Hoekstra Slurry Wall

Project Location: Longmont, Colorado

Project Description:

This design-build project included two separate soil-bentonite cutoff walls (also referred to as slurry walls) near the St. Vrain River Basin in Weld County. The first cutoff wall surrounded two cells and was 5,887 LF with an average depth of 20 FT to bedrock. The second cutoff wall surrounded one cell and was 4,358 LF with an average depth of 20 FT to bedrock. In addition to these cutoff walls, we also lined a fourth cell using clay material from the bottom of the mined pit to construct a 5,360 LF clay liner with an average depth of 20 FT.

To complete this water storage project, we also constructed concrete lined ditches throughout the site in order to convey the water from the various cells to the river. This included diversion structures throughout the ditch structure. These lined cutoff walls also had an underdrain system to compensate for the mounding effect created by the lined cells. Additionally, Hall-Irwin constructed the wet well, diversion structure from the wet well and all of the supporting conveyance equipment from the wet well to the river. This allowing the client to install a future pump when ready.