Longhorn Army Ammunition Plant

Environmental Restoration Program


Site Description/History

LHAAP-04, also known as the Former Pilot Wastewater Treatment Plant, is located in the central portion of LHAAP at the northwest corner of 6th and 60th Streets near the former fire station and covers approximately 0.5 acre. LHAAP-04 began industrial wastewater treatment operations in 1984 and historical operations resulted in environmental impacts to soil and groundwater. Demolition of the Former Pilot Wastewater Treatment Facility structures, tanks, and piping, and the disposal of associated wastes were completed in the summer of 1997 as part of Resource Conservation and Recovery Act closure of the plant.

Remediation Activities

Numerous sampling events were conducted from 1993 through 2008 to identify contamination from past operations and its impact to soil. In coordination with the U.S. Environmental Protection Agency (USEPA) and the Texas Commission on Environmental Qualtiy (TCEQ), Army implemented a non-time-critical removal action in 2009 through which a total of approximately 3,406 cubic yards of soil contaminated with perchlorate and mercury were excavated and transported off site, eliminating the principle threat at the site.

Final Record of Decision (ROD) was signed by EPA in March 2017. The selected remedy included in situ bioremediation (ISB) to reduce perchlorate concentrations in groundwater to meet the cleanup level, Long Term Monitoring (LTM) of groundwater, and Land Use Controls (LUCs). Remedial Design/Remedial Acton Work Plan (RD/RAWP) was completed in April 2019. In situ bioremediation was completed in November 2019 and a Remedial Action Completion Report (RACR) was completed in April 2021.

Contaminants of Concern

Perchlorate in groundwater

Current Phase

Post-ISB Remedial Action Operation (RA-O) groundwater monitoring is continuing.

Future Phase

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