PUBLIC HEALTH ASSESSMENT
LOWER SALFORD TOWNSHIP, MONTGOMERY COUNTY PENNSYLVANIA
The Salford Quarry no longer poses a public health threat to residents near the site. Boron is the only groundwater contaminant occurring at levels of public health concern. A public water line was constructed in 1993 and, within the past 4 years, has been expanded to serve all homes previously served by private wells that contained boron at levels of health concern. Some residents whose well water contained boron at concentrations below levels of health concern elected not to tap onto the water main.
For about 25 years before 1993, local residents were exposed to boron through well water at concentrations up to 25 parts per million. This level of oral exposure to people drinking the water posed a past public health hazard.
Historical sampling of an off-site spring identified elevated levels of boron, but we have no evidence that anyone consumed the water.
Depending upon results from future sampling, an off-site spring near the site may need to be
restricted from public access.
Salford Quarry is in Lower Salford Township in Montgomery County, Pennsylvania, approximately 30 miles north-northwest of downtown Philadelphia. The site is east of and directly adjacent to Quarry Road (Figures 1,2, and 3). The quarry is an excavation into bedrock that has been almost completely backfilled. The west branch of Skippack Creek runs through an area approximately 500 feet west of the quarry on the west side of Quarry Road.
The Quarry is in a semi-rural area approximately 5 miles west-northwest of Lansdale and within 3 miles of the northeast extension of the Pennsylvania Turnpike. Until the mid-1960s, the entire area surrounding the quarry was used for farming. Since the mid-1960s the number of non-farm residences has increased and the land use in the area surrounding the quarry is rural residential and light agricultural (1).
In the early 1900s, shale from the Brunswick Formation was quarried at this site. The operator used dynamite to blast the rock loose prior to excavation. After the operator had removed a substantial amount of material, water drainage became a problem as water tended to collect in the base of the quarry. Quarrying operations ceased in the 1930s. In the 1950s, the Ludwig & Son waste disposal business of Lansdale, Pennsylvania used the quarry as a site for dumping industrial, commercial and residential wastes. Ludwig & Son disposed between two and five truck loads of waste per day at the quarry for several years. The quarry was also used to dispose of flash cinders from a coal-fired power plant.
In January 1963 American Olean Tile Company, a subsidiary of National Gypsum Company purchased the quarry for use as a landfill for waste from their Lansdale Plant. American Olean disposed of the slurry at the quarry from 1963 through 1980. This tile slurry contained lead, copper, zinc, cadmium, nickel, chromium, vanadium, aluminum sulfate, and other constituents. The tile slurry also contained boron in substantial concentrations (1).
American Olean submitted an application for a solid waste disposal permit to the Pennsylvania Department of Environmental Resources (PADER) on October 27, 1971. A permit was never issued. In December of 1974, at the request of PADER, (now the Pennsylvania Department of Environmental Protection (PADEP)) two monitoring wells were installed at the site. Monthly monitoring began on April 11, 1975.
Before ceasing waste disposal around 1980, American Olean reported to PADER that it had disposed of 284,928 cubic feet of waste (6,476 tons) in the quarry. In 1980, the Commonwealth of Pennsylvania received complaints that tanks were buried on-site. In 1981, the owner discovered two 10,000 gallon tanks containing boron and fuel oil. After the company pumped out the oil, the site officially closed in May 1982 in accordance with a PADER approved plan. This plan called for capping the quarry with compacted soil, and seeding with a grass cover (1).
In 1983, NUS Corporation, acting as an Environmental Protection Agency (EPA) representative, conducted a Site Investigation (SI) as part of the Preliminary Assessment/Site Investigation (PA/SI) process. The results of this site visit were reported to the EPA by NUS on January 3, 1986.
On January 22, 1987 the site was proposed for inclusion on the NPL. American Olean challenged this listing, but a Consent Agreement was entered into on March 22, 1988 between American Olean and EPA Region III. By entering into this agreement American Olean agreed to undertake all actions required for implementation of a Remedial Investigation/Feasibility Study (RI/FS) at the site.
When National Gypsum took title to the site in 1988, American Olean assigned its obligation under the Consent Agreement to National Gypsum. ENVIRON has acted as National Gypsum's contractor in conducting the RI/FS under EPA oversight.
An RI/FS was begun by National Gypsum, the potentially responsible party (PRP), but was interrupted when National Gypsum filed for Chapter 11 reorganization. At that time National Gypsum was voluntarily supplying bottled water to approximately 42 area residences whose wells indicated contamination in an April 1989 sampling round (1 and 5).
National Gypsum challenged the Hazard Ranking Score (HRS) for placing Salford Quarry for the National Priority List (NPL). The case went before a judge, the ruling was found in favor of National Gypsum, and Salford Quarry was deleted from the NPL on June 19, 1992. National Gypsum made a cash settlement to the EPA and the RI/FS was terminated.
EPA rescored the site and reproposed it for inclusion on the NPL on April 1, 1997, and it remains in proposed status.
ATSDR prepared a preliminary health assessment (May 2, 1988) and Addendum (December 13, 1991) for the site. These documents concluded that the site was a potential public health hazard and that EPA's removal action level of 3.2 parts per million (ppm) for boron in drinking water is not protective for infants. It was apparently on the basis of that concentration that EPA provided bottled water. ATSDR recommended monitoring of Skippack and Perkiomen Creeks, downgradient residential wells, and providing potable water to residences where boron exceeds "a level of health concern" (2). An ATSDR site review and update (SRU) (September 1, 1993) concluded that the completion of a public water supply to affected wells removed the health threat. No further follow up was needed. However, expanded well sampling by EPA revealed one home well with a boron concentration of 1.493 ppm (1,493 ppb) further down plume toward the southwest (Figure 3). The public water line was extended and ATSDR published a health consultation (HC) in 1997 on that one well and residence. The HC concluded, after an interview with the family, that no adverse health effects had occurred at that concentration and again recommended no further health actions be taken (3).
On February 12, 1993, J.E. Godfrey and Tom Hartman of the Pennsylvania Department of Health (PADOH) visited the site with representatives of PADEP. While conducting the site visit, staff located monitoring wells in the field. In addition, Mr. Godfrey took strike and dip readings of rock jointing at an outcrop along the west branch of Skippack Creek (Figure 3). There, sedimentary rocks strike about north-45º-east and dip 15 to the northwest. Three prominent joint sets, all with nearly vertical dips, are readily observable (Figure 3). Bedding plane and joint orientations are important because they determine preferential directions of groundwater flow.
On May 19, 1997, Mr. Godfrey and Alice Hoffman (also from PADOH) revisited the site and spoke with area residents about their health concerns, and whether or not they had connected to the public water line.
The site quarry is located in an area where the geologic structure, topography, and pumping wells have combined to form a drumstick-shaped groundwater plume (Figure 3). The boron plume extends down bedrock dip from the quarry perhaps 2,000 feet to private wells along Morris Road (Figure 3). One lobe of the plume appears to extend southward along the topographic lowland of Skippack Creek.
Domestic wells topographically upgradient and downgradient of the quarry along an 8,000 foot northeast-southwest trend (formation strike) are contaminated with boron to concentrations exceeding 20 ppm or 20,000 parts per billion (ppb). Residents have been exposed in the past to boron in groundwater through the use of private wells for as long as 25 years. Now, a public water line serves all homes whose owners have elected to tap on. Without source removal, the quarry contents (now covered) can be expected to continue contaminating groundwater for decades to come (1). The three dimensional extent of the boron plume has yet to be defined by a network of monitoring wells.
ARC/INFO (a geographic information system computer software application) was used to define the population living near the site (Figure 5). The potentially impacted site area was spatially defined as the area within the site boundary plus a one-mile buffer around that boundary. A one-mile buffer is useful for conveying information about the demographic structure of the area adjacent to the site and identifies those who might have a greater potential for exposure. It is important to note, however, that proximity, in itself, is not an adequate indicator of exposure to site-related contaminants. Whenever possible, proximity measures must be supplemented with environmental pathway information to evaluate exposed populations.
We used an "area proportion" technique to calculate the summary population statistics presented. When combining census blocks with buffer distances, the periphery of the obtained boundary commonly intersects a census block. In such cases, applying an area weight factor to the population variables of interest is arguable the best choice for collecting site-specific demographic data. The population in a census block is weighted to reflect the proportion of the block area that is actually in the buffered site area. This method assumes that the population is uniformly distributed throughout the block.
The area shown in Figure 6 is entirely residential. Streams are used recreationally, and some dwellings upgradient of the site may still rely on groundwater for domestic use. All homes downgradient of the site rely on an approved public water supply.
There are multiple sources of health outcome data in Pennsylvania. Health outcome information
include the Pennsylvania Cancer Registry, Vital Statistics Records including live birth, fetal death,
all causes of death, and induced termination of pregnancy. With the exception of mortality data,
the use of the vital statistics for geographic areas smaller than the county may be difficult because
specific rates are only generated for the counties and selected municipalities. In addition, due to
the lack of disease registries of non-cancerous adverse health effects in the State, site-specific morbidity is difficult to assess.
PADOH met with residents during site and community visits. PADOH received one phone call from a citizen about one mile south of the site who expressed concern that boron from the site may have caused his child to become ill. No other citizens expressed health concerns to PADOH or ATSDR.