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Home My WebLink AboutSW5240301_Response To Comments_20240703 JK JoynerKeeny Planning,Surveying&Engineering July 3,2024 DEMLR Stormwater Program Attn: Brianna Holland 512 N. Salisbury Street, Office 625Y Raleigh NC 27604 Reference: Request for Additional Information—Stormwater Permit No. SW5240301 Juniper Ridge Subdivision—Low Density—Nash County Ms. Holland: Please consider our response to comments from your letter dated June 20th,2024,which have been addressed as follows in bold blue text: 1. Application Section IV, 10 a. For Low Density,the Total Drainage Area proposed is comprised only of an Onsite Drainage Area Component,which is the Total Project Area listed in Section IV.7. Off-site Drainage Area is not included in low-density projects. Revise Supplement-EZ Drainage Areas Page for consistency. RESPONSE: All values for areas were revisited in more detail for this project. Adjustments were made as needed. No offsite area was included on any of the forms. Note that DA2 is the area that is within the overall property,but outside of the State Permit area. This area is regulated by Nash County as Water Supply Watershed,which meets the Phase II requirements. Revisions were made to the area values in the following sections of the application: IV.4,IV.6,IV.7,IV.8, IV.10. See PDF"Application Page 3" Areas on the Supplement EZ form were also updated with the same information. b. On-site Buildings/Lots. Revise to match the BUA allocated by the deed restrictions. This will cause revisions to be needed in the total BUA,percent impervious, etc. 15A NCAC 2H .1003(7). RESPONSE: Revised to match the BUA allocated by deed restrictions per Supplement EZ attachment (referenced in Cover Page#22 additional information). Calculations for areas of lots partially in each DA are shown on the attached table"OldSmithfieldBUAlotsV2". Post Office Box 7533. 1051 N.Winstead Ave.• Rocky Mount•North Carolina•27804-7533 252-977-3124(office)•www.joynerkeeny.com•252-985-6026(fax) JK JoynerKeeny Planning,Surveying&Engineering 2. Clearly identify and delineate the top of banks of the stream and associated vegetated setback in the main set of plans(Section VI, 8h). If it is not possible to delineate the backs of the surface water(as would be the case for a narrow stream),please show the centerline of the surface water and provide a callout listing the surface area of that surface water that is within the project boundary.Note that the surface area of the surface water is the area between the top of the banks and of the streams. Ensure the vegetated setback is measured horizontally from the top of bank of each side of streams for all perennial and intermittent surface waters within and adjacent to the site. 15A NCAC 02H. .1017 (10), 15A NCAC 02H.1003(4)(a), 15A NCAC 02H.1042(2)(g)(iii). Ensure the surface water area is revised across the package accordingly. RESPONSE: Revised as requested; please see sheet C-03 Layout and C-04A Post-Construction Stormwater&Drainage Areas Plan. The top of bank was delineated by the wetland consultants. Corrected surface water area IV, 6& Supplement-EZ Cover Page item 4. 3. Delineate drainage areas to the swales on the main set of plans. 15A NCAC 02.1042(2)(a)(iv), .1003. RESPONSE: Drainage areas and swale callouts are shown on sheet C-04A Post-Construction Stormwater &Drainage Areas Plan 4. Supplement-EZ, Low Density Page, Line 4-revise this item to reflect both 3:1 and 4:1 slopes. This may need to be overwritten in PDF, or it can be noted in the additional information in Line 15. RESPONSE: Low Density form Line 4 revised to reflect both 3:1 and 4:1 slopes 5. If the check dams at the outlets are intended to be permanent and protect the outlets of the site form erosion during the 10-year storm as required per 15A NCAC 02H.1003(5),please provide engineering calculations demonstrating that the each of the outlets will not cause erosion down slope of the discharge point during the peak flow from the 10-year storm event. Provide sizing specifications that correspond to the calculations on the plans. RESPONSE: Check dams are temporary measures meant to help prevent erosion until vegetation is established. Check dams are not shown on C-04A Post-Construction Stormwater&Drainage Areas Plan. Post Office Box 7533. 1051 N.Winstead Ave.• Rocky Mount•North Carolina•27804-7533 252-977-3124(office)•www.joynerkeeny.com•252-985-6026(fax) JK JoynerKeeny Planning,Surveying&Engineering 6. Please clarify the Manning's Roughness Coefficient that is used for the provided swale calculations and ensure the permanent conditions are shown in the Supplement-EZ Swale Table. Demonstrate that the flow/velocity of the 10-year storm will not erode the permanent liner 15A NCAC 02H.1003(2)(ii). RESPONSE: The value of the Manning's Roughness Coefficient was taken from NCDOT Drainage Studies Guideline, Chapter 7.4.3.1,Table 3. The 0.4 value is preferred by NCDOT for this type of development. Instead of calculating a composite c-value for each drainage area,the 0.4 c value is used for all drainage areas within this single-family residential project to match NCDOT guidelines. The BUA and pervious area of each individual swale drainage area were not needed and are noted as"n/a" on the Supplement-EZ Low Density page. The "JuniperRidgeDitchCalc"spreadsheet demonstrates that the calculated shear/velocity of the 10-year storm runoff does not exceed the permissible shear/velocity of the proposed permanent liner. 7. Note that this review is only for the permanent post construction stormwater conditions,temporary erosion control measures shown in plans and calculations are not reviewed as part of this permit and will be discarded from the permitted set. RESPONSE: Noted. Section IV.1 was revised to remove references to temporary measures. Please see C- 04A Post-Construction Stormwater&Drainage Areas Plan for review. 8. Please provide a Response to Comments letter indicating, in a point-by-point manner,how each of the above comments has been addressed. This item is required per 15A NCAC 02H .1042(3)(b). RESPONSE: Response letter to comments provided herein. Post Office Box 7533. 1051 N.Winstead Ave.• Rocky Mount•North Carolina•27804-7533 252-977-3124(office)•www.joynerkeeny.com•252-985-6026(fax) JK JoynerKeeny Planning,Surveying&Engineering 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. a. PDFs must be uploaded using form at: https://edocs.deq.nc.gov/Forms/SW-Supplemental-Upload b. Hard copies must be mailed or delivered to the following address: i. For Fed Ex/UPS: Brianna Holland 512 N. Salisbury Street, Office 625Y Raleigh NC 27604 ii. For USPS Brianna Holland 1612 Mail Service Center Raliegh,NC 27699-1612 iii. Hand Delivery Please reach out to me prior to hand delivering a submission to make sure that I(or someone else in my group)will be able to receive the submission. Do not leave the package in the foyer with the security guard. NOTE: Hard copies should not be sent to a Regional Office. Doing so will delay the review process and the submission package may be lost while being sent from the Regional Office to me in the Central Office. RESPONSE: Submission provided per instructions. Sincerely, Joyner Keeny, PLLC SAA.14,-aft" Briana Eddy Civil Engineering Project Manager Project#230576A Enclosures cc: Blair Alford Nick Rightmyer,PE Grey Berry Fletcher Beasley Post Office Box 7533. 1051 N.Winstead Ave.• Rocky Mount•North Carolina•27804-7533 252-977-3124(office)•www.joynerkeeny.com•252-985-6026(fax)