The City of Plattsburgh (City) is the most urbanized area within the New York State Lake Champlain
Basin. Land-use varies from residential areas with small and large parks and schools to the industrial
sections and the highly commercialized downtown. All of these areas contribute to the imperviousness
of the land within the City, which creates a large amount of stormwater runoff that is conveyed through
the City’s sub-surface separate stormwater sewer system to 41 outfalls that discharge directly to Lake
Champlain, the Saranac River and their tributaries within the City.
In an effort to fully understand the conveyance of stormwater within the City and identify vulnerabilities
within the stormwater system, the City undertook an extensive mapping project that included
identification and data collection for all stormwater trunklines. Information was digitized from existing
paper maps, as well as collected by City staff throughout the summer of 2013, and includes data on
storm sewer manholes, catch basins, storm sewer mains and combined sewer mains. This information
was then utilized within the US EPA SWMM computer model to complete sub-sewershed mapping,
which ultimately identified 54 principle sub-sewersheds within the City’s system, and identify areas
within the City that are or will be prone to flooding during 5-year, 10-year, 25-year, 50-year and 100-
year design storm scenarios. Outcomes of the modeling include the identification of the manholes that
surcharge above rim elevation and identification of the areas with an increase in flood volume
throughout the City as the higher intense storms transpire.
Information obtained from the modeling was then used to identify 12 City or school district owned sites
directly within or adjacent to flood prone areas that can be used as sites for green infrastructure retrofit
project implementation. The sites were ranked based on a matrix created by the project partners that
takes into consideration project achievability, stormwater volume reduction potential and stormwater
quality impacts. Of the 12 projects, the US Oval parking lot was ranked as the highest for
implementation, and use of green infrastructure practice ranking matrix indicated that a bioretention
area would reduce water quantity while improving water quality at the site.
In the spring of 2015 the City constructed a bioswale and bioretention basin at the US Oval that was
designed to collect stormwater from 2.5 acres, of which 1.5 acres is impervious surface. The bioswale
was constructed to convey at least 4.6 cfs, and is connected to the bioretention basin via an
underground pipe. A basin area of 1200 square feet with total volume of 9700 cubic feet was
constructed to receive 8300 cubic feet of water quality volume. The basin also contains several
New York native plant species, and two educational signs have been installed at the site.
On July 27, 2015, a ribbon cutting was held at the basin to mark the opening of the first green
infrastructure project within the City of Plattsburgh. Members of the press, as well as residents, attended
the event to learn about the project and become educated on the City’s plans to continue addressing
stormwater runoff in the future.