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HomeMy WebLinkAboutWEBERG PUD - FINAL - 76-88G - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTMf:WINC Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 303/226-4955 June 5, 1989 Ms. Susan Hayes Storm Drainage Department City of Fort Collins P.O. Box 580 Fort Collins, Colorado 80522 RE: FINAL DRAINAGE REPORT FOR THE WEBER P.U.D. Dear Susan: The Weberg Furniture site is located about 1/2 mile south of Har- mony Road on the west side of Highway 287 (College Avenue in Fort Collins) in Larimer County Colorado. Annexation is currently underway to bring this site within City limits. More specifi- cally this location is in the east half of Section 2, Township 6 North, Range 69 West of the 6th Principal Meridian. This site currently is occupied by a residence with a large open grass field between it and College Avenue. The general slope of the property is at about 1% to 3% in a southeasterly direction. Existing drainage from this site flows in two directions. Basin H1 (on plan in pocket) drains to a drainageway that exists just south of this basin. Basin H1 is offsite and to the west of this site with an exception of proposed Basin A. Proposed Basin A will drain, however, in the direction of Highway 287. Drainage from Basin H2 drains directly into Highway 287. Calculations for the existing flows from Basin H2 is shown in the Appendix. Offsite flows from the north currently are captured into a drainage swale near the north property line. This drainage swale meanders on and off this property but exists primarily north of property line. The development of Lot 2 will require redefining this swale north of this site or make provisions for the offsite flows to safely pass through this site. The flows that enter highway 287 will drain in the existing curb and gutter as they travel south of the site. At a point about 400 ft. south of this site, an inlet will intercept some of the flows. This inlet collects the flows into a pipe which transports them to the east side of Highway 287, where the pipe daylights. The flows then sheet flow to a roadside ditch within the Fossil Creek Meadows Subdivision. Roadside ditches, along Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado (719) 598-4107 with culverts under existing roads within the subdivision, direct the flows to Fossil Creek. Flows that were not intercepted by the first inlet in Highway 287 will continue down the hill to another inlet. This inlet collects the flows to a pipe system which finally drains directly into Fossil Creek. This property is a part of the Fossil Creek Major Drainage Basin which is explained in the Fossil Creek Drainage Basin Master Drainageway Planning Study, by Simons, Li and Associates, Inc. August, 1982. Based on the above report, The City of Fort Col- lins does not require any storm water detention from this site in a totally developed condition. If drainage flows are directed to the ponds southwest of this site, however, the City Stormwater Utility Department requires an agreement with the downstream property owners to accept the additional runoff generated without detention. Such an agreement would involve all property owners between this site and Fossil Creek. This requirement is noted for the future development of the property to the west. No runoff is anticipated to flow to this area according to the final design, therefore no agreement is required for the Weberg site. Drainage water from this site flowing onto Highway 287 is required to limited to the historic runoff rate as stated in a letter to the City of Fort Collins,from the Colorado State High- way Department dated October 7, 1988. The approach that this report pursues is to release flows from this site at existing(historic)rates with these flows outfalling into Highway 287. This would require some storm water detention to keep the developed flows from exceeding existing flow rates. The final design proceeded based on this design requirement. The first design step is to calculate existing flows in Highway 287 to ensure that these flows do not already exceed the City of Fort Collins criteria during a 10 year storm. The allowable flow rate in Highway 287 at the south of this site based on Manning's formula is 18.9 cfs. Applying a city safety factor of 0.73 brings this flow rate to 13.8 cfs. This available flow rate is greater than existing flows of 13.1 cfs (see calculations in appendix) and therefore is within City requirements. Local streets are checked for the required curb flow capacity for the initial and major storms. In both cases the designed street meet the City's capacity requirements. The flows from these streets will enter the proposed detention areas through the park- ing access locations, inlets, or sidewalk culverts. The next design step is to create detention ponds for the developed basins in order to reduce developed flows to existing rates. In order to approximate existing flows, the 10 and 100 year developed storms were calculated for release rates and detention requirements. The calculations for Basins A, B, C, D, and E show that ponds are necessary, in these basins, to reduce flows to existing rates of Basin H2. The results of the calculations are shown in the fol- lowing table: 7j U (cfs) 100 YEAR EXISTING AND DESIGN STORM MAX. FLOW RATE (Ac.-Ft.) PROPOSED 100 YR DETENTION POND VOLUME (cfs) 10 YR EXISTING AND DESIGN STORM MAX. FLOW RATE (Ac.-Ft.) PROPOSED 10 YR DETENTION POND VOLUME Basin "A" 1.2 0.14 0.6 0.08 Basin "B" 0.6 0.07 0.3 0.04 Basin "C" 0.9 0.11 (roof top 0.4 0.06 storage) Basin "D" 0.8 0.10 (roof top 0.4 0.06 storage) Basin "E" 2.1 0.26 1.1 0.14 Basin "F" 1.7 ---- ___ Basin H2 7.5 ---- NOTE: The release rate calculations (existing 100 year flows) can be seen in appendix. All of the basins will either have ground surface or roof top detention facilities. The stage release (10 and 100 year storms) structure is designed and shown in the Appendix. The structures are of either an orifice type or weir type design. Local streets were checked for curb flow capacity and found to be within City criteria. The flows from these streets will enter developed basins through parking lot access locations, inlets, or sidewalk culverts. The sidewalk culvert for Basin "b" is shown in the Appendix. Storm water from this proposed development drains into a water quality facility prior to draining from this site. Table 1, in Appendix, from the paper, National Perspectives on Urban Runoff Technologies, by Larry A. Roesner, Ph.D., P.E. of CDM, shows dif- ferent types of facilities that can be used along with the average amount of pollutants that they remove. The facility chosen for this development is the infiltration type. This type of facility, as shown on Table 1, removes on the average 90% of the following pollutants: A) Suspended Solids B) Phosphorous (P) C) Dissolved P D) Nitrogen (N) E) Lead F) Zinc The infiltration facility design for this development is a water quality control berm. This berm is at the pond outlet pipes. The berm consists of redwood post and synthetic filter fabric connected to wire fencing material with gravel bermed up on both sides (see plan in pocket for detail). The gravel will be visually monitored once a year and replaced on an as needed basis. CONCLUSIONS AND RECOMMENDATIONS The grading and drainage facilities shown on the drainage plan should be complied with and will provide for the safe transport of storm drainage water through the site. The calculations which support this design approach appear the the Appendix of this report. Sincerely, Brian Cole, P.E. Project Engineer REFERENCES 1) Fossil Creek Drainage Basin Master Drainageway Planning Study, by Simons, Li and Associates, Inc. August, 1982. 2) Storm Drainage Design Criteria and Construction Standards, by the City of Fort Collins, May, 1984. 3) Letter to Ms. Linda Ripley of the City of Fort Collins Plan- ning Department from the State of Colorado Division of Highway (DOH File 45100), October 7, 1988. 4) National Perspectives on Urban Runoff Technologies, by Larry A. Roesner, Ph.D., P.E. of CDM, this paper is from; Urban Runoff Water Quality Seminar by the American Public Works Association, American Society of Civil Engineers, American Water Resources As- sociation and Urban Drainage and Flood Control District. cc: 322-002 I ivi NA B Do i T we for omwUl"M PJUNP5 10 • • APPENDIX 7- I 1-.1ANI F.',j VICINITY MAP Pi FOMI. A J.. IT 1. t M•t• ' 1w., ''_ ('- r ,� r "'�... Li.. �., Il �it``.A ...1, i�.D,I I •ram+"" i% i ,t' I' ; ��,l�l� .: }IL. II `9II •• II/ t I i� 1 .:'�, ` .l. •L.�,\ti` .,�. L 14 ill 3 Yj Lf C :-4 � Lj L . . . ........ lull -,If j .. 7-j L A".% tit, L • Y ;.gap IN I v 7 . .... JAI. 2 3 Rt ETOOTH r�H 0 ' Ad. ell L k. 4 e�4 �;t:�4AS- 'w" - g, v ov HARMONY ROAD \�'. r' SITE LOCATION lt�, r, 16 2 rwil � ' I 1 '� ''� .� . I t .. � t i .% t = 1 » `'yPi� •fir• 6 . P ;, s, rk � 6T 0 0 T MEIN HE FORM 5 RINC Engineering Consultants CLIENT I % �-- q-) L (L (L PROJECT w G-`�- G n •V -d . CALCULATIONS FOR 108 NO. MADE BY - DATE CHECKED BY DATE SHEET OF T:§INC Engineering Consultants #A 0 CLIENT - PROJECT MADE BY DATE CALCULATIONS FOR CHECKED BY DATE HISTORIC FLOWS TO HIGHWAY 287 ...I BASIN H 1-4 4-4 - } fit PL S Pt4. Z (b Z:Z Sec G 1 00 a I +� +- r r� I +ft _ I Q io-4 I _ - F T1— r { FI 1 I r - I Z3,Zt P'LL L) i - /Y\. E-'', 7E, .... 1 I .. Her Paik� . ARMONY ROAD -- -� ba k J r , BASIN "H" I ^ .. . ,.. .) •`. _._ _�� II � � t � 1. ! � .. _ ..I �j A3, -r LU-Wb I N A R ARTERIAL STREET CLIENT , !Nv-- PROJECT Engineering Consultants \MADE BY NO. CALCULATIONS FOR DATE CHECKED BY DATE SHEET OF N 4. m tT It ik Ct N �O - o o .ry N!•� I.t '. �..•. O { 1 `N }:N tll-III-;._o! t.;,•II, .daQ � , t• 1 f I 1 t 1 ..,.� .... y I i tJ.!.� } • CLIENT i JOB N0. !NC PROJECT CALCULATIONS FOR Engineering Consultants MADEBY DATE CHECKED BY DATE SHEET OF i! ��-t� 1.-f <_7 ��"�- i ` I .j •_ -�-J- ,\ , . T .i..;.. , _'- f -- I. ,..;.., r : I . ....... ....:.. 1 .-... ,...:. 1 ,� 1. �? L.'r.j._�.Z 0 _r ,.'7 i' ••" L i��l 1a. � �yi` � I ... 1 , ` I i � A�EE A . � l l i 0`4 ' -t-• ��-.�,`:5. ;._`_•,.. -� icji-�� ... � �' ;-t.- ..!- j_. l °1 b. \ -t t � `'t: L I L�•� I ;Q.aLa c_T , .., 1' I ! I t I .� I 1 F, •F•t•-...i..: ..1 ..}.., .�..i L �;I C� J L r + � Q i � �,7 2Z. ,•` , ; a 3t -, , , trZt ; i.: i . 4. A. • I I S rz Quo i:OZafZ a o305, C1: _ I Q400 313,7 C fil i..._. . `.. NI�TO(�l� C.. .;.. ..;.-_1 i � t I -, I I• . .,. I . %1 , {=7 U zo Ntx Oo W UU >z b N x a � Q CD,0�0 O cn Cl 0 C) 00 C O N N O C? O .-. oo O f-+ M O ~ VI 0 o a. N rz o \0 GO O O A N o v � 8� o H . M ~ V 0 0 n c U C � U A W W U u ¢ w C y L' _ 00 Ct1 0 cz iZ q�5 Caw, �3y FR-ot-�; CDM 0 MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 100 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) = RATIONAL EQUATION: Q = CIA C= TIME OF CONCENTRATION = A(area) = 1.08 TIME CA I INFLOW OUTFLOW STORAGE (sin) (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) _____________________________________________________________________ 5 1.08 9 2916 360 2556 0.058677 10 1.08 7.3 4730.4 720 4010.4 0.092066 15 1.08 6 5832 1080 4752 0.109090 20 1.08 5.2 6739.2 1440 5299.2 0.121652 25 1.08 4.6 7452 1800 5652 0.129752 30 1.08 4.15 8067.6 2160 5907.6 0.135619 35 1.08 3.8 8618.4 2520 6098.4 0'14 40 1'08 3.5 9072 2880 6192 0.142148 45 1.08 3.25 9477 3240 6237 0.143181~°-)N< 50 1.08 3 9720 3600 6120 0.140495 55 1.08 2.8 9979.2 3960 6019.2 0.138181 60 1.08 2.6 10108.8 4320 5788.8 0.132892 70 1.08 2.3 10432.8 5040 5392.8 0.123801 80 1.08 2.05 10627.2 5760 4867.2 0.111735 90 1.08 1.85 10789.2 6480 4309.2 0.098925 100 1.08 1.7 11016 7200 3816 0.087603 110 1.08 1.55 11048'4 7920 3128.4 0.071819 120 1'08 1'45 11275.2 8640 2635.2 0.060495 o) bD � v / _ n 0 BASIN °��" ������uu� u� MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 100 YEAR STORM �--> t-v�cope-c� MAXIMUM ALLOWABLE RELEASE (CFS) = 0.6 RATIONAL EQUATION: Q = CIA C = 1 A(area) = 0.53 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) _____________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 0.53 9 1431 180 1251 0.028719 10 0.53 7.3 2321.4 360 1961.4 0.045027 15 0.53 6 2862 540 2322 0.053305 20 0.53 5.2 3307.2 720 2587.2 0.059393 25 0.53 4.6 3657 900 2757 0.063292 30 0.53 4.15 3959.1 1080 2879.1 0.066095 35 0.53 3.8 4229.4 1260 2969.4 0.068168 40 0.53 3.5 4452 1440 3012 0.069146 45 0.53 3.25 4650.75 1620 3030.75 0.069576~°-41 50 0.53 3 4770 1800 2970 0.068181 55 0.53 2.8 4897.2 1980 2917.2 0.066969 60 0.53 2.6 4960.8 2160 2800.8 0.064297 70 0.53 2.3 5119.8 2520 2599.8 0.059683 80 0.53 2.05 5215.2 2880 2335.2 0.053608 90 0.53 1.85 5294.7 3240 2054.7 0.047169 100 0.53 1.7 5406 3600 1806 0.041460 110 0'53 1.55 5421.9 3960 1461.9 0.033560 120 0.53 1.45 5533.2 4320 1213.2 0.027851 AL �T--------------- \ -----�' zgom com �. , ` I vv* Z o .� L L 'J. ^ ' | | � ` | . | pp~ ����4�0�� =��" u����mu� �� MASS DIAGRAM METHOD ror DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 100 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) = 0.9 RATIONAL EQUATION: Q = CIA C = 1 A(area) = 0.81 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE _____________________________________________________________________ (min) (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 0.81 9 2187 270 1917 0,044008 10 0.81 7.3 3547.8 540 3007.8 0,069049 15 0.81 6 4374 810 3564 0.081818 20 0.81 5.2 5054.4 1080 3974.4 0.091239 25 0.81 4.6 5589 1350 4239 0,097314 30 0.81 4.15 6050.7 1620 4430.7 0.101714 35 0.81 3.8 6463.8 1890 4573.8 0.105 40 0.81 3.5 6804 2160 4644 0.106611 45 0.81 3.25 7107.75 2430 4677.75 0.107386--4� 50 0.81 3 7290 2700 4590 0.105371 ' 55 0.81 2.8 7484.4 2970 4514.4 0.103636 60 0.81 2.6 7581.6 3240 4341.6 0'099669 70 0.81 2.3 7824.6 3780 4044.6 0.092851 80 0.81 2,05 7970.4 4320 3650.4 0.083801 90 0.81 1.85 8091.9 4860 3231.9 0.074194 100 0.81 1.7 8262 5400 2862 0.065702 110 0'81 1.55 8286.3 5940 2346.3 0.053863 120 0'81 1'45 8456.4 6480 1976.4 0.045371 -�p . . cr-� ' o .��~ / 0 ��������� n��n ��uw���ux"m �� MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 100 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) = 0.8 RATIONAL EQUATION: Q = CIA C = 1 A(area) = 0.75 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) _____________________________________________________________________ 5 0,75 9 2025 240 1785 0.040977 10 0.75 7.3 3285 480 2805 0.064393 15 0'75 6 4050 720 3330 0.076446 20 0'75 5.2 4680 960 3720 0'085399 25 0.75 4.6 5175 1200 3975 0,091253 30 0.75 4.15 5602.5 1440 4162.5 0.095557 35 0.75 3.8 5985 1680 4305 0-098829 40 0'75 3.5 6300 1920 4380 0.100550 45 0.75 3.25 6581.25 2160 4421,25 0.101497-----)�- 50 0.75 3 6750 2400 4350 0.099862 55 0.75 2.8 6930 2640 4290 0.098484 60 0.75 2.6 7020 2880 4140 0.095041 70 0.75 2.3 7245 3360 3885 0.089187 80 0.75 2.05 7380 3840 3540 0.081267 90 0.75 1.85 7492.5 4320 3172.5 0.072830 100 0.75 1.7 7650 4800 2850 0.065426 110 0.75 1.55 7672.5 5280 2392.5 0.054924 120 0'75 1.45 7830 5760 2070 0.047520 -1 A -?7 - �£P7* &` o�-- --- ~-- --------- --- --- - » `=O, r"^� T'� A i� ��������� °��" . ��u����ou� �~ ���- /(��.z�1:_j�2b MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 100 YEAR STORM MAXIMUM ALLOWABLE RELEASE <CFS> = 2,1 RATIONAL EQUATION: Q = CIA C = 1 A(area) TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) _____________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 1.94 9 5238 630 4608 0.105785 10 1.94 7.3 8497.2 1260 7237.2 0.166143 15 1.94 6 10476 1890 8586 0.197107 20 1.94 5.2 12105.6 2520 9585.6 0.220055 25 1.94 4.6 13386 3150 10236 0.234986 30 1.94 4.15 14491.8 3780 10711.8 0.245909 35 1.94 3.8 15481.2 4410 11071.2 0.254159 40 1.94 3.5 16296 5040 11256 0.258402 45 1.94 3,25 17023.5 5670 11353.5 0'260640-Ae 50 1.94 3 17460 6300 11160 0.256198 55 1.94 2.8 17925.6 6930 10995.6 0.252424 60 1.94 2.6 18158.4 7560 10598.4 0.243305 70 1.94 2.3 18740.4 8820 9920.4 0.227741 80 1.94 2.05 19089,6 10080 9009.6 0.206831 90 1.94 1.85 19380.6 11340 8040.6 0.184586 100 1.94 1.7 19788 12600 7188 0.165013 110 1.94 1.55 19846.2 13860 5986.2 0.137424 120 1'94 1.45 20253.6 15120 5133.6 0'117851 ~0 :_ \. `�_/�^.�.� `- � BASIN "A" MASS DIAGRAM METHOD f nr DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 10 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) = 0.6 RATIONAL EQUATION: Q = CIA C = 0.85 A (area) = 1 . oe TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 o. g 18 5.65 1556.01 100 1376.01 0. c_1315e8 10 0. 918 4.4 2423.52 360 2063.52 0.047171 15 0.918 3.7 3056.94 540 2516.94 0 . 05778t i 20 0.918 3.25 358U. 2 720 2960.2 0.065661 25 0.918 2.85 3924.45 900 3024.45 0.069431 3o o . 918 2.6 4296.24 1080 3216.24 0. 073834 35 0.918 2.35 4530.33 1260 3270.33 0.075076 40 0.919 2.2 4847. 04 1440 3407. 04 0. 078214a-')E 45 c_> . 918 2 4957.2 1620 3337.2 2 0.076611 50 0.918 1.% 5094.9 1800 3294.9 0.075640 55 0.918 1.75 5301.45 198o 3321.45 0.07625 60 0.918 1.63 5386.824 2160 3226.824 0.074077 70 o. 918 1.44 5552. 064 2520 3032.064 0.069606 80 0.918 1.3 5728. 32 2880 2e48.32 0. 065388 90 i i . 918 1.2 5948.64 3240 27o8. 64 0.062181 100 0.919 1 . 1 6058. 8 3600 2458. 8 0.056446 110 0.918 1 6058.8 3960 2o98.8 0.048181 12� i o . 91. 8 0.9 5948. 64 4.320 1628. 64 i y . 027388 ���&��N�� "��" ��m�u°�mw�m �� MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 10 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) RATIONAL EQUATION: Q = CIA C = 0.85 A(area) = 0.53 TIME OF CONCENTRATION = ? TIME CA I INFLOW OUTFLOW STORAGE (min) _____________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 0.4505 5.65 763.5975 Q 673.5975 0.015463 10 0.4505 4.4 1189.32 180 1009.32 0.023170 15 0.4505 3.7 1500.165 270 1230.165 0.028240 20 0.4505 3.25 1756.95 360 1396.95 0.032069 25 0.4505 2.85 1925.887 450 1475.887 0.033881 30 0.4505 2.6 2108.34 540 1568.34 0.036004 35 0.4505 2.35 2223.217 630 1593.217 0.036575 40 0.4505 2.2 2378.64 720 1658.64 0.038077----)< 45 0.4505 2 2432.7 810 1622.7 0.037252 50 0.4505 1.85 2500.275 900 1600.275 0.036737 55 0.4505 1.75 2601.637 990 1611.637 0.036998 60 0.4505 1.63 2643.534 1080 1563.534 0.035893 70 0.4505 1.44 2724.624 1260 1464.624 0.033623 80 0.4505 1.3 2811.12 1440 1371.12 0.031476 90 0.4505 1.2 2919.24 1620 1299.24 0.029826 100 0.4505 1.1 2973.3 1800 1173.3 0.026935 110 0.4505 1 2973.3 1980 993,3 0.022803 120 0.4505 0.9 2919.24 2160 759.24 0.017429 ����*���� =��� ���m��mm� �� L�-tDpLc�, MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 10 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) = 0.4 RATIONAL EQUATION: Q = CIA C = 0.85 A(area) = 0.81 TIME OF CONCENTRATION = ? TIME CA I INFLOW OUTFLOW STORAGE (min) (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) _____________________________________________________________________ 5 0.6885 5.65 1167.007 120 1047.007 0.024035 10 0.6885 4.4 1817.64 240 1577.64 0.036217 15 0.6885 3.7 2292.705 360 1932.705 0.044368 20 0.6885 3.25 2685.15 480 2205.15 0.050623 25 0.6885 2.85 2943.337 600 2343.337 0.053795 30 0.6885 2.6 3222.18 720 2502.18 0.057442 35 0.6885 2.35 3397.747 840 2557.747 0.058717 40 0.6885 2.2 3635.28 960 2675.28 0.061415--f(L 45 0.6885 2 3717.9 1080 2637.9 0.060557 50 0.6885 1.85 3821.175 1200 2621.175 0.060173 55 0.6885 1.75 3976.087 1320 2656.087 0.060975 60 0.6885 1.63 4040.118 1440 2600.118 0.059690 70 0.6885 1.44 4164.048 1680 2484.048 0.057025 80 0.6885 1.3 4296.24 1920 2376.24 0.054550 90 0.6885 1.2 4461.48 2160 2301.48 0.052834 100 0.6885 1.1 4544.1 2400 2144.1 0.049221 110 0.6885 1 4544.1 2640 1904.1 0.043712 120 0-6825 0.9 4461.48 2880 1581,48 0'036305 ' ������N�� =��" ��m=���mu� �� MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 10 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) = 0.4 RATIONAL EQUATION: Q = CIA C = 0.85 A(area) = 0.75 TIME OF CONCENTRATION = ? TIME CA I INFLOW OUTFLOW STORAGE (min) _____________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 0.6375 5.65 1080.562 120 960.5625 0.022051 10 0.6375 4.4 1683 240 1443 0.033126 15 0.6375 3.7 2122.875 360 1762.875 0.040470 20 0.6375 3.25 2486.25 480 2006.25 0.046057 25 0.6375 2.85 2725.312 600 2125.312 0.048790 30 0.6375 2.6 2983.5 720 2263.5 0.051962 35 0.6375 2.35 3146.062 840 2306.062 0.052939 40 0.6375 2.2 3366 960 2406 0.055234+--0- 45 0.6375 2 3442.5 1080 2362.5 0.054235 50 0.6375 1.85 3538.125 1200 2338.125 0.053675 55 0.6375 1.75 3681.562 1320 2361.562 0.054214 60 0.6375 1.63 3740.85 1440 2300.85 0.052820 70 0.6375 1.44 3855.6 1680 2175.6 0.049944 80 0.6375 1.3 3978 1920 2058 0.047245 90 0.6375 1.2 4131 2160 1971 0.045247 100 0.6375 1.1 4207.5 2400 1807.5 0.041494 110 0.6375 1 4207.5 2640 1567.5 0.035984 120 0'6375 0.9 4131 2880 1251 0'028719 �� �� 0 ������N�� ~��" u�����mu� �� 1)E\1 Eucpbc� MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: WEBERG COMMENTS: 10 YEAR STORM MAXIMUM ALLOWABLE RELEASE (CFS) RATIONAL EQUATION: Q = CIA C = 0.85 A(area) = 1.94 TIME OF CONCENTRATION = ? TIME CA I INFLOW OUTFLOW STORAGE (min) (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) _____________________________________________________________________ 5 1.649 5.65 2795.055 330 2465.055 0.056589 10 1.649 4.4 4353.36 660 3693.36 0.084787 15 1.649 3.7 5491.17 990 4501.17 0.103332 20 1.649 3.25 6431.1 1320 5111.1 0.117334 25 1.649 2.85 7049.475 1650 5399.475 0.123954 30 1.649 2.6 7717.32 1980 5737.32 0.131710 35 1.649 2.35 8137.815 2310 5827.815 0.133788 40 1.649 2.2 8706.72 2640 6066.72 0.139272=-��' 45 1.649 2 8904.6 2970 5934.6 0.136239 50 1.649 1.85 9151.95 3300 5851.95 0.134342 55 1.649 1.75 9522.975 3630 5892.975 0.135284 60 1.649 1.63 9676.332 3960 5716.332 0.131228 70 1.649 1.44 9973.152 4620 5353.152 0.122891 80 1'649 1.3 10289.76 5280 5009.76 0.115008 90 1'649 1.2 10685.52 5940 4745.52 0.108942 100 1.649 1.1 10883.4 6600 4283.4 0.098333 110 1.649 1 10883.4 7260 3623.4 0.083181 120 1'649 0.9 10685.52 7920 2765.52 0.063487