The groundwater remediation project between two buildings near the East Gate entrance, in the area known as Operating Unit 2B, finally got underway after a long delay in startup since last spring.
During set up, one of the 30-foot-long steel electrodes driven into the ground to generate heat struck a plastic sewer line. The sewer line was not on any maps and was undetectable through scanning since it is not iron. Operation of the system began last month after a sewer line bypass was installed, and it will continue through May.
The contamination is from nearby aircraft maintenance operations that resulted in chlorinated solvents, used in cleaning aircraft parts, ending up deep underground in the groundwater. Of the three most common methods for cleaning up groundwater contaminated with solvents and fuels – pumping in neutralizing chemicals, heating up the ground to vaporize and extract the contamination, and bioremediation using microbes – the heat treatment method was chosen for this site because it is the fastest.
It takes weeks for the ground to get to the target temperature of 194 degrees, which is the temperature at which the solvent boils and turns to vapor. Pipes at ground level suck the vapor out of the ground and channel it through a large pipe to the granulated activated carbon filter system.
Other groundwater contamination nearby will be treated by a different method not yet announced. The Alameda Point electrical substation is near the other treatment area, and underground electrical lines leading every which way preclude the use of electrodes to heat the groundwater.
At the October 2011 Alameda Point Restoration Advisory Board (RAB) meeting, the Navy announced that Alameda Point’s monthly RAB meetings would be reduced to quarterly meetings due to budget cutbacks. The Navy said it would welcome a written response from the RAB on how the Navy might continue to carry out its responsibilities for community dialogue during difficult budgetary times.
On February 22, 2012, the RAB sent a letter to the Navy’s Environmental Coordinator for Alameda Point cleanup, Derek Robinson. The letter cited the magnitude of the cleanup effort at Alameda Point – 25 percent of the Navy’s nationwide cleanup budget in Fiscal Year 2011 – as justification for having more than four meetings per year. The RAB offered a reasonable compromise schedule that would add two meetings, bringing the total number of meetings this year to six. The Navy has already indicated that it would continue to host its annual tour of cleanup sites at Alameda Point, which would be in addition to the six meetings being proposed by the RAB.
The RAB also suggested having more than one cleanup site presentation at a meeting in order to make more efficient use of the Navy’s time and money spent on hosting the meetings. In past years, multiple presentations were made at meetings, but this practice ended because of the Navy’s concern that the meetings were too long and community members in attendance would leave before the end.
Right next to the Main Street Ferry Terminal, between the Oakland Estuary and the Dog Park, is the Navy’s cleanup Site 28, also known as the Todd Shipyards site. The contamination at this site — copper and arsenic, and to a lesser extent lead and hydrocarbons — was not the result of Navy activities, even though the Navy owns the property.
Filling in the land with estuary dredge soil contaminated with hydrocarbons from the coal gasification plant that once operated in Oakland was likely responsible for the petroleum-related hydrocarbons in the ground. The Alameda Mole Railroad operated along this route from 1883 until 1939 and was also a possible contributor to the hydrocarbon residue in the soil. Non-Navy shipbuilding and repair between 1941 and the 1980s was responsible for lead, arsenic, and copper contamination.
According to the Navy fact sheet, “The property was leased to various entities for non-Navy shipbuilding and repair between 1941 and 1970. The property was purchased from the Navy in 1970 by the Todd Shipyards Corporation, which used the land as an extension of its adjoining shipyard property until 1983, when the property was then sold to Alameda Gateway Limited. The IR Site 28 portion of the former shipyard reverted to Navy ownership in 1995.”
Paint used on ships
The copper contamination came from paint used on the bottoms of ships. The paint was an anti-fouling paint that served to prevent the growth of barnacles. Copper in the paint acted as the biocide, which is why possible leaching into the estuary is a big concern.
Emerging cleanup technology
Even though the Navy did not cause the contamination, they are responsible for the cleanup, which it performed in 2010. They are also responsible for monitoring the groundwater for 10 years to make sure their methods are permanent. Some of the methods used here were straightforward: Digging up soil and replacing with new soil.
The copper at groundwater level, however, is being dealt with by an emerging technology called metals immobilization. In this process a proprietary non-toxic compound is injected into the ground to bind to the copper and cause it to be absorbed into soil particles, which will prevent it from leaching into the estuary and harming aquatic life. Hence, the term immobilization – the copper is no longer mobile, or able to move. Water and natural microbes in the ground are what activates this immobilization compound. A helpful byproduct of this reaction is that food (carbon) for natural microbes is released, further enhancing the effectiveness of this process.
So-called emerging cleanup technologies are halfway between experimental and mainstream. They have been proven effective in the short term, or in some locations, but have not been in widespread use long enough to be considered 100% effective in every soil type. No one knows for certain if the binding effect will hold, but pilot lab tests were done on soil from Site 28, and the Navy and regulators fully expect it will work. If groundwater monitoring indicates that it’s not working, the Navy will have to come up with another plan since there is no statute of limitations on their responsibility for cleanup.
Designing the workplan for dredging toxic sediment next to Pier 1 at Alameda Point required precision so as not to undermine the stability of the concrete posts supporting the roadway that passes along the pier area. The ground under the water slopes down nearly 40 feet from the cement parking slab adjacent to Wharf Road. Six-foot sediment core samples were obtained during investigations. The varying depths of contamination were charted and used to plot a computer program showing a slope profile that not only would accomplish cleanup, but also maintain the stability of Wharf Road. This means that in some case they are dredging deeper than the contamination.
Dredging toxic mud at the pier area, in what is known as Site 24, got underway in early January 2012. The Maritime Administration had to temporarily vacate this berth. Prior Navy activities east of the pier area, which used solvents, paints, sandblasting materials, and hydrocarbons such as fuels and lubricants, led to contamination when waste products, including pesticides, were disposed of down three storm water drains. The contamination chemicals of concern are cadmium, pesticides, lead, and PCBs. The dredging process requires two methods – vacuuming mud from under the wharf road that is supported by concrete posts, and dredging with a clamshell scoop in the open water.
Vacuuming mud under roadway
The first stage of work, now completed, was vacuuming mud from under the roadway. The specially built dredge pump, equipped with an agitator where the hose contacts the mud, was held in position by a barge-mounted crane that was custom built for this application. The mud went through a large hose, across the roadway, into a drainage basin and into special geotextile tubes that retain the mud.
The water that drained off of the mud, however, was too muddy to immediately send to a filtration system. It was first pumped into a large above ground pool of water in order to dilute it. From there the water was pumped through a series of filtration tanks. The water is being used for dust control and can also be pumped back into the harbor.
Open water precision dredging
The open water dredging is conducted from a barge using a special clamshell scoop that allows virtually no mud to drip out of the jaws when hoisted out of the water. This helps to minimize dispersing fine contaminated sediment in surrounding water, which could necessitate repeat dredging. The scoops of mud are held in the air for about 30 seconds to drain the water before being hoisted over to a dump truck. The trucks are driven a few hundred yards to a special drying pad to dump the mud. As the dredge barge moves out of arms length of the wharf, it will have to deposit the mud in a hopper barge that will then be moved next to the wharf where the mud will be unloaded and put into the dump trucks.
The operator of the dredging rig has a real time computer picture of the contour of the underwater ground surface. The image is aided by positioning sensors on the scoop. This allows the operator to follow precisely the slope design. There is also a floating curtain to keep any disturbed contamination within the work area. At the curtain boom and outside the work area are two floating rafts that detect turbidity, or muddiness, in the water. These rafts send real time measurements to the dredge operator. If the turbidity exceeds a certain limit, the dredging is temporarily halted.
Although the Navy periodically dredged the berthing areas for ship and submarine access when the base was open, their dredging was not able to get close to the wharf or under it, leaving the current legacy of contamination. In the health risk assessment conducted by the Navy, they used the Least Tern as an indicator species since they are the most sensitive birds to forage here, and protecting them would therefore protect all other birds. Fish consumption by humans was also used to determine that remediation was warranted. The investigation process that led to this dredging project began with sediment core samples collected in 2005 and 2006. About 4,000 cubic yards of mud will be dredged.
The past year had some high points and low points in the cleanup process at Alameda Point. Added delays, including a pile-driving surprise, were balanced out by steady progress.
The year saw, among other things, completion of a second Point-wide radiological survey of buildings and structures that identified two building interiors needing radium remediation, a new soil scan for radium on a section of the western runway area, replacement of a storm drain segment next to the Seaplane Lagoon, and preparation of the environmental document for the Berkeley Lab site, which will be useful whether we get the Lab or not.
The contractor preparing to cover the old dump with rocks and soil at the northwest tip of Alameda Point delivered some embarrassing news to the Navy. In the normal course of their duties, work-plan design testing revealed that the shape of part of the contamination did not match the official description. You would think they could just process a work-order change. But the Superfund law requires an additional two-year review process, which will push the completion of this open space opportunity to 2015.
At another cleanup project, the Navy drove over four dozen 30-foot steel electrodes into the ground to heat up the toxins and capture the vapor. But before turning on the electricity, the contractor discovered they had hit a sewer line. The project has since been idle for months awaiting a decision on how to proceed.
The big Seaplane Lagoon dredging project that began in January is certainly one of the most dramatic displays of cleanup. Both the northeast and northwest corners of the lagoon were supposed to have been dredged by April and final soil disposal completed by year’s end. But the contractor failed to meet the deadline and was let go. A new contractor has been testing and removing existing soil, as well as doing extensive set-up over the past two months for the dredging of the northwest corner that will begin in January.
Another dredging project has just begun under the dock area next to the maritime ships. They’re removing mud contaminated from two storm drain lines. That project is on schedule. It’s worth visiting the area to get a glimpse of the elaborate engineering needed to capture and clean water runoff from the mud.
Less dramatic and seldom seen work is always ongoing. Groundwater is monitored at cleanup sites to ensure cleanup goals are being met. One example is the monitoring of the removal of benzene and naphthalene under Shinsei Gardens and vicinity.
Evidence of the Petroleum Program is also seldom seen, other than some white PVC pipes in the ground. But besides the big fuel extraction projects, there is ongoing testing of pipelines and oil/water separators in order to develop a remedial plan.
Finally, and perhaps most important, getting the first, very large, no-cost land conveyance from the Navy next year appears to be on schedule. To help make it happen, the Navy and regulators are planning on modifying cleanup goals by enacting restrictions against future ground-floor residential development near the east entrance to Alameda Point.