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~*n Public Notice US Army Corps DENVER Public Notice Number: 199475260 of Engineers OFFICE Date: March 13, 1996 Sacramento District Comments Due: AKlril 15, 1996 1325 J Street Sacramento, CA 95814-2922 In reply, please refer to the Public; Notice Number TO WHOM IT MAY CONCERN: SUBJECT: Application for a Department of the Army permit under authority of ,section 404 of the Clean Water Act (CWA) and for water quality certification under Sectiim 401 of the CWA to continue fill and excavation activities associated with mining approximately 18,800 cubic yards of alluvium annually from the Thomas Pit located on the Animas River, as shown in the attached drawings. APPLICANT: Mountain Redi Mix (previously Animas Aggregates, Incorporated) Attn: ~ Mr. David King 34606 U.S. Highway 550 Post Office Box 1447 Durango, Colorado 81302 LOCATION: The Thomas Pit is located approximately 11 miles north of the Ci~ry of Durango in the Animas River and along the west riverbank within Sections 25 and 36, Township 37 North, Range 9 West, La Plata County, Colorado. PURPOSE: To continue extracting sand and gravel for commercial sale. PROJECT DESCRIPTION: The applicant proposes to continue annual extraction of sand and gravel from the Animas River. A large dike feature measuring 1,400-feet long by 20- feet high by 90-feet wide is located in the river in the lower southern half of the lit boundary area and acts as the east boundary line. This dike feature has been in place for several years as evidenced by cottonwood trees growing on the side slopes. West of this lazge dike is a defined extraction azea referred to as a "harvest pit or dredge basin." where excavation occurs, normally at the upstream portion. During low flow periods, between the months of September to April, river flow is blocked at the prt's entrance by the placement of approximately 450 cubic yards of fill material comprised of concrete blocks, boulders, and alluvium. Approximately 18,800 cubic yards of sand and gravel is then dredged or removed from the dewatered channel or harvest pit by excavators and front end loaders. The wet alluvial material, ranging in size from 10-inch rock to sand, is placed on the adjacent west bank above the ordinary high water mark of the river. The mined material is processed onsite by a crusher spread to obtain the desired aggregate material sizes. Sand material is washed and the dirty waste water is channeled to a settling pond to prevent direct dischazge and silting into the river. Water is retained in the pond and allowed to percolate down through the ground. Based on this method of handling, a Section 402 discharge permit is not required from the Colorado Department of Public He<~lth and Environment, Water Quality Control Division.