MASTER WATER SYSTEM DESIGN REPORT DESERT TRAILS

Transcription

1 MASTER WATER SYSTEM DESIGN REPORT FOR DESERT TRAILS SURPRISE, ARIZONA Prepared for: HE Capital Fox Trails, LLC 2850 E. Camelback Road Suite 110 Phoenix, Arizona st Submittal February, ND Submittal September, RD Submittal December, th Submittal February, 2010 Prepared by:

2 MASTER WATER SYSTEM DESIGN REPORT FOR DESERT TRAILS TABLE OF CONTENTS 1. INTRODUCTION Project Location & General Description Existing Studies EXISTING WATER SYSTEM CONDITIONS WATER SUPPLY FACILITY DESIGN CRITERIA Potable Water Drinking Water Quality Wells Storage Reclaimed Water Reclaimed Water Supply Reclaimed Water Facility System Design DEMAND DESIGN CRITERIA Service Area Land Use/ Population Projections On-Site Potable Service Area Off-Site Potable Service Area Potable Water Demand Criteria Proposed Potable System Demand Criteria Reclaimed Water Demand Criteria WATER SYSTEM MODELING WSLG and Ultimate Water Distribution System Desert Trails Water Distribution System Network Analysis Modeling Scenarios Desert Trails Potable Water Distribution Model Ultimate Condition Potable Water Distribution Model Desert Trails Reclaimed Water Distribution Model Desert Trails Water Transmission Model PROPOSED CONDITIONS Potable Water and Reclaimed Water Water Supply Transmission Lines Storage Facilities Distribution Lines Booster Stations and Pressure Zone SYSTEM MODEL & RESULTS Potable Water Distribution System Well Delivery System i

3 7.3 Reclaimed Water Transmission System Reclaimed Water Distribution System CONCLUSIONS REFERENCES APPENDICES Figures...A Tables Desert Trails Potable Water Demand Calculations...B Desert Trails Reclaimed Water Demand Calculations...B Desert Trails Water Storage and Well Production Requirements...B Desert Trails Booster Pump Requirements...B Desert Trails Potable Water Distribution System Modeling Output... C Ultimate Condition Potable Water Distribution System Modeling Output... D Desert Trails Reclaimed Water Distribution System Modeling Output... E Desert Trails Water Transmission System Modeling Output... F Regulated Drinking Water Contaminants... G WSLG Master Water Study Maps Ultimate Potable Water Distribution System...H WSLG Potable Water Distribution System...H Well Transmission System/Well Locations...H Reclaimed Water Transmission System...H Reclaimed Water Distribution System...H Letter Report... I Report Comments Response Letters... J Plates... K FIGURES Figure 1...Location Map Figure 2... Land Use Map Figure 3...Development Summary Figure 4... Phase Map Figure Preliminary Water Campus Storage Requirements Figure Preliminary Water Campus Layout Figure Proposed Arterial Utility Locations Figure Proposed Arterial Utility Locations Figure 7... Preliminary Water Distribution Infrastructure Phasing Figure 8...Preliminary Water Transmission Infrastructure Phasing ii

4 TABLES Table 1 Drinking Water Maximum Contaminant Levels... 4 Table 2 Well Design and Performance Guidelines... 5 Table 3 Potable Water Storage Criteria... 5 Table 4 Reclaimed Water Storage Requirements... 5 Table 5 IWMP Potable Water Demand Factors... 7 Table 6 Potable Water Peaking Factors... 7 Table 7 Fire Flow Criteria... 7 Table 8 IWMP Reclaimed Water Demand Factors... 8 Table 9 Reclaimed Water Peaking Factors... 8 Table 10 City of Surprise Water System Design Criteria... 9 Table 11 Desert Trails Potable Water Well Calculations Table 12 Desert Trails Reclaimed Water Well Calculations Table 13 Desert Trails Combined Water Well Calculations Table 14 Desert Trails Storage Requirements Table 15 Pressure Zone Boundaries and HGLs Table 16 Potable Booster Pump Station Requirements Table 17 Reclaimed Water Booster Pump Station Requirements Table 18 Combined System Booster Pump Station Requirements Table 19 Desert Trails Potable Distribution System Model Results Table 20 Ultimate Condition Potable Distribution System Model Results Table 21 Desert Trails Transmission Pipe Model Results Table 22 Desert Trails Reclaimed Distribution System Model Results PLATES Plate 1 Plate 2 Plate 3 Plate 4... Desert Trails Potable Distribution System... Ultimate Condition Potable Distribution System... Desert Trails Reclaimed Distribution System... Desert Trails Water Transmission System iii

5 LIST OF ABBREVIATIONS ADEQ Arizona Department of Environmental Quality ADWR Arizona Department of Water Resources AZPDES Arizona Pollutant Discharge Elimination System CAP Central Arizona Project CAWCD Central Arizona Water Conservation District City City of Surprise COG Council of Governments du/acre dwelling units per acre EDU equivalent dwelling unit fps feet per second GIS geographical information systems gpad gallons per acre per day gpcd gallons per capita per day gpd gallons per day gpd/du gallons per day per dwelling unit gpm gallons per minute HOA Homeowner's Association IWMP Integrated Water Master Plan LDR Low Density Residential MDR Medium Density Residential Zoning MU Mixed-Use Zoning PAD Planned Area Development PVC Polyvinyl chloride WSLG West Surprise Landowners Group MAG Maricopa Association of Governments MCESD Maricopa County Environmental Services Department NPDES National Pollutant Discharge Elimination System SPA special planning area SRP Salt River Project WRF water reclamation facility WS water storage WSF water supply facility iv

6 Master Water System Design Report For Desert Trails City of Surprise, Maricopa County, Arizona 1. INTRODUCTION 1.1 Project Location & General Description The Desert Trails (formerly Fox Trail) project is an 890 acre master planned development that primarily consists of single-family residential uses. The development is located within Sections 13 & 24, Township 4 North, Range 3 West of the Gila and Salt River Base and Meridian, City of Surprise, Maricopa County, Arizona. The site is located within the City of Surprise and Special Planning Area 3 (SPA 3). The site is bounded on the north by proposed Pinnacle Peak Road, on the west by proposed 219 th Avenue, and on the east by proposed 211 th Avenue with proposed Deer Valley Road splitting the site. The project location can be found on Figure 1. The tract is currently un-developed and consists of vegetation typical of the Lower Colorado River Valley Sonoran Desertscrub region. The site generally consists of an approximate 1% slope from north to south and west to east. The benchmarks utilized for this project are: Benchmark #1: The Northeast Corner of Section 13, T4N, R3W 3 Maricopa County BC 0.4 DN Stamped T4N R3W R2W S12 S7 S13 S RLS Elevation = (NAVD 88 Datum) USPLSS Point Number Z1 Benchmark #2: The Northwest Corner of Section 13, T4N, R3W 2 Maricopa County AL Cap FL Stamped T4N R3W S11 S12 S14 S RLS Elevation = (NAVD 88 Datum) USPLSS Point Number M Desert Trails Master Water System Design Report Page 1

7 1.2 Purpose of Report The purpose of this Master Water System Design Report is to define the potable and reclaimed water demands associated with the proposed Desert Trails project and model these demands to ensure that all proposed infrastructure has been adequately sized, so that the Desert Trails development may function with an independent water distribution system. This report addresses two scenarios of development. The first scenario addresses the requirements to support the Desert Trails project independent of other regional development. The second scenario addresses the compatibility of the Desert Trails system to that of the ultimate build out of the City of Surprise SPA 3 system. This report will serve to support the Desert Trails Planned Area Development Amendment (PADA) Zoning Case and subsequent Preliminary Plats for the project. 1.3 Existing Studies The development is a participant in the West Surprise Landowners Group (WSLG), a consortium of landowners with developments located within SPA 3 in the City of Surprise, Arizona. The WSLG has produced the Master Water Study for the West Surprise Landowners Group (WSLG), Special Planning Area 3 in Surprise, Arizona, dated October 2006, as a means of identifying the necessary water and reclaimed water infrastructure for the WSLG developments. The WSLG Master Water Study serves as an amendment to the City of Surprise Water Infrastructure Master Plan, dated June 2004, which identified the necessary water infrastructure for development to occur within SPA 3, as well as the other planning areas within the City s jurisdiction, according to the City of Surprise General Plan The WSLG Master Water Study has also been approved by the City of Surprise and therefore serves as the basis for this analysis. Desert Trails Master Water System Design Report Page 2

8 1.4 Design Requirements Desert Trails shall be designed and constructed in accordance with the following guidelines: Water Guidelines and Standards, City of Surprise, June 8, City of Surprise Engineering Development Standards, February 2008 Integrated Water Master Plan Water Resources, City of Surprise, November 2008 Integrated Water Master Plan Water Infrastructure, City of Surprise, July 2009 "Uniform Standard Specifications for Public Works Construction," Maricopa Association of Governments, Arizona Administrative Code (A.A.C.) 5, Article 5, Section R Arizona Department of Environmental Quality, Engineering Bulletin No. 10, Guidelines for the Construction of Water Systems. 2. EXISTING WATER SYSTEM CONDITIONS The site is not currently being served by any City of Surprise water infrastructure. As outlined in the WSLG Master Water Study, several of the proposed developments within SPA 3 have planned for water infrastructure, but under the current economic conditions many of these plans have been placed on hold. 3. WATER SUPPLY FACILITY DESIGN CRITERIA 3.1 Potable Water Drinking Water Quality Although no drinking water quality analysis shall be performed as part of this report, the purpose of this section is to define the drinking water quality standards for the Desert Trails development. Per the IWMP, the drinking water standards shall be established based upon the state and federal regulatory agency requirements. The more stringent criteria of the most current State of Arizona Drinking Water standards Desert Trails Master Water System Design Report Page 3

9 or the most current Federal Primary Drinking Water standards shall govern as the City of Surprise criteria. Per Title 18, Chapter 4 of Arizona s Safe Drinking Water code, the EPA s National Primary Drinking Water Standards has been adopted as the maximum standards. The City of Surprise has assigned a number of maximum values to contaminants not addressed by the state or federal agencies. These assigned values, as well as the typical maximum values for contaminants typically encountered in the project region, may be seen below in Table 1. Please note that some of the maximum contaminant levels from the 2006 City of Surprise Water Guidelines and Standards have been revised as part of the Integrated Water Master Plan Water Resources Master Plan. These contaminants have been identified below in Table 1. A full list of regulated contaminants may be found in Appendix G. Table 1 Drinking Water Maximum Contaminant Levels Contaminant Name Arizona Department of Environmental Quality Contaminant Code Maximum Contaminant Level (MCL) *Alkalinity mg/l **Arsenic mg/l **Copper mg/l * Escherichia Coli CFU/100ml ** Fluoride mg/l * Hardness, Calcium (CaCO3) mg/l ** Lead mg/l ** Nitrate (as N) mg/l ** Nitrite mg/l * ph * Sodium mg/l * Sulfate mg/l * Temperature deg/c *Total Coliform CFU/100ml * Total Dissolved Solids mg/l * Designates a maximum value assigned by the City of Surprise. ** Designates a maximum value revised through the - Integrated Water Master Plan Water Resources Master Plan Wells The final well site design shall be executed as part of the final improvement plans and will be performed in accordance with the 2006 City of Surprise Water Guidelines and Standards. The total required number of wells shall be designed to meet the Maximum Day Demand with the largest well out of service. Desert Trails Master Water System Design Report Page 4

10 Production Capacity Firm Capacity Table 2 Well Design and Performance Guidelines (Table 5-1 in the IWMP-Water Infrastructure) Maximum Day Demand Must meet maximum day demand with the largest well out of service Storage The storage requirements for drinking water shall be a sum of the Equalizing Storage (20% of MDD), Fire Storage (Fire Flow x Duration), and Emergency Storage (10% of MDD). The reservoir size shall meet the demands of the service area, and the maximum reservoir sidewall height shall be 16 feet. Table 3 Potable Water Storage Criteria (Table 5-1 in the IWMP-Water Infrastructure and Table 5 in the Water Guidelines and Standards) Storage requirement Reservoir sidewall height (maximum) 20% of MDD + Fire Flow x Duration + 10% of MDD 16 feet 3.2 Reclaimed Water Reclaimed Water Supply Per previous agreements with the WSLG, the project common open space areas will be irrigated by reclaimed water. Until such time reclaimed water is supplied to the project, the reclaimed water irrigation system will be supplied by either potable water or untreated well water Reclaimed Water Facility System Design The reclaimed water system shall be designed to the same criteria as the potable water system with the exception of the fire flow requirement, the storage factor requirement, and the minimum pressure limitation. Storage requirement Reservoir sidewall height (maximum) Table 4 Reclaimed Water Storage Requirements (Table 5-5 in the IWMP-Water Infrastructure and Table 8 in the Water Guidelines and Standards) 1.0 x ADD 16 feet Desert Trails Master Water System Design Report Page 5

11 4. DEMAND DESIGN CRITERIA 4.1 Service Area Desert Trails is located within the Central Service Area of SPA 3 as designated by the IWMP and WSLG Master Water Study. The Water Campus to serve the Central Service Area is located within the Desert Trails project. Desert Trails shall dedicate the required land to serve the ultimate water campus facilities; however it shall only be responsible for construction of the facilities necessary to serve the Desert Trails project demands. 4.2 Land Use/ Population Projections On-Site Potable Service Area The Desert Trails project consist of approximately 890 acres, planned for a ±1,396 LDR residential units (2 5 du/ac), ± 739 MDR (4-8 du/ac) residential units, ± 15 acre school site (serving approximately 1,200 students), ± 35 acre regional public park, and ±30 acres of MU (mixed use) property. Desert Trails also incorporates ±205 acres of natural desert open space (non-irrigated) and ±160 acres of improved common area open space into the project plan. The Land Use Map and Development Summary for the development can be seen in Figures 2 & Off-Site Potable Service Area Areas of the SPA 3 Central Service Area located outside of the Desert Trails project boundary are considered off-site. Water demands associated with the off-site areas were taken from the approved WSLG Master Water Study. 4.3 Potable Water Demand Criteria City of Surprise IWMP The IWMP update has revised the Potable Water Demand by calculating demand based on actual demands from meters within the community and comparing to surrounding community standards and city guidelines. The proposed demand factors may be viewed below in Table 5. Desert Trails Master Water System Design Report Page 6

12 Table 5 IWMP Potable Water Demand Factors (Table A-4 in the IWMP-Water Resources) Land Use Category Type Demand Units Factor Rural Residential (0-1 du/acre) Residential 320 gpd/du Suburban Residential (1-3 du/acre) Residential 320 gpd/du Low Density Residential (3-5 du/acre) Residential 320 gpd/du Medium Density Residential (5-8 du/acre) Residential 290 gpd/du Medium/High Density Residential (8-15 du/acre) Residential 290 gpd/du High Density Residential (15-21 du/acre) Residential 290 gpd/du Surprise Center Non-Residential 2,000 gpd/acre Commercial Non-Residential 2,000 gpd/acre Mixed Use Gateway Non-Residential 2,200 gpd/acre Open Space Non-Residential 0 gpd/acre Public Facilities Non-Residential 1,000 gpd/acre Proposed Potable System Demand Criteria The Desert Trails development will implement the potable water demand factors as proposed in the IWMP with the exception of school demands. The potable water demand for the proposed Desert Trails school site has been taken from Table 3 of the City of Surprise Water Guidelines & Standards, as the latest IWMP does not specify a potable demand for this type of land use. Max Day Demand (MDD) Peak Hour Demand (PHD) Table 6 Potable Water Peaking Factors (Table 5-1 in the IWMP-Water Infrastructure) 2.0 x Average Day Demand 3.0 x Average Day Demand Single Family Residential Commercial Table 7 Fire Flow Criteria (Table 5-1 in the IWMP-Water Infrastructure) 2,000 gpm for 2 hours 3,000 gpm for 3 hours 4.4 Reclaimed Water Demand Criteria In regards to the water demands required for landscape irrigation, the Desert Trails development will utilize a composite irrigation demand based on the demand factors specified below in Table 8 and taken from the IWMP. Per preliminary landscape estimates, it has been assumed that irrigated open space areas will consist of 25% turf and 75% drip Irrigation resulting in an irrigation demand of 1,975 gpd/acre project wide. The amount of irrigated open space has been projected based on 20% open space per parcel and the typical collector and arterial street cross sections for each street. Desert Trails Master Water System Design Report Page 7

13 Table 8 IWMP Reclaimed Water Demand Factors (Table A-4 in the IWMP-Water Resources) Land Use Category Type Demand Units Factor Turf Landscape 4,000 gpd/acre Xeriscape Landscape 1,300 gpd/acre Desert Landscape 0 gpd/acre Max Day Demand (MDD) Peak Hour Demand (PHD) Table 9 Reclaimed Water Peaking Factors (Table 7 in the Water Guidelines and Standards) 2.0 x Average Day Demand 2.5 x Max Day Demand 5. WATER SYSTEM MODELING 5.1 WSLG and Ultimate Water Distribution System The WSLG Master Water Study identifies the necessary potable and reclaimed water infrastructure for two scenarios. The first scenario addresses the infrastructure necessary to support the WSLG projects, and the second situation addresses the ultimate build out based on the City of Surprise General Plan The Master Water Study divides the SPA 3 into three primary potable water booster pump station service areas based on relative location and elevation and referenced as West, Central, and East. The Desert Trails project is located within the Central Service Area and represents approximately 900 acres of the total 3,200 acres. The WSLG phase for Central Area includes Desert Trails (formerly Fox Trail) and Ana Mandera (formerly Rotolo). The Master Study identifies the location of the Water Storage Facilities and Booster Pump Station to serve the central area to be located at the southwest corner of 211 th Avenue and Pinnacle Peak Road within the Desert Trails project. The study also identifies the required major infrastructure size for the well transmission system, potable water distribution system, reclaimed water transmission system, and reclaimed water distribution system. The Master Water Study exhibits illustrating the WSLG and Ultimate systems may be viewed in Appendix H. It is important to note that the WSLG Master Water Study was prepared utilizing the City of Surprise 2006 design standards Desert Trails Master Water System Design Report Page 8

14 and an update to the WSLG report addressing the reduction in water demand factors may substantially reduce regional water facilities requirements. 5.2 Desert Trails Water Distribution System As discussed above, it is our understanding that the Desert Trails Water Campus will provide the land necessary for the Central Service Area Ultimate Condition storage and pumping requirements. The Water Campus construction shall be phased as to allow for expansion as regional development warrants. The Desert Trails Water Distribution System has been modeled to define the necessary infrastructure required to allow the project to develop as an independent water distribution system Network Analysis The computer program H 2 OMap was used to analyze the proposed water system. The program was developed by MWH Soft, Inc. to perform geospatial hydraulic analysis for pipe networks. The program uses a network of links, nodes, valves, and reservoirs to represent the geometry of the proposed water system and calculate steady-state simulations of flows for pressurized water distribution systems. Table 10 identifies the City of Surprise hydraulic criteria and guidelines that were applied to the water system model. Table 10 City of Surprise Water System Design Criteria (Table 5-1 in the IWMP-Water Infrastructure) Design Component Criteria Minimum Residual Pressure Peak Hour Demand 40 psi Maximum Day Demand Plus Fire Flow 20 psi Maximum System Pressure 100 psi Maximum Velocity 5 ft/s Maximum Fire Flow Velocity 10 ft/s Hazen-Williams Coefficient 130 The Desert Trails Proposed Water Layout, the Ultimate Condition Water Layout, the Desert Trails Reclaimed Water Layout, and Desert Trails Water Transmission Layout can be seen on Plates 1, 2, 3, and 4. The plates illustrate the general locations, sizes, and node labels for the H 2 OMap water model. The water source Desert Trails Master Water System Design Report Page 9

15 that supplies the distribution system is modeled using a fixed reservoir with a hydraulic grade line (HGL) of 1,689 feet, based on the HGL established in the WSLG Master Water Study. The groundwater source and transmission lines have not been modeled as part of this report Modeling Scenarios Desert Trails Potable Water Distribution Model The Desert Trails Potable Water Distribution Model has been established to identify the potable water infrastructure necessary to serve the demands of the Desert Trails project. The four scenarios analyzed for this model represent the extremes in flow potential within the system and include: Average Day Demands, Peak Hour Demands, Maximum Day plus Fire Flow (Residual Pressure), and Maximum Day plus Fire Flow (Velocity). The Average Day Demand scenario provides the situation in which localized flows are at a minimum and pressures are at a maximum. The Peak Hour Demand scenario provides the instance where flows are at a maximum and pressures are at a minimum. The Maximum Day plus Fire Flow (Residual Pressure) scenario places a fire flow demand on each node to ensure that fire flow protection is available and the minimum residual pressure is maintained throughout the system. Lastly, the Maximum Day plus Fire Flow (Velocity) scenario places a fire flow demand during a time period where flows are at a maximum and pressures at a minimum. The node chosen for the fire flow is typically a node that is furthest from the water source or has the greatest positive elevation difference from the water source. This location typically represents the minimum system pressure location Ultimate Condition Potable Water Distribution Model The Ultimate Condition Potable Water Distribution Model inserts the Desert Trails Distribution System into the WSLG Ultimate Potable Water Distribution System to ensure that there are no detrimental effects of the Ultimate Distribution System on the Desert Trails Distribution System and vice versa. In this condition all off-site demands within the Central Service Area of the SPA 3 have been referenced Desert Trails Master Water System Design Report Page 10

16 from the WSLG Master Water Study, which utilizes the 2006 City of Surprise Water Guidelines and Standards demand criteria. However, all on-site demands in the Ultimate Condition Potable Water Distribution Model are consistent with the Desert Trails Potable Water Distribution Model. The Ultimate Condition Potable Water Distribution Model will analyze the same scenarios as the Desert Trails Model Desert Trails Reclaimed Water Distribution Model The Desert Trails Reclaimed Water Distribution Model has been established to identify the reclaimed water infrastructure necessary to serve the project. The two scenarios analyzed for this model represent the extremes in flow potential within the system and include: Average Day Demands and Peak Hour Demands. The Average Day Demand scenario provides the situation in which localized flows that are at a minimum and pressures that are at a maximum. The Peak Hour Demand scenario provides the occasion where flows are at a maximum and pressures are at a minimum Desert Trails Water Transmission Model The Desert Trails Water Transmission Model has been established to identify the preliminary water transmission infrastructure necessary to serve the project. The Desert Trails Transmission System was modeled under one condition where all wells are operating simultaneously at a maximum output of 500 gpm. Fixed reservoirs have been established to represent each well, while constant 15-hp pumps have been utilized at each reservoir for simplicity sake in the model. 500 gpm maximum flow control valves are located downstream of each pump to ensure that each well is supplying exactly 500 gpm to the water supply facility. This method was utilized to establish a conservative estimate of velocities and head losses within the pipes. It is important to note that the Desert Trails Well Transmission System, including transmission line sizes, phasing, and pump parameters, will need to be modeled and designed based on actual well production and testing. Desert Trails Master Water System Design Report Page 11

17 6. PROPOSED CONDITIONS 6.1 Potable Water and Reclaimed Water As discussed previously, the Desert Trials project shall be designed to comply with the City s requirement for a dual water system. The calculations shown herein identify the potable and reclaimed water needs individually with an option for a combined system. For the purposes of this report, a combined system is defined only by sharing the water production facilities, water storage facilities, and booster pump station facilities. It is currently anticipated to implement one of the booster pump alternatives discussed in section Booster Stations and Pressure Zone. The Desert Trails water supply, storage, and booster pump requirements have been analyzed on a per phase basis, so as to determine the water infrastructure required as the project develops. The Desert Trails Phase Map can be seen in Figure 4. If necessary, individual water models on a per phase basis will be submitted concurrent with the preliminary plats for each phase Water Supply The water supply for the Desert Trails project will be provided by groundwater wells. The total required number of wells shall be designed to meet the Maximum Day Demand with the largest well out of service. Exact locations and production capacity of each well to serve the site will be determined based on actual well production and testing. A Hydrogeologic Investigation and Water Supply Strategy report is currently being prepared to identify potential well sites to serve the site. One well currently exists on-site and was drilled, developed and tested in late 2001, early 2002 (DT Well #1, ). DT Well #1 shall be videoed, cleaned, and the production and water quality shall be tested in order to prepare a Well Evaluation Report with rehabilitation recommendations for submittal to the City of Surprise prior to initiating completion of the well. A minimum number of wells was determined using the City maximum production rate of 1,500 gpm and an estimated number of wells was determined using the estimated well capacity of 500 gpm. The total number of wells required to meet the Desert Trails demands is presented below in Tables (detailed calculations are included with the tables in Appendix B). Additionally, per the WSLG Master Water Study, the quality of the wells may also indicate that they Desert Trails Master Water System Design Report Page 12

18 require treatment, which can reduce the usable well capacity by up to 25%. In the event that the actual average usable well production rate for any of the BPS service areas is lower than the estimated 500 gpm, the number of wells required based on the calculated projected capacity may become excessive. Should the number of wells become excessive, the required City standard well capacity may possibly be reduced based on actual achieved population densities and possibly a reduction in the amount of redundancy. However, any reduction in the required well capacity standard shall be made at the discretion of the City of Surprise. The preliminarily located Well Sites to serve the Desert Trails project may be viewed on Plate 1. Table 11 Desert Trails Potable Water Well Calculations Desert Trails Phase Cumulative Minimum Number of Wells Cumulative Estimated Number of Wells Phase 1A, 1B, 1C 2 3 Phase Phase Phase Phase Phase Table 12 Desert Trails Reclaimed Water Well Calculations Desert Trails Phase Cumulative Minimum Number of Wells Cumulative Estimated Number of Wells Phase 1A, 1B, 1C 1 1 Phase Phase Phase Phase Phase Table 13 Desert Trails Combined Water Well Calculations Desert Trails Phase Cumulative Minimum Number of Wells Cumulative Estimated Number of Wells Phase 1A, 1B, 1C 2 3 Phase Phase Phase Phase Phase Desert Trails Master Water System Design Report Page 13

19 6.1.2 Transmission Lines The analysis of the Desert Trails Water Transmission System illustrates the required transmission line sizes to convey the adequate demands from the wells to the Desert Trails water campus. The layout and required line sizes of the transmission layout can be seen on Plate 4. The preliminary phasing of the Desert Trails water transmission infrastructure can be seen in Figure 8. It is important to note that these lines have been sized based on an assumption of 500 gpm being delivered from all 5 wells simultaneously. Final transmission line sizes will be determined based on actual well production and testing Storage Facilities The City design standards require that each BPS service area provide a potable storage capacity equal to a combination of 30% of the Maximum Day Demands plus a volume equal to the fire flow multiplied by the fire flow duration. The provided reclaimed storage must be equal to the Average Day Demand. The results of the calculations on a per phase basis can be seen below in Table 14. In order to obtain the Combined System Storage, the average day demand for the reclaimed water system is added to the potable storage requirement discussed above. Table 14 Desert Trails Storage Requirements Desert Trails Phase Cumulative Potable Water Storage Required Cumulative Reclaimed Water Storage Required Cumulative Combined Water Storage Required (Gal) (Gal) (Gal) Phase 1A, 1B, 1C 799, , ,066 Phase 2 867, ,652 1,094,426 Phase 3 896, ,356 1,144,930 Phase 4 941, ,646 1,211,244 Phase 5 970, ,035 1,259,241 Phase 6 1,014, ,386 1,334,752 Preliminary calculations for the size and number of storage tanks needed to serve the demands of Desert Trails and the Central Service Area at build out have been included in Figure 5.1. Based on these preliminary calculations it is expected that the Desert Trails potable and irrigation demands will be met through a single 1.34 million gallon tank. As future development warrants and reclaimed water becomes available, the water campus will also have the capacity to support million Desert Trails Master Water System Design Report Page 14

20 gallon potable water storage tanks and million gallon reclaimed water storage tank. A preliminary water campus layout depicting this configuration can be seen in Figure 5.2. As has been mentioned previously in the report, the WSLG Master Water Study was prepared utilizing the City of Surprise 2006 demand design standards, and the Desert Trails Distribution System has been analyzed using the demand criteria outlined in the IWMP. Therefore the total amount of required storage for the Central Service Area under the Desert Trails System does not conform to the volumes computed in the WSLG Master Water Study Distribution Lines The analysis of the Desert Trails Potable Distribution System illustrates the required potable water main sizes to supply the adequate demands and maintain acceptable pressures throughout the system during extreme flow conditions. As a function of the proposed land plan and the natural washes that bisect the property, the Desert Trails demands will be met through a major external water loop created by the major water lines in the arterial roads that border and bisect the development, as seen on Plate inch water lines will be utilized within 219 th Avenue and Pinnacle Peak Road, while 16-inch water lines will serve the development through 211 th Avenue and Deer Valley Road. It is noted that the 219 th Avenue and Pinnacle Peak Road water lines within the Desert Trails Proposed (Interim) Layout do not match the lines sizes represented in Figure ES-2 of the IWMP, Near Term ( ) Drinking Water Infrastructure Improvements. However through coordination with the City, it was determined that an additional 4,800 single-family dwelling units could be served with the Desert Trails proposed line sizing thus sufficiently meeting the IWMP near term goals. The water lines in 219 th Avenue and Pinnacle Peak Road will serve the near term demands of the area until such time that growth in the region warrants the construction of 42-inch water lines per the IWMP Figure ES-3: Long Term (2021-Build-out) Drinking Water Infrastructure Improvements. The 16- inch water lines in 211 th Avenue and Deer Valley Road shall be sufficient for serving the long term demands of the region per Figure ES-3. An additional 8 water line loop, P-DT-96, has also been provided to the residential parcels south of Deer Desert Trails Master Water System Design Report Page 15

21 Valley Road via the 8 water line that crosses the Trilby Wash. The water lines that cross the Trilby Wash outside of City Right-of-Way will be located within a dedicated utility easement that will allow for the required access and maintenance of the facilities. In addition to this, the scour depth will be computed at the time of final improvement plan preparation. The water line will be designed with adequate protection should it be determined that there is not adequate cover to protect from scour damage. The waterlines within the model have been provided with multiple points of connection to the overall distribution system and conform to the City of Surprise s requirement for a looped water system. At such time that the development of offsite areas warrant the Ultimate Condition System, the WSLG Ultimate Potable Water Distribution System will tie into the Desert Trails Distribution System with no negative impacts to either system. The Ultimate Distribution System can be seen on Plate 2. The waterline locations in the arterial roadways under the Ultimate Condition System can be seen in Figures 6.1 & 6.2. The proposed Desert Trails potable water infrastructure shall be constructed in phases as the project develops. The preliminary phasing of the Desert Trails potable water infrastructure can be seen in Figure 7. The analysis of the Desert Trails Reclaimed Distribution System identifies the necessary reclaimed water main sizes to supply the required demands and maintain acceptable pressures throughout the system during the peak hour condition. The Desert Trails demands will be served by a major internal water loop created from the reclaimed water lines in Deer Valley Road, the major collector street, and the local streets. The major internal loop will consist of 8 reclaimed water lines and will be fed from the water campus by a 12 reclaimed water line, as seen on Plate 3. At the time of the Ultimate Condition System, the Desert Trails Distribution System will tie into the WSLG Reclaimed Water Distribution Master Plan to provide the necessary redundancy within the SPA 3 Reclaimed Distribution System and meet the off-site demands. Desert Trails Master Water System Design Report Page 16

22 6.1.5 Booster Stations and Pressure Zone Per the WSLG Master Water Study, the Desert Trails project is within BPS pressure Zones 6 and 7. The pressure zone boundaries and HGLs may be viewed in Table 15 below: Table 15 Pressure Zone Boundaries and HGLs Pressure Zone Upper Pressure Zone Boundary HGL 5 1, ,470 1, ,550 1, ,630 1,750 The Desert Trails potable water system will be served by one BPS. The Booster Pump Station pumping capacity was determined as the higher of Peak Hour or Maximum Day plus Fire Flow conditions with the largest pump out of service. The Booster Pump Station Requirement for each phase of the Desert Trails project was controlled by the Maximum Day plus Fire Flow condition. A summary of the cumulative pumping requirements on a per phase basis are shown in Table 16 and detailed calculations may be seen in Booster Pump Station Requirements Table in Appendix B. It is assumed at this time that the Desert Trails potable and reclaimed water demands will be met through one of the following methods: o A single storage tank and single booster pump station that will serve both the potable and reclaimed water demands with potable water through the use of multiple cross connects and back flow prevention devices throughout the development that will allow the reclaimed water lines to be charged from the potable distribution system but will prevent the crosscontamination of potable water from the reclaimed water lines. o An entirely separate distribution system, whereby potable and reclaimed water is stored separately in individual storage tanks and demands are met through the use of separate potable and reclaimed booster pump stations. Although separate tanks and booster pumps shall be used, potable or raw water could be used until reclaimed water is available. Desert Trails Master Water System Design Report Page 17

23 o A single storage tank for both potable and reclaimed water that will feed separate potable and reclaimed booster pump stations. At the time that reclaimed water is available from the City, a separate reclaimed water tank could supply the necessary demands to the reclaimed booster pump. It is important to note that this report is intended to determine the booster pump requirements to serve the Desert Trails development and that the actual number and size of the booster pumps to serve the project will be determined through the subsequent phases of design. Table 16 Potable Booster Pump Station Requirements PHASE Cumulative Pumping Requirement (gpm) Phase 1A 3,226 Phase 1B 3,424 Phase 1C 3,601 Phase 2 3,759 Phase 3 3,825 Phase 4 3,930 Phase 5 3,996 Phase 6 4,098 Table 17 Reclaimed Water Booster Pump Station Requirements PHASE Cumulative Pumping Requirement (gpm) Phase 1A 148 Phase 1B 192 Phase 1C 256 Phase Phase Phase Phase Phase Desert Trails Master Water System Design Report Page 18

24 Table 18 Combined System Booster Pump Station Requirements PHASE Cumulative Pumping Requirement (gpm) Phase 1A 3,374 Phase 1B 3,640 Phase 1C 3,857 Phase 2 4,074 Phase 3 4,170 Phase 4 4,304 Phase 5 4,397 Phase 6 4, SYSTEM MODEL & RESULTS 7.1 Potable Water Distribution System The Desert Trails Proposed Water Layout and the Ultimate Condition Water Layout have been analyzed under four separate scenarios: Average Day Demands, Peak Hour Demands, Maximum Day plus Fire Flow (residual pressure), and Maximum Day plus Fire Flow (velocity). Based on the output data provided from each fixed-rate model, each separate scenario meets the City of Surprise guidelines pertaining to system pressures, pipe velocities and head losses, required demands, and fire flows. The minimum and maximum pressure nodes and maximum pipe velocity and head loss location for each scenario can be seen in Table 19 and Table 20. Detailed node, pipe, reservoir, and pressure valve output data for each scenario can be found in Appendices C and D. Within the detailed output data, it should be noted that several cells within Adjusted Fire-Flow column of the Maximum Day plus Fire Flow (residual pressure) scenario do not contain output data associated with the calculated discharge. The Adjusted Fire- Flow is the hydrant flow required to reduce the Critical Node 1 to the Minimum Design Pressure (20 psi). Analysis of these results reveals that the majority of the undefined nodes is within the upper limit of the psi pressure range and has no assigned Average Day Demand. Due to the fact that pressures within the system tend to range between psi under Average Day Demand conditions, the water source has an infinite supply, and H 2 OMap software has a maximum number of iterations (200), the Desert Trails Master Water System Design Report Page 19

25 model is unable to compute the infinitely large water demands needed to reach the minimum residual pressure of 20 psi at the Critical Node 1. Therefore, there is no issue of concern with these nodes and the distribution systems conform to the City of Surprise criteria during the Maximum Day plus Fire Flow (residual pressure) scenario. Critical Constraint Table 19 Desert Trails Potable Distribution System Model Results Average Day Peak Hour Maximum Day + Fire Flow (Residual Pressure) Maximum Day + Fire Flow (Velocity) Minimum Pressure (psi) Maximum Pressure (psi) Minimum Residual Pressure (psi) Maximum Velocity (ft/s) Maximum Head Loss (ft/ 1,000 ft) Value Location Value Location Value Location Value Location J-DT J-DT-67 N/A N/A J-DT J-DT J-DT-73 N/A N/A J-DT-64 N/A N/A N/A N/A J-DT-67 N/A N/A 0.60 P-R-C 1.79 P-R-C N/A N/A 6.78 P-DT P-DT P-DT-25 N/A N/A P-DT-42 Table 20 Ultimate Condition Potable Distribution System Model Results Critical Constraint (within Desert Trails System) Minimum Pressure (psi) Maximum Pressure (psi) Minimum Residual Pressure (psi) Maximum Velocity (ft/s) Maximum Head Loss (ft/ 1,000 ft) Average Day Peak Hour Maximum Day + Fire Flow (Residual Pressure) Maximum Day + Fire Flow (Velocity) Value Location Value Location Value Location Value Location J-DT J-DT-3 N/A N/A J-DT J-DT J-DT-19 N/A N/A J-DT-19 N/A N/A N/A N/A J-DT-15 N/A N/A 1.50 P-R-C 4.49 P-R-C N/A N/A 5.07 P-R P-R-C 4.24 P-R-C N/A N/A 8.49 P-DT Well Delivery System The Well Delivery System has been modeled under the assumption that 5 on-site wells will operate at a maximum production of 500 gpm. It is imperative to make note that final transmission line sizes will be determined based on actual well production and Desert Trails Master Water System Design Report Page 20

26 testing. Detailed node and pipe output data for the scenario can be found in Appendix F. It is important to note that all pipes within the system maintain velocities below the standard 5 ft/s; however, three pipe segments exceed the standard acceptable head loss of 2 ft/1,000 ft. These pipe segments and their associated head loss are specifically noted below in Table 21. Per conversations with James Shano, Public Works Utilities CIP, Division Manager, and his staff, a waiver will be granted of this specific criterion within the Desert Trails Water Master Plan final approval letter. Table 21 Desert Trails Transmission Pipe Model Results Pipe ID Diameter (in) Flow (gpm) Velocity (ft/s) HL/1,000 ft (ft/1,000 ft) P-DT , P-DT , P-DT , Reclaimed Water Transmission System The reclaimed water transmission lines for the region have been sized as part of the WSLG Master Water Study. At such time that reclaimed water is available, it will be delivered to the Desert Trails Water Campus via the reclaimed transmission line in Deer Valley Road. 7.4 Reclaimed Water Distribution System The proposed Desert Trails Reclaimed Water Distribution models have been analyzed under two separate scenarios: Average Day Demands and Peak Hour Demands. Based on the output information provided from each fixed- rate model, each separate scenario meets the City of Surprise guidelines pertaining to system pressures, pipe velocities and head losses and required demands. The minimum and maximum pressure nodes and maximum pipe velocity and head loss location for each scenario can be seen in Table 22. Detailed node and pipe output data for each scenario can be found in Appendix E. Desert Trails Master Water System Design Report Page 21

27 Table 22 Desert Trails Reclaimed Distribution System Model Results Critical Constraint Average Day Peak Hour Value Location Value Location Minimum Pressure J-DT J-DT-4 Maximum Pressure J-DT J-DT-54 Maximum Velocity (ft/s) Maximum Head Loss (ft/ 1,000 ft) 0.63 P-DT P-DT P-DT P-DT CONCLUSIONS In summary, this Master Water System Design Report has defined the potable and reclaimed water demands associated with the proposed Desert Trails Planned Area Development Zoning Case and modeled these demands to ensure that all proposed infrastructure has been adequately sized, so that the Desert Trails development may operate as an independent water distribution system. Based on the analysis on the proposed water infrastructure, the following conclusions can be made: The water distribution system has been designed in accordance with the criteria established within the City of Surprise Integrated Water Master Plan Water Infrastructure dated July Potable and reclaimed water demands have assigned based on the City of Surprise Integrated Water Master Plan Water Resources dated November, The potable water distribution system has been modeled under two separate scenarios: the Desert Trails Water Layout and the Ultimate Condition Water Layout. The Desert Trails Layout will operate as an independent water distribution system, serving the on-site demands of the Desert Trails development. The purpose of the Ultimate Condition Model is to ensure there are no negative impacts to the Desert Trails system or the WLSG SPA 3 system once build-out has occurred. Desert Trails Master Water System Design Report Page 22

28 The proposed water distribution system will operate within the City of Surprise s Pressure Zone 7. Individual PRVs will also be installed at each service connection to regulate pressures to under the maximum 100 psi requirement. Water demands will be met through the use of on-site wells. The final number and exact locations will be dependent upon the production capacity of each well, as determined based on actual well production and testing. Raw water will be pumped from the on-site wells through raw water transmission lines to the proposed on-site water campus at the southwest corner of 211 th Avenue and Pinnacle Peak Road. The water campus will serve the water treatment needs, together with the storage and booster pump needs of the proposed development based on the City of Surprise criteria. The water distribution results during the Average Day Demand Scenario, Peak Hour Demand Scenario, Maximum Day plus Fire Flow (Residual Pressure), and Maximum Day plus Fire Flow (Velocity) for the Desert Trails Model, Ultimate Condition Model, and Reclaimed Model are in accordance with the design guidelines established by the City of Surprise. Per the most current version of the Development Agreement, Section 4.4.3, potable water storage shall be provided to meet both the potable and nonpotable water storage needs. Non-potable water storage, non-potable water booster pumps or other supplemental equipment associated with the distribution of non-potable water are assumed to be provided by other Central Area developers. Therefore, initially, a single storage tank and single booster pump station will serve both the potable and reclaimed distribution systems with potable water. The other two distribution options listed on page 18 are also still possible options for serving the Desert Trails potable and non-potable water demands. Desert Trails Master Water System Design Report Page 23

29 Per the most current version of the Development Agreement, Section , the non-potable transmission line shall be built in Deer Valley Road between 211 th Ave. and 219 th Ave. The non-potable transmission line between the SPA 3 WRF and 219 th Ave. may be built by the Desert Trails developer if the direct reuse option is selected by the City and the Desert Trails developer. In order to complete the non-potable transmission line to the water campus, the line in 211 th Ave. from Deer Valley Road to Pinnacle Peak Road and to the water campus will need to be completed by other Central Area developers. Until that non-potable transmission line is completed to the water campus, the Desert Trails reclaimed water system will be charged either with potable water or reclaimed water directly from the SPA 3 WRF. Desert Trails Master Water System Design Report Page 24