M f t R 3 0 ' 9 0 14:33

116000 Memoria l Drive • S u i t e 200 • H o u s t o n . T e x a s 77079-4006 < ( 7 1 3 ) 496-9600 * Fax ( 7 1 3 ) 486-9698

March 30, 1990

V I A T E L E C O P YMr. Brent Truskowsk iU . S . Environmental Protection Agency1445 Rose AvenueDal la s , T e x a s 75202 W.O. $92-09S u b j e c t : A d d i t i o n a l Responses to Comments and F e a s i b i l i t y S t u d ychanges, A r k w o o d , I n c . S i t eDear Mr. T r u e K o w e k i iO n b e h a l f o f Mass Merchand i s e r s , I n c . ( M M I ) , E R M - S o u t h w e s t , I n c .is by thi s l e t t e r t r a n s m i t t i n g to you one page c on ta in ingresponses to two EPA comments (received March 19, 1990) whichwere not addre s s ed in y e s t e r d a y ' s t r a n s m i t t a l , and the p r o p o s e dchanges to Sec t i on 3 and Volume IX ( T r a a t a b i l i t y S t u d y Repor t) oft h e Revised D r a f t F e a s i b i l i t y S t u d y ( d a t e d March 2 , 1 9 9 0 ) . Page s3-13 and 3-14 are not included, but will f o l l o w shor t ly .P l e a s e review thi s mater ia l t oday and call Ms. J e a n H e a d i e r o fM c K a s e o n or me with any f u r t h e r comments, so they may beaddre s s ed in the F e a s i b i l i t y s t udy document which we w i l l send toyou today.

S i n c e r e l y ,E R M - S O U T H W E S T , I N C .

L e e K . H o l d e r , P . E .L K H / s k d w e rc c: Dan M a o L e m o r o , Roy F. W a s t o n , I n c .Bob Barker, Mass Merchandi s er s , Inc.Robert Rit ch i e , M c K e s s o n C o r p o r a t i o nJ e a n Mevcher, McKes son Corporat ionDinah Darman, M c K e s s o n corporat ionA l l a n Gate s , M i t c h e l l , W i l l i a m s , S e l i g & TuckerRichard F u l l e r , E R M - S o u t h w e s t , inc.

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u 8 ov?ra13- ef f a c t s of site s o i l s . T h e r e f o r e , l eacha t e«aSed, ™?«y**to **a« c a l c u l a t i o n s are' the bestf r o m the s ite ° e8timatlri« concentrations of PCP in l eachate

S S S S S L n l ' ^ p f l r f l? r a^iB n0tE P A d i sagree s with M M I ' 8, "levant or a p p r o p r i a t e ., relevant and a p p r o p r i a t e to the site.«» f»*«»tlon in the RI r e p o r t , the RCRA LDta*„ „. , aPP l i c a b l<> or relevant and a p p r o p r i a t e , changet h e text t o r e f l e c t E P A ' S p o s i t i o n . w»»ng»

th? W a e t i n 9 ' S e c t i o n 3.4.1 has been^11 the P o s i t i o n that RCRA is notland d i B P ° a a l r e s tr i c t ions ( L D R s ) a r enfc and B P P r ° P ^ « t e as guidance in th*a^ernativ*». T h a s e have been s p e c i f i e d inT a b l e 3 - 3 .Comment I A . Paoa a-?i*other s i te contaminants.

th i s s i ta

Add a d i s cu s s i on o f ARARs forE R a9 u l atio« No. 2 contains several s p e c i f i c toxic s8tal}da^s e x i s t , but PCP is the only one of theseJ

a«ooiate<l wi th th« site. The other toxic s ( P C B s ,n' ,2" a nt "Btabo l i t e s , «ndrin, t oxaphenet " ? ° 8 > ? l f a n ' , h e p t a c h l o r , h s xach lorocyc loh sxanea a l»n i u r a' and s i l v e r ) have never been as soc ia t ed withf i o n m e n t 15. Paq» A--}. Pflr f l7Mt?h_l- Add to the f i r s t s entence, " ford e s i g n purpose s" . I n t h e p a r a g r a p h l a b e l e d " A f f a c t e d S o i l s " , t h ei = Z f i v ! h u U l d 3 3 ° W 9 / k 9 > A l B O d e l e t e the las t sentence o f thep a r a g r a p n ,

T h i s has boen done.Paff t t 4~; sieve and wash proceaa*J?V«» both POP and PNAB. Elsewhere in the FS r epor t ,M f e ^ P N A re?oval is ^ a t t r i t i o n . It a l s o s t a t e sH« r*, d e t e c t ed in th* wash water i n d i c a t i n g no actualwashing o f PNAs (*&* t h e T r e a t a b i l i t y S t u d y , page 4-3). Discussthe l e v e l s of the carcinogenic PNAs in the washed sands f r a c t i o n .

The text has been m o d i f i e d to addre s s PNAs and c l a r i f y° ^T *̂.1 d^ng aieva-and-wash. As s tated in thei 4ndi?ator PN^S w«" used to determine the behaviori n c l u d i n g carcinogenic P N A s ( c P N A s ) .of ail

c

-4-

1 9 8 5 ) . On th i s ba s i s , the a p p r o p r i a t e PCP cri terion is 330r o g / k g P C P in s o i l . it is important to note that th i s level ish i g h l y conservative for the f o l l o w i n g reasons! 1) no credit i staksn for l eachate d i l u t i o n in ground water, 2) TCLP test methodsexpose soil to Much acre aggres s ive condi t i on s than w i l l occur innature, and 3) with the ex c ep t i on of the railroad d i t c h , e l evatedPCP concentrations g e n e r a l l y are in s u r f i c i a l s o i l s which have nocontinuous contact with the ground water, but only contacti n f i l t r a t i n g water on a p e r i o d i c basis.A f f e c t e d soil ( n o n - s l u d g e ) concentrations o f PCP are e s t imated tobe 22 f f .g/kg for the ra i l road d i t ch area* T h e s e e s t imated concen-tra t i on s are the geometr i c mean of a n a l y t i c a l va lue s for th i s areaminus the value s for s l u d g e ( e s t i m a t e d as PCP at 100G K g / k g orh i g h e r ) . U s i n g the l inear r e l a t i o n s h i p in F i g u r e 3 - i j f c , the worst-case l ea cha t e would contain l e s s than 0.14 m g / 1 P C P . ghia io veilb c l o w - f e h e - i . Q l - s n g / 1T h i s same a p p r o a c h can be a p p l i e d to an assessment of the mainsite. The main s i te hao two r e p r e s e n t a t i v e PCP concentrat ions:75 m g / k g for the s torage area and 102 m g / k g for the t r o l l e y -traatraent area. U s i n g the r e l a t i o n s h i p in F i g u r e 3-4|{, the worst"case l ea cha t e would contain le s s than 0.28 tag/I for the s toragearea and 0.36 m g / 1 for the t r o l l e y treatment area. As these•leaohate valuco-are w a l l - b e l o w the -a^oi-ag/1 -cr i t er i-on, thenote a t h a e a f e duo f e e l a a o h i n y o fsoil undeg-out tpen- t s i t ef l h e s o f o r e ? — it -ia — e ^ f t e l u d e d that the iremeval — &£- s l u d g e a wouldf c ' ground and t h o f e thin removal -eon ba ' r e l i a b l yon*- visual i d e n t i g i o a f e i o n of f c h e » a f a e t f i a l to be removed i3 .3 S e c t i o n 121 f b! S t a t u t o r y Ob-iectivesS e c t i o n 121 (b) o f CERCLA, as amended by SARA, s ta t e s a s f o l l o w s ;"Remedial act ions in which treatment which p e r m a n e n t l y and s igni-f i c a n t l y reduces the vo lume, t o x i c i t y or m o b i l i t y Q* the hazardoussubstances, p o l l u t a n t s , and contaminants is a p r i n c i p a l e l ement ,are to be p r e f e r r e d over remedial actions not involving such treat-ment," S e c t i o n 1 2 1 ( b ) a l so e x p a n d s th e g o a l s o f remedial actionsto i n c l u d e a p r e f e r e n c e for remedial act ions that u t i l i z e permanents o l u t i o n s and a l t e r n a t i v e treatment t e c h n o l o g i e s or resourcet e c h n o l o g i e s to the maximum extent p r a c t i c a b l e .3 «4 f l e c t i o n 12^.^) S t a t u t o r y O b j e c t i v e . fAfiARalS e c t i o n 121 (d) o f CERCLA, as amended by SARA/ describes the t y p e sof s t a n d a r d s that remedial actions are required to meet. The f u n d -amental s tandard for e v a l u a t i n g remedies under s e c t ion 121 remains" p r o t e c t i o n of huwan h e a l t h and the environment". In a d d i t i o n , the

3-4

3*~ A** • —,

s t a n d a r d s , requirements, criteria or l i m i t a t i o n s under any F e d e r a lenvironmental l a w , or any wore s tringent S t a t e s t a n d a r d s that are" l e g a l l y a p p l i c a b l e or relevant and a p p r o p r i a t e " must be met.Remedial a l t ernat ive s were analyzed to determine p o t e n t i a l a p p l i -cable or relevant and a p p r o p r i a t e r e g u l a t i o n s (ARARs). T a b l e 3-1pre s en t s tha environmental s tandards that were reviewed to deter-mine which had a bearing on remedial action at the site. T a b l e s3-2 and 3-3 present c o n s t i t u e n t - s p e c i f i c and a c t i o n - s p e c i f i cp o t e n t i a l ARARs, r e s p e c t i v e l y , based upon the d i s c u s s i o n s in thef o l l o w i n g sections.3.4.1 A l f o R s f o r S o l i d W a s t e D i s p o s a l

The key p o t e n t i a l ARAR for s o l i d waste d i s p o s a l at CERCLA si t e s i eRCRA and i ta a s s o c ia t ed r e g u l a t i o n s . Key p r o v i s i o n s in c lude:o I d e n t i f i c a t i o n and l i s t i n g o f hazardous waste.o Land d i s p o s a l r e s t r i c t i o n s ( L D R t t ) ,o Minimum t e c h n o l o g y requirements ( M T R s ) .

However , f or the reasons di scus sed be low," a p p l i c a b l e " RCRA is

evant and a p p r o p r a t eTo be a hazardous was te , the s l u d g e s and a f f e c t e d soil at theA r k w o o d , inc. s i t e would have to be a charac t er i s t i c hazardouswaste as d e f i n e d in 40 CFR 261 S u b p a r t C or be l i s t e d as a hazard-*ous waste in 40 CFR 261 S u b p a r t D. A f f e c t e d m a t e r i a l s f r o m theArkwood, Inc. site are not hazardous wastes by characteristic (40C7R 261 S u b p a r t C) based on evaluat ion of the f o u r c h a r a c t e r i s t i c s ,as f o l l o w s :

I g n i t a b i l i t y - The a f f e c t e d m a t e r i a l s are s o l i d s which are notc a p a b l e of caus ing f i r e and, when i g n i t e d , w i l l not burn sov igorou s ly and p e r s i s t e n t l y as to create a hazard. Thea f f e c t e d m a t e r i a l s t h e r e f o r e do not exhibi t the charac t er i s t i co f I g n i t a b i l i t y .C o r r o s i v i t y - The charac t e r i s t i c o f C o r r o a i v i t y i s d e f i n e d f orl i q u i d s , and t h e r e f o r e does not a p p l y to the a f f e c t e d mater ia l sat the site. In a d d i t i o n , a f f e c t e d soil was mixed with waterduring f r e a t a b i l i t y s t u d y soil washing t e s t ing . Tha pH of themixture was a p p r o x i m a t e l y n eu t ra l , as shown in T a b l e 4-3 of theT r e a t a b i l i t y S t u d y Repor t . T h e a f f e c t e d m a t e r i a l s t h e r e f o r edo not exhibit the characteristic of Corroaivity.

p o t e n t i a l C i t a t i o n P o t e n t i a l A o o h c a b i I i l y

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S i t e a c l i v n i e to ( ( - n l e s c i 1 0 w a s t eTain <j«i I anS u f f i c el a n d

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As the s i t e did not treat wastewater, the KOOl d e f i n i t i o n dees nota p p l y to the site* S u p p o r t i n g th i s , EPA guidance s ta t e s that "Alls l u d g e s at a wood preserving f a c i l i t y would not q u a l i f y ne c e s sar i lyas KOOl wastes .. * For e xampl e wood d r i p p i n g s that contain creosoteor p e n t a c h l o r o p h e n o l are not K Q O l . " f s y o e r f u n d c o m p l i a n c a with theRCRA Land D i s p o s a l Res tr i c t i ons . U . S . EPA, August 3 , 1988 D r a f t ,p. 4-20. T h i s document was provided to E R M - S o u t h w e s t , I n c . by Ms,Ruth I s r a e l i , E P A ' s f i r s t Remedial Proj e c t O f f i c e r f o r this s i te ,as guidance to be f o l l o w e d . )To summarize, RCRA is not a p p l i c a b l e at the A r k w o o d , I n c . s itebecause no hazardous waste is present. In a d d i t i o n , as di scus sedb e l ow , I S M i S i i i R C H A - i a neither relevant nor a p p r o p r i a t e f or theA r k w o o d , I n c . site.A c c o r d i n g to EPA gu idanc e , for j$g$$ f c e R f c to be relevant anda p p r o p r i a t e , the material must be " s u f f i c i e n t l y s imilar" to al i s t e d hazardous waste ( I b i 4 , p . 1-1), U . S . E P A , Augus t 3 , 1988D r a f t , p* 1-1. A f f e c t e d mat er ia l s at the s i te would have to bep h y s i c a l l y and c h e m i c a l l y s i m i l a r , i n c l u d i n g the waste matr ix , toa l i s t e d hazardous waste such that the cons iderat ions used ine s t a b l i s h i n g the LDRs a n d / o r MTRs for that l i s t e d waste area p p r o p r i a t e for the risk posed by the waste.The concept o f " s u f f i c i e n t l y s imilar" i s f o u n d only in d r a f t EPAguidance , and not in any s t a tu t e or r egula t ion. As recognized byEPA guidance , the a f f e c t e d soil matrix i s s u b s t a n t i a l l y d i f f e r e n tf r o m the o r i g i n a l , "pure" waste, such that cons iderat ions appro-p r i a t e for the "pure" waste are not a p p r o p r i a t e for a f f e c t e d so i l .In re sponse , the EPA has created the concept s of "soil and debriswaste (SDW)» and "non-soil and debris waste (NSDW)» ( Z f e i d , p . 1-1 ) . T h e a f f e c t e d s o i l s a t t h e Arkwood , I n c . cite c l e a r l y q u a l i f yas sow. The m a t e r i a l s r e f e r r e d to as " s ludge s " in thi s reportal so q u a l i f y as "soil and debri s waste", in that they are theresult o f P C P - c o n t a i n i n g f l u i d s i n t e r m i n g l i n g with soil .A c c o r d i n g to EPA gu idanc e , "It is important to note at th i s timethat the LDRs w i l l only be p o t e n t i a l l y relevant and a p p r o p r i a t e forC E R C L A N S D W . L D R s _ , f f 6 n e r a l l V _ _ wi l l n o t f r e relevant a t t d . j B p p r q p r i a t efor CERCIA.SPW contaminated wi th wastes that are not known to..beRCRA hazardous .wa s t e s . , , T h e r e f o r e , as a mat t er of p o l i c y , theA g e n c y has determined that SDW g e n e r a l l y i s no t ' s u f f i c i e n t l ys i m i l a r ' to RCRA waste s , such that the use of LDRS is w e l l - s u i t e dto the circumstances at CERCXA sites." ( I & i d , p. 4-26, empha s i sin o r i g i n a l ) .

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F E A S I B I L I T Y S T U D Y - VOLUME I IA P P E N D I X AT R E A T A B I L I T V S T U D Y REPORT

A r k w o o d , I n c . S i t eoaaha, Arkansas

c

J a n u a r y 8, 1990W . O . #92-10

Prepared by;E R M - S O U T H W E S T , I N C ,16000 Memorial Drive, S u i t e 200H o u s t o n , Texa s 77079( 7 1 3 ) 496-9600

4043

S U M M A R Yn conducted in accordance with th« March 30, 1989" T r e a t a b i l i t y S t u d y W o r k P l a n " , evaluated several p o t e n t i a l treat-ment t e c h n o l o g i e s for a f f e c t e d so i l s at the A r k w o o d , I n c . site.T h e t e c h n o l o g i e s evaluated i n c l u d e d :

sieve-and-wash, using neutral water, water at e levatedpH, and water with s u r f a c t a n t s *Leach ing , us ing neutral tap water, water at pH 10 andperox idQ~water s o l u t i o n ;Wood removal;s t a b i l i z a t i o n ;Chemical o x i d a t i o n ;S l u r r y b i o l o g i c a l t r ea tment , both p r e t r e a t e d and notpre t r ea tad via chemical o x i d a t i o n ; andLand treatment.A soil s a m p l e was s epara t ed into coarse (+13 mesh) and s a n d / f i n e s(-12 me sh) f r a c t i o n s f o r t e s t i n g , T h e s e f r a c t i o n s were eharacter-i ™ . a s *?, r* l a t i v e f f i a s e and const i tuent concentrat ions . H e s u i t sof the soil c hara c t e r i za t i on i n d i c a t e that the coarse f r a c t i o n (+iim e s h ) repre sent s a p p r o x i m a t e l y 80% of the s i te s o i l , w h i l e thes a n d / f i n e s f r a c t i o n (-12 me sh) repre sent s th e remaining 2 D * , andtho concentrat ions ot c o n s t i t u e n t s of concern in the s i te L Ufe -p e n t a c h l o r o p h e n o l ( P C P ) a n d p o l y n u o l e a r aromatic hydro carbon s(PNAa) - increase with decreas ing p a r t i c l e size.

-both • P O P - a n e i - ' P H A

.washing should Depend ing on the eldanu|>reduce "clean" soilm t m u H A MM* 1 •* U * * i U J^"""'£i7"™»* t^«^*3*2»y i«sai»o53!ffigN5vv»*w^coarse ao i x s , wasning tn« s a n d / f i n e s frac t ion-^^"pgoduoo' a X a a n" — A ^ — — — ' — — — t J " " ' 1 d u e t o o th*i l i t a l f c t c t - ' ^ l u f f i ^ - f > f t ha-^aa t i i aH a n d

___ ____ __ ^ncreases w t h de crea s ing p a r t i c l eranging f r o m 11% naaa loas fo s- very coarse soil to B0% forsand-sised part io l«B. The e f f e c t o f a t t r i t i o n i s thata p p r o x i m a t e l y 66% of tho »it« «oil« remain es coarse material anda p p r o x i m a t e l y 34% are s a n d / f i n e s f o l l o w i n g eoil washing.L e a c h i n g ( s o i l washing with extended contact t i m e ) by i t a e l f doesnot a p p e a r to be unore e f f e c t i v e than coil washing with shortcontact t imes. However , l ea ch ing doaa a p p e a r to f u r t h e r reduce PCP

'."V

c-

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S t a b i l i z a t i o n is not a su i tab l e t e chnology for the Arkwood , I n c .site in that it r e su l t s in increased PCP m o b i l i t y in a f f e c t e ds o i l s e Fur th ermore , whi l e i m m o b i l i z a t i o n o f PNAs does occur withs t a b i l i z e d s o i l , i t i s o f l i t t l e b e n e f i t since n e g l i g i b l e l ea ch ingof PNAs occurs with untreated so i l .Chemical o x i d a t i o n only achieves a small percent reduction in bothPCP and PNAs concentration in the A r k v o o d , I n c . s o i l a . It i st h e r e f o r e not s u i t a b l e as a s tand-alone treatment method.s lurry b i o l og i ca l treatment ie e f f e c t i v e in reducing the concentra-tions of PCP and PNAs in the s a n d / f i n e s f r a c t i o n of the s i t e so i l s .PCP and PNAs concentrations are reducedby a p p r o x i m a t e l y 85% and 80%, r e sp e c t i v e ly . However, extendedtreatment time is required. The treatment appear s to reach ap l a t e a u a f t e r 56 days at a p p r o x i m a t e l y 300 m g / k g PCP. A f t e r $ H f c !days, the PCP and ?NAs were not detected in '?CLP leachataf r o m b i o l o g i c a l l y t r f l a t e d s o i l s . Oxidat ion pretreatmant does no tenhance b i o l o g i c a l d egrada t i on .Land treatment is not e f f e c t i v e for the A r k w o o d , Inc. site. Bio-*l o g i c a l d egrada t i on of organic cons t i tuent s does ocour using th i smethod, but too s l o w l y to be of prac t i ca l use.

ii3069

N O T U S E D I N C O A R S EF R A C T I O N W A S H I N GA F F E C T E DS O I L

S O I L S A M P L E 0 1S C R E E N / D E C A N T

SOIL SAMPLE 62S C R E E N / D E C A N T

~ SttL SAMPLE 03 IN"""" -12 MESH WASHINGS C R E E N / D E C A N T

W A S H E D S O I LS A M P L E S 1 I N C O A R S EF R A C T I O N W A S H I N O _ _ S P E N T W A T E R( S A M P L E 5 2 )

WOODSAMPLE $4 F I N E SS A M P L E S 3

WSiW A S H E D S O I L

SAMPLE $11 . S A M P L E D E S I G N A T I O N S N G U J t f DTOR CROSS-REFERENCE TO BtQTROl REPORTS,N O T U S E D I N C O A R S EF R A C T I O N W A S H I N G(EXCEPT TEST NO. w- 2 , F I N E S A N D W A T E R S E P A R A T E D tttOU W A S H E DS O I L B Y O C C A N T 1 M G I N - ' 2 U G S H W A S H I N G .5 . F I N E S A N D W A T E R S E P A R A T E D F R O M W A U H C Q S O I LBY SCRIEWWQ AT U MESH INW A S H I N G S .

4-tB E N C H - S C A L E S O I L W A S H I N GP R O C E S S F L O W D I A G R A MArkwood I n c . S i t eOrnoha, Arkansas

H O U S T O N , T C X A 9O R L E A N S , L O U I S I A N A

D A J g OV22/90

F o l l o w i n g the i n i t i a l t e s t s , it was de t ermined that the Coarse cf r a c t i o n night not be r epre s en ta t ive of the entire coarse f r a c t i o n .Two a d d i t i o n a l coarse f r a c t i o n s , Coarse "A" (-2" +1-1/4") andcoarse "B" ( - 3 / 4 1 1 + 1 / 2 " ) , were washed to inve s t iga t e how washinge f f e c t i v e n e s s varies with p a r t i c l e s ize , and to a l l o w e x t r a p o l a t i o nof the r e su l t s to the entire coarse f r a c t i o n . T h e s e two f r a c t i o n swere washed only with tap water.The test r e su l t s f or washing o f a l l three coarse soil f r a c t i o n sare summarized in T a b l e s 4-1, 4-2 (POP d a t a ) and 4*3 (PNA d a t a ) .The c o r r e s p o n d i n g Biotrol report and GSAX a n a l y t i c a l r epor t s are? rovided in A t t a c h m e n t B. PCP percent removals may be biased h i g hn the case of low PCP recoveries.The r e su l t s o f wa sh ing th e coarse f r a c t i o n s ind i ca t e th e f o l l o w i n g !

l.

2.

3.

4.

W a s h i n g p a r t i a l l y removes both PCP and PNAs f r o m th enoil. PCP removal appears to occur due to a combinationof d i s s o l u t i o n of PCP in water and a t t r i t i o n of a f f e c t e dsoil f r o m p a r t i c l e s u r f a c e s . PNA removal a p p a r e n t l yoccurs only due to a t t r i t i o n o f a f f e c t e d mater ia l f r o msoil p a r t i a l t i s u r f a c e s , since PNAs were not d e t e c t e d inthe aouoous phase.

The wash proce s s t r a n a f o r m s some of the coarse soil intof i n e r mater ia l . T h i s mass "lose" ( a t t r i t i o n ) increasedwith d e c r ea s ing p a r t i a l * s i c e / ranging f r o m 11% forCoarse A to 44% ( a v e r a g e ) for Coarse C. The e f f e c t o fth i s a t t r i t i o n is c a l c u l a t e d in S e c t i o n 4.4.For the coarse f r a c t i o n s , PCP removal a p p e a r s to improveas p a r t i c l e size increases.T e s t r e su l t s do not ind i ca t e that a d d i t i o n of s u r f a c t a n t sor e l evat ion of pK result in more e f f i c i e n t washing thanneutral water.

4.3S a n d washing waa inve s t iga t ed using a batch Denver a t t r i t i o n f l o t a -t ion device. A f t e r cons iderat ion o f l i k e l y means o f f u l l - s c a l esand washing, it was decided to wash the combined s a n d / f i n e s frac-tion arid sub s equent ly to remove the f i n e s * A t t r i t i o n f l o t a t i o ne m p l o y s a tank which is v igorou s ly a g i t a t e d by an i m p e l l e r tosuspend the p a r t i c l e s . P a r t i c l e s are cleaned by water turbulenceAn air a sp i ra t or can be used to aid inT h e f r o t h contains h y d r o p h o b i a organicThe remaining s o i l -wa t er s lurry is thenand p a r t i c l e abrasion,f o r m a t i o n o f a f r o t h ,compounds and soil f i n e s

4-3QMS

in the calculat ion shown in T a b l e 4-6. Based on this ca l cu la t i on ,washing coabined site s o i l s ( i n c l u d i n g s a n d / f i n e s ) y i e l d s 66** aswashed coarse soil and 34% as sand/ f i n e s for f ur th er treatment ord i s p o s a l .4.5 LeachingThe l each ing s tudy was carried out by a procedure s imilar to theTCLP method. A soil sample was placed in a container with theleach so lu t ion ( t a p water, water raised to pH 10 with caustic, orwater with hydrogen p e r o x i d e ) and tumbled for 72 hours. At theend of thi s time p e r i o d , the alurry was s eparat ed into washed s o i l ,f i n e s and water. Each f r a c t i o n was then a n a l y z e d for PC? andindicator P N A s .The leach test using all three leaoh so lu t ions was p e r f o r m e d onsoil ( s a n d / f i n e s ) a f t e r 28 days o f biotreatment to determine i fl ea ch ing could f u r t h e r reduce soil consti tuent concentrations.A f t e r reviewing the r e s u l t s o f these t e s t s , l ea ch ing was repeatedon untreated s a n d / f i n e s . S i n c e water at a high pH showed the beatremoval, the test was repeated on the Coarse C soil f r a c t i o n usingwater a d j u s t e d to pH 10. . R e s u l t s of the l each ing s tudy arepre s en t ed in T a b l e s 4-7 (POP d a t a ) and 4-8 (PNA d a t a ) .The r e su l t s o f these l each ing t e s t s ind i ca t e t h e f o l l o w i n g !

l. Peroxide-and-water s o lu t i on is no more e f f e c t i v e thanwater as a l ea ch ing so lu t ion.2. Elevat ed pH a p p e a r s to improve POP removal e f f i c i e n c

'3.

4.

Leaching by i t s e l f does not appear to be more, e f f e c t i v ethan soil washing with short contact times in theset e s t s . Leaching prev iou s ly washed soil y i e l d e dadd i t i ona l PCP removal.It is not c lear why b i o t r ta t ed soil should exhibitimprovement by l ea ch ing , cons ider ing that the slurrybiotreatment is somewhat of a l eaching proces s .

4.6 Wood Raipoyqlwood p a r t i c l e s were f o u n d in all soil f r a c t i o n s . T h i s wood con-tains a p p r o x i m a t e l y twice the concentrations of const i tuents ofconcern as the remainder of the soil. Loss-on-ignit ion (L01) te s t sin the initial s a n d / f i n e s washing t ea t s indicated that the sand/f i n e s might inc lude as much as 10% by weight of wood p a r t i c l e s and

4-119063

up to 20% of the to tal mass of PGP. Hood removal was t h e r e f o r ei n v e s t i g a t e d as f t p o s s i b l e means of lowering the f i n a l concentra-t i on s of const i tuent* of concern in washed s o i l , (The removed woodwould p r e s u m a b l y be i n c i n e r a t e d , )For the aand/ f i n e s f r a c t i o n , wood was removed f r o m washed soil by" j i g g i n g " , a process s imi lar to panning for g o l d . W o o d removalf r o m the coarse s o i l s by j i g g i n g wae u n s u c c e s s f u l . Wood removalus ing dense~phas* s epara t i on was t e s t ed for one coarse f r a c t i o n .T h i s proces s consisted of a d d i n g washed noil to a calcium ch l or id es o l u t i o n , which has a higher d en s i ty than water. ( W a t e r alone waeu n s u i t a b l e , since the wood has a s p e c i f i c gravi ty near that ofw a t e r . ) W o o d f l o a t e d on the dense s o lu t i on , and was removed.Very l i t t l e wood ( t y p i c a l l y l e s s than 1%) was removed in theset e s t s . It i s be l i eved that the L o s s - O n - I g n i t i o n (LOI) t e s t s over-e s t i m a t e the quant i ty of wood in the s a m p l e . W o o d removal has an e g l i g i b l e e f f e c t on the f i n a l concentration of PCP and PKAs in thewashed s o i l , and is t h e r e f o r e of no pra c t i ca l b e n e f i t .4 . 7 Discus s ion 6f f l a i l H a s h i n gBased on a review of all of the d a t a for soil wash ing, some con-c lu s i on s can be drawn about the mechanism* of cons t i tuent removaland how to o p t i m i z e f u l l - s c a l e to i l washing. For p a r t i c l e s ize sl ea s than a p p r o x i m a t e l y 1/4-inch ( s a n d , f i n e s , and some g r a v e l ) ,the c on s t i t u en t s of concern have a p p a r e n t l y pene tra t ed d e e p intot h e p a r t i c l e s . T h e r e f o r e , c l e a n i n g a n d / o r abrasion ( r e m o v a l ) o fthe p a r t i c l e s u r f a c e s alone i s i n s u f f i c i e n t to c o m p l e t e l y removec o n s t i t u e n t s o f concern. As p a r t i c l e siee decreases, d i f f u s i o np l a y s an i n c r e a s i n g l y important role in consti tuent removal. T h i sconclusion is s u p p o r t e d by biotr satment test r e su l t s ( d i s c u s s e d inS e c t i o n 7) .T e s t r e su l t s do not indica t e that a d d i t i o n of s u r f a c t a n t s ore l eva t i on of pH result in more e f f i c i e n t washing than neutralwater.D e p e n d i n g on the s e l e c t ed treatment g o a l , it is e xpec t ed that soilwashing wi l l produce:

"clean" coarse a n d / o r sand f r a c t i o n s ( i . e . ,i10 tob a o k f i l l e200 to *W$S8 m g / k g se s idual roPPCP andg t o ta l indicator PNAs) which may be• — ~v »on-tite.

a f i n e s f r a c t i o n which may achieve a residualconcentration! e f r l f l O Q - f a s ' I Q Q Q p p » a f t e r washingJ W M W 1^M S K M W S^ T h i s f r a c t i o n could be^ewatered andcapped on-site or undergo f u r t h e r treatment such asa d d i t i o n a l washing or b i o l o g i c a l t r ea tment .

4-15QW3

8 - CONCLUSIONSI .

2.

3.

4.

5.

The A r k w o o d , I n c . site so i l s contain a h igh percentageof cobble s and gravel. The coarse f r a c t i o n (+12 mesh)repre s ent s a p p r o x i m a t e l y 80% of the s i te s o i l , and thes a n d / f i n e s f r a c t i o n (-12 mesh) repre s ent s th e remaining20% (wet sieve b a s i s ) .In g e n e r a l , the concentration of c on s t i tu en t s of concernin the site s o i l s - p en tach loropheno l (FCP) and p o l y -nuclear aromatic hydrocarbons (PKAs) - increases withdecreas ing p a r t i c l e size.For t h e coarse f r a c t i o n , soil washing e f f i c i e n c y a p p s a r sto improve as p a r t i c l e size increases. D e p e n d i n g on thec l e a n u p level s e l e c t e d , some of the coarse s o i l s couldp r o b a b l y be washed to achieve the c l eanup criteria.W a s h i n g the s a n d / f i n e s f r & e t i o n to produce clean sand i snot prac t i ca l due to the l i m i t e d volume of the f r a c t i o nand the cost of treatment . T e s t re sul t s ind i ca t e thata d d i t i o n of s u r f a c t e .its and e l eva t ion of pK do not resulti n more e f f e c t i v e washing t h . ' * n neutral w a t e r ' i n eitherthe coarse or s a n d / f i n e s washing t e s t s . W o o d removalwould have n e g l i g i b l e e f f e c t on the f i n a l concentrationof POP and PKAs in the washed aoi1., and is t h e r e f o r e ofno prac t i ca l b e n e f i t .The wash process t r a n s f o r m s some of the soil into f i n e rmater ia l . T h i s mass "loss 1 1 ( a t t r i t i o n ) ' . ^ c r e a s e s withdecreas ing p a r t i c l e s ize , ranging f r o m 11% for verycoarse soil to 50% for sand-s ized p a r t i c l e s , f a l l o w i n gwashing, a p p r o x i m a t e l y 66% of the t o ta l soil mass remainsas coarse soil and a p p r o x i m a t e l y 34% as s a n d / f i n e s .D e p e n d i n g on the s e lec ted treatment g o a l , it is e xpe c t edthat soil washing w i l l produce!

"clean" coarse a n d / o r sand f r a c t i o n s ( i . e . ,— — — w g g B g g K ~W/ m»Tf — — — - » » » • . • . •m g / k g to tal indicator P N A s )jrwarrvur aHQ iO T*O w w g M g j u t * f / «>^ wwiwhioh may be b a c k f i l l e d on-sita.

a f i n e s f r a c t i o n whioh may achieve a residual •concentration! e f l - 3 ' G Q - t o 1POQ p p a a f t e r washingi W t t & g t t M f & f t ^ ^o a p p e t

«S*»«*M 111* ii ,tm.m otsnimutem_.,_s f r a c t i o n aou-,, __on-site or undergo f u r t h e ri I _ . _ • ! _ • • . . • • « a •

uewatereu ««*« waypwt t UH-BII.V oir utHswr^o cur^nez*treatment such as a d d i t i o n a l washing or b i o l o g i c a ltreatment8-1

6.

7.

6.

10.

11.

12.

Leaching (so i l washing with extended contact t i m e ) byi t s e l f does not a p p e a r to be more e f f e c t i v e than soilwashing with short contact times. However , l ea ch ing doesa p p e a r to f u r t h e r reduce PCP l ev e l s f o l l o w i n g soilwashing. Peroxide does not improve l eaching p e r f o r m a n c e ._ . , . , _ Mminmr i UriiMnf x i r u i i i Y i i i i l i h r f i l J i ~ i i < i r i f i i i n » nmm. min 11 11.b u t — R a i s i n g the BH lii improveSelween -10% an

H e e d removal hao- n e g l i g i b l e a f f e o t on f e h e f i n a l eehooneg ror and n i f t a - in waohod a a i l B j and lacf no p g t t o t i e f t f e b e n e f i t rWood removal was evaluated as ap o t e n t i a l enhancement to the soil washing proce s s , sinceit was determined that the wood contained above twice thePCP concentration of the remainder of the s o i l s , Woodremoval was a c compl i sh ed by two methods t J i g g i n g anddenae phase f l o t a t i o n . Very l i t t l e wood ( l e s s than 1%)va0 removed in these t e s t s . It was concluded that woodremoval has n e g l i g i b l e « f f e o t on the f i n a l concentrat ionof PCP and PNAs in washed s o i l s , and is t h e r e f o r e of noprac t i ca l b e n e f i t .S t a b i l i z a t i o n is not a s u i t ab l e t e c h n o l o g y for theA r X w o o d , I n c . site in that it r e su l t s in increased PCPmobi l i ty in a f f e c t e d f o i l s . Furthermore, while im-m o b i l i z a t i o n of PNAs does occur with s t a b i l i z e d s o i l , i ti s o f l i t t l e b e n e f i t since n e g l i g i b l e l each ing o f PNAsoccurs with untreated soil.Chemical o x ida t i on only achieves a smal l reduction (5% -2 0 % ) in both PCP and PNAs concentrations in the A r J c w o o d ,X n c . s o i l s . It is t h e r e f o r e not s u i tab l e as a stand--alone treatment method.S l u r r y b i o l og i ca l treatment is e f f e c t i v e in reducing theconcentration* of PCP and PNAs in the • and/ f i n e a f r a c t i o nof the site soil*. PCP andPNAB concentrations arereduced by a p p r o x i m a t e l y 85% and80%, r e sp e c t iv e ly . However, extended treatment time isrequired. The treatment appear s to reach a p l a t e a u a f t e r56 days at a p p r o x i m a t e l y 300 m g / k g P C P . A f t e r $£g| days ,the PCP and S l l p l S g f a FNAs were not de tec table in TCLPl e f t c h a t e f r o m b i o T o g F c a l l y treated s o i l s ,Oxidation pre treatment does not enhance b i o l o g i c a ldegradat i on .Land treatment is not e f f e c t i v e for the A r k w o o d , Inc.site. Biolog i ca l d e g r a d a t i o n of organic cons t i tuent s

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does occur using this me thod, but too s l o w l y to be ofprac t i ca l use.

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