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710 Tunnel Study

710 Tunnel Technical Study Information

Frequently Asked Questions

SR-710 Tunnel Technical Study FAQ


What is the purpose of the Study?


The purpose of the Study is to consider all practical routes for extending the SR-710 using a tunnel based on soil and subsurface conditions in the study area.


What cities are in the Study area?


The Study area includes the cities of Alhambra, Glendale, La Cañada Flintridge, Los Angeles, Monterey Park, San Marino, Pasadena and South Pasadena.


How are the cities participating in the study?


Each city has appointed one representative and one alternate to the Steering Committee and the Technical Advisory Committee.


What is the role of the Steering Committee?


·    Provide input and advice to Caltrans.

·    Receive presentations about tunnel technology to become “community experts.”

·    Review reports and other information developed by the Study.

·    Serve as informed spokespersons.

·    Steer the Study on a route neutral path.

·    Bring forward community values, questions and concerns.


What is the role of the Technical Advisory Committee?


·    Review technical data, reports and other information developed by the Study.

·    Provide technical guidance to Caltrans staff, the consultant team, and the public.

·    Provide input to the Steering Committee.


Is a freeway going to be built?


There is no plan to build a freeway at this time.


Where is the tunnel going to be built?


There is no plan to build a tunnel at this time. Extensive environmental studies would have to be completed to define a tunnel project.


Is the Study part of an Environmental Impact Report?


This is not an environmental assessment. We are only studying soil and subsurface conditions.


Exploration Program


What is the Exploration Program?


The Exploration Program involves research, exploration and technical analysis of the soil conditions found if tunneling at depths of 250 feet or greater.


What will the data collected reveal?


The information gathered will describe soil and sub-surface conditions in the Study area.


What types of testing are you conducting?


We are conducting two types of tests:


Borings: Information about various soil types, such as rock or sand will be gathered by drilling (boring) deep into the ground.


Geophysical Line Testing: Information will be gathered by taking an electronic image of rock layers, near-surface faulting, sub-surface voids, and bedrock elevations along a specific area.


Where are the testing sites?


Sites are located in the cities of Los Angeles, Alhambra, South Pasadena, Pasadena, and San Marino. The testing sites were grouped into 5 zones to organize and identify each site by geographic location.


Why are you testing in such a large area?


The Study is being conducted in a route neutral manner. This means all reasonable and practical options for extending the SR-710 using a tunnel are being considered.


Who authorized the testing in these cities?


The exploration team obtained drilling permits from all of the cities involved in the Study area to conduct the testing.


When will the data collected become available to the public?


Data will be available to the public by Fall 2009. Contact the SR-710 Technical Study Office or log on to our website at www.710tunnlestudy.info for more details.


Exploration Program Testing 


When were borings being conducted?


Borings were conducted Monday-Friday between the hours of 7:00 a.m. and 5:00 p.m. Boring activities started in January 2009 and were completed in May 2009.


How long did each boring last?


Each boring lasted between 10-15 days, depending on depth, weather and equipment functionality.


How long did geophysical line testing last?


Each geophysical line test lasted one day over a 12 hour period. Geophysical line testing was completed April 2009.


Why was geophysical line testing done at night?


We preferred to test during the night time hours because there was less noise in the area. A lower noise level gives a better electronic image of soil conditions.


How was the public notified about the testing?


Residents and businesses were contacted by a door-to-door canvassing program. You can also contact the SR-710 Technical Study Office or log on to our website at www.dot.ca.gov/dist07/710study/ for more information.


Outreach Program


How will you provide information to the public?


We have outreach staff that is conducting community meetings, presentations to organizations, and is participating in community events to provide information to the public.


Do you have a website?


Yes. You can visit our website at http://www.dot.ca.gov/dist07/710study/


Where is your office located?


The office is located at:


3412 N. Eastern Avenue

Los Angeles, CA 90032


What are your office hours?

We are open Monday-Friday 8:00 a.m. - 5:00 p.m.

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