REP35015

• Permit No: C1980001
• IBM Index Class Name: Report
• Doc Date: 2/16/1988
• Doc Name: PITTSBURG & MIDWAYS EDNA MINE AHR C-80-001
• From: MLRD
• To: PETER V OCONNOR
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

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STATE OF COLORADO (J ~
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Roy Romer, Govei
DEPARTMENT OF NATURAL RESOURCES
MINED LAND RECLAMATION DIVISION
FRED R. BANTA, Director
DATE: February lb, 1988
T0: Peter V, O'Connor
FROM: Cathy Begej ('~:~`i1,..1
RE: PITTSBURG AND MIDWAY'S EDNA MINE ANR, C-80-001
Water Quality Evaluation
The Edna Mine is exhibiting a standard case of spoil aquifer discharge and
impact to adjacent surface water and alluvium, Trout Creek surface water
changes from a calcium bicarbonate water with a TDS of 100 mg/1 upstream of
the disturbed area to a calcium/magnesium sulfate water with a TDS of 550 mg/1
at site TR-B, midway through the permit area. By the northern permit
boundary, the TDS drops to 300 mg/1,
This change in water type is presumably caused by spoils water, Spoils well
WR-1 is a calcium sulfate water averaging 3323 mg/1 TDS. The box cut seep was
monitored by Anne Baldrige, Colorado Mined Land Reclamation Division, in
August of 1985, and is characterized as a magnesium sulfate water with 4600
mg/1 TDS. The spoils waters appear to be free of toxic metals, but do exceed
irrigation standards for EC, aquatic life standards for nitrite, stock
watering standards for manganese and domestic standards for iron and sulfate
levels.
Many of the alluvial wells along Trout Creek have been influenced by mining
activities. One well, TR-15, is an upstream well with calcium bicarbonate
water and a TDS 140 mg/1, The operator indicates that TR-1, the furthest
upstream well is adjacent to a discharging underground mine. The
calcium~nagnesium sulfate water ranges in salinity from 1410 mg/1 to 2500
mg/1. TR-2 is below the East Ridge and is a calcium-magnesium sulfate water
with a TDS of 3300 mg/1. The operator suggests that water quality at this
site is impacted by irrigation return flows; I would add that this water has
flowed through the spoils.
The lower two wells, south and north of the Moffat area are calcium sulfate
type water with TDS averaging 400 mg/1, The operator notes that alluvial
water quality may be impacted by Wadge Coal seam outcrops in the north part of
the permit area, which would account for the predominance of sulfate and
increased TDS over what's been observed at TR-1.5. Alternatively, these wells
could have been affected by lower quality surface water recharging the
alluvium, TR-3's salinity has increased moderately in the last eight years of
monitoring. TR-4 has not exhibited specific trends with regard to salinity.
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. [phone]