31_23_33_-_UTILITIES_TRENCHING_AND_BACKFILLING.pdf

Okaloosa County June 2026 “ITB TDD 65-26” Issue for Bid

TRENCHING AND BACKFILLING

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SECTION 31 23 33

TRENCHING AND BACKFILLING

PART 1 - GENERAL

1.1 SUMMARY

A. Section Includes:

1. Requirements for excavating, filling, and other earth Work for linear, buried utility projects, including:

a. Field conditions.

b. Soil and aggregate materials.

c. Test pits.

d. Excavation.

e. Preparation of subgrades.

f. Filling and compacting.

g. Rough grading.

h. Disposal of excavated spoil materials.

B. Related Requirements Include, but are not necessarily limited to, the following:

1. Section 31 10 00 - Site Clearing.

2. Section 31 22 19 - Finish Grading.

1.2 PRICE AND PAYMENT PROCEDURES

A. Measurement:

1. Contractor shall provide all labor, materials, construction equipment and machinery, tools, and incidentals required or necessary for performing all trenching, backfilling, and related earth Work for the Contract, including all Work related to excavating, preparing subgrades, providing and stockpiling materials, filling with required materials, compacting, grading, proper disposal of excess spoil materials, and all other Work required by this Section. This Section includes trenching, backfilling, and related earth Work required for constructing:

buried utilities, including piping and, where applicable, other Underground Facilities; site improvements (including pavement, sidewalks, curbs, and the like); subgrade preparation for other Work; and all other trenching, backfilling, and related earth Work required by the Contract Documents and not addressed under other Specifications sections.

2. Unless expressly indicated otherwise in the Contract Documents, such as Section 01 22 00 - Measurement and Payment, the Work of this Section is included in the various lump sum and unit price bid/pay items for the Contract.

3. All Work under this Section is unclassified and covered by this Section and the associated bid/payment item(s). No separate payment will be made for removing, handling, or disposing of rock (unless the Contract includes a separate bid/pay item specifically for rock excavation or rock removal), stones, concrete (whether or not reinforced), debris, stumps, and other material, regardless of moisture content, unless such material constitutes an unforeseen Hazardous Environmental Condition and Work associated with such Hazardous Environmental Condition is not included in the Contract.

4. Where excavation of test pits is required by the Contract Documents or Engineer, payment for such test pits will be in accordance with Paragraph 3.2.B of this Section and other applicable provisions of the Contract Documents.

1.3 REFERENCES

A. Terminology:

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1. The following terms are not defined and are not indicated with initial capital letters but, when used in this Section, have the following meaning:

a. “Borrow” means material required for trenching, backfilling, and related earth Work in excess of quantity of suitable material available from required grading, cuts, and excavations at the Site. Borrow may be necessary even though not otherwise expressly required by the Contract Documents.

b. “Cohesive soil” means clay (fine grained soil), or soil with a high clay content, which has cohesive strength. Cohesive soil does not crumble, can be excavated with vertical or near-vertical sideslopes, and is plastic when moist. Cohesive soil is difficult to break up when dry, and exhibits significant cohesion when submerged. Cohesive soils include clayey silt, sandy clay, silty clay, clay and organic clay.

c. “Cohesionless soil” means fill material that does not clump together; its grains remain separate and apart from each other. Cohesionless soils typically have a low proportion of fine (no. 200 mesh size and less) particles and may be soil material or granular material. The terms “cohesionless soils”, “cohesionless materials”, “non-cohesive soils”, and the like have the same meaning.

d. “Fill” means soil material, granular material, or other material indicated in this Section required for backfilling excavations or as material for achieving required rough grading.

Unless indicated otherwise in the context of a specific provision, the terms “fill” and “backfill” have the same meaning, as do derivative terms such as, “filling” and “backfilling”. When used by itself, the term “backfill” means material required for refilling an excavation.

e. “Foundations” means bottoms of manholes, chambers, vaults, and similar structures;

base slabs (slabs-on-grade); bearing directly on soil, granular material, or rock.

f. “Granular material” means gravel, sand, or silt, (coarse grained soil) with little or no clay content. Granular soil has no cohesive strength. Some moist granular soils exhibit apparent cohesion. Granular soil cannot be molded when moist and crumbles easily when dry. The terms “granular material”, “aggregate material”, and “granular soil” have the same meaning. Detailed requirements for specific types of granular material are indicated in Article 2.1 of this Section.

g. “Rock” means: igneous, metamorphic, or sedimentary rock or stone; boulders over two cubic yards in volume in open areas and boulders over one cubic yard in volume in trenches; and mass concrete; that cannot be removed using rippers and therefore requires drilling and blasting or use of large excavator-mounted pneumatic breakers. If rock is encountered during the Work, promptly furnish notice of differing subsurface condition in accordance with the General Conditions (as may be modified by the Supplementary Conditions); when necessary, Engineer will furnish requirements for rock removal via appropriate Contract modification. The following do not qualify as rock:

1) Soft, weathered or disintegrated rock that can be removed by normal excavating equipment, including bulldozers with rippers and large trackhoes with rock teeth or rock buckets.

2) Loose or previously blasted rock.

3) Broken stone in rock fills.

4) Rock or stone that falls into the excavation from outside limits of excavation shown or indicated in the Contract Documents.

5) Boulders that can be removed without drilling, blasting, or pneumatic breakers.

6) Pavements, sidewalks, and gutters of concrete, asphalt, or masonry.

h. “Subgrade” means the uppermost surface of native soil material unmoved from cuts;

the bottom of excavation.

i. “Trenching” means excavating for buried utilities, other Underground Facilities, and related excavation Work. In this Section, the words, “trenching” and “excavating” have the same meaning. In this Section, the word “excavation”, whether singular or plural, is general and includes trenching.

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j. “Unauthorized excavation” means removing materials beyond limits shown or indicated in the Contract Documents or otherwise directed by Engineer.

k. “Unclassified”, when used in referring to trenching, excavating, or excavations, means excavation and disposal of all materials, of any description whatsoever, encountered in performing the Work, unless otherwise shown or indicated in the Contract Documents.

l. “Unsuitable soil materials” means soil or other materials encountered at or below subgrade elevation of insufficient strength, stiffness, or characteristics to support the Work in accordance with the Contract Documents or as determined by Engineer. The terms “unsuitable soil material”, “unsuitable soil”, and “unsuitable material” have the same meaning.

B. Reference Standards: Standards referenced in this section include, but are not necessarily limited to, the following:

1. American Association of State Highway and Transportation Officials (AASHTO):

a. AMRL R18 - AASHTO Accreditation Procedure Manual.

2. ASTM International (ASTM):

a. C33/C33M - Standard Specification for Concrete Aggregates.

b. D698 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using

Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)).

c. D1556 - Standard Test Method for Density and Unit Weight of Soil in Place by Sand-

Cone Method.

d. D1557 - Standard Test Methods for Laboratory Compaction Characteristics of Soil

Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)).

e. D2166 - Standard Test Method for Unconfined Compressive Strength of Cohesive Soil.

f. D2216 - Standard Test Methods for Laboratory Determination of Water (Moisture)

Content of Soil and Rock by Mass.

g. D2434 - Standard Test Methods for Measurement of Hydraulic Conductivity of Coarse-

Grained Soils.

h. D2487 - Standard Practice for Classification of Soils for Engineering Purposes (Unified

Soil Classification System).

i. D2850 - Standard Test Method for Unconsolidated-Undrained Triaxial Compression

Test on Cohesive Soils.

j. D3740 - Minimum Requirements for Agencies Engaged in Testing and/or Inspection of

Soil and Rock as Used in Engineering Design and Construction.

k. D4253 - Standard Test Methods for Maximum Index Density and Unit Weight of Soils

Using a Vibratory Table.

l. D4254 - Standard Test Methods for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density.

m. D4318 - Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of

Soils.

n. D6913 - Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using

Sieve Analysis.

o. D6938 - Standard Test Methods for In-Place Density and Water Content of Soil and

Soil-Aggregate by Nuclear Methods (Shallow Depth).

p. D7928 - Standard Test Method for Particle-Size Distribution (Gradation) of Fine-

Grained Soils Using the Sedimentation (Hydrometer) Analysis.

q. E329 - Standard Specification for Agencies Engaged in Construction Inspection, Testing, or Special Inspection.

1.4 QUALITY ASSURANCE

A. Regulatory Requirements:

1. Comply with Section 01 14 33 - Work in Rights-of-Way.

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B. Qualifications:

1. Contractor’s Testing Laboratory:

a. Retain the services of independent testing laboratory to perform testing and determine compliance with the Contract Documents of materials specified in this Section.

b. When Contractor is expressly required, by this Section’s “Field Quality Control” Article or elsewhere in the Contract Documents, to retain testing laboratory for tests required under this Section’s “Field Quality Control” Article, retain one testing laboratory for quality assurance testing and field quality control testing.

c. Testing laboratory shall possess current, valid accreditation from the AASHTO Materials Reference Laboratory (AMRL), in accordance with AASHTO AMRL R18, for ASTM D3740, for tests required for quality assurance testing indicated in this Article and field quality control testing indicated to be Contractor’s responsibility.

d. Testing laboratory shall comply with ASTM E329.

e. Testing laboratory shall be experienced in the types of testing required.

f. Selection of testing laboratory is subject to Engineer’s acceptance. Upon Engineer’s request, submit qualifications statement for testing laboratory, including name of entity, location, copies of applicable certifications, summary of entity’s experience, and names and qualifications of personnel who will perform the subject sampling and testing.

C. Quality Assurance Testing:

1. Quality assurance testing, which may also be regarded as source quality control testing, is in addition to field quality control testing required by this Section’s “Field Quality Control” Article.

2. Materials used in the Work may require testing and retesting, as directed by Engineer, during the Project. Allow free access to onsite material stockpiles, borrow sources, and other sources of aggregate and soil materials at all times. Tests not specifically indicated to be performed at Owner's expense (if any), including retesting of defective materials and defective Work, shall be at Contractor’s cost.

3. Contractor’s Testing Laboratory Scope for Quality Assurance Sampling and Testing:

a. Obtain samples and perform testing of proposed fill materials in the laboratory, at the

Site, and at borrow locations (if any) to provide assurance that the Work will comply with the Contract Documents.

b. Testing laboratory shall perform testing required to obtain data for selecting moisture content for placing and compacting fill materials.

c. Submit to Engineer, via Contractor, written results of each test.

4. Required Quality Assurance Material Testing by Contractor’s Testing Laboratory:

a. Perform the following quality assurance tests on materials to be incorporated into the Work. Submit results of such tests to Engineer and obtain Engineer’s acceptance thereof prior to incorporating the subject materials into the Work.

b. Gradation in accordance with ASTM D6913 and ASTM D7928. Perform one test for every 1,000 cubic yards of each material to be incorporated into the Work.

c. Atterberg limits in accordance with ASTM D4318. Perform one test for every 1,000 cubic yards of the following types of materials to be incorporated into the Work:

suitable soil material, and soil structural fill.

d. Moisture/density relations for fill in accordance with ASTM D698, ASTM D1557, ASTM D4253, or ASTM D4254, as applicable. Perform one test for every 1,000 cubic yards of each material to be incorporated into the Work.

e. Moisture content of stockpiled or borrow material in accordance with ASTM D2216.

Perform one test for every 1,000 cubic yards of each material to be incorporated into the Work.

1.5 SUBMITTALS

A. Action Submittals: Submit the following:

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1. Shop Drawings:

a. Schedule (table or written narrative) indicating, for each specific area of the Work, type of fill materials proposed, together with indication of whether source of materials is onsite or borrow source. Identification of each type of material shall employ material names/designations identical to those in the Contract Documents.

2. Product Data:

a. Borrow Soil Materials: Name and address of Supplier of borrow soil materials, gradation, and Supplier’s certification that materials are sufficiently free of Constituents of Concern so that a Hazardous Environmental Condition will not be created or exacerbated. If no soil materials will be obtained from any borrow location, expressly so indicate to Engineer in writing.

b. Aggregate: Supplier’s published description of aggregate materials, including name and address of Supplier, certification of material’s compliance with AASHTO and state department of transportation standards, and gradation.

B. Informational Submittals: Submit the following:

1. Procedure Submittals:

a. Excavation plan indicating:

1) Excavation Method(s): Indicate high-level methods to be used for excavating, such as use of backhoe or other earth moving construction equipment, use of explosives in excavating (when allowed), trenchless excavating methods, micro-trenching, hydro-excavating (when allowed), air vacuum excavating (when allowed), or other.

Where different methods will be used, indicate locations of each in the Work.

Purpose of indicating high-level excavating methods is for Owner’s information regarding effect of excavating method on Owner’s or facility manager’s (if other than Owner) property and operations.

2) Copies of permits and approvals required for trenching, backfilling, and related earth Work, obtained from authorities having jurisdiction, including owners of affected utilities and transportation facilities, for excavation methods proposed.

b. Compaction procedure and compaction equipment proposed for use. Where different procedures or equipment will be used for compacting different types of material or at different locations at the Site, indicate where each procedure and equipment item will be used.

c. Engineer’s acceptance of excavation plan does not, in any way, modify Contractor’s sole responsibility for complying with the Contract Documents, construction means, methods, procedures, techniques, or sequences, and safety and protection measures incident thereto.

2. Quality Assurance Test Results Submittals:

a. Submit results of quality assurance testing performed in accordance with this Section’s

“Quality Assurance” Article, unless included as part of another submittal under this Section. Submit results for the following quality assurance testing:

1) Tests on materials from onsite and borrow sources.

2) Optimum moisture – maximum dry density curve for each type of fill material.

3. Field Quality Control Submittals:

a. Submit results of testing and inspection performed in accordance with the field quality control Article in Part 3 of this Section, including:

1) Indication of soil classification in accordance with ASTM D2487.

2) Field density testing.

3) Proctor Compaction Test to determine optimum moisture for soil and maximum dry density.

4. Qualifications Statements:

a. Quality assurance testing laboratory, when requested by Engineer.

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1.6 FIELD CONDITIONS

A. Existing Conditions:

1. Subsurface Conditions:

a. Subsurface Information: The Supplementary Conditions indicate information (if any) that is Technical Data on subsurface conditions at the Site. Such information and data are not intended as a representation or warranty of continuity of conditions between soil borings or test pits, nor of groundwater levels at dates and times other than date and time when measured, nor that purpose of obtaining the information and data were appropriate for use by Contractor. Owner and Engineer are not responsible for interpretations or conclusions drawn therefrom by Contractor.

b. Contractor’s Explorations: Soil borings and other exploratory operations may be made by Contractor, at no additional cost to Owner. Coordinate Contractor-performed test borings and other exploratory operations with Owner, utility owners, and owners of transportation facilities as appropriate. Perform such explorations without disrupting or otherwise adversely affecting operations of Owner and others.

2. Where subsurface conditions or locations of Underground Facilities and structures are unforeseen or differ substantively from that shown or indicated in the Contract Documents, comply with Contract requirements for giving notice and other actions.

3. Existing Structures and Underground Facilities:

a. The Contract Documents show or indicate certain structures and Underground Facilities adjacent to the Work. Such information was obtained from existing records and is not guaranteed to be correct or complete. Contractor shall explore ahead of the excavation to determine the exact location of all existing structures and Underground Facilities.

Existing structures and Underground Facilities shall be supported and protected from damage by Contractor. Immediately repair and restore existing structures and Underground Facilities damaged by Contractor without additional cost to Owner.

b. Movement or operation of construction equipment and machinery over Underground Facilities shall be at Contractor’s sole risk. When required by owner of the Underground Facility, prepare and submit to owner of such Underground Facility, and obtain their acceptance, of Contractor’s plan presenting Contractor’s analysis of the loads to be imparted during construction (including transient loading by construction equipment, machinery, and vehicles) and Contractor’s proposed measures to protect structures and Underground Facilities during the Work.

c. Acceptance of or approval by utility owner or Engineer of Contractor’s proposed evaluation and method(s) for protecting Underground Facilities in no way modifies or reduces Contractor’s sole responsibility for complying with the Contract Documents, means, methods, procedures, techniques, and sequences of construction, and the safety and protection measures incident thereto.

d. Coordinate with utility owners for shut off of services in active piping and conduits.

When required by utility owner, Owner will assist Contractor with utility owner notifications. Completely remove buried piping and conduits indicated for removal and not otherwise indicated as being abandoned or to remain in place.

e. In general, service lines and laterals to individual residences, businesses, buildings, and structures, are not shown; however, Contractor shall assume that a service exists for each utility owner to each residence, business, building, structure, and property.

f. Do not interrupt existing utilities serving facilities occupied and used by Owner or others, except when such interruption is indicated in the Contract Documents or when allowed in writing by Engineer after acceptable temporary utility services are provided by Contractor for the affected structure or property.

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PART 2 - PRODUCTS

2.1 MATERIALS

1. Provide granular under-slab fill under foundations, manholes, chambers, vaults, handholes, and similar Work unless other under-slab material is required by the Contract Documents.

2. ASTM C33/C33M gradation size no. 67, or other material acceptable to Engineer.

3. Material shall be uniformly-graded, washed, evenly graded mixture of crushed stone, or crushed or uncrushed gravel, free of organic and deleterious material, complying with the following:

a. 100 percent passing a 1.5-inch sieve.

b. Not more than five percent passing a no. 4 sieve.

B. Granular Structural Fill:

1. Granular structural fill, sometimes called “select granular fill”, is required for improving subgrade (after removal of unsuitable material), as backfill for excavations in areas that, after restoration, will be subject to vehicular traffic, and at other locations shown or indicated for such material in the Contract Documents.

2. Material shall be well-graded, crushed aggregate, free of organic and deleterious material.

C. Soil Structural Fill:

1. At Contractor’s option, soil structural fill may be low-volume change cohesive soil material or granular soil material.

2. Free of organic and deleterious matter, frozen material and debris.

3. Low-volume change cohesive soil material:

a. ASTM D2487 classification: CL-ML or CL.

b. Liquid limit: Less than 45.

c. Maximum plasticity index: 20.

4. Granular soil material:

a. ASTM D2487 classification: GW, GP, GM, GC, SW, SP, SM or SC.

5. Previously excavated materials complying with the Contract Documents requirements for soil structural fill may be used for soil structural fill.

6. When onsite materials are unsuitable for use as soil structural fill, provide granular structural fill or approved borrow material as soil structural fill. Prior to using borrow material as soil structural fill, furnish product data Submittal and quality assurance Submittal for proposed material and obtain Engineer’s approval and acceptance (as applicable) of the proposed material.

D. Suitable Soil Material as Non-Structural Fill:

1. Provide suitable soil material as fill for the Work, unless other material is required.

2. Material shall be:

a. Free of rock larger than three inches in any dimension, debris, waste, frozen materials, organic material, and other deleterious material.

b. ASTM D2487 classification: GW, GP, GM, GC, SC, SW, SP, SM, CL-ML or CL.

c. Liquid limit: Not greater than 45.

d. Plasticity index: not greater than 20.

3. Previously-excavated materials complying with the Contract Documents requirements for suitable soil material may be used for suitable soil material.

4. When onsite materials are unsuitable for use as suitable soil material, provide granular structural fill or soil structural fill or approved borrow material as suitable soil material. Prior to using borrow material as suitable soil material, furnish product data Submittal and quality assurance Submittal for proposed material and obtain Engineer’s approval and acceptance (as applicable) of the proposed material.

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E. Subbase Material:

1. Subbase material is granular material underlying pavement, sidewalks, and other surfaces expressly indicated in the Contract Documents.

2. Material shall be naturally or artificially-graded mixture of natural or crushed gravel, crushed stone, or natural or crushed sand. Slag is unacceptable.

F. Pipe Bedding Material:

1. Materials: Unless otherwise expressly required in the Contract Documents, pipe bedding material shall be crushed stone and gravel, free of: rock or gravel larger than one-inch in any dimension, debris, waste, frozen materials, organic material and other deleterious matter.

a. Materials shall be per Florida Department of Transportation standard.

2. Sand:

a. Where expressly required or allowed by the Contract Documents, provide sand as pipe bedding material.

b. Materials shall be per Florida Department of Transportation Standard.

c. Sand material, where used, shall consist of natural or manufactured granular material and shall contain no organic material.

d. Sand shall be non-plastic, when tested in accordance with ASTM D4318.

e. Gradation: 100 percent shall pass a no. 4 sieve and not more than five percent shall pass a No. 200 sieve.

G. Flowable Fill, also known as Controlled Low Strength Material (CLSM):

1. Unless expressly required otherwise by the Contract Documents, flowable fill may be used, at Contractor’s option (following Engineer’s approval), for backfilling in lieu of the following materials: granular structural fill, pipe bedding material, soil structural fill, suitable soil material used as non-structural fill.

2. Comply with Section 03 31 - Concrete Materials and Proportioning.

3. Material provided shall be excavatable by ordinary mechanical excavation equipment, such as backhoes.

2.2 SOURCE QUALITY CONTROL

A. Tests and Inspections at Source of Supply:

1. Perform quality assurance testing, and submit results to Engineer, in accordance with the “Quality Assurance” Article in Part 1 of this Section.

PART 3 - EXECUTION

3.1 EXAMINATION

A. Verification of Conditions:

1. Provide Engineer with sufficient notice and with means to examine areas and conditions under which trenching, backfilling, other related earth Work, and grading will be performed.

Engineer will advise Contractor in writing when Engineer is aware of conditions that may be detrimental to proper and timely completion of the Work. Do not proceed with the Work until unsatisfactory conditions are corrected.

2. This Article, however, in no way modifies or reduces Contractor’s sole responsibility for complying with the Contract Documents, for construction means, methods, procedures, techniques, and sequences, and for the safety and protection measures incident thereto.

3. Nothing in this Article, including action by Engineer or Resident Project Representative (if any), is for benefit of Contractor.

B. Installing the Work constitutes Contractor’s approval of underlying work, subgrades, and field conditions prevailing at the time of the Work.

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3.2 TEST PITS

A. Test Pits - General:

1. Test Pit Locations Not Shown or Indicated in the Contract Documents and Test Pits Not Part of a Dedicated Bid/Pay Item:

a. In advance of other construction, excavate test pits, make observations and measurements, and promptly fill test pits.

b. Purpose of test pits is to determine existing subsurface conditions and locations of

Underground Facilities and structures.

c. Perform all work required in connection with excavating, stockpiling, maintaining, temporarily supporting excavations, filling, and replacing pavement for test pits.

Contractor is responsible for the definite location of each existing Underground Facility involved within the area of excavation for the Work. Exercise care during such location work to avoid damaging and disrupting affected Underground Facility or structure.

Contractor is responsible for repairing, at Contractor’s cost, damage to Underground Facilities or structure caused during the Work.

B. Payment for Test Pits:

1. All payment for test pits shown or indicated in the Contract Documents will be part of the bid/pay item Contract Price.

C. Results of Test Pits:

1. Document results of all test pits excavated by Contractor.

2. Submit to Engineer written results of test pits expressly required by the Contract Documents or directed by Engineer. Furnish such Submittal within three days of excavation of associated test pit, unless Engineer allows more time. When Engineer requests written results of test pits performed for Contractor’s own use, promptly furnish such information as Informational Submittal.

3. Required documentation of test pits shall include:

a. Identification of Project, Site, and Contractor.

b. Date and time of test pit excavation, indication of weather conditions, and names of personnel present and employer of each.

c. Detailed description of location of test pit, including, where necessary, measurements to landmarks shown on the Drawings. Where appropriate, include sketch of location from the Drawings.

d. Indication of approximate dimensions of test pit, including length, width, and depth.

e. Verbal (written) description of observed subsurface conditions, including apparent strata, rock (if any), groundwater conditions, and approximate depth at which each was observed.

f. Verbal (written) description of unusual conditions observed, including potential existence of Hazardous Environmental Condition, if any. Include pertinent data, such as readings from instrumentation used.

g. Description and sketch, with appropriate dimensions, of Underground Facilities and structures in the test pit. Sketches shall be clearly legible with clear, well-written annotations and dimensions.

h. Other pertinent information and data from observations made while test pit was open.

i. Brief written description of backfilling and restoration of test pit, including time operations were completed.

3.3 PREPARATION

A. Site Preparation:

1. Comply with Section 31 10 00 - Site Clearing.

2. Comply with this Section’s “Erosion and Sediment Control During Construction” Article.

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B. Dust Control:

1. Relative to controlling dust during construction, comply with Section 01 57 05 - Temporary Controls and Section 01 74 00 - Cleaning.

C. Maintenance and Protection of Traffic:

1. Comply with Section 01 55 26 - Traffic Control.

3.4 EROSION AND SEDIMENT CONTROLS DURING CONSTRUCTION

A. Temporary Erosion and Sediment Controls – General:

1. Provide temporary erosion and sediment controls in accordance with Section 01 57 05 - Temporary Controls, and other requirements of the Contract Documents.

2. When applicable, also comply with requirements of the erosion and sediment control plan approved by authorities having jurisdiction and the Project’s storm water pollution prevention plan and permit, if any.

3.5 EXCAVATION

A. Excavation – General:

1. Perform all excavation Work, including trenching and backfilling, required to complete the Work as shown, specified, and required. Excavating Work includes removing, handling, and proper disposal of earth, sand, clay, expansive-type soils, other unsuitable soil materials, gravel, hardpan, soft, weathered or decomposed rock, concrete and masonry (reinforced or unreinforced), pavements, rubbish, debris, stumps, and other materials, regardless of moisture content, within the excavation limits.

2. Trenching and backfilling Work shall comply with the Contract Documents, including required grades, elevations, general dimensions, and alignment shown or indicated on the Drawings including cuts and fills, as applicable.

3. Protect existing buildings and structures against undermining and destabilization. If adjacent trenching affects foundations of one or more buildings or structures, promptly advise Engineer in writing.

4. If unsuitable material and obstructions are encountered during excavation, remove material and replace as directed by Engineer.

B. Excavation Methods:

1. Traditional Excavation Methods: Excavation via traditional methods, such as backhoe, bulldozer, other earth moving construction equipment or machinery, or excavation using hand tools, is acceptable for all excavating Work

2. Use of Explosives:

a. Use of explosives is not allowed.

3. Micro-trenching: Installation of buried utilities using micro-trenching equipment and techniques is acceptable when the associated Underground Facility is of a size and depth appropriate for such construction method. Submit to Engineer request for interpretation or clarification for requirements for resin backfilling of micro-trenches. Engineer will issue such requirements via Field Order.

4. Trenchless: Where Contractor proposes trenchless construction techniques, such as directional drilling, micro-tunneling, or others, comply with the Contract Documents regarding such construction methods. When the Contract Documents do not include requirements for the proposed trenchless construction method, submit to Engineer request for interpretation or clarification to obtain appropriate requirements, which will be issued via appropriate Contract modification.

5. Hydro-excavating (also known as Hydro-Vacuum Excavating):

a. Hydro-excavating is acceptable for all excavating Work

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b. Avoid creating nuisances, unsafe conditions, and inconvenience to Owner, facility manager, owners and occupants of adjacent property, and the public when hydro-excavating is allowed and used.

6. Air Vacuum Excavating:

a. Air vacuum excavating is acceptable for all excavating Work

b. Avoid creating sandblasting outside of excavations, dust emissions, other nuisances, unsafe conditions, and inconvenience to Owner, facility manager, owners and occupants of adjacent property, and the public when air vacuum excavating is allowed and used.

C. Excavation Protection:

1. Provide excavation protection system(s) in accordance with Laws and Regulations to prevent injury to persons and property, including Underground Facilities.

2. Provide safe access to excavations, including emergency exit, and safe access for construction equipment and machinery, where applicable, in accordance with laws and Regulations.

D. Excavations for Manholes, Chambers, and Vaults:

1. Refer to this Section, Section 01 22 00 - Measurement and Payment, and applicable details (if any) on the Drawings for requirements on excavation pay limits for manholes, chambers, vaults, and similar items.

2. Elevation of bottom of manholes, chambers, and vaults may be changed only via duly issued Contract modification. Such modifications may be directed by Engineer to ensure a stable bearing surface. Elevations of piping, conduit, and similar other Underground Facilities shall be as shown or indicated on the Contract Documents.

3. Extend excavations sufficiently on each side of manholes, chambers, vaults, or similar construction only as necessary for installing precast concrete structures and appurtenances, including temporary supports of excavations, observation and inspection of the Work, and safe sloping of sides of excavations, as necessary.

E. Subgrades – General:

1. Provide firm, dense, thoroughly compacted, consolidated subgrades, free of mud, muck, and other soft and unsuitable materials. Subgrades shall remain firm and intact under all construction operations. Reinforce subgrade by providing granular structural fill on subgrades that are otherwise solid but become soft or muddy on top due to construction operations. Finished elevation of stabilized subgrades shall not be above subgrade elevations shown on the Drawings, unless bottom of trench is rock below required bottom elevation of pipe, manhole, chamber, or vault, and above required bottom of excavation elevation.

2. If, in Engineer’s opinion, subgrade becomes soft, muddy, or both, because of construction delays, failure to dewater properly, or other cause within Contractor’s control, excavate subgrade to firm material, trim the subgrade, and backfill with granular structural fill material at Contractor’s cost.

3. Remove unsuitable subgrade materials below foundations. Limits of required removal of unsuitable material, when not otherwise expressly shown or indicated in the Contract Documents, shall be outside exterior limits of foundations around perimeter of manhole, chamber, vault, or similar item, by not less than the greater of the following horizontal distances:

a. Distance equal to depth of required removal of unsuitable material, below bottom of foundations.

b. Three feet.

c. As directed by Engineer, in consultation with geotechnical engineering consultant (if any).

4. Preparation of Subgrades for Subsequent Work:

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a. Level off subgrades to receive foundations or compacted fill.

b. Where subgrades are to receive subsequent fill or manholes, chambers, vaults, or similar items, remove loose materials and bring subgrades into compliance with the Contract Documents.

c. Where compacted fill material is required to bring subgrade up to underside of construction, scarify existing subgrade upon which fill material will be placed to depth of six inches and then compact to density required in this Section before fill material is placed thereon.

d. Do not excavate lower than required for buried piping or foundations, unless directed otherwise by Engineer.

e. Where excavation extends below required elevation without authorization, promptly advise Engineer and remedy unauthorized excavation in accordance with the Contract Documents. Corrections may include:

1) Under soil-supported foundations or soil-supported retaining walls:

a) Filling entire vertical distance between excavated subgrade and material required under foundation or other structure with compacted granular structural fill.

b) Concrete fill is acceptable for bringing elevations to proper position.

2) For locations other than those indicated above including slabs-on-grade:

a) Backfill and compact unauthorized excavations as indicated for authorized excavations of same classification, unless otherwise directed by Engineer.

3) Contractor is not eligible for change in Contract Price or Contract Times for remedying unauthorized excavations.

5. Evaluation and Protection of Subgrade:

a. Advise Engineer as soon as excavation is completed for Engineer’s observation of subgrades and, where necessary or required, inspection and testing of subgrades.

b. If Engineer determines that bearing materials at required subgrade elevations are unsuitable, provide subgrade stabilization as indicated in this Article.

c. Do not commence further construction until subgrade under compacted fill material, under foundations and retaining walls is acceptable (in accordance with the Contract Documents) to Engineer, who may consider results of required testing, and who may elect to consult with geotechnical consultant (if any).

d. Engineer shall have sufficient opportunity to observe subgrade, after successful completion of tests and inspections required by the Contract Documents.

e. Place fill material and perform subsequent construction after subgrade is acceptable in accordance with the Contract Documents.

f. Protect subgrade from becoming loose, wet, frozen, or soft due to weather, construction operations, or other reasons.

6. Subgrade stabilization:

a. If subgrade under foundations or fill material, is frozen, loose, wet, or soft before construction is placed thereon, remove frozen, loose, wet, or soft material and replace with approved compacted material as directed by Engineer, who may consult with geotechnical consultant.

b. Loose, wet, or soft materials, when approved by Engineer, may be stabilized by a compacted working mat of well graded crushed stone.

c. Stabilization shall be in accordance with the Contract Documents. Where the Contract Documents do not address subgrade stabilization, promptly submit to Engineer written request for clarification or interpretation, or other written instrument in accordance with the Contract Documents. In such event, do not proceed until response is obtained from engineer.

F. Pipe Trench Preparation:

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1. Not more than 150 feet of trench may be opened in advance of installing pipe in trench.

2. Trench width shall be minimized to greatest extent practical, and shall comply with the following:

a. Trench width shall be sufficient to provide space for installing, jointing and inspecting piping. The Drawings show additional requirements for trenches. In no case shall trench be wider at top of pipe than pipe barrel’s outside diameter (OD) plus two feet, unless otherwise shown or indicated.

b. Enlargement of trench width at pipe joints may be made when required and approved by Engineer.

c. For excavating and backfilling for manholes, chambers, and vaults associated with buried piping, excavation at widest point of manhole, chamber, or vault shall be not wider than two feet greater than widest outside dimension (including bottom footings or flanges, if any, of precast concrete structures) of the associated manhole, chamber, or vault.

d. Trench width shall be sufficient for Contractor’s means of temporarily supporting the excavation and dewatering.

e. Trench width shall be sufficient to allow thorough compaction of fill adjacent to bottom half of pipe.

f. Do not use construction equipment or machinery that necessitates trench to be excavated to excessive width.

3. Depth of trench shall be as shown or indicated in the Contract Documents. If required and approved by Engineer in writing (such as a duly issued Contract modification), depths may be revised.

4. Where Engineer considers existing subgrade (beneath intended bedding material) unsuitable, remove and replace such unsuitable material with granular structural fill material for full width of trench, down to suitable material.

G. Freeze Protection:

1. Do not place foundations or fill material on frozen subgrade.

2. When freezing temperatures are expected, based on widely recognized, reputable source for weather forecasts at or near the Site, do not excavate to full depth indicated, unless foundations or fill material can be placed immediately after excavation has been completed and is acceptable in accordance with the Contract Documents.

3. Protect from freezing excavation, subgrade, and fill materials when subsequent Work thereon is delayed.

H. Construction Traffic on Soils:

1. Furnish and use appropriate backhoe or other low-contact pressure equipment to remove existing materials.

2. Minimize construction traffic on existing materials and saturated soils and avoid soil disturbance.

3. Repair disturbed subgrade materials prior to performing subsequent Work. Remedial work shall be in accordance with the Contract Documents. When not addressed in the Contract Documents, remedial Work shall be as directed by Engineer via appropriate Contract modification.

4. Allow only minimal foot traffic on bearing soils prepared for subsequent installation of fill or foundations.

3.6 FILLING AND COMPACTING

A. Filling and Compacting – General:

1. Provide and compact all fill required for the finished grades as shown and as indicated in this Section.

B. Place fill as promptly as progress of the Work allows, but not until completing the following:

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1. Obtaining Engineer’s concurrence, after observation by Engineer or Resident Project Representative (if any) of construction below finish grade, including removal of trash and debris from excavations, waterproofing (where required), and related Work.

2. Successful completion of required field quality control activities for Work that will be covered or concealed by filling, including field quality control testing of buried piping, conduits that will convey fluid or gas, and exfiltration testing (where performed or required) of manholes, chambers, vaults, and similar items. For manholes, chambers, and vaults, where infiltration testing or vacuum testing is performed or required, such testing may be performed following backfilling.

3. Completion of proper documentation of as-constructed conditions and existing conditions (such as locations of Underground Facilities) in accordance with Section 01 78 39 - Project Record Documents.

4. Removal of temporary supports of excavations.

5. Remove fill that includes organic materials or other unacceptable material and replace with fill material complying with the Contract Documents.

C. Placement – General:

1. Place fill to the grades shown or indicated. Bring up evenly on all sides fill around manholes, chambers, vaults, and similar items, and Underground Facilities.

2. Management of Moisture Content:

a. Place fill materials at moisture content and density as indicated in this Article’s requirements on compaction density. Prior to placing fill material, optimum moisture and maximum density properties for proposed material shall be obtained from Engineer, who may consult with geotechnical consultant, if any. Furnish and use construction equipment and machinery capable of adding measured amounts of water to fill materials to bring fill materials to a condition within required moisture content range.

Control moisture for each lift necessary for required compaction.

b. Furnish and use construction equipment and machinery capable of discing, aerating, and mixing fill materials to ensure reasonable uniformity of moisture content throughout fill materials, and to reduce moisture content of borrow materials by air drying, when necessary.

c. When subgrade or fill materials requires moisture-conditioning before compaction, fill material shall be sufficiently mixed or worked on the subgrade to ensure uniform moisture content throughout the lift of material to be compacted.

d. Materials at moisture content in excess of specified limit shall be dried by appropriate means, such as aeration or stockpiling for gravity drainage and air drying.

3. Compaction:

a. Compaction Equipment:

1) Perform compaction with construction equipment and machinery suitable for the type of fill material placed. Unless otherwise required, compact cohesive soils using sheepsfoot compactor, and compact granular materials using pneumatic rollers, vibrators, or other construction equipment or machinery to obtain required density.

2) Select and use equipment capable of providing the minimum density required in the Contract Documents.

3) Use light compaction equipment and machinery, with equipment or machinery gross weight not exceeding 7,000 pounds within horizontal distance of 10 feet from the wall of completed, below-grade manholes, chambers, vaults, and similar items, and walls of adjacent buildings or structures.

4) Furnish and use construction equipment and machinery capable of compacting in restricted areas next to structures and around piping and Underground Facilities.

b. Compaction Test Area:

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1) Effectiveness of construction equipment and machinery selected by Contractor for compacting, shall be tested at start of compacted fill Work by constructing a small section of fill within the area where fill will be placed.

2) If tests on the test section of fill indicate that required compaction is not obtained, do one or more of the following: increase the quantity of coverages, decrease the lift thicknesses, or use different compactor equipment or machinery.

4. Placement of Lifts and Compaction:

a. Place fill materials in horizontal, loose lifts, not exceeding specified thickness prior to compacting.

b. Place fill in manner ensuring uniform lift thickness after placing.

c. Preparation of surfaces for placement of fill:

1) Before commencing placing of fill, scarify underlying material to depth of six inches.

2) Where ground surface is steeper than one vertical to four horizontal (“1V:4H”), plow surface to bench and break up surface so that fill material will bind with existing surface. For slopes steeper than 1V:4H and less than 1V:1.5H, bench shall be six feet wide. For slopes steeper than or equal to 1V:1.5H and less than 1V:0.5H, bench shall be four feet wide.

d. Mechanically compact each lift, by not less than two complete coverages of compactor.

One coverage is defined as the conditions reached when all portions of the fill lift have been subjected to the direct contact of compactor’s compacting surface.

e. Compaction of fill materials by inundation with water is unacceptable.

5. Restrictions:

a. Do not place fill materials when standing water is present on surface of area where fill will be placed.

b. Do not compact fill when standing water is present on the fill to be compacted.

c. Do not place or compact fill in frozen condition or on top of frozen material.

d. Fill containing organic or deleterious materials or other unacceptable material previously described shall be removed and replaced prior to compaction.

6. If required densities are not obtained because of improper control of placement or compaction procedures, or because of inadequate or improperly functioning compaction equipment or machinery, perform all work necessary to provide required densities. Such work shall include, at no additional cost to Owner, complete removal of unacceptable fill areas and replacement and re-compaction until acceptable fill is provided.

7. Repair, at Contractor’s cost, observed or measured settlement. Make repairs and replacements as necessary and required within 30 days after being so advised by Engineer, unless more-timely action is necessary to avoid or reduce the potential for safety hazards or damage to property.

D. Fill Placed in Pipe Trenches:

1. Piping trenches may be backfilled prior to testing of piping, unless nature of test requires observation of pipe or manholes, chambers, vaults, or similar items during testing. Do not construct building or structure over piping until piping has been successfully tested and passed.

2. Pipe Bedding: Pipe bedding material shall be as follows:

a. Unless otherwise shown or indicated, install other types of buried piping on not less than six-inch layer of aggregate pipe bedding material underneath piping.

b. Pipe bedding material shall extend upward from elevation required immediately above to horizontal centerline of associated buried piping.

c. Pipe bedding material shall be spread and the surface graded to provide a uniform and continuous support beneath piping at all points between bell holes or pipe joints.

d. Install initial layer of pipe bedding…