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HomeMy WebLinkAbout18 Development Permit 568 ABC Pest ControlDEVELOPMENT PERMIT PERMIT NO. 568 ABC Pest Control FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: SITE ADDRESS: 0 .63 acres within Lot 1, Block B ofReplat of Shenandoah Phase I OWNER: ABC Pest Control 1501FM2818 Suite 306 College Station, Texas 77845 361-0500 DRAINAGE BASIN: Bee Creek Main -Segment ill TYPE OF DEVELOPMENT: This permit is valid for ONLY site clearing and rough grading as shown on the partially approved construction plans dated April 24, 1998. The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate construction site in accordance with the approved erosion control plan as well as the City of College Station Drainage Policy and Design Criteria. The Owner and/or Contractor shall assure that all disturbed areas are sodden and establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion control. The Owner and/or Contractor shall also insure that any disturbed vegetation be returned to its original condition, placement and state. The Owner and/or Contractor shall be responsible for any damage to adjacent properties, city streets or infrastructure due to heavy machinery and/or equipment as well as erosion, siltation or sedimentation resulting from the permitted work. Any trees required to be protected by ordinance or as part of the landscape plan must be completely fenced before any operations of this permit can begin. This permit, being temporary, is valid only within 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 considered 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 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 above named pro·ect and all of the codes and ordinances o e City of ollege Station that apply. Date Date t:l~1 /<J<t= Date ~ I DEVELOPMENT PERMIT PERMIT NO . 568 - A ABC Pest Control FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: SITE ADDRESS: 0 .63 acres within Lot 1, Block B ofReplat of Shenandoah Phase I OWNER: ABC Pest Control 1501FM2818 Suite 306 College Station, Texas 77845 361-0500 DRAINAGE BASIN: Bee Creek Main -Segment ill TYPE OF DEVELOPMENT: This permit ;s valid for construction a~ shown on the approved construction plans. . . /1 fn v"""" No llJorJ< iw7x"Po} r<ow t+/lo w~/ w)o 71' ~T P€rm/i A-Pf'roV'e-Ol • (.2_1'-·) The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate construction site in accordance with the approved erosion control plan as well as the City of College Station Drainage Policy and Design Criteria. The Owner and/or Contractor shall assure that all disturbed areas are sodden and establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion control. The Owner and/or Contractor shall also insure that any disturbed vegetation be returned to its original condition, placement and state . The Owner and/or Contractor shall be responsible for any damage to adjacent properties, city streets or infrastructure due to heavy machinery and/or equipment as well as erosion, siltation or sedimentation resulting from the permitted work. Any trees required to be protected by ordinance or as part of the landscape plan must be completely fenced before any operations of this permit can begin . 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 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 above named project and all of the codes and ordinances e c · o liege Station that apply . _9 ~ Date Date / / ,,. "!- -.. ·0·409 764 3496 DEVELOPMENT SVCS @002 Figure Xll Development. Permit City of College Station, Texas Site Legal Description: 'Srrt£-7 G@1Jc. f(ar~ {o iZ--AfL --=Btsr &~{ Site Owner: ABL :fus-T (1Jr~I Address: l~G I f M. 2¥/~ "SJ~ Jf:l, Telephone : 5(ot -O~eo Archilecr/ /I Engineer: _c,_~__,_-'~_&_. _____ _ Address #1/ , ~ 7>4«( .#;olr TelephoneNo : __ -_ _K_ Contractor: ~8J:, lhl!J {f;;rJs. I ~~!. .C./ I 1. ~,.(; -;-rx . Address: lwu-fZ., ~M,f)r./ f!1,i_f.,__:J;379 Telephone No: 2Yl -797-1.o//'/ Date Application Filed : _/L... ... _UJ_ ....... '7 ..... Z....._ __ _ Approved : ------____ _ Application is hereby made for the following devel~pmenc specific waterway alterations : Sm£-. G 12.A-""bJc. f IAJ -&torn~ 'Aooo £\er 1 ,J Ari-r<-tir ff' Application Fee 0 Signed CeC'tificac ion s ~ Drainage and erosion control plan , with supporting Drainage Report two (2} copies each. ~ Site and Construction Plans, with supporting Drainage Report two (2} copies each. 0 Other: M5fbri.--:YI~ Jlrx1J ~ ·.·· ACKNOWLEDGMENTS : r.1JoJ1B td qaw~-H-design engineer/~. hereby acknowledge or affirm that : The information and conclusions contained in the above plans and supporting documents comply with the current requirements of the City of College Station, Texas City Code, Chapter 13 and its associated Drainage Policy and Design Standards. U.U 17 /!HS 10 : lJ '0'409 764 J496 DEVELOPMENT SVCS i4J OOJ -' I .._ Figure XH Conrinued CERTlFlCATIONS : (fo r proposed alterations within designated flood hazard areas .) A . I, certify that any nonresidential srructurc on or proposed to be on this site as part of this applicaLion is designated to prevent damage to the structure or its contents as a result of flooding from the 100 year stonn . Engineer Date B . I, certify thal the finished floor elevation of the lowest floor, including any basement, of any residential structure, proposed as part of this application is at or above the base flood elevllt ion established in the latest Federal Insurance Administration Flood Hazard Study and maps, as amended . Engineer Date C . I, certify rhat the alterations or development covered by this permit shall not diminish the flood-carrying capacity of the waterway adjoining or crossing this permitted site and that such alterations or development are consistent with requirements of the City of College Station City Code, Chapter 13 concerning encroachments offloodways and of floodway fringes . Engineer Date I, do certify that the proposed alterations do not raise the level ... ' of the I 00 year flood above elevation established in the latest Federal Insurance Administration Flood Hazard Study. Engineer Date Cond itions or comments as pan of approval. --------------------- In accordance with Chapter 13 of the Code of Ordinances of the Cily of College Station, measures shall be taken to insure that debris from conslruction, erosion, and sedimentation shall not be deposited in cily streets, or existing drainage facilities . { hereby grant this permit for development. All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer for the above named project. All of the applicable codes and ordinances of the City of College Station shall apply . ... ... -···•"'"" *** CUSTO"ER RECEIPT *** OPER: llRODGERS CT DRAWER: 1 DATE: 4/28/98 00 RECEIPT: 0011465 DESCRIPTION QTY A"OUHT TP T" ( ·.l!!SC EHGR CHARGE $100.00 3D CK 6 ~~t~r·u~~) TI"E: 15:07:50 ~ TOTAL PERSONAL CHECK $100.00 A"OUMT TENDERED $100. 00 THANK YOU P .O . Box 9960 Colle e Station, Texas 77842 Date: Number of pages including cover sheet: 3 Phone: 409-764-3570 Fax phone : Fax phone: 409-764-3496 CC: Urgent D ReplyASAP D Please comment ~~ • ltJd4z4 J ;aJ/;wut b 5k )(4/ l?ldL. If you did not receive a complete fax, please call our office immediately for a new transmittal. ' DRAINAGE COMPUTATIONS for Site & Grading Plan ABC Pest Control College Station , Brazos County, Texas Pr epared forOwner: ABC Pest Control 1501 F.M. 21818 Suite 306 College Station, Texas 77845 Pr epared by: Garrett Engineering 4444 Carter Creek Parkway -Suite 108 Bryan , Texas 77802 Telephone : ( 409) 846-2688 * Revised April 24, 1998 * REVIEWED FOR l COMPLIANCE MAY 0 1 1998 COLLEGE STATION ENB'NEER NG h./~~~ DRAINAGE COMPUTATIONS fora Site & Grading Plan For ABC Pest Control College, Brazos County, Texas *Revised April 24, 1998 * SUMMARY The project consists of a 0 .63 acre tract (Lot 1, Block "B" of a replat of Shenandoah -Phase One) situated on the west side of Texas State Highway No. 6 on the southwest comer of the intersection of Texas State Highway No. 6 west frontage road and Southern Plantation Drive. The 0.63 acre tract is the intended site for commercial development (Zoned CN) housing ABC Pest Control. A proposed 5000 square foot building is proposed which will be comprised of 4000 square feet of office space and 1000 square feet of storage space. The total drainage area tributary to the project is 0.63 acres. Only 0.38 acres of the said project tract will be developed with the remaining 0.25 acres left undisturbed. (See Exhibit "A" -Site & Grading Plan). The pre-development run-off coefficient for the 0.38 acre tract was estimated to be 0.43, while taking into account specific site improvments depicted on Exhibit "A" would result in a post-development weighted run-off coefficient of 0.84. A detention facility will be constructed within the proposed concrete drive and parking area between the proposed building and the west frontage road of Texas State Highway No. 6. The detention pond is designed to facilitate up to and including tJ1 e 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 m e ter run-off from 0.38 acres of the project (developed portion only). The run-off generated on the remaining 0 .25 acres will continue to flow in it's current manner and direction. The report calculations are sununarized according to the following methodology. Beginning on page 1, based on the total tributary drainage area of the project (being estimated at 0 .38 acres), the pre- development run-off coefficient (being assumed at 0.43), 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 0.43 in the pre-development condition, "I" is the storm intensity in inches per hour, and "A" is the area of th e drainage basin in acres. Computations on page 2 are based on the tributary area of 0.38 acres, the post-development run-off coefficient of 0 .84 (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 th a t represents the Rational Method is as follows: Q = CIA , where; "Q" is the peak di scharge 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 .84.) "I" represents tJ1e rainfall intensity in inches per hour, and similarly "A" is th e 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 detennined 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 unmetered from the project site. 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 is all of the runoff load in this case) and metered through a 12 inch 1.00 foot) wide 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 the post-development hydrograph for "free-flow" from U1e project site and run-off directed through the detention facility respectively. Computations on page 4 determine the actual peak post-development "inflow" rate supplied to the proposed detention facility. From U1is "inflow" rate and the time of concentration (10 minutes minimum), a hydrograph as tabulated on page 8 is derived. The hydro graph is triangular in shape and is based on the standard SCS unit hydrograph witil time to peak set equal to the time of concentration and the total time base set at 3.00 times tile time of concentration. Please note that a 30 minute total storm event duration was utilized exclusively throughout tilis report Having derived the preliminary volume requirements and "allowable peak" discharge rate, it is now possible to design tile final detention facility and outlet control structure. Page 12 presents a data tabulation and a depth versus volwne graph of tile detention facility. The maximum deptil of tile pond was set a 0.67 feet (8 inches). (Witil tile top of minimum curb elevation at 293.27 ft. less flow line "out" of outlet control structure at 292.60 ft.: 293.27' -292.60' = 0.68' ). Page 13 supplies a tabulation and a rating curve for tile proposed outlet control structure. A rectangular weir was chosen due to deptl1 verses discharge ratio characteristics associated witil tilis drainage scenario and headwater deptil. An ultimate storage deptil of 0.67 feet is available due to tile physical geometry of the pond. However, even at 100-year stonn conditions, runoff will be metered tilrough tile detention pond and metered off site tilrough a weir into tile existing drainage ditch located along tile west frontage road of State Highway No. 6. The weir widtil was fixed at 12 inches. The equation used to determine discharge was Q = CLH3/2 where "Q" is tile discharge rate in cubic feet per second. "C" is tile coefficient of discharge, in tilis case assumed to be set at 3.000. "L" is tlie width of tile weir in feet, in tilis case assumed to be set at 12 inches. "H'' is tile headwater deptl1 in feet and ranges from 0 ft. to a maximum of just over 0.67 ft. Page 14 presents a tabulation of tile relationship between discharge from tile detention facility and tile dimensionless quantity 2S/t-O. Also presented is a Storage Indication Curve for tile detention facility based on tile aforementioned physical characteristics of tile detention pond, storage volume, inflow hydrograph, and rating curve for tile outlet structure. The storage indication curve as shown on page 12 is a graphical solution to tile equation presented in tile "Draina~e Policy And Desi~n Standards" as follows: 2s 1 (11+12) + (----------------01) = dt 2s2 (-----------------+ 02) dt The following pages present simulations for 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 bydrograph (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 are presented on pages 27-32 . 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 t11e 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 facilities. Subsequent peak post-development discharge velocities are projected to be within manageable limits. The detention facility as designed meters the 2, 5, 10, 25, 50 and 100-year storm events without over- topping the curb. - DE!.termine Total Pre-Development Peak Storm Water Discharge Rates Tributary Area ("A"): 0.38 Acres Pervious Area : 0 .36 Acres Impervious Area : 0.02 Acres Run-Off Coefficient ("Cwt"): 0.43 Time Of Concentration ("T/c "): Woodlands: Low Elevation : High Elevation : Distance (Feet): Slope(% Grade): Veloc 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 .54 5-Year: 7 .70 10-Year: 8 .92 25-Year: 9 .92 50-Year: 11 .07 100-Year: 11 .61 Peak Discharge Rate ("Q"): 2-Year: 1.07 5-Year: 1.26 10-Yea r: 1.46 25-Year: 1.62 50-Year: 1.81 100-Year: 1.90 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 Cub ic 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"): 0.38 Acres Pervious Area : 0.09 Acres Impervious Area: 0.29 Acres Run-Off Coefficient ("Cwt"): 0.84 Time Of Concentration ("T/c"): 10 Minutes (Min) Hourly Intensity Rates ("I"): 2-Year: 6.54 5-Year: 7.70 10 -Year : 8.92 25-Year: 9.92 50-Year: 11 .07 100-Year: 11.61 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: 2.09 Cubic Feet I Second 5-Year: 2.47 Cubic Feet I Second 10-Year: 2.86 Cubic Feet I Second 25-Year: 3.18 Cubic Feet I Second 50-Year: 3 .55 Cubic Feet I Second 100-Year: 3.72 Cubic Feet I Second Comparison Of Predevelopment And Post-develo ment Peak Dischar e Rates Predevelopment Post-Development Increase 2-Year: 1.07 Ft3/sec 2.09 Ft3/sec 1.02 Ft3/sec 5-Year: 1.26 Ft3 /sec 2.47 Ft3/sec 1 .21 Ft3/sec 10-Year: 1.46 Ft3/sec 2.86 Ft3/sec 1 .40 Ft3/sec 25 -Year: 1 .62 Ft3/sec 3 .18 Ft3/sec 1 .55 Ft3/sec 50-Year: 1.81 Ft3/sec 3.55 Ft3/sec 1 . 73 Ft3/sec 100-Year: 1.90 Ft3/sec 3 .72 Ft3/sec 1.82 Ft3/sec Preliminary Determination Of Detention Pond Volume 2-Year: 1.02 Ft3/sec x (30 Min . x 60 Sec. I 2 ) = 921 Cubic 5-Year: 1.21 Ft3/sec x (30 Min . x 60 Sec. I 2 ) = 1,086 Cubic 10-Year: 1.40 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 1 ,257 Cubic 25-Year: 1.55 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 1,399 Cubic 50-Year: 1.73 Ft3/sec x (30 Min . x 60 Sec. I 2 ) = 1 ,560 Cubic 100-Year: 1.82 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 1,636 Cubic 2 Feet Feet Feet Feet Feet Feet Determine Post-Development 11 Free-Flow 11 Peak Storm Water Dischar e Tributary Area ("A"): 0 .00 Acres Pervious Area : 0.00 Acres Impervious Area: 0 .00 Acres Run-Off Coefficient ("Cwt"): 0.00 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: 0 .00 5-Year: 0 .00 10-Year: 0.00 25-Year: 0.00 50-Year: 0 .00 100-Year: 0.00 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"): 0.38 Acres Pervious Area: 0.09 Acres Impervious Area: 0.29 Acres Run-Off Coefficient ("Cwt"): 0.84 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: 2.03 5-Year: 2.46 10-Year: 2.76 25-Year: 3.16 50-Year: 3.57 100-Year: 3.73 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 0.11 0.13 0.15 0.16 0.18 0.19 2 0.21 0.25 0.29 0.32 0.36 0.38 3 0.32 0.38 0.44 0.49 0.54 0.57 4 0.43 0.50 0.58 0.65 0.72 0.76 5 0.53 0.63 0.73 0.81 0.91 0.95 6 0.64 0.76 0.88 0.97 1.09 1.14 7 0.75 0.88 1.02 1.14 1.27 1.33 8 0.86 1.01 1.17 1.30 1.45 1.52 9 0.96 1.13 1.31 1.46 1.63 1.71 Peak=> I 10 1.07 1.26 1.46 1.62 1.81 1.90 11 1.02 1.20 1.39 1.54 1.72 1.80 12 0.96 1.13 1.31 1.46 1.63 1.71 13 0.91 1.07 1.24 1.38 1.54 1.61 14 0.86 1.01 1.17 1.30 1.45 1.52 15 0.80 0.95 1.09 1.22 1.36 1.42 16 0.75 0.88 1.02 1.14 1.27 1.33 17 0.70 0.82 0.95 1.06 1.18 1.23 18 0.64 0.76 0.88 0.97 1.09 1.14 19 0.59 0.69 0.80 0.89 1.00 1.04 20 0.53 0.63 0.73 0.81 0.91 0.95 21 0.48 0.57 0.66 0.73 0.82 0.85 22 0.43 0.50 0.58 0.65 0.72 0.76 23 0.37 0.44 0.51 0.57 0.63 0.66 24 0.32 0.38 0.44 0.49 0.54 0.57 25 0.27 0.32 0.36 0.41 0.45 0.47 26 0.21 0.25 0.29 0.32 0.36 0.38 27 0.16 0.19 0.22 0.24 0.27 0.28 28 0.11 0.13 0.15 0.16 0.18 0.19 29 0.05 0.06 0.07 0.08 0.09 0.09 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 0.21 0.25 0.29 0.32 0.35 0.37 2 0.42 0.49 0.57 0.64 0.71 0.74 3 0.63 0.74 0.86 0.95 1.06 1.11 4 0.84 0.99 1.14 1.27 1.42 1.49 5 1.05 1.23 1.43 1.59 1.77 1.86 6 1.26 1.48 1.71 1.91 2.13 2.23 7 1.47 1.73 2.00 2.22 2.48 2.60 8 1.67 1.97 2.28 2.54 2.84 2.97 9 1.88 2.22 2.57 2.86 3.19 3.34 Peak=> I' 10 2.09 2.47 2.86 -3.18 3.55 3.72 11 1.99 2.34 2.71 3.02 3.37 3.53 12 1.88 2.22 2.57 2.86 3.19 3.34 13 1.78 2.10 2.43 2.70 3.01 3.16 14 1.67 1.97 2.28 2.54 2.84 2.97 15 1.57 1.85 2.14 2.38 2.66 2.79 16 1.47 1.73 2.00 2.22 2.48 2.60 17 1.36 1.60 1.86 2.07 2.30 2.42 18 1.26 1.48 1.71 1.91 2.13 2.23 19 1.15 1.36 1.57 1.75 1.95 2.04 20 1.05 1.23 1.43 1.59 1.77 1.86 21 0.94 1.11 1.29 1.43 1.60 1.67 22 0.84 0.99 1.14 1.27 1.42 1.49 23 0.73 0.86 1.00 1.11 1.24 1.30 24 0.63 0.74 0.86 0.95 1.06 1.11 25 0.52 0.62 0.71 0.79 0.89 0.93 26 0.42 0.49 0.57 0.64 0.71 0.74 27 0.31 0.37 0.43 0.48 0.53 0.56 28 0.21 0.25 0.29 0.32 0.35 0.37 29 0.10 0.12 0.14 0.16 0.18 0.19 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 0.00 0.00 0.00 0.00 0.00 0.00 2 0.00 0.00 0.00 0.00 0.00 0.00 3 0.00 0.00 0.00 0.00 0.00 0.00 4 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 0.00 0.00 0.00 0.00 0.00 6 0.00 0.00 0.00 0.00 0.00 0.00 7 0.00 0.00 0.00 0.00 0.00 0.00 8 0.00 0.00 0.00 0.00 0.00 0.00 9 0.00 0.00 0.00 0.00 0.00 0.00 Peak=> I 10 0.00 0.00 0.00 0.00 0.00 0.00 11 0.00 0.00 0.00 0.00 0.00 0.00 12 0.00 0.00 0.00 0.00 0.00 0.00 13 0.00 0.00 0.00 0.00 0.00 0.00 14 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 16 0.00 0.00 0.00 0.00 0.00 0.00 17 0.00 0.00 0.00 0.00 0.00 0.00 18 0.00 0.00 0.00 0.00 0.00 0.00 19 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0.00 0.00 0.00 21 0.00 0.00 0.00 0.00 0.00 0.00 22 0.00 0.00 0.00 0.00 0.00 0.00 23 0.00 0.00 0.00 0.00 0.00 0.00 24 0.00 0.00 0.00 0.00 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 26 0.00 0.00 0.00 0.00 0.00 0.00 27 0.00 0.00 0.00 0.00 0.00 0.00 28 0.00 0.00 0.00 0.00 0.00 0.00 29 0.00 0.00 0.00 0.00 0.00 0.00 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 0.20 0.25 0.28 0.32 0.36 0.37 2 0.41 0.49 0.55 0.63 0.71 0.75 3 0.61 0.74 0.83 0.95 1.07 1.12 4 0.81 0.99 1.11 1.26 1.43 1.49 5 1.01 1.23 1.38 1.58 1.78 1.86 6 1.22 1.48 1.66 1.89 2.14 2.24 7 1.42 1.72 1.94 2.21 2.50 2.61 8 1.62 1.97 2.21 2.53 2.86 2.98 9 1.82 2.22 2.49 2.84 3.21 3.35 Peak=> I 10 2.03 2.46 2.76 3.16 3.57 3.73 11 1.92 2.34 2.63 3.00 3.39 3.54 12 1.82 2.22 2.49 2.84 3.21 3.35 13 1.72 2.09 2.35 2.68 3.03 3.17 14 1.62 1.97 2.21 2.53 2.86 2.98 15 1.52 1.85 2.07 2.37 2.68 2.80 16 1.42 1.72 1.94 2.21 2.50 2.61 17 1.32 1.60 1.80 2.05 2.32 2.42 18 1.22 1.48 1.66 1.89 2.14 2.24 19 1.11 1.35 1.52 1.74 1.96 2.05 20 1.01 1.23 1.38 1.58 1.78 1.86 21 0.91 1.11 1.24 1.42 1.61 1.68 22 0.81 0.99 1.11 1.26 1.43 1.49 23 0.71 0.86 0.97 1.11 1.25 1.30 24 0.61 0.74 0.83 0.95 1.07 1.12 25 0.51 0.62 0.69 0.79 0.89 0.93 26 0.41 0.49 0.55 0.63 0.71 0.75 27 0.30 0.37 0.41 0.47 0.54 0.56 28 0.20 0.25 0.28 0.32 0.36 0.37 29 0.10 0.12 0.14 0.16 0.18 0.19 30 0.00 0.00 0.00 0.00 0.00 0.00 8 - y y 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 Post-Development Hydrograph Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 5-Year Storm Event 1.00 +---~-+--~~--t------"""""""':l-----t-----".....,_---t-------l O.OO-fl"-----+-----+----+---~1-----+---~ 0 5 10 15 20 25 Time (Minutes) Pre-Development Hydrograph 9 ----Post-Development Outflow Hydrograph Without Detention 30 3.00 2.50 2.00 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 10-Year Storm Event y 1.50 y 1.00 0.50 0 .00 0 5 10 15 20 25 Time (Minutes) ----Pre-Development Hydrograph ----Post-Development Outflow Hydrograph Without Detention Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 25-Year Storm Event 30 3.50-----~----~---~----~---~---~ 3.00 --------+---~'-+-'---------1-------1---------+---- 2.50 +-----j----,,__-!------3ooo.o+------l-----l----- 2.00 +------+--:1----+------+---.3oir----+-------l----- 1.50 +-----A----___,,,,e.-+-:::......~----+------?oo.~-----+-----" 1.00 +---,.--t---T'-----i!-----+-~~;;::---t-----.3oo..---I----~ 0.50 +--F~e;__-+---------1!-----+-----t---_::::,,,,,,~1--~-~ 0.00-F------...... ------~~------...... ------...... --------~----...;;;;;;Jlii 0 5 10 15 20 25 Time (Minutes) Pre-Development Hydrograph 10 ----Post-Development Outflow Hydrograph Without Detention 30 4.00 3.50 3.00 2.50 Y2 .00 1.50 1.00 0.50 0.00 0 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 50-Year Storm Event 5 10 15 20 25 Time (Minutes) ----Pre -Development Hydrograph ----Post-Development Outflow Hydrograph Wit ho ut Detention Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 100-Year Storm Event 30 4 .00----------~--------~---~---~ 3.50 1------+----#-t---"'----+-----+----1----- 3.00 1------+--+---r-------''""-::--+-----+----1----- 2.50 +------+--1---+-----+----"'---+------+---- y 2.00 +------+,,_---+-----+---~+------+---- 1.50 1----~~--.,,C..--+---~-..d-----+----3oo----l-------i 1.00 +--_,. _ __,,,£..-___ +-----+---==-.....t------=~------i 0.50 1--_,_-,;£---+----+-----+----+---..........:="""'-1.,---3io.~---i o .oo~-------+--------1i--------.._-------+-------.1i------~ 0 5 10 15 Time (Minutes) Pr e-Development Hydr ograph 11 20 25 Post -Development Outflow Hydrograph Without Detention 30 beg in ca Detention Pond De th Vs. Volume Elevation Depth Volume {Feet} {Ft3} 2-year 5-year 292.60 0.00 0 10-year 292.73 0.13 10 25-year 292.86 0.26 78 50-year 292 .99 0.39 325 100-yea 293.12 0 .52 847 293 .27 0.67 1,654 Detention Pond Depth Vs. Volume 0 .70 0 .60 / ~ / / , ~/ ~/ v 0.50 0.40 y j j( , 0.30 0.20 0 .10 0 .00 0 200 400 600 800 l ,000 l ,200 1,400 l ,600 l ,800 Detention Pond Volume (Cubic Feet) 12 Rating Curve For Outlet Control Structure Weir Length(L): 1.00 De th Vs . Volume El evat ion Depth Discharge (Feet) Ft3/Sec 292.60 0 .00 0 .00 292.73 0 .13 0.14 292.86 0.26 0.40 292 .99 0.3 9 0.73 293 .12 0.52 1.1 2 293 .2 7 0 .67 1.65 Rating Curve For Outlet Control Structure Depth Vs. Volume 0 .70 y / ,, / / ~/ , / v / v I / I 0.60 0 .50 0 .40 0 .30 0.20 0 .10 0 .00 0 .00 0 .20 0 .40 0 .60 0.80 l.00 1.20 1.40 1.60 1.80 Discharge (Cubic Feet Per Second) 13 - 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 .13 10 0.14 0 .33 0.47 0.26 78 0.40 2 .60 3 .00 0.39 325 0 .73 10 .83 11.56 0 .52 847 1.12 28 .23 29 .36 0 .67 1,654 1.65 55 .13 56 .78 Storage Indication Curve 1.80 y / / v / v / v / v / l.60 1.40 1.20 l.00 0 .80 ) I I , 0 .60 0 .40 0.20 0.00 0.00 10.00 20 .00 30 .00 40.00 50.00 60 .00 2s/t+O (Cubic Feet Per Second) 14 - Inflow I Outflow Simulation 2-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 0.00 292.60 0.00 1 0.20 0.20 0.08 0.20 0.06 0.07 292.67 0.81 2 0.41 0.61 0.36 0.69 0.16 0.14 292.74 1.14 3 0.61 1.01 0.91 1.38 0.23 0.18 292.78 1.28 4 0.81 1.42 1.67 2.33 0.33 0.23 292.83 1.44 5 1.01 1.82 2.66 3.49 0.42 0.27 292.87 1.55 6 1.22 2.23 3.95 4.89 0.47 0.29 292.89 1.62 7 1.42 2.63 5.51 6.58 0.54 0.32 292.92 1.69 8 1.62 3.04 7.32 8.54 0.61 0.35 292.95 1.77 9 1.82 3.44 9.36 10.76 0.70 0.38 292.98 1.85 10 2.03 3.85 11.68 13.21 0.77 0.40 293.00 1.90 11 1.92 3.95 13.99 15.63 0.82 0.42 293.02 1.95 12 1.82 3.75 16.00 17.73 0.87 0.44 293.04 1.98 13 1.72 3.55 17.73 19.54 0.91 0.45 293.05 2.01 14 1.62 3.34 19.19 21.07 0.94 0.46 293.06 2.04 15 1.52 3.14 20.39 22.33 0.97 0.47 293.07 2.06 16 1.42 2.94 21.34 23.33 0.99 0.48 293.08 2.07 17 1.32 2.73 22.06 24.08 1.01 0.48 293.08 2.09 18 1.22 2.53 22.56 24.60 1.02 0.49 293.09 2.09 19 1.11 2.33 22.84 24.89 1.03 0.49 293.09 2.10 20 1.01 2.13 22.91 24.96 1.03 0.49 293.09 2.10 21 0.91 1.92 22.78 24.83 1.02 0.49 293.09 2.10 22 0.81 1.72 22.47 24.50 1.02 0.49 293.09 2.09 23 0.71 1.52 21.98 23.99 1.01 0.48 293.08 2.08 24 0.61 1.32 21.31 23.29 0.99 0.48 293.08 2.07 25 0.51 1.11 20.48 22.43 0.97 0.47 293.07 2.06 26 0.41 0.91 19.50 21.40 0.95 0.46 293.06 2.04 27 0.30 0.71 18.36 20.21 0.92 0.46 293.06 2.02 28 0.20 0.51 17.08 18.87 0.89 0.45 293.05 2.00 29 0.10 0.30 15.67 17.39 0.86 0.43 293.03 1.98 30 0.00 0.10 14.12 15.77 0.82 0.42 293.02 1.95 15 y - Inflow/Outflow Simulation 2-Year Storm Event 2.50 2 .00 1.50 l.00 0.50 0 .00 0 5 -----Pre- Developm ent Hydrogra p h I I • I I I I I I I I '\, • I '\, ' ' ' .... .... .... .... .... ' .... 10 15 20 Time (Minutes) Post - Developm ent Outflow Hydr ogra ph Without Detentio n -----Post- Develo pm ent Outflow Wit h Detention 16 25 30 - - - - - - -Post- Developm ent 'Fr ee- Flow' 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 0.00 292.60 0 .00 0 .25 0 .25 0.10 0.25 0 .07 0.08 292 .68 0.87 2 0.49 0.74 0.48 0 .84 0 .18 0 .15 292 .75 1.17 3 0.74 1.23 1.18 1.72 0.27 0.20 292 .80 1.34 4 0.99 1.72 2.13 2.91 0.39 0.26 292.86 1.52 5 1.23 2.22 3.45 4.35 0.45 0.28 292 .88 1.59 6 1.48 2.71 5.11 6.15 0.52 0.31 292 .91 1.67 7 1.72 3 .20 7 .11 8.32 0 .60 0 .34 292 .94 1.76 8 1.97 3 .69 9.40 10 .80 0.70 0.38 292 .98 1.85 9 2.22 4.19 12 .04 13.59 0 .78 0.41 293.01 1.91 10 2.46 4.68 15 .03 16 .72 0 .84 0.43 293 .03 1.97 11 2.34 4.80 18 .00 19.83 0.91 0.45 293.05 2 .02 12 2.22 4.56 20 .61 22.56 0.97 0.47 293 .07 2.06 13 2.09 4 .31 22 .87 24.92 1.03 0.49 293.09 2.10 14 1.97 4 .06 24 .79 26 .93 1.07 0.50 293.10 2.13 15 1.85 3 .82 26.39 28 .61 1.11 0.51 293.11 2.15 16 1.72 3.57 27 .69 29 .96 1.14 0.52 293.12 2 .17 17 1.60 3 .33 28 .70 31 .02 1.16 0.53 293.13 2 .18 18 1.48 3 .08 29.44 31 .78 1.17 0 .53 293 .13 2.19 19 1.35 2.83 29 .91 32 .27 1.18 0.54 293.14 2.20 20 1.23 2.59 30 .13 32.50 1.18 0.54 293.14 2.20 21 1.11 2.34 30.10 32.47 1.18 0.54 293.14 2 .20 22 0 .99 2.09 29 .84 32 .20 1.18 0 .54 293 .14 2.20 23 0 .86 1.85 29.35 31 .69 1.17 0 .53 293 .13 2.19 24 0 .74 1.60 28 .64 30 .95 1.16 0.53 293.13 2.18 25 0.62 1.35 27 .72 29.99 1.14 0.52 293.12 2.17 26 0.49 1.11 26 .60 28 .83 1.11 0 .52 293 .12 2 .16 27 0 .37 0 .86 25 .30 27.46 1.08 0 .51 293 .11 2.14 28 0.25 0.62 23 .82 25 .91 1.05 0.50 293 .10 2.11 29 0.12 0 .37 22.16 24 .19 1.01 0.48 293 .08 2.09 30 0.00 0.12 20 .35 22.29 0.97 0.47 293.07 2.06 17 - y - Inflow/Outflow Simulation 5-Year Storm Event 2.50 2 .00 1.50 I 1.00 0.50 0.00 0 5 -----Pre- De velopm ent Hydr ogra ph I I • I I I I I I I I I I I ' ' ' ' ' ' 10 15 ' ' ' ' ' ' ' ' 20 Time (Minutes) Post- Developm ent Outflow Hydrogra ph Without Detention -----Post- Developm ent Outflow With Detention 18 25 30 Post- Developm ent 'Free- Flow' Inflow I Outflow Simulation t 0-Year Storm Event Time Inflow It+ 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 0.00 292.60 0.00 t 0.28 0.28 0.11 0.28 0.08 0.09 292.69 0.90 2 0.55 0.83 0.57 0.94 0.19 0.16 292.76 t.19 3 0.83 1.38 t.37 1.95 0.29 0.21 292.81 t.38 4 1.1 t t.94 2.48 3.30 0.41 0.27 292.87 t.54 5 t.38 2.49 4.02 4.97 0.47 0.29 292.89 t.62 6 t.66 3.04 5.95 7.06 0.56 0.32 292.92 1.71 7 t.94 3.59 8.24 9.55 0.65 0.36 292.96 t.80 8 2.21 4.15 10.89 12.39 0.75 0.40 293.00 t.89 9 2.49 4.70 13.95 15.59 0.82 0.42 293.02 t.95 10 2.76 5.25 17.40 19.20 0.90 0.45 293.05 2.01 tt 2.63 5.39 20.84 22.80 0.98 0.47 293.07 2.07 12 2.49 5.1 t 23.85 25.95 1.05 0.50 293.10 2.1 t 13 2.35 4.84 26.47 28.69 1.11 0.52 293.12 2.15 14 2.21 4.56 28.72 31.03 t.16 0.53 293.13 2.18 15 2.07 4.29 30.62 33.00 t.19 0.54 293.14 2.21 16 1.94 4.01 32.18 34.63 t .22 0.55 293.15 2.23 17 1.80 3.73 33.41 35.91 1.25 0.56 293.16 2.24 18 t.66 3.46 34.33 36.87 1.27 0.56 293.16 2.25 19 t.52 3.18 34.95 37.51 t.28 0.57 293.17 2.26 20 t .38 2.90 35.28 37.85 t .29 0.57 293.17 2.26 21 1.24 2.63 35.33 37.91 t .29 0.57 293.17 2.26 22 1.11 2.35 35.12 37.68 1.28 0.57 293.17 2.26 23 0.97 2.07 34.64 37.19 1.27 0.56 293.16 2.25 24 0.83 1.80 33.92 36.44 t.26 0.56 293.16 2.25 25 0.69 t.52 32.96 35.44 ~ .24 0.56 293.16 2.23 26 0.55 t .24 31.77 34.21 1.22 0.55 293.15 2.22 27 0.41 0.97 30.36 32.74 1.19 0.54 293.14 2.20 28 0.28 0.69 28.74 31.05 t.16 0.53 293.13 2.18 29 0.14 0.41 26.91 29.15 t .12 0.52 293.12 2.16 30 0.00 0.14 24.90 27.05 t.07 0.50 293.10 2.13 19 3.00 2.50 2.00 y 1.50 1.00 0.50 0.00 0 Inflow/Outflow Simulation 10-Year Storm Event 5 Pre- Develop ment Hydrogra ph I I I - I I - I I I - I I I I I - I '\. I ' ' .. ' ' ' ' ' ' ' 10 15 20 25 Time (Minutes) -Post -Post---------- De v elop Develop ment ment Outflow Outflow Hydrogra Wit h ph Detention With o ut Det ention 20 30 Post- Develop ment "Free- Flow· Inflow I Outflow Simulation 25-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 0.00 292.60 0.00 1 0.32 0.32 0.13 0.32 0.09 0.10 292.70 0.94 2 0.63 0.95 0.67 1.08 0.20 0.17 292.77 1.22 3 0.95 1.58 1.61 2.25 0.32 0.23 292.83 1.43 4 1.26 2.21 2.96 3.82 0.43 0.27 292.87 1.57 5 1.58 2.84 4.79 5.80 0.51 0.31 292.91 1.66 6 1.89 3.47 7.06 8.26 0.60 0.34 292.94 1.76 7 2.21 4.10 9.73 11.16 0.72 0.38 292.98 1.86 8 2.53 4.74 12.88 14.47 0.79 0.41 293.01 1.93 9 2.84 5.37 16.49 18.25 0.88 0.44 293.04 1.99 10 3.16 6.00 20.54 22.49 0.97 0.47 293.07 2.06 11 3.00 6.16 24.57 26.70 1.07 0.50 293.10 2.12 12 2.84 5.84 28.12 30.41 1.14 0.53 293.13 2.18 13 2.68 5.53 31.23 33.65 1.21 0.54 293.14 2.21 14 2.53 5.21 33.92 36.44 1.26 0.56 293.16 2.25 15 2.37 4.89 36.21 38.82 1.30 0.57 293.17 2.27 16 2.21 4.58 38.10 40.79 1.34 0.58 293.18 2.29 17 2.05 4.26 39.62 42.37 1.37 0.59 293.19 2.31 18 1.89 3.95 40.78 43.57 1.39 0.60 293.20 2.32 19 1.74 3.63 41.59 44.41 1.41 0.60 293.20 2.33 20 1.58 3.32 42.07 44.91 1.42 0.61 293.21 2.34 21 1.42 3.00 42.22 45.07 1.42 0.61 293.21 2.34 22 1.26 2.68 42.07 44.90 1.42 0.61 293.21 2.34 23 1.11 2.37 41.61 44.43 1.41 0.60 293.20 2.33 24 0.95 2.05 40.87 43.66 1.40 0.60 293.20 2.32 25 0.79 1.74 39.86 42.61 1.38 0.59 293.19 2.31 26 0.63 1.42 38.57 41.28 1.35 0.59 293.19 2.30 27 0.47 1.11 37.04 39.68 1.32 0.58 293.18 2.28 28 0.32 0.79 35.26 37.83 1.29 0.57 293.17 2.26 29 0.16 0.47 33.24 35.73 1.25 0.56 293.16 2.24 30 0.00 0.16 30.99 33.40 1.20 0.54 293.14 2.21 21 Inflow/Outflow Simulation 25-Year Storm Event 3.50 3.00 2.50 2.00 y 1.50 1.00 0.50 0 .00 0 5 -----Pre- Developm ent Hydrogra ph I I I I I I I I I I ' I ' 10 ' ' ' ' ' ' ' ' ' 15 ' ' ' ' ' 20 Time (Minutes) Post - Developm ent Outflow Hydrogra ph With o ut Detenti o n -----Post- Developm ent Outflow With Detention 22 25 30 Post- Developm ent 'Free- Flow ' Inflow I Outflow Simulation SO-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 0.00 292.60 0.00 1 0.36 0.36 0.15 0.36 0.11 0.11 292.71 0.98 2 0.71 1.07 0.78 1.22 0.22 0.17 292.77 1.25 3 1.07 1.78 1.86 2.57 0.35 0.24 292.84 1.47 4 1.43 2.50 3.46 4.36 0.45 0.28 292.88 1.59 5 1.78 3.21 5.59 6.67 0.54 0.32 292.92 1.69 6 2.14 3.93 8.21 9.52 0.65 0.36 292.96 1.80 7 2.50 4.64 11.34 12.85 0.76 0.40 293.00 1.90 8 2.86 5.35 15.00 16.69 0.84 0.43 293.03 1.97 9 3.21 6.07 19.19 21.07 0.94 0.46 293.06 2.04 10 3.57 6.78 23.87 25.97 1.05 0.50 293.10 2.11 11 3.39 6.96 28.52 30.83 1.15 0.53 293.13 2.18 12 3.21 6.60 32.66 35.13 1.23 0.55 293.15 2.23 13 3.03 6.25 36.29 38.91 1.31 0.57 293.17 2.27 14 2.86 5.89 39.45 42.18 1.37 0.59 293.19 2.31 15 2.68 5.53 42.14 44.98 1.42 0.61 293.21 2.34 16 2.50 5.18 44.38 47.31 1.47 0.62 293.22 2.36 17 2.32 4.82 46.20 49.20 1.50 0.63 293.23 2.38 18 2.14 4.46 47.60 50.66 1.53 0.64 293.24 2.40 19 1.96 4.10 48.61 51.71 1.55 0.64 293.24 2.41 20 1.78 3.75 49.23 52.35 1.56 0.65 293.25 2.41 21 1.61 3.39 49.49 52.62 1.57 0.65 293.25 2.42 22 1.43 3.03 49.40 52.52 1.56 0.65 293.25 2.41 23 1.25 2.68 4?.96 52.07 1.56 0.65 293.25 2.41 24 1.07 2.32 48.20 51.28 1.54 0.64 293.24 2.40 25 0.89 1.96 47.12 50.16 1.52 0.64 293.24 2.39 26 0.71 1.61 45.74 48.73 1.49 0.63 293.23 2.38 27 0.54 1.25 44.07 46.99 1.46 0.62 293.22 2.36 28 0.36 0.89 42.12 44.97 1.42 0.61 293.21 2.34 29 0.18 0.54 39.91 42.66 1.38 0.60 293.20 2.31 30 0.00 0.18 37.43 40.08 1.33 0.58 293.18 2.29 23 4 .00 3.50 3 .00 2.50 Y2.00 1.50 1.00 0.50 0 .00 0 Inflow/Outflow Simulation 50-Year Storm Event • • • • • • • • • • • • • 5 Pre ----- Developm ent Hydrogra ph . ' . ' 10 ' ' ' ' 15 Time (Minutes) -Post- Devel o pm ent Outflow Hydrogra ph Without Detention 24 ' 20 25 Post---------- Developm ent Outflow With Detent ion 30 Post- Devel opm ent 'Free- Flow' Inflow I Outflow Simulation 1 00-Y ear 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 0.00 292.60 0.00 1 0.37 0.37 0.15 0.37 0.11 0.11 292.71 1.00 2 0.75 1.12 0.83 1.27 0.22 0.18 292.78 1.26 3 1.12 1.86 1.96 2.69 0.37 0.25 292.85 1.49 4 1.49 2.61 3.65 4.57 0.46 0.29 292.89 1.60 5 1.86 3.35 5.90 7.00 0.55 0.32 292.92 1.71 6 2.24 4.10 8.66 10.00 0.67 0.37 292.97 1.82 7 2.61 4.84 11.95 13.50 0.77 0.41 293.01 1.91 8 2.98 5.59 15.82 17.54 0.86 0.44 293.04 1.98 9 3.35 6.34 20.22 22.15 0.97 0.47 293.07 2.06 10 3.73 7.08 25.15 27.30 1.08 0.51 293.11 2.13 11 3.54 7.27 30.05 32.41 1.18 0.54 293.14 2.20 12 3.35 6.89 34.40 36.94 1.27 0.56 293.16 2.25 13 3.17 6.52 38.24 40.93 1.34 0.59 293.19 2.30 14 2.98 6.15 41.57 44.39 1.41 0.60 293.20 2.33 15 2.80 5.78 44.41 47.34 1.47 0.62 293.22 2.36 16 2.61 5.40 46.79 49.81 1.51 0.63 293.23 2.39 17 2.42 5.03 48.72 51.82 1.55 0.64 293.24 2.41 18 2.24 4.66 50.21 53.38 1.58 0.65 293.25 2.42 19 2.05 4.29 51.30 54.50 1.60 0.66 293.26 2.43 20 1.86 3.91 51.98 55.21 1.62 0.66 293.26 2.44 21 1.68 3.54 52.28 55.52 1.62 0.66 293.26 2.44 22 1.49 3.17 52.20 55.44 1.62 0.66 293.26 2.44 23 1.30 2.80 51.78 55.00 ~ .61 0.66 293.26 2.44 24 1.12 2.42 51.01 54.20 1.60 0.66 293.26 2.43 25 0.93 2.05 49.91 53.06 ~.57 0.65 293.25 2.42 26 0.75 1.68 48.49 51.58 1.55 0.64 293.24 2.41 27 0.56 1.30 46.77 49.79 1.51 0.63 293.23 2.39 28 0.37 0.93 44.76 47.70 1.47 0.62 293.22 2.37 29 0.19 0.56 42.46 45.31 1.43 0.61 293.21 2.34 30 0.00 0.19 39.89 42.64 1.38 0.60 293.20 2.31 25 - lnflow/Outtlow Simulation 100-Year Storm Event 4 .00 3 .50 3 .00 2 .50 Y2 .00 l .50 l.00 0 .50 0.00 0 5 -----Pre- Davalopm ant Hydrogra p h I I I I I I I I I I I I I I ' ' ... ' ' ' 10 ' ' ' 15 ' ' " ' ' 20 Time (Minutes) Post- Developm ent Outflow Hydrogra ph Without Detention -----Post- Developm ent Outflow With Detention 26 25 30 Post- Davalopm ant 'Frae- Flow' Inflow/Outflow Simulation 2-Year Storm Event 1.20 1.00 0 .80 Y0.60 0 .40 0.20 0 .00 0 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hydrograph ----Total Post -Development Hydrograph 27 - Inflow/Outflow Simulation 5-Year Storm Event 1.40 1.20 l.00 0 .80 y 0.60 0.40 0 .20 0.00 0 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hydro graph ----Tota l Post-Development Hydrograph 28 - Inflow/Outflow Simulation 10-Year Storm Event 1.60 1.40 l.20 l.00 Y0.80 0 .60 0.40 0 .20 0.00 0 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hydrograph ----Total Post-Development Hydrograph 29 Inflow /Outflow Simulation 25-Year Storm Event 1.80 1.60 1.40 1.20 1.00 y 0 .80 0 .60 0 .40 0.20 0.00 0 5 10 15 20 25 30 Time (Minutes) ----Pre -Development Hydrograph ----Tota l Post-Develop ment Hydrograph 30 - Inflow/Outflow Simulation 50-Year Storm Event 2 .00 l .80 1.60 l.40 l .20 y l.00 0.80 0.60 0 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hydrograph Tota l Post-Develo pment Hydrograph 31 - Inflow/Outflow Simulation 100-Year Storm Event 2.00 1.80 1.60 0 .80 0.60 0.40 0.20 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% 60% y 50% 40% 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 Storm Depth 0.49 0.54 0.57 0.61 Storm Elevation 293.09 293 .14 293.17 293.21 293 .25 293.26 Storm Volume 725 920 1110 1322 1538 1619 Maximum Capacity 1654 1654 1654 1654 1654 1654 Percent of Capacity 44% 56% 67% 80% 93% 98% 33 Review Date:_=~.L.,/_1 b-C~1.;.....<;>.:;.._ __ _ Reviewer: ___________ _ Drainage Reports Location J¥.. Primary drainage system identified 'yf, Surrounding developments shown 'y{ Local &trccts, drainage systems shown Description l Aacageofproject JZ: Land cover described t Primary/secondary systems within property shown Cj Geocral description Drainage Basins ft Rcfcrcnccs to FIRMs if applicable ~ Secondary system fiow patterns and impact of development on existing system lf Proposed pathways to Primary system shown or described Design Criteria Po 0 Any deviation from standards being requested? 0 Discussion of site constraints and capacities (streets, existing structures, etc.) ft Discussion of any applicable previous drainage studies and how this plan will affect it Hydrologic Criteria .£ Rainfall/runoff calculation method described and calculations provided i Detention discharge I storage calculation method I calculations Ji: Storm rccurreocc intervals used P"' Discussion of other drainage facility design criteria used if not referenced in Standards Hydaulic Criteria ~ Identify capacity of systems used pf Specify velocities at critical points in system p Identify detention I retention outlet and routing ~ Discussion of other drainage facility design criteria used not referenced in Standards Drainage Facility Dgign J3 Dia:uss drainage pattcrna /flows (pre Vi. post) /)u 0 Aie they draining water onto another property owner? • if so, is it where the water flowed before? and is it not more than what flowed there before? and no faster than it flowed before? · ' Discuss erosion control measures employed t JZ1 Discuss detention pond design (sideslope, low flow channels, outlet works, freeboard, emergency spillway) N ~ 0 Discuss maintenance access and responsibilities , \ Conclusions N () 0 Verify compliance with DPDS (signed and sealed certification) p Explain effectiveness of improvements with regard to controlling discharges of S -100 year storm by a) Detaining b) Accommodating runoff in existing I proposc.d easements or ROW discharging into priawy system c) Combination ofa & b 'of12 Project Name: ~~~) Review Datc:___,_kq~,____,/ /p::;._;+-· _f o/fl..-......__ Reviewer: ___________ _ Drainage Reports(cont.) Apoendices Ji. R.cfcrcnccs (all criteria and technical infonnation used) fl Hydrologic computations A Land use assumptions for adjacent property Ji_ Minor/major storm runoff at specific points % Historic/fully developed runoff specific points J5 Hydrographs at critical points Jt Hydraulic computations ...<)kO Culvert capacities (headwater and tailwater assumptions) Pit 0 Storm sewer capacities 0 Street capacities if ,4-0 Storm inlet capacities (inlet control rating) e Open channel design ~ 0 Detention area I volume capacity I outlet capacity Attached Drawings \ A Location map with drainage patterns e Floodplain map if any ~ Drainage plan with topo (existing and proposed with arrows if needed) tJ Details of outlet structures 10 al'12 Project Name: __________ _ Review Date: __________ _ Reviewer:. __________ ~ DEVELOPMENIPERMIT 1. Application Fee ($100) 2. Application 3. Erosion Control Plan 4. EP A/NOI (> S acres) S. Public Infrastructure Inspection Fee ($300) 6. Drainage Report 7. HOA Covenants for maintenance of detention/retention ponds 8. Easements Dedicated (separate insUument) 9. TXDOT permits Wued 10. Engineer's Fstjmates (1-4 neccswy for rough grading/clearing ....... all others neccswy for full permit) J1 a(12 DRAINAGE COMPUTATIONS for Site & Grading Plan ABC Pest Control College Station, Brazos County, Texas Prepared forOwner: ABC Pest Control 1501 F.M. 21818 Suite 306 College Station, Texas 77845 Prepar ed by.· Garrett Engineering 4444 Carter Creek Parkway -Suite 108 Bryan, Texas 77802 Telephone: ( 409) 846-2688 * Revised April 24, 1998 * - REVlEWED FOR COMPLIANCE MAY 0 11998 ci±y ~rr DRAINAGE COMPUTATIONS fora Site & Grading Plan For ABC Pest Control College, Brazos County, Texas * Revised April 24, 1998 * SUMMARY Tue project consists of a 0.63 acre tract (Lot 1, Block "B" of a replat of Shenandoah -Phase One) situated on the west side of Texas State Highway No. 6 on the southwest comer of the intersection of Texas State Highway No. 6 west frontage road and Southern Plantation Drive. The 0.63 acre tract is the intended site for commercial development (Zoned CN) housing ABC Pest Control. A proposed 5000 square foot building is proposed which will be comprised of 4000 square feet of office space and 1000 square feet of storage space. The total drainage area tributary to the project is 0.63 acres. Only 0.38 acres of the said project tract will be developed with the remaining 0 .25 acres left undisturbed. (See Exhibit "A" -Site & Grading Plan). The pre-development run-off coefficient for the 0.38 acre tract was estimated to be 0.43, while taking into account specific site improvments depicted on Exhibit "A" would result in a post-development weighted run-off coefficient of 0.84. A detention facility will be constructed within the proposed concrete drive and parking area between the proposed building and the west frontage road of Texas State Highway No. 6. 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 0.38 acres of the project (developed portion only). The run-off generated on the remaining 0.25 acres will continue to flow in it's current manner and direction. The 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 0.38 acres), the pre- development run-off coefficient (being assumed at 0.43), 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 0.43 in the pre-development condition, "I" is the storm intensity in inches per hour, and "A" is tJ1e area of tlle drainage basin in acres. Computations on page 2 are based on the tributary area of 0.38 acres, the post-development run-off coefficient of 0 .84 (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 U1e same minimum time of concentration of 10 minutes). The Rational Method was again utilized to compute tlle estimated peak post-development discharge rates. The equation that represents the Rational MetJ1od 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 assumed to be 0.84.) "I" represents the rainfall intensity in inches per hour, and similarly "A" is tlle 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 detennined 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 unmetered from the project site. Pages 3 and 4 provide infonnation 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 is all of the runoff load in this case) and metered through a 12 inch 1.00 foot) wide 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 tlle pre-and post-development conditions. Page 7 and page 8 are tabulations of the post-development hydrograph for the post-development hydrograph for "free-flow" from tl1e project site and run-off directed through the detention facility respectively. Computations on page 4 determine the actual peak post-development "inflow" rate supplied to the proposed detention facility. From Ulis "inflow" rate and Ule 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 wiU1 time to peak set equal to Ule time of concentration and the tolal time base set at 3.00 times Ule time of concentration. Please note Ulat a 30 minute tolal storm event duration was utilized exclusively tllfoughout Ulis report. Having derived Ule preliminary volume requirements arid "allowable peak" discharge rate, it is now possible to design Ule final detention facility and outlet control structure. Page 12 presents a data tabulation and a depili versus volume graph of Ule detention facility. The maximum depth of the pond was set a 0.67 feet (8 inches). (Willi tl1e top of minimum curb elevation at 293.27 ft. less flow line "out" of outlet control structure at 292.60 ft.: 293.27' -292.60' = 0.68' ). Page 13 supplies a tabulation and a rating curve for the proposed outlet control structure . A rectangular weir was chosen due to depili verses discharge ratio characteristics associated with this drainage scenario and headwater depili. An ultimate storage depth of 0.67 feet is available due to the physical geometry of Ule pond. However, even at 100-year stonn conditions, runoff will be metered through Ule detention pond and metered off site Ulrough a weir into the existing drainage ditch located along the west frontage road of State Highway No. 6. The weir widili was fixed at 12 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 Ule widili of Ule weir in feet, in tl1is case assumed to be set at 12 inches. "H'' is Ule headwater depili in feet and ranges from 0 ft. to a maximum of just over 0.67 ft. Page 14 presents a tabulation of Ule relationship between discharge from Ule detention facility and Ule dimensionless quantity 2S/t-O. Also presented is a Storage Indication Curve for Ule detention facility based on the aforementioned physical characteristics of the detention pond, storage volume, inflow hydrograph, and rating curve for Ule outlet structure. The storage indication curve as shown on page 12 is a graphical solution to tlle equation presented in Ule "Drajna2e Policy And Desi2n Standards" as follows: 2s1 (I 1 + 'i2) + (----------------01) = dt 2s2 (-----------------+ Oi) dt The following pages present simulations for 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 hydro graph 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 stonn events are presented on pages 27-32. 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 tJ1e incorporation of the detention facility in the post-development condition. Total post-development peak discharge rates from tJ1e 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 facilities. Subsequent peak post-development discharge velocities are projected to be within manageable limits. The detention facility as designed meters the 2, 5, 10, 25, 50 and 100-year storm events without over- topping t h e curb. ~ Dv~ -h tk j .-A-J.e.-s o.f ~ G" ...b /me. I Determine Total Pre-Development Peak Storm Water Discharge Rates Tributary Area ("A"): 0.38 Acres Pervious Area: 0 .36 Acres Impervious Area : 0.02 Acres Run-Off Coefficient ("Cwt"): 0 .43 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.S4 S-Year : 7 .70 10-Year: 8.92 2S-Year : 9.92 SO-Year : 11 .07 100-Year: 11 .61 Peak Discharge Rate ("Q"): 2-Year: 1.07 S-Year : 1.26 10-Year: 1.46 2S-Year: 1.62 SO-Year : 1.81 100-Year: 1.90 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 Discharge (No Detention) Tributary Area ("A"): 0.38 Acres Pervious Area: 0 .09 Acres Impervious Area: 0.29 Acres Run-Off Coefficient ("Cwt"): 0.84 Time Of Concentration ("T/c"): 1 O Minutes (Min) Hourly Intensity Rates ("I "): 2-Year: 6.54 5-Year: 7 .70 10-Year: 8 .92 25-Year: 9.92 50-Year: 11.07 100-Year: 11.61 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: 2 .09 Cubic Feet I Second 5-Year: 2.47 Cubic Feet I Second 10-Year: 2.86 Cubic Feet I Second 25-Year: 3 .18 Cubic Feet I Second 50-Year: 3 .55 Cubic Feet I Second 100-Year: 3.72 Cubic Feet I Second Comparison Of Predevelopment And Post-development Peak Discharge Rates Predevelopment Post-Development Increase 2-Year: 1.07 Ft3/sec 2 .09 Ft3/sec 1.02 Ft3/sec 5-Year: 1 .26 Ft3/sec 2.47 Ft3/sec 1 .21 Ft3/sec 10-Year: 1 .46 Ft3/sec 2.86 Ft3/sec 1 .40 Ft3/sec 25-Year: 1.62 Ft3/sec 3.18 Ft3/sec 1 .55 Ft3/sec 50-Year: 1.81 Ft3/sec 3.55 Ft3/sec 1 . 73 Ft3/sec 100-Year: 1.90 Ft3/sec 3 .72 Ft3/sec 1.82 Ft3/sec Preliminary Determination Of Detention Pond Volume 2-Year: 1.02 Ft3/sec x (30 Min. x 60 Sec. I 2 ) = 921 Cubic 5-Year: 1.21 Ft3/sec x (30 Min . x 60 Sec. I 2 ) = 1,086 Cubic 10-Year: 1.40 Ft3/sec x (30 Min. x 60 Sec . I 2 ) = 1 ,257 Cubic 25-Year: 1.55 Ft3/sec x (30 Min. x 60 Sec. I 2 ) = 1 ,399 Cubic 50-Year: 1.73 Ft3/sec x (30 Min . x 60 Sec . I 2 ) = 1 ,560 Cubic 100-Year: 1.82 Ft3/sec x (30 Min. x 60 Sec . I 2 ) = 1,636 Cubic 2 Feet Feet Feet Feet Feet Feet Determine Post-Development "Free-Flow" Peak Storm Water Discharge Tributary Area ("A"): 0.00 Acres Pervious Area : 0.00 Acres Impervious Area: 0.00 Acres Run-Off Coefficient ("Cwt"): 0.00 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 ("O"): 2-Year : 0.00 5-Year : 0.00 10-Year: 0.00 25-Year: 0.00 50-Year: 0.00 100-Year: 0.00 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 "): 0.38 Acres Pervious Area : 0.09 Acres Impervious Area : 0 .29 Acres Run-Off Coefficient ("Cwt"): 0.84 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: 2.03 5-Year: 2 .46 10-Year: 2 .76 25-Year: 3.16 50-Year: 3.57 100-Year: 3.73 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 Cub ic 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 0.11 0.13 0.15 0.16 0.18 0.19 2 0.21 0.25 0.29 0.32 0.36 0.38 3 0.32 0.38 0.44 0.49 0.54 0.57 4 0.43 0.50 0.58 0.65 0.72 0.76 5 0.53 0.63 0.73 0.81 0.91 0.95 6 0.64 0.76 0.88 0.97 1.09 1.14 7 0.75 0.88 1.02 1.14 1.27 1.33 8 0.86 1.01 1.17 1.30 1.45 1.52 9 0.96 1.13 1.31 1.46 1.63 1.71 Peak=> I 10 1.07 1.26 1.46 1.62 1.81 1.90 11 1.02 1.20 1.39 1.54 1.72 1.80 12 0.96 1.13 1.31 1.46 1.63 1.71 13 0.91 1.07 1.24 1.38 1.54 1.61 14 0.86 1.01 1.17 1.30 1.45 1.52 15 0.80 0.95 1.09 1.22 1.36 1.42 16 0.75 0.88 1.02 1.14 1.27 1.33 17 0.70 0.82 0.95 1.06 1.18 1.23 18 0.64 0.76 0.88 0.97 1.09 1.14 19 0.59 0.69 0.80 0.89 1.00 1.04 20 0.53 0.63 0.73 0.81 0.91 0.95 21 0.48 0.57 0.66 0.73 0.82 0.85 22 0.43 0.50 0.58 0.65 0.72 0.76 23 0.37 0.44 0.51 0.57 0.63 0.66 24 0.32 0.38 0.44 0.49 0.54 0.57 25 0.27 0.32 0.36 0.41 0.45 0.47 26 0.21 0.25 0.29 0.32 0.36 0.38 27 0.16 0.19 0.22 0.24 0.27 0.28 28 0.11 0.13 0.15 0.16 0.18 0.19 29 0.05 0.06 0.07 0.08 0.09 0.09 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 0.21 0.25 0.29 0.32 0.35 0.37 2 0.42 0.49 0.57 0.64 0.71 0.74 3 0.63 0.74 0.86 0.95 1.06 1.11 4 0.84 0.99 1.14 1.27 1.42 1.49 5 1.05 1.23 1.43 1.59 1.77 1.86 6 1.26 1.48 1.71 1.91 2.13 2.23 7 1.47 1.73 2.00 2.22 2.48 2.60 8 1.67 1.97 2.28 2.54 2.84 2.97 9 1.88 2.22 2.57 2.86 3.19 3.34 Peak=> [ 10 2.09 2.47 2.86 3.18 3.55 3.72 11 1.99 2.34 2.71 3.02 3.37 3.53 12 1.88 2.22 2.57 2.86 3.19 3.34 13 1.78 2.10 2.43 2.70 3.01 3.16 14 1.67 1.97 2.28 2.54 2.84 2.97 15 1.57 1.85 2.14 2.38 2.66 2.79 16 1.47 1.73 2.00 2.22 2.48 2.60 17 1.36 1.60 1.86 2.07 2.30 2.42 18 1.26 1.48 1.71 1.91 2.13 2.23 19 1.15 1.36 1.57 1.75 1.95 2.04 20 1.05 1.23 1.43 1.59 1.77 1.86 21 0.94 1.11 1.29 1.43 1.60 1.67 22 0.84 0.99 1.14 1.27 1.42 1.49 23 0.73 0.86 1.00 1.11 1.24 1.30 24 0.63 0.74 0.86 0.95 1.06 1.11 25 0.52 0.62 0.71 0.79 0.89 0.93 26 0.42 0.49 0.57 0.64 0.71 0.74 27 0.31 0.37 0.43 0.48 0.53 0.56 28 0.21 0.25 0.29 0.32 0.35 0.37 29 0.10 0.12 0.14 0.16 0.18 0.19 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 0.00 0.00 0.00 0.00 0.00 0.00 2 0.00 0.00 0.00 0.00 0.00 0.00 3 0.00 0.00 0.00 0.00 0.00 0.00 4 0.00 0.00 0.00 0.00 0.00 0.00 5 0.00 0.00 0.00 0.00 0.00 0.00 6 0.00 0.00 0.00 0.00 0.00 0.00 7 0.00 0.00 0.00 0.00 0.00 0.00 8 0.00 0.00 0.00 0.00 0.00 0.00 9 0.00 0.00 0.00 0.00 0.00 0.00 Peak=> I 10 0.00 0.00 0.00 0.00 0.00 0.00 11 0.00 0.00 0.00 0.00 0.00 0.00 12 0.00 0.00 0.00 0.00 0.00 0.00 13 0.00 0.00 0.00 0.00 0.00 0.00 14 0.00 0.00 0.00 0.00 0.00 0.00 15 0.00 0.00 0.00 0.00 0.00 0.00 16 0.00 0.00 0.00 0.00 0.00 0.00 17 0.00 0.00 0.00 0.00 0.00 0.00 18 0.00 0.00 0.00 0.00 0.00 0.00 19 0.00 0.00 0.00 0.00 0.00 0.00 20 0.00 0.00 0.00 0.00 0.00 0.00 21 0.00 0.00 0.00 0.00 0.00 0.00 22 0.00 0.00 0.00 0.00 0.00 0.00 23 0.00 0.00 0.00 0.00 0.00 0.00 24 0.00 0.00 0.00 0.00 0.00 0.00 25 0.00 0.00 0.00 0.00 0.00 0.00 26 0.00 0.00 0.00 0.00 0.00 0.00 27 0.00 0.00 0.00 0.00 0.00 0.00 28 0.00 0.00 0.00 0.00 0.00 0.00 29 0.00 0.00 0.00 0.00 0.00 0.00 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 0.20 0.25 0.28 0.32 0.36 0.37 2 0.41 0.49 0.55 0.63 0.71 0.75 3 0.61 0.74 0.83 0.95 1.07 1.12 4 0.81 0.99 1.11 1.26 1.43 1.49 5 1.01 1.23 1.38 1.58 1.78 1.86 6 1.22 1.48 1.66 1.89 2.14 2.24 7 1.42 1.72 1.94 2.21 2.50 2.61 8 1.62 1.97 2.21 2.53 2.86 2.98 9 1.82 2.22 2.49 2.84 3.21 3.35 Peak=> r: 10 2.03 2.46 2.76 3.16 3.57 3.73 11 1.92 2.34 2.63 3.00 3.39 3.54 12 1.82 2.22 2.49 2.84 3.21 3.35 13 1.72 2.09 2.35 2.68 3.03 3.17 14 1.62 1.97 2.21 2.53 2.86 2.98 15 1.52 1.85 2.07 2.37 2.68 2.80 16 1.42 1.72 1.94 2.21 2.50 2.61 17 1.32 1.60 1.80 2.05 2.32 2.42 18 1.22 1.48 1.66 1.89 2.14 2.24 19 1.11 1.35 1.52 1.74 1.96 2.05 20 1.01 1.23 1.38 1.58 1.78 1.86 21 0.91 1.11 1.24 1.42 1.61 1.68 22 0.81 0.99 1.11 1.26 1.43 1.49 23 0.71 0.86 0.97 1.11 1.25 1.30 24 0.61 0.74 0.83 0.95 1.07 1.12 25 0.51 0.62 0.69 0.79 0.89 0.93 26 0.41 0.49 0.55 0.63 0.71 0.75 27 0.30 0.37 0.41 0.47 0.54 0.56 28 0.20 0.25 0.28 0.32 0.36 0.37 29 0.10 0.12 0.14 0.16 0.18 0.19 30 0.00 0.00 0.00 0.00 0.00 0.00 8 ' y y 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 Post -Development Hydrograph Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 5-Year Storm Event O .OO-tr--------+--------+-------+------~1--------+-----~ 0 5 10 15 20 25 Time (Minutes) Pre-Development Hydrograph 9 ----Post-Development Outflow Hydrograph Without Detention 30 y Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 10-Year Storm Event 0.00~----+-----+-----t----t-----+---_,;;:~ 0 5 10 15 20 25 Time (Minutes) ----Pre-Develop ment Hydrograph ----Post-Development Outflow Hyd rograph Wi thout Detent ion Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 25-Year Storm Event 30 3 .50 ----~----~---~----~---~---~ 3.00 1>------+---___,.+-'.....,....---+----+-----+-----i 2.50 1>------+--..,._-+-----"'-..:-t-----+-----+-----i 2.00 1>------+~.._--+-----+--..,..---+-----+-----i l.50 1>-------1+------;'-+-"""""";;::,----+----+""o..------+-----i l.00 1>-----,~-+---7"'"----+-----+----""'-.....::--+---..,,...,-+-----i 0 .50 1>--__,_--,,.."'---t--------1f-----+-----t-----""'-~f--~-----I o .oo~----+-----+-----+-----+----""""""--....;;;a11 0 5 10 15 20 25 Time (Minutes) ----Pr e-Development Hydrograph 10 ----Post-Development Outflow Hyd rograph Wi th o ut Detention 30 Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 50-Year Storm Event 4.00 ------..-----.--------..----.--------..--------, 3.50 +-------+------:~-----+----+------+-----; 3.00 ._-----+----J"---l------3---+----+------+---~ 2.50 ._-----+--F---+------+~---+------+---~ v2 .oo +-----+~---+-----+-----3....,._+-----+-------1 1.50 +------,~----7"-"--+----=........,-+----+-~:----+-------1 1.00 .__-J.~--+,.,£----+--------l-----=-,...+---___..3....+---~ 0.50 ._~_..,,,.."------l-----+--------l-----+-----=......i,.--3',.,..---~ 0.00 ..,:;..---....... ----+----....... ----+----....... ---~ 0 4.00 3.50 3.00 2.50 Y2 .00 1.50 1.00 0.50 0 .00 0 5 10 15 20 25 Time (Minutes) Pre-D evelopment Hydrograph Post-Develo pment Outflow Hydrograph Without Detention Total Pre-Development Vs. Total Post-Development (No Detention) Peak Discharge Rates 100-Year Storm Event 5 10 15 20 25 Time (Minutes) Pre-De velopment Hydrograph 11 ----Post-Development Outflow Hydrograph Without Detention 30 30 begin ca Detention Pond Depth Vs. Volume Elevation Depth Volume {Feet} {Ft3} 2-year 5-year 292 .60 0 .00 0 10-year 292 .73 0.13 10 25-year 292.86 0 .26 78 50-year 292 .99 0.39 325 100-yea 293 .12 0 .52 847 293 .27 0 .67 1 ,654 Detention Pond Depth Vs. Volume 0.70 y v ~ / v __..... ~v ~/ v v 0 .60 0 .50 0 .40 j ( 0.30 0 .20 0.10 0.00 0 200 400 600 800 1 ,000 1 ,200 1,400 1 ,600 1,800 Detention Pond Volume (Cubic Feet) 12 Rating Curve For Outlet Control Structure Weir Length(L): 1.00 De th Vs. Volume Elevation Depth Discharge (Feet) Ft3/Sec 292.60 0.00 0 .0 0 292.73 0.13 0 .14 292 .86 0.26 0.40 292 .99 0 .39 0.73 293.12 0.52 1.12 293.27 0.67 1.65 Rating Curve For Outlet Control Structure Depth Vs. Volume 0 .70 y / "' / / v , ~ / v / v I v I 0 .60 0 .50 0 .40 0 .30 0 .20 0 .10 0.00 0 .00 0 .2 0 0 .40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 Discharge (Cubic Feet Per Second) 13 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 0.13 10 0.14 0.33 0.47 0.26 78 0.40 2 .60 3 .00 0.39 325 0.73 10 .83 11 .56 0 .52 847 1.12 28.23 29 .36 0 .67 1,654 1.65 55 .13 56 .78 Storage Indication Curve 1.80 1.60 1.00 y 0 .80 0 .60 0 .40 0 .00 0 .00 10.00 20 .00 30 .00 40.00 50 .00 60.00 2s/t+O (Cubic Feet Per Second) 14 Inflow I Outflow Simulation 2-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 0.00 292.60 0.00 1 0.20 0.20 0.08 0.20 0.06 0.07 292.67 0.81 2 0.41 0.61 0.36 0.69 0.16 0.14 292.74 1.14 3 0.61 1.01 0.91 1.38 0.23 0.18 292.78 1.28 4 0.81 1.42 1.67 2.33 0.33 0.23 292.83 1.44 5 1.01 1.82 2.66 3.49 0.42 0.27 292.87 1.55 6 1.22 2.23 3.95 4.89 0.47 0.29 292.89 1.62 7 1.42 2.63 5.51 6.58 0.54 0.32 292.92 1.69 8 1.62 3.04 7.32 8.54 0.61 0.35 292.95 1.77 9 1.82 3.44 9.36 10.76 0.70 0.38 292.98 1.85 10 2.03 3.85 11.68 13.21 0.77 0.40 293.00 1.90 11 1.92 3.95 13.99 15.63 0.82 0.42 293.02 1.95 12 1.82 3.75 16.00 17.73 0.87 0.44 293.04 1.98 13 1.72 3.55 17.73 19.54 0.91 0.45 293.05 2.01 14 1.62 3.34 19.19 21.07 0.94 0.46 293.06 2.04 15 1.52 3.14 20.39 22.33 0.97 0.47 293.07 2.06 16 1.42 2.94 21.34 23.33 0.99 0.48 293.08 2.07 17 1.32 2.73 22.06 24.08 1.01 0.48 293.08 2.09 18 1.22 2.53 22.56 24.60 1.02 0.49 293.09 2.09 19 1.11 2.33 22.84 24.89 1.03 0.49 293.09 2.10 20 1.01 2.13 22.91 24.96 1.03 0.49 293.09 2.10 21 0.91 1.92 22.78 24.83 1.02 0.49 293.09 2.10 22 0.81 1.72 22.47 24.50 1.02 0.49 293.09 2.09 23 0.71 1.52 21.98 23.99 1.01 0.48 293.08 2.08 24 0.61 1.32 21.31 23.29 0.99 0.48 293.08 2.07 25 0.51 1.11 20.48 22.43 0.97 0.47 293.07 2.06 26 0.41 0.91 19.50 21.40 0.95 0.46 293.06 2.04 27 0.30 0.71 18.36 20.21 0.92 0.46 293.06 2.02 28 0.20 0.51 17.08 18.87 0.89 0.45 293.05 2.00 29 0.10 0.30 15.67 17.39 0.86 0.43 293.03 1.98 30 0.00 0.10 14.12 15.77 0.82 0.42 293.02 1.95 15 - 2 .50 2 .00 1.50 y 1.00 0.50 0 .00 0 Inflow/Outflow Simulation 2-Year Storm Event I I I 5 Pre-- Developm ant Hydrogra ph I I I - I I I • I -- I '\. ... .... .... .... .... 10 15 20 25 30 Time (Minutes) -Post-Post-- - - - - - -Post- Developm Develo pm Developm ent ent ent "F ree- Outflow Outflow Flow" Hydrogra With ph Detention Without Detention 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) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 292.60 0.00 1 0.25 0.25 0.10 0.25 0.07 0.08 292.68 0.87 2 0.49 0.74 0.48 0.84 0.18 0.15 292.75 1.17 3 0.74 1.23 1.18 1.72 0.27 0.20 292.80 1.34 4 0.99 1.72 2.13 2.91 0.39 0.26 292.86 1.52 5 1.23 2.22 3.45 4.35 0.45 0.28 292.88 1.59 6 1.48 2.71 5.11 6.15 0.52 0.31 292.91 1.67 7 1.72 3.20 7.11 8.32 0.60 0.34 292.94 1.76 8 1.97 3.69 9.40 10.80 0.70 0.38 292.98 1.85 9 2.22 4.19 12.04 13.59 0.78 0.41 293.01 1.91 10 2.46 4.68 15.03 16.72 0.84 0.43 293.03 1.97 11 2.34 4.80 18.00 19.83 0.91 0.45 293.05 2.02 12 2.22 4.56 20.61 22.56 0.97 0.47 293.07 2.06 13 2.09 4.31 22.87 24.92 1.03 0.49 293.09 2.10 14 1.97 4.06 24.79 26.93 1.07 0.50 293.10 2.13 15 1.85 3.82 26.39 28.61 1.11 0.51 293.11 2.15 16 1.72 3.57 27.69 29.96 1.14 0.52 293.12 2.17 17 1.60 3.33 28.70 31.02 1.16 0.53 293.13 2.18 18 1.48 3.08 29.44 31.78 1.17 0.53 293.13 2.19 19 1.35 2.83 29.91 32.27 1.18 0.54 293.14 2.20 20 1.23 2.59 30.13 32.50 1.18 0.54 293.14 2.20 21 1.11 2.34 30.10 32.47 1.18 0.54 293.14 2.20 22 0.99 2.09 29.84 32.20 1.18 0.54 293.14 2.20 23 0.86 1.85 29.35 31.69 1.17 0.53 293.13 2.19 24 0.74 1.60 28.64 30.95 1.16 0.53 293.13 2.18 25 0.62 1.35 27.72 29.99 1.14 0.52 293.12 2.17 26 0.49 1.11 26.60 28.83 1.11 0.52 293.12 2.16 27 0.37 0.86 25.30 27.46 1.08 0.51 293.11 2.14 28 0.25 0.62 23.82 25.91 1.05 0.50 293.10 2.11 29 0.12 0.37 22.16 24.19 1.01 0.48 293.08 2.09 30 0.00 0.12 20.35 22.29 0.97 0.47 293.07 2.06 17 ~ y Inflow/Outflow Simulation 5-Year Storm Event 2 .50 2.00 1.50 I 1.00 0.50 0.00 0 5 -----Pre - Developm ent Hydrogra ph I I I • I I I I I I I I I I ' ' 10 ' ' ' ' ' ' 15 ' ' ' ' ' ' ' ' 20 Time (Minutes) Post- Devel opm ent Outflow Hydrogra ph Without Detention -----Post - Developm ent Outflow With Detention 18 25 30 Post- Developm e 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 0.00 292.60 0.00 1 0.28 0.28 0.11 0.28 0.08 0.09 292.69 0.90 2 0.55 0.83 0.57 0.94 0.19 0.16 292.76 1.19 3 0.83 1.38 1.37 1.95 0.29 0.21 292.81 1.38 4 1.11 1.94 2.48 3.30 0.41 0.27 292.87 1.54 5 1.38 2.49 4.02 4.97 0.47 0.29 292.89 1.62 6 1.66 3.04 5.95 7.06 0.56 0.32 292.92 1.71 7 1.94 3.59 8.24 9.55 0.65 0.36 292.96 1.80 8 2.21 4.15 10.89 12.39 0.75 0.40 293.00 1.89 9 2.49 4.70 13.95 15.59 0.82 0.42 293.02 1.95 10 2.76 5.25 17.40 19.20 0.90 0.45 293.05 2.01 11 2.63 5.39 20.84 22.80 0.98 0.47 293.07 2.07 12 2.49 5.11 23.85 25.95 1.05 0.50 293.10 2.11 13 2.35 4.84 26.47 28.69 1.11 0.52 293.12 2.15 14 2.21 4.56 28.72 31.03 1.16 0.53 293.13 2.18 15 2.07 4.29 30.62 33.00 1.19 0.54 293.14 2.21 16 1.94 4.01 32.18 34.63 1.22 0.55 293.15 2.23 17 1.80 3.73 33.41 35.91 1.25 0.56 293.16 2.24 18 1.66 3.46 34.33 36.87 1.27 0.56 293.16 2.25 19 1.52 3.18 34.95 37.51 1.28 0.57 293.17 2.26 20 1.38 2.90 35.28 37.85 1.29 0.57 293.17 2.26 21 1.24 2.63 35.33 37.91 1.29 0.57 293.17 2.26 22 1.11 2.35 35.12 37.68 1.28 0.57 293.17 2.26 23 0.97 2.07 34.64 37.19 1.27 0.56 293.16 2.25 24 0.83 1.80 33.92 36.44 1.26 0.56 293.16 2.25 25 0.69 1.52 32.96 35.44 1.24 0.56 293.16 2.23 26 0.55 1.24 31.77 34.21 1.22 0.55 293.15 2.22 27 0.41 0.97 30.36 32.74 1.19 0.54 293.14 2.20 28 0.28 0.69 28.74 31.05 1.16 0.53 293.13 2.18 29 0.14 0.41 26.91 29.15 1.12 0.52 293.12 2.16 30 0.00 0.14 24.90 27.05 1.07 0.50 293.10 2.13 19 - 3 .00 2.50 2 .00 y 1.50 1.00 0.50 0.00 0 Inflow/Outflow Simulation 10-Year Storm Event 5 Pre - Develop ment Hydro gr a ph I I I . I I I . I I I . I I I I . I ... I ... ... ... ... ... ... ... ... ... 10 15 20 25 Time (Minutes) . Post-Post---------- De ve lop Develop ment ment Outflow Outflow Hydrogra With ph Detention With out Det e ntio n 20 30 Post- Deve lop ment '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 0.00 292.60 0.00 0.32 0.32 0.13 0.32 0.09 0.10 292.70 0.94 2 0.63 0.95 0.67 1.08 0.20 0.17 292.77 1.22 3 0.95 1.58 1.61 2.25 0.32 0.23 292.83 1.43 4 1.26 2.21 2.96 3.82 0.43 0.27 292.87 1.57 5 1.58 2.84 4.79 5.80 0.51 0.31 292.91 1.66 6 1.89 3.47 7.06 8.26 0.60 0.34 292.94 1.76 7 2.21 4.10 9.73 11.16 0.72 0.38 292.98 1.86 8 2.53 4.74 12.88 14.47 0.79 0.41 293.01 1.93 9 2.84 5.37 16.49 18.25 0.88 0.44 293.04 1.99 10 3.16 6.00 20.54 22.49 0.97 0.47 293.07 2.06 11 3.00 6.16 24.57 26.70 1.07 0.50 293.10 2.12 12 2.84 5.84 28.12 30.41 1.14 0.53 293.13 2.18 13 2.68 5.53 31.23 33.65 1.21 0.54 293.14 2.21 14 2.53 5.21 33.92 36.44 1.26 0.56 293.16 2.25 15 2.37 4.89 36.21 38.82 1.30 0.57 293.17 2.27 16 2.21 4.58 38.10 40.79 1.34 0.58 293.18 2.29 17 2.05 4.26 39.62 42.37 1.37 0.59 293.19 2.31 18 1.89 3.95 40.78 43.57 1.39 0.60 293.20 2.32 19 1.74 3.63 41.59 44.41 1.41 0.60 293.20 2.33 20 1.58 3.32 42.07 44.91 1.42 0.61 293.21 2.34 21 1.42 3.00 42.22 45.07 1.42 0.61 293.21 2.34 22 1.26 2.68 42.07 44.90 1.42 0.61 293.21 2.34 23 1.11 2.37 41.61 44.43 1.41 0.60 293.20 2.33 24 0.95 2.05 40.87 43.66 1.40 0.60 293.20 2.32 25 0.79 1.74 39.86 42.61 1.38 0.59 293.19 2.31 26 0.63 1.42 38.57 41.28 1.35 0.59 293.19 2.30 27 0.47 1.11 37.04 39.68 1.32 0.58 293.18 2.28 28 0.32 0.79 35.26 37.83 1.29 0.57 293.17 2.26 29 0.16 0.47 33.24 35.73 1.25 0.56 293.16 2.24 30 0.00 0.16 30.99 33.40 1.20 0.54 293.14 2.21 21 - Inflow/Outflow Simulation 25-Year Storm Event 3.50 3.00 2.50 2.00 y 1.50 1.00 0.50 0 .00 0 5 -----Pre- Developm ent Hydr ogra ph I I I I I I I I I I " I " " 10 " " " " " " " " 15 " " " " " 20 Time (Minutes) Post- Deve lopm ent Outflow Hyd rogra ph Without Detention ----•Post- De ve lopm ent Outflow With Detention 22 25 30 Post- Devel o pm ent "F ree- 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) (FVSec) 0 0.00 0.00 0.00 0.00 0.00 0.00 292.60 0.00 1 0.36 0.36 0.15 0.36 0.11 0.11 292.71 0.98 2 0.71 1.07 0.78 1.22 0.22 0.17 292.77 1.25 3 1.07 1.78 1.86 2.57 0.35 0.24 292.84 1.47 4 1.43 2.50 3.46 4.36 0.45 0.28 292.88 1.59 5 1.78 3.21 5.59 6.67 0.54 0.32 292.92 1.69 6 2.14 3.93 8.21 9.52 0.65 0.36 292.96 1.80 7 2.50 4.64 11.34 12.85 0.76 0.40 293.00 1.90 8 2.86 5.35 15.00 16.69 0.84 0.43 293.03 1.97 9 3.21 6.07 19.19 21.07 0.94 0.46 293.06 2.04 10 3.57 6.78 23.87 25.97 1.05 0.50 293.10 2.11 11 3.39 6.96 28.52 30.83 1.15 0.53 293.13 2.18 12 3.21 6.60 32.66 35.13 1.23 0.55 293.15 2.23 13 3.03 6.25 36.29 38.91 1.31 0.57 293.17 2.27 14 2.86 5.89 39.45 42.18 1.37 0.59 293.19 2.31 15 2.68 5.53 42.14 44.98 1.42 0.61 293.21 2.34 16 2.50 5.18 44.38 47.31 1.47 0.62 293.22 2.36 17 2.32 4.82 46.20 49.20 1.50 0.63 293.23 2.38 18 2.14 4.46 47.60 50.66 1.53 0.64 293.24 2.40 19 1.96 4.10 48.61 51.71 1.55 0.64 293.24 2.41 20 1.78 3.75 49.23 52.35 1.56 0.65 293.25 2.41 21 1.61 3.39 49.49 52.62 1.57 0.65 293.25 2.42 22 1.43 3.03 49.40 52.52 1.56 0.65 293.25 2.41 23 1.25 2.68 48.96 52.07 1.56 0.65 293.25 2.41 24 1.07 2.32 48.20 51.28 1.54 0.64 293.24 2.40 25 0.89 1.96 47.12 50.16 1.52 0.64 293.24 2.39 26 0.71 1.61 45.74 48.73 1.49 0.63 293.23 2.38 27 0.54 1.25 44.07 46.99 1.46 0.62 293.22 2.36 28 0.36 0.89 42.12 44.97 1.42 0.61 293.21 2.34 29 0.18 0.54 39.91 42.66 1.38 0.60 293.20 2.31 30 0.00 0.18 37.43 40.08 1.33 0.58 293.18 2.29 23 l"l Inflow/Outflow Simulation 50-Year Storm Event 4.00 3.50 3.00 2.50 Y2.00 I 1.50 1.00 0.50 0.00 0 5 -----Pre- Developm ent Hydr ogra ph I I I I I I I I I I I I I " I " " ' 10 15 " ' 20 Time (Minutes) Post- Developm ent Outflow Hydrogra ph Without Detention -----Post- Developm ent Outflow With Detention 24 25 30 Post- De velop m ent 'F ree- Flow' Inflow I Outflow Simulation 100-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 0.00 292.60 0.00 1 0.37 0.37 0.15 0.37 0.11 0.11 292.71 1.00 2 0.75 1.12 0.83 1.27 0.22 0.18 292.78 1.26 3 1.12 1.86 1.96 2.69 0.37 0.25 292.85 1.49 4 1.49 2.61 3.65 4.57 0.46 0.29 292.89 1.60 5 1.86 3.35 5.90 7.00 0.55 0.32 292.92 1.71 6 2.24 4.10 8.66 10.00 0.67 0.37 292.97 1.82 7 2.61 4.84 11.95 13.50 0.77 0.41 293.01 1.91 8 2.98 5.59 15.82 17.54 0.86 0.44 293.04 1.98 9 3.35 6.34 20.22 22.15 0.97 0.47 293.07 2.06 10 3.73 7.08 25.15 27.30 1.08 0.51 293.11 2.13 11 3.54 7.27 30.05 32.41 1.18 0.54 293.14 2.20 12 3.35 6.89 34.40 36.94 1.27 0.56 293.16 2.25 13 3.17 6.52 38.24 40.93 1.34 0.59 293.19 2.30 14 2.98 6.15 41.57 44.39 1.41 0.60 293.20 2.33 15 2.80 5.78 44.41 47.34 1.47 0.62 293.22 2.36 16 2.61 5.40 46.79 49.81 1.51 0.63 293.23 2.39 17 2.42 5.03 48.72 51.82 1.55 0.64 293.24 2.41 18 2.24 4.66 50.21 53.38 1.58 0.65 293.25 2.42 19 2.05 4.29 51.30 54.50 1.60 0.66 293.26 2.43 20 1.86 3.91 51.98 55.21 1.62 0.66 293.26 2.44 21 1.68 3.54 52.28 55.52 1.62 0.66 293.26 2.44 22 1.49 3.17 52.20 55.44 1.62 0.66 293.26 2.44 23 1.30 2.80 51.78 55.00 1.61 0.66 293.26 2.44 24 1.12 2.42 51.01 54.20 1.60 0.66 293.26 2.43 25 0.93 2.05 49.91 53.06 1.57 0.65 293.25 2.42 26 0.75 1.68 48.49 51.58 1.55 0.64 293.24 2.41 27 0.56 1.30 46.77 49.79 1.51 0.63 293.23 2.39 28 0.37 0.93 44.76 47.70 1.47 0.62 293.22 2.37 29 0.19 0.56 42.46 45.31 1.43 0.61 293.21 2.34 30 0.00 0.19 39.89 42.64 1.38 0.60 293.20 2.31 25 ~ Inflow/Outflow Simulation 100-Year Storm Event 4.00 3.50 3.00 2.50 Y2.00 1.50 1.00 0.50 0.00 0 5 -----Pre- Developm ent Hydrogra ph I I I I I I I I I I I I I I ' ' ' ' ' ' 10 15 ' ' ' ' ' ' ' 20 Time (Minutes) Post- De v elopm ent Outfl ow Hydrogra ph With out Det e nti o n -----Post- Develop m e nt Outfl ow Wit h Det ention 26 25 30 Post - Develo pm ent "Fr ee- Fl ow· Inflow/Outflow Simulation 2-Year Storm Event 1.20 1.00 0.80 Y0.60 0.40 0 .20 0 .00 0 5 10 15 20 25 30 Time (Minutes) ----Pre-Development Hydrograph ----Total Post-Development Hydrograph 27 Inflow/Outflow Simulation 5-Year Storm Event 1.40 1.20 1.00 0 .80 y 0 .60 0.40 0.20 0.00 0 5 10 15 20 25 30 Time (Minutes) ----Pre -Development Hydrograph ----Tota l Post -D evelo pment Hyd ro g raph 28 Inflow/Outflow Simulation 10-Year Storm Event 1.60 1.40 1.20 1.00 Y0.80 0.60 0.40 0.20 0.00 0 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Total Post-Development Hydrograph 29 - Inflow/Outflow Simulation 25-Year Storm Event y 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 2 .00 1.80 1.60 1.40 1.20 y 1.00 0.80 0 .60 0.40 0 .20 0 .00 0 5 10 15 20 25 30 Time (Minutes) ----Pre -D evelopment Hydrograph ----Total Post-Develop m ent Hydrograph 31 Inflow/Outflow Simulation 100-Year Storm Event 0 5 10 15 20 25 30 Time (Minutes) Pre-Development Hydrograph ----Total Post-Development Hydrograph 32 Detention Pond Storage Volumes as Percent of Maximum Volume 100% 90% 80% 70% 60% y 50% 40% 30% 20% 10% 0% 2-year 5-year 10-year 25-year SO-year 100-year Design Storm Storm Depth Storm Elevation 293.09 293 .14 293 .17 293.26 Storm Volume 725 920 1110 1322 1538 1619 Maximum Capacity 1654 1654 1654 1654 1654 1654 Percent of Capacity 44% 56% 67 % 80% 93% 98% 33