AltEn Site Stabilization Update

The below information has been provided in an effort to help keep the community informed on a more frequent basis about progress at the AltEn site. 

Ever since AltEn ceased operations at its facility in Mead in 2021, the AltEn Facility Response Group (FRG) has been voluntarily working under the guidance of the Nebraska Department of Environment and Energy (NDEE) to stabilize the AltEn site and develop a Remedial Action Plan (RAP) for the site. The FRG’s top priorities have been and continue to be to help ensure the safety of the surrounding community and environment. To-date, there has been no evidence of impacts to local drinking water.

The FRG is working diligently with the NDEE to identify the most effective and safest methods to address the current environmental conditions on the AltEn site. The remedial action plans (RAP) will recommend remediation for components remaining on-site, including wastewater, sludge, and wet cake.

May 31, 2022

AltEn Site Stabilization Update

FROM AltEn Facility Response Group

Situation Background

  • The AltEn Facility Response Group (FRG) consists of six companies who had agreements with AltEn’s facility outside Mead, Nebraska, to supply seed for ethanol production.
  • AltEn failed to fulfill its obligations to each of the FRG companies.
  • Seed companies have been working to stabilize the site since February 2021, and the FRG was formed in the Spring of 2021.
  • The FRG has worked voluntarily under the direction of the Nebraska Department of Environment and Energy (NDEE) to help ensure the site is secure and stabilized while next steps for the site are determined by the NDEE.
    • All current work is being undertaken via a Memorandum of Agreement through Nebraska’s Voluntary Cleanup Program (VCP).

Companies Acted to Secure Site & Ensure Community Safety
  • When it became obvious that AltEn was not going to fulfill their obligations and respond to concerns, the companies came together as the FRG to respond quickly to manage immediate concerns relating to lagoon water and wet cake, including stormwater management.
  • The FRG continues to focus on stabilization of the site while also preparing the remedial action plan (RAP), which will recommend remedial actions, as well as the interim remedial action report (IRAR), which will document site stabilization activities to date.
  • All work has focused on securing the site to help ensure the safety of the surrounding community and environment.
FRG Addressed Wet Cake Runoff& Removed Excess Water
  • Over the last year, the FRG has worked to consolidate the wet cake on-site to control runoff, while also removing excess water from the on-site lagoons to better ensure their safety.
  • The below photos are examples of the wet cake, lagoons and emergency pond –all of which are now vastly improved.
Aerial View of the Site, Pre-FRG Activity

The wet cake from the central and east wet cake areas has now been consolidated in the northwest wet cake pile, along with the underlying soil that had been in direct contact. Soil in the former central and east wet cake areas has been replaced with clean soil.

Reduced Water Levels in Lagoons; Emergency Pond Cleaned and Relined
  • Starting in February 2021, the companies constructed an on-site water treatment system and 29 million gallons of above-ground temporary storage tanks to begin moving, treating and storing water from the emergency pond and lagoons.
  • Water levels in the lagoons are now within safer operating levels and are regularly inspected for preventive maintenance.
    • A multi-stage treatment process is being used to reduce pesticide residues to very low levels, which will result in a fraction of EPA-approved agricultural rates for land application.
  • The materials in the emergency pond have now been completely removed, and the FRG has completely replaced the lining of the pond to provide additional water storage capacity.
  • The construction of two treated water ponds to expand on-site capacity for treated water is complete. The ponds are now lined and NDEE-permitted.
  • In April 2022, the FRG committed to continue treating the lagoon water. As of May 25, 2022, a total of 18.2 million gallons of water have been treated.

Successful Land Application of Treated Water Sets Stage for Fall 2022

  • In Spring 2022, 9 million gallons of treated water was land-applied to local fields.
    • The water was tested and confirmed to comply with approved NDEE thresholds for land application.
    • The treated water safely provided moisture and nutrients necessary for healthy crop growth at no cost to landowners, while also helping recycle water in an area where it’s badly needed.

In addition to the lagoons, the FRG removed materials previously being held in the emergency pond and has completely replaced the lining of the pond to provide additional water storage capacity. The FRG is currently evaluating use of the emergency pond for sludge management.

Wet Cake Consolidated & Temporarily Covered

  • The FRG has prioritized capturing any water seepage from the consolidated, covered wet cake pile and has installed a perimeter drainage system to direct seepage for collection and treatment at the on-site water treatment system.
    • This system reduces the potential of this moisture to move into the ground.
  • The FRG installed the wet cake pile drainage and cover system using Posi-Shell, as approved by the NDEE.
    • The purpose of the temporary Posi-Shell covering is for waste containment, odor control and to prevent contact between the wet cake and any precipitation, preventing the generation of additional contaminated stormwater.
    • This type of Posi-Shell layer has been used for similar remedial projects over the last 15 years and has been proven effective for these purposes.
    • The coating is safe for both the surrounding community and the environment.
    • The Posi-shell manufacturer visited the site the week of Apr. 24, 2022, and reported that the application was a complete success and the Posi-shell system is operating as well as or better than intended.


Diagram of Wet Cake Covering

Active Environmental Monitoring & Controls in Place

  • Per NDEE’s direction, the groundwater around the site is being monitored regularly by AltEn.
    • The geology of the site and soils underneath it, a thick layer of clay 15-20 feet deep, have worked to prevent vertical migration of wet cake seepage or untreated lagoon water.
  • As the FRG continues to maintain the lagoon water levels and prevent contact between stormwater and the wet cake, the potential for groundwater impacts will be reduced.

Monitoring, Sampling & Analyses Continues on the Northwest Lagoon

  • The FRG is continuing to monitor and sample all groundwater monitoring wells, the lagoons and two deep supply wells.
  • Recent NDEE data indicated the presence of certain pesticides in the groundwater sample taken from one geoprobe location (known as SP-2).
    • The constituents found in that sample were not consistent with those found in the northwest lagoon water or any other monitoring well, including the immediately downgradient well.
    • The FRG is installing a new permanent monitoring well at the SP-2 location in June.
    • The FRG has installed transducers near the lagoons that automatically collect water level data every 15 minutes.
  • Test results throughout the AltEn site do not indicate the presence of constituents in the groundwater above NDEE groundwater thresholds for the protection of human health.
Moving Forward
  • The FRG has worked to keep the Mead community and environment safe over the last year. This is our top priority.
  • We have also made it a priority to maintain regular communication with the NDEE and the community.
    • We have participated in regular update sessions for community leaders and have provided updates to the public.
  • We are continuing to stabilize the site as we work under the oversight of the NDEE to develop the remedial action plan (RAP), which we anticipate being submitted to NDEE in late July. As part of the Voluntary Cleanup Program (VCP), the FRG is preparing:
    • Remedial action plan (RAP), which will provide recommendations for NDEE consideration that address wet cake, sludge and lagoon water.
    • Interim remedial action report (IRAR), which will describe the emergency response and site stabilization activities to-date.