Homeâ€ºServicesâ€ºCompaction Testing

Geotechnical

Compaction Testing

Field density testing during grading and earthwork to verify that fill soils meet the compaction requirements specified in your geotechnical report and grading permit.

What Is Compaction Testing?

Compaction testing — also called field density testing — measures the in-place density and moisture content of fill soils during grading. The results are compared against the laboratory maximum dry density (from a Proctor test) to confirm that the fill has been compacted to the minimum percentage specified in your soils report, typically 90% relative compaction for structural areas and 85% for non-structural fill.

Compaction testing is a code requirement for any project that involves placing engineered fill. The grading contractor cannot proceed with the next lift of fill or with foundation construction until each lift is tested and approved. Moment Engineering provides same-day results and maintains a field technician schedule that supports the fast-paced timelines of residential and commercial grading in Southern California.

Same Day

Test results delivered — typically within hours of testing

90%

Minimum relative compaction required for structural fill (typical)

6–8 in

Maximum compacted lift thickness per standard grading specifications

Need Compaction Testing? Get a fixed-fee proposal — typically within 24 hours.

Request a Proposal ✆ (619) 374-8677

Typical Investment

$500 – $2,000per visit

Per-visit pricing. Total depends on project duration and number of inspections required.

Fees vary by site conditions, scope, and jurisdiction. Request a proposal for a fixed-fee quote tailored to your project.

Scope of Work

What's Included

☢️

Nuclear Gauge Density Testing

In-place density and moisture measurements using a calibrated Troxler nuclear density gauge per ASTM D6938. Tests are performed at representative locations within each lift of fill.

🧪

Laboratory Maximum Density (Proctor)

ASTM D1557 (Modified Proctor) laboratory compaction tests — the standard for structural fill in Southern California — to establish the reference maximum dry density and optimum moisture content for each soil type. ASTM D698 (Standard Proctor) is used when specified for non-structural or lightweight fill applications.

📋

Daily Field Reports

Each site visit produces a field density test report showing test location, depth, wet density, dry density, moisture content, relative compaction, and pass/fail status — emailed the same day.

📊

Final Compaction Report

A summary letter signed by the geotechnical engineer of record confirming that all fill was placed and compacted in accordance with the project specifications and approved grading plans.

👷

Grading Observation

Visual observation of site preparation, bottom and keyway excavations, fill placement, moisture conditioning, and compaction equipment performance during each site visit.

🗺️

Test Location Mapping

Test locations are recorded and mapped relative to the grading plan so that the record accurately reflects where testing was performed across the site.

When You Need Compaction Testing

Any project that places engineered fill requires compaction testing by a licensed geotechnical engineer or their representative. Common scenarios include:

Grading Permits

All grading permits in San Diego, Orange County, and LA County require compaction testing during fill placement. The grading inspector will ask for compaction reports before approving work.

Foundation Subgrade

Before pouring footings, the building inspector or soils engineer must verify that the bearing soils or compacted fill beneath the foundation meet the geotechnical report specifications.

Retaining Wall Backfill

Backfill behind retaining walls must be compacted to specification to develop the design lateral earth pressures and prevent settlement.

Utility Trench Backfill

Sewer, water, and storm drain trench backfill must be compacted in lifts to prevent settlement of pavements and flatwork above.

Pavement Subgrade

Subgrade preparation for driveways, parking lots, and roadways requires compaction testing to support the pavement structural section.

Pool & Flatwork Fill

Compacted fill beneath pool shells, patios, walkways, and other flatwork must be tested to prevent differential settlement and cracking.

Our Process

From First Call to Final Certification

Scheduling

Your grading contractor calls or texts to request testing — typically 24 hours in advance. We maintain flexible scheduling to accommodate the pace of active grading operations.

Field Testing

Our technician arrives on-site, verifies the lift thickness and moisture condition, and performs nuclear gauge density tests at representative locations. We test each lift before the contractor places the next one.

Same-Day Results

Field density test reports are emailed to the contractor, owner, and project engineer the same day. Failing tests include recommendations for reworking and retesting.

Final Report & Sign-Off

At the completion of grading, we issue a final compaction report summarizing all testing, confirming compliance, and providing the documentation needed for grading permit final inspection.

Want to learn more about what a compaction testing involves?

Read: What Is a Compaction Testing? →

Related Services

Often Paired With Compaction Testing

📄

Soils Reports

The soils report establishes the compaction specifications that field testing verifies — they go hand-in-hand on every grading project.

Learn More →

📋

Grading Plans

Grading plans define the earthwork geometry that compaction testing supports during construction.

Learn More →

🕳️

Drilling & Exploration

When unexpected soil conditions are encountered during grading, additional exploration may be needed to update recommendations.

Learn More →

Common Questions

Compaction Testing FAQs

As a general industry reference, individual site visits in Southern California typically run $350–$650 per trip; project retainers for larger grading scopes generally range $2,500–$8,000+. Fees vary based on the number of tests, travel distance, and scheduling. These are general reference figures — your actual fee will be detailed in your proposal, which we provide after a brief project review. Contact us for a same-day quote.

The general rule is one test per every 500 cubic yards of fill placed, or one test per lift per building pad area — whichever is more. For small residential sites, this usually means one visit per day of active fill placement. Your soils report and grading permit conditions will specify the minimum frequency.

The contractor reworks the failing area — typically by scarifying, adjusting moisture (adding water or aerating), and recompacting with additional passes. We return to retest. Failing results are documented in the daily report with the corrective action taken.

Not necessarily, but it's strongly recommended. The engineer of record for the soils report is already familiar with the site conditions and specifications. Using the same firm simplifies communication and ensures consistency between the geotechnical recommendations and field verification.

A Proctor test is a laboratory procedure that determines the maximum dry density and optimum moisture content of a soil — it establishes the target. A field density test (nuclear gauge) measures the in-place density during construction and compares it to the Proctor result to calculate relative compaction (percent of maximum).

Generally no. Fill placement and compaction should not occur when soils are too wet to compact properly. If it rains during grading, the contractor must allow the fill surface to dry back to near optimum moisture before resuming. We will not certify fill placed under conditions that prevent achieving specification.

Need Compaction Testing?

Need testing scheduled this week? Call or send us your project address and we'll get a technician on site — same-day and next-day availability across SoCal.

Request a Proposal ✆ (619) 374-8677