2018-11-15_HYDROLOGY - M1980244 ‎(6)‎

• Permit No: M1980244
• IBM Index Class Name: HYDROLOGY
• Doc Date: 11/15/2018
• Doc Name Note: Demonstration of Compliance w/WQCC's Regulation #41 - Basic Standards for GW
• Doc Name: Part 1 of 5
• From: CC&V
• To: DRMS
• Email Name: AME
• Email Name: TC1
• Email Name: MAC
• Email Name: ERR
• Email Name: JPL
• Media Type: D
• Archive: No

data generated after January 31, 1994 which exceeds Table Value Standards and can also
demonstrate that no new or increased sources of groundwater contamination in the area in
question have been initiated since January 31, 1994, and therefore ambient conditions exceeded
Table Value Standards prior to January 31, 1994."
The interpretation in DRMS's December 2016 letter is inconsistent with the language of Regulation 41.
Section 41.5(C)(6)(b)(iii)requires the DRMS to exercise its best professional judgment to determine what
constitutes adequate information to determine or estimate existing ambient quality. This requires
consideration of all data. The regulation then creates a presumption that data after January 31, 1994, are
representative of existing quality as of January 31, 1994, if the available information indicates that there
have been no new or increased sources of groundwater contamination initiated in the area in question
after that date. The regulation does not create a "narrow circumstance" for consideration of data after
January 31, 1994; instead, it directs DRMS to weigh all the data but to apply a presumption that the data
are representative of conditions before January 31, 1994, if the required conditions are met.
Finally,the December 2016 DRMS letter asserted:
"[FJor any NPL for a monitored analyte exceeding the applicable Table Value Standards to be
valid, it will be the operator's burden to provide sufficient data and rationale to demonstrate to
the satisfaction of DBMS and WQCC that at least one of the two conditions previously listed
which would allow DRMS to apply a less restrictive standard have been met. "
NPLs previously determined by the DRMS were based on data and information that CC&V submitted to
DRMS at the time of approval and are presumptively valid. CC&V does not agree that it is the burden of
the operator to establish the validity of previously-established NPLs, many of which were determined 20
or more years ago. Instead, as stated in the letter from DRMS to CC&V dated October 7 1996,
establishing numeric standards for the Cresson Project, the standards apply to all monitoring wells unless
CC&V makes a written request for a change of the standards. Therefore, CC&V bears the burden of
making the demonstration only for newly-proposed NPLs.
In December 2016, CC&V proposed NPLs for seven compliance monitoring points. (CC&V, 2016,
Table 2-1). The proposed NPLs are given in Table 1, and the locations of the drainages are shown in
Figure 1.
Table 1: Proposed NPLs (CC&V, 2016) and domestic well standards (t is total, d is dissolved, WCMW 3
and 6 are in the Wilson Creek drainage).
Drainage Sulfate(t) pH Manganese(d) Zinc (d) WAD CN
(m L) (mg/L) (mg/L) (m /L)
Arequa Gulch 1070 6 -9 8.1 2 0.2
Grassy Valley 250 6 -9 1 2 0.2
Vindicator Valley 800 6.5—8.5 4 2 0.2
WCMW 3 250 6 -9 0.5 2 0.2
WCMW 6 250 6 -9 0.5 2 0.2
Squaw Gulch 1070 6.5—8.5 8.1 2 0.2
Poverty Gulch 1070 6—8.5 8.1 2 0.2
Domestic Wells 250 6.5—8.5 0.05 5 0.2
The remainder of this document provides an analysis and presentation of the data and recommendations
for the CC&V proposed NPLs.
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