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Jerry Ule Page 5 <br /> • February 2.2005 <br /> calculating exposure point concentrations (F-PCs)for current exposure scenarios. <br /> Subsurface solls up to 10 or 12 bgs can become redistributed to the surface during <br /> redevelopment. Therefore, for future exposure scenarios, use the greater of the' <br /> surface soil concentration or the 0 to 10 or 12 ft bgs soil Interval concentration for <br /> each chemical of potential Concern (COPC)as the exposure point concentration <br /> (EPC), consistent with HERD's recommendation In our meeting on January 7, 2003, <br /> 17. Exposure Areas-Consistent with the receptors use of the land. While averaging <br /> over the whole site may be appropriate for outdoor air exposures,for soil exposures <br /> use an area comparable-to a residential lot size when evaluating the residential <br /> scenario, In accordance with DISC and EPA guidance(OTSC, 1999;EPA, 1996; <br /> EPA, 4989). HE=RD recognizes that not ail media were sampled at a density <br /> sufficient to obtain EPCs for residential lot size exposure units. For soil, 9 sampling , <br /> density of a COPC is insufficient for residential backyard area e"veraging(that is less. <br /> than 10 samples per residential lot area), HERD recommends use of a hot spot <br /> approach (EPA, 1989). <br /> SPECIFIC COMMENTS <br /> 1. Many of HERD's comments and agreements reached in meetings(both In person and <br /> via teleconference)have yet to be comploted by the responsible parties. Some of the <br /> key documents and meetings with outstanding fallow-through are as follows. <br /> a. HERD participated In conference calls on January 7,2004,Januaryl2,2004,and <br /> . January 29,2004 to discuss underground pipes discovered In the•undeve4ad ' <br /> poffton of the L&M OU. On Monday,Januaryl2,2004(the day HERD received <br /> the January 9,-2004 'Underground tldtlfy Search ReporP prepared by SPOOR), <br /> HERD provided oral comments including apparent Inconsistencies between photos <br /> and captions or text HERD recommended completion of ate characterization prior <br /> to preparing a health risk assessment in order to avoid the Ukely povslblitty that the <br /> risk assessment will be unacceptable and another risk assessment will need to be <br /> performed utilizing adequate site characterization data. The.responslble parties <br /> were to submit a full underground utUlty report and worts plan for additional <br /> sampling and analyses. In the January 29,2004 conference call it was agreed that <br /> among other topics,*our next teleoonferenm would include a conceptual plan <br /> prepared by the responsible parties for sampling and analyses in the area of the <br /> newly discovered underground pipelines. There has been no fdlow through by the <br /> responsible parties on any or these issues identified over a year ago. <br /> b.' On February 2, 2004 HERD received the Januaty 30, 2004, `Summary of Human <br /> Health Risk Assessment Data Collection, L&"M OU, Stockton, Catrfomie" <br /> prepared by Earth Tech in Sacramento,Caldorhia; on February 5,2004 HERD <br /> participated in a teleconference and provided comments based on a time-Iirpited <br /> review,including the creed for depiction of storm drain, sewer and water lines In <br /> the apartment area, identification of visual contamination, and poteritisl indoor ek <br /> issues. Vinyl chloride,trichloroethylene(TCE),and,tetrachloroethylene (PEE) <br /> were detected do soil gas under apartment buildings at concentrations pnerating <br /> concern for risks from Indoor-air using default assumptions,whereas benzene <br /> • 050202JLtloa - - <br />