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.
OCTOBER 3, 2022
Groundwater Monitoring Updates
NDEE has shared the results of its most recent groundwater sampling, which confirms that water in off-site wells continues to meet human health safety benchmarks. NDEE and the FRG have been conducting additional groundwater testing following the detection of active ingredients in one groundwater well adjacent to the Northwest AltEn lagoon. The FRG has installed 4 additional monitoring wells on the AltEn site for expanded monitoring purposes and NDEE has installed an additional two monitoring wells. The FRG as well as the NDEE have sampled all 10 wells on the AltEn site. The NDEE has also sampled the 48 off-site wells. MW-5, the well adjacent to the Northwest AltEn lagoon, continues to be the only groundwater monitoring well where constituents present in the lagoon water appear to have been materially present in the groundwater sample. NDEE testing has consistently shown no evidence of impacts to local drinking water.
On October 17, the FRG anticipates installing the final deep monitoring well. The FRG will conduct an additional round of sampling of the on-site wells following installation of that well.
The AltEn site is downgradient from the Village of Mead and the majority of off-site wells that are downgradient from the AltEn site have been sampled multiple times with ongoing monitoring. The below map shows groundwater sampling locations in the NDEE monitoring program:
The human health safety benchmarks used for comparison to groundwater concentrations were obtained from the Environmental Protection Agency’s (EPA) Human Health Benchmark for Pesticides and the NDEE’s Voluntary Cleanup Program (VCP) Remedial Goals. Both agencies use a protective approach which incorporates conservative exposure assumptions and the latest scientific information. This allows the agencies to develop risk-based concentrations that are protective of human health. These are conservative screening values, in addition, site-specific values may be developed as part of the ongoing Remedial Action Plan (RAP) development based on site specific exposure assumptions. The FRG and NDEE continue to monitor and assess groundwater conditions. As shown in the map, only one well out of 58 sampled contains concentrations above those benchmarks, and that well is on the AltEn site, downgradient from Mead. NDEE testing results continue to show no evidence of impacts to local drinking water.
Submission of the Water Remedial Action Plan
On September 12, the FRG submitted the Water RAP to the NDEE. Currently, the Water RAP is undergoing review by NDEE. After the NDEE conditionally approves the RAP, they will issue the report for a 30-day public comment period, and afterward host a public meeting, the date of which will be determined by NDEE.
Concurrently, the FRG is continuing to work through the regulatory steps necessary to apply treated water to nearby fields this fall as a nutrient-rich benefit for crop health.
- The detailed Water RAP can be found at AltEnInfo.com. The proposed remedy consists of the following components: Treating an estimated 115 million gallons (Mgal) of process water (remaining as of August 2022), and stormwater that accumulates in the lagoons and the Emergency Pond
- Optimizing the water treatment system
- Storing treated water in the Treated Water Storage Ponds until land application can be performed
- Applying treated water to local agricultural fields, as requested and subject to approval by local landowners and the NDEE
- Temporary storage of sludge from the water treatment system in the former Emergency Pond
Potential Solutions for Remaining Wet Cake and Sludge Solids
Now that the Water RAP has been submitted, the FRG continues its focus on assessing site conditions and gathering additional data about the solids at the AltEn site. Several options for treatment of the wet cake and sludge are being evaluated by the FRG for the Solids RAP, including:
- Solidification & On-Site Containment
- On-Site Thermal Treatment (not incineration)
- Solidification & Off-Site Landfilling
- Off-Site IncinerationThese will be discussed with the community and included in the Solids RAP.
These will be discussed with the community and included in the Solids RAP.
The Posi-Shell cover that was recently repaired remains useful for waste containment, odor control, preventing air emissions, and eliminating contact between the wet cake and any precipitation, preventing the generation of additional contaminated stormwater.
The FRG continues to work diligently with the NDEE to identify the best, safest, and quickest method to remediate the water and solids at the AltEn site. The FRG is evaluating additional data about the site conditions and materials to best inform its recommendation for the Solids RAP, which we intend to submit to NDEE before the year’s end. The FRG’s top priorities
continue to be working to secure the site to support the safety of the surrounding community and environment.
