Test pits are holes dug prior to construction to help ensure the ground conditions are suitable for building projects. These test pits average a depth of 3-15 feet deep, and allow geotechnical engineers the opportunity to assess soil composition before officially breaking ground. Using a test pit is a great way to avoid issues and save costs — learn how to dig test pits and more with Central Geotech.
What are the Benefits of a Test Pit?
Digging a test pit on your land helps you get a sense of whether or not the development location can support upcoming construction. A test pit can uncover:
- Soil contamination
- Buried structures
- Unsuitable soil conditions
- Water table location
- Side wall stability
- Groundwater seepage
- Potential challenges in project structure
The biggest benefit of a test pit is cost savings. Excavators are far less expensive than drilling work, and finding any of the above issues when you’re well into a project can cause major time delays and extra expense, pushing out deadlines while costs soar.
How to Dig Test Pits
Multiple test pits can be dug in less than a day, often with a limited crew, which is why Central Geotechnical Services uses this method as a best practice where feasible. Follow our tips on how to dig test pits—but please—before you dig, have us out to the site so we can see the actions happen. There’s a lot of translation in the soil as the work is being done—not just the result of the open hole in the ground!
- Choose the right location: Aim to dig several trial pits spread out across your property to get a good cross section of conditions.
- Utility Locates: Allow Central Geotech to arrange and coordinate private and public utility locates to help minimize risk of damaging underground lines.
- Dig beyond foundation depth as necessary: A test pit should be at least a few feet deeper than the upcoming construction’s foundation. Many test pits average at a twelve-foot depth, as equipment gets much larger (and more expensive) if deeper test pits are needed.
- Test soil: NEVER enter the test pit without shoring in place. Use the dug soil to test its makeup and visually investigate contamination concerns.
- Refill the pit: Once samples are gathered, backfill the area and document the conditions.