From: Pennino, Jim (MPCA)

Sent: Thursday, March 20, 2014 11:02 AM

To: Eddy, Andrew (MPCA)

Subject: Junction Food N Fuel, 3534

I have reviewed the letter, Re: Junction Food N Fuel Hermantown MN, dated January 24, 2014, submitted by Jon Hinkel at MSA.

The letter summarizes the results of additional sub-slab, indoor air, and ambient air sampling in the Casa Latte restaurant building (the former gas station building).  MSA also inventoried chemical substances stored in the restaurant and researched the site and neighborhood history since 1946.  The purpose of these efforts was to determine a source for the occasional chemical vapors found in indoor air samples of the restaurant.  Only cleaning compounds are stored in the building and none of them appeared to contain chlorinated solvents or BETX compounds.  There was no evidence of a former dry cleaner at this site or the immediate neighborhood.  Several sub-slab soil vapor, indoor air, and outdoor ambient air samples were collected since 2006 with the latest sample collected in December, 2013.  Over the years, petroleum compound concentrations in indoor air and sub-slab samples have declined.  Trace levels of several chlorinated compounds, some of which may have been used for vehicle servicing such as parts washing with tetrachloroethene and trichloroethene were detected in the indoor and sub-slab samples, but the sporadic detection of trace levels does not indicate a significant source beneath or near the building.  Freon compounds and other compounds which may be related to refrigeration, ambient air contamination, or lab contaminants were detected sporadically in sub-slab, indoor, and ambient vapor samples are probably not related to the former service station release.  Examination of groundwater quality data collected from monitoring wells and private wells at the site indicated only a very few trace detections of chlorinated compounds which may also be artifacts unrelated to the release at this site.  The indoor vapor samples of petroleum compounds have not exceeded the ISV since 2007 and all other vapor compounds are well below the ISV.  Since public water has been supplied to the homes whose wells were affected or potentially affected by the release at this site, this risk has been mitigated.  Vapor intrusion is also not a risk.  I recommend closure of the file.