Document 6REa1yZQbDep55nGJQoG4L3V6
United States Department of the interior
.
BUREAU OF MINES
02081250
603 Miller Court Lakewood, Colorado 30215
________
ROCKY MOUNTAIN DISTRICT Metal & Nonmetal Mine Health & Safety
Denver Subdistrict
">.:AR [ cc" ' :
February 27, 1973
File HLS
H. A. Brown Vice President, Operations Construction Products Division W. R. Grace & Co. 62 Whlttemore Ave. Cambridge, Massacusetts 02140
Subject: .
Airborne Dust Concentrations Zonolite Mine-Mill. W. R. Grace and Company
Libby, Lincoln County, Montana January 29-February 8, 1973 By Jack Petty
Dear Mr. Brown:
Attached is a table listing the fiber concentrations of airborne dust concentrations taken during Che recent inspection of your Libby, Montana mine and mill. These concentrations are so tar above the recommended threshold limit values, as high as 20 times, as to require your immediate attention. These samples represent a marked Increase over previous samples indicating a failure of current control measures to reduce dust concentrations at this operation.
Sincerely yours.
Enclosure cc: R. L. Oliverio, Manager
D. K. Walker Subdistriet Manager
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