4143.01 DESCRIPTION.
Subdrain pipe shall be of the size and type shown in the contract documents. When not designated, subdrain pipe shall meet the following requirements:

A. Pipe for Horizontal Drains.
Horizontal drains shall be plastic pipe conforming to requirements of ASTM D 1785, Schedule 80. Unless otherwise specified, the pipe shall have 3 rows of slots, 0.010 inch ± 0.005 inch (254 µm ± 127 µm) wide, on 120 degree centers around the circumference. The pipe shall have a minimum of 0.75 square inch (1588 mm²) of slot opening per linear foot (meter), and shall be provided with a suitable cap at the inlet end. Caps and couplings shall be subject to approval of the Engineer.

B. Pipe for Longitudinal Subdrains.
Perforated corrugated polyethylene (PE) tubing and fittings shall be used as subdrains and shall be manufactured and marked in accordance with AASHTO M 252 with the following modification:

The tubing shall be perforated with slots in accordance with AASHTO M 252. Circular perforations will not be approved.

Subdrain outlets shall be one of the following options:

1. Corrugated metal pipe meeting the requirements of Article 4141.01, including tapered ends, when required.
2. Corrugated Polyethylene (PE) pipe, type S, approved per Materials I.M. 443 Appendix A, Part B.
3. Corrugated Polyvinyl Chloride (PVC) pipe, Type S, approved per Materials I.M. 443 Appendix A, Part C.

When special connections are required for subdrain outlets, they will be detailed in the contract documents

The outlet covering shall be a rodent guard meeting the requirements of Materials I.M. 443.01. It shall be attached as shown in the contract documents. Inspection and acceptance will be in accordance with Materials I.M. 443.01.

C. Standard Subdrains
Standard subdrains shall meet the requirements of AASHTO M 196/M 196M or M 36/M 36M Type I or Type III, or shall be drain tile Section 4148 or Plastic Pipe (Section 4146) or shall be polyethylene tubing meeting the requirements of Article 4143.01, B. Underdrains furnished according to AASHTO M 36/M 36M shall have a specified sheet thickness of 0.052 inch (1.32 mm) for 6 inch (150 mm) diameter and 0.064 inch (1.63 mm) for larger diameters. Underdrains furnished according to AASHTO M 196/M 196M shall have a specified sheet thickness of 0.048 inch (1.22 mm) for 6 inches (150 mm) diameter and 0.060 inch (1.52 mm) for larger diameters. Subdrains shall be perforated only when specified. As an option, AASHTO M 36/M 36M subdrains may be perforated with slots formed on the outside crests of helical corrugations, approximately 1 inch (25 mm) in length and 0.1 inch (2.5 mm) in width, spaced at 2 inches (50 mm) on centers.

When corrugated steel subdrains are specified, coated subdrains may also be specified, and the coating shall be in accordance with Article 4141.02.

Plastic pipe meeting requirements of ASTM F 758, D 3034, or D 2751 shall have perforations as specified in ASTM F 758. Plastic pipe meeting requirements of ASTM F 949 with slots may also be used.

When embedded in granular or porous backfill material, the subdrain shall be slotted plastic pipe meeting the requirements of ASTM F 949 or perforated, corrugated polyethylene (PE) tubing meeting the requirements of Article 4143.01, B.