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Groundwater Monitoring and Mitigation Plan for <br />Heit Aggregate Resource Operation-Weld County <br />Aquatic and Wetland Nursery and Coyle Properties <br />locations of three existing wells that we recommend be monitored (labeled "A-C") and the <br />general locations of seven new piezometers. Permission will be needed from the well owners to <br />enable monitoring, and the wells will have to be observed to assess the feasibility of monitoring. <br />The proposed locations for the piezometers should be observed to confirm access and the <br />feasibility of construction. Piezometers will be constructed of small diameter PVC pipe with <br />slots in and neaz groundwater. The top of casing will be sealed with bentonite chips. <br />Attachment A is a detail of the piezometer construction. The minimum recommended depth of <br />piezometers is 10 feet; it may be necessary to go 15 feet at locations where groundwater is <br />deeper. The top of casing of all wells and piezometers used for monitoring will be surveyed. <br />It is recommended that groundwater be measured at least monthly in each well and piezometer <br />for a minimum of one year prior to mining to enable determination of baseline conditions. This <br />will allow for observation of annual fluctuations in groundwater levels and estimation of normal <br />growing and non-growing season groundwater levels. <br />4.0 DATA EVALUATION AND DEFINITION OF "TRIGGER" <br />Pre-mining groundwater data will be evaluated to determine baseline condition with respect to <br />the following at each well/piezometer: <br />1) Average growing and non-growing season water level, and <br />2) Range of growing and non-growing season levels. <br />Precipitation conditions (e.g., average year, dry yeaz) will be considered when analyzing the data. <br />The growing season will be defined as from May 15 through October 1. <br />021-110.030 Wright Water Engineers, Inc. Page 3 <br />' July 2003 <br />