17 JANUARY 2025 WorldWide Drilling Resource® Contamination Remediated with In Situ Stabilization Adapted from Information by Cascade Environmental Cascade Environmental managed multiple challenges, including unexpected soil conditions and utility issues at an active shipping facility that was a former paint manufacturing site. The site-specific contamination in the groundwater was Tert-butanol or tert-Butyl alcohol (TBA) and many more. The TBA was reportedly flushing from the area with seasonal groundwater flow from a former underground tank farm. The property owner worked with a third-party consultant and Cascade’s direct client to contract with multiple engineering companies to design a remedial approach to stop the release of TBA. The objective of the remedial plan was to isolate the flow of groundwater from the area to solidify and stabilize the contaminated soil using in situ solidification and stabilization (ISS). The company had to install an initial five-foot-wide, 20 to 33-foot-deep barrier slurry wall around the impacted area before conducting the full-scale ISS operations which was 405,000 cubic feet. The barrier wall was to cut off groundwater flow to and from the suspected TBA source, which was expected to be encountered between seven and 13 feet belowground. In addition, they had to remove concrete, asphalt, light poles, curbs, and fencing within the area, as well as identify and relocate an unspecified number of underground utilities. Cascade quickly identified why the TBA had become so mobile, and why former remedial work was not entirely effective. The area had been backfilled almost exclusively with bluestone, which undermined the soil and clay formations, creating voids where groundwater was settling, as well as contacting source material, and subsequently flushing into and contaminating seasonal groundwater flow. The bluestone also created an excavation issue because the stone did not set, stabilize, solidify, or hold appropriately. They siphoned out and filtered the groundwater, adding it to the slurry mixture being pumped back into the ground. The team was able to quickly respond to any situation and update the feasibility of the ISS mix design, the ISS approach, and material management. Another challenge was two conduits for electric and telecom proved to be over 14 conduits of unknown contents ranging from data, to electric, to fiber-optic, as well as a sanitary sewer line. Conduits had also been placed underground below groundwater, and replacing or rerouting conduits in the same area would not be safe or to code, so they had to proactively plan a new route with new manhole covers above the finished ISS grade, but safely below the eventual asphalt and parking lot. As the company identified more utilities, the team worked closely with the active site owner and a contracted electrician to identify their functions and relocate the utilities safely and legally within a week. As these challenges arose, Cascade addressed them by working diligently with the property owner, tenant, engineers, and client to provide and identify solutions. The need to collaborate with multiple parties and complete in situ remediation work in conjunction with utility relocation, temporary power, and space management made for a challenging and dynamic experience. Cascade completed all ISS remediation work and restored the area to existing or better conditions. Working diligently and thoughtfully, the company helped the engineer and client so both maintained their initial budgets. The project was finished six days ahead of schedule despite multiple setbacks and major changes in scope including change orders and unknown conditions in the field. The client, property owner, consultant, engineer, and current tenant were happy with the innovative and resourceful project execution. ENV
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