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Home My WebLink AboutSW8020613_COMPLIANCE_20021120STORMWATER DIVISION CODING SHEET POST -CONSTRUCTION PERMITS PERMIT NO. DOC TYPE ❑CURRENT PERMIT ❑ APPROVED PLANS ❑ HISTORICAL FILE COMPLIANCE EVALUATION INSPECTION DOC DATE YYWMMDD k STORMAVATER CALCULATIONS FOR NORTH CAROLINA DIVISION OF WATER QUALITY FOR SOUNDVIEW PARK— PHASE II PENDER COUNTY NORTH CAROLINA RECEIVED ",{,,,,,,. NOV 2 0 2002 - = SEAL DWQ 1 74z �GU ?6 20ce >> q/o Z PR0J# ----- ENGINEERS WK DICKSON & CO., INC. 909 MARKET STREET WILMINGTON, N.C. 28401 (910) 762-4200 SEPTEMBER 4, 2002 (Revised 11/19/02) WK DICKSON Engineering Land Planning Surveying INFILTRATION BASIN CALCULATIONS Total Area - °,37843' SF----1 Pervious Area = E� 12,019SF > % IMP = 68.2% Impervious Area = 1 25,824 SF----1 >Determine the storage volume required to hold the first 1-112 inches of runoff. Schueler's Method: X = 0.05 + 0.009 (% IMP) = 0.664 Volume = (15712) x Total Area x X = 3142 CF >Determine the storage volume provided. Contour Elevation Area Volume (FMSL) (SF) (CF) 3 0 3365 0 ; `3453� 341 YS 32,EsyN'3541 691 3 3, "` '� , ,,3630 ,' 1049 3 4' k,437a19 1417 -L ! 1793 = 3 6 r 3899 2178 4 'N 3 7 ' 3 3990 2573 rh . 4082 .1 2976 F4128 3182 Storage volume provided @ elev. 3.85 > volume required. 909 Market Street Wilmington, NC 28401 (910) 762-4200 0 WK DICKSON Engineering 909 Market Street Land Planning Wilmington, NC 28401 Surveying (910) 762-4200 Determine time required for stored runoff to fully infiltrate. Darcy's Law: Q = kkonom(h/L) where: k = 6 inlhr (from soils report) A W bottom area of infiltration basin sf L = bottom elev. - SHWT elev. = 3.0' - 1.5' = 1.5' h = water surface elev. (varies) Contour Area Incremental Infiltration Release Elevation Storage Rate, Q Time (FMSL) (SF) (CF) (CFS) (HRS) 3 85 �� { _4128 ;,t 205 0.73 0.07$ 8 a �I 404 0.72 0.156 i ;40$2 �_ 3i7'`3�it3990-�� 394 0.69 0.160 3 6` ni3 3$99 1 385 0.65 0.164 3809 A11 376 0.62 0.168 371911 367 0.59 0.172 3630 X` 359 0.56 0.178 3541 �s 350 0.53 0.183 �3453 341 0.50 0.190 3 0 0 0.00 0.000 Total Drawdown Time = 1.21 Hours INFILTRATION BASIN ANALYSIS PROJECT !NUMBER: 020613-1 PROJECT NAME: Soundview Park Phase 2 DRAINAGE BASIN: Cape Fear RECEIVING STREAM: Topsail Sound Index No.: 18-87-10 SITE AREA 7.64 acres IMPERVIOUS AREA CALCULATION BUILDINGS PARKING/ASPHALT CONCRETE OTHER TOTAL % IMPERVIOUS, 1- ELEVATION OF SEASONAL HIGH WATER TABLE REPORTED INFILTRATION RATE SURFACE AREAS AND ELEVATIONS FILENAME: G:IDATAIWPDATAIWQSIINBASIN102061 DATE: 11-Dec-02 REVIEWER: L. Lewis CLASS: SA If ORW, is site within the 575' AEC? DRAINAGE AREA: 37843 SF _61INCHESIHOUR or 0.000139 FPS Elev. (ft) Area, sq ft Inc. Volume Acc. Volume BOTTOM 3 3365 3.2 3541 690.6 690.6 3.5 3809 1102.5 1793.1 3.7 3990 779.9 2573 TOP 3.85 4128 608.85 3181.85 VOLUME 1 DEPTH 1 DRAWDOWN CALCULATION DESIGN STORM, INCHES DESIGN VOLUME TOTAL VOLUME AVAILABLE DEPTH OF RUNOFF TIME TO DRAWDOWN 25 YEAR 24 HOUR STORM N/A Intensity, i = .33 inches 1 hour Qr=CiA= Qp through the bottom of the basin= 10 YEAR 10 MIN HIGH INTENSITY EVENT Intensity, i = 6.3 inches 1 hour Volume for 10 yr. 10 min. event = CUBIC FEET CUBIC FEET FEET HOURS MUST BE <120 0.21 CFS 0.47 CFS Must be > Qr 2449.52 CF < 2573 CF COMMENTS Volume and drawdown are within Design Requirements. INFILTRATION BASIN ANALYSIS PROJECT NUMBER: 020613-1 PROJECT NAME: Soundview Park Phase 2 DRAINAGE BASIN: Cape Fear RECEIVING STREAM: Topsail Sound Index No.: 18-87-10 SITE AREA 7.64 acres IMPERVIOUS AREA CALCULATION BUILDINGS PARKING/ASPHALT CONCRETE OTHER TOTAL % IMPERVIOUS, 1= ELEVATION OF SEASONAL HIGH WATER TABLE REPORTED INFILTRATION RATE SURFACE AREAS AND ELEVATIONS FILENAME: G:IDATAIWPDATAIWQSIINBASIN102061 DATE: 15-Nov-02 REVIEWER: L. Lewis CLASS: SA If ORW, is site within the 575' AEC? DRAINAGE AREA: «<..37843 SF FEET M S L INCHES/HOUR or 0.000139 FPS Elev. (ft) Area, sq ft Inc. Volume Acc. Volume BOTTOM 3 4077 3.2 4330 840.7 840.7 3.5 4715 1356.75 2197.45 TOP 3.7 4974 968,9 3166.35 VOLUME 1 DEPTH 1 DRAWDOWN CALCULATION DESIGN STORM, INCHES DESIGN VOLUME TOTAL VOLUME AVAILABLE DEPTH OF RUNOFF TIME TO DRAWDOWN 25 YEAR 24 HOUR STORM NIA Intensity, i = .33 inches 1 hour Qr=CiA= Qp through the bottom of the basin= 10 YEAR 10 MIN HIGH INTENSITY EVENT Intensity, i = 63 inches 1 hour Volume for 10 yr. 10 min. event = CUBIC FEET CUBIC FEET FEET HOURS MUST BE <120 0.21 CFS 0.57 CFS 2449.52 CF < COMMENTS Volume and drawdown are (not) within Design Requirements. Must be > Qr 3166.35 CIF