This ICN updates the groundwater monitoring plan. The list of constituents and the frequency of sampling is updated to reflect current needs and updates the list of wells within the network.
During 2003, the upgradient well 299-W26-7 went dry and one new groundwater monitoring well was installed downgradient (well 299-W26-14) of the 216-S-10 pond and ditch. This ICN updates the groundwater monitoring wells for the 216-S-10 pond and ditch and adds a revised well location map to the plan.
This form updates the groundwater monitoring plan for the B Pond system and documents revision agreed upon with the Washington State Department of Ecology concerning well network, constituent list, statistical analysis, and report procedures.
This document outlines the groundwater monitoring plan, under RCRA regulations in 40 CFR 265 Subpart F and WAC173-300-400, for the 216-B-63 Trench. This interim status facility is being sampled under detection monitoring criteria and this plan provides current program conditions and requirements.
The 216-B-3 Pond was a series of ponds for disposal of liquid effluent from past Hanford production facilities. In 1990, groundwater monitoring at B Pond was elevated from "detection" to assessment status because total organic halides and total organic carbon were found to exceed critical means in two wells. Groundwater quality assessment, which ended in 1996, failed to find any specific hazardous waste contaminant that could have accounted for the isolated occurrences of elevated total organic halides and total organic carbon. Hence, the facility was subsequently returned to detection-level monitoring in 1998. Exhaustive groundwater analyses during the assessment period indicated that only two contaminants, tritium and nitrate, could be positively attributed to the B Pond System, with two others (arsenic and I-129) possibly originating from B Pond. Chemical and radiological analyses of soil at the main pond and 216-B-3-3 ditch has not revealed significant contamination. Based on the observed, minor contamination in groundwater and in the soil column, three parameters were selected for site-specific, semiannual monitoring; gross alpha, gross beta, and specific conductance. Total organic halides and total organic carbon are included as constituents because of regulatory requirements. Nitrate, tritium, arsenic, and iodine-129 will be monitored under the aegis of Hanford site-wide monitoring. Although the B Pond System is not scheduled to advance from RCRA interim status to final status until the year 2003, a contingency plan for an improved monitoring strategy, which will partially emulate final status requirements, will be contemplated before the official change to final status. This modification will allow a more sensible and effective screening of groundwater for the facility.