COMPLIANCE INFO_1993-2007 - Laserfiche WebLink

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Clayton Group Services A monitoring well that is no longer useful, permanently inactive, or abandoned must be properly destroyed. Such a condition commonly exists after site closure has been obtained or a "no further action" letter has been issued by the site oversight regulatory agency. Wells are abandoned to eliminate a possible avenue for contaminants to enter the subsurface and to prevent possible injury to humans and animals. Monitoring well destruction shall follow California Department of Water Resources Bulletin 74-81, Water Well Standards: State of California and its supplement Bulletin 74- 90, California Well Standards. By reference, these standards are incorporated into these Stand Operating Procedures. Although well abandonment procedures vary, two techniques commonly are used to destroy groundwater monitoring wells: 1) removing all material within the original borehole, including well casing, filter pack, and annular seal; and filling the created hole with appropriate sealing material, and 2) filling the well with impervious material generally a bentonite slurry using pressure grouting, excavating around the well casing to a depth of 5 feet, removing the well casing to this depth, and then emplacing cement to the ground surface. PROCEDURES Destruction by Removing All Material - 1. Obtain the required well abandonment permit. 2. Prepare a "Health and Safety Plan". 3. Review well construction details and conduct a down -hole inspection, generally by measuring well depth to determine if bridging or other interferences are present in the well. If interferences are present, well remediation may be necessary prior to abandonment. To be sure that the entire well can be plugged and properly abandoned. However, destruction by removing all material often may be accomplished even if interferences are present.