2009-08-01_HYDROLOGY - M1981112 - Laserfiche WebLink

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1 1.0 Introduction Builders Aggregate Company, Inc. operates a sand and gravel business on the Builders Aggregate Company and JJ Concrete, LLC properties located at 18825 Colorado Highway 52 in Fort Morgan, Colorado (Figure 1). Builders Aggregate Company has mined gravel from these properties since about 1959 and typically operates seasonally (May through September) with one part-time employee. On June 25, 2008, the U.S. Army Corps of Engineers (Corps) conducted an inspection of the properties (project site) and determined that fill material had been discharged into and excavated from the South Platte River (River) and its adjacent wetlands on both the left (northeast) and right (southwest) banks of the River without a wetland permit from the Corps. Officials from the U.S. Environmental Protection Agency (EPA) visited these properties and on April 16, 2009, issued Builders Aggregate Company, Inc. and JJ Concrete, LLC a Findings of Violation and Administrative Order for Compliance. As illustrated by Figure 2, the two properties are located in the south ½ of the northwest ¼ of Section 31, Township 4 North, and Range 57 West of Morgan County, Colorado. Per the requirement of the Order, a Removal & Restoration Plan and a Habitat Mitigation & Monitoring Proposal, referred to as a Fill Removal & Habitat Restoration & Monitoring Plan, has been developed. Please note, Figures are located in Section 11, Tables are in Section 12, and Photographs are in Section 13. 2.0 Existing Physical Conditions 2.1 Location & Access The two properties are located at 18825 Colorado Highway 52, in Fort Morgan, Colorado (Figure 1). Each of the properties can be accessed via separate roads from two locations on West Beaver Avenue (Figure 3). There is one access road north of the bridge over the River and one south of the bridge. Builders Aggregate Company has an easement with the Western Sugar Company for the south access road. 2.2 Property Boundaries & Streets The approximate 44 acre JJ Concrete property abuts Colorado Highway 52 on the east and extends west to encompass a section of the South Platte River. The rectangular-shaped approximate 39 acre Builders Aggregate Company property is located both west and north of the JJ Concrete property and also encompasses a segment of the South Platte River (Figure 2). 2.3 Structures & Equipment The area northeast of the River (left bank) is characterized by a trailer office building, two metal shop buildings, an abandoned trailer immediately west of the office trailer, and dozens of abandoned and non-operational vehicles and machines currently and formerly used in the sand and gravel operation (See Figure 3 and Photos 1-5). Southwest of the River (right bank) there is an existing mining pond with a floating hydro dredge, a sand and gravel sorter, a tipple, other equipment used in the mining process, and a pile of rock (Photos 6-8). 2.4 South Platte River 2.4.1 Hydrology The hydrology of the River near Fort Morgan is characterized by high spring runoff from mountain snowmelt that typically lasts for several weeks during spring and early summer, and by short duration events of very high magnitude that periodically occur as the result of large rainfall events in tributary watersheds. Diversions to reservoirs and for irrigation and municipal use reduce the