Middle River Complex: Dark Head Cove Interim Remedial Measures

Sediment Contact Advisory for Dark Head Cove

The Maryland Department of the Environment (MDE) has issued a sediment contact advisory for a portion of Dark Head Cove due to contamination in the sediment. The waterway is near the Martin State Airport site in the Middle River area of Baltimore County. That site includes, in addition to the Maryland Aviation Administration-owned airport, property that had been used to design, manufacture and test aircraft. MDE is overseeing Lockheed Martin Corporation’s environmental assessment and cleanup activities related to the property. In connection with the sediment contact advisory, a floating boom is being installed across a portion of Dark Head Cove to prevent boaters from entering the area and sediment will be removed once the appropriate permits are issued.

What is the issue with the sediments at Dark Head Cove?

Recent near-shore sediment sampling investigations identified polychlorinated biphenyls (PCBs) in the sediment immediately adjacent to Outfall 05 (see Figure 1). As a result of these findings, MDE and the U.S. Environmental Protection Agency (“EPA”) directed Lockheed Martin Corporation (“Lockheed Martin”) to develop and implement an interim remedy to prevent people from being exposed to the PCBs. Lockheed Martin has proposed the installation of a floating boom and silt curtain across a portion of Dark Head Cove. MDE and EPA have agreed to this proposal, pending the acquisition of necessary permits. This barrier will prevent inadvertent exposure by people trying to anchor in this area and will prevent the sediment from migrating into other areas of Dark Head Cove where future remediation will occur.

Figure 1 - Dark Head Cove Sediment Advisory Area Site map showing location of sediment removal area

Why is Lockheed Martin sampling at Dark Head Cove?

Over the past several years, Lockheed Martin has conducted extensive soil, groundwater, sediment and surface water sampling in and around Cow Pens Creek and Dark Head Cove. The purpose of the investigation was to identify the nature and extent of hazardous substances present in the environment that resulted from past historic manufacturing operations. The investigations initially started as part of Lockheed Martin’s efforts to complete its environmental assessmentsfor Maryland’s Voluntary Cleanup Program (VCP). Lockheed Martin also prepared assessment work plans for the U.S. Environmental Protection Agency’s review and approval to address the sediment contamination identified in Dark Head Cove and Cow Pens Creek. As Lockheed Martin analyzed sampling data collected across the Middle River Complex, it proposed additional work plans to conduct further assessment based on the sampling results. 

As a result of these investigations, Lockheed Martin has identified the presence of some heavy metals (principally cadmium), polycyclic aromatic hydrocarbons (PAHs) and PCBs in the sediment of Dark Head Cove. Because the concentrations of these hazardous substances presented a sufficient risk to public health and the environment, the EPA and MDE required Lockheed Martin to develop a remedial action plan to address the contaminated sediments. In response to the agencies, Lockheed Martin prepared and submitted the “Sediment Remedy Design Investigation Work Plan Middle River Complex” and the “Feasibility Study for the Remediation of Sediments Adjacent to Lockheed Martin Middle River Complex” in July 2013. The sample results collected as part of the sediment remedy design investigation identified higher concentrations of PCBs at Outfall 005 than previous studies found. MDE, EPA and Lockheed Martin determined that it is in the best interest of public health and the environment to develop and implement the interim measure described above for this area.

Where did the PCBs come from?

The recent investigation near Outfall 005 was conducted as a result of an onshore soil investigation to better define the extent of PCB contamination in the soil and certain storm drains. The onshore soil investigation was conducted on an area of land bounded to the north, east and south by Chesapeake Park Plaza. The land, known as Block E, once housed a large manufacturing building (Building D) that included a nuclear laboratory, an electrical transformer room and a waste collection area. Lockheed Martin detected elevated PCBs concentrations in the subsurface soil to a depth of twelve feet below the surface of the ground in one area. The first place where high levels of PCBs were found was in the first four feet of soil in the southeastern area of Block E, near a 500,000-gallon water tank used by the Middle River Complex as backup for fighting fires. The second place where PCBs were detected was in the south-central part of where Building D was located, in an area that once housed cleaning, plating, and finishing rooms, an electrical transformer room and an electrical substation outside the building. 

The contamination of Block E with PCBs is likely the result of industrial operations that took place in Building D, from a possible release during demolition of Building D or from use of the Building D basement for storage of PCBs-containing materials.

What are Polychlorinated Biphenyls (PCBs)?

Polychlorinated biphenyls (PCBs) are organic chemicals manufactured for construction materials and electrical products before 1979. Because they have very appealing physical and chemical properties for that use -- they are chemically inert and have a very high flash point – they were used in transformers as insulating fluids and coolants. They have a range of toxicity, depending on the type, product, manufacturer, and differing percentages of chlorine.

The PCBs found in Block E are Aroclor-1254 and Aroclor-1260. No one is exposed at this time, since the public is restricted from access and there is no current industrial worker exposure. Such an exposure would result in unacceptable risk.

What are the potential health impacts of PCBs?

According to the Agency for Toxic Substances and Disease Registry(ATSDR), the most commonly observed health effects in people exposed to large amounts of PCBs are skin conditions such as acne and rashes. Studies in exposed workers have shown changes in blood and urine that may indicate liver damage. PCB exposures in the general population are not likely to result in skin and liver effects. Most of the studies of health effects of PCBs in the general population examined children of mothers who were exposed to PCBs.

Animals that ate food containing large amounts of PCBs for short periods of time had mild liver damage and some died. Animals that ate smaller amounts of PCBs in food over several weeks or months developed various kinds of health effects, including anemia; acne-like skin conditions; and liver, stomach, and thyroid gland injuries. Other effects of PCBs in animals include changes in the immune system, behavioral alterations, and impaired reproduction. PCBs are not known to cause birth defects.

Few studies of workers indicate that PCBs were associated with certain kinds of cancer in humans, such as cancer of the liver and biliary tract. Rats that ate food containing high levels of PCBs for two years developed liver cancer. The Department of Health and Human Services (DHHS) has concluded that PCBs may reasonably be anticipated to be carcinogens. The EPA and the International Agency for Research on Cancer (IARC) have determined that PCBs are probably carcinogenic to humans.

What effect does the presence of PCBs in the sediments in Dark Head Cove have on the safety of eating fish caught in the area?

To protect public health, MDE monitors and evaluates contaminant levels in fish, shellfish and crabs in Maryland waters. The tissues of interest for human health include the edible portions of fish (fillet), crab (crabmeat and "mustard"), and shellfish ("meats"). Such monitoring enables MDE to determine whether the specific contaminant levels in these species are within safe limits for human consumption. Results of such studies are used to issue consumption advisories for recreationally caught fish, shellfish, and crab species in Maryland (see our most recent guidelines). Additionally, since fish, shellfish, and crabs have the potential to accumulate inorganic and organic chemicals in their tissues (even when these materials are not detected in water), monitoring of these species becomes a valuable indicator of environmental pollution in a given waterbody.

MDE issues fish consumption advisories for specific species in specific waterways. Fish consumption guidelines for the Middle River apply to fish caught near Dark Head Cove. Because these advisories consider the fact that fish and crabs regularly travel to and from specific areas within a larger waterway, they are protective for fish caught near Dark Head Cove. These advisories provide guidelines for fish consumption for the general population, women and children for certain species of fish. 

Why is MDE issuing an advisory to avoid contact with the sediments? What does this advisory entail?

Out of an abundance of caution, MDE is issuing an advisory to avoid contacting sediments in this area of Dark Head Cove because of the contamination of the sediments. MDE recommends that people be aware of the potential risks and limit their exposure to the sediments by avoiding anchoring in the area immediately to the southeast of Outfall 005. Figure 2 below shows the area for which MDE is issuing its advisory. 

Figure 2 - Location of Outfall 005Outfall locations in Dark Head Cove

Related links:

Martin State Airport/Middle River Complex land restoration activities

Agency for Toxic Substances and Disease Registry FAQs for PCBs

MDE fish consumption advisory information

MDE fish consumption advisories by species and waterway

Contact Information

For more information please contact the Controlled Hazardous Substance Enforcement Division at 410-537-3493.