HWA provided geotechnical engineering evaluations in support of the upgrades to lift stations 16-18 and conveyance improvements on 17. Tasks included a geotechnical engineering study, exploratory borings, and testing on selected samples to characterize relevant engineering and index parameters of the site soils. HWA performed engineering analysis, laboratory testing, and specific design and construction considerations for each site (seismic and landslide hazard areas were also addressed).

HWA provided geotechnical engineering design services for the South Pump station located along the Duwamish River. The proposed pump station also included construction of several structures, many of which extended a significant distance below the existing grade. HWA assisted SPU’s geotechnical engineering team with the suitability of mitigating for liquefaction using deep soil mixing due to the fine-grained nature of the soils. Following design, HWA provided special inspection of install.

HWA provided geotechnical engineering studies to evaluate the soil and ground water conditions in the vicinity of the existing lift station and provided recommendations for design and construction of the improvements. Work included site reconnaissance, subsurface investigations, and geotechnical engineering analyses. Field work included exploratory borings and installation of a monitoring well, with subsequent checks for groundwater as well as lab testing on selected soil samples.