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screened (or perforated) sections of the well which were designed for intake. These intervals usually require a separate episode of grouting to establish a floor for pressure grouting aquitards. Perforating well casing and pressure grouting using packers always requires numerous phased activities which makes the process time consuming, expensive, and often frustrating. For some wells with extensive filter packs, explosives have been used to perforate casing at aquitard intervals so that they may be cemented. In this process, explosive charges are attached to a wire line that is hung in the well with charges adjacent to aquitards and then detonated. When using explosives, the well bore should always be filled with water or cement during the actual blast so that geologic materials outside the well, especially below the water table, will not collapse back into the well after blasting. A collapsed well severely complicates and may prevent an effective decommissioning. After blasting, the top of the well casing should be sealed, preferably by welding, and cement pumped into the casing under pressure. The pressure causes cement to flow through breaches in the casing and invade and seal off aquitards. For wells deeper than 200 feet, injection pressures at the bottom of the well are much greater than the top which may reduce the effectiveness of pressure sealing shallow aquitards. Unfortunately, blasting does not provide for the confidence that is achieved by a phased decommissioning effort where the casing is mechanically perforated adjacent to aquitards and pressure grouted in lifts using a packer. Also, using explosives for decommissioning purposes is essentially a single-step aggressive activity. Unforseen mechanical breakdowns may severely compromise the process and generate additional corrective activities and expense. For these reasons, the use of explosives is generally discouraged. If a well filter pack annulus is at least four inches in diameter, dual-tube air rotary drilling (reverse circulation) can be used to only remove filter pack material. This technique creates an open annulus where the casing may be lifted and the open borehole sealed. For wells with filter packs to ground surface, dual-tube air rotary drilling may be used to remove annulus materials so that a near-surface sanitary seal can be installed. This technique should be used with caution and only if the relative consolidation of geologic materials penetrated by the well are known to be competent. The removal of a well filter pack Material for decommissioning or workover operations should definitely not be used where geologic materials are unconsolidated because the borehole may collapse. A collapsed borehole would severely complicate and possibly prevent an effective well decommissioning or annular seals. Cable Tool Wells and Blank Casing Cable tool and some types of rotary drilling employ a casing that is driven into the ground to keep the borehole open. Once a cable tool well is drilled, the casing is left in the borehole. After a 4