Laserfiche WebLink
i <br /> 3. vapor Intrusion Pathway Assessment <br /> December 2018, water Board staff informed Ill that the California <br /> EnvironmentDu meeting Agency (Cal/EP had co menonm awor group to update California- <br /> spec guid In ance intrusionand that pmplatet r - e r <br /> e context of the updated guia Wished. since the guidancehad net <br /> intrusion <br /> finalized as of May 2019, water Board staff requested that new Environmental Screening <br /> Levek (ESdD) developed by the San Francisco Bay Regional water Quality Control Board (San Erandsn <br /> My RegionalWater Quality Control Board, 2019j he used to guide vapor Intrusion assessments in Ripon. <br /> basedSince rals ot on Site-specif c and buBaingspecilic feft0e, exceedance of an ESE Is not an <br /> Indication W ce of an ESL is an indication that further <br /> evaluation of the v occurring.vapor Intrusion is <br /> vapor intrusion pathway may appr p le. <br /> In ve <br /> causes for <br /> or <br /> addition <br /> cal approach <br /> then andf Tier i Con as scope this work Planks designed to be unsistent with the follow g intrusion, toe <br /> technig orygvidance: <br /> • refor the Evnlontion am Mitgmion ofSamodarc Vopor Intrusion to Indoor Air, <br /> Department of Toxic So lateral Central (DTSC), 0VEPA. October 2011 (2011 DM Guidance). <br /> • P Technical Guide for Assessing and Mitigaing the Vapor Worship Pathway tram <br /> Sabsu free Be par to Indoor Air (MINE reduction 920R2-154), United States <br /> Environmental Prot ion Agency USEPA), June 2015. <br /> • Guidance for Screening Level Human Health Rek Assessments, California Department of Toxic <br /> SuhsMnces Control(DTi O)h're of Human and Ecological Ruk All Were Number 4, 14 May <br /> 2019, <br /> BJECTIVE <br /> 3h overall objective a ph Is Imesugetion is to called suit intent Information to assess whether 00C In <br /> sox va tially am rat4 through the vapor <br /> hallow and/« n p intloora q <br /> intrusion pathwayspedaconjaniu�Include: m <br /> Anaseeing attenuation of COfs insoil vapor with distance fromthe water table. <br /> Determine if further evaluation va per mslon is necessarv, while screens g out areas that <br /> vapor <br /> benthil <br /> have ns where theintrusionoal Bar vapor Invasion may exist, identifying snout in buildings for <br /> follow-up evaWatbnc <br /> 3.2 TECHNICAL APPROACH <br /> The technical approach described herein uses multiple lines of evidence to assess the potential vapor <br /> intrusion pathway traingroundwater and son vapor sources to current buildings in the site vicinity, The <br /> I The eard- <br /> StatewatterrReControl Ramat DISC and the Office of Human Health Haw Gainers of resernmentaiiho from Per San Local Bay Regional Water n a::e��t. 0. <br /> 6 aLam <br />