2008-08-20_REPORT - M2005071

• Permit No: M2005071
• IBM Index Class Name: REPORT
• Doc Date: 8/20/2008
• Doc Name: Ground vibratons at Benson Brothers Red Shale Quarry
• From: REVEY Associates, Inc.
• To: DRMS
• Email Name: THM
• Media Type: D
• Archive: No

PreSeisTek 8174 S. Holly St., Suite 402, Centennial, CO 80112-4004
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Email: [e-mail]
August 28, 2006
RECEI'VED
AUG'2 0 2008
Attention: Ed Benson GRAND JUNCTION i-itd) OFFICE
21240 Austin Road DIVISION OF
Austin, CO 81410 RECLAMATION MINING & SAFETY
RE: Review and Analysis of measured ground motions caused by excavator, doers and
operating crushers.
Background and Introduction
PreSeisTek, Inc. (PreSeisTek) was retained by Benson Brothers and Revey Associates to
collect vibration data at the Benson Brothers Red Shale Quarry in Austin Colorado The
purpose of the data collection is to determine the level of vibration occurring in the
Quarry area specifically at the rock bluffs above the Croissant property and other area
property.
On Tuesday July 15th, 2008 at approximately 9:00 a.m. PreSeisTek began setting up one
(1) White Seismology seismograph at Global Positioning Station (GPS) N- 38'55.720,
W- 107'58.179 on the Quarry site. The unit Serial number 932 had been calibrated within
one (1) year. The unit was set up in bargraph mode to pulse every 6 seconds for vibration
between the hours of 8:00 a.m. and 5:00-p.m. for 30 days. At the same time PreSeisTek,
Inc. conducted a study at the site colleting vibration data at 5 different locations while the
heavy equipment was running. The quarry was shut down while parts (high pressure
relief valve and accumulator) were ordered for the cone crusher between July 16th and
July 23rd. During this time the seismic equipment did not collect data.
Location of Seismograph
It should be understood that the placement of the unit was decided based on the collection
of data that was collected in the study where 5 different locations were monitored for
vibration. This site was selected at a distance of at least '/2 mile from the rock bluffs so
that data could actually be collected. Had we moved the unit closer to the bluffs we