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HomeMy WebLinkAboutRS_Hydrology Study_170920_v1 Vuecrest Estates HYDROLOGY STUDY CITY OF RENTON FILE NOS. LUA 13-000642 & LUA15-000026 Prepared by: Ed McCarthy, P.E., P.S. 9957 171st Avenue SE Renton, WA 98059 Tel. (425) 271-5734 Prepared for: Harbour Homes 1300 Dexter Ave N Suite 550 Seattle, Washington 98109 January 26, 2016 i Vuecrest Estates Hydrology Study TABLE OF CONTENTS 1. Background Information ............................................................................................. 1-1 2. Characteristics of Channel and Basin ......................................................................... 2-1 3. Hydraulic Assessment ................................................................................................. 3-1 4. Recommendations and Limitations ............................................................................. 4-1 5. References ................................................................................................................... 5-1 LIST OF FIGURES Figure 1. Vicinity Map .................................................................................................... 1-2  Figure 2. Soils Map ......................................................................................................... 2-4  Figure 3. Basin Map ........................................................................................................ 2-5  Figure 4. Floodplain Map ............................................................................................... 3-2  LIST OF TABLES Table 1. Basin Areas and Cover Types ............................................................................ 2-3 APPENDICES Appendix A. Photographs of the Subject Site Appendix B. Hydrology Modeling Appendix B.1 Design Storm Calculations Appendix B.2 StormShed Inputs and Results Appendix B.3 WWHM2012 Inputs and Results Appendix C. HEC-RAS Modeling 1-1 Vuecrest Estates Hydrology Study 1. BACKGROUND INFORMATION The Vuecrest property is located at the southern terminus of Smithers Avenue South in Renton, Washington (Tax Parcels 3123059048 and 3223059097) (Figure 1). The subject property is located within a catchment of the Upper Springbrook Creek basin, within the Black River watershed. A Category III wetland and Class 4 stream are located on the project site, collecting water from a relatively small upstream catchment. This report was prepared in response to a City of Renton information request. Harbour Homes, LLC is in the process of developing plans for a residential development (City of Renton Project Nos. LUA 13-000642 & LUA15-000026). The City has asked for a study to evaluate the hydraulics of a proposed culvert on the subject site that spans the onsite channel. The purpose of this report is to document the methods and results of the study conducted at the city’s request. The hydrology study presented herein was conducted in accordance with criteria specified for a Major Floodplain/Floodway Study as outlined in the King County Surface Water Design Manual (King County Department of Natural Resources, 2009) and generally accepted procedures used in the region for hydrology and hydraulic assessments. The hydraulic evaluations presented in this report are intended to provide the following flood-related information for the project:  Assess the hydraulic capacity of the onsite channel and proposed culvert for both the 100-year and 500-year peak flow rates.  Delineate the 100-year floodplain of the onsite channel under proposed developed conditions.  Estimate flow quantities for the hydraulics of the proposed culvert to support the scour analysis being conducted by the project geotechnical engineer.  Assess impacts from the proposed project on the channel and the delineated floodplain. . 2-1 Vuecrest Estates Hydrology Study 2. CHARACTERISTICS OF CHANNEL AND BASIN 2.1 Description of Drainage Course in the Study Area A visual inspection of the contributing basin, onsite wetlands and channel was conducted on January 23, 2016. It was raining at the time of the site visit and had rained 0.90 inch in the preceding 24 hours and 3.00 inches in the preceding 7 days (King County Panther Creek Rain Gauge 03u). The channel on the site has been categorized as a Class 4 stream (Wetland Resources, Inc. May 10, 2013). The channel begins at the outlet of a Category III wetland located in the northeast corner of the project site (Wetland Resources, Inc. April 8, 2013). At the time of the site visit, water was ponded in the wetland but no surface flow was discharging from the wetland to the channel. Along its course on the site, the channel passes through a forested area with relatively dense undergrowth. Based on surveyed data for the site, the reach of the channel in the study area has a slope ranging from 1 to 13 percent. The slope of the channel is approximately 9 percent at the location of the proposed culvert and steepens significantly downstream from the culvert. The channel has a forest duff and mud substrate with no signs of erosion. Overbank vegetation along the channel in the study area is predominately scrub shrub cover types. Although not well- distinguished by armoring or erosion, the average wetted width in the channel ranged from 4 to 8 feet on the day of the site visit. Flat sections of channel and forest debris on the ground have the tendency to increase the wetted width of the channel and reduce the flow velocities relative to sections of the channel that are cleaner with steeper gradient. The channel appears to have spring-like characteristics as its basin namesake implies. A significant portion of the channel’s hydrology is likely fed by groundwater and interflow. Flow to the channel appears to be sourced by discharge from the upstream wetland, seepage from surrounding slopes and surface runoff from the basin. 2.2 Contributing Basins I delineated the basin draining to the channel study area using City of Renton aerial topography with 2-foot contour intervals. King County GIS watershed catchment boundaries were also used to help delineate the basins draining to the study area. The contributing basin is in the upper extent of the Upper Springbrook Creek basin (Figure 3). A topographic break on the east boundary of the site’s contributing basin separates the Panther Creek basin to the east. A field reconnaissance was conducted to verify basin boundaries, and in particular to check cross culverts and hydraulic structures at key locations in the basin. The delineated basin contributing to the channel was evaluated in GIS to measure its contributing areas. The contributing basin areas were broken down by land use, cover type and soil categories. 2-2 Vuecrest Estates Hydrology Study An area of 5.6 acres was calculated to drain to the onsite wetland and channel under proposed developed conditions (Figure 3). Cover types for the contributing basin areas were based on a combination of land use zoning and estimated areas that would likely be kept in forest in the future to protect the wetland and channel (Table 1). Future build-out conditions in the basin were used in calculating the cover types for developed areas. R-8 Residential zoning, with an impervious area of 75 percent, was assumed for future build out. Soils in the basin are mapped as the Alderwood Series and were modeled as Hydrologic Soil Group C soils (Figure 2) (SCS, 1973). 2.3 Basin Hydrology I selected the hydrology model StormShed to estimate the 100-year and 500-year peak flow rates from the 5.6-acre basin draining to the onsite channel. Using StormShed allowed calculation of basin flow rates with return periods of 100-years and 500-years. The ability to predict a 500-year flow rate is not available in the most recent version of KCRTS or WWHM2012, both of which are continuous hydrology models conventionally used in basin assessments. StormShed is an event-based model, but since steady-state peak rates formed the basis of the culvert hydraulic analysis, there was no need to run a continuous hydrologic model such as KCRTS or WWHM2012. However, for the sake of comparison, I predicted the 100-year 15-minute peak flow rate from the basin draining to the onsite channel using WWHM2012. To assess the magnitude of precipitation for the less frequent 500-year storm, I applied Washington State Department of Ecology’s hydrograph analysis procedure that is conventionally used to design and evaluate overflow structures for reservoirs. Ecology’s Dam Safety Office (DSO) utilizes design storm selection criteria that have an eight-step format (Washington State Department of Ecology, October 2009). Using this analysis approach, design storms range from a 500-year storm (Step 1) to what is defined as Probable Maximum Precipitation (Step 8). I conservatively assumed full build out conditions in the contributing basin. I also assumed that any stormwater facilities in the basin would be ineffective for the larger storms evaluated. The precipitation amount for both 100-year and 500-year storms were computed for a 24-hour design storm (Appendix B.1). The hydrologic model Stormshed was then used to generate inflow hydrographs to the onsite channel and to predict the peak flow rates for the design storms. Rainfall amounts for the 100-year and 500-year (Design Step 1) 24-hour storms were calculated to be 4.89 and 5.80 inches, respectively (Appendix B.1). Standard curve numbers were used in the runoff calculations. For instance, impervious areas were modeled using a curve number of 98. Landscape areas were modeled using a curve number of 86, to represent lawn on Hydrologic Soil Group C soils. Forested areas were modeled using a curve number of 70. The wetland in the northeast corner of the site was modeled as impervious area to represent its water surface input under ponded conditions. StormShed model inputs for the contributing basin are provided in Appendix B.2. For the 5.60-acre basin, under built-out conditions, the 100-year and 500-year peak flow rates to the channel were estimated to be 3.42 and 4.26 cubic feet per second. In comparison, the WWHM2012 100-year 15-minute peak flow 2-3 Vuecrest Estates Hydrology Study rate to the site, including groundwater contributions, was predicted to be 2.63 cubic feet per second (Appendix B.3). Table 1. Basin Areas and Cover Types Basin Till Forest (AC) Till Grass (AC) Wetland (AC) Impervious (AC) Total (AC) B-001 2.30 0.75 0.30 2.25 5.60 Total 2.30 0.75 0.30 2.25 5.60 Note: Areas include 3.00 acres of R-8 residential development assumed under full buildout of basin. Impervious area of 75 percent assumed. Wetland area was modeled as impervious. 3-1 Vuecrest Estates Hydrology Study 3. HYDRAULIC ASSESSMENT 3.1 Hydraulic Assessment Methods The hydraulic model HEC-RAS (Version 4.1.0) was used to evaluate the channel system and the proposed culvert in the study reach. Procedures for a Major Floodplain/Floodway Study outlined in the King County Surface Water Design Manual (King County Department of Natural Resources, 2009) were followed in conducting the hydraulic analysis. A detailed field survey of the surrounding topography and channel was conducted by D.R. Strong Consulting Engineers. All elevation data used in developing the HEC-RAS cross sections are referenced to NAVD 88 vertical datum. Photographs of various portions of the site and reaches of the channel were taken during a field reconnaissance to document the hydrologic condition of the site and the channel's condition and character (Appendix A). The photographs, along with observations of channel substrate and vegetative cover, were also used to estimate the roughness coefficients for each reach of the channel (French, 1985). Based on observations of channel substrate and vegetative cover, a roughness coefficient of 0.065 was used for the center portion of the channel, representative of a slightly meandering channel with in-channel debris. Likewise, a roughness coefficient of 0.065 was used for the forest and brush covered overbank areas, representative of floodplains with medium-dense brush in winter months. Roughness coefficients are identified in the modeled channel cross sections shown in Appendix C. 3.2 Hydraulic Assessment Results HEC-RAS was used to evaluate the hydraulic capacity of the channel and proposed culvert and also to estimate base flood elevations for mapping the 100-year floodplain of the study reach. The hydraulic performance of the channel and proposed culvert were simulated for both the 100- year and 500-year peak flow rates (Appendix C). The model simulations assumed steady state conditions. The proposed arch culvert, having a 29-foot span, is included in the hydraulic model. However, the culvert was predicted to have no effects on the channel hydraulics because flows are contained within the natural channel inside the culvert for up to the 500-year peak flow rate. Channel velocities were predicted to range from 0.97 to 2.59 feet per second along the study reach for the 100-year flow rate. Velocities were predicted to range from 1.01 to 2.77 feet per second along the study reach for the 500-year flow rate. The flow velocity within the section of channel passing through the arched culvert was predicted to be 1.41 feet per second for the 100- year flow rate and be 1.62 feet per second for the 500-year flow rate. HEC-RAS channel cross sections, channel profiles, and tabulated modeling results are presented in Appendix C. Using the HEC-RAS modeling results, the 100-year floodplain was mapped for the study reach under proposed developed site conditions (Figure 4). 4-1 Vuecrest Estates Hydrology Study 4. RECOMMENDATIONS AND LIMITATIONS 4.1 Recommendations We understand that a scour analysis of the proposed culvert for the predicted 500-year will be prepared by the project geotechnical engineer. This analysis will help confirm the selected footing depth for the culvert design. Should field conditions of the channel geometry vary from the field survey in the culvert location used in the hydraulic analysis, the footing should be backfilled with adequate cover to provide protection from scour. 4.2 Limitations This report was prepared for use by Harbour Homes, LLC. This report is not intended for use by others, except as authorized by Harbour Homes, LLC. Floodplain elevations presented in this report are based on surveyed data for the study area. These data reflect the condition of the channel and hydraulic structures at the time of the survey. Other data were collected and analyzed using published methods according to generally accepted practices. If the conditions upon which our analysis is based change in the future, we reserve the right to modify our conclusions or recommendations. Within the limitations of scope, schedule and budget, our services have been executed in accordance with the generally accepted practices in this area at the time this report was prepared. No warranty or other conditions express or implied, should be understood. 5-1 5. REFERENCES French, Richard, H., 1985. Open-Channel Hydraulics. McGraw-Hill Book Company. New York. King County Department of Development and Environmental Services, December 2003. DDES Bulletin 38 – Flood Insurance and FEMA. Seattle. King County Department of Natural Resources, 2009. King County Surface Water Design Manual. Seattle. U.S. Department of Agriculture, Soil Conservation Service, 1973. Soil Survey of King County Area, Washington. Washington State Department of Ecology, July 1992a. Dam Safety Guidelines – Part II – Project Planning and Approval of Dam Construction or Modification. Publication 92-55B. Washington State Department of Ecology, October 2009. Dam Safety Guidelines - Technical Note 3: Design Storm Construction, OFTR 92-55G, Olympia, Wash. Wetland Resources, Inc. May 10, 2013. Supplemental Stream Study for Vuecrest, Renton, WA. Wetland Resources, Inc. Project #12174. Everett, Wash Wetland Resources, Inc. April 8, 2013. Critical Area Study for Vuecrest, Renton, WA. Wetland Resources, Inc. Project #12174. Everett, Wash. Vuecrest Estates Hydrology Study Appendices Appendix A. Photographs of the Subject Site Appendix B. Hydrologic Modeling Appendix B.1 Design Storm Calculations Appendix B.2 StormShed Inputs and Results Appendix B.3 WWHM2012 Inputs and Results Appendix C. HEC-RAS Modeling Vuecrest Estates Hydrology Study Appendix A. Photographs of the Subject Site Appendix A: Photographs of the Subject Site ▼ Photo Number 1 ▼ Photo Number 2 Date of Photo: 1-23-16 Date of Photo: 1-23-16 Location: Forested area south of wetland in northeastern portion of site. Location: South portion of the wetland in northeastern portion of site. Description: Typical forested area on site representative of the buffer that will be preserved surrounding onsite wetlands. Description: Water was ponded in the northern wetland at the time of the site visit but not flowing to the channel by overland flow. Appendix A: Photographs of the Subject Site ▼ Photo Number 3 ▼ Photo Number 4 Date of Photo: 1-23-16 Date of Photo: 1-23-16 Location: Typical reach of onsite channel. Location: Upstream extent of surface water ponded in southern portion of site. Description: The channel substrate is forest litter. Flow velocities in the channel were observed to be low at an estimated rate of 20 to 30 gallons per minute. Description: Water flows to the channel from an area of surface ponding in the southeast portion of the site. Vuecrest Estates Hydrology Study Appendix B. Hydrologic Modeling Appendix B.1 Design Storm Calculations Appendix B.2 StormShed Inputs and Results Appendix B.3 WWHM2012 Inputs and Results Vuecrest Estates Hydrology Study Appendix B.1. Design Storm Calculations Figure B.1 Long-Duration Precipitation Magnitude Frequency Curve (PrecipLookup1-Long.xls)Vuecrest Estates Worksheet for Computation of Long Duration Precipitation Magnitude-Frequency Curve Reference 1/25/2016 page 1 of 2 Input Input Project data : Dam location: Renton, WA Watershed Lat/Long:47.6020 deg. N 122.6908 deg. W (> 3 decimal places) Watershed elevation:440 feet (Lat/Long and elev for centroid of watershed) Climatic Region: 32 (MGS Look-up Calculator) Mean Annual Precip: 50.3 inches (MGS Look-up Calculator) Duration of interest: 24 hours (Index for long duration storm) Design Step: 5 (Worksheet from Tech Note 2) Drainage area: 0.0625 sq.miles. (Compare to small watershed < 10 sq.miles) Input Key equationsPrecipitation estimates are calculated from gridded data set files by the MGS Look-up Calculator (the "Calculator" tab in this workbook) using the four-parameter Kappa probablility distribution. The specific equations are described in more detail in the following references : Schaefer MG, Barker BL, Taylor GH and Wallis JR, Regional Precipitation-Frequency Analysis and Spatial Mapping of Precipitation for 24-Hour and 2-Hour Durations in Western Washington, prepared for Washington State Department of Transportation, Report WA-RD 544.1, MGS Engineering Consultants, March 2002. Schaefer MG, Barker BL, Taylor GH and Wallis JR, Regional Precipitation-Frequency Analysis and Spatial Mapping of Precipitation for 24-Hour and 2-Hour Durations in Eastern Washington, prepared for Washington State Department of Transportation, MGS Engineering Consultants, January 2006. The calculations were extended to the Dam Safety storms by the update to Technical Note 3. The gridded data sets are provided by Ecology along with this spreadsheet and look-up calculator. Scaling precipitation, Psd = DF * Pgds Use design factor = 1 Input where:Pgds = estimated 24-hr precip for selected frequency, inches DF = design factor Psd = scaling precip for 24-hr index period, inches Total storm precip = (scaling precip for 24-hr index) x (multiplier from mass curve for 72-hr storm) multiplier for 72-hr storm = 1.4153 for Climatic Region 32 (from Multipliers worksheet)Hyetograph no. 16 This project : 500 yr 10 yr 25 yr 100 yr Step 1 Step 2 Step 3 Frequency / design step :3.58 4.11 4.89 5.80 6.19 6.83 Precip estimate, Pgds (in.) :3.58 4.11 4.89 5.80 6.19 6.83 Scaling precipitation, Psd (in.) :5.06 5.81 6.93 8.21 8.75 9.66 Total precip for design storm : Step 4 Step 5 Step 6 Step 7 Step 8 PMP Frequency / design step : 7.47 8.11 8.75 9.39 10.03 13.00 Precip estimate, Pgds (in.) :7.47 8.11 8.75 9.39 10.03 13.00 Scaling precipitation, Psd (in.) :10.57 11.48 12.39 13.29 14.20 18.40 Total precip for design storm : Vuecrest Estates Hydrology Study Appendix B.2. StormShed Inputs and Results StormShed Report Monday, January 25, 2016 Project: Vuecrest Stormshed Page 1 StormShed Model Input and Results Project Precips 24-Hour Design Strom Precipitation Amounts [100-yr] 4.89 in [500-Yr] 5.80 in Contributing Drainage Areas Drainage Area: B-001 Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 3.0500 ac 73.93 0.69 hrs Impervious 2.5500 ac 98.00 0.21 hrs Total 5.6000 ac Supporting Data: Pervious CN Data: Forest 70.00 2.3000 ac LS 86.00 0.7500 ac Impervious CN Data: Imperv - R-8 98.00 2.5500 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet Flow 100.00 ft 5.00% 0.8000 31.99 min Channel Channel 500.00 ft 3.00% 5.0000 9.62 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet Pavement 100.00 ft 1.00% 0.0110 1.97 min Shallow Shallow Pavement 150.00 ft 1.00% 27.0000 0.93 min Channel Channel Flow 500.00 ft 3.00% 5.0000 9.62 min B-001 Event Summary: Predicted Peak Runoff Rates BasinID Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac /Loss B-001 3.42 8.00 1.5661 5.60 SBUH/SCS TYPE1A 100-yr B-001 4.26 8.00 1.9473 5.60 SBUH/SCS TYPE1A 500-Yr Vuecrest Estates Hydrology Study Appendix B.3. WWHM2012 Inputs and Results WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Vuecrest Hydrology Site Name: Vuecrest Estates Site Address: City : Report Date: 1/25/2016 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2015/11/13 Version : 4.2.11 ___________________________________________________________________ MITIGATED LAND USE Name : CulvertBasin Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Mod 2.3 C, Lawn, Mod .75 Pervious Total 3.05 Impervious Land Use acre ROADS MOD 2.25 PARKING FLAT 0.3 Impervious Total 2.55 Basin Total 5.6 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:3.05 Total Impervious Area:2.55 ___________________________________________________________________ Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.200562 5 year 1.545283 10 year 1.78782 25 year 2.111231 50 year 2.364877 100 year 2.629757 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 3.432 1.633 1950 3.024 1.505 1951 2.050 1.017 1952 1.558 0.758 1953 1.780 0.883 1954 2.005 0.976 1955 2.309 1.110 1956 2.012 0.992 1957 2.480 1.205 1958 1.958 0.965 1959 2.004 1.000 1960 2.324 1.142 1961 2.098 1.026 1962 1.673 0.828 1963 2.203 1.067 1964 1.960 0.972 1965 2.523 1.209 1966 1.750 0.864 1967 3.178 1.508 1968 3.756 1.783 1969 2.287 1.083 1970 2.292 1.121 1971 2.775 1.335 1972 2.920 1.387 1973 1.612 0.808 1974 2.668 1.269 1975 2.520 1.235 1976 2.139 1.043 1977 2.041 0.970 1978 2.758 1.355 1979 3.353 1.659 1980 4.247 1.989 1981 2.349 1.146 1982 3.504 1.661 1983 2.658 1.309 1984 1.793 0.879 1985 2.268 1.089 1986 2.127 1.061 1987 2.981 1.480 1988 1.918 0.935 1989 3.002 1.473 1990 4.973 2.350 1991 4.039 1.903 1992 1.896 0.924 1993 2.101 1.016 1994 1.810 0.891 1995 2.114 1.036 1996 3.028 1.462 1997 2.364 1.162 1998 2.317 1.102 1999 5.204 2.417 2000 2.358 1.149 2001 2.640 1.299 2002 3.040 1.427 2003 3.167 1.507 2004 4.972 2.326 2005 1.985 0.981 2006 1.921 0.945 2007 4.734 2.200 2008 3.753 1.780 2009 3.167 1.569 _____________________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2016; All Rights Reserved. Vuecrest Estates Hydrology Study Appendix C. HEC-RAS Modeling Note: All elevation data are referenced to NAVD 88. 0100200300400500350355360365370375380Vuecrest Estates Plan: Proposed 1/25/2016 Main Channel Distance (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundSTA 0+62STA 1+13STA 1+54Proposed CulvertSTA 2+45STA 2+95STA 3+49STA 3+95STA 4+51STA 4+991 in Horiz. = 60 ft 1 in Vert. = 6 ft 020406080100375380385390Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 499 STA 4+99Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100375380385390Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 451 STA 4+51Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100375380385390Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 395 STA 3+95Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.0651 in Horiz. = 12 ft 1 in Vert. = 15 ft 020406080100375380385390Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 349 STA 3+49Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100370375380385Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 295 STA 2+95Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100370375380385Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 245 STA 2+45Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.0651 in Horiz. = 12 ft 1 in Vert. = 15 ft 020406080100370375380385Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 236 Culv Proposed CulvertStation (ft)Elevation (ft)LegendWS 100-yrWS 500-yrGroundBank Sta.065.065.065020406080100365370375380Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 236 Culv Proposed CulvertStation (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100365370375380Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 154 STA 1+54Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.0651 in Horiz. = 12 ft 1 in Vert. = 15 ft 020406080100365370375380Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 113 STA 1+13Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100360365370375Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 62 STA 0+62Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.065020406080100355360365370Vuecrest Estates Plan: Proposed 1/25/2016 River = Vuecrest Reach = Main RS = 0 SRA 0+00Station (ft)Elevation (ft)LegendWS 500-yrWS 100-yrGroundBank Sta.065.065.0651 in Horiz. = 12 ft 1 in Vert. = 15 ft HEC-RAS Plan: Proposed River: Vuecrest Reach: MainReach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft) Main 499 100-yr 3.42 375.27 375.78 375.60 375.80 0.009302 0.97 3.59 14.03 0.32Main 499 500-yr 4.26 375.27 375.82 375.63 375.84 0.009336 1.05 4.19 15.16 0.32Main 451 100-yr 3.42 374.21 374.61 374.61 374.72 0.108037 2.57 1.33 6.58 1.01Main 451 500-yr 4.26 374.21 374.65 374.65 374.76 0.101920 2.66 1.60 7.23 1.00Main 395 100-yr 3.42 372.63 373.16 372.90 373.17 0.003979 0.69 4.93 14.71 0.21Main 395 500-yr 4.26 372.63 373.21 372.93 373.22 0.004141 0.75 5.66 15.43 0.22Main 349 100-yr 3.42 372.13 372.54 372.54 372.64 0.108715 2.59 1.32 6.47 1.01Main 349 500-yr 4.26 372.13 372.58 372.58 372.69 0.102166 2.67 1.59 7.11 1.00Main 295 100-yr 3.42 369.00 369.77 369.53 369.80 0.014355 1.42 2.41 6.24 0.40Main 295 500-yr 4.26 369.00 369.83 369.59 369.87 0.014829 1.52 2.81 6.73 0.41Main 245 100-yr 3.42 367.96 368.16 368.16 368.23 0.113499 2.22 1.55 10.14 0.99Main 245 500-yr 4.26 367.96 368.18 368.18 368.27 0.110644 2.37 1.81 10.55 1.00Main 236 CulvertMain 154 100-yr 3.42 365.00 365.45 365.30 365.47 0.013106 0.97 3.51 15.46 0.36Main 154 500-yr 4.26 365.00 365.50 365.51 0.012408 1.01 4.23 16.96 0.36Main 113 100-yr 3.42 364.00 364.39 364.34 364.47 0.059918 2.28 1.50 5.71 0.78Main 113 500-yr 4.26 364.00 364.43 364.38 364.52 0.063351 2.46 1.73 6.07 0.81Main 62 100-yr 3.42 360.00 360.16 360.16 360.23 0.122875 2.21 1.55 10.65 1.02Main 62 500-yr 4.26 360.00 360.18 360.18 360.27 0.114641 2.34 1.82 10.92 1.01Main 0 100-yr 3.42 352.80 353.22 353.22 353.32 0.100066 2.55 1.34 6.34 0.98Main 0 500-yr 4.26 352.80 353.25 353.25 353.37 0.107889 2.77 1.54 6.79 1.03 HEC-RAS Plan: Proposed River: Vuecrest Reach: MainReach River Sta Profile E.G. US. W.S. US. E.G. IC E.G. OC Min El Weir Flow Q Culv Group Q Weir Delta WS Culv Vel US Culv Vel DS(ft) (ft) (ft) (ft) (ft) (cfs) (cfs) (ft) (ft/s) (ft/s)Main 236 Culvert #1 100-yr 368.13 368.16 368.13 368.13 380.01 3.42 2.70 1.41 1.55Main 236 Culvert #1 500-yr 368.15 368.18 368.15 368.15 380.01 4.26 2.68 1.62 1.68