Evaluation of a multiport groundwater monitoring system

Abstract

In 1988 and 1989, Pacific Northwest Laboratory installed a multiport groundwater monitoring system in two wells on the Hanford Site: one near the 216-B-3 Pond in the center of the Hanford Site and one just north of the 300 Area near the Columbia River. The system was installed to provide the U.S. Department of Energy with needed three-dimensional data on the vertical distribution of contaminants and hydraulic heads on the Hanford Site.This study evaluates the ability of the multiport system to obtain hydrogeologic data at multiple points vertically in a single borehole, and addresses the representativeness of the data. Data collected from the two test wells indicate that the multipart system is well suited for groundwater monitoring networks requiring three-dimensionalcharacterization of the hydrogeologic system. A network of these systems could provide valuable information on the hydrogeologic environment. However, the advantages of the multipart system diminish when the system is applied to long-term monitoring networks (30+ years) and to deeper wells (<300ft). For shallow wells, the multipart system provides data in a cost-effective manner that would not be reasonably obtainable with the conventional methods currently in use at the Hanford Site.

Considering barometric pressure in groundwater flow investigations

“…This closed‐well installation provided access to four separate depth intervals using a Westbay Instruments Multiport (MP™) system. A detailed description of the test facility is given by Gilmore [1989] and Gilmore et al [1991]. The lower three ports were monitored during this period and provided nearly identical total head measurement patterns.…”

Comparison of constant-rate pumping test and slug interference test results at the Hanford Site B pond multilevel test facility

“…Multilevel monitoring facilities have been installed to provide detailed, vertically distributed hydrologic characterization information for the Hanford Site unconfined aquifer. In previous reports, vertically distributed water-level and hydrochemical data obtained over time from these multi-level monitoring facilities have been evaluated and reported (e.g., Gilmore et al 1991). …”

“…A Westbay Modular Subsurface Data Acquisition System (MOSDAXTM) was used to measure and record hydraulic pressure simultanepusly in all of the monitored intervals. Although the MP system at well 699-43-42K had a total of eight monitoring intervals, damage that occurred previously during the installation of the MP system (Gilmore et al 1991) eliminated the possibility of monitoring responses in the lower four zones. A more detailed description of the test facility is presented in Gilmore (1989), Gilmore et al (1991), and Thorne et al (1993).…”