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Page 1 of 2 <br /> Vicki McCartney [EH] <br /> From: Brian Millman [bmillman@advgeoenv.com] <br /> Sent: Thursday, March 22, 2012 3:33 PM <br /> To: Vicki McCartney [EH] <br /> Subject: RE: Vapor Intrusion Mitigation System <br /> Attachments: 1203413.pdf <br /> Vicki, <br /> I am sorry it has taken so long for me to respond, I have been on vacation and then in the field working. <br /> We just received the lab report yesterday for the indoor air samples collected on 12 and 13 March <br /> 2012; the report is attached. The data is mostly favorable. Benzene, toluene, and xylenes were <br /> detected in the living room sample and benzene and toluene were detected in the bathroom sample. <br /> Toluene and xylene were detected below the indoor air ESL's and benzene was detected above the <br /> ESL (but remember the indoor air ESL for benzene is extremely low, 0.084 ug/m3). However, benzene <br /> was detected in the indoor air samples at concentrations just above the concentrations detected in the <br /> ambient air samples. Benzene was detected in ambient air samples at concentrations between 0.45 <br /> and 0.48 ug/m3 and benzene was detected in indoor air samples at concentrations of 0.57 and 0.65 <br /> ug/m3 <br /> Although the benzene concentrations are above the ESL for benzene in indoor air, the cancer risk and <br /> hazard quotient are not exceeded when using the 0.65 ug/m3 concentration in an HHRA; I ran an <br /> HHRA model using 0.65 ug/m3 benzene and the cancer risk was calculated at 4.8*10-7 and the hazard <br /> quotient was calculated at 1.6*10-2. <br /> `siSZ_ X115 iS •C /x/p <br /> Now to answer your questions: 41, <br /> 1. Terra-Petra has a professional engineering license in all the states. See this link for their <br /> qualifications, http://www.terra-r)etra.co-m/civalifications <br /> 2. The only mechanical piece of the system is the fan. The Fantech HP 190SL is specifically <br /> designed for residential use and to run quietly. I have been assured by Terra-Petra that the fan <br /> is very quiet. Additionally, Jeff Skelton is familiar with the type of fan and concurred that it runs <br /> quietly. I have left a message with the manufacturer to try and get the decibel level of the fan. I <br /> will contact you when I hear back from them. <br /> 3. There is no operational manual for the system in general. The mechanical part of the system is <br /> the fan; the only manual I can locate for the fan was included in Appendix B of the work plan <br /> (the installation instruction manual and specification manual). <br /> 4. 1 don't know the exact reason the pipe along the eastern wall of the crawl space does not run the <br /> entire length. I would presume that it was not necessary to produce the desired air exchanges in <br /> order to create the negative pressure in the crawl space. The piping and system was designed <br /> by a competent professional engineer with extensive experience in this field and based on his <br /> calculations this is the design that was prepared. I realize I might not have answered your <br /> question very well. If you would like I can contact Terra-Petra and ask them specifically why that <br /> pipe is shorter than the others. <br /> Let me know if you have any other questions or comments. <br /> Thanks. <br /> Brian W. Millman <br /> 3/23/2012 <br />