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HomeMy WebLinkAboutDrainage report 4 Drainage Study FOR BALD PRAIRIE SUBDIVISION Lots 9R1 thru 9R11 College Station Brazos County, Texas September 1, 2010 Revision No. 1— October 4, 2010 OF • •• 1l • -AEON MA*LF A'1SS;ONAt "'In' Prepared For: Bryan Links, LLC 2020 Oakwood Trail College Station, TX 77845 Prepared By: RA/1E Consulting Engineers 7607 Eastmark Drive, Suite 252A <77840> P.O. Box 9253 College Station, TX 77845 Texas Firm Registration No. F -4695 ® RME No. 242 -0405 ) J Drainage Study BALD PRAIRIE SUBDIVISION Lots 9R1 thru 9R11 College Station Brazos County, Texas TABLE OF CONTENTS: PAGE 1.0 General Information 0 1.1 Scope of Report 0 1.2 Site and General Location 0 1.3 Description of Existing Conditions and Drainage Patterns 0 1.4 PIMA Information 0 2.0 Watersheds & Drainage Areas 0 2.1 Detention Facility Watersheds (Existing Conditions) 0 2.2 Detention Facility Watersheds (Proposed Conditions) 0 2.3 Sub - Drainage Basins for Storm Sewer Collection System 0 3.0 Hydrologic Modeling 0 3.1 Rational Formula and Methodology 0 3.2 Rainfall Intensity "I" 0 3.3 Weighted Runoff Coefficient "C" 0 3.4 Time of Concentration 0 3.5 Stormwater Runoff Quantities 0 4.0 Detention Facility & Routing 0 4.1 Detention Facility Criteria 0 4.2 Methodology 0 4.3 Detention Facility Configuration 0 4.4 Detention Facility Outlet Structures 0 4.5 Routing Results and Conclusions 0 5.0 Storm Drainage System. 0 5.1 Street Drainage 0 5.2 Storm Drain Inlets 0 5.3 Storm Drain Conduits 0 6.0 Certification 0 242 -0405 Drainage Report- Revl.docx Page - i LIST OF TABLES: PAGE Section 3.0 — Hydrologic Modeling Table #1: Ttt — Overland Sheet Flow 0 Table #2: T — Shallow and/or Concentrated Flow 0 Table #3: Tc Summary 0 Table #4: Drainage Basin Runoff Quantities 0 Section 4.0 — Detention Facility Routing Table #5: Detention Facility Routing 0 Section 5.0 — Storm Drainage System Table #6: Street Drainage Summary 0 Table #7: Curb Inlet Summary 0 Table #8: Storm Drainage Summary 0 242 -0405 Drainage Report- Revl.docx Page - ii ATTACHMENTS: Section 1.0 — General Information Replat Vicinity Map FIRM Panel Map Section 2.0 — Watersheds & Drainage Areas Lick 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 Conditions Drainage Calculations HydroCAD — Proposed Conditions Drainage Calculations Section 4.0 — Detention Facility & Routing GP -01: Paving, Grading & Drainage Plan HydroCAD — Proposed Conditions Pond Routing Calculations — Pond 1 Section 5.0 — Storm Drainage System Winstorm — Hydraulic Computations — Storm Drainage System "A" 242 -0405 Drainage Report- Revl.docx Page - iii Drainage Study — Revision No. 1 BALD PRAIRIE SUBDIVISION Lots 9R1 thru 9R11 College Station Brazos County, Texas 1.0 GENERAL INFORMATION 1.1 Scope of Report: This report addresses the existing conditions and proposed drainage improvements for the replat of Lots 9R1 thru 9R11 of the Bald Prairie Subdivision. This drainage study's scope will analyze the proposed detention facility design methods and proposed configurations, and the internal storm drainage system improvements designed for the development. All drainage system improvements (i.e. on -site detention facilities, storm sewer, etc...) will be designed to accommodate the anticipated proposed /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 replat development of Lot 9 of the Bald Prairie Subdivision consists of 2.93 acres of land consisting of eleven (11) residential lots with the construction of their associated improvements of paving, drainage, and utilities. The existing and proposed conditions of this development is depicted on the Replat which is provided in the "Attachment — Section 1.0" portion of this report. Lot 9 of the Bald Prairie Subdivision has access to Renee Lane along its southwest property line and access to Victoria Avenue along its northeast property line. Developments adjacent to these lots are all residential consisting of single- family residential (Edelweiss Gartens — Seection 6 & 7 and the remnant of the Bald Prairie Subdivision). A Vicinity Map, 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 2.93 acres of land, which contains the proposed development, is a moderately well sloping (approximately 2.0 %) substantially undeveloped site with natural overland 242 -0405 Drainage Report- Revl.docx Page -1 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 drainage that conveys runoff to a secondary drainage system of Lick Creek. This secondary system consist of a minor natural drainage channel that collects runoff drains to the northeast to an existing storm sewer system on Victoria Avenue. Runoff collected to this point is conveyed in a 48" diameter storm sewer pipe, and then is conveyed into the drainage and stormwater system of the Westfield Village. The headworks /subdivision discharge point of minor natural drainage channel is located at the subject property's northeast corner. The subject development area is primarily an unimproved area with the exception of some thick brush, weeds, and trees along the fence lines. Elevations range on the site from approximately 300' Mean Sea Level (MSL) to approximately 312' MSL. The Brazos County soil maps indicate that this area is comprised of Type C and D soils which consist of clays or silty clay /sand mixtures. Both pre -and post -runoff from the subject development will drain in a northeasterly direction through the proposed drainage structures or detention facility. Runoff is then discharged into the unnamed channel and storm sewer system of the Westfield Village development, via a storm sewer system crossing under Victoria Avenue. Eventually the unnamed tributary discharges into Lick Creek, thence to Carters Creek, thence to the Navasota River, thence to the Brazos River and ultimately to the Gulf of Mexico. 1.4 FEMA Information: A small portion of the subject development lies within mapped 100 -year floodplain as graphically depicted by the Federal Emergency Management Agency (FEMA) — Flood Insurance Rate Map (FIRM) Community/Panel number 480083 0201D, with an effective date of February 9, 2000. A portion of this FIRM Panel Map is located in the "Attachment — Section 1.0" section of the Drainage Report. 2.0 WATERSHEDS & DRAINAGE AREAS 2.1 Detention Facility Watersheds (Existing Conditions): As previously discussed, the subject development area is within the Bald Prairie Subdivision which is located within a watershed of an unnamed tributary that drains into the Lick Creek Watershed Area. An exhibit of this watershed is taken from the USDG manual with the subject area identified and is entitled as previously mentioned 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 existing runoff patterns and analysis and is described as follows. Drainage Area "X" — This drainage area is approximately 3.11 acres and will consist of the proposed development area and upstream contributing areas, at pre - development or existing conditions. At the downstream limit of this drainage area is the secondary 242 -0405 Drainage Report- Revl.docx Page -2 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4. 2010 drainage system Victoria Avenue (i.e. 48" RCP). Analysis of this drainage area will provide runoff characteristics for the appropriate portion of the subject development at its current existing conditions. This runoff data will be the "benchmark" data for the respective post - development area analysis so that increased runoff can be measured and appropriately detained. 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 "P" — This drainage area consists of an area within Drainage Area "X" and comprises of the same 3.11 acres of land. Proposed runoff conditions from this drainage area will be evaluated at the anticipated development conditions. The hydrologic data generated from this drainage area will drain into Pond 1, routed through the detention facility and discharged into the existing unnamed tributary of Lick Creek via the existing storm sewer system. Ultimately, routed flows, will be compared to the runoff values generated from Drainage Area "X"; 2.3 Subdrainage Basins for Storm Sewer Collection System: For analysis of the internal storm drainage system, the proposed Drainage Area "P" 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. The sub - drainage areas, per system, are briefly described below. • System A — The replatted portion of the Bald Prairie Subdivision and the upstream contributing drainage area. Some special considerations were made for sub - drainage areas within this system and are noted as follows: o DA Al — Runoff calculated from this drainage area drains to the proposed curb inlet located on the southeast side of the proposed "knuckle" off of Victoria Avenue; 3.0 HYDROLOGIC MODELING 3.1 Rational Formula and Methodology: 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 geometrics, 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: 242 -0405 Drainage Report- Revl.docx Page - 3 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers • Drainage Study — Rev. No. 1 October 4, 2010 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 - construction runoff coefficient "C" for the proposed development area is approximated to be 0.39. This coefficient was determined by calculating the weighted average of the runoff coefficient for the different surfaces types. Calculations for the coefficient are as follows: Drainage Area "X" Runoff Coefficient "CwTD ": 1.03 Acres — Undeveloped (Pasture Areas) -* "C" = 0.35; 2.08 Acres — Undeveloped (Woodland Areas) 4 "C" = 0.41; Pre - construction runoff coefficient 4 "CwTD" (0.35 *1.03)/3.11 + (0.41 *2.08) /3.11 "CwTD" = 0.39 The post - construction runoff coefficient "C" for the proposed development area is approximated to be 0.58. This coefficient was determined by calculating the weighted average of the runoff coefficient for the different surfaces types. Calculations for the coefficient are as follows: Drainage Area "P" Runoff Coefficient "CwTD ": 1.03 Acres — Asphalt Pavement, Roofs, Patio & Other Impervious - "C" =0.95 2.08 Acres — Yards (Fair Condition) - "C" =0.40 Post - construction runoff coefficient 4 "CwTD" (0.95* 1.03)/3.11 + (0.40 *2.08)/3.11 4 "C = 0.58 242 -0405 Drainage Report- Revl.docx Page -4 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4. 2010 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, T = {0.007 (n L) ° ' 8 } where, T, = 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 = i -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) Shallow Concentrated Flow, T = D /(60V) where, T = 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 — "T Overland Sheet Flow" and Table #2 — "T 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 Tc's for each sub - drainage basin where then computed and are summarized below in Table #3 — "Tc 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 -year) (S) (Tc) X 0.24 110 11.0 0.0075 0.205 P 0.24 110 11.0 0.0075 0.205 242 -0405 Drainage Report- Revl.docx Page - 5 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 TABLE #2 Tt2 - Shallow and /or Concentrated Flow Shallow (Unpaved) Shallow (Paved) Flow Average Flow Average Drainage Distance Velocity Distance Velocity Time Area I.D. (D1) (VI) (D2) (V2) (Tc) X 389 2.0 0 0.0 3.24 P 465 3.1 0 0.0 2.50 1) Unpaved Shallow Flow average velocities were estimated using the following equation V = 16.135 *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 *S where, V =fps S = average slope Assumptions — Manning's N = 0.025 & Hydraulic radius = 0.2 ft TABLE #3 Tc SUMMARY Combined Drainage Overland Channel Flow Te Area I.D. Flow Time Time (min) X 0.205 3.24 15.5 P 0.205 2.50 14.8 1) The minimum Tc utilized will be ten (10) minutes; 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 Conditions Drainage Calculations and HydroCAD- 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. 242 -0405 Drainage Report -Rev 1.docx Page - 6 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 TABLE #4 DRAINAGE BASIN RUNOFF QUANTITIES Drainage Drainage Rainfall Area Area Event (X) (P) (yr) (cfs) (cfs) 2 6.15 9.45 5 7.56 11.60 10 8.54 13.09 25 9.78 14.98 50 11.08 16.97 100 11.56 17.70 Runoff values generated from the smaller sub - drainage areas, for purposes of modeling the proposed storm sewer system and street drainage, are not summarized below 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 Hydrograph Ultimate Hydrograph 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. 242 -0405 Drainage Report- Revl.docx Page -7 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 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 3.6 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" discharges. For this project, at proposed development conditions, the discharge values shall be such that the routed flows through Pond 1 (from Drainage Area "P "), are equal to or less than the peak discharge rates of Drainage Area "X". 4.3 Detention Facility Configuration: The detention facility for the subject development will consist of one pond. With the construction of this detention facility, called Pond 1, an outlet structure will be installed to detain/meter increased runoff from Drainage Area "P ". The proposed GP -01: Paving, Grading & Drainage Plan for this project more fully depicts these improvements and is 242 -0405 Drainage Report- Revl.docx Page - 8 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 contained under the "Attachment - Section 4.0" portion of this report. The detention facility is briefly summarized below: Pond 1: Runoff from Drainage Area "P" is conveyed by means of overland flow. Pond 1 is "dry" pond with a bottom elevation of 300.75' and a maximum berm or ponding elevation of 304.10'. Sideslopes of the detention pond will be vegetative with 4H:1 V sideslopes. The pond will be constructed with a concrete low -flow pilot channel and all earthen areas will have a bottom slope at a 2.00 %. Runoff routed through Pond 1 is metered through an irregular shaped weir and this is discharged into the storm drainage system of the proposed development; 4.4 Detention Facility Outlet Structure: The detention facility outlet structure has been designed to accommodate and route collected stormwater runoff, from Drainage Area "P" so that during analyzed /routed rainfall events the post- development discharge rates are near or less than the "benchmark" discharge values generated from Drainage Area "X". These "benchmark" discharge values are illustrated in Table #6 contained in Section 3.6 of this report. The discharge structure of each detention pond will serve as the restricting or metering device, and are summarized below: Pond 1: Pond 1 discharge structure through an irregular shaped trapezoidal weir. This outlet weir structure will extend to a height of 303.60'. The irregular shaped weir will have the geometric shape as follows. Head = 0.0' - Width of 6 "; Head = 2.85' - Width of 12 "; The maximum berm height will extend also to an elevation of 304.10' which will provide 0.53' of freeboard above the maximum pool elevation occurring during the 100 -year rainfall event. Tailwater considerations for the outlet of Pond 1 were set at a free discharge condition. 4.5 Routing Results and Conclusions: Once the project's detention facility and outlet structure was determined, then the hydrograph for Drainage Basin "P" 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 I and its supporting data is contained the "Attachment - Section 4.0" section of this Drainage Report. As shown below in Table #5 - "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 below the "benchmark" discharges without overtopping the maximum berm elevation. 242 -0405 Drainage Report- Revl.docx Page - 9 Bald Prairie Subdivision - Replat of Lot 9 RME Consulting Engineers Drainage Study - Rev. No. 1 October 4. 2010 TABLE #5 DETENTION FACILITY ROUTING Routed Benchmark Diff. in Rainfall Storage Max. Discharge Discharge Discharge Max. Berm Event Volume Pool Elev Rate Rate Rate Elev. Freeboard (yr) (cu.ft.) (ft) (cfs) (cfs) (cfs) (ft) _ (ft) DETENTION POND 1 - PROPOSED CONDITIONS 2 4,480 302.73 5.85 6.15 -0.30 304.10 1.37 5 5,591 302.98 7.13 7.56 -0.43 304.10 1.12 10 6,363 303.13 8.02 8.54 -0.52 304.10 0.97 25 7,343 303.32 9.16 9.78 -0.62 304.10 0.78 50 8,371 303.50 10.36 11.08 -0.72 304.10 0.60 100 8,751 303.57 10.81 11.56 -0.75 304.10 _ 0.53 5.0 STORM DRAINAGE SYSTEM The "system criteria" listed below in the follow sub - sections are only the main highlights of the CoCS - USDG. The proposed development and drainage improvements are designed and analyzed in full accordance with the criteria outlined in this manual. 5.1 Street Drainage SYSTEM CRITERIA: 1. The maximum velocity of street flow shall not exceed 10 fps. At "T" street intersection the flow velocity will be checked on the stem of the "T ". The minimum velocity shall be maintained by keeping a gutter slope of 0.60% or greater; 2. The depth of flow shall be limited to the top of the curb for the design flow (10 -year rainfall event) and shall be contained within the right -of -way during the 100 -year rainfall event: a. Local Streets - The design storm in local streets shall be limited to the top of crown or the top of curb, whichever is less; b. Collector Streets - Design storm flow in collector streets shall be limited so that one 12 -foot wide area at the center of the street will remain clear of water; 3. Curb inlets shall be placed in a manner to ensure that the design storm flows are intercepted along street legs in advance of the curb returns. For intersection types of Collector to Local, the curb inlets shall be placed along the local legs. For intersection types of Local to Local it is preferred that the curb inlets be located along two legs. METHODOLGY & CONCLUSIONS: The hydraulic analysis, for street drainage with straight crowns, and corresponding results were determined by using the following equation for triangular channels. Corresponding flows for the studied locations were extracted from 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). 242 -0405 Drainage Report- Revl.docx Page -10 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 Flow Depth, Y = {Qn / [(0.56z *S where, Y = depth of flow (ft); Q = gutter discharge (cubic feet per second); z = reciprocal of the crown slope (ft /ft); S = street or gutter slope (ft/ft); n = Manning's roughness coefficient (typically 0.018); Flow Velocity, V = [(1.49 =n) * (R * S where, V = velocity of flow (fps); R = hydraulic radius (cross- sectional area/wetted perimeter); S = street or gutter slope (ft /ft); n = Manning's roughness coefficient (typically 0.014); Street drainage depths, for the both the design storm and 100 -year rainfall event, are summarized below in Table #6 — "Street Drainage Summary". TABLE #6 STREET DRAINAGE SUMMARY 10 -YR 100 -YR 10 -YR 100 -YR Gutter Flow Flow 10 -YR 100 -YR RunoffQ RunoffQ Slope Depth Depth Velocity Velocity Location (cfs) (cfs) (ft/ft) (ft) (ft) (fps) (fps) Curb Inlet "Al" 3.575 4.819 0.006 0.27 0.30 1.93 2.08 Street Drainage Notes: 1. Design calculations are with a n =0.018 and z =33.3 (cross -slope of 3.00 %); 2. Runoff rates illustrated are from the Winstorm program. These Q's are the total runoff values being conveyed in the gutter immediately upstream of the identified inlet. For curb inlets at grade, the total runoff is input in lieu of that inlet's intercept capacity; 3. The maximum allowable depth, during the design storm, for all streets is 0.42'; 5.2 Storm Drain Inlets SYSTEM CRITERIA: 1. All curb inlets within this project are specified as recessed curb inlets with gutter depressions. Curb inlets that are located on streets with less than a 1% longitudinal slope shall be analyzed as curb inlets at sumps; 2. At any developments scenario and analyzed rainfall event, up to the 100 -year frequency, the ponding depth at the inlet shall not exceed 24 "; METHODOLGY & CONCLUSIONS: The hydraulic analysis, for curb inlet sizing, and corresponding results were determined by using the following equation from the USDG, Table C -8 of Appendix C. Corresponding flows for the studied locations were extracted from 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). 242 -0405 Drainage Report- Revl.docx Page -11 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 Required Curb Length (on grade), L = Kc Q o.42 S o.3 (1 _ (nS ° ' 6 where, S S +(E L = calculated curb length requirement (ft); S = Substitution for S, which is the cross slope of the road (ft /ft); K = 0.6 (coefficient); S = street or gutter slope (ft /ft); a = gutter depression depth (ft); W = width of gutter depression (ft); E = ratio of frontal flow to total gutter flow (estimated at 0.50); Required Curb Length (at sag), L = Q / (3.0 *y'' where, L = calculated curb length requirement (ft); Q = gutter discharge (cubic feet per second); y = total depth of water or head on the inlet (ft); Curb inlet sizing, for the both the design storm and 100 -year rainfall event, are summarized below in Table #7 — "Curb Inlet Summary". TABLE #7 CURB INLET SUMMARY 10 - 100 -YR 10 -YR 100 -YR Gutter Required Required Provided Curb Inlet Runoff Q Runoff Q Slope Length Length Length Location - Curb Inlet I.D. Type (cfs) (cfs) (ft/ft) (ft) (ft) (ft) Curb Inlet "A1" Sag 3.575 4.819 0.006 3.37 4.54 5 Curb Inlet Notes: 1. Design calculations are with a standard gutter depression depth (a) of 0.33' and standard depression width (W) of 2'; 2. Design calculations are with a n =0.018 and a standard cross - sectional slope of 3.0% (0.03 ft/ft); 3. Curb inlets analyzed at sags will utilize the depth (y) of 6" unless otherwise noted; 4. Curb inlets at grade were allowed to be undersized so long as the downstream gutter section and ultimate receiving sag inlet could accommodate conveyed flows. 5.3 Storm Drain Conduits SYSTEM CRITERIA: 1. Storm drainage systems are designed to convey the design storm and analyzed during the 100 -year rainfall event. A gravity over -flow route, contained within the right -of- way or public drainage easement, 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; 242 -0405 Drainage Report- Revl.docx Page -12 Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 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 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 12" below the respective curb 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, are summarized below in Table #8 — "Storm Drainage Summary". As illustrated in the Winstorm output data the discharge velocities for the 10 -year and 100 -year rainfall event are respectively 4.98 fps and 5.33 fps for System "A ". TABLE #8 STORM DRAINAGE SUMMARY Pipe Size US Top of US Node DS Node Diameter Velocity Capacity RunoffQ US HGL Curb Diff ID ID (in) (fps) (cfs) (cfs) (ft) Elev. (ft) (ft) SYSTEM "A" - DESIGN STORM (10 -YEAR) Al OUT 1 1 18 1 2.69 9.53 3.57 1 303.67 307.08 -3.41 SYSTEM "A" - ANALYZED STORM (100 -YEAR) Al OUT 1 I 18 I 3.63 9.53 4.82 I 304.00 307.08 -3.08 Storm Drainage System Notes: 1. All proposed storm sewer system outfalls are specified with velocity dissipaters at the headwall; 242 -0405 Drainage Report- Revl.docx Page -13 . Bald Prairie Subdivision — Replat of Lot 9 RME Consulting Engineers Drainage Study — Rev. No. 1 October 4, 2010 6.0 CERTIFICATION "This report for the drainage design of Bald Prairie Subdivision (Lots 9R1 thru 9R11) 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." OF T k. - •. • 1i1� _ 1 i *' ` S. , - * • e - Aao , • • 4 ∎F 83 Ames, t. t, • • FS /CNAL . E� � O Rabon Metcalf, P.E. State of Texas P.E. No. 88583 Texas Firm Registration No. F -4695 242 -0405 Drainage Report- Revl.docx Page -14 Section 1.0 GENERAL INFORMATION . 1 I 1 I. . 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The City of Bryan and The city of College Station make no expressed or in guarantee concerning the a:curacy of this informal, : ill ............. . x• O; ( ffll114 � Gy r C ITY OF COLLEGE STATION CITY OF BRYAN Y p � DISCLAIMER: This map is a product of the City of Bryan GIS Department developed with extensive cooperation between the City of Bryan, the City of College Station and Brazos County. All data. information, and maps are provided as is" without warranty or any 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 requestor 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.O.BOX 1000 * Bryan, TX 77805 http:// ims. bryantx. gov/ gis/ servlet/ com. esri .esrimap.Esrimap ?ServiceName= REGIONAL_... 8/31/2010 Section 2.0 WATERSHEDS & DRAINAGE AREAS Pir allP1■111 • • r ....._____ . 1 .:_.____,.. it p. 1 i -1----- 1 11. , . 45 6 , ." 6 ti i \ { X • -: ,.' �� ... c;'q; , _. 1 , /; \_ 1 / - w • r r.: ' ti. ` �1 7'�- � .f' { . fti �, t' 1, . `� •• - _ 1 ` '•. 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(V (IiSi \D m � > J \ � / _m / / vQ+zo / / 1'!N r� / r ri i nx m . \ a .. / c a° en n � 1 1 . ,1 ' \ / , v, x p m V / P 74 \ v ' 76 < n ., ~ / Age o k 1 . r' t7d C ' 2 gE z O a / ' / N w gm� > / / °z J M � ^ // / C") / t i ''-r o M cn / // 2 2 / I pp:a 2 ? g. / • it - 1 e ? rgizi ,, r ic) ''"' , / ; 1 A O Section 3.0 HYDROLOGIC MODELING _ - . r HydroCAD- Existing Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 2 - Year Duration =16 min, Inten =5.02 in /hr Prepared by {enter your company name here} Page 1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -X: Pre - Development "X" Runoff = 6.15 cfs @ 0.26 hrs, Volume= 0.201 af, Depth= 0.77" 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 =l6 min, Inten =5.02 in /hr Area (ac) C Description 3.110 0.39 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.5 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 6.15 cfs L -° Runoff' TX- Brazos County 2 -Year Duration =l6 min, 5- Inten =5.02 in /hr s z 4 Runoff Area =3.110 ac Runoff Volume =0.201 af LL 3. Runoff Depth = 0.77" Tc =15.5 min 2- - -- C =0.39 1- 0 0 1 Time (hours) HydroCAD- Existing Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 5 - Year Duration =16 min, Inten =6.17 in /hr Prepared by {enter your company name here} Page 2 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -X: Pre - Development "X" Runoff = 7.56 cfs @ 0.26 hrs, Volume= 0.247 af, Depth= 0.95" 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 =16 min, Inten =6.17 in /hr Area (ac) C Description 3.110 0.39 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.5 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 8 1 7.56 cfs 1 [— Runoff TX- Brazos County 5 -Year Duration =l6 min, 6 Inten =6.17 in /hr 5- Runoff Area =3.110 ac Runoff Volume =0.247 af c 4- Runoff Depth = 0.95" 3- Tc =15.5 min C =0.39 o -. o Time (hours) HydroCAD- Existing Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 10 - Year Duration =16 min, Inten =6.97 in /hr Prepared by {enter your company name here} Page 3 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -X: Pre - Development "X" Runoff = 8.54 cfs @ 0.26 hrs, Volume= 0.279 af, Depth= 1.08" 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 =16 min, Inten =6.97 in /hr Area (ac) C Description 3.110 0.39 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.5 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 1 854 cfs I [- Runoff TX- Brazos County 10 -Year 7_ Duration =l6 min, Inten =6.97 in /hr 6. Runoff Area =3.110 ac 2. 5- Runoff Volume =0.279 af - a 4- Runoff Depth = 1.08" Tc =15.5 min C =0.39 2- 0 0 Time (hours) HydroCAD- Existing Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 25 - Year Duration =16 min, Inten =7.98 in /hr Prepared by {enter your company name here} Page 4 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -X: Pre - Development "X" Runoff = 9.78 cfs @ 0.26 hrs, Volume= 0.319 af, Depth= 1.23" 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 =16 min, Inten =7.98 in /hr Area (ac) C Description 3.110 0.39 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.5 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 10 9.78 cfs [ — Runoff' 9- TX- Brazos County 25 -Year 8 Duration =l6 min, 7 Inten =7.98 in /hr Runoff Area =3.110 ac 6 Runoff Volume =0.319 af 3 5 = Runoff Depth = 1.23" Tc =15.5 min C =0.39 1- 0 . 0 1 Time (hours) HydroCAD- Existing Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 50 - Year Duration =16 min, Inten =9.04 in /hr Prepared by {enter your company name here} Page 5 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA - X: Pre - Development "X" Runoff = 11.08 cfs @ 0.26 hrs, Volume= 0.362 af, Depth= 1.40" 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 50 -Year Duration =16 min, Inten =9.04 in /hr Area (ac) C Description 3.110 0.39 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.5 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 12- 11.08 Cfs I [ Runoff` 11- ,o- TX- Brazos County 50 -Year Duration =l6 min, 9- Inten =9.04 in /hr 8- Runoff Area =3.110 ac w 7- 6 Runoff Volume =0.362 af Runoff Depth= 1.40" Tc =15.5 min : i j C =0.39 - -- 2 0 . 0 1 Time (hours) HydroCAD- Existing Conditions Drainage Calculations Bald Prairie -TR20- 090110 TX- Brazos County 100 -Year Duration =16 min, Inten =9.43 in /hr Prepared by {enter your company name here} Page 6 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -X: Pre - Development "X" Runoff = 11.56 cfs @ 0.26 hrs, Volume= 0.377 af, Depth= 1.46" 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 100 -Year Duration =16 min, Inten =9.43 in /hr Area ac ( ) C Description 3.110 0.39 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.5 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 12= 11.56 cfs 1- [ Runoff "- TX- Brazos County 100 -Year 10 Duration =l6 min, 9 = Inten =9.43 in /hr $= Runoff Area =3.110 ac � Runoff Volume =0.377 of LL 6 - Runoff Depth = 1.46" 5_ Tc =15.5 min C =0.39 3 2- 1, 0- 0 1 Time (hours) HydroCAD- Proposed Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 2 - Year Duration =15 min, Inten =5.19 in /hr Prepared by {enter your company name here} Page 1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -P: Post - Development P Runoff = 9.45 cfs @ 0.25 hrs, Volume= 0.291 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 2 -Year Duration =15 min, Inten =5.19 in /hr Area (ac) C Description 3.110 0.58 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P 10 9.45 cfs — Runoff TX- Brazos County 2 -Year 8= Duration =l5 min, 7- Inten =5.19 in /hr Runoff Area =3.110 ac _ Runoff Volume =0.291 af o 5 _ u. _._ Runoff Depth = 1.12" 4- Tc =14.8 min C =0.58 2 0 - 0 1 Time (hours) HydroCAD- Proposed Conditions Drainage Calculations Bald Prairie -TR20- 090110 TX- Brazos County 5 -Year Duration =15 min, Inten =6.38 in /hr Prepared by {enter your company name here} Page 2 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -P: Post - Development P Runoff = 11.60 cfs @ 0.25 hrs, Volume= 0.358 af, Depth= 1.38" 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 =15 min, Inten =6.38 in /hr Area (ac) C Description 3.110 0.58 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P Hydrograph 12. 11.60 cfs ( [• , Runoff II TX- Brazos County 5 -Year ' °- Duration =l5 min, Inten =6.38 in /hr 8= Runoff Area =3.110 ac Runoff Volume =0.358 af o Runoff Depth = 1.38" Tc =14.8 min 4. - C =0.58 3- 2- 0 . 0 1 Time (hours) HydroCAD-Proposed Conditions Drainage Calculations 9 Bald Prairie - TR20 - 090110 TX Brazos County 10 - Year Duration =15 min, Inten =7.19 in /hr Prepared by {enter your company name here} Page 3 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -P: Post - Development P Runoff = 13.09 cfs @ 0.25 hrs, Volume= 0.404 af, Depth= 1.56" 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 10 -Year Duration =15 min, Inten =7.19 in /hr Area (ac) C Description 3.110 0.58 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P Hydrograph 14_ ( 13.09 cfs I [ Runoff 13- 12_ TX- Brazos County 10 -Year 11. Duration =l5 min, 10= Inten =7.19 in /hr Runoff Area =3.110 ac 8- Runoff Volume =0.404 af 3 7- Runoff Depth = 1.56" 6 5- Tc =14.8 min 4 C =0.58 3- - 2- 1- 0 0 1 Time (hours) HydroCAD- Proposed Conditions Drainage Calculations Bald Prairie -TR20- 090110 TX- Brazos County 25 -Year Duration =15 min, Inten =8.23 in /hr Prepared by {enter your company name here} Page 4 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -P: Post - Development P Runoff = 14.98 cfs @ 0.25 hrs, Volume= 0.462 af, Depth= 1.78" 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 =15 min, Inten =8.23 in /hr Area (ac) C Description 3.110 0.58 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P Hydrograph 16- 1 14.98 cfs I [ -- Runoff 1 15. 14= TX- Brazos County 25 -Year 13 = Duration =15 min, Inten =8.23 in /hr 10 Runoff Area =3.110 ac 9- Runoff Volume =0.462 af 3 g- o 7 Runoff Depth =1.78" 6- -- Tc =14.8 min C =0.58 4- 3 -- - 0 0 Time (hours) • HydroCAD- Proposed Conditions Drainage Calculations Bald Prairie - TR20 - 090110 TX Brazos County 50 - Year Duration =15 min, Inten =9.33 in /hr Prepared by {enter your company name here} Page 5 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -P: Post - Development P Runoff = 16.97 cfs @ 0.25 hrs, Volume= 0.523 af, Depth= 2.02" 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 =15 min, Inten =9.33 in /hr Area (ac) C Description 3.110 0.58 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P Hydrograph 19 _ 18= 118.97 cfs I l- Runoff` 17= 18- TX- Brazos County 50 -Year 15= 14= Duration =l5 min, 13= Inten =9.33 in /hr 12- Runoff Area = 3.110 ac 10= Runoff Volume =0.523 af o . : Runoff Depth= 2.02" 7 Tc =14.8 min s = C =0.58 4. 3_ 2= 1= 0 • 0 1 Time (hours) • Bald Prairie -TR20- 090110 TX- Brazos County 100 -Year Duration =15 min, Inten =9.73 in /hr Prepared by {enter your company name here} Page 6 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Subcatchment DA -P: Post - Development P Runoff = 17.70 cfs @ 0.25 hrs, Volume= 0.546 af, Depth= 2.11" 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 =15 min, Inten =9.73 in /hr Area (ac) C Description 3.110 0.58 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 14.8 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P Hydrograph 19 : Runoff 17.70 cfs I 18- 17 TX- Brazos County 100 - Year 16- 15_ Duration =l5 min, 14 = Inten =9.73 in /hr 13. ,2 Runoff Area =3.110 ac "= Runoff Volume =0.546 af LL s; Runoff Depth= 2.11" 8= Tc =14.8 min 7- 6- C =0.58 5- 4- 3. 2- -- 1. 0 . 0 1 Time (hours) II Section 4.0 DETENTION FACILITY & ROUTING 1 1 %R0 I I rm i., 1 I � a 32 €E2T2 '� i x cci`>A ip Dm O mm;;;.CO I 1 1 1 - -- 1 m zrlrz; 1 n< i �+ I O1 / \ J > 0 G L mx A 1 1 I�I o , A.,p �y 2 F- / RCy�c�$ < C gQ v�+�m 1 r i;i m o �n m r�jri m i n ^n5'� y m � Z I. 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N a t S o�' FOR THE mz y' z0.•c � � ��� 8 F `R §. g m f ',: I �_` s 8 x BALD PRAIRIE SUBDIVISION q sz >A O $ ° —� � -� 0 s m V yg Z� Ci ■ O C IE E 1 u LOTS 9R1 thr 9R11 8 "m �m o l m p a ° � XI z r. g z 9! m ili j (11 z M N - Z' w 3 PAVING, DRAINAGE & UTILITY IMPROVEMENTS z m+r1 A m M g Op- , ;0 Z m R p1A COLLEGE STATION, BRAZOS COUNTY, TX € iR HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 2 - Year Duration =15 min, Inten =5.19 in /hr Prepared by {enter your company name here} Page 1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 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 Reach 1R: Discharge Pipe Peak Depth =0.80' Max Vet =6.1 fps Inflow =5.85 cfs 0.280 af D= 18.0" n =0.013 L =20.0' S= 0.0100 '/' Capacity =10.50 cfs Outflow =5.85 cfs 0.280 af Pond P1: Pond 1 Peak EIev= 302.73' Storage =4,480 cf Inflow =9.45 cfs 0.291 af Outflow =5.85 cfs 0.280 af • HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 2 -Year Duration =15 min, Inten =5.19 in /hr Prepared by {enter your company name here} Page 2 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe [52] Hint: Inlet conditions not evaluated [81] Warning: Exceeded Pond P1 by 1.00' @ 0.00 hrs Inflow Area = 3.110 ac, Inflow Depth > 1.08" for 2 -Year event Inflow = 5.85 cfs @ 0.44 hrs, Volume= 0.280 af Outflow = 5.85 cfs @ 0.44 hrs, Volume= 0.280 af, Atten= 0 %, Lag= 0.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Max. Velocity= 6.1 fps, Min. Travel Time= 0.1 min Avg. Velocity = 5.0 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.80' @ 0.44 hrs Capacity at bank full= 10.50 cfs Inlet Invert= 301.75', Outlet Invert= 301.55' 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 20.0' Slope= 0.0100 '/' Reach 1R: Discharge Pipe Hydrograph 6- [ 5.85 cfs I Inflow Outflow flow Area =3.110 ac 5- weak Depth =0.80' ■ 4 - ax Vel =6.1 fps D= 18.0" 3_ n =0.013 \,_ =20.0' 2- S = 0.0 0 '/' Capacity =10.50 c 0 0 1 Time (hours) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 2 - Year Duration =15 min, Inten =5.19 in /hr Prepared by {enter your company name here} Page 3 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe to . 1 4, j� / Storage` s 1 L o r ' 0 5 10 15 20 25 30 35 HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 2 -Year Duration =15 min, Inten =5.19 in /hr Prepared by {enter your company name here} Page 4 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Inflow Area = 3.110 ac, Inflow Depth = 1.12" for 2 -Year event Inflow = 9.45 cfs @ 0.25 hrs, Volume= 0.291 af Outflow = 5.85 cfs @ 0.44 hrs, Volume= 0.280 af, Atten= 38 %, Lag= 11.2 min Primary = 5.85 cfs © 0.44 hrs, Volume= 0.280 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 302.73' @ 0.44 hrs Surf.Area= 4,368 sf Storage= 4,480 cf Plug -Flow detention time =11.2 min calculated for 0.280 af (96% of inflow) Center -of -Mass det. time= 10.4 min ( 30.2 - 19.8 ) Volume Invert Avail.Storage Storage Description #1 300.75' 11,413 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 300.75 0 0 0 302.00 2,900 1,813 1,813 303.00 4,900 3,900 5,713 304.00 6,500 5,700 11,413 Device Routing Invert Outlet Devices #1 Primary 300.75' Custom Weir /Orifice, C= 2.62 Head (feet) 0.00 2.85 Width (feet) 0.50 1.00 Primary OutFlow Max =5.85 cfs @ 0.44 hrs HW= 302.73' (Free Discharge) L1= Custom Weir /Orifice (Weir Controls 5.85 cfs @ 4.4 fps) • HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 2 - Year Duration =15 min, Inten =5.19 in /hr Prepared by {enter your company name here} Page 5 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 10- ( 9.45 cfs 1 — Inflow — Primary Inflow Area =3.110 ac 8 - Peak EIev= 302.73' 5.85cfs 1 Storage =4,480 cf LL 4- 1- 0 0 1 Time (hours) Pond P1: Pond 1 Stage - Area - Storage Surface /Horizontal/Wetted Area (sq -ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 — Surface 304 — Storage 303 m m c O d w 302 301 - Custom Stage Data 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 5 -Year Duration =15 min, Inten =6.38 in /hr Prepared by {enter your company name here} Page 6 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 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 Reach 1R: Discharge Pipe Peak Depth =0.91' Max Vel =6.4 fps Inflow =7.13 cfs 0.342 af D= 18.0" n =0.013 L =20.0' S= 0.0100 '/' Capacity =10.50 cfs Outflow =7.13 cfs 0.342 af Pond P1: Pond 1 Peak EIev= 302.98' Stora 9 a =5 591 cf Inflow =11.60 cfs 0.358 af Outflow =7.13 cfs 0.342 af • HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 5 - Year Duration =15 min, Inten =6.38 in /hr Prepared by {enter your company name here} Page 7 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe [52] Hint: Inlet conditions not evaluated [81] Warning: Exceeded Pond P1 by 1.00' @ 0.00 hrs Inflow Area = 3.110 ac, Inflow Depth > 1.32" for 5 -Year event Inflow = 7.13 cfs @ 0.44 hrs Volume= 0.342 of Outflow = 7.13 cfs @ 0.44 hrs, Volume= 0.342 af, Allen= 0 %, Lag= 0.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Max. Velocity= 6.4 fps, Min. Travel Time 0.1 min Avg. Velocity = 5.3 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.91' @ 0.44 hrs Capacity at bank full= 10.50 cfs Inlet Invert= 301.75', Outlet Invert= 301.55' 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 20.0' Slope= 0.0100 '1' Reach 1R: Discharge Pipe Hydrograph 7.13 cfs I Inflow -- Outflow 7- flow Area =3.110 ac eak Depth =0.91' 5- 1 . ax Vel =6.4 fps D= 18.0" 4- n =0.013 3 _ =20.0' 2= S =0.0 ' 0 '/' Capacity =10.50 c 0 Time (hours) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 5 -Year Duration =15 min, Inten =6.38 in /hr Prepared by {enter your company name here} Page 8 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe Stage - Storage storage 1 a 0 0 0 5 10 15 20 25 30 35 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 5 - Year Duration =15 min, Inten =6.38 in /hr Prepared by {enter your company name here} Page 9 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Inflow Area = 3.110 ac, Inflow Depth = 1.38" for 5 -Year event Inflow = 11.60 cfs @ 0.25 hrs, Volume= 0.358 af Outflow = 7.13 cfs @ 0.44 hrs, Volume= 0.342 af, Atten= 38 %, Lag= 11.4 min Primary = 7.13 cfs @ 0.44 hrs, Volume= 0.342 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 302.98' @ 0.44 hrs Surf.Area= 4,850 sf Storage= 5,591 cf Plug -Flow detention time =11.4 min calculated for 0.342 af (96% of inflow) Center -of -Mass det. time= 10.5 min ( 30.4 - 19.8 ) Volume Invert Avail.Storage Storage Description #1 300.75' 11,413 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 300.75 0 0 0 302.00 2,900 1,813 1,813 303.00 4,900 3,900 5,713 304.00 6,500 5,700 11,413 Device Routing Invert Outlet Devices #1 Primary 300.75' Custom Weir /Orifice, C= 2.62 Head (feet) 0.00 2.85 Width (feet) 0.50 1.00 Primary OutFlow Max =7.13 cfs @ 0.44 hrs HW= 302.98' (Free Discharge) L1= Custom Weir /Orifice (Weir Controls 7.13 cfs @ 4.6 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 5 -Year Duration =15 min, Inten =6.38 in /hr Prepared by {enter your company name here} Page 10 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Hydrograph 12- ( 11.60 cfs ( — Inflow I — Primary Inflow Area =3.110 ac Peak EIev= 302.98' 713 Storage=5 591 cf cfs u 7. 0 6- u. 5- 4- 3- - - 2- -- 0 0 1 Time (hours) Pond P1: Pond 1 Stage - Area - Storage Surface /Horizontal/Wetted Area (sq -ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 — Surface 304 _ Storage 303- m m 0 W m W • 302 - 301 - S Custom Stage Data 0 1,000 2 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 10 - Year Duration =15 min, Inten =7.19 in /hr Prepared by {enter your company name here} Page 11 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 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 Reach 1 R: Discharge Pipe Peak Depth =0.98' Max Vel =6.5 fps Inflow =8.02 cfs 0.385 af D= 18.0" n =0.013 L =20.0' S= 0.0100 '/' Capacity =10.50 cfs Outflow =8.02 cfs 0.385 af Pond P1: Pond 1 Peak EIev= 303.13' Storage =6,363 cf Inflow =13.09 cfs 0.404 af Outflow =8.02 cfs 0.385 af HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 10 - Year Duration =15 min, Inten =7.19 in /hr Prepared by {enter your company name here} Page 12 HydroCAD© 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe [52] Hint: Inlet conditions not evaluated [81] Warning: Exceeded Pond P1 by 1.00' @ 0.00 hrs Inflow Area = 3.110 ac, Inflow Depth > 1.49" for 10 -Year event Inflow = 8.02 cfs @ 0.44 hrs, Volume= 0.385 af Outflow = 8.02 cfs @ 0.44 hrs, Volume= 0.385 af, Atten= 0 %, Lag= 0.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Max. Velocity= 6.5 fps, Min. Travel Time= 0.1 min Avg. Velocity = 5.5 fps, Avg. Travel Time= 0.1 min Peak Depth= 0.98' @ 0.44 hrs Capacity at bank full= 10.50 cfs Inlet Invert= 301.75', Outlet Invert= 301.55' 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 20.0' Slope= 0.0100 '/' Reach 1R: Discharge Pipe Hydrograph 8.02 cfs I -° Inflow II 8- w- Outflow flow Area =3.110 ac • eak Depth =0.98' 6- ax Vet =6.5 fps 2 5 D= 18.0" LL 4 n =0.013 3- =20.0' S =0.0 ! 0 '/' 2. Capacity =10.50 c . 1- 0 0 1 Time (hours) • HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 10 - Year Duration =15 min, Inten =7.19 in /hr Prepared by {enter your company name here} Page 13 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe Stage - Storage / L - Storage II 1- m a 0 0 0 5 10 15 20 25 30 35 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 10 -Year Duration =15 min, Inten =7.19 in /hr Prepared by {enter your company name here} Page 14 HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Inflow Area = 3.110 ac, Inflow Depth = 1.56" for 10 -Year event Inflow = 13.09 cfs @ 0.25 hrs, Volume= 0.404 af Outflow = 8.02 cfs @ 0.44 hrs, Volume= 0.385 af, Atten= 39 %, Lag= 11.4 min Primary = 8.02 cfs @ 0.44 hrs, Volume= 0.385 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.13' @ 0.44 hrs Surf.Area= 5,108 sf Storage= 6,363 cf Plug -Flow detention time =11.6 min calculated for 0.385 af (95% of inflow) Center -of -Mass det. time= 10.6 min ( 30.4 - 19.8 ) Volume Invert Avail.Storage Storage Description #1 300.75' 11,413 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 300.75 0 0 0 302.00 2,900 1,813 1,813 303.00 4,900 3,900 5,713 304.00 6,500 5,700 11,413 Device Routing Invert Outlet Devices #1 Primary 300.75' Custom Weir /Orifice, C= 2.62 Head (feet) 0.00 2.85 Width (feet) 0.50 1.00 Primary OutFlow Max =8.02 cfs @ 0.44 hrs HW= 303.13' (Free Discharge) L1= Custom Weir /Orifice (Weir Controls 8.02 cfs @ 4.8 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 10 - Year Duration =15 min, Inten =7.19 in /hr Prepared by {enter your company name here} Page 15 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Hydrograph 14: 1 13.09 cfs 1 Inflow ` 13: Primary I 12= Inflow Area =3.110 ac 11- Peak Elev= 303.13' 10- Storage =6,363 cf 8.02 cfs g 8- c) 7 LL 6 3- 2- 0 \ %44N4N 0 1 Time (hours) Pond P1: Pond 1 Stage- Area - Storage Surface /Horizontal /Wetted Area (sq -ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 Surface 304 4 Storage 303 ✓ w 302 301- 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 25 -Year Duration =15 min, Inten =8.23 in /hr Prepared by {enter your company name here} Page 16 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 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 Reach 1R: Discharge Pipe Peak Depth =1.08' Max Vet =6.7 fps Inflow =9.16 cfs 0.439 af D= 18.0" n =0.013 L =20.0' S= 0.0100 '/' Capacity =10.50 cfs Outflow =9.16 cfs 0.439 af Pond P1: Pond 1 Peak EIev= 303.32' Storage =7,343 cf Inflow =14.98 cfs 0.462 af Outflow =9.16 cfs 0.439 af HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 25 - Year Duration =15 min, Inten =8.23 in /hr Prepared by {enter your company name here} Page 17 HydroCAD 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe [52] Hint: Inlet conditions not evaluated [81] Warning: Exceeded Pond P1 by 1.00' @ 0.00 hrs Inflow Area = 3.110 ac, Inflow Depth > 1.70" for 25 -Year event Inflow = 9.16 cfs @ 0.44 hrs, Volume= 0.439 af Outflow = 9.16 cfs @ 0.44 hrs, Volume= 0.439 af, Atten= 0 %, Lag= 0.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Max. Velocity= 6.7 fps, Min. Travel Time= 0.0 min Avg. Velocity = 5.6 fps, Avg. Travel Time= 0.1 min Peak Depth= 1.08' @ 0.44 hrs Capacity at bank full= 10.50 cfs Inlet Invert= 301.75', Outlet Invert= 301.55' 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 20.0' Slope= 0.0100 '1' Reach 1R: Discharge Pipe Hydrograph 10- 9.16 cfs Inflow II -- Outflow 9: flow Area =3.110 ac 8: eak Depth =1.08' ax Vet =6.7 fps 6- D= 18.0" g 5 n =0.013 LL 4-_ 4 =20.0' S = 0.0 '/' 2 Capacity =10.50 c 0 0 Time (hours) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 25 -Year Duration =15 min, Inten =8.23 in /hr Prepared by {enter your company name here} Page 18 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe L - Storage 1 m m r a m 0 0 5 10 15 20 25 30 35 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 25 - Year Duration =15 min, Inten =8.23 in /hr Prepared by {enter your company name here} Page 19 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Inflow Area = 3.110 ac, Inflow Depth = 1.78" for 25 -Year event Inflow = 14.98 cfs @ 0.25 hrs, Volume= 0.462 af Outflow = 9.16 cfs @ 0.44 hrs, Volume= 0.439 af, Atten= 39 %, Lag= 11.5 min Primary = 9.16 cfs @ 0.44 hrs, Volume= 0.439 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.32' @ 0.44 hrs Surf.Area= 5,406 sf Storage= 7,343 cf Plug -Flow detention time =11.6 min calculated for 0.435 af (94% of inflow) Center -of -Mass det. time= 10.7 min ( 30.5 - 19.8 ) Volume Invert Avail.Storage Storage Description #1 300.75' 11,413 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 300.75 0 0 0 302.00 2,900 1,813 1,813 303.00 4,900 3,900 5,713 304.00 6,500 5,700 11,413 Device Routing Invert Outlet Devices #1 Primary 300.75' Custom Weir /Orifice, C= 2.62 Head (feet) 0.00 2.85 Width (feet) 0.50 1.00 Primary OutFlow Max =9.16 cfs @ 0.44 hrs HW= 303.32' (Free Discharge) L1= Custom Weir /Orifice (Weir Controls 9.16 cfs @ 4.9 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 25 - Year Duration =15 min, Inten =8.23 in /hr Prepared by {enter your company name here} Page 20 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Hydrograph 16. - 14.98 cfs I Inflow ` 15- - Primary 1 14= - -- Inflow Area =3.110 ac 13= 12 - Peak Elev= 303.32' Stora a =7 343 cf 8 5- 3= 2. 1= 0 0 1 Time (hours) Pond P1: Pond 1 Stage - Area - Storage Surface /Horizontal/Wetted Area (sq -ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 Surface 304 -- Storage 303- m c 0 I g w 302- - 301 - ustom Stage Data 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 50 - Year Duration =15 min, Inten =9.33 in /hr Prepared by {enter your company name here} Page 21 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 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 Reach 1R: Discharge Pipe Peak Depth =1.21' Max Vet =6.8 fps Inflow =10.36 cfs 0.496 af D= 18.0" n =0.013 L =20.0' S= 0.0100 '1' Capacity =10.50 cfs Outflow =10.36 cfs 0.496 af Pond P1: Pond 1 Peak EIev= 303.50' Storage =8,371 cf Inflow =16.97 cfs 0.523 af Outflow =10.36 cfs 0.496 af HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 50 - Year Duration =15 min, Inten =9.33 in /hr Prepared by {enter your company name here} Page 22 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe [52] Hint: Inlet conditions not evaluated [81] Warning: Exceeded Pond P1 by 1.00' @ 0.00 hrs Inflow Area = 3.110 ac, Inflow Depth > 1.92" for 50 -Year event Inflow = 10.36 cfs @ 0.44 hrs, Volume= 0.496 af Outflow = 10.36 cfs @ 0.44 hrs, Volume= 0.496 af, Atten= 0 %, Lag= 0.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Max. Velocity= 6.8 fps, Min. Travel Time= 0.0 min Avg. Velocity = 5.8 fps, Avg. Travel Time= 0.1 min Peak Depth= 1.21' @ 0.44 hrs Capacity at bank full= 10.50 cfs Inlet Invert= 301.75', Outlet Invert= 301.55' 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 20.0' Slope= 0.0100 '1' Reach 1R: Discharge Pipe Hydrograph 11: 10.36 cfs Inflow - Outflow ' °= flow Area =3.110 ac 9. eak Depth =1.21' 8- ax VeI =6.8 fps = D= 18.0" 6- n =0.013 - a 5- 4 =20.0' S =0.0 '/' 2- Capacity =10.50 c 0 . 0 Time (hours) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 50 -Year Duration =15 min, Inten =9.33 in /hr Prepared by {enter your company name here} Page 23 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe Stage- Storage -- Storage 1 Q. p 0 5 10 15 20 25 30 35 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 50 -Year Duration =15 min, Inten =9.33 in /hr Prepared by {enter your company name here} Page 24 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Inflow Area = 3.110 ac, Inflow Depth = 2.02" for 50 -Year event Inflow = 16.97 cfs @ 0.25 hrs, Volume= 0.523 af Outflow = 10.36 cfs @ 0.44 hrs, Volume= 0.496 af, Atten= 39 %, Lag= 11.5 min Primary = 10.36 cfs @ 0.44 hrs, Volume= 0.496 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.50' @ 0.44 hrs Surf.Area= 5,703 sf Storage= 8,371 cf Plug -Flow detention time =11.8 min calculated for 0.496 af (95% of inflow) Center -of -Mass det. time= 10.7 min ( 30.6 - 19.8 ) Volume Invert Avail.Storage Storage Description #1 300.75' 11,413 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 300.75 0 0 0 302.00 2,900 1,813 1,813 303.00 4,900 3,900 5,713 304.00 6,500 5,700 11,413 Device Routing Invert Outlet Devices #1 Primary 300.75' Custom Weir /Orifice, C= 2.62 Head (feet) 0.00 2.85 Width (feet) 0.50 1.00 Primary OutFlow Max =10.36 cfs @ 0.44 hrs HW= 303.50' (Free Discharge) t-1= Custom Weir /Orifice (Weir Controls 10.36 cfs @ 5.1 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 50 - Year Duration =l5 min, Inten =9.33 in /hr Prepared by {enter your company name here} Page 25 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Hydrograph 19_ 18 _ 16.97 cfs I Inflow -•- 17= Primary - ,6= Inflow Area =3.110 ac 15= Peak Elev= 303.50' 13= 12_ Storage =8,371 cf 10.36 cfs 10= 0 9= 8= 7= 5= 4= 3= 1-. 0 0 1 Time (hours) Pond P1: Pond 1 Stage - Area - Storage Surface /Horizontal/Wetted Area (sq -ft) O 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 — Surface 304 i i i . i i i i i i i i — Storage 303- O 0 c 0 0 w 302 - 301- •,....,.... . O 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 100 - Year Duration =15 min, Inten =9.73 in /hr Prepared by {enter your company name here} Page 26 HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 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 Reach 1R: Discharge Pipe Peak Depth =1.27' Max VeI =6.8 fps Inflow =10.81 cfs 0.518 af D= 18.0" n=0.013 _ S=0.0100 Capacity=10.50 Outflow= 10.81 013 L 20.0' S 0.0100 '/ ' Capacity -10.50 cfs Outflow 10.81 cfs 0.517 af Pond P1: Pond 1 Peak EIev= 303.57' Storage =8,751 cf Inflow =17.70 cfs 0.546 af Outflow =10.81 cfs 0.518 af HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 100 - Year Duration =15 min, Inten =9.73 in /hr Prepared by {enter your company name here} Page 27 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe [52] Hint: Inlet conditions not evaluated [55] Hint: Peak inflow is 103% of Manning's capacity [81] Warning: Exceeded Pond P1 by 1.00' @ 0.00 hrs Inflow Area = 3.110 ac, Inflow Depth > 2.00" for 100 -Year event Inflow = 10.81 cfs @ 0.44 hrs, Volume= 0.518 af Outflow = 10.81 cfs @ 0.44 hrs, Volume= 0.517 af, Atten= 0 %, Lag= 0.1 min Routing by Stor- Ind +Trans method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Max. Velocity= 6.8 fps, Min. Travel Time= 0.0 min Avg. Velocity = 5.8 fps, Avg. Travel Time= 0.1 min Peak Depth= 1.27' @ 0.44 hrs Capacity at bank full= 10.50 cfs Inlet Invert= 301.75', Outlet Invert= 301.55' 18.0" Diameter Pipe, n= 0.013 Concrete pipe, straight & clean Length= 20.0' Slope= 0.0100 '/' Reach 1R: Discharge Pipe Hydrograph 12- 10.81 cfs I Inflow 11- Outflow 10= - - iflow Area =3.110 ac eak Depth =1.27 $_ I ax Vel =6.8 fps D =18.0 n =0.013 5_ =20.0' 4- 3_ ' • ' /' 2- Capacity =10.50 c 0 0 Time (hours) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 100 -Year Duration =15 min, Inten =9.73 in /hr Prepared by {enter your company name here} Page 28 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Reach 1R: Discharge Pipe Storage II 1 m a d 0 0 0 5 10 15 20 25 30 35 Storage (cubic -feet) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie - TR20 - 090110 TX Brazos County 100 - Year Duration =15 min, Inten =9.73 in /hr Prepared by {enter your company name here} Page 29 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Inflow Area = 3.110 ac, Inflow Depth = 2.11" for 100 -Year event Inflow = 17.70 cfs @ 0.25 hrs, Volume= 0.546 af Outflow = 10.81 cfs @ 0.44 hrs, Volume= 0.518 af, Atten= 39 %, Lag= 11.5 min Primary = 10.81 cfs @ 0.44 hrs, Volume= 0.518 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.57' @ 0.44 hrs Surf.Area= 5,808 sf Storage= 8,751 cf Plug -Flow detention time =11.7 min calculated for 0.512 af (94% of inflow) Center -of -Mass det. time= 10.8 min ( 30.6 - 19.8 ) Volume Invert Avail.Storage Storage Description #1 300.75' 11,413 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 300.75 0 0 0 302.00 2,900 1,813 1,813 303.00 4,900 3,900 5,713 304.00 6,500 5,700 11,413 Device Routing Invert Outlet Devices #1 Primary 300.75' Custom Weir /Orifice, C= 2.62 Head (feet) 0.00 2.85 Width (feet) 0.50 1.00 Primary OutFlow Max =10.81 cfs @ 0.44 hrs HW= 303.57' (Free Discharge) 4 ---1= Custom Weir /Orifice (Weir Controls 10.81 cfs @ 5.1 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Bald Prairie -TR20- 090110 TX- Brazos County 100 -Year Duration =15 min, Inten =9.73 in/hr Prepared by {enter your company name here} Page 30 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 10/4/2010 Pond P1: Pond 1 Hydrograph 19: I 17.70 Cfs I — Inflow 18= — Primary Inflow Area =3.110 ac 141 Peak EIev= 303.57' 13 12= Storage=8 751 cf 10.81 cfs 3 10? LL 8= 7- 3 1= 0 1 Time (hours) Pond P1: Pond 1 Stage - Area - Storage Surface /Horizontal/Wetted Area (sq -ft) 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 — Surface 304 . . . . . . , . . . � . , . . . . , � . . . . . . . . . . . . . . . . . . . . . . . . . . — Storage 303- m a c 0 R m w 302- 301 Custom Stage Data 0 1,000 2 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 Storage (cubic -feet) Section 5.0 STORM DRAINAGE SYSTEM P r , stmOutput.txt WinStorm (STORM DRAIN DESIGN) Version 3.05, Jan. 25, 2002 Run @ 10/4/2010 8:58:41 AM PROJECT NAME : 242 JOB NUMBER 0405 PROJECT DESCRIPTION : Bald Prairie - 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. ID C Value Area Tc Tc Used Intensity Supply Q Total Q (acre) (min) (min) (in /hr) (cfs) (cfs) A -1 0.6 0.69 10.00 10.00 8.63 0.000 3.575 Sag Inlets Configuration Data. Inlet Inlet Length/ Grate Left -Slope Right -Slope Gutter Depth Critic ID Type Perim. Area Long Trans Long Trans n DeprW Allowed Elev. (ft) (sf) (%) (%) (%) (%) (ft) (ft) (ft) A -1 Curb 5.00 n/a 0.75 3.00 0.75 3.00 0.014 2.00 0.50 307.08 Sag Inlets Computation Data. Inlet Inlet Length Grate Total Q Inlet Total Ponded Width ID Type Perim Area Capacity Head Left Right (ft) (ft) (sf) (cfs) (cfs) (ft) (ft) (ft) A -1 Curb 5.00 n/a n/a 3.575 6.993 0.320 6.97 6.97 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 0.600 0.69 10.00 8.63 0.000 0.00 3.575 A -1 Curb 0.600 0.69 10.00 8.63 0.000 0.00 3.575 Page 1 stmOutput.txt 4 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) (%) 1 A -1 OUT1 302.91 301.23 Circ 1 0.00 1.30 111.68 1.50 0.012 , Conveyance Hydraulic Computations. Tailwater = 303.130 (ft) Hydraulic Gradeline Depth Velocity Junc Run# US Elev DS Elev Fr.Slope Unif. Actual Unif. Actual Q Cap Loss (ft) (ft) (%) (ft) (ft) (f /s) (f /s) (cfs) (cfs) (ft) 1* 303.67 303.13 0.212 0.55 1.30 6.68 2.69 3.57 9.53 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 0.6 0.69 10.00 10.00 11.64 0.000 4.819 Sag Inlets Configuration Data. Inlet Inlet Length/ Grate Left -Slope Right -Slope Gutter Depth Critic ID Type Perim. Area Long Trans Long Trans n DeprW Allowed Elev. (ft) (sf) (%) (%) (%) (%) (ft) (ft) (ft) A -1 Curb 5.00 n/a 0.75 3.00 0.75 3.00 0.014 2.00 0.50 307.08 Sag Inlets Computation Data. Inlet Inlet Length Grate Total Q Inlet Total Ponded Width ID Type Perim Area Capacity Head Left Right (ft) (ft) (sf) (cfs) (cfs) (ft) (ft) (ft) Page 2 stmOutput.txt • A -1 Curb 5.00 n/a n/a 4.819 6.993 0.390 7.80 7.80 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 0.600 0.69 10.00 11.64 0.000 0.00 4.819 A -1 Curb 0.600 0.69 10.00 11.64 0.000 0.00 4.819 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) (%) 1 A -1 OUT1 302.91 301.23 Circ 1 0.00 1.30 111.68 1.50 0.012 Conveyance Hydraulic Computations. Tailwater = 303.570 (ft) Hydraulic Gradeline Depth Velocity Junc Run# US Elev DS Elev Fr.Slope Unif. Actual Unif. Actual Q Cap Loss (ft) (ft) (%) (ft) (ft) (f /s) (f /s) (cfs) (cfs) (ft) 1* 304.00 303.57 0.385 0.66 1.30 7.19 3.63 4.82 9.53 0.000 END * Super critical flow. NORMAL TERMINATION OF WINSTORM. Warning Messages for current project: Runoff Frequency of: 10 Years Runoff Frequency of: 100 Years I Page 3 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 2 — Project Administration Start (Page 2.1) Engineering and Design Professionals Information Engineering Firm Name and Address: Jurisdiction FV W Cot1oti.Tti4G- NUtNt✓ . City: Bryan - P 0 - col, c12SS ✓ College Station Lo t ( E t + o+.i t 7 X -7164 2 61/%11° Date of Submittal: ! Lead Eng� � ine rs Name and Contact Info.(phone, e-mail, fax): Other: - 'Tzh Go+v 4. t=. -NSCCt esI F 2. Co,r4. Supporting Engineering / Consulting Firm(s): Other contacts: N /Pt N lPt- Developer / Owner / Applicant Information Developer / Applicant Name and Address: Phone and e-mail: FAR -4 M.1 Ends , Lt_C 2.oz.o c5P+c -w o00 - Cvtat. Co wP -txB. S-rtr tt 4r-4 Z( 7'1 54'5 Property Owner(s) if not Developer / Applicant (& address): Phone and e-mail: Project Identification Development Name: �p p LA — gvAr t eel; Ne. Is subject property a site project, a single -phase subdivision, or part of a multi -phase subdivision? 6u4-xt -F— `Him Si. € tvi $ .1 If multi - phase, subject property is phase of Legal description of subject property (phase) or Project Area: (see Section 11, Paragraph B -3a) Pt.A o Q Loz 9 Ee LertS 9021 E11 a1 12. of 1 E 4. M S ot`S If subject property (phase) is second or later phase of a project, describe general status of all earlier phases. For most recent earlier phase Include submittal and review dates. N 1� General Location of Project Area, or subject property (phase): Q p M 1"1 u S cD P- F,As..'F L• 6(1_ In City Limits? Extraterritorial Jurisdiction (acreage): Bryan: acres. Bryan: College Station: College Station: Z - '3 acres. Acreage Outside ETJ: STORMWATER DESIGN GUIDELINES Page 3 of 26 APPENDIX. D: TECH. DESIGN SUMMARY SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 2 — Proiect Administration Continued (page 2.2) Project Identification (continued) Roadways abutting or within Project Area or Abutting tracts, platted land, or built subject property: developments: I V..-V. L•? F E Ctj: -t CaArs - IS NRC.. 14 k vr�*..su - e Named Regulatory Watercourse(s) & Watershed(s): Tributary Basin(s): be_ sWIr€n OF N\t - ►Fw L C- L Plat Information For Project or Subject Property (or Phase) Preliminary Plat File #: Final Plat File #: Date: Name: Status and VoIPg: If two plats, second name: File #: Status: Date: Zoning Information For Project or Subject Property (or Phase) Zoning Type: Existing or Proposed? Case Code: Case Date 12 Status: Zoning Type: Existing or Proposed? Case Code: Case Date Status: Stormwater Management Planning For Project or Subject Property (or Phase) Planning Conference(s) & Date(s): Participants: Preliminary Report Required? 1\30 Submittal Date Review Date Review Comments Addressed? Yes No In Writing? When? Compliance With Preliminary Drainage Report. Briefly describe (or attach documentation explaining) any deviation(s) from provisions of Preliminary Drainage Report, if any. NIAN STORMWATER DESIGN GUIDELINES Page 4 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 2 — Project Administration Continued (page 2.3) Coordination For Project or Subject Property (or Phase) Note: For any Coordination of stormwater matters indicated below, attach documentation describing and substantiating any agreements, understandings, contracts, or approvals. Coordination Dept. Contact: Date: Subject: With Other Departments of Jurisdiction City (Bryan or College Station) Coordination With Summarize need(s) & actions taken (include contacts & dates): Non jurisdiction City Needed? Yes No ✓ Coordination with Summarize need(s) & actions taken (include contacts & dates): Brazos County Needed? Yes No Coordination with Summarize need(s) & actions taken (include contacts & dates): TxDOT Needed?/ Yes No ✓ Coordination with Summarize need(s) & actions taken (include contacts & dates): TAMUS Needed? Yes No k/ Permits For Project or Subject Property (or Phase) As to stormwater management, are permits required for the proposed work from any of the entities listed below? If so, summarize status of efforts toward that objective in spaces below. Entity Permitted or Status of Actions (include dates) Approved ? US Army Crops of Engineers No / Yes US Environmental Protection Agency No / Yes Texas Commission on �H 2 _ 5.3-4 e-S Environmental Quality F S No Yes V' Brazos River SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Start (Page 3.1) Nature and Scope of Proposed Work Existing: Land proposed for development currently used, including extent of impervious cover? Q p -.t 'YNI'OtAll'*.KNS Site Redevelopment of one platted lot, or two or more adjoining platted Tots. Development Building on a single platted lot of undeveloped land. Project Building on two or more platted adjoining lots of undeveloped land. (select all Building on a single lot, or adjoining Tots, where proposed plat will not form applicable) a new street (but may include ROW dedication to existing streets). / Other (explain): Subdivision Construction of streets and utilities to serve one or more platted Tots. Development Construction of streets and utilities to serve one or more proposed lots on Project lands represented by pending plats. Site proiects: building use(s), approximate floor space, impervious cover ratio. Describe Subdivisions: number of lots by general type of use, linear feet of streets and Nature and drainage easements or ROW. Size of G,(�G - t�on1 o? ►�'F.� t.cs"L S Proposed Project Is any work planned on land that is not platted If yes, explain: or on and for which platting is not pending? ✓ No Yes FEMA Floodplains Is any part of subject property abutting a Named Regulatory Watercourse No ✓ Yes (Section II, Paragraph B1) or a tributary thereof? Is any part of subject property in floodplain No ✓ Yes Rate Map area of a FEMA - regulated watercourse? Encroachment(s) Encroachment purpose(s): Building site(s) Road crossing(s) into F000dplain areas planned? Utility crossing(s) Other (explain): No tZ Yes If floodplain areas not shown on Rate Maps, has work been done toward amending the FEMA- approved Flood Study to define allowable encroachments in proposed areas? Explain. STORMWATER DESIGN GUIDELINES Page 6 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Continued (Page 3.2) Hydrologic Attributes of Subject Property (or Phase) Has an earlier hydrologic analysis been done for larger area including subject property? Yes Reference the study (& date) here, and attach copy if not already in City files. Is the stormwater management plan for the property in substantial conformance with the earlier study? Yes No If not, explain how it differs. N _ If subject property is not part of multi -phase project, describe stormwater management ° v plan for the property in Part 4. If property is part of multi -phase project, provide overview of stormwater management plan for Project Area here. In Part 4 describe how plan for subject property will comply therewith. Do existing topographic features on subject property store or detain runoff? No ✓ Yes Describe them (include approximate size, volume, outfall, model, etc). A -5rn P AL 5 Po,sn Btv s Fr -.0 VZtVt -.z,o j�2 Tt CA rr.431' »-J t -"C\L.1"t`1 Any known drainage or flooding problems in areas near subject property? ✓ No Yes Identify: Based on location of study property in a watershed, is Type 1 Detention (flood control) needed? (see Table B -1 in Appendix B) ✓ Detention is required. Need must be evaluated. Detention not required. What decision has been reached? By whom? r 22)4: If the need for How was determination made? Type 1 Detention must be evaluated: g /e,S ) \'' NE.S ? * t N Gc t Cr - r - ro NE t (vti epo ore.. W Cra-- . 704 F L�PMF. 'f STORMWATER DESIGN GUIDELINES Page 7 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 3 - Property Characteristics Continued (Page 3.3) Hydrologic Attributes of Subject Property (or Phase) (continued) Does subject property straddle a Watershed or Basin divide? ✓ No Yes If yes, describe splits below. In Part 4 describe design concept for handling this. Watershed or Basin Larger acreage Lesser acreage Above - Project Areas(Section II, Paragraph B3 -a) / Does Project Area (project or phase) receive runoff from upland areas? ✓ No Yes Size(s) of area(s) in acres: 1) 2) 3) 4) Flow Characteristics (each instance) (overland sheet, shallow concentrated, recognizable concentrated section(s), small creek (non - regulatory), regulatory Watercourse or tributary); Flow determination: Outline hydrologic methods and assumptions: Does storm runoff drain from public easements or ROW onto or across subject property? No Yes If yes, describe facilities in easement or ROW: Are changes in runoff characteristics subject to change in future? Explain Conveyance Pathways (Section II, Paragraph C2) Must runoff from study property drain across lower properties before reaching a Regulatory Watercourse or tributary? No ✓ Yes Describe length and characteristics of each conveyance pathway(s). Include ownership of property(ies). FXVo rS 1-- a 95 2Lf ur- Q.2a2. VlC a °('► I nt ro _ Dap k , Ag 6-1,• vcrr\ oP- 1f \11i.-Sz F- I FAA N. v,1.t_Mx - STORMWATER DESIGN GUIDELINES Page 8 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Continued (Page 3.4) Hydrologic Attributes of Subject Property (or Phase) (continued) Conveyance Pathways (continued) / Do drainage If yes, for what part of length? 100 % Created by? /plat, or easements instrument. If instrument(s), describe their provisions. exist for any part of pathway(s)? No j/Yes Where runoff must cross lower properties, describe characteristics of abutting lower property(ies). (Existing watercourses? Easement or Consent aquired ?) Pathway SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Start (Page 4.1) Stormwater Management Concept Discharge(s) From Upland Area(s) If runoff is to be received from upland areas, what design drainage features will be used to accommodate it and insure it is not blocked by future development? Describe for each area, flow section, or discharge point. N1 Discharge(s) To Lower Property(ies) (Section II, Paragraph El) Does project include drainag eatures (existing or future) propose ecome public via platting? t/ No es Separate Instrument? No Yes Per Guidelines reference above, how will Establishing Easements (Scenario 1) runoff be discharged to neighboring property(ies)? r/ Pre - development Release (Scenario 2) Combination of the two Scenarios Scenario 1: If easements are proposed, describe where needed, and provide status of actions on each. (Attached Exhibit # Scenario 2: Provide general description of how release(s) will be managed to pre - development conditions (detention, sheet flow, partially concentrated, etc.). (Attached Exhibit # ) ` i ia441tc.).,t I tIvc. t Lt w tzk} ►Mw_ 1 r424 Combination: If combination is proposed, explain how discharge will differ from pre - development conditions at the property line for each area (or point) of release. If Scenario 2, or Combination are to be used, has proposed design been coordinated with owner(s) of receiving property(ies)? No Yes Explain and provide documentation. STORMWATER DESIGN GUIDELINES Page 10 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.2) Stormwater Management Concept (continued) Within Proiect Area Of Multi -Phase Project Identify gaining Basins or Watersheds and acres shifting: Will project result in shifting runoff between Basins or between What design and mitigation is used to compensate for increased runoff Watersheds? from gaining basin or watershed? / No Yes How will runoff from Project 1. With facility(ies) involving other development projects. Area be mitigated to pre- 2. Establishing features to serve overall Project Area. development conditions? Select any or all of 1, 2, 3. On phase (or site) project basis within Project Area. and /or 3, and explain below. 1. Shared facility (type & location of facility; design drainage area served; relationship to size of Project Area): (Attached Exhibit # ) 2 = - -/ - 'v -eR r ' . e A el # i'[ i E _ , ' I I Ifs l` I It I j I 9 i6 I' i i 1 3 ! : s i 16 1 II 111 I I1ij 1, 'i ° it 9 i j* j 1( i i1 i li ! 1 EIt !! r r ' i i 1; I'{ 1 111 is i 3 11 3 iii, e h 11 i I 1 E 'I hi II , 1' j' l ! k 111 „4: i I 1 I 1 ! I 11 'Ii 11 It 1 11 111 j II f ' "l' I; I hi I i 1t F I= l I , .1 ii i s i ii[. Ifl I i11 i !� 1 HIJ i �i EJ HI 11 1 j hi i_' 1 1i ! gg Id ' i SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.3) Stormwater Management Concept (continued) Within Proiect Area Of Multi -Phase Project (continued) Will Project Area include bridge(s) or culvert(s)? (continued)/ Yes Identify type and general size and In which phase (s). 9 s P () If detention /retention serves (will serve) overall Project Area, describe how it relates to subject phase or site project (physical location, conveyance pathway(s), construction sequence): Within Or Serving Subject Property (Phase, or Site) If property part of larger Project Area, is desigryin substantial conformance with earlier analysis and report for larger area? Yes ✓ No, then summarize the difference(s): Identify whether each of the types of drainage features listed below are included, extent of use, and general characteristics. Typical shape? Surfaces? c•- .10 in Steepest side slopes: Usual front slopes: Usual back slopes: m >- f Flow line slopes: least Typical distance from travelway: • o typical greatest (Attached Exhibit # ) �, z ° Are longitudinal culvert ends in compliance with B -CS Standard Specifications? �' Yes No, then explain: At intgrsections or otherwise, do valley gutters cross arterial or collector streets? } i/ No Yes If yes explain: U \ c , Are valley gutters proposed to cross any street away from an intersection? Wi z° No ✓ Yes Explain: (number of locations ?) 2 • co STORMWATER DESIGN GUIDELINES Page 12 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.4) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Gutter line slopes: Least 0. &SX Usual 1 - o O Greatest 1 -i SX Are inlets recessed on arterial and collector streets? Yes No If "no ", identify where and why. N* Will inlets capture 10 -year desigp stormflow to prevent flooding of intersections (arterial with arterial or collector)? ✓ Yes No If no, explain where and why not. v 0) = Will inlet size and placement prevent exceeding, Ilowable water spread for 10 -year design storm throughout site (or phase)? 1 Yes No If no, explain. rn C 12 t0 5 Sao curves: Are inlets placed at low points? 1, Yes No Are inlets and . conduit sized to prevent 100 -year stormflow from ponding at greater than 24 inches? r 0 ✓ Yes No Explain "no" answers. 3 cp N co Will 100 -yr stormflow be containe in combination of ROW and buried conduit on whole length of all streets? V Yes No If no, describe where and why. Do dgsigns for curb, gutter, and inlets comply with B -CS Technical Specifications? ✓ Yes No If not, describe difference(s) and attach justification. Are any 12 -inch laterals used? /No Yes Identify length(s) and where used. N y y Pipe runs between system Typical 1'Z Longest 12- a) access points (feet): N I Are junction boxes used at each bend? Yes No If not, explain where and why. •@ Z f•i/T I ...,0 Are downstream soffits at or below upstream soffits? Least amount that hydraulic n Yes I/ No If not, explain where and why: grade line is below gutter line (system - wide): STORMWATER DESIGN GUIDELINES Page 13 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 • SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.5) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Describe watercourse(s), or system(s) receiving system discharge(s) below (include design discharge velocity, and angle between converging flow lines). 0 co 1) Watercourse (or system), velocity, and angle? ' PFt S1tut4 � �tCtIrtT`f — ✓ • E. 0 E 2) Watercourse (or system), velocity, and angle? c 0 • o c � E i 3) Watercourse (or system), velocity, and angle? c O is o - 0 a E For each outfall above, what measures are taken to prevent erosion or scour of y receiving and all facilities at juncture? 1) D■SS PTO � t,oc�c s f Rt==.-1 t 3) Are swale(s) situated along property lines between properties? No Yes Number of instances: For each instance answer the following questions. Surface treatments (including low -flow flumes if any): iu v } Flow line slopes (minimum and maximum): m 0 - o Z Outfall characteristics for each (velocity, convergent angle, & end treatment). N N Will 100 -year design storm runoff be contained within easement(s) or platted drainage ROW in all instances? Yes No If "no" explain: STORMWATER DESIGN GUIDELINES Page 14 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.6) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Are roadside ditches used? No Yes If so, provide the following: Is 25 -year flow contained with 6 inches of freeboard throughout ? Yes No . • Are top of banks separated from road shoulders 2 feet or more? Yes No • Are all ditch sections trapezoidal and at least 1.5 feet deep? Yes No • For any "no" answers provide location(s) and explain: a If conduit is beneath a swale, provide the following information (each instance). Instance 1 Describe general location, approximate length: a) r Is 100 -year design flow contained in conduit/swale combination? Yes No ( If "no" explain: o m Space for 100 -year storm flow? ROW Easement Width \ c Swale Surface type, minimum Conduit Type and size, minimum and maximum ( c and maximum slopes: slopes, design storm: v a) us Inlets Describe how conduit is loaded (from streets /storm drains, inlets by type): c T c � c m o U c a o Access Describe how maintenance access is provided (to swale, into conduit): o V- fd o E N •S . a, Instance 2 Describe general location, approximate length: E m • Is 100 -year design flow contained in conduit/swale combination? Yes No o o If "no" explain: m a. E ai Space for 100 -year storm flow? ROW Easement Width o • a Swale Surface type, minimum Conduit Type and size, minimum and maximum to and maximum slopes: slopes, design storm: c m • y Inlets Describe how conduit is loaded (from streets /storm drains, inlets by type): � c 3 Access Describe how maintenance access is provided (to swale, into conduit): STORMWATER DESIGN GUIDELINES Page 15 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.7) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) If "yes" provide the following information for each instance: Instance 1 Describe general location, approximate length, surfacing: c 0. E W L of Is 100 -year design flow contained in swale? Yes No Is swale wholly c >. within drainage ROW? Yes No Explain "no" answers: Access Describe how maintenance access is provide: L o "= z 0 U I Instance 2 Describe general location, approximate length, surfacing: o E .c • m Is 100 -year design flow contained in swale? Yes No Is swale wholly a o within drainage ROW? Yes No Explain "no" answers: To vi • p '— re Access Describe how maintenance access is provided: U d Instance 3, 4, etc. If swales are used in more than two instances, attach sheet providing all above information for each instance. "New" channels: Will any area(s) of concentrated flow be channelized (deepened, widened, or straightened) or otherwise altered? No Yes If only slightly shaped, see "Swales" in this Part. If creating side banks, provide information below. cs- c Will design replicate natural channel? Yes No If "no ", for each instance 0 :4 describe section shape & area, flow line slope (min. & max.), surfaces, and 100 -year o w design flow, and amount of freeboard: O Instance 1: E I o Instance 2: a E z (0 = Instance 3: U STORMWATER DESIGN GUIDELINES Page 16 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.8) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Existing channels (small creeks): Are these used? No Yes If "yes" provide the information below. Will small creeks and their floodplains remain undisturbed? Yes No How many disturbance instances? Identify each planned location: For each location, describe length and general type of proposed improvement (including floodplain changes): For each location, describe section shape & area, flow line slope (min. & max.), surfaces, and 100 -year design flow. m Watercourses (and tributaries): Aside from fringe changes, are Regulatory • Watercourses proposed to be altered? No Yes Explain below. Submit full report describing proposed changes to Regulatory Watercourses. Address existing and proposed section size and shape, surfaces, alignment, flow line changes, > length affected, and capacity, and provide full documentation of analysis procedures a and data. Is full report submitted? Yes No If "no" explain: E All Proposed Channel Work: For all proposed channel work, provide information requested in next three boxes. If design is to replicate natural channel, identify location and length here, and describe design in Special Design section of this Part of Report. Will 100 -year flow be contained with one foot of freeboard? Yes No If not, identify location and explain: Are ROW / easements sized to contain channel and required maintenance space? Yes No If not, identify location(s) and explain: STORMWATER DESIGN GUIDELINES Page 17 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.9) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) How many facilities for subject property project? a-- For each provide info. below. For each dry-type facilitiy: Facility 1 Facility 2 Acres served & design volume + 10% 4.1 1 (e t s `f / 100-yr volume: free flow & plugged qgze,3 cac ei / Design discharge (10 yr & 25 yr) - 7 - 4 - 1(e 2C . b 3 Spillway crest at 100 -yr WSE? ✓ yes no yes no Berms 6 inches above plugged WSE? +r yes no yes no Explain any "no" answers: 0 0 \ For each facility what is 25 -yr design Q, and design of outlet structure? Facility 1: Z 5 -'T'3 c 0 Z Facility 2: I Do outlets and spillways discharge into a public facility in easement or ROW? Facility 1: V Yes No Facility 2: Yes No O If "no" explain: 0 0 n 2 a For each, what ip, velocity of 25 -yr design discharge at outlet? & at spillway? co • Facility 1: 3 1:: & 3.P '5 Facility 2: & 5 Are energy dissipation measures used? No Yes Describe type and u.. location: c 1 g : c 0 0 0 2 For each, is spillway surface treatment other than concrete? Yes or no, and describe: • Facility 1: C�vc.lL —7r� Facility 2: For each, what measures are taken to prevent erosion or scour at receiving facility? Facility 1: Ex/91 C'oNG2ATE, /7P2Jq/ Facility 2: If berms are used give heights, slopes and surface treatments of sides. Facility 1 : / - 7 5 ' @ qii = / v 5 t t PE. Facility 2: STORMWATER DESIGN GUIDELINES Page 18 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 , SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.10) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Do structures comply with B -CS Specifications? Yes or no, and explain if "no ": ca Facility 1; yr.s a) ii c Facility 2: o c c U N — o For additional facilities provide all same information on a separate sheet. Are parking areas to be used for detention? V No Yes What is maximum depth due to required design storm? Roadside Ditches: Will culverts serve access driveways at roadside ditches? No Yes . If "yes ", provide information in next two boxes. Will 25 -yr. flow pass without flowing over driveway in all cases? Yes No Without causing flowing or standing water on public roadway? Yes No Designs & materials comply with B -CS Technical Specifications? Yes No Explain any "no" answers: c- o) rn c o Are culverts parallel to public roadway alignment? Yes No Explain: U N CD } CO .. Creeks at Private Drives: Do private driveways, drives, or streets cross drainage . ways that serve Above - Project areas or are in public easements/ ROW? Z No Yes If "yes" provide information below. N I How many instances? Describe location and provide information below. • Location 1: U 2 Location 2: Location 3: For each location enter value for: 1 2 3 Design year passing without toping travelway? Water depth on travelway at 25 -year flow? Water depth on travelway at 100 -year flow? : ni Tr! ' S reS (le lncatio an safe formation on sep arate sheet. 11 i r 1 11 1 +s + �1+ lii 1 1: !; � I ) � 2t ; { f 1 1 i 1 i $ i 1 i t , , + , + t$+ di I t !3 III 1111 I i, f ! 1 :+ 'd +, H i , 444 i v :. i � l th - E 1 " 1 sl iiiili ift , # ,`! ' 1. , 1'i , 'i di I.I. iii SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.11) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Named Regulatory Watercourses (& Tributaries): Are culverts proposed on these facilities? No Yes, then provide full report documenting assumptions, criteria, analysis, computer programs, and study findings that support proposed design(s). Is report provided? Yes No If "no ", explain: - Arterial or Major Collector Streets: Will culverts serve these types of roadways? N No Yes How many instances? For each identify the 0 location and provide the information below. o 0 n Instance 1: ( y Instance 2: o Instance 3: c 0 O Yes or No for the 100 -year design flow: 1 2 3 ,o Headwater WSE 1 foot below lowest curb top? c E Spread of headwater within ROW or easement? rn N Is velocity limited per conditions (Table C -11)? • -13 E xplain any "no" answer(s): o c U 2 >. 0 0 v o 42 Minor Collector or Local Streets: Will culverts serve these types of streets? o m No Yes How many instances? for each identify the = v location and provide the information below: 0. Q) m °; Instance 1: a c Instance 2: u, o Instance 3: > • U c For each instance enter value, or "yes" / "no" for: 1 2 3 0 Design yr. headwater WSE 1 ft. below curb top? • . 0 100 -yr. max. depth at street crown 2 feet or less? E Product of velocity (fps) & depth at crown (ft) = ? 1 Is velocity limited per conditions (Table C -11)? Limit of down stream analysis (feet)? Explain any "no" answers: STORMWATER DESIGN GUIDELINES Page 20 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 Drainage Concept and Design Parameters Continued (Page 4.12) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) All Proposed Culverts: For all proposed culvert facilities (except driveway /roadside ditch intersects) provide information requested in next eight boxes. Do culverts and travelways intersect at 90 degrees? Yes No If not, - identify location(s) and intersect angle(s), and justify the design(s): Does drainage way alignment change within or near limits of culvert and surfaced approaches thereto? No Yes If "yes" identify Iocation(s), describe change(s), and justification: Are flumes or conduit to discharge into culvert barrel(s)? No Yes If yes, identify location(s) and provide justification: Are flumes or conduit to discharge into or near surfaced approaches to culvert ends? No Yes If "yes" identify Iocation(s), describe outfall design treatment(s): c 0 0 Is scour /erosion protection provided to ensure long term stability of culvert structural 0 components, and surfacing at culvert ends? Yes No If "no" Identify locations and provide justification(s): Will 100 -yr flow and spread of backwater be fully contained in street ROW, and /or drainage easements/ ROW? Yes No if not, why not? Do appreciable hydraulic effects of any culvert extend downstream or upstream to neighboring land(s) not encompassed in subject property? No Yes If "yes" describe Iocation(s) and mitigation measures: Are all culvert designs and materials in compliance with B -CS Tech. Specifications? Yes No If not, explain in Special Design Section of this Part. STORMWATER DESIGN GUIDELINES Page 21 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.13) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Is a bridge included in plans for subject property project? /No Yes If "yes" provide the following information. Name(s) and functional classification of the roadway(s)? What drainage way(s) is to be crossed? u) rn a m A full report supporting all aspects of the proposed bridge(s) (structural, geotechnical, hydrologic, and hydraulic factors) must accompany this summary report. Is the report provided? Yes No If "no" explain: Is a Stormwater Provide a general description of planned techniques: Pollution Prevention 6 To Plan (SW3P) /� a established for �..t%L.9 t t of.I F —�K't m project construction? R P _ No //Yes Special Designs — Non - Traditional Methods Are any non - traditional methods (aquatic echosystems, wetland -type detention, natural stream repliction, BMPs for water quality, etc.) proposed for any aspect of subject property project? No Yes If "yes" list general type and location below. Provide full report about the proposed special design(s) including rationale for use and expected benefits. Report must substantiate that stormwater management objectives will not be compromised, and that maintenance cost will not exceed those of traditional design solution(s). Is report provided? Yes No If no explain: V"f/ STORMWATER DESIGN GUIDELINES Page 22 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.14) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Special Designs — Deviation From B -CS Technical Specifications If any design(s) or material(s) of traditional runoff - handling facilities deviate from provisions of B -CS Technical Specifications, check type facility(ies) and explain by specific detail element. Detention elements Drain system elements Channel features Culvert features Swales Ditches Inlets Outfalls Valley gutters Bridges (explain in bridge report) In table below briefly identify specific element, justification for deviation(s). Specific Detail Element Justification for Deviation (attach additional sheets if needed) 1) 2) 3) 4) 5) Have elements been coordinated with the City Engineer or her /his designee? For each item above provide "yes" or "no ", action date, and staff name: 1) 2) 3) 4) 5) Design Parameters Hydrology Is a map(s) showing all Design Drainage Areas provided? / Yes No Briefly summarize the range of applications made of the Rational Formula: g-tg Pt 6 - .21-4 - co�x�t - �2�yes 1< What is the size and location of largest Design Drainage Area to which the Rational Formula has been applied? O acres Location (or identifier): i N.} STORMWATER DESIGN GUIDELINES Page 23 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.15) Design Parameters (continued) Hydrology (continued) In making deterations for time of concentration, was segment analysis used? No V Yes In approximately what percent of Design Drainage Areas? 1 b As to intensity- duration - frequency and rain depth criteria for deterOning runoff flows, were any criteria other than those provided in these Guidelines used? ti No Yes If "yes" identify type of data, source(s), and where applied: For each of the stormwater management features listed below identify the storm return frequencies (year) analyzed (or checked), and that used as the basis for design. Feature Analysis Year(s) Design Year Storm drain system for arterial and collector streets Storm drain system for local streets I I Open channels Swale /buried conduit combination in lieu of channel Swales Roadside ditches and culverts serving them Detention facilities: spillway crest and its outfall ZS t o 0 Detention facilities: outlet and conveyance structure(s) Detention facilities: volume when outlet plugged Culverts serving private drives or streets Culverts serving public roadways Bridges: provide in bridge report. Hydraulics What is the range of design flow velocities as outlined below? Design flow velocities; Gutters Conduit Culverts _ Swales Channels Highest (feet per second) 2_.\ 0 fl -`1% Lowest (feet per second) Streets and Storm Drain Systems Provide the summary information outlined below: Roughness coefficients used: For street gutters: 0-0 k ` For conduit type(s) ArDS _ 0.O t2 Coefficients: STORMWATER DESIGN GUIDELINES Page 24 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 - Drainage Concept and Design Parameters Continued (Page 4.16) Design Parameters (continued) Hydraulics (continued) Street and Storm Drain Systems (continued) For the following, are assumptions other than allowable per Guidelines? Inlet coefficients? ✓No Yes Head and friction losses v No Yes Explain any "yes" answer: In conduit is velocity generally increased in the downstream direction? 4es No Are elevation drops provided at inlets, manholes, and junction boxes? ✓Yes No Explain any "no" answers: Are hydraulic grade lines calculated a'd shown for design storm? ✓ Yes No For 100 -year flow conditions? V Yes No Explain any "no" answers: What tailwater conditions were assumed at outfall point(s) of the storm drain system? Identify each location and explain: muJ err -r Po ol 'FLi \a-r. •J of ss. tI L1T`j Open Channels If a HEC analysis is utilized, does it follow Sec VI.F.5.a? Yes No Outside of straight sections, is flow regime within limits of sub - critical flow? Yes No If "no" list locations and explain: Culverts If plan sheets do not provide the following for each culvert, describe it here. For each design discharge, will operation be outlet (barrel) control or inlet control? Entrance, friction and exit losses: Bridges Provide all in bridge report STORMWATER DESIGN GUIDELINES Page 25 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.17) Design Parameters (continued) . Computer Software What computer software has been used in the analysis and assessment of stormwater management needs and /or the development of facility designs proposed for subject property project? List them below, being sure to identify the software name and version, the date of the version, any applicable patches and the publisher 04 — GPri. Part 5 — Plans and Specifications Requirements for submittal of construction drawings and specifications do not differ due to use of a Technical Design Summary Report. See Section III, Paragraph C3. Part 6 — Conclusions and Attestation Conclusions Add any concluding information here: Attestation Provide attestation to the accuracy and completeness of the foregoing 6 Parts of this Technical Design Summary Drainage Report by signing and sealing below. This report (plan) for the drainage design of the development named in P. B was prepared by me (or under my supervision) in accordance with provisions o -`_ - _ ` N; ■ • •e Station Unified Drainage Design Gu'o elines for the owners of the pro ✓ lirafn : 1 • ermits required by any and all st: - and federal regulatory agen ty he•' bpe -' r ■ • ; age improvem . • • • een is - or fall under applicable ge �,+Imit C1 _ � •. * , 6 /� "-. ��� , _ ► (ffi A ,\ • *. ik RABON A. METCA y Licensed Professional Engin a .' :8583 d State of Texas PE No. e25 ts! " ' `' ',/ �. Off. STORMWATER DESIGN GUIDELINES Page 26 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.17) Design Parameters (continued) Computer Software What computer software has been used in the analysis and assessment of stormwater management needs and /or the development of facility designs proposed for subject property project? List them below, being sure to identify the software name and version, the date of the version, any applicable patches and the publisher 0 tbaz - Cilr. Part 5 — Plans and Specifications Requirements for submittal of construction drawings and specifications do not differ due to use of a Technical Design Summary Report. See Section III, Paragraph C3. Part 6 — Conclusions and Attestation Conclusions Add any concluding information here: Attestation Provide attestation to the accuracy and completeness of the foregoing 6 Parts of this Technical Design Summary Drainage Report by signing and sealing below. This report (plan) for the drainage design of the development named in P- B was prepared by me (or under my supervision) in accordance with provisions o - - T N. , - • e Station Unified Drainage Design Gu'o elines for the owners of the prop., kolietiONIRts : • ermits required by any and all st: - and federal regulatory agen 63 hL'. ape •'e, • : - age improvem - • • _ - • een is- ed or fall under applicable ge perrnits � �•, 1 _� ►��4 (Af !? RABON A. METCA % A i g Licensed Professional Engin - • 8583 • A State of Texas PE No. ��S SS .... ■ Ir`/4. • j i/ ‘ S Nh� �. �o STORMWATER DESIGN GUIDELINES Page 26 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 • SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 - Drainage Concept and Design Parameters Continued (Page 4.16) Design Parameters (continued) Hydraulics (continued) Street and Storm Drain Systems (continued) For the following, are assumptions other than allowable per Guidelines? Inlet coefficients? L. No Yes Head and friction losses t/ No Yes Explain any "yes" answer: In conduit is velocity generally increased in the downstream direction? / 'Yes No Are elevation drops provided at inlets, manholes, and junction boxes? r/ Yes No Explain any "no" answers: Are hydraulic grade lines calculated ad shown for design storm? ✓ Yes No For 100 -year flow conditions? Yes No Explain any "no" answers: What tailwater conditions were assumed at outfall point(s) of the storm drain system? Identify each location and explain: T+,.) -r Poop L-71vA — c as s oi 'T .rTior.1 1 — Are\ 1-1'T`1 Open Channels If a HEC analysis is utilized, does it follow Sec VI.F.5.a? Yes No Outside of straight sections, is flow regime within limits of sub - critical flow? Yes No If "no" list locations and explain: Culverts If plan sheets do not provide the following for each culvert, describe it here. For each design discharge, will operation be outlet (barrel) control or inlet control? Entrance, friction and exit losses: Bridges Provide all in bridge report STORMWATER DESIGN GUIDELINES Page 25 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009