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HomeMy WebLinkAboutsW3170305_Add Info Request_20170404Energy, Mineral & Land Resources ENVIRONMENTAL OUALITY April 4, 2017 Mr. Patrick Murphy, PE R. Joe Harris & Associates, Inc. 127 Ben Casey Dr., Ste. 101 Fort Mill, SC 29708 Subject: Request for Additional Information Stormwater Permit No. SW3170305 Larkin Multi -Family Development Iredell County Dear Mr. Murphy: ROY COOPER Governor MICHAEL S. REGAN Secretary TRACY DAVIS Director The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater Management Permit Application for the subject project on March 27, 2017. A preliminary review of that information has determined that the application is not complete. The following information is needed to continue the stormwater review: 1. All SCMs must comply with all MDC in 15A NCAC 02H.1000 and the latest SCM Design Manual. 2. The person signing the application and O&M agreement must be an officer of the corporation listed on the NC Sec. of State's website. Or provide a signed letter from one the officers listed giving Michael Foess signature authority. 3. The rules require the runoff from all BUA to be treated. As currently proposed, approximately 20% of the roof areas is not being treated in a SCM. Evaluate adding piping and/or swales to capture the rear roof areas on lots 2, 3, 14-17, 19, 20, and 25-29. 4. Where does the roadside ditch along Amity Hill Road, where the wet pond discharges, drain to? Does it drain to Third Creek, or Duck Creek to the south? 5. Provide signed and notarized O&M Agreements for the SCMs (General MDC 11). The new O&M EZ form is available on our website: https:Hdeq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land- permit-,guidance/stormwater-bmp-manual Nothing Compares, SState of North Carolina I Environmental Quality I Energy, Mineral and Land Resources 512 N. Salisbury Street 11612 Mail Service Center Raleigh, North Carolina 27699-1612 919 707 9200 6. Please consider using the discrete SCS method or Simple Method for calculating the WQV. Using composite CN will yield an artificially lower volume. General MDC 1 requires a sufficient sized SCM. See also Part B of the SCM Manual https://deq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land- permit-guidance/stormwater-bmp-manual 7. The DA and BUA is not consistently shown between SWU-101, Sht. Post DA, and the supplement forms. Revise so all are consistent. 8. Note there are new supplement forms using Supplement EZ found on our website: https:Hdeq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land- permit-guidance/stormwater-bmp-manual 9. All 3 SCMs: a. The CN is not consistent between Slit. Post DA and the calcs. b. Provide supporting calcs. for the WQV based on the 1" design rainfall depth. (General MDC 1) c. Extend the SCM easements to the nearest public RoW. (General MDC 8) 10. Wet Pond #100: a. Provide supporting calcs. for the surface area using SADA tables or HRT method in MDC 1 b. Provide supporting calcs. for the main pool depth using option 1 or 2 in MDC3 c. Provide supporting calcs. for the forebay size (MDC 5) d. Provide supporting calcs. demonstrating the WQV draws down in 2-5 days (MDC 7) e. Add contours to Slit. BMP -2 to show the actual excavated depth for the sediment storage. Also add the elevation to the profile of the bottom of the sediment storage. 11. Both Sand Filters: a. Provide a soils report for the SHWT elevation for each sand filter. This must be based on an in-situ soils evaluation. (MDC 1) b. Provide a mechanism to evenly distribute flow over the sand surface (MDC 5) c. Specify on Slits. BMP -4 and BMP -5 that ASTM C33 or equivalent sand must be used (MDC 6) d. Revise the stage storage tables to show the cumulative volume at the design WQV elevation. e. Revise the stage storage tables to breakdown the areas, stage, and volumes for each the sediment chambers and the sand chambers. 12. Sand Filter #200: a. Open sand filters require 2' of separation from SHWT elevation to the bottom of the sand layer (MDC 1). The supplement form states there is negative separation. b. The elevations are not consistent between the supplement form and the plans. Nothing Compares—.__. State of North Carolina Environmental Quality Energy, Mineral and land Resources 512N. Salisbury Street 1612 Mail Service Center Raleigh, North Carolina 27699-1612 919 707 9200 Please note that this request for additional information is in response to a preliminary review. The requested information should be received by this Office prior to April 27, 2017, or the application will be returned as incomplete. The return of a project will necessitate resubmittal of all required items, including the application fee. If you need additional time to submit the information, please submit your request for a time extension to the Division at the contact below. The request must indicate the date by which you expect to submit the required information. The Division is allowed 90 days from the receipt of a completed application to issue the permit. The construction of any impervious surfaces, other than a construction entrance under an approved Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject to enforcement action pursuant to NCGS 143-215.6A. Please reference the State assigned project number SW3170305 on all correspondence. If you have any questions concerning this matter please feel free to contact me at Robert.Pattersongncdenr.gov or (919) 807-6369. Sincerely, P 2�� Robert D. Patterson, PE Stormwater Engineer Stormwater Permitting Program ec: Mooresville Regional Office Michael Foess — Dependable Development, Inc. Nothing Compares --,-,,- State of North Carolina Environmental Quality Energy, Mineral and land Resources 512N. Salisbury Street 1612 Mail Service Center Raleigh, North Carolina 27699-1612 919 707 9200