Q509. What is the definition of “facility” for underground storage?

A509. A “facility”, as defined in 40 CFR 98.6, must determine if it contains any of the industry segments listed in subpart W and compare its emissions against the 25,000 mtCO2e threshold defined in 40 CFR 98.2(a)(2) to determine applicability.  Underground natural gas storage is as defined in §98.230(a)(5) and includes reporting of GHGs as listed in §98.232(f)(1) through (5).  Therefore, the reporter needs to determine all applicable sources as per this industry segment definition and sources to report.  Specifically, filters and separators are not listed as sources under 98.232(f)(1) through (5) but if filters or separators are associated with any sources under this section, reporting of those listed sources is still required.  The sources required to report under the underground storage source category are listedin §98.232(f).  In this list dehydration units are not included therefore reporting from this source type is not required.