Basic requirements apply to all stormwater injections except roof drains. In order to meet basic requirements the owner/operator of the UIC system must submit inventory and registration information prior to construction to DEQ for review to certify that:
- No other waste or discharge is mixed with the stormwater.
Example: DEQ does not require pretreatment for roof runoff, unless it contains contaminants, such as heavy metals from plating operations, carried to the roof through exhaust vents. DEQ requires parking lot runoff to have some form of approved pretreatment.
- Stormwater runoff is minimized and no other disposal option is appropriate. If city hook ups are not available DEQ requires developers to consider the use of Low Impact Development or green options.
DEQ will verify that the site cannot use anything but a UIC system.
- No water supply wells are present within 500 feet (domestic, irrigation or industrial).
- No public drinking water supply wells are present within 500 feet or the within delineated two year time-of-travel, whichever is more protective.
- No soil or groundwater contamination is present.
Verify the site is not on the cleanup list (ECSI), leaking underground storage tanks list or Facility Profiler.
Example: Site Y once was a gas station and is now proposed as a fast food site. The gas station has not been cleaned up so the site development is denied. Or, if cleanup has occurred, the UIC systems must be located where they will not mobilize any remaining contamination.
If a site later becomes listed on ECSI and is found to be contaminated or contributing to groundwater contamination, the UIC rule authorization will be revoked.
- The injection system is not deeper than 100 feet and does not discharge into groundwater or below highest seasonal groundwater level.
Example: For bacterial protection, roof drains should have at least five feet of vertical separation between the bottom of the drywell and the high seasonal water level.
UIC systems with wet feet (in the seasonal high water table) are a high contamination risk and are to be closed upon discovery or modified to meet requirements.
- A confinement barrier or filtration medium must be present, or pretreatment might be needed to protect groundwater quality.
Not all parts of the state have soils capable of providing adequate percolation and attenuation (treatment) for stormwater disposal. Disposals at depth often circumnavigate the soils’ natural ability to treat stormwater, which is associated with the topsoil layers and the presence of organics. Some form of pretreatment is needed to minimize contaminant concentrations normally found in street/parking stormwater.
- The design and operation of the UIC system is to prevent accidental or illicit disposal, and temporary blocking of the UIC system must be available.
Example: A drywell located at a site's loading dock cannot meet this requirement. The drywell would either need to hook up to the city system or isolate the stormwater discharge from the potential spill area. Stormwater Category Requirements (these apply to Rule Authorization Requirements)
Municipal owners with 50 or more UIC systems are required to provide additional data due to the volume being discharged and the risk to groundwater quality and public health. Municipalities must submit registration inventory data 90 days prior to construction for new sites for approval. The additional data is to include:
- Evaluation of the potential impacts to groundwater quality,
- Certification that the systems are not exposed to toxics, and
- Stormwater management plan that includes:
- Stormwater systems assessment,
- Systems controls (pretreatment, BMPs and source controls),
- Injection spill prevention plan,
- Maintenance plan,
- Employee and public education, and
- Annual monitoring and record keeping.
All existing and new UIC systems must be able to meet the rule authorization requirements. If existing UIC systems do not meet all the requirements, then regardless of the number of UIC systems owned, DEQ will require a state area wide permit.
Small municipal systems with under 50 UIC systems must submit registration inventory data 90 days prior to construction at new sites, certify that the stormwater is not exposed to hazardous substances, and prepare and implement a written stormwater management plan. All existing UIC systems must be able to meet the rule authorization requirements. If the existing systems cannot meet all requirements then the city/county or state agency must apply for a permit unless the UIC systems can be closed and an alternate means of stormwater disposal, such as surface infiltration facilities, can be used.
Industrial and commercial facilities that handle hazardous substances, toxic materials and petroleum products must certify that stormwater is not exposed to hazardous substances, toxic materials and petroleum products. The certification shall include site assessment, location of the materials and stormwater discharge points, methods used to prevent exposure, sampling, site controls (pretreatment, BMPs), spill prevention for UIC systems, maintenance plan, information on past spills/releases, and prepare and implement a written stormwater management plan.
Industrial and commercial facilities with no hazardous substances must certify non-exposure every five years and prepare and implement a written stormwater management plan.
Large parking lots (big box) and high traffic areas with 1000 or more vehicle trips per day must certify non-exposure to hazardous substances, prepare and implement a written stormwater management plan, site assessment, site controls, annual monitoring and maintenance plan.
Small parking lots must certify non-exposure to hazardous materials and prepare and implement a written stormwater management plan.