31 23 16.pdf

Tinker AFB, OK TAFB Technical Specifications 2019

April 2019 Page 1 Section 31 23 16

SECTION 31 23 16

EXCAVATION, TRENCHING, AND BACKFILLING FOR UTILITIES

PART 1 GENERAL

1.1 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by basic designation only. Unless specifically noted, the current edition of the reference will be used.

AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

ASTM D 1556 Density and Unit Weight of Soil in Place by the Sand-Cone Method

ASTM D 1557 Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/cu. ft. (2,700 kN-m/cu. m.))

ASTM D 2167 Density and Unit Weight of Soil in Place by the Rubber Balloon Method

ASTM D 2487 Classification of Soils for Engineering Purposes (Unified Soil Classification System)

ASTM D 2922 Density of Soil and Soil-Aggregate in

Place by Nuclear Methods (Shallow Depth)

ASTM D 3017 Water Content of Soil and Rock in Place by Nuclear Methods (Shallow Depth)

1.2 SUBMITTALS

Government approval is required for all submittals. The following shall be submitted in accordance with SECTION 01 33 00; SUBMITTAL

PROCEDURES:

SD-06 Test Reports

Compaction Test

Copies of all laboratory and field test reports shall be submitted within two working days of the completion of the test.

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1.3 DESCRIPTION OF WORK

This specification covers the furnishing and installation of materials for excavation, trenching, and backfilling for utilities systems.

1.4 DEGREE OF COMPACTION

Degree of compaction shall be expressed as a percentage of the maximum density obtained by the test procedure presented in ASTM D 1557.

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Satisfactory Materials

Satisfactory materials shall comprise any materials classified by ASTM D 2487 as GW, GP, GM, SW, SM, ML, SP and CL.

2.1.2 Unsatisfactory Materials

Materials, which do not comply with the requirements for satisfactory materials, are unsatisfactory. Unsatisfactory materials also include man-made fills, trash, refuse, or backfills from previous construction. Unsatisfactory material also includes material classified as satisfactory, which contains root and other organic matter, frozen material, and stones larger than 4 inches. The Contracting Officer shall be notified of any contaminated materials.

2.1.3 Cohesionless and Cohesive Materials

Cohesionless materials shall include materials classified in ASTM D 2487 as GW, GP, and SW. Cohesive materials shall include materials classified as GC, SC, ML, CL, MH, and CH. Materials classified as GM and SM shall be identified as cohesionless only when the fines are non-plastic.

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2.1.4 Select Granular Material

Select granular material shall consist of well-graded sand meeting the following gradation:

Sieve Size Percent Passing

3/8 in. 100 No. 4 95-100 No. 16 50-85 No. 50 15-33 No. 100 0-10

2.2 PLASTIC MARKING TAPE

Plastic marking tape shall be acid and alkali-resistant polyethylene film, 6 inches wide with minimum thickness of 0.004 inch. Tape shall have a minimum strength of 1750 psi lengthwise and 1500 psi crosswise. The tape shall be manufactured with integral wires, foil backing or other means to enable detection by a metal detector when the tape is buried up to 3 feet deep.

The tape shall be of a type specifically manufactured for marking and locating underground utilities. The metallic core of the tape shall be encased in a protective jacket or provided with other means to protect it from corrosion. Tape color shall be as specified in TABLE 1 and shall bear a continuous printed inscription describing the specific utility.

TABLE 1

Color Utility

Red: Electric Yellow: Gas, Oil, Dangerous Materials Orange: Telephone, Telegraph, Television, Police and Fire Communications Blue: Water Distribution Systems Green: Sanitary and Storm Sewer Systems

PART 3 EXECUTION

3.1 EXCAVATION

All excavation will be unclassified. Excavate to depths indicated and as specified. Store material sufficient distance from the banks to prevent slides or cave-ins. Remove and dispose of all excavated materials not required or suitable for backfill.

During construction, provide drainage and pumps as necessary so that excavation, installation, and backfill shall be in the dry For trenches or excavations 4 feet or more in depth, shore or brace sides of excavation or slope as required to maintain stable slopes.

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3.1.1 Trench Excavation Requirements

The trench shall be excavated as recommended by the manufacturer of the pipe to be installed. Excavate sides of trenches as nearly vertical as practicable. Accurately grade the bottom to provide uniform bearing and support for each section of the pipe on undisturbed soil along its entire length. After the trench bottom has been graded, provide bell holes and depressions only of such length, depth, and width as required for joints. Remove stones to avoid point bearing. Excavate rock to 6 inches below the trench depth required. Backfill over depth to the proper grade with materials specified for backfilling lower portion of trenches. Where recommended trench widths are exceeded, the Contractor shall utilize redesign, stronger pipe, or special installation procedures. The cost of redesign, stronger pipe, or special installation procedures shall be borne by the Contractor without any additional cost to the Government.

3.1.2 Removal of Unstable Material

Where unstable material is encountered in the bottom of the trench, such material shall be removed to the depth directed and replaced to the proper grade with select granular material as provided in Paragraph 3.3, BACKFILL. When removal of unstable material is required due to the Contractor's fault or neglect in performing the work, the resulting material shall be excavated and replaced by the Contractor without additional cost to the Government.

3.1.3 Storm Drains

Below top of pipe, provide an 8-inch space between the barrel of the pipe and the side of the trench. Excavate the trench above the top of the pipe as necessary for sheeting, bracing, and installation. Manually round bottom of trench so that bottom quadrant of pipe rests firmly on undisturbed soil.

3.1.4 Electrical Systems

Sides of trenches for electrical cables and duct lines may be sloped or widened as required provided there is no interference with other utilities. Special trenching requirements for direct-buried cable and conduit or duct lines are specified in Section 33 70 02; ELECTRICAL DISTRIBUTION, UNDERGROUND.

3.1.5 Excavation for Manholes and Similar Structures

Provide at least 12 inches between the outer structure surfaces and the sides of the excavation or shoring, etc. Any over depth excavation shall be considered unauthorized and shall be

April 2019 Page 5 Section 31 23 16 backfilled with sand, gravel, or concrete, as directed by the Contracting Officer at no cost to the Government.

3.2 REMOVAL OF UTILITY LINES

The Contractor shall notify the Contracting Officer at least 72 hours prior to removal, so that necessary measures can be taken to prevent interruption of service.

3.3 BACKFILL

Backfill the excavation to the required elevation after required pressure testing has been completed. Restore the surface to its original condition as near as practicable. Replace pavement, base course, and compacted subgrade with materials equal to the adjacent materials for a minimum of 12 inches on each side of the trench.

3.3.1 Lower Portion of Trench

Deposit backfill in six inch layers and compact to a density of 95 percent of maximum, until there is a cover of two feet over sewers and one foot over other utilities. Material for backfill shall be material at a moisture content that will facilitate compaction and be free from stones larger than three inches;

except that backfill material used within one foot of coated or wrapped pipe shall be free from stones. Do not damage coating or wrapping.

3.3.2 Remainder of Trench

Backfill material shall be free from stones larger than six inches in any dimension or one half of the layer thickness in any dimension, whichever is smaller. Deposit backfill in the layer thickness specified and compact each layer to the specified density.

3.3.3 Under Pavements

Deposit backfill in six inch layers and compact cohesive soils to 95 percent maximum density and cohesionless soils to maximum density. Place backfill to the elevation at which the requirements for pavement subgrade materials and compaction control.

3.3.4 Under Seeded or Sodded Lawn Areas and Sidewalks

Deposit backfill in 12 inch layers and compact cohesive soils to 90 percent maximum density and cohesionless soils to 95 percent of maximum density.

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3.3.5 Other Areas

Deposit backfill in 12 inch layers and compact to 85 percent of maximum density.

3.4 SPECIAL REQUIREMENTS

Special requirements for both excavation and backfill relating to the specific utilities are as follows:

3.4.1 Plastic Marking Tape

Warning tapes shall be installed directly above the pipe or cable, at a depth of 18 inches below finished grade unless otherwise shown.

3.5 TESTING

Copies of compaction tests will be furnished to the Contracting Officer within two working days. Compaction tests will be made on the basis of one test per lift per workday. Where the trench is underneath the pavement, tests shall be made at the rate of at least one test per lift, per street crossing or 500 linear feet of trench.

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2.2 PLASTIC MARKING TAPE

3.5 TESTING