Water-Level Monitoring Plan for the Hanford Groundwater Monitoring Project
This document presents the water-level monitoring plan for the Hanford Groundwater Monitoring Project, conducted by the Pacific Northwest National Laboratory (PNNL). Water-level monitoring of the groundwater system beneath the Hanford Site is performed to fulfill the requirements of various state and federal regulations, orders, and agreements. The primary objective of this monitoring is to determine groundwater flow rates and directions. To meet this and other objectives, water-levels are measured annually in monitoring wells completed within the unconfined aquifer system, the upper basalt-confined aquifer system, and in the lower basalt-confined aquifers for surveillance monitoring. At regulated waste units, water levels are taken monthly, quarterly, semi-annually, or annually, depending on the hydrogeologic conditions and regulatory status of a given site. The techniques used to collect water-level data are described in this document along with the factors that affect the quality of the data and the strategies employed by the project to minimize error in the measurement and interpretation of water levels. Well networks are presented for monitoring the unconfined aquifer system, the upper basalt-confined aquifer system, and the lower basalt-confined aquifers, all at a regional scale (surveillance monitoring), as well as the local-scale well networks for each of the regulated waste units studied by this project (regulated-unit monitoring). The criteria used to select wells for water-table monitoring are discussed. It is observed that poor well coverage for surveillance water-table monitoring exists south and west of the 200-West Area, south of the 100-F Area, and east of B Pond and the Treated Effluent Disposal Facility (TEDF). This poor coverage results from a lack of wells suitable for water-table monitoring, and causes uncertainty in representation of the regional water-table in these areas. These deficiencies are regional in scale and apply to regions outside of the operational areas, so these deficiencies do not in anyway reflect on the adequacy of the local-scale well networks used for regulated-unit monitoring. The sediments comprising the unconfined aquifer system have been subdivided into nine hydro-geologic units. The specific hydrogeologic units present within the saturated open interval of each onsite well used for water-level measurements are identified. This was accomplished by geologic interpretation at individual wells combined with extrapolation to nearby wells using a three-dimensional, regional-scale conceptual model of the Hanford Site hydrostratigraphy.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 12228
- Report Number(s):
- PNNL-13021; TRN: AH200119%%397
- Resource Relation:
- Other Information: PBD: 30 Sep 1999
- Country of Publication:
- United States
- Language:
- English
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