Earth, Inc.

The Duquesne Incline, City of Pittsburgh, PA

Earth, Inc. serves as the geotechnical consultant to the Duquesne Incline on Mt. Washington in Pittsburgh, PA. In 1996, the Incline experienced a significant rockfall event. Although the Incline did not incur much damage, its long-term stability was threatened. As a result, Earth, Inc. designed a rockfall remediation system consisting of slope netting and rock bolts on two rock faces of suspect stability on the very steep hillside overlooking downtown Pittsburgh; this work also included shotcrete underpinnings of rock overhangs. The construction work was incorporated into the Port Authority of Allegheny County's contract to perform hillside stabilization along the Conrail railroad shelf.

Following construction, Earth, Inc. designed a geotechnical instrumentation system consisting of 10 tiltmeters attached to exposed rock faces. Continuous remote reading of the tiltmeters including temperature data is received over time at the upper station with automated output being generated to provide baseline data for future comparisons. Alarms have been built into the computerized system to alert Incline personnel if unsual movement has occurred providing a warning of possible impending hillside movement.

Scotia Hollow Road, Allegheny County, PA

As part of the Allegheny County (Pennsylvania) Maintenance Department's Lateral Support Program, Earth, Inc. provided geotechnical engineering services for the evaluation and repair of various landslides, rockfalls, and retaining wall failures involving County roads. For the Scotia Hollow Road landslide project, Earth, Inc. performed a study evaluating numerous site grading, drainage, and structural schemes to control an uphill landslide condition approximately 200 feet in width extending approximately 400 feet uphill before settling upon the development of a cantilevered, soldier beam and lagging fall zone for landslide mitigation.

Interstate 79 in Greene County, PA

Earth, Inc. has provided geotechnical engineering services for the Pennsylvania Department of Transportation, District 12-0 that include the development of an early detection and monitoring system relative to longwall mining beneath Interstate 79 in Greene County. An 8 tiltmeter spread, which was part of a wireless system including solar power sources and radio transmission equipment, allowed for the sending of tiltmeter data to a central location within the tiltmeter spread, thereby providing for real time, cell phone connectivity from the field to the office as well as remote mobile units. As the mining advanced towards the highway, information gathered from tiltmeter data was made available to appropriate District personel to coordinate the enactment of safety measures including continuous on-site observation, traffic alerts, and roadway grade adjustment.

The work also included the development of pre and post mining topographic conditions. Profiles and cross-sections along with 3D survey and presentation of data were analyzed to determine what negative effects mining may have had on slope stability. Prior to the arrival of mining, test borings were drilled along with the installation of inclometers to allow for the monitoring of slope movements at critical locations, some of which included embankments with heights in excess of 100 feet which were originally constructed in areas of prehistoric landsliding.

Interstate 70 in Washington County, PA

An extensive geotechnical laboratory testing program was performed including direct shear testing of coarse aggregates to be used for sliver fill embankment construction with slopes as steep as 1:1. Reccomendations were given for using select materials along with benching of sliver fills for roadway widening. The use of steepened slopes in place of retaining walls along approximately 8,000 feet of roadway resulting in cost savings of over $2,000,000 to the Pennsylvania Department of Transportation.

Pennsylvania Turnpike, Milepost 84, Westmoreland County

The incorporation of a 1,150-foot long geogrid-reinforced embankment with concrete masonry unit facing (segmental block retaining wall) using milled bituminous pavement as structure backfill saved more than $500,000 in construction costs for a 9 mile total reconstruction section of the "original" Pennsylvania Turnpike. This wall is at the top of a very steep (approaching 1:1) existing slope. A soldier beam and lagging type wall was not deemed appropriate because of numerous hard boulders in the underlying material. "Traditional" MSE walls were not expected to provide the economies that the segmental block retaining wall did.

S.R. 0022, Sec. 005 (Water Street Bypass Intersection with S.R. 0453), Huntingdon County, PA

The use of steepened cut slopes at two locations on the order of 100 feet in height with rockfall drop zones at the intersection of S.R. 0022 with S.R. 0453 provided for rockfall mitigation and significant cost savings as part of the 1.8 mile relocation of S.R. 0022 in Huntingdon County. Retaining wall in lieu of steepened slope construction would have resulted in a ten-fold increase in costs for the two areas. Slope flattening was not an option as such excavation would have resulted in the disturbance of a more than 200 year old cemetery at one location and the denuding of over 300 vertical feet of mountainside at the other.