Thursday, Sept. 28, 2000 | 11 a.m.
A solvent has been found in the ground water underneath a portion of 61 acres of premier downtown land that the city of Las Vegas wants to develop.
Nevada environmental officials have ordered the city to file a cleanup plan by Friday for the contamination, which was found as part of city pumping of standing water at the Bonneville Avenue underpass.
The newly discovered solvent poses no significant health risk, and the cleanup should not slow development of the site, officials said.
The city has pumped ground water from the underpass next to the Clark County Government Center for more than three years to avoid standing water.
The solvent was found in a well that discharges the ground water to storm drains that flow into the Las Vegas Wash, which feeds into Lake Mead, Southern Nevada's major drinking water source.
No one knows the extent of the contamination, but the site, which for 80 years was a railroad fueling station and storage yard for Union Pacific Railroad, has been under a state cleanup order since May 27, 1987. Union Pacific quit fueling operations there in 1991.
The railroad has already spent more than $3 million to clean up the soil, state environmental case officer David Lloyd said.
The state wrote a letter to the city on Aug. 29, noting that the solvent tetrachloroethylene, or PCE, has been monitored in the wells at levels above the national drinking water standard every month except August 1997.
PCE is used in dry cleaning solvents, transformer insulating fluid and as a general industrial solvent. It causes cancer in animals and is suspected of liver and central nervous system damage in humans if inhaled or swallowed.
The state's letter requested a plan by Sept. 15, but that deadline was verbally extended to Friday, state officials said.
The city and Union Pacific Railroad experts have devised a plan to filter the water before it enters the drain, which it intends to file with the state by the deadline, but city spokeswoman Elaine Sanchez said city officials thought they had until next week to reply.
Contrary to earlier environmental reports that predicted contaminants would not reach a well northwest of the underpass for 10 years, tainted water was detected within seven months, the state said.
Not only did the contaminated water exceed the drinking water limit of 5 milligrams per liter, "but the data and chart submitted with the report clearly shows that the concentration has been steadily increasing with time," the state said.
The state has ordered a cleanup plan or proof by the city that the discharge does not violate state water quality standards.
"It does look like there are small amounts of PCE," state enforcement officer Joe Livak said from Carson City.
Livak said the amounts are about double the limit at their peak. Since the ground water is not used for drinking at the site, health risks are minimal at this time.
The extent of the cleanup required will depend on what kind of project is built on the property, Sanchez said. A technical or industrial project would demand less work than housing or apartments, she said.
Lori Wohletz, an environmental expert in the city's Public Works Department, said that although the source of the solvent is unknown, the railroad as former property owner has agreed to clean up contamination until the property is developed.
The Las Vegas City Council delayed plans for developing the site earlier this month until environmental assessments are completed. Las Vegas Business Development Director Lesa Coder said negotiations are under way with developer Lehman Bros., the railroad and the city on how to pay for the cleanup.
Environmental experts are proposing to run the solvent-tainted discharge through carbon filters to remove the PCE before it enters the Bonneville storm drain, Wohletz said, potentially saving millions of dollars by stopping the pollution at the source.
"It does not affect the development of the property," she said. "PCE has been found in shallow ground water all over downtown."
The Southern Nevada Water Authority tests the Las Vegas Wash monthly for 90 organic chemicals, including solvents such as PCE, microbiologist Peggy Roefer said. No PCE has been detected in the wash.
This is not the first time contamination has been found in ground water under the downtown property.
In April 1991 hydrocarbons estimated between 50 and 100 gallons leaked into the ground water from a Calnev fuel station on the western edge of the property. The leak containing benzene, toluene, ethylbenzene and xylenes spilled into the ground water and was treated for the next three years. In January 1997 the state declared the ground water clean.
A recent environmental risk report done for the city by Converse Consultants said further contamination may be discovered in soils and ground water as the site is developed and could become a liability for the city.
There are two sites remaining where diesel fuel floats on top of the ground water from one to three inches deep, Lloyd said. The environmental limit is half an inch.
Converse Consultants estimated a total cost of $750,000 to begin cleaning up the three polluted shallow ground water plumes. On top of that, it will cost $100,000 a year for continued monitoring. Soil cleanup could run from $4.7 million to $7.2 million if further contamination is found.
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