El Margarita Development Analysis

Transcription

1 303 Second Street, Suite 300 South San Francisco, California FAX: El Margarita Development Analysis 28 January 2015 Prepared for City of Yuba City 1201 Civic Center Boulevard Yuba City, CA K/J Project No *00

2 Table of Contents List of Tables... ii List of Figures... iii Section 1: Introduction... 1 Section 2: Evaluation Criteria Pipeline Criteria Booster Pumping Criteria Storage Criteria Fire Flow Criteria Peaking Factors... 3 Section 3: Model Update Pipeline Network Updates Demand Updates... 4 Section 4: System Demands Current Demand Estimate El Margarita Demand Estimate... 6 Section 5: System Analysis Storage Analysis Pumping Analysis Pipeline Analysis Conclusion List of Tables 2-1 Storage Evaluation Criteria 2-2 Firm Pumping Capacity 2-3 Fire Flow Demands 4-1 Fire Flow Demands 4-2 Land Use Demand Factors 4-3 Non-Residential Demands 4-4 Anticipated Demands 5-1 Existing Storage Facilities ii El Margarita Development Analysis, Yuba City Water System

3 Table of Contents (cont'd) 5-2 Storage Requirements 5-3 Existing Firm Booster Pumping Capacity List of Figures 4-1 Service Water from Yuba City Water Treatment Plant El Margarita Development Analysis, Yuba City Water System iii

4

5 Section 1: Introduction The development of the El Margarita area of the City of Yuba City (City) has been planned. The plan includes residential, commercial and other land uses, which will all contribute to the demands on the City s potable water system. This report analyzes the effects of the El Margarita development on the water system. The City of Yuba City last completed a Water Master Plan in 2004, and subsequently completed an update to the Water Master Plan in Portions of the areas described as Regions 2, 3 and 5 in the 2004 Water Master Plan (WMP) have now been fully integrated into the City s water distribution system, which has added to the overall demand that the City s water treatment plant and distribution system must supply. The hydraulic model of the distribution system was originally developed during the 1997 WMP project, updated during the 2004 WMP and the 2006 WMP Update projects, and was later updated by City staff to include some of the piping in Regions 2 and 3. Piping for Region 5 was already included in the model. The model is now in a hydraulic modeling software package called WaterCAD. In general, the City has large undeveloped areas on the west side of the City s boundary/service area where future development is expected to occur. One such development that is progressing is the El Margarita area. This area is bordered on the east by Harding Road and the south by Franklin Road. The western border is approximately halfway between George Washington Boulevard and Township Road. The western part of its northern border is along State Highway 20 between Western Parkway and Royo Ranchero. The eastern part of its northern border extends west from approximately the intersection of Redhaven Avenue and Carson Drive, ending approximately at Industrial Drive. Portions of the El Margarita area have already been developed. The area as a whole is expected to contain a variety of land uses that include: 1) Business, Technology & Light Industrial 2) Low Density Residential 3) Manufacturing, Processing & Warehousing 4) Medium/High Density Residential 5) Medium/Low Density Residential 6) Neighborhood Commercial 7) Parks, Recreation & Open Space 8) Public & Semi-Public 9) Regional Commercial This report analyzes the expected increase in demands from the El Margarita development and the effect of these demands on the potable water distribution system to determine if any improvement projects are triggered by this development. El Margarita Development Analysis, Yuba City Water System Page 1

6 Section 2: Evaluation Criteria The system evaluation criteria that were used to evaluate the effect of the planned El Margarita development area on the Yuba City water system were taken from the 2004 Water Master Plan Update and the 2006 Update to Water Demand and Infrastructure System Evaluation. The effect of the increased demands from the development of the El Margarita area will be determined by using these criteria to evaluate system performance. 2.1 Pipeline Criteria The criteria used to evaluate the operation of the distribution pipeline network are contained in Table 2-1 below. Table 2-1 Storage Evaluation Criteria System Criteria Maximum Day and Peak Hour Maximum Velocity Allowable Velocities Fire Flow Maximum Velocity Normal Operation Maximum Pressure Normal Operation Minimum Pressure Allowable Pressures Peak Hour Minimum Pressure Fire Flow Minimum Pressure (at all nodes) 7 fps 10 fps 60 psi 40 psi 30 psi 20 psi 2.2 Booster Pumping Criteria There are no storage facilities that supply the Yuba City distribution system via gravity. Therefore the pumping facilities must supply the demands in the system. The pumping facilities are considered to be adequately sized if the firm pumping capacity is equal to or larger than the peak hour demands on the system. For Yuba City, the firm pumping capacity is defined as the combined capacity of the pumping system with the largest single pump out of service. The largest pump is the 7.4 mgd pump located at the treatment plant. Table 2-2 below contains the firm pumping capacity of Yuba City s distribution system, as indicated in the 2004 Water Master Plan. Table 2-2 Firm Pumping Capacity Firm Pumping Capacity Location (MGD) Water Treatment Plant (Existing HLPS) 30 Booster Pumps at Sam Brannon Tank Site 1.3 Booster Pumps at Rowe Avenue Tank Site 1.3 Booster Pumps at Burns Tank Site 3.3 Booster Pumps at Harter Tank Site 10.8 Total 46.7 Page 2 El Margarita Development Analysis, Yuba City Water System

7 2.3 Storage Criteria The criteria used to evaluate the storage in the Yuba City system in the prior Water Master Plan updates, includes an operational storage of 25% of maximum day demands and emergency storage of 75% of average day demands. Fire flow storage requirements depend on the flow rate and length of time for different fire flow requirements. The largest fire flow storage value is 1,200,000 gallons, as calculated from a fire flow demand of 5,000 gallons per minute and a duration of four hours. 2.4 Fire Flow Criteria The minimum fire flow requirements for different land use categories are included in Table 2-3. The system must be capable of supplying these fire flow demands for a duration of four hours. Table 2-3 Fire Flow Demands Land Use Category Residential Low Density Residential Medium Density Commercial Industrial Schools, Hospitals, Civic Fire Flow Demand 2,000 gpm 3,000 gpm 5,000 gpm 5,000 gpm 4,000 gpm 2.5 Peaking Factors Peaking factors will be used to increase the average day demands to allow the evaluation of the system with the criteria listed in the sections above. According to the 2006 Water Master Plan Update, the maximum day demands are 2.0 times the average day demands. The peak hour demands are 3.5 times the average day demands. These same peaking factors were used in this analysis to calculate the maximum day and peak hour demands. El Margarita Development Analysis, Yuba City Water System Page 3

8 Section 3: Model Update The hydraulic model of the potable water distribution system was most recently updated by City staff to include some of the piping in Regions 2 and 3, which is part of the area known as Hillcrest. These areas have been converted from using groundwater to being supplied by the Yuba City distribution system, and are now included in the model. Since the last update to the model, additional pipelines have been constructed, and a new tank and pumping facility has been constructed. These changes to the system had to be incorporated into the hydraulic model before it could be used to perform an accurate evaluation of the distribution system. 3.1 Pipeline Network Updates Yuba City maintains a GIS database that includes almost all of the existing pipeline network. Recent pipeline construction projects have been incorporated into the GIS database with the exception of the Prop 84 Water Line Extension Project. Pipeline alignments from GIS were added to the model where updates were necessary. As-built drawings for the Prop 84 project were also used to update the model. Connectivity was updated for particular intersections to improve the accuracy of the model. The Sanborn tank and pumping facility were also incorporated into the model. 3.2 Demand Updates The demands have increased over the last few years, and are likely significantly different than the last time they were updated in The Hillcrest area of the model did not show any demands allocated to the model junctions in this area, indicating that a complete update to the demands was required to produce an accurate spatial distribution of the demands in the system. To accomplish this, water billing account data was spatially allocated through the geocoding process. Water billing data from 2012, 2013 and 2014 was used for approximately 21,000 accounts. Through the geocoding process, each billing record is geographically located in GIS using the address in the billing record. The end product of this process is a GIS shape file containing the billing records represented as a point, which can then be imported into WaterCAD. To allocate the water demands in the hydraulic model, demand nodes were selected that include all model nodes except those connected to water storage facilities, pumping facilities or large transmission pipelines. After the selection of demand nodes, each of the point demands corresponding to billing records is allocated to the nearest demand node in the model using the Load Builder routine. Page 4 El Margarita Development Analysis, Yuba City Water System

9 Section 4: System Demands The demands in the hydraulic model were updated to represent current demands on the system. Demands for the El Margarita development were also estimated to allow analysis of the effects of these demands on the water system. 4.1 Current Demand Estimate Information on the total demands in the system was received from Yuba City. This information included what is referred to as Service Water, which is the amount of water that is produced at the water treatment plant and pumped into the distribution system. During low demand periods of the day, portions of this water are diverted into storage facilities. During higher demand periods of the day, water from these storage facilities is pumped into the system to supplement what is being pumped into the system from the water treatment plant. The demands in the system could be estimated by adjusting the service water by the change in the amount of water stored in the storage facilities. However, because the City does not measure the rate of water that is entering at all of the storage facilities, it is not possible to accurately estimate the change in storage each day. Therefore, it was assumed that the change in storage would not greatly affect the total system demands if a long enough period of service water data was analyzed. In Figure 4-1, the service water rates from 1 December 2013 through 30 November 2014 are graphed. Figure 4-1 Service Water from Yuba City Water Treatment Plant El Margarita Development Analysis, Yuba City Water System Page 5

10 The average demands calculated from the service water data are million gallons per day (mgd), or 9,293 gallons per minute (gpm). The average demands from the three years of geocoded billing data were 9,995 gpm. Because the billing data was higher, it was used to represent average day demands in the model without further adjustment. Therefore, the total average day demands used in the model are 9,995 gpm, or 14.4 mgd. To represent maximum day and peak hour demands in the model, peaking factors from the 2006 WMP update were used. A peaking factor of 2.0 was used to scale the average day demands up to maximum day demands. A peaking factor of 3.5 was used to scale the average day demands up to peak hour demands. The total demands used for each scenario in the model are summarized in Table 4-1 below. Table 4-1 Fire Flow Demands Scenario Total Demands (gpm) Total Demands (mgd) Average Day 9, Maximum Day 19, Peak Hour 34, El Margarita Demand Estimate To estimate the demands within the El Margarita development, information on the expected land uses was analyzed, along with the billing data for existing demands within Yuba City. The existing billing data for particular non-residential land uses was analyzed to calculate demand factors in terms of gallons per day per acre (gpd/ac). These are summarized in Table 4-2 below. Table 4-2 Land Use Demand Factors Land Use gpd/ac Business, Technology & Light Industry 294 Community Commercial 1555 Manufacturing, Processing & Warehousing 4995 Neighborhood Commercial 1549 Office & Office Park 1121 Public & Semi Public 191 Regional Commercial 570 Information from the Draft Transportation Impact Study for the El Margarita Master Plan and the City s General Plan data was used to estimate the expected areas of new development for each land use for non-residential areas. These are areas within the El Margarita area that are not currently developed, and are referred to as Growth Areas. The General Plan land use designations for these areas, along with the demand factors in Table 4-2, were used to calculate demands for the non-residential areas within the El Margarita area in Table 4-3 below. Page 6 El Margarita Development Analysis, Yuba City Water System

11 Table 4-3 Non-Residential Demands Growth Demand Factor Demand Land Use Area (Acre) (gpd/acre) (gpm) Business, Technology & Light Industrial Community Commercial Manufacturing, Processing & Warehousing Neighborhood Commercial Office & Office Park Public/Quasi Public Regional Commercial For residential areas, water meter billing data was available for the existing residential development within the El Margarita area along Lynwood Drive and Hillview Drive. Using the area of these parcels and the average water usage from the billing data, a demand factor of 2,131 gallons per day per acre was calculated. This was used to calculate a total average day demand of 655 gpm for the acres for which demands are not currently available, or that are not yet developed. Most of the acres is undeveloped, but has been assigned a residential land use. However, there are housing areas in the El Margarita area that have recently been connected to the City distribution system by the pipelines that were constructed in the Prop 85 project. These housing areas do not have any billing information because they were supplied by private wells previously, and were therefore, included in the acres in order to be included in the overall demand estimate. The total average day demand calculated for the residential areas of the El Margarita area is 655 gpm. The residential and non-residential demand estimate calculations produced a total average day demand of 739 gpm, or 1.1 mgd. These were added to the existing demand scenarios in Table 4-4 below. This total average day demand of 739 gpm was added to the model at the intersection of George Washington Boulevard and Hillview Drive, which is in the center of the El Margarita area. Table 4-4 Anticipated Demands Scenario Existing Demands (mgd) El Margarita Demands (mgd) Anticipated Demands (gpm) Average Day Maximum Day Peak Hour El Margarita Development Analysis, Yuba City Water System Page 7

12 Section 5: System Analysis The City s distribution system was analyzed with the estimated demands for the El Margarita area to determine the effect that these demands will have on system operation, and to determine if any improvement projects are required for the system to supply these demands. 5.1 Storage Analysis The City s existing storage facilities are summarized in Table 5-1 below. As indicated in Section 2.3, the required storage is the sum of the operational, emergency and fire flow storage. The operational storage requirement is 25 percent of the maximum day demand. The emergency storage requirement is 75 percent of the average day demand. The fire flow storage is the largest fire flow storage value, which for Yuba City is 1.2 million gallons (MG). Table 5-1 Existing Storage Facilities Tank Site Total Storage Capacity (MG) Water Treatment Plant 8 Harter Tanks 4 Sam Brannon Tank 1 Rowe Avenue Tank 1 Burns Tank 3 Sanborn Tank 3.2 Total 20.2 The storage requirements, based on the average and maximum day demands, and the fire flow demands, are summarized in Table 5-2 below. The results show that the City will have a small storage deficiency in storage capacity in the distribution system when the anticipated increased demands from the El Margarita development are added to the system, as the storage requirement of 20.5 MG is higher than the existing storage of 20.2 MG. When the storage deficit is converted into acreage of residential areas, using the peaking factor of 2.0 and the landuse factor of 2,131 gpd/ac, the result is an equivalent residential development of 70 acres. One way to look at this is to assume that of the acres of residential areas within the El Margarita area, the current storage facilities can support the development of approximately of those acres, assuming that all non-residential areas are developed. Table 5-2 Storage Requirements Scenario Anticipated Demands (mgd) Requirement Storage Requirement (MG) Average Day 15.5 Emergency is 75% 11.6 Maximum Day 30.9 Operational is 25% 7.7 Fire Flow 1.2 Total 20.5 Page 8 El Margarita Development Analysis, Yuba City Water System

13 5.2 Pumping Analysis The City s existing firm booster pumping capacity is summarized in Table 5-3 below. The firm booster pumping capacity is defined as the combined capacity of all booster pumping facilities with the largest unit out of service. As the City s system is served exclusively by pumping facilities, the firm capacity should be equal to or greater than peak hour demand. Table 5-3 Existing Firm Booster Pumping Capacity Firm Pumping Capacity Location (MGD) Water Treatment Plant (Existing HLPS) 30 Booster Pumps at Sam Brannon Tank Site 1.3 Booster Pumps at Rowe Avenue Tank Site 1.3 Booster Pumps at Burns Tank Site 3.3 Booster Pumps at Harter Tank Site 10.8 Booster Pumps at Sanborn Tank Site 8.5 Total 55.2 As presented in Table 4-4, the anticipated peak hour demands after the El Margarita area is fully developed are expected to be 54.1 mgd. This is lower than the firm pumping capacity of 55.2 mgd, as presented in Table 5-3 above. Therefore, the existing pumping capacity is large enough to support the increase in demands from the development of the El Margarita area. 5.3 Pipeline Analysis The anticipated demands for the El Margarita area were added to the model to determine if the distribution system has sufficient capacity to support these demands. The updated model was run initially with only the pumps at the water treatment facility supplying the system. For each scenario, if the pumps at the water treatment facility were not sufficient, as indicated by pressures in the system that did not meet the pressure criteria, then additional pumps in the vicinity of the deficiency area were turned on to boost pressure. As indicated in Section 2.1, the normal operation minimum pressure is 40 psi and the peak hour minimum pressure is 30 psi. The minimum pressure under fire flow conditions is 20 psi. The model was run under each scenario and no pipeline capacity deficiencies were identified. For some scenarios, such as the peak hour with the El Margarita demands, and the fire flow with maximum day and fire flow demands, additional pump capacity was required to maintain the minimum pressures in the system. However, when sufficient pumping capacity was applied to the system, the model showed that the criteria could be met with the existing pipeline network. El Margarita Development Analysis, Yuba City Water System Page 9

14 5.4 Conclusion Given that the analysis showed that the existing pumping and pipeline facilities are adequate to support the additional demands for the El Margarita development, no additional pumping or pipeline facilities are anticipated to be needed to support complete development of the El Margarita area. The analysis showed that the City s current storage facilities are not sufficient to support the complete development of the El Margarita area. The storage deficit is calculated to be approximately 0.3 MG. Converting this to an equivalent area of residential development results in an area of approximately 70 acres. One way to interpret this is that the existing storage facilities can support the development of of the acres of residential area within the El Margarita area, assuming all of the non-residential areas are fully developed. Given that the City s distribution system is run with one single pressure zone, all of the storage facilities are assumed to support demands throughout the system. The effect of this is that increases in demands anywhere in the system will affect the need for storage. Therefore, as the El Margarita area is developed over time, development in other parts of the system would also affect the required storage capacity in the system. As the El Margarita area develops, specific parcel-level developments should be tracked to determine the expected level of demands. Commercial and industrial land uses can support a wide variety of demands. If particular developments are expected to be high water users, special accommodations may be needed. Likewise, if particular developments are low water users, or if special conservation measures or low-water-use development approaches are employed, demand projections for this area could be adjusted to reflect this. As much of the El Margarita area is undeveloped, it is anticipated that the pipeline network will be expanded as large parcels are subdivided. The pipelines needed to expand the pipeline network will need to be appropriately sized to support the required demands and fire flows for each area. Page 10 El Margarita Development Analysis, Yuba City Water System