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PUBLIC HEALTH ASSESSMENT

BAY CITY MIDDLEGROUNDS
BAY CITY, BAY COUNTY, MICHIGAN

RESPONSIVENESS SUMMARY

The MDPH released a draft of this Public Health Assessment for public comment on January 31, 1996. The initial public comment period lasted until March 1, 1996, and a second comment period was provided from March 14, 1996, to April 15, 1996. MDPH/MDCH(22) received comments from a representative of the City of Bay City (a Potentially Responsible Party [PRP] for the site) and from an engineering firm representing a group of other PRPs for the site (Reference 5). Their comments and MDCH responses are listed below. The page numbers listed are those in the reviewed draft, and do not necessarily correspond to the current version.

MDCH also received many comments concerning the site from residents of Middleground Island and Bay City. None of these comments addressed the content or format of the draft assessment. Those comments that reflected health concerns regarding the site are addressed in the appropriate section of the assessment.

Comments from a City of Bay City representative

1A. Forward, second paragraph – Why was the Health Assessment completed since the Landfill is not on the National Priorities List? Although the EPA and MDEQ had proposed to place the site on the list, the landfill was never actually listed.

Response: Under the relevant laws, the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, and the Superfund Amendment and Reauthorization Act (SARA) of 1986, as amended, a health assessment is to be completed for each site proposed for the National Priorities List (NPL) within one year of the proposal. The health assessment process begins with the proposal, and continues independently of the process of placement on the NPL. The process for NPL placement of the Bay City Middlegrounds Landfill site has been delayed for several reasons, and this Public Health Assessment has reached completion before the final decision on the site status has been made. Other toxic waste sites have had Public Health Assessments written even though the sites were ultimately rejected for placement on the NPL.

2A. Page 1, second paragraph, third sentence – In 1974, how many or how much of the trenches and original pits were covered by the five-foot cap, and how accurate are the data that are being used? Please provide documentation of how the data was derived. If it is accurate, then a map delineating this information would be useful in the site's investigation and remediation.

Response: MDCH used the figure provided by Ms. Susan Kaelber-Matlock of MDEQ for the uncapped area of the landfill. MDCH understands that this figure is an estimate based on the experience of investigators attempting to locate the extent of the landfill. MDCH has no primary data to make an independent evaluation of this figure.

3A. Page 1, fourth paragraph, second sentence – None of the residents of the island are connected to the Bay City municipal water system. They are connected to the Bay County Water Supply System.

Response: Thank you for the information, and the assessment has been changed to reflect the actual situation.

4A. Page 3, fourth paragraph, first and second sentences – How accurate is the one-third figure that allegedly was not capped? Further detail is needed to confirm pathways of exposure. According to Ms. Susan Matlock the capping extent is merely a guess.

Response: See our response to Comment #2A.

5A. Page 4, first paragraph – How accurate is the statement that leachate is seeping out of the mound and flowing into the ditches? Having been with the City for four (4) years, and having been involved in all activities associated with this landfill, I have never observed this phenomenon or recall seeing proof of this event taking place. Once again, documentation would be appreciated verifying these discharges. Ms. Matlock said that she had never personally observed these discharges at a recent meeting with Matt Zimmerman, Bay City's environmental attorney, the PRP attorney for G.M., and myself.

Response: MDCH reported what has been reported to us by MDEQ staff, Island residents, and other sources.

6A. Page 4, fifth paragraph – Reference is made to a Health Consultation that was prepared in 1994 by the Michigan Department of Public Health. The City would appreciate receiving a copy of that document to complete its records as we do not have a copy. I also contacted Ms. Sue Matlock, the DEQ project coordinator for the Middlegrounds, and she does not have a copy of this document either.

Response: MDCH has sent the commentor and Ms. Matlock copies of the consultation.

7A. Page 6, sixth paragraph – The contaminants of concern were analyzed based upon one case of cancer per one million persons exposed, obviously using the Federal criteria. Michigan criteria is different, and since the site is not on the NPL, wouldn't Michigan's standard be more applicable?

Response: The assessment uses ATSDR criteria, because the site was proposed for the NPL.

8A. Page 7, third paragraph – The Toxic Chemical Release Inventory referred to in this paragraph appears to be vague on the subject of contributors to the problems at the landfill. The EPA spent a great deal of time recently reviewing records and generating data on possible contributors to the contamination at the Middlegrounds Landfill. Why weren't these volumes of data accessed for this report?

Response: ATSDR suggests that health assessors search the U.S. EPA's Toxic Chemical Release Inventory (TRI) to identify chemicals that might be present in the environment around the site due to the operations of other industrial facilities in the site vicinity. The TRI also includes data on transfer of chemicals to disposal facilities, but, as mentioned in the text, the BCM landfill was closed three years before the TRI began collecting data. There are limitations to the TRI data, in that facilities are only required to file reports if they handle more than specified amounts of specified chemicals and the amounts released are reported as annual totals, frequently as estimates within rather wide ranges. The U.S. EPA search was meant to identify PRPs for cost recovery purposes. The source of environmental contamination in the site area is less important to the health assessment process than the presence of the contaminants.

9A. Page 12, first paragraph – Although the Middlegrounds landfill is singled out in this report as the only source of PCBs on the river system, it should be noted that other locations have been identified up and down the Saginaw River that have high concentrations of PCBs that are actually in the river. Note should also be made of data collected by two contractors completing a remedial investigation and an expanded site investigation, who collected river samples adjacent to the landfill on two different occasions. The conclusion was "None of the concentrations found are considered to be of human health concern," as per the following paragraph of the report.

Response: According to Susan Kaelber-Matlock of MDEQ, the BCM landfill is "a", if not "the", major remaining source of PCBs to the lower stretch of the Saginaw River. The assessment has been revised to make it more clear that there are other potential sources. Because PCBs are nearly insoluble in water and readily bioaccumulate, there can be impacts on the food chain and the general ecology at concentrations in the water that pose no risk to human health from direct consumption.

10A: Page 15, fourth paragraph – Makes reference to Table # 3 regarding the leachate from the landfill. The Risk assessment that I received at the MDEQ meeting regarding this issue contained no Table # 3. I would appreciate receiving a copy of this table so that my report is complete.

Response: Our apologies that you received an incomplete copy of the Health Assessment. We have sent you a complete copy.

11A. Page 21, third paragraph – A discussion of PCBs in and around the site almost dismisses the possibility of cancer being contracted by humans from this landfill. Yet the conclusions hardly reflect this attitude by saying "The Bay City Middlegrounds Landfill site poses a public health hazard." The conclusions of a report should always reflect the content of the document, and not be at odds with it as in the Public Health Risk Assessment.

Response: There are other potential health hazards on the site than cancer caused by exposure to PCBs. The assessment has been revised to better clarify the health concerns associated with the designation of the site as a "public health hazard".

Comments from an engineering firm representing a group of PRPs for the site:

General Comments

1B(g). The definition of the "Site" needs to be clarified within this document. It appears that the Site is defined within this document to consist of not only the mounded refuse area and the former engineered trenches (the Site as the PRP group defines it), but also the dredge spoil area located to the north of the Site, as well as other areas which may be located on Middleground Island. Much of the analysis appears to be focused at the dredge spoil area located to the north of the Site. Also, the document focused on the small contaminated area located in the vicinity of Monitoring Well #8 (MW-8) and does not appear to characterize the entire Site based on site-wide constituent concentrations.

Response: MDCH considered the site to be the entire property owned by the City of Bay City including the former Middlegrounds landfill and the sediment settling basin north of the landfill. This has been made clear in the assessment. Data collected from other areas near the site is included in the "Off-site contamination" section. ATSDR Public Health Assessments attempt to address all potential public health impacts from environmental contamination in the vicinity of the site that is being assessed without regard to the source of the contamination. As a conservative approach, MDCH follows ATSDR guidelines to evaluate the health hazards based on the maximum concentrations of contaminants of concern found on the site.

2B(g). The conclusions and recommendations sections are not supported by the data analysis and other site-specific information contained within the document. The body of the report indicates/suggests that this Site presents relatively few concerns from a human health perspective. However, the conclusions and recommendations sections support actions which are not warranted based upon the assessment. For example, Conclusion #1 states that "The Bay City Middleground Landfill Site poses a public health hazard. Surface soil, groundwater, and river sediment at and near the Site are contaminated with metals, pesticides, and volatile and semi-volatile organic chemicals." This statement does not seem to be supported by the document which:

  1. Determined "exposure to soil on the Site is not likely to be sufficient to cause adverse health effects."
  2. Identified only manganese from on-site ditches as a potential health concern. The potential for this exposure pathway to be completed along with the significant daily ingestion rate required to generate potential risk is highly unlikely.
  3. Cannot identify any PCB discharge to the river based on existing hydrogeological information. As a result, the various fish consumption discussions are not relevant within the context of Middleground Landfill since the Site's contribution to the river, if any, is unknown.

Response: Because of the chemical contamination present on the site and the potential for past and future exposure, the site poses a public health hazard even though the current exposure vis some pathways is estimated not to be of significant human health risk. PCBs are present at the landfill at very high concentrations in an organic chemical layer in contact with the groundwater. There is no evidence of any barrier to groundwater flow between the area where PCBs were found and the river. Furthermore, Saginaw River sediments adjacent to and downstream of the site appear to contain more PCBs that those upstream of the site.

Specific comments

1B(s). Summary, first page, third paragraph - The statement that organic chemicals including PCBs have been found in the soil and groundwater is somewhat misleading. PCBs have not been detected in any surface soil samples obtained from the approximately 25 acre parcel which encompasses the mounded refuse area and the former engineered trench locations. Sampling from the dredge spoil area, located to the north of the Site, had detected low levels of PCBs up to 0.9 ppm in surface soils. This area is not considered part of the Site. In addition, the PCBs and high concentrations of other organics detected in groundwater and soils are restricted to a relatively small area in the vicinity of MW-8 and are not necessarily indicative of site-wide contamination. Furthermore, the statement that surface soil at the landfill contains elevated concentrations of PAHs is contrary to statements made on pages 9-11 that the concentrations of PAHs in the surface soil and shallow subsurface soil are found at concentrations typical of urban soils. The statement that "Some fish living in the Saginaw River contain high concentrations of PCBs, from the BCM site..." is without support. No evidence has been collected to date which documents that PCBs are being released to the Saginaw River from the Site. Also, PCBs were not detected in leachate, surface soil, or drainage ditch samples taken from the Site, eliminated this exposure pathway to Saginaw River fish. PCBs were detected in subsurface soil and groundwater collected from the MW-8 area, but there is no direct evidence that groundwater from this relatively small area is discharging to the River.

The available surface water samples collected from the Saginaw River, as presented in the assessment, are not sufficient to discern sources. As the assessment states, there are multiple sources potentially contributing PCBs to the Saginaw River in the vicinity of the Site. The maximum PCB concentration reported to be associated with sediments in the Saginaw River is a P-Qualified value of 0.87 ppm reported in Table 13 (there is no footnote in the Table to explain the qualifier). This is below the clean-up objective of 1 ppm or higher commonly targeted for sediment remediation in river systems.

Response: MW-8 is located approximately 50 feet from the river bank. There is no indication in the available hydrogeological data of any substantial barrier to groundwater flow between the well vicinity and the river. We agree that the available data is not sufficient to identify the sources of PCBs in the river. ATSDR Public Health Assessments attempt to evaluate all potential public health impacts in the vicinity of Superfund sites regardless of the source of the impacts. Because of the possibility of bioconcentration of PCBs, there is concern for ecological and human impacts from low concentrations of the chemicals in sediments.

2B(s). Summary, first page, last paragraph - The statement, "The BCM site poses a public health hazard under current conditions," is not justified by the facts presented in the body of the assessment. The "Summary" implies that the main paths by which exposure is hypothesized to occur include consumption of PCB-contaminated fish, contact with on-site surface soil, and contact with leachate and drainage ditches.

With respect to fish consumption: 1) There is no direct evidence of PCB discharge from the landfill area to the river. 2) The maximum concentrations of PCBs in skin-on walleye fillets (the sport fish people are most likely to catch and consume) are below the MDPH's level of concern of 2 ppm. 3) There is no evidence to show, and it is unlikely, that people consume 16.7 grams of walleye from this stretch of the river on a daily basis (assumption made on p. 27). 4) As stated on page 27 of the assessment, people are unlikely to consume enough walleye to exceed ATSDR's MRL for PCBs or to exceed an acceptable cancer risk. 5) Nobody is likely to eat carp (a non-game fish) since many types of game fish are available in the area which are more desirable for human consumption. 6) Both carp and walleye are migratory, and, as stated in the assessment, there are multiple off-site sources for PCBs along this stretch of river making it extremely difficult to conclude what portion of PCBs, if any, came from Middleground Landfill. 7) To date, the available studies which have attempted to link fish consumption with an adverse health effect due to PCBs have been unable to show any adverse effect, or have been unable to demonstrate that PCBs alone caused an adverse outcome.

With respect to contact with surface soil: 1) as stated in the first complete sentence on the second page of the "Summary," "Exposure to the soil on the Site is not likely to be sufficient to cause adverse health effects." 2) The constituents detected in surface soil are primarily PAHs found at concentrations typical of urban settings and various inorganics which may not be site-related (see comment 6 for expansion on this point).

With respect to leachate and drainage ditches: 1) as discussed on page 27 of the assessment, the only constituent of interest detected in the water from on-site ditches was manganese, and children are unlikely to ingest enough water from the ditch to exceed an intake associated with an adverse health outcome; and 2) the amount of leachate a person would have to drink to incur adverse health effects from the constituents of interest detected (benzene, 1,4-dichlorobenzene, chromium, and nickel) would be 10 percent or more of that person's daily water ingestion rate. This is unlikely. It is important to note that while Site access is not completely restricted (fenced on three sides), the unfenced side is along the west branch of the Saginaw River, which would permit access only by boat or on those occasions when the river is frozen. Furthermore, it is important to note that the landfill was previously capped, reducing the potential for exposure to surface soils.

In summary, the public health assessment needs to clarify the difference between "hazard" and "risk". If by "hazard", the assessment means to imply the existence of conditions or chemicals which might, under the appropriate conditions of exposure, lead to "risk", then it should state so clearly. However, the more important indicator for public health would be estimates of "risk" defined as the probability of adverse health effects which could reasonably be expected to occur over the lifetime of an individual given the existence of hazards combined with estimates of exposure associated with reasonably foreseeable complete exposure pathways. This assessment provides no information which suggests the Site poses an unacceptable risk to human health.

Response: On the PCBs in fish in the Saginaw River: 1) There are PCBs in the groundwater at the Middleground Landfill within 50 feet of the river, and no evidence for any barrier to groundwater flow between the contaminated area and the river. Because PCBs bioaccumulate in the food chain, concentrations of the chemicals in water and sediment that cannot be easily detected by chemical analysis might contribute to contamination of fish living in the water. 2) There is considerable debate on whether the U.S. FDA Action Level of 2 ppm (used by MDCH) is adequately protective for consumers of sport-caught fish. Applying the protocol proposed by the Great Lakes Council of Governors Task Force(23) to the walleye data would limit consumption of the fish to one meal per month. 3) On the contrary, MDCH interviews with anglers and MDNR creel surveys do document consumption at the level cited. 4) Walleye is not the only fish anglers consume from the river. 5) The commentor's assertion is contrary to the evidence from MDCH interviews with anglers and MDNR creel surveys. 6) ATSDR Public Health Assessments attempt to address all potential public health impacts from environmental contamination in the vicinity of the sites being assessed, regardless of the source of the contamination. 7) Agreed, the epidemiological evidence for health effects in humans from consumption of PCB-contaminated fish is inconclusive, however, from the evidence of adverse health effects in animals exposed to PCBs, a conservative public health approach is to minimize human exposure to the chemicals.

On the question of on-site soil: A situation may present a hazard even if the best estimate for current exposure does not yield a significant risk. Past or potential future exposures may be significantly different. See also our response to Comment 6.

On the question of leachate and the ditches: The documented concentrations of contaminants of concern and the most likely exposure scenario do indicate that it is unlikely that anyone would suffer adverse health effects from exposure to the leachate or water in the ditches. However, there have been reports that the water in the ditches has been discolored, though the water was not sampled for analysis at those times.

On the question of existing restriction of access to the site: MDCH admits that the current site fence discourages trespass, but respectfully disagrees with the commentor as to the effectiveness of the fence. The fence does not reach the water, and it is possible to walk around either end of the fence into the site with at most a short wade in the river.

On the confusion of risk and hazard: The commentor has interpreted our use of the term "public health hazard" correctly. The further discussion in the assessment includes qualitative discussion of the risks related to the actual exposures to the contaminants at the site. ATSDR does not provide a category for a site that does not pose any significant risk under current conditions but might pose a significant public health risk under different possible exposure scenarios.

3B(s). Environmental Contaminants and Other Hazards, page 6 - This is a document for public release. As such it should define the various comparison values used in the assessment to select "contaminants of concern" and should define for the reader the assumptions inherent in the derivation of each value.

Response: The definitions of the comparison values have been expanded in the revised assessment as the comment suggests.

4B(s). Page 7, Foot Note - The use of a pica child to assess potential exposure from soil ingestion is unreasonable and not supported by scientific data. As discussed in USEPA's 1995 draft "Exposure Factors Handbook," 1) pica behavior is believed by the scientific community to be abnormal and rare; and 2) the soil ingestion rate for pica behavior is based solely on the data for one child. Furthermore, the assessment states that the trespassing child is likely to be an older child, not a 2-to-5-year-old child who might display pica behavior. Also, since the Site is currently fenced on three sides [with limited access on the fourth side (river side)], trespassing by even an older child is unlikely, and thus, the exposure to Site constituents extremely limited.

Response: Comparison Values, used in the assessment to select contaminants of concern for further evaluation, are calculated based on an extreme exposure scenario so that no chemicals of potential hazard are omitted. In a later section of the assessment, a more realistic scenario is used to estimate the most likely health hazard.

5B(s). Page 8, Groundwater - "Contaminants of concern" in groundwater are selected on the basis of the detected maximum concentration of each chemical. Using maximum concentrations in this situation where high concentrations appear to be restricted to a small area of the Site is potentially misleading the reader to the conclusion that groundwater contamination is widespread and a general problem. This is not the case. Based on the lower concentrations and fewer constituents of interest detected in groundwater outside of the vicinity of MW-8, site-wide groundwater contamination should be considered and assessed separately from the "hotspot" associated with MW-8.

Response: There is no evidence in the hydrogeological information available that there is any barrier to groundwater flow between the "hotspot" around MW-8 and the rest of the aquifer. Hence, there is a potential for the contamination in the groundwater to spread.

6B(s). Surface Soil, page 9, third paragraph, last sentence - The use of shallow subsurface sampling as a basis for determining that listed inorganic constituents are site-related is inappropriate. The fact that the Site is in an urban/industrial area and that PAHs were detected at concentrations comparable to those found in urban settings suggests that many of the inorganics listed as "contaminants of concern" may also be typical of local background concentrations. The fact that these inorganics exceed ATSDR comparison values, particularly those based on pica behavior, is irrelevant as to whether these constituents are site-related or of concern to a typical hypothetical trespasser.

Response: ATSDR Public Health Assessments attempt to address all potential public health impacts from environmental contamination in the vicinity of the sites being assessed, regardless of the source of the contamination. It is therefore appropriate to evaluate "background" levels for potential human health impacts.

7B(s). Page 15, first paragraph, first two sentences - The statement is inaccurate and misleading. The only "contaminants of concern" identified in Table 4 are PAHs. While organic constituents other than PAHs were identified in the shallow subsurface samples shown in Table 10, only PAHs can be considered "contaminants of concern" based on the screening procedure used in the assessment. PCBs are not "contaminants of concern" because they were only detected at very low concentrations (less than 1 ppm) in shallow subsurface soils, below any screening value of concern.

Response: MDCH stands behind our consistent use of the procedure described on pages 6-7 of the Draft Public Health Assessment (pages 7-9 in this printing).

8B(s). Page 15, first paragraph - While the potential exists for snowmobilers and sledders to use the Site for recreational activities, potential exposure to constituents would be extremely difficult due to snow cover. Furthermore, exposure duration would be limited due to winter weather restricting the duration of human activities. The possibility of hunters using the landfill area is unlikely due to the marginal wildlife habitat. Observation of hunters were probably in the dredge spoil area, which is partially wooded and located to the north of the Site (by the PRP group's definition). Complete Site fencing, scheduled for 1996, will minimize the potential for future trespassing.

Response: See our response to General Comment 1B(g) above regarding the inclusion of the sediment settling basin (dredge spoil area) in the definition of the site. Thank you for the information about the plans for further fencing of the site. The information has been added to the assessment.

9B(s). Page 17, first paragraph - It is inappropriate to draw conclusion about potential exposure associated with site-wide groundwater based primarily on contamination apparently restricted to a small area of the Site.

Response: See our response to Comment 5B(s).

10B(s). Page 17, second paragraph - There is no clear evidence that groundwater in the vicinity of MW-8 is discharging to the river. There also is no clear evidence in general, that groundwater discharge from the Site is impacting the river.

Response: See our response to Comment 1B(s).

11B(s). Page 17, fourth paragraph - There is no justification for the conclusion that domestic animals which drink water from the private well north of the Site may "accumulate contaminants" or suffer adverse health effects. As discussed on page 11 of the assessment, MDPH sampled the well in 1988 and found no evidence of organic contamination, and no inorganics present at concentrations indicative of concern to human health. Since the values considered for the assessment of risk to human health are based primarily on animal studies, it is unlikely that domestic animals that drink occasionally from such a well would be adversely affected.

Response: MDCH stands by its analysis and conclusion.

12B(s). Page 19, first paragraph - It is inappropriate to use results from a soil gas survey in a quantitative fashion. A soil gas survey provides information on the spatial orientation of relative amounts of constituents on a given day, but cannot be used in an absolute quantitative sense to determine exceedances of values for the protection of public health.

Response: MDCH interpreted the soil gas results as indicating the possibility of health hazard, and requested further investigation to more fully identify the issue.

13B(s). Page 21, third paragraph, first few sentences - This discussion is confusing. How can one exceed an MRL for non-cancer adverse health effects (7E-05 mg/kg/day for PCBs) but not exceed levels at which adverse health effects are evidenced in laboratory animals? The MRL is based on the human dose extrapolated from data on lab animals.

Response: ATSDR Minimal Risk Levels (MRLs), U.S. EPA Reference Doses (RfDs), and U.S. EPA Reference Concentrations (RfCs) are extrapolated from either human epidemiological or animal laboratory data using safety factors so that the MRLs, RfDs and RfCs are always less than the lowest doses at which adverse health effects have been observed (LOAELs), sometimes by several orders of magnitude. This is a conservative protocol which permits some confidence that exposure to a chemical at levels below the MRL, RfD, or RfC is not likely to result in adverse health effects.

14B(s). Page 22, fourth paragraph - This paragraph is misleading to the general public. As discussed previously, consideration of pica behavior is entirely unreasonable given the likely age of the children who might trespass on the Site. Furthermore, as discussed previously, pica ingestion has not been well quantified, and attempts to quantify pica exposure are highly uncertain.

Response: The paragraph mentions the possibility that children subject to pica behavior might ingest enough of some contaminants from the soil on the site to exceed MRLs, but does mention that children of that age are not likely to be on the site. MDCH and ATSDR considers the pica child as an appropriate conservative scenario for exposure to soil.

15B(s). Page 25, Discussion of Air Pathways - This entire discussion should be eliminated since the results from the various sampling programs appear to be suspect. As discussed on page 10, the contaminants of concern in air are quite likely to have come from off-site sources. This pathway should be re-evaluated in the future under a properly designed and implemented air monitoring program.

Response: We agree that a properly designed air monitoring program will provide an improved basis for the evaluation of the air exposure pathway. The source of the contaminants of concern in the air should be identified so appropriate action can be taken.

16B(s). Page 27, PCBs in Fish - See Comment 2B(s).

Response: See our response to Comment 2B(s).

17B(s). Page 29, Conclusion 1 - The conclusion that the Bay City Middleground Landfill site poses a public health hazard conflicts with the discussions developed within the body of the document. The constituents of interest detected in surface soils, groundwater, and river sediments are low, and in some cases, near background conditions. The constituents of interest which could pose a potential public health hazard are associated with a relatively small area of the Site in the vicinity of MW-8. At this time, there is no conclusive evidence that materials from the MW-8 area have the ability to migrate and come into contact with any potential receptors. While the Site presently has access restriction on three sides, the possibility of trespassing with be greatly reduced upon the installation of a fence along the west branch of the Saginaw River during the summer of 1996. Previous trespasses were probably limited in duration and primarily occurred during winter months when contact with any potential constituents would be extremely limited due to snow cover.

Response: See our responses above to Comment 2B(s).

18B(s). Page 29, Conclusion 2 - It is inaccurate to state that residences close to the Site are not adequately protected from fugitive dust. The Site is presently capped with 2 feet of material, making exposure to fugitive dust extremely unlikely. Previous air monitoring efforts were limited in scope and, as a result, it is difficult to assess whether concentrations of constituents could impact human health in the long term based on these studies.

Response: MDEQ personnel report that not all of the original trenched landfill was covered. Several contaminants of concern were found at concentrations potentially of human health concern in samples of surface soil collected since the landfill cover was installed.

19B(s). Page 29, Conclusion 3 - There has been no valid hydrogeologic study analysis which finds that ground water directly discharges to the Saginaw River. While this conclusion states that ground water "probably" discharges to the river, Conclusion 5 implies that ground water does discharge to the Saginaw River.

Response: See our response to Comment 1B(s).

20B(s). Page 29, Conclusion 4 - The statement that leachate is released to the ditches tells the reader nothing of potential risks associated with the leachate discharge. As discussed on page 27 of the assessment: 1) the only constituent of interest detected in the water from on-site ditches was manganese, and children are unlikely to ingest enough water from the ditch to exceed an intake associated with an adverse health outcome; and 2) the amount of leachate a person would have to drink to incur adverse health effects from the constituents of interest detected (benzene, 1,4-dichlorobenzene, chromium, and nickel) would be 10 percent or more of that person's daily water ingestion rate. This is unlikely.

Response: See our response to Comment 2B(s).

21B(s). Page 29, Conclusion 5 - There is no conclusive evidence that fish in the river have been contaminated with PCBs from the Site.

Response: See our response to Comment 9A.

22B(s). Page 30, Recommendations - The recommendations are not supported by the report as a whole, and in some cases, undermine definitive conclusions drawn in previous sections of the health assessment. For example, the health assessment states in numerous places that groundwater is discharging to the Saginaw River, and Recommendation #5 states that a remediation to eliminate ground-water discharge to the river be implemented. However, Recommendation #3 suggests that a study be conducted to determine whether the shallow aquifer is intercepted by the Saginaw River.

Response: The shallow aquifer may partially discharge to the River and also partially flow under it to the far bank.

23B(s). Page 30, Recommendation 1 - The Site is currently fenced along three sides with the fourth side to be fenced during the summer of 1996. Access to the unfenced side is currently restricted by the west branch of the Saginaw River which only allows access by boaters or during winter conditions when the river might be frozen.

Response: Thank you again for the information about the planned additional fencing at the site. Please see our response to Comment 2B(s) concerning the adequacy of the current fencing.

24B(s). Page 30, Recommendation 2 - It is premature at this time to discuss design components associated with remediation until the completion of the Remedial Investigation/Feasibility Study process.

Response: The precautions recommended here are required in the remediation of all hazardous waste sites. MDCH merely wishes to reinforce that requirement.

25B(s). Page 30, Recommendation 3 - The draft Work Plan submitted to MDEQ on March 18, 1996, does identify a focused investigatory effort of the shallow aquifer in the vicinity of MW-8.

Response: Thank you for the information. The information has been added to the recommendation.

26B(s). Page 30, Recommendation 4 - See Recommendation 2 comment.

Response: The recommendation is meant for consideration during the design of the ultimate remediation of the site.

27B(s). Page 30, Recommendation 5 - See Recommendation 2 comment.

Response: The recommendation is meant for consideration during the design of the ultimate remediation of the site.

FOOTNOTES

1. Reference 3, quote from p. 2-6. There is no further description of the "other uses" in the reviewed literature.

2. On April 1, 1996, the Michigan Department of Public Health (MDPH) Division of Health Risk Assessment (DHRA) was absorbed into the newly-formed Michigan Department of Community Health (MDCH). The site history and background section of this document uses the departmental identifiers in effect at the time of the events.

3. Effective October 1, 1995, the environmental regulation and remediation functions of the Michigan Department of Natural Resources (MDNR) were transferred to the newly-formed Michigan Department of Environmental Quality (MDEQ).

4. Child weight 10 kg; daily water consumption 1 liter; soil ingestion (pica behavior) 5 grams per day. Pica behavior is an abnormal consumption of non-food materials, such as soil, most often seen in children under 5 years of age.

5. Adult Weight 70 kg, Drinking water consumption 2 liters per day, incidental soil ingestion 100 mg per day.

6. See Note 4 on page 8.

7. On April 1, 1996, the Water Supply Division of the Michigan Department of Public Health (MDPH) was transferred to the Michigan Department of Environmental Quality (MDEQ) Division of Drinking Water and Radiological Protection. The organizational identifies used in this document are those in effect when the actions described occurred.

8. The U.S. EPA clean-up guideline for PCBs in residential soil is 1 ppm.

9. The U.S. EPA has issued separate Reference Doses for manganese for ingestion in food and ingestion in water. No adverse health effects from ingestion of manganese in food have been documented well enough to determine a LOAEL. However, epidemiological studies have shown an association between neurological disorders and exposure to manganese through the drinking water (34, 35).

10. See note 9, page 23.

11. See note 9, page 23. A child might exceed the RfD if 10 per cent of his drinking water came from the ditch. An adult would have to take 40 per cent of his drinking water from the ditch to exceed the RfD. Neither of these is considered likely.

12. Table 17 in this document includes only the fish collected in the vicinity of the BCM site. The MDCH based the system-wide advisory on the total data base of fish collected on the Saginaw and Tittabawassee (tributary to the Saginaw) Rivers. The chlordane concentration in one carp or 10 collected from the Saginaw River near the BCM site in 1992 did exceed the U.S. FDA Action Level and MDCH Level of Concern of 0.3 ppm. MDCH issues advisories based on contamination with organic chemicals when 11 per cent or more of the sampled fish exceed the Level of Concern, therefore MDCH does not cite chlordane as a contributing contaminant to the Saginaw River advisory.

13. The U.S. EPA clean-up guideline for PCBs in residential soil is 1 ppm.

14. The Bay City municipal water system is sampled quarterly for a partial chemical analysis including nitrates and trihalomethanes, annually for volatile organic chemicals, limited metals, and cyanide, and twice every three years for semi-volatile organic chemicals.

15. During the Phase III RI, Bay City's contractors reevaluated the data from earlier investigations and determined that the chemical identified as benzidine in the Phase II investigation was probably dibenzothiophene (8).

16. During the Phase III RI, Bay City's contractors reevaluated the data from earlier investigations and determined that the chemical identified as benzidine in the Phase II investigation was probably dibenzothiophene (8).

17. International range of legal limits in fish (23). No MDCH or U.S. FDA Level of Concern.

18. U.S. FDA Action Level = 1.0 ppm

19. U.S. FDA Action Level

20. Total DDT and metabolites

21. Based on age-specific incidence rates per 100,000 population in specific group. Computed by the direct method using as the standard population the age distribution of the entire United States as enumerated in 1970.

22. On April 1, 1996, the Michigan Department of Public Health (MDPH) Division of Health Risk Assessment (DHRA) was absorbed into the newly-formed Michigan Department of Community Health (MDCH). The site history and background section of this document uses the departmental identifiers in effect at the time of the events.

23. Michigan has not yet adopted the proposed protocol, though other states have.


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