The Darts are deployed by hand or manual slide hammer into the sediments, anywhere from 1 to 20 feet deep, depending on soil conditions or survey need.
Deployment is now even possible using vibracore technology. Contact Dakota for more details.
Once planted, any PAHs that are attached to sediment soil particles, dissolved in sediment pore water, or exist as a component of non-aqueous phase liquids in the sediments, will migrate into the Dart sampler. They migrate into the Dart sampler because of the PAHs’ high affinity for the SPE material versus its relatively low affinity for water or sediments, generating a considerable concentration gradient.
Typically 24 hours of equilibration time is sufficient, after which the Darts are retrieved, packaged, and sent to Dakota for reading.
Technicians at Dakota run the Darts through an LIF reader which is very similar to UVOST. The result is an LIF log that looks nearly identical to a UVOST log. Similar to UVOST and TarGOST, the LIF response correlates to the total-available-PAH content of the sediment vs. depth. A graphical log in JPG format and high resolution data files are available to the client soon after reading.
Combined with GPS position information, the numerical results are readily visualized with Dakota’s 3D conceptual site model service, allowing the client to visualize the big picture of their sediment PAH contamination at a fraction of the cost of traditional sampling/analysis.