Arizona Administrative Code › Title 18 - ENVIRONMENTAL QUALITY › Chapter 12 - DEPARTMENT OF ENVIRONMENTAL QUALITY - UNDERGROUND STORAGE TANKS › Article 2 - TECHNICAL REQUIREMENTS › Section R18-12-263.01 - Risk-based Corrective Action Standards

Current through Register Vol. 30, No. 28, July 12, 2024
A. Conducting risk-based tier evaluation and
				proposing the applicable corrective action standard. The owner or operator
				shall propose and document, as described in subsection (B), each applicable
				risk-based corrective action standard, using the procedures of this subsection.
				The owner or operator shall ensure that each corrective action standard meets
				the corrective action requirements of A.R.S. §
									49-1005(D) and
				(E), and is consistent with soil remediation
				standards and restrictions on property use in A.R.S. Title 49, Chapter 1,
				Article 4 and the rules made under each. In determining the proposed corrective
				action standard, the owner or operator shall first perform a Tier 1 evaluation.
				The owner or operator may subsequently perform progressively more
				site-specific, risk-based tier evaluations (Tier 2 or Tier 3) after considering
				the comparative differences in input parameters, the cost effectiveness in
				conducting both the additional evaluation and remediation to the next tier
				corrective action standard, and the cumulative estimate of risk to public
				health and the environment.
1. For a Tier 1
				evaluation, the owner or operator shall:
a.
				Base assumptions on conservative scenarios where all potential receptors are
				exposed to the maximum concentration of each chemical of concern in each
				contaminated medium detected in contamination at and from the LUST
				site;
b. Assume that all exposure
				pathways are complete;
c. Use the
				assumed point of exposure at the source or the location of the maximum
				concentration as the point of compliance;
d. Compare the maximum concentration of each
				chemical of concern in each contaminated medium at the point of compliance with
				the applicable Tier 1 corrective action standard in subsections (A)(1)(e)
				through (A)(1)(j);
e. For soil, use
				the applicable corrective action standard in
				R18-7-203(A)(1)
				and (2) and (B);
f. For surface water, use the applicable
				corrective action standard in
				R18-11-112
				or Appendix A (18 A.A.C. 11, Article 1);
g. For groundwater, use the applicable
				corrective action standard in
				R18-11-406;
h. For contaminated groundwater that is
				demonstrated to discharge or potentially discharge to surface water, use the
				applicable corrective action standard in
				R18-11-108,
				R18-11-112,
				or Appendix A (18 A.A.C. 11, Article 1);
i. If a receptor is or has the potential to
				be impacted, for those chemicals of concern in soil or surface water with no
				numeric standard established in rule or statute, use a corrective action
				standard consistent with
				R18-7-206
				or
				R18-11-108,
				as applicable, using updated, peer-reviewed scientific data applying those
				equations and methodologies used to formulate the numeric standards established
				in R18-7-203(A)(2) or Appendix A (18 A.A.C. 11, Article 1), or for leachability
				and protection of the environment, a concentration determined on the basis of
				methods approved by the Department; and
j. If a public or private water supply well
				is or has the potential to be impacted, for those chemicals of concern in
				groundwater with no numeric water quality standard established in rule or
				statute, use a corrective action standard consistent with
				R18-11-405,
				using updated, peer-reviewed scientific data applying those equations and
				methodologies used to formulate the numeric standards established in
				R18-11-406.