1 Scope
NOTE This specification covers the materials, execution, testing, and quality control for all earthwork operations on the project site. (1.1)
NOTE Earthwork is the first construction scope to begin and the last to be fully closed out — it directly conditions every subsequent scope, from foundations and utilities to paving and landscaping. (1.2)
NOTE Errors in earthwork, particularly inadequate compaction or failure to honor geotechnical recommendations, propagate forward through the project as structural distress, settlement, utility misalignment, pavement failure, and warranty claims. (1.3)
NOTE The investment in doing earthwork correctly is always less than the cost of remediation. (1.4)
NOTE This standard addresses site clearing and demolition of existing improvements, cut and fill grading operations, excavation by type and purpose, classification of materials encountered, fill and backfill materials and placement, compaction requirements, subgrade preparation, groundwater management and dewatering, temporary excavation support, and erosion and sediment control throughout the construction period. (1.5)
1.6 All work shall conform to the recommendations of the geotechnical investigation report prepared for this project.
1.7 In cases of conflict between this standard and the geotechnical report, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE The Contractor shall recognize that the geotechnical investigation report is based on a limited number of borings and test pits that characterize but do not fully describe the subsurface, and that actual conditions encountered may differ from those reported. (1.8)
1.9 The Contractor shall promptly notify the Engineer of Record of any differing site condition that materially affects work under this specification, including unexpected groundwater, rock, soft or organic soils, buried utilities, obstructions, or contaminated materials not identified in the geotechnical report.
1.10 The Contractor shall coordinate work under this specification with Cast In Place Concrete for foundation bearing surface preparation and concrete placement over prepared subgrades, with Below Grade Waterproofing for backfill restrictions adjacent to waterproofed foundation walls, with Aggregate Base Course for subbase and base course work under pavements, and with Storm Drainage for pipe trench requirements and inlet protection. 2 Referenced Standards
2.1 Equipment, materials, testing, and execution shall comply with the latest adopted edition of the following standards.
2.2 Where project documents, adopted codes, and referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| ASTM D698 |
Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft³) |
| ASTM D1557 |
Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft³) |
| ASTM D1556/D1556M |
Standard Test Method for Density and Unit Weight of Soil in Place by Sand-Cone Method |
| ASTM D2167 |
Standard Test Method for Density and Unit Weight of Soil in Place by the Rubber Balloon Method |
| ASTM D2216 |
Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass |
| ASTM D2487 |
Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) |
| ASTM D2488 |
Standard Practice for Description and Identification of Soils (Visual-Manual Procedures) |
| ASTM D4318 |
Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils |
| ASTM D6938 |
Standard Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth) |
| ASTM D7928 |
Standard Test Method for Particle-Size Distribution (Gradation) of Fine-Grained Soils Using the Sedimentation (Hydrometer) Analysis |
| ASTM C136/C136M |
Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates |
| IBC Chapter 18 |
Soils and Foundations (International Building Code, currently adopted edition) |
| OSHA 29 CFR 1926 Subpart P |
Excavations (Safety and Health Regulations for Construction) |
| EPA NPDES CGP |
Construction General Permit (National Pollutant Discharge Elimination System) |
| AASHTO T 99 |
Standard Method of Test for Moisture-Density Relations of Soils Using a 2.5-kg Rammer and a 305-mm Drop |
| AASHTO T 180 |
Standard Method of Test for Moisture-Density Relations of Soils Using a 4.54-kg Rammer and a 457-mm Drop |
3 Submittals
3.1 Action Submittals
3.1.1 The Contractor shall submit the following for the Engineer of Record's review prior to beginning work:
- Geotechnical investigation report (if not included in the contract documents): the Contractor shall confirm receipt of the current geotechnical report and shall flag any conflicts between the report and the contract documents before beginning earthwork
- Excavation safety plan prepared or reviewed by a competent person as defined in OSHA 29 CFR 1926 Subpart P, describing the method for protecting workers in every excavation exceeding 5 feet in depth, including the classification of soils, the selected protective system, and the means of access and egress
- Shoring and sheeting design where a designed system is required: engineer-stamped drawings and calculations for all temporary support systems that cannot be designed from OSHA Appendix B tables
- Dewatering plan where groundwater is anticipated at or near excavation depth: describe the proposed method, equipment, discharge point, and permits; include calculations for anticipated inflow where the system is designed
- Temporary erosion and sediment control plan conforming to the project SWPPP, showing the location and type of all BMPs, sequencing with grading activities, and maintenance protocol
- Imported fill material certifications: gradation analysis and Proctor test results for each proposed import source, confirming compliance with material requirements of this specification; materials shall not be imported until approved
☐ Geotechnical investigation report confirmation / conflict log
☑ Excavation safety plan (OSHA Subpart P competent person)
☐ Shoring / sheeting design drawings and calculations (where applicable)
☐ Dewatering plan and discharge permits (where applicable)
☐ Erosion and sediment control plan / SWPPP conformance
☐ Imported fill material certifications and Proctor test data
3.1.2 Excavation and fill operations shall not proceed on any portion of the site until the submittals relevant to that portion are reviewed and returned.
3.1.3 Submittal review does not relieve the Contractor of responsibility for compliance with contract documents.
3.2 Closeout Submittals
3.2.1 Prior to substantial completion the Contractor shall provide the following:
- Field testing reports for all compaction testing, including test locations, test method, lift number, tested dry density, moisture content, percent compaction, and pass/fail against the applicable criterion; reports shall be signed by the testing technician
- As-built grading survey confirming that final grades conform to the drawings within the tolerances specified herein
- Certification from the geotechnical engineer of record (or the Owner's special inspector) that earthwork operations were observed and conform to the geotechnical report recommendations and this specification
- Erosion and sediment control closeout documentation: confirmation that all temporary BMPs have been removed, permanent stabilization has been established, and the site is in compliance with permit requirements
☑ Field compaction testing reports (signed by technician)
☑ As-built grading survey
☑ Geotechnical engineer of record earthwork conformance certification
☑ Erosion and sediment control closeout documentation
4 Quality Assurance
4.1 Geotechnical Engineer of Record
4.1.1 The Owner shall retain a licensed geotechnical engineer of record to provide construction observation and materials testing services for earthwork.
4.1.2 The geotechnical engineer shall observe subgrade conditions at the base of every foundation excavation before concrete or fill is placed.
4.1.3 The geotechnical engineer shall observe proof-rolling operations.
4.1.4 The geotechnical engineer shall evaluate any differing site condition reported by the Contractor.
4.1.5 The geotechnical engineer shall interpret the project geotechnical report in light of actual conditions.
4.1.6 The geotechnical engineer shall direct adjustments to materials or procedures when warranted.
4.1.7 The geotechnical engineer's authority to halt earthwork operations that do not conform to the recommendations of the geotechnical report is binding on the Contractor.
4.2 Competent Person
4.2.1 The Contractor shall designate a competent person as defined in OSHA 29 CFR 1926 Subpart P to be present at all excavation work exceeding 5 feet in depth.
4.2.2 The competent person shall classify soils, evaluate excavation stability, inspect the excavation daily and after every rain event or other occurrence that could affect stability, and direct immediate corrective action when hazardous conditions are observed.
4.2.3 The Contractor shall not substitute personnel without ensuring that the replacement meets the competent person qualification.
4.3 Special Inspection
4.3.1 Where the adopted building code or the structural drawings require special inspection for earthwork, the Owner shall retain a special inspector approved by the Authority Having Jurisdiction.
4.3.2 The special inspector shall perform periodic and continuous observation as required by the inspection program, document observations and test results, and report non-conformances to the Owner and to the Engineer of Record.
4.3.3 Special inspection under the building code does not relieve the Owner's geotechnical engineer of record of the separate obligation described above.
4.4 Pre-Construction Conference
4.4.1 Prior to beginning earthwork operations the Contractor shall participate in a pre-construction conference attended by the Contractor's superintendent responsible for earthwork, the Owner's geotechnical engineer of record, the Owner's special inspector, and the Engineer of Record.
4.4.2 The conference shall review the geotechnical report recommendations, the compaction requirements and testing program, the excavation safety plan, the dewatering plan, the erosion and sediment control plan, the requirements for dealing with differing site conditions, and the lines of communication for field decisions.
4.5 Testing Frequencies
4.5.1 Compaction testing frequencies shall conform to the geotechnical engineer's recommendations.
4.5.2 In the absence of project-specific direction, minimum testing frequencies shall be as follows: one test per 2,500 square feet of fill surface per lift for areas under footings, slabs, and pavements; one test per 100 linear feet of trench per lift for utility trenches; and one test per 500 square feet of fill surface per lift for general site grading not within a building footprint.
○ ASTM D698 (Standard Proctor — 12,400 ft-lbf/ft³)
● ASTM D1557 (Modified Proctor — 56,000 ft-lbf/ft³)
Nuclear gauge per ASTM D6938
Sand cone per ASTM D1556/D1556M
Rubber balloon per ASTM D2167
As directed by geotechnical engineer
4.5.3 The geotechnical engineer shall increase testing frequency in areas showing variability or failing tests.
4.5.4 Modified Proctor (ASTM D1557) shall be used for structural fill under foundations, floor slabs, and pavements, and for all trench backfill under or adjacent to structures.
4.5.5 Standard Proctor (ASTM D698) may be used for general site grading, landscaped areas, and non-structural fill remote from buildings and utilities.
NOTE When in doubt, use Modified Proctor — specifying the wrong test method is one of the most common earthwork errors, and a compaction result referenced against the wrong Proctor value is meaningless. (4.5.6)
NOTE The nuclear gauge method (ASTM D6938) is the standard production testing method because it is fast and non-destructive, allowing the same location to be re-tested after additional compaction effort if the first test fails; the sand cone method (ASTM D1556/D1556M) is the reference method for calibration and for locations where nuclear gauge use is restricted or impractical. (4.5.7)
4.5.8 The testing technician shall perform gauge count standard checks at the beginning and end of each testing session in accordance with ASTM D6938.
5 Soil Materials and Classification
5.1 Unified Soil Classification System
5.1.1 All soils encountered during excavation and all imported fill materials shall be classified in accordance with ASTM D2487, using the Unified Soil Classification System (USCS).
5.1.2 Visual identification in the field shall conform to ASTM D2488.
5.1.3 Where the geotechnical engineer determines that laboratory testing is needed to confirm field classification, tests shall include gradation per ASTM C136/C136M and ASTM D7928, and Atterberg limits per ASTM D4318.
5.1.4 USCS classification governs the acceptability of materials for specific fill applications as described herein.
5.1.5 The USCS designation shall be recorded on all field logs, boring logs, and test pit logs.
NOTE It is not sufficient to describe soils generically as "good," "bad," or "clay" — the USCS symbol (GW, GP, GM, GC, SW, SP, SM, SC, ML, CL, MH, CH, OL, OH, PT) provides a precise, universally understood language that carries information about drainage, compressibility, and suitability for specific applications. (5.1.6)
5.2 Classification of Materials for Excavation Payment
5.2.1 For payment and excavation planning purposes, materials encountered shall be classified as soil, soft rock / rippable rock, rock, or unsuitable material.
○ Blast (where permitted by local ordinance)
○ Hydraulic breaker / hoe-ram
○ Mechanical ripping
● Not anticipated — confirm with geotechnical engineer if encountered
5.2.2 The Contractor shall notify the Engineer of Record when material of a different classification than anticipated is encountered, before changing excavation methods.
NOTE Soil is naturally occurring or previously placed earth material that can be excavated with conventional earthmoving equipment (hydraulic excavators, dozers, motor graders, scrapers) without blasting or special treatment, and includes clay, silt, sand, gravel, and mixtures thereof, and previously placed fill. (5.2.3)
NOTE Soft rock / rippable rock is material that cannot be efficiently excavated with conventional earthmoving equipment but can be broken and removed by ripping with a heavy dozer-mounted ripper, or by hoe-ramming, including weathered or highly fractured rock, shale, hardpan, cemented gravels, and caliche. (5.2.4)
5.2.5 Classification of soft rock / rippable rock requires judgment by the geotechnical engineer based on observed seismic velocity, rock quality designation, and equipment performance.
NOTE Rock is solid material of mineral origin that cannot be excavated by ripping and requires drilling and blasting, hydraulic breaking, or other special methods for removal. (5.2.6)
5.2.7 Classification as rock shall be confirmed by the geotechnical engineer.
NOTE Unsuitable material is material that is unacceptable as a foundation bearing surface or as fill regardless of classification, including organic soils, topsoil, peat and muck, material with organic content by weight greater than 3 percent, frozen material, materials with liquid limit greater than 50 or plasticity index greater than 25 (unless specifically evaluated by the geotechnical engineer for a particular application), and materials with a swell potential that exceeds the bearing capacity design assumptions. (5.2.8)
5.3 Topsoil
NOTE Topsoil is the upper zone of naturally occurring soil containing organic matter, root systems, and biological activity. (5.3.1)
5.3.2 Topsoil shall be stripped from all areas to be occupied by fills, structures, pavements, and utility trenches.
5.3.4 Stripped topsoil shall be stockpiled separately from other excavated material for later use in landscaping and permanent vegetative stabilization, unless the geotechnical report indicates that site topsoil is unsuitable for reuse.
5.3.5 Topsoil stockpiles shall be located outside of fill areas and drainage swales, protected from erosion with perimeter silt fence, and seeded or covered if stockpiled for more than 30 days.
6 Site Clearing and Preparation
6.1 Clearing Limits
● Protective fencing at drip line — all designated trees
○ Protective fencing at drip line plus root pruning where excavation approaches protected zones
○ Not applicable — no trees designated for preservation
6.1.2 The Contractor shall stake clearing limits before beginning work.
6.1.3 The Contractor shall protect trees and vegetation designated for preservation with protective fencing installed at the drip line.
6.1.4 No equipment shall operate, no material shall be stockpiled, and no soil shall be compacted within the drip line of trees designated for preservation.
6.2 Demolition of Existing Improvements
6.2.1 Existing structures, pavements, curbs, walks, underground utilities, and other improvements within the work area shall be demolished and removed as shown on the drawings and as required for the work.
● Not permitted — remove all demolished concrete from site
○ Permitted in designated non-structural areas only — with Engineer of Record approval
6.2.2 The Contractor shall verify the locations of all underground utilities before demolition begins, using utility locates (one-call) and hand-digging as required within tolerance zones.
6.2.3 Existing underground storage tanks, septic systems, wells, and similar structures shall be decommissioned and removed in accordance with applicable regulations before earthwork proceeds.
6.2.4 The Contractor shall notify the Owner immediately if any previously unidentified underground storage tank or regulated structure is discovered.
6.2.5 Demolished concrete and masonry shall be removed from the site.
6.2.6 Concrete rubble shall not be used as fill unless specifically approved in writing by the Engineer of Record, limited to applications where the material can be adequately compacted and tested, and prohibited beneath buildings and slabs.
6.3 Subsurface Obstruction Discovery
6.3.1 The Contractor shall immediately notify the Owner and Engineer of Record upon discovery of any subsurface obstruction, buried structure, contaminated material, or other condition not shown on the contract documents.
6.3.2 Work in the affected area shall be suspended until the Engineer of Record issues written direction.
6.3.3 The Contractor shall not remove, disturb, or backfill around any discovered condition pending direction, except as required for immediate safety.
7 Excavation
7.1 General Excavation Requirements
7.1.1 Excavation shall be performed to the lines, grades, and dimensions shown on the drawings or directed by the Engineer of Record, with a tolerance of plus or minus 0.10 foot vertically for unformed excavation unless otherwise noted.
7.1.2 Excavated material suitable for reuse as structural fill shall be stockpiled separately from unsuitable material and protected from contamination, precipitation, and excessive drying.
7.1.3 All excavated material not to be reused shall be removed from the site and legally disposed.
7.1.4 The Contractor shall maintain all excavations in a dry condition and in a stable configuration.
7.1.5 Standing water shall not be permitted in excavations at the time fill or concrete is placed.
7.1.6 The bottom of all excavations shall be observed by the geotechnical engineer of record before placing fill, concrete, or other materials.
7.1.7 The Contractor shall not proceed past the geotechnical engineer's observation without written authorization.
7.2 Mass Grading and Cut Excavation
NOTE Mass grading operations remove soil and rock from areas to be lowered in elevation to achieve design grade, or strip and stockpile topsoil, or provide material for placement as fill elsewhere on the site. (7.2.1)
1.5H:1V — Type A soils (geotechnical confirmation required)
1H:1V — Type B soils
0.5H:1V — Type C soils
Per geotechnical engineer — site-specific analysis
Per drawings
7.2.2 Cut areas shall be shaped to drain away from any exposed subgrade.
7.2.3 Where cut slopes are required, temporary and permanent slope angles shall conform to the geotechnical report recommendations.
7.2.4 Temporary cut slopes shall be classified and designed in accordance with OSHA 29 CFR 1926 Subpart P, Appendix B.
NOTE OSHA soil type classifications (Type A, B, C) are distinct from USCS classifications and are used specifically for determining safe temporary slope angles and excavation support requirements. (7.2.5)
7.2.6 The competent person shall determine the OSHA soil classification for every excavation based on visual and manual tests described in OSHA Appendix A.
7.2.7 Wet or overloaded cut slopes that begin to move or ravel shall be immediately brought to the attention of the competent person and the geotechnical engineer.
7.2.8 The Contractor shall not allow personnel to work below an unstable cut slope.
7.3 Structural Excavation
NOTE Structural excavation is excavation performed to create space for foundations, pits, grade beams, retaining walls, and similar structures. (7.3.1)
Lean concrete fill to design grade (minimum 2,000 psi)
Compacted structural fill to design grade (geotechnical engineer approval required)
Geotechnical engineer to evaluate and direct — case by case
7.3.2 Structural excavation shall be performed to the neat lines and grades shown on the structural drawings, plus working space required for forming and waterproofing.
7.3.3 Final trimming of the bearing surface at the bottom of structural excavation shall be performed by hand or by a smooth-bucket excavator, removing no more than necessary to achieve a clean, undisturbed bearing surface at the design elevation.
NOTE Over-excavation of foundation bearing surfaces is a common and costly error — once the bearing stratum is loosened or saturated, it cannot be simply re-compacted to the same condition. (7.3.4)
7.3.5 If the bearing surface is inadvertently over-excavated, or if soft, loose, or otherwise unsuitable material is encountered at the bearing elevation, the geotechnical engineer shall be consulted before proceeding, and remedial options may include further over-excavation and replacement with lean concrete or compacted structural fill, subgrade improvement, or foundation redesign.
7.3.6 The bearing surface at the bottom of structural excavation shall be proof-rolled or probed by the geotechnical engineer before any concrete or fill is placed.
7.3.7 Soft, yielding, or pumping areas shall be undercut and replaced.
7.3.8 The Contractor shall provide the geotechnical engineer at least 24 hours notice before each bearing surface will be ready for observation.
7.4 Trench Excavation
NOTE Trench excavation serves utility installation, including water supply, sanitary sewer, storm drainage, electrical conduit, gas, and communications. (7.4.1)
Undisturbed native soil shaped to pipe O.D.
Granular bedding material — minimum 4 in. depth below pipe
Concrete cradle
Per drawings — utility drawings
7.4.2 Trench excavation shall conform to the alignment, depth, grade, and bedding requirements shown on the utility drawings.
7.4.3 Trench width shall be the minimum necessary for safe worker access and utility installation and bedding placement, but not less than the pipe outside diameter plus 12 inches on each side for pipes up to 24 inches in diameter.
NOTE Unnecessarily wide trenches increase the volume of backfill and the potential for consolidation settlement. (7.4.4)
7.4.5 Trenches shall be excavated to stable, undisturbed material.
7.4.6 Where unstable trench bottom conditions are encountered, the geotechnical engineer shall evaluate the need for over-excavation and replacement with crushed stone or other suitable material.
7.4.7 Trench sidewalls shall be stable during the time workers are in the trench.
7.4.8 Every trench 5 feet or deeper shall have a protective system as required by OSHA 29 CFR 1926 Subpart P.
7.4.9 The Contractor shall not permit workers in an unprotected trench 5 feet or deeper for any reason, including hand trimming, pipe laying, or inspection.
7.5 Excavation Beneath Groundwater
7.5.1 Where excavation extends below the groundwater table, the Contractor shall manage groundwater by dewatering as described in the dewatering section of this specification.
NOTE Excavation into groundwater without effective dewatering causes piping, boiling, and bottom heave that destroys the integrity of the bearing surface and is an immediate safety hazard. (7.5.2)
7.5.3 The Contractor shall not allow workers in an excavation where active groundwater inflow is occurring and the bottom is not stable.
7.6 Stockpile Management
7.6.1 Stockpiles of excavated material shall be located at least 2 feet from the edge of any excavation for stockpiles less than 5 feet high, and farther for taller stockpiles, to prevent surcharge-induced slope failure into the excavation.
7.6.2 Stockpile heights shall not exceed the maximum for the soil type unless the geotechnical engineer approves a higher stockpile with appropriate side slopes.
7.6.3 Stockpiles shall be protected from excessive drying, wetting, or freezing that would render the material unsuitable for its intended reuse.
8 Excavation Support and Dewatering
8.1 Excavation Support — General
Sloping and benching per OSHA Appendix B
Aluminum hydraulic shoring (tabulated data)
Steel sheet piling
Soldier beams and wood lagging
Secant or tangent pile wall
Trench box / shield
Designed system — PE-stamped drawings required
8.1.1 All excavations 5 feet or deeper shall be protected by a sloping/benching system or a support system designed to prevent cave-in, as required by OSHA 29 CFR 1926 Subpart P.
8.1.2 Protective systems shall be selected from the OSHA-tabulated options (sloping per Appendix B, timber shoring per Appendix C, aluminum hydraulic shoring per Appendix D) or shall be designed by a registered professional engineer.
8.1.3 The competent person shall evaluate soil conditions and select or confirm the appropriate protective system for each excavation.
8.1.4 Selection of a protective system is the responsibility of the Contractor; the Engineer of Record's review of the excavation safety plan does not constitute approval of the protective system design.
8.1.5 Where excavation support is designed by the Contractor's engineer, the design shall account for soil type and stratification based on the project geotechnical report, groundwater level and hydrostatic pressure, surcharge loads from stockpiles, equipment, and adjacent structures, and any restrictions on ground movement that protect adjacent foundations, utilities, or improvements.
8.1.6 The Owner's Engineer of Record shall be consulted before any designed support system is installed that affects permanent structures or existing improvements.
8.2 Temporary Shoring Adjacent to Existing Structures
Engineered shoring system — PE-stamped drawings required
Underpinning of existing foundation
Not applicable — no excavation within 10 ft of existing foundations
8.2.1 When excavating adjacent to existing buildings, foundations, pavements, or utilities, the Contractor shall evaluate whether the excavation will undermine the support of adjacent improvements.
8.2.2 No excavation that removes lateral or vertical support from an existing foundation shall be performed without either underpinning the existing foundation or designing and installing a temporary support system adequate to prevent movement.
8.2.3 IBC Chapter 18 requires that excavation near any foundation not reduce vertical or lateral support without prior protection of the affected foundation.
8.2.4 The Contractor shall monitor any existing structures adjacent to deep excavations for signs of movement or distress.
8.2.5 Pre-construction condition surveys shall be performed on adjacent structures within a distance equal to the depth of excavation, and the Contractor shall maintain records sufficient to defend against claims of damage.
8.3 Dewatering
NOTE Dewatering removes groundwater from excavations to maintain dry working conditions, prevent bottom heave and piping, and allow compaction of fill to meet density requirements. (8.3.1)
Sump pumping with open ditches
Submersible pumps in gravel sumps
Wellpoints
Deep wells (submersible turbine pumps)
Eductor / vacuum wellpoints
Not required — groundwater below excavation depth
Discharge to sanitary sewer with utility owner approval
Discharge to storm system with permit and sediment settling
Discharge to vegetated buffer on site
Sediment basin before off-site discharge
8.3.2 The Contractor shall provide dewatering systems capable of maintaining the water level at least 2 feet below the working level in every excavation, unless the geotechnical report indicates that a lower drawdown is required.
8.3.3 The Contractor shall maintain dewatering continuously during all excavation and fill operations until the fill or structure has progressed to a height where groundwater no longer affects compaction or bearing capacity.
8.3.4 Dewatering shall not be discontinued abruptly.
8.3.5 If dewatering equipment fails, the Contractor shall immediately notify the Engineer of Record and take emergency measures to prevent flooding of the excavation.
8.3.6 Groundwater shall not be discharged in a manner that causes erosion, flooding, or contamination of adjacent properties; all dewatering discharge shall comply with applicable NPDES permit conditions and local stormwater regulations.
8.3.7 Where dewatering causes settlement of adjacent soils or structures, the Contractor shall stop dewatering, notify the Owner and Engineer of Record, and not resume until a revised dewatering plan is approved.
8.3.8 Fine-grained soils are susceptible to consolidation settlement when groundwater is permanently lowered; the effect on adjacent improvements shall be evaluated by the geotechnical engineer before dewatering begins in such soils.
9 Fill and Backfill Materials
9.1 Material Categories
9.1.1 Fill materials shall be free of organic material, frozen lumps, ice, snow, debris, and other deleterious matter.
9.1.2 All fill material sources — whether excavated from the site or imported — shall be evaluated and approved by the geotechnical engineer before placement.
9.1.3 The Contractor shall not change material sources without re-evaluation and approval.
9.1.4 Structural Fill
NOTE Structural fill is used beneath foundations, floor slabs, pavements, and other load-bearing applications where settlement or inadequate bearing capacity would cause structural damage. (9.1.4.1)
☐ GW — Well-graded gravel
☐ GP — Poorly graded gravel
☐ GM — Silty gravel
☐ GC — Clayey gravel
☐ SW — Well-graded sand
☐ SP — Poorly graded sand
☑ SM — Silty sand
☐ SC — Clayey sand
☐ CL — Low-plasticity clay (with geotechnical engineer approval)
● 3 in. (lifts up to 8 in.)
○ 6 in. (lifts up to 12 in.)
○ Per geotechnical engineer
9.1.4.2 Structural fill shall be granular or low-plasticity cohesive material with USCS classification GW, GP, GM, GC, SW, SP, SM, or SC unless the geotechnical report specifies otherwise.
9.1.4.3 Structural fill maximum particle size shall be 3 inches for lifts up to 8 inches and 6 inches for lifts up to 12 inches, and no particle shall exceed two-thirds of the compacted lift thickness.
9.1.4.4 Structural fill liquid limit shall not be greater than 40.
9.1.4.5 Structural fill plasticity index shall not be greater than 15.
9.1.4.6 Structural fill shall be free of organics and deleterious material.
9.1.4.7 Where the geotechnical report indicates that on-site soils are not suitable as structural fill, or where the volume of suitable material is insufficient, the Contractor shall import approved granular fill.
9.1.4.8 Imported structural fill shall be certified by a qualified laboratory prior to delivery, and certification shall include gradation analysis per ASTM C136/C136M and ASTM D7928, Atterberg limits per ASTM D4318, and Proctor test per ASTM D1557, performed on a sample representative of the import source.
9.1.5 Select Granular Fill
NOTE Select granular fill is a high-quality, free-draining material used for pipe bedding, drainage layers under slabs, and applications where low compressibility and positive drainage are required. (9.1.5.1)
● 5 percent
○ 8 percent
○ 12 percent (engineering judgment required)
9.1.5.2 Select granular fill shall have USCS classification GW, GP, SW, or SP.
9.1.5.3 Select granular fill maximum particle size shall be 1.5 inches unless otherwise specified.
9.1.5.4 Select granular fill shall be non-plastic (liquid limit).
9.1.5.5 Select granular fill fines content (material passing the No. 200 sieve) shall not be greater than 5 percent.
9.1.6 Controlled Low-Strength Material (CLSM)
9.1.6.1 Controlled Low-Strength Material (CLSM), also known as flowable fill, is a self-compacting cementitious fill that may be used as an alternative to compacted fill in confined spaces, around complex structures, or where compaction is not feasible.
○ Not permitted — all backfill shall be compacted granular or cohesive fill
● Permitted in designated locations only — Engineer of Record approval required
○ Permitted at Contractor's option in inaccessible locations
9.1.6.2 CLSM shall be used only where approved by the Engineer of Record.
9.1.6.3 CLSM mix design shall achieve a 28-day compressive strength of 30 to 200 psi where future excavation may be required, or up to 1,200 psi where re-excavation is not anticipated.
9.1.7 General Site Fill
NOTE General site fill is used in areas remote from structures where settlement over time is acceptable, such as landscaped areas and non-traffic areas beyond the building footprint. (9.1.7.1)
9.1.7.2 General site fill may include cohesive soils with higher plasticity than structural fill, provided the material is free of organics and debris.
9.1.7.3 General site fill shall have USCS classification GW, GP, GM, GC, SW, SP, SM, SC, ML, CL, or ML-CL.
9.1.7.4 General site fill maximum particle size shall be 3 inches.
9.1.7.5 General site fill plasticity index shall not be greater than 30.
9.1.7.6 General site fill shall be free of organics and deleterious material.
9.1.7.7 General site fill shall not be used within 10 feet of building foundations or within any utility trench or pavement subgrade zone unless specifically approved by the geotechnical engineer.
9.1.8 Unsuitable Material — Use Prohibited
9.1.8.1 The following materials shall not be used as fill in any application: organic soils, topsoil, peat, or muck; frozen material; high-plasticity material; debris-laden or contaminated material; and combustible material.
● Remove from site and dispose legally
○ Stockpile on site at designated location — Owner approval required
9.1.8.2 Organic soils, topsoil, peat, or muck (any material with organic content greater than 3 percent by mass) shall not be used as fill in any application.
9.1.8.3 Frozen material shall not be used as fill in any application.
9.1.8.4 Material with liquid limit greater than 50 or plasticity index greater than 25 shall not be used as fill in any application, unless specifically approved by the geotechnical engineer for a stated application.
9.1.8.5 Material containing construction debris, chemical contamination, or deleterious substances shall not be used as fill in any application.
9.1.8.6 Trash, wood, and combustible material shall not be used as fill in any application.
9.2 Fill Material Testing Before Placement
9.2.1 The Contractor shall submit laboratory test results for each fill source — both on-site stockpiles and import sources — before that material is placed, including USCS classification, gradation, Atterberg limits, and Proctor compaction curve.
9.2.2 If the source material changes in character during production (e.g., a stockpile contains zones of different material), additional testing shall be performed.
9.2.3 The geotechnical engineer shall be notified of any material change that may affect suitability.
10 Compaction
10.1 General Compaction Requirements
NOTE Compaction is the densification of soil by mechanical energy that reduces void space, increases dry density, and reduces future settlement potential. (10.1.1)
NOTE The energy is delivered by compaction equipment — vibratory rollers, tamping foot rollers, plate compactors, and pneumatic rollers — and the effectiveness depends on equipment type, lift thickness, number of passes, and most critically, on the moisture content of the soil relative to its optimum. (10.1.2)
6 in.
8 in.
12 in. (where vibratory roller equipment is used and geotechnical engineer verifies)
10.1.3 Compaction shall be performed in uniform horizontal lifts of the thickness specified herein, using equipment appropriate for the soil type and application.
10.1.4 No fill shall be placed on frozen subgrade, and no compaction shall be performed on material that is frozen.
10.1.5 Lift thickness shall not exceed the capability of the compaction equipment to achieve uniform density through the full lift depth.
NOTE A common compaction error is placing lifts that are thicker than the equipment can penetrate, producing a dense top crust that passes density testing while the lower portion remains loose. (10.1.6)
10.1.7 The geotechnical engineer may require proof of uniform compaction by performing density tests at mid-lift depth where there is reason to suspect layering.
10.2 Moisture Conditioning
NOTE Soil compaction achieves its maximum density at optimum moisture content, as determined by the Proctor test. (10.2.1)
Within -2% to +2% of optimum (cohesive fine-grained soils)
Within -3% to +1% of optimum (granular soils — prevent collapse on wetting)
Within -2% to +3% of optimum (less critical fill areas)
Per geotechnical engineer — site-specific recommendation
NOTE Soil that is too dry will not compact fully regardless of roller passes, and soil that is too wet will pump under roller traffic and cannot achieve the required density without drying; both conditions are common causes of compaction failures. (10.2.2)
10.2.3 The Contractor shall measure soil moisture before compaction using a nuclear gauge per ASTM D6938 or by laboratory determination per ASTM D2216.
10.2.4 If fill is too dry, it shall be wetted uniformly using water trucks or sprinklers and allowed to condition before compaction begins.
NOTE Surface wetting without adequate mixing does not bring the full lift to optimum moisture. (10.2.5)
10.2.6 If fill is too wet, it shall be aerated by discing, blading, or windrowing until moisture falls within the acceptable range.
10.2.7 The Contractor shall not attempt to compact overly wet material in the expectation that density testing will pass.
10.2.8 Highly plastic clays are particularly difficult to moisture-condition because they absorb and release water slowly, and such soils may require extended conditioning periods or should be replaced with more workable material.
10.3 Compaction Requirements by Application
10.3.1 Structural Fill Under Foundations and Grade Beams
92100
959798100
Default: 95 percent of Modified Proctor (ASTM D1557) maximum dry density
10.3.1.1 Structural fill placed beneath footings, grade beams, mat foundations, and foundation walls shall be compacted to a minimum of 95 percent of Modified Proctor maximum dry density (ASTM D1557) unless the geotechnical report specifies a higher value.
10.3.1.2 The geotechnical engineer shall determine the required bearing capacity from the project report and shall direct the compaction criterion accordingly.
10.3.1.3 For highly loaded foundations or expansive soil conditions, compaction to 98 or 100 percent of Modified Proctor may be required.
10.3.2 Structural Fill Under Floor Slabs and Pavements
90100
929598
Default: 95 percent of Modified Proctor (ASTM D1557) maximum dry density
10.3.2.1 Fill beneath floor slabs, concrete pavements, and asphalt pavements shall be compacted to a minimum of 95 percent of Modified Proctor maximum dry density unless the structural drawings specify a higher value.
10.3.2.2 The top 6 inches of subgrade immediately beneath the slab or base course shall be compacted to not less than 95 percent of Modified Proctor.
10.3.3 Trench Backfill
90100
90929598
Default: 95 percent of Modified Proctor (ASTM D1557) maximum dry density
8598
85909295
Default: 90 percent of Modified Proctor (ASTM D1557) maximum dry density
10.3.3.2 Trench backfill in unpaved areas remote from structures shall be compacted to a minimum of 90 percent.
10.3.3.3 Initial backfill directly over pipe shall be hand-tamped or lightly compacted with small equipment to avoid pipe damage, and after the initial backfill covers the pipe crown by 12 inches, heavier equipment may be used.
10.3.4 General Site Grading
8595
85909295
Default: 90 percent of Standard Proctor (ASTM D698) maximum dry density
10.3.4.1 Fill in landscaped areas, turf areas, and other non-traffic, non-structural areas shall be compacted to a minimum of 90 percent of Standard Proctor (ASTM D698) maximum dry density.
NOTE This value provides adequate stability for surface drainage and vehicle access without over-compacting areas that will be planted. (10.3.4.2)
10.4 Compaction Equipment
10.4.1 Compaction equipment shall be selected based on soil type and application.
NOTE Vibratory smooth-drum rollers are effective for granular materials. (10.4.2)
NOTE Plate compactors and jumping jack tampers are used in confined areas and around utilities where large rollers cannot operate. (10.4.4)
☑ Vibratory smooth-drum roller
☐ Tamping foot (sheepsfoot) roller
☐ Pneumatic-tired roller
☐ Plate compactor
☐ Jumping jack (vibratory rammer)
☐ Hand tamper — adjacent to structures only
10.4.5 The compaction equipment shall be of adequate size to achieve the required density in the specified lift thickness.
NOTE Light equipment used on heavy lifts will not achieve required compaction regardless of passes. (10.4.6)
10.5 Compaction Adjacent to Structures
○ 3 ft
● 5 ft
○ 8 ft (near sensitive structures)
10.5.1 Compaction equipment shall not operate within 5 feet of any foundation wall, retaining wall, buried structure, or buried utility without the approval of the Engineer of Record.
NOTE Heavy vibratory equipment transmits dynamic loads that can crack concrete, displace reinforcement, or damage flexible pipe. (10.5.2)
10.5.3 In the zone within 5 feet of any structure, compaction shall be performed with hand-operated vibratory plate compactors or jumping jack tampers in lifts not exceeding 6 inches.
10.5.4 The Contractor shall verify that the approved compaction equipment achieves the required density in confined zones by performing test strips before committing to full production.
10.6 Verification of Compaction — Failing Tests
10.6.1 When a field density test fails to achieve the required percent compaction, the Contractor shall immediately cease filling the affected area, scarify and rework the failing lift, adjust moisture content if needed, re-compact, and request re-testing at the same location before proceeding.
NOTE A single passing test after a failure does not eliminate the need to understand why the failure occurred. (10.6.2)
10.6.3 The geotechnical engineer shall evaluate patterns of repeated failure, which may indicate that the material is unsuitable, the moisture is persistently out of range, or the equipment is inadequate, and shall direct corrective action.
10.6.4 The Contractor shall not hide failed test results or attempt to proceed past a failing test based on verbal assurances.
10.6.5 All test results, including failures, shall be documented, and the corrective action shall be recorded before the next test in the same area.
11 Subgrade Preparation
11.1 Foundation Bearing Subgrade
○ Geotechnical engineer present for all foundation excavation bottoms
● Geotechnical engineer called for observation — minimum 24-hour advance notice
11.1.1 The bearing surface for every spread footing, strip footing, mat foundation, and grade beam shall be observed by the geotechnical engineer of record before any concrete, lean fill, or other material is placed.
11.1.2 The observation shall confirm that the bearing elevation matches the design, that the material is the bearing stratum identified in the geotechnical report, and that there are no soft spots, disturbed zones, or groundwater that would compromise bearing capacity.
11.1.3 Loose material, disturbed soil, and standing water shall be removed before observation.
11.1.4 If the bearing stratum is exposed more than 2 hours in advance of concrete placement, the top 2 to 3 inches shall be re-trimmed immediately before placement to remove desiccated crust in fine-grained soils or disturbed material in granular soils.
11.1.5 In freezing weather, bearing surfaces shall be protected from frost and shall be confirmed unfrozen by the geotechnical engineer before concrete is placed.
11.2 Proof Rolling
NOTE Proof rolling consists of driving a fully loaded, rubber-tired vehicle over the prepared subgrade surface to identify soft, pumping, or yielding areas that indicate inadequate bearing or insufficient compaction. (11.2.1)
● Required — all areas under structural fill, slabs, and pavements
○ Required — areas as directed by geotechnical engineer
○ Not required on this project
Fully loaded tandem-axle dump truck (minimum 20-ton loaded weight)
Fully loaded tri-axle dump truck (minimum 25-ton loaded weight)
As directed by geotechnical engineer
11.2.2 Proof rolling shall be performed on all areas to receive structural fill under foundations or slabs, on all subgrades to receive base course under pavements, and at any location where the geotechnical engineer suspects inconsistent subgrade conditions.
11.2.3 The geotechnical engineer shall observe all proof rolling.
11.2.4 Areas that exhibit more than 0.5 inch of deformation, rut, or pumping shall be undercut to competent material and replaced with approved structural fill or otherwise stabilized as directed by the geotechnical engineer.
11.2.5 The Contractor shall not proceed with fill placement or base course until all failing areas have been remediated and re-proof-rolled.
11.3 Subgrade Stabilization
11.3.1 Where the subgrade is soft, wet, or otherwise unable to support compaction equipment or proof-rolling, the geotechnical engineer shall evaluate stabilization options, which include mechanical stabilization, geosynthetic stabilization, chemical treatment, or undercutting and replacement.
Crushed stone working layer — per geotechnical engineer
Geotextile separator with granular fill — per geotechnical engineer
Lime treatment — per geotechnical engineer (mix design required)
Cement treatment — per geotechnical engineer (mix design required)
Undercut and replace with structural fill — per geotechnical engineer
Not required — subgrade confirmed competent by geotechnical engineer
11.3.2 Mechanical stabilization may be provided by placing and compacting a layer of clean crushed stone (12 to 24 inches) that bridges the soft zone.
11.3.3 Geosynthetic stabilization may be provided using a geotextile separator over the soft zone, followed by granular fill.
11.3.4 Lime or cement treatment of cohesive fine-grained soils may be used to improve workability and bearing capacity.
11.3.5 Undercutting and replacement with approved granular fill may be used to stabilize a soft, wet, or unstable subgrade.
11.3.6 Lime and cement treatment requires a mix design developed by a qualified laboratory, field application with calibrated equipment, and curing before the treated layer is loaded.
11.3.7 Treated layers shall be re-tested before being loaded to confirm achievement of the target unconfined compressive strength.
11.4 Slab-on-Grade Subgrade — Granular Capillary Break
● Provided — 4 in. clean crushed stone per drawings
○ Provided — 6 in. clean crushed stone per drawings
○ Not required — vapor retarder placed directly on compacted subgrade
11.4.1 Where slabs on grade are designed with a capillary break layer, the layer shall consist of clean crushed stone with less than 5 percent fines (USCS SP or GP), placed and compacted in a single layer of the thickness shown on the drawings.
11.4.2 The capillary break layer shall be placed after the subgrade has been proof-rolled and accepted by the geotechnical engineer.
11.4.3 The capillary break layer shall be compacted with a vibratory plate compactor to a stable surface and shall not be over-compacted to the point of crushing aggregate.
11.4.4 The capillary break layer shall not be contaminated with fines from traffic before the vapor retarder and concrete are placed.
12 Erosion and Sediment Control
12.1 Regulatory Framework and SWPPP
NOTE Construction activities that disturb 1 acre or more of land — or less if part of a common plan of development that totals 1 acre or more — require coverage under the EPA Construction General Permit (CGP) or the applicable state NPDES stormwater permit before grading begins. (12.1.1)
● Yes — land disturbance 1 acre or greater; SWPPP required before grading
○ Yes — part of common plan of development totaling 1 acre or greater
○ No — land disturbance less than 1 acre; verify with local authority
12.1.2 The Contractor shall obtain all required stormwater permits, prepare a Stormwater Pollution Prevention Plan (SWPPP) in accordance with the permit requirements, and maintain the SWPPP on site at all times for inspection.
12.1.3 The SWPPP shall describe every Best Management Practice (BMP) to be used, the location of each BMP shown on a site map, the sequence of installation relative to grading operations, the maintenance and inspection protocol, and the basis for determining when the permit can be terminated at project completion.
12.1.4 The SWPPP shall be updated when conditions change, when BMPs prove ineffective, or when new areas of disturbance are added.
12.2 Sediment Control at Site Perimeter
12.2.1 The perimeter of the site shall be protected by sediment controls installed before grading begins, to intercept sediment-laden runoff before it leaves the site.
Silt fence (slopes not exceeding 2:1, drainage area not exceeding 0.25 acre per 100 ft)
Fiber wattle / compost sock
Rock check dams (swales and channels)
Sediment basin (drainage areas exceeding 5 acres)
Per drawings — SWPPP site plan
12.2.2 Silt fence shall be installed by slicing the fabric into the soil using a mechanical device or by digging a 6-inch trench, inserting the fabric, and backfilling.
NOTE Fabric simply staked to the surface without embedment will fail in the first rain event. (12.2.3)
12.2.4 Silt fence shall be inspected after every rain event and repaired or replaced when sediment accumulation reaches one-third of the exposed fabric height.
12.3 Stabilized Construction Entrance
12.3.1 A stabilized construction entrance shall be provided at every point where construction vehicles enter or exit the site onto a public road, to remove mud and sediment from tires before vehicles reach the pavement.
● 1.5 in. to 3 in. crushed stone
○ 2 in. to 4 in. crushed stone
○ Recycled concrete aggregate
12.3.2 The stabilized entrance shall extend from the public road into the site at least 50 feet, or the full length of the ingress/egress zone if shorter.
12.3.3 Where vehicles track mud onto public roads despite the stabilized entrance, the Contractor shall arrange for street sweeping at a frequency that prevents sediment buildup.
12.4 Temporary Slope Protection
NOTE Temporary seeding with fast-germinating annual grasses provides cost-effective erosion protection for exposed slopes during construction. (12.4.1)
Temporary seeding — slopes 3:1 or flatter
Erosion control blanket (straw, wood fiber, or coconut) — slopes steeper than 3:1
Hydraulic mulch / hydroseed
Compost blanket
Combination per SWPPP
12.4.2 Disturbed slopes shall be protected from erosion by temporary seeding, erosion control blankets, compost applications, or other approved methods when the slope will be exposed for more than 7 days on slopes steeper than 3:1 or more than 14 days on slopes 3:1 or flatter.
12.5 Storm Inlet Protection
12.5.1 All storm drain inlets within or immediately downslope of the construction area shall be protected with inlet protection devices to prevent sediment from entering the storm drainage system.
Silt fence with stakes around inlet
Prefabricated inlet protection device
Rock filter dike around inlet
Drop inlet sediment trap
12.5.2 Inlet protection shall be installed before grading begins in the contributing drainage area.
12.5.3 Inlet protection devices shall be inspected after every rain event and cleaned when sediment accumulates to one-half the device capacity.
12.5.4 Clogged inlet protection that blocks drainage and causes ponding presents a flooding risk and shall be cleaned immediately.
12.6 Erosion Control Maintenance and Inspection
● Weekly and within 24 hours after rain events of 0.5 inch or greater
○ Every 7 days (regardless of rain events)
○ Per permit requirements — check applicable CGP conditions
12.6.1 All erosion and sediment control BMPs shall be inspected by the Contractor's designated responsible party at least weekly and within 24 hours after any rain event of 0.5 inch or greater.
12.6.2 Inspection records shall document the condition of each BMP, any deficiencies noted, and corrective actions taken.
12.6.3 Corrective actions shall be completed within 24 hours of inspection unless weather prevents it, in which case they shall be completed as soon as practicable.
12.6.4 At project completion, all temporary erosion and sediment control BMPs shall be removed and disturbed areas stabilized with permanent vegetation or hardscape.
12.6.5 Temporary BMPs shall not be removed until the areas they protect have achieved permanent stabilization.
12.6.6 Silt fence fabric and other synthetic materials shall be collected and disposed of properly and shall not be buried in place.
13 Field Testing and Quality Control
13.1 Compaction Testing Program
13.1.1 Field compaction testing shall be performed by the Owner-retained special inspection or geotechnical firm.
● Yes — testing agency retained by Owner, independent of Contractor
○ No — project below threshold requiring special inspection (verify with AHJ)
NOTE Testing is Owner-retained because the testing entity must be independent of the Contractor — Contractor-retained testing for compaction acceptance is not acceptable for structural applications. (13.1.2)
13.1.3 The Contractor shall cooperate fully with the testing agency, provide access to all fill areas, and provide information about lift locations, material types, and moisture conditioning operations.
13.1.4 The testing agency shall use nuclear density gauge testing per ASTM D6938 as the primary production method, with sand cone tests per ASTM D1556/D1556M for verification or calibration.
13.1.5 The nuclear gauge shall be standardized at the beginning and end of each shift.
13.1.6 Gauge count standard results shall be recorded and compared to the reference standards.
13.1.7 If count ratios fall outside acceptable limits, the gauge shall be recalibrated before testing continues.
13.2 Testing Frequency Requirements
13.2.1 Minimum testing frequencies, in the absence of project-specific geotechnical recommendations, shall be one test per 2,500 sf of fill surface per lift under foundations and grade beams; one test per 2,500 sf of fill surface per lift under floor slabs and pavements; one test per 100 lf of trench per lift for utility trench backfill within structures or pavement; one test per 250 lf of trench per lift for utility trench backfill in open areas; one test per 5,000 sf of fill surface per lift for general site grading; and additional tests wherever the geotechnical engineer identifies variable conditions or failing results.
1 test per 2,500 sf
1 test per 1,500 sf (higher-risk or variable conditions)
1 test per 500 sf (special inspection continuous observation)
Per geotechnical engineer
13.2.2 Testing shall be performed at one test per 2,500 sf of fill surface per lift under foundations and grade beams.
13.2.3 Testing shall be performed at one test per 2,500 sf of fill surface per lift under floor slabs and pavements.
13.2.4 Testing shall be performed at one test per 100 lf of trench per lift for utility trench backfill within structures or pavement.
13.2.5 Testing shall be performed at one test per 250 lf of trench per lift for utility trench backfill in open areas.
13.2.6 Testing shall be performed at one test per 5,000 sf of fill surface per lift for general site grading.
13.2.7 Additional tests shall be performed wherever the geotechnical engineer identifies variable conditions or failing results.
13.3 Proctor Reference Curves
○ One per on-site material type placed as structural fill
○ One per import source
● Both — on-site and import sources
13.3.1 For each distinct fill material on the project, a Proctor reference curve (maximum dry density vs. moisture content) shall be established by laboratory testing before that material is placed in the field.
NOTE Field density results are meaningless without an accurate reference Proctor. (13.3.2)
13.3.3 If visual observation by the geotechnical engineer suggests that the material being placed has changed from the material on which the reference Proctor was performed, the geotechnical engineer shall direct verification testing on the new material before compaction acceptance continues.
13.4 Foundation Bearing Pressure Verification
13.4.1 Where the structural design is based on a minimum allowable bearing pressure, the geotechnical engineer of record shall confirm that the bearing material at the foundation bearing elevation is consistent with the material on which the design bearing pressure is based.
13.4.2 Consistency is established by visual observation, standard penetration test blow counts from boring logs, hand penetrometer readings, or dynamic cone penetrometer testing in the bearing surface, as appropriate to the material type.
13.4.3 The geotechnical engineer's written observation report for each foundation bearing elevation shall be provided to the Owner and Engineer of Record and retained in the project file.
13.5 Gradation and Plasticity Testing of Fill Materials
13.5.1 In addition to Proctor and density testing, the geotechnical engineer may direct gradation and Atterberg limits tests on fill materials at any time during construction to confirm continued conformance to the approved material description.
13.5.2 Gradation and plasticity testing shall be performed when material appearance changes, when a new stockpile or import delivery is initiated, or when compaction testing shows unexplained variability that may indicate a material change.
13.5.3 Gradation and plasticity test frequency shall be as directed by the geotechnical engineer.
13.6 Documentation and Reporting
● Within 24 hours of test
○ Same day (digital submittal)
○ Weekly batch — not acceptable for structural applications
13.6.1 All field testing data shall be recorded on forms that include project name, test date, test location (plan coordinates or station and offset, plus depth or lift number), material description, moisture content, wet density, dry density, percent compaction relative to the applicable Proctor, and pass/fail determination.
13.6.2 The testing agency shall provide results to the Owner and Contractor within 24 hours of testing.
13.6.3 Failing tests shall be flagged immediately and shall not be buried in a batch report delivered days later.
NOTE The Contractor must have immediate notice to stop work and address the failure. (13.6.4)
14 Warranty
14.1 The Contractor shall warrant earthwork operations for the project warranty period beginning at substantial completion.
1 year from substantial completion
2 years from substantial completion
○ Yes — install monuments per geotechnical engineer direction
● No — not required on this project
14.2 The Contractor shall warrant earthwork operations, including achievement of specified grades, compaction of all fill and backfill, and the performance of erosion and sediment control measures, for the project warranty period beginning at substantial completion.
14.3 Warranty obligations include correction of settlement, heaving, erosion, or other defects attributable to non-conforming earthwork operations.
14.4 The warranty does not relieve the Contractor of liability for concealed non-conforming work discovered after the warranty period expires, nor does it limit the Owner's remedies for latent defects.
14.5 Settlement or structural distress discovered after the warranty period that is attributable to inadequate compaction or non-conforming fill materials shall be evaluated by the geotechnical engineer and may constitute a latent defect extending beyond the warranty term.
14.6 Settlement monitoring pins or monuments shall be installed where directed by the geotechnical engineer to provide objective data on fill performance during the warranty period.
14.7 Readings shall be taken at the intervals specified by the geotechnical engineer and reported to the Owner.
14.8 Accelerated settlement that exceeds the predicted range shall be reported immediately.