JANUARY 19, 2022 - ADMINISTRATIVE SETTLEMENT AGREEMENT AND ORDER ON CONSENT FOR REMOVAL ACTIONS;
g. On July 28, 2021, AZP initiated the removal and replacement of the liners
within the raffinate pond. After removing the liners, AZP discovered a discoloration in the
underlying substrate surface which suggested a potential release from the pond. AZP collected
samples of the substrate material (sand and gravel) at two locations. A small amount of liquid
was encountered during sampling at one of the locations. The samples were sent to AZP?s onsite
QA/QC laboratory and a third-party laboratory for analysis. The liquid sample exhibited a
pH less than 2 standard units (s.u.) and elevated metal concentrations. The presence of elevated
metals in substrate material beneath the pond suggested material had leaked from the pond.
h. On July 29, 2021, AZP received the preliminary results from its on-site
laboratory which indicated elevated levels of metal concentrations.
i. Upon discovering the evidence of a potential release of hazardous
substances from the raffinate pond, Respondent notified the National Response Center of the
release on July 29, 2021.
j. This discovery of the potential release from the raffinate solution pond
triggered the investigation of the depleted solution pond and the maintenance pond. To facilitate
this investigation, AZP converted the Western Ponds to storage tanks with the liner system in
each pond serving as secondary containment.
k. On July