. The routing of the raw water pipeline from the intake to the WTP will also require a significant amount of rock blasting. Rock blasting work in the Sawmill Creek canyon will require permitting and construction windows that minimize disturbances on the anadromous fishery in the creek. The geotechnical report indicates that a contractor will need to be prepared for coarse gravel, shot rock, and bedrock, and that pneumatic hammers and drill and blast methods may be required in addition to conventional earthworking equipment.

Demolition of the existing pulp mill filter walls is anticipated to be straightforward using a concrete saw to only remove the desired portions of the wall. There is uncertainty and risk with any demolition work, which is higher with selective demolition that hopes to leave portions of an aged structure undisturbed.

The location at the pulp mill filters provides good construction access with minimal interruption to existing utility operations during the construction of the filtration facility and associated infrastructure.

5.2.4 Advantages/Disadvantages

Advantages: High quality source water with adequate existing water rights.

Level site with adequate space for facility.

Less complex intake pipe routing than the UV Facility location.

Good proximity to existing infrastructure (power, raw water, finished water).


Disadvantages: Some demolition of the existing pulp mill filters will be required for a reliable building

foundation.

Utilization of the existing filter base as the foundation will require a code waiver for minimum footing depths for frost protection.

The slab will act as a thermal bridge between the interior and exterior of the building, which may cause condensation problems and increase the heating cost for the building.

Need to provide sanitary sewer connection for backwash solids disposal, and limited ability to handle large volumes of backwash water due to wastewater collection system limitations along Sawmill Creek Road.

May need to provide new connection to GPIP stormwater system for backwash disposal.

Option does not provide a fully redundant source.

Difficult to construct and highly complex intake to supply water during penstock outages.

5.3 Indian River

5.3.1 DescriptionCBS’s existing Indian River infiltration gallery and pumping station property could be used for a filtration facility. The property is located at the end of Indian River Road and is located between a hiking trail and Indian River. The site currently has a perforated pipe intake and a gated culvert to move water from the river into an off-channel infiltration gallery. When in use, water was pumped from the infiltration gallery into the distribution system with chlorine addition. To use this facility for a permanent filtration system, the existing infrastructure would need to be demolished and a new intake and treatment plant constructed. Figures 6 and 7 show the proposed plant location and size, intake and piping connections. The site has adequate available electrical supply for any of the pretreatment and filtration options considered.

The existing municipal water right in Indian River is for 2.5 MGD. A larger water right would be required to provide a permanent filtration system. Additionally, Indian River was recently determined to be a “regulatory floodway” by FEMA. The regluatory floodway determination requires modeling of the river system for downstream impacts from any new construction.

The transmission main from the Indian River site enters the distribution system downstream of the CBS Corrosion Control Facility (CCF) where soda ash is injected for pH adjustment. For short term operations, the CCF can be taken offline.

5.3.1.1 IntakeA new perforated pipe intake would be set in Indian River below the river bottom. Setting the infiltration pipes deeper will allow the system to collect water even when streamflow is low. The pipes would need to be installed with large rocks placed to help keep alluvial material covering the pipes and protect them from large debris moving through the riverbed. The pipes would be

Photo 12 - Existing Perforated Pipe Intake


routed to a wet well constructed outside of the river channel, where pumps would be located to supply the filtration facility.

Depending on the final site layout and any influent head requirements for the treatment system, the raw water pumps from the temporary filtration project can be re-used, with additional pumps added to increase the flow from 4 MGD to 6 MGD.

5.3.1.2 Pre-TreatmentThe available water quality data and experience operating the temporary filtration plant during the Blue Lake Dam project show that the water quality at Indian River is highly variable. During good weather periods, the river has low turbidity, high UV254 transmissivity, and low organics levels. Storm events can increase turbidity to over 100 NTU in a matter of hours as well as increase organics levels, potentially leading to significant disinfection byproduct formation.

Based on this variability, pretreatment will be required prior to filtration for any options considered. For all of the alternatives coagulant addition would be required. The coagulant will be injected upstream of any flocculation and settling process with a rapid mixer to allow for the longest possible contact time with the water.

Up-flow Clarification & Granular Media Filtration – A tube-settler will be included in the treatment process to remove solids prior to clarification and filtration.

Membrane Filtration – Flocculation and settling is required upstream of the membrane process to remove solids prior to filtration. This would be done by construction of two concrete flocculation and settling basins that would be outfitted with parallel plate settlers to reduce the overall basin dimensions.

5.3.1.3 FiltrationOf the filtration alternatives discussed in Section 4, only the tube settler, up-flow clarification, granular media filtration option or membrane filtration with pretreatment would provide adequate treatment of Indian River water, due to the extremely variable nature of the water quality. The site is small and so smaller footprint options are preferred.

5.3.1.4 CTThere is inadequate time in the distribution system between the Indian River site and the first customer to achieve CT. A welded steel CT tank would be constructed to provide CT prior to pumping water into the distribution system. The CT tank would be baffled to achieve a minimum baffle factor of 0.5, which allows the tank volume to be 450,000 gallons (60 feet in diameter and 32 feet high).

After CT is achieved, the water will be pumped to the distribution system. The high service pumps from the temporary filtration project can be reused, with additional pumps added to increase the flow from 4 MGD to 6 MGD.

5.3.1.5 Backwash DisposalBackwash from any of the pre-treatment and filtration processes would be routed to the sanitary sewer system. This would require a main extension from the existing end of the system in Indian River Road. The lift stations between Indian River and the WWTP are better sized to accommodate the backwash flows from any of the pretreatment and filtration options than the Sawmill Creek alternatives.


5.3.2 Land RequirementsThe existing site is small, much of which is occupied by the infiltration gallery. To have adequate space for pretreatment and filtration, the infiltration gallery will need to be filled in to serve as the foundation for the new facility. Even with this additional space, the site is small, and access around the site may be difficult. CBS owns land on the far side of the existing hiking trail, so the site could be expanded with a trail re-route if needed.

5.3.3 Potential Construction ProblemsConstruction at the Indian River site would be fairly straightforward. Because the site is independent from the rest of the CBS infrastructure, no complicated tie in work would be required.


Fully redundant water source from Blue Lake and Sawmill Creek.

Simple intake design with less complex construction.

Sanitary sewer system better able to convey backwash water to WWTP.

Disadvantages: Inadequate existing water right, additional stream flow monitoring to facilitate an intake

that can capture the needed flow is necessary.

Significantly variable flow and riverbed complicates intake design and reliability challenging.

Water quality in the river is highly variable, requiring a larger and more complicated treatment plant to meet treatment requirements.

FEMA regulatory floodway designation would require extensive permitting work, which increases cost.

Location in distribution system requires a clearwell for chlorine contact time prior to distribution.


6. Selection of an Alternative

6.1 Cost Estimates

6.1.1 Capital CostsThe estimated capital costs for each alternative are presented in Table 7. To allow for comparison with the alternatives developed in the CH2M Dedicated Water Line report, the same allowances for construction contingency, design and permitting, construction management, and administration were included in the costs. Detailed cost estimates for each alternative are provided in Appendix D. Capital costs for the Pulp Mill filters were updated in April 2019 to reflect the results of the geotechnical investigation at the intake. No other costs were revised. Costs for the intake for Lot 17 will be updated as part of the intake concept design memorandum which is under development.

Table 7 – Capital Costs

Alternative Construction1 Design2 SDC2 Permitting2 Contingency3 Total ($M)

Up-flow Clarification &

Granular Media Filtration

$11,350,000 $1,420,000 $1,130,000 $100,000 $3,970,000 $18.0Sawmill Creek Lot

17Membrane Filtration $15,626,000 $1,420,000 $1,560,000 $100,000 $5,470,000 $24.2



$11,528,000 $1,440,000 $1,150,000 $100,000 $4,030,000 $18.3Sawmill Creek Lot

19Membrane Filtration $15,815,000 $1,440,000 $1,580,000 $100,000 $5,540,000 $24.5



$18,213,000 $2,280,000 $1,820,000 $100,000 $6,370,000 $28.8Sawmill Creek - At Pulp

Mill Filters Membrane

Filtration $23,790,000 $2,280,000 $2,380,000 $100,000 $8,330,000 $36.9

Flocculation, Settling, Up-flow

Clarification & Granular Media

Filtration

$14,247,000 $1,781,000 $1,420,000 $150,000 $4,990,000 $22.6

Indian River

Flocculation, Settling, and Membrane Filtration

$25,524,000 $2,137,200 $2,550,000 $150,000 $8,930,000 $39.3

1. The cost estimates are prepared based on preliminary information, and based on assumptions, vendor quotes, and preliminary estimates of quantities. The expected accuracy range for this type of estimate are -20% to -50% on the low end, and +30% to +100% on the high range side.

2. Estimates for design, engineering services during construction (SDC), and permitting are percentages of the construction value adjusted for project definition and complexity.

3. Contingency is set at 35% to match the CH2M Dedicated Water Line Report, and is the minimum recommended contingency for this project definition level.


6.1.2 O&M Costs The operation and maintenance costs for the intake and pumping systems for each alternative will be very similar. The different operation costs are dependent on the treatment technology selected rather than the location.

Table 8 – Daily O&M Costs

Treatment Technology

Up-flow Clarification & Granular Media Filtration Membrane Filtration

Chemicals1 $500/day $535/day

Power2 606 kWH/day 815 kWH/day

Startup/Shutdown Labor (hours) 9 6

Daily Operating Labor (hours) 5 5

Daily Operating Cost $900 $1,000

Startup/Shutdown Cost3 $2,000 $1,700

1. Assumes same coagulant dose for each water source. Indian River may have higher chemical use than Sawmill Creek due to lower quality raw water. Does not include chlorine cost, the dose is assumed to be the same for each.

2. Power consumption does not include raw water pumping, finished water pumping, or building use. Costs presented are for comparison of equipment provided for each technology.

3. Cost for one day of operation and one day of startup/shutdown.

Table 9 summarizes the annual O&M costs of a granular media filtration facility compared with the cost of operating the existing UV Facility. The operating costs for the filtration facility in this table assume 24 hour per day operation at an average annual flow of 3.0 MGD. The actual costs will vary based on flows, the final coagulation chemical selected, and the water quality which impacts the amount of chemical required. These costs should be reviewed and updated as the filtration facility design progresses.

Table 9 - Annual O&M Costs

6.2 Non-Monetary Evaluation

The relative advantages and disadvantages of the filtration alternatives and site and source alternatives are compared using a numerical scoring approach. The scoring process is summarized in selection matrices. The left column of the matrix contains important criteria that are considered for comparing the

Treatment System Annual Operating Cost

Existing UV Facility1 $275,000

Filtration Facility with Penstock Supply2 $531,000

Filtration Facility with Sawmill Creek Supply3 $600,000

1. Based on 2017 Actual Operating Expenditures for Water Treatment.2. Includes chemicals, power, labor, and finished water pumping.3. Includes raw water pumping, chemicals, power, labor, and finished water pumping.


alternatives. Each alternative was given a score (1 poor to 5 excellent) for each of the criterion. The scores for each alternative were summed to give a total score.

6.2.1 Location AlternativesTable 10 - Location Non-Monetary Scores summarizes the non-monetary evaluation of the location alternatives.

Table 10 - Location Non-Monetary Scores

Sawmill Creek - Adjacent to UV

Facility

Sawmill Creek - At Pulp Mill Filters Indian River

Weight Score Weighted Score Score Weighted

Score Score Weighted Score

Raw Water Quality 3 5 15 5 15 2 6Raw Water Availability (water rights) 4 5 20 5 20 2 8

Raw Water Availability (flow) 4 5 20 5 20 2 8

Intake Complexity 2 2 4 2 4 4 8Pre-Treatment Requirements 4 4 16 4 16 2 8

Ability to meet CT 2 5 10 5 10 2 4Backwash 2 3 6 2 4 4 8Construction Complexity 2 5 10 3 6 3 6

Total Score 101 95 56

6.2.2 Treatment Technology AlternativesTable 11 summarizes the non-monetary evaluation of the treatment technology alternatives.

Table 11 - Treatment Non-Monetary Scores

Upflow Clarification & Granular Media Filtration Membrane Filtration

Weight Score Weighted Score Score Weighted

ScoreOperational Complexity 4 4 16 3 12Treatment Performance 4 4 16 5 20Ease of Startup/Standby Transition 3 4 12 4 12Operations Need In Standby 1 4 4 3 3Amount of Backwash Production 3 5 15 3 9Reliability 4 4 16 5 20Safety 3 5 15 4 12

Total Score 94 88


7. Conclusion and Recommendations

7.1 Conclusion

Based on the evaluation of capital and operating costs and non-monetary factors, an intermittent filtration plant treating Sawmill Creek water and located on Lot 17 adjacent to the existing Ultraviolet (UV) Facility is the recommended alternative. The primary advantages of this option are lower capital and operational treatment costs due to higher quality source water that allows for more affordable treatment options.

The advantages and disadvantages of the recommended alternative are summarized below, and have been updated in April 2019 based on the work completed since this report was published in April 2018.

Advantages: Generally high quality source water with adequate existing water rights. The good water quality has

been confirmed through extensive water quality testing throughout 2018.


Generally known and good geotechnical conditions for construction, which was confirmed with the Lot 17 geotechnical evaluation in 2018.

Available property with no need for demolition of existing infrastructure, and associated risk with selective demolition.

Relatively small footprint requirements.




Disadvantages: Difficult to construct intake and pipeline for conveying water during penstock outages.

Limited ability to treat and dispose of large backwash water volumes, which may be mitigated with backwash recycling or ocean discharge.


Coagulant dosing will be critical to successful filter operation. High quality source water may require higher coagulant doses.

Seasoned operator experience and judgment will be needed to optimize treatment process. Vendor or engineering support during the first few operational periods would help provide operator training.

Additional water quality data from Sawmill Creek is needed to verify selection of the recommended pre-treatment process. Sampling was conducted throughout 2018, and benchtop testing of treatment chemicals is underway in spring 2019.


7.2 Recommendations

The intake construction in Sawmill Creek has the most uncertainty of the various components of the project. To help alleviate some of this uncertainty, survey and geotechnical work should be completed as soon as practical. To move forward with the selected alternative, the following activities should be pursued.

Continue collection of water quality data, especially during high flow and poor water quality conditions to help identify the worst case water that will need to be treated.

o Started in 2018, continuing into 2019.

Work with ADEC to determine sampling required to establish a new source.

o Sampling is underway.

Perform a geotechnical investigation that includes drilling rock cores to locate the intake. This work will allow for early site development and preliminary permitting activities, as well as facilitate the design of the intake and filtration building foundation.

o Geotechnical evaluations were completed in the second half of 2018.

Perform a detailed survey of the intake location and site.

Evaluate construction strategies to quickly and cost-effectively complete the project.

Once the equipment supplier is selected, move forward with design, permitting, and construction.

If the selected alternative requires a crossing of Sawmill Creek on the existing utility bridge, an evaluation of options to replace or augment the bridge should be performed.

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Appendix A

Water Quality Data

City and Borough of Sitka ‐ Temporary Filtration Design

Sawmill Creek ‐ Daily Samples

Average 0.62 94.55 11.45 7.03

Min 0.44 92.80 9.20 6.70

Max 0.98 95.80 12.90 7.23

Date Turbidity (NTU) Notes UV254 ALK PH

1/9/2018 0.44 light snow

1/10/2018 0.47 O/C 1" snow on ground

1/11/2018 0.46 clear, 1" snow on ground

1/12/2018 0.48 P/C, light snow on ground.

1/15/2018 0.48 P/C , very warm, (60's), snow gone.

1/16/2018 0.59 O/C Intermittent Showers

1/17/2018 0.50 O/C 94.9

1/18/2018 0.48 C

1/19/2018 0.50 C 95.1 12.4 7.00

1/22/2018 0.52 snow, 2" on ground

1/23/2018 0.52 snow, 2" on ground

1/24/2018 0.46 snow, 2" on ground

1/25/2018 0.55 O/C 6.7

1/29/2018 0.51 C

1/30/2018 0.47 C

1/31/2018 0.48 C

2/1/2018 0.68 O/C

2/2/2018 0.64 O/C 12.4

2/5/2018 0.54 C

2/6/2018 0.55 Light Snow

2/7/2018 0.48 C

2/8/2018 0.46 C

2/9/2018 0.52 C

2/12/2018 0.80 Rain 95.5 11.5 6.85

2/13/2018 0.72 snow

2/14/2018 0.58 snow

2/15/2018 0.56 Snow

2/16/2018 0.66

2/20/2018 0.84 C 95.3 10.1 7.23

2/21/2018 0.79 O/C

2/22/2018 0.57 O/C

2/23/2018 0.59 rain

2/26/2018 0.76 snowy rain 95.2 10.8 7.04

2/27/2018 0.69 snow

2/28/2018 0.62 snow

3/1/2018 0.98 clear

3/5/2018 0.68 clear

3/6/2018 0.77 overcast 95.8 9.2 6.97

3/7/2018 0.66 overcast

3/8/2018 0.66 overcast

3/9/2018 0.65 light rain

3/12/2018 0.56 light rain 92.8 11.4 7.04

3/13/2018 0.53 light rain

3/14/2018 0.67 clear

3/15/2018 0.61 clear

3/16/2018 0.55 clear

3/19/2018 0.72 light rain 93.5 11.5 7.21

3/20/2018 0.81 light rain

3/21/2018 0.72 clear

3/22/2018 0.63 overcast

3/23/2018 overcast

3/26/2018 0.79 overcast 93.8 12.9 7.09

3/27/2018 0.88 rain

3/28/2018 0.88 clear

3/29/2018 0.62 clear

3/30/2018 0.68 clear

4/2/2018 0.51 clear 93.6 12.3 7.18

4/3/2018 0.68


Sawmill Creek Water Quality Results

Analyte 1/29/2018 2/26/2018 3/19/2018

Aluminum (ug/L) ND 64.9 ND

Iron Total (ug/L) 32.9 159 ND

Iron Dissolved (ug/L) ND 48.3 ND

Manganese (ug/L) 6.3 11.1 5.6

Organic Carbon, Total (mg/L) 0.732 0.887 1.1

Hardness, Total (mg/L as CaCO3) 8 16 11

Alkalinity, Total (mg/L as CaCO3) ND ND 13

Conductivity (umhos/cm) 35.6 37.2 34

Total Dissolved Solids (mg/L) 41 68 ND

Total Suspended Solids (mg/L) 0.8 3 ND

Silt Density Index (%/min) 6.62 7.29 6.74

Potassium (mg/L) ND

Sodium (mg/L) 1.4

Sulfur (mg/L) 0.6

Barium (mg/L) 0.0093

Magnesiium (mg/L) ND

Strontium (mg/L) 0.0089

Chloride (mg/L) 2.1

Nitrate as N (mg/L) 0.44

Fluoride ND

Sulfate (mg/L0 2.2

Ammonia (mg/L) 0.14

Silica, molybdate‐reactive (mg/L) 1.8

orto‐Phopshpate (mg/L) ND

Organic Carbon, Dissolved (mg/L) 1.6

Color, True ND

J ‐ estimated value below reporting limit


Indian River ‐ Daily Samples

Collected daily from the run of the river upstream from the infiltration pond inlet

Average 1.35

Min 0.25

Max 12.80

Date Turbidity (NTU) Date Turbidity (NTU)

7/1/2013 1.78 9/12/2013 1.62

7/2/2013 0.33 9/13/2013 1.52

7/3/2013 0.52 9/16/2013 0.68

7/5/2013 0.32 9/17/2013 0.88

7/8/2013 0.86 9/18/2013 1.21

7/9/2013 0.86 9/19/2013 1.32

7/10/2013 0.75 9/20/2013 2.28

7/11/2013 0.60 9/23/2013 0.74

7/12/2013 0.51 9/24/2013 0.78

7/15/2013 0.48 9/25/2013 0.72

7/16/2013 0.40 9/26/2013 0.88

7/17/2013 0.37 9/27/2013 1.05

7/18/2013 0.25 9/30/2013 1.25

7/19/2013 0.33 10/1/2013 0.71

7/22/2013 0.28 10/2/2013 0.57

7/23/2013 0.35 10/3/2013 0.58

7/24/2013 0.98 10/4/2013 0.67

7/25/2013 1.58 10/7/2013 0.64

7/26/2013 0.34 10/8/2013 0.40

7/29/2013 0.72 10/9/2013 1.12

7/30/2013 0.52 10/10/2013 11.10

7/31/2013 0.45 10/11/2013 8.55

8/1/2013 0.47 10/14/2013 6.26

8/2/2013 0.51 10/15/2013 2.12

8/5/2013 0.80 10/16/2013 1.14

8/6/2013 0.55 10/17/2013 1.02

8/7/2013 0.60 10/20/2013 12.80

8/8/2013 0.57 10/21/2013 1.37

8/9/2013 0.66 10/22/2013 1.11

8/12/2013 0.77 10/23/2013 0.84

8/13/2013 0.92 10/24/2013 0.86

8/14/2013 1.04 10/25/2013 0.80

8/15/2013 1.10 10/28/2013 0.42

8/16/2013 1.18 10/29/2013 0.41

8/19/2013 1.45 10/30/2013 0.64

8/20/2013 1.57 10/31/2013 1.12

8/21/2013 1.58 11/1/2013 0.88

8/22/2013 1.60 11/4/2013 0.33

8/23/2013 1.74 11/7/2013 0.40

8/26/2013 1.74 11/8/2013 0.44

8/27/2013 1.28 11/12/2013 0.34

8/28/2013 1.72 11/13/2013 0.38

8/29/2013 2.13 11/15/2013 2.05

8/30/2013 1.88 11/19/2013 0.53

9/3/2013 1.92 11/22/2013 0.61

9/4/2013 2.02 11/25/2013 0.83

9/5/2013 2.55 11/26/2013 2.04

9/9/2013 1.88 11/27/2013 2.08

9/10/2013 1.68 11/29/2013 2.46

9/11/2013 1.72 12/2/2013 0.42


Indian River ‐ Weekly Samples

Collected daily from the run of the river upstream from the infiltration pond inlet

min ‐0.28 ‐6.7 9.8 0.031

max 12.8 7.5 20.4 0.26

average 1.57625 7.1 15.76956522 0.078681818

Date

Turbidity

(NTU) pH

Total Alkalinity

(mg/L as CaCO3) UV 254 (cm‐1) Notes

7/2/2013 0.33 7.3 13.3 0.097 River was high from rainfall 0.35

7/8/2013 0.86 6.7 10.2 0.260 River was high from rainfall 0.60

7/15/2013 0.48 7.5 17.7 0.037 River was low

7/22/2013 0.28 6.8 16.5 0.032 River was low

7/29/2013 0.71 6.8 16.0 0.033 River was low

8/5/2013 0.80 6.8 16.2 0.051 River was low Rainfall/Fish in Creek

8/12/2013 0.77 6.8 18.2 0.033 River was low/Fish in Creek





9/16/2013 0.68 7.1 20.4 0.033 River was low/Fish in Creek No Rain

9/23/2013 0.74 7.2 15.9 0.126 Lots of Rain over Weekend




10/20/2013 12.8 7.3 none none River was high, 1.6 inches of rain


10/28/2013 0.42 7.3 11.3 0.06 River is low and Clear




11/25/2013 0.83 7.3 13.8 River is low and Clear



Indian River ‐ Weekly Samples

Collected from the run of the river, upstream of the gate that allows water into the pond

7/30/2013 8/29/2013 10/1/2013 10/9/2013 10/29/2013 12/3/2013

Run of River Run of River Run of River Run of River min average max

Alkalinity, Carbonate (mg/L as CaCO3) ND ND ND 0.00 #DIV/0! 0.00

Alkalinity, Bicarbonate (mg/L as CaCO3) 15.1 14.8 14.8 14.80 14.90 15.10

Alkalinity, Total (mg/L as CaCO3) 20.4 22.8 17.6 15.1 14.8 14.8 14.80 17.58 22.80

Aluminum, Total (mg/L) 0.0157 0.0746 0.0213 0.539 0.0504 0.0882 0.02 0.13 0.54

Ammonia‐N (mg/L) 1.09 1.09 1.09 1.09

Barium (mg/L) 0.00476 0.00 0.00 0.00

Carbon Dioxide (ug/L) 7410 7410.00 7410.00 7410.00

Chloride (mg/L) 2.92 2.92 2.92 2.92

Chlorine, Total (mg/L) 0.01 0.01 0.01 0.01

Color, Apparent (CU) 6 6.00 6.00 6.00

Color, True (CU) 6 6.00 6.00 6.00

Conductivity (umhos/cm) 52.6 71.5 54.8 50.1 45 51.1 45.00 54.18 71.50

Copper (mg/L) 0.00236 0.00 0.00 0.00

Fluoride (mg/L) 0.01 0.01 0.01 0.01

Hardness, Calcium (mg/L) 15.2 16.8 13.7 15.4 13.70 15.28 16.80

Hardness, Total (mg/L as CaCO3) 17.7 23.4 19.4 17.8 16 18.3 16.00 18.77 23.40

Iron, Dissolved (mg/L) 0.029 0.0238 0.157 0.072 0.0494 0.02 0.07 0.16

Iron, Total (mg/L) 0.06 0.28 0.0413 0.115 0.163 0.04 0.13 0.28

Magnesium (mg/L) 0.831 0.83 0.83 0.83

Manganese, Total (mg/L) 0.00188 0.0111 0.00316 0.0522 0.00495 0.00884 0.00 0.01 0.05

Nitrate‐N (mg/L) 1.2 1.20 1.20 1.20

Organic Carbon, Dissolved (mg/L) 1.04 1.04 1.04 1.04

Organic Carbon, Total (mg/L) 0.77 1.5 1.64 6.2 2.49 0.81 0.77 2.24 6.20

pH 7.12 7.29 7.24 6.8 7.15 7.25 6.80 7.14 7.29

Phosphate, Ortho as P (mg/L) 0.18 0.18 0.18 0.18

Phosphate, Total as P (mg/L) 0.26 0.26 0.26 0.26

Potassium (mg/L) 0.809 0.81 0.81 0.81

Silica, Colloidal (mg/L) 3.89 4.45 4.09 2.82 3.77 4.21 2.82 3.87 4.45

Silica, Reactive (mg/L) 4.3 4.30 4.30 4.30

Silt Density Index (%/min) 16 73 16.00 44.50 73.00

Sodium (mg/L) 2.57 2.57 2.57 2.57

Strontium (mg/L) 0.0248 0.02 0.02 0.02

Sulfate (mg/L) 2.99 2.99 2.99 2.99

Sulfur (mg/L) 1.21 1.21 1.21 1.21

Total Dissolved Solids (mg/L) 58 48 55 64 62 23 23.00 51.67 64.00

Total Suspended Solids (mg/L) ND 5.2 ND ND ND 5.20 5.20 5.20

Turbidity (NTU) 0.2 1.8 0.7 2.1 0.9 0.20 1.14 2.10

UV 254 (cm‐1) 0.027 0.035 0.4 0.1 0.044 0.03 0.12 0.40

Notes

Appendix B

Correspondenceand Trip Report

Phone Call

Anchorage Office: 3940 Arctic Blvd. Suite 300, Anchorage, AK 99503 | (907) 562-3252 fax (907) 561-2273Palmer Office: 808 S. Bailey St. Suite 104, Palmer, AK 99645 | (907) 707-1352 www.crweng.com

Date: 2/2/2018 1:30 PM - 1:45 PMInvitees: Rebecca Venot, Christi Meyn, Scott ForgueAttendees: Rebecca Venot (CRW Engineering Group LLC), Christi Meyn (CRW Engineering Group,

LLC), Scott Forgue (State of Alaska, Dept. of Environmental Conservation)Reporter: Rebecca Venot – CRW Engineering Group, LLCLocation: Call to Scott ForgueProject: CBS Filtration EvaluationSubject: Filtration Alternative Regulation DiscussionComments:

Rebecca and Christi called Scott Forgue to discuss the regulatory requirements of filtration in Sitka. We outlined that we are evaluating filtration alternatives for use by Sitka during times the existing supply is not useable for either:1. Hydropower facility pentstock use2. Water quality in Blue Lake that does not meet the filtration avoidance requirements. Indian RiverWe noted that Sitka does not currently have adequate water rights for normal situations, and would need to pursue additional water right. We explained that a permanent facility at Indian River would include:

Intake improvements

Pretreatment (coagulation/settling) for organics and turbidity removal

Filtration

Chlorine Injection

CT Tank

Scott said he was glad that we were considering a more permanent installation that would include better pretreatment and CT than the temporary project in 2014. The facility would require 3 log giardia, 3 log cryptosporidium, 4 log virus treatment unless Sitka wants to sample for a bin determination for crypto. Sawmill Creek

We explained that a secondary intake would be provided downstream of the dam with a full filtration facility.

Scott asked how we would work that into the existing infrastructure and piping schematic, and we noted that this is a big part of our project.

The filtration plant would require the same level of treatment as Indian River.

Blue Lake Filtration Avoidance Waiver

Scott said that the filtration avoidance waiver at Blue Lake would not be impacted by a secondary intake at Sawmill Creek. Utilizing different intakes with different treatment regimes is acceptable. There is nothing Scott is aware of in the state or

CBS Filtration Evaluation

2 of 2

federal regulations that would indicate a requirement to filter all of the time once filtration is started.

Scott also mentioned that Shilo had recently asked about declaring an intake at Sawmill Creek a filtration avoidance source. Scott provided her the sampling and source protection requirements, and admitted that it seemed doubtful that the source protection could be adequately met, and the water quality is likely not in compliance with the filtration avoidance requirements.

Cc: Shilo Williams (City and Borough of Sitka)

Site Visit


Date: 2/21/2018 9:15 AM - 6:15 PMInvitees: Rebecca Venot, Christi Meyn, Shilo Williams, Joe SwainAttendees: Rebecca Venot (CRW Engineering Group LLC), Christi Meyn (CRW Engineering Group,

LLC), Shilo Williams (City and Borough of Sitka), Joe Swain (City and Borough of Sitka)Reporter: Rebecca Venot – CRW Engineering Group, LLCLocation: SitkaProject: CBS Filtration EvaluationSubject: Filtration Evaluation Site VisitComments:

Tuesday February 20Christi and Rebecca departed Anchorage at 9:45 pm, arriving in Sitka just after midnight and proceeded directly to the hotel. Wednesday February 21We met with Shilo and Joe at Shilo's office to go over the filtration packages and overall project details.

Membrane filtration - Pall

o Could use 3 trains for 6 MGD at Indian River with flocculation/settling pre-treatment.

o Depending on the water quality at Sawmill Creek may be able to do direct filtration without a flocculation/settling process

o Good discussion with Pall on intermittent operation

chlorine used to control growth in the membranes

Weekly chlorine check, with additional added if needed is typically all that's required for standby

Generally 1 day or less to prep system for operation.

Membrane filtration - H2O Innovation

o No response to request for additional information and increased flows yet.

Flocculation/Settling - MRI

o Basins with plate settlers for flocculation/settling

o Either 2 3MGD trains or 3 2 MGD trains, built as concrete basins.

o Either option is a similar size.

Granular media filtration - WesTech

o Package 3 train system with flocculation, settling, and filtration.

o Fairly small footprint

o Operational concerns with intermittent operation - CRW needs to follow up with WesTech for a discussion on this topic.

Backwash


2 of 4

o Can consider a basic recycle system, but due to intermittent nature, focus more on sending the backwash water directly to the sanitary sewer.

o Need to consider sizing of wastewater system between filter plant and WWTP, as well as impacts on WWTP operation

o Additional backwash flow will not be a concern for WWTP capacity as WWTP reaches approximately half of capacity during storm events in peak season.

o Need to look into existing EPA discharge permit and if the addition of backwash will exceed flow limitations or other requirements

o Provide space for potential future backwash handling on site if filtration use becomes a longer-term solution.

Limited alternative to filtration

o Could be useful, safe drinking water act allows each state to develop their own additional requirements.

o Typically includes at least 1 log extra microbial inactivation requirement.

o Washington state is the only state that has their own regulations in place

o Will call Scott Forgue to discuss in detail

Shilo provided an update on her desalinization research

o Currently has a quote for $10M for the desal equipment only, that does not include intake, pre-treatment, pumping, outfall for brine, building, or any other system components.

The team then visited the Indian River site. Intake

Current water right is for only 2.5 MGD. Temporary project had a temporary water right for larger withdraw.

River level currently so low that the intake configuration to provide water is uncertain.

USGS stream gage for 2/21 indicated the flow was approximately 4,400 gpm (approx 6.2 MGD), so enough water may be available in the creek.

The intake dam area had big logs that had not been there on previous visits

Best option is likely an infiltration gallery, similar to the existing piping, but located deeper in the riverbed to allow the riverbed to shift and change above the piping, plumbed to a wet-well where pumps could be located.

Smaller slots on the screens than the current configuration would reduce the gravel build-up in the piping.

Site Layout With pre-treatment, need nearly all of the available space- would need to fill in the

existing infiltration pond or utilize it as excavated subgrade for pre-treatment.

Clearwell about 600,000 gallons needed to achieve CT for the first customers.


3 of 4

Finished water pumping required, could re-use pumps from temporary project.

CBS owns the property on the other side of the hiking trail, but would need significant development and re-routing of the trail.

After lunch, we went to the UV facilitySite Layout

Property adjacent to UV facility is potentially available, lot lines can be adjusted.

Site has a raw water line for fire suppression and a hydrant that would need to be relocated.

In general tie-in to main similar to the way the UV facility ties into the existing mains, no need to connect filter plant to UV plant directly

Property across the street from the UV facility is considered high value by the industrial park, and would be challenging to secure.

We then visited the pulp mill filtersSite Layout

Adequate space, level, already owned by the city

Some existing infrastructure in southwest corner (bulk water and hatchery supply lines)

Would require significant demolition

We visited the Thompson Harbor wastewater lift station and then wrapped up the day. Thursday February 22We toured the wastewater treatment plant as part of the WWTP building envelope/HVAC assessment. We hiked up the canyon at Sawmill Creek to evaluate intake options.

CBS controls the flow in SMC, so the river is much less dynamic than Indian River (dam blocks most flood events and sediment transport)

The creek is subject to saltwater intrusion at the mouth and at least up to the tailrace of the hydropower facility, so a water system intake would need to be upstream of any tidal influence. The extent of tidal influence needs to be determined.

Electric department provides a minimum of 50 cfs (22,400 gpm) in the stream at all times, additional releases for water supply are not a problem.

Likely intake construction would be similar to the dam's backup hatchery supply pumps - a concrete structure with screen, and vertical turbine pumps.

We visited the hydropower facility tailrace to look at the hatchery pumps

Tailrace is subject to saltwater intrusion, so this location wouldn't work for water supply pumps


4 of 4

Design is simple, using vertical turbine pumps

Could get drawings from electric utility if needed.

We visited the Blue Lake WTP to discuss connection points to the existing system

If a filter plant was located at the pulp mill filters, could connect to the penstock and existing water system at the Blue Lake WTP, utilizing existing chlorination equipment.

Pipe may need to be above ground with provisions for draining when not in use due to rock excavation required to get up above the penstock.

We debriefed at Shilo's office and Christi returned to Anchorage on the evening flight. Rebecca remained in Sitka for the WWTP HVAC/building envelope project on 2/23, and departed that evening.

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Phone Call


Date: 4/6/2018 9:40 AM - 9:55 AMInvitees: Rebecca VenotAttendees:Reporter: Rebecca Venot – CRW Engineering Group, LLCLocation: Phone Call to Scott ForgueProject: CBS Filtration EvaluationSubject: Turbidity Events & Secondary SourceComments:

Rebecca called Scot to discuss details of managing water sources if filtration is installed. If filtration is installed on Sawmill Creek, Sitka will develop SMC as a secondary source to use during penstock outages or other problems.

Current alternatives analysis shows use of the penstock to supply water to the filter plant if the penstock is in service and there is a high turbidity event.

We are concerned that this would impact the filtration avoidance waiver on Blue Lake, and that we should remove this connection from the study, and plan to only rely on SMC during high turbidity events.

Scott replied that it shouldn't impact filtration avoidance if water from the penstock is filtered during high turbidity events.

CFR indicates that filtration is required when the source can't meet filtration avoidance requirements, but the CFR is silent on the exact nature of how this is implemented.

Scott cited

o Juneau's ability to shut down filtration avoidance and use wells during the time they were maintaining filtration avoidance (have since installed filtration.

o Cordova has several sources that it utilizes based on water quality.

Our proposed method is a different way of solving the same problem.

Cc: Shilo Williams (City and Borough of Sitka)

Appendix C

Vendor Data

16133 W. 45th Dr. Golden, Colorado 80403

Tel (303) 279-8373 Fax (303) 279-8429

1

BUDGET PROPOSAL

FOR

FLOCCULATION / SEDIMENTATION SYSTEM

The following is a proposal for the above referenced project. It includes two (2) complete

flocculation/sedimentation systems, with each train designed at 3 MGD, as described below.

Flocculation:

A 3-stage Horizontal Paddle-wheel flocculation system will be provided based on the following design parameters:

Design flow per train: 3 MGD (2,083 gpm) Detention time at design flow: 45 minutes

No. of stages per train: 3 Basin dimension (L,W,D): 35 ft x 25 ft x 15 ft (SWD)

Dimension of each stage (L,W,D): 11 ft x 25 ft x 15 ft (SWD)

Design G-value 1st Stage (Horsepower): 60 Gsec-1 (2 HP) Design G-value 2nd Stage (Horsepower): 45 Gsec-1 (1 HP)

Design G-value 3rd Stage (Horsepower): 30 Gsec-1 (0.5 HP) Each flocculator system shall consist of:

1. Drive motor

2. Gear reduction gear box 3. VFD drive 4. Plastic/Stainless steel drive chain

5. Plastic/Stainless steel chain sprockets 6. Stainless steel shafts

7. UHMW-PE Split shaft bearings 8. Mixing paddles 9. All necessary brackets and fasteners including anchor bolts

Drive motor:

DATE: February 8, 2018

PROJECT: Sitka, AK REPRESENTATIVE: Chris Hanson

PHONE: 303-279-8373


Tel (303) 279-8373 Fax (303) 279-8429

2

The drive motor will be a 230/460 3 phase, totally enclosed, fan cooled, inverter duty rated, and premium efficiency. The horsepower will be determined based on the load requirements, the

velocity gradient values, drive efficiencies and a predetermined safety factor.

Gear reducer:

The gear reduction is selected based on the required ratio to achieve the desired tip speed and

horsepower for the process. All gear reduction units are to be Eurodrive with a AGMA II service factor and are provided with severe duty features and wash down ability.

Variable frequency drive:

An Allen-Bradley VFD will provide variable speeds to optimize the flocculation process. The VFD will be connected to the SCADA via Ethernet or hard wire for monitoring and operating

functions. A torque monitor will protect the drive unit in case of a stall.

Chain and sprockets:

Chain and sprocket - The chain and sprocket transfers the power from the VFD to the drive shaft

which is located underwater. The sprockets are T-304 stainless steel body and nylon teeth with T-304 stainless steel hardware. The chain is plastic or stainless steel dependent upon load.

Drive shaft:

The stainless steel shaft is sized based on process loads and horsepower. The shaft, hubs, turned down bearing sections are all T-304 stainless steel.

Drive shaft bearing:

The drive shaft bearings are located underwater. The bearings are UHMW-PE split-type and do not require grease. The bearings will be mounted on adjustable 304 S.S. bases to insure proper alignment.

Mixing paddles:

All paddles are made of 22 gauge 304 stainless steel. Each paddle will be 2” x 6”. The size and number paddles will be based on the desired velocity gradient.

Plate Settlers: An inclined plate settler system will be provided based on the following design parameters:

Design flow per train: 3 MGD (2,083 gpm)

Plate loading rate: 0.25 gpm/ft2


Tel (303) 279-8373 Fax (303) 279-8429

3

Plate area efficiency factor: 90% Basin dimension (L,W,D): 40 ft x 25 ft x 15 ft (SWD)

Dimensions of plate settler system (L,W,D): 24 ft x 24 ft x 9.4 ft Plate settlers per cartridge: 95

Plate cartridges per basin: 4 (4 rows x 1 cartridges) Effluent trough size: 12” x 12” (Inner) & 8” x 10” (Outer)

Head loss through system: 0.83 ft (estimated)

The inclined plate settler systems shall comprise the following elements:

1. Plate settlers w/ patented flow control deck 2. Effluent troughs w/ adjustable weirs

3. Support beams 4. Inlet Diffusers

5. All necessary brackets and fasteners including anchor bolts All components are of T-304 stainless steel, unless otherwise specified.

Plate settlers:

The plate will be manufactured of 24 gauge minimum thickness. The plates will be shipped in packs which will allow installation with a crane. The plates will be inclined at an angle of 55°

from the horizontal. The effluent flow at the top of the plate will be removed by the patented flow control deck. The flow will be removed across the full width of the plate in at least four (4)

points to insure even distribution across the full width of the plate. Effluent Troughs:

The effluent troughs will be located beside the plate rows and not over the plate rows to insure

complete visibility of the plate settlers. The effluent troughs will be fastened to the supporting frames no less than every 24 inches to insure stability. The effluent troughs will be equipped with adjustable weirs to insure even flow distribution between the plates.

Support Beams:

The support beams shall be sized accordingly to support the plate packs within the specified deflection.

Inlet Diffusers:

The inlet diffusers mount over the inlet ports to reduce incoming velocities. The diffusers are sized to reduce the incoming flow velocity by a factor of 4. The diffusers are manufactured from

304 stainless steel and mount with wedge anchors, which are included.


Tel (303) 279-8373 Fax (303) 279-8429

4

Sludge Collection:

A sludge collection system will be provided based on the following design parameters:

The sludge collector systems shall comprise the following elements:

1. Header Assembly

2. Sludge Exit Pipe 3. Drive Unit 4. Control System

All equipment is to be 304 stainless steel.

Header Assembly:

Each Hoseless Cable-VacTM will have a header assembly designed to remove the settled solids from the basin floor via tangential feed orifices. The header assembly will be guided by the basin

walls without the need of a rail. The Header Assembly consists of four 3” Dia. Suction header pipes and a 6” Dia. Collection Chamber. The solids are removed through orifices in the header pipes and travels into the collection chamber. The flow then enters the sludge exit pipe and exits

the basin. The header assembly and orifices within will be sized by the manufacture according to the hydraulic requirements. The suction headers are equipped with Scraper Blades assure

complete removal of solids at the ends of the basin. Sludge Exit Pipe:

The 4” Dia. Sludge Exit Pipe extends from one end of the basin to the midpoint of the basin. The

main body of the header assembly telescopes over the sludge pipe as it travels down the basin. The sludge exit pipe will terminate at the desired end of the basin, with a 4” Pipe Flange. The customer will need to provide fixed piping from this flange to the sludge discharge point and an

electrically actuated sludge valve to control the sludge flow. MRI will control the opening/closing of this valve.

Drive Unit:

Each Cable–VacTM unit will have a drive which will move the header assembly by means of a 1/4” stainless steel cable. The drive unit contains a VFD controlled 1/4 HP AC Motor & Gearbox

Basin dimension (L,W,D): 40 ft x 25 ft x 15 ft (SWD) Collectors per basin: 1

Dimensions of sludge collector: 40 ft x 25 ft Sludge flow per collector: 150-200 gpm

Solids removal concentration: 0.5-1.5%

Head loss through system: 2.5 ft (estimated)


Tel (303) 279-8373 Fax (303) 279-8429

5

and is mounted on the concrete wall or walkway at either end of the basin. All mounting hardware and drive covers are included. All underwater cable sheaves and brackets are included.

Basic Control System:

The control panel to operate the new units shall be located at the plant operator’s discretion. There will be one control panel to control all units. 120 VAC power shall be required to the

location of each control panel. A ¾ inch conduit shall be required to be run from the control panel to the drive locations and the valve locations.

MRI control panels are designed to control the operation, monitoring and reporting the MRI Hoseless sludge collectors. These panels can be incorporated into the plant controls via

communication through Ethernet communications through a RJ 45 connection allowing operation, monitoring and reporting to the plant SCADA.

Each control panel shall be equipped with the following:

NEMA-12 Aluminum control housing

Allen Bradley MicroLogix 1100 Programmable Logic Controller (PLC)

Allen Bradley PanelView HMI Touch Screen Terminal (6”)

Unmanaged Ethernet Switch (5-8 Port)

Allen Bradley Powerflex Variable Frequency Drive (VFD’s)

Internal DC Power Supply (120VAC to 24VDC)

Main Line Surge Protectors (for 480VAC & 120VAC)

Protective Circuit Breakers (AC only)

The control panels will have the following control options: Hand/Off/Auto

Hand - The unit(s) can be operated from the panel location. All signals from a master control center will be ignored

Off - the unit will not operate at all Auto - The unit(s) will be started and stopped from the master control center

Manual start (Hand) Manual Start – Initiates run cycle

Alarm Reset Alarm Reset – Indicates alarm condition and resets alarm

Travel Speed

Travel Speed – Selects Slow/Med/Fast travel speeds The use of certain PLC’s may add extra cost to the sludge collectors.


Tel (303) 279-8373 Fax (303) 279-8429

6

Technical Documents:

A complete set of technical submittals along with installation instructions and O&M Manuals will be included.

Warranty:

All of MRI equipment is warranted against defects in material and workmanship for a period of 12 months after the equipment is put into service.

Installation Inspection and Start-up:

This proposal includes job site visits, by a factory representative for the purpose of installation inspection and mechanical start-up of each unit.

Schedule:

Technical Submittals: 10-12 weeks from receipt of Purchase Order. Equipment Delivery: 16-18 weeks from approved submittals.

This quotation does not include any items other than those specifically listed above. This quotation does not include Federal, State or Local taxes, permits, duties or fees. All MRI

equipment is protected by patents foreign and domestic, issued and pending.

This proposal is valid for a period of 90 days. BUDGET PRICE FOR (2) 3-stage HPW FLOCCULATOR SYSTEMS: $175,000.00

BUDGET PRICE FOR (2) 3 MGD PLATE SETTLER SYSTEMS: $310,000.00

BUDGET PRICE FOR (2) HOSELESS SLUDGE COLLECTORS: $84,000.00

FOB jobsite is included.

Signed: Chris Hanson Meurer Research, Inc.

1QR-00-085B

EngineerCRW Engineers

Represented byJohn SimonGoble Sampson AssociatesIssaquah, Washington(425) [email protected]

Furnished byAdrian [email protected]

SitkaAlaska

WesTech Opportunity Number: 1830044Tuesday, February 06, 2018

Proposal No. 1830044

Item A – TRIDENT® HS Unit

Technical DescriptionThe Trident® HS system combines tube settlers, Adsorption Clarification and mixed media filtration in asingle package treatment system. Raw water is mixed with recirculated sludge and chemicallyconditioned before being sent to the tube settler section. The tube settler section removes gross solids.Operating in an enhanced coagulation mode, this section provides excellent TOC removal as well asproviding good treatment for low quality or flashy waters. Settled sludge is recirculated back to the rawwater to build large, fast settling particles and optimize chemical usage. Partially clarified water is thensent to the Adsorption Clarifier stage, where particles that do not easily settle are removed. The waterthen flows by gravity to a mixed media filter, where small particulates are removed. An optional UVdisinfection system inactivates pathogens prior to discharge.

Key Features and BenefitsMulti-barrier system provides consistently excellent waterquality.Superlative performance on low quality and flashy waters.High rate system minimizes footprint.Package treatment system reduces construction time andcost.

Design CriteriaModel 1-1/2 HS-2800Number of Units 3Tank Dimensions 47 ft 9 in Length x 15 ft 0 in Width x 10 ft 1 in HeightTrident HS Design Flow 4,200 gpm (6 MGD)Trident HS Design Flow per Unit 1,400 gpm (2 MGD)Tube Settler Loading Rate 5 gpm/ft2

Adsorption Clarifier Loading Rate 15 gpm/ft2

Mixed Media Filter Loading Rate 5 gpm/ft2

Backwash Method Air & WaterMaterial of Construction Carbon Steel


The following budget pricing includes:Tanks finish painted inside and primed on the exterior, bare metal on the bottom. Tube settlers, sludgeremoval drive and header, sludge recirculation pump, and clarifier transfer pump. Pumps include VFDcontroller with integral motor starter. Adsorption Clarifier® system MMAC media and retaining screen.MULTIBLOCK® underdrains with Laser Shield™ media retainer, Mixed Media, MULTIWASH® mediaretaining baffles on filter washtrough. One skid mounted coagulant feed package. Two skid mountedpolyelectrolyte feed packages. Influent, inter-clarifier and filter turbidimeters. Two air wash blowers.Automatic and manual valves. Static mixer for combined influent flow. Magnetic flow meters forinfluent, sludge recirculation and backwash. Ultrasonic level transmitters for tube clarifier and filter.Compressed air system including air dryer and motor starter. Control system with master and localpanels. Programmable Logic Controller (PLC) is included for controlling operating and cleaning cycles.Programming includes AQUARITROL® III chemical dosage control system. Freight to the jobsite andstartup service.

This proposal has been reviewed and is approved for issue by Mike Stotzer on February 6, 2018.


Item B – Trident® Packaged Treatment System

Technical DescriptionThe Trident Packaged Treatment System combines a unique upflow Adsorption Clarifier® section with adownflow mixed media filter bed for high rate water treatment. The Adsorption Clarifier systemincludes a buoyant media for increased capture of contaminants with ease of flushing from the system.The mixed media filter combines different sized filter materials to capture decreasing sized particlesthrough the depth of the filter bed. This package design provides reduced footprint and lower capitalcosts from conventional systems. The Trident system is capable of removing turbidity, suspended solids,color, iron, manganese, odor, taste and parasites such as Giardia lamblia and Cryptosporidium. TheAQUARITROL® automatic process controller automatically adjusts chemical feed rates to changing waterquality to dose the proper amount of chemicals. All materials in contact with potable water are NSF 61approved. The system is modular for easy expansion for future needs.

Key Features and BenefitsReduces capital costs and footprints by using high rate,packaged treatmentSimplifies operator interface with automatic controlRemoves the bulk of contaminants in the adsorption clarifier toincrease filter run timeOptimizes chemical dosing by the AQUARITROL automaticprocess controllerEases future expansion with modular design

Design CriteriaModel 1-1/2 TR-840ANumber of Units 3Dimensions 39 ft 10 in Length x 11 ft 11 in Width x 10 ft 1 in

HeightTrident Design Flow 4,200 gpmTrident Design Flow per Unit 1,400 gpmAdsorption Clarifier Loading Rate 15 gpm/ft2

Design Filter Loading Rate 5 gpm/ft2

Backwash Method Air & WaterMaterial of Construction Carbon Steel


The following budget pricing includes:Painted steel tanks with all necessary tank internals including, Adsorption Clarifier buoyant media,MULTIBLOCK® underdrain with Laser Shield™ media retainer, and mixed media filter materials. Also, thesystem includes inlet flow control with adjustable setpoint, pneumatically operated butterfly valves, twochemical feed packages (normally alum and polyelectrolyte), the AQUARITROL automatic processcontrol PLC program, effluent turbidimeter, two air blowers, and PLC control system, freight to thejobsite, and startup.

This proposal has been reviewed and is approved for issue by Mike Stotzer on February 6, 2018.


Budget PricingProposal Name: Sitka, AlaskaProposal Number: 1830044Tuesday, February 06, 2018

1. Bidder's Contact InformationCompany Name WesTech Engineering, Inc.Contact Name Adrian WilliamsPhone 801.265.1000Email [email protected]: Number/Street 3665 S West TempleAddress: City, State, Zip Salt Lake City, UT 84115

2. PricingCurrency US DollarsScope of SupplyA TRIDENT® HS Unit $2,070,000B Trident® Packaged Treatment System $1,078,000C Stand Alone SuperSettler™ Model DRH-3120 $2,300,000

Taxes (sales, use, VAT, IVA, IGV, duties, import fees, etc.) Not IncludedPrices are for a period not to exceed 30 days from date of proposal.

Field ServiceDaily Rate $960Prices do not include field service unless noted, but it is available at the daily rate plus expenses. The customer will be charged for a minimumof three days for time at the jobsite. Travel will be billed at the daily rate. Any canceled charges due to the customer's request will be addedto the invoice. The greater of visa procurement time or a two week notice is required prior to trip departure date.

3. Payment Terms Submittals Approved 15% Release for Fabrication 35% Net 30 days from Shipment 50%All payments are net 30 days. Partial shipments are allowed. Other terms per WesTech proforma invoice.

4. Schedule Submittals, after PO receipt 6 to 8 Weeks Customer Review Period 2 weeks Ready to Ship, after Submittal Approval 18 to 20 weeks

Total Weeks from PO to Shipment 26 to 30 weeks


Terms & Conditions: This proposal, including all terms and conditions contained herein, shall become part of any resultingcontract or purchase order. Changes to any terms and conditions, including but not limited to submittal and shipment days,payment terms, and escalation clause shall be negotiated at order placement, otherwise the proposal terms and conditionscontained herein shall apply.

Freight: Prices quoted are F.O.B. shipping point with freight allowed to a readily accessible location nearest to jobsite. All claimsfor damage or loss in shipment shall be initiated by purchaser.

Paint: If your equipment has paint included in the price, please take note to the following. Primer paints are designed toprovide only a minimal protection from the time of application (usually for a period not to exceed 30 days). Therefore, it isimperative that the finish coat be applied within 30 days of shipment on all shop primed surfaces. Without the protection ofthe final coatings, primer degradation may occur after this period, which in turn may require renewed surface preparation andcoating. If it is impractical or impossible to coat primed surfaces within the suggested time frame, WesTech stronglyrecommends the supply of bare metal, with surface preparation and coating performed in the field. All field surfacepreparation, field paint, touch-up, and repair to shop painted surfaces are not by WesTech.

Trident® HSMulti-Barrier Package Water Treatment System

The Trident® HS Package Water Treatment SystemThe Trident HS package treatment system provides multi-barrier protection for difficult-to-treat surface water, groundwater, industrial process water, and tertiary wastewater. The multi-barrier design of the Trident HS pack-age consists of high-rate settling, adsorption clarification, and mixed media filtration.

Individually and collectively, the multiple treatment stages of the Trident HS system maintain superior effluent performance. The multi-barrier process is extremely well-suited for:

Water sources with: • High turbidity and color • “Flashy” rivers and streams • Reduction of High TOC/DBP precursors • Cold waters

Tertiary treatment in: • Water reclamation • Phosphorus removal

Trident HS Design Criteria

RawWater

FinishWater

Turbidity (NTU) < 400 < 0.1

True Color (Pt-Co Units) < 100 < 5

Combined Turbidity + Color

< 400

Iron & Manganese (mg/L) < 10 < 0.3 / 0.05

TOC (mg/L) 50 - 70%Removal

Phosphorus (mg/L) < 5 < 0.1

Stage 1 - Chemical Conditioning / Tube Settling Before water enters the treatment unit, coagulant and polymer are added to begin the coagulation and flocculation process. A sludge recycle flow is introduced near the coagulation point to aid in floc formation. This recycle flow also serves to maintain a steady-state solids concentration, minimizing variations in influent solids concentration.

For plants incorporating enhanced coagulation, the tube clarification stage reduces influent solids concentration prior to the Adsorption Clarifier® stage, leaving the majority of coagulated particles in the tube settler clarifier. For cold water conditions, the tube clarifier provides added detention time.

Stage 2 - Enhanced ClarificationA combined bed of both compressible and buoyant bead adsorption media provides second-stage clarification. The Adsorption Clarifier media further reduces solids prior to filtration. Captured solids are periodically flushed from the clarifier using an air/water combination. Tube-clarified water is used for the flushing process.

Stage 3 - Mixed Media FiltrationMixed media filtration removes the remaining solids using a bed of anthracite, sand, and high-density garnet supported by a direct retention underdrain. For improved filtration, the media surface area per volume increases from top to bottom and the backwashing process incorporates simultaneous air /water backwashing and baffled washtroughs to prevent media loss and assure clean media.

Trident HS Process Flow Diagram

Multi-Barrier Protection

Complete Package Plant

Tube Clarification The tube clarifiers reduce plant waste volume and improve organics removal. The tube clarifier module can also be retrofitted to existing packaged clarifica-tion and filtration systems to improve process performance and reduce waste.

Adsorption Clarifier SystemThe unique design of the Adsorption Clarifier eliminates the need for settleable floc formation. Therefore, floc size and settling time are not factors. Because of this, Trident systems, as a whole, use significantly less coagulant and polymer than conventional settling clarifiers. The buoyant media is rolled and scarified to greatly improve particulate removal. The compressible fiber media is used to capture more solids. The buoyant and compressible fiber media are NSF-61 certified and typically will last the life of the system.

Mixed Media Filtration and MULTIWASH® BafflingThis Microfloc™ pioneered mixed media technology has become the industry standard for filtration. By using three or more granular materials of differing size and specific gravity, the progressive coarse-to-fine mixed media produc-es superior quality finished water. MULTIWASH baffles retain media during the simultaneous air/water backwash process which produces unmatched backwashing capabilities for the Trident HS system.

MULTIBLOCK® Underdrain with Laser Shield™

MULTIBLOCK underdrains offer the proven effectiveness of compensating dual lateral underdrain technology, which evenly collects filtered water. The MULTIBLOCK compensating orifice design also uniformly distributes backwash water and air to keep filters running at peak performance.

At less than one-tenth of an inch thick, the Laser Shield design reduces underdrain surface area per filter area by as much as 200 times when compared to porous bead designs, thus minimizing fouling potential.

Ultrasonic Level Transmitter

MULTIWASH Baffle

Backwash Supply

FilteredWater

Filter to Waste

Air Wash Supply

MULTIBLOCK Underdriain

Flush and Backwash Wastewater

Sludge Recycle

Static Mixer

Raw Water

Sludge Removal Drive Unit

Adsorption Clarifier with Buoyant Bead and Compressible Fiber Media

Tube Settler Clarifier

Anthracite Silica SandGarnet

Trident HS EfficienciesSpace Efficient

• The package design of the Trident HS system significantly reduces space between different treatment processes in your flow sheet, thus reducing floor space required.

• Operates at higher hydraulic loading rates than conventional systems.

Chemically Efficient• The Aquaritrol® III process controller uses inlet and outlet turbidity signals to automatically adjust

chemical dosage. This results in a more efficient use of chemicals than a simple flow pacing.• Keeps previously-reacted solids in the system to build floc in incoming water.• Keeps a high solids inventory in the tube settler to compensate for sudden changes in raw water.• Reuses partially-reacted chemicals.

Waste Efficient• MULTIWASH systems provide a sustained air/water backwash at high rates, resulting in a vigorous

backwash unmatched in the market.• Proprietary MULTIWASH troughs retain media in the system.• Can offer cleanliness and media-loss prevention guarantees.• Tube settler leads to longer duration between Adsorption Clarifier flush sequences, reducing waste.• Combined tube settler sludge blowdown, Adsorption Clarifier flush, and MULTIWASH backwash will

generally be <5% total waste.

Trident HS System Turbidity Performance

Tu

rbid

ity

(NTU

)

Time in Hours

Raw Water

Tube Clarifier EffluentClarifier Flush

Adsorption Clarifier® Effluent

Filtered Water

Trident HS Standard Sizes

Getting the Right Fit

Standard Components

Epoxy-coated steel tank

Media

Internals

Actuated and manual valves

Inlet magnetic flow meter

Pressure transmitters

Ultrasonic level transmitter

Turbidimeters

Automated PLC controls

Backwash magnetic flow meter and control valve

Blower package

Transfer pump

Recirculation pump

Chemical feed packages (coagulant and polymer)

Optional Components

Integrated plant PLC controls package

Air compressor package

Interconnecting walkways and platforms

Aluminum or stainless steel tanks

Streaming current monitor

Trident HS Tank Sizes

Model Length Width Height Flow/Tank

HS - 700 21’ 6” 9’ 0” 10’ 0” 350 gpm

HS - 1050 25’ 7” 11’ 0” 10’ 0” 525 gpm

HS - 1400 30’ 10” 12’ 0” 10’ 0” 700 gpm

HS - 2100 36’ 1” 15’ 0” 10’ 0” 1,050 gpm

HS - 2800 47’ 9” 15’ 0” 10’ 0” 1,400 gpm

Stretched models are available for applications that require larger filtration areas.

Trident HS Pilot and Lab WorkTrident HS package treatment pilots are available for onsite test work and can be used in a variety of treatment applications. Pilot testing may follow bench-scale testing as the final step in determining full-scale design and projected performance. WesTech’s fully equipped sedimentation/filtration lab performs testing of site-sourced water samples to help determine the appropriate treatment for any given water.

© WesTech Engineering Inc. 2016

Tel: [email protected] Salt Lake City, Utah, USA

Represented by:

Trident®Package Water Treatment System

The Trident® PackageWater Treatment System

Surface Water Treatment • Turbidity reduction • Color removal • Reduction of high TOC/DBP precursors

Groundwater Treatment • Iron and manganese removal • Arsenic • Groundwater under the influence of surface water

Tertiary Treatment • Water reuse • Phosphorus removal

Industrial Process Water

Trident Design Criteria

RawWater

FinishWater

Turbidity (NTU) < 75 < 0.1

True Color (Pt-Co Units) < 35 < 5

Combined Turbidity + Color

< 75

Iron & Manganese (mg/L) < 10 < 0.3 / 0.05

Proven and Efficient

The treatment process is started when chemically dosed raw water enters the Adsorption Clarifier near the bottom of the tank where an upflow treatment process combines flocculation and clarification. From the Adsorption Clarifier, flow continues over a weir into the collection trough where it is distributed into the mixed media filtration chamber, after which it is collected by the MULTIBLOCK® underdrain with Laser Shield™ media retainer and exits the tank.

Raw Water

Filtrate

Filtration Mode

Air

Wastewater

Backwash Water

No Flow

Media Expansion

Backwash Mode

Like the Adsorption Clarifier flush, the backwash cycle is initiated when dirty bed headloss is reached in the mixed media filter section. The Trident inlet and outlet valves are closed and the air scour valve is opened to allow an air scour cycle. Solids from the backwash are then removed by water flowing up into the collection trough and discharged out through the waste pipe. A filter-to-waste sequence follows to ripen the filter media before returning the unit to service.

Air Scour and Water Flush

Air

Raw Water

Wastewater

No Flow

Media Expansion

Buoyant Media Flush Mode

The Adsorption Clarifier is engineered to automatically initiate a flush cycle once headloss indicates that cleaning is required. When the cleaning is initiated, the waste gate and air scour valves are opened as raw water continues to flow. The air/water flush aggressively separates and removes the solids from the media. Solids are then discharged out through the waste pipe.

When MicroflocTM products first introduced the Trident technology, it represented a significant advancement in water and wastewater treatment for plant owners and operators. Not only did it remove turbidity, suspended solids, color, iron, manganese, odor, taste, and pathogens such as Giardia lamblia and Cryptosporidium, but it did so at a lower capital cost than conventional systems, in a smaller space, and at higher flow rates per unit area.

Today, more than 800 Trident technology systems, large and small, are at work all across North America and the world. Our Trident systems continue to evolve as we constantly strive to find ways to produce even higher quality treated water at higher flow rates per unit area and further reduce installation and operating costs.

The Trident water treatment system utilizes a two-stage configuration consisting of an up-flow buoyant bead and compressible media Adsorption Clarifier® system followed by a conventional down-flow mixed media filter to produce high quality water.

Complete Package Plant

Trident Process Flow Diagram

Optional Soda Ash

Optional Chlorine

Coagulant Polymer

OptionalStatic Mixer

Air

Backwash Supply

Flush/Backwash Waste

Filter to Waste

Inlet Filtrate

Silica Sand

Ultrasonic Level Transmitter

Effluent Turbidimeter

Media Retention Screen

Air Manifold

Air Supply

Headloss/Pressure Switches

Influent Water Manifold

Backwash Supply

Epoxy-Coated Steel Tank

Waste Gate

Standard Components

Epoxy-coated steel tanks

Media

Internals

Actuated and manual valves

Inlet magnetic flow meter

Pressure transmitters

Ultrasonic level transmitter

Effluent turbidimeter

Automated PLC controls

Backwash control valves

Blower package

Chemical feed packages (coagulant and polymer)

Optional Components

Air compressor package

Integrated plant PLC controls package

Backwash magnetic flow meter

Interconnecting walkways and platforms

Aluminum or stainless steel tanks

Inlet turbidimeter

pH monitor

Streaming current monitor

Static mixerAdsorption Clarifier SystemTrident systems use less coagulant and polymer than conventional settling type clarifiers. Within the Adsorption Clarifier system it is not necessary to form a settleable floc, which means floc size and settling time are not factors. The buoyant media is rolled and scarified to greatly improve particulate removal. The compressible fiber media is used to capture more solids. Both the buoyant and compressible fiber media are NSF-61 certified and typically will last the life of the system.

Mixed Media Filtration Microfloc pioneered mixed media technology has become the industry filtra-tion standard. By using three or more granular materials of differing size and specific gravity, the progressive coarse-to-fine mixed media produces superior quality finished water.

MULTIBLOCK Underdrain

Adsorption Clarifierwith Buoyant Bead and Compressible Fiber Media

Garnet

Inlet Inlet FlowMeter

Filter to Waste Effluent

Anthracite

Standard Sizes

Highly Efficient, Simple Operation

Get More with MicroflocTri-Mite: Big Performance in a Small Water Treatment SystemFor lower flows, Microfloc offers the Tri-Mite® package water treatment plant. Using the same process as the Trident system, the Tri-Mite comes factory-assembled with pumps, controls, piping, valves, and an air scour blower mounted on the tank. These items are pre-plumbed and wired for simple, fast installation.

The Tri-Mite unit is available in five standard sizes as single units from 50 gpm to 350 gpm and as a two-unit system up to 700 gpm capacity. For flows less than 50 gpm, a single unit can be operated on an intermittent or reduced flow basis. These systems are perfect for new designs with future expansion in mind. The future additional tank would share the control panel, blower, and backwash pump of the first tank.

Equipment Upgrades and Expansions If your unit is more than 10 years old, or has seen changes in raw water quality, it may be worthwhile to inquire about upgrading your Trident system. Common upgrades include enhanced PLC control systems, underdrain replacement accompanied with backwash upgrade, Trident HSR integrated presedimentation systems, and replacement of up-flow media. Retrofits are also available for other package treatment systems.

Stretch CustomizationSome regulatory requirements may dictate a lower hydraulic loading through the filter cell. This is a simple change for the Trident system. An optional stretch filter cell is available to lower the hydraulic loading rate from 5 gpm/ft2 to 4 gpm/ft2. Other filter loading rates may also be achieved through custom design.

MULTIBLOCKMULTIBLOCK underdrains provide a high-quality, low-cost, engineered product that is economical and versatile. MULTIBLOCK underdrains are fitted with the unique Laser Shield media retaining system that eliminates the need for support gravel. Combined air and water backwash is provided using this system.

• Reduced profile underdrain • Superior media retention capability

• Uniform distribution of water and air backwash • NSF-61 approved • Resistant to plugging and fouling

Trident Process Controller Including the AQUARITROL® IIITrident package treatment units are supplied with fully automated programmable logic controls (PLC). These controls allow plant personnel to easily monitor operational parameters and control all treatment equipment and processes. Changes in raw water characteristics and flow rate are automatically detected by the AQUARITROL III program. This PLC-based, feed-forward, loop control system monitors the filter effluent quality and continually evaluates and regulates influent chemical feed to maintain desired effluent water quality parameters. The operator sets an adjustable effluent quality setpoint and the Trident controls, utilizing the AQUARITROL III program, do the rest. WesTech’s electrical engineers and programmers can also integrate new whole plant operation or existing plant instruments into the Trident PLC controls. Complicated plant expansions are simplified by providing seamless integration of new and existing equipment.

• Optimized and flexible process controls • Chemical usage is maximized while maintaining

performance

Tri-Mite TridentInfluent Flow Rate GPM 50 75 100 175 350 175 350 700 1400

Tank Dimensions (Shipping)

Length 9 ft 0 in 9ft 2 in 11 ft 2 in 13 ft 9 in 23 ft 2 in 10 ft 1 in 14 ft 6 in 27 ft 10 in 39 ft 10 in

Width 5 ft 8 in 7 ft 10 in 7 ft 8 in 9 ft 11 in 10 ft 2 in 6 ft 11 in 8 ft 11 in 8 ft 11 in 11 ft 11 in

Height 8 ft 5 in 8 ft 6 in 8 ft 6 in 8 ft 2 in 8 ft 3 in 8 ft 5 in 8 ft 5 in 8 ft 5 in 10 ft 1 in

Weights Shipping (lbs) 6,300 8,100 9,600 9,200 14,600 7,000 10,250 17,000 34,000

Operating (lbs) 14,000 20,000 25,000 43,000 78,000 35,000 70,000 140,000 330,000

Tank Connections Influent 2 in 3 in 3 in 4 in 6 in 4 in 6 in 8 in 12 in

Effluent 2 in 3 in 3 in 4 in 6 in 6 in 8 in 12 in 16 in

Backwash Supply 3 in 4 in 4 in 5 in 8 in 6 in 8 in 12 in 16 in

Waste/Overflow 4 in 6 in 6 in 8 in 10 in 8 in 10 in 14 in 20 in

Air Wash (Clarifier) 1.5 in 2 in 2 in 2 in 3 in 2 in 3 in 4 in 6 in

Air Wash (Filter) 1.5 in 2 in 2 in 2 in 3 in 3 in 4 in 6 in 8 in

Waste Production Flushing Flow Rate (gpm)

50 75 100 175 350 175 350 700 1,400

Flushing Volume Per Cycle (gal)

500 750 1,000 1,750 3,500 1,750 3,500 7,000 14,000

Mixed Media Per Cycle (gal)

900 1,350 1,800 3,150 6,300 3,500 7,000 1,4000 28,000

Filter to Waste Per Cycle (gal)

250 375 500 875 1,750 875 1,750 3,500 7,000

© WesTech Engineering, Inc. 2013

Tel: [email protected] Salt Lake City, Utah, USA

Represented by:

1 QR-00-085B

Engineer CRW Engineers Represented by John SImon Goble Sampson Associates Issaquah, Washington (425) 392-0491 [email protected]

Furnished by Adrian Williams [email protected]

Sitka Alaska

WesTech Opportunity Number: 1830044 Tuesday, April 10, 2018


Item A – Clarifier Mechanism WesTech Model Number CLS25

General Scope of Supply Description Unit Dimension/Capacity Number of Clarifiers Each 1 Application - Filter Backwash Clarification Basin Diameter ft 25 Tank Side Water Depth ft 15 Freeboard ft 1

Equipment Description WesTech is a leader in providing proven clarification solutions. The WesTech Clarifier has many superior design, mechanical, and operational features and is a capable option for primary clarification applications.

This WesTech Clarifier is designed for the purpose of continuously separating and removing suspended solids.


Detailed Scope of Supply Item Unit/Size Quantity Description Material Drive Shaft 6" dia. 1 Drive shaft for transmitting torque

from drive to rake arms Steel

Rake Arms 25’ dia. 1 Set Rake arms for moving settled solids to center of tank for removal; includes stainless steel squeegees

Steel

Bridge Full Span 1 Beam style bridge to span tank diameter, provides internal equipment support

Steel

Walkway 36" 1 Includes aluminum I-bar grating and aluminum 2-rail handrail

Steel/Aluminum

Drive Platform min. 24" clearance around drive

1 Includes aluminum deck plate and aluminum 2-rail handrail

Steel/Aluminum

Anchor Bolts and Fasteners

Varies TBD - 304SS

Walkway Bridge The walkway bridge supports the clarifier mechanism and allows access to the center platform and drive unit for equipment maintenance. It includes non-slip flooring and handrails along both sides and around the center platform, with sufficient clearance around the drive for easy maintenance. Rake Arms Rake arms with segmented rake blades effectively move settled solids to the center of the tank for removal.

Drive Unit Description Unit Dimension/Capacity Drive Type Shaft Drive Continuous Torque Rating Ft-lbs 3,125 Peak Torque Ft-lbs 6,250 Rake Motor Characteristics 0.5 HP, 230/460 V, 3 Ph, 60 Hz Alarm Torque 2 adjustable switches for alarm and motor cutout


WesTech drive units are delivered to the job site as a single, completely assembled and shop-tested unit, ready to be installed on the clarifier bridge. The result of a thorough design and meticulous component selection is a strong, reliable, high-quality drive that will provide a long service life with minimum maintenance. Direct Coupling Direct coupling of motor, reducer, and pinion shaft eliminates chain or belt drive transmissions, thus increasing efficiency and operator safety. Electric Motor The electric motor, direct coupled to a speed reducer, rotates the external gear by means of a pinion fastened to the output shaft of the speed reducer. The drive control pointer indicates the torque loading in percentages. The electric motor is totally enclosed, suitable for outdoor service, but other commercially available motors to suit environment or service, such as explosion proof, can be furnished. When required, a variable speed drive can be added to vary the output speed of the drive. This allows optimization of the process, which can result in long term savings. Input Speed Reducer The speed reducer, driven by the motor, is a completely sealed oil or grease lubricated unit. It is of the cycloidal type, which combines extremely high ratios with high efficiency and low wear in a compact unit. Torque transmitting elements roll rather than grinding or sliding, thus achieving efficiencies of 90 percent. Virtually no wear failures have occurred in properly sized WesTech drives. Even after 30 years of operation, many WesTech reducers are still in use. Precision Bearing Advantages Precision Manufacturing Tolerances The bearings utilized are acceptable for high load, high speed applications and are manufactured by recognized bearing companies. The use of these precision bearings is widespread among larger and more heavily loaded clarifier and thickener mechanisms common to the metallurgical industries. Exceptional long life and load capacities Instead of applying the bearing load in four points on the bearing balls as with old-style strip lined bearings, the precision bearing utilizes a full band contact race with hardness equal to that of the strip liners. Calculated bearing life is at least five times that for strip liners of the same ball size and diameter. The need for splitting gears and housings is eliminated because of the superior service life.


Overturning Load Capacity Strip lined bearings have no inherent overturning load capacity and must rely on the mechanism weight alone to hold the bearing race together. This capacity of the precision bearing makes possible tank settling, misalignment, and lack of precision leveling of the drive during installation and operation a far less determining factor in premature bearing failure. Main Bearing Protection WesTech gear housings protect from dirt and contamination using designed neoprene seals and gaskets, whereas strip lined bearings can only use a loose felt seal. WesTech precision gears also allow the bearing to run in a separate sealed grease cavity, which achieves additional protection from contamination.

Paint Coating Area Sandblast

SSPC Paint Type Brand Product # Total DFT Coats

Submerged Coating

SSPC-SP10 / NACE 2

Epoxy Tnemec N140-1255 4-6 mils 1, finish by others

Non-Submerged

SSPC-SP6 / NACE 3


Drive First Coat

SSPC-SP6 / NACE 3

Epoxy Tnemec N140F-1255

3-9 mils 1

Drive Unit Polyurethane Enamel

Tnemec 1074U-B5712

2-5 mils 1

Controls & Instrumentation Description Type Notes Control Panel Type NEMA 4X 304SS With door mounted operators and status lights. One (1)

magnetic combination motor starter, with internally reset thermal overloads, fail safe relays, terminal blocks, timers, repeat cycle timers, fuse and fuse blocks and other supporting hardware is provided. A control power transformer will provide 120 VAC for internal controls. The transformer will have both primary legs and one secondary leg fused.

WesTech Trips to the Site Number of Trips

Number of Days Includes

2 4 Installation inspection, startup, instruction of plant personnel, and observation of torque testing


Clarification and Comments • Effluent collection by floating box decanter in the following section.

• Tank is not included at this time, current design is based on a concrete tank by others. WesTech can include a steel tank upon request.

Note: Any Item Not Listed Above to Be Furnished by Others. Items Not by WesTech Electrical wiring, conduit, or electrical equipment, piping, valves, or fittings, shimming material, lubricating oil or grease, shop or field painting, field welding, erection, assembly of component handrail, detail shop fabrication drawings, performance testing, bonds, unloading, storage, concrete work, or field service (except as specifically noted). This proposal has been reviewed and is approved for issue by Brett Boissevain on April 10, 2018.


Item B – Box Decanter WesTech Model Number DEF33R

General Scope of Supply Description Unit Dimension/Capacity Number of Decanters each 1 Application - Filter Backwash Decanting Basin Diameter ft 25 Side Water Depth ft 15 Decant Flow Rate gpm 37.5 Decant Range feet 9

Equipment Description A decanter allows the backwash water clarification basin to act as an equalization basin as well. The floating decanter will remain near the top of the surface, removing water below the surface to avoid any floating material. The box decanter uses a truss type cage as a travel guide, allowing for stops to limit the floating box travel. The unique floating decant mechanism rises and falls with the water level as backwash volume changes.

Detailed Scope of Supply Item Unit/Size Description Material Box Decanter 2.5’ square x 2.5”

(minimum) Includes submerged orifices for clarified water draw off, pipe strap, bar, and brackets

Steel

Discharge Hose 2.5” diameter Flexible, reinforced hose Rubber Floats Foam core floats FRP Float Supports Float supports Steel Guide Rails 6”, 40 (dia., sch.) Float box guide rails Steel Anchor Bolts and Fasteners

Steel

Paint Coating Area Sandblast

SSPC Paint Type Brand Product # Total DFT Coats

Submerged Coating

SSPC-SP10 / NACE 2


Non-Submerged

SSPC-SP6 / NACE 3


WesTech Trips to the Site Number of Trips Number of Days Includes 1 2 Installation inspection, startup, and instruction of plant

personnel.


Note: Any Item Not Listed Above to Be Furnished by Others. Items Not by WesTech Electrical wiring, conduit, or electrical equipment, piping, valves, or fittings, shimming material, lubricating oil or grease, shop or field painting, field welding, erection, assembly of component handrail, detail shop fabrication drawings, performance testing, bonds, unloading, storage, concrete work, or field service (except as specifically noted). This proposal has been reviewed and is approved for issue by Brett Boissevain on April 10, 2018.


Budget Pricing Proposal Name: Sitka, Alaska Proposal Number: 1830044 Tuesday, April 10, 2018

1. Bidder's Contact Information Company Name WesTech Engineering, Inc. Contact Name Adrian Williams Phone 801.265.1000 Email [email protected] Address: Number/Street 3665 S West Temple Address: City, State, Zip Salt Lake City, UT 84115

2. Pricing

Currency US Dollars Scope of Supply A Clarifier Mechanism WesTech Model Number CLS25 $130,000

B ox Decanter WesTech Model Number DEF33R $55,000

Taxes (sales, use, VAT, IVA, IGV, duties, import fees, etc.) Not Included Prices are for a period not to exceed 30 days from date of proposal.

Field Service Daily Rate $1,200 Prices do not include field service unless noted, but it is available at the daily rate plus expenses. The customer will be charged for a minimum of three days for time at the jobsite. Travel will be billed at the daily rate. Any canceled charges due to the customer's request will be added to the invoice. The greater of visa procurement time or a two week notice is required prior to trip departure date.

3. Payment Terms

Submittals Approved 15%

Release for Fabrication 35%

Net 30 days from Shipment 50% All payments are net 30 days. Partial shipments are allowed. Other terms per WesTech proforma invoice.

4. Schedule

Submittals, after PO receipt 6 to 8 Weeks

Customer Review Period 2 weeks

Ready to Ship, after Submittal Approval 18 to 20 weeks

Total Weeks from PO to Shipment 26 to 30 weeks


Terms & Conditions: This proposal, including all terms and conditions contained herein, shall become part of any resulting contract or purchase order. Changes to any terms and conditions, including but not limited to submittal and shipment days, payment terms, and escalation clause shall be negotiated at order placement, otherwise the proposal terms and conditions contained herein shall apply. Freight: Prices quoted are F.O.B. shipping point with freight allowed to a readily accessible location nearest to jobsite. All claims for damage or loss in shipment shall be initiated by purchaser. Paint: If your equipment has paint included in the price, please take note to the following. Primer paints are designed to provide only a minimal protection from the time of application (usually for a period not to exceed 30 days). Therefore, it is imperative that the finish coat be applied within 30 days of shipment on all shop primed surfaces. Without the protection of the final coatings, primer degradation may occur after this period, which in turn may require renewed surface preparation and coating. If it is impractical or impossible to coat primed surfaces within the suggested time frame, WesTech strongly recommends the supply of bare metal, with surface preparation and coating performed in the field. All field surface preparation, field paint, touch-up, and repair to shop painted surfaces are not by WesTech.

Pall Corporation Budgetary Proposal

Pall ARIATM

Membrane Filtration System

City and Borough of Sitka Alaska: 5.62MGD

12/20/2017 Proposal #: OPP1015938-0-B

Pall Budgetary Proposal 12/20/2017 Page 2 of 12

Submitted to: CRW Engineering Rebecca Venot

Submitted by: Pall Water: Lance Gannon West Regional Sales (607) 591-0077 [email protected] Goble Sampson: John Simon [email protected] (425) 736 4584

mailto:[email protected]



PROPRIETARY & CONFIDENTIAL INFORMATION NOTICE

This proposal document is proprietary to Pall Corporation and is furnished in confidence solely for use in evaluating the proposal and for no other direct or indirect use. No rights are granted to the recipient for any information disclosed in this proposal. It contains proprietary information which may be the subject of an issued patent or pending application in the United States or elsewhere. By accepting this document from Pall Corporation the recipient agrees:

• to use this document and the information it contains exclusively for the above-stated purpose and to avoid use of the information for performance of the proposed work by recipient itself or any third party.

• to avoid publication or other disclosure of this document or the information it contains to any third party without the prior approval of Pall Corporation.

• to make only those copies needed for recipient's internal review, and

• to return this document and any copies thereof when they are no longer needed for the purpose for which furnished or upon the request of Pall Corporation.


Table of Contents

1. Pall Offering 1.1 Scope Summary 1.2 Pricing Summary 1.3 Delivery Schedule 1.4 Terms and Conditions

2. Scope of Supply

2.1 Scope Summary Table 2.2 Equipment Description 2.3 Submittal Description 2.4 Services and Labor

3. Technical Summary

3.1 Process Summary 3.2 Treated Water Objectives 3.3 Operational Parameters 3.4 Acceptance Criteria

The following information can be provided upon request Warranty Overview of Pall Corporation Hollow Fiber Membrane System Overview Pall Standard Terms and Conditions


1

1.1

Pall Offering

Project Summary

We are pleased that the temporary water treatment trailer Pall provided in the past performed well and that City of Sitka is open to partnering with Pall again to improve the treatment capabilities/capacity at the existing plant. Pall is excited to offer the City of Sitka the following: MF Membrane Filtration technology will provide the City with approx. 5.62 MGD treatment capabilities during high turbidity events in the supply. The throughput of the proposed solution package will be based on further due diligence by Pall Water’s Process Engineering team that involves a thorough understanding and assessment of seasonal source water quality conditions as well as asking for the City’s input on the maximum system capacity requirement.

As requested, the proposed system has been designed to treat feed water with high suspended solid/turbidity. With operational and programing modifications, the Pall system can have automated start- stop functions then stored on stand-by till the next feed water upset. The recommended solution features the Pall (3) AP8 “package” water systems with the total number of modules spaces filled (104 per rack). The system consists of a fully integrated, skid mounted valve & module rack, CIP system, required ancillary equipment, install/commissioning support. Upon request, Pall can include both process (operational) and programming support services to integrate the new filtration system into the existing treatment processes (such as flow-pacing post filtration chlorine injection, UV system integration, storage tank level automation, etc). A CIP/washwater neutralization system is included. System redundancy has been excluded from the scope of supply but can be added based on requirements.

Once you have had sufficient time to review our offering, please direct any questions you may have back to myself and our team. Although design aspects and feasibility surrounding this project have not been fully defined, Pall looks forward to partnering up to support this objective. We appreciate the interaction with your team to explore the advantages of the Pall Membrane Filtration System.

1.2 Pricing Summary

Item Description Sale Price (US)

1 AriaTM Membrane Filtration System (Details Per Section 2)

$1,950,000

1.3 Delivery Schedule

The schedule provided is Pall's standard and reflects typical project execution. If requested, we would be happy to review customer schedule requirements and adjust where possible to accommodate project specific needs.

Milestone Typical Schedule

1 Acknowledgement of Purchase Order Typically 1 to 2 weeks after Receipt of Purchase Order

2

Submittals/Shop Drawings

Typically 2 weeks after Acknowledgement of Purchase Order

3

Commence Manufacturing1

Typically 1 - 2 weeks after Submittals/Shop Drawings submitted


4 Equipment Ready to Ship and Preliminary O&M Manual Typically 16 -22 weeks after Commence Manufacturing

5 Installation Completed (by Others) Variable

6 Commissioning Complete/Final Acceptance Approximately 6 weeks after Installation Completed

Note 1: For standard equipment, manufacturing may commence order acknowledgement. The schedule above assumes standard equipment and standard submittals.


1.4 Terms and Conditions

All sales made by Pall are subject to the terms contained within this Section 1.4 and Additional Terms and Conditions of Sale of Systems and Made to Order Goods – The Americas (Available upon request).

Price Validity

This proposal is for discussion purposes only, does not constitute a binding agreement on either party, and remains subject to corporate approval by both parties. The information contained herein is deemed confidential and is not to be shared with any third party.

Shipping Terms

The price does not include shipping costs. Delivery shall be FCA Seller’s Shipping Point, INCOTERMS® 2010.

Payment Terms

Payment of invoiced amounts due to Seller shall be paid Net 30 days and as further defined in Additional Terms and Conditions of Sale Systems and Made to Order Goods – The Americas .

Bonds No bonds of any type are included with this proposal.

Taxes

No taxes are included in the pricing. Payment of all Taxes related to the Goods and Services proposed shall be the exclusive responsibility of the Buyer as further defined in Additional Terms and Conditions of Sale Systems and Made to Order Goods – The Americas .


2

2.1

Scope of Supply

Scope Summary Table

Item Description By PALL By

OTHERS (1) Master Control Panel with Allen Bradley Logix PLC, or equal X Design and supply of systems prior to membrane filtration system. X Feed Tank Included as part of AP Skid X Feed Pump(s) and VFD(s) included as part of AP skid X Feed Strainer included as part of AP Skid X 3 (3 + 0) AP8 Units, each factory assembled and tested unit including valves, instruments & I/O required for operation X

Each AP Unit will include a membrane module rack for on-site assembly and (104) hollow fiber membrane modules X

RF Tank Included as part of AP Skid X RF Pump(s) included as part of AP Skid X

(1) 2500 gallon CIP System factory assembled and tested prior to shipment with valves, instruments, pumps, tank, heater as needed for operation

X

(1) 12500 gallon Neutralization System factory assembled per the P&ID and tested prior to shipment: X

(2) Air Compressors (1) Air Receiver X Chemical Storage Equipment X Supply of any required chemicals X Design and supply of anchor bolts for Pall supplied Equipment X

Receiving, unloading and safe storage of equipment until ready for installation X

Installation of all equipment X Design and supply of interconnecting pipe, inclusive of pipe supports and flexible connectors

X

Motor Control Center (MCC) X All wiring, cabling, and tubing for power supply, signals, communications, and to connections on Pall supplied equipment

X

Design, supply, and installation of all civil infrastructure inclusive of buildings, fire and safety protection, HVAC, walkways, platforms, etc.

X

All Permits X


2.3 Submittal Description The project schedule is based on submittals/shop drawings provided in electronic format via a secure FTP site for information only. This allows work to proceed on the project without a document approval process.

Submittals/Shop Drawings P&ID General Arrangement Drawings for Pall-Supplied Equipment Electrical Interconnect Drawing (Power One-Line, I/O Interconnection, and Network Layout) Electrical Drawings for Pall-Supplied Panels Mechanical Replacement Parts List Electrical Replacement Parts List Compressed Air System Information Installation Manual Cutsheets for Pall-Supplied Off-Skid Components Installation & Startup Checklist Final Submittal (provided at completion of commissioning) Operation and Maintenance Manual Software License Transfer Documentation


2.4 Services and Labor Commissioning & Training time is estimated to be 5 man-weeks. Training activities occur during the commissioning process. Commissioning

Each day shall be considered 8 hours on site. Commissioning will begin once the system is fully installed. A commissioning Checklist is prepared specifically for each project during project execution. Commissioning shall consist of the activities outlined in the project specific Commissioning Checklist. Commissioning activities include: - Confirmation of network communications - Confirmation that I/O is connected to the control system - Confirmation of MF System functionality (components are functioning and control system sequences

are functional) - Startup and tuning of Pall controls

Operator Training

Operator training is estimated to take 1 to 3 days depending on system complexity. Training is provided on-site by a Pall Field Service Engineer. The estimated time assumes that all staff are trained at the same time. Training time will be split between a classroom presentation and hands-on training with the equipment.


3 Technical Summary 3.1 Process Summary Source Description:

Suface water: Indian River or Sawmill Creek (downstream of Blue Lake) Treatment processes prior to Membrane Filtration System

Direct Coagulation up to 10 mg/L of aluminum-based coagulant

Membrane System Feed Water Characteristics

Quality of the water entering the Pall Membrane Filtration System as summarized in table below forms the basis of design for this proposal. In the event that the feed water to the membrane filtration system is outside these parameters the system performance, cleaning protocol, operating parameters, and/or warranties may be affected.

Parameter Units Range Turbidity NTU 0.2-75

TOC ppm Up to 5 Hardness ppm Less than 20 Alkalinity ppm Less than 20

TSS ppm 5-40 Fe ppm <2.0 Mn ppm <1.0

Notes:

1 – Assumed Water Quality is based on typical water quality for similar source waters. The design parameters may change after review of actual source water quality data.

3.2 Treated Water Objectives

The proposed membrane system is designed to achieve the following results given the feed fluid conditions described in Section 3.1 of this proposal and operation of the system in accordance with the operation and maintenance manual.

Net Filtrate Capacity of 5.62 MGD

Turbidity less than 0.10 NTU 95% of the time, below 0.20 NTU at all times.

The membrane system offers a 2.5 Log reduction Giardia

3.3 Operational Parameters

Hollow Fiber Membrane System operational parameters at design

flow Net Filtrate Capacity 5.62 MGD Recovery 95.7% % Instantaneous Flux 40 GFD FM (Backwash) Interval 27 Minutes EFM Interval 1 Day(s) CIP Interval 30 Days


3.4 Acceptance Criteria

The system shall be accepted by the end user upon completion of the following:

1) Completed system commissioning per section 2.4 2) Production of 1st useable effluent

Appendix D

Detailed Cost Estimates

CBS Filtration Evaluation 1

Engineer's Estimate ‐ Sawmill Creek Intake, UV Site ‐ Lot 17, Membrane Filtration

Prepared By: C Meyn

Date: April 2018

ITEM

NO. WORK DESCRIPTION UNIT

TOTAL

QUANT. UNIT PRICE TOTAL COST

1 Intake Structure and Pumps LS 1 $440,000 $440,000

2 Membrane Equipment LS 1 $2,170,000 $2,170,000

3 Backwash Handling & Recycle LS 2 $495,000 $990,000

4 Finished Water Pumps LS 1 $184,000 $184,000

5 Piping and Valves Yard & Building LS 1 $726,000 $726,000

6 Chlorine Equipment LS 1 $110,000 $110,000

7 Pre‐Engineered Metal Building w/Mech & Plumb LS 1 $2,365,000 $2,365,000

8 Electrical & Controls LS 1 $1,048,000 $1,048,000

Subtotal Direct Costs: $8,033,000

Location Adjustment Factor (28%) $2,249,000

Subtotal w/ Location Adjustment: $10,282,000

General Conditions (15%) $1,542,000

Subtotal w/ General Conditions: $11,824,000

Mobilization/Demobilization (10%) $1,182,000

Prime Contractor Overhead (12%) $1,419,000

Prime Contractor Profit (8%) $946,000

Builder's Risk & Gen Liab Ins (1%) $118,000

Payment & Performance Bonds (1.16%) $137,000

Subtotal w/ Prime Markups $15,626,000


Engineer's Estimate ‐ Sawmill Creek Intake, UV Site ‐ Lot 19, Membrane Filtration

Prepared By: C Meyn

Date: April 2018

ITEM


TOTAL



2 Site Development LS 1 $83,000 $83,000




















Engineer's Estimate ‐ Sawmill Creek Intake, UV Site ‐ Lot 17, Granular Filtration

Prepared By: C Meyn

Date: April 2018

ITEM


TOTAL



2 Granular Equipment LS 1 $1,123,000 $1,123,000






8 Electrical & Controls LS 1 $761,000 $761,000






Mobilization/Demobilization (10%) $858,000







Engineer's Estimate ‐ Sawmill Creek Intake, UV Site ‐ Lot 19, Granular Filtration

Prepared By: C Meyn

Date: April 2018

ITEM


TOTAL



2 Site Development LS 1 $83,000 $83,000







9 Electrical & Controls LS 1 $773,000 $773,000






Mobilization/Demobilization (10%) $872,000







Engineer's Estimate ‐ Sawmill Creek Intake, Pulp Mill Site, Membrane Filtration

Prepared By: R Venot

Date: April 2019

ITEM


TOTAL


1 Demolition and site prep LS 1 $524,000 $524,000

2 Intake Structure & Pumps LS 1 $890,000 $890,000



5 Finished Water Pumping LS 1 $184,000 $184,000

6 Piping and Valves Yard & Building LS 1 $1,053,000 $1,053,000


8 Electrical & Controls Coordination LS 1 $1,227,000 $1,227,000








Prime Contractor Profit (8%) $1,107,000




Contingency (30%) $5,490,000

TOTAL CONSTRUCTION COST: $23,790,000


Engineer's Estimate ‐ Sawmill Creek Intake, Pulp Mill Site, Granular Filtration


Date: April 2019

ITEM


TOTAL







6 Piping and Valves Yard & Bldg LS 1 $835,000 $835,000


8 Electrical & Controls Coordination LS 1 $940,000 $940,000












Contingency (30%) $4,203,000

TOTAL CONSTRUCTION COST: $18,213,000


Engineer's Estimate ‐ Indian River, Membrane Filtration

Prepared By: C Meyn

Date: April 2018

ITEM


TOTAL




3 Pretreatment Equipment LS 1 $671,000 $671,000




7 CT Tank LS 1 $635,000 $635,000


9 Pre‐Engineered Metal Building (110'x135') LS 1 $6,450,000 $6,450,000









Prime Contractor Profit (8%) $1,545,000





Engineer's Estimate ‐ Indian River, Granular Filtration

Prepared By: C Meyn

Date: April 2018

ITEM


TOTAL



2 Intake Structure and Pumping LS 1 $400,000 $400,000



5 Piping and Valves Yard and Building LS 1 $640,500 $640,500


7 Pre‐Engineered Metal Building (110'x135') LS 1 $2,297,500 $2,297,500

8 CT Tank LS 1 $635,000 $635,000

9 Electrical & Controls Coordination LS 1 $954,000 $954,000

Subtotal Direct Cost: $7,320,000












O&M Cost Summary


Date: April 2019

Category Granular Filtration Membrane Filtration

Chemical cost $500 $534

Power usage (kWH/day) 606 815

Labor (hrs/startup‐shutdown) 9 6

Labor (hrs daily) 5 5

Daily Operating Cost $900.00 $1,000.00

Startup/Shutdown Cost $2,000.00 $1,700.00

Treatment System Annual O&M Costs

Existing UV Facility 275,000$

Filtration with Penstock Supply 531,000$

Filtration with Sawmill Creek Supply 600,000$


O&M Chemical Costs

Prepared By: C Meyn

Date: April 2018

Membrane Chemicals Cost/day

Caustic $6.96

Citric Acid $21.39

Sodium Bisulfate $4.87

Total $33

Polymer Usage Quantity Unit

PAX XL‐19 1 $/lb

PAX XL‐19 Dose 20 mg/l

Daily water production 3,000,000 gpd

125,000 gph

Chem Unit Weight 9.23 lb per gallon in sol/n

Coagulant pump pumping rate 2 gph

Coagulant used 54 gpd

500.4 lb/day

Coagulant cost 500 $/day


O&M Power Usage

Prepared By: C Meyn

Date: April 2018

Membrane Power Usage Qty (kWH/day) Source

Consumables Allowance 815 Pall 3.75MGD O&M Estimate

Total 815

Granular Power Usage Qty Usage (hr/day) Demand (kWH/day)

Backwash Pump 5 hp 1 1 3.7

Air blower 7.5 hp 1 1 5.6

Filter effluent pump 10 hp 3 24 536.9

Backwash Recycle Pump 10 hp 1 8 59.7

Total 606

SMC Pumping Qty Usage (hr/day) Demand (kWH/day)

1400 gpm (80 ft head) 40 hp 1.5 24 1073.8

Finished Water Pumping Qty Usage (hr/day) Demand (kWH/day)

1400 gpm pump (200 ft head) 125 hp 1.5 24 3355.7

General Building Lights/Heat/Power Qty Usage (hr/day) Demand (kWH/day)

Lights 0.4 W/ft2 4000 8 32.0

Instrumentation/Controls 1 kW 1 24 0.02

Chemical Dosing Pump 0.03 KW 3 24 0.00

Heat 12.5 W/ft2 125000 12 1500.0

Total 1532.0


O&M Labor Hours

Prepared By: C Meyn

Date: April 2018

Membrane Labor Qty (hrs)

Startup 3

Shutdown 3

Total 6

Granular Labor Qty (hrs)

Startup 6

Shutdown 3

Total 9

Regular Operations Qty (hrs)

WTP Daily Walkthrough 2

WTP Daily Report 1

WTP Regular PM 1

Finished Water PS 1

Total 5

SMC Pump Station

WTP Daily Walkthrough 1


Comparison of Filtration to Existing WTP Operations

April 2018

R. Venot

Existing Treatment Facility:

Fund 210 Division 600 Department 610

2017 2080 hours/year budgeted

Labor 72,587.79$ 34.90$

Fringe Benefits 49,650.31$ 23.87$

Total 122,238.10$ 58.77$

Operating Expenses 152,606.59$ Training, power, chemicals, repairs, services,

tools, postage, other

Total Existing 275,000$

New Filtration Facility:

Power 0.12 $/kwh Estimated annual average cost

Labor (fully burdened) 58.77$ /$/hr

Sawmill Creek Supply

Raw Water Pumping 47,033$

Chemicals 182,646$

Treatment Building Power 93,640$

Labor 128,703$

Finished Water Pumping 146,977$

Total 600,000$

Penstock Supply

Chemicals 182,646$

Treatment Building Power 93,640$

Labor 107,252$

Finished Water Pumping 146,977$

Total 531,000$

Appendix E

Geotechnical Reports

JULY 2018

CBS Filtration Evaluation Lot 17 Sitka, Alaska

Geotechnical Report

Contact

Steven Halcomb, [email protected]

3940 Arctic Blvd., Suite 300 Anchorage, AK 99503 p (907) 562.3252 | f (907) 561.2273

Geotechnical Investigation CBS Lot 17

Submitted To:

Ms. Shilo Williams Project Manager City and Borough of Sitka 100 Alice Loop Sitka, Alaska 99835

Submitted By:

CRW Engineering Group, LLC 3940 Arctic Blvd., Suite 300 Anchorage, AK 99503 (907) 562-3252 www.crweng.com

7.11.18

___________________________

Steven Halcomb, P.E., G.E.

Senior Geotechnical Engineer

July 2018 CRW Project Number 21201.02

http://www.crweng.com/

Geotechnical Investigation CRW Engineering Group, LLC CBS Lot 17 Page i July 2018

Table of Contents

1. Introduction ................................................................................................................... 1

2. Site and Project Description ............................................................................................ 2

3. Subsurface Exploration ................................................................................................... 3

3.1 Subsurface Drilling ............................................................................................................................ 3 3.2 Sample Collection ............................................................................................................................. 3 3.3 Soil Lithology ..................................................................................................................................... 4 3.4 Groundwater Levels and Borehole Completion................................................................................ 4

4. Laboratory Testing and Results ....................................................................................... 5

5. Site Conditions ............................................................................................................... 6

5.1 Seismic Considerations ..................................................................................................................... 6 5.2 Groundwater Conditions .................................................................................................................. 6 5.3 Frost Depth and Permafrost ............................................................................................................. 6

6. Geotechnical Engineering Recommendations .................................................................. 8

6.1 Generalized Soil Profile ..................................................................................................................... 8 6.2 Stability Evaluation............................................................................................................................ 9

6.2.1 Slope Instability ............................................................................................................................................ 9 6.2.2 Loss of Bearing Capacity ............................................................................................................................... 9 6.2.3 Liquefaction and Surface Manifestations .................................................................................................... 9

6.3 Liquefaction Mitigation ................................................................................................................... 11 6.4 Foundation Recommendations ....................................................................................................... 12

6.4.1 Bearing Capacity and Settlement ............................................................................................................... 12 6.4.2 Lateral Load Resistance .............................................................................................................................. 12 6.4.3 Uplift Resistance ........................................................................................................................................ 13 6.4.4 Mat Foundation Recommendations .......................................................................................................... 13

6.5 Retaining Walls and Lateral Earth Pressures .................................................................................. 13 6.6 Slope Stability .................................................................................................................................. 14 6.7 Utility Recommendations ............................................................................................................... 14 6.8 Pavement Recommendations ......................................................................................................... 14

7. Construction Recommendations ................................................................................... 15

7.1 Site Preparation .............................................................................................................................. 15 7.2 Fill Placement and Compaction ...................................................................................................... 15

7.2.1 Engineered Fill Placement and Compaction General Requirements ......................................................... 15 7.2.2 Engineered Fill and Compaction ................................................................................................................ 15

7.3 Excavation Slopes ............................................................................................................................ 15 7.4 Drainage and Control of Water ....................................................................................................... 16

8. Limitations and Closure ................................................................................................ 17

9. References ................................................................................................................... 18

Geotechnical Investigation CRW Engineering Group, LLC CBS Lot 17 Page ii July 2018

Tables

Table 1 – Seismic Design Parameters ........................................................................................................... 6 Table 2 – Summary of Groundwater Levels .................................................................................................. 6 Table 3 – Climatic Berg2 Inputs for Sitka ...................................................................................................... 7 Table 4 – Generalized Soil Profile ................................................................................................................. 8

Figures

Figure 1 – Berg2 Analysis output .................................................................................................................. 7 Figure 2 – Lot 17 Drive Penetrometer Test Results ...................................................................................... 9 Figure 3 – Lot 17 Factor of Safety against Liquefaction vs. Depth .............................................................. 10

Appendices

Appendix A – Figures Appendix B – Borehole Logs Appendix C – Site Investigation Photos Appendix D – Laboratory Results Appendix E – Drive Penetrometer Data

List of Acronyms/Abbreviations

ASTM – American Society for Testing and Materials bpf – blows per foot bgs – below ground surface CBS – City and Borough of Sitka CRW – CRW Engineering Group, LLC ft – feet, foot NFS – non-frost susceptible OSHA – Occupational Safety and Health Administration psf – pounds per square foot pcf – pounds per cubic foot SPT – standard penetration test USCS – Unified Soils Classification System WTP – water treatment plant ° - degrees

Geotechnical Investigation CRW Engineering Group, LLC CBS Lot 17 Page 1 July 2018

1. Introduction

CRW Engineering Group, LLC (CRW) is pleased to present this geotechnical data and recommendations report to support the design and construction of a new Critical Secondary Water Supply Water Treatment Plant (WTP) in Sitka, Alaska. A geotechnical investigation was conducted by CRW for the City and Borough of Sitka (CBS).

The scope of work included:

Performing a geotechnical investigation on Lot 17.

Overseeing laboratory testing of recovered soil samples.

Preparing a geotechnical report with recommendations for:

o Site development.

o Water treatment plant foundation design.


2. Site and Project Description

The project site is Lot 17 along the south side of Sawmill Creek Road near the north end of Silver Bay,

approximately 5 miles south and west of Sitka, Alaska. Lot 17 is bounded by Sawmill Creek Road to the

north, the UV facility to the west, an unnamed road to the east, and Lot 16 to the south. Appendix A Figure

1 shows the general project location.

Lot 17 measures approximately 105 by 165 feet and is a flat, open parcel of land that currently has debris

scattered over the surface and the remnants of old fill stockpile. The debris varied from trees, plastics,

metal cans and wires, to concrete rings. There is also an abandoned water line that served a hydrant on

the north side of Sawmill Creek Road. Reportedly, the water line was damaged under the load of the old

stockpile.

We understand the City of Sitka is considering development the lot for a new water treatment plant (WTP)

for a secondary water source. The proposed development includes site preparation, fill placement to raise

the current grade, establishment of a parking area, and construction of the WTP.


3. Subsurface Exploration

3.1 Subsurface Drilling

A geotechnical investigation was performed on May 30 and 31, 2018 to assess the soil conditions at the site. The investigation drilled and sampled three boreholes (BH-01 thru BH-03) and three drive penetrometer (P-1 thru P-3) tests. Field operations were supervised by a CRW geotechnical engineer, who logged the recovered soils and directed the drilling operation. The approximate borehole locations are shown on Figure 2 in Appendix A and borehole logs are presented in Appendix B. Select photos from the site investigation are in Appendix C.

The borehole locations were selected based on the site layout presented in CRW’s final Filtration Evaluation For Critical Secondary Water Source report (CRW, 2018) and then adjusted in the field based on site conditions and drill rig accessibility.

Drilling services were provided by Discovery Drilling, Inc. of Anchorage, Alaska, using a truck mounted CME-75 drill rig. The drill rig was equipped with a 3.25-inch inner diameter (I.D.) hollow stem auger, which was used to advance the borings and reach the target depths.

Three drive penetrometer tests were completed approximately 2 feet away from their closest boring. The penetrometer test is performed by advancing the NWJ drill rods using the split-spoon drop hammer with blows counted per foot as the drill rod advances. The results from the drive penetrometer testing is a continuous profile of general soil resistance and can provide some correlation to the Standard Penetration Test (SPT) to evaluate whether SPT blow counts are artificially lowered due to heave or higher due to obstructions. Penetrometer tests P-1 and P-3 were advanced to 54 feet below ground surface (bgs) and P-2 was advanced to 74 feet bgs.

3.2 Sample Collection

Soil characteristics, such as classification, consistency, moisture, and color were noted for each sample recovered. Classification was performed following the Unified Soils Classification System (USCS) according to ASTM D2487/D2488.

Soil samples were obtained by advancing an oversized split-spoon sampler into the soil beyond the bottom of the auger. Split-spoon samples were collected using a 3-inch outer diameter (O.D.) split-spoon sampler as a modified Standard Penetration Test (SPT). The sampler was driven 18 inches, counted in 6-inch intervals, using a 340-pound auto hammer. The number of blows required to drive the sampler each 6-inch interval is reported on the borehole logs. The blow counts shown on the borehole logs are field values that have not been corrected for overburden, sampler size, hammer energy, rod length, or other factors.

Heaving soils were encountered at times during the field exploration as noted on the borehole logs. Heaving conditions occur when saturated soil experiences a temporary and localized reduction in shear strength when disturbed by drilling action. Under certain conditions, soil can flow upward under hydrostatic pressure into the annulus of the hollow stem auger. Soil flowing inside the auger annulus may significantly influence blow counts and recovery of representative in-situ soil.

Split-spoon samples were collected at approximately 2.5-foot intervals for the first 10 feet and then 5-foot intervals thereafter to a depth of 50 feet bgs. Recovered samples were visually classified in the field before being individually sealed in double plastic bags and transported to Anchorage for additional testing. Field visual classifications were verified by laboratory testing.


3.3 Soil Lithology

The subsurface condition generally consisted a well graded gravel with sand and silt overlaying sand. The gravel was moist to wet when below the water table and was brown to brown/gray in color. The maximum particle size was 2 inches with gravel sizes ranging from coarse to fine and subangular in shape. The gravel content varied from 47 to 62 percent. The sand content varied from 31 to 44 percent and the fines content varied from 7 to 11 percent. The gravel layer extended to a depth of approximately 20 to 25 feet bgs.

Underlying the gravel was a sand deposit that varied from a silty sand with gravel to a well graded sand with gravel and silt. The sand layer was wet below the water table, brown to brown/gray in color, and ranged from coarse to fine in size. The gravel content varied from 15 to 40 percent. The sand content varied from 44 to 78 percent. The fines content varied from 8 to 20 percent with a general decrease in fines content with depth.

Between the gravel and sand deposit was a thin layer of moist, brown, sandy silt to silty sand. The layer varied in thickness from 2 to 3.5 feet thick and ranged from 6 to 10 feet bgs. The sandy silt was non-plastic to slightly plastic. Pocket penetrometer measurements indicated the silt to have an unconfined compression strength of 1,000 pounds per square foot (psf) designating its consistency as soft. Organic matter was noted in the sandy silt.

Bedrock was not encountered in any of borings. The depth to bedrock is unknown though past work in the project area has shown bedrock to be between 78 to 141 feet bgs (S&W, 2014).

3.4 Groundwater Levels and Borehole Completion

Groundwater levels were noted during drilling through the observation of color changes on the drill rod and the visual water content of recovered samples. No piezometers were installed as part of the investigation. A summary of the groundwater depths is presented in Table 2.

All boreholes were backfilled with auger cuttings brought to the ground surface during drilling. Excess auger cuttings were spread around the borehole area.


4. Laboratory Testing and Results

Soil laboratory tests to evaluate index properties of representative samples were performed by Alaska

Testlab (ATL) in their Anchorage, Alaska facility. The laboratory testing program consisted of soil index

tests to determine the water content, grain-size distribution, and Atterberg Limits.

The laboratory tests were performed in accordance with the test methods of ASTM International. In

total, 40 samples were submitted for testing. Water content for all samples was tested in accordance

with ASTM D2216. The water content varied between 5 to 78 percent with higher water contents

observed in samples with organic content.

Seven samples were selected for grain-size distribution testing in accordance with ASTM D422. Five of

the samples were well graded sand and gravel and were classified as GW-GM/SW-SM per USCS. Two of

the samples were silty sand, SM, per USCS.

Six samples were washed through the No. 200 mesh sieve in accordance with ASTM D1140. The coarse

fraction of the remaining soil was then dried and sieved through the No. 4 sieve to determine the

percentage of sand and gravel. This method is termed the Limited Mechanical Analysis (LMA). The LMA

is a means to determine the percentage of coarse and fine soil in a sample without having to perform

full gradations.

One sample from the near surface sandy silt was tested for its Atterberg Limit per ASTM D4318. This

sample was non-plastic.

Results of the laboratory testing are presented in Appendix D.


5. Site Conditions

5.1 Seismic Considerations

The project site lies in a region of moderate to high seismicity, and is subject to relatively large earthquakes and strong ground motion. The Alaska Earthquake Center (AEC) has recorded several moment magnitude earthquakes larger than 7.0, including earthquakes in 2012 and 2013 which were 7.8 and 7.5 magnitude, respectively.

Seismic design parameters were determined using the U.S. Seismic Design Maps online tool from the United States Geological Survey (https://earthquake.usgs.gov/hazards/designmaps/). Table 1 provides the seismic design parameters for the 2,475-year (2 percent in 50 years) return period, Design Response spectrum, consistent with the International Building Code (IBC). Based on the SPT blow counts, Site Class D was assigned to the site, per the IBC.

Table 1 – Seismic Design Parameters

Description Value

Moment Magnitude, Mw 7.7

Return Period 2,475-year

Peak Ground Acceleration 0.264g

SDS (0.2 second period acceleration) 0.661g

SD1 (1 second period acceleration) 0.594g

5.2 Groundwater Conditions

Groundwater was observed in all boreholes advanced for this project and appeared to be tidally influenced. Table 2 provides a summary of the depths of groundwater observed during drilling. Time at which samples were taken can be found on the borehole logs and confirm the fluctuations in groundwater depths to be influenced by the tide elevation at the time of day the boring occurred.

Table 2 – Summary of Groundwater Levels

Borehole Depth of Groundwater during drilling (feet bgs)

BH-01 16.0

BH-02 21.0

BH-03 14.0

5.3 Frost Depth and Permafrost

Seasonal frost was not observed in any of the borings. Per CBS’s structural design criteria, the minimum footing depth for frost is 18 inches.

We estimated a design frost depth based on the modified Berggren equation using the commercially available Microsoft DOS program Berg2. Our analysis considers the climate data for Sitka found in Table

https://earthquake.usgs.gov/hazards/designmaps/


3. We calculated the freezing and thawing indices based on published air temperature data for the past 30 years downloaded from the National Oceanic and Atmospheric Administration (NOAA, www.ncdc.noaa.gov/cdo-web/datasets). We have estimated n-factors for depth of freeze and depth of thaw based on published values (Andersland and Ladayni, 2004) and our experience.

Table 3 – Climatic Berg2 Inputs for Sitka

Description Value

Thaw n-factor 1.7

Freeze n-factor 1.0

Design Air Thawing Index (°F-days) 5,775

Design Air Freezing Index (°F-days) 223

Mean Annual Air Temperature (°F) 45.4

Amplitude of Air Temperature Sine Wave (°F) 16.0

We assumed a soil profile as shown in Figure 1. Based on these inputs, we estimate a design frost depth of 1.75 feet.

Figure 1 – Berg2 Analysis output

Permafrost was not encountered in the boreholes and is not expected at the project site.

http://www.ncdc.noaa.gov/cdo-web/datasets


6. Geotechnical Engineering Recommendations

6.1 Generalized Soil Profile

CRW has developed a generalized soil profile for Lot 17 based on the in-situ and laboratory testing. A summary of the soil properties is shown in Table 4. The properties are based on the results of index testing from the laboratory, results from the pocket penetrometer testing, and published correlations SPT blow counts (Bowles, 1997; EPRI, 1990). It should be noted that the depths shown in the table reference the grade of the site at the time of the geotechnical investigation.

Table 4 – Generalized Soil Profile

Depth (feet)

Soil Type

(N1)60 (bpf)

Total Unit

Weight (pcf)

Friction Angle,

’, (°)

Cohesion (psf)

Undrained Shear

Strength (psf)

0 – 6 Well graded GRAVEL with silt 25 130 37 0 -

6 – 10 Sandy SILT 15 115 28 0 500

10 – 25 Well graded GRAVEL with silt 45 130 40 0 -

25 – 35 Silty SAND 30 125 32 0 -

35 - 51.5 Well graded SAND with silt 20 120 30 0 -

A plot of the drive penetrometer test results are shown in Figure 2. The plots shows the sandy silt layer being a weaker layer relative to the gravel layers above and below it. The penetrometer also showed a decrease in density of the granular soils from approximately 20 feet bgs to around 50 feet bgs where the density appears to then increase. A table of values from the drive penetrometer testing is found in Appendix E.


Figure 2 – Lot 17 Drive Penetrometer Test Results

6.2 Stability Evaluation

6.2.1 Slope Instability

The site is relatively flat, therefore, by inspection, slope instability is deemed of no concern.

6.2.2 Loss of Bearing Capacity

Assuming any foundations do not bear on deleterious material, an inspection of blow counts and soil type suggest that the risk of loss of bearing capacity in the top 25 feet of the soil during a seismic event is low.

6.2.3 Liquefaction and Surface Manifestations

Liquefaction is the result of the buildup of excess pore water pressure, beyond hydrostatic, generated in an undrained soil loading condition. In this condition, partial or complete loss of inter-particle friction within the soil mass occurs, resulting in dramatic decrease of the soil’s shear strength. This excess pore water pressure is typically generated in fine, loose sands though other soil conditions, and densities can experience lesser magnitudes of liquefaction resulting in some degree soil strength loss.

0

10

20

30

40

50

60

70

80

0 15 30 45 60 75 90 105 120 135 150 165

Dep

th, f

eet

Penetrometer, blows/ft

P-1

P-2

P-3


The most common methodology for assessing the potential of liquefaction for uniform, medium- to fine-grained, saturated sand is based on an empirical database using SPT blow counts. The empiricism is based on sites where liquefaction had and had not occurred. The assessment for liquefaction potential further considers the degree of saturation, the fines content, earthquake magnitude, age and origin of the soil deposit, mineralogy, and depth bgs.

The approach to assessing for liquefaction potential based on SPT data is accomplished by first correcting the field blow counts to their (N1)60 values and proceeding to evaluate the soil’s strength, designated as Cyclic Resistance Ratio (CRR). The load on the soil is then computed as the Cyclic Stress Ratio (CSR). The ratio of CRR divided by CSR defines the Factor of Safety against liquefaction, FSLIQ.

We performed a liquefaction assessment following the simplified procedure of Youd et al (2001). We determined that there is a liquefaction potential in the sand deposit. This result is consistent with past work by others in the area (S&W, 2014). The thickness of the zone of liquefaction potential varied by boring. Figure 3 shows the Factor of Safety against liquefaction vs. depth for Lot 17 based on our analysis. Note that no modifications to the site from fill or other construction activities are accounted for in this analysis and only saturated samples are considered.

Figure 3 – Lot 17 Factor of Safety against Liquefaction vs. Depth

0

10

20

30

40

50

60

0 0.5 1 1.5 2

Dep

th, f

eet

Factor of Safety Against Liquefaction

BH-01

BH-02

BH-03


The results of our analysis show that potential for liquefaction exists between approximately 25 to 55 feet bgs though, as noted, the thickness varies by boring. For example, BH-01 was determined to have liquefaction potential from 40 to between 45 to 50 feet bgs. The results from the penetrometer testing suggests that below 55 feet there is little to no risk of liquefaction. This conclusion is based on an inspection of the (N1)60 vs. penetrometer blows per foot.

Results of liquefaction include surface manifestations from the reorganization of soil particles resulting in settlement, sand boils, lateral spreading of sloping ground, and surface cracking.

Post-liquefaction settlement is deemed to be the primary surface manifestation. It is our opinion that differential settlement will be of greatest concern to structure performance. We computed post-liquefaction settlements using procedures for sands by Idriss and Boulanger (2008) and Tokimatsu and Seed (1987) and evaluated the differential settlement considering total settlement values at each boring. Estimated differential settlement was approximately 4 inches over 50 feet.

The assessment of surface manifestations for sand boiling followed Kramer (1996) and determined that the top 25 feet of gravel provided adequate thickness to mitigate the potential for sand boils.

Liquefaction-induced lateral deformations are termed lateral spreading. We evaluated lateral spreading, considering the method outlined by Youd et al. (2002). The procedure considers the earthquake magnitude, distance to the seismic source, thickness of the liquefiable layer, fines content, average particle size, and slope of the terrain. The results of the lateral spread analysis determined the deformations to be approximately 1 inch considering a 0.3 percent sloped ground and 2.2 inches considering a 2 percent sloped ground.

6.3 Liquefaction Mitigation

There are two techniques to address the liquefaction potential in terms of performance of the WTP. These techniques are either ground improvement to eliminate the liquefaction potential or designing the foundation to accommodate the differential settlement. It should be noted that some densification and confinement will result during fill placement, which should be accounted for during design.

A number of ground improvement options are available to mitigate the liquefaction potential including, but not limited to: vibro-compaction, dynamic compaction, stone columns, earthquake drains, grouting, and deep soil mixing. A screening of the site surface and subsurface conditions was performed to evaluate a ground improvement option using the Strategic Highway Research Program (SHRP2) at www.geotechtools.org. The screening determined several options and based on our experience of costs we further reduced the options to either stone columns or sand compaction piles as the most feasible and cost effective potential solutions.

The second technique would be to design the foundation system to accommodate the differential settlement predicted from the liquefaction analysis. We believe two approaches are available to the designers. The first approach would be a mat foundation designed to accommodate the differential movement. The second approach would be conventional spread footings over a geosynethic-reinforced embankment (GRE) (Han, 2015). The GRE will require a detailed analysis to evaluate the differential settlement considering geosynethic layout and stiffness vs. strain in an embankment.

CRW recommends the proposed WTP be designed to accommodate the differential settlement in-lieu of ground improvement options.

http://www.geotechtools.org/


6.4 Foundation Recommendations

Shallow and deep foundations are used to transfer building loads to the underlying soil. The soil type, consistency/density, compressibility, heave/swell/collapse potential, groundwater table, and depth to and type of bedrock are all considered in the type of foundation recommended for the proposed infrastructure.

The soils encountered at the project site are conducive to shallow foundations, including spread footings, continuous footings, and mat foundations. We recommended the use of spread/continuous footings or mat foundation to carry the expected building loads.

6.4.1 Bearing Capacity and Settlement

The design of shallow foundations must consider the bearing capacity of the underlying soil, as well as the potential for settlement and the effects of seasonal frost action. In general, foundation designs should be consistent with the current editions of the International Building Code (IBC) and any local amendments or requirements.

Perimeter continuous footings, interior spread footings, and mat foundations should bear on a minimum of 12 inches of compacted, engineered fill prepared in accordance with our recommendations. If our fill and compaction recommendations are followed, the foundation may be designed according to the following criteria.

Maximum Allowable Bearing Pressure (includes a factor of safety of 3)

o Static Loads (Dead and Normal Live): 3,000 psf

o Transient Loads (Wind and Seismic): Increase static by 33 percent

Applies to continuous and square, or nearly square, footings that are not eccentrically-loaded with a minimum width of 1.5 feet and a maximum width of 8.0 feet and considers the sandy silt being at least 12 feet below the bottom of footing. If footings are closer than the assumed 12 feet, the bearing capacity and settlement should be evaluated by the designers. The effective bearing area of eccentrically-loaded footings will be less than the actual footing dimensions, and may vary depending on anticipated design loads and eccentricity. These values do not apply to footings on a slope. Bearing capacity for larger footings can be provided on request.

Depth of Embedment (from finish grade to base of footing)

o Perimeter Footings: 24 inches, minimum

o Interior Footings: 12 inches, minimum

Interior footing is assumed to be warm footing. The depth should be measured from adjacent grade to bottom of footing.

Settlement (Static - Elastic)

o Total Settlement 1.0 inch

o Differential Settlement (excluding post-liquefaction) 0.5 inch

6.4.2 Lateral Load Resistance

Lateral loads on footings will be resisted by passive earth pressures developed against the side of the footing and frictional resistance against the base of the footing. We recommend a passive resistance


(equivalent fluid pressure) of 260 pcf (psf/foot). This equivalent fluid pressure includes a factor of safety of 2.0. A friction coefficient of 0.50 is recommended for resistance to lateral sliding, assuming the footing is concrete and cast directly against sand and gravel. The passive resistance should not exceed 2,000 psf. Friction and passive earth pressure resistance may be combined without reduction.

6.4.3 Uplift Resistance

Uplift loads may occur in some foundation elements due to overturning moments resulting from wind and seismic forces. Uplift loads may be resisted by the weight of the footing and soil within the limits of a truncated pyramid above the top of the footing. The shape of the truncated pyramid will vary with material type and density. For typical fill soils anticipated for the project, the pyramid should be defined by a 20 degree angle from a vertical line extending upward from the top of the footing.

6.4.4 Mat Foundation Recommendations

For any mat foundations, we recommend the use of a subgrade reaction modulus to design the slab. The modulus of subgrade reaction is not an intrinsic property of the soil, but also depends on the dimension and the stiffness of the slab. Assuming our recommendations are followed, a coefficient of subgrade reaction, K1, for a 1-foot diameter plate of 150 pounds per cubic inch (pci) can be used for design. This subgrade reaction can then be used to adjust to a subgrade reaction for the mat foundation per the designer’s procedure.

We recommend the mat foundation be designed to tolerate a 1 foot cantilever and 2 foot internal span. The post-liquefaction differential settlement should also be accounted for in design.

6.5 Retaining Walls and Lateral Earth Pressures

Retaining walls, including those used for basements or crawl spaces, must be designed to resist lateral earth pressures plus lateral pressure due to surcharge loads applied at the ground surface behind the wall. The magnitude of the earth pressure varies depending on permissible wall movement, type of backfill, compaction, and drainage.

We recommend the use of clean, free-draining, and properly-compacted (per our construction recommendations) coarse-grained soil for backfill, with drainage provisions to prevent the buildup of hydrostatic pressure on the wall. All retaining wall recommendations are based on the assumption that these conditions exist. Alternate recommendations can be provided, should differing materials or drainage exist. Additional lateral loads due to surface loads are not included in the equivalent fluid densities below.

The active earth pressure condition for static loading should be designed to resist the lateral earth pressure exerted by a fluid with a density of 37 pcf (psf/foot) if the retaining wall is allowed to deflect or rotate a minimum of 0.001 times the wall height.

The at-rest pressure condition will occur if the wall is restrained at the top and cannot move sufficient to permit the active earth pressure condition to exist. Under this condition, retaining walls should be designed to resist the lateral earth pressure exerted by a fluid with a density of 55 pcf (psf/foot).

The passive earth pressure condition for static loading should be designed following the values discussed in Section 6.4.2.

We recommended any foundation stem walls be backfilled on both sides simultaneously to prevent differential lateral loading of the foundation wall.


6.6 Slope Stability

The fill placement to raise the project grade will likely result in some soil slopes as part of the site development. For new embankments, we recommend side slopes be no steeper than 2H:1V (horizontal to vertical) assuming the slopes are constructed from engineered fill and compacted following our construction recommendations. Slopes constructed of poorer quality fill material will need to be flatter. A more detailed stability analysis should be performed if poorer quality fill material is used or steeper slopes are required.

Engineered slopes at the recommended 2H:1V will perform well though some minor sloughing and rills will likely occur over time due to runoff/infiltration under static conditions. During strong ground motions, some displacements are expected with the primary effect anticipated to be rotational failures of the slope edges. More detailed seismic slope stability analyses can be performed on request.

6.7 Utility Recommendations

All excavations for utilities should follow proper local, state, and federal requirements, including OSHA. The contractor is responsible for trench stability, worker safety, and regulation compliance. The water table was encountered at approximately 14 to 21 feet bgs. Therefore, dewatering is not anticipated to be required. However, surface runoff entering the excavation could present challenges and should be accounted for during construction.

All utilities should be bedded per the manufacturer’s recommendations, with the bedding material compacted to provide support. Backfill around and over the utilities should be similar to the in-situ gravels and compacted.

6.8 Pavement Recommendations

The project site is expected to be paved. At a minimum, we recommend the pavement structural section consist of (in descending order) 2 inches of asphalt, 6 inches of a leveling course consistent with State of Alaska D-1 material, and 24 inches of engineered fill consistent with the State of Alaska Type A select material.


7. Construction Recommendations

7.1 Site Preparation

All earthworks should be performed in accordance with the project specifications and with local, state, and federal laws and regulations.

All trees and small brush should be removed prior to starting any earthwork. We recommend the removal of all debris and deleterious material on the surface be removed prior to fill placement. We further recommend removal of the abandoned water line prior to fill placement and site development. The sandy silt layer is not required to be removed provided adequate bearing capacity and settlement performance is achieved during design. The sandy silt layer should be removed if, during design, poor foundation performance is predicted.

7.2 Fill Placement and Compaction

7.2.1 Engineered Fill Placement and Compaction General Requirements

All fill material should be thawed, free from lumps, organics, debris, and other deleterious material and should be durable and sound.

A vibratory steel drum roller should be used to compact engineered fill. However, lightweight or hand-operated compactors should be used near existing structures, utilities, or new footings to avoid damage to the footings.

No hauling or grading equipment should be used in lieu of appropriate compaction equipment. Any loosening of fill material by hauling or other equipment should be repaired and re-compacted. The number of passes required to meet the compaction requirement will depend on the size of compaction equipment used. Each layer should be compacted as recommended in this report and field verification of compaction requirements is recommended.

Foundation soils should be protected from freezing during construction. No frozen soil should be used as fill, nor should any fill be placed over frozen soil. Any frozen soil should be removed and replaced with thawed fill prior to construction.

7.2.2 Engineered Fill and Compaction

We recommend the engineered fill be clean, well-graded sand and gravel and be non-frost susceptible (NFS). The gradation of the engineered fill should be consistent with the State of Alaska Department of Transportation Standard Specification for Select Material Type A.

Engineered fill should be placed in loose lifts not exceeding 12 inches in thickness if a large vibratory compacted is used, or not exceeding 4 inches in thickness if a lightweight or hand operated compactors are used. Each lift of engineered fill should be compacted to at least 95 percent of its Modified Proctor Maximum Density determined per ASTM D1557.

7.3 Excavation Slopes

Temporary excavations into soil should be performed in accordance with OSHA or other agency guidelines and recommendations for trenching and slope angles based on soil type encountered. Permanent excavations into soil should either be retained or sloped to meet long-term stability requirements. The ground around open excavations should be contoured to direct surface water away from the excavations.


Excavation and backfilling operations should be closely coordinated so that seepage and surface runoff is not allowed to collect and stand in open trenches for long periods.

All debris should be removed from areas beneath the buildings and parking areas and replaced with material as recommended in this report and following all project specifications.

Excavations should be performed by a backhoe with a smooth-bladed bucket from outside the excavation to minimize disturbance of the subgrade soils. Soils that are disturbed, pumped, or rutted by construction activity should be re-compacted or removed prior to placement of any structural, classified, or unclassified fill.

We recommend foundation excavations extend laterally 5 feet beyond the perimeter of the proposed foundation in every direction and be backfilled and compacted with engineered fill following the recommendations of this report.

7.4 Drainage and Control of Water

Excavations may experience seepage due to shallow, perched water or surface runoff, and should be monitored during construction. Parking areas should have positive gradients toward drainage structures and away from buildings. Site grading should be established to provide drainage of surface water and roof drainage away from proposed buildings.

The ground immediately adjacent to the building foundation should be sloped away at a minimum of 5 percent for a minimum distance of 10 feet, measured perpendicular to the face of the wall. Grading should be designed to prevent ponding of surface water except where retention ponds or similar devices are intended.


8. Limitations and Closure

The information submitted in this report is based on our interpretation of data from a field geotechnical exploration performed for this project in May 2018. Effort was made to obtain information representative of existing conditions at the site. If, however, subsurface conditions are found to differ, we should be notified immediately to review these recommendations in light of additional information.

This report was prepared by CRW Engineering Group, LLC for use on this project only, and may not be used in any manner that would constitute a detriment to CRW. CRW is not responsible for conclusions, opinions, or recommendations made by others based on data presented in this report.


9. References

Alaska Earthquake Center, AEC. Found online at http://earthquake.alaska.edu/ [accessed June 2018]

Andersland, O.B., and Ladanyi, B., 2004. Frozen Ground Engineering, 2nd edition. American Society of Civil Engineers and John Wiley & Sons, Inc.

Bowles, E.J., 1997. Foundation Analysis and Design, 5th edition. McGraw-Hill Companies, Inc., Illinois.

CRW Engineering Group, LLC, 2018. Filtration Evaluation for Critical Secondary Water Source Final Report. A report prepared for the City and Borough of Sitka, April 2018.

EPRI, 1990. Manual on Estimating Soil Properties for Foundation Design. EPRI EL-6800 Project 1493-6 Final Report, New York.

Han, J., 2015. Principles and Practice of Ground Improvement. John Wiley & Sons, Inc. Hoboken, New Jersey.

Idriss, I.M. and Boulanger, R.W., 2008. Soil Liquefaction During Earthquakes. Earthquake Engineering Research Institute, MNO-12.

Kramer, S.L., 1996. Geotechnical Earthquake Engineering. Prentice Hall, Upper Saddle River, N.J.

Seed, R.B., Cetin, K.L., Moss, R.E.S., Kammerer, A.M., Wu, J., Pestana, J.M., Riemer, M.F., Sancio, R.B., Bray, J.D., Kayen, R.E., and Faris, A., 2003. Recent Advances in Soil Liquefaction Engineering: A Unified and Consistent Framework. Keynote Presentation, 26th Annual ASCE Los Angles Geotechnical Spring Seminary, H.M.S. Queen Mary, Long Beach, California, April 30, 2003.

Shannon and Wilson (S&W), 2014. Geotechnical Data Report Gary Paxton Industrial Park Multi-Use Dock Sawmill Cove, Sitka, Alaska. A report submitted to Moffatt & Nichol, September 2014.

Tokimatsu, K., and Seed, H.B., 1987. Evaluation of Settlements in Sand Due to Earthquake Shaking. Journal of Geotechnical Engineering, Vol. 113, No.8, pp. 861-878.

Youd, T.L., Idriss, I., Andrus, R., Arango, I., Castro, G., Christian, J., Dobry, R., Liam Finn, W., Harder, L., Hynes, M., Ishihara, K., Koester, J., Liao, S., Marcuss, W., Martin, G., Mithcell, J., Moriwaki, Y., Power, M., Robertson, P., Seed, R., and Stokoe, K., 2001. Liquefaction Resistance of Soils: Summary Report From the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils. Journal of Geotechnical and Geoenvironmental Engineering, ASCE 127(10), 817-833.

Youd, T.L., Hansen, C.B., and Bartlett, S.F., 2002. “Revised Multilinear Regression Equations for Predictions of Lateral Spread Displacement,” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 128, Issue 12, pp. 1007-10174, December 2002.

http://earthquake.alaska.edu/

APPENDIX A

Figures

SITKA

ANCHORAGE

NOME

KOTZEBUE

BARROW

JUNEAU

FAIRBANKS

KODIAK

BETHEL

UNALASKA

APPENDIX B

Borehole Logs

SOIL CLASSIFICATION / LEGEND

N.T.S.

4/25/2018

A-1

RELATIVE DENSITY / CONSISTENCY ESTIMATE USING

STANDARD PENETRATION TEST (SPT) VALUES

(FROM TERZAGHI & PECK 1996)

COHESIONLESS SOILS

(a)

COHESIVE SOILS

(b)

RELATIVE

DENSITY

N

60

(BLOWS/FOOT)

(c)CONSISTENCY

N

60

(BLOWS/FOOT)

(c)

UNCONFINED

COMPRESSIVE

STRENGTH (TSF)

(d)

VERY LOOSE 0 - 4 VERY SOFT 0 - 2 0 - 0.25

LOOSE 4 - 10 SOFT 2 - 4 0.25 - 0.50

MED DENSE 10 - 30 MEDIUM 4 - 8 0.50 - 1.0

DENSE 30 - 50 STIFF 8 - 15 1.0 - 2.0

VERY DENSE OVER 50 VERY STIFF 15 - 30 2.0 - 4.0

HARD OVER 30 OVER 4.0

(a) Soils consisting of gravel, sand and silt, either separately or in combination possessing no characteristics of plasticity, and exhibiting

drained behavior.

(b) Soils possessing the characteristics of plasticity, and exhibiting undrained behavior.

(c) Refer to ASTM D 1586-99 for a definition of N.

(d) Undrained shear strength, s

u

= 1/2 unconfined compression strength, U

c

. Note that Torvane measures s

u

and Pocket Penetrometer

measures U

c

.

Gravels or sands with 5% to 12 % fines require dual symbols (GW-GM, GW-GC, GP-GM, GP-GC,

SW-SM, SW-SC, SP-SM, SP-SC) and add "with clay or "with silt" to group name. If fines classify as

CL-ML for GM or SM, use dual symbol GC-GM or SC-SM.

Optional Abbreviations: Lower case "s" after USCS group symbol denotes either "sandy or "with sand"

and "g" denotes either "gravelly" or "with gravel."

CRITERIA FOR DESCRIBING MOISTURE

CONDITION (ASTM D 2488)

DRY

ABSENCE OF MOISTURE, DUSTY,

DRY TO THE TOUCH

MOIST DAMP BUT NO VISIBLE WATER

WET

VISIBLE FREE WATER, USUALLY

SOIL IS BELOW WATER TABLE

COMPONENT DEFINITIONS BY GRADATION

COMPONENT SIZE RANGE

BOULDERS ABOVE 12 IN.

COBBLES 3 IN. TO 12 IN.

GRAVEL

3 IN. TO NO. 4 (4.76 mm)

COARSE GRAVEL 3 IN. TO 3/4 IN.

FINE GRAVEL

3/4 IN. TO NO. 4 (4.76 mm)

SAND

NO. 4 (4.76 mm) TO NO. 200 (0.074 mm)

COARSE SAND

NO. 4 (4.76 mm) TO NO. 10 (2.0 mm)

MEDIUM SAND

NO 10 (2.0 mm) TO NO. 40 (0.42 mm)

FINE SAND

NO. 40 (0.42 mm) TO NO. 200 (0.074 mm)

SILT AND CLAY

SMALLER THAN NO. 200 (0.074 mm)

SILT 0.074 mm TO 0.005 mm

CLAY LESS THAN 0.005 mm

DESCRIPTIVE TERMINOLOGY FOR

PERCENTAGES (ASTM D 2488)

DESCRIPTIVE

TERMS

RANGE OF

PROPORTION

TRACE 0 - 5%

FEW 5 - 10%

LITTLE 10 - 25%

SOME 30 - 45%

MOSTLY 50 - 100%

SAMPLER ABBREVIATIONS

SS

SPT Sampler (2 in. OD, 140 lb hammer)

C

Core (Rock)

SSO

Oversize Spit Spoon (2.5 in. OD, 140 lb typ.)

TW

Thin Wall (Shelby Tube)

HD

Heavy Duty Split Spoon (3 in. OD, 300/340 lb typ.)

MS

Modified Shelby

BD

Bulk Drive (4 in. OD, 300/340 lb hammer typ.)

GP

Geoprobe

CA

Continuous Core (Soil in Hollow-Stem Auger)

AR

Air Rotary Cuttings

G

Grab Sample from surface / testpit

AG

Auger Cuttings

LABORATORY TEST ABBREVIATIONS

Consol Consolidation PM Modified Proctor TXCD Consolidated Drained Triaxial

Dd

Dry Density

PP Pocket Penetrometer TXCU Consolidated Undrained Triaxial

MA

Sieve and Hydrometer Analysis

MC Moisture Content TXUU Unconsolidated Undrained Triaxial

NP

Non-plastic

SA

Sieve Analysis

LL

Liquid Limit

OLI

Organic Loss SpG Specific Gravity

PL Plastic Limit

P200

Percent Fines (Silt & Clay)

TS Thaw Consolidation VS Vane Shear

PID Photoionization Detector TV Torvane Ω Soil Resistivity

UNIFIED SOIL CLASSIFICATION (ASTM D 2487)

FIGURE

B-1

FROZEN SOIL CLASSIFICATION / LEGEND

N.T.S.

4/25/2018

A-2

FROZEN SOIL CLASSIFICATION (ASTM D 4083)

1. DESCRIBE SOIL

INDEPENDENT OF

FROZEN STATE

CLASSIFY SOIL BY THE UNIFIED SOIL

CLASSIFICATION SYSTEM

MAJOR GROUP SUBGROUP

DESCRIPTION DESIGNATION DESCRIPTION DESIGNATION

Segregated

ice not visible

by eye

N

Poorly bonded of friable

N

f

Well

bonded

No excess ice Nbn

Excess ice Nbe

2. MODIFY SOIL

DESCRIPTION BY

DESCRIPTION OF

FROZEN SOIL

Segregated ice

visible by eye

(ice less than

25 mm thick)

V

Individual ice crystals or

inclusions

V

x

Ice coatings on particles

V

c

Random or irregularly

oriented ice formations

V

r

Stratified or distinctly

oriented ice formations

V

s

Uniformly distributed ice

V

u

Ice greater than

25 mm thick ICE

Ice with soil inclusions

ICE+soil type

3. MODIFY SOIL

DESCRIPTION BY

DESCRIPTION OF

SUBSTANTIAL ICE

STRATA

Ice without soil inclusions ICE

ICE BONDING SYMBOLS

No ice-bonded soil

observed

Poorly bonded or

friable

Well bonded

Candled Ice is ice which has rotted or otherwise

formed into long columnar crystals, very loosely

bonded together.

Clear Ice is transparent and contains only a

moderate number of air bubbles.

Cloudy Ice is translucent, but essentially sound

and non-pervious.

Friable denotes a condition in which material is

easily broken up under light to moderate pressure.

Granular Ice is composed of coarse, more or less

equidimensional, ice crystals weakly bonded

together.

Ice Coatings on particles are discernible layers of

ice found on or below the larger soil particles in a

frozen soil mass. They are sometimes associated

with hoarfrost crystals, which have grown into

voids produced by the freezing action.

Ice Crystal is a very small individual ice particle

visible in the face of a soil mass. Crystals may be

present alone or in a combination with other ice

formations.

Ice Lenses are lenticular ice formations in soil

occurring essentially parallel to each other,

generally normal to the direction of heat loss and

commonly in repeated layers.

Ice Segregation is the growth of ice as distinct

lenses, layers, veins and masses in soils,

commonly but not always oriented normal to

direction of heat loss.

Massive Ice is a large mass of ice, typically nearly

pure and relatively homogeneous.

Poorly-Bonded signifies that the soil particles are

weakly held together by the ice and that the frozen

soil consequently has poor resistance to chipping

or breaking.

Porous Ice contains numerous void, usually

interconnected and usually resulting from melting

at air bubbles or along crystal interfaces from

presence of salt or other materials in the water, or

from the freezing of saturated snow. Though

porous, the mass retains its structural unity.

Thaw-Stable frozen soils do not, on thawing, show

loss of strength below normal, long-time thawed

values nor produce detrimental settlement.

Thaw-Unstable frozen soils show on thawing,

significant loss of strength below normal, long-time

thawed values and/or significant settlement, as a

direct result of the melting of the excess ice in the

soil.

Well-Bonded signifies that the soil particles are

strongly held together by the ice and that the

frozen soil possesses relatively high resistance to

chipping or breaking.

FROST DESIGN SOIL CLASSIFICATION

(1)

FROST GROUP

(2)

GENERAL SOIL TYPE

% FINER THAN

0.02 mm BY

WEIGHT

TYPICAL USCS

SOIL CLASS

NFS

(3)

(a) Gravels

Crushed stone

Crushed rock

0 - 1.5GW, GP

(b) Sands

0 - 3SW, SP

PFS

(4)

[MOA NFS]

(a) Gravels

Crushed stone

Crushed rock

1.5 - 3GW, GP

[MOA F2] (b) Sands

3 - 10SW, SP

S1

[MOA F1]

Gravelly soils

3 - 6

GW, GP, GW-GM, GP-GM,

GW-GC, GP-GC

S1

[MOA F2]

Sandy soils

3 - 6

SW, SP, SW-SM, SP-SM,

SW-SC, SP-SC

F1

(5)

Gravelly soils

6 - 10

GM, GC, GM-GC, GW-GM,

GP-GM, GW-GC, GP-GC

F2

(5)

(a) Gravelly soils

10 - 20

GW, GP, GW-GM, GP-GM,

GW-GC, GP-GC

(b) Sands

6 - 15

SM, SW-SM, SP-SM, SC,

SW-SC, SP-SC, SM-SC

F3

(5)

(a) Gravelly soils

10 -20GM, GC, GM-GC

(b) Sands, except very fine silty

sands

6 - 15SM, SC, SM-SC

(c) Clays, PI>12

--CL, CH

F4

(5)

(a) Silts

--ML, MH, ML-CL

(b) Very fine silty sands

Over 15SM, SC, SM-SC

(c) Clays, PI<12

--CL, ML-CL

(d) Varved clays or other fine-grained

banded sediments

--

CL or CH layered with ML, MH,

ML-CL, SM, SC, or SM-SC

(1) From the U.S. Army Corps of Engineers (USACE), EM 1110-3-138, "Pavement Criteria for Seasonal Frost Conditions", April 1984

(2) USACE frost groups directly correspond to frost groups in Municipality of Anchorage (MOA) Design Criteria Manual (DCM).

(3) Non-frost susceptible

(4) Possibly frost susceptible, requires lab test for void ratio to determine frost design classification.

DEFINITIONS

(5) Consistent with MOA Definition.

FIGURE

B-2

HD1

HD2AHD2B

HD3AHD3B

HD4

HD5

HD6

HD7

83

100

100

100

100

89

89

83

89

9-8-10(18)

12-9-4(13)

7-18-28(46)

19-17-19(36)

23-17-24(41)

9-13-16(29)

14-12-12(24)

Lots of grinding onaugers.

MC = 6%SA

Sample taken at8:45 AM.

MC = 10%Sample taken at

8:55 AM.MC = 38%

PP = 0.5 tsfMC = 13%

Sample taken at9:10 AM.MC = 6%

Pushing rock.MC = 9%

LMASample taken at

9:20 AM.Grinding on

augers.


9:30 AM.


9:42 AM.


9:53 AM.

GP-GM

ML

GP-GM

GP-GM

SM

6.0

8.0

16.0

25.0

POORLY GRADED GRAVEL WITH SILT AND SAND, (GP-GM) 58% gravel,34% sand, 8% fines, grayish brown, subangular, fine to coarse grained, moist,up to 2" particle size.

SANDY SILT, (ML) brown, moist, non plastic, root in tip.

POORLY GRADED GRAVEL WITH SILT AND SAND, (GP-GM) 48% gravel,42% sand, 9% fines, gray, subangular, fine to coarse grained, moist, up to 2"particle size.

POORLY GRADED GRAVEL WITH SILT AND SAND, (GP-GM) gray,subangular, fine to coarse grained, wet, up to 2" particle size.

SILTY SAND WITH GRAVEL, (SM) 38% gravel, 44% sand, 12% fines, brown,subangular, fine to coarse grained, wet, up to 1.5" particle size.

NOTES Surface: Shot rock fill

GROUND ELEVATION

LOGGED BY SMH

DRILLING METHOD Hollow-Stem Auger

HOLE SIZE 3.25 inches

DRILLING CONTRACTOR Discovery Drilling GROUND WATER LEVELS:

CHECKED BY SMH/MCH

DATE STARTED 5/30/18 COMPLETED 5/30/18

AT TIME OF DRILLING 16.00 ft

AT END OF DRILLING ---

AFTER DRILLING ---

(Continued Next Page)

DE

PT

H(f

t)

0

5

10

15

20

25

30

SA

MP

LE T

YP

EN

UM

BE

R

ICE

BO

ND

PAGE 1 OF 2BOREHOLE BH-01

PROJECT NAME Lot 17

PROJECT LOCATION Sitka, Alaska

CLIENT City and Borough of Sitka

PROJECT NUMBER 21201.02

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JCRW Engineering Group LLC3940 Arctic BlvdAnchorage, AK 99503Telephone: (907) 562-3252Fax: (907) 561-2273

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MATERIAL DESCRIPTION

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HD8

HD9

HD10

HD11

HD12

67

83

67

44

44

9-16-9(25)

12-15-7(22)

12-10-7(17)

7-6-7(13)

11-10-8(18)


10:05 AM.

MC = 10%LMA


MC = 12%SA



10:50 AM.


11:05 AM.

SM

SP-SM

SW-SM

35.0

40.0

51.5

SILTY SAND WITH GRAVEL, (SM) 38% gravel, 44% sand, 12% fines, brown,subangular, fine to coarse grained, wet, up to 1.5" particle size. (continued)

POORLY GRADED SAND WITH SILT AND GRAVEL, (SP-SM) 25% gravel,67% sand, 8% fines, brown, subangular, fine to coarse grained, wet, up to 2"particle size.

WELL GRADED SAND WITH SILT AND GRAVEL, (SW-SM) 40% gravel, 52%sand, 8% fines, brown, subangular, fine to coarse grained, wet, up to 2" particlesize.

Bottom of borehole at 51.5 feet.

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HD1

HD2

HD3BHD3A

HD4AHD4B

HD5

HD6

HD7

67

89

100

100

100

83

89

89

67

6-4-3(7)

7-10-8(18)

1-10-10(20)

8-16-50/5"

56-33-21(54)

18-14-12(26)

17-18-24(42)


12:10 PM.

MC = 19%SA

Sample taken at12:20 PM.

PP = 0.5 tsfMC = 34%

Sample Taken at12:30 PM.MC = 9%

PP = 0.5 tsfMC = 17%

Sample taken at12:40 PM.MC = 10%

Possible rockChatter on auger

MC = 5%SA


MC = 14%LMA


Water table


1:13 PM.

GW-GM

ML

GP-GM

ML

GW-GM

GP-GM

SP-SM

7.5

8.5

10.0

11.0

21.0

25.0

WELL GRADED GRAVEL WITH SILT AND SAND, (GW-GM) 47% gravel,44% sand, 9% fines, gray, subangular, fine to coarse grained, moist, up to 1.5"particle size. Organic root in sample 2.

SANDY SILT, (ML) gray, moist, non plastic

POORLY GRADED GRAVEL WITH SILT AND SAND, (GP-GM)

SANDY SILT, (ML) non plastic

WELL GRADED GRAVEL WITH SILT AND SAND, (GW-GM) 56% gravel,35% sand, 9% fines, gray, subangular, fine to coarse grained, moist, up to 2"particle size.

POORLY GRADED GRAVEL WITH SILT AND SAND, (GP-GM) 52% gravel,37% sand, 11% fines, brown, subangular, fine to coarse grained, wet, up to 2"particle size.

POORLY GRADED SAND WITH SILT AND GRAVEL, (SP-SM)


GROUND ELEVATION

LOGGED BY SMH




CHECKED BY SMH/MCH




AFTER DRILLING ---


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PROJECT NAME Lot 17




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REMARKS U.S

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HD8

HD9

HD10

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HD12

33

67

67

78

67

9-7-5(12)

26-18-14(32)

11-10-8(18)

11-8-5(13)

8-7-6(13)


1:25 PM.


1:44 PM.


2:0 PM.

MC = 12%SA


MC = 10%sample taken at

2:33 PM.

SP-SM

SP-SM

45.0

51.5

POORLY GRADED SAND WITH SILT AND GRAVEL, (SP-SM) (continued)

WELL GRADED SAND WITH SILT AND GRAVEL, (SP-SM) 15% gravel, 73%sand, 12% fines, brown, subangular, fine to coarse grained, wet, up to 1.5"particle size.


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HD1

HD2

HD3

HD4AHD4B

HD5

HD6

HD7

67

44

56

100

100

89

0

89

8-7-6(13)

4-4-3(7)

3-2-4(6)

7-15-23(38)

16-21-32(53)

48-55-1(56)

6-7-9(16)

Lots of chatter onauger.


8:05 AM.


8:13 AM.

MC = 29%LMA, ATT


PP = 0.3 tsfMC = 14%

Sample taken at8:25 AM.MC = 9%


8:35 AM.Lots of chatter.


Lots of chatter onauger; cobbles /

14" boulderChatter stopped at

22'

MC = 12%LMA


GP-GM

SM

GP-GM

GP-GM

7.5

11.0

14.0

30.0


SILTY SAND WITH GRAVEL, (SM) 18% gravel, 62% sand, 20% fines, brown,moist, non plastic


POORLY GRADED GRAVEL WITH SILT AND SAND, (GP-GM) 62% gravel,31% sand, 7% fines, brown, fine to coarse grained, wet, up to 2" particle size.


GROUND ELEVATION

LOGGED BY SMH




CHECKED BY SMH/MCH




AFTER DRILLING ---


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HD8

HD9

HD10

HD11

HD12

89

44

44

44

67

17-12-8(20)

13-6-5(11)

11-8-8(16)

9-5-5(10)

4-4-4(8)

MC = 12%SA


~6" heave.MC = 11%



10:00 AM.

~6" heave.MC = 22%


No heave.MC = 78%

LMASample taken at

10:25 AM.

SM

SM

50.0

51.5

SILTY SAND WITH GRAVEL, (SM) 19% gravel, 61% sand, 20% fines, brown,fine grained, wet, up to 0.5" particle size.

SILTY SAND, (SM) 7% gravel, 78% sand, 15% fines, brown, wet, organics


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APPENDIX C

Site Investigation Photos

21201.02 CBS Lot 17 Figure

June 2018 Site and Investigation Photographs C-1

PHOTO Lot 17 (looking North-Northeast)



PHOTO Lot 17 (looking North-Northwest)



PHOTO Debris on site



PHOTO Drilling on BH-01



PHOTO Setting up on BH-02



PHOTO Drilling on BH-03



PHOTO Penetrometer P-3



PHOTO Demobilizing the drill rig

APPENDIX D

Laboratory Results

W.O. #

Lab #

All results will be posted to the website for your access and convenience. Samples will be kept for

30 days before being disposed. Please contact us if you would like the remaining material returned.

BH01 Sample 1

BH01 Sample 2A

BH01 Sample 2B

BH01 Sample 3A

BH01 Sample 3B

BH01 Sample 4

BH01 Sample 5

BH01 Sample 6

BH01 Sample 7

BH01 Sample 8

BH01 Sample 9

BH01 Sample 10

BH01 Sample 11

BH01 Sample 12

BH02 Sample 1

BH02 Sample 2

BH02 Sample 3A

BH02 Sample 3B

BH02 Sample 4A

BH02 Sample 4B

BH02 Sample 5

If you have questions regarding this summary report or the test procedures, please contact us.

OscarOscar Lage

Testing Report Summary

Date Sample Recv'd 6/4/2018

Client CRW 158

Project CBS Filtration Evaluation 194

Location BH01 to BH03

Results (%)

Test PerformedMoisture Content, ASTM D2216

BH02 Sample 6 14

Results (%)Sample ID

BH02 Sample 7

BH02 Sample 8

BH02 Sample 11

6

10

38

13

6

9

BH02 Sample 9

BH02 Sample 10

12

11

14

9

10

BH02 Sample 12

BH03 Sample 1

BH03 Sample 2

BH03 Sample 3

BH03 Sample 4A

9

34

BH03 Sample 4B

BH03 Sample 5

BH03 Sample 7

BH03 Sample 8

BH03 Sample 9

BH03 Sample 10

BH03 Sample 11

12

11

13

8

19

8

12

10

12

10

9

9

29

14

9

Sample ID

5

BH03 Sample 1217

10

12

11

10

22

78

9

9

9

Laboratory Supervisor

W.O. #

Lab #

All results will be posted to the website for your access and convenience. Samples will be kept for

30 days before being disposed. Please contact us if you would like the remaining material returned.

BH01 4 (ATL#196)

BH01 S9 (ATL#198)

BH02 S6 (ATL#202)

BH03 S3 (ATL#204)

BH03 S7 (ATL#205)

BH03 S12 (ATL#207)

If you have questions regarding this summary report or the test procedures, please contact us.

OscarOscar Lage

Laboratory Supervisor

Testing Report Summary

Date Sample Recv'd 6/4/2018

Client CRW 158

Project CBS Filtration Eval 196 to 207

Location BH01 to BH03

Results (%)Gravel Sand

Test PerformedLimited Mechanical Analysis

42 9

Silt

67

37

78

49

25

52

18

62

7

62

31 7

15

Sample ID

8

11

20

Client:

Project:

Work Order:

CRW Engineering Group, LLC


158

6/4/2018

2018-195Lab Number

Received

Reported 6/13/2018

Size Passing Specification

3" 100%

2" 100%

1½" 95%

1" 82%

¾" 75%

½" 62%

⅜" 55%

#4 42%

Total Weight of Sample 2251.5g

#10 30%

#20 21%

#40 16%

#60 13%

#100 10%

#200 8.1%

Total Weight of Fine Fraction 951g

ASTM D422

Particle Size Distribution

Engineering Classification:

Frost Classification:

Well Graded Gravel with Silt and Sand, GW-GM

Not Measured

Location: BH01 S1

Client:

Project:

Work Order:



158

6/4/2018

2018-197Lab Number

Received

Reported 6/13/2018


3" 100%

2" 100%

1½" 100%

1" 88%

¾" 85%

½" 79%

⅜" 74%

#4 61%


#10 46%

#20 34%

#40 27%

#60 23%

#100 20%

#200 16.5%

Total Weight of Fine Fraction 348.1g

ASTM D422




Silty Sand with Gravel, SM

Not Measured

Location: BH01 S7

Client:

Project:

Work Order:



158

6/4/2018

2018-199Lab Number

Received

Reported 6/13/2018


3" 100%

2" 100%

1½" 91%

1" 87%

¾" 86%

½" 80%

⅜" 73%

#4 60%


#10 43%

#20 27%

#40 19%

#60 15%

#100 11%

#200 7.5%


ASTM D422




Well Graded Sand with Silt and Gravel, SW-SM

Not Measured

Location: BH01 S10

Client:

Project:

Work Order:



158

6/4/2018

2018-200Lab Number

Received

Reported 6/13/2018


3" 100%

2" 100%

1½" 99%

1" 94%

¾" 87%

½" 75%

⅜" 69%

#4 53%


#10 39%

#20 28%

#40 21%

#60 16%

#100 12%

#200 9.0%


ASTM D422





Not Measured

Location: BH02 S2

Client:

Project:

Work Order:



158

6/4/2018

2018-201Lab Number

Received

Reported 6/13/2018


3" 100%

2" 100%

1½" 87%

1" 80%

¾" 72%

½" 64%

⅜" 59%

#4 44%


#10 32%

#20 23%

#40 17%

#60 14%

#100 11%

#200 8.8%


ASTM D422





Not Measured

Location: BH 02 S5

Client:

Project:

Work Order:



158

6/4/2018

2018-203Lab Number

Received

Reported 6/13/2018


3" 100%

2" 100%

1½" 100%

1" 97%

¾" 97%

½" 94%

⅜" 92%

#4 85%


#10 70%

#20 44%

#40 28%

#60 20%

#100 16%

#200 11.9%


ASTM D422




Well Graded Sand with Silt and Gravel, SW-SM

Not Measured

Location: BH02 S11

Client:

Project:

Work Order:



158

6/4/2018

2018-206Lab Number

Received

Reported 6/13/2018


3" 100%

2" 100%

1½" 100%

1" 100%

¾" 100%

½" 100%

⅜" 98%

#4 81%


#10 59%

#20 44%

#40 35%

#60 29%

#100 25%

#200 20.4%


ASTM D422




Silty Sand with Gravel, SM

Not Measured

Location: BH03 S8

APPENDIX E

Drive Penetrometer Data


July 2018 Drive Penetrometer Data E-1

Depth (ft) BPF

1 33

2 31

3 19

4 20

5 98

6 14

7 22

8 25

9 95

10 164

11 72

12 103

13 120

14 82

15 59

16 72

17 40

18 30

19 27

20 26

21 45

22 43

23 45

24 41

25 39

26 32

27 22

P-1

Depth (ft) BPF

28 23

29 27

30 30

31 34

32 24

33 24

34 26

35 23

36 26

37 21

38 20

39 20

40 16

41 22

42 23

43 20

44 22

45 18

46 17

47 18

48 20

49 18

50 23

51 25

52 21

53 23

54 27

P-1



Depth (ft) BPF

1 20

2 45

3 36

4 32

5 30

6 21

7 8

8 8

9 13

10 33

11 48

12 54

13 78

14 63

15 100

16 79

17 71

18 46

19 41

20 32

21 30

22 36

23 22

24 36

25 31

26 27

27 31

28 30

29 26

30 16

31 23

32 21

33 15

34 23

35 19

36 23

37 23

P-2

Depth (ft) BPF

38 21

39 19

40 15

41 27

42 28

43 21

44 20

45 17

46 24

47 22

48 26

49 27

50 17

51 27

52 29

53 24

54 26

55 29

56 36

57 35

58 26

59 33

60 29

61 45

62 55

63 49

64 95

65 58

66 60

67 61

68 47

69 107

70 78

71 76

72 54

73 51

P-2



Depth (ft) BPF

28 46

29 32

30 23

31 20

32 17

33 21

34 19

35 17

36 15

37 13

38 12

39 17

40 18

41 16

42 16

43 18

44 17

45 12

46 23

47 22

48 22

49 24

50 25

51 32

52 33

53 42

54 44

P-3

Depth (ft) BPF

1 35

2 20

3 26

4

5

6 15

7 5

8 5

9 11

10 56

11 53

12 66

13 58

14 117

15 156

16 106

17 150

18 119

19 106

20 54

21 74

22 36

23 137

24 48

25 35

26 51

27 39

P-3

* Penetrometer drilled out

*

*

Geotechnical Report Critical Secondary Water Supply

Sitka, Alaska

September 2018

Submitted To: CRW Engineering Group, LLC

3940 Arctic Blvd, Ste. 300 Anchorage AK 99503

By:

Shannon & Wilson, Inc. 5430 Fairbanks Street, Suite 3

Anchorage, Alaska 99518 AECC125

Phone: (907)561-2120

Fax: (206)695-6777

E-mail: [email protected]

100427-001


SHANNON & WILSON, INC.

Sitka Waterline Georeport.Doc 100427-001 i

TABLE OF CONTENTS

1.0 INTRODUCTION .................................................................................................................1 2.0 SITE AND PROJECT DESCRIPTION ................................................................................1 1.0 REGIONAL GEOLOGY, TECTONICS, AND SEISMICITY ............................................2

1.1 Regional Geology ......................................................................................................2 1.2 Tectonics ...................................................................................................................3 1.3 Seismicity ..................................................................................................................3

3.0 SITE VISIT ...........................................................................................................................4 3.1 Observation Point 1 ...................................................................................................4 3.2 Observation Point 2 ...................................................................................................4 3.3 Observation Point 3 ...................................................................................................5 3.4 Observation Point 4 ...................................................................................................5 3.5 Bedrock and Structure Mapping ................................................................................6

4.0 SLOPE STABILITY .............................................................................................................6 4.1 Soil Slopes .................................................................................................................6 4.2 Rock Slopes ...............................................................................................................7

5.0 RECOMMENDATIONS ......................................................................................................7 5.1 Route Selection ..........................................................................................................8 5.2 Upland Route .............................................................................................................8 5.3 Lowland Route ........................................................................................................10 5.4 Structural Fill and Compaction ...............................................................................11

6.0 CLOSURE AND LIMITATIONS ......................................................................................11

LIST OF FIGURES Figure 1 Vicinity Map Figure 2 Site Plan Figure 3 Gradation and Durability Requirements

LIST OF APPENDICES

Appendix A Photo Pages Appendix B Kinematic Analysis Results Appendix C Important Information About Your Geotechnical/Environmental Report


Sitka Waterline Georeport.Doc 100427-001 1

GEOTECHNICAL REPORT CRITICAL SECONDARY WATER SUPPLY

SITKA, ALASKA

1.0 INTRODUCTION

This report presents the results of geotechnical studies for a planned new secondary water supply line for the City of Sitka. We understand that two potential alignments for the water line are currently being considered, each of which will carry water from Sawmill Creek to existing public water supply works north of the Gary Paxton Industrial Park. Each water line alignment will require development on or at the toe of existing rock slopes adjacent to Sawmill Creek. The purpose of this study was to conduct a site visit to evaluate existing slope conditions, evaluate soil and rock slope stability along the alignment corridors, and provide engineering recommendations for the proposed improvements. Included in this report are results of our site visit, slope evaluation, and geotechnical engineering analyses and recommendations for the project.

Authorization to proceed with the field work was received in the form of a signed letter of authorization from Mr. Pete Bellezza of CRW Engineering Group, LLC on May 29, 2018. Our work was conducted in general accordance with our May 7, 2018 proposal.

2.0 SITE AND PROJECT DESCRIPTION

The project consists of designing a new water line to provide a secondary water supply for the City of Sitka. The secondary supply is needed to supply water while the City’s primary water supply (discharge from the Blue Lake Hydroelectric Facility) is down periodically for maintenance. In general, the project will include developing an intake in Sawmill Creek and a new water line that will feed planned and existing water supply works at the end of the Blue Lake Hydroelectric Facility discharge area. The two routes being considered for this project include an upland route piping the water from an intake structure up and out of the Sawmill Creek canyon and a lowland route following the base of the canyon slopes (lowland route). The project vicinity is shown on Figure 1 and the general project layout including the major project components and approximate route alternative corridors are included on Figure 2.

The project is located in a deep canyon section of Sawmill Creek north of the Gary Paxton Industrial Park in Sitka, Alaska. The canyon is incised up to approximately 80 feet deep with steep rock slopes on either side of the creek. Within the project limits, Sawmill Creek generally flows from east to west and then takes an abrupt turn to the south before flowing under Green Lake Road. The base of the canyon is approximately 100 to 150 feet wide and the upland areas



to the east have been developed with industrial water treatment works that have been abandoned ed for more than 20 years. Development of these areas included clearing and grading (through rock blasting to create benches) and installation of drainage flumes (some of which are still conveying water). There are also areas in the upland developed areas where significant fills (consisting of rock debris and landfill material) have been deposited. Much of the prior development has been overgrown with vegetation.

1.0 REGIONAL GEOLOGY, TECTONICS, AND SEISMICITY

Southeast Alaska lies within the active tectonic belt that rims the northern Pacific Basin. Plate tectonic activity since the late Paleozoic time has resulted in northwesterly trending bands of folded sedimentary, igneous and metamorphic rocks. Granitic batholiths emplaced during the mid to late Cretaceous period, are widespread throughout southeast Alaska and form the backbone of the Coast Range. The major lineaments in southeast Alaska, such as fjords and river valleys are believed to be controlled by major faults or fault zones.

1.1 Regional Geology

The regional geology is dominated by the Chugach Terrane which is a lower-Jurassic to Upper-Cretaceous flysch and includes intensely folded and weakly metamorphosed graywackes, shales and volcanic rocks. The Kelp Bay Group and the Sitka Group are included in this terrane. There are also numerous Tertiary plutons which provide occasional igneous rocks including gabbro and quartz diorite. The local rocks are generally both sedimentary and volcanic metamorphosed rocks which have been subjected to low to moderate pressures and temperatures during mountain building and terrain accretion processes. The Kelp Bay Group is a tectonic patchwork of late Mesozoic, metamorphosed sedimentary and volcanic rock including greenschist, phyllite, greenstone, tuff, and graywacke. The Sitka Group consists mainly of slate and Sitka graywacke, but also includes minor amounts of conglomerate, greenstone, and limestone. It is characterized by thin to medium bedded interstratified graywacke, argillite, and slaty argillite. The Sitka graywacke is a poorly sorted, fine to coarse grained, low grade metamorphic interbedded with hard mudstone. Hornfels is also found at contact areoles between the plutonic intrusions and the Sitka graywacke.

Mount Edgecumbe is a dormant composite cone volcano on Kruzof Island, visible from Sitka and approximately 19 miles away from Sawmill Cove. An eruption 9,000 years ago deposited 1 to 2 inches of ash in Sitka and thinner layers in Juneau. Areas of thicker ash deposits can be found throughout the region in localized accumulation zones. Mount Edgecumbe has been inactive for the past 200 years. The Mount Edgecumbe volcanic field is about 100 square miles and contains basalt, andesite and rhyolite domes.



Glaciers advanced over the region during the Pleistocene Epoch (~10,000 to 2 million years ago) leaving undifferentiated drift deposits that typically consist of till and other glacially deposited material. These deposits typically have a wide range of grain size and may be classified as sands, gravels, silts or even clays depending upon the exact mechanism of deposition. Many of the landforms in this area have been influenced by glacial advance and retreat. Quaternary deposits also include lacustrine, fluvial, beach, and shallow marine sediments. Other shoreline surficial deposits consist of modern beach sediment, estuarine, stream alluvium, muskeg, and colluvium.

1.2 Tectonics

An intricate network of reverse, normal and strike-slip faults dissects southeastern Alaska. The Queen Charlotte-Fairweather fault system lies to the west of Sitka. This system is known to be an “active” right-lateral strike slip fault with large displacements. The location of this fault, which represents the transform boundary between North America and the Pacific Plate, is approximately 25 to 50 miles west of Sitka and boasts four major earthquakes in the last century. On the east side of Baranof Island is the Chatham Strait fault, which is the second largest right lateral strike-slip fault in southeast Alaska and was active in the Tertiary Period (2 to 65 million years ago). This fault has shown right lateral displacement of up to 93 miles and is thought to truncate in the south into the Queen Charlotte-Fairweather fault. Numerous other faults crisscross the region but are thought to be inactive.

The project is located within the Silver Bay segment of the Sitka fault zone, one of several major fault zones in northern Southeast Alaska. According to Brew (1991), the Sitka fault zone is a high angle fault zone approximately 200-kilometers in length, and containing several faults and fault segments. The Silver Bay segment, the southern portion of the larger Neva Strait fault, is about 40 kilometers long and ranges between 0.4 and 2 kilometers wide. The segment contains between two and five discernible fault strands and includes a wide variety of rock types and units, which illustrate the complexity of faulting in the region. Although obscured by multiple periods of movement, inferred displacements within the Silver Bay segment are thought to be on the order of about 20 km left-lateral (sinistral) separation. The history of movements in the fault zone are thought to begin with mid-Cretaceous compression of the Chugach terrane rocks against Wrangellia terrane rocks, with the most recent movements thought to be long-lived but intermittent Tertiary transcurrent (steeply inclined strike-slip) movements.

1.3 Seismicity

The region is among the most seismically active areas in the United States and historically subjected to large (greater than 6.0 Magnitude) earthquakes. Alaska experiences approximately



22,000 earthquakes of any given magnitude per year, which accounts for 52 percent of the earthquakes in the United States (AEIC no date).

Large earthquakes in the region include a 1927 magnitude 7.1 earthquake near the northern portion of Chichagof Island, a 1949 magnitude 8.1 event recorded along the Queen Charlotte fault near the Queen Charlotte Islands (Haida Gwaii), a 1958 magnitude 7.9 earthquake along the Fairweather fault near Lituya Bay, a 1972 magnitude 7.4 earthquake near Sitka, a 2004 magnitude 6.8 earthquake along the Fairweather fault south of Sitka, a 2012 magnitude 7.8 near the southern end of the Haida Gwaii, and in 2013 a magnitude 7.5 north of Haida Gwaii. These events appear to be located in and associated with the plate transform boundary to the west of Sitka. Reports indicate that Sitka experienced Modified Mercalli Intensity VI ground shaking for the 1949 event and an Intensity III for the 2004 event. Although a magnitude 5.3 event was located near the Chatham Strait fault in 1987, very few earthquakes in the area appear to have been directly related to this fault.

3.0 SITE VISIT

On June 1 and 2, 2018, an engineering geologist from Shannon & Wilson’s Anchorage office conducted a site visit to observe the surface and slope conditions at the site. The approximate locations of the observation points are included on the site plan in Figure 2 and the observations at the individual observation points are included below. Photographs collected during our site visit are included in Appendix A.

3.1 Observation Point 1

Observation Point 1 (OP-1) is located at the top of the access road, east of the abandoned water treatment plant, east of Sawmill Creek. Photos from the area are provided on Figures A-1 through A-3. The outfall flume for the abandoned water treatment plant runs along the east end of the building, creating a waterfall that flows into Sawmill Creek. East of the waterfall is an old landfill feature that appears to have been in place for an extended amount of time. The landfill feature has been undermined by Sawmill Creek below and a recent slide had occurred exposing a range of mineral soil, rock and buried construction debris. Along the hillside to the east of the treatment plant, a significant deposit of shot rock material that we understand are spoils from recent construction activities for the Blue Lake Hydroelectric facility.


Observation Point 2 (OP-2) is located in the benched area west and north of the abandoned water treatment plant, photographs from these areas are included in Figures A-4 and A-5. The benched area has been overgrown with spruce, birch, and alders, that appeared to have been a level gravel



pad during original development. Several exposures where storm water runoff has eroded soils near the crest of the canyon slopes have exposed soils up to 10 to 15 feet thick, with the thickest soil deposits on the north and east end of the pad. There are several pipes and penetrations near the base of the walls of the abandoned water treatment plant, most of which were producing water flow that was being directed toward the canyon and over the slope face to the north and west. Soil exposed at the top of the canyon slope typically consisted of gravel with sand and silt and appeared to originate from an alluvial source with rounded gravels.


Observation Point 3 (OP-3) is located in the canyon bottom in the east to west flowing portion of Sawmill Creek, photographs from these areas are included in Figures A-6 and A-7. From this location, the waterfall feature flowing from the water treatment plant is flowing into Sawmill Creek and the debris from the recent slide of landfill debris can be seen. The canyon walls on either side of Sawmill Creek are steep, nearly vertical and the north wall comes down near the edge of the stream. Canyon slopes on the south wall are set back from the edge of the stream up to approximately 50 feet. In many areas, the toe of the rocky canyon’s south wall is obscured by large rock debris, with rocks as large as approximately 6 feet in diameter. Some isolated areas of soil slide debris were also observed. The debris (with the exception of the landfill debris north of the waterfall) is overgrown with relatively thick alder vegetation. Additionally, much of the rock debris at the base of the canyon slopes does not appear to be the result of deposition from rock slope failure. It is our opinion that most of the rock debris found at the base of the canyon slopes was likely deposited by side-casting the debris over the canyon slope during development of the water treatment plant above.


Observation Point 4 (OP-4) is located in the canyon bottom in the north to south flowing portion of Sawmill Creek, photographs from these areas are included in Figure A-8. The canyon walls along this reach of Sawmill Creek are similar to those described in OP-3, however the canyon slopes are slightly shallower, more overgrown and there is less large boulder debris at the toe of the slope. Based on the width of the canyon, steepness of the rock slopes on either side, and the apparent lack of bedrock exposure in the stream bed, it is our opinion that the alluvium in the canyon bottom is likely greater than 5 feet. Alluvial material exposed on the surface appeared relatively clean (low fines content) and consisted of poorly graded gravel with sand. The alluvium contained rounded cobbles and boulders up to approximately 4 feet in diameter. The soils in the bed of Sawmill Creek also contained a significant amount of debris that we assume is from prior development in and above the creek, as well as from landfill debris sliding into the



creek upstream of the waterfall. Debris consisted of wood, concrete, and metal fragments of a wide range of types and sizes.

3.5 Bedrock and Structure Mapping

The rock exposed in and around the canyon walls appeared to consist of metamorphosed sedimentary rock, consisting primarily of argillite and graywacke. The rock was generally characterized by relatively massive structure with no apparent foliation and significant shear or gouge zones. The visible structure and canyon slope walls appeared to be controlled by two steeply dipping joint sets, oriented approximately perpendicularly to each other, with other minor, less dominant joints randomly distributed through the rock mass.

Our engineering geologist conducted rock structure mapping at five stations (RS-1 through RS-5) along the Sawmill Creek Canyon wall. It should be noted that the measurements were only taken on the south (east-west oriented) wall of the canyon as there were no significant rock exposures from which structure measurements could be taken on the east (north-south oriented) wall. The approximate mapping points are indicated on the site plan in Figure 2. We collected rock mass structure information using the cell mapping technique as described by Hustrulid and others, 2000. This method includes the collection of structure (e.g. bedding, foliation, shear zones, joint sets, etc.) as well as other information such as feature length, persistence, separation, and roughness to characterize the rock mass for the purposes of slope stability evaluation and designing slope stabilization. Stereo plots of the rock structure mapping conducted during our site visit, along with kinematic analysis results are presented in Appendix B.

4.0 SLOPE STABILITY

An evaluation of slope stability for development in this site should include consideration for both soil and rock slopes. A mantle of presumably man-made gravel fills exists on the benches above the creek and rock slopes that comprise the canyon walls are relatively steep.

4.1 Soil Slopes

Soils placed around the abandoned water treatment appear to consist of either gravel fills placed for the creation of the pad around the building, or landfill debris and shot rock waste placed north of the water treatment plant and waterfall feature. Based on the unknown thickness, nature, and recent sliding of the latter, it is our opinion that those slopes are marginally stable and disturbance through development could further destabilize these slopes. Gravel fills placed around the north and west sides of the water treatment plant that create the overgrown pad appear to be relatively stable, except for a few isolated areas where erosion has created minor sloughing down the canyon slopes. By comparison, these soils appear to be significantly thinner than the



landfill and shot rock debris (not more than approximately 15 feet thick based on visual estimates) and can likely be controlled through grading if disturbed by development.

4.2 Rock Slopes

The results of our kinematic stability analysis are presented in Appendix B. The plot sets in Figures B-1 through B-4 present kinematic analyses for the east-west oriented canyon wall and the plot sets in Figures B-5 through B-8 show the same analyses for the north-south oriented canyon wall. The purpose of the analyses is to evaluate the potential for kinematically admissible planar, wedge, and toppling failures based on slope geometry and structure orientation. In general, the kinematic analyses show that the face of the east-west oriented wall is controlled by a dominant, steeply dipping joint set (Joint Set JS-1) and that the north-south oriented canyon wall is controlled by the steeply dipping Joint Set JS-2, which is roughly perpendicular to JS-1. The lower angle joint set (Joint Set JS-3) shown on the stereo plot was most prevalent in and around the waterfall area and appeared to create a stair-stepped feature in some areas. Our analyses suggest that wedge failures are kinematically admissible on the east-west oriented canyon wall and planar failures are kinematically admissible on the north-south oriented wall. Though our analyses suggest that planar failures are not admissible on the east-west oriented wall, we believe that they are a potentially admissible with slight changes in slope orientation and should be considered when developing near the slope.

While the kinematic analysis suggests the potential for slope failure, rock slopes observed during our site visit appeared to be relatively stable as signs of recent large scale failures were not observed. While the potential for these types of failures is geometrically possible, we believe that the risk for large scale wedge or planar failures is relatively low. It is our opinion that the most likely failures in the canyon walls will consist of occasionally raveling as rock fragments are released from the face. Rockfall will likely be limited to material no greater than 12 inches in diameter.

5.0 RECOMMENDATIONS

The recommendations included below address general route selection considerations as well as design parameters for each potential route. The approximate alignment corridors are provided in on the site plan in Figure 2. We understand that the actual alignment has yet to be determined and that it may not follow the exact corridors shown on the site plan. We recommend that once a final alignment is selected, that we be allowed to revisit our recommendations to evaluate their applicability and adjust them if necessary.



5.1 Route Selection

Two general alignments being considered for this project are the upland and lowland routes as described above. The upland route will require significant structural features to carry the water line up the existing rock face necessitating incorporating rock stabilization measures to ensure long-term viability of the line. The lowland route will require the pipe to be protected from erosion and rockfall from the canyon slopes above.

Each of the proposed alignments will require development on or below existing rock slopes. Individual recommendations for each route are provided below, but regardless of the route selected, some common components should be incorporated into the design and construction of the project. Wherever the new pipe traverses within 25 feet of the toe of the rock slope or is constructed on the rock slope, inspection and hand scaling should be conducted prior to and after construction to remove loose rock fragments. In addition, existing vegetative cover on the slopes should be disturbed to the least extent practicable. Where possible, surface water should be re-routed and directed to the south or to the drainage flume that feeds the waterfall such that it is discouraged from flowing over the rock face. In addition, fill soils in the pad area around the water treatment plant should be pulled back and graded to slopes not steeper than 2 horizontal (H) to 1 vertical (V). These measures should improve the overall stability of the slope and its long term performance and reduce the risk of material falling downhill and impacting the water line. If rock slopes are to be re-shaped from their existing condition, they should be established at angles no steeper than 70 degrees from horizontal.

After construction of either pipeline route, the rock slopes will require periodic inspection. The areas around the pipe should be examined for evidence of rock fall. Occasional hand scaling may be needed for periodic maintenance if increased rockfall is observed in the rock slopes. Hand scaling should be conducted by an experienced contractor using scaling bars to remove loose rock fragments from the rock face in a controlled manner. Scaling should be limited to loose rock fragments that are generally less than 12 inches in diameter and the pipeline should be protected from scaled rock during scaling activities. If larger rock fragments are identified during scaling activities, alternative mitigation methods (e.g. controlled blasting, trim blasting, mechanical stabilization, etc.) and overall slope stability should be evaluated on an as needed basis.

5.2 Upland Route

The primary feature of the upland route is the portion of the alignment that travels up the existing canyon rock face near the waterfall feature. Based on our field observations, it is our opinion that the optimum location for carrying the pipe up the rock slope is near Rock Structure Mapping



Station RS-2, to the west of the waterfall feature. Running the pipe up the rock slope will require a structural connection between the pipe support members and the rock wall. The structural connection should consist of tensioned rock anchors that can also provide stabilization of the rock face in the immediate area of the pipe alignment. As stated in Section 4.2, the primary stability concern in the likely alignment is plane shear failures along the dominant joint set that dips down steeply to the north.

Designing the tensioned rock anchors (i.e. diameter of the rods and pre-tension loads) will depend on the type of pipe support and spacing of that support up the rock slope, which are not known at the time of this report. However, we anticipate that the anchors will likely consist of 1.5 to 3-inch threaded bars that will need to penetrate a minimum of 30 feet into the rock face with a minimum free-bonded length of 10 feet. Anchor embedment will be designed to resist the calculated, factored loads from the pipe as well as loading required for stabilization using allowable bond strength between the grout and rock of 125 pounds per square inch (psi). These values assume that the anchor holes are drilled with a percussion type rock drill and the contractor is able to obtain drill holes that are largely clear of debris. The value may need to be adjusted depending on drilling techniques, if zones of loose or fractured rock are encountered, or if the drill cuttings become smeared on the drill hole walls. Additionally, the anchors should be placed and grouted into a hole with a diameter between 2 to 2.5 times greater than the anchor diameter.

Once an alignment and support layout configuration have been developed, we will be able to determine the pre-tension loads that should be applied to the anchors, which will in-turn allow the structural engineer to determine the size the anchor bars. We recommend that the anchors installed for each foundation element be stress tested to verify their capacity. The testing should be conducted according to guidelines set forth by the Post-Tensioning Institute (PTI) in their Recommendations for Prestressed Rock and Soil Anchors. The anchors should incorporate the appropriate corrosion protection to ensure that they maintain capacity over the life of the structure. We recommend that a geotechnical engineer experienced in tensioned rock anchoring be retained to review the final plans and specifications to verify that the documents generally conform to the above recommendations.

Once the pipe has been run up the rock slope, the remainder of the upland portion of the line will require conventional subsurface or above ground pipe installation. Based on surface observations, excavations in the upland areas will likely encounter coarse gravel, shot rock, and bedrock. The contractor should be prepared for excavations in these difficult conditions that will likely require a combination of conventional earth working equipment, pneumatic hammers, and



potentially drill and blast methods. A minimum of 6 inches of Selected Material Type A should be used for pipe bedding, placed and compacted per the recommendations in Section 5.4.

5.3 Lowland Route

The lowland route will largely follow the base of the canyon walls, paralleling Sawmill Creek. At the time of this report, it is not known whether the pipe will be buried or installed above ground. Regardless of how the pipe is constructed in this route, the portion of the alignment in the canyon bottom will need to be protected from stream erosion, which we assume will be handled by others.

If the pipe is installed on above ground supports, it will need to be protected from potential rockfall from the slopes above the pipe. The most effective method of protection from rockfall will be through placing the pipe as far from the toe of the canyon wall slopes as possible. Based on our observations during our site visit and the height/angle of the slope, we believe that placing the pipe 25 feet from the toe of the canyon wall slope should prevent rockfall from impacting the pipe. If this is not possible, barriers may be placed between the pipe and the slope for additional rockfall protection. Barriers may consist of boulders at least approximately 4 feet in diameter and placed in a row approximately 2 feet from the upslope edge of the pipe. Minimum spacing between the boulders should be 2 feet, edge-to-edge.

Above ground support members for the pipe for this route will likely consist of precast concrete blocks. We recommend a minimum width of the concrete blocks of 12 inches and a minimum embedment of 2 feet below the ground surface. Assuming these dimensions, we recommend assuming a maximum allowable bearing capacity of 2,000 pounds per square foot, which may be increased by 1/3 for seismic loading. To resist lateral loading, we recommend assuming an equivalent fluid weight of 200 pounds per cubic foot and a friction coefficient of 0.4 on the base of the foundations. Backfill below and around foundations should consist of Selected Material Type A, placed and compacted as recommended in Section 5.4.

The pipe in the lowland alignment may also be installed below the ground surface using open trenching techniques. Note that we believe that groundwater and running ground conditions will prohibit installation of the pipe at an elevation lower than approximately 1 foot below the water level in Sawmill Creek. Based on surface observations, excavations in the lowland areas in the base of the canyon will likely encounter coarse gravel, boulders, and steel/concrete debris. Assuming a likely burial depth of approximately 5 feet, we believe that bedrock will not be encountered in the canyon base, unless the excavation is within approximately 10 feet of the canyon walls. During excavation in the bottom of the canyon, the contractor should be prepared to handle large boulders and debris in the excavations. Once the pipe is out of the canyon,



excavation conditions similar to those described in the upland route can be expected. The contractor should be prepared for excavations in these difficult conditions that will likely require a combination of conventional earth working equipment, pneumatic hammers, and potentially drill and blast methods. A minimum of 6 inches of Selected Material Type A should be used for pipe bedding, placed and compacted per the recommendations in Section 5.4.

5.4 Structural Fill and Compaction

Structural fill may be needed under or around pipe support foundations, as pipe bedding, and to backfill trench excavations. Structural fill placed in these areas should be clean, granular soil to provide drainage and frost protection. These soils should contain less than about six percent (by weight, based on the minus 3-inch portion) passing the No. 200 sieve. Select Material Type A as defined by the Alaska Department of Transportation Standard Specifications meets these requirements. Generally, these soils may be placed using moisture density control in both wet and dry conditions. Figure 6 summarizes the gradation requirements for the materials described above.

Structural fills should be placed in lifts not to exceed 10 to 12 inches loose thickness and compacted to 95 percent of the maximum density as determined by the Modified Proctor compaction procedure (ASTM D 1557). During fill placement, we recommend that cobbles with dimensions in excess of 8 inches be removed from structural fills. We recommend that our services be retained to inspect the quality of fill compaction during construction.

6.0 CLOSURE AND LIMITATIONS

This report was prepared for the exclusive use of our client and their representatives for evaluating the site as it relates to the geotechnical aspects discussed herein. The conclusions and recommendations contained in this report are based on information provided from the observed site conditions and other conditions described herein. The analyses, conclusions and recommendations contained in this report are based on site conditions as they presently exist. It is assumed that the surface observations are representative of the conditions throughout the site, i.e., the conditions everywhere are not significantly different from those disclosed by the surface observations.

Once a final design for the proposed improvements has been selected, Shannon & Wilson, Inc. should be advised at once so that these conditions can be reviewed and recommendations can be reconsidered where necessary. If there is a substantial lapse of time between the submittal of this report and the final design, or if conditions have changed due to natural causes or construction operations at or adjacent to the site, it is recommended that this report be reviewed to determine

VICINITY MAP

September 2018

FIG. 1100427-001

SHANNON & WILSON, INC.Geotechnical & Environmental Consultants

Critical Secondary Water SupplySitka, Alaska

Alaska Canada

Anchorage

Sitka

Map adapted from All Topo Maps, USGS Sitka A-4 SW & A-5 SE 25K Quadrangles

APPROXIMATE SCALE IN MILES

0 1 20.5

Lear

nard

G

laci

er

Project Location

GRADATION AND DURABILITY REQUIREMENTS

D1PERCENT PASSING

BY WEIGHTU.S. STANDARD SIEVE SIZE

1 in.3/4 in.3/8 in.No. 4No. 8No. 50No. 200

25 mm19 mm9.5 mm4.75 mm2.36 mm0.300 mm0.075 mm

10070 - 10050 - 8035 - 6520 - 508 - 300 - 6

English Metric

After: Alaska Department of TransportationStandard Specifications for Highway Construction

Coarse Aggregate Durability

L.A. AbrasionSulfate Soundness

45 - 50 max. *9 max.

Test Type Percent LossRetained on #4 Sieve

* Asphalt and Surface Course = 45% max Base Course = 50% max

Selected Material Type APERCENT PASSING


No. 4No. 200

4.75 mm0.075 mm

Selected Material Type BPERCENT PASSING


No. 200 0.075 mm 10 Max. on minus3-in. portion

20 - 556 Max. on minus

3-in. portion

English Metric

English Metric

SHANNON & WILSON, INC.Geotechnical & Environmental Consultants

Critical Secondary Water SupplySitka, Alaska

GRADATION AND DURABILITYREQUIREMENTS

September 2018

FIG. 3100427-001

Aggregate containing no muck, frozen material, roots, sodor other deleterious matter and with a plasticity index notgreater than 6 as tested by WAQTC FOP for AASHTOT 89/T 90. Meet the gradation as tested by WAQTC FOPfor AASHTO T 27/T 11.

Aggregate containing no muck, frozen material, roots, sod orother deleterious matter and with a plasticity index not greaterthan 6 as tested by WAQTC FOP for AASHTO T 89/T 90.Meet the gradation as tested by WAQTC FOP for AASHTOT 27/T 11.


100427-001

APPENDIX A

PHOTO PAGES

LIST OF FIGURES

Figure A-1 Photos 1 and 2 Figure A-2 Photos 3 and 4 Figure A-3 Photos 5 and 6 Figure A-4 Photos 7 and 8 Figure A-5 Photos 9 and 10 Figure A-6 Photos 11 and 12 Figure A-7 Photos 13 and 14 Figure A-8 Photos 15 and 16

Critical Secondary Water Supply Sitka, Alaska

September 2018 SHANNON & WILSON, INC. Geotechnical & Environmental Consultants A-1

PHOTOS 1 AND 2

Photo 2: OP-1, outfall flume above waterfall feature.

Photo 1: OP-1, looking north at shot rock fills placed north and east of abandon water treatment plant

100427-001



PHOTOS 3 AND 4

Photo 4: OP-1, soils exposed at top of canyon slope caused by water flowing as shown in Photo 3.

Photo 3: OP-1, looking south at penetration in water treatment plant north wall penetration and water flow.

100427-001



PHOTOS 5 AND 6

Photo 6: OP-1, rock exposed at top of canyon slope near end of erosional feature shown in Photo 5.

Photo 5: OP-1, gravelly soils exposed in an erosional feature that appears to be caused by water that once flowed from a water treatment plant wall penetration.

100427-001



PHOTOS 7 AND 8

Photo 8: OP-2, looking south at typical upper slope conditions on east side of treatment plant building. Very little rock exposure and dense tree growth.

Photo 7: OP-2, looking south at apparent overgrown gravel pad on west side of water treatment plant building.

100427-001



PHOTOS 9 AND 10

Photo 10: OP-2, looking north at partially covered rock exposure near top of canyon wall slopes west of the treatment plant building.

Photo 9: OP-2, looking south at apparent overgrown fill slope on west side of treatment plant. Fill contains boulders up to 3 feet in diameter.

100427-001



PHOTOS 11 AND 12

Photo 12: OP-3, looking east at waterfall. Note low angle “stair-stepped jointing” from Joint Sets 1 and 3. Also note boulders on canyon floor, likely from treatment plant development.

Photo 11: OP-3, looking south at landfill slide scarp and debris pile north of waterfall.

100427-001



PHOTOS 13 AND 14

Photo 14: OP-3, looking west at typical rock exposure on canyon bottom for east to west flowing portion of Sawmill Creek. River gravels shown at bottom of photo are typical.

Photo 13: OP-3, looking south at canyon rock slope. Water running down slope face is from upland source shown in Photo 3.

100427-001



PHOTOS 15 AND 16

Photo 16: OP-4, looking south at typical debris and vegetative cover on edge of canyon floor.

Photo 15: OP-4, looking north at canyon rock slope. Limited rock exposure in the north to south flowing portion of Sawmill Creek. Alluvium shown is typical for canyon floor.

100427-001


100427-001

APPENDIX B

KINEMATIC ANALYSIS RESULTS

LIST OF FIGURES

Figure B-1 Stereo Plot, East-West Oriented Canyon Slope Figure B-2 Planar Failure Analysis, East-West Oriented Canyon Slope Figure B-3 Wedge Failure Analysis, East-West Oriented Canyon Slope Figure B-4 Toppling Failure Analysis, East-West Oriented Canyon Slope Figure B-5 Stereo Plot, North-South Oriented Canyon Slope Figure B-6 Planar Failure Analysis, North-South Oriented Canyon Slope Figure B-7 Wedge Failure Analysis, North-South Oriented Canyon Slope Figure B-8 Toppling Failure Analysis, North-South Oriented Canyon Slope


32-1-01903

APPENDIX C

IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL/ENVIRONMENTAL REPORT

of 2 3/2004

SHANNON & WILSON, INC. Geotechnical and Environmental Consultants

Attachment to 100427-001 Date: September 2018 To: CRW Engineers, LLC Re: Critical Secondary Water Supply, Sitka,

Alaska

Important Information About Your Geotechnical/Environmental Report CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND FOR SPECIFIC CLIENTS. Consultants prepare reports to meet the specific needs of specific individuals. A report prepared for a civil engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consultant prepared your report expressly for you and expressly for the purposes you indicated. No one other than you should apply this report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose other than that originally contemplated without first conferring with the consultant. THE CONSULTANT'S REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. A geotechnical/environmental report is based on a subsurface exploration plan designed to consider a unique set of project-specific factors. Depending on the project, these may include: the general nature of the structure and property involved; its size and configuration; its historical use and practice; the location of the structure on the site and its orientation; other improvements such as access roads, parking lots, and underground utilities; and the additional risk created by scope-of-service limitations imposed by the client. To help avoid costly problems, ask the consultant to evaluate how any factors that change subsequent to the date of the report may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used: (1) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); (2) when the size, elevation, or configuration of the proposed project is altered; (3) when the location or orientation of the proposed project is modified; (4) when there is a change of ownership; or (5) for application to an adjacent site. Consultants cannot accept responsibility for problems that may occur if they are not consulted after factors, which were considered in the development of the report, have changed. SUBSURFACE CONDITIONS CAN CHANGE. Subsurface conditions may be affected as a result of natural processes or human activity. Because a geotechnical/environmental report is based on conditions that existed at the time of subsurface exploration, construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the consultant to advise if additional tests are desirable before construction starts; for example, groundwater conditions commonly vary seasonally. Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnical/environmental report. The consultant should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS. Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions in areas not sampled may differ from those predicted in your report. While nothing can be done to prevent such situations, you and your consultant can work together to help reduce their impacts. Retaining your consultant to observe subsurface construction operations can be particularly beneficial in this respect.

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A REPORT'S CONCLUSIONS ARE PRELIMINARY. The conclusions contained in your consultant's report are preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar with the background information needed to determine whether or not the report's recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant who developed your report cannot assume responsibility or liability for the adequacy of the report's recommendations if another party is retained to observe construction. THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnical/environmental report. To help avoid these problems, the consultant should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydrogeological, and environmental findings, and to review the adequacy of their plans and specifications relative to these issues. BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE REPORT. Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnical/environmental reports. These final logs should not, under any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/environmental report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared, and that developing construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because geotechnical/environmental engineering is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in their contracts, reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the consultant's liabilities to other parties; rather, they are definitive clauses that identify where the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions.

The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland