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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br /> TABLE 4 <br /> Reservoi r Routings of IDF's for Spill way <br /> Alternative No. 2 <br /> Flow, cfs Spi 11 way Depths, ft Freeboard <br /> Inflow Outfl ow Service Emergency (ft) <br />1. 1 OO-yea r <br /> 6-hour 542 192 2.5 0 1.7 <br />2. 1 DO-yea r <br /> 18-hour 997 620 3.8 1.0 0.4 <br />3. 100-year <br /> l8-hour * 997 580 4.1 1.3 0.1 <br />4. Assumption B <br /> Thunderstorm 660 327 2.9 0.1 1.3 <br /> <br />* 50% of Service Spillway <br /> <br />C. Sl ide <br /> <br />In addition to the proposed construction of a service spillway <br />and a new emergency spi 11 way, the sl i de problem to the west of the <br />existing spi 11 way needs to be corrected. It is proposed that the <br />material excavated for construction of the new emergency spillway will <br />be used to backfill the existing spillway channel to the levels indi- <br />cated on Figures II and VIII. Before the area is backfilled, however, <br />a French drain is recommended for installation in order to drain the <br />sl ide area of groundwater present which would tend to lubricate the <br />slide. Installation of the French drain will help ensure the stabil- <br />ity of the slide. Figures II and VIII show the location and a typical <br />cross section of the French drain. <br /> <br />- VI-5 - <br />