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Cleanup Areas and Recent Activities

Former Potrero Power Plant | Site Overview | Cleanup Areas & Recent Activities | FAQ | Archive

To expedite the remediation process, we designated seven separate work areas. This allows us to investigate and remediate each area independently, so that while we conduct work in one area, we do not delay or hold back activities aimed at redevelopment in other areas of the Site.

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We have made significant progress on the environmental investigation and remediation of the site. In 2012, we finished remediation work in two of the seven project areas-the Hoe Down Yard, and the Switchyard and Construction Yard Area. Remediation work in another large area of the site, called Station A is on track to be completed in 2013. That will leave work in only four remaining areas: the Northeast Upland Area and a portion of the Port Property (as shown in the site map above), the Sediments Area, the Tank Farm and the Power Generation facility.

Recent Area-by-Area remediation milestones include:

 

Northeast Area (GenOn and Port of San Francisco Owned)

This area includes the northeastern corner of the Potrero Power Plant property, the shoreline and the southeastern portion of Pier 70 owned by the Port of San Francisco. An extensive soil and groundwater investigation of the area is now complete.

In September 2012, a draft Feasibility Study, which provides an evaluation of the various cleanup options and recommends a preferred approach, was submitted to the Water Board.

Following this, the Water Board held a Public Review process and a Public Meeting on the draft FS in October and responded to the comments received from the public. The Water Board approved the Final FS in December 2012.

Under the cleanup method approved by the Water Board (Solidification with Limited Excavation), we will be using a well-accepted remediation approach, wherein MGP residues at the Power Plant property will be solidified in place using cement and some other additives typically used in the remediation technology. This method will address MGP residues in the area that extend deep below the ground surface and are difficult to excavate. Excavation on the Port property will be used to remove MGP residues at a shallower depth.

The approved cleanup option also includes the installation of a durable cover in both areas where solidified soil is present or additional MGP residues are present in substantially smaller quantities. The durable cover will prevent exposure to the remaining residues. The durable cover involves installing a wear–resistant material (such as paving, buildings, clean soil with vegetation) over the area to contain the soil in place and prevent contact with underground residues.

After implementation of the cleanup, monitoring will be conducted to confirm that groundwater is being protected. Institutional controls will also be used, including a Land Use Covenant (LUC) and a Risk Management Plan (RMP). The RMP will set forth procedures for maintaining the protectiveness of the cleanup efforts, provide safety guidelines for workers to use during future construction and maintenance activities, as well as future site users (based on property owners’ redevelopment plans).

In 2013, activities in the Northeast Area, and the portion of the Port Port Property we will be remediating, will focus on developing information for the remedial design, including conducting a pilot test of the selected remediation technology: in-place solidification of soils. This technology uses cement with various additives to solidify contaminated soils in-place and minimize contaminant mobility. The pilot test will help finalize the exact additive mix and the equipment that will be used for mixing additives into the soil. The in-place solidification of the soil will be both protective of human health and allow for future redevelopment of the property.

Shoreline Cleanup and Stabilization

In 2010, PG&E conducted an interim cleanup action along a portion of the shoreline adjacent to the GenOn Potrero LLC and Pier 70 properties. MGP residues (asphalt-like material) exposed along the shoreline were removed to prevent them from eroding and entering the Bay. With the residues removed, the shoreline was restored and further protected from erosion by placing a specialized fabric layer over the ground surface followed by pieces of stabilizing rock.

 

Switchyard and General Construction Yard Areas (PG&E Owned)

The Switchyard and General Construction Yard remain an integral part of San Francisco's electrical infrastructure. In 2012, the Water Board issued a completion (i.e., No Further Action) letter for environmental work for this portion of the site, indicating that no further remediation work is needed.

In the coming months, PG&E will be working to permanently close three temporary groundwater monitoring wells located in the Switchyard. The wells were used in the past to monitor groundwater quality as part of environmental investigations in the area.

 

Hoe Down Yard (PG&E Owned)

Environmental remediation work for the Hoe Down Yard (a PG&E construction and equipment storage area) has been completed and approved by the Water Board. In 2012, the Water Board issued a completion (i.e., No Further Action) letter for environmental work for this portion of the site, indicating that no further remediation work is needed.

 

Station A Area (GenOn Potrero, LLC Owned)

Site investigations are complete and a Human Health Risk Assessment was approved by the Water Board in February 2012. A draft Risk Management Plan and Land Use Covenant were submitted to GenOn Potrero, LLC and the Water Board in November 2012 and are currently being finalized. Regulatory closure of the area is expected this year (2013).

Power Generation Facility (GenOn Potrero, LLC Owned)

This area includes the recently shut down Unit 3 power plant and immediate surroundings. Some soil and groundwater investigations have already been conducted in this area and additional investigations will take place once the former power plant structure has been removed by the property owner.

Tank Farm Area (GenOn Potrero, LLC Owned)

This area includes three large above-ground fuel tanks formerly used to house fuel oil. Limited soil and groundwater investigations have been conducted in this area. Additional investigations are anticipated once the above ground tanks are removed by the property owner.

Offshore Sediments Investigation Area

This area includes sediments in the San Francisco Bay near the former power plant property. PG&E conducted four phases of sediment investigations including the most recent one conducted in summer 2012.

A Remedial Investigation (RI) Report, which will present the results of our recent investigations in the area, will be prepared this year. When the report is completed and submitted to the Water Board and the Port of San Francisco, we will host a Community Meeting to present the investigation results and answer questions community members may have about the findings.

A Remedial Action Plan, remedial design and permitting will be prepared in 2015 and 2016 and the public will be invited to comment on the feasibility study by the Water Board in advance of its final approval. Remediation of the area is anticipated in 2017.

NOTE: Although the parent corporations, NRG and GenOn, have merged, the wholly owned subsidiaries have not merged or changed names, so GenOn Potrero, LLC remains the owner and operator of the Potrero Generation Stations.