Backstory. 2 tanks installed for new house in 2009, a 1500 gal. and a 1000 gal. I suppose they are in series. Not sure. The field lines are of the vaulted type. (i think that's the term). or chambered? Anyway, we rocked along with NO problems either inside or out for 8 years. I figured it was time to get the tanks pumped and did so Dec. '17. Now since this spring, the ground above the tanks (one at least maybe both) is always mushy and the smell is horrific. Grass is greener than ever, though. So, is there anything in the process of pumping a tank that could have caused this to occur or is it indeed just a coincidence? the pumping was done by the same guy that did the install. I wasn't thrilled when he gigged me extra for new tank hatches. He said the landscaper must have cracked them when they put sod out back in '09. Maybe they did. Maybe they didn't.