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C-PIT Hydrogeologic Investigations Technical Revision No. 8 2: Site Analysis and Field Activities Mining Permit M-1977-208 occurring in the access road ditch line west of the Canal and south of the B-Pit access bridge. This seepage was routed to the 54-inch RCP discussed below in Section 2.2.3.2. Inspection of the C-Pit highwall on August 22 revealed more seepage than had been observed on July 19. Seepage into C-Pit was evident at the extreme southern comer of the pit, and at multiple locations along the west side. Water was observed dripping from fractures in exposed portions of the Fort Hays Limestone, with sufficient flow volume to accumulate and flow along the floor of the pit, creating a shallow pool of standing water on the west side of C-Pit along the highwall. The previously noted vegetation on and along the base of the highwall continues to thrive. See Photo No. 14 in Appendix C. 2.2.3.1 Fort Hays LimestonelBoulder Feeder Canal An unmined portion of the Fort Hays Limestone is currently visible in the west wall of the Boulder Feeder Canal at the northern end of the reach west of C-Pit immediately east of piezometer P-003. See Figure 2 and Photo No. 4 in Appendix C. The bottom grade of the Canal and the limestone bed converge as the Canal drops toward the south, indicating that at least in this northern area a block of residual limestone remains. Presumably, the complete [Wining of all of the limestone in this azea was limited by the presence of the original Feeder Canal as it turns to the north and west away from C-Pit. The likely location of where the relocated Canal converges with and ties into the original canal alignment is just north of the northernmost Brown and Caldwell flow gauging location, as shown on Figure 2. The eastern wall of the Canal at this location appears to transition from a fill slope into the solid bedrock wall of the original canal alignment, as shown by Photos No. 4 and 5 in Appendix C. The remnants of shotcrete, now mostly eroded away, are still visible along the bottom of the fill that makes up the east wall in this location, showing the intent to minimize seepage losses. This is the location of the "earth plug" that was designed to seal off the relocated canal from the original alignment, as shown on the 1981 Plan and Profile drawing in Appendix B. 2.2.3.2 B-Pit Drainage and Canal Seepage to D-Pit Pond, Southwest of C-Pit Field inspection on May 3, 2007 confirmed the presence of a 54-inch diameter reinforced concrete pipe (RCP) routing upland reclaimed B-Pit surface water drainage under the Boulder Feeder Canal into the pond located southwest of C-Pit. The 1981 design drawings for the Boulder Feeder Canal Relocation Project indicate that this culvert was designed to receive the drainage from the full extent (north-south) of the east side of the reclaimed B-Pit area (approximately 2700 feet in length). Topographic mapping does not exist for the reclaimed area west of the Canal, but the tributary area to this culvert is estimated to be approximately 25 acres. Field inspections in May and again in August indicated the presence of flowing water and water-born debris at the inlet structure (west end) to this culvert, as well as standing water at the discharge end adjacent to the pond. See Photos No. 15 to 19 in Appendix C. Most notably, the August 22, 2007 inspection indicated that Canal seepage water was welling up in the ditch line on the west side of the canal in the fill section south of the B-Pit bridge and entering the culvert (see Figure 2 and Photo 16). However, there was no evidence of similar seepage through the east face of the embankment holding the Feeder Canal. Comparison of the photos taken of the Southwest pond on May 3, 2007 and August 22, 2007 confirms that ' the water surface elevation of the pond has risen several feet during the summer irrigation season. See Photos No. 18 and 19 in Appendix C. This is likely pnmarily due to seepage from the Boulder Feeder Canal entering the pond as surface water via the 54-inch culvert, or as subsurface flow through the embankment that holds the Canal in this area. ' 2-6 Use of contents on this sheep is sublet[ to the hmeaeons specdied at the end of this document. \`,BCDENODpmjectslDatalGENlCemex\TR-E1Reporeng\CEMEX Repor10B-31-07 tlw