Industrial Geotechnical Engineering

Tongue River Railroad

The TRR will connect the BNSF main line along the Yellowstone River at Miles City, Montana, to Sheridan, Wyoming, comprising a new line 119 miles long through the rugged terrain of the Tongue River Breaks. Cuts and fills up to 250 feet high will be required. WAI organized and led the geotechnical team, which included two other Montana firms. As many as 10 drill rigs were running at a time during the field investigation. As the project moved into the design-build phase, the team remained in place under the overall leadership of URS Corp; WAI organized the field efforts and provided senior geotechnical review. Among many other tasks, WAI prepared stability analyses for the large cut slopes using non-linear rock strength parameters and analyzed shrink-swell issues involving the extensive “burn” deposits along the rail. At the present time, WAI is leading vibration monitoring at the Miles City State Fish Hatchery, to assure that construction and operation will have no detrimental effects on the rare and endangered pallid sturgeon. Our teammates for the hatchery project include Shannon & Wilson to address fisheries issues and Wilson Ihrig to provide high resolution vibration and noise monitoring. The completion of the EIS is at hand and construction is scheduled for spring 2008.

PPL Montana, Colstrip

PPL’s Colstrip power plant is the second largest coal-fired facility west of the Mississippi, producing 2,000 megawatts. Low-sulfur coal and stack scrubbers help the plant meet and exceed EPA emission standards. Fly ash effluent from the scrubbers is discharged to large impoundments with clay-core earth dams and a slurry cutoff wall about 5 miles long, partially founded on rock altered by burning of a coal seam. WAI has worked with Hydrometrics on many projects here since 1990, including investigation and remediation of seepage problems and dam safety. The embankments are instrumented with piezometers and slope inclinometers. WAI also recommended and performed geotechnical design for two new paste facilities, which separate solids and liquids in the effluent stream, reducing seepage pressures against embankments.

ASARCO SXEW Facility, Ray Mine, Arizona

The solvent extraction and electrowinning plant at Ray processes acid copper solutions from leach operations at the huge mine. Over the years, sulfuric acid has caused solution problems in the subgrade, leading to differential movement of the plant foundations and slabs. WAI worked with Hydrometrics to provide geotechnical exploration, analysis of the complex interaction of gypsum formation and solution, and long-term monitoring, including slope inclinometers, extensometers, and tilt meters.