Landau Associates provided cultural resources services among other support services for a new sewer interceptor for the Alderwood Water and Wastewater District and the King County Wastewater Treatment Division.  Eleven routing alternatives were originally developed and evaluated in an initial study using many different criteria from three major categories: engineering, community/environmental, and land/easement acquisition.  A preferred route was selected from this study that had the best overall combination of engineering characteristics and minimized community and environmental impacts.

The 3.1-mile long selected route consists of 21- to 48-inch diameter sewer pipe. This route includes 14 microtunnels, and involves multiple crossings of North Creek and unnamed tributaries to North Creek.  As part of the cultural resources work, Landau Associates examined sediments derived from deep geotechnical borings and monitoring wells to obtain stratigraphic information.  Shallow (up to 1 meter below ground surface) subsurface testing was conducted in unpaved areas along the project route.  Landau Associates identified a dual component (prehistoric and historic) archaeological site in the project area and is currently monitoring ground disturbance for archaeological materials in high probability areas.