UIC Well Assessment information and Timelines

Washington State Department of Ecology

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Floor drain injection well. Photo courtesy of EPA, Region 10.

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.

Who needs to complete a well assessment?

Owners of UIC wells in use prior to February 3, 2006 and used to manage stormwater must complete a well assessment.

What is the purpose of a well assessment?

The purpose of a well assessment is to determine if any UIC wells are a high threat to ground water and prepare a schedule to retrofit any high threat to ground water wells.

When do the well assessments have to be completed?

February, 2011 for owners of less then or equal to 50 existing stormwater management wells; or
February, 2013 for owners of more then 50 existing stormwater management wells.

How do we complete a well assessment?

Here is one example on how to complete a well assessment:

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. List your UIC wells within a table and ask the following for each well:
- Is the UIC well receiving a prohibited discharge? For example:
  - Untreated stormwater from a fueling area or an uncovered area that stores containers of chemicals, vehicle wash water.
  - Untreated stormwater mixed with industrial waste fluids.
  Stormwater that comes in contact with hazardous substances or wastes (see Guidance for UIC Wells that Manage Stormwater, page 5, www.ecy.wa.gov/biblio/0510067.html) would be prohibited.
- Is a UIC well receiving stormwater from an area considered a high pollutant load classification (based on the average daily traffic [ADT]), and is the vadose zone treatment capacity of the soils around and beneath the UIC well considered “none” (see Table 5.2 and 5.3, in Guidance for UIC Wells that Manage Stormwater, at www.ecy.wa.gov/biblio/0510067.htm)?
- Determine if the UIC well is consturcted into the ground water. If water is present in the well during the dry season and the well has not received any recent discharges, then the well is probably built in the ground water.
- Are the UIC wells in a ground water protection area, such as a Well Head Protection Area (WHPA), Critical Aquifer Recharge Area (CARA) or a Sole Source Aquifer (SSA)? Your local government may have additional requirements. Washington State Department of Health has an on line tool showing the WHPAs in each Washington County. Visit www.doh.wa.gov/ehp/dw/sw/default.htm. Contact your local government for information on WHPA and CARA ordinances requirements.
- If any of the questions were answered yes, you probably have a UIC well that is considered a high threat to ground water.
- Prepare and implement a schedule for retrofitting any high threat to groundwater wells. Ecology’s stormwater manuals and your local approved stormwater manual will have information on operational and structural best management practices to retrofit the high threat UIC wells. Ecology’s stormwater manuals can be found at www.ecy.wa.gov/programs/wq/stormwater/tech.html. Check with your local government for ground water protection area requirements.

What can industrial or commercial facilities use in place of a well assessment?

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 addresses stormwater discharges to UIC wells; or

For unpermitted facilities:

Prepare and implement an up-to-date stormwater pollution prevention plan that addresses discharges to 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.

What types of wells are considered a high threat to ground water in the UIC program?

UIC wells used along roads and parking areas (municipal 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.

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 groundwater table.

An example of a high threat to ground water well is a UIC well that:

Receives prohibited discharges as listed in the UIC regulation Chapter 173-218 WAC, i.e untreated stormwater from a vehicle fueling area, stormwater mixed with airport de-icing fluids (unless under a permit), stormwater from an areas where treated lumber is stored or vehicle washing; or
Receives a discharge that is determined to be an imminent public health hazard by a legal authority; or
Is built in the ground water; or
Receives 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: www.ecy.wa.gov/programs/wq/grndwtr/uic/guidance-sw.html.

What are owners required to do for UIC wells identified as a high threat to ground water?

Prepare and implement a retrofit schedule.
If a UIC well is determined to be a public health hazard action must be taken immediately. Notify Ecology and your local Department of Health agency; and
Retrofit your high-threat-to-groundwater wells.

What does "retrofit" mean?

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).

Contact your local government agency for their stormwater requirements before retrofitting your UIC wells.

The Stormwater Management Manuals for Eastern and Western Washington describe the BMPs for source control and treatment. The manuals can be found at 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.

Last updated February 2012