Section 020. Classification Of Injection Wells

01. Classification of Injection Wells. For the purposes of these rules, injection wells are classified a s follows: (3-18-22) a. Class I: (3-18-22) i. Wells used by generators of hazardous waste or owners or operators of hazardous wast e management facilities to inject hazardous waste beneath the lowermost formation containing, within one-quarter (1/ 4) mile of the well bore, an underground source of drinking water. (3-18-22) ii. Other industrial and municipal disposal wells which inject fluids beneath the lowermost formatio n containing, within one-quarter (1/4) mile of the well bore, an underground source of drinking water. (3-18-22) iii. Radioactive waste disposal wells which inject fluids below the lowermost formation containing a n underground source of drinking water within one-quarter (1/4) mile of the well bore. (3-18-22) b. Class II. Wells used to inject fluids: (3-18-22) i. Which are brought to the surface in connection with natural gas storage operations, or conventiona l oil or natural gas production and may be commingled with waste waters from gas plants, dehydration stations, o r compressor stations which are an integral part of production operations, unless those waters are classified as a hazardous waste at the time of injection. (3-18-22) ii. For enhanced recovery of oil or natural gas; and (3-18-22) iii. For storage of hydrocarbons which are liquid at standard temperature and pressure. (3-18-22) c. Class III. Wells used to inject fluids for extraction of minerals including: (3-18-22) i. Mining of sulfur by the Frasch process; (3-18-22) ii. In situ production of uranium or other metals; this category includes only in-situ production fro m ore bodies which have not been conventionally mined. Solution mining of conventional mines such as stope s leaching is included in Class V. (3-18-22) iii. Solution mining of salts or potash. (3-18-22) d. Class IV: (3-18-22) i

luding: (3-18-22) i. Mining of sulfur by the Frasch process; (3-18-22) ii. In situ production of uranium or other metals; this category includes only in-situ production fro m ore bodies which have not been conventionally mined. Solution mining of conventional mines such as stope s leaching is included in Class V. (3-18-22) iii. Solution mining of salts or potash. (3-18-22) d. Class IV: (3-18-22) i. Wells used by generators of hazardous waste or of radioactive waste, by owners or operators o f hazardous waste management facilities, or by owners or operators of radioactive waste disposal sites to dispose of hazardous waste or radioactive waste into or above a formation which within one-quarter (1/4) mile of the wel l contains an underground source of drinking water. (7-1-25) ii. Wells used by generators of hazardous waste or owners or operators of hazardous wast e management facilities to dispose of hazardous waste, which cannot be classified under Subparagraphs 020.01.a.i or 020.01.d.i. of this rule (e.g., wells used to dispose of hazardous waste into or above a formation which contains a n aquifer which has been exempted pursuant to Section 025 of these rules). (7-1-25) e. Class V -- All injection wells not included in Classes I, II, III, IV, or VI. (3-18-22) f. Class VI. (3-18-22) i. Wells that are not experimental in nature that are used for geologic sequestration of carbon dioxid e beneath the lowermost formation containing a USDW; or (3-18-22) ii. Wells used for geologic sequestration of carbon dioxide that have been granted a waiver of th e injection depth requirements pursuant to requirements at 40 CFR Section 146.95; or (3-18-22) iii. Wells used for geologic sequestration of carbon dioxide that have received an expansion to the area l extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer exemption pursuant to Sectio n 025 of these rules. (3-18-22) 02. Subclassification. Class V wells are subclassified as follows: (3-18-22) a. 5A5-Electric Power Generation. (3-18-22) b

on 146.95; or (3-18-22) iii. Wells used for geologic sequestration of carbon dioxide that have received an expansion to the area l extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer exemption pursuant to Sectio n 025 of these rules. (3-18-22) 02. Subclassification. Class V wells are subclassified as follows: (3-18-22) a. 5A5-Electric Power Generation. (3-18-22) b. 5A6-Geothermal Heat. (3-18-22) c. 5A7-Heat Pump Return. (3-18-22) d. 5A8-Aquaculture Return Flow. (3-18-22) e. 5A19-Cooling Water Return. (3-18-22) f. 5B22-Saline Water Intrusion Barrier. (3-18-22) g. 5D2-Storm Runoff. (3-18-22) h. 5D3-Improved Sinkholes. (3-18-22) i. 5D4-Industrial Storm Runoff. (3-18-22) j. 5F1-Agricultural Runoff Waste1. (7-1-25) k. 5G30-Special Drainage Water. (3-18-22) l. 5N241-Radioactive Waste Disposal1. (7-1-25) m. 5R21-Aquifer Recharge. (3-18-22) n. 5S23-Subsidence Control. (3-18-22) o. 5W9-Untreated Sewage1. (7-1-25) p. 5W10- Large Capacity Cesspools2. (7-1-25) q. 5W11-Septic Systems (General). (3-18-22) r. 5W12-Waste Water Treatment Plant Effluent. (3-18-22) s. 5W20-Industrial Process Water. (3-18-22) t. 5W31-Septic Systems (Well Disposal). (3-18-22) u. 5W32-Septic System (Drainfield). (3-18-22) v. 5X13-Mine Tailings Backfill. (3-18-22) w. 5X14-Solution Mining. (3-18-22) x. 5X15-In-Situ Fossil Fuel Recovery. (3-18-22) y. 5X16-Spent Brine Return Flow. (3-18-22) z. 5X25-Experimental Technology. (3-18-22) aa. 5X26-Aquifer Remediation. (3-18-22) bb. 5X27-Other Wells. (3-18-22) cc. 5X28-Motor Vehicle Waste Disposal Wells2. (7-1-25) dd. 5X29-Abandoned Water Wells. (3-18-22) 1 The construction of wells in this subclass is currently prohibited in Idaho. 2 The construction and operation of wells in these subclasses is currently prohibited in Idaho. 021. -- 024. (RESERVED)