Full Text
City of Fernley Department of Public Works DESIGN STANDARDS 4.0 - POTABLE WATER SYSTEM DISTRIBUTION AND TRANSMISSION FACILITIES 4.1. DESIGN CRITERIA The following design criteria shall govern the design of water distribution and transmission facilities that are to be dedicated to the City. The intent of these criteria is to promote water system designs that will provide safe, adequate, and dependable potable water service without excessive maintenance costs. The requirements set forth in NAC 445A, NRS 445A and these guidelines, regarding water distribution systems shall be used as design and review guidelines. Improvement plans for water systems and facilities must be reviewed and approved by Public Works. 4.1.1.WATER SUPPLY PRESSURE Distribution system pressure shall meet the requirements of NAC 445A.6711. Public Works will provide the maximum-day pressure at a desired delivery location for design purposes. Under maximum-day demand conditions, normal operating pressures of not less than 40 psi no more than 100 psi shall be maintained at the meter inlet for all service connections. Peak-hour pressures shall be maintained between 30 psi and 100 psi. Maximum-day pressures during a fire event shall be maintained between 20 psi and 100 psi. Pressure reducing stations are not allowed unless otherwise noted. Private individual pressure reducing valves shall be installed and maintained by the owner, on private property, in accordance with the most current adopted edition of the International Plumbing Code (IPC). Use of booster pumping stations to increase pressures in localized areas may be permitted on a case-by-case basis. Private individual booster pumping stations may be installed and maintained by the owner, on private property, in accordance with the IPC. Calculations of onsite system operating pressures, by the engineer should include any required backflow prevention devices, in accordance with Public Works Detail Sheets. Copies of the backflow prevention program and rules and regulations are available from Public Works. 4.1.2.WATER DEMAND RATES Demand values of 1000 gallons per day (gpd) per residence, which is equivalent to one Equivalent Residential Connection/Unit (ERC/U) for a metered system, shall be utilized when determining total number of will-serves for a specific development. A peaking factor of 2.0 shall be used to determine the peak hour demand. 4.1.3.REQUIRED FIRE FLOWS Fire flows shall be as required by the Fire District. Minimum residential fire flow has been determined by the Fire District to be 1000 gpm for 2 hours. A residual pressure of 20 psi shall be maintained at any point in the system during a fire flow event. Calculations to determine the residual pressure and available fire flows shall assume the maximum day demand is occurring in the system. All fire flow demands shall be met from storage and not groundwater pumping stations. 4.1.4.MAXIMUM VELOCITIES Sizing of distribution and transmission mains shall be such that water velocity during all conditions of flow, other than fire flow, does not exceed 6.5 feet per second (fps). Under fire flow conditions with maximum day water demand the water velocity shall not exceed 10 fps. PW-1 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS 4.1.5.WATER SYSTEM MODEL REPORT Public Works is required by NAC 445A to report to the Bureau of Health Protection Services regarding the System’s delivery capabilities to the new developments. Public Works will model all distribution and transmission lines, pumping facilities and storage tanks to evaluate the performance of the proposed facilities and their impact on existing facilities. If the Engineer-of-Record requests that a model of the particular development be constructed to assist in the design of the distribution system prior to developing improvement plans, a preliminary model may be developed. The Engineer-of-Record must submit to Public Works a base map which includes proposed topography, street and lot configuration, and piping layout including a model fee determined by the “Application for a City of Fernley Water Model”. Public Works will include the proposed facilities in the City’s water model and provide feedback on required water line sizes, pumping facility capacities, storage tank sizes, locations and other related items. 4.2. TRANSMISSION MAINS Dedicated transmission mains are mains used solely for filling water tanks. It is preferred to design transmission mains that tie into distribution systems en-route to a water tank. In addition to limiting maximum velocities, when pumping is involved, the transmission main shall be the most economical size considering costs and the present worth of the incremental pumping costs associated with the pipe diameter under evaluation. This analysis shall be for a twenty (20) year period with an interest rate of ten (10) percent. Transmission main pipe shall be either cement- mortar-lined DI or PVC. PVC pipe shall be in conformance with AWWA C900 for diameters between 4 and 12 inches, and C905 for diameters larger than 12 inches. All ductile iron pipe and fittings shall be cement-mortar lined in accordance with AWWA C104. The exposed (non- buried) exteriors of DI shall be epoxy coated to 10 mils (minimum) of Federal Safety Blue and the buried exterior of DI shall be wrapped with 8 mil polyethylene film and sealed in accordance with AWWA C105. The transmission main shall be pressure rated for the maximum working pressure including surge pressures resulting from an instantaneous valve closure. A transient surge analysis is required for all pump station designs. 4.2.1 PIPELINE OVERSIZING Pipeline oversizing may be required by Public Works to account for future growth. Oversizing will be determined by Public Works based on water modeling analysis. The pipeline size required for the development will be determined by the analysis as well as the pipeline oversizing. Oversizing agreements will be as defined in Chapter 17 of the Community Development Code. 4.3. DISTRIBUTION SYSTEM PIPING Distribution mains shall be sized to deliver required flows at the pressures specified in Section 4.1.1. The minimum size for distribution piping shall be eight inches. All mains shall be adequately looped and networked to provide alternate flow routes. Distribution piping shall be DI in accordance with AWWA C150 and C151 or PVC in accordance with AWWA C900 or C905. The distribution main shall be pressure rated for the maximum working pressure and must include surge allowances. The pipe shall be designed for the internal and external loads placed on it. Minimum pipe rating shall be Pressure Class 150 for DI, Class 150 for C900 PVC and Class 160 for C905 PVC (Public Works may require higher classes for special circumstances). Seismic design shall be incorporated in all areas where the transmission main crosses a fault. Fault mapping shall be submitted if applicable. PW-2 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS A Public Works representative must be present during a tie-in (TI) from any new water system (new development, upgrades, etc.) to the City’s existing water distribution system. 4.3.1. MAIN LOCATION All water mains shall be installed in public rights-of-way or public easements. Minimum easement width shall be 10 feet. Per NAC 445A, unless approved by the Bureau of Health Protection Services, water mains shall not be installed in public utility easements on private property. Minimum cover over a water main shall be three and one half (3.5) feet. Location of water mains in public right of way shall conform to the Pubic Works Standard Details. Unless waived by Public Works, all extension mains shall run along the entire frontage of the developer’s lot or parcel. Public Works may require that mains extend to the edge of the property deemed appropriate by Public Works for future development. Mains must be aligned in such a way that minimizes other Public Works conflicts. Minimum separations and clearances should be maintained whenever possible. If minimum separations cannot be maintained, alternatives permitted by the Bureau of Health Protection Services are indicated on the Public Works Standard Detail Sheets. 4.3.2. STREAM AND DITCH CROSSINGS Crossing details and profiles of pipe, piers, anchorage, transition couplings, etc. shall be shown on the improvement drawings. Ductile iron pipe with bolted flange fittings or restrained joint piping shall be used under the full stream or ditch width, and ten (10) feet on each side. All stream and ditch crossings shall have a minimum clearance of 5 feet between the stream bottom and top of pipe, and shall be enclosed in a pipe sleeve. Consideration shall also be given to protecting the pipe during stream flooding and scour. A scour analysis shall be provided as required by Public Works. Stream crossing and construction methods shall be approved by the appropriate agency (Nevada Division of Environmental Protection, Nevada Department of Fish and Game, Nevada State Lands, Nevada Bureau of Health Protection Services, and the Corps of Engineers - see NAC 445A). 4.3.3. TRANSMISSION AND DISTRIBUTION VALVES Valves shall be installed at minimum intervals of 1,000 feet on transmission mains and 500 feet on distribution mains. The valves shall be located so that any section of main can be shut down without going to more than three locations to close valves. As a minimum, there shall be at least two valves at every tee fitting and three valves at every cross fitting on pipe ten (10) inch in diameter and smaller. For pipe larger than 10-inches there shall be three valves at every tee fitting and four valves at every cross fitting. Valves 12-inch and smaller shall be resilient-seated gate valves installed with ASTM B-132 bronze valve stems and shall be designed such that if excessive input torque is applied, stem failure shall occur above the stuffing box. The stem material must provide a minimum 70,000psi tensile strength. Two-piece stem collar valves are not acceptable. Valves larger than 12-inch shall be butterfly valves, with the valve seat located on the valve body. The butterfly valves shall also have shaft seals to be designed to allow replacement without removing the valve shaft. Valves shall be in conformance with AWWA C509 and C504. Valves shall be provided with a shop-applied fusion bonded epoxy coating 10 mils thick on interior and exterior surfaces. All unburied valves shall be over-coated with 3 mils of Federal Safety Blue epoxy. Valve shafts shall be solid 18-8 Type 304 stainless steel. Valves shall include valve boxes that are set at the same elevation as the existing grade, either in a traveled way or untravelled way. Valve boxes shall incorporate concrete collars in all installations per the Public Works Standard Details. PW-3 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS All distribution control-valving shall be designed for installation in Public Works-approved below-ground vaults or above-ground enclosures. Valve applications shall be approved by Public Works and in accordance with manufacturer's recommendations. Valves shall be Mueller valves unless otherwise met by criteria stated above and approved by Public Works. 4.3.4. FIRE HYDRANTS In all areas where fire hydrants are required along roadways, the spacing between adjacent hydrants shall be determined by but shall not exceed 500 feet in residential areas and 300 feet in institutional, commercial, and industrial areas. Hydrant spacing shall be measured along the shortest route within the traveled way of streets that connect the hydrants. Wherever possible, hydrants shall be located at street intersections. Fire hydrants shall not be located in cul-de-sacs unless specified by the hydrants shall be located a minimum of 12-inches behind back-of-sidewalk. All other hydrants along roadways shall be located at the intersection of property lines with the street right-of-way boundaries. No parcel shall be more than 250 feet away from a fire hydrant. The appropriate fire prevention district shall determine the spacing between adjacent fire hydrants in areas and locations other than along roadways. All hydrants shall be freeze-proof dry barrel hydrants and shall comply with the Public Works Standard Details. The hydrant lateral, which interconnects the distribution main and the hydrant, shall be not less than six inches in size. A 6-inch gate valve shall be installed in all hydrant laterals. The shut-off valve shall be located on the water main with a flanged tee. All hydrants shall be installed with a Harrington, 5-inch, Storz fittings with cap and cable (Harrington Part No. HPHA50-45NH) and shall be enameled with Sherwin-Williams B54R38 paint per Public Works Detail Sheets. Hydrants that are permanently inoperable shall be painted black including nozzle caps, tops, barrels, and all visible parts. Hydrants that are temporarily out-of-service shall be wrapped and valved off-line. 4.3.5.POTABLE WATER SERVICES All services shall be metered. Whenever possible, double meter boxes shall be located on property lines between lots with a single service line from the main to the meter box. In other situations, the meter box location shall be within the public right-of-way or easement adjacent to an existing or proposed curb line. In alleys or easements, meter boxes shall be located at a point as close as practicable to the property line near the water main location. Meter boxes shall be installed at a maximum of 4 feet behind back of walk or at distances from back of walk as identified on the Public Works Standard Details. Under no circumstance shall meter boxes be located inside fenced yards or within driveways, driving surfaces, and other areas where access for operation and maintenance may be restricted. There shall be no obstructions within three feet of meter boxes. Minimum service line size is ¾-inch for service to a single meter and 1-inch to double meters. Water meters shall be Sensus SR2 TRPL (Touch Read), or approved equal, remote- read meters with remote read disks located in the meter box lid. The meters, meter boxes, meter setters, curb stops, service lines, and radio-read module MXU units shall be installed in accordance with Public Works Standard Detail Sheets. MXU units must not be placed PW-4 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS within 3 feet of a power source. Commercial and industrial services shall be designed by a registered engineer and submitted for Public Works review prior to approval. Services shall also incorporate a “customer valve” located on the customer side of the meter box and shall be as defined on the Public Works Standard Details. A valve riser and cap shall be provided for the customer valve. Water services in subdivisions will be marked at the curb with an approved permanent method. 4.3.6. FLUSH VALVE ASSEMBLIES A temporary flush valve assembly (FVA) will be permitted at a “dead-end” main (or cul-de- sac) on a case-by-case basis. A permanent FVA will not be permitted. A fire hydrant will serve as FVA or to purge air if located at the end of a water line where there is a planned future extension. FVA calculations (using a minimum velocity of 2 fps in the main during flushing and 15 fps in the FVA) must be provided for pipe sizes greater than 12 inches. Temporary FVA’s shall be installed in accordance with the Public Works Standard Detail Sheets. 4.3.7. AIR AND VACUUM VALVES AND AIR-RELEASE VALVES Air and vacuum valves and air-release valves shall be installed at all high points in the water mains, water pumping stations, and where required by Public Works. Air and vacuum valves and air-release valves shall be tested and approved in accordance with AWWA C512 Standard for Air-Release, Air/Vacuum, and Combination Air valves for Water Works Service. 4.3.8. PRESSURE REDUCING VALVES Pressure reducing valves (PRV) may be provided on distribution mains as necessary so that the system pressure will not exceed 80 psi static pressure at the lowest ground elevation of a pressure zone. Pressure reducing valves shall be installed in concrete vaults. Concrete vaults shall be rated for H-20 traffic and shall be equipped with a spring assisted weatherproof double hatch cover. The installation shall include bypass piping and a secondary PRV including isolation valves to allow removal of either of the pressure reducing valves. Pressure reducing valve stations must be designed by an engineer and all calculations must be submitted to Public Works for review and approval. Differential pressure across the valve must not exceed manufacturer’s recommendations to preclude cavitation. Pressure reducing stations must be designed for locations that minimize the number of stations involved with the maximum amount of benefit to services. Pressure reducing stations may be incorporated in booster pumping station design. 4.3.9. CROSS-CONNECTION The term “cross-connection” shall mean any unprotected actual or potential connection, auxiliary intake, bypass, or other piping arrangement between a public water supply and any other source through which it is possible to introduce industrial fluid, gas, or other substance from a source which does not comply with the Primary or Secondary Drinking Water Standards by back-siphonage and/or backpressure and used water. Unprotected cross- connections with the public water supply are prohibited. Per the Public Works Standard Details, an approved backflow prevention assembly shall be installed on each service line to a customer’s water system at or near the property line or immediately inside the building being served; but in all cases, before the first branch line leading off the service line wherever the following conditions exist: PW-5 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS 1. In the case of premises having an auxiliary water supply which may not be of safe bacteriological or chemical quality and which is not acceptable as an additional source by Public Works, the auxiliary water system shall not be directly (physically) connected to the municipal water system. 2. In the case of premises on which industrial fluids or other objectionable substances are handled in such a fashion as to create an actual or potential hazard to the public water system, the public system shall be protected against backflow from the premises by installing an approved backflow prevention assembly in the service line appropriate to the degree of hazard. 3. In the case of premises having internal cross-connection that cannot be permanently corrected or controlled, or intricate plumbing and piping arrangements or where entry to all portions of the premises is not readily accessible for inspection purposes, making it impracticable or impossible to ascertain whether or not dangerous cross-connections exist, the public water system shall be protected against backflow from the premises by installing an approved backflow prevention assembly in the service line. 4.3.10. BACKFLOW PREVENTION DEVICES 4.3.10.1. VACUUM BREAKERS An atmospheric vacuum breaker or pressure vacuum breaker shall be used only for protection against pollution or contamination under conditions of backsiphonage. Vacuum breakers (AVB, PVB or SVB) may be used for irrigation systems, including systems for irrigation of median strips. 4.3.10.1.1. ATMOSPHERIC VACUUM BREAKER (AVB) An atmospheric vacuum breaker is an assembly that contains an air inlet valve, a check seat, and an air inlet port(s). The following must be met for AVB installations: 1. The vacuum breaker must be installed not less than 6 vertical inches above the highest point of piping. 2. Any associated shutoff valve must be located upstream from the vacuum breaker. 3. The vacuum breaker must not be subjected to operating pressure for more than 12 hours in any 24-hour period. 4.3.10.1.2. PRESSURE VACUUM BREAKER (PVB) A pressure vacuum breaker is an assembly that contains an independently operating internally loaded check valve and an independently operation loaded air inlet valve located on the discharge side of the check valve. The following conditions must be met for PVB installations: 1. The PVB must be installed upstream from the terminal shutoff valve. 2. The PVB must be installed not less that 12 vertical inches above the highest point of the outlet, valve or piping. 4.3.10.1.3. SPILL RESISTANT PRESSURE VACUUM BREAKER (SVB) A spill resistant pressure vacuum breaker is an assembly that contains an independently operation loaded air inlet valve located on the discharge side of the check valve. The following conditions must be met for SVB installations: 1. The SVB shall be installed upstream from the terminal shutoff valve. PW-6 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS 2. The SVB must be installed not less than 12 vertical inches above the highest point of the outlet, valve or piping. 3. The SVB must not be installed at a location where backpressure will occur. 4.3.10.2. DOUBLE CHECK VALVE ASSEMBLY A double check valve assembly means an assembly that: 1. Is composed of two independently acting, approved check valves; 2. Has closing, resilient seated shutoff valves attached at each end; 3. Is fitted with properly located, resilient seated test cocks; and 4. Has been tested and approved in accordance with American Water Works Association Standard C511, by an approved backflow testing laboratory. Double check valve assemblies are required in the following: 1. A building that has multiple stories and booster pumps or elevated tanks to distribute potable water. 2. A building that exceeds 40 Feet in height, as measured from the service connection to the highest water outlet. 3. Class 1, Class 2, or Class 3 fire sprinkler system. 4. Irrigation system, including a system for irrigating median strips. 4.3.10.3. REDUCED PRESSURE PRINCIPLE ASSEMBLY A reduced pressure principle assemble means an assembly that 1. Contains: a) two independently acting approved check valves; and b) a hydraulically operating, mechanically independent pressure differential relief valve located between the approved check valves and below the upstream check valve; 2. Has properly located, resilient seated test cocks and closing, resilient, seated shutoff valves at each end of the assembly; 3. Is designed to protect against pollution and contamination under conditions of back-siphonage or backpressure; and 4. Has been tested and approved by a back flow testing laboratory. Reduced pressure principle assemblies are required in the following: 1. Irrigation system, including a system for irrigating median strips, if facilities have been installed for pumping, injecting or applying fertilizers, pesticides or other hazardous systems. 2. Hotel/Motel 3. Casino 4. Condominium/Townhouse/Apartments 5. Any commercial building where a specific business activity has not been identified 6. A building in which one or more sewage pumps or sewage ejectors have been installed 7. Class 4, class 5, or class 6 fire sprinkler system 8. Hydronic heating system that contains any chemical additives PW-7 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS 9. Baptismal font of a church 10. Beverage bottling facility 11. Brewery 12. Cannery 13. Food processing facility 14. Packing house or rendering facility 15. Cold storage facility 16. Dairy processing facility 17. Restaurant or other facility in which food is served 18. Dental Clinic 19. Hospital, medical building, or clinic 20. Convalescent or nursing home 21. Sanitarium 22. Morgue, mortuary, or facility conducting autopsies 23. Laboratory, including laboratories of teaching institutions or another biological or analytical facility 24. School, college, or university 25. Motion picture production facility 26. Newspaper printing or publishing facility 27. Veterinary clinic, pet shop, or pet grooming facility 28. Laundry or dry cleaning facility 29. Dyeing facility 30. Mechanical, chemical, or electrochemical plating facility 31. Pool or spa 32. Mobile home or RV park 33. Fishery, fish hatchery, dock, marina, or any facility located on a waterfront 34. Power production facility 35. Oil or gas production, storage, or transmission 36. Radioactive material storage, handling, or processing facility 37. Sand or gravel processing 38. Any facility in which water is used to manufacture, store, compound, or process chemicals for industrial purposes; chemicals are added to water used in the compounding or processing of products; chemicals are added to the supply of water; or the supply of water is used for the transmission or distribution of chemicals 39. Aircraft or missile manufacturing facility 40. Motor manufacture, repair, or cleaning facility 41. Film processing or manufacturing facility 42. Ice manufacturing facility 43. Metal cleaning, manufacturing, or processing facility 44. Natural or rubber manufacturing facility 45. Paper or paper products manufacturing facility 46. Any other facility for manufacturing, processing, or fabricating PW-8 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS 4.3.10.4. AIR GAP An air gap is a physical separation between a point of free-flowing discharge from a pipe that supplies liquid to an open or non-pressurized vessel and the overflow rim of that vessel which is: 1. At least twice the effective diameter of that pipe or, if the pipe is affected by side walls, at least three times the effective diameter of that pipe; and 2. In no case less that one inch Air gaps are required for the following: 1. Any portable spraying or cleaning equipment. 2. Sewage collection, storm drainage, or distribution of reclaimed wastewater. Conditions not listed above, or that require special consideration, shall be evaluated on a case by case basis and the appropriate backflow protection device shall be determined by the City. 4.3.10.5. ASSEMBLY REQUIREMENTS Backflow prevention assemblies required herein shall be a make, model and size approved by the Public Works and as shown on the Public Works Standard Details. An approved backflow prevention assembly shall mean an assembly that has been manufactured in full conformance with AWWA C510 Standard for Double Check Valve Backflow-Prevention Assembly, and AWWA C511 Standard for Reduced-Pressure Principle Backflow-Prevention Assembly, and have met completely the laboratory and field performance specifications of the Foundation for Cross-Connection Control and Hydraulic Research of the University of Southern California (USC as established in: “Specifications of Backflow Prevention Assemblies-Section 10 of the most current edition of the Manual of Cross-Connection Control.” 4.3.10.6. TESTING REQUIREMENTS It shall be the responsibility of the customer at the premise where backflow prevention assemblies are installed to have certified inspectors and operational tests made at the customer’s sole expense at least once per year. Test results shall be submitted to the Public Works within five days of completion. In those instances where the Public Works deems the hazard to be great enough, certified inspections may be required at more frequent intervals. These inspections and tests shall be performed by a tester certified by the American Water Works Association, California-Nevada Section. The customer shall notify the Public Works two working days in advance when the tests are to be undertaken so that a Public Works representative may witness the tests. All backflow prevention devices shall be tested: 1. Upon installation 2. At least annually 3. Upon relocation or repair The City may require a more frequent testing schedule if it is determined to be necessary. PW-9 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS A test report in a form acceptable to Public Works shall be filed with Public Works each time a backflow prevention device is installed, repaired, relocated, or replaced. Approval from the City must be obtained before a backflow prevention device is removed, relocated, repaired, or replaced. 4.3.10.7. INSTALLATION REQUIREMENTS Backflow devices shall be installed as described in the following sections, and as shown in the standard details. Public Works shall have the final authority in determining the required location of the backflow prevention device. 4.3.10.7.1. DOUBLE CHECK VALVE ASSEMBLY 1. Must be installed in a horizontal and level position, unless specifically designed for operation in a vertical position and tested and certified to be suitable for operation in that position by an approved backflow-testing laboratory. 2. Device should be installed as close as practical to the service connection, on the opposite side of the service connection from the public water system. 3. Device shall be above ground and, to the extent possible, not less than 12 inches or more than 36 inches above finished grade, as measured from the bottom of the assembly. 4. Device shall be easily accessible for maintenance and testing. 5. There must be no type of outlet, tee tap, take-off or connection to or from the service line between the service connection and the device. 6. Expansion tanks or pressure relief valves must be provided as appropriate for the potential threat of water hammer and thermal expansion. 7. Device may, if above-grade installation is impractical and the health authority approves, be installed in a below-grade vault such that: a. The top of the check valve assembly is not more than 8 inches below grade b. There is at least 12 inches of clearance between the bottom of the vault and the bottom of the device c. There is at least 24 inches of clearance between the side of the vault and the side of the double check assembly with test cocks a. There is at least 12 inches of clearance between the side of the vault and the other sides of the device b. To the extend warranted by climatic conditions, the device is protected from freezing c. The vault has adequate drainage to prevent the accumulation of water, which drains to daylight, to free-draining soil or to a sufficient amount of gravel placed under the vault to provide for free drainage and prevent he accumulation of water under the vault. A vault that does not have an integrated bottom must be placed on a layer of gravel which is not less than 3 inches deep. d. The vault is protected from vandalism e. The vault is not located in an area subject to vehicular traffic 8. The device may be installed indoors if the installation complies with items 1-7 inclusive, and has a clearance of: a. At least 12 inches on top b. At least 24 inches on the side with test cocks PW-10 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS c. At least 12 inches on the other sides 4.3.10.7.2. REDUCED PRESSURE PRINCIPLE ASSEMBLY 1. Must be installed in a horizontal and level position, unless specifically designed for operation in vertical position and tested and certified to be suitable for operation in that position by an approved backflow-testing laboratory. 4. Device should be installed as close as practical to the service connection, on the opposite side of the service connection from the public water system. 5. Device shall be above ground and, to the extent possible, not less than 12 inches or more than 36 inches above finished grade, as measured from the bottom of the assembly. 6. The site shall have adequate drainage, or drain piping, for any fluid that is discharged when the assembly is activated. 7. Device shall be installed such that no part of the assembly will be submerged during normal conditions of operation and weather. 8. Device shall be easily accessible for maintenance and testing. 9. Device must not be installed below grade, in any subsurface vault, or in any vault, chamber, or pit where there is any potential that the relief valve could become submerged. 10. Device shall have a free flowing drain with an air gap. 11. There must be no type of outlet, tee, tap, take-off, or connection to or from the service line between the service connection and the device. 12. Expansion tanks or pressure relief valves must be provided as appropriate for the potential threat of water hammer and thermal expansion. 13. The device may be installed indoors if the installation complies with sections 1- 10 inclusive, and has a clearance of: a. At least 12 inches on top b. At least 24 inches on the side with test cocks c. At least 12 inches on the other sides 4.3.10.7.3. AIR GAP 1. The air gap must be located as close as practical to the service connection, on the opposite side of the service connection from the public water system. 2. All piping from the service connection to the receiving tank must be above grade and visible. 3. There must be no type of outlet, tee, tap, take-off or connection to or from the service line between the service connections and the air gap. 4. Expansion tanks or pressure relief valves must be provided as appropriate for the potential threat of water hammer and thermal expansion. 4.3.11. DISINFECTION AND TESTING All water mains shall be disinfected and tested in accordance with AWWA C651 Standard for Disinfecting Water Mains. All water mains shall be pressure tested at 150 percent of the working pressure class or a minimum of 150 pounds per square inch; whichever is greater, in accordance with the “Standard Specifications for Public Works Construction.” PW-11 May 2008 ---PAGE BREAK--- City of Fernley Department of Public Works DESIGN STANDARDS 4.3.12. PRESSURE TESTING All PVC pipes shall be pressure tested in accordance with AWWA Standard C605. All ductile iron pipes shall be pressure tested in accordance with AWWA Standard C600. 4.3.13. LOCATING WIRE AND TAPE All buried, nonmetallic transmission, distribution and service pipes shall have a blue locating wire and a locating tape. The locating wire shall be installed and secured on the top of the pipe, and the locating tape shall be installed on top of the pipe bedding envelope. The tape shall bear a continuous message “Caution - Water Line Buried Below” or words of similar nature. The ends of the locating wire shall be accessible and extend into all valve boxes or other underground vaults. The locating wire shall be a minimum 12 gauge insulated copper wire. 4.3.14. ENCROACHMENT PERMIT The improvement plans shall clearly indicate that all work in Union Pacific Railroad, Bureau of Reclamation, and NDOT right-of-way requires an encroachment or occupancy permit from the respective entity. 4.3.15. PAVEMENT SAWCUT Refer to Pubic Works Standard Details regarding cutting of paved roads. Street excavation on streets which permanent surfacing is less than five years old is subject to a penalty fee. The penalty fee shall be 300% and reduce to 0% over 5 years from the date of acceptance of the surfacing. The penalty fee will start at 300% of the permit fee and reduce by 60% each year on the annual anniversity of the date of the surfacing acceptance. The fee will therefore be flat at 300% the first year, 240% the second year, 180% the third year, 120% the fourth year and 60% the fifth year. Developer must apply for a Street Cut Permit with Public Works prior to cutting an approved public street. PW-12 May 2008