1999-02-24_REVISION - M1999002

• Permit No: M1999002
• IBM Index Class Name: Revision
• Doc Date: 2/24/1999
• Doc Name: DMG GROUND WATER POLICY
• Type & Sequence: TR3
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOFY
Deparlntem of Natural Resources ---
171 4 Sherman 81.. Room ? I S 1^,
Denver, Colorado 80?03 /~ C ~a„ //t ~ ~
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D I v 15 I O N O F
MIN &RA L S

GEOLOGY
To: Minerals Program Teams
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From: Bruce Humphries
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---~ R E C L A M A T I O N
MI NING•SAFETY
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/ Bill Owens
Date: 02/24/99 / Governor
Greg E. Walther
Re: Ground Water Protection Policy fKe[ulivn D~reclur
hLCharl 8. Long
Dwision Director
Use of the policy issues addressed in this memo and attachment assumes a thorough familiarity with MLRB
Rule 3.1.7 and with Regulation No. 41, the Basic Standards for Ground Water of the Water Quality Control
Commission (WQCC), including the Statements of Basis and Purpose for these regulations. Enclosed with
this memo are three pages from a recent adequacy review that highlight some of the precepts for
implementation of the ground water regulations. Note, in particular:
/ For a statistical analysis of ambient ground water data using DMG software (DumpStat) a minimum of
eight data points are required. More data points maybe required depending on the variance of the data.
Operators should design their ambient characterization sample collection plan such that the timing of
sample collection will coincide with anticipated seasonal fluctuations of the water table elevation. In
shallow ground water/rapid recharge regimes, operators should consider collecting samples following
storm events as well as collecting samples during extended dry periods. Climatic conditions leading up
to the sample collection event should be documented by the sampler. These measures will serve to
better assure that that the full spectrum of ground water conditions are analyzed.
/ Numeric protection levels are established in unclassified areas in accordance with the Interim Narrative
Standard of the WQCC. In areas where the WQCC has established standards, those standards are
applied. If the DMG establishes numeric protection levels at an unclassified location, and the location is
subsequently classified, the WQCC standards will supersede the numeric protection levels.
/ Ambient ground water quality may be established through the use of down gradient wells prior to the
introduction of a contaminant source, by using upgradient wells following the introduction of a source, or,
for site with extant contaminant sources, using best professional judgement as to what constitutes
adequate information to determine or estimate the ground water quality that existed on January 31,1994.
/ If the leading edge of an expanding zone of ground water contamination can be delineated at existing
sites, the Interim Narrative Standard does not allow for expansion of the zone unless the contaminant
levels are below applicable standards, except that the DMG is provided with some flexibility to establish
the location of points of compliance as described in Rule 3.1.7(6).
/ In accordance with Rule 3.1.7(5), permit conditions relative to ground water such as points of compliance
and numeric protection levels may be established or modified via the technical revision process.
The ground water compliance protocol included in the attachment was developed by Dr. Jim Stevens; other
elements of the policy were developed with input from Dr. Stevens, Dr. Harry Posey and Allen Sorenson.
Enclosure(s) c:\vnndows~persona~ground water precepts.doc