2016-10-25_REVISION - C2009087 ‎(3)‎

• Permit No: C2009087
• IBM Index Class Name: Revision
• Doc Date: 10/25/2016
• Doc Name: Adequacy Review Response
• From: Peabody Sage Creek Mining, LLC
• To: DRMS
• Type & Sequence: TR9
• Email Name: JLE
• Email Name: DIH
• Media Type: D
• Archive: No

RULE 2 -PERMITS
Alternative Water Supply Information — Additional details relative to the potential for
contamination, diminution, or interruption of water supplies is presented in Section 2.05.6(3),
Protection of Hydrologic Balance.
Groundwater Monitoring — A groundwater monitoring program will be implemented to monitor the
groundwater to determine: 1) the effects of mining activities on the quantity and quality of water in the
groundwater systems in the permit area and adjacent area; and 2) compliance with applicable
groundwater standards at established points of compliance. The proposed monitoring program covers
groundwater in the overburden, Wadge Coal, alluvium, and the Seneca reclaimed spoils aquifer. All
monitoring and sampling will be conducted in accordance with CDRMS guidance regarding sampling
methods, measurement of parameters in the field and laboratory, and required analytical parameters
including Section 4.05.13 and applicable subsections. Evaluations of trends in parameter
concentrations over time and comparison of those concentrations to groundwater protection standards
will be made. Existing data establishes the baseline for the aquifers, which include transient impacts
from previous activities in the watershed. A discussion of the potential hydrologic consequences of the
proposed PSCM relative to baseline conditions is presented in Section 2.05.6(3).
Table 2.04.7-T9 lists the wells to be included in the monitoring program during active mining status,
mincluding monitoring frequencies and the parameter list used. Table 2.04.7-T9.1 list the wells to be
included in the monitoring program monitoring frequencies during inactive/idle mining status. Tables
2.04.7-T10 and T10.1 lists the water quality parameters to be measured in the field and those to be
measured or analyzed in the laboratory. Details regarding the construction of the wells and the results
of monitoring to date are provided in Exhibit 2.04.7-E1, Hydrologic Information. Groundwater
monitoring data will be submitted to CDRMS in annual reports by March 31St of each year.
The proposed point of compliance (POC) is well SGAL70, completed in the Grassy Creek alluvium
approximately 1000 feet downstream of the permit boundary. This well has been monitored for water
levels and water quality since 1988 and provides a long period of historical record against which to
compare newly -acquired data. This well was approved by the CDRMS as a POC well for the Seneca
II mine in March 2009 under TR -47. In TR -47, bedrock POC wells were not deemed necessary due to
low hydraulic conductivities and well yields, and because attenuation and dilution should assist in
limiting water quality impacts on bedrock units from mining activities to close downgradient
proximities. Since the same bedrock units that were determined in TR -47 by CDRMS to not require
POC's will be affected by mining activites at the PSCM, PSCM does not propose to establish POC's
for these units.
There are four monitoring wells used for determing hydrologic impacts from the Seneca II Mine that
are proposed for including in the PSCM monitoring program. These wells are SOV42 (Wadge
Overburden), SSP61 (Little Grassy Creek Spoils), SSP62 (NPDES4 Basin Spoils), and SCAL69
(NPDES4 Basin Alluvium). These wells are included in the following Tables 2.04.7-T9 and T9.1,
and details regarding the construction of the wells are provided in Exhibit 2.04.7-E1.
TR09-16 2.04-103 10/25/16