Section 40.0982 - General Approach to Method 2A Method 2 Risk Characterization supplements and modifies the MCP Method 1 Standards with site-and chemical-specific information. For the purposes of 310 CMR 40.0000, "MCP Method 2 Standards" shall refer to the MCP Method 1 Standards which have been modified to address site-specific conditions as described in 310 CMR 40.0982. Site conditions are then compared to such MCP Method 2 Standards, in the same manner that MCP Method 1 Standards are used under 310 CMR 40.0973, to characterize the risk of harm to health, public welfare and the environment.
(1) MCP Method 1 GW-1 Standards shall not be modified in Method 2. These standards are listed in 310 CMR 40.0974(2).(2) The component of the MCP Method 1 Soil Standards which is protective of direct contact exposures to the soil shall not be modified in Method 2. These standards are listed in 310 CMR 40.0985(6).(3) The following information may be used under Method 2 to modify the Method 1 Standards: (a) MCP Method 2 Groundwater and Soil Standards may be developed for chemicals for which MCP Method 1 Standards have not been promulgated by the Department. This process is described in 310 CMR 40.0983 and 310 CMR 40.0984.(b) Site-specific information may be used to either modify the leaching component of the MCP Method 1 Soil Standards or to demonstrate that a contaminant will not leach to groundwater. The incorporation of such site-specific information will result in MCP Method 2 Soil Standards or a determination that the leaching component of one or more Method 1 soil standard is not applicable. These site-specific modifications are described in 310 CMR 40.0985.(c) Site-specific information may be used to either modify the MCP Method 1 GW-2 Standards, which model potential volatilization of oil and/or hazardous material to indoor air, or to demonstrate that such vapor infiltration will not occur. The incorporation of such site-specific information will result in MCP Method 2 GW-2 Standards or a determination that one or more Method 1 GW-2 standard is not applicable at this site. These site-specific modifications are described in 310 CMR 40.0986.(d) Site-specific information may be used to either modify the MCP Method 1 GW-3 Standards, which are set to be protective of potential discharges of oil and/or hazardous material to surface water, or to demonstrate that such discharges will not occur. The incorporation of such site-specific information will result in MCP Method 2 GW-3 Standards or a determination that one or more Method 1 GW-3 standard is not applicable. These sitespecific modifications are described in 310 CMR 40.0987.(4) If the modification of a MCP Method 1 GW-2 or GW-3 Standard results in a concentration of an oil and/or hazardous material greater than the Method 3 Ceiling Limit in Groundwater listed in 310 CMR 40.0996(7), then the Method 3 Ceiling Limit for that chemical shall be used to characterize the risk of harm to health, public welfare and the environment in Method 2.(5) MCP Method 1 Standards may be used in combination with one or more MCP Method 2 Standards. A Risk Characterization which uses a combination of MCP Method 1 and 2 Standards shall be considered a Method 2 Risk Characterization.(6) The MCP Method 2 Standards developed and used or relied upon by the LSP shall be listed and suitably documented.(7) The Department may develop and publish sets of chemical-specific concentrations which, for specific types of disposal sites, will demonstrably meet the Risk Characterization requirements described at 310 CMR 40.0990. Such concentrations may be used at the RP's, PRP's or Other Person's option to characterize risk at a disposal site, and the use of these sets of concentrations shall be considered a Method 2 Risk Characterization.Amended by Mass Register Issue 1503, eff. 3/1/2024.Amended by Mass Register Issue S1516, eff. 3/1/2024.