N.M. Admin. Code § 20.5.119.1921 - COMPLETION OF MONITORED NATURAL ATTENUATION

A. Natural attenuation shall be considered complete when all of the following criteria are met:

(1) no layer of NAPL greater than one-eighth inch in thickness is present on the water table or in any of the wells;

(2) the EIB standard of 0.1 mg/L for methyl tertiary butyl ether (MTBE) has been met in groundwater and surface water;

(3) all applicable site-specific target levels or risk-based screening levels in soil and WQCC and EIB standards in groundwater have been achieved:

(a) the applicable standards shall be achieved concurrently at all compliance wells as approved by the department;

(b) for verification that soil has reached target concentrations, owners and operators shall install at least four soil borings, at least three of which are distributed throughout the previously most contaminated portion of the vadose zone, unless otherwise approved by the department;

(4) corrective action requirements for total petroleum hydrocarbons determined in accordance with 20.5.119.1914 NMAC have been met; and

(5) any other conditions which threatened public health, safety and welfare or the environment have been abated.

B. If any of the conditions of Paragraphs (1) through (5) of Subsection A of this section are not met, the department may require owners and operators to perform additional remediation.

C. Termination of monitored natural attenuation in accordance with this section does not relieve the owner and operator of any other liability or responsibility they may have under this part or any other federal, state or local law or regulation.

D. Following department approval, and with 30 days' notice unless otherwise approved by the department, owners and operators shall properly abandon wells that are no longer needed for monitoring, in accordance with federal, state and local laws and regulations.

Notes

N.M. Admin. Code § 20.5.119.1921

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