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Unsuitable Soil to Solid Ground – What is Dynamic Compaction?

Posted in: News on March 21, 2018 | By Sara Gambone

Optimizing Land

Land has always been an important part of Lancaster County’s history. From the early days, settlers were drawn to the area for its fertile soil, and its rural beauty has been a point of pride for locals ever since – but the recent wave of development has some people concerned that the sprawling acres of farmland are threatened. However, not all land in Lancaster is beautiful. In order to prevent overdevelopment, we have to make smarter use of less conventional spaces, even if that isn’t the easiest option. Reclaiming brownfield sites and working on sites with unsuitable soil certainly has its challenges, but these can be overcome with the use of innovative construction solutions.

As good, developable land gets scarcer and scarcer, in Lancaster and across the Mid-Atlantic and Northeast, having a project team behind you that can handle the challenges of building on unsuitable soil is essential. It takes a team that is creative and innovative – one that knows the benefits and drawbacks of each method, so they can understand which will work best for your project.

unsuitable soil

Unsuitable Soil at CityGate Corporate Center

Wohlsen’s ability to do this was recently demonstrated on the CityGate Corporate Center for Oak Tree Development. The CityGate project was slated to be built on a parcel of land bordering the federally protected Dillerville wetlands. Though the surrounding land would not interfere with this important ecological feature, it still had loose, unsuitable soil. The site would not be able to support the corporate complex. However, Wohlsen Construction worked in tandem with the project team to develop a practical, cost-effective solution to continue the project. As a result, the team established a plan that would, quite literally, let the project stand on solid ground!

What is Dynamic Compaction?

unsuitable soil

By employing a method called dynamic compaction, we increased the density of the soil, turning the loose, unsuitable soil into a site that can adequately support the structure.

The process involves repeatedly raising and dropping a heavy weight from varying heights to impact the ground multiple times. This impact releases energy which densifies the soil deposits below. The higher the crane and the heavier the weight that is dropped, the deeper the improvements and sturdier the soil.

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Dynamic compaction in progress on the CityGate site.

The drops are generally applied in phases on a grid pattern over the entire area, sometimes requiring several passes. Following each pass, the craters created are leveled or filled with granular fill material before the next pass.

Working with the client, the method was chosen over other methods of soil amendment that require piles or soil replacement. Dynamic compaction would give adequate support at a much lower cost. Additionally, the less-invasive method would have a much smaller impact on the schedule prior to construction, allowing the team to get a running start on the project.

With less and less developable land available, smart methods of improving unsuitable soil will be required. Wohlsen will work with you to determine which method will be best, laying the foundations for a successful project!

Are you thinking about starting a project on a challenging site or on unsuitable soil? Let’s talk about how we can help make the process a little easier!


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