Lakebed Pipeline Dive Inspection and Sedimentation Analyses
King County owns and operates the Kenmore Lake Line Interceptor sewer pipeline (Lake Line) located offshore the north Lake Washington shoreline. This 48-inch pipeline conveys wastewater from Seattle’s northern communities to a pump station at the western side of the lake and onto the West Point Treatment Plant on the shores Puget Sound.
King County Wastewater Treatment Division, Department of Natural Resources and Parks, selected Lally Consulting LLC as part of a multi-disciplinary team to evaluate the role the Lake Line may have on sediment deposition in its vicinity, and if so, to what extent.
The team conducted a field investigation in the study area, including visual inspection along the length (3,600’) of the pipeline by a Lally engineer-diver for sedimentation observations and location of manhole covers. The team also performed limited depth measurements and sediment coring along eight (8) transects on either side of the Lake Line. Equipment selection was guided by site conditions consisting of shallow water depths, poor visibility, and dense stands of submerged aquatic vegetation.
Lally LLC performed a limited desk study to evaluate the potential for sedimentation impacts in the vicinity of the Lake Line, including assessment of site geomorphological, lake level, wind, and wave regime, and sediment transport processes. Findings were summarized in a report and submitted to the client.
Services Provided
Supply GPS, Sediment Coring, Depth Sounding, and SCUBA Equipment
Engineer-Diver Survey
Sediment Sampling
Lacustrine Hydrodynamic and Sedimentation Processes Evaluation
Contribute to Graphics and Report Preparation
Location
Seattle, Washington