hello everyone ....my wife & are are building a new home, property has fully engineered septic system installed but never utilized, system was installed in 1998, we are working with septic designer & county for soil perks to move drain & reserve fields, as well as upgrading the overall installed system to 2017 code on a few things ....I dug up to expose the tank that was buried when system was installed in 1998, and my designer says once we expose inlet & outlet pipes, we have to cut & cap them off to accomplish a standing head test, if the tanks passes said test, my wife & I will be able to utilize it ...it is rectangular in shape as per the concrete exposed at the top (about 10 inches under top soil), and probably steel reinforced (but may very well be all concrete) ....I'd like to get some 2nd opinions on what needs to be done and what absolutely should be done in order to give this septic tank installed in 1998 the green light for us to use for our new home ....THANK YOU all for the assist & knowledge pass !!!