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Indiana Department of Environmental Management

IDEM > Compliance > Land Compliance > Underground Storage Tanks (USTs) > UST Closure Assessment UST Closure Assessment


An environmental site assessment of soil and ground water is required for all regulated UST system closures and must be included into the UST System Closure Report. The report must be submitted to IDEM within 30 days after UST system closure completion. Since the UST Change Rule is final on September 29, 2004, there are new site assessment requirements. This document is designed to assist you in complying with the new requirements found in 329 IAC 9-6-2.5. In addition, the site assessment must be consistent with the Remediation Closure Guide and the Remediation Program Guide. The following is a summary of the requirements:

Closure Types

There are three types of UST System Closures.

  • Removal - A "removal" closure is when all USTs, piping and dispensers are physically removed.
  • In-place - An "in-place" closure is when a portion or all of the USTs, piping, and dispensers are closed without removal. In-place closures require prior approval from IDEM. The conditions for obtaining approval include, but are not limited to, all or a portion is inaccessible due to buildings or structures.
  • Change-in-service - A "change-in-service" closure is when a UST system is converted from being used to store regulated substances to unregulated substances. Change-in-service closures require prior approval from IDEM.

Soil Sampling

Soil samples should always be collected from the area most likely to be contaminated based on visual observations, odor and field screening, e.g. photoionization detector (PID), flame ionization detector (FID) or gas chromatograph. Bottom samples are always required. Samples must be collected from native soil except for excavated material. Composite samples are not acceptable.

  • Removal
    • Bottom samples
      • USTs ≤10,000 gallons - two (2) within two (2) feet below both ends of the each UST
      • USTs >10,000 gallons, one (1) additional within two (2) feet below the middle of the UST
    • Sidewall samples
      • UST pit perimeter <80 feet - four (4) sidewall samples taken at a point half the distance from the surface to the bottom of the UST excavation
      • UST pit perimeter ≥80 feet - one sidewall sample for every 20 linear feet from halfway between the surface to the bottom of the UST excavation
    • Piping samples
      • Pipe run ≤20 feet - one (1) sample half way between UST and dispenser or fill port
      • Pipe run ≥20 feet - one (1) sample for every 20 linear feet of pipe run
      • One sample under every piping elbow or connector
    • Dispenser samples - One sample under each dispenser
    • Excavated Material - Sampling of excavated material must occur for every 50 cubic yards of material that is treated, disposed, or returned to the excavation area as backfill.
  • In-place and change-in-service - If the exact location of the UST and piping is not known, the borings should be installed as close as practicable.
    • Borings
      • One (1) continuously sampled boring within three (3) feet of the UST and every 20 linear feet around the UST, with a minimum of four (4) borings and extended at least two (2) feet below the bottom of the UST
      • Borings ≤15 feet - A minimum of two (2) samples taken from
        • A point where contamination is detected and at the bottom of the boring, or
        • At the midpoint and bottom of the boring
      • Borings >15 feet - Three (3) samples at ≥1 foot below ground surface, where release is suspected and/or detected
    • Piping samples - Borings within three (3) feet of and two (2) feet below pipe run, elbow or connector
      • Soil under piping must be samples every 20 linear feet or fraction thereafter, along the piping run
      • Pipe run <20 feet - one (1) sample half way between UST and dispenser or fill port
      • One sample under every piping elbow or connector
    • Dispenser samples - One boring within three (3) feet of and two (2) feet below each dispenser

Ground Water Sampling

  • Removal
    • Excavation - A minimum of one (1) ground water sample from each excavation where groundwater is encountered
    • Borings - A boring must be installed within any area where a release is suspected or substantiated by visual observations, odors, or field screening; a water sample must be collected within the first saturated zone or at a total depth of 30 feet below grade at the area of suspected or confirmed release. If ground water is not encountered within a depth of 30 feet below grade, a soil sample must be collected at the base of the boring.
  • In-place or change-in-service
    • Borings - Four (4) borings must be installed in each of the principal directions within ten (10) feet of the area most likely to have contaminated groundwater. The aforementioned groundwater sampling boring procedures for removal must also be followed when sampling for in-place or change-in-service closures.

Sample Analyses

Table 3.1 in the Remediation Program Guide lists potential petroleum contaminants for various product or waste types and media. For source types not listed in the table, call the IDEM Leaking Underground Storage Tank Section at (317) 232-8900 or toll free at (800) 451-6027 ext. 2-8900

Release Reporting

If at any time, during the closure process, you suspect or confirm a release, you must report the release to IDEM within 24 hours:

During normal business hours:

  • Phone: (317) 232-8900
  • Toll-free: (800) 451-6027 ext 28900
  • Fax: (317) 234-0428
  • Email: LeakingUST at

After hours, holidays and weekends:

  • Phone: (317) 233-7745
  • Toll-free: (888) 233-7745

Soil Sampling for VOCs

All soil sampling should be consistent with the guidance found in Soil Sampling Techniques for VOCs.

UST Change Rule

The complete rule will be published in the Indiana Register on October 1 and will be available on the Web on or after that date. Meanwhile, the change rule package is available.

IDEM QA/QC Elements

All procedures, methods and documentation should meet the requirements specified in Section 3.9.1 of the Remediation Closure Guide (and summarized in Table 3-A).

Questions or Comments

Call the LUST program at (317) 232-8900 or e-mail at "LeakingUST at" regarding this document. All other questions related to UST Closure notification and reporting should be directed to the UST Program at (317) 234-6645.