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HomeMy WebLinkAboutSW3180304_Ltr Patterson Kontane_20180321SHABELDEEN ENGINEERING, PA 3145 TATE BLVD ● BOX A ● HICKORY, NC ● 28602 PHONE: (828) 320-7252 CIVIL/WATER/SEWER/ENVIRONMENTAL FAX (828) 394-4126 CONSTRUCTION ADMINISTRATION dan@shabeldeen-engineering.com Ltr Patterson Kontane March 13, 2018 Mr. Robert Patterson, PE NC Dept. of Environmental Quality DEMLR Stormwater Program 512 N. Salisbury St. 1612 Mail Service Center Raleigh, NC 27699-1612 SUBJECT: Kontane Warehouse Additions - Stormwater Permit Application Dear Mr. Harrell: On behalf of May Rivers Properties, LLC (Owner), Shabeldeen Engineering, PA (SE) is submitting the following material for referenced project your review and approval. 1. Stormwater Management Permit Application Form 2. Check for $505.00 3. Operation and Maintenance Agreement 4. Construction Plans 5. Calculations Project Description May River Properties, LLC is the owner of the Kontane Logistics site located on Crawford Road in Statesville (PIN 4756209729). The facility is an existing trucking operation with a warehouse building and loading docks in the middle of the property. The proposed improvements include the addition of two (2) new warehouse/transfer buildings of approximately 60,000 sf and 165,000 sf along with additional parking and access/fire lane. The 60,000-sf building and small parking lot will be constructed in the front of the property along Crawford Road. The 165,000-sf building, parking, and fire lane will be constructed in the rear of the property. The project will be considered “high density” and therefore subject to post-construction stormwater treatment. The site must also comply with the City of Statesville stormwater detention requirements. The existing facility was constructed in 1988, therefore only the new impervious area should require treatment. The City of Statesville agreed to the same for peak attenuation. Since the proposed project will involve two separate parts of the site, we will be allowed to the treat the equivalent combination of existing and proposed impervious areas. Figure 1 shows the new impervious areas and the area that will be treated. Table A lists the new impervious areas and Table B lists the areas to be treated, which excludes the area between the existing and new warehouses and includes the existing north parking lot. The area between the two warehouses will be diverted off-site with the new drainage system Mr. Robert Patterson, PE Page 2 of 2 Kontane Warehouse Additions – Stormwater Permit 3/14/2018 Ltr Patterson Kontane (structures S-21 through S-26). The New Impervious Area is 7.57 acres while the equivalent area to be treated is 8.02 acres. The areas to be treated will be piped to the proposed Wet Pond in the northeast corner of the site. As required, the pond will contain a Forebay and Main Pool. The discharge will be controlled by a 3’x3’ pre-cast concrete control structure as shown on the plans with the following critical components: 1. 2-inch orifice at the Permanent Pool elevation of 901.50 2. Weir slots at the Temporary Pool elevation of 904.25 3. An 18-inch HDPE discharge pipe The 2-inch orifice will discharge the treatment volume in 3.76 days. The weir slots will provide emergency overflow. Based on the accompanying stormwater model results, the maximum water level in the pond for the 100-Year, 24-Hour storm event with the initial water level at 901.50 will be 903.05. This is more than 1- foot below the weir elevation (Temporary Pool Elevation). The storage volume is recovered in approximately 3 days. The 18-inch discharge pipe will convey runoff to the existing 48-inch outfall at the north property boundary. Attached are calculations for the Wet Pond design criteria per Section C-3 of the design manual. All the criteria are met. I appreciate your review and approval of this project. If you have any questions, please do not hesitate to contact me. Sincerely, Dan Shabeldeen, P.E.