2021-03-05_REVISION - M1977141 - Laserfiche WebLink

Home Browse Search

Lyons Quarry �� 112d Reclamation Permit Operations Technical Revision miscellaneous surface debris were removed from the floodplain area by Aggregate Industries; however, several areas impacted by the displacement of stockpiled site materials remain. In response to the 2013 flooding, Boulder County has initiated development of restoration plans for the 3.2 mile stretch of South St. Wain Creek, from the forest service boundary in the canyon to the Old Saint Wain Bridge off Highway 7. These restoration plans are currently at the 30% Design phase and include the floodplain area located between South St. Vrain Creek and the mined high walls at Lyons Quarry. Reclamation of this floodplain area (Area 2) by Aggregate Industries is addressed in Technical Revision #4 which was approved by DRMS in December 2020. 2 Project Location and Description 2.1 Location Lyons Quarry is located southwest of Lyons, Colorado in Boulder County. Attachment A - Figure 1, shows the Lyons Quarry site just south of South St. Wain Creek, along Colorado State Highway 7 in Sections 25 and 26 of Township 3 North, Range 71 West of the 6th Principle Meridian. 2.2 Recent Flooding The floods in September 2013 changed the low-lying areas of the Lyons Quarry as up to 17 inches of rain fell over a three-day span raising the levels of the South St. Wain Creek to 100 and 500-year floodplains (Boulder County's average annual precipitation is 18 inches by comparison). The flooding washed away the Site access bridge that crossed South St. Wain Creek from Highway 7. Attachment A - Figure 2 and Figure 3, display the pre-and post-flood conditions of the site as aerial images from October 7, 2012 and October 6, 2013, respectively. The extent of the flood destruction and change in creek alignment especially at the east end of the site is shown on these images. Boulder County Parks and Open Space, the current property owner, contracted a design group to develop restoration plans for the 3.2 mile stretch of South St. Wain Creek, from the Forest Service boundary in the canyon to the Old Saint Wain Bridge off Highway 7. These restoration plans include the floodplain area located between South St. Wain Creek and the mined high walls at Lyons Quarry. Restoration of South St. Wain Creek downstream of the site was completed in 2017. During this work, approximately 29,000 cubic yards (CY) of cobble material from impacted reaches of South St. Wain Creek downstream of the site were allowed to be disposed of within Quarry#2 of the Lyons Quarry as document in Technical Revision #3. This saved the restoration project both time and transportation costs. The preliminary designs for the floodplain area adjacent to the Quarry call for realignment of the creek. This realignment will be a consideration for the reclamation design of both the floodplain and quarry area. 2.3 Lyons Quarry Lyons Quarry is located southwest of Lyons, Colorado approximately 10 miles north of Boulder, Colorado. According to records from the 2002 permit Technical Revision #1, the total reclamation area (Project) covers 71 acres (55 acres have been disturbed) of the approximately 266-acre March 2021 1 3