Moonlight Basin Septic System Website Copyright of VME 2017, all Rights Reserved. The challenging site did not allow for truck delivery, so an excavator and plastic infiltrator tank was used to overcome the challenge and set the tank.. The infiltrator tank is anchored with concrete, bedded with gravel, and properly insulated before final back fill. The first tank supplies a second infiltrator dose tank that also intercepts the original septic tank for the home. After a 685’ dose line, the effluent arrives at the drain field.  The drain field is in an easement that just so happens to be in the middle of a ski run. The county requirement for this drain field was to over dig the trench 2’, bed with sand, then install 3’ wide infiltrator chambers. The drain field is neatly back filled and the ski run is ready for snow and skiing.