312333 trenching and backfilling.doc

SECTION 31 23 33

TRENCHING and Backfilling

PART 1 – GENERAL

1.01 Related Documents

A.

Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section, including – but not limited to – the following.

1.

Section 01 35 43 – Environmental Procedures: Requirements for erosion and sediment control measures.

Section 01 57 13 – Temporary Erosion and Sediment Control: Requirements for erosion and sedimentation control measures.

1.02 Summary

The Work of this Section includes:

Excavating trenches for drainage systems and utilities [from building service connection to municipal utilities].

2.

Compacted bed and compacted fill over utilities [to subgrade elevations].

3.

Compaction requirements.

B.

Related Requirements:

Section 31 23 00 – Excavation and Fill: Building excavation and backfilling.

Section 32 91 19 – Landscape Grading.

Section 33 05 13 – Manholes and Structures: Storm and sanitary manholes, catch basins and inlets.

4.

Section 33 11 01 – Water Utility Distribution Piping (Ductile and Cast Iron).

Section 33 11 02 – Water Utility Distribution Piping (PVC).

Section 33 11 03 – Water Utility Distribution Piping (Copper).

5.

Section 33 30 00 – Sanitary Sewerage Utilities.

6.

Section 33 40 00 – Storm Drainage Utilities.

7.

Section 33 46 00 – Subdrainage: Building perimeter tile drainage [and connections to municipal sewer].

1.03

REFERENCES

ASTM International:

Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates (ASTM C‑136‑96a).

Standard Classification for Sizes of Aggregate for Road and Bridge Construction (ASTM D‑448‑03a).

Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft‑1bf/ft3 (600 kN‑m/m3)) (ASTM D‑698‑00a).

Standard Test Method for Density and Unit Weight of Soil in Place by the Sand‑Cone Method (ASTM D‑1556‑00).

Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 lb‑lbf/ft3 (2,700 kN‑m/m3)) (ASTM D‑1557‑00).

Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) (ASTM D‑2487‑00).

Standard Test Methods for Density of Soil and Soil‑Aggregate in Place by Nuclear Methods (Shallow Depth) (ASTM D‑2922‑96e1).

8.

Standard Test Method for Water Content of Soil and Rock in Place by Nuclear Methods (Shallow Depth) (ASTM D‑3017‑96e1).

9.

Standard Test Methods for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density (ASTM D‑4254‑00).

B.

State of [Ohio] [___________] Department of [Transportation (ODOT)] [____________]: [Latest edition of Construction and Material Specifications (ODOT CMS)] [Specifications and standards].

B.

Commonwealth of Pennsylvania Department of Transportation (PENNDOT): Construction Specifications (Publication 408/2003).

C.

[City of [____________]] [Local] Department of [Transportation] [____________]: Specifications and standards.

D.

United States Air Force (USAF or AF) Form: Base Civil Engineering Work Clearance Request (AF 103).

1.04

SUBMITTALS

A. General: Prepare, review, approve, and submit the following per the General Requirements.

B. Informational Submittals (Test Reports): Submit the following in accordance with the General Requirements:

Sieve analysis of select fill materials.

Field density test reports.

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

C.

Contract Closeout Submittals (Project Record Documents): Accurately record horizontal dimensions, elevations or inverts, and slope gradients of the following:

Utilities to remain in place.

Rerouted utilities.

New utilities.

PART 2 – PRODUCTS

2.01

MATERIALS

A.

Common Fill (Subsoil): Excavated material, graded free of lumps larger than 6 inches, rocks larger than 3 inches.

Select [Premium] Bed and Fill:

Type A – [Coarse Stone] [Gravel: [Pit run] [Angular] [Crushed], [Washed] natural stone; free of shale, clay, friable materials and debris; graded per [ASTM C‑136] [ODOT CMS Item 304] [and PENNDOT Section 703 – Aggregate.] [within the following limits (slag will not be allowed):]

Sieve Size Total Percent Passing

2 inches

1 inch

3/4 inch

5/8 inch 75 to 100

3/8 inch 55 to 85

No. 4 35 to 60

No. 16 15 to 35

No. 40 10 to 25

2 Inches

1 Inch 70 to 100

3/4 Inch 50 to 90

No. 4 30 to 60

No. 40 7 to 30

No. 200 0 to 13

Type A – Coarse Interlocking Aggregate Stone: Angular, natural stone; free of shale, clay, friable materials, and debris, Size Nos. 6, 67, 7, 78, or 8 per ASTM D‑448 and graded per ASTM C‑136.

Type B – Pea Gravel: Natural stone; [washed], free of clay, shale, and organic matter; 1/4 inch minimum to 5/8 inch maximum size graded per ASTM C‑136 [and PENNDOT Section 703 – Aggregate].

Type C – Sand: Natural river or bank sand; [washed], free of silt, clay, loam, friable or soluble materials, and organic matter; graded per ASTM C‑136 [and PENNDOT Section 703 – Aggregate.] [within the following limits:]

No. 4

No. 14 10 to 100

No. 50 5 to 90

No. 100 4 to 30

No. 200

C.

Plastic Marking Tape:

Acid and alkali‑resistant polyethylene film, 6‑inches wide with minimum thickness of 0.004 inch; with minimum strength of 1750 PSI lengthwise and 1500 PSI crosswise.

Furnish and install tape specifically manufactured for marking and locating underground utilities, including:

a.

Integral wires, foil backing or other means to enable detection by a metal detector when the tape is buried up to 3‑feet deep.

b.

Metallic core protected with protective jacket or other means to protect it from corrosion.

c.

Color and continuous printed inscription identifying specific utility:

1) Red: Electricity.

2) Orange: Telephone, Telegraph, Television, or Police and Fire Communications.

3) Yellow: Gas, Oil or other dangerous materials.

4) Green: Sewer Systems.

5) Blue: Water Systems.

2.04 Source quality control

A.

Perform test and analysis of fill materials per ASTM [D‑698] [or] [D‑1557] for cohesive materials and ASTM D‑4254 for cohesionless soils and in accordance with the General Requirements.

PART 3 – EXECUTION

3.01 ExaminaTION

Verify that:

Stockpiled fill to be reused is approved.

Installation of drainage at perimeter of foundation has been inspected.

Surfaces of areas to be backfilled are free of debris, snow, ice, or water and are not frozen.

3.02

PREPARATION

Notify the [Ohio Utility Protection Service (OUPS)] [____________] by telephone [((800) 362 ‑ 2764)] [____________] at least [48] [72] hours prior to excavating, fencing, planting, or other work that disturbs earth in order for them to locate and identify the existing underground utilities.

Notify owners of underground utilities who are not current members of OUPS [_____] at least [two] [three] working days in advance.

A.

The Work shall not commence until the Contractor is in possession of a signed AF 103.

An approved digging permit must be obtained by the contractor prior to digging.

The Government will provide a general map of the location of utilities. Drawings are not complete and accuracy cannot be guaranteed. The Contractor shall locate and verify existing utilities.

Protection:

Protect trees, shrubs, lawns and other features remaining as portion of final landscaping.

Protect benchmarks, [existing structures,] [fences,] roads, sidewalks, paving, and curbs from equipment and vehicular traffic.

Maintain and protect utilities that pass through work area and are indicated to remain:

a.

Identify and flag aerial and surface utilities.

b.

Identify known underground utilities. Stake and flag locations.

c.

Where unmarked utilities are uncovered within the work area, notify the [Architect/Engineer] [,] [Contracting Officer] [Owner] and the authorities having jurisdiction (AHJ), and take precautions to prevent interruption of service. Should such lines or services be damaged, broken, or interrupted through negligence, repair and restore immediately without additional cost to utility owner.

Repair damage caused by the Work of this Section.

C.

Identify required lines, levels, contours, and datum.

D.

Notify [utility company] [___________] to remove [and relocate] existing utilities.

E.

If conditions are encountered that are different than those shown on the Drawings, notify the [Architect/Engineer] [Contracting Officer] [Owner] and discontinue affected work in area until notified to resume work.

3.03 Construction

Excavation:

Excavate subsoil required for [storm sewer,] [sanitary sewer,] [water,] [and] [gas] [and] [______________] piping from building service connections to municipal utilities [and onsite mains].

Cut trenches sufficiently wide to enable installation of utilities and allow inspection.

Hand‑trim excavation and leave free of loose matter. [Hand‑trim for bell and spigot pipe joints.]

Remove lumped subsoil, boulders, and rock up to [one‑third of a] [_____] cubic yard, measured by volume.

Do not interfere with normal [45] [_____] degree bearing splay of foundation excavations.

Correct unauthorized excavation at no additional cost to the [Government] [Owner].

Fill over‑excavated areas under pipe bearing surfaces as directed by the [Architect/Engineer] [Contracting Officer].

[Stockpile excavated material in area designated on the Site or where directed [and remove excess subsoil not being reused, from the Site]].

[Remove excavated material from the Site].

Do not leave trenches or work areas open or uncovered during non‑working hours.

Backfilling:

When necessary, compact subgrade surfaces to density requirements for backfill material.

Bed pipes with Type [A,] [B,] [or] [C] select fill material in continuous layers not exceeding 6 inches loose depth compacted to a minimum of 98 percent. Total depth of bedding shall be as indicated on the Drawings.

Support pipe [and conduit] during placement and compaction of bedding fill.

Backfill trenches to contours and elevations. Backfill systematically, as early as possible, to allow maximum time for natural settlement. Do not backfill over porous, wet, or spongy subgrade surfaces.

Place and compact Type [A] [C] [___] select fill material in continuous layers not exceeding [6] [8] [12] [_____] inches loose depth compacted to a minimum of [98] [95] [____] percent.

Place and compact common fill material in continuous layers not exceeding [8] [12] [_____] inches loose depth compacted to a minimum of [98] [95] [____] percent.

Employ a placement method so as not to disturb or damage [foundation perimeter drainage] [foundation dampproofing] [foundation waterproofing and protective cover] [and] [utilities in trenches] [______________].

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

Remove surplus backfill materials [from the Site] [_____].

10.

Leave stockpile areas completely free of excess fill materials.

C.

Tolerances (Top Surface of Backfilling): Plus‑or‑minus [1/4] [1] [_____] inch[es].

D.

Plastic Marking Tape: Install warning tapes directly above pipe at a depth of [18] [____] inches below finish grade.

Exception: Where otherwise indicated.

E.

Compaction:

For soils that exhibit a well‑defined moisture density relationship (cohesive soils) determined per ASTM [D‑698] [D‑1557], compact soil to not less than the scheduled percentages of maximum density.

For soils that will not exhibit a well‑defined moisture density relationship (cohesionless soils), compact soil to not less than the scheduled percentages of relative density, determined per ASTM D‑4254.

F.

Dewatering:

Prevent surface water and subsurface or ground water from flowing into excavations and from flooding the Site and surrounding areas.

Do not allow water to accumulate in excavations. Remove water to prevent soil changes detrimental to stability of subgrades. Provide and maintain pumps, well points, slumps, suction and discharge lines, and other dewatering system components necessary to convey water away from excavations.

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

3.04 Field QUALITY CONTROL

A.

The [Government] [Owner] [will] [might] employ and pay for soil testing and inspection service for quality control testing during earthwork operations in accordance with the General Requirements. Allow testing service to inspect and approve subgrades and fill layers before further construction work is performed.

A.

Make at least one field density test of subgrade for every 50 lineal feet, but in no case less than three tests.

B.

Take at least two field density tests of backfill at locations and elevations as directed by the [Architect/Engineer] [Contracting Officer].

C.

If tests indicate that the Work of this Section does not meet specified requirements, remove the Work, replace, and re‑test at no additional cost to the [Government] [Owner].

3.05

PROTECTION

A.

Protect excavation by shoring, bracing, sheet piling, underpinning, or other methods required to prevent cave‑in or loose soil from falling into excavation.

B.

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

C.

Protect the following from frost:

Bottom of excavations.

Soil adjacent to and beneath foundations.

D.

Grade excavation top perimeter to prevent surface water runoff into excavation.

END OF SECTIOn 31 23 33

31 23 33-10

TRENCHING AND BACKFILLING

12910-330

Revised 3/2/09

12910-330

TRENCHING AND BACKFILLING

31 23 33-9

Revised 3/2/09