Location: San Diego, CA
Project Partner: Flatiron-Skanska-Stacy and Witbeck, A Joint Venture
Challenge: Installation of large diameter piling to 260 feet below grade in a lagoon with a top of permanent steel casing 26 feet below grade.
Overview: Condon-Johnson was contracted to install the drilled shafts for a two phase bridge replacement in San Diego. The first phase widens the freeway, then the original freeway is demolished and rebuilt in the second phase. The project consists of 17 each 10 foot diameter pier piles to 245-260 feet below grade and 44 each 5 foot diameter abutment piles to 165 feet below grade.
Results: Condon-Johnson has successfully completed the first phase of abutment piling (22 each) and will soon complete the west side pier piles (4 each). Numerous installation techniques were utilized to construct piles of unprecedented size and depth. Installation techniques included vibrated casing with an APE 600, oscillator and casing with a Soilmec SR-145 with VRM 250KL drill setup for the 5 foot diameter piles and a Liebherr 895 with Buma C3000G crane setup for the 10 foot diameter piles, and slurry displacement drilling with an IMT AF300 for the CMP top cans and a Bauer BG46 to excavate the rock socket portion of the 10 foot diameter piles.
Location: Juneau, AK
Project Partner: Manson Construction Co.
Challenge: Installation of extremely long, high capacity tiedown anchors and large diameter rock sockets in an unpredictable and severe marine environment.
Overview: Condon-Johnson was contracted to install 49 high capacity tiedown anchors for the construction of the new Juneau cruise ship facilities. All of the work was performed over the waters of the Gastineau Channel, off the coast of Juneau.
Results: Condon-Johnson, by working in close coordination with the project partner and owner, was able to complete all the tiedown anchors successfully, and was able to accelerate the project schedule. The tiedown anchors were installed inside pipe piles driven by Manson Construction to bedrock with depths of the pipe pile often in excess of 180 feet. Condon-Johnson then drilled 40 feet into the bedrock and installed the reinforcing bar; tiedown anchor lengths reached up to 250 feet depending on the bedrock quality and elevation. Each tiedown was load tested to 600,000 pounds, and post-tensioned to 500,000 pounds.
The project also called for six 48-inch diameter rock sockets, 20 feet into the bed rock that pipe piles would be driven into to fasten a floating pontoon dock. Condon-Johnson mobilized specialized crew and equipment, including a 48-inch diameter cluster hammer, to successfully complete the rock sockets. The rock sockets were challenging because the rock slope was very steep and near vertical at some socket locations. Further compounding the problems, all drilling occurred in the winter with an average high temperature of 15 degrees plus with wind speeds recorded up to 103 MPH.
Location: San Francisco, CA
Project Partner: Lendlease Construction
Challenge: Design build of a shoring system for a deep excavation at a narrow jobsite
Overview: Condon-Johnson’s package included the site demo, underpinning, dewatering, soil mix cut-off wall, excavation, internal bracing, and permanent tie downs. The site demo and excavation was subcontracted to AB Construction. The shoring and dewatering were design build, designed in house by Condon-Johnson. The tie downs were design assist where Condon-Johnson’s recommended design was included on the structural engineer’s building drawings.
Results: Condon-Johnson worked tenaciously to overcome the inherent difficulties associated with executing a 65 foot deep excavation with soldier piles up to 85 feet in length at a jobsite just 70 feet wide in the congested financial district of San Francisco. Drilling crews worked diligently to install a secant pile wall underpinning an adjacent structure, and utilized cutter soil mixing (CSM) to install a 42,500 ESF (55,600 GSF) impermeable shoring wall. A dewatering system utilizing eight deep well points was designed and installed to effectively dewater the excavation without depressing groundwater outside of the building footprint. The internally braced excavation required pin piles and two trestles to support the installation of three levels of bracing necessary to achieve an excavation depth of 65 feet. Support crane and off-haul excavator alternated trestles as the bracing was installed in six sections (three levels, each with two independent sections.) Upon reaching subgrade, eighty-nine permanent tie downs were installed to resist uplift of the structural mat slab. As the basement was constructed, Condon-Johnson crews worked closely with the General Contractor to remove the internal bracing and allow unimpeded construction of the permanent structure.
Location: San Francisco, CA
Project Partner: Hathaway Dinwiddie
Challenge: Underpinning and tower shoring to preserve existing 100 year old, unreinforced brick walls.
Overview: Condon-Johnson was contracted to provide Micro piles for support of the tower shoring and new construction, installation of soldier piles and lagging to shore up street frontage on Bush and Pine streets, excavate deep underpinning pits for adjacent unreinforced brick structures, and provide tower shoring for two unreinforced brick walls 100 feet long by 50 feet high.
Results: Condon-Johnson was able to manage this project creatively to achieve a safe and successful completion within Hathaway-Dinwiddie’s construction schedule by providing the right people, equipment, and materials on time.
Location: Los Angeles, CA
Project Partner: Skanska-Traylor-Shea, A Joint Venture
Limited access work zones adjacent to live vehicle and pedestrian traffic posed challenges for the installation of the 95 foot 20,000 plus pound soldier pile beams. Drilling through the tar impacted sands at the Fairfax Station resulted in difficulties unique to that specific area of the La Brea Tar Pits. In one area at the Fairfax station, Condon-Johnson routinely cored through 5 levels of existing abandoned bar anchors at every soldier pile location.
Condon-Johnson was contracted by Skanska-Traylor-Shea to perform the soldier pile installation as part of the support of excavation on the Purple Line Extension Project, Section 1. Condon-Johnson installed 1,545 each soldier piles drilling approximately 120,000 feet and hoisting over 23 million pounds of steel for the shoring at the three new stations and tie in. Condon-Johnson began installation at the La Brea station in December 2015, the Fairfax station in August 2016, the La Cienega station in March 2017 and completed the Western tie in shaft in February 2018. Throughout this four mile stretch along Wilshire Boulevard in Los Angeles, Condon-Johnson encountered a variety of challenges from the tar-impacted sand of the La Brea Tar Pits at the Fairfax station to the logistical challenges of heavy civil construction on active and congested city streets.
Condon-Johnson successfully completed the installation of 1,545 each soldier piles, drilling approximately 120,000 feet and hoisting over 23 million pounds of steel safely without any serious injuries or incidents. Condon-Johnson completed its work on schedule avoiding any delay to the project.
Location: Sunol, CA
Project Partner: Dragados-Flatiron-Sukut JV
Challenge: Plan and execute the foundation drilling and grouting scope in a sequence to avoid delay to the critical path earth work activities.
Overview: Condon-Johnson was contracted to complete the foundation drilling and grouting scope downstream of the existing dam to minimize seepage through the underlying bedrock of the future dam. The grout utilized was a suite of cement-based stable high-mobility grouts with varying viscosities. All injection and permeation testing was monitored and recorded via Condon-Johnson’s custom real-time computer monitoring system.
Results: Through collaborative efforts, the design and construction teams, including the General Contractor, were able to work closely to devise an effective plan to minimize the foundation drilling and grouting scope’s duration on the critical path for the new dam construction. Although some procedures were not typical for dam foundation grouting, the performance goals and traditional grouting requirements were consistently met. Four different types of drill rigs were utilized to overcome the challenging access.