PUBLIC HEALTH ASSESSMENT
SAUK COUNTY LANDFILL
EXCELSIOR, SAUK COUNTY, WISCONSIN
The federal "Superfund" law requires the U. S. Agency for Toxic Substances and Disease Registry (ATSDR) to conduct a health assessment of all toxic waste sites that the U. S. Environmental Protection Agency (EPA) proposes for inclusion on the list of the nation's most hazardous waste sites. This list is called the National Priorities List. The Division of Health (DOH) within the Wisconsin Department of Health and Social Services works with ATSDR to prepare assessments. The purposes of health assessments are:
1. To evaluate whether contaminants at the site pose a current or future threat to public health;
2. To recommend any steps needed to protect the public from exposure to toxic substances, and
3. To recommend long-term health studies, when appropriate.
For each assessment health professionals look at the contaminants present, including each chemical's toxicity; ability to move through soil, water or air; persistence in the environment; and ability to accumulate in the food chain. They look at ways that people could be exposed to contaminants such as eating, breathing, or touching the chemicals. Investigators check relevant health records when appropriate to see if there may be increases in health effects related to public exposure to contaminants from the site. Finally, an assessment identifies the health hazards that a site may pose and recommends action to protect public health now and in the future.
A preliminary public health assessment was done for this site in 1992. Since that time a remedial investigation has been conducted which provided much additional information about the site. This full public health assessment makes use of information from the remedial investigation as well as information provided by citizens living in the area of the site.
Citizens have expressed concerns about the title of this document. The term "Public Health Assessment" can be taken to mean actual evaluations of the health of individuals living near the site. Because the title has been established for this document by ATSDR for all sites, it can not be changed for this site. However, DOH recognizes the concerns and the need for clarification. In creating this document no evaluation of any person's health has been done at this site. This concern is also discussed in the Community Health Concerns section of this document.
The Sauk County Landfill site is located in the township of Excelsior in northeast Sauk County. The site is a closed landfill that operated from 1973 to 1983. Municipal, commercial and industrial wastes were disposed at the site. Approximately 14 acres in size, the landfill is on a 320-acre parcel of County owned property. The landfill was designed to function as a "natural attenuation" site. This means that the site has no liner, leaving the existing sandy soils and sandstone bedrock beneath the site to filter out any contamination leaching from the site. When the site was abandoned in 1983, a clay cap was constructed.
Land use in the area is primarily rural residential with some agricultural properties. There are several homes west of the site along Evergreen Road, Evergreen Lane, and Hogsback Road. These residences rely on private wells for drinking water.
The site currently poses no apparent public health hazard. There are currently no exposures to contaminants from the site that are expected to result in adverse health effects. Volatile organic compounds (VOC) from the site have been detected in one private well. No adverse health effects are expected from exposures to the VOCs in this well. Groundwater contamination at the site may pose a public health hazard in the future, should it migrate from the site at its highest concentrations. If, in the future, people were to rely upon groundwater with the highest concentrations of the contaminants detected in on-site monitoring wells, they would be at an increased risk of getting cancer. Contaminant concentrations have been decreasing rapidly over time, and drop significantly a short distance from the landfill.
Arsenic, beryllium and organic compounds called "PAHs" were detected at elevated levels in on-site soils. These levels are consistent with levels found in areas with heavy vehicle traffic. Because people do not come in contact with these soils on a daily basis they do not pose a public health hazard.
Relatively high levels of carcinogenic VOCs have been detected in soil gas samples from soil gas probes located next to the landfill. While this cannot be associated with an exposure to those VOC's, a low possibility exists for those compounds to migrate to the ambient air at concentrations that could pose a health hazard. A single ambient air sample taken at the gate to the site did not detect any of these carcinogenic VOCs. This sample is not sufficient for ruling out an ambient air exposure on the landfill itself, though off-site migration is unlikely.
A remedy has been selected for this site that includes improving the existing landfill cover, continued monitoring of the groundwater quality, and installing a landfill gas extraction system. Improving the landfill cover will reduce the amount of water entering the landfill and reduce leachate production. Monitoring of the groundwater quality will determine whether the groundwater quality continues to improve and warn of possible private well contamination in the future. The landfill gas extraction system will capture the VOCs, eliminating the possible ambient air exposure and reducing the ability of VOCs to affect groundwater quality.
The DOH recommends that the Evergreen Property Owners Association be kept up to date with any changes or new site related information.
SITE DESCRIPTION AND HISTORY
The Sauk County Landfill site is located in the township of Excelsior in northeastern Sauk County. The site is a closed landfill that operated from 1973 to 1983(1). Approximately 14 acres in size, the landfill is on a 320-acre parcel of County property. The landfill was designed to function as a "natural attenuation" site. This means that the site has no liner, leaving the existing sandy soils and sandstone bedrock beneath the site to filter out any contamination leaching from the site. Municipal, commercial and industrial wastes were disposed at the site. The area consists of rural residential and agricultural land uses.
Figure 1: Sauk County Landfill,
Sauk County, Wisconsin
Sauk County closed the landfill in 1983, and capped it with two feet of clay on the top and one foot of clay on the sides. The EPA investigated the site in 1984 and 1985, and found a plume of ground-water contamination including VOC's extending west from the landfill. Sauk County has added clay to the areas that had subsided and re-vegetated the repaired sections of the cap. The EPA proposed the site for inclusion on the National Priorities List in June 1988, and added the site to the list in October 1989. Inclusion on this list qualifies a site to be cleaned up under the federal "Superfund" program. Sauk County operates the existing county landfill 500 feet north of the old facility. That site is not part of the Superfund action.
Figure 2: Sauk County Landfill
and immediate vicinity
Two bedrock ridges, one about a half mile north and the other about one quarter mile south, rise about two hundred feet above the site. The landfill lies at the head of a valley that slopes gently to the west toward the Baraboo River about three miles away. The site is underlain with stratified sands that were glacially deposited lake sediments extending to a depth of 45 to 75 feet below the surface. Beneath these soils is Cambrian-age sandstone bedrock. The landfill area serves as a recharge area for groundwater that flows down and westward into the valley toward the Baraboo River. Surface water also drains to the west about one mile where it enters a small creek that flows into the Baraboo River.
The geology of the site consists of 20 to 73 feet of unconsolidated material (primarily fine to medium sands with some silt and course sands) overlying bedrock. The upper bedrock consists of 2 to 35 feet of sandstone. Beneath the sandstone lies a siltstone and shale layer that is 60 feet thick to the south of the site but tapers off to the west. Another sandstone bedrock formation lies beneath the siltstone and shale layer. The two principal aquifers are the unconsolidated aquifer and the lower of the two sandstone units. The siltstone and shale act as a semi-confining layer between the upper weathered sandstone bedrock and the lower sandstone across the majority of the county-owned property. A bedrock ridge north and east of the site forms a regional groundwater divide(2).
Depth to groundwater is dependant upon topography and ranges from 30 to 55 feet in the valley. The groundwater depth beneath the ridges and along the edges of the valley ranges from 60 to 160 feet in the sandstone bedrock(3).
Local groundwater flow was found to have four patterns of movement. The flow direction in the unconsolidated aquifer is to the southwest. Near the base of the unconsolidated layer and within the weathered sandstone the flow is to the west-southwest. These flow directions are a result of the topography of the uppermost bedrock surface. Within the siltstone and shale semi-confining layer groundwater flows to the east. Deeper into the lower sandstone bedrock groundwater flows to the northeast(4).
The remedial investigation was completed in April of 1994 and the data from this investigation is incorporated into this report. Based on the results of the remedial investigation and the comments and concerns expressed by the local residents and DOH, a remedy was selected for the site. The selected remedy for the site has the following components:
* continued monitoring of the groundwater at on-site groundwater monitoring wells and off-site
private wells;
* regrading of the landfill surface to promote drainage off of the landfill cover
* fencing the landfill;
* installing a gas extraction system to efficiently collect and combust landfill gases;
* placing a restriction on the property deed such that the surface of the landfill cap is not
disturbed in the future;
* maintaining the landfill cap to prevent erosion and differential settlement; and
* providing a contingency which requires a composite landfill cover system if groundwater quality preventive action limits are not achieved in the future.
Each of these components has been implemented as of the spring of 1995.
DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE
Approximately 18 houses are located on Evergreen Lane, Evergreen Road, or Hogsback Road near the landfill. The Village of Rock Springs (population of about 450) is 3 miles southwest, and the Village of Reedsburg (population of about 5,000) is 6 miles west. An estimated 900 people live within a 3-mile radius and obtain their drinking water from the sandstone aquifer that underlies the site.
While there are many popular recreational and tourist attractions within 3 to 5 miles of the site, there are few resources that would draw nonresidents to the site. A snowmobile trail passes near the north and east borders of the landfill property, uphill from the site. Hunting may also occur on private lands surrounding the site. Access to the county property near the landfill is limited to landfill workers.
The residents near the site have become quite interested in all aspects of the site. They have formed a group called the Evergreen Property Owners Association which received a technical assistance grant from the EPA to help them stay informed and provide input to site activities. The association has sponsored public meetings that have been attended by representatives of the DNR and DOH. As a result of the formation of this group, DOH has been able to efficiently reach all concerned residents living near the site with important information regarding public health.
SITE VISIT
Representatives of the DOH have made several visits to the site over the past few years. Kim Bro of the Wisconsin Division of Health conducted a site visit on March 23, 1989 with a representative of the Sauk County Solid Waste Office. At that time cap over the old landfill was well vegetated with grasses. A wooded area borders the southern and eastern edge of the site, and open meadows border the northern and western sides. The county representative said that deer frequently graze on the cap.
Variable settling of the cap caused water to collect on the top and to seep into the refuse. Several times since the landfill was closed, the county has had to fill, grade and re-vegetate these areas, most recently in 1988. At the time of the site visit, the cap had again subsided as much as two feet in one area. This subsidence altered surface drainage patterns such that runoff water eroded a gully about six inches deep through the east side of the cap.
The site was not fenced except for a gate across the entrance road. The county representative said vandalism had been a problem. Locks had been broken off several of the covers on groundwater monitoring wells. There were no signs of frequent recreational activity, e.g., off-road vehicle tracks or walking paths. Construction debris were deposited in an area about fifty feet west of the southwestern corner of the old landfill. Runoff from the western side of the site flowed into a gravel borrow pit about 100 feet west of the site. At the time of the site visit, the bottom of the borrow pit was covered with water.
On October 19, 1989 Kim Bro and an Denise Jordan-Izaguirre (ATSDR Region 5) visited the site. Except for the absence of water on site, the conditions were the same as those described above. A representative of the DNR visited the site on January 8, 1992. A change in conditions from the past was that debris near the southwest corner of the landfill was covered with soil. The county reported that there has not been a problem with vandalism since the summer of 1990, when landfill staff and the county sheriff discussed the problem with young people living near the landfill.
Chuck Warzecha, of DOH, visited the site several times between March 1992 and early 1994. In early 1992 an erosion gully was noted on the east side of the landfill cap. The cap continued to be well vegetated. However, at the point of the erosion gully, wastes could be seen through the cap. Snow melt on the landfill was not draining properly and was collecting in depressions on the cap. Though standing water was noted near and adjacent to the landfill, no surface water flow from the site was noted. Snow melt and rain water appeared to infiltrate directly to groundwater through the porous sandy soils.
Currently vandalism no longer appears to be a problem at the site. Discussions with residents living near the site indicate that people occasionally drive all-terrain vehicles and snowmobiles on the property. The site is now fenced and posted to prevent access. The landfill continues to be very well vegetated. The erosion gully was repaired and the cap was regraded in 1993.
HEALTH OUTCOME DATA REVIEW
"Health outcome data" is a phrase referring to records of death and disease. When there is evidence that people near a site have been exposed to contaminants at levels that could lead to an increase in rates of death or disease, a review of health outcome data may be appropriate. A review may also be appropriate if there are reports of unusual clusters of disease near a site.
The following community health concerns have been received about the site. These concerns are addressed later in this report.
Groundwater
Air
Other
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