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Grayson BMW

Knoxville, Tennessee

Stormwater Retention


Grayson BMW


Michael Brady Inc.


Superior Drainage (distributor)


August 2016

The construction of overflow parking for the Grayson BMW facility initiated the need for additional stormwater management on the site.

Local regulations required infiltration. However, the site was located in an urban environment with limited land space, so an underground solution was needed. Complicating matters was the site was tucked in the corner of the property and access to the site was limited. In addition, the proposed retention system was located under a driving lane on the property, subjecting it to constant vehicle loading.

To tackle these issues, engineers from Michael Brady Inc. selected the Terre Arch precast concrete system for stormwater retention and infiltration. Terre Arch is a modular, multi-chambered, precast concrete stormwater storage system engineered for underground installation. With a load-bearing rating of HS-25, each section can support heavy gross weight trucks and machinery, allowing installation equipment direct access to the site during installation, dramatically reducing installation time and labor.

The engineers also liked that Terre Arch provides worker access from distribution boxes, providing confined space entry for removal of sediment and debris from inside the structure that is not possible with other chamber systems.

The contactor installed ten arches and two distribution boxes. Trucks arrived carrying two arches per load, and they were unloaded and installed quickly. Because of space limitations, the crane had to be repositioned several times, resulted in a slightly longer installation time for this particular site.

Technical Description:

  • (10) Terre Arch® 48 chambers
  • (2) Distribution boxes with risers

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