Weston & Sampson was selected by the Stormwater Coalition of Albany County, New York to analyze and provide data for the feasibility of establishing a stormwater revenue (stormwater enterprise) fund throughout the county. One of the primary tasks of this analysis was the delineation of impervious surfaces for all communities within the county. Two sets of publicly available 4-band aerial imagery sources were used to perform feature extraction that was classified into one of 15 different types of impervious surface based on the use (e.g. airport features, slab/patios, chimney, sports courts, driveways, golf paths/trails, pools, parking, road or travel ways, sidewalks, stadium galleries, tanks, overpasses, and treatment facilities). Weston & Sampson used the fourth band to help optimize feature identification. The near infrared (NIR) band of the aerial imagery was used to confirm surface type (for example, to identify synthetic playing surfaces in stadiums).
Weston & Sampson conducted delineation on all features exceeding 100 square feet of resolution (shed sized). Weston & Sampson evaluated 112,000 individual parcels from 18 different communities, resulting in the delineation of approximately 42-square-miles of impervious surfaces in a total of 340,000 individual features. Our team carefully aligned the roof of building features to the footprint of the building to account for lean within the photos.
Using the impervious area delineations, Weston & Sampson examined potential stormwater fee structures for the communities of Colonie, Menands, and New Scotland using two methodologies: Equivalent Residential Unit (ERU) and Intensity of Development (ID) to determine the potential revenue generated through stormwater program implementation. Weston & Sampson also evaluated stormwater program costs for these communities, including costs for MS4 Permit compliance, drainage system operation and maintenance, and capital improvements.