Regulated Storage Tank Cleanup and Closure

When a UST is out of use, it means the tank has been emptied so that no more than one inch of product remains, or that no more than 0.3 percent by weight of the total capacity remains. USTs that are out of use continue to be assessed registration fees until the tanks are removed or permanently closed. For information regarding out of use UST compliance requirements, visit the department's Underground Storage Tank Requirements webpage.

Site Assessment

Once a tank is taken out of use, a site assessment must be conducted within 12 months, according to Section 5 of the Missouri Risk-Based Corrective Action (MRBCA) Process for Petroleum Storage Tanks guidance, or another process approved by the department. A site assessment must include soil and groundwater sampling in the areas where a release would have most likely occurred. Soil borings should be advanced on each side of the USTs, piping and pump islands/ dispensers. These sampling points should be advanced so that groundwater samples can be collected, if groundwater is encountered. 

Permanent Closure

Tanks that remain out of use must be permanently closed within five years of being taken out of use (not associated with the date of the assessment). Closure means to permanently remove the UST, including piping, from the ground or close it in place. Both methods require the owner or operator to notify the department prior to closure. The closure must also be completed according to Section 4 of the Missouri Risk-Based Corrective Action (MRBCA) Process for Petroleum Storage Tanks guidance, or another process approved by the department. The procedures involved with the closure process include:

• Filing a Closure Notice for Underground Storage Tanks MO 780-2121 form with the department at least 30 days before closure activities. The department should approve the Closure Notice before closure activities can begin.
• Notify the department at least three days before closure activities begin at the site.
• Notify the department immediately if a spill or leak is encountered. All reports must be made to the department's Environmental Services Program Emergency Spill Line at 573-634-2436.
• Make sure tank and materials are properly disposed according to applicable regulations.
• Submit a final Closure Report and associated documentation.
  • Closure Report for Petroleum Releases at Underground Storage Tank Sites MO 780-2120
  • Tank Closure Checklist - PUB2218
  • Statement of Closure Deed Notice for an In-place Closure of Underground Storage Tanks

Sample data collected for the site assessment may be used for the closure report only if:

• The tank has not contained any regulated substances since the data was collected
• No new or additional signs of a release have been reported or found
• A written request to use the data as part of a closure plan has been approved by the department
• Additional soil samples underneath the tanks are taken during tank removal

Environmental Consultants

This list is not comprehensive. It lists consultants and laboratories from which the department has received reports. The information is as it appeared when last provided to the department, so it may no longer be accurate. This list does not constitute an endorsement or recommendation of any individual person, company or laboratory. Additional consultants and laboratories are available in phone directories and other resources.

• Consultant Address Book

Missouri has reported over 4,900 releases from USTs in the past 10 years. Releases from USTs can cause fires or explosions that threaten human safety. Releases can also contaminate groundwater that many citizens depend on for their water supply. The department provides technical oversight for site characterizations and putting cleanup actions in place at regulated leaking underground storage tank sites in Missouri. This includes reviewing and approving site investigation reports, corrective action plans and quarterly monitoring reports.

Some basic investigative and remediation technologies commonly accepted by the department include the following:

• Pushprobe Technologies
• Expedited or Accelerated Site Assessments
• Oxygen Release Compound
• Monitoring Natural Attenuation
• Landfarming/Landfilling
• SVE/Air Sparging and Dual Phase Treatment
• Ex-situ Bioremediation
• Vacuum Enhanced Recovery Systems (VERS)

When managed properly, petroleum-contaminated soil (PCS) may be used in many construction applications as a direct replacement or substitute for other fill materials. For more information, please review the department's Beneficial Use of Petroleum Contaminated Soil - PUB2177 fact sheet.

The Missouri Risk-Based Corrective Action (MRBCA) Process for Petroleum Storage Tanks describes the process the department uses to manage petroleum releases at petroleum storage tank sites. For more information, visit the department's Tanks Risk-Based Corrective Action webpage.

The U.S. Environmental Protection Agency (EPA) requires each state that receives funding under Subtitle I to provide annual public record information for the state that must include:

• The number, sources and causes of underground storage tank releases in the state
• The record of compliance by underground storage tanks in the state with Subtitle I or a state program approved under Section 9004 of Subtitle I
• Data on the number of underground storage tank equipment failures in the state

Listed below are the Source and Cause reports for the past two years. For copies of older reports, dating back to 2008, please contact the department's Underground Storage Tanks Section.

• Source and Cause Report, FFY 2023
• Source and Cause Report, FFY 2022