(A) Pipe foundation shall be that portion of the trench which is 12 inches below the sewer subgrade. This portion of the trench shall be backfilled with “trench foundation” thoroughly compacted to achieve a firm, dry bed for the sewer pipe or structure. Locations of the “trench foundation” will be designated by the Engineer in the field. However, this does not relieve the contractor of the requirements of these specifications, including, but not limited to, allowable deviation of alignment and grade. Trench foundation shall be wrapped in non-woven geotextile fabric composed of polypropylene. The fabric shall be consistent with the physical characteristics of Mirafi 140N non-woven geotextile or approved equal.
(B) Trench foundation shall be three-fourths inch by one-half inch clean crushed, angular rock or Class II aggregate base. The material shall be of such size that the percentage composition by weight, as determined by laboratory sieves, will conform to the following grading:
Sieve Size | Percent Passing (By Weight) |
1-inch sieve | 100% |
3/4-inch sieve | 90 - 100% |
No. 4 sieve | 35 - 60% |
No. 30 sieve | 10 - 30% |
No. 200 sieve | 2 - 9% |
(Ord. 2019-02, passed 4-25-2019)