AEG Event 1/16/25: Tunnel Alternate in California

  • 16 Jan 2025
  • 6:00 PM - 10:00 PM (EST)
  • 60 Cottontail Lane, Somerset, NJ 08873

Registration


Registration is closed


DINNER MEETING ANNOUNCEMENT

Tunnel Alternative Selected for Last Chance Grade,
Del North County, California


January 16, 2025
At the Clarion Hotel in Somerset, New Jersey

Ciancia Mala, P.G., CEG, HNTB Corporation


Last Chance Grade Project Site (Courtesy of Caltrans)
  

Time:
Social Hour 6:00 pm – 6:45 pm    /    Dinner 6:45 pm – 7:45 pm
  

Presentation begins at 8:00 pm
   

 
Place:
Clarion Hotel         60 Cottontail Lane, Somerset, NJ 08873         (732) 560-9880
 
RSVP:
End of Business, Tuesday, January 14, 2025.  A timely RSVP is appreciated!


Please note, you can register more than one individual at a time!
Don't forget to add the event to your calendar from our website!
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Cost:
In-Person Registration Fees
$40 for AEG members  
/  $50 non-members  /  $5 for students with RSVP  /
Professors attend as our guests at no charge.


Remote Attendance Registration Fee - $15.00 (no LSRP CEC credits will be offered for remote attendance)


ABSTRACT

In June 2024, the California Department of Transportation (Caltrans) selected an alternative that includes a 6,000-foot tunnel as a long-term solution for a landslide-prone coastal stretch of U.S. 101 known as Last Chance Grade.  The highway is a vital artery in Del Norte County, connecting Crescent City with communities to the south. An extended roadway closure due to landsliding would require a 450-mile detour.  Both culturally and environmentally sensitive, the project area is a World Heritage Site in Redwood National and State Parks, with stands of large-diameter, old-growth redwood trees. 
 
HNTB and Kleinfelder have been supporting Caltrans in studying and characterizing site conditions and advancing alternative designs for a permanent solution to improve reliability, reduce highway maintenance costs, and protect the area’s economy, natural resources, and cultural landscapes.  The selected two-lane highway tunnel alternative would bypass the majority of active slide zones, reduce the impacts of coastal erosion, and minimize potential effects of climate change.

This presentation will summarize results of efforts to characterize the complexities of the site’s Franciscan Complex geology and its multiple types of nested landslides, irregular groundwater regime, and high seismic hazard potential. These factors, as well as the site’s cultural and environmental sensitivities, bring special challenges for tunnel design and construction.  Among these are the limited access for subsurface investigations, requirements for alignment selection and space proofing, and a portal approach structure in an active earthflow. As currently conceived, the two-lane tunnel would be a single curvilinear bore constructed using the Sequential Excavation Method (SEM). Construction is anticipated to begin in 2030.

BIOGRAPHY

Mala Ciancia is Principal Engineering Geologist and Senior Technical Advisor for HNTB Corporation’s National Tunnel Practice. She specializes in subsurface exploration and ground characterization and works with clients nationwide to provide innovative solutions and risk management for tunnel projects across the U.S.

Ms. Ciancia has more than 40 years of diversified experience in engineering geology, including soil and rock laboratory testing, slope stability, hydrogeology, environmental assessments, and quality assurance for tunnels, power plants, dams and reservoirs, pipelines, building foundations, and borrow sources. She earned an AB in Geological Sciences from Cornell University and an MS in Engineering Geology from Purdue University.  She is a licensed professional geologist in New York, Indiana, Delaware, Louisiana, and California.

 







 

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