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Home My WebLink AboutSW4200901_Project Optic Calc Book 08.31.20_20200914PROJECT OPTIC ROCKINGHAM COUNTY, NC STORMWATER CALCULATIONS -awe r � rr + 'ice i � -895 'r i' �.��: l + Q r �-� � ❑ 5 •r- '�'`-'t ' 11J fb`-_`l'�' + � - 895 J'�' _ - � , ` •`M[rTpRpzppTpN � I V l � wIPE, iuILItNF'SS=�]' f CA�IRI lam' �'Ir W IN9T/1LYQkYG'LtA967 75 L em`row� -areiw ' PREP PMON 0.0E C\�875.51/ ,lldl-&TMaF W51NPOOL VPLUIE 'VOL- &M OF uuriPooF vowraE) . pIIIII r zP4aa'wl�o a9=aP� _ •%'�e%5.5�•�/ _ _ 'rflr IRIPINPLPAOONS1' SMW 5F FOFffiwY - _ BOTTOM E--ONIN M 1 90LFN'RCP' % VOL--r5.]Y. OF MN POOL VOLUMM I LAEI5M CaHaI Mom.Y 9 15F MRIM TI=P079.00' r` / .. _ .. - I�Pl1IYWd fEST� EIEV 891LQ 11 S1OE4LOPE3 9`,�'PRECJLi`3-. I'_ ] • - ASq. / \ WNLR"RI€M , � ` � / r TFx PJr;B1a.W ' � iIINEp ENG �RyE[,FrFwieo sfwn� V y Y __ _ _ tl ' BECTIDH jC. A. L' !r OPJfrlp SPILLWAY' �Llv•lB�OP !. Y�I_.%�� - 'V.. ter.` f+rr �I •� J --- - \_ �'`e ♦4 � ~`---- ` ��`V! ,,== PRO L �4T1.5'WIDE� IDlp1E65=�'t� I /\ c fr - f ' / ~_ - - +✓I,; �� - i.�t��-r t t t �+ .-j r Y .r-'-+t`,_ �.��t, v ,��i �� i AUGUST 31, 2020 PREPARED BY: Adam Carroll, PE 8642 W. Market St., Suite 136 Greensboro, NC 27409 336.478.3346 adam.carroll(aOmmons.com I IIII//// SEAL = 38573 Y-3140 v T. I/Vo I C TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Table of Contents - NOAA Precipitation Frequency Data - Inlet Weighted C-Value Table - Pipe Capacity Calculations - Pipe HGL Calculations - Outlet Protection Sizing - Culvert Calculations - Wet Pond Sizing "&*see 1 www.timmons.com TIMMONS GROUP YVV'V YI SIVH RLHILYEO THRVU LH VVRS. 5/22/2020 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Stokesdale, North Carolina, USA' Latitude: 36.26440, Longitude:-79.93250 Elevation: 904.97 fr* 'source: ESRI Maps k " source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. IZley NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1 Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 4.45 (4 .09-4.85) 11 5.30 (4.87-5.77) 11 6.22 (5.71-6.77) 11 6.84 (6.26-7.43) 7.54 (6.88-8.17) 7.98 (7.25-8.66) 8.38 (7.58-9.10) 8.71 (7.84-9.47) 9.06 (8.09-9.85) 9.28 (8.22-10.1) 3.56 4.24 4.98 5.47 6.01 6.35 6.66 6.91 7.16 7.31 10-min (3.26-3.87) (3.90-4.62) (4.57-5.42) (5.01-5.95) (5.48-6.51) (5.77-6.89) (6.02-7.23) (6.22-7.51) (6.40-7.79) (6.47-7.96) 15-min 2 72 3622 3.27 3587 3.86 4058 4.22 5101 4.63 5850 4.87 5682 5.08 6109 5.23 6132 5.37 6154 5.42-6.66 2.03 2.45 2.98 3.34 3.76 4.04 4.30 4.52 4.78 4.95 30-min (1 .87-2.21) (2.26-2.67) (2.74-3.25) (3.06-3.63) (3.43-4.07) (3.67-4.38) (3.89-4.66 ) ( 4.07-4.92) ( 4.27-5.21) ( 4.39-5.39) 1.27 1.54 1.91 2.17 2.50 2.74 2.96 3.17 3.43 3.61 60-min (1.16-1.38) (1.42-1.68) (1.76-2.08) (1.99-2.36) (2.28-2.71) (2.49-2.97) (2.68-3.21) (2.85-3.45) (3.06-3.73) (3.20-3.94) 0.747 0.907 1.14 1.31 1.52 1.69 1.85 2.01 2.22 2.37 2-hr (0.686-0.816) (0.832-0.991) (1.04-1.24) (1.19-1.42)1 (1.39-1.66) (1.53-1.84) 1 (1.66-2.01) 1 (1.79-2.19) 1 (1.96-2.41) 1 (2.07-2.58) 0.534 0.649 0.814 0.935 1.09 1.21 1.33 1.44 1.59 1.70 3-hr (0.491-0.582) (0.598-0.709) (0.748-0.886) (0.856-1.02) (0.993-1.18) 1 (1.10-1.31) 1 (1.20-1.44) 1 (1.29-1.56) 1 (1.40-1.73) 1 (1.49-1.85) 0.328 0.396 0.496 0.573 0.677 0.759 0.843 0.927 1.04 1.13 6-hr (0.302-0.358) (0.366-0.434) (0.456-0.542) (0.525-0.624) (0.615-0.735) (0.685-0.823) (0.754-0.912) (0.820-1.00) (0.909-1.13) (0.973-1.23) 0.194 0.235 0.296 0.344 0.412 0.467 0.525 0.586 0.672 0.741 12-hr (0.179-0.213) (0.216-0.258) (0.271-0.323) (0.314-0.375) (0.373-0.447) (0.419-0.506) (0.467-0.567) (0.514-0.632) (0.578-0.725) (0.627-0.800) 0.117 0.141 0.177 0.207 0.248 0.282 0.319 0.357 0.412 0.457 24-hr (0.108-0.126) (0.131-0.152) (0.164-0.191) (0.191-0.222) (0.228-0.267) (0.259-0.303) (0.290-0.342) (0.323-0.384) (0.369-0.443) (0.405-0.493) 0.068 0.082 0.102 0.118 0.141 0.159 0.177 0.197 0.225 0.247 2-day (0.063-0.073) (0.077-0.088) (0.095-0.110) (0.110-0.127) (0.130-0.151) (0.146-0.170) (0.163-0.190) (0.180-0.212) (0.203-0.242) (0.222-0.267) 0.048 0.058 0.072 0.083 0.099 0.112 0.125 0.139 0.158 0.174 3-day (0.045-0.051) (0.054-0.062) (0.067-0.077) (0.078-0.089) (0.092-0.106) (0.103-0.120) (0.115-0.134) (0.127-0.149) (0.144-0.171) (0.157-0.188) 0.038 0.046 0.057 0.066 0.078 0.088 0.099 0.110 0.125 0.138 4-day (0.036-0.041) (0.043-0.049) (0.053-0.061) (0.061-0.070) (0.073-0.084) (0.082-0.095) (0.091-0.106) (0.100-0.118) (0.114-0.135) (0.124-0.149) 0.025 0.030 0.037 0.042 0.050 0.056 0.062 0.069 0.078 0.085 7-day (0.023-0.027) (0.028-0.032) (0.034-0.039) (0.039-0.045) (0.046-0.053) (0.052-0.059) (0.057-0.066) (0.063-0.073) (0.071-0.083) (0.077-0.092) 0.020 0.023 0.029 0.033 0.038 0.042 0.047 0.052 0.058 0.063 10-day (0.019-0.021) (0.022-0.025) (0.027-0.030) (0.030-0.035) (0.035-0.040) (0.039-0.045) (0.043-0.050) (0.048-0.055) (0.053-0.062) (0.057-0.068) 0.013 0.016 0.019 0.021 0.024 0.027 0.030 0.032 0.036 0.039 20-day (0.013-0.014) (0.015-0.017) (0.018-0.020) (0.020-0.022) (0.023-0.026) (0.025-0.029) (0.028-0.032) (0.030-0.035) (0.033-0.039) (0.035-0.042) 30-day 0.010-0.012 0.01 -0 014 0.014-0 016 0.016-0 018 0.018-0 020 0.020-0.022 0.021--0 024 0.02 -0 025 0.024-0 028 0.026-0 030 0.009 0.011 0.012 0.014 0.015 0.017 0.018 0.019 0.021 0.022 45-day (0.009-0.010) (0.010-0.011) (0.012-0.013) (0.013-0.014) (0.015-0.016) (0.016-0.018) (0.017-0.019) (0.018-0.020) (0.019-0.022) (0.020-0.023) 0.008 0.010 0.011 0.012 0.013 0.014 0.015 0.016 0.017 0.018 60-day (0.008-0.009) (0.009-0.010) (0.011-0.012) (0.011-0.013) (0.013-0.014) (0.014-0.015) (0.014-0.016) (0.015-0.017) (0.016-0.018) (0.017-0.019) Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=36.2644&Ion=-79.9325&data=intensity&units=english&series=pds 1 /4 5/22/2020 Precipitation Frequency Data Server I ONSIOSE 1.000 41 e W 3415 DR 0 001 10.000 1.000 41 c a, 0.100 O ,9 9L V2 0.010 r PD5-based intensity -duration -frequency (IDF) curves Latitude: 36.2644', Lcngitude:-79.9325' ------------- - - - - - - - - - - - - - r - - - i s tL z t ra roM FO M M M roM yy p p rl fV CV f1�1 q rx O O O Ln O rn �n � ry rn ITrc Duration 0.0011 1 2 5 10 25 50 100 200 500 1000 Average recurrence interval (years) NOAA Atlas 14, Volume 2, Version 3 Created (GMT): Fri May 22 13:30-00 2020 Back to Top Maps & aerials Small scale terrain Average recurrence interva I {years} — 1 2 — 5 — 14 — 25 54 100 200 500 1000 Duration — 5-min — 2-day — I D-min — 3-day 15-min — 4-day — 34-min — 7-day — 50-min — 10-day — 2-hr — 2"ay — 3-hr — 3"ay — "r — 45-day — 12-hr — 50-day — 24-hr https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=36.2644&Ion=-79.9325&data=intensity&units=english&series=pds 2/4 5/22/2020 Precipitation Frequency Data Server Large scale terrain * Lynchburg Blacksburg Roanoke "i �tc•I O h Winston-Salem • I . Guii7am Greensboro 11 r-litrnell Nl� Raler + ille NOF.TH CAROLINA — 100km I 7tte Fa etteAle. Large scale map rit n5 Ile Large scale aerial https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=36.2644&Ion=-79.9325&data=intensity&units=english&series=pds 3/4 5/22/2020 Precipitation Frequency Data Server Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC.Questions@noaa.gov Disclaimer https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=36.2644&Ion=-79.9325&data=intensity&units=english&series=pds 4/4 f u :6 w cm i O O O O O O O O w Q 00 00 00 N 00 00 Q D 0 D O D *' O w -tea O Q w Z Ln O w U = U as LqO H o N u Q m Z w l0 l0 -i M -i Ln Ln O m -i l0 M Ln Ln l0 Ln Ln O J Z Z t 00 I� 00 l0 l0 M M l0 I- M M I- M M r� M M � O O O O O O O O O O O O O O O O O O O w 0 Q O LU O a w Z Q � M Ln N Clio l0 -tt O [V M M [V [V cc or- cc 0 0 cI -i N O O O M M cI cI cI cI O O cI O O i O M O O O O O O O O O O O O O O O O O u :6 co OJ Q 3 O OJ a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 rl moo moo I1 n 01 N 00 O M I, n 01 111 �t 000 -i I* MI Lq M D O O M Lq Lq Lq I* N N Lq 1 u O M O O O O O O O O O O O O O O O O O :6 co OJ Q io O H H W J Z f6 O Q M lA N C1 Q C1 U C1 W 0 rl rl M rl lA rl N rl C1 rl rl N M N lA N P% N m N r•I M OJ OA f6 C i ~ z U U 0 ~ z U Z) d U O N z _O a a 2 O U z H O N w � U z �w w O LU N Ir LL O (n U) x a W a --0000000000000000000 w a cccccccccccccccccc. Q U U U U U U U U U U U U U U U U U U U Z C C o C C o C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C o C C 0 C C 0 C C 0 C C 0 C C 0 C C 0 a Q - w W U x w o a .. . Ca U Ca e d m d d d c d e d e d r d c d c d c d c d c d c d c d c d- d Q U ¢- Lj U Q Lj . . a . . aLj o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d Q Q " C _ C C r. C . C . C . C . C r C ri C C C C C N C N C C C C `� d ri o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o d Q F F � PO. W � z _ w x H 0 a w o z a W O !N !N } a z a w z J J w m aot a a 00 o a U w U 'a w a U } Z x _ h O 7 M O O h M M 0 0 N E E 00000000000000 E M L6 M h O m M N N M N h h Cp CO h CO O CO N CL w In M m mN O O O O CO In In In O rn rn rn rn rn rn rn rn rn rn rn rn o N N N r M M Nr-: L r Q x w M O CO In 6 M N CO N O LqO O O c O LL N 0 0 - 0 0 0 0 w w w w w w w w w w w w w w o co co J J U U J J U UUUUUUUU J J J J J J J J U J J Q Q LL LL Q Q LL LL Q Q LL LL Q Q LL LL Q Q LL LL Q Q LL LL Q Q LL LL N O O � M M S CO CO S CO CO h M - MM - O O O O O O O W M M M M M M M N N N 2 O O O O O O O O O O O O O O O Z ° � Z CO M 7�� CO O h CO h CO M M M O M13� M N N QO CEO � M M M O O M M I M M OM N M N N N L 0 N O h h O O h h h h CO CO � � O I LL h� N N N N N N N N N M COO N N M O W Z Z � O a a a a a a a a a a a a a a F w h h M h M O N w � � N CO CO w d W O N O O r N U O N O O O4 O O W O N� � Q w � N N N N N CO CO CO CO CO CO 0 0� M � 0 0 Y 0 0 o O m m m m m m m rn° rn F O w F z F z ° w Z O Z N N N N INNER %, IN iiiiiiiN iiiiiiifii Ml Mi _ iiiiiiFa ■u■ 1?i�iil ■■ ■■�i'I ■� i■11■ .EE..i .EE.ELI .Eiiir NON in SEE r ter. =20 awaaa.Er4- aaaaaaaaEe . rE.i..i. arrraraaa WIwW w i w W.N!l! !!!!!!!!!!! w w. %r w a m tiA wr !!!!!!A!!!►�!� 4Yi acw�w��raw!!!!llwia■w■wwr+la �w loom■a'I■ice■■■■■Boo ■■■ MEMO ■■klz%v BYli r `.7!!!! w!!!! xxxmms=lmsZLI ik ais__i :::m:mm AcOm;", ww wlwrfa WE !!!!n Mid i!s!!-1 ROMEM . =L kR.... •. a ME ■...o. INN i�ii i� i�i� E i, :r ErrrE�wrrE vE�sEiru+�r� EElalltflEl EEElEOEEE EiEElEHR' E E! E! I E E f E C iE lE!!lEEEri E r!!lEY:= i Ei�/i■R rsylr,.lrliilrriiEEElEiiln =i ! R!!N!\l�l► fayr!!!!! 1!!N!!l�l.�Ltil� V MEN ■■w ■■w now mom WR �*rvert to )� 4't +� 1 9-A-4 CHART 1 HEADWATER DEPTH FOR CONCRETE PIPE CULVERTS WITH INLET CONTROL O 180 10,000 (1) (2) (3) 166 8,000 EXAMPLE D = 42 Inches (3.5 feet) 6 156 6,000 0 =120 cfs 6• 144 5,000 6. 5. 5. 4 000 pW eW et 132 3,000 (1) 2.5 9.8 5. 4. 4. 120 2,000 (2) 2.1 7.4 4' 108 (3) 2.2 7.7 3. 3. 96 *D in feet .3 - 1,000 80084 600 / 2- 2. Cl) 500 z. U 72 400 / O Z 300�e/ = 1.5 1.5 0 80 U) 200 / / W 1.5 / H ix:54 Z / UJ UJ W J 48 '� - 100 Q BO Z CW7 - 60 1 IL 42 tr 50 0 U 40 UJ 1.0 W36 p 3U 9 9 HW SCALE ENT CE Q 9 Q 33 U E ~ 20 Q 8 6 l7 30 (1) :;Iuw++ edge wtth .6 27 headwall 10 (2) Groove end with = 24 headwall .7 .7 .7 6 (3) Groove and projecting 21 5 4 To use scale (21 or (3) project 6 horizontally to scale (1), then 6 .6 3 use straight Incline line through 18 D and 0 scales, or reverse as illustrated. 2 15 .5 1.0 .5 .5 I` 12 n + ccLJbar = I�r� 66�w. - AV, t p IDJ 3. 0s� 63 CFf Culverts 9-A-4 ��ve t OK TrL VVL% Ole Culverts CHART 1 HEADWATER DEPTH FOR CONCRETE PIPE CULVERTS WITH INLET CONTROL O 180 10.000 (1) (2) (3) 168 8,000 EXAMPLE 156 - 6,000 D = 42 Inches (3.5 teat) 0 =120 cis 6. 6. 144 4,00�0 w H 6. 5 5. feet 132 - 3,000 (1) 2.5 8.9 5• 4. 4. 120 - - 2,000 (2) 2.1 7.4 q, 10B (3) 2.2 7.7 3' 3. 96 "D in feet 3 1,000 84 800 2- 2. W 600 500 / / / U 72 400 z. ? 300 p�e/ = 1.5 1.5 Z/ 0 - 60 ILL200 / / W 1.5 54 U Z / LU v 100 a_ U 48 80 lL 42 0 cc 60 1.0 O � = U 50 0_ a. 1.0 — �— LU 36 0 30 .9 9 LLJ HW SCALE ENTRANCE - TYPE Cr w 9 Q 0 30 20 (1) square edge with a .8 8 .9 27 headway L7 10 (2) Groove and with •� `^ 7 -7 .7 6 (3) Groove and projecting 21 5 4 r r: r.se ,c ae (2) or (3) project no, izontiliy to scale (1), then - 6 •6 18 3 use strei9n' u:Girin Ir•e ur (-Ugh D and O s�:�in,:- r:r rc:r: se as .6 Illustrated. 2 15 •5 .5 12 clw. - �inv�� fl� � 0 9-A-4 6Werb' RSSa CA, or. C- (-,� cF� Culverts CHART 1 HEADWATER DEPTH FOR CONCRETE PIPE CULVERTS WITH INLET CONTROL O 180 10.000 EXAMPLE(1) (2) (3) 168 166 8,000 6,000 D = 42 Inches (3.5 feet) Q = 120 cfs 6. 6. 144 5,000 W 6. 5. 5. 4,000 f et 132 3,000 (1) 2.5 e.e 5. 4. 4. 120 2,000 (2) 2.1 7.4 4, 108 (3) 2.2 7.7 3' 3. r 96 •D in feet 3 L 1,000 84 800 r 2 w 600 500 / O 2. - U 72 400 F / / ? 300 / = 1.5 1.5 Z E� / v 60 LL 200 / / W 1.5 Z / - 48 100 Q ° � L / w 80 Z 1.0 1.0 42 Q 5500 1.0 I = C.)W - 40 w tj 36 p 30 HW SCALE ENTRANCE p CC .9 .9 .9 33 TYPE 20 0 30 (i) Sc{uiiru odge with Q � 8 .8 .8 27 �icadwai° 10 (2) Groove end with headwall = 24 8 6 (3) Groove and projecting 7 .7 .7 O , (pg 21 5 4 uae acale oor (3) rcject horflordadty to state 0). then .6 •6 3 uae aVafghl indlne Ilna through ❑ and Q asates, or reverse as .6 tltusirntad. 2 15 •5 1.0 .5 .5 12 Nv { • p �g0.5 9-A-4 CAI vet Sbq! Culverts CHART 1 HEADWATER DEPTH FOR CONCRETE PIPE CULVERTS WITH INLET CONTROL O (1) (2) (3) 10 10,000 8,000 EXAMPLE D = 42 Inches (3.5 feet) 6 6,000 0 =120 cfe 6. 4 5,000 HW " HW 6. 5. 5. 4,000 D feet 12 3,000 (1) 2.5 8.8 5. 4. 4. i0 2,000 (2) 2.1 7.4 q, )B (3) 2.2 7.7 3' 3. •D In feet 36 1,000 .3 800 as r 600 / 2• 500 / / 2. 72 400 �. / F� 300 atsp/ 1.5 1.5 60 200 / (r 1.5 U ~W~ 54 Z / W 100 Q 48 80 / W Z 42 (r 60 = 1.0 1.0 40 a 1.0 U LU 36 � 30 p .9 .9 p HW SCALE ENTRANCE a: ,9 33 -� TYPE H 20 Q .B 30 (1) Square edge with 0 .8 .8 27 headwall 10 (2) Groove and with = 8 headwall 7 .7 .7 24 6 (3) Groove and projecting 21 5 ,�p3 q To use scale (2) or (3j project 6 hodtpntelty to scale .6 3 o use "Qu18 D or reverse as .6 uslntW. .5 1.0 .5 .5 L- 12 F�cz�ow-c� �A&.� L Av. t Hw pl � J 2.2t' 9-A-4 �I Wjt 64 l �l w cern.r F i3 ato e r5 Culverts CHART 1 HEADWATER DEPTH FOR CONCRETE PIPE CULVERTS WITH INLET CONTROL O 180 - 10,000 (1) (2) (3) 168 EXAMPLE 8,000 156 D = 42 Inches (3.5 feet) 6,000 O = 120 cfs 6 6. 144 5,000 HW • HW 6. 5 5. 4,000 D feet 132 3,000 (1) 2.5 8.8 5• 4. 4. 120 2,000 (2) 2.1 7.4 4' 108 (3) 2.2 7.7 3. 3. 96 `D in feet .3 1,000 fia - 800 r. 2. COO 600 / 500 U 72 400 Z 300 sale/ 2 1.5 1.5 Z 0 60 LL 200 / / W 1.5 54 Z / W LU 48 1 00 Q p 1> U / C 0 LLO 1-19 42 Cr 50 1.0 1.0 1.0 Q = 40 1.0 0.1K W 36 30 .9 .9 33 p t HW SCALE FNTRANC TYP fi _9 tu- Q 0 30 20 (1)eadwallM�wiei Q .8 B B 27 10 Groove end with 6 headwall 7 7 .7 24 6 (3)arcova and projacling 21 5 4 To use scale (2) or (3) prMeat 6 horizontha tally to scale (1), n 3 alas sValght indino lino through .6 6 18 0 and p scales or reverre as iIIVB1f89Bd. 2 15 .5 1.0 .5 .5 12 F-15r� ne.. a.� 6�`W - AQ J WET POND SIZING - Pond (PER NCDEQ SEC. B) PHASE 1 Project: Project Optic Project N: 45919 Designed By: ism Date: 8/11/2020 Revised By: ism Date: 8/11/2020 Checked By: JAC Date: 8/11/2020 Drainage Area (AC): 25.72 Impervious Area (AC): 10.75 Pervious Area (AC): 14.97 Impervious Fraction: 0.417962675 Design Storm Depth, R, (m): 1 Pervious CN: 79 Impervious CN: 98 Rainfall Depth, P (in): 1 Calculating Design Volume (DV) Simple Method NRCS Curve Number Method R„ - 0.05+0.9-1" 5-1000/CN -10 Where, Where, Maximum retention after rainfall R„ - Runoff coeffient S- begins lin) q-Impervious Fraction CN- Curve number R„- 0.426 For lm pervious, 5- 0.200 For Pervious, 5- 2.658 DV - 3630*Ro*Rv`A Q. - (P - 0.25)'/ (P+0.85) Where, DV- Design Volume(CF) Where, Ro - Design Storm Depth (in) Q* - Runoff Depth (in) A- Drainage Area (AC) P- Rainfall Depth (in) DV- 39788 CF For lm pervious, Q*- 0.791 in For Pervious, Q. - 0.070 in R - (Q` x A)/12 Where, R- Runoff Volume(CF) A- Area of Impervious or Pervious (SF) For lm pervious, Ri- 30863.12 OF For Pervi R,- 3812.482 OF DV - Ri+R,- M676 OF Final Design Volume (DV) DV- 34,676 OF V., - 0.87*HRT/T,*DV Where, V my - Main pool volume not including forebay (CF) HRT- Requiredhydraulicresidencetime(14days) Ts - Average time between storm events (5 days) V., - 84,469.77 OF Mimi... Forebay Volume -15-A of DV - Maximum Forebay Volume - 20°b OF DV - Trial Forebay Depth (ft): 5.5 Min Required Forebay Area (SF): 23M Max Required Forebay Area (SF): 3072 Trial Main Pool Depth (ft): 5.5 Min Required Main Pool Area (SF): 15358 MIN BOTTOM AREA REQUIRED (SF): 17662 Required Main Pool Volume (CF) M470 Required Main Pool Area (SF) 15358 Main Pool Ave Depth (MP Volume/MP Area*)(ft) 5.5 *Main Pool depth equation chosen for scenario where shelf is not submerged Required Sediment Storage (6" x Min. Bottom Area Required)(CF) 8831 Actual Main Pool Volume (CF) 164676 Actual Main Pool Area (SF) 29941 Main Pool Ave Depth (MP Volume/MP Area*)(ft) 5.5 12670 OF 16890 CF fi r onra FIVE f �c Y � TEMPpMRT Pool ____ +I+! vea