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7041 Koll Center Parkway, Suite 110 Pleasanton, CA Phone [PHONE REDACTED] Fax [PHONE REDACTED] e-mail: [EMAIL REDACTED] TECHNICAL MEMORANDUM DATE: March 30, 2010 Project No.: 418-02-07-22 TO: Jack Bond, City of Modesto, Project Manager FROM: Charles Duncan, Project Manager SUBJECT: City of Modesto’s 2010 Water System Engineer’s Report Evaluation of the Existing and Buildout Water System for the Turlock Water Outlying Service Area (Turlock TM) In the mid 1990’s the City of Modesto (City) acquired the former Del Este Water System, which included the communities of Grayson, City of Waterford, Hickman, Del Rio, and a portion of the City of Turlock. The City now manages, operates and maintains these five outlying water service areas. As a component of the City's Engineering’s Report Project, the City has requested West Yost Associates (WYA) to provide an individual hydraulic assessment of each of these systems. The hydraulic evaluation of the City’s portion of the City of Turlock (Turlock) water system service area is addressed in this technical memorandum (TM). 1.0 SUMMARY The hydraulic assessment included three system components and the ability to serve current and buildout demands: groundwater pumping capacity; storage capacity; and distribution system needs. In addition, water supply requirements at buildout were evaluated; additional demands at buildout are minimal and do not require a change in the proposed facility plan. 1.1 Groundwater Pumping Capacity The system assessment evaluated the adequacy of existing production wells to meet current water demands for two conditions: peak hour and maximum day plus fire flow conditions. Peak hour and maximum day demand were calculated as 755 gallons per minute (gpm) and 583 gpm, respectively. The system was reviewed with all wells producing, and with the largest well out of service reliable pumping capacity). The reliable pumping capacity was sufficient to meet maximum day and peak hour demand conditions; however it was not sufficient to meet maximum day plus fire flow conditions. Recommendations to provide the supply include constructing additional storage and rehabilitating or replacing a well. The recommendations also apply to storage issues and are discussed further in the following section. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 2 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI 1.2 Storage Capacity The storage capacity assessment evaluated total storage and peaking capacity requirements based on three criteria: operational storage; fire storage; and emergency storage. Operational storage was established as 25 percent (25%) of a maximum day demand. Fire flow demand was established as 1,500 gpm for a 2-hour duration. Emergency storage was established as one day’s worth of average day demand. The Northern and Central areas have a total storage deficiency of 0.58 MG. It is recommended that the City construct a storage tank and associated 1.74 mgd pump station with backup power to provided needed storage for these combined areas. The Southern service area has a storage deficiency of 0.60 MG. Rehabilitating (or replacing) Well 255 to provide a pumping capacity of 700 gpm will address this issue without the need for additional storage facilities. 1.3 Existing Distribution System The City has established a minimum requirement of 40 pounds per square inch (psi) of system pressure to meet peak hour demand, and 20 psi of residual pressure, measured at the flowing hydrant, to meet maximum day demand plus fire flows. Also, head loss should remain below 7 feet per 1,000 feet (ft/kft) of distribution piping, and velocity should be not greater than 7 feet per second (fps). WYA developed the system hydraulic model using MWH Soft’s H2ONET software. Model inputs included pipe, junctions, wells, tanks, and pumps. Additional information about the hydraulic model is provided in Attachment A. WYA’s hydraulic modeling of the City’s portion of the Turlock water service area indicates that the existing supply system of four operational wells can maintain a minimum system pressure of 40 pounds per square inch (psi) during a simulated peak hour demand condition, however it cannot maintain the 20 psi residual system pressures during a simulated maximum day plus fire flow demand condition. Due to the existing system configurations of each of the service areas, the ability to build in independent (without City of Turlock assistance) system redundancy and reliability is very limited. Two capital improvement alternatives are proposed to correct these existing system deficiencies. Alternative A is anticipated to cost approximately $3.5M, and Alternative B is anticipated to cost approximately $6.6M, as detailed in Tables 7A and 7B, respectively, located at the end of this TM. The difference between Alternative A and Alternative B is the level of inter-agency cooperation provided by the City of Turlock. Alternative A assumes that the City of Turlock will provide a total of three full sized (8-inch diameter) emergency interties, one in each of the City’s water service areas. The possible upgrade of two existing emergency connection points, and the installation of a new emergency connection eliminates the need for the City to construct above ground storage facilities (and associated pump stations), and/or new groundwater wells. Alternative B assumes that the City of Turlock will provide the City with one additional emergency intertie connection point, located in the City’s Southern service area. New storage facilities are also required for Alternative B. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 3 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Alternative A Rehabilitate or replace Well 255. Install backup generators at all four existing well sites. Upsize 10,400 linear feet of existing pipeline. Explore institutional arrangements with the City of Turlock to upsize two existing system emergency interconnections, and install a new emergency intertie into the three City water service areas. OR Alternative B Rehabilitate or replace Well 255. Install backup generators at all four existing well sites. New storage tank, with 0.58 MG of useable storage, and associated 1.74 mgd pump station with standby power for the northern and central service area islands. 6,500 linear feet of new pipeline and 10,400 linear feet of upsized pipeline. Enter into discussion within the City of Turlock, and if an agreement is reached, install an emergency intertie with the City of Turlock system in the City’s Southern water service area. 1.4 Buildout Distribution System The existing Turlock water service area is assumed to be at full buildout. Therefore, additional improvements to the recommended existing capital improvements presented above for future growth demand is assumed not necessary. 2.0 INTRODUCTION In 2002, the City requested WYA to provide engineering services to assist in the development and calibration of a water system hydraulic model for the City’s portion of the Turlock water service area. Using the methodology described in this TM, WYA developed a hydraulic network analysis model of the Turlock water distribution system to allow computer simulations of various current demands and flow conditions. The developed hydraulic model was used to evaluate the following demand conditions: Maximum day, Peak hour, and Maximum day plus fire flow. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 4 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI In order to create a hydraulic network analysis model representative of the Turlock water system, WYA completed the steps listed below: Used shapefiles exported from the City’s Geographical Information System (GIS) and existing hard copy maps to develop the hydraulic model. Verified with City Operations staff that the converted hydraulic model system configuration (pipeline sizes, alignments, connections, and other facility sizes and locations) is representative of the current Turlock water system. Evaluated existing water demands to ensure proper distribution of demands in the hydraulic model. In accomplishing these tasks, WYA worked closely with City Engineering and Operations staff to obtain and review the following: as-built drawings and maps to confirm pipeline sizes, material, age, locations and alignments; and land use and available metered data. Based on this water system information, WYA developed a water distribution system hydraulic model of the Turlock water service area under 2002 conditions. Since the development and calibration of the hydraulic model in 2002, there have been few changes to the Turlock water system. No changes have been made to the existing system infrastructure. Demands have been updated based on an average of the 2001 through 2006 production data. As recommended by the City, an average value was used due to an incomplete data set between July 2003 and June 2005. The 2002 model has been updated to reflect the changes in the system demands. This TM presents the updates performed, model results, and recommended facility improvements. This memo is organized as follows: Service Area Existing Water System Turlock Hydraulic Model Existing Water Supply System Evaluation & Recommendations Buildout Water Supply System Evaluation & Recommendations 3.0 SERVICE AREA The Turlock water service area is made up of three small, separate, service area islands (“Northern”, “Central” and “Southern”) located within the Turlock water system. The City of Modesto’s Turlock water service area is an independent water system, with two existing emergency water supply connections to the Turlock water system in the Northern and Central service areas (owned and operated by the City of Modesto). The Turlock water service area is located approximately 14 miles south of the City (see Figure 1 inset). ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 5 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI The Northern service area is bounded by East Monte Vista Avenue to the north, James Lane to the east, Hedstrom Road to the south, and Geer Road to the west. The Central service area is bounded by Delbon Avenue to the north, Runyan Drive to the south, Colorado Avenue to the east and North Olive Avenue to the west. The Southern service area is essentially a two service block area, connected via a pipeline along Brier Road. The entire Turlock service area contains approximately 99 acres, primarily residential, and is considered fully developed. These service areas were originally provided with water service by the Del Este Water Company. In the mid 1990’s, the City acquired the Del Este Water System and began providing water service. 4.0 EXISTING WATER SYSTEM The Turlock water service area includes a total of four existing wells, no storage tanks, and approximately 23,000 linear feet of pipeline. Existing Turlock pipelines vary in size from 4-inches, up to 8-inches in diameter. There are currently hard valved, emergency interconnections between the Northern and Central service areas and the separate, existing Turlock water distribution system. The Southern service area currently has no emergency interconnections with the Turlock water system; however, such an interconnection may be required to meet the City’s fire flow requirements. 4.1 Sources of Supply Details and data on capacity and operations of Turlock’s four wells (Well 255, 256, 275, and 306) and condition of the distribution and transmission mains are incomplete; the most accurate data is currently available from the City. The evaluation completed by WYA of the Turlock water service area is based on this currently available information. 4.1.1 Wells The Turlock water system is solely supplied by groundwater. Of the four existing wells, three are currently operational. These wells discharge groundwater directly into the distribution system. Well 306, which serves the Central service area, has been offline since May of 2009 due to elevated nitrate levels. Demand for this area is currently being met by the City of Turlock. Chlorine is added at all wellheads to provide disinfection (see Figure 1 for well locations). Well characteristics are summarized in Table 1. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 6 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Table 1. Well Characteristics(a) History Pump Data Well Construction Details Well No. Address Year Drilled Rated Pump Capacity (at 60 psi), gpm(b) Rated Hp Standby Power Treatment System Casing Diameter (inches) Gravel Packed Depth of Annular Seal Casing Depth Perforated From/To Total Depth 255 902 S. Minaret 1950/89 600 40 No No 8 No 280 308 None 348 256 305 Hedstrom Rd 1967/73 250 20 No No 10 No 128 188 None [PHONE REDACTED] Brier Road 1973 515 40 No No 20/16/14 No 52 256 180-252 272 306 917 Carolyn Dr. NP(c) NP NP No No 8 No 50 320 200-210, 300-230 335 Based on information provided by the City. gpm = gallons per minute NP = Not Provided by City Wells 255, 256, 275, and 306 were tested for pump efficiency tests in 2007. Results of those tests are shown in Table 2. Table 2. Well Pump Tests Well No. Date Tested Motor HP Measured Flow, gpm Static Level, ft(a) Pumping Level, ft(a) Discharge Pressure, psi Water HP 255 09/24/07 40 240 NA NA 60 NA 256 09/24/07 20 250 79 83 55 13.26 275 09/25/07 40 450 80 88 60 25.75 306 10/04/07 20 210 NA NA 50 10.55 Static and Pumping Levels indicate depth to water measurements from reference point elevations. NA = Information not available ft = feet psi = pounds per square inch HP = horsepower Table 3 provides a summary of the total groundwater production of each individual well in 2008. Figure 2 provides a graphical summary of the 2008 data. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 7 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Table 3. Summary of Turlock Service Area Production in 2008(a) Well 255 Well 256 Well 275 Well 306 Month gallons MG Gallons MG Gallons MG Gallons MG January 3,606,964 3.61 455,414 0.46 9,273 0.01 148,024 0.15 February 3,011,798 3.01 422,946 0.42 610,516 0.61 3 0.00 March 3,658,085 3.66 714,088 0.71 2,513,537 2.51 94,880 0.09 April 7,388,374 7.39 1,077,420 1.08 1,479,024 1.48 297,369 0.30 May 8,763,834 8.76 1,458,961 1.46 2,833,805 2.83 16,979 0.02 June 8,492,049 8.49 1,550,367 1.55 4,038,910 4.04 27,722 0.03 July 8,457,200 8.46 1,775,752 1.78 4,680,548 4.68 24,173 0.02 August 8,548,583 8.55 1,584,090 1.58 3,922,549 3.92 2,131,519 2.13 September 8,290,513 8.29 1,287,138 1.29 1,972,298 1.97 1,675,809 1.68 October 5,185,084 5.19 983,347 0.98 2,635,648 2.64 513 0.00 November 1,615,371 1.62 550,729 0.55 4,222,226 4.22 0 0.00 December 4,108,920 4.11 296,641 0.30 246,566 0.25 4 0.00 Subtotal 71,126,774 71.13 12,156,892 12.16 29,164,899 29.16 4,416,994 4.42 Total Annual Supply 116.87 Data provided by the City of Modesto on September 4, 2009, from the file well flow totals 2002 to present.xls”. 4.1.2 Wellhead Treatment Chlorine is the only wellhead treatment provided, and it is provided at all of the well facilities in the Turlock service area. 4.1.3 Storage There are currently no storage facilities or pumping plants (other than the well pumps) in the Turlock service area. 4.1.4 Pipelines General knowledge of the Turlock service area pipeline main locations and material type was gained through discussion with the City’s Operations staff. Pipelines within the service area range from 4-inch to 8-inch diameter, and are mainly constructed of welded steel. Pipelines in the northern and central service areas are approximately 50 to 60-year old 4-inch diameter unlined steel pipelines. The southern service area has pipelines that range from 4-inches to 8-inches in diameter, and are mainly constructed of asbestos cement and unlined steel pipe. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 8 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI 5.0 DEVELOPMENT OF THE TURLOCK WATER SERVICE AREA HYDRAULIC MODEL WYA developed a hydraulic model of the Turlock water service area using the MWH Soft’s H2ONET hydraulic modeling software. A summary of the detailed development of this model is included in Attachment A of this TM. 6.0 EVALUATION OF EXISTING WATER SUPPLY SYSTEM 6.1 Overview This section presents the hydraulic evaluation of the Turlock water service areas existing water distribution system, and its ability to meet the City’s recommended water system operational criteria under existing demand conditions. The existing water distribution system was evaluated under the following demand scenarios: Maximum day demand, Peak hour demand, and Maximum day demand plus fire flow. 6.2 Potable Water Demands Average day potable water demands for the existing Turlock system were estimated and allocated based on the methodology described in Attachment A. The average day demand was calculated based on a 6-year average from 2001 through 2006, based on discussions with City staff.1 The average day demand from 2006 was not used because 2006 was not considered a typical year. Data was also incomplete from July 2003 through June 2005, therefore data from 2002 was substituted in order to calculate the average day demand. Based on production data provided by the City of Modesto from 2005 through 2007, Table 4 shows the peaking factors used to estimate maximum day and peak hour demands. The maximum day peaking factor was developed based on a 3-year average from 2005 through 2007. The peak hour peaking factor was developed based on a 2-year average from 2006 through 2007. The peaking factors were estimated and allocated based on the methodology described in Attachment A. 1 Discussions occurred during a conference call with City staff on January 24, 2008. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 9 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Table 4. Water Demand Peaking Factors Average 2001-2006 Demands Demand Condition Peaking Factor(a) mgd gpm Average Day 0.43 296 Maximum Day 1.97 x Average Day 0.84 583 Peak Hour 2.55 x Average Day 1.09 755 Based on available water production data from the City. 6.3 Pumping Capacity Evaluation The Turlock service areas are supplied exclusively by groundwater. At the time of this hydraulic analysis, there were four existing production wells that were all operational. The Northern area and Central area each have one well, and the Southern area has two wells. Well 306, which serves the Central service area, has been offline since May of 2009 due to elevated nitrate levels. Demand for this area is currently being met by the City of Turlock. Table 5 provides a summary of recent pump flow testing for each well, with the exception of Well 255 (flow for Well 255 was estimated based on rated pump capacity provided by the City). Since the Turlock service area consists of three isolated islands, each area’s pumping capacity was evaluated independently. Based on the information available, the Northern area has a total existing supply capacity of 250 gpm, Central area has 210 gpm, and Southern area has 690 gpm. However, for water supply planning purposes, this groundwater supply (groundwater pumping capacity) must be reduced to account for a well or wells that are out of service at any given time due to mechanical breakdowns, maintenance, or other operational issues. This reduced pumping capacity is defined as the Reliable Pumping Capacity. The City has defined the reliable groundwater supply as the system’s groundwater pumping capacity assuming the largest well is out of service. The potable water demands presented in Table 4 are based on average data that does not separate each individual service area. In order to complete the pumping capacity evaluation, data collected in 2006 was used to represent average day demands for each area. The peaking factors in Table 4 were then used to obtain maximum day and peak hour demands of 51 gpm and 66 gpm for the Northern Area; 26 gpm and 33 gpm for the Central Area; and 355 gpm and 459 gpm for the Southern Area. As shown on Table 5, the current reliable existing system pumping capacities at each of the service areas are not sufficient to meet maximum day, peak hour, or maximum day plus fire flow demand conditions. Since these areas are completely built out, there is no available space to install additional wells in each of these service areas. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 10 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI In the Northern and Central areas, this deficiency is due to the lack of backup power sources at the single wells. It is recommended that the City install backup generators at Wells 256 and 306 in order to remedy the reliable pumping capacity deficiency. In addition, WYA recommends creating a formal agreement with City of Turlock to ensure that water will be delivered to these areas in the event that the single supply well supplying this area is taken offline for anything other than a power outage. Another possible solution is to utilize the storage facilities discussed in the Storage Capacity Evaluation portion of this TM. In the Southern area, though there are two wells and one can be assumed to remain on in the event of an emergency, the total reliable pumping capacity of 240 gpm is not sufficient to meet the existing maximum day demand of 355 gpm. Similar to the Northern and Central areas, it is recommended that the City install backup generators at both Wells 255 and 275 to fix the reliable pumping capacity deficiency, and formalize an agreement with City of Turlock to ensure that water supply is still available to this area in the event of another emergency. Table 5. Summary of Existing System’s Pumping Supply Facilities Well Pump Name Efficiency, percent Standby Power Existing Capacity, gpm(a) Existing Maximum Day Demand(b), gpm Existing Peak Hour(b), gpm Existing Maximum Day plus Fire Flow, gpm 256 54 No 250 50 66 1,550 Total Reliable Capacity – Northern Area 0 Deficient Deficient Deficient 306(d) 35 No 210 26 33 1,526 Total Reliable Capacity – Central Area 0 Deficient Deficient Deficient 255 NA(c) No 240 275 58 No 450 Total Capacity – Southern Area 690 355 459 1,855 Total Reliable Capacity – Southern Area 240 Deficient Deficient Deficient Based on pump test flow from August through September 2007 conducted by City operations staff. Breakdown of demands based on Average Day demands calculated using 2006 system flows for each area. Maximum Day and Peak Hour demands based on Average Day demand multiplied by peaking factor identified in Table 4. NA = Information not available Well 306 has been offline since May 2009 due to high nitrates. The Central Area is currently being served directly from the City of Turlock. 6.4 Storage Capacity Evaluation Criteria have been defined for determining treated water storage and system peaking capacity needs to meet diurnal operational peaks, fire flows, and emergency conditions. Total storage and system peaking capacity requirements can be evaluated based on the following three components: ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 11 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Operational Storage: 25 percent of maximum day demand; Fire Storage: The required fire flow times the fire flow duration period, as required by the City’s Fire Marshall; and Emergency Storage: 1 times average day demand. As discussed previously, complete historical demand data for each region (Northern, Central, and Southern) between 2001 and 2006 was not available. The storage volumes in Table 6 were updated by scaling the 2002 demands in proportion to the ratio of the average of 2001 through 2006 total demands and the 2002 demands. The Turlock system currently does not have any tanks or storage reservoirs; therefore, all of its available storage capacity and ability to meet peak operational demands is based on groundwater basin storage and pumping capacity. The Turlock system is entirely dependent on the groundwater basin for storage. As shown on Table 6, the service area has storage deficiencies of 0.33 MG, 0.25 MG, and 0.38 MG in the Northern, Central, and Southern service areas, respectively. Since the Northern and Central islands only have single wells with no backup power, the reliable capacity at these two service areas is essentially 0 MG. The Southern island has two wells, and so the reliable capacity is equivalent to the pumping capacity with the largest well taken out of service, as indicated on Table 5. In order to remedy this storage deficiency, it is recommended that the City construct a storage tank for its Turlock water service area. If the three service areas were small and located relatively close to each other, it would be preferable to install a single reservoir capable of serving all three service areas. However, the Southern service area is more than two miles from the Northern and Central service areas. Therefore, a joint storage facility for all three service areas does not appear to be practical, and storage options for these two areas (Southern area and Northern/Central area) were considered separately. The Northern and Central areas have a total storage deficiency of 0.58 MG (0.33 + 0.25 MG); it is recommended that the City construct a 0.58 MG storage tank and associated 1.74 mgd pump station with backup power to provided needed storage for these combined areas. The storage tank should be located between the two service areas. The Southern service area has a storage deficiency of 0.38 MG; replacing Well 255 to provide a pumping capacity of 700 gpm will address this issue without the need for storage facilities. An alternate remedy is to construct a 0.6 MG storage tank and 1.8 mgd booster pump station. However, once cost benefits were weighed, the former recommendation is preferred. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 12 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Table 6. Summary of Required Above Ground Storage(a) Storage Component Component Detail North Area, MG Central Area, MG South Area w/o New Well, MG South Area w/ New Well, MG Operational 0.25 x maximum day demand 0.05 0.02 0.13 0.13 Fire 1500 gpm for 2 hours 0.18 0.18 0.18 0.18 Emergency 1.00 x average day demand 0.10 0.05 0.28 0.28 Subtotal 0.33 0.25 0.59 0.59 Groundwater Credit(b) 60% reliable production capacity (0.00)(c) (0.00)(c) (0.21)(d) (0.60) Total Storage Required 0.33 0.25 0.38 0.00 Storage demands for individual service areas are estimated based on historical data. Sixty percent of existing reliable groundwater pumping capacity (with largest well out of service). Northern and Central service areas only served by a single well with no backup power generator, so the reliable capacity is zero. Southern service area served by two wells, so reliable capacity is equivalent to the pumping capacity with the larger well out of service (Well 275). 6.5 Existing Distribution System Evaluation Hydraulic analyses were conducted to identify areas of the City's Turlock Water Service Area where minimum design pressures could not be maintained, or where velocities and/or head losses were found to exceed City design standards. Detailed discussion is provided in the following sections. 6.5.1 Peak Hour Demand Conditions The peak hour demands for the Turlock service area under existing conditions are approximately equal to 1.09 mgd ( 755 gpm). This peak hour demand condition was simulated in the model for each of the three individual service areas. The results indicated that the existing distribution system could adequately deliver these demands under the City’s minimum pressure criteria of 40 psi. The hydraulic analysis indicates that there will be adequate pressure available in all the service areas with all wells fully operational (see Figure 6.5.2Maximum Day Plus Fire Flow Demand Conditions Fire flows are to be met concurrently with a maximum day demand condition, while maintaining a minimum residual system pressure of 20 psi, as measured at the flowing hydrant. The fire flow demand for the Turlock water system is 1,500 gpm. Based on the analysis of the maximum day plus fire flow demand condition, Turlock’s existing water system cannot maintain a minimum residual system pressure of 20 psi in any of the three Turlock water service areas, even with all existing wells assumed to be operating (see Figure ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 13 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI The pressure deficiency in the Northern and Central service areas is caused by insufficient supply and undersized pipelines. The existing active wells are not capable of supplying the necessary 1,500 gpm fire flow in each service area; additional supply and pumping capacity are necessary to resolve this problem. As mentioned above, a storage tank with a useable capacity of 0.58 MG located between the Northern and Central service areas is recommended (see Figure 5) to provide additional capacity. With the addition of this new storage tank, associated 1.74 mgd booster pump station, and replacement of the existing 4-inch pipelines with 8-inch diameter pipelines, a 20 psi minimum residual system pressure during a maximum day plus concurrent fire flow conditions will be possible. The supply deficiency and corresponding inability to provide a minimum residual system pressure of 20 psi during a maximum day demand and concurrent fire flow in the southern service area can be rectified through the installation of an emergency intertie with the City of Turlock water system. In order to accommodate the increased supply, pipelines that are 4-inch diameter in the southern service area should be replaced with 8-inch diameter pipelines to ensure that head loss and velocity criteria are met. The construction of this new emergency system interconnection and upsizing existing 4-inch diameter pipelines would mitigate the system deficiencies previously identified in this southern service area. For the northern and central service areas, a potential alternative to the construction of the 0.58 MG storage tank is to increase the size of the existing emergency interconnections from 2-inch in the northern service area and 4-inch in the central service area to 8-inch diameter connections. Since the City of Turlock’s water distribution system surrounds the small, City-owned Turlock water service area, increasing the size of these emergency interconnections for the limited purpose of mutual aid could provide a more cost-efficient solution than constructing new, independent facilities. The City of Modesto should explore and discuss other alternatives of this nature with the City of Turlock to find the most cost effective and reliable solution. 7.0 RECOMMENDED WATER SYSTEM IMPROVEMENTS Based on the evaluation of the Turlock service area water system, there is a need for various water facility improvements throughout the service area. An overview of the recommended facilities is provided on Figure 5. A summary discussion of the prioritized recommended improvements is provided below. 7.1 Existing System Program Listed below are two recommended capital improvement alternatives which will mitigate the identified system pressure and supply deficiencies previously discussed in this technical memorandum: ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 14 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI Alternative A Rehabilitate or replace Well 255. Install backup generators at all four existing well sites. Construct 10,400 linear feet of upsized pipeline. Explore institutional arrangements with the City of Turlock to upsize two existing system emergency interconnections, and install a new emergency intertie into the three City water service areas. OR Alternative B Rehabilitate or replace Well 255. Install backup generators at all four existing well sites. Construct a new storage tank, with 0.58 MG of useable storage, and associated 1.74 mgd pump station with standby power for the northern and central service area islands. Install 6,500 linear feet of new pipeline and 10,400 linear feet of upsized pipeline. Enter into discussions with the City of Turlock, and if agreement is reached, install an emergency intertie with City of Turlock system in the southern water service area. Location of the recommended improvements are shown on Figure 5 and associated costs are detailed in Tables 7A and 7B. With the completion of either of these recommendations, the existing water service areas will be able to meet all City water system performance criteria. 7.2 Required On-going Rehabilitation Improvements In addition to the need to construct system improvements to meet current water system demands, the City should plan to repair/replace aging water system infrastructure. The decision to repair or replace existing facilities should be based primarily on facility condition. Corroding pipelines with reasonable structural integrity may often be repaired (instead of replaced), as it is more cost effective and less disruptive than replacement and usually provides a comparable useful life of the pipeline. Extremely deteriorated pipelines must be replaced, as these facilities cannot be repaired in a cost-effective manner. Capital Costs of Recommended Improvements The estimated probable capital costs for the recommended water system improvements to serve Turlock’s existing and buildout condition are presented in Tables 7A and 7B. The capital costs are presented in March 2010 dollars at an Engineering News Record (ENR) construction cost index (CCI) of 9728.17 consistent with San Francisco. The costs include an estimate of 50 percent on the estimated construction cost to account for administration, design, and engineering costs and other contingencies. The costs for the facilities do not include costs for annual operation and maintenance, or costs for acquisition of rights-of-way. ---PAGE BREAK--- CIP CIP Unit Cost Option A Cost ID Reason Item Unit Quantity Pipelines FF03 Fireflow Northern Service Island 4-inch Diameter Pipelines 8-inch lf 2,300 101 235,000 FF04 Fireflow Central Service Island 4-inch Diameter Pipelines 8-inch lf 2,400 101 245,000 FF05 Fireflow Southern Service Island 4-inch Diameter Pipelines 8-inch lf 5,700 101 578,000 Wells Supply Rehabilitate or Replace Well 255 ls 1 550,848 551,000 Well Backup Generators Supply Well 255 ls 1 133,000 133,000 Supply Well 256 ls 1 133,000 133,000 Supply Well 275 ls 1 133,000 133,000 Supply Well 306 ls 1 133,000 133,000 Interconnection Emergency Interconnection to City of Turlock Water System - Northern Service Island each 1 55,085 55,000 Emergency Interconnection to City of Turlock Water System - Central Service Island each 1 55,085 55,000 Emergency Interconnection to City of Turlock Water System - Southern Service Island each 1 55,085 55,000 Subtotal (Overall Program) 2,306,000 50% Contingency & Other Costs 1,153,000 Alternative A - Total Estimated CIP Construction Cost 3,459,000 Table 7A. Alternative A - Recommended CIP Program for Existing Turlock System Does not include site specific facilities. All unit prices presented in SF March 2010 dollars (ENR Construction Index = 9728.17). Unit prices based on combination of cost curves, construction cost guidelines and similar construction projects. Backup generator cost estimated at $200,000 per generator (including soft costs). Well 255 flow based on production information provided by City. Assumes cost to install 8-inch diameter PRV. Does not include costs to attending meetings with the City of Turlock to discuss, negotiate and obtain approval to install this emergency intertie. West Yost Associates o:\c\418\02-04-22\wp\er\20091031ceI3 T7A Last Revised: 09/11/08 City of Modesto Engineer's Report Appendix I Turlock TM ---PAGE BREAK--- CIP CIP Unit Cost Option B Cost ID Reason Item Unit Quantity Pipelines FF01 Fireflow Pipeline from Proposed Tank 1 to Northern Service Island 8-inch lf 2,600 101 263,000 FF02 Fireflow Pipeline from Proposed Tank 1 to Central Service Island 8-inch lf 3,900 101 393,000 FF03 Fireflow Northern Service Island 4-inch Diameter Pipelines 8-inch lf 2,300 101 235,000 FF04 Fireflow Central Service Island 4-inch Diameter Pipelines 8-inch lf 2,400 101 245,000 FF05 Fireflow Southern Service Island 4-inch Diameter Pipelines 8-inch lf 5,700 101 578,000 Storage Tank Supply 0.58 MG Storage Tank ls 0.58 799,000 799,000 Supply 1.74 MGD Pump Station with standby power hp 107 1,044,000 1,044,000 Wells Supply Rehabilitate or Replace Well 255 ls 1 550,848 551,000 Well Backup Generators Supply Well 255 ls 1 133,000 133,000 Supply Well 256 ls 1 133,000 133,000 Supply Well 275 ls 1 133,000 133,000 Supply Well 306 ls 1 133,000 133,000 Interconnection Emergency Interconnection to City of Turlock Water System - Southern Service Island each 1 55,085 55,000 Subtotal (Overall Program) 4,695,000 50% Contingency & Other Costs 2,347,500 Alternative B - Total Estimated CIP Construction Cost 7,042,500 Table 7B. Alternative B - Recommended CIP Program for Existing Turlock System Does not include site specific facilities. All unit prices presented in SF March 2010 dollars (ENR Construction Index = 9728.17). Unit prices based on combination of cost curves, construction cost guidelines and similar construction projects. Backup generator cost estimated at $200,000 per installation (including soft costs). Well 255 flow based on production information provided by City. Assumes cost to install 8-inch diameter PRV. Does not include costs to attending meetings with the City of Turlock to discuss, negotiate and obtain approval to install this emergency intertie. West Yost Associates o:\c\418\02-04-22\wp\er\20091031ce4 T7B Last Revised: 09/11/08 City of Modesto Engineer's Report Appendix I Turlock TM ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 17 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceI1AppI 8.0 EVALUATION OF BUILDOUT WATER SUPPLY SYSTEM Since the Turlock water service area is already fully built-out, no additional analysis or infrastructure recommendations are necessary for the buildout water supply system. However, to ensure adequate continued service for the Turlock service area customers, the City should develop and implement a rehabilitation and replacement program for the service area’s aging pipelines. ---PAGE BREAK--- ---PAGE BREAK--- West Yost Associates o:\c\418\02-04-22\wp\er\Fig_02 Last Revised: 11/05/09 City of Modesto Engineer's Report Appendix I Turlock TM Figure 2. City of Turlock (Modesto Portion) - Production by Well (2008) 0 2,000,000 4,000,000 6,000,000 8,000,000 10,000,000 12,000,000 14,000,000 16,000,000 18,000,000 January February March April May June July August September October November December Month Production (Gallons) Well 255 Well 256 Well 275 Well 306 Notes: - Data based on well production information in Table 3. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ATTACHMENT A Development of the Turlock Water Service Area Hydraulic Model ---PAGE BREAK--- West Yost Associates A-1 o:\c\418\02-07-22\wp\er\20091031ce2AttA ATTACHMENT A. DEVELOPMENT OF TURLOCK’S WATER SERVICE AREA HYDRAULIC MODEL West Yost Associates (WYA) developed a hydraulic model of the City of Modesto’s portion of the City of Turlock’s (Turlock) service area using MWH Soft’s H2ONET hydraulic modeling software. The distribution system depicted in the AutoCAD file provided by the City of Modesto (City) was replicated as pipe, junctions, wells, tanks, and pumps. In 2010, this model was converted to MWH Soft’s InfoWater v7.0. Modeling Assumptions and Criteria Establishing computer modeling assumptions and criteria was important for the development of the model, calibrating and running the model, and interpreting the results of the computer runs. The assumptions and criteria that were used to develop the Turlock service area water distribution system hydraulic model are described below: A minimum pipe size of 4 inches was modeled. Information on pipe length, diameter, material type and age was extracted from the City’s existing Geographical Information System (GIS) and hard copy maps. Pipe roughness coefficients (C-factors) were assigned based on age and pipe material. Pump station piping configurations, performance curves, and motor size information were acquired from site visits, “as-built” plans and interviews with City operational staff. Pipe length accuracy was assumed to be ±25 feet. Ground surface elevations were estimated using available digital topographic maps and surveyed benchmark elevations. Elevations were estimated to the nearest foot where spot elevations were not available. The water demands in the model were expressed in gallons per minute (gpm). Average Day Demand The average day demand was calculated based on a 6-year average from 2001 through 2006. Data for the Turlock system was incomplete from July 2003 through June 2005, therefore data from 2002 was substituted in order to have six consecutive years for calculating the average day demand, as shown in Table 1. This methodology was based on discussions with City staff on January 24, 2008. ---PAGE BREAK--- West Yost Associates A-2 o:\c\418\02-07-22\wp\er\20091031ce2AttA Table 1. Average Day Demand(a) Month 2001 2002 2003 2004 2005 2006 Jan 6,745,400 5,603,000 5,900,000 5,603,000 5,603,000 4,590,570 Feb 5,209,700 6,235,200 5,680,000 6,235,200 6,235,200 4,508,538 Mar 9,420,600 8,292,300 2,200,000 8,292,300 8,292,300 4,297,260 Apr 9,580,100 35,861,000 8,650,000 35,861,000 35,861,000 5,269,241 May 37,065,000 17,765,300 15,000,000 17,765,300 17,765,300 12,747,697 Jun 20,124,200 18,993,600 15,780,000 18,993,600 18,993,600 16,416,501 Jul 18,321,400 20,226,800 20,226,800 20,226,800 18,649,076 18,641,152 Aug 19,012,800 20,343,500 20,343,500 20,343,500 16,755,128 15,885,674 Sep 16,104,800 5,994,500 5,994,500 5,994,500 11,938,627 13,198,163 Oct 12,645,500 13,271,200 13,271,200 13,271,200 9,022,415 8,893,581 Nov 7,781,800 17,505,500 17,505,500 17,505,500 6,840,771 5,290,867 Dec 6,614,400 6,100,000 6,100,000 6,100,000 5,051,885 5,283,632 Total 168,625,700 176,191,900 136,651,500 176,191,900 161,008,302 115,022,876 Total, mgd 0.46 0.48 0.37 0.48 0.44 0.32 Average, mgd 0.43 Data from July 2003 through June 2005 was not available, therefore City staff directed WYA to use data from 2002 during this time period. The values are shown in red font. Peaking Factors Maximum day and peak hour demand factors were calculated using data provided by the City for the Turlock system. The maximum day peaking factor was developed based on a 3-year average from 2005 through 2007, as shown in Table 2. The peak hour peaking factor was developed based on a 2-year average from 2006 through 2007, as shown in Table 3. Table 2. Maximum Day Demand Peaking Factor Year Date Max Day, gpd Average Day, gpd Peaking Factor 2005 07/17/05 684,377 441,119 1.55 2006 07/23/06 757,359 315,137 2.40 2007 07/07/07 634,680 325,197 1.95 Average 1.97 ---PAGE BREAK--- West Yost Associates A-3 o:\c\418\02-07-22\wp\er\20091031ce2AttA Table 3. Peak Hour Demand Peaking Factor Year Date Peak Hour, gpm Average Day, gpm Peaking Factor 2006 07/23/06 600 219 2.74 2007 07/07/07 533 226 2.36 Average 2.55 Model Development Node elevations were automatically computed using U.S. Geological Survey Digital Elevation Models (DEM). Pipelines were assigned C-factors based on material types and age as indicated by City Operations staff, ranged from 135 to 100. The water surface elevation for all wells were modeled as fixed-grade reservoirs, with water surface elevations equal to active water pumping levels s reported in City pump tests. Well pumps were modeled with design point curves as presented in Table 4. Flow and head data points are based on observed flow and computed total dynamic head from City pump tests. Well 275 has a variable frequency drive (VFD) to control system pressure. To simulate the VFD, the pump is modeled with variable speed settings to represent the speed of the VFD, with settings based on control settings provided by the City. Wells 256 and 306 have hydropneumatic tanks to control system pressure. To simulate the hydropneumatic tanks, a tank is modeled on the discharge side of the pump station. Tanks were assumed to have a low pressure set point of 40 psi and a high pressure set point of 60 psi. The water level range in the tank was set based on these settings (e.g. 40 psi equates to a minimum water level in the tank of 92 ft and 60 psi to a tank level of 139 ft). Table 4. Well Model Characteristics Modeled with Design Point Curve Well Diameter, inches Head, feet Flow, gpm 255 6 201.50 240 256 4 210.05 250 275 6 226.60 450 306 6 213.02 210 Well pump has variable frequency drive. Well has a hydropneumatic tank. ---PAGE BREAK--- West Yost Associates A-4 o:\c\418\02-07-22\wp\er\20091031ce2AttA Demand Allocation MWH Soft H2ONet and InfoWater allow the definition of multiple demand fields at a single node to represent different use classes or demand types. Existing system demands are modeled in demand field 10. Since the area served is essentially built out, no future demands were allocated to the model. Metered Customers: While large metered customer loads are typically assigned individually to the closest model node, the Turlock service area metered non-residential demand amounts to only approximately 11 percent of the total, with no significantly large individual accounts. Therefore, metered consumption was combined and allocated with the residential unmetered component. Unaccounted-for-Water: The City has determined Unaccounted-for-Water is approximately 15 percent of total production system-wide. Unaccounted-for-Water was assumed to be uniformly lost throughout the distribution system, and therefore was combined for allocation purposes with the residential unmetered component. Unmetered Residential Customers: The bulk of the demand is by unmetered residential customers. Because the Turlock service area is currently fully developed, all nodes were assigned demands equally based on the location of the individual service area. In the northern service area, the unit demand per node is the total consumption (estimated at 69 gpm average day) divided by number of nodes or 9.9 gpm per node. The central and southern areas were calculated to have unit demands per node of 2.85 gpm and 5.79 gpm, respectively. Maximum Day and Peak Hour (see Table 4 for factors) demand sets were calculated by applying the appropriate factors to the average day demands. Fire: The Turlock water service area has no large industry or dense commercial areas. Therefore, the fire demand of 1,500 gpm was used for the entire service area. Scenarios The scenarios modeled are shown in Table 5. Table 5. Model Scenarios Scenario Description Definition AD 2001-2006 Average Day Demand Scenario Model of the 2001-2006 average day demand condition MD 2001-2006 Maximum Day Demand Scenario Model of the 2001-2006 maximum day demand condition MDFF 2001-2006 Maximum Day plus Fire Flow Scenario Model of the 2001-2006 maximum day demand plus 1,500 gpm fire flow demand condition PH 2001-2006 Peak Hour Demand Scenario Model of 2001-2006 peak hour demand condition EX_CIP Existing System Recommended CIP Scenario Model of existing system with CIP recommendations ---PAGE BREAK--- West Yost Associates A-5 o:\c\418\02-07-22\wp\er\20091031ce2AttA Data Sets The Data Sets contained in the model are shown in Tables 6 through 9. Table 6. Demand Sets Demand Set Description Definition AD 2001-2006 Average Day Demand Set Average day demand MD 2001-2006 Maximum Day Demand Set (AD x 1.82) Maximum day demand condition MDFF 2001-2006 Maximum Day w/ Fire Flows 1,500 gpm fire flow demand condition PH 2001-2006 Peak Hour Demand Set Peak hour demand condition Table 7. Pipe Sets Pipe Set Description Definition BASE Existing Pipe Set Existing system configuration EX_CIP CIP Recommendation Pipe Set Recommended CIP system configuration Table 8. Fire Flow Sets Fire Flow Set Description Definition FF1500 1,500 gpm Fire Flow at Fire Hydrant Nodes This sets up the fire flow analysis at each hydrant node Table 9. Control Sets Control Set Description Definition AD 2001-2006 Average Day Controls Existing average day demand controls MD 2001-2006 Maximum Day Controls Existing maximum day demand controls MD_FF 2001-2006 Maximum Day with Fire Flow Controls Existing maximum day demand with concurrent fire flow controls PH 2001-2006 Peak Hour Controls Existing peak hour demand controls EX_CIP Existing System CIP Controls Existing system CIP recommended controls ---PAGE BREAK--- West Yost Associates A-6 o:\c\418\02-07-22\wp\er\20091031ce2AttA Model Element Information To provide flexibility in modeling various system configurations, each modeling element was assigned a phase, as listed in Table 10 below. Each phase number corresponds to the modeling element’s system configuration. Table 10. Modeling Element Phase Numbering Convention Phase Definition 1 Existing System 2 Existing System CIP