05/02/2018 - DEQ Tightens Groundwater-Surface Water Interface Standards for Dioxane

At the 05/01/2018 CARD meeting, the DEQ revealed that its groundwater-surface water interface (GSI) standards for 1,4-dioxane had been tightened in March 2018*.

The good news is that for groundwater projected to vent to surface water that is used as a drinking water source, the GSI standard tightened from 34 ppb to 3.5 ppb... and for groundwater projected to vent to surface water that is not used as a drinking water source, the GSI standard tightened from 2800 ppb to 280 ppb.

The bad news is that the DEQ says these new standards will not affect the Gelman dioxane groundwater contamination as long as the current Consent Judgment is in effect.

With a more protective Consent Judgment, much more dioxane would have to be removed in the well Prohibition Zone before the dioxane reaches surface water.

* The news of the change had been announced through the DEQ's overall listserv but not passed on via its Gelman Site listserv. The DEQ acknowledged that it probably should have relayed the announcement to the Gelman site email list and would try to do so with and similar announcements in the future.