Chapter 15.40
PRESSURIZED IRRIGATION
Sections:
15.40.040 Valves and couplings.
15.40.050 Meters, boxes and services.
15.40.010 General.
A. Specifications. This chapter covers the installation of pressurized irrigation lines. See standard drawings related to pressurized irrigation.
B. Pipe. Polyvinyl chloride (PVC) pipe shall be used for all pressurized irrigation mains unless authorized by the city engineer or his/her designee.
C. Size. The city must approve the sizes of all proposed pressurized irrigation lines. The minimum size of pressurized irrigation pipe is six inches in diameter for main lines and one inch in diameter for services.
D. Location. Pressurized irrigation mains shall be located along centerline. Pressurized irrigation may not be placed in same trench as waterline. [Ord. O-09-2024 § 2 (Exh. A); Ord. O-03-2010 § 1 (Exh. A § 8.010)].
15.40.020 Installation.
A. General. Pressurized irrigation distribution and transmission systems shall be installed according to the requirements and specifications of APWA 02510. PVC pipe shall also be installed according to the requirements and specifications of AWWA C605.
B. Pipe Cleanliness. All foreign matter or dirt shall be removed from the inside of the pipe before it is placed and it shall be kept clean during and after laying. No debris, tools, or other materials shall be placed in the pipe during laying operations. When laying of pipe is not in progress, the pipe shall be closed by a watertight plug.
C. Minimum Cover. All pressurized irrigation mains shall have a minimum cover of three feet to the top of the pipe.
D. Identification Tape. All pressurized irrigation mains shall be installed with identification tape that meets the requirements and specifications of APWA 02320. Tape shall be buried 12 inches below grade.
E. Lateral Displacement. All pipes shall be protected from lateral displacement resulting from impact or unbalanced loading during backfilling operations.
F. Restraining. Either thrust blocks or mechanical retaining devices shall be used for all tees, valves, plugs, caps, and bends. Restraining shall be accomplished according to the standard drawings.
G. Connection to Existing Pressurized Irrigation Lines. The contractor will be responsible to verify actual size, type of material, and location of existing utilities in the field. The fittings and materials required for construction must be approved by the city engineer or his/her designee. Where fitting sizes, such as tees and crosses, are shown on the plans, those sizes will be used. However, no attempt has been made to show all needed fittings or materials.
H. Drains shall be installed at all low points on pressurized irrigation and connected to storm drain inlets. Pipes shall be sloped to low points to allow drainage. [Ord. O-09-2024 § 2 (Exh. A); Ord. O-03-2010 § 1 (Exh. A § 8.020)].
15.40.030 Pipe and fittings.
A. General. Polyvinyl chloride (PVC) pipe shall be used for all pressurized irrigation mains 12 inches in diameter and smaller unless otherwise authorized by the city engineer or his/her designee. Ductile iron or polyethylene pipe shall be used for pressurized irrigation mains larger than two inches in diameter. Only PVC or polyethylene pipe may be used in corrosive soils.
B. Polyvinyl Chloride (PVC) Pipe. PVC pipe shall meet the requirements and specifications of APWA 15014 and AWWA C900, C905, and C909. Only purple, pressure class 150 psi pipe may be used for pressurized irrigation mains.
C. Ductile Iron Pipe. Ductile iron pipe shall meet the standards and specifications of APWA 15011. Only a pressure class of 150 psi or larger may be used. A tubular purple polyethylene encasement must be installed according to AWWA C105 over all ductile iron pipe and fittings. Flanges, when required, shall meet the requirements and specifications of AWWA C115.
D. Polyethylene Pipe. Polyethylene pipe shall meet the standards and specifications of APWA 15013.
E. Steel Pipe – Lined and Coated. Steel pipe shall meet the standards and specifications of APWA 15010.
F. Fittings. Use ductile iron fittings that conform to the provisions of ANSI/AWWA C110/A21.10 or C153/A21.53 unless otherwise recommended by the manufacturer and authorized by the city engineer or his/her designee. All PVC pipes being inserted into fittings shall have the bevel end removed. All the bolts and nuts of all the fittings shall be greased. All fittings shall have an eight-millimeter vinyl wrap plastic cover. [Ord. O-09-2024 § 2 (Exh. A); Ord. O-03-2010 § 1 (Exh. A § 8.030)].
15.40.040 Valves and couplings.
A. General. All valves shall meet the requirements of APWA 02510 and 15030.
B. Resilient Seated Gate Valve. All valves on six-inch to 10-inch water mains shall be resilient seated gate valves. Valves shall also be of iron body, have nonrising bronze stems and meet the following specifications:
1. Mechanical Joint. When valves are mechanical joint, they shall be furnished with all necessary glands, followers, and bolts and nuts to complete installation.
2. Valve Stems. Bronze valve stems shall be interchangeable with stems of the double disc valves of the same size, direction of opening and manufacture.
C. Butterfly Valve. All valves 12 inches and larger shall be butterfly valves which meet the requirements and specifications of APWA 02510, 15030 and the following specifications:
1. General. Valve bodies shall be cast iron, ASTM A126, Class B. Body ends shall be flanged with facing and drilling in accordance with ANSI B16.1, Class 125; or mechanical joint in accordance with AWWA C111. All mechanical joint end valves shall be furnished complete with joint accessories (bolts, nuts, gasket, and glands). All valves shall conform with AWWA Standard C504, Table 3, Laying Lengths for Flanged Valves and Minimum Body Shell Thickness for All Body Types.
2. Disc. Valve disc shall be ductile iron ASTM A536, Grade 65-45-12. Valve disc shall be of the offset design providing 360-degree uninterrupted seating.
3. Shaft Bearings. Shaft bearings shall be contained in the integral hubs of the valve body and shall be self-lubricated sleeve type.
4. Coating. All valves shall be coated with epoxy in conformance to AWWA Standard C550, latest revision.
Interior wetted ferrous surfaces shall be coated a nominal 10 mils thick for long life, and body exterior shall have a minimum of three to four mils coating thickness in order to provide superior base for filed-applied finish coats.
D. Valve Boxes. All buried valves shall be installed complete with two-piece, cast iron, slip-type, five-and-one-quarter-inch shaft valve box with drop lid. The lid shall have the word “IRRIGATION” or “DRAIN” according to the standard drawing cast in the metal.
Valves and valve boxes shall be installed where shown on the drawings. Valves and valve boxes shall be set plumb. Valve boxes shall be centered directly over the valve. Valves shall be aligned with property lines where possible. Earth fill shall be carefully tamped around the valve box to a distance of four feet on all sides of the box, or to the undisturbed trench face if less than four feet. Valves shall have the interiors cleaned of all foreign matter before installation.
All tops of valve boxes located in streets shall be installed one-quarter inch below grade. When a one-inch overlay is required a year after the road construction, the pavement surrounding the valve box shall be neatly cut to form a 30-inch round opening with the valve box centered, and a concrete collar shall be cast around the box. Valve boxes in off-road areas shall extend six inches above grade. Lid detail shall be similar to Comco C6517.
E. Couplings. Couplings shall be equal to the product of Smith-Blair or Dresser with cast iron couplings being used on all cast iron and PVC pipe. Couplings shall be straight, transition, or reducing style as required by the specific installation. All steel fittings and bolts shall be coated with a nonoxide coating and wrapped with polyethylene.
F. Pressure Regulation Valves. Pressure regulation valves (PRV) which are required in a development shall be designed by the developer’s engineer and the design shall be submitted to the city engineer or his/her designee for review and approval prior to starting construction. All PRVs shall be Cla-Val with bypass, be placed in a concrete vault and have telemetry included.
G. Tapping Valves. Tapping valves may only be used when previously approved by the city engineer or his/her designee. Tapping saddles with an “O” ring may be used if the water main line to be tapped is larger than the new water main line. Where the tap is the same size as the existing main, cast iron or stainless steel tapping sleeves shall be used which encase the full perimeter of the pipe. The valve shall be a tapping valve with a guide lip on the flanged side. The opposite side of the valve shall have a mechanical joint connection.
H. Air Vacuum and Release Valves. Combination air, vacuum and release valves shall be installed according to the standard drawings at high points in the system as required by the city. [Ord. O-09-2024 § 2 (Exh. A); Ord. O-03-2010 § 1 (Exh. A § 8.040)].
15.40.050 Meters, boxes and services.
A. General. See the standard drawings for pressurized irrigation services. The minimum size of new pressurized irrigation service lines is one inch IP. Pressurized irrigation services shall be installed after electrical services. Every lot, including both sides of a twin home lot, shall have its own pressurized irrigation service.
B. Placement and Location. All meters and boxes shall have their location and grade staked prior to installation. No meters or boxes shall be set in sidewalks or driveways. Service taps shall be a minimum of 36 inches apart. No taps will be allowed within 36 inches of the end of the pipe. Service laterals shall extend perpendicular from the main to the meter box. For dual pressurized irrigation services, laterals shall extend perpendicular from the main to the tee. If a meter must be moved it may only be displaced a maximum of 24 inches to either side. If it must be moved more than 24 inches, a new service line must be installed. When a new service line is installed, the old corporation stop shall be shut off at the main and the old service line cut two feet from the main.
C. Meters and Boxes. All meters shall be paid for by the developer and purchased by the city. Meter boxes and pressurized irrigation boxes shall be in good repair. They shall not set at an angle or in a crushed or dented condition. The inside of boxes must be free of obstructions such as dirt, rocks or debris. Meters shall be installed by the developer or contractor.
D. Polyethylene Pipe. Only CTS SDR9 200 psi purple polyethylene pipe shall be used for pressurized irrigation service lines. Pipe damaged by scratches, cuts, kinks or buckled areas shall not be installed. The bottom of the trench shall be flat with no hollows, no lumps and no rock. If these conditions do not occur, pipe must be bedded in coarse sand. No rocks shall be allowed within six inches of pipe. Pipe shall be cut with either a wheel- or scissor-type tubing cutter with a blade specifically designed for plastic. Cuts shall be square and clean. Cutter manufacturer instructions shall be followed when cutting pipe. All connections shall have stainless steel stiffeners. There shall be no unnecessary bending of pipe. Taps shall be exactly horizontal to the pressurized irrigation main. If bending cannot be avoided, maximum bending radius shall be 25 times the pipe diameter. There shall be no bending within three feet of a fixed point and no “S” shape curves. [Ord. O-09-2024 § 2 (Exh. A); Ord. O-03-2010 § 1 (Exh. A § 8.050)].
15.40.060 Flushing.
A. General. All pressurized irrigation lines shall be flushed before being placed in service. Flushing shall be accomplished through the end of each line.
B. Velocity. The contractor shall install a tap sufficient in size to provide for two-and-one-half-foot-per-second flushing velocity in the line. The following is the flow quantity required to provide a two-and-one-half-foot-per-second flushing velocity:
|
FOR FLUSHING (pipe diameter) |
FLOW REQUIREMENTS (flow in gallons per minute) |
|---|---|
|
4 inches |
100 |
|
6 inches |
220 |
|
8 inches |
390 |
|
10 inches |
610 |
|
12 inches |
880 |
|
16 inches |
1,567 |
|
18 inches |
1,980 |
|
20 inches |
2,450 |
|
24 inches |
3,525 |
|
30 inches |
5,507 |
[Ord. O-09-2024 § 2 (Exh. A); Ord. O-03-2010 § 1 (Exh. A § 8.060)].