Deriving Drinking Water Resources for Unusually Sensitive Areas

ABSTRACT The Research and Special Programs Administration (RSPA) of the Department of Transportation is required to identify areas that are unusually sensitive to environmental damage in the event of a hazardous liquid pipeline accident, in accordance with pipeline safety laws (49 U.S.C. Section 60109). Accordingly, workshops were held with regulatory agencies, pipeline operators, and the public during which a process was developed to identify “unusually sensitive areas” (USAs) for drinking water resources. This process, which has been adopted by RSPA, consists of first identifying environmentally sensitive drinking water resources and other primary concerns, and then applying the following five filtering criteria to determine which of the drinking water source locations should be USAs:, Filter Criterion #1. If the public water system is a Transient Noncommunity Water System (TNCWS), the water intakes shall not be designated as USAs. Filter Criterion #2. For Community Water Systems (CWS) and Nontransient Noncommunity Water Systems (NTNCWS) that obtain their water supply primarily from surface water sources, and do not have an adequate alternative source of water, the water intakes shall be designated as USAs. Filter Criterion #3. For CWS and NTNCWS that obtain their water primarily from ground water sources, where the source aquifer is identified as a Class I or Class IIa, as defined in Pettyjohn et al. (1991), and do not have an adequate alternative source of water, these wells shall be designated as USAs. The wellhead protection area for each well will be used to define the area of the USA. Filter Criterion #4. For CWS and NTNCWS that obtain their water primarily from ground water sources, where the source aquifer is identified as a Class IIb, IIc, III, or U, as defined in Pettyjohn et al. (1991), these wells shall not be designated as USAs. Filter Criterion #5. For CWS and NTNCWS that obtain their water primarily from ground water sources, where the source aquifer is identified as a Class I or Class IIa, as defined in Pettyjohn et al. (1991), and the aquifer is designated as a sole source aquifer, these wells are also USAs, an area twice the wellhead protection area shall be designated as a USA.