INSPEC27955

• Permit No: M1974015
• IBM Index Class Name: Inspection
• Doc Name: MINERALS PROGRAM INSPECTION REPORT
• Inspection Date: 10/22/1999
• Media Type: D
• Archive: No

• (Page 2) •
MINE ID # OR PROSPECTING ID # M-74-O15
INSPECTION DATE 10/22/99 INSPECTOR'S INITIALS ESC
OBSERVATIONS
This was a pre-operation inspection of the Lyons Pit (ROCkin' WP) conducted by Erica Crosby,
Allen Sorenson and Tom Schreiner of the Colorado Division of Minerals and Geology. Michael
Hart of Hart Environmental and Dallas Glasser representing Western Mobile Bculder, Inc. were
present during the inspection. The purpose of this inspection was to clarify issues noted in
the DMG adequacy letter dated September 20, 1999 for the Lyons Pit (ROCkin' WP) permit
amendment.
The Lyons- Rockin' WP Pit is located 2 34 miles east of Lyons, southwest and east of the St.
Vrain River. The permit area currently encompasses 234 acres. On July :, 1999, Western
Mobile Inc. filed a permit amendment to M-74-015. The amendment proposes to increase the
permit area from 234 acres to 891 acres, change the approved reclam+rtion plan from
" agriculture" to "developed water resource" and "wildlife habitat," and address the
concerns noted in the Division's 4/13/99-inspection report.
The inspection focused on issues relating to structures within 200 feet of tkie affected area,
surface water and groundwater hydrology, slurry wall construction and backfi:_ling procedures.
The Division inspected the adjacent Miller Site (Permit No. M-52-034) to ob::erve backfilling
techniques on reclaimed sites performed by Western Mobile Boulder/Lafarge. Pit slopes are
reclaimed to 3h:ly slopes with a mixture of clay material to allow groundwater to slowly
enter the pit. The north east corner of the active Miller Pit is less than 20 feet from the
Foothill Reservoir outlet ditch. The outlet ditch was flowing water, and no seeps were noted
on the pit face. The Division also inspected a relocated irrigation ditch north of the
Miller Pit that was lined with bentonite. The ditch was not flowing during the inspection,
but the operator stated that no seeps have been observed, The operator st~.ted that similar
methods will be used to backfill the Lyons Pit and seal any irrigation channels that may be
relocated as a result of the mining operation.
The surface water storage reservoir on the Lyons site was also inspected. ;a slurry wall has
been constructed around the entire pond to capture surface water and prevent groundwater from
entering the pond. The slurry wall was constructed using a mixture of bentonite and fill
keyed into bedrock. The reservoir was approved by the Division of Water F.esources, Office
of the State Engineer. The methods used to construct this slurry wall will oe similar to the
proposed slurry wall in the Amendment Application.
The Division focused on a number of structures within 200 feet of the affected area which
include the Foothill Reservoir located south of Hygiene Road, the Foothill. Reservoir inlet
and outlet ditches, a gas pipeline that leads to Southdown and overhead utility lines. The
operator agreed to remain 200 feet away from the toe of the Foothills Reservoir dam. The gas
line may be within 200 feet of the affected land, but will remain at a di s'=ance 3 times the
depth of the pit (ratio of 3h:lv). The operator will also need to fie13 locate all gas
utility lines within the surrounding area. The operator proposes to install a conveyor
structure over the Southdown access road and below the utility lines. The operator will need
a letter from Public Servite Company prior to installation of the conveyor structure. The
operator will propose a mining distance from ditches located on site that are not owned by
Western Mobile, Boulder/Lafarge.