ABSTRACT
CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 849 Monitoring Well Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 850
General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 850 AirLift Surging and Pumping with Compressed Air . . . . . . . . . . . . . . . . . . . . . . . . . 855 Mechanical Surging and Pumping with a Surface Centrifugal Pump . . . . . . . . . . . 857 Mechanical Surging and Pumping with a Submersible Pump . . . . . . . . . . . . . . . . . 857 Mechanical Surging with a Surge Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 858 Valved and Air-Vented Surge Plunger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 859 Mechanical Surging with a Bailer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 859 Manual Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 860 High-Pressure Water Jetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 860 Decontamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 861 Surveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 861 Well Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 864
Reporting Well Construction Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 866 Monitoring Well Maintenance and Rehabilitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 868 Monitoring Well and Borehole Decommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872
Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872 Planning for Decommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 872 Location and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 875 Decommissioning Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 875 Placing Abandonment Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 877 Procedures for Decommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 878 Records and Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 880
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 881
Following the installation of a monitoring well or monitoring system, several important issues must be addressed to ensure the well’s or system’s integrity, identity, and longterm operation. This chapter covers a variety of important monitoring well post-installation considerations including: well development, surveying, identification, reporting of construction details, maintenance and rehabilitation, and abandonment. Monitoring well
development is very important in terms of ensuring collection of representative data from a well because it is the activity performed in the well to correct damage done during drilling to the formation surrounding the borehole, and to remove fine materials (silt, clay, fine sand) and drilling fluids from the filter pack and the formation in the immediate vicinity of the well. This is done to provide maximum efficiency and hydraulic communication between the well and the adjacent formation to ensure that future formation hydraulic conductivity test results are of maximum value and to ensure that representative ground-water samples may be collected in the future. Surveying of monitoring wells to a common datum is necessary to obtain accurate water-level data, to construct ground-water contour maps, and to allow the correlation of stratigraphic horizons from well to well and the subsequent development of hydrogeologic cross-sections. Proper well identification and complete reporting of monitoring well construction details are necessary elements of documentation. Monitoring well maintenance and rehabilitation are necessary to keep wells operational and to maximize the life of a well system. Monitoring well decommissioning (also called “abandonment”) is required to mitigate the potential for an unused, unnecessary, or malfunctioning well to become a vertical conduit for contaminant migration. Each important element of a ground-water monitoring program is discussed in the following sections.
