(A) Fill materials.
(1) Granular backfill material shall be as defined in § 211.02 (“B” Borrow) of the state’s Department of Highways Standard Specifications, latest edition. Maximum stone size shall not exceed one inch or the maximum size recommended by the pipe manufacturer, whichever is smaller.
(2) Coarse aggregate shall be No. 1 or No. 2 size coarse aggregate as specified by § 904.82 of the state’s Department of Highways Standard Specifications, latest edition.
(B) General fill. General fill material shall consist of natural soils such as clays, sands, and silts found in place, subject to the approval of the Engineer. Natural materials containing organics, gravels and large rocks shall not be used for general fill unless specifically approved by the Engineer.
(C) Structural backfill. Structural backfill material shall be the same as granular backfill as specified above.
(D) Porous backfill. Porous backfill material shall consist of gravel, or crushed stone meeting the requirements of ASTM 448, No. 4 size coarse aggregate.
(2004 Code, Art. I, § A, part 2)