Water-level sensors (Water Logger WL-15 units from Global Water) were installed by BCRET on Fields 5a and 12 to continuously monitor the water table depth along two transects in Field 12 and in several strategic locations in Field 5a. The soil water-level sensors determine the depth at which soil is saturated with water (or the water-table depth) at four-hour intervals down to average depths of 6 to 7 feet, with the deepest being 9.7 feet below the surface, which is the depth where soil was underlain by a cherty or discontinuous layer (i.e., point of refusal).
At each site, two piezometers were also installed that allow collection of an in-situ soil water sample. The piezometers consist of 5-cm (2-inch) diameter Schedule 40 PVC pipe, which were slotted in the bottom 10 cm of the pipe to facilitate water flow. Sand was placed in the bottom of the hole and along the outside of the PVC pipe up to the top level of the slots in the pipe. Bentonite chips were placed above the sand along the outside of the PVC pipe to the soil surface to ensure no preferential movement of water along the well casing. Piezometers were installed so that there was no piping or equipment above ground that could interfere with day to day farm operations on the field.
Data is downloaded from each unit using a laptop computer approximately once a month. One piezometer was located to collect water from just below the root zone (about 12 inches deep) and one from the deeper point of refusal, described above.