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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 />-8- <br /> <br />level. The computer program determined velocities in the lake for the rising and receding limbs of <br />the inflow hydrograph. The results indicated that although low initial velocities occur early in the <br />operational cycle due to backwater effects from the deflating dam, pond velocities sufficient for <br />sediment flushing occur as the dam becomes fully deflated. The recommended initial setting for the <br />upstream probe is a water level equivalent to a I-year storm, or approximately 500 cfs_ However it <br />is anticipated that refinements will be made in probe settings during the initial years of operation. <br /> <br />The subsurface pump station also houses pumps that serve various water features, An intake located <br />at the conduit inlet structure supplies lake water to the pump station via a 24-inch ductile-iron <br />pipeline. Up to 5 cfs of lake water can be supplied to a fountain and rock cascade at the upstream end <br />of the lake to supplement creek flows and provide aeration and recirculation of the impounded water. <br />Chemical feed equipment in the pump station enables treatment of this flow to control algae growth <br />or encourage settling/clarification during low flow. A second pump supplies multiple fountains in the <br />main urban plaza area and a ''water curtain" feature at the upstream face of the downtown conduit <br />entrance. A third pump serves a curved and terraced "water wall" where water returns to the lake by <br />a series of small fountains, spouts, and troughs. <br /> <br />All reinforced concrete walls in the downtown project are faced with sandstone veneer. Formal plazas <br />located over the box culvert entrance and at the terraced wall feature exposed aggregate concrete <br />pavement sections framed by interlocking paver bands. Extensive landscaping is also a significant part <br />of the project. Construction costs for this final phase of the flood control improvements were $2,6 <br />million, <br /> <br />Table 1 summarizes the construction costs for all phases of the $8_6 million Little Dry Creek Flood <br />Control Improvements project. <br />