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Chemical Road Emergency Repairs

Project Details
Location:Plymouth Township, Montgomery County, PAClient:PennDOT District 6-0Completion Date:2022Share

Our first assignment under the District 6-0 Geotech Open End was to provide design services for an emergency project. Due to various local sinkholes and subsequent major subsidence of the roadway embankment, a stretch of Chemical Road from the I -476 off ramp to West Germantown Pike in Plymouth Township was closed to traffic. Considering the extent of damage and high traffic volumes, this project was granted an emergency declaration and immediate action was required. 

Our team, (Schnabel, TPD, and Susquehanna Civil), was tasked with providing initial funding estimates, completing a design, letting the project, and developing a construction concept that could be completed by December 2021. Seeing that the project team was only first notified of the project at the first of the year and provided Notice to Proceed in March of 2021, this was a challenging schedule to say the least.

The project technically consisted of the use of sophisticated nondestructive subsurface exploration techniques combined with traditional geotechnical borings, past plan information, and support field observations to best assess the underlying problem. Based on Schnabel’s assessments, a high-pressure grouting program consisting of a dense grid of borings to inject grout was used to strengthen the embankment while also filling sinkhole voids. Additionally, ground level soft spot excavations and stone backfill were required, along with steam channel sinkhole remediation techniques. These operations became more complex and troublesome considering numerous utility lines running parallel to the roadway with various unidentified laterals. A well thought out plan toward utility research, locating, and related specifications and plan details was needed to avoid relocation and project delays. These coordination efforts were made more difficult considering the tight schedule. The utility network was a puzzle pieced together quickly using a combination of quick low-cost ground penetrating radar technology, old plans, and above ground survey and utility company contact coordination. We were able to leverage the emergency project designation and timeline to obtain better utility compliance and cooperation.

Schedule time constraints also complicated permitting issues. The project team first acquired an emergency permit to cover any potential work required if a sudden embankment failure forced a more rapid construction rehabilitation response. Concurrently, the process of obtaining a small projects permit was started and continued until approval, with this falling into place as the Emergency permit expired.

The project design team was able to beat the project schedule. The project was ultimately let and won by Road Con and construction work is nearing completion with few change orders being required.

All involved with the project responded quickly and worked the extra hours when needed. These extra efforts were greatly appreciated by PennDOT, and to date the team has received high praise from PennDOT personnel involved in the project.