PUBLIC HEALTH ASSESSMENT
POWELL ROAD LANDFILL
DAYTON, MONTGOMERY COUNTY, OHIO
Figure 2. Gas Vent Vapor
Total VOC Concentrations
Figure 3. Landfill Liquids/Ground Water
Total VOC Concentrations
Figure 4. Volatile Organic Compounds
detected in Groundwater - April, 1989M
Figure 5. Distribution of
TILL LAYER at PRL site
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, Powell Road Landfill is a public health hazard. It is considered a public health hazard because of possible past exposures and the potential for human exposure to site-related chemicals. The available data do not indicate that people are currently being exposed; however we have recommended and expanded soil gas survey and continued groundwater monitoring. Public health assessments are not site specific health studies. Health assessments are an evaluation of data and information on the release of hazardous substances into the environment in order to asses any current or future impact on public health, develop health advisories or other recommendations, and identify studies or actions needed to evaluate and mitigate human health effects. If determined by a review of the Health Activity Recommendation Panel, site specific health studies may be undertaken. ATSDR and ODH determined that Powell Road area residents may need information about the nature and possible consequences of exposure to contaminants associated with the Powell Road Landfill. An environmental health education program is recommended to advise the local medical community and local citizens about chemical exposure. The following follow-up actions may 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 being exposed to levels of hazardous substances that may adversely impact human health, ATSDR will reevaluate this site for additional follow-up public health actions.
We have addressed some of the community concerns in the Community Concerns Evaluation section of this public health assessment.
1) The public comment period was extended to reflect a 30-day comment period.
2) To our knowledge, there is no "strong evidence" that residents on private wells in the vicinity of PRL are currently ingesting contaminated drinking water. In the coalition's comments, it is stated that, in 1987 and 1988, Eldorado Plat residents drilled new, deeper wells to replace contaminated shallow wells. This is only partially correct. Fifteen wells in Eldorado Plat were tested in 1984-85 (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 of these wells were replaced with deeper wells in 1987 and 1988.
During the same time period, 12 other private wells in Eldorado Plat, none of which were contaminated, were also either deepened or replaced with deeper wells. This was the result of falling water table levels in this portion of the floodplain at this time. The Remedial Investigation report (RI, 1990, p. 3-14) indicated that water levels in wells along Needmore Road dropped about 20 feet between 1986 and 1988. The lowering of the water table in the area was brought about by a combination of drought conditions and increased pumping by municipal wells in the area. Hydrogeologic studies presented in the RI indicate that the shallow aquifer thins to the south under Eldorado Plat, wedged out by an increase in the thickness of the underlying clay-rich till layer (RI, 1990, Figure 3.6.1.2). As a result of the falling water tables in the area, the thickness of the saturated portion of the aquifer decreased and wells either went dry or their water yields and water quality decreased. This necessitated the drilling of the bulk of the new wells in the area.
Testing of 12 residential wells in Eldorado Plat in 1988 and two residential wells in 1991 indicated no contamination of private wells at this time. We agree that Eldorado Plat is an area at risk for future groundwater contamination as was indicated by the 1991 round of well tests. We specifically noted this in the health assessment and recommended increased monitoring of these wells as part of our recommendations for follow-up activities at the site.
3) For most of its history, PRL was a private, basically uncontrolled and unrestricted landfill. There is no accurate accounting of exactly what chemicals were dumped there. No records were kept for most of its operational history.
4) It would be preferable to have health data which was bases entirely upon those exposed or potentially exposed. This would allow for a true evaluation of the impact of exposure. However, there are two major problems with doing this at Powell Road Landfill.
The first problem is defining who may have been exposed. There is not adequate data to identify who may have been exposed or to quantify the amount of that exposure. The population we looked at for cancer was the only readily available mortality data. Until recently, Ohio did not have a cancer registry to track cancer incidence. These data will not be available for review for at least two years. This is not a case of making a completely different comparison than the one most appropriate; it is a case of difference in focus.
The second problem is finding a health outcome which can be adequately measured and is related to the hypothesized exposure. It is important that there be enough cases of the health outcome to provide for meaningful analysis. Cancer mortality can be measured and may be caused by some of the chemicals in the landfill, however, if the group defined as exposed is small, it is likely there will be few or no cases of the cancers caused by those chemicals.
5) The formulas for calculating the comparison values has been included and are found in Appendix C.
6) We have included recent information published in 1992 in the discussion of potential health effects.
7) The risk assessments for 1,1,1-trichloroethane, trichloroethene, and xylene are currently under review by a U.S.EPA work group. There are no data to develop the inhalation value for trichlorofluoromethane or the oral value for chloroethane (IRIS, January 1993). This is why comparison values were not calculated by ODH or ATSDR.
8) If more specific information were available at the time the health assessment was released for public comment, it would have been included in the public health actions. The public health action section in the health assessment serves to identify the actions to be taken and who will undertake these actions. More specific 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 similar mathematical models to estimate exposure levels associated with the site. Figure 5 was presented in the health assessment solely to illustrate the hydrogeological conditions under the site, i.e., the extent of the intervening till bed and the known occurrence of contaminants in the aquifers beneath the site. The calculated contaminant concentrations will be eliminated from Figure 5 in the finalized version of the health assessment.
2) The probability of new private water wells being drilled in the Needmore Road-Troy Pike area is minimal given that most residential areas south of the PRL site (with the exception of Eldorado Plat) are either on OSWC or City of Dayton water. New municipal wells drilled in this area are tested for VOCs as a matter of course. Drilling of new municipal wells has to have the approval of the OEPA. Drilling of new private wells is subject to approval by the Montgomery County Department of Health. New private wells are required to be sampled only for bacterial contamination. However, the Ohio Revised Code 3708-28-110 states that new private wells will be located "only where the system and surroundings are such that surface and subsurface conditions will not contaminate the private water system."
3) One of the reasons for concluding that the site poses a public health hazard was the potential for drinking water supplies to become contaminated. We did not exclude the area south of the site study area, which includes the Needmore Road area.
VOC contamination in the vicinity of Needmore Road seems to be concentrated in the deep aquifer in the vicinity of the Ohio Suburban Water Company (OSWC) well field, about 3,000 feet southeast of the PRL site, and along the northern edge of the City of Dayton Miami well field. Currently (1991), the highest concentrations of VOCs in this contaminant pocket are in monitoring wells 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 away from this area.
The area of maximum contamination corresponds to an area low at the base of the deep aquifer (RI, 1990, Figure 3.6.1.1). Trichloroethene (TCE) has a specific gravity greater than that of water and is a "sinker" in most aquifer systems, eventually accumulating in "pools" along the bottom of the aquifer system (Johnson & Pankow, 1992, Envir. Sci. Tech., 26(5):896-901). VOCs appear to be largely concentrated near the bottom of the deep aquifer, at least in wells NPOI, MW9P, and OSWC well #5. The additional contaminants present, 1,2 Dichloroethene (DCE) and vinyl chloride, both may form as degradation products due to breakdown of TCE in groundwater by microbial action.
Sampling of wells in the Needmore Road area in 1984-85 included city of Dayton Miami well field production and monitoring wells, Ohio Suburban Water Company production wells, and 70 private and commercial wells. VOC contamination was detected at highest concentrations in wells at the Sunny Acres trailer park, residential well 878, the Clark Oil gas station, and in several wells in the Kitty Hawk Golf course, all along Needmore Road, west of the Old Troy Pike area. A contaminant plume (or plumes) extended from the Sunny Acres trailer park in the north, due south across the Kitty Hawk Golf course, and into the City of Dayton Miami well field. Contaminated city production wells and monitoring wells included those in the north-central portions of the well field (CH2M Hill, 1986). Monitoring wells and production wells to the east, adjacent to Old Troy Pike did not indicate any VOC contamination at this time. The well at the Inland Recreational center, just south of Needmore Road, east of the identified contaminant plume, and west of the Polish Country Club, had low levels of tetrachloroethylene (1.1 parts per billion) when tested in 1985. However, no TCE, DCE, or vinyl chloride was detected in this well.
It is possible that any contamination in the Needmore Road area will move either into the OSWC well field (pumping 3.8 mgd) or due south into the City of Dayton well field (pumping 21-24 mgd) due to the cones of depression generated by pumping in these well fields. This is borne out by the historical distribution of these contaminants (Ch2M Hill, 1986) that indicate, as described above, a discontinuous plume distributed straight south from the Sunny Acres trailer park into the center of the north end of the Dayton well field and a circular contaminant pocket surrounding the OSWC well field (Eagon & Associates, FS, 1992). Even though natural groundwater flow in the area is S-SE along the trend of the valley towards the Old Troy Pike area, the pumping in these well fields will divert the bulk of the flow into the OSWC well field and S-SW into the Dayton well field prior to reaching the Old Troy Pike area.
Well logs obtained from ODNR Division of Water Resources and conversations with Mark Case (Montgomery County Health Dept.) indicate that most residents along Old Troy Pike (roughly 150 residences) within a 1.5-mile radius south of the OSWC well field use private wells for their water supply. However, with the exception of five homes along Old Needmore Road and the Polish Country Club well, all other residential wells along Old Troy Pike within 1-mile south of the well field are located up out of the floodplain, upgradient from the identified VOC plume, and are unlikely to be impacted by this contamination. Residences more than 1-mile south of the well field are downgradient from this contaminant source, but are unlikely to be impacted by the Needmore Road contamination due to the effects of increased distance from the source (diffusion and dispersal) and the influence of pumping in Dayton's well field across the river to the west. Historical VOC contamination in wells along Old Troy Pike south of Community Drive comes from other nearby sources, including the Van Dyne Crotty 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) (comments pages B-28):
Health assessments are an evaluation of data and information on the release of hazardous substances into the environment in order to asses any current or future impact on public health, develop health advisories or other recommendations, and identify studies or actions needed to evaluate and mitigate human health effects. The source of the contamination is not important when considering what recommendations are needed, whether the recommendations are for health activity follow-up or additional sampling. The source is important when considering future contamination or mitigating the exposure. The chemical contamination and the potential for human exposure is the primary concern.
Comment 11. Page 18, paragraph at the bottom: Without any form of remediation, travel times to the new well field would be extremely short.
Response: The Powell Road Landfill is located less than 2,000 feet
due east of the proposed well field. Modeling studies performed
for the City of Dayton by CH2M Hill (1986),assuming a pumping rate
of 21 million gallons per day for the Rip Rap Road well field,
indicated that travel times for contaminants in the vicinity of the
PRL site to move to wells in the proposed well field would be less
than 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
Branch, E-56
1600 Clifton Road NE, Atlanta, Georgia 30333
Calculations for Chemicals that do not cause cancer:
| Comparison Value = | U.S.EPA RfD x Body Weight Intake |
| Exposure Dose = | Medium Concentration x intake rate x exposure
factor Body Weight |
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 when exposures are intermittent or irregular and less than one year.
Body Weight = The amount a person weights. Generally 70 kilograms
is used for an adult and 10-15 kilograms for a child.
Calculation of risk for those chemicals that may cause cancer:
| Comparison Value = | risk Slope Factor |
x | Body Weight Intake |
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 are less than a lifetime (usually defined as 70 years)
