A century of trains leaves unwanted legacy
BNSF consultants: Diesel plumes are 'weathering' away
By RICHARD HANNERS / Whitefish Pilot
BNSF Railway's recent interest in acquiring properties in Whitefish's Railroad District has a lot of people wondering about the status of spilled fuel forming underground plumes on the railroad's property.
While many questions remain, a significant amount of data is available from BNSF's consultant. The plumes seem to be stable and slowly weathering away, the consultants say — and that could inform what kind of clean-up plan is adopted by the state.
While BNSF began clean-up operations at its Whitefish fueling facility in 1973, government action didn't begin until a citizen complained about an oil sheen in the Whitefish River in 1986.
Remedial investigations
The railroad began a remedial investigation in 1987 at the request of the state, which had recommended no additional action by the U.S. Environmental Protection Agency.
Studies found free product floating on groundwater, and clean-up activities continued through 1989, at which time the Montana Highway Department initiated studies for construction of the Baker Ave. viaduct.
The highway studies revealed underground fuel plumes east and west of the depot caused by passenger-train fueling operations.
BNSF's consultants, Kennedy/Jenks, of Federal Way, Wash., issued its Final Draft Remediation Investigation (RI) report in May 2006. Their supplemental RI report the next year confirmed the Final Draft RI's findings and conclusions.
Denise Martin, the Montana Department of Environmental Quality section manager who is temporarily serving as project manager for the Superfund site, says DEQ "is in the process of reviewing" the Final Draft RI.
"Due to limited staff resources, we do not currently have a project officer assigned to this facility," DEQ director Richard Opper said in an April letter to Whitefish city councilor John Muhlfeld. DEQ is actively recruiting to fill that position, Opper said, and hopes to have it filled soon.
The Final Draft RI identified several "chemicals of interest" that exceeded government screening levels or standards at some locations:
¥ Diesel and Bunker C fuel above groundwater forming several large underground plumes.
¥ Dissolved trichloroethane, a solvent used in equipment repair, west of the Roundhouse Shop.
¥ Polynuclear aromatic hydrocarbons in surface soils on the north side of the tracks, particularly where the former Motor Repair Building once existed next to Edgewood Place.
¥ Antimony, arsenic, cadmium, chromium, lead, nickel and zinc in the surface soil west of the Roundhouse Shop and north of the tracks. Some of these metals are associated with babbit alloy used in journal bearings for railcar wheels.
¥ Volatile petroleum hydrocarbons and extractable petroleum hydrocarbons in subsurface soil down-gradient from two monitoring wells at the southwest corner of the Baker Ave. viaduct.
Besides noting that several contaminants exist at levels below screening levels and standards, Kennedy/Jenks reported that no PCBs had been detected, and chromatograms of free product suggest the presence of diesel fuel and not Bunker C oil.
A history of spills
Great Northern Railway established a railyard facility in Whitefish in 1904 with a roundhouse and repair shops. Coal- and wood-powered locomotives eventually gave way to liquid fuels — Bunker C, a heavy fuel oil, and diesel beginning in the 1940s.
Freight locomotive fueling took place about 200 feet east of the current Roundhouse Shop building. Bunker C fueling took place about 200 feet further east along the track. Passenger trains were fueled at locations east and west of the current depot.
Information about spills prior to the 1980s is sketchy, but anecdotal accounts tell of personnel walking away from locomotives during fueling and returning to find fuel flowing out the top of tanks.
The Final Draft RI included five spill reports:
¥ December 1983 — About 14,000 gallons of diesel spilled after a coupling failed. The fuel flowed from the pump house to the northern lagoon. Recovery was postponed until February because the ground was frozen and the lagoon was covered with about six inches of snow.
¥ November 1984 — As much as 500 gallons of diesel spilled at the south storage track during fueling operations. Contaminated snow was excavated and transported to the railyard's wastewater treatment system.
¥ June 1987 — About 1,000 gallons of diesel spilled onto the ground during fueling operations. The fuel went into track pans and was contained by sand dikes.
¥ August 1989 — About 2,500 gallons of diesel spilled because of a leak. The fuel was contained in the fueling area.
¥ November 1991 — About 600 gallons of diesel spilled when a switch engine derailed at the fueling facility and punctured a fuel tank. Pooled fuel was cleaned up with absorbent material, and contractors excavated 70 cubic yards of contaminated soil, which was taken to a BNSF landfarm in Whitefish.
Recovery operations
DEQ estimates as much as 110,000 gallons of fuel remains underground at the site. As of September 2008, about 15,447 gallons of free product had been recovered, but further removal has proved difficult. Six gallons were recovered from a well in the middle of the fueling-area plume in 2005; only one gallon was recovered in 2006.
Recovery figures were initially higher. BNSF constructed a 364-foot long interceptor trench in 1973 southeast of the Roundhouse Shop and about 25-50 feet above the river. The trench was lengthened by 100 feet in 1997. By the end of 1999, nearly 1 million gallons of water and contaminants had been removed from the trench.
A star-shaped trench system was constructed in the center of the fueling area east of the Roundhouse Shop in 1988-1989. Two recovery wells inside the trench system removed free product until September 1992. Additional recovery wells were installed nearby in November 1992, and skimming-bailers and belt-skimmers were used in 1993-1995.
BNSF has also used landfarming and thermal treatment of contaminated soil. Petroleum-containing soils from the 1989 trail derailment along Whitefish Lake were hauled to a landfarm at the railyard.
Three years later, about 3,240 tons of contaminated soil from the landfarm was heated to 1,450 degrees by Dustcoating Inc. Another 5,900 tons of contaminated soil removed during construction of a new fueling facility was thermally-treated about the same time.
In 2008, BNSF constructed a spill-control and retention structure at its refueling facility east of the Roundhouse Shop. Kennedy/Jenks also installed an experimental "microwell" recovery system between the Roundhouse Shop and lagoons.
The "microwell" system, which is used in the BNSF railyard in Great Falls, calls for about 35 three-quarter-inch diameter wells installed in three picket fence-like lines across the fueling area plume. The tiny wells are connected together by tubing to a pump and seasonally adjusted for depth to maximize free product recovery.
Figuring out where the fuel ended up after seeping into the ground is not easy and requires studies of topography, hydrology and geology — in addition to drilling down to find out what's there. Numerous monitoring wells and boring sites dot the remediation investigation maps. Some results include:
¥ No oil has been detected at monitoring wells at Lupfer Ave. and First St. and at Miles Ave. and First St. These two wells are in the heart of the Railroad District and not on railroad property.
¥ W-31, a monitoring well about 70 feet north of Miles Ave. and Railway St., on BNSF property near the lagoons, was cited in the 2007 supplemental RI report as where "petroleum hydrocarbons have been detected historically in groundwater samples."
¥ A "petroleum odor" was detected in 2006 in groundwater about 6.5 feet below the surface at oil-boring site GP-29, which is about 50 feet northwest of Miles Ave. and Railway St.
¥ The oil thickness at well W-5A, about 60 feet east of the interceptor trench and about 200 feet west of Miles Ave., has averaged 2.39 feet, reflecting a lobe in the underground plume that extends from the interceptor trench due east toward the Railroad District.
Natural processes
The 74.9-acre BNSF Railway Superfund site is located on up to five feet of fill atop 200 feet of native glaciolacustrine sediments left behind by Ice Age activity and Glacial Lake Missoula. These sediments primarily consist of silt and clay, which has a low permeability that reduces the flow of water and other liquids — including spilled fuel.
Groundwater is found on the site from two to 24 feet below the surface, depending on the season. The average depth is 10-15 feet below grade. Wetlands exist along the northern boundary, and the Whitefish River is about 500 feet from two historic locomotive fueling areas.
According to the Final Draft RI, the underground fuel tends to stay close to where it was spilled on the ground, and the subsurface contaminants appear to be changing due to "natural attenuation." The mass and concentration of petroleum hydrocarbons in groundwater will decrease over time due to physical, chemical and biological processes, the consultants said.
Two processes are key to "natural attenuation," according to Kennedy/Jenks — sorption of petroleum hydrocarbons, so they do not readily move back into groundwater, and intrinsic biodegradation, which results in the breakdown and removal of dissolved petroleum hydrocarbons.
Free product present between the Roundhouse Shop and the lagoons "appears to be weathered, due to its prolonged residence time within the subsurface," the consultants said. Evidence of this process was the low concentrations of BTEX — a combination of benzene, toluene, ethylbenzene and xylene associated with fuel.
Free product floats atop groundwater, which rises and falls seasonally. The thickness of the free product as measured in monitoring wells has "decreased significantly" since 1988, Kennedy/Jenks noted. The thickness of the free product near the center of the plume decreased from 20 feet in 1988 to less than 10 feet in 1998.
Kennedy/Jenks concluded that the petroleum hydrocarbons tended to stay near where they were first spilled and "intrinsic biodegradation is occurring at the facility." Based on monitoring-well data, natural attenuation combined with recovery efforts "have been effective" in controlling underground fuel migration, the consultants concluded.
DEQ's Martin supports that conclusion.
"We're not seeing significant changes in groundwater flow directions or contamination concentration levels or migration to other areas," she recently said. "Subsurface conditions seem to be stable."
Copies of the Kennedy/Jenks remedial investigation reports for 2005, 2006 and 2007 can be found at the Whitefish public library. Additional documents and site maps are available online at www.deq.mt.gov.