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HomeMy WebLinkAboutDrainage StudyDrainage Study FOR Crossroads Retail Center College Station Brazos County, Texas October 27, 2008 Revision No. 1 -February 2, 2009 Prepared For: Texas KJ Investments, LLC 4405 Regal Oaks Drive College Station, TX 77845 Prepared By: RME Consulting Engineers P.O. Box 9253 College Station, TX 77845 Texas Firm Registration No. F-004695 RME No. 237-0365 TABLE OF CONTENTS: Drainage Study Crossroads Retail Center College Station Brazos County, Texas PAGE 1.0 General Information ...................................................................................................................................... 1 1. I Scope of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 1.2 Site and General Location ....................................................................................................................... I 1.3 Description of Existing Conditions and Drainage Patterns ..................................................................... 1 1.4 FEMA Information .................................................................................................................................. 2 2.0 Watersheds & Drainage Areas ...................................................................................................................... 3 2.1 Detention Facility Watersheds (Existing Conditions) ............................................................................. 3 2.2 Detention Facility Watersheds (Proposed Conditions) ............................................................................ 3 3.0 Hydrologic Modeling ..................................................................................................................................... 4 3. l SCS-TR 20 Formula and Methodology ................................................................................................... 4 3.2 Rational Formula and Methodology ........................................................................................................ 6 3 .3 Stormwater Runoff Quantities ................................................................................................................. 6 4.0 Detention Facility & Routing ........................................................................................................................ 7 4.1 Detention Facility Criteria ....................................................................................................................... 7 4.2 Methodology ............................................................................................................................................ 8 4.3 Detention Facility Configuration ............................................................................................................. 8 4.4 Detention Facility Outlet Structures ........................................................................................................ 9 4.5 Routing Results and Conclusions .......................................................................................................... I 0 5.0 Storm Drainage System ............................................................................................................................... 11 5.1 Culverts .................................................................................................................................................. I I 6.0 Certification .................................................................................................................................................. 12 23 7-0365 Drainage Report-020209 Page -i LIST OF TABLES: PAGE Section 3.0 -Hydrologic Modeling Table # 1: Drainage Basin Runoff Quantities ......................................................................................................... 7 Section 4.0 -Detention Facility Routing Table #2: Pond 2 -Detention Facility Tailwater .................................................................................................. 10 Table #3: Detention Facility Routing ................................................................................................................... 11 Table #4: Discharge Comparisons ........................................................................................................................ 11 Section 5.0 -Storm Drainage System Table #5: Culvert Summary ................................................................................................................................. 12 237-0365 Drainage Report-020209 Page -ii ATTACHMENTS: Section I .O -General Information Final Plat Vicinjty Map FIRM Panel Map Springer Chevron CLOMR Springer Chevron HEC-RAS Section 2.0 -Watersheds & Drainage Areas Carters Creek Watershed Area Existing Conditions Drainage Area Map Proposed Conditions Drainage Area Map Section 3.0 -Hydrologic Modeling HydroCAD -Existing Conditions Drainage Calculations HydroCAD -Proposed Conditions Drainage Calculations Rational Method -Proposed Conditions Section 4.0 -Detention Facility & Routing CI. I: Grading & Drainage Plan HydroCAD -Proposed Conditions Pond Routing Calculations -Pond 1 HydroCAD -Proposed Conditions Pond Routing Calculations -Pond 2 Section 5.0 -Storm Drainage System THYSYS -Hydraulic Computations 237-0365 Drainage Report-020209 Page -iii Drainage Study -Rev. No. 1 Crossroads Retail Center 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 Crossroads Retail Center. This drainage study's scope will analyze the proposed detention facility design methods and proposed configurations, and other storm drainage system improvements that will facilitate this development. All drainage system improvements (i.e. detention facilities, storm sewer, etc ... ) will be designed to accommodate the anticipated ultimate development conditions for this site. 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 commercial development of the Crossroads Retail Center is located on a called 2.064 acre tract platted as Lot 2 of the Harvey Road East subdivision. The Final Plat of this subdivision is provided in the "Attachment -Section 1.0" portion of the report. This subdivision is located in the city limits of College Station and is located on the north side of Harvey Road East (S.H. No. 30) approximately 890 feet east of its intersection with Earl Rudder Freeway (S.H. No. 6). 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. The Crossroads Retail Center in general will consist of the construction of an approximate 18,875 sq.ft. commercial building, a 6,150 sq.ft. building pad site for future development, and accessory uses (i.e. drives, parking, dumpster pad, etc ... ). This development has access to Harvey Road East (S.H. No. 30) along its southeast property line. Developments adjacent to this subject development are Springer's Convenience Center to the southwest, the Lock n' Roll storage facility to the northwest, and Windwood Estates to the southeast. The adjacent tract to the northeast is vacant and undeveloped but is zoned commercial. 1.3 Description of Existing Conditions and Drainage Patterns: The 2.064-acre tract for the Crossroads Retail Center is a poor sloping (less than 1.0%) undeveloped site with natural surface drainage that convey runoff to the unnamed 237-0365 Drainage Report-020209 Page -1 Crossroads Retail Center Drainage Study -Rev. No. l RME Consulting Engineers February 2, 2009 tributary of Carters Creek. This unnamed tributary is well defined, within the boundaries of the subject property, and is improved as a concrete rectangular channel approximately 32 ' deep and roughly 4' deep. This concrete channel is located in a 50' wide drainage easement, to the limit of the subdivision, and is dedicated by plat (Vol. 1122, Page 813). Immediately upstream in this unnamed tributary is a 5-barrell 4'x7' box culvert that conveys runoff under the Springer's Chevron development. Nearly immediately downstream of the project site runoff in the unnamed tributary is conveyed across Harvey Road East by means of a single barrel box culvert. Further downstream, and to its confluence with Carters Creek, the unnamed tributary is not known to be covered by any easements of any kind. Existing land-cover general consists of open grassy areas with some brush, weeds, and scrub trees. Elevations range on the site from approximately 250' Mean Sea Level (MSL) to approximately 259' 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 either directly into the unnamed tributary or into it via the TxDOT bar ditch of SH 30. Runoff is then conveyed in the unnamed tributary across Harvey Road East (SH 30) and by the neighboring Windwood subdivision. The unnamed tributary discharges approximately 900 feet downstream into Carters Creek via a natural drainage way. This natural drainage way is primarily in undeveloped land and is also located in the floodplain zone of Carters Creek. 1.4 FEMA Information: The entire retail development, Crossroads Retail Center, is wholly contained within mapped 100-year floodplain (Zone A-unstudied) as graphically depicted by the Federal Emergency Management Agency (FEMA) -Flood Insurance Rate Map (FIRM) Community/Panel number 480083 0142C, with an effective date of July 2, 1992. A portion of these FIRM Panel Maps are located in the "Attachment -Section 1.0" section of the Drainage Report. In addition to this information "better data" was provided by the City of College Station. Mitchell & Morgan, L.P. performed a hydraulic analysis of the unnamed tributary for the extension of the existing multiple box culverts which are located near the southwest comer of the property for the Springer's Convenience Center. This Springer Chevron CLOMR was approved by FEMA on January 17, 2002 and a copy of this document, along with the Springer Chevron HEC-RAS output data is contained in the "Attachment -Section 1.0" portion of the report. 23 7-0365 Drainage Report-020209 Page -2 Crossroads Retail Center Drainage Study -Rev. No. I 2.0 WATERSHEDS & DRAINAGE AREAS 2.1 Detention Facility Watersheds (Existing Conditions): RME Consulting Engineers February 2, 2009 As previously discussed, Lot 2 of the Harvey Road East subdivision is located in a watershed of an unnamed tributary that drains into the Carters Creek Watershed Area. An exhibit of this watershed has been included in the "Attachment -Section 2.0" appendix of the report. The drainage area of the unnamed tributary, upstream of this development, is estimated to be approximately 400 acres. Since this drainage study will include the hydrologic/hydraulic modeling of two (2) on- site detention facilities, an appropriate drainage area map called the Existing Conditions Drainage Area Map (which is located in the "Attachment -Section 2.0" portion of the Drainage Report), was developed for considerations of runoff patterns and analysis and is described as follows. Drainage Area "Xl" -This drainage area is approximately 0.91 acres and will consist of the southeastern half of the proposed development area at pre-development or existing conditions. At the downstream limit of this drainage area is the bar-ditch of Harvey Road East. Analysis ofthis 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. Drainage Area "X2" -This drainage area is approximately 1.06 acres and will consist of the northwestern half of the proposed development area at pre-development or existing conditions. At the downstream limit of this drainage area is the unnamed tributary of Carters Creek just upstream of its drainage structure crossing with Harvey Road East. 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 three (3) individual drainage basins were considered and analyzed at proposed development conditions and are as follows. The Proposed Conditions Drainage Area Map illustrates these drainage areas and is located in the "Attachment-Section 2.0" section of the Drainage Study. Drainage Area Map "Pl" -This drainage area consists of 1.00 acres and is similar to that of Drainage Area "Xl ". Differences between these two drainage areas are general the slight boundary adjustments do to grading improvements within the commercial development. Proposed runoff conditions from this drainage area will be evaluated at the anticipated development conditions. The hydrologic data generated from this drainage area will be collected and routed through the project's detention facility Pond 1 and discharged into the bar ditch of SH 30. Ultimately, routed flow will be compared to the runoff values generated from Drainage Area "X 1" benchmark data; 237-0365 Drainage Report-020209 Page -3 Crossroads Retail Center Drainage Study -Rev. No. 1 RME Consulting Engineers February 2, 2009 Drainage Area Map "P2" -This drainage area consists of 0.94 acres and is similar to that of Drainage Area "X2". Differences between these two drainage areas are general the slight boundary adjustments do to grading improvements within the commercial development. Proposed runoff conditions from this drainage area will be evaluated at the anticipated development conditions. The hydrologic data generated from this drainage area will be collected and routed through the project's detention facility Pond 2 and discharged into the channelized section of the unnamed tributary of Carters Creek. Ultimately, routed flow will be compared to the runoff values generated from Drainage Area "X2" benchmark data; Drainage Area Map "P3" -This drainage area consists of 0.94 acres and is the contributing drainage area to the proposed driveway culvert located on Harvey Road East (SH No. 30) near the southwest corner of the subject property. Routed flows through the detention facility Pond 1, of Drainage Area "P 1 ", will be added to this drainage area and the cumulative flows will be used to properly size the driveway culvert; 3.0 HYDROLOGIC MODELING 3.1 SCS -TR 20 Formula and Methodology: The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service, developed the runoff curve number method as a means of estimating the amount of rainfall appearing as runoff. The SCS-TR 20 formula calculates the peak discharge and volumes in a reliable fashion for moderate sized (50 to 400 acres) watersheds. This hydrologic method will also be utilized for all detention facility sizing regardless of the size of the contributing drainage area. The SCS unit hydrograph procedure (also known as the TR-20 runoff method) generates a runoff hydrograph by the following basic steps: (For brevity, this is a simplified description.) The SCS-TR20 methodology was employed for hydrologic computations of the Unnamed Tributary's Watershed and Post-Development Watersheds/Drainage Areas. 1. A rainfall distribution is selected which indicates how the storm depth will be distributed over time. This is usually a standardized distribution, such as the SCS Type II storm, and often has a standardized duration of 24 hours; 2. The design storm depth is determined from rainfall maps, based on the return period being modeled. Combined with the rainfall distribution, this specifies the cumulative rainfall depth at all times during the storm; 3. Based on the Time-of-Concentration (Tc), the storm is divided into "bursts" of equal duration. For each burst, the SCS runoff equation and the average Curve Number (CN) are used to determine the portion of that burst that will appear as runoff; The SCS runoff equation determines the precipitation excess runoff that results from a given cumulative precipitation: 237-0365 Drainage Report-020209 Page -4 Crossroads Retail Center Drainage Study -Rev. No. 1 (P-Ia)2 Q= ------------(Q=O if P<Ia) (P-Ia)+S 1000 S= ----------10 CN with Ia= 0.2 S (P-.2S)2 Q= ------------ (P+. 8 S) where, Q =Precipitation excess runoff (inches); RME Consulting Engineers February 2, 2009 P =Cumulative precipitation (inches)-Table C-6 of the USDG; Ia = Initial abstraction (inches); S = Potential maximum retention (inches); CN = Curve Number -The Antecendent Mositure Condition (AMC) 1 and 3 are implemented by adjusting the Curve Numbers. The AMC specifies the moisture level in the ground immediately prior to the storm. Four conditions are defined: 1 - I Dry 2-IINormal 3 -III Wet 4 -Frozen or Saturated It is common policy to use AMC 2 for most design work. Other values should be used only under special circumstances. AMC 3 is sometimes used to study wet conditions, such as a spring rainfall event. AMC 3 usually causes a dramatic increase in runoff, and is not normally used for design purposes. Unless otherwise specified AMC 2 will be utilized for all hydrologic computations that employ the SCS-TR 20 method. 4. A Unit Hydrograph, in conjunction with the Tc, is used to determine how the runoff from a single burst is distributed over time. The result is a complete runoff hydrograph for a single burst; 5. Individual hydrographs are added together for all bursts in the storm, yielding the complete runoff hydro graph for the storm. SCS RUNOFF CURVE NUMBERS "CN": The Soils Conservation Service (SCS) runoff Curve Number, for each watershed, was determined by composite method of percentage of land cover to the total drainage area. These CNs were estimated from the USDG, Table C-7 by comparison of runoff surface types. 237-0365 Drainage Report-020209 Page -5 Crossroads Retail Center Drainage Study -Rev. No. 1 TIME OF CONCENTRATION (Tc): RME Consulting Engineers February 2, 2009 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 remote point in a watershed to the point of analysis. In the case of the drainage study all of the considered drainage areas are relatively small and therefore a Tc of ten minutes will be used in all cases. 3.2 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 hydro logic 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, for the internal storm drain systems, and it is explained further as: Q=CIA where, Q = peak runoff rate (cubic feet per second); C = runoff coefficient -This represents the average runoff characteristics of the land cover within the drainage area and is a dimensionless coefficient. Runoff coefficients are interpolated from either Table C-2 or C-3 of the USDG; I = average rainfall intensity (in/hr); · A = area of land that contributes storm water runoff to the area of study (acres); RUNOFF COEFFICIENT CC): 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. TIME OF CONCENTRATION "Tc": Tc's for the Rational Method will be set at the minimum Tc utilized often (10) minutes. 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 Stormwater Runoff Quantities: Stormwater runoff quantities were calculated, using the SCS-TC 20 formula and Rational Method, with the assistance of the Hydrologic/Hydraulic stormwater modeling program HydroCAD. Runoff values for the larger watersheds are summarized below in Table #1 -"Drainage Basin Runoff Quantities". HydroCAD-Existing Conditions Drainage 23 7-0365 Drainage Report-020209 Page -6 Crossroads Retail Center Drainage Study -Rev. No. 1 RME Consulting Engineers February 2, 2009 Calculations, HydroCAD-Proposed Conditions Drainage Calculations, and Rational Method -Proposed Conditions 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. TABLE#l DRAINAGE BASIN RUNOFF QUANTITIES Drainage Drainage Rainfall Area Area Event (XI) (X2) (yr) (cfs) (cfs) 2 2.60 3.03 5 4.48 5.22 10 5.87 6.84 25 7.05 8.21 50 8.71 10.15 100 10.15 11.82 4.0 DETENTION FACILITY & ROUTING 4.1 Detention Facility Criteria STORAGE: Drainage Drainage Drainage Area Area Area (Pl) (P2) (P3) (cfs) (cfs) (cfs) 4.69 4.41 2.39 6.92 6.51 2.90 8.48 7.98 3.26 9.78 9.19 3.72 11.58 10.89 4.20 13.12 12.33 4.39 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 depth in parking areas shall not exceed six inches; 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. 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 20:1 (5 .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; 237-0365 Drainage Report-020209 Page -7 Crossroads Retail Center Drainage Study -Rev. No. 1 EMERGENCY OVERFLOW: RME Consulting Engineers February 2, 2009 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 3.3 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 are equal to or less than the peak discharge rates of Drainage Area "Xl" and the routed flows through Pond 2 are equal to or less than the peak discharge rates of Drainage Area "X2". 4.3 Detention Facility Configuration: The detention facilities for the Crossroad Retail Center commercial development will consist of two (2) surface detention facilities. With the construction of these detention facilities, called Pond 1 and Pond 2, the appropriate sized outlet structures will be installed to detain/meter increased runoff from Drainage Areas "Pl" and "P2" respectively. The proposed Cl.I : Grading & Drainage Plan for this project more fully depicts these improvements and is contained under the "Attachment -Section 4.0" portion of this report. The detention facilities are briefly summarized below: Pond 1: Runoff from Drainage Area "Pl" is conveyed by means of overland sheet flow. Pond 1 is "dry" pond with a bottom elevation of 257.78' and a maximum berm or 237-0365 Drainage Report-020209 Page -8 Crossroads Retail Center Drainage Study -Rev. No. 1 RME Consulting Engineers February 2, 2009 ponding elevation of258.18'. This detention pond in general is the "front" parking lot of the retail center. Runoff routed through Pond 1 is metered through a four (4) retangular shaped weir structures (drainage flumes) and discharged into the into the adjacent bar- ditch of S.H. No. 30 -Harvey Road East; Pond 2: Runoff from Drainage Area "P2" is conveyed by means of overland sheet flow or by systems of underground storm drainage that discharges runoff into Pond 2. Pond 2 is "dry" pond with a bottom elevation of 255.00' and a maximum berm or ponding elevation of 258.68'. The detention pond in general is the "rear" parking lot of the retail center along with its corresponding underground drainage system. Runoff routed through Pond 2 is metered through a 12" diameter orifice and then discharged into the unnamed tributary/drainage system of Carters Creek by means of a 24" diameter drainage pipe; 4.4 Detention Facility Outlet Structure: The detention facility outlet structures have been designed to accommodate and route collected stormwater runoff, from Drainage Areas "Pl through P3" so that during analyzed/routed rainfall events the post-development discharge rates are less than the "benchmark" discharge values. These "benchmark" discharge values are illustrated in Table # 1 contained in Section 3 .3 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 is four rectangular shaped weirs with the following configuration: • Four (4) rectangular weirs with a 1.75' wide base width and a head equal to O' to 6"; Pond 2: Pond 2 discharge structure is a circular orifice with a 11" diameter placed at the downstream limit of the on-site drainage system. Once runoff is routed/metered through this 11" orifice it is conveyed into the unnamed tributary of Carters Creek by means of a 24" diameter pipe; Tailwater considerations for the outlet of Pond 1 and 2 were made by :frequencies of coincidental occurrence between the upstream watershed and the corresponding subject drainage area. In the case of Pond 1 there is very little upstream influence from the bar- ditch of SH No. 30 and therefore the outlet of this system was set at a free-discharge condition. With Pond 2 discharging into the unnamed tributary the size ratio of contributing drainage areas of the primary system and Pond 2 is approximately 400: 1. Therefore the following storm frequencies were utilized for sizing of the outlet structure of Pond 2. Tailwater elevations, or water surface elevations, produced by the unnamed tributary that influence the Pond 2 outlet structure were obtained from the flood study/HEC-RAS analysis performed on the creek with the Springer's Chevron drainage improvements. The most upstream studied cross-section that crosses the subject property is RS 71 +31. Using the highest upstream cross-section will yield the most conservative backwater impacts on the detention facility outlet structure. Since this HEC-RAS model did not included the evaluation of the 2, 5 & 25-year rainfall event the 10-year and 25- 237-0365 Drainage Report-020209 Page -9 Crossroads Retail Center Drainage Study -Rev. No. l RME Consulting Engineers February 2, 2009 year WSE where substituted in the most conservative fashion. This information is summarized below in Table #2 -"Pond 2 -Detention Facility Tailwater". TABLE#2 POND 2 -DETENTION FACILITY TAIL WATER Pond 2 Unnamed Unnamed RainfaU Tributary Tributary Event Rainfall Event W.S.E. (yr) (yr) (ft) 2 2 253.45 5 2 253.45 10 5 253.45 25 10 253.45 50 10 253.45 100 25 254.72 4.5 Routing Results and Conclusions: Once the project's detention facility and outlet structure was determined, then the hydrograph for Drainage Basins "Pl" and "P2", could be routed through the detention system. The routing of this hydrograph, for each analyzed rainfall event, was accomplished by means of the Hydrologic/Hydraulic stormwater modeling program HydroCAD. The program mathematically solves for continuity between the detention facilities storage capabilities, in respect to height versus storage and height versus discharge rate, with the inflow hydrograph and inputted tailwater conditions. HydroCAD -Proposed Conditions Pond Calculations -Pond 1 and HydroCAD -Proposed Conditions Pond Calculations -Pond 2 and their supporting data are contained the "Attachment-Section 4.0" section of this Drainage Report. As shown below in Table #3 -"Detention Facility Routing", the designed detention facility system can accommodate inflow runoff and adequately detain this stormwater so that the facility's discharge rates are minimally below the respective "benchmark" discharges without overtopping the maximum pool elevation. Table #4 -"Discharge Comparisons" illustrate the combined totals of pre-development runoff rates to the total routed flows. As computed in this table the post-development routed discharge rates are less than the calculated pre-development discharge rates with the exception of the 2-year rainfall event. This increase should be considered negligible. 237-0365 Drainage Report-020209 Page -10 Crossroads Retail Center Drainage Study -Rev. No. 1 TABLE#3 DETENTION FACILITY ROUTING Routed Benchmark Diff. in RME Consulting Engineers February 2, 2009 Rainfall Storage Max. Discharge Discharge Discharge Max. Berrn Event Volume Pool Elev Rate Rate Rate Elev. (yr) (cu.ft.) (ft) (cfs) (cfs) (cfs) (ft) DETENTION POND 1 2 1,797 257.95 3.13 2.60 0.53 258.18 5 2,869 258.02 4.45 4.48 -0.03 258.18 10 3,654 258.06 5.36 5.87 -0.51 258.18 25 4,3 18 258.09 6.12 7.05 -0.93 258.18 50 5,258 258.14 7.16 8.71 -1.55 258.18 100 6,071 258.18 8.05 10.15 -2.10 258.18 DETENTION POND 2 2 293 256.71 3.58 3.03 0.55 258.40 5 1,913 257.99 5.07 5.22 -0.15 258.40 10 2,681 258.11 5.18 6.84 -1.66 258.40 25 3,515 258.19 5.27 8.21 -2.94 258.40 50 4,725 258.29 5.36 10.15 -4.79 258.40 100 5,903 258.37 5.43 11.82 -6.39 258.40 TABLE#4 DISCHARGE COMPARISONS lotal Total Pre-Routed Ditf. in Rainfall Development Discharge Discharge Event Rate Rate Rate (yr) (cfs) (cfs) (cfs) 2 5.63 6.71 1.08 5 9.70 9.52 -0.18 10 12.71 10.54 -2.17 25 15 .26 11.39 -3.87 50 18.86 12.52 -6.34 100 21.97 13.48 -8.49 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 Culverts SYSTEM CRITERIA: 1. Drainage culverts shall be designed to convey the 25-year storm and analyzed during the 100-year rainfall event; 2. For the design storm, the discharge velocity shall not exceed 6.0 fps; 23 7-0365 Drainage Report-020209 Page -11 Crossroads Retail Center Drainage Study -Rev. No. l RME Consulting Engineers February 2, 2009 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; TAILWATER CONSIDERATIONS: Tailwater for the drainage culverts were determined by calculating the water surface elevation of the open-channel immediately downstream of the structure. METHODOLGY & CONCLUSIONS: The hydraulic analysis, for drainage culverts, and corresponding results, were determined by using the THYSYS hydraulic program for stormwater modeling. This TxDOT program's typical use is for modeling gravity drainage culverts. The THYSYS data is summarized, for each culvert, under the THYSYS -Hydraulic Computations (reference "Attachment-Section 5.0" portion of the report). Drainage culverts are summarized below in Table #5 -"Culvert Summary". TABLE#S CULVERT SUMMARY Rainfall Pipe Size Lowest Event Diameter Velocity RunoffQ HWElev. Pvmt Elev. Freeboard (yr) (in) (fus) (cfs) (ft) (ft) (ft) CULVERT P3 2 18 4.57 2.39 254.27 254.85 0.58 5 18 4.74 2.90 254.38 254.85 0.47 10 18 4.96 3.26 254.45 254.85 0.40 25 18 5.10 3.72 254.53 254.85 0.32 50 18 5.24 4.20 254.61 254.85 0.24 100 18 5.29 4.39 254.64 254.85 0.21 6.0 CERTIFICATION "This report for the drainage design of Crossroads Retail Center 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." 237-0365 Drainage Report-020209 Rabon Metcalf, P .E. State of Texas P.E. No. 88583 Texas Firm Registration No. F-004695 Page -12 Section 1.0 GENERAL INFORMATION t VICINITY MAP CROSSROADS RETAIL CENTER: LOT 2 of HARVEY ROAD EAST COLLEGE STATION, TEXAS 500 ZONE X APPROXIMATE SCALE 0 FLOOD INSURANCE RATE MAP BRAZOS COUNTY,- TEXAS AND INCORPORATED AREAS (SEE MAP INDEX FOA PANELS NOT PAINTED) COllEGE STATIOI'. CITY OF UNINCORPORATED AREAS !!Ji!!lli PAN£l SUffll 480082 0142 480083 0142 481195 0142 Notica 11 Um: Tht MAP NUMBER 1hown lltlow shtl'dd llt 1notl whtn pltclng mtp ord11J: tllt COMMUNITY NUMBER 1how11 IDoH 1Jio11hl bt usH on lnsu1111c1 1ppllc1tion1 for Ult wbltCI eomnaunlty. MAP NUMBER 48041C0142 C EFFECTIVE DATE: JULY 2, 1992 Federal Emergency Management Agency Print Date: 1011612008 (printed at scale and type A) Carters Creek FHS -Carters Creek Multi-Profile Run HEC-RAS Plan: Carters Mull River: Carters Creek Reach: Main (ConUnued) ./t.Reach :~-,. ;· RJver sta' "" :-. ·profile '·'--:;·."ci Total.'.::: :: :Min.Ch-El~:-,.,~w.s. Elev.'"' -: cr11 w.s.\-' :·,·i:.G. Elev:. ··E.G.' Slope "· ::._:.ve1. Cbnl i.:=· ,:-..roji'\y111!h '.·=.' '·Froude ~Chi.;, '.i.\{~;}~g:.:,:_:,':•.: <•.H;:: • · · -'· · :·::C·c:,.'.<' '' • ·.'; "·'(c:fS) ~:;:::\ ~(:i;?_.(fl) '';·>\ ':'.(._(:_-jft) .~·~\';;' ,::~\>i. (fl)>~.-':·:· ;•:f~'.;'(ft)";'i"). "''-".'._'(ft/ft)::;-:•::-·-:.:':{ft/s)':':'.':-." ;,·,·•:<:;:;ill)';•;\';·/ :'-i"-':'•:;_:;;:::. ;-(_.-· M8in\·!L£\:T-li1157}'. :;:·-. :110% -:-.::~ <' I 12225.ool 239.721 254.561 251.631 254.671 0.0007161 3.99 Ma1~\;Lj}:;-;,<l815F•'._ ... -.. ,,.12% -: .•.:_-.. ·1 17504.ool 239.721 255.631 251.631 255.nl o.0008371 4.61 '1ati'i:'X .. i\.ih·t 5151<-;·,_,_.:·,. 13 _. "'· "-' 20029.oo 239.72 256.11 251.63 256.26 o.000869 4.82 'Miitn>~;;,,:;'\ 8157}-::;-·.;:._:,_·. 0.2% ,·::. 25040.00 239.72 256.98 251.63 257.16 0.001102 5.69 ~~:{:/~.~:~f:;_:·:: ... ;{1~.\•::-:.~~:. ::·. \:::"-! .. :\~ ::.. Matii.~'J.'•/;:\•"'17510 '-.\:.'" ·.·: '110% t.l&ln/~':1V:l7610 ;:.-,12% · .. Miiill':>:<~-:;•.11510:-:•=.-::.\:11% · .. M.iilri·::",:.:·:;:,<.d7510 ·"" \.,:.'lo.2%. :·· 2~;;;<{;~~"·0i~~'il ,_.~,:-,I .... : .. Maln)c.\:.".-: ·'·17308 ·,. · ·-:--: 110% "·-,., ·: ' · Ma1ii'il'"-·:0>.': 17:308''' "' · 12% · .. MBiii':',Z:-t:;"'il73o8.-::"· ::. ·:11%.-. .-Miiii(:·>"i'li308 ; ..... '..'. :,:.~I0.2% . .... ~~~?,\ ::.'.;·~-·'.-:.! \.'~ ::::·.\:.-.:-. .. f:':•:.-MBtri·>.'i;:~;,;~17245 ':.~·:';":)-l,'j1Q% "-.: . " Mil1r1·~::;->·,\., 1124s_ .. ;,,,,c:.-....-i2% -;~:;>:,-.., Mii1i]";\-•';:: .. yj7245\ -.--: -·:]1% .'," .. ' ,_. ,. "' M.iiiil.?.'.~'('·:~11245;~:-.::.·::.'lo.2%--;z :;~';~i:;;;;-;·:;..";,'.':k';);;'..' . ' MSfn.}'.-£.-i/•17184 :"-.:.:o {".: :·:: .. >::;.··:. .. :7:. F<::.:·: ' .. :;-.·e \ 'V -;-. ."-'.-:;:' .-1 "y, :-. : · · Main'.c:'.'/·:·::.,.11131·:~':.' .-·.--:j1()% ·-.,. !Main ·,·i:, ~· ''17131 · ::~'':12% Maln'-•":.c:,'.\· 7.13L ::':":-.-.:-.-· 1% · ·" ·. MB1r1:·3...:-.:11131 ·-."·'·.:"•·•' lo.2% '·. · · ;_;_;.t'>.:~;:::j .:'::::,.-;;\ ;,•-:-.\.j ._..,,,,_,. ...· Main:,.-.,,.'..~: ::17025 .-:-.:,:: .. 'd10% .\:;::~" ~ Main '-":·.;.~_".-.11025 : ... ".:'-:'.• 12% "" · Main ::::·•.-.'.:._:-.:11025.-\'.::;".;:: •. 11% "·>·,-.. ·'' Maln•::.-.-.,, .. ~;; .. 11025 ·:\'.h"'-lo.2% '-'<'=:·, ;r~<\\:· "::: . .'.f.1'~;C::_:;:·:f.' f\'.•'. ?.:.,.,, .. \1·ain"=.i:''''<;·15559 :.>-'"?:·110%_;.-.. · .. "-. M8tii:-.-..:_; · -.:,;;;ls5a1r>·.," .. ·s12% ;::.:.;;.-~--" Main ,.;;:X·-~'·15569 •:·.-. ........ .-11% • .. .-., : l~~>":_;~/]55a97.:C::]0.2%~;: iMa11i::-'":::::;:-,-13555 , · ·· 110% Mal Malo :-. ··:,-.;:cl3556 11% Main '-'·'i "" ·13556 ·, 'I0.2% · 12225.00 17504.00 20029.00 25040.00 12267.00 17852.00 20483.00 25639.00 12288.00 17681.00 20517.00 25678.00 Mull Open 12288.00 17881.00 20517.00 25678.00 12384.00 18012.00 20670.00 25855.00 12790.00 18569.00 21320.00 26606.00 12785.00 185n.oo 21336.00 26626.00 239.38 239.38 239.38 239.38 239.38 239.38 239.38 239.38 236.96 236.96 236.96 236.96 236.35 236.35 236.35 236.35 236.39 236.39 236.39 236.39 236.14 236.14 236.14 236.14 234.17 234.17 234.17 234.17 254.22 255.25 255.72 256.55 254.15 265.18 255.65 256.47 254.10 255.12 255.59 256.41 253.45 254.72 265.23 256.14 253.39 254.67 255.18 256.09 251.95 253.32 253.83 254.72 249.78 251.22 251.74 252.64 251.19 251.81 252.05 252.46 251.34 251.98 252.23 252.67 249.48 251.71 252.03 252.40 249.88 250.75 251.04 251.55 245.90 248.68 249.01 249.56 254.29 255.33 255.81 256.64 254.22 255.26 255.73 256.56 254.18 255.22 255.69 256.52 253.55 254.81 255.32 256.24 253.47 254.74 255.26 256.17 252.23 253.59 254.11 255.03 250.10 251.54 252.06 252.97 0.000483 0.000542 0.000555 0.000579 0.000605 0.000688 0.000700 0.000752 0.000609 0.000703 0.000721 0.000749 0.000724 0.000667 0.000856 0.000643 0.000742 0.000663 0.000649 0.000633 0.001455 0.001483 0.001537 0.001622 0.001191 0.001190 0.001190 0.001192 3.61 4.03 4.18 4.43 3.64 4.11 4.26 4.61 3.91 4.44 4.81 4.89 4.15 4.27 4.35 4.50 3.76 3.87 3.95 4.12 6.30 6.81 7.10 7.59 5.57 6.03 6.19 6.48 1601.60 1908.04 2169.70 3169.52 2226.14 2377.89 2509.43 2920.29 2210.39 2301.66 2437.97 2816.95 2244.53 2398.86 2476.48 2609.08 2205.80 2267.02 2287.60 2331.40 2224.09 2263.26 2271.55 2288.46 1541.97 1570.51 1581.14 1601.52 1191.10 1339.76 1362.30 1414.57 0.22 0.24 0.25 0.28 0.18 0.19 0.20 0.20 0.20 0.21 0.21 0.22 0.20 0.22 0.22 0.23 0.21 0.21 0.21 0.21 0.22 0.21 0.21 0.21 0.31 0.32 0.33 0.34 0.29 0.30 0.30 0.30 Appendix 87 .. ,, Federal Emergency Management Agency Washington, D.C. 20472 CERTIFIED MAIL RETURN RECEIPT REQUESTED The Honorable Lynn Mcllhaney Mayor, City of College Station P.O. Box 9960 College Station, TX 77842 Dear Mayor Mcllhaney: JAN 172002 IN REPLY REFER TO: Case Number: Community: Community No.: Panel Affected: Effective Date of This Revision: 102-D 01-06-356P City of College Station, Brazos County, Texas 480083 48041C0142 C JAN 17 ZOOZ The Flood Insurance Rate Map (FIRM), for Brazos County, Texas and Incorporated Areas, which includes the City of College Station, has been revised by this Letter of Map Revision (LOMR) to reflect the placement of fill and constru~tion of culverts for the Springer Chevron .. Property. The subject area is located along the Tributary to Carters Creek from a point approximately 80 feet downstream of East Frontage Road to a point approximaiely l,OOO ·feet downstream of East Frontage Road. This revision was initiated by Spencer G. 'fllompson Jr., City of College Station, in a letter dated November 20, 2000. We issued a Conditional Letter of· Map Revision (CLOMR) for this project on May 29, 1996. We received certified hydraulic analysis, as-built plans, an annotated FIRM reflecting post-project conditions, a maintenance agreement for the culverts, fill certification, a revised topographic workmap, and all applicable forms, prepared by Mr. Thompson, in support of this revision. We received all of the data required to perform a technical review of the request as of November 19, 2001. Based on our review of the submitted data, we are issuing this LOMR to reflect the Springer Chevron Property. This LOMR revises the Special Flood Hazard Area (SFHA) for the Tributary to Carters Creek, which is designated Zone A, to show decreases in width. The maximum decrease in the SFHA is approximately 400 feet at a point approximately 125 feet downstream of East Frontage Road. This revision is shown on the enclosed annotated portions of FIRM panel 48041C0142 C, dated July 2, 1992. This revision is effective as of the date of this letter. Any requests to review or alter this determination should be made within 30 days and must be based on scientific or technical data. We based this d~termination on the 1 % annual chance (100-year) discharges computed in the submitted hydrologic model, without considering subsequent changes in watershed characteristics that could have increased discharges. Additionally,·future development of 2 characteristics that could have increased discharges. Additionally, future development of projects upstream may increase discharges, which may increase flood hazards. A comprehensive restudy of your community's flood hazards would consider the cumulative effects of development on discharges subsequent to the publication of the CLOMR, dated May 26, 1996, · and could, therefore, establish greater flood hazards in this area. This LOMR is based on minimum floodplain management criteria established under the National Flood Insurance Program (NFIP). Your community is responsible for approving all floodplain development and for ensuring all necessary permits required by Federal or State law have been received. State, county, and community officials, based on knowledge of local conditions and in the interest of safety, may set higher standards for construction in the SFHA. If the State, county, or community has.adopted more restrictive or comprehensive floodplain management . criteria, these criteria take precedence over the minimum NFIP criteria. This revision has met our criteria for removing an area from the 1 % annual chance floodplain to reflect the placement of fill. The community must ensure that any structures placed within the subject area be constructed such that they are "reasonably safe from flooding." ''Reasonably safe from flooding" means base flood waters will not inundate the land or damage structures to be removed from the SFHA and that any subsurface waters related to the base. flood will not damage exi~ting or proposed ·buildings. The community and engineers should review and use FEMA Technical Bulletin 10-01, Ensuring that Structures Built on Fill In or Near Special Flood Hazard Areas are Reasonably Safe From Flooding, which may be downloaded directly from the Federal Emergency Management Agency (FEMA) website at http://www.fema.gov/mit/tblOprop.pdf. NFIP regulations Subparagraph, 60.3(b )(7) requires communities to ensure that the flood-carrying capacity within the altered or relocated portion of any watercourse is maintained. This provision is incorporated into your community's existing floodplain management ordinances; therefore, responsibility for maintenance of the modified channel and culvert rests with your community. We may request that your community submit a description and schedul~ of channel and culvert maintenance activities. We will not print and distribute this LOMR to primary users, such as local insurance agents or mortgage lenders; instead, the community will serve as a repository for the new data. We encourage you to disseminate the information in this LOMR by preparing for publication in your community's newspaper, a news release that describes the revision and explains how your community will provide the data and help interpret the NFIP maps. In that way, interested persons, such as property owners, insurance agents, and mortgage lenders, can benefit from the information. Use the map panel listed above and revised by this letter for flood insurance policies and renewals issued in your community. We have enclosed an updated version of a document titled List of Current Flood Insurance Study Data, which includes this letter, to help your community maintain all information for floodplain management and flood insurance. If any of the items in that document are not filed in your 3 community's map repository, please contact the FEMA Map Assistance Center at the telephone number listed below for information on how to obtain those items. We have made this determination pursuant to Section 206 of the Flood Disaster Protection Act of 1973 (P.L. 93-234) and in accordance with the National Flood fusurance Act of 1968, as amended (Title XIlI of the Housing and Urban Development Act of 1968, P.L. 90-448), 42 U.S.C. 4001-4128, and 44 CFRPart 65. Pursuant to Section 1361 of the National Flood fusurance Act of 1968, as amended, communities participating in the NFIP are required to adopt and enforce floodplain management ordinances that meet or exceed minimum NFIP criteria. These criteria, including adoption of the FIRM, and the modifications made by this LOMR, are the minimum requirements for continued NFIP participation and do not supersede more stringent State or local requirements to which the regulations apply. If you have any questions regarding this LOMR, please contact the FEMA Map Assistance Center, toll free, at 1-877-FEMA MAP (1-877-336-2627). Sincerely, ~a-~ Lloyd A. Hake, Project Engineer · . Hazards Study Branch Federal fusurance and· Mitigation Administration Enclosures For: Matthew B. Miller, P.E., Chief Hazards Study Branch Federal fusurance and Mitigation Administration cc: Teddy P. Mayo, P.E., Assistant City Engineer Veronica J.B. Morgan, P.E., Mitchell & Morgan, LLP Spencer G. Thompson Jr., City of College Station Community Map Repository, City of College Station LIST OF CURRENT FLOOD INSURANCE STUDY DATA This list is provided to document all information currently effective for your community for insurance and floodplain management. Date: JAN l 7 2002 Community: City of College Station, Brazos County, Texas Community Number: 480083 Page Number: 1 of2 CURRENT EFFECTIVE FLOOD INSURANCE STUDY DATE: February 9, 2000 FLOOD INSURANCE RATE MAP Map Index 48041CINDO Panel Numbers 0141 C, 0142 C, 014:3 C, 0144 C, 0161C,0181 C, 0182 C, and 0200 C 0163 D, 0201 D, and 0205 D LETTERS OF MAP REVISION Panel Numbers 0142C 0143 c 0144C 0163D 0181 c Effective Date February 9, 2000 Effective Date July2, 1992 February 9, 2000 Effective Date September 19, 2000 JAN 1·7 200Z March 21, 2000 December 18, 2000 July 10, 2000 October 14, 1999 May31, 1999 July 10, 2000 July 21, 2000 Page2 of2 LETTERS OF MAP AMENDMENT AND MAP REVISION BASED ON FILL Panel Numbers 0142 c 0143 c 0144C 0161 c BEST AVAILABLE DATA LETTERS None Effective Date February 26, 1999 January 16, 1998 January 9, 1997 August 15, 1995 January 30, 1995 May27, 1999 December 2, 1996 July 29, 1996 · October 20, 1995 May25, 1995 February 23, 1995 -~ ... •. / ZONE X APPROXIMATE SCALE IN FEET 500 0 500 E3E3E3 I NAllOIAL R.llOB lllSUllANCE PIOBRAM FIRM R.ODD INSURANCE RATE MAP BRAZOS COUNTY, TEXAS AND INCORPORATED AREAS (Sl!E MAP INDEX l'Ofl PANELS NOT ..-rall ------ZONE X City of College Station 480083 ZONE X REVISED AREA 1% ANNUAL CHANCE FLOOD DISCHARGE CONTAINED IN CULVERT · Section 2.0 WATERSHEDS & DRAINAGE AREAS Section 3.0 HYDROLOGIC MODELING Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 2-Year Rainfal/=4.50" HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page 1 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-X1: DA-X1 Subcatchment DA-X2: DA-X2 Runoff Area=0.910 ac Runoff Depth>1 .73" Tc=10.0 min CN=73 Runoff=2.60 cfs 0.131 af Runoff Area=1 .060 ac Runoff Depth>1. 73" Tc=10.0 min CN=73 Runoff=3.03 cfs 0.153 af Total Runoff Area= 1.970 ac Runoff Volume= 0.284 af Average Runoff Depth= 1.73" .· Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type 1124-hr 2-Year Rainfal/=4.50" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X1: DA-X1 Runoff = 2.60 cfs@ 12.02 hrs, Volume= 0.131 af, Depth> 1. 73" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 2-Year Rainfall=4.50" Area (ac) CN Description 0.910 73 Pre-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) {ft/ft) (ft/sec) (cfs) 10.0 2 Direct Entry, Existing Conditions Subcatchment DA-X1: DA-X1 Hydrograph Type II 24-hr 2-Year Rainfall=4.50" : Runoff Area=0.910 ac Runoff Volume=0.131 af Runoff Depth>1.7·3". Tc=10.0 min CN=73 I 2.60 cts I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page2 10/24/2008 Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 2-Year Rainfal/=4.50" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X2: DA-X2 Runoff = 3.03 cfs@ 12.02 hrs, Volume= 0.153 af, Depth> 1. 73" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=4.50" Area (ac) CN Description 1.060 73 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions 3- Subcatchment DA-X2: DA-X2 Type II 24-hr 2-Year Rainfall=4.50" Hydrograph Runoff Area=1.060 ac I 3.03 cfs I i 2-Runoff Volume=O~ 153 af ~ Runoff Depth>1. 73" Tc=10.0 min CN=73 o-L.. ...... ...,.... .................... .....,.....~~-..............,...""""""-~_.) .. ~.......,....::;::;;=::;:;:;;:;:;:;:;;:;:;:;:;:;:~ 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 3 10/24/2008 I-Runoff~ Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 5-Year Rainfal/=6.20" HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page4 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-X1: DA-X1 Subcatchment DA-X2: DA-X2 Runoff Area=0.910 ac Runoff Depth>3.00" Tc=10.0 min CN=73 Runoff=4.48 cfs 0.227 af Runoff Area=1.060 ac Runoff Depth>3.00" Tc=10.0 min CN=73 Runoff=S.22 cfs 0.265 af Total Runoff Area= 1.970 ac Runoff Volume= 0.492 af Average Runoff Depth= 3.00" Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 5-Year Rainfal/=6.20" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC . Subcatchment DA-X1: DA-X1 Runoff = 4.48 cfs @ 12.02 hrs, Volume= 0.227 at, Depth> 3.00" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 5-Year Rainfall=6.20" Area (ac) CN Description 0.910 73 Pre-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X1 ~ DA-X1 Hydrograph 5- I 4.48 cts I Type U 24-hr 5-Year 4-. . . ... ... . . . . . . . Rai nfal 1=6.20" Runoff Area=0.91 O ac i 3 -Runoff Volume=o~·221 af .e. ~ Runoff Depth>3.00" ii: 2-Tc=10.0 min GN=73 1- 01-_;_ .................................................................. .;......._, .... ijl;:;;:;:;:;:::_,.,........,.....,:;;::;:;:;:;:;:;:;:;::;::;:;:;:;:;;:;:;:;:;:;:;:;;;:;:;:;:) 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pages 10/24/2008 I -Runoff~ Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 5-Year Rainfaf/=6. 20" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X2: DA-X2 Runoff = 5.22 cfs @ 12.02 hrs, Volume= 0.265 af, Depth> 3.00" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 5-Year Rainfall=6.20" Area (ac) CN Description 1.060 73 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X2: DA-X2 5 -Type II 24-hr 5-Year Rai nfal 1=6.20" Hydrograph 4 -Runoff Area=1.06o· ac Runoff Volume=0.265 af Rur1off Depth>3.o·o" : 2 Tc=10.0 min CN=73· I 5.22 cfs I o.t......,..... ......... ,.:,.,.,.. ................. ...._ ........................... .....-~..;;:;:::........., ......... ..::::;:;:::;:;;:;:;:;::;:;;::;:;::;:;;:;::;:;;;;:;:;:), 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 6 10/24/2008 I-Runoffj Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 10-Year Rainfal/=7.40" HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page? 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SGS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-X1: DA-X1 Subcatchment DA-X2: DA-X2 Runoff Area=0.910 ac Runoff Depth>3.96" Tc=10.0 min CN=73 Runoff=5.87 cfs 0.301 at Runoff Area=1 .060 ac Runoff Depth>3.96" Tc=10.0 min CN=73 Runoff=6.84 cfs 0.350 at Total Runoff Area= 1.970 ac Runoff Volume= 0.651 af Average Runoff Depth= 3.96" Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X1: DA-X1 Runoff = 5.87 cfs @ 12.01 hrs, Volume= 0.301 af, Depth> 3.96" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 10-Year Rainfall=7.40" Area (ac) CN Description 0.910 73 Pre-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 6 5 4 :c .5! 3 u.. 2 Direct Entry, Existing Conditions Subcatchment DA-X1: DA-X1 Hydrograph Type II 24-hr 10-Year Rainfall=7 .40" Runoff Area=o.91 O ac Runoff Volume=0.301 af . Runoff Depth>3.96." : Tc=10.0 min CN=73 5.87 cfs o.l-"'""""'.....,.......,... ......... __......,.........,,.,...,.. .............. ..,.:;;;:;:;:;::;:;:::::;.....,.....,.......,.:::;::;::;;:;:;;:;::;:;;:;:;;:;:;:;::;:;::;:;::;:;;:;:J 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 8 10/24/2008 I-Runoff~ Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X2: DA-X2 Runoff = 6.84 cfs@ 12.01 hrs, Volume= 0.350 af, Depth> 3.96" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 10-Year Rainfall=7.40" Area (ac) CN Description 1.060 73 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X2: DA-X2 Hydrograph 7- Type II 24-hr 10-Year 6 -Rainfall=7 .40" s Runoff Area=1.060 ac-· II Runoff Volume=0.350 af ~ 4-~ Runoff Depth>3.96" ii: 3--T.c=-10.0 min CN=73_ 2- 1- I 6.84 cts I o.L.------,----._.....,._......,........,.,,_._,...;;:;:;::;:;::::......,........,.,_..:;::::;:::;:;:;:;:;:;;;:;::;:;:;;:;:;;::;:;:~ 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page9 10/24/2008 I-Runoff. Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 25-Year Rainfal/=8.40" HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page 10 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-X1: DA-X1 Subcatchment DA-X2: DA-X2 Runoff Area=0.910 ac Runoff Depth>4. 79" Tc=10.0 min CN=73 Runoff=7.05 cfs 0.364 af Runoff Area=1 .060 ac Runoff Depth>4.79" Tc=10.0 min CN=73 Runoff=B.21 cfs 0.424 af Total Runoff Area= 1.970 ac Runoff Volume= 0.787 af Average Runoff Depth= 4.79" Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 25-Year Rainfal/=8.40" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X1: DA-X1 Runoff = 7.05 cfs@ 12.01 hrs, Volume= 0.364 af, Depth> 4. 79" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=8.40" Area (ac) CN Description 0.91 O 73 Pre-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X1: DA-X1 Hydrograph 7 Type II 24-hr 25-Year 6 Rainfall=8~40" ,. 5 3 Runoff Area=0_.910 ac Runoff Volume=0.364 af Runoff Depth>4. 79" ; Tc:;::.1.0.0. m.in CN:::;73. 2 .. ·············· ..•................... 7.05 cfs o.:l... .................................. _...........,._..........,....-.,.....~~:;;:;;:....,........,.......::;:;:;:;:;:;;;:;;::;::;:;,:;:;:;::;:;::;::;:;::;:;:;;::;::;;;;;;J 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 11 10/24/2008 I-Runoff~ Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 25-Year Rainfall=B.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X2: DA-X2 Runoff = 8.21 cfs @ 12.01 hrs, Volume= 0.424 af, Depth> 4.79" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 25-Year Rainfall=8.40" Area (ac) CN Description 1.060 73 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 9 8 7 6 3 2 Direct Entry, Existing Conditions Subcatchment DA-X2: DA-X2 Hydrograph Type 1124-hr25-Year- Rainfall=S.40" Runoff Area=1 .060 ac :. Runoff Volume=0.424 af Runoff Depth>4. 79" T.c=10.0 min CN=73 8.21 cfs o+,.......,....."""'T".........;..,...,...,........,..........;.._...,....-..,...,....:;:;:;:;::;;:::;::::.........,......,.......:;:;:;:;;::;;;:;:;::;:;:;;:;::;:;:;;:;::;::;:;:;::~ 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 12 10/24/2008 I-Runoff~ Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 50-Year Rainfa/1=9. 80" HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page 13 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-X1: DA-X1 Subcatchment DA-X2: DA-X2 Runoff Area=0.910 ac Runoff Depth>S.99" Tc=10.0 min CN=73 Runoff=8.71 cfs 0.454 af Runoff Area=1 .060 ac Runoff Depth>5.99" Tc=10.0 min CN=73 Runoff=10.15 cfs 0.529 af Total Runoff Area= 1.970 ac Runoff Volume= 0.983 af Average Runoff Depth= 5.99" Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X1: DA-X1 Runoff = 8.71 cfs@ 12.01 hrs, Volume= 0.454 af, Depth> 5.99" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 50-Year Rainfall=9.80" Area (ac) CN Description 0.910 73 Pre-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions ~ Subcatchment DA-X1: DA-X1 Hydrograph 9- a-Type ll.24~hr 50-Year 7_ Rainfall=~.80" 6- 5 4 3 2 Runoff Area=0.910 ac . . Runoff Volume=0~454 af Runoff Depth>5.99" · Tc=10.0 min CN=73 I 8.71 cts 1. o.:l.... ......................................................... ....-.-...... ii;:;::;::;:;::;:;:;::;::;::;::::,_...,._.,.,....,.::=:;;:;;:;::;;:;:;::;:;:;::;:;::;:;;;;:;;:;::~ 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 14 10/24/2008 I-Runoff ~ Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X2: DA-X2 Runoff = 10.15 cfs@ 12.01 hrs, Volume= 0.529 af, Depth> 5.99" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 50-Year Rainfall=9.80" Area (ac) CN Description 1.060 73 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions 11 10 9 8 1 Subcatchment DA-X2: DA-X2 Hydrograph . . Type 11. 24-h~. 50-Y~ar Rainfall=9.80" . . . Runoff Area=1.060 ac Runoff Volume=0.529 af Runoff Depth>5.99" Tc=10.0 min CN=73 10.15cfs ol-_,..,__..._..... ................................... ....---..-.""'""";;::;:;:;:;;::::;:;:......,...,......,..,..,:::;::;:;:;;;;::;:;::;:;:;::;::;:;:;;;::;:;:;::;::;::;:;::;,;:;:;:;:J, 0 2 3 4 5 6 1 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 15 10/24/2008 Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Existing Conditions Drainage Calculations Type 1124-hr 100-Year Rainfal/=11.00" HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page 16 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Star-Ind+ Trans method -Pond routing by Star-Ind method Subcatchment DA-X1: DA-X1 Subcatchment DA-X2: DA-X2 Runoff Area=0.910 ac Runoff Depth>7.03" Tc=10.0 min CN=73 Runoff=10.15 cfs 0.533 af Runoff Area=1 .060 ac Runoff Depth>7.03" Tc=10.0 min CN=73 Runoff=11 .82 cfs 0.621 af Total Runoff Area= 1.970 ac Runoff Volume= 1.155 af Average Runoff Depth= 7.03" Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type II 24-hr 100-Year Rainfal/=11.00" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X1: DA-X1 Runoff = 10.15 cfs@ 12.01 hrs, Volume= 0.533 at, Depth> 7 .03" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 100-Year Rainfall=11 .00" Area (ac) CN Description 0.91 O 73 Pre-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X1: DA-X1 Hydrograph 11 10.15cfs Page 17 10/24/2008 I -Runoff~ Crossroads-TR20 A-102708 HydroCAD-Existing Conditions Drainage Calculations Type 1124-hr 100-Year Rainfal/=11.00" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-X2: DA-X2 Runoff = 11 .82 cfs@ 12.01 hrs, Volume= 0.621 at, Depth> 7.03" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=11.00" Area (ac) CN Description 1.060 73 Existing Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X2: DA-X2 Hydrograph 13 11.82 cfs 12 -- 11 Type II 24-hr 100-Year 10 Rainfall=11 .00" 9 -Runoff Area=1 ~060 a·c .. 8 Runoff Volume=0.621 af ~ ~ 7 ~ ~unoff Depth>7.03" .2 6 LL Tc=1.0.0 min 5 4 CN=73 3 2 o-l-.....,..........;..........,~.,......,....,..........,..~~~;;;:;=;:;::;:;:;:;;:;:;:::;;:........,.......~.::;:::::;:;:;:;:;:;;;:;:;::;:;:;:;::;:;:;:;:;:;::;:;:;:;;:;:I 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 . 17 18 19 20 Time (hours) Page 18 10/24/2008 Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 2-Year Rainfal/=4.50" HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page 1 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-P1: DA-P1 Subcatchment DA-P2: DA-P2 Runoff Area=1 .000 ac Runoff Depth>2.99" Tc=10.0 min CN=88 Runoff=4.69 cfs 0.249 af Runoff Area=0.940 ac Runoff Depth>2.99" Tc=10.0 min CN=88 Runoff=4.41 cfs 0.234 af Total Runoff Area= 1.940 ac Runoff Volume= 0.483 af Average Runoff Depth= 2.99" Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 2-Year Rainfa//=4.50" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P1: DA-P1 Runoff = 4.69 cfs@ 12.01 hrs, Volume= 0.249 af, Depth> 2.99" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=4.50" Area (ac) CN Description 1.000 88 Post-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 5 4 2 Direct Entry, Proposed Conditions Subcatchment DA-P1: DA-P1 Type II 24-hr 2-Year Rainfall=4.50" · Hydrograph Runoff Area=1.000 ac Runoff Volume=0.249 af Runoff Depth>2.99". Tc=10.0 min CN=88 4.69 cfs o.i.......,... ................ ..,......,..,.,.........,. ........ .,,_._.,.....,~:;:;:;:;::;:;:;:;;:;::::,..... __ _....::;:::;:;:::;:;:;;:;:;::;:;:;:;::;:;:;;:;:;:;:;:;;:;:;:;:J 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 nme (hours) Page2 10/24/2008 I -Runoff~ Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 2-Year Rainfal/=4.50" Prepared by {enter your company name here} HydroCAD® 7 .1 O sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P2: DA-P2 Runoff = 4.41 cfs@ 12.01 hrs, Volume= 0.234 af, Depth> 2.99" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=4.50" Area (ac) CN Description 0.940 88 Ultimate-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 4 3 2 Direct Entry, Proposed Conditions Subcatchment DA-P2: DA-P2 Hydrograph Type II 24-hl" 2-Year : Rai nfal 1=4.50" Runoff Area=0.940 ac Runoff Vohime=0.234 af Runoff Depth>2.99" Tc=10.0 min CN=88 4.41 cfs o.i..........__,.,_.,...,........,....,........,......,...-.....-~;;;:;;;;;:::;:~,...........,.....:;::::;:;:;::;:;:;:;;;::y:;::;:;:::;:;:;:;:;:;:;::~ 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 3 10/24/2008 I-Runoff~ Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Proposed Conditions Drainage Calculations Type 1124-hr 5-Year Rainfa/1=6.20" HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page4 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-P1: DA-P1 Subcatchment DA-P2: DA-P2 Runoff Area=1 .000 ac Runoff Depth>4.52" Tc=10.0 min CN=88 Runoff=6.92 cfs 0.377 af Runoff Area=0.940 ac Runoff Depth>4.52" Tc=10.0 min CN=88 Runoff=6.51 cfs 0.354 af Total Runoff Area= 1.940 ac Runoff Volume= 0.731 af Average Runoff Depth= 4.52" Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 5-Year Rainfa//=6.20" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P1: DA-P1 Runoff = 6.92 cfs@ 12.01 hrs, Volume= 0.377 af, Depth> 4.52" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 5-Year Rainfall=6.20" Area (ac) CN Description 1.000 88 Post-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions 7 -- 6 5 Subcatchment DA-P1: DA-P1 Type U 24-hr 5-Year - Rainfall=6~·20" Hydrograph Runoff Area;::1.000 ac I 6.92 cfs I .,_ .• i" Runoff Volume=0.37.7 af .e ~ 4 --Runoff Depth>4.52" - ii: 3 Tc=10.0 .min. CN=88. 2 1 .....•... 0 0 2 3 4 5 6 7 8" 9 10 11 12 1°3 . 14 15 16 17 18 19 20 Tima (hours) Page5 10/24/2008 I-Runoff~ Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 5-Year Rainfal/=6.20" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P2: DA-P2 Runoff = 6.51 cfs @ 12.01 hrs, Volume= 0.354 af, Depth> 4.52" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 5-Year Rainfall=6.20" Area {ac) CN Description 0.940 88 Ultimate-Development Conditions Tc Length Slope Velocity Capacity Description {min) {feet) {ft/ft) {ft/sec) {cfs) 10.0 7 6 5 3 2 Direct Entry, Proposed Conditions Subcatchment DA-P2: DA-P2 Hydrograph Type II 24-hr 5-Year Rainfall=6.20" Runoff Area=0.940 ac ·· Runoff Volume=0 .. 354 af Runoff Depth>4.52" Tc=10.0 min· CN=88 6.51 cfs o.i....,....,....,.,...;.........,.........,.,.........;..._.,. ..... ..,.:;:;;;:;::;:;;:;:;:;:::;::.;:;::;:::::.....,.......,........:::;:::;;:;;:;:;::;:;;:;::;:;;::;:::;:;:;:;:;:;;;:;:;;;:;::;:) 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 6 10/24/2008 I -Runoff~ Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type 1124-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P1: DA-P1 Runoff = 8.48 cfs @ 12.01 hrs, Volume= 0.469 af, Depth> 5.62" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=7.40" Area (ac) CN Description 1.000 88 Post-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 9 8 7 6 ~ ~ 5 ~ 0 ii: 4 3 2 1- 0 0 Direct Entry, Proposed Conditions Subcatchment DA-P1: DA-P1 Hydrograph Type 1124-hr 10-Year Rainfall=7.40" : ~unoff Area=1.0()0 ac Runoff Volume=0.469 af Runoff Depth>S.62" Tc=10.0 min CN=88 · 1 8.48 cts I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 8 10/24/2008 I -Runoff~ Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P2: DA-P2 Runoff = 7.98 cfs@ 12.01 hrs, Volume= 0.441 af, Depth> 5.62" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 10-Year Rainfall=7.40" Area (ac) CN Description 0.940 88 Ultimate-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA-P2: DA-P2 Hydrograph I 7.98 cfs I 8- Type II 24-hr 10-Year 7-Rai nfa 11=7 .40" 5-· Runoff-Area=0.940 ac i' 5-Runoff Vol.ume=0.441 af .!:!. ~ 4_ Runo~ Dept_h>5.62" ii: Tc=10.0 min 3-CN=88 2- 1- o.:l.......,.. ........ ....,.....,.........,....-~, . ....-.~.-~-""""·-~--::;:::;:;::;::;::;:;::;::;::;:;:;:;;:::::;.,._...,...~:::;:;:;;;::;:::;:;:;:;::;;:;:::;;::;:;:;:;:::;:;::;::;:;:;;,:;...J 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page9 10/24/2008. I-Runoff~ I •JUI v'""ru.,1-1 I VtJV~VU '-'VI IUIUVI ·~ I.JI CUI ICl~C VCll\.IUICIUVI ·~ Crossroads-TR20 A-102708 Type II 24-hr 25-Year Rainfal/=8.40" Prepared by {enter your company name here} · HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page 10 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-P1: DA-P1 Subcatchment DA-P2: DA-P2 Runoff Area=1 .000 ac Runoff Depth>6.55" Tc=10.0 min CN=88 Runoff=9.78 cfs 0.546 af Runoff Area=0.940 ac Runoff Depth>6.55" Tc=10.0 min CN=88 Runoff=9.19 cfs 0.513 af Total Runoff Area= 1.940 ac Runoff Volume= 1.059 af Average Runoff Depth= 6.55" Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 25-Year Rainfal/=8.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P1: DA-P1 Runoff = 9.78 cfs@ 12.01 hrs, Volume= 0.546 at, Depth> 6.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=8.40" Area (ac) CN Description 1.000 88 Post-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions ~ Subcatchment DA-P1: DA-P1 10 9 Type II 24-h~ 25-Year 8 . Rainfall=S.40" 7 Hydrograph 9.78 cfs .2 5 Runoff Area=1.000 ac Runoff Volume=0.546 af Runoff Depth>6.55" Tc=10.0 min u.. 4 CN=88 2 ol.... ................ .__.;._,_._.,..,__. __ ~.~.~--~-.:;:;::;:;:;::;;:;;;;::;:::;:;;:;._.,......,., ......... .::;:;:::::;:;:;:;:::;:;:;:;:::;::;::;::;::;:;:;::;:;:;;:;;:;:;;;;:;:J 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 11 10/24/2008 I-Runoff. Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 25-Year Rainfall=B.40" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P2: DA-P2 Runoff = 9.19 cfs@ 12.01 hrs, Volume= 0.513 af, Depth> 6.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 25-Year Rainfall=8.40" Area (ac) CN Description 0.940 88 Ultimate-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 10 9 8 7 ~ 6 ~ ~ 5 0 ii: 4 3 2 1- 0 0 Direct Entry, Proposed Conditions Subcatchment DA-P2: DA-P2 Hydrograph ' -·-. -Type II 24-hr 25-Year Rainfall=S.40" Runoff Area=0 ~940 ac Runoff Volume=0.513 af -Runoff Depth>6.55" Tc=10.0 min cN=ss 9.19 cfs 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 12 10/24/2008 I-Runoff I Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 50-Year Rainfal/=9.80" HydroCAD® 7 .1 O sin 003394 © 2005 HydroCAD Software Solutions LLC Page 13 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SGS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-P1: DA-P1 Subcatchment DA-P2: DA-P2 Runoff Area=1 .000 ac Runoff Depth>7.86" Tc=10.0 min CN=88 Runoff=11 .58 cfs 0.655 af Runoff Area=0.940 ac Runoff Depth>7.86" Tc=10.0 min CN=88 Runoff=10.89 cfs 0.615 af Total Runoff Area= 1.940 ac Runoff Volume= 1.270 af Average Runoff Depth= 7.86" Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type 1124-hr 50-Year Rainfal/=9.80" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P1: DA-P1 Runoff = 11 .58 cfs@ 12.01 hrs, Volume= 0.655 af, Depth> 7.86" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 50-Year Rainfall=9.80" Area (ac) CN Description 1.000 88 Post-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (tuft) (fUsec) (cfs) 10.0 12 11 10 9 8 J!! 7-. ~ :i: 6 0 ii: 5 4 3 2 1-. 0 0 Direct Entry, Proposed Conditions Subcatchment DA-P1: DA-P1 Type II 24-hr.·SO-Year Rainfall=9.80" Hydrograph Runoff Area::1.ooo a·c . . . ~ Runoff Volume=0.655 af . --. Runoff Depth> 7 .86" Tc=10.0 min. CN=88 11.58cfs 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 14 10/24/2008 I -Runoff~ Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P2: DA-P2 Runoff = 10.89 cfs@ 12.01 hrs, Volume= 0.615 af, Depth> 7.86" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 1124-hr 50-Year Rainfall=9.80" Area (ac) CN Description 0.940 88 Ultimate-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (tuft) (fUsec) (cfs) 10.0 12 4 3 2 Direct Entry, Proposed Conditions Subcatchment DA-P2: DA-P2 Type.II. 24-hr 50-Year Rainfall=9.80" Hydrograph Runoff Area=0.940-ac Runoff Volume=0.61~5 af ·Runoff Depth>7.86" Tc=10.0 min: CN=88 •I 'I • 'I '••• •I 'I ' 10.89 cfs 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 15 10/24/2008 1-Runoffj Crossroads-TR20 A-102708 Prepared by {enter your company name here} HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 100-Year Rainfa/1=11 .00" HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page 16 10/24/2008 Time span=0.00-20.00 hrs, dt=0.05 hrs, 401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-lnd+ Trans method -Pond routing by Stor-lnd method Subcatchment DA-P1: DA-P1 Subcatchment DA-P2: DA-P2 Runoff Area=1.000 ac Runoff Depth>8.98" Tc=10.0 min CN=88 Runoff=13.12 cfs 0.748 af Runoff Area=0.940 ac Runoff Depth>8.98" Tc=10.0 min CN=88 Runoff=12.33 cfs 0.703 af Total Runoff Area= 1.940 ac Runoff Volume= 1.451 af Average Runoff Depth = 8.98" Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type II 24-hr 100-Year Rainfal/=11.00" Prepared by {enter your company name here} HydroCAD® 7 .1 O sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P1: DA-P1 Runoff = 13.12 cfs @ 12.01 hrs, Volume= 0.748 at, Depth> 8.98" Runoff by SGS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=11.00" Area (ac) CN Description 1.000 88 Post-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions 14 13 12 11 10 Subcatchment DA-P1 : DA-P1 Hydrograph Type 1124-hr 100-Year Rainfall=11.oo~· Runoff Area=1.000 ac 13.12 cfs 9 . .. i a Runoff Volume=O. 748 af ~ ~ 1 Runoff Depth>8.98" ii: s · Tc=10.0 min. s CN::i:88 4 3 2 o.l...~-----------..~---~-~--~.;:;:::;:::;::~. :;:::;::;:;::;:::;:::;:~::,. ...................... ~;::::;:;:;:;:;:;::;::;:;:;~.;::;::;:::;::;:;::;:;:;::;:;:;;;.J 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 17 10/24/2008 Crossroads-TR20 A-102708 HydroCAD-Proposed Conditions Drainage Calculations Type 1124-hr 100-Year Rainfa//=11.00" Prepared by {enter your company name here} HydroCAD® 7.1 O sin 003394 © 2005 HydroCAD Software Solutions LLC Subcatchment DA-P2: DA-P2 Runoff = 12.33 cfs@ 12.01 hrs, Volume= 0.703 af, Depth> 8.98" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Type 11 24-hr 100-Year Rainfall=11.00" Area (ac) CN Description 0.940 88 Ultimate-Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) {ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA-P2: DA-P2 Hydrograph Type 1124-h~100:-year Rainfall=11.00" Runoff Area=0.940 ac Runoff Volume=0.703 af· Runoff Depth>8~98" Tc=10.0 min- CN=88 12.33 cfs 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Page 18 10/24/2008 I-Runoff I RATIONAL METHOD -PROPOSED CONDITIONS GENERAL INFORMATION Description: DRAINAGE AREA "P3" Drainage Area = Coefficient of Runoff (Cwro) = 0.85 acres 0.44 TIME OF CONCENTRATION <Tel GIVEN Maximum Travel Distance (D1) = 0 ft Velocity of Runoff (VcREEK) = Maximum Travel Distance (D2) = Velocity of Runoff (VcHANNEd = Maximum Travel Distance (D3) = Velocity of Runoff (V3) = 3.50 ft/sec 690 ft ft 3.00 fsec 0 ft ft 0.75 fsec -NOTE: Minimum Tc allowed = 10 min. 2 YEAR FREQUENCY, RA TE OF DISCHARGE (Q) Coefficient ( e) = Coefficient {b) = Coefficient ( d} = 0.806 65 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.785 Coefficient (b) = 76 Coefficient (d) = 8.5 10 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = 0.763 Coefficient {b) = 80 Coefficient {d) = 8.5 25 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient ( e) = Coefficient (b) = Coefficient ( d) = 0.754 89 8.5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.745 Coefficient (b) = Coefficient ( d) = 98 8.5 100 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = 0.73 Coefficient (b) = 96 Coefficient ( d} = 8 RESULT Tc1= Tc2= Tc3 = Tc= Rainfall Intensity (12) = Q2= Rainfall Intensity (15) = Qs= Rainfall Intensity (110) = Q1o= Rainfall Intensity (125) = Q2s= Rainfall Intensity (150) = Q50= Rainfall Intensity (1100) = Q1oo= 0.0 min. 3.8 min. 0.0 min. 3.8 min. 6.327 in/hr 2.39 cfs in/ 7.693 hr 2.90 cfs 8.635 in/hr 3.26 cfs 9.861 in/hr 3.72 cfs in/ 11.148 hr 4.20 cfs in/ 11 .639 hr 4.39 cfs Section 4.0 DETENTION FACILITY & ROUTING HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 2-Year Rainfal/=4. 50" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P1: Pond 1 for 2-Year event 0.249 at Page 1 21212009 Outflow = Primary = 1.000 ac, Inflow Depth> 2.99" 4.69 cfs@ 12.01 hrs, Volume= 3.13 cfs @ 12.10 hrs, Volume= 3.13 cfs @ 12.10 hrs, Volume= 0.249 at, Atten= 33%, Lag= 5.6 min 0.249 at Routing by Stor-lnd method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 257.95'@ 12.10 hrs Surf.Area= 13,555 sf Storage= 1,797 cf Plug-Flow detention time=6.1 min calculated for 0.249 at (100% of inflow) Center-of-Mass det. time= 5. 7 min ( 771 .5 -765.8 ) Volume Invert Avail.Storage Storage Description #1 257.68' 6, 125 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation (feet) Surf.Area (sq-ft) Inc.Store (cubic-feet) Cum.Store (cubic-feet) 257.68 258.00 258.18 Device Routing #1 Primary 0 16,360 22,611 0 2,618 3,507 Invert Outlet Devices 257.68' 0 X 4.00, C= 2.62 Head (feet) 0.00 0.50 Width (feet) 1.75 1.75 0 2,618 6,125 Primary OutFlow Max=3.12 cfs@ 12.10 hrs HW=257.94' (Free Discharge) t......1 =O (Weir Controls 3.12 cfs @ 1. 7 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 2-Year Rainfal/=4.50" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page2 2/2/2009 5 4 2 0 0 0 258.18 258.16 258.14 258.12 258.1 258.08 258.06 258.04 258.02- -258 t7.98 7.96 lt57.94 ,j57.92 ~257.9 ~57.88 57.86 257.84 257.82 257.8 257.78 257.76 257.74 257.72 257.7 257.68 0 Pond P1: Pond 1 Hydrograph 4.69 cfs Inflow Area=1.000 ac Peak Elev=257 .95' Storage=1, 797 cf 3.13 cfs 2 3 4 5 6 7 8 9 10 11 12 13 Time (hours) Pond P1: Pond 1 Stage-Area-Storage Surface/Horizontal/Wetted Area (sq-ft) 2,000 4,000 6,000 8,000 10,000 12,000 14,000 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 Storage (cubic-feet) -Inflow -Primary 14 15 16 17 18 19 20 16,000 18,000 20,000 22,000 -Surface -Storage 4,500 5,000 5,500 6,000 HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 5-Year Rainfal/=6.20" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P1 : Pond 1 for 5-Year event 0.377 at Page 3 21212009 Outflow = Primary = 1.000 ac, Inflow Depth > 4.52" 6.92 cfs@ 12.01 hrs, Volume= 4.45 cfs @ 12.11 hrs, Volume= 4.45 cfs @ 12.11 hrs, Volume= 0.376 at, Atten= 36%, Lag= 5.9 min 0.376 at Routing by Stor-lnd method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.02'@ 12.11 hrs Surf.Area= 16,885 sf Storage= 2,869 cf Plug-Flow detention time=6.8 min calculated for 0.376 at (100% of inflow) Center-of-Mass det. time= 6.4 min ( 762.4 -756.0 ) Volume Invert Avail.Storage Storage Description #1 257.68' 6, 125 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation (feet) Surf.Area (sq-ft) Inc.Store (cubic-feet) Cum.Store (cu bi c-f eet) 257.68 258.00 258.18 Device Routing #1 Primary 0 16,360 22,611 0 2,618 3,507 Invert Outlet Devices 257.68' OX 4.00, C= 2.62 Head (feet) 0.00 0.50 Width (feet) 1. 75 1. 75 0 2,618 6,125 Primary OutFlow Max=4.42 cfs@ 12.11 hrs HW=258.01' (Free Discharge) "t._1=0 (Weir Controls 4.42 cfs@ 1.9 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 5-Year Rainfal/=6. 20" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page4 21212009 Pond P1: Pond 1 Hydrograph 7 6.92 cfs -Inflow -Primary Inflow Area=1.000 ac 6 Peak Elev=258.02' Storage=2,869 cf 5 4.45 cfs 3 2 0 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond P1 : Pond 1 Stage-Area-Storage Surface/Horizontal/Wetted Area (sq-ft) 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 20,000 22,000 -Surface 258.18 -Storage 258.16 258.14 258.12 258.1 258.08 258.06 258.04 258.02- -258- t7.98 7 96 lt57.94 ,i57.92 ~57.9 - ~57.88- 57.86 257.84-; 257.82~ 257.8 257.78 257.76 257.74 257.72 257.7 257.68 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 Storage (cubic-feet) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 10-Year Rainfa/1=7.40" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Outflow = Primary = Pond P1: Pond 1 1.000 ac, Inflow Depth > 5.62" for 8.48 cfs @ 12.01 hrs, Volume= 5.36 cfs @ 12.11 hrs, Volume= 5.36 cfs @ 12.11 hrs, Volume= 10-Year event 0.469 af 0.468 af, Atten= 37%, 0.468 af Routing by Stor-lnd method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.06'@ 12.11 hrs Surf.Area= 18,430 sf Storage= 3,654 cf Plug-Flow detention time=7.2 min calculated for 0.468 af (100% of inflow) Center-of-Mass det. time=6.8 min ( 757.6 -750.8) Volume Invert Avail.Storage Storage Description Page 5 2/2/2009 Lag= 6.1 min #1 257.68' 6, 125 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation (feet) 257.68 258.00 258.18 Device Routing #1 Primary Surf.Area (sq-ft) 0 16,360 22 ,611 Inc.Store (cubic-feet) 0 2,618 3,507 Cum.Store (cubic-feet) 0 2,618 6,125 Invert Outlet Devices 257.68' 0 X 4.00, C= 2.62 Head (feet) 0.00 0.50 Width (feet) 1.75 1.75 Primary OutFlow Max=5.33 cfs@ 12.11 hrs HW=258.06' (Free Discharge) -t_1=0 (Weir Controls 5.33 cfs@ 2.0 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page6 21212009 Pond P1: Pond 1 Hydrograph 9 8.48 cfs 8 Inflow Area=1.000 ac 1 Peak Elev=258.06' Storage=l,654 cf 6 5.36 cfs 3 2 0 0 2 3 4 5 6 7 8 9 10 11 12 13 Time (hours) Pond P1: Pond 1 Stage-Area-Storage Surface/Horizontal/Wetted Area (sq-ft) 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 258.18 258.16 258.14 258.12 258.1- 258.08 258.06 258.04 258.02 -258 t7.98 7.96 ~57.94 j57.92 ~257.9 ~57.88 57.86 257.84 257.82 257.8 257.78 257.76 257.74 257.72 257.7 257.68 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 Storage (cubic-feet) -Inflow -Primary 14 15 16 17 18 19 20 16,000 18,000 20,000 22,000 -Surface -Storage 4,500 5,000 5,500 6,000 HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 25-Year Rainfall=B.40" Prepared by {enter your company name here} HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P1: Pond 1 for 25-Year event 0.546 af Page 7 21212009 Outflow = Primary = 1.000 ac, Inflow Depth > 6.55" 9. 78 cfs @ 12.01 hrs, Volume= 6.12 cfs @ 12.11 hrs, Volume= 6.12 cfs @ 12.11 hrs, Volume= 0.545 af, Atten= 37%, Lag= 6.1 min 0.545 af Routing by Star-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.09'@ 12.11 hrs Surf.Area= 19,640 sf Storage= 4,318 cf Plug-Flow detention time=7.5 min calculated for 0.545 af (100% of inflow) Center-of-Mass det. time=7.1 min ( 754.2-747.2) Volume Invert Avail.Storage Storage Description #1 257.68' 6, 125 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation (feet) Surf.Area (sq-ft) Inc.Store (cubic-feet) Cum.Store (cubic-feet) 257.68 258.00 258.18 Device Routing #1 Primary 0 16,360 22,611 0 2,618 3,507 Invert Outlet Devices 257.68' 0 X 4.00, C= 2.62 Head (feet) 0.00 0.50 Width (feet) 1.75 1.75 0 2,618 6,125 Primary OutFlow Max=6.07 cfs@ 12.11 hrs HW=258.09' (Free Discharge) 'L--t=o (Weir Controls 6.07 cfs@ 2.1 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 25-Year Rainfal/=8.40" Prepared by {enter your company name here} HydroCAD® 7 .10 sin 003394 © 2005 HydroCAD Software Solutions LLC Page 8 2/2/2009 Pond P1: Pond 1 Hydrograph 10 9.78 cfs 9 Inflow Area=1.000 ac 8 Peak Elev=258.09' 7 3: .2 5 LL 4 3 2 0 0 258.18 258.16 258.14 258.12 258.1 258.08 258.06 258.04 258.02 ~ 258 0 t7.98 _ 7.96 ~57.94 j 57.92 ~257.9 ~57.88 57.86 257.84 257.82 257.8 257.78 257.76 257.74 257.72 257.7 257.68 0 Storage=4,318 cf 6.12 cfs 2 3 4 5 6 7 8 9 10 11 12 13 Time (hours) Pond P1 : Pond 1 Stage-Area-Storage Surface/Horizontal/Wetted Area (sq-ft) 2,000 4,000 6,qoo 8,000 10,000 12,000 14,000 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 Storage (cubic-feet) -Inflow -Primary 14 15 16 17 18 19 20 16,000 18,000 20,000 22,000 -Surface -Storage 4,500 5,000 5,500 6,000 HydroCAD -. Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type JI 24-hr 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P1: Pond 1 for 50-Year event 0.655 af Page 9 2/2/2009 Outflow = Primary = 1.000 ac, Inflow Depth> 7.86" 11.58 cfs@ 12.01 hrs, Volume= 7.16 cfs@ 12.11 hrs, Volume= 7.16 cfs@ 12.11 hrs, Volume= 0.654 af, Atten= 38%, Lag= 6.2 min 0.654 af Routing by Stor-lnd method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.14'@ 12.11 hrs Surf.Area= 21,237 sf Storage= 5,258 cf Plug-Flow detention time=7.8 min calculated for 0.652 af (100% of inflow) Center-of-Mass det. time=7.4 min ( 750.3 -742.9) Volume Invert Avail.Storage Storage Description #1 257.68' 6, 125 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation (feet) Surf.Area (sq-ft) Inc.Store (cubic-feet) Cum.Store (cubic-feet) 257.68 258.00 258.18 Device Routing #1 Primary 0 16,360 22,611 0 2,618 3,507 Invert Outlet Devices 257.68' 0 X 4.00, C= 2.62 Head (feet) 0.00 0.50 Width (feet) 1. 75 1. 75 0 2,618 6,125 Primary OutFlow Max=7.11 cfs@ 12.11 hrs HW=258.14' (Free Discharge) ~1=0 (Weir Controls 7.11 cfs@ 2.2 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Page 10 21212009 Pond P1: Pond 1 Hydrograph 12 11 .56cfs -Inflow -Primary 11 Inflow Area=1.000 ac 10 9 Peak Elev=258.14' 6 Storage=5,258 cf 7.16cfs ~ 7 ~ ;: 6 0 ii: 5 4 3 2 0 0 2 3 4 5 6 7 6 9 10 11 12 13 14 15 16 17 16 19 20 Time (hours) Pond P1: Pond 1 Stage-Area-Storage Surface/Horizontal/Wetted Area (sq-ft) 0 2,000 4,000 6,000 6,000 10,000 12,000 14,000 16,000 16,000 20,000 22,000 -Surface 256.16 256.16 -Storage 256.14 256.12 256.1 256.06 256.06 256.04 256.02 -256 t7.96 7.96 !l57.94 ~57.92 ~257.9 ~57.66 57.66 257.64 257.62 257.6 257.76 257.76 257.74 257.72 257.7 257.66 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 Storage (cubic-feet) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 100-Year Rainfal/=11.00" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P1: Pond 1 for 100-Year event 0.748 af Page 11 2/2/2009 Outflow = Primary = 1.000 ac, Inflow Depth> 8.98" 13.12 cfs@ 12.01 hrs, Volume= 8.05 cfs @ 12.11 hrs, Volume= 8.05 cfs @ 12.11 hrs, Volume= 0.747 af, Atten= 39%, Lag= 6.3 min 0.747 af Routing by Star-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.18'@ 12.11 hrs Surf.Area= 22,528 sf Storage= 6,071 cf Plug-Flow detention time=8.1 min calculated for 0.746 af (100% of inflow) Center-of-Mass det. time= 7.7 min ( 747.5 -739.8) Volume Invert Avail.Storage Storage Description #1 257.68' 6, 125 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation (feet) Surf.Area (sq-ft) Inc.Store (cubic-feet) Cum.Store (cubic-feet) 257.68 258.00 258.18 Device Routing #1 Primary 0 16,360 22,611 0 2,618 3,507 Invert Outlet Devices 257.68' 0 X 4.00, C= 2.62 Head (feet) 0.00 0.50 Width (feet) 1. 75 1. 75 0 2,618 6,125 Primary OutFlow Max=7.98 cfs@ 12.11 hrs HW=258.17' (Free Discharge) "t-1=0 (Weir Controls 7.98 cfs@ 2.3 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 1 Crossroads-TR20 B-020209 Type II 24-hr 100-Year Rainfall= 11 . 00" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Pond P1: Pond 1 Hydrograph 14 13.12cfs 13 12 Inflow A rea=1.000 ac 11 Pea k Elev=258.18' 10 9 Storage=6,071 cf 8.05 cfs i: 8 .e ~ 7 0 u:: 6 5 4 3 2 0 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Time (hours) Pond P1: Pond 1 Stage-Area-Storage Surface/Horizontal/Wetted Area (sq-ft) 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 258.18 258.16 258.14 258.12 258.1 258.08 258.06 258.04 258.02 ~ 258 t7.98 7.96 lf57.94 j57.92 ~257.9 ~57.88 57.86 257.84 257.82 257.8 257.78 257.76 257.74 257.72 257.7 257.68 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 Storage (cubic-feet) 16 17 18 18,000 20,000 5,000 5,500 19 20 22,000 6,000 Page 12 21212009 -Inflow -Primary -Surface -Storage HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 2-Year Rainfal/=4. 50" Prepared by {enter your company name here} HydroCAD® 7.1 0 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P2: Pond 2 for 2-Year event 0.234 af Page 1 21212009 Outflow = Primary = 0.940 ac, Inflow Depth > 2.99" 4.41 cfs @ 12.01 hrs, Volume= 3.58 cfs @ 12.08 hrs, Volume= 3.58 cfs @ 12.08 hrs, Volume= 0.229 af, Atten= 19%, Lag= 3.9 min 0.229 af Routing by Star-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 256. 71 '@ 12.08 hrs Surf.Area= 293 sf Storage= 1,394 cf Plug-Flow detention time=20.8 min calculated for 0.229 af (98% of inflow) Center-of-Mass det. time= 12.1 min ( 777.9 -765.8) Volume Invert Avail.Storage Storage Description #1 #2 #3 Elevation {feet} 257.84 258.34 258.50 Elevation {feet} 254.50 258.68 254.50' 257.84' 254.50' Surf.Area {sg-ft} 0 15,404 16,000 Surf.Area {sg-ft} 16 16 Device Routing Invert #1 Primary 254.99' 1, 165 cf 24.0"D x 185.38'L Drainage Pipe Storage S= 0.0025 '/' x 2 6,363 cf Parking Storage (Prismatic) Listed below (Recalc) 468 cf J-Box Storage (Prismatic) Listed below (Recalc) x 7 7,996 cf Total Available Storage Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 3,851 3,851 2,512 6,363 Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 67 67 Outlet Devices 11.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=3.52 cfs@ 12.08 hrs HW=256.67' (Free Discharge) L1=0rifice/Grate (Orifice Controls 3.52 cfs@ 5.3 fps) HydroCAD -Proposed Conditions Pond Ca lculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 2-Year Rainfal/=4.50" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 4 3 2 Pond P2: Pond 2 Hydrograph Inflow Area=0.940 ac Peak Elev=256. 71' Storage=1,394 cf 4.41 cfs 3.58 cfs o..J,,.......,............,.........,............,.,..........,....,......,......,..-....... ~;;;::;:::::::::......,.......,....,.....:::::::;:;;;:::;:;:;:;::;::;:;:;:;::;:;:;:;:;:;:;::;:;:;:;:;;;:j 258 ~ 257 ~ 256 255 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond P2: Pond 2 Stage-Area-Storage + 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 Storage (cubic-feet) Page 2 21212009 -Inflow -Primary I-Storage. HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 5-Year Rainfal/=6.20" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P2: Pond 2 for 5-Yearevent 0.354 at Page 3 21212009 Outflow = Primary = 0.940 ac, Inflow Depth > 4.52" 6.51 cfs@ 12.01 hrs, Volume= 5.07cfs@ 12.10hrs, Volume= 5.07 cfs@ 12.10 hrs, Volume= 0.349 at, Atten= 22%, Lag= 5.4 min 0.349 at Routing by Star-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 257.99'@ 12.10 hrs Surf.Area= 4,804 sf Storage= 1,913 cf Plug-Flow detention time= 17.0 min calculated for 0.348 at (98% of inflow) Center-of-Mass det. time= 10.7 min ( 766.6 -756.0) Volume Invert Avail.Storage Storage Description #1 #2 #3 Elevation {feet} 257.84 258.34 258.50 Elevation {feet} 254.50 258.68 254.50' 257.84' 254.50' Surf.Area {sg-ft} 0 15,404 16,000 Surf.Area {sg-ft} 16 16 Device Routing Invert #1 Primary 254.99' 1, 165 cf 24.0"0 x 185.38'L Drainage Pipe Storage S= 0.0025 '/' x 2 6,363 cf Parking Storage (Prismatic) Listed below (Recalc) 468 cf J-Box Storage (Prismatic) Listed below (Recalc) x 7 7,996 cf Total Available Storage Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 3,851 3,851 2,512 6,363 Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 67 67 Outlet Devices 11.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=5.07 cfs@ 12.10 hrs HW=257.99' (Free Discharge) L1=0rifice/Grate (Orifice Controls 5.07 cfs@ 7.7 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 5-Year Rainfal/=6.20" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Pond P2: Pond 2 Hydrograph 7 6 Inflow Area=0.940 ac Peak Elev=257 .99' 5.07cfs 5 Storage=1,913 cf 2 o.:L. .................................................. ---...-..... is:;::;:;:;::;;:;;:;::;:::::;::::::.._ __ _:::===::::::::::;:;:;:;::;::;:;:;::;:;:;:;:;:;:;:J 258 ~ 257 !. c: .5! ! iij 256 255 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond P2: Pond 2 Stage-Area-Storage 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 Storage (cubic-feet) Page4 21212009 -Inflow -Primary 1-storagel HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area = Inflow = Outflow = Primary = Pond P2: Pond 2 0.940 ac, Inflow Depth> 5.62" for 7.98 cfs@ 12.01 hrs, Volume= 5.18 cfs @ 12.10 hrs, Volume= 5.18 cfs @ 12.1 O hrs, Volume= 10-Year event 0.441 af 0.435 af, Atten= 35%, 0.435 af Routing by Stor-lnd method , Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.11'@ 12.10 hrs Surf.Area= 8,389 sf Storage= 2,681 cf Plug-Flow detention time= 15. 7 min calculated for 0.434 af (98% of inflow) Center-of-Mass det. time= 10.3 min ( 761.1 -750.8 ) Volume Invert Avail.Storage Storage Description Page 5 21212009 Lag= 5.7 min #1 #2 #3 254.50' 257.84' 254.50' 1, 165 cf 24.0"D x 185.38'L Drainage Pipe Storage S= 0.0025 '/' x 2 6,363 cf Parking Storage (Prismatic) Listed below (Recalc) 468 cf J-6ox Storage (Prismatic) Listed below (Recalc) x 7 7,996 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store {feet} {sg-ft} {cubic-feet} {cubic-feet} 257.84 0 0 0 258.34 15,404 3,851 3,851 258.50 16,000 2,512 6,363 Elevation Surf.Area Inc.Store Cum.Store {feet} {sg-ft} {cubic-feet} {cubic-feet} 254.50 16 0 0 258.68 16 67 67 Device Routing Invert Outlet Devices #1 Primary 254.99' 11.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=5.18 cfs@ 12.1 O hrs HW=258.11' (Free Discharge) "t_1=0rifice/Grate (Orifice Controls 5.18 cfs@ 7.9 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 10-Year Rainfal/=7.40" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Pond P2: Pond 2 Hydrograph 7.98 cfs 8 Inflow Area=0.940 ac 7 Peak Elev=258.11' 6 Storage=2,681 cf 5.18 cfs 3 2 o.:l...........,..,.,.....,.. ................. ~--....,._,.~;:;:;:;;:;:;:;::;:::::;:::::... .................. ..:::::;:;:;;:;;:;:;:;:;::;:;:;:;:;;:;:;:;:;:;;:j~ 258 ~ 257 ~ c .2 "(Q > QI iii 256 255 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond P2: Pond 2 Stage-Area-Storage + 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 Storage (cubic-feet) Page 6 2/2/2009 -Inflow -Primary I-Storage I HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 25-Year Rainfall=B.40" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P2: Pond 2 for 25-Year event 0.513 af Page 7 21212009 Outflow = Primary = 0.940 ac, Inflow Depth > 6.55" 9.19 cfs@ 12.01 hrs, Volume= 5.27 cfs @ 12.12 hrs, Volume= 5.27 cfs @ 12.12 hrs, Volume= 0.507 af, Atten= 43%, Lag= 6. 7 min 0.507 af Routing by Star-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.19'@ 12.12 hrs Surf.Area= 11,036 sf Storage= 3,515 cf Plug-Flow detention time= 15.3 min calculated for 0.507 af (99% of inflow) Center-of-Mass det. time= 10.5 min ( 757.6 -747.2) Volume Invert Avail.Storage Storage Description #1 #2 #3 Elevation {feet} 257.84 258.34 258.50 Elevation {feet} 254.50 258.68 254.50' 257.84' 254.50' Surf.Area {sg-ft} 0 15,404 16,000 Surf.Area {sg-ft} 16 16 Device Routing Invert #1 Primary 254.99' 1, 165 cf 24.0"D x 185.38'L Drainage Pipe Storage S= 0.0025 '/' x 2 6,363 cf Parking Storage (Prismatic) Listed below (Recalc) 468 cf J-Box Storage (Prismatic) Listed below (Recalc) x 7 7,996 cf Total Available Storage Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 3,851 3,851 2,512 6,363 Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 67 67 Outlet Devices 11.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=5.26 cfs@ 12.12 hrs HW=258.19' (Free Discharge) L1=0rifice/Grate (Orifice Controls 5.26 cfs@ 8.0 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 25-Year Rainfal/=8.40" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC .!! ~ ~ 0 ii: 10 9 8 7 6 5 4 3 2 Pond P2: Pond 2 Hydrograph Inflow Area=0.940 ac Peak Elev=258.19' Storage=3,515 cf 9.19cfs 5.27 cfs o-L......,..,..... .................... ......,_.._.'""'""'~:;:;:;:;:;;;:;::;::;::;:;:;:;:;:::::...,.,.,.....,~:::;::;:;:;:;:;::::;:;:;:;:;:;::;:::;:;:;::;:;;;:;:;:;:;:;:;:) 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond P2: Pond 2 Stage-Area-Storage 258 ~ 257 ~ c .!2 Oi > "' iii 256 255 0 1,000 + 2,000 3,000 4,000 5,000 6,000 7,000 Storage (cubic-feet) Page 8 21212009 -Inflow -Primary 1-storagei HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 8-020209 Type II 24-/1r 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} HydroCAD® 7 .1 0 sin 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P2: Pond 2 for 50-Year event 0.615 af Page 9 21212009 Outflow = Primary = 0.940 ac, Inflow Depth> 7.86" 10.89 cfs@ 12.01 hrs, Volume= 5.36 cfs@ 12.14 hrs, Volume= 5.36 cfs @ 12.14 hrs, Volume= 0.609 at, Atten= 51 %, Lag= 7.8 min 0.609 at Routing by Ster-Ind method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.29'@ 12.14 hrs Surf.Area= 14,012 sf Storage= 4,725 cf Plug-Flow detention time= 15.0 min calculated for 0.609 at (99% of inflow) Center-of-Mass det. time= 10.8 min ( 753.7 -742.9) Volume Invert Avail.Storage Storage Description #1 #2 #3 Elevation {feet} 257.84 258.34 258.50 Elevation {feet} 254.50 258.68 254.50' 257.84' 254.50' Surf.Area {sg-ft} 0 15,404 16,000 Surf.Area {sg-ft} 16 16 Device Routing Invert #1 Primary 254.99' 1, 165 cf 24.0"D x 185.38'L Drainage Pipe Storage S= 0.0025 '/' x 2 6,363 cf Parking Storage (Prismatic) Listed below (Recalc) 468 cf J-Box Storage (Prismatic) Listed below (Recalc) x 7 7,996 cf Total Available Storage Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 3,851 3,851 2,512 6,363 Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 67 67 Outlet Devices 11.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=5.36 cfs@ 12.14 hrs HW=258.29' (Free Discharge) -t_1=0rifice/Grate (Orifice Controls 5.36 cfs @ 8.1 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type II 24-hr 50-Year Rainfal/=9. 80" Prepared by {enter your company name here} . HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 12 11 10 9 8 i 7 .e. ~ 6 0 ii: 5 4 3 2 Pond P2: Pond 2 . Hydrograph Inflow Area=0.940 ac Peak Elev=258.29' Storage=4, 725 cf 10.89 cfs 5.36 cfs o.l.-......,..,..,.,.,..,.,........,~_...~ .... ~:;::;:;:;;;:;:;:::;:;::;::;:;::;:;::;::;:.,..,..,..,.,..___,.....;:::;:;:;:;:;:;:;:;::;:;::;:;:;:;:;:;:;:;:;;:;:;::;:;;:;....i 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) 258 ~ 257 ~ c :8 .. > Cl> iii 256 255 0 1,000 2,000 Pond P2: Pond 2 Stage-Area-Storage 3,000 4,000 5,000 6,000 7,000 Storage (cubic-feet) Page 10 2/2/2009 -Inflow -Primary I-Storagel HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 B-020209 Type 1124-hr 100-Year Rainfal/=11.00" Prepared by {enter your company name here} HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Inflow Area= Inflow = Pond P2: Pond 2 for 100-Year event 0.703 af Page 11 21212009 Outflow = Primary = 0.940 ac, Inflow Depth > 8.98" 12.33 cfs @ 12.01 hrs, Volume= 5.43 cfs @ 12.15 hrs, Volume= 5.43 cfs @ 12.15 hrs, Volume= 0.697 af, Atten= 56%, Lag= 8.6 min 0.697 af Routing by Stor-lnd method, Time Span= 0.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 258.37'@ 12.15 hrs Surf.Area= 15,625 sf Storage= 5,903 cf Plug-Flow detention time= 15.1 min calculated for 0.695 af (99% of inflow) Center-of-Mass det. time= 11.3 min ( 751 .2 -739.8) Volume Invert Avail.Storage Storage Description #1 #2 #3 Elevation {feet} 257.84 258.34 258.50 Elevation {feet} 254.50 258.68 254.50' 257.84' 254.50' Surf.Area {sg-ft} 0 15,404 16,000 Surf.Area {sg-ft} 16 16 Device Routing Invert #1 Primary 254.99' 1, 165 cf 24.0"D x 185.38'L Drainage Pipe Storage S= 0.0025 '/' x 2 6,363 cf Parking Storage (Prismatic) Listed below (Recalc) 468 cf J-Box Storage (Prismatic) Listed below (Recalc) x 7 7,996 cf Total Available Storage Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 3,851 3,851 2,512 6,363 Inc.Store Cum.Store {cubic-feet} {cubic-feet} 0 0 67 67 Outlet Devices 11.0" Vert. Orifice/Grate C= 0.600 Primary OutFlow Max=5.43 cfs@ 12.15 hrs HW=258.37' (Free Discharge) L1=0rifice/Grate (Orifice Controls 5.43 cfs@ 8.2 fps) HydroCAD -Proposed Conditions Pond Calculations -Pond 2 Crossroads-TR20 8-020209 Type II 24-hr 100-Year Rainfal/=11.00" Prepared by {enter your company name here} HydroCAD® 7 .10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 13 12 11 10 9 5 4 3 2 Pond P2: Pond 2 Hydrograph Inflow Area=0.940 ac Peak Elev=258.37' Storage=5,903 cf 12.33 cfs o!..... .................. _,..,..._ __ ........ _.;;:;:;:;::;::;:;:;:;:=:==:::::::::~---=::::::::::::::;:;;;:=::;;:;::;:;::=o:;:;;::;::l 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Pond P2: Pond 2 Stage-Area-Storage 258- ~ 257 ~ c .2 -; > ., iii 256 255 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 Storage (cubic-feet) Page 12 2/2/2009 -Inflow -Primary 1-storage l Section 5.0 STORM DRAINAGE SYSTEM Texas Hydraulic System Culvert Design Creek Meadows-S5Pl 202-0359 Brazos County CulvertP3 P3 Shape: Circular Material: Concrete Span: 0.00 Rise: 1.50 Barrels: 1 Discharge Description 2YR 5YR lOYR 25YR 50YR lOOYR ft ft Q total (cfs) 2.39 2.90 3.26 3.72 4.20 4.39 *Backwater (BW = HW -TW -S·L) HW TW elevation elevation (ft) (ft) 254.27 253.45 254.38 253.47 254.45 253.53 254.53 253.56 254.61 253.58 254.64 253.60 Length(L): 50.00 ft Slope(S): 0.0070 n: 0.0120 Ke: 0.50 Entrance Type: Headwall I BW* V Q Inlet Ctl Outlet Ctl out over road HW depth HW depth (ft) (ft) ( cfs) (ft) (ft) 0.46 4.57 0.00 0.82 0.98 0.55 4.74 0.00 0.93 1.09 0.56 4.96 0.00 1.00 1.16 0.62 5.10 0.00 1.08 1.25 0.68 5.24 0.00 1.16 1.33 0.70 5.29 0.00 1.19 1.36 C:\USERS\USER\RME\PROJECTS\237-03-1 \ENGINE-I \0365TI RA.CL V 10/29/08 ., SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Engineering Firm Name and Address: Jurisdiction tzme Cot-l6u1..-r1"1~ EN {:;n "'1 r;:. E.il 5 City: Bryan p. 0. P-:>ox. '1 z s ~ )( College Station Cot..1..P-~e. 5'-rA'1.,tt)r-.J 1 lX. 778~2.. Date of Submittal: 10/20/c'C Lead Engineer's ~me and Contapt lnfo.(phone, e-mail, fax): ) Other: 12At0at.J A. e..-u.~1..-F, -1~-{479 -(Q9o-o~'2.0i Supporting Engineering I Consulting Firm(s): Other contacts: Developer I Owner I Aoolicant Information Developer I Applicant Name and Address: Phone and e-mail: T6'!C~ \4:S" \N\l'E:S>I MJZ.tSl ~. LLQ ~c.to:s ~~ DA~~. ~i.,'-c:=~ A'1•o...l l'K 17c'S"-IS Property Owner(s) if not Developer I Applicant (&address): Phone and e-mail: Project Identification Development Name: ~ '2o'=>~'2. l:>APS 12e-c A\L. CTi-Nt~ Is subject property a site project, a single-phase subdivision, or part of a multi-phase subdivision? ~, bl~'-~ 'Ptl f\S,E.. If multi-phase, subject property is phase of Legal description of subject property (phase) or Project Area: (see Section II, Paragraph B-3a) Lo-r '2 oF HAfl\@{ RoRo F-A&; $.; rfb(;::;il V I !::>I o N 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/A General Location of Project Area, or subject property (phase): ~.OF-OF-~I-Jo. ".3-o Af'r~x, )"}1 Jo/7JEL.'/ /...ocJ'(tFiD ON T"tfE NOttl+ tno 1..,F. ~ e>P 115 /tJ-fe(lS,fE,Of10J UJrfH S.J/.. JJo. ~ In City Limits? Extraterritorial Jurisdiction (acreage): Bryan: acres. Bryan: College Station: College Station: -z .ou, '1 acres. Acreage Outside ET J: Part 2 -Proiect Administration I Continued (page 2.2) Project Identification (continued) STORMWATER DESIGN GUIDELINES Effective February 2007 Page 3 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Roadways abutting or within Project Area or Abutting tracts, platted land, or built subject property: C=tt ~">) developments: \ ~"Pi~~-r .5~1fJ"G.s-~~ Loe.~ N r ~'-\... \JJ \rJ t:>WoC\>t.:::> £s.-r ~ Named Regulatory Watercourse(s) & Watershed(s): Tributary Basin(s): l) NrolPry\'\p.x:> ~~ or L ~-uga.~ ((l).t. c:::: Afl.:tee,~ C'2e..e:-~ Plat Information For Project or Subject Property (or Phase) Preliminary Plat File #: Final Plat File #: Date: t,/rz/ S'T Name: Status and Vol/Pg: t/ZZ. I Bl?;, If two plats, second name: File#: Status: Date: Zoning Information For Project or Subject Property (or Phase) Zoning Type: ~r Proposed? Case Code: Case Date 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? No 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. Nj~ Part 2 -Project Administration I Continued (page 2.3) Coordination For Project or Subject Property (or Phase) STORMWATER DESIGN GUIDELINES Effective February 2007 Page 4 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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? --r>c.""DOI 'fu..e.VV'\\1'"1\N"~ fi:>'l-'Pt2-1'11~ fl"'f Yes _L No c" t,,-..re.~ ""( . -- Coordination with Summarize need(s) & actions taken (include contacts & dates): T AMUS Needed? Yes --No _x:: Pennits 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 obiective in spaces below. Entity Permitted or Status of Actions (include dates) Approved? US Army Crops of Engineers No _L Yes - US Environmental Protection Agency No ./ Yes - Texas Commission on ::Sw f".:; 6->~mn"7~ 101 Cl:~e>J2-.~ Environmental Quality No --Yes.:/_ Brazos River Authority No _L_ Yes - Part 3 -Property Characteristics I Start (Page 3.1) Nature and Scope of Proposed Work STORMWATER DESIGN GUIDELINES Effective February 2007 Page 5 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Existing: Land proposed for development currently used, including extent of impervious cover? YAc-~Nl 4 utSCP-~1..oe£0 Site __ Redevelopment of one platted lot, or two or more adjoining platted lots. Development _L 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 lots, 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 lots. Development __ Construction of streets and utilities to serve one or more proposed lots on Project lands represented by pending plats. Site projects: 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 S\...st':11\..£ Ccm'\ m0(l.c. l fr\. . L.~1 'Df2.vE\..CA'V\1t.ft1 Co~l.'o~\t..s&r- Proeosed Or A l'B I 81'5 &CW. PT ~\1..01rS'1-c.ti A <o,lSC> 5Q.P"f Project ~\\..\:>\.-.lVr ~ fO<. 'fb-r~~CE:.~~f\rv\'fUJ( Is any work planned on land that is not platted If yes, explain: or on land for which platting is not pending? __j{No --Yes FEMA Floodplains Is any part of subject property abutting a Named Regulatory Watercourse I N y ~ (Section 11 , Paragraph B 1) or a tributary thereof? 0 --es -- Is any part of subject property in floodplain I No_ Yes _L_ Rate Map lc./ZC area of a FEMA-regulated watercourse? Encroachment(s) Encroachment purpose(s): _L_ Building site(s) __ Road crossing(s) into Floodplain areas planned? __ Utility crossing(s) __ Other (explain): No -- Yes_L 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. J NFaUrt,IHt 1)1'.} U~-0 F6t.. 7"H1 S. I>ruJ.11'f/Jt:;ni::_ ..S--&vP'f (//~.Bit~ ~ FF--fYIA Ft V2 W1 WI IJl'S '¥ ,, P-::::67'e.i£. ~A' I fk.o VI O;<:o B.'-f to CS cN' /Op 'I /oe . Part 3 -Property Characteristics I · Continued (Page 3.2) Hydrologic Attributes of Subject Property (or Phase) Has an earlier hydrologic analysis been done for larger area including subject property? STORMWATER DESIGN GUIDELINES Effective February 2007 Page 6 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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 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. / Yes Do existing topographic features on subject property store or detain runoff? ___!l_ No --Describe them (include approximate size, volume, outfall, model, etc). / Any known drainage or flooding problems in areas near subject property? __ No __..!l_ Yes Identify: {t+E. {)JtAJPwooo Commu1'1t'1'1 1-}ffs f4uq,nrw ~IVb-l~\JJU:::, iA.>J;: "?'o 'R.Jooo VTA-r~ Fv12~ CtHZ-~s. C~-D< .. Based on location of study property in a watershed, is Type 1 Detention (flood control) needed? (see Table B--1 in Appendix B) _L Detention not required. __ Detention is required. --Need must be evaluated. What decision has been reached? By whom? If the need for C1v1c.. laH Type 1 Detention How was determination made? must be evaluated: fi0or> &1 UD"( A=:<l. Fo£.rt'llC.o or l:;:,;:,-rererri' "'l!-0 T rJfrt l>e-r~t o,..J Wo 01-.c bri:. R.e.Qu, flEO, Part 3 -Prol!em Characteristics I Continued (Page 3.3) Hydrologic Attributes of Subject Property (or Phase) (continued) Does subject property straddle a Watershed or Basin divide? _L No --Yes If yes, describe splits below. In Part 4 describe design concept for handling this. Watershed or Basin STORMWATER DESIGN GUIDELINES Effective February 2007 Page 7 of26 I Larger acreage I Lesser acreage I I APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Above-Project Areas(Section II, Paragraph 83-a) Does Project Area (project or phase) receive runoff from upland areas? __ No Size(s) of area(s) in acres: 1) rv/.{oo 2) 3) 4) _{__Yes Flow Characteristics (each instance) (overland sheet, shallow concentrated, recognizable J concentrated section(s), small creek (non-regulatory), regulatory Watercourse or tributary); C nl}NtJ Gl..t "?.FDO ~t.../Y7olf/1 Tet '6.>7 A-t:-'1 , <fl ~ Flow determination: Outline hydrologic methods and assumptions: / J\ Cffp..-C--f\ vrz; Fio \JJ :PM A ~ cfi)C) ON EfJrt-1 /\{ erE¥LS ti\ CtJe-v(lorJ Ct.o«ir'Z. f-}-( D!VhJLI e, /Jwlff-"'/St~ '1) Does storm runoff drain from public easements or ROW onto or across subject property? ~ __ No _L Yes If yes, describe facilities in easement or ROW: 50' Vt!.lt1l'I~ ~fi.rV'I~ (Vz911 1 P =zss) i2 i ~ Are changes in runoff characteristics subject to change in future? Explain ~ UtJJ..\ l~.A--'1-P~Arf\l/k:r£ foNPl7tc:r-(5 UPbTfZ.E./rrYl /TrZE. Irr r> R . llfta;rl_ vt... 71 tn-Ace W..vF-A-'Ci?rvJUJ1 CoNrJt710l'J .s - Conveyance Pathways (Section II , Paragraph C2) Must runoff from study property drain across lower P,roperties before reaching a Regulatory Watercourse or tributary? No / Yes Describe length and characteristics of each conveyance pathway(s). Include ownership of property(ies ). r1tF-~ P6r(l...-t'1 I':;, AoJ-Ac.rur1 7"t> -n+£ .e-;;::.C;tU LJ970t0-/ t)J')tJ~ -(~ r:Oc.J-t Art...f oF-C11-e-rus Cerc=n<.. Part 3 -Pro~em Characteristics I Continued (Page 3.4) Hydrologic Attributes of Subject Property (or Phase) (continued) Conveyance Pathways (continued) Do drainage If yes, for what part of length? 5..0 % Created by? ,/ plat, or easements __ instrument. If instrument(s), describe their provisions. exist for any oart of 5c ' DIZA-1 ftlA-tAT-Ce.m-r STORMWATER DESIGN GUIDELINES Effective February 2007 Page 8 of26 ( l/'2. s<1' p z-ss) APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY pathway(s)? OPP...'?!T/C. -../-7o ?tr!. Co,.JFl-oFNU:::.. w/C/ffl-r11..~h C..~ 7i-fert.£ IJ~ /Vo l~fJ04.>Jw F-~~. No 7ves Pathway Areas Nearby Where runoff must cross lower properties, describe characteristics of abutting lower property(ies). (Existing watercourses? Easement or Consent aquired?) JtvfJ AYVJPDt T "'-'.'lb.rt~ rv1EA/\ft:>~ 7/W-OvGH-U"1aN'w~l:J f7tt.ofU7'-f cHM t:, /H1C= fioooPcAuJ or;-O:J.fl,-ru_.~ C'2.F-P..l.... of.. /}£r.rlt-CkiS1 -Co 7"(-f~ Wr,.Sr::>vJoV~ ~ ~Pt vr ~to,.!\. Describe any built or improved drainage facilities existing near the property (culverts, bridges, lined channels, buried conduit, swales, detention ponds, etc). , lmmw1f'l11ei.t ()f'.!7~ -rtf'll41~14 5-8-A~L '1 '~1' f?ox: lvc..V'LXL-r • / fVl.YVltvC>I fi 7 F-A.-...f ~c,;.lN&712~ Tf"IC'(4i;. IS ft- -'?r#~c,e. fbA~ {;u.Vrvt;-r C'2.s::£>~1NGr 9H 3'U . Drainage t-=-~~-::-:~~~-,---~~~~~~~-,--~~~~~~~~~~~--i Facilities Do any of these have hydrologic or hydraulic influence on proposed stormwater design? __ No _L Yes If yes, explain: (e+e fh c.-~ l'Y1ooJ:.L. ;;;;fooc,,O 71'9tLJE" 1,.s-z0 Acc..ovw-t ~AcKW/t-11Zt(. 1mf'Ae.-rs tPr -n-1£ 5//?:>o ~1,.Jlk::f£ t' {k~'?f ,.J Vr - Part 4 -Drainage Conce~t and Design Parameters I 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. STORMWATER DESIGN GUIDELINES Effective February 2007 Page 9 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY {}f>t,.ltNO Ft.ow$ frer:i.. /tcc.~C/t7~ /IS ?f/E. l?,c1:,71"'fir 1/fl.ltttJ~ Ct1 llNN"F--1-• Discharge(s) To Lower Property(ies) (Section II, Paragraph E1) Does project i?de drainage features (existing or future) proposed to become public via platting? No Yes Separate Instrument? No Yes Per Guidelines reference above, how will Establishing Easements (Scenario 1) runoff be discharged to neighboring =:z Pre-development Release (Scenario 2) property(ies)? 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# ) 1?V!-ltJN~ btvc'I 7/JS.-f tz.trf cu-.J VSLC..t.. ~ Ac <..<=>/\1ot0rt'71CO 13'-f Yl1~ 6P- ~ff'/& 6vfl.P-A-Ce · ~l)(ZA~ of IF .A V~·CJ-IH!:1~fl. UN~£~"" ~ IN/k..:tr:G. v'-/s.7'~~. 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. Part 4 -Drainage Conce(!t and Design Parameters I Continued (Page 4.2) Stormwater Management Concept (continued) Within Project Area Of Multi-Phase Project Will project result Identify gaining Basins or Watersheds and acres shifting: in shifting runoff between Basins or between STORMWATER DESIGN GUIDELINES Effective February 2007 Page 10 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Watersheds? _LNo __ Yes What design and mitigation is used to compensate for increased runoff from gaining basin or watershed? How will runoff from Project Area be mitigated to pre- development conditions? Select any or all of 1, 2, and/or 3, and explain below. 1. __ With facility(ies) involving other development projects. 2. ~ Establishing features to serve overall Project Area. 3. __ On phase (or site) project basis within Project Area. 1. Shared facility (type & location of facility; design drainage area served; relationship to size of Project Area): (Attached Exhibit# · r · · --. _ _ 2. For Overall Project Area (type & location of facilities): (Attached Exhibit# ) ?" P/€./r1NA&r!C-&!d01 3. By phase (or site) project: Describe planned mitigation measures for phases (or sites) in subsequent questions of this Part. ~­-0 Q) Ul c Q) iii >-a: Ul c Cl "iii Q) 0 Oz Are aquatic echosystems proposed? __ No project(s)? __ Yes In which phase(s) or Are other Best Management Practices for reducing storrnwater pollutants proposed? __ No __ Yes Summarize type of BMP and extent of use: m 1--------------------------------1 ·UJ~a. I If design of any runoff-handling facilities deviate from provisions of B-CS Technical Specifications, check type facility(ies) and explain in later questions. __ Detention elements __ Conduit elements __ Channel features __ Swales __ Ditches __ Inlets __ Valley gutters __ Outfalls __ Culvert features __ Bridges Other Part 4 -Drainage ConceRt and Design Parameters I Continued (Page 4.3) Stormwater Management Concept (continued) Within Project Area Of Multi-Phase Project (continued) Will Project Area include bridge(s) or culvert(s)? _/__No --Yes Identify type and general size and In which phase(s). STORMWATER DESIGN GUIDELINES Effective February 2007 Page 11 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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): ~-t~1"14 ~IL-/?"'( VJ( t.L.. Ac.Q,vJ~7~ U1-Tt rYIM/€... T7£.Vet.0f'm1t.tJ1 FiOt.>1 Coµt:>r7<or.JS> cf-WJ L-<. ~ lfN/tc,,'(Z-t00 Irr / N"CFDtLp'Y'I Co f'l D / 71 o NS • Within Or Serving Subject Property (Phase, or Site) If property part of larger Project Area, is design in substantial conformance with earlier analysis and report for larger area? __ Yes No, then summarize the difference(s): N/A Identify whether each of the types of drainage features listed below are included, extent of use, and general characteristics. .0 Ill .... cu a~ >-I ..c cu .... Ill "§: Ill cu .... :t: cu ::I 0 ~~zl cu c .... nl <{ Typical shape? I Surfaces? Steepest side slopes: Usual front slopes: Usual back slopes: Flow line slopes: least ___ _ Typical distance from travelway: typical greatest. ___ _ (Attached Exhibit # ) Are longitudinal culvert ends in compliance with B-CS Standard Specifications? ___ Yes No, then explain: At intersections or otherwise, do valley gutters cross arterial or collector streets? ___ No __ Yes If yes explain: Are valley gutters proposed to cross any street away from an intersection? __ No __ Yes Explain: (number of locations?) Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.4) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) e a; Gutter line slopes: Least Usual Greatest ::I :t: ~ Are inlets recessed on arterial and collector streets? Yes No If "no", 0 ::I -c -- --~ Cl cu identify where and why. "t:I Ill - c ::I ~ IU STORMWATER DESIGN GUIDELINES Effective February 2007 Page 12 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Will inlets capture 10-year design stormflow to prevent flooding of intersections (arterial with arterial or collector)? --Yes --No If no, explain where and why not. Will inlet size and placement prevent exceeding allowable water spread for 10-year design storm throughout site (or phase)? --Yes --No If no, explain. Sag curves: Are inlets placed at low points? --Yes --No Are inlets and conduit sized to prevent 100-year stormflow from ponding at greater than 24 inches? --Yes --No Explain "no" answers. Will 100-yr stormflow be contained in combination of ROW and buried conduit on whole length of all streets? --Yes --No If no, describe where and why. Do designs for curb, gutter, and inlets comply with 8-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. <'-· "'O Pipe runs between system I Typical Q) U) Longest U) Q) access points (feet): :::J >- !1 Are junction boxes used at each bend? --Yes --No If not, explain where and why. U) c: -~~ "'O I E .... Least amount that hydraulic 0 Are downstream soffits at or below upstream soffits? Cii .!!! Yes No __ If not, explain where and why: grade line is below gutter line --(system-wide): Part 4 -Drainage Conceet and Design Parameters I Continued (Page 4.5) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or.Site) (continued) Q) Q) ' Describe watercourse(s), or system(s) receiving system discharge(s) below 5' ni :!2 ~ ~ (include design discharge velocity, and angle between converging flow lines). ~ .... > ltl 0. -0. .... ;rg 1) Watercourse (or system), velocity, and angle? s Q) 0.. ~ (/)...,. I :::J 4-1?? Ff5 tO ~ c: ~ I 0 V/llNArll~ TrZ-1.eo-rM>/ C)o i-0 .C: I -U) I STORMWATER DESIGN GUIDELINES Effective February 2007 Page 13 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 2) Watercourse (or system), velocity, and angle? 3) Watercourse (or system), velocity, and angle? For each outfall above, what measures are taken to prevent erosion or scour of receiving and all facilities at juncture? 1) 2) 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): C'-· .!!? QJ ~ rn ..... QJ Flow line slopes (minimum and maximum): rn >-c ~ I ~o rnz Outfall characteristics for each (velocity, convergent angle, & end treatment). ~ rn QJ ~ Will 100-year design storm runoff be contained within easement(s) or platted drainage ROW in all instances? --Yes --No If "no" explain: Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.6) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) ,, ~ ~ Are roadside ditches used? __LNo __ Yes If so, provide the following: ~ QJ "fi Is 25-year flow contained with 6 inches of freeboard throughout? __ Yes --No 0 ~ Are top of banks separated from road shoulders 2 feet or more? _· _Yes --No tl:'. 0 Are all ditch sections trapezoidal and at least 1.5 feet deep? Yes No ---- STORMWATER DESIGN GUIDELINES Effective February 2007 Page 14 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY For any "no" answers provide location(s) and explain: If conduit is beneath a swale, provide the following information (each instance). Instance 1 Describe general location, approximate length: II) Q) >- lw Is 100-year design flow contained in conduit/swale combination? --Yes --No If "no" explain: c 0 Ill z Ui Space for 100-year storm flow? ROW Easement Width \I~ Swale Surface type, minimum Conduit Type and size, minimum and maximum ~ and maximum slopes: slopes, design storm: C'-· =o II) Qi "'C Ill c >-Inlets Describe how conduit is loaded (from streets/storm drains, inlets by type): c Ill c ..c Ill 0 L. c J2 Q) c a. 0 0 :;:; Access Describe how maintenance access is provided (to swale, into conduit): -Ill 0 E ::J L. ~ J2 .s .S: Q) "'C E Instance 2 Describe general location, approximate length: Q) Ill II) II) ::J II) Q) c "'C .Q ·:;;; Is 100-year design flow contained in conduit/swale combination? Yes No iii 0 ----L. If "no" explain: c a. :0 a; E Q) 0 ..c Space for 100-year storm flow? ROW Easement Width 0 II) ..... Q) Swale Surface type, minimum Conduit Type and size, minimum and maximum ::J iii "'C L. and maximum slopes: slopes, design storm: c Ill 0 a. 0 Q) --II) Q) Inlets Describe how conduit is loaded (from streets/storm drains, inlets by type): iii c ;: ~ II) Q) L. <{ Access Describe how maintenance access is provided (to swale, into conduit): Part 4 -Drainage ConceRt and Design Parameters I Continued (Page 4. 7) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) . "'C If "yes" provide the following information for each instance: II) Q) Q) ·-Instance 1 Describe general location, approximate length, surfacing: iii :; :; ;: .0 , II) :J I -0 j = ..c j ~j STORMWATER DESIGN GUIDELINES Effective February 2007 Page 15 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Is 100-year design flow contained in swale? --Yes --No Is swale wholly within drainage ROW? --Yes --No Explain "no" answers: Access Describe how maintenance access is provide: Instance 2 Describe general location, approximate length, surfacing: Is 100-year design flow contained in swale? --Yes --No Is swale wholly within drainage ROW? __ Yes --No Explain "no" answers: Access Describe how maintenance access is provided: Instance 31 41 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 ---- C'-shaped, see "Swales" in this Part. If creating side banks, provide information below. "C .!: cu Will design replicate natural channel? Yes No If "no", for each instance "' Ill 0 ------Q. Q. describe section shape & area, flow line slope (min. & max.), surfaces, and 100-year 0 x ..... w design flow, and amount of freeboard: Q. .!!? "' Instance 1: cu c: >-cu E I cu > 0 Instance 2: ..... Q. E o ·-z ]\I Instance 3: (.) Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.8) Stonnwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Existing channels (small creeks): Are these used? --No _Jt:_ Yes "' c: ' If "yes" provide the information below. -cu Will small creeks and their floodplains remain undisturbed? __ Yes v ~ E No How C: CU I many disturbance instances? Identify each planned location: Ill > ~ ..C: 0 I (.) 0.. I ..§..; STORMWATER DESIGN GUIDELINES Effective February 2007 Page 16 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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. 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 and data. Is full report submitted? Yes --No If "no" explain: All Proposed Channel Work: For all proposed channel work, provide infonnation 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 I easements sized to contain channel and required maintenance space? --Yes __ No If not, identify location(s) and explain: Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.9) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) How many facilities for subject property project? '2-For each provide info. below. c For each dry-type facilitiy: Facility 1 Facility 2 0 ;; "' /.oo o.ct'/ qt.loo c Q) Acres served & design volume + 10% (1?600 Q) +:: ( 4>= 100-yr volume: free flow & plugged ~7 qr/83 q'{O f> 0 l6 (,500 Q) LL !7· "'/'( (e. Z.?;J t;.o'{ t/>.tS-.... Design discharge (10 yr & 25 yr) <( c Spillway crest at 100-yr WSE? ---1C:'_ yes no v/ yes no ---- STORMWATER DESIGN GUIDELINES Effective February 2007 Page 17 of 2.6 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY I Berms 6 inches above plugged WSE? I __IL_ yes --no l ~yes --no Explain any "no" answers: For each facility what is 25-yr design Q , and design of outlet structure? Facility 1: ~.23 GP-=.-~--eg c.7ANGru~..Z.. WF-L'fZ_S Facility 2: lR· Is-h -/z''¢ Vee-rr ~ O f!./ FAC£. Do outlets and spillways discharge into a public facility in easement or ROW? Facility 1: c/ Yes --No Facility 2: V Yes --No If "no· explain: For each, what is velocity of 25-yr design discharge at outlet? & at spillway? Facility 1: IJ/Rt-& IO/A-Facility 2: :J'.'2 Ff?& j!2: Are energy dissipation measures used? __ No /Yes Describe type and location: 'f:ot:. lC::. f2rP-~rP f'o N C.~-rfZ- For each, is spillway surface treatment other than concrete? Yes or no, and describe: Facility 1: '!Zoct~ /21P-~ Facility 2: re~ For each, what measures are taken to prevent erosion or scour at receiving facility? Facility 1: N/A Facility 2: fJ /A If berms are used give heights, slopes and surface treatments of sides. Facility 1: /.J fA Facility 2: 1-1/,4 Part 4 -Drainage Conceet and Design Parameters I Continued (Page 4.10) Storrnwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Do structures comply with B-CS Specifications? ~r no, and explain if "no": Ul ~ Facility 1; == u 0 Q) m ::i LL c c :z:; Facility 2: 0 c ~o c 0 Q) --Q) 0 For additional facilities provide all same information on a separate sheet. STORMWATER DESIGN GUIDELINES Effective February 2007 Page 18 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX ~· Ill C> c "iii Ill e APPENDIX D -TECHNICAL DESIGN SUMMARY Are parking areas to be used for detention? No maximum depth due to required design storm~ __ Yes What is Roadside Ditches: Will culverts serve access driveways at roadside ditches? __ No _!L_ Yes If "yes", provide information in next two boxes. Will 25-yr. flow pass without flowing over driveway in all cases? ---~::::Yes Without causing flowing or standing water on public roadway? ____:::::_Yes Designs & materials comply with 8-CS Technical Specifications? ~Yes Explain any "no" answers: __ No __ No __ No Are culverts parallel to public roadway alignment? _L Yes __ No Explain: 0 Ill :f'\a._ ~,t--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-----1 Creeks at Private Drives: Do private driveways, drives, or streets cross drainage iii ways that serve Above-Project areas or are in public easements/ ROW? "O 0 <1> z __ No __ Yes If "yes" provide information below . .!!?~ I L.. How many instances? Describe location and provide information below. ~ Location 1 : :; 0 ~ <( Location 2: Location 3: For each location enter value for: 2 Design year passing without toping travelway? Water depth on travelway at 25-year flow? Water depth on travelway at 100-year flow? For more instances describe location and same information on separate sheet. 3 Part 4 -Drainage ConceRt and Design Parameters I Continued (Page 4.11) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) 0 Named Reaulatorv Watercourses l& Tributaries\: Are culverts proposed on these Ill = facilities? _1L._ No __ Yes, then provide full report documenting assumptions, t:: .0 <I> ::J criteria, analysis, computer programs, and study findings that support proposed > a. :; .... 0 111 design(s). Is report provided? __ Yes __ No If "no", explain: <I> -0 L.. <I> <( Ill ::J STORMWATER DESIGN GUIDELINES Effective February 2007 Page 19 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Arterial or Major Collector Streets: Will culverts serve these types of roadways? -2No Yes How many instances? For each identify the location and provide the information below. Instance 1: Instance 2: Instance 3: Yes or No for the 100-year design flow: 1 2 3 Headwater WSE 1 foot below lowest curb top? Spread of headwater within ROW or easement? Is velocity limited per conditions (Table C-11)? Explain any "no" answer(s): Minor Collector or Local Streets: Will culverts serve these types of streets? VNo --Yes How many instances? for each identify the location and provide the information below: Instance 1: Instance 2: Instance 3: For each instance enter value, or "yes" I "no" for: 1 2 3 Design yr. headwater WSE 1 ft. below curb top? 100-yr. max. depth at street crown 2 feet or less? Product of velocity (fps) & depth at crown (ft)=? Is velocity limited per conditions (Table C-11)? ' Limit of down stream analysis (feet)? Explain any "no" answers: Part 4 -Drainage ConceQt and Design Parameters I 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 rn 'O ditch intersects) provide information requested in next eight boxes. t: G) Do culverts and travelways intersect at 90 degrees? Yes No If not, v E -- -- ~ .. identify location(s) and intersect angle(s), and justify the design(s): ::I c CJ 0 ~ STORMWATER DESIGN GUIDELINES Effective February 2007 Page 20 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Does drainage way alignment change within or near limits of culvert and surfaced approaches thereto? __ No --Yes If "yes" identify location(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 location(s), describe outfall design treatment(s): Is scour/erosion protection provided to ensure long term stability of culvert structural 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 location(s) and mitigation measures: Are all culvert designs and materials in compliance with 8-CS Tech. Specifications? --Yes --No If not, explain in Special Design Section of this Part. Part 4 -Drainage Conce~t and Design Parameters I 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)? Iii Gr O> ::!;:! OJ What drainage way(s) is to be crossed? STORMINATER DESIGN GUIDELINES Effective February 2007 Page 21 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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 iii Plan (SW3P) :J 0 established for .... project construction? Q) ~ --No --Yes Special Designs -Non-Traditional Methods Are any non-traditional methods (aquatic echosystems, wetland-type detention, natural stream replication, 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: Part 4 -Drainage Conceet and Design Parameters I 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 8-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 STORMWATER DESIGN GUIDELINES Effective February 2007 I Justification for Deviation (attach additional sheets if needed) Page 22 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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 applicatio~s made of the Rational Formula: What is the size and location of largest Design Drainage Area to which the Rational Formula has been applied? acres Location (or identifier): Part 4 -Drainage ConceRt and Design Parameters I Continued (Page 4.15) Design Parameters (continued) Hydrology (continued) In 7king determinations for time of concentration, was segment analysis used? No Yes In approximately what percent of Design Drainage Areas? % As to intensity-duration-frequency and rain depth criteria for dete~ing runoff flows, were any criteria other than those provided in these Guidelines used? __ No __ Yes If "yes" identify type of data, source(s), and where applied: STORMWATER DESIGN GUIDELINES Effective February 2007 Page 23 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY 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 Open channels Swale/buried conduit combination in lieu of channel Swales Roadside ditches and culverts serving them Detention facilities: spillway crest and its outfall 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) Lowest (feet per second) Streets and Stonn Drain Systems Provide the summary information outlined below: Roughness coefficients used: For street gutters: For conduit type(s) Coefficients: Part 4 -Drainage Conce~t and Design Parameters I 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 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? --Yes --No Explain any "no" answers: STORMWATER DESIGN GUIDELINES Effective February 2007 Page 24 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised Februarv 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Are hydraulic grade lines calculated and 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: Open Channels If a HEC analysis is utilized, does it follow Sec Vl.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 Part 4 -Drainage Conceet and Design Parameters j 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 f/vlx2.o-CAD MAJ ~oetv1.. Part 5 -Plans and Seecifications STORMWATER DESIGN GUIDELINES Effective February 2007 Page 25 of26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008 SECTION IX APPENDIX D -TECHNICAL DESIGN SUMMARY Requirements for submittal of construction drawings and specifications do not differ due to use of a Technical Design Summary Report. See Section· Ill, 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 Desi n Summa Draina e Re ort b si nin and sealin below. UThis report (plan) for the drainage design of the development named in Part 8 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 or fall under applicable general permits. n Licensed Professional Engineer State of Texas PE No .. __ 8_~_9_5_3 __ STORMWATER DESIGN GUIDELINES Effective February 2007 Page 26 of26 (Affix Seal) ~~ "11t.. ... _,,,,,,,,. ·~ ~ ~~~'.~-P!. r~* \'• ~ ••• ..A..,_ ··.•H ~.. ~ ·*" 11 •• : ••••••••••••••••• ~ APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2008