Chapter 7.20
CONSTRUCTION MATERIALS

Sections:

7.20.010    General.

7.20.020    Sewer pipe.

7.20.030    Manholes.

7.20.040    Frame and covers.

7.20.010 General.

The type and class of materials to be used shall be as shown on the project plans approved by the district. Where no specific reference is shown, the following specifications shall govern the materials used. All materials shall be new and undamaged of a known brand, with replacement parts readily available from the general Seattle area.

Prior to the installation of any of the facilities required on the project, all materials shall be approved by the district.

All reference specifications herein shall be of the latest revision. [Res. 2015-6-1.]

7.20.020 Sewer pipe.

Sewer pipe material shall be of the following type unless otherwise specified or directed:

Locations with less than four (4) feet of cover from finished grade

Class 52 Ductile Iron Pipe

Locations with between four (4) feet and eighteen (18) feet of cover from finished grade

PVC Pipe, ASTM 3034

Locations with more than eighteen (18) feet of cover from finished grade

Class 52 Ductile Iron Pipe, or PVC C900 Pipe

Where directed

High Density Polyethylene (HDPE) Pipe

(1) PVC Pipe and Fittings – ASTM 3034. Pipe and fittings shall be integral wall bell and spigot, rubber gasket joint, unplasticized polyvinyl chloride (PVC) pipe. All PVC pipe shall have a minimum “pipe stiffness” of 46 at five percent deflection and 73 degrees Fahrenheit when tested in accordance with ASTM Designation D 2412, external loading properties of plastic pipe; and a minimum impact strength of 210 feet-pounds based on ASTM D 3034 at 73 degrees Fahrenheit using a 20 pound Tup A.

All ASTM 3034 PVC sewer pipe and fittings manufacture and installation shall conform with ASTM recommended specifications D 3034, current revisions, and all installation shall be in strict compliance with the manufacturer’s directions. All pipe shall be clearly marked with the date of manufacture. There shall be no reduction in pipe wall thickness at the bell as a result of bell formation. All pipe shall be provided with a reference mark for proper spigot insertion. Joint gaskets shall be fabricated from a compound of which the basic polymer shall be a synthetic rubber consisting of styrene, butadiene, poly-isoprene, or any combination thereof and shall meet the requirements of ASTM 1869, latest revisions.

(2) Class 52 Ductile Iron Pipe and Fittings. Class 52 ductile iron pipe shall be new, cement-lined, conforming to ANSI Standard A21.51 (AWWA C-151).

Ductile iron pipe shall be push-on joint or mechanical joint. Pipe with push-on joints shall be furnished with a single rubber ring gasket. All gaskets, including M.J., shall be lubricated to affect the seal. Pipe with mechanical joints shall be furnished with a mechanical joint of the stuffing box type, including rubber gasket, cast-iron gland, and tee-head bolts and nuts to affect the seal. All joints shall conform to ANSI Standard A21.11 (AWWA C-111).

Internally locked joint shall be in accordance with ANSI A21.11 and equal to U.S. Pipe TR Flex, U.S. Pipe Field Lok, or Griffin “Snap Lok.”

Bell and socket joints shall be in accordance with ANSI A21.10 and equal to U.S. Pipe “Usiflex.”

Standard thickness cement mortar lining shall be in accordance with ANSI Standard A21.4 (AWWA C-104).

Ductile iron pipe shall be encased in polyethylene encasement. Material and installation shall be in accordance with AWWA C105. Installation shall be in accordance with Method A or Method C.

The contractor shall furnish certification from the manufacturer of the pipe and gasket being supplied that the inspection and all of the specified tests have been made and the results thereof comply with the requirements of this standard.

(3) PVC Pipe and Fittings – AWWA C900. All AWWA C900 PVC pipe and fittings manufacture and installation shall conform with AWWA recommended specifications C900, current revisions, and all installation shall be in strict compliance with the manufacturer’s directions. Pipe and fittings shall be integral wall bell and spigot, gasketed pipe, extruded from virgin PVC compounds with cell classification 12454 B or better, as defined in ASTM D1784. Gaskets shall be elastomeric meeting requirements of ASTM F477. Fittings shall be in accordance with AWWA C907. PVC C900 pipe shall have a minimum pressure class rating of 100 (DR25) with cast iron pipe outside diameter conforming to ASTM D2122.

(4) Tees and Wyes. Connections for side sewer stubs shall be six-inch inside diameter tee fittings fabricated in the manufacturer’s plant. Wye branches shall be used where the sewer main size is less than eight-inch inside diameter. No field cut-in tees or wyes will be allowed under these specifications without written approval of the district.

(5) High Density Polyethylene (HDPE) Pipe and Fittings. The material shall comply with the requirements for Type III C5 P34 as tabulated in ASTM D 1248 and have PPI recommended designation of PE 4710 SDR-17 (125 psi). A melt flow (condition F) of less than 5.0 grams per 10 minutes shall be required as determined by ASTM D 1238-65T and exceed 5,000 hours of environmental stress crack resistance with no failure and no indication of stress crack initiation as determined by ASTM D 1693, Condition C.

The workmanship shall be of the highest level compatible with current commercial practice. The PE pipe shall be homogeneous throughout and free of visible cracks, holes, foreign inclusions, or other injurious defects. It shall be uniform in color, opacity, density and other physical properties.

The pipe shall be non-pressure rated. Butt fusion of pipes and fittings shall be performed in accordance with the pipe manufacturer’s recommendations as to equipment and technique. The pipe shall be fused by an individual who has a demonstrated ability to fuse polyethylene pipe in the manner recommended by the pipe supplier and/or the fusion manufacturer.

In direct burial applications, the trench and trench bottom, embedment materials and bedding installation practices shall be as specified in ASTM 2321, Sections 6, 7, 8, and 9. The pipe shall be Phillips 66 Driscopipe 1000 or equal.

Provide special anchor block at each end of the HDPE section as noted on the construction drawing and detailed in the sewer standard detail. [Res. 2015-6-1.]

7.20.030 Manholes.

Manholes shall be of the offset type and shall be precast concrete sections with either a cast in place base or a precast base made from a 3,000 psi structural concrete. Joints between precast wall sections shall be confined O ring. They shall be constructed in full compliance with the details shown on Standard Sewer Detail 1, Precast Manhole, and as further specified herein.

(1) Manhole Sections. Manhole sections shall be placed and aligned so as to provide vertical sides and vertical alignment of the ladder steps. The ladder shall be rigidly attached to the side of the manhole. The completed manhole shall be rigid, true to dimension, and be watertight. Rough, uneven surfaces will not be permitted.

Masonry units (manhole adjusting brick) shall conform to ASTM C 32, Grade MM. The outside and inside of manhole adjusting bricks and the joints of precast concrete sections shall be plastered and troweled smooth with one-half inch (minimum) of mortar in order to attain a watertight surface.

The mortar used between the joints in the precast sections and for laying manhole adjusting bricks shall be composed of one part cement to two parts plaster sand. All joints shall be thoroughly wetted and completely filled with mortar, smoothed both inside and out to ensure watertightness.

(2) Manhole Steps. Manhole steps shall be made of copolymer polypropylene plastic coated one-half-inch Grade 60 steel reinforcing bars, M.A. Industries PS2-PF manhole step or equal. See the standard detail for the special step in adjusting ring area.

(3) Grade Adjustment. Manhole necks that are not less than 14 inches nor more than 26 inches shall be provided between the top of the cone or slab, and the top of the manhole frame.

(4) Channels. Channels shall be made to conform accurately to the sewer grade and shall be brought together smoothly, with well-rounded junctions, satisfactory to the district engineer.

The channels shall be field poured after the inlet and outlet pipes have been laid and firmly grouted into place at the proper elevation. Precast may be allowed if preapproved by the district engineer. Allowances shall be made for a minimum of one-tenth foot drop in elevation across the manhole in the direction of flow. The maximum allowable drop in inlet elevation across the manhole in the direction of flow shall be one foot. Channel sides shall be carried up vertically from the invert to three-quarters of the diameter of the various pipes. The concrete shelf shall be warped evenly and sloped two percent to drain. Rough, uneven surfaces will not be permitted. Channels shall be constructed to allow the installation and use of a mechanical plug of the appropriate size in the incoming and outgoing pipes.

(5) Pipe Connections. All rigid pipe entering or leaving the manhole shall be provided with flexible joints within 12 inches of the manhole structure and shall be placed on firmly compacted bedding. Special care shall be taken to see that the openings through which pipes enter the structure are completely and firmly filled with mortar from the outside to ensure watertightness. All PVC pipe connections to manholes shall be made with GPK PVC manhole adapters (also known as “sand collars”) with an external abrasive silica layer or approved Kor ‘n Seal boots.

All stubbed out sewer pipes placed through manhole walls for future connections shall be suitably plugged and blocked in a manner acceptable to the district.

(6) Drop Manholes. If preapproved by the district engineer, drop manholes shall, in all respects, be constructed as a standard manhole with the exception of the outside drop connection, as shown on Standard Sewer Detail 3, Drop Manhole.

(7) Lift Holes and Steel Loops. All lift holes shall be completely filled with expanding mortar, smoothed both inside and out, to ensure watertightness. All steel loops must be removed flush with the manhole wall. The stubs shall be covered with mortar and smoothed. Rough, uneven surfaces will not be permitted.

(8) Heat Shrinkable Wraparound Sleeves. All manholes shall be installed with heat shrinkable wraparound sleeves from the manhole ring flange to below the adjustment rings and blocks. Heat shrinkable wraparound sleeves shall be “Wrapid Seal” as manufactured by Canusa, or approved equal. [Res. 2015-6-1.]

7.20.040 Frame and covers.

Frames and covers shall be cast iron and conform to Standard Sewer Details 6, 7, and 8, Manhole Frame and Cover, equal to Olympic Foundry Part No. MH30, modified to have one each seven-eighths-inch diameter lift hole, and Standard Sewer Detail 9, Locking Cleanout, equal to Olympic Foundry Part No. M1025. Castings shall conform to the requirements of ASTM A 48, Class 30, and shall be free of porosity, shrink cavities, cold shuts or cracks, or any surface defects which would impair serviceability. Repair of defects by welding, or by the use of smooth-on or similar material, will not be permitted. Frames and covers shall be machine-finished or ground-on seating surfaces so as to assure non-rocking fit in any position and interchangeability of covers. When required, frames and covers shall be provided with locking lids as shown on Standard Sewer Detail 7, Locking Manhole Frame and Cover, equal to Olympic Foundry part no. MH30D/T modified to have one each seven-eighths-inch diameter lift hole. Locking lids will be required, except when manholes are located in paved rights-of-way, unless otherwise directed by the district. Rings and covers shall be adjusted to conform to the final finished surface grade of the street and to the satisfaction of the district. [Res. 2015-6-1.]