
The following list is for informational purposes only and does not mean the well types are allowed in Washington. Class V wells are allowed in Washington if they can meet the requirements of Chapter 173-218 WAC (Underground Injection Control Program) and Chapter 173-200 WAC (Water Quality Standards for Ground Waters of the State of Washington).
Visit www.epa.gov/safewater/uic/class5/index.html for additional information on the different Class V wells used in the United States.
| WELL CODE | DRAINAGE WELLS (aka DRY WELLS) |
| 5F1 | Agricultural Drainage Wells – receive irrigation tailwaters, other field drainage, animal yard, feedlot, or dairy runoff, etc. |
| 5D2 | Storm Water Drainage Wells – receive storm water runoff from paved areas, including parking lots, streets, residential subdivisions, building roofs, highways, etc. |
| 5D3 | Improved Sinkholes – receive storm water runoff from developments located in karst topographic areas. |
| 5D4 | Industrial Drainage Wells – include wells located in industrial areas which primarily receive storm water runoff but are susceptible to spills, leaks, or other chemical discharges. |
| 5G30 | Special Drainage Wells – are used for disposing water from sources other than direct precipitation. Examples of this well type include: landslide control drainage wells, potable water tank overflow drainage wells, swimming pool drainage wells, and lake level control drainage wells. |
| WELL CODE | GEOTHERMAL RE-INJECTION WELLS |
| 5A5 | Electric Power Re-injection Wells – re-inject geothermal fluids used to generate electric power -– deep wells. |
| 5A6 | Direct Heat Re-injection Wells – re-inject geothermal fluids used to provide heat for large buildings or developments – deep wells. |
| 5A7 | Heat Pump/Air Conditioning Return Flow Wells – re-inject ground water used to heat or cool a building in a heat pump system – shallow wells. |
| 5A8 | Groundwater Aquaculture Return Flow Wells – re-inject ground water or geothermal fluids used to support aquaculture. Non-geothermal aquaculture disposal wells are also included in this category (e.g. Marine aquariums in Hawaii use relatively cool sea water). |
| WELL CODE | DOMESTIC WASTEWATER DISPOSAL WELLS |
| 5W9 | Untreated Sewage Waste Disposal Wells – receive raw sewage wastes from pumping trucks or other vehicles which collect such wastes from single or multiple sources. (No treatment) |
| 5W10 | Cesspools – include multiple dwelling, community or regional cesspools, or other devices that receive wastes and which must have an open bottom and sometimes have perforated sides. Must serve greater than 20 persons per day if receiving solely sanitary wastes. (Settling of solids) |
| 5W11 | Septic Systems (Undifferentiated disposal method) – are used to inject the waste or effluent from a multiple dwelling, business establishment, community, or regional business establishment septic tank. Must serve greater than 20 persons per day if receiving solely sanitary wastes. (Primary Treatment) |
| 5W31 | Septic Systems (Well Disposal Method) – are used to inject the waste or effluent from a multiple dwelling, business establishment, community, or regional business establishment septic tank. Examples of wells include actual wells, seepage pits, cavitettes, etc. The largest surface dimension is less than or equal to the depth dimension. Must serve greater than 20 persons per day if receiving solely sanitary wastes. (Less treatment per square area than 5W32) |
| 5W32 | Septic Systems (Drainfield Disposal Method) – are used to inject the waste or effluent from a multiple dwelling, business establishment, community, or regional business establishment septic tank. Examples of drainfields include drain or tile lines, and trenches. Must serve more than 20 persons per day if receiving solely sanitary wastes. (More treatment per square area than 5W31) car washes, laundromat, steam cleaners. |
| 5W12 | Domestic Wastewater Treatment Plant Effluent Disposal Wells – dispose of treated sewage or domestic effluent from facilities ranging from small package plants up to large municipal treatment plants. (Secondary or further treatment) |
| WELL CODE | MINERAL AND FOSSIL FUEL RECOVERY RELATED WELLS |
| 5X13 | Mining, Sand, or Other Backfill Wells – are used to inject a mixture of fluid and sand, mill tailings, and other solids into mined out portions of subsurface mines whether what is injected is a radioactive waste or not. Also includes special wells used to control mine fires and acid mine drainage wells. |
| 5X14 | Solution Mining Wells – are used for in-situ solution mining in conventional mines, such as stopes leaching. |
| 5X15 | In-Situ Fossil Fuel Recovery Wells – are used for in-situ recovery of coal, lignite, oil shale, and tar sands. |
| 5X16 | Spent-Brine Return Flow Wells – are used to re-inject spent brine into the same formation from which it was withdrawn after extraction of halogens or their salts. |
| WELL CODE | OIL FIELD PRODUCTION WASTE DISPOSAL WELLS |
| 5X17 | Air Scrubber Waste Disposal Wells – inject wastes from air scrubbers used to remove sulfur from crude oil which is burned in steam generation for thermal oil recovery projects. (If injection is enhanced recovery and not disposal, it is a Class II well.) |
| 5X18 | Water Softener Regeneration Brine Disposal Wells – inject regeneration wastes from water softeners which are used to improve the quality of brines used for enhanced recovery. (If injection is enhanced recovery and not disposal, it is a Class I well.) |
| WELL CODE | INDUSTRIAL/COMMERCIAL/UTILITY DISPOSAL WELLS |
| 5A19 | Cooling Water Return Flow Wells – are used to inject water which was used in a cooling process, both open and closed loop processes. |
| 5W20 | Industrial Process Water and Waste Disposal Wells – are used to dispose of a wide variety of wastes and wastewaters from industrial, commercial, or utility processes. Industries include refineries, chemical plants, smelters, pharmaceutical plants, laundromats and dry cleaners, tanneries, laboratories, petroleum storage facilities, electric power generation plants, car washes, electroplating industries, etc. |
| 5X28 | Automobile Service Station Disposal Wells – inject wastes from repair bay drains at service stations, garages, car dealerships, etc. |
| WELL CODE | RECHARGE WELLS |
| 5R21 | Aquifer Recharge Wells – are used to recharge depleted aquifers and may inject fluids from a variety of sources such as lakes, streams, domestic wastewater treatment plants, other aquifers, etc. |
| 5B22 | Saline Water Intrusion Barrier Wells – are used to inject water into fresh water aquifers to prevent intrusion of salt water into fresh water aquifers. |
| 5S23 | Subsidence Control Wells – are used to inject fluids into a non-oil or gas producing zone to reduce or eliminate subsidence associated with overdraft of fresh water and not used for the purpose of oil natural gas production. |
| WELL CODE | MISCELLANEOUS WELLS |
| 5N24 | Radioactive Waste Disposal Wells – include all radioactive waste disposal wells other than Class IV wells. |
| 5X25 | Experimental Technology wells – include wells used in experimental or unproven technologies such as pilot scale in-situ solution mining wells in previously unmined areas. |
| 5X26 | Aquifer Remediation Related Wells – include wells used in experimental or unproven technologies such as pilot scale in-situ solution mining wells in previously unmined areas. |
| 5X27 | Other Wells – include any other unspecified Class V wells. |
| 5X29 | Abandoned Drinking Water Wells – include those which are used for disposal of waste. |
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