02315_en.pdf

Section 02315 1

SECTION 02315

EXCAVATION AND FILL

PART 1 - GENERAL

1.1 APPLICABLE PUBLICATIONS

The following publications of the issues listed below, but referred to thereafter by basic designation only, form a part of this specification to the extent indicated by references thereto:

AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) PUBLICATIONS

D 1556-00 Standard Test Method for Density and Unit

Weight of Soil in Place by the Sand Cone

Method.

D 1557- 02 e1 Standard Test Methods for Laboratory

Compaction Characteristics of Soil Using

Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3).

D 2922- 01 Standard Test Methods for Density of Soil and Soil Aggregates in Place by Nuclear

Methods (Shallow Depth).

D 2487- 00 Standard Classification of Soils for

Engineering Purposes (Unified Soil

Classification System).

ITALIAN LAWS

Legislative Decree No. 494 (14 August 1996) Implementation of the instruction 92/57/CEE concerning the minimum safety and health requirements to be accomplished in temporary or mobile work sites.

1.2 SUBMITTALS

1.2.1 Certified Laboratory Test Reports

Before delivery of materials, certified copies in triplicate of the reports of all tests required herein under materials and in referenced publications shall be submitted to and approved by the Contracting

Officer. The testing shall have been performed in an independent laboratory approved by the Contracting Officer. Additional testing shall be submitted when the source of materials is changed. Certified test reports are required for the following:

a. Porous fill for capillary water barrier.

b. Select fill material

1.2.2 Field Test Reports

a. Fill and backfill test

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b. Select material test

c. Porous fill test for capillary water barrier

d. Density tests

1.2.3 Records

The Contractor shall submit a request for digging permit as required in paragraph 1.4 following.

1.3 SITE INFORMATION

The data on sub-surface soil conditions indicated in the contract drawings are not intended as representations or warranties of the continuity of such conditions between soil borings. It is expressly understood that the Government will not be responsible for any interpretation or conclusion drawn there from by the Contractor. The data are made available for the convenience of the Contractor.

Additional soil borings and other exploratory operations may be made by the Contractor at no additional cost to the Government, provided such operations are approved by the Contracting Officer.

1.4 EXISTING UTILITIES

Before starting mechanical earthwork operations, the Contractor shall obtain digging permits from the Contracting Officer. Requests for digging permits shall specify locations of work to be performed and date that the work is to begin. The locations of existing utilities indicated are approximate; the Contractor shall scan the construction site with electromagnetic and sonic equipment and mark the surface of the ground where existing underground utilities are discovered. The Contractor shall use manual methods to verify the location of underground utilities.

If utilities are to be left in place, protection against damage shall be provided. Existing utilities serving facilities occupied and used by the

Government shall not be interrupted except when approved in writing by the Contracting Officer and then after temporary utility services have been approved and provided.

1.5 MATERIAL STORAGE

Excavated materials classified as satisfactory soil material shall be stockpiled, where directed, until required for backfill or fill.

Stockpiles shall be placed, graded, and shaped for proper drainage, and stored in a manner to prevent contamination and segregation. Materials required in the work shall be located and retained a sufficient distance from the edge of excavations to prevent such material from falling or sliding back into the excavations, and to prevent cave-ins. Waste materials, such as excavated material classified as unsatisfactory soil material, trash, debris, and excess satisfactory soil material, shall be disposed of as specified hereinafter.

1.6 GENERAL REQUIREMENTS

Bids shall be based on the following:

a. That the surface elevations are as indicated.

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b. That no pipes or other artificial obstructions, except those indicated, will be encountered.

c. That hard material will not be encountered.

d. That ground water elevations indicated are those existing at the time subsurface investigations were made and do not necessarily represent permanent ground water elevation.

In case the actual conditions differ substantially from those stated or shown, the provisions of the contract respecting an adjustment for changed conditions shall apply, subject to the requirements of notification thereunder being given. Hard material shall be defined as solid rock, firmly cemented unstratified masses or conglomerate deposits possessing the characteristics of solid rock not ordinarily removed without systematic drilling and blasting and any boulder, masonry, or concrete except pavement, exceeding 0.4 cubic meters in volume.

PART 2 – PRODUCTS

2.1 POROUS FILL

Capillary water barrier (indicated as porous fill) under concrete floor slabs and areaways shall consist of clean crushed stone, crushed gravel, or uncrushed gravel, 90-100 percent passing a 20 millimeter sieve and 0-5 percent passing a 4.75 millimeter sieve with a sand equivalent of not less than 50 when tested in accordance with UNI EN 933-8. Porous fill may be composed of an appropriate combination of sand and crushed rock to meet the above gradation requirements. The capillary water barrier shall be placed directly on the subgrade. The barrier shall be constructed in layers not exceeding 10 centimeters in compacted thickness, and each layer shall be compacted with a minimum of two passes of a hand-operated plate type vibratory compactor.

2.2 SOIL MATERIALS

2.2.1 Satisfactory Soil Material

Satisfactory soil materials used as backfill for trenches, drains and for structures shall consist of native materials classified as well graded sands, silty sands or clayey sands which are free from debris, roots, wood, scrap materials and other vegetable matter and refuse.

2.2.2 Topsoil for Turfed Areas

Topsoil shall be from 5 to 10 percent organic matter, maximum particle size 10 millimeters (3/8 inch) with a maximum 3 percent retained on 6 millimeters (1-1/4 inch) sieve screen. Topsoil shall be free of sticks, stones, roots, and other debris and objectionable materials that is harmful or will hinder plant growth. Other components of the topsoil shall conform to the following limits:

pH 6.0 to 7.0

Soluble Salts 600 ppm maximum

Silt 25 to 50

Clay 10 to 30

Sand 20 to 35

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Topsoil may be stripped and stockpiled surface soil if it meets the above requirements or if it is conditioned to meet the above requirements.

Topsoil shall be obtained from an approved topsoil donor area.

2.2.3 Surface Soil

The top approximately 40 centimeters of existing soil which contains organic material.

2.2.4 Select Fill

Select fill material shall be composed of sand or crushed rock. This material shall have the following gradation:

Sieve Designation Percent Passing (Weight)

40 mm 75 a 85

4.75 mm 30 a 50

0.425 mm 5 a 15

2.2.5 Backfill and Fill Materials

Soil materials for backfill and fill shall be free of clay clods, rock or gravel larger than 6 centimeters in any dimension, debris waste, frozen materials, and other deleterious matter, and shall be satisfactory soil materials as follows:

Area Classification Backfill or Fill Material

In all excavations, unless otherwise specified hereinafter.

Excavated or borrow material that has been sampled, tested and approved as "Satisfactory Soil

Material."

Under grassed areas. Excavated or borrow material that has been sampled, tested and approved as "Satisfactory Soil

Material."

Under buildings. Select fill material and porous fill.

Under sidewalks and exterior concrete slabs

Select fill material.

2.2.6 Pipe Bedding Materials

a. Class I: Angular, 6 to 40 millimeters, graded stone, including a number of fill materials that have regional significance such as coral, slag, cinders, crushed stone and crushed shells.

b. Class II: Coarse sands and gravels with maximum particle size of

40 millimeters, including various graded sands and gravels containing small percentages of fines, generally granular and non-cohesive, either wet or dry. Soil Types GW, GP, SW, and SP are included in this class as specified in ASTM D 2487.

2.4 BURIED WARNING AND IDENTIFICATION TAPE

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Polyethylene plastic warning tape manufactured specifically for warning and identification of buried utility lines. Provide tape in rolls, 40 millimeters minimum width, color coded as specified below for the intended utility with warning and identification imprinted in bold black letters continuously over the entire tape length. Warning and identification to read, “ATTENZIONE, LINEE INTERRATE SOTTOSTANTI

(servizio interessato)” “CAUTION, BURIED (intended service) LINE BELOW" or similar wording. Color and printing shall be permanent, unaffected by moisture or soil.

Warning Tape Color Codes

Red Electric

Yellow Gas, Oil; Dangerous Materials

Orange Telephone and Other Communication Types

Blue Water Systems

Green Sewer Systems

Green Storm Systems

Light Blue Compressed Air

2.4.1 Bare Copper Tracer Wire for Non-Metallic Piping

Minimum diameter of the wire shall be 3 millimeters. Bare copper tracer wire shall be buried as shown on drawings, and shall terminate inside the manhole at each end.

PART 3 – EXECUTION

3.1 TOPSOIL

The top 10 centimeters thickness, or as otherwise shown, of all newly graded earth surfaced areas shall consist of topsoil. The topsoil shall be uniformly distributed on the designated areas and evenly spread to an average thickness of ten centimeters with a minimum thickness of eight centimeters, or as otherwise shown. Prior to placing the topsoil, the subgrade, wherever excessively compacted by traffic or other causes, shall be loosened by disking or by scarifying to a depth of at least 6 centimeters, to permit bonding to the subgrade. The spreading shall be performed in such a manner that planting can proceed with little additional soil preparation or tillage. Any irregularities in the surface resulting from topsoiling or other operations shall be corrected in order to prevent the formation of depressions where water will stand.

Topsoil shall not be placed when the subgrade is excessively wet, extremely dry, or in a condition otherwise detrimental to proper grading.

3.2 EXCAVATION

3.2.1 General

Excavation shall consist of the removal and disposal of all materials encountered to obtain the specified subgrade elevations. Strip existing surface soil to minimum 40 centimeter depth, unless otherwise noted.

3.2.2 Protection of Persons and Property

All excavations shall be barricaded and posted with warning signs for people safety. Warning lights shall be provided during hours of darkness.

Structures, utilities, sidewalks, pavements and other facilities

6 Section 02315 immediately adjacent to excavations shall be protected against damage including settlement, lateral movement, undermining, and washout.

3.2.3 Excavation for Structures

Excavation for structures shall conform to the dimensions and elevations indicated within a tolerance of plus or minus 15 centimeters and shall extend a sufficient distance from footings and foundations to permit placing and removal of concrete formwork, installation of services and other construction indicated, and for inspection, but not less than 1.50 meters from the sides of foundations. In excavations for footings and foundations, take care not to disturb the bottom of the excavation.

Excavate to final grade just before concrete is placed. Trim bottoms to the required lines and grades to leave a solid bed to receive concrete.

3.2.4 Trench Excavation

Trenches shall be of necessary width for proper pipe, duct or cable laying and banks shall be as nearly vertical as practicable. Bottoms of trenches shall be accurately graded to provide uniform bearing and support for each section of pipe on undisturbed soil at every point along its entire length, except for portions of pipe sections where it is necessary to excavate for bells and for proper making of joints and to allow for the indicated thickness of select fill bedding. Bell holes and depressions for joints shall be shaped after bedding bottom has been graded and shall be only one centimeter greater in length, depth and width than the bell, as required for properly making the particular type of joint, and to insure that the bell does not bear an undue portion of the load. When hard materials are encountered, trenches shall be cut to an over-depth of at least ten centimeters including bell holes, and back-filled to required grade as specified hereinbefore when hard materials are not encountered. Trenches shall then be backfilled as previously specified for areas where hard material is not encountered.

3.2.5 Excavation for Roads and Parking Areas

Excavation shall consist of excavating and grading for parking areas;

excavating the top 40 centimeters of surface soil and additional unsuitable material, regardless of character, from the subgrade; and disposing of all excavated materials, as specified and in conformity with the lines, grades, cross sections, and dimensions shown on the drawings, and to replace unsatisfactory materials from other excavation or grading operations.

3.2.6 Removal of Unsatisfactory Soil Materials

Unsatisfactory soil materials encountered that extend below the required elevations shall be excavated to the depth directed by the Contracting

Officer’s Technical Representative. Such additional work, provided it is not due to the fault or neglect of the Contractor, shall be measured as directed by the Contracting Officer and paid for by the Government in accordance with the "Special Requirements" relative to changes in the work. Where unsatisfactory soil materials result from the neglect of the

Contractor in his performance of shoring and bracing, water removal, material storage, or other specified requirements, the resulting unsatisfactory soil material as hereinafter specified shall be removed and replaced at no additional cost to the Government.

3.2.7 Unauthorized Excavation

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Unauthorized excavation shall consist of removal of materials beyond indicated subgrade elevations or side dimensions specified without the specific direction of the Contracting Officer’s Technical Representative and shall be replaced as hereinafter specified at no additional cost to the Government. Unauthorized excavation under the footing or base of foundation or retaining wall shall be filled to the elevation of the footing or base with lean concrete (Rck = 200 kilograms per square centimeter) or well-compacted select fill, without altering the approved top elevation. Elsewhere unauthorized excavations shall be backfilled and compacted as specified for authorized excavations of the same classification.

3.2.8 Stability of Sides

Sides of excavations over 1.5 meters in depth shall be sloped to the angle of repose of the material excavated, or shall be shored and braced where sloping is not possible either because of space restrictions or stability of material excavated. Sides and slopes of excavations shall be maintained until completion of backfill placement in a safe condition by scaling, benching, shelving, or bracing. Precautions shall be taken to prevent slides or cave-ins when excavations are made in locations adjacent to backfilled excavations, and when sides of excavations are subjected to vibrations from vehicular traffic or the operation of machinery or any other source.

3.2.9 Shoring and Bracing

Materials used for shoring and bracing, such as sheet piling, uprights, stringers and crossbraces, shall be in good serviceable condition. Any timber used shall be sound and free of large or loose knots. Shoring and bracing in excavations shall be maintained regardless of the length of time excavations will be open. All shoring and bracing shall be carried down with the excavation. Wherever subsequent removal of sheet piling could permit the lateral movement of soil under adjacent structures, steel sheet piling or pressure creosote timber sheet piling shall be used, and left permanently in place, and cut off as required.

3.2.10 Water Removal

Excavation shall be performed in a manner to prevent surface water and subsurface or ground water from flowing into the excavations and to prevent water from flooding the project site and surrounding area. Water shall not be permitted to accumulate in excavations. All water shall be removed from excavations by approved dewatering methods so that softening of foundation bottom, undercutting footings, and soil changes detrimental to the stability of subgrades and foundation will not occur. Pumps, sumps, suction and discharge lines, and other dewatering system components shall be provided and maintained as necessary to convey the water away from the excavations. Dewatering operations shall be continued until the completion of backfill placement and until construction subject to water pressure has obtained the specified strength. In all instances, dewatering operations shall continue as long as water can enter or accumulate in the excavations. Water removed from excavations and rainwater shall be conveyed to collecting or run-off areas, as approved by the Contracting Officer’s Technical Representative.

Temporary drainage ditches and other diversions shall be provided and maintained outside the excavation limits for each structure. The use of

8 Section 02315 trench excavations for site utilities as temporary drainage ditches will not be permitted.

3.3 BACKFILL AND FILL

3.3.1 General

Backfill shall consist of the placement of specified backfill material, in layers, in the excavations to the indicated subgrade elevations, for each area classification listed below.

Fill shall consist of the placement of specified fill materials, in layers, over the ground surface to the indicated elevations, for each area classification listed below.

3.3.2 Preparations Prior to Backfill Placement

Excavations shall be backfilled as promptly as the work permits, but not until completion of the following:

a. Approval of construction below finish grade.

b. Inspection, testing, approval, and recording location of underground utilities.

c. Removal of concrete formwork.

d. Removal of shoring and bracing, and backfilling of voids with satisfactory soil material; temporary sheet piling driven below the bottom of structure and utilities shall be cut off and removed in a manner to prevent settlement of the structure or utilities.

e. Removal of trash and debris.

3.3.3 Preparation of Ground Surface to Receive Fill

Vegetation, debris, unsatisfactory soil materials, obstructions, and deleterious materials shall be removed from ground surface prior to the placement of fills. Sloped surfaces steeper than one vertical to four horizontal shall be plowed, stripped, or broken-up in such a manner that fill material will bond with the existing material. When the ground surface has a density less than that specified for the particular area classification, the ground surface shall be broken-up, pulverized, moisture-conditioned to near optimum moisture content of the soil material and compacted to the required depth and percentage of maximum density.

3.3.4 Backfilling Trenches

Backfilling shall be coordinated with testing of utilities. Where damage is likely to result from withdrawing sheeting, the sheeting shall be left in place and contract price will be adjusted accordingly. Trenches shall be carefully backfilled with materials hereinbefore specified or as indicated, and deposited in 20 centimeters maximum layers, loose depth.

Borrow materials shall be obtained from sources outside the station. The source of material shall be the Contractor's responsibility. Backfill shall be brought up evenly on both sides of pipe for its full length, and shall be thoroughly and carefully tamped. Care should be taken not to damage pipe or special coatings on pipe.

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The remainder of backfill material shall then be deposited in the trench in 30 centimeters maximum layers and compacted by mechanical means.

Trenches and excavation pits improperly backfilled, or where settlement occurs, shall be reopened to the depth required to obtain the specified compaction, then refilled and compacted with the surface restored to the required grade and compaction.

3.3.4.1 Buried Identification Tape and Bare Copper Tracer Wire for non metallic buried utility lines

Provide buried utility lines with utility identification tape. Bury tape

300 millimeters below finished grade; under pavements and slabs, bury tape 150 millimeters below top of subgrade. Bare copper tracer wire shall be installed as shown on drawings. Install a continuous length of tracer wire for the full length of each run of nonmetallic pipe. Attach wire in such manner that it will not be displaced during construction operations.

3.3.5 Subgrade Preparation for Roadways and Parking

After the grading is substantially complete, and immediately in advance of depositing the surfacing material, the subgrade shall be brought to the proper lines, grades, and cross sections as indicated and in accordance with these specifications. All depressions and ruts shall be removed by blading and dragging so as to secure a uniform surface. The entire subgrade shall be brought to a firm, unyielding surface, true to line, grade and cross section, by rolling with an approved power roller, weighing not less than 9500 kilograms, until thoroughly compacted. This operation shall include any reshaping and wetting required to obtain proper compaction. All soft, spongy, or yielding spots shall be entirely removed and the space refilled with suitable material and thoroughly compacted. The top of the subgrade shall be of such smoothness that when tested with a 5 meters straightedge it shall not show any deviation greater than 12 millimeters.

Subgrade compaction shall be extended onto the shoulders for a distance of at least 30 centimeters beyond the edges of the base course or pavement. The subgrade shall be maintained in the finished condition until the first course of surfacing has been placed.

3.3.6 Preparation of Planting Areas

Planting areas, as indicated, shall be graded to the dimensions, elevations, and cross sections indicated on the drawings. The top 10 centimeters, or as otherwise shown, of such areas shall consist of topsoil as defined herein, which shall be lightly compacted. All material below the topsoil layer shall be compacted as specified for subgrade preparation.

3.4 COMPACTION

3.4.1 General

The compaction of soil materials for backfills and fills shall be performed by use of the specified compaction equipment that is suitable for the soil material being compacted and for use in the location of the work area. Soil compaction shall be controlled during construction for compliance with the percentage of maximum density for each area classification as specified.

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3.4.2 Compaction Equipment

All compaction equipment shall be of suitable size and number, and in satisfactory working condition to complete the work on schedule.

Compaction equipment shall consist of pneumatic tired rollers, tamper rollers, vibrating tampers, or other compaction equipment suitable for the soil material being compacted and capable of obtaining the required density throughout the entire layer being compacted.

3.4.3 Placement and Compaction

Backfill and fill materials shall be placed in layers not more than 20 centimeters in loose depth. Before compaction, each layer of backfill or fill material shall be moistened or aerated as necessary to provide the optimum moisture content of the soil material, and shall then be compacted to the percentage of maximum density for each area classification as specified. No backfill or fill material shall be placed on surfaces that are muddy, frozen, or contain frost, or ice.

Backfill and fill materials adjacent to structures shall be brought-up evenly around the structures, and shall be carried up to the indicated elevations.

Compaction adjacent to structures, within a horizontal distance from the face of the structure equal to the depth of backfill or fill material

(measured from the bottom of footing or bottom of foundation or retaining wall) to final grade, shall be done with power-driven hand tampers.

3.4.4 Degree of Compaction

Except where otherwise specified, the degree of compaction and density shall be determined and controlled in accordance with the requirements of

ASTM D 1557.

3.4.5 Field determination of the density of soils in place shall be in accordance with ASTM D 1556 or ASTM D 2922.

3.4.6 Compaction

The subgrade of soils in cut shall have a density of at least 95 percent of the maximum density to a depth of 30 centimeters below the subgrade surface. If the density of the existing material is less than 95 percent, it shall be compacted to a depth of 30 centimeters to the minimum 95 percent density. Fill, embankment, and/or backfill under concrete floor slabs and the upper 30 centimeters under paved areas shall be compacted to not less than 95 percent of the maximum density; other backfill adjacent to and not supporting any structural elements to at least 90 percent. The upper 30 centimeters of trenches shall be compacted to at least 95 percent maximum density.

3.4.7 Moisture Control

Provide equipment capable of adding measured amount of water as determined by moisture-density relation tests. The moisture content in the soil material at the time of compaction shall be within plus or minus two percent of optimum. For unsatisfactory soil materials where the subgrade or layer of soil material must be moisture conditioned before compaction, the required amount of water shall be uniformly applied to the surface of subgrade or layer of soil material in such manner as to prevent free water appearing on the surface during or subsequent to

Section 02315 11 compaction operations. Any soil material that is too wet to permit compaction to specified percentage of maximum density shall be removed and replaced with satisfactory soil material. Soil material that has been removed because it is too wet to permit compaction may be stockpiled or spread on the surface where directed by the Contracting Officer’s

Technical Representative and permitted to dry, assisted by disking, harrowing or pulverizing, until the moisture content is reduced to a satisfactory value as determined by moisture-density relation tests, after which the soil material may be used in compacted backfill or fill.

3.5 GRADING

3.5.1 General

All areas within the limits of grading under this section, including adjacent transition areas, shall be uniformly graded. The finished surface shall be smooth within the specified tolerances, compacted, and with uniform levels or slopes between points where elevations are indicated, or between such points and existing grades.

3.5.2 Grading Outside Building Lines

The areas outside the building lines for each structure shall be hand graded to drain away from the structure and to prevent ponding of water after rains. The finished surface shall be within the tolerance specified below for each area classification, compacted as specified, and free from irregular surface changes.

3.5.2.1 Grassed Areas

The finished surface of areas to receive topsoil shall be not more than 3 centimeters above or below the indicated subgrade elevations.

3.5.2.2 Walks

The surface of areas under walks shall be shaped to line, grade and cross-section, and finished surface shall not be above nor more than 3 centimeters below the indicated subgrade elevation.

3.6 REMOVAL FROM GOVERNMENT PROPERTY

Waste materials, including excavated material classified as unsatisfactory or excess soil material, trash and debris, shall be removed from Government property and legally disposed of at no additional cost to the Government. All permits and fees for disposal shall be paid by the Contractor. Contractor shall remove debris and loose materials and clean paved areas, adjacent to work site, at the end of each working day.

3.7 PROTECTION OF GRADED AREAS

Newly graded areas shall be protected from traffic and erosion, and shall be maintained free of trash or debris. Repair and reestablish grades in settled, eroded, and rutted areas to the satisfaction of the Contracting

Officer’s Technical Representative.

3.8 RECONDITIONING COMPACTED AREAS

Where approved compacted areas are disturbed by subsequent construction operations or adverse weather, the surface shall be scarified, re-shaped, 12 Section 02315 and compacted as specified hereinbefore to the required density prior to further construction thereon. Recompaction over underground utilities shall be by hand tamping.

3.9 FIELD SAMPLING AND TESTING

3.9.1 Testing

All testing shall be conducted by the Contractor as specified herein at the expense of the Contractor.

3.9.2 Submittals

3.9.2.1 Field Test Reports

a. Porous Fill Testing: Gradation test shall be made on each sample.

Tests shall be performed for each 100 cubic meters of material used or fraction thereof and whenever the source is changed.

b. Compaction Testing: Compaction tests shall be made in locations as selected by the Contracting Officer’s Technical Representative as follows:

Materials Test Frequency

(1) Fill and Backfill 1 per lift per every 800 m2

(2) Subgrade (existing 1 per lift per every 800 m2 in situ density)

(3) Fill in trenches under 1 per lift per every 200 lm of trench pavement

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