SD033 - Storm Sewer System B

West Branch of Union Creek



Outfall II after Sediment Cleanup and Site Restoration

Storm Sewer System B (SD033) consists of the west branch of Union Creek, parts of Storm Sewer B, Buildings 810 and 1917, the area around the South Gate, and Outfall II. These facilities are listed as one site, because past activities at these locations may have contributed to the existing contamination in Storm Sewer B. Building 810 is used for aircraft refurbishing activities. A former oil/water separator (OWS), sump and wash-rack that used to discharge to Storm Sewer B have been abandoned, so the facility no longer discharges wastes to the storm sewer. Wastes generated at Building 810 in the past include paints, solvents, lubricants, PCBs, and fuels. Building 1917 was used as an aircraft wash down area. Wastes generated at the building in the past include solvents, soaps, engine oil, hydraulic fluid, and jet fuel. The primary contaminants are trichloroethylene and 1,2-DCE in the groundwater; TPH, PAH, and pesticides in the sediment; and metals and PAHs in the surface soil. These contaminants may be a source of potential human health and ecological risks.

The Travis AFB Groundwater Record of Decision selected Monitored Natural Attenuation (MNA) as the final remedy for groundwater at the site. The MNA monitoring network was established in 2015, and monitoring of the final groundwater remedy is ongoing. 

Based on human health and ecological assessments of the potential risks posed by the soil and sediment contaminants, the NEWIOU Soil, Sediment, and Surface Water Record of Decision selected Land Use Controls for the soil and Excavation for the sediment at this site.

In the summer of 2009, Travis AFB carried out a sediment cleanup action at SD033.  The base excavated the contaminated sediment and transported it to an off-base landfill.  The excavation was conducted to minimize impacts on the existing habitat.  The sediment cleanup action achieved residential cleanup levels for all chemicals of concern, so there are no Land Use Controls in place at the sediment portion of this site. The results of the sediment cleanup action are presented in the SD001/SD033 remedial action completion report.