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Well Abandonment Work Plan -3- 16 December 1991 <br /> DDRW, Tracy <br /> propose sampling of the monitor well (LM-60) to be abandoned. Ground water <br /> samples should be collected from LM-60, if possible, and analyzed for <br /> halogenated hydrocarbons (Method 601) to document what the concentration of <br /> VOCs may be in the well sample prior to abandonment. The last samples to <br /> be collected from this well were in 1988. <br /> Page 3-4. Discrete soil samples are to be collected from the two supply wells slated <br /> for abandonment. The need for soil samples appears unnecessary. Our <br /> specific comments can be discussed at the next Project Manager's Meeting. <br /> Page 4-2. The Plan indicates that the drill cuttings will be containerized and <br /> samples collected and analyzed to determine proper disposal of the <br /> materials. The Plan should be clarified as to whether or not the drilling <br /> muds, that are determined to have nor-detectable concentrations of VOCs, <br /> will be disposed of on-site as has been done in the post. <br /> Page 4-3. The Plan proposes sampling of the sand with the casings of the two supply <br /> wells to indicate potential contamination within the casings. Proposals <br /> for sampling of these cuttings may not be appropriate because of the <br /> drilling method. If the samples are air lifted, as proposed in the Plan, <br /> the samples will not be representative of VOC concentrations down-hale. <br /> Sampling and analyses for soils should be discussed at the next Project <br /> Manager's Meeting. <br /> Page 4-4. The ground water samples from the supply wells are to be collected without <br /> purging the wells. The reason presented in the Plan for not purging the <br /> wells is that the well casing may collapse or it may be damaged. It is <br /> unclear how purging will collapse the casing if drilling fluids are to be <br /> added to prevent collapse (page 4-2) . Furthermore, it is unclear how <br /> representative ground water samples can be collected from the supply wells <br /> if the well is loaded with drilling fluids and the well will not be purged. <br /> These issues need to clarified. <br /> Page 4-5. Section 4.3.1 .7 includes the list of analytes for the ground water samples. <br /> If representative ground water samples can be obtained, the primary <br /> analyses should be for halogenated hydrocarbons (Method 601) and minerals. <br /> The following comments should be considered. <br /> 1 . Not all of the heavy metals listed in Section 66699 of Title 22 are <br /> included in the list. Barium, cobalt, molybdenum and vanadium should <br /> be included for analyses to completely analyze for Title 22 metals. <br /> 2. If barium drilling muds are added during drilling, the analytical <br /> results for barium and sulfate may be highly elevated. <br /> 3. Silica should be added to the list of general minerals. Because Well 1 <br /> may be drawing water from both the Upper and Lower Tulare Formations, <br /> the analytical results for silica may help to differentiate the waters <br /> from the two formations using discrete sampling. <br /> 4. Analyses for potassium does not need to be performed using AA. <br /> Analyses for potassium may be performed using other methods, such as <br />