Expert Systems for Environmental Applications - ACS Publications

Chapter 14

Remedial Action Priority and Multimedia Environmental Pollutant Assessment Systems J. G. Droppo, Jr. and B. L. Hoopes

Downloaded by UNIV LAVAL on July 11, 2016 | http://pubs.acs.org Publication Date: July 5, 1990 | doi: 10.1021/bk-1990-0431.ch014

Pacific Northwest Laboratory, P.O. Box 999, Richland, WA 99352

The Remedial Action Priority System (RAPS) and Multimedia Environmental Pollutant Assessment System (MEPAS) are different names for an objective exposure pathway evaluation system developed by Pacific Northwest Laboratory to rank chemical and radioactive releases according to their potent i a l human health impacts. Constituent migration and impact are simulated using air, groundwater, overland, surface water, and exposure components based on standard assessment principles and techniques. A shell allows interactive description of the environmental problem to be evaluated, defines required data i n the form of problem-specific worksheets, and allows data input. The assessment methodology uses an extensive constituent database as a consistent source of chemical, physical, and health-related parameters. P a c i f i c Northwest L a b o r a t o r y has d e v e l o p e d h e a l t h impact assessment systems, t h e Remedial A c t i o n P r i o r i t y System (RAPS) and t h e M u l t i m e d i a E n v i r o n m e n t a l P o l l u t a n t Assessment System (MEPAS), f o r the U.S. Department o f Energy (DOE) t o e v a l u a t e t h e r e l a t i v e importance o f e n v i r o n mental problems. RAPS, which was d e v e l o p e d f i r s t , a p p l i e s t o r e l e a s e s from i n a c t i v e waste s i t e s . MEPAS, t h e most r e c e n t v e r s i o n o f t h e s y s tem, a l l o w s c o n s i d e r a t i o n o f r e l e a s e s from b o t h a c t i v e and i n a c t i v e s i t e s . MEPAS d i f f e r s from RAPS m a i n l y i n terms o f t h e t y p e s o f emiss i o n o p t i o n s . A l t h o u g h MEPAS r e t a i n s t h e documented framework o f RAPS (1) , s e v e r a l enhancements have been added t o t h e t r a n s p o r t and exposure components ( 2 ) . The purpose o f t h i s paper i s t o d e s c r i b e MEPAS, a computer-based methodology f o r h e a l t h impact e s t i m a t i o n d e v e l o p e d t o s u p p o r t DOE s i t e prioritization. MEPAS t a k e s a p h y s i c s - b a s e d approach based on c h a r a c t e r i z a t i o n o f exposures r e s u l t i n g from s o u r c e - t o - r e c e p t o r t r a n s p o r t a t DOE s i t e s . I t i s c u r r e n t l y b e i n g used i n DOE's E n v i r o n m e n t a l Survey e f f o r t aimed a t i d e n t i f i c a t i o n and p r i o r i t i z a t i o n o f DOE s i t e s . A P r e l i m i n a r y Summary R e p o r t has been i s s u e d f o r major DOE p r o d u c t i o n s i t e s ( 3 ) , and a F i n a l Summary R e p o r t f o r a l l DOE s i t e s w i l l be a v a i l a b l e i n 1990 . 0097-6156/90/0431-0193$06.00/0 © 1990 American Chemical Society

Hushon; Expert Systems for Environmental Applications ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

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Background Making a comprehensive assessment o f r e l e a s e s o f hazardous m a t e r i a l s to t h e environment c a n be a d i f f i c u l t t a s k . The a c t u a l and/or potent i a l e n v i r o n m e n t a l i s s u e s must be d e f i n e d i n terms o f r e l e a s e s , t r a n s p o r t pathways, and exposure s c e n a r i o s . An assessment approach must then be s e l e c t e d . O p t i o n s i n c l u d e making measurements, s i m u l a t i n g impact w i t h e n v i r o n m e n t a l models, o r employing a c o m b i n a t i o n o f measurements and modeling. The c o m b i n a t i o n approach has t h e advantage o f a l l o w i n g t h e use o f measured v a l u e s t o c a l i b r a t e t h e s p a t i a l and temp o r a l exposure p a t t e r n s g e n e r a t e d w i t h models. C o n s i d e r i n g t h e l a r g e number o f s i t e s and d i v e r s e e n v i r o n m e n t a l i s s u e s i d e n t i f i e d by DOE's E n v i r o n m e n t a l Survey ( 3 ) , DOE chose t h e c o m b i n a t i o n approach and s e l e c t e d a h e a l t h impact m o d e l i n g s t r a t e g y as an o b j e c t i v e b a s i s f o r r a n k i n g e n v i r o n m e n t a l i s s u e s . The g o a l was t o develop a system c o n s i s t e n t w i t h c u r r e n t l y a c c e p t e d assessment methods t h a t would have g e n e r a l a p p l i c a b i l i t y t o t h e wide range o f p o t e n t i a l problems. That system i s MEPAS. The i n d i v i d u a l components o f MEPAS are n o t based on s t a n d a r d , gene r a l l y a c c e p t e d t e c h n i q u e s and methods such as those g i v e n by t h e U.S. E n v i r o n m e n t a l P r o t e c t i o n Agency (EPA) ( 4 ) . R a t h e r , MEPAS i s a f u l l y i n t e g r a t e d p h y s i c s - b a s e d exposure assessment system w i t h a u s e r f r i e n d l y s h e l l d e s i g n e d t o a l l o w a p p l i c a t i o n t o a l a r g e number o f e n v i ronmental i s s u e s . T h i s system has a p p l i c a t i o n s beyond s i t e r a n k i n g i n s i t e - s p e c i f i c r e m e d i a l i n v e s t i g a t i o n and endangerment assessment processes. The MEPAS methodology a l l o w s comprehensive s i t e - s p e c i f i c e v a l u a t i o n s o f a l a r g e number o f problems o c c u r r i n g i n almost any e n v i ronmental s e t t i n g . A l t h o u g h s i m i l a r systems a r e a v a i l a b l e , t h e s e systems a r e l i m i t e d t o t h e l o c a l s i t u a t i o n f o r which t h e system was developed. MEPAS r e p r e s e n t s a composite o f these systems. Although these systems may p r o v i d e b e t t e r c h a r a c t e r i z a t i o n o f c e r t a i n l o c a l p r o c e s s e s , MEPAS p r o v i d e s s u f f i c i e n t s i t e - s p e c i f i c c h a r a c t e r i z a t i o n o f l o c a l c o n d i t i o n s f o r screening environmental issues. MEPAS a l l o w s t h e u s e r t o p r i o r i t i z e hazardous, r a d i o a c t i v e , and mixed-waste s i t e s , based on t h e i r p o t e n t i a l h a z a r d t o p u b l i c h e a l t h . MEPAS i s a p p l i c a b l e t o a wide range o f e n v i r o n m e n t a l management and r e g u l a t o r y c o n d i t i o n s i n c l u d i n g i n a c t i v e s i t e s under t h e Comprehensive E n v i r o n m e n t a l Response, Compensation, and L i a b i l i t y A c t (CERCLA), and a c t i v e s i t e s r e l e a s i n g a i r and water contaminants r e g u l a t e d under o t h e r statutory acts. MEPAS uses s i t e and r e g i o n a l d a t a t o e s t i m a t e l o n g - t e r m p o t e n t i a l h e a l t h i m p a c t s . Average c o n c e n t r a t i o n s r e s u l t i n g i n exposures c a n be d i r e c t l y i n p u t i f they a r e a v a i l a b l e from s i t e m o n i t o r i n g o r m o d e l i n g efforts. These average c o n c e n t r a t i o n s may a l t e r n a t i v e l y be computed u s i n g MEPAS e m i s s i o n and e n v i r o n m e n t a l t r a n s p o r t modules. The p r i n c i p a l o u t p u t i s a p o p u l a t i o n impact i n d e x . Other o u t p u t s i n c l u d e maximum i n d i v i d u a l impact, computed c o n c e n t r a t i o n f i e l d s , and c o n s t i t u e n t pathway s c o r i n g i n f o r m a t i o n . MEPAS uses m a t h e m a t i c a l a l g o r i t h m s and a c o u p l e d pathways a n a l y s i s t o p r e d i c t t h e p o t e n t i a l f o r contaminant m i g r a t i o n from a waste s i t e t o i m p o r t a n t e n v i r o n m e n t a l r e c e p t o r s . Groundwater, o v e r l a n d , s u r f a c e water ( e . g . , r i v e r s and w e t l a n d s ) , and a t m o s p h e r i c pathways a r e considered. U s i n g t h e contaminant t r a n s p o r t p r e d i c t i o n s , computed



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exposure assessments based on d i r e c t contaminant i n g e s t i o n and i n h a l a t i o n and on i n d i r e c t i n t a k e through f o o d p r o d u c t i o n a r e performed f o r the i d e n t i f i e d r e c e p t o r s . The r e l a t i v e h e a l t h impacts a s s o c i a t e d w i t h the s i t e s a r e t h e n c a l c u l a t e d . MEPAS i s n o t an e x p e r t system, because a l l l o g i c p a t h s and i n p u t are f i x e d . However, MEPAS does c o n t a i n elements o f a n e x p e r t knowledge-based system and i s o f i n t e r e s t i n terms o f a framework f o r e v a l u a t i n g e n v i r o n m e n t a l c o n c e r n s . MEPAS i s one o f t h e few c u r r e n t l y a v a i l a b l e f u l l y i n t e g r a t e d systems t h a t a c c o m p l i s h e s t h e i n t e r a c t i v e d e f i n i t i o n , o r g a n i z a t i o n , and assessment o f complex e n v i r o n m e n t a l problems. A l t h o u g h MEPAS a p p l i c a t i o n s a r e o f t e n d a t a i n t e n s i v e , t h e MEPAS documentation p r o v i d e s b o t h a p p l i c a t i o n guidance (5) and d e f i n i t i o n s and s o u r c e s o f i n f o r m a t i o n f o r a l l i n p u t parameters ( 6 ) . When a v a i l a b l e , s i t e - s p e c i f i c d a t a a r e used. A l t e r n a t i v e procedures are prov i d e d f o r e s t i m a t i n g e m i s s i o n , t r a n s p o r t , and exposure parameter v a l u e s f o r s i t e s u s i n g l o c a l , r e g i o n a l , s t a t e , and f e d e r a l i n f o r m a t i o n sources. MEPAS was t e s t e d b y EPA as p a r t o f a model comparison e f f o r t a t Superfund s i t e s ( 4 , 7) . An independent assessment was conducted b y M o r r i s and M e i n h o l d ( 8 ) . T e s t i n g e f f o r t s b y t h e model d e v e l o p e r s a r e documented i n Whelan e t a l . ( 9 , 1 0 ) . A d d i t i o n a l i n f o r m a t i o n on MEPAS a p p l i c a t i o n s i s g i v e n i n Droppo and Buck ( 1 1 ) , H a r t z and Whelan ( 1 2 ) , P o s t o n and Strenge ( 1 3 ) , and Buck and A i k e n ( 1 4 ) . MEPAS Methodology

The MEPAS methodology i s composed o f t h e computer models and t h e supp o r t i n g documentation. The computer components a r e c o m p l e t e l y i n t e g r a t e d i n a s i n g l e u s e r - f r i e n d l y system r e f e r r e d t o as t h e MEPAS s h e l l (15). The a p p l i c a t i o n documentation has been s t r u c t u r e d t o d i r e c t l y c o r r e s p o n d t o t h e o p e r a t i o n o f t h e MEPAS s h e l l ( 5 , 6 ) . The t r a n s p o r t and exposure components have been i n d i v i d u a l l y t e s t e d u s i n g m o n i t o r e d v a l u e s a t DOE s i t e s ( 9 , 1 0 ) . The m i g r a t i o n and f a t e o f contaminants i n each t r a n s p o r t pathway can be s i m u l a t e d u s i n g MEPAS components. The t r a n s p o r t pathways a r e s y s t e m a t i c a l l y i n t e g r a t e d w i t h an exposure assessment component t h a t c o n s i d e r s t h e t y p e , t i m e , and d u r a t i o n o f exposure and t h e l o c a t i o n and s i z e o f t h e p o p u l a t i o n exposed. These v a r i o u s pathways and t h e i r i n t e r a c t i o n s as c o n s i d e r e d by MEPAS a r e d i s c u s s e d i n Droppo e t a l . ( 5 ) . A MEPAS a p p l i c a t i o n uses two s o u r c e s o f d a t a : u s e r i n p u t and cons t i t u e n t database. The u s e r i n p u t s s i t e and r e g i o n a l d a t a t o d e f i n e the n a t u r e o f t h e i s s u e , s o u r c e term, t r a n s p o r t pathway, and exposure s c e n a r i o s . To h e l p ensure c o n s i s t e n c y f o r a l a r g e number o f a p p l i c a t i o n s , a c o n s t i t u e n t database was d e v e l o p e d t h a t c o n t a i n s c h e m i c a l , p h y s i c a l , e n v i r o n m e n t a l , exposure, and t o x i c i t y d a t a f o r each cons t i t u e n t . The c o n s t i t u e n t database used f o r t h e E n v i r o n m e n t a l Survey i s documented b y Strenge and P e t e r s o n ( 1 6 ) . T h i s database c u r r e n t l y has e n t r i e s f o r 397 c o n s t i t u e n t s ; new c o n s t i t u e n t s a r e added as needed.


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One d i f f i c u l t y i n c o n d u c t i n g a l a r g e number o f a p p l i c a t i o n s i s organi z i n g t h e a p p l i c a t i o n s and t h e i r d a t a . A s t a n d a r d i z e d approach i s needed t o a l l o w a c o n s i s t e n t d e f i n i t i o n o f e n v i r o n m e n t a l problems. For example, a f o r m a l c l a s s i f i c a t i o n o f e n v i r o n m e n t a l problems c a n p r o v i d e a framework f o r d a t a o r g a n i z a t i o n . A l t h o u g h t h e approach was l a r g e l y d i c t a t e d by t h e E n v i r o n m e n t a l Survey's c l a s s i f i c a t i o n , t h e MEPAS s t r u c t u r e s h o u l d be a p p l i c a b l e t o e n v i r o n m e n t a l problems i n general. MEPAS c o n t a i n s a s t a n d a r d nomenclature f o r ease o f o r g a n i z i n g environmental a p p l i c a t i o n s . T h i s nomenclature i n c l u d e s t h e terms " f a c i l i t y , " " r a n k i n g u n i t , " and " r e l e a s e u n i t , " w h i c h have t h e f o l l o w i n g s p e c i f i c meanings w i t h i n t h e MEPAS framework. Facility. The term " f a c i l i t y " r e f e r s t o a l o g i c a l g r o u p i n g o f e n v i ronmental problems. T h i s g r o u p i n g was m a i n l y o r g a n i z a t i o n a l ( i . e . , a l l o p e r a t i o n s a t r e g i o n a l f a c i l i t i e s ) i n t h e E n v i r o n m e n t a l Survey, a l t h o u g h g r o u p i n g s by o t h e r g e o g r a p h i c o r p o l i t i c a l d i v i s i o n s c o u l d a l s o be used. The MEPAS f a c i l i t y i s n o r m a l l y e q u i v a l e n t t o t h e term " s i t e " under CERCLA and t o t h e term " f a c i l i t y " under t h e Resource C o n s e r v a t i o n and Recovery A c t (RCRA), w h i c h i n c l u d e s containment d e s i g n s as p a r t o f t h e system under c o n s i d e r a t i o n .

Ranking U n i t . "Ranking u n i t " r e f e r s t o an e n v i r o n m e n t a l i s s u e a t a facility. The d e f i n i t i o n o f a r a n k i n g u n i t i s d e r i v e d d i r e c t l y from i t s use i n t h e E n v i r o n m e n t a l Survey. A r a n k i n g u n i t i s a composite o f s i m i l a r and r e l a t e d e n v i r o n m e n t a l problems l o c a t e d i n a p p r o x i m a t e l y t h e same g e o g r a p h i c l o c a t i o n . There c a n be, and o f t e n a r e , m u l t i p l e ranki n g u n i t s a t each DOE s i t e . Each r a n k i n g u n i t may have m u l t i p l e exposure modes ( e . g . , m u l t i p l e r e l e a s e l o c a t i o n s , d i f f e r e n t r e l e a s e methods, d i f f e r e n t pathways).

R e l e a s e U n i t . "Release u n i t " r e f e r s t o t h e l o c a t i o n i n space and time where a contaminant may be r e l e a s e d i n t o t h e environment. F i g u r e 1 i l l u s t r a t e s t h e r e l a t i o n s h i p between a f a c i l i t y , r a n k i n g u n i t , and r e l e a s e u n i t . The f a c i l i t y has a number o f p o t e n t i a l e n v i ronmental problems: t a n k s , a b u i l d i n g v e n t , and a l a n d f i l l . The t a n k s are shown as a r a n k i n g u n i t ( e n v i r o n m e n t a l i s s u e ) a s s o c i a t e d w i t h t h e facility. The l e a k from a s i n g l e tank i l l u s t r a t e s a r e l e a s e u n i t subd i v i s i o n o f the ranking u n i t . These terms a r e s u f f i c i e n t f o r a p p l i c a t i o n s up t o t h e p o i n t o f r e l e a s e o f a hazardous m a t e r i a l i n t o t h e environment. F o r each release, a "scenario" i s defined to describe both the environmental t r a n s p o r t and t h e exposure r o u t e s . The terms " s i t e " and "waste s i t e " were n o t g i v e n s p e c i f i c meani n g s because t h e s e terms a r e used t o r e f e r t o s e v e r a l e n v i r o n m e n t a l problem a t t r i b u t e s . A l s o , t h e d e s i g n a t i o n o f a waste s i t e r e f e r s o n l y to i n a c t i v e s i t e s , whereby MEPAS i s d e s i g n e d t o a p p l y t o e n v i r o n m e n t a l r e l e a s e s from b o t h a c t i v e o p e r a t i o n s and i n a c t i v e waste s i t e s .


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MEPAS S h e l l The MEPAS s h e l l was developed t o a l l o w e x p e d i e n t a p p l i c a t i o n o f MEPAS to a l a r g e number o f e n v i r o n m e n t a l i s s u e s . The MEPAS s h e l l h e l p s t h e u s e r make s p e c i f i c a p p l i c a t i o n s and p r o v i d e s a n o v e r a l l database s t r u c t u r e f o r making a l a r g e number o f a p p l i c a t i o n s a l l o w s t h e u s e r t o i n t e r a c t i v e l y d e f i n e a problem f o r a n a l y s i s o f t h e problem

and approach

c r e a t e s p r o b l e m - s p e c i f i c worksheets


automates d a t a e n t r y , e r r o r c h e c k i n g , and documentation a l l o w s t h e u s e r t o make t r a n s p o r t and exposure

computations

p r o v i d e s easy access and m a n i p u l a t i o n o f s i t e d a t a and f i l e s f o r a s s e s s i n g p o t e n t i a l h e a l t h impacts from e n v i r o n m e n t a l r e l e a s e s o f hazardous m a t e r i a l s . The t r a n s p o r t and exposure components ( 1 , 2) c a n be r u n independ e n t l y from the MEPAS s h e l l . However, the MEPAS s h e l l g r e a t l y improves the ease and a c c u r a c y o f a n a l y z i n g a l a r g e number o f e n v i r o n m e n t a l problems by automating f i l e c r e a t i o n s , making range checks on i n p u t s , and o r g a n i z i n g r e q u i r e d d a t a . The MEPAS s h e l l p r o v i d e s u s e r - f r i e n d l y o p e r a t i o n o f problem d e f i n i t i o n , d a t a e n t r y , f i l e c r e a t i o n , and e x e c u t i o n o f e n v i r o n m e n t a l s i m u l a t i o n codes ( 1 7 ) . An IBM PC ( I n t e r n a t i o n a l B u s i n e s s Machines C o r p o r a t i o n , Boca Raton, FL) ( o r 100% c o m p a t i b l e ) w i t h 640K RAM, a 20-Mb h a r d d i s k , and a 132-column p r i n t e r a r e r e q u i r e d . A math cop r o c e s s o r i s n o t r e q u i r e d , b u t i t w i l l g r e a t l y improve model p e r f o r mance. The d a t a c a p t u r e and s t o r a g e programs a r e w r i t t e n i n c o m p i l e d dBASE I I I P l u s (Ashton-Tate, T o r r a n c e , CA). The MEPAS t r a n s p o r t and exposure models a r e w r i t t e n i n FORTRAN, and i n t e r m e d i a t e l i n k a g e p r o grams a r e w r i t t e n i n ' C ' I n s t a l l a t i o n r e q u i r e s a p p r o x i m a t e l y 2 Mb o f d i s k space. T h i s i s a f i l e - b a s e d a p p l i c a t i o n ; a l l d a t a a r e s t o r e d and exchanged between major components b y f i l e i n p u t / o u t p u t . F i g u r e 2 i s t h e main menu o f t h e MEPAS s h e l l . The menu o p t i o n s p r o v i d e access t o t h e f o l l o w i n g components: Constituent Library. The u s e r c a n v i e w t h e p h y s i c a l p r o p e r t i e s of r a d i o n u c l i d e s and c h e m i c a l s used i n t h e MEPAS model.

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U t i l i t y Routines. Various u t i l i t i e s allow the user t o re-index database f i l e s , d e f i n e t h e p r i n t e r , and s e t up a c o l o r m o n i t o r .

C r e a t e /Update/Examine. A l l d a t a e n t r y , e d i t , and r e v i e w f u n c t i o n s take p l a c e under t h i s b r o a d h e a d i n g .


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PACIFIC NORTHWEST LABORATORY Multimedia Environmental Pollutant Assessment System (MEPAS) MAIN MENU - (Version 2.0) U = UtiIity Routines

C = Create/Update/Examine Scenarios and Worksheets

L = Constituent Library 0 = Exit to DOS = Fac iIi ty Ranking Release Scenario

R = Run Reports/Print Results and Worksheets Enter Choice 0

Ironworks Landf i I Is SE Landfill Ranking Unit > Groundwater > Surface Water = CURRENT SELECTIONS =

Copyright (C) 1989 Battelle Memorial Institute.

All Rights Reserved.

FIGURE 2. MEPAS Main Menu


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199

Run/Print Reports/Templates. This s e l e c t i o n enables the user t o s p e c i f y r u n - t i m e p a r a m e t e r s , c r e a t e r u n f i l e s , and invoke t h e MEPAS model. S i m i l a r l y , a l l p r i n t i n g i s done from t h i s menu o p t i o n , i n c l u d i n g g e n e r a t i o n o f i n p u t d a t a l i s t s and i n t e r m e d i a t e and f i n a l r e p o r t s .


For t h e purposes o f t h i s o v e r v i e w , we w i l l d e s c r i b e o n l y t h e major components and f e a t u r e s o f t h e MEPAS s h e l l . C o n s t i t u e n t L i b r a r y . From t h e main menu, t h e u s e r has a v i e w - o n l y window t o t h e c o n s t i t u e n t l i b r a r y . The c o n s t i t u e n t c a n be s e l e c t e d b y e n t e r i n g one o r more c h a r a c t e r s o r by moving t h r o u g h t h e database u s i n g m o t i o n keys such as PgUp o r r i g h t arrow. The v i e w i n c l u d e s a t a b u l a r l i s t o f t h e p r o p e r t i e s o f the c o n s t i t u e n t r e q u i r e d b y t h e exposure model. P r o p e r t i e s o f t h e c o n s t i t u e n t s r e q u i r e d b y t h e model i n c l u d e p h y s i c a l p r o p e r t i e s , such as vapor p r e s s u r e , Henry's l a w c o n s t a n t , and m o l e c u l a r w e i g h t ; exposure d a t a , such as r e f e r e n c e dose, c a n c e r potency, and b i o a c c u m u l a t i o n f a c t o r ; and t y p i c a l v a l u e s f o r s i t e d a t a , such as KOW, KOC, and K^s. F o r t h e DOE a p p l i c a t i o n , t h e u s e r s c o u l d not a l t e r t h e c o n t e n t s o f t h i s l i b r a r y so t h a t t h e same c o n s t i t u e n t l i b r a r y would be used i n a l l a p p l i c a t i o n s . These c o n s t i t u e n t l i b r a r y parameter v a l u e s and t h e i r s o u r c e s a r e documented i n Strenge and Petersen (16). Parameters d e f i n e d b y t h e EPA were used as a p r i m a r y source o f i n f o r m a t i o n . D e f i n i n g a Case f o r A n a l y s i s . The s c r e e n t h a t appears a f t e r s e l e c t i o n o f t h e Create/Update/Examine o p t i o n from t h e main menu r e f l e c t s t h e s t r u c t u r e f o r d e f i n i t i o n o f cases f o r a n a l y s i s b y MEPAS. D e s c r i p t i v e names a r e g i v e n t o "each s u b d i v i s i o n o f e n v i r o n m e n t a l problems. The names o f c u r r e n t s e l e c t i o n s appear n e x t t o t h e c o r r e s p o n d i n g component, w h i c h appears i n a p a t t e r n on the s c r e e n i l l u s t r a t e d i n F i g u r e 3. Each box can be i n t e r a c t i v e l y s e l e c t e d ( i n sequence from t o p t o bottom) t o a c c e s s d a t a e n t r y s c r e e n s t h a t o c c u r as s u b l e v e l s o f t h e boxes. These d a t a e n t r y s c r e e n s a s s o c i a t e d w i t h each o f t h e s e l e c t i o n boxes shown i n F i g u r e 3 a l l o w t h e p r o g r e s s i v e d e f i n i t i o n o f t h e case t o be analyzed. As n o t e d above, t h e s t r u c t u r e f o r d e f i n i t i o n o f cases f o r a n a l y s i s by MEPAS s t a r t s w i t h the f a c i l i t y . A f a c i l i t y may have one o r more e n v i r o n m e n t a l i s s u e s ( r a n k i n g u n i t s ) . The e n v i r o n m e n t a l i s s u e s may be composed o f one o r more r e l e a s e s i n t o t h e environment ( r e l e a s e u n i t s ) . These r e l e a s e s may then t r a v e l and impact p e o p l e i n one o r more ways ( s c e n a r i o s ) . To s t a r t t h e sequence o f d e f i n i n g e n v i r o n m e n t a l problems, the u s e r p o s i t i o n s the s e l e c t o r b a r on t h e FACILITY d e s i g n a t i o n , and p r e s s e s RETURN. I n t h e n e x t s c r e e n s t h a t appear, t h e u s e r e i t h e r d e f i n e s a new f a c i l i t y o r s e l e c t s a p r e v i o u s l y d e f i n e d f a c i l i t y . F o r a new f a c i l i t y , a d u p l i c a t e o f t h e e n t i r e database f o r a p r e v i o u s l y d e f i n e d f a c i l i t y may be used. The d e f i n i t i o n o f a f a c i l i t y i n v o l v e s f a c i l i t y l o c a t i o n d e s c r i p t o r s and r e l e v a n t u s e r s and r e v i e w e r s names. The n e x t s t e p i s t o g i v e r a n k i n g u n i t names t o t h e e n v i r o n m e n t a l problems t o be a n a l y z e d . A f t e r r e t u r n i n g from t h e FACILITY s e l e c t i o n , the s h e l l w i l l , by d e f a u l t , move t h e s e l e c t o r b a r t o t h e RANKING UNIT p o s i t i o n t o r e i n f o r c e t h e concept o f l o g i c a l p r o g r e s s i o n t h a t i s implemented throughout t h e s h e l l . The u s e r can e i t h e r s e l e c t from a l i s t



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of r a n k i n g u n i t s a l r e a d y p r e p a r e d f o r the p a r e n t f a c i l i t y o r add one. A new r a n k i n g u n i t can be based on d u p l i c a t i o n o f d a t a f o r a p r e v i o u s l y defined ranking unit. A data entry screen w i t h l o c a t i o n i n f o r m a t i o n needs t o be completed f o r each new r a n k i n g u n i t . To d e f i n e a r e l e a s e u n i t , the u s e r p o s i t i o n s the s e l e c t o r b a r on RELEASE UNIT and p r e s s e s RETURN. A f t e r r e t u r n i n g from the RANKING UNIT s e l e c t i o n , the s h e l l w i l l , by d e f a u l t , move the s e l e c t o r b a r to t h i s p o s i t i o n . As w i t h the r a n k i n g u n i t , the u s e r can e i t h e r s e l e c t from a l i s t o f r a n k i n g u n i t s a l r e a d y p r e p a r e d f o r the p a r e n t f a c i l i t y o r add one. The d a t a e n t r y s c r e e n s f o r a r e l e a s e u n i t i n c l u d e the i d e n t i f i c a t i o n of c o n s t i t u e n t s of concern. The u s e r s e l e c t s a maximum o f 20 c o n s t i t u e n t s from the c o n s t i t u e n t c h e m i c a l p r o p e r t i e s database, i n c l u d i n g b o t h p a r e n t and decay p r o d u c t s . F a s t i n t e r a c t i v e cons t i t u e n t s e a r c h o p t i o n s are p r o v i d e d w i t h s i m p l e o n - s c r e e n c o n s t i t u ent s e l e c t i o n . To h e l p i n t h i s s e l e c t i o n p r o c e s s , a l t e r n a t i v e cons t i t u e n t names are l i s t e d . I n a d d i t i o n , the u s e r can a c c e s s s c r e e n s l i s t i n g the p r o p e r t i e s f o r each c o n s t i t u e n t . The SCENARIO s e l e c t i o n a c t i v a t e s s c r e e n s f o r d e f i n i t i o n o f the t r a n s p o r t and exposure s c e n a r i o t o be used i n e v a l u a t i o n o f the e n v i ronmental problems. The u s e r can s e l e c t from a l i s t o f s c e n a r i o s a l r e a d y s e t up f o r the c u r r e n t r a n k i n g u n i t o r choose t o add one. To add a s c e n a r i o , the u s e r must choose the pathway t h a t most c l o s e l y r e p r e s e n t s the a c t u a l problem and then s e l e c t those waste u n i t cons t i t u e n t s t h a t are t r a n s p o r t e d by t h i s p a r t i c u l a r pathway; add o r s e l e c t r e c e p t o r s ; and match the r e c e p t o r s w i t h exposure r o u t e s , such as i n g e s t i o n , b a t h i n g , and d i r e c t c o n t a c t . A f t e r f a c i l i t y , r a n k i n g u n i t , r e l e a s e u n i t , and s c e n a r i o d a t a i n p u t are complete, the u s e r has d e f i n e d the major elements o f the e n v i r o n m e n t a l problem t o be a n a l y z e d . The u s e r can t h e n p r o c e e d t o screens f o r e n t r y o f d a t a needed t o e v a l u a t e t h i s problem. P r o b l e m - S p e c i f i c Data Templates. The r e q u i r e d p r o b l e m - s p e c i f i c d a t a have been grouped l o g i c a l l y and f o r m a t t e d i n t o d a t a e n t r y t e m p l a t e s . The f i r s t template i s an i n t e r a c t i v e " c o n t r o l o p t i o n " t e m p l a t e used t o d e f i n e the s t r u c t u r e and c o n t e n t s o f the r e m a i n i n g t e m p l a t e s . Once the c o n t r o l o p t i o n t e m p l a t e i s completed, a l i s t i s d i s p l a y e d o f a l l t e m p l a t e s r e q u i r e d f o r the s p e c i f i c problem s e l e c t e d . The s h e l l a t t h i s p o i n t has d e f i n e d the d a t a r e q u i r e d t o a n a l y z e a problem. The u s e r can e i t h e r p r i n t c o p i e s o f b l a n k worksheets o r s t a r t i n t e r a c t i v e l y e n t e r i n g the r e q u i r e d d a t a . Completed worksheets a l s o can be p r i n t e d . I n the E n v i r o n m e n t a l Survey, these d a t a s h e e t s a r e b e i n g used f o r d a t a a c c u r a c y s i t e r e v i e w s and, upon c o m p l e t i o n , as f i l e copies. Parameter d a t a e n t r i e s on these t e m p l a t e s are c o u p l e d w i t h r e f erence number e n t r i e s . I n s i t u a t i o n s where d a t a s o u r c e r e f e r e n c i n g i s r e q u i r e d , the r e f e r e n c e system a l l o w s d e f i n i t i o n o f the s o u r c e f o r each parameter v a l u e . T h i s f e a t u r e i s a c t i v a t e d by a f u n c t i o n key and a l l o w s the u s e r to e n t e r s h o r t r e f e r e n c e s o r f o o t n o t e s . These r e f e r ences can be c r e a t e d , m o d i f i e d , p r i n t e d , and s e a r c h e d by r e f e r e n c e number. An example o f a d a t a template/worksheet i s shown i n F i g u r e 4. In a d d i t i o n to a l i n e d e s c r i p t i o n o f each datum r e q u i r e d , s e v e r a l o t h e r c h a r a c t e r i s t i c s s h o u l d be noted. The f i r s t l i n e t e l l s the u s e r the


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MEPAS MODEL CONFIGURATION SELECTION

FACILITY:

IRONWORKS

RANKING:

LANDFILLS


RB-EASE:

SE LANDFILL

-> SCENARIO:

RU > GW > SW

F I G U R E 3. M E P A S Model Configuration Selection Menu (Create/Update Examine)

2.7 ABSORPTION COEFFICIENTS (kd) - PSZ Facility: IRONWORKS Release: SE LANDFILL Scenario: Release groundwater

Ranking:

02/28/89

11:40:34

LANDFILLS RU010101 SW-T1 (Media = 13)

Page( 1 of 1) a. WA-SUBKD Layer 1 •1/9

(1.3a) Constituent FS-CNAME ANTIMONY COPPER ZINC COMPOUNDS

FIGURE 4.

28

Partially

|[ [ [

6.278E-2] Ref 41.9] Ref 12.7] Ref

Saturated

Zone K

d

Values


201

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E X P E R T SYSTEMS F O R E N V I R O N M E N T A L APPLICATIONS

s e c t i o n number and name o f t h i s t e m p l a t e , which c o r r e s p o n d s t o a sect i o n i n t h e parameter d e f i n i t i o n g u i d e l i n e s . The names o f t h e f a c i l i t y , r a n k i n g u n i t , r e l e a s e u n i t , and s c e n a r i o a r e d i s p l a y e d so the u s e r does n o t need t o remember t h e c u r r e n t c o n f i g u r a t i o n . The p r o c e s s o f d a t a e n t r y t o t h e worksheets i s s u b j e c t t o s e v e r a l c o n t r o l s and g u i d e s d e s i g n e d t o h e l p e l i m i n a t e d a t a i n p u t e r r o r s .


A range f i l t e r i s used f o r v a l u e s t h a t must be w i t h i n a s p e c i f i c range. T y p i c a l v a l u e s a r e p r o v i d e d f o r s e l e c t e d i n p u t parameters t o g i v e the u s e r an i n d i c a t i o n o f v a l u e s a p p r o p r i a t e f o r t h e s e l e c t e d a p p l i c a t i o n . These t y p i c a l v a l u e s a r e n o r m a l l y e n c l o s e d i n b r a c k e t s t o t h e l e f t o f t h e d a t a e n t r y l o c a t i o n f o r t h e parameter as a guide f o r t h e u s e r . F o r example, t h e s h e l l c o n t a i n s a l g o r i t h m s f o r e s t i m a t i n g t y p i c a l v a l u e s based on t h e s i t e - s p e c i f i c d a t a f o r the e q u i l i b r i u m c o e f f i c i e n t s (K^s) . Other t y p i c a l v a l u e s p r o v i d e d f o r t h e u s e r i n c l u d e s o i l s i n f o r m a t i o n from a s o i l c h a r a c t e r i s t i c s database b a s e d on t h e s e l e c t i o n o f s o i l type f o r a s i t e . D e t a i l e d guidance i s p r o v i d e d f o r e v e r y i n p u t parameter i n t h e s u p p o r t i n g documentation ( 6 ) . T h i s guidance i s referenced d i r e c t l y t o t h e t e m p l a t e and i n p u t parameter. The range and u n i t s r e q u i r e d i n the s h e l l templates/worksheets a r e l i s t e d . Valid s i t e - s p e c i f i c measured v a l u e s a r e always t h e f i r s t c h o i c e f o r d e f i n i n g a parameter. I f such d a t a a r e n o t a v a i l a b l e , t h e u s e r i s d i r e c t e d t o d e f i n e s i t e - s p e c i f i c v a l u e s from o t h e r s o u r c e s . The o t h e r s o u r c e s e i t h e r t a k e t h e form o f c h a r t s , graphs, o r maps reproduced i n the guidance, o r o t h e r r e a d i l y a v a i l a b l e i n f o r m a t i o n ( e . g . , r e g i o n a l s o i l maps). I m p o r t i n g c l i m a t o l o g i c a l j o i n t f r e q u e n c y w i n d summaries and p o p u l a t i o n d i s t r i b u t i o n d a t a from s t a n d a r d e x t e r n a l s o u r c e s i s allowed. T h i s saves t h e u s e r from h a v i n g t o i n p u t these l a r g e data matrices. When t h e u s e r e x i t s a worksheet w i t h a q u i t / s a v e , t h e s t a t u s o f t h a t template i s determined, s t o r e d , and d i s p l a y e d i n t h e template selection l i s t . A s c e n a r i o cannot be i n c l u d e d i n an a n a l y s i s i f any o f i t s worksheets a r e i n c o m p l e t e . T r a n s p o r t and Exposure A n a l y s i s . When t h e R u n / P r i n t Reports/ Worksheets o p t i o n i s chosen a t t h e main menu, a submenu i s d i s p l a y e d w i t h s e l e c t i o n o p t i o n s t h a t enable t h e u s e r t o execute t h e MEPAS t r a n s p o r t and exposure codes and p r i n t r e s u l t s from t h e model r u n . The f i r s t s t e p i s t o c r e a t e t h e ASCII i n p u t f i l e s r e q u i r e d by t h e v a r i o u s MEPAS components. A u s e r - d e f i n e d name i s used as a f i l e name to i d e n t i f y t h e p a r t i c u l a r r u n . The c o n f i g u r a t i o n o f a d a t a s e t f o r a r u n c a n be changed as d e s i r e d , b u t w i l l i n c l u d e a f a c i l i t y , r a n k i n g u n i t , one o r more r e l e a s e u n i t s , and up t o 10 s c e n a r i o s p e r r e l e a s e unit. The second s t e p i s t o s e l e c t t h e Run MEPAS Model o p t i o n from t h e R u n / P r i n t Report/Templates menu. The u s e r s e l e c t s t h e d a t a s e t s t o be


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r u n , and t h e model w i l l be i n v o k e d f o r each d a t a s e t s p e c i f i e d . The i n t e r m e d i a t e and f i n a l r e s u l t s a r e w r i t t e n t o ASCII f i l e s . P r i n t i n g Worksheets and A n a l y s i s R e s u l t s . A f t e r t h e s c e n a r i o conf i g u r a t i o n i s complete, r e q u i r e d t e m p l a t e s c a n be p r i n t e d . These p r i n t e d t e m p l a t e s o r worksheets have s e v e r a l f u n c t i o n s . I f printed e a r l y i n t h e c y c l e , they c a n be used as w o r k i n g papers t o a s s i s t i n compiling the data before entering i t i n t o the s h e l l . They c a n be p r i n t e d a t any time t o r e f l e c t t h e c u r r e n t s t a t e o f t h e database, and when t h e a n a l y s i s i s complete, they c a n accompany t h e a n a l y s i s docum e n t a t i o n f o r q u a l i t y assurance and c o n t r o l r e q u i r e m e n t s . The cont e n t s o f t h e r e f e r e n c e l i s t c a n a l s o be p r i n t e d from t h i s o p t i o n . A f t e r t h e a n a l y s i s i s complete, any o f t h e MEPAS model i n p u t and o u t p u t f i l e s f o r t h e a n a l y s i s c a n be p r i n t e d . Normally, the f i n a l summary o u t p u t f i l e w i l l be t h e most u s e f u l . I n t e r m e d i a t e f i l e s a r e p r o v i d e d t o a l l o w t h e u s e r a means o f b e t t e r u n d e r s t a n d i n g t h e d a t a c o n t a i n e d i n t h e summary o u t p u t f i l e . Uses o f t h e MEPAS S h e l l The MEPAS s h e l l p r o v i d e s a framework f o r o r g a n i z i n g t h e p r o c e s s o f c o n d u c t i n g a n a n a l y s i s . B e f o r e development o f t h e s h e l l , much e f f o r t was expended i n c o n d u c t i n g MEPAS a p p l i c a t i o n s w i t h d u p l i c a t i o n o f e f f o r t and o r g a n i z a t i o n , and d a t a e n t r y problems. The s h e l l h e l p s t h e u s e r through t h e complex p r o c e s s o f d e f i n i n g t h e problem, d e f i n i n g what d a t a i n p u t s a r e t o be r e q u i r e d , e n t e r i n g t h e s e d a t a i n p u t s , and r u n n i n g the e n v i r o n m e n t a l s i m u l a t i o n s . The MEPAS s h e l l e n a b l e s f a s t e r , more e f f i c i e n t , and b e t t e r documented a p p l i c a t i o n s . W i t h t h e a d d i t i o n o f t h e MEPAS s h e l l , fewer r e s o u r c e s need t o be d i r e c t e d t o c o m p u t e r - l e v e l d e t a i l s o f model i m p l e mentation. Because t h e s p e c i a l l e v e l o f computer e x p e r t i s e ( i . e . , knowing how t o e n t e r d a t a i n f i l e s t o match a FORTRAN format statement) was e l i m i n a t e d , t h e time f o r t r a i n i n g d a t a e n t r y p e r s o n n e l was g r e a t l y reduced. The MEPAS s h e l l has elements o f a knowledge-based system. The source term, e n v i r o n m e n t a l . t r a n s p o r t , and exposure assessment d a t a e n t r i e s b u i l d a database o f i n f o r m a t i o n t h a t c a n be used t o d e f i n e a d d i t i o n a l e n v i r o n m e n t a l problems. T h i s f e a t u r e , w h i c h was added t o s i m p l i f y e v a l u a t i o n o f s i m i l a r o r r e l a t e d problems, w i l l a l s o be u s e f u l i n the e v a l u a t i o n o f remedial a c t i o n a l t e r n a t i v e s f o r s i t e cleanup u s i n g a b a s e l i n e case. A l s o t h e knowledge base i n t h e c o n s t i t u e n t database grows as MEPAS i s a p p l i e d t o new c o n s t i t u e n t s . Summary The development o f MEPAS f o r a p p l i c a t i o n t o e v a l u a t i o n s o f l a r g e numb e r s o f e n v i r o n m e n t a l i s s u e s based on p o t e n t i a l h e a l t h impacts i s comp l e t e . Whether used t o e v a l u a t e a s i n g l e s i t e w i t h many e n v i r o n m e n t a l impacts, a f a c i l i t y w i t h m u l t i p l e r e l e a s e s , or a c o l l e c t i o n o f f a c i l i t i e s w i t h r e l e a s e s , MEPAS i s an a p p r o p r i a t e t o o l f o r s c r e e n i n g t h e r e l a t i v e importance o f e n v i r o n m e n t a l i s s u e s i n a s c i e n t i f i c and o b j e c t i v e manner.


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Acknowledgments T h i s work was s u p p o r t e d by the U.S. Department o f Energy (DOE) under C o n t r a c t DE-AC06-76RLO 1830. P a c i f i c Northwest L a b o r a t o r y i s o p e r a t e d f o r DOE by B a t t e l l e Memorial I n s t i t u t e .

Literature Cited


1. Whelan, G.; Strenge, D. L.; Droppo, J. G. Jr.; Steelman, B. L. The Remedial Action Priority System (RAPS): Mathematical Formulations; PNL-6200, Pacific Northwest Laboratory, Richland, Washington, 1987. 2. Droppo, J. G. Jr.; Whelan, G.; Buck, J. W.; Strenge, D. L.; Hoopes, B. L.; Walter, M. B. Supplemental Mathematical Formulations: The Multimedia Environmental Pollutant Assessment System (MEPAS); PNL-7201, Pacific Northwest Laboratory, Richland, Washington, 1989. 3. U.S. Department of Energy (DOE). Environmental Survey Preliminary Summary Report of the Defense Production Facilities; DOE/EH-0072, U.S. Department of Energy, Environment, Safety, and Health, Office of Environmental Audit, Washington, D.C., 1988. 4. U.S. Environmental Protection Agency. Analysis of Alternatives to the Superfund Hazard Ranking System; Prepared by Industrial Economics, Incorporated, Cambridge, Massachusetts, 1988. 5. Droppo, J. G. J r . ; Strenge, D. L.; Buck, J. W.; Hoopes. B. L.; Brockhaus, R. D.; Walter, M. B.; Whelan, G. Multimedia Environmental Pollutant Assessment System (MEPAS) Application Guidance Volume 1 - User's Guide: PNL-7216, Pacific Northwest Laboratory, Richland, Washington, 1989. 6.

Droppo, J. G. Jr.; Strenge, D. L.; Buck, J. W.; Hoopes, B. L.; Whelan, G. Multimedia Environmental Pollutant Assessment System (MEPAS) Application Guidance Volume 2 - Guidelines for Evaluating MEPAS Input Parameters; PNL-7216, Pacific Northwest Laboratory, Richland, Washington, 1989.

7. Whelan, G.; Brockhaus, R. D.; Strenge, D. L.; Droppo, J. G. J r . ; Walter, M. B.; Buck, J. W. "Application of the Remedial Action Priority System to Hazardous Waste Sites on the National Priorities List." Superfund '87, Proc. 8th Nat. Conf., 1987, pp 409-413. 8. Morris, S. C.; Meinhold, A. F. Report of Technical Support for the Hazardous Waste Remedial Action Program on Health and Environmental Risks of Inactive Hazardous Waste Sites; BNL-42339, Brookhaven National Laboratory, Long Island, New York, 1988.


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9. Whelan, G.; Strenge, D. L.; Droppo, J. G. J r . "The Remedial Action Priority System (RAPS): Comparison Between Simulated and Observed Environmental Contaminant Levels." Superfund '88, Proc. 9th Nat. Conf., 1988, pp 539-545. 10. Whelan, G.; Droppo, J. G. Jr.; Strenge, D. L.; Walter, M. B.; Buck, J. W. A Demonstration of the Applicability of Implementing the Enhanced Remedial Action Priority System (RAPS) at Hazardous Waste Sites: PNL-7102, Pacific Northwest Laboratory, Richland, Washington, 1989.


11. Droppo, J. G. Jr.; Buck, J. W. "Characterization of the Atmos pheric Pathway at Hazardous Waste Sites." Proc. DOE Model Conf., 1988, pp 1-11. 12. Hartz, Κ. E.; Whelan, G. "MEPAS and RAAS Methodologies as Inte grated into the RI/EA/FS Process." Superfund '88, Proc. 9th Nat. Conf., 1988, pp 295-299. 13. Poston, T. M.; Strenge, D. L. "Estimation of Sport Fish Harvest for Risk and Hazard Assessment of Environmental Contaminants." Proc. 6th Nat. Conf. Haz. Wastes and Haz. Materials, 1989, pp 118-123. 14. Buck, J. W.; Aiken, R. J. "Applications of the Multimedia Environmental Pollutant Assessment System (MEPAS)." Proc. of HAZTECH Int. Conf., 1989, pp 1-10. 15. Buck, J. W.; Hoopes, B. L.; Friedrichs, D. R. Multimedia Environ mental Pollutant Assessment System (MEPAS): Getting Started with MEPAS: PNL-7126, Pacific Northwest Laboratory, Richland, Washington, 1989. 16. Strenge, D. L.; Peterson, S. R. Chemical Data Bases for the Multimedia Environmental Pollutant Assessment System (MEPAS): Version 1: PNL-7145, Pacific Northwest Laboratory, Richland, Washington, 1989. 17. Hoopes, B. L.; Buck, J. W.; Friedrichs, D. L.; Aiken, R. J. The Multimedia Environmental Pollutant Assessment System (MEPAS) UserFriendly Shell: PNL-SA-16284, Pacific Northwest Laboratory, Richland, Washington, 1988. RECEIVED March 8, 1990


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