Three reactive chemical barriers were emplaced at the Fry Canyon demonstration site during August/September 1997 using simple, inexpensive, and well-established construction methods. Many small active and abandoned mine and mill sites throughout the Western United States are suitable for using these methods.
Initial excavation of the barrier trench. (49k)
Reactive chemical barriers after backfilling. (56k)
Phosphate reactive chemical barrier and associated monitoring
points after reaching final grade. (49k)
Approximate location of the reactive chemical barriers. (17k)
Schematic diagram of monitoring points in the PO4 reactive chemical barrier.
(11k)
The three barriers consist of (1) Cercona Bone Char Phosphate (PO4), (2) Cercona foamed zero valent iron (ZVI) pellets, and (3) amorphous ferric oxide (AFO). Each barrier is heavily instrumented to assess and compare barrier performance during the demonstration project. Four transducers, one water-quality minimonitor (measuring temperature, pH, specific conductance, oxidation reduction potential, and dissolved oxygen), and a flow sensor are deployed in each barrier. Data from the transducers and minimonitor are recorded hourly. Flow direction and velocity are measured monthly. In addition, each barrier has a total of 20 monitoring points for the collection of water-quality samples. Four monitoring points are located downgradient of the barriers in the colluvial aquifer.
Reactive material (Cercona Bone Char Phosphate) being dumped
into the gate structure of the reactive chemical barrier.
Reactive chemical barrier gate structures and monitoring ports
prior to backfilling with native material