This Manual provides guidance for owners and operators of hazardous waste land disposal facilities in complying with the interim status requirements for ground-water quality monitoring in Subpart F of 40 CFR 265, (45 Fed. Reg. 33239 et seq., May 19, 1980). These regulations require owners and operators to design and implement either a detection program at facilities not known or assumed to be significantly affecting ground-water quality or an assessment program for quantifying the ground water quality effects which have occurred. Owners or operators who assumed that ground water has been affected by the facility were provided an opportunity to waive the detection program. In this case, they may enter directly into the assessment program, quantifying the extent of contamination and the rate of migration. This manual discusses the objectives of the programs, the regulatory language and the Agency's associated intent, and required monitoring systems, analyses and reporting. The guidance in this manual is applicable to EPA-administered programs. (ERA citation 09:020819)