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6.2.2 Drainage Outlet Cleanout <br />It is recommended that the three outfall pipes of the sub -drain system be cleaned to remove <br />sediment and try to alleviate the remaining seepage around the outlet that is indicative of head <br />buildup in one or more of the pipes. The outlets were previously covered and still appear to be <br />partially clogged as discussed in Section 3.2. A water jetting or similar technology compatible <br />with the pipe materials is recommended. The cleanout should be conducted at least to the <br />nearest horizontal angle of the pipe collector system. The minimum portion (estimated at 400 ft) <br />of the collector pipe system recommended to be cleaned is depicted in Figure 21. A camera <br />inspection is recommended subsequent to cleanout. The camera inspection should be reviewed <br />by a qualified Professional Engineer and if the seepage is not mitigated or cleanout cannot be <br />conducted in the minimum section indicated in each pipe, additional measures such as the <br />addition of a protective filter blanket around the pipe outlets to prevent piping (internal erosion <br />of soils around the pipe) may be necessary. <br />COLLECTION <br />POND <br />.rr ' <br />r� <br />(From Drawing 14711 -105, As -Built of Pipe Underdrain System (SRK, 1991)) <br />Figure 21 Recommended Minimum Pipe Cleanout <br />Section <br />San Luis Project Miller Geotechnical Consultants <br />Tailing Dam Data Report 57 February 2014 <br />