Section 40.0987 - Determination of MCP Method 2 GW-3 Standards(1) MCP Method 1 GW-3 Standards consider potential migration of oil and/or hazardous material to surface water. These standards may be modified under Method 2 based upon sitespecific conditions to develop MCP Method 2 GW-3 Standards or it may be determined that a discharge to surface water will not occur. The proposed Method 2 modification shall be scientifically justified and sufficiently documented to demonstrate that the Response Action Performance Standard, described in 310 CMR 40.0191, has been met.(2) An MCP Method 2 GW-3 standard or determination shall be protective of migration of oil and/or hazardous material into surface waters and wetlands. The presence of an oil and/or hazardous material in the groundwater must not result in concentrations in a surface water or wetland which would pose a significant risk of harm to health, public welfare or the environment. The MCP Method 2 GW-3 Standard may be greater or less than the corresponding MCP Method 1 GW-3 Standard, or it may be determined that the Method 1 GW-3 standard is not applicable, considering site-specific conditions. The development of such standards or such a determination shall be documented by:(a) transport and fate modeling that incorporates site-specific information on the source and subsurface hydrological conditions, and which demonstrates that the release will not result in concentrations of oil and/or hazardous material in the receiving surface water which exceed any applicable or suitably analogous standards described in 310 CMR 40.0993(3), and which do not otherwise result in a significant risk of harm to health, safety, public welfare or the environment; and/or(b) long-term groundwater monitoring which demonstrates that the release will not result in concentrations of oil and/or hazardous material in the receiving surface water which exceed any applicable or suitably analogous standards described in 310 CMR 40.0993(3), and which do not otherwise result in a significant risk of harm to health, safety, public welfare or the environment. The duration of required monitoring would depend on the source mass, the mobility of the oil and/or hazardous material, and subsurface conditions.Amended by Mass Register Issue 1407, eff. 12/27/2019.Amended by Mass Register Issue 1503, eff. 3/1/2024.Amended by Mass Register Issue S1516, eff. 3/1/2024.