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Home My WebLink About4TH FILING OF QUAIL HOLLOW SUBDIVISION - FINAL - 46-89B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT• N Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 303/226-4955 February 5, 1990 City of Fort Collins Planning Department 300 LaPorte Ave. Fort Collins, CO 80522 Attn: Glen Schlueter RE: QUAIL HOLLOW, FOURTH FILING Dear Glen: Quail Hollow, Fourth Filing consists of 50 single family lots lo- cated south of Drake Road, just east of Overland Trail. Total Land Area is 17.15 acres. Using the City's criteria for the basin; i.e. detain difference between developed and historical events; yields detention volumes of 75,000 cu.-ft. and 22,600 cu.-ft. for Ponds 1 & 2 respectively. These volumes allow for storage between the 100 year storm event and the 2 yr./100 yr. staged releases of the Pond Outlet Structures. These ponds; and their outlet structures; will be upgraded as future development occurs within the basins. The site has been divided into 2 basins. The larger basin, tributary to Pond #1 contains 12.15 acres of medium density residential development. The drainage channel within this basin will be improved to carry the 100 yr. developed flow plus upstream offsite flows. This area will drain into pond #1 via the existing drainage channel. Pond #1 will release at the 2 year historical rate during the 2 year event. During the 100 year storm event, the pond will release at less than the histori- cal 100 yr. rate due to a larger pond capacity than required. A fifty foot broadcrested weir will pass the offsite flow of 45.9 cfs. Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado (719) 598-4107 The smaller basin contains 3.82 acres. Discharge from the site flows easterly and will be intercepted by a drainage channel, discharging into Pond 2. This pond will detain the difference between the 2 yr./100 yr. developed and historical events. As buildout of Filings 5 & 6 occur, the pond capacity will be in- creased and release structures will be modified. Copies of the grading plan/offsite drainage facilities and cal- culating for sizing of facilities have been included for your reference. Should you have any questions or comments, please feel free to contact us. Sincerely, RBD, Inc. Cort Nickel, P.E. 5= RMINC Engineering Consultants • ('� CLIENT 1J )P� -E • JOBNO. PROJECT \U V a C 1, CALCULATIONS FOR MADE BY "` DATE Z 3 CHECKED BY DATE SHEET OF loo r._ + Tr'r) 1110 LH i ._.l __ r � I - L � Zs) II � � �4v I L 1 _ -} L ... _. �.i :. i I I l. _ ;_ 4 I i 3 �vv. } t t ' � t `r r ' r � -i-_ moo 5� ! ..... 1.. -t... j 1— a I ... �� I I }+i T I. I -t-- 1 G.. S I -i-�--r•- _ .! r - r '}' F I-i-- - -r -+--+ - { �Ljq� } I I i cis t csI°► c �.... �. } is �' -4 1-'}�--�-- 1 ...- _*_ 7 � ' � _� , , T � 14 .F.__l.. J �._ .... _I-_•}._! . L �.. F t I—'-�-t- �- - L _. L 4 r F-+ : CLIENT - IJ �t��... 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L -4. r_y r L T�DINC Engineering Consultants 0 is CLIENT JOB NO. PROJECT -CALCULATIONS FOR LA MADE BY DATE- CHECKED BY DATE -SHEET 01 OF 01 Yb ... .... .... IL Tt ... . t �J_ L LIL _4 I_— 4 ...... .. ... . ... . ....... -J, t..... . . . . . . . . . . . . . . . . ....... ..... . . . . . .......... . . . . . . . . . . 19.7 t- 7 4- - . .... .... . 4"LIL. L 4' t iL '7 7 is ... .. ...... .4 7—f.1 —4—T .... .... ... .. a�' T-1 .... .. .... .... I J-4- 11- - I .. . . .... ...... i -4 4 _ LAI rt- 4.- ZEE S 4 b13 7 ..... .. ... ............... _k . ........ . _4_ -4- . ... ...... .. 4 4- 4 _14 --- - - ---- _1 .. .. ...... ..... ... .... . .... ...... T _14-1-1- k4 MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: QUAIL HOLLOW FILING 4 COMMENTS:POND 1-2 YR. EVENT MAXIMUM ALLOWABLE RELEASE (CFS) = 2.14 RATIONAL EQUATION: Q = CIA C*Cf= 0.65 A(area) = 12.15 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) _____________________________________________________________________ (in/hr) (cu ft) (cu it) (cu it) (ac it) 5 7.8975 9 21323.25 642 20681.25 0.474776 10 7.8975 7.3 34591.05 1284 33307.05 0.764624 15 7.8975 6 42646.5 1926 40720.5 0.934814 20 7.8975 5.2 49280.4 2568 46712.4 1.072369 25 7.8975 4.6 54492.75 3210 51282.75 1.177289 30 7.8975 4.15 58994.32 3852 55142.32 1.265893 35 7.8975 3.8 63022.05 4494 58528.05 1.343619 40 7.8975 3.5 66339 5136 61203 1.405027 45 7.8975 3.25 69300.56 5778 63522.56 1.458277 50 7.8975 3 71077.5 6420 64657.5 1.484331 55 7.8975 2.8 72972.9 7062 65910.9 1.513106 60 7.8975 2.6 73920.6 7704 66216.6 1.520123 70 7.8975 2.3 76289.85 8988 67301.85 1.545037 80 7.8975 2.05 77711,4 10272 67439.4 1.548195 90 7.8975 1.85 78996.02 11556 67340.02 1.545914 100 7.8975 1.7 80554.5 12840 67714.5 1.554511 110 7.8975 1.55 80791.42 14124 66667.42 1.530473 120 7.8975 1.45 82449.9 15408 67041.9 1.539070 MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: QUAIL HOLLOW FILING 4 COMMENTS:POND 1-100 YR. EVENT UP TO WSE 5108.82 WITH 2 YR RELEA MAXIMUM ALLOWABLE RELEASE (CFS) = 2.14 RATIONAL EQUATION: Q = CIA C*Cf= 0.8125 A(area) = 12.15 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) ___________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 9.871875 9 26654.06 642 26012.06 0.597154 10 9.871875 7.3 43238.81 1284 41954.81 0.963149 15 9.871875 6 53308.12 1926 51382.12 1.179571 20 9.871875 5.2 61600.5 2568 59032.5 1.355199 25 9.871875 4.6 68115.93 3210 64905.93 1.490035 30 9.871875 4.15 73742.90 3852 69890.90 1.604474 35 9.871875 3.8 78777.56 4494 74283.56 1.705315 40 9.871875 3.5 82923.75 5136 77787.75 1.785761 45 9.871875 3.25 86625.70 5778 80847.70 1.856007 50 9.871875 3 88846.87 6420 82426.87 1.892260 55 9.871875 2.8 91216.12 7062 84154.12 1.931912 60 9.871875 2.6 92400.75 7704 84696.75 1.944369 70 9.871875 2.3 95362.31 8988 86374.31 1.982881 80 9'871875 2.05 97139'25 10272 86867.25 1.994197 90 9.871875 1.83 98620'03 11556 87064'03 1'998715 100 9.871875 1.7 100693.1 12840 87853.12 2.016830 110 9.871875 1.55 100989.2 14124 86865.28 1.994152 120 9.871875 1.45 103062.3 15408 87654.37 2.012267 NOTE: RELEASE AT 2 YEAR RATE UNTIL REACHING 07,439.4 CD -FT, (T=27.5 MIN,) ' MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: QUAIL HOLLOW FILING 4 COMMENTS:POND 2-2 YR. EVENT MAXIMUM ALLOWABLE RELEASE (CFS) = 0.76 RATIONAL EQUATION: Q = CIA C*Cf= 0.65 A(area) = 3.82 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) ____________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 2.483 9 6704.1 228 6476.1 0.148670 10 2.483 7.3 10875.54 456 10419.54 0.239199 15 2.483 6 13408.2 684 12724.2 0.292107 20 2.483 5.2 15493.92 912 14581.92 0.334754 25 2.483 4.6 17132.7 1140 15992.7 0.367141 30 2.483 4.15 18548.01 1368 17180.01 0.394398 35 2.483 3.8 19814.34 1596 18218.34 0.418235 40 2,483 3.5 20857.2 1824 19033.2 0.436942 45 2.483 3.25 21788.32 2052 19736.32 0.453083 50 2.483 3 22347 2280 20067 0.460674 55 2.483 2.8 22942.92 2508 20434,92 0.469121 60 2.483 2.6 23240.88 2736 20504.88 0.470727 70 2.483 2,3 23985.78 3192 20793.78 0.477359 90 2.483 2.05 24432.72 3648 20784.72 0.477151 90 2.483 1.85 24805.17 4104 20701.17 0.475233 100 2.483 1.7 25326'6 4360 20766.6 0.476735 110 2.483 1.55 25401.09 5016 20385'09 0.467977 � 120 2.483 1.45 25922.52 5472 20450.52 0.469479 MASS DIAGRAM METHOD for DETENTION VOLUMES PROJECT: QUAIL HOLLOW FILING 4 COMMENTS:POND2-100 YR EVENT UP TO WSE=9.67 MAXIMUM ALLOWABLE RELEASE (CFS) = 0.76 RATIONAL EQUATION: Q = CIA C*Cf= 0.8125 A(area) = 3.82 TIME OF CONCENTRATION = TIME CA I INFLOW OUTFLOW STORAGE (min) ___________________________________________________________________ (in/hr) (cu ft) (cu ft) (cu ft) (ac ft) 5 3.10375 9 8380.125 228 8152.125 0.187147 10 3.10375 7.3 13594.42 456 13138.42 0.301616 15 3.10375 6 16760.25 684 16076.25 0.369059 20 3.10375 5.2 19367.4 912 18455.4 0.423677 25 3.10375 4.6 21415.87 1140 20275.87 0.465470 30 3.10375 4.15 23185.01 1368 21817.01 0.500849 35 3.10375 3.8 24767.92 1596 23171.92 0.531954 40 3.10375 3.5 26071.5 1824 24247.5 0.056646 45 3.10375 3.25 27235.40 2052 25183.40 0.578131 50 3.10375 3 27933.75 2280 25653.75 0.588929 55 3.10375 2.8 28678.65 2508 26170.65 0.600795 60 3.10375 2.6 29051.1 2736 26315.1 0.604111 70 3.10375 2.3 29982.22 3192 26790.22 0.615018 80 3.10375 2.05 30540.9 3648 26892.9 0.617376 90 3.10375 1.85 31006.46 4104 26902.46 0.617595 100 3.10375 1.7 31658.25 4560 27098.25 0.622090 110 3.10375 1.55 31751.36 5016 26735.36 0.613759 120 3.10375 1.45 32403.15 5472 26931.15 0.618254 NOTE: RELEASE /T 2 YEAR RATE UNTIL BEACHING 20,784.72 CD -FT. (I=26,67JMZN,)