Groundwater monitoring plan for the Hanford Site 200 Area Treated Effluent Disposal Facility

Technical Report · Wed May 17 04:00:00 EDT 2000

DOI:https://doi.org/10.2172/754948· OSTI ID:754948

Barnett, DB ^[1]

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1. PNNL

Seven years of groundwater monitoring at the 200 Area Treated Effluent Disposal Facility (TEDF) have shown that the uppermost aquifer beneath the facility is unaffected by TEDF effluent. Effluent discharges have been well below permitted and expected volumes. Groundwater mounding from TEDF operations predicted by various models has not been observed, and waterlevels in TEDF wells have continued declining with the dissipation of the nearby B Pond System groundwater mound. Analytical results for constituents with enforcement limits indicate that concentrations of all these are below Practical Quantitation Limits, and some have produced no detections. Likewise, other constituents on the permit-required list have produced results that are mostly below sitewide background. Comprehensive geochemical analyses of groundwater from TEDF wells has shown that most constituents are below background levels as calculated by two Hanford Site-wide studies. Additionally, major ion proportions and anomalously low tritium activities suggest that groundwater in the aquifer beneath the TEDF has been sequestered from influences of adjoining portions of the aquifer and any discharge activities. This inference is supported by recent hydrogeologic investigations which indicate an extremely slow rate of groundwater movement beneath the TEDF. Detailed evaluation of TEDF-area hydrogeology and groundwater geochemistry indicate that additional points of compliance for groundwater monitoring would be ineffective for this facility, and would produce ambiguous results. Therefore, the current groundwater monitoring well network is retained for continued monitoring. A quarterly frequency of sampling and analysis is continued for all three TEDF wells. The constituents list is refined to include only those parameters key to discerning subtle changes in groundwater chemistry, those useful in detecting general groundwater quality changes from upgradient sources, or those retained for comparison with end-of-pipe discharge chemistry. Volatile and semivolatile organic compounds, ammonia, total organic carbon, oil and grease, and radium are removed from the constituent list. Annual analysis for low-level tritium is added to the constituent list to help confirm that groundwater beneath the TEDF remains isolated from operational influences.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 754948
• Report Number(s): PNNL-13032
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
AQUIFERS
ENVIRONMENTAL EFFECTS
GEOCHEMISTRY
GROUND WATER
HANFORD RESERVATION
MONITORING
ORGANIC COMPOUNDS
RADIOACTIVE WASTE FACILITIES
SAMPLING
TRITIUM