Friday, April 20, 2018
Hoover Dam Bypass
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Hoover Dam Bypass (under construction)
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Reconstruction of Six Bridges over NYCT, LIRR and BQE
Project Location:
Brooklyn, NY

Converse Responsibilities:
Geotechnical Investigation

The New York City Department of Transportation (NYCDOT) planned to rehabilitate or replace portions of six existing bridges in Brooklyn, New York to conform to established design criteria:

§  Congress Street Bridge over BQE: Removal of existing two-span superstructure and replacement with a new two-span structure consisting of composite reinforced New York - Reconstruction of Six Bridgesconcrete deck and steel stringer system.
§  Lincoln Road Bridge over BQE: Removal of existing four span structure and replacement with a single span steel bridge with integral abutments built behind the existing abutments.
§  Seeley Street Bridge over Prospect Avenue: Rehabilitation of the existing single span arch bridge.
§  East 3rd over LIRR: Replacement of existing single span, concrete-encased, steel stringer bridge with a new steel structure.
§  52nd Street Bridge over LIRR: Removal of existing two-span, simply-supported, concrete-encased, steel stringer bridge and replacement with a new steel stringer single span.
§  19th Avenue Bridge over NYCT: Replacement of four-span monolithic rigid reinforced concrete frame arch structure with new steel stringers and a concrete deck.

Converse performed field and laboratory geotechnical investigations to evaluate the subsurface conditions and the proposed design alternatives. Included in the geotechnical study report were the design parameters for evaluating the safety against sliding and overturning for both static and dynamic loading conditions of the bridge foundation substructures. The work included drilling, laboratory testing, integral abutment design, criteria for transverse loading, foundation design and seismic evaluation and design.

Pacific Canyon Railroad Bridge
Project Location:
Eureka County, Nevada

Converse Responsibilities:
Geotechnical Observation and Testing

The project was located southeast of Palisade, Nevada, where the westbound railroad tracks cross the Humboldt River before entering a tunnel. A westbound freight train had derailed and damaged the approximately 100-year-old bridge at this location. The railroad had replaced the damaged bridge with a new 7 span precast concrete trestle supported on HP14 x 89 pile bents. The pile load was about 112 tons. Converse performed a limited geotechnical investigation to gather information for the design of the new bridge, specifically whether the new piles could be driven or if drilling and socketing techniques would be required.Union Pacific - LV
Replacement Bridge on South Fork Road

Project Location:
Lytle Creek, CA

Converse Responsibilities:
Geotechnical Investigation

The project consisted of a proposed replacement bridge to be constructed along South Fork Road about 180 feet west of Lytle Creek Road. The Replacement Bridge on South Fork Roadsite was approximately six miles northwest of Interstate Highway 15. The replacement bridge was proposed to be a pre-fabricated steel and concrete deck bridge approximately 26 feet wide and 38 feet long with grouted rock upstream and downstream.

Converse provided a geotechnical investigation, including a site reconnaissance, subsurface field exploration, laboratory testing of representative site soils and preparation of a geotechnical report with recommendations for design.
City of Pasadena Street Improvements
Project Location:
Pasadena, CA

Converse Responsibilities:
Geotechnical Observation, Materials Testing and Inspection

Converse provided on-call geotechnical engineering and materials testing services for the City of Pasadena’s street rehabilitation and reconstruction program from 2005 to 2010. Converse services included on-call geotechnical observation and field density testing, asphalt compaction testing, sampling and testing of concrete, continuous shop inspection and field inspection of welding and part-time field density testing during post-grading and utility trench backfill. Work was performed at the following locations:
  • Altadena Street
  • Arroyo Parkway
  • Arroyo Seco Creek BridgePasadena Streets
  • Avenue 64-Street Resurfacing
  • Del Mar Avenue
  • Fair Oaks Boulevard
  • Grant Park
  • La Pintoresca Park
  • Nina Street
  • Walnut Street & Altadena Drive
  • Washington Park Shelter


Pavement construction can be a significant cost for many projects. If the pavement is not designed correctly, it may require extensive maintenance or rehabilitation that can result in ongoing costs.

Converse’s engineering team is experienced in the design of asphalt concrete and Portland cement concrete pavement systems, as well as specialty systems such as pervious pavement and stone pavers.

Pavement structural sections are recommended based on the resistance, known as R-value, of the underlying soil and the intended traffic index, which describes the amount of load that the pavement must support. The engineer evaluates these factors and provides the recommended thickness and type of aggregate base and concrete. Depending on the site conditions and project requirements, several options may be feasible.


Underground pipelines are affected by their surrounding soils. When providing recommendations for a pipeline, geotechnical engineers consider the potential for settlement, liquefaction, or corrosion by the soil. They provide recommendations for pipeline design based on these and other factors.

Pipelines are supported and covered by earth materials. Proper selection and placement of the materials around the pipe is essential. Geotechnical recommendations are required for the material placed in the pipe bedding, pipe zone, trench backfill and the techniques used to place and compact each material.

Retaining Walls

Retaining walls may be used to support steep slopes when the earth materials lack adequate strength, or when there is not enough space for a slope. In order for a retaining wall to be stable, its design must include all of the loads that it will support. Converse’s engineers have provided geotechnical recommendations and parameters for the design of numerous types of retaining walls.

Cantilever retaining walls are usually constructed of concrete and include a large footing at the base of the wall. The space behind the wall is backfilled with compacted fill soil. Important considerations are the pressure exerted by the retained soil, the weight of the backfill, drainage behind the wall and compaction of the backfill.

Mechanically stabilized earth walls typically consist of interlocking masonry blocks with layers of synthetic geo-grid extending behind the wall into compacted fill. Drainage is not generally an issue, but the geo-grid material and spacing must be designed based on the correct loads and soil characteristics.

Soil nail and rock bolt walls use steel rods to stabilize a soil or rock slope. Depending on the geologic conditions and wall design, the rods may be held in place by friction, epoxy, or mechanical anchors. The exposed end of the soil nails or rock bolts may be treated cosmetically or a structural concrete facing may be required to retain the earth material at the slope face. The success of this type of wall depends on accurate characterization of the materials in the existing slope and appropriate geotechnical recommendations for the size, strength, spacing and placement of the soil nails or rock bolts.



Buildings and other structures may be supported on the ground by several different types of foundations. Shallow foundations include the spread footings used around the perimeter of most buildings as well as the thicker and more rigid mat foundations used in certain difficult soil conditions. Deep foundations include cast-in-place-drilled piles, driven piles and micropiles.

Engineers evaluate the site geology and project requirements and provide recommendations regarding which type of foundation are appropriate. They also provide essential information for the design and construction of the foundations. Depending on the project, these parameters might include how much load the ground will support, how far footings should extend into the ground, sizing for deep piles, or how far apart piles should be placed.



Most project sites are graded before construction of the improvements. The grading may transform the layout of the site, or it may return the site to something close to its original appearance. In either case, Converse’s engineers provide recommendations for site grading that will provide a stable surface with enough strength and stability to support whatever structures are planned.

The natural soil found at the surface of many sites is too soft to support buildings or other improvements. Remedial grading may be recommended to remove several feet or many feet of unsuitable earth materials. In many cases, the removed soil may be re-used as compacted fill. Occasionally, site conditions prevent the recommended remedial grading, so specialized ground improvement techniques, such as vibrocompaction, stone columns, or surcharging, are utilized.

Compacted fill is soil that has been moistened and compressed to a specified density. This process reduces the potential for the fill soil to settle or erode. Engineers provide specifications for how much compacted fill should be placed under buildings or other improvements and how the fill should be compacted.

Slopes may be constructed of compacted fill or cut into existing natural earth materials. Both fill slopes and cut slopes must be stable and resistant to erosion. Converse’s engineers and geologists evaluate slopes in design and in the field and provide recommendations to improve stability where needed.

Geotechnical Engineering

Geotechnical engineers analyze the properties of earth materials at a project site and evaluate whether those materials meet the project requirements. They provide recommendations for how structures should be designed based on the underlying soils or rock. They also recommend earthwork to improve the ground conditions to meet the needs of the planned structures. Converse’s engineering team routinely provides geotechnical recommendations for building foundations, pipelines, bridges, tunnels, pavement and other structures.

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