With a $320,000 grant in place from Suffolk County, Southampton Town officials say they hope to begin a two-phase project to reduce stormwater runoff flowing into Mill Pond from nearby farm fields and roadways.
The first phase of the project, a $250,000 redesign of the area where drainage pipes empty into the pond, will begin this fall. The second phase, a larger improvement of drainage along the entire Deerfield Road watershed, extending a mile up from the pond, is scheduled for next spring. Both phases are sufficiently funded, according to Town Director of Municipal Works Christine Fetten.
“We’ll be progressing with phase one … combining the three outfalls into one and putting more drainage capacity on either side of it,” Ms. Fetten said this week. “That won’t filter everything, so we have to do phase two, but we had to start somewhere.”
Last week, the town accepted a $320,000 grant from the Suffolk County Water Quality Protection and Restoration Program. Of that, $257,000 will be dedicated to the work to reduce stormwater runoff into Mill Pond, which has suffered for years from thick algae blooms that have killed fish and aquatic plants. The rest of the grant money will go to upgrades to the town’s GIS mapping systems, to help identify and map areas, townwide, where stormwater runoff problems are originating.
The first phase will renovate a system of drainage pipes that funnel runoff from the broad watershed, much of it farms and polo fields, north of Mill Pond and ending at a turn in Deerfield Road where it runs along the pond’s northeastern shore. Three separate pipes will be combined into one. At the end of the pipe will be a stone splash area, to prevent erosion, and a buffer of plants and shrubs to help filter sediment from the water before it reaches the pond. A swale running down the west side of Deerfield Road and extending about 200 feet up from the pond’s edge will also be cleaned out and redesigned to include check-dams that slow the flow of water, allowing sediment carried in it to settle. The swale will also be vegetated with specially selected plants to capture more sediment and nutrients.
The second phase of the project would extend the system of roadside vegetated swales up Deerfield Road more than a mile, close to the intersection with Edge of Woods Road. Four additional catch basins will be installed along the road to capture runoff at the southern end of the swales. Ms. Fetten said she would like to see several more added further north as well, to further reduce the amount of water that flows toward the pond.
At a recent meeting of the Water Mill Citizens Advisory Committee, some residents worried that phase one of the project would have little impact on the problems that have plagued Mill Pond because it would not actually reduce the amount of nitrogen and phosphorous laden stormwater that reaches the pond. They asked if the town wasn’t just doing the smaller phase because it was inexpensive and would then not proceed with the second portion of the work.
“I think they’ve got the cart before the horse,” said Tom Halsey, whose family works the farmland to the north and east of the pond. “This project is an area about the size of this room. It’s a great idea, but it doesn’t do a thing to clean up the pond.”
Ms. Fetten said this week that those criticisms and concerns are unfounded. The town has funding in place that should be sufficient to complete both phases, as planned, and possibly the addition of the extra catch wells, she said.
The town will go out to bid on the first phase of the project next month and Ms. Fetten said she expects the initial work, to be done this fall, to cost about $200,000. In addition to the county grant, the town also has $293,000 in its capital budget that is earmarked for stormwater runoff abatement that she said will be available for the second phase, along with whatever is left from the grant money. Phase two is projected to cost about $300,000, though Ms. Fetten said that amount is probably somewhat more than what she expects the actual cost will be.
She said that the project will also take place entirely on town-owned land, mostly within public right-of-ways for Deerfield Road, rather than requiring the use of some private land, as early sketches of the project appeared to show.
In April, the town spent some $250,000 on an experimental application of a mineral compound that is intended to absorb phosphorous out of the pond’s water and starve the destructive algae blooms of their main food source. A second application is scheduled for next spring, but engineers and scientists have said that if the amount of nitrogen being injected into the pond by runoff following heavy rains is not reduced, the applications will be significantly less effective.
Shortly after the first application of Phoslock three rainstorms in less than two weeks dumped 12 inches of rain on the surrounding land, creating rivers of muddy water that flowed down Deerfield Road and into the pond.