9-15Irrigation System

9-15 Irrigation System9-15 Irrigation System

All materials and equipment incorporated in the system shall be new, undamaged, of standard quality, and shall be subject to testing as specified. When the water supply for the irrigation system is from a nonpotable source, irrigation components shall have lavender indicators supplied by the equipment manufacturer.

9-15.1 Pipe and Fittings

Pipe shall be copper, galvanized iron, PVC, or polyethylene, as specified in the Plans or in the Special Provisions.

9-15.1(1) Galvanized Pipe and Fittings

Pipe shall be standard weight, hot-dip galvanized iron or steel pipe, threaded and coupled. Pipe shall meet the requirements of ASTM A53. All pipe fittings shall be standard threaded galvanized malleable iron fittings.

9-15.1(2) Polyvinyl Chloride Pipe and Fittings

PVC pipe and fittings shall be of PVC compound Type 1, Grade 1, conforming to ASTM D1785 Specifications. The pipe and fittings shall be approved and certified by the National Sanitation Foundation. The Engineer may require dimensional and quick burst tests of pipe and fittings after arrival at the job site. Acceptance of the materials shall be subject to passing the designated tests per ASTM Standards. PVC solvent weld pipe shall be of PVC 1120 material and shall have 200 psi minimum pressure rating with SDR 21 walls which conform to ASTM D2241. PVC pipe with walls heavier than SDR 21 shall be installed when noted in the Plans and specified in the Special Provisions. PVC threaded pipe shall be of PVC 1120 material and shall be schedule 80 which conforms to ASTM D1785. PVC pipe fittings shall conform to ASTM D2466, Type I, Grades 1 or 2. Pipe may be belled on one end with the dimensions of the tapered bell conforming to ASTM D2672. Each length of PVC pipe is to be marked with an identifying extrusion “run” number and the manufacturer’s name or trade name plus the pipe size and schedule. Acceptance of the materials shall be subject to approval by conforming to the designated tests in accordance with ASTM Standards following the table below. Type Minimum Requirements PVC pipe – Schedule 40, 80 and 120 ASTM D1785; Compounds following ASTM D1784, PVC 12454 or 143333 PVC pipe – SDR 21 (Class 200) ASTM D2241; Compounds following ASTM D1784, PVC 12454, 14333 PVC Fittings – Schedule 40 ASTM D2466; Compounds following ASTM D1784, PVC 12454, 13354,11443 or 14333 PVC Fittings – Schedule 80 ASTM D2467, ASTM D2464; Compounds following PVC 12454, 11443, 14333

9-15.1(3) Polyethylene Pipe

Polyethylene pipe shall be SDR 15, medium density polyethylene, meet the following requirements of ASTM D2239, PE1404, PE2708, PE3608, PE4608, or PE4710, and be National Sanitation Foundation (NSF) certified. Thick walled polyethylene (poly) pipe shall be used in conjunction with fittings recommended by the manufacturer of the poly pipe to produce a flexible swing joint assembly between the lateral line and the irrigation sprinkler. The pipe shall be manufactured from high quality, low density virgin polyethylene material and have a M 41-10 Page 9-103 Irrigation System 9-15minimum wall thickness of 0.10 inch and a minimum inside diameter of 0.49 inch. The pipe shall be capable of withstanding 80 psi operating water pressure at 110°F. The length of thick walled poly pipe at each flexible swing joint assembly shall be 18 inches minimum to 36 inches maximum.

9-15.2 Drip Tubing

Drip tubing shall be manufactured from specially formulated, chemical resistant, low to medium density virgin polyethylene or polybutylene selected for excellent weatherability and stress cracking resistance and designed specifically for use in drip irrigation systems. Drip tubing shall have a minimum wall thickness of 0.045 inch.

9-15.3 Automatic Controllers

Automatic controllers shall be an electronic timing device for automatically opening and closing control valves for predetermined periods of time. The automatic controller shall be enclosed in a weatherproof painted metal housing fabricated from 16 gauge sheet aluminum alloy 6061-T6 or 16-gauge sheet steel or unpainted, nonrusting industrial grade stainless steel or as specified in the Plans. The pedestal shall have a completely removable locking faceplate to allow easy access to wiring. The automatic controller housing shall have a locking device. All locks or locking devices shall be master keyed. The controller shall be compatible with and capable of operating the irrigation system as designed and constructed and shall include the following operating features:

9-15.4 Irrigation Heads

Irrigation heads shall be of the type, pattern, and coverage shown in the Plans at rated operating pressure specified. Sprinkler heads shall be designed so that spray adjustments can be made by either an adjustment screw or interchangeable nozzles. Watering cores shall be easily removed without removing the housing from the pipe. All instructions, special wrenches, clamps, tools, and equipment supplied by the manufacturer necessary for the installation and maintenance of the irrigation heads shall be turned over to the Engineer upon completion and acceptance of the project.

9-15.5 Valve Boxes

Valve box sizes and types shall conform to the Plans and be extendable to obtain the depth required. All manual drain valves and manual control valves shall be installed in valve box with a vandal-resistant lid as shown in the Plans. Page 9-104 M 41-10

9-15 Irrigation System9-15.6 Gate Valves

Gate Valves shall be of the same size as the pipes on which they are placed and shall have union or flange connections. Service rating (for nonshock cold water) shall be 150 psi. Gate Valves shall be of the double disk, taper seat type, with rising stem, union bonnet and hand wheel or suitable cross wheel for standard key operation. Manufacturer’s name, type of valve, and size shall be imprinted or printed on the valve.

9-15.7 Control Valves

9-15.7(1) Manual Control Valves

Manual control valves shall be of the same size as the pipes connecting into them unless specified otherwise in the Plans. Service rating shall be not less than 150 psi nonshock cold water. When bronze is specified, the body shall follow ASTM B62. Brass body, ball and stem shall follow ASTM B16 or ASTM B124 (377). All plastic manual valves shall be pressure rated minimum of 125 psi and ASTM D1784. Socket dimensions shall follow ASTM D2467. Threaded dimensions shall follow ASTM D2464. Manual control valves shall be designed for underground installation with suitable cross wheel for operation with a standard key and installed in a valve box. Manual control valves shall have removable bonnet and stem assemblies with adjustable packing glands and shall house long acme threaded stems to ensure full opening and closing.

9-15.7(2) Automatic Control Valves

Automatic remote control valves shall be globe pattern and glass filled nylon with flanged or screwed connections as required. The automatic control valve shall be constructed so as to allow all internal parts to be removable from the top of the valve without disturbing the valve installation. Automatic control valves shall be of a normally-closed design and shall be operated by an electronic solenoid having a maximum rating of 6.5 watts utilizing 24-volt AC power with 50/60 Hz. Electronic solenoids shall have a stainless steel plunger and be directly attached to the valve bonnets or body with all control parts fully encapsulated. Automatic control valves shall be 20-200 psi. The opening and closing speed of the valve shall be a minimum of five seconds for closure and a minimum of three seconds for opening with a constant rate of opening and closing. A manual control bleed cock shall be included on the valve to operate the valve without the requirement of electrical current. A manual shutoff stem with cross handle for wrench operation is required for manual adjustment from fully closed to wide open. Once the manual adjustment is set, the valve shall operate automatically in the adjusted position. Water flow shall be completely stopped when the control valve is closed either manually or automatically. Automatic control valves and automatic controllers need not be from the same manufacturer.

9-15.7(3) Automatic Control Valves with Pressure Regulator

Automatic control valves with pressure regulators shall be similar to the automatic control valves described in Section 9-15.7(2) and shall reduce the inlet pressure to a constant pressure regardless of supply fluctuations. The regulator shall be fully adjustable.

9-15.8 Quick Coupling Valves

Quick coupler valves shall have an operating range between 5 to 125 psi. The body of the valves shall be of cast Copper Alloy No. C84400 Leaded Semi-Red Brass conforming to ASTM B584. The base of the valve shall have standard female pipe threads. The design of the valve shall be such that it will open only upon inserting a coupler key and will close as the coupler key is removed from the valve. Leakage of water between the coupler and valve body when in operation shall not be accepted. The valve body receiving the coupler key shall be designed with double worm slots to allow smooth action in opening and closing of the valve with a minimum of effort. Slots shall be notched at the base to hold M 41-10 Page 9-105 Irrigation System 9-15the coupler key firmly in the open position. Couplers shall be of the same material as the valve body with stainless steel double guide lugs to fit the worm slots. Couplers shall be of one-piece construction with steel reinforced side handles attached. All couplers shall have standard male pipe threads at the top. Couplers shall be furnished with all quick coupler valves unless otherwise specified.

9-15.9 Drain Valves

Drain valves shall be a ½- or ¾-inch PVC or metal gate valve manufactured for irrigation systems. Drain valves shall be designed for underground installation with suitable cross wheel for operation with a standard key, shall have a service rating of not less than 150 psi nonshock cold water, and shall be installed in a valve box. Drain valves on potable water systems shall only be allowed on the downstream side of approved cross-connection control devices.

9-15.10 Hose Bibs

Hose bibs shall be angle type, constructed of bronze or brass, threaded to accommodate a ¾-inch hose connection, and shall be key operated. Design shall be such as to prevent operation by wrench or pliers.

9-15.11 Cross Connection Control Devices

Atmospheric vacuum breaker assemblies (AVBAs), pressure vacuum breaker assemblies (PVBAs), double check valve assemblies (DCVAs), and reduced pressure backflow devices (RPBDs) shall be of a manufacturer and product model approved for use by the Washington State Department of Health, Olympia, Washington, or a Department of Health-certified agency.

9-15.12 Check Valves

Adjustable spring check valves shall be PVC and shall be pressure rated at 200 psi. Valves shall be adjustable from 5 to 15 pounds spring tension but shall not cause pressure loss in excess of 5 psi for flows up to 30 gpm. Valves shall have angled seats, Buna-N seals, and threaded connections, and shall be installed in 8 inch round plastic valve boxes with vandal-resistant lids.

9-15.13 Pressure Regulating Valves

Pressure regulating valves shall have a minimum of 150 psi working pressure with an adjustable outlet range of 20 to 70 psi. The valves shall be factory set as shown in the Plans. Pressure regulating valves shall be rated for safe operation at 175 psi nonshock cold water.

9-15.14 Three-Way Valves

Three-way valves shall be tight closing, three port, ball or plug type, constructed to permit straight through and 90-degree flow only. The valve shall be of bronze or approved corrosion resistant body materials and shall have a minimum of 150 psi working pressure. The head of the valve, or handle when applicable, shall be permanently marked to indicate port position.

9-15.15 Flow Control Valves

Valve body materials shall be plastic or metal. Internal parts shall be stainless steel. Valves shall be factory set to the flows as shown in the Plans. Valves shall have no external adjustment and be tamper-proof when installed. Control valves 1/4 inch or smaller shall have a minimum pressure absorption range of 2 to 32 psi. Larger flow control valves 11/2 inch or larger shall have a minimum pressure absorption range of 3 to 50 psi. Flow shall be controlled to 5 percent of Plan volumes. Page 9-106 M 41-10

9-15 Irrigation System9-15.16 Air Relief Valve

The air relief valve shall automatically relieve air and break a vacuum in the serviced pipe. Body materials shall be installed exactly at all high points.

9-15.17 Electrical Wire and Splices

Electrical wire used between the automatic controller and automatic control valves shall be solid or stranded copper, minimum size AWG 14. Insulation shall be Type USE Chemically Cross Linked Polyethylene or Type UF, and shall be listed by a Nationally Recognized Testing Laboratory. Each conductor shall be color coded and marked at each end and at all splices with zone or station number identification. Low voltage splices shall be made with a direct bury splice kit using a twist-on wire connector and inserted in a waterproof polypropylene tube filled with a silicone electrical insulating gel or heat-shrinkable insulation tubing. Heat-shrinkable insulation tubing shall consist of a mastic-lined heavy-wall polyolefin cable sleeve.

9-15.18 Detectable Marking Tape

Detectable marking tape shall consist of inert polyethylene plastic that is impervious to all known alkalis, acids, chemical reagents, and solvents likely to be encountered within the soil, with a metallic foil core to provide for the most positive detection and pipeline location. The tape shall be color coded and shall be imprinted continuously over its entire length in permanent black ink indicating the type of line buried below and shall also have the word “Caution” prominently shown. Color coding of the tape shall be as follows: Utility Tape Color Water Blue Sewer Green Electrical Red Gas/Oil Yellow Telephone/CATV Orange Non-Potable Water Purple The width of the tape shall be as recommended by the manufacture based on depth of installation.

9-15.19 Wye Strainers

Wye strainers shall be bronze or brass with screwed end connections, 20 mesh Monel or stainless steel screen, and standard tapped bronze retainer cap and closure plug. Service rating shall be not less than 150 psi nonshock cold water.