How will this facility be kept operational once it is constructed considering the amount of dewatering that needs to occur?

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June 15, 2020

After construction, the water level in the facility would be higher than the surrounding groundwater. Also, the site would be surrounded by a slurry cutoff wall. Based upon existing geotechnical information, it is anticipated that the slurry walls would be extended to clay lenses to essentially isolate the site from surrounding surface water and groundwater. Dewatering would be expected to be a more significant issue during the early construction phases than during the operation phases. DCA is currently evaluating the estimated dewatering needs to maintain groundwater levels suitable for construction. DCA is also currently evaluating estimates for operational dewatering needs, which will be limited to periodically dewatering the basins for infrequent maintenance. At this time, only limited geotechnical data is available near the intake sites. Additional geotechnical investigations would be completed prior to design. Final determinations for protecting the sites from seepage into or out of the site and to quantify the dewatering needs would be revised following the geotechnical investigations.

Is there a possibility that the geotechnical reports DWR is currently conducting could change where the intakes are located?

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?