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HomeMy WebLinkAbout20180204 18.017 HydeStreetSubd_Utility ReportMARTINO engineering May 23, 2018 Mr. Tim Wales City Engineer Saratoga Springs, NY 12866 Re: Stormwater Management and Utility Report Hyde Street Subdivision Saratoga Springs, NY 12866 Mr. Wales: Martino Engineering, PLLC, has been retained by the applicant of this project to provide site/civil engineering services in connection with the subdivision application for the Hyde Street, Saratoga Springs, New York 12866, Tax Map Number 165.73-2-41.11. The proposed subdivision of this parcel will result in dividing the single lot into three separate lots. A single-family home and associated driveway and utility connections currently exist on the property. Three single family homes, with utility connection and driveways are proposed. Each home will have 3 bedrooms. Water/Sewer Municipal water and sewer service exists along both Hyde Street and Birch Street, as shown on the subdivision map. The following list provides the utility connection size and location for each lot. Lot 1: 1" (min) Water - Hyde Street 6" Sewer - Hyde Street (Manhole 1) Lot 2: 1" (min) Water - Hyde Street 6" Sewer - Hyde Street (Manhole 2) Lot 3: 1" (min) Water - Birch Street 6" Sewer - Birch Street (WYE) Water and sewer services will be installed per the City of Saratoga Springs standard details. Stormwater Under the City of Saratoga Springs Stormwater Management Regulations, this project is a residential project disturbing less than one acre, and therefore no stormwater management is required. However, stormwater management practices have been added to this project, and designed to mitigate the net increase in impervious area that will result from this project. This Report and the accompanying plans and identify and detail stormwater management practices to mitigate the effects of the increase in impervious area. Stormwater calculations were performed utilizing widely accepted engineering methodologies, including stormwater modeling software HydroCAD (Version 10.00) produced by HydroCAD Software Solutions, LLC, and Technical Release - 55 (TR -55), dated June 1986. P.O. Box 4772 Saratoga Springs, NY 12866 1 518.832.4882 The Natural Resources Conservation Service (NRCS) soil map for the project area indicates soils in the area are Windsor Loamy Sand, with a hydrologic soil group 'A' and indicate greater than 84 inches to seasonal high ground water or bedrock. These are ideal for infiltration practices and a conservative infiltration rate of 5in/hour has been assumed for device sizing. In the current condition, the lot is improved with a +/-2,700 square foot house, which will be demolished as part of this project, and associated +/- 2,000 square foot driveway, for a total of 4,700 square feet of existing impervious area. The proposed impervious areas are as follows: LOT #1: NEW HOUSE AREA: 1,416 SQUARE FEET NEW GARAGE AREA: 416 SQUARE FEET DRIVEWAY: 1,547 SQUARE FEET LOT #2: NEW HOUSE AREA: 1,694 SQUARE FEET NEW DRIVEWAY: 635 SQUARE FEET LOT #3: NEW HOUSE AREA: 1,945 SQUARE FEET NEW DRIVEWAY: 365 SQUARE FEET The total new impervious area is: 8,018 square feet. Drip strips have been proposed at the eves of each home and associated garage on lot one. These have been sized to fully infiltrate the one-year storm. Therefore, it can be assumed that the impervious areas associated with the homes and garage can be reduced from the overall impervious area. As shown below, the reduced (treated) area exceeds the net increase in imperious area. 8,018 SF (New Imp.) - 4,700 SF (Ex. Imp.) = 3,318 SF Net Increase in Impervious Area Total impervious area treated by infiltration device: 5,471 > 3318 (Net Increase) Therefore, with the inclusion of these storwmater treatment devices any impacts associated with the increase of impervious area for this project have been mitigated. In addition to stormwater control devices, Erosion and Sediment control devices have been included in the plans, which shows the minimum controls required to reduce sediment laden runoff during construction. These practices include silt fences, a stabilized construction entrance and a concrete washout area. Sincerely, 1X1.0!in0 Corinna Martino, PE Martino Engineering, PLLC