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the inflow of water from the design storm event would result in overtopping of the dam. Free flow of <br />water over the dam could result in failure of the dam and sudden release of water from the reservoir. <br />Such an event would have the potential to cause loss of life and structure. <br />A/ternative No. 2- En/arqe the Spi//way with a Concrete Cont~o/ Structure <br />and Earthen Channe/s Upstream and Downstream from the Spi//way Crest <br />The second alternative explored was to modify the existing spillway by expanding it. The current spillway <br />crest, which is 350 feet wide, would be widened to 585.7 feet. The crest elevation of the existing and <br />widened section would be set at elevation 4,802.95, which is 1.5 feet below the existing spillway <br />elevation. Areas upstream and downstream of the spillway crest would be graded to provide an efficient <br />flow path from the reservoir through the spillway crest and on downstream of the dam. Appropriate <br />hydraulic cutoff walls would be added downstream from the spillway to prevent erosion during the <br />design storm event from undermining the facility, however the majority of the channel into and from the <br />spillway crest would be earthen material. Given the design storm event, localized erosion is anticipated <br />in the channel immediately upstream of the spillway and along the downstream channel. Were the event <br />to occur, maintenance of these channels by FRICO is expected to be required. Since the design event is <br />75% of the Probable Maximum Precipitation (PMP), the likelihood of the event ever occurring is <br />miniscule, therefore FRICO believes the potential maintenance requirements are acceptable. <br />This alternative would meet FRICO's objective of improving the spillway to safely pass the design storm <br />event as dictated by the SEO. Complying with the SEO's spillway requirement will allow FRICO to <br />continue to operate Milton Dam to its full decreed amount without the concern of dam overtopping. <br />Our opinion for the probable cost for Alternative No. 2 project is $1,006,145.25 as shown on Table 4 <br />below. <br />20 <br />