The following test method was created by the Ohio Precast Concrete Association for the Proof of Performance of Precast Concrete Onsite Wastewater Tanks.  The photo below show an actual test performed in accordance with the specification language.

     Submit test results of structural proof testing which has been witnessed and certified by a Registered Professional Engineer.  The proof test shall consist of applying a negative air pressure (vacuum) and/or weight applied to the top of the tank to a determined load factor.  For standard tanks designed to be buried with 1 foot to 4 feet of earthen cover, the calculated load factor requires that a tank be tested to a negative air pressure of four (4) inches of mercury plus the placing of 2,000 pounds of weighted material on a footprint of two (2) feet by two (2) feet placed in the center of the top of the tank.  (The calculated load factor is 300 pounds per square foot lateral loads, and 800 pounds per square foot of top loading.)  The tank will be certified as being structurally sound if it holds the pressure and weight for five (5) minutes. Note:  The testing performed under this provision is intended to only be performed in the controlled environment of in-plant testing conforming to industry accepted test procedures.