Public Domain Picture: January 15, 2013 - Lower Duwamish River, Sampler Recovery Trip

EPA divers prepare the surface supplied diving system on a cold Seattle morning. Surface supply allows longer working time underwater, as well as plenty of time to decontaminate the diver at the end of the dive. The Region 10 dive unit was asked to help plan and execute the deployment and retrieval of passive sampling devices in the Lower Duwamish River. These devices were collecting bottom data since November of 2012. Passive samplers were collecting information about 'porewater' to help demonstrate whether these devices could be useful in determining the bioavailability of PCBs on the river bottom. EPA defines 'porewater' as: 'the water occupying the spaces between sediment particles ... Contaminants in the interstitial water and in the solid phase are expected to be at thermodynamic equilibrium. This makes interstitial waters useful for assessing contaminant levels and associated toxicity.' We also know that pore water can be related to fish tissue data, so sampling in this manner can be very useful in assessing a site cleanup. EPA divers have deployed a variety of passive samplers to support Superfund work. This technique has the capability of integrating data over a longer period of time--making it more likely that a contaminated groundwater plume discharging to a river like this one will be captured, where other techniques may only produce a snapshot. Lower Duwamish Waterway Superfund Site More about this sampling event To find out more about EPA diving nationally, visit: www.facebook.com/EPAdivers

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Contaminateddiving, Diving, Duwamishriver, Environment, Epa, Epadivers, Seattle, Superfund, Surfacesuppliedair

May 10, 2014