B09_AMEND_02_Attach_(5)_31_20_00_-_Earth_Moving_MORA_Ohana_AMEND02_0002.pdf

MORA 313019 / 331809 / 312439 31 20 00 - 1

EARTH MOVING

SECTION 31 20 00 – EARTH MOVING

PART 1 - GENERAL

1.1 RELATED DOCUMENTS

A. Drawings and general provisions of the Contract, including General and Supplementary

Conditions and Division 01 Specification Sections, apply to this Section.

1.2 SUMMARY

A. This Section includes the following:

1. Preparing subgrades for parking areas, walkways, and graded compacted soil areas.

2. Subbase course for walks.

3. Subbase and base course for asphalt paving.

4. Excavating and backfilling for utility trenches.

5. Reuse of native soils.

6. Site grading and earthwork for graded compacted soil areas.

B. Related Sections include the following:

1. Section 01 57 23 – Temporary Stormwater Pollution Prevention

2. Section 31 10 00 – Site Clearing

3. Section 31 25 00 – Erosion and Sediment Control

4. Section 32 13 20 – Site Concrete

5. Section 32 12 16 – Asphalt Paving

1.3 DEFINITIONS

A. Backfill: Soil material or controlled low-strength material used to fill an excavation.

1. Initial Backfill: Backfill placed beside and over pipe in a trench, including haunches to support sides of pipe.

2. Final Backfill: Backfill placed over initial backfill to fill a trench.

B. Base Course: The layer or layers of specified material placed on a subbase or subgrade to support a surface course.

C. Borrow Soil: Satisfactory soil imported from off-site for use as fill or backfill.

D. Earth Grade: The elevation of the completely graded roadway before placing the pavement structure.

E. Excavation: Removal of material encountered above subgrade elevations and to lines and dimensions indicated.

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1. Unauthorized Excavation: Excavation below subgrade elevations or beyond indicated lines and dimensions without direction by CO. Unauthorized excavation, as well as remedial work directed by CO, shall be without additional compensation.

F. Fill: Soil materials used to raise existing grades.

G. Pavement Structure: All combinations of subbase, base course, and surface course, including shoulders, placed on a subgrade.

H. Rock: Rock material in beds, ledges, unstratified masses, conglomerate deposits, and boulders of rock material 3/4 cu. yd. (0.57 cu. m) or more in volume that exceed a standard penetration resistance of 100 blows/2 inches (97 blows/50 mm) when tested by an independent geotechnical testing agency, according to ASTM D 1586.

I. Structures: Buildings, footings, foundations, retaining walls, curbs, or other man-made stationary features constructed above or below the ground surface.

J. Subbase Course: The layer of specified material placed on the subgrade as a part of the pavement structure.

K. Subgrade: The portion of the earth grade upon which the pavement structure is placed.

L. Utilities: On-site underground pipes, conduits, ducts, and cables.

M. Earthwork Terminology: Terms used in this Section and not defined herein shall be interpreted in accordance with the definitions given in ASTM D653.

N. Embankment: Soil or soil-rock material placed to raise the subgrade or natural grade of the site for embankment construction.

O. Native Soil: Sand or silt naturally occurring on site that was never imported to the site, is weed free, and supports local native habitats.

P. Unsuitable Material: Excavated material or material below the natural ground surface in embankment areas or below subgrade elevation in excavated areas, which is unsuitable for its planned use as determined by the Contracting Officer. Unsuitable material is further defined as material determined to be:

1. Of such unstable nature as to be incapable of being compacted to specified density using ordinary methods at optimum moisture content.

2. Too wet to be properly compacted and circumstances prevent suitable in-place drying prior to incorporation into the Work.

3. Not meeting requirements specified in Part 2 of this Section.

4. Otherwise unsuitable for the planned use.

The presence of excessive moisture in a material is not, by itself, sufficient cause for determining that the material is unsuitable.

Q. Relative Compaction: The ratio, expressed as a percentage, of the in-place dry density of fill materials as compacted in the field to the maximum dry density of the same material.

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R. Optimum Moisture Content: The water content at which a soil can be compacted to a maximum dry unit weight by a given compactive effort.

1.4 LAWS AND REGULATIONS

A. Work shall be accomplished in accordance with regulations of local, township, county, state and federal agencies or utility company standards as they apply.

1.5 SUBMITTALS

A. Delivery Tickets: Submit a delivery ticket with each load of imported material delivered to the site, stating the type of fill material, source, and the quantity.

B. Product Data, including weed free certification: For the following:

1. All aggregates proposed for use.

2. Import fill.

3. Geotextile / Fabric

C. Material Test Reports: The Contractor shall conduct testing at their own expense for material testing of material that does not come from a pre-approved quarry. The test information shall be provided to the CO for approval prior to material import. Material test reports shall be from a qualified testing agency indicating and interpreting test results for compliance of the following with requirements indicated:

1. Classification according to ASTM D 2487 of each on-site and import soil material proposed for fill and backfill.

2. Laboratory compaction curve according to ASTM D 1557 for each on-site and import soil material proposed for fill and backfill.

D. Pre-excavation Photographs or Videotape: Show existing conditions of adjoining construction and site improvements, including finish surfaces, that might be misconstrued as damage caused by earthwork operations. Submit before earthwork begins.

1.6 QUALITY ASSURANCE

A. Pre-excavation Conference: Conduct conference at Project site to comply with requirements in

Division 01 Section “Project Management and Coordination.”

B. Tolerances:

1. Construct finished subgrades to plus 0 or minus 1/2-inch of the elevations indicated.

2. Construct finished grade of slopes not steeper than 4:1 or 3:1 minus where noted and on slopes steeper than 4:1 plus or minus two inches (2").

3. Maintain the moisture content of fill material as it is being placed within plus or minus 2% of the optimum moisture content of the material as determined by the laboratory tests herein specified.

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1.7 PROJECT CONDITIONS

A. Unfavorable Weather Conditions:

1. Excavating, filling, backfilling, and grading work shall not be performed during weather conditions that might damage or be detrimental to the condition of existing ground, in-progress work, or completed work. When the Work is interrupted by rain, freezing weather, or other conditions deemed unsuitable by the CO, excavating, filling, backfilling, and grading work shall not resume until the site and soil condition (moisture content) are suitable for compaction.

2. Subgrade shall be free from mud, snow, ice, and deleterious material when work is resumed.

3. Soil material that is too wet for compaction shall be left to drain, to be aerated and dried by disking and harrowing or other approved method until the moisture content of the area is uniform and within the specified limits.

B. Erosion Prevention: Protect stockpiles, ditches, embankments, filled, backfilled, and graded areas to prevent erosion until such time as permanent drainage and erosion control measures have been installed per the requirements of Section 01 57 23 – Temporary Storm Water Pollution

Prevention.

C. Control of Dust: Employ construction methods and means that keep flying dust to the minimum throughout the entire Contract period. It may include watering and sprinkling, or other approved methods at the construction site of such frequency that will satisfactorily control the dust caused by construction operations.

D. Control of Dirt: Promptly remove from existing roadways all dirt and other materials that have been spilled, washed, tracked, or otherwise deposited thereon by construction operations whenever the accumulation is sufficient to cause the formation of mud, interfere with drainage, damage pavements, or create a traffic hazard.

E. Indicated locations of existing facilities and systems are approximate. Investigate and determine exact location and nature of utilities, facilities, and systems, and be solely responsible for damages caused by construction activities.

F. Excavation in areas that have or may have underground facilities:

1. Delineate with white paint, flags, or other methods the area to be excavated and contact

Underground Location Service to request that facility owners mark the location of underground utilities.

2. Identify temporary survey markings using PINK colored markings in accordance with

Underground Service alert requirements.

3. Facility owners will field mark approximate location and number of subsurface installations affected by excavation using the following colors:

a. Safety RED – Electric power, distribution, and transmission installations, or municipal electric installations.

b. High Visibility Safety YELLOW – Gas distribution and transmission installations, oil distribution and transmission installations containing or transporting dangerous materials, products, or steam.

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c. Safety Alert ORANGE – Telephone and telegraph installations, police and fire communication installations, and cable television installations.

d. Safety Precaution BLUE – Water installations and slurry pipelines.

e. Safety GREEN – Sewer installations.

f. Do not use above listed colors for Contractor’s temporary markings suck as survey points; use U.S.A. designated PINK color.

PART 2 - PRODUCTS

2.1 GENERAL

A. All material sources and materials incorporated into the work must be certified to be free from noxious weeds, invasive plants, and other deleterious materials by a federal, state or local public agency and approved by NPS. Commercial certifications may be acceptable if materials have been certified through the North American Weed Free Forage Program standard or a similarly recognized certification process approved by the CO. When applicable, submit material certifications to the CO for approval at least 7 days before their use in the work. Sources should be from the approved list or submitted in time, per subsection 2.1.B.2. below. Any external reports may be rejected if:

1. Do not meet MORA weed free standards (active weed control programs, fresh fill, no novel weeds to the area or park) or

2. Do not contain enough information to assess the above.

All material sources are subject to annual inspections and approvals for use each year. Material obtained from certified weed free sources are to be transported directly to the project or staging area limits without stockpiling at another site.

B. When obtaining any mined fill material from the following sources, mine from locations in the source pit that have the least potential to harbor weed seed or propagules. Remove 3 feet deep of overburden before mining new material. Do not use materials from stockpiles that have been in place over a growing season or show signs of weed infestation.

1. 2024 material certifications for the following sources are not required because these sources have been deemed weed free certified for construction in 2024.

a. Randles Sand & Gravel Inc.

5802 192nd Street E

Puyallup, WA 98375

(253) 531-6835

b. Ashe Quarry

1203 Falls Road

Randle, WA 98377

(360) 520-4375

c. Cal-Portland DuPont

4301 Pioneer Way

DuPont, WA 98327

(206) 406-0397

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2. If sources excluding those listed under Subsection 2.1.B.1. are utilized for construction year 2024, notify the CO of the intended material sources to be utilized at least 60 days in advance and by July 1, 2024.

3. By July 1 of each year, notify the CO of the intended material sources to be utilized in the following construction year. This includes the sources listed under Subsection 2.1.B.1.

C. All imported soil and aggregates shall be trash free.

2.2 TRENCH EXCAVATION NATIVE MATERIAL

A. Native material excavated for trenches shall not be anticipated to be used as trench backfill except in wetland areas where existing pipes and structures are only removed. Excavated native material shall be tested to verify conformance with requirements for trench backfill.

2.3 ENGINEERED FILL MATERIALS

A. Material reports shall be provided verifying quarry source of materials.

B. Imported soil for use as engineered fill should have 35 or less percent passing the No. 200 sieve, a low swell potential (approximately 1-percent or less when wetted against a surcharge pressure of 200 psf), and a low plasticity index (approximately 15 or less). Imported soil should not contain organic matter, clay lumps, bedrock (shale, claystone, sandstone, etc.) fragments, debris, other deleterious matter, or particles larger than approximately 3 inches nominal diameter. Imported soil for use as engineered fill should exhibit low corrosion potential. Imported soil placed in contact with ferrous materials should have a saturated soil resistivity of 2,000 ohm-cm or more and a chloride content of 25 parts per million or less. Soils in contact with concrete should exhibit soluble sulfate content less than 0.1 percent.

C. Site soils generated from on-site excavation activities of fill and residuum shall not be anticipated to be used as engineering fill. Additional evaluation and laboratory testing should be performed by the contractor during earthwork activities to better evaluate the suitability of the on-site soils for re-use as engineered fill at this site.

D. Excavated material that is suitable for fill, backfill, and embankment construction shall be conditioned for reuse. Rocks exceeding three inches (3") in largest dimension and deleterious material shall be removed from the site and disposed of as specified herein.

2.4 SOIL MATERIALS

A. Embankment: All embankment material shall consist of clean well-graded soil with little or no potential for expansion.

B. Crushed Surfacing: Crushed surfacing shall be manufactured from ledge rock, talus, or gravel.

The materials shall be uniform in quality and substantially free from wood, roots, bark, and other extraneous material and shall meet the following quality test requirements:

1. Los Angeles Wear, 500 Rev. 35 percent max.

2. Degradation Factor – Top Course 25 min.

3. Degradation Factor – Base Course 15 min.

kevin.kraxberger Cloud

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Crushed surfacing of the various classes shall meet the applicable requirements for grading and quality when placed in hauling vehicles for delivery to the roadway, or during manufacture and placement into a temporary stockpile.

The fracture requirement shall be at least one fractured face and will apply to the combined aggregate retained on the No. 4 sieve in accordance with FOP for AASHTO T 335.

The portion of crushed surfacing retained on a No. 4 sieve shall not contain more than 0.15 percent wood waste.

C. Crushed Surfacing Base Course: Material complying with Crushed Surfacing definition and the following gradation:

Sieve Size Base Course

Percent Passing

1 ¼” 99-100

1” 80-100

5/8” 50-80

No. 4 25-45

No. 40 3-18

No. 200 5.0 max.

% Fracture 75 min.

Sand Equivalent 40 min.

D. Crushed Surfacing Top Course

1. Crushed surfacing shall be manufactured from ledge rock, talus, or gravel. The materials shall be uniform in quality and substantially free from wood, roots, bark, and other extraneous material and shall meet the following quality test requirements:

Los Angeles Wear, 500 Rev. 35 percent max.

Degradation Factor – Top Course 25 min.

Degradation Factor – Base Course 15 min.

Crushed surfacing of the various classes shall meet the following requirements for grading and quality when placed in hauling vehicles for delivery to the roadway, or during manufacture and placement into a temporary stockpile.

Sieve Size Percent Passing

3/4” 99-100

1/2” 80-100

No. 4 46-66

No. 40 8-24

No. 200 10.0 max.

% Fracture 75 min.

Sand Equivalent 40 min.

All percentages are by weight

2. The fracture requirement shall be at least one fractured face and will apply to the combined aggregate retained on the No. 4 sieve in accordance with field operating procedures for

AASHTO T 335.

3. The portion of crushed surfacing retained on a No. 4 sieve shall not contain more than 0.15 percent wood waste.

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E. Gravel Backfill for Walls: Material shall consist of free draining granular material, essentially free from various types of wood waste or other extraneous or objectionable materials. It shall meet the following requirements for grading and quality when placed in hauling vehicles for delivery to the roadway or during manufacture and placement into a temporary stockpile.

Sieve Size Percent Passing

4” 99-100

2” 75-100

No. 4 22-66

No. 200 5.0 max.

Dust Ratio: %

Passing No. 200 /

% Passing No. 40

2/3 max.

Sand Equivalent 60 min.

That portion of the material retained on a No. 4 sieve shall contain not more than 0.20 percent by weight of wood waste.

F. Gravel Borrow: Aggregate for gravel borrow shall consist of granular material, either naturally occurring or processed, and shall meet the following requirements for grading and quality:

Sieve Size Percent Passing

4” 99-100

2” 75-100

No. 4 50-80

No. 40 30 max.

No. 200 7.0 max.

Sand Equivalent 50 min.

G. Gravel Backfill for Pipe Zone Bedding

1. Gravel backfill for pipe zone bedding shall consist of crushed, processed, or naturally occurring granular material. It shall be free from various types of wood waste or other extraneous or objectionable materials. It shall have such characteristics of size and shape that it will compact and shall meet the following requirements for grading and quality:

Sieve Size Percent Passing

1 1/2” 99-100

1” 75-100

3/8” 50-100

No. 4 20-80

No. 40 3-24

No. 200 10.0 max.

Sand Equivalent 35 min.

All percentages are by weight

2. If the native granular material is free from wood waste, organic material, and other extraneous or objectionable materials, but otherwise does not conform to the requirements for grading and Sand Equivalent, it may be used for pipe bedding for rigid pipes, provided the native granular material has a maximum dimension if 1½ inches.

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H. Structural Fill Material: See Section 2.1.B and Section 2.1.C.

I. Sand: ASTM C 33; fine aggregate, natural, or manufactured.

J. Quarry spalls: Quarry spalls shall meet the following requirements for grading:

Sieve Size Percent Passing

8” 100

3” 40 max.

¾” 10 max.

K. Controlled Low Strength Material (CLSM): Fluid, workable mixture of aggregate, Portland cement, and water. The 28-day strength of the material should be no less than 50 pounds per square inch (psi) and no more than 150 psi.

L. Geotextile: Geotextile material complying with the requirements of the following table:

Geotextile Property ASTM

Test

Method

Geotextile Property Requirements

Separation Soil Separation

Woven Nonwoven Woven Nonwoven

AOS D4751 No. 30 max. No. 40 max.

Water Permittivity D4491 0.02 sec-1 min. 0.10sec-1 min.

Grab Tensile Strength, in machine and x-machine direction

D4632 250 lb min. 160 lb min. 315 lb min. 200 lb min.

Grab Failure Strain, in machine and x-machine direction

D4632 < 50% >50% < 50% >50%

Seam Breaking Strength D4632 220 lb min. 140 lb min. 270 lb min. 180 lb min.

Puncture Resistance D6241 495 lb min. 310 lb min. 620 lb min. 430 lb min.

Tear Strength, in machine and x-machine direction

D4533 80 lb min. 50 lb min. 112 lb min. 79 lb min.

Ultraviolet (UV) Radiation

Stability

D4355 50% strength retained min., after 500 hours in xenon arc device

M. Rock Slope Protection Fabric

1. RSP fabric must be a permeable, nonwoven, needle-punched geotextile. The fabric must be manufactured from one of the following:

a. Polyester

b. Polypropylene

c. Combined polyester and polypropylene

2. Polymers must be either virgin compounds or clean reworked material. Do not subject virgin compounds to use or processing other than required for initial manufacture. Clean reworked material must be previously processed material from the processor's own production that has been reground, pelletized, or solvated. The fabric must not contain more than 20 percent of clean reworked material by weight. Do not use recycled materials from either post-consumer or post-industrial sources.

3. Rock slope protection fabric must comply with the requirements of the following table:

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Quality Characteristic Test Method Requirement

Mass, (min, oz/sq yd) ASTM D5261 7.5

Grab breaking load, I inch grip in each direction, (min, lb) ASTM D4632 200

Apparent elongation in each direction, (min, percent) ASTM D4632 50

Permittivity, (min, sec-1) ASTM D4491 1.0

Apparent opening size, (min and max, US Standard sieve size)

ASTM D4751 70-100

UV resistance, retained grab breaking load, 500 hours, (min, percent)

ASTM D4355 70

N. On-Site Topsoil: The top four-inches (4”) minimum of organic material in excavation zones shall be stripped stockpiled prior to other earthwork operations. All stockpiled topsoil shall be reused on site unless otherwise noted.

PART 3 - EXECUTION

3.1 PREPARATION

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

B. Preparation of subgrade for earthwork operations including removal of vegetation, topsoil, debris, and obstructions, from ground surface is specified in Section 31 10 00 Site Clearing.

C. Provide erosion-control measures to prevent erosion or displacement of soils and discharge of soil-bearing water runoff or airborne dust.

3.2 STAKING AND GRADES

A. Layout the work, establish all necessary markers, benchmarks, grading stakes, and other stakes as required, in accordance with the lines and grades of the Plans.

3.3 UTILITIES

A. Verify on site the location and depth (elevation) of all existing utilities and services before performing any excavation work. Use the 811 call utility service and other means required to verify locations.

B. Active utility lines encountered, which are not indicated in the Contract Documents, shall be reported immediately to the Contracting Officer and utility owners involved. The Contracting

Officer and utility authorities shall be permitted free access to determine the measures deemed necessary to repair, relocate, or remove the utility.

C. For utility trenches, compact each layer of initial and final backfill soil material at 90 percent.

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3.4 EARTHWORK GENERAL REQUIREMENTS

A. Erosion Protection: Prevent erosion of the site and turbidity in adjacent waterbodies of the site at all times. Conform to all the requirements as per Section 01 57 13 – Temporary Storm Water

Pollution Prevention and Section 31 25 00 – Erosion and Sediment Controls.

B. Construction Traffic: Protect exposed soil layers with high moisture content from excessive wheel loads.

C. On-Site Excavation:

1. Do not excavate or remove any material from the project site which is not within the designated excavation.

2. The Contractor is responsible for retaining enough excavated material for reuse for any actions and for disposing excess material off-site.

D. Disposal of Surplus Material:

1. Excess earth materials, unsuitable materials, and debris shall be removed from the site and disposed of in a legal manner. The Contractor is to provide the CO with copies of the documentation for the legal disposal of materials.

E. Maintenance of Excavations, Slopes, and Embankments:

1. Reroute surface water runoff away from excavated areas. Do not allow water to accumulate in excavations. Do not use excavated trenches as temporary drainage ditches.

2. Maintain slopes and embankments until final completion and acceptance of the Work.

Promptly repair slides, slipouts, washouts, settlements, and subsidence that occur for any reason, and refinish the slope or embankment to the indicated lines and grades.

F. Safeguarding of Walls: Heavy equipment and rollers shall not be operated within four feet (4') of walls.

G. Dust and Dirt Control: Provide satisfactory control or remove dust and/or dirt at the project site and adjacent roadways whenever traffic or buildings that are occupied or in use, are affected.

H. Archeological Sensitive Area Protection: Follow Section 01 35 13 - Archeological and Historical

Resource Protection for work within an archeologically sensitive area. Avoid unnecessary actions, stockpiling, compaction, clearing of any subsurface work in this area.

I. Wetland:

1. Effects on hydrology and fluvial process: Action in wetlands shall only have negligible to minor, new adverse effects on site hydrology and fluvial processes, including flow, circulation, velocities, hydroperiods, water level fluctuations, sediment transport, channel morphology, and so on. Care shall be taken to avoid any rutting caused by vehicles or equipment.

2. Effects on fauna: Action in wetlands shall only have negligible to minor, new adverse effects on normal movement, migration, reproduction, or health of aquatic or terrestrial fauna, including at low flow conditions.

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3. Water quality protection and certification: Action in wetlands shall be conducted to avoid degrading water quality to the maximum extent practicable. Measures shall be employed to prevent or control spills of fuels, lubricants, or other contaminants from entering the waterway or wetland.

4. Erosion and siltation controls: Appropriate erosion and siltation controls shall be maintained during construction, and all exposed soil or fill material shall be permanently stabilized at the earliest practicable date.

5. Proper maintenance: Structure or fill shall be properly maintained to avoid adverse impacts on aquatic environments or public safety.

6. Heavy equipment use: Heavy equipment use in the wetlands shall be avoided if at all possible. If used in a wetland area, heavy equipment shall be placed on mats, or other measures taken to minimize soil and plant root disturbance and to preserve preconstruction conditions.

7. Stockpiling material: Excavated material shall not be placed in the wetland area. Runoff from stockpiled material adjacent to the wetland shall be controlled with silt fencing, filter cloth, wattles/fiber rolls, or other appropriate means to prevent reentry into the waterway or wet meadow.

8. Topsoil storage and reuse: Revegetation of disturbed soil areas shall be facilitated by salvaging and storing existing topsoil and reusing it in restoration efforts. Topsoil storage shall be as short a time as possible to prevent loss of seed and root viability, loss of organic matter, and degradation of the soil microbial community.

9. Native plants: Where plantings or seeding is required, native plant material shall be obtained and used. Techniques shall be implemented to foster rapid development of target native plant communities and to eliminate invasion by exotic or other undesirable species.

3.5 GROUND SURFACE PREPARATION

A. Complete clearing and grubbing operations in accordance with Section 31 10 00 Site Clearing.

Where new material is to be placed on compacted subgrade, scarify ground surface until surface is free from ruts, hummocks or other uneven features, which would prevent uniform compaction and bond between old and new material.

B. Prior to placing any new sections of asphalt or concrete pavement, the entire subgrade shall be scarified to a depth of six-inches (6”). In areas where existing pavement is to be removed and replaced the existing compacted subgrade may be reused if the subgrade meets specified compaction. In areas of existing subgrade that do not meet the specified compaction, materials shall be removed, replaced and compacted to meet the specified proctor density. Adjust moisture content and compact as hereinafter specified.

C. Graded/Compacted Soil Areas: Scarify ground surface until surface is free of ruts, hummocks, or uneven features that would prevent uniform compaction band between existing soil and fill material. In areas where fill required existing material may be reused. In areas that do not meet the specified compaction, material shall be removed, replaced, and compacted to meet specified proctor density.

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3.6 ROUGH GRADING AND FILLING

A. Prior to commencement of structural earthwork, perform such soil removal and filling as may be required to facilitate the progress of the Work and bring all elevations to the rough grading lines indicated on Contract Drawings. Grading shall be by blading or as herein specified.

B. Fill or backfill holes, swales, and low points that will not otherwise be removed in the course of the Work, to the indicated grades.

3.7 DEWATERING

A. Prevent surface water and ground water from entering excavations, from ponding on prepared subgrades, and from flooding Project site and surrounding area. Discharge locations shall be identified in a preconstruction submittal and approved by the CO. All discharge shall avoid turbidity or erosion into adjacent water bodies.

B. Protect subgrades from softening, undermining, washout, and damage by rain or water accumulation.

1. Reroute surface water runoff away from excavated areas. Do not allow water to accumulate in excavations. Do not use excavated trenches as temporary drainage ditches.

2. Install a dewatering system to keep subgrades dry and convey ground water away from excavations. Maintain until dewatering is no longer required.

3.8 EXPLOSIVES

A. Explosives: Do not use explosives.

3.9 EXCAVATION

A. The bottoms of excavations shall be level, firm, undisturbed earth, clean and free from loose material, debris, and foreign matter.

B. Excavate to the lines and grades indicated on the Contract Drawings.

C. Support and maintain excavation so that sides are stable and will not move. Excavations may be maintained by sloping cut faces where space permits, or by providing structural support of earth walls.

D. Limits of excavations shall allow for adequate working space for installing forms, and as required for safety of personnel.

E. Excavation and its restoration, when conducted for convenience of the Contractor, shall be at no additional expense to the Government.

F. Place excavated material at sufficient distance from edge of excavation so as not to cause cave-ins or bank slides, but in no case closer than three feet (3') from the edge of excavations.

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G. Condition excavated earth material that is suitable for backfill or embankment for re-use. Test, screen, and mix as necessary to meet specified requirements.

H. Footing excavations shall be free of any loose, soft, or disturbed material; and water prior to placement of reinforcing bars and concrete.

I. The on-site existing fill material and residuum may generally be excavated with moderate- to heavy-duty earthmoving or excavation equipment in good operating condition. Excavations are not anticipated to extend into weathered shale bedrock layers.

J. Operation of medium- to heavy-duty construction equipment near this fill residuum layer may result in subgrade instability, particularly during spring thaw and rainy weather. Construction during these periods may require stabilization of the subgrade soils. Excavations should not be left open during non-construction seasons such as winter months.

K. Equipment and procedures that do not cause significant disturbance to the excavation bottoms should be used. Excavators and backhoes with buckets having large claws to loosen the soil should be avoided when excavating the bottom approximately 6 to 12 inches of excavations as such equipment may disturb the excavation bases.

L. The contractor should provide safely sloped excavations or an adequately constructed and braced shoring system, in compliance with Occupational Safety and Health Administration (OSHA) guidelines (OSHA, 2005), for employees working in an excavation that may expose employees to the danger of moving ground. If material is stored or equipment is operated near an excavation, stronger shoring should be used to resist the extra pressure due to superimposed loads.

3.10 TEMPORARY EXCAVATIONS

A. Temporary slopes in the near-surface fill and residual soils should generally be considered a Type

C soil when applying Occupational Safety and Health Administration (OSHA) regulations. For these soil conditions, OSHA recommends a temporary slope inclination of 1.5 to 1 (horizontal to vertical) or flatter for excavations 20 feet or less in depth. Steeper cut slopes may be utilized for excavations less than 4 feet deep depending on the strength, moisture content, and homogeneity of the soils as observed in the field. Additional care and considerations of excavation slopes should be made during wet weather conditions. Appropriate slope inclinations should be evaluated in the field by an OSHA-qualified “Competent Person” based on the conditions encountered.

B. The contractor should provide safely sloped excavations or an adequately constructed and braced shoring system, in compliance with OSHA regulations, for employees working in excavations that may expose them to the danger of moving ground. Reducing the inclination of the sidewalls of the excavations, where feasible, may increase the stability of the excavations. If construction or earth material is stored, or equipment is operated near an excavation, flatter slope geometry or shoring should be used during construction.

C. The existing retaining wall footings will be at risk of undermining, if the limits of the temporary site excavations encroach to the existing retaining wall footings by a distance that is defined as two times the width of the existing footing (measured from the bottom edge of the existing footing).

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3.11 EMBANKMENT CONSTRUCTION

A. Lift thickness for fill will be dependent upon the type of compaction equipment utilized, but should generally be placed in lifts not exceeding 8 inches in loose thickness.

B. Fill materials should not be placed, worked, rolled while they are frozen, thawing, or during poor/inclement weather conditions.

C. Compaction areas should be kept separate, and no lift should be covered by another until relative compaction and moisture content within the recommended ranges are obtained.

D. Use of a CLSM should be considered in lieu of compacted fill for areas with low tolerances for surface settlements and vibrations, and in areas with difficult access for compaction equipment.

E. Finished fill slopes shall be constructed at an inclination no steeper than 2:1. Fill slopes shall be overbuilt and trimmed back as necessary to expose a well-compacted surface.

F. Structural fill supporting footings shall extend laterally outside of the footing base at a 1H:1V or flatter inclination projected down and away from the bottom edges of the footing.

G. Routine maintenance of slope sloughing and erosion should be anticipated. Fill slopes and areas disturbed during construction shall be planted with vegetation to reduce erosion.

H. Remove material that cannot be compacted to the required density within specified tolerances, and replace with suitable material at no additional expense to the Government.

3.12 CONTROLLED LOW STRENGTH MATERIAL

A. Use of CLSM should be considered in lieu of compacted fill for areas with low tolerances for surface settlements, for excavations that extend below the groundwater table and in areas with difficult access for compaction equipment.

B. CLSM should be placed in lifts of 5 feet or less with a 24-hour or more curing period between each lift.

3.13 STRUCTURAL FILL SUBGRADE PREPARTION

A. Foundations shall be founded on compact to very dense sand and gravel, or properly compacted structural fill.

B. Subgrade for roads and pavements shall be compact to very dense sand and gravel (with varying amounts of silt and clay), stiff/compact silty clay, or properly compacted structural fill.

C. Notify CO when excavations have reached required subgrade and before placing any fill material.

If CO determines that unsatisfactory soil is present, continue excavation and replace with compacted backfill or fill material as directed.

D. If the soil exposed during construction is loose or otherwise un-suitable it should be conditioned, if practical, or removed and replaced with compacted structural fill.

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E. For pavement, slab, structural fill, or foundation subgrade, any suitable material loosened during excavation or other activities prior to placement of structural fill, pavement or slab materials, or foundations shall be compacted.

F. If wet fine-grained soils are encountered at the subgrade, geotextile per Section 2.1.J. shall be installed prior to backfilling.

G. Where fill will be placed adjacent to an existing slope, steps shall be excavated into the existing slope to help “key” the new fill into the slope.

H. Native component subgrade that becomes loosened or otherwise degraded shall be recompacted, over-excavated and replaced with a suitable structural fill, or admixed with a moisture reducing agent or cement treated base (CTB).

I. Structural fill shall be placed on firm, un-yielding subgrade prepared in accordance with these specifications.

J. Perform all cutting, blading, and shaping as required to cut and shape the subgrade to the grades and elevations indicated.

K. Subgrade preparation includes fine grading, reworking as necessary, and preparation of cut, fill, or embankment upon which structure and equipment foundations, pipe, base, and pavement will be placed.

L. The upper 6 inches of subgrade under pavements shall be moisture conditioned and compacted to at least 95 percent relative compaction and should be smooth and unyielding.

M. After the material has been thoroughly mixed and moisture-conditioned, accurately construct and fine grade the subgrade to indicated line, grade, and contour with high and low spots eliminated.

Compact for full width to the specified density. Remove soft spots developed during working, fill with approved material, and re-compact.

N. If soil moisture conditions allow, after exposing the subgrade for pavement, slab, or structural fill, proof-rolling the subgrade with a loaded dump truck or other heavy wheeled vehicle to identify soft pockets and areas of excess yielding. Do not proof-roll wet or saturated subgrades.

1. Completely proof-roll subgrade in one direction, repeating proof-rolling in direction perpendicular to first direction. Limit vehicle speed to 3 mph (5km/h).

2. Proof-roll with loaded 10-wheel, tandem-axle dump truck weighing not less than 15 tons

(13.6 tonnes).

3. Excavate soft spots, unsatisfactory soils, and areas of excessive pumping or rutting, as determined by CO and replace with compacted backfill or fill as directed.

O. Authorized additional excavation and replacement material will be paid for according to Contract provisions for unit prices.

P. Reconstruct subgrades damaged by freezing temperatures, frost, rain, accumulated water, or construction activities, as directed by CO, without additional compensation.

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3.14 STORAGE OF SOIL MATERIALS

A. Stockpile borrow soil materials and excavated satisfactory soil materials without intermixing.

Place, grade, and shape stockpiles to drain surface water. Cover to prevent windblown dust and reduce potential for invasive species establishment.

1. Stockpile soil materials away from edge of excavations. Do not store within drip line of remaining trees.

2. Temporary stockpiles shall be no higher than 5 feet.

3.15 BACKFILL

A. Place backfill on subgrades free of mud, frost, snow, or ice.

B. Place backfill in horizontal layers not to exceed eight inches (8") of loose material, and compact each layer to specified density before the next layer is placed.

C. Place backfill material in such a manner that unbalanced horizontal loads will not be applied to a newly placed structure or portion of a structure, utilities, or pipelines.

D. Do not backfill on or against structural concrete until the specified 28-day concrete strength has been attained.

E. Do not use compaction equipment and methods that produce excessive horizontal or vertical earth pressures.

3.16 UTILITY TRENCH BACKFILL

A. Place backfill on subgrades free of mud, frost, snow, or ice.

B. Trenches shall be graded uniformly sloped between pipe elevations as shown on the drawings.

C. Place and compact bedding course on trench bottoms and where indicated. Shape bedding course to provide continuous support for bells, joints, and barrels of pipes and for joints, fittings, and bodies of conduits.

D. Place and compact initial backfill of pipe bedding material to a height of 12 inches (300 mm) over the utility pipe or conduit.

1. Carefully compact initial backfill under pipe haunches and compact evenly up on both sides and along the full length of utility piping or conduit to avoid damage or displacement of piping or conduit. Coordinate backfilling with utilities testing.

E. Controlled low-strength material: Where indicated, place initial backfill of controlled low-strength material to a height of 12 inches (300 mm) over the utility pipe or conduit.

F. Backfill voids with satisfactory soil while installing and removing shoring and bracing.

G. Backfill and compact over excavations to ninety five (95) percent relative compaction with bedding material. There shall be no additional payment to the Contractor for over excavations not

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directed by the CO. Remove unsatisfactory material encountered below the grades shown as directed by the CO and replace with bedding material. Payment for removal and replacements of such unsatisfactory material directed by the CO shall be made in accordance with the provisions of the General Conditions.

H. Install warning tape directly above utilities, 12 inches (300 mm) below finished grade, except 6 inches (150 mm) below subgrade under pavements and slabs.

3.17 SOIL MOISTURE CONTROL

A. Granular soils (on-site soils that classify as sands/gravels, or import soils) used as engineered fill should be moisture-conditioned to moisture contents within 2 percent of optimum moisture content.

1. Do not place backfill or fill soil material on surfaces that are muddy, frozen, or contain frost or ice.

2. Remove and replace, or scarify and air dry otherwise satisfactory soil material that exceeds optimum moisture content by 2 percent and is too wet to compact to specified dry unit weight.

3.18 COMPACTION OF SOIL BACKFILLS AND FILLS

A. Place backfill and fill soil materials in layers not more than 8 inches (200 mm) in loose depth for material compacted by heavy compaction equipment, and not more than 4 inches (100 mm) in loose depth for material compacted by hand-operated tampers.

B. Place backfill and fill soil materials evenly on all sides of structures to required elevations, and uniformly along the full length of each structure.

C. Fill compaction shall be verified by means of in-place density tests performed per ASTM D6938

(or appropriate alternative when ASTM D6938 is not suitable for the fill material) during fill placement so that compaction may be evaluated as earthwork progresses.

D. Compact soil materials to not less than the following percentages of maximum dry unit weight according to ASTM D 1557:

Fill Application Minimum

Compaction

Building Pad 95

Footing subgrade or bearing pad 95

Slab-on-grade floor subgrade and subbase 95

Retaining wall footing subgrade 95

Concrete slab subgrades 95

Asphalt pavement base and subbase 95

Asphalt pavement subgrade, within 3 feet of finished grade 95

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Asphalt pavement subgrade, more than 3 feet below finished grade 92

Retaining wall backfill 92

Footing and stem wall backfill 92

Graded Compacted Soil Areas 95

Landscape Slope Areas 80

3.19 GRADING

A. General: Uniformly grade areas to a smooth surface, free of irregular surface changes. Comply with compaction requirements and grade to cross sections, lines, and elevations indicated.

1. Provide a smooth transition between adjacent existing grades and new grades.

2. Cut out soft spots, fill low spots, and trim high spots to comply with required surface tolerances.

B. Site Grading: Slope grades to direct water away from buildings and to prevent ponding. Finish subgrades to required elevations within the following tolerances:

1. Pavements: Plus or minus 1/2 inch (13 mm).

C. Compaction of Landscape Slope Areas:

1. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment.

Compaction operations shall be continued until slopes are stable, compact to a density as specified in Paragraph 3.18.D. Permanent fill slopes shall not exceed four-to-one (4:1)

(horizontal to vertical).

2. Where natural slopes are steeper than twenty percent (20%) in grade and the placement of fill is required, cut benches shall be provided at the rate of one bench for each five feet

(5’) in height (minimum of two benches). Benches shall be at least ten feet (10’) in width. Fill shall be placed on completed benches as outlined within this specification.

D. Compaction of Fill for Hardscape Areas:

1. Select fill material shall be placed and mixed in evenly spread layers. After each fill layer has been placed, it shall be uniformly compacted. Fill materials shall be placed such that the thickness of loose material does not exceed eight-inches (8”) and the compacted lift thickness does not exceed six-inches (6”).

2. Compaction shall be obtained by the use of sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other equipment required to meet specifications. Granular fill shall be compacted using vibratory equipment or other equipment required to meet specifications.

Compaction of each layer shall be continuous over the entire area. Compaction equipment shall make sufficient passes to ensure that the required density is obtained.

Refer to Paragraph 3.18.D. herein for criteria.

3.20 REMEDIAL GRADING

A. Remedial grading work (removal and replacement of the fill material) be performed to treat the potentially compressible undocumented fill prior to the placement of new spread footing foundations. The remedial grading recommendations are for new spread footing foundations

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only. Alternatively, the existing fill section may be improved through the use to grout injection or dynamic compaction techniques.

B. The remedial grading work should generally consist of:

1. Removing the loose or soft, potentially compressible soils to expose a competent natural subgrade.

2. Scarifying, moisture conditioning, and compacting the disturbed subgrade soils to a depth of about 12 inches.

3. Placing, moisture conditioning, and compacting the new fill materials.

Depending on the proposed finished grade elevations, the thickness of the removal and re-compaction will vary.

C. The proposed building improvements may be supported on conventional spread-footing foundations bearing on a layer of engineered fill extending to firm residual soils. The thickness of the new engineered fill layer will depend on the design depth of the new footing and the depth of the undocumented fill below the new footing. This new engineered fill layer should extend laterally beyond the footing limits 1-foot for each foot of over-excavation depth. The removal and replacement needed to construct new spread footing foundations may not be feasible and utilization of an alternate deep foundation systems may be needed.

D. The slab-on-grade system should be supported on a minimum of 3 feet of engineered fill or, alternatively, a structural floor system may be considered.

E. New pavements and exterior flatwork should be placed on 12 inches or more of compacted engineered fill.

3.21 SUBBASE AND BASE COURSES

A. Place subbase and base course on subgrades free of mud, frost, snow, or ice.

B. On prepared subgrade, place subbase and base course under pavements and walks as follows:

1. Place base course material over subbase course under hot-mix asphalt pavement.

2. Shape subbase and base course to required crown elevations and cross-slope grades.

3. Place subbase and base course 6 inches (150 mm) or less in compacted thickness in a single layer.

4. Place subbase and base course that exceeds 6 inches (150 mm) in compacted thickness in layers of equal thickness, with no compacted layer more than 6 inches (150 mm) thick or less than 3 inches (75 mm) thick.

5. Compact subbase and base course at optimum moisture content to required grades, lines, cross sections, and thickness to not less than 95 percent of maximum dry unit weight according to ASTM D 1557.

3.22 FIELD QUALITY CONTROL

A. Testing Agency: Contractor shall engage a qualified independent geotechnical engineering testing agency to perform field quality-control testing.

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B. Allow testing agency to inspect and test subgrades and each fill or backfill layer. Proceed with subsequent earthwork only after test results for previously completed work comply with requirements.

C. Footing Subgrade: At footing subgrades, at least one test of each soil stratum will be performed to verify design bearing capacities. Subsequent verification and approval of other footing subgrades may be based on a visual comparison of subgrade with tested subgrade when approved by the CO.

D. Testing agency will test compaction of soils in place according to ASTM D 1556, ASTM D 2167, ASTM D 2922, and ASTM D 2937, as applicable. Tests will be performed at the following locations and frequencies:

1. Paved Areas: At subgrade and at each compacted fill and backfill layer, at least 1 test for every 2000 sq. ft. (186 sq. m) or less of paved area or building slab, but in no case fewer than 3 tests.

2. Trench Backfill: At each compacted initial and final backfill layer, at least 1 test for each

150 feet (46 m) or less of trench length,…