Anyone here with experience with the plastic domes that bury in place of perforated pipes with gravel or shredded tires? I have a situation where I will need a large surge capacity and thought that was a good way to get it instead of installing a LOT more pipe in a LOT more feet of trench.

I will be installing two septic tanks. One will be a standard gravity flow system and the other will have a demand pump on the last chamber to pump the water uphill to where the gravity tank outputs to the input of the leach field.

I have been advised that the lower and upper pump settings should be set as far apart as is practical to minimize the number of times the pump cycles. The one septic guy I discussed the installatlion with disagreed with me on this point: Since in "normal" use the output chamber overflows to the leach filed in a per flush or per bath or per laundry load manner there is not a huge volume all at once AND the output chamber stays full to the overflow point all the time. When pumping the output up hill with maximized volume per cycle you pump the output tank way down each time. I thought there should be an extra chamber or another tank that would receive the normal output and store it for "batch" pumpouts. The septic tank would then work just like in a "normal" gravity setup. This would still leave the problem of handling the surges during pumpout which is why I was considering the domed plastic chambers, for their surge capacity.

Thoughts?

Pat