UPRR Valley Subdivision MP 239.83 Bridge Repair Project (Project)

The proposed project will repair pier #6 of the existing bridge at Milepost 239.83 on the Valley Subdivision. An excavator equipped with a vibratory sheet driver will install steel sheet-pile forms a minimum of 6 inches from the perimeter of the existing 8-foot-by-22-foot pier to a minimum depth of 10 feet below the scour line, containing a 9-foot-by-23-foot area. If any standing water remains in depressions adjacent to the pier, a pump will dewater the area contained by the sheet pile, and the contained area will be excavated to create a void. Controlled low-strength material (CLSM) will be pumped into the scour hole in 3-foot-deep layers and allowed to cure before the next layer is poured. CLSM poured between the existing pier and the sheet-pile form will result in 0.0007 acre of new fill. When poured to a depth of 10 feet below the scour line, a volume of approximately 11.5 cubic yards of CLSM will be required. Additionally, two existing abandoned piers and associated sheet-pile cofferdams from a previous bridge, each approximately 12-feet by 24-feet, will be removed from the Cottonwood Creek channel. The structures will be cut 3 feet below the ground line. One of the two abandoned pier structures is below the ordinary high water mark of Cottonwood Creek, and its removal will result in 0.018 acre and 32 cubic yards of temporary impacts. With the staging and work area for the Project, the combined total of temporary impacts will be 0.097 acre. Following construction activities, debris will be removed, temporary work and staging areas will be restored to pre-project contours as necessary, and best management practices will be removed.