Groundwater-level altitudes and groundwater-flow direction and nature and extent of volatile and semivolatile organic compounds at Petro-Chemical Systems, Inc. (Turtle Bayou), Superfund site, Liberty County, Texas, 2020

The Petro-Chemical Systems, Inc. (Turtle Bayou), Superfund site is 15 miles southeast of Liberty, Texas, in Liberty County. Improper disposal of waste oils led to contamination of soil and groundwater at the site. In cooperation with the U.S. Environmental Protection Agency, the U.S. Geological Survey collected water-quality samples from 11 monitoring wells at the site, in particular the area near well MW-109A (the MW-109 area), in August and September 2020 and compared the water-quality results to the results from previous water-quality sampling events at the site in June 2016 and August 2018 with a focus on benzene concentrations. Contours of groundwater-level altitudes in the MW-109 area indicate that groundwater-flow direction is south-southeasterly in the eastern part and south-southwesterly in the western part.

Of the 51 volatile organic compounds analyzed, 13 were detected in groundwater samples from 1 or more wells. In all but 1 well, MW-109A, concentrations of these compounds were less than 100 micrograms per liter. Benzene is still the principal contaminant of concern, as it persists at concentrations exceeding 53,000 micrograms per liter, although naphthalene also appears to be a contaminant of concern, as it was detected at the greatest concentration of any semivolatile organic compound analyte (1,100 micrograms per liter in the sample from well MW-109A).