GENERAL43258

• Permit No: C1980005
• IBM Index Class Name: General Documents
• Doc Date: 11/10/1992
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE FOR RN2
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

maintained in the channels of the two tributaries during the months of August
and September near their confluences with Fish Creek. The surface effects of
water discharged from the mine on the downstream AVF locations is restricted
to the months of June and July. Subsurface effects are expected to
predominate in August and September.
Water quality constituents of concern to the AVF identified on Fish Creek
include trace metals, sulfate, and TDS. An evaluation of concentration levels
present in the mine discharge indicate TDS to be the constituent most likely
to place a restriction on the quality of irrigation water. Rule 2.06.8(5)(b)
identifies material damage as increases in electroconductivity to levels above
a threshold value at which crop yields decrease. The relationship between
electroconductivity and TDS has been demonstrated level by Peabody Coal
Company, in the permit application.
The operator has submitted an analysis based on a mass-balance loading of TDS
in Fish Creek. Concentrations of TDS in mine effluent were the maximum values
from Spoils Spring Number 1 in the Cow Camp Creek drainage. Mean flow values
for June and July were used for Cow Camp Creek, Bond Creek, and an upstream
location on Fish Creek in the calculations. Results indicated significant
dilution would take place and maximum expected TDS concentrations of 607 mg/1
were expected in Fish Creek below the mine.
The maximum TDS level projected would correspond to a conductivity of less
than 1 mmho/cm. A conservative estimate of the relationship between
irrigation water salinity and root zone soil salinity, as referenced in
USDA Handbook 60, is 1 to 1.5, respectively. Thus, irrigation water applied
with a specific conductance of 1 mmho/cm would result in root zone soil water
with a specific conductance of 1.5 mmho/cm. No decrease in production of any
of the species identified in data submitted by the operator would be expected
unless the conductivity of the irrigation water were to exceed 1 mnho/cm. No
significant decreases in productivity would occur unless root zone soil water
salinity were to exceed 1.5 mmho/cm.
Given the limited effect of Seneca II Mine discharge on Fish Creek surface
water quality, it is deduced that alluvial ground water quality should not be
significantly impaired. Recharge of the Fish Creek alluvium from the Cow Camp
and Bond Creek tributaries would be expected to be minimal compared to
upstream contributions. Sub-irrigation would be expected to be less affected
by mine discharge than irrigation using surface waters. A conservative
estimate of the expected effect of mining indicates that no material damage
would resul t.
The following findings are in order for the alluvial valley floor known
as Fish Creek:
1. The Division finds that activities proposed by the applicant will
not interrupt, discontinue, or preclude farming on the alluvial
valley floors that are irrigated or naturally sub-irrigated.
(4.24.3(1)).
2. The proposed activities will not materially damage the quantity or
quality of water in the surface or ground water system described
above. (4.24.3(3) and 2.06.8(5)(a)gii)).
3. The proposed activities will comply with the requirements of the Act
and the Regulations with respect to alluvial valley floors.
(2.06.8(5)9a)(iii)).
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