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Incident Closure Scenarios

Fuel oil on top of the water table. As much as 4 feet of fuel oil has been measured floating on top of the water table at a residential property in the Wilmington area.

After contaminated soil excavation and  the required soil and groundwater assessment, an underground tank property can be placed in one of the incident closure categories listed below.  These categories are based on the soil and groundwater analytical results and on the State's statues, regulations, and guidelines. 

Worst

1) Worst Case:  fuel oil measured on the water table (12%) 

The State will not officially close the contamination incident but will not require any further action "at this time."

Implications:

The site is in compliance with the State of North Carolina statues and regulations, but additional work may be required at a later date.    

Trust Fund reimbursement will be available if future work is required.  Elective fuel recovery may or may not be reimbursed by the Trust Fund. 

Fuel floating on the water table tends to remain localized in the area of the former tank location. 

2) Bad:  contaminated groundwater is discovered (21%)

The State will either:

  1. not officially close the contamination incident but will also not require any further action "at this time" (11%) or
  2. the State will close the contamination incident with a Notice or Residual Petroleum for groundwater (10%). 

Implications:

All tank responsibility and cleanup requirements have been met (situation B). 

The site is in compliance with the State of North Carolina statues and regulations (situation A and B), but additional work may be required at some later date (situation A). 

Trust Fund reimbursement will be available if future work is required. 

Contaminated groundwater tends to remain localized in the area of the former tank. 

Installation and use of an irrigation well will not be allowed on a property in this category  (This is to protect the property occupant from potential health impacts by eliminating potential exposure to petroleum contaminated groundwater.)  To officially close this type of contamination incident, any existing irrigation well will have to be abandoned according to North Carolina well regulations (situation B). 

A Notice of Residual Petroleum (NRP) can be removed from the Register of Deeds if it is demonstrated to the State that groundwater levels have dropped to acceptable levels.  Groundwater analysis to document this drop are not reimbursed by the Trust Fund. 

Property buyers are must realize that a NRP is common for houses that had an underground oil tank (most houses built before 1975). (It needs to be accepted similar to lead paint issues.)

Often contaminated soil excavation is the only cleanup that is required.

3) OK: contaminated soil remains after excavation efforts (23%):

The State will officially close the contamination incident with a Notice or Residual Petroleum (NRP) for soil (only).

Implications:

All tank responsibility and cleanup requirements have been met. 

The site is in compliance with the State of North Carolina statues and regulations and is officially closed. 

The State has determined that there is no imminent threat to public health or the environment.  Human contact with contaminated soil noted in the NRP should be avoided.

Property buyers are must realize that a NRP is common for houses that had an underground oil tank (most houses built before 1975).  (It needs to be accepted similar to lead paint issues.) 

Very Good: all contaminated soil is excavated (31%):

The State will officially close the contamination incident because all of the contaminated soil was excavated from the property and no groundwater contamination exists. 

Implications:

All contamination has been removed from the site. 

All tank responsibility and cleanup requirements have been met. 

The site is in compliance with the State of North Carolina statues and regulations and has been cleaned up to State standards. 

5)  Best:  no contamination discovered (12%):

Soil sample results document that no soil contamination is present; the tank did not leak. 

Implications:

No contamination was discovered at the site. 

The site is in compliance with the State of North Carolina statues and regulations. 

All tank closure actions are documented for future reference and review. 

* These percentages are calculated based on 65 tank removal projects from February 2006 to April 2008.  All tanks during this time frame were discovered to be leaking.  However, we have integrated the statistics on these 65 tank removals with our 7 year tracking history to arrive at the percentages presented here.   

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