Rule 3745-535-860 | Groundwater remediation standards.
(A) The owner or operator shall establish a groundwater remediation standard for each waste-derived constituent detected at a statistically significant concentration in groundwater pursuant to rule 3745-535-820 of the Administrative Code as follows:
(1) For constituents with a maximum contaminant level specified in Chapter 3745-81 of the Administrative Code, the maximum contaminant level for that constituent.
(2) For constituents without a maximum contaminant level specified in Chapter 3745-81 of the Administrative Code, the background concentration for the constituent well established in accordance with paragraphs (D) and (E) of rule 3745-535-810 of the Administrative Code.
(3) An alternative groundwater remediation standard in accordance with paragraph (B) of this rule.
(B) The director may establish an alternative groundwater remediation standard for constituents without a maximum contaminant level. These groundwater remediation standards shall be appropriate health-based levels that satisfy the following criteria:
(1) The concentration level is derived in a manner consistent with federal guidelines for assessing the health risks of environmental pollutants.
(2) The concentration level is based on scientifically valid studies conducted in accordance with standard laboratory practices.
(3) For known or suspected carcinogens, the proposed concentration levels will be established at concentration levels below those that represent a cumulative (due to lifetime exposure) excess upper-bound lifetime cancer risk to an individual within the 1 x 10-4 to 1 x 10-6 range.
(4) For systemic toxicants, the proposed concentration levels will be reduced to levels to which the human population (including sensitive subgroups) could be exposed on a daily basis without appreciable risk of deleterious effects during a lifetime. For the purposes of this rule, "systemic toxicants" include toxic chemicals that cause effects other than cancer or mutation.
(5) For waste-derived constituents where the owner or operator has demonstrated to the director that the constituent is already present in the groundwater at background levels, the proposed concentration level will not be set below background levels unless the director determines that cleanup to levels below background is necessary to protect human health and the environment and such cleanup is in connection with an area-wide remedial action under other authorities.
(C) When establishing groundwater remediation standards in accordance with paragraph (B) of this rule, the director may consider the following:
(1) Multiple contaminants in the groundwater.
(2) Exposure threat to sensitive environmental receptors.
(3) Other site-specific exposure or potential exposure to groundwater.
(4) The reliability, effectiveness, practicability, and other relevant factors of the remediation procedure.
Last updated March 1, 2026 at 8:22 AM
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