2009-03-04_REPORT - M1973021 - Laserfiche WebLink

Home Browse Search

1.0 INTRODUCTION This report summarizes geotechnical observations made January 19, 2009 on the active and inactive mine areas at the Morrison Quarry operated by Aggregate Industries (AI). This report supplements the "2008 Notice of Intent to Continue Mining Operations / Annual Report" for the Morrison Quarry. Joint and foliation attitudes were mapped for areas mined in 2008 in order to characterize the rock mass exposed. Other features affecting stability such as shear zones, faults, or failure surfaces, were described and mapped as well. The field data collected • was used to make recommendations regarding the configuration of future mine slopes. This d over addendum, therefore, provides information required by Permit Amendment #5 (carrie from Permit Amendment #3 and #4) to Mining Permit M-1973-021. 1.1 Observational Method Previous Permit Amendments describe the "Observational Method", which is a process of • observing highwall development to evaluate the rock mass stability and recommend slope angles. The default slope configuration at the quarry is conservatively defined at 1 H:1 V • highwall height to bench width. Ongoing observation of the rock mass is used to alter the default slope configuration when necessary for safety or desirable for production. Annual • Geotechnical Addendums as well as Technical Revisions to the Permit convey the information gathered using the Observational Method to the Colorado Division of Reclamation, Mining, • and Safety (DRMS) for review. 1.2 Site Description The Morrison Quarry is located west of Colorado Highway 8 approximately 1/2 mile north of U.S. Highway 285 in Jefferson County, Colorado as shown on Figure 1. The site is situated in • the Front Range foothills west of the Dakota hogback. Mount Falcon Open Space Park is located west of the site. The Quarry currently consists of a north mined area, the North Quarry, in which active mining no longer occurs, a central mined area, the Central Quarry, in which active mining no longer occurs, and a south mined area, the South Quarry, where active • mining continued in 2008. The North Quarry has been mined to an approximate elevation of h 6220 feet above Mean Sea Level (MSL) utilizing highwalls and benches. Activity in the Nort Quarry included the construction of several staff gauges by the Town of Morrison in anticipation of the future North Quarry reservoir. The Central Quarry has been mined to an approximate elevation of 6330 feet above MSL utilizing highwalls and benches and also • contains a stabilized slope located in the northeast section of the quarry. A haul road on the east side of the Central Quarry was completed in 2008. The South Quarry has been mined to an approximate elevation of 6760 feet above MSL utilizing highwalls and benches. Other activity • in the South Quarry included construction of haul roads. 2.0 2008 MINING SUMMARY • 2.1 North Ouarry Mining in the North Quarry was completed as of December, 2007. Activity in the North Quarry has been limited to construction of future reservoir appurtenances. As such, no major • • -1- Morrison Quarry Annual Report 2008 February 2009 • FA3919_038\Annual_Report_2008\Geotech_Report _2008\Annual_Report_2008_Geotech.doc • •