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<br />miscellaneous work items to install the pipe, typically cost <br />an additional $10 to $20 per lineal foot. Additional costs <br />would be incurred for the diversion headwall or turnout box <br />and slide gate. No right-of-way costs weIfe considered in <br />this analysis because the city owns the ptoperty. Final <br />design studies incorporating more detailed survey data and <br />sediment information could dictate the USEl of smaller <br />diameter pipe, in 'which case project cost:s would be reduced <br />proportionately. <br /> <br />At the adjacent diversion site, open ;channel conveyance <br />is also an option. One drawback to this qption would be the <br />interruption of access along the road (although alternate <br />access does exist). A culvert crossing or small footbridge <br />could be built to provide continuous access on the \Vest side <br />at additional expense. <br /> <br />Screeninq andior Filtration - Water diverted from the <br />Uncompahgre River 'will require screening and/or filtration <br />to prevent undesirable fish from enterinsr the pond. Several <br />methods were investigated, including: <br /> <br />1. A Primary Sedimentation Pond <br />2. A Streamside Subsurface Collector <br />3. An Offstream Subsurface Collector <br />4. A Rotating Fish Barrier <br />5. A Radial Subsurface Collector <br /> <br />There are sev,eral advantages and disadvantages to each <br />method. <br /> <br />Method 1 - A primary sedimentation pond could be <br />created by constructing a small dike around the inlet. In <br />order to allow sufficient settling time, the pond would need <br />to be approximately 1 acre in surface area: and include a <br />screened outlet works. <br /> <br />Methods 2 & 3 .. The streamside and oLfstream subsurface <br />collectors would r,equire approximately 100'-200 lineal feet <br />of perforated pipe, respectively. Additionally, a <br />substantial quanti.ty of rock and/or gravel: would be needed <br />for either method. From an environmental perspective, the <br />offstream collector would be preferred to the streamside <br />collector by preventing disturbance and loss of vegetation <br />on the streambank. However, in order to confidently use an <br />offstream collector, tests of existing soil conditions and <br />ground water measurement would be needed to verify that an <br />adequate, usable supply exists. <br /> <br />Method 4 - The rotating fish barrier is made of <br />stainless steel SCJ~een and has a mechanical device v!hich <br />causes it to rotate so that it is self-cle~ning. If this <br />method is employed" an open channel diversion would be <br />needed between the river and pond. <br /> <br />16 <br />