PRELIMINARY PUBLIC HEALTH ASSESSMENT
WILLIAMS PIPE LINE COMPANY
SIOUX FALLS, MINNEHAHA COUNTY, SOUTH DAKOTA
- Table 1 - Contaminants of Concern in On-Site Soils
Table 2 - Contaminants of Concern in On-Site Water
Table 3 - Contaminants of Concern in Off-Site Soil
Table 4 - Contaminants of Concern in Off-Site Water
Table 5 - Contaminants of Concern in Ambient Air
Table 6 - Completed Exposure Pathways
Table 7 - Potential Exposure Pathways
Table 8 - Estimated Population for Completed and Potential Exposure Pathways
Table 9 - Comparison of Estimated Exposure Dose to Health Guidelines
Appendix C - Response to Public Comments
C.V. = Comparison Value
* after value indicates the value is estimated.
NA = not analyzed, ND = not detected, RD= rejected data
All samples are from the north side of the site.
References for tables are found at the end of Appendix tables.
Notes:
C.V. = Comparison Value
* after value indicates the value is estimated.
NA = not analyzed, ND = not detected, RD= rejected data
(N) or (S) before value indicates samples taken on the North or South side of WPL property. Ifnot indicated sample is from the north side of the site.
References for tables are found at the end of Appendix tables.
| Chemical | Off-site soil mg/kg | Year of sample/ reference | C.V. | C.V. Source |
|---|---|---|---|---|
| arsenic | 2.3-4.3 | 87/E&E | 0.6 | RfD |
| lead | RD | 87/E&E | none | none |
| mercury | .4-.6 | 87/E&E | none | none |
C.V. = Comparison Value
* after value indicates the value is estimated.
NA = not analyzed, ND = not detected, RD= rejected data
All samples are from the north side of the site.
References for tables are found at the end of Appendix tables.
Notes:
C.V. = Comparison Value
* after value indicates the value is estimated.
NA = not analyzed, ND = not detected, RD= rejected data
(N) or (S) before value indicates samples taken on the North or South side of WPL property. Ifnot indicated sample is from the north side of the site.
References for tables are found at the end of Appendix tables.
Notes: C.V stands for Comparison Value
NA = not analyzed, ND = not detected.
CREG = cancer risk evaluation guide, RfC = reference concentration
References for tables are found at the end of the Appendix tables.
Note:
* The acute MRL of 0.002 ppm for benzene was converted to mg/m3 by multiplying 0.002 by3.25, which is the conversion factor listed for benzene in the NIOSH Pocket Guide to ChemicalHazards (1990).
| CDC | Centers for Disease Control |
|---|---|
| CREG | Cancer Risk Evaluation Guide for environmental media |
| C.V | Comparison Value |
| EMEG | Environmental Media Evaluation Guide established by the Agency for Toxic Substancesand Disease Registry |
| EPA AL | U.S. Environmental Protection Agency Action Level for lead in drinking water |
| IMRL | Intermediate Minimal Risk Level established by ATSDR |
| LTHA | Lifetime Health Advisory established by the Environmental Protection Agency |
| MCL | Maximum Contaminant Level established by the Environmental Protection Agency |
| MRL | Minimum Risk Level established by the Agency for Toxic Substances and DiseaseRegistry |
| N | North |
| NA | Not Analyzed |
| ND | Not Detected |
| PMCL | Proposed Maximum Contaminant Level established by the Environmental ProtectionAgency |
| RD | Rejected Data |
| RfD | Reference Dose established by the Environmental Protection Agency and used to develop the RfD comparison value |
| S | South |
| WPL | Williams Pipe Line |
| 1.0E-6 | This is an abbreviation for 1 X 10-6 or 0.000001 |
COMMENTS RECEIVED ON THE WILLIAMS PIPE LINE TWELVE STREET TERMINAL PUBLIC HEALTH ASSESSMENT
The Williams Pipe Line Twelfth Street Terminal Public Health Assessment was available forpublic review and comment from March 25, 1992 through April 23, 1992. The Public CommentPeriod was announced in local newspapers. Copies of the public health assessment were madeavailable for review at the Sioux Falls Main Library, and the Sioux Falls office of the SouthDakota Department of Environment and Natural Resources. In addition, the public healthassessment was sent to 7 individuals or organizations who had requested that they receive copies. Thirty-one comments were received from three organizations. Two of these organizations madea combined response.
Comments and responses are summarized below. The page numbers referred to in the commentsare from the Public Comment Release and thus may not match those in this document. Thecomment letters can be requested from ATSDR through the Freedom of Information Act.
| COMMENT 1: | Contrary to the suggestions in the Preliminary Health Assessment (PHA)report, the extent of the petroleum and nitrate that originated from the site has been defined,controlled, and is being successfully remediated. |
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RESPONSE:
The public health assessment contains no positive or negative evaluation of site remediationactivities. ATSDR did conclude that the extent of contamination had not been completelyidentified.
| COMMENT 2: | The PHA report was critical of the fact that the pesticide contaminationassociated with the burn pit had not yet been remediated. Anyone familiar with the Superfundprocess should know that EPA will not allow such activity to occur until the RI/FS process iscompleted. |
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RESPONSE:
In Site Visits portion of the Background section of the public health assessment, the followingobservation is made about a March 1991 visit to the site by Dr. Robin Brothers, "No furtherremedial activities had taken place on the burn." This is an observation not a criticism. Incidentally, the same section also describes a 1990 site visit by ATSDR and EPA staff whereWilliams Pipeline staff demonstrated the interceptor trench and treatment facilities being used toremediate groundwater contaminated by the burn pit. EPA does allow remediation activitybefore the RI/FS is completed.
| COMMENT 3: | The commenter was concerned that the public health assessment described anumber of health hazards not related to the site including arsenic. |
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RESPONSE:
A public health assessment describes the possible health impact of the contaminants identified,no matter what the source.
| COMMENT 4: | It would appear that the authors of the report chose not to access all theextensive and most pertinent data that is available for this site. |
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RESPONSE:
The public health assessment cites only those documents actually used. ATSDR searched thefiles for this site at EPA and the Sioux Falls office of the South Dakota Department ofEnvironment and Natural Resources with the expectation that these files would be the mostcomplete.
| COMMENT 5: | The public health assessment unnecessarily duplicates the efforts being made bythe State and EPA. |
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RESPONSE:
The Superfund law and its amendments require that ATSDR evaluate the possible health impactof each site proposed for the National Priorities List (NPL) through the development of a publichealth assessment. The efforts of EPA and the State are legislatively mandated towards thecleanup of the site, not the evaluation of health impact.
| COMMENT 6: | The public health assessment is complicated and confusing because it considersthe whole facility instead of just the burn pit, and, therefore, may evoke unnecessarily communityanxiety. |
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RESPONSE:
ATSDR decided to evaluate the whole facility because the actual sources of the contaminantshave not been fully identified, and because of the community concerns about the HaywardSchool incident.
| COMMENT 7: | The boundaries of the study area and the specific population at risk were not adequately identified in the public health assessment. |
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RESPONSE:
The public health assessment has been revised to provide this information.
| COMMENT 8: | The relationships between sources, the extent of contamination, and thepotential exposure pathways need to be better elucidated |
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RESPONSE:
The Pathways Analyses section has been revised to address this concern.
| COMMENT 9: | The summary should state the private home and the old Hayward school aredemolished and the lots are level. |
RESPONSE:
The summary of the public health assessment has been revised to include this information.
| COMMENT 10: | The discussion of the potential exposure of children to contaminated soilshould be expanded to include where the exposure might occur and who else might be at risk. |
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RESPONSE:
This discussion was deleted as part of an extensive revision of the public health assessment. Itwas the evaluation of the health assessor (John Crellin) doing the revision that the data, currentlyavailable, does not support the existence of this pathway.
| COMMENT 11: | The statement about the levels of increased arsenic in the municipal watersupply being a cancer risk, should be balanced by the fact that these levels are considered to bebackground. Further, it should be stated that these levels are below EPA's drinking waterstandards. |
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RESPONSE:
The public health assessment has been revised to delete this discussion.
| COMMENT 12: | The summary should state how many of the contaminated wells are still beingutilized. It should also state that users of contaminated wells should receive informationconcerning the contamination. |
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RESPONSE:
The summary has been revised to include the number of contaminated wells.
| COMMENT 13: | The levels of hexane, benzene, and pentane in the old Hayward School and a residence should be identified. The fire and explosion risks are negligible with the removal ofthe two structures. |
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RESPONSE:
The levels of hexane, benzene, and pentane are described in the Environmental Contaminationand Other Hazards section. The summary does not say that there are fire and explosion risks; itonly states that this is community health concern.
| COMMENT 14: | A list of the hazardous substances and their location on the site would give a clear picture of what the report is to encompass. |
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RESPONSE:
This is done in the Environmental Contamination and Other Hazards and Pathways Analyses section.
| COMMENT 15: | The background information does not list the petroleum leak near the loading rack area in October 1983. |
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RESPONSE:
This information can be found in the first paragraph of the History of Contamination portion ofthe Background section.
| COMMENT 16: | The third paragraph of the Site History should include information that theburn pit was built into the regional groundwater table and product accumulated from tankcleaning and an oil water separator. |
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RESPONSE:
This is done in the fourth paragraph of the History of Contamination portion of the Background section.
| COMMENT 17: | The fifth paragraph of the Site History should mention that tank 1341 was thecause of the spill. |
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RESPONSE:
This is already done.
| COMMENT 18: | The History of Contamination section should describe the court case on thepipeline leak at the northeast part of the site in 1969. It should also mention the vapors foundwhen sewer line were put in place. |
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RESPONSE:
This section is not intended as an all-inclusive summary.
| COMMENT 19: | The fourth paragraph should be revised to indicate that EPA, not the SouthDakota Department of Wildlife and Natural Resources, have concluded that pesticides wereprobably also dumped in the burn pit. |
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RESPONSE:
The public health assessment has been revised to make this change.
| COMMENT 20: | In the Remedial Activities section, there is no mention of other off-site releasesnear the facility and how they relate to the problems at the facility. |
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RESPONSE:
This information is described elsewhere in the public health assessment.
| COMMENT 21: | The Environmental Contamination and Other Hazards section should include a better identification of the potentially affected population and off-site boundaries. |
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RESPONSE:
The Pathways Analyses section has been revised to include this information. It is not appropriatefor inclusion in the Environmental Contamination and Other Hazards section.
| COMMENT 22: | The first paragraph of the Municipal Well Pathways section identifies arsenic as a ubiquitous contaminant in the Sioux Falls area. This should also be mentioned in thediscussion of the "increased risk of cancer from arsenic. |
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RESPONSE:
The Municipal Well Pathways section and the discussion of the carcinogenicity of arsenic havebeen deleted.
| COMMENT 23: | The statement in the second paragraph of the section titled Soil and Burn PitSludge, "Soil sampling across the site did not reveal significant soil contamination" appears toconflict with "A significant data gap exists concerning the extent of on-site soil sampling. Moston-site soil samples were collected from the area around the burn pit." |
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RESPONSE:
The public health assessment has been revised to remove this apparent conflict.
| COMMENT 24: | There appear to be a conflict between question 8 which identifies private well-water users at a high increased risk to cancer and question 9 which states that the safety ofprivate wells can not be established, because the extent of contamination is not fully determined. |
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RESPONSE:
The responses to those two questions have revised to resolve this apparent conflict.
| COMMENT 25: | The conclusion that high levels of arsenic in municipal and private water, andsoils may pose a health threat should include a explanation of the threat for each media. TheConclusion section should also state that the arsenic levels are naturally occurring. In addition,there should be mentioned that ATSDR's conclusion about the health risk from arsenic in themunicipal water supply is inconsistent with the EPA Drinking Water Standard. |
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RESPONSE:
Nearly all the discussions of arsenic have been removed from the public health assessment,because the arsenic present in the Sioux Falls public water supply is considered to be naturally-occurring and not site-relate. However, ATSDR's conclusion in the public comment release thatthe arsenic levels (maximum concentration of 17 ppb) in the Sioux Falls water supply mayrepresent a health risk is not inconsistent with EPA's drinking water standard of 50 ppb. Thefollowing discussion is based on a review of information in ATSDR's Toxicological Profile forArsenic and EPA's Integrated Risk Information System (IRIS).
EPA's drinking water standards, also known as Maximum Contaminant Levels (MCLs) are notbased solely on health guidelines. A MCL will often be greater than the health guideline for thechemical if it is not technologically feasible to remove the contaminant down to the healthguideline. The MCL also may be greater than the health guideline if it is not possible toanalytically detect the chemical at the guideline level.
ATSDR bases its conclusions solely on health guidelines. In the case of arsenic, ATSDR usesEPA's oral reference dose to calculate drinking water comparison values of 3 ppb for childrenand 11 ppb for adults. No cancer slope factor is available for arsenic, a known humancarcinogen, so a comparison value based on carcinogenicity can not be calculated. Exceeding acomparison value do not necessarily indicate the level found is a health hazard. Furtherevaluation is necessary.
The maximum concentration of arsenic for the Sioux Falls water supply, 17 ppb, is somewhatgreater than as the no observed adverse effect level (NOAEL), 9 ppb, in the humanepidemiological study on which EPA's RfD is based. However, it is 10 times lower than thelowest observed adverse effect level (LOAEL), 170 ppb, in that same study. The question is,therefore, where do health effects begin? This can not be answered definitively, so it is thepractice of ATSDR in these situations to say that there is some health risk.
Incidentally, EPA is currently reviewing its MCL for arsenic of 50 ppb and it is expected that therevised MCL will be lower.
| COMMENT 26: | The report identified several areas where data were not available or wereseverely limited, such as surface-soil, ambient air data, and contaminant level of private wells,yet the report identified the site as a public health hazard in the conclusions. It is also valuableto distinguish the extent of a public health hazard for both on- and off-site areas. |
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RESPONSE:
The Conclusions section has been revised to incorporate these suggestions.
| COMMENT 27: | The report leaves some unanswered questions for the reader. What shouldfollow this report? How are the recommendations to be carried out? Who is the appropriateagency to do the follow-up studies? Is there funding available for additional studies? |
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RESPONSE:
The Recommendation section has been revised to identify EPA as the agency responsible toimplement the NPL-related recommendations.
| COMMENT 28: | Recommendation 10 (cease/reduce exposure) states that childcare facilities inthe area should use municipal water for all purposes. An explanation of this recommendationwould clarify its need. How many childcare facilities are there? How many of these are not onmunicipal water? |
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RESPONSE:
This recommendation has been deleted. Based on the information reviewed in this public healthassessment, it is unlikely that the soil or drinking water at this facility are contaminated with site-related substances. There is no evidence of off-site soil contamination on the south side of WPL. This faculty is probably on public drinking water. While the exact location of this day carefacility is not known, it is not located in the area of known groundwater contamination.(5) Nosamples were taken in areas designated as childcare centers.
| COMMENT 29: | Recommendation 11 (cease/reduce exposure) states that institutional controlsfor the Skunk Creek aquifer preventing future development of this aquifer be implemented. Anexplanation of this recommendation would clarify its need. Is it in reference to the entire aquiferor that portion affected by contamination? |
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RESPONSE:
This recommendation has been deleted.
| COMMENT 30: | Recommendation 2 on site characterization states sampling municipal water atthe tap should be done. An explanation of this recommendation needs to list the area to besampled and frequency and the reason for the sampling. |
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RESPONSE:
This recommendation has been deleted.
| COMMENT 31: | Recommendation 5 on site characterization states soil sampling in areassurrounding the WPL site and schools in the area should be done. An explanation of thisrecommendation would clarify its need. What areas and parameters should be sampled? |
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RESPONSE:
The Recommendation section has been revised (see page 36) to indicate that EPA, SDDWNR,and ATSDR should work cooperatively to determine what additional sampling should be done.
1. The National Toxicology Program in its Annual Report on Carcinogens classifies a chemicalas a"known human carcinogen" based on sufficient human data. Its classification of a chemicalas being "reasonablely anticipated to be a carcinogen" is based on limited human or sufficientanimal data.
2. IARC defines a class 1 carcinogen as a substance which studies in humans indicate a causalrelationship between the agent and human cancer. Class 2 carcinogens are those reasonablyanticipated to be carcinogens. For a 2A classification, there is limited evidence ofcarcinogenicity from human studies which indicate that a causal interpretation is credible, but notconclusive. A classification of 2B indicates that there is sufficient evidence of carcinogenicityfrom studies in experimental animals.
3. In EPA's classification scheme, a chemical is considered a class A or human carcinogen basedon sufficient evidence from studies of humans. A substance is considered class B1 if there islimited evidence from human studies. B2 is used when evidence for carcinogenicity isinadequate or non-existent based on human studies, but sufficient based on animal studies.
4. This is based on an extensive drive-through of the area south of WPL by Dr. John Crellin in1990.
5. This is based on an extensive drive-through of the area south of WPL by Dr. John Crellin in1990.
