15A NCAC 02N .0504 METHODS OF RELEASE DETECTION FOR TANKS
(a) The regulations governing "Methods of release detection for tanks" set forth in 40 CFR 280.43 (Subpart D) are hereby incorporated by reference, except that 40 CFR 280.43(f)(3), (f)(4), and (f)(5) shall not be adopted by reference.
(b) Wells used for monitoring or testing for free product in the groundwater shall be:
(1) Located as follows:
(A) for new installations, within and at the end of the excavation having the lowest elevation and along piping at intervals not exceeding 50 feet; or
(B) for existing installations, in the excavation zone or as near to it as technically feasible and installed in a borehole at least four inches larger than the diameter of the casing;
(2) A minimum of two inches in diameter. The number of wells installed shall be sufficient to detect releases from the UST system;
(3) Equipped with a screen that extends from two feet below land surface to a depth of 20 feet below land surface or two feet below the seasonal low water level, whichever is shallower. The screen shall be designed and installed to prevent the migration of natural soils or filter pack into the well while allowing the entry of regulated substances into the well under both high and low groundwater level conditions;
(4) Surrounded with clean sand or gravel to the top of the screen, plugged and grouted the remaining distance to finished grade with cement grout;
(5) Constructed of a permanent casing and screen material that is inert to the stored substance and is corrosion resistant;
(6) Developed upon completion of installation until the water is clear and sediment free;
(7) Protected with a water-tight cover and lockable cap;
(8) Labeled as a liquid monitor well; and
(9) Equipped with a liquid leak detection device continuously operating on an uninterrupted basis; or
(A) For tanks storing petroleum products, tested at least once every 14 days with a device or hydrocarbon‑sensitive paste capable of detecting the liquid stored; or
(B) For tanks storing hazardous substances, sampled and tested at least once every 14 days for the presence of the stored substance.
(c) Wells used for monitoring or testing for free product in the groundwater at new installations and constructed in accordance with Paragraph (b) of this Rule shall be deemed to be permitted in accordance with the requirements of 15A NCAC 02C .0105.
(d) Any person completing or abandoning any well used for testing of vapors or monitoring for free product in the groundwater shall submit the record required by 15A NCAC 02C .0114(b).
(e) Wells used for monitoring for the presence of vapors in the soil gas of the excavation zone shall be equipped with a continuously operating vapor detection device or tested at least once every 14 days for vapors of the substance stored.
History Note: Authority G.S. 143‑215.3(a)(15); 143B‑282(a)(2)(h); 150B‑21.6;
Eff. January 1, 1991;
Amended Eff. June 1, 2017.