Tests follow Thea Foss Waterway cleanup
TACOMA – Although a $103 million cleanup of chemical contamination in the Thea Foss Waterway was recently completed, environmental regulators are still trying to decide if traces of pollution in the channel are harmful to living creatures.
Environmental regulators dug up samples from the bottom of the channel this past week to gauge the concentrations of harmful chemicals that exceeded federal and state limits in tests last year.
Some of the mud taken from the waterway will be tested on bottom-dwelling organisms, said Piper Peterson Lee, an Environmental Protection Agency project manager.
Scientists seek information concerning the impact of di(2-ethylhexyl) phthalate, also called DEHP or BEHP. Phthalates are plasticizers and have been used for decades in various consumer products.
Phthalates pollute soil, air and water. And recent government-backed scientific analysis has concluded that small amounts of DEHP probably disrupt human reproduction and healthy child development.
“We already know those phthalates don’t meet the chemical standard. Now we need to know what difference does that make,” she explained.
In the case of the Foss Waterway, the federally approved protocol calls for tests of bristle worms, which burrow in the muck, shrimplike creatures called sand fleas or beach hoppers, and the larvae of certain mussels and sand dollars.
These animals are significant because they exist at the end of the marine food chain as prey to larger aquatic organisms. If they harbor contaminants, the pollutants could be picked up by salmon, threatened orca whales or even people.
In the laboratory, researchers will evaluate what happens to the creatures after being exposed to the Foss sediments for periods of two days, 10 days and 20 days, depending on the organism.
By comparison, the same creatures will be tested in sediment from Carr Inlet, near Gig Harbor. It’s a part of Puget Sound known for its robust populations of bottom-dwelling organisms, said Gary Braun, a biologist who works for Tetra Tech, a consulting firm hired to collect the samples.
Other required tests could include an inventory of organisms found in the Foss sediment. That means a census of worms, mussels, sand dollars, beach hoppers, starfish, sea urchins and other living things. Some of the mud collected last week will be preserved for that purpose, Braun said.