East Parking Lot
Manufactured Gas Plant Remediation

 

Ninyo & Moore was retained to provide environmental services relative to the East Parking Lot Remediation project in an active downtown redevelopment area. The project consisted of the remediation of 35,000 cubic yards of manufactured gas plant (MGP) waste and impacted soil by excavation and off-site disposal. Project features included precharacterization by the landfill for disposal allowing highly-efficient excavation and disposal methodology, aggressive air monitoring and vapor/odor suppression techniques, and public information program to keep the community up to date. MGP waste containing benzene, naphthalene, and other polyaromatic hydrocarbons (PAHs), had been disposed of at the site from the late 1800s through the 1930s (the period of operation of the power station MGP by the utility's predecessor). The site was under a Cleanup and Abatement Order (CAO), which required the cleanup of groundwater to specified levels. Ninyo & Moore performed site assessments of the East Parking Lot, evaluated cleanup levels presented in the CAO, performed a screening level feasibility analysis, and prepared a Corrective Action Work Plan for remediating the source zone impacts. Working closely with the owner we assisted in the preparation of the remedial contractor bid request, assisted in the evaluation of contractor submittals, and provided responsible oversight and work plan compliance documentation, assistance with sampling, and interface with the lead regulatory agency. We also prepared and released weekly public notification messages related to community health and safety air monitoring at the site and project progress, and provided litigation support to the owner. We were instrumental in working with the regulatory agencies to revise/update COPCs and cleanup levels based on findings of investigations subsequent to issuance of the CAO. We constructed 17 groundwater monitoring wells during our site work, and performed quarterly groundwater sampling for post-remedial compliance with the CAO. Based on the monitoring results, we obtained approval for the abandonment of 12 of the 17 groundwater monitoring wells which greatly benefits site redevelopment activities.