Storm Retention Pond

My partner and I just did a simular thing. It's a little more complicated and expensive than one would think. The pump selection is critical. You will need to start the pump as soon as p[ossible to keep from buying a $1,000,000 pump. But if you don't take cavitation into account, you'll just burn up pumps. Contact me directly with more detail and I'll hook you up with the pump manufacture and the software (trial version) that will help you. I used a hydrology/hydraulics program called HydroCad. The free version will do what calulations for the basin but you will need to do some coversions. First only the pump uses GPM. The hydrology uses CFS. 1 CFS is about 450 GPM.

I just completed a couple projects that involved similar storm drainage pump stations and detention basins. I would suggest contacting a local Civil Engineer specialized in water resources. There are many issues to consider when design a detention pond and pump station that can easily be overlooked in the design process, unless you have been in the practice.

we had numerous storm water DETENTION ponds. gravity outflow to empty in about 24 hours.

one serious problem was that the ponds were built for and by each development. this ensures that there will be kids near and in the pond area. we required 4 ft high fencing, so toddlers cant get in, but adults can climb over to rescue any older kids in trouble. a nearby town had a teenager get sucked into to outlet and drown. we then required an outlet structure made of rebar like material, slanted surface so debris could be raked out while flooded. outer bars of grid structure should be upright rather than horizontal ones to facilitate rake. area of screen should be about 10 times outlet pipe diameter, so water pressure wont hold victim against screen.