Just prior to our moving into our house 2 1/2 years ago, the drain field for the septic system was relocated to the opposite side of the tank. The new area seems fine, but the old area is wet and slimy (dark green to black, slick to gel-like stuff... slime mold?), with puddles of water, unless the weather has been very dry for quite some time. There doesn't seem to be any sewer type odor, just kind of musty. The area is fairly high on a slight to medium slope. 

I think they probably just left the original pipes, etc. where they were. Can we fix this without digging everything up? Would something like "Septic-Scrub" work? Thank you for any advice.

Paige