Laserfiche WebLink
such has slowly raised the hydraulic grade of the <br />creek over time rendering the bridge functionally <br />obsolete from a hydraulic standpoint. The effects of <br />this sediment deposition can be seen in the creek <br />channel up to 200 feet above the bridge. The <br />elevation in the immediate vicinity of the bridge has <br />been maintained by annual dredging, but the creek <br />channel is essentially at the roadway elevation. <br />This hydraulic system (Wilson/Naneurn) is globally <br />problematic and requires multiple projects and <br />partners to work together to restore and maintain the <br />functionality of the various stream channels. <br />Until other projects upstream and downstream of the <br />bridge take place replacing the bridge is not <br />recommended. Channel improvements must be <br />done, replacement and management of the <br />Naneum/ Wilson split must occur, interaction <br />between Naneurn Creek and the Hiline canal must be <br />resolved all prior to a new bridge being installed <br />otherwise, the issue will only repeat itself in time. A <br />new bridge can be built wider and higher to allow <br />more capacity in the current state, but if sediment <br />transport continues as it has, it will just be a matter of <br />time until we are facing the same issue again. <br />Funding a bridge replacement will also be <br />challenging, since Public Works would seek BRAC <br />('Federal) funding grants, which are competitive, this <br />bridge will not be the best candidate due to low ADT <br />(50 cars a day) and short detour routes available <br />nearby makes the likelihood of success very low. <br />Public Works recognizes that if the bridge is to <br />remain in service (in a single lane configuration); <br />continual maintenance will be required and will <br />continue to be one contributor to the overall system <br />wide problem. It is understood that flooding to <br />surrounding residents will not be eliminated by the <br />removal of the bridge but its removal may provide <br />some relief. <br />At this time the overall impact to road users is <br />unknown due to the lack of time to complete public <br />outreach. The rapidly evolving nature of this year's <br />flood events, required engineering research, and <br />