AZLE — A plume of trichloroethylene (TCE) an estimated half-mile wide and one mile long remains embedded in soil and groundwater beneath residential portions of Pelican Bay, Azle and Tarrant County.
The U.S. Environmental Protection Agency (EPA) concluded in April — more than four years after the contamination was first acknowledged — that an unknown quantity of TCE was dumped at an illegal site near present day Mountain View Trail, a residential street in Azle.
“It appears to be a relatively old release,” said Vince Malott, the EPA project manager assigned to the Sandy Beach Road Groundwater Plume. “You’re looking at something that’s probably 50 years old. The dump site looks like it was active from the late ’50s all the way up to the 1970s.”
Malott’s estimation delivers a disturbing message to the area’s current and former residents because, according to an EPA site narrative, “The contaminated aquifer and drinking well water have been the only source of water for these residents, who have been drinking the water as well as using it for other consumptive purposes for an indeterminate period of time.”
TCE is a powerful chemical solvent commonly used to remove grease from machinery. The federal government has acknowledged TCE is “probably carcinogenic,” and numerous studies exist linking TCE exposure with neurological, immune system and reproductive defects.
Despite the passage of decades, illegally dumped TCE continues to threaten human health at EPA and Superfund sites around the country because the solvent does not readily dissolve in soil or groundwater.
Scientists think the plume at Pelican Bay migrated southeast from the Mountain View Trail dump site, affecting private wells first before moving on to contaminate two of Pelican Bay’s public water wells.
In addition to contaminated groundwater, the results of a soil gas survey finished last year suggest there is currently a potential for vapor intrusion at residences immediately east of the suspected dump site.
A 2006 study on TCE conducted by the National Research Council concluded, “Indoor air can become contaminated because of volatilization from contaminated water supplies,” and, “Vapor intrusion through walls and floors can be a source of indoor exposure in buildings near contaminated groundwater.”
Most of Pelican Bay’s 1,750 population reside in mobile homes along the western shore of Eagle Mountain Lake. Pelican Bay is separated from the City of Azle by a narrow strip of unincorporated area.
In order to produce a plume as large as the one beneath Azle and Pelican Bay, Malott believes “quite a bit” of TCE must have been dumped.
“The plume itself is so dispersed ... I don’t know how much has actually been pumped out from wells because, certainly, wells have been operating all this time,” he said.
Public water problems
According to state and federal documentation, the Texas Commission on Environmental Quality (TCEQ) first notified the EPA of the contamination at Pelican Bay in March 2004, two months after a pair of public water supply wells were shut down for the second time.
Wells 12 and 13 in the Pelican Bay Public Water Supply were drilled in 1994, when the water company was owned by an individual named Gene Thompson. One year after the wells were completed, the state drinking water authority that preceded TCEQ directed the water company to plug the wells because they were “not developed according to public drinking water standards.”
Despite evidence of TCE, wells 12 and 13 were approved for use again in 2000. The wells remained connected to the public water system until January 2004.
A public health assessment found five water samples from wells 12 and 13 taken between 1994 and 2004 contained TCE concentrations above the minimum accepted levels.
One sample detected TCE levels more than eight times greater than the minimum health-based level.
About 369 of the public system’s 1,475 total users would likely have been consuming contaminated water while wells 12 and 13 were connected, according to a TCEQ hazard assessment formula.
Wells 12 and 13 are currently inactive and the Pelican Bay system is continuing to operate, relying primarily on wells completed in the deeper Twin Mountain Aquifer. So far, contamination has only been detected in wells fed by the Paluxy Aquifer, about 50 feet below the surface.
A public well supplying water for the nearby Timberlake Girl Scout Camp also draws from the deeper Twin Mountain aquifer, according to Camp Director George Hoyle.
Hoyle, 55, said a shallow well supplied the camp until it was replaced during the early ’70s.
Private wells worse
The highest TCE concentrations were detected in private, residential wells.
The EPA reports TCE levels in 10 private wells range from zero to 644 parts per billion (ppb), a level approximately 128 times greater than the minimum accepted threshold.
Tests also concluded some private wells were contaminated with unsafe levels of DCE, a harmful chemical commonly used during the manufacturing phase of certain plastic food wrappers. The highest level of DCE detected — 531 ppb — is more than seven times higher than the minimum health-based standard.
In August 2004, five months after the EPA first acknowledged the contamination, the agency met with local residents to discuss the situation at a nearby school. Based on several estimates, between 50 and 75 people probably attended the meeting.
The next day, the EPA started supplying 10 private residences with bottled water. In addition, contractors were hired to install filtration systems on the 10 corresponding private wells, temporarily decreasing the threat level.
Because vapor associated with TCE-contaminated groundwater is also an exposure pathway, officials urged residents to ventilate their homes during any use of heated water, such as when washing dishes or showering.
Documents suggest the EPA stopped issuing bottled water seven months later, in February 2005, after tests concluded the filtration systems were effectively removing TCE. Officials also started working on a plan to connect the 10 affected residences with a treated surface water supply from the City of Azle.
In April 2005, the Pelican Bay Groundwater Plume was proposed for placement on the National Priorities List (NPL), a collection of the country’s most pressing environmental threats. At the City of Pelican Bay’s request, the site name was officially changed to “Sandy Beach Road Groundwater Plume.”
The site was added to the NPL in September 2005, marking its status as a Superfund site. Since Superfund was established in 1980, only about 1,600 sites nationwide have been involved with the program.
Internet searches failed to turn up any evidence of media coverage related to the contamination or to the site’s Superfund status.
At Camp Timberlake, Hoyle claims the drinking water is clean in part because camp directors receive public water system training from the state. He is concerned for neighbors who get their drinking water from private wells.
“I am [concerned] because I know what bad water will do to their health,” Hoyle said. “Education is the key to them knowing, and some may rebel or reject it, but you still have to put forth the effort to educate them. Historically, high chemical content in drinking water causes deformities and stuff in young people, so I’m really glad [the EPA] is here.”
Rachel Cook, a cashier working at the Lucky Lady convenience store in April, said she was unaware of the TCE threat despite having lived very near the plume’s center for the last four years. The well serving the home she currently lives in — next door to the Lucky Lady — is not currently equipped with a filtration system.
Cook, 22, said her landlord, who lives on Liberty School Road, told her she didn’t need one.
“I was just told that it’s kind of iffy if you’re on well water,” she said. “I need to know if it needs a filter, [my landlord] said he didn’t think so. He said his didn’t need one.”
If properly maintained, officials say the filtration systems effectively prevent human exposure to TCE. But the filters can be easily disconnected.
Some residents unhappy with their well’s diminished performance claim the state provided smaller-capacity filters to save money.
Marcia Franklin, a retired senior citizen who lives on four acres a short distance from the projected dump site, complained the filters “virtually shut down” her well.
“In order to use the water well, the filtration system has to be by-passed so that adequate pressure is available for any kind of use,” she wrote in a June 2005 letter to the EPA.
Jeanie Sharp, one of Franklin’s neighbors, noted similar problems.
“When we want to run the well, we have to do so by using a by-pass on the filtration system,” she wrote. “Otherwise, there is no pressure or volume at all. The man that installed the system said that there is a larger system available, but the state ordered this smaller unit.”
Another nearby resident said he recently disconnected his filtration system when part of his well apparatus toppled over.
The EPA eventually linked Franklin, Sharp and five other Azle residences with the city’s drinking water system. But the remaining three filtration systems — reportedly serving homes along Liberty School Road — straddle Pelican Bay’s city limits. As a result, surface water connections are still thought to be pending amendments to that city’s water supply infrastructure.
The U.S. Health Department has said the filters will be removed as soon as residents are connected to a clean public water supply, or if a connection is declined.
Who is responsible?
Historically, a single Superfund site can take years and hundreds of millions of dollars to clean up.
Potentially responsible parties are sought out at all Superfund sites because such parties often agree to initiate or pay for 70 percent of cleanups started each year, according to the EPA.
Shortly after Sandy Beach Road was added to the Superfund list, scientists started looking for the “smoking gun” — a clue that would reveal who was responsible for dumping the TCE.
“Specifically, what I was looking for were drums or some kind of hard target — something that we could go in there and excavate,” Malott said. “Sometimes drums still have labels on there, and then you can find out who was the source of this.”
Even though the EPA spent more than 15 years remediating another TCE plume about 10 miles away at U.S. Air Force Plant No. 4, Malott is hesitant to link the Sandy Beach Road site with past military industrial operations on the south shore of Lake Worth.
“It’s easy to ‘dog pile’ on them, but in true fairness, there are other potential sources in businesses that could have used the chlorinated solvents,” he said.
The next step
So far, none of the wells completed in the deeper Twin Mountain aquifer show signs of TCE contamination, but Malott said investigators will check for contamination at different intervals in both aquifers.
“The big thing we would be concerned about is some well that goes through both those intervals and is not grouted up properly between the casing and the formation,” he said. “That would give us a vertical pathway.”
According to Malott, it’s too early to assess whether or not the plume has impacted Eagle Mountain Lake. Given the volume of water in the lake, he said it would be difficult to tell.
“It’s unlikely that you would even see [TCE] unless you did sampling right there where the groundwater is discharging into the surface water, but that would be something for down the road, as far as assessing the ecological impact to Eagle Mountain Lake,” he said.
Members of the EPA clean-up crew assigned to Sandy Beach are considering a variety of costly remediation mechanisms. A groundwater extraction plant could be constructed, chemical oxidizers or bacteria could be used and the dirt itself could be replaced, to name a few.
Malott is hopeful investigative field work, which is scheduled to resume in May, will be complete by 2009. The next stage is a feasibility study designed to identify the most effective remediation technology, followed by the actual remediation work, which could take years.
“It’s a really big plume at Sandy Beach,” Malott said.