18 AAC 78.235 - Release investigation

(a) After meeting the requirements of 18 AAC 78.220 and 18 AAC 78.230, the owner or operator of a UST with a confirmed release of petroleum shall perform a release investigation to characterize the release and actual or potential threat to human health and safety, and to the environment. If applicable to the site, an investigation under this section must include the following:

(1) soil samples, sufficient in number and location to represent the conditions of the soil, must be taken to adequately characterize the horizontal and vertical distribution of the release in the soil and to identify soil properties that are likely to influence the type and rate of migration of the released petroleum;

(2) sample collection and other investigations of the site geology and hydrogeology must be conducted to adequately characterize the horizontal and vertical distribution of the release in groundwater and those features that affect the fate and transport of the petroleum; if groundwater contamination is confirmed, the owner or operator shall notify the department within 24 hours and identify public and private drinking water wells that are located within one-quarter mile of the release site;

(3) sample collection and other investigations of surface waters must be conducted to adequately characterize significant hydrologic features such as surface drainage patterns and quantities, surface waters, floodplains, and actual or potential contaminant migration routes toward or within these features;

(4) a hazard ranking evaluation must be conducted to measure the potential risk to human health and safety, and to the environment; data collected must include information on toxicity and quantity of the contaminants, release information, site access, air exposure, surrounding populations, water use and exposure, surrounding environmental and recreation areas, and observed environmental impacts; the hazard ranking evaluation must be submitted on a form provided by the department; and

(5) a sampling and analysis plan must be submitted to and approved by the department, if the owner or operator plans to use a statistical method referenced in 18 AAC 78.276(e) for site closure and final compliance with the soil cleanup levels under 18 AAC 78.600 - 18 AAC 78.610.

(b) The collection and interpretation of field data and the reporting of release investigation data must be conducted or supervised by a qualified environmental professional in accordance with the UST Procedures Manual.

(c) Repealed 6/17/2015.

(d) Laboratory analyses submitted to fulfill the requirements of this section must be performed by a laboratory approved by the department under 18 AAC 78.800 - 18 AAC 78.815.

(e) After completing a release investigation required under this section, the owner or operator shall undertake corrective action as prescribed in 18 AAC 78.240 - 18 AAC 78.276 unless directed by the department to do otherwise as necessary to ensure protection of human health or safety, or of the environment.

(f) In a release investigation, the owner or operator shall use the analytical methods set out in Table 1, Chapter 2 of the UST Procedures Manual.

(g) Within 45 days after the date of release confirmation, as established under (h) of this section, the owner or operator shall submit a release investigation report to the department, summarizing the initial abatement measures conducted under 18 AAC 78.230 and including

(1) the owner's name and address;

(2) the operator's name and address, if different from the owner;

(3) the location of the UST, including the legal description by

(A) subdivision lot, block, or tract information; or by section lot, tax lot, or government lot number; or

(B) meridian, township, range, section, and nearest quarter section locations within the section if the location cannot be described under (A) of this paragraph;

(4) the UST registration number assigned by the department;

(5) the name and business address of each person who supervised the release investigation;

(6) all sample analyses and test results received, reported as required in the UST Procedures Manual,Section 8.4;

(7) data on the nature and estimated amount of the release;

(8) data summarizing the hazard ranking evaluation conducted under (a)(4) of this section, on a form provided the department;

(9) information gained through soil, groundwater, geology, and surface water investigations conducted under this section;

(10) a narrative description of activities conducted at the site and the dates the activities occurred;

(11) a site sketch that approximately shows

(A) the location and configuration of tanks and piping;

(B) the sample locations, including depth below grade;

(C) the proximity to property, buildings, and residences;

(D) any sites where a release has occurred;

(E) any sites where free product has been or is located;

(F) the facility and property boundaries;

(G) a bar scale and north arrow; and

(H) any other pertinent information;

(12) a UST site history, including previous releases, repairs, spills, or corrective action activities; and

(13) an evaluation of the existence of petroleum vapors within any nearby occupied structure.

(h) The date of release confirmation is established by the earlier of the following events:

(1) the receipt, by the owner or operator, of a report under 18 AAC 78.090 or 18 AAC 78.210, if the report indicates petroleum contamination; or

(2) the owner's or operator's first observation, or first knowledge of an observation, of petroleum contamination.

Notes

18 AAC 78.235

Eff. 11/3/95, Register 136; am 1/22/99, Register 149; am 1/30/2003, Register 165; am 6/17/2015, Register 214, July 2015; am 7/1/2017,Register 222, July 2017

The hazard ranking evaluation form mentioned in 18 AAC 78.235(a)(4) is located in the department's UST Procedures Manual as Appendix E.

Authority:AS 46.03.020

AS 46.03.365