2009-08-01_HYDROLOGY - M1981112 - Laserfiche WebLink

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6 and eliminate the water. Waste material removed from the screens flows back into the pond behind the dredge. The mining process removes approximately 6% of the materials dredged. Thus, as the pond is slowly filled it is correspondingly enlarged. Mined products are stored on-site in various piles by gradation. During storage, the piles of sand and gravel naturally de-water and drain back into the pond. Please note, it takes the hydro dredge one year to make a 180° arc around the outside perimeter of the pond. 2.9 Areas of Alleged Unpermitted Fill 2.9.1 Left Bank In June 2008, Builders Aggregate Company used a track loader and truck to remove sand from the left bank of the River (Figure 5). The excavated and unsorted material was used as fill material to create level surfaces on the northeast corner of the property in order to stockpile their sand and gravel products. They created a sandy ramp that extended into the River below the OHWL and excavated and stockpiled sand. Photo 9 illustrates the graded condition of the left bank on May 11, 2009 following the excavation in June 2008. Mr. Terry McKee of the Corps visited the project site on June 25, 2008 and informed Builders Aggregate Company that they needed a permit from the Corps in order to extract sand from below the OHWL of the River. Photos 10 and 11 illustrate the existing condition of the Left Bank today, following the sand and gravel deposition during periods of high River flows in June 2009. Please note, the stockpiled sand and gravel was removed following the EPA visit on April 16, 2009. In about 2005, Builders Aggregate Company placed fill in the High Flow Channel in order to provide access to the River. This fill impacted 351 square feet of channel and the adjacent sandbar willow wetland (Photo 12). 2.9.2 Right Bank A series of photographs have been prepared to illustrate conditions on the project site from 1963 to 2006. The 1963 aerial photo (Figure 11) was taken four years after sand and gravel mining began in 1959. Please note the gravel mining ponds northeast (left bank) of the River, the mine spoil area, and the undisturbed condition of the property southwest (right bank) of the River. Please also note the flood condition of the River and the sandbar on the left bank. Figure 12 illustrates the properties in 1969, four years after the severe flood of 1965, which had a flow of at least 46,600 cfs. Please note the extensive deposits of sand along the River from the flooding and the absence of mining southwest of the River on the right bank. This photo also illustrates that almost all of the area north of the River has been mined. Figure 13, taken ten years later in 1979, shows that the last remaining unmined area north of the River has been mined and that mining has commenced southwest of the River on the right bank. The eastern end of the area on the right bank has been mined and there is a spoil area, and the mining pond has moved to the south. The mining pond has an outlet to the River. There is also a small area of potential wetland along the River on the right bank north of the mined area. Figure 14 illustrates the project site ten years later in 1989. The mining pond has moved to the south and the spoil area on the north end of the right bank between the River and the property line is much larger. The River now has a braided channel and it has deposited sand along the right bank, which is likely vegetated with sandbar willows. A portion of this sandbar on the right bank could have been a wetland. Figure 15 illustrates the project site and right bank four years later in 1993. The mining pond has moved all the way to the south end of the project site and the spoil piles are much larger and extend all the way to the south end of the property. The area of wetland along the north end of the River on the right bank is small and confined to the edge of the River. The channel of the River is still braided.