Section 58.01.08.323 - GROUND WATER RULE 40 CFR 141, Subpart S is incorporated by reference. "Implementation Guidance for the Drinking Water Program - Ground Water Rule," as referenced in Section 002, provides assistance to PWS owners and operators in understanding and achieving compliance with the requirements of 40 CFR 141, Subpart S.
01.Discontinuation of Treatment. PWSs that wish to discontinue four (4)-log virus treatment at a groundwater source must meet the following criteria. Groundwater sources on which treatment has been discontinued will be subject to the triggered source water monitoring requirements of 40 CFR 141, Subpart S. a. Demonstration that any known source of contamination has been removed.b. Demonstration that structural deficiencies of the well have been rehabilitated and no longer exist.c. Provide evidence that the well is drawing from a protected or confined aquifer.d. Submit results of one (1) year of monthly monitoring for a fecal indicator organism during which no positive results occurred.02.Chlorine Purging Prior to Triggered Source Sampling. 40 CFR 141.402(e) requires that groundwater source samples be collected at a location prior to any treatment. Pursuant to this requirement PWSs that add chlorine to a source, either in the well bore or near enough to the wellhead that chlorinated water may backflow into the well, must ensure that all chlorine residual has been purged prior to taking a triggered source water sample. This must be accomplished by measuring chlorine residual in the source water until a reading of zero is obtained and be recorded in the space provided for chlorine residual on the sample submittal form.Idaho Admin. Code r. 58.01.08.323