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Final April 2009 <br />Groundwater <br />ARCADIS Monitoring Report <br />Florence, California <br />,1. <br />2.2 Field Observations <br />At monitoring well MW-7, the water level probe was covered in sediment when it was <br />removed, indicating that sediment had accumulated in the bottom of the well. In <br />addition, the well had a sulfur-like odor immediately after opening, but as purging of the <br />well began, the odor subsided. <br />At monitoring wells MW-7 and MW-12, a disposable bailer (3-inch bailer for MW-7 and <br />1-inch bailer for MW-12) was used to purge three well volumes. The field water quality <br />parameters including temperature, pH and conductivity were stable (i.e., less than a 10 <br />percent change between readings) after three well volumes and one sample was <br />collected from each well using the disposable bailer. Samples were placed directly into <br />laboratory-supplied containers and kept on ice in a cooler. Copies of the groundwater <br />sampling forms are included in Appendix C. <br />MW-13 was purged using both a peristaltic pump and 1-inch disposable bailer. Seven <br />well volumes were purged from MW-13 to develop the well and stabilize the field <br />parameters. A copy of the groundwater sampling form is included in Appendix C. The <br />purging method consisted of alternating between bailing to bring fines in from the well <br />screen (and set up the filter pack) and pumping using low-flow techniques (i.e., flow <br />was kept between 300 and 500 milliliters per minute) to remove the fines from the <br />water column. One sample was then collected using a peristaltic pump with clean <br />disposable Teflon tubing and placed directly into laboratory-supplied containers. The <br />sample was subsequently placed in a cooler with ice. <br />r <br />r <br />cldocuments and settingMstobgyMy documents\holcim\025911978_holcimreg version_final.docx <br />6