irwp seasonal storage project water reuse system storage model

RDD/070330003 (SYSTEM_STORAGE.DOC) WB012007008RDD 1

T E C H N I C A L M E M O R A N D U M

IRWP Seasonal Storage Project Water Reuse System Storage Model

PREPARED FOR: City of Santa Rosa

PREPARED BY: Rob Tull/CH2M HILL Jason Lillywhite/CH2M HILL

REVIEWED BY: Doug Smith/CH2M HILL Ted Whiton/Winzler & Kelly Marc Soloman/Winzler & Kelly

COPIES: Dave Smith/Merritt Smith Consulting Pat Collins/Winzler & Kelly Mark Millan/Data Instincts

DATE: November 29, 2007

Background and PurposeThe existing Water Balance Model (WBM) utilized during the Incremental Recycled Water Program (IRWP) feasibility study and master planning work identified the need for addi-tional seasonal storage to support additional reuse projects. However, a more detailed simulation was still needed to better define the operational interaction between existing and potential future storage ponds within the envelope of the IRWP demand and discharge scenarios developed in the IRWP. The Seasonal Storage Project (SSP), therefore, included a Storage Planning Model (SPM), as described in this technical memorandum (TM).

The purpose of this TM is to document the data collection, model approach, assumptions, and operational rules used to build the SPM for the Santa Rosa Subregional Water Reuse System (Subregional System). This TM also summarizes the model results for the seven storage and five demand scenarios evaluated in the storage analysis.

The SPM was developed to conduct a screening-level evaluation of the Subregional System’s seasonal storage options under alternative future storage location, sizing, and demand scenarios. The results of the model show how alternative storage site locations perform if integrated into the existing Subregional System. The model simulates the existing and future system response to changes in urban demands, agricultural demands, flows to the Geysers, and discharge disposal strategies.

The model was applied to potential additional storage sites, including the following sites:

� Alpha Pond � Brown Pond � Kelly Pond � West College Pond

IRWP SEASONAL STORAGE PROJECT WATER REUSE SYSTEM STORAGE MODEL


� Alexander Valley Road Pond � Petaluma Hill Road Pond

The West College and Alexander Valley Road Sites are not considered further because of findings from the geotechnical investigations indicating uncertainty related to potential impacts from liquefaction, fault zones, and/or landslides and the appropriate measures to mitigate for these potential hazards. Based on the geotechnical findings at these sites, both are considered infeasible as defined by CEQA Guidelines, as described in the TM Geotechnical Evaluation, November 2007.

This TM covers the following topics:

� Background and Purpose � Conclusions and Recommendations � Study Area and Modeling Approach � Analytical Approach � Existing System Data and Pond Operations � Existing Conditions Model Formulation and Verification � Future Model Formulation � Future Conditions Model Results

Conclusions and Recommendations The following conclusions are based on evaluation of the results from the future conditions model:

� Location of Future Ponds: Through simulations of all pond location scenarios, it was found that storage location does not affect the volume of future total system storage capacity needed nor the ability to discharge.

� Additional Volume Requirement: The range of additional storage volume required for the scenarios run in the future conditions model (under five different hydrologic water years ranging from dry to wet, where a water year is defined as starting on October 1 and ending on September 30) is between 200 and 650 million gallons (MG). The additional volume required is based on an existing maximum operational storage volume of 1,436 MG.

� Pipe and Pump Capacities: Increasing the capacity of the pipeline from Meadow Lane Pond to Delta Pond could reduce the discharge from Meadow Lane Pond complex to the Laguna de Santa Rosa (Laguna). Some other minor facility upgrades might be required as part of pond enlargements under a given pond scenario, such as piping for draining ponds.



Study Area and Modeling Approach Study Area The study area for the SPM includes the Laguna Subregional Water Reuse Facility (Laguna Plant), all existing reuse storage ponds, major transmission pipelines, pump stations, and the Geysers supply pipeline to the point of delivery.

The system is divided into five zones (used for flowmeter reading) where recycled water is applied for irrigation from the Laguna Plant. The Rohnert Park urban reuse areas are in addition to these five zones. Figure 1 is a map showing the study area, including major conveyance facilities and the five demand zones. Recycled water in the Subregional System comes from the Laguna Plant and is delivered to irrigated areas shown on Figure 1. Water that is not immediately used for irrigation is stored in ponds located throughout the system. Water can be discharged into the Laguna from Meadow Lane Pond complex and Delta Pond at certain times of the year under given discharge constraints.

Summary of General Approach The SPM was built in two phases, with the first consisting of an existing conditions model and the second, a future scenario model. The SPM was built on information provided by the City of Santa Rosa and an existing simulation model called the WBM. Some of the results of the SPM related to operational and hydraulic constraints will be used in coordination with a separate reuse system Hydraulics Model, which will then provide input to the Urban Reuse Hydraulics Model. Figure 2 illustrates how these models work together.

The following steps were taken in building the SPM:

1. Develop an understanding of the existing system.

2. Collect hydrologic, physical system, and operations data.

3. Develop a daily time-step existing conditions model to verify the SPM’s ability to adequately simulate the operation of the storage ponds from October 2003 through October 2006.

4. Modify the existing conditions model with logic used in the WBM to allow simulation of alternative future pond storage and demand scenarios.

5. Conduct simulations of five different hydrologic years for each alterative future pond storage and system demand scenario.

GoldSim Pro Software The SPM needed a flexible software platform or tool to simulate multiple decision processes and operational rules for a complex system of ponds connected by pipelines and pump stations. This tool also needed to provide output that would allow for easy evaluation of alternative storage and demand scenarios.

GoldSim was the chosen software because it provides a highly effective and flexible simula-tion platform for visualizing and dynamically simulating physical, financial, or organiza-tional systems. This software allows models to be built in an intuitive manner by literally



drawing a picture (an influence diagram) of the system. The user can graphically create and manipulate data and equations within a series of linked elements or dashboards.

RohnertPark

PumpStation

LagunaSubregional

WaterReclamation

Facility

FIGURE 1SANTA ROSA SUBREGIONALWATER REUSE SYSTEM

WB012007018RDD_01 (2/27/07)

High/Low PressureReuse PipelineGeysers Pipeline

Irrigation Areas



FIGURE 2

Illustration of Overall Model Coordination

WBM

� Rules for allowable discharge and required storage

� Plant flows � Hydrology � Irrigation demand patterns � Future reuse demands, schedules, priorities

Storage Planning Model

Hydraulics Modela

� Pipeline peak capacities � Pump curves � Pressures and elevations

� Simulates pond volume transfers and flow rates between ponds

� Incorporates rules governing transfers � Includes all ponds in system � Include existing users and associated

demand patterns � Does not calculate river flows or plant

outflows � Future reuse demands, schedules, priorities

Urban Reuse Hydraulics Modelb

Confi

rms c

apac

ity

avail

able

� Required storage under various operations or geographic scenarios Coordinate

Major Coordination ComponentsModel Relationships

Check results and logic

Notes:aThe Hydraulics Model simulates the pipe network system that interconnects all of the ponds. This model will be used to evaluate and confirm pump and pipe capacities and also to check pressure requirements. bThe Urban Reuse Hydraulics Model will be similar in function to the Hydraulic Model, but it is focused on the proposed Urban Reuse system. This model will be built using the Hydraulics Model as the foundation and will be supported by the results of the Storage Planning Model.



Analytical Approach The following steps were taken in building the SPM:

1. Develop an Understanding of the Existing System.

The first step in building the SPM was to develop an understanding of the existing system. This step included formulating a general layout of the existing system based on previously created schematic diagrams. This general layout includes flow directions from the Laguna Plant to the ponds and from ponds to demands. This basic understanding was developed through discussions with Reclamation Superintendent Randy Piazza.

2. Collect Hydrologic, Physical System, and Operational Data.

The next step was to gather the pertinent hydrologic, physical system, and operational data critical to building the model of the existing system. The data obtained was for the period October 2003 through October 2006 and was the basis for the existing conditions model run.

3. Develop Existing Conditions Model.

The purpose of the existing conditions model was to verify the model’s ability to adequately simulate the system. During this step, some inconsistencies in the data were noted for operations in the years 2003 through 2006. These inconsistencies were taken into account in the model verification process and, in some cases, the model results did not exactly match historical operations. However, on an overall basis, the results from the existing conditions model matched historical operations of the system very closely for the period 2003 through 2006. This demonstrates the model’s ability to simulate the complex operations of the Subregional System.

4. Develop Future Conditions Model.

The existing conditions model was modified to incorporate the capability to simulate the operation of alternative future conditions. This includes simulation of proposed storage site locations and pond volumes, changes in operations, increased demands, changes in receiving water quality constraints, and increased Laguna Plant production. To simulate the ponds, dynamic storage rule curves were developed to control and balance simulated pond inflows, pond outflows, and discharges to reuse activities or the Laguna. These storage rule curves are made up of multiple volume or level target points that change seasonally to help “guide” the operations of a storage facility. In general, these curves are used to guide decisions regarding storage facility operations, such as increasing storage or outflows. The dynamic storage rule curves used in the SPM adjust, depending on the hydrology, and provide a continuous target storage level for each pond that triggers when to begin storing water, controls discharge timing, and allocates water to demands.

5. Conduct Future Scenario Simulations.

The future conditions model was used to evaluate multiple demand and storage scenarios. Scenarios included six different future pond configurations (one of which includes no increase to overall storage capacity), and five future demand levels. Each scenario was simulated for five years representing a range of driest to wettest hydrologic conditions (as established by the WBM).



Existing System Data and Pond Operations A meeting was held with Randy Piazza on October 10, 2006, to discuss operational parame-ters and practices used to operate and maintain the reuse system. A field visit to the major Subregional System facilities was also conducted. The following section briefly describes the operations and physical facilities of the system as they relate to the development of the existing conditions SPM.

Summary of Data Obtained for the Existing Conditions Model 1. Physical characteristics of the existing ponds (storage volume, fill/drain rates) 2. Demand scenarios, priorities, categories (zones and ponds), and patterns 3. Operational rules and criteria for filling and draining storage ponds

Table 1 summarizes all of the data collected for the existing conditions model.

TABLE 1List of Data Obtained for the Existing Conditions Model IRWP Seasonal Storage Project – Water Reuse System Storage Model

Type Description Dates in Set Time-Step

Total pond storage volumes with lower, upper, and maximum boundaries

Jan 1, 2004 – Oct 10, 2006

Daily

Stage-volume curves for each pond N/A N/A

Pond storage volumes for Meadow Lane, Delta, West College, and small ponds (combined smaller ponds)

Oct 1, 2003 –Sep 30, 2006

Daily

Storage

Summary of operational ranges of storage at individual ponds N/A N/A

Geysers flow data Oct 1, 2003 – Sep 30, 2006

Daily

Irrigation water use separated by zones and ponds (accumulation of many files)

Sep 1, 2003 – Sep 30, 2006

Monthly

Crop ET (Bennett Valley) Oct 1, 2001 – Sep 30, 2006

Daily

Demands

Typical demands on Delta Pond system N/A Monthly

River discharge Oct 1, 2003 – Sep 30, 2006

Daily

Russian River flows at Guerneville Oct 1, 2003 – Oct 16, 2006

Daily

Pond discharge flows (including Alpha, Brown, Kelly, Laguna de Santa Rosa [Laguna], Delta)

Jan 1, 2000 – May 3, 2006

Daily

Documentation of how 2005-2006 Laguna flows at Delta were estimated

N/A N/A

Laguna flows near Delta Pond Oct 1, 2003 – Sep 30, 2006

Daily

Laguna water surface elevation near Delta Pond Oct 1, 2003 – Sep 30, 2006

Daily

River & Discharge

Russian River Flows at Hacienda Gage Oct 1, 2003 – Sep 30, 2006

Daily



TABLE 1List of Data Obtained for the Existing Conditions Model IRWP Seasonal Storage Project – Water Reuse System Storage Model

Type Description Dates in Set Time-Step

Climate Precipitation and pan evaporation measured at the Laguna Plant (includes temperature data)

Oct 1, 2003 –Oct 13, 2006

Daily

Water Balance data (summary data – current typical and historical maximum)

N/A Monthly

Five year types used in Legacy Model (WBM) Varies Daily

Water Balance

Documentation of Legacy Model setup N/A N/A

Other Maps of Subregional System N/A N/A

Documentation of 2004 Sonoma County Water Authority (SCWA) water usage

2004 Monthly

Documentation of 2005 SCWA water usage 2005 Monthly

Documentation of 2006 SCWA water usage 2006 Monthly

SCWA transfer in water usage summary Oct 1, 2003 – Sep 30, 2006

Monthly

Flow In

Laguna Plant effluent flow data Aug 1, 2003 – Oct 16, 2006

Daily

Existing Operating Information and Rules The following is a summary of information and general rules that were applied in operating the existing pond system:

� Total system storage goal at the end of the irrigation season is about 120 MG.

� The total system storage goal at the beginning of the irrigation season is around 1,350 MG. The total maximum operational storage volume is 1,436 MG.

� In pre-Geysers years (before 2003), an average of four cuttings of hay were made on City farms during the irrigation season. In the post-Geysers period, there was only enough water to provide for two cuttings on City farms, resulting in an abbreviated irrigation season in which water deliveries end around July 1.

� Typically, the system storage target for March 1 is 1 billion gallons. The amount of rain after this date will determine whether the operator will continue storing or discharging water.

� The drawdown operations of Meadow Lane Pond and Delta Pond, which occurs late in the irrigation season, is coordinated so that the volumes of both ponds are approximately equal between August 1 and October 1.

Year 2005 was considered by operations staff to be more of a typical (or average) year for operating the system. Year 2004 was considered drier than normal with a very dry spring, and year 2006 was considered to be a very wet year. The last 3 years provided a good range of hydrologic conditions. The Geysers Pipeline did not come into operation until the end of



2003, which needs to be considered when analyzing this information, because the Geysers Pipeline has a significant impact on total recycled water usage.

Laguna Plant Production and System Discharges Laguna Plant daily production was obtained directly from Supervisory Control and Data Acquisition (SCADA) records. Figure 3 is a plot of these data from October 2003 through September 2006.

0

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2004 2005 2006

WW

TP

Pro

du

cti

on

(M

GD

)

Time (Years) FIGURE 3

Laguna Plant Flows (Oct 2003 – Oct 2006)

Daily system discharge flow rate records from October 2003 through September 2006 are shown on Figure 4. Values shown represent total discharge from the Subregional System.

0

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2004 2005 2006

Dis

ch

arg

e (

mg

d)

Time (Years) FIGURE 4 Recorded Discharge (Oct 2003 – Oct 2006)

HydrologyHydrology data collected for the existing conditions model include daily flow records in the Russian River at the Hacienda Gage from October 2003 through September 2006. This information was obtained from Merritt Smith Consulting and is shown on Figure 5.



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2004 2005 2006

Flo

w (

1,0

00

cfs

)

Time (day) FIGURE 5 Russian River Flow at Hacienda Gage (Oct 2003 – Sept 2006)

Climatic Data Climatic data used for the existing conditions model include evaporation and precipitation. This information was obtained from Laguna Plant records and was used to calculate the net loss or gain at each pond as a result of evaporation and precipitation. Pan evaporation data recorded at the Laguna Plant was converted to pond evaporation using a pan coefficient of 0.7 (typical range is 0.65 to 0.85). Evaporation and precipitation are applied in inches to the pond water surface to estimate the volume of net loss or gain. Figure 6 is a graph of the daily net sum of precipitation and evaporation used in the existing conditions model.

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-10

0

10

20

30

2004 2005 2006

Net

Eva

pora

tion

/ Pre

cipi

tatio

n (in

)

Time (day) FIGURE 6 Net Evaporation and Precipitation (Oct 2003 – Sept 2006)

Data Validation A monthly systemwide water balance was conducted using existing recorded field data by accounting for flow into the system minus flow out of the system and comparing that net flow volume to the change in total system storage. The existing data used in this procedure included irrigation demands, Laguna Plant production, discharge rates, and storage volumes for water years 2004 through 2006. The water balance results are shown on



Figure 7, where inflow minus outflow is compared to monthly changes in total system storage. The results indicate reasonable agreement with some expected variation, likely caused by the relative accuracy of the various data collection methods and typical data measurement uncertainty associated with flowmeter error, accuracy of pond depth/storage rating curves, measured evaporation/ precipitation rates, and pond level measurements. No evidence exists of any particular bias in the data, indicating that the data error is generally balanced and does not accumulate over time. The months with the greatest deviation occur in December 2003 and January of 2004, which coincide with the approximate time that the Geysers Pipeline first became operational.

The results of the water balance analysis provided an adequate data set for developing and verifying the existing conditions SPM. The observed data for October 2003 through September 2006 were used as the basis for evaluating the SPM’s ability to simulate the general operations of the existing system. The October 2003 through September 2006 data set was not used in the future conditions analysis, which incorporated hydrologic information from the WBM for five specific year types representing a range of different hydrologic conditions.

-600

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-200

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Mil

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all

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Qin-Qout

Change in Storage

FIGURE 7 Existing Water Balance Comparison

Existing Conditions Model Formulation and Verification A model verification process was conducted for the existing conditions model based on system storage and discharge data for water years 2004, 2005, and 2006. Water years used in



the SPM start on October 1 and end on September 30. This process confirmed the existing conditions model’s ability to simulate the existing system.

Existing System Configuration Figure 8 shows a schematic diagram of the existing reuse system. Water from the Laguna Plant flows directly into the Meadow Lane Pond complex, which includes the pumps feeding the agricultural and urban reuse systems (EA and EB pumps) and the pumps feeding the Geysers (Llano Pump Station). Water from the plant can either be distributed using these pump stations, or stored in the Meadowlane Ponds. From the Meadow Lane Pond complex, water is sent in the following three directions:

1. To Zones 2 and 3, then to the Delta/West College System and Zones 4 and 5 2. Geysers 3. Rohnert Park System and Zone 1

The EB pumps are used to lift water to the irrigation demand zones within the Subregional System (and Delta Pond), including the south end of Zone 1 and Rohnert Park demands. Within the Rohnert Park system, the Rohnert Park Pump Station lifts water to Rohnert Park high-pressure demands and to Gallo Pond. The EB pumps also pump water north of Meadow Lane Pond to Alpha, Brown, Kelly, and Lafranconi Ponds and to Zone 1, 2, and 3 demands.

Delta Pond supplies water to the Delta/West College system and is lifted through the Delta Pump Station to Ambrosini Pond, Place to Play, West College Ponds and Zones 4 and 5 demands. Currently, some water from the Sonoma County Water Agency transfers into the system, but it is anticipated that this will not continue in the future. The Delta Pump Station is operated to maintain target water levels in West College Pond. The North Pump Station is located to the north of Delta Pond and supplies water to several private farmers. The demands supplied by this pump station were included in the model, but the actual operations of this pump station were not simulated.

Existing Conditions Model Logic The existing conditions model runs on a daily time-step for 3 consecutive water years starting on October 1, 2003, and ending on September 30, 2006.

At each pond, the model flow logic is as follows: outflow from the pond is the given irriga-tion demand plus pond evaporation, inflows are calculated according to controls that change throughout the year, and the controls are intended to provide a certain amount of storage in the pond that is similar to historical operations. The historical operations are summarized in the next section. Precipitation on the ponds is added to the inflow. A storage element in GoldSim is used to calculate the change in storage given the inflows and out-flows. GoldSim uses the following reservoir routing equation to calculate change in storage:

)()( tOtIS �� )(2

)()(2)( 2121

12 tOOtIISS ��

� �

��

� �

�� (1)

Where S = Storage, I = Inflow, O = Outflow, and t = time.



FIGURE 8 Existing Conditions Model Schematic

Figure 9 illustrates Alpha Pond model logic as an example of how the mass balance of each pond is calculated. “AP” is the storage element that simulates change in storage volume (for Alpha Pond). “Qin” is the sum of precipitation and controlled inflows to the pond, and “Qout” is a sum of evaporation and irrigation demands that pull water from the pond.

The pond operation rules at Meadow Lane and Delta Ponds are similar to those of the other ponds except that these ponds may be drained by discharging to the Laguna or by sending water back into the system to meet demands. For the existing conditions model, discharge is calculated as a percentage of Russian River flow. Discharge rates in Meadow Lane and Delta Ponds are controlled by meeting target volumes in the respective ponds at different times of the year. Discharge rules and criteria become more complex in the future conditions model.



FIGURE 9 Typical Pond Mass Balance Flow Diagram

Existing Pond Operations The following discussion summarizes the status and current operational parameters for each pond in the Subregional System. Table 2 summarizes the basic operating parameters for each pond in the system.

GalloThis pond is currently a one-way pond, receiving inflow from the Rohnert Park Pump Station. Flow cannot be returned to the system from this pond. The piping could potentially be modified to turn this into a two-way pond, benefiting the overall system. The volume of this pond is not counted as part of total system storage. The total pond capacity is estimated to be up to 90 MG, but the maximum usable capacity is equal to the amount that is supplied to irrigation (approximately 60 MG), since Gallo is currently operating as a one-way pond.



TABLE 2Summary of Pond Operating Parameters – Initial Conditions IRWP Seasonal Storage Project – Water Reuse System Storage Model

PondTwo-way Pond?

c

Dead Storage Volume

(MG)

MaximumOperating Volume

b

(MG)

Emergency Overflow Volume

(MG)

MaximumFill/Drain Rate

(mgd)

Alpha no 5 31 37 5 Ambrosini no 5 18 24 4 Browna no 30b 128 145 10 Delta yes 20 572 632 25d

Kelly no 2 23 29 7 Lafranconi no 3 5 6 1 Meadow Lane yes 13 564 600 N/A Place to Play no 10 20 27 1.5 West College no 10 75 106 20 Total 98 1,436 1,606

Gallo no 5 90 100 7 Total w/Gallo 103 1,526 1,706

aBrown Pond dead storage can drop below 30 MG during non-irrigation season. bMaximum operating volume is defined as 2 feet below the overflow level at all ponds except for Meadow Lane Pond, where it is 1.5 feet below the overflow at C and D Ponds and equal to the overflow level at B Pond. cThis means that the pond is capable of a two-way filling and draining operation rather than just a one-way filling operation, which does not have the ability to drain water back into the main supply system. dThe fill rate for Delta Pond includes flow only from Meadow Lane Pond

BrownThis pond is currently a one-way pond, which means water flows into this pond from the existing recycled water system pipeline (main supply system), but water from the pond cannot return to the same pipeline system. This pond is filled during April with a target fill date of May 1. Throughout summer, this pond is slowly filled as-needed for irrigators connected to this pond, which include both City and private demands. The current initial fill rate is 15 mgd. Typically, about 10 MG is added twice per summer to this pond after initial filling. Currently, this pond cannot be filled to its design capacity because when the water level in the pond exceeds the ground level at the onfarm pump station, water leaks around the base of the pump station. If the pump station was elevated above the maximum design water level of Brown Pond, 30 to 35 MG could be added to the usable capacity of the pond. An additional 30 MG of dead storage exists in the bottom of this pond because, if the water level is drawn down farther, private irrigators would be cut off from supply. However, the pond could be completely pumped out in the off season. Mechanical/structural improve-ments to the onfarm pump station at this pond could increase the maximum operating volume to 160 MG.



AlphaThere are two ponds at Alpha that were simulated as one pond in the SPM. An automated control valve opens to fill this pond twice per year (typically), with the first filling occurring by May 1.

Meadow Lane For the purposes of this model, the storage volumes for Ponds B, C, and D were simulated as a single pond. Pond A acts as a wet well for the pump station, with a storage volume too small to have significant impact on the overall operations of the system. Ponds B, C, and D all interact with each other as independent facilities, but will be combined to simplify the SPM. The operating target for filling Ponds C and D is 530 MG, which is 18 inches below the overflows. Pond B overflows into Pond C; therefore, a maximum operating level at Pond B is unnecessary.

LafranconiThis is a relatively small pond that is typically filled three times per year (filled monthly as it is used for irrigation). Fill time is less than 1day.

KellyThis pond is also known as Kelly #1 Pond. Kelly #2 Pond was converted to a wetlands, which does not hold storage that benefits the system. Currently, Kelly #1 Pond is not filled to maximum design capacity of 25 MG because of a bank failure. If the bank around the pond was fixed, 10 MG could be added. A valve is used to fill the pond at a rate of about 2 mgd during the irrigation season.

DeltaDelta Pond is typically filled by May 15. Currently, the water is used to supply the West College system, including areas north and east of Delta Pond and the areas served by the North Pump Station. Sometimes, late in the irrigation season, some users just to the south of Delta Pond will be served from Delta Pond. The goal, late in the irrigation season, is to empty Delta and Meadow Lane Ponds simultaneously. For example, if the Delta Pond water level is significantly higher than that of Meadow Lane Pond in August, water from Delta Pond would be sent southward to supply demands that would have been supplied by Meadow Lane Pond. In this example, Delta Pond could be drained at a faster rate than Meadow Lane Pond for a period of time so that the volumes of the two ponds could come closer to equilibrium. Any water transferred from SCWA is prevented from entering Delta Pond (for water quality reasons) as it continues east into Zone 4 (the West College system). SCWA transfers water from its Oceanview Pond, which can have up to 90 or 100 MG available. The water is transferred in July and August. The transfer in 2006 was 60 to 70 MG, and the rate was about 1.5 mgd. The transfer from SCWA is not considered to be a reliable, long-term supply and is, therefore, not included in the model simulations.

AmbrosiniThis pond fills in less than 1 day, and an automatic valve actuator is used to maintain the water level in this pond. The valve closes when the volume reaches 17 MG, and opens when



it reaches 5 MG. The normal operating range of this pond is 9 to 14 MG. Four users draw water from this pond for irrigation.

Place to Play (Old 1A) Historically, these ponds have been referred to as Ponds 1A, 1B, and 1C. Ponds 1B and 1C are no longer used. Pond 1A is planned to become part of a City park (called Place to Play) by summer 2007. See Table 2 for operating parameters.

West College (Pond 2) West College Pond consists of Ponds 1 and 2. Pond 1 is no longer used. The level in Pond 2 “floats” on the system and is used as a buffer for peak demands in Zones 4 and 5. When demand in this area is low, there is positive flow into the pond. When demand is high, water will flow out of the pond into the system. The pond is drained at the end of the irrigation season. Water is fed to this pond from Delta Pond, but can also be supplied from Meadow Lane Pond.

Storage Pond Rule Curves For the existing conditions model, each pond is operated based on a target storage rule curve that prescribes storage volumes as a function of time of year based on existing operational logic. The basic logic for the operation of all ponds is the same except for individual fill rates and timing. The basic logic for pond operations (except for Meadow Lane and Delta Ponds) is described below.

Starting on October 1 of each year, target pond storage is maintained at or near minimum storage until the fill period begins (usually occurring between the months of March through May. Pond filling is typically short in duration and high in flow rate so that the pond can fill completely in anticipation of irrigation demands through the summer. The filling stops when a target pond volume is reached. Target pond volumes for filling the ponds are listed in Table 2, under “Maximum Operating Volume.”

When the simulated volume of the pond reaches the Maximum Operating Volume, the initial high inflow rate is reduced and the model switches to a sustaining inflow rate, which is intended to maintain approximately the same pond volume through about the end of July. After July, irrigation demands begin to decrease, so the model switches to a “drain period,” which refers to a volume slightly higher than the year-end minimum target volume. The minimum target volume is the dead storage level of the pond shown in Table 2. In the existing conditions model, there are actually no mechanisms to physically drain one-way ponds back into the main supply system. However, the ponds are inherently drained to an extent by supplying irrigation demands. Meadow Lane, Delta, and West College Ponds are two-way ponds and are able to drain back into the main supply system to reduce pond volume to minimum pool by the end of the irrigation season. Figure 10 shows how the storage volume in Brown Pond (a typical one-directional fill pond) rises early in spring, sustains through summer, and drops back to just above minimum storage in late summer.



FIGURE 10 Maximum Operating Volume in Brown Pond (Oct 2003 – Sept 2006)

Existing Demands Figure 11 is a plot of actual recorded irrigation deliveries and Geysers flows between October 2003 and September 2006. The “Pond Demands” line represents demands that pull directly from ponds and the “Zone Demands” line represents zone demands (Zones 1 through 5 and Rohnert Park). The irrigation deliveries data were provided in monthly time-steps, and the Geysers flows were provided in daily time-steps.

FIGURE 11

Irrigation Deliveries and Geysers Flows

Verification of Results Results from the existing conditions model were compared against historical pond level records and discharge rates. Figure 12 is a graph of total system storage volumes compared with recorded values for the 3 years of simulation. Also shown on this graph are minimum and maximum storage rule curves that help the operators make decisions regarding desired storage volume levels at different times of the year.



FIGURE 12 Simulated Total Pond Storage Volume Compared with Recorded Volume As shown on Figure 12, the simulated storage volume closely matches recorded values in 2005 and 2006, but deviates from the observed storage volume in 2004. The difference in storage volume in year 2004 may be the result of differences in the operations strategies in each of the 3 years of record. Specifically, the actual total system storage volume in late 2003 was allowed to rise to a higher volume than the total system storage in late 2004 and 2006. Another difference is that in January 2004, system storage was only reduced to about 600 MG, the volume in January 2005 was reduced to 770 MG, and volume in January 2006 was reduced to 400 MG. These changes in operation are likely the result of real-time operations in response to rainfall events or in anticipation of forecasted high rainfall events. The existing conditions simulation does not reflect these real-time changes in operations because the model logic is based on general system rules designed to approximate operations.

A comparison of actual recorded discharge with simulated discharge was evaluated during verification of the existing conditions model (Figure 13). Discharge rules were developed to mimic actual discharge timing and flow rates. Initially, the model was set to begin discharg-ing when the total storage volume reached specific target values. These target values were developed by analyzing the actual recorded storage volume as compared with actual recorded discharge rates for the 3 years of actual operation. Total storage volume target values were estimated and allowed to change throughout the winter season.

These target values were used in the model to simulate discharge rates that depended on total system volume. For example, on October 15 of each year, discharge would begin if the storage pond volume of Delta Pond exceeded 300 MG; on January 1 of each year, discharge would begin if storage pond volume of Delta Pond exceeded 400 MG; and on March 1 of each year, discharge would begin if Delta Pond storage exceeded 500 MG. Based on actual recorded discharge rates, discharge rates appeared to follow this pattern. However, it was also found that discharge rates on January 1 of each year varied significantly. These changes in operation are attributed to previously experienced (and anticipations of future) variations in winter rainfall patterns. An attempt was made to mimic this change of operation in the



existing conditions model based on analysis completed with the WBM, wherein cumulative Russian River flows at the Hacienda Gage between October 1 and January 1 of each year were tracked and discharge managed accordingly. If, by January 1, the cumulative volume of flow in Russian River exceeded approximately 600,000 acre-feet (AF), discharge would begin when Delta Pond exceeded 200 MG instead of 400 MG.

FIGURE 13 Simulated Discharge Compared with Recorded Discharge Because of inconsistencies in the observed data, there are some differences between the simulated storage volumes and the observed storage values. The complex operational scheme used in the existing conditions model helped to simulate the amount of actual recorded discharge, but some real-time decisions made by the pond operators are difficult to capture within the model’s generalized logic.

Summary of Model Comparison of Existing System The above simulation was performed to demonstrate that the model was capable of simulating existing operational decisions reasonably well. This was accomplished by the following steps:

� Comparison of the overall mass balance � Comparison of simulated to actual pond volumes � Comparison of simulated and actual discharge volumes � Confirmation that the model achieves closure from a mass balance perspective

The verification demonstrates that the model is adequate for planning purposes and provides a reasonable simulation of existing operations.

Future Conditions Model Formulation General Approach The existing conditions model was modified to incorporate the capability to simulate the operation of alternative future conditions. This includes simulation of proposed storage site



locations and pond volumes, changes in operations, increased demands/reuse, changes in receiving water quality constraints, and increased Laguna Plant production. To simulate the ponds, dynamic storage rule curves were developed to control and balance simulated pond inflows, outflows, and discharges. The rule curves provide a continuous target storage level for each pond that triggers when to begin storing water, control discharge quantity and timing, and allocate water to irrigation and other demands.

The future conditions model was used to evaluate multiple demand and storage scenarios. These scenarios included 6 different future pond configurations (one of which includes no increase to overall storage capacity), and five future demand levels, which were simulated for five historical years (from the WBM) representing a range of critical dry to wet hydro-logic conditions. The future conditions model simulates 365 days starting on October 1 and ending on September 30 for a given time series of water production and demand conditions.

Data Collection The data used for future scenario runs are listed in Table 3. The source of the data was the original WBM, Randy Piazza, and the California Irrigation Management Information System (CIMIS) website. To simulate future scenarios, the system representation in the future conditions model must be as consistent as possible with the data assumptions used in the WBM. TABLE 3 List of Data Obtained for the Future Conditions Model IRWP Seasonal Storage Project – Water Reuse System Storage Model

Type Description Source Time-Step File Name

Total Storage volume (used only for comparison) WBM Daily 5-year types.xls Stage-volume curves for each pond Randy Piazza N/A Pond reading chart.xls

Storage

Summary of operational ranges of storage at individual ponds

Randy Piazza N/A SR5.xls

Geysers flow data WBM Daily 5-year types.xls Tier priorities for demands N/A SR5.xls Urban demand patterns WBM Monthly SR5.xls

Demands

Laguna T1 & T2 and Rohnert Park demand patterns WBM, Randy Piazza

Monthly Irrigation_Summary.xls

River discharge (for comparison only) WBM Daily 5-year types.xls Russian River flows at Guerneville WBM Daily 5-year types.xls Laguna Plant flows near Delta Pond WBM Daily 5-year types.xls Laguna Plant water surface elevation near Delta Pond

WBM Daily 5-year types.xls

River and Discharge

Russian River Flows at Hacienda Gage WBM Daily 5-year types.xls Climate Precipitation and lake evaporation CIMIS Daily SR5.xls Inflow Laguna Plant effluent flow data WBM Daily 5-year types.xls Figure 14 shows the layout of ponds in the future conditions model, which includes the potential Petaluma Hill Road site and urban demands.



FIGURE 14 Future Conditions Model Schematic Petaluma Hill Road Pond For the scenarios that include adding Petaluma Hill Road (PHR) Pond, water will be sent from the EB pumps at Meadow Lane Complex to the new pond, where water will be distributed to irrigation demands, including those of South Santa Rosa Urban Reuse and additional Rohnert Park Reuse. If PHR Pond needs to be drained, and there is not enough demand to drain the pond, excess water in the pond will be returned to other demands of the Rohnert Park system and will reduce the flow through the Rohnert Park Pump Station and the EB pumps.

Future DemandsDemands in the future conditions model are categorized into two tiers and are separated into six priorities within these tiers. Table 4 summarizes how these demands are prioritized.



Demands are reduced if the total storage is insufficient to meet the full demands through the end of the irrigation season. Lowest priority demands are reduced first; subsequently, the next higher priority demand is reduced, if needed. The next higher priority demand is only reduced if the lower priority demand has been reduced to zero. Laguna Tier 2 demands are treated differently because reductions to these demands affect harvesting operations and, therefore, must be turned off for the remainder of the season if they are to be reduced. Baseline demands are outlined herein based on potential future scenarios, but can be modified to explore various levels and priorities of reuse.

TABLE 4 Summary of Demand Priorities IRWP Seasonal Storage Project – Water Reuse System Storage Model

Demand Name Tier Level Priority

Geysers Tier 1 1 1

Urban Tier 1 1 2

Laguna Tier 1 1 3

North County Tier 1 1 4

Geysers Tier 2 2 5

Laguna Tier 2 2 6

Note:

Geysers Tier 1, Laguna Tier 1, and Laguna Tier 2 are existing demands, while the others are possible future demands.

Urban and Geysers demand patterns were obtained directly from the WBM. All agricultural demand patterns (included in Laguna Tier 1, North County Tier 1, and Laguna Tier 2) in the model are based on a demand pattern developed from actual recorded data for the existing Laguna Tier 1 and 2 demands for 2003 through 2006. The average of these 3 years of record was used to develop the agricultural demand pattern, and the total annual volume of demand was obtained from the TM, Laguna Agricultural Demands – Tier 1 and 2 Demand Levels, November 2006. Agricultural demands in the WBM typically do not begin until at least May 1 of each water year. For the future conditions model to be consistent with the WBM, the historical agricultural demands were modified to begin May 1 and use the same springtime demand reductions as the WBM. Figure 15 is a graph of Zone 1, Tier 1 agricultural demands used in the future conditions model. Reductions in the spring/early summer occur as a result of increased precipitation.



FIGURE 15 Example of Agricultural Demands for Different Years Total annual demands used for various scenarios analyzed in the future conditions model are summarized in Table 5.

TABLE 5Demand Scenario SummaryIRWP Seasonal Storage Project – Water Reuse System Storage Model

Demands in (MG) for Each Demand Scenario

Demand Scenario 1b 2 3 4 5

Conservation 0 300 300 300 300

GeysersT1 4,000 4,000 4,000 4,000 4,400

Urban T1 (North) 0 500 500 500 500

Urban T1 (South) 0 500 700 700 500

Laguna T1 1,720 1,720 1,720 1,720 1,720

North County T1 0 100 100 100 400

Geysers T2 0 700 700 2,930a 0

Laguna T2 720 720 720 720 720

Total 6,440 8,540 8,740 10,970 8,540

aDepends on hydrologic year and how much storage is available. Geysers Tier 2 demand goal = 19 mgd – Geysers Tier 1 flow rate, but only to the extent that supply is available. bDemand scenario 1 represents existing conditions.

Geysers Tier 1 Demand The Geysers Tier 1 demand is the highest priority demand in the system and typically fluctuates only slightly through the year. This demand is supplied through the Geysers Pump Station and Pipeline. Figure 16 is a plot of a typical monthly flow pattern for Geysers Tier 1 demands, which is specified in the existing agreement with Calpine.



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FIGURE 16 Typical Demand Pattern for Geysers Tier 1 Demand (Driest Year) Urban Demand The urban demand is the second highest priority demand in the system and typically continues through the year with minimal demands in the winter and significantly higher demands through the summer. Figure 17 is a plot of a typical monthly demand pattern for the Urban Reuse System, which is based on historical urban reuse demand patterns.

FIGURE 17 Typical Demand Pattern for Urban Demand (Driest Year) Laguna Tier 1 Demand The Laguna Tier 1 demand is the third highest priority demand in the system and typically does not start until May 1 each year. This demand is typically supplied through the EB Pump Station and from various ponds throughout the system. The pattern for this demand is based on historical agricultural irrigation demands in the Laguna system. Figure 18 is a plot of a typical monthly demand pattern for Laguna Tier 1.



FIGURE 18 Typical Demand Pattern for Laguna Tier 1 Demand (Driest Year) Rohnert Park demands are included in the same tier priority as Laguna Tier 1 demands, but are characterized by a different demand pattern. The Rohnert Park demand pattern is based on the average demands of the last 3 years of recorded Rohnert Park water use data. Figure 19 is a graph showing the Rohnert Park demand pattern used for Rohnert Park high-pressure demands.

FIGURE 19 Typical Demand Pattern for Rohnert Park Demand (Driest Year) North County Demand The North County demand is the fourth highest priority demand in the system and typically does not start until May 1 each year. The monthly pattern for this demand is based on the demand pattern used for Laguna Tier 1 demands. This demand is supplied through the Geysers Pump Station and Pipeline. Figure 20 is a plot of a typical monthly pattern for North County demands.



FIGURE 20 Typical Demand Pattern for North County Demand (Driest Year) Geysers Tier 2 Demand The Geysers Tier 2 demand is the fifth priority demand in the system and typically fluctuates only slightly through the year. This demand is supplied through the Geysers Pump Station and Pipeline. Typical monthly flow for Geysers Tier 2 is constant at 1.9 mgd (except for Demand Scenario 4, where it increases to as much as 7 to 8 mgd).

Laguna Tier 2 Demand The Laguna Tier 2 demand is the lowest priority demand in the system and typically does not start until May 1 each year. This demand is usually supplied through the EB Pump Station and from various ponds throughout the system. Figure 21 is a plot of a typical monthly demand pattern for Laguna Tier 2.

FIGURE 21 Typical Demand Pattern for Laguna Tier 2 Demand (Driest Year) Demands are physically distributed through the system into categories as shown in Table 6. Spatial distribution of demands is based on records obtained from Randy Piazza. These



records are categorized into Demand Zones 1 through 5, Rohnert Park, and Tier 2 demands at Alpha, Brown, and Kelly Ponds.

TABLE 6 Spatial Demand Distribution IRW P Seasonal Storage Project – Water Reuse System Storage Model

Zone or Pond Demand Priority

Name

Annual Demand Volume (median year, demand scenario 3)

(MG)

Zone 1 (north of EB pumps) Laguna T1 105

Zone 1 (south of EB pumps) Laguna T1 160

Zone 2 Laguna T1 175


Zone 4 Laguna T1 90


Zone 5 (north of Delta Pond) Laguna T1 201

Rohnert Park Low Pressure Laguna T1 163

Rohnert Park High Pressure Laguna T1 216

North County North County T1 104

Alpha Pond Laguna T2 216

Ambrosini Pond Laguna T1 65

Broun Pond (Tier 1) Laguna T1 52

Brown Pond (Tier 2) Laguna T2 200

Gallo Pond Laguna T1 50

Kelly Pond Laguna T2 304

Lafranconi Pond Laguna T1 86

Place to Play Pond Laguna T1 8

West College Pond Laguna T1 5

West College Pond Urban T1 (North) 500

Rohnert Park System (May include PHR and/or Gallo Ponds)

Urban T1 (South) 700

Geysers Geysers T1 and T2 4,700

Conservation N/A 300

Total 8,745

Five Year Types Used in Future Simulations The future conditions model is run for each of five hydrologic year types for each pond and demand scenario. These five years represent a range of critical dry to wet hydrologic conditions. The data for these five years are part of a larger dataset used in the WBM and include demand patterns, Laguna Plant effluent flow rates, and Russian River flows. Simulation results from the WBM, such as total storage volume and discharge flows, were used for model verification to check the consistency of the results between the future



conditions model and the WBM. Table 7 shows the average Laguna Plant flow and Russian River flow for each of these five years.

TABLE 7 Five Year Types Used in Future Conditions Simulations IRWP Seasonal Storage Project – Water Reuse System Storage Model

Year Type Year of Source

Data

Average Laguna Plant Flow

(mgd)

Average Russian River Flow

(cfs)

Driest Year 1977 25.1 48

Dry Year 1972 26.7 500

Median Year 1917 29.3 1,191

Wet Year 1914 31.8 2,718

Wettest Year 1983 34.5 3,884

The assumed future base flow (dry weather flow) from Laguna Plant is 25.1 mgd after accounting for 300 MG of conservation, which is equal to a flow rate of approximately 0.8 mgd. During rain events, the Laguna Plant production rate increases above the base flow as shown on the graph of production rates for the five years used in the model (Figure 22).

FIGURE 22 Future Laguna Plant Production for the Five Years Russian River flows for the five years are shown on Figure 23. This graph shows that the median year flow was greater than wet year flow in the spring.



FIGURE 23

Russian River Flow for the Five Years

Dynamic Storage Rule CurvesStorage rule curves are the primary method of controlling storage and discharge from storage. The rule curves used in this model were developed such that Tier 1 demands must be met, while Tier 2 demands are to be supplied only if excess water exists (i.e., in excess of specified operational storage). Storage rule curves are used to manage flows into and out of ponds in the system to maintain desired storage.

The dynamic concept and general shape of the rule curves are derived from the curves used in the WBM. The general shape of the curve is shown on Figure 24. The volume under the initial portion of the rule curve stays at minimum total system dead storage to provide discharge management to meet temperature objectives or minimize discharge violations. The peak of the curve, which occurs between May 1 and June 1, is a function of Tier 1 demands that must be met through the end of September. To store enough water to meet potential future demands and attain the target storage level on June 1, the rule curve must start to rise early in the spring. However, this timing depends on the year-to-date hydrology and annual Tier 1 demand level. In wet years (as indicated by November through March hydrology), the rising limb of the rule curve is steeper, and might not start rising until April 1. In a dry year (as indicated by year-to-date hydrology), the rising limb of the rule curve will be flatter and could start rising as early as March 1 or even February 1, depending on the annual Tier 1 demands being imposed on the system.



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Example Total System Storage Rule Curve Three different types of rule curve sets are used, depending on the demand scenario in the model. Each of these sets of curves allow for changes in the start date when storage begins to fill (i.e., post-fill date). Table 8 summarizes the peak volume required to meet Tier 1 demands.

TABLE 8 Minimum Tier 1 Demand Storage Requirements IRWP Seasonal Storage Project – Water Reuse System Storage Model

Demand Scenario Minimum Storage Requirement to Meet Tier 1 Demands

2 Minimum June 1 storage = 1,000 MG

3 and 4 Minimum June 1 storage = 1,200 MG

5 Minimum June 1 storage = 1,400 MG

The logic used to create the sets of rule curves was based on available Russian River flow and Laguna Plant production data provided for the five years and the various demand options. A minimum total system-wide dead storage volume of 100 MG is assumed for all model runs. This is the target volume in the late winter or early spring before the storage fill date occurs; however, storage may increase above minimum pool in response to wet weather events. The minimum June 1 storage shown in Table was determined as the approximate amount required to serve all Tier 1 demands through September with a buffer of 100 MG. This buffer is used to ensure that demands are met and storage does not fall below the minimum storage in September. The different hydrologies of the five water years affects the ability to meet the June 1 storage requirement. For example, in a dry year, initiation of increasing storage from dead storage level must begin at an earlier date than a wet year to meet the June 1 requirement.

Based on WBM analyses using flow through February as an indicator of hydrologic year type, the decision process in the model allows the rule curve to shift based on the current



hydrology. Figure 25 presents a probability distribution of 90 years of Russian River flow data to show the cumulative volume between October 1 and February 28.

FIGURE 25 Cumulative Flows in Russian River at Hacienda Gage (Oct – Feb) It was assumed that if the cumulative flow volume in Russian River at Hacienda Gage exceeded the value shown on the graph at the 80 percent probability, or was above approxi-mately 400,000 AF by March 1, the year was considered to be a normal to wet year on March 1. If by March 1, the cumulative flow was found to be less than 400,000 AF (or greater than 80 percent probability), the year was considered to be a drier than normal year.

The decision process outlined above is used for all demand scenarios to determine the point of initializing a storage increase from dead pool on March 1. The date that this increase in storage begins is shifted in the model based on whether the year is considered dry by March 1.

For demand scenarios 3 and 4, it was necessary to add another decision point at February 1 to ensure that the minimum storage requirement of 1,200 MG is achieved by June 1 for all water years. In drier years, it might not be possible to meet the required 1,200 MG by June 1 if the determination of whether or not it was a dry year was not made until March 1. To make the decision on February 1, the same process was used to determine a dry year (using 80 percent probability exceedance criteria), but using a dataset for October through January instead of October through February. See Figure 26 for a graph of probability of exceedance for the October through January timeframe.



FIGURE 26 Cumulative Flows in Russian River at Hacienda Gage (Oct – Jan) For demand scenarios 3 and 4, it was assumed that if the cumulative flow volume in Russian River at Hacienda Gage exceeded the value shown on the graph at the 80 percent probability by February 1, the year was considered to be a normal to wet year. If by February 1 the cumulative flow volume was greater than 80 percent probability, the year was considered to be a drier than normal year.

For demand scenario 5, the minimum storage requirement for June 1 is 1,400 MG. To ensure that this storage can be obtained under all five water years, storage must begin to accumu-late on February 1. But on March 1, the decision process discussed above was used to determine whether or not the year was dry. If it was found to be a wet to normal year on March 1, the rule curve shifts accordingly on March 1.

Figures 27 through 29 illustrate the decision process and resultant rule curves used to target storage requirements for all water years and the various demand scenarios. The figures illustrate the various permutations that could occur depending on the decisions made on February 1 and March 1.



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FIGURE 27 Demand Scenario 2 – March 1 Decision Only

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FIGURE 28 Demand Scenarios 3 and 4 – February 1 and March 1 Decision



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FIGURE 29 Demand Scenario 5 – March 1 Decision Only

Pond Operations Logic Pond operations logic was developed for all the ponds (future and existing) within the Subregional System. The logic is used to provide a means to simulate water that is moved from Laguna Plant to various ponds, then supplied to areas for irrigation or discharged to the Laguna, and to maintain proportionate pond volumes given certain constraints of each pond.

Meadow Lane Pond to Delta Pond Flow Logic The operational rules to control flow from Meadow Lane Pond to Delta Pond are as follows:

1. Pumping capacity at EB Pump Station is 25 mgd minus any additional flows in the main pipeline between Brown Pond and Delta Pond.

2. Maintain a volume in Meadow Lane Pond that is 30 to 40 MG less than that of Delta Pond to provide a storage buffer in Meadow Lane Pond while Laguna Plant production rates continue to fluctuate through the wet season.

3. Decrease pumping to Delta Pond if Meadow Lane Pond volume drops to 5 MG or less.

4. Increase pumping to Delta Pond by a factor of 2 (up to 25 mgd) if the storage volume in Meadow Lane Pond approaches the maximum operating volume.

5. If Delta Pond volume is more than 40 MG higher than Meadow Lane Pond in August and September, release water from Delta Pond back into the Meadow Lane Pond system to drain storage to help meet the minimum fall carryover target.

This logic is used for all scenarios, and the goal is to maintain a balanced operation between Meadow Lane and Delta Ponds, as shown for pond scenario 6, demand scenario 3 on Figure 30.



FIGURE 30 Meadow Lane and Delta Pond Storage and Flow Rate to and from the Ponds Individual Pond Rule Curves The pond logic used for all ponds (except Lafranconi, Ambrosini, and Place to Play) in the future conditions model follows a rule curve that is the same shape as the overall system rule curve described in the section, Dynamic Storage Rule Curves. The rule curve used for each pond is a scaled-down version of the overall system rule curve. These curves are calculated as a proportion of total system storage equal to the difference in maximum storage volume of the individual pond divided by the total maximum system storage volume as shown in the following equation:

Pond Rule Curve = (Pond Max Volume / Total System Volume) * Total System Rule Curve (2)

Where Pond Max Volume is the maximum operating volume for each pond, and Total System Volume is the total combined maximum operating volumes of all the ponds.

The future conditions model includes the ability to drain some ponds back into the system, and to meet demands from the pond. This means that the ponds are capable of a two-way filling and draining operation rather than just a one-way filling operation. Refer to Table 9 for a summary of ponds that allow proposed two-way operations in the future conditions SPM. Refer to Table 2 for a summary of pond operational volumes (including dead storage, maximum operating volume, and emergency overflow volumes) and fill/drain rates used for the initial conditions of the model. The values shown in Table 2 reflect initial conditions in the future conditions model and do not show changes in storage volumes for other pond scenarios that were analyzed. For a comparison of the storage volumes of each pond for all scenarios evaluated, refer to Table 11.



TABLE 9 Summary of Ponds that Allow Two-way Drain-fill Operation IRWP Seasonal Storage Project – Water Reuse System Storage Model

Pond Two-way Pond?

Alpha yes

Ambrosini no

Brown yes

Delta Yes

Kelly Yes

Lafranconi No

Meadow Lane Yes

Place to Play No

West College Yes

PHR Yes

Gallo No

The fill and drain rates used for PHR were estimated by determining the rate required to fill the pond to the maximum operating volume, if needed, and to drain the pond before October 1.

In the future conditions model, simulated pond volumes will generally follow the rule curve and stay within the bounds of dead storage and maximum operating volume. When total system storage volume is high, pond operational rules allow storage to slightly exceed the maximum operating volume when discharge is limited, but storage is never allowed to exceed the emergency overflow volume. If any pond volume exceeds the emergency volume or drops below 0.0 MG, the user is notified during the simulation, and a warning message is sent to the results file. In model runs of the future conditions SPM, appropriate iterative adjustments were made to the model to prevent these occurrences in the simulations.

As shown on Figure 31, inflows to and outflows from the pond are controlled so that the simulated volume of the pond follows the rule curve for Alpha Pond. The controls in the model will cause water to be released from Meadow Lane Pond and Delta Pond for storage in other ponds if Meadow Lane Pond and Delta Pond storage is within 200 to 300 MG below their maximum operating levels.



FIGURE 31 Alpha Pond Volume with Inflows and Outflows (Wet Year) As shown on Figure 32, water is sent to Alpha Pond in May when discharge is no longer possible at Meadow Lane Pond or Delta Pond. Later in the summer when irrigation demands are high, this water can be drained from Alpha Pond to serve demands in other ponds and areas.

FIGURE 32 Alpha Pond Volume with Inflows and Outflows (Wettest Year) Water transfers from Meadow Lane Pond or Delta Pond to other ponds in the system may be limited when smaller ponds become too full. To limit these flows, a lookup table was used that is based on storage levels and emergency pond storage levels. The lookup table creates a ratio between 0 and 1, with 0 indicating that this pond is full, and 1 indicating that it is not full.



Discharge Controls Discharge can occur from Meadow Lane Pond and Delta Pond subject to certain rules and limitations, which include seasonal timing, physical limitations, dilution requirements, temperature criteria, and pond capacity.

Discharge rates from Meadow Lane Pond and Delta Pond are controlled using the overall storage rule curves for each pond. Figure 33 shows that discharge is triggered when the total storage volume rises above the rule curve. The magnitude of discharge increases as the total storage volume continues to rise above the rule curve.

FIGURE 33 Total Discharge vs. Total Storage Volume Discharge from Delta Pond To avoid impacts of discharge, discharge from Delta Pond has a higher priority than discharge from Meadow Lane Pond, which causes Delta Pond discharge to begin before Meadow Lane Pond discharge, and to discharge more volume than at Meadow Lane Pond. The following factors are used at Delta Pond to control discharge:

1. Discharge Season: Discharge is allowed beginning October 1 and ending May 14.

2. Hydraulic Capacity Limitation: Discharge at Delta Pond is sometimes restricted hydraulically by the difference in water levels in Delta Pond and in the Laguna. The following logic is used to calculate the hydraulic capacity to discharge from Delta Pond:

Discharge occurs when the water surface (WS) elevation in Delta Pond exceeds the WS elevation in the Laguna, and the following equation is used to calculate discharge:

QDP = 21 * ( ElevDP – ElevL_DP) ^ 0.5 (3)

Where QDP = discharge from Delta Pond, ElevL_DP = WS elevation in the Laguna at Delta Pond, and ElevDP = WS elevation in Delta Pond.

Backflow from the Laguna to Delta Pond could occur, and is calculated using the following logic:

a. Backflow occurs when WS elevation in the Laguna exceeds the WS elevation in Delta Pond.



b. Russian River flow at Hacienda Gage exceeds 15,000 cfs.

c. Backflow rate into Delta Pond is calculated as follows:

QDP = 21 * ( ElevL_DP – ElevDP) ^ 0.5 (4)

Where QDP = backflow rate into Delta Pond, ElevL_DP = WS elevation in Laguna at Delta Pond, ElevDP = WS elevation in Delta Pond.

3. Total System Discharge is Limited to 5 Percent of Russian River Flow at Hacienda Gage: The sum of the total discharge from Delta Pond and Meadow Lane Pond is limited to an equivalent flow equal to 5 percent of the flow in the Russian River at the Hacienda Gage. The 5 percent rule is applied to Delta Pond as follows:

If simulated total system storage minus the desired storage value from the system rule curve is less than 50 MG, then discharge is 0 mgd. If total system storage minus the system rule curve is between 50 MG and 70 MG, then discharge ramps up from 0 to 4.99 percent of Russian River flows. If the system storage minus the system rule curve is between 70 MG and 1,300 MG, then the discharge will be 5 percent. If the variance is greater than 1,300 MG, then the discharge will be greater than 5 percent. This forces the model to restrict discharges greater than 5 percent to extreme circumstances in which the total storage is approaching maximum capacity.

4. Discharge is Limited by Biological Temperature Criteria: These criteria (described in the Laguna Water Temperature Criteria section below) will control discharge from Delta Pond unless the volume at Delta Pond rises to within 50 MG of its maximum operating volume level. The temperature criteria are further discussed in the following section.

5. Emergency Discharge: If the storage volume of the pond exceeds the emergency volume, the model automatically allows up to 100 mgd discharge, regardless of other limitations.

Discharge from Meadow Lane Pond The basic discharge logic at Meadow Lane Pond is the same as that of Delta Pond except there is no hydraulic backwater limitation. The following factors are used to control discharge at Meadow Lane Pond:

1. Discharge Season: Discharge is allowed beginning October 1 and ending May 14.

2. Hydraulic Capacity Limitation: Discharge from Meadow Lane Pond is limited to a maximum of 50 mgd.

3. Discharge Limited to 5 Percent of Russian River Flow: Combined discharge at Meadow Lane and Delta Ponds is limited to an equivalent flow equal to 5 percent of the flow in the Russian River at the Hacienda Gage. The 5 percent rule is applied in the model as follows:

If the simulated storage in Meadow Lane Pond minus the desired storage value from the Meadow Lane Pond rule curve is less than 210 MG, then discharge is 0 mgd. If Meadow Lane Pond volume minus the Meadow Lane Pond rule curve is between 210 MG and 500 MG, then discharge ramps up so the combined discharge of Meadowlane and Delta



Ponds will not exceed 5 percent of total Russian River flow. If Meadow Lane Pond volume minus the Meadow Lane Pond rule curve is greater than 500 MG, then the combined discharge will be greater than 5 percent. If the variance is greater than 1,300 MG, then the combined discharge will be greater than 5 percent. This logic forces the model to restrict combined discharges greater than 5 percent to extreme circum-stances in which the Meadow Lane Pond storage is approaching maximum capacity.

Water may be pumped from Meadow Lane Pond to Delta Pond through the EB Pump Station according to the pond operations logic discussed in the Pond Operations Logic section of this TM. This transfer reduces the need to discharge from Meadow Lane Pond because it reduces the volume of storage to less than 210 MG above the rule curve during the driest and dry years.

4. Discharge is Limited by Biological Temperature Criteria: These criteria will control the discharge from Meadow Lane Pond unless the volume in the pond rises above the emergency overflow volume level. The temperature criteria are further discussed in the following section.

5. Emergency Discharge: If the storage volume of the pond exceeds the emergency volume, then the model automatically allows up to 100 mgd discharge, regardless of other limitations.

As shown on Figure 34, the discharge from Delta Pond occurs more frequently than from Meadow Lane Pond. This figure shows model simulation results for pond scenario 6, demand scenario 2, for a median water year.

FIGURE 34 Meadow Lane Discharge vs. Delta Pond Discharge

Laguna Water Temperature CriteriaThe Laguna water temperature limitations on discharge are based on biological receiving water temperature criteria, which were provided by Merritt Smith Consulting. Figure 35 is a graph of the monthly biological temperature criteria. To assess temperature criteria in the SPM, a simplified set of thermal criteria were developed based on existing discharge permit



conditions. Although existing permit language has detailed requirements on allowable increases based on receiving water temperatures, for planning level analysis, a range of representative values based on time of year and salmon life stage were developed as screening criteria (M. Fawcett, pers. comm.) (Figure 35)

FIGURE 35 Biological Temperature Criteria

A series of mass balance equations calculate the change in temperature in the Laguna as reuse water is discharged from Meadow Lane and Delta Ponds. Figure 36 is a schematic diagram showing the mass balance calculated at each point in the Laguna.

The flow in the Laguna at point A (QA) is input to the model daily, and the flows vary by water year. The assumed Laguna and pond discharge water temperature values at points A, M, and D are input to the model. To calculate the flow and temperature at point B in the Laguna, the following mass balance equations are used.

QB = QA + QM (5)

And

TB = (QA * TA + QM * TM) / QB (6)

QB and TB are flow and temperature calculated at point B in the Laguna.

Some additional contributing flows enter the Laguna between points B and E. This flow contribution is calculated by comparing the known flow at point A and the known flow just upstream of Delta Pond, both of which are provided by Merritt Smith Consulting. This flow contribution between points B and E is referred to as QX. The temperature of QX is assumed to be equal to TA. To calculate the flow and temperature at point E in the Laguna, the following mass balance equations are used:

QE = QB + QX (7)

And

TE = (QB * TB + QX * TX) / QX (8)



FIGURE 36 Schematic of Mass Balance Temperature Equations in Laguna QE and TE are flow and temperature calculated at point E in the Laguna.

Discharge from Delta Pond enters the Laguna between points E and F and the following mass balance equations are used to calculate flow and temperature at point F.

QF = QE + QD (9)



And

TF = (QE * TE + QD * TD) / QF (10)

QF and TF are flow and temperature calculated at point F in the Laguna.

Allowable discharge based on temperature is calculated as the flow rate allowed before discharge causes an increase in the Laguna temperature above the biological criteria by more than 0.5 degree Fahrenheit (°F). The equation for maximum discharge from Meadow Lane Pond is as follows:

Allowable Discharge = QA * (TA – [TBC + 0.5°F]) / ([TBC + 0.5°F] – TM) (11)

The equation for maximum discharge from Delta Pond is as follows:

Allowable Discharge = QE * (TE – [TBC + 0.5 °F]) / ([TBC + 0.5°F] – TD) (12)

TBC is equal to the biological temperature criteria.

These equations calculate the allowable discharge rate that would not increase water temperature in the Laguna above the biological temperature criteria.

The allowable discharge based on temperature is used as a soft constraint at Delta Pond and a hard constraint at Meadow Lane Pond. Delta Pond discharge is constrained to the maximum temperature discharge rate until the volume in Delta Pond comes to within 50 MG of the maximum operating volume. Discharge at Meadow Lane Pond is restricted to temperature-based discharge unless the emergency pond level is reached. Figure 37 shows the water temperature downstream of Delta Pond as compared with the biological criteria.

FIGURE 37 Temperature Downstream of Delta Pond vs. Temperature Criteria

Future Pump Operations The specific assumptions used in the model for each pump station are described below. Table 10 summarizes assumed maximum pump station and pipeline capacities.



Delta Pump Station Delta Pump Station operates according to the rule curve for West College Pond using the methodology described in the section, Individual Pond Logic. The pump station has a capacity of 20 mgd and will shut down if storage in Delta Pond drops below a minimum threshold value.

TABLE 10 Assumed Maximum Operating Pump and Pipeline Capacities IRWP Seasonal Storage Project – Water Reuse System Storage Model

Description Capacity

Pipe from Laguna Plant to Meadow Lane Pond No limit in model

Pipe from EB pumps to as far north as Brown Pond 30 mgd

Pipe from as far north as Brown Pond to Delta Pond 25 mgd

Pipe from Delta Pump Station to West College Pond 20 mgd

Pipe from EB pumps to Rohnert Park System 23 mgd

EB Pump Station 30 mgd

Geysers Pump Station 40 mgd

Rohnert Park Pump Station 23 mgd

Delta Pump Station 20.2 mgd

EB Pump Station The flow at the EB Pump Station is the sum of all the irrigation demands and flows into the ponds north and south of the pump station plus the flows needed to fill Delta Pond. The capacity of the pump station is 30 mgd. The pipeline to Delta Pond is limited to a capacity of 25 mgd, so the pipeline reaches maximum flow capacity before the pump station.

Geysers Pump Station The Geysers Pump Station has a capacity of 40 mgd, and the required pump flow rate is calculated as the sum of Geysers Tiers 1 and 2, and North County demands.

Rohnert Park Pump Station Rohnert Park Pump Station has a capacity of 23 mgd, and the required pump flow rate is calculated as the sum of flow entering Gallo Pond and Rohnert Park high-pressure zone, plus flows to PHR Pond if it is included in the scenario.

Future Conditions Model Results The future conditions model simulates the Subregional System under combinations of different pond size/location alternatives and demand scenarios. Table 11 summarizes the pond scenarios analyzed in the future conditions model and the combinations of demand scenarios simulated under each scenario (shown on bottom row of the table). Shaded entries indicate scenarios with pond improvements/enlargements or incorporation of new ponds to augment existing storage. Scenarios 3, 4, 7, 8, and 9 have been removed because some pond configurations being eliminated from the analysis prior to completion of this TM.

WATER REUSE SYSTEM STORAGE MODEL WATER REUSE SYSTEM STORAGE MODEL


TABLE 11Pond Storage Scenario SummaryIRWP Seasonal Storage Project – Water Reuse System Storage Model

Pond Operating Volumes for Seven Storage Scenarios (MG)

Pond 1 2 5 6 10 11 12

Alpha 30 30 230 230 30 30 30

Ambrosini 18 18 18 18 18 18 18

Brown 128 128 128 378 128 158 558

Delta 572 572 572 572 572 572 572

Gallo 90 90 90 90 90 90 90

Kelly 23 23 23 273 23 503 23

Lafranconi 5 5 5 5 5 5 5

Meadow Lane 564 564 564 564 564 564 564

Place to Play (old 1A) 20 20 20 20 20 20 20

West College 75 75 75 75 75 75 75

PHR 0 0 500 0 500 0 0

Total 1,525 1,525 2,225 2,225 2,025 2,035 1,955

Laguna Plant Base Flow (mgd) 16.5 25.9 25.9 25.9 25.9 25.9 25.9

Demand Scenario(s) Analyzed 1 2-4 2-4 2-5 2-5 2-4 2-4

Note:

Shaded entries represent pond improvements/enlargements or incorporation of new ponds to augment existing storage (refer to “Future Pond Operations” section).

All of the scenario combinations were simulated for each of the five water years. The model results of each scenario combination are automatically exported to a Microsoft Excel file called “SR5.xls” after each scenario run. The summary table showing all of the scenario results is included in Attachment 1 of this TM.

The following conclusions are based on evaluation of the results from the future conditions model:

Location of Future Ponds: Through simulations of all the different pond location scenarios, storage location does not affect the volume of future total system storage capacity needed nor the ability to discharge.

Additional Volume Requirement: The range of additional storage volume required for all of the scenarios run in the future conditions model is between 200 and 650 MG. The additional volume required is assumed to be the peak storage minus the existing maximum operating volume of all the ponds in the system, which is 1,436 MG. As shown in Table 12, for pond Scenario 6, the wettest and driest years require the largest volumes of additional storage. In the driest year, Russian River flows are very low, and discharge to the Laguna is



extremely limited, requiring more storage. In the wettest year, Laguna Plant production is very high during wet weather events, and discharge to the Laguna may be limited by backwater effects from the Russian River. Extra storage needed in the wettest year type over that needed in the driest year type could be avoided or reduced if the discharge capacity under high flow conditions was increased by using a pump station to overcome the backwater limitation. Additional analysis would be required to determine whether additional storage or pumping is more economical. The summary table of results in Attachment 1 shows that the driest and wettest year simulations require the highest additional storage volumes for all of the pond size, location, and demand scenarios.

TABLE 12 Summary of Additional Storage Requirements (MG) – Pond Scenario 6, Demand Scenarios 2 through 5 IRWP Seasonal Storage Project– Water Reuse System Storage Model

Demand Scenario Representative

Year 2 3 4 5

Driest 416 360 0 555

Dry 0 0 0 0

Median 151 276 30 298

Wet 0 0 0 25

Wettest 441 546 203 650

The different demand scenarios also have a direct impact on the additional volume requirement. As shown in Table 12, the additional volume requirement for a median year increases from demand scenario 2 to scenario 3. This increase is because demand scenario 3 includes an additional 200 MG of urban demand, which requires more seasonal storage and raises the storage rule curve by 200 MG in May and June. This higher urban demand forces a reduction in Geysers Tier 2 demand during the month of April when the Laguna Plant production is relatively high. The net effect is that more storage is required under demand scenario 3 in the median year.

The additional storage required for demand scenario 4 is much less than for other demand scenarios because demand scenario 4 includes higher Geysers Tier 2 demands. For example, under the median year, approximately 200 MG of Geysers Tier 2 demand is applied during the month of May in demand scenario 4, which reduces the required peak storage significantly.

River Discharge: The results of the future conditions simulations show that the different demand scenarios have an effect on discharge volume. Table 13 shows that scenarios with higher demands have lower total discharge volumes to the Laguna.



TABLE 13 Summary Total Discharge (MG) – Pond Scenario 6, Demand Scenarios 2 through 5 IRWP Seasonal Storage Project – Water Reuse System Storage Model

Demand Scenario Representative

Year 2 3 4 5

Driest 304 299 243 303

Dry 1,819 1,761 1,130 1,579

Median 2,533 2,381 1,632 2,527

Wet 3,845 3,733 3,006 3,888

Wettest 4,270 4,098 3,324 4,240

Development of Rule Curves: Rule curves based on Tier 1 demands provide a dynamic approach to storage evaluation. As discussed in the Dynamic Storage Rule Curves section of this TM, rule curves were developed according to Tier 1 demands that occur between June 1 and September 30. It was found that this method produced a set of dynamic rule curves that can be applied to all five water years.

Pipe and Pump Capacities: The results of the future conditions model indicate that most of the existing conveyance facilities have adequate capacity to move water through the system under the future scenarios. Some minor facility upgrades might be required as part of pond enlargements under a given pond scenario, such as piping for draining the pond. Increasing the capacity of the pipeline from Meadow Lane Pond to Delta Pond could allow reduced discharge from Meadow Lane Pond.

Additional Simulation Results: Graphs showing total system storage volume and total discharge for the following pond and demand scenarios are included in Attachment 2 of this TM.

� Pond Scenario 2, Demand Scenario 2, all five years � Pond Scenario 6, Demand Scenario 2, all five years � Pond Scenario 11, Demand Scenario 4, all five years

Also included in Attachment 2 are plots showing demand reductions for pond scenario 6, demand scenario 2, and for all five years.

ReferencesCH2M HILL. 2006. Laguna Agricultural Demands – Tier 1 and 2 Demand Levels. November 10.

Piazza, Randy. 2006. Personal communication regarding storage pond operating parameters. October 10.

Attachment 1 Summary Table of Results

TABLE 1-1Summary Table of ResultsIncremental Recycled Water Program – Water Reuse System Storage Model

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2 2 Driest 661 55 3 36 356 0 51 0 4,000 1,000 1,833 114 683 574 86 1,515 716 460 792 2 Dry 1,820 0 0 0 0 0 0 0 4,000 1,000 1,833 114 592 148 127 1,155 1,820 0 02 2 Median 2,586 74 1 0 130 0 2 0 4,000 1,000 1,721 104 675 462 87 1,538 2,660 100 1022 2 Wet 3,101 720 0 0 0 0 0 0 4,000 1,000 1,819 112 656 138 255 1,278 3,820 0 02 2 Wettest 3,849 851 4 0 400 50 4 1 4,000 1,000 1,634 97 700 625 69 1,557 4,700 400 1215 2 Driest 304 0 0 0 0 0 0 0 4,000 1,000 1,833 114 700 875 163 1,852 304 0 4165 2 Dry 1,827 0 0 0 0 0 0 0 4,000 1,000 1,833 114 592 148 109 1,153 1,827 0 05 2 Median 2,444 91 0 0 0 0 0 0 4,000 1,000 1,721 104 681 543 119 1,590 2,535 0 1545 2 Wet 3,081 784 0 0 0 0 0 0 4,000 1,000 1,819 112 649 138 218 1,257 3,865 0 05 2 Wettest 3,425 871 0 0 0 0 0 0 4,000 1,000 1,634 97 700 642 465 1,878 4,296 0 4426 2 Driest 304 0 0 0 0 0 0 0 4,000 1,000 1,833 114 700 875 179 1,852 304 0 4166 2 Dry 1,818 0 0 0 0 0 0 0 4,000 1,000 1,833 114 593 148 128 1,156 1,818 0 06 2 Median 2,445 88 0 0 0 0 0 0 4,000 1,000 1,721 104 676 543 132 1,587 2,533 0 1516 2 Wet 3,080 766 0 0 0 0 0 0 4,000 1,000 1,819 112 649 138 237 1,260 3,845 0 06 2 Wettest 3,424 848 0 0 0 0 0 0 4,000 1,000 1,634 97 700 642 478 1,876 4,272 0 440


RDD/070370001 (NLH2187.xls)


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RDD/070370001 (NLH2187.xls)


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2 4 Driest 247 0 0 0 0 0 0 0 4,000 1,200 1,833 114 1,453 148 10 1,229 247 0 02 4 Dry 1,132 0 0 0 0 0 0 0 3,952 1,180 1,820 113 1,283 143 10 1,228 1,132 0 02 4 Median 1,634 53 0 0 49 0 1 0 4,000 1,200 1,721 104 1,901 82 10 1,430 1,687 0 02 4 Wet 2,583 412 0 0 0 0 0 0 3,964 1,188 1,816 112 1,609 138 -2 1,331 2,995 0 02 4 Wettest 3,054 357 1 0 100 0 1 0 4,000 1,200 1,634 97 2,207 341 -22 1,572 3,411 100 1365 4 Driest 244 0 0 0 0 0 0 0 4,000 1,200 1,833 114 1,442 148 8 1,224 244 0 05 4 Dry 1,140 0 0 0 0 0 0 0 3,949 1,181 1,821 113 1,267 143 9 1,227 1,140 0 05 4 Median 1,593 48 0 0 0 0 0 0 4,000 1,200 1,721 104 1,842 188 8 1,464 1,641 0 285 4 Wet 2,559 465 0 0 0 0 0 0 3,960 1,188 1,816 112 1,591 138 -4 1,331 3,023 0 05 4 Wettest 2,932 405 0 0 0 0 0 0 4,000 1,200 1,634 97 2,263 373 -23 1,644 3,336 0 2086 4 Driest 243 0 0 0 0 0 0 0 4,000 1,200 1,833 114 1,457 148 10 1,229 243 0 06 4 Dry 1,130 0 0 0 0 0 0 0 3,951 1,181 1,820 113 1,284 143 10 1,228 1,130 0 06 4 Median 1,582 50 0 0 0 0 0 0 4,000 1,200 1,721 104 1,962 82 10 1,466 1,632 0 306 4 Wet 2,551 454 0 0 0 0 0 0 3,957 1,188 1,816 112 1,609 138 -2 1,332 3,006 0 06 4 Wettest 2,932 392 0 0 0 0 0 0 4,000 1,200 1,634 97 2,264 373 -22 1,639 3,324 0 203

10 4 Driest 245 0 0 0 0 0 0 0 4,000 1,200 1,833 114 1,441 148 8 1,224 245 0 010 4 Dry 1,141 0 0 0 0 0 0 0 3,948 1,181 1,821 113 1,266 143 9 1,227 1,141 0 010 4 Median 1,594 50 0 0 0 0 0 0 4,000 1,200 1,721 104 1,944 82 8 1,466 1,644 0 3010 4 Wet 2,567 457 0 0 0 0 0 0 3,958 1,188 1,816 112 1,591 138 -4 1,331 3,024 0 010 4 Wettest 2,937 397 0 0 0 0 0 0 4,000 1,200 1,634 97 2,265 373 -23 1,645 3,334 0 20911 4 Driest 244 0 0 0 0 0 0 0 4,000 1,200 1,833 114 1,456 148 10 1,229 244 0 011 4 Dry 1,131 0 0 0 0 0 0 0 3,951 1,181 1,820 113 1,283 143 10 1,228 1,131 0 011 4 Median 1,582 47 0 0 0 0 0 0 4,000 1,200 1,721 104 1,963 82 10 1,466 1,630 0 3011 4 Wet 2,553 449 0 0 0 0 0 0 3,958 1,188 1,816 112 1,610 138 -2 1,331 3,003 0 011 4 Wettest 2,922 384 0 0 0 0 0 0 4,000 1,200 1,634 97 2,275 379 -22 1,644 3,307 0 20812 4 Driest 245 0 0 0 0 0 0 0 4,000 1,200 1,833 114 1,456 148 10 1,229 245 0 012 4 Dry 1,132 0 0 0 0 0 0 0 3,952 1,180 1,820 113 1,283 143 10 1,228 1,132 0 012 4 Median 1,592 51 0 0 0 0 0 0 4,000 1,200 1,721 104 1,950 82 10 1,464 1,643 0 2812 4 Wet 2,565 446 0 0 0 0 0 0 3,955 1,187 1,815 112 1,604 138 -2 1,332 3,011 0 012 4 Wettest 2,959 382 0 0 0 0 0 0 4,000 1,200 1,634 97 2,246 373 -22 1,635 3,341 0 199

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6 5 Driest 303 0 0 0 0 0 0 0 4,400 1,000 1,833 455 0 875 139 1,991 303 0 5556 5 Dry 1,579 0 0 0 0 0 0 0 4,400 1,000 1,833 455 0 148 218 1,425 1,579 0 06 5 Median 2,359 168 0 0 0 0 0 0 4,400 1,000 1,721 416 0 82 559 1,734 2,527 0 2986 5 Wet 3,053 835 0 0 0 0 0 0 4,342 981 1,788 441 0 105 259 1,461 3,888 0 256 5 Wettest 3,416 825 0 0 0 0 0 0 4,400 1,000 1,634 389 0 642 526 2,086 4,240 0 650

10 5 Driest 328 0 0 0 25 0 25 0 4,400 1,000 1,833 455 0 839 134 1,966 328 0 53010 5 Dry 1,589 0 0 0 0 0 0 0 4,400 1,000 1,833 455 0 148 198 1,421 1,589 0 010 5 Median 2,373 149 0 0 0 0 0 0 4,400 1,000 1,721 416 0 82 556 1,747 2,522 0 31110 5 Wet 3,025 866 0 0 0 0 0 0 4,354 981 1,788 442 0 110 243 1,460 3,891 0 2410 5 Wettest 3,388 883 0 0 0 0 0 0 4,400 1,000 1,634 389 0 642 511 2,086 4,271 0 650

RDD/070370001 (NLH2187.xls)

Attachment 2 Volume and Discharge Plots

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