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Home My WebLink AboutSW8050313_COMPLIANCE_20050506STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. SW _2(I)5 aaI3 DOC TYPE ❑ CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE COMPLIANCE EVALUATION INSPECTION DOC DATE �LY�SOSfXp YYYYMMDD DETENTION POND ANALYSIS FILE NAME: G:\DATA\WPDATA\WQS\POND1050313.WK1 PROJECT#: SW8 050313 REVIEWER: P.Bartlett PROJECT NAME: Preservation Park A�-1610 Ext. Det. Wetlands DATE: 06-May-05 Receiving Stream: Bradley Creek Class: SC Drainage Basin: Cape Fear Index No. 18-87-24-4-(1) Site Area 3.06 acres Drainage Area square feet Area = 0.95 acres IMPERVIOUS AREAS Rational C Bldgs 10800,00 square feet 0.95 pA &t Streets 4289.00 square feet 0.95 2 Parking/driveways 3491.00 square feet 0.95 feet yr, a square square feet A K*w square feet TOTAL square feet Rational Cc=/ 0.54 SURFACE AREA CALCULATION % IMPERVIOUS 44.90% SA/DA Ratio 3.79% Des. Depth 3 Req. SA 1569 sf TSS: 85 Prov. SA sf VOLUME CALCULATION place a "'I" in the box if Rational is used Rational ?* FOREBAY Des. Storm inches Perm. Pool Volume= 1770 Rv= 0.45 Req. Forebay Volume= 354 Bottom 19 msl Provided Volume= 391.00 Perm. Pool msi Percent= Design Pool 23 rnsl Design SA 2318 sf Req. Volume ... ....... . cf SA @ Prov. Volume 1983 cf Elevation= ORIFICE CALCULATION Avg. Head = 0.49 ft Q2 Area = 0.39 sq. in. Flow Q2, cfs 0.009 cfs Q5 Area = 0.15 sq. in. Flow Q5, cfs 0,004 cfs Orifice Area 0.20 sq. in. No. of Orifices Q= 0.005 cfs Diameter, inches 0;i5 weir H x W in x in Drawdown days COMMENTS Surface Area , Volume and Orifice are within Design Guideline TRIPP ENGINEERING, P.C. 419 Chestnut Street Wilmington, North Carolina 28401 Phone: (910) 763-5100 - FAX: (910) 763-5631 May 4, 2005 NCDENR Division Water Quality 127 Cardinal Drive Wilmington, NC 28405-3845 Attn: Mr. Paul Bartlett Re: Preservation Park SWS 050313 New Hanover County, NC TE 04135 Dear Paul: In response to your correspondence dated March 21, 2005, we offer the following: l . Drainage area to basin is 0.95 acre. Application and supplement have been corrected. 2. A note has been provided about Corps approval of wetland delineation. 3. Coastal Tables have been used for SA/DA of 45% = 3.80. 4. A planting plan by the wetland consultant is enclosed. Please review for approval and contact us with any questions, comments or if you need additional information. Thank you. Sincerely, Tripp Engineering, P.C. Charles D. Cazier, E.I. CDC:dcb Enc. MAY 0 s )a 13 5/4/2005 Prese ZPrk CDC Stormwater Wetlands Calculations 04135 Total Drainage Area s . ft. acres 41.250 0.95 Impervious Area Land Use s . M. acres buddin s 10.800 0.25 asphalt 4,289 0.10 concrete 3,491 0.08 Total 18,580 0.43 Stormwater Calculations: Time of Concentration Hydraulic Length (L) = 250 ft. change in Height (H) = 3 ft. Tc = (Lj !N).soa / 128 - 3.01 min. use 5.00 min. Flow for 10 year, 6 hour Storm (Q1o): QPRE _ (CPRE) x (110) x (Area) 1.71 cfs OpcsT = (CPosT) x (1i0) x (Area) 3.90 cfs oou ocora a uaeacia ror lu year Srorm: CN = (98)(% imp.) + (60)(1-% imp.) = 78 P = 4.80 in, for 10 yr, 6 hr storm S= 10001CN-10 2.82 Depth (D)= [P-(0.2)(S)]2 1 [P+(0.8)(S)] = 2.54 in. Time to Peak Flow; Tp = [(43.5)(0)(Area)) 1 010 posT = 26.84 min. Pocket Wetlands Design Pond Size: Elevation (ft.) 22,00 Surface Area (sq. ft.) 1,646 Permanent Pool Flood Pool 2. 100 2,318 Top of Bank 25.00 3,458 Bottom of Pool 19.00 5 Pond Depth Distribution: Depth Below Permanent Pool Surface Area (sq. ft. High Marsh 0 to 9" 572 Low Marsh 9" TO 18" 572 Open Water > 18" 490 Total Provided Storage Volume: Vol. _ [(Normal pool SA + Flood Pool SA) / 21 x (F.P. elev. - N.P. elev.) 1,982 cu.ft. 04135STATEPONO °k impervious = 0.450 = 45.0°% use 45.0% CPRE= 0.25 CPosT = (% imp.)(.95)+(1-% imp,)(.25) 0.57 110 = 7.23 in/hr i50 = 8,87 in/hr Flow for 50 year, 6 hour Storm (050) OPRE _ (CvRE) x (110) x (Area) = 2.10 cis QposT = (CpasT) x (I10)x (Area) 4.79 cfs Soil Storage Capacity for 50 year Storm: CN = (98)(% imp.) + (60)(1-% imp.) 78 P = 6.42 in. for 50 yr, 6 hr storm S = 10001CN - 10 = 2.82 Depth (D)= [P-(0.2)(S)]21 (P+(0.8)(S)] 3.95 in. Time to Peak Flow: Tp = [(43.5) (D) (Area)] / Q50.PoST 34.00 min. State Surface Area'Re uiroment at normal pooi: SAIDA = 0.0380 Required SA = (SAIDA) x (Total Drainage Area) 1.568 s . ft. State Volume Requirement for Storage of first 1" runoff Rv = .05+,009(Percent Impervious) 0.455 intin Vol. _ (Design Rainfall)(Rv)(Drainage Area) = 1565.38 cu.ft. .��'C,�.CAROC C.)J./,41ESSIp,=9�'L9 r SEAL 17374 4a �i GREGG �� Iflli11O 1 of 2 05 "04'K Y - 5/4/2005 CDC Preservation Park Stormwater Wetlands Calculations 04135 Forebay: Required Volume Vol, = 20% of temporary and permenant storage volume 354 cu. ft, 'Allowable range 22%-16% Outlet Structure Design: Flow for 2-day drawdown: far 1st 1" of stormwater, Q = Provided State Vol. 1 172,800 sec. (2-days) = 0,011 cfs Required Area of Pipe for 2-day drawdown'. A= Q I [Cd x SQRT(2 x g x h)] Cd = 0.6 9 = 32.2 ft./sz In = (F.P. elev.- N.P. elev.) 12 0.5 ft. A = 0.0034 s . ft. Diameter of Pipe for 2-day drawdown: DIA. = SQRT[(A x 4) 1 pi] = 0.0655 ft. = 0.79 in. USE A .5 IN. DIA. PIPE Outlet Structure Check: Using a 4' x 4' Basin, Perimeter L) = 16 ft, Q = CIA C = (% imp.)(.95) + (1-% imp)(25) 0.57 1 = 7.23 in. for a 10 yr. Storm A = 0.95 Acres = 3.90 cfs Q= CwxLxH15 H = (Q / (Cw x L)]" Cw = 3 Peak elevation = flood pool elevation + H = 23.19 ft. Provided Volume Bottom SA = 2 sq. ft. Norma{ Pool SA = 311 sq. ft. Vol. _ [(N.P. SA+ Bottom SA) 121 x (N.P. el. - Bottom el.) 391 cu. ft. Flow for 5-day drawdown: for ist 1" of stormwater, Q = Provided State Vol. 1432,000 sec. (5-days) 0,005 cfs Required Area of Pipe for 5-day drawdown: A= Q! [Cd x SQRT(2 x g x h)] Cd = 0.6 9 = 32.2 ft./s2 h = (F.P. elev. - N.P. elev.) 1 2 0.5 ft. A = 0.0013 s . ft. Diameter of Pipe for 5-day drawdown: DIA. = SQRT[(A x 4) / pi] 0.0414 ft. = 0.50 in. 04135STATEPOND 2 of 2 .,MAR 10,2005 04:17P 9107635631 NOWNR North Carolina Department of Environment and Natural Resources 127 Cardinal Drive Extension, Wilmington. NC 28405 (910)395-3900 FAX (910)350-2004 Request for Express Permit Review FILL-IN all Information below and CHECK required Permit(s). FAX to Cameron Weaver along with a narrative and vicin4 ma of the project locattion. Projects must be submitted by 9:00 A.M. of the review date, unless prior arrangements are made, page 2 APPLICANT Name_ Earl Worslev _ _ — Company Worsley Investment and Development Co. LLC� Address P.O. Box 490 City/State Wrightsville Beach Zip 28480 County New Hanover Phone 910-256-0044 Fax 910-256-0044 Email PROJECT Name_ Preservation irk ENGINEERICONSULTANT_ Phillip Tripp Company TrippEngineering Address 419 Chestnut Street . CitylState Wilmington, NC_ _Zip 28401 County New Hanover Phone 910-763-5100 Fax 910-763-5631 Email trip aeng(a7e�,mcom — _ ❑ STREAM ORIGINATION CERTIFICATION L�NSTORMWATER ®tLow�Density High Density -Detention Pond ❑ High Density -Other ❑ Wv4 Density -Curb & Gutter High Density -Infiltration ❑ Off Site ❑ COASTAL ❑ Excavation & Fill - ❑ Bridges & Culverts ❑ Structures Information MANAGEMENT '❑ Upland Development ❑ Marina Development ❑ Urban Waterfront ❑ LAND QUALITY ❑ Erosion and Sedimentation Control Plan with — acres to be disturbed. ❑ WETLANDS (401) ❑ No Wetlands on Site (letter from COE) ❑Wetlands Delineated/No JD ❑ Greater than 0.1 AC. Wetlands Impacted ❑Jurisdictional Determination has been done ❑ Less than 0.1 AC Wetlands Impacted ❑Greater than 0.5 AC Wetlands Impacted The legislation allows additional fees, not to excoed 50% of the original Express Review permit application fee, to be charged for subsequent reviews due to the insufficiency of the permit applications. For DENR use only SUBMITTAL DATES: Fee Split for multiple permits: SW $ CAMA $ LQS $ 401_ $ Total Fee Amount $ MAR 10,2005 04:17P 9107635631 page 3, March 10, 2005 Stormwater Narrative Preservation Park Wilmington, NC 77��s . ` Preservation Park is a 3.06 acre tract proposed for nine single family honks. Approximately 2.0 acres of th(� site will remain natural with same minor clean up of overgrown vegetation. The 1.06 acres is to be cleared and graded. TE 041,35 Sto1e11watcr will be treated by extended detention wetland tacilit The pond will be designed for the State's 1" and the Cit 's 1U y_�ar pre -past requirements. Approximately 0.95 acre will drain to the facility. Within the 0.95 acre, the nine single family homes will create 11.808 sf of impervious along with 4,401 sf of concrete driveways and sidewalk a5 well as 3,532 sf of asphalt street. A total of 19.741 sf creates a 14.7% builtluPor area -for the project. Overflow from the site will be routed to Bradley creek, Classification C-S W. •M4AR 10,20G5 04:17P 9107635631 i page 4 OWNER INFORMATION: WORSLEY INVESTMENT AND DEVELOPMENT, LLC P.O. BOX 490 WIL.MINGTON, NC �o MA.R 10, 2005 04 :16P 9107635631 m °m Job No. 1 r Tf �� `i `�-5 Date: 3 ` T z'Y- 7 ,0,� Sci b.�J 10 �-g U �t +R'1VP ENGINEERING, P.C. 4I9 Chestnut Street, Wilmington. NC 2840 ho e: (910) 763-5100 - FAX: (910) 763-5631 0 el Email: trippeng(Duec.rr.coin LE r TER OF TRANSMITTAL To: Attention Subject'. J� m 1' TV )1 P FAX TRANSMITTAL: NUMBER OF PAGES INCLUDES COVER I am sending you: (ATTACHED ( ) UNDER SEPARATE COVER ( ) Prints ( ) Tracings ( ) Copy of letter ( ) Specifications ( ) Other Copies _ Item No. Description_ M These are transmitted as checked below: ( ) For Approval ( ) For Your Use ( ) Sign & Return (-J'Review cc: Signed: page 1 f March 10, 2005 Storm water Narrative Preservation Park Wilmington, NC TE 04135 Preservation Park is a 3.06 acre tract proposed for nine single family homes. Approximately 2.0 acres of the site will remain natural with some minor clean up of overgrown vegetation. The 1.06 acres is to be cleared and graded. Stormwater will be treated by extended detention wetland facility. The pond will be designed for the State's F and the City's 10-year pre -post requirements. Approximately 0.95 acre will drain to the facility. Within the 095 acre, the nine single family homes will create 11,808 sf of impervious along with 4,401 sf of concrete driveways and sidewalk as well as 3,532 sf of asphalt street. A total of 19,741 sf creates a 14.7% built upon area for the project. Overflow from the site will be routed to Bradley creek, Classification C-S W.