County takes steps to control stormwater runoff
When Warren County, N.Y., learned that stormwater runoff threatened the water quality of Lake George, it had cause for concern. The 44-square-mile lake provides drinking water and recreational opportunities for 12 towns and villages, and it drives tourism throughout the region. Intent on preserving one of its most valuable assets, the county is engineering a variety of methods to retain and treat the runoff.
The alarm sounded in 1983, when a study by the New York Department of Environmental Control (NYDEC) showed that stormwater runoff from the town of Lake George was flowing down Route 9 and into the Westbrook watershed, which feeds into the lake. As a result, the lake’s ecology was degrading rapidly.
Although the runoff originated in the town’s rapidly growing business district, business owners were unwilling or unable to pay for a stormwater management program. The situation remained unchanged until the mid-1990s, when the Warren County Soil and Water Conservation District (WCSWCD) obtained a state grant for $220,000, allowing it to design a wetland to treat the runoff.
“[There is] a stormwater outfall 100 yards above the southern end of the lake,” says Dave Wick, district manager for WCSWCD. “The wetland design took stormwater from roofs, roads and parking lots, and rerouted [the stormwater] from the outfall to the new wetland.”
The project called for the wetland to be installed on state property, but, just as approvals and engineering were completed, NYDEC ruled that the property could not be used for stormwater treatment. “This turnabout forced us to rethink the solution and to develop a program using the original grant funds to treat the runoff on each individual site,” Wick says.
The resulting program includes installation of stormwater retention and/or treatment systems at up to nine sites, including three hotels, a bowling alley, restaurants and a gas station. Each system — there could be as many as 15 — is being designed by WCSWCD based on the amount of impervious surface at the site and the volume of runoff produced. (More than 14 acres of impervious surface are included in the project area.)
According to Wick, the project will be completed using only the original grant money. To control costs, the county is conducting its own design work.
A variety of technologies are being used at the sites. For example, at one of the hotels, WCSWCD installed a seepage pit and a chamber bed under the lawn. The stormwater enters an 8-foot-high dry well for pre-treatment, then flows to an outfall pipe and into the chamber bed (a StormTech SC-740, manufactured by Old Saybrook, Conn.-based Infiltrator Systems), where it infiltrates the soil.
At other sites, including the gas station, WCSWCD is installing 8-foot-square dry wells under the pavement. Water will enter the wells, which are designed to catch the runoff from up to one inch of rainfall, through a grate. (Ninety percent of runoff pollutants are in the first inch of runoff according to the New York State Stormwater Management Design Manual.) The remaining runoff will revert to Route 9 and flow to the watershed, much as it does now but without the damaging pollutants.
The one-inch standard also comes into play at the bowling alley, where WCSWCD is installing two modified biofiltration trenches in the parking lot. The district is outfitting the 200-foot trenches, measuring 6 feet deep and 7 feet wide, with chamber beds that can infiltrate one inch or more of stormwater. The trenches will be backfilled with stone and landscaped.
According to Wick, many of the stormwater installations will be completed this fall. He expects the work to pay off ecologically as well as economically for the area.
“By looking at each individual site, we have met the overall goal, which is to protect and restore the ecology of Lake George,” Wick says. “The cleaned and treated runoff that results from any of the approaches we are taking will improve water quality and have a positive impact on tourism in the area.”
