Section 30.667 - Concentration Limits(1) If the Department specifies in a facility's license a compliance monitoring program or a corrective action program, the Department shall also specify in the facility's license concentration limits, established pursuant to 310 CMR 30.666, for hazardous constituents in the groundwater. The concentration of a hazardous constituent: (a) Shall not, at the time that such limit is specified in the license, exceed the background level of that constituent in the groundwater; or(b) For any of the constituents listed in 310 CMR 30.000: Table 30.668, shall not exceed the respective maximum concentration set forth in 310 CMR 30.000: Table 30.668 if the background level of the constituent is below the value set forth in 310 CMR 30.000: Table 30.668; or(c) Shall not exceed an alternate limit established by the Department pursuant to 310 CMR 30.667(2).(2) The Department may establish an alternate concentration limit for a hazardous constituent if the Department determines that the constituent will not pose a substantial present or potential hazard to public health or safety or the environment as long as the alternate concentration limit is not exceeded. In establishing each alternate concentration limit, the Department shall consider the following factors:(a) Potential adverse effects on groundwater quality, considering: 1. The physical and chemical properties of the waste in the regulated unit, including its potential for migration;2. The hydrogeologic characteristics of the facility and surrounding land;3. The quantity of groundwater and the direction of groundwater flow;4. The proximity and withdrawal rates of groundwater users;5. The current and potential uses of groundwater in the area;6. The existing quality of groundwater, including other sources of contamination and their cumulative impact on the groundwater quality;7. The potential for health or safety risks caused by human exposure to waste constituents;8. The potential damage to wildlife, crops, vegetation, and physical structures caused by exposure to waste constituents;9. The persistence and permanence of the potential adverse effects; and(b) Potential adverse effects on hydraulically-connected surface water quality, considering: 1. The volume and physical and chemical properties of the waste in the regulated unit;2. The hydrogeologic characteristics of the facility and surrounding land;3. The quantity and quality of groundwater, and the direction of groundwater flow;4. The patterns of rainfall in the region;5. The proximity of the regulated unit to surface water(s);6. The current and potential uses of surface water(s) in the sources of contamination and the cumulative impact on surface water quality;7. The existing quality of surface water, including other sources of contamination and the cumulative impact on surface water quality;8. The potential for health or safety risks caused by human exposure to waste constituents;9. The potential damage to wildlife, crops, vegetation, and physical structure caused by exposure to waste constituents; and10. The persistence and permanence of the potential adverse effects.(3) In making any determination, pursuant to 310 CMR 30.667(2), about the use of groundwater in the area around the facility, the Department shall consider any identification, made pursuant to 310 CMR 27.00: Underground Water Source Protection, of underground sources of drinking water and exempted aquifers.