After reconstructing the Pall sampling database from the latest monthly summaries and comparing the 2013 quarterly plume maps, it's apparent that Pall's arbitrary distinction between "shallow" and "deep" plumes continues to obscure the northward migration of dioxane in the deeper layers through the Evergreen area... as evidenced by the recent highest ever readings at 465 Dupont and MW-77 (1600 ppb & 2000 ppb, respectively), both of which Pall classifies as being in the shallower D2 aquifer even though their screened elevations match those in deeper Unit E.
Pall's latest plume maps show a couple of new 2000+ ppb bubbles that appeared from nowhere based on the immediately preceding maps. The 2000+ ppb bubble in the MW-77 area on the 3rd quarter 2013 shallow plume map is especially troublesome since it may be an offshoot from the bigger 2000+ ppb contour that was depicted on the deep plume maps up until 2012. You have to go back even farther to 2010 to find 2000+ ppb heading towards Evergreen on the "shallow" plume maps.
Pall also obscures the deeper plume northward migration by having discontinuous plume contours on its "shallow" and "deep" aquifer maps.
I agree with Dan Bicknell that "there is one main glacial till aquifer; not separate aquifer units as concluded by PALL and DEQ". This view is not new... CDM stated as much in its review of the site for the DNR(/DEQ) in 1994: "...the aquifer mapping which is relied upon in forming judgements regarding the movement of ground water might be somewhat artificial."
--Roger--
Roger Rayle
chair, Scio Residents for Safe Water, www.srsw.org
member, Coalition for Action on Remediation of Dioxane (CARD)