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Reach 'l -- Station 135 +00 - 148f65+ (south and west end) <br />Recently in the last several years) large riprap was placed covering entire <br />face Smoothly shaped levee grading <br />Relatively low I00 -year water velocity against levee <br />Reach 2 - Station 128+60 - 135 +00 (south central) <br />Older moderate size riprap, with vegetation covering part of face <br />Somewhat irregularly shaped levee grading <br />M oderate 100 -gear water velocity against levee <br />Reach 3- Station 105-r00 - 128+60 (centr2land north end) <br />No riprap on face <br />Native grass and goods covering slope face <br />Irregularly shaped levee grading <br />Moderate to high I00 -year water velocity against levee <br />• A complete levee generally exists, tied in to high ground on each end; reclamation of <br />rained ground area on the inside of the levee was underway, including grading activity <br />on the inside and crest of the levee. <br />Wolman Courts were made to establish riprap gradation for riprap rock erosion <br />.Protection existing in reaches I and 2, 2nd rock available for use as riprap stockpiled <br />on -site. <br />• Laboratory testing of field samples was used to establish the gradation of subbase <br />material and bare earth levee s u rf2ces. <br />complete summary of levee erosion protection and related characteristics by reach versus <br />the adopted standards are shown on the attached `Fable 1. <br />ANALYSIS <br />The criteria which were utilized for levee erosion protection evaluation are fund in the <br />Deaver area urban Drainage and Flood control District's ") r inage Criteria 11 anual - <br />Volume I and Volume " uD &FCD 1 000). These criteria were established for flow in active <br />charnels versus flow in an overbank area as is the case with the Deepe Pit levee and are <br />generally more conservative than Federal Emergency Management criteria (FEMA 199 7; <br />FEMA 5/1986; and FEMA 1080), the Corps of Engineers criteria USAC E 078) and the <br />Mate of Colorado criteria C Dl l 1083). using this criteria and hydraulic characteristics at <br />representative cross sections in each reach, it eras first determined if erosion protection <br />better than simple compacted embankment was needed and, second, using rock nprap as <br />the slope armoring method, ghat the desired riprep characteristics need to be and third, if <br />the characteristics were not met, what needed to be done to correct the situation. <br />Reach I - Representative e Cross Section G&O 20330 <br />Reach 2 - representative Cross Section G&O 24030 <br />Reach 3 - Representative cross Section G&O 24270 <br />2 Ayres Associates <br />