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ARCADIS <br />Executive Summary <br />ARCADIS was retained by Holcim (US) Inc. (Holcim) to conduct annual groundwater <br />sampling of the quarry groundwater monitoring wells at its Portland plant, located in <br />Florence, Colorado. The sampling was performed to fulfill the Colorado Division of <br />Reclamation Mining and Safety (DRMS) requirements, which were triggered by <br />Holcim's disposal of Cement Kiln Dust (CKD) into previously mined sections of the <br />quarry, and the potential for leachate from CKD to adversely impact ambient <br />groundwater quality for existing and potential future uses. <br />Based on a previous DRMS inspection in December 2007 and subsequent discussions <br />with the DRMS following the March 2008 annual groundwater monitoring event, Holcim <br />submitted a revised Groundwater Monitoring Plan (GMP) to the DRMS in November <br />2008. This revision to the GMP proposed the installation of one new monitoring well <br />(MW-13) located hydraulically downgradient of the CKD landfill, annual monitoring of <br />this new well, along with existing wells MW-7 and MW12, and the abandonment of <br />monitoring wells MW-6, MW-8 and MW-10 because they were no longer useable or no <br />longer served a purpose in the monitoring program. The DRMS approved these <br />revisions and requested that Holcim establish compliance standards for the <br />downgradient monitoring wells, which included MW-7 and MW-13. The most recent <br />revision to the GMP, submitted by Holcim in February 2009, proposed compliance <br />standards for MW-7, based on highest historical concentrations detected in this well. <br />The DRMS approved this latest revision to the GMP, with the condition that MW-13 be <br />monitored for five consecutive quarters to provide data for establishing compliance <br />standards. <br />Subsequently, ARCADIS was retained by Holcim to install monitoring well MW-13 and <br />abandon wells MW-6, MW-8 and MW-10 prior to the 2009 annual groundwater <br />monitoring event. MW-13 was installed on April 3, 2009 to a depth of 30 feet below <br />ground surface using air rotary drilling methods. Wells MW-6, MW-8 and MW-10 were <br />abandoned on April 7, 2009 using pressure-grouting methods. <br />The annual groundwater sampling was then performed on April 21, 2009 and included <br />water level measurements at all existing wells and groundwater sampling at wells <br />MW-7, MW-12 and MW-13. In addition, well development of MW-13 was completed <br />prior to groundwater sampling. Groundwater samples collected from the wells were <br />submitted for analysis of metals (arsenic, selenium, aluminum, iron, manganese, <br />magnesium, potassium, sodium and calcium), total dissolved solids (TDS), alkalinity, <br />Final April 2009 <br />Groundwater <br />Monitoring Report <br />Florence, California <br />cAdocuments and settings\stobgy\ ny documents\holclmt025911978_holcimreg version_final.dom