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Home My WebLink AboutSW6091006_401 Certification Application_20100108Permit (to be provided by DWQ) O�O� W A TF,9OG y ® STORMWATER MANAGEMENT PERMIT APPLICATION FORM o WDENR 401 CERTIFICATION APPLICATION FORM INFILTRATION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information. Project Name Fort Bragg - Indoor Rifle Range Contact Person Bryan M. Dick, PE, PH Phone Number 919-854-6252 Date 5/14/2009 Drainage Area Number 1 Site Characteristics Drainage area 70,825.00 ftz Impervious area 39,853.00 ftz Percent impervious 0.56 % Design rainfall depth 1.00 in Peak Flow Calculations 1-yr, 24-hr rainfall depth 3.20 in 1-yr, 24-hr intensity 0.90 in/hr Pre -development 1-yr, 24-hr discharge 0.20 ft3/sec Post -development 1-yr, 24-hr discharge 0.00 ft3/sec Pre/Post 1-yr, 24-hr peak flow control -0.20 ft3/sec Storage Volume: Non -SA Waters Minimum design volume required 3,284.00 ft3 Design volume provided 8,934.00 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 Blaney Infiltration rate 19.10 inlhr SHWT elevation 297.00 fmsl Basin Design Parameters Drawdown time 0.19 days OK Basin side slopes 3.00 :1 OK Basin bottom elevation 310.40 fmsl OK Storage elevation 304.30 fmsl Storage Surface Area 4,241.00 ft' Top elevation 305.00 fmsl Basin Bottom Dimensions Basin length 96.00 ft Basin width 20.00 ft Bottom Surface Area 1,920.00 ft' Form SW401-Infiltration Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2 Permit (to be provided by DWQ) Additional Information Maximum runoff to each inlet to the basin? Length of vegetative filter for overflow Distance to structure Distance from surface waters Distance from water supply well(s) Separation from impervious soil layer Naturally occuring soil above shwt Bottom covered with 4-in of clean sand? Proposed drainage easement provided? Capures all runoff at ultimate build -out? Bypass provided for larger storms? Pretreatment device provided 0.90 ac-in OK NA ft OK 70.00 ft OK 75.00 ft OK NA ft OK NA ft OK 5.00 ft OK Y (Y or N) OK NA (Y or N) OK Y (Y or N) OK N (Y or N) Must provide bypass for larger flows N Form SW401-InfiRration Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2 Permit No. (to be provided by DWQ) 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. If a requirement has not been met, attach justification. Page/ Plan Initials Sheet No. c i 03 1. Plans (1" 50' or larger) of the entire site showing: Design at ultimate build -out, Off -site drainage (if applicable), Delineated drainage basins (include Rational C coefficient per basin), Basin dimensions, Pretreatment system, High flow bypass system, Maintenance access, Proposed drainage easement and public right of way (ROW), Overflow device, and Boundaries of drainage easement. 2. Partial plan (1" = 30' or larger) and details for the infiltration basin showing: Bypass structure, Maintenance access, Basin bottom dimensions, Basin cross-section with benchmark for sediment cleanout, Flow distribution detail for inflow, Vegetated filter, and Pretreatment device. 3. Section view of the infiltration basin (1" = 20' or larger) showing: Pretreatment and treatment areas, and Inlet and outlet structures. L ! a AA19 4. A table of elevations, areas, incremental volumes & accumulated volumes to verify the volume provided. AT AAtftV 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 /1 investigation request form. County soil maps are not an acceptable source of soils information. /50% C1 a 6. A construction sequence that shows how the infitlration basin will be protected from sediment until the entire drainage area is stabilized. �� 7. The supporting calculations. 44 OT171 r-4w_o 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. WX 9. A copy of the deed restrictions (if required). Form SW401-Infiltration Basin-Rev.4 Page 1 of 1 Part III. Required Items Checklist, Page 1 of 1 Permit (to be provided by DWQ) �s ACRA STORMWATER MANAGEMENT PERMIT APPLICATION FORM o NC®ENR 401 CERTIFICATION APPLICATION FORM INFILTRATION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information. P„ROJECT INFORMATION.,,, '<<�.< _.- ,...''t3wk,Y=... a,,cx,Ftn i.c:•=.a.xk.iw'i'�p..,, ,r<'.r..,rr «'..-r.._:. d.. .,-.r"., `.�.,'a a�.r.,x_'*`-F'?_L+s^2y 3.,; _c-.`•xr Project Name Fort Bragg - Indoor Rifle Range Contact Person Bryan M. Dick, PE, PH Phone Number 919-854-6252 Date 1/5/2010 Drainage Area Number 1 III "DESIGNINF.ORMA_TIONP',' A - •- - Site Characteristics Drainage area 70,825.00 ftz Impervious area 39,853.00 ft2 Percent impervious 0.56 % Design rainfall depth 1.00 in Peak Flow Calculations 1-yr, 24-hr rainfall depth 1-yr, 24-hr intensity Pre -development 1-yr, 24-hr discharge Post -development 1-yr, 24-hr discharge Pre/Post 1-yr, 24-hr peak flow control • x:. -Storage Volume: Non, SA Waters Minimum design volume required Design volume provided as Storage Volume: SA Waters 1.5" runoff volume Pre -development 1-yr, 24-hr runoff volume Post -development 1-yr, 24-hr runoff volume Minimum required volume Volume provided Soils Report Summary Soil type Infiltration rate SHWT elevation. Basin Design Parameters Drawdown time Basin side slopes Basin bottom elevation Storage elevation Storage Surface Area Top elevation Basin Bottom Dimensions Basin length Basin width Bottom Surface Area 3.20 in 0.90 in/hr 0.20 ft3/sec 0.00 ft3/sec -0.20 ft3/sec 3,284.00 ft3 8,934.00 ft3 Blaney 19.10 in/hr 297.00 fmsl OK for non -SA waters 0.19 days OK 3.00 :1 OK 301.40 fmsl OK 304.30. fmsl 4,241.00 ft 305.00 fmsl 96.00 It 20.00 ft 1,920.00 ft Form SW401-Infiltration Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2 Permit (to be provided by DWQ) Additional Information Maximum runoff to each inlet to the basin? Length of vegetative filter for overflow Distance to structure Distance from surface waters Distance from water supply well(s) Separation from impervious soil layer Naturally occuring soil above shwt Bottom covered with 4-in of clean sand? Proposed drainage easement provided? Capures all runoff at ultimate build -out? Bypass provided for larger storms? Pretreatment device provided 0.90 ac-in NA ft 70.00 ft 75.00 ft NA ft NA ft 5.00 ft Y (Y or N) NA (Y or N) Y (Y or N) N (Y or N) OK OK OK OK OK OK OK OK OK OK Must provide bypass for larger flows Form SW401-Infiltration Basin-Rev.4 Parts 1. & II. Design Summary, Page 2 of 2 112454 Bragg Gun Range - Infiltration Basin 1 Drainge Area (Sf) 70825 Imp Area (sf) 39853 (A) Drainage Area'(Ac) 1.626 (IA) Imp Fraction 0.56> (RD)Rainfall Depth Per State SWP(in)` 1 Designed By: BMD Date: 1/5/2010 Step 1: Determine Runoff Volume Simple Method a. Rv = .OS + .9(I A) = Rv (post) = .05+.9'.56 = 0.56 Rv (pre) = .05+.9.0 = 0.05 b V=3630xRoxR, 7XA] Post V=3630'1.0"0.56 `1.626 V (Post) = 3284 cf Min. Treatment Vol = 3284 cf Treatment Vol in Ac-in 0.90 ac-in Step 2: Determine Surface Area- Min. lRequired Volume for 2.5X to Not Bypass or Filter 8210 cf (K),Infiltration Rate'(in/hr) 12.26 'Half the K value from the Soils Report (T)'Ihtended Days toinfilttate (days) 2 a. A - V = A=3799/(2`(5.66"2)) 2*(K *T) Step 3. Determine Dimensions Basin Volume Depth to Exist grount to SHWT (ft) 5.00 -From soils report Existing Ground Elevation 302.00 Elevation at Soil Boring Design Storage Elevation 304.30 Bottom Elevation 301.40 Overflow Weir Elevation 304.30 Basin Inlet Elevation 301.40 Top of Berm Elevation 305.00 Max Excavation Depth 3.00 299.00 ft. elev. using site 3 Storage Depth 2.90 Surface Area Required (Avg of Top and Bottom SA) Top Width @ Storage Elev 37.4 Top Length @ Storage Elev Bottom Width 20 Bottom Length 4. Calculation of Volumetric Flow Rate of Infiltration and Drawdown 0 from infiltration: 'Q is actually the Darcian Flow Rate Q=A•(K)• Conversion=cfs ExampleCalculatiaz of Q: SurfaceArea=3184sf (K)=2.42in1 hr 2.42in 1 ft lhr 3184 sf =0.18 cfs hr 12in 3600s Example Calculation: Q = 0.18cfs V = 3184cf 3 V _ T 3184 ft is lhr = 2 lhrs = .049days Q 1 0.18 ft3 3600s Min SA of Basin = 67.0 sf 2.90 2 Target Area 0 sf 113.4 Surface Area Storage = 4241 sf 96.0 Surface Area Bottom = 1920 sf Avg Surface Area = 3081 sf Volume of Basin (Depth"SA) = 8934 cf Exceed Required Volume by 2.72 X Area (sf) (K) in/hr 0 (infiltration) = 0.54 cfs 1920 12.255 Drawdown Time for Design Vol Volume cf Q Hours Days 8934 0.54 4.6 1 0.19