Geotechnical Field Work: Beverly Hills Area
Metro contractors are preparing to conduct a series of geotechnical field tests in the Beverly Hills area as a part of the Final Environmental Impact Statement/Environmental Impact Report (Final EIS/EIR) for the Westside Subway Extension. This work will build on the data gathered during the Draft EIS/EIR for the project and provide further soil and seismic information along the route of the Locally Preferred Alternative (LPA). In certain areas, noise and vibration tests will also be conducted. Following the tests, the data will be analyzed and used to make further informed decisions about subway construction.
Monday, April 25, 2011 through Friday, April 29, 2011 from 9:30am-4:00pm Metro contractors will conduct work at the following locations:
- Wilshire Boulevard east of Hamilton Drive
- Wilshire Blvd east of Robertson Blvd
Note: Should any work need to be cancelled and rescheduled, Metro will inform you of new work date(s)/time(s).
The equipment to be used during the field testing is described below:
The rotary-wash borings will be drilled to obtain soil samples for testing and evaluation, and at some locations to install soil gas monitoring wells. The borings will be drilled using truck-mounted rigs operated by crews consisting of up to four personnel. The drill bit will be advanced to depths of 80 feet or greater. Drilling fluid consisting of bentonite slurry will be pumped into the borehole and circulated into a wash tub at the ground surface, where cuttings will be removed prior to re-circulating the fluid through the hole. Soil sampling will be performed at 2½ to 5-foot vertical intervals by advancing a sampler using an automatic hammer. At the conclusion of drilling, the slurry will be placed in drums, tested for adverse chemicals, and disposed of off-site. The drums will be removed from the work site on a daily basis, prior to the end of each work period. The borehole will be filled with grout and its top patched with asphalt to match the surrounding grade.
What to Expect During Rotary-Wash Drilling:
- A drilling crew consisting of up to 4 personnel per rig.
- A truck-mounted drill rig (see photo) and truck equipped with additional drilling supplies.
- Wash tub to collect and circulate drilling fluid at ground surface during drilling operations, and drums to contain drilling fluid for sampling and disposal at conclusion of drilling.
- Parking lane and/or one lane of traffic will be blocked while work is under way on residential streets, and up to two lanes on business/arterial streets.
- Moderate noise and moderate vibration.
- Lanes will be cleared at the end of the work period and re-opened for regular use.
" Mini-Vib " Truck Seismic Surveys: Equipment to be used will consist of a "Mini-Vib" truck, seismograph recording truck, cable sensors, electric generator and a geophysical survey crew of up to 6 people. Sensors will be placed along the street. Approximately every five feet, the truck will place a "plate" on the surface of the street, then, vibrate the plate in order to take a reading of the vibrations along the street (see photo). The "Mini-Vib" truck will move through each testing location and remain in front of any given location for about 15 to 20 minutes. Residents may encounter some moderate noise as the truck performs the test. The sound level at a distance of about 50 feet from the truck should be no more 70 decibels, or similar to that of average daytime traffic.
" Micro-Vib " Seismic Surveys: Equipment to be used will consist of a portable "Micro-Vib" vibration source box, seismograph recording truck, electrical generator, cable sensors, and a geophysical survey crew of up to 6 people. Sensors will be placed along the street. Approximately every two feet, the portable "Micro-Vib" box will be vibrated by the electrical generator source (see photo). The "Micro-Vib" box will be moved manually through each testing location and remain in front of any given location for about 20 to 30 minutes. For "Micro-Vib" box testing, the sound level should be no more than 60 decibels, or similar to light daytime traffic.
Other Important Information:
- All work has received necessary permits and approvals.
- Additional fieldwork following this testing is anticipated. We will inform the area(s) where and when this work will take place.
- For more information about the Westside Subway Extension, please leave a message at 213.922.6934 or online at www.metro.net/westside.
- For day-to-day testing location updates, please follow us at twitter.com/westsidesubway .
- For emergencies or issues needing immediate attention, please call 323.236.2117