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FINALCity of Brockville WPCC Secondary Treatment Upgrade Selection of Secondary Treatment andDisinfection Technologies

Conceptual Design Report

February 2008

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BROCKVILLE WPCC SECONDARY TREATMENT UPGRADE SELECTION OF SECONDARY TREATMENT AND DISINFECTION TECHNOLOGIES CONCEPTUAL DESIGN REPORT – FINAL

Contents

1. Introduction ......................................................................................................................................1 1.1 Background..............................................................................................................................1 1.2 Project Objectives....................................................................................................................2 1.3 Project Scope ...........................................................................................................................2 1.4 Value Engineering ...................................................................................................................4

2. Existing Plant....................................................................................................................................7 2.1 Problem Statement...................................................................................................................7 2.2 Treatment Processes ................................................................................................................7 2.3 Flow Rates ...............................................................................................................................7 2.4 Certificate of Approval ............................................................................................................7

3. Design Basis.......................................................................................................................................8 3.1 Wastewater Flow and Characteristics......................................................................................8 3.2 Septage Receiving .................................................................................................................10 3.3 Effluent Criteria.....................................................................................................................10 3.4 Receiving Water ....................................................................................................................11

4. Secondary Treatment and Disinfection Technology Review ......................................................12 4.1 Approach to Evaluation .........................................................................................................12 4.2 Conceptual Design.................................................................................................................13 4.3 Secondary Treatment .............................................................................................................13

4.3.1 Design Basis .............................................................................................................13 4.3.2 Cost Analysis............................................................................................................17 4.3.3 Alternative Evaluation..............................................................................................18 4.3.4 Recommendation......................................................................................................18

4.4 Disinfection ...........................................................................................................................19 4.4.1 Design Basis .............................................................................................................19 4.4.2 Alternative Evaluation..............................................................................................19 4.4.3 Cost Analysis............................................................................................................20 4.4.4 Recommendation......................................................................................................21

5. Conceptual Design ..........................................................................................................................22 5.1 Treatment Processes and Process Sizing ...............................................................................22 5.2 Inlet Sewer.............................................................................................................................26 5.3 Septage Receiving .................................................................................................................26 5.4 Screening ...............................................................................................................................26 5.5 Grit Removal .........................................................................................................................26 5.6 Plant Hydraulics ....................................................................................................................26 5.7 Primary Treatment.................................................................................................................27 5.8 Biological Treatment .............................................................................................................27

5.8.1 Aeration System .......................................................................................................27 5.8.2 Secondary Clarification ............................................................................................27 5.8.3 RAS/WAS Pumping.................................................................................................28 5.8.4 Scum Removal .........................................................................................................28

5.9 Disinfection ...........................................................................................................................28 5.10 Outfall....................................................................................................................................29 5.11 Sludge Digestion ...................................................................................................................29 5.12 Dewatering of Biosolids ........................................................................................................30 5.13 Biosolids Management ..........................................................................................................30

6. Review of Existing Plant Upgrade/Rehabilitation Requirements ..............................................31 6.1 Screening ...............................................................................................................................31 6.2 Grit Removal .........................................................................................................................31 6.3 Primary Treatment.................................................................................................................31 6.4 Digestion and Dewatering .....................................................................................................31

7. Civil and Site Layout......................................................................................................................32 7.1 General ..................................................................................................................................32 7.2 Utilities ..................................................................................................................................32

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7.3 Construction Considerations..................................................................................................32 7.4 Landscaping...........................................................................................................................32

8. Instrumentation and Control ........................................................................................................33 8.1 Existing Control Systems ......................................................................................................33 8.2 PLC Considerations...............................................................................................................34 8.3 SCADA Considerations.........................................................................................................34 8.4 Instrumentation......................................................................................................................35 8.5 Control System Recommendations........................................................................................35

9. Architectural Design ......................................................................................................................37 9.1 General ..................................................................................................................................37 9.2 Operations and Staff Facilities...............................................................................................37 9.3 Design Codes and Standards .................................................................................................37

10. Structural Design............................................................................................................................38 10.1 General ..................................................................................................................................38 10.2 Design Codes and Standards .................................................................................................38 10.3 Materials ................................................................................................................................38

11. Electrical Design .............................................................................................................................39 11.1 Existing Power Distribution ..................................................................................................39 11.2 New Power Distribution ........................................................................................................39

11.2.1 Distribution...............................................................................................................40 11.2.2 Lighting ....................................................................................................................40 11.2.3 Emergency Supply....................................................................................................40 11.2.4 Power Factor Correction...........................................................................................40

12. Building Mechanical Design ..........................................................................................................41 12.1 Heating ..................................................................................................................................41 12.2 Ventilation .............................................................................................................................41 12.3 Odour Control........................................................................................................................41 12.4 Plumbing................................................................................................................................41 12.5 Life Safety .............................................................................................................................41

13. Implementation Schedule...............................................................................................................42 14. Project Costs ...................................................................................................................................43

14.1 Cost Estimating Basis and Assumptions ...............................................................................43 14.2 Impact of Escalation and Market Conditions.........................................................................44

14.2.1 Escalation to Time of Construction ..........................................................................44 14.2.2 Construction Market.................................................................................................44 14.2.3 Contingency Allowance ...........................................................................................44

15. Conclusions and Recommendations..............................................................................................45

List of Appendixes

Appendix A – Value Engineering Material

Appendix B – Site Layouts

Appendix C – Evaluation Criteria and Supporting Documentation

Appendix D – BAF Vendor Proposals

Appendix E – Example Process Flow Diagram

Appendix F – Detailed Cost Information

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1. Introduction 1.1 Background The City of Brockville (City) currently operates a wastewater treatment plant with primary treatment and sodium hypochlorite disinfection – the Brockville Water Pollution Control Centre (WPCC). Sludge is treated using anaerobic digesters which generate methane used for in-plant heating. The MOE issued an order to the City to complete an environmental assessment (EA) for the upgrade of the plant to secondary treatment, which provides the current minimum level of treatment required in the Province of Ontario. In order to reach this goal, the City has been awarded grant funding to assist in completing a secondary treatment expansion. This grant funding is part of larger funding initiative by the Strategic Infrastructure Fund, administered by Industry Canada, to improve water quality in the St. Lawrence River/Great Lakes area.

The City has previously completed a number of steps to move toward its upgrade goal including completion of the Environmental Assessment (EA) in January 2005, as required by the MOE order, and by participating in a working group of local municipalities to study the feasibility of including a local septage receiving and treatment facility as part of the future Brockville WPCC upgrade. The City recently completed a cogeneration feasibility study to assess the potential for inclusion of cogeneration in the plant expansion. The study concluded that cogeneration was not financially viable at this time. Also, the septage receiving facility is currently not being included in the plan for the secondary expansion.

The following provides a summary of work completed to date with respect to the upgrade of the plant, or that may provide relevant background data:

Assimilative Capacity Report, May 2004

EA report, January 2005

The City was successful with its funding request to the Canada Strategic Infrastructure Fund in the amount of $30.6M, representing two-thirds of the project funding, with the remaining funds to be provided by the City. One of the Requirements of the funding assistance is that the project be completed by March 31, 2012.

Project Chartering Session November 26, 2007

Technical Memorandum #1 –Evaluation Criteria for Selection of Secondary and Disinfection Technologies, December 2007

Technical Memorandum #2 – Preliminary Screening of Secondary Treatment Technologies, December 2007

Technical Memorandum #3 – Design Basis, December 2007

The EA report reviewed several areas, and included the following key items:

Secondary Treatment – further evaluate three final technologies including conventional activated sludge (CAS), biological aerated filters (BAF), and moving bed bioreactors (MBBR). These technologies were chosen based on preliminary evaluation from a longer list of available secondary treatment technologies. This study further evaluates the three technologies and recommends one for implementation.

Disinfection – further evaluate ultraviolet (UV) disinfection and chlorination/de-chlorination (chlor/dechlor). This study further evaluates the two options and recommends one for implementation.

Sludge Treatment Needs – an additional digester was not indicated as a firm requirement in the EA, however, the EA indicated that this required further review, and that an additional digester is desirable based on redundancy for maintenance/shutdown periods for the existing two digesters. A new solids handling process has been proposed in this report involving thickening of waste activated sludge prior to the digesters, so that the existing digester capacity is sufficient without the requirement to construct additional digestion facilities at this time.

Septage Receiving – the EA considered various scenarios where a Regional septage receiving facility would be constructed at the WPCC. This option has since been eliminated and will not be included in this study.

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The team of CH2M HILL and JL Richards and Associates (JLR) was selected to complete a project to carry forward the recommendations and outcomes of the EA report, and arrive at a final recommendation for the scope of work and selection of treatment technologies, including estimated costs, for the upgraded Brockville WPCC.

1.2 Project Objectives The key objectives of this study are as follows:

To evaluate the options presented in the EA and decide upon the secondary treatment and disinfection processes based on life cycle cost, operability, and suitability for the long term needs of the WPCC.

To develop a Class C/D cost estimate associated with the proposed secondary treatment and disinfection system upgrades that will allow the City to evaluate budgetary constraints for other possible work required as part of the secondary upgrade at the plant.

Class C/D estimates are defined by Public Works Canada and are further described in Section 14.0. A Class C estimate is prepared with limited site information and is based on probable conditions affecting the project. It represents the summation of all identifiable project component costs. It is used for program planning, to establish a more specific definition of client needs and to obtain approval-in-principle. A Class D estimate is a preliminary estimate, which due to little or no site information indicates the approximate magnitude of cost of the proposed project, based on the client’s broad requirements. This overall cost estimate may be derived from lump sum or unit costs as identified in the construction cost manual for a similar project. It may be used to obtain approval-in-principle and for discussion purposes.

1.3 Project Scope The project scope at the EA level included a high level review of available treatment technologies, disinfection technologies, and a review of impacts of secondary treatment on existing sludge treatment and solids handling needs. These items have been reviewed in more detail during this study at a conceptual design level.

The following items are included in the project scope of work for the upgrade to the Brockville WPCC. These items are necessary for the implementation of secondary treatment including integration with the existing facility.

New primary effluent channel from existing primary tanks to the new secondary treatment works

New secondary treatment works – conventional activated sludge

New secondary effluent channel from secondary treatment works to new disinfection facility

New disinfection facility - ultraviolet including new duty/standby channels and UV lamp banks, controls, and cleaning systems

New waste sludge piping from secondary treatment to a new waste activate sludge (WAS) holding tank and thickening facility

New centrate equalization tank/pump station to store centrate from dewatering and re-introduce to the plant during low loading periods

Ancillary systems to secondary treatment including return activated sludge (RAS) pumping, waste activated sludge (WAS) pumping, and scum removal

New WAS thickening facility to thicken WAS prior to digestion

One new digested sludge holding tank for centrifuge feed in winter and feed to offsite sludge hauling in summer

Upgraded digester mixing including external draft tube mixers

New facilities including control room, and electrical room to house the equipment associated with the new treatment facilities, but not intended to replace the existing administration or control facilities

New tunnels to connect the operating gallery from secondary treatment to the existing underground tunnel system

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New emergency standby power, new site electrical feed upgrade to 44 kV

Instrumentation and controls to integrate the secondary treatment system into the existing plant control system, and any upgrades required for this integration

The following items are considered outside the scope of this project:

Off-site collection and wastewater pumping including upgrades to the Main Pumping Station

Conveyance of flows in excess of 54,500 m3/day, the current maximum rated pumping capacity of the Main Pumping Station and the existing primary plant

Regional septage receiving facility, septage only from 280 homes within the City limits to be received at the facility (see Design Basis section for further information)

Cogeneration not included, a cogeneration feasibility study concluded that cogeneration was not recommended for implementation at the Brockville WPCC due to the small scale of the project and projected financial and operations implications in the long term. This could be reviewed during preliminary design, in conjunction with considerations such as possible needed boiler replacements, waste gas flare upgrades, and standby power for the recommended secondary treatment plant upgrade.

Replacement of the existing remote facility/paging system as part of the instrumentation and control upgrade

A number of items have been identified by the City as operational and/or maintenance issues, that would be desirable for upgrade or rehabilitation. A list of these items is provided in Table 1-1. These items will be reviewed in the context of project budget, considering any available funds following the implementation of secondary treatment. These items are discussed further in Section 6.0. A category has been assigned to each item based on the descriptions below. The items in Table 1-1 have been listed in order of importance as identified by City operations staff.

Category #1 – Required for secondary upgrade – i.e. a process upgrade to the existing process will be required for proper plant functionality, and therefore this cost must be included in the secondary upgrade capital estimate. An example might be upgrades to digestion or solids handling based on increased sludge volumes from the secondary treatment process.

Category #2 – Desired for secondary upgrade – the change or renovation of a particular item in the existing plant that would be beneficial to the secondary upgrade in terms of ease of operation, but not absolutely necessary. Examples might be grit removal improvements.

Category #3 – Maintenance upgrade – an item that would improve operational efficiency at the plant however is not essential for the secondary upgrade. This type of item would be included should sufficient budget allow for this after completion of the secondary and disinfection upgrades, and other priority items. An example might be modifications or improvement to the primary clarifier weirs. This type of item could be included in the design/tender as a “provisional item” and included in the project if tender pricing is favourable.

A number of these items will be addressed as part of the recommended secondary treatment project as ancillary upgrades to the existing facilities that would be integrated with secondary treatment design, particularly with respect to solids handling and digestion. Section 6.0 describes the items in Table 1-1 briefly and how they may be addressed during detailed design.



TABLE 1-1 List of Items Requiring Upgrade or Rehabilitation at the Brockville WPCC

Item No. – In Order of

Importance to the City

Description Category

1 Dewatering - Dewatered Centrate must flow away from Centrifuges quickly and to an appropriate location within the WPCC

1

2 Digester Operations - Must have complete mixing of each Digester. 1

3 Dewatering - Feed Sludge must have proper blending in order to give consistent feed sludge concentration to the Dewatering Centrifuge

2

4 Grit Removal - Must have better grit capture; grit is not fully being removed and/or causing premature wear on equipment and Digesters

2

5 Screening - Problems with Screening Equipment and retained water, odours (H2S is a H & S concern); 3/8" screen retrofit maintenance concerns; access area to work on Screens is a H & S concern

2

6 Primary Tanks – Concrete: Condition of existing tanks, dead spots and access areas in the tanks

3

7 Boilers - Must have replacement of Boilers 501 and 502; 502 is soon to be red tagged o/s (safety issue)

3

8 Primary Tanks - Mechanical Gears and Shaft Condition Assessment 3

9 Controls - ALL PLC's require upgrade to RSLogics (current programming language)

2

10 Primary Tanks - Effluent Gates installed to eliminate flow from weir boxes for Maintenance work

3

11 Primary Tanks – Investigate adjustment of effluent weir to achieve better hydraulic splitting at average day flows

3

1.4 Value Engineering A Value Engineering (VE) workshop was held in Brockville on January 22 and 23, 2008. The objectives of this workshop were:

To review the present findings based on the completed conceptual design

To review specific aspects of the project from a QA/QC perspective through use of focused teams looking at areas such as site optimization, secondary/disinfection treatment process, etc.

To look at major project components for creative alternatives and ideas to add value to the project (Note that “adding value” does not necessarily imply reduced costs, but alternative approaches that may better meet the City’s goals and/or implementation of the project)

The VE workshop was held over two days, and was attended by a diverse group of people to provide different perspectives on the project. A meeting agenda including the list of attendees is included in Appendix A. During the brainstorming session of the VE workshop, attendees were broken out into groups to address different project components as outlined in Table 1-2.



TABLE 1-2 Value Engineering Brainstorming Teams

Team Name Team Members

Site Optimization Greg Ashley Ed Malcolmson Jill Buckland Dave McDonald Umar Alfaruq

Secondary Process Brian Hein Dan Lalande

Biosolids Hugh Tracy Melodie Hobbs Tim Constantine Chris Cassidy

Existing Facilities Clare Humphrey Barry Fox Scott Marshall Michael Paul

Project Delivery Conal Cosgrove Lucas Smith Peter Raabe

The outcome of the VE session included a number of proposals that were made by each team, as listed in Table 1-3. The proposals were presented by each team to the entire VE group, and the recommended action as to whether or not to include the proposal in the final design was determined based on the presented arguments for each proposal. A detailed description of each proposal, including conceptual cost estimates (either increase or decrease to the overall project cost) and included in the VE material, Appendix A.

The decided upon actions for each proposal are outlined in Table 1-3. Those actions that were recommended to be carried forward have been incorporated into this final Conceptual Design Report. There are a number of proposals that should be considered further during preliminary/detailed design, as noted in Table 1-3.



TABLE 1-3 Value Engineering Proposals and Recommended Action

Proposal Number Description Team Action

1 Cake Storage (Winter) Biosolids Not to be carried forward

2 Do not add 3rd digester Biosolids Carry forward

3 Separate WAS thickening Biosolids Include this item with Proposal #2 to be carried forward

4 New Chemical facilities (coagulation) Site Optimization To be evaluated during preliminary/detailed design

5 Add Intermediate pumping Site Optimization Not to be carried forward

6 Minimum requirements for Standby Power Secondary Process Carry forward to preliminary

design

7 Utilize excess primary treatment capacity for another use Existing Facilities Not to be carried forward

8 Primary Sludge Degritting Existing Facilities Not to be carried forward

9 Move site closer to river Site Optimization Not to be carried forward

10A Optimize scum removal process from primary (only if BAF selected as secondary treatment technology)

Secondary Process Not to be carried forward, BAF not selected

10B Optimize scum removal process to avoid digester (only if BAF selected as secondary treatment technology)

Secondary Process Not to be carried forward, BAF not selected

11 Upgrade existing gas handling Existing Facilities

Category #3 item – to be considered as part of possible plant rehabilitation/upgrade if sufficient funds exist – not included in Conceptual design for new secondary/disinfection facilities – evaluate during preliminary design

12 New chlor/dechlor with new chem facility Secondary Process

Not being carried forward - UV is the selected disinfection technology

13 Circular clarifiers Site Optimization Not to be carried forward

14 Program Delivery Program Delivery To be evaluated during preliminary/detailed design

15 Excavation optimization Site Optimization To be evaluated during preliminary/detailed design



2. Existing Plant 2.1 Problem Statement The existing Brockville WPCC plant does not meet the level of normal treatment, which is secondary treatment or equivalent as stipulated in the Ministry of Environment (MOE) Guideline F-5 and Procedure F-5-1. Additionally, the WPCC currently exceeds the existing Certificate of Approval (CofA) limits for biological oxygen demand from time to time. The Ministry of Environment issued a Provincial Officer Order, which required the City to assess alternative solutions to address this issue and to include a statement that the plant also does not meet the minimum treatment standard of primary treatment. This order was addressed through completion of the EA.

2.2 Treatment Processes The existing Brockville WPCC is a primary plant. Unit treatment processes include duty/standby mechanical screens, aerated grit removal channels, chemically assisted primary clarification and disinfection using chlorination. Anaerobic digestion of primary sludge is carried out, followed by sludge thickening with centrifuges for off-site use and/or disposal. Disinfection at the existing plant is achieved by means of chlorination with sodium hypochlorite, using a concrete contact chamber.

The existing outfall consists of a 900 mm (36”) diameter concrete pressure pipe running into the St. Lawrence River and terminating with a diffuser system. The outfall has been inspected on the exterior within the last five years, and was found to be in good condition, with minor repairs required to the diffusers. An internal inspection was not completed.

The figures in Appendix B include the layout of the existing plant.

2.3 Flow Rates The existing plant is rated to treat an average day flow of 21,800 m3/day, with a peak rate flow capacity of 54,500 m3/day. These flows are as outlined in the EA and the CofA. A majority of flows are conveyed to the WPCC through one influent sewer from the Main Pumping Station, which is in turn fed from several smaller stations and gravity sewers. A gravity sewer connected to the main influent sewer on the WPCC grounds conveys a small amount of wastewater from the east of the plant.

Bypassing does not currently take place at the plant, but rather at the Main Pumping Station. By-passes at that facility are infrequent, for example, no by-passes were recorded in 2007, and two by-pass events were recorded in 2006. Long wet weather flow periods can be experienced at the WPCC based on the inflow to the Main Pumping Station. Consideration of wet weather flow periods up to 48 hours was included in the conceptual process design.

Currently measurement of influent flows to the plant is carried out by a Doppler meter at the head of the plant and effluent flows are measured using a Parshall flume in the primary clarifier effluent channel, prior to disinfection. Confirmation of flows to the plant to quantify accuracy of existing flow metering has not been carried out prior to completion of this study and is recommended to be completed during preliminary design.

2.4 Certificate of Approval The original existing certificate of approval (C of A) for the Brockville WPCC was not available at the time of

this study. However, amendments to the original certificate were issued as:

“Sewage Works Approval” in 1978 by the Ontario Ministry of the Environment, for expansion of the original facility including addition of two new primary clarifiers, extension of the chlorine contact tank, secondary digester, screening and grit facilities, and associated facilities.

Amended CofA #3-1974-88-917 in November 1991, for addition of the centrifuge dewatering facility, and upgrades to the existing digester facilities.

Amended CofA #3-1974-88-917 in August 1994, for addition of two mechanical screens, and aerated grit removal, and installation of new inlet sewer to the tank (including abandonment of three previous smaller inlet sewers).



3. Design Basis 3.1 Wastewater Flow and Characteristics Table 3-1 presents flow data from 2003 to 2006 for the Brockville WPCC. Also included in this table are the existing plant capacity, as well as future and projected flows, and population.

The flows noted in Table 3-3 are a summary of the design criteria that were used for this study. The design basis for flows considered during process design of the secondary treatment process also included a maximum month flow and a conservative approach to redundancy when considering average daily flow and average annual flow.

TABLE 3-1 Current and Projected Future Flows

Average Day Flow (m3/d)

Maximum Daily Peak Flow (m3/d)

Population

Existing Plant Capacity (1) 21,800 54,500

2003 (1) 17,800 40,180

2004 (2) 19,700 39,900 21,475

2005 (3) 21,000 48,400

2006 (Jan to Sept) (3) 19,500 43,900

2004-2006 Average 20,000 48,400

Future Period (2014) (1) 18,660 46,625 22,573

Future Period (2029) (1) 20,050 50,125 24,295

Design Period (2027 – 20 years) 21,800 54,500

Notes: (1) Class Environmental Assessment Report (January 2005) – rated capacity of the existing plant (2) 2004 Annual Summary Report (March 2005) (3) WaterTrax Data for 2005 and 2006



Table 3-2 presents the influent loadings from 2001 to 2006 as obtained from various data sources. There was no septage receiving during this period.

TABLE 3-2 Historical Influent Loadings

BOD5 (mg/L) TSS (mg/L) TP (mg/L) TKN (mg/L)

2001-2003 (Average) 1 112 143 3 12.4

2004 2 91 142 2.7 Note 4

2005 3 90 118 2.5 Note 4

2006 (Jan to Sept) 3 86 127 2.8 Note 4

2004-2006 Average 89 129 2.7 Note 4

Notes: (1) Class Environmental Assessment Report (December 2004) (2) 2004 Annual Summary Report (March 2005) (3) WaterTrax Data for 2005 and 2006 (4) TKN Data currently not available through WaterTrax database in the raw influent The City of Brockville receives wastewater from a number of industrial facilities, which contribute to the influent wastewater characteristics.

One particular facility has in the past caused elevated pH as high as 11 at the wastewater plant for up to one hour. The City has indicated that pH spikes in the wastewater influent will be controlled through sewer use by-law enforcement. Such enforcement is recommended to preclude the discharge of any substances that can have a deleterious affect on the WPCC. It is impractical to design systems for the plant to detect and pre-treat discharges that could upset the plant. This includes discharges of alkaline materials to the extent that they could cause a significant plant impact.

High pH discharges are not uncommon in municipalities with industrial dischargers, particularly food processing. These facilities employ both caustic and acidic type cleansers; however, their discharge tends to be predominantly basic. For this reason, some facilities employ on-site pH adjustment systems which control the pH of the discharge within by-law limits, typically between 6 and 9 or 10. Despite these controls, there are times when the effluent can exceed the by-law, measured at the facilities point of discharge. Such incidents, in CH2M HILL’s experience, have generally not been reported to impact plant operations.

Some level of excursions in pH can typically be tolerated by wastewater treatment plants owing to their inherent buffering capacity. Systems that are installed that affect pH are related to maintaining sufficient alkalinity. In these cases a basic substance such as soda ash is added to avoid pH depression which can adversely affect treatment performance. However, total system hydraulic retention times in the range of 12 hours will tend to mitigate adverse affects. Based on the hydraulic retention time and inherent buffering capacity, municipal treatment plants rarely, if at all, pre-treat for pH control and it is not anticipated that this would be required at the Brockville WPCC.

Using a conservative design approach, the influent loadings from the EA and flow data as determined with the City will be used as the basis for this project. These values are provided in Table 3-3 with rationale as to their selection as a design basis.



TABLE 3-3 Design Basis Influent Loadings and Flows To Be Used for Secondary Treatment Conceptual Design

Parameter Raw Wastewater

Rationale for Use as Design Basis

Flow 21.8 MLD -Average Day

54.5 MLD - Peak

The average day and peak flows are based on the existing plant rating and the EA.

BOD ( mg/L) 120 From Tech Memo #4 in the EA. It represents a similar (low) strength waste to the numbers provided in Table 1 based on recent plant data, in that the average BOD (from 2001 to 2006) in that memo was 100 (if you average the 2001-2003 Average, and the 2004-2006 Average).

TSS (mg/L) 160 From Tech Memo #4 in the EA. It represents a similar (low) strength waste to the numbers provided in Table 1 based on recent plant data, in that the average TSS (from 2001 to 2006) in that memo was 136 (if you average the 2001-2003 Average, and the 2004-2006 Average).

TP (mg/L) 4 From Tech Memo #4 in the EA. It represents a similar (low) strength waste to the numbers provided in Table 1 based on recent plant data, in that the average TP (from 2001 to 2006) in that memo was 2.85 (if you average the 2001-2003 Average, and the 2004-2006 Average).

TKN (mg/L) 25 From Tech Memo #4 in the EA. It represents a similar (low) strength waste to the numbers provided in Table 1 based on recent plant data, in that the average TKN (from 2001 to 2006) in that memo was 12.4 (if you average the 2001-2003 Average, and the 2004-2006 Average).

3.2 Septage Receiving Only a relatively small contribution of septage from properties located within City limits is expected for the upgraded plant. The number of homes is as shown in Table 3-4.

The inclusion of septage will have very little impact on average influent loadings, due to the relatively small proportion of homes with septic tanks to the overall population of Brockville. This is based on the assumption of 280 homes representing approximately 840 people at an average of three people per household, relative to a projected population of 24,295 in 2029. This 840 people is 3.45% of the total population of 24,295.

A location to allow haulers to unload septage into the system will be located onsite at the WPCC.

TABLE 3-4 Septage Quantities

Number

Residential 280 homes

Commercial None

3.3 Effluent Criteria The effluent criteria for this study are as determined by the assimilative capacity study completed in May 2004 and the EA completed in January 2005 and are listed in Table 3-5. These criteria are identical to those found in the EA, with the exception of the total ammonia, for which the suggested criteria in the assimilative capacity study were more conservative. The lower values for this parameter were utilized as a basis of design for this study in order to



ensure conservatism at this preliminary stage of review, as agreed to by the City at a progress meeting of December 20, 2007. Further, it should be noted that many existing plants applying for amended or new Certificates of Approval from the Ministry of Environment (MOE) are being required to have “non-lethal” effluent, which may remove the numerical limits for ammonia, and require that the Brockville WPCC meet the non-lethality requirements instead. This will be determined during the detailed design stage of the project through discussions with the MOE at the onset of the approvals process.

TABLE 3-5 Recommended Effluent Criteria – Monthly Average1

Parameter Criteria (mg/L) Design Objective (mg/L)

cBOD5 25 15

TSS 25 15

Total Phosphorus 1.0 0.8

Total Ammonia (as N) – Winter (December to May)

4 3

Total Ammonia (as N) – Summer (June to November)

2 1.5

E.coli 200 / 100 mL 100 / 100 mL

Notes:

(1) From “Brockville Water Pollution Control Plant Assimilative Capacity Analysis” by XCG Consultants, May 2004 and the Class Environmental Assessment Report by Simcoe Engineering and Hydromantis Consulting Engineers, January 2005.

3.4 Receiving Water The Brockville WPCC discharges effluent to the St. Lawrence River. A technical memorandum entitled Brockville Water Pollution Control Centre, Assimilative Capacity Analysis, May 12, 2004 was completed to evaluate the potential impacts that the upgraded discharge from the Brockville WPCC could have on the receiving water and to determine appropriate effluent criteria. The reader is referred to this document for further information, which provides the basis along with the EA for the effluent criteria as discussed previously in Section 3.3.



4. Secondary Treatment and Disinfection Technology Review 4.1 Approach to Evaluation Evaluation of the technologies to be selected for implementation at the Brockville WPCC for secondary treatment and disinfection has followed a decision making process as follows:

Environmental Assessment (EA) – a long list of secondary treatment and disinfection technologies were reviewed, including:

Secondary Treatment Conventional activated sludge

Trickling filters/solids contactor

Rotating biological contactor

Sequencing batch reactor

Biological aerated filter

Biological nutrient removal

Membrane bioreactors

Moving bed biofilm reactors

Disinfection Chlorination/dechlorination

Ozonation

Chlorine dioxide

Bromine chloride

Ultraviolet radiation

Environmental Assessment – a short list of technologies was recommended for further review during design. The reader is referred to the EA report for further background information on the long list of technologies, including the recommendation for short listing of the following:

Secondary Treatment Conventional activated sludge

Biological aerated filter

Moving bed biofilm reactors

Disinfection Chlorination/dechlorination

Ultraviolet radiation

Conceptual Design – a preliminary screening of the short listed alternatives for secondary treatment was completed. Two final technologies were recommended to move forward to conceptual design for secondary treatment – conventional activated sludge and biological aerated filters. The disinfection short list remained the same as the EA recommendation. The moving bed biofilm reactor (MBBR) was removed from consideration during conceptual design based on a preliminary screening with respect to implementation, operations and technical considerations. The final scoring for the MBBR indicated that even with inclusion of life cycle costing, this alternative would not reach the threshold for consideration as the recommended technology. The evaluation criteria used throughout this study are outlined in Technical Memorandum #1, Appendix C. The



preliminary screening and results are as outlined in Technical Memorandum #2, Appendix C, with backup materials included in Appendix C including the preliminary evaluation scoring.

Conceptual Design – a final evaluation of the short listed technologies for both secondary treatment and disinfection was completed. The evaluation was conducted using the criteria as outlined in Technical Memorandum #1, to arrive at final scoring for each alternative, and a scored ranking. This ranking was the ultimate basis upon which the recommended final treatment technologies were selected. Appendix C contains the final supporting documentation including the evaluation criteria, and scoring. Section 4.3 provides further information of the rankings and recommendations.

4.2 Conceptual Design Conceptual design for each technology was completed prior to the evaluation of short listed technologies, in order to provide a basis for scoring for each evaluation criteria. This report provides a summary of the work completed during this conceptual design.

As part of this design, site layouts were developed to illustrate possible plant footprints for the various technologies (i.e. conventional versus BAF), potential construction staging, and future expansion areas for the secondary treatment and disinfection alternatives. These figures are included in Appendix B. Figures 1 through 3 represent the initial proposed site layouts for consideration during the VE workshop. The final recommended site plan is included as Figure 4 at the end of this report, following Section 15.0 – Conclusions and Recommendations.

4.3 Secondary Treatment The following treatment alternatives were reviewed during conceptual design:

Conventional activated sludge (CAS)

Biological aerated filters (BAF)

4.3.1 Design Basis 4.3.1.1 Conventional Activated Sludge Table 4-1 presents a summary of the CAS design basis for this study. Conventional activated sludge for secondary treatment generally consists of an aeration and secondary settling tank system (final clarifiers). The aeration tanks provide an environment for biomass to grow which in turn remove pollutants in the wastewater through their biological processes. The biomass is easier to settle out of the wastewater as it increases in size through digestion of the pollutants, and is removed in the final clarifiers. A portion of the solids removed is recycled to the aeration tanks to maintain a healthy biomass population, and a further portion is wasted daily and further processed through digestion and solids handling facilities for disposal.

A process flow diagram for CAS process is included at the end of this report, following Section 15.0 – Conclusions and Recommendations.



TABLE 4-1 Key Design Parameters for Process Sizing – Conventional Activated Sludge (CAS)

Treatment Unit Design Basis

Screening − Existing process sizing sufficient for design flows

Grit Removal − Existing process sizing sufficient for design flows

Primary Clarification − Existing process sizing sufficient for design flows, and possibly up to 40,000 – 45,000 m3/day based on an average SOR of 40 m/d

Aeration

− HRT = 7.2 hours @ Average Daily Flow

− SRT = 10 days

− MLSS = 2,900 mg/ L

− Total volume = 6,600 m3 (3 tanks @ 2,200 m3)

− Conceptual Design based on water depth of 5.5 m

Final Clarification

− Sizing = 12 m/d @ Average Day Flow

− Based on Surface Overflow Rate (SOR) at max day flow = 26 m/d

− Total surface area = 1800 m2 (3 tanks @ 600 m2 each)

− Dimensions based on water depth of 5.0 m

Disinfection

− Sized to treat up to 54,500 m3/d hydraulically and up to a maximum month flow of 25,000 m3/d with a UV Transmittance (UVT) = 60% for secondary plant effluent

− Peak flows will receive disinfection at a lower level, however, the system is designed to meet the regulatory requirement of 200 E. coli/100 mL as a monthly geometric mean

Digestion − Anaerobic digester volume sized to achieve SRT > 15 days at peak month

solids loading

4.3.1.2 BAF Two vendors were consulted during conceptual design for the BAF process: John Meunier (Biostyr®) and Degremont Technologies (Biofor®). These vendors are the two main suppliers of this technology, representing all of the installations in Canada to date. The following provides a brief background on the BAF process from each of the two vendors, as each process is slightly different due to the proprietary nature of the systems. The process descriptions are taken directly from text provided by the vendors with minor modifications. The vendor proposals and information are included in Appendix D.

Biofor The Biofor® filter is a Submerged Biological Aerated Filter (SBAF) designed to treat primary effluent for removal of carbonaceous and nitrification oxygen demand, and total suspended solids from the waste stream (Biofor® C and N). Because of the modular design concept, the quantity of filters can be reduced or increased to accommodate the treatment capacity today (flow and load) and in the future.




Aerated biological filtration combines in a single step both biological degradation of biodegradable soluble matter and solids retention by mechanical filtration of suspended solids. Clarifiers downstream are not needed.

Biological filtration is achieved in up-flow filters loaded with a suitably sized granular support media, thus providing an efficient filtration effect. The filter media provides adequate support for biomass attachment and a mechanical filtration capability.

Process air provides the necessary oxygen for aerobic biological activity and is introduced in the media through a network of diffusers (Oxazur) located at the base of the reactor. Oxygen transfer is achieved in the media due to the up-flow pattern of air bubbles. The biological filtration process is of the submerged bed type.

Co-current up-flows of air and water allow for the finest particles to accumulate towards the upper reaches of the support media thus avoiding system clogging; suspended matter becomes attached through the full height of the media which allows for long filter runs. The influent must be screened to avoid clogging of the filter nozzles.

During treatment biomass accumulates in the support bed because of the bacterial growth due to the elimination of dissolved pollution and the retention of suspended solids in the raw water, and of the biological flocs.

Periodic backwashing is necessary. The frequency varies from 24 hours to 48 hours depending on the loadings applied and the treatment objectives. The filter wash is of the co-current type and the techniques are similar to those applied to sand filters for potable water using simultaneous water and air. Treated water is used for running the wash sequences. The wash sequence is designed so that it causes no damage to the support medium yet retains the biomass required for rapid restart of the bio-filter after backwash. This ensures that the biofilter can immediately return to service with the desired treatment efficiency.

Biostyr The Biostyr® process belongs to the family of biological aerated filters and can be designed to remove BOD and TSS, and provide nitrification, and/or denitrification. The filter media acts as a filter for the physical removal of suspended solids, while providing ample surface area for the attachment of a biofilm. The purpose of the biofilm is to achieve biological treatment of the soluble influent contaminants.

The influent wastewater is first brought to a common inlet feed channel above the Biostyr® cells where it flows down to the individual cells by gravity. Upon entering the Biostyr® cells, the wastewater flows upwards through the filter media. The media is composed of specially treated expanded polystyrene beads covered by active biomass. Ceiling plates with regularly spaced nozzles are used to retain the filter media in the cell. The nozzles allow the treated water to enter a common water reservoir above the filters, which in turn is used to provide water during backwash sequences.

Air Water Media

Scour Air Water to be

treated

Process Air (Oxygenation)

Biofor – Principle

Treated Water

Wash Water

Wash Water Outlet


A process air grid is located below the filter media so that the entire filter bed is aerated. BOD is oxidized by the biomass in the lower section of the filter. As the wastewater continues up the filter, additional BOD is consumed. When the BOD:TKN ratio falls below a certain limiting level, nitrification occurs, thereby reducing the ammonia level in the wastewater by converting it to nitrates.

Growth of biomass and the retention of suspended solids in the filter media make periodic backwashing necessary. The Biostyr® process is designed for a backwash interval of 24-72 hours (typically), depending on the application. The backwash phases are fully automatic and are triggered either when an operator adjustable time limit has expired or when the head loss across the filter exceeds a pre-determined setpoint. Water from the common treated water reservoir flows down through the filter by gravity, thereby fluidizing the media. The process air grid located below the media is also used to supply scouring air during the backwash sequence. The grids are regularly spaced pipe laterals with small orifices that produce a uniform, coarse-bubble pattern over the full cross-section of the filter.

Table 4-2 provides a summary of the BAF design basis, showing each item from the two vendors. The conceptual design for these proposals, including quantity estimation and costing, was based on the Biofor proposal, which did not include co-thickening, and which has a larger footprint, i.e. a more conservative design basis. Neither vendor provided proposals with one cell off-line at all times to allow for redundancy and conservatism in the design at the conceptual design stage. Therefore quantities and costs have been increased to allow for one additional cell (i.e. 9 cells as opposed to eight based on the Biofor design) to ensure direct comparison to the conventional activated sludge process from the redundancy perspective. The two vendor proposal costs for their proprietary system and equipment were very similar.




TABLE 4-2 Key Design Parameters for Process Sizing – Biological Aerated Filter (BAF)

Parameter Units Design condition

Biostyr

Design condition

Biofor

Number of cell off-line at all times - 0 0

Number of cell in backwash - 1 1

Total number of cells required2 - 5 8 (4 C/4 N)

Cell surface area m2 65 40

Total filtration surface m2 325 320

Media height m 3.5 3.9

Media size mm 3.6 2.7

Filtration rate ADF (including co-thickening flow)1 m/h 3.6 6.5

Filtration rate PHF (including co-thickening flow) 1 m/h 7.0 7.1

Filtration rate ADF (including co-thickening flow) @ N-11 m/h 4.5 8.6

Filtration rate PHF (including co-thickening flow) @ N-11 m/h 8.7 8.1

Aeration rate ADF, summer (average flow) m/h 5.7 5.7

Number of filters in backwash simultaneously - 1 1

Maximum Number of backwash per day per cell - 1 1

Design backwash rate m/h 60 20

30 (energetic wash)

Unit backwash water volume m3/cell 570 523

Daily backwash water volume m3/day 2850 2092 (Biofor C Cell once per day)

1046 (Biofor N Cell once per two days)

Total headloss through Biostyr process (approx) mm WC 3000 Not provided

(1) Biostyr includes co-thickening, Biofor design based on separate WAS thickening.

(2) Note that the vendor proposals did not include an off-line redundant cell for allowance during maintenance periods, etc. therefore one additional cell was considered during conceptual design to allow for redundancy as described in the report text preceding this table.

A process flow diagram for the BAF process is included in Appendix E.

4.3.2 Cost Analysis Life cycle costing was completed and included both capital and operations and maintenance (O&M) costs. Table 4-3 presents a summary of these costs, with further information and explanation provided in Section 14.0. The reader is requested to review Section 14.0 for details on assumptions and exclusions for these costs.


The capital costs of the two technologies are quite close, with CAS being slightly less. With respect to present worth on a life cycle basis, that is, the capital and O&M costs, CAS is lower than the BAF alternative. The O&M costs for BAF are higher than CAS, this is due to the greater number of pumps/blowers, etc. that are be included in a BAF process.

TABLE 4-3 Comparison of Secondary Treatment 20-Year Life Cycle Costs

Item CAS BAF

Capital Cost $11,400,000 $11,700,000

O&M Cost (20-year) $2,832,800 $3,250,600

Life Cycle Cost (20-year) $14,232,800 $14,950,600

4.3.3 Alternative Evaluation The CAS alternative requires a greater footprint than the BAF process, as can be seen from Figures 1, 2 and 3, Appendix B. As noted previously, further consideration of redundancy of BAF cells (right now each supplier has considered one cell out of service during backwashing for their peak filtration rate calculations) was considered and an additional cell was assumed to be required. At this time, we have conservatively chosen the larger of the two footprints provided by the vendors, that is, the Biofor footprint which included eight filtration cells of 40 m2 each, with the addition of the redundant cell.

The footprint of each technology has not only impact in terms of future expandability on site, but also impacts the construction layout and construction risk in terms of site access, and difficulty in construction. However, the BAF option with smaller footprint does limit the amount of construction that would be required to the south of the site, where increasing slopes toward the river may make construction more difficult.

It was assumed that the tanks will be constructed to allow for gravity flow for conventional activated sludge, therefore we have assumed preliminary underside of the tank elevations of 86.0 metres. For biological aerated filter during conceptual design, an assumed underside elevation of 82.5 was used as this construction is deeper than conventional activated sludge due to the multi-level tank design for the BAF facilities. The hydraulic headloss for secondary treatment and disinfection has been assumed to be 2.0 m for conventional activated sludge, and was used in determining the assumed conceptual underside of tank elevation. For biological aerated filter, the underside elevation was determined based on the vendor submission. Hydraulic gradeline through the BAF facilities is determined by the vendors based on their proprietary processes. Intermediate pumping has been assumed to be required for the BAF facilities, due to the higher headloss through the process (due to the media filtration) therefore a cost for intermediate pumping at the BAF facility has been included in our cost estimate for that technology.

With respect to process performance and ability for the treatment processes to meet future effluent requirements, such as a potential for nitrification, the CAS process is expected to be somewhat more easily adaptable, especially with respect to meeting more stringent effluent ammonia limits, if required. CAS is also more easily adaptable to denitrification and biological phosphorus removal, although it is questionable whether this would be required in the future. Meeting more stringent effluent ammonia limits with BAF may require either additional BAF trains or a two stage BAF configuration (i.e. organic removal stage followed by a nitrification stage). In the case of more stringent ammonia effluent requirements, it is possible that the performance guarantee for the BAF would be changed. Both processes are expected to be able to meet the effluent limits with respect to TSS, BOD, and TP without difficulty.

4.3.4 Recommendation The CAS alternative is recommended as the secondary treatment process for the upgraded plant based on the evaluation criteria and scoring developed with the City. The final score for CAS was a total of 8.2 out of a total possible 10 points, whereas the BAF alternative scored a total of 7.2 points. The CAS alternative also scored higher during the preliminary evaluation, and because the life cycle costs were not lower, the BAF technology did not move ahead in scoring over the CAS process.



4.4 Disinfection The reader is referred to the EA report for further background information on the technologies, including the recommendation to review these final technologies out of a long list of alternatives for disinfection at Brockville.

4.4.1 Design Basis The disinfection facilities are to be designed to disinfect the effluent of the Brockville WPCC to meet necessary bacteriological guidelines prior to discharge to the St. Lawrence River. The disinfection criterion at the plant is expected to be an E. coli concentration of 200 cfu/100 mL (monthly geometric mean), with a design objective of 100 cfu/100 mL. The disinfection process would be sized to disinfect the peak flow of 54,500 m3/d.

For chlorination/dechlorination it is assumed that the system is sized for disinfection of 200 cfu/100mL at maximum day flow, as stated in the design basis, Section 4.0. For this type of system, the combination of chlorine residual concentration and effective disinfectant contact time in a contact basin is used to quantify the capability of the disinfection system to provide effective pathogen inactivation, referred to as contact time or “CT”.

For UV disinfection the system is also sized on the basis of 200 cfu/100mL at maximum day flow. UV design takes into consideration the hydraulic design for the channels within which the UV reactors are installed, the UV dose and UV transmittance (UVT) of the lamps in order to determine the required number of lamps and power requirements to the lamps. The expected water quality of the secondary effluent at the Brockville WPCC has been assumed to be at 60% UVT and 15 mg/L suspended solids at this stage of design.

For UV at Brockville, two UV channels are proposed. These would each be sized hydraulically for the peak flow of 54,500 m3/d, thus one channel could pass peak flow with the other out of service, if necessary. Disinfection capability to meet the required effluent disinfection would also be included in both channels allowing for full duty/standby capacity, allowing for maintenance on one channel as required. The UV systems have the capability of providing lower power to the lamps using flow pacing, to allow for lower power use over the life of the system.

4.4.2 Alternative Evaluation The two disinfection alternatives have been evaluated based on technical requirements. Table 4-4 summarizes the evaluation.

TABLE 4-4 Disinfection System Alternative Evaluation

Parameter Chlorination/Dechlorination Ultra-Violet Disinfection

Safety to operators − Involves strong chemical handling and storage, risk to operators

− Minimal chemical handling involved, chemicals are used only occasionally for cleaning lamps

Environmental Impacts

− Possible formation of disinfection by-products − Risk of discharge of chlorinated effluent should

dechlorination system fail

− UV bulbs are returned to a recycler after replacement with new bulbs (service provided free of charge for by some vendors)

− Non-toxic effluent

Proven Technology − Most commonly used disinfection process for wastewater treatment

− Being operated in many small to medium-sized wastewater treatment plants with proven success

Performance − Capable of meeting disinfection requirements − More robust for disinfection of effluents with

varying quality, and for by-pass disinfection if required

− Capable of meeting disinfection requirements

Complexity − Simple process − Chlorination is currently practiced at the plant,

therefore operators are familiar with system

− Simple process − More operator training required




TABLE 4-4 Disinfection System Alternative Evaluation

Parameter Chlorination/Dechlorination Ultra-Violet Disinfection

Space Impacts − Larger footprint − Smaller footprint

O & M − Regular maintenance to chemical equipment − Chemicals would need to be delivered

regularly

− Cleaning of equipment as necessary

− Occasional manual cleaning of lamps may be required

− Lamp replacement − Requires greater standby power capacity

Reliability − Highly reliable − Readily adaptable for use in disinfection of

primary by-passes if desired in future

− Highly reliable

The requirements for UV design could require up to a 20% increase in UV dose, as BAF often requires a larger UV system to account for the larger possible particle size in the BAF effluent due to the sloughing of solids from the fixed film process. UV vendors are currently beginning to look into new BAF installations to ascertain the possible increase at this time. Chlorination/dechlorination systems are generally considered to be more robust in terms of overall process operation in variable effluent situations. Should future treatment by-passing be incorporated into the future plans for the Brockville WPCC, as opposed to the by-pass at the existing Main Pump Station, disinfecting primary effluent (the minimum level of treatment required for emergency by-passes) using UV should also be considered. The existing chlorine contact tank could be employed in this situation.

UV disinfection is often considered the more environmentally friendly disinfection technology from the perspective of formation of disinfection by-products and “non-toxic” effluent.

From a performance and complexity perspective, both systems are comparable, although the UV system would require some additional operations training and familiarization as chlorination is currently practiced at the plant and UV would be a new type of system.

4.4.3 Cost Analysis Life cycle costs, i.e. capital and O&M, over a 20-year period are outlined in Table 4-5. Operations and maintenance (O&M) costs are higher for the chlorination/dechlorination system due to the required chemical supply. The cost for sodium hypochlorite and sodium bisulphite delivery is approximately $97,000/year (a conservative value that assumes the design flow throughout the design period, which could ultimately be lower with lower flows in the early years of the 20 year life cycle period). This is significantly higher than the cost for cleaning and maintaining the UV system, which has been estimated at $54,000/year, which includes the cost of bulb replacement based on preliminary information provided by a supplier. The power consumption of the UV system is higher than that of the chlorination/dechlorination system, but that does not outweigh the cost of chemical delivery.

TABLE 4-5 Comparison of Disinfection System Costs

Item UV Chlorination/Dechlorination

Capital Cost $1,200,000 $700,000

O&M (20-year) $666,800 $1,298,800

Life Cycle Cost (20-year) $1,866,800 $1,998,800


4.4.4 Recommendation The recommended disinfection process for the Brockville WPCC is UV disinfection, based on the evaluation of the technology as included in Appendix C and described in the previous sections. The weighted scores for both alternatives were essentially equal, as they were 7.5 for both UV and chlorination/dechlorination. As the scores showed advantages to either process, the UV process was selected by the City based on operations staff input. The estimated overall life-cycle cost of the UV disinfection system is lower than that of chlorination/dechlorination. UV disinfection is proven and reliable and requires a smaller footprint than chlorination/dechlorination, while having minimal risk to the environment and operator health and safety.



5. Conceptual Design The following sections outline the unit treatment processes that will comprise the final treatment train at the Brockville WPCC. This section includes a review of each unit process, whether existing as part of the primary treatment plant, or part of the new secondary and disinfection treatment processes. Each section describes the evaluation of the unit process, and what the requirements are for the upgrade or expansion in order to implement the selected secondary treatment process.

Section 6.0 discusses the possible items that could be upgraded that are either Category #2 or Category #3, i.e. not required for secondary treatment or are maintenance items, based on the priority items identified by plant staff as described in Section 1.3. Category #1 items are included in the following sections, as they would be required for the secondary upgrade, such as the centrate equalization tank.

5.1 Treatment Processes and Process Sizing Process modeling was completed to determine process sizing, including required volume (aeration tanks) or surface area (clarifiers) for secondary treatment processes. Existing treatment processes were also reviewed to determine whether their current sizing will be sufficient to accommodate the inclusion of secondary treatment. Consideration was given to, among other things, the peak month raw wastewater loading, the redundancy requirements to allow for adequate treatment when one tank is taken out of service, as well as the flexibility to initiate chemically enhanced primary treatment and/or step feed. In all cases, the process design required that equalization of the dewatering centrate followed by night time return of this liquor to the liquid train to maintain effluent quality with respect to ammonia. A whole plant mass balance simulator was used to determine the process sizing, and thus includes items such as recycle streams (e.g. digester supernatant and centrate). Residuals from the City’s water treatment plant are sent to the WPCC, therefore, the data provided by the City and in the EA includes these solids.

The proposed treatment processes for the Brockville WPCC following the upgrade to secondary treatment and proposed design basis are outlined in Table 5-1.

TABLE 5-1 Treatment Processes and Design Parameters

Treatment Unit New/Existing Design Basis

Screening Existing Existing process sized based on peak flow up to 54,500 m3/d

Grit Removal Existing Existing process sized based on peak flow up to 54,500 m3/d

Primary Clarification

Existing Existing process sized based on 21,800 m3/d average day, peak flow up to 54,500 m3/d

Aeration New Sized to treat flow of 21,800 m3/d average day, and 54,500 m3/d peak instantaneous

Final Clarification New Sized to treat flow of 21,800 m3/d average day, and 54,500 m3/d peak instantaneous

Disinfection New UV Disinfection sized to treat flows up to 54,500 m3/d, duty/standby channels

Digestion Existing Existing digesters checked based on sludge production from existing primary process and new secondary process – new WAS thickening to be added to economize on digester capacity and allow for secondary sludge to be digested without additional digester construction

Dewatering Existing Existing process reviewed for flows up to 132 m3/day or 2640 kg/d at 2% dry solids (projected solids feed rate with secondary treatment)



Table 5-2 provides the key design parameters used for process sizing at the conceptual design level. Process design should be reviewed and refined at the preliminary design stage as required.

TABLE 5-2 Key Design Parameters for Process Sizing – Conventional Activated Sludge (CAS)

Treatment Unit Design Basis

Screening − Existing process sizing sufficient for design flow

Grit Removal − Existing process sizing sufficient for design flow

Primary Clarification − Existing process sizing sufficient for design flow, and possibly up to 40,000 –

45,000 m3/day based on an average SOR of 40 m/d without co-thickening (i.e. separate WAS thickening to occur)

Aeration

− HRT = 7.2 hours @ Average Daily Flow

− SRT = 10 days

− MLSS = 2,900 mg/ L

− Total volume = 6,600 m3 (3 tanks @ 2,200 m3)

− Conceptual Design based on water depth of 5.5 m

Final Clarification

− Sizing based on Surface Overflow Rate (SOR) = 12 m/d @ Average Day Flow, 26 m/d at max day flow

− Total surface area = 1800 m2 (3 tanks @ 600 m2 each)

− Dimensions based on water depth of 5.0 m

Disinfection − Two channels (duty/standby)each sized to treat up to 54,500 m3/d with an

assumed UV Transmittance (UVT) = 60% for secondary plant effluent

Digestion

− Anaerobic digester volume sized to achieve HRT > 15 days at peak month solids loading, existing digesters considered sufficient with separate WAS thickening to be added

Dewatering − Based on manufacturer’s requirements – centrifuges are existing and were

checked based on data in Table 5-1



Table 5-3 outlines proposed process equipment in terms of number of units, and basic unit sizing. Tank area and volume are rounded in some cases, such as the area of the clarifiers. The proposed sizing is based on conceptual level process modeling and calculations, and is approximately only. Final sizing for new processes and equipment should be reviewed during preliminary design.

TABLE 5-3 Summary of Process Tankage and Equipment Sizing

Treatment Unit Number of Units and Basic Sizing

SCREENING1

No. of Screens Existing - 2 (duty/standby mechanical)

No. of Screening Washer/Compactors Existing - 1

GRIT REMOVAL1

No. of Grit Tanks Existing - 2 (1 duty, 1 standby)

Volume of tanks (m3) total 103

Volume per tank (m3) 52

Dimensions per tank

Length (m)

Width (m)

Depth (m) – liquid

7.6

3.7

3.66

PRIMARY CLARIFICATION1

No. of tanks Existing - 4

Primary clarification area (m2) total 1160

Primary clarification area (m2) per tank 290

Dimensions (each tank)

Length (m)

Width (m)

Depth (m)

Approximate dimensions from existing drawings

29

8

4.0

AERATION

No. of Aeration Tanks 3

Total Aeration Tank volume (m3) 6,600

Volume per Aeration Tank (m3) 2,200


Length (m)

Width (m)

Depth (m)

27

15

5.5

Aeration Blowers 4 (3 duty, 1 standby), Variable Frequency Drives






Approximately 75 kW (100 HP)

Process Air (per tank) 2178 m3/hr, average daily flow

3267 m3/hr, peak flow

FINAL CLARIFICATION

No. of final tanks 3

Final clarification area (m2) total 1800

Final clarification area (m2) per tank 600


Length (m)

Width (m)

Depth (m)

40

15

5.0

Scum Pumps 3 (one duty per tank)

Approximately 1.5 kW (2 HP)

RETURN AND WASTE SLUDGE PUMPING

RAS Pumps 6 (1 duty, 1 standby per aeration/secondary tank)

RAS Pumping Rate 100% of Average Day Flow returned to aeration tanks

Approximately 11 kW (14 HP)

WAS Pumps 4 (1 duty per tank, 1 common standby)

WAS Pumping Rate Governed by minimum pipe size of 4” and velocity of 1 m/s – therefore pumping in the range of 650 m3/d – typically operated from 3-15 minute per hours

Approximately 3.7 kW (5 HP)

BIOSOLIDS TREATMENT

Type of Digester1 Existing - Anaerobic

No. of Digesters1 2 – Both operated as primary

Digester volume (m3) total1 2,180

Digester volume (m3) per tank1 1,060

WAS Holding Tank New - 120 m3

Digested Sludge Holding Tank New - 120 m3

SLUDGE DEWATERING

Type of Equipment1 Centrifuge

No. of Units1 Existing - 2 (Duty/standby)





Capacity (m3/d) per centrifuge1 5,103 kg/d at feed solids concentration of 2.7% (operated 5 days/week, 7 hours/day)

Centrate Holding Tank 100 m3

(1) – Information from previous studies, such as EA and EA background material.

The following sections briefly outline the design basis and assumptions for the unit processes in addition to the information provided in the previous tables, which will be further refined during preliminary and detailed design.

5.2 Inlet Sewer The main influent trunk sewer that conveys sewage to the existing WPCC consists of a 750 mm diameter pipe that flows into the existing screening facility. No changes are proposed to the influent sewer as part of the secondary treatment project.

5.3 Septage Receiving No special provision has been made for septage receiving at the upgraded plant for this study. Only 280 houses within the City limits will be permitted to utilize the WPCC for septage disposal, and therefore it is assumed that this septage will be offloaded using a simple septage receiving facility at the WPCC to be included as part of the preliminary design.

5.4 Screening The existing screening process has sufficient capacity to treat the peak flow of 54,500 m3/day which is the rated flow for the existing plant. No changes to the screens are required in order to implement secondary treatment using CAS.

5.5 Grit Removal The existing grit removal process has sufficient capacity to treat the peak flow of 54,500 m3/day which is the rated flow for the existing plant. No changes to the grit removal system are required in order to implement secondary treatment.

5.6 Plant Hydraulics The WPCC hydraulics will be governed by the elevation of the existing primary clarifiers, which have a weir elevation of approximately 92.8 m. As the St. Lawrence River is much lower than the treatment plant site, there is no concern with available hydraulic head on the outfall side of the plant within which to fit the secondary treatment system.

Items such as rock excavation and groundwater table should also be taken into account when considering a proposed hydraulic gradeline for the expanded plant, in order to assess where in elevation to place the new tanks. It is preferable from an operations perspective to avoid intermediate pumping of primary effluent, as this adds a pump station to the project, requiring ongoing operations and maintenance costs (i.e. pumping energy) and staff time. A VE proposal included review of this decision with respect to intermediate pumping, and it was not recommended to use intermediate pumping based on lack of benefit and operational issues such as increased long term O&M costs, site aesthetics, and risks during power failure.

For this study, the design basis is for gravity feed to the new secondary treatment plant from the existing primary clarifiers. This will likely involve considerable rock excavation, as knowledge of existing plant construction and previous geotechnical reports (e.g. in the area of the screening/grit facility) indicate bedrock close to the surface at the plant site. Therefore, we have assumed the most conservative estimate of excavation/rock removal by assuming


all excavation will be rock blasting. With respect to blasting versus hoe-ramming of rock, it was reported during previous construction of the dewatering facility that hoe-ramming was a slow construction method, and thus, we have assumed rock blasting will be necessary for the large amount of excavation required for secondary treatment construction at Brockville.

With respect to groundwater, we have assumed no significant groundwater elevation in the tank excavations at this stage of the study, again, based on previous knowledge during the screening/grit facility construction, where no groundwater flow into the excavation was encountered.

Both the rock elevation and groundwater elevation assumptions will need to be confirmed during preliminary design, upon completion of the geotechnical study.

A detailed hydraulic gradeline will be required during preliminary design, and confirmation of the decision with respect to required pumping to the new secondary plant determined at that time.

The disinfected effluent will be discharged to the river via a connection to the existing outfall downstream of the exit point from the existing chlorine contact chamber, which will be determined during the detailed hydraulic analysis.

5.7 Primary Treatment The existing primary treatment process at the Brockville WPCC consists of four rectangular primary clarifiers of approximately 32 feet wide and 98 feet long (9.8 m by 29.8 m). Each tank therefore has approximately 291 m2 of surface area, for a total of 1164 m2 for all four tanks. These tanks are sufficient to provide primary treatment at an average day flow of 21,800 m3/day and a peak flow of 54,500 m3/day. A review of the tank capacity indicates that these tanks may provide treatment up to 40,000-45,000 m3/day at the current loadings.

The original two tanks at the plant were built as part of the original plant construction in 1963, with an additional two tanks added in 1978. It is recommended that a condition assessment of the primary clarifiers be completed as part of preliminary design as deterioration of concrete in the tanks has been noted by operations staff.

5.8 Biological Treatment

5.8.1 Aeration System Supply of oxygen to the secondary treatment process is a critical component of a biological treatment system. Three aeration tanks, supplying oxygen to the biomass, will be constructed for the upgraded Brockville WPCC. The supply of oxygen is achieved through the use of blowers and diffusers that supply a uniform amount of air across the tank. The aeration tanks will have three passes, and will normally operate in plug flow mode, with aeration diffusers evenly distributed throughout the passes. The option will exist to operate in “step feed” mode, where influent to the aeration tanks can be distributed to the first pass, beginning and end of the second passes. The return activated sludge (RAS) is fed to the beginning of the aeration tank.

Fine bubble diffusers are proposed for the aeration tanks. The aeration tanks will require approximately 2178 m3/hr of air per tank at average flow conditions, and 3267 m3/hr during peak flow conditions, based on preliminary calculations. Air flow will be confirmed during preliminary design.

It has been assumed that four blowers will be supplied, one duty blower for each tank, and one common standby, each rated at approximately 75 kW (100 HP) and with variable frequency drives (VFD). Each blower will be capable of providing approximately 3300 m3/hr. The VFDs will allow for turndown of the blowers during normal aeration duty and for higher output as needed for process control. Further analysis during detailed design should be carried out to determine whether provision of inlet valve throttling would provide sufficient flexibility for blower turndown as compared to VFDs.

The blowers would be located in the basement gallery between the aeration and secondary clarifier tanks.

5.8.2 Secondary Clarification Three secondary clarifiers are proposed, each having a width of 15 m, a length of 40 m, and a side water depth of 5.0 m. The clarifiers are proposed to be of a “Folded Gould” design, which has been used successfully at many plants, and allows for the tanks to be designed in a more compact footprint, with greater length to width ratio than a standard clarifier. This type of tank was selected for the Brockville plant, based on site constraints requiring the



tanks to be as short as possible to fit within site space, and maintain access to the tanks and allow for expansion in the future. The Folded Gould design uses two passes in the clarifier.

The clarifier surface overflow rate at average day flow will be 12 m/d and 26 m/d at maximum day. This design allows for the flexibility to provide adequate clarification and thickening even for sustained peak flows (i.e. in excess of a day at the 54,500 m3/day peak) for sludge SVIs at or below 150 mL/g with all clarifiers and aeration tanks in service.

Sludge collection in the clarifier will take place using three sludge collection mechanisms, two running longitudinally in the tank, and one cross collector that runs across the width of the tank. The sludge collectors will be chain and flight type. The sludge collectors will pull sludge to a sludge hopper at the opposite end of the tank from the effluent launders, where piping will convey the sludge to the return and waste activated sludge pumps. Rake speed for sludge collection in the clarifiers would normally be within the range of 0.3-0.6 m/min.

5.8.3 RAS/WAS Pumping Pumping of sludge from the secondary clarifiers to the aeration tanks maintains active biomass in the aeration tanks. This is referred to as “return activated sludge” (RAS) pumping. In the upgraded Brockville WPCC, six RAS pumps are proposed, each sized at approximately 11 kW (14 HP). This arrangement will allow for one duty pump and one standby pump per tank. The RAS pumps will be located in the basement gallery between the new aeration and secondary clarifier tanks. RAS pumping has been sized for a flow rate of 100% of the average influent flow to the plant. It may be possible to consider reducing the number of standby pumps through common standbys, which should be further evaluated during preliminary design.

A portion of sludge from the secondary clarifiers will be wasted on a regular basis. The waste cycle can be automated for a certain time period or volume on a timed basis (for example, 10 minutes of every hour), or can be performed according to operator preference. This is referred to as “waste activated sludge” (WAS). In the upgraded Brockville WPCC, there are four proposed WAS pumps, each sized at approximately 3.7 kW (5 HP). WAS flow rates are based on the minimum discharge line size of 4” and a velocity of 1 m/s to accommodate pumping of solids, therefore, the pumps would have a flow rate in the range of 650 m3/day. Each tank will have a duty pump, with cross connection so that the standby pump can waste sludge from any clarifier should one duty pump be out of service. The WAS pumps will be located in the basement gallery between the new aeration and secondary clarifier tanks.

It is sometimes suggested that WAS pumps can be eliminated by allowing sludge wasting off of the RAS lines. This is not a recommended practice due to the significant difference in hydraulic head conditions between the RAS and WAS lines, and the requirement for pinch valves for control of flow. This has been practiced at other plants, with limited success, and the pinch valve often requires significant maintenance. Dedicated WAS pumps are recommended.

5.8.4 Scum Removal Scum will be collected from the secondary clarifiers using the clarifier’s chain and flight mechanisms, which collect sludge in the submerged portion of the tank, and scum with a blade mechanism at the top of the tank. Scum will be collected into one scum pit in each clarifier, where it will be pumped to the digester for further treatment.

Three scum pumps will be provided, one for each clarifier tank. The scum pumps will be located in the basement gallery between the aeration tanks and clarifiers. A size of 1.5 kW (2 HP) has been assumed for the scum pumps.

5.9 Disinfection Disinfection of treated wastewater will be achieved using UV disinfection. The UV system will consist of two channels which would be capable of providing full duty/standby UV treatment. Consideration should be given to optimizing this design during preliminary design, which could include reducing the UV requirements such that both channels would be required during peak flow from a UV treatment perspective, and only hydraulically size the channels for peak flow. With this design, at lower plant flows, all the flow through the plant would be disinfected through one UV channel. At higher flows, the inlet gate to the second channel would open and the flow would split evenly between the two channels. This will reduce the power costs of the UV system, and should be considered during preliminary design. However, in order to compare the UV and chlorination/dechlorination systems fairly and equally, full duty/standby systems have been included in this conceptual design and this provides a more conservative design approach at this stage.



Each channel would be hydraulically designed to convey the full plant peak flow of 54,500 m3/d. The MOE’s compliance limit and design objectives for disinfection are generally 200 E. coli/100 mL and 100 E. coli/100 mL respectively based on a monthly geometric mean. The UV unit were sized to provide the required disinfection based on UV transmittance of 60% and 15 mg/L suspended solids at the conceptual design level.

The proposed design involves one bank of UV lamps in each channel, each with nine modules containing eight lamps. Therefore, each channel will have 144 lamps in total. The power consumption of this system would be 36 kW per hour with all lamps operational on full power, during maximum flow. The UV system information should be confirmed during preliminary design. The information provided in this study is based on a preliminary quotation from one UV system vendor.

The proposed system will have automated mechanical/chemical cleaning, reducing the frequency at which the lamps would require removal for cleaning.

5.10 Outfall The existing outfall pipe consists of a 900 mm (36”) diameter concrete pressure pipe that was installed with the original WPCP. The outfall is a submerged discharge with eight 10” diameter diffuser outlets, and was originally installed with four diffusers open, and four blanked closed.

The exterior of the outfall has been inspected twice within the last 5 years, and showed that the current outfall condition is good, with minor repairs required to the diffusers. Outfall hydraulics should be confirmed during detailed design to determine if any additional diffusers require opening to account for increased flow over the years since original construction. It is recommended than an interior inspection of the outfall is conducted during preliminary design.

5.11 Sludge Digestion The Brockville WPCC currently operates two digesters in primary digestion mode. The digesters were constructed in 1963, and as such, a condition assessment of the existing tanks is recommended during preliminary design. These digesters will provide sufficient capacity for sludge digestion after the upgrade of the plant to secondary treatment with incorporation of separate WAS thickening and other improvements as outlined further in the following paragraphs. Digester capacity and requirement for new digesters should be reviewed during preliminary design and following the condition assessment.

This decision with respect to the existing sufficient digester capacity is sensitive to a number of items which were considered in making the recommendations for this study:

Minimum hydraulic retention time (HRT) = 15 days (per MOE). If lower HRTs occur, more rigorous testing would be required to demonstrate Class B biosolids production.

Requirements of the biosolids end use – what level of stabilization is required? – the City currently has a contract with an environmental contractor to remove biosolids for landfill at a private landfill during winter, and with a local farm for spreading of liquid biosolids in summer – further definition of required level of treatment of biosolids and anticipated future consideration must be determined. Currently no biosolids are landfilled within the City as the City landfill is closed.

Assumed primary and secondary sludge feed concentrations

Peak month volatile solids loading

Digestion redundancy requirements/contingency – i.e. what is done when a digester is out of service?

A number of design conditions were evaluated for digestion on a preliminary basis to determine the final recommended solution for digestion at the upgraded plant. This included an investigation of an aggressive design basis at an average day raw wastewater flow of 21,800 m3/day (using historical more dilute sewage characteristics, average annual raw sewage loadings, and thickening in the primary clarifier to 3.5% solids) as well as a standard (fairly conservative) design basis (Class EA stronger sewage characteristics, maximum month raw sewage loadings, and thickening in the primary clarifier to only 3.0% solids).



Using the more aggressive design basis with dilute sewage and thicker co-thickened solids from the primary clarifiers, at a flow of 21,800 m3/day, there may be sufficient digester capacity, as there would be approximately 11 days HRT when one tank is out of service. It would be difficult to justify that the existing digesters can meet a design flow basis with any average day flow greater than the existing rated plant capacity. Using the conservative and more typical design approach with the raw wastewater influent values from the EA, the existing two digesters would not be considered sufficient as 15 days HRT with both digesters in service would not be reached.

Co-thickening of the primary and secondary solids was not a desired process from the operations perspective at the Brockville WPCC based on VE outcomes. To address concerns with capacity and operations of the digesters, the following is recommended for implementation at the Brockville WPCC. This will address handling of biosolids while making use of the existing two digesters without the requirement to construct a new digester and associated facilities:

New separate WAS thickening (which may allow for an effective sludge feed concentration up to 5%, thereby increasing the overall digestion capacity) consisting of a WAS holding tank of approximately 120 m3, and a WAS thickening facility using drum thickeners and a polymer feed system. Thickened WAS would be pumped to the digesters for further treatment.

Upgrade of the existing digesters to include external draft tube mixing to improve mixing.

New digested sludge holding tank of approximately 120 m3 to store digested sludge for feed to the dewatering facility in winter, and directly to hauling for land application in summer. This tank could be included in a new facility to be constructed east of the existing dewatering building that would house WAS thickening, digested sludge holding, and centrate equalization facilities. This would combine all of these items into one common facility that would facilitate any odour control requirements and is near existing sludge dewatering and truck loading facilities.

New centrate holding tank/pumping station combined with the sludge holding tank as discussed further in Section 5.12.

5.12 Dewatering of Biosolids Dewatering of digested sludge is currently done using two centrifuges. The capacity of these centrifuges is expected to be sufficient to dewater the projected sludge volumes with the addition of secondary treatment. Confirmation with the centrifuge supplier with respect to the sludge feed dry solids is required to ensure that the existing centrifuges are sufficient with respect to dry solids feed concentration, and this should be confirmed during preliminary design.

It is recommended that a centrate holding tank and pumping system be constructed to store centrate liquid from the centrifuge dewatering process. This will allow controlled return of this material to the primary treatment process, thus equalizing the loading on the treatment plant during peak daytime hours. This centrate pumping station has been included in the costing for the secondary treatment upgrade as a Category #1 item.

5.13 Biosolids Management No change to the current biosolids disposal program is expected. Brockville currently dewaters sludge during the months of November through April and this material is removed by an environmental contractor for disposal at a private landfill. In the summer months, liquid biosolids are land applied through a partnership with a local contractor. The digested biosolids produced at the Brockville WPCC may be increased in quality through improvements recommended to the digestion process resulting in a more concentrated product. Currently biosolids produced at Brockville are considered Class B, and no provision has been made to produce a Class A product as part of the upgrade project.



6. Review of Existing Plant Upgrade/Rehabilitation Requirements As previously outlined in Section 1.3, Scope of Work, there are a number of items that are considered to be operations and maintenance issues at the existing plant. These items are addressed in the following sections, by process area, with recommendations for potential upgrade and/or rehabilitation should project funds be available following implementation of secondary treatment.

It is recommended that upgrade items identified as priorities by the City be included in the detailed design and tender process for the secondary treatment upgrade as provisional items, which could be selected for construction based on the final tender bids.

6.1 Screening Two existing mechanical screens with 3/8” opening size are located in the screening building. These screens were installed during a retrofit improvement during 2004/2005. Operations staff report consistent problems with maintenance of these screens, including misalignment of the bars/rake, causing rake tooth breakage, and difficulty in accessing the screens for maintenance.

Odour control has also been reported to be an issue, although an existing carbon odour control system is in operation.

A condition assessment and mechanical review of these screens is recommended to determine what improvement could be made concerning the rake alignment and maintenance issues. Replacement of the screens would not be recommended given their relatively recent replacement. Operation of the odour control system and regular maintenance procedures should also be reviewed, including a capacity analysis, to determine what improvements could be made.

6.2 Grit Removal Review of the existing grit tanks including removal of the scum removal system and opportunities for optimizing the aerated grit removal “tank roll” should be completed. The existing grit tanks reportedly do not efficiently remove grit, therefore carry over of the grit into the primary tanks and digestion/dewatering systems cause premature wear and increased maintenance requirements for equipment.

6.3 Primary Treatment Tank access to the existing primary clarifiers and concrete condition deterioration are reported problems from operations staff. To determine the extent of rehabilitation that may be required, a condition survey of the existing primary clarifiers is recommended during preliminary design. Additionally, some maintenance items such as mechanical gears and shafts on the clarifier drives, effluent gates and weirs require replacement or rehabilitation.

6.4 Digestion and Dewatering Improved blending of the digested sludge to the dewatering centrifuges and improved digester mixing are desired in order to improve efficiency of biosolids management at the plant. Ongoing issues with dewatering consistency and control are experienced.

This item will be addressed through the proposed changes to the existing plant that would be required as part of the secondary treatment upgrade, including addition of draft tube mixers to the existing digesters and a digested sludge holding tank for feed to the centrifuge. Further, the existing system does not convey centrate efficiently away from the dewatering centrifuges. This item will also be addressed through the addition of a centrate equalization tank and pumping system that is necessary as part of the secondary treatment upgrade to equalize centrate feed to the treatment process.

The above items that will improve existing digestion and dewatering are included in the cost estimate for the secondary treatment plant upgrade.



The following sections provide suggested concepts for the new secondary plant and disinfection facilities. The proposed concepts will require review at the preliminary design stage, when more detailed information is available regarding the selected process, actual equipment, geotechnical information, and further consultation with Hydro One. These sections are provided at the conceptual design stage in order to provide the City with the vision for the future plant at the time of completion of this report, and it should be understood that items are subject to change as the design process progresses.

7. Civil and Site Layout 7.1 General The secondary expansion is to be constructed on a portion of the site to the south-east of the existing plant. The orientation of the plant was recommended to be in the east/west direction based on the outcome of the VE workshop and review of the proposed site layout options shown in Figures 1, 2 and 3, Appendix E.

The recommended site layout is shown in Figure 4 following Section 15.0 – Conclusions and Recommendations. The sizes of the recommended facilities such as the new WAS thickening/digested sludge storage/centrate equalization facility, and UV disinfection facilities are based on typical equipment layouts from similar secondary treatment plant projects. Typical layouts for these types of facilities are included at the end of this report, following Section 15.0. These layouts are representative only, in order to show the type and number of pieces of equipment that are assumed will be included in the Brockville WPCC and were included in the cost estimates for conceptual design. The actual facility layouts will be developed more specifically during preliminary and detailed design. A typical pump/blower gallery layout for the Renfrew WPCP has also been included as a reference for typical piping/valving layout as a sample to the reader.

The topography of the site is sloped toward the river, with a steeper slope beginning south of the existing primary clarifier tanks. Site layouts have been proposed in consideration of the existing topography, which generally indicate that construction immediately south of the primary clarifiers would be difficult due to the steep slopes, limited access for construction and the existing outfall pipe below grade.

With respect to site access, it is recommended that a temporary access road for plant staff and deliveries/maintenance vehicles be constructed to the west of the site, as shown on the Figures in Appendix B. This road will separate daily operations traffic from construction traffic, and also allow for isolation of the construction site using fencing for plant security, also as shown on the proposed site layout figures. Gates at the entrance road to the construction site could be installed, as well as at the entrance to the plant facility if needed.

7.2 Utilities Extension of the existing natural gas feed to the plant may be required to service new heating as the HVAC design progresses, and an allowance for this cost has been considered. Also, effluent service water and potable water service allowances have been included to provide water to the new facilities as needed.

7.3 Construction Considerations Construction and maintenance requirements for erosion and sediment controls are to comply with Ontario Provincial Standard Specification (OPSS) 577. The contractor will be required to submit an erosion and sediment control plan.

7.4 Landscaping Landscaping will be determined during detailed design. An allowance for landscaping has been included in the conceptual cost estimates.



8. Instrumentation and Control

8.1 Existing Control Systems The existing control system within the plant consists of four Allen-Bradley PLC5/25 programmable logic controllers and two Allen-Bradley ControlLogix PLCs, communicating over a mixed copper and fibre based Data Highway Plus (DH+) network. The controls for the main sewage pumping station that feeds the treatment plant consist of a single Allen-Bradley PLC 5/15 PLC, communicating back to PLC4 in the treatment plant’s admin building over a serial based DF1 network. The plant’s original Allen-Bradley 1771 PLC I/O is distributed about the facility, terminated in the same four control panels housing the PLC5/25 CPUs. The two sludge dewatering centrifuges are each controlled by a ControlLogix PLC and a PanelView Plus operator interface terminal, located in the upper floor of the Dewatering Building.

Two desktop grade SCADA computers utilize GEFanuc iFix 4.0 HMI software for monitoring, control and historical data collection of the various plant processes. Each SCADA computer simultaneously polls all plant PLCs with individual connections to the DH+ network via internal Allen-Bradley 1784-PKTX DH+ communication cards. One computer is located in the main control room within the administration building and the other is located in an auxiliary control room within the Dewatering building. Each PC is configured for both iFix view and server functionality, operating on Microsoft Windows XP, in a small workgroup configuration. At present, iFix support and maintenance is provided both internally by Town of Brockville staff and a local Systems Integrator.

Plant historical data is independently stored, collected and displayed on each SCADA computer, however no permanent automated back-up or historical data synchronization system is in place between the two SCADA computers in the event of historical data loss. Plant operations staff indicated that Historical data is backed up manually with the use of an external USB storage device. Historical trends can be printed from each computer; however no automated reporting system appeared to be in place. Manual, time based historical paper log sheets are maintained in the main control room by Operations staff.

The SCADA PCs and printers are networked together by a 10/100 Mbps copper and fibre Ethernet network, utilizing TCP/IP protocols. Operations staff indicated that for security purposes, no permanent connection exists between the Plant’s SCADA Ethernet network and the Town’s corporate Ethernet network. Figure 9-1 outlines the existing PLC and SCADA system networks and the associated PLC hardware used within each plant process area, including the recent controls refurbishment of the two sludge dewatering centrifuges.

FIGURE 9-1 Existing Plant PLC & SCADA System Schematic



Some existing plant alarms and most remote facility telemetry uses a combination of a now obsolete Modudata alarm annunciation system and a more modern Raco Verbatim Gateway alarm dialler. The various remote facilities utilize smaller Modudata hardware at each site, relaying status and alarms signals over telephone lines to the main Modudata system located at the plant. From this point, these signals are then hardwired to PLC4 in the Administration building. Once the signals and alarms are within this PLC, they are displayed on the iFix computer screens. Critical remote facility and plant alarms are then transmitted by the PLC to the Raco alarm dialler, typically via DF-1 communications, for alarm callout. The existing Raco alarm dialler will be retained for use by the existing systems and those new systems to be added to the plant for secondary treatment. Operations staff also indicated that some remote facility control functionality was intended by use of the Modudata system, however it was never implemented.

Replacement of any remote facility communication systems has not been included in the scope of this project, as the existing Modudata system does not require replacement or modification for the implementation of secondary treatment at the plant. Additionally it is anticipated that this system will not be expanded for use with the plant’s new secondary treatment systems as neither the necessary new components or physical space are available to do so. It is understood from discussions with the plant staff that the City is pursuing replacing the existing remote facility communications systems with either fibre or wireless based communications. Once these upgrades are completed and the various remote facilities can communicate directly with the plant control system (i.e. at the PLC or SCADA levels), the Modudata system would become redundant and it recommended for removal at that time as part of that project.

8.2 PLC Considerations In a number of instances, some existing PLC components used within the control system have effectively reached obsolescence. Some examples include the Allen-Bradley PLC5/15 and PLC5/25 CPUs, having passed their respective “Silver Series” dates on September 30, 2001. This means that these specific components are no longer manufactured, nor are they offered for general sale. In this specific example, these legacy products do have new, readily available replacement components; however they are available at an increased cost and would require some partial re-programming of the existing PLC code before operations could be restored after a failure.

Some specific items identified with the existing systems include:

Desire to update existing PLC5 hardware to more modern PLCs, improving SCADA system performance, minimizing maintenance costs

Poor to non-existent documentation within the existing PLC code making maintenance and troubleshooting very difficult

Staff concerns regarding the “as-built” accuracy of the PLC panel and associated loop drawings

Poor reliability, performance and documentation regarding the existing Fibre DH+ network

Inherent difficulties and limitations with maintain and expanding the existing legacy DH+ networks to properly integrate the new Secondary Treatment control systems

Requirement to expand or replace the existing plant SCADA Ethernet networks to properly integrate the new Secondary Treatment control systems

8.3 SCADA Considerations As previously indicated, the plant’s SCADA system consists of two desktop grade SCADA computers running GEFanuc iFix 4.0 HMI software. Although these computers were replaced when the iFix software was upgraded to version 4.0, the life expectancy of these computers in this 24-hour per day operating environment is typically between three to five years. As such, it may be prudent that these computers are replaced and the iFix software, including its associated drivers, is updated to the latest stable versions, when the new plant processes come on line.

Some specific issues identified with the existing systems include:

Frequent, un-synchronized alarms on one SCADA computer when compared to the second computer



Frequent, un-synchronized trends on one SCADA computer when compared to the second computer

Ongoing software support and maintenance needs

No automated data and system backup system

Minimal physical security of the SCADA computers in the present locations

8.4 Instrumentation In consultation with operations staff, no specific issues or needs were identified regarding instrumentation within the existing facility that requires addressing at this time. Our cursory inspection of the various plant instruments indicated they are suitably maintained and operational. It was noted that some of the facilities electromagnetic flow meters are quite dated and may present issues with obtaining spare parts, however a complete meter replacement can normally be readily sourced from present day manufacturers and suppliers. It was also noted that the specific model of MSA gas detection equipment, located in the electrical room, adjacent to the Screening room, is not longer being manufactured. However spare parts such as the sensing cells and service of these systems remains available. If any specific instrumentation is deemed in need of replacement as part of this project, these can be reviewed on an individual basis with consideration for replacement given to those instruments of highest priority to continued plant operations.

8.5 Control System Recommendations In order to address the items identified for consideration in the preceding text and to better facilitate the addition of the secondary treatment systems controls, Figure 9-2 provides a preliminary conceptual design of the plant’s overall PLC and SCADA systems and networks. New or replaced components are green, while existing components are grey.

The following is a text summarizing the proposed changes and additions in the context of the issues and items identified:

Outright replacement of all PLCs, the associated PLC panels, I/O and field wiring change out is neither justified, nor is it recommended because of the risk associated with extended system downtime during changeover. As such, it is recommended that the existing PLC5 1771 I/O remain in place with new ControlLogix PLCs located in a small panel adjacent to each existing panel, replacing the legacy PLC5 CPUs within each panel

Small, localized ControlNet networks are provided between the new ControlLogix CPUs and each of the existing PLC5 1771 I/O racks

Replacement of the legacy DH+ copper and copper networks between the various PLCs and SCADA computers with a copper and fibre based Ethernet network(s). Note that this will require substantial modifications to the existing SCADA databases as the drivers and corresponding addressing will require changing

Addition of a new SCADA view node located in the new Aeration Building

Addition of various ControlLogix PLCs for the added Secondary Treatment and disinfection systems



FIGURE 9-2 Conceptual Plant PLC & SCADA System Schematic



9. Architectural Design 9.1 General The proposed expansion of the Brockville WPCC would generally include the addition of new secondary treatment facilities with ancillary facilities such as access tunnels, and electrical service/communications service buildings, and possible miscellaneous upgrades to the existing plant. The majority of the expansion work would consist of open tanks that are semi recessed into the terrain with modest control building or buildings between the tanks.

The exterior cladding of the new buildings would be in keeping with an expression similar to the existing facility. The intent would be to use exterior cladding finishes and colours that will compliment, and visually integrate the new structures into the existing facility.

9.2 Operations and Staff Facilities As part of the secondary upgrade renovations to the existing staff facilities including the change rooms will be required to accommodate additional staff members. Additionally, consideration of a new lab facility and storage space integrated into the facility should be made in order to accommodate the additional testing required for process control of a secondary treatment plant.

9.3 Design Codes and Standards The secondary treatment facility would need to have an occupied gallery level. Ontario Building Code (OBC) Article 3.2.2 determines the most restrictive major occupancy. Due to the nature of the new facility, it is assumed that the classification would be F-2 Medium Hazard Industrial.

According to Article 3.2.2.71 of the OBC, this building does not require sprinklers and may be of combustible or non-combustible construction. Floor assemblies would be fire separations, but require a 45-minute rating only if made of combustible construction materials. Supporting structures would be rated at 45-minutes, or be non-combustible. It is intended that the structure be of non-combustible construction and, therefore, it will conform to the requirements of Article 3.2.2.71.

Exits would be designed to conform to Ontario Building Code (OBC) Article 3.4.2. The distance between exits would not exceed the figures as outlined in this section of the OBC.



10. Structural Design 10.1 General The structures (i.e. tanks, tunnels, etc.) will be constructed on cast-in-place reinforced concrete foundation walls with strip footings or flat slabs. For the preferred site layout, due to existing grades, the structures would likely have to be over excavated and placed on engineered fill. For structures bearing on engineered fill post construction total and differential settlements should be less than 25 and 15 mm respectively. For structures bearing on bedrock differential settlements of the structures should not be a concern.

The high river water level is assumed to be at elevation 75.0 metres above sea level (masl) based on discussions with the City’s soils consultant. The founding elevation of all of the structures would be significantly higher and, therefore, rock anchors, to resist buoyancy would not be necessary. During construction, seepage of some surface or subsurface water is anticipated but should be manageable with perimeter ditches. A permanent drainage system should be installed to alleviate any hydrostatic head against the structures. The below grade structures adjacent to any dry areas (e.g. galleries, tunnels, basements) will be waterproofed on the exterior. Chemical waterproofing will be applied to the tank walls and slabs adjacent to the dry areas.

10.2 Design Codes and Standards The design of all structural aspects of the new and upgraded works will be governed by the applicable requirements of the latest edition of the following codes and standards:

Ontario Building Code

CSA Standard A23.3-04

All liquid retaining structures will be based on the applicable requirements of the ACI 350-01 “Code Requirements for Environmental Engineering Concrete Structures,” as applied to the Canadian design standards and codes

CSA Standard S16-01, Limit States Design of Steel Structures

CSA Standard S157-05, Strength Design in Aluminum

CSA Standard S304.1-04, Design of Masonry Structures.

10.3 Materials Concrete will conform to CAN/CSA A23.1 “Concrete Materials and Methods of Concrete Construction.” Typical compressive strength for tank structures would be 32 MPa with a maximum water/cementing material ration of 0.45, nominal maximum size of coarse aggregate of 20 mm and an air content of 5 to 8%. Steel reinforcement should conform to CSA G30.18, Grade 400 deformed billet steel.

Structural steel will conform to CAN/CSA G40.21 “Structural Quality Steels.” Hot rolled structural sections and plates will be to Grade 350W. Stainless steel sections and plates will generally conform to Type 316 and aluminum sections and plates will conform to Aluminum Alloy 6061-T6.



11. Electrical Design 11.1 Existing Power Distribution The utility supplies the Brockville WPCC site from a pole line (4800 Volts Delta) that runs parallel to the site access lane on the east side of the site. This pole line is connected to the Hydro One pole line located alongside Highway #2. The site pole line terminates in three pole mounted 167 kVA fluid filled transformers. These transformers are believed to be owned by Hydro One Networks. Three 167 kVA transformers provide a capacity of 500 kVA or 600 Amps at 600 Volts. The transformer pole is located approximately 110 m north of the dewatering building. The transformer secondary conductors (600/347 V Wye) are contained in a buried concrete encased duct bank which leads into the dewatering facility and connects to MCC No. 5 on the second floor. MCC No. 5 contains a utility metering section that connects to a kilowatt-hour meter located on the exterior east wall of the building at ground level.

MCC No. 5 distributes the site 600 Volt power to the loads in the Dewatering Facility and MCCs located in the other buildings. These other building MCCs are MCC No. E2 in the West Service Building, MCC No. 1 in the Digester Facility, MCC No. 3 in the East Service Building, and MCC No. 6 in the Screen and Grit Facility.

During a site inspection (Dec. 14 2007), MCC No. 5 was observed to have a load of 200 Amps. In discussions with site personnel, 200 to 300 Amp loads are considered to be average.

MCC No. E2 located in the West Service Building contains a standby power transfer switch. This transfer switch receives its standby power from a 75 kVA diesel power generator located in the same room as the MCC. Normal or utility power is supplied from MCC No. 5. MCC No. E2 supplies standby power MCC No. E1 in the Digester Facility, MCC No. E3 in the East Service Building and MCC No. E6 in the Screen and Grit Facility.

Anticipated loads for the new secondary treatment plant are between 450 and 550 kW and will require finalization during preliminary/detailed design.

11.2 New Power Distribution The existing overhead lines and pole mounted transformers will likely interfere with the construction of the new facility as the overhead line runs across the area that may be utilized as a construction staging area. Therefore it is proposed that consideration be given to temporarily relocating the existing overhead line to accommodate the construction of the new facility. This temporary line and the existing pole mounted transformers would be removed once the new utility service is ready.

The existing power service to the Brockville WPCC is insufficient to support the anticipated increased load, therefore it is proposed that a new overhead line be constructed to supply a pad mounted transformer located adjacent to the new secondary treatment facility. The transformer is expected to be approximately 1,000 kVA in capacity. To allow for additional future capacity it is suggested that the transformer be equipped with fans to utilize the additional capacity provided by a transformer with a forced cooling rating.

In addition to the new overhead line to feed the on-site transformer from Highway #2, Hydro One will be required to upgrade the off-site service from approximately 2 kilometres away, where the nearest available high capacity line is located. The City of Brockville has initiated discussions with Hydro One to begin their design of this off-site facility, so that this design is available for the detailed design phase of this project in future.

The transformer secondary output (600/347 Volts) will connect to the new facility electrical room through a buried duct bank. A distribution switchboard with utility metering section will distribute the power to both the new and existing facility. It is anticipated that a 600 Amp feeder will supply the existing MCC No. 5. A second 700 Amp feeder will supply the new facility main motor control center through an automatic transfer switch. As it is supplied through an automatic transfer switch, the new facility motor control center will continue to supply all loads under generator power when utility power is unavailable.

The new service entrance switchboard, transfer switch and motor control center should be installed in a dedicated electrical room. It is anticipated that future changes to the Ontario Electrical Safety Code (Arc Flash and Associated Personal Protective Equipment Requirements) will be in place by the time this plant is being designed and constructed.



11.2.1 Distribution Typical distribution conductors will be armored Teck cable in tray. Conductors in hazardous areas will be conductor in rigid conduit with appropriate seals as it enters these areas.

Distribution panels and step down transformers will be located in the main electrical room or non hazardous areas to avoid hazardous environment conflicts.

11.2.2 Lighting Lighting will be manually switched fluorescent. Fixtures will be sealed as required for the hazardous or damp areas.

11.2.3 Emergency Supply It is proposed that a new 750 kVA 600 kW 600/347 Volt diesel generator in a self contained, sound attenuating walk in enclosure is installed as the source of emergency power. Consideration of diesel versus natural gas for standby power must be made with respect to the City’s risk tolerance for fuel supply. The generator would be located on a concrete pad adjacent to the new facility. Due to the close proximity of residential areas a critical or hospital grade silencer is suggested to attenuate the exhaust noise. A minimum of 24 hours of fuel storage would be provided within the enclosure. A generator of this size will support secondary treatment and the existing primary treatment plant. The existing generator is near the end of its useful life, therefore, it is recommended it be removed. One of the VE proposals included a suggestion to optimize the potential standby power requirements, which is recommended for further consideration during preliminary design, and could offer savings in the sizing of the generator (i.e. a smaller generator if making use of the existing generator). Also, a review of standby power requirements with respect to items such as waste gas utilization for off-setting of boiler replacement in conjunction with cogeneration could be reviewed during preliminary design, in the context of this project as a whole.

Typical ultraviolet disinfection equipment operates at 480/277 Volts. Therefore appropriate step down transformers and distribution should be provided to support the recommended UV equipment. Supplied from the new MCC, the disinfection equipment will be supported with emergency power in the event of a utility power failure.

11.2.4 Power Factor Correction The largest percentage of the new load is motors. To prevent a poor power factor (Motor power factor is typically 0.8 lagging and utilities require a 0.94 lagging power factor to avoid penalty.) and the resulting cost penalty on the utility charges, a system of power factor correction using a staged, transient free capacitor bank located in the electrical room of the new facility is proposed. A staged bank is preferred to a group of fixed capacitors sized to each individual motor because the staged bank may be tuned to minimize the impact of power system harmonics.



12. Building Mechanical Design 12.1 Heating Existing/new boilers for the facility would provide hydronic heating to new areas (i.e. secondary treatment and disinfection occupied spaces) and consist of a combination of the following:

Convectors, cabinet heaters, baseboards for administration/non-process areas;

Unit heaters in the process areas;

Glycol heat exchanger serving make-up air and air handlers requiring freeze protection.

Hot water supply and return piping would be distributed through existing and new tunnels to the necessary locations. Glycol heat exchangers would be located locally at facilities requiring the use of a freeze resistant media for make-up air requirements.

12.2 Ventilation Ventilation would be provided to meet expected occupational loads and be designed to meet the latest Ontario Building Code (OBC) and American Society of Heating, Refrigeration and Air Conditioning (ASHRAE) 62 standards for administration/non-process areas. Process areas/pipe galleries would be ventilated in accordance with National Fire Protection Association (NFPA) 820 Standard for Fire Protection in Wastewater Treatment and Collection Facilities. Ventilation of process areas not having defined minimum code ventilation rates but potentially posing health risks to personal would be considered as required (ex. enclosed/covered tanks).

12.3 Odour Control Generally odour control is provided at the headworks and dewatering areas of a wastewater treatment plant, and no change to the existing facilities have been identified as part of the secondary upgrade. New odour control should be considered for the proposed WAS thickening, digested sludge storage and centrate equalization facility. There are also alternative possible operations procedures that could be used in place of the requirement for odour control such as flushing of the WAS thickening pipes following operations and/or use of a sodium hypochlorite system for periodic cleaning of the lines.

12.4 Plumbing Separated storm and sanitary drainage would be provided for new facilities per OBC standards. The existing treated effluent water system would be used to meet process requirements (wash down, etc.) for new areas and tanks. Potable water would be distributed to new facilities as required and be designed per OBC standards.

12.5 Life Safety A sprinkler/standpipe system would not be required for new areas. Fire extinguishers would be provided and distributed throughout facilities per NFPA 10 Standard for Portable Fire Extinguishers. Requirements for emergency eyewash/showers and tempered water systems per American National Standards Institute (ANSI) Z358.1 Standard for Emergency Eyewash and Shower Equipment would be evaluated and provided as necessary for areas where operators will be expected to handle chemicals.



13. Implementation Schedule A project implementation schedule is outlined in Table 13-1. This schedule is for planning purposes, and provides a typical schedule for implementation of a project of this scale.

There are a number of opportunities that could be used to compress this schedule, including short duration on consultant selection for design and tender document completion, consideration of shortening preliminary design by limiting items such as existing plant reviews (carry these out prior to design), limiting pre-selection packages and a possible advance site preparation construction contract. These types of schedule acceleration items should be addressed early during the preliminary design stage.

Contractor pre-qualification was recommended as an outcome of the VE workshop, and this should be planned to occur concurrently with the tender document preparation in order to limit any impact with respect to lengthening of the project schedule.

TABLE 13-1 Typical Project Implementation Schedule for Planning Purposes

Activity Projected Date Duration (months)

Select Design Consultant and Project Kick-Off Mid February to Mid April, 2008 2

Preliminary Design End of October 2008 6

Detailed Design/Tender Document End of June 2009 8

Tender and Award of Construction Contract End of September 2009 3

Complete Construction End of September 2011 24

Commissioning End of January 2012 4



14. Project Costs The project cost budget from the EA was estimated at $28M to $36M (2004 dollars). This included a $15-20M allowance for secondary treatment upgrade, and $10-12M for existing plant upgrades. An objective of this conceptual design is to establish the project cost estimate based on the scope defined in the Request for Proposal and this report. This cost does not included engineering and project management costs.

A summary cost table in Appendix F provides a breakdown of each option evaluated in this study and each combination of technologies, i.e. CAS with UV or chlor/dechlor, and BAF with UV or chlor/dechlor.

At this conceptual design level, the estimated total project cost to implement secondary treatment for the recommended option of CAS with UV disinfection is $43M.

Detailed cost breakdowns are included in Appendix F, and are subject to the design basis and assumptions previously outlined.

14.1 Cost Estimating Basis and Assumptions The estimated costs for capital and operations and maintenance for this project have been completed based on the conceptual design and assumptions as stated in previous sections. At the conceptual level of design, the cost estimate is considered to be between a Class D and Class C estimate, per the definitions provided by Public Works Canada, outlined as follows.

Class A Estimate This is a detailed estimate based on quantity take-off from final drawings and specifications. It is used to evaluate tenders or as a basis of cost control during day-labour construction.

Class B Estimate This estimate is prepared after site investigations and studies have been completed and the major systems defined. It is based on project brief and preliminary design. It is used for obtaining approvals, budgetary control and design cost control.

Class C Estimate This estimate, which is prepared with limited site information, is based on probable conditions affecting the project. It represents the summation of all identifiable project component costs. It is used for program planning, to establish a more specific definition of client needs and to obtain approval-in-principle.

Class D Estimate This is a preliminary estimate, which due to little or no site information indicates the approximate magnitude of cost of the proposed project, based on the client’s broad requirements. This overall cost estimate may be derived from lump sum or unit costs as identified in the construction cost manual for a similar project. It may be used to obtain approval-in-principle and for discussion purposes.

Appendix F contains the cost estimating work sheets completed for this study. The total cost estimate was prepared using the following bases and assumptions:

Costs are 2008 dollars

Building estimates are approximated from their size and type of construction using per square meter costs

Equipment estimates are based on historical data or vender quotations from recently tendered wastewater projects with allowances for installation based on percentage of the equipment cost

Detailed equipment, electrical, heating and ventilating, process piping, etc. layouts will be completed during detailed design, therefore, costing for these items has been done at a conceptual level, with an allowance for conservative quantities with unit prices based on recent tender information from similar projects

Contractors Markup: 15% (10% overhead, 5%) based on recent projects in construction in the Ottawa area



Conceptual Design Contingency Allowance: 30%

Concrete: unit prices based on current market conditions however metals markets are very volatile

Excavation: $100/m3 for rock blasting, based on recent tender pricing

Project management costs at $700,000 per the City of Brockville Council briefing

Engineering Costs (Design and Construction): representative costs of 20% of project cost included

The following items are excluded from the cost estimates:

City of Brockville internal costs

GST

Removal of hazardous waste (it is assumed there will be no hazardous material encountered during excavation)

Additional costs for various approaches for accelerating construction, if desired (i.e. multiple construction contracts, design/build, pre-selection, etc.)

14.2 Impact of Escalation and Market Conditions

14.2.1 Escalation to Time of Construction An escalation rate of 3% per year is assumed based on CH2M HILL’s internal tracking of construction costs by our cost estimating professionals. An escalation allowance of 6.8% has been used (or 27 months @ 3% per year = 0.25% per month). This assumes that from January 2008 (time of writing of this report) to the mid-point of construction is April 2010, which is approximately 27 months. This is subject to change based on the final project schedule.

14.2.2 Construction Market In the current construction market, contractors are generally busy which, in turn, reduces the competitiveness which could increase tendered amounts. Additionally, the prices of some commodities (such a steel and copper) are very volatile. It is difficult to predict the impact of these market conditions. An allowance of 2% has been included as a construction market allowance.

14.2.3 Contingency Allowance A mark-up of thirty percent for contingency has been included. This contingency allowance is based on an expected four levels of cost estimates being prepared. The total contingency mark-up will decrease as the design develops and more information is available as shown in Table 14-1. At the conceptual design phase, the level of design is not totally defined; therefore the 30% allowance was carried as a design development contingency. This contingency is not intended to be used for additions to the scope of work, such as additional upgrades to existing works or increases in plant capacity, etc. but is to account for unforeseen items that cannot be accounted for at this conceptual stage of design.

TABLE 14-1 Contingency Allowance Carried in Cost Estimate

Cost Estimate Level Total Contingency Allowance Carried

in Cost Estimate

Conceptual Design 30%

Pre-Design 20%

Detailed Design 15%

Pre-Tender 10%



15. Conclusions and Recommendations The following are the conclusions and recommendations of this study:

Implementation of the secondary treatment upgrade project at the Brockville WPCC move forward to preliminary design, detailed design and construction using conventional activated sludge and UV disinfection.

The recommended site layout is provided in Figure 4, following this page. The recommended process flow diagram and typical equipment layouts used as a conceptual basis for this study are also included following this page.

The cost of secondary treatment and disinfection upgrades, including modifications to the existing plant to incorporate secondary treatment is estimated as a Class C/D cost estimate at $43M.

Remaining funds are expected to be available for use to rehabilitate or upgrade priority items to improve operations at the existing facility therefore increasing operational efficiency and/or water quality. These upgrade items should be included in the design project and as provisional items in the construction tender pending the results of the tender bids, allowing the City to select items as appropriate based on the tender prices for the secondary treatment and disinfection project. The amount of available funds will be further determined as more detailed cost estimates for the secondary treatment and disinfection portion of the project are refined during preliminary and detailed design.

The following items are recommended for further review in the design and construction project, resulting from Value Engineering proposals:

Investigate potential to incorporate new coagulation chemical facilities within the new secondary treatment plant construction – Value Engineering Proposal #4.

Inclusion of suggested program delivery items in the project management approach - Value Engineering Proposal #14.

The following items should be reviewed during preliminary design:

Flows to the existing plant through a flow metering study to ensure a firm design basis.

Standby power, cogeneration, and associated waste gas systems including possible boiler replacements in order to address these upgrades and costs as a whole.

Condition assessment of the existing primary clarifiers.

Condition assessment of the existing digesters.

Inclusion of laboratory, maintenance and storage space within the new secondary treatment facilities.

Interior inspection of the outfall to confirm good condition.

Review of the geotechnical report should be completed during preliminary design to confirm assumptions regarding foundation requirements and excavation requirements for tankage.

Design of the off-site electrical feed upgrade by Hydro One. This should be initiated as soon as possible by the City to ensure this design is complete during preliminary design as a basis for the electrical site layout requirements.


CONVENTIONAL ACTIVATED SLUDGE

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