15A NCAC 02L .0406. DISCHARGE OR RELEASE CLASSIFICATIONS

The Department shall classify the risk of each known discharge or release as high, intermediate or low risk unless the discharge or release  has been classified under 15A NCAC 02L .0404(3) of this Section.  For purposes of this Section:

(1)           "High risk" means that:

(a)           a water supply well, including one used for non-drinking purposes, has been contaminated by the release or discharge;

(b)           a water supply well used for drinking water is located within 1000 feet of the source area of a confirmed discharge or release;

(c)           a water supply well not used for drinking water is located within 250 feet of the source area of a confirmed discharge or release;

(d)           the groundwater within 500 feet of the source area of a confirmed discharge or release has the potential for future use in that there is no source of water supply other than the groundwater;

(e)           the vapors from the discharge or release pose a serious threat of explosion due to accumulation of the vapors in a confined space; or

(f)            the discharge or release poses an imminent danger to public health, public safety, or the environment.

(2)           "Intermediate risk" means that:

(a)           surface water is located within 500 feet of the source area of a confirmed discharge or release and the maximum groundwater contaminant concentration exceeds the applicable surface water quality standards and criteria found in 15A NCAC 02B .0200 by a factor of 10;

(b)           in the Coastal Plain physiographic region as designated on a map entitled "Geology of North Carolina" published by the Department in 1985, the source area of a confirmed discharge or release is located in an area in which there is recharge to an unconfined or semi-confined deeper aquifer which the Department determines is being used or may be used as a source of drinking water;

(c)           the source area of a confirmed discharge or release is within a designated wellhead protection area, as defined in 42 U.S.C. 300h-7(e);

(d)           the levels of groundwater contamination for any contaminant except ethylene dibromide, benzene and alkane and aromatic carbon fraction classes exceed 50 percent of the solubility of the contaminant at 25 degrees Celsius or 1,000 times the groundwater standard or interim standard established in 15A NCAC 02L .0202, whichever is lower; or

(e)           the levels of groundwater contamination for ethylene dibromide and benzene exceed 1,000 times the federal drinking water standard set out in 40 CFR 141.

(3)           "Low risk" means that:

(a)           the risk posed does not fall within the high or intermediate risk categories; or

(b)           based on review of site-specific information, limited assessment or interim corrective actions, the Department determines that the discharge or release poses no significant risk to human health or the environment.

If the criteria for more than one risk category applies, the discharge or release shall be classified at the highest risk level identified in 15A NCAC 02L .0407 of this Section.

 

History Note:        Authority G.S. 143-215.2; 143-215.3(a)(1); 143-215.94A; 143-215.94E; 143-215.94T; 143-215.94V; 143B-282; 1995 (Reg. Sess. 1996) c. 648,s. 1;

Recodified from 15A NCAC 02L .0115(d);

Amended Eff. December 1, 2005.