Materials and methods. Except as noted herein, construction methods
shall conform to the State Standard Specifications for Culverts and
Underdrain and Outlets. Where high-density corrugated polyethylene
smooth interior pipe is used for storm drains, it shall be installed
in a Type II installation shown in the Standard Detail Drawings, regardless
of the internal pipe diameter, with backfill material conforming to
the State Standard Specifications Section M.08-01-21. Where reinforced
concrete pipe is used for storm drains, it shall be installed in a
Type II installation with backfill material conforming to the State
Standard Specifications Section M.02.06 (Grading A). For underdrains,
pipe shall be installed with holes in a downward position. Aggregate
used for backfilling around underdrains and slotted or perforated
pipe shall conform to the State Standard Specifications Section M.08.03-1
(No. 8 crushed stone). Sand shall not be permitted as backfill around
underdrains. Geotextile fabric, conforming to the State Standard Specification
Section M.08.01-26, shall be wrapped around the aggregate as shown
in the Standard Detail Drawings. Reinforced concrete pipe shall conform
to the State Standard Specifications Section M.08.01-6, or Section
M.08.0-10 for slotted reinforced concrete pipe. Material used for
sealing joints in concrete pipe shall conform to the State Standard
Specifications for Cold-Applied Bituminous Sealer (Section M.08.01-18),
or Pre-formed Plastic Gaskets (Section M.08.09.19). High-density corrugated
polyethylene smooth interior pipe shall conform to the AASHTO Standard
Specifications M 294 Type S, or M 294 Type SP/M 252 Type SP for perforated
high-density corrugated polyethylene smooth interior pipe.