What is Environmental Case Closure?


Most folk responsible for cleanup of contaminated property have one thing on their mind - environmental case closure. One can’t blame them. Thoughts of money evaporating into thin air and restricted property use does that. The problem is we might not have a clear understanding of environmental case closure and what it takes to get there. WIthout that understanding, frustration and disappointment are more likely to arise when we find our expectations unmet.

Consider the frustration that might arise when you hear for the third time “just one more thing and we can look at case closure.” You thought case closure would be granted after the first two “just one more thing” requests were dealt with. What now?

Or imagine you finally got your closure letter  - saw the words “no further action” and filed it away quickly before opening a bottle of Champagne to celebrate. Picture the frustration and disappointment a year later when you have the closure letter in one hand and a letter in the other requesting more investigation because contamination was found near your property.

These examples beg the question: What is environmental case closure? In California, the target for environmental case closure is low-threat to health and the environment. Of course this can take various forms, but here we will stick to low-threat underground storage tank (UST) case closure and low-threat solvent case closure. Low-threat UST closure is specific to petroleum hydrocarbons stored in underground tanks, including gasoline, diesel, and waste oil. Low-threat solvent case closure includes most other solvents - a common example is tetrachloroethylene (PCE) released from a dry cleaner.

Road to Closure

The road to case closure has three primary milestones: investigation, cleanup, and monitoring. Investigation determines the composition, magnitude and extent of contamination. Cleanup reduces contamination and possible exposure to contamination. Monitoring shows trends over time and compliance with environmental cleanup goals. These elements are the same for UST and solvent cases. Funding solutions, regulatory policies, and cleanup goals are not the same for UST and solvent cases.

UST cases have access to funding through the UST Cleanup Fund and specific policy for UST low-threat closure. UST closure is boiled down to a checklist.

There is funding available for solvent sites through the Site Cleanup Subaccount Program (SCAP), but eligibility and long priority queues limit access. As for solvent case closure policy, it is vague at best. There is guidance for assessing closure of low-threat chlorinated solvent sites and environmental screening levels (ESLs), but no standard closure criteria like UST policy and definitely no checklist.  

Down the Road: Investigation, Cleanup, and Monitoring

WhitakerWellInstallThe road begins with an investigation, but cleanup and monitoring usually start soon after the investigation begins. The investigation process usually takes place in phases, each phase building upon the previous until the information can provide an acceptable picture of contamination in soil, soil gas, and groundwater to the oversight agency. Three sequential phases of investigation are not uncommon. Once there is enough information on the magnitude, source, and composition of contamination, cleanup starts and monitoring locations are sited.  

Cleanup that began during investigation continues until the most accessible contamination is reduced to the point where it is unreasonable to spend more money for only incremental change. Soil gas and/or groundwater monitoring that started during investigation continues through cleanup and into verification monitoring. Oftentimes, after active cleanup has ceased, natural attenuation, or the natural process of contamination reduction through mechanisms like biodegradation and chemical reaction, is relied on to reach cleanup goals. Monitoring continues until seasonal trends show acceptable declines in contamination and low-threat criteria are achieved.

How Long is the Road?

We mentioned in a previous article that, on average, the road to environmental case closure takes about 10 years to complete.  Let's check that against completing the milestones described above. In the best case scenario, investigations could be completed in one year and still account for seasonal variations. Cleanup could also be completed in a year, and if initiated during investigation, that puts the environmental case at two years.

Monitoring could also be initiated during investigation, providing about a year and a half of information by the time cleanup is complete. It’s likely another three years of monitoring would be necessary for seasonal trends to be demonstrated. That puts the case at 5 years. Now add a year for verification monitoring and site closure activities and the best scenario is 6 years to environmental case closure. If financial constraints and agency review and approval are considered, it’s easy to see environmental cases stretching to 10 years.    

End of the Road: Case Closure Letter

An environmental case closure letter marks the end of regulatory authority and oversight - the end of the road. In most cases, the closure letter is issued even though some contamination is left in place. The goal is not complete removal of all contamination, but risk reduction. Once conditions at a site are deemed low risk (low-threat) by the oversight agency, the environmental case is closed. This does not mean that you will never have to deal with your contamination problem again. Environmental case closure is conditional. 

The closure letter typically has two parts. In the first part, the letter certifies that investigation and cleanup of contamination meets all regulatory requirements for case closure, and no further action is necessary. In the second part, the letter states the conditions of closure, such as:   

  • The discovery of additional or previously unidentified contamination at the site may require additional investigation and cleanup, and
  • Soil and groundwater contamination remain at the site and could pose an unacceptable risk under certain site development activities such as site grading, excavation, or dewatering. The regulatory oversight agency, local health agency, and the appropriate local planning and building departments must be notified prior to any changes in land use, grading activities, excavation, or dewatering. This notification must include a statement that residual soil and groundwater pollution underlie the property and nearby properties. 

The first condition means that if any new contamination or contamination above levels deemed appropriate for closure are encountered, the case may be reopened. This does happen. The second condition means that any changes in property use must be declared to the regulatory oversight agency, local health agency, and the appropriate local planning and building departments. Oftentimes implementation of a soil and groundwater management plan prepared at closure is required.


In this article we described the road to environmental case closure and what case closure is. We have over 30 years of experience bringing environmental cases to closure, and we can help you. Click the link below to schedule a free consultation to see what we can do for you.