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Battle Mountain Resources—San Luis SL-SOP-Groundwater Well Decommissioning <br /> STANDARD OPERATING PROCEDURES 11 REVISION: 0-May 6,2019 <br /> low permeability is known as a confining layer. Contamination in the overburden <br /> lying above a confining layer is a significant condition to recognize. To prevent mobile <br /> contaminants from crossing a confining layer during pulling or over-drilling, a <br /> temporary casing should be installed to isolate the work zone. One should follow the <br /> procedure selection flow chart. Some contaminated conditions call for over-drilling or <br /> a specially designed procedure. <br /> A well in contaminated overburden may be grouted in-place as long as the grout fully <br /> seals the well and boring zone. If a well in contaminated overburden was constructed <br /> allowing formation collapse as annular backfill or if the well has a compromised well <br /> seal, one must either physically remove the well or thoroughly perforate the riser and <br /> grout it in-place. <br /> If physical removal of the well is required and the overburden contaminants are likely <br /> to be dragged upward or downward during decommissioning, a temporary casing <br /> should be used to seal off the construction work zone. Casing pulling and over-drilling <br /> can be safely accomplished within the temporary casing. Section 4.4 discusses the <br /> temporary casing technique. <br /> 5.4. Telescoped Riser <br /> If the riser is telescoped in one or more outer casings, the decommissioning approach <br /> depends upon the integrity of the well seal. If there is no evidence that the well seal <br /> integrity is compromised, the riser should be grouted in-place in accordance with <br /> Sections 4.1 or 4.2 and the upper 5 feet of the well surface should be restored in <br /> accordance with Section 9. If indications are that the well seal is not competent, it <br /> will be necessary to design and implement a special procedure to perforate and grout <br /> or remove the well construction materials. The presence and configuration of the <br /> outer casing(s) will be specific in the individual wells and will be a key factor in the <br /> decommissioning approach. The special procedure must mitigate the potential for <br /> cross-contamination during removal of the well construction materials. <br /> 6. LOCATING AND SETTING-UP ON THE WELL <br /> Prior to mobilizing to decommission a monitoring well, one should notify the property <br /> owner and/or other interested parties including the governing regulatory agency. It is <br /> advisable that when at the well location, one should review the proposed well <br /> decommissioning procedure. Verify well locations and identification by their identifying <br /> markers and GPS coordinates. Lastly, verify the depth of each well with respect to depth <br /> recorded on the well construction log. <br /> 7. REMOVING THE PROTECTIVE CASING <br /> Most monitoring wells installed in non-traffic locations are finished with an elevated, <br /> protective casing (guard pipe) and a concrete rain pad. Wells at gasoline stations, usually <br /> being in high-traffic areas, are typically finished with a flush-mount, curb box and <br /> protective 8" diameter steel inspection plate rather than a stick-up riser. The curb box is <br /> usually easily removed from around the flush-mount well before pulling or over-drilling. <br /> In the case of stick-up wells, the riser pipe may be bonded to the guard pipe and rain <br /> SL-SOP Well Decommissioning EA, Inc. <br /> Battle Mountain Resources, Inc. Pa a 11 of 21 Ma 6, 2019 <br />