Monitoring Well Installation & Sampling
Advantage Probe & Injection Corp installs 1.5” monitoring wells using our 6600 series unit via direct push as an alternative to 2-inch wells installed using an auger drill rig. 1.5” wells can be installed rapidly to depths in excess of 50 feet (subsurface dependent) to acquire large quantities of groundwater or for long-term monitoring. Ten or more wells can be installed per day at a cost substantially lower than traditional drill rigs. Wells can be installed with a "J" plug lockout and a seven-inch manhole cover can set in concrete, or with a "stick-up" completion and protective bumper posts, depending on site conditions.
To install a monitoring well, 3.25” 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. 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 of Small Diameter Monitoring Wells
Smaller subsurface disturbance. Smaller subsurface disturbance reduces the area for surface water to enter the borehole, which is the main purpose of the bentonite seal.
Reduced Installation Costs and Time. Installation of small diameter wells cost approximately 1/3 of the cost of a 2-inch monitoring well. Well materials are less expensive and installation can be completed in less than an hour (depending on site conditions). Reduced installation expense allows additional investigation points, therefore increasing confidence in identifying the extent and magnitude of groundwater contamination.
Reduced Sampling Costs and Time. Sampling procedures require the removal of three well volumes prior to sampling. Small diameter wells have smaller well volume, thereby reducing sample time and project costs.
Minimal Waste Generation. Direct-push sampling creates little or no drill cuttings, reducing the problem and expense of drill cuttings disposal.
Piezometer/Sparger Implants. APIC has the ability to install 3/4-inch PVC or steel piezometers using the Geoprobe system. The type and size of piezometer to be installed depends on the soil characteristics and the objective of the project. Piezometers can be used to determine groundwater flow direction, and to monitor contaminant migration.
Injection of Remedial Compounds (ORC). We have the ability, experience and expertise required to inject oxygen release compound ORC as part of the remediation of a site. APIC utilizes Geoprobe rod accessories and grout pump (GS-2000) to inject ORC at desired depths and intervals. APIC is capable of “bottom up” or “top down” injections.
