How the cleanup process works

Cleanup sites are construction projects that remove harmful contamination from our environment and put properties back into use. Sites can be as small as a gas station spill, or as large and complex as the Tacoma Smelter Plume that impacts thousands of acres.

How many cleanup sites does Washington have?

There are about 12,900 cleanup sites on land and in water, with half needing "no further action." But this list keeps growing with about 300 new sites discovered each year. The Model Toxics Control Act (MTCA) drives the process to clean them up.

What are the steps in the MTCA cleanup process?

  1. Discovery & Initial Investigation. Find a hazardous spill or suspect one happened in the past?Report it to Ecology and we’ll investigate. Owners may clean it up at this stage. If not, we'll add it to our Confirmed & Suspected Contaminated Sites List.
  2. Hazard Assessment. We'll rank the site’s hazard by comparing it to known sites. If it’s a threat, it goes on our Hazardous Sites List.
  3. Remedial Investigation & Feasibility Study. Scientific studies show us how far contamination traveled and help us develop cleanup options.
  4. Cleanup action plan. We’ll collaborate to develop a plan that specifies standards, methods, and schedules.
  5. Cleanup. We’ll work with the responsible people to clean up and remove sources of pollution.
  6. Extra steps and legal actions. We’ll take steps to make sure cleanups protect your health and the environment.
  7. De-listing. We'll remove the site from the Hazardous Sites List after it meets cleanup standards and requirements.

Find more details about these steps in the table below.

What are cleanups and why do they matter?

Cleanups are construction projects that protect our health and environment and put abandoned properties back into use. Cleanups (also called remedial actions) can happen on land or in water. They remove or isolate harmful substances such as petroleum and arsenic so our residents, wildlife, and economy can thrive.

What is the Model Toxics Control Act?

The Model Toxics Control Act (MTCA) is Washington’s principal environmental law that guides cleanups. Our Toxics Cleanup Program uses steps in MTCA to conduct formal cleanups. Property owners who conduct independent cleanups might not follow all these steps but still must meet MTCA's cleanup standards.

What’s the difference between “formal” and “independent” cleanups?

  • Ecology conducts or supervises formal cleanups when property owners are under court order or decree, or when cleanups are funded by legislative initiatives. Formal cleanups meet MTCA standards. You can provide input during public meetings and comment periods.
  • Property owners can conduct independent cleanups on their own or with help from our Voluntary Cleanup Program (VCP). Independent cleanups still meet MTCA standards, but owners set their own timelines. They can ask for our help through the VCP but don't have to. They only need to hold public meetings or comment periods if a site is being removed from the Hazardous Sites List.
  • Find more cleanup options.

What are MTCA's formal cleanup steps, rules, and policies?


Rules & policies

Discover a site? Report it and we'll investigate.  
Notice a leak from an underground storage tank? Report it to Ecology within 24 hours. Find another type of hazardous spill? Report it to Ecology within 90 days. We’ll conduct an initial investigation and follow up with tank or property owners. Simple sites may get cleaned up at this stage. Complex sites take longer. We’ll send early notice letters to owners and collaborate to solve the problem.

WAC 173-340-300-450(5)

WAC 173-360-360-372 & -375

WAC 173-340-310

Policy 300: Site Discovery & Reporting

Policy 310A: Initial Investigations
Conduct a Site Hazard Assessment (SHA).  

When we can't rule out contamination or ensure it gets cleaned up during the initial investigation, we (or local health department partners) will conduct a SHA. This evaluates the potential risk to human health and the environment. We'll assign a hazard ranking score using the Washington Ranking Method and add the site to our Hazardous Sites List.

WAC 173-340-320

WAC 173-340-330

Policy 330A: Listing of sites on the Hazardous Sites List

Procedure 320: Site Hazard Assessment and ranking of MTCA sites by Ecology staff

Procedure 321: Site Hazard Assessment of MTCA sites by local health districts/departments for ranking under Washington Ranking Method

Collect data for Remedial Investigation & Feasibility Study (RI/FS).
We collect and analyze environmental data to learn how far contamination has traveled and potential impacts to human health and the environment. Next, we identify and select options in RI/FS reports. A State Environmental Policy Act (SEPA) review may also be required. Watch for opportunities to comment on drafts in the Site Register and Public Input & Events Listing. WAC 173-340-350, and -355 through -370
Develop the Cleanup Action Plan.  

Using public comments and RI/FS data, we work with many people and agencies to develop the plan. This specifies cleanup methods, standards, and schedules. It also describes any monitoring needed during and after the cleanup. Find opportunities in our Site Register and Public Input & Events Listing to comment and attend public meetings.

WAC 173-340-380
Clean up the site!  

Cleanups are construction projects that remove or isolate hazardous waste from our environment. Engineering Design Reports define these activities, such as how we’ll remove a leaking underground storage tank.

Cleanups can be dirty, costly, and take years to complete but they’re transforming our environment like Port Gamble Bay. There, we're using barge-mounted cranes to dredge contaminated sediment and remove tons of creosote-soaked debris. Shellfish and wildlife are returning to the shoreline where a lumber mill once stood.

WAC 173-340-400 and -410
Take extra steps that protect human health and environment.  

We may:

  • Refer cleanup emergencies to Ecology’s Spills Program for immediate action.
  • Take interim remedial actions to reduce risk to human health and environment, and partially clean up contamination.
  • Use environmental covenants (also called institutional controls) that prohibit certain activities that could expose people to hazardous waste remaining at a site, or impact a cleanup’s integrity over time.
  • Conduct monitoring, Five-Year Periodic Reviews, and ongoing operations & maintenance to ensure cleanups meet MTCA standards and protect your health.

WAC 173-340-430

WAC 173-340-440 (1)

WAC 173-340-400 (6c) and -440 (11)

WAC 173-340-410

WAC 173-340-420

Review legal documents available for comment for formal cleanups.  

We may issue an:

  • Agreed Order to formalize an agreement between Washington state and potentially liable persons (PLPs) for actions needed at the site.
  • Enforcement Order, requiring cleanup. Failure to comply may result in penalties and substantial liability for costs.

WAC 173-340-530

WAC 173-340-540

Policy 530A: Agreed orders

Policy 540A: Enforcement orders

Courts of law may approve and issue a:

  • Consent Decree to formalize an agreement between Washington state and PLPs about actions needed at the site.
  • De Minimis Consent Decree stating that the amount of contamination contributed by one or more PLPs is insignificant in amount or toxicity.
  • Prospective Purchaser Consent Decree indicating that a person wants to purchase, redevelop, or reuse the site, is not currently liable for cleanup at a site.

WAC 173-340-520

RCW 70.105D.040 (4a)

Policy 520A: Consent decrees

Policy 520C: De minimis consent decrees

RCW 70.105D.040 (5)
WAC 173-340-520 (1c)

Policy 520B: Prospective purchaser agreements

De-list the site.  

We’ll remove a site from the Hazardous Sites List after it meets all cleanup standards and requirements. Watch for opportunities to comment in the Site Register and Public Input & Events Listing.

WAC 173-340-330 (7)

Policy 330B: Removal of sites from Hazardous Sites List