2015-08-12_INSPECTION - M1980244

• Permit No: M1980244
• IBM Index Class Name: Inspection
• Doc Date: 8/12/2015
• Doc Name: Inspection Report
• From: DRMS
• To: CC&V
• Inspection Date: 8/12/2015
• Email Name: AME
• Media Type: D
• Archive: No

PERMIT #: M-1980-244
INSPECTOR’S INITIALS: AME
INSPECTION DATE: August 12, 2015

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OBSERVATIONS

This was a normal monitoring inspection of the Cresson Project (Permit No. 1980-244) conducted by Amy
Eschberger of the Division of Reclamation, Mining and Safety (Division). Jeff Campbell, the Senior
Environmental Coordinator was present during the inspection. This is a 112d-3 heap leach gold mining
operation with an approved permit area of 5,989.70 acres. The approved post-mining land use is rangeland and
wildlife habitat. This was a partial inspection conducted as part of the Division’s latest objective to inspect this
site monthly to monitor major construction projects such as the Squaw Gulch Valley Leach Facility (SGVLF)
and to periodically inspect Environmental Protection Facilities and other potentially contaminated areas.

During this inspection, the following facilities were inspected:

 Buckley Annex/Bulk Emulsion Facility
 Explosives Storage Area

In addition, the inspection included the following activities:

 Observed manual water level readings of Phase II & III pond piezometer and high volume solution
collection system (HVSCS) pump #5
 Recorded water level readings for Arequa Gulch Valley Leach Facility (AGVLF)
 Observed construction activities in SGVLF
 Observed scheduled blasting event in Main Cresson Mine
 Conducted post-inspection meeting with Chris Hanks and Jeff Campbell

Buckley Annex/Bulk Emulsion Facility:
This facility is located at the eastern edge of the Ironclad complex, adjacent to the southern portion of the East
Cresson Mine Wildhorse Extension. The facility includes a processing warehouse, a truck and equipment
storage warehouse, and a portable office trailer. The inspector was escorted through the facility by John
Garamendi, Aaron Cash, and Jeff Campbell. The operator’s supplier, Buckley Powder Company does not allow
photographs to be taken inside or around the facility. According to Mr. Garamendi and Mr. Cash, the facility
has had some major upgrades in the past few years to accommodate their conversion to using a different
blasting agent (described below).

From 1999 to 2012, the mining operation used a gassed and augered 50/50 heavy ammonium nitrate fuel oil
(ANFO) bulk blasting agent as the main explosive charge for its ore and overburden blasting operations. Drill
holes containing minimal amounts of water were dewatered and loaded with augered chemically gassed 50/50
heavy ANFO blend while drill holes containing significant amounts of water were pumped with a 70/30 re-
pumpable emulsion/ANFO blasting agent. Since 2012, the operation has phased out the use of ANFO in their
blasting applications and begun using straight (100%) emulsion, which they manufacture on site.

Using straight emulsion has many benefits over ANFO, including, minimum generation of noxious fumes (NO2
and NO) and less smoke, better water resistance (for wet holes), higher energy, ability to obtain high velocity of
detonation (VOD), safer handling and storage (due to relative insensitivity to detonation by friction, impact, or
fire), and ability to use variable densities when loading the holes which allows for a cleaner blast pattern. The
emulsion is manufactured in this facility by mixing two immiscible oxidizer and fuel phases and adding an
emulsifying agent to help stabilize against liquid separation. The internal phase is composed of a solution of
oxidizer salts (e.g., Ammonium Nitrate) dispersed as microscopically fine droplets inside an
external/continuous fuel phase (e.g., mineral oil, diesel fuel). The fuel phase is pumped from three tanks, a