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HomeMy WebLinkAbout57 Development Permit 289R International SupplyDRAINAGE COMP UT A TIO NS for Grading Plan of Lot 2 -Block 1 Brown Addition 1.61 Acre Tract ROBERT STEVENSON LEAGUE College Station, Brazos County, Texas Prevared for Dillard Construction 13383 Highway 30 College Station, Texas 77845 Prevared by.· Garrett Engineering 4444 Carter Creek Parkway -Suite 108 Bryan, Texas 77802 Telephone: (409) 846-2688 *Revised: October, 1995 * DRAINAGE COMPUTATIONS for Grading Plan of Lot 2 -Block 1 Brown Addition 1.61 Acre Tract ROBERT STEVENSON LEAGUE College Station, Brazos County, Texas Prepa red for Dillard Construction 13383 Highway 30 College Station , Texas 77845 __ --; of Tc )':·. Prepared by.· , ........ , ... _, : ~v Garrett Engineering j~/' ~~-~· .... ' .. ~< 1 -\ 4444 Carter Creek Parkway -Suite 108 ff c-~...., ..... ~~---··RRE1 ~"·\ Bryan , Texas 77802 ~ ·· ·'.· ~ ......... ·g[§~ Telephone : (409) 846-2688 \ ~···~ ?J;/~/-'·i 11 Of. -~/S1f(.._.··.;..-f •1 s ............ ~ .:::-,,, S /QN ~\.. ~,.--'''~'"'''"""' *Revised: October, 1995 * DRAINAGE COMPUTATIONS for the Grading Plan of LOT 2, BLOCK 1 BROWN ADDITION 1.61 Acre Tract of Robert Stevenson League College Station, Brazos County, Texas *Revised October, 1995 * SUMMARY The project is situated off Graham Road in the Robert Stevenson League, College Station, Brazos County, Texas. The 1.61 acre tract composes Lot 2, Block 1 of the Brown Addition and will follow the attached revised grading plan. The total drainage area tributary to the project is 1.61 acres . The pre-development run-off coefficient was estimated to be 0.40. Taking into account the appropriate site improvements and paving, the post development coefficient is computed to be a value of 0.58 with a total breakdown of pervious to impervious area being 1.10 acres to 0.51 acres. A detention facility will be constructed in the south eastern portion of the property in keeping with the existing contours and as designated on the revised grading plan. Previously, the detention area was designed to be green space located in the same position. However, the revised grading plans calls for this area to be paved and will actually provide some additional capacity due to the following change. At the left side of the pavement area wall was used instead of the original sloped berm. The detention pond is designed to facilitate up to and including the 100-year storm event, and discharge at a rate less than the current pre-development peak discharge rate. The detention pond will intercept, store, and meter run-off from 0 .74 acres of the project. The run-off generated on the remaining 0.87 acres will "free-flow" across the project site. These report calculations are summarized according to the following methodology. Beginning on page 1, based on the total tributary drainage area of the project (being estimated at 1.61 acres), the pre- development run-off coefficient (being assumed at 0.40), and a minimum time of concentration of 10 minutes, the relative pre-development peak discharge rate ("Q") was determined. The Rational Method was utilized to compute the estimated peak pre-development discharge rates. The equation that represents the Rational Method is as follows: Q = CIA. "Q" is the peak discharge rate in cubic feet per second, "C" is the run-off coefficient, assumed to be 0.40 in the pre-development condition, "I" is the storm intensity in inches per hour, and "A" is the area of the drainage basin in acres. Computations on page 2 are based on the tributary area of 1.61 acres, the post-development run-off coefficient of 0.58 (being weighted according to the relative amounts of pervious and impervious surface area), a minimum time of concentration of 10 minutes, to yield the relative pre-development peak discharge rate ("Q") (assuming the same minimum time of concentration of 10 minutes). The Rational Method was again utilized to compute the estimated peak post-development discharge rates. The equation that represents the Rational Method is as follows: Q = CIA, where; "Q" is the peak discharge rate in cubic feet per second . The "C" variable is the run-off coefficient (In the post-development condition "C" is calculated to be 0 .58.) "I" represents the rainfall intensity in inches per hour, and similarly "A" is the area of the basin in acres . Comparison of the peak pre-development discharge rate to the post-development discharge rate is included in the report to aid the designer in establishing a preliminary "target" of detention volume required. This preliminary estimate is determined as the volume difference generated between the pre- development and post-development hydrographs. (See pages 9-11 for pre-development and post- development hydrographs.) Please note that the post-development hydrograph shown on these same graphs assumes no detention and reflects the "worst-case" scenario that all run-off is allowed to free-flow. Pages 3 and 4 provide information concerning the post-development run-off that is not routed through the detention facility ("free-flow") as well as the post-development run-off that is routed through the detention facility (which the bulk of the runoff load in this case) and metered through a weir. Page 5 and page 6 are tabulations of the pre-development and the post-development hydrographs based on the computations performed on page 1 and page 2. The post-development hydrograph assumes no detention to facilitate direct comparison in the pre-and post-development conditions. Page 7 and page 8 are tabulations of the post-development hydrograph for run-off directed through the detention facility and the post-development hydrograph for "free-flow" from the project site. Computations on page 4 determine the actual peak post-development "inflow" rate supplied to the proposed detention facility. From this "inflow" rate and the time of concentration (10 minutes minimum}, a hydrograph as tabulated on page 8 is derived . The hydrograph is triangular in shape and is based on the standard SCS unit hydrograph with time to peak set equal to the time of concentration and the total time base set at 3.00 times the time of concentration . Please note that a 30 minute total storm event duration was utilized exclusively throughout this report Having derived the preliminary volume requirements and "allowable peak" discharge rate, it is now possible to design the final detention facility and outlet control structure. Page 12 presents a data tabulation and a depth versus volume graph of the detention facility. The maximum depth of the pond was set a 1.18 feet with a volume capacity of approximately 7, 150 ft3 . (With the top of berm elevation at 315.50 ft. less flow line "out" of outlet control structure at 314.32 ft.: 315.50' -314.32' = 1.18' ). Page 13 supplies a tabulation and a rating curve for the proposed outlet control structure. A rectangular weir was chosen due to depth verses discharge ratio characteristics associated with this drainage scenario and headwater depth. An ultimate storage depth of 1.18 feet is available due to the physical geometry of the pond. However, even at the 100-year storm condition, runoff collected will only accumulate to a depth of about 0.5 ft. in the detention pond and be metered off site through a weir. The weir width was fixed at 3 .0 inches. The equation used to determine discharge was Q = CLH3/2 where "Q" is the discharge rate in cubic feet per second. "C" is the coefficient of discharge, in this case assumed to be set at 3.000. "L" is the width of the weir in feet, in this case assumed to be set at 3.0 inches. "H'' is the headwater depth in feet and ranges from 0 ft to a maximum of just over 1 ft. Page 14 presents a tabulation of the relationship between discharge from the detention facility and the dimensionless quantity 2S/t-O. Also presented is a Storage Indication Curve for the detention facility based on the aforementioned physical characteristics of the detention pond, storage volume, inflow hydrograph, and rating curve for the outlet structure . The storage indication curve as shown on page 12 is a graphical solution to the equation presented in the "Draina2e Policy And Desi2n Stanctards" as follows: 2s1 (11 + 12) + (----------------01) dt 2s2 = (-----------------+ Oi) dt The following pages present simulations of the 2, 5, 10, 25, 50, and 100 year storm events. The first page of each storm simulation represents the tabulated data for the storm event. The second page of each storm simulation represents the pre-development hydrograph, the post-development hydrograph (with no detention), the post-development hydrograph as routed through the detention pond, and post-development "free-flow" hydrograph for each storm event Total inflow I outflow hydrographs for the 2, 5, 10, 25, 50, and 100 year pre-development and post- development storm events. It can be determined from these same hydrographs that the post-development peak discharge rates do not exceed those peak pre-development discharge rates due to the incorporation of the detention facility in the post-development condition. Total post-development peak discharge rates from the detention pond outlet control structure and project site are kept within values less than the pre-development peak discharge rates by the incorporation of the proposed detention facility. The detention pond will provide the 0 .5 ft of "freeboard" required by the City of College Station and will be at only 25% of its volume capacity in the 100-Year Storm event Subsequent peak post-development discharge velocities also remain well within manageable limits. Determine Total Pre-Development Peak Storm Water Dischar e Rates Tributary Area ("A "): 1.61 Acres Pervious Area: 1.61 Acres Impervious Area : 0.00 Acres Run-Off Coefficient ("Cwt"): 0.40 Time Of Concentration ("T/c"): Woodlands: Low Elevation : High Elevation : Distance (Feet): Slope(% Grade): Velocity ("Vw"): Time : Pastures: Low Elevation: High Elevation: Distance (Feet): Slope (% Grade): Velocity ("Vp"): Time : Pavements: Low Elevation : High Elevation : Distance (Feet): Slope (% Grade): Velocity ("Vpave"): Time : Total Travel Time : Hourly Intensity Rates ("I"): 2-Year: 6 .33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11.15 100-Year: 11 .64 Peak Discharge Rate ("Q"): 2-Year: 4 .07 5-Year: 4.95 10-Year: 5.56 25-Year: 6 .35 50-Year: 7 .18 100-Year: 7.50 1 C= 0.40 C= 0.98 0 .00 0.00 0.00 0.00 0.00 Feet I Second 0 .00 Minutes 0.00 0.00 0.00 0.00 0 .00 Feet I Second 0.00 Minutes 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes 10.00 Minutes Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Determine Post-development Peak Storm Water Dischar e No Detention Tributary Area ("A"): 1.61 Acres Pervious Area : 1.10 Acres Impervious Area: 0.51 Acres Run-Off Coefficient ("Cwt"): 0.58 Time Of Concentration ("T/c"): 10 Minutes (Min) Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11.15 100-Year: 11 .64 C= 0.40 C= 0.98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Peak Discharge Rate ("Q"): 2-Year: 5.95 Cubic Feet I Second 5-Year: 7.23 Cubic Feet I Second 10-Year: 8.11 Cubic Feet I Second 25-Year: 9.27 Cubic Feet I Second 50-Year: 10.48 Cubic Feet I Second 100-Year: 10.94 Cubic Feet I Second Comparison Of Predevelop men t A nd Post-develo ment Pea k Dischar e Rates Predevelopment Post-Development 2-Year: 4 .07 Ft3/sec 5.95 Ft3/sec 5-Year: 4 .95 Ft3/sec 7.23 Ft3/sec 10-Year: 5.56 Ft3/sec 8.11 Ft3/sec 25-Year: 6.35 Ft3/sec 9 .27 Ft3/sec SO-Year: 7.18 Ft3/sec 10.48 Ft3/sec 100-Year: 7 .50 Ft3/sec 10.94 Ft3/sec Prelimin ary Det ermination Of Detenti on Pond Volume 2-Year: 5-Year: 10-Year: 25-Year: SO-Year : 100-Year: 1.87 Ft3/sec x (30 Min. x 60 Sec. I 2 ) = 2.28 Ft3/sec x (30 Min. x 60 Sec. I 2 ) = 2.55 Ft3/sec x (30 Min. x 60 Sec . I 2 ) = 2.92 Ft3/sec x (30 Min. x 60 Sec. I 2 ) = 3 .30 Ft3/sec x (30 Min. x 60 Sec . I 2 ) = 3.44 Ft3/sec x (30 Min . x 60 Sec. I 2 ) = 2 Increase 1.87 Ft3/sec 2.28 Ft3/sec 2.55 Ft3/sec 2 .92 Ft3/sec 3.30 Ft3/sec 3.44 Ft3/sec 1,684 Cubic 2,048 Cubic 2,299 Cubic 2,625 Cubic 2,968 Cubic 3,099 Cubic Feet Feet Feet Feet Feet Feet Determine Post-Development 11 Free-Flow 11 Peak Storm Water Dischar e Tributary Area ("A"): 0.87 Acres Pervious Area : 0.87 Acres Impervious Area: 0.00 Acres Run-Off Coefficient ("Cwt"): 0.40 Time Of Concentration ("T/c"): 10 Minutes (Min) Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11 .15 100-Year: 11.64 Peak Discharge Rate ("Q"): 2-Year: 2.20 5-Year: 2.68 10-Year: 3 .00 25-Year: 3.43 50-Year: 3.88 100-Year: 4.05 3 C= 0.40 C= 0.98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Seco nd Cubic Feet I Second Cubic Feet I Seco nd Cubic Feet I Second Cubic Feet I Second Tributary Area ("A"): 0.74 Acres Pervious Area: 0.24 Acres C= 0.40 Impervious Area: 0.50 Acres C= 0 .98 Run-Off Coefficient ("Cwt"): 0 .66 Time Of Concentration ("T/c"): 1 O Minutes (Min) 0 .00 Hourly Intensity Rates ("I"): 2-Year: 6.33 Inches I Hour 5-Year: 7.69 Inches I Hour 10-Year: 8.63 Inches I Hour 25-Year: 9.86 Inches I Hour 50-Year: 11.15 Inches I Hour 100-Year: 11.64 Inches I Hour Peak Discharge Rate ("Q"): 2-Year: 3.10 Cubic Feet I Second 5-Year: 3.77 Cubic Feet I Second 10-Year: 4.23 Cubic Feet I Second 25-Year: 4.84 Cubic Feet I Second 50-Year: 5.47 Cubic Feet I Second 100-Year: 5.71 Cubic Feet I Second 4 Pre-Development Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year {Minutes} Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.41 0.50 0.56 0.64 0.72 0.75 2 0.81 0.99 1.11 1.27 1.44 1.50 3 1.22 1.49 1.67 1.91 2.15 2.25 4 1.63 1.98 2.22 2.54 2.87 3.00 5 2.04 2.48 2.78 3.18 3.59 3.75 6 2.44 2.97 3.34 3.81 4.31 4.50 7 2.85 3.47 3.89 4.45 5.03 5.25 8 3.26 3.96 4.45 5.08 5.74 6.00 9 3.67 4.46 5.00 5.72 6.46 6.75 Peak=> I 10 4.07 4.95 5.56 6.35 7.18 7.50 11 3.87 4.71 5.28 6.03 6.82 7.12 12 3.67 4.46 5.00 5.72 6.46 6.75 13 3.46 4.21 4.73 5.40 6.10 6.37 14 3.26 3.96 4.45 5.08 5.74 6.00 15 3.06 3.72 4.17 4.76 5.38 5.62 16 2.85 3.47 3.89 4.45 5.03 5.25 17 2.65 3.22 3.61 4.13 4.67 4.87 18 2.44 2.97 3.34 3.81 4.31 4.50 19 2.24 2.72 3.06 3.49 3.95 4.12 20 2.04 2.48 2.78 3.18 3.59 3.75 21 1.83 2.23 2.50 2.86 3.23 3.37 22 1.63 1.98 2.22 2.54 2.87 3.00 23 1.43 1.73 1.95 2.22 2.51 2.62 24 1.22 1.49 1.67 1.91 2.15 2.25 25 1.02 1.24 1.39 1.59 1.79 1.87 26 0.81 0.99 1.11 1.27 1.44 1.50 27 0.61 0.74 0.83 0.95 1.08 1.12 28 0.41 0.50 0.56 0.64 0.72 0.75 29 0.20 0.25 0.28 0.32 0.36 0.37 30 0.00 0.00 0.00 0.00 0.00 0.00 5 Post-Development Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.59 0.72 0.81 0.93 1.05 1.09 2 1.19 1.45 1.62 1.85 2.10 2.19 3 1.78 2.17 2.43 2.78 3.14 3.28 4 2.38 2.89 3.25 3.71 4.19 4.38 5 2.97 3.61 4.06 4.63 5.24 5.47 6 3.57 4.34 4.87 5.56 6.29 6.56 7 4.16 5.06 5.68 6.49 7.33 7.66 8 4.76 5.78 6.49 7.41 8.38 8.75 9 5.35 6.51 7.30 8.34 9.43 9.84 Peak=> I 10 5.95 7.23 8.11 ~.27 10.48 10.94 11 5.65 6.87 7.71 8.80 9.95 10.39 12 5.35 6.51 7.30 8.34 9.43 9.84 13 5.05 6.15 6.90 7.88 8.91 9.30 14 4.76 5.78 6.49 7.41 8.38 8.75 15 4.46 5.42 6.09 6.95 7.86 8.20 16 4.16 5.06 5.68 6.49 7.33 7.66 17 3.86 4.70 5.27 6.02 6.81 7.11 18 3.57 4.34 4.87 5.56 6.29 6.56 19 3.27 3.98 4.46 5.10 5.76 6.02 20 2.97 3.61 4.06 4.63 5.24 5.47 21 2.68 3.25 3.65 4.17 4.71 4.92 22 2.38 2.89 3.25 3.71 4.19 4.38 23 2.08 2.53 2.84 3.24 3.67 3.83 24 1.78 2.17 2.43 2.78 3.14 3.28 25 1.49 1.81 2.03 2.32 2.62 2.73 26 1.19 1.45 1.62 1.85 2.10 2.19 27 0.89 1.08 1.22 1.39 1.57 1.64 28 0.59 0.72 0.81 0.93 1.05 1.09 29 0.30 0.36 0.41 0.46 0.52 0.55 30 0.00 0.00 0.00 0.00 0.00 0.00 6 Post-Development "Free-Flow" Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0 .00 0.00 0.00 0.00 0 .00 0.00 1 0.22 0.27 0.30 0.34 0 .39 0.41 2 0.44 0 .54 0.60 0.69 0 .78 0.81 3 0 .66 0 .80 0 .90 1.03 1.16 1.22 4 0 .88 1.07 1.20 1.37 1.55 1.62 5 1.10 1.34 1.50 1.72 1.94 2 .03 6 1.32 1.61 1.80 2.06 2.33 2.43 7 1.54 1.87 2.10 2.40 2.72 2.84 8 1.76 2.14 2.40 2.75 3.10 3 .24 9 1.98 2.41 2.70 3.09 3.49 3.65 Peak=> 10 2.20 2.68 3 .00 3.43 3.88 4.05 11 2.09 2.54 2.85 3 .26 3 .69 3 .85 12 1.98 2.41 2 .70 3.09 3.49 3 .65 13 1.87 2 .28 2.55 2.92 3 .30 3 .44 14 1.76 2 .14 2 .40 2 .75 3.10 3 .24 15 1.65 2.01 2.25 2 .57 2.91 3 .04 16 1.54 1.87 2 .10 2.40 2.72 2.84 17 1.43 1.74 1.95 2.23 2.52 2.63 18 1.32 1.61 1.80 2.06 2.33 2.43 19 1.21 1.47 1.65 1.89 2.13 2 .23 20 1.10 1.34 1.50 1.72 1.94 2 .03 21 0.99 1.20 1.35 1.54 1.75 1.82 22 0.88 1.07 1.20 1.37 1.55 1.62 23 0 .77 0.94 1.05 1.20 1.36 1.42 24 0.66 0 .80 0.90 1.03 1.16 1.22 25 0.55 0 .67 0.75 0 .86 0 .97 1.01 26 0.44 0 .54 0.60 0 .69 0 .78 0 .81 27 0 .33 0.40 0.45 0 .51 0 .58 0 .61 28 0 .22 0 .27 0 .30 0.34 0.39 0.41 29 0 .11 0 .13 0 .15 0 .17 0 .19 0 .20 30 0 .00 0 .00 0.00 0 .00 0 .00 0 .00 7 Post-Development Flow Routed Through Detention Pond Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.31 0.38 0.42 0.48 0.55 0.57 2 0.62 0.75 0.85 0.97 1.09 1.14 3 0.93 1.13 1.27 1.45 1.64 1.71 4 1.24 1.51 1.69 1.93 2.19 2.28 5 1.55 1.89 2.12 2.42 2.73 2.85 6 1.86 2.26 2.54 2.90 3.28 3.42 7 2.17 2.64 2.96 3.39 3.83 4.00 8 2.48 3.02 3.39 3.87 4.37 4.57 9 2.79 3.40 3.81 4.35 4.92 5.14 Peak=> I 10 3.10 3.77 4.23 4.84 5.47 5.71 11 2.95 3.58 4.02 4.59 5.19 5.42 12 2.79 3.40 3.81 4.35 4.92 5.14 13 2.64 3.21 3.60 4.11 4.65 4.85 14 2.48 3.02 3.39 3.87 4.37 4.57 15 2.33 2.83 3.18 3.63 4.10 4.28 16 2.17 2.64 2.96 3.39 3.83 4.00 17 2.02 2.45 2.75 3.14 3.55 3.71 18 1.86 2.26 2.54 2.90 3.28 3.42 19 1.71 2.07 2.33 2.66 3.01 3.14 20 1.55 1.89 2.12 2.42 2.73 2.85 21 1.40 1.70 1.91 2.18 2.46 2.57 22 1.24 1.51 1.69 1.93 2.19 2.28 23 1.09 1.32 1.48 1.69 1.91 2.00 24 0.93 1.13 1.27 1.45 1.64 1.71 25 0.78 0.94 1.06 1.21 1.37 1.43 26 0.62 0.75 0.85 0.97 1.09 1.14 27 0.47 0.57 0.64 0.73 0.82 0.86 28 0.31 0.38 0.42 0.48 0.55 0.57 29 0.16 0.19 0.21 0.24 0.27 0.29 30 0.00 0.00 0.00 0.00 0.00 0.00 8 6 .00 ... Cl> 5.00 Q.. -Cl> Cl> 4 .00 ..... o-·-"O .0 c ::J 0 3.00 0 0 -Cl> Cl> (,/) O> 2.00 ... 0 .t: 0 I/) l.00 c 0.00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 2-Year Storm Event 5 10 15 20 25 Time (Minutes) 30 ---Pre-Development Hydrograph ---Total Po st-Development Hydrograph Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 5-Year Storm Event 8 .00 ----~---~---~----...-----.....-------, ~ 7.00 ..__----+-----IP._..,_----+----1-----+------; Q.. -; 6.00 ..__----+---#--+---~--+----1-----+------; Cl> ..... . 2 ~ 5.00 .0 c 8 8 4.00 .,__ ___ ---+-.1.__~,£---+------""-oe-+-----".....--1-----+------; ....... Cl> 8, (,/) 3.00 .,__ __ _,.-+-..,,C..----+------+---....:::"""=:--1---":---+------; 0 .t: 2.00 ...__ _ ___,_--,tf!.:..+-----+-----+----t---~;;::----.31io,d-----1 ~ c l.00...__--hL---+-----+-----+----t--------t='""""7"~--1 0.00 ~----+-----+-----t----..... ---+-----at 0 5 10 15 20 25 Time (Minutes) ---Pre -Devel o pment Hydrograph ---Post-Development Outflow Hydrograph Without Detention 9 30 9 .00 ... 8.00 Cl) 0.. -7.00 Q) Q) 6 .00 LL. o-·-"O .g c 5.00 0 0 4 .00 _o Cl)~ O> 3 .00 ... 0 s:; 2 .00 0 Cl) i5 l.00 0 .00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 10-Year Storm Event 5 10 15 20 25 Time (Minutes) 30 ---Pre -Development Hydrograph ----Post-Development Outflow Hydrograph With o ut Detent io n 10.00 ... 9.00 Cl) 0.. 8 .00 '$ Q) 7.00 LL. o-6 .00 ·-"O .0 c :::J 0 5.00 0 0 -Q) 4 .00 Q) V> O> ... 3 .00 0 s:; 0 2 .00 Cl) i5 l.00 0 .00 0 Total Pre-Development Vs. Total Post-Development (N o Detention) Peak Discharge Rates 25-Year Storm Event 5 10 15 20 25 Time (Minutes) 30 ----Pre -Dev elopme nt Hydr o graph ----Post -Development Outflow Hydrograph With out Detention 10 ... Q) Q.. -Q) Q) u.. o-·-"O ..0 c ::J 0 0 0 -Q) Q) Cl) O> ... 0 ..c 0 II) i:5 ... Q) Q.. -Q) Q) u.. o-·-"O ..0 c ::J 0 0 0 -Q) Q) Cl) O> ... 0 ..c 0 II) i:5 12.00 10 .00 8.00 6.00 4.00 2.00 0.00 0 Total Pre-Development Vs. Total Post-Development (N o Detention) Peak Discharge Rates 50-Year Storm Even t 5 10 15 20 25 Time (Minutes) 30 Pre-Dev elopment Hydrograph Post -Development Outflow Hydrograph Wit h o ut Detention 12.00 10 .00 8.00 6.00 4.00 2.00 0.00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 100-Year Storm Eve nt 5 10 15 20 25 Time (Minutes) ----Pre-De v el o pment Hydrograph ----Post-Development Outflow Hydrograph Without Detention 11 30 Detention Pond Deoth Vs. Volume ~ Cl> LL. 1.20 l.00 0 .80 Elevation Depth Volume (Feet) (Ft3) 314.32 0.00 0 314.62 0.30 495 314.75 0.43 1,103 315.00 0.68 2,598 315.25 0.93 4,615 315.50 1.18 7,143 Detention Pond Depth Vs. Volume ;; 0 .60 ~---+---~<----+----t----t----t----t-----l a. Cl> a 0 .40 0 .20 0 .00 0 l ,000 2 ,000 3 ,000 4 ,000 5 ,000 6 ,000 7 ,000 8 ,000 Detention Pond Volume (Cubic Feet) 12 Rating Curve For Outlet Control Structure Weir Length(L): 3.00 De th Vs. Volume Elevation Depth Discharge (Feet) Ft3/Sec 314.32 0.00 0.00 314.62 0.30 1.48 314.75 0.43 2.54 315 .00 0.68 5.05 315.25 0.93 8.07 315.50 1.18 11.54 Rating Curve For Outlet Control Structure Depth Vs. l.20 l.00 0.80 ~ Q) u... -;; 0 .60 a. Q) a 0 .40 0.00 2.00 Volume 4.00 6.00 8.00 10.00 Discharge (Cubic Feet Per Second) 13 12.00 I Storage Indication Curve Depth Storage Discharge 2s/t 2s/t+O (Feet) (Ft3) (Ft3/Sec) (Ft3/Sec) (Ft3/Sec) 0.00 0 0.00 0.00 0.00 0.30 495 1.48 16.50 17.98 0.43 1,103 2.54 36.77 39.30 0.68 2,598 5.05 86 .60 91.65 0.93 4,615 8.07 153.83 161.91 1.18 7,143 11 .54 238.10 249 .64 Storage Indication Curve 12.00 10 .00 -"O c 0 8.00 0 ~ ... Q) Q., -Q) Q) ..... 6 .00 0 :0 :J (.) -Q) C> ... 0 ..c 4.00 ~ 0 2 .00 0 .00 0 .00 50.00 100 .00 150.00 200.00 250 .00 2s/t+O (Cubic Feet Per Second) 14 Inflow I Outflow Simulation 2-Year Storm Event Time Inflow 11+ 12 2s/t-O 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.31 0.31 0.26 0.31 0.03 0.02 314.34 0.42 2 0.62 0.93 0.99 1.19 0.10 0.05 314.37 0.66 3 0.93 1.55 2.13 2.55 0.21 0.08 314.40 0.86 4 1.24 2.17 3.59 4.30 0.35 0.12 314.44 1.02 5 1.55 2.79 5.33 6.38 0.53 0.15 314.47 1.16 6 1.86 3.41 7.31 8.75 0.72 0.19 314.51 1.29 7 2.17 4.03 9.47 11.34 0.93 0.22 314.54 1.41 8 2.48 4.65 11.80 14.13 1.16 0.26 314.58 1.52 9 2.79 5.27 14.27 17.08 1.40 0.29 314.61 1.62 10 3.10 5.89 16.99 20.16 1.59 0.31 314.63 1.68 11 2.95 6.05 19.58 23.04 1.73 0.33 314.65 1.73 12 2.79 5.74 21.63 25.32 1.84 0.35 314.67 1.77 13 2.64 5.43 23.20 27.06 1.93 0.36 314.68 1.80 14 2.48 5.12 24.34 28.32 1.99 0.37 314.69 1.81 15 2.33 4.81 25.08 29.15 2.03 0.37 314.69 1.83 16 2.17 4.50 25.47 29.58 2.05 0.37 314.69 1.83 17 2.02 4.19 25.54 29.66 2.06 0.37 314.69 1.83 18 1.86 3.88 25.32 29.42 2.05 0.37 314.69 1.83 19 1.71 3.57 24.85 28.89 2.02 0.37 314.69 1.82 20 1.55 3.26 24.14 28.11 1.98 0.36 314.68 1.81 21 1.40 2.95 23.23 27.09 1.93 0.36 314.68 1.80 22 1.24 2.64 22.12 25.87 1.87 0.35 314.67 1.78 23 1.09 2.33 20.85 24.45 1.80 0.34 314.66 1.75 24 0.93 2.02 19.42 22.87 1.72 0.33 314.65 1.73 25 0.78 1.71 17.86 21.13 1.64 0.32 314.64 1.70 26 0.62 1.40 16.17 19.26 1.54 0.31 314.63 1.67 27 0.47 1.09 14.42 17.26 1.42 0.29 314.61 1.62 28 0.31 0.78 12.69 15.19 1.25 0.27 314.59 1.55 29 0.16 0.47 11.00 13.16 1.08 0.24 314.56 1.48 30 0.00 0.16 9.32 11.15 0.92 0.22 314.54 1.40 15 Inflow/Outflow Simulation 2-Year Storm Event 6.00 " • " • " • .. • " 5.00 • " " • • " " I " I I " -"O 4 .00 c 0 0 I " ' I Q) Cl) " • .. .... Q) I " ll.. I " -Q) • " Q) 3 .00 I.&. 0 " :0 I " j " (.) -I " ~ 0 " I " ~ 2 .00 j 0 I I I . ...... I ...... ' ...... ' ...... ' ' 1.00 0 .00 0 5 10 15 20 25 30 Time (Minutes) Pre -----Post-Post--• -• -• Post- Developme Developme Developme Developme nt nt Outflow nt Outflow nt "Free- Hydrograph Hydrograph With Flow" Without Detention Dete nti on 16 Inflow I Outflow Simulation 5-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0.00 0.00 0.00 0 .00 0.00 0 .00 314 .32 0.00 1 0 .38 0 .38 0.32 0 .38 0.03 0 .02 314.34 0.45 2 0 .75 1.13 1.21 1.45 0.12 0.06 314.38 0.71 3 1.13 1.89 2 .59 3.10 0.25 0.09 314.41 0.91 4 1.51 2.64 4.37 5.23 0.43 0.13 314.45 1.09 5 1.89 3.40 6.49 7.76 0.64 0.17 314.49 1.24 6 2 .26 4.15 8.89 10.64 0 .87 0.21 314.53 1.38 7 2.64 4 .90 11.52 13 .79 1.13 0 .25 314.57 1.50 8 3 .02 5 .66 14.35 17.18 1.41 0 .29 314.61 1.62 9 3.40 6.41 17.53 20.77 1.62 0.32 314.64 1.69 10 3 .77 7 .17 21.08 24.70 1.81 0 .34 314.66 1.76 11 3 .58 7.36 24.44 28.43 2.00 0 .37 314.69 1.82 12 3.40 6 .98 27.12 31.42 2 .15 0 .38 314.70 1.86 13 3 .21 6.60 29 .20 33 .73 2.26 0.40 314.72 1.89 14 3.02 6.22 30.74 35.43 2.35 0.41 314.73 1.92 15 2.83 5.85 31.78 36.59 2.40 0.41 314.73 1.93 16 2 .64 5.47 32.38 37.25 2.44 0.42 314.74 1.94 17 2.45 5.09 32.58 37.47 2.45 0.42 314.74 1.94 18 2 .26 4 .72 32.42 37 .29 2.44 0.42 314 .74 1.94 19 2 .07 4 .34 31 .93 36.76 2.41 0.42 314 .74 1.93 20 1.89 3 .96 31 .16 35 .90 2.37 0.41 314.73 1.92 21 1.70 3 .58 30 .12 34.74 2.31 0.40 314.72 1.91 22 1.51 3 .21 28 .84 33.33 2.24 0.40 314.72 1.89 23 1.32 2.83 27 .36 31.67 2.16 0 .39 314.71 1.86 24 1.13 2.45 25.68 29 .81 2.07 0 .37 314.69 1.84 25 0.94 2.07 23 .82 27 .75 1.96 0.36 314.68 1.81 26 0.75 1.70 21.81 25 .52 1.85 0.35 314.67 1.77 27 0.57 1.32 19.66 23 .13 1.73 0.33 314.65 1.73 28 0.38 0 .94 17 .39 20 .61 1.6 1 0 .32 314 .64 1.69 29 0 .19 0 .57 15 .00 17.95 1.48 0.30 314.62 1.64 30 0.00 0 .19 12 .69 15 .19 1.25 0 .27 314.59 1.55 17 1J c 0 8.00 7.00 6 .00 g 5.00 en a; Q., 'i Cl> u.. 4.00 0 :.0 :J 0 -~ 3.00 :g 0 2 .00 1.00 0 .00 0 Inflow/Outflow Simulation 5-Year Storm Event 5 Pre-- Developme nt Hydrograph - I I I I -- I I I I I 10 ' .. .. .. 15 Time (Minutes) Post- Developme nt Outflow Hydrograph Without Detention 18 20 25 Post -.... -... Developme nt Outflow With Detention 30 Post - Developme nt "Free- Flow" Inflow I Outflow Simulation 10-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.42 0.42 0.35 0.42 0.03 0.02 314.34 0.47 2 0.85 1.27 1.36 1.62 0.13 0.06 314.38 0.74 3 1.27 2.12 2.90 3.47 0.29 0.10 314.42 0.95 4 1.69 2.96 4.90 5.87 0.48 0.14 314.46 1.13 5 2.12 3.81 7.28 8.71 0.72 0.19 314.51 1.29 6 2.54 4.66 9.97 11.94 0.98 0.23 314.55 1.43 7 2.96 5.50 12.93 15.48 1.27 0.27 314.59 1.56 8 3.39 6.35 16.20 19.28 1.54 0.31 314.63 1.67 9 3.81 7.20 19.90 23.39 1.75 0.34 314.66 1.74 10 4.23 8.05 24.00 27.94 1.97 0.36 314.68 1.81 11 4.02 8.26 27.88 32.25 2.19 0.39 314.71 1.87 12 3.81 7.83 30.99 35.71 2.36 0.41 314.73 1.92 13 3.60 7.41 33.42 38.40 2.49 0.42 314.74 1.96 14 3.39 6.99 35.22 40.40 2.59 0.44 314.76 1.98 15 3.18 6.56 36.47 41.79 2.66 0.44 314.76 2.00 16 2.96 6.14 37.22 42.61 2.70 0.45 314.77 2.01 17 2.75 5.72 37.51 42.94 2.71 0.45 314.77 2.01 18 2.54 5.29 37.39 42.81 2.71 0.45 314.77 2.01 19 2.33 4.87 36.91 42.26 2.68 0.45 314.77 2.00 20 2.12 4.45 36.08 41.35 2.64 0.44 314.76 1.99 21 1.91 4.02 34.95 40.10 2.58 0.43 314.75 1.98 22 1.69 3.60 33.55 38.55 2.50 0.43 314.75 1.96 23 1.48 3.18 31.91 36.72 2.41 0.42 314.74 1.93 24 1.27 2.75 30.04 34.66 2.31 0.40 314.72 1.91 25 1.06 2.33 27.99 32.37 2.19 0.39 314.71 1.87 26 0.85 1.91 25.75 29.89 2.07 0.38 314.70 1.84 27 0.64 1.48 23.36 27.23 1.94 0.36 314.68 1.80 28 0.42 1.06 20.82 24.41 1.80 0.34 314.66 1.75 29 0.21 0.64 18.15 21.45 1.65 0.32 314.64 1.70 30 0.00 0.21 15.37 18.36 1.50 0.30 314.62 1.65 19 9.00 8 .00 7.00 ~ c 6 .00 0 0 Q) V) a; 0.. 5.00 'i Q) u.. 0 :0 :::J 4 .00 (.) -~ = :::J 3.00 0 2.00 1.00 0.00 Inflow/Outflow Simulation 10-Year Storm Event 0 5 Pre -- Deve lopme nt Hydrograph - I I - I I I I - I I I ... 10 ... ... ... ' ... ' ' ' 15 Time (Minutes) Post - Developme nt Outflow Hydrograph With o ut Det e nti on 20 20 25 Post -................ Developme nt Outflow With Detention 30 Post - Developme nt "Free- Flow · Inflow I Outflow Simulation 25-Year Storm Event Time Inflow 11+ 12 2slt-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.48 0.48 0.40 0.48 0.04 0.03 314.35 0.49 2 0.97 1.45 1.55 1.85 0.15 0.07 314.39 0.77 3 1.45 2.42 3.32 3.97 0.33 0.11 314.43 0.99 4 1.93 3.39 5.60 6.70 0.55 0.16 314.48 1.18 5 2.42 4.35 8.31 9.95 0.82 0.20 314.52 1.35 6 2.90 5.32 11.39 13.63 1.12 0.25 314.57 1.50 7 3.39 6.29 14.77 17.68 1.45 0.30 314.62 1.63 8 3.87 7.25 18.66 22.02 1.68 0.33 314.65 1.71 9 4.35 8.22 23.04 26.89 1.92 0.36 314.68 1.79 10 4.84 9.19 27.86 32.23 2.19 0.39 314.71 1.87 11 4.59 9.43 32.41 37.29 2.44 0.42 314.74 1.94 12 4.35 8.95 36.09 41.36 2.64 0.44 314.76 1.99 13 4.11 8.46 38.97 44.55 2.79 0.46 314.78 2.03 14 3.87 7.98 41.14 46.95 2.90 0.47 314.79 2.06 15 3.63 7.50 42.67 48.64 2.99 0.48 314.80 2.08 16 3.39 7.01 43.61 49.68 3.04 0.48 314.80 2.09 17 3.14 6.53 44.03 50.14 3.06 0.49 314.81 2.09 18 2.90 6.05 43.96 50.07 3.05 0.49 314.81 2.09 19 2.66 5.56 43.47 49.52 3.03 0.48 314.80 2.09 20 2.42 5.08 42.59 48.55 2.98 0.48 314.80 2.08 21 2.18 4.59 41.35 47.18 2.92 0.47 314.79 2.06 22 1.93 4.11 39.79 45.46 2.83 0.46 314.78 2.04 23 1.69 3.63 37.95 43.42 2.74 0.45 314.77 2.02 24 1.45 3.14 35.85 41.09 2.62 0.44 314.76 1.99 25 1.21 2.66 33.51 38.51 2.50 0.43 314.75 1.96 26 0.97 2.18 30.97 35.69 2.36 0.41 314.73 1.92 27 0.73 1.69 28.25 32.66 2.21 0.39 314.71 1.88 28 0.48 1.21 25.36 29.46 2.05 0.37 314.69 1.83 29 0.24 0.73 22.32 26.08 1.88 0.35 314.67 1.78 30 0.00 0.24 19.15 22.56 1.71 0.33 314.65 1.72 21 Inflow/Outflow Simulation 25-Year Storm Event 10.00 ' 9.00 I ' I ' ' • ' 8 .00 I I ' I ' I ' 7.00 I ' -'O • c ' 0 I "' 0 G> en 6.00 -G> Q... -G> G> 5 .00 u.. 0 :0 ::::J 0 -4 .00 ~ 0 =§ 0 3 .00 2 .00 1.00 0.00 0 5 10 15 20 25 30 Time (Minutes) Pre-----Post-Post -.... -. --Post - Developme Developme Developme Developme nt nt Outflow nt Outflow nt 'Free- Hydrograph Hydrograph With Flow' Without Detention Detention 22 Inflow I Outflow Simulation 50-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.55 0.55 0.46 0.55 0.04 0.03 314.35 0.51 2 1.09 1.64 1.75 2.10 0.17 0.07 314.39 0.80 3 1.64 2.73 3.75 4.49 0.37 0.12 314.44 1.03 4 2.19 3.83 6.33 7.57 0.62 0.17 314.49 1.23 5 2.73 4.92 9.40 11.25 0.93 0.22 314.54 1.41 6 3.28 6.01 12.88 15.41 1.27 0.27 314.59 1.56 7 3.83 7.11 16.83 19.98 1.58 0.31 314.63 1.68 8 4.37 8.20 21.37 25.03 1.83 0.35 314.67 1.76 9 4.92 9.29 26.45 30.66 2.11 0.38 314.70 1.85 10 5.47 10.39 32.00 36.83 2.41 0.42 314.74 1.93 11 5.19 10.66 37.26 42.66 2.70 0.45 314.77 2.01 12 4.92 10.11 41.53 47.38 2.92 0.47 314.79 2.06 13 4.65 9.57 44.89 51.10 3.10 0.49 314.81 2.10 14 4.37 9.02 47.43 53.91 3.24 0.51 314.83 2.13 15 4.10 8.47 49.24 55.91 3.33 0.52 314.84 2.15 16 3.83 7.93 50.38 57.17 3.39 0.52 314.84 2.17 17 3.55 7.38 50.92 57.76 3.42 0.52 314.84 2.17 18 3.28 6.83 50.91 57.75 3.42 0.52 314.84 2.17 19 3.01 6.29 50.40 57.19 3.40 0.52 314.84 2.17 20 2.73 5.74 49.45 56.14 3.34 0.52 314.84 2.16 21 2.46 5.19 48.10 54.65 3.27 0.51 314.83 2.14 22 2.19 4.65 46.38 52.75 3.18 0.50 314.82 2.12 23 1.91 4.10 44.34 50.48 3.07 0.49 314.81 2.10 24 1.64 3.55 41.99 47.89 2.95 0.48 314.80 2.07 25 1.37 3.01 39.38 45.00 2.81 0.46 314.78 2.04 26 1.09 2.46 36.52 41.84 2.66 0.44 314.76 2.00 27 0.82 1.91 33.44 38.43 2.49 0.43 314.75 1.96 28 0.55 1.37 30.18 34.81 2.31 0.40 314.72 1.91 29 0.27 0.82 26.75 31.00 2.13 0.38 314.70 1.85 30 0.00 0.27 23.17 27.02 1.93 0.36 314.68 1.80 23 Inflow/Outflow Simulation 50-Year Storm Event 12.00 • 10.00 ' ' • ' • ' • ' • ' ' ........ • ' "O 8.00 • c 0 • 0 • ' G> en • ' ... ' G> • 0.. ' -• G> ' G> • ' LL. 6.00 ' 0 • ' :.0 ' ;:, (.) • -' ~ • ' 0 • ' =§ 4.00 • 0 • . ' • . . ' ' ' . . . • ' ' . . ' ' 2.00 ' . ' ' ' ' ' ' 0.00 0 5 10 15 20 25 30 Time (Minutes) Pre--. . . Post-Post---------Post - Developme Developme Developme Developme nt nt Outflow nt Outflow nt "Free- Hydrograph Hydr ograph With Flow· Without Detention Detention 24 Inflow I Outflow Simulation 100-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.57 0.57 0.48 0.57 0.05 0.03 314.35 0.52 2 1.14 1.71 1.83 2.19 0.18 0.07 314.39 0.81 3 1.71 2.85 3.91 4.68 0.39 0.12 314.44 1.05 4 2.28 4.00 6.61 7.91 0.65 0.17 314.49 1.25 5 2.85 5.14 9.81 11.74 0.97 0.23 314.55 1.43 6 3.42 6.28 13.44 16.09 1.32 0.28 314.60 1.58 7 4.00 7.42 17.62 20.86 1.62 0.32 314.64 1.69 8 4.57 8.56 22.41 26.18 1.89 0.35 314.67 1.78 9 5.14 9.70 27.75 32.11 2.18 0.39 314.71 1.87 10 5.71 10.84 33.59 38.60 2.50 0.43 314.75 1.96 11 5.42 11.13 39.13 44.72 2.80 0.46 314.78 2.03 12 5.14 10.56 43.62 49.69 3.04 0.48 314.80 2.09 13 4.85 9.99 47.16 53.60 3.22 0.50 314.82 2.13 14 4.57 9.42 49.84 56.58 3.37 0.52 314.84 2.16 15 4.28 8.85 51.76 58.69 3.47 0.53 314.85 2.18 16 4.00 8.28 52.97 60.03 3.53 0.54 314.86 2.20 17 3.71 7.71 53.55 60.68 3.56 0.54 314.86 2.20 18 3.42 7.13 53.56 60.69 3.56 0.54 314.86 2.20 19 3.14 6.56 53.05 60.13 3.54 0.54 314.86 2.20 20 2.85 5.99 52.08 59.05 3.48 0.53 314.85 2.19 21 2.57 5.42 50.68 57.50 3.41 0.52 314.84 2.17 22 2.28 4.85 48.90 55.53 3.32 0.51 314.83 2.15 23 2.00 4.28 46.78 53.18 3.20 0.50 314.82 2.13 24 1.71 3.71 44.34 50.49 3.07 0.49 314.81 2.10 25 1.43 3.14 41.62 47.48 2.93 0.47 314.79 2.06 26 1.14 2.57 38.64 44.19 2.77 0.46 314.78 2.03 27 0.86 2.00 35.44 40.64 2.60 0.44 314.76 1.98 28 0.57 1.43 32.03 36.87 2.42 0.42 314.74 1.94 29 0.29 0.86 28.45 32.89 2.22 0.39 314.71 1.88 30 0.00 0.29 24.71 28.74 2.01 0.37 314.69 1.82 25 12.00 10.00 ~ c 8.00 0 0 Q) Cl) a; ll.. a; Q) u.. 6.00 0 :0 :::s 0 -~ ~ 4.00 0 2 .00 0 .00 Inflow/Outflow Simulation 100-Year Storm Event 0 5 Pre-- Developme nt Hydrograph - I I - I I I I I • I ' I 10 ' ' ' ' ' ' 15 20 Time (Minutes) -Post-Post- Developme Developme nt Outflow nt Outflow Hydrograph With Without Detention Detention 26 25 30 .. -..... Post- Developme nt "Free- Flow· Inflow/Outflow Simulation 2-Year Storm Event 4.50 4.00 3.50 ~ 3.00 c 0 0 Cl> Cl) ... Cl> 2.50 Q. 'i Cl> L&- 0 :0 2 .00 ::::J 0 -~ 0 =§ 0 l.50 l.00 0 .50 0.00 0 5 10 15 20 25 30 Time (Minutes) ---Pre-Development Hydrograph ----Total Post -Development Hyd rograph 27 ~ c 0 5.00 4.50 4.00 3 .50 ~ 3.00 a; Q. a; C1> u.. 2.50 0 :0 :::> u -~ 2.00 0 ~ 0 1.50 l.00 0.50 0.00 0 Inflow/Outflow Simulation 5-Year Storm Event 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Total Post-Development Hydrogra p h 28 Inflow/Outflow Simulation 10-Yeor Storm Event 6.00 5.00 u 4 .00 c 0 0 G> Cl) Ci> Q.. ~ I.&-3 .00 0 :a :J u -~ 0 =§ 0 2 .00 l.00 0 .00 0 5 10 ---Pre-Development Hydrograph 15 20 25 30 Time (Minutes) ----Tota l Post-Development Hydrograph 29 ti) c: 0 0 ~ 7.00 6.00 5.00 a; 4.00 0... Q; Cl> u.. 0 :0 :::J ~ 3.00 ~ 0 =§ 0 2.00 1.00 0.00 0 Inflow/Outflow Simulation 25-Year Storm Event 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hy d rogr aph ----Total Post-Development Hyd ro graph 30 lnflow/Outtlow Simulation 50-Year Storm Event 8 .00 7.00 6 .00 -'tJ c 0 5 .00 0 G> ,,,, ... G> 0.. -G> G> 4 .00 u.. 0 :0 :J (.) -~ 0 3 .00 =§ 0 2 .00 l.00 0.00 0 5 10 15 20 25 30 Time (Minutes) ----Pre -Development Hydrograph ----Tot a l Post-Develo pment Hydrograph 31 Inflow/Outflow Simulation 100-Year Storm Event 8.00 7.00 6 .00 -"O c 0 5 .00 0 Cl> Cl) ... Cl> Cl.. -Cl> Cl> 4.00 L&. 0 :0 :::J 0 -~ 0 3 .00 !§ 0 2.00 1.00 0.00 0 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hydrograph ----Tota l Post-Development Hydrograph 32 Detention Pond Storage Volumes as Percent of Maximum Volume 100% 90% 80% 70% Cl> E :J 0 60% > E :J E ")( 50% 0 ::E 0 -40% c Cl> 0 ... Q) 0.. 30% 20% 10% 0% 2-year 5-year 10-year 25-year 50-year 100-year Design Storm 50-ear 100-ear Storm Depth 0 .52 0.54 Storm Elevation 314.84 314.86 Storm Volume 841 1055 1219 1443 1670 1756 Maximum Capacity 7143 7143 7143 7143 7143 7143 Percent of Capacity 12% 15% 17% 20% 23% 25% 33 rrU_ t/ IZ/'15 '\0 0 • .,, 0 C-0 YYI f¥" n °5f1 I'\ Por '1t?. Engineer's Estimate For Water Improvements I t\O c;fi~ Cc-p--n·- Se>'\ f;,,. if q . ~ College Station, Brazos County, Texas June, 1995 1. 46 L.F. $17.00 2. 33 L.F. $18 .00 Water Line 5-7 feet 3. 8" Diameter C900 -Class 200 P .~ C. 45 L.F . $19.00 Water Line 7-9 feet 4. 1 1/2 " Diameter Type "K" Copper L.F. Service Line 5. 16" Diameter Machine Boring w/16" $75.00 Diameter Steel Casing (3/8" M in. Wall Thickness 6. 8"X45 De ree M.J . Bend $250 .00 7. 8"X90 De ree M.J. Bend Ea . 8. 8"X8"X1 1/2" M.J . Tee 1 Ea . 9. 12" XS" M.J. Tapping Saddle w/8 " 1 Ea. Gate Valve and Box 10. Ea . $1,400 .00 11. Trench Safet L.S . $121 .77 ~~"''~ To1;.L~~!:..~f.~, For Water Improvements: $594.00 $855 .00 $1,428.00 $544 .00 $500.00 $250 .00 $250 .00 $2,500 .00 DEVELOPMENT PERMIT PERMIT NO. #289R FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Lot 2, Block 1, Brown Subdivision International Plumbing Supply SITE ADDRESS: Unkn.own OWNER: McHayden Dillard D illard Construction 13383 Highway 30 Co llege Station, Texas 77845 DRAINAGE BASIN: Lock Creek TYPE OF DEVELOPMENT: This permit is valid for the construction of the park;ng lot detention pond and all site grading for International Plumbing Supply Bui/d;ng. Eros;on control must be placed and maintained in accordance with the approved plans. Contractor shall prevent silt and debris from leaving the site in accordance with the City of Co llege Station Drainage Policy and Design Criteria. Owner and/or contractor shall be responsible for any damage to existing city streets or infrastructure due to h eavy machinery and/or equipment. This per1nit being tempormy, is valid only with in sixty (60) days of the date shown below, and is not intended to allow the complete development of the site as proposed. Any work performed after the expiration of this permit is not covered, and is conside red unauthorized. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage facilities . I hereby grant trus permit for development of an area inside/outside the special flood ~d area. All development shall be in accordance with the plans and specifications submitted d app roved by the City Engineer in the deve lopment permit application for the above named ct and all of the codes and ordinances of the City of College Station that apply. Dattl .Owner Date Contractor D ate \ DEVELOPMENT PE~T PERMIT NO. #289~ y FOR AREASOUTSIDE THE SPECIAL FLOOD HAZARD AREA RE : CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Lot 2, Block 1, Brown Subdivision Int ernationa l Plumbing Supply SITE ADDRESS: Unknown OWNER: McHayden Dillard Dillard Con struction 13383 Highway 30 College Station , Texas 77845 DRAINAGE BASIN: Lock Creek TYPE OF DEVELOP~NT: Thi s permit is valid for!s ite grading only. Erosion contro l must be placed and maintained in accordance with the approved plans. Contractor shall prevent si lt and debris from leaving the site in accordance with the City of College Station Drainage Policy and Design Criteria. Owner and/or con tra ctor shall be responsible for any damage to existing city streets or infrastructure due to heavy machinery and/or equipment. This permit being temporary, is valid only within sixty (6 0) days of the date shown below, and is not intended to allow the complete development of the site as proposed. Any work peiformed after the expiration of this permit is not covered, and is cons idered unauthorized. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage facilities. I hereby grant this permit for development of an area inside/outside the special flood hazard area. All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer in the development permit application for the ab named project and all of the codes and ordinances of the City of College Station that Date Date Date I~ Thi\\~~ -1/'.b/% Drainage Computations: Grading Plan of Lot 2 -Block 1 Brown Addition , 1.61 Acres Run-off coefficient= 0.40 Time of c oncentration= 10 minutes All "Q's " in cubic feet per second All Areas in acres ~~ Q -Pre-d evelopment to Grah am Road 0.81 2.0 5 2.49 2 .8 0 3.20 3.6 1 3.77 Q-Pre-development to rear 0.80 2.02 2.46 2 .76 3.16 3 .57 3.72 Q-Pre-development total 1.61 4.07 4.95 5.56 6.36 7.18 7.49 Peak Discharge Rates From Detention Pond: (should be smaller than Q-Pre-development) Q2 = 2.08 Q5 = 2.47 / Q10 = 2.73 Q25 = 3.07 Q50 = 3.43 Q100 = 3.57 Post-Development "Free Flow": (not to be exceeded by "free-flow" t o rear) Q2 = 2 .20 Q5 = 2 .68 I Q10 = 3 .00 Q25 = 3.43 Q50 = 3.88 Q100 = 4.05 t DRAINAGE COMPUTATIONS for Grading Plan of Lot 2 -Block 1 Brown Addition 1.61 Acre Tract ROBERT STEVENSON LEAGUE C ollege S ta ti on , Brazo s C o unty , T exas Pr epare d fo r Dillard Construction 13383 Highway 30 College Station, Texas 77845 Pr epare d bv: Garrett Engineering 4444 Carter Creek Parkway -Suite 108 Bryan , Texas 77802 Telephone : (409) 846-2688 Determine Total Pre-Development Peak Storm Water Discharge Rates Tributary Area ("A"): 1.61 Acres Pervious Area : 1.61 Acres Impervious Area : 0.00 Acres Run -Off Coefficient ("Cwt"): 0.40 Time Of Concentration ("T/c"): Woodlands: Low Elevation : High Elevation : Distance (Feet): Slope(% Grade): Ve loc ity ("Vw"): Time : Pastures: Low Elevation : High Elevation : Distance (Feet): Slope (% Grade): Velocity ("Vp "): Time : Pavements: Low Elevation : High Elevation : Distance (Feet): Slope (% Grade): Velocity ("Vpave"): Time : Total Travel Time: Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25 -Year: 9.86 50-Year: 11 .15 100-Year: 11 .64 Peak Discharge Rate ("O"): 2-Year: 4 .07 5-Year: 4.95 10-Year: 5.56 25-Year: 6.35 50 -Year: 7.18 100-Year: 7.50 c = 0.40 C= 0.98 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes 10 .00 Minutes Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Determine Post-development Peak Storm Water Dischar e No Detention Tributary Area ("A"): 1.61 Acres Pervious Area : 1.10 Acres Impervious Area : 0.51 Acres Run-Off Coefficient ("Cwt "): 0.58 Time Of Concentration ("T/c"): 10 Minutes (Min) Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11.15 100-Year: 11.64 c = 0.40 C= 0.98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Peak Discharge Rate ("O "): 2-Year: 5.95 Cubic Feet I Second 5-Year: 7.23 Cubic Feet I Second 10-Year: 8.11 Cubic Feet I Second 25-Year: 9.27 Cubic Feet I Second 50-Year : 10.48 Cubic Feet I Second 100-Year: 10 .94 Cubic Feet I Second Comparison Of Predevelopment And Post-development Peak Discharge Rates Predevelopment Post-Development Increase 2-Year: 4.07 Ft3/sec 5.95 Ft3/sec 1 .87 Ft3/sec 5-Year: 4.95 Ft3/sec 7 .2 3 Ft3/sec 2.28 Ft3/sec 10-Year: 5.56 Ft3 /sec 8.11 Ft3/sec 2.55 Ft3/sec 25-Year: 6.35 Ft3/sec 9.27 Ft3/sec 2.92 Ft3/sec 50-Year: 7 .18 Ft3 /sec 10.48 Ft3/sec 3.30 Ft3/sec 100-Year: 7.50 Ft3 /sec 10 .94 Ft3/sec 3.44 Ft3/sec Preliminary Determination Of Detention Pond Volume 2-Year: 1 .87 Ft3/sec x (30 Min . x 60 Sec. I 2 ) = 1,6 84 Cubic 5-Year: 2.28 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 2,048 Cubic 10-Year: 2 .55 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 2,299 Cubic 25-Year: 2.92 Ft3 /sec x (30 Min . x 60 Sec. I 2 ) = 2 ,625 Cubic 50-Year: 3.30 Ft3 /sec x (30 Min. x 60 Sec. I 2 ) = 2,968 Cubic 100-Year: 3.44 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 3,099 Cubic 2 Feet Feet Feet Feet Feet Feet Determine Post-Development "Free-Flqw 11 Peak Storm Water Discharge Tributary Area ("A"): 0.87 Acr es Pervious Area : 0 .87 Acres Impervious Area : 0.00 Acres Run-Off Coefficient ("Cwt"): 0.40 Time Of Concentration ("T/c"): 10 Minutes (Min) Hourly Intensity Rates ("I"): 2-Year : 6 .33 5-Year : 7 .69 10-Year: 8 .63 25-Year: 9.86 50-Year: 11 .15 100-Year: 11 .64 Peak Discharge Rate ("Q "): 2-Year: 2 .20 5-Year: 2.68 10-Year: 3 .00 25-Year: 3.43 50-Year: 3 .88 100-Year: 4 .05 3 c = 0.40 C= 0 .98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Determine Post-Development Flow Into Detention Pond Tributary Area ("A"): 0.74 Acres Pervious Area: 0.24 Acres Impervious Area : 0.50 Acres Run-Off Coefficient ("Cwt"): 0.66 Time Of Concentration ("T/c"): 1 O Minutes (Min) 0.00 Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25 -Year : 9.86 50-Year: 11 .15 100-Year: 11 .64 Peak Discharge Rate ("Q"): 2-Year: 3.10 5-Year: 3.77 10-Year: 4.23 25-Year: 4 .84 50-Year: 5.47 100-Year: 5.71 4 c = 0.40 C= 0.98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Pre-Development Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year {Minutes} Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.41 0.50 0.56 0.64 0.72 0.75 2 0.81 0.99 1.11 1.27 1.44 1.50 3 1.22 1.49 1.67 1.91 2.15 2.25 4 1.63 1.98 2.22 2.54 2.87 3.00 5 2.04 2.48 2.78 3.18 3.59 3.75 6 2.44 2.97 3.34 3.81 4.31 4.50 7 2.85 3.47 3.89 4.45 5.03 5.25 8 3.26 3.96 4.45 5.08 5.74 6.00 9 3.67 4.46 5.00 5.72 6.46 6.75 I -. . Peak=> 10 4.07 _4.95_ 5.5& 6.3§__ .J.18 7.50 -11 3.87 4.71 5.28 6.03 6.82 7.12 12 3.67 4.46 5.00 5.72 6.46 6.75 13 3.46 4.21 4.73 5.40 6.10 6.37 14 3.26 3.96 4.45 5.08 5.74 6.00 15 3.06 3.72 4.17 4.76 5.38 5.62 16 2.85 3.47 3.89 4.45 5.03 5.25 17 2.65 3.22 3.61 4.13 4.67 4.87 18 2.44 2.97 3.34 3.81 4.31 4.50 19 2.24 2.72 3.06 3.49 3.95 4.12 20 2.04 2.48 2.78 3.18 3.59 3.75 21 1.83 2.23 2.50 2.86 3.23 3.37 22 1.63 1.98 2.22 2.54 2.87 3.00 23 1.43 1.73 1.95 2.22 2.51 2.62 24 1.22 1.49 1.67 1.91 2.15 2.25 25 1.02 1.24 1.39 1.59 1.79 1.87 26 0.81 0.99 1.11 1.27 1.44 1.50 27 0.61 0.74 0.83 0.95 1.08 1.12 28 0.41 0.50 0.56 0.64 0.72 0.75 29 0.20 0.25 0.28 0.32 0.36 0.37 30 0.00 0.00 0.00 0.00 0.00 0.00 5 Post-Development Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.59 0.72 0.81 0.93 1.05 1.09 2 U9 1.45 1.62 1.85 2.10 2.19 3 1.78 2.17 2.43 2.78 3.14 3.28 4 2.38 2.89 3.25 3.71 4.19 4.38 5 2.97 3.61 4.06 4.63 5.24 5.47 6 3.57 4.34 4.87 5.56 6.29 6.56 7 4.16 5.06 5.68 6.49 7.33 7.66 8 4.76 5.78 6.49 7.41 8.38 8.75 9 5.35 6.51 7.30 8.34 9.43 9.84 c=Io---g_g~ "~).23 --n - -Peak=> 8.11 9.27 10.48 10.94 --------~ 11 5.65 6.87 7.71 8.80 9.95 10.39 12 5.35 6.51 7.30 8.34 9.43 9.84 13 5.05 6.15 6.90 7.88 8.91 9.30 14 4.76 5.78 6.49 7.41 8.38 8.75 15 4.46 5.42 6.09 6.95 7.86 8.20 16 4.16 5.06 5.68 6.49 7.33 7.66 17 3.86 4.70 5.27 6.02 6.81 7.11 rn 3.57 4.34 4.87 5.56 6.29 6.56 19 3.27 3.98 4.46 5.10 5.76 6.02 20 2.97 3.61 4.06 4.63 5.24 5.47 21 2.68 3.25 3.65 4.17 4.71 4.92 22 2.38 2.89 3.25 3.71 4.19 4.38 23 2.08 2.53 2.84 3.24 3.67 3.83 24 1.78 2.17 2.43 2.78 3.14 3.28 25 1.49 1.81 2.03 2.32 2.62 2.73 26 1.19 1.45 1.62 1.85 2.10 2.19 27 0.89 1.08 1.22 1.39 1.57 1.64 28 0.59 0.72 0.81 0.93 1.05 1.09 29 0.30 0.36 0.41 0.46 0.52 0.55 30 0.00 0.00 0.00 0.00 0.00 0.00 6 Post-Development "Free-Flow" Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.22 0.27 0.30 0.34 0.39 0.41 2 0.44 0.54 0.60 0.69 0.78 0.81 3 0.66 0.80 0.90 1.03 1.16 1.22 4 0.88 1.07 1.20 1.37 1.55 1.62 5 1.10 1.34 1.50 1.72 1.94 2.03 6 1.32 1.61 1.80 2.06 2.33 2.43 7 1.54 1.87 2.10 2.40 2.72 2.84 8 1.76 2.14 2.40 2.75 3.10 3.24 9 1.98 2.41 2.70 3.09 3.49 3.65 -3.60 3.43 "3.88 Peak=> I 10 2.20 2.68 4.05 --·-----.. -11 2.09 2.54 2.85 3.26 3.69 3.85 12 1.98 2.41 2.70 3.09 3.49 3.65 13 1.87 2.28 2.55 2.92 3.30 3.44 14 1.76 2.14 2.40 2.75 3.10 3.24 15 1.65 2.01 2.25 2.57 2.91 3.04 16 1.54 1.87 2.10 2.40 2.72 2.84 17 1.43 1.74 1.95 2.23 2.52 2.63 18 1.32 1.61 1.80 2.06 2.33 2.43 19 1.21 1.47 1.65 1.89 2.13 2.23 20 1.10 1.34 1.50 1.72 1.94 2.03 21 0.99 1.20 1.35 1.54 1.75 1.82 22 0.88 1.07 1.20 1.37 1.55 1.62 23 0.77 0.94 1.05 1.20 1.36 1.42 24 0.66 0.80 0.90 1.03 1.16 1.22 25 0.55 0.67 0.75 0.86 0.97 1.01 26 0.44 0.54 0.60 0.69 0.78 0.81 27 0.33 0.40 0.45 0.51 0.58 0.61 28 0.22 0.27 0.30 0.34 0.39 0.41 29 0.11 0.13 0.15 0.17 0.19 0.20 30 0.00 0.00 0.00 0.00 0.00 0.00 7 Post-Development Flow Routed Through Detention Pond Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.31 0.38 0.42 0.48 0.55 0.57 2 0.62 0.75 0.85 0.97 1.09 1.14 3 0.93 1.13 1.27 1.45 1.64 1.71 4 1.24 1.51 1.69 1.93 2.19 2.28 5 1.55 1.89 2.12 2.42 2.73 2.85 6 1.86 2.26 2.54 2.90 3.28 3.42 7 2.17 2.64 2.96 3.39 3.83 4.00 8 2.48 3.02 3.39 3.87 4.37 4.57 9 2.79 3.40 3.81 4.35 4.92 5.14 I -3.77 -. - - -Peak=> 10 ' 3.10 4.~ -4.84 __ 5.47 5.71 11 2.95 3.58 4.02 4.59 5.19 5.42 12 2.79 3.40 3.81 4.35 4.92 5.14 13 2.64 3.21 3.60 4.11 4.65 4.85 14 2.48 3.02 3.39 3.87 4.37 4.57 15 2.33 2.83 3.18 3.63 4.10 4.28 16 2.17 2.64 2.96 3.39 3.83 4.00 17 2.02 2.45 2.75 3.14 3.55 3.71 18 1.86 2.26 2.54 2.90 3.28 3.42 19 1.71 2.07 2.33 2.66 3.01 3.14 20 1.55 1.89 2.12 2.42 2.73 2.85 21 1.40 1.70 1.91 2.18 2.46 2.57 22 1.24 1.51 1.69 1.93 2.19 2.28 23 1.09 1.32 1.48 1.69 1.91 2.00 24 0.93 1.13 1.27 1.45 1.64 1.71 25 0.78 0.94 1.06 1.21 1.37 1.43 26 0.62 0.75 0.85 0.97 1.09 1.14 27 0.47 0.57 0.64 0.73 0.82 0.86 28 0.31 0.38 0.42 0.48 0.55 0.57 29 0.16 0.19 0.21 0.24 0.27 0.29 30 0.00 0.00 0.00 0.00 0.00 0.00 8 6.00 ... Cl> 5.00 0... -Cl> Cl> 4.00 LL. 0,.... ·-"O ..c c ::;:, 0 3.00 u 0 -Cl> Cl> (f) 0) 2.00 ... 0 .r; 0 VI 1.00 0 0.00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 2-Year Storm Event 5 10 15 20 25 Time (Minutes) ----Pre-Development Hydrograph ----To t a l Post-Deve lopment Hydrograph Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 5-Year Storm Event 30 ~ 7.00 +-----+---~~---+-----+----1------- 0... ~ 6 .00+-----+---l--f--------3'oc---t-----+----f----- LL. .2 15' 5 .00 +-----+--f----,k:::-----t-"'7----+----f-------1 ..c c 8 8 4.00+-----+,_-+--~-~,,__--t-----3',,.--l-----~-----< -Cl> ~ (f) 3 .00 +---~'-t--F--------l-----+-----::>o....,--------+---""-------1------1 5 -n 2 .00 VI 0 1.00 +-_,_,<----+-----+------+----jf-----+=-~-_-.j 0 5 10 15 20 25 Time (Minutes) Pre-D evelopment Hydrograph ----Post-Development Outflow Hydrograph Without Detention 9 30 ... C1> Q. -C1> C1> LL. 0 "'"' 9 .00 8 .00 7.00 6 .00 Total Pre -Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 10 -Year Storm Eve nt ·-'O .g c 5 .00 u 0 ~o C1> ~ ()) ... 0 .t:. 0 .,, i5 ... C1> Q. -C1> C1> LL. 0"'"' ·-'O .0 c J 0 u 0 ~ C1> C1> Cl) ()) ... 0 .t:. 0 .,, i5 4.00 3 .00 2 .00 l.00 0 .00 0 5 10 Pre-Development Hydrograph 15 20 25 30 Ti me (M in utes) Post-Dev elopment Outflow Hydrograph With out Detenti o n Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 25-Year Storm Eve nt 10 .00 9 .00 8 .00 7.00 6 .00 5 .00 4 .00 3.00 2.00 l.00 0.00 0 5 10 Pre-Development Hydrograph 15 20 25 30 Time (Minutes) 10 Post -Development Outflow Hyd rograph With out Detent ion ... Cl> 0... -Cl> Cl> u. o-·-'U .D c: :J 0 u 0 -Cl> Cl> (/) O'> ... 0 ..c: 0 V> a ... Cl> 0... -Cl> Cl> u. o -·-'U .D c: :J 0 (.) 0 -Cl> Cl> (/) O'> ... 0 ..c: 0 V> a 12.00 10 .00 8.00 6 .00 4 .00 2.00 0.00 0 Total Pre-Developm e nt Vs . Tota l Post-Development (No Detention) Peak Discharge Rates 50-Year Storm Ev ent 5 10 15 20 25 Time (M inutes) 30 Pre -Development Hydr ograph ----Post-Develo pment Outflow Hydrograph Wit hout Detention 12.00 10 .00 8 .00 6 .00 4.00 2 .00 0 .00 0 Total Pre-Development Vs . Total Post -Development (No Detention) Peak Discharge Rates 100 -Year Storm Ev ent 5 10 15 2o 25 Ti me (M inutes) Pre-Development Hydrograph ----Post -Development Outflow Hydrograph Without Detentio n 1 1 30 Detention Pond De th Vs. Volume ,.... Qi Cl> u.. 1.20 l.00 0.80 ;; 0.60 a. Cl> 0 0.40 0.20 0 .00 Elevation Depth Volume (Feet) (Ft3) 314.32 0 .00 0 314.62 0.30 479 314.75 0.43 1 ,067 315 .00 0 .68 2 ,586 315 .25 0 .93 4,581 315 .50 1.18 7 ,055 Detention Pond Depth Vs. Volume 0 l ,000 2 ,000 3 ,000 4 ,000 5 ,000 6 ,000 7 ,00.0 8 ,000 Detention Pond Volume (Cubic Feet) 12 Rating Curve For Outlet Control Structure Weir Length(L): 3 .00 De th Vs. Volume Elevation Depth Discharge (Feet) Ft3/Sec 314 .32 0 .00 0 .00 314 .62 0.30 1.48 314 .75 0.43 2.54 315 .00 0.68 5.05 315.25 0.93 8.07 315 .50 1.18 11.54 Rating Curve For Outlet Control Structure Depth Vs. 1.20 1.00 0.80 i Q) LL. ;; 0 .60 a. Q) 0 0.40 0 .20 0.00 0.00 2 .00 Volume 4.00 6 .00 8 .00 10 .00 Discharge (Cubic Feet Per Second) 13 12 .00 I Storage Indication Curve Depth Storage Discharge 2s/t 2s/t+O (Feet) (Ft3) (Ft3/Sec) (Ft3/Sec) (Ft3/Sec) 0.00 0 0 .00 0 .00 0 .00 0 .30 479 1.48 15.97 17.45 0.43 1,067 2 .54 35 .57 38 .10 0 .6 8 2,586 5.05 86 .20 91 .25 0 .93 4,581 8.07 152.70 160.77 1.18 7,055 11 .54 235 .17 246.70 Storage Indication Curve ........ 1J c 0 8 .00 0 Cl> (/) ... Cl> 0.. -Cl> Cl> LL. 6.00 0 :0 :I u "" Cl> O'> ... 0 .t::. 4.00 0 U) a 0.00 50 .00 100 .00 150 .00 200.00 250.00 2s/t+O (Cubic Feet Per Second) 14 Inflow I Outflow Simulation 2-Year Storm Event Time Inflow 11+ 12 2s/t-O 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.31 0.31 0.26 0.31 0.03 0.02 314.34 0.43 2 0.62 0.93 0.99 1.19 0.10 0.05 314.37 0.67 3 0.93 1.55 2.11 2.54 0.22 0.08 314.40 0.86 4 1.24 2.17 3.55 4.28 0.36 0.12 314.44 1.03 5 1.55 2.79 5.27 6.35 0.54 0.15 314.47 1.17 6 1.86 3.41 7.21 8.68 0.74 0.19 314.51 1.30 7 2.17 4.03 9.34 11.24 0.95 0.22 314.54 1.42 8 2.48 4.65 11.62 13.99 1.19 0.26 314.58 1.53 9 2.79 5.27 14.03 16.89 1.43 0.29 314.61 1.63 10 3.10 5.89 16.71 19.92 1.61 0.32 314.64 1.69 11 2.95 6.05 19.26 22.76 1.75 0.34 314.66 1.74 12 2.79 5.74 21.27 25.00 1.87 0.35 314.67 1.78 13 2.64 5.43 22.79 26.70 1.95 0.36 314.68 1.80 14 2.48 5.12 23.88 27.91 2.02 0.37 314.69 1.82 15 2.33 4.81 24.58 28.69 2.06 0.37 314.69 1.83 16 2.17 4.50 24.93 29.08 2.08 0.38 314.70 1.84 17 2.02 4.19 24.96 29.12 2.08 0.38 314.70 1.84 18 1.86 3.88 24.71 28.84 2.06 0.37 314.69 1.84 19 1.71 3.57 24.21 28.28 2.03 0.37 314.69 1.83 20 1.55 3.26 23.49 27.47 1.99 0.37 314.69 1.81 21 1.40 2.95 22.55 26.43 1.94 0.36 314.68 1.80 22 1.24 2.64 21.44 25.19 1.88 0.35 314.67 1.78 23 1.09 2.33 20.16 23.77 1.80 0.34 314.66 1.76 24 0.93 2.02 18.73 22.18 1.72 0.33 314.65 1.73 25 0.78 1.71 17.18 20.44 1.63 0.32 314.64 1.70 26 0.62 1.40 15.50 18.57 1.54 0.31 314.63 1.66 27 0.47 1.09 13.77 16.58 1.41 0.29 314.61 1.62 28 0.31 0.78 12.08 14.55 1.23 0.27 314.59 1.55 29 0.16 0.47 10.42 12.55 1.06 0.24 314.56 1.47 30 0.00 0.16 8.78 10.58 0.90 0.21 314.53 1.39 15 6 .00 5.00 ...... "O g 4.00 0 Q) (/) a; CL. Qi Q) ~ 3.00 0 :.0 ::::J u ....... ?; 0 E ::::J 2 .00 0 1.00 0 .00 0 Inflow/Outflow Simulation 2-Year Storm Event • I I • I I I I 5 Pre----- De ve lopme nt Hydrograph ' I I ' ' ' 10 ' ' ' ' 15 ' ' Time (Minutes) Post- Developme nt O utfl ow Hyd rograph Without Detention 16 20 25 30 Post--• -• -• Post- Developme De velo pme nt Outflow nt "F ree- With Flow · Detention Inflow I Outflow Simulation 5-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 314 .32 0 .00 1 0.38 0 .38 0 .31 0.38 0 .03 0 .02 314 .34 0.46 2 0.75 1.13 1.20 1.45 0 .12 0 .06 314.38 0.72 3 1 .13 1.89 2 .56 3.09 0.26 0 .09 314.41 0 .92 4 1.51 2 .64 4.32 5 .20 0.44 0 .13 314.45 1.10 5 1.89 3.40 6.41 7 .72 0 .65 0 .17 314.49 1.25 6 2 .26 4 .15 8 .77 10.56 0 .90 0 .21 314.53 1.39 7 2 .64 4 .90 11 .35 13.67 1.16 0 .26 314 .58 1.51 8 3 .02 5.66 14.13 17.01 1.44 0.30 314 .62 1.63 9 3.40 6.41 17.27 20.54 1.64 0.32 314.64 1.70 10 3.77 7 .17 20 .76 24.43 1.84 0 .35 314.67 1.77 11 3 .58 7.36 24 .07 28 .12 2 .03 0.37 314.69 1.82 12 3.40 6 .98 26 .69 31 .04 2 .18 0 .39 314 .71 1.87 13 3 .21 6 .6 0 28 .71 33 .29 2 .29 0.40 314.72 1.90 14 3 .02 6 .22 30 .19 34 .94 2 .38 0.41 314 .73 1.92 15 2 .83 5 .85 31 .17 36 .03 2.43 0.42 314 .74 1.94 16 2 .64 5.47 31 .72 36 .64 2.46 0.42 314.74 1.95 17 2.45 5.09 31 .87 36 .81 2.47 0.42 314 .74 1.95 18 2 .26 4.72 31 .66 36 .58 2.46 0.42 314 .74 1.95 19 2 .07 4 .34 31.14 36.00 2.43 0.42 314.74 1.94 20 1.89 3 .96 30 .33 35 .10 2.38 0.41 314.73 1.93 21 1.70 3 .58 29.27 33 .92 2 .32 0.41 314.73 1.91 22 1.51 3 .21 27 .98 32.48 2 .25 0.40 314 .72 1.89 23 1.32 2 .83 26.48 30 .81 2 .16 0.39 314.71 1.87 24 1.13 2.45 24 .80 28 .93 2.07 0.38 314 .70 1.84 25 0 .94 2 .07 22 .95 26.87 1.96 0 .36 314 .68 1.81 26 0.75 1.70 20 .95 24 .65 1.85 0 .35 314.67 1.77 27 0.57 1.32 18.82 22.27 1.73 0.33 314 .65 1.73 28 0 .38 0.94 16.57 19.76 1.60 0 .32 314.64 1.69 29 0 .19 0.57 14.2 3 17.13 1.45 0 .30 314 .62 1.63 30 0.00 0 .19 11 .97 14.42 1.22 0.26 314.58 1.54 17 :S-c 0 8 .00 7.00 6.00 g 5 .00 <h .... Q) a.. Qj Q) ~ 4 .00 0 :a j u ........ ~ 3.00 ~ j 0 2 .00 1.00 0 .00 0 Inflow/Outflow Simulation 5-Year Storm Event 5 Pre -- Developme nt Hydrograph - I I - I I - I I I " I " I ' " " " " 10 15 20 25 nme (Minutes) Post-Post-··-··-·· De v elopme Devel opme nt O utfl ow nt Outflow Hyd rogra ph With Without De t ention Detenti o n 18 30 Post- De velo pme nt "Free- Flow" Inflow I Outflow Simulation 10-Year Storm Event Time Inflow 11+ 12 2s/t -0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 314 .32 0 .00 1 0.42 0.42 0 .35 0.42 0.04 0 .03 314 .35 0.48 2 0 .85 1.27 1 .35 1.62 0.14 0 .06 314 .38 0.74 3 1 .27 2 .12 2 .88 3.46 0 .29 0.10 314.42 0 .96 4 1.69 2 .96 4.85 5.84 0 .50 0.14 314.46 1.14 5 2 .12 3 .81 7.19 8.66 0 .73 0 .19 314.51 1.30 6 2.54 4.66 9 .84 11 .85 1.00 0.23 314 .55 1.44 7 2.96 5 .50 12 .74 15 .35 1.30 0 .28 314 .60 1.57 8 3 .39 6 .35 15 .97 19 .10 1.56 0.31 314.63 1.67 9 3 .81 7 .20 19 .62 23 .17 1.77 0 .34 314 .66 1.75 10 4 .23 8 .05 23.66 27 .67 2 .00 0 .37 314.69 1.82 11 4 .02 8 .26 27.48 3 1.92 2 .22 0.39 314.71 1.88 12 3 .81 7.83 30 .52 35.31 2 .39 0.41 314.73 1.93 13 3 .60 7.41 32 .88 37.93 2 .53 0.43 314.75 1.96 14 3 .39 6 .99 34 .62 39 .86 2 .62 0.44 314 .76 1.99 15 3 .18 6 .56 35 .82 41 .18 2 .68 0.45 314.77 2 .00 16 2 .96 6 .14 36 .52 41 .96 2 .72 0.45 314.77 2 .01 17 2 .75 5.72 36 .77 42 .23 2 .73 0.45 314 .77 2.02 18 2 .54 5 .29 36 .61 42 .06 2 .72 0.45 314 .77 2 .01 19 2 .33 4.87 36 .09 41.48 2.70 0.45 314 .77 2.01 20 2.12 4.45 35 .23 40 .53 2 .65 0.44 314 .76 2 .00 21 1.91 4 .02 34 .07 39.25 2.59 0.44 314 .76 1.98 22 1 .69 3.60 32 .64 37 .67 2 .52 0.43 314.75 1.96 23 1.48 3 .18 30.97 35 .81 2.42 0.42 314.74 1 .94 24 1.27 2 .75 29 .10 33 .72 2 .31 0.40 314 .72 1.91 25 1.06 2 .33 27.04 31.43 2.20 0 .39 314 .71 1.87 26 0 .85 1 .91 24 .81 28 .94 2.07 0 .38 314 .70 1.84 27 0.64 1.48 22.42 26.29 1.93 0 .36 314.68 1.80 28 0.42 1.06 19 .91 23.48 1.79 0.34 314.66 1.75 29 0 .21 0 .64 17.27 20 .54 1.64 0 .32 314 .64 1.70 30 0 .00 0.21 14 .52 17.48 1.48 0 .30 314 .62 1.64 19 9 .00 8 .00 7.00 B g 6.00 0 Cl) (I) .... Cl) Q.. 5 .00 -Cl) Cl) u.. 0 :0 :::J 4.00 () -?; 0 ~ 3.00 0 2.00 l.00 0.00 Inflow/Outflow Simulation 10-Year Storm Event 0 5 Pre --- Developme nt Hydrograph I I - I I I I - I ' I ' I ' ' 10 ' ' ' ' ' ' 15 Time (Minutes) Post- Developme nt Outflow Hyd rograph Without Detenti o n 20 20 25 Pos t --------- Developme nt Outflow With Detention 30 Post- Developme nt "Free- Flow· Inflow I Outflow Simulation 25-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 0.48 0.48 0.40 0.48 0.04 0.03 314.35 0.50 2 0.97 1.45 1.54 1.85 0.16 0.07 314.39 0.78 3 1.45 2.42 3.29 3.96 0.34 0.11 314.43 1.00 4 1.93 3.39 5.54 6.67 0.57 0.16 314.48 1.19 5 2.42 4.35 8.22 9.89 0.84 0.21 314.53 1.36 6 2.90 5.32 11.24 13.53 1.15 0.25 314.57 1.51 7 3.39 6.29 14.56 17.53 1.48 0.30 314.62 1.64 8 3.87 7.25 18.41 21.82 1.70 0.33 314.65 1.72 9 4.35 8.22 22.73 26.63 1.95 0.36 314.68 1.80 10 4.84 9.19 27.48 31.92 2.22 0.39 314.71 1.88 11 4.59 9.43 31.96 36.91 2.48 0.42 314.74 1.95 12 4.35 8.95 35.56 40.90 2.67 0.44 314.76 2.00 13 4.11 8.46 38.39 44.03 2.82 0.46 314.78 2.04 14 3.87 7.98 40.52 46.37 2.93 0.47 314.79 2.06 15 3.63 7.50 42.00 48.01 3.01 0.48 314.80 2.08 16 3.39 7.01 42.91 49.01 3.05 0.49 314.81 2.09 17 3.14 6.53 43.29 49.44 3.07 0.49 314.81 2.10 18 2.90 6.05 43.20 49.34 3.07 0.49 314.81 2.10 19 2.66 5.56 42.68 48.76 3.04 0.49 314.81 2.09 20 2.42 5.08 41.77 47.76 2.99 0.48 314.80 2.08 21 2.18 4.59 40.51 46.36 2.93 0.47 314.79 2.06 22 1.93 4.11 38.93 44.62 2.85 0.46 314.78 2.04 23 1.69 3.63 37.06 42.56 2.75 0.45 314.77 2.02 24 1.45 3.14 34.93 40.20 2.64 0.44 314.76 1.99 25 1.21 2.66 32.57 37.59 2.51 0.43 314.75 1.96 26 0.97 2.18 30.01 34.74 2.37 0.41 314.73 1.92 27 0.73 1.69 27.29 31.71 2.21 0.39 314.71 1.88 28 0.48 1.21 24.40 28.49 2.05 0.37 314.69 1.83 29 0.24 0.73 21.38 25.13 1.87 0.35 314.67 1.78 30 0.00 0.24 18.24 21.63 1.69 0.33 314.65 1.72 21 10.00 9 .00 8.00 7 .00 6.00 5.00 4.00 3.00 2.00 1.00 0 .00 Inflow/Outflow Simulation 25-Year Storm Event 0 5 Pre --- De velopme nt Hydrograph I I - I I - I I I ' I • I 10 ' ' 15 20 Time (Minutes) Post-Post - Developme Deve lopme nt Outflow nt Outflow Hydrograph With Without De tention Detention 22 25 -------- 30 Post- Developme nt 'Free- Flow' Inflow I Outflow Simulation 50-Yea r Storm Event T ime Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0 .00 0 .00 0 .00 0 .00 0.00 0 .00 314 .32 0 .00 1 0 .55 0 .55 0.45 0 .55 0 .05 0 .03 314.35 0.52 2 1.09 1.64 1.74 2.09 0.18 0 .07 314 .39 0 .81 3 1.64 2 .73 3 .71 4.47 0.38 0 .12 314.44 1.04 4 2 .19 3 .83 6 .26 7.54 0.64 0 .17 314.49 1.24 5 2 .73 4 .92 9 .29 11 .18 0.95 0.22 314 .54 1.42 6 3 .28 6.01 12 .71 15.30 1.30 0.27 314 .59 1.57 7 3 .83 7 .11 16.61 19 .81 1.60 0.32 314 .64 1.69 8 4 .37 8 .20 21 .10 24 .81 1.86 0 .35 314.67 1.77 9 4 .92 9.29 26 .11 30 .39 2.14 0.38 314.70 1.86 10 5.47 10.39 31.58 36.50 2.46 0.42 314 .74 1.95 11 5 .19 10.66 36 .78 42 .25 2 .73 0.45 314.77 2 .02 12 4.92 10.11 40 .99 46.89 2 .95 0.48 314.80 2 .07 13 4 .65 9.57 44 .30 50 .55 3 .13 0.49 314.81 2.11 14 4 .37 9.02 46 .81 53 .32 3.26 0.51 314 .83 2 .14 15 4 .10 8.47 48 .59 55 .28 3 .35 0 .52 314.84 2 .16 16 3.83 7 .93 49 .70 56 .51 3.41 0.52 314.84 2.17 17 3.55 7 .38 50 .21 57 .08 3.43 0.53 314 .85 2.18 18 3 .28 6.83 50 .18 57 .05 3.43 0 .53 314 .85 2 .18 19 3 .01 6.29 49.66 56.47 3.4 0 0.52 314.84 2 .17 20 2 .73 5.74 48 .69 55.40 3.35 0 .52 314 .84 2 .16 21 2.46 5 .19 47 .32 53 .88 3 .28 0 .51 314.83 2 .14 22 2 .19 4.65 45.58 51.97 3 .19 0 .50 314 .82 2 .12 23 1.91 4 .10 43 .51 49 .68 3 .08 0.49 314 .81 2 .10 24 1.64 3 .55 41 .14 47 .07 2 .96 0.48 314.80 2 .07 25 1.37 3.01 38 .51 44 .15 2 .82 0.46 314 .78 2 .04 26 1.09 2.46 35 .62 40 .97 2.67 0.45 314 .77 2 .00 27 0 .82 1.91 32 .52 37 .53 2 .51 0.43 314 .75 1.96 28 0.55 1.37 29 .24 33 .88 2.32 0.41 314 .73 1.91 29 0 .27 0 .82 25 .81 30 .06 2 .13 0 .38 314.70 1.85 30 0 .00 0 .27 22 .24 26 .08 1.92 0 .36 314 .68 1.79 23 12 .00 10.00 :0 g 8.00 0 Q) Cl) Qi Q. Q) Q) u.. 6.00 0 :0 :J u -3'; 0 ~ 4.00 0 2.00 0.00 Inflow/Outflow Simulation 50-Year Storm Event I ' ' I '\. I ' I ' ' I ' • ' I I I ' ' 0 5 10 15 20 25 30 Time (Minutes) Pre-----Post-Post-.. --... -Post- Developme Developme Developme Developme nt nt Outflow nt Outflow nt 'Free- Hydrograph Hydrograph With Flow' Without Detention Detention 24 Inflow I Outflow Simulation ; 00-Ye a r Storm Event Time Inflow Ii+ 12 2s /t -O 2s/t+O Outflow Depth Elevation Ve locity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0 .00 0 .00 0 .00 0 .00 0 .00 0.00 3i4.32 0 .00 ; 0 .57 0.57 0.47 0 .57 0 .05 0 .03 3i4.35 0 .53 2 ; . ;4 ; .7i ; .82 2 .i9 O.i9 0 .08 3i4.40 0 .82 3 ; .7i 2 .85 3.88 4 .67 0.40 O.i2 3i4.44 i .06 4 2 .28 4 .00 6 .54 7.87 0 .67 O.i8 3i4.50 i .26 5 2 .85 5 .i4 9.70 ; ; .68 0 .99 0 .23 3i4.55 ; .44 6 3.42 6 .28 i3 .27 i5 .97 i .35 0 .28 3i4.60 i.60 7 4 .00 7.42 i7.40 20.69 ; .64 0 .32 3i4.64 i.70 8 4 .57 8 .56 22 .i3 25.96 ; .92 0 .36 3i4.68 i.79 9 5 .i4 9 .70 27.40 3; .83 2 .22 0 .39 3; 4 .7i i .88 ;o 5 .7i i0 .84 33.i6 38 .24 2 .54 0.43 3; 4 .75 i .97 ; ; 5.42 ; ; . ; 3 38 .63 44 .29 2 .83 0.46 3i4 .78 2 .04 i2 5 .i4 i0 .56 43 .06 49 .i9 3 .06 0.49 3i4.8i 2 .09 ;3 4 .85 9 .99 46 .57 53 .05 3 .24 0 .5i 3i4.83 2.i3 i4 4 .57 9.42 49 .22 55 .98 3 .38 0 .52 3i4.84 2.i6 ;5 4 .28 8 .85 5;.;; 58.07 3.48 0 .53 3i4.85 2.i9 i6 4 .00 8 .28 52 .30 59.38 3 .54 0.54 3i4.86 2 .20 ;7 3 .7i 7 .7i 52.86 60.00 3 .57 0.54 3i4.86 2.20 i8 3.42 7 .i3 52.85 60 .00 3 .57 0 .54 3i4.86 2 .20 ;9 3 .i4 6 .56 52 .33 59.42 3 .54 0 .54 3i4.86 2 .20 20 2.85 5.99 5; .34 58 .32 3.49 0.53 3i4.85 2.i9 2i 2 .57 5.42 49 .92 56 .76 3.42 0 .52 314 .84 2 .i7 22 2 .28 4.85 48 .13 54 .78 3 .32 0 .5i 3i4 .83 2 .i5 23 2 .00 4 .28 45 .98 52.4i 3.2i 0 .50 3i4.82 2 .i3 24 ; .7i 3 .7i 43.52 49.69 3 .08 0.49 3i4.8i 2 .iO 25 1 .43 3 .i4 40 .78 46 .66 2 .94 0.47 314 .79 2 .07 26 1 .14 2 .57 37.78 43 .35 2.79 0.46 3i4.78 2 .03 27 0 .86 2 .00 34.54 39.77 2 .62 0.44 314 .76 1 .99 28 0 .57 ; .43 3;. 11 35 .97 2.43 0.42 314 .74 1 .94 29 0.29 0 .86 27.52 3; .97 2 .22 0.39 3i4.7i 1 .88 30 0 .00 0 .29 23 .79 27 .8i 2 .01 0 .37 3i4.69 ; .82 25 Inflow/Outflow Simulation 100-Year Storm Event 12.00 I ' I 10 .00 ' ' " I ' • " I ' ........ "O 8 .00 I c 0 I 0 ' Cl> I (/) ... Cl> 0.. -Cl> Cl> 6 .00 u.. 0 :.0 ::::J () ......, ~ 0 E 4 .00 ::::J 0 2 .00 0.00 0 5 10 15 20 25 30 Time (Minutes) Pre-. . . -Post-Po st--------· Post- De ve lo pme Developme Developm e De velopme nt nt Outflow nt Outflow nt "Free- Hydrograph Hydrograph With Fl ow· Without Detention Detention 26 Inflow/Outflow Simulation 2-Year Storm Event 4 .50 4 .00 3 .50 B 3.00 c 0 0 Q) (/) ... Q) 2 .50 Q.. -Q) Q) LL. 0 :0 2.00 ::::J (.) -~ 0 E ::::J 0 l.50 l.00 0.50 0 .00 0 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Total Post-De velopment Hydrograph 27 Inflow/Outflow Simulation 5-Year Storm Event 5 .00 4 .50 4.00 3.50 ""' "O c: 0 0 QI 3.00 (/) ... QI c.. -QI QI 2 .50 ~ 0 :a :::> u -~ 2 .00 0 E :::> 0 1.50 1.00 0 .50 0 .00 0 5 10 15 20 25 30 Time (Minutes) Pre-Deve lopment Hydrograph ----To t a l Post-De velo pm ent Hydrograph 28 6.00 5.00 1j' 4 .00 c: 0 0 Cl> Cl) a; Q,,, Qi Cl> ...... 3.00 0 :0 ::::J () -~ 0 =§ 0 2.00 1.00 0 .00 0 Inflow/Outflow Simulation 10-Year Storm Event 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydr ograph ----Tota l Po st-Develo pment Hydrograph 29 -'O c 0 0 Q) (/) ... Q) 0.. -Q) Q) LL. 0 :0 :J 7.00 6 .00 5.00 4 .00 ~ 3 .00 ~ 0 E :J 0 2 .00 1.00 0.00 0 Inflow/Outflow Simulation 25-Year Storm Event 5 lO 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Tota l Post-Development Hydrograph 30 Inflow/Outflow Simulation 50-Year Storm Event 8.00 7.00 6.00 ....... "O c 0 5 .00 0 Cl> Cl) ... Cl> a.. -Cl> Cl> 4.00 u.. 0 :a ::::J u ........ ~ 0 3 .00 E ::::J 0 2 .00 1.00 0 .00 0 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Total Post-Development Hydrograph 31 Inflow/Outflow Simulation 100-Year Storm Event 8 .00 7.00 6 .00 ........ "O c 0 5 .00 0 Q) Cl) ..... Q) Q,,, -Q) Q) 4 .00 LI- 0 :0 :J u ....... ~ 0 3.00 == :J 0 2 .00 1.00 0.00 0 5 10 15 20 25 30 nme (Minutes) ---Pre-Development Hydrograph ----To t a l Post-Develop m ent Hydrograph 32 Detention Pond Storage Volumes as Percent of Maximum Volume 100% 90% 80% 70% G> E :J 0 60% > E :J E ')( 50% 0 ~ -0 -40% c: G> 0 .... G> a.. 30% 20% 10% 0% 2-year 5-year 10-year 25-year 50-year 100-year Design Storm 50-ear 100-ear Storm Depth 0 .53 0 .54 Storm Elevation 314.70 314 .74 314 .77 314 .81 314 .85 314.86 Storm Volume 824 1033 1199 1422 1650 1736 Maximum Capacity 7055 7055 7055 7055 7055 7055 Percent of Capacity 12 % 15 % 17% 20% 23% 25% 33 - DRAINAGE COMPUTATIONS for Grading Plan of Lot 2 -Block 1 Brown Addition 1.61 Acre Tract ROBERT STEVENSON LEAGUE College Station, Brazos County, T exas Pr ena red for .. v Dillard Construction 13383 Highway 30 College Station, Texas 77845 Prepared by: Garrett Engineering 4444 Carter Creek Parkway -Suite 108 Bryan, Texas 77802 Telephone: (409) 846-2688 *May, 1995 * DRAINAGE COMPUTATIONS fora Grading Plan Lot 2 -Block 1 -Brown Addition College Station, Brazos County, Texas *May, 1995 * SUMMARY The project is situated on the north side of Graham Road, approximately 1850 feet northeast along Graham Road from State Farm Road 2154 . Lot 2 -Block 1 consists of a 1.61 acre tract in the Robert Stevenson League. The total drainage area tributary to the project is 1.61 acres . The pre-development run-off coefficient was estimated to be 0.40, while taking into account typical commercial site improvements would result in a post-development run-off coefficient of 0.58. A detention facility will be constructed in the southwest portion and along the west side of t11e property . The detention pond is designed to facilitate up to and including the 100-year storm event, and discharge at a rate less than the current pre-development peak discharge rate. The detention pond will intercept, store and control the run-off from 0.74 acres of the project. The run-off generated on the remaining 0 .89 acres will "free-flow" across the project site umnetered off t11e property . TI1ese report calculations are summarized according to t11e following met110dology. Beginning on page 1, based on t11e total tributary drainage area of tlle project (being estimat d at 1.61 acres), the pre- development run-off coefficient (being assumed at 0.40), and a minimum time of concentration of 10 minutes, tlle relative pre-development peak discharge rate ("Q") was determined. The Rational Metllod was utilized to compute t11e estimated peak pre-development discharge rates. The equation tlrnt re presents the Rational Method is as follows : Q = CIA. "Q" is tlle peak discharge rate in cubic feet per second, "C" is tlle run-off coefficient, assumed to be 0.40 in the pre-development condition, "I" is tlle storm intensity in inches per hour, ~md "A" is U1e area of t11e drainage basin in acres. Computations on page 2 are based on the tributary area of 1.61 acres, the post-development run-off coefficient of 0.58 (being weighted according to U1e relative amounts of pervious and impervious surface area), a minimum time of concentration of 10 minutes, to yield the relative pre-development peak discharge rate ("Q") (assuming the same minimum time of concentration of 10 minutes). The Rational Method was again utilized to compute the estimated peak post-development discharge rates. The equation that represents the Rational Method is as follows : Q = CIA , where; "Q" is tlle peak discharge rate in cubic feet per second. The "C" variable is the run-off coefficient. (In the post-development condition "C" is assumed to be 0.58.) "I" represents t11e rainfall intensity in inches per hour, and similarly "A" is the area of t11e basin in acres. Comparison of the peak pre-d e velopment discharge rate to tlle post-development discharge rate is included in t11e report to aid tlle designer in establishing a preliminary "target" of detention volume required. This preliminary estimate is determined as the volume difference generated between tlle pre- development and post-development hydrographs. (See pag es 9-11 for pre-development and post- development hydrographs.) Please note tllat the post-development hydrograph shown on tllese same graphs assumes no detention and reflects the "worst-case" scenario tllat all run-off is allowed to free-flow. Pages 3 and 4 provide information concerning th e post-development run-off th at is not routed th ro ugh the d etention facility ("free-flow") as well as the pos t-d evelopm ent run -off that is routed through th e de tention facility and retain ed on site. Page 5 and page 6 are tabulations of th e pre-development and the post-d evelopment hydrographs based on the computations perform ed on page 1 and page 2. Th e pos t-dev e lopment hydrograph assumes no detention to facilitate direct comparison in U1e pre -and po s t-d evelopment conditions. Page 7 and page 8 are tabul ation s of t11 e pos t-d evelopm ent hydrograph for run-off directed through the detention facility and the po s t-d evelopm ent hydro gra ph for "free-flow" from the proj ec t s ite. Computations on page 4 detennine th e actual peak pos t-d evelopment "inflow" rate supplied to the proposed detention facility . From this "inflow" rate and the tim e of concentration (10 minutes minimum), a hydrograph as tabulated on page 8 is derived. The hydro graph is triangular in shape and is b ased on the standard SCS unit hydrograph wit11 time to peak set equal to the time of concentration and the total time base set at 3 .00 times the tim e of concentration. Please note that a 30 minute total storm event duration was utilized exclusively tluou ghout t11is report due to t11 e relative small s ize of the proj ect. Having derived t11 e preliminary volwn e requirements a nd "allowable peak" discharge rate, 1t 1s now possible to des ign t11 e fin a l de tention facility and outlet co ntrol structure. Page 12 presents a data tabulation and a depth versus volwne graph of th e de te ntion fac ility . The m aximum depth of the pond was set at 1.18 feet. (With th e top of berm e levation at 315.50 ft. less flow line "out" of outlet control structure at 314.32 ft.: 315 .50' -314.32' = 1.18' ). Page 13 supplies a tabulation and a rating curve for the propo sed outl e t control structure. A rectangular we ir was cho sen due to deptl1 verses discharge ratio characteristics associated wit11 t11 e anticipated shallow h ead water de pth. An ultimate storage depth of 1.18 is available due to t11 e physical geometry of the pond . However, even at 100-year s tonn conditions, depths of less tllan 1 foot are anticipated. The weir widtll was fixed at 3.00 feet. The equation used to determine discharge was Q = CLH3/2 where "Q" is the di scharge rate in cubic feet per seco nd . "C" is t11 e coefficient of di scharge, in t11is case assum ed to be set at 3 .000. "L" is th e widtll of th e weir in feet, in t11i s case ass um ed to be set at 3.0'. "H" is th e headwate r depth in feet and ranges from 0 ft. to a maximum of 1.18 ft. Page 14 presents a tabulation of t11 e relations hip between discharge from th e detention facility and the dim ensionless quantity 2S/t+O. Al so presented is a Storage Indication Curve for the de tention facility based on t11 e aforementioned physical characteristics of Ul e detention pond, storage volume, inflow hydrograph, and rating curve for t11 e outlet structure. Th e s torage indication curve as s hown on page 12 is a grap hical solution to th e equation presented in tJ1 e "Drainage Policy And Des ign Standards " as follows: 2s 1 (I 1 + 12) + (--------------- dt 2s2 -01) = (-----------------+ 02) dt Page 15 tJ1rou g h pa ge 26 present simulations of Ul e 2, 5, 10, 25, 50, and 100 year s torm events. The fir st page of each s tonn s imul a tion re presents Ul e tab ulated data for ilie s to nn event. The maximum de pth achieved in th e de tention pond durin g each s imul atio n is s hown below, as is the tim e a t during which this maximum dep ili occurs from tJ1 e onset of Ul e storm event. The calculated peak di scharge rate corresponding to thi s de pili over same period is also sho wn below. Additionally, tJ1 e maximum water s urface elevation achieved during each event an d Ule max imum peak discharge during each event are listed below. The second page of each sto rm s imul a tion represents tJ1 e pre-development hydrograph, the pos t-dev e lopm e nt hydrograph (witJ1 no detention), tl1 e po s t-d eve lopm ent hydrog raph as routed through the detention pond , and pos t-d evelopm e nt "free-fl ow" hydro graph for each storm event. Storm (year) 2-year 5-year 10-year 25-year 50-year 100-year Max . Depth (ft) 0.38 0.42 0.45 0.49 0.53 0.54 Time Period (min) 16-17 15-19 15-19 16-19 17-18 16-19 Max. Discharge (CFS) 2.08 2.47 2.73 3.07 3.43 3.57 Max. Elev. (ft MSL) 314.70 314.74 314.77 314.81 314.85 314.86 Max Velocity (ft/sec) 1.84 1.95 2.01 2.10 2.18 2.20 Page 27 through page 32 provide total inflow/outflow hydrographs for the 2, 5, 10, 25, 50 and 100-year pre-development and post-development storm events. It can be determined from these same hydrographs that the post-development peak discharge rates have been minutely decreased from those peak pre- development discharge rates due to the incorporation of the detention facility in the post-development condition. Page 33 is a graphical representation and tabulation of U1e detention pond storage volwnes as a percent of the maximum volwne of the detention pond. Also shown in the table is the storm depth and the storm elevation for the 2, 5, 10, 25, 50, and 100-year storms. The storm depth is the deepest the water will get at the flow line out of the detention pond. The stonn depth is added to the elevation of the flow line out of U1e detention pond to get the stonn elevation. A height of 0.5 feet for the freeboard can be added to the storm elevation to get a minimum berm height. The berm height in this project (315.50'), exceeds the addition of 0.5' to U1e storm elevation (314.86' + 0.5' = 315.36'). Total post-development peak discharge rates from U1e detention pond outlet control structure and project site are kept less than the pre-development peak discharge rates due to the incorporation of the proposed detention facilities. Subsequent peak post-development discharge velocities projected to be within manageable limits. Determine Total Pre -Development Peak Storm Water Discharge Rates Tributary Area ("A"): 1.61 Acres Pervious Area : 1.61 Acres Impervious A rea : 0.00 Acres Run-Off Co efficient ("Cwt "): 0.40 Time Of Con centratio n {"T/c"): Woodl a nd s: Low Ele vation : High Elevation : Distance (Feet): Slope(% Grade): Velocity ("Vw"): Time: Past ures: Low Elevation : High Elevation : Distance (Fe et): Slope (% Grade): Velocity ("Vp "): Time : Pav em ents : Low Elevation : High Elevation : Distance (Feet): Slope (% Grade): Velocity ("Vpa v e"): Time : Total Travel Time : Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year : 11.1 5 100-Year: 11.64 Peak Discharge Rate ("O"): 2-Year: 4.07 5-Year: 4.95 10 -Year: 5.56 25 -Year: 6.35 50-Year: 7.18 100-Year: 7.50 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes • 0.00 0.00 0.00 0.00 0.00 Feet I Second 0.00 Minutes 10.0 0 Minutes Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour In c hes I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cub ic Feet I Seco nd Cubic Feet I Second Determine Post -development Peak Storm Water Dischar e No Detention Tributary Area ("A"): 1.61 Acres Pervious Area : 1.10 Acres Impervious Ar ea : 0.51 Acres Run-Off Co efficient ("C wt"): 0.58 Time Of Con centration ("T/c"): 1 O Minutes (Min) Hourly Int e nsity Rates ("I"): 2-Yea r: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11.15 100-Yea r: 11.64 c = 0.40 C= 0.98 Inches I Hour Inches I Hou r Inches I Hour Inches I Hou r Inches I Hour Inches I Hour Peak Disc harge Rate ("Q"): 2-Year: 5.95 Cubic Feet I Seco nd 5-Yea r: 7.23 Cubic Feet I Sec ond ' 10 -Year: 8.11 Cubic Feet I Seco nd 25-Yea r: 9.27 C ubic Feet I Sec ond 50-Year: 10.48 Cubic Feet I Second 100-Year: 10.94 Cubic Feet I Seco nd Comparison Of Predevelopment And Post-development Peak Discharge Rates Predeve lopment Post -Dev elop ment Increas e 2-Year: 4 .0 7 Ft3/sec 5.95 Ft3/sec 1.87 Ft3/sec 5-Year: 4.95 Ft3/sec 7.23 Ft3/sec 2.2 8 Ft3/sec 10-Year: 5.56 Ft3/sec 8.11 Ft3/sec 2.55 Ft3/sec 25-Year: 6.35 Ft3/sec 9.27 Ft3/sec 2.92 Ft3/sec 50-Year: 7.18 Ft3/sec 10.48 Ft3/sec 3.3 0 Ft3/sec 100-Year: 7.50 Ft3/sec 10.94 Ft3/sec 3.44 Ft3/se c Preliminary Determin ation Of Detention Pond Volume 2-Yea r: 1 .87 Ft 3/sec x (30 Mi n. x 60 Sec . I 2 ) = 1,684 Cubic 5-Yea r: 2.28 Ft 3/sec x (30 Min . x 60 Sec . I 2 ) = 2,04 8 Cubi c 10-Year: 2 .55 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 2 ,299 Cubic 25-Year: 2 .92 Ft3/sec x (3 0 Mi n. x 60 Sec. I 2 ) = 2,625 Cub ic 50-Year : 3 .30 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 2,968 Cubic 10 0-Year: 3.44 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 3,09 9 Cubic 2 Feet Feet Feet Feet Feet Feet Determine Post-Development 11 Free-Flow 11 Peak Storm Water Discharge Tributary Area ("A"): 0.89 Acres Pervious Area : 0.89 Acres Impervious Area: 0.00 Acres Run-Off Coefficient ("Cwt "): 0.40 Time Of Concentration ("T/c"): 1 O Minutes (Min) Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11 .15 100-Year: 11 .64 Peak Discharge Rate (".Q "): 2-Year : 2.25 5-Year: 2.74 10-Year: 3 .07 25-Year: 3.51 50-Year: 3.97 100-Year: 4 .14 3 C= 0.40 C= 0.98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second • /n c-he~~ h {,, udf,·(;-; e;,..,f-(;.,. J Oi ~ / Wl f;,v'11/ ti C, fw-t.t n. d rDM yArtJ/ ~r 0. 4 ··· °54M'U- ;s ~oil A W Jife,,,- yn2err~ h"""1 tnr;'· ft ~f-~ le.,. Determine Post-Development Flow Into Detention Pond Tributary Area ("A"): 0.74 Acres ' Pervious Area: 0.24 Acres Impervious Area : 0.50 Acres Run-Off Coefficient ("Cwt"): 0.66 Time Of Concentration ("T/c "): 10 Minutes (Min) 0.00 Hourly Intensity Rates ("I"): 2-Year: 6.33 5-Year: 7.69 10-Year: 8.63 25-Year: 9.86 50-Year: 11.15 100-Year: 11 .64 Peak Discharge Rate ("O"): 2-Year: 3.10 5-Year: 3 .77 10-Year: 4 .23 25-Year: 4 .84 50-Year: 5.47 100-Year: 5.71 4 C= 0.40 C= 0.98 Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Inches I Hour Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Cubic Feet I Second Pre-Development Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year {Minutes} Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.41 0.50 0.56 0.64 0.72 0.75 2 0.81 0.99 1.11 1.27 1.44 1.50 3 1.22 1.49 1.67 1.91 2.15 2.25 4 1.63 1.98 2.22 2.54 2.87 3.00 5 2.04 2.48 2.78 3.18 3.59 3.75 6 2.44 2.97 3.34 3.81 4.31 4.50 7 2.85 3.47 3.89 4.45 5.03 5.25 8 3.26 3.96 4.45 5.08 5.74 6.00 9 3.67 -r .. 4.46 7' 5.00 , 5.72 6.46 /-6.75 1/ Peak=> I 10 6.357 4.07 4.95 5.56 7 7.18 7.50 11 3.87 4.71 5.28 6.03 6.82 7.12 12 3.67 4.46 5.00 5.72 6.46 6.75 13 3.46 4.21 4.73 5.40 6.10 6.37 14 3.26 3.96 4.45 5.08 5.74 6.00 15 3.06 3.72 4.17 4.76 5.38 5.62 16 2.85 3.47 3.89 4.45 5.03 5.25 17 2.65 3.22 3.61 4.13 4.67 4.87 18 2.44 2.97 3.34 3.81 4.31 4.50 19 2.24 2.72 3.06 3.49 3.95 4.12 20 2.04 2.48 2.78 3.18 3.59 3.75 21 1.83 2.23 2.50 2.86 3.23 3.37 22 1.63 1.98 2.22 2.54 2.87 3.00 23 1.43 1.73 1.95 2.22 2.51 2.62 24 1.22 1.49 1.67 1.91 2.15 2.25 25 1.02 1.24 1.39 1.59 1.79 1.87 26 0.81 0.99 1.11 1.27 1.44 1.50 27 0.61 0.74 0.83 0.95 1.08 1.12 28 0.41 0.50 0.56 0.64 0.72 0.75 29 0.20 0.25 0.28 0.32 0.36 0.37 30 0.00 0.00 0.00 0.00 0.00 0.00 5 Post-Development Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.59 0.72 0.81 0.93 1.05 1.09 2 1.19 1.45 1.62 1.85 2.10 2.19 3 1.78 2.17 2.43 2.78 3.14 3.28 4 2.38 2.89 3.25 3.71 4.19 4.38 5 2.97 3.61 4.06 4.63 5.24 5.47 6 3.57 4.34 4.87 5.56 6.29 6.56 7 4.16 5.06 5.68 6.49 7.33 7.66 8 4.76 5.78 6.49 7.41 8.38 8.75 9 5.35 6.51 7.30 8.34 9.43 ~ 9.84 Peak=> I 10 5.95 7 7.23 7' 8.11 7 9.27 7 10.48 ,-10.94 11 5.65 6.87 7.71 8.80 9.95 10.39 12 5.35 6.51 7.30 8.34 9.43 9.84 13 5.05 6.15 6.90 7.88 8.91 9.30 14 4.76 5.78 6.49 7.41 8.38 8.75 15 4.46 5.42 6.09 6.95 7.86 8.20 16 4.16 5.06 5.68 6.49 7.33 7.66 17 3.86 4.70 5.27 6.02 6.81 7.11 18 3.57 4.34 4.87 5.56 6.29 6.56 19 3.27 3.98 4.46 5.10 5.76 6.02 20 2.97 3.61 4.06 4.63 5.24 5.47 21 2.68 3.25 3.65 4.17 4.71 4.92 22 2.38 2.89 3.25 3.71 4.19 4.38 23 2.08 2.53 2.84 3.24 3.67 3.83 24 1.78 2.17 2.43 2.78 3.14 3.28 25 1.49 1.81 2.03 2.32 2.62 2.73 26 1.19 1.45 1.62 1.85 2.10 2.19 27 0.89 1.08 1.22 1.39 1.57 1.64 28 0.59 0.72 0.81 0.93 1.05 1.09 29 0.30 0.36 0.41 0.46 0.52 0.55 30 0.00 0.00 0.00 0.00 0.00 0.00 6 Post-Development "Free-Flow" Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.23 0.27 0.31 0.35 0.40 0.41 2 0.45 0.55 0.61 0.70 0.79 0.83 3 0.68 0.82 0.92 1.05 1.19 1.24 4 0.90 1.10 1.23 1.40 1.59 1.66 5 1.13 1.37 1.54 1.76 1.98 2.07 6 1.35 1.64 1.84 2.11 2.38 2.49 7 1.58 1.92 2.15 2.46 2.78 2.90 8 1.80 2.19 2.46 2.81 3.17 3.31 9 2.03 :;:r 2.46 /-2.77 .,....<. 3.16 ..,;;;;; 3.57 Peak=> r 10 7 -2.g§__ 2.74 3.Q?_ 3.51 3.9~ 11 2.14 2.60 2.92 3.34 3.77 3.94 12 2.03 2.46 2.77 3.16 3.57 3.73 13 1.91 2.33 2.61 2.98 3.37 3.52 14 1.80 2.19 2.46 2.81 3.17 3.31 15 1.69 2.05 2.31 2.63 2.98 3.11 16 1.58 1.92 2.15 2.46 2.78 2.90 17 1.46 1.78 2.00 2.28 2.58 2.69 18 1.35 1.64 1.84 2.11 2.38 2.49 19 1.24 1.51 1.69 1.93 2.18 2.28 20 1.13 1.37 1.54 1.76 1.98 2.07 21 1.01 1.23 1.38 1.58 1.79 1.86 22 0.90 1.10 1.23 1.40 1.59 1.66 23 0.79 0.96 1.08 1.23 1.39 1.45 24 0.68 0.82 0.92 1.05 1.19 1.24 25 0.56 0.68 0.77 0.88 0.99 1.04 26 0.45 0.55 0.61 0.70 0.79 0.83 27 0.34 0.41 0.46 0.53 0.60 0.62 28 0.23 0.27 0.31 0.35 0.40 0.41 29 0.11 0.14 0.15 0.18 0.20 0.21 30 0.00 0.00 0.00 0.00 0.00 0.00 7 Post-Development Flow Routed Through Detention Pond Inflow Hydrograph Ordinates (Cubic Feet per Second) Time 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year (Minutes) Storm Storm Storm Storm Storm Storm 0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.31 0.38 0.42 0.48 0.55 0.57 2 0.62 0.75 0.85 0.97 1.09 1.14 3 0.93 1.13 1.27 1.45 1.64 1.71 4 1.24 1.51 1.69 1.93 2.19 2.28 5 1.55 1.89 2.12 2.42 2.73 2.85 6 1.86 2.26 2.54 2.90 3.28 3.42 7 2.17 2.64 2.96 3.39 3.83 4.00 8 2.48 3.02 3.39 3.87 4.37 4.57 9 2.79 3.40 3.81 4.35 4.92 5.14 I --Peak=> 10 3.10 __ 3.77 4.23 4.84 5.47 5.71 11 2.95 3.58 4.02 4.59 5.19 5.42 12 2.79 3.40 3.81 4.35 4.92 5.14 13 2.64 3.21 3.60 4.11 4.65 4.85 14 2.48 3.02 3.39 3.87 4.37 4.57 15 2.33 2.83 3.18 3.63 4.10 4.28 16 2.17 2.64 2.96 3.39 3.83 4.00 17 2.02 2.45 2.75 3.14 3.55 3.71 18 1.86 2.26 2.54 2.90 3.28 3.42 19 1.71 2.07 2.33 2.66 3.01 3.14 20 1.55 1.89 2.12 2.42 2.73 2.85 21 1.40 1.70 1.91 2.18 2.46 2.57 22 1.24 1.51 1.69 1.93 2.19 2.28 23 1.09 1.32 1.48 1.69 1.91 2.00 24 0.93 1.13 1.27 1.45 1.64 1.71 25 0.78 0.94 1.06 1.21 1.37 1.43 26 0.62 0.75 0.85 0.97 1.09 1.14 27 0.47 0.57 0.64 0.73 0.82 0.86 28 0.31 0.38 0.42 0.48 0.55 0.57 29 0.16 0.19 0.21 0.24 0.27 0.29 30 0.00 0.00 0.00 0.00 0.00 0.00 8 6 .00 ... Q) 5 .00 0... -Q) Q) 4 .00 ... 0 ....... ·-"O ..c c :J 0 3 .00 () 0 -Q) Q) V> 0) 2 .0 0 ... 0 .s::. 0 II) 1.00 0 0 .00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 2-Year Storm Even t 5 10 15 20 25 Time (Minutes) ---Pre-Development Hydrograph ----Total Post-Development Hydrograph Total Pre-Development Vs . Total Post-Development (N o Detention) Peak Discharge Rates 5-Year Storm Even t 30 8 .00 ----~---~----~---~---~---~ a; 7 .00 -----+------Fl.-,...----1-----+--------4------1 0... l 6 .00 ... . ~ :a-5 .00 1------+--,_------;1.:::-----+--'"""'""""---+------t-------1 ..c c 8 8 4 .00 +------t:i.~------:~---t-----""-c-+----"o-t-------t--------4 -Q) ~en 3 .00 +---~'-+-~----t----+--....:::......::---+-~------t------l 5 .s::. 2 .00 +----f----7'-+------t----+-----+----"'......,...-~-------l 0 II) 0 1.00 +-...,,,"----+-----+-----+-------j-----t-="'"~-----1 0 5 10 15 20 25 Time (Minutes) Pre-Development Hydrograph ----Post -Development Outflow Hydrograph Without Detention 9 30 ... Q) Q. -Q) Q) LI.. 0 ..- ·-1J .0 c ::::J 0 u 0 ....... Q) Q) Cl) O> ... 0 .s::. 0 "' i5 ... Q) Q. -Q) Q) LI.. 0 ..- ·-1J .0 c ::::J 0 u 0 ....... Q) Q) Cl) O> ... 0 .s::. 0 "' i5 9 .00 8 .00 7.00 6 .00 5.00 4.00 3.00 2 .00 1.00 0 .00 0 Total Pre-Development Vs . Total Post-Development (No Detention) Peak Discharge Rates 10 -Year Storm Ev ent 5 10 15 20 25 Time (Min ute s) 30 Pre-Development Hydrograph Post -Developm e nt Outflow Hy drogra ph Without Detention 10 .00 9.00 8 .00 7.00 6 .00 5.00 4 .00 3 .00 2.00 1.00 0 .00 0 Tota l Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 25-Year Storm Eve nt 5 10 15 20 25 Time (M inutes) 30 Pre-Development Hydrograph Post-De v elopment Outflow Hydrograph Without Detentio n 10 12 .00 ... Q) 10 .00 0... -Q) Q) 8 .00 LL. 0 ....... ·-"O ..0 c :J 0 6 .00 u 0 -Q) Q) <I) O> 4 .00 ... 0 .r:. 0 2 .00 VI 0 0 .00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 50-Year Storm Even t 5 10 15 20 25 Time (Minutes) 30 ---Pre-Development Hydrograph ----Post-Development Outflow Hydrograph Without Detention 12 .00 ... Q) 10.00 0... -Q) Q) 8 .00 LL. 0 ...... ·-"O ..0 c :J 0 6.00 u 0 -Q) Q) (/) O> 4.00 ... 0 .r:. 0 2.00 VI 0 0.00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 100-Year Storm Even t 5 10 15 20 25 Time (Minutes) Pre-Development Hydrograph ----Post-Development Outflow Hydrograph Without Detention 11 30 Detention Pond De th Vs. Volume ........ Q) Cl> u.. 1.20 1.00 0.80 ;; 0 .60 a. Cl> c 0.40 0.20 0 .00 Elevation Depth Volume (Feet) (Ft3) 314 .32 0.00 0 314.62 0.30 479 314 .75 0.43 1,067 315 .00 0.68 2 ,586 315 .25 0 .93 4,581 315.50 1.18 7 ,055 Detention Pond Depth Vs. Volume 0 l ,000 2 ,000 3 ,000 4 ,000 5 ,000 6 ,000 7 ,000 8 ,000 Detention Pond Volume (Cubic Feet) 12 Rating Curve For Outlet Control Structure Weir Length(L): 3 .00 Depth Vs. Volume Elevation Depth Discharge (Feet) Ft3/Sec 314 .32 0.00 0.00 314 .62 0 .30 1.48 314 .75 0.43 2.54 315 .00 0.68 5 .05 315 .25 0.93 8.07 315 .50 1.18 11 .54 Rating Curve For Outlet Control Structure Depth Vs. ~ Q) LL. Volume 1.20 1.00 0 .80 ;; 0.60 -+-----+-------h~---+-----+-----+--------1 -a. Q) 0 0.00 2 .00 4.00 6 .00 8 .00 10.00 12 .00 Discharge (Cubic Feet Per Second) 13 I Storage Indication Curve Depth Storage Discharge 2s/t 2slt+O (Feet) (Ft3) (Ft3/Sec) (Ft3/Sec) (Ft3/Sec) 0 .00 0 0.00 0 .00 0.00 0 .30 479 1.48 15.97 17.45 0.43 1,067 2.54 35 .57 38 .10 0.68 2 ,586 5.05 86 .20 91 .25 0.93 4 ,581 8.07 152.70 160.77 1.18 7 ,055 11.54 235 .17 246.70 Storage Indication Curve ....... "O c 0 8 .00 0 CJ) (/) ... CJ) Cl.. -CJ) CJ) u.. 6.00 0 :0 ::J u ...., CJ) 0) ... 0 .t: 4 .00 0 UI i:5 0 .00 50 .00 100 .00 150.00 200 .00 250 .00 2s/t+O (Cubic Feet Per Second) 14 Inflow I Outflow Si mu lat ion 2-Year Storm Event T ime Inflow 11+ 12 2s/t -0 2s/t+O Outflow Depth Elevation Velocity (Mi nut es) (Ft 3/Sec) (Ft3 /Sec) (Feet) (Ft/Sec) 0 0.00 0.00 0 .00 0.00 0 .00 0 .00 314 .32 0 .00 1 0.31 0 .31 0.26 0 .31 0 .03 0.02 314 .34 0.43 2 0.62 0 .93 0 .99 1.19 0 .10 0.05 314 .37 0 .67 3 0 .93 1.55 2 .11 2 .54 0 .22 0.08 314.40 0 .86 4 1.24 2 .17 3 .55 4.28 0 .36 0.12 314.44 1.03 5 1.55 2 .79 5 .27 6.35 0 .54 0 .15 314.47 1.17 6 1.86 3.41 7 .21 8.68 0 .74 0.19 314 .51 1.30 7 2 .17 4 .03 9 .34 11 .24 0 .95 0 .22 314 .54 1.42 8 2 .4 8 4 .65 11.62 13.99 1.19 0.26 314 .58 1.53 9 2 .79 5 .27 14.03 16 .89 1.43 0 .29 314 .61 1.63 10 3 .10 5.89 16.71 19.92 1.61 0.32 314 .64 1.69 11 2 .95 6.05 19 .26 22.76 1.75 0 .34 314 .66 1.74 12 2 .79 5.74 21 .27 25 .00 1.87 0 .35 314.67 1.78 13 2 .64 5.43 22.79 26 .70 1.95 0 .36 314 .68 1.80 14 2 .4 8 5.12 23 .88 2 7 .91 2 .02 0.37 314.69 1.82 15 2.33 4.81 24 .58 28 .69 2 .06 0 .37 314.69 1.83 16 2 .17 4 .50 24 .93 29 .08 2 .08 0 .38 314.70 1.84 17 2 .02 4 .19 24 .96 29 .12 2 .08 0 .38 314.70 1.84 18 1.86 3.88 24 .7 1 28 .84 2 .06 0 .37 314 .69 1.84 19 1.71 3 .57 24 .21 28 .28 2 .03 0 .37 314 .69 1.83 20 1.55 3 .26 23.49 27.47 1.99 0.37 314 .69 1.81 21 1.40 2 .95 22.55 26.43 1.94 0.36 314 .68 1.80 22 1.24 2 .64 21.44 25 .19 1.88 0 .35 314 .67 1.78 23 1.09 2.33 20 .16 23 .77 1.80 0.34 314 .66 1.76 24 0 .93 2.02 18.73 22.18 1.72 0.33 314.65 1.73 25 0 .78 1.71 17.18 20.44 1.63 0 .32 314 .64 1.70 26 0 .62 1.40 15.50 18.57 1.54 0 .31 314 .63 1.66 27 0.47 1.09 13.77 16.58 1.41 0 .29 314 .61 1.62 28 0.31 0 .78 12.08 14 .55 1.23 0 .27 314 .59 1.55 29 0.16 0.47 10.4 2 12 .55 1.06 0.24 314 .56 1.47 30 0 .00 0 .16 8 .78 10.58 0 .90 0 .21 314.53 1.39 15 6.00 5.00 ........ "O g 4.00 0 G> Cl) Qi 0... -G> G> ... 3.00 0 :0 ;:, u -~ 0 E ;:, 2.00 0 1.00 0.00 0 Inflow/Outflow Simulation 2 -Year Storm Event 5 Pre--- Developme nt Hydrograph • I I I I I I • ' ' I ' I I 10 '\ ' '\ ' '\ '\ ' 15 20 Time (Minutes) --Post-Post- Developme De velopme nt Outflow nt Outflow Hydrograph With Without Detention Detention 16 25 30 - - - - -• Post- De velopme nt 'Free- Flow' Inflow I Outflow Simulation 5-Year St orm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outf low De pt h Elevation Velocity (Minutes ) (Ft3/Sec) (Ft3/Sec) (F eet ) (FVSec) 0 0.00 0 .00 0.00 0 .00 0 .00 0.00 314 .32 0.00 1 0.38 0 .38 0.3 1 0.38 0 .03 0.02 314 .34 0.46 2 0.75 1.13 1.20 1.45 0 .12 0 .06 3 14.38 0 .72 3 1.13 1.89 2.56 3.09 0 .26 0.09 314.41 0 .92 4 1.51 2.64 4 .32 5.2 0 0.44 0 .13 314.45 1.10 5 1.8 9 3.4 0 6.41 7 .72 0 .65 0 .17 314.49 1.25 6 2.26 4.15 8.77 10 .56 0.9 0 0.21 314 .53 1.39 7 2.64 4.90 11 .35 13 .67 1.16 0 .26 314 .58 1.51 8 3 .02 5 .66 14 .13 17 .0 1 1.44 0.30 314.62 1.63 9 3.40 6.41 17.27 20.54 1.64 0.32 314.64 1.70 10 3 .77 7 .17 20 .76 24.43 1.84 0.35 314.67 1.77 11 3 .58 7 .36 24.07 28 .12 2.03 0.3 7 314.69 1.82 12 3.40 6.98 26 .69 31 .04 2 .18 0 .3 9 314.71 1.87 13 3 .21 6.60 28 .71 33 .29 2 .29 0.40 314.72 1.90 14 3.02 6.22 ·30.19 34 .94 2.3 8 0.41 314 .73 1.92 15 2.83 5.85 31 .17 36.03 2.43 0.42 314 .74 1.94 16 2.64 5.47 31 .72 36.64 2.46 0.42 314.74 1.95 17 2.45 5.09 31 .87 36 .81 2.47 0 .42 314.74 1.95 18 2.26 4.72 31 .66 36 .58 2.46 0.42 314 .74 1.95 19 2.07 4.34 31 .14 36 .00 2.43 0.42 314 .74 1.94 20 1.89 3 .96 30 .33 35 .10 2 .38 0.41 314 .73 1.93 21 1.7 0 3 .58 29 .27 33.92 2.32 0.4 1 314.73 1.91 22 1.51 3 .21 27 .98 32.48 2.25 0.40 314 .72 1.89 23 1.32 2.83 26.48 30.8 1 2.16 0 .39 314 .71 1.87 24 1.13 2.45 24.8 0 28.93 2.07 0.3 8 3 14 .70 1.84 25 0.94 2.07 22.95 26.87 1.96 0.36 3 14 .68 1.81 26 0.75 1.70 20.95 24.65 1.85 0.35 314 .67 1.77 27 0.57 1.32 18 .82 22.2 7 1.73 0 .33 3 14 .65 1.73 28 0.38 0.94 16.57 19.76 1.60 0.32 314.64 1.69 29 0 .19 0 .57 14.23 17 .13 1.45 0.30 314.62 1.63 30 0.0 0 0 .19 11 .97 14.42 1.22 0 .26 314 .58 1.54 17 u c 0 8.00 7.00 6.00 ~ 5.00 V) ~ ll.. Qi Q) u.. 4 .00 0 :0 ::J 0 ..._, ~ 3.00 == ::J 0 2 .00 1.00 0 .00 0 Inflow/Outflow Simulation 5-Year Storm Event I I ' I I I I I I I 5 10 15 20 25 30 Time (Minutes) Pre-----Post-Post-----·--· Post- Developme Developme Developme Developme nt nt Outflow nt Outflow nt 'Free- Hydrograph Hydrograph Wi th Flow' Without Det ention Detention 18 Inflow I Outflow Simulation 10-Year Storm Event Time Inflow 11+ 12 2s/t-0 2slt+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.42 0.42 0.35 0.42 0.04 0.03 314.35 0.48 2 0.85 1.27 1.35 1.62 0.14 0.06 314.38 0.74 3 1.27 2.12 2.88 3.46 0.29 0.10 314.42 0.96 4 1.69 2.96 4.85 5.84 0.50 0.14 314.46 1.14 5 2.12 3.81 7.19 8.66 0.73 0.19 314.51 1.30 6 2.54 4.66 9.84 11.85 1.00 0.23 314.55 1.44 7 2.96 5.50 12.74 15.35 1.30 0.28 314.60 1.57 8 3.39 6.35 15.97 19.10 1.56 0.31 314.63 1.67 9 3.81 7.20 19.62 23.17 1.77 0.34 314.66 1.75 10 4.23 8.05 23.66 27.67 2.00 0.37 314.69 1.82 11 4.02 8.26 27.48 31.92 2.22 0.39 314.71 1.88 12 3.81 7.83 30.52 35.31 2.39 0.41 314.73 1.93 13 3.60 7.41 32.88 37.93 2.53 0.43 314.75 1.96 14 3.39 6.99 34.62 39.86 2.62 0.44 314.76 1.99 15 3.18 6.56 35.82 41.18 2.68 0.45 314.77 2.00 16 2.96 6.14 36.52 41.96 2.72 0.45 314.77 2.01 17 2.75 5.72 36.77 42.23 2.73 0.45 314.77 2.02 18 2.54 5.29 36.61 42.06 2.72 0.45 314.77 2.01 19 2.33 4.87 36.09 41.48 2.70 0.45 314.77 2.01 20 2.12 4.45 35.23 40.53 2.65 0.44 314.76 2.00 21 1.91 4.02 34.07 39.25 2.59 0.44 314.76 1.98 22 1.69 3.60 32.64 37.67 2.52 0.43 314.75 1.96 23 1.48 3.18 30.97 35.81 2.42 0.42 314.74 1.94 24 1.27 2.75 29.10 33.72 2.31 0.40 314.72 1.91 25 1.06 2.33 27.04 31.43 2.20 0.39 314.71 1.87 26 0.85 1.91 24.81 28.94 2.07 0.38 314.70 1.84 27 0.64 1.48 22.42 26.29 1.93 0.36 314.68 1.80 28 0.42 1.06 19.91 23.48 1.79 0.34 314.66 1.75 29 0.21 0.64 17.27 20.54 1.64 0.32 314.64 1.70 30 0.00 0.21 14.52 17.48 1.48 0.30 314.62 1.64 19 9 .00 8 .00 7.00 1' c: 6.00 0 0 Q) (/') a; Q.. 5 .00 Qi Q) LL. 0 :0 ::J 4.00 u -~ 0 =§ 3 .00 0 2 .00 1.00 0.00 Inflow/Outflow Simulation 10-Year Storm Event 0 5 Pre--- Developme nt Hydrograph I I - I I I I - I I I 10 ' ' ' ' ' ' ' 15 Time (Minutes) Post- Developme nt Outflow Hyd rograph Without De t e ntion 20 20 25 Post --------- Developme nt Outflow With Detention 30 Post- Developme nt "Free- Flow" Inflow I Outflow Simulation 25-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.48 0.48 0.40 0.48 0.04 0.03 314.35 0.50 2 0.97 1.45 1.54 1.85 0.16 0.07 314.39 0.78 3 1.45 2.42 3.29 3.96 0.34 0.11 314.43 1.00 4 1.93 3.39 5.54 6.67 0.57 0.16 314.48 1.19 5 2.42 4.35 8.22 9.89 0.84 0.21 314.53 1.36 6 2.90 5.32 11.24 13.53 1.15 0.25 314.57 1.51 7 3.39 6.29 14.56 17.53 1.48 0.30 314.62 1.64 8 3.87 7.25 18.41 21.82 1.70 0.33 314.65 1.72 9 4.35 8.22 22.73 26.63 1.95 0.36 314.68 1.80 10 4.84 9.19 27.48 31.92 2.22 0.39 314.71 1.88 11 4.59 9.43 31.96 36.91 2.48 0.42 314.74 1.95 12 4.35 8.95 35.56 40.90 2.67 0.44 314.76 2.00 13 4.11 8.46 38.39 44.03 2.82 0.46 314.78 2.04 14 3.87 7.98 40.52 46.37 2.93 0.47 314.79 2.06 15 3.63 7.50 42.00 48.01 3.01 0.48 314.80 2.08 16 3.39 7.01 42.91 49.01 3.05 0.49 314.81 2.09 17 3.14 6.53 43.29 49.44 3.07 0.49 314.81 2.10 18 2.90 6.05 43.20 49.34 3.07 0.49 314.81 2.10 19 2.66 5.56 42.68 48.76 3.04 0.49 314.81 2.09 20 2.42 5.08 41.77 47.76 2.99 0.48 314.80 2.08 21 2.18 4.59 40.51 46.36 2.93 0.47 314.79 2.06 22 1.93 4.11 38.93 44.62 2.85 0.46 314.78 2.04 23 1.69 3.63 37.06 42.56 2.75 0.45 314.77 2.02 24 1.45 3.14 34.93 40.20 2.64 0.44 314.76 1.99 25 1.21 2.66 32.57 37.59 2.51 0.43 314.75 1.96 26 0.97 2.18 30.01 34.74 2.37 0.41 314.73 1.92 27 0.73 1.69 27.29 31.71 2.21 0.39 314.71 1.88 28 0.48 1.21 24.40 28.49 2.05 0.37 314.69 1.83 . 29 0.24 0.73 21.38 25.13 1.87 0.35 314.67 1.78 30 0.00 0.24 18.24 21.63 1.69 0.33 314.65 1.72 21 ........ "U c 0 0 Cl> (/) .... Cl> Q., -; Cl> u.. 0 :0 :J () ....., ~ 0 E :J 0 10.00 9 .00 8 .00 7.00 6.00 5.00 4 .00 3 .00 2 .00 1.00 0 .00 Inflow/Outflow Simulation 25-Year Storm Event I I I I 0 5 Pre----- Developme nt Hydrog raph I I I I • ' I ' ' 10 ' " " ' " " " 15 20 Time (Minutes) Post-Post- Developme Developme nt Outflow nt Outflow Hydrograph With Without De t ention Detention 22 25 -------- 30 Post- Developme nt "Free- Flow· Inflow I Outflow Simulation 50-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 1 0.55 0.55 0.45 0.55 0.05 0.03 314.35 0.52 2 1.09 1.64 1.74 2.09 0.18 0.07 314.39 0.81 3 1.64 2.73 3.71 4.47 0.38 0.12 314.44 1.04 4 2.19 3.83 6.26 7.54 0.64 0.17 314.49 1.24 5 2.73 4.92 9.29 11.18 0.95 0.22 314.54 1.42 6 3.28 6.01 12.71 15.30 1.30 0.27 314.59 1.57 7 3.83 7.11 16.61 19.81 1.60 0.32 314.64 1.69 8 4.37 8.20 21.10 24.81 1.86 0.35 314.67 1.77 9 4.92 9.29 26.11 30.39 2.14 0.38 314.70 1.86 10 5.47 10.39 31.58 36.50 2.46 0.42 314.74 1.95 11 5.19 10.66 36.78 42.25 2.73 0.45 314.77 2.02 12 4.92 10.11 40.99 46.89 2.95 0.48 314.80 2.07 13 4.65 9.57 44.30 50.55 3.13 0.49 314.81 2.11 14 4.37 9.02 46.81 53.32 3.26 0.51 314.83 2.14 15 4.10 8.47 48.59 55.28 3.35 0.52 314.84 2.16 16 3.83 7.93 49.70 56.51 3.41 0.52 314.84 2.17 17 3.55 7.38 50.21 57.08 3.43 0.53 314.85 2.18 18 3.28 6.83 50.18 57.05 3.43 0.53 314.85 2.18 19 3.01 6.29 49.66 56.47 3.40 0.52 314.84 2.17 20 2.73 5.74 48.69 55.40 3.35 0.52 314.84 2.16 21 2.46 5.19 47.32 53.88 3.28 0.51 314.83 2.14 22 2.19 4.65 45.58 51.97 3.19 0.50 314.82 2.12 23 1.91 4.10 43.51 49.68 3.08 0.49 314.81 2.10 24 1.64 3.55 41.14 47.07 2.96 0.48 314.80 2.07 25 1.37 3.01 38.51 44.15 2.82 0.46 314.78 2.04 26 1.09 2.46 35.62 40.97 2.67 0.45 314.77 2.00 27 0.82 1.91 32.52 37.53 2.51 0.43 314.75 1.96 28 0.55 1.37 29.24 33.88 2.32 0.41 314.73 1.91 29 0.27 0.82 25.81 30.06 2.13 0.38 314.70 1.85 30 0.00 0.27 22.24 26.08 1.92 0.36 314.68 1.79 23 12 .00 10 .00 s 5 8 .00 0 Q) Cl> a; ll.. -Q) Q) LL. 6 .00 0 :a ;::, u ........ ?:: 0 s: ;::, 4 .00 0 2 .00 0 .00 Inflow/Outflow Simulation 50-Year Storm Event I • I I I 0 5 Pre----- Developme nt Hydrograph I I I ' ' ' ' I ' 10 ' ' ' ' 15 20 Time (Minutes) Post-Post- Developme Developme nt Outflow nt Outflow Hydrograph With Without Detention Detention 24 25 .... -... 30 Post- Developme nt 'Free- Flow· Inflow I Outflow Simulation 100-Year Storm Event Time Inflow 11+ 12 2s/t-0 2s/t+O Outflow Depth Elevation Velocity (Minutes) (Ft3/Sec) (Ft3/Sec) (Feet) (Ft/Sec) 0 0.00 0.00 0.00 0.00 0.00 0.00 314.32 0.00 0.57 0.57 0.47 0.57 0.05 0.03 314.35 0.53 2 1.14 1.71 1.82 2.19 0.19 0.08 314.40 0.82 3 1.71 2.85 3.88 4.67 0.40 0.12 314.44 1.06 4 2.28 4.00 6.54 7.87 0.67 0.18 314.50 1.26 5 2.85 5.14 9.70 11.68 0.99 0.23 314.55 1.44 6 3.42 6.28 13.27 15.97 1.35 0.28 314.60 1.60 7 4.00 7.42 17.40 20.69 1.64 0.32 314.64 1.70 8 4.57 8.56 22.13 25.96 1.92 0.36 314.68 1.79 9 5.14 9.70 27.40 31.83 2.22 0.39 314.71 1.88 10 5.71 10.84 33.16 38.24 2.54 0.43 314.75 1.97 11 5.42 11.13 38.63 44.29 2.83 0.46 314.78 2.04 12 5.14 10.56 43.06 49.19 3.06 0.49 314.81 2.09 13 4.85 9.99 46.57 53.05 3.24 0.51 314.83 2.13 14 4.57 9.42 49.22 55.98 3.38 0.52 314.84 2.16 15 4.28 8.85 51.11 58.07 3.48 0.53 314.85 2.19 16 4.00 8.28 52.30 59.38 3.54 0.54 314.86 2.20 17 3.71 7.71 52.86 60.00 3.57 0.54 314.86 2.20 18 3.42 7.13 52.85 60.00 3.57 0.54 314.86 2.20 19 3.14 6.56 52.33 59.42 3.54 0.54 314.86 2.20 20 2.85 5.99 51.34 58.32 3.49 0.53 314.85 2.19 21 2.57 5.42 49.92 56.76 3.42 0.52 314.84 2.17 22 2.28 4.85 48.13 54.78 3.32 0.51 314.83 2.15 23 2.00 4.28 45.98 52.41 3.21 0.50 314.82 2.13 24 1.71 3.71 43.52 49.69 3.08 0.49 314.81 2.10 25 1.43 3.14 40.78 46.66 2.94 0.47 314.79 2.07 26 1.14 2.57 37.78 43.35 2.79 0.46 314.78 2.03 27 0.86 2.00 34.54 39.77 2.62 0.44 314.76 1.99 28 0.57 1.43 31.11 35.97 2.43 0.42 314.74 1.94 29 0.29 0.86 27.52 31.97 2.22 0.39 314.71 1.88 30 0.00 0.29 23.79 27.81 2.01 0.37 314.69 1.82 25 12.00 10.00 B' 5 8 .00 0 Q) (f) Q; a.. -Q) Q) u.. 6.00 0 15 :J 0 ....... ~ 0 E :J 4 .00 0 2 .00 0 .00 Inflow/Outflow Simulation 100-Year Storm Event I ' I I ' I I ' • I ' I I ' I 0 5 10 15 20 25 30 Time (Minutes) Pre-----Post-Post-........... Post- Developme Developme Developme Developm e nt nt Outflow nt Outflow nt "Free- Hydrograph Hydrograph Wi th Fl ow" Without Detention Detention 26 Inflow/Outflow Simulation 2-Year Storm Event 4 .50 4 .00 3.50 --3.00 ,, c 0 0 Q) V) ~ Q) 2.50 Q. -Q) Q) ~ 0 :.0 2.00 :J u ..._, ~ 0 E :J 0 1.50 l.00 0 .50 0.00 0 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Tota l Post-Development Hyd rograph 27 • lnflow/Outtlow Simulation 5-Year Storm Event 5.00 4.50 4.00 3.50 ........ "O c 0 0 QI 3 .00 (/) ... QI a. -QI QI 2 .50 LL. 0 :0 ::::J () -~ 2 .00 0 E ::::J 0 1.50 1.00 0.50 0 .00 0 5 10 15 20 25 30 Time (Minutes) ---Pre-Development Hydrograph ----Total Post-Development Hydrograph 28 Inflow/Outflow Simulation 10-Year Storm Event 1i' 4 .00 c 0 0 Cl> en -Cl> 0... -Cl> Cl> 3.00 LL. 0 :0 :J (j ....... 3'; 0 = :J 0 2.00 0 5 10 15 20 25 30 Time (Minutes) Pr e -D evelopment Hydrogra ph ----Tot al Post-Deve lo pm ent Hydrogra ph 29 Inflow/Outflow Simulation 25-Year Storm Event 7 .00 6 .00 5 .00 ""' 'U c: 0 0 Q) Cl) ... 4 .00 Q) 0... -Q) Q) LL. 0 :0 ::J () 3 .00 ......., ~ 0 == ::J 0 2 .00 1.00 0 .00 0 5 10 15 20 25 30 Time (Minutes) Pre -Development Hydrograph ----Tota l Post-Development Hydrograph 30 Inflow/Outflow Simulation 50-Year Storm Event 8 .00 7.00 6 .00 ....... "O c 0 5 .00 0 Q) Cl) ... Q) 0.. -Q) Q) 4 .00 u.. 0 :0 :::J u -~ 0 3.00 E :::J 0 2.00 1.00 0 .00 0 5 10 15 20 25 30 Time (Minutes) ---Pre-Development Hydrograph ----To t a l Post-Develo pment Hydrograph 31 Inflow/Outflow Simulation 100-Year Storm Event 8.00 7.00 6 .00 ....... "O c: 0 5.00 0 Cl> Cl) ... Cl> Q., -Cl> Cl> 4 .00 LL. 0 :0 j u ....... ~ 0 3.00 E j 0 2 .00 1.00 0.00 0 5 10 15 20 25 30 Time (Minutes) ---Pre-Development Hydrograph ----Total Post-Developm ent Hydrograph 32 Detention Pond Storage Volumes as Percent of Maximum Volume 100% 90% 80% 70% Q) E ::::J 0 60% > E ::::J E ')( 50% 0 ~ 0 -40% c Q) 0 -Q) Q.. 30% 20% 10% 0% 2-year 5-year 10-year 25-year 50-year 100-year Design Storm Storm Simulation Synopsis 2-ear 5-ear 10-ear 25-ear 50-ear 100-ear Storm Depth 0.38 0.42 0.45 0.49 0.53 0.54 Storm Elevation 314 .7 0 314.74 314.77 314.81 314 .85 314.86 Storm Volume 824 1033 1199 1422 1650 1736 Maximum Capacity 7055 7055 7055 7055 7055 7055 Percent of Capacity 12 % 15 % 17% 20% 23% 25% 33 ACCOUNT NO .------------------365229 CITY OF COLLEGE STATION $____.\:::r(.~--t~--~ RECEIVEDOF_~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-·1 -9-~---FOR==-~t-;1;~~~~~--;)-;~~~-=---------======= Pa id by Check _:....V __ Cash ---THANK YOU ;., ' Figure XII-1 Application Form Development Permit For Areas Outside · Flood Hazard Areas City of College Station, Texas (re: Ordinance No .172~g ) Site Legal Oe'Ziption: lA 2, ~\CC C>VE. 1 ~ A-o121-n o"-J Site Addressj\-.-U .... tJ~W""""""'6W~l,...J,___ ________________ _ Located in: LI C\:'.: C..~ Watershed Hc.UA'(~ Dt~ l-:?3~~ Hl~l+-wA'< :3o Owner: ~u.Jtr?Q ~o;.J Address:~~ 2IllrJ.r:t:d. ~"??us;­Telephone~X::1 iEOk7k- -~~c~ PATuc.wAY Su,~ 10~ Architect/ ~~ ~~,.Je:eeu.JCt Address: eyt~~..::;l."1~~:(2 Engineer: ~ G12£.ro=, pE.') Telephone No.: (4{ii)jlfl,'..Zl;~z I"?'?~? Hi4Lk,vA\" '?O Contractor: ])ULt\1?{? <Zrm,C,W4/4DDN Address: ~i= s~~-. ~ 771¥fo/ Telephone No.:>< 77(;bd£LZ . Date Application Filed: Approved: Application is hereby made for the .f""qe Gtll!' G!'.2.dtj:>I ill,. following development: IA>!' 4 gg ~J\OliSjO \IV~~ Wtn±~ Attached as part of this application: ~ Application Fee · Drainage Pian with supporting documentation: two copies of each X Other: ~PrV Cen:JJ?..at.. ~ ACKNOWLEDGEMENTS: I, f1c..J...1.A'l'T':£?t>) 1)11,JreJ) , as owner, hereby acknowledge or affirm that: The above Drainage Plan and supporting documents complies with the requirements of Ordinance No. ll?b C-9-9s: 98