Salmon Creek Water Treatment Plant Outfall Vancouver, Washington
In decommissioning an aging outfall, the alignment of its replacement required the crossing of various obstacles including property lines, utility infrastructure, and multiple bodies of water. Utilizing various land survey tools, the Otak team established an extensive survey control network to navigate each of these elements across the entire process on the way to completed construction.
Extensive Land Surveying to Navigate Numerous Site Challenges
After nearly 55 years of service, an existing treated effluent outfall to the Columbia River was decommissioned, creating a need for its replacement. The new design presented numerous site challenges with the need to cross various infrastructure, property, and natural barriers. This included a BNSF railroad that carries 60+ trains per day, two state highway rights of ways, and three state-owned bodies of water – Salmon Creek, Lake River, and the Columbia River. It would also cross two major fiber optic lines and an 18-inch liquid petroleum line. To address these obstacles, land surveying work established an extensive survey control network with the retracement of dozens of property lines and easements with topographic mapping of the existing outfall, the proposed outfall alignment, and all existing access roads. A comprehensive set of land surveying tools, including traditional ground surveying, LiDAR scanning, UAV aerial photogrammetry, and a bathymetric drone, were utilized. Survey work continued throughout design and accounted for dozens of potholes, natural resource and archeological area mapping. Preparation of these extensive materials for the acquisition of easements from land owners involved extensive collaboration with the Washington State Department of Natural Resources, Burlington-Northern Santa Fe railroad, adjacent homeowners associations, and the US Coast Guard. As construction progressed, QA surveying and alignment checks were provided, mapping the location of the constructed pipeline, and performing as-builts of the underwater trench for the pipeline and diffuser in the Columbia River.
