Project Specifics

The “East of Hudson” reservoirs are a series of natural water bodies, mainly in Putnam and Westchester Counties east of the Hudson River north of New York City, that provide much of the city’s drinking water. One of the ongoing threats to these reservoirs is eutrophication, or choking of the water body from the decay of excessive plant material. This excess plant material is mainly due to phosphorus inputs in the form of septic and lawn fertilizer runoff from surrounding residential development in the city’s growing northern suburbs.

The New York State Department of Environmental Conservation (NYSDEC), in order to conduct proactive and effective protection of this vital water resource, selected Geosyntec to provide a variety of technical assistance services to aid in these efforts. Included in this was the development of a manual for the design of stormwater management systems for enhanced phosphorus removal in a document entitled the “East of Hudson Phosphorus Removal Supplement.”

Geosyntec Scope of Services

Geosyntec used the most current runoff and treatment/source control performance data, coupled with continuous simulation hydrologic modeling, to provide a solid technical basis for the recommended design standards to be provided in the supplement. To do this, we relied heavily upon our previous research experience. This includes projects that we have performed for the Water Environment Research Federation (WERF) such as Best Management Practice (BMP) selection and design, as well as the WERF-directed “International Stormwater Best Management Practices Database” project.

Geosyntec also provided analysis, technical support, and summaries of relevant issues in response to comments during a public review period. We then brought our expertise to bear in educating and training attendees in three workshops held around the state of New York for a wide variety of municipal officials, regulators, and others.

Notable Accomplishments

The NYSDEC expanded the phosphorus removal supplement that Geosyntec developed to cover all phosphorus-restricted watersheds throughout the State of New York, which was published in April of 2008 as “Chapter 10 – Enhanced Phosphorus Removal Standards” in the New York State Stormwater Management Design Manual. These standards, as developed as part of this project, comprise the primary design guidance document for protecting the State’s waters from the impacts of increased nutrient loading from development in phosphorus-restricted watersheds.

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