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-6 A.3 Fate and Transport Modeling Methods <br /> The RSCA Spreadsheet System contains, a series of fate and transport models for predJtmng CDC <br /> concentrations at the point of exposure (POE) for umiuva exposure pathways, such as air and <br /> groundwater. [ander Tier L relatively simpie analytical models are to be employed for this <br /> dcularwn, representing a minor unaementah effort relative to Ties 1.The spreadsheet modeling <br /> systean is consnsumt with Appendix X.2 of ASTM E-1739,although selected algorithms and default <br /> parameters have been updated to refect advances in evaluation medwc s. <br /> Ilia Id__s_tI=ad sdheahatic shown an Figure Al illustrates the stens mciuded in the RSCA sottware <br /> for ptedt=ng transport of aatuzzzunanrs from the source zone to the POE for air and groundwater <br /> exposure pathways.(Please note that POE attenuation factors and surrace water exposure pathways <br /> ane not i neiuded m the software at this time- See Volume 1.Figure 10)Each element m Figure Al <br /> represents a step-speafic attenuation factor, corresponding to either a cross-media manster factor <br /> (CM)or a lateral transport factor(L-F).The effective NAF value for each COC on each pathway is <br /> then calculated as the andhmenc product of the various attenuation fadars occurring along the flow <br /> path from source to receptor. These steady-state NAF values are thm used for calculation of <br /> baseline asks and bade-taI-,,non of Ste-Soe=&Target Leven(Sgr sL as discussed m Se=on AZ <br /> above. Please tote that fate and transport modeling is not required for direct wgnsure pathways. <br /> such as sod ingestion or dermal contact. where the source and exposure concentzations are equal <br /> (i.e.- NAF r 1). Analytical models used for conservative estimation of each transport factor are <br /> descabed below <br /> CRCISS MMIA TRANSFER FACTORS <br /> Exposure pathways mvoivmg transport of COCl from one medium to another(e.g,soil-to-=.sod- <br /> to-groundwater) require estimation of the corresponding crow-meaia transter factor. Various <br /> analytical expressions are available for estimamig sod-to-air aolatilaatimi facmrs as a funamon of site <br /> soli characteristics and the physical/chemical properties of volatile organic CDCs. L=dung f;:=rs <br /> for organic and inorganic constituent releases from soil to groundwater ten similarly be esumated <br /> as a function of CDC characterntirs,soil conditions, and annual rainfall infiltration.Cross-media <br /> transfer equations incorporated un the RSCA Spreadsheet System are presented m Figure A3 <br /> beguuung on Page A-11.Detailed discussion of each of diene cross-media factors is provided below <br /> asorr� � <br /> l � k <br /> sur <br /> Vd o � + I I Boal Ah AAW <br /> .. <br /> ir..w m Sart"° r i Flo n° VFW,PW <br /> rsadrti ur Pa.ou.fl. <br /> -------- -------t; ---- ----•-------- - --- - ----- ------ <br /> • r <br /> S+mrttm AemS Ali Adoca J.flF <br /> �aw�al I r r <br /> SdWL <br /> mrrtmo�w � PrpyrtVF�) ,1M2 <br /> -i ---- ------ ---------- --- -- ---- --�---- ------ U12KRUL <br /> 61arr+nwlrs AQ�O Cyavr> u- IJIa�Mr MOWN '� <br /> "emvR� <br /> m.tlwroi m .WWFaint <br /> vary Allr�O �� �^ VF ,oro <br /> �ml �� F'�ttYF.�J avoE <br /> I rww.na..r.,[tan....han.w• �— <br /> 9a1Ci.a�r� Sd <br /> b Lrriwr i.atntr Gt�t>Qrrnt {I 1 4DF%DAF <br /> ��Iowmual Y al a P Gww+o+r� okow"Aaw"M. IoE K vv <br /> inner mum ramp/Ix"I rp=fflon ` FAaOt SCAR I <br /> :Q7vo�- <br /> _•--- ---------------------- - ---• <br /> 14w ma 1 <br /> or -Phowl 0=4 <br /> Gg0UnffW0=r a= <br /> AM4 <br /> �s 4 OYtRwarAuoOn r►oE t <br /> dm <br /> I I Frmme(GAM <br /> a�elrmaCCt <br /> FIGURE A-Z NAF CALCULATION SCHEMATIC zOR 1NC[?.E=DCPOStlAE PATHWAYS IN ABC <br /> WREADSHEEr SYST124 <br /> T T a a 1 G.c�oe�1�aeye4!r Rl�C..dma4 CaneeOw Ae <br />