Post date: Sep 01, 2014 4:52:11 AM
DEQ Approves Permit Changes
Documents just released show that on April 26, 2002, the DEQ modified Pall Life Sciences' NPDES permit, approving the increase in discharge of partially treated purge water from 800 gallons per minute to 1300 gallons per minute.
The DEQ acknowledged that during a dry periods, the Ann Arbor water intake at Barton Pond could show 2 ppb of dioxane... the same level at which the City's Montgomery well was shut down.
The DEQ dismissed all concerns raised by citizens and local governments at the March 18 Public Hearing.
Among the changes requested but not included were:
A reduction in discharge concentrations of 1,4-dioxane proportional to any volume increase, e.g. reduce the monthly average to 6 ppb (= 10 ppb x 800/1300).
Deny discharge rate of 1300 gpm to prevent additional flooding of wetlands and holding ponds in the tributary and to prevent additional erosion in the tributary.
Additional analysis to fulfill the Maximization Requirement and determine how to make the treatment systems treat to less than 3 ppb all of the time instead of just some of the time.
Monitoring of breakdown compounds entering the treatment system as well as exiting the treatment system at the same low level of detect as dioxane (i.e. 1 ppb).
A DEQ loss to groundwater analysis that takes into account the drawdown effects of the purge wells, the recently PLS reported recharge of lower aquifers from the upper most aquifers, and the evidence that water levels in the upper most layers are higher now than before the discharge began.
A requirement to monitor for toluene since it was found in the deep aquifer that will be purged.