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Kansas Geological Survey, Open-file Report 88-39
Great Plains and Cedar Hills Aquifers--Page 18 of 25

7.0 Hydrogeologic Setting at the Monitoring Sites

7.1 Construction of the Multiple-Completion Monitoring Wells

The multiple-completion monitoring wells constructed during this investigation consist of two or more standpipe piezometers placed at various levels within a single steel-cased borehole. Each standpipe piezometer was positioned adjacent to an interval where the steel casing had been perforated. These intervals were carefully chosen from an examination of geophysical logs of the hole. Targeted zones for monitoring were chosen based on the likelihood of encountering porous and permeable zones. Each standpipe piezometer was constructed of Schedule 80, flush-joint, PVC pipe. For most of the piezometers, a ten-ft. section of well screen was attached at the bottom of the pipe string. The perforated interval of the borehole was then gravel-packed with a coarse-grained arkosic gravel. Zones above and below the gravel pack zone were back-filled with a coarse to fine-grained sand using a tremie pipe. Above the gravel pack and fill material zone, a plug of cement was carefully tremied into the hole to hydraulically isolate the lower monitored zone from the upper part of the borehole. This process was repeated with the construction and placement of each piezometer until the hole was filled to the surface. During the process, proper materials selection, careful placement of the gravel-pack, fill materials, and cement ensured that hydrologic isolation between observation points in the borehole was maintained.

Described below are hydrogeologic site conditions around each of the three multiple-completion monitoring wells at Gorham, Hays North, and Hill City.

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Kansas Geological Survey, Dakota Project
Original document dated December, 1988
Electronic version placed online April 1996
Scientific comments to P. Allen Macfarlane
Web comments to webadmin@kgs.ku.edu