On January 18, 1991, EPA proposed to amend title 40 of the Code of Federal Regulations (CFR) section 265.91 to allow alternate placement of hydraulically downgradient monitoring wells at interim status facilities where existing physical obstacles prevent installations at the limit of the waste management area.

With this December 23, 1991 final rule, EPA promulgated a final rule implementing amendments to 40 CFR sections 260.10 and 265.91. This rule is necessary to allow facilities to install alternate ground-water monitoring wells in certain circumstances where they are unable to avoid existing physical obstacles. This rule provides that the owner or operator of an existing facility may demonstrate that an alternate hydraulically downgradient monitoring well location will meet several criteria. This demonstration must be certified by a qualified ground-water scientist. This rule also promulgates a definition of "qualified ground-water scientist."

• Hazardous Waste Management System: Amendments to Interim Status Standards for Downgradient Ground-Water Monitoring Well Locations at Hazardous Waste Facilities - Federal Register Notice, December 23, 1991 (PDF)(2 pp, 7 K, December 23, 1991, FR Vol. 56, No. 246)