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HomeMy WebLinkAboutSP-22-057 - Supplemental - 0002 Baldwin Avenue 208 Flynn Avenue, Suite 2A, Burlington, VT 05401  Tel: 802-863-6225 85 Mechanic Street, Suite E2-3, Lebanon, NH 03766  Tel: 603-442-9333 414 Union Street, Schenectady, NY 12305  Tel: 518-205-9141 Narrative, Location Map and Soils Map Orchard School, ZEM Classrooms 1. Introduction Engineering Ventures, PC are writing on behalf of the South Burlington School District to apply for a State Stormwater Discharge Permit pursuant to General Permit 3-9050 for the above referenced project. 2. Project Description The ZEM (Zero Energy Modular) Classrooms project involves the placement of pre-constructed modular classrooms at an existing public elementary school, the addition of a hallway to connect the two, and minor site updates. These classrooms are intended to serve the emerging need due to an increase in population and are planned to remain on site for three to eight years. The project requires a permit as the impervious surface expansion is greater than 5,000 square feet resulting in a total impervious area greater than one acre. The campus is also a 3-Acre site which is currently undergoing Engineering Feasibility Analysis by VHB, Inc. through the Green Schools Initiative. The proposed practice is intended to treat and manage all stormwater associated with this project and not encroach on the greater campus or affect the ability to comply with 3-Acre requirements. 3. Existing Condition The existing campus is comprised of approximately 13.5 acres and includes a school building, three parking areas, vehicle and pedestrian access to Baldwin Avenue, recreation fields, playgrounds, and wetlands. The existing impervious cover is approximately 3.5 acres. The project area is approximately 0.4 acres located south of the existing building. The mapped soils in the project area are Belgrade and Eldridge and Enosburg and Whately, 0-3% slopes, hydrologic group C/D. Some soils in the project area are hydric and all are undrained. The entire site is located in the North Brook / Shelburne Bay Watershed. 4. Existing Stormwater System (remove if not applicable) The project area has a stormwater catchment system consisting of area drains which discharge to the municipal system on Baldwin Avenue. 5. Proposed Stormwater System: a) Description of Impervious Area: 0.158 acres of new roof b) Receiving Body: North Brook c) Fish Habitat Designation for Receiving Water: Cold d) Description of compliance with each of the treatment standards in the 2017 VSMM including the treatment practices or waivers used to meet each of the following standards: i) Post-Construction Soil Depth and Quality Standard: Met through a combination of Options #1 and #3 per §3.2 of the VSMM ii) Groundwater Recharge Standard: Waiver requested due to D soils 208 Flynn Avenue, Suite 2A, Burlington, VT 05401  Tel: 802-863-6225 85 Mechanic Street, Suite E2-3, Lebanon, NH 03766  Tel: 603-442-9333 414 Union Street, Schenectady, NY 12305  Tel: 518-205-9141 iii) Water Quality Treatment Standard (WQV): Met with the gravel wetland iv) Channel Protection Standard (CPV): Met with the gravel wetland v) Overbank Flood Protection Standard (QP10): Met with gravel wetland vi) Extreme Flood Protection Standard (QP100): Waiver requested due to less than 10 acres of impervious cover The following items are included for review: · eNOI form submitted via ANROnline · Narrative: Narrative, Location Map and Soils Map · Workbooks: STP Selection Tool and Standards Compliance Workbook · Worksheets: STP and Waiver Worksheets · Modeling: Runoff modeling and calculations · Plans: Pertinent plan sheets · Plan Set Reference: List of all applicable plans Map created using ANR's Natural Resources Atlas 31,683 5,280.5 South Burlington Orchard School Temp. ClassroomsVermont Agency of Natural Resources 24,000 © Vermont Agency of Natural Resources 4,000.0 1: WGS_1984_Web_Mercator_Auxiliary_Sphere Feet4,000.00 NOTES LEGEND2,000.00 vermont.gov DISCLAIMER: This map is for general reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. ANR and the State of Vermont make no representations of any kind, including but not limited to, the warranties of merchantability, or fitness for a particular use, nor are any such warranties to be implied with respect to the data on this map. November 28, 2022 THIS MAP IS NOT TO BE USED FOR NAVIGATION 1" = 2000 1cm = 240Ft.Meters Roads Interstate US Highway; 1 State Highway Town Highway (Class 1) Town Highway (Class 2,3) Town Highway (Class 4) State Forest Trail National Forest Trail Legal Trail Private Road/Driveway Proposed Roads PROJECT LOCATION Hydrologic Soil Group—Chittenden County, Vermont (South Burlington Orchard School) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/28/202249221504922200492225049223004922350492240049224504922150492220049222504922300492235049224004922450642450642500642550642600642650642700642750642800642850642900 642450 642500 642550 642600 642650 642700 642750 642800 642850 642900 44° 26' 28'' N 73° 12' 37'' W44° 26' 28'' N73° 12' 14'' W44° 26' 18'' N 73° 12' 37'' W44° 26' 18'' N 73° 12' 14'' WSoil Map may not be valid at this scale. N 0 100 200 400 600 Feet Map Scale: 1:2,280 if printed on A landscape (11" x 8.5") sheet. Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 Soil Rating Polygons A A/D B B/D C C/D D Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI AdB Adams and Windsor loamy sands, 5 to 12 percent slopes A 4.4 32.1% BlA Belgrade and Eldridge soils, 0 to 3 percent slopes C/D 6.8 50.3% EwA Enosburg and Whately soils, 0 to 3 percent slopes C/D 2.3 17.1% HnA Hinesburg fine sandy loam, 0 to 3 percent slopes A 0.1 0.4% Sd Scarboro loam A/D 0.0 0.2% Totals for Area of Interest 13.6 100.0% Hydrologic Soil Group—Chittenden County, Vermont South Burlington Orchard School Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/28/2022