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BRIERLEY <br />ASSOCIATES <br />Creating Space Underground <br />April 1, 2015 <br />File No.: 514104 -000 <br />Asphalt Paving Co. <br />14802 W 44th Ave <br />Golden, CO 80403 <br />Attention: M.L. Richardson <br />Director of Strategy and Sustainable Development <br />Subject: Summary of Observed Conditions during Drilling <br />Ralston Quarry <br />Golden, Colorado <br />Ladies and Gentlemen: <br />Brierley Associates (Brierley) has conducted subsurface geotechnical explorations at Asphalt <br />Paving Co. (APC's) rock quarry located at 6569 Highway 93, just west of the intersection with <br />West 64th Parkway, in Golden, Colorado. This letter presents a summary of the water <br />conditions encountered. No groundwater was observed, all water observed in boreholes was <br />either drill fluid, flush water, or from local surface water. <br />Observed Conditions during Drilling <br />Brierley performed two phases of subsurface investigations at the Ralston Quarry, borings LH -1 <br />and LH -2 were drilled in early 2011 and borings BA -3 through BA -81B were drilled in the spring <br />of 2013. The boring locations are illustrated on Figure 1, attached. <br />During drilling, measurements of depth to groundwater were not feasible due to the use of drill <br />fluids (bentonite mud) for coring the rock. These drill fluids were flushed from the boreholes with <br />fresh water (supplied from a water truck) prior to monitoring well installation or packer testing. <br />Temporary monitoring wells were installed at borings BA -4 and BA -6, and packer tests were <br />performed on borings LH -1, LH -2, BA -4, and BA -81B. No water level readings have been <br />collected from the monitoring wells after the drilling program was completed in 2013. <br />Water measurements were taken periodically in the boreholes still open after drilling was <br />completed; periodic measurements during the remainder of the drilling program reflect the levels <br />of drill fluid or flushed water after drilling, and do not reflect groundwater conditions at the site. <br />Measurements of flushed water or drill fluids remained between 6 ft below ground surface (bgs) <br />and 9 ft bgs in borings BA -7, BA -7A, BA -8, BA -8A, and BA -813 and monitoring well BA -6. The <br />relatively small degree of water level fluctuation indicates little water loss into the formation. <br />Water was observed seeping out of the top of boring BA -3 and monitoring well BA -4 after drilling <br />was completed. These two borings are located at the north end of the quarry where nearby <br />mine slopes and broad benches exist at higher elevations. Observations from the Brierley staff <br />on site noted increased flow in boring BA -3 corresponding with snowmelt or rain events. <br />990 S. Broadway, Ste. 222, Denver, CO 80209 1303.703.1405 1 www.BrierleyAssociates.com <br />