What is a Test Pit?

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.

Request Test Pits for Your Next Project If Feasible

Central Geotechnical Services uses test pits for our site investigations to save money and worry down the road. Contact us with any questions and find out how we can help.