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I I I I I I I I I I I I I I I I I I I 4. Preparation of drawings showing the lOa-year flood hazard area in plan and profile, and the 10 year flood in profile. Natice - Flaod watep supface elevations and flaad plain baundaries ape aften pevised by poad and bpidge con- struction, fload plain develapment, flaad contpal im- ppavements, op natupal ppacesses. ~iap to' utilizatian of this pepapt fap planning ap design puppases, the usep is advised to' contact the Upban Dpainage & Flaad Cantpal Distpict op the Calapada Watep CanseT'Vation Baard to' determine if the informatian in this pepapt has been amended. Information Collected During the course of this study useful information was obtained from a number of sources. The Table below summarizes those contacted and the information ob- tained. Table I-I INFORMATION COLLECTED Agency UDFCD Information Provided Master Plan for the North Tributary of SJCD (South) - Basin 6200, interim up-date to CURP, guidelines on alter- natives. Jefferson County Engineering Department Preliminary drawings for proposed road crossing improvements, prelimi- nary and final plats, right-af-way information, and designation of im- portant transportation routes. Jefferson County Planning Department City of Littleton Projected development plans. Data on proposed park in So. Platte River fload plain. Soils information Soil Conservation Service Various developments and their engineers Layout and drainage planning infor- mation. 2 . II. BASIN DESCRIPTIONS Massey Draw and its North Tributary, andSJCD (South) - Basin 6200 and two of its tributaries are located in Jefferson County as shown on Plate I. The lower reach of SJCD (South) - Basin 6200 is located in Arapahoe County. The basins are located between the drainageways of Dutch Creek on the north and Deer Creek On the south. Flood History Information on the history of flooding within the study area is not abundant. Serious flooding has not occurred in recent years, probably because the basins have been largely undeveloped. The Jefferson County Engineering Department reported that the area experienced general flooding, as did most of the rest of the Denver Metropolitan area, on May 6, 1973. Half of the embankment of the South Carr Street crossing of Massey Draw was eroded away, and minor flood- ing on SJCD (South) - Basin 6200 caused inconvenience but no major damage. Massey Draw Massey Draw at South Wadsworth Boulevard, the dawnstream limit of study, drains an area of 7.84 square miles. The upper basin, that portion lying west of the Hogback Ridge, drains 5.14 square miles. The maximum elevation is 7955 feet and the average channel slope is 9.8%. Many individual tributaries come to- gether at a point west of the Hogback Ridge. In the lower basin the channel Slopes are less, averaging 1.4%. Gravel is being mined in the stretch between Sauth Garrison Street and South Carr Street. In the lower reach, Massey Draw passes through the Meadowbrook Heights subdivision. Most of the remainder of the basin is presently undeveloped. North Tributary of Massey Draw The Narth Tributary of Massey Draw drains an area of approximately 0.99 square miles. The upper reach extends into the Ken Caryl Ranch Plains subdivision to an elevation of approximately 5754 feet. Channel slopes average 1.9% over the entire length. The drainageway passes through portions of the Fairview Heights and the Meadowbrook Heights subdivisions. The downstream limit of the study is at South Wadsworth Boulevard. The North Tributary of Massey Draw joins Massey Draw at a point approximately 800 feet further downstream. ~ Leonard Rice Consulting Water Engineers, Inc.