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M CDIM Standard Operating Procedure 4.1 Soil Vapor Sampling "°'"""'"' Rev.1 6/30/2022 personal protective equipment (as specified in the project work plans) must be worn by all personnel involved with the task to limit personal exposure. 3.3.8 Well Deconstruction When all desired samples have been collected, temporary wells are to be decommissioned with concurrence from the California Well Standards (Bulletin 74-90) along with any local requirements. The well closure process should prevent the well and associated borehole from becoming a conduit for escaping hazardous gas, or for contaminants entering the soil and/or groundwater. When decommissioning vapor wells with tubing, the following decommissioning steps should be followed (DTSC, 2015): • Excavate the borehole down to approximately three feet below grade, exposing the upper portion of the tubing. • Either cut the tubing near the bottom of the excavated hole or pull the tubing out of the ground by hand, removing as much tubing as possible. • If tubing is still visible in the hole upon removal by hand, cut the tubing near the bottom of the hole, then insert' sealant, such as powdered bentonite grout, or silicone caulk, into the exposed tubing, filling it as much as possible; • Fill the open hole with cement grout to within one foot of the surface grade; • Fill the last foot of the hole with compacted native material; and • Restore pavement and vegetation to original conditions, if needed. When decommissioning vapor wells that are constructed with ridged casting, wells can be overdrilled or cement grouted in place pursuant to local requirement. Once the well material is removed, the borehole should be filled to-surface with cement grout. 4 RECORDS Records generated while implementing this SOP will be controlled and maintained by the PM in the appropriate Dropbox data folder. Records will mainly consist of data documented in logbooks or on field data sheets. At a minimum, the following data is recorded: • Name of the sampler • Sample ID number • Sample location • Sample description • Date and time of sample collection • Approximate quantity of sample collected • Type of analysis to be performed 3 Inserting sealant may be accomplished by using a peristaltic pump or large syringe. Sealant must be free of lumps to freely pass down the tubing. 8