B2_DRAFT_03.5_Section_C_Appendix_D_SLAC_Design_Procedures_Water_Services.pdf

DESIGN PROCEDURES - NEW WATER SYSTEMS

February 24, 2025

DESIGN PROCEDURES FOR NEW WATER SYSTEMS PIPING AND SERVICES

The following criteria have been established by SLAC Civil Engineering (SLAC CE) to guide consulting engineers in preparing studies, reports, and design documents for capital improvement and maintenance projects. Conformance to these guidelines is required, and these criteria should be considered as minimum design requirements.

These standards apply to the design and construction of the domestic water system only.

SLAC uses on average 150,000 gpd of domestic water via approximately 12-miles of pipeline.

Treated domestic potable water is supplied by the San Francisco Public Utilities Commission (SFPUC) via City of Menlo Park Water Department from two turn-outs, each serving the same pressure zone. To date, there are no booster pumps on the SLAC campus. Domestic potable water is provided for fire and potable uses via backflow prevention and check valves devices installed at various locations across the SLAC campus.

General Requirements and Process

1. SLAC’s Project Manager shall schedule an initial meeting with SLAC CE to review project water utility requirements and design guidelines prior to preparing and submitting plans for cost estimating or outside regulatory review.

2. Designs shall comply with current AWWA standards, California Department of Health Services regulations, California Plumbing Code (CPC), California Division of Drinking Water California Code of Regulations, and SLAC Facility Design Standards.

3. The water system layout shall be approved by SLAC CE. The fire hydrant layout shall be approved by the SLAC Fire Marshall’s Office (SLAC FM).

4. Minimum size water main shall be 6-inches in diameter and sized for the design fire flow.

5. All water main, services, and appurtenances shall be shown on the drawings in both plan and profile views and coordinated with requirements for all other proposed utilities, improvements (e.g., sub stations, radioactivity barriers, subterranean tunnels, etc.), and open areas. All water main piping and components and services shall be accessible for operation and maintenance and eventual replacement. Layout and locations of above ground appurtenances (e.g., backflow preventers, hydrants, etc.)

shall be reviewed and approved by SLAC CE and SLAC FM.

6. Calculations or computer modeling may be required for sizing more complicated water systems and for evaluating the impact on the existing systems, as determined by SLAC CE. Water mains shall be flushed, pressure tested, and disinfected prior to connection to the SLAC system and will conform to California Division of Drinking Water, AWWA 651, and SLAC’s Technical Specifications.

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7. SLAC domestic water mains will remain accessible for maintenance and repairs, as well as protected in delineated paved roadbeds for identification, monitoring, and future accessibility.

8. Refer to SLAC Sustainability Program for water conservation guidelines.

Water Demand Projection and Design Calculations

1. Design calculations submitted for District review shall be in a neat, acceptable form, and shall indicate the date, signature of the supervising engineer, and their State of California Engineering Registration Number and expiration date.

2. Prepare calculations of estimated domestic water demands for review and approval by SLAC CE. Calculations should include estimates for:

a. The Average Day, contact the SLAC CE for typical water usage for type of facility under consideration.

b. Maximum Day Demand is equal to twice the Average Day Demand.

c. Peak Hour Demand is equal to four times the Average Day Demand (twice the

Maximum Day Demand).

3. Water demand for buildings will be subject to the SLAC’s Sustainability Goals.

Flow Requirement

The following are basic requirements only. For detailed fire flow requirements, please contact the SLAC Fire Marshall (FM) for current guidelines and specifications.

1. Maximum allowable service pressure measured at a faucet is 80 pounds per square inch

(psi); minimum service pressure shall be 35 psi.

2. Flow velocities shall be in the range of 4-7 feet per second (fps), but in no case shall exceed

10 fps.

3. Fire flows and pressures shall be approved by the SLAC FM.

a Reductions in the Fire flow requirement must be approved by the SLAC FM.

b Contact the SLAC FM for estimates of static system water pressures in the vicinity of the project.

c Use of fire booster pumps must be justified, and justification must be approved by the SLAC FM.

4. Only the SLAC FM releases hydrant flow test data for design purposes.

a Submit request for hydrant flow testing to the F&O Fire Protection Systems Group.

Only the SLAC FM releases hydrant flow test data for design purposes. The actual flow tests are typically conducted by F&O Fire Protection Systems Group.

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Alignment

1. New potable water mains and new potable service lines shall not be installed in the same trench as, and shall be at least 10 feet horizontally from and one foot vertically above, any pipeline conveying:

a. Untreated sewage,

b. Primary or secondary treated sewage,

c. Disinfected secondary recycled water (as defined in California Code of Regulations

Section 60301.220 and 60301.225), and

d. Other fluids, including hazardous fluids such as fuels, industrial wastes, wastewater sludge, etc..

2. Approval is required by SLAC CE, of any new potable water mains and new potable supply lines installed closer than 4-feet horizontally from, and one foot vertically above, any pipeline conveying:

a. Disinfected tertiary recycled water (as defined in California Code of Regulations Section 60301.230), and

b. Storm drainage.

3. If crossing a pipeline conveying a fluid listed above in subsection 1 or 2, a new water main shall be constructed no less than 45-degress to and at least one foot above that pipeline. No connection joints shall be made in the domestic water main within 8-feet horizontal separation from the fluid pipeline. A pipe sleeve shall also be considered.

4. Horizontal and vertical clearance from other pipelines shall be measured from inside edge of pipe to inside edge of pipe to result in the maximum separation. Where these minimum separations are not feasible, consult with the SLAC Civil Engineer.

5. If a 10-foot horizontal separation is not practical, a separation of at least 4-feet may be allowed subject to special construction conditions. In no case is horizontal separation of less than 4-feet or construction in the same trench as potable pipes and appurtenances allowed. Where these minimum separations are not feasible, consult with the SLAC Civil Engineer for guidance, including the use of an unbreeched or continuous pipe sleeve which extends a minimum of 10-feet on either side of the potable water piping crossing.

6. Domestic water main separation from other underground pipelines shall comply with the California Code of Regulations Title 22, Division 4, Chapter 16, Article 4, Section 64572 Water Main Separation.

7. In paved areas, minimum cover shall be 42-inches from finished grade to top of pipe, or 2-feet below subgrade, whichever is greater. If approved by SLAC CE, water supply lines placed in unpaved areas shall require a minimum cover of 36-inches from finished grade to top of pipe. If these minimum covers are not feasible, consult with the SLAC CE for pipe material alternatives and requirements.

8. Gate valves shall be installed to isolate each branch run from the water supply main. Valves shall be Mueller Resilient wedge gate valves, unless approved by SLAC CE.

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9. Tapping sleeve branch connections from existing mains shall be used only by prior approval by SLAC CE. No same line size tapping sleeves will be allowed.

10. Combination Air-Vacuum Release Valve (CAVRV): Air release/vacuum relief valves shall conform to AWWA C512 and will be installed at high points and at significant changes in grade in the water system profile. If field conditions require changes in grade shown in the water system hydraulic profile, provided by the designer, SLAC CE shall review proposed sizes and locations of air release/vacuum relief valves during design and construction.

a. Corporation stops (for use with air release valve connections): Corporation stops shall be two inches (2-inches) size, cast bronze body, plugs, and trim, and IP threaded for saddles, Mueller H-15023, no substitutions.

b. Air release/vacuum relief valve pipe shall be 1-inch diameter for mains 12 inches in diameter or smaller, or 2-inch diameter for all other sized mains.

c. Air release/vacuum relief valve opening shall be screened against intrusion of insects with a Northtown HYTECH Air Vac (Bug) Screen, 20 MESH.

11. Blow off valve assemblies shall only be permitted in temporary locations and shall be #78 Mainguard Hydrants or approved equal. All installations where a permanent blow-off is required shall be accomplished through the use of a standard fire hydrant.

12. No potholing and excavation shall be allowed with vacuum trucks unless a SLAC Excavation Permit has been obtained by the SLAC Project Manager and work approved by

SLAC CE.

13. Under no circumstances will potable water or sewer mains or service laterals be conveyed under building foundations or permanent structures.

Materials

1. Pipeline material for domestic water mains shall be Polyvinyl Chloride (PVC) C900 DR- 14 and must conform to SLAC’s Technical Specifications.

2. Domestic water valves, burys, and fittings shall be ductile iron and fusion epoxy coated and lined, conforming to SLAC’s Technical Specifications (Mueller Resilient Wedge Gate Valves or equivalent). Non-PVC joints and valves will be poly-wrapped and taped with 10 mil.

tape (Black Plastic PVC or PE Pressure-Sensitive Corrosion Preventive Tape (UPC IAPM PS 37- 1990) or plastic straps to supplement corrosion protection.

3. HDPE SDR11 maybe used for some unusual crossings, like a river or difficult road cut. In this case, directional drilling will be considered.

Cathodic Protection

1. All metallic water mains, fittings and services shall have cathodic protection using a sacrificial anode system. The system designed will be easily maintained and approved by the SLAC CE.

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2. All metallic services connecting to non-metallic water mains shall have cathodic protection using a sacrificial anode system. The system designed will be associated with the water service and easily maintained by the Building, as approved by the SLAC CE.

3. Soils shall be tested for corrosivity using the procedures described in Appendix "A" of AWWA C-105. Any soil having a soil-test evaluation of 10 points or more shall require the use of cathodic protection. Testing will be at the Project/owner expense and test results will be provided to SLAC CE for review.

Water Services

1. Carbon steel/galvanized/cast iron building services are prohibited. Metallic building services entering the building/structure shall be copper or ductile iron.

2. Minimum water service size shall be one inch.

3. Services 4-inches and larger shall be installed by the project using tee connections with isolation line valves on the main on both sides of the branched connection to allow isolation and replacement.

4. Tapping sleeve connections shall be used only by prior approval of SLAC CE. No same line size tapping sleeves will be allowed.

5. If the service pressure exceeds the maximum of 80 psi, an individual Pressure Regulating/Reducing Valve (PRV) will be required on the service line after the meter and backflow. Pressure Reducing Valves (PRV) shall be a combination pressure reducing and pressure sustaining, Cla-Val Model 92-01. No comparable products or equals shall be allowed due to standardization requirements. Properly designed CAVRVs shall be installed immediately downstream of all PRVs.

6. Meter boxes shall be located where they are easily accessible to the meter reader, in the sidewalk or 18-inches behind and set parallel with the curb. Meters may not be closer than 3-feet to a driveway or parking spaces, in order to avoid being obscured by parked vehicles.

7. Water services shall not be located closer than 5-feet from a sewer lateral, with a minimum of 30-inches of cover.

8. All meters, detector meters and radio read assemblies are to be supplied and installed by the Project.

9. Water meter transmitters shall be LoRaWAN wireless antenna, Mueller MSW-NODE5-05.

10. Debris caps shall be installed in all valve boxes and conform to SLAC’s Technical

Specifications.

Buried Pipe Restraints

1. All new main line piping shall be designed as self-restrained against thrust forces. Refer to SLAC Facility Design Standard 33 10 01 for Domestic Water Systems for acceptable materials.

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2. Thrust blocks shall be designed for a minimum operating pressure of 250 psi, based on design soil bearing pressure as determined by the SLAC Project Manager and SLAC contracted Geotechnical Engineer.

3. Thrust blocks shall not bear on soil more than 1-foot above the pipe nor against soil with other utilities within 5-feet.

Backflow Prevention Assembly

1. All water supply services to new, renovated, or remodeled buildings shall be provided with approved dual backflow prevention assemblies. Backflow prevention assembly shall be a Reduced Pressure Principal Backflow Prevention Assembly (RPP BFP). Refer to FDG standard specification and details for current acceptable models.

2. The type of backflow preventer assembly will be determined by SLAC FM for fire related applications and SLAC CE for other domestic connections depending on whether the building use is deemed to be a low hazard potential or whether dangerous or toxic substances are involved.

3. Backflow prevention assemblies shall be approved by AWWA and shall bear the stamp of Underwriters Laboratories (U.L.).

4. Proposed sizes and locations of backflow prevention assemblies shall be reviewed and approved by the SLAC CE and SLAC FM.

References

1. American Water Works Association (AWWA) C104, C105, C111, C115, C151, C153, C219, C502, C503, C504, C509, C512, C600, C605, C651, C800, C900, C905.

2. California Division of Drinking Water, California Code of Regulations – Title 17, Public Health, and Title 22, Social Security

3. California Plumbing Code, latest edition

4. SLAC Fire Marshal Standards FH-1 through FH-6. DRAFT