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MP2019-0004 1ST SUBMITTAL Preliminary Hydrology Report 2019-10-22For Property Located In A Portion of Sections 27 & 28, Township 6 South, Range 7 East, SBM La Quinta, California THE WAVE AT CORAL MOUNTAIN Tentative Tract Map 37815 October 2019 Prepared for: CM Wave Development, L.L.C. 2440 Junction Place, Suite 200 Boulder, CO 80301 JN: 2553 ` PRELIMINARY HYDROLOGY REPORT For Property Located In A Portion of Sections 27 & 28, Township 6 South, Range 7 East, SBM La Quinta, California THE WAVE AT CORAL MOUNTAIN Tentative Tract Map 37815 October 2019 Prepared for: CM Wave Development, L.L.C. 2440 Junction Place, Suite 200 Boulder, CO 80301 JN: 2553 ` PRELIMINARY HYDROLOGY REPORT The Wave at Coral Mountain Preliminary Hydrology Report TABLE OF CONTENTS PROJECT DESCRIPTION & LOCATION ........................................................................... 1 EXISTING SITE CONDITIONS ........................................................................................ 1 Flood Rate Map ..................................................................................................................1 Existing Topography ...........................................................................................................1 PROPOSED FLOOD CONTROL REQUIREMENTS ............................................................ 1 HYDROLOGY ANALYSIS DESIGN CRITERIA .................................................................... 1 Hydrologic Soil Group .........................................................................................................1 Antecedent Moisture Condition ...........................................................................................2 Land Use Classifications and Runoff Index Numbers .............................................................2 Precipitation Frequency Estimates .......................................................................................2 Site Infiltration ...................................................................................................................2 Proposed Land Use Summaries ............................................................................................3 SUMMARY of SYNTHETIC UNIT (SHORTCUT METHOD) ANALYSES ................................ 3 Drainage Area ‘A’ ...............................................................................................................3 Drainage Area ‘B’ ...............................................................................................................3 Drainage Area ‘C’ ...............................................................................................................3 Drainage Area ‘D’ ...............................................................................................................3 Drainage Area ‘E’................................................................................................................3 Drainage Area ‘F’ ................................................................................................................3 Drainage Area ‘G’ ...............................................................................................................4 Drainage Area ‘H’ ...............................................................................................................4 Drainage Area ‘I’ ................................................................................................................4 PRELIMINARY WQMP ANALYSES ................................................................................ 4 RESULTS AND CONCLUSIONS ...................................................................................... 4 LIST OF APPENDICES A. RIVERSIDE COUNTY TLMA VICINITY MAP B. NFIP FLOOD INSURANCE RATE MAP C. USDA NCSS HYDROLOGIC SOILS MAP D. NOAA ATLAS 14 & RCFCD REFERENCE PLATES E. LAND USE WORKSHEETS F. RCFCD SYNTHETIC UNIT HYDROGRAPH WORKSHEETS G. RIVERSIDE COUNTY WHITEWATER RIVER REGION WQMP WORKSHEETS H. HYDROLOGY EXHIBITS The Wave at Coral Mountain Preliminary Hydrology Report 1 PROJECT DESCRIPTION & LOCATION The project is proposed to consist of residential structures, a multi -story hotel complex, a wave lagoon and various outdoor amenities. The project site comprises approximately 377 acres with an additional 75 acres of offsite tributary area. The subject property is located on the southwest corner of Avenue 58 and Madison Street in the City of La Quinta and is situated in a portion of Sections 27 & 28, Township 6 South, Range 7 East, SBM. Existing dikes 2 & 4 along with the Coral Mountains border the prop erty to the west and south. A vicinity map obtained from the Riverside TLMA website is included as Appendix A. EXISTING SITE CONDITIONS Flood Rate Map The proposed area is covered by FIRM Panel Number 06065C 2900G, effective date of August 28, 2008, which indicates the subject property lies within Zone X (Shaded), defined as “Areas of 0.2% annual chance flood; areas of 1% annual chance flood with average depths of less than 1 foot or with drainage areas less than 1 square mile; and areas protected by levees from 1% annual chance flood. Insurance purchase is not required in these areas.” Refer to the attached NFIP Flood Insurance Rate Map in Appendix B. Existing Topography The property is generally vacant and undeveloped with CVWD irrigation mains, n umerous dirt road and hiking trails. Various desert vegetation is found throughout the site. The site is bounded to the east by Madison Street, to the north by 58th Avenue, existing levees and the Coral Mountains to the west and south, and 60th Avenue to the south. No groundwater was encountered in any of the exploratory borings to a depth of 51 feet. Site drainage appears to be controlled via sheet flow and surface infiltration generally from west to east. PROPOSED FLOOD CONTROL REQUIREMENTS The purpose of this report is to provide preliminary basin analyses for the subject property. The drainage requirements for this project fall under the jurisdiction of the City of La Quinta. Storm flows are conveyed through the site via street flow to localized low points. Existing improvements along Madison Street have in essence created a situation where there is no emergency out-flow for storm flows exceeding the 100-year storm event. Conversations are on-going with the owners of Andalusia (to the east of the subject property) to allow for an emergency overflow route to be constructed through the development. That being said, the existing retention basins at the low points on Madison Street will need to be preserved. HYDROLOGY ANALYSIS DESIGN CRITERIA Storm runoff volumes for the 100-year event were obtained utilizing the Synthetic Unit Hydrograph as described in the RCFC&WCD Hydrology Manual. The hydrologic data used for the calculations are as follows: Hydrologic Soil Group The existing soil is categorized primarily as hydrologic soil groups “A” and “B” for the majority of the subject property with soil group “D” being assigned to the Coral Mountain rock out-cropping as shown per the attached National Cooperative Soil Survey exhibits in Appendix C. For the purposes of this report, Soil Group B’ was assigned to the analyses with the exception of the rock out-cropping. Soil Group ‘B’ is defined by RCFCD as – “soils having moderate infiltration rates when thoroughly wetted and consisting chiefly of moderately deep to deep, moderately well to well drained soils with moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission”. The Wave at Coral Mountain Preliminary Hydrology Report 2 Soil Group ‘D’ is defined by RCFCD as – “soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high- water table, soils that have a claypan or clay layer at or near the surface and soils that are shallow over n early impervious material”. Antecedent Moisture Condition AMC II – Moderate runoff potential, an intermediate condition. Per RCFC & WCD Hydrology Manual (Dated: April 1978): “For the purposes of design hydrology using District methods, AMC II should normally be assumed for both the 10 year and 100 year frequency storm”. Land Use Classifications and Runoff Index Numbers Runoff Index Numbers were obtained from RCFCD Plates E6.1, E6.2 and E6.3 are summarized below: Commercial or Residential Landscaping (Soil Group B) 56 Rock Out-cropping (Soil Group D) 93 Existing Open Brush – Poor 76 Percent of Impervious Cover (RCFCD Plate E-6.3): Rock Out-cropping 5% Existing Open Brush – Poor Condition 5% Impervious Areas (Buildings, Pavement, Hardscape) 100% Water Features 100% Commercial Areas 90% SFR – Low Density 30% SFR – Medium Density 40% SFR – High Density 50% Open Space (Landscaping & Retention Basins) 10% Low Loss Rates: 85% Precipitation Frequency Estimates Precipitation depths were obtained from NOAA Atlas 14: 2 Year - 1 Hour Precipitation: 0.358 inches 10 Year – 1 Hour Precipitation: 0.711 inches 10 Year –3 Hour Precipitation: 1.06 inches 10 Year – 6 Hour Precipitation: 1.36 inches 10 Year – 24 Hour Precipitation: 2.23 inches 100 Year – 1 Hour Precipitation: 1.44 inches 100 Year – 3 Hour Precipitation: 2.14 inches 100 Year - 6 Hour Precipitation 2.76 inches 100 Year – 24 Hour Precipitation 4.41 inches Slope of Intensity Duration Curve: 0.52 See Appendix D for the NOAA Atlas 14 Point Precipitation Frequency Estimates and respective RCFCD Plates. Site Infiltration No percolation tests have been performed at the current time, therefore, for the purposes of this report a design percolation rate of 1 in/hr was used in the basin sizing calculations. The Wave at Coral Mountain Preliminary Hydrology Report 3 Proposed Land Use Summaries Land uses for each of the drainage areas were analyzed based on the pr eliminary site plan. In addition, a reconciliation was performed to verify the hydrologic boundary corresponds to the existing property boundary accounting for any differences. Land use worksheets are included in Appendix E. SUMMARY of SYNTHETIC UNIT (SHORTCUT METHOD) ANALYSES The proposed retention basins for the associated drainage areas were sized to retain the 100-year controlling storm event flood volumes and were analyzed utilizing the RCFCD Synthetic Unit (Shortcut Method). Per the manual, for areas of less than 100 – 200 acres, and lag times less than 7 – 8 minutes, the shortcut method is applicable. This method assumes that in a small watershed, response time to effective rainfall is very short. Therefore, runoff rates for a given period of time can be assumed t o be directly proportional to effective rain. This method yields only approximate results (on the conservative side) and should be used only for watersheds meeting the criteria noted above. It should be noted that the peak flow for the 1-hour storm is not necessarily representative for peak flow. Per RCFCD, peak discharges from the 3-hour storm should normally compare well with rational peaks. The synthetic unit worksheets are included in Appendix F and are summarized on sheets 1 and 2 of the hydrology exhibits in Appendix H. Drainage Area ‘A’ This area is located on the westerly portion of the project and consists primarily of Dike Number 2, the Coral Mountains, a portion of Dike Number 4, the south-westerly portion of Planning Area IX and Planning Area X. Storm runoff (approximately 18.4 acre-feet) from this drainage sub-area is directed to the wave lagoon which provides over 73 acre-feet of retention. Shallow basins are proposed to retain 10-year storm flows from drainage areas ‘A1’ & ‘A3’. During the final design process, once a more detailed land plan is provided, first flush storm flows from drainage area ‘A2’ will be captured prior to being discharged into the lagoon. Drainage Area ‘B’ Storm runoff of 4.2 acre-feet from this drainage area will be retained within the proposed lake. Drainage Area ‘C’ Storm runoff (roughly 1 acre-foot) for this drainage area will be conveyed to and retained in a temporary retention basin located in Drainage Area ‘F’. Drainage Area ‘D’ Storm runoff of approximately 3.1 acre-feet for this drainage area will be conveyed to and retained in the proposed lake located within the “Farm”. Drainage Area ‘E’ Storm runoff of approximately 5.7 acre-feet for this drainage area will be conveyed to and retained in a a large basin located in along the southerly portion of Planning Area VIII (Area 5). This basin will also provide a discharge location for the lagoon. Drainage Area ‘F’ This area is a future low-density residential development. Once developed it is anticipated approximately 4.0 acre-feet of retention will be required. The Wave at Coral Mountain Preliminary Hydrology Report 4 Drainage Area ‘G’ This area is a future low-density residential development. Once developed it is anticipated approximately 3.4 acre-feet of retention will be required. Drainage Area ‘H’ This area is a future commercial development. Once developed it is anticipated approximately 1.4 acre -feet of retention will be required. Drainage Area ‘I’ This area is a future low-density residential development. Once developed it is anticipated approximately 4.9 acre-feet of retention will be required. PRELIMINARY WQMP ANALYSES Preliminary design volume and flow for BMP measures were based on Worksheets 1 and 2 from the Riverside County – Whitewater River Region Water Quality Management Plan. Impervious area for the drainage sub - areas are derived from the preliminary land use worksheets. A summary of the BMP results are presented on sheet 1 of the Hydrology Exhibits in Appendix H with the worksheets being included as Appendix G.. RESULTS AND CONCLUSIONS As the above narrative and appendices confirm, the proposed retention basins are sufficiently sized to contain the flood volume from the controlling 100-year storm. During the final design process, a more detailed hydrologic report will be submitted to the City for review and approval. The Wave at Coral Mountain Preliminary Hydrology Report Appendix A Riverside County TLMA Vicinity Map IMPORTANT* Maps and data are to be used for reference purposes only. Map features are approximate, and are not necessarily accurate to surveying or engineering standards. The County of Riverside makes no warranty or guarantee as to the content (the source is often third party), accuracy, timeliness, or completeness of any of the data provided, and assumes no legal responsibility for the information contained on this map. Any use of this product with respect to accuracy and precision shall be the sole responsibility of the user. Riverside County GIS Legend THE WAVE Latitude: 33.6202 Longitude: -116.2562 Notes REPORT PRINTED ON...9/18/2019 9:08:13 AM MSA Job No. 2553 0 3,0091, 505 Feet Blueline Streams Survey City Areas World Street Map The Wave at Coral Mountain Preliminary Hydrology Report Appendix B NFIP Flood Insurance Rate Map DEFINITIONS OF FEMA FLOOD ZONE DESIGNATIONS Moderate to Low Risk Areas In communities that participate in the NFIP, flood insurance is available to all property owners and renters in these zones: ZONE DESCRIPTION X (Shaded) Areas of 0.2% annual chance flood; areas of 1% annual chance flood with average depths of less than 1 foot or with drainage areas less than 1 square mile; and areas protected by levees from 1% annual chance flood. Insurance purchase is not required in these zones. X Areas determined to be outside the 0.2% annual chance floodplain. High Risk Areas In communities that participate in the NFIP, mandatory flood insurance purchase requirements apply to all of these zones: ZONE DESCRIPTION A Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-year mortgage. Because detailed analyses are not performed for such areas; no depths or base flood elevations are shown within these zones. AE Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-year mortgage. In most instances, base flood elevations derived from detailed analyses are shown at selected intervals within these zones. AH Areas with a 1% annual chance of shallow flooding, usually in the form of a pond, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Base flood elevations derived from detailed analyses are shown at selected intervals within these zones. AO River or stream flood hazard areas, and areas with a 1% or greater chance of shallow flooding each year, usually in the form of sheet flow, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Average flood depths derived from detailed analyses are shown within these zones. For areas of alluvial fan flooding, velocities are also determined. AR Areas with a temporarily increased flood risk due to the building or restoration of a flood control system (such as a levee or a dam). Mandatory flood insurance purchase requirements will apply, but rates will not exceed the rates for unnumbered A zones if the structure is built or restored in compliance with Zone AR floodplain management regulations. A99 Areas with a 1% annual chance of flooding that will be protected by a Federal flood control system where construction has reached specified legal requirements. No depths or base flood elevations are shown within these zones. High Risk – Coastal Areas In communities that participate in the NFIP, mandatory flood insurance purchase requirements apply to all of these zones: ZONE DESCRIPTION V Coastal areas with a 1% or greater chance of flooding and an additional hazard associated with storm waves. These areas have a 26% chance of flooding over the life of a 30-year mortgage. No base flood elevations are shown within these zones. VE Coastal areas with a 1% or greater chance of flooding and an additional hazard associated with storm waves. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Base flood elevations derived from detailed analyses are shown at selected intervals within these zones. Undetermined Risk Areas ZONE DESCRIPTION D Areas with possible but undetermined flood hazards. No flood hazard analysis has been conducted. Flood insurance rates are commensurate with the uncertainty of the flood risk. The Wave at Coral Mountain Preliminary Hydrology Report Appendix C USDA NCSS Hydrologic Soils Map Hydrologic Soil Group—Riverside County, Coachella Valley Area, California THE WAVE) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/18/2019 Page 1 of4371910037194003719700372000037203003720600372090037212003721500371910037194003719700372000037203003720600372090037212003721500568100568400568700569000569300569600569900568100568400568700569000569300569600569900 33° 37' 56'' N 116° 16' 1'' W33° 37' 56'' N116° 14' 42'' W33° 36' 28'' N 116° 16' 1'' W33° 36' 28'' N 116° 14' 42'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 11N WGS84 0 500 1000 2000 3000 Feet 0 150 300 600 900 Meters Map Scale: 1:13, 200 if printed on A portrait (8.5" x MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Riverside County, Coachella Valley Area, California Survey Area Data: Version 10, Sep 13, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Dec 31, 2009—Oct 14, 2017 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Hydrologic Soil Group—Riverside County, Coachella Valley Area, California THE WAVE) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/18/2019 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI CdC Carsitas gravelly sand, 0 to 9 percent slopes A 50.9 6.9% CpA Coachella fine sand, 0 to 2 percent slopes A 50.2 6.8% CsA Coachella fine sandy loam, 0 to 2 percent slopes A 46.2 6.3% GaB Gilman loamy fine sand, 0 to 5 percent slopes B 23.4 3.2% GbA Gilman fine sandy loam, 0 to 2 percent slopes B 78.0 10.6% GbB Gilman fine sandy loam, 2 to 5 percent slopes B 10.7 1.5% GcA Gilman fine sandy loam, wet, 0 to 2 percent slopes B 89.1 12.1% GfA Gilman silt loam, wet, 0 to 2 percent slopes B 0.0 0.0% Ip Indio fine sandy loam B 40.7 5.5% Ir Indio fine sandy loam, wet B 70.9 9.6% Is Indio very fine sandy loam B 46.3 6.3% It Indio very fine sandy loam, wet B 127.7 17.3% MaB Myoma fine sand, 0 to 5 percent slopes A 55.0 7.4% RO Rock outcrop 49.8 6.7% Totals for Area of Interest 739.0 100.0% Hydrologic Soil Group—Riverside County, Coachella Valley Area, California THE WAVE Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/18/2019 Page 3 of 4 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Riverside County, Coachella Valley Area, California THE WAVE Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 9/18/2019 Page 4 of 4 The Wave at Coral Mountain Preliminary Hydrology Report Appendix D NOAA Atlas 14 RCFCD Reference Plates 9/18/2019 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=33.6202&lon=-116.2562&data=depth&units=english&series=pds NOAA Atlas 14, Volume 6, Version 2 Location name: La Quinta, California, USA* Latitude: 33.6202°, Longitude: -116.2562° Elevation: -31.22 ft** source: ESRI Maps source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maitaria, Deborah Martin, Sandra Pavlovic, Ishani Roy, Carl Trypaluk, Dale Unruh, Fenglin Yan, Michael Yekta, Tan Zhao, Geoffrey Bonnin, Daniel Brewer, Li-Chuan Chen, Tye Parzybok, John Yarchoan NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.066 0.056 0.080) 0.103 0.086 0.124) 0.156 0.130 0.189) 0.203 0.168 0.249) 0.277 0.221 0.350) 0.340 0.265 0.440) 0.412 0.313 0.547) 0.494 0.365 0.675) 0.622 0.440 0.887) 0.737 0.504 1.09) 10-min 0.095 0.080 0.115) 0.147 0.123 0.178) 0.223 0.186 0.271) 0.292 0.241 0.357) 0.397 0.316 0.502) 0.488 0.380 0.631) 0.590 0.449 0.783) 0.708 0.524 0.967) 0.891 0.631 1.27) 1.06 0.722 1.56) 15-min 0.115 0.096 0.139) 0.178 0.148 0.215) 0.270 0.225 0.327) 0.353 0.291 0.432) 0.480 0.382 0.607) 0.590 0.460 0.763) 0.714 0.543 0.947) 0.856 0.633 1.17) 1.08 0.763 1.54) 1.28 0.873 1.89) 30-min 0.165 0.138 0.200) 0.255 0.213 0.309) 0.387 0.322 0.470) 0.506 0.418 0.619) 0.688 0.549 0.872) 0.846 0.660 1.10) 1.02 0.780 1.36) 1.23 0.909 1.68) 1.55 1.10 2.21) 1.83 1.25 2.71) 60-min 0.232 0.194 0.280) 0.358 0.299 0.433) 0.543 0.452 0.660) 0.711 0.586 0.870) 0.966 0.771 1.22) 1.19 0.927 1.54) 1.44 1.10 1.91) 1.73 1.28 2.36) 2.17 1.54 3.10) 2.57 1.76 3.80) 2-hr 0.322 0.269 0.389) 0.473 0.395 0.572) 0.698 0.581 0.848) 0.906 0.747 1.11) 1.23 0.979 1.56) 1.51 1.18 1.95) 1.83 1.39 2.43) 2.20 1.63 3.01) 2.77 1.96 3.95) 3.28 2.24 4.85) 3-hr 0.388 0.324 0.468) 0.559 0.467 0.676) 0.818 0.681 0.993) 1.06 0.873 1.30) 1.43 1.14 1.82) 1.76 1.38 2.28) 2.14 1.63 2.84) 2.58 1.91 3.53) 3.26 2.31 4.65) 3.87 2.65 5.72) 6-hr 0.508 0.425 0.614) 0.726 0.606 0.879) 1.06 0.880 1.28) 1.36 1.13 1.67) 1.84 1.47 2.34) 2.27 1.77 2.94) 2.76 2.10 3.66) 3.32 2.46 4.54) 4.21 2.98 6.00) 5.00 3.42 7.38) 12-hr 0.610 0.509 0.737) 0.893 0.745 1.08) 1.32 1.10 1.60) 1.70 1.41 2.08) 2.30 1.83 2.91) 2.82 2.20 3.65) 3.42 2.60 4.53) 4.10 3.03 5.60) 5.14 3.64 7.33) 6.07 4.15 8.96) 24-hr 0.759 0.671 0.875) 1.15 1.01 1.33) 1.72 1.51 1.99) 2.23 1.95 2.60) 3.00 2.54 3.62) 3.67 3.05 4.51) 4.41 3.58 5.55) 5.25 4.15 6.79) 6.53 4.95 8.77) 7.63 5.60 10.6) 2-day 0.871 0.771 1.00) 1.34 1.18 1.54) 2.01 1.77 2.33) 2.61 2.28 3.05) 3.51 2.97 4.22) 4.27 3.54 5.24) 5.11 4.14 6.42) 6.04 4.77 7.81) 7.44 5.65 10.0) 8.63 6.34 12.0) 3-day 0.936 0.828 1.08) 1.44 1.28 1.67) 2.18 1.92 2.52) 2.83 2.47 3.30) 3.79 3.21 4.57) 4.61 3.83 5.66) 5.50 4.46 6.92) 6.50 5.13 8.40) 7.98 6.06 10.7) 9.24 6.79 12.9) 4-day 0.994 0.880 1.15) 1.54 1.36 1.77) 2.31 2.04 2.68) 3.00 2.63 3.50) 4.02 3.41 4.85) 4.88 4.06 6.00) 5.83 4.73 7.33) 6.88 5.43 8.89) 8.43 6.40 11.3) 9.76 7.16 13.6) 7-day 1.06 0.935 1.22) 1.63 1.44 1.88) 2.45 2.16 2.83) 3.17 2.77 3.70) 4.24 3.59 5.11) 5.14 4.26 6.31) 6.12 4.96 7.69) 7.20 5.69 9.30) 8.81 6.68 11.8) 10.2 7.46 14.1) 10-day 1.09 0.961 1.25) 1.67 1.48 1.93) 2.52 2.22 2.91) 3.26 2.85 3.80) 4.36 3.69 5.25) 5.28 4.38 6.48) 6.28 5.09 7.90) 7.38 5.83 9.54) 9.01 6.84 12.1) 10.4 7.62 14.4) 20-day 1.17 1.03 1.35) 1.82 1.61 2.10) 2.75 2.42 3.18) 3.57 3.12 4.17) 4.78 4.05 5.76) 5.79 4.81 7.12) 6.89 5.59 8.66) 8.09 6.39 10.4) 9.83 7.46 13.2) 11.3 8.29 15.7) 30-day 1.24 1.10 1.43) 1.96 1.73 2.26) 2.99 2.63 3.46) 3.90 3.41 4.55) 5.24 4.44 6.31) 6.35 5.27 7.81) 7.55 6.12 9.50) 8.86 6.99 11.4) 10.7 8.16 14.5) 12.3 9.04 17.1) 45-day 1.34 1.19 1.55) 2.15 1.90 2.49) 3.32 2.93 3.85) 4.35 3.81 5.08) 5.88 4.98 7.08) 7.14 5.93 8.77) 8.49 6.89 10.7) 9.96 7.87 12.9) 12.1 9.16 16.2) 13.8 10.1 19.2) 60-day 1.42 1.26 1.64) 2.31 2.04 2.67) 3.60 3.17 4.17) 4.73 4.14 5.52) 6.40 5.42 7.71) 7.78 6.46 9.56) 9.27 7.52 11.7) 10.9 8.58 14.0) 13.2 9.98 17.7) 15.0 11.0 20.9) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. PF graphical PROJECT NAME PROJECT NUMBER 2553 STORM EVENT 100 yr DATE: MINUTES RAINFALL RAINFALL INTENSITY DEPTH in/hr)(in) 5 4.94 0.41 10 3.54 0.59 15 2.86 0.71 30 2.04 1.02 60 1.44 1.44 120 0.92 1.83 CONSTANT FROM GRAPH 11.76 EXPONENT FROM GRAPH -0.52 MINUTES RAINFALL RAINFALL INTENSITY DEPTH in/hr)(in) 5 5.09 0.42 10 3.55 0.59 15 2.88 0.72 20 2.48 0.83 25 2.21 0.92 30 2.01 1.00 35 1.85 1.08 40 1.73 1.15 45 1.62 1.22 50 1.54 1.28 55 1.46 1.34 60 1.40 1.40 65 1.34 1.45 70 1.29 1.51 75 1.25 1.56 80 1.20 1.61 85 1.17 1.65 90 1.13 1.70 95 1.10 1.74 100 1.07 1.79 105 1.05 1.83 110 1.02 1.87 115 1.00 1.91 120 0.98 1.95 INTENSITY VALUES FROM GRAPH NOAA ATLAS 14 INTENSITY - DURATION WORKSHEET THE WAVE DATA FROM NOAA ATLAS 14 September 18, 2019 y = 11.76x-0.52 0.10 1.00 10.00 1 10 100 1000 The Wave at Coral Mountain Preliminary Hydrology Report Appendix E Preliminary Land Use Worksheets MSA JOB #2553 HYDROLOGIC SOIL GROUP B DRAINAGE AREA ROCK EXIST STREETS WATER COMMERCIAL PROPOSED PROPOSED PROPOSED PROPOSED TOTAL OUTCROPPING OPEN BRUSH WALKS FEATURE AREA RESIDENTIAL - LD RESIDENTIAL - MD RESIDENTIAL - HD OPEN SPACE RI=93 RI=76 RI=56 RI=56 RI=56 RI=56 RI=56 RI=56 RI=56 acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres) DA-A 35.660 35.233 1.890 18.699 5.845 0.000 0.000 7.488 57.356 162.171 DA-B 0.000 0.000 2.574 6.423 1.483 20.347 0.000 0.000 10.759 41.586 DA-C 0.000 0.000 1.454 0.000 0.000 0.000 4.092 2.159 2.486 10.191 DA-D 0.000 0.000 2.408 2.323 4.712 0.000 0.000 8.129 11.404 28.976 DA-E 0.000 0.000 1.749 0.000 0.000 49.206 0.000 4.271 7.677 62.903 SUBTOTAL 35.660 35.233 10.075 27.445 12.040 69.553 4.092 22.047 89.682 305.827 FUTURE BNDY - F 0.000 0.000 0.249 0.000 0.000 42.760 0.000 0.000 1.802 44.811 FUTURE BNDY - G 0.000 0.000 0.535 0.000 0.000 34.432 0.000 0.000 3.023 37.990 FUTURE BNDY - H 0.000 0.000 0.090 0.000 7.768 0.000 0.000 0.000 0.415 8.273 FUTURE BNDY - I 0.000 0.000 0.777 0.000 0.000 48.790 0.000 0.000 5.087 54.654 TOTAL SITE 35.660 35.233 11.726 27.445 19.808 195.535 4.092 22.047 100.009 451.555 AREA RECONCILIATION MEASURED AREAS: ROCK OUTCROPPING 35.660 EXIST OPEN BRUSH 35.233 STREETS/WALKS 11.726 WATER FEATURE 27.445 COMMERCIAL 19.808 LOTS - LOW DENSITY 195.535 LOTS - MED DENSITY 4.092 LOTS - HIGH DENSITY 22.047 OPEN SPACE 100.009 TOTAL HYDROLOGIC AREA 451.555 SURVEY BOUNDARY 377.206 ADD:74.991 SUBTRACT:0.642 TOTAL AREA:451.555 TTM 37815 - C.M. WAVE DEVELOPMENT October 21, 2019 PROPOSED LAND USE PROPOSED LAND USE AREAS - SYNTHETIC UNIT MSA JOB #2553 HYDROLOGIC SOIL GROUP B DRAINAGE AREA ROCK EXIST STREETS WATER COMMERCIAL PROPOSED PROPOSED PROPOSED PROPOSED TOTAL OUTCROPPING OPEN BRUSH WALKS FEATURE AREA RESIDENTIAL - LD RESIDENTIAL - MD RESIDENTIAL - HD OPEN SPACE RI=93 RI=76 RI=56 RI=56 RI=56 RI=56 RI=56 RI=56 RI=56 acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres) DA-A1 34.392 30.354 0.000 0.000 0.000 0.000 0.000 0.000 23.665 88.411 DA-A2 0.000 0.000 1.890 0.000 5.845 0.000 0.000 7.488 1.518 16.741 DA-A3 1.268 4.879 0.000 0.000 0.000 0.000 0.000 0.000 18.821 24.968 DA-A4 0.000 0.000 0.000 18.699 0.000 0.000 0.000 0.000 13.352 32.051 TOTAL - DA-A 35.660 35.233 1.890 18.699 5.845 0.000 0.000 7.488 57.356 162.171 TTM 37815 - C.M. WAVE DEVELOPMENT PROPOSED LAND USE AREAS - SYNTHETIC UNIT October 21, 2019 PROPOSED LAND USE MSA JOB #2553 HYDROLOGIC SOIL GROUP A DRAINAGE AREA ROCK EXISTING STREETS WATER COMMERCIAL RESIDENTIAL RESIDENTIAL RESIDENTIAL OPEN TOTAL IMPERVIOUS OUT-CROPPING OPEN BRUCH WALKS FEATURES LOW DENSITY MEDIUM DENSITY HIGH DENSITY SPACE AREA Ai=5%Ai=5%Ai=100%Ai=100%Ai=90%Ai=30%Ai=40%Ai=50%Ai=10% acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres)(acres) DA-A 35.660 35.233 1.890 18.699 5.845 0.000 0.000 7.488 57.356 162.171 38.874 DA-B 0.000 0.000 2.574 6.423 1.483 20.347 0.000 0.000 10.759 41.586 17.512 DA-C 0.000 0.000 1.454 0.000 0.000 0.000 4.092 2.159 2.486 10.191 4.419 DA-D 0.000 0.000 2.408 2.323 4.712 0.000 0.000 8.129 11.404 28.976 14.177 DA-E 0.000 0.000 1.749 0.000 0.000 49.206 0.000 4.271 7.677 62.903 19.414 DA-F 0.000 0.000 0.249 0.000 0.000 42.760 0.000 0.000 1.802 44.811 13.257 DA-G 0.000 0.000 0.535 0.000 0.000 34.432 0.000 0.000 3.023 37.990 11.167 DA-H 0.000 0.000 0.090 0.000 7.768 0.000 0.000 0.000 0.415 8.273 7.123 DA-I 0.000 0.000 0.777 0.000 0.000 48.790 0.000 0.000 5.087 54.654 15.923 TOTAL SITE 35.660 35.233 11.726 27.445 19.808 195.535 4.092 22.047 100.009 451.555 141.865 TTM 37815 - C. M. WAVE DEVELOPMENT WQMP LAND USE - IMPERVIOUS AREAS October 21, 2019 LAND USE The Wave at Coral Mountain Preliminary Hydrology Report Appendix F RCFCD Synthetic Unit Hydrograph Worksheets DLS 2 AMC II AREA SOIL TRIBUTARY AREAS ACRES LOW LOSS RI INFILTRATION IMPERVIOUS DESIG GROUP CONDITION NUMBER RATE PERCENT 11 D EXISTING BARREN 35.660 X 93 0.09 0.05 12 B EXISTING OPEN BRUSH - POOR 35.233 X 76 0.29 0.05 2 B PAVING/HARDSCAPE 1.890 D 56 0.51 1.00 3 B WATER FEATURE 18.699 D 56 0.51 1.00 1 B COMMERCIAL 5.845 D 56 0.51 0.90 6 B SF - HIGH DENSITY 7.488 D 56 0.51 0.50 9 B LANDSCAPING 57.356 D 56 0.51 0.10 1,180 ft 590 ft 960.0 ft ELEVATION OF CONCENTRATION POINT 456.0 ft 0.03 100 LOW LOSS RATE (Storm Events > 10 Years)85% POINT RAIN FROM NOAA ATLAS 14 1-HOUR 1.44 in 3-HOUR 2.14 in 6-HOUR 2.76 in 24-HOUR 4.41 in BASIN CHARACTERISTICS:ELEVATION AREA 451.0 ft 548,486 sf 456.0 ft 726,985 sf PERCOLATION RATE (in/hr)0.0 in/hr DRYWELL DATA NUMBER USED PERCOLATION RATE LOWEST FLOWLINE ELEVATION LOWEST PAD ELEVATION PROJECT NUMBER CONCENTRATION POINT DESIGNATION 2553 WAVE LAGOON AMC NUMBER RCFCD SYNTHETIC UNIT HYDROGRAPH - SHORTCUT METHOD DATA INPUT SHEET WORKSHEET PREPARED BY: PROJECT NAME DATE October 21, 2019 THE WAVE LENGTH OF WATERCOURSE (L) AREA DESIGNATION ELEVATION OF HEADWATER AVERAGE MANNINGS 'N' VALUE STORM FREQUENCY (YEAR) LENGTH TO POINT OPPOSITE CENTROID (Lca) Low Loss Conditions: X=Existing; D=Developed; BS=Retention DA-A Data Input Sheet Page 1 of 13 PROJECT: Job No.: BY:DATE:10/21/19 1] AMC II 2] FREQUENCY-YEARS 100 FROM NOAA ATLAS 14 3] STORM DURATION:Point Rain 1-HOUR 1.44 in 3-HOUR 2.14 in 6-HOUR 2.76 in 24-HOUR 4.41 in STORM DURATION 1-HOUR 3-HOUR 6-HOUR 24-HOUR RAINFALL VOLUME (cu-ft)847,704 1,259,782 1,624,765 2,596,092 SOIL LOSSES (cu-ft)156,666 463,367 838,222 1,796,275 EFFECTIVE RAIN (in)1.17 1.35 1.34 1.36 FLOOD VOLUME (cu-ft)691,038 796,415 786,543 799,818 acre-ft)15.86 18.28 18.06 18.36 REQUIRED STORAGE (cu-ft)691,038 796,415 786,543 799,818 acre-ft)15.86 18.28 18.06 18.36 FACTOR OF SAFETY 4.60 3.99 4.04 3.97 STORAGE PROVIDED (cu-ft) acre-ft) PEAK FLOW (cfs)n/a 300.82 259.77 60.61 MAXIMUM WSEL (ft)452.09 452.25 452.24 452.26 DEPTH (ft)1.09 1.25 1.24 1.26 DIFFERENCE (ft) DIFFERENCE (ft) ESTIMATED TIME TO DEWATER BASIN Based on Total Flood Volume & Average Percolation Rate (days) WAVE LAGOON DA-A THE WAVE 10] H-FEET 9] ELEVATION OF CONCENTRATION POINT 162.171 PHYSICAL DATA 1] CONCENTRATION POINT HYDROLOGY MANUAL BASIC DATA CALCULATION FORM 2553 DLS RCFC & WCD SYNTHETIC UNIT HYDROGRAPH METHOD 2] AREA DESIGNATION 3] AREA - ACRES 4] L-FEET 5] L-MILES 1180 0.223 13] L*LCA/S^0.5 47.49 11] S-FEET/MILE 6] La-FEET 7] La-MILES 8] ELEVATION OF HEADWATER 0.001 590.00 12] S^0.5 0.112 2255.2 960 456 504 0.03 17] 100% OF LAG-MINUTES 2.5 2.5 14] AVERAGE MANNINGS 'N' 15] LAG TIME-HOURS 0.04 16] LAG TIME-MINUTES 18] 200% OF LAG-MINUTES RAINFALL DATA 4.9 NOTE: PEAK FLOW FOR THE 1-HOUR STORM IS NOT REPRESENTATIVE. PER RCFCD PEAK DISCHARGES FROM THE 3-HOUR STORM SHOULD NORMALLY COMPARE WELL WITH RATIONAL PEAKS. LOWEST PAD ELEVATION LOWEST FLOWLINE ELEVATION STORM EVENT SUMMARY 3,178,217 72.96 Plate E-2.1 Page 2 of 13 PROJECT: Job No.: BY:DATE:10/21/19 MAX LOW LOW MIN SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AREA AVERAGE LOSS LOSS RATE AVERAGE GROUP NUMBER AREA PERCENT INFILTRATION WEIGHTED ADJUSTED CONDITION PER ADJUSTED INFILTRATION OF AREA RATE AVERAGE INFILTRATION RCFC/2322 INFILTRATION RATE IMPERVIOUS RATE RATE in/hr)(in/hr)(in/hr) Plate C-1][Plate E-6.1][Plate E-6.2][Plate E-6.3] D 93 0.09 5%0.09 35.660 0.220 0.0189 UNDEVELOPED 0.9000 0.1979 B 76 0.29 5%0.28 35.233 0.217 0.0602 UNDEVELOPED 0.9000 0.1955 B 56 0.51 100%0.05 1.890 0.012 0.0006 DEVELOPED 0.1000 0.0012 B 56 0.51 100%0.05 18.699 0.115 0.0059 DEVELOPED 0.1000 0.0115 B 56 0.51 90%0.10 5.845 0.036 0.0035 DEVELOPED 0.1800 0.0065 B 56 0.51 50%0.28 7.488 0.046 0.0130 DEVELOPED 0.5000 0.0231 B 56 0.51 10%0.46 57.356 0.354 0.1641 DEVELOPED 0.8200 0.2900 SUM 162.171 SUM 0.2661 0.7257 VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY) Fm=0.133064726 NOTE: Low loss rates established per RCFC/2322 (Dated: May-30-95) C=0.00246 For 10 Year Storms or Less Ft=C(24-(T/60))^1.55+Fm =0.00246 0.13 in/hr Undeveloped Condition: Low Loss = 90% CONSTANT LOSS RATE (3 & 6 HOUR STORMS)=0.2661 Developed Condition: Low Loss = 0.9 - (0.8 * %impervious) LOW LOSS RATE =0.8500 Basin Site: Low Loss = 10% Where:For 100 Year Storm - Low Loss should be between 80% & 90% T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,of the Rainfall Rate T=1 1/2 unit time for the second period, etc. AVERAGE ADJUSTED LOSS RATE RCFC & WCD HYDROLOGY MANUAL SYNTHETIC UNIT HYDROGRAPH METHOD BASIC DATA CALCULATION FORM THE WAVE DLS 2553 AMC II 24-(T/60))^1.55 + LAND USE EXISTING BARREN EXISTING OPEN BRUSH - POOR PAVING/HARDSCAPE WATER FEATURE COMMERCIAL SF - HIGH DENSITY LANDSCAPING Plate E-2.1 Page 3 of 13 PROJECT: Job No.:2553 BY:DLS DATE 10/21/19 DRAINAGE AREA-ACRES 162.17 Basin Percolation Rate 0.0 in/hr UNIT TIME-MINUTES 5 LAG TIME - MINUTES 2.45 Maxwell Drywells UNIT TIME-PERCENT OF LAG 204.0 Number 0 TOTAL ADJUSTED STORM RAIN-INCHES 1.44 Drywell Percolation Rate 0.00 cfs 0.00 cfm CONSTANT LOSS RATE-in/hr 0.27 LOW LOSS RATE - PERCENT 85.00% Unit Time Pattern Storm Effective Flood Volume Basin Basin Period Minutes Hours Percent Rain Rain Hydrograph In Volume Percolation Maximum Percolation WSEL in/hr Flow Area Percolation Out Plate E-5.9)Max Low in/hr cfs cu-ft cu-ft sf cu-ft cu-ft cu-ft ac-ft ft 1 5 0.08 3.6 0.62 0.27 0.53 0.36 58.21 17,462 17,462 549,467 0 0 17,462 0.40 451.03 2 10 0.17 4.2 0.73 0.27 0.62 0.46 75.16 22,548 40,010 550,733 0 0 40,010 0.92 451.06 3 15 0.25 4.4 0.76 0.27 0.65 0.49 80.81 24,243 64,253 552,095 0 0 64,253 1.48 451.10 4 20 0.33 4.6 0.79 0.27 0.68 0.53 86.46 25,939 90,192 553,551 0 0 90,192 2.07 451.14 5 25 0.42 5.0 0.86 0.27 0.73 0.60 97.77 29,330 119,522 555,199 0 0 119,522 2.74 451.19 6 30 0.50 5.6 0.97 0.27 0.82 0.70 114.72 34,416 153,938 557,132 0 0 153,938 3.53 451.24 7 35 0.58 6.4 1.11 0.27 0.94 0.84 137.33 41,198 195,135 559,445 0 0 195,135 4.48 451.31 8 40 0.67 8.1 1.40 0.27 1.19 1.13 185.36 55,608 250,744 562,569 0 0 250,744 5.76 451.39 9 45 0.75 13.1 2.26 0.27 1.92 2.00 326.65 97,994 348,738 568,072 0 0 348,738 8.01 451.55 10 50 0.83 34.5 5.96 0.27 5.07 5.70 931.34 279,402 628,140 583,764 0 0 628,140 14.42 451.99 11 55 0.92 6.7 1.16 0.27 0.98 0.89 145.80 43,741 671,880 586,221 0 0 671,880 15.42 452.06 12 60 1.00 3.8 0.66 0.27 0.56 0.39 63.86 19,157 691,038 587,297 0 0 691,038 15.86 452.09 TOTAL RAINFALL 1.44 in RAINFALL VOLUME 847,704 cu-ft SOIL LOSSES 156,666 cu-ft EFFECTIVE RAIN 1.17 in FLOOD VOLUME 15.86 acft FLOOD VOLUME 691,038 cu-ft REQUIRED STORAGE 15.86 REQUIRED STORAGE 691,038 cu-ft MAX WSEL 452.09 ft PEAK FLOW RATE 931.34 cfs TOTAL BASIN LOSSES 0 cu-ft AVERAGE PERCOLATION RATE 0.00 cf/min THEWAVERCFC & WCD HYDROLOGY MANUAL SYNTHETIC UNIT HYDROGRAPH METHOD SHORTCUT METHOD 1-HOUR STORM EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY UNIT HYDROGRAPH and EFFECTIVE RAIN CALCULATION FORM Total In Basin in/hr Time Loss Rate Basin Losses Plate E-2.2 1-Hour Storm Page 4 of 13 PROJECT: Job No.:2553 BY:DLS DATE DRAINAGE AREA-ACRES 162.17 Basin Percolation Rate 0.0 in/hr UNIT TIME-MINUTES 5 LAG TIME - MINUTES 2.45 Maxwell Drywells UNIT TIME-PERCENT OF LAG 204.0 Number 0 TOTAL ADJUSTED STORM RAIN (in)2.14 Drywell Percolation Rate 0.00 cfs 0.00 cfm CONSTANT LOSS RATE (in/hr)0.27 LOW LOSS RATE - PERCENT 85.00% Unit Time Pattern Storm Effective Flood Volume Basin Basin Period Minutes Hours Percent Rain Rain Hydrograph In Volume Percolation Maximum Percolation WSEL in/hr Flow Area Percolation Out Plate E-5.9)Max Low in/hr cfs cu-ft cu-ft sf cu-ft cu-ft cu-ft ac-ft ft 1 5 0.08 1.3 0.33 0.27 0.28 0.07 11.07 3,322 3,322 548,673 0 0 3,322 0.08 451.01 2 10 0.17 1.3 0.33 0.27 0.28 0.07 11.07 3,322 6,643 548,859 0 0 6,643 0.15 451.01 3 15 0.25 1.1 0.28 0.27 0.24 0.02 2.67 802 7,445 548,904 0 0 7,445 0.17 451.01 4 20 0.33 1.5 0.39 0.27 0.33 0.12 19.47 5,841 13,287 549,232 0 0 13,287 0.31 451.02 5 25 0.42 1.5 0.39 0.27 0.33 0.12 19.47 5,841 19,128 549,560 0 0 19,128 0.44 451.03 6 30 0.50 1.8 0.46 0.27 0.39 0.20 32.07 9,621 28,748 550,101 0 0 28,748 0.66 451.05 7 35 0.58 1.5 0.39 0.27 0.33 0.12 19.47 5,841 34,590 550,429 0 0 34,590 0.79 451.05 8 40 0.67 1.8 0.46 0.27 0.39 0.20 32.07 9,621 44,210 550,969 0 0 44,210 1.01 451.07 9 45 0.75 1.8 0.46 0.27 0.39 0.20 32.07 9,621 53,831 551,509 0 0 53,831 1.24 451.08 10 50 0.83 1.5 0.39 0.27 0.33 0.12 19.47 5,841 59,672 551,837 0 0 59,672 1.37 451.09 11 55 0.92 1.6 0.41 0.27 0.35 0.14 23.67 7,101 66,773 552,236 0 0 66,773 1.53 451.11 12 60 1.00 1.8 0.46 0.27 0.39 0.20 32.07 9,621 76,394 552,777 0 0 76,394 1.75 451.12 13 65 1.08 2.2 0.56 0.27 0.48 0.30 48.87 14,660 91,053 553,600 0 0 91,053 2.09 451.14 14 70 1.17 2.2 0.56 0.27 0.48 0.30 48.87 14,660 105,713 554,423 0 0 105,713 2.43 451.17 15 75 1.25 2.2 0.56 0.27 0.48 0.30 48.87 14,660 120,373 555,247 0 0 120,373 2.76 451.19 16 80 1.33 2.0 0.51 0.27 0.44 0.25 40.47 12,140 132,513 555,928 0 0 132,513 3.04 451.21 17 85 1.42 2.6 0.67 0.27 0.57 0.40 65.66 19,699 152,212 557,035 0 0 152,212 3.49 451.24 18 90 1.50 2.7 0.69 0.27 0.59 0.43 69.86 20,959 173,170 558,212 0 0 173,170 3.98 451.27 19 95 1.58 2.4 0.62 0.27 0.52 0.35 57.26 17,179 190,350 559,177 0 0 190,350 4.37 451.30 20 100 1.67 2.7 0.69 0.27 0.59 0.43 69.86 20,959 211,308 560,354 0 0 211,308 4.85 451.33 21 105 1.75 3.3 0.85 0.27 0.72 0.58 95.06 28,517 239,826 561,955 0 0 239,826 5.51 451.38 22 110 1.83 3.1 0.80 0.27 0.68 0.53 86.66 25,998 265,823 563,416 0 0 265,823 6.10 451.42 23 115 1.92 2.9 0.74 0.27 0.63 0.48 78.26 23,478 289,302 564,734 0 0 289,302 6.64 451.46 24 120 2.00 3.0 0.77 0.27 0.65 0.50 82.46 24,738 314,039 566,123 0 0 314,039 7.21 451.49 25 125 2.08 3.1 0.80 0.27 0.68 0.53 86.66 25,998 340,037 567,584 0 0 340,037 7.81 451.53 Total In Basin in/hr MANUAL 3-HOUR STORM UNIT HYDROGRAPH and EFFECTIVE RAIN CALCULATION FORM Time Loss Rate Basin Losses RCFC & WCD SYNTHETIC UNIT HYDROGRAPH METHOD THE WAVE HYDROLOGY SHORTCUT METHOD Plate E-2.2 3-Hour Storm Page 5 of 13