In January 2011, petroleum hydrocarbons, known as light non-aqueous phase liquid (LNAPL), were observed on the water in the Dominguez Channel during low tide conditions approximately 400 feet south of the E. Carson Street bridge. The petroleum product appears to enter the channel waters from sediments within the bottom of the channel and from a sub-drain pipe system located in the channel levees. Following the release discovery, the Los Angeles County Department of Public Works (LACDPW), as the channel operator, began performing containment operations using booms and absorbent pads in the waterway.
There are multiple potential sources and preferential pathways within the release area, including numerous petroleum product pipelines. The LARWQCB has issued orders pursuant to the Clean Water Act that require potential responsible parties to complete assessments of the contaminants of concern impacting soil, soil vapor, and groundwater at the Dominguez Channel and determine the extent to which their facilities may have contributed to the release. In an effort to respond to the LARWQCB with a regional approach, Resource Environmental LLC (RELLC) was retained by Shell and Chevron to perform investigations.
Numerous pipelines, owned and/or operated by Shell, Tesoro, Union Oil, and Air Products and Chemicals, are located along the channel within the eastern and western levee roads. One active pipeline operated by Plains All American crosses underneath the channel in the area of the observed release(s). Two former pipelines owned by Shell also crossed underneath the channel in the area of the observed release(s), however, these pipelines were removed in the early 1960’s. In addition, there are four facilities in the vicinity with former or existing underground storage tanks (USTs) and other potential sources of petroleum hydrocarbons, including the former Carson Air Harbor facility at 21611 S. Perry Street (property owned by Shell), a former Texaco Service Station at 1209 E. Carson Street (property owned by Chevron), the 76 Station #6082 at 1025 E. Carson Street (property owned by Chevron), and the former Active RV facility at 1202 E. Carson Street. The channel and these four sites are collectively referred to as the Project Area.
The objectives of RELLC’s investigation of the Dominguez Channel are to:
· Determine the potential source(s) and nature of petroleum seepage in the Dominguez Channel through soil, groundwater, and product testing in the Project Area
· Evaluate soil and groundwater impacts at the Carson Air Harbor site, former Texaco site, 76 site, former Active RV site, and nearby pipelines as potential sources of petroleum seepage into the Dominguez Channel
· Evaluate other area information including other work performed by other Potentially Responsible Parties (PRPs) as it pertains to the petroleum seepage into the Dominguez Channel
· Perform necessary human health risk evaluations associated with soil and groundwater impacts determined during this investigation
· Identify data gaps and follow-up actions as a result of these findings, and
Develop solutions to mitigate petroleum seepage into the Channel. During the course of the petroleum investigation, RELLC is implementing an interim remedial measure that includes residual petroleum removal from a well(s) installed next to the channel and the management of absorbent booms installed along the channel to collect residual petroleum. Additional phases of remedial measures are being developed as information is gathered from the investigation activities.