PUBLIC HEALTH ASSESSMENT
POWELL ROAD LANDFILL
DAYTON, MONTGOMERY COUNTY, OHIO
RESPONSES TO COMMENTS ON THE PUBLIC HEALTH ASSESSMENT,
POWELL ROAD LANDFILL SITE
Responses to comments from Miami Valley Landfill Coalition(comments pages B-7):
General comments. As stated in the public health assessment, PowellRoad Landfill is a public health hazard. It is considered a publichealth hazard because of possible past exposures and the potentialfor human exposure to site-related chemicals. The available datado not indicate that people are currently being exposed; however wehave recommended and expanded soil gas survey and continuedgroundwater monitoring. Public health assessments are not sitespecific health studies. Health assessments are an evaluation ofdata and information on the release of hazardous substances intothe environment in order to asses any current or future impact onpublic health, develop health advisories or other recommendations,and identify studies or actions needed to evaluate and mitigatehuman health effects. If determined by a review of the HealthActivity Recommendation Panel, site specific health studies may beundertaken. ATSDR and ODH determined that Powell Road arearesidents may need information about the nature and possibleconsequences of exposure to contaminants associated with the PowellRoad Landfill. An environmental health education program isrecommended to advise the local medical community and localcitizens about chemical exposure. The following follow-up actionsmay also be considered:
- Inclusion in the TCE subregistry;
- A disease and symptom prevalence study; and
- Development of a voluntary disease and symptom tracking system.
If data become available suggesting that humans are currently beingexposed to levels of hazardous substances that may adversely impacthuman health, ATSDR will reevaluate this site for additionalfollow-up public health actions.
We have addressed some of the community concerns in the CommunityConcerns Evaluation section of this public health assessment.
1) The public comment period was extended to reflect a 30-daycomment period.
2) To our knowledge, there is no "strong evidence" that residentson private wells in the vicinity of PRL are currently ingestingcontaminated drinking water. In the coalition's comments, it isstated that, in 1987 and 1988, Eldorado Plat residents drilled new,deeper wells to replace contaminated shallow wells. This is onlypartially correct. Fifteen wells in Eldorado Plat were tested in1984-85 (WESTON, 1985). Of these, wells 851, 862, 865, and 868,had low levels (<10 ppb) of various Volatile Organic Compounds(VOCs). These chemical compounds included trichloroethene (TCE),1,2-dichloroethene (DCE), toluene, and 1,1-dichloroethane (DCA). All of these wells were screened in the shallow aquifer. Three ofthese wells were replaced with deeper wells in 1987 and 1988.
During the same time period, 12 other private wells in EldoradoPlat, none of which were contaminated, were also either deepened orreplaced with deeper wells. This was the result of falling watertable levels in this portion of the floodplain at this time. TheRemedial Investigation report (RI, 1990, p. 3-14) indicated thatwater levels in wells along Needmore Road dropped about 20 feetbetween 1986 and 1988. The lowering of the water table in the areawas brought about by a combination of drought conditions andincreased pumping by municipal wells in the area. Hydrogeologicstudies presented in the RI indicate that the shallow aquifer thinsto the south under Eldorado Plat, wedged out by an increase in thethickness of the underlying clay-rich till layer (RI, 1990, Figure126.96.36.199). As a result of the falling water tables in the area, thethickness of the saturated portion of the aquifer decreased andwells either went dry or their water yields and water qualitydecreased. This necessitated the drilling of the bulk of the newwells in the area.
Testing of 12 residential wells in Eldorado Plat in 1988 and tworesidential wells in 1991 indicated no contamination of privatewells at this time. We agree that Eldorado Plat is an area atrisk for future groundwater contamination as was indicated by the1991 round of well tests. We specifically noted this in the healthassessment and recommended increased monitoring of these wells aspart of our recommendations for follow-up activities at the site.
3) For most of its history, PRL was a private, basicallyuncontrolled and unrestricted landfill. There is no accurateaccounting of exactly what chemicals were dumped there. No recordswere kept for most of its operational history.
4) It would be preferable to have health data which was basesentirely upon those exposed or potentially exposed. This wouldallow for a true evaluation of the impact of exposure. However,there are two major problems with doing this at Powell RoadLandfill.
The first problem is defining who may have been exposed. There isnot adequate data to identify who may have been exposed or toquantify the amount of that exposure. The population we looked atfor cancer was the only readily available mortality data. Untilrecently, Ohio did not have a cancer registry to track cancerincidence. These data will not be available for review for atleast two years. This is not a case of making a completelydifferent comparison than the one most appropriate; it is a case ofdifference in focus.
The second problem is finding a health outcome which can beadequately measured and is related to the hypothesized exposure. It is important that there be enough cases of the health outcome toprovide for meaningful analysis. Cancer mortality can be measuredand may be caused by some of the chemicals in the landfill,however, if the group defined as exposed is small, it is likelythere will be few or no cases of the cancers caused by thosechemicals.
5) The formulas for calculating the comparison values has beenincluded and are found in Appendix C.
6) We have included recent information published in 1992 in thediscussion of potential health effects.
7) The risk assessments for 1,1,1-trichloroethane,trichloroethene, and xylene are currently under review by aU.S.EPA work group. There are no data to develop the inhalationvalue for trichlorofluoromethane or the oral value forchloroethane (IRIS, January 1993). This is why comparison valueswere not calculated by ODH or ATSDR.
8) If more specific information were available at the time thehealth assessment was released for public comment, it would havebeen included in the public health actions. The public healthaction section in the health assessment serves to identify theactions to be taken and who will undertake these actions. Morespecific information will be released when available.
Responses to Comments from Peter Townsend, hydrologist for MVLC (comments pages B-11):
1) We do not use mass-balance equations and other similarmathematical models to estimate exposure levels associated with thesite. Figure 5 was presented in the health assessment solely toillustrate the hydrogeological conditions under the site, i.e., theextent of the intervening till bed and the known occurrence ofcontaminants in the aquifers beneath the site. The calculatedcontaminant concentrations will be eliminated from Figure 5 in thefinalized version of the health assessment.
2) The probability of new private water wells being drilled in theNeedmore Road-Troy Pike area is minimal given that most residentialareas south of the PRL site (with the exception of Eldorado Plat)are either on OSWC or City of Dayton water. New municipal wellsdrilled in this area are tested for VOCs as a matter of course.Drilling of new municipal wells has to have the approval of theOEPA. Drilling of new private wells is subject to approval by theMontgomery County Department of Health. New private wells arerequired to be sampled only for bacterial contamination. However,the Ohio Revised Code 3708-28-110 states that new private wellswill be located "only where the system and surroundings are suchthat surface and subsurface conditions will not contaminate theprivate water system."
3) One of the reasons for concluding that the site poses a publichealth hazard was the potential for drinking water supplies tobecome contaminated. We did not exclude the area south of the sitestudy area, which includes the Needmore Road area.
VOC contamination in the vicinity of Needmore Road seems to beconcentrated in the deep aquifer in the vicinity of the OhioSuburban Water Company (OSWC) well field, about 3,000 feetsoutheast of the PRL site, and along the northern edge of the Cityof Dayton Miami well field. Currently (1991), the highestconcentrations of VOCs in this contaminant pocket are in monitoringwells MW11B, MW9P, and NPOI-1D (Hydrological Investigation-Addendum, 1992) and OSWC production well #5 (OEPA sampling report,Jan-July, 1992). VOC concentrations appear to lessen sharply awayfrom this area.
The area of maximum contamination corresponds to an area low at thebase of the deep aquifer (RI, 1990, Figure 188.8.131.52). Trichloroethene (TCE) has a specific gravity greater than that ofwater and is a "sinker" in most aquifer systems, eventuallyaccumulating in "pools" along the bottom of the aquifer system(Johnson & Pankow, 1992, Envir. Sci. Tech., 26(5):896-901). VOCsappear to be largely concentrated near the bottom of the deepaquifer, at least in wells NPOI, MW9P, and OSWC well #5. Theadditional contaminants present, 1,2 Dichloroethene (DCE) and vinylchloride, both may form as degradation products due to breakdown ofTCE in groundwater by microbial action.
Sampling of wells in the Needmore Road area in 1984-85 includedcity of Dayton Miami well field production and monitoring wells,Ohio Suburban Water Company production wells, and 70 private andcommercial wells. VOC contamination was detected at highestconcentrations in wells at the Sunny Acres trailer park,residential well 878, the Clark Oil gas station, and in severalwells in the Kitty Hawk Golf course, all along Needmore Road, westof the Old Troy Pike area. A contaminant plume (or plumes)extended from the Sunny Acres trailer park in the north, due southacross the Kitty Hawk Golf course, and into the City of DaytonMiami well field. Contaminated city production wells andmonitoring wells included those in the north-central portions ofthe well field (CH2M Hill, 1986). Monitoring wells and productionwells to the east, adjacent to Old Troy Pike did not indicate anyVOC contamination at this time. The well at the InlandRecreational center, just south of Needmore Road, east of theidentified contaminant plume, and west of the Polish Country Club,had low levels of tetrachloroethylene (1.1 parts per billion) whentested in 1985. However, no TCE, DCE, or vinyl chloride wasdetected in this well.
It is possible that any contamination in the Needmore Road areawill move either into the OSWC well field (pumping 3.8 mgd) or duesouth into the City of Dayton well field (pumping 21-24 mgd) due tothe cones of depression generated by pumping in these well fields. This is borne out by the historical distribution of thesecontaminants (Ch2M Hill, 1986) that indicate, as described above,a discontinuous plume distributed straight south from the SunnyAcres trailer park into the center of the north end of the Daytonwell field and a circular contaminant pocket surrounding the OSWCwell field (Eagon & Associates, FS, 1992). Even though naturalgroundwater flow in the area is S-SE along the trend of the valleytowards the Old Troy Pike area, the pumping in these well fieldswill divert the bulk of the flow into the OSWC well field and S-SWinto the Dayton well field prior to reaching the Old Troy Pikearea.
Well logs obtained from ODNR Division of Water Resources andconversations with Mark Case (Montgomery County Health Dept.)indicate that most residents along Old Troy Pike (roughly 150residences) within a 1.5-mile radius south of the OSWC well fielduse private wells for their water supply. However, with theexception of five homes along Old Needmore Road and the PolishCountry Club well, all other residential wells along Old Troy Pikewithin 1-mile south of the well field are located up out of thefloodplain, upgradient from the identified VOC plume, and areunlikely to be impacted by this contamination. Residences morethan 1-mile south of the well field are downgradient from thiscontaminant source, but are unlikely to be impacted by the NeedmoreRoad contamination due to the effects of increased distance fromthe source (diffusion and dispersal) and the influence of pumpingin Dayton's well field across the river to the west. HistoricalVOC contamination in wells along Old Troy Pike south of CommunityDrive comes from other nearby sources, including the Van DyneCrotty facility, the Valley Crest landfill, and Brandt Petroleum(Mark Case, Montgomery County Health Dept., Dayton Daily News,11/22/92).
Response To OEPA Comments (Memo Amy Gibbons, 11/18/92) (commentspages B-28):
Health assessments are an evaluation of data and information on therelease of hazardous substances into the environment in order toasses any current or future impact on public health, develop healthadvisories or other recommendations, and identify studies oractions needed to evaluate and mitigate human health effects. Thesource of the contamination is not important when considering whatrecommendations are needed, whether the recommendations are forhealth activity follow-up or additional sampling. The source isimportant when considering future contamination or mitigating theexposure. The chemical contamination and the potential for humanexposure is the primary concern.
Comment 11. Page 18, paragraph at the bottom: Without any form ofremediation, travel times to the new well field would be extremelyshort.
Response: The Powell Road Landfill is located less than 2,000 feetdue east of the proposed well field. Modeling studies performedfor the City of Dayton by CH2M Hill (1986),assuming a pumping rateof 21 million gallons per day for the Rip Rap Road well field,indicated that travel times for contaminants in the vicinity of thePRL site to move to wells in the proposed well field would be lessthan 90 days.
REVIEW OF HEALTH ASSESSMENT FOR POWELL ROAD LANDFILL SITE
The following section was not available in electronic format for conversion to HTML at the time of preparation of this document. To obtain a hard copy of the document, please contact:
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation
Attn: Chief, Program Evaluation, Records, and Information Services
1600 Clifton Road NE, Atlanta, Georgia 30333
Calculations for Chemicals that do not cause cancer:
|Comparison Value =||U.S.EPA RfD x Body Weight|
|Exposure Dose =||Medium Concentration x intake rate x exposure factor|
Medium Concentration= the concentration of the chemical in water or soil.
Intake Rate = The amount of water or soil a person would drink or ingest per day.
Exposure Factor = Used to provide an average daily dose whenexposures are intermittent or irregular and less than one year.
Body Weight = The amount a person weights. Generally 70 kilogramsis used for an adult and 10-15 kilograms for a child.
Calculation of risk for those chemicals that may cause cancer:
|Comparison Value =||risk|
Lifetime Excess Cancer Risk =
Annual exposure dose x slope factor x exposure factor in years
Dose is in mg/kg/day
Slope factor = The U.S.EPA cancer slope factor, (mg/kg/day)-1
Exposure factor = Used to adjust the cancer risk if exposures areless than a lifetime (usually defined as 70 years)