Permeable resin-bound surfacing can be proposed as a stormwater practice in Westchester when it is designed as porous pavement under the New York State Stormwater Management Design Manual: a porous surface over an open-graded stone reservoir, on soils that infiltrate or with an underdrain. The manual does not name resin-bound, so the reviewer decides whether it qualifies. Where your property sits in the county matters more than almost anything else, because the northern towns drain to New York City's drinking water reservoirs and the Sound Shore drains to Long Island Sound.
In the watershed towns, permit thresholds are lower and phosphorus treatment is stricter. Everywhere, an overlay on an existing slab is only a finish; the water still runs off the pavement beneath, and it should not be offered as stormwater control.
Two sets of rules: the NYC watershed and everywhere else
Westchester County Planning lists twelve municipalities with land in the New York City watershed: Bedford, Cortlandt, Harrison, Lewisboro, Mount Pleasant, New Castle, North Castle, North Salem, Pound Ridge, Somers, Yorktown and Mount Kisco. Inside the watershed boundary, NYSDEC's construction general permit, GP-0-25-001, applies to disturbances of 5,000 square feet or more, against one acre in most of the state. The permit also lists the entire NYC watershed east of the Hudson as an enhanced phosphorus removal watershed.
In those watersheds the state Design Manual sizes the water quality volume to the 1-year, 24-hour storm, and the permit's impaired-waters list includes phosphorus listings such as the Saw Mill and Sheldrake rivers and lakes such as Lake Mohegan and Teatown Lake. Porous pavement is one of the manual's runoff reduction techniques, so a well-designed permeable section can count toward that volume if the reviewer accepts the surface. Each city, town and village also enforces its own stormwater local law as an MS4 operator.
Rock, till and the Sound: conditions the engineer will weigh
Much of the county is glacial till over shallow bedrock, with better-draining pockets in some valleys. On rocky ground the manual's numbers matter: porous pavement needs a measured infiltration rate of at least 0.5 inch per hour, an underdrain when the rate is under 2 inches per hour, and 2 feet of clearance from bedrock or the seasonal high water table. On rocky northern lots, that often means an underdrained section with a filtering base rather than full infiltration.
Along the Sound Shore, from New Rochelle to Rye and Port Chester, low ground, tides and flashy streams such as the Mamaroneck and Sheldrake drive flooding. The manual also notes nitrogen's role in Long Island Sound hypoxia. Winter adds freeze-thaw and plowing, and the manual bars sand on porous pavement. Your engineer may combine an open-graded aggregate reservoir with Rock Crete or another permeable base.
Where Westchester projects use it
- Estate driveways, motor courts and garden walks in the northern watershed towns, where disturbing 5,000 square feet or more triggers state permit coverage and an erosion and sediment control plan, and larger projects can add phosphorus treatment.
- Corporate and institutional campuses along the I-287 corridor replacing aging lots and plazas.
- Village downtown and train-station areas in the river towns, where sites are tight and storm sewers are old.
- Clubs, schools and waterfront properties on the Sound Shore that need to slow runoff toward flood-prone streams.
Hotspots such as fueling or vehicle maintenance areas are excluded; the manual does not allow porous pavement to treat them.
Getting a permeable design through review
Most approvals come from the local planning board, building department and town or village engineer acting as the stormwater management officer under the municipal local law. Projects in the NYC watershed can also face review by the New York City Department of Environmental Protection under its watershed regulations, and state permit coverage where thresholds are met. Bring soil tests, a phosphorus calculation where required, and a maintenance plan.
Resin Rock's role is supply and support: binder, stone, trims and Rock Crete, with technical data sheets the engineer can cite in the SWPPP or local stormwater plan. An approved installer, matched through us, does the work, and New York contractors can train with us through installer training. Whether the surface counts toward phosphorus or runoff reduction is up to the reviewer.
Before you specify permeable resin-bound in Westchester
- Check whether the parcel is inside the NYC watershed using the county's Croton-Kensico map.
- Count disturbance against the 5,000 square foot watershed threshold.
- Test infiltration and depth to bedrock at the paved footprint.
- Run the phosphorus or water quality volume calculation where the permit or local law requires it.
- Keep fueling and service areas off the permeable section.
- Plan winter maintenance without sand.
Common questions about permeable resin-bound in Westchester
Does my Bedford or Somers driveway project need a state stormwater permit?
It might. In the New York City watershed east of the Hudson, NYSDEC's construction permit applies when disturbance reaches 5,000 square feet, far below the one-acre threshold elsewhere. A large driveway, motor court or pool area can cross that line. Between 5,000 square feet and one acre, the permit calls for an erosion and sediment control plan; phosphorus treatment can apply to larger projects, though your town's law may ask for more. Your engineer should confirm coverage before design.
Can permeable resin-bound count toward phosphorus treatment?
Porous pavement is a recognized runoff reduction practice in the state Design Manual, and in enhanced phosphorus watersheds the treatment volume is based on the 1-year, 24-hour storm. Whether a resin-bound surface course is accepted as porous pavement is a reviewer decision, so raise it early with the municipal engineer and, where applicable, DEP.
We are on the Sound Shore. Will it stop our yard from flooding?
It can store some rain from the paved area itself, but it will not hold back tidal or stream flooding. On low lots, high groundwater may force an underdrained design. Treat it as one part of a drainage plan that also addresses roof water, grading and outlets, designed by an engineer.
Official sources for Westchester
- Westchester County Planning: Watershed Planning
- NYSDEC Stormwater Permit for Construction Activity (GP-0-25-001)
- New York State Stormwater Management Design Manual (July 31, 2024)
Local rules change. We last checked these sources in October 2026. Confirm current requirements with the reviewing agency before you design, and treat this page as a starting point, not engineering or permitting advice.