ITEM 706 PIPE SLOPE DRAIN

Transcription

1 AFTER NOVEMBER 1, 2008 ITEM 706 PIPE SLOPE DRAIN Description. This work shall consist of the installation of temporary erosion protection and sediment control pipe slope drains, utilized during construction operations and prior to final stabilization, in accordance with these specifications and construction drawings, and as directed by the Engineer Materials. Rip-rap shall consist of 6-inch diameter stone and shall be open graded with most of the fines removed. Stone shall be composed of clean, hard, durable material free from adherent coatings, salt, alkali, dirt, clay, loam, shale, soft or flaky materials, or organic and injurious matter. Galvanized steel pipe shall be full circle pipe conforming to AASHTO Designation M245. It may be fabricated with corrugations, lap joint construction with riveted seams, or it may be fabricated with helical lock seams. Gaskets are to be O ring type meeting the requirements of ASTM C 361. Diameter to be 13/16-inch for 1/2-inch deep corrugations. Gasket lengths shall be in accordance with the pipe manufacturer's recommendations. Coupling bands shall conform to the requirements of AASHTO M36. Width of connecting bands shall be in accordance with Texas Department of Transportation's specification titled "Corrugated Metal Pipe-Coupling Bands". Dimple bands will not be accepted Construction Methods. No clearing and grubbing or rough cutting, other than as specifically directed by the Engineer to allow for soil testing, surveying and installation of erosion protection and sediment control measures, shall be permitted until sediment control and erosion protection systems are in-place. Slope drains shall be installed at the locations shown on the construction drawings, in accordance with the drawing attached to this

2 Page -2- AFTER NOVEMBER 1, 2008 specification, and as directed by the Engineer. Pipe slope drains shall be constructed in accordance with an approved schedule that clearly describes the timing during the construction process that the various erosion control measures will be implemented. Soil around and under the entrance section shall be hand-tamped in maximum 8-inch lifts, to the top of the embankment. Subgrade shall be constructed to the required elevations. All soft sections and unsuitable material shall be removed and replaced. The subgrade shall be thoroughly shaped to a smooth uniform surface. The fill material for the embankment shall be free of roots, woody vegetation, oversized stones or rocks, or organic or other objectionable matter. The area under the embankment shall be cleared, grubbed, and stripped of vegetation and root material. The inlet pipe shall have a slope of 3-percent or greater. The pipe drain diameter shall be as indicated on the construction drawings. The top of embankment over the inlet pipe and other pipes carrying water to the inlet pipe shall be at least 1-foot higher, at all points, over the top of the inlet pipe. See the attached drawing. Compaction of embankments, excavations and trenches shall be by tamping and rolling soil to a minimum of 90% of standard proctor density (ASTM Method D 698). Embankments shall be compacted in maximum 8-inch lifts. The pipe shall be secured with hold-down grommets spaced 10-feet on center. The depth of the rip-rap apron shall be equal to the diameter of the pipe drain, with 2:1 side slopes. Rip-rap shall be placed in minimum 12-inch thick layers. The Contractor shall inspect slope drains at least once every fourteen calendar days and within 24-hours of the end of a storm event of 0.5 inches rainfall or greater. The Contractor shall repair damaged slope drain sections. The Contractor shall redress the outlet as needed and replace the stone at the outlet to replace depleted stone. The Contractor shall redress and restabilize stone as needed to maintain the specified

3 Page -3- AFTER NOVEMBER 1, 2008 thickness, height, and width. The Contractor shall remove sediment from the rip-rap apron, when the sediment has accumulated to one-half the pipe diameter or one foot, whichever is less, for the pipe slope drain. All erosion protection and sediment control systems shall be maintained by the Contractor, until final stabilization. Damage caused to erosion protection and sediment control systems shall be repaired immediately. Upon removal of the pipe slope drain, the area shall be graded as per the construction drawings and stabilized with vegetation. The Contractor is responsible for removal and disposal of sediment and debris from the pipe slope drain and as directed by the Engineer. Sediment shall not be allowed to flush into the storm sewer system, waterways, jurisdictional wetlands, or onto adjacent properties. Uncontaminated sediment can be placed at the project spoil site or, if properly handled spread out to supplement fill requirements. The Engineer will designate how the sediment deposits are to be handled. Uncontaminated sediment shall not be laced in waterways or jurisdictional wetlands, unless as approved by the Engineer. If sediment has been contaminated, then it shall be disposed of in accordance with the applicable federal, state and local regulations. Off-site disposal shall be the responsibility of the Contractor. After final stabilization and at the direction of the Engineer, the Contractor, when required, shall be responsible for removing all erosion protection and sediment control systems, that are not permanent, from the project Quality Assurance. The Contractor is responsible for the control of the quality of materials incorporated into the construction and quality of completed construction. The County will engage materials engineering services to provide quality assurance testing and inspection to assist the County Engineer in determining the acceptability of materials and completed construction. Quality assurance services provided by the County do not relieve the Contractor of his responsibility for quality control. The Materials Engineer shall not have control of the means, methods, techniques, sequences or procedures of construction selected by the Contractor.

4 Page -4- AFTER NOVEMBER 1, 2008 The Materials Engineer will determine the in-place density in accordance with ASTM D 2922 or ASTM D The minimum level of testing shall be one test per 500 linear feet of embankment Measurement and Payment. When paid for separately as a pay item, measurement and payment shall be paid for at the unit price bid for each pipe slope drain, complete in place. Payment for pipe slope drain will include and be full compensation for all labor, equipment, materials, supervision and for all incidental expenses for the construction of these items, complete in-place, including but not limited to embankment and excavation, protection of trees, maintenance requirements, repair and replacement of damaged sections, removal of sediment deposits, redressing of stones, and removal of erosion protection and sediment control systems after final stabilization. There are line code(s), description(s), and unit(s) for this item. Note: This specification requires a drawing. END OF ITEM 706

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7 Page -7- AFTER NOVEMBER 1, 2008 SUMMARY SHEET ITEM PIPE SLOPE DRAIN Other Specifications Required: Item 725, General Source Controls Reference Standards: AASHTO M 245 ASTM C 361 AASHTO M 36 Description: Describes the method for constructing pipe slope drains. Payment: If paid for separately, paid for by each unit of pipe slope drain. DO NOT INCLUDE THIS SHEET IN CONTRACT SPECIFICATIONS.