2004-02-24_REVISION - M1977153 (4)

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Geotechnical Data Technical Memorandum Hazeltine -Road Runners Rest II Gravel Pit Lining Project December 2000 3.0 FIELD EXPLORATION PROGRAM 3.1 General The fie]d exploration program consisted of two phases of drilling exploration borings, three phases of test pit excavation, and one phase of stockpile and tailings pond sampling. Denver Water provided a base topographic map of the Project site and surveyed the horizontal coordinates and elevations of the borings and the Phase Three test pits (see Section 3.3). The locations and elevations of the Phase One and Phase Two test pits and the samples collected from the Howe-Haller stockpile and tailings ponds at the Hazeltine and Howe-Haller Pits were estimated bypacing from existing physical features and interpolation of contour lines on the base topographic map. The locations of the test pits, test borings, and stockpiles are shown on Figure 3.1. 3.2 Borings The purposes for the subsurface exploration borings were to determine the subsurface stratigraphy; observe and evaluate overburden and rock mass properties (weathering and fracturing); perform packer permeability tests in the bedrock; identify the level of groundwater; and install open-standpipe piezometers in the completed borings. The first phase of drilling consisted of four exploration borings (B-101 through B-104) around the perimeter of the Hazeltine Pit. Phase 1 borings were drilled between June 8, and June I5, 1998. The second phase of drilling consisted of sixteen exploration borings (B-105 through B- 120), which were located around the east, southeast, and west sides of the Hazeltine Pit and the west, north, and east sides of the Road Runners Rest II Pit. The second phase of borings was drilled between September 9 and October 19, 1998. Terra Drilling Services, Inc., Lafayette, Colorado, drilled the exploration borings for both phases under subcontract to GEI. GEI coordinated, observed, and logged the borings. Except for Boring B-119, borings were generally evenly spaced around the perimeter of the pit. Boring B-119 was located to evaluate a deep bedrock channel that trends northeast to southwest across the site. Figure 3.1 shows the approximate locations of the borings and Table 3.1 summarizes the subsurface exploration program. 98_15~gco ,m,,.,n 3_1 ~ Gl:l Consultants, Inc.