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Home Office Well Monitoring Program Interim Report <br />1.0 Introduction <br />1.1 Scope and Purpose <br />`~ This report presents the results of a well monitoring program instituted by Lafarge West, Inc., <br />~ with the approval of the State of Colorado Division of Minerals and Geology (DMG) and Larimer <br />~ County. The monitoring program was developed in response to concerns about groundwater <br />~ levels relative to an approved gravel mining operation at the North Taft Hill Expansion Site on <br />LCR 19 north of Fort Collins, Colorado. The program seeks to establish baseline groundwater <br />is levels in vicinity of the site prior to start of dewatering activities associated with the mining <br />e operation. This baseline will be compared to data collected during the life of the operation to <br />determine if any significant changes to groundwater levels have occurred. Statistical analysis is <br />A performed as part of the program to objectively evaluate numerical data and isolate changes <br />S associated with mining activities from those associated with seasonal fluctuations and river <br />~ flows. The result of this analysis is compared to qualitative information goals to establish <br />whether any mitigation by Lafarge West is necessary to offset negative impacts to groundwater <br />S due to mining activities. <br />e <br />~ 1.2 Project Location and Description <br />~ Eleven monitoring wells surrounding the North Taft Hill Expansion site at varying distances <br />~ have been established for taking measurements associated with the monitoring program. <br />These wells have either been modified for this use or driven specifically for the purpose, <br />~ generally consisting of 2" PVC tube with a perforated end piece. Figure 1 is a map showing <br />b location of these eleven wells. <br />Measurements have been taken for groundwater elevation, conductivity (a measure of <br />dissolved solids) and pH (a measure of acidity) at each well. Groundwater elevation is <br />measured monthly, conductivity and pH are measured quarterly. Results are reported annually <br />except in the case of a significant change. <br />~ 1.3 Information goals <br />The primary goal of the monitoring program is to determine, within a certain confidence level, <br />what the condition was before mining begins and what it is like after mining has commenced, <br />and whether the difference is significant. This has two ramifications. The first is the ability of <br />neighbors to legally use groundwater at the same rate and quality as they had prior to the start <br />of mining. The second is expressed by DMG regulations requiring the operator to minimize, <br />"disturbances to the prevailing hydrologic balance of the affected land and of the surrounding <br />area and to the quality and quantity of water in surface and groundwater systems, both during <br />and after the mining operation and during reclamation." <br />To determine whether either of these two conditions has been violated requires a combined effort <br />of qualitative and quantitative approaches. Statistical analysis can determine whether a significant <br />change has taken place. Reporting from well owners regarding ability to pump at legally <br />mandated rates and quality provide an estimate of the impacts of any potential changes on <br />TST~ ANC. CONSVLTING ENGINEERS <br />Page 1 <br />