SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Page 1 of 2 Lori Duncan [EH] From: Wynne, Dan [Dan.Wynne@shawgrp.com] Sent: Tuesday, January 10, 2006 11:33 AM To: Lori Duncan [EH] Cc: Harman, Larkin Subject: Don Rodgers: UVIF-CPT, vs Membrane Interface Probe Lori: Per our conversation yesterday, I've assembled some info so that you and Nuel and Margaret can decide if the county will concur with my recommendation for Shaw to substitute the Membrane Interface Probe (MIP), for the Ultraviolet-Induced Fluorimetry-CPT, for use in real-time, downhole evaluation for submerged hydrocarbon at Don Rodgers"Transmission Shop"at 515 West Charter Way. In our work plan I proposed using Gregg Drilling's UVIF-CPT. I proposed it because I am familiar with it, is locally available by a reliable vendor, and I believe that there is a sufficient"concentration"of product at Don Rodgers for it to"find something;" it has a very high detection threshold. The conceptual model here is that there is an poorly-defined residual source mass that is below(not at)the water table at Don's property, probably relict from a leak around WWII, when the water table may have been lower. Because the site is a"silt-plex" (mostly silts, w/smattering of some sandy and maybe clayey units), there is probably a significant mass of sorbed fuel, and as well as one or several zones where the pore space is dually- saturated by both water and fuel product. The fuel product may be immobile because of the low-permeability (fine-grainedness)and the partial saturation; if left unattended it may continue to"bleed"dissolved stuff for many years. An example: recent results of 10,000 ug/L benzene and 45,000 ug/L TPHG in well MW-4R-S. The well is screened 34.5 ft down to 49.5 feet; the top of the well screen is 15 feet below the water table; must be a submerged or really thick source!) My opinion is that the MIP will be a more cost effective tool in trying to quickly find the source mass well enough to plan an cost-effective remedy that will work well on this small, tight-access property. ----------------- Where there is product("free", or immobile partial-saturation)the UVIF-CPT works well. It"reads"the induced fluorimetry every couple of inches downward,just like CPT"reads" skin friction and tip resistance. Gregg's UVIF- CPT was developed by Cone-Tek and Alberta's Peter Robinson, one of the north American CPT"gods"O. Basically it is a poor-man's version of the US Army Corps of Engineers SCAPS, which is quite similar but received extensive DOD sponsorship. Perhaps for this reason there is almost no professional literature"out there"about the UVIF-CPT. The main technical drawbacks with the UVIF-CPT are that it only detects "very high concentration", and that its results are not considered by anybody to be calibrate-able to anything. It is not suitable for chasing or mapping dissolved plumes. Despite this, it absolutely rocked for me on job site where we were sure that there was submerged, immobile gasoline product; the UVIF found three different, thin layers of it. The beauty of it the tool was that we followed "right up"with confirmatory Hydropunch, using the 4-foot screen to "blanket"the UVIF "pick" of product. The MIP uses something really hot downhole, to volatilize contaminants that can be volatilized, the contams cross a membrane, and are "swept" rapidly uphole, within clean tygon tubing, by an "ultrapure carrier gas" like helium. The gas then is run through a GC/MS or some other thing, and pretty decent concentration numbers are generated. Please check out slides 24-27, and 32-35, of the following power point of a use of MIP at a big DOD site: http://clu-in.org/siteopt/proceedings_04/workshops/wed/collins karen,pdf 1/10/2006