More than 4 million gallons of a mixture of fresh water, brine and oil have been pumped from the area affected by the largest saltwater spill of North Dakota's current energy boom, according to a report issued Monday by the Environmental Protection Agency.
The report provides an overall assessment on the nearly 3 million-gallon spill of saltwater generated by oil drilling that leaked from a ruptured pipeline that operator Summit Midstream Partners LLC detected on Jan. 6. It remains unclear exactly when the spill occurred and what caused it.
The spill happened in Marmon, about 15 miles north of Williston, and primarily contaminated the Blacktail Creek. Saltwater also reached the bigger Little Muddy River and the Missouri River.
Saltwater, known as brine, is an unwanted byproduct of oil and natural gas production that is much saltier than sea water and may also contain petroleum and residue from hydraulic fracturing operations. Some previous saltwater spills have taken years to clean up.
The EPA's report also states that underflow dams — which allow clean water to flow freely underneath and can contain materials that float on the water's surface — are being built in case water levels rise.
The mixture of fresh water, brine and oil that has been pumped from several locations along Blacktail Creek is being transported to a well site to be injected underground. Saltwater is usually pumped underground for permanent storage from a network of pipelines that extends to hundreds of disposal wells in the western part of the state.
The latest spill is almost three times larger than one that fouled a portion of the Fort Berthold Indian Reservation in July. Another million-gallon saltwater spill in 2006, near Alexander, is still being cleaned up nearly a decade later.
Democratic state lawmakers have promised to file legislation that would mandate additional monitoring and safeguards for pipelines that carry briny oilfield wastewater.
Democrats said the legislation may be similar to what a Republican lawmaker pushed two years ago but was defeated after resistance from oil companies, which argued the additional monitoring would be too expensive.
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