023180 - Excavation and Backfill.pdf

Telecommunications and Wiring Specifications 02 3180 AG-05G1-S-11-0021

Newport Ranger District, Colville National Forest 1

Rev. Date 12/01 Telecommunications and Wiring 02318 - 1/12

Excavation & Backfill for Utilities

SECTION 02 3180

EXCAVATION AND BACKFILL FOR UTILITIES

1. PART 1 - GENERAL

1.01 SUMMARY

A. This section specifies excavation and backfill for utilities, including excavation;

furnishing, hauling and placing of backfill material; disposal of excess or unsuitable backfill material; and grading.

B. The disposal site is as designated by the Contracting Officer.

C. Class of Material.

1. Material to be excavated for installation of utilities is unclassified.

1.02 SUBMITTALS

A. Excavation.

1. Notify Contracting Officer when excavation is completed. Do not place pipe, cable or bedding backfill until the excavation is approved by the Contracting

Officer.

B. The Contractor shall provide submittals:

1. Certification, test results, source and samples for all imported material.

2. Required permits.

1.03 PROJECT CONDITIONS

A. The materials investigation data shown on the Drawings is from Government conducted investigations, and is provided as information only. This information is subject to interpretation and should be considered as representative of the material only at the specific materials investigation test sites.

B. Contractor shall be responsible to call for utility locate services, if available in area.

2. PART 2 - PRODUCTS

2.01 MATERIALS

A. Backfill Materials.

1. Backfill material shall contain no frozen or organic material.

a. Asphalt Surfaces.

1) Washington Department of Transportation (WSDOT), Class "B" or

"F.”

2. Crushed Rock.

a. Crushed aggregate, meeting the requirements of AASHTO M147 grading

3. Electrical Bedding Material.

a. Natural sand passing the #8 sieve, without sharp chips or points.

4. Select Material.

a. Fine soil or sand, 100 percent passing the #4 sieve.

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5. Select Excavated Material.

a. Excavated material containing no rocks larger than 6 inches in largest dimension.

6. Topsoil.

a. Soil or loam containing no rock larger than 2 inches.

b. Loose, nonplastic soil free of roots, weeds, subsoil admixture, excessive organic matter, clods, stones, gravel or other material detrimental to plant growth. Maximum particle size 1/2 inch.

3. PART 3 - EXECUTION

3.01 CONSTRUCTION

A. Excavation.

1. Excavation shall not begin until all clearing and grubbing work is completed except for final debris disposal. Operations shall be in compliance with the requirements and restrictions of OSHA, and the Washington Occupational

Safety and Health Code.

2. All trenches shall be excavated in reasonably close conformity with the lines and grades shown on the Drawings. Any shifting or change from the alignment and grade shown on the Drawings must receive prior approval by the Contracting Officer in writing.

3. Lay utilities in continuous open trench. Short tunnel sections or boring may be used in special locations with the approval of the Contracting Officer.

4. Trim roots flush with trench wall.

B. Overexcavation.

1. Restore to grade any overexcavation by backfilling with select material.

C. Salvage of Topsoil.

1. Excavate top 6 inches of surface material and stockpile separately for use as topsoil backfill material.

2. Suitable topsoil not containing well-bound pieces of sod may be conserved for use as topsoil backfill material.

D. Wet Excavation.

1. If water is encountered during trench excavation, provide adequate pumping equipment and piping to keep trench free from water and dispose of the water without damage to adjacent property. Separate payment will not be made for pumping of water from trenches or for excavation of material rendered unsuitable as a result of water encountered.

E. Unsuitable Material.

1. Where unsuitable material is encountered in the trench bottom, as determined by the Contracting Officer, excavate the trench below grade to the depth specified by the Contracting Officer.

F. Excavated Material.

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1. Pile excavated material at the side of the trench where it will give the best protection for the work. Leave adequate space between the toe of the spoil pile and edge of trench to prevent material from falling into the trench.

G. Backfill.

1. Do not place backfill until installation of pipe or cable has been approved by the Contracting Officer.

2. Before compacting backfill other than rock or sand, prepare material to a water content that will permit proper compaction by either aerating the material if it is too wet, or spraying the material with water if it is too dry. Thoroughly mix each lift before compaction to assure uniform distribution of water content. Do not compact material above pipe or cable until there are 6 inches of cover over the pipe or cable.

3. Compact each lift (with the required number of passes of a mechanical vibrating tamper over the entire layer) (to the required density).

a. Select Material.

1) Place in lifts 6 inch or less and compact to a density of not less than

95 percent of the maximum density determined by AASHTO T99.

b. Select Material.

1) Place in 6 inches lifts or less and compact with a minimum of 3 passes over the entire lift surface.

c. Bedding Material.

1) Place in lifts 4 inches or less in thickness and compact with a minimum of 3 passes over the entire lift surface. Compact around pipe barrel and bells by hand tamping.

d. Select Excavated Material.

1) Distribute large rocks so they are individually surrounded by fine materials. Place select excavated material as follows where backfill classes are indicated on Drawings.

a) Class A: Place in 24 inch lifts or less to within 8 inches of finished grade and compact each lift with 3 passes of tamper. On pipe gradients over 30 percent (0.3 foot/foot) place in 12 inch horizontal lifts and compact each lift with 3 passes of tamper.

b) Class A: Place in 12 inch lifts or less to within 8 inches of finished grade and compact to at least 90 percent of the maximum dry density as determined by AASHTO T99.

c) Class D: Place in l2 inch lifts or less and compact each lift with 6 passes of tamper. At depths greater than 5 feet, compact each lift with 3 passes of tamper.

d) Class D: Place in 12 inch lifts or less. Compact each lift to at least 95 percent of the maximum dry density as determined by

AASHTO T99.

e. The number of tamper passes required may be reduced upon acceptance by the Contracting Officer, if approved test method results demonstrate that the backfill compaction meets or exceeds the density of the natural

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Contractor's expense.

4. Water compaction shall not be used.

3.02 REPAIR/RESTORATION

A. Damage to existing underground utilities.

1. Stop all work associated with damage to existing utilities, and notify the

Contracting Officer. Repair utility as directed by the Contracting Officer.

2. Repair at Contractor's expense underground utilities that are within 5 feet of where shown on Drawings, and damaged by the Contractor.

3. Repair at Government expense underground utilities not shown on Drawings or not within 5 feet of where shown on the Drawings, and damaged by the

Contractor.

4. Repair at Contractor's expense underground utilities marked on the ground or shown on Drawings, and damaged by the Contractor.

5. Repair at Government expense underground utilities not shown on Drawings or not marked on the ground, and damaged by the Contractor.

B. Surface Restoration.

1. Restore all surfaces in kind and in accordance with backfill classes indicated on Drawings:

a. Class A: Mound final uncompacted lift above finished grade.

b. Class D: Place crushed rock in 6 inch lifts or less and compact each lift with 6 passes of tamper. Trim and prime existing asphalt edges before patching. Mix temperature shall not be less than 240 degrees F at time of placement. Compact asphalt with truck or similar type construction vehicle in a direction parallel to the cut if possible. Begin compaction at and parallel to the edge of the patch.

2. Final Finish.

a. After the utility installation and backfill has been completed, finish all disturbed areas, except trench area required to be mounded, to a smooth, uniform grade and texture, well blended to the original contours, showing minimum evidence of construction activity.

C. Seeding.

1. Seed and fertilize all excavated and disturbed areas after restoration and scarifying.

2. Disturbed areas may be seeded or sodded at the Contractor's option. A

Government approved commercial sod may be substituted for replacement sod.

3.03 CLEANING

A. Disposal of Excess of Excavation and Unsuitable Material.

1. Haul excess (and unsuitable) material to the disposal site (shown on the

Drawings). Remove excess and unsuitable material from the site for disposal off National Forest Land.

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2. Spread excess excavation, without mounding, within the clearing limits.

END OF SECTION