6.20.330 Materials and installation.
(1) Water Mains and Fittings. Water mains to be installed shall be ductile iron pipe for all sizes, unless otherwise approved by the district. PVC C900 DR 18 or HDPE DR 9 pipe may be used for water mains when approved by the district and warranted, such as installation by directional drilling, corrosive environments, or in the vicinity of electrical transmission lines.
All ductile iron water pipe shall be delivered to the site with wrapping to cover the ends of the pipe or with pipe plugs. Either method used shall remain in unbroken condition until the pipe is installed.
The ductile iron pipe shall conform to AWWA C151 and shall be Class 52. The pipe shall be cement lined to a minimum thickness of one-sixteenth-inch meeting NSF standards for potable water and the exterior shall be coated with an asphaltic coating.
Each length shall be plainly marked with the manufacturer’s identification and class of pipe. The pipe shall be furnished with mechanical joint or push-on type joint, except where plans call for flanged ends. Joints shall conform to AWWA C111.
Restrained joint pipe shall be used on all public water mains unless otherwise approved by the district. Restrained joint pipe shall be push-on joint pipe with Field Lok, TR Flex or district approved equal gaskets.
All pipe shall be joined by the manufacturer’s standard coupling, be all of one manufacturer, and be carefully installed in complete compliance with the manufacturer’s recommendations. Welded HDPE pipe connections and joints shall only be made by certified personnel.
Joints shall be “made up” in accordance with the manufacturer’s recommendations. Standard joint materials, including restrained gaskets, shall be furnished with the pipe. Material shall be suitable for the specified pipe size and pressures.
All fittings shall be short-bodied, ductile iron complying with AWWA C110 or C153 for 350 psi pressure rated mechanical joint fittings and 250 psi pressure rated flanged fittings. All fittings shall be cement mortar lined per the ductile iron pipe specifications and either mechanical joint or flanged.
A locate box per district standard details shall be installed on water mains located in unpaved easement areas at each bend and/or every 300 feet.
Fittings in areas requiring restrained joints shall be mechanical joint fittings with a mechanical joint restraint device. The mechanical joint restraint device shall have a working pressure of at least 250 psi with a minimum safety factor of 2:1 and shall be EBAA Iron, Inc., MEGALUG, or approved equal.
All couplings shall be restrained joint ductile iron mechanical joint sleeves.
The pipe and fittings shall be inspected for defects before installation. All lumps, blisters and excess coating shall be removed from the bell and spigot end of each pipe, and the outside of the spigot and the inside of the bell shall be wire-brushed and wiped clean and dry, and free from oil and grease before the pipe is laid.
Every precaution shall be taken to prevent foreign material from entering the pipe or joint while it is being placed in the line. At times when pipe laying is not in progress, the open ends of pipe shall be closed by a watertight plug. If water is in the trench when work resumes, the seal shall remain in place until the trench is pumped completely dry. No pipe shall be laid in water or when trench conditions are unsuitable.
The cutting of pipe for inserting fittings or closure pieces shall be done in a neat and workmanlike manner, without damage to the pipe or cement lining, and so as to leave a smooth end at right angles to the axis of the pipe. When a pipe length is cut, the outer edge of the cut shall be beveled to prevent damage to the gasket during jointing of the pipes.
Pipe shall be laid with bell ends facing uphill in the direction of the laying, unless approved otherwise by the district. Pipes shall be at grade prior to inserting the spigot into the bell. After placing a length of pipe in the trench, the spigot end shall be centered in the bell and pipe forced home prior to any final deflection adjustments. Wherever it is necessary to deflect pipe from a straight line, the amount of deflection allowed shall not exceed pipe manufacturer’s recommendations. The pipe shall be secured in place with compacted select backfill in accordance with district standard details.
For connection of mechanical joints, the socket, plain end of each pipe and gasket shall be cleaned of dirt before jointing and shall be jointed according to manufacturer’s directions. Bolts shall be tightened alternately at top, bottom, and sides, so pressure on gasket is even.
For connection of push-on type joints, the jointing shall be done according to manufacturer’s recommendations, with special care used in cleaning gasket seat to prevent any dirt or sand from getting between the gasket and pipe. Lubricant to be used on the gasket shall be nontoxic and free from contamination.
Valves, fittings, plugs, and caps shall be set and jointed to pipe in the manner as required. All dead ends on new mains shall be closed with mechanical joint caps.
Fittings at horizontal and vertical bends shall be anchored with thrust blocks made of cast-in-place 3,000 psi strength concrete, with a firm minimum bearing against an undisturbed earth wall. Timber blocking will not be permitted. The concrete thrust blocks shall be in place and cured for a minimum 24 hours before beginning the pressure test.
If temporary thrust blocking is needed to take immediate load, such as in making live connections, the contractor shall supply and place all bracing, blocking and/or ecology blocks as approved by the district. A Visqueen barrier shall be provided to protect fittings, bolts and other appurtenances from direct contact with the concrete.
All of the new piping, valves and blocking shall have been installed, disinfected, and tested up to the point of cutting into existing lines before the tapped or cut-in connection is made. Forty-eight-hour notice shall be given to the district in advance of any requested shut down for new connections.
(2) Bedding and Backfill. All water pipe shall be bedded with pea gravel or gravel backfill for pipe zone bedding. The pipe shall be bedded from a depth of four inches below the pipe to 12 inches above the pipe. The bedding material shall extend across the full width of the trench and shall be compacted under the haunches of the pipe.
Clay or bentonite dams shall be installed across the trench and to the full depth of the granular material in all areas of steep slopes, high groundwater, stream crossings and wetlands to prevent migration of water along the pipeline. Drainage facilities shall be installed to accommodate water buildup behind the dams in accordance with district standard details.
Backfill in roadway sections or structural areas shall be placed and compacted to a minimum of 95 percent of the modified Proctor dry maximum density per ASTM D1557 in accordance with district standard details, as well as Snohomish County, city and/or state requirements.
Backfill in unpaved easements or nonstructural areas shall be placed and compacted to a minimum of 90 percent of the modified Proctor dry maximum density per ASTM D1557. Recycled concrete is not allowed for use in district trench sections, no exceptions.
Backfill compaction shall occur in sufficiently thin lifts to achieve the density requirements specified. Copies of the compaction results shall be provided to the district prior to final acceptance.
When metallic pipes are backfilled or in contact with corrosive or cementitious material (i.e., CDF), the metallic pipe shall be wrapped using American V-Bio polyethylene encasement or equal and the pipes bedded and covered with 12 inches of clean, imported material.
(3) Valves. All valves 12 inches and smaller shall be resilient seat gate valves. All valves larger than 12 inches shall be butterfly valves.
(a) Resilient Seat Gate Valves. The gate valves shall be ductile iron body valves, iron disk completely encapsulated with polyurethane rubber and bronze, non-rising stem with “O” ring seals conforming to AWWA C509 or C515. The valves shall open counterclockwise and be furnished with two-inch square operating nuts except valves in vaults shall be furnished with handwheels. All surfaces, interior and exterior shall be fusion bonded epoxy coated, acceptable for potable water.
Gate valves shall be Clow, M&H, Kennedy, Mueller, American Flow Control, or approved equal. All valves shall be rated at a minimum of 200 psi.
(b) Butterfly Valves. Butterfly valves shall conform to AWWA C504 for flanged and C111 for MJ, Class 150B or 250B. If the district allows the use of butterfly valves based on design requirements and/or anticipated operating pressure, a flanged 250B valve may require an adaptor for the bolt pattern.
Butterfly valves shall be Pratt Groundhog Class 150B, M & H Style 4500 Class 150B or 250B, Mueller Lineseal III Class 150B or Lineseal XPII Class 250B, or approved equal.
(c) Tapping Sleeves and Tapping Valves. A stainless-steel tapping sleeve and tee shall be used for all tapped connections and manufactured by JCM Industries Model No. 432 or 462, Romac, or Smith Blair. The tapping sleeve and valve shall be tested to 100 psi prior to tapping the main.
The tapping sleeves shall be rated for a working pressure of 250 psi minimum and furnished complete with joint accessories. Tapping sleeves shall be constructed in two sections for ease of installation and shall be assembled around the main without interrupting service.
Tapping valves shall be provided with a standard mechanical joint outlet for use with ductile iron pipe and shall have oversized seat rings to permit entry of the tapping machine cutters. In all other respects, the tapping valves shall conform to the resilient seat gate valves herein specified with regards to operation and materials.
Size-on-size connections on existing cast iron pipe shall be cut-in connections only. Precautions shall be taken as directed by the district to avoid damaging existing cast iron pipe when making connections, such as not overtightening bolts.
The installation contractor for the tapping sleeves and valves shall be approved by the district.
(d) All Valves. The valves shall be set with stems vertical. The axis of the valve box shall be common with the axis projected off the valve stem. The tops of the adjustable valve boxes shall be set to the existing or established grade, whichever is applicable.
All valves with operating nuts located more than four feet below finished grade shall be equipped with extension stems to bring the operating nut to within 18 inches of the finished grade.
At the top of the extension stem, there shall be a two-inch standard operating nut, complete with a centering flange that closely fits the five-inch pipe encasement of the extension stem. The valve box shall be set in a telescoping fashion around the five-inch pipe cut to the correct length to allow future adjustment up or down. Cast iron soil pipe shall be used to extend the top valve box section to grade in deep areas.
Each valve shall be provided with an adjustable two-piece cast iron valve box of five inches minimum inside diameter. Valve boxes shall have a top section with an 18-inch minimum length. The valve boxes and covers shall be in accordance with the district standard details.
Valves located in easements or outside of paved areas shall have concrete collars with a minimum size of two-foot diameter by four inches thick.
(e) Valve Markers. Provide a four-foot-long minimum blue Carsonite valve marker post for each valve outside of asphalt. Markers shall be placed at the edge of the right-of-way opposite the valve and set so as to leave two feet of the post exposed above grade. Valve markers shall be installed and marked with the distance to valve being referenced for all valves in unpaved areas. The distance to the nearest foot to the valve shall be clearly stenciled on the side facing the valve in black numerals two inches in height.
(f) Valve Box Adjustment. Water valve covers shall be adjusted to final grade after asphalt paving is completed on new development construction. Existing water valve covers within the impacted development work area shall be replaced and upgraded to current standards in accordance with the district standard details.
(4) Fire Hydrants. Fire hydrants are required approximately every 600 feet in residential areas and/or located no more than 350 feet from the back of any proposed lot. Fire hydrants are required every 300 feet in commercial areas, or as required by the fire marshal. Distances shall be measured linearly along street or road. There shall be a minimum of three feet of clearance in all directions as measured from the operating nut of the hydrant.
Only one fire hydrant shall be installed on any dead-end water main.
New fire hydrants are not allowed on existing water mains smaller than eight-inch. The developer will be required to upgrade the existing water main to provide adequate fire flow as determined by the fire marshal.
Existing fire hydrants within the development project site area or frontage shall be upgraded to current district standards at the developer’s expense.
Hydrant pipe runs longer than 50 feet are not allowed unless otherwise approved by the district. Pipes connecting hydrants to mains shall be six inches in diameter with restrained joints. No horizontal or vertical bends are allowed in the pipe run between the main line and the hydrant. If approved, hydrant runs longer than 50 feet shall use eight-inch pipe.
All fire hydrants shall be approved by the National Board of Fire Underwriters and conform to AWWA C502, break-away type, in which the valve will remain closed if the barrel is broken. The hydrant barrel shall have a diameter of not less than seven inches, and the valve diameter shall be not less than five and one-quarter inches.
Each hydrant shall be equipped with two two-and-one-half-inch hose ports (National Standard Thread), and one four-and-one-half-inch pumper connection (National Standard Thread). The pumper port shall be oriented to be perpendicular to the primary direction of traffic flow. A permanent anodized short profile style Storz hydrant adapter and anodized Storz blind flange shall be installed on the pumper port. The size of the adapter shall as required by the local fire marshal.
Each hydrant shall be equipped with a suitable positive acting drain valve and one-and-one-quarter-inch pentagonal operating nut (counterclockwise opening).
Fire hydrants shall be Mueller Centurion, Clow Medallion, or East Jordan Watermaster 5CD250.
The holding spools between the gate valve and fire hydrant shall be made from six-inch Class 52 ductile iron pipe. The hydrant and gate valve shall be anchored in place using holding spools and mechanical joint restraint devices. Holding spools shall be one piece unless the length is in excess of 17 feet or if approved by the district. The joints shall be supplied with a mechanical joint sleeve and mechanical joint restraint device, or with Field Lok gaskets.
The fire hydrants shall be painted with two coats of yellow enamel paint in a color formula to be provided by the district. Distance to the hydrant valve shall be clearly stenciled in black numerals two inches in height on the fire hydrant below the pumper port. Align the stenciled distance on the hydrant to face the hydrant valve. The top of fire hydrant shall be painted per fire marshal requirements.
Between the time that the fire hydrant is installed and the completed facility is placed in operation, the fire hydrant shall at all times be covered in a suitable manner to clearly indicate that the fire hydrant is not in service.
(5) Blow-Offs and Air Relief Assemblies. A two-inch blowoff assembly shall be installed in a district approved location at the terminus of all dead-end water mains eight-inch diameter and smaller. Water mains greater than eight-inch diameter shall have a fire hydrant assembly installed at the terminus of dead-end mains.
A one-inch or two-inch air and vacuum release valve as required in the district standard details shall be installed at principal high points in the water system.
The installation of these items shall include connection piping, gate valve, valve box, and all accessories.
(6) Pressure Reducing Valves. If extensions require main line pressure reducing valves as determined by the district, then such entire installation, including strainers, valves, piping, vaults, and drain lines shall be installed by the developer in accordance with district standard details. The pressure reducing installation shall be a prefabricated and plumbed vault and shall include two Cla-Val globe type pressure reducing valves, sized for the area to be served downstream of the installation. [Res. 835 § 1 (Exh. 1), 2022; Res. 735 § 1, 2017.]