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bls. Erica Crosby <br />March 30, 2007 <br />Page 5 <br />to its current alignment. Moreover, if the area immediately east of the Feeder Canal was <br />mined out as has been reported, it is possible that any significant ditch seepage during prior <br />irrigation seasons has percolated through the backfilled area to the top of the underlying <br />shale unit (Carlile Shale), from where it may be moving down dip to the east and recharging <br />C-Pit. An initial inspection of the Feeder Canal has confirmed that there are three locations <br />along the reach of the canal to the west of C-Pit that are candidates for flow measurement. <br />These candidate locations axe located: <br />1) at the outlet of the culvert at the north end of the reach, where the canal starts to <br />turn to the south; <br />2) immediately west of the CEMEX "Patio" and stacker location, at a concrete <br />structure in the canal where CEMEX has previously pumped process water; <br />3) at the south end of the reach at a bridge crossing that provides access from the <br />C-Pit area to B-Pit. <br />This inspection also confirmed that remnants of a "shotcxete" liner axe still visible along <br />this reach of the Feeder Canal, but it is now largely broken and eroded away, thereby <br />allowing water contact with the bedding planes of the shale that makes up the eastern wall <br />of the canal. <br />Task 3.0 Piezometerand Welllnstallations <br />Up to six (6) piezometers and three (3) monitoring wells will be installed near C-Pit to <br />supplement the existing monitoring well CEM-001 and the proposed compliance well to be <br />drilled at the southeastern extent of the CEMEX property near Hygiene Road to the south <br />(see Figures 1 and 2). The table below provides our current estimate of the depths of each <br />piezometex/well, and denotes the geologic units that are to be monitored. Final depths and <br />screen interval placements will be determined in the field. All piezometers and wells will be <br />installed by a qualified drilling company using air hammer and hollow stem auger <br />techniques. Cuttings udll be spread on the adjacent land surface. Each well/piezometex will <br />be completed above ground and furnished with protective steel casings and bollards fox <br />protection. Well casings will be constructed using Schedule 40 PVC at the diameters <br />specified in the table below, with 0.010-inch slotted screens. Silica sand (10-20) will be used <br />as filter pack material and cement/bentonite grout seals will be placed in each of the wells. <br />Wells unll be developed by surge block, bailing, and/or pumping techniques. <br />A survey of the new piezometers and wells will be performed by a qualified surveyor. The <br />surveyed vertical location of the wells will be the top of each casing from which the depth <br />to groundwater will be measured. A referenced survey point will be demarcated with a <br />black mark on the north side of each well casing. Horizontal locations will be measured <br />with an accuracy of 0.1 ft and vertical locations will be measured with an accuracy of 0.03 ft. <br />As summarized in the following table, piezometers P-001, P-002 and P-003 will be located <br />between the Boulder Feeder Canal and the Swede Ditch, and will be completed to the <br />depth of the top of the Carlile Shale that underlies the Foxt Hays Limestone. The limestone <br />has likely been mined out in this area, piezometers P-004 through P-006 are proposed to <br />be placed immediately east of the Swede Ditch and to be completed in the unconsolidated <br />materials overlying bedrock in this area. These piezometers axe intended to help assess <br />potential seepage from the Swede Ditch, which, unlike the Feeder Canal to the west, is <br />believed to be constructed in the surficial, unconsolidated sediments overlying the Smokey <br />Hill Shale that makes up the exposed highwall of C-Pit. <br />-~0594686.doc <br />