Crux Subsurface employees drilling geotechnical holes for the US 89 landslide investigation
Geologic Hazards

U.S. 89 Landslide Exploration

Specialty drilling contractor Crux Subsurface recently completed geotechnical drilling for Kleinfelder at the site of a large landslide near Page, Arizona. Crux completed 17 holes to depths up to 250 feet using a combination of […]

Geologic Hazards

US 89 Bitter Springs Landslide Video Updates

US89DrillingYouTubeThumbSince I last posted about this landslide, ADOT has added several videos to their YouTube channel.  It’s clear that this highway is going to be closed for the long term.  ADOT and their on-call geotechnical consultant tasked with this project, Kleinfelder, are currently drilling boreholes to attempt to characterize the failure surface and determine what the geometry of the failure surface is.  They are installing at least 10 inclinometers to try to determine the location of the slip plane or planes at depth and they have two extensometers to measure if any additional movement occurs.  They are also performing LIDAR surveys as well. Check out the videos below.

Initial ADOT Video Describing the Failure

Click through for the videos!


Geologic Hazards

Landslide on Arizona SR 87 Closes Highway

On March 21, 2008 a landslide caused the closure of Arizona State Route 87 between Payson and Phoenix near mile post 224. So far there are no official estimates as to the size, but based on aerial photos, it appears to be at least 50,000 sq-ft in plan. The offset at the head scarps was approximately 2-meters (6.6-ft) according to AZGS Geologists on site. It appears to have been a rotational slide as the toe of the landslide heaved the southbound roadway up by as much as 1-meter (3.3 ft). There was an existing soil-nail retaining wall on the slope that was destroyed by the slide as well.  Lateral deformations can be seen in photos of the median barrier and the roadway striping. The deformations extended into the northbound lanes as well. More photos and links after the break. (Photo by ADOT)


Standards and Codes

Changes in Geotechnical Engineering Practice in Arizona

[Editor] Note: NCS Consultants, LLC is Randy Post’s full time employer…ie. my day job! [/Editor]

There are some significant changes being made to the state of the practice in geotechnical engineering in Arizona. NCS Consultants, LLC has prepared three policy memoranda for the Arizona Department of Transportation or ADOT that have been issued to consultants all over the State. These memos are on the topics of bearing capacity and settlement of spread footings and retaining walls, the design of drilled shaft foundations in gravelly soils, and the preparation of drilled shaft axial capacity charts for use by bridge engineers.

Although primarily applicable to upcoming ADOT projects implementing the AASHTO 2007 LRFD code, the memos will have a ripple effect down through other local agencies within the state who frequently defer to ADOT guidelines for geotechnical engineering. Also, the memos and the ADOT/NCS approach to LRFD implementation in geotechnical engineering were presented by NCS at the 2008 TRB Conference in Washington D.C., and many other state DOTs and the FHWA were very excited about the memos. The approach used if not the exact content may become a model for other agencies. More info and links to download the policy memoranda are provided after the break.