605Underdrains

Underdrains

605.1DESCRIPTION

1 This section describes the requirements for furnishing, installing, and backfilling underdrains.

605.2MATERIALS

1 Provide materials in accordance with the following:

Material Subsection Admixtures 801.4 Aggregate for Concrete 803 Bituminous Coated Corrugated Steel Pipe 808.5 Corrugated Aluminum-Alloy Pipe 808.6 Corrugated Steel Pipe 808.5 Curing Materials 802.1 Drainage and Filtration Geotextile 805 Fly Ash 801.2 Gravel for Drains 803 Hardware Cloth for Drains 808.4.2 Metal Delineator Posts 816.5 Plastic Pipe & Fittings 808.4 Portland Cement 801.1 Water 814.1 Wood Post 812.8

605.3EQUIPMENT

1 Ensure that equipment meets the following:

Equipment Subsection Batch Plant 513.3.1 Mixers 513.3.2 Placing Equipment 513.3.3

605.4CONSTRUCTION

605.4.1 Underdrain Selection

1 Use only the designated type and size of underdrain. If the strength class is not designated, use any strength class. Use only one type of underdrain throughout the project.

Underdrains SECTION 605 605.4.2 Pipe Installation 1 When installing underdrains along the edge of interstate highways, install under the outside shoulder unless the median shoulder is lower. 2 Excavate trenches in accordance with Subsection 206.4.1.2, Trench Excavation. Do not leave trenches open during nonworking hours unless approved by the engineer. Install drainage and filtration geotextile as specified and in accordance with Section 217, Geotextiles. 3 Install gravel backfill, perforated and nonperforated underdrain pipe, and outlets as specified. Orient perforations towards the trench bottom. In locations with a high rate of flow causing possible leakage into the embankment or subgrade to be drained, orient perforations towards the top of the trench. Use grading B gravel for drains. Cap the high point of the end of an underdrain. 605. 4.2.1 Plastic Pipe 1 Prime-coat and cement the mating surfaces of pipe and pipe fittings. Use solvent cement and primer from the same manufacturer and in accordance with the manufacturer’s recommendations. Use primer that contrasts with the color of the pipe fittings. 605.

4.3Underdrain Outlets

1 Use nonperforated outlet pipes. Daylight underdrain outlets outside of the clear zone using a concrete head wall/stilling basin, rodent screen, and outlet location post as specified. 2 Install outlet pipes on a 2 percent or steeper slope. Where the engineer determines that conditions do not allow the specified slope, install with at least a 1 percent slope. 605.

Underdrain Outlets

1 Use nonperforated outlet pipes. Daylight underdrain outlets outside of the clear zone using a concrete head wall/stilling basin, rodent screen, and outlet location post as specified. 2 Install outlet pipes on a 2 percent or steeper slope. Where the engineer determines that conditions do not allow the specified slope, install with at least a 1 percent slope. 3 Use class B concrete for head walls and stilling basins in accordance with Subsection 513.4.4, Mix Design. The engineer may approve a local commercial mix. Form, place, and cure concrete in accordance with applicable portions of Subsection 513.4, Construction. The engineer may approve the use of alternate concrete head walls and stilling basins that meet the general requirements specified.

Underdrains SECTION 605 605.4.4 Trench Backfill 1 After the engineer inspects and approves the pipe installation, backfill and compact the trench as specified and in accordance with Subsection 206.4.5, Backfilling.

605.5MEASUREMENT and PAYMENT

605.

5.1General

1 The engineer will measure:

the foot [meter] along the pipe, before backfilling. The length for payment will not exceed the length staked.

engineer will use neat lines for measurement by the cubic yard [cubic meter], with no reduction in volume for the underdrain pipe. 2 The department will pay as follows: Pay Item Pay Unit Measure to the Nearest Pay to the Nearest Gravel for Drains TON, CY [t, m

] 0.05 ton, 0.1 ft [0.05 t, 0.05 m]

0.05TON, CY

[0.05 t, m

] Underdrain Pipe (Perf) _____ in [mm] FT [m] 0.1 ft [0.05 m] FT [0.5 m] Underdrain Pipe (Non- Perf) _____in [mm] FT [m] 0.1 ft [0.05 m] FT [0.5 m] 605.

5.2Referenced Sections for Direct Payment

1 When specified, the engineer will measure Geotextile Drainage and Filtration by computing the surface area covered based on the neat lines. The department will pay in accordance with Section 217, Geotextiles.