Northport looks to control flooding, contamination of harbor

Northport officials are assessing two proposals to address flooding on Main Street and improve the quality of storm water before it runs into the harbor.

Melville-based Nelson, Pope & Voorhis and Ronkonkoma-based J.R. Holzmacher Consulting Engineers on May 24 presented village officials with proposals that would reroute, capture and clean storm water.

The winning vendor would start with a study of the village’s water flow and drainage, and then make specific project recommendations.

Flooding on Main Street is a chronic problem in Northport during heavy rainfalls. The surrounding hills funnel rainwater runoff directly onto the street and into the bay — along with any pollutants it carries.

Addressing the flooding and runoff is the latest in a yearslong effort by village trustees to improve water quality. Their efforts include a $14 million upgrade to the sewage treatment plant that has reduced nitrogen discharge to an average of about 4 pounds per day — down from 18.6 pounds per day in 2013, Trustee Damon McMullen said.

Deputy Mayor Henry Tobin said the flooding has “long afflicted” Main Street, and that the excess water on the road can be hazardous for pedestrians and drivers, erode and damage the roads, and affect businesses on the strip between Ocean Avenue and the water’s edge.

“One of the major reasons Northport provides a high quality of life for residents and businesses is the recreational, commercial and scenic value of our harbor,” Tobin said. “A cleaner harbor enhances all of that.”

The two proposals were similar and will be studied carefully before a selection is made, village officials said.

A key element in both plans is capturing the “first-flush” of storm water — the first flooding in heavy rains carries the most contaminants.

Most of the storm-water pool flows on Main Street at the base of hills at the edge of the harbor, which ultimately feeds Long Island Sound.

The two proposals included the same approaches to reducing flooding and cleaning runoff, including adding more recharge basins and catch basins to the village. Recharge basins capture rainwater and let it soak into the ground, while catch basins collect water and reroute it, typically to recharge basins, Tobin said.

Both companies also proposed incorporating rain gardens — a method of natural landscaping that captures runoff and cleans it through the soil. Rain gardens can filter out nitrogen, phosphorous and other harmful pollutants.

The final combination and placement of the different methods will be determined by the hydrology study, which will analyze the village terrain, including how the hills slope and direct water. Other factors, including the widths of streets and the area’s rainfall patterns, will also be part of the study.

The study will produce a map to help officials prioritize projects over time, eventually addressing flooding and storm-water contaminants beyond Main Street.

“We didn’t just want to cover Main Street; we want to cover more of the village,” Mayor George Doll said.