Backflow detection

Waste injection began in June 1975, and waste was first detected in the downgradient southwest deep monitoring well about 260 days later. To analyze the waste s physical and chemical properties after injection, the primary injection well was allowed to backflow into a holding pond for 5 days in November 1977. This waste was sampled periodically (and reinjected when the test was completed). About 4 years after injection began dilute waste arrived at the standby injection well 476 m (1560 ft) south of the primary well. 

Abstract Methods to infuse drugs into the parenchyma of the central nervous system (CNS) have been reported as inconsistent or unpredictable. The source of variability appears to be a compromised seal between the tissue and the outer surface of the cannula. Failure of the tissue to seal to the cannula creates a path of least resistance. Rather than penetrate the target area, the drug backflows along the path of the cannula. This artifact can be difficult to detect because drugs enter the systemic circulation and provide some fraction of the intended therapy. 

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