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HomeMy WebLinkAboutSW6231204_Response To Comments_20240725 $F4Dsite 'Z ' solutions July 24, 2024 civil engineering I land surveying NCDEQ Division of Water Quality Attn: Brianna Holland 512 N. Salisbury Street Raleigh, NC 27604 RE: Storm water resubmittal, Starz Gas Station (SW6231204), Hoke County, North Carolina Brianna; We received the initial review comments dated March 20, 2024 for the Starz Gas Station.The response to each of the comments is listed below. 1.As designed,this project does not meet the design requirements to be considered as a low- density development. Per 15A NCAC 02H .1003(1)(d) it has been determined that this project has a high-density pocket(For example, if the limit of disturbance was used to calculate the project density, the density for this project would be 45% instead of 6%. If the impervious cover were more spread out over the entire property area,this wouldn't be an issue, but the fact that all of the proposed BUA is concentrated in such a small portion of the property leads it to behave more like a high-density project than a low density project). Per 15A NCAC 02H .1003(2)(b),this project is not designed with the intent to disperse flow. Most all of the runoff from the site is channelized and conveyed via curb &gutter and/or vegetated conveyance.A low-density project would be designed so that most, if not all of the runoff from proposed BUA is allowed to sheet flow across vegetated areas as dispersed flow. Per 15A NCAC 02H .1003(2)(c), piping networks (such as those connecting the catch basins) are not allowed. Pipes are only allowed in low-density projects for unavoidable situations where a swale would not work (such as transporting stormwater underneath a driveway) and in certain unavoidable situations where non-erosively conveying stormwater via a swale is not practical. Please revise the submission so that this project meets all of the low-density requirements or revise the submission so that this project meets all of the high-density requirements. The project drainage has been revised substantially.All of the storm boxes interior to the site have been eliminated and generally the entire site sheet flows to a perimeter ditch and ultimately to a ditch that conveys the water off site. 2. Please ensure consistency throughout the package.The Supplement-EZ states the name of the project as "Faircloth Gas Station,"while Starz Gas Station is listed elsewhere. We have gone through all of the submittals and updated the project name to "Starz Gas Station" on all documents that are editable. The "Faircloth Gas Station"was renamed to "Starz Gas Station". If any references to Faircloth remain please know that Faircloth was the original name and these projects are one and the same. 3. Ensure the contact information provided in the Application is accurate.The contact 409 Chicago Drive, Suite 112, Fayetteville, NC 28306 office 1910-426-6777 fax 1910-426-5777 On time,every time. I www.4Dsitesolutions.com information for Munawar Shahbain of Johnson Mill Shops, LLC is the same as Mubarak Shahbain of Raeford Development Company, LLC. This is the correct contact information.This information listed is the address and phone number for both "Johnson Mill Shops, LLC"and "Raeford Development Company, LLC". 4. Per the USGS Topographic map (clipped below), it appears that surface water is present on site. All surface water that appears on the latest USGS topographic map must be accounted for and depicted on the plans per 15A NCAC 02H .1017 (10). Please do the following: Prior to beginning work on this site we had this issue investigated by Soil & Environmental Consultants, PA.The wetland and surface water information has been added to the plan set. a. Please include the on-site surface water area in Section IV, 6 of the Application.This information should also be included on Line 4 of the Cover Page of the Supplement- EZ Form. a. Added b. Please recalculate the total project are as shown in Section IV, 7 of the Application. This information should also be updated on Line 2 of the Cover Page of the Supplement-EZ Form, on Lines 5 &6 of the Drainage Areas Page of the Supplement- EZ Form, and in the table in Section IV, 10 of the Application. a. Updated c. Please recalculate the project percent impervious area as shown in Section IV, 8. This information should also be updated on Line 18 of the Drainage Areas Page of the Supplement-EZ Form and in the table in Section IV, 10 of the Application. a. Updated d. Provide vegetated setbacks on the plans per 15A NCAC 02H .1017 (10). a. These are shown on Sheet C3.2 5. Please correct the following issues with the Supplement-EZ Form: a. Cover Page: i. Line 7—Per 15A NCAC 02H .1017(10) the minimum required vegetated setback width is 30 ft. Done ii. Lines 8&9—Please revise as needed. Done b. Low Density Page: i. Line 5—The maximum velocity provided here should match the maximum velocity provided on the swale table. Done 6. Curb outlet system requirements must be met at the curb cuts. Refer to 15A NCAC 2H .1003(2)(d)for all requirements. The curbing and curb cuts have been removed from the design. 7. Provide calculations demonstrating that the outlet of pipe for is compliant with 15A 2 NCAC 2H .1003(5). Stormwater outlets shall be designed so that they do not cause erosion downslope of the discharge point during the peak flow from the 10-year storm event as shown by engineering calculations. The revised design has three pipe outlets into the perimeter ditch. Calcs have been provided for each of the dissipaters showing these outlets as stable. 8. Provide calculations demonstrating the riprap associated with the curb cuts is compliant with 15A NCAC 2H .1003 (5). Stormwater outlets shall be designed so that they do not cause erosion downslope of the discharge point during the peak flow from the 10-year storm event as shown by engineering calculations. The curb and curb outlets have been removed from the design. 9. Provide PDFs of all revisions, 2 hardcopies of revised plan sheets, 1 hardcopy of other documents, and a response to comments letter briefly describing how the comments have been addressed. Done I look forward to working with you on this project. If you have any questions or concerns, please contact me at your earliest convenience. Sincerely, 4D Site Solutions, Inc Scott Brown, PE sbrown@4dsitesolutions.com Enclosure 3