This work will only delay flooding, not reduce it.

One acre-foot of water (the amount of water covering 1 acre to a depth of 1 foot) equals 326,000 gallons or 43,560 cubic feet of water, and weighs 2.7 million pounds. 

One inch of rain falling on 1 acre of ground is equal to about 27,154 gallons 

Your increased storage is a two-inch rainfall on one acre. How many acres are directing water into the Bannbridge Pond? Hundreds?

As part of our changes to the plans to reflect the removal of the outfall improvements under Beauchamp Rd, we reviewed the proposed pipe sizing under all three roads, and downsized the pipes under Sandyhook so as to maintain storage in upstream swale section and not release more peak storm runoff into the areas around the Pinehurst Rd culvert crossing than is currently going there today. Should the we be able to one day improve conditions under and below Beauchamp Rd, additional capacity at this crossing can always be added at a later date.

Downsizing pipes creates flooding upflow from those pipes. I really question the benefit versus expense of this project. Seems like it is doing something just to be doing something after the basic overall design was compromised. $800,000 is a great deal of money to spend on drainage improvements to reduce flooding when we have no place to put the water.