Response to Commissioner Scott's Comments
Berks County Commissioner Mark Scott’s provided several comments and questions regarding the Exide investigation and cleanup at the stakeholders meeting on October 10, 2007. Commissioner Scott also spoke at the Exide cleanup public meeting on October 11, 2007. EPA has summarized Commissioner Scott’s comments and provides a response below.
Many of Commissioner Scott’s comments concerned portions of the 1998 Remedial Investigation Report (RIR) provided by Exide to the Pennsylvania Department of Environmental Protection (PADEP). This investigation report was the first attempt at characterizing the historical contamination emitted by the lead smelter.
The United States Environmental Protection Agency (EPA) 2001 Administrative Order on Consent (Order) required Exide to expand the 1998 investigation report with additional characterization. The results of the expanded investigation are available in the following series of documents:
2001 Step1 Environmental Sampling Work Plan
Commissioner Scott expressed concern over the impact of past smelter emissions on groundwater in the area.
The 1998 Remedial Investigation Report referenced groundwater sampling of residential wells in the vicinity of the Exide facility. Twenty-nine residences were sampled on multiple occasions. The process consisted of sampling at several locations (faucet, pressure tank, outdoor spigot) within the household plumbing network under various withdrawal scenarios (e.g., first draw water, extended use). Out of the twenty-nine residences sampled, eleven residences detected lead levels above EPA drinking water standard of 15 parts per billion (ppb).
Lead does not easily leach from soil and impact groundwater. Several conditions (low pH, high temperature and high oxidation-reduction potential) must be present before lead mobility is a problem. Lead much more readily adsorbs to soil particles and stays within the top layer of soil.
Up until the 1950’s, lead pipe was used as water supply line and in plumbing fixtures. Lead was a component in solder used on copper pipes until the1980s. The homes tested were built during this era. In addition, testing of soil during the first phase of the cleanup showed that the lead was not leaching from the soil at appreciable levels.
Given these factors, EPA concluded that the source of the lead found during the Remedial Investigation is the result of the age of the plumbing infrastructure and the homeowners were so informed.
Commissioner Scott had several questions related to the size of the study area.
Figure 1 shows the difference between the 1998 Study Area and the present Study Area.
Figure 1: Delineation of the 1998 Study Area and the Present Study Area
Figure 2: Present Study Area 2007
Commissioner Scott asked several questions regarding the presence of additional metal contaminants, particularly Arsenic and Cadmium in area soils.
In 1997, PADEP directed Exide to sample soils in the vicinity of the Exide facility to determine the extent of the lead contamination. As part of that effort, PADEP required Exide to collect co-located samples to evaluate arsenic and cadmium in soil. The results from the discrete and co-located samples are listed in the table below.
Soil Heavy Metal Results
Note: All values are in mg/kg. Bold values exceed Pennsylvania’s arsenic level of 12 mg/kg for direct soil contact.
Heavy Metal Analysis in Soil
These results show that cadmium levels never exceeded the PA Statewide health level of 47 mg/kg.
There is a moderately strong statistical correlation that relates soil lead level to soil arsenic levels (R=0.75). This means that we can expect the level of lead and arsenic in a given soil sample to be proportional. Thus, EPA is confident that the lead cleanup level of 650 mg/kg will be protective for those few instances where arsenic may also be elevated above the typical EPA cleanup level of 20 mg/kg. In the Exide study area, soils with arsenic levels above 20 mg/kg have already been remediated since these levels were associated with lead levels over 1200 mg/kg.
Out of the 38 samples, one sample detected a 118 mg/kg lead concentration with an arsenic level 22 mg/kg. The sample is located outside the Exide study area. The low soil lead value suggests that the arsenic is unlikely to be from smelter emission and more likely to be from other sources such as pressure treated lumber, fertilizers, or pesticides.
Additional soil samples collected during the 2007 and 2008 sampling events will also be analyzed for arsenic and cadmium. EPA will evaluate the ratios of arsenic and cadmium to lead in soil and will post the results and its final determination at the conclusion of the sampling events
Commissioner Scott expressed concern that the smelter emission contamination of heavy metals could leach out of the soil matrix and move freely in the environment.
Toxicity Characteristic Leaching Procedure (TCLP) tests were conducted during the initial residential cleanups to determine if lead or other metals could leach from the area soils. All of the testing occurred at properties that exhibited soil lead concentrations greater than 1200 mg/kg and as high as 7500 mg/kg. The results of the TCLP tests characterized the soil as non-hazardous and confirmed that heavy metals do not substantially leach from the soil. Below is the range of results of the TCLP tests for the constituents of concern and the allowable TCLP limits.
Toxicity Characteristic Leaching Procedure Results
(Results from the 2001 and 2002 Interim Measures Remedial Closure Reports)