Prepacked Screen Monitoring Well Installation
Prepacked Screen Monitoring Wells from Geoprobe Systems® have been installed in various types of soil compositions including alluvial sediments consisting of clays, silts, and sands with fine to medium gravels at depths exceeding 60 feet. The time required for installation and grouting one of these wells varies from approximately one to four hours depending on the depth, site specific conditions, and experience of the operators.
Several steps can be followed to facilitate prepacked screen installation. Get your copy of one of the Monitoring Well SOPs for a detailed installation guide.
Prepack installation breaks down into these steps:
- Understand the site's lithology
- Determine the appropriate prepack size
- Drive the probe rods
- Install the prepack(s) and riser
- Create the grout barrier
- Grout the well
- Develop the well
- Sample the well
A conductivity log (right) shows distinctive clay layers within saturated sands at a research project in Central Kansas. These are alluvial deposits. A thin, distinct sand lens is indicated at 20 feet with confining clays at 40 to 42 feet (12.2 to 12.8 m) and at 45 to 47 feet (13.7 to 14.3 m). Prior to setting the prepacked screen monitoring wells, a LB soil sample was taken from 45 to 47 feet bgs. The sample consisted of a dark, gray-black clay at the 45- to 47-foot interval correlating exactly with the conductivity log.