§ 15.01.570. PVC plastic pipe.

This section covers the requirements for rigid polyvinyl chloride pipe and fittings, hereinafter called PVC pipe and PVC fittings. The pipe and fittings and installation in sanitary sewer, storm drain and other gravity line construction, shall meet or exceed all of the requirement ASTM Specification D-3034 Type PSM for SDR 35 pipe for diameters from four inches to fifteen inches and ASTM F679 for eighteen inches to twenty-four inches with integral bell gasket joints, and be supplied in maximum twenty-foot lengths. This pipe shall be homogeneous throughout and free from cracks, holes, foreign inclusions or other defects. The pipe shall be as uniform as commercially practical in color.

All PVC sewer pipe shall be made from clean, virgin, Type 1, Grade 1, PVC conforming to ASTM resin specification D-1784. All pipe joints shall be bell and spigot type with rubber ring gasket conforming to ASTM D-1869, to permit expansion and contraction. Pipe and fittings must be assembled with nontoxic lubricant. Four-inch and six-inch diameter pipe may be the solvent weld type provided an expansion joint is provided if the length of run exceeds one hundred lineal feet. All pipes shall be less than twenty feet in length.

Spigot ends will have fifteen degree tapered ends with memory mark around the diameter of the pipe to indicate proper insertion depth.

Wyes shall be of the same material as the pipe, and in no case shall have thinner walls than that of the pipe furnished. Sample wyes must be submitted for the city engineer's approval, and his approval must be obtained before purchase of the wyes.

For hydraulic design considerations, a Mannings n value of 0.012 for storm drain and 0.013 for sewer shall be used.

1.

PVC fittings. Fittings shall be made of PVC plastic conforming to ASTM-D1784, have a cell classification as outlined in ASTM D-3034.

2.

PVC pipe installation. Pipe installation shall be in accordance with ASTM Recommended Practice D-2321 and the manufacturer's requirements. All pipe installation shall proceed upgrade on a stable foundation, with joints closely and accurately fitted.

PVC pipe is a flexible pipe and requires deflection testing as per Section 15.01.630.

Pipe shall be installed with uniform bearing under the full length of the barrel, with suitable excavations being made to receive pipe joints

Select material shall be compacted around the pipe to firmly bed the pipe in position. Haunching material (bed to springline) should be carefully worked under the haunches by hand as per ASTM D2321. The bedding shall be compacted from the pipe to the trench wall to ensure support. If adjustment of position of a pipe length is required after being laid, it shall be removed and re-jointed as for a new pipe. When laying is not in progress, the ends of the pipe shall be closed with a tight-fitting stopper to prevent the entrance of foreign material.

As per ASTM D2321, trench box installations will require a subtrench below the trench box or a trench box will not be allowed. Subtrenchs can not be deeper than twenty-four inches by OSHA Standards. Therefore, pipe diameters in excess of twenty-four inches will need to be installed without a trench box and with side slopes laid back to meet OSHA requirements. It is the contractors responsibility to follow OSHA guidelines for safe practices.

In addition to the above requirements, all pipe installation shall rigidly adhere to the specific requirements of the pipe manufacturer.

Where pipe product is provided with a joint system intended to allow for segmental installation of piping materials, joints shall be closed tightly such that gasket system is fully engaged and no more than one-half inch of gap section between overlapping joint material (bell and spigot or another approved method) is visible via a televised inspection methods. Contractor shall meet with city designated inspection representative prior any construction commencing to review city standards relative to installation of piping system.

3.

PVC pipe construction loads. To preclude damage to the pipe and disturbance to the embedment zone, a minimum depth of backfill should be maintained before allowing vehicles or heavy construction equipment to traverse the pipe trench.

The minimum depth of cover should be established by the project engineer based on the specific project requirements.

In the absence of such a detailed investigation, the installer shall meet the following minimum cover requirements before allowing vehicles or construction equipment to traffic the trench surface, assuming that the minimum embedment zone densities are prepared as per ASTM D2321:

Provide minimum cover of at least twenty-four inches or one pipe diameter (whichever is larger) where Class I embedment materials have been utilized, or provide minimum cover of at least thirty-six inches or one pipe diameter (whichever is larger) where Class II or lower embedment materials have been utilized, and allow at least forty-eight inches of cover before using a hydrohammer for compaction directly over the pipe. Where construction loads may be excessive (e.g. cranes, earth moving equipment, etc.) consult with the project engineer to determine minimum operating cover requirements.

4.

Gravel foundation for PVC pipe. The pipe foundation shall be a minimum of four inches in the compacted condition. Wherever the subgrade material does not afford a sufficiently solid foundation to support the pipe and superimposed load, it shall be excavated to such depth as may be necessary and replaced with crushed rock or gravel compacted into place. Gravel foundation material for pipe shall be placed only when, and to the depth, requested by the engineer or specified on the drawings.

Gravel for PVC pipe foundations shall be clean crushed rock or gravel with one hundred percent passing a one-and-one-half-inch screen and maximum of five percent passing a three-fourths-inch sieve.

5.

PVC pipe embedment. All pipe shall be protected from lateral displacement and possible damage resulting from impact or unbalanced loading during backfilling operations by being adequately bedded in suitable embedment material. The bottom of the trench shall be of stable materials. In general, coarse-grained soils, free of rocks and stones, such as graded crushed rock, gravel, sand, and other granular materials, are considered stable materials. A stable material shall be placed and compacted under the pipe haunches and up to the spring-line in uniform layers not exceeding eight inches in depth. When bedding is required, the same material should be used for both bedding and haunching. The same material shall be used to backfill the trench from the springline of the pipe to a point at least twelve inches above the top of the pipe. Each eight-inch layer of bedding, haunching and initial backfill shall be placed, then carefully and uniformly compacted to ninety-five percent of AASHTO T-180 (ASTM D-1557) density. Extra-fine sand, clay, silt, or large soil lumps shall not be allowed as bedding, haunching or initial backfill material.

The remaining backfill over the top of the initial backfill shall be placed in accordance with Section 15.01.430.

Modified bedding material shall be graded as follows: one hundred percent passing a one-and-one-half inch screen and five percent passing a No. 4 sieve.

(Ord. No. 2007-07-31, §§ 6.6—6.6.5, 7-10-2007; Ord. No. 2010-11-24, § 2, 11-23-2010; Ord. No. 2011-06-17, § 1, 6-28-2011)