PUBLIC HEALTH ASSESSMENT
SUMMITVILLE MINE
DEL NORTE, RIO GRANDE COUNTY, COLORADO
Figure 1 - General Summitville Area Map
Figure 2 - Downstream of the Summitville Mine Site
Figure 3 - Site-specific Map of Summitville Mine
Figure 1. Surface Water Sampling Locations Near Summitville Mine NPL Site
Figure 2. Summitville Surface Water Sampling Locations on the Lower Alamosa River
Figure 3. Summitville Mine NPL Site
Table 1 - Riverwater Downstream of the Mine Site
Table 2 - Off-Site Domestic Water
Table 3 - Completed Exposure Pathway at the Summitville Site
Explanation of Environmental Contaminant Data Tables
ATSDR selected the contaminants in the data tables for further evaluation based on those contaminants (predominantly metals) being released to surface water at the Summitville Mine site and any metals that were above federal drinking water standards in private wells. ATSDR uses comparison values--contaminant concentrations in specific media considered protective of public health--to select contaminants for further evaluation. ATSDR and other agencies have developed the comparison values to provide guidelines for estimating contaminant concentrations in media that are not likely to cause adverse health effects, given a standard daily ingestion rate and standard body weight.
The comparison values in Tables 1 and 2 are primarily the drinking water standards, such as the maximum contaminant levels (MCLs), established by EPA. MCLs are limits on chemical concentrations in drinking water that EPA considers protective of public health (considering the availability and cost-effectiveness of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day (for an adult). Maximum contaminant level goals (MCLGs) are EPA drinking water health goals set at levels at which no known or anticipated adverse health effects would be experienced by exposed persons. MCLs are EPA regulations that can be enforced; MCLGs are goals that are not enforceable. EPA also has lifetime health advisories (LTHAs) for drinking water. If ATSDR or EPA comparison values are not available, ATSDR may refer to other agencies' standards as applicable.
| = Maximum Contaminant Level | |
| = Maximum Contaminant Level Goal | |
| = parts per billion | |
| = parts per million | |
standard |
= the number of times a concentration exceeded the standard value compared to the number of times it was analyzed. |
| RIVER WATER DOWNSTREAM OF MINE SITE April 1993- November 1995 | |||||||
| Stations Progressively Downstream* [Figures 1 and 2] Concentrations (ppm) | |||||||
| Parameter | Represents: | WF-5.5 | WF-0.0 | AR-45.4 | AR-34.5 | AR-31 | Federal drinking water standard (ppm) |
| Field pH | range | 3.3-4.7 | 3.8-7.5 | 4.4-5.4 | 4.9-7.0 | 5.1-7.3 | |
| Avg. | 3.7 | 4.9 | 4.9 | 5.9 | 6.3 | ---- | |
| Total Cyanide | Max. | 1.52 | 0.314 | 0.090 | 0.031 | 0.029 | |
| Avg. | 0.168 | 0.146 | 0.017 | 0.023 | 0.009 | 0.200 MCL** | |
| Cyanide-WAD | Max. | 0.590 | 0.105 | 0.042 | 0.021 | 0.014 | |
| Avg. | 0.127 | 0.053 | 0.017 | 0.013 | 0.009 | 0.200 MCL** | |
| Aluminum | Max. | 71.05 | 18.46 | 7.98 | 20.20 | 3.24 | |
| Avg. | 33.96 | 8.65 | 4.38 | 5.55 | 0.45 | None | |
| Cadmium | Max. | 0.051 | 0.035 | 0.005 | 0.006 | 0.003 | |
| Avg. | 0.011 | 0.011 | 0.002 | 0.002 | 0.001 | 0.005 MCL | |
| Copper | Max. | 40.9 | 13.6 | 3.9 | 1.5 | 0.5 | |
| Avg. | 8.0 | 4.2 | 1.1 | 0.7 | 0.3 | 1.3 MCLG | |
| Iron | Max. | 95.7 | 34.7 | 14.2 | 80.7 | 15.4 | |
| Avg. | 46.2 | 14.9 | 8.6 | 11.9 | 1.7 | None | |
| Lead | Max. | 0.054 | 0.330 | .007 | 0.052 | 0.008 | |
| Avg. | 0.015 | 0.014 | .003 | 0.016 | 0.002 | 0.015 EPA action level | |
| Manganese | Max. | 24.59 | 4.95 | 1.47 | 2.75 | 0.94 | |
| Avg. | 8.27 | 3.56 | 0.77 | 1.16 | 0.47 | None | |
| Zinc | Max. | 6.7 | 2.6 | 0.8 | 1.3 | 0.3 | |
| Avg. | 4.0 | 1.1 | 0.4 | 0.3 | 0.2 | 10 MCL | |
| * Signs are posted warning people not to drink contaminated river water. These river segments are not classified for
drinking water use but for agricultural and recreational uses. ** The cyanide drinking water comparison value is for free cyanide (HCN or CN). Only some of the total or WAD cyanide concentrations would be free cyanide. Most of the cyanide in these concentrations would be in the form of metal cyanide complexes. The metals concentrations are total recoverable concentrations. WAD = Weak Acid Dissociable See Figures 1 and 2 for locations | |||||||
|
OFF-SITE DOMESTIC WATER | ||||
| PARAMETER | MAXIMUM CONCENTRATION (ppb) or pH range |
SEASON (1993) |
FEDERAL DRINKING WATER STANDARDS (ppb)/Source |
FREQ > STANDARD |
| pH range |
6.6 - 8.5 6.6 - 8.8 NA |
Spring* Fall 1 Fall 2 |
--- | --- |
| Aluminum | 100 300 NA |
Spring Fall 1 Fall 2 |
none | --- |
| Cadmium | 20 10*** <4 |
Spring Fall 1 Fall 2 |
5 MCL | ** 3/30*** 0/4 |
| Copper | 550 200 440 |
Spring Fall 1 Fall 2 |
none | |
| Iron | 1,400 410 160 |
Spring Fall 1 Fall 2 |
none | |
| Lead | 240 70 NA |
Spring Fall 1 Fall 2 |
15 EPA action level | **** ***** --- |
| Manganese | 1,750 530 5 |
Spring Fall 1 Fall 2 |
none | |
| Zinc | 360 440 17 |
Spring Fall 1 Fall 2 |
10,000MCL | 0/75 0/30 0/4 |
| Sulfate | 83,000 167,000 NA |
Spring Fall 1 Fall 2 |
500,000 PMCL | 0/75 0/30 --- |
| NA = Not Analyzed *Spring - March through June CSU results Fall 1 - October through November CSU results Fall 2 - Resampling in November by State of Colorado ** Detection limit of 10 ppb is above comparison value of 5 ppb, 1 sample out of 75 samples (1/75) exceeded 10 ppb. | ||||
| Pathway Name | Point of Exposure | Route of Exposure | Exposed Population | Time of Exposure | Contaminant | Estimated Exposed Population |
| Air | Heap Leach Pad | Inhalation Skin Contact |
Heavy Equipment Operators at Summitville Mine |
Past | Cyanide | <10 |
Appendix Three- Public Comments
Responses to Comments Received During the Public Comment Period for the Summitville Mine site.
The public comment period for the public health assessment (PHA) for the Summitville Mine site was April 18 through May 23, 1997. The PHA is available at three repositories: the Del Norte Public Library in Del Norte, Conejos County Agricultural and Soil Conservation Service in La Jara, and the Environmental Protection Agency (EPA) Superfund Records Center in Denver. The Summitville technical assistance grant (TAG) coordinator received copies of the PHA for distribution to a local citizens group. Comments from this group and their technical advisor and our responses to those comments follow. Repetitive comments were omitted, and some comments have been condensed. However, anyone can request the original letters from the Agency for Toxic Substances and Disease Registry (ATSDR) through the Freedom of Information Act process. ATSDR also received comments from the Colorado Department of Public Health and Environment and has made changes to the public health assessment based on these comments. Those comments are not included here, but they are available, along with any other comments, from ATSDR through the Freedom of Information Act process.
COMMENT: Why haven't the Federal Secondary Drinking Water Standards been used in evaluating drinking water quality? It is very important that water tastes good and that there are no foul odors or colors.
RESPONSE: Our focus was to determine whether the contaminants in groundwater could cause adverse human health effects. We used the primary drinking water standards (primarily the maximum contaminant levels [MCLs]) because they are enforceable, health-based standards. Secondary maximum contaminant levels (SMCLs) represent reasonable goals for drinking water quality but are not enforceable. They are guidelines for odor, color, taste, and other aesthetic qualities.
Some of the metals in private wells influenced by Alamosa River water (For example: aluminum, iron, and manganese) exceed SMCLs established by the EPA.(1) The SMCL for aluminum is a range of 0.05 to 0.2 parts per million (ppm). The SMCL for manganese is 0.05 ppm. Excess manganese produces a brownish color in laundered goods and affects the taste of beverages. Concentrations exceeding the SMCL may cause dark brown or black stains on plumbing fixtures and may coat distribution pipes. Iron will also produce a brownish color in laundered clothing, and it stains plumbing fixtures with a characteristic rust color. Iron can be tasted at 1 ppm and has a bitter, astringent taste.
Copper concentrations in 1993 private well data are below 1 ppm, the concentration states usually establish as an SMCL. Copper at concentrations exceeding 2 ppm usually causes significant staining and unpleasant tastes. Many people can taste copper at 1 ppm. The optimum range for pH is around neutral or 7, 6.5 to 8.5.
Residents whose wells are or could be influenced by Alamosa River water downstream of the Summitville Mine site should contact The Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Commission, if they are concerned about or notice changes in water quality.
COMMENT: According to ATSDR, three main sources- the heap leach pad, french drain, and Reynolds Adit "and other associated acid drainages"- have released contamination from the site. Do those other associated acid drainages include the Cropsy foot print? How about seeps and springs from plugging? Uncontrolled pollution that flows from the Cropsy footprint negates pollution control efforts in other parts of the mine site.
RESPONSE: Yes, the other acid drainages include all of the ones mentioned. Plugging the adits has substantially reduced the volume of water being released from the site and, therefore, the metal loading to streams. Although the uncontrolled pollution from the Cropsy footprint contributes to metal loading of streams, it does not negate the reduction in metal loading that results from plugging.
COMMENT: There is possibly premature judgement on groundwater quality since there will undoubtedly be a time delay before contaminated water that has been released into the Alamosa River has had a chance to reach the groundwater unless there is direct contamination from surface water sources.
RESPONSE: ATSDR has suggested continued monitoring of surface water for use as an indicator of the potential for groundwater contamination. We have added in this version of the PHA a recommendation for a private well sampling program to confirm 1995 results and assure residents that their drinking water is safe. We have recommended sampling private wells during surface water sampling.
COMMENT: In the document it has been recommended that surface water continue to be monitored in order to assess the impacts on the groundwater without saying anywhere in the document that groundwater should also continue to be monitored. It would be rather difficult to assess the impacts on groundwater without continuing to monitor the groundwater as well.
RESPONSE: We have recommended a phased approached that suggests that surface water be used as an indicator. However, the best of all worlds would be to have private wells tested during surface water sampling. Since conditions may change (irrigation ditches may be lined, lessening the volume of water entering wells; the soil's capacity to retain metals may change, etc.), we have recommended further sampling to confirm that private wells are not being influenced.
COMMENT: There are a number of errors in the document such as saying that the North Waste Dump was moved when it was not and also leaving the impression that moving the waste dumps and plugging the adits has taken care of the problems.
RESPONSE: We have omitted the North Waste Dump from our list of waste piles that have been moved. Moving the waste dumps and plugging the adits are part of EPA's remedy for the site. The remedial actions have not been completed; there are still some wastes that will be relocated to the mine pit area, and there will be further revegetation (personal communication with the EPA Remedial Project Manager on June 12, 1997). Some water from the Cropsy footprint is still being treated, and remedial efforts are continuing. Plugging the adits has reduced metal loading to surface water.
COMMENT: In reaching its conclusion that the Summitville site represents no apparent public health hazard, the PHA relies on data primarily obtained in 1993....PHA should be updated to include the 1994-96 data. Maybe some of the conclusions would change.
RESPONSE: The PHA did include surface water data through November 1995, and conclusions reflected those data. The document contains repeated mentions of the years supporting data were collected. This version of the PHA includes information on the 1995 studies on ducks and sheep.
COMMENT: Although ATSDR considers Summitville to present no apparent public health hazard, further sampling of heavy metals in surface water is recommended. What are the metals? A specific list would be nice. And how about pH?
RESPONSE: The metals listed in Tables 1 and 2 are the primary ones coming from Summitville drainages. We recommend that future analyses of environmental media address those metals and the pH of the media. Other metals could also be analyzed depending on the purpose of the investigation.
COMMENT: Drinking water wells along the river should be tested regularly. Crop, livestock and soil studies should also be continued, although ATSDR might argue that these don't apply directly to human health.
RESPONSE: The most recent private well sampling, completed in June 1995, did not show any metals exceeding drinking water standards except in one control well not influenced by Alamosa River water. ATSDR didn't recommend continued routine monitoring because previous testing during years when metal loading was high didn't indicate that wells were being influenced. However, we have added a recommendation that private wells be tested again to confirm the 1995 private well data. The PHA states our support for continuing studies on metal uptake by crops and metals in soils as well as for surface water analyses. Livestock studies are continuing.
COMMENT: Did adit plugging really "reduce" acid mine drainage from the site?...
RESPONSE: The volume of water being released from the site has been substantially reduced, therefore reducing the loading of metals to the Alamosa River. However, the concentrations of metals, as you pointed out, have not necessarily decreased. The concentrations will tend to increase during low flow conditions.
COMMENT: There's a contradiction on page 5 as to whether Jasper is 17 or 7 miles downstream from the mine.
RESPONSE: The 17 miles is the distance to Terrace Reservoir, and the 7 miles is the distance to Jasper, the nearest community. The document has been changed to clarify the distances.
COMMENT: ATSDR incorrectly assumes that the Alamosa River between Stunner campground and Terrace does not sustain agricultural crops or livestock.
RESPONSE: This statement has been deleted.
COMMENT: What specific drainages are being referred to when ATSDR states "Fish in some Colorado drainages include brook trout, etc ?" Also, which specific stream reaches would it be difficult to get fish to return to even if acid mine drainage from Summitville was eliminated?
RESPONSE: In the first question, ATSDR was not referring not to specific drainages but to fish found in Colorado rivers and streams in general. If drainage from Summitville were eliminated, it might be difficult to reestablish fish in the Alamosa River downstream of the mine site from Wightman Fork to a location above its confluence with Fern Creek because of drainage from Bitter, Alum and Iron Creeks. However, the Use Attainability Assessment (UAA) and future modeling efforts may help us determine which river segments would likely experience reestablishment of fish and when.
COMMENT: The statement is made that EPA's remedial actions have reduced the amount of metals and "other contaminants" entering surface waters. This may not be true for the metals. And how about hydrogen (H+) ions? What are those "other" contaminants?
RESPONSE: As explained in an earlier response, the volume of water being released from the site has been substantially reduced, therefore reducing the loading of metals and hydrogen ions to the Alamosa River. The other contaminants that we were referring to included cyanide and cyanide compounds.
COMMENT: ATSDR states "EPA continues to dewater and detoxify the heap leach pad." They've discontinued this.
RESPONSE: Noted. We have deleted this statement.
COMMENT: In discussing actions taken at the mine, there's no mention of the incomplete job and lingering pollution problems at the Cropsy footprint. Uncontrolled acid mine drainage from Cropsy cancels out gains made elsewhere at Summitville. EPA apparently does not consider the Cropsy footprint a part of the mine site (see Appendix B, UAA). If ATSDR bought into this scam, then many of the assumptions stated in this PHA are erroneous.
RESPONSE: Water from the drainage ditch at the base of the former Cropsy waste pile is routed to Cropsy Creek and isn't treated. Although the majority of acid-generating material has been removed, some residual flushing of mineral salts occurs. This flushing adds to the metal loading coming from the Summitville Mine site. This year, as part of the remedial effort, EPA is going to apply lime to the Cropsy valley followed by top soil and grass seed (personal communication with the EPA Remedial Project Manager, 6/20/97). This remedial measure may help to lessen the metal loading coming from this source.
COMMENT: What's the vegetative cap the PHA refers to on top of the mine pit?
RESPONSE: Although some test vegetation plots have been established, revegetation will take years. Therefore, we have eliminated this statement.
COMMENT: The first paragraph under the subsection "River Water" is confusing.
RESPONSE: We have rewritten the paragraph to make it more readable.
COMMENT: Drinking water standards are discussed, but not exceedances of agricultural use standards. These exceedances could impact human health, too.
RESPONSE: The Colorado Surface Water Agricultural Use Standards are standards for surface waters that are suitable or intended to become suitable for irrigation of crops usually grown in Colorado and that are not hazardous as drinking water for livestock.(2) Based on July 1995 irrigation water samples, the only metals exceeding the agricultural use standards are copper and manganese. Both of these metals may be mobile in Terrace Reservoir irrigated fields. Therefore, future environmental studies should consider both metals. Although a human health impact is unlikely, there should be evaluation of additional information on the metals' effects on livestock because livestock are more likely than humans to experience exposure to metals from multiple sources. Some livestock, for instance, drink water directly from the Alamosa River and eat feed containing elevated metals. The section on livestock contains information on situations in which concentrations exceed maximum tolerable levels for metals in feed and on the available information on metals in crops.
COMMENT: ATSDR assumes most fields receiving irrigation water from the Alamosa River are alkaline. ....Though this might be true for other parts of the San Luis Valley, it's not necessarily so for the Alamosa River watershed.
RESPONSE: Noted. The statement has been deleted.
COMMENT: Hydrogen (H+) ions are not mentioned as a contaminant from the Summitville Mine in the second paragraph on page 17.
RESPONSE: Reference to acidic waters has been added to the paragraph. Acid mine drainage is mentioned throughout the document.
COMMENT: ATSDR assumes remedial actions have improved downstream water quality and therefore shallow wells are safe.
RESPONSE: We have added a recommendation to continue remediation at the mine site and for additional sampling of private wells.
COMMENT: Livestock were eliminated as an exposure pathway. This may be premature. How about human consumption of big game animals that drink from the river and/or consume plants that receive water from the river? This potential exposure pathway is not discussed.
RESPONSE: In this version of the PHA, we have changed the eliminated exposure pathways of fish and livestock to potential exposure pathways. Big game animals, such as deer, may be exposed to metals in the environment at locations such as the area near Terrace Reservoir. No exposure data on large game animals near Summitville Mine were available for our review. However, our analysis would run similar to that presented for livestock, which we have identified as a potential exposure pathway.
COMMENT: In the last paragraph of the report, ATSDR says it supports continuing studies on metal uptake in crops. How about livestock? How about soils?
RESPONSE: The PHA emphasizes crops because they are a more direct pathway for
human exposure. The PHA contains evaluations of livestock and soils pathways, judging
them unlikely to have negative impacts on human health. However, we have added
statements supporting studies in most environmental media impacted by the Summitville
Mine.
1. Sheldon, T.B. Interpreting Drinking Water Quality Analysis, What Do the Numbers Mean? Rutgers Cooperative Extension, The State University of New Jersey, Rutgers. E185.
2. Erdman JA, Smith KS. Impact of the Summitville Mine on irrigation water, agricultural soils, and alfalfa in the southwestern San Luis Valley, CO. United States Geological Survey open file report 93-616. 1993.
