SECTION 02200

EARTHWORK

PART 1. GENERAL

1.1	RELATED DOCUMENTS

A.	Drawings and general provisions of Contract apply to work of this Section.

1.2	SUMMARY

A.	This Section includes the following:

1.	Preparing of subgrade for building slabs, walks, and structures.

2.	For preparation of pavement subgrade.

3.	Excavating and backfilling of trenches within building lines.

4.	For pavement subgrade stabilization and base, refer to other Division 2 sections.

B.	Excavating and Backfilling of Utility Trenches: Refer to Earthwork - Underground Utilities, Section 02210.

C.	Final Grading, together with placement and preparation of topsoil for lawns and planting, is specified in Division 2 Section, "Landscape Work."

1.3	DEFINITIONS

A.	Excavation consists of removal of material encountered to subgrade elevations indicated and subsequent disposal of materials removed.

B.	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.	In locations other than those above, backfill and compact unauthorized excavations as specified for authorized excavations of same classification, unless otherwise directed by Engineer.

C.	Additional Excavation: When excavation has reached required subgrade elevations, notify Engineer, who will make an inspection of conditions. If Engineer determines that bearing materials at required subgrade elevations are unsuitable, continue excavation until suitable bearing materials are encountered and replace excavated material as directed by Engineer. The Contract Sum may be adjusted by an appropriate Contract Modification.

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

D.	Subgrade: The undisturbed earth or the compacted soil layer immediately below granular subbase, drainage fill, or topsoil materials.

E.	Structure: Buildings, foundations, slabs, tanks, curbs, or other man-made stationary features occurring above or below ground surface.

1.4	SUBMITTALS

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

1.	Test reports on borrow material.

2.	Verification of suitability of each footing subgrade material, in accordance with specified requirements.

3.	Field reports; in-place soil density tests.

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.

1.5	QUALITY ASSURANCE

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

B.	Testing and Inspection Service: Owner will employ and pay for a qualified independent geotechnical testing laboratory to perform soil testing and inspection service during earthwork operations.

C.	Testing Laboratory Qualifications: To qualify for acceptance, the geotechnical testing laboratory must demonstrate to Engineer's satisfaction, based on evaluation of laboratory-submitted criteria conforming to ASTM E 699, that it has the experience and capability to conduct required field and laboratory geotechnical testing without delaying the progress of the Work.

1.6	PROJECT CONDITIONS

A.	Site Information: Data in subsurface investigation reports was used for the basis of the design and are provided at the end of this specification section to the Contractor

for information only. Conditions are not intended as representations or warranties of accuracy or continuity between soil borings. The Owner will not be responsible for interpretations or conclusions drawn from this data by Contractor.

1.	Additional test borings and other exploratory operations may be performed by Contractor, at the Contractor's option; however, no change in the Contract Sum will be authorized for such additional exploration.

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

1.	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.

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

2.	Demolish and completely remove from site existing underground utilities indicated to be removed. Coordinate with utility companies and Owner for shutoff of services if lines are active.

C.	Use of Explosives: Use of explosives is not permitted.

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

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

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

3.	Perform excavation by hand within dripline of large trees to remain. Protect root systems from damage or dryout to the greatest extent possible. Maintain moist condition for root system and cover exposed roots with moistened burlap.

PART 2. PRODUCTS

2.1	SOIL MATERIALS

A.	Satisfactory soil materials are defined as those complying with ASTM D2487 soil classification groups GW, GP, GM, SM, SW, and SP.

B.	Unsatisfactory soil materials are defined as those complying with ASTM D2487 soil classification groups GC, SC, ML, MH, CL, CH, OL, OH, and PT.

C.	Backfill and Fill Materials: Satisfactory soil materials free of clay, rock or gravel larger than 2 inches in any dimension, debris, waste, frozen materials, vegetation and other deleterious matter.

PART 3. EXECUTION

3.1	EXCAVATION

A.	Excavation is unclassified and includes excavation to subgrade elevations indicated, regardless of character of materials and obstructions encountered.

3.2	STABILITY OF EXCAVATIONS

A.	General: Comply with local codes, ordinances, and requirements of agencies having jurisdiction.

B.	Slope sides of excavations to comply with local codes, ordinances, and requirements of agencies having jurisdiction. Shore and brace where sloping is not possible because of space restrictions or stability of material excavated. Maintain sides and slopes of excavations in safe condition until completion of backfilling.

C.	Shoring and Bracing: Provide materials for shoring and bracing, such as sheet piling, uprights, stringers, and cross braces, in good serviceable condition. Maintain shoring and bracing in excavations regardless of time period excavations will be open. Extend shoring and bracing as excavation progresses.

3.3	DEWATERING

A.	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 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 runoff areas. Do not use trench excavations as temporary drainage ditches.

3.4	STORAGE OF EXCAVATED MATERIALS

A.	Stockpile excavated materials acceptable for backfill and fill where directed. Place, grade, and shape stockpiles for proper drainage.

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

2.	Dispose of excess excavated soil material and materials not acceptable for use as backfill or fill.

3.5	EXCAVATION FOR STRUCTURES

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

1.	Excavations for footings and foundations: Do not 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.	Excavation for Underground Tanks, Basins, and Mechanical or Electrical Structures: Conform to elevations and dimensions indicated within a tolerance of plus or minus 0.10 foot; plus a sufficient distance to permit placing and removal of concrete formwork, installation of services, and other construction and for inspection. Do not disturb bottom of excavations, intended for bearing surface.

3.6	EXCAVATION FOR PAVEMENTS

A.	Cut surface under pavements to comply with cross-sections, elevations and grades as indicated.

3.7	TRENCH EXCAVATION FOR PIPES AND CONDUIT

A.	Refer to Earthwork - Underground Utilities, Section 02210.

3.8	COLD WEATHER PROTECTION

A.	Protect excavation bottoms against freezing when atmospheric temperature is less than 35 degrees F.

3.9	BACKFILL AND FILL

A.	General: Place soil material in layers to required subgrade elevations, for each area classification listed below, using materials specified in Part 2 of this Section.

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

2.	Under walks and pavements, use subbase material, satisfactory excavated or borrow material, or a combination.

3.	Under steps, use satisfactory excavated or borrow material.

4.	Under building slabs, use satisfactory excavated or borrow material.

5.	Backfill trenches with concrete where trench excavations pass within 18 inches of column or wall footings and that are carried below bottom of such footings or that pass under wall footings. Place concrete to level of bottom of adjacent footing.

a.	Concrete is specified in Division 3.

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

6.	Provide 4-inch-thick concrete base slab support for piping or conduit less than 2'-6" below surface of roadways. After installation and testing of piping or conduit, provide minimum 4-inch-thick encasement (sides and top) of concrete prior to backfilling or placement of roadway subbase.

B.	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 have been performed and recorded.

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 from excavation.

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

3.10	PLACEMENT AND COMPACTION

A.	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.

1.	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.

B.	Place backfill and fill materials in layers not more than 8 inches in loose depth for material compacted by heavy compaction equipment, and not more than 4 inches in loose depth for material compacted by hand-operated tampers.

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

D.	Place backfill and fill materials evenly adjacent to structures, piping, or conduit to required elevations. 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.

E.	Control soil and fill compaction, providing minimum percentage of density specified for each area classification indicated below. Correct improperly compacted areas or lifts as directed by Engineer if soil density tests indicate inadequate compaction.

1.	Percentage of Maximum Density Requirements: Compact soil to not less than the following percentages of maximum density, in accordance with ASTM D 1557:

a.	Under structures, building slabs and steps, and pavements, compact top 12 inches of subgrade and each layer of backfill or fill material at 98 percent maximum density.

b.	Under lawn or unpaved areas, compact top 6 inches of subgrade and each layer of backfill or fill material at 90 percent maximum density.

c.	Under walkways, compact top 6 inches of subgrade and each layer of backfill or fill material at 95 percent maximum density.

2.	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. Apply water in minimum quantity as necessary to prevent free water from appearing on surface during or subsequent to compaction operations.

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

b.	Stockpile or spread soil material that has been removed because it is too wet to permit compaction. Assist drying by discing, harrowing, or pulverizing until moisture content is reduced to a satisfactory value.

3.11	GRADING

A.	General: Uniformly grade areas within limits of grading under this section, including adjacent transition areas. Smooth finished surface within specified tolerances, compact with uniform levels or slopes between points where elevations are indicated or between such points and existing grades.

B.	Grading Outside Building Lines: Grade areas adjacent to building lines to drain away from structures and to prevent ponding. Finish surfaces free from irregular surface changes and as follows:

1.	Lawn or Unpaved Areas: Finish areas to receive topsoil to within not more than 0.10 foot above or below required subgrade elevations.

2.	Walks: Shape surface of areas under walks to line, grade, and cross-section, with finish surface not more than 0.10 foot above or below required subgrade elevation.

3.	Pavements: Shape surface of areas under pavement to line, grade, and cross-section, with finish surface not more than 1/2 inch above or below required subgrade elevation.

C.	Grading Surface of Fill under Building Slabs: Grade smooth and even, free of voids, compacted as specified, and to required elevation. Provide final grades within a tolerance of 1/2 inch when tested with a 10-foot straightedge.

D.	Compaction: After grading, compact subgrade surfaces to the depth and indicated percentage of maximum or relative density for each area classification.

3.12	PAVEMENT SUBBASE COURSE

A.	Refer to other Division 2 sections for preparation of subgrade, subbase, base, and paving specifications.

B.	Grade Control: During construction, maintain lines and grades including crown and cross-slope of subbase course.

3.13	FIELD QUALITY CONTROL

A.	Quality Control Testing During Construction: Allow testing service to inspect and approve each subgrade and fill layer before further backfill or construction work is performed.

1.	Perform field density tests in accordance with ASTM D 1556 (sand cone method) or AASHTO T-180 or ASTM D 2167 (rubber balloon method), as applicable.

a.	Field density tests may also be performed by the nuclear method in accordance with ASTM D 2922, providing that calibration curves are periodically checked and adjusted to correlate to tests performed using ASTM D 1556. In conjunction with each density calibration check, check the calibration curves furnished with the moisture gages in accordance with ASTM D 3017.

b.	If field tests are performed using nuclear methods, make calibration checks of both density and moisture gages at beginning of work, on each different type of material encountered, and at intervals as directed by the Engineer.

2.	Footing Subgrade: For each strata of soil on which footings will be placed, perform 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.

3.	Building Slab Subgrade: Perform at least one field density test of subgrade for every 2,000 sq. ft. of paved area or building slab, but in no case fewer than three tests. In each compacted fill layer, perform one field density test for every 2,000 sq. ft. of overlaying building slab or paved area, but in no case fewer than three tests.

4.	Foundation Wall Backfill: Perform at least two field density tests at locations and elevations as directed.

5.	Pavement Subgrade: One field density test for each compacted layer per 10,000 sq. ft. of paved area or 250 l.f. of roadways, but no fewer than three tests per paved area.

6.	If in opinion of Engineer, based on testing service reports and inspection, subgrade or fills that have been placed are below specified density, perform additional compaction and testing until specified density is obtained.

3.14	EROSION CONTROL

A.	Provide erosion control methods in accordance with requirements of authorities having jurisdiction.

3.15	MAINTENANCE

A.	Protection of Graded Areas: Protect newly graded areas from traffic and erosion. Keep free of trash and debris.

B.	Repair and reestablish grades in settled, eroded, and rutted areas to specified tolerances.

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

D.	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.

3.16	DISPOSAL OF EXCESS AND WASTE MATERIALS

A.	Removal from Owner's Property: Remove waste materials, including unacceptable excavated material, trash, and debris, and dispose of it off Owner's property.

END OF SECTION