potrero view

June 2009

Potrero Power Plant Cleanup Plan Slow to Unfold

By Lori Higa

Pacific Gas and Electric Company Presents Slick Slides to Port Commission, but Little Else

At a regular meeting of the Port of San Francisco last month, in a plush meeting room in the Ferry building, Port commissioners, public relation flacks, and representatives from several regulatory agencies gathered to lean about efforts to deal with environmental toxins – some more than a century old – surrounding the Potrero Power Plant.

The toxins are the legacy of decades of industrial activity.  In 1901, Claus Spreckles built a small manufactured gas plant (MGP) between his sugar refinery – which operated from 1881 to 1951 – and Warm Water Cove’s northern shore. Before the advent of long-distance natural gas pipelines, MGP-produced “town gas” was used for streetlights and industrial processes.  The gas was derived from coal or petroleum in a combustion process that resulted in two types of waste:  (solid) lampblack and viscous (liquid) coal tar.

Coal tar is denser than water.  When released into the environment it moves straight through porous earth, unimpeded by groundwater, until it’s stopped by an impermeable geologic barrier.  Lampblack and coal tar contain poly-aromatic hydrocarbons (PAHs), which are carcinogenic and toxic, and are subject to state and federal cleanup requirements.  

Just north of the sugar refinery site, the Potrero Power Plant sits on property that was purchased by a predecessor to Pacific Gas and Electric Company (PG&E) in the early-1870s to run a larger MGP facility, which closed in 1930, and was dismantled in 1962.  The utility bought Spreckles’ MGP in 1903, and closed its operations in 1915.  An electric generating plant also operated on the property from 1901 to 1979.  That plant was demolished in the 1960s, with pieces of it used as rip-rap.  PG&E operated the Potrero Power Plant until 1999, when it sold it to Southern Energy, now Mirant Corporation.  As part of the sale agreement, PG&E retained liability for cleaning up the toxins at the plant, sugar refinery and electric generating sites.

In addition to a small shoreline strip, the Port owns Pier 70, a 65-acre former industrial site that has been the subject of a master planning effort for the past two years, and which is directly north of and next to the power plant.  MGP-related contamination – including liquid coal tar – affects the shoreline strip, offshore sediments and part of Pier 70, though the toxins don’t appear to be spreading.  According to the Port, “the [PAH’s] chemical characteristics restrict their mobility in the environment.”  

PG&E has been investigating environmental damage and shoreline contamination at the site since the mid-1990s, though it has yet to test for contamination from the original MGP site or under the Potrero Power Plant.   In 2001, the utility signed a voluntary clean-up agreement with the Regional Water Quality Control Board (RWQCB).  Between 2004 and 2008, Port staff submitted several inquiries to the RWQCB identifying unresolved technical issues, resulting from what the agency felt was a lack of objectivity on the part of the utility.

Late last year, PG&E and its consultants sampled offshore sediments.  Based on the resulting data, the utility proposed a site conceptual model and remediation plans to the Port and RWQCB.  A site conceptual model identifies primary contamination sources, shows how chemicals at the original point of release might move in the environment, and identifies pathways to exposure that may harm human health or the environment.  According to Jay Ach, manager of environmental and regulatory affairs in the Port’s maritime division, “It’s a complex site with many different contaminants and different.”  According to RWQCB’s Steven Hill, the site poses no immediate threats to the public.  

In response to the presentations meeting participants seemed cautiously optimistic.  “We want to see a cleanup of hazardous waste as the trail and blue greenways” – the final San Francisco portion of which will pass by the site – “are developed,” said Association of Bay Area Governments’ Maureen Gaffney.  “We are completely supportive of efforts to test for toxins and remediate.”

“Your presentation is excellent and very thorough,” Port Commissioner Kimberly Brandon exclaimed.  “Ever since I joined the commission twelve years ago, I have been hearing about the toxic contamination at the Potrero power plant.  I want to know...what’s the next step...what kind of remediation needs to be done? And as for Warm Water Cove, what will we find there, what needs to be done?”  

“First we will conduct sediment cleanup, which involves dredging and capping the target areas so that nothing gets out that could affect habitat,” PG&E’s director of environmental remediation Tom Wilson said.   Wilson described an interim effort to contain MGP waste from eroding the shoreline by capping and covering the area with rip-rap.  He estimated that this action would take place “by the end of ‘09, depending on permits.”  In addition, Wilson pointed to the possible erection of an upland barrier wall, which would cut off re-contamination of sediment.  As for the cove, Wilson stated “we need to investigate what is there, contact potential responsible parties and ultimately clean it up.”

 “It’s good to see this project moving along,” said Port Commissioner Michael Hardeman.   Meanwhile, local residents and environmentalists continue the long wait for comprehensive cleanup.

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