GENERAL43218

• Permit No: M1988112
• IBM Index Class Name: General Documents
• Doc Date: 2/9/2000
• Doc Name: Clarification on Recommendations for Ground Water Monitoring in the San Luis Area
• From: US ENVIRONMENTAL PROTECTION AGENCY
• To: DMG
• Media Type: D
• Archive: No

o2/09100 R'ED 1J:59 FAE
•
water well or wellfield supplying a public water system through which conta^+;nants are
reasonably likely to move towazd and reach such well or wellfield. The extent of
wellhead protection azeas for public water supply wells in Colorado is defined in the
Colorado Wellhead Protection Program (CDPHE, 1994) and Colorado Sowce Water
Assessment and Protection Program (CDPHE, 2000) plans. The most common technique
used by the State to determine WHPAs is finding a 5-year time of travel using simple
analydeal equations or the semi-analytical WHPA 2.0 model.
What is the source water assessment process?
The completion of a source water assessment for a public water supply is required under
the Safe Drinking Water Act. For the State of Colorado's Source Water Assessment and
Protection Program the assessment phase must include fow elements: 1) delineation of
source water assessment azeas for each public water supply, 2) tut inventory of significant
potential sources of contaminants within the source water assessment area, 3 i a
determination of susceptibility of the public water supply intake or well to the inventoried
contaminants, and 4) active involvement of the public in the three steps above, including
public release of the results of the assessment. The techniques to be employed by
CDPHE in completing the source water assessments are defined in the Colorado Source
Water Assessment and Protection Program Plan (CDPHE, 2000).
When are the source water assessments going to be done?
Under the Safe Drinking Water Act the State of Colorado is required to complete source
water assessments for all public water supply systems within 42 months of El'A approval
of the State's program plan. CDPHE's Source Water Assessment and Protection
Program Plan was approved by EPA on February ??, 2000.
~ oos
Are there any other potential sources of contamination in the area to be concerned about?
J~u, ~r_n s, ,-aasar` i,e-~usl~n ~~~~,
EPA, CDPHE_ CDNR-DMG -- Fill in info ~- Q t-P Gl~'~t- P t$ `« e~ ~' ~
ft- L.q+JQ tztq.i_.l F•earru ~•-rzoea cF ertec1S
The results of the source water assessment for the town of San Luis water supply will
include all potential contaminant sources within the delineated Sowce water assessment
area. CDPHE has not yet completed an assessment for this public water system.
1~ ~
What are the potential contaminants from the mine site and are there health effects? ~ N'~,,~~~+
At this time the contaminants that are present in ground water within the former pit area 1'°'
are azsenic, iron, manganese, sulfate, and total dissolved solids. Arsenic is regulated
under the National Primary Drinking Water Regulations because of human health risks.
Health concerns for azsenic exposure for humans include damage to the skin, impacts on
the circulatory and nervous systems, and an increased risk of cancer. Sulfate, ~Hhich is
expected to be regulated under the proposed Sulfate Rule, can cause gastrointestinal
upset. Iron, manganese, and total dissolved solids aze considered undesirable in drinking
O
°o