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Home My WebLink AboutSW3240502_Supplement-EZ Form_20240606 (4) Permit No. (to be provided by DWQ) O� WA1-9�G ®v_ STORMWATER MANAGEMENT PERMIT APPLICATION FORM O T NCDENR 401 CERTIFICATION APPLICATION FORM INFILTRATION BASIN SUPPLEMENT This form must be filled out,printed and submitted. The Required Items Checklist(Part Ill)must be printed,filled out and submitted along with all of the required information. I. PROJECT INFORMATION Project Name Sage at Marvin Contact Person Brandon Maxwell Phone Number 704-777-8888 Date 4/22/2024 Drainage Area Number Proposed Watershed 1A II. DESIGN INFORMATION Site Characteristics Drainage area 308,709.72 ft2 Impervious area 118,174.08 ft2 Percent impervious 38.28 % Design rainfall depth 2.93 in Peak Flow Calculations 1-yr,24-hr rainfall depth 2.93 in 1-yr,24-hr intensity 0.12 in/hr Pre-development 1-yr,24-hr discharge 12.94 ft3/sec Post-development 1-yr,24-hr discharge 8.67 ft3/sec Pre/Post 1-yr,24-hr peak flow control -4.27 ft3/sec Storage Volume:Non-SA Waters Minimum design volume required 13,199.00 ft3 Design volume provided 15,481.00 ft3 OK for non-SA waters Storage Volume: SA Waters 1.5"runoff volume ft3 Pre-development 1-yr,24-hr runoff volume ft3 Post-development 1-yr,24-hr runoff volume ft3 Minimum required volume ft3 Volume provided ft3 Soils Report Summary Soil type K-4 Sand Infiltration rate 5.00 in/hr SHWT elevation 570.00 fmsl Basin Design Parameters Drawdown time 2.33 days OK Basin side slopes 3.00 :1 OK Basin bottom elevation 572.00 fmsl OK Storage elevation 576.90 fmsl Storage Surface Area 5,212.00 ft2 Top elevation 578.00 fmsl Basin Bottom Dimensions Basin length 104.00 ft Basin width 20.00 ft Bottom Surface Area 1,326.00 ft2 Form SW401-Infiltration Basin-Rev.5 11Apr2011 Parts I.&II.Design Summary 1,Page 1 of 5 Permit No. (to be provided by DWQ) Additional Information Maximum runoff to each inlet to the basin? 6.04 ac-in Maximum of 2 acre-inches allowed Length of vegetative filter for overflow 0.00 ft Filter is too short,must be>30-ft Distance to structure 41.00 ft OK Distance from surface waters 194.00 ft OK Distance from water supply well(s) 5,489.00 ft OK Separation from impervious soil layer 2.00 ft OK Naturally occuring soil above shwt 0.00 ft Minimum of atleast 1-ft of naturally occuring soil above shwt Bottom covered with 4-in of clean sand? Y (Y or N) OK Proposed drainage easement provided? Y (Y or N) OK Capures all runoff at ultimate build-out? Y (Y or N) OK Bypass provided for larger storms? N (Y or N) Must provide bypass for larger flows Pretreatment device provided Grassed Swales Form SW401-Infiltration Basin-Rev.5 11Apr2011 Parts I.&II.Design Summary 1,Page 2 of 5 Permit No. (to be provided by DWQ) O� WA1-9�G An STORMWATER MANAGEMENT PERMIT APPLICATION FORM O T NCDENR 401 CERTIFICATION APPLICATION FORM INFILTRATION BASIN SUPPLEMENT This form must be filled out,printed and submitted. The Required Items Checklist(Part Ill)must be printed,filled out and submitted along with all of the required information. I. PROJECT INFORMATION Project Name Sage at Marvin Contact Person Brandon Maxwell Phone Number 704-777-8888 Date 4/22/2024 Drainage Area Number Proposed Watershed 2A II. DESIGN INFORMATION 1111111 Site Characteristics Drainage area 1,019,608.92 ft2 Impervious area 266,219.89 ft2 Percent impervious 26.11 % Design rainfall depth 2.93 in Peak Flow Calculations 1-yr,24-hr rainfall depth 2.93 in 1-yr,24-hr intensity 0.12 in/hr Pre-development 1-yr,24-hr discharge 9.16 ft3/sec Post-development 1-yr,24-hr discharge 8.50 ft3/sec Pre/Post 1-yr,24-hr peak flow control -0.66 ft3/sec Storage Volume:Non-SA Waters Minimum design volume required 49,963.00 ft3 Design volume provided 51,726.00 ft3 OK for non-SA waters Storage Volume: SA Waters 1.5"runoff volume ft3 Pre-development 1-yr,24-hr runoff volume ft3 Post-development 1-yr,24-hr runoff volume ft3 Minimum required volume ft3 Volume provided ft3 Soils Report Summary Soil type K-4 Sand Infiltration rate 5.00 in/hr SHWT elevation 573.00 fmsl Basin Design Parameters Drawdown time 2.46 days OK Basin side slopes 3.00 :1 OK Basin bottom elevation 576.00 fmsl OK Storage elevation 583.00 fmsl Storage Surface Area 11,049.00 ft2 Top elevation 584.50 fmsl Basin Bottom Dimensions Basin length 84.00 ft Basin width 54.00 ft Bottom Surface Area 4,180.00 ft2 Form SW401-Infiltration Basin-Rev.5 11Apr2011 Parts I.&II.Design Summary 2,Page 3 of 5 Permit No. (to be provided by DWQ) Additional Information Maximum runoff to each inlet to the basin? 12.17 ac-in Maximum of 2 acre-inches allowed Length of vegetative filter for overflow 0.00 ft Filter is too short,must be>30-ft Distance to structure 50.00 ft OK Distance from surface waters 401.00 ft OK Distance from water supply well(s) 5,177.00 ft OK Separation from impervious soil layer N/A ft OK Naturally occuring soil above shwt 0.00 ft Minimum of atleast 1-ft of naturally occuring soil above shwt Bottom covered with 4-in of clean sand? Y (Y or N) OK Proposed drainage easement provided? Y (Y or N) OK Capures all runoff at ultimate build-out? Y (Y or N) OK Bypass provided for larger storms? N (Y or N) Must provide bypass for larger flows Pretreatment device provided Grassed Swales Form SW401-Infiltration Basin-Rev.5 11Apr2011 Parts I.&II.Design Summary 2,Page 4 of 5 Permit No. (to be provided by DWQ) III. REQUIRED ITEMS CHECKLIST Please indicate the page or plan sheet numbers where the supporting documentation can be found.An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project.Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent,the agent may initial below.lf a requirement has not been met,attach justification. Pagel Plan Initials Sheet No. JR CS1OO- 1. Plans(1"-50'or larger)of the entire site showing: CS1O2, -Design at ultimate build-out, CG1OO- -Off-site drainage(if applicable), CG-102, -Delineated drainage basins(include Rational C coefficient per basin), CS5O1- -Basin dimensions, CS5O6 -Pretreatment system, -High flow bypass system, -Maintenance access, -Proposed drainage easement and public right of way(ROW), -Overflow device,and -Boundaries of drainage easement. JR CS1OO- 2. Partial plan(1"=30'or larger)and details for the infiltration basin showing: CS1O2, -Bypass structure, CGI 00- -Maintenance access, CG-102, -Basin bottom dimensions, CS5O1- -Basin cross-section with benchmark for sediment cleanout, CS5O6 -Flow distribution detail for inflow, -Vegetated filter,and -Pretreatment device. JR CS5O1- 3. Section view of the infiltration basin(1"=20'or larger)showing: CS5O6 -Pretreatment and treatment areas,and -Inlet and outlet structures. JR * 4. A table of elevations,areas,incremental volumes&accumulated volumes to verify the volume provided. JR * 5. A soils report that is based upon an actual field investigation,soil borings,and infiltration tests. The results of the soils report must be verified in the field by DWQ,by completing&submitting the soils investigation request form. County soil maps are not an acceptable source of soils information. JR GI1O1 6. A construction sequence that shows how the infitlration basin will be protected from sediment until the entire drainage area is stabilized. JR * 7. The supporting calculations. JR * 8. A copy of the signed and notarized operation and maintenance(O&M)agreement. JR * 9. A copy of the deed restrictions(if required). * Please see this submission package for required information. Form SW401-Infiltration Basin-Rev.4 Page 5 of 5 Part III.Required Items Checklist,Page 5 of 5