SECTION 35:30-29-35. Secondary containment for commercial storage facilities

(a)   Capacity/diking. The diked area for containment of commercial storage facilities shall contain, below the height of the dike, 110% of the volume of the largest storage tank within the diked area.

(b)   Walls. The walls of a secondary containment facility shall be constructed of earth, steel, concrete, or solid masonry, or other material specifically approved by the control official, and be designed to withstand a full hydrostatic head of any discharged fluid and weight load of material used in construction.

(1)   Cracks and seams shall be sealed to prevent leakage.

(2)   Walls constructed of earth or other permeable material shall be lined.

(3)   Earthen walls shall have a horizontal to vertical slope of at least 3 to 1, unless a steeper slope is consistent with good engineering practice, and shall be packed and protected for erosion.

(4)   The top of earthen walls shall be no less than 2.5 feet wide.

(5)   Walls may not exceed 6 feet in height above interior grade unless provisions are made for normal access and necessary emergency access to tanks, valves, and other equipment, and for safe exit from the secondary containment facility.

(6)   Walls constructed of concrete or solid concrete shall rest upon a floating base, or upon suitable concrete footings.

(c)   Lining.

(1)   The base of a secondary containment facility, and the interior of any earthen walls of the facility shall be lined with asphalt, concrete, an approved synthetic liner, or a clay soil liner or other liners approved by the control official designed to limit permeability of the base and walls while compatible with the stored product. Liners shall meet the requirements of this subsection. Geocomposite liners, such as a layer of sodium bentonite encapsulated between layers of geotextile are considered synthetic liners.

(2)   Asphalt or concrete liners shall be designed according to good engineering practices to withstand any foreseeable loading conditions, including a full hydrostatic head of discharged fluid and static loads of storage containers, including appurtenances, equipment and contents. Cracks and seams shall be sealed to prevent leakage.

(3)   Synthetic liners and installation plans shall be approved by the control official. A synthetic liner may not be approved by the control official until the manufacturer of the liner provides the control official with a written confirmation of compatibility, and a written estimate of the life of the liner. Synthetic liners shall be installed under the supervision of a qualified representative of the manufacturer or professional engineer, and all field constructed seams shall be tested, and repaired if necessary, in accordance with the manufacturer's recommendations.

(4)   The surface soil liner shall be sealed, including the berm of an earthen dike with a sealing agent such as sodium bentonite, attapulgite, or a similar clay material. The liner shall be constructed in accordance with reliable civil engineering practices, to achieve a coefficient of permeability not to exceed 1 x 10-6c,sec, with a thickness of not less than 6 inches. The floor and internal walls of the containment area shall have a protective barrier at least equivalent to 6 inches of sand, soil, or gravel to limit desiccation, evaporation, freeze/thaw cycling, or other physical damage.

(5)   A liner need not be installed directly under a storage tank having a capacity of one hundred thousand (100,000) gallons or more which has been constructed on site and put into use prior to the effective date of this rule provided that one (1) of the following alternative procedures are compiled with, certified to in writing by an official of the company which owns the tank, and the certificate is filed with the control official:

(A)   Monitoring devices shall be installed in angled borings under each tank. These monitoring devices shall constitute a leak detection system for each tank in advance of the point at which any leak would reach groundwater.

(B)   The number, length, and depth of each boring shall be determined on the basis of site characteristics. The array of monitoring devices under each tank shall constitute the best practical early warning detection system for tank leakage.

(C)   Each monitoring plan under this alternative shall be implemented only upon review and approval of the control official.

(d)   Elephant rings.

(1)   Individual storage tanks may be contained with a secondary storage container ("elephant ring") in lieu of a diked containment area. The "elephant ring" serves as a second containing wall in the event that the primary storage tank develops a leak.

(2)   Both the primary storage tank and the "elephant ring" shall be fabricated of material compatible with each other and with the fertilizer being stored. Dissimilar metals between the primary storage tank and the "elephant ring" contribute to electrolytic corrosion and this use is prohibited, unless provisions are made to prevent the corrosion.

(3)   The height of the "elephant ring" wall shall not exceed 4 feet unless provisions are made for escape should flooding occur. The volume contained within the secondary storage walls up to the working height of the "elephant ring" shall be sufficient to contain a volume 10% greater than the volume contained in the primary storage tank plus the volume displaced by the footings of any equipment (i.e., pumps, meters, etc.) placed within the secondary containment vessel.

(4)   The "elephant ring" shall be free of leaks and structural defects. The base shall be protected from corrosion, both from inside and outside, and shall be underlain by a concrete pad or with eight inches of compacted gravel beneath four inches of compacted sand, or clay, or as recommended by the manufacturer of the "elephant ring" and approved by the control official.

(5)   All piping connections to the primary storage tank shall be made over the wall of the "elephant ring" and shall be adequately supported and braced. Pumps and other fixtures, if located within the "elephant ring" containment structure, shall be placed on an elevated platform above the top of the elephant ring or protected from flooding.

(6)   Accumulations of storm water and other material shall be promptly removed from the "elephant ring". The "elephant ring" shall not have floor or wall drains for this purpose, but pumps or other over-the-wall methods may be used. Precipitation shall be reused where possible, or disposed of according to state and local regulations.

(e)   Drainage from secondary containment areas. No fertilizer secondary containment areas, or existing containment areas having major renovation, shall have a relief outlet and valve. The base shall slope to a collection point where storm water can be removed from the secondary containment area by pumping or other means. Precipitation shall be reused where possible, or disposed of according to state and local regulations.

(f)   Inspection and maintenance requirements.

(1)   Every secondary containment shall be inspected by the operator of the storage facility at intervals of not greater than six months and be maintained as necessary to assure compliance with these rules.

(2)   All secondary containment areas shall be maintained free of debris and foreign matter.

(g)   Secondary containment exemption. Secondary containment shall not be required for storage tanks equipped with a synthetic liner inside the tank if installed under the supervision of a qualified representative of the manufacturer or professional engineer. All field constructed seams shall be tested and repaired in accordance with the manufacturer's recommendations. The manufacturer of the liner shall provide the control official a written confirmation of compatibility for the product stored and a written estimate of the life of the liner.

[Source: Added at 17 Ok Reg 2857, eff 7-13-00]