Public Notice Information
IWM
62744
LP Gill Municipal Solid Waste Landfill
Jackson
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Proposed remedial action
November 21, 2019
December 21, 2019

Public Notice
Proposed Remedial Action Decision
L.P. Gill Landfill
Page 2 of 2
PUBLIC NOTICE
PROPOSED REMEDIAL ACTION DECISION
L.P. GILL LANDFILL

Notice is hereby given pursuant to Nebraska Title 118 – Ground Water Quality Standards and Use Classification Chapter 11, that the Nebraska Department of Environment and Energy (NDEE) is proposing final cleanup levels and remedial action at L.P. Gill Landfill. This proposed determination is in accordance with Title 118, Appendix A. L.P. Gill Landfill is located approximately 2.5 miles north of Jackson, Nebraska on Highway 20. The legal description of the landfill is Parts of Sections 20, 21, 28, and 29, Township 29 North, Range 7 East of the 6th Principal Meridian, Dakota County, Nebraska.

The groundwater at this site has been contaminated as a result of a release from the landfill. The NDEE has assigned the groundwater pollution event at this site a Remedial Action Class-2 (RAC-2). RAC numbers are used to prioritize the groundwater pollution events with one (1) being the highest priority and three (3) being the lowest priority. The proposed final cleanup levels in groundwater are shown in Table 1. The NDEE is proposing the following remedial actions: long-term groundwater monitoring, landfill cap maintenance (following closure of the landfill), and institutional controls (to restrict groundwater use). In addition, contingency measures for increased groundwater sampling or other actions will be in place should groundwater contamination migrate beyond its current extent.



Any person may receive additional information, submit written comments regarding the proposed actions, or request a public hearing, in writing, on or before December 21, 2019. A request for hearing must state the nature of the issues to be raised and all arguments and factual grounds supporting such position. If the Director grants a public hearing, the hearing will be advertised by public notice at least 30 days prior to its occurrence. Comments and requests should be mailed to:
David Haldeman
Land Management Division
Nebraska Department of Environment and Energy
P.O. Box 98922
Lincoln, NE 68509-8922

The public notice and fact sheet are available online at http://dee.ne.gov/ by selecting “Public Notices,” or by accessing the Enterprise Content Management Portal at https://ecmp.nebraska.gov/ publicaccess/viewer.aspx?&MyQueryID=340 using Facility Number 62744 and Program IWM. Please notify the NDEE if alternate formats of materials are needed by December 6, 2019. Individuals requiring special accommodations or alternate formats of materials should notify the NDEE by calling (402) 471-2186. TDD users should call (800) 833-7352 and ask the relay operator to call the NDEE at (402) 471-2186. Further information may be obtained from Mike Felix, Remediation Section, at (402) 471-4210.






Fact Sheet
Proposed Remedial Action Decision
L.P. Gill Landfill
Page 3 of 3
FACT SHEET
PROPOSED REMEDIAL ACTION DECISION
L.P. GILL LANDFILL

The Nebraska Department of Environment and Energy (NDEE) is providing public notice of its intent to propose final cleanup levels and remedial action at L.P. Gill Landfill. This fact sheet provides background information on the site, a summary of groundwater contamination, a description of the proposed remedial action, a description of the public participation procedures, and the NDEE contact person.

Site Location: L.P. Gill Landfill is located approximately 2.5 miles north of Jackson, Nebraska on Highway 20. The legal description of the landfill is Parts of Sections 20, 21, 28, and 29, Township 29 North, Range 7 East of the 6th Principal Meridian, Dakota County, Nebraska.

Groundwater Contamination: The groundwater at this site has been contaminated as a result of a release from the landfill. The primary contaminants of concern (COCs) detected in the groundwater are metals; however, low levels of volatile organic compounds have also been detected in groundwater at the landfill. The NDEE compared contaminant concentrations detected in the groundwater to the Maximum Contaminant Levels (MCLs) and Nebraska Voluntary Cleanup Program (VCP) Remediation Goals (RGs) to determine the significance of the contamination. MCLs are established by Nebraska Title 118 – Groundwater Quality Standards and Use Classification.

The nature and extent of the groundwater pollution occurrence is confined to the site, and offsite migration has not occurred. The COCs that prompted remedial action at the landfill include arsenic and cobalt. Arsenic was identified as a statistically significant increase (SSI) above the MCL in monitoring well MW-3A, and cobalt was detected as an SSI above the VCP RG in monitoring wells MW-3A and MW-15. Monitoring wells MW-3A and MW-15 are both screened within a loess/marl unit, which is characterized by good water quality but poor permeability, with groundwater flow generally to the north. Immediately north (downgradient) of monitoring wells MW-3A and MW-15 is monitoring well MW-19A; neither arsenic nor cobalt have been detected above the laboratory reporting limit in this well since 2015. Based on the groundwater results in monitoring well MW-19A, the NDEE considers the nature and extent of contamination to be sufficiently characterized.

The potential exposure pathway is ingestion, dermal contact, and inhalation of contaminated groundwater; however, contamination is limited to an upper impacted hydrologic unit and is not migrating offsite. There are no domestic wells within the area of contamination.

Groundwater Remedial Action Class: The NDEE assigns a Remedial Action Class (RAC) to a groundwater contamination event to determine the importance of remedial action based, in part, on the use of the groundwater in the area (Title 118, Appendix A, Step 8). Groundwater that is being used as a public drinking water supply is assigned the highest remedial action class of RAC-1. The NDEE typically requires extensive cleanup of groundwater that is classified as a RAC-1. When the use of groundwater in the area is more limited, the groundwater is assigned a remedial action class of RAC-2 or RAC-3. Generally, groundwater cleanup will be less extensive for these classifications.
The pollution event for this site has been classified as a RAC-2, due to the fact that there are no domestic wells within 4,000 feet of monitoring wells MW-3A and MW-15. Aerial photographs indicate three areas to the north and one area to the west of the landfill where residents could have unregistered domestic wells; however, these residents are all located at least 2,000 feet from monitoring wells MW-3A and MW-15. The facility has a deep water supply well located just over 800 feet southeast of monitoring well MW-3A; however, the water supply well is upgradient of the area of contamination and acquires water from a lower hydrologic unit.

To date, only two COCs, arsenic and cobalt, have exhibited confirmed SSIs above MCLs or VCP RGs. However, there are several contaminants that have exhibited confirmed SSIs below MCLs or VCP RGs. It is expected that the proposed remedial action decision for arsenic and cobalt would likely also apply to any additional contaminants that are reported as SSIs above MCLs or VCP RGs in the future. Therefore, the NDEE is proposing final cleanup levels for all contaminants that have exhibited a confirmed SSI during any of the past three semi-annual groundwater sampling events; and vinyl chloride, which is a breakdown product of trichloroethene. The proposed final cleanup levels are shown in Table 1.



Proposed Remedial Actions: The NDEE is proposing the following remedial actions: long-term groundwater monitoring, landfill cap maintenance (following closure of the landfill), and institutional controls (to restrict groundwater use). In addition, the landfill will need to address contingency measures should groundwater contamination migrate beyond its current extent. Long-term groundwater monitoring will assure early detection of any significant changes and demonstrate achievement of final cleanup levels within a reasonable period of time. Landfill cap maintenance is a presumptive remedy that includes covering exposed waste, establishing adequate drainage and vegetation, and maintaining vegetation to inhibit the formation of leachate. Institutional controls will include annually assessing whether new wells have been installed near the landfill, which would change the RAC designation and require additional sampling. In addition, contingency measures for increased groundwater sampling or other actions will be in place should groundwater contamination migrate beyond its current extent. Financial assurance will be required for the selected remedy.

Public Participation Procedures: You may receive additional information, submit written comments regarding the proposed actions, or request a hearing, in writing, on or before December 21, 2019. If you request a hearing, you must state the nature of the issues to be raised, present your arguments, and provide facts to support your position in writing to the NDEE. If the Director grants a public hearing, the hearing will be advertised by public notice at least 30 days prior to its occurrence. Comments and requests should be mailed to:
David Haldeman
Land Management Division
Nebraska Department of Environment and Energy
P.O. Box 98922
Lincoln, NE 68509-8922

Contact: The public notice and fact sheet are available online at http://dee.ne.gov/ by selecting “Public Notices,” or by accessing the Enterprise Content Management Portal at https://ecmp.nebraska.gov/ publicaccess/viewer.aspx?&MyQueryID=340 using Facility Number 62744 and Program IWM. Please notify the NDEE if alternate formats of materials are needed by December 6, 2019. Individuals requiring special accommodations or alternate formats of materials should notify the NDEE by calling (402) 471-2186. TDD users should call (800) 833-7352 and ask the relay operator to call the NDEE at (402) 471-2186. Further information may be obtained from Mike Felix, Remediation Section, at (402) 471-4210.