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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 Existing and Buildout Water System for the Hickman Outlying Service Area (Hickman 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 Engineer’s Report, the City has requested West Yost Associates (WYA) to provide an individual hydraulic assessment of each of these systems, in order to evaluate the ability of existing facilities to meet current and buildout demands. The hydraulic evaluation of the Community of Hickman (Hickman) water system 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 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 635 gallons per minute (gpm) and 380 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 not sufficient to meet Peak Hour and Maximum Day demand conditions. Therefore, additional water supply is required. It is also recommended that a standby generator be installed at Well 309 to improve reliability of service in case of a power outage. Recommendations for additional water supply are outlined in the following sections. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 2 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG 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 0.25 x Maximum Day demand. Fire flow demand was established as 1,500 gpm for a 2-hour duration. Emergency storage was established as 1.00 x the average day demand. Approximately 0.40 MG of storage is required to meet existing City storage criteria under reliable pump capacity conditions. Therefore, a 0.40 MG storage tank and 1.20 mgd pump station is recommended to provide the additional storage. 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. The hydraulic model indicates that with two wells in operation, the City cannot maintain the required system pressures of 40 psi during peak flow or 20 psi residual during Maximum Day plus fire flow. Further, head losses in existing pipelines exceed the City’s criteria. In order to provide the needed service with all wells in operation, and further, to provide reliable service with the largest well of out of operation, additional supply is required. To correct these existing system deficiencies, this memo presents two potential alternatives: Alternative A: Hickman remains an independent water service area. Under this alternative, the recommended capital improvements to the existing water system are listed below and anticipated to cost approximately $6.6M, as detailed in Table 7 of this TM. Install backup generator at existing Well 309. Construct new well with a pumping capacity of at least 600 gallons per minute (gpm), with standby generator to meet peak flow demands. Install new 0.40 million gallons (MG) storage tank and associated 1.20 million gallon per day (mgd) pump station with standby power to meet storage and fire flow demands. Construct 9,400 linear feet of upsized pipelines to convey fire flow. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 3 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG Alternative B: Hickman service area is interconnected to the City of Waterford service area. Under this alternative, the recommended capital improvements are listed below and anticipated to cost approximately $4.8M, as detailed in Table 7 of this TM. Install backup generator at existing Well 309. Construct new well with a pumping capacity of at least 600 gpm, with standby generator to meet peak flow demands. Add 5,800 linear feet of new pipeline connecting the Hickman service area to the City of Waterford service area to meet fire flow demands. Construct 9,400 linear feet of upsized pipelines to convey fire flow. Alternative A requires more equipment and has a higher cost than Alternative B. However, despite the higher cost, Alternative A is recommended because it allows the City of Modesto’s water system in Hickman to remain independent of the water system in the City of Waterford. Alternative B would require negotiations with the City of Waterford to secure additional land for a suitable well location. 1.4 Buildout System The existing Hickman water system is approximately 90 percent built out and has some vacant and undeveloped infill areas shown on Figure 1. The total area of the planned development land use is approximately 18 acres. In the previous hydraulic evaluation of the Hickman water system in 2005, this area was designated as road and railroad property; however projected use has changed to primarily residential property. The additional infill development is anticipated to increase the Hickman service area demands by approximately 0.05 mgd (36 gpm) to a total of 0.29 mgd (203 gpm). The existing system recommendations discussed above are adequate to serve projected buildout demand. Therefore, no additional capital improvements are required for buildout of the Hickman system. 2.0 INTRODUCTION In 2002, the City contracted with WYA to provide engineering services to assist in the conversion, updating, enhancement and calibration of a water system hydraulic model for the Hickman water system. Using the methodology described in Attachment A of this TM, WYA developed a hydraulic network analysis model of the Hickman water distribution system to allow computer simulations of various demands and flow conditions. The 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\20091031ceG1AppG In order to create a hydraulic network analysis model representative of the Hickman water system, WYA completed the steps listed below: Used shapefiles exported from the City of Modesto’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 Hickman water system. Evaluated 2002 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. Since the development and calibration of the hydraulic model in 2002, approximately 800 feet of pipeline on Elma Street has been upsized from 4-inch diameter to 8-inch diameter pipe. Additionally, system demand has increased and infill areas previously identified for road and railroad are now planned to support residential infill. The 2002 model has been updated to reflect these changes in system infrastructure and demands. This TM presents the updates performed, model results, and recommended facility improvements. This memo is organized as follows: Service Area Existing Water System Hickman Hydraulic Model Existing Water Supply System Evaluation & Recommendations Buildout Water Supply System Evaluation & Recommendations 3.0 SERVICE AREA The community of Hickman is located approximately 14 miles east of the City of Modesto and south of Highway 132 and the City of Waterford. The Hickman water system serves approximately 460 residents, and encompasses a service area containing approximately 146 acres. This service area is primarily residential, and is approximately 90 percent built out. The Hickman service area was originally provided with water service by the Del Este Water Company; in the mid 1990’s, the City of Modesto acquired the Del Este system and began providing water service to Hickman. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 5 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG 4.0 EXISTING WATER SYSTEM The Hickman water system includes two existing wells, no storage tanks, and approximately 17,000 linear feet of pipeline. Existing Hickman pipelines vary in size from 4-inches to 10-inches in diameter and are comprised of cast iron or polyvinyl chloride pipe. Currently, there are no interconnections with any other water systems. However, the City of Waterford is located approximately 1.1 miles from Hickman. Interconnecting these two independent water systems could be explored as a means for additional supply. 4.1 Wells The Hickman water system is solely supplied by groundwater from two existing wells; Figure 1 shows the locations of Wells 272 and 309. Groundwater is disinfected by chlorine addition at the wellhead, and then discharged directly into the distribution system. In addition, granulated activated carbon (GAC) treatment for hydrogen sulfide occurs upstream of disinfection at Well 309. Well 272 is equipped with a backup power supply. Well characteristics are summarized in Table 1. Table 1. Well Characteristics(a) History Pump Data Well Construction Details Well No. Address Year Drilled Rated Pump Capacity (at 60 psi), gpm(d) Rated Hp Standby Power Treatment System Casing Diameter (inches) Gravel Packed Depth of Annular Seal Casing Depth Perforated From/To Total Depth 272 13127 Hickman Rd 1961 360 30 Yes None 14 No NP(c) 104 None 332 309 6th Street & Montpelier 1994 450 40 No GAC(b) 16 No 92 160 None 160 Based on information provided by the City. GAC = Granulated Activated Carbon NP = Not Provided by City Based on data collected upon well completion Pump efficiency tests were performed on both wells in December 2007. Well 272 is only pumping at 56 percent of its rated capacity. This well is 47-years old, and is near the end of its expected useful life of 35 to 50 years (useful life changes depending on site specific hydrogeologic conditions). The production decrease observed in Well 272 is probably due to incrustation of the well screens, integrity of the well casing, and other age-related matters. However, Well 272 is not recommended for replacement at this time because other recommendations, such as the new well, will provide sufficient capacity for this system. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 6 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG Results of the pump efficiency tests are presented 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 272 12/21/07 30 201 95 99 60 12.06 309 12/21/07 40 449 94 96.5 65 27.97 Static and Pumping Levels indicate depth to water measurements from reference point elevations. Table 3 provides a summary of the total groundwater production of each individual well in 2005, and Figure 2 provides a graphical summary of this data. Table 3. Summary of Hickman Service Area Production in 2008a) Well 272 Well 309 Month Gallons MG gallons MG January 1,458,608 1.46 827,921 0.83 February 1,445,955 1.45 815,409 0.82 March 2,875,663 2.88 1,162,968 1.16 April 4,663,265 4.66 1,582,883 1.58 May 5,639,610 5.64 2,234,687 2.23 June 4,744,690 4.74 4,675,243 4.68 July 5,052,547 5.05 4,796,866 4.80 August 5,205,861 5.21 4,464,121 4.46 September 4,650,205 4.65 2,823,416 2.82 October 3,479,365 3.48 1,777,412 1.78 November 1,855,214 1.86 1,037,594 1.04 December 1,494,811 1.49 869,078 0.87 Subtotal 42,565,792 42.57 27,067,598 27.07 Total Annual Supply 69.64 Data provided by the City of Modesto on September 4, 2009, from the file well flow totals 2002 to present.xls”. 4.2 Wellhead Treatment A wellhead treatment facility comprised of granulated activated carbon filtration is currently in use at Well 309. The system has operated since the late 1990s to remove hydrogen sulfide and eliminate associated taste and odor issues. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 7 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG 4.3 Storage There are currently no storage facilities or pumping plants (other than the well pumps) in the Hickman service area. 4.4 Pipelines General knowledge of the Hickman pipeline main locations and material type was gained through discussion with City Operations staff. Pipelines within the service area range from 4- to 10-inches in diameter, and are constructed of cast iron or polyvinyl chloride (PVC), with PVC pipes being newer than cast iron pipes. About 90 percent of the pipelines are approximately 30 to 40 years old, with the remaining 10 percent installed more recently (post 1990). 5.0 HICKMAN HYDRAULIC MODEL In 2002, WYA developed a hydraulic model of the Hickman water service area using H2ONET hydraulic modeling software. This model has been updated to reflect 2005 demands. The model represents the current system infrastructure, well characteristics and peaking factors through 2007. A summary of assumptions, criteria, and model components is included in Attachment A of this TM. 6.0 EXISTING WATER SUPPLY SYSTEM EVALUATION AND RECOMMENDATIONS 6.1 Overview This section presents findings from the hydraulic evaluation of Hickman’s existing water distribution system and its ability to meet the City of Modesto’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 Hickman system were estimated and allocated based on the methodology described in Attachment A. Based on production data provided by the City from 2003 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 5-year average from 2003 through 2007. The Peak Hour peaking factor was developed based on a 2-year average from 2006 through 2007. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 8 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG Table 4. Water Demand Peaking Factors 2005 Demands Demand Condition Peaking Factor(a) mgd gpm Average Day – 0.24 167 Maximum Day 2.27 x Average Day 0.55 380 Peak Hour 3.79 x Average Day 0.91 635 Based on available water production data for the Hickman service area. Peaking factors were provided by the City as Max-Day Peak Factor.xls on 7/31/08 and Peak-hour tabulation - Outlying Areas.xls on 8/1/08. 6.3 Pumping Capacity Evaluation The Hickman service area is supplied exclusively by groundwater that is pumped from two existing production wells. Table 5 provides a summary of recent pump flow testing for each operational well, and indicates a total existing supply capacity of 620 gpm. However, for water supply planning purposes, this groundwater supply (groundwater pumping capacity) must be reduced to account for 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. This scenario provides an allowance for mechanical breakdowns, maintenance, or other operational issues. As shown on Table 5, the current total Reliable Pumping Capacity of 190 gpm (with Well 309 out of service) is not sufficient to meet existing Maximum Day or Peak Hour demands of 380 gpm and 635 gpm, respectively. Further, with Well 309 in operation, the total available pumping capacity of 620 gpm is still not sufficient to meet the existing Peak Hour demand of 635 gpm. Therefore, additional water supply is required. Recommended Alternatives for this added supply are presented later in this TM. In addition to added water supply, it is recommended that a standby generator be installed at Well 309 to improve reliability of service in case of a power outage. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 9 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG Table 5. Summary of Existing System’s Supply Facilities Well Pump Name Efficiency, percent(a) Standby Power Existing Capacity, gpm(b) Existing Maximum Day Demand, gpm Existing Peak Hour, gpm 272 47.50 Yes 190 – – 309 36.27 No 430 – – Total Capacity 620 380 635 Total Reliable Capacity 190 380 635 Based on pump efficiency testing from December 2007. Pump tests conducted by City operations staff. Based on pump capacity testing from August 2007. Pump tests conducted by City operations staff. 6.4 Storage Capacity Evaluation Criteria has been defined by WYA for the City in 2003 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: 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 x average day demand. The Hickman 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. This dependence on the groundwater basin for storage presents a reliability issue; there is no allowance for possible contamination or other scenario that renders a portion of the basin unavailable. As shown on Table 6, approximately 0.40 MG of tank storage is required in the existing Hickman water system to meet existing City storage criteria. This volume was calculated using a Reliable Pumping Capacity scenario with Well 309 is out of service. Increased storage capacity may be obtained by either constructing a 0.40 MG storage tank and associated 1.2 MGD pump station or constructing a new 600 gpm well. However, approximately 0.02 MG of tank storage is still required if a new well is constructed. Therefore, both Alternatives are recommended because the storage tank will provide additional storage capacity, and the new well will provide additional supply capacity to meet fire flow conditions. The locations of the proposed facilities are for planning purposes only and should be developed further in future pre-design studies. Fire flow conditions are discussed further below. ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 10 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG Table 6. Summary of Required Above Ground Storage Storage Component Component Detail Storage without New Well, MG Storage with New Well(a), MG Operational 0.25 x Maximum Day demand 0.14 0.14 Fire 1500 gpm for 2 hours 0.18 0.18 Emergency 1.00 x average day demand 0.24 0.24 Subtotal 0.56 0.56 Groundwater Credit 60% reliable production capacity (0.16)(b) (0.54)(c) Total Storage Required 0.40 0.02 New well assumed to have a production capacity of 600 gpm. Sixty percent of existing reliable groundwater pumping capacity (without Well 309). Sixty percent of existing reliable groundwater pumping capacity (without New Well). 6.5 Existing Distribution System Evaluation The hydraulic model identified areas of Hickman’s existing system in which minimum pressure could not be maintained, or where velocities and/or head losses were found to exceed City design standards. A discussion is provided in the following sections. 6.5.1 Peak Hour Demand Conditions The Peak Hour demand for the City’s potable water distribution system under existing 2005 conditions is approximately 0.91 mgd (635 gpm). This Peak Hour demand condition was simulated in the model. Results indicated that the existing distribution system cannot reliably deliver these demands under the City’s minimum pressure criteria of 40 psi, even with both wells in service (see Figure This analysis also indicated that head losses in existing pipelines exceed the City’s criteria of < 7 feet per 1,000 feet (ft/kft); however, flows were able to meet the velocity criteria of < 7 feet per second (fps). The pipelines that did not exceed both headloss and velocity criteria are not recommended to be rehabilitated or upsized. However, other upsized pipelines are required in order to address pressure deficiencies. In order to remedy the pressure deficiency shown in Figure 3, WYA recommends that the City install a new well with a pumping capacity of 600 gpm and upsize pipelines throughout the system (see Figure 6.5.2 Maximum 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 Hickman is 1,500 gpm for a two hour duration. Based on the hydraulic analysis of the Maximum Day plus fire flow demand condition, Hickman’s existing water system cannot maintain a minimum residual system pressure of 20 psi in any areas of the Hickman service area, even with both existing wells operating (see Figure ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 11 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG Similar to the Peak Hour demand condition, the reason for the pressure deficiency is a lack of supply. The total pumping capacity of both existing wells is only 620 gpm, which is less than half of the required 1,500 gpm fire flow. However, with the addition of the previously recommended storage tank, then the additional construction of a new 600 gpm well is recommended to meet the max day with fire flow demand conditions. Constructing a storage tank and well is recommended over constructing two wells because the construction costs for a tank and well is more economical than the construction costs for two wells. Alternatively, a new connection with the City of Waterford can also provide additional water supply. These two alternatives are outlined below: Alternative A: Construction of a 0.40 MG storage tank with associated 1.15 mgd booster pump station and back up generator that will be capable of supplying the additional required flow, and the addition of a new 600 gpm well; or Alternative B: A new interconnection to the City of Waterford water service area to the north, and the addition of a new 600 gpm well. Due to the increased flow required to be distributed throughout the water system under either Alternative, approximately 55 percent of the existing pipelines will need to be upsized to deliver the water to hydrant locations. These two improvement Alternatives are shown in Figure 6 and detailed in Table 7. Under Alternative A, a new 0.40 MG storage tank with associated 1.20 mgd booster pump station must be constructed in addition to the proposed new well and upsized pipelines. With these system requirements, the fire flow with concurrent Maximum Day demand condition can be met while maintaining the minimum required residual pressure of 20 psi, as shown in Figure 7. Under Alternative B, the Hickman service area could be interconnected to the City of Waterford water service area to provide additional supplies and to increase system pressures in the Hickman service area (see Figure Under this hydraulic scenario, a flow of approximately 1,300 gpm would be provided from the City of Waterford’s water system into the Hickman water system; this additional supply would be used to meet Maximum Day plus fire flow demand, with Well 309 out of service. In addition to the benefit of providing additional supply to the Hickman service area for the Maximum Day demand plus fire flow condition, this interconnection would increase the reliability and flexibility of both systems in the event that water system facilities need to be taken out of service for routine maintenance or emergency conditions. Also, since Hickman has experienced water quality issues Well 273 was abandoned due to the presence of uranium, and Well 309 requires additional treatment to remove hydrogen sulfide), this Alternative would help provide additional system redundancy to the Hickman system if one well must be taken out of service due to water quality issues. ---PAGE BREAK--- CIP CIP Unit Cost(b) Alternative A Cost(c) Alternative B Cost(d) ID Reason Item Unit Quantity Pipelines FF01 Fireflow Along Montpelier Road from Lake Road to Emma Lane 12-inch lf 2,360 136 322,225 322,225 FF02 Fireflow Along Lake Road from Montpelier Road to I Street 8-inch lf 800 101 80,117 80,117 FF03 Fireflow Along I Street from Lake Road to 4th Street 8-inch lf 1,030 101 103,187 103,187 Fireflow Along I Street from Lake Road to 4th Street 8-inch lf 760 101 76,620 76,620 FF04 Fireflow Tie-In between two north-south mains along Montpelier Road 10-inch lf 20 123 2,308 2,308 FF05 Fireflow Along Davis Street from Hickman Road to Elma Street 8-inch lf 530 101 53,053 53,053 FF06 Fireflow Along Kim Street from Hickman Road to Lorenzo Street & along Kim Court & Lorenzo Street 8-inch lf 1,310 101 131,930 131,930 FF07 Fireflow Along Hickman Road from Lake Road to Kim Street 10-inch lf 1,040 123 127,339 127,339 FF08 Fireflow Along 6th Street from Elma Street to Well 309 10-inch lf 810 123 99,373 99,373 FF09 Fireflow Along Lake Road from Hickman Road to Well 272 10-inch lf 310 123 37,860 37,860 HL10 Headloss Along Lake Road from Well 272 to Montpelier Road 12-inch lf 380 136 51,364 51,364 Supply Connection from Waterford service area to Hickman service area 12-inch lf 5,820 136 794,032 Storage Tank Supply 0.40 MG Storage Tank Supply 72 bhp Pump Station with backup generator and SCADA Well Supply New Well with 600 gpm pump, backup generator, and SCADA ls 1 1,333,000 1,333,000 1,333,000 Well Backup Generator Supply Well 309 ls 1 133,000 133,000 133,000 Subtotal (Overall Program) 4,418,000 3,212,000 50% Contingency & Other Costs 2,210,000 1,606,000 Total Estimated CIP Construction Cost 6,628,000 4,818,000 Does not include site specific facilities. curves, construction cost guidelines and similar construction projects. Option A includes the construction of a new 0.40 MG storage tank, pump station and back up generator and SCADA. Table 7. Recommended CIP Program for Hickman Existing Water System All unit prices presented in March 2010 dollars (ENR Construction Index = 9728.17). Unit prices based on combination of cost Option B includes the construction of the inter-connection pipeline between the Waterford service area and Hickman service area. Does not include costs to attend meetings with City of Waterford to discuss, negotiate and obtain approval to install proposed intertie. ls 1,867,000 West Yost Associates o:\c\418\02-07-22\wp/\er\20091031ceG3 T7 Last Revised: 09/19/08 City of Modesto Engineer's Report Appendix G Hickman TM ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 13 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG 7.0 RECOMMENDED WATER SYSTEM IMPROVEMENTS Based on the evaluations completed for the Hickman water system, there is a need for specific water facility improvements throughout Hickman’s overall service area. An overview of the recommended facilities is provided on Figure 6. A summary of the recommended improvements is provided below. 7.1 Existing System Improvements The recommended improvements to Hickman water system ensure that reliable service can be provided to existing users in a manner that meets the City’s system design criteria. Alternative A is recommended to provide increased reliability to the Hickman water system. Under Alternative A, the recommendations include: Install backup generator at Well 309, Construct new well with a pumping capacity of at least 600 gpm, with standby generator, Construct new 0.40 MG storage tank and associated 1.20 mgd pump station with standby power, and Construct 9,400 linear feet of upsized pipelines. Under Alternative B, the recommendations include: Install backup generator at Well 309, Construct new well with a pumping capacity of at least 600 gpm, with standby generator, Add 5,800 linear feet of new 12-inch diameter pipeline connecting the Hickman service area to the City of Waterford service area, and Construct 9,400 linear feet of upsized pipelines. Locations of the recommended improvements are shown on Figure 6 and detailed in Table 7. 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 or replace aging water system infrastructure over time. The decision to repair or replace existing facilities should be based primarily on facility condition. Pipelines that have experienced corrosion but have retained adequate structural integrity may often be repaired instead of replaced. Preventive maintenance is usually more cost effective and less disruptive than replacement, maximizes the useful life of the pipeline, and thereby optimizes lifecycle cost. Pipes that have experienced extensive corrosion and do not have adequate structural integrity should be replaced. In addition, the smaller diameter pipelines throughout the ---PAGE BREAK--- Technical Memorandum March 30, 2010 Page 14 West Yost Associates o:\c\418\02-07-22\wp\er\20091031ceG1AppG service area should be replaced with 8-inch diameter pipelines to provide additional supply and fire flow demand capacity. A system-wide condition assessment is also recommended to evaluate existing pipe conditions and to develop a prioritized replacement program. The program may involve internal and external corrosion evaluations to determine when to replace certain pipelines. 8.0 CAPITAL COSTS OF RECOMMENDED IMPROVEMENTS The estimated probable capital costs for the recommended water system improvements to serve Hickman’s existing condition are presented in Table 7. 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. 9.0 EVALUATION OF BUILDOUT WATER SUPPLY SYSTEM 9.1 Overview This section presents the hydraulic evaluation of the Hickman water distribution system and its ability to meet City of Modesto’s recommended water system operational criteria under buildout demand conditions. The existing water distribution system was evaluated under Maximum Day, Peak Hour and Maximum Day with concurrent fire flow demand conditions. 9.2 Potable Water Demands Although the Hickman water service area is approximately 90 percent built out, there will be some additional water demands on the system as buildout is completed. The 18 remaining acres available for buildout are designated as residential development; after development is completed, average day demand will increase by approximately 0.05 mgd. Therefore, the total future potable water demand under average day demand conditions will be 0.29 mgd. Using the same peaking factors of 2.27 and 3.79 that were applied to the evaluation of existing system capacity, demands for Maximum Day and Peak Hour flows are 0.66 mgd and 1.11 mgd, respectively. 9.3 Buildout Distribution System Evaluation The same analyses and calculations that were conducted to evaluate the ability of the system to meet current demands were applied for the analysis of buildout conditions. Based on these analyses, buildout demands can be adequately met with construction of the previously recommended existing system improvements. However, to ensure adequate service for the Hickman service area customers, the City should consider developing a rehabilitation and replacement program for the service area’s aging pipelines. ---PAGE BREAK--- ---PAGE BREAK--- West Yost Associates o:\c\418\2-07-22\wp\er\20091031ceG4 F2 Last Revised: 08/07/08 City of Modesto Engineer's Report Appendix G Hickman TM Figure 2. Town of Hickman - Production by Well (2008) 0 2,000,000 4,000,000 6,000,000 8,000,000 10,000,000 12,000,000 January February March April May June July August September October November December Month Production (Gallons) Well 272 Well 309 Notes: - Data based on well production information in Table 3. ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ATTACHMENT A Development of Hickman’s Hydraulic Model ---PAGE BREAK--- West Yost Associates A-1 o:\c\418\02-07-22\wp\er\20091031ceG2 AttA ATTACHMENT A. DEVELOPMENT OF HICKMAN’S HYDRAULIC MODEL WYA developed a hydraulic model for the City of Modesto (City) of the Hickman Service Area (Hickman) using MWH Soft’s H2ONET hydraulic modeling software. The distribution system depicted in the City-provided AutoCAD file 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 Hickman’s 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, values (C-factors), were assigned based on age (if available) and pipe material. Pump station piping configurations, performance curves, and motor size information were acquired from “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). Peaking Factors Maximum day and peak hour demand factors were calculated using data provided by the City. The maximum day peaking factor was developed based on a 5-year average from 2003 through 2007, as shown in Table 1. The peak hour peaking factor was developed based on a 2-year average from 2006 through 2007, as shown in Table 2. ---PAGE BREAK--- West Yost Associates A-2 o:\c\418\02-07-22\wp\er\20091031ceG2 AttA Table 1. Maximum Day Demand Peaking Factor Year Date Max Day, gpd Average Day, gpd Peaking Factor 2003 08/09/03 482,123 232,611 2.07 2004 07/15/04 470,481 235,629 2.00 2005 07/29/05 465,064 241,204 1.93 2006 06/25/06 564,157 173,321 3.25 2007 07/06/07 394,938 188,221 2.10 Average 2.27 Table 2. Peak Hour Demand Peaking Factor Year Date Peak Hour, gpm Average Day, gpm Peaking Factor 2006 06/25/06 563 120 4.68 2007 07/06/07 379 131 2.90 Average 3.79 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 and range from 135 to 100. The water surface elevation for both existing wells were modeled as fixed-grade reservoirs, with water surface elevations equal to active water pumping levels as reported in City pump tests. Well pumps were modeled with design point curves as presented in Table 3. Flow and head data points are based on observed flow and computed total dynamic head from City pump tests. Both wells have variable frequency drives (VFDs) to control system pressure. To simulate these VFD’s, pumps are modeled with different speed settings to match system pressure settings provided by the City. Table 3. Well Model Characteristics Modeled with Design Point Curve Well Diameter, in Head, ft Flow, gpm 272 6 237.6 201 309 8 244.2 449 ---PAGE BREAK--- West Yost Associates A-3 o:\c\418\02-07-22\wp\er\20091031ceG2 AttA 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 Field 10 and incremental future demands are modeled in Field 9. Existing System Demands Metered/Unmetered Residential Customers: The Hickman Service Area is mainly composed of residential land use. Because Hickman is close to fully developed, all parcels were assigned equal demand. The unit demand per parcel is the total consumption (0.24 mgd average day) divided by number of parcels (183), or 0.91 gpm per parcel. Parcels, and their associated demand, were aggregated to the nearest model junction nodes to develop the base average day demand set. 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. Fire: The Hickman Service Area has mainly residential land use. There are no other significant amounts of other land uses. A fire demand of 1,500 gpm for a 2-hour duration was used in this analysis for all hydrants in the system. Future Demands Approximately 18 acres of in-fill development is anticipated in the Hickman service area, with an associated average daily demand of 30 gpm. Maximum day and peak hour (see Table 4 in the TM for factors) demand sets were calculated by applying the appropriate factors to the average day demands. These demands were assigned in demand field 9 in the model demand table, with an associated designation of ‘Infill.’ Scenarios The scenarios modeled are shown in Table 4. Table 4. Model Scenarios Scenario Description Definition EX_AD Average Day Scenario Model of average day demand condition EX_MD Maximum Day Scenario Model of maximum day demand condition EX_MDFF Maximum Day plus Fire Flow Scenario Model of the maximum day demand plus 1,500 gpm fire flow demand condition EX_PH Peak Hour Scenario Model of peak hour demand condition EX_CIP Recommended Pipe Replacements for CIP Model of maximum day plus fire flow demand condition with recommended improvements to meet the minimum design criteria CIP_PHBO Recommended Pipe Replacements for CIP Model of future peak hour demand condition with recommended improvements to meet the minimum design criteria ---PAGE BREAK--- West Yost Associates A-4 o:\c\418\02-07-22\wp\er\20091031ceG2 AttA Data Sets The Data Sets contained in the model are shown in Tables 5 through 8. Table 5. Demand Sets Demand Set Description Definition EX_AD Average Day Demand Set Existing average day demand condition EX_MD Maximum Day Demand Set Existing maximum day demand condition EX_MDFF Maximum Day w/ Fire Flows Existing maximum day plus fire flow demand condition EX_PH Peak Hour Demand Set Existing peak hour demand condition BO_PH Peak Hour Demand Set Buildout peak hour demand condition Table 6. Pipe Sets Pipe Set Description Definition BASE Existing Water System Existing system configuration PH_CIP CIP Recommendations for Peak Hour demand Recommended improvements for peak hour demands EX_CIP CIP Recommendations Recommended system configuration improvements Table 7. Fire Flow Sets Fire Flow Set Description Definition FF_1500 Fire Flow at Hydrant Nodes Includes the fire flow required at each hydrant node Table 8. Control Sets Control Set Description Definition EX-AD Average Day Controls Existing average day demand controls EX-MD Maximum Day Controls Existing maximum day demand controls EX-MDFF Maximum Day with Concurrent Fire Flow Controls Existing maximum day with concurrent fire flow demand controls EX-PH Peak Hour Controls Existing peak hour demands controls CIP_PH Peak Hour Controls Existing peak hour demand controls with CIP improvements EX-CIP Existing CIP Controls Existing system CIP recommended controls ---PAGE BREAK--- West Yost Associates A-5 o:\c\418\02-07-22\wp\er\20091031ceG2 AttA Calibration WYA attempted to perform a very limited calibration of the hydraulic model based on data from a single hydrant test provided to WYA by the City. Unfortunately, this data was not adequate to determine a pipeline “C-factor.”