Thanks for all the suggestions guys. I agree that a better design would have been to raise the sump returns and keep all low returns on close loops...and I thought I had this project all planned out!! Anyway, at this time I'm not willing to drill more holes in the tank.....probably have too many holes currently. Have decided to take the following precautions..."any input or other ideas would be appreciated"!!
1) install an emergency overflow into the sump plumbed directly into a floor drain
2) install an automatic emergency generator on that pump which will kick on in the event of power failure
3) Ordered two WYE 1 1/2" check valves from SAVKO..these were the best checkvalves I could find...and plumb them in sequence if I can get sufficient flow.
With this setup, the following would have to happen to have the tank drain...1) Power failure 2) Generator fails 3) first valve fails 4) second valve fails
Question....My barracuda pump is able to generate 4000gph at the roughly 4' of head pressure I will have on it. I can only use about 2300 gph due to my overflow limitations. Does anyone know how much two of these valves plumbed in sequence will restrict an original 4000gph flow? Bussboy...are you saying I would be down to 1000gph? I would think differently design valves would result in varying rates of flow restriction?