The American Council of Engineering Companies of Pennsylvania (ACEC/PA) recently honored engineering firms from across the commonwealth at the organization’s annual Diamond Awards for Engineering Excellence. The highest honor, the Grand Conceptor Award, was presented to WSP USA Inc. for the Forbes Road Emergency Slide Repairs project.

“Accomplished engineering firms from across the commonwealth submitted entries for design, safety, and engineering projects aimed at building better, stronger communities," said Roseline Bougher, President of ACEC/PA's board of directors. "The selection process was difficult, but we believe these awards and special honors represent the very best of Pennsylvania's engineering consulting industry. We take great pride in watching our member firms bring these critical projects to fruition, often in the face of tough obstacles along the way. It has been so exciting to see these firms push themselves to achieve such fantastic results for their clients and truly work to create a better Pennsylvania.”

The Forbes Road Emergency Slide Repairs project consists of slide repairs for SR 2102 Section A02 (Forbes Road) and the adjacent slopes above Turtle Creek in Trafford Borough, Allegheny County, Pennsylvania. Western Pennsylvania has witnessed a dramatic increase in the number of landslides over recent years, and in February 2019 multiple landslides occurred in the project area, making the road unsafe for the traveling public.

“Not only was it dangerous for the traveling public, but there was also going to be impacts to utilities for people in the corridor,” said John Nicholson, Vice President, Pittsburgh Business Leader at WSP. “PennDOT realized that and authorized immediate remediation and repair of the roadway to protect public welfare and safety.”

Forbes Road is the most used and efficient transportation link in the area and is also heavily traveled by commercial traffic. To reopen the road as quickly as possible, the Pennsylvania Department of Transportation (PennDOT) called upon WSP to develop an emergency design to repair the dangerous slide.

WSP’s team mobilized quickly to investigate the area, which resulted in the discovery of extremely high levels of PCB contamination, volatile organic compounds, and heavy metals in the soil. The initial $18 million design concept involved over-excavating, disposing of the hazardous excavated material, armoring the slope with rip-rap, and completing the roadway reconstruction. However, the high hazardous material disposal costs far exceeded PennDOT’s construction budget.

The WSP team engaged in multiple brainstorming sessions to develop a cost effective and safe repair that minimized waste disposal requirements. The solution to this challenge was to drive H-piles near the stream edge and backfill with appropriately sized R-rock, reducing the project cost to just $1.6 million. This was the first use in the region of H-piles driven specifically with length exposed to contain rock slope reinforcement in this manner.

“PennDOT first allowing collaboration and brainstorming to come up with a creative solution to this project was key,” Nicholson said. “When they got the first cost estimate regarding remediating all of the bad soil and contaminated soil, they didn't panic and we put our heads together. They really allowed the design team to come up with a solution to the problem. ... Ultimately the solution that we came up with saved them millions of dollars. I think the client was extremely happy with that.”

The entire project included H-pile construction, slope repair, drainage repair, full-depth shoulder reconstruction, milling and resurfacing, excavation, embankment, and guiderail replacement. The work was completed on budget and on an emergency timeline, with the entire project from emergency declaration to project completion taking about two years.

Other consultants participating in the Forbes Road Emergency Slide Repairs project included: Michael Baker International, construction manager; American Geotechnical & Environmental Services, Inc., geotechnical engineering; Monaloh Basin Engineers, Inc., supplemental surveys and right-of-way plan quality assurance; and CDR Maguire, Inc., environmental services.