Shoshone Drainage; Replace and enhance culvert systems

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Other Agencies with Actions or Authorizations: California Department of the Interior, Fish and Wildlife Service Description: The California Department of Transportation (Department), as assigned by the Federal Highway Administration (FHWA), is the lead agency under the National Environmental Policy Act (NEPA). The Department is the lead agency under the California Environmental Quality Act (CEQA). The existing culvert system at State Route (SR) 178, post mile 43.4, in Inyo County, CA (Figure 1) contains two separate drainage systems (OS 1 and OS 2) to accommodate the two main drainage paths within the Amargosa River channel. The westernmost culvert (DS1) is located at PM 43.39, and the eastern culvert location (OS2) is located at PM 43.44 (Figures 2-4). A survey of the existing culverts has determined that the culverts have exceeded their recommended 25 year design service lives, and due to sediments deposited by the river are only operating at 25%-50% of their original capacity. This project proposes to replace both sets of culverts (OS1 and DS2) with pre-cast concrete box culverts to increase hydraulic capacity and reduce the frequency of water overtopping the highway.

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