Regulations on federal and state underground injection systems are complex due to the variety of injection system designs, types, proposed uses, variation in the local site geology. Any owner or operator of any type of Class V system is required by federal and/or state regulations to:
- Register with DEQ and provide requested data;
- Obtain written DEQ approval to operate under authorization by rule or a state permit.
- Properly close any the system requiring closure and obtain written approval from DEQ.
- Prevent movement of any injection fluid into a public or private water supply that might cause endangerment (prohibition of contaminant migration to groundwater). This applies to injection system construction, operation, maintenance, conversion, plugging, abandonment, or any other activity.
- Comply with other federal regulations (40 CFR part 144-146).
- Comply with any other measures required by DEQ in OAR 340-044. State rules prohibit the use of injection systems where better treatment or protection is available, for example, when a stormwater or municipal sewer is available).
For example, City X discharges road runoff to dry wells which are 20 feet deep. The local high groundwater table is 15 feet. This injection system is in violation of federal endangerment and state regulations because it is discharging below the high groundwater table using the uppermost aquifer as mixing zone for untreated discharges. The construction and operation of such a drywell with wet feet endangers all local groundwater users, both private and public.
Prohibited injection systems
The following types of injection are not allowed in Oregon:
- Class I injection of hazardous or radioactive waste or other fluids beneath the lowermost formation containing a source of drinking water.
- Class II injection used for liquid hydrocarbon storage
- Class III injection associated with fluids for mineral or natural resource extraction
- Class IV injection of hazardous or radioactive waste into or above a formation containing a source of drinking water, except for remediation activities with prior approval and oversight by EPA or DEQ.
- Class V injection:
- An injection system receiving motor vehicle waste from repair or maintenance activities (5X28)
- Fluids from floor pits or floor drains at industrial or commercial facilities including subsurface fluid distribution systems (5x28)
- Fluids from industrial or commercial areas where hazardous substances, toxic materials or petroleum products are stored, used or handled (see exception under 340--044-0015 (2)(c)
- Industrial process or municipal wastewater discharged directly into an underground source of drinking water
- Industrial, municipal or other disposal into a water bearing zone or upper most aquifer (the injection system is then defined a well under the Department of Water Resources rules and must be constructed as such, and cannot be used for disposal).
- New cesspools of any capacity cannot be permitted due to health concerns.
- Existing cesspools serving 20 or more people or 2,500 gpd after April 5, 2005 (5W10)
- New drill holes used for sanitary waste, sewage or industrial/commercial waste (see exceptions under 340-044-0015 (3)(b), 340-044-0017 and 0018 (3)). (5W9)
- Agricultural drainage (5F1), prohibited in Oregon, due to their high risk potential for contamination of groundwater.
All existing and new injection systems (Class I through Class V) are required to be inventoried and the data submitted to DEQ under OAR 340-044-0018. This is considered to be inventory registration. New injection systems are to be registered and approved by DEQ in writing prior to construction or use. For example:
- All Class II systems must be inventoried and the data registered with DEQ, meet DEQ siting requirements and acquire an individual Water Pollution Control Facility (WPCF) permit.
- All injection systems operating under a WPCF permit must also be inventoried and the data registered as a UIC with DEQ, including onsite wastewater treatment systems.
- Privately owned residential driveway and garage drains need to be registered and approved by DEQ as Class V systems.