Performance assessment of a pump-and-treat (P&T) system to support a decision about whether it is appropriate to shut down the system can be facilitated by using a structured approach that included consideration of decision elements. Decision elements involve assessment of contaminant concentrations and trends; contaminant mass discharge from source areas; the attenuation capacity of the aquifer; estimated future plume behavior; and P&T system design, operational, and cost information to identify an appropriate condition for transitioning from P&T remediation. It is also important to consider site-specific factors. Thus P&T system performance assessment for the Hanford Site should be specific to the plumes, environmental setting, and design/operational approaches for Hanford Site P&T systems.
In fiscal year 2017, PNNL worked with 200-ZP-1 operable unit (OU) and 100-HR-3 OU staff in preparing OU documents associated with implementation of P&T remedies. In these efforts, elements of a structured approach to P&T decisions and Hanford-specific factors were incorporated into the documents. Because the 200-ZP-1 and 100-HR-3 OU documents are still in a draft stage at the time this report was written, the information provided here serves only as an example of how to map P&T decision elements to performance monitoring and work plans for P&T systems. Final remedy documentation for these OUs should be consulted for specific information on OU plans and activities.
Revised: December 27, 2018 |
Published: October 2, 2017