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UIC Well Assessment
Information and Timelines
Reminder: All UIC wells have to be registered with Ecology except for
UIC wells located on Tribal land. Wells located on tribal land need to be
registered with the Environmental Protection Agency. UIC wells only need to
be registered once. (see registration webpage for registration time lines at
www.ecy.wa.gov/programs/wq/grndwtr/uic/registration/reg_info.html.
Owners of UIC wells used to manage stormwater that were built and in use prior to February 3, 2006 need to complete a well assessment.
The purpose of a well assessment is to determine if any UIC wells are a high threat to ground water by evaluating the potential risks to ground water from using the well.
A UIC well is considered a high threat to ground water when it receives fluids that cannot meet the Water Quality Standards for Ground Waters of Washington Chapter 173-200 WAC (GWQS) criteria at the top of the ground water table.
UIC wells used along roads and parking areas (municipally and non-municipal ownership) are not considered a high threat to ground water if they meet the requirements of the Guidance for UIC Wells that Manage Stormwater.
An example of a high threat to ground water well is a UIC well that receives drainage from the following areas and the fluids have not been pretreated:
- When storm water comes into contact with a vehicle fueling area, airport de-icing activities, storage of treated lumber or vehicle washing; or
- A UIC well that receives a discharge that is determined to be an imminent public health hazard by a legal authority; or
- A UIC well that receives prohibited discharges as listed in the UIC regulation Chapter 173-218 WAC; or
- UIC wells built in the ground water; or
- A UIC well receiving a high pollutant load where the vadose zone between the bottom of the UIC well and the top of the ground water has no treatment capacity, or the vadose zone conditions are unknown according to Tables 5.2-5.4 of the Guidance for UIC Wells that Manage Stormwater: http://www.ecy.wa.gov/programs/wq/grndwtr/uic/guidance-sw.html.
- Prepare and implement a retrofit schedule.
- If a UIC well is determined to be a public health hazard action must be immediately taken. Notify Ecology and your local Department of Health agency.
Retrofit means to take actions to reduce the pollutant load from a UIC well to meet the regulatory requirements. These actions may include, but are not limited to:
- Changes to the source control best management practices (BMPs) around the well. Source control BMPs are structures or operations that help prevent pollutants from mixing with stormwater; or
- Changes to the treatment BMPs. Upgrade to the UIC well such as adding a catch basin insert, spill control device; and/or addition of other treatment facilities; or
- Decommissioning (closure).
The Stormwater Management Manuals for Eastern and Western Washington describe the BMPs for source control and treatment. The manuals can be found at http://www.ecy.wa.gov/programs/wq/stormwater/tech.html.
UIC well closure requirements are described in 173-218-120, and can be found at 173-218-120.
- Gather the following information and complete each step:
- Review the land use around the UIC well that drains to the well. Land use affects the quality of the discharge going to the well. For example, stormwater that runs off a fueling area can pick up the fuel, oil or grease or sediment; or in an uncovered area that stores containers of chemicals.
- Determine if the UIC well is built into the ground water. During the dry season, if the well has not received any recent discharges and water is in the well, then the well is probably built in the ground water.
- From the information gathered from the previous bullets, are any of your UIC wells determined to be a high threat to ground water (see next section)?
- Prepare and implement a schedule for retrofitting any high threat to ground water wells.
If an industrial facility has or will have a wastewater discharge permit issued pursuant to Chapter 90.48 RCW, including a National Pollutant Discharge Elimination System (NPDES) permit, the associated storm water pollution prevention plan may be used in place of the well assessment, provided the storm water pollution prevention plan specifically addresses storm water discharges to UIC wells; or
For unpermitted facilities:
- The preparation and implementation of a storm water pollution prevention plan can be used in place of the well assessment if applied to the UIC wells; or
- Provide documentation that the well does not pose a threat to ground water. Examples of documentation include, but are not limited to:
- a site drainage map for the UIC wells that describes the activities that occur in the areas that drain to the UIC wells that could affect the stormwater quality, or
- A no-exposure certification form completed for discharges to ground.
Contact us for more information
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