Section 40.0902 - Purpose of the Risk CharacterizationA characterization of the risk of harm to health, safety, public welfare and the environment is performed at disposal sites to provide the quantitative and qualitative information used to evaluate the need for remedial actions:
(1) Risk Characterization is used to identify and evaluate site conditions which may pose an Imminent Hazard. The methodology used in this evaluation is described in 310 CMR 40.0950.(2) Risk Characterization is used to establish whether a level of No Significant Risk exists or has been achieved at a disposal site. The criteria used in this determination are described in 310 CMR 40.0900, and two basic approaches to Risk Characterization are utilized: (a) A chemical-specific approach, which compares site concentrations to standards in soil and groundwater, as described in 310 CMR 40.0970 through 40.0989. For the disposal sites to which they are applicable, these standards have been developed to meet the same objectives of the cumulative risk approach described in 310 CMR 40.0902(2)(b).(b) A cumulative risk approach which compares site-specific information to a Cumulative Cancer Risk Limit of an Excess Lifetime Cancer Risk of one-in-one hundred thousand, a Cumulative Noncancer Risk Limit which is a Hazard Index equal to one, promulgated health, safety, public welfare and environmental standards, and site-specific conditions, as described in 310 CMR 40.0990 through 310 CMR 40.0999.(3) If the concentration of an oil and/or hazardous material at the disposal site is at or below background levels, then that oil and/or hazardous material need not be included in the disposal site Risk Characterization. Disposal sites at which all oil and hazardous material have been reduced to background levels are eligible for a Permanent Solution, as described in 310 CMR 40.1041, even if such background levels exceed one or more of the numerical standards or risk criteria published in 310 CMR 40.0900.(4) The results of the Risk Characterization shall be the basis for a decision whether a remedial action is necessary and to select the appropriate Permanent or Temporary Solution for the disposal site pursuant to 310 CMR 40.1000.(5) "Screening" Risk Characterizations may be performed using worst-case exposure assumptions to quickly demonstrate that a condition of No Significant Risk exists or has been achieved at a disposal site. If such a conclusion cannot be reached following a screening Risk Characterization, a more detailed assessment is appropriate.Amended by Mass Register Issue 1503, eff. 3/1/2024.Amended by Mass Register Issue S1516, eff. 3/1/2024.