Backstory. I own a home that has a driveway that slopes towards the garage. The garage has a grill in front of it to catch all the excess water drainage and dump it outside the house, I presume to main drainage on the street. The garage grill drain is on the same plane as the sump pump pit.
The crux of the problem is that if there is really heavy rain then the sump pit will fill up above the inlets even with the sump pump running and cause the garage grill drain to begin accumulating water, so much so that the water flows into the garage causing flooding.
Right now I have installed a 3/4 hp sump pump - which ensures that the sump pit doesn't overflow but unfortunately can't keep up and the water fills above the inlets. I think its only a matter of time.
So long story short, I'd like to add another sump pump in 'parallel' to push water out.
Currently this is my solution:
My question is two fold. Should the 1hp pump be at the bottom or the top? I will be keeping the 3/4hp and would like to utilize it.
Secondly, when both pumps are activated, will there be an issue with flow? Will the PVC explode?