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.  Request 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.

PRODUCT FEATURE

Well Development Tool
Once your 2.0 in. prepacks are installed, you need to develop the well properly. The new 2.0-in. Well Development Tool is equipped with a flexible polyurethane collar to help surge water into and out of the screen during the development process. The development tool attaches to nominal 0.5-in. PVC riser so it can be lowered into the well and efficiently raised and lowered to surge and purge the well. Movement of water into and out of the screen provides for better development and removal of fines around the well interval. A check valve in the tool allows you to purge water from the well while surging to help remove the fines and provide for good hydraulic communication between the well and formation. It's best to develop segments of the screen and move up and down through the screen interval repeatedly to achieve adequate development. Review ASTM Standard D 5521 for additional guidelines and information on well development techniques and purposes.

2.0 in. Well Development Tool Operation
Valve Closed Downstroke of tool surges groundwater into formation. Work incrementally up and down through the screen interval.	Valve Closed Upstroke of tool surges groundwater and fines from formation into the well.	Valve Open Start with valve open and purge to establish flow into the well. Oscillation of tool pumps groundwater from well.