310 CMR, § 30.666
The Department shall specify, in the facility's license, those specific hazardous constituents identified in 310 CMR 30.161 to which the requirements of 310 CMR 30.665: Groundwater Protection Standard shall apply. The Department shall identify such hazardous constituents upon establishing a compliance monitoring or corrective action program in the facility's license. Hazardous constituents which shall be specified in the license shall be constituents identified in 310 CMR 30.160 that the Department reasonably expects to be in or derived from waste contained in a regulated unit. The Department may exclude such a constituent from the list of hazardous constituents in the facility's license if the constituent is unstable in water and has not been detected in the groundwater.
310 CMR, § 30.666