Sonora Drainage IV along SR 108 in Mono County

Sonora Drainage IV along SR 108 in Mono County

The project will improve a thirty drainage facilities along Route 108, which are incapable of handling moderate to heavy runoff, causing flooding, road closures, and potential damage to the highway. Because of flooding, maintenance crews spend much of their time and effort scraping mud off the road, replacing embankment, and controlling traffic. The proposed drainage facilities. Work will include replacing existing drainage culverts, extending the inlet and/or outlet of existing culverts, placing drainage inlets, placing flared end sections on the ends of culverts, improving roadway shoulders, and placing rock slope protection. Ten sites are expected to have flowing water at the time of construction (summer/late fall). Approximately 5.0 sq. meters (about 1/1000th of an acre) of potential Corps jurisdictional wetlands will be impacted. Avoidance and minimization measures include limiting the construction area and installing ESA fencing to protect sensitive sites. Overall, the project will reduce impacts to wetlands by increasing the distance from the road that water is released to wetlands (reducing nonpoint source pollution from the road to wetlands), reducing the need for culvert maintenance which may impact wetlands, and reducing culvert overtopping which causes siltation and erosion. Stormwater best management practices will be emploed during construction to reduce erosion and siltation.

Mono