Home > FAQs > Will the sediment basin be lined and, if not, will the basins be in groundwater from 4 or 5 feet below existing ground level and below? Does DCA expect the slurry walls to keep them out of the groundwater?
The bottom of the sedimentation basins at the intakes would be located below the groundwater elevation. As described at the January 22, 2020, SEC meeting, the intakes, including the sediment basins, would be surrounded by a slurry wall. Slurry walls would serve to isolate the sediment basin volume from the surface water and groundwater to minimize the potential for seepage either into or out of the sedimentation basin. Based upon the geological information available for the intake locations, it appears that there are adequate clay lenses below the bottom of the sedimentation basin to isolate the intakes from surrounding groundwater. Therefore, it is currently not anticipated that the basins would require lining except for placement of riprap along the sides. Additional geotechnical investigations would be completed prior to design. The determination to provide linings for the basin would be based upon the additional geotechnical investigations.