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HomeMy WebLinkAboutDrainage StudyDrainage Study FOR M.D.W. CENTRE DETENTION FACILITY MODIFICATIONS at FULLY DEVELOPED CONDITIONS Wheeler Subdivision, Phase Two Lot 2, Block One College Station Brazos County, Texas October 3, 2011 J7PCE OF 7e�'�St ZjCE N 5�0..• , �I« Prepared For: M.D. Wheeler, Inc. 1919 Whitney Houston, TX 77006 Prepared By RME Consulting Engineers Texas Firm Registration No. F-004695 P.O. Box 9253 College Station, TX 77845 RME No. 197-0423 LIST Or TABLES: PAGE Section 3.0 — Hydrologic Modeling Table 91: To — Overland Sheet Flow..................................................................................................................... 7 Table 92: T,z — Shallow and/or Concentrated Flow................................................................................................ 7 Table#3: Tc Summary........................................................................................................................................... 8 Table #4: Drainage Basin Runoff Quantities......................................................................................................... 9 Section 4.0 — Detention Facility Routin Table #5: Detention Facility Tailwater................................................................................................................. 12 Table #6: Straight Line Tailwater Estimations..................................................................................................... 12 Table #7: Detention Facility Routing................................................................................................................... 13 Section 5.0 — Storm Drainage System Table#8: Storm Drainage Summary.................................................................................................................... 15 197-0423 Drainage Report Page - ii ATTACHMENTS: Section 1.0 — General Information C1.1 - Overall Site Plan Vicinity Map FIRM Panel Map LOMR Update Map Section 2.0 — Watersheds & Drainage Areas Burton Creek Watershed Area Existing Conditions Drainage Area Map Proposed Conditions Drainage Area Map Storm System Drainage Area Map Section 3.0 — Hydrologic Modeling HydroCAD — Existing & Proposed Conditions Drainage Calculations Section 4.0 — Detention Facility & Routing C1.2A: Site Grading & Drainage Plan HydroCAD — Proposed Conditions Pond Routing Calculations — Pond 1 Section 5.0 — Storm Drainage System Winstorm — Hydraulic Computations — Storm Drainage System "A" 197-0423 Drainage Report Page - iii A Drainage Study M.D.W. CENTRE — DETENTION FACILITY MODIFICATIONS at FULLY DEVELOPED CONDITIONS Wheeler Subdivision, Phase Two Lot 2, Block One College Station Brazos County, Texas 1.0 GENERAL INFORMATION 1.1 Scope of Report: This report addresses the existing conditions and proposed "future" drainage improvements for the M.D.W. Centre development which is located on Lot 2, Block One of the Wheeler Subdivision, Phase Two. It is the property owner/developer's intention to modify the existing "dry" detention facility into a landscaped water feature/amenity with a retention element to the existing pond. The original Drainage Report was prepared by this office and issued on January 23, 2006. This drainage study's scope will analyze the proposed detention facility modificationidesign methods and proposed configurations and the proposed internal storm drainage system improvements designed for the detention facility modifications. All drainage system improvements (i.e. detention facilities, storm sewer, etc...) will be designed to accommodate the anticipated existing, proposed, and ultimate development conditions. The proposed development and drainage improvements are designed and analyzed in accordance with the criteria outlined in the "Unified Stormwater Design Guidelines" (USDG) manual of the City of College Station (CoCS). 1.2 Site and General Location: The MDW Centre development is as mentioned before located on Lot 2, Block One of the Wheeler Subdivision, Phase 2 which is identified as 1150 & 1200 University Drive. This lot is a 6.07 acre tract that is zoned as C-1 (general commercial). The existing improvements generally consist of 6,475 square -foot restaurant (currently Red Lobster) and 179 parking spaces with appropriate drives, bridges over the creek, and utilities. The existing improvements currently occupy approximately 3.42 acres of land. The future development, on the remaining portion of the property, is anticipated to include a 40,000 square -foot (3-story) hotel structure along with all necessary associated improvements of paving, drainage, and utilities. The existing conditions of the property are more fully illustrated on the C 1.1 - Overall Site Plan which is provided in the "Attachment — Section 1.0" portion of this report. 197-0423 Drainage Report Page -1 M.D.W. Centre —Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 The M.D.W. Centre existing development is wholly contained on Lot 2, Block 1 of the Wheeler Subdivision, Phase Two. The property is bounded by University Drive (F.M. No. 60) to the north and Lincoln Avenue along its west and south. Adjacent developments to the west and northwest consist of the Lincoln Place Garten Homes, the Lincoln Place Apartments and the Amerisuites Hotel. Access to the tract can be accomplished from the north by means of a private access drive, taking access from University Drive and through the Amerisutes Hotel, which is covered by a private joint access easement (Vol. 3490, Pg. 269). Access is also available along the properties' east and south boundaries by Lincoln Avenue. A Vicinity Man, for this project site, is provided and is located in the "Attachment — Section 1.0" portion of this manual. This map is being provided as an aid in locating the site. Drawings describing the work and its specific locations are contained in the Construction Drawings prepared by RME Consulting Engineers, College Station, Brazos County, TX. These Construction Drawings are included as part of this Drainage Report by reference. 1.3 Description of Existing Conditions and Drainage Patterns: The 6.07 acre tract of land, which contains the MDW Centre development, is a moderately well sloping (approximately 6%) substantially developed site with storm sewer systems and natural overland drainage that conveys runoff to the unnamed tributary of Burton Creek. This unnamed tributary drains in a northeasterly and bisects the property with approximately 1/3 on the north side of the tributary and the remaining 2/3's to its south. The tributary conveys runoff through a double barrel 48" RCP storm culvert, under University Drive, to Burton Creek, thence to Carters Creek, thence to the Navasota River, thence to the Brazos River and ultimately to the Gulf of Mexico. Currently the MDW Centre is approximately 71% improved with impervious or landscaped ground cover. All other areas are unimproved and in a moderately pristine condition. Existing (undisturbed) land -cover general consists of open grassy areas on the high overbanks and thick brush, weeds, and trees along the creek banks of the unnamed tributary. Elevations range on the site from approximately 279' Mean Sea Level (MSL) to approximately 303' MSL. The Brazos County soil maps, as reported on the NRCS Web Soil Survey web -based program, indicates that the studied areas are primarily comprised of Type D soils in the upland areas with scattered Type C soils within the creek and floodplain areas. These soils generally consist of clays or silty clay/sand mixtures with low to medium absorption rates. The current drainage conditions and concepts of the existing drainage structures and detention facility are as follows: 1) Detain increased impervious runoff to, or below, existing drainage conditions; 2) Currently all runoff generated for the Red Lobster portion of the development is discharged directly to the unnamed tributary on restricted and without detention; 3) The secondary drainage system, upstream of the MDW Centre, discharges into the existing detention facility by means of a 24" RCP which crossing 197-0423 Drainage Report Page -2 M.D.W. Centre — Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 under Lincoln Avenue. Runoff collected at this point is detained significantly below pre -development conditions to compensate for the undetained runoff from the Red Lobster improvements. Thus the net runoff, at the downstream limit of the property, is equal to or less than the original pre -development runoff rates; The existing "dry" detention pond currently consist of a top berm elevation of 291.00', a maximum pooling elevation of 290.44', a minimum flowline of 282.50', and with a maximum storage capacity of 52,706 cubic -feet. Runoff is restricted by 21.75" diameter orifice that is placed in the junction box of the 36" diameter discharge pipe. 1.4 FEMA Information: Portions of this site lie within the 100-year floodplain as graphically depicted by the Federal Emergency Management Agency (FEMA) — Flood Insurance Rate Map (FIRM) Communitoariel number 480083 0142C, with an effective date of July 2, 1992. A excerpt of this FIRM Panel Man is located in the "Attachment — Section 1.0" section of the Drainage Report. In 2003, a Letter of Map Revision (LOMR) was issued by FEMA which updated the 100-year floodplain and defined floodway for the unnamed tributary which traverses the subject properly. This LOMR was prepared by Longaro & Clarke, Inc. and issued by FEMA under Case No. 03-06-102P with an effective date of October 30, 2003. The LOMR Update May which graphical revised the floodplain/floodway, issued with the LOMR, is provided in the "Attachment — Section 1.0" appendix of the Drainage Study. 2.0 WATERSHEDS & DRAINAGE AREAS 2.1 Detention Facility Watersheds (Existing Conditions): As previously discussed, the subject development area is located in a watershed of an unnamed tributary that drains into the Burton Creek Watershed Area. An exhibit of this watershed is taken from the USDG manual with the MDW Centre development area identified and has been included in the "Attachment — Section 2.0" appendix of the report. Since this drainage study will include the hydrologic/hydraulic modeling of one (1) detention facility, an appropriate drainage area map called the Existing Conditions Drainage Area Map (which is located in the "Attachment — Section 2.0" portion of the Drainage Report), was developed for considerations of runoff patterns and quantities. For pre -development conditions (prior to the Red Lobster restaurant) two (2) individual drainage basins were considered, analyzed, and are as follows. These drainage areas where slightly modified to make comparable analysis of the proposed/modified detention facility improvements. Drainage Area "XI" — This drainage area consists generally of the 6.07-acre tract for pre - development or existing conditions (prior to the Red Lobster restaurant). Drainage Area "XI" will constitute 4.44 acres. Analysis of this drainage area will provide runoff characteristics for the MDW Centre site at its original undeveloped state. This runoff 197-0423 Drainage Report Page-3 M.D.W. Centre — Detention Facility Modifications Drainage Study RAM Consulting Engineers October 3, 2011 data will be the "benchmark" data for the respective post -development area analysis so that increased runoff can be measured and appropriately detained. Drainage Area "X2" — This watershed is approximately 16.16 acres containing the drainage basin of a secondary drainage system that drains into the unnamed tributary of Burton Creek. This watershed illustrates existing conditions (prior to the Red Lobster restaurant) and will yield runoff characteristics accordingly for this secondary system. Analysis of this drainage area will provide additional "benchmark" data for the respective post -development area analysis so that increased runoff can be measured and appropriately detained. NOTE: A detention facility was constructed for the Grand Oaks Subdivision which is wholly contained in Drainage Area "X2". RME requested a copy of the Drainage Report with its original study (1/23/06), from the CoCS Planning & Development Services, but no copy was one file. It is assumed that this subdivision's detention pond meters runoff at pre -development rates, during all rainfall events, which existed prior to this development. Therefore, the runoff coefficient, for the Grand Oaks Subdivision, will set set at a moderately high pre -development "C". 2.2 Detention Facility Watersheds (Proposed Conditions): For post -development conditions two (2) individual drainage basins were considered and analyzed and are as follows. The Proposed Conditions Drainage Area Map illustrates these drainage areas and is located in the "Attachment — Section 2.0" section of the Drainage Study. Drainage Area Map "Pl" — This drainage area consists of a portion of the 6.07-acre tract for post -development or proposed/ultimate conditions and constitutes 5.34 acres. Analysis of this drainage area will provide runoff characteristics for the project site at its fully "ultimate" developed state which includes the Red Lobster improvements and projected future development. This hydrologic data will illustrate the increased runoff, when compared to the runoff values of Drainage Area "Xl", due to new impervious cover, proposed grading, and landscaping. Drainage Area Map "P2" — This watershed is approximately 15.26 acres containing the drainage area of the secondary drainage system that discharges into the unnamed tributary of Burton Creek as modified by the proposed grading, sub -surface drainage structures, and detention facility. The proposed detention facility will be placed at the headworks of this drainage system. Runoff will be routed through this detention facility and metered through its outlet structure so that discharge rates are reduced so that the net change at the inlet of the existing 2-48" RCP structure (under University Drive) is equal to or less than pre -development rates. 2.3 Subdrainage Basins for Storm Sewer Collection System: For analysis of the internal storm drainage system, the proposed Drainage Area "P2" was further broken down into smaller sub -drainage areas so that individual curb inlets, grate inlets, and conveyance elements could properly be designed and analyzed. The Storm System Drainage Area Map illustrates these sub -drainage areas and is located in the "Attachment — Section 2.0" portion of this Drainage Study. 197-0423 Drainage Report Page - 4 M.D.W. Centre — Detention Facility Modifications RMG Consulting Engineers Drainage Study October 3, 2011 3.0 HYDROLOGIC MODELING 3.1 Rational Formula and Methodology: The Natural Resources Conservation Service (MRCS), formerly the Soil Conservation Service, developed the runoff curve number method as a means of estimating the amount of rainfall appearing as runoff. The SCS-TR 20 formula calculates the peak discharge and volumes in a reliable fashion for moderate sized (50 to 400 acres) watersheds. The City of College Station requires that developments with detention facilities utilize the SCS method regardless of watershed size. However, since the original drainage study (1/23/06) utilized the Rational Method this report and analysis will continue to utilize this methodology of hydrology computing, The Rational Method (Q=CIA) is one of the more frequently used methods to determine the peak runoff from a watershed and is typically reliable for small watersheds (< 50 acres). The Rational Method generates hydrologic data based on drainage area geometries, surface conditions, and rainfall intensities. The Rational Method will be employed to determine the sizes of watershed's runoff values for the sub -drainage areas, detention systems, and for the internal storm drain systems, and it is explained further as: Q = CIA where, Q = peak runoff rate (cubic feet per second); C = runoff coefficient — This represents the average runoff characteristics of the land cover within the drainage area and is a dimensionless coefficient. Runoff coefficients are interpolated from either Table C-2 or C-3 of the USDG; I = average rainfall intensity (in/hr); A = area of land that contributes stormwater runoff to the area of study (acres); 3.2 Rainfall Intensity `I". Rainfall intensities (I) are the average rate of rainfall in inches per hour for a given rainfall event. The duration of "I" is assumed to occur at the computed Time -of - Concentration for each respective drainage basin. Rainfall intensities can be determined by use of intensity -duration -frequency (IDF) curves or from intensity equations which are provided in the TxDOT Hydraulic Manual. 3.3 Weighted Runoff Coefficient "C": The runoff coefficient (C) for various sub -drainage basins was estimated from the USDG, Table C-2 and C-3 by comparison of runoff surface types to percentage of land coverage and total drainage area. The pre- and post -construction runoff coefficient "C" for the studied drainage areas were determined by calculating the weighted average of the runoff coefficient for the different surfaces types. Calculations for these coefficients are as follows: 197-0423 Drainage Report Page-5 M.D.W. Centre — Detention Facility Modifications RME Consulting Engineers Drainage Study October 3, 2011 Drainage Area "Xl" Runoff Coefficient "CWTD". 1.03 Acres — Undeveloped (Pasture/Woodland Areas) 4 "C" = 0.37 Drainage Area "P1" Runoff Coefficient "CWTD": 5.34 Acres — As reported in Drainage Study (1/23/06) 4 "C" =0.71 3.4 Time of Concentration: The Time -of -Concentration (Tc), for each watershed, is used to determine the intensity of the rainfall event for the corresponding drainage basin. Time -of -Concentration is defined as the time required for the surface runoff to flow from the most hydraulically remote point in a watershed to the point of analysis. The Tc is the summation of the flow time for overland sheet flow plus shallow overland flow and/or concentrated flow to the lower reach of the watershed. Overland sheet flow is a method developed by Overton and Meadows and is typically used for flow distances of 300 feet or less. Concentrated flows are estimated by velocities determined by use of the Manning's Equation. These two types of flow time calculations are further explained as follows. Overland Sheet Flow, Tt = (0.007 (n L)"I / (PiIIZ SOA) where, Tt = travel time (hours); n = Manning's roughness coefficient — This represents the flow -ability of runoff across a particular surface type and is a dimensionless coefficient. These coefficients are obtained from Table C-5 of the USDG; Pi = it, -year recurrence interval for the 24-hour rainfall depth (inches) — Rainfall depths are obtained from Table C-6 of the USDG; S = land slope (feet/foot) 197-0423 Drainage Report Page-6 M.D.W. Centre - Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 Shallow Concentrated Flow, Tt = D/(60V) where, Tt = Travel time (minutes); D = Flow distance (feet); V = Average velocity of runoff (ft/sec) - These values are determined from interpolation velocities recorded in Table C-4 of the USDG; Table #1 - "Tti-Overland Sheet Flow" and Table #2 - "Tt2-Shallow Concentrated Flow" illustrates the flow travel times for each segment of the sub -drainage basin in respect to the condition of the flow. The Te's for each sub -drainage basin where then computed and are summarized below in Table #3 - "Te Summary". TABLE #1 Ttl - Overland Sheet Flow Overland Average Flow Land Travel Drainage Manning's Distance Pi Slope Time Area I.D. "n" (L) 100- ear (S)(Tel Xl 0.33 44 11.0 0.0230 0.081 X2 0.42 77 11.0 0.0100 0.215 P1 0.33 42 11.0 0.0050 0.144 P2 0.42 77 11.0 0.0100 0.215 TABLE #2 Tt2 - Shallow and/or Concentrated Flow Shallow (Unpaved) Shallow (Channel 1) Shallow (Channel 2) Flow Average Flow Average Flow Average Drainage Distance Velocity Distance Velocity Distance Velocity Time Area I.D. (DI) VI(DI) (VI) D2 V2 Tc Xl 0 0.0 297 3.6 0 0.0 1.38 X2 531 2.9 643 1.9 477 3.5 10.96 Pi 0 0.0 465 2.2 0 0.0 3.52 P2 531 2.9 643 1.9 375 2.0 11.82 t) Unpaved Jhmlow stow average velocities were estimated using the following equation: V = 16.135*So'S where, V=fps S = average slope Assumptions - Manning's N = 0.05 & Hydraulic radius = 0.4 ft 2) Paved Shallow Flow average velocities were estimated using the following equation: V - 20.328*So 5 where, V=fps S = average slope Assumptions - Manning's N = 0.025 & Hydraulic radius = 0.2 ft 197-0423 Drainage Report Page-7 M.D.W. Centre — Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 TABLE #3 Te SUMMARY Combined Drainage Overland Channel Flow Tc Area I.D. Flow Time Time min Xl 0.081 1.38 16.2 X2 0.215 10.96 33.9 Pi 0.144 3.52 12.2 P2 0.215 11.82 34.7 1) The minimum Tc utilized for any drainage basin will be ten (10) minutes; 2) A time extension of 10 minutes was added to "X2" & "PT' to compensate for storage timing through the detention facility of the Grand Oaks Subdivision; 3.5 Stormwater Runoff Quantities: Stormwater runoff quantities were calculated, using the Rational Method with the assistance of the Hydrologic/Hydraulic stormwater modeling program HydroCAD. Runoff values for the larger watersheds are summarized below in Table #4 — "Drainage Basin Runoff Quantities". HydroCAD-Existing & Proposed Conditions Drainage Calculations and their supporting data are contained the "Attachment — Section 3.0" appendix of this Drainage Report. These calculated runoff quantities were reviewed and considered reasonable for the studied watershed. It should be noted that the runoff rates for Drainaee Area "Pl" are noticeable different (hieher) than what was comnuted and illustrated in Table 44 of the original report (1/23/06). This is due to a computational error with rainfall intensities was present in the original HydroCAD program. Other variations are primarily due to "better data" used for the hydrologic modeling of other drainage areas. Also, "benchmark" or target discharge rates for post -development conditions being metered from the detention facility was discussed earlier in Section 2.1 and 2.2. The following equation was utilized for calculating these target discharge rates (which will be the required maximum flow released from the detention pond) and are quantified below in Table #4. Target Discharge Equation: P2uETA@1Eo <_ (Xl+X2)-PI 197-0423 Drainage Report Page - 8 M.D.W. Centre - Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 TABLE #4 DRAINAGE BASIN RUNOFF QUANTITIES Drainage Drainage Rainfall Area Area Drainage Drainage Target Event (Xl) (X2) Area(Pl) Area(P2) Discharge ( r) (cfs) (cfs) (cfs) (cfs) (cfs) 2 6.40 15.96 16.72 16.65 5.64 5 7.79 19.40 20.33 20.25 6.86 10 8.74 21.78 22.82 22.72 7.70 25 9.98 24.87 26.07 25.95 8.78 50 11.28 28.12 29.47 29.34 9.93 100 1 11.78 29.35 30.77 30.63 1 10.36 Runoff values generated from the smaller sub -drainage areas, for purposes of modeling the existing/proposed storm sewer system, are not summarized in this section but are covered in the subsequent Section 5.0 - Storm Drainage System. 4.0 DETENTION FACILITY & ROUTING 4.1 Detention Facility Criteria STORAGE: 1. The storage ability of the detention facility is such that it can adequately detain the receiving stormwater runoff from upstream drainage areas so that runoff from the project site is controlled to pre -development "existing" conditions. The storage requirements are more fully explained in the following section; 2. The maximum storage depths for design and ultimate conditions shall be as follows: Facility Location Design HYdrogranh Ultimate Hydrogrra Parking Areas 0.50 ft 1.5 ft Rooftops 0.50 ft 1.0 ft Landscaped Areas 3.0 ft 4.50 ft 3. All detention facilities located on natural streams or water courses that are designed with a permanent storage component shall meet all criteria, in terms of design and construction, for Dams and Reservoirs as required by the Texas Commission on Environmental Quality (TCEQ); 4. Detention facilities shall have an additional 10% in storage to account for sedimentation, except those located in parking areas or rooftops. OUTLET STRUCTURES: The detention facility outlet structures are designed so that the system can be drained by means of gravity. Discharge velocities shall be verified that they are below the minimum velocities receivable by the type and nature of the receiving system or attenuated so that they are below these minimums. 197-0423 Drainage Report Page - 9 M.D.W. Centre— Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 PHYSICAL CHARACTERISTICS: 1. Side slopes shall not exceed 4:1 for vegetative cover and 2:1 for non -vegetative cover; 2. Bottom slopes must be 2.00% or steeper to low flow outlet; 3. A low -flow invert shall be provided for all facilities which have a vegetative cover at the facility bottom; EMERGENCY OVERFLOW: 1. The geometry of the emergency overflow shall be that of a rectangular weir; 2. Surface treatment of the overflow weir shall be consistent with the expected velocities at ultimate conditions. Proper treatments shall be provided to accommodate or attenuate the discharge velocities; 3. A minimum of 0.5 feet of freeboard shall be provided around the perimeter of the detention facility as measured between the maximum water surface elevation and the pool elevation and the ultimate conditions. 4.2 Methodology: The purpose of a detention facility is to store the increased runoff created by the impervious and improved areas, and discharge it at a rate so that the immediate downstream structure and/or property experiences decreases or no change as compared to existing conditions. Using the peak runoff rates, generated and illustrated in Section 3.5 of this report, hydrographs for each rainfall event and respective drainage basins were created for existing conditions. These hydrographs were constructed by means of triangular approximation method which is limited to smaller watersheds located within the secondary drainage system of a major watershed. Other assumptions and geometric conditions that are used to build these hydrographs are as listed below. Using this data, and inputting it into HydroCAD, approximate hydrographs were determined for each drainage basin at selected rainfall events. Triangular Approximation: 1. Peak Runoff (Q) occurs at "Tc' ; 2. The outflow portion of the triangular hydrograph is Tc x 2; Using this information, the storage volume of the detention facility can be estimated. This storage volume shall be such that the peak discharges of the development hydrograph, or the routed hydrograph, from the detention facilities will be equal to or less than the "Benchmark" and/or target discharges. These target discharges were discussed and computed in Section 3.5 and are contained within Table #4. 4.3 Detention Facility Configuration: The detention facility for the subject development will consist of one pond and will have a retention/water feature element. The detention facility, called Pond 1, will be installed with outlet structure system which will detain/meter (discussed in Section 4.5) increased runoff from Drainage Area "P2" and reduce them accordingly to the target discharge rates. The construction sheet .C1.2A: Site Grading & Drainage Plan for this project more My depicts these detention improvements/modifications and is contained under the 197-0423 Drainage Report Page -10 M.D.W. Centre —Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 "Attachment — Section 4.0" portion of this report. The detention facility is briefly summarized below: Pond 1: Runoff from Drainage Area "PT' is conveyed by means of an underground storm sewer system to the headworks of the detention facility. Pond 1 is "retention" pond and will have a normal pool elevation of 286.50'. The maximum berm or ponding elevations of the detention system will 291.00' which will also be the elevation at which the emergency spillway is engaged. Sideslopes of the detention pond will be near vertical retaining walls. Runoff routed through Pond 1 is metered through a horizontal orifice and then discharged into the downstream storm drainage system of the MDW Centre development. The discharge point is near the flowline of the unnamed tributary of Burton Creek that bisects the property. 4.4 Tailwater Considerations: The original drainage study (1/23/06) did not take into account tailwater consideration influencing the outlet structure of the detention pond by the unnamed tributary of Burton Creek. However, with this study tailwater consideration, for the discharge system of Pond 1, was made by frequencies of coincidental occurrence between the upstream watershed of the unnamed tributary and the corresponding subject drainage area "PT'. In the case a size ratio of contributing drainage areas of the primary system (unnamed tributary) vs. Pond 1 is at approximately 10:1. Therefore the following storm frequencies, in Table #5 — "Detention Facility Tailwater", were utilized for sizing of the outlet structure system of Pond 1. Actually WSE elevations are more fully explained below. Tailwater elevations, or water surface elevations, produced by the unnamed tributary, that influence the Pond 1 outlet structure system, were obtained from the flood study/HEC- RAS analysis (LOMR) discussed in Section 1.4 of this report. The most relavent studied cross-section that crosses the subject property, immediately downstream of the detention facility, is RS 21+94 with a calculated BFE of 286.62'. Since no other rainfall events were modeled, other than the 100-year flood, a "Straight Line" Tailwater was generated for the unnamed tributary for all other rainfall events. This estimation is not exact, but will avail a more realistic modeling approach for the detention facility outlet versus assuming fixed tailwater or free -flowing conditions. This information is also summarized below in Table #6 — "Straight Line Tailwater Estimations". 197-0423 Drainage Report Page - I 1 M.D.W. Centre — Detention Facility Modifications Drainage Study TABLE #5 DETENTION FACILITY TAILWATER Pond 1 Unnamed Unnamed Rainfall Tributary Tributary Event Rainfall Event W.S.E. (yr) (yr) (ft) 2 2 284.28 5 5 284.89 10 10 285.29 25 10 285.29 50 25 285.83 100 50 286.40 TABLE #6 STRAIGHT LINE TAILWATER ESTIMATION nname D.A. "X2" Tributary Rainfall Rainfall Channel Event Intensity W.S.E. (yr) (in/hr) (110 n/a 0.00 281.51 2 1.86 284.28 5 2.27 284.89 10 2.54 285.29 25 2.90 285.83 50 3.28 286.40 100 3.43 286.62 1) Datum information at the "zero" point, for the channel W.S.E. is the flowline of the tributary; 2) D.A. "X2" rainfall intensity was utilized and thus resulted with a straight line slope of m=1.49; RME Consulting Engineers October 3, 2011 4.5 Detention Facility Outlet Structure: The detention facility outlet structure has been designed to accommodate and route collected stormwater runoff, from Drainage Area "PT' so that during analyzed/routed rainfall events are restricted to a point at or less than the "benchmark" discharge values calculated. These "benchmark" discharge values are illustrated in Table #4 and contained in Section 3.5 of this report. The discharge structure system, for detention Pond 1, is summarized below: Primary Spillway; The primary spillway, or restricting orifice, will be a 12"xl2" square opening at the top of the junction box which will be tied into the existing 36" drainage outlet pipe. The top of this junction box will be set at an elevation of 286.50' which will also be the normal pool elevation of the retention component of the detention pond; 197-0423 Drainage Report Page -12 M.D.W. Centre - Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 Emergency Spillway The emergency spillway structure will consist of a ten -foot (10') wide existing drainage swale with rock rip -rap treatment at the downstream end of the detention/retention pond. This emergency structure will be engaged with the pond system reaches an elevation of 291.00'. The emergency spillway discharges directly into the unnamed tributary of Burton Creek; 4.6 Routing Results and Conclusions: Once the project's detention facility and outlet structure system was determined, then the hydrograph for Drainage Basins "P2" could be routed through the detention system. The routing of this hydrograph, for each analyzed rainfall event, was accomplished by means of the Hydrologic/Hydraulic stormwater modeling program HydroCAD. The program mathematically solves for continuity between the detention facilities storage capabilities, in respect to height versus storage and height versus discharge rate, with the inflow hydrograph and inputted tailwater conditions. HydroCAD - Proposed Conditions Pond Calculations - Pond 1 and its supporting data is contained the "Attachment - Section 4.0" section of this Drainage Report. An equivalent comparison of pre -development to post -development drainage areas is necessary to verify that the proposed detention facility is properly attenuating the increased impervious cover runoff. This attenuation of increased impervious cover was modeled at ultimate development conditions and the calculation of the necessary target discharges are discussed in Section 3.5 of this report. As shown below in Table #7 - "Detention Facility Routing", the designed detention facility system can accommodate inflow runoff and adequately detain this stormwater so that the facility's discharge rates are minimally below the "benchmark" discharges without surcharging the system. TABLE #7 DETENTION FACILITY ROUTING Routed Benchmark Diff. in Rainfall Storage Max. Discharge Discharge Discharge Max. Berm Event Volume Pool Elev Rate Rate Rate Elev. Freeboard (cu.ft) (ft) (cfs cfs) cfs ft ft) DETENTION POND I - ULTIMATE CONDITIONS 2 9,138 287.77 5.43 5.64 -0.21 290.00 2.23 5 11,657 288.03 5.97 6.86 -0.89 290.00 1.97 10 13,444 288.21 6.30 7.70 -1.40 290.00 1.79 25 15,817 288.45 6.72 8.78 -2.06 290.00 1.55 50 18,349 288.69 7.12 9,93 -2.81 290.00 1.31 too 19,326 288.78 7.27 10.36 -3.09 290.00 1.22 The discharge velocity, during the 25-year and 100-year rainfall event, from the combined 36" ADS pipe, will be approximately 3.0 fps and 3.2 fps respectively. Existing rock rip -rap, placed in concrete grout, is currently placed in -line with the outfall of this drainage pipe to mitigate any erosion. 197-0423 Drainage Report Page -13 M.D.W. Centre — Detention Facility Modifications Drainage Study 5.0 STORM DRAINAGE SYSTEM RMC Consulting Engineers October 3, 2011 The "system criteria" listed below in the follow sub -sections are only the main highlights of the design criteria utilized for this private storm sewer system. Please note that no inlet evaluations were conducted. All curb inlets are existing, but the new area inlet will be properly sized at development of the vacant property. 5.1 Storm Drain Conduits SYSTEM CRITERIA: 1. Storm drainage systems are designed to convey the design storm and analyzed during the 25-year rainfall event. A gravity over -flow route has been provided so that conduits that are unable to convey the 100-year storm can "spill" over into these over- flow systems so that situations that are hazardous to life, property, or public infrastructure is prevented; 2. For the design storm, the minimum flow velocity in a conveyance element shall not be less than 2.5 fps and not greater than 15.0 fps; 3. Roughness coefficients for storm sewer pipes were assigned at 0.012 for smooth -lined High Density Poly -Ethylene (HDPE) pipe and 0.013 for RCP; 4. Junction boxes were provided at all changes in conduit size and grade or alignment changes. Where junction box spacing exceeded 300 feet for 54" diameter pipe, or smaller, and 500' for pipes exceeding 54" in diameter, additional manhole were provided to maintain the desired spacing; 5. Storm sewer conduits with a diameter of 18" through 24" were hydraulically analyzed with a 25% reduction in cross -sectional area to compensate for potential partial blockage. Therefore 15" sized pipes were input as a 1.08' diameter pipe, 18" sized pipes were input as 1.30' diameter pipe, and 24" sized pipes were inputted as a 1.73' diameter pipe; 6. Conveyance elements were sized so that the design storm's hydraulic grade line would be equal to or less than grate inlet curb elevation; TAILWATER CONSIDERATIONS: Tailwater for the storm drainage system utilized the calculated pond elevations per Section 4.5 of this report. METHODOLGY & CONCLUSIONS: The hydraulic analysis, for storm drain conduits, and corresponding results, were determined by using the WINSTORM hydraulic program for stormwater modeling. This TxDOT program's typical use is for modeling gravity stormwater systems. The Winstorm data is summarized, for each system, under the Winstorm — Hydraulic Computations (reference "Attachment — Section 5.0" portion of the report). Storm drain conveyance elements and system, for the design storm (25-year rainfall event), are summarized below in Table #8 — "Storm Drainage Summary". 197-0423 Drainage Report Page -14 M.D.W. Centre - Detention Facility Modifications Drainage Study RME Consulting Engineers October 3, 2011 TABLE #8 STORM DRAINAGE SUMMARY Pipe Size US Top of US Node DS Node Diameter Velocity Capacity Runoff Q US HGL Curb Diff ID ID (in) (fps) cfs) cfs ft) Elev. ft (ft) 10-YEAR RAINFALL EVENT Al OI 36 10.62 72.37 41.65 290.76 297.50 -6.74 A2 Al 36 10.33 72.09 37.60 291.39 299.02 -7.63 A3 A2 24 11.81 32.85 34.66 293.53 300.60 -7.07 A4 A3 24 5.03 32.39 1.29 294.80 302.54 -7.74 A5 A3 18 27.25 44.77 33.27 297.19 300.60 -3.41 100-YEAR RAINFALL EVENT Al Ol 36 11.31 72.37 57.12 291.15 297.50 -6.35 A2 Al 36 11.09 72.09 51.56 291.74 299.02 -7.28 A3 A2 24 15.12 32.85 47.51 295.62 300.60 -4.98 A4 A3 24 5.48 32.39 1.74 295.63 302.54 -6.91 A5 A3 18 28.85 44.77 45.60 299.51 300.60 -1.09 1) The existing 18" pipe (between A3 & A5) is a private line that drains the detention facility of the Grand Oaks Subdivision into the public drainage system of Lincoln Avenue; 6.0 CERTIFICATION "This report for the drainage design of M.D.W. Centre (Detention Facility) - Wheeler Subdivision, Phase Two - Lot 2, Block One was prepared by me (or under my supervision) in accordance with provisions of the Bryan/College Station Unified Drainage Design Guidelines for the owners of the property. All licenses and permits required by any and all state and federal regulatory agencies for the proposed drainage improvements have been issued." i* *. RA60N METC / I . G � C.^'•��C'E ICI SF-�•'�� � l SS�ONALEN�„� �A Rabon Metcalf, P.E. State of Texas P.E. No. 88583 Texas Firm Registration No. F-4695 197-0423 Drainage Report Page -15 Section 1.0 GENERAL INFORMATION 1 \ •YDT -- Y Lac 11°W CFN7RE (9E7ENTON FAtlOTN: �' DRIVE 116D UNIVERSITY \ COLLEGE STATION, TEXAS W 9 xgw OR vowERLr �, A' H �„ d P R KYLE LEGEN05 1' I I w //,1,, ^ N 1 n (VCLUNE ABBR, PACE 291) ,`�/ �2• ",Y I/„ 1. N .8 PONT OFFICE BOX M311.210P<'11040> I TONED C-t V, �:•/ ?6• "``OLLEGE STATION, TION,T \ 7y. nj s/ PLAN COLLEGE el�a.wxXAS neax OFFICEX-(979)7644MHY/O4 h WHEELER SUBDIVISION, Lo IRPHASE TWO / \\ �� D ' NORTH PAX- 9T9 T9)764 R M.H. RON RETAMIND CALLEC: 1.10 ACRES ) // ' \ \%9' /14 �14i1 ` 30 TBXASFBHARCUISTMTIONNa l'4695 WALL w/RILYN: 2V SANITARY SEWER DMA).E 34M. PAGE 269 y\( Bcwn• as \ 10' U UTY 0 \ EASEHFNi (.190/590) 4/ T \ / EAEEM T TO' CIAO Y 4 / EASEMENT \ 1/2• I, q(J F (B90�s) B./ � � 3D• PnIVATE/Puauc / (xv3/xs0) \ \ w/CM • /. ACCEBg EASEMNT J 'P/ B Rla (HBO/TG9) ,0 � / / Iw� 0.{0 ACRE NA(/: AN. PN,VATE CEIENIIa �/ � \ I- •U• • k DRAINAGE EASEMENT / - x0' gANIEANY SEVER \ \O M•N• L.P. BOW/269) RECUND / EASEMENT (J99/690) VAULT IPoLA k BO% 6G 2 ROG. SET&LCK / L.P. \ +T a. / \9 w J SN MAC \s S[EBA p / OE ROOOWA ER \) • O mAmc Sox PARKIN RF(' DIIIRFIIFNIS:_ S 57',, / LOUR AEE \ cacNETE \ ' A 4 'O• DJ TE�n(LT 3) ®° M.x. LP Oft01NANCE: NEA9wIRWnu1HG `_ - e je \\ �I/z•I. �' RESTAURANT - I SPACE PER 86 SO.FT, 1 FOR AO'0 PIPEC 316.5 , L ®M,M. •� \ 2 M.H. vEgsA-LOX L2 (w/9 DRIVE THROUCN) MTE DEUAPn9x / BEINNING WALL " REQUIRED: 95%COMPLETE \ 1Y RESTAURANT TOTAL AREA-7,088 SOFT. / C (7,080 / 65) - 109 SPACES REVIEW ONLY ? 4✓ ��x , . s PROVIDED: NOT FOR x yI' ! La I I 1 VAN - 3 SPACES S CONSTRUCTION z/ EFX i c.n REWLAR H/C - 3 SPACES D:a�8y}WWs, :O/x\'n <O. 'Y S� n0., \ H[,LDWALWL TOTAL 1 9 SPACES 1013171 W � wAllE a• FOR x-{ro P I cYMeG�R IIryF [P�Fryp_ /Ll 0 POWER POLE - 1 ^ RO' Unutt � ytA _XI \lam GUY R V ANCHOR PRELIMINARY E WASRWArtN ��/��1 _ MNT WATER VALVE EASEMENT / \ % '\ Ay RESTAURANT - // ®EAR WATER METER THIS DOCUMENT E RELEASED _ Lv ELECTRICAL TRANSFORME0. r ER. (FOOTPRINT: 7,088 BO.FT.) / FOR THE PURPOSE AUTHORITYR THE I�5 (1-STONY) ON MANHOLE R REVIEW MASON DEA. METCAIFP.E. TIC.D. CLEANOUT NO. 843583, ON OCTOBER 3, WAY 1 DEVELOPMENT �3 j ` nx. - r x' FlRE HYDRANT 2011 R IS NOT TO BE USED T E / . ®M TELEPHONE PEDESTAL FOR CONSTRUCTION, BIDDING AREA (4],151 SQ.FTJ /\� T.D.C. I l ����' /�o / / OR AREA INLET OR PERMIT PURPOSES. �q}I9 JUNCTION BOX 91.CNRr / pA AREA UCHT (GRAND) jBigh• (31 o raoO �� �{n FIXEDCURB PIPE BOLLARD J.B.y1 _ CURB INLET /`BUILDING SETBACK LINE yL \ "O' /�,Y // .. _ PROPERTY UNE EASEMENT METUNE r • I I OI \ �/ p, n P.U.E. PU°UC UTUTYEASEMENT 1 MOOIFlEDO FApUTY w/RETA NINC 1B'%4:E. \ \ �\ / / SwM I 1 WALLS B LAND INC \ \ \ \ tV P.u.E. / STOPI Xx P.H. I / \ \i.(� \ \ (N00/BLAB) / CALLON onONYOUMOIG ? Z-F 0- lll--- \ \ ��QII /V W.V. (� i,. lEY$ OMfi GLL 9x51d AL E00-2E5-ISR Z Q O p= J 1 PHASE (D BWNDM; / I \� \ \� \ /s. / / uNIYW :x`xwwmoM"xA. n Dt �r S _ LANE J1,445 SOFT' \ GA LONE diAI C ' �1 (^, CA Bud\% € 01+�y~ FJH ORIGINAL PHASE ONE \J) \ N 1 BOUNDARY LINE 1 �ELECMICAL //�i11 H. SMB-WT ...,� JJJ ETAMILOW NN ETNNWC WALL I ' � /� ♦ l� CP h M� / ro Ac�'RG' dl BY P.U.E.(3490/269) P J� (dd� CIVIL SITE NOTES: ' ^ \ / i� ' 1. Pallas OF INNS BIIE VE AS GRAPHICALLY NW WE 1W-YEAR RME CALLED�DDSO ACRES TWO LINCOLN PLACE / \X` / ` / fiN. / MLN SDEPIPECS L OT RNA O LONR - N O NO. 0}OR-IORP SOAPED L TI Ol. 2. INC E SPECS LOCATED a EFMA iIRM CGNMUNIIY H0. {BMB.t, PANEL N0. Ot{R. (VOLUME RRS. PAGE 3R8) n/\ / ,[R / MVj MIDLAND AND EASEMENT ONES OVER AP ONLY WE UNIONIST xOw M EORUE Lv 1 1 ` T F•' / 2. MNEN WOODS Is sIMPRO RYAN D. It REX 0. PVLLER MUME JABS, PACE 2.) / .(� / 1 / - I •'/ 3, ME IMPROVEMENTS 910PE SHALL CONSTITUTE APPROAIMAIRY T0\ IHPERNWs 3. ZONED: R-1 \ \ SUBJECT COYEfl ON ME SUB.ECi PROPERTY. ' Of - LP. i S WI WAXER CURVE DATA: 4. A PAWING SETBACK VARPNM WAS GRANTED BY ME ZQVINO BOARD ADAISTHEMS (CAM PIE NO. M-RN). THIS VARIANCE ALLOWS A IV PAWNING R=656.00' 3ERMCN INSTEAD Of ST AlaO LINCON AVENUE MMIN ME MAERSTY GAME W ' D=62' 12' 41" OVERLAY WAGON. B. ME PURPOSE CfPHASE TWO DEVELOPMENT Ii0 ME GI. A /I A=712.28' A'WY a FACILITY T0 INCLUDE A WAWS FEAf AND AINGATaP_ LANCRCPVC • 1•/e6YxrLR. CHI) BEAR=S 14' 19' 01" W AND MEDIATES. 0. CONTRACTOR OE Ea ME CaiAINMFNi NID PROPER gBCK CASE, CAELE NAgNEH I ms9OSAL OFALL ualO AxO s0u0 w.1sTE AssaaATEo MM MIS PROSCT. ME ID M UD WASTE A CaMA01a SHALL USE ALL MEWS NECESSARY TO PREVENT ME MORRI ROE CE RA GI. MONO BLOWN UROM CITIES FME PAMCi SM. C.I. 7. ME CONTRACTOR SHAU BE REWIRED TO OPOE O TO WASTE A' WARN _ _ I To, .0 CCITT% DOW-Ra/GGING..... PR A.. COMMWBdLNDO'aT OFTEE/1ETK COMPETING SMALL BE BWPIRM BY OTY OR ON WANT . CE NMA01M(9) _ PROPERTY INFORMATION WHEELER SUBDIVISION PHASE TWO BLOCK 1, LOT 1 CALLED: 6.07 ACRES (VOL. 3490, PG. 269) NOW OR FORMERLY MAE DEAN WHEELER (VOL, 3490. PO. 269) ZONED C-1 w OVERLAY CORRIDOR I INC A! CURVE DATA `1DE BEARING (FT) LI S 18' 47 19 E 17.36 L2 N 73' 13' 19° E 19.41 W N 67' 44' 10• E 16.06' 1.4 S 17' 33' 41' E 22.90' pIA7 R OJOB I CHORD BEARING IF DELTA Cl I S 61- 47' 00' E-35.36' 1 25.00 59'59'22" TENT IxrDRNAM BEM WHEELERS, WC, RON COWE 1910 WHINEY SWEET, SCION, TROD MASON. Tx 77NO ONDMIN OftEELERCOMPATS"COM PH; (713) SW- a355 FX: (713) 3a5-IOB2 MENAWE:04235P1A SCLI SUBMITTED cuum. lonnl OMWN W. RA.M. CHECNED BY: RAM, FORD BOOM N A PIgF$:N A RARE CONSUL71NG ENGINEERS CLIENT NO. PROJECT NO, 197 - OQ,5 clA SHEET 4 OF 8 0 NE A NE X K9 ONE A ZONE X ZONE r� 6O I /City of College Station n 480083 11�& APPROXIMATE SCALE 600 0 500FEET M NATIONAL FLOOD INSURANCE PROGRAM FIRM FLOOD INSURANCE RATE MAP BRAZOS COUNTY, TEXAS AND INCORPORATED AREAS PANEL 142 OF 250 (SEE MAP INDEX FOR PANELS NOT PRINTED) CONTAINS: COMMUNITY NUMBER PANEL SUFFI% BRYAN, CITY OF 480082 0142 C COLLEGE STATION, CITY OF 480083 0142 C UNINCORPORATED AREAS 481195 0142 C Notice to User: The MAP NUMBER shown below should he used when placing map orders: the COMMUNITY NUMBER shown above should he used on insurance applications for the subject community, MAP NUMBER 48041CO142 C PA EFFECTIVE DATE: JULY 2, 1992 h*1edt!ral Emergency Management Agency This is an official copy of a portion of the above referenced flood map. It was extra using F-MIT Version 1.0. This map does not reflect changes or amendments whicl may have been made subsequent to the date on the title black. Fulher information about National Flood Insurance Program Rood hazard maps is available at PDF Create DaW 111912005 (c(eated at scale and type A) LOMR Update Ma 0101 .P SUMN:GR \a / I AP Nq ,J RsvgtG l�l( oR e �talvERsl,y. � SG'hM OR FN:[rR �i �s �-I UNIVERS((J OR 4 11Pp, ci=r O V 4v 'ly ArC Hr n CFI ov F a {c: ov c a,H eye Gyoe�= G r r �y Vic. SOi Pt " ype qS y' HeG O of Map fur references WIpf58s onNl Brazos County, The CIN of Bryan and The qy M Cdlege Station make no expressed or inplietl guarantee concerning the accuracy oftMslnfounallor 4,S Al E O �• T 17 ,r # J°kTy,'Dl; ���u CITY OF COL STATION �' ly ��i Bltl AA DISCLAIMER: This map is a product of the Cityof Bryan GIS Department developed with extensive cooperation between the City of Bryan, the Cityof College Station and Brazos County. All data, information, and maps are provided "as is" without warranty army representation of accuracy, timeliness of completeness. The burden for determining accuracy, completeness, timeliness, merchantability and fitness for or the appropriateness for use rests solely on the requester. The City of Bryan, the City of College Station and Brazos County make no warranties, express or implied, as to the use of the information obtained here. There are no implied warranties of merchantability or fitness for a particular purpose. The requester acknowledges and accepts all limitations, including the fact that the data, information, and maps are dynamic and in a constant state of maintenance, correction and update. Copyright 2003 - 2010 * City Of Bryan Geographic Information Services " P.OBOX 10011 :. Bryan, I 77305 Section 2.0 WATERSHEDS & DRAINAGE AREAS Feet 0 1 J300 3�00 7200 Figure B-6: Burton Creek Watershed Area =1 � S696-9'ON NOLLVd.LS108a KNIAS 'ON 6 nO POLO-09L(6L6) ILLIASNOO 3Wa W0191 WO-8' v/n :N006 MIA WOJ'I63n16YaWl'JU IIA�O - 'nvtl mNJ6H9 z49LL SMI'N0uns HO3 mm d NOIZNHEICI .40 d V i' 1L Vauv RDIY NIVU(I SNOI,I,I(imoo DNIISIXR (L6.O-0) SnOmum ® X I (C9'0-0) 1VUN30IS38 K11SN3a-1H011 — (WO-3) ('BM SWO ONWM) 03d011630Nn (090-0) SV3WV AVM-30-1HOW \ (LE-0-0) ONV1000M 03dOIM3014n 1 ISi1313Wtl8Vd '11 ONIMOIIOJ 3HL NOW 03SV8 JJONn 3130 3 OM S1N3101JJ3 IT I1 JJONn21 31150dW0O '£ I 'SV38V 3aVNlvaa MV a0J 001413104 IVNOLLV8 3H1 ONLIOldW3 AS 03NIW8313a 3a3M S3nIVA JJONnN z \ 'S833NION3 ONLLInSNOO — - MN AS a310480J83d A3A?JnS "1VOIHdVNOOd01 V WONJ 03SVB SI NMOHS viva 8nO1NOO 3HL I / 'sIUN Jee3A3<s II \. I SC'BL BL'll. 001 Lraz az•li 09 19'4Z 9616 94 9c•lz 4L•9 01 04'61 SCL 9 - 96.91 019 z (SA) zX 'VIC (W) IX 'tl'0 (Nl) 1NM3 TV3Ntvv 6'SC 29'0 9ll% LX Z191 LC'0 44'b IX (ol) l NnL 031H013N V38tl tl3SV 3Oy3my AavWWnS 0100IOaa H Ir M01A 133HS 1 \ aw uo)g!^Ip9nS sj✓O p ou a0 / / MOIJ 0 HLVQMOIJ aad ' IIZX/II)•V*G / I ) 1 All Otld I \ + 0 b2 k 1 � I � - III -•�� + 4 't� \ 3d0IS Xz'£ O ,l£9=0 LJ4 (AVMN3IVM a3SSY80) lMOId a3ivHLN3ONOO I \ ti MOIIVHS-HLVd MOIJ - -___ _i -_- _ A \�� ---- It O + I I j 3d01: 1 / I I(.kVM83LVM SSVN + O) MOId 133H$ �� ' `---' --'' \\ %\ / i aNVn1V81t0-HLVd MOIJ / '9l.¢It 3d0IS XI'9 '°•-•"T"'tl �� / �' / / I I ().VM831tlM 03 \ r' `/ / /r \ I / i / j i MOIJ 031V2llP i \��\/'I KOIIVHS-HLVI ' \ i %OIXu 3 VNNn \> ' OW38 ISM i - \ 1 0 °a I YA / V a3H 0 rva015 ONLLSIX3 / / ExISTINO_. \% / 2-48"0 RCP / STORM SEWER 1 1 .6 / I \ \ 1 1 1 l \\, FLOW PATH -CHANNEL / i / i / .'' l ,- / _ _ ` `— //'♦ i—� / �\ FLOW CCHANNEL) i i .'' �'� — / ---- D-465 ® 1.2% SLOPE 1 `./ � i i I � / �1ry• I �O - FLOW PATH -OVERLAND / I + \ SHEET FLOW (GRASS `\ WATERWAY) ______ // \\ i 9�° _- D=42' ® 0.5% SLOPE ,[� / .� /J l l + o EXISTING 24"/ M—' ) 10 RCP STORM / II SEWS/ \ / I FLOW PATH -SHALLOW \ ' CONCENTRATED FLOW \ I (GRASSED WATERWAY) D=531' O 3.2X SLOPE 1 I � I ` IW116 GRAND �\ OAKS DETENTION/' � \I FAgL1TY 11 j I / RAJ t1P211 J ARE/".05 / FLOW PATH -CHANNEL FLOW (CHANNEL) D-643' 6 0.9X SLOPE / Grand 0 ks Subdivision / , I +° 1 SHEET FLOW I \\ II GENERAL NOTES: 1. THE CONTOUR DATA SHOWN IS / BASED FROM A TOPOGRAPHICAL SURVEY PERFORMED BY RME CONSULTING ENGINEERS. 2. RUNOFF VALUES WERE \ DETERMINED BY EMPLOYING THE RATIONAL METHOD FOR ALL DRAINAGE AREAS, 3, COMPOSITE RUNOFF COEFFICIENTS WERE DETERMINED 1 BASED FROM THE FOLLOWING 1 I PARAMETERS: 1 ` UNDEVELOPED WOODLAND (C-0.37) \\ `, RIGHT-OF-WAY AREAS (C-0.40) \ ` UNDEVELOPED (GRAND OAKS SUB.) (C-0.44) 1 \ LIGHT -DENSITY RESIDENTIAL (C-O.BJ) J ®CdINFAgAI DEVELOPED (O.R. I/23/08) (C-OJI) X® IMPERMOUS (C-0.82) ROPOSED CONDITION DRAINAGE AREA MAP DE HYDROLOGIC SUMMARY DRAINAGE MCA AREA (AC) WEIGHTED RUNOFF C(wl4) T. (MIN) PI 4.55 0.71 12.2 P2 1e.05 0.56 34.7 RAINFALL EVENT (YR) O.A. PI (CFS) D.A. P2 (CFS) 2 16.72 16.65 5 20.33 20.25 10 22.82 22.72 25 25.07 25.95 50 29.47 28.34 100 30,77 'J0,83 cww kw vmoia. E STATION, TEXAS 77842 olvil®�man8inear.wm 4979)764-0704 JUm poo 11 v �i li V Av v i D.A. lip lit AREA=�.55.AC p 0 20 10 F1 C I \ V t py � I I CN I 1 GENERAL NOTES: 1. THE CONTOUR DATA SHOWN 13 B BASED FROM A TOPOGRAPHICAL // I �• \ / /,/ \II -- 1 ,I. I \ SURVEY PERFORMED BY VANNOY & ASSOCIATES, INC, 2. RUNOFF VALUES WERE DETERMINED BY EMPLOYING THE RATIONAL METHOD. j / o) / \\\ : 11 3. WEIGHTED RUNOFF COEFFICIENTS WERE DETERMINED BASED FROM THE I I FOLLOWING PARAMETERS: �• /I PARK DETENTION FACILITY ,f I Ii�ll _ \ (C=0.40) .� I � FUTURE w/DETENTION FACILITY (C=0.45) HIGH —DENSITY RESIDENTIAL (C-0.65) COMMERCIAL/OFFICE (C=0,75) N,I / PAVEMENT (C=0.96) ouaEr 'o1" �\\� PIPE 2 II / \ 4. ALL DRAINAGE AREAS UTILIZED PIPE I pv I li A MINIMUM TIME OF CONCENTRATION /I/ / .,- i \ I .\\ \ (TO) OF 10 MINUTES. — — — _ _ _ AI Al ��� �i II 5. THE POST —DEVELOPMENT AREAS !; I _ t�l I— % (� Az PIPE 3 DEPICTED ARE APPROXIMATIONS OF ( I I HOW SITE GRADING MAY REDIRECT .� RUNOFF TO THE STREET STORM aA2I A5 I DRAINAGE SYSTEM. THIS l, I I APPROXIMATION IS CONSIDERED TO II II BE A CONSERVATIVE ESTIMATE. A r I I I D.A. P2 AREA=16.05 AC I�AS I I I I \. / I //I I L /-/ / I I r� II \Jr__ ---,---- ---- - -�_ -'' J STORM SEWER \ Q1 I _ I DRAINAGE AREA MAP \ \ k— — — _ J L f " I I I PIPE OF M.D.W. CENTRE \ --- -------- I i if I DETENTION FACILITY WHEELER SUBDIVISION PHASE TWO 2, BLOCK — _ _ _ _ COLLEGEGSTATION. BRAZOS COVMY, TEXAS BER1 NHEELORR. INC. `\� / \ P \ I ` _ l l l{ \: eIo RON COWE III111 — — — — — — — — \ / A4 1919 WHIiNE STREET, SURE 0900 HOUSTON, TX 7700 �` / / , / —• mil} // /. E PH, C(] 31 M-5355 MPNIIES.COM PX: (7M) 355-1o52 V / l / 1 :'_."'• �"""._-- / r ` MLENANE: 0423x3n 5r .V-50' 7607 EASTMARK DR., STE. 250F<7840, RMSroNES DATE:09/11 I POST OFFICE BOX 9253 / COLLEGE STATION, TEXAS 77842 DRAWN W. RAN. LNECXEU BY. RANI EMAIL, civilQrmengineecco'0 mo Boo,: x/A PAD25: N/A OFFICE.(979) 764.07M RIVE CONSULTING ENGINEERS I TEXAS FIRM REGISTRATION NO, F-4695 CLIENT 7 G, - 0423 G. Section 3.0 HYDROLOGIC MODELING HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by {enter your company name here} page 1 HvdroCAD® 7.10 s/n 003394 © 2005 HvdroCAD Softwara Sohitinnc I I C op�onn41 Time span=0.00-1.00 hrs, dt=0.01 hrs, 101 points Runoff by Rational method, Rise/Fall=1.0/2.0 xTc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment DA-PI: Post -Development "P1" Subcatchment DA-P2: Post -Development P2 Subcatchment DA-X1: Pre -Development "X1" Runoff Area=4.550 ac Runoff Depth=0.92" Tc=12.2 min C=0.71 Runoff=16.72 cfs 0.349 of Runoff Area=16.050 ac Runoff Depth=0.26" Tc=34.7 min C=0.57 Runoff=16.65 cfs 0.347 of Runoff Area=4.440 ac Runoff Depth=0.36" Tc=16.2 min C=0.37 Runoff=6.40 cfs 0.134 of Subcatchment DA-X2: Pre -Development "X2" Runoff Area=16.160 ac Runoff Depth=0.25 Tc=33.9 min C=0.53 Runoff=15.96 cfs 0.333 of Total Runoff Area = 41.200 ac Runoff Volume = 1.163 of Average Runoff Depth = 0.34" HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by {enter your company name here) Page 2 HydroCAD®? 10 s/n 003394 02005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P1: Post -Development "P1" [481 Hint: Peak<CiA due to short duration Runoff = 16.72 cfs @ 0.17 hrs, Volume= 0.349 af, Depth= 0.92" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Area (ac) C Description 4.550 0.71 Post -Development Conditions Tc Length Slope Velocity Capacity Description 12.2 Direct Entry, Proposed Conditions Subcatchment DA-PI: Post -Development "P1" Hydrograph — Runoff TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Runoff Area=4.550 ac Runoff Volume=0.349 of Runoff Depth=0.92" Tc=12.2 min C=0.71 HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by {enter your company name here} Page 3 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P2: Post -Development P2 [48] Hint: Peak<CiA due to short duration Runoff = 16.65 cfs @ 0.17 hrs, Volume= 0.347 af, Depth= 0.26" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Area (ac) C Description 16.050 0.57 Post -Development Conditions Tc Length Slope Velocity Capacity Description 34.7 Direct Entry, Proposed Conditions 0 Subcatchment DA-P2: Post -Development P2 Hydrograph TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Runoff Area=16.050 ac Runoff Volume=0.347 of Runoff Depth=0.26" Tc=34.7 min C=0.57 nme �nours� —Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by (enter vour company name here} Page 4 Co] Subcatchment DA-X1: Pre -Development "X1" [481 Hint: Peak<CiA due to short duration Runoff = 6.40 cfs @ 0.17 hrs, Volume= 0.134 af, Depth= 0.36" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Area (ac) C Description 4.440 0.37 Pre -Development Conditions Tc Length Slope Velocity Capacity Description 16.2 Direct Entry, Existing Conditions Subcatchment DA-XI: Pre -Development "X1" Hydrograph — Runoff / TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Runoff Area=4.440 ac Runoff Volume=0.134 of Runoff Depth=0.36" Tc=16.2 min C=0.37 ime (nouml HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by {enter your company name here} Page 5 HydroCADO 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X2: Pre -Development "X2" [48] Hint: Peak<CiA due to short duration Runoff = 15.96 cfs @ 0.17 hrs, Volume= 0.333 af, Depth= 0.25" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Area (ac) C Description 16.160 0.53 Existing Conditions Tc Length Slope Velocity Capacity Description 33.9 Direct Entry, Existing Conditions Subcatchment DA-X2: Pre -Development "X2" Hydrograph —Runoff TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Runoff Area=16.160 ac Runoff Volume=0.333 of Runoff Depth=0.25" Tc=33.9 min C=0.53 Time (hours) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Prepared by (enter your company name here) Page 6 Time span=0.00-1.00 hrs, dt=0.01 hrs, 101 points Runoff by Rational method, Rise/Fall=1.0/2.0 xTc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment DA-P1: Post -Development "P1" Subcatchment DA-P2: Post -Development P2 Subcatchment DA-X1: Pre -Development "X1" Subcatchment DA-X2: Pre -Development "X2" Runoff Area=4.550 ac Runoff Depth=1.12" Tc=12.2 min C=0.71 Runoff=20.33 cfs 0.424 of Runoff Area=16.050 ac Runoff Depth=0.32" Tc=34.7 min C=0.57 Runoff=20.25 cfs 0.422 of Runoff Area=4.440 ac Runoff Depth=0.44" Tc=16.2 min C=0.37 Runoff=7.79 cfs 0.162 of Runoff Area=16.160 ac Runoff Depth=0.30" Tc=33.9 min C=0.53 Runoff=19.40 cfs 0.405 of Total Runoff Area = 41.200 ac Runoff Volume = 1.414 of Average Runoff Depth = 0.41" HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Prepared by {enter your company name here} Page 7 U-A,.n A n( 7 nn -I- nnOO !' nnnc 1 Am _.__._ Subcatchment DA-PI: Post -Development "P1" [481 Hint: Peak<CiA due to short duration Runoff = 20.33 cfs @ 0.17 hrs, Volume= 0.424 af, Depth= 1.12" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Area (ac) C Description 4.550 0.71 Post -Development Conditions Tc Length Slope Velocity Capacity Description 12.2 Direct Entry, Proposed Conditions Subcatchment DA-P1: Post -Development "P1" Hydrograph — Runof( TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Runoff Area=4.550 ac Runoff Volume=0.424 of Runoff Depth=1.12" Tc=12.2 min C=0.71 ..... w vIDUM) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Prepared by {enter your company name here} Page 8 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P2: Post -Development P2 [48] Hint: Peak<CiA due to short duration Runoff = 20.25 cfs @ 0.17 hrs, Volume= 0.422 af, Depth= 0.32" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Area (ac) C Description 16.050 0.57 Post -Development Conditions Tc Length Capacity Description 34.7 Direct Entry, Proposed Conditions Subcatchment DA-P2: Post -Development P2 Hydrograph TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Runoff Area=16.050 ac Runoff Volume=0.422 of Runoff Depth=0.32" Tc=34.7 min C=0.57 nme knours, — Runofl HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Prepared by {enter your company name here) Page 9 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-XI: Pre -Development "X1" [48] Hint: Peak<CiA due to short duration Runoff = 7.79 cfs @ 0.17 hrs, Volume= 0.162 af, Depth= 0.44" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Area (ac) C Description 4.440 0.37 Pre -Development Conditions Tc Length Description 16.2 Direct Entry, Existing Conditions Subcatchment DA-X1: Pre -Development "XII" Hydrograph — RunoH TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Runoff Area=4.440 ac Runoff Volume=0.162 of Runoff Depth=0.44rr Tc=16.2 min C=0.37 Time (hours) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Prepared by {enter your company name here} Page 10 HvdrnCAn RO 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X2: Pre -Development "X2" [481 Hint: Peak<CiA due to short duration Runoff = 19.40 cfs @ 0.17 hrs, Volume= 0.405 at, Depth= 0.30" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Area (ac) C Description 16.160 0.53 Existing Conditions Tc Length Slope Velocity Capacity Description 33.9 Direct Entry, Existing Conditions Subcatchment DA-X2: Pre -Development ' X2" Hydrograph TX -Brazos County 5-Year Duration=10 min, Inten=7.69 in/hr Runoff Area=16.160 ac Runoff Volume=0.405 of Runoff Depth=0.30" Tc=33.9 min C=0.53 me (nours) — Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 10-Year Duration=10 min, lnten=8.63 in/hr Prepared by {enter your company name here} Page 11 u. A-n AM( 7 An -I- nn9gn,f lA onnc u,,A-n An C..N..•..... C..L .H...... I In n/nn/nA44 Time span=0.00-1.00 hrs, dt=0.01 hrs, 101 points Runoff by Rational method, Rise/Fall=1.0/2.0 xTc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment DA-P1: PostZevelopment "P1" Subcatchment DA-P2: Post -Development P2 Subcatchment DA-XI: Pre -Development "X1" Subcatchment DA-X2: Pre -Development "X2" Runoff Area=4.550 ac Runoff Depth=1.26" Tc=12.2 min C=0.71 Runoff=22.82 cfs 0.476 of Runoff Area=16.050 ac Runoff Depth=0.35" Tc=34.7 min C=0.57 Runoff=22.72 cfs 0.474 of Runoff Area=4.440 ac Runoff Depth=0.49" Tc=16.2 min C=0.37 Runoff=8.74 cfs 0.182 of Runoff Area=16.160 ac Runoff Depth=0.34" Tc=33.9 min C=0.53 Runoff=21.78 cfs 0.454 of Total Runoff Area = 41.200 ac Runoff Volume = 1.587 of . Average Runoff Depth = 0.46" HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Prepared by {enter your company name here} Page 12 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P1: Post -Development "P1" [48] Hint: Peak<CiA due to short duration Runoff = 22.82 cfs @ 0.17 hrs, Volume= 0.476 af, Depth= 1.26" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Area (ac) C Description 4.550 0.71 Post -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.2 Direct Entry, Proposed Conditions Subcatchment DA-P1: Post -Development "P1" Hydrograph — Runoff TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Runoff Area=4.550 ac Runoff Volume=0.476 of Runoff Depth=1.26rr Tc=12.2 min C=0.71 Time (hours) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational-09091 1 TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Prepared by {enter your company name here} Page 13 Subcatchment DA-P2: Post -Development P2 [48] Hint: Peak<CiA due to short duration Runoff = 22.72 cfs @ 0.17 hrs, Volume= 0.474 af, Depth= 0.35" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Area (ac) C Description 16,050 0.57 Post -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 34.7 Direct Entry, Proposed Conditions Subcatchment DA-P2: Post -Development P2 Hydrograph — Runaff TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr - - Runoff Area=16.050 ac Runoff Volume=0.474 of Runoff Depth=0.35" Tc=34.7 min C=0.57 Time (hours) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Prepared by {enter your company name here} Page 14 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-XI: Pre -Development "X1" (481 Hint: Peak<CiA due to short duration Runoff = 8.74 cfs @ 0.17 hrs, Volume= 0.182 af, Depth= 0.49" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Area (ac) C Description 4.440 0.37 Pre -Development Conditions Tc Length Slope Velocity Capacity Description 16.2 Direct Entry, Existing Conditions Subcatchment DA-XI: Pre -Development "X1" Hydrograph TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Runoff Area=4.440 ac Runoff Volume=0.182 of Runoff Depth=0.49" Tc=16.2 min 19MI CIN 0 Time (hours) — Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational -090911 TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Prepared by {enter your company name here} Page 15 HydroCADO 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X2: Pre -Development "X2" [48) Hint: Peak<CiA due to short duration Runoff = 21.78 cfs @ 0.17 hrs, Volume= 0.454 af, Depth= 0.34" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Area (ac) C Description 16.160 0.53 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 33.9 Direct Entry, Existing Conditions Subcatchment DA-X2: Pre -Development "X2" Hydrograph TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Runoff Area=16.160 ac Runoff Volume=0.454 of Runoff Depth=0.34" Tc=33.9 min C=0.53 Time (hours) — Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Prepared by {enter your company name here} Page 16 HydroCAD®7 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Time span=0.00-1.00 hrs, dt=0.01 hrs, 101 points Runoff by Rational method, Rise/Fall=1.0/2.0 xTc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment DA-PI: Post-Development"PI" Subcatchment DA-P2: Post -Development P2 Subcatchment DA-X1: Pre -Development "X1" Subcatchment DA-X2: Pre -Development "X2" Runoff Area=4.550 ac Runoff Depth=1.43" Tc=12.2 min C=0.71 Runoff=26.07 cfs 0.544 of Runoff Area=16.050 ac Runoff Depth=0.40" Tc=34.7 min C=0.57 Runoff=25.95 cfs 0.541 of Runoff Area=4.440 ac Runoff Depth=0.56" Tc=16.2 min C=0.37 Runoff=9.98 cfs 0.208 of Runoff Area=16.160 ac Runoff Depth=0.39" Tc=33.9 min C=0.53 Runoff--24.87 cfs 0.519 of Total Runoff Area = 41.200 ac Runoff Volume = 1.812 of Average Runoff Depth = 0.63" HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Rev ised-Rational-090911 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Prepared by }enter your company name here} Page 17 Subcatchment DA-PI: Post -Development "P1" [48] Hint: Peak<CiA due to short duration Runoff = 26.07 cfs @ 0.17 hrs, Volume= 0.544 af, Depth= 1.43" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Area (ac) C Description 4.550 0.71 Post -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.2 Direct Entry, Proposed Conditions Subcatchment DA-P1: Post -Development "P1" Hydrograph TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Runoff Area=4.550 ac Runoff Volume=0.544 of Runoff Depth=1.43" Tc=12.2 min C=0.71 rime (hours) —Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rati onal-09091 1 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Prepared by (enter your company name here) Page 18 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P2: Post -Development P2 [48] Hint: Peak<CiA due to short duration Runoff = 25.95 cfs @ 0.17 hrs, Volume= 0.541 af, Depth= 0.40" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Area (ac) C Description 16.050 0.57 Post -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 34.7 Direct Entry, Proposed Conditions Subcatchment DA-P2: Post -Development P2 Hydrograph TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Runoff Area=16.050 ac Runoff Volume=0.541 of Runoff Depth=0.40" Tc=34.7 min C=0.57 me (nours) — Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Prepared by {enter your company name here} Page 19 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X1: Pre -Development "X1" [48] Hint: Peak<CiA due to short duration Runoff = 9.98 cfs @ 0.17 hrs, Volume= 0.208 af, Depth= 0.56" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Area (ac) C Descriotion 4.440 0.37 Pre -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.2 Direct Entry, Existing Conditions Subcatchment DA-XI: Pre -Development "X1" Hydrograph TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Runoff Area=4.440 ac Runoff Volume=0.208 of Runoff Depth=0.56" Tc=16.2 min C=0.37 Tlme (hours) — Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational-090911 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Prepared by {enter your company name here} Page 20 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X2: Pre -Development "X2" [48) Hint: Peak<CiA due to short duration Runoff = 24.87 cfs @ 0.17 hrs, Volume= 0.519 af, Depth= 0.39" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Area (ac) C Description 16.160 0.53 Existing Conditions Tc Length Slope Velocity Capacity Description 33.9 Direct Entry, Existing Conditions N 3 M Subcatchment DA-X2: Pre-Development'W" Hydrograph '" I / \ TX -Brazos County 25-Year 'z Duration=10 min, ,o_ Inten=9.86 in/hr 18- Runoff Area=16.160 ac 16- 14- Runoff Volume=0.519 of z_ Runoff Depth=0.39" o- Tc=33.9 min 8 C=0.53 Time (hours) — Runaff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here} Page 21 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Time span=0.00-1.00 hrs, dt=0.01 hrs, 101 points Runoff by Rational method, Rise/Fall=1.0/2.0 xTc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment DA-PI: Post -Development "PI IN Subcatchment DA-P2: Post -Development P2 Subcatchment DA-X1: Pre -Development "X1" Subcatchment DA-X2: Pre -Development "X2" Runoff Area=4.550 ac Runoff Depth=1.62" Tc=12.2 min C=0.71 Runoff=29.47 cfs 0.615 of Runoff Area=16.050 ac Runoff Depth=0.46" Tc=34.7 min C=0.57 Runoff=29.34 cfs 0.612 of Runoff Area=4.440 ac Runoff Depth=0.64" Tc=16.2 min C=0.37 Runoff=11.28 cfs 0.235 of Runoff Area=16.160 ac Runoff Depth=0.44" Tc=33.9 min C=0.53 Runoff=28.12 cfs 0.587 of Total Runoff Area = 41.200 ac Runoff Volume = 2.049 of Average Runoff Depth = 0.60" HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here) Page 22 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P1: Post -Development "P1" [481 Hint: Peak<CiA due to short duration Runoff = 29.47 cfs @ 0.17 hrs, Volume= 0.615 af, Depth= 1.62" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Area (ac) C Description 4,550 0.71 Post -Development Conditions Tc Length Slope Velocity Capacity Description 12.2 Direct Entry, Proposed Conditions Subcatchment DA-P1: Post -Development "P1" Hydrograph — RunoN TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Runoff Area=4.550 ac Runoff Volume=0.615 of Runoff Depth=1.62" Tc=12.2 min C=0.71 iime tnours, HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here} Page 23 Subcatchment DA-P2: Post -Development P2 [48] Hint: Peak<CiA due to short duration Runoff = 29.34 cfs @ 0.17 hrs, Volume= 0.612 af, Depth= 0.46" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Area (ac) C Description 16.050 0.57 Post -Development Conditions Tc Length Description 34.7 Direct Entry, Proposed 0 Subcatchment DA-P2: Post -Development P2 Hydrograph / TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Runoff Area=16.050 ac Runoff Volume=0.612 of Runoff Depth=0.46" Tc=34.7 min C=0.57 ine (nours) — Runof! HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here} Page 24 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-XI: Pre -Development "X1" [481 Hint: Peak<CiA due to short duration Runoff = 11.28 cfs @ 0.17 hrs, Volume= 0.235 af, Depth= 0.64" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Area (ac) C Description 4.440 0.37 Pre -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.2 Direct Entry, Existing Conditions Subcatchment DA-X1: Pre -Development "X1" Hydrograph —Runoff / \ TX -Brazos County 50-Year / Duration=10 min, Inten=11.15 Whir Runoff Area=4.440 ac Runoff Volume=0.235 of Runoff Depth=0.64" Tc=16.2 min C=0.37 Time (hours) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here) Page 25 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X2: Pre -Development "X2" [48] Hint: Peak<CiA due to short duration Runoff = 28.12 cfs @ 0.17 hrs, Volume= 0.587 af, Depth= 0.44" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Area (ac) C Description 16.160 0.53 Existing Conditions Tc Length Slope Velocity Capacity Description 33.9 Direct Entry, Existing Conditions Subcatchment DA-X2: Pre -Development "X2" Hydrograph TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Runoff Area=16.160 ac Runoff Volume=0.587 of Runoff Depth=0.44" Tc=33.9 min C=0.53 Time (hours) — RunoH HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 26 Time span=0.00-1.00 hrs, dt=0.01 hrs, 101 points Runoff by Rational method, Rise/Fall=1.0/2.0 xTc Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment DA-PI: Post -Development "P1" Subcatchment DA-P2: Post -Development P2 Subcatchment DA-XI: Pre -Development "X1" Subcatchment DA-X2: Pre -Development "X2" Runoff Area=4.550 ac Runoff Depth=1.69" Tc=12.2 min C=0.71 Runoff=30.77 cfs 0.642 of Runoff Area=16.050 ac Runoff Depth=0.48" Tc=34.7 min C=0.57 Runoff=30.63 cfs 0.639 of Runoff Area=4.440 ac Runoff Depth=0.66" Tc=16.2 min C=0.37 Runoff=11.78 cfs 0.246 of Runoff Area=16.160 ac Runoff Depth=0.45 Tc=33.9 min C=0.53 Runoff=29.35 cfs 0.612 of Total Runoff Area = 41.200 ac Runoff Volume = 2.139 of Average Runoff Depth = 0.62" HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational -09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 27 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P1: Post -Development "P1" [481 Hint: Peak<CIA due to short duration Runoff = 30.77 cfs @ 0.17 hrs, Volume= 0.642 af, Depth= 1.69" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Area (ac) C Description 4.550 0.71 Post -Development Conditions Tc Length Description 12.2 Direct Entry, Proposed Conditions n Subcatchment DA-PI: Post -Development "P1" Hydrograph TX -Brazos County 100-Year - Duration=10 min, Inten=11.64 in/hr rime (hours) Runoff Area=4.550 ac Runoff Volume=0.642 of Runoff Depth=1.69" Tc=12.2 min C=0.71 — Runoff HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational-09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 28 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-P2: Post -Development P2 [48] Hint: Peak<CiA due to short duration Runoff = 30.63 cfs @ 0.17 hrs, Volume= 0.639 af, Depth= 0.48" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Area (ac) C Description 16.050 0.57 Post -Development Conditions Tc Length Slope Velocity Capacity Description 34.7 Direct Entry, Proposed Conditions Subcatchment DA-P2: Post -Development P2 Hydrograph TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Runoff Area=16.050 ac Runoff Volume=0.639 of Runoff Depth=0.48" Tc=34.7 min C=0.57 i ne (nouns) — Runoft HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised-Rational-09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 29 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X1: Pre -Development "X1" [48] Hint: Peak<CiA due to short duration Runoff = 11.78 cfs @ 0.17 hrs, Volume= 0.246 af, Depth= 0.66" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Area (ac) C Descriotion 4.440 0.37 Pre -Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 16.2 Direct Entry, Existing Conditions Subcatchment DA-X1: Pre -Development "X1" Hydrograph — Runoff TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Runoff Area=4.440 ac Runoff Volume=0.246 of Runoff Depth=0.66" Tc=16.2 min C=0.37 Time (hours) HydroCAD-Existing & Proposed Conditions Drainage Calculations MDW Revised -Rational -09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 30 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/29/2011 Subcatchment DA-X2: Pre -Development "X2" [48] Hint: Peak<CiA due to short duration Runoff = 29.35 cfs @ 0.17 hrs, Volume= 0.612 af, Depth= 0.45" Runoff by Rational method, Rise/Fall=1.0/2.0 xTc, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Area (ac) C Description 16.160 0.53 Existing Conditions Tc Length Description 33.9 Direct Entry, Existing Conditions Subcatchment DA-X2: Pre -Development "X2" Hydrograph \ TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Runoff Area=16.160 ac Runoff Volume=0.612 of Runoff Depth=0.45" Tc=33.9 min C=0.53 Time (hours) — RunoH Section 4.0 DETENTION FACILITY & ROUTING PLAN NOTES: I. REFER TO SHEET CO.1 FOR GRADING, DRAINAGE, AND MISCELLANEOUS CONSTRUCTION NOTES. 2, REFER TO SHEET C2.1 k C2,2 FOR GRADING, DRAINAGE @ MISCELLANEOUS DETAILS. PROJECT BENCHMARK- GPS MONUMENT NO. 122 - ALUMINUM CAP SET IN CONCRETE, STAMPED COLLEGE STATION MON. 122. 1980. LOCATED ON THE EAST SIDE OF UNIVERSITY BLVD. NEAR ITS SOUTHWEST CORNER IMTH TARROW STREET. (ELEV.-329,9]' - NOW 1929) TS.M. JIL TOP NUT OF FIRE HYDRANT LOCATED ON THE NORTH SIDE OF UNCOLN AVENUE. APPROXIMATELY 5V WEST OF ME SOUTHWEST CORNER OF LOT 1, BLOCK 1 OF THE WHEELER SUBDIVISION, PHASE TWO (EIEV.-304,/0) T.R.M. 0- TOP NUT OF FIRE HYDRANT LOCATED AT THE SOUTHEAST CORNER OF ME AMERISUITES HOTEL. APPROXIMATELY 60' NW OF ME SOUTHEAST CORNER OF LOT 1fl BLOCK 1 OF ME WHEELER SUBDIVISION, PHASE TWO (EaV.-295,Oa') GRADING LEGEND DRAINAGE DIRECTIONAL ARROW T/p-fao.ao TOP OF PAVEMENT T C-IOaaO TOP OF CURB T =laaa0 TOP OF WALL i c-I0000 TOP OF MOUND OR GRATE SYMBOL A, LINE LEGEND 0 POWER POLE 9 UGHT POUE —N GUY PARE ANCHOR 11w WATER VALVE 0 WATER METER m ELECTRICAL TRANSFORMER (Dam GAS METER OWN MANHOLE .am CLEANOUT 8PH FIRE HYDRANT Mm TELEPHONE PEDESTAL ■- AREA INLET Me JUNCTION BOX LGR. AREA LIGHT (GROUND) .Pf FIXED PIPE BOLLARD CURB INLET BUILDING SETBACK UNE - -- PROPERTY LINE -- EASEMENT LINE PUE. PUBLIC UTILITY EASEMENT 'A M,H. ►/ I u IHL icp ry�r of F.X �� Dw�i 2'%12' INI STY.-295.09' \ \, WHEELER SUBDIVISION, PHASE BLIII MK I LOT IR / J8Y RCPJ (0. ME 3490, PACEE260)\ \ / M.H.28, lB li � 41 291 -�® 2911 U M1W� RI INLET q9u UPF1tl 80) � F/gxEl^zcz.zo' / / \ N PLAN NORTH 1 � 0 t0 4f \� \ 91 \ CURVE DATA, DATARVJATRVE DATA: It R-656.00' \ D=62' 12' 19' Ol 2W8' HBEARSW BEAS 14' 19' Oi" \ G 193z1 \ - `\ jo 1 O Y ' 1 M.H. i� �— T/G-M,71V CY 1 �i EXISTNO C xEYSTONE WALL a W-237 eo' \1 35,5 L.F, OF B' WADE CONCRETE PILOT 1 _ T/W-TEO� pOCL-2ggm.0' E A L Ei VINO I ` WAIL -OUTLET (01) gg E i N =2BB79' S ) I ��T/W-28].00' ` T/W-2gT.g0• ' p22L=28e.sa' POOL_288,g0• / 33.90 L.F. OF JB f ` - A ADS Metz) siORM 1 / / / • I �� / 1 A% , VERSA-WAL ON I / \\N J l /l STOB! /% I / cu9e PAST L BEFORB YOU DIG I /.I J / F N)1289,85' MAS 01S GU. SY]IO' -ow W5 J /IIIIaeR0.o I 0PNWAY I. PER INS (s / �/ 0.1-OB-IOPP) I/Y I.R RD- 16 ELECRIICALELUTIRICAL LECHSCVT O It2nrxnn�0 —_- _FIF, _- - - - ---- --_^ N 45'2B 30W r440.23' N/2' :.R. Ig- PIPE /kERR CAP 8CO"UlE XEAOWALL k RNONO FA(W)-287 0' ONE UNCOUN PLACE BLM{ 1, LOT I CALIEO: C-47 ACRES (VOLUME 0% PACE 178) I /LOT 1 / CALLO: 0.10 ACRES TWO UNCOLN PLACE ( (VSUNIE 228, PACE 329) I I 2A4 SMMJ EEMFR 3G1 24'I NMI'J MTE I UESCPoPNON I REVIEW ONLY NOT FOR CONSTRUCTION 1013/11 PRELIMINARY THIS DOCUMENT IS RELEASED FOR ME PURPOSE OF INTERIM REVIEW UNDER ME AUTHORITY OF WON A METCALF, P.E. / NO. 80583, ON OCTOBER 3, 2011 IT IS NOT TO BE USED FOR CONSTRUCTION, BIDDING I OR PERMIT PURPOSES II z U a C3 z Z Q 0 z z a aU' I BEfi at ON PH: PH. RIf I ae I BR" CHE REl I I � XX z�F FEZ z�F wz �La w1' z if)O U - U ad o � SURE floc RME CONSULTING ENGINEERS CLIENT NO. PROJECT NO. 197 — 0423 SHEET Ij OF 8 HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by {enter your company name here} Page 1 Pond P1: Pond 1 Inflow Area = 16.050 ac, Inflow Depth = 0.26" for 2-Year event Inflow = 16.65 cfs @ 0.17 hrs, Volume= 0.347 of Outflow = 5.43 cfs @ 0.39 hrs, Volume= 0.313 af, Atten= 67%, Lag= 13.3 min Primary = 5.43 cfs @ 0.39 hrs, Volume= 0.313 of Routing by Stor-Ind method, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs Peak Elev= 287.77'@ 0.39 hrs Surf.Area= 9,083 sf Storage= 9,138 cf Plug -Flow detention time=18.3 min calculated for 0.313 of (90% of inflow) Center -of -Mass det. time=17.0 min ( 30.4 - 13.3 ) #1 286.50' 33,023 cf Custom Stage Data Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 286.50 6,366 0 0 287.00 6,366 3,183 3,183 287.50 8,128 3,624 6,807 288.00 9,890 4,505 11,311 289.00 10,910 10,400 21,711 290.00 11,713 11,312 33,023 Device Routing Invert Outlet Devices #1 Primary 286.50' 1.00' x 1.00' Horiz. Orifice/Grate Limited to weir flow C= 0.600 Primary OutFlow Max=5.43 cfs @ 0.39 hrs HW=287.77'TW=284.28' (Fixed TW Elev= 284.28') t-1=0rifice/Grate (Orifice Controls 5.43 cfs @ 5.4 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 2-Year Duration=10 min, Inten=6.33 in/hr Prepared by {enter your company name here} Page 2 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/9/2011 w Pond P1: Pond 1 Hydrograph Inflow Area=16.050 ac Peak Elev=287.77' Storage=9,138 cf I[me tnours/ Pond P1: Pond 1 Stage -Area -Storage Storege (Cub101eel( Inflow Pnmary Surface Storage Section 5.0 STORM DRAINAGE SYSTEM HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, lnten=7.69 in/hr Prepared by {enter your company name here) Page 1 Pond P1: Pond 1 Inflow Area = 16.050 ac, Inflow Depth = 0.32" for 5-Year event Inflow = 20.25 cfs @ 0.17 hrs, Volume= 0.422 of Outflow = 5.97 cfs @ 0.40 hrs, Volume= 0.365 af, Atten= 71 %, Lag= 14.0 min Primary = 5.97 cfs @ 0.40 hrs, Volume= 0.365 of Routing by Stor-Ind method, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs Peak Elev= 288.03'@ 0.40 hrs Surf.Area= 9,926 sf Storage= 11,657 cf Plug -Flow detention time=19.6 min calculated for 0.362 of (86% of inflow) Center -of -Mass det. time=18.1 min ( 31.4 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 286.50' 33,023 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 286.50 6,366 0 0 287.00 6,366 3,183 3,183 287.50 8,128 3,624 6,807 288.00 9,890 4,505 11,311 289.00 10,910 10,400 21,711 290.00 11,713 11,312 33,023 Device Routing Invert Outlet Devices #1 Primary 286.50' 1.00' x 1.00' Horiz. Orifice/Grate Limited to weir flow C= 0.600 Primary OutFlow Max=5.96 cfs @ 0.40 hrs HW=288.03' TW=284.89' (Fixed TW Elev= 284.89') t-1=Orifice/Grate (Orifice Controls 5.96 cfs @ 6.0 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 5-Year Duration=10 min, lnten=7.69 in/hr Prepared by {enter your company name here} Page 2 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/9/2011 W Pond P1: Pond 1 Hvdroaraph Inflow Area=16.050 ac Peak Elev=288.03' Storage=11,657 cf IIIIIC IIIvul, Pond P1: Pond 1 Stage -Area -Storage Storage (cubic -feet) -- INlow — Primary Surface Storage HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Prepared by {enter your company name here} Page 1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/9/2011 Pond P1: Pond 1 Inflow Area = 16.050 ac, Inflow Depth = 0.35" for 10-Year event Inflow = 22.72 cfs @ 0.17 hrs, Volume= 0.474 of Outflow = 6.30 cfs @ 0.41 hrs, Volume= 0.394 af, Atten= 72%, Lag= 14.3 min Primary = 6.30 cfs @ 0.41 hrs, Volume= 0.394 of Routing by Stor-Ind method, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs Peak Elev= 288.21'@ 0.41 hrs Surf.Area= 10,108 sf Storage= 13,444 cf Plug -Flow detention time=20.4 min calculated for 0.394 of (83% of inflow) Center -of -Mass det. time=18.4 min ( 31.8 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 286,50' 33,023 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 286.50 6,366 0 0 287.00 6,366 3,183 3,183 287.50 8,128 3,624 6,807 288.00 9,890 4,505 11,311 289.00 10,910 10,400 21,711 290.00 11,713 11,312 33,023 Device Routing Invert Outlet Devices #1 Primary 286.50' 1.00' x 1.00' Horiz. Orifice/Grate Limited to weir flow C= 0.600 Primary OutFlow Max=6.30 cfs @ 0.41 hrs HW=288.21' TW=285.29' (Fixed TW Elev= 285.29') L1=Orifice/Grate (Orifice Controls 6.30 cfs @ 6.3 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 10-Year Duration=10 min, Inten=8.63 in/hr Prepared by {enter your company name here} Page 2 W Pond P1: Pond 1 Hydrograph Inflow Area=16.050 ac Peak Elev=288.21' Storage=13,444 cf rime (hours) Pond P1: Pond 1 Stage -Area -Storage Storage (wblc-feet) — tnaow Primary Surface Storage HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 in/hr Prepared by (enter your company name here} Page,1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/9/2011 Inflow Area = 16.050 ac, Inflow Depth = 0.40" for 25-Year event Inflow = 25.95 cfs @ 0.17 hrs, Volume= 0.541 of Outflow = 6.72 cfs @ 0.41 hrs, Volume= 0.428 af, Atten= 74%, Lag= 14.7 min Primary = 6.72 cfs @ 0.41 hrs, Volume= 0.428 of Routing by Stor-Ind method, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs Peak Elev= 288.45' @ 0.41 hrs Surf.Area= 10,344 sf Storage= 15,817 cf Plug -Flow detention time=21.1 min calculated for 0.428 of (79% of inflow) Center -of -Mass det. time=18.7 min (32.1 - 13.3) Volume Invert Avail.Storage Storage Description #1 286.50' 33,023 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 286.50 6,366 0 0 287.00 6,366 3,183 3,183 287.50 8,128 3,624 6,807 288.00 9,890 4,505 11,311 289.00 10,910 10,400 21,711 290.00 11,713 11,312 33,023 Device Routing Invert Outlet Devices #1 Primary 286.50' 1.00' x 1.00' Horiz. Orifice/Grate Limited to weir flow C= 0.600 Primary OutFlow Max=6.72 cfs @ 0.41 hrs HW=288.45' TW=285.29' (Fixed TW Elev= 285.29') L1=Orifice/Grate (Orifice Controls 6.72 cfs @ 6.7 fps) MDW Revised-Rational-090911 Prepared by {enter your company HvdrOCAD® 7.10 s/n 003394 © 2005 F HydroCAD - Proposed Conditions Pond Calculations - Pond 1 TX -Brazos County 25-Year Duration=10 min, Inten=9.86 Whir name here} Page 2 Pond P1: Pond 1 Hydrograph Inflow Area=16.050 ac Peak Elev=288.45' Storag e=15,817 cf Time (hours) Pond P1: Pond 1 Stage-AreaStorage Storage (cubic-teet) In—F. Primary Surface Storage HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here} Page 1 Pond P1: Pond 1 Inflow Area = 16.050 ac, Inflow Depth = 0.46" for 50-Year event Inflow = 29.34 cfs @ 0.17 hrs, Volume= 0.612 of Outflow = 7.12 cfs @ 0.42 hrs, Volume= 0.461 af, Atten= 76%, Lag= 15.0 min Primary = 7.12 cfs @ . 0.42 hrs, Volume= 0.461 of Routing by Stor-Ind method, Time Span= 0.00-1.00 hrs, dt= 0.01 hrs Peak Elev= 288.69'@ 0.42 hrs Surf.Area 10,591 sf Storage= 18,349 cf Plug -Flow detention time=21.5 min calculated for 0.456 of (75% of inflow) Center -of -Mass det. time=18.9 min (32.3 -13.3 ) Volume Invert Avail.Storage Storage Description #1 286.50' 33,023 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 286.50 6,366 0 0 287.00 6,366 3,183 3,183 287.50 8,128 3,624 6,807 288.00 9,890 4,505 11,311 289.00 10,910 10,400 21,711 290.00 11,713 11,312 33,023 Device Routing Invert Outlet Devices #1 Primary 286.50' 1.00' x 1.00' Horiz. Orifice/Grate Limited to weir flow C= 0.600 Primary OutFlow Max=7.12 cfs @ 0.42 hrs HW=288.69' TW=285.83' (Fixed TW Elev= 285.83') 'L1=Orifice/Grate (Orifice Controls 7.12 cfs @ 7.1 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Rev ised-Rational-090911 TX -Brazos County 50-Year Duration=10 min, Inten=11.15 in/hr Prepared by {enter your company name here} Page 2 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/9/2011 Pond P1: Pond 1 Hydrograph W- _ '8; Inflow Area=16.050 ac a- 24' Peak Elev=288.69' - I / \ Storage=18,349 cf 14 W Time (hours) Pond P1: Pond 1 Stage -Area -Storage Stm age (cubic-faet) — Inflow Primary Surface Storage HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 1 Pond PI: Pond 1 Inflow Area = 16.050 ac, Inflow Depth = 0.48" for 100-Year event Inflow = 30.63 cfs @ 0.17 hrs, Volume= 0.639 of Outflow = 7.27 cfs @ 0.42 hrs, Volume= 0.472 af, Atten= 76%, Lag= 15.1 min Primary = 7.27 cfs @ 0.42 hrs, Volume= 0.472 of Routing by Stor-Ind method, Time Span= O.QO-1.00 hrs, dt= 0.01 hrs Peak Elev= 288.78'@ 0.42 hrs Surf.Area= 10,685 sf Storage= 19,326 cf Plug -Flow detention time=21.7 min calculated for 0.467 of (73% of inflow) Center -of -Mass det. time=19.0 minx( 32.3 -'13.3 ) Volume Invert Avail.Storage Storage Description #1 286.50' 33,023 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 286.50 6,366 0 0 287.00 6,366 3,183 3,183 287.50 8,128 3,624 6,807 288.00 9,890 4,505 11,311 289.00 10,910 10,400 21,711 290.00 11,713 11,312 33,023 Device Routing Invert Outlet Devices #1 Primary 286.50' 1.00' x 1.00' Horiz. Orifice/Grate Limited to weir flow C= 0.600 Primary OutFlow Max=7.27 cfs @ 0.42 hrs HW=288.78' TW=286.40' (Fixed TW Elev= 286.40') t1=0rifice/Grate (Orifice Controls 7.27 cfs @ 7.3 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 MDW Revised-Rational-09091 TX -Brazos County 100-Year Duration=10 min, Inten=11.64 in/hr Prepared by {enter your company name here} Page 2 HydroCAD®? 10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 9/9/2011 Pond P1: Pond 1 Hydrograph Ingow — Primary Inflow Area=16.050 ac Peak Elev=288.78' Storage=19,326 cf Time (houre) Pond P1: Pond 1 Stage -Area -Storage SurfacelHorizontilMetted Area (sq-ft) Surface Storage Storage (cubic -feet) stmOutput WinStorm (STORM DRAIN DESIGN) PROJECT NAME 197 JOB NUMBER 0423 PROJECT DESCRIPTION : MDW Centre -System A DESIGN FREQUENCY 10 Years ANALYSYS FREQUENCY : 100 Years MEASUREMENT UNITS: ENGLISH OUTPUT FOR DESIGN FREQUENCY of: 10 Years ------------------------------------------- Runoff Computation for Design Frequency. Version 3.05, Jan. 25, 2002 Run @ 9/29/2011 1:38:27 PM ID C Value Area Tc Tc Used Intensity Supply Q Total Q (acre) (min) (min) (in/hr) (cfs) (cfs) ----------------------------------------------------------------------------- A-1 0.82 1.12 10.00 10.00 8.63 0.000 7.930 0.96 0.84 Pavement 0.4 0.28 Undeveloped A-2 0.746 0.89 10.00 10.00 8.63 0.000 5.733 0.96 0.55 Pavement 0.4 0.34 Undeveloped -3 0.68 0.24 10.00 10.00 8.63 0.000 1.409 0.96 0.12 Pavement 0.4 0.12 Undeveloped A-4 0.68 0.22 10.00 10.00 8.63 0.000 1.292 0.96 0.11 Pavement 0.4 0.11 Undeveloped A-5 0.55 13.45 35.00 35.00 4.50 0.000 33.267 ----------------------------------------------------------------------------- 0.55 13.45 Single family Cumulative Junction Discharge Computations Node Node Weighted Cumulat. Cumulat. Intens. User Additional Total I.D. Type C-Value Dr.Area Tc Supply Q Q in Node Disch. --------------------------------------------------------------------------------- (acres) (min) (in/hr) cfs) (cfs) (cfs) OUT1 CircMh 0.584 15.92 35.19 4.48 0.000 0.00 41.654 A-1 JnctBx 0.584 15.92 35.19 4.48 0.000 0.00 41.654 A-2 JnctBx 0.566 14.80 35.09 4.49 0.000 0.00 37.603 A-3 JnctBx 0.554 13.91 35.01 4.50 0.000 0.00 34.664 A-4 JnctBx 0.680 0.22 10.00 8.63 0.000 0.00 1.292 A-5 JnctBx 0.550 13.45 35.00 4.50 0.000 0.00 33.267 Page 1 stmOutput -unveyance Configuration Data Run# Node I.D. Flowline Elev. US DS US DS Shape # Span Rise Length Slope n_value (ft) (ft) (ft) (ft) (ft) M ---------------------------------------------------------------------------------- 1 A-1 OUT1 289.13 288.79 Circ 1 0.00 3.00 33.90 1.00 0.012 2 A-2 A-1 289.85 289.23 Circ 1 0.00 3.00 62.30 1.00 0.012 3 A-3 A-2 291.76 290.86 Circ 1 0.00 2.00 50.10 1.80 0.012 4 A-4 A-3 294.53 292.48 Circ 1 0.00 2.00 117.40 1.75 0.012 5 A-5 A-3 296.18 292.48 Circ 1 0.00 1.50 24.20 15.47 0.012 ---------------------------------------------------------------------------------- Conveyance Hydraulic Computations. Tailwater = 288.210 (ft) Hydraulic Gradeline Depth Velocity Junc Run# US Elev DS Elev Fr.Slope Unif. Actual Unif. Actual Q Cap Loss (ft) (ft) M (ft) (ft) (f/s) (f/s) (cfs) (cfs) (ft) ---------------------------------------------------------------------------------- 1* 290.76 290.42 0.332 1.63 1.63 10.62 10.62 41.65 72.37 0.000 2* 291.39 290.77 0.271 1.54 1.54 10.33 10.33 37.60 72.09 0.000 3* 293.53 292.63 2.000 1.77 1.77 11.81 11.81 34.66 32.85 0.000 4* 294.80 293.53 0.003 0.27 1.05 5.03 0.78 1.29 32.39 0.000 5* 297.19 293.53 8.544 0.96 1.05 27.75 25.29 33.27 44.77 0.000 -------------------------- OUTPUT FOR ANALYSYS FREQUENCY of: 100 Years --------------------------------------------- Runoff Computation for Analysis Frequency. ID C Value Area Tc Tc Used Intensity Supply Q Total Q ----------------------------------------------------------------------------- (acre) (min) (min) (in/hr) (cfs) (cfs) A-1 0.82 1.12 10.00 10.00 11.64 0.000 10.689 0.96 0.84 Pavement 0.4 0.28 Undeveloped A-2 0.746 0.89 10.00 10.00 11.64 0.000 7.728 0.96 0.55 Pavement 0.4 0.34 Undeveloped A-3 0.68 0.24 10.00 10.00 11.64 0.000 1.900 0.96 0.12 Pavement 0.4 0.12 Undeveloped A-4 0.68 0.22 10.00 10.00 11.64 0.000 1.741 0.96 0.11 Pavement Page 2 stmOutput 0.4 0.11 Undeveloped ;5 0.55 13.45 35.00 35.00 6.16 0.000 45.596 0.55 13.45 Single family ----------------------------------------------------------------------------- Cumulative Junction Discharge Computations Node Node Weighted Cumulat. Cumulat. Intens. User Additional Total I.D. Type C-Value Dr.Area Tc Supply Q Q in Node Disch. (acres) (min) (in/hr) cfs) (cfs) (cfs) --------------------------------------------------------------------------------- OUTl CircMh 0.584 15.92 35.16 6.15 0.000 0.00 57.119 A-1 JnctBx 0.584 15.92 35.16 6.15 0.000 0.00 57.119 A-2 JnctBx 0.566 14.80 35.07 6.16 0.000 0.00 51.556 A-3 JnctBx 0.554 13.91 35.01 6.16 0.000 0.00 47.512 A-4 JnctBx 0.680 0.22 10.00 11.64 0.000 0.00 1.741 A-5 --------------------------------------------------------------------------------- JnctBx 0.550 13.45 35.00 6.16 0.000 0.00 45.596 Conveyance Configuration Data Run# Node I.D. Flowline Elev. US DS US DS Shape # Span Rise Length Slope n_value (ft) (ft) (ft) (ft) (ft) M ----- -------------------------------------------------------------- A-1 OUT1 289.13 288.79 Circ 1 0.00 3.00 33.90 1.00 0.012 L A-2 A-1 289.85 289.23 Circ 1 0.00 3.00 62.30 1.00 0.012 3 A-3 A-2 291.76 290.86 Circ 1 0.00 2.00 50.10 1.80 0.012 4 A-4 A-3 294.53 292.48 Circ 1 0.00 2.00 117.40 1.75 0.012 5 A-5 A-3 296.18 292.48 Circ 1 0.00 1.50 24.20 15.47 0.012 ---------------------------------------------------------------------------------- Conveyance Hydraulic Computations. Tailwater = 288.780 (ft) Hydraulic Gradeline Depth Velocity Junc Run# US Elev DS Elev Fr.Slope Unif. Actual Unif. Actual Q Cap Loss (ft) (ft) M (ft) (ft) (f/s) (f/s) (cfs) (cfs) (ft) ---------------------------------------------------------------------------------- 1* 291.15 290.81 0.625 2.02 2.02 11.31 11.31 57.12 72.37 0.000 2* 291.74 291.15 0.509 1.88 1.92 11.09 10.82 51.56 72.09 0.000 3 295.62 292.84 3.757 2.00 2.00 15.12 15.12 47.51 32.85 0.000 4* 295.63 295.62 0.005 0.32 2.00 5.48 0.55 1.74 32.39 0.000 5 299.51 295.62 16.050 1.26 1.50 28.85 25.80 45.60 44.77 0.000 -----------------------------------END=----------------------_____________________ * Super critical flow. NORMAL TERMINATION OF WINSTORM. Page 3 stm0utput irning Messages for current project: Runoff Frequency of: 10 Years Tailwater set to uniform depth elevation = 290.42(ft) Run# 3 Insufficient capacity. Upstream hydraulic gradeline exceeds critical elevation at node Id= A-5 Runoff Frequency of: 100 Years Tailwater set to uniform depth elevation = 290.81(ft) Run# 3 Insufficient capacity. Run# 5 Insufficient capacity. Upstream hydraulic gradeline exceeds critical elevation at node Id= A-5 Page 4