GENERAL46440

• Permit No: C1981012
• IBM Index Class Name: General Documents
• Doc Date: 12/31/1992
• Doc Name: Midterm Review Findings Document
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

3. Hydrology
A) PRS-1 is the monitoring point for surface water upstream of the New
Elk Mine. According to the 1991 Annual Hydrology Report, TRS-2 is
the monitoring point for surface water downstream of the New Elk
Mine. However, PRS-2 is also downstream of the point where the
North Fork of the Purgatoire River joins the Purgatoire River.
Comparison between PRS-1 and PRS-2 cannot be made because of the
dilution effect of the North Fork waters on PRS-2.
On the map provided with the 1991 AHR entitled "Monitoring
Locations", there is a PRS-4, a station downstream of the New Elk
Mine but upstream of the point where the North Fork enters the
Purgatoire River. What is the status of this monitoring station?
Can it be reactiviated in order to properly evaluate the effect of
the New Elk Mine on the Purgatoire River?
B) Since 1986, TDS, sodium and sulfate concentrations in PAW-3
generally have been higher than in PAW-4. Both wells are in the
backfilled channel of the river but PAW-3 is upstream of PAW-4 by
100 yards. Is PAW-3 intended to be an upgradient well and PAW-4
intended to be a downgradient well? If so, please explain why the
upgradient well has higher concentrations of TDS, sodium and
sulfate than the downgradient well.
If PAW-3 and PAW-4 are not upgradient and downgradient wells, then
what is the intention of having these 2 wells? Should there be
upgradient antl downgradient wells which are located outside of the
backfilled area, rather than in the backfilled area'
C) As stated in the 1991 AHR, it appears that the RDA is leaching
contaminants into the Purgatoire River alluvial aquifer, as
evidenced by water quality data from PAW-1 and PAW-2. Please
explain the source of the contamination and how it impacts the PHC
for the New Elk Permit.
X D) Add ditch data from D 32 and D 33 to Table 20, page 2.05-11.
E) There is a discrepancy in design ditch type data between Table 20,
page 2.05-11 and Map 13 for ditch numbers 3, 4 15 and 30.
~~ F> In Table 21, page 2.05-14, add culvert sizing data for culvert
Numbers 14, 22, 26 and 38 through 44.
G) In Table 21, page 2.05-14 and Map 13, there is a discrepancy in the
minimum culvert diameter data for culverts 12, 35 and 36. Also
culverts 23 and 24 are missing diameter data.
H) Update the Annual Hydrology Repot in Exhibit 12.
I) Update the Pu~yatoire Riker diversion ~~irvey in Exhibit Z1.
J~ Update the NPDES permit in Exh~u ~ 27