Monthly Archives: May 2015

Geotechnical Contractors

By | News | No Comments

Specialty geotechnical contractor Moretrench  is the first recipient of  the  Innovations in Ground Improvement Award, which was presented during the Colorado School of Mines annual short course on Ground Improvement in Underground Construction and Mining,  held in Golden, CO from May 18th to May 20th, 2015.  According to Course Director Levent Ozdemir, Ph.D., P.E.,  the newly minted award is given for the development of  innovative solutions, products or design to ground improvement in  underground construction or mining.  Moretrench was selected for its work on the Northern Boulevard Crossing in Queens, New York, the 2nd Avenue project in Manhattan, New York, and the Port of Miami Tunnel  project in Florida.

“Each of these projects presented different tunneling challenges,”  notes Moretrench Vice President of Engineering Paul Schmall.  “Northern Boulevard was an SEM tunnel through difficult, complex soils deep below the groundwater table.  2nd Avenue was an unanticipated stretch of mixed faced conditions in a primarily rock tunnel.  And the Port of Miami involved mining of two cross passages between 80 and 120 feet below sea level and situated mostly within a highly pervious coralline rock formation.”

Moretrench Vice President of Engineering Paul Schmall (left) receiving the award from Dr. Levent Odzemir, Director for the Colorado School of Mines short course programs.

Moretrench Vice President of Engineering Paul Schmall (left) receiving the award from Dr. Levent Odzemir, Director for the Colorado School of Mines short course programs.

While ground freezing was used on all three projects, there were markedly different considerations that had to be addressed.   At Northern Boulevard, where the tunnel alignment passed directly beneath an active subway box and an elevated rail track, carefully performed heave and settlement control measures during growth of the freeze and the subsequent thaw period were critical to maintain the integrity of the structures.  Congested above-ground conditions and traffic along 2nd Avenue meant that the work had to be accomplished from two small access areas, using angled drilling and freeze pipe installation.  The Port of Miami cross passages were mined through  a circular frozen zone created by means of horizontally-installed freeze pipes– a first in North America.  Here, the potential for moving groundwater, which hinders freeze closure, was addressed by grouting to reduce the permeability of the coralline formation ahead of Moretrench’s work.  But with the cross passage alignment deep inside the eastbound tunnel, the main components of the ground freezing system had to be located and maintained above ground, almost half a mile from the work zone.  Contact cooling systems were also critical to ensure continuity of the freeze along the entire length of the tunnels.

For further  information on the projects cited in the award, see this recent Tunnel Business Magazine article, and also visit our website Resources ground freezing section for more project case studies.

Overland Bridge Project

By | News | No Comments

Making sure your next project  gets off to the right start is what Moretrench is all about.  No matter the requirement –groundwater control, excavation support, settlement control,  ground improvement, foundation systems – we have the tools, the resources,  and the geotechnical expertise to get the job done.  And for Florida DOT’s Overland Bridge Project,  that expertise came in the form of large-diameter drilled shafts.

The Overland Bridge Project is the largest transportation design-build in the history of Jacksonville, FL. Extending south of the Fuller Warren Bridge that carries I-95 over the St John’s River, the project includes replacement of a series of existing overpasses, widening of both the Fuller Warren Bridge and I-95, and replacement of an existing bridge spanning  Florida East Coast (FEC) railroad tracks.  The $277M project is being accomplished in phases over the next  two  years to allow staged demolition and re-building in order to maintain adequate traffic flow along the I-95 corridor. Moretrench’s Orlando office was the successful bidder for the recently completed Phase 1 drilled shaft bridge foundations,  with further work contracted for Phases 2 and 3.

Art Drill Rig Jacksonville photo (2)

Construction at the Fuller Warren Bridge involves widening of the south end of the bridge to provide an additional south bound lane adjacent to a two-lane exit ramp.  “There were a number of challenges to the shaft installation here,” notes Assistant Branch Manager Kris Stenberg.  “It was a particularly tight site. We were drilling between themain span and the exit ramp. Four shafts had to be installed from a trestle over the river, so we had to ensure that there was no environmental impact to the water during this part of the work.”

The bridge remained open throughout shaft installation. Prior to production work, three sacrificial shafts were constructed at +/- 700-foot intervals in similar soils along the corridor where production shafts were installed, and load tested to verify design assumptions. Twelve,  60-inch diameter land-based shafts and the four, 72-inch over-water shafts were drilled to depths varying between 55 and 80 feet and terminated in competent marl.  All shafts were cased through the upper sands, with stability of the underlying limestone maintained with bentonite slurry.

At the FEC railroad bridge site, two bridge spans remained open. With work accomplished adjacent to active roadways within an urban environment, a heightened level of safety was maintained at all times.  Ten, 60-inch diameter and five, 42-inch diameter shafts were installed to depths of between 55 and 70 feet using the same construction method as the Fuller Warren Bridge shafts.  Moretrench will return to the FEC bridge during Phases 2 and 3 to install a further 21, 60-inch diameter and 6, 42-inch diameter shafts.

Coal Ash

By | News | No Comments

Moretrench is well-known for its dewatering expertise in the civil construction marketplace.  What is not so well known, is that we have been applying that same expertise to the drainage and stabilization of gypsum, a by-product of the phosphate industry, for almost 40 years.  The storage of gypsum is markedly similar to that of another major industrial by-product – Coal Combustion Residual (primarily fly ash and bottom ash).   Both are transported and placed in slurry form, typically in large, above-ground impoundment areas.  And the dewatering methods that have proven so effective for the stabilization of gypsum apply equally effectively to CCRs.

Facility owners are actively working to comply with recent EPA-mandated guidelines on the construction and management  of CCR disposal sites,  and a properly engineered pre-drainage dewatering  program offers several distinct advantages.  For liner placement of active ash ponds, drawing down the groundwater allows stable, near vertical cuts to be made for mass excavation with conventional equipment.  When the intent is to cap the pond, dewatering provides a firm crust on the surface to support construction equipment so that the pond can be graded and the liner placed. Dry ash also occupies  a much smaller temporary storage footprint for liner projects.  Overall, dewatering allows for faster and safer  project completion.

Moretrench’s wide range of services means that we can also offer other critical remediation measures for CCR facilities such as dam and levee repair and rehabilitation, and cut-off and containment barriers to prevent the migration of contaminated soils.

Download our brochure here and see what we can do for you.

Download our brochure here and see what we can do for you.

 

Dewatering

By | News | No Comments

When unanticipated subsurface conditions are encountered on the job site, Moretrench has the in-house resources and expertise  to develop and implement viable alternatives for a wide range of underground construction challenges.  And when this capability is coupled with the ability to respond rapidly when the call comes in, general contractors and owners can look to getting the project back on track quickly and efficiently.  Such was the case for a recent microtunneling project in Camden, NJ.

Jacking pit. The jet grout bottom seal also functioned as a mud mat.

Jacking pit. The jet grout bottom seal also functioned as a mud mat.

The alignment of a  48-inch diameter, 340-foot long utility pipe lay in very close proximity to Newton Creek.  Dewatering to below excavation subgrade is the most straightforward and economical approach to ensuring dry/stable working conditions,  but dewatering was not permitted due to the presence of naturally occurring heavy metals in the groundwater.   Efforts had been made to drive the steel sheet piling excavation support  into the underlying extremely dense (100+ blows per foot) sands sufficiently  below excavation subgrade to minimize groundwater infiltration to quantities that could be handled by sumping.  However, this ultimately proved unsuccessful.  With the project now on the fast track,  the tunneling subcontractor  brought in Moretrench to develop an effective solution that could be implemented quickly.  For this project, the solution that was deemed the best option, based on project objectives and the prevailing site conditions,  was the installation of jet grouted bottom seals.

Continuity of the jet grout was verified by coring.

Continuity of the jet grout was verified by coring.

With time of the essence, mobilization was underway within two weeks of the initial phone call. Working 10-12 hour shifts, six days a week, Moretrench installed 42, 6-ft diameter, 12-ft thick  bottom seals columns within the launch pit excavation support and 43, 6-ft diameter, 8-ft deep columns at the receiving pit.  The contract also included jet grout stabilization of the soils behind the microtunnel break-in and break out portals, and jet grouting  to seal the corners of the steel sheetpiles, which were not interlocked.

During bottom seal installation, similar groundwater concerns arose for the auxiliary transition cofferdams that would be used to bring the 48-inch pipe within the reach of conventional trenching installation. This prompted the owner to add these areas to Moretrench’s scope of work. Despite this additional commitment, and working in  harsh winter weather conditions with temperatures dipping as low as low as 0°F, the entire expanded contract was successfully completed in  two months, allowing excavation to proceed soon thereafter.

Moretrench Southern Region’s 10th Annual Club Zero and Years of Service Banquet

By | News | No Comments

Workers in Moretrench’s Florida-based Southern Region achieving Club Zero or Club Zero Support Team status for the calendar year 2014 were recognized at the February 26, 2015 awards ceremony and lunch banquet held at the Palmetto Club located 15 minutes from the Moretrench Riverview Florida office.

Outstanding individual safety performance is acknowledged by Moretrench when an employee works the entire calendar year with ZERO: accidents; injuries; property damage events; environmental events; or safety violations.  Employees achieving this level of performance are inducted into Moretrench’s Club Zero and Club Zero Support Team recognition programs and receive individual plaques and suitable memorabilia presented individually by Al Schuman, President of Moretrench’s Southeast Division. _BCD7168

There are 116 Club Zero and Club Zero Support Team members for the year 2014 which represents over 60% of the Moretrench workforce.   Included in this number are 28 one year members, 13 two consecutive year members, 28 three consecutive year members, 9 four consecutive year members, 6 five consecutive year members, 6 six consecutive year members, 1 seven consecutive year member, 4 eight consecutive year members, 3 nine consecutive year members and 4 ten consecutive years members.

_BCD7441

In addition to the induction of Club Zero members, employees reaching milestone years of service are recognized.  This year, 10 employees completing 2.5 years of service, 5 employees completing 5 years of service, 18 employees completing 10 years of service and 3 employees completing fifteen years of service were honored.  Employees announcing retirement from Moretrench during the coming year are also recognized for their past service.

This year’s guest speaker was once again Kevin Yarborough, former Assistant Area Director of the Tampa Area OSHA office.  Kevin related his prior safety experiences in his unique, informative, and entertaining style.  Kevin also expressed his admiration for the safety achievements and safety commitment of Moretrench’s employees.

Guests at this year’s event included Moretrench Vice President Greg Ziegler and Safety Director Greg Lewis, as well as representatives from our major clients in the region.  Special guest was Bob Lenz, former Moretrench President and CEO.  Mr. Lenz was presented a special Moretrench Retirement Challenge Coin in recognition of his past hard work and dedication to Moretrench.