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ENVIRONMENTAL CONSTRUCTION AND REMEDIATION Test Section Of Chemical Treatment Wall This project included the construction of a Test Section of the Chemical Treatment Wall (CTW) at the Somersworth Sanitary Landfill Superfund Site (the "Site") to demonstrate the overall constructability of the CTW using the BP method and to evaluate the potential effects of the BP slurry on the iron/sand mixture to be used in the CTW.
The project consisted of excavating a 2-foot trench to bedrock surface (approximately 31 feet) under B-P slurry. The trench was constructed on the alignment of the full-scale CTW between Stations 0+00 and 0+25. The trench was backfilled with an iron/sand mixture pertaining to SegmentŠ1 of the CTW. The mixing of the iron and sand was performed using concrete mixing trucks and was placed into the trench via a tremie tube. After the placement of the backfill, the degradable B-P slurry was broken to water.
The main challenges on this project were to: 1) avoid iron/sand mixture segregation during and after the mixture placement in the trench and 2) have minimum contact of slurry with iron in the iron/sand mixture. Mixture segregation was avoided by tremieing the mixture into the trench. To minimize slurry contact with iron, the iron/sand mixture was wetted with water to fill the pore spaces before placing into the trench.
The performance of the Test Section is being monitored during the winter by Geo-Syntec, the consultant for the project. Following their monitoring and evaluation, the full scale CTW is scheduled to be constructed in July 2000.
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