Orange County Branch Newsletter

September 2016

Geo-Institute

ARTIC: Anaheim Regional Transportation Intermodal Center


By Mr. Michael Givens, PhD, PE, PG, ASCE OC Geo-Institute First Director

The ASCE-Orange County Geo-Institute (GI) hosted a luncheon on August 16, 2016 at the University of California, Irvine (UCI) University Club. The luncheon, which was attended by over 40 people, consisted of a presentation on the geotechnical design aspects of the Anaheim Regional Transportation Intermodal Center (ARTIC) project. ARTIC is a uniquely designed public transportation facility in Anaheim, California that provides rail, bus, taxi and other services for daily commuters, visitors, and leisure travelers. The presentation was given by Mr. Allen Yourman, PE, GE, who is a Principal Engineer and co-founder of Diaz●Yourman & Associates, Inc. in Santa Ana, California.

The ARTIC site is in close proximity to the Santa Ana River and was formerly occupied with a County of Orange work yard consisting of outdated building structures that were located within portions of the proposed improvement footprints. Further complicating the subsurface soil conditions was an in-filled former quarry encompassing about half of the property. The primary geotechnical issues for the site included variable thicknesses (5 to 20 feet) of undocumented fill in the former quarry; potentially liquefiable and laterally spreading soils; and groundwater flooding from the Sana Ana River.

Mr. Yourman discussed the inherent risks associated with the geotechnical issues and how they were addressed for the primary feature at the site: the main terminal building. The lack of consistency and variable density of the undocumented fill along with the large building loads presented a potential risk that may not have been easily addressed by typical removal and recompaction efforts. The project team members reviewed several foundation alternatives and ground improvement solutions and agreed on a mat foundation system supported by ground improved using deep dynamic compaction (DDC).

As part of his presentation, Mr. Yourman described the general process of DDC ground improvement, discussed the recommended DDC drop weight, drop height, the spacing between drop points, and the number of drops and passes. Mr. Yourman explained briefly how DDC ground improvement is performed by specialty contractors, and how the Geotechnical Engineer of Record is tasked with recommending quality control design specifications that must be met for the integrity of the design. The presentation included quality control results of pre- and post-improvement Standard Penetration Tests (SPT) and CPT cone resistance indicative of soil density along with their recommended design line requirements.  Mr. Yourman also explained how DDC was successful in identifying and compacting an area on the site that was loosely backfilled with bricks and rubble located in one of the proposed footings.

Mr. Yourman's presentation also consisted of several remarkable site photographs showing the DDC ground improvement operations and main terminal building construction and is included here:

On behalf of the ASCE OC GI and my fellow board members, I would like to thank Mr. Yourman for his contributions to our event. Lastly, I would like to offer special thanks to our luncheon sponsors: Hayward Baker Geotechnical Construction, Western Ground Improvement, and Tencate Mirafi.

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