Location: Dillingham, Alaska
Project Dates: 2012-2014
Owner: State of Alaska Department of Transportation and Public Facilities
Contract Amount: $9,109,265 and $5,598,065
Project Details: Both projects resurfaced roughly 2.5 miles of paved road each. Many areas were upgraded with safety improvements including widening of shoulders, guardrail, and pathway construction with separation devices. Many thousands of feet of varying diameter culverts were installed to facilitate drainage through both projects, ultimately feeding the Nushagak River.
The design emphasized improving the road’s drainage structures to handle seasonal runoff and area-wide flooding. This required certain sections of the road to be elevated allowing for larger culverts. In areas of concentrated drainage, the road was built up over 5 feet. The existing culverts were removed and replaced with much larger (15+ foot diameter) multi-plate structures that had to be constructed in place. This required damming and extensive de-watering and abiding by strict fish windows and regulations. Earthen dams were used to keep tidal water from the construction site in combination with upstream water pumping and rerouting. Embankment stabilizing devices, such as riprap and filter blankets on embankment slopes, were installed to mitigate any construction sediment runoff.