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Schmall P.C.,Moretrench
Geotechnical Special Publication | Year: 2017

Groundwater movement can be highly problematic for artificial ground freezing projects, resulting in a freeze with localized unfrozen openings or "windows". Typically, when a frozen shaft is subject to excessive groundwater movement, the frozen cylinder will close to the point where an entrance window will remain on the upgradient side of the shaft and an exit window will remain on the downgradient side of the shaft. The unfrozen openings will typically occur in very coarse soil such as openwork gravel, which is typically very amenable to permeation grouting. While the permeation grouting process has become the customary response, this method has repeatedly proven to be time consuming and costly because the conventional grouts used (such as bentonite/cement or sodium silicate) are susceptible to dilution in flowing groundwater conditions and they do not set as desired when they are injected near frozen ground. In a number of cases, the grouting ultimately rectified the situation but only when applied with a "shotgun" approach, where very large quantities of grout modify the permeability of a very large surrounding area. Several project case histories will be discussed where permeation grouting was used to close the windows. The properties and initial testing of an innovative alternate thermosetting waxy oil grout material will also be discussed. This alternate material is low viscosity, immiscible in water, and can be blended to set at various temperatures based on the injection point proximity to the frozen ground. © ASCE.


Schmall P.C.,Moretrench | Myers J.C.,Moretrench | Spiteri L.P.,Moretrench | Hawkins S.D.,Moretrench
Geotechnical Special Publication | Year: 2017

The Anacostia River Tunnel is one of a series of new CSO tunnels designed to capture sewage overflows that currently feed into Washington, D.C.'s, rivers and divert them to the blue plains advanced wastewater treatment plant. The TBM assembly and main work shaft for the tunnel consists of twin 21.3-m (70-ft) diameter shafts connected by a 30.5-m (100-ft) long tunnel mined by the sequential excavation method (SEM). During the hand mining of the inter-shaft connector tunnel, a ground loss event occurred which resulted in approximately 1900 m3 (2,500 yd3) of material flowing into the tunnel and formation of a sinkhole which encompassed the area between the two shafts. The immediate response included flooding the shaft and tunnel, backfilling of the sinkhole, and an array of exploratory holes to map the limits of disturbance. Jet grouting was selected as the ground improvement method to restore ground conditions in the crown of the SEM tunnel so that mining could resume. Several other ground improvement methods were required to support the jet grouting work, including non-cementitious grout for void filling, compaction grouting to create an interim bulkhead, and jet grouting to create a contiguous improved ground structure and provide a stable face for the subsequent recommencement of tunneling. After six months of remedial work, the connector tunnel was completed and the TBM was launched. This paper describes the design steps and implementation of this complex, challenging and time-sensitive remediation effort. © ASCE.


Sopko J.A.,Moretrench | Khorshidi B.,Construction Inc. | McInnes B.,Construction Inc.
ITA-AITES World Tunnel Congress 2016, WTC 2016 | Year: 2016

The Port Mann Main Water Supply Tunnel involves a 1km long tunnel beneath the Fraser River from Surrey to Coquitlam, BC. At depths of up to 60 m below ground, the earth pressure reached 6 bar. The tunnel is constructed using an EPB TBM and gasketed precast concrete segmental liner. The tunnel and two shafts were constructed in a variety of soil conditions ranging from soft to stiff clays and silts, to compact to very dense sands and gravels. After approximately 800m of mining, a very dense and highly variable soil group consisting of cobbles and boulders halted the TBM. Several options were considered to stabilize the TBM face so an intervention could be conducted. Although de-watering was considered, there was risk of settlement to the Port Mann bridge piers, which was within 500m of the tunnel. Hyperbarics were also considered, however, the cost, schedule and uncertainty of the work that needed to be done, made it a risky option. Ground freezing by Liquid Nitrogen was chosen as the best solution, which would provide a frozen block around the face of the TBM. A temporary platform on the river was designed and constructed to enable drilling and installation of the freezing pipes and temperature monitoring equipment. The operation required close coordination among the tunnelling, marine and freezing sectors. Following the intervention, the TBM successfully broke through the reception shaft, and the remaining project was completed. This paper describes the design, construction and operational approaches used for the freezing and serves as a basis for future projects requiring expedited ground freezing.


Barkauskas B.D.,Moretrench | Splitstone D.E.,Moretrench | Fuller J.A.,HDR | Nemmer J.A.,Trumbull Corporation
Geotechnical and Structural Engineering Congress 2016 - Proceedings of the Joint Geotechnical and Structural Engineering Congress 2016 | Year: 2016

Over several decades, the superstructure of the 100-year-old Butler Street Bridge in Pittsburgh, PA had become severely dilapidated. In addition, the ravine beneath the span had been used as a dump site for ash from the City's Herr's Island incinerator to the point where it was filled almost to the underside of the deck arch. In 2013, the owner, Pennsylvania Department of Transportation District 11-0, began work on a long-Awaited new bridge to entirely replace the existing structure. Each bridge abutment was initially designed to be supported on rock-socketed caissons. The original work plan was to remove the entire bridge superstructure and existing abutments and backfill up to the bottom of the new abutments prior to installation of the caissons. This would necessitate excavation of some 6880 m3 (9,000 yd3) of incinerator ash that was deemed landfill-sensitive. In an effort to reduce excavation quantities and efficiently streamline shoring operations, as well as to alleviate potential foundation element alignment issues that could arise from caisson drilling in the steeply sloping rock, the general contractor sought input from an engineering consultant, which developed an alternative micropile foundation design. This paper discusses the initial design, the re-design and its construction advantages, and installation and testing of the micropile foundation system. © ASCE.


Garlanger J.E.,Ardaman and Associates Inc. | Schmall P.C.,Moretrench
Geotechnical Special Publication | Year: 2012

During routine inspection, staff at a Florida phosphate plant discovered a large sinkhole in a phosphogypsum stack. The owner solicited the services of geotechnical consultant Ardaman & Associates, Inc., to oversee the investigation and remediation. The sinkhole feature was subsequently determined to measure approximately 41 m (135 ft) at its widest point and extend to a total depth of approximately 91 m (300 ft). The occurrence of a sinkhole meant that the underlying confining layer had been breached, permitting low pH water from the stack to flow into the underlying aquifer. The engineering team responded rapidly to alleviate environmental concerns and determined that any groundwater impacts were effectively contained on site via recovery wells, and then implemented a grouting program to remediate the sinkhole and ensure the integrity of the confining layer between the surficial aquifer and the Floridan aquifer. Piezometric water levels confirmed successful remediation of the sinkhole and re-establishment of the confining layer. This paper details the geotechnical investigation and design and implementation of the grouting program, which featured the innovative use of specialized techniques, including sonic drilling, to address technical concerns. © 2012 American Society of Civil Engineers.


Beenenga C.R.,Gannett Fleming Inc. | Myers J.C.,Moretrench | Nokovich A.M.,Pennsylvania American Water Company
Association of State Dam Safety Officials, Dam Safety 2015 | Year: 2015

In the spring of 2011, remediation efforts were undertaken to address operational and regulatory issues at Nesbitt Dam. Planned construction activities included excavation at the toe of the dam and installation of toe drain piping and blanket drainage as well as stabilization of the non-overflow, spillway and embankment sections of the dam for overtopping protection. During construction, in early 2012, a depression of approximately15 ft (4.6 m) in diameter was observed on the upstream slope of the earth embankment portion of the structure. This paper will discuss the treatment actions and steps taken to protect dam stability, including analysis of the situation, development of the preliminary work plan, and the remediation program performed by a specialty geotechnical contractor. Highlights of the emergency actions included commencement of work operations while diagnoses were ongoing. Observations and data were continuously gathered during the treatment and remediation process. This required daily cooperation, coordination, and conference call discussions among project team members, i.e., owner, design consultant, regulator, and contractor.


LaRue K.,Moretrench
Geotechnical Special Publication | Year: 2010

A permanent soil nail wall was constructed to support an existing bridge abutment of an active major interstate. During the construction of the wall, poorly graded sand with trace silt (SP) was encountered directly beneath the abutment footing. The soil did not posses sufficient "face stability" to permit soil nail wall construction to proceed as originally designed. Further investigations determined this soil condition to be present the full depth of the proposed excavation support system thus requiring an alternate solution to be implemented. Due to restrictions associated with future roadway construction, sodium silicate based chemical grouting of the excavation face along the full height of support was selected to temporarily stabilize the poorly graded sands and permit the originally designed soil nail wall to be constructed. This paper discusses the conceptual design and construction procedures utilized to carry out the grouting program and soil nail wall construction. © ASCE 2010.


Sopko J.,Moretrench | Chamberland R.,Moretrench
Tunnels and Tunnelling International | Year: 2015

Aguas del Parana UTE (ADP), the prime contractor joint venture for the SiStema de Potabilizacion Area Norte project, flooded the shaft and attempted to seal the leaking joints with a grouting program, initially by direct injection of the grout using tremie methods to address the challenge of leaking joints, which hampered the progress of the project. Ground freezing offered several immediate solutions to the problems associated with leaking slurry wall panels and bottom instability following the excavation. A frozen soil cofferdam around the perimeter of the distressed slurry wall would conform to the shape of the panels and seal any of the leaks by freezing the water in the joints. The freeze pipes could also penetrate below the base of the slurry wall into the impermeable clay and provide bottom stability of the excavation.


Sopko J.,Moretrench | Chamberland R.R.,Moretrench
Tunnels and Tunnelling International | Year: 2014

The application of the Michigan State University research to the project in Milwaukee, including the recent Harbor Siphons Tunnel permitted the construction of frozen earth structures at locations that otherwise could not be completed due to project site constraints.


Sopko J.,Moretrench | Chamberland R.R.,Moretrench
Tunnels and Tunnelling International | Year: 2014

The article describes the top heading and bench excavation method for the Waneta Expansion Project, and the challenges and benefits of using a self-advancing tunnel form on a 17 per cent slope. The WANETA Expansion Project (WAX) is located near the existing Waneta Dam site at the confluence of the Pend d'Oreille and Columbia Rivers approximately 10km south of Trail, British Columbia. The WAX owners consist of a partnership between Fortis, Columbia Basin Trust and the Columbia Power Corporation. The access adit was 6m wide by 6m tall, modified horseshoe in shape, and 135m long with a grade of -12 per cent. Developing the access adit allowed RFK to excavate the penstock tunnels and remain off of the surface works critical path and out of the way of other site excavations. The access adit had low cover and would be used as primary ingress/egress during the tunnel excavation and the concrete liner phase.

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