Field Work - April 9-18

Geotechnical Field Work: Fairfax Area

Metro contractors are preparing to conduct a series of geotechnical field tests in the Fairfax area as a part of the planning for the Westside Subway Extension.  This work will build on the data previously gathered during the Draft EIS/EIR and Preliminary Engineering Phases for the project and provide further soil and seismic information along the route of the Locally Preferred Alternative (LPA).  Following the tests, the data will be analyzed and used to make further informed decisions about subway construction.

Monday, April 9 through Wednesday, April 18 from 9:00am-3:30pm (weekdays only) Metro contractors will conduct work at the following locations:

• Wilshire Blvd west of S. Dunsmir Ave
• Wilshire Blvd west of Fairfax Ave.
• Wilshire Blvd west of McCarthy Vista
• Wilshire Blvd east of Citrus Ave.

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:

Rotary-Wash Drilling

The rotary-wash borings will be drilled to obtain soil samples for testing and evaluation. 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 90 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 bentonite slurry and soil cuttings 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.

Continuous Core Drilling

Continuous core drilling will consist of two methods: hollow-stem coring and rotary coring. Hollow-stem core borings will be drilled using a truck-mounted drilling rig advancing a core barrel into the ground by spinning a 6- to 8-inch diameter casing with a drill bit into the ground to collect samples of the various soil layers. No drilling fluid will be used for hollow-stem coring. Rotary core boring operations will consist of a truck-mounted drilling rig advancing a core barrel into the ground while circulating drilling fluid through the hole, similar to rotary-wash drilling. After the exploration is completed, the soil cuttings generated and slurry used during drilling will be placed in drums, tested for adverse chemicals, and disposed of off-site on a daily basis. As for all borings, the work areas will be scanned for utilities prior to drilling, and the upper soils will be hand augered. At the conclusion of drilling, the hole will be filled with grout and its top patched with asphalt to match the surrounding grade. There will be two to three support trucks for the drilling process.  Parking lanes and traffic lanes will need to be coned off during work.

What to Expect During Continuous Core Drilling:

• A drilling crew consisting of up to 4 personnel per rig.
• A truck-mounted drill rig and support trucks (see photo).
• For rotary core drilling, a 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.
• For hollow stem drilling, drums to collect soil cuttings for sampling and disposal at conclusion of drilling.
• Parking lanes 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.

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 323.889.5311