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<br />I <br /> <br />a flatter slope than the usual 2 horizontal to 1 vertical to allow for low drops or <br />site conditions. <br /> <br />I <br /> <br />I I <br /> <br />Design Guidelines and Criteria for Channels and Hydraulic Structures on Sandy Soils <br />(ref. 50) notes that these drops can be adapted to downstream bed degradation by <br />adding more baffles on a slope extension. The USBR states that design flow limilts <br />have been exceeded at several locations with no significant problems. <br /> <br />I <br /> <br />Downstream of the baffled chute, the USBR recommends a rock filled area that will <br /> <br /> <br />naturally rearrange to establish a stable bed condition and allow further stilling <br /> <br /> <br />action. Grouted and concrete basins have also been used that allow good transitions <br /> <br /> <br />to the downstream trickle and main channels. The structure lends itself to a variety <br /> <br /> <br />of soils and foundation conditions. <br /> <br />I <br />I <br /> <br />I <br /> <br />The potential for debris flow must be reviewed. The Army Corps of Engineers <br />(COE) generally recommends this type of drop for ephemeral streams, with some <br />caution regarding heavy debris flow streams because the baffles can clog and fill <br />the interstices, resulting in overflow and direct impingement of the jet on the <br />downstream channel. Apparently, there have not been any serious problems in the <br />Denver area, but then again, presently there are not many of these structures in place. <br /> <br />I <br />I <br />I <br /> <br />All of the Denver cases perform satisfactorily. The following comments are relatively <br /> <br />I <br />I <br />I <br />I <br />I' <br /> <br />CASES <br /> <br /> <br />The Bureau has documented performance on numerous baffled apron drops (ref. 7). <br /> <br /> <br />Almost all of the commentary relates to relat ively minor problems, such as, the need <br /> <br /> <br />for erosion protection in adjacent channels and above the chute walls where spray <br /> <br /> <br />can occur, and debris problems. <br /> <br />minor criticisms. <br /> <br />Case I - Meadowood Tributary, Aurora <br />Figure II-I illustrates one of the drops in the Meadowood Drainageway, (a Tollgate <br />Creek Tributary). The projects are located west of and parallel to Buckley Road, <br />between Hampden and Yale. This project was based on an analysis which concluded <br /> <br />I <br /> <br />I i <br /> <br />JI-2 <br /> <br />I <br />I <br />