PG&E Manufactured Gas Plant SQ-VO Merced

PG&E Manufactured Gas Plant SQ-VO Merced

DTSC is proposing to approve a Removal Action Workplan (RAW) pursuant to regulatory authority granted under Chapter 6.8, Division 20, CA Health and Safety Code (H&SC) on the PG&E Manufactured Gas Plant SQ-VO Merced site located at 560 15th Street, Merced, CA in Merced County. The RAW will address impacts to soils, soil gases, and groundwater from previous operations by the former Merced Manufactured Gas Plant. The remedial activities will involve, excavation and disposal at an off-site permitted facility (ies) of approximately 5,800 cubic yards (yds3) or approximately 350 truckloads (approximately 700 round trips) of contaminated soils that are highly impacted by polynuclear aromatic hydrocarbons (PAHs); total petroleum hydrocarbons (TPHs); volatile organic compounds (VOCs), including benzene, toluene, ethylene, and xylenes (BTEXs); and metals. In approximately 300 yds3 or approximately 20 truckloads (approximately 40 round trips) of construction debris (asphalt, concrete, and rubble) will be taken offsite for recycling. In-situ solidification/stabilization (ISS) and monitored natural attenuation (MNA) will also be used to assist in the remediation of chemicals of potential concern (COPCs) in the groundwater. The inaccessible areas (i.e. operations building footprint and gas regulator pad) for remediation will have land use covenants (LUCs) placed upon them. There will be approximately 5,500 yds3 or approximately 330 truckloads (approximately 660 round trips) of clean backfill imported locally within approximately 20 miles of the Site and approximately 20 truckloads (40 round trips) of imported asphalt and concrete materials for repaving the excavated areas. The imported fill will be tested for contaminants in accordance with DTSCs October 2001 Imported Advisory on Clean Fill Material. The construction activities will take an estimated six months to complete. It will be done in phases and expected to start in July 2015 and end in December 2015. Additionally, there will be at least 5 years of groundwater monitoring followed by an assessment on whether additional monitoring is required. During this 5 year period of groundwater monitoring, if testing show the ISS and MNA process is ineffective in reducing the levels of COPCs, then implementation of deep source excavations and off-site disposal at a permitted facility (ies) will occur through a future proposed project and separate CEQA environmental document.

Merced

Merced