Well Drilling & Groundwater Monitoring

Conversion of Characterization Wells to Groundwater Monitoring Wells

As part of the 1998 to 2005 characterization program outlined by the Hydrogeologic Work Plan, 33 wells (designated as R-wells) were drilled. It was anticipated that characterization wells might eventually become part of a groundwater monitoring network. Concerns were raised that some R-wells might not be suitable for monitoring because fluids used in the drilling process were not completely removed. Remnants of these fluids could impact the ability of the wells to provide representative groundwater data and compromise the ability to detect reactive contaminants. The Laboratory conducted an extensive analysis of the 33 R-wells (documented in the Well Screen Analysis Report), on a screen-by-screen basis.

The Well Screen Analysis Report results indicated that, for the 64 screens analyzed, 16 of the wells had screens that were in Fair or Poor condition and could not be relied upon to provide representative data or to detect contaminants in groundwater. These results prompted the New Mexico Environment Department in its reply to the Laboratory’s Interim Facility-wide Groundwater Monitoring Plan to request the Work Plan for R-Well Rehabilitation and Replacement.

Individual screens for all R-wells were evaluated. Of the 16 out of 33 wells with screens that scored Fair to Poor, two—R-16 and R-20—were selected for a pilot well rehabilitation study conducted in the summer of 2006. The Work Plan for R-Well Rehabilitation and Replacement is informed by the pilot study.

This Work Plan for R-Well Rehabilitation and Replacement explains the selection of wells for rehabilitation, the rehabilitation methods, and the measures to evaluate the degree of success of rehabilitation. The collective results of rehabilitation efforts in FY07, along with insights gained from the FY06 pilot study, will be used to guide decisions made for wells in FY08 and to refine the methods used in their rehabilitation.

In addition to reporting the results of the redevelopment process in the annual update to Work Plan for R-Well Rehabilitation and Replacement, results also will be discussed and interpreted in a 2008 update of the Well Screen Analysis Report, which will provide a more comprehensive discussion of well conditions and the degree of success of the rehabilitation efforts.

Document Links

• Hydrogeologic Work Plan
• Hydrogeologic Synthesis Report
• Well Screen Analysis Report
• Interim Facility-wide Groundwater Monitoring Plan
• Well Rehabilitation Pilot Project
• Work Plan for R-Well Rehabilitation and Replacement

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• Review of November 2008 Groundwater Data

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