Miller Reservoir and Dam is a 43-ft-high (13-m-high), 5,000-ft-long (1,524-m-long) dam located along the South Platte River north of Denver, CO. The reservoir is located at the site of a previous gravel mine. The capacity of the original gravel pit reservoir was about 800 acre-feet (986,800 m3). By constructing a perimeter embankment and soil-bentonite cutoff wall and mining material within the limits of the reservoir, the storage was increased to over 2,000 acre-feet (2,467,000 m3). This additional storage is an integral part of the water management system of Denver Water, which services 1.3 million customers and is Colorado's oldest and largest water supplier. Because of site constraints and property boundary limitations, the seepage barrier for the dam foundation included the combination of about 6,600 ft (2,012 m) of soil-bentonite cutoff wall with about 1,400 ft (427 m) of core trench extending into bedrock. The embankment consisted of three different typical dam sections that made use of available onsite materials for construction. Four distinct methods to connect the clay core of the embankment with the different seepage-control measures were designed and incorporated into the project. Vertical connections between the clay core, soil-bentonite cutoff wall, and bedrock were also designed and installed adjacent to the outlet works tower. This paper will present the different types of seepage control, incorporation of the embankment internal zoning with the seepage-control methods, and material utilization for dams with multiple seepage barriers.

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