Location: Portland, Oregon
Client: Confidential Specialty Contrator
Contract Value: $272,226
AEC was subcontracted by a specialty slurry wall installation contractor to perform the installation of erosion and sediment controls, site surveying, excavation and disposal of contaminated material, installation of a groundwater barrier wall cap, and the decommissioning and abandonment of seven (7) monitoring wells. We were proud to team up with the contractor, whose unique technology for barrier wall installation proved to be the best method for this project, given its ability to substantially decrease the overall project schedule and install the wall more efficiently near the shoreline.
The original scope of the project called for our specialty contractor to construct a 453 foot long groundwater barrier wall of bentonite clay material, utilizing their proprietary “mix-in-place” method. After installation of the wall, AEC installed a 6 inch deep by 10 foot wide surface of dense graded aggregate (DGA) over a 5 foot wide by 2 foot deep clay cap. Due to record-breaking rainfall that month and the resulting soil conditions, AEC proposed an alternate cap process of installing DGA the full 2.5 foot depth, underlain by HDPE geomembrane and geotextile material. This liner will prevent the desiccation of the groundwater barrier wall. Additionally, prior to installation the client opted to extend the length of the trench by 100 feet and increased the trench width by 2 feet.
Much to our client’s satisfaction, and despite intense late winter rainfall, AEC wrapped up the project successfully and efficiently following hydroseeding and site stabilization activities.