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<br /> <br /> <br /> <br /> <br />C-PIT Hydrogeologic Investigations <br />Technical Revision No. B <br />2: Site Analysis and Field Activities Mining Permit M-1977-208 <br />September 15, 1989 Air Photo <br />The relocated portion of the Boulder Feeder Canal west of C-Pit is now completed and operational, with <br />water visibly flowing. The old Canal channel west of C-Pit is visible and now abandoned, and the area <br />between the old Canal alignment and the Swede ditch remains substantially undisturbed. The progress of <br />mining in C-Pit does not appear to have significantly increased since late 1986, although impounded water <br />may be present along the eastern highwall of C-Pit. Impounded water is also visible along the highwall <br />formed by excavation/mining in the area between the old and new Canal south of the access bridge to B-Pit. <br />This is the same area where a pond now exists southwest of C-Pit, in an area adjacent to what is referred to in <br />the CEMEX mining permit file as D-Pit (see Figure 2). <br />May 10, 1993 Air Photo <br />Ongoing mining activity has now obGtetated the former alignment of the Boulder Feeder Canal. In contrast <br />' to the September 1989 photo, the area between the Swede Ditch and the new Canal alignment appears to be <br />mined and partially reclaimed, with some ponding of water in low-lying areas. The progress of mining in C- <br />Pit does not appear to have significantly increased since the pnox photo (September 1989). <br />^ June 1996 <br />Other photos on display in the CEMEX Lyons Plant office conEtxm that the mining activities in C-Pit and <br />west of C-Pit continued beyond 1993. A photo dated June 1996 shows active mining in the eastem portion <br />of C-Pit, with goaded water visible along the north end of the eastern highwall. The Feeder Canal is running <br />full at this time, and the area between the Swede Ditch and north end of the relocated Feeder Canal where it <br />ties into the original canal alignment is being Etlled with an estimated 20-foot thick lift of material. The mined <br />area southwest of C-Pit also holds water. This is the location of the present day southwest pond (a remnant <br />of mining in D-pit) shown on Figure 2. NCWCD drawings show that a 54inch reinforced concrete pipe <br />(RCP) culvert feeds this pond by routing runoff water from the reclaimed B-Pit to the west under the Canal. <br />This culvert has been located and confirmed in the field (see discussion in Section 2.2.3). <br />2.2 Surface Water Ditches/Canals <br />2.2.1 Operational Features <br />Three surface water structures route water around the Site: the Boulder Feeder Canal and the Swede Ditch to <br />the west of C-Pit, and the Highland Ditch northeast of C-Pit. See Figures 1 and 2. <br />2.2.1.1 Boulder Feeder Canal <br />The Boulder Feeder Canal is operated by the NCWCD and carries a maximum design flow of 200 cubic feet <br />per second (c Es) during the irrigation season. The 2007 irrigation season started out wetter than the long term <br />average, and therefore NCWCD kept the flow rate below 10 cfs from mid-Apri12007 until late-May. Fmm <br />late-May until mid June, flows remained under 20 cfs, until they increased up to their present range of 80 to <br />130 cfs (average daily Elow rate). NCWCD staff have indicated that they believe the peak flows for the 2007 <br />irrigation season will range from 160 to 170 cfs. Imgation flow will cease around October 1. <br />Refer to Section 2.1 for a discussion of the history of the relocation of the Boulder Feeder Canal to its <br />present location west of C-Pit. <br />2-3 <br />Use of commis on Ihis sheet is subled to the Iimitaiions spectlied at the end of this tlocument. <br />\\BCDEN02\pm~eclslDatatGENlCemexlTR-81Reponing\CEMEX Report 0831-07.doc <br />