Practical Environmental Solutions, P.C.Practical Environmental Solutions, P.C.
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Contamination Cleanup

Although underground oil tanks are not required to be removed, State and Federal laws require petroleum contamination cleanup.  Because 88% of underground oil tanks have leaked, most buried oil tanks will require a soil cleanup and a groundwater assessment. 

Heating oil contamination tends to remain localized at the tank source and does not naturally degrade even over 20 to 30 years. 

Excavation of contaminated soil is the most effective and economical cleanup method available.  The State assumes that contaminated will be excavated at least as a first step in the cleanup process.  Often contaminated soil excavation is the only cleanup required to allow official incident closure from the State. 

The State considers a soil sample yielding a total petroleum hydrocarbon (TPH) level greater than 10 parts per million to indicate contamination requiring cleanup.  This is a very low level of petroleum.  If soil has a petroleum odor, it is above this standard and requires cleanup.  Again, most tanks have leaked and require cleanup.   

Usually, tank removal is the only way to conclusively and thoroughly assess whether the tank has leaked or not.  We do not recommend taking soil samples by boring beside an underground oil tank.  This practice is not accurate and usually increases the overall cost to resolve the oil tank and associated contamination. 

Cleanup Requirements:  If contaminated soil is discovered, the State's Underground Storage Tank (UST) Section will require that up to 56.8 tons of contaminated soil be excavated during tank removal.  (This is roughly the equivalent of 4 tandem dump truck loads.)  After the appropriate amount of soil is removed, specific soil sampling is required by State regulations and guidelines.  Sampling must be conducted or supervised by a licensed professional. 

Because most oil tanks are buried relatively close to the house foundation, the excavation side wall adjacent to the house must be sloped to ensure sidewall stability and protect the foundation.  Therefore, it is often not possible to remove all of the contaminated soil from the property. 

The Underground Storage Tank Section only recognizes the building foundation of the primary structure as a valid reason to cease excavation in a particular direction.  The State does not accept any of the following items as an acceptable reason to halt excavation efforts and stop removing contaminated soil:  underground utilities, decks, patios, detached carports, driveways, sidewalks, air conditioner and heating units, fences, etc.  Guidance from the State can be requested before beginning excavation.   

Excavation:  Tank removal and contaminated soil excavation is generally conducted over one and a half days.  Immediately after the excavation is complete, the excavation is filled with clean fill material.  A typical excavation size (foot print) is approximately 12 foot by 12 foot area.  The excavation depth depends on the depth to water table, how close the tank is located to the house foundation, and on soil conditions.  We essentially "chase" contaminated soil vertically and horizontally until we have removed all of the contaminated soil that can be safely excavated or until we have reached the maximum tonnage allowed by State Guidelines (56.8 tons). 

Excavation Back Filling:  After contaminated soil has been removed according to Guideline requirements, the excavation is filled with clean fill sand and left bare.  Each property owner can decide whether they want to re-sod, mulch, orre-seed, the excavation area.  Despite packing the fill sand as it is put into the excavation, some settling will occur over time.  Because no one can predict the amount of settling that may occur at your specific property, we will leave the fill material higher that the original grade to offset this anticipated settling. 

For safety reasons, excavations are not left open for more that a few hours. 

Site Impact and Repair:  To remove the contaminated soil and replace it with clean fill material, heavy equipment will have to make numerous trips in and out of your yard.  Because each yard responds differently, it is difficult to predict the exact impact to your yard. 

Please remember that excavating contaminated soil is a one time event and your yard will "repair" over time.  PES will make reasonable attempts to minimize damage to the property.  Ruts and scrapes caused by equipment traffic that are deeper than 2 or 3 inches will be filled with fill sand and leveled even with the land surface unless otherwise directed by the client. 

The excavation event is your one chance to meet the State's cleanup requirements and accomplish the maximum possible cleanup for your property.  With your efforts, rain, and a few growing seasons, your yard will repair. 

Soil Disposal:  Contaminated soil is trucked either to a soil incinerator or to a State permitted "land farm."  Soil transfer to the soil treatment company is documented through disposal manifests which are included in the project reports as required by State guidelines. 

Complete Cleanup vs. State Compliance

At most sites, providing adequate protection for the house foundation does not allow PES to excavate all of the soil that is contaminated above the State's standard.  PES does not guarantee complete and total "cleanup" of a site.  We will conduct all the necessary tasks to bring the site into compliance with the State's requirements.  Most incident sites will probably be closed by the State with a Notice of Residual Petroleum (soil).  Please see our Property Sales and Tanks.

Cleanup Costs:  The average cost of a cleanup is between $15,000 to $20,000.  The non-commercial Trust Fund is available to reimburse you for most of your cleanup costs.  Please see our Trust Fund page for more information. 

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