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    SECTION 02220

    EXCAVATION, BACKFILLING, COMPACTION

   PART 1 - GENERAL

   1.01 Section Includes

   A. Excavation for building foundations.

   B. Excavation for paving and landscaping.

   C. Excavation for site structures.

   D. Excavation for Mechanical/Electrical Work: Excavation and backfill required in conjunction with underground mechanical and electrical utilities, and buried mechanical and electrical appurtenances.

   E. Backfilling of trenches.

   F. Building perimeter and site structure backfilling to subgrade elevations.

   G. Site filling and backfilling.

   H. Fill under slabs-on-grade and paving.

   I. Fill over over-excavation.

   J. Consolidation and compaction.

   K. Sheet vapor retardant and cover over crawl space and fill.

   1.02 Reference Standards

    A. Abbreviations and acronyms for reference standards are defined in Section 01090-Reference Standards.

   B. ANSI/ASTM C136 - Method for Sieve Analysis of Fine and Coarse Aggregates.

   C. ANSI/ASTM D698 - Test Methods for Moisture-Density Relations of Soils and Soil-Aggregate Mixtures, Using 5.5 lb. Rammer and 12 inch Drop.

   D. ANSI/ASTM D2922 - Test Method for Density of Soil in Place by the Nuclear Method.

   E. ANSI/ASTM D1557 - Test Methods for Moisture-Density Relations of Soils and Soil-Aggregate Mixtures Using 10 lb. Rammer and 18 inch Drop.

   F. ASTM D2478 - Soil Classification.

   1.03 Quality Assurance

   A. Codes and Standards: Perform excavation work in compliance with applicable requirements of governing authorities having jurisdiction.

   B. Employ, at Contractor's expense, testing laboratory to perform soil testing and inspection service for quality control testing during earthwork operations.

   1.04 Submittals

   A. Test Reports-Excavating: Submit following reports directly to Engineer from the testing services, with copy to Contractor:

   1. Test reports on borrow material.

   2. Verification of each footing subgrade.

   3. Field density test reports.

   4. One optimum moisture-maximum density curve for each type of soil encountered.

   5. Report of actual unconfined compressive strength and/or results of bearing tests of each strata tested.

   1.05 Job Conditions

   A. Test borings and other exploratory operations may be made by Contractor at no cost to Owner.

   B. Verify that survey benchmark and intended elevations for the Work are as indicated.

   C. Existing Utilities: Locate existing underground utilities in areas of work. If utilities are to remain in place, provide adequate means of support and protection during earthwork operations.

   D. Should uncharted, or incorrectly charted, piping or other utilities be encountered during excavation, consult utility owner immediately for directions. Cooperate with Owner and utility companies in keeping respective services and facilities in operation. Repair damaged utilities to satisfaction of utility owner.

   E. Do not interrupt existing utilities serving facilities occupied and used by Owner or others, during occupied hours, except when permitted in writing by Engineer and then only after acceptable temporary utility services have been provided.

   1. Provide minimum of 48-hour notice to Engineer, and receive written notice to proceed before interrupting any utility.

   F. Demolish and completely remove from site existing underground utilities indicated to be removed. Coordinate with utility companies for shut-off of services if lines are active.

   1.06 Use of Explosives

    A. Any material that is encountered within the limits of the required excavation that cannot be removed except by drilling and/or blasting, including rock, boulders, masonry, hard pan, chert, shale, street and sidewalk pavements, and/or similar materials, shall be considered as unclassified excavation, and no separate payment will be made therefor.

   B. Should rock be encountered in the excavation, remove it by blasting or otherwise. Where blasts are made, cover the excavation with enough excavation material and/or timber or steel matting to prevent danger to life and property. The Contractor shall secure, at his own expense, all permits required by law for blasting operations and the additional hazard insurance required. Observe all applicable laws and ordinances pertaining to blasting operations.

   C. Protection of Persons and Property: Barricade open excavations occurring as part of this work and post with warning lights.

   D. Operate warning lights as recommended by authorities having jurisdiction.

   E. Protect structures, utilities, sidewalks, pavements, and other facilities from damage caused by settlement, lateral movement, undermining, washout and other hazards created by earthwork operations.

   PART 2 - PRODUCTS

   2.01 Soil Materials

   A. Geotechnical Engineer and testing service to be on-site to determine satisfactory and unsatisfactory soils materials.

   B. Drainage Fill: Washed, evenly graded mixture of crushed stone, or crushed or uncrushed gravel, with 100% passing a 1-1/2" sieve and not more than 5% passing a No. 4 sieve.

   C. Backfill and Fill Materials: Satisfactory soil materials of clay, rock or gravel not larger than 2" in any dimension, free of debris, waste, frozen materials, vegetable and other deleterious matter.

   D. Type A - Crushed Stone/Gravel: Graded in accordance with T.D.O.T. Section 303.01.

   E. Type B - Natural stone; free of clay, shale, organic matter; graded in accordance with ANSI/ASTM C136, to the following:

   1. Minimum Size: 1/4 inch.

   2. Maximum Size: 5/8 inch.

   F. Type C - Sand: free of silt, clay, loam, friable or soluble materials, or organic matter; graded in accordance with ANSI/ASTM C136.

   G. Concrete: Structural concrete with a compressive strength of 2000 psi.

   2.02 Common Fill Materials

   A. Subsoil: Reused; or imported; excavated material free of gravel larger than 3 inch size, and debris.

   2.03 Accessories

   A. Soil Stabilization Fabric: A woven fabric composed of a stable network of polypropylene yarns. The fabric shall be inert to biological degradation and naturally encountered chemicals, alkalies, and acids. The fabric shall conform to the following minimum property values:

   1. Resistance to Installation and Damage:

   2. Grab Tensile Strength - 200 lb. - ASTM D1682-64.

   3. Grab Tensile Elongation - 35% - ASTM D1682-64.

   4. Burst Strength - 400 psi - ASTM D3786-80a.

   5. Trapezoidal Tear Strength - 110 lb. - ASTM D1117-80.

   6. Puncture Resistance - 70 lb. - ASTM D3787-80.

   7. Performance Criteria During Service Life:

   8. Modulus (load at 10% elongation) - 105 lb. - ASTM D1682-64.

   9. Coefficient or Permeability.001 cm/sec.

   PART 3 - EXECUTION

   3.01 Examination

   A. Verify fill materials to be reused are acceptable.

   B. Verify foundation perimeter drainage installation has been inspected.

   C. Verify underground tanks are anchored to their own foundation to avoid floatation after backfilling.

   3.2 Preparation

    A. Identify required lines, levels, contours, and datum.

   B. Generally, compact subgrade to density requirements for subsequent backfill materials.

   C. Cut out soft areas of subgrade not capable of insitu compaction. Backfill with Type B fill and compact to density equal to or greater than requirements for subsequent backfill material at the directions of Geotechnical Engineer.

   D. Prior to placement of aggregate base course material at paved areas, compact subsoil to 95 percent of its maximum dry density in accordance with ANSI/ASTM D1557.

   E. Protect plant life, lawn, rock outcropping and other features remaining as a portion of final landscaping.

   F. Protect bench marks, existing structures, fences, sidewalks, paving, and curbs from excavation equipment and vehicular traffic.

   G. Protect above and below grade utilities which are to remain.

   3.03 Excavation

   A. Excavation is Unclassified, and includes excavation to subgrade elevations indicated, regardless of character of materials and obstructions encountered. It shall be understood that any reference to rock, earth, or any other material on the drawings is not to be taken as an indication of classified excavation or the quantity of either rock, earth, or any other material involved.

   B. The bidder shall draw his own conclusions as to the conditions to be encountered.

   C. Underpin adjacent structures which may be damaged by excavation work, including utilities and pipe chases.

   D. Excavation cut shall not interfere with normal 45 degree bearing splay of foundation.

   E. Hand trim excavation and remove loose matter.

   F. Remove lumped subsoil, boulders, and rock up to 1/3  cu. yd. measured by volume.

   G. Notify Engineer of unexpected subsurface conditions and discontinue affected Work in area until notified to resume work.

   H. If unsuitable bearing materials are encountered at required subgrade elevations, carry excavations deeper and replace excavated material as directed by Engineer.

   1. Removal of unsuitable material and its replacement as directed will be paid on basis of contract conditions relative to changes in work.

   I. Unauthorized excavation consists of removal of materials beyond indicated subgrade elevations or dimensions without specific direction of Engineer. Unauthorized excavation, as well as remedial work directed by Engineer, shall be at Contractor's expense.

   1. Under footings, foundation bases, or retaining walls, fill unauthorized excavation by extending indicated bottom elevation of footing or base to excavation bottom, without altering required top elevation. Lean concrete fill may be used to bring elevations to proper position, when acceptable to Engineer.

   2. Elsewhere, backfill and compact unauthorized excavations as specified for authorized excavations of same classification, unless otherwise directed by Engineer.

   J. Stability of Excavations: Slope sides of excavations to comply with local codes and ordinances having jurisdiction. Shore and brace where sloping is not possible because of space restrictions or stability of material excavated.

   1. Maintain sides and slopes of excavations in safe condition until completion of backfilling.

   K. Dewatering: Prevent surface water and subsurface or ground water from flowing into excavations and from flooding project site and surrounding area.

   1. Do not allow water to accumulate in excavations. Remove water to prevent softening of subgrade foundation bottoms, undercutting footings, and soil changes detrimental to stability of subgrades and foundations. Provide and maintain pumps, well points, sumps, suction and discharge lines, and other dewatering system components necessary to convey water away from excavations.

   2. Establish and maintain temporary drainage ditches and other diversions outside excavation limits to convey rain water and water removed from excavations to collecting or run-off areas. Do not use trench excavations as temporary drainage ditches.

   L. Material Storage: Stockpile satisfactory excavated materials until required for backfill or fill. Place, grade and shape stockpiles for proper drainage.

   M. Locate and retain soil materials away from edge of excavations. Do not store within drip line of trees indicated to remain. 

   N. Dispose of excess soil material and waste materials as herein specified.

   O. Excavation for structures: Conform to elevations and dimensions shown within a tolerance of plus or minus 0.10', and extending a sufficient distance from footings and foundations to permit placing and removal of concrete formwork, installation of services, other construction, and for inspection.

   1. In excavating for footings and foundations, take care not to disturb bottom of excavation. Excavate by hand to final grade just before concrete reinforcement is placed. Trim bottoms to required lines and grades to leave solid base to receive other work.

   2. For pile foundations, stop excavations from 6" to 12" above bottom of footing before piles are placed. After piles have been driven, remove loose and displaced material, and excavate to final grade, leaving solid base to receive concrete pile caps.

   P. Excavation for Pavements: Cut surface under pavements to comply with cross-sections, elevations and grades as shown.

   Q. Excavation for Trenches: Dig trenches to the uniform width required for particular item to be installed, sufficiently wide to provide ample working room. Provide 6" to 9" clearance on both sides of pipe or conduit.

   1. Excavate trenches to depth indicated or required. Carry depth of trenches for piping to establish indicated flow lines and invert elevations. Beyond building perimeter, keep bottoms of trenches sufficiently below finish grade to avoid freeze-ups.

   2. Where rock is encountered, carry excavation 6" below required elevation and backfill with a 6" layer of crushed stone or gravel prior to installation of pipe.

   3. For pipes or conduit 5" or less in nominal size and for flat-bottomed multiple-duct conduit units, do not excavate beyond indicated depths. Hand excavate bottom cut to accurate elevations and support pipe or conduit on undistributed soil.

   4. For pipes or conduit 6" or larger in nominal size, tanks and other mechanical/electrical work indicated to receive subbase, excavate to subbase depth indicated or, if not otherwise indicated, to 6" below bottom of work to be supported.

   5. Except as otherwise indicated, excavate for exterior water-bearing piping (water, steam, condensate, drainage) so top of piping is not less than 1'-6" below finished grade.

   6. Grade bottoms of trenches as indicated, notching under pipe bells to provide solid bearing for entire body of pipe.

   3.04 Backfill and Fill

   A. General: Place acceptable soil material in layers to required subgrade elevations, for each area classification listed below.

   1. In excavations, use satisfactory excavated or borrow material.

   2. Under grassed areas, use satisfactory excavated or borrow material.

   3. Under walks, steps and pavements, use crushed stone.

   4. Under building slabs, use drainage fill material.

   5. Under piping and conduit, use bedding material where bedding is indicated under piping or conduit; shape to fit bottom 90 degrees of cylinder.

   B. Backfill trenches with concrete where trench excavations pass within 18" of column or wall footings and which are carried below bottom of such footings, or which pass under wall footings. Place concrete to level of bottom of adjacent footing. Backfill trenches within structure and paved areas with crushed stone.

   1. Do not backfill trenches until tests and inspections have been made and backfilling authorized by Engineer. Use care in backfilling to avoid damage or displacement of pipe systems.

   C. Backfill excavations as promptly as work permits, but not until completion of the following:

   1. Acceptance of construction below finish grade including, where applicable, dampproofing, waterproofing, and perimeter insulation.

   2. Inspection, testing, approval, and recording locations of underground utilities.

   3. Removal of concrete formwork.

   4. Removal of shoring and bracing, and backfilling of voids with satisfactory materials. Cut off temporary sheet piling driven below bottom of structures and remove in manner to prevent settlement of the structure or utilities, or leave in place if required.

   5. Removal of trash and debris.

   6. Permanent or temporary horizontal bracing is in place on horizontally supported walls.

   D. Ground Surface Preparation: Remove vegetation, debris, unsatisfactory soil materials, obstructions, and deleterious materials from ground surface prior to placement of fills. Plow, strip, or break-up sloped surfaces steeper than 1 vertical to 4 horizontal so that fill material will bond with existing surface. All areas shall be proofrolled at the direction of the Soils Engineer to determine soft areas.

   E. When existing ground surface has a density less than that specified under "Compaction" for particular area classification, break up ground surface, pulverize, moisture-condition to optimum moisture content, and compact to required depth and percentage of maximum density.

   F. Placement and Compaction: Place backfill and fill materials in layers not more than 8" in loose depth for material compacted by heavy compaction equipment, and not more than 4" in loose depth for material compacted by hand-operated tampers.

   G. Before compaction, moisten or aerate each layer as necessary to provide optimum moisture content. Compact each layer to required percentage of maximum dry density for each area classification. Do not place backfill or fill material on surfaces that are muddy, frozen, or contain frost or ice.

   H. Place backfill and fill materials evenly adjacent to structures, piping or conduit to required elevations. Take care to prevent wedging action of backfill against structures or displacement of piping or conduit by carrying material uniformly around structure, piping or conduit to approximately same elevation in each lift.

   I. Systematically backfill to allow maximum time for natural settlement. Do not backfill over porous, wet, frozen or spongy subgrade surfaces.

   J. Employ a placement method that does not disturb or damage foundation perimeter drainage, conduit duct in trench.

   K. Maintain optimum moisture content of backfill materials to attain required compaction density.

   L. Service renewal excavations in roadway shall be backfilled or steel plated within 24 hours of excavation.

   M. Service renewal excavations outside of roadway shall be backfilled within 7 days of excavation.

   N. Slope grade away from building minimum 6 inches in 10 ft. , unless noted otherwise.

   O. Make grade changes gradual. Blend slope into level areas.

   3.05 Compaction

   A. General: Control soil compaction during construction providing minimum percentage of density specified for each area classification indicated below.

   B. Percentage of Maximum Density Requirements: Compact soil to not less than the following percentages of maximum density for soils which exhibit a well-defined moisture density relationship (cohesive soils) determined in accordance with ASTM D 1557.

   1. Structures, Building Slabs and Steps, Pavements: Compact top 12" of subgrade and each layer of backfill or fill material at 95% maximum density.

   2. Lawn or Unpaved Areas: Compact top 6" of subgrade and each layer of backfill or fill material at 90% maximum density.

   3. Walkways: Compact top 6" of subgrade and each layer of backfill or fill material at 95% maximum density.

   C. Moisture Control: Where subgrade or layer of soil material must be moisture conditioned before compaction, uniformly apply water to surface of subgrade, or layer of soil material, to prevent free water appearing on surface during or subsequent to compaction operations.

   D. Remove and replace, or scarify and air dry, soil material that is too wet to permit compaction to specified density.

   E. Soil material that has been removed because it is too wet to permit compaction may be stockpiled or spread and allowed to dry. Assist drying by discing, harrowing or pulverizing until moisture content is reduced to a satisfactory value.

   3.06 Tolerances

   A. Top Surface of Backfilling: Under Paved Areas: Plus or minus one inch from required elevations.

   B. Top Surface of General Backfilling: Plus or minus one inch from required elevations.

   3.07 Field Quality Control

   A. Field inspection and testing will be performed under provisions of Section 01410 - Testing Laboratory Services.

   B. Tests and analysis of fill material will be performed in accordance with ANSI/ASTM D1557 and with Section 01410 - Testing Laboratory Services.

   C. Compaction testing will be performed in accordance with ANSI/ASTM D1557 and with Section 01410 - Testing Laboratory Services.

   D. If tests indicate Work does not meet specified requirements, remove Work, replace and retest at no cost to Owner.

   E. Quality Control Testing During Construction: Allow testing service to inspect and approve subgrades and fill layers before further construction work is performed.

   F. Footing Subgrade: For each strata of soil on which footings will be placed, conduct at least one test to verify required design bearing capacities. Subsequent verification and approval of each footing subgrade may be based on a visual comparison of each subgrade with related tested strata, when acceptable to Engineer.

   G. Paved Areas and Building Slab Subgrade: Make at least one field density test of subgrade for every 2000 sq. ft. of paved area or building slab, but in no case less than 3 tests. In each compacted fill layer, make one field density test for every 2000 sq. ft. of overlaying building slab or paved area, but in no case less than 3 tests.

   H. Foundation Wall Backfill: Take at least 2 field density tests, at locations and elevations as directed.

   3.08 Protection

   A. Protect excavations by methods required to prevent cave-in or loose soil from falling into excavation.

   B. Protect bottom of excavations and soil adjacent to and beneath foundation, from freezing.

   C. Protection of Graded Areas: Protect newly graded areas from traffic and erosion. Keep free of trash and debris. Provide temporary drainage swales or other structures to prevent ponding of water within construction limits.

   D. Repair and re-establish grades in settled, eroded, and rutted areas to specified tolerances.

   E. Reconditioning Compacted Areas: Where completed compacted areas are disturbed by subsequent construction operations or adverse weather, scarify surface, re-shape, and compact to required density prior to further construction.

   F. Settling: Where settling is measurable or observable at excavated areas during general project warranty period, remove surface (pavement, lawn or other finish), add backfill material, compact, and replace surface treatment. Restore appearance, quality, and condition of surface or finish to match adjacent work, and eliminate evidence of restoration to greatest extent possible.

   3.09 Disposal of Excess Waste Materials

   A. Removal from Owner's Property:

   1. Remove waste materials, including unacceptable excavated material, trash and debris, and dispose of it off Owner's property.

    END OF SECTION