Due to new regulations, a temporary lined basin needed to be constructed to accept plant, process water. To prepare the sub grade, bottom ash and rock were excavated and removed from the site. A concrete forebay and five, 36” HDPE pipes were constructed and installed to maintain water flow. The completion of the project was the first of the multiple phases required to clean close the remaining basins.
“Trans Ash was able to overcome unexpected challenges and still complete the project ahead of schedule and under budget.”
Project Challenges & Solutions
Several items were encountered throughout the project life cycle, creating the following challenges:
- In order to deem the work area safe, the phreatic water level was monitored daily and had to remain below a specified elevation. Despite considerable effort, the basin, sub grade material did not respond to conventional dewatering methods. As a result, Trans Ash employed a water management subcontractor to install hundreds of well points and remove the sub surface water. The process was successful, and Trans Ash was able to maintain the phreatic water level below the specified elevation.
- During excavation an unexpected section of rock was encountered. Trans Ash utilized an excavator with a hammer attachment to demolish the rock, while working concurrently on other project activities. By adapting to the changing conditions Trans Ash was able to avoid delays and maintain the construction schedule.
- While excavating to reach sub grade, many areas were still too wet. Trans Ash focused its resources on digging sumps and over excavating. The sumps were able to remove the water long enough to allow stabilization of the undercut with stone and geogrid.
- The biggest challenge of the project was placing a sub grade of #57 stone, to grade, on the slopes of the forebay below the concrete. Trans employed an additional work force and multiple surveyors to continually check grade and adjustment, as necessary, to maintain grade until the concrete was ready to be poured.