Notes
Implementation Memo No. 3 dated November 24, 1993, from Steve Robb of the Washington State Department of Ecology Toxics Cleanup Program to Interested Staff, addressing two issues regarding practical quantitation limits (PQLs) as cleanup standards under the Model Toxics Control Act (MTCA). Covers long-term liability for potentially liable persons (PLPs) who clean up to PQL levels rather than risk-based levels under WAC 173-340-700(6) and WAC 173-340-707(2), eligibility for covenant not to sue, institutional controls, long-term monitoring requirements, and periodic review with reopener provisions. Also addresses risk summation calculations when risk-based compliance values are less than PQLs, including the 1×10-5 and 1×10-6 cumulative site risk thresholds, special analytical methods under WAC 173-340-707(3), and risk communication requirements in Cleanup Action Plans (CAPs). References trichloroethylene (TCE) groundwater cleanup level of 3.98 ppb and PQL of 0.5 ppb as an example.