Laserfiche WebLink
<br />. Roadside Swales. This is probably the least expensive method of providing bypass capacity, <br />but insufficient space exists on either side of Griffith Street for sufficient open channel <br />conveyance. <br />. Buried Conduit. This is probably the most practical approach. Griffith and Park Streets are <br />presently unpaved which would permit relatively inexpensive conduit - installation. <br />Additionally, the conveyance structures would not be visible to residents or tourists and so <br />there would be no negative aesthetic impacts. <br /> <br />had positive experience with inflatable dams in the past. The total required length of barriers <br />would be approximately 3,200 feet and the height of barriers would be approximately 3 feet. <br /> <br />Pros and cons associated with this approach are summarized below along with conceptual level <br />cost estimates. <br /> <br />Pros <br /> <br />The concept of a buried conduit bypass is attractive because of its lack of visibility and the fact <br />that the need for channel modifications (and thus environmental impacts and permits) is reduced <br />or eliminated. It also has secondary benefits associated with the ability to collect groundwater <br />seepage which represents a chronic problem for homeowners in the area. The only downside to <br />this option is that it is relatively costly. <br /> <br />Pros and cons for a buried conduit bypass on South Clear Creek are summarized below along <br />with conceptual level cost estimates. <br /> <br />· Inexpensive capital cost compared to other alternatives <br />cost with inflatable dams'" $70,000 <br />cost with concrete barriers", $127,000 <br />· Minimal permanent changes to historic district <br />· Draws on volunteer spirit of community for implementation <br />· Barriers (inflatable dams or concrete barriers) could be shared with other communities <br />county-wide or state-wide to reduce cost to Town <br /> <br />Pros (Buried Conduit) <br /> <br />Cons <br /> <br />. Reduction in basement flooding. Lower water levels in the South Clear Creek channel and <br />elimination of street flooding will reduce groundwater levels <br />. Weep holes could be provided in conduit to collect problem seepage from mountains on east <br />side of town <br />. No negative aesthetic impacts <br />. No negative environmental impacts <br />. No environmental permitting required <br /> <br />. High maintenance costs and tourism impacts in flood years <br />. Restricts or eliminates street access to II lots <br />. Requires post-storm street cleanup <br />· Requires keeping crews trained in installation procedures <br />. Lower performance reliability than permanent structural solutions (rubber or fabric dams <br />would be especially vulnerable to vandalism) <br /> <br />5.3 PUBLIC INPUT <br /> <br />Cons (Buried Conduit) <br /> <br />. Utility relocation <br />. High cost to convey 100-year discharge in excess of lO-year channel capacity <br />25-Year Protection (42" CMP) = 5236,000 <br />- . 50- Year Protection (54" CMP) = 5307,000 <br />I 00- Year Protection (60" CMP) '" $346,000 <br /> <br />On September 3, 1998 a public workshop was held in Georgetown in order to present a <br />preliminary analysis of alternatives and to obtain input from Town citizens on three issues: <br /> <br />· areas of the Town which historically experience flooding from either Clear Creek or South <br />Clear Creek and are not shown on the effective FIRM <br />· , the desired level of flood protection (recurrence interval) <br />. preferred alternatives <br /> <br />5.2.6 Temporary Bypass (Improved Flood Fighting) <br /> <br />Based on the results of the meeting, several areas of Town were identified which have had <br />historical flooding problems but which are not shown as inundated on the effective FIRM. These <br />general areas have been denoted in Figures 4-1 - 4-3 . Regarding the question of protection level. <br />Town members decided that in spite of the higher cost, the Flood Hazard Mitigation Plan should <br />provide protection from the 100-year event. Finally, two of the alternative mitigation concepts. <br />floodproofing and upstream storage, were eliminated from consideration as impractical. <br />Floodproofing of structures was deemed too expensive relative to other alternatives for the Town <br />to pursue as an overall solution to flooding problems. Additionally, the cooperation and <br />coordination that would be required with each individual building owner made this approach <br /> <br />This concept is an expansion of the flood fighting approach used by the Town in the past. Flows <br />in excess of the capacity of South Clear Creek would be diverted down Griffith Street, through <br />the ball field and finally to the train station parking lot to be released into Clear Creek. In order to <br />prevent overflows at Rose and Taos Streets as occurred in 1995, more flow would have to be <br />diverted and bypassed at Griffith Street. Flows could be confined to the streets, park and parking <br />lot using temporary placement of concrete highway barriers ("Jersey rails"), inflatable rubber or <br />fabric dams, or other methods to supplement traditional sandbagging. Clear Creek County has <br /> <br />5-7 <br /> <br />5-8 <br />