Rule 15-18-77-5.1.6 - Minimum Standards for Septic Tank Construction1. General a. All septic tanks manufactured for sale in the state of Mississippi shall bear an imprint identifying the manufacturer, the serial number assigned to the manufacturer's plans and specifications approved by the Department, the liquid or working capacity of the tank and be marked with the date of manufacture. These imprints and markings must be visible at the time of inspection by the Department.b. All openings and lids shall be capable of being sealed in a way that will prevent entrance of surface water and groundwater.c. Tank openings shall be securely fastened or sealed to prevent unwarranted access to the contents of the tanks vandal, tamper and child resistant. Acceptable protection of openings may include, but is not limited to: ii. An "O" ring with twist lock cover requiring special tools for removaliii. Covers weighing sixty-five (65) pounds or more, net weightiv. Stainless steel or other corrosion resistant fasteners for fiberglass or polyethylene lids.2. Prefabricated Concrete Septic Tank a. A minimum twenty-eight (28) -day concrete compressive strength of three thousand (3,000) pounds per square inch must be used in the construction of the septic tank. The concrete must achieve a minimum compressive strength of two thousand five hundred (2,500) pounds per square inch before removal of the tank for the manufactured site. It shall be the responsibility of the manufacturer to certify that this condition has been met before shipment. Accelerated curing in the mold by use of propane gas or other fuels is prohibited, except by accepted methods and upon approval of the Department.b. Lids, walls and bottom thickness must be a minimum of three (3) inches. The bottom and walls must be a monolithic pour. 3. Steel Septic Tanks a. Steel septic tanks must meet Underwriter's Laboratory Standard UL-70 for the tank coating. Only tanks listed as approved under the current published listing will be approved for installation. 4. Fiberglass and Polyethylene Septic Tanks a. Resins and sealants used in the tank manufacturing process shall be capable of effectively resisting the corrosive influences of the liquid components of sewage, sewage gases and soil burial. Materials used shall be formulated to withstand shock, vibration, normal household chemicals, earth and hydrostatic pressure when either full or empty.b. Not less than thirty (30) percent of the total weight of the tank shall be fiberglass reinforcement. Fiberglass tanks with an effective liquid capacity of not over one thousand five hundred (1,500) gallons shall have a minimum wall thickness of 1/4 inch. However, a wall thickness of not less than 3/16 inch will be allowed in small isolated areas of a tank.c. Internal surfaces shall be coated with an appropriate gel coating to provide a smooth, porefree, watertight surface. d. Tanks shall be constructed so that all parts of the tank meet the following mechanical requirements: i. Ultimate tensile strength - minimum twelve thousand (12,000) PSI when tested in accordance with ASTM D 638-89, Standard Method of Test for Tensile Properties of Plastics.ii. Flexural strength - minimum nineteen thousand (19,000) PSI when tested in accordance with D 790-86, Standard Method of Test for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.iii. Flexural modules of elasticity - minimum eight hundred thousand (800,000) PSI when tested in accordance with ASTM D 790-86 , Standard Method of Test for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.e. A test report from an independent testing laboratory is required to substantiate that individual tank design and material formulations meet the requirements of Rule 5.1.6.4.d.15 Miss. Code. R. 18-77-5.1.6