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Feasibility Evaluation of the Arkansas Valley Pipeline Water Works! Committee June 2003 Classes of Injection Wells The EPA groups underground injection into five classes for regulatory control purposes. Each class groups wells with similar functions and construction and operating features so that technical requirements can be applied consistently to the class. Class I includes the emplacement of hazardous and non-hazardous fluids (industrial and municipal wastes) into isolated formations beneath the lowermost USDW. Because they may inject hazardous waste, Class I wells are the most strictly regulated and are further regulated under the Resource, Conservation and Recovery Act (RCRA). Class II includes injection of brines and other fluids associated with oil and gas production; Class III encompasses injection of fluids associated with solution mining of minerals; Class IV .addresses injection of hazardous or radioactive wastes into or above a USDW and is banned unless authorized under other Statutes for groundwater remediation. Class V includes all underground injection not included in Classes I-IV. Class V wells inject non-hazardous fluids into or above a USDW and are typically shallow, on-site disposal systems, such as floor and sink drains which discharge directly or indirectly to ground water, dry wells, leach fields, and similar types of drainage wells. Further information on EPA's UIC program can be found on EPA's UIC website (http://www.epa.Gov/safewater/uic/rep&guid.html). Specific Regulations for Class I Wells EPA considers a well used for injection of RO reject wastewater as a Class I injection well. Class I injection wells are regulated under Subpart B of 40 CFR, Chapter 1, Section 146. In general, the regulations state that Class I wells shall be sited so that they inject into a formation which is beneath the lower-most formation containing, within 0.25 mile of the well bore, an underground source of drinking water. Class I wells shall be cased and cemented to prevent movement of fluids into or between underground sources of drinking water, and (unless injecting non-corrosive municipal waste) shall inject fluids through tubing with a packer set immediately above the injection zone, or tubing with an approved fluid seal as an alternative. The tubing, packer and fluid seal shall be designed for the expected service. In addition, appropriate logs and other tests shall be conducted during the drilling and construction of Class I wells and an accompanying report must be submitted. Also, at a minimum, the fluid pressure, temperature and fracture pressure of the injection formation, as well as other physical and chemical characteristics of the injection matrix and formation fluids, must be determined. Minimum operating requirements state that pressure at the wellhead shall not exceed a maximum calculated to assure that pressure in the injection zone does not initiate new fractures or propagate existing fractures, and that injection does not cause movement of injection or formation fluids into an USDW. 41 GEI Consultants, 1nC. 01284 03-06-30 Feasibility Evaluation Final