Midwest AG Big Sioux River Pesticide Spill

Notices  Posted Category
Site Description 6/28/2019 01 Background

On June 26, 2019 EPA received a call from the South Dakota Department of Environment & Natural Resources (DENR) requesting assistance with a 900-gallon pesticide spill resulting from the rollover of a flatbed tractor trailer. The trailer had rolled over next to the Big Sioux River. The tractor trailer also ruptured the diesel tanks causing a discharge to the road ditch adjacent to the River. The State Patrol, the Sheriff’s Department, and County fire and EMS all arrived on Site to assess the situation. A containment berm was constructed around the area of the crash to help contain spill contaminants by the county.

 

An EPA Region 8 On-Scene Coordinator (OSC) and START contractor were deployed and arrived on-scene on June27, 2019. The OSC will meet with the South Dakota Department of Environment & Natural Resources (DENR)  to continue to assess and provide oversight.



Initial Response 6/28/2019 01 Background

Hamlin County emergency response personnel responded to the tractor trailer rollover into a ditch adjacent to the Big Sioux River. The County constructed an earthen berm to prevent contamination from discharging from the ditch area into the Big Sioux River. The Potential Responsible Party (PRP) deployed an emergency response contractor to initiate the removal of contamination and diesel fuel. The PRP contractor reinforced the berm, deployed absorbent material and containment boom.

 

EPA OSCs along with the State and County are on scene providing oversight and technical assistance to the PRP contractor.



Response Objectives 6/28/2019 02 June 26 - June 29

1. Coordinate with the State and potentially impacted communities on response operations.

2. Provide technical assistance and guidance to the PRP.

3. Mitigate and contain contamination from entering the Big Sioux River.

 



Response Operations 6/28/2019 02 June 26 - June 29

EPA deployed START contractors to sample surface soil and surface water. Surface water samples are targeted to assess the potential impacts of the contaminates within the Big Sioux River. State and County continue to work with EPA to assist and advise the PRP contractor on containment and removal of the contamination.

 



Planned Activities 6/28/2019 02 June 26 - June 29

EPA will continue to work with the State, County and PRP contractor to continue removal operations. The PRP contractor will construct an additional berm to alleviate surface water inflow into the ditch area.

 

Once the ditch is dry by evaporation and attenuation, the PRP will conduct a soil removal to remove contamination left in place as necessary.

 

EPA will conduct soil and surface water sampling to confirm status of removal action performed by the PRP contractor.



Response Objectives 7/2/2019 03 June 30 - July 2

1. Coordinate with the State and potentially impacted communities on response operations.

2. Provide technical assistance and guidance to the PRP.

3. Provide monitoring of any impacts to the Big Sioux River from berm breach.



Response Operations 7/2/2019 03 June 30 - July 2
On the morning of July 2, 2019, the containment berm was breached by rising flood waters from the Big Sioux River. The Big Sioux River has reached flood stage and is expected to crest some time over the next day. Additional precipitation within the watershed is forecasted for the next several days. EPA has deployed START contractors to sample for any potential impacts downstream. EPA is working with the State and Local communities on monitoring and communicating potential impacts from the breach.

Planned Activities 7/2/2019 03 June 30 - July 2

EPA will monitor for any potential impacts downstream from the release due to the berm breach. 

 

Once the Big Sioux River has receded, EPA will work with the State and PRP to establish further removal actions and conduct a soil removal of the impacted area at the crash site. 

 

SITE UPDATE as of July 23, 2019 - By July 10, 2019, flood waters from the Big Sioux River had completely crested the berm and the area of the crash site was completely inundated, while the majority of the berm was submerged. As of July 19, 2019 flood waters had receded exposing portions of the berm, but were expected to rise again. Surficial soil and surface water samples collected by both the EPA and PRP before and after inundation of the crash site by flood waters demonstrated that contaminant levels were below levels of concern in the Big Sioux River.