Oregon Administrative Rules › Chapter 340 - DEPARTMENT OF ENVIRONMENTAL QUALITY › Division 122 - HAZARDOUS SUBSTANCE REMEDIAL ACTION RULES › Section 340-122-0243 - Low-Impact Sites

Current through Register Vol. 63, No. 7, July 1, 2024
Upon completion of all applicable requirements of OAR
				340-122-0205  through
				340-122-0240,
				a responsible person may propose closure of a facility as a low-impact site if
				information gathered during site investigations clearly demonstrates that site
				conditions have stabilized (i.e., significant future migration of contamination
				is unlikely) and that the site is likely to have low current and potential
				future impact on the basis of risk or impairment of beneficial land and water
				uses. The purpose of the low-impact site designation is to provide a
				streamlined process for operating gas stations or other industrial or
				commercial properties that allows these facilities to remain in operation while
				the responsible person manages any potential risk from contamination remaining
				at the site. If the Department develops a generic remedy for low-impact sites
				in accordance with OAR
				340-122-0252,
				then the low-impact site requirements specified in this rule (OAR
				340-122-0243) 
				will no longer be in effect. Until such time as a low-impact site generic
				remedy is in effect, the steps for low-impact closure are described
				below.
(1) The site must meet each of
			 the following conditions:
(a) The source of
			 the release has been repaired or removed, and all tanks, lines, and associated
			 equipment at the site have been upgraded to meet applicable technical and
			 regulatory standards.
(b) The
			 facility must continue to be used as a gas station or other industrial or
			 commercial use precluding potential routine exposure to children.
(c) Other than minimal amounts of petroleum
			 product in the tank pit at the time of tank removal, no measurable free product
			 was found on the groundwater.
(d)
			 Concentrations of gasoline in the contaminated soil should not exceed 1000 ppm
			 TPH, and concentrations of diesel and other non-gasoline fraction hydrocarbon
			 in the contaminated soil should not exceed 10,000 ppm TPH.
(e) Contaminated soil remaining at the site
			 should not be located within 3 feet of the land surface, unless:
(A) Contaminant concentrations do not exceed
			 generic risk-based concentrations for direct contact developed in accordance
			 with OAR
			 340-122-0252;
			 or
(B) Department-approved
			 institutional or engineering controls have been implemented and will be
			 maintained to prevent direct contact with soils.
(f) Contamination is not located in utility
			 corridors, unless:
(A) The contamination is
			 shown to have been stabilized and is unlikely to result in vapor or groundwater
			 problems;
(B) Contaminant
			 concentrations do not exceed generic risk-based concentrations for a trench
			 worker scenario developed in accordance with OAR
			 340-122-0252;
			 and
(C) The corresponding utility
			 has been notified of the contamination.
(g) Service station and other nonresidential
			 buildings must not be located over or within 10 lateral feet and residences
			 must not be located over or within 50 lateral feet of contaminated soil,
			 unless:
(A) Contaminant concentrations do not
			 exceed generic risk-based concentrations for volatilization from soils into
			 buildings developed in accordance with OAR
			 340-122-0252;
			 or
(B) It is demonstrated that
			 potential exposure from volatilization into buildings from this contamination
			 does not exceed acceptable risk levels; or
(C) Department-approved actions have been
			 taken to mitigate potential vapor problems.
(h) If groundwater contamination is found at
			 the site:
(A) There are no water supply wells
			 located within one-quarter mile of the source of contamination;
(B) The groundwater plume is less than 250
			 feet in length as measured from the center of the source;
(C) Monitoring data are available to
			 demonstrate that the groundwater plume has stabilized, or is diminishing in
			 size;
(D) The groundwater plume
			 does not leave the source property at concentrations exceeding generic
			 risk-based concentrations developed in accordance with OAR
			 340-122-0252,
			 unless owners of other affected properties consent to institutional or
			 engineering controls necessary to prevent exposure due to the contaminated
			 groundwater; and
(E) Service
			 station and other nonresidential buildings must not be located over or within
			 10 lateral feet and residences must not be located over or within 50 lateral
			 feet of contaminated groundwater, unless:
(i)
			 Contaminant concentrations within the plume do not exceed generic risk-based
			 concentrations for volatilization from groundwater into buildings developed in
			 accordance with OAR
			 340-122-0252;
			 or
(ii) It is demonstrated that
			 potential exposure from volatilization into buildings from this contamination
			 does not exceed acceptable risk levels; or
(iii) Department-approved actions have been
			 taken to mitigate potential vapor problems.