One of the eight major streams entering Lake George, English Brook has been of high concern to the Association for over a decade. Land development in the English Brook watershed has increased the volume and velocity of stormwater runoff, leading to increased pollution entering the brook. The New York State Department of Environmental Conservation (DEC) lists the brook as sediment impaired, and its delta is one of the largest on the Lake. According to National Urban Runoff Program reports conducted during the 1980s, English Brook has high levels of total phosphorus, chlorides, total suspended sediments, lead and nitrate-nitrogen.
The grant will partially fund the installation of a $48,400 Aqua-Swirl hydrodynamic separator on the east side of Rt. 9N at the Lochlea Estate in the town of Lake George. The system will collect previously untreated stormwater runoff from both the east and west sides of Rt. 9N, as well as the bridge between the two exits at Exit 22 on Interstate 87. The majority of the runoff in the 48-acre watershed will be captured and treated.
Other stormwater solutions requiring a larger footprint were explored but were not possible due to the shallow soil depth and high bedrock found throughout the site. The Aqua-Swirl unit has a small footprint and a suitable location was found near existing stormwater infrastructure.
The project is also taking the opportunity to capture untreated stormwater runoff from the west side of the road. By installing some additional infrastructure, stormwater from both sides of the road will be directed to the new unit.
The cost of the entire project is estimated at $117,000. In addition to the Lake Champlain Basin Program grant, funding for this project has been secured from the Lake George Watershed Coalition and the Helen V. Froehlich Foundation. The village of Lake George will maintain the structure and clean out the system using the LGA’s Catch Vac.
How does an Aqua-Swirl Hydrodynamic Separator work?
Stormwater enters an Aqua-Swirl unit through an inlet pipe, producing a circular flow that makes contaminates settle. A swirl concentrator removes the gross pollutants; a filtration chamber then removes fine sediment and waterborne pollutants. A combination of gravity and hydrodynamic forces encourages solids to drop out of the flow and migrate to the center of the chamber, where velocities will be lower. The Aqua-Swirl also retains water between storms, allowing for settling of inorganic solids when the water is not flowing.
Additional work protecting the English Brook Watershed
Significant work in the English Brook watershed has already been completed by the LGA in conjunction with Warren County Soil and Water Conservation District (WCSWCD). In 2009, design work for a 150-foot-long sediment basin at the mouth of the brook was completed. Permits for this project have been submitted to the appropriate agencies. The basin will be about 6 feet deep with a capacity to trap over 700 cubic yards of material. Further upstream, at the Hubble Reservoir, the LGA hired Galusha Construction to remove a non-functioning sluice gate and valve that were making it difficult to maintain the site. The site was dewatered and almost 600 cubic yards of sediment were removed. The LGA acquired funding for both projects through grants from the Helen V. Froehlich Foundation and the New York State Department of State and the Environmental Protection Fund.
Once this important upland work is completed, the culminating step is to remove the sediment that has built up in the delta over the course of generations. The nutrient-rich sediment in deltas supports invasive plant growth, hampers fish spawning, and harbors nuisance waterfowl. By removing the delta, safe navigation is restored, the health of the Lake’s fisheries improves, the Lake returns to its original bottom, and property values are retained.
Photo: The English Brook delta in Lake George taken by the LGA in November 2010.