What were the geotechnical challenges of working on the One South Market project?

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One South Market site during construction

One South Market is one of the latest high-rise buildings to fill the skyline of downtown San Jose in the last few years. In the past, the City of San Jose has encountered difficulty attracting developers to bring new tall building projects into downtown.  Due to downtown’s close proximity to the aircraft flight path to Mineta San Jose International Airport, the San Jose 2040 General Plan states that all new tall building heights be subject to maximum building height limitations as mandated by Federal Aviation Administration regulations.

In order to make the project economically feasible with the building height limitations, the developer of One South Market conceived a plan that included a 23-story tower of luxury condominiums and a six-story parking structure located next to the tower.  The tower was constructed at-grade, while the parking structure was constructed with a three-level basement.  Langan worked with the design team to evaluate the settlement compatibility between the two buildings and optimize the foundation system to support both structures.

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One South Market

Challenges for this project included installation of temporary shoring to support the 38-foot excavation for the parking structure. The temporary shoring protected surrounding buildings and city streets and allowed for management of the dewatering of the shallow groundwater during construction. The temporary shoring consisted of soldier-pile and lagging with tieback anchors; however internal steel beam walers and rakers were used for a nearby historic building. Installation of soldier piles included vibrated-in piles and drilled piles near existing structures to reduce vibration impacts.

It was very rewarding to be part of this project team, assist with the design and building’s LEED silver certification and to be a part of the future growth of downtown San Jose.

 

Answer provided by Gabriel Alcantar, PE, Project Engineer
Gabe is experienced in performing geotechnical evaluations and managing construction projects throughout the San Francisco Bay Area.  As a project engineer, he works on projects involving shoring systems, mass grading, installation of deep and shallow foundational systems, and  ground improvement. Additionally, he performs probabilistic hazard seismic analyses for projects within California and internationally.

What were some of the challenges and rewards associated with working in the Golden Gate National Recreation Area and specifically the Presidio of San Francisco?

The most rewarding aspect of working within the Golden Gate National Recreation Area (GGNRA), and specifically the Presidio, is being part of a team that transformed a former US Army base into a spectacular National Park.

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Battery East – Before

Our role as the environmental consultant began more than 16 years ago. At that time, the US Army base at the Presidio had recently transferred to the National Park Service with the Presidio Trust in charge of managing the interior park lands. The National Park Service  would control coastal lands.

Some of our projects included assessing and achieving clean closure at landfills on or near the coast of the Presidio, cleaning up soil impacted with lead near the Golden Gate Bridge, assessing water quality in habitat ponds to support the resurgence of the red-legged frog, and performing remediation on former landfills to assist in bicycle and pedestrian trail development.

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Battery East – After

Our biggest challenge was navigating the complex regulatory structure associated with working within the park to clean-up previously contaminated sites and obtain closure. Some of the government agencies with jurisdiction in the GGNRA are the Regional Water Quality Control Board, Department of Toxic Substance Control, Golden Gate Bridge Highway and Transportation District, National Park Service, and Presidio Trust. Another critical component to successfully manage a park project is to understand land use and applicable cleanup standards, whether they be commercial, ecological, recreation, or residential. Different areas of the park have different cleanup criteria, which are based on land use, exposure assumptions, and background conditions.

The GGNRA now consists of over 80,000 acres of ecologically and historically significant landscapes in the greater San Francisco Bay Area.  Over 14 million people visit and enjoy the GGNRA each year making it one of the largest urban parks in the world. We at Langan are proud to have helped open many areas to the public.

About Joshua Graber, CHMM
Joshua is a senior project manager with nearly 20 years of environmental consulting experience.  His responsibilities include geologic, hydrogeologic, and chemical analytical evaluations; Superfund site management; vapor intrusion assessments and mitigation; soil and groundwater remediation; litigation support; remedial excavation, waste classification, and disposal; and technical report preparation. He currently manages the Presidio-wide groundwater monitoring program, GGNRA projects, in addition to other projects in Northern California.

Q&A: Langan designs foundations for some of the tallest towers around the world. How does the firm provide its expertise in so many locations?

Kingdom Tower, Jeddah, KSA

Kingdom Tower, Jeddah, KSA

Langan’s core values of technical excellence, practical experience, and client responsiveness are desirable qualities that export well around the world. The technical excellence starts with a roster of geotechnical engineers that are trained at world class universities. This deep knowledge of soil mechanics, engineering geology, and foundation design allows us to apply fundamental and advanced engineering principles in any type of geology.

As for practical experience, it is essential when adapting to local construction equipment, workmanship, and materials. Many times, foundation options available in North America are not economically feasible in emerging economies.  We find that labor is less expensive compared to construction materials, where the opposite is often true in the U.S.

Last is client responsiveness. We find, especially in emerging markets, that few design teams can outpace Western project teams from concept design all the way through contract documents. Our international clients welcome this accelerated pace of work, because no matter where you are, time is money.

About Alan Poeppel, PE
Alan has over 20 years of diversified experience in geotechnical engineering projects involving the management, investigation, instrumentation, design, and construction of projects in the United States and overseas. He has spearheaded  a number of high-rise “super” towers projects in India and the Middle East including Kuala Lumpur City Center and the 1,000-meter-tall super structure, Kingdom Tower, in Saudi Arabia.

Q&A: What are the unique engineering challenges for the Sutter Health CPMC project on Cathedral Hill?

CPMC Van Ness and Geary, located in the bottom left of the image, is on Cathedral Hill in San Francisco, CA

CPMC Van Ness and Geary (bottom left of the image) is on Cathedral Hill in San Francisco, CA.

The Sutter Health CPMC Van Ness and Geary Campus is highly visible: it is located in the heart of city, considered to be a future flagship medical center, and involves demolitions, deep excavations, and constructing an underground tunnel. This year, our geotechnical and environmental engineers focused heavily on the hospital excavation and the tunnel construction underneath one of San Francisco’s most congested and centrally located roadways, U.S. Highway 101/ Van Ness Avenue.

Closing down the road for the initial stage of the tunnel construction was the foremost challenge, but it was a necessary component. Earlier this year, the development team obtained the City and County of San Francisco’s approval and coordinated extensively with Caltrans to close down Van Ness between Geary and Post for three 72-hour periods, from Friday at 12:01 a.m. to Sunday at 11:59 p.m. The first two closures were completed last spring and the final closure will occur later this year.

During the first two closure periods, our field staff worked around-the-clock in rotating eight-hour shifts to help ensure that every necessary task was completed within the allotted time frame. Soldier beams were installed on either side of the tunnel to provide temporary excavation support and also to support temporary, traffic-rated decking atop them. During the first two closure periods, the construction team installed all soldier piles and completed an excavation of about 5 feet below Van Ness Avenue. As the excavation progressed, timber lagging boards were installed between the soldier piles. The tunnel excavation work then moved to the hospital side, where hand-digging equipment is being used to complete the tunnel, which will bottom approximately 25 feet below Van Ness Avenue.

Construction on the CPMC Van Ness and Geary site in San Francisco, CA

Construction on the CPMC Van Ness and Geary site in San Francisco, CA

The entire project team, including architects, engineers, contractors, and subcontractors, has also been dedicated to sustainability. For example, an estimated 51,000 tons of concrete and 5,000 tons of steel were recycled from the hotel demolition. The team is aiming for LEED Silver certification for this project, which will make Sutter Health CPMC Van Ness and Geary one of the largest LEED-certified hospital campuses in the world and only the fourth LEED-certified hospital in California.

Bringing this extraordinary project to fruition has required close coordination, efficient project integration, and creative problem solving. Our focus has been highly responsive and we have completed tasks on, or ahead of, schedule. We are eager to see this project come to life and serve the community.

Answer provided by Cary E. Ronan, PE, GE
Cary has over 18 years of experience performing and managing geotechnical investigations and construction observation services for numerous projects throughout the San Francisco Bay Area. She provides project management and supervision services during investigations for commercial, retail, and residential developments, including high-rise developments as well as healthcare, school, university, and museum facilities.

Cary directs subsurface investigations, designs and evaluates foundations systems, performs engineering analyses, and directs field and office personnel. She has performed engineering analyses to determine settlement behavior of soil under loading, bearing capacity for shallow foundations, lateral and vertical capacity for deep foundations, and evaluated slope stability and seismic hazards including liquefaction potential.

Photography: ©2015 Brian Haux – SkyHawk Photography

Q&A: What were the challenges of the Crescent City Harbor Rehabilitation Project?

Crescent City Inner Harbor

Floating docks and piles were replaced with stronger concrete versions.

A little background information

Four years ago the Crescent City Harbor, named for the crescent shaped beach south of the city, was destroyed by devastating tsunami waves generated from an 8.9 magnitude earthquake in Japan. Langan provided geotechnical engineering services during design, contractor selection, and construction for the rehabilitation of the harbor. The harbor previously consisted of floating docks, which served as slips for commercial and recreational boats, supported by concrete piles with relatively little embedment into the weak bedrock. Most of the concrete piles were sheared off by the forces generated by the tsunami waves. The project included replacing the old piles with piles designed to resist future tsunamis, stabilization of the harbor slopes, and other onshore improvements.

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New foundations were constructed for the three gangway landings.

Challenges

Langan was a critical part of the project team, working closely with Ben C. Gerwick and Strover Engineering, from 2011 to 2014.  The challenges of this project included designing the facility to resist future tsunamis, shallow highly-fractured bedrock, and high seismicity and potential for strong ground shaking.

Langan’s geotechnical engineering services included developing lateral pile response analyses (L-Pile) to aid in the design of the floating boat docks, providing recommendations and design criteria for the foundations of the gangway landings, and reviewing contractor value engineering, testing, and installation logs. The lateral capacity of the piles included kinematic forces due to a design level tsunami.  In addition to foundation design, we also evaluated the stability of harbor slopes for both static and seismic conditions, and provided recommendations for increasing their stability. We used historical design documents and boring longs, as well as the result of our exploration on land and water.

Crescent City Inner Harbor

A barge-mounted drill rig was used to advance the borings over water.


Today, Crescent City Harbor is completely restored and fully operational. Overall, Langan’s engineering design services were a critical part of assisting the Harbor District in achieving their goal to recreate the harbor better than it was, with the ability to withstand future natural disasters.

 

Answer provided by Haze Rodgers, PE, GE
Haze has over twelve years of professional experience managing, developing, and performing geotechnical studies including explorations, analyses, and construction observation services for various projects throughout California, specializing in offshore design.

Q&A: What were the technical challenges of the Park ‘N Fly project?

We asked our site/civil project manager, Katherine Regina:

What were the technical challenges of the Park ‘N Fly project?

Langan has been involved with the project since 2011, when the site was a vacant lot adjacent to Park ‘N Fly’s existing facility. Initially, we provided site/civil, geotechnical and environmental engineering services directly to the owner. When Park ‘N Fly leased the site in 2013, Langan remained on as the lead engineering consultant. Since Park ‘N Fly is based in Atlanta, GA, we added our  project management services and served as the owners representative during the complex permitting and approval process, as well as during construction and project close-out.

Katherine Regina

Katherine Regina, Project Manager

The greatest technical challenges of this project included raising the site above flood elevations and designing for future settlement (as the site is over Bay Mud), implementing stormwater quality improvements, and coordinating the design team, which included architects, structural and mechanical engineers, landscape architects and contractors. We obtained the requisite approvals from the City’s Planning Commission, Design Review Board, Building Division, and Engineering departments. The design and approval process also involved a new deceleration lane on Produce Avenue and the relocation of PG&E gas mains, regulators and electric infrastructure. The project was a C.3 regulated project and was required to meet San Mateo Countywide Water Pollution Prevention Program guidelines by treating runoff for the entire site. This was a challenge due to the high ground water table, on-going flooding issues on and off-site, and shallow existing stormwater infrastructure that had tidal influence. The project implemented state-of-the-art linear bio-retention systems that were designed to capture and treat the required runoff volume as well as detain large storm events during high tide. Finally, our team was involved throughout the construction phase of the project and provided observation and testing services including foundation and utility installations.

Park 'N Fly

Park ‘N Fly, San Francisco International Airport

Overall, Langan’s project management and engineering design services were a critical part of assisting Park ‘N Fly in achieving their goal to expand parking and create an easier way for travelers to park at San Francisco International Airport.