2003-09-29_REPORT - M1987049 - Laserfiche WebLink

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September 29, 2003 File No. 00036-002 Division of Minerals & Geology Page 2 of 3 Mining activities at the site occurred within one general area that comprised approximately 9.3 acres that were newly disturbed, and within adjacent areas shown as disturbed during previous years. New disturbance was less than the anticipated 12.4 acres of mining planned for 2003 (see 2002 Annual Report Map) because production was less than anticipated due to market conditions. Reclamation of additional perimeter along the northern site boundary comprised approximately 13.2 acres of new fill slope placement and grading, as well as regarding north of a previously reclaimed area. This work also included approximately 6 to 7 acres of new seeding in the western half of the 13.2 acres of reclaimed area at the northern site boundary. The second area of reclamation during 2003 was an additional 2.2 acres of berm constructed between future water storage Cells No. 1 and No. 2, making the total reclamation acreage for the year 15.4 acres. In addition, mowing and re-seeding to inhibit weeds and promote establishment of reclamation plant species occurred at previously seeded areas, particularly along the eastern site boundary. It is important to note that reclamation is being performed with the anticipation that the City of Brighton (landowner) will construct a slurry wall along the perimeter and some reclamation topsoiling and seeding will likely be disturbed and/or occur after slurry wall construction. Proposed new mining disturbance for the upcoming year will occur as shown on the attached map and it is estimated that this will impact an additional approximately 7.9 acres next year depending upon market demand. Eight (8) piezometers were installed during the previous reporting year. These were generally placed within a tree stand between the pit and the South Platte River in an area of a future City of Brighton Park. These piezometers vary in distance from approximately 50 ft to 400 ft from the mining limits. Two of the piezometers (P-6 and P-7) are closest to the river, but are temporary because they are inside the mining limits within an area projected to be mined during the 2004 report year. Four of the piezometers (P1 through P4) were installed in March 2002 and the remaining four (PS through P8) were installed in August 2002. All the piezometers demonstrated declines in water levels between March and June 2002, and January 2003. Between January 2003 and September 2003 all the piezometers showed a rise in water level despite continued dewatering, and dewatering progressively closer to the piezometer locations, indicating that the decreasing water levels observed in 2002 were more attributable to the drought than to site dewatering. The effects of dewatering can be seen in the data for piezometer P-1 closest to the active mining area, and possibly in piezometer P-2.