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 3.2.4 Observation Wells , Groundwater observation wells, or piezometers, were installed in seven of the borings , upon completion of drilling and testing. The piezometers were installed by Terra Drilling Services, Inc. under supervision of GEI's Field Engineer. Except for the piezometer in Boring B-101, dual-level piezometers, which allow the groundwater level to be measured ' independently at two depth intervals were installed. Two individual single-level piezometers, which together provide data similar to one dual-level piezometer, were ' installed at Boring B-101 because of complications in installing adual-level piezometer at this location. The seven borings with piezometers and the screened interval depths for each piezometer is presented in Table 3.1. Observation well logs are provided in ' Appendix C. The observation wells were installed in accordance with the rules and regulations of the , Colorado State Board of Examiners of Water Well Construction and Pump Installation Contractors. Well permits were filed with the State for each observation well installed. At a future date when the observation wells are abandoned, the owner of the wells, , Denver Water, will be required to submit State well abandonment permits. 3.3 Test Pits , Phase One of the test pit excavation program was conducted to evaluate material properties and quantities of stockpiled materials at the Hazeltine site and to collect representative soil samples for laboratory testing. Three test pits, identified as TP-1 through TP-3, were excavated in the south stockpile area, and four test pjts, identified as TP-4 through TP-7, were excavated in the , west stockpile area. Test pits were generally spaced evenly across the top of the stockpile areas. The south and west stockpiled areas and the locations of the test pits are shown on Figure 3.1. , Phase Two of test pits was performed to evaluate the subsurface bedrock stratigraphy and jointing and fracturing in the bedrock at the pit bottom near the toe of the pit side slopes. Four test pits were excavated on the floor of the Hazeltine Pit. Three pits, identified as TT-3 through ' TT-5, were excavated along the toe of the east pit slope, and one, identified as TT-2, was excavated along the toe of the south slope at the approximate locations shown on Figure 3.1. Information on bedrock stratigraphy and bedrock joints could not be obtained, because the alluvial soils were much thicker than anticipated and groundwater in the soils caused trench instability. Phase Three was performed to identify the location of the interface between natural soils and clayey backfill soils in the berm between the Howe-Haller Pit and the Hazeltine Pit. These eight GEI Consultants, lnc. 3_4 vs_isero m.,.ya