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Section 18 - Earthwork

Backfill to replace unsuitable materials shall be placed and compacted to a minimum

relative compaction of ninety-five percent (95%) within thirty inches (30”) of finished grade on

roadways and structural foundations. Below thirty inches (30”) of finished grade on roadways

and below subgrade in channels, compaction shall be not less than ninety percent (90%).

Suitable backfill material shall be one of the following:

1. Pit run materials as specified in Section 50-8, “Pit Run Base (Graded)”, of these

2. Roadway excavation, structural excavation, or channel excavation material approved

3. Imported borrow as specified in Section 18-6, “Imported Borrow”, in this Section of

these Specifications.

4. Cobbles as specified in Section 50-9, “Cobbles”, of these Specifications.

5. Geotextile fabric as specified in Section 50-10, “Geotextile Fabric”, of these

Specifications, and backfilled with Class 2 aggregate base.

6. Any approved combination of 1, 2, 3 and 4 above.

18-5.03 Geotextile Fabric

The need for this item is contingent upon the need to stabilize unsuitable basement material

encountered during construction and may be extended or deleted at the discretion of the

Agency. The fabric shall be as specified in Section 50-10 “Geotextile Fabric”, of these

Geotextile fabric at the overlap shall be either lapped a minimum of eighteen inches (18”) or

sewn or glued. If lapped, the fabric shall be placed so that the preceding roll overlaps the

following roll in the direction the fill material is being spread. If sewn or glued, the seam

strength shall not be less than ninety percent (90%) of the required tensile strength of the

unaged fabric. The surface to receive the fabric shall be prepared to a smooth condition free of

obstructions and debris that may damage the fabric during installation. Geotextile fabric shall

be furnished in a protective wrapping that shall protect the fabric from ultraviolet radiation and

from abrasion due to shipping and handling. The geotextile fabric shall be covered with the fill

material within two (2) Calendar Days of its placement. Should the fabric be damaged during

construction, the torn or punctured section shall be repaired by placing a piece of fabric that is

large enough to cover the damaged area and to meet the overlap requirement.

18-5.04 Approximate Quantity

Where a quantity is shown in the Contract for unsuitable material excavation, the quantity

shall be considered as approximate and is indicated for bid comparison only. No guarantee is

made or implied that the quantity shown will not be reduced or increased or deleted, as may be

required by the Agency. See Section 9-8.02, “Payment for Changes – Unit Prices”, of these

The additional excavation greater than that required for preparation of original ground or

subgrade will be paid for at the Contract unit price per cubic yard for the various types of

excavation involved. Unsuitable material excavated more than two feet (2’) below subgrade

shall be paid for as extra work as provided in Section 9, “Changes and Claims”, of these

Specifications if no item for unsuitable material excavation appears in the Contract.

Backfill, when made with material excavated from the work site, will be paid for at the same

Contract unit price paid for roadway excavation or channel excavation, whichever applies. The

pay quantity will be the same as that quantity computed for unsuitable material excavated.

Imported borrow, pit run material and cobbles, and the placing of such materials, will be paid

for as specified in these Specifications for those items.