605Subsurface Drains

Subsurface Drains

Description

605.01This work consists of constructing underdrains, edge drains, geocomposite drains, and

french drains, per these specifications and in conformity with the lines and grades shown on the plans or established.

Materials

605.02Materials shall meet the requirements specified in the following subsections:

Corrugated Steel Pipe 707.04 Bituminous Coated Corrugated Steel Pipe 707.05 Drain Tile 706.04 Vitrified Clay Pipe 706.06 Corrugated Aluminum Pipe 707.07 Plastic Pipe 712.11 Gaskets 705.03 Filter Material 703.09 Geotextiles 712.08 Geocomposite Drains 712.12

Pipe for subsurface drains shall be any type of pipe material listed above. When corrosion resistant pipe is specified on the plans, the materials shall conform to the requirements of

Subsurface drain outlet pipe may be perforated or nonperforated, and shall meet the requirements specified in subsections 707.04, 707.05, 707.07, or 712.11.

Construction Requirements

605.03Pipe Underdrain and Pipe Edge Drain. The trench shall be excavated to the

dimensions and grade shown on the plans. Sufficient Geotextile (Drainage) (Class 3) shall be placed along the bottom and sides of the trench as shown on the plans to provide the required overlap over the top of the filter material. Filter material of the class designated on the plans shall be placed in the bottom of the trench for its full width and length. Perforated pipe shall be placed with the perforations down and the pipe sections shall be joined securely with the appropriate coupling fittings or bands. Joining shall conform to the applicable requirements of subsection 603.07 except as noted above.

After the pipe installation has been inspected and approved, the designated filter material shall be placed to a height of 12 inches above the top of pipe. Care shall be taken not to displace the pipe or the covering at open joints. The remainder of the filter material shall then be placed to the required height, the drainage geotextile folded over the top of the filter material, and the remainder of the trench backfilled.

605.04

605.04Geocomposite Drains. The geocomposite drain for subsurface drainage behind a

retaining wall shall be placed along the full length of the wall. It shall be attached to the wall with an approved adhesive or per the manufacturer's recommendations. The trench for geocomposite underdrain and geo-composite edge drain, for subsurface drainage at pavement edge and elsewhere as specified on the plans, shall be excavated to the dimensions and grade shown on the plans. The geocomposite drain material shall then be placed along the downhill side, or the pavement side, of the trench and secured to the trench side.

Backfill shall be placed to avoid damage to the geocomposite drain material.

605.05French Drain. The trench for French drain shall be excavated to the width and

depth shown on the plans. The trench shall be lined with Geotextile (Drainage) (Class 3) and filled with the designated filter material to the depth shown on the plans. The drainage geotextile shall be folded over the top of the filter material. Any remaining unfilled upper portion of trench shall be backfilled with embankment material.

605.06Subsurface Drain Outlet. The trench for subsurface drain outlet shall be excavated

to the width and depth necessary to place the pipe on a drainable grade, as shown on the plans or as directed. Pipe shall be laid in the trench with all ends joined securely with the appropriate couplings, fittings or bands. After inspection and approval of the pipe installation, the trench shall be backfilled and compacted per subsection 206.03. Where the outlet pipe ends on a slope or ditch, it shall be constructed with an erosion control pad, and an animal guard. The location shall be marked with a delineator post that conforms to Section 612. The animal guard screen shall be held securely in place with a coupling or fastening band or by another approved method.

Method of Measurement

605.07Pipe underdrain and pipe edge drain will be measured by the linear foot of pipe of

the size specified placed and accepted. French drain will be measured by the linear foot of trench excavated and filled with filter material and accepted. Geocomposite underdrain and geocomposite edge drain will be measured by the linear foot along the base of the geocomposite drain material for the full length installed and accepted. Geocomposite drain both with and without pipe will be measured by the square yard of geocomposite drain material placed on the vertical wall surface and accepted. Subsurface drain outlet will be measured by the linear foot of pipe placed and accepted from the end of a subsurface drain to the discharge end of the outlet pipe.

Basis of Payment

605.08The accepted quantities of subsurface drains will be paid for at the contract unit

price for each of the pay items listed below that appear in the bid schedule.

605.08

Payment will be made under:

Pay Item Pay Unit ___Inch Perforated Pipe Underdrain Linear Foot French Drain Linear Foot Geocomposite Underdrain Linear Foot Geocomposite Drain without Pipe Square Yard Geocomposite Drain with Pipe Square Yard Geocomposite Edge Drain Linear Foot Pipe Edge Drain Linear Foot Subsurface Drain Outlet Linear Foot

Payment shall be full compensation for all work and materials required to complete the item including drainage geotextile, drainage core, securing devices, adhesives, sewn seams, pipe, filter material, excavation, and backfill. Payment for subsurface drain outlet shall include the erosion control pad, the animal guard, and the delineator post.

605.08

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606.01