Excavation CS_255.doc

Construction Specification 255 — Excavation

1.

Scope

The work shall consist of the excavation required by the drawings and specifications and disposal of the excavated materials.

2.

Use of excavated material

To the extent they are needed, all suitable material from the specified excavations shall be used in the construction of required permanent earthfill or rockfill. The suitability of material for specific purposes is determined by the engineer. The contractor shall not waste or otherwise dispose of suitable excavated material.

3.

Disposal of waste materials

All surplus or unsuitable excavated materials are designated as waste and shall be disposed of at the locations shown on the drawings.

4.

Borrow excavation

When the quantities of suitable material obtained from specified excavations are insufficient to construct the specified earthfill structures and earth backfill, additional material shall be obtained from contractor supplied borrow areas.

5.

Overexcavation

Excavation in earth beyond the specified lines and grades shall be corrected by filling the resulting voids with approved, compacted earthfill. The exception to this is that if the earth is to become the subgrade for riprap, rockfill, sand or gravel bedding, or drainfill, the voids may be filled with material conforming to the specifications for the riprap, rockfill, bedding, or drainfill. Before correcting an overexcavation condition, the contractor shall review the planned corrective action with the engineer and obtain approval of the corrective measures.

6.

Measurement Compensation for any item of work described in the contract, but not listed in the bid schedule is included in the payment for the item of work to which it is made subsidiary. Compensation for such items is identified in section 8 of this specification.

7. Items of work and construction details

All excavations shall be constructed to the lines and grades shown on the drawings or as directed by the engineer or his representative.

Items of work to be performed in conformance with this specification and the construction details therefor are:

a.

Subsidiary Item - Excavation, Outlet Channel (1) This item shall consist of the excavation required for the removal of debris from the outlet channel. The channel shall be shaped to the approximate cross sections and grades shown on the drawings or as staked in the field.

(2) Excavated materials unsuitable for direct placement as earthfill shall be placed in the waste areas as directed by the engineer.

(3) The surfaces of waste areas shall be left in a neat and sightly condition and sloped to provide drainage. Compaction of waste materials shall not be required.

(4) The volume of Excavation, Outlet Channel will not be measured and no separate payment will be made for this item. Compensation for Excavation, Outlet Channel, will be included in the payment for Earthfill.

b.

Subsidiary Item - Excavation, Borrow (1) This item shall consist of the excavation in the designated borrow area for obtaining fill materials needed for construction of the permanent fill. Additional borrow areas, if needed, will require approval of the engineer prior to using the material as earthfill.

(2) All surface materials suitable for topsoil shall be stripped from the borrow areas and placed in designated locations.

(3) The surface of the finished borrow area adjacent to the outlet channel outside of the auxiliary spillway channel shall be uniformly graded to drain to the outlet channel. The slopes and bottom of the borrow area shall be smoothed as needed to allow for seeding of the area.

(4) The volume of Excavation, Borrow will not be measured and no separate payment will be made for this item. Compensation for Excavation, Borrow, will be included in the payment for Earthfill.

NRCS – March 2009

255-1 KS –Big Caney Watershed District EWP, FRD 12