Water monitoring sites are sampled for the purposes of examining trends of INL contaminants and other general ground water quality indicators and for verifying DOE monitoring results. Sites sampled include ground water locations (wells and springs), surface water locations (streams), and selected wastewater sites.

Sample sites have been selected to aid in identifying INL impacts on the Eastern Snake River Plain Aquifer (ESRPA), and are categorized as up-gradient, facility, boundary, distant, surface water, and wastewater.

• Up-gradient locations are not impacted by INL operations and are considered representative of background ground water quality conditions.
• Facility sites are sample locations on the INL near facilities, in areas of known contamination, or wells selected to illustrate trends for specific INL contaminants or indicators of ground water quality. 
• Boundary locations are on or near the perimeter of the INL or are down-gradient of potential sources of INL contamination. 
• Distant locations are monitored to provide trends in water quality down-gradient of the INL and include wells and springs used for irrigation, public water supply, livestock, domestic, and industrial purposes. 

During the first quarter of 2006, one up-gradient location, seven facility locations, one boundary location, and five distant locations were sampled.

Gross alpha radioactivity was detected at two facility and one distant locations.  There were no detections in up-gradient, boundary, or surface water samples.  Gross alpha detections were within the expected range for naturally-occurring radioactivity.  Gross beta radioactivity was detected in each of the four areas (up-gradient, facilities, boundary and distant) and in both surface water samples.  As expected, the highest concentrations of gross beta radioactivity were found at facility locations with known historic INL contamination.  Concentrations observed were consistent with historical trends.  No man-made, gamma emitting radionuclides were identified. 

Three of eight location samples analyzed for strontium-90 had detectable results.  Two of these sites were above the MCL.  The concentrations are consistent with historical trends.

One boundary and ten facility location samples were analyzed for technetium-99.  Most results were consistent with historic concentrations.  The maximum value was for a sample from well USGS-106.  This result was unusual due to the significant increase from previous sampling, and the apparent absence of other radionuclides that would be expected to accompany this INL contaminant.  ISU-EML review of this result from USGS-106 did not indicate an obvious laboratory error.  DEQ-INL will continue to sample this well for INL contaminants including technetium-99. 

Two facility locations (M1S and M3S) were analyzed for isotopes of plutonium and americium.  A detectable concentration for plutonium-239/240 was reported for a sample from M1S. DEQ-INL and ISU-EML investigated the result and submitted an archived sample from M1S collected at the same time to Paragon for analysis.  This follow-up analysis will be reported when complete.  There were no detectable results for americium-241.  Three sites were also sampled for isotopes of uranium.  Each had detectable results for uranium-234 and uranium-238, and one site had detectable results for uranium-235.  The ratios of results observed for uranium isotopes were consistent with historical results and cannot be distinguished from background concentrations.  This means the uranium found in these samples is likely from natural sources. 

Using the standard analytical method, tritium was detected at ten of the samples from facility locations.  Results are consistent with historic trends of decreasing concentrations.  There was one detectable concentration in a boundary sample, but none in up-gradient, distant, or surface water sites. 

All common ion, nutrients, and metals results were within their expected ranges, depending on sample location and extent of contamination in specific areas.

The background concentrations for VOCs should be zero.  The results discussed in this section only refer to detectable concentrations.  Four facility locations were sampled for VOC’s this quarter.  M3S was the only location with detectable concentrations of VOCs.  Trichloroethylene (TCE) was measured at a concentration of 0.93 µg/L, and carbon tetrachloride was measured at 3.7 µg/L, both are below their respective MCL of 5 µg/L.  All of the locations monitored for VOCs are within areas of known contamination.

For a complete description of monitoring during the 2nd quarter of 2006, see Oversight’s Environmental Surveillance Program Quarterly Data Reports.