PrePack Wells
We are pleased to announce that ZEBRA Environmental is now installing 2” ID Prepacks.
With the increase in strength of our fleet of Geoprobe series 7700 & 6600’s coupled with the
availability of larger diamter casing placing the 2” ID Prepack monitoring and injection wells
is a viable alternative to conventional drilling. Here is why more ground water professionals
are using Prepack Wells?
Well Screens designed for setting Small Diameter Monitoring Wells. Pre-pack well screens are available in two outside diameters� 35 mm OD (12 or 20 mm ID) and 62 mm OD (25 or 37 mm ID).
To install a monitoring well with these pre-packs, probe rods are first driven to depth with a Geoprobe percussion probing machine.
The well assembly is then lowered into the probe rod string with threaded PVC riser pipe.
The small diameter pre-pack well screen assembly uses 12 mm PVC riser pipe and is installed with 2.125-inch OD probe rods. The larger diameter pre-pack well assembly uses 25 mm PVC riser pipe and is installed with 3.25-inch OD probe rods.
Once the well assembly is lowered to the bottom of the probe rod string, the probe rods are retracted to a point above the screen.
A sand barrier, installed directly above the well screen, prevents grout from entering the screens.
This barrier can be created either by natural formation collapse (occurring during the initial probe rod retraction) or by gravity installation of fine-grade sand through the rod annulus. With the barrier in place, granular bentonite or bentonite slurry is then installed in the annulus to form a well seal.
Advantages
♦ The most cost effective method for
installing permanent monitoring wells.
♦ Available in sizes ranging from 0.5-inch through 2-inch I.D.
♦ Manufactured using PVC and high quality stainless steel screens to assure high integrity samples.
♦ Assures accurate placement of filter media across desired interval.
♦ Quick Seal and Bentonite sleeves protects the sampling environment.
♦ Installed through cased borehole, provides high integrity well construction and sample quality.
♦ Meets ASTM standard D6725 for Direct Push Monitoring Well Installation.
♦ Meets basic EPA and RCRA construction requirements.
♦ DOD and EPA Studies reveal no
statistically significant difference
between water quality samples collected from paired Pre-Packs and conventional drilled wells.
