Monthly Archives: April 2015

Around Moretrench: Wallace Hayward Baker Award Highlights a History of Innovation

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When Vice President of Engineering Paul Schmall, Ph.D., P.E., received the 2015 Wallace Hayward Baker Award in March for “ingenious innovation in the field of ground modification…resourceful development of a new technology or the creative application of existing technology…”, the occasion was more than a great source of pride for the Moretrench family.  It also served to remind us that innovation is deeply rooted in the company culture.

Paul would be one of the first to say that finding new and better ways to resolve construction challenges is ‘in the blood’ at Moretrench.  Indeed, a landmark invention is the reason that Moretrench as we know it exists. That invention was the first practical wellpoint and  came about  in 1924 when company founder Thomas Moore, then head of a trenching machine company, was faced with a dilemma.  A trenching contractor that he had leased a machine to had encountered Bull’s Liver silts that effectively slowed pipe laying to almost a standstill.  Moore took over the contract and set to work experimenting in his kitchen sink until he had a wellpoint that worked in these difficult soils. His wellpoint revolutionized the dewatering  industry and changed the direction of the company.

Paul Schmall, receiving the Wallace Hayward Baker Award from Allen Cadden, President of the Geo-Institute of ASCE

Paul Schmall, receiving the Wallace Hayward Baker Award from Allen Cadden, President of the Geo-Institute of ASCE

Innovation and resourcefulness continued to punctuate the Moretrench timeline. In the 1950s, steel sheeting was specified for water cut-off through  a stratum of openwork gravel to allow dewatering of the excavation for the Kammer Power Plant.  But steel sheeting was in short supply and the project was on the fast track. Over a million gallons of bentonite-cement grout developed in the Moretrench laboratory successfully sealed the gravel, in what was thought to be the first extensive use for such a purpose.  Excavation for the Humble Oil Building in Houston was accomplished with a specially designed ejector system,  one of the first uses of ejectors for construction dewatering.  And an early company  belief in ground freezing for the urban construction environment was instrumental in bringing a European concept to the attention of the wider American marketplace.

Today, ground freezing  is used for many different applications, particularly in the tunneling industry, and Moretrench is in the forefront.  For Boston’s Big Dig, Moretrench used mass freezing to allow jacking of massive box tunnels. This remains the single largest ground freezing project ever undertaken in the United States.  More recently, at the East Side Access Northern Boulevard Crossing in Queens, NY, horizontal ground freezing, compensation grouting, and provision for soil extraction below the water table – another Moretrench first  –  were critical components.

“Paul’s award underscores what Moretrench is all about,” notes President and CEO Art Corwin, P.E. “We have always thrived on finding a better way to accomplish the job. And we’re not done yet. Not by a long way.

Ground Freezing Expertise

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Although ground freezing had been widely used in Europe since the late 19th century for the sinking of deep mine shafts, the technique was largely ignored in the United States.  In fact, only two projects were completed between 1888 and 1954.  A major drawback was the high cost and construction time of the hangar-sized freeze plants required, limiting the use of freezing to long-term projects on open sites.  But with the advent of mobile freeze plants  in the 1970s, Moretrench was quick to recognize the potential in the urban marketplace and established a ground freezing division in 1976.  Industry acceptance was initially slow, but from small beginnings ground freezing has grown to be a core technology, with a number of notable complex and challenging projects to the company’s credit on major water systems and tunneling projects in North America.   Recently Moretrench was called in to go further afield to Argentina, where a particularly persistent issue had effectively halted the completion of an access shaft  for the Sistema de Potabilización Area Norte that will transport and treat raw water from the Paraná River, providing potable water for 2.5 million residents in Northern Buenos Aires province.


The project’s Access Shaft #3 had experienced persistent soil and groundwater ingress through the earth support slurry wall panels during excavation, which several remedial efforts over time, including dewatering and various grouting programs, had failed to resolve.  The shaft was eventually backfilled with concrete to above the tunnel crown to allow tunneling to proceed.  Moretrench was contracted to design and furnish  a ground freezing system that would provide a watertight barrier and allow the general contractor to complete the shaft.  Moretrench also provided on-site supervision  during system operation, and monitoring  through to final liner installation.

All ground freezing equipment, including pipes, fittings, tanks, instrumentation and data acquisition system, and two mobile freeze plants with a combined refrigeration capacity of 281 tons, was shipped from Moretrench’s New Jersey headquarters. The installed system consisted of 48 vertical freeze pipes around the shaft perimeter, 25 angled freeze pipes installed around and beneath the tunnel, and seven temperature monitoring pipes. After nine weeks of freezing, closure was verified by temperature and piezometer data, allowing the prime contractor to install the base slab reinforcement and the final concrete liner. The shaft remained dry and stable throughout.

For a comprehensive discussion of this challenging project, see Argentine Shaft Saviour by Moretrench Director of Ground Freezing,  Joseph A. Sopko, Ph.D., P.E.



AROUND MORETRENCH: Moles Students Day Takes to the Water

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Since 1962, Students Day has been an annual event of the Moles, an organization of the heavy construction industry.  Each year, participating engineering students  and faculty  members tour a major construction site and learn about key aspects of the work from experts  with participating firms.  The event  is developed under the guidance of the Moles Education Committee, currently chaired by Moretrench Vice President of Engineering Paul Schmall, Ph.D., P.E.,  and stems from the organization’s continuing  commitment to developing and  supporting future engineers and construction professionals.    TZC041015p157lr

This year, the day-long event, held on April 10th was focused on the  new Tappan Zee Bridge, a 3.1-mile long, twin span cable stayed structure.  Scheduled for completion in 2018 at a cost of $3.14 billion, this is the single largest bridge construction project in the history of New York City and is being built under  the management of Tappan Zee Constructors, LLC (TZC), a  design-build joint venture of  Fluor Enterprises, Inc., American Bridge Company, Granite Construction Northeast, Inc., and Traylor Bros., Inc.

To best see the work in progress, the 350 students and faculty, drawn from 20 colleges and universities, boarded the 165-foot cruise boat ‘The Brooklyn’  and viewed  the construction at eye level from the water.  The day began with a welcome  from Walter Reichert of TZC, which hosted the event, and a presentation from Robert Palermo of  GZA Geoenvironmental Inc.  Points of interest on the tour included the main span piles and pile caps, as well as the armada of cranes and barges performing the work.   The group also had the opportunity to see one of the world’s  largest floating cranes in action.  Dubbed the “I Lift NY,” the massive crane has a 328-foot boom and will be used to install large sections of the bridge, some of which weigh 1,000 tons.

Along with Moretrench, major construction firms with volunteers for the day’s activities included  Kiewit, E.E. Cruz, Railroad, Weeks Marine, Ferreira, Schiavone, and Yonkers.



Moretrench and the Moles

Moles members are leaders in their profession who are dedicated to promoting the industry and supporting their colleagues through outreach programs, networking opportunities, and student scholarships.   Moretrench  has long been actively involved with the organization, with staff members serving  on various committees.  Company President & CEO Art Corwin, P.E. has served as Moles President, as has former Moretrench President John Donohoe, P.E.    Both Donohoe and another former Moretrench President, Robert Lenz, P.E.,  were recipients of the Moles Member Award for Outstanding Achievement in Construction.  To learn more about the work of the organization, please visit

Butler Street Bridge Project

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Original 1914 bridge.

As a full-service geotechnical contractor, Moretrench has the capability of providing turnkey solutions that address more than one construction challenge on a single site. This is highly advantageous to owners, general contractors and construction managers in terms of overall scheduling and streamlining the components of the project.  The wide range of tools at our disposal also allows us to respond rapidly with field-engineered solutions should an unanticipated subsurface issue arise during the course of the work.

Officially opened in October, 2014, the Butler Street Bridge replacement has been a long time coming.  The original reinforced concrete spandrel deck arch, completed in 1914, had deteriorated badly over the years, and the ravine it crossed had been filled to the underside of the span with incinerator ash.

Completed replacement structure

Caisson foundations were originally specified for the re-build, with Moretrench awarded the contract for the work.  However, caisson installation would involve excavation of 9,000 CY of ash, deemed landfill-sensitive,  as well as complete abutment removal. The general contractor, Trumbull Corporation, therefore sought an alternative  approach from its engineering consultant that would minimize excavation volume and abutment demolition.  This resulted in a micropile foundation system being accepted by PennDOT.  Since micropiles are also a Moretrench specialty, the transition to this method was accomplished seamlessly, with minimal delay.  Moretrench was also subsequently awarded the contract for beam-and-lagging support of excavation.

A primary challenge during production work was that 18 of the micropiles had to be drilled through up to 15 feet of the remaining heavily reinforced bridge arch structure as well as the abutment foundations.  With the installed locations critical to the overall design, Moretrench developed multiple alternative drilling approaches to ensure that deviation from the design location did not exceed the maximum six inches specified.  Crews worked around the clock in typical Pittsburgh winter weather conditions to successfully complete  the foundation work within the tight schedule.

See the full article from the February/March issue of Foundation Drilling magazine here.