The Seattle office provides multiple related service lines to clients at local, regional, and national levels. In the Northwest, Terracon specializes in geotechnical engineering, environmental consulting, and construction materials engineering and testing services. Terracon’s basic strength is our commitment to our local clients; we are proud of our commitment to the Northwest region. The senior engineering staff of Terracon’s Washington offices offers more than 250 years of local experience.
After operating in the greater Seattle area and Portland, Ore., since 1998, Zipper Zeman Associates, Inc. joined Terracon in 2005. These local offices officially became Terracon in 2009. RGA Environmental joined Terracon in 2014, and in 2015 the Seattle location joined Terracon’s Mountlake Terrace office, further expanding services from this location.



21905 64th Ave. W., Suite 100 Mountlake Terrace, WA 98043
Phone: (425) 771 3304
Fax: (425) 771 3549