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Sand Island Wastewater Treatment Plant



Sand Island Wastewater Treatment Plant Environmental Site Assessment and Risk Investigation


Project Highlights:

Project Description:

High levels of PCB contamination were found in soil in one localized area of the Sand Island Wastewater Treatment Plant (WWTP), which prompted a Toxic Substances Control Act (TSCA) cleanup. This entailed conducting Phase I and II Environmental Site Assessments (ESAs), a Human Health Risk Assessment, as well as documentation for all remedial procedures.

To accomodate ongoing City and County of Honolulu construction activities related to plant upgrades, Environet conducted the Phase II ESA in separate phases. This entailed soil and groundwater data collection, which were also included in the Human Health Risk Assessment. A notification report for self-implementing cleanup (under TSCA 761 Part A) detailed confirmation sampling requirements, excavation design, and other remedial procedures, and was submitted to USEPA Region 9 for approval. Negotiating this report with the USEPA and also the DOH in a short timeframe allowed the City to proceed with construction with minimal delays.

For remediation of the PCB-impacted areas, Environet prepared plans and specifictions, as well as construction oversight, review of waste manifests and sampling results, and review of the closure report. A total of 100 cubic yards of PCB-contaminated soil was removed and disposed at a TSCA landfill on the mainland. In addition, a soil management plan was provided by Environet for future reuse/remedial/disposal alternatives, should any contaminated soil be found still present at the site.