GENERAL42418

• Permit No: M1980244
• IBM Index Class Name: General Documents
• Doc Date: 6/15/1995
• Doc Name: FAX COVER PROVISION OF INFORMATION UPDATING THE ESITMATION OF LEAKAGE RATES
• From: CRIPPLE CREEK & VICTOR GOLD MINING CO
• To: DMG
• Media Type: D
• Archive: No

Golder Assxlafes Ina //''t~ ~~
200 Union Boulevard. Suite 500 AW^^Aid~t'^Y~
Lakewood. CO USA 80228 ~ ~ 1'~~`S
Telephone[phone]~0540
Fax [phone]
May 24, 1995 Project No.:943-2847
Cripple Creek & Victor Gold Mining Company
2755 State Highway 67
Victor, CO 80860
Attention: Mr. John Hardaway
RE: REVIEW OF THE LOW VOLUME SOLUTION COLLECTION SYSTEM ACTION
LEAKAGE LIMIT RATES
Dear John:
Golder Associates Inc. (Golder) has evaluated the Low Volume Solution Collection System (LVSCS)
Action Leakage Rates (ALR's) for the Phase i Heap Leach Pad.
BACKGROUND
A liner leakage evaluation was conducted for the Phase 1 Pregnant Pond to evaluate the theoretical flow
rates expected during normal operating conditions. Leakage rates were calculated using methods proposed
by Gtroud & Bonaparte (1989) and Van Zyl (1990), for the evaluation of leakage through a single hole in a
liner. The basic premise for all liner leakage results presented herein are that, even if careful construction
and quality assurance are maintained during liner installation, one hole per acre could still be present in the
geosynthetic liner system at a well conswcced mining installation (Van Zyl, 1990).
For modeling purposes, the geomembrane was assumed to be located between two infinitely permeable
media. Giroud & Bonaparte (1989) used Bernoulli's equation for free flow through an orifice to calculate
the flow through the primary liner as follows: Q = Cn A 2gh
Equation [ I ]
where:
Q = Flow rate through hole (m'/s)
Cb = Numeric Coefficient (0.6)
A = Area of hole (m'-)
g = Acceleration due to gravity (m/s'')
h = Depth of fluid (m)
Based on the above equation, leakage through the liner is controlled by the following parameters:
• Characteristics of the underlying material;
• Depth of Fluid or hydraulic head; and,
• Number and area of defects.
The underlying material was assumed to be infinitely permeable. A Low Volume Solution Collection
System (LVSCS) is present so that any solution collected above the composite liner system would be
pumped out and the head on the composite liner system would be minimized.
In developing the EPA background document on liner leakage for solid waste facilities. Bonaparte et. al.
(1987) recommended that a defect with a diameter of 2 mm be appropriate for estimating ALR's as a result
of flow into the leakage collection layer under typical operating conditions.
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