STATEWIDE GROUNDWATER ADVISORY ON SEALING MATERIAL FOR WELLS

October 3, 2015 (San Diego’s East County)--The California Department of Water Resources (DWR) has issued a statewide advisory to inform well drillers, local enforcing agency staff and others against using bentonite slurries as a sealing material for well construction.

In an effort to increase protection of our groundwater resources, a multi-year study of grout performance, conducted by the Nebraska Grout Task Force, found that bentonite slurries do not perform adequately as a sealing material in the unsaturated zone in California.

With an increase of well-drilling activities in response to drought and declining groundwater levels, this advisory against using bentonite slurries as a sealing material, comes from both DWR and Groundwater Resources Association of California (GRA).

“Bentonite slurries can shrink and crack when they dry out, and they do not adequately hydrate and swell once water is reintroduced to the seal,” stated a DWR advisory.

While the California Well Standards currently includes bentonite slurries, the DWR plans to update these standards.

GRA president Ted Johnson noted, “GRA will continue to be engaged at the State level to review and provide comment on the wise protection and preservation of California’s precious groundwater resources, and we encourage you to do the same.”