Tesoro Begins Cleanup of Massive Oil Pipeline Spill in North Dakota (PHOTOS)

Though the Keystone XL pipeline has been delayed due to popular backlash, oil and related hazardous materials continue to flow through the United States on trains and through pipelines. Increasingly these pipelines leak, contaminating the surrounding neighborhoods, rivers, and wheat fields with hazardous cancer-causing chemicals like benzene.

Last year in North Dakota, a Tesoro pipeline carrying oil obtained through fracking the Bakken shale ruptured in a farmers field, spilling an estimated 20,600 barrels over a seven acre area, one of the largest land based spills in US history. The spill was caused by a leak the size of a quarter coin, and went undetected by Tesoro until the farmer sank his combine into an oil sodden field. Tesoro has recently begun a two year cleanup, during which they will use a "thermal desorbtion" process to burn away oil from the area.

Here are some things you might not know about Tesoro's pipeline spill:

The scale of the Tesoro spill was huge, equaling the total for all spills in North Dakota over the past 10 years combined.

Picture taken shortly after the spill was discovered in October, 2013

Through January, 2014, 1,260 gallons of oil leached from the ground per week.

Oil can be seen in ditches dug by Tesoro. These ditches collected over 1,200 gallons of oil per week for months after the spill was discovered.

The oil seeped down 42 feet below the surface and the entire seven acre area will be excavated to depths of more than 30 feet

The first 30 foot pit is visible in the upper left side of the photo, the entire area will eventually be dug out and burned in the incinerator at lower right.

The contaminated soil is then sent through the thermal desorbtion process -- during which the entire area is excavated and baked in an onsite oven, which will attempt to burn hydrocarbons from the soil.

A closer look at the incinerator meant to burn hydrocarbons out of the soil during the "thermal desorbtion process."

However, "full remediation" will only take place down to 8 feet. This means significant amounts of contaminants (up to 500 ppm) will remain in the soil and water pockets under the wheat field. The root systems of wheat can penetrate 7 feet down, depending on the type of wheat.

The rapid spread of high volume hydraulic fracturing has led to a massive buildup in oil and gas infrastructure, including hundreds of thousands of new oil and gas wells, as well as thousands of miles of new pipelines. However, the regulatory structure has failed to keep pace with the boom. In fact, even as pipeline spills have increased, the Pipeline and Hazardous Materials Safety Agency (PHMSA), the agency that regulates pipelines, has cut staff by nine percent.

As Katie Valentine of Think Progress points out:

"More than 120,353 barrels of hazardous liquids, including crude oil and other petroleum products, spilled in 622 incidents in 2013, more than double the 45,934 barrels spilled in 570 incidents in 2012."

Early July of this year, an oil industry waste pipeline ruptured on the Fort Berthold Indian Reservation, occupied by the Mandan, Hidatsa and Arikara tribes. The pipeline spilled over 1 million gallons of contaminated water near Bear Den Bay, a tributary of Lake Sakakawea.