Ants from Space

 While preparing for a soil exploration in the Spanish Springs Valley (north of Sparks in Washoe County), I noticed an unusual pattern in the Google Earth imagery.

As seen in the image to the right, roughly every 50 feet there is a clearing between the sage brush.

At many of these clearings, it appears a small lighter-colored dot may be located at the center of it.





Difficult Site Access 2014Marvin Davis Difficult Site Access

MDA has made a specialty of working on hard-to-access Lake Tahoe project sites.


Many sites are inaccessible to site exploration in winter, both due to snow cover and Tahoe Regional Planning Agency restrictions on grading between October 15 and May 1 of each year.


For typical residential sites under these conditions, we may do preliminary evaluations based on ReMi shear-wave velocity surveys and dynamic cone penetrometer; some sites we have worked on defy conventional exploration even in the summer and have required the use of similar methods.

Meadowood Mall Pile Driving 2016Marvin Davis Meadowood PileDriving0

In the beginning of March, we observed pile driving for seismic foundations for a new Dick’s Store at Meadowood Mall. This was a project that Jonathan had brought along from his previous employer – to finish the foundation recommendations and consult on the pile driving operations.


The foundation soils under the site included intermittent areas of liquefiable sands, at about 20 to 27 feet below ground surface – possibly a buried stream channel – generally surrounded by less liquefiable clayier or denser soils. At the south corner of the proposed new store, liquefaction settlement were predicted in the range of 3 inches. There was less than 1 inch of liquefaction settlement predicted at most other locations. To accommodate this geological problem, rather than require mitigation of the entire store foundation, piles were put under the walls and columns in the south corner, for a total of 17 piles. Tie beams are planned between the pile supported column locations. The rest of the store is supported on conventional spread footings with minimal foundation ties except the normal strip foundation under the perimeter wall.

Ward Creek Stream Bank Restoraton in 2015-2016Marvin Davis Ward Creek0

The picture to the right is of a completed portion of a stream bank restoration project which Marvin Davis & Associates has been involved in, on and off, for several years.

The project is on Ward Creek, which discharges into Lake Tahoe. MDA developed the project (with geomorphology input from Cardno, landscaping (not yet installed) by High Desert Landscaping, and with the owner’s permitting consultant, Agan Consulting), prepared plans, and provided responses and revisions to meet the permitting agency requirements (Tahoe Regional Planning Agency, Lahontan Water Quality Review Board, Army Corps of Engineer, Placer County, Fish and Game). The project as shown is complete, but prior to replanting; the young cottonwood in the far bank was protected in place and rock placed around it. This portion of the creek regularly runs dry in late fall, as what water there is in the upstream reaches sinks into the permeable alluvial fan.

Welcome Jonathan W. Pease, PhD, PE, GE

Marvin Davis & Associates, Reno, Nevada, is pleased to announce that Jonathan Pease, Ph.D., P.E. has joined the firm as an Associate engineer. Dr. Pease has over 20 years of experience in geotechnical engineer in California and Nevada, and has worked in Reno since 2003. His recent projects in Reno have included the new Southeast Connector Bridge over the Truckee River, geotechnical investigations for additions to the Veteran’s Affairs Hospital in Reno, geotechnical investigations for Meadowood Mall additions, and design support for the Truckee River Flood project with HDR. Areas of expertise include deep as well as conventional shallow foundations, liquefaction assessment, and ground improvement.

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