N.M. Admin. Code § 20.5.120.2002

Current through Register Vol. 35, No. 23, December 10, 2024

Section 20.5.120.2002 - MINIMUM SITE ASSESSMENT, INITIAL ABATEMENT

A. Owners and operators shall undertake the initial abatement and site investigation actions specified in this section within 72 hours of discovery or confirmation of a release pursuant to 20.5.118 NMAC, using the default timeline as set forth in Subsection E of 20.5.120.2000 NMAC or as otherwise approved by the department.

B. Owners and operators shall identify the location and details of construction of all private water supply wells, using readily accessible public records, within a 1,000-foot radius, and all public water supply wells within a one mile radius of the UST system, and shall determine if the identified wells lie within a designated wellhead protection area. Owners and operators shall take appropriate measures to protect these water supplies from contamination.

C. Owners and operators shall contain or remediate releases which present an imminent threat of contamination to or are within 500 feet of a surface water course as soon as practicable to prevent contamination of surface water. If the surface water course is a drinking water supply, within 24 hours owners and operators shall notify the owners or operators of all drinking water supplies likely to be affected by the release.

D. If the release has contaminated a water supply, owners and operators shall immediately provide a temporary replacement drinking water supply, as well as adequate warnings or other mechanisms to prevent persons from drinking or otherwise contacting water contaminated by the release. Within seven days of discovery or confirmation of a release pursuant to 20.5.118 NMAC that has contaminated a water supply, owners and operators shall provide a replacement water supply which is of adequate quality and quantity for drinking, bathing, cooking and washing. Owners and operators shall maintain the replacement water supply until an alternate water supply sufficient for all domestic purposes is available.

E. Owners and operators shall identify the depth, location, composition and construction of all underground utilities including water lines, sewer lines, communication cables, electric lines, and natural gas lines within the area of the release to assess the susceptibility of these utilities to permeation by contaminants or deterioration caused by contaminants. Owners and operators shall notify the utility owner that the release has occurred and obtain permission to perform a site check of the utilities or other subsurface structures most likely to be contaminated by the release to determine whether NAPL or vapors are present.

F. Owners and operators shall complete an investigation to determine whether potentially explosive or harmful vapors are present in any building, utility corridor, basement, or other surface or subsurface structure on or adjacent to the release site.

(1) The investigation shall include testing for vapors using the following:

(a) a combustible gas indicator or equivalent instrument calibrated according to the manufacturer's instructions to test for potentially explosive levels of vapors; and

(b) a photoionization detector, flame ionization detector or another method approved by the department calibrated according to the manufacturer's instructions to test for potentially harmful vapors.

(2) In the event owners and operators discover potentially explosive levels of vapors greater than 10 percent of the lower explosive limit (LEL) or potentially harmful vapors reading greater than five whole units above ambient concentrations in any structure in the vicinity of the release site, owners and operators shall take immediate action to mitigate the vapor hazard. Within seven days of the discovery of the vapors, owners and operators shall install and place into operation a vapor mitigation system capable of reducing vapors to safe levels within the shortest reasonable time. The vapor mitigation system shall be designed by and constructed under the direct, responsible, supervisory control of a professional engineer, when required by the department.

(a) Once a vapor mitigation system has been installed, owners and operators shall monitor and report in writing to the department the levels of vapors in the affected structures weekly for the first month and monthly thereafter unless a different monitoring schedule is approved in writing by the department. This monitoring shall be performed in accordance with Subparagraphs (a) and (b) of Paragraph (1) of this subsection.

(b) After the vapor mitigation system has been in operation for three months, owners and operators shall have 30 days to submit to the department a written summary report containing the monitoring results. The department may direct owners and operators to modify the vapor mitigation system as necessary to reduce vapors to safe levels. Owners and operators shall submit monitoring results to the department at three-month intervals until operation of the vapor mitigation system is discontinued in accordance with this section.

(3) Owners and operators shall continue to operate the vapor mitigation system until the results of three consecutive monthly monitoring events indicate the following:

(a) levels of vapors are less than ten percent LEL; and

(b) levels of vapors are less than or equal to five whole instrument units above ambient levels in any structure in the vicinity of the release site when measured as required in Subparagraphs (a) and (b) of Paragraph (1) of this subsection.

(4) When operation of a vapor mitigation system is discontinued, owners and operators shall monitor the vapor levels in the structure weekly for the first month and monthly thereafter until one calendar year has passed, or as otherwise approved by the department. If during this period the levels exceed those set forth in Subparagraphs (a) and (b) of Paragraph (3) of this subsection, owners and operators shall notify the department and take the necessary corrective action, as directed by the department.

G. Owners and operators shall remove any exposed hazardous substances related to the release and mitigate any related immediate fire and safety hazards as soon as possible, but in no case no later than 72 hours after the confirmation or other identification of the release.

N.M. Admin. Code § 20.5.120.2002

Adopted by New Mexico Register, Volume XXIX, Issue 14, July 24, 2018, eff. 7/24/2018