Current through Vol. 42, No. 1, September 16, 2024
(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.
Added at 17 Ok Reg
2857, eff 7-13-00
