The project is currently in the exploration/design phase. Along with utility locates, site exploration, and soil testing, this phase included conducting a geotechnical probe. The probe provided essential information on how the geology beneath the river will impact construction. Conducting the geotechnical probe helped us determine the best tools to use for the future pipeline and the best path across the river.Design phase 1: Pre-construction activities (complete)
Soil sampling: On the east and west sides of the river, crews dug in the street, sidewalk, and public right-of-way to find the exact locations of underground utilities and assess conditions at the site. After completing exploration, we restored those streets and sidewalks with similar materials.Preparing “Block J” (1720 SW Naito Parkway): Crews fenced off the parking lot at Southwest Naito Parkway between Harrison and Market to prepare for the geotechnical probe. They dug a 30-foot-deep hole in the parking lot, and placed the drill in the hole. The drill has since been removed, as the geotechnical probe is complete.Geotechnical investigation: We needed to know what’s underground before going “full bore.” Drilling a geotechnical probe helped us identify the types of soil and rock deep underground. A 12-inch-diameter probe drilled a pilot hole from the parking lot on the west side toward the east. The computerized drill bit sent information to the surface about what it encountered. This process helped us understand the next steps we need to take.The geotechnical probe followed the same path we expected a future horizontal directional drill to follow, shown as the blue line above.Design phase 1A: More investigation (current)
By performing the geotechnical probe, we discovered that the soil along our proposed route couldn’t be drilled through with the technology we were hoping to use. We expect to do more vertical borings in the area to better understand the soil conditions underground. Doing this additional geotechnical exploration and analysis will take about six months. This geotechnical work will tell us whether we need to adjust the route or tunneling methods we plan to use.
We’re also continuing to prepare the areas where we will connect the new pipe.