GENERAL49542

• Permit No: M1994117
• IBM Index Class Name: General Documents
• Doc Date: 2/27/1996
• Doc Name: WATER BALANCE-GOLD HILL MILL-COLINA ORO MOLINO-COM-INC PN M-94-117
• From: DMG
• To: DUFFORD AND BROWN PC
• Media Type: D
• Archive: No

:;
•,
-.~
Letter to Richard Fanvo -2- February 20, 1996
DATES .. ".. :: ; :.
,.... :.#:: DAYS . INCHES ..: :..:;::

ACCUMUI~ATE~.. : INCHE$.:::

PER::DAY .GALLONS

PER DAY.:. : GALLONS.:PER

MINDTE ...::.::.::::::
12/10 to 12/18 8 28 3.50 1925 1.34
12/18 to 12/26 8 28 3.50 1925 1.34
12/26 to 12/31 5 27 5.40 2970 2.06
12/31 to 1/7 7 26 3.71 2040.5 1.42
1/7 to 1/15 8 24 3.00 1650 1.15
1/15 to 1/21 6 21 3.50 1925 1.34
':....::?SEAN VALIIES•.....: :... f:41 ..'. :: 2.42:9.. :::::.:' .:1:x.69.:. .. ...
The multiplier used in the above table to convert inches per day to
gallons per day is 550 gallons per inch. This multiplier was derived from
a graph provided by COM, Inc. in a letter from Richard Fox dated December
18, 1995. The graph is labelled "Hazel A Water Storage Capacity". The
550 gallons per inch multiplier utilized can be read from the graph in
that range of water heights reported in the water log maintained by COM,
Inc.
The data reported in the water log was accumulated over a 4 month period
that is representative of the low annual flow condition for ground water
inflows to the Hazel-A adit. During this low flow condition, the water
log data demonstrate that evaporative loss from the tailing pond has been
approximately equal to the rate of Hazel-A ground water inflows.
Evaporation from the Gold Hill Mill tailing pond has been estimated by
Richard Fox, for COM, inc., and these estimates are codified in a table
titled "Evaporation for Modified Tailings Pond" that is included in the
December 18, 1995 correspondence. It continues to be the Division's
position that site specific evaporation data need to be developed for the
Gold Hill Mill. However, using the COM, Inc, estimates, 3.9 inches net
evaporation occurs during the months of October, November, and December,
which are the months during which the water log data were recorded, and
a net evaporation of 0.84 inches occurs during the months of April, May,
and June, which is the period during which increased ground water inflows
to the Hazel-A may be anticipated. Clearly, evaporation by pumping up to
the tailing pond may not be relied upon to diminish any increased Hazel-A
inflows that may occur during April, May, and June. As such, it can be
expected that any increased ground water inflows that occur in the Hazel-A
adit during these months will result in a direct increase in accumulation
of water in the tailing pond.
The following is a parametric sensitivity analysis that quantifies the
accumulation of water in the tailing pond as it relates to a range of
ground water inflow rates for the Hazel-A adit. Values are converted to