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Home My WebLink AboutSW6100804_Application Form_20220611 (2) Permit1 o- w by_ D nst utlur. . -. . ;._ ••. •• these documents i required by iII (or water .. . --tit. North Carolina rules require that the stormwi . . system designer inspect during construction; fe'. ,4 conformity with the Irm plans and specs; and certiT,v.fince with the stormwater rules. ( 15P NC A,. ::,1-1 . t 08 (j ) ) Permit # 6./6 L 0 OVO 9 [ ate 0 v4 by - 1 - . __._ NC Division cif t r7luality ATCIFIliA anew. kly_pC,Evyt SrAre,_ac,viciitin f:lts]. V p_t_ 0. , iO4-‘. .d* . + � : [o/ $CDENRPP�I 1�1 FORM STRIWATER MANAGEMENT PERMIT A . - 401 CERTIFICATION APPLICATION FORM . 11111111r— 1— WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Re wired Items Checklist (Part lit must be printed, Mr�led out and submitted akin with all of the required i,nforTrration. h-k 1. PROJECT INFORMATION ... _ . : _ .. - - --- . . -- ---- .............�-�----� --• - � - � lac al Summit Contact person Project name Jeffrey noes, PE Phone number ( 10)48 --4 00 Date 811112010 Drainage area number 1 .{ III. DESIGN INFORMATION Site Characteristics y Drainage area _ _ 1,568,160 ft2 ; 779,288 ft2 NUV 8 ioie Impervious area, post-development Ill °O impervious - 49.69 Flo Design rainfall depth r 1.0 in OWQ pi Storage Volume: Non-SA Waters a nor4: u33 f'W il#wii trims i v 4 lum I Ie i Uii i 1111 Volume provided 67,707 a OK, volume provided is equal to or in excess of volume required. • Storage Volurne' SA Waters 1,5" runoff volume ft Pre-development 1-yr, 4-hr runoff -. Post-development 1-yr, 24-hr runoff - ft Minimum v lur ecequfr d 113 ft3 twilling! it1iIng! Volume provided _ t-I" i AR l to dtr Peak Flow Calculations � � t 4 the prelpo l control of the 1 yr 4hr stormpeak flow required? or N) 1-yr, 24-hr rainfall depth - - 3 0 in 0.20 (witless) • z / i vi:-1.- l Rational post-development atyanati pre-development �LI 1 - ai t.ft _ O,6 (ur ns)) M (�.1 3 ir>f OK : 4-hr stt rm tr 1 fse Rainfall intensity; 1-yr, �- - • Pm-development 1-err, 4-l�T peak flow 0. 0 C �"0 '•'-rtig:ttvih%e , , Post-development 1-yr, 4-hrp kc flow 1,20 '1i . S� , prelPoct 1 yr, 4-hr peals flow cohol olliCiii ; 1-1% - la Elevation — Temporary pool elevation — 432.00 frnsl • permanent pool elevation 431_00 frr st H T elevation (approx. at the perm. pool ele+ tion) _ 425_42 fmsl Top of 10ft vegetated she elevation 431_50 frnsl Bottom of 10fk vegetated shelf elevation 430,50 f nsi Data not needed for calculation option #1, but OK if provided. Sediment cleanout, top elevation (bottom of pond} 428.00 f sl Sediment cteanoot, bottom elevation _4 7,00 frnsi Data not needed for calculation option #1, but OK if provided. �Sediment storage provided i.00 ft - is there additional volume stored above the state-required temp. pool? N eir or I } Elevation of the top of the additional volume 432,0 trnsl o FormForrn sw401- +et Detention 9asir-Rev_8-9f17 3 P i. & II_ De igr r rna .YI, -age 1or 1 i. ,,, - Er me basin must be drained for an emergency or to perform maintenance, the flushing of sediment through the emergency drain should be minimized to the WrIiiiii Q i rri i,-L Q.A.,-1- -- -- - ,.1 - w ik 1 0 '0 11 Pit f I go be provided b Qi 0 f1s DESIGN ► ON Surface Areas F Area, temporary pool 70,305 f . Area REQUIRED, permanent pool ,63� ff SAIDA ratio2 uni�e s Area PROVIDED, permanent pool, A , , 77 OK Area, bottom of 10ft vegetated shelf, s, 55, ft' 4 Area, sediment cleanout, top elevation (bottom of pond), A i — 50,196ft' _ Volumes Volume, temporary pool ., _ 67,707 ft3 OK 1 ._ Volume, permanent pool. V 6 7 - . Volume, forebay (sum of forebays if more than one forebay) 33,939 ft3 Forebay % of permanent pool volume 20.7% % OK SAIDA Table Data Design TSS removal . II Coastal SAIDA Table Used? _ Y or tw+lountaarrfPiedt ont AfDA Table Used? N) (Y or N) SAIDA ratio 3.4 (unitless) IFir Average depth (used in SAIDA table): Calculation option 't used? See Figure _ b (Y or N) Use only one calculation option. Volume, permanent pool, V�,et,,, , 163,571 ft Area provided, permanent pool, App m per, 63,277 ft2 Average depth calculated ft Need 3 ft rein, Average depth used in SNIDA, dam, (Round to nearest 0.5ft) ft Calculation option 2 used? (See Figure 1O- b) ' Y (Y or N) Use only one calculation option, Area provided, permanent pool, Ape,Isoci 63,277 f Area, bottom of 10ft vegetated shelf, Ahlitiali,11 unijOEC n li Area, sediment cleanout, top elevation (bottom of pond), A 50,196 ft2 "Depth" (distal b/w bottom of 10#t shelf and top of sediment) 2.50 ft Average depth calculated _ 3, 0 ft OK Average depth used in AfDA, d ,,, (Round to nearest 0. ft) 3,5 ft OK Drawdown Calculations t w t r u f t 3rawdown through orifice? - Y or N) '' ' 1 CAI?, fie Diameter o orifice ( circular) . .50 in 40 41 1..4 ,.....-., r.5 c.,61 z ) :: 1 •�, Ares of orifice non r ular) in Coefficient of discharge (CO � IMP 1 Driving head( f , ftrikettite-s r Drawwdown through w N (Y INN) i tolo '• Weir type (witless) Coefficient of discharge (unitless) • ��-,e 1 '.1- , _ Length of elf - ft . *�% . Driving head (#-1 f ' ` _ f Pre-development 1..yr, 244w peak flow --- .. 0,39.ft3Isec Post-development 1 yr, 4 peak flow 120 lt3fsec Storage volume discharge rate (through discharge orifice or weir) 0.10 fk3lsec 5 Storage volume drawdown time 4.07 days OK draws down in - days. Additional Information Vegetated side slopes 3 :1 OK Vegetated shell slope _ . 10 :1 OK Vegetated shelf width — - 10.0 ft OK Length of fowpath to width ratio _ 3 :1 OK Length to width ratio 2,5 :1 OK Trash rack for overflow &orifice? ' T -.ef or ) OK Freeboard provided 19 ft OK Vegetated filter provided? N or N) Insufficient. Vegetated Ater required. Recorded drainage easement provided? ,- Y --rir or N) OK Capures all runoff at ultimate build-out? Y (lf or N) OK Drain mechanism for maintenance or emergendes : Piurnp out - - — — _ Form itei-Wet Detention Basin-Re+r-8-?17# 9 Parts i.& II. Design Summary, Page 2 of 2 Permit No, Ski I 5V (to be provided by WQ) KQUIRED ITEMS CHECKLIaL:- F. 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, Pagel Plan Initials Sheet No. 314)15 1 , Plans 1' - 0' 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. 1_13 2. Partial plan (1" 0' or larger) and details fort the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, ` Forebay and main pond with hardened emergency spillway, - Basin cross-section, Vegetation specification for planting shelf, and - Filter strip. ' � 3. Section view of the wet detention basin 'l" = 0' or larger) showing - Side slopes, :1 or lower, - Pretreatment and treatment areas, and - Inlet and outlet structures. 3/ Li 4, If the basin is used for sediment and erosion control during construction, clean out of the basin is specified on the plans prior to use as a wet detention basin. a Moctlei 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. 4/1? - 7. The supporting calculations. 8. A copy of the signed and notarized operation and maintenance (O&M) agreement, 9. A copy of the deed restrictions (if required), 1 . A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County - --Cf66" soil maps are not an acceptable source of soils information. • Part III. Required items Checklist, Page i of '1 Form W401- et Detention Basin-I ev.8-9117199