g.02220_-_Excvation ABC.doc

SECTION 02220

EXCAVATION, BACKFILL, AND EMBANKMENT

SEQ CHAPTER \h \r 1PART 1 - GENERAL

1.1

DESCRIPTION

A.

This section includes, but is not necessarily limited to, all excavation, embankment, backfill, borrow, granular leveling course, aggregate base course and all rough and finish grading for:

1.

Reinforced Concrete Helipad and Landing.

2.

Exterior (sidewalk) floor slabs.

1.2

RELATED WORK

Submittals: According to Section 01009 - General Requirements.

B.

Section 03306 - Minor Concrete 1.3

SUBMITTALS

The following submittals for construction shall be made in accordance with the project submittal requirements.

Moisture Density (Proctor) Results (AASHTO T-99), gradation, and material source for aggregate base course, additional backfill/borrow material, and materials used for backfill. No gradation is required for excavated material used as backfill.

1.4

GENERAL REQUIREMENTS

Excavation work shall be performed in a safe and proper manner with appropriate precautions taken against all hazards. Excavation shall provide adequate working space and clearances for the work to be performed therein and for installation and removal of concrete forms.

B.

Aggregate base course surfaces shall be clean and free of loose material of any kind when concrete is placed thereon.

C.

Backfilling and construction of fills and embankments during freezing weather shall not be done except by permission of the Contracting Officer. No backfill, fill or embankment materials shall be installed on frozen surfaces, nor shall frozen materials, snow or ice be placed in any backfill, fill or embankment.

D.

All excavation shall be considered unclassified. Unclassified Excavation includes all costs associated with excavation and backfill including compaction to contract specifications.

E.

Excess Material: Usable excess material excavated shall be used in the embankment construction before the use of borrow is allowed. Borrow wasting is not permitted.

F.

Borrow Material Source: If needed, obtain additional embankment/borrow material from an outside source that meets the requirements of the Fill and Embankment Material Sub-section. Borrow material shall not be obtained from the construction site.

G.

All excavation, backfills, fills and embankment shall be protected from damage from rain and equipment operations. All structures, fences, and other objects not designated for removal shall be protected from damage at all times.

H.

Compaction, when referred to as a percentage, shall mean the percentage of maximum laboratory density as determined by AASHTO T-99.

I. All excavation shall be constructed in accordance with OSHA standards.

PART 2

PRODUCTS

2.1

MATERIALS

A.

FILL AND EMBANKMENT MATERIAL

1.

All fill and embankment material shall be free of frost and ice, organic material, rocks or lumps larger than 6 inches, and other deleterious materials. All material shall have uniform consistency in the entire fill or embankment and shall have a maximum plasticity index of 8, unless otherwise specified herein.

B.

AGGREGATE BASE COURSE

Aggregate base course material under slabs and sidewalks shall be free draining clean crushed mineral aggregate with the following gradation of and 3/4" minus material:

Table of Gradations

Percentages Passing by Weight Passing Square Mesh Screens

½ inch

PART 3

EXECUTION

3.1

GENERAL

No work performed or installed shall be covered or enclosed by backfill or embankment until all required inspections, tests, and approvals have been completed. Any such work so enclosed or covered before it has been approved shall be uncovered at no additional cost to the Government.

B.

Prepare all areas to be excavated in accordance with the Site Preparation subsection.

Survey Markers and Monuments. The Contractor shall use every care and precaution to protect and not disturb survey markers or monuments such as those that might be located at lot or block corners, property pins, the intersection of street monuments or additional line demarcations. No monuments shall be disturbed without prior approval of the Contracting Officer. Any survey marker or monument that is disturbed or destroyed by the Contractor without approval during the construction of this project shall be replaced at no cost to the Government by a licensed land surveyor.

D. During excavation, materials suitable for backfilling shall be piled in an orderly manner a sufficient distance from the banks of the excavation to avoid overloading and to prevent slides or cave-ins. Minimize disturbed areas with placement of excavated spoils. Excavated material from trenches shall be piled on one side of the trench only. Place excavation spoils so surface drainage of areas adjoining excavations are not unobstructed.

3.2

SITE PREPARATION

A. Clearing and Grubbing: The area to be excavated, and the surface area to be covered by fill material, shall be thoroughly cleared and stripped of topsoil. Dispose of brush, trees, stumps, roots, loose rocks, and other objectionable materials at contractors expense.

B. No separate measurement and payment for this work is included in the contract. Include this work in the lump sum contract price for Project Site Preparation.

3.3

EXCAVATION

A. Perform excavation to the lines, grades, and elevations indicated on the drawings and as staked in the field to allow for safety, placing and inspection. Provide proper depth with allowance made for crushed aggregate base bedding. Keep all excavations dry.

Where indicated on the Drawings, or directed by the Contracting Officer in the field, sub-excavation shall be performed to greater depth to remove unstable or unsuitable soil materials. Sub-excavation and subsequent backfill with suitable material will not be measured and paid separately. Include this work in the lump sum contract price for Project Site Preparation.

3.4

PREPARATION OF SUBGRADE

Excavated subgrades under fills and embankments shall be leveled, kept dry or only watered as necessary to achieve optimum moisture content, and compacted with mechanical plate tampers or vibrating compacting equipment.

All deleterious material in the subgrade shall be removed to the extent determined by the Contracting Officer and replaced with suitable embankment material and compacted as specified above.

Subgrades shall be protected from excessive moisture until footings or fill material are in place. Any subgrade saturated by rain or flooding shall be sub-excavated and backfilled (at the Contractor's expense).

D.

Subgrades shall be finished to plus or minus 0.05-feet of grade. Compact general sub-grades to a minimum of 95% of Standard Proctor.

3.5

BACKFILL AND EMBANKMENT

A. Backfill and embankment shall be placed in thin uniform lifts not exceeding 6-inch in compacted thickness, watered to achieve optimum moisture content, and compacted to 95% of Standard Proctor (AASHTO T-99) maximum dry density.

Backfill and embankment shall be finished to plus or minus 0.05-feet of grade under slabs.

MALHEUR NATIONAL FOREST NOTE: CONTRACTOR SHALL COMPACT REGRADED SECTIONS OUTSIDE OF HELIPADS BY ADJUSTING THE MOISTURE CONTENT OF THE BACKFILL MATERIAL TO A MOISTURE CONTENT SUITABLE FOR COMPACTION. CONTRACTOR SHALL COMPACT EACH 6 INCH (MAXIMUM DEPTH) LAYER WITH A MINIMUM OF THREE COMPLETE PASSES UNTIL THERE IS NO VISIBLE EVIDENCE OF FURTHER CONSOLIDATION. ALL COMPACTION EQUIPMENT SHALL RECEIVE APPROVAL FROM CO OR DESIGNATED REPRESENTATIVE BEFORE COMMENCING COMPACTION.

Any damage to the concrete structures or sidewalk by the Contractor during backfilling and finishing operations shall be repaired or replaced at no additional cost to the Government.

3.6

AGGREGATE BASE COURSE

A. Aggregate base course shall be installed in a 4-inch lift plus or minus 0.5-inch under all slabs on grade including sidewalks.

3.7

UNIFORMITY OF BACKFILL AND EMBANKMENT

All backfill and embankment material shall be selectively placed to provide a uniform consistency of material throughout the fill.

B. A uniform moisture content shall be maintained at optimum (plus or minus 2%) throughout the fill to achieve maximum and uniform compaction.

All soft, spongy areas shall be excavated and the unstable material shall be replaced with suitable material and compacted as required.

3.8

TESTING AND INSPECTION

Testing shall be conducted in the presence of the Contracting Officer Representative who shall be given 48-hours notice before any test is to be conducted. Make arrangements for a certified, independent testing laboratory to perform the moisture density testing of backfill and aggregate base to substantiate each days work. Record and distribute the results.

B. All backfill and embankments will be subject to random inspection and testing. No further work shall proceed until all tests and inspections have been satisfactorily completed and approval has been given to proceed. Access to the work shall be given when requested.

Should any test fail to meet the specifications, the Contractor shall recompact the failed areas and pay for all retests.

D.

Random field compaction tests which are performed by the Contracting Officer do not relieve the Contractor of his responsibility to achieve the specified level of compaction on all portions of the Project.

3.9

FINAL GRADING

A.

Upon completion of excavation and backfilling, rough grade all disturbed areas, and fine grade.

B. There is aggregate material adjacent to the building and in the projected excavation area for the pad. Salvage this material and stockpile. Replace this material as the final grading material. Start replacing this material directly adjacent to the finished concrete pads to ensure there are no drop-offs. Replace on 10:1 slopes. Include this work in the contract price for Project Site Preparation.

MALHEUR NATIONAL FOREST NOTE: CONTRACTOR SHALL BE RESPONSIBLE FOR FURNISHING ALL NEEDED AGGREGATE TO ADEQUATELY ROCK ALL REGRADED SECTIONS AWAY FROM HELIPADS AND TRANSITIONS. REGRADING AWAY FROM HELIPADS SHALL BE DONE AT A 5% SLOPE UNLESS OTHERWISE APPROVED BY CO OR DESIGNATED REPRESENTATIVE.

C. Grade areas adjacent to concrete pads and sidewalks to drain away from structures to prevent ponding. Blend disturbed area grades with existing undisturbed contours. Excess backfill may be graded in place of construction in disturbed areas.

PART 4: MEASUREMENT AND PAYMENT

4.1

METHOD OF MEASUREMENT

A. Units: All work associated with the excavation, compaction, and additional embankment/borrow material placed and compacted will be measured and paid at the lump sum contract price for Project Site Preparation. Include the cost of all grade work associated with the preparation and finishing of the site in the lump sum contract price for Project Site Preparation also. No adjustments for shrink or swell will be paid. No separate payment will be made for removing water by aeration of fill material to obtain the required density, or material used for purposes other than specified or authorized, or fill material scarified in place and utilized by mixing or similar operations. No separate payment will be made for transporting excavated material from the excavation to the fill or waste area.

B. Units: Aggregate Base Course will be measured and paid for by plan neat lines from the specifications and drawings. No additional quantity will be paid for Aggregate Base Course placement beyond the lines and grades shown on the drawings or specifications.

4.2

BASIS OF PAYMENT

A.

Payment: Prices and payment will be full compensation for the work described in this section. Payment will be made under:

Pay Item

Pay Unit 02220(01) Project Site Preparation

Lump Sum 02220(02) Aggregate Base Course

Cubic Yard

END OF SECTION 02220

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