the No. 200 sieve; no stone greater than two-third (2/3) loose lift thickness, or
six inches, whichever is smaller.
2. Select Backfill:
Select backfill shall be granular, well graded friable soil, free of rubbish, ice,
snow, tree stumps, roots, clay and organic matter, and other deleterious or
organic material; graded within the following limits:
Sieve Size Percent Finer by Weight
3” 100
No. 10 30 - 95
No. 40 10-70
No. 200 0-10
H. SPECIAL PIPE BEDDING MATERIAL
1. The special pipe bedding material shall consist of a filter cloth installed on the
trench bottom before backfilling with crushed stone as specified and as shown on
the contract drawings.
2. The filter cloth shall be composed of needle punch, stapled fibers thermally
bonded together to form a sheet.
3. The filter cloths shall possess the following minimum properties:
Grab strength: 1201bs ASTMD4632.
Elongation: 50% ASTM D 4632
Burst Strength: 240 psi ASTM D 3786
Puncture Strength: 65 Ibs. ASTM D 4833
Trapezoid Tear: 4 0 Ibs. ASTM D 4533
Equivalent opening size: No. 70 sieve ASTM D 4751
Permittivity (sec"') 1.8 ASTM D 4491
Flow Rate (gal/min/ft’) 135 ASTMD-4491
4. The filter cloth shall be Mirafi 140N by Muirafi, Inc. Charlotte, NC; Foss-65 by
Foss Manufacturing Co., Haverhill, MA; Supac 4NP, Phillips Fibers Corp.,
Greenville, SC or approved equal.
I, CRUSHED GRAVEL:
1. Crushed gravel shall consist of inert material that is hard, durable stone and
coarse sand, free from loam and clay, surface coatings and deleterious materials.
The coarse aggregate shall have a percentage of wear, by the Los Angeles
Abrasion Test, of not more than 50.
02300-4
