EPA reported that Hudson River PCB dredging is “back on target” after high river flow delayed the start of Phase 2 this past spring. What EPA has refused to say, though I repeatedly asked via phone and email, is what effects were exerted on dredging by even faster flows caused by Tropical Storms Irene and Lee, which interrupted dredging during the summer. Indeed, raging currents driven by Irene and Lee caused 500-year flooding, and gouged new channels up to 45 feet deep along the Mohawk River. The storms exerted comparable effects on the Hudson River.
Effects of swift flow include scouring of PCB-laden sediment exposed by dredging to downstream areas; washing away of plantings designed to stabilize the river bottom and reestablish ecosystems; disruption of caps placed over residual PCB sediments; flooding; and deposition of PCB sediment on the shore as 'flood mud'.
A theme popularized in the movie version of Isaac Asimov’s sci-fi book “I, Robot” is: “You must ask the right question.” Regarding the above-mentioned PCB dredging issues, the right questions are the questions that EPA refuses to answer:
--Did tropical storms Irene and Lee wash away caps protecting PCB sediments left in dredge trenches?
--Did the racing river disrupt and transport PCB sediments downstream?
--Did currents wash away vegetation that was planted to stabilize the river bottom, setting back the clock on ecosystem restoration?
--Did the river deposit PCB sediments on shore as 'flood mud'?
After the high-flow event this past spring, EPA sent divers to investigate, and sampled ‘flood mud’. On 31 August, with the river still raging after Tropical Storm Irene, and before arrival o Tropical Storm Lee, these things could not have been done yet. EPA emailed me anyway: “Good news, there were no issues on the project related to Irene.” Based upon no investigation, this had to be EPA policy, not information.
Later, EPA reported that resuspended sediment concentrations had remained "within acceptable guidelines." EPA guidelines, however, are ineffective at measuring PCB mobilization. When storms greatly increase river flow, PCB sediments are scoured and massively diluted. This dilution keeps PCB concentrations in river water (EPA's guideline measurement) "acceptable." With sufficient storm dilution, virtually all of the dredge-disturbed PCB sediment can be driven downstream without contravention of EPA's resuspension guidelines. Thus, invisible to EPA's guidelines, swift flow increases downstream transport of PCB sediments and resulting contamination of river water, ecosystems, and air. EPA's failure to measure these effects with its guidelines, failure to measure the area of newly contaminated river bottom, and silence on these issues, together are ominous.