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INTRODUCTION <br /> This report summarizes construction observations and results of the on-site and laboratory quality <br /> assurance testing at the Koenig Pit slurry wall. Information contained within this report was collected <br /> in conjunction with the construction related engineering services that were provided by Rocky <br /> Mountain Consultants, Inc. (RMC) throughout the slurry wall construction. <br /> i� Construction began on the slurry wall lining project at the Koenig Pit in March, 1999, and consisted of <br /> r- <br /> lining a working gravel pit with approximately 4,850 feet of slurry wall. The goal of the slurry wall <br /> liner is to minimize hydraulic interaction between the pond storage area and the surrounding <br /> alluvium. The reduction in hydraulic interaction will aid mining efficiency in two ways: 1) by <br /> reducing dewatering requirements during mining operations, and 2) by reducing drawdown effects on <br /> neighboring wells. Upon completion of the mining activities, the final goal of the slurry wall <br /> construction is to surround the reclaimed pit and provide a low permeability liner for a below grade <br /> water storage reservoir. <br /> The slurry wall was constructed using a design/build approach. The scope of our work during <br /> construction included on-site quality control testing and observation of the slurry wall construction. <br /> The scope of our work did not include groundwater monitoring or reservoir design. Hall-Irwin <br /> ' Construction supplied labor, equipment, and materials to construct the slurry wall. The work was <br /> performed under a contract with the Central Colorado Water Conservancy District (CCWCD). <br /> CCWCD will make use of the reservoir storage to supplement their existing water delivery/storage <br /> system. <br /> PROTECT DESCRIPTION <br /> ( The site is currently being mined by Weld County and is located in the southeast corner of Section 13, <br /> Township 2 North, Range 67 West of the 6th Principal Meridian in Weld County, Colorado as shown <br /> on Figure 1. More particularly described, the Koenig Pit property consists of approximately 43 acres <br /> located southwest of the intersection of Weld County Roads 20 and 25. <br /> The site is located approximately 23 miles east of the foothills of the Colorado Front Range on the <br /> western flank of the Denver Structural Basin. The basin is an asymmetrical downwarp of sedimentary <br /> strata that dips eastward off of the Pre-Cambrian metamorphic and igneous rocks which make-up the <br /> core of the Front Range. In the project area, the sedimentary beds generally dip gently east- <br /> southeasterly toward the axis of the basin which lies east of the site. The sedimentary strata beneath <br /> the site are thousands of feet thick. <br /> -1- <br />