The closure of a shared-use road along the Whitefish River may remain in place until July as the BNSF railroad continues to work in the area in response to an oil spill spotted on the river last month near its Whitefish Railyard State Superfund site.
An initial closure of the pedestrian and bike lane between Miles Avenue and Edgewood Place has already been put in place after crews descended on the area on April 11, but the town of Whitefish recently announced that a closure effective April 22 May, accompanied by signage and barriers, would be in place for the same area for about six more weeks while construction work continues to improve an interception system and trench in place along River.
An interception trench in the area was installed by the BNSF in 1973 to try to prevent contaminants from entering the river, and additional clean-up work, including soil excavation, took place between 2009 and 2013 and again in 2019.
In a recent announcement, the city described the closure as including an area from the end of the yard north of the trestle to Miles Avenue. The closure also includes access to the Roundhouse Landing River, where a boat launch has been removed as part of the ongoing response. The BNSF previously called the burst discovered on April 10 a small one, and the Montana Department of Environmental Quality said no measurable amount of oil was found in the river.
This announcement indicated that BNSF was working with Montana DEQ on the design of an improved interceptor trench, including a deeper trench, to prevent low groundwater levels from bypassing the interceptor system that is in place to try to prevent contaminants from entering the river.
The current interceptor trench is oriented east and west, lined with poly sheets and backfilled with crushed rock and gravel. Drainage pipes in the trench supply water to a central sump pump which sends water through an oil-water separation system. According to DEQ, work underway to improve the system will include placing a second, deeper trench closer to the river on the west side of the existing trench which will also connect to the existing sump system.
In a progress letter sent to the Montana DEQ earlier this month, a Kennedy/Jenks Consultants environmental engineer who works on behalf of BNSF, described how “initial response activities indicate that levels of abnormally low water were likely allowing affected groundwater to pass under the trench,” and the letter goes on to state that the temporary sump pumps will continue to remove groundwater until a permanent solution can be implemented.
The Town of Whitefish similarly described that the BNSF determined the burst was caused by abnormally low groundwater levels “allowing affected groundwater to pass under the existing interceptor trench.”
Sump pumps transporting water for treatment through an oil-water separator are only part of the temporary measures put in place so far. A dam containing absorbent materials was also installed along the shore near the splinter, along with a sediment fence, and a watertight cofferdam was also put in place to trap water in the area along the shore so that it can be drained and the ground can be excavated. Contaminated sediment had previously been found 4 feet deep in an area about 10 feet by 8 feet, according to DEQ. According to the Kennedy/Jenks letter to the DEQ, the excavated sediments were backfilled with clean, low-permeability soils near and at the river, and capped with rounded river rocks.
The 78-acre Superfund site has a history of contamination associated with rail yard discharges related to refueling repair, rail operations and transporting sewage to the lagoons, and rail usage history predates BSNF ownership and dates back to 1903. Chemicals that have been identified in groundwater contaminated soils associated with the Superfund site include petroleum products, polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) , volatile organic compounds (VOC) and heavy metals.