Attachment 14 Specification Guide 02221 ExBackSite.pdf

Attachment 14 – Specification Guide 02221 – Excavation, Backfilling, and Site Restoration

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. The most current version of each document shall be used.

AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

ASTM D 1556 / D1556M-15e1 (2015) Standard Test Method for Density and Unit Weight of Soil in Place by the Sand-Cone Method

ASTM D 1557-12e1 (2012) Standard Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/cu. ft. (2,700 kn-m/cu.m.))

ASTM D 2167 (2015) Standard Test Method for Density and Unit Weight of Soil in Place by the Rubber Balloon Method

ASTM D 2216-19 (2019) Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass

ASTM D 2487-17e1 (2020) Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)

ASTM D 2922 (2017) Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)

ASTM D 2937-17e2 (2018) Standard Test Method for Density of Soil in Place by the Drive- Cylinder Method

ASTM D 6938-17a (2017) Standard Test Method for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)

ASTM D 4318 (2018) Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils

1.2 DEFINITIONS

1.2.1 Degree of Compaction

Degree of compaction required is expressed as a percentage of the maximum density obtained by the test procedure presented in ASTM D 1557 abbreviated hereinafter as percent laboratory maximum density.

1.3 SUBMITTALS

The following shall be submitted in accordance with SPECIAL CONTRACT

REQUIREMENTS:

SD-09 Reports

Field Density Tests; GA. Testing of Backfill Materials Copies of all laboratory and field test reports within 24 hours of the completion of the test.

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Satisfactory Materials

Satisfactory materials include only local borrow from the demolition sites and/or crushed concrete resulting from the crushing of the demolished concrete. Materials classified in ASTM D 2487 as GW, GP, SW, and shall be free of trash, debris, roots or other organic matter, or stones larger than 75 mm (3 inches) in any dimension. After completion of clearing and grubbing, topsoil shall be removed and stockpiled for placement at the completion of final grading.

2.1.2 Unsatisfactory Materials - NA

2.1.3 Cohesionless and Cohesive Materials - NA

PART 3 EXECUTION

Prior to any underground excavation, including excavation for utilities, the contractor shall call and obtain approval in writing from the host installation Department of Public Works. A copy of the approval notification must be available for inspection at the excavation site. Pertinent phone numbers shall be provided upon issuance of delivery orders for those locations.

3.1 CLEARING AND GRUBBING

The areas immediately adjacent to structures to be removed shall be cleared and grubbed of all vegetation. It is the responsibility of the Contractor to properly collect, store, transport, and dispose of the cleared materials.

3.2 TOPSOIL

Topsoil to be placed in final grading shall be provided from the re-grading of the demolition site in accordance with the elevations shown on the drawings.

3.3 EXCAVATION

Excavation shall occur only where it is necessary for the removal of foundations, UST’s and piping. Excavations shall be backfilled, as specified herein, immediately after removal of foundations and other underground improvements.

3.4 DRAINAGE

3.4.1 Drainage

Surface water shall be directed away from excavation and construction sites so as to prevent erosion. Diversion ditches, dikes and grading shall be provided and maintained as necessary during demolition. Excavated slopes and backfill surfaces shall be protected to prevent erosion and sloughing. Excavation shall be performed so that the site and the area immediately surrounding the site and affecting operations at the site shall be continually and effectively drained.

3.5 SHORING

Shoring, including sheet piling, shall be furnished and installed as necessary to protect workmen, banks, adjacent paving, structures, and utilities. Shoring, bracing, and sheeting shall be removed, as excavations are backfilled, in a manner to prevent caving.

3.6 CLASSIFICATION OF EXCAVATION

Excavation shall be unclassified regardless of the nature of material encountered.

3.7 BLASTING (Blasting shall not be permitted.)

3.8 BORROW

Where satisfactory materials are not available in sufficient quantity from required excavations, approved materials shall be obtained as directed by the COR.

3.9 EXCAVATED MATERIALS

Satisfactory excavated material required for fill or backfill shall be placed in the proper section of the permanent work required under this section or shall be separately stockpiled if it cannot be readily placed.

3.10 FILLING AND BACKFILLING

Satisfactory materials shall be used in bringing fills and backfills to the lines and grades indicated and for replacing unsatisfactory materials. Satisfactory materials shall be placed in horizontal layers not exceeding 200 mm (8 inches) in loose thickness, or 150 mm (6 inches) when hand-operated compactors are used. After placing, each layer shall be plowed, disked, or otherwise broken up, moistened or aerated as necessary, thoroughly mixed and compacted as specified. Backfilling shall not begin until demolition and removal below finish grade has been approved and underground utilities systems have been removed and capped as shown on the drawings. Backfill shall be brought to indicated finish grade. Backfill shall not be placed in wet or frozen areas. Each layer of fill and backfill shall be compacted to not less than the percentage of maximum density specified below:

Location Cohesive material Cohesionless material

Under structures, building slabs, Steps, paved areas, around footings, and in trenches

90 95

Under sidewalks and grassed areas 85 90

Approved compacted sub grades that are disturbed by the Contractor's operations or adverse weather shall be scarified and compacted as specified herein before to the required density prior to further construction thereon.

3.11 TESTING

Testing shall be the responsibility of the Contractor and shall be performed at no additional cost to the Government. Testing shall be performed by an approved commercial testing laboratory or may be performed by the Contractor subject to approval. Field in-place density shall be determined in accordance with ASTM D 1556, ASTM D 2167, or ASTM D 2922. When ASTM D 2922 is used, the calibration curves shall be checked and adjusted if necessary by the procedure described in ASTM D 2922, paragraph ADJUSTING CALIBRATION CURVE.

ASTM D 2922 results in a wet unit weight of soil and when using this method ASTM D 6938 shall be used to determine the moisture content of the soil. The calibration curves furnished with the moisture gauges shall also be checked along with density calibration checks as described in ASTM D 6938. The calibration checks of both the density and moisture gauges shall be made at the beginning of a job on each different type of material encountered and at intervals as directed by the QAR. ASTM D 2937 shall be used only for soft, fine-grained, cohesive soils. The following number of tests, if performed at the appropriate time, shall be the minimum acceptable for each type operation.

3.11.1 In-Place Densities

3.11.1.1 In-Place Density of Sub grades

One test per 1,000 square feet or fraction thereof.

3.11.1.2 In-Place Density of Fills and Backfills

One test per 10,000 square feet or fraction thereof of each lift for fill or backfill areas compacted by other than hand or hand-operated machines. The density for each lift of fill or backfill materials for trenches, pits, building perimeters or other structures or areas less than 10 feet in width, which are compacted with hand or hand-operated machines shall be tested as follows: One test per each area less than 1,000 square feet.

3.12 GRADING

Grading shall conform to the grades and elevations shown on the drawings. Areas within 3.0 m (10 feet) outside of each building and structure line shall be constructed true-to-grade, shaped to drain, and shall be maintained free of trash and debris until final inspection has been completed and the work has been accepted.

3.13 SPREADING TOPSOIL

Areas outside the building lines from which topsoil has been removed shall be brought to grade with stockpiled topsoil. The surface shall be free of materials that would hinder planting or maintenance operations. The sub-grade shall be pulverized to a depth of 50 mm (2 inches) by disking or plowing for the bonding of topsoil with the subsoil. Topsoil shall then be uniformly spread, graded, and compacted to the thickness, elevations, slopes shown, and left free of surface irregularities. Topsoil shall be compacted by one pass of a cultipacker, roller, or other approved equipment weighing 1.46 kn/m to 2.34 kN/m (100 to 160 pounds per linear foot) of roller.

Topsoil shall not be placed when the sub-grade is frozen, excessively wet, extremely dry, or in a condition otherwise detrimental to seeding, planting, or proper grading.

3.14 SOIL SURFACE RESTORATION

Contractor is responsible of the seeding, sodding, or return to some other defined native condition. [Refer to Specification Section 02921 for products, materials, preparation, and restoration options.]

3.14.1 Soil Conditioning.

Define required soil conditioner (lime, sulfur, peat, sand, compost, gypsum, etc.) and application rate to be used by Contractor.

3.14.2 Seed Material.

Define the required type of seed, method of application (hydro seed, broadcast, plugging) and rate of application.

3.14.3 Fertilizer.

Define product to be used, if any, and method and rate of application. Fertilizer specification usually consists of an organic, synthetic, or hydro fertilizer applied by a spray or broadcast method.

3.14.4 Mulch and Erosion Control.

Straw, hay, wood cellulose fiber mulch is normally used to protect the seeded material and prevent soil erosion until the seed has germinated and established.

3.15 PROTECTION

Settlement or washing that occurs in graded, topsoil, or backfilled areas prior to acceptance of the work shall be repaired and grades reestablished to the required elevations and slopes at no additional cost to the Government.

END OF SECTION