Soil Matrix Cleanup

Soil Matrix Cleanup

A Soil Matrix Cleanup, which consists of a release of 500 PPM or less, lands within the DEQs simplest level of remediation. Pending that, during the decommissioning process, no holes within the tank are observed, the DEQ will not require any additional sampling or scope of work, in addition to the usual Soil Matrix Evaluation used to close the LUST file.

Standards for a Soil Matrix Cleanup

The standard by which the DEQ closes an open file for a Soil Matrix Cleanup is as follows:

  • Removal or treatment of the contaminated soil is not required
  • An abbreviated risk assessment is allowed for the site, which is called a Soil Matrix Evaluation
  • The tank and the contaminated soil will remain within the ground
  • The final steps include creating the Soil Matrix Report and submitting the report to the DEQ. Once reviewed and approved by the DEQ, the site will be considered DEQ Certified and the site will have a “Closed Status”.
Soil Matrix Cleanup

Soil Matrix Cleanup – Tank found and marked out for sampling. The small circle inside the right side of the marked tank is the fill pipe.

Soil Matrix Cleanup

Soil Matrix Cleanup – While excavating a tank during a soil matrix decommissioning, holes are found within the tank. These holes cause diesel heating oil to leak into the surrounding soils.

Soil Matrix Cleanup

Soil Matrix Cleanup – Excavation of a tank removal soil matrix decommissioning

For more information regarding Soil Matrix Cleanup, please see the DEQ UST Cleanup Manual.

UST Soil Sampling and Tank Inspection

Soil Sampling and Tank Inspection Common Questions

A UST Soil Sampling and Tank Inspection is almost identical to a Soil Sample.  The major difference between the two is that besides sampling between 12″ to 24″ beneath the bottom of the tank, the tank itself is opened up and inspected for its contents.

Why would a Tank Inspection be needed?

There are a couple different reasons that it is required to include the additional service of the Tank Inspection to the Soil Sampling, here are a few examples of why that would be needed:

  • During a tank search an underground storage tank was found, yet the technician was unable to get the fill cap off to determine its contents.  The fill cap may be inaccessible due to the cap being covered over, rusted shut or the fill pipe itself is completely filled and the contents of the tank can not be determined.
UST Soil Sampling and Tank Inspection

UST Soil Sampling and Tank Inspection – Tank found under concrete patio, fill cap inaccessible due to patio pavers.

  • The tank had been decommissioned previously but never registered with the DEQ.  In order for the underground storage tank to be registered with the DEQ, the soil beneath the tank needs to be sampled and the contents of the tank need to be verified.

The Tank Inspection

How do you perform a Tank Inspection?

After the tank has been located and marked out for soil sampling, our technicians will dig down to the top of the tank, cut open the tank and verify the contents.

Once the tank has been opened up, what is the best case scenario?

What we always hope for is clean soil samples and a properly decommissioned tank.  With samples below the DEQ reporting level of 50 PPM and a tank filled with clean material, the UST can then be registered with the DEQ.

UST Soil Sampling and Tank Inspection

UST Soil Sampling and Tank Inspection – Properly decommissioned tank filled with a concrete slurry.

What if the tank has been decommissioned with a proper fill material, but not filled all the way to the top of the tank, and the soil samples come back below the DEQ reporting level?

As long as the samples come in below the DEQ reporting level of 50 PPM, the remaining gap can be filled with additional fill material to ensure the tank has been decommissioned properly.  Once the tank has been certified as decommissioned, it can now be registered with the DEQ.

UST Soil Sampling and Tank Inspection

UST Soil Sampling and Tank Inspection – Tank inspection with gap in the proper fill material, tank will be filled with additional fill material and can then be registered with the DEQ

 

What are additional circumstances that are encountered with Tank Inspections?

Fill Material

  • Gap in proper fill material, below reporting level of 50 PPM:  Fill void with additional fill material and the tank can then be registered with the DEQ.
  • Proper fill material, leaking tank above 50 PPM: Tank has been decommissioned properly, remediation is required to determine that the leak has been contained. Once the clean-up is completed, the tank can then be registered with the DEQ.
  • Improper fill material: Improper fill material needs to be removed and the tank re-decommissioned. Additionally, if the tank is leaking above 50 PPM, remediation will need to take place to clean-up the site. Once the new decommissioning is completed, the tank can then be registered with the DEQ.

Water

  • Water in gap of the proper fill material, below reporting level of 50 PPM: Pump water out of the void and fill gap with additional fill material. Tank can now be registered with the DEQ.
  • Water completely fills the tank: Regardless of the fill material, everything within the tank needs to be pumped out and replaced with new fill material. Additionally, if the tank is leaking above 50 PPM, remediation will need to take place to clean-up the site. Once the new decommissioning is completed, the tank can then be registered with the DEQ.
UST Soil Sampling and Tank Inspection

UST Soil Sampling and Tank Inspection – Liquid found inside of opened tank

  • Tank is opened and it is empty.  If the samples come in below 50 PPM, the tank can be decommissioned and registered with the DEQ.  If the samples come in above 50 PPM, the tank can be decommissioned with remediation and then registered with DEQ
UST Soil Sampling and Tank Inspection

UST Soil Sampling and Tank Inspection – Empty tank discovered during a Tank Inspection.