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REPORT DATE
MAR 20082
PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Oregon Health and Science University 8. PERFORMING ORGANIZATION REPORT NUMBER
SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)
SPONSOR/MONITOR'S REPORT NUMBER(S)
DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release, distribution unlimited
SUPPLEMENTARY NOTESThe original document contains color images. IMPLEMENTATION ISSUES ........................................................................................ ....................................................................................................................... 39 9. POINTS OF CONTACT ...................................................................................................
Demonstration DesignThis report evaluates an approach in which granular iron was placed outside of the well screens in a pair of dual-screened wells. The wells were installed inside a large diameter temporary casing such that the iron adjacent to the upper and lower screens could be isolated from one another in a manner which would promote groundwater circulation between the pair of dualscreened wells.
Summary of ResultsThe groundwater hydrology of the well pair was evaluated, and met design expectations. A primary concern in the methodology was that water entering the treatment zone would contain materials (e.g., sulfate) that would plug the treatment zone over time. Based on our calculations for the site, this was not expected to be a problem, which turned out to be the case. Unfortunately, an unanticipated problem arose in which water moving out of the upper screen (which was located near the water table) became oxygenated and plugged the treatment zone. An additional problem with oxygen arose because of regionally-decreasing water table elevations in the area of the demonstration. This exposed a portion of the iron adjacent to the upper screen and, together with drawdown during pumping, led to a loss of permeability in the well in which water was extracted from the upper screen. These problems could have been avoided if the screened interval was below the water table, and if a pac...