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The UGI Columbia Gas Plant site in Columbia Borough, Lancaster County, Pennsylvania, was proposed for listing on the Environmental Protection Agency's National Priorities List in June 1993. Coal tar waste and boiler ash from a gas manufacturing plant were disposed both on site and off site. Extensive on-site corrective measures were undertaken in 1987, but an indeterminate amount of coal tar remains on site.

On-site exposures to coal tar wastes occurred in the past but are no longer occurring. Most exposures were occupational through inhalation. Data to substantiate airborne exposures both on site and off site are inadequate to evaluate accurately any adverse health effects that may result from the exposures.

Contamination in on-site groundwater has migrated off site and has been detected in deep groundwater near the Susquehanna River. The selected contaminants of concern for the UGI site are the following: arsenic, benzene, benzo(a)pyrene (B[a]P), ethylbenzene, naphthalene, and toluene. A very low potential for exposure to contaminated off-site groundwater exists. About three residential dwellings in the area use private wells for domestic water. Discharge of contaminated groundwater into the river channel presents a remote possibility that some contaminants could enter one of two nearby public drinking water supply intakes of surface water. Potable water supplies do not show evidence of being impacted by the site contaminants.

An area of coal tar-contaminated sediments in the Susquehanna River was identified, but the exact mechanism of placement is uncertain. It has been attributed to active migration of coal tar through the floodplain stratigraphy between the site and the Susquehanna River, but three unidentified pipes with outfalls near the contaminated sediments have been mentioned as possible conduits of the coal tar. Potential exists for human exposure to the contaminated river sediments. A low potential exists for exposure to fish that may bioconcentrate coal tar wastes. Bioconcentration has not been demonstrated in this case.

There are currently no known exposure pathways associated with this site that would have a significant impact on public health. There are no organized or ad hoc groups in the area seeking relief or redress from health problems perceived to be caused by the site. Inadequacies in the available data used to evaluate both completed and potential exposure pathways have led to the conclusion that the UGI Columbia Gas Plant Site is an indeterminate public health hazard. Recommendations are made to address the inadequacies.

The data and information developed in the UGI Columbia Gas Plant Site Public Health Assessment have been evaluated for appropriate follow-up health actions by the ATSDR Health Activities Recommendation Panel (HARP). HARP determined that people are not being exposed to contaminants from the UGI Columbia Gas Plant site at levels that would be expected to cause illness. Therefore, no follow-up health actions are needed at this time. ATSDR will reevaluate this site for additional follow-up public health actions if new data become available that indicate a need to do so.


A. Site Description and History.

On June 23, 1993, the United States Environmental Protection Agency (USEPA) proposed adding the UGI Columbia Gas Plant Site (UGI site), at South Front and Mill Streets in the Borough of Columbia, Lancaster County, Pennsylvania, to the National Priorities List as a Superfund hazardous waste site. The wastes associated with the UGI site are from the manufacture of "water gas" that occurred there for approximately 100 years between 1851 and into the 1950s (1).

The UGI site occupies a 1.6 acre tract of land in predominantly industrial surroundings about 400 feet northeast of the Susquehanna River's Lake Clarke (Appendix A, Figure 1). It is bordered on the northeast by a railroad retaining wall and Conrail tracks, on the southeast by private residential property, on the southwest by Front Street (Pennsylvania Route 441), and on the northwest by an automobile body repair shop (2).

The chief on-site surface features are man-made. Little significant vegetation is present. The ground is relatively flat with no major drainage swales apparent. Most of the area is covered with clean gravel fill, although there are some areas of concrete and a few buildings that were used until recently for boat display, maintenance, and storage (Appendix A, Figure 2). Although one 1935 drawing of the UGI site shows a 12-inch drainage pipe underlying the property (1), neither an inlet to nor an outlet from this structure could be found during site visits. Access to the site is restricted by chain link fencing, topped with barbed wire. The main gates are locked at all times unless activity related to site clean up is underway.

Directly across Front Street to the south-southwest is the Borough of Columbia Wastewater Treatment Plant and a corridor of Conrail tracks. Shawnee Run, a tributary stream to the Susquehanna River, is about 350 feet northwest of the site. A residential area is 200 feet northeast and across a second set of Conrail tracks. About five residences are approximately 1,200 feet southeast of the UGI site, along Route 441, in an otherwise undeveloped tract of land at the Borough boundary (1).

The UGI site was formerly occupied by the Columbia Gas Company, originally organized in 1851 to supply the Borough of Columbia with manufactured water gas. Ownership passed to the Pennsylvania Power and Light Company (PP&L) in 1935 and then to the Lancaster County Gas Company (later merged into UGI) in 1949 (1). For a time the site was privately owned (6). On January 27, 1994, PP&L repurchased the site (23).

Gas reportedly was generated from wood in the earlier years of operation from 1851 to about 1910, although processes probably varied to a certain extent. In 1910 the plant was completely rebuilt except for two gas holders and one boiler. The city gas holder was 40 feet in diameter and was held in a pit to a depth of 17 feet. A poured concrete bottom was discovered in this holder during test borings of the site. The relief holder was 60 feet in diameter and was held in a pit that was 26 feet deep. No man-made base was observed for this holder during test borings (1).

Other structures at the site were two 5-foot UGI water gas sets, a tar separator, and a double unit purifier (1). The 1935 drawing shows that additional smaller equipment such as oil tanks, a cooler tank, and tar tanks were also present (1). Gas manufacturing ceased about 1960 (4).

The process of manufacturing gas consisted of alternately heating a charge of solid organic fuel such as wood or coal to a high temperature inside a generator vessel and passing steam over the heated fuel. Chemical reactions between the steam and the fuel resulted in the production of combustible water gas that was high in hydrogen and carbon monoxide content. Water gas was useful for industrial purposes. Additional treatment of water gas with any of a variety of gaseous hydrocarbon fuels produced "carburetted water gas" that had a higher heating value and was rendered useful as a domestic fuel (5). From the literature reviewed, it is unclear whether or not the latter process was employed at the UGI site.

Byproducts and wastes were generated during the manufacture of these gases. Coal tar was one byproduct, but it also formed one of the three major waste streams at the site. The other two waste streams were boiler ash and spent purifier chips. For purposes of description, the term "tars" as used in this report refers to dark oily liquids and stained soils which have a distinct odor similar to creosote (1).

All liquid waste streams from the manufacturing process were directed to the tar separator. Tars were pumped to the relief holder pit and stored to allow for separation of the tar/water emulsion. Dewatered tars were then pumped to storage tanks and later sold or used as fuel. Overflows from the tar separator were known to occur and the resultant discharges were directed to an open ditch thence to the Susquehanna River (4). Fishermen reported getting tar on their boats at times when fishing in the river.

Boiler ash was the unburned residue of combustion of carbonaceous fuel such as wood, coal, coke, or oil. Most of the boiler ash was hauled away by a contract hauler, but some was disposed in the area across Front Street from the site (1).

Purifier chips were wood chips coated with iron oxide that were held in gas purifier units through which the manufactured gas was passed before storage in the city gas holder. When the chips became saturated with coal tar and could not be economically regenerated, they were spread around the site as paving and dust control material (1).

The relief holder suffered a structural failure in 1947 and was not used as a gas holder after that point in time, but the pit was still used for separation. Good quality tar was removed for sale and unbreakable tar emulsion was left in or returned to the pit. The pit reportedly was filled with general refuse, construction fill, and dirt after gas manufacturing ceased (1).

Tars that were also reportedly left behind in the relief holder pit were displaced from the pit during a site leveling and grading operation. The displaced tars were pushed into a former pedestrian tunnel under the Conrail tracks to the northeast and a small dike, damming up the tars in the tunnel, was built across the entrance (1). The tunnel was accessible to employees at that time and is still accessible from the UGI site but was sealed off at its northeast entry under the tracks during an earlier railroad expansion project.

Extensive remedial action took place at the site in 1987. This consisted of recovery of the pedestrian tunnel and capping of the city gas and relief holders. The recovery of the pedestrian tunnel involved removing the coal tar and visibly contaminated soil, steam cleaning the inside of the tunnel walls, and constructing an eight-inch cement floor. Concrete slabs were poured over both the city gas and relief holders, allowing an undetermined amount of coal tar to remain on site (4).

As part of past studies of the UGI site a number of test pits and borings were excavated on site and off site, and a number of monitoring wells were installed. Samples of soil, river sediment, surface water, and groundwater from areas on site and off site were obtained and chemically analyzed. The results of chemical analyses will be discussed in the Environmental and Other Hazards section.

B. Site Visit

On Wednesday, October 13, 1993, J. E. Godfrey, William G. Schmeer, and Mark A. Lavin, Health Assessors for the Pennsylvania Department of Health (PADOH), conducted a site visit at the UGI site. A second site visit was conducted two weeks later on October 27 by Mr. Lavin, Gail Godfrey from the Agency for Toxic Substances and Disease Registry (ATSDR), and by representatives of the Pennsylvania Department of Environmental Resources (PADER) and Maryland's Department of the Environment. This section discusses relevant observations made by these two teams during the site visits.

At the time of the visits, the site was in use as a boat dealership. We entered the site on Front Street through the main gate, which was open during normal business hours and closed and locked at other times. We found the boat dealership buildings to our left as we entered and to our right we found open-air boat storage. Most of the area was covered with either clean fill, concrete, or the buildings; hence, little vegetation was present on site. In the off-season, boats, trailers, and boating equipment were crowded into the 1.6 acres encompassing the site. Access to the site was restricted by chain link fencing topped with barbed wire. Two watch dogs were kept on site, and the area was lit during hours of darkness.

The northeastern property line abuts a railroad retaining wall that supports Conrail tracks 20 feet above the UGI site elevation. A tunnel, formerly used for pedestrian traffic, passes through the wall and under the tracks. The tunnel is sealed at the northeastern end and was used as a parts storage area. We noticed no odors on site, but some old tar stains were visible on the retaining wall outside the mouth of the tunnel.

The only remaining visible evidence of the gas holders' existence are two rectangular concrete pads at ground level serving as caps for the holder pits. The smaller pad, measuring 40 feet by 45 feet, is situated to the rear of the main building. A demonstration well with a locked cover is near the center of the pad. This pad was constructed during the remedial action of 1987 (4). The larger pad, about 30 feet southeast of the smaller pad and measuring 60 feet by 65 feet, has a similar demonstration well centered in it. This pad was constructed during the same remedial action in 1987 (4). Both pads had freshly patched drill holes in them suggesting that recent sampling of the contents of the pits below had occurred, and, in fact, sampling was done on the day before the first site visit (7).

Two monitoring wells are within the fenced area on site, monitoring wells 3S (MW3S) and 3D (MW3D). Both wells have locked covers on them, and they are between the relief holder pit and Front Street. One is considered a shallow well, the other deep.

We found no large stormwater drainage swales or storm sewer inlets on site. Rainwater that falls on the property appears either to soak into the ground on site or run off as sheet runoff in a poorly defined drainage pattern.

After we inspected on-site areas, we turned our attention to off-site features as we traced the pathway that contaminated groundwater is taking. We inspected such areas as nearby land surfaces and stream banks for signs of contamination that could result in exposure through soils, surface water, or air. We checked areas where off-site disposal of boiler ash was reported to have occurred and where off-site soil borings revealed evidence of tars.

We could see the following off-site features from the main gate: to the southeast, a private residential property; to the southwest, Front Street, a main corridor of Conrail tracks, the Borough of Columbia Wastewater Treatment Plant, and a vacant lot, reportedly the site of a former lace mill; to the northwest, an auto body repair shop; to the northeast, another set of Conrail tracks and rooftops of houses beyond the tracks.

We found monitoring well 4 (MW4) in a grassy area between Front Street and the Conrail tracks just southeast of the UGI site's southeast property line. This well was intact and locked.

We found monitoring well 2 (MW2) in a vacant lot about 40 feet southeast of the point where Shawnee Run emerges from beneath the main corridor of Conrail tracks. During the first site visit this well was intact and locked. However, we discovered during the second site visit that a bulldozing operation of the vacant lot damaged the wellhead by shearing off the casing and exposing the well to the atmosphere. PADER's representative made note of the damage and indicated that action would be taken to correct this problem. The bulldozing also turned over soils on the lot and released some faint odors thought by one person during the site visits to resemble tar odors.

We examined about 1,000 feet of the Susquehanna River bank just west and south of the site. Thousands of small, lively minnows were noted in the water just offshore. A fisherman was angling from the bank and replied, when asked, that he had not seen any tars or oil in the river. No visible tar or odors of tar were detected in the water or along the river banks.

We then found monitoring well 5 (MW5) between the wastewater treatment plant and the river. It was intact and locked.

We then inspected Shawnee Run just upriver from the vacant lot. This stream appeared to be clear and free of tars or oil.

Monitoring wells 6S (MW6S) and 6D (MW6D), which are between the City of Lancaster's Water Supply Pump Station and the river, were northwest of the mouth of Shawnee Run. The former well is a shallow well, and the latter is deep. These are situated on the river bank about 100 feet from the City of Lancaster's water supply intake, which is about 70 feet offshore in the Susquehanna River and about 2,200 feet downstream from the Columbia Water Company's surface water intake.

None of the team members from either site visit detected any visible signs, other than some old tar stains on site. Although one person detected tar-like odors while touring the property across from the UGI site, the odor cannot definitively be associated with the site. Other possible sources, such as creosote-treated railroad ties, were in the area. A demographic survey of the surrounding area conducted during the second site visit is summarized in the next section.

C. Demographics, Land Use, and Natural Resource Use

The UGI site is in a commercial/industrial area of Columbia on the 100 year floodplain of the Susquehanna River (3). According to the 1990 Census, about 10,701 people reside in the Borough of Columbia (10). Of that number, 10,097 are white, 415 are black, and the remainder comprise other categories; 7,649 are 21 years of age or older.

In the northeast quadrant of a one-mile circle centered on the site is a mix of residential, commercial, and industrial properties. Two elementary schools are in this quadrant, each of which is over one-half mile away. Also in this quadrant are many single and multiple family dwellings, a park, and a large foundry.

In the southeast quadrant and within one mile are many residential structures, a small private airfield, an apparently idle factory, an active sawmill, and the confluence of Strickler Run with the Susquehanna River.

In the southwest quadrant within one mile are the Borough of Columbia Wastewater Treatment Plant, the City of Lancaster's water supply intake, the Borough of Columbia's water supply intake, and the confluence of Shawnee Run with the Susquehanna River. The river dominates this quadrant.

In the northwest quadrant within one mile are a large number of residential structures, two active foundries, the central business district of Columbia, a hospital about one mile away, and the Susquehanna River (8).

Most of the residential structures within one mile of the site are frame or brick-and-frame dwellings older than 16 years. Along the Susquehanna River, about 700 feet west of the UGI site, is the first of about 25 cottages, apparently occupied seasonally. Although a public water supply is available to all residences in the borough, not all the cottages are connected to it. A well survey conducted in 1988 identified two cottages that use private well water (19). In 1990, three private wells servicing those cottages were sampled (20). The wells are about 600 feet northwest of MW6D. USEPA initially estimated that 20 residents used these private wells as a source of drinking water (3). However, following the 1990 round of sampling of private wells, USEPA determined that the well water was not used for drinking (20).

The Susquehanna River is the dominant natural feature and resource near the UGI site. It is used by many people for fishing, boating, and swimming. It is a source of water for many uses, including drinking water for the City of Lancaster and the Borough of Columbia, and it receives many wastewater discharges. It flows past Columbia from northwest to southeast to the Chesapeake Bay. It is used for hydroelectric power generation both upstream and downstream from the site.

D. Health Outcome Data

By using state health data bases, special studies, or other relevant health outcome data bases, we may be able to determine whether certain health effects are higher than expected in areas surrounding hazardous waste sites. This section introduces these data bases. An evaluation of the usefulness of these health data as they relate to the UGI site is presented in the Public Health Implications section.

PADOH maintains vital records of live births and resident deaths (including infant and fetal deaths). Resident birth and death information is reasonably accurate to the minor civil division level (township, city, or borough).


PADOH determined community health concerns by asking questions during the site visit, by telephone interviews, by soliciting comments during a public comment period, and by conducting public availability sessions.

USEPA's Remedial Project Manager for the UGI site, PADER's Project Officer for the site, Columbia's Borough Manager, and Columbia Borough's Health Officer all indicated that there are no organized or ad hoc groups in the area seeking relief or redress from health problems perceived to be caused by the site.

On November 2, 1994, PADOH placed a paid legal notice in the Columbia (Pennsylvania) Press that a public comment period ending December 9, 1994, had been opened to receive written comments about the site. No written comments were received during that period.

The only question that was raised by a concerned citizen by telephone was as follows:

    Can exposure to coal tar vapors cause a skin rash?

This question will be addressed in the Community Health Concerns Evaluation section.

PADOH convened two public availability sessions on December 14, 1994, at the Columbia borough offices to provide an opportunity for people to meet PADOH representatives and discuss the public health implications of the UGI site. The sessions were advertised in the Columbia (Pennsylvania) Press on November 30, 1994. Only three people attended these sessions. The people were interested in the health assessment process, especially pertaining to public availability sessions. None had concerns about the site.

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