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<br /> 51 T.8Y�EtlCpN 7-M-96 ,; 2-32rW, , ,EMCON�,
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<br /> 1141 Lawrence H. Heasleyi Piv�ect P96-0'10.25.�3u1y1it, 1"r?
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<br /> Sun=HWI0 l and Statistical Evaluation of('befidad Data. Residtial�soil data va fust be
<br /> rce►iewrd fai seliddoi of data to be tai luded in thi riskasswnkm Sckcnod data vcn'll thi be`
<br /> asialyzed, k ud'mg 'Getirti;ttiair"of the�vohuz>e of co 'ilie;di
<br /> „ t±esldual COntaTI1>Z>ZitiO ��" Ou of = .
<br /> r n,deLGrirutiatlon of the distnlyution prof7i a of c 6 iia, whether
<br /> else' data are normally or lognon*y distrfli�id), 'fitriceay of de6dtli, the range-of
<br /> eomeactratmns, the arstlanwc: avc rage;,and r the 95 pemera, upper conte` mit (UCL) '
<br /> votr=drahon of the'amhrmicnwn of eai;h chemical. Etthex the 95 p&cdu Uta. or'the
<br /> tri Nh n concelitradon of each dtenucal, whichever Is lower,will be taken as representatIV6 of,
<br /> the aver=Uution in the sail ti=ix. Thi conceiuration will then be used as the uiput
<br /> for fate and harper macieliiig(see exposure assessment below)
<br /> In addition, flus evaluation will idewdfy data gaps needed to adegiia ly complete a Tier 2
<br /> a ment for the site ,(e g., totd petroleum hydrocarbon MPH) conTo.cmon data and
<br /> subsurfi ce soil samples) ,
<br /> Exomure Assessment, A conservative exposure assessment will be umnducted m accords=
<br /> with currant and potential future};tied-use conditions.,The exposure asses�nnent'ander each lard
<br /> use will be compnsed of four basic:elements: (1)kd mt tcatwn of potential exposure pathways,
<br /> (2)'deriti�canon of receptor ezpvsure points (e.g, soil ard aur), (3) est>siu oh of exposure
<br /> point c.onumMagons for each relevant exposure pathway, and (4) esmrration of theoretical
<br /> hmnan exposure levels(i.e.,dosages). 1
<br /> To estunate potential exposure of humus receptors,appropriate fate aril transport modeling will
<br /> be conducted. The pnmary fate and transport pathway that may need to be modeled for
<br /> escalating exposure porn conwwations is unsaturated zone mode ng to assess potecmal
<br /> istipacts from wil to groundwater. Ur=turtted zone mcxielmg will b'kely be performed rising
<br /> the Seasonal Soil Compartment (SI SOU.) model. Costs rdkct review of dvadable data,
<br /> developitierrt of a modeling approach, model runs, optimization of model results, and
<br /> man.
<br /> i •
<br /> Hurnan intake of chemicals will be calculated as the reasonable maxuraun exposure (IZME,
<br /> 95 percent upper bound level)for each receptor of c oncertm and expressed as the amount of the
<br /> substance taken into the body per urut body weight per unit tune, EVmmme levels will be
<br /> estimated based on standard USEPA and Cal-EPA exposure factors for each roceptor of
<br /> con=m All assumed exposure factors(e g.,ac avity patterns,bmavatlabky factors,abwrptton
<br /> factors, cx.) will be dmurnmited. Expo%um lovers of any c;i=wgemc surd non-carcinogerisc
<br /> chanucais will be calculated separately because different exposure assumptions apply. Exposure
<br /> kveb wilt be esunrated for each relevant exposure pathway(soil and dam)tied for each exposure
<br /> route(oral, inhalation,and dmyW c antwt) D.* intakes for the saner route of exposuro will
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