|Navy Could Shut Down Groundwater Treatment|
Published: Friday, 18 January 2013 04:34
The Navy says that a vapor extraction technique it is using around Shinsei Gardens is no longer necessary. The EPA is not so sure.
The Navy often hears calls to increase its environmental cleanup effort. Now, the community and regulators are hearing a call from the Navy to eliminate one cleanup effort altogether.
Since 2009, several acres of the area north of Bayport have been undergoing groundwater treatment to eliminate hot spots of benzene and naphthalene vapors. The area includes the Shinsei Gardens affordable housing development, former Coast Guard and military housing, the closed Island High School and the Woodstock Child Development Center.
Shinsei Gardens included special building-slab engineering in its design as an extra precaution against vapor intrusion. The Navy now says that its groundwater treatment system is unnecessary and should be shut down.
In a report issued last December, the Navy said the underground vapor extraction system called biosparging is not making the area any safer for human habitation. Biosparging is a form of bioremediation that uses air and oxygen injections to stimulate the growth of naturally occurring bacteria, which break down toxins.
In this case, the contamination is composed of waste material discharged from an Oakland coal gasification plant and an Alameda oil refinery that operated long before the area was filled in. The contamination layer has been dubbed the Marsh Crust.
The Navy's report points to the initial studies in the area that showed no risk from vapors. The only justification for the remediation in the first place was the limited risk of contact with water through non-potable uses, since drinking water will always be supplied by East Bay Municipal Utility District.
Now the Navy says that even non-potable uses are impractical and off the table due to high levels of minerals such as salt. With no way of coming in contact with water containing benzene and naphthalene, the Navy decided to review the data for vapor exposure and concluded there is plenty of evidence to turn off the pumps. The biosparge system was designed to run for eight years in order to reach its cleanup goals.
The Navy's December 2012 technical memorandum is seeking to amend the original cleanup decision — known as the Record of Decision (ROD) — for this cleanup area. They will need the concurrence of the regulatory agencies: the regional Water Board, state Department of Toxic Substances Control (DTSC), and the Environmental Protection Agency (EPA). But the EPA and DTSC are not ready to agree without further testing.
"The Navy's conclusions are not based on current data, site conditions, or investigation methods," the EPA's Chris Lichens said. "Before proceeding with an ROD amendment, the agencies would like the Navy to collect additional data to verify that vapor intrusion would not present a significant risk in the absence of biosparging."
The EPA and DTSC jointly prepared recommendations for additional groundwater, soil vapor, and indoor air sampling and provided those recommendations to the Navy.
According to Lichens, "The Navy has not yet agreed to collect additional data, although we are still discussing it with them."
Alameda resident Richard Bangert writes the online Alameda Point Environmental Report.