We are having an inspection on our system. The tank was recently pumped but is full again. We uncovered the d-box and the 2 drainage pits. The water in the d-box is flowing to the pits, however, one pit was full of water and had black sludge on top and the other pit we are having a hard time removing the cover. Since we dug the cover up on the pit we are having trouble with, the water is seeping up through the cover and filling the hole we dug. Why would the water flow through the d-box like normal while the pits are full of water? Can we use your product to clean the pits? Do we have to pump the pits first?