Api publ 4674 1998 scan (american petroleum institute)

~ S T D - A P I / P E T R O PUBL 4b74-ENGL 3198 II 2 O b L b American Petroleum Institute ~~ ASSESSING THE SIGNIFICANCE OF SUBSURFACE CONTAMINANT VAPOR MIGRATION TO ENCLOSED SPACES SITE-SPECIFIC ALTERNATIVES TO GENERIC ESTIMATES `,,-`-`,,`,,`,`,,` - HEALTH AND ENVIRONMENTAL SCIENCES DEPARTMENT PUBLICATION NUMBER 4674 DECEMBER 1998 vadose zone source zone aquifer Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale -b- American Petroleum Institute `,,-`-`,,`,,`,`,,` - American Petroleum Institute Environmental, Health, and Safety Mission and Guiding Principles ~ MISSION PRINCIPLES ~ ~~~~~ The members of the American Petroleum Institute are dedicated to continuous efforts to improve the compatibility of our operations with the environment while economically developing energy resources and supplying high quality products and services to consumers We recognize our responsibility to work with the public, the government, and others to develop and to use natural resources in an environmentally sound manner while protecting the health and safery of our employees and the public To meet these responsibilities, API members pledge to manage our businesses according to thefollowing principles using sound science to prioritize risks and to implement cost-effective management practices: a To recognize and to respond to community concerns about our raw materials, products and operations o To operate our plants and facilities, and to handle our raw materials and products in a manner that protects the environment, and the safety and health of our employees and the public To make safety, health and environmental considerations a priority in our planning, and our development of new products and processes To advise promptly, appropriate officials, employees, customers and the public of information on significant industry-related safety, health and environmental hazards, and to recommend protective measures To counsel customers, transporters and others in the safe use, transportation and disposal of our raw materials, products and waste materials To economically develop and produce natural resources and to conserve those resources by using energy efficiently To extend knowledge by conducting or supporting research on the safety, health and environmental effects of our raw materials, products, processes and waste materials To commit to reduce overall emission and waste generation To work with others to resolve problems created by handling and disposal of hazardous substances from our operations To participate with government and others in creating responsible laws, regulations and standards to safeguard the community, workplace and environment o Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS To promote these principles and practices by sharing experiences and offering assistance to others who produce, handle, use, transport or dispose of similar raw materials, petroleum products and wastes Not for Resale ~ STD.API/PETRO PUBL 4b74-ENGL 1778 2 Ob14588 O Assessing the Significance of Subsurface Contaminant Vapor Migration to Enclosed Spaces `,,-`-`,,`,,`,`,,` - Site-Specific Alternative to Generic Estimates Health and Environmental Sciences Department API PUBLICATION NUMBER 4674 PREPARED UNDER CONTRACT BY: PH.D PAULC JOHNSON, OF CIVIL AND ENVIRONMENTAL ENGINEERING DEPARTMENT ARIZONA STATEUNIVERSITY MARIUSH W KEMBLOWSKI, PH.D UTAHWATERRESEARCH LABORATORY UTAHSTATEUNIVERSITY L JOHNSON, PH.D RICHARD DEPARTMENT OF ENVIRONMENTAL SCIENCE AND ENGINEERING OREGON GRADUATE INSTITUTE DECEMBER 1998 American Petroleum Institute Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ STD.API/PETRO PUBL q b q - E N G L 1778 2 ObLLi589 T B q FOREWORD API PUBLICATIONS NECESSARILY ADDRESS PROBLEMS OF A GENERAL NATURE WITH RESPECT TO PARTICULAR CIRCUMSTANCES, LOCAL, STATE, AND FEDERAL LAWS AND REGULATIONS SHOULD BE REVIEWED API IS NCYT UNDERTAKING TO MEET THE DUTIES OF EMPLOYERS, MANUFACTURERS, OR SUPPLIERS TO WARN AND PROPERLY TRAIN AND EQUIP THEIR EMPLOYEES, AND OTHERS EXPOSED, CONCERNING HEALTH AND SAFETY RISKS AND PRECAUTIONS,NOR UNDERTAKING THEIR OBLIGATIONS UNDER LOCAL, STATE, OR FEDERAL LAWS NOTHING CONTAINED IN ANY API PUBLICATION IS TO BE CONSTRUED AS GRANTING ANY RIGHT, BY IMPLICATION OR OTHERWISE, FOR THE MANUFACTURE, SALE, OR USE OF ANY METHOD, APPARATUS, OR PRODUCT COVERED BY LETTERS PATENT NEITHER SHOULD ANYTHING CONTAINED IN THE PUBLICA'I?ON BE CONSTRUED AS INSURTNG ANYONE AGAINST LIABILITY FOR INFRINGEMENT OF LETTERS PATENT All rights reserved No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permissionfrom the publisher Contact the publisher, API Publishing Services, 1220 L Street, N.W Wáshington, D.C 20005 Copyright O 1998 American Petroleum Institute iii `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ACKNOWLEDGMENTS API STAFF CONTACTS Roger Claff, Health and Environmental Sciences Department Harley Hopkins, Health and Environmental Sciences Department MEMBERS OF THE VAPOR MIGRATION WORKGROUP Phil Bartholomae, BP Oil Company Tim E Buscheck, Chevron Research & Technology Company Chen Chiang, Shell Development Company George Duvall, Shell - Westhollow Lesley Hay Wilson, BP Oil Company Umas Kelmser, Chevron Research & Technology Company Victor Kremesec, Amoco Corporation Tom Moldanato, Exxon Biomedical Sciences, Inc Norm Novick, Mobil Business Resource Corporation R.E Payne, Mobil Oil Corporation Tom Peargin, Chevron Research & Technology Company Joseph P Salanitro, Shell Development Company Adolfo E Silva, Petro-Canada, Inc Curtis Stanley, Shell Development Company Tim Strawn, Exxon Biomedical Sciences, Inc Terry Walden, BP Oil Company Andy Woerner, Exxon Research & Engineering Xiaoping Yang, Amoco Research Center V Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - THE FOLLOWING PEOPLE ARE RECOGNIZED FOR THEIR CONTRIBUTIONS OF TIME AND EXPERTISE DURING THIS STUDY AND IN THE PREPARATION OF THIS REPORT Table of Contents Executive Summary ES- 1.O Introduction 2.0 Current Approaches for the Development of Generic RBSLs 3.0 Key Technical Considerations 4.0 Site-Specific Assessment of the Significance of Vapor Migration to Enclosed Spaces 4.1 4.2 4.3 4.4 4.5 4.6 Direct Measurement of Enclosed-Space Vapor Concentrations 10 Use of Soil Gas Samples Collected Near-Surface or Near Foundation 11 Use of Site-Specific Diffusion Coefficients in Generic RBSL Algorithms 12 Use and Interpretation of Soil Gas Data with Depth 14 Accounting for Attenuation Due to Biodegradation 16 Other Refinements 23 5.0 An Opportunity for the Future 23 6.0 References 27 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - Pape Section List of Figures Figure Schematic of vapor migration scenario and sampling options 34 Figure Johnson and Ettinger (199 1) site-specific vapor attenuation coefficient ~ = ( C i n d ~ r / C ~estimate ~ c e ) as a function of the overall effective vapor-phase porous media diffusion coefficient D.r"ffand distance between the source and foundation LT 35 Estimated time for non-retarded chemicals to reach near steady at the distance L fi-om a source vapor concentrations (T~~/€¿~) For retarded compounds multiply the (zssRv)value by the retardation factor R, defined in Equation (4) 36 Sample presentation using data from a) BP (1997) and b) Fischer et al (1996) 37 Vapor concentration data compared with predictions for one-dixkensional transport through a layered system without degradation, using data fiom a) BP (1997) and b) Fischer et al (1996) 38 Figure Figure Figure Figure Normalized hydrocarbon and oxygen soil gas concentrations in a shallow near-homogeneous setting; data from Ostendorf and Kampbell(l991) Lines show expected concentration profiles in homogeneous settings at near steady conditions for no degradation, and first-order degradation .39 Figure Predicted vapor concentration profiles for a homogeneous system at steady-state with a first-order reaction using Equation (8) 40 Figure Attenuation coefficient predicted by Equation (1O) for the case of a homogeneous medium at steady-state with a first-order degradation reaction .4 Figure Schematic of dominant layer model bio-attenuation scenario .42 Figure 10 Comparison of dominant layer model with data from Fischer et al (1996) 43 Hypothetical plot showing conditions necessary for significant bio-attenuation 44 Figure 11 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - Figure STD.API/PETRO PUBL 4b74-ENGL 1778 0732270 üb14593 Y05 List of Tables Table Refinement options and associated data collection and analysis needs 32 Table Sample use of field data (data from BP 1997) to determine site-specific effective vapor-phase diffusion coefficients 33 Table Inputs used in generating Figure 1O using the dominant layer model `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 33 Executive Summary Vapors in enclosed spaces pose two levels of concern First, enclosed-space vapors may be found at concentrations near those that pose immediate flammability andor health risks These sites warrant immediate attention and response as required by most state and federal regulatory guidance In the second class of sites, concentrations are lower and the concern is for longer term health risks This report focuses exclusively on ỵhis second class of sites, where advection and diffusion occur through a soil layer and into an enclosed space and time is available to adequately address the problem on a site-specific basis The options considered in this document for refining generic vapor migration calculations and assessing the significance of this pathway on a more site-specific basis include: a) direct measurement through sampling of enclosed-space vapors, b) use of near-foundation or near-surface soil gas sampling results, c) use of site-specific homogeneous and layered soil diffusion coefficient estimates in generic algorithms, and d) assessment of bio-attenuation potential Data requirements, data presentation, and data interpretation are discussed and illustrated for each option As discussed in the document, it is envisioned that options (c) and (d) will be used much more often than options (a) and (b) for the assessment of longer term impacts, due to a variety of technical and practical considerations - ES-1 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - The move toward more structured risk-based corrective action (RBCA) approaches has led to an interest in better understanding vapor migration to enclosed spaces The significance of this pathway is currently the subject of intense debate, with many believing that existing non-site-specific risk-based (“generic” or “Tier 1”) screening levels are too conservative As little data are available to justi@ generic approaches, this pathway must be addressed on a more site-specific basis This document provides options for addressing the vapor migration pathway on a more site-specific basis Also, a vision for a simpler site-specific assessment approach is presented and accompanied by a discussion of the steps necessary to progress toward that goal This improved approach considers bio-attenuation, but requires only soil moisture content measurements, or alternatively, in-situ diffusion coefficient measurements, to screen sites `,,-`-`,,`,,`,`,,` - - ES-2 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ ~ ~~ ~ S T D - A P I I P E T R O P U B L 4b74-ENGL 1778 ~ ~ 2 ObLLib25 ô ~ m `,,-`-`,,`,,`,`,,` - Sextro, R 1997 Factors Controlling Entry of Soil Gas Contaminants into Buildings Presented at the Petroleum Environmental Research Forum (PERF) Workshop Brea, CA Febniary6-7 Shah, J.T and H.B Singh 1988 Distribution of Volatile Organic Chemicals in Outdoor and Indoor Air Environmental Science and Technology 22(12): 1381-1386 Smith, J.A., A.K Tisdale, and J.H Cho 1996 Quantification of Natural Vapor Fluxes of Trichloroethylene in the Unsaturated Zone at the Picatinny Arsenal, New Jersey Environmental Science and Technology 30.2243 - 2250 Stout, S 1997 Field Case Studies Chlorinated Hydrocarbon Vapors Presented at the Petroleum Environmental Research Forum (PERF) Workshop Brea, CA February - Unlu, K., M W Kemblowski, J C.Parker, D.K Stevens, P K Chong, and I Kamil, 1992, A screening model for effects of land-disposed wastes on groundwater quality, Journal of Contaminant Hydrology, (1 1), pp 27-49 United States Environmental Protection Agency 1987 Total Exposure Assessment Methodology TEAM Study, Vols - Ofice of Acid Deposition United States Environmental Protection Agency 1992 Assessing Potential Indoor Air Impacts for Superfund Sites Office of Solid Waste and Emergency Response EPA/540/R-95/128 PB96-963502 May United States Environmental Protection Agency 1996 Soil Screening Guidance: Technical Background Document Office of Solid Waste and Emergency Response EPA/540/R-95/128 PB96-963502 May Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS -31 Not for Resale S T D * A P I / P E T R O PUBL 4b74-ENGL 5998 W 0732290 ObL'4b2b 785 I l Table Refinement options and associated data collection and analysis needs Analysis Step Generic RBSL Refinement Relative to Previous Analysis none Indoor Sampling direct measure no prediction NearFoundation and NearSurface Sampling direct measure of current conditions in soil near enclosed-space and estimate of impact to enclosed space site-specific estimates of effective porous media difision coefficients SiteSpecific: Simple Refined Calculation SiteSpecific: Refined site-specific assessment of attenuation due to biodegradation c I SiteSpecific: Refined2 source zone depletion Description calculation of base case RBSLs using generic properties; user should ensure that generic inputs are conservative relative to actual site conditions, soil type and depth to contamination should be known vapor sample collected in enclosed space and compared with regulatory limits near-foundation measurement coupled with simple advective-driven vapor intrusion equation use of algorithms employed in Generic RJ3SL calculation, but input of site-specific effective diffusion coefficient estimate (or value measured in situ), and source zone vapor concentration use of modified screeninglevel algorithms, degradation fitting parameter determined from vertical soil gas profile and soil properties, and possibly effective diffusion coefficient measured in situ same as above, except model refinements account for source depletion Data Needs Relative to Base List of Needs (1) none indoor vapor samples at different times of the year surety of no other sources time since release near-foundation soil gas sample estimate of enclosed-space air exchange rate time since release source zone soil vapor concentration moisture content vs depth effective diffusion coefficients measured in situ (optional) source zone soil vapor concentration moisture content vs depth estimate of time since release soil vapor concentrations with depth, including effective diffusion coefficients measured in situ (optional) same as above, plus source zone dimensions and source mass (1) Base case data needs include: subsurface lithology and depth to contamination - 32 - `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale Table Sample use of field data (data from BP 1997) to determine site-specific effective vapor-phase diffusion coefficients 0, [ft BGS] [m3-H20/ g-soil] I I I 7-10 10-13 siltv sand siltv sand 13-16 sand I I I sand DieffrL [m2/d] 0.19 0.016 0.0 13 0.12 0.20 0.010 0.01 0.10 0.16 0.056 0.10 0.059 0.10 siltv sand 4-7 Dieff [m2/d] ** I I 0.023 0.067 I I 0.025 0.073 0.062 0.068 DT~"/LT = 0.0042 * assuming a bulk soil density of 1.7 g-soil/cm3-soil ** for Dair= 0.09 cm2/s= 0.78 m2/d Table Inputs used in generating Figure 1O using the dominant layer model Layer Thickness [m] 0.3 0.2 0.4 rl O O Deff[m2/d] 0.07 0.02 0.05 Property `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS -33Not for Resale `,,-`-`,,`,,`,`,,` - sewer vadose zone aquifer - data used when assessing near-tem impacts data used when making initial site-specific estimate of longer-term impacts - data used when making estimates accounting for attenuation due to biodegradation - data required for possible future screening approach Figure Schematic of vapor migration scenario and sampling options Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS - 34 Not for Resale ~ ~~ ~~ ~ STD.API/PETRO PUBL 4b7Li-ENGL 1998 II 0732290 ObL4b29 490 I I 1E-O2 attenuation due to mixing with indoor air only (insignificant soil diffusion resistance) 1E-O3 a -1- increase in attenuation due to increase in `,,-`-`,,`,,`,`,,` - 1E-O4 1E-05 - 1E-O6 1E-05 QB 12 exchanges per da] in 100 m3 space Qsoil = L/min Lcnick = 15 cm Dcmck= o m2/d = 0.001 m2/m2 = IlllilI I I I IIU I 1E-04 1E-03 1E-02, 1E-O1 lE+OO DTff/LT[ d d ] Figure Johnson and Ettinger (1991) site-specific vapor attenuation coefficient a'(Cjndoor/Csource) estimate as a function of the overall effective vapor-phase ~ distance ~ between the source and porous media diffusion coefficient D Tand foundation LT - 35 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 1O000 L 1O00 Tss R [dl `,,-`-`,,`,,`,`,,` - 1O0 medium sands (0.03 g-HzO/g-soil) fine sands (0.06 g-H20/g-soil) 10 O 10 15 20 25 30 Distance fi-om Source [m] Figure Estimated time for non-retarded chemicals to reach near steady vapor concentrations (-rsS/Rv)at the distance L fkom a source For retarded compounds multiply the (zss/Rv)value by the retardation factor R, defined in Equation (4) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS - 36 Not for Resale ~ S T D - A P I / P E T R O PUBL 4b7q-ENGL 1996 m 2 UbLclb3L 049 silty sand (O 1 g-H,O/g-soil) sand (0.059 g-H,O/g-soil) 0.2 0.4 0.6 0.8 1.o `,,-`-`,,`,,`,`,,` - 0.0 Normalized Concentration [C/C,,] [g-H,O/g-soil] t -lo2 - isopenme(- 30 ghd m a ) P a - CO2(- 200 gíd m a ) -2.0 0.0 o.2 - O2 (- 300 gíd m a ) 0.4 0.6 0.8 1.o 0.0 0.2 0.4 Normalized Concentration [C/ C,] Figure Sample presentation using data from a) BP (1 997) and b) Fischer et al (1996) -37Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale one-dimensional, steady-state, layered solution w/out degradation using site- silty sand (0.1 g-H,O/g-soil) silty sand (0.12 g-H,O/g-soil) silty sand (O 1O g-H,O/g-soil) sand (0.056 g-H,O/g-soil) - 12 - one-dimensional, steady-state, homogeneous solution w/out degradation (base case for sand (0.059 g-H,O/g-soil) 0.2 0.0 0.4 0.6 1.o 0.8 Normalized Concentration [C/C,,] [g-&O/g-soil] n E same solution, except moisture content increased to 0.15 g-H,O/g-soil in the 0.38 - 0.58 m BGS region Y `,,-`-`,,`,,`,`,,` - a o (3 m *.e W 5o O c.> a I =- i -0.8 -1.2 0.0 one-dimensional, steadystate, layered solution w/out degradation) 0.2 0.4 data 0.6 - 0.8 1.o 0.0 0.2 0.4 Normalized Concentration [C/ ],C Figure Vapor concentration data compared with predictions for one-dimensional transport through a layered system without degradation, using data from a) BP (1997) and b) Fischer et aE (1 996) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS -38Not for Resale S T D - A P I / P E T R O PUBL Lib7Li-ENGL 2 Ob19b33 911 1778 O -oxygen A - total hydrocarbons steady-state 1-Dsolution with uniform properties and no degradation -3 ' ' steady-state i -Dsolution with *" uniform pmperties and firstorder degradation with - - .- - -._ L 0.0 - 0.2 0.4 0.6 0.8 1.o Normalized Concentration [C/ C], Normalized hydrocarbon and oxygen soil gas concentrations in a shallow near-homogeneous setting; data from Ostendorf and Kampbell(l991) Lines show expected concentration profiles in homogeneous settings at near-steady conditions for no degradation, and first-order degradation -39Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - Figure 1.o 0.8 `,,-`-`,,`,,`,`,,` - 0.6 z/L 0.4 0.2 0.0 O o 0.2 0.6 0.4 0.8 1.o c/co Figure Predicted vapor concentration profiles for a homogeneous system at steadystate with a first-order reaction using Equation (8) Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS - 40 Not for Resale ~ STD-API/PETRO P U B L '4b74-ENGL ~ 9 W 2 ObL'4b35 79'4 W 1E-O2 1E-O3 1E-04 a 1E-O5 1E-O6 1E-07 1E-08 1E-O9 1E-05 1E-04 1E-03 1E-02 1E-01 1E+00 Deff/LT[ d d ] Figure Attenuation coefficient predicted by Equation (1O) for the case of a homogeneous medium at steady-state with a first-order degradation reaction -41 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS `,,-`-`,,`,,`,`,,` - Not for Resale STD.API/PETRO Layer Layer Layer P U B L Lib7lr-ENGL 0732290 O b l q b b b 1'798 D3eff L D3eff I c Source e, Concentration Figure Schematic of dominant layer model bio-attenuation scenario Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS c - 42 - `,,-`-`,,`,,`,`,,` - Not for Resale cS0"rce 0.0 diffusion only -0.4 e- first-order - degradation =-* I ,*~ 'e and diffusion a -0.8 a -1.2 difision only dominant layer model predictions q =6 Cr=lx106 -1.6 ' 4D ' ' ' ' ' ' * ' `,,-`-`,,`,,`,`,,` - -2.0 data - - -* e Figure 10 Comparison of dominant layer model with data from Fischer et al (1996) -43 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale 500 400 LClit 300 [cml 200 1O0 O O o 0.05 0.15 0.2 Moisture Content [g-BO/g-soil] `,,-`-`,,`,,`,`,,` - Figure 11 Hypothetical plot showing conditions necessary for significant bioattenuation - 44 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale S T D A P I / P E T R O P U B L 4b74-ENGL m 2 ObLLib37 3 T m 1220 L Street, Northwest Washington, D.C 20005 202-682-8000 h f fp://www.api.org `,,-`-`,,`,,`,`,,` - American Petroleum Institute Order No I46740 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale