Skip directly to search Skip directly to A to Z list Skip directly to site content




The Southern Maryland Wood Treating (SMWT) site, a National Priorities List site, is a former wood pressure-treating facility in Hollywood, St. Mary's County, Maryland. The facility used creosote and pentachlorophenol as wood preservatives. The soil and groundwater on site are contaminated with pentachlorophenol (PCP) and other phenolic compounds, polynuclear aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). As previously stated in the Agency's public health assessment dated April 10, 1989, until remediation of the site is completed, there is a potential for public health concern because of dermal absorption, ingestion, or inhalation of contaminants from groundwater, surface water, sediments, and soil. Most of the contaminated shallow groundwater is contained on site by a sheet-pile wall. Because groundwater is the primary source of drinking water for the area, the site will pose a public health threat if contamination enters the deep aquifers that supply drinking water to the community. Several tanks on site contain liquid waste. Because those single-wall tanks do not meet current federal and state standards, there is a possibility of further soil and groundwater contamination on site if releases occur.

Residents expressed the concern that their community may have a high rate of cancers. Cancer incidence data are not yet available for St. Mary's and several other counties in Maryland. Incidence is the rate of newly diagnosed cancer cases that occur within a given period of time (usually one year). Because cancer incidence data were not available, ATSDR staff examined cancer death rates. St. Mary's County ranked eleventh out of Maryland's 23 counties, based on an evaluation of the counties' 10-year average cancer death rates (1979-1988). The existing health data provided a general picture of the health of the community, but could not be used to determine if exposure to hazardous substances increased the rate of cancers. Because no other cancer data are currently available, no follow-up evaluation is planned at this time.

Residents are also concerned about the proposed soil-incineration remediation alternative. As a separate action, to evaluate air emissions and determine possible exposure pathways, ATSDR will conduct a detailed review of plans and specifications for the proposed soil incinerator, including trial burn plans and test results, operating conditions, safety, and contingency plans, and air pollution control and continuous monitoring equipment. The ATSDR document, Plan of Action to Evaluate the Proposed Remedial Alternative for the Southern Maryland Wood Treating Site, presents a detailed discussion of the Agency's plans regarding the review of the proposed incinerator.

ATSDR recommends preventing and/or reducing exposures to contaminants associated with this site in the following ways: 1) close the abandoned production well on site to prevent possible contamination of the drinking-water aquifers; 2) evaluate the integrity of the tanks to determine if other storage/disposal options for the liquid wastes are required to prevent additional chemical releases; 3) analyze residential wells near the site for phenolic compounds and PAHs; 4) collect additional hydrogeologic characterization data for drinking water aquifers to detect potential migration of contaminants; and 5) install air monitoring stations at the perimeter of the site during remediation activities.

Based on available information, ATSDR has concluded that the SMWT site poses an indeterminate public health hazard. That category is used to designate sites for which there is incomplete information. The Agency recommends the collection of additional groundwater and air data. ATSDR also recommends that residents avoid exposure to surface water and sediments in Old Tom's Run. There may have been exposures of workers during facility operations through breathing contaminated air and by skin contact. However, there is insufficient information to document exposure duration or exposure levels.

ATSDR's Health Activities Recommendation Panel (HARP) has determined that continued community dialogue is needed. ATSDR conducted public availability (one-on-one) meetings on September 19 and on December 10, 1991, and a public meeting on December 9, 1991, in St. Mary's County. At all three meetings, ATSDR staff discussed community health concerns, including contaminants associated with the SMWT site and EPA's proposed remediation. In addition, the Agency provided information on the steps that are taken by ATSDR to evaluate public health implications of hazardous waste sites and remediation activities. As a followup public health activity, ATSDR will continue its dialogue with the community, working to provide needed health information, which will include information about the proposed incinerator. ATSDR will also seek feedback from residents about concerns and information needs. Based on the information evaluated in the public health assessment, other public health actions are not currently indicated.

While the Public Health Assessment was being finalized for public release, EPA announced that it would undertake a study to identify new cleanup alternatives. The on-site thermal treatment is no longer proposed for implementation. When more information becomes available regarding the other remediation alternatives, ATSDR will evaluate it to determine if further public health actions are indicated for the community near the site.


ATSDR evaluates the public health significance of the Southern Maryland Wood Treating (SMWT) site in this update to the Agency's previous public health assessment, dated April 10, 1989 (Appendix 5). This update is the first part of a response to a petition received from U.S. Senator Barbara A. Mikulski requesting that ATSDR evaluate the possible health effects of the U.S. Environmental Protection Agency's (EPA) proposed soil incineration technology.

The second part of the response will be a detailed review of site-specific incineration information as remediation proceeds. (See ATSDR's Plan of Action to Evaluate the Proposed Remedial Alterative for the Southern Maryland Wood Treating Site for additional details.) This update reevaluates the environmental contamination data as well as any new data collected since the previous public health assessment. ATSDR has identified potential pathways that may be associated with the site and the proposed incineration project. In this public health assessment update, ATSDR recommends actions to prevent or reduce possible adverse health effects. The Agency has also examined available health outcome databases, such as the Maryland Cancer Registry. Those databases provide information on the general health status of the population living near the site. Finally, this update also addresses community health concerns associated with SMWT.

A. Site Description and History

The SMWT site is about 50 miles southeast of Washington, D.C., off Route 235 in Hollywood, St. Mary's County, Maryland. The location of the site is shown in Figure 1 (all figures are in Appendix 1). The site includes approximately 25 acres in the northwestern portion of a 96-acre parcel of property. From 1965 until 1978, SMWT operated a wood pressure-treating facility on the property. The operation used creosote and pentachlorophenol (PCP) as wood preservatives (1).

The wastes generated at the SMWT site included retort and cylinder sludges, process wastewater, and spillage. SMWT used six on-site, unlined lagoons for waste disposal. Waste-disposal practices and spillage resulted in contamination of soils and groundwater with polynuclear aromatic hydrocarbons (PAHs), PCP, and volatile organic compounds (VOCs). Additionally, the sediments and surface-water discharge from an on-site freshwater pond, shown in Figure 2, became contaminated from the wood-treating operations.

In 1982, the Maryland Department of Health and Mental Hygiene began enforcement actions to require cleanup. Liquid wastes from the lagoons were sprayed into nearby on-site wooded areas. The sludges from the lagoons were mixed with wood chips and composted sewage sludge. That material was spread on the southeastern section of the property, a process known as land application and treatment. The goal was to reduce contaminant concentrations through biodegradation. That effort was unsuccessful and resulted in an increased area of contamination (1).

EPA began a removal action in 1985. Straw-filter fences were installed to control the migration of sediments downstream along the western tributary. In January 1986, EPA excavated approximately 1,400 cubic yards of soil and sediment from the freshwater pond. The contaminated material was placed on a synthetic liner and capped with a synthetic cover. EPA completed a Remedial Investigation/Feasibility Study (RI/FS) in May 1988, and in June of the same year issued a Record of Decision (ROD) for the site. The following remediation alternatives were selected: excavation of surface and subsurface soils and sediments from the pond, the process, and the land-treatment areas; on-site incineration of the contaminated materials including excavated/dredged soils, sediments, cement, and tank liquids; pumping and treatment of contaminated groundwater; containment of shallow groundwater contamination to prevent off-site migration; and backfilling, regrading, and revegetating the site as necessary (2).

During 1989 and 1990, under U.S. Army Corps of Engineers' supervision, a containment wall was built around the area having the greatest groundwater contamination. The wall is constructed of steel sheet pilings driven into a clay formation under the shallow aquifer. The wall is intended to prevent groundwater migration and to allow the area to be dewatered before contaminated soils are excavated and incinerated (2). Analysis of groundwater in one of the shallow monitoring wells indicates very low levels of off-site contamination. Those low levels were estimated and could not be accurately determined (1).

B. Site Visits

On September 17, 1991, Joe Carpenter of ATSDR visited the site along with representatives of EPA and Maryland Department of the Environment. The EPA Remedial Project Manager led the tour of the site, noting areas that had been addressed during the previous removal actions. Several buildings and sheds, and numerous storage tanks remain on the property. The locations of those structures and tanks are shown in Figure 3.

The buildings are constructed of cinder blocks and the sheds are made of treated poles with tin roofing and siding. Several of the above-ground storage tanks appeared to be in poor condition. The tanks are made of single-wall steel with an asphalt coating. The bottoms of the tanks contact soil and are partially covered by it. The tanks are not equipped with leak detection or corrosion protection.

The site is surrounded by an eight-foot chain link fence with a locked gate at the entrance. There is a small retail outlet for pretreated lumber and crab traps at the entrance to the property on Route 235.

On December 9-10, 1991, Lorna Bozeman, Joe Carpenter, Cynthia Lewis, Harvey Rogers, and Betty Willis of ATSDR visited the SMWT site area. All gates at the site were locked, so the health assessors viewed the area by walking around the fence line. The fence surrounding the site appeared adequate to prevent trespassing, except for one area where a gap under the fence was noted. A single sign posted at the main entrance warns that the site contains hazardous materials. It appears that a portion of the freshwater pond (see Figure 2) is outside the containment area because standing water was observed on both sides of the piling wall. The water may be groundwater or pond water. Three deer were seen on the site during the tour.

Off site, ATSDR staff saw an oily sheen on the western tributary below the pond. The eastern tributary was not visibly contaminated. Figure 2 shows the location of those tributaries. Outside the fence were observed several unlabeled drums near monitoring wells in the field and in the woods on the western, southern, and southeastern sides of the site. The drums appeared full and in good condition. Areas south and east of the site are wooded; areas north and northeast are covered with briars, brush, and small trees.

On the west side of the site, near the piling wall, a number of shotgun shell casings were found just outside the fence. There was a path along the fence line leading to the western tributary of Old Tom's Run. Five single-family houses, a mobile home, and a house under construction are within one half mile west-northwest of the site. The SMWT production area and piling wall are clearly visible from the residences and from a large open field, which are adjacent to the western side of the site.

ATSDR staff obtained information about the area from several local contacts: St. Mary's County Health Department, Chamber of Commerce, Planning Office, Airport, and from Leonardtown City Hall. Information from those sources is incorporated into the appropriate sections of this public health assessment update.

C. Demographics, Land Use and Natural Resource Use


Demographic information is presented for St. Mary's County as well as for specific areas immediately surrounding the SMWT property. In 1990, the county had a population of nearly 76,000, an increase of 27 % over the 1980 Census population of just under 60,000. Those figures are indicative of rapid population growth, which is likely due to the area being close to Washington, D.C. The population was 84.4 % white, 13.5 % black (including African-American), and 2.1 % other races. Approximately 17 % of the population were under age 10 in 1990, and 9 % were age 65 or older. There were nearly 3 persons per household in 1990. The median value of owner-occupied housing units was $109,100 (3).

The block group in the census tract encompassing the site had a 1990 population of 1,194, of which 51 % were male and 49 % female. More than 93.6 % were white, 4.8 % were black (including African-American), and 1.6 % were of other races. Just over 19 % were under age 10 in 1990; only 4.4 % were age 65 or older. There were 388 households (i.e., occupied housing units) with a relatively high average of 3.08 persons per household. More than 83 % of all housing units were owner occupied, and the median value of owner-occupied homes was more than $110,000. Those figures suggest a nontransient population of middle- to upper-socioeconomic status (3).

The block group immediately across Route 235 northeast of the site had a population of 1,402, of which 50.5 % were male and 49.5 % female. Nearly 95 % were white, 3.6 % black (including African-American), and 1.5 % other races. Slightly more than 1 % were of Hispanic origin. Approximately 16.3 % were under age 10, and 7.6 % were age 65 or older. The 489 households had an average of 2.87 persons per household. More than 81 % of the housing units were owner occupied, and the median value of owner-occupied homes was $106,700 (3).


The SMWT site, now zoned industrial, is bounded on the east and south by a hardwood forest, and on the west by fields. An abandoned railroad line runs along the northern property boundary, an area covered with grasses, briars, and small, thorny locust trees. There are homes within a half mile north and west of the site (see Figure 1). Future residential development of property adjoining the western boundary of the SMWT site has been proposed. During 1990-91, preliminary plans for a 51-lot, single-family subdivision on 200 acres, Newton Manor, were submitted for approval to the St. Mary's Board of County Commissioners. The applications have been repeatedly denied based upon concerns about the ongoing EPA Superfund clean-up project at the adjacent SMWT property. The Newton Manor property owners are pursuing legal channels to appeal the decision (4,5).


The residents of St. Mary's County use groundwater for their drinking water supply. Four groundwater zones are used for domestic water supplies. All four zones are composed of unconsolidated sediments such as clays, silts, sands, and gravels.

The water table aquifer is the shallowest zone, found within a few feet of the surface to the top of a clay layer approximately 30 feet below the surface. Groundwater in this zone feeds local streams, and recharges the underlying zone. There are two active residential wells within 400 yards north and northwest of SMWT that draw from that zone; water yields range from two to 10 gallons per minute (gpm) (1). The direction of groundwater flow in the zone appears in Figure 4. The state of Maryland does not allow construction of new residential wells drawing from that zone. The law specifically requires that public and private wells be installed in "confined aquifers."

The second water-bearing zone begins 50 feet below the land surface and is beneath a layer of clay that is part of the Chesapeake Group. That layer of interbedded sand, silt, and clay units starts about 30 feet below land surface and is approximately 250 feet thick. Four monitoring wells are screened (50-60 feet deep) in the uppermost region of the Chesapeake Group at the SMWT site. Groundwater flow is estimated to be toward the southeast away from SMWT and is shown in Figure 5. In the remainder of this public health assessment, ATSDR refers to that sand-bearing stratum as the Upper Chesapeake aquifer.

The third groundwater zone, the Piney Point-Nanjemoy aquifer, is below the Chesapeake Group. The aquifer ranges in depth from 285 to 325 feet deep and serves as the primary source of drinking water for residents in the vicinity of the SMWT site. The Chesapeake Group serves as the confining layer for the aquifer. The direction of groundwater flow in that aquifer is southeast at SMWT. Yields from wells using the Piney Point-Nanjemoy aquifer are about 100 gpm or less (1).

The fourth zone, known as the Aquia Formation aquifer, is 495 to 600 feet deep. Groundwater flows in a southeasterly direction. Yields from wells screened in the aquifer are approximately 300 gpm. The on-site production well at SMWT is screened in the Aquia aquifer. The production well has not been used in the past few years, and it has a blocked well casing that prevents sampling.

Two tributaries drain surface-water runoff away from the SMWT site. A pond discharge on the southwestern portion of the site is the headwater of Old Tom's Run (see Figure 2). The eastern tributary discharges into Old Tom's Run and ultimately into the Potomac River via Brooks Run and McIntosh Run. The site is near the drainage divide between the Potomac and Patuxent Rivers. Surface water in the immediate vicinity of the site is not used for drinking water or recreation. Fishing is unlikely because creeks and drainages receiving rainwater runoff from the site are considered too small to support edible fish populations. Old Tom's Run flows through woods south of the site. A trail through the meadow along the western boundary of the SMWT property leads back to the creek. It is possible that children who live near the site use the creek as a play area (1).

Local rainfall is approximately 40 inches per year. The average annual snowfall is around 16 inches, with snow cover for approximately 13 days per year. The wind direction is primarily from the northwest and the south (see Figure 6) (1).

Wild game in the area include white-tailed deer, rabbits, and squirrels. A local sporting goods store employee said that hunting of those animals is common in the site vicinity. He also said that doves are the predominant game birds in the area.

D. Health Outcome Data

Three sources of health outcome data were available for review. The 1986 and 1987 state of Maryland Vital Statistics Reports were examined (6,7). Limited data from the Maryland Cancer Registry were provided to ATSDR through the Governor's Council on Cancer Control (8). Mortality data from the Centers for Disease Control's Wideranging ONline Data for Epidemiological Research (WONDER) Database, including national as well as regional statistics, were also reviewed (9).


ATSDR met with citizens of St. Mary's County on September 19, 1991, December 9, 1991, and December 10, 1991, to discuss community health concerns about the SMWT site. Two of the meetings were one-on-one public availability sessions intended to allow individuals to discuss their concerns with ATSDR staff. The third meeting was held as an open forum group meeting.

The residents expressed a general objection to incineration as a remediation technology in their community. Residents asked a number of questions regarding ATSDR's role in the proposed site remediation process. Those questions were addressed during the meetings, but, because they were not specifically health-related or did not involve the proposed incineration process, they are not included in this public health assessment. Community health concerns are summarized below:

1. The major community health concern was about the potential health effects of the incineration process that EPA plans to use to remediate the site. Specifically, how will the stack emissions such as products of incomplete combustion (PICs) and metals affect community health? How will equipment failures, process upsets, and other emergency situations affect remediation air releases?

2. Is the current groundwater monitoring program adequate to detect contamination of drinking water wells in the area? The public is concerned that the production well may allow contamination of the deep aquifers.

3. What is the effect of the site's contaminants on the food chain? Are fish, shellfish, game, and crops in the area currently affected? Will the incinerator emissions affect the food chain?

4. Does the county have a high cancer rate?

5. How will sensitive populations be effected by this site and by future remediation activities?

6. Are the chemicals at SMWT, and the future incinerator-stack emissions cancer promoters or initiators?

7. Will ATSDR do any follow-up health studies of the community to see if the remediation activities affect residents' health?

Those concerns will be addressed in the Community Health Concerns Evaluation section.

Next Section          Table of Contents The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO

A-Z Index

  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #