More diesel cleanup wells to be shut down in Mandan
The Mandan Remediation Trust on Tuesday approved shutting down 68 more collection wells used for recovery of a diesel spill that was caused by the BNSF Railway. Consultant Leggette, Brashears and Graham Inc. will study which and when the remaining wells can be shut down and plugged over the next one to three years. The MRT approved a $20,000 retainer fee for LBG to collect data about which wells sites can be abandoned.
Last month, the state Health Department said the city can start planning a near complete shutdown of the wells and leave a few monitoring wells. Some 1 million gallons of product have been recovered in liquid diesel, vapor, gasoline vapor, diesel vapor, free-phase liquid fuel and other forms of the spill contamination since 2006.
However, fluctuating ground water levels may factor into how many of the wells are kept active or monitoring future diesel product risks.
The wells approved for de-commissioning Tuesday are located north of Main Street between Collins Avenue and Second Avenue and south of Main Street near the rail tracks, said Francis Schwindt, a member of the MRT. Affected locations include wells near the Morton County Courthouse, the Law Enforcement Center and Library Square and apartments near the LEC. South of Main Street, another 13 wells will be shut down in the Heritage Plaza area. A handful of wells will be kept running in these areas for collection and monitoring purposes.
Thirty wells had been shut down before Tuesday’s decision, according to the MRT members.
“With the action we’re taking today, we no longer need to actively run those portions of the system,” Schwindt said. “We can shut the vacuum systems off and discontinue use. Probably next spring, we’ll physically plug them with a bentonite grout.”
Mandan City Administrator Jim Neubauer, a member of the MRT, said the latest shutdown means about one-third of the 285 collection wells have been rendered inactive.
The MRT pays for claims against and cleanup costs for diesel contamination issues through BNSF’s $24 million settlement. About $7.4 million remain in the fund. A majority of the fund has been used to pay LBG for creating the downtown network of collection wells, monitoring wells and a facility for processing the diesel waste product collected. It costs about $300,000 per year to run the system. The trust fund also helped pay for a water-diesel separation system at the Law Enforcement Center in Mandan.
The diesel spill was first detected in 1985 when digging began for the Law Enforcement Center. BNSF extracted some 600,000 gallons of liquid product, but other contamination remained. LGB was hired by the MRT to collect the remaining diesel product.
Schwindt said once the wells are shut down and filled, contractors may do what they wish with the completed wells. The MRT will not require inactive wells remain in place.
Neubauer said funds left over from the settlement money may be transferred to the Supplemental Environmental Trust Fund. The special fund is used for downtown projects and park improvements.
The MRT also is studying how it might set up a long-term insurance policy to protect the city if future diesel contamination was discovered after the wells are shut down. “Rather than keep a large amount of the trust fund money intact, you could keep an insurance policy that would cover something that may come up, something unknown,” Neubauer said. “The insurance fund would then kick in to fund any unknown liability. Thereby, you free up the remediation trust fund money to do with whatever the trust and city decide.”
By LeAnn Eckroth, Lee News