Or. Admin. Code § 340-122-0243

Current through Register Vol. 63, No. 10, October 1, 2024

Section 340-122-0243 - Low-Impact Sites

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.

(2) The responsible person must implement institutional or engineering controls, in a form acceptable to the Department, necessary to ensure that a site's designation as a low-impact site remains unchanged.

(3) The responsible person must submit a low-impact-site-closure report to the Department that includes the following:

(a) A site summary with appropriate scaled maps, a discussion of current and reasonably likely future land uses for the site and adjacent properties, including information from local government comprehensive planning plans and zoning ordinances, and information on geology, hydrogeology, topography, and other relevant factors on which the low-impact closure is based.

(b) Information about the release, including a history of all actions taken, data from all samples collected at the site, and a description of all contamination, including scaled maps showing the locations of contamination that was treated or removed from the site and contamination remaining at the site at the time of the report.

(c) Sufficient discussion and supporting data to address each of the specific low-impact site requirements listed in section (1) of this rule.

(d) If groundwater contamination is present at concentrations exceeding generic risk-based concentrations, a discussion of current and reasonably likely future water uses.

(e) If groundwater contamination is present at concentrations exceeding generic risk-based concentrations and the site is located within a certified drinking water protection area (DWPA), a description of the DWPA and what additional information has been gathered and measures taken to ensure that there are no current or potential future adverse impacts to the groundwater in the aquifer within the DWPA.

(f) A proposal, subject to Department approval, for any institutional or engineering controls necessary to maintain low-impact site conditions.

(4) Upon review of the low-impact site closure report, the Department may:

(a) Approve the report and, upon receipt of adequate documentation showing that any necessary institutional or engineering controls have been implemented and will be maintained, issue a low-impact site closure letter stipulating the site conditions that must be maintained;

(b) Request that additional information be submitted or work be performed in support of the proposed low-impact closure; or

(c) Determine that the site does not meet the conditions for low-impact closure and require that additional actions be taken under other relevant sections of OAR 340-122-0205 through 340-122-0360.

(5) The Department shall require public notice consistent with applicable requirements of OAR 340-122-0260 for sites proposed for low-impact closure.

(6) The owner of any property requiring controls under this rule must notify the Department of any future changes that might affect the facility's designation as a low-impact site.

Or. Admin. Code § 340-122-0243

DEQ 23-1998, f. & cert. ef. 11-2-98

Stat. Auth.: ORS 465.400 & ORS 466.746

Stats. Implemented: ORS 465.200 - ORS 465.455 & ORS 466.706 - ORS 466.835