RESULTS OF TRITIUM TRACKING AND GROUNDWATER MONITORING AT THE HANFORD SITE 200 AREA STATE APPROVED LAND DISPOSAL SITE FY2008

[摘要] The Hanford Site's 200 Area Effluent Treatment Facility (ETF) processes contaminated aqueous wastes derived from Hanford Site facilities. The treated wastewater occasionally contains tritium, which cannot be removed by the ETF prior to the wastewater being discharged to the 200 Area State-Approved Land Disposal Site (SALDS). During the first 11 months of fiscal year 2008 (FY08) (September 1, 2007, to July 31, 2008), approximately 75.15 million L (19.85 million gal) of water were discharged to the SALDS. Groundwater monitoring for tritium and other constituents, as well as water-level measurements, is required for the SALDS by State Waste Discharge Permit Number ST-4500 (Ecology 2000). The current monitoring network consists of three proximal (compliance) monitoring wells and nine tritium-tracking wells. Quarterly sampling of the proximal wells occurred in October 2007 and in January/February 2008, April 2008, and August 2008. The nine tritium-tracking wells, including groundwater monitoring wells located upgradient and downgradient of the SALDS, were sampled in January through April 2008. Water-level measurements taken in the three proximal SALDS wells indicate that a small groundwater mound is present beneath the facility, which is a result of operational discharges. The mound increased in FY08 due to increased ETF discharges from treating groundwater from extraction wells at the 200-UP-l Operable Unit and the 241-T Tank Farm. Maximum tritium activities increased by an order of magnitude at well 699-48-77A (to 820,000 pCi/L in April 2008) but remained unchanged in the other two proximal wells. The increase was due to higher quantities of tritium in wastewaters that were treated and discharged in FY07 beginning to appear at the proximal wells. The FY08 tritium activities for the other two proximal wells were 68,000 pCi/L at well 699-48-77C (October 2007) and 120,000 pCi/L at well 699-48-77D (October 2007). To date, no indications of a tritium incursion from the SALDS have been detected in the tritium-tracking wells. Concentrations of all chemical constituents were within Permit limits or were below method detection limits when sampled during FY08. A summary of the chemical constituent concentrations or method detection limits is provided in Table 3-2 in the main text discussion. This report presents the results of groundwater monitoring and tritium-tracking samples from the SALDS facility during FY08. Due to the 30-day laboratory turnaround for analysis of proximal well groundwater samples, this report addresses available date extending from August 1, 2007, through September 30, 2008 (August 2007 data were not included in the FY07 report). Updated background information, which is necessary to understand the results of the groundwater analyses, is also provided on facility operations. Interpretive discussions and recommendations for future monitoring are also provided, where possible.

[发布日期] 2008-11-19

[学科分类] 核能源与工程

[关键词] AR FACILITIES;HANFORD RESERVATION;GROUND WATER;MONITORING;SAMPLING;TRITIUM;RADIOACTIVE WASTE FACILITIES;WATER TREATMENT;RADIOECOLOGICAL CONCENTRATION