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<br />I <br /> <br />I <br /> <br />I <br />I. <br /> <br /> <br />The following individuals participated in <br />information <br /> <br />meetings, providing valuable Insights and <br /> <br />1-1 <br /> <br />the project <br /> <br />1 <br /> <br />3 <br /> <br />Mapping and Surveys <br /> <br />The <br /> <br />1 <br /> <br />The major drainageway analysis was performed in accordance with the Jefferson County Storm <br />Drainage Design and Technical Criteria (Reference 3) and the Urban Storm Drainage Criteria Manua <br />(Reference 4). <br /> <br />6 <br /> <br />Acknowledgments <br /> <br />I <br /> <br />. <br /> <br />I <br /> <br />. <br /> <br />. <br />. <br /> <br />100-year <br /> <br />water <br /> <br />1 <br /> <br />5 <br /> <br />Analysis and Design Criteria <br /> <br />Technical Appendix for Letter of Map Revision, Muller <br />1990 <br /> <br />Engineering Company, me, <br /> <br />Revise July <br /> <br />11 <br /> <br />Design Report for North Tributary of Massey Draw Drainage Improvements, <br />Company, Inc., January 1986 <br /> <br />'I' <br /> <br />The purpose of the Massey Draw and SJCD (South) <br />Hazard Area Delineation (FHAD) is to: <br /> <br />Muller <br /> <br />Engineering <br /> <br />I <br /> <br />'I <br />I <br /> <br />Since the Original Plan was prepared, the Ken Caryl Ranch area west of the hogback (and C-470) has <br />been developed, the Natural Resources Conservation Service (NRCS), formerly Soil Conservation <br />Service, produced more detailed soils maps that indicated substantially lower infiltration rates west of <br />the hogback, and new hydrologic modeling methodologies have been adopted. The combination of <br />these factors resulted in significantly increased flow rates at the hogback, In 1982, the Massey Draw <br />hydrology was updated, which resulted in the 1 OO-year flows being increased from 23 percent to 211 <br />percent at various points along Massey Draw. In addition, Jefferson County, UDFCD, and private <br />developers have constructed drainage improvements in both watersheds. <br /> <br />Major <br /> <br />Drainageway Planning Update. Flood <br /> <br />The Meadows Sanctuary, J,F, Sato & Associates <br /> <br />Regional Detention Study for Massey Draw from Ken-Caryl Avenue to Kipling Parkway, JR <br />Engineering, lTD., Revised March 16, 1998 <br /> <br />Map Works prepared topographic mapping for the project under separate contract with UDFCD <br />maps were compiled and prepared at a scale of 1" = 1 00' with 2-foot contour intervals. The <br />topography was compiled from aerial photographs taken on September 2, 2003. The project mapping <br />is based on the NA VD 1988 vertical datum and the NAD 1983 horizontal datum. The maps were <br />submitted in an AutoCAD Version 2000 drawing format. Base maps for the hydrologic maps consist of <br /> <br />nc. <br /> <br />Revised September 8 <br /> <br />997 <br /> <br />"The Valley," Massey Draw North Village Tributary, Extension of 1 00- Year Flood Plain Study, Muller <br />Engineering Company, Inc" November 22. 1985 <br /> <br />/1 <br /> <br />I <br /> <br />The project study area consists of the Massey Draw and SJCD (South) watersheds and is presented in <br />Figure 1. Except for the North Tributary of SJCD (South), both watersheds were originally studied in <br />1979. The study results were presented in a report titled Flood Hazard Area Delineation, Massey <br />Draw & North Tributary, SJCD (South) 6200 & Tributaries (Original Plan, Reference 1), The North <br />Tributary of SJCD (South) was studied in 1976 and the results were presented in the major <br />drainageway planning study for SJCD (North)-Basin 6100 (Reference 2). The North Tributary of <br />SJCD (South) is included in the scope of the masterplan update, <br /> <br />'The Valley," Massey Draw North Village Tributary <br />Company, Inc" May 1984 <br /> <br />100-Year Flood Plain Study, MUlier Engineering <br /> <br />Revised Preliminary Stormwater Detention Study, "The Valley," Muller <br />September 1982 <br /> <br />Define the water surface profiles for the 1 0-, 50-, 100- and 500-year storm events. <br />Define two floodways, based on encroachment resulting in maximum increases of the energy <br />gradeline of 0.5 foot and 1.0 foot. <br />Prepare plan and profile drawings showing the 1 OO-year floodplain and 10- and <br />surface profiles. <br />Preparation of a FHAD report. <br /> <br />Engineering Company, Inc, <br /> <br />Design Report for the Channelization of Massey Draw Between Garrison Street and South Carr <br />Street, MSM Consultants, Inc" March 1981 <br /> <br />'I <br /> <br />, <br /> <br />'I <br />~I <br /> <br />1 <br /> <br />This report is part of a study co-sponsored by Urban Drainage and Flood Control District (UDFCD), <br />Jefferson County and the City of Littleton. The Agreement Regarding Major Drainageway Planning for <br />Massey Draw and SJCD (South) Drainageways Update (Agreement No, 03-08,06) was executed on <br />December 8, 2003. Addendum No, 1 subsequently amended the agreement to include a Flood <br />Hazard Area Delineation (FHAD) Study. Addendum No, 1 was executed on January 2, 2004. <br />Addendum No, 2, executed June 16, 2004, amended the agreement to include additional topographic <br />surveying. Addendum No, 3, executed July 21, 2004, amended the agreement to include additional <br />investigation and analyses related to the June 27,2004 flood on Massey Draw, <br /> <br />2 <br /> <br />Purpose and Scope <br /> <br />Final Drainage Report for Wingate South <br /> <br />In addition to <br />has occurred <br /> <br />Background Information <br /> <br />1 <br /> <br />USGS 7.5-minute quadrangle sheets and 30 meter digital elevation models obtained from the U,S <br />Geological Survey. Soil surveys were obtained from the Natural Resource Conservation Service, <br />land use information was obtained from the Jefferson County IT Development Department. An <br />inventory of drainage structures completed by JR Engineering in December 2003 contains information <br />on culverts in the watershed. <br /> <br />4 <br /> <br />Final Stormwater Detention Study, "The Valley," Muller <br />1984 <br /> <br />the Original Plan, the project sponsors provided studies related <br />in the study area. which included <br /> <br />MSM Consultants <br /> <br />Engineering Company <br /> <br />the development that <br /> <br />nc. <br /> <br />March <br /> <br />1981 <br /> <br />to <br /> <br />nc <br /> <br />Revised May 5 <br /> <br />1 <br /> <br />1 <br /> <br />Authorization <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />1. <br /> <br /> <br />Introduction <br /> <br />CIty 0/' Littleton <br /> <br /> <br />Flood Hazard Area Delineation <br />Massey Draw and SJCD (South) <br />December 2005 <br />