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Core samples gathered from the boring sites willbe analyzed and will provide information about the type of rocks and other materials present at 200 to 300 feet below the surface.

Geotechnical Tests Begin for the Route 710 Tunnel Technical Study
by  Maria Raptis
Issue Date: 02/2009

“The geotechnical activity and testing is not to predict a route, the testing is to determine if there are any zones that we should not consider at all,” said District 7 Director Doug Failing.

In January, Caltrans District 7 began the geotechnical exploration program as part of Route 710 Tunnel Technical Study. Borings and seismic reflection testing activities will take place at approximately 33 locations throughout the study area through early May, as weather permits, in the cities of Alhambra, Los Angeles, South Pasadena and Pasadena.

Caltrans, in cooperation with the Los Angeles County Metropolitan Transportation Authority (Metro), initiated the study in spring 2008 to examine the geotechnical feasibility of a tunnel to connect the northern termini of Route 710 in Alhambra to the Foothill Freeway (I-210). This two-year study, now heading into its second year, builds upon the findings of the 2006 Tunnel Feasibility Assessment Study commissioned by Metro, which concluded that the construction of a tunnel is feasible.

Caltrans held a press conference on January 6, the first day of drilling, at the first boring site in the City of Alhambra. District 7 Doug Failing’s public message was that the purpose of this study is not to determine where a tunnel should be constructed, but to investigate where it should not be built, if there is future tunnel construction. Caltrans’ Geotechnical staff demonstrated just how non-invasive the boring is --- only 4 to 6 inches in diameter, but up to 250 feet deep, nearly the height of Los Angeles City Hall.

“What we are doing today is our commitment to the community. We’re looking to see what is underground. The geotechnical activity and testing is not to predict a route, the testing is to determine if there are any zones that we should not consider at all,” said District 7 Director Doug Failing.

Route 710 ends on Valley Boulevard near the borders of Los Angeles and Alhambra; it resumes at Del Mar Boulevard in the City of Pasadena and continues 6/10 of a mile north where it meets I-210. Motorists who continue traveling north do so on local streets through the cities of Alhambra, Los Angeles, South Pasadena and Pasadena.

In addition to funding the geotechnical and public outreach contracts, the $11.4 million study establishes two committees: a Steering Committee and a Technical Advisory Committee comprised of appointees from each jurisdiction and agency to establish their own guiding principles and review the technical findings and data. A team of tunnel technical advisors, who are considered to be experts in tunneling technology, serve as resources for the committees. The study is being conducted in a route neutral manner, meaning that all reasonable and practical alternatives for completing the route are being considered within the study area, which encompasses the cities of Alhambra, Glendale, La Cañada Flintridge, Los Angeles, Monterey Park, San Marino, South Pasadena and Pasadena.

Funding for the study comes from a combination of sources, including $5 million from Metro, $4 million from Caltrans and $2.4 million in federal funds from a Congressional Resolution (122 STAT. 1592) sponsored by Congressman Adam Schiff (29th District), which states, “….710 Freeway Study to comprehensively evaluate the technical feasibility of a tunnel alternative to close the 710 freeway gap, considering all practicable routes, in addition to any potential route previously considered, and with no funds to be used for preliminary engineering or environmental review except to the extent necessary to determine feasibility.”

The study does not examine or consider environmental impacts nor is it part of an environmental process.

Community participation is an important component of this study. Caltrans is conducting an extensive education and outreach effort to inform and involve the general public, community leaders and elected officials. Presentations are being given at numerous city council meetings, town hall meetings and neighborhood associations. Community workshops are being conducted where opinions, questions, issues and concerns will be addressed, documented and integrated into the technical portion of the study.

“Our public outreach work throughout the study ensures complete transparency and participation of community representatives, residents and elected officials. Results of the study will be reviewed by the two committees and will be available for the public.” said Deborah Robertson, Caltrans Deputy for External Affairs, who oversees the public outreach program.

The geotechnical phase involves research, exploration and technical analysis of the soil and sub-surface conditions found while tunneling at depths of more than 250 feet. Caltrans and CH2M HILL, the geotechnical contractor for the study, will conduct all of the borings. The exploration is comprised of two integrated activities of boring and seismic reflection.

“Core samples gathered from the boring sites will be analyzed and will provide information about the type of rocks and other material present at depths of 200 to 300 feet below the surface. Seismic reflection testing will provide an electronic image of geologic formations in a specific area as well as information on rock layers, near-surface faulting, sub-surface voids, and bedrock elevations and depths,” says Abdi Saghafi, Caltrans’ project manager for this study. “The study’s findings will provide information about the challenges and opportunities associated with tunneling.”

As of the end of January, Caltrans has completed boring at four sites in Alhambra, Eagle Rock and El Sereno and two seismic refection tests in Alhambra.

As part of the community outreach efforts, information will explain state-of-the art tunnel technology currently in use for highways and how tunnels are built. Public education and outreach includes focus groups, public meetings and discussions. The SR-710 Study Information Office, located at 3412 North Eastern Avenue, Los Angeles, 90032, is open to the public for the latest information about the study, boring and seismic reflection testing schedule and upcoming meetings. The phone number is 323-222-1710; or toll free: 877-710-4111. Visit the website at www.710tunnelstudy.info

The public is invited to attend a townhall meeting on Wednesday, February 25, 2009, from 6:30 to 8:30 p.m., at the South Pasadena Library, 1100 Oxley Street, 91030.

A flood of calls from the media about the boring activity prompted an impromptu press conference to answer all questions at once by District 7 Director Doug Failing (at podium). Boring and seismic reflection testing activities will take place at approximately 33 locations throughout the study area until spring 2009. Councilwoman Sharon Martinez (left) and Mayor Barbara Messina, Mayor of Alhambra (right) joined District 7 Director Doug Failing in support of the drilling and tests as part of the 710 Tunnel Technical Study. Using four rigs, Caltrans Geotechnical Crew and contractor for the study, CH2M Hill, will both conduct the boring and seismic reflection testing.