Rule 26-2-1.61 - FIREWALLS(a) Each permanent oil and/or saltwater tank or battery of oil and/or saltwater tanks now or hereafter located in the State of Mississippi shall be surrounded by a dike (or firewall) or retaining wall of sufficient height and size so that the volume enclosed shall be equal to one hundred fifty percent (150%) of the capacity of the largest tank in said battery OR the total volume of fluids produced into the said battery during any twenty-four (24) hour period, whichever is the greater. The dike (or firewall) or retaining wall shall be constructed of impermeable material approved in advance by the Field Inspector or Energy Resource Director. If there is more than 150% of the volume of the largest vessel in the tank battery produced into the battery in a twenty-four (24) hour period, the Operator may, in lieu of extending the size of the firewall to accommodate the excess of the 150% of the volume of the largest vessel in the tank battery, install a high level shutdown device or system inside the firewall that would, in the event of a spill, shut down all production coming to the tank battery at a level that would not allow the fluid level to reach within six (6) inches of the top of the firewall. (1) Each permanent oil tank or battery of oil tanks, or any vessel or tank which is protected by a dike (or firewall) or retaining wall and which has installed a drain line for the purpose of discharging rainwater, must have in the drain line a valve on the outside of the firewall and a bull plug installed downstream of the valve. (2) Firewall drain valves may be open and bull plugs removed only when the operator or his representative is present to observe the discharge. Discharges may consist of rainwater only. (3) Firewall drain valves being open or bull plugs being removed from firewall drain lines when no operator personnel are on the location shall be deemed a violation of Statewide Rule 61. (4) The discharge of any fluids or other materials other than rainwater through a firewall drain may constitute a violation of Statewide Rule 16, Statewide Rule 17, Statewide Rule 45 or Statewide Rule 61. (b) In water, swamp or marsh areas where the building of firewalls is impractical or impossible, and the requirement thereof has been waived by the Supervisor upon proper written application, permanent tanks shall be placed on an impervious base and surrounded by an impervious gutter to catch all of the oil and other waste products which, upon escape, may cause a fire hazard or pollution. A sump shall be provided to catch the runoff from the gutters. (c) Tanks for the accumulation of liquid hydrocarbons not falling into the above categories (A and B above) and all facilities for the loading and transportation of liquid hydrocarbons by truck must be surrounded by a retaining wall or must be suitably ditched to a collecting sump, either to be of sufficient capacity to contain the potential spillage to prevent the possibility of pollution of surrounding areas. (d) The Mississippi State Oil and Gas Board may, following notice and public hearing, grant appropriate exceptions to any of the provisions of this rule upon a finding by the Board that alternative construction or operating procedures proposed by the operator will provide an equivalent level of protection to the public and the environment. (e) With respect to oil and/or saltwater tanks, tank batteries and loading facilities in existence on June 17, 2015, the date of approval of amendments to this rule to impose new construction and operating requirements on such facilities, the operator shall have six (6) months from that date in which to comply with said new requirements. MCA Section 53-1-17(3) (1972)