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Page 1 of 1 <br /> Vicki McCartney [EH] <br /> From: Nuel Henderson [EH] <br /> Sent: Monday, February 10,2014 4:15 PM <br /> To: 'Larson, Kirk@Waterboards' <br /> Cc: Vicki McCartney[EH];Adrienne Ellsaesser[EH] <br /> Subject: RE: Claim 8502,Weldon Church <br /> Kirk, <br /> I don't think the 16 September 2013 report was necessarily inadequate or ill conceived, but it gives only part of the picture— <br /> the indoor air picture for the days sampled.What the report did not address directly was the crawl space and soil gas data in <br /> regard to the HHRA, and not all of the test conditions were spelled out. My concerns are as follows: <br /> 1) This report does not address the health risk of the contaminants in the crawl space,where benzene was present at <br /> 310 ug/m3 during the last sampling event;the crawl space risk was addressed in a previous report as noted in the <br /> EHD response letter to the recent RSR. <br /> 2) The samples, both indoor and crawl space,were collected while the venting mitigation system was in operation, <br /> presumably removing impacted air from the crawl space;these samples therefore are not representative of natural <br /> conditions that will prevail if the site is closed. <br /> 3) The prevailing wind direction in Tracy is from the NW;the ambient air samples were all collected on the lee side of <br /> the residence and in the general area of the former UST; I'm not sure but what the data may actually represent the <br /> outdoor air exposure for this site and not necessarily the ambient air coming onto the site. <br /> 4) The HHRA was for an adult;the case for a child was not reported. <br /> As I noted in our letter to you, I am very concerned about the effects on the residents on this property in the future if we close <br /> this site at this time.The groundwater numbers look great, but the vapor issue bothers me. In our county,Tracy seems to be <br /> the area of potential vapor problems, maybe because of the shallow depth to water in the area, commonly less than 10 feet. <br /> Dealing with the vapor issue is still new to us and as you know,this site presents significant hurdles for remediation. <br /> At this time I would recommend conducting some additional soil investigation near and beneath the residence to identify <br /> where the primary vapor generating soil is, perhaps by using the absorbent sampling devises,then come up with a <br /> remediation plan. Currently the vapor problem is being mitigated, not remediated. Data requirements at this time include such <br /> data as is necessary to identify the location of the significantly impacted soil and/or groundwater and data that demonstrates <br /> successful remediation of it. I'm not recommending withholding payment,just completing the job. <br /> Thanks for reconsidering this site. <br /> Nuel <br /> From: Larson, Kirk@Waterboards [mailto:Kirk.Larson@waterboards.ca.gov] <br /> Sent: Monday, February 03, 2014 7:57 AM <br /> To: Nuel Henderson [EH] <br /> Subject: Claim 8502,Weldon Church <br /> Nuel: based on your January 10,2014 review of the above,is it your contention the Indoor Air Investigation Report, <br /> September 16,2013 by AGE was inadequate or ill conceived? Should the Fund withhold payment? <br /> What further data do you require to bring this case into a path to closure? Kirk <br /> Engineering Geologist <br /> UST Cleanup Fund,5-Year Review <br /> Phone: 916-341-5663 <br /> Fax: 916-341-5806 <br /> 2/11/2014 <br />