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Lorenciro Canyon Mine ~ Surface µ'afer Technical ReDOrt
<br />• Material Damage with Respect to Alluvial Valley Floors, the Cumulative Hydrologic Impact
<br />Assessment, and Subsidence at Coal Mines (11/87).
<br />Exceedances in the metals standards were also determined. Since the standards for dissolved
<br />silver, free cyanide, dissolved copper, and dissolved mercury are very low, the detection limits
<br />for these samples often exceeded the standard. Sites BC-1 and CWC-I exceeded the CDMG
<br />material damage specific conductance standard of 700 umhos/cm. Exceedances for trivalent
<br />chromium were detected from samples obtained from the sediment samplers at the AC-1 and
<br />CWC-1 locations. Hexavalent chromium standards were exceeded in samples from AC-1, BC-1,
<br />CC-1, and LC-4, while total recoverable chromium was exceeded at BC-1 and LC-2. The
<br />trivalent chromium standard was exceeded at AC-1, BC-1, CWC-1, and LC-2. Iron standards for
<br />dissolved and total recoverable values were exceeded at sites AC-1, CWC-1, LC-4, and AC-1,
<br />BC-1, CC-1, CWC-1, JC-1, LC-2, LC-4, and PRGTY-1, respectively. Manganese exceeded
<br />standazds for dissolved and total recoverable at sites AC-l, BC-1, CC-1, and LC-2. Ammonia,
<br />nitrite, and nitrate as N (dissolved) standards were exceeded at all sites. Stations JC-1, LC-1, LC-
<br />4, PRGTY-1, and PRGTY-2 exceeded the standards for dissolved lead. Sulfate was exceeded at
<br />only one station, LC-2. TDS and TSS were exceeded at stations CWC-1 and LC-1, and AC-1 and
<br />JC-1, respectively. Zinc standazds were exceeded at only one site, LC-1. Each station exhibited
<br />characteristics which would restrict its use for aquatic life. A table summarizing the highest
<br />exceedances of the standards for each station is presented as Table SW-7.
<br />• SARs for the surface stations were below 5.0 at all stations. The highest values were obtained
<br />from the samples CWC-1 and JC-1. These samples also had conductivities of 700 µmhos and 550
<br />µmhos, with corresponding SARs of 4.77 and 4.24, respectively. The lowest values were
<br />obtained from the stations PRGTY-1 and PRGTY-2. These stations had conductivities of 352
<br />µmhos and 321 µmhos, with corresponding SARs of 0.63 and 0.46, respectively.
<br />Spring Stations
<br />Baseline reconnaissance identified 11 springs within the permit area. Flows ranged from 0.1
<br />g.p.m. to 12.25 g.p.m. Water quality sampling revealed slightly to moderately alkaline, slightly
<br />hard, calcium-sodium bicarbonate water, with total dissolved solids ranging from 300 mg/L to 710
<br />mg/L. Total alkalinity in the samples ranged from 223 mg/L to 409 mg/L, and hardness ranged
<br />(as CaCO~) from 214 mg/L to 388 mg/L. pH ranged from 6.70 to 9.15. A summary of the
<br />baseline monitoring results may be reviewed in Appendix SW-3. Determination of the water type
<br />was made using trilinear and Stiff type diagrams. These diagrams are included in Appendix SW-
<br />5. In addition, sodium absorption ratios (SARs) were compared to the Mined Land Reclamation
<br />Sandazds Division Procedures for the Assessment of Material Damage with Respect to Alluvial
<br />Valley Floors, the Cumulative Hydrologic Impact Assessment, and Subsidence at Coal Mines
<br />(11/87).
<br />•
<br />sw.475~December 4, 1996 17
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