### Superfua dRecord s Cente r SHE

- ^ ' Conno r

Ct > BREAK :

I N TH E UNITE D STATE S DISTRIC T COUR T FO RTH E DISTRIC T O FMAIN E SDM S DocI D 

### UNITE D STATE S O FAMERIC A

Plaintiffs , v . 

### F . O'CONNO RCOMPAN Y SUPERFUN D SITE , et . a l

Defendants . CIVI L ACTIO N NO .

AMENDMEN T T O CONSEN T DECRE E WHEREAS , thi s actio n wa s file db y th e Unite dState s o n behal f o f th e Unite dState s Environmenta l Protectio n Agenc y ("EPA" ) seekin g (1 ) reimbursemen t o f respons e cost s incurre d an dt o b e incurre dfo r

respons e action s a t

th e F . O'Conno r

Supcrfun dSit e i n Augusta . Main e (th e "Site"') , an d(2 ) performanc e o f studie s an drespons e action s a t th e Site pursuan t

t o th e Comprehensiv e Environmenta l Response , Compensation , an dLiabilit y Ac t ("CERCLA") . 4 2 \'.$ . C . § %01 . e t

seq. . a s amended , an dth e Resourc e Conservatio n an dRecover y Ac t ("RCRA") , 4 2 U.S.C . § 690 1 etseq. ; WHEREAS , o n Jul y 26 , 1990 . th e Cour t entere daConsen t

Decre e ("th e Consen t Decree" ) lodge db y th e Unite dState s t o resolv e thi s action ; WHEREAS , th e Consen t Decre e i n accordanc e wit h th e Statemen t o f Wor k (SOW ) calle dfo r sourc e contro l throug h on-sit e treatmen t b y solven t

extractio n o f

sit e soil s an d 27469 1sediments , managemen t o f migratio n throug h th e establishmen t o f temporary institutiona l control s unti l groundwate r remediatio n level s ar e achieved , th e constructio n an doperatio n o f a groundwate r

extractio n an dtreatmen t syste mt o remov e an dtrea t groundwate r

contaminate dwit h PCBs , benzene , an d1, 4 dichlorobenzene , on-sit e groun dwate r discharg e system , an d groundwate r

monitoring . WHEREAS , fro m199 1 t o 199 3 a n evaluatio n o f th e solven t

extractio n technolog y fo r contaminate dsoi l an dsedimen t wa s performe da s allowe db y th e Consen t Decre e i n accordanc e wit h th e SOW . Th e evaluatio n conclude dtha t th e technolog y woul dno t attai n th e performanc e standard s fo r

soil s an dsediment s se t

i n th e ROD . I n Jul y 199 4 EP A issue da n Explanatio n o f Significan t

Difference s (ESD ) whic h modifie dth e sourc e contro l portio n o f th e remedy . Soi l an d sedimen t containin g mor e tha n te n part s pe r millio n (ppm ) PCB s o r

cPAH s o r

24 8 pp mlea d woul db e treate dusin g solven t extractio n technology , the n transporte dan ddispose do f offsit e t o a n appropriat e facility . Alternatively , th e ES D provide dacontingenc y tha t thi s materia l coul db e sen t offsit e fo r

disposa l withou t

treatment . Soi l an dsedimen t containin g betwee n on e t o te n pp m PCB s o r cP.AH s woul dh e consolidate dini o on e are aonsit e an dthe n covere dwit h twelv e inche s o f clea n fil l brough t

i n fro moffsite . WHEREAS , i n Octobe r

1995 . EP A invoke dth e contingenc y remed y se t fort h i n th e 199 4 ESD . Thi s allowe dfo r

th e offsit e disposa l o f

soi l an dsedimen t

wit h greate r

tha n te n pp mPCB s an dcPAH s withou t

firs t requirin g on-sit e solven t extractio n treatment . Wherea s th e 199 4 ES D conceptuall y delineate dafive-side dare awher e soi l an dsedimen t containin g betwee n on e an dte n pp mPCB s o r cPAH s woul db e consolidated , followin g completio n o f

th e sourc e contro l thi s designate dare aha devolve dint o atwenty-five-side darea .

### Th e designate dare awil l b e surveyed , th e boundarie s simplifie dt o th e 10-side dshap e show n i n

Appendi x III , an dpermanen t marker s place dat

th e turnin g points . WHEREAS , i n 199 2 groundwate r pum p test s wer e conducte dan dseparat e phas e oi l wa s foun di n bedroc k

wells , aconditio n tha t

wa s no t detecte da t

th e tim e th e Consen t

Decre e wa s entered . Furthe r

investigatio n foun dtha t

althoug h ther e wa s separat e phas e oi l i n th e bedrock , i t appeare dt o b e confine dt o alimite dportio n o f th e Site , an dtha t

dissolve dconcentration s o f PCB s an dsolvent s downgradien t were onl y slightl y elevated . WHEREAS , i n 199 6 an d1997 , effort s wer e focuse do n oi l recover y fro mth e groundwate r

t o assis t i n th e sourc e contro l excavatio n rathe r tha n groundwate r

extractio n an d treatmen t o f dissolve dcontaminant . Followin g passiv e recover y o f oil , vacuum-enhance doi l recover y o f

separat e phas e oi l continue di n 2001 , recoverin g mor e tha n 2 0 gallon s o f oi l fro mth e bedrock . O n Jun e 4 , 2002 , Centra l Powe r Main e (CMP ) submitte dt o EP A an dMain e Departmen t

o f Environmenta l Protectio n (Main e DEP ) aTechnica l Impracticabilit y ("TI" ) Evaluatio n Repor t

assessin g th e feasibilit y o f remediatin g groundwate r contaminatio n a t

th e Site . Th e T I evaluatio n conclude dtha t becaus e o f

th e geolog y an dhydrolog y o f th e Site , ther e wer e n o technologie s tha t

coul drestor e th e groun dwate r beneat h alimite dportio n o f th e Sit e t o drinkin g wate r qualit y withi n areasonabl e time . EPA . afte r revie w an dcommen t

fro mMain e DEP , agree d\\ii h thi s conclusio n an dapprove dth e repor t i n Jun e 2002 . O n Jun e 1 9 . 2002 . pursuan t t o Sectio n 11 7 o f

CERCLA , 4 2 U.S.C . §9617 , EP A publishe danotic e o f th e availabilit y fo r

publi c revie w o f th e T I repor t

an dth e propose dpla n fo r amendin g th e remedia l actio n an dprovide d opportunit y fo r

publi c comment . WHEREAS , EP A an dth e Stat e hav e agree dtha t remediatio n o f

th e groundwate r

i stechnicall y impracticable , an dEPA , wit h th e concurrenc e o f th e State , issue do n Septembe r 26 , 200 2 aRecordo f

Decisio n Amendmen t

(th e "RO D Amendment") , whic h modifie s th e remedy fo r remediatio n o f

th e groundwate r

tha t wa s selecte di n th e Recordo f Decisio n issue di n 1989 . WHEREAS , thi s Amendmen t t o th e RO D provide s fo r th e protectio n o f

huma n healt h b y providin g fo r

lon g ter mmonitorin g o f groundwater , activ e an dpassiv e oi l recover y i n groundwate r

an darestrictiv e covenan t betwee n CM P an dMain e DE P tha t prohibit s th e us e o f groundwate r

withou t prio r approva l o f

Main e DEP . Thi s Amende dConsen t Decre e incorporate s th e RO D Amendmen t

an dal l it s attendan t

responsibilities , requirement s an dobligation s thereb y makin g i t a n enforceabl e part

o f th e Consen t

Decree . WHEREAS , th e Unite dState s an dth e Settlin g Defendan t hav e agree dt o amen dth e Consen t Decre e a s se t

fort h belo w t o modify th e obligation s o f th e Settlin g Defendan t

t o perfor m certai n respons e action s an dt o reimburs e cost s t o th e Unite dStates . Th e Partie s agre e tha t thi s i s amateria l modificatio n t o th e Consen t Decree . WHEREAS , unde r

Paragrap h 10 8 o f

th e Consen t

Decree , an y materia l modificatio n o f th e Consen t

Decre e mus t

b e i n writin g an dapprove db y th e Court : NOW , THEREFORE , th e Unite dState s an dth e Settlin g Defendant , i n consideratio n o f th e promise s an dcovenant s herein , an dintendin g t o b e legall y boun dthereby , agre e t o th e followin g modification s t o th e Consen t Decree : 1 . Al l term s an dphrase s i n thi s Amendmen t shal l b e define da s provide di n th e Consen t Decre e excep t

a s specificall y provide dherein . 2 . Th e right s an dobligation s o f th e Settlin g Defendan t

an dth e Unite dState s ar e no t modifie dexcep t

a s specificall y provide di n thi s Amendment .

### 3 . Sectio n IV . shal l b e amende da s follows : Paragrap h 3 shal l includ e th e followin g ne w an damende ddefinitions : "Consent Decree " shal l mea n th e Consent Decre e entere db y thi s Court o n Septembe r

10 , 1991 , an dthi s Amendmen t t o th e Consen t

Decree . "Designate dArea " shal l mea n th e are aconceptuall y identifie di n th e 199 4 BS D an dthe n delineate ddurin g post-sourc e contro l remedia l activities , wher e soil s containin g PCB s a t

concentration s o f

les s tha n 1 0 part s pe r

millio n bu t

abov e on e part pe r million , wer e consolidated . Thi s are ai s depicte di n Appendi x II I t o thi s Amendmen t

t o Consen t

Decree . "Explanatio n o f

Significan t

Difference " o r

"ESD " shal l mea n th e EP A Explanatio n o f

Significan t

Difference s relatin g t o th e Sit e signe do n Jul y 11 , 199 4 b y th e Regiona l Administrator . EP A Regio n I , an dattachment s thereto . "Recor do f

Decision " o r

"ROD " shal l b e amende dt o rea da s follows : "Recor do f Decision " o r

"ROD " shal l mea n th e EP A Recor do f Decisio n relatin g t o th e Sit e .signe do n Septembe r

27 . 19RQ . b y th e Actin g Regiona l Administrator . EP A Regio n 1 , an dal l attachment s thereto , an dth e Recor do f Decisio n Amendment . Operabl e Uni t

2 . signe do n Septembe r

26 . 200 2 b y th e Directo r

o f th e Offic e o f Sit e Remediatio n an dRestoration . EP A Regio n 1 an dal l attachment s thereto . Th e RO D i s attache da s Appendi x I t o th e Consen t Decre e an dth e RO D Amendmen ti s attacheda s Appendi x I t o thi s Consen t Decre e Amendment . "Site " shal l b e amende dt o rea da s follows : "Site " shal l mea n th e 23-acr e parce l define di n th e RO D Amendmen t an dRestrictiv e Covenant , locate dwithi n a twenty-eigh t

acr e parce l owne db y Settlin g Defendant . Wit h th e conclusio n o f th e sourc e contro l remedia l action , principa l feature s o f th e Sit e includ e th e uplan d marsh , adir t

roa dthroug h th e cente r

o f th e Site , th e tw o forme r

lagoons , no w restore da s wetlands , an dvariou s monitorin g wells . Thi s are ai s depicte di n Figur e 5 o f

Appendi x I t o thi s Amendmen t t o Consen t

Decree . "Statemen t

o f Work " o r

"SOW " shal l b e amende dt o rea da s follows : "Statemen t o f Work " o r

"SOW " shal l mea n th e statemen t o f wor k fo r implementatio n o f

th e remedia l design , remedia l action , an doperatio n an dmaintenanc e o f th e remed y a t th e Site , a s se t

fort h i n Appendi x I I t o th e Consen t Decree , th e 199 4 revise dSO W \\hic hwa s attache dt o th e 199 4 ESD . an dth e 200 3 Statemen t o f Wor k a s se t fort h i n Appendi x I I t o thi s Amendmen t t o th e Consen t

Decree . I f

aconflic t arise s betwee n th e Statemen t

o f Wor k i n Appendi x I I t o th e Consen t Decre e an dth e 200 3 Statemen t

o f Work , th e 200 3 Statemen t o f Wor k shal l control . "Technica l Impracticability " or'TI " waive r shal l mea n th e determinatio n mad e b y EPA . Regio n I . an dincorporate di n th e RO D Amendment , tha t i t i s technical! ) infeasibl e t o restor e th e groundwate r beneat h alimite dportio n o f th e Sit e t odrinkin g wate r standard s withi n areasonabl e tim e frame . Thi s are ai s depicte di n Figur e 3 o f

Appendi x I t o thi s Amendmen t t o Consen t

Decree .

4 . Sectio n VI . Performanc e o f th e Work

b y Settlin g Defendan t

shal l b e amende dfollows : Paragrap h 8.b . delet e "pumpin g an dcarbo n adsorptio n treatmen t o f contaminate d groundwater " an dinser t

"activ e oi l recover y implemente dannuall y an dpassiv e oi l recover y implemente dth e remainde r o f th e year. " Paragrap h 14.k. , inser t

th e followin g sentenc e a t th e en do f

th e paragraph : "fo r purpose s o f

th e Amende dConsen t

Decre e th e Settlin g Defendan t shal l submi t

t o EP A tw o boun d(2 ) an don e (1 ) unboun dcop y o f eac h Wor k

Pla n an dan y othe r submissio n require db y i t o r thi s Amendmen t

t o Consen t

Decre e o r

th e 200 3 SOW. " Paragrap h 16 . shal l h e amende db y addin g th e followin g languag e t o th e en do f th e firs t sentence : "an dth e Cleanu p an dPerformance s Standard s se t fort h i n th e 200 3 SOW . Appendi x I I t o thi s Amendmen t t o Consen t

Decree. "

5 . Sectio n IX . Qualit y Assurance ; Sampling , shal l b e amende da s follows : Paragrap h 24 . inser t

th e followin g sentene e a t th e en do f

th e paragrap h tha t

state s "fo r purpose s o f

th e Amende dConsen t

Decre e th e Settlin g Defendan t shal l submi t t o EP A quarterl y progres s report s a s describe di n Sectio n X I o f thi s 7

### Consen t Decree , o r

les s frequentl y a s agree dt o b y th e projec t coordinators . Th e Settlin g Defendan t

shal l submi t

t o EP A an dMain e DE P th e quarterl y report s o n Januar y 10 , Apri l 10 , Jul y 1 0 an dOctobe r 1 0 o f eac h calendar

year , beginnin g wit h th e quarte r

tha t follow s entr y o f

thi s Amendmen t

t o Consen t

Decree , unles s th e frequenc y ha s bee n change db y agreemen t o f th e projec t

coordinators. " Paragrap h 25 , inser t

th e followin g sentenc e a t th e en do f

th e paragraph : "fo r purpose s o f

th e Amende dConsen t

Decre e th e Settlin g Defendan t shal l notif y EP A an dth e Stat e n o les s tha n fourtee n (14 ) day s day s i n advanc e o f an y sampl e collectio n activity. "

7 . Sectio n XI . Reportin g Requirement s shal l b e amende da s follows : Paragrap h 30 , inser t

th e followin g sentenc e a t th e en do f

th e paragraph : "fo r purpose s o f

th e Amende dConsen t

Decre e th e Settlin g Defendan t shal l submi t

t o EP A tw o (2 ) copie s o f

quarterl y progres s reports. "

8 . Sectio n XVIII . Reimbursemen t o f Respons e Cost s shal l b e amende da s follows : Paragrap h 55 . inser t

th e follouin g sentenc e n t th e en do f

th e paragraph : "fo r purpose s o f

th e Amende dConsen t

Decre e th e Settlin g Defendan t shal l mak e paymen t b y mean s o f

acertifie dchec k

mad e payabl e t o "EP A i la/ardou s Substance s Superfund. " an dreferencin g th e O'Conno r Co . Superfun dSit e Specia l Account. "

### 9 . Sectio n XXVIII . Notice s an dSubmission s shal l b e amende da s follows : Paragrap h 106 , "A s t o th e Unite dStates " delet e "EP A RPM , O'Conno r

Co . Superrun dSite , Main e an dVermon t Superfun dSection , Wast e Managemen t Divisio n (HPS-CAN2) , J.F.K . Federa l Building , Boston . M A 02203 " an dreplac e wit h "EP A RP M - O'Conno r

Compan y Superfun dSit e Maine , Vermont , an dConnecticu t Superfun dSectio n (HBT ) U S EP A Regio n I On e Congres s Stree t Suit e 110 0 Boston , M A 02114 " 11 . Sectio n XXIX . Effectiv e Dat e shal l b e amende da s follows : Paragrap h 107 , afte r

th e firs t sentenc e ad dth e followin g sentence : "Th e effectiv e dat e o f thi s Amendmen t

t o Consen t

Decre e shal l b e th e dat e thi s Amendmen t t o Consen t Decre e i s entere db y th e U.S . Distric t Cour t fo r th e Distric t

o f Maine. "

S O ORDERE D THI S DA Y O F

l : 

### NITF. D STATI- S DISTRIC T .Il'DGF .

### S O AGREED : FO RTHE UNITE D STATE S

Thoma s L . Sansonett i Assistan t Attorne y Genera l Environmen t

an dNatura l Resource s Divisio n

DATE D Ro n Gluck , Assistan t Sectio n Chie f Environmenta l Enforcemen t Sectio n 142 5 Ne w Yor k

Avenue , N.W . Roo m1306 3 Washineton . D.C . 2000 5

1 0

### DATED Patric k Case y Environmenta l Enforcemen t Sectio n 142 5 Ne w York

Avenue , N.W . Roo m1306 3 Washington , D.C . 2000 5

Paul aSilsb y Assistan t Unite dState s Attorne y Distric t o f Main e U.S . Departmen t

o f Justic e Pos t Offic e Bo x 971 8 Portland . Main e 04104-501 8 DATE D

### FO RTH E UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

DATE D 9-23-0- 3

DATE D Robert W . Varney , Regiona l Administrato r U.S . Environmenta l Protectio n Agenc y Ne w Englan dRegio n 1 Congres s Street , Suit e 110 0 Boston , M A 02114-202 3

Suzann e Childfes s Senio r Enforcemen t

Counse l U.S . Environmenta l Protectio n Agenc y Ne w Englan dRegio n 1 Congres s Street , Suit e 110 0 (SES ) Boston , M A 02114-202 ?



### 1 2

### TH E UNDERSIGNE D SETTLIN G DEFENDAN T enter s int o thi s Consen t Decre e relatin g t o th e O'Conno r Compan y Superfun dSit e

FO RCENTRA L MAIN E POWE RCOMPAN Y Q°t/(£/C> ? Signature : ( T ^ . Dat e Name : R . Stot t Mahone y Title : Managin g Attorne y Address : 8 3 Ediso n Driv e

Augusta , Main e Agen t Authorize dt o Accep t

Servic e o n Behal f

o f Centra l Main e Powe r

Compan y Nam e (print) : t > . Title : Address : Telephone :

### APPENDI X I T O AMENDMEN T T O O'CONNO RCONSEN T DECRE E SEPTEMBE R200 2 RECOR D O FDECISIO N AMENDMEN T

### cute : 

# m

DATE : SUBJ : FROM : THRU : TO : 

### Unite dState s Environmenta l Protectio n Agenc y On e Congres s Street , Suit

e 110 0 Boston , MA 02114-202 3 

### MEMORANDU M Septembe r 25 , 200 2 F . O'Conno r

Compan y Superfun dSit e Recor do f Decisio n Amendmen t 

### f Drc r 

### '-

- '' I t A.r^ « . . u ^ i

>>——-———" • -~-~-TM,. TM -J^ J



### Terrenc e Connell y Maine , Vermont , & Connecticu t Superfun dSectio n Mary Jan e O'Donnell , Sectio n Chie f / _ Maine , Vermont , & Connecticu t SuperftMfl^Sectio n Richar dCavagnero , Actin g Directo r f M OSRR/ / f < • 

### Summary o f

Actio n Attache dfo r

you r revie w an dsignatur e i s th e Recordo f Decisio n Amendmen t

(RO D Amendment ) fo r

th e F . O'Conno r

Compan y Superfun dSite , th e (Site ) i n Augusta , Maine . Thi s documen t

amend s th e remedia l actio n originall y selecte di n th e 198 9 RO D fo r th e managemen t

o f migratio n operabl e uni t

(OU-2) . Afte r

i t i s full y execute dan drecorded , thi s RO D Amendmen t

wil l becom e par t

o f th e Administrativ e Recor dfo r publi c revie w In addition , anotic e whic h briefl y summarize s thi s ROD Amendmen t wil l be publishe d i n amajo r loca l newspape r

o f general circulation . Th e RO D Amendmen t

addresse s th e remedia l actio n objectiv e o f preventin g exposur e t o contaminate dgroundwate r throug h institutiona l controls . Th e Amendmen t change s th e 198 9 managemen t

o f migratio n componen t

whic h relie do n pump-and-trea t o f th e groundwate r

t o activ e oi l recovery fro mth e overburde n soi l an dbedrock , long-ter m monitoring , an dth e establishmen t o f atechnica l impracticabilit y zon e fo r alimite dare a o f th e Site . Chemical-Specific ARAR s fo r PCB s an dseve n VOC s ar e bein g waive di n a n are awher e residua l separat e phas e oi l remain s fiv e year s afte r th e successfu l completio n o f th e sourc e contro l remedia l action . Majo r Issue s EP A ha s determine dtha t

i t i s technicall y impracticabl e fro ma n engineerin g perspectiv et o attai n federa l an dstat e drinkin g wate r

standard s fo r

alimite dportio n o f

thi s Site , an di s thu s waivin g attainment

o f thes e ARARs . EPA ha s determine dtha t activ e remedia

l actio n to recove

r th e separat

e phas e oi l i n th e overburde n soi l an di n th e bedroc k

wil l reduc e the volume o f

hazardou s substance s an dreduc e the possibilit y o f it s mobilit

y t o other portion s o f

th e She . Therefore , thi s remedy satisfie s th e statutory preferenc e fo r remedie s tha t

utiliz e treatmen t

a s aprincipal elemen t

t o reduc e th e toxicity , mobility , o r volum e o f

hazardou s substances . A n evaluatio n o f

th e exposure pathway s an drisk s associate dwit h th e Sit e wa s performed i n Jun e 200 2 a s part

o f th e firs t five-yea r revie w fo r

th e Site . Thi s evaluatio n conclude d tha t th e exposur e pathway s an drisk s applicabl e t o groundwate r ha dno t change dsinc e th e 198 9 ROD . Thi s informatio n wa s incorporate dint o th e RO D Amendment , supportin g th e T I waiver . N o furthe r

constructio n fo r

remedia l actio n i s anticipate dfollowin g thi s RO D Amendmen t

a s th e component s o f

th e selecte dremedy are already i n plac e an dth e sourc e contro l ha s bee n successfull y completed . A s such , aPreliminary Clos e Ou t Repor t fo r th e Sit e ha s als o bee n prepare dfo r thi s fisca l year . Headquarter s Perspective/Involvemen t Headquarter s wa s consulte dregardin g th e technical impracticabilit y waive r an dth e reassessmen t

o f ARARs . Headquarter s reviewe dth e RO D Amendmen t an dthei r comment s hav e bee n addressed . Publi c Involvement Ther e ha s bee n limite dpubli c involvemen t associate dwit h thi s sit e followin g th e successfu l remediatio n o f th e sourc e contro l are a(OU-1 ) i n 1997 . Publi c notic e wa s give n i n Jun e 200 2 regardin g th e Propose d Plan t o amen dth e 198 9 ROD . Thi s publi c notic e include dapres s releas e t o th e majo r loca l pape r a s wel l a s amailin g t o al l neighbors . A t

apubli c informatio n meeting , th e publi c expresse dsuppor t fo r th e propose dremedy . Media-Congressional Involvemen t Ther e wa s medi acoverag e o f th e publi c meetin g hel dfo r th e Propose dPlan . N o member s o f

th e publi c o r

medi aattende dth e publi c hearing . Ther e ha s bee n n o congressiona l involvemen t regardin g thi s RO D Amendment . Stat e Coordinatio n Main e DE P wa s activel y involve di n th e technical impracticability evaluatio n fo r OU-2 . Main e DE P reviewe dth e draf t Propose dPla n an dentere dforma l comment s a t th e publi c hearing . I n additio n t o their participatio n i n th e OU- 2 RO D amendment , Main e DE Pals o provide dcomment an dpropose dmino r

change s t o th e OU- 1 an dOU- 3 remedies . Finally , Main e DE P als o activel y participate di n th e firs t five-yea r fo r th e entir e site , a proces s whic h occurre d durin g th e sam e time period . Main e DEP ha s concurre dwit h thi s RO D Amendment . Recommendatio n Th e selecte dremedy i s protectiv e o f huma n healt

h an dth e environment , attain s o r provide s th e basi s fo r

awaive r o f federa l an dstat e requirement s tha t ar e ARAR s fo r

thi s remedia l action , an di s cost-effective . Therefore , w e recommen dyo u sig n thi s RO D Amendment . Contac t Person s Terrenc e Connelly , Remedia l Projec t Manager , 918-137 3 Ron aGregory , Senio r

Enforcemen t

Counsel , 918-109 6 Attachment : Recor do f

Decisio n Amendmen t

## Site : O

_



## F . O'CONNO RCOMPAN Y SUPERFUN D SIT E RECOR D O F DECISIO N AMENDMEN T

OPERABL E UNI T 2

Septembe r

200 2 U.S . Environmenta l Protectio n Agenc y - Regio n I

Ne w Englan dDECLARATIO N FOR*THE : RECOR D O F DECISION AMENDMEN T A . SIT E NAM E AN D LOCATIO N F . O'Conno r

Compan y Superfun dSit e Augusta , Kennebe c County , Main e CERCLI S Identificatio n Number : MED98073147 5 PRPLea d Operabl e Uni t

Two , Managemen t

O f Migratio n B . STATEMEN T O F BASI S AN D PURPOS E Thi s decisio n documen

t present s a

n amendment

to th e selecte

dremedia l actio n fo r

th e F . O'Conno r Compan y Superfun dSit

e i n Augusta , Main e whic h wa s chose n i n accordanc e wit

h th e Comprehensiv e Environmenta

l Response , Compensation , an dLiabilit y Ac t o f 198 0 (CERCLA) , a s amended , 4 2 U.S.C . § § 960 1 ct . seq . an dth e Nationa l Oi l an dHazardou s Substance s Pollutio n Contingenc y Pla n (NCP ) a s amended , 4 0 C.F.R . Par

t 300 . The Director

o f the Offic e o f

Sit e Remediatio n an dRestoratio n ha s bee n delegate dth e authorit

y to approv e thi s Recor

do f Decisio n Amendment

(RO D Amendment). . Thi s decisio n wa s basedo n th e Administrativ e Record , whic h ha s bee n develope di n accordanc e with Sectio n 11 3 (k) o f

CERCLA , an dwhic h i s availabl e fo r revie w a t th e Lithgo w Publi c Library i n Augusta , Main e an da

t th e Unite dState s Environmenta l Protectio n Agenc y (EPA ) Regio n 1 Offic e o f Sit e Remediatio n an dRestoratio n (OSRR ) Record s Cente r i n Boston , Massachusetts . The Administrativ e Recor dInde x (Appendix B o f

thi s RO D Amendment) identifie s each o f th e item s comprisin g th e Administrativ e Recor

dupo n whic h th e selectio n o f th e remedia

l actio n i s based . "Di e Stat e o f

Main e ha s concurre dwit h th e selecte dremedy . C . ASSESSMEN T O F THE SITE Th e respons e actio n selecte di n thi s RO D Amendmen t i s necessar

y t o protec t

th e publi c health o r

welfar e o r th e environmen t

fro mactua l o r

threatene drelease s o f

hazardou s substance s int o th e environment . D . DESCRIPTIO N O F TH E SELECTE D REMED Y Thi s RO D Amendment

change s th e remed y originall y selecte di n th e 198 9 RO D fo r th e managemen t

o f migratio n operabl e uni t

(OU-2) . Thi s RO D Amendmen t make s mino r

change s an dclarification s t o th e sourc e contro l an dRigg s Broo k remedie s (OU- 1 an dOU-3 , respectively) . Th e majo r

component s o f

th e selecte dremed y include :

• Institutiona

l control s to preven t

th e us e o f

contaminate dgroundwater ;

• Waive

r o f federa l an d state drinkin g wate r standard s fo r

alimite dportio n o f

th e Site o n the basi s o f

technica l impracticability ;Activ e recover y o f separate-phas e oi l fro mthe overburden soi l an dbedroc

k throug h annua l implementatio n o f

avacuum-enhance drecover y syste man dpassiv e recover

y betwee n thes e annua

l implementations ; Long-ter mmonitorin g o f

sit e groundwater

o n aregula

r basi s t o evaluat e change s i n sit

e condition s ove

r time ; and A review o f

th e Sit e ever y fiv e year s to ensure that

th e remedy remain s protectiv e o f human healt

h an dth e environment . E . STATUTOR Y DETERMINATION S Th e selecte

dremed y for OU- 2 i s protectiv e o f

human healt

h an dth e environment , complie s wit h Federa l an dStat e requirement s tha

t ar e applicabl e o r

relevant an dappropriate to th e remedia l actio n (unles s justifie db y awaiver) , i s cost-effective , an dutilize s permanen t solution s an dalternativ e treatmen t (o r resourc e recovery ) technologie s to th e maximu mextent practicable . Th e remed

y als o satisfie s th e statutor y preferenc e fo r

treatment a s aprincipa

l elemen t a s th e activ e oi l recover y syste mprovide s reductio n i n toxicity , mobility , an dvolum e o f contaminant s throug h th e extractio n an dtreatment

o f separate-phas e PCB-lade n oil . Becaus e thi s remed

y will resul

t i n hazardou s substance s remainin g on-sit e abov e level s that

allo w for unlimite dus e an dunrestricte dexposur e (groundwate r

and/o r lan dus e restriction s ar

e necessary) , a review wil l b e conducte dever y fiv e year s afte r

initiatio n o f

remedia l actio n to ensur

e tha t th e remedy continue s to provid e adequat e protectio n o f

human healt

h an dth e environment . 

### F . SPECIALFINDING S Issuanc e o f

thi s RO D embodie s specifi c determination s mad e b y th e Regiona l Administrato r o r hi s designe e pursuan t

t o CERCLA . EP A determine dtha t i t wa s technicall y impracticabl e t o restor e groundwate r

beneath alimite dare ao f

th e Sit e t o drinkin g wate r

quality withi n areasonabl e tim e frame . Therefore , EPA waive dth e attainment o f chemical-specifi c ARAR s fo r thi s are ao f

th e She . Thes e chemical-specifi c ARAR s ar e eithe r bein g met no w or ar e expectedto b e met

shortl y throughou t

th e res t o f th e Site , an dtherefor e wil l provid e sufficien t basi s fo r EP A t o make astatutor

y findin g o f

complianc e fo r th e chemical-specifi c ARAR s presente di n thi s RO D Amendmen t fo r th e res t o f th e Sit e 

### G . RO D DAT A CERTIFICATIO N CHECKLIS T Th e followin g informatio n i s include di n th e Decisio n Summary sectio n o f thi s Recor

do f Decisio n Additional informatio n can b e foun di n th e Administrativ e Recor dfil e fo r thi s Site . 1 . Chemical s o f

concer n (COCs ) an dthei r

respectiv e concentrations . 2 . Cleanu p level s establishe dfo r COC s an dth e basi s fo r

th e levels . 3 . Curren t

an dreasonably anticipate dfutur e lan dassumption s an dcurren t an dpotentia

l futur e beneficia l use s o f

groundwater

use di n th e RO D Amendment .4 . Potentia l lan dan dgroundwate r

us e that wil l b e availabl e a

t th e Sit e a s aresul t

o f th e selecte d remedy . 5 . Estimate dcapital , operatio n an dmaintenanc e (O&M) , an dtota l present wort h costs ; discount rate ; an d the number

o f year s ove r whic h the remed

y cost estimate s ar

e projected . 6 . Ke y factor(s ) that le dt o selecting th e remedy . 

### H . AUTHORIZIN GSIGNATURE S Thi s RO D Amendmen t

document s th e selecte dremed y fo r th e F . O'Conno r

Superfun dSite , Operabl e Uni t 2 . Thi s remed

y wa s selectedb y USEP A wit h concurrenc e o f

th e Main e Department

o f Environmental Protectio n (MEDEP) . U.S . Environmenta l Protectio n Agenc y

B y avagnero y Actin g Directo r

Remediatio n an dRestoratio n Regio n 1

### Tabl e o f Content s I . SIT

E NAME , LOCATION , DESCRIPTIO N AND RATIONAL E FO R AMENDMENT II . SITE HISTOR Y AN D ENFORCEMEN T ACTIVIT Y 3 III . COMMUNIT Y PARTICIPATIO N 5 IV . SCOPE AN D ROLE O F OPERABLE UNI T 5 V . DESCRIPTIO N O F CHANGE S T O TH E 198 9 REMED Y 6 DESCRIPTIO N O F THE 198 9 REMED Y 6 CHANGE S T O THE 198 9 REMED Y 8 VI . SUMMARY O F SITE CHARACTERISTIC S 9 VII . SUMMAR Y O F SIT E RISK S 1 4 VII I TECHNICAL IMPRACTICABILIT Y DETERMINATIO N 1 5 IX . COMPARATIV E ANALYSI S O F TH E ORIGINA L REMED Y AN D OU- 2 ALTERNATIVE S 2 9 X . TH E SELECTED REMED Y , 3 6 XT . STATUTORY DETERMINATION S 3 9 XII . DOCUMENTATIO N O F N O SIGNIFICAN T CHANGE S 4 3 XIII . STATEROL E 4 3

### Figure s

1 . Sit e Locatio n Ma

p 2 . Sit e Plan 3 . T I Zon e 4 . Restrictiv e Covenan t 5 . Designate dArea , 1994 , 1997 , an d200 2 6 . TW A I I 7 . Site Plan wit

h Cros s Section s 8 . Geologi c Cros s Sectio n A - A ' 9 . Geologi c Cros s Sectio n B - B ' 10 . Geologi c Cros s Sectio n C - C ' 11 . Uplan dMars h Stud y Are a 12 . Vertical Residua l Oi l Distributio n A - A ' 13 . Vertical Residual Oi l Distributio n B - B ' J4 . Vertical Residua l Oi l Distributio n C - C ' 15 . Inferre dBedroc k

Surfac e Elevatio n 16 . Inferre dGroundwate r Flo w 17 . Conceptual Hydrogeologi c Mode l prio r to SCRA 18 . Conceptua l Hydrogeologi c Mode l Afte r SCR A 

### Table s 1 . Compariso n betwee n 198 9 RO D an d200 2 RO D Amendmen t 2 PC B Result s - TW A I I 3 . Chemical-Specifi c ARAR s fo r T l Waive r 4 . Gallon s o f

Oi l RecoveredFro mTWA I I Are aWell s 5 . Summar

y o f Groundwater

Monitorin g Result s ModifiedMetho d68 0 6 . Chemical-specifi c ARAR s 7 . Location-specifi c ARAR s 8 . Action-specifi c ARAR s 

### Appendice s Appendi x A - Responsivenes s Summar y Appendi x B - Administrativ e Recor dInde x Appendi x C - Stat e Concurrenc e Lette r Appendi x D - Reference s Cite d

i n

## F . O'CONNO RCOMPAN Y SUPERFUN D SIT E RECOR D O F DECISIO N AMENDMEN T

OPERABLE UNI T 2 Septembe r

200 2 I . SITE NAME , LOCATION , DESCRIPTIO N AN D RATIONAL E FO R AMENDMEN T SIT E NAME : Th e F . O'Conno r Compan y Superfun dSite . SITE LOCATION : Th e F . O'Conno r Superfun dSite i s locate di n Augusta , Main e (Figure 1) . Th e twenty-thre e acre O'Conno r site i s locate do n Easter

n Avenue/Rout e 1 7 i n apredominatel y rural neighborhood . Th e twenty-thre e acr e sit e i s locate dwithi n atwenty-eigh t acr e property owne db y Centra

l Main e Powe r

(CMP) . Th e sit

e i s bordere db y woodland s an dasmal l poultr y far mt o th e north , U.S . Rout e 1 7 t o th e south , privat e propertie s an dresidence s t o th e west , an d th e wes t branc h o f

Rigg s Broo k

an dit s associate dwetland s t o th e east . Publi c wate r ha s bee n provide dt o surroundin g residents , an di s availabl e fo r futur e development . SIT E DESCRIPTION : Th e sit e wa s th e forme r locatio n o f

transforme r

salvagin g processes , whic h include dstrippin g an drecyclin g transformers , som e o f whic h containe dPCB

contaminate doil . Th e F . O'Conno r Compan y operate dfro mth e earl y 1950 s throug h th e lat e 1970s . A s aresult

o f release s o f

polychlorinate dbiphenyl s (PCBs) , lead , chlorinate d polyaromati c hydrocarbon s (cPAHs ) an dvolatil e organi c compound s (VOCs ) at th e site , th e sit

e wa s place do n th e Nationa l Prioritie s Lis t (NPL ) i n 1983 . Principa l feature s o n th e propert y prio r t o remedia l action s include da n Uplan dMarsh , tw o surfac e wate r impoundment s (Uppe r

an d Lowe r Lagoons) , thre e forme r

outdoo r transforme r

wor k area s (TWAs) , an dRigg s Broo k (Figur e 2) . Upo n completio n o f

th e sourc e contro l remedia l actio n fo r

Operabl e Uni t

1 (OU-1 ) th e lagoon s wer e restore da s wetland s an dth e are aencompassin g th e thre e TWA s wa s covere dwit h clea n fill , re-graded , an dsuccessfull y vegetated . I n 1996 , EP A separate dth e sit e int o thre e operabl e units . A s note dabove , OU- 1 addresse dth e sourc e contro l remedial action , OU- 2 addresse s managemen t o f migration , an dOU- 3 addresse s Rigg s Broo k

sediment an dbiota . RATIONAL E FO RAMENDMENT : O n Septembe r 27 , 1989 , EPA , wit h concurrenc e fro mth e Main e Departmen t o f Environmenta l Protectio n (Main e DEP ) an di n accordanc e wit h th e Comprehensiv e Environmenta l Response , Compensatio n an dLiability Ac t (CERCLA) , 4 2 US C § § 960 1 e t

seq. , issue dth e Recor do f Decisio n (ROD ) fo r

th e O'Conno r

site . Th e RO D selected th e remedia

l actio n fo r

th e sit e an destablishe dth e targe t cleanup goal s fo r

soil ,sediments , surfac e water , an dgroundwater . Specifically , th e RO D require dth e remediatio n o f

tw o sit e components :

• Th e sourc e area s tha t were th e TWA s an dsurroundin g soils , sediments , an dsurfac e wate r i n th e tw o lagoon s (late

r designate da s OU-1) ; an d • Sit e groundwate r tha t wa s contaminate dwit h PCBs , benzene , an d1,4-dichlorobenzene , (later designate da s OU-2 ) an dth e Rigg s Broo k sedimen t

an dbiot a(late r

designate da s OU-3) . Thes e tw o components , describe dseparatel y i n th e 198 9 ROD , wer e calle dth e sourc e contro l (SC ) componen t

an dth e managemen t

o f migratio n (MOM) , respectively . Base do n an implementability assessment conducte da s part

o f th e remedial desig n studie s i n th e earl y 1990s , EP A wrot e an Explanatio n o f Significan t

Differenc e (ESD ) i n Jun e 199 4 t o revis e th e sourc e contro l componen t o f th e selecte dremedy . Unde r th e ROD , th e remedia l actio n objectiv e fo r th e groundwate r

(OU-2 ) wa s t o reduc e potentia l futur e publi c healt h risk s fro mingestio n o f PCB , benzene , an d1,4-dichlorobenzene

contaminate dgroundwate r (ROD , pag e 17) . Thi s objectiv e wa s t o b e achieve dusin g a groundwate r

extractio n syste man dan abov e groun dtreatmen t system . I n addition , institutiona l control s were t o b e temporaril y establishe dt o reduc e th e potentia l fo r exposure t o contaminate d groundwate r

an dwere t o remai n i n plac e unti l th e groundwate r remediatio n wa s complete d (ROD , pag e 45) . Th e RO D furthe r specifie dtha t

on e o r mor e pum p test s woul db e conducte da s part o f remedial desig n s o that

an appropriat e groundwate r extractio n syste mcoul db e constructed . I n 1992 , pum p test s wer e carrie dou t a s par t o f th e remedia l design . A s aresul t o f thi s effort , separat e phas e oi l wa s foun di n bedroc k wells , aconditio n no t

previousl y see n a t

th e site . Consequently , MO M effort s focuse do n oi l recover y rathe r tha n groundwate r

extractio n an d treatmen t o f dissolve dcontaminants . Thre e effort s at activ e oi l recover

y usin g vacuum-enhance d pumpin g were carrie dou t betwee n 199 6 an d2001 . I n Apri l 2002 , CM P submitte da n evaluatio n o f th e technica l practicabilit y o f restorin g th e groundwate r a t th e O'Conno r

sit e t o drinkin g wate r qualit y withi n areasonabl e perio do f time . Thi s evaluatio n conclude dtha t becaus e o f

th e geolog y an dhydrolog y a t th e site , ther e wer e n o technologie s whic h coul daccomplis h thi s objective . EP A an dMain e DE P agree dwit h th e conclusio n o f thi s T I evaluation . Thi s RO D Amendmen t

addresse s change s t o th e MO M componen t o f th e origina l 198 9 ROD , followin g th e conclusio n o f th e sourc e contro l remedia l actio n (SCRA ) fo r OU- 1 an dth e T I evaluation . Thfs"RO D amendmen t include s aT I waive r

fo r overburde n an dbedroc k groundwate r

i n asmal l portio n o f

th e twenty-thre e acr e sit e (Figur e 3) . Thi s RO D Amendmen t als o addresse s mino r

changes/clarification s t o th e origina l 198 9 remed y fo r OU-1 , sourc e control , a s modifie db y th e 1994 ES D an d199 5 invocatio n o f th e contingenc y alternative , an dfo r OU-3 , Rigg s Brook .

### Institutional control s i n th e for mo f aDeclaratio n o f

Restrictiv e Covenan

t (Restrictiv e Covenant) hav e been implemente dfo r th e twenty-thre e acr

e sh e t o provid e additional ris k reductio n b y controlling exposur

e t o sit e groundwater

(Figur e 4) . The us e o f

groundwater

beneat h the sit e i s prohibite dwithou t

prio r writte n approva

l b y Main e DEP . Thi s RO D Amendmen t

an dth e document s whic h for mth e basi s fo r th e Amendmen t

are availabl e at

th e followin g informatio n repositories : EP A Record s Cente r 1 Congres s Street , Suit

e 110 0 Boston , M A 02114-202 3 (617)918-145 9 Hours : 1 0 a.m.-noo n 2 p.m.- 5 p.m . Lithgo w Publi c Librar

y 4 5 Winthro p Street Augusta , Main e 04330-554 2 (207)626-241 5 Hours : Tue s - Wed : noo n t o 8 p.m .

Thurs : 8 a.m . t o noo n Fri : 10a.m . t o 6 p.m . 

### Sat : 1 0 

### a.m . t o 3 

### p.m . Main e DE P Ray Buildin g Hospita l Street

Augusta , Main e 0433 3 (207)287-265 1 Hours : (b y appointment ) Mo n - Thurs : 8:3 0 a. mt o 12:3 0 p.m .



### 12:3 0 

### p.m . t o 

### 4:3 0 p.m . Friday : 8:3 0 a.m . t o 12:3 0 p.m . 

### II . SIT E HISTOR Y AN D ENFORCEMEN T ACTIVITIE S Detail s o f th e earlie r sit e histor y an denforcemen t activitie s ar e presente di n th e 198 9 ROD . Th e followin g i s a n updat e t o th e sit e histor y an denforcemen t activitie s whic h hav e occurre dsinc e issuanc e o f

th e ROD . I n Septembe r

1989 , EP A issue daRO D fo r th e O'Conno r

site . Th e bar n structur e wa s t o b edecontaminated , demolished , an dthe n dispose do f offsit e a t appropriate facilities , standin g water an dsediment s i n th e tw o lagoon s wer e to b e removed , soil s contaminate dwit h PCBs , PAHs , an d lea d wer e t o b e excavate dan d treate d usin g solven t extraction , contaminate dgroundwate r wa s t o b e pumpe dfro mth e soil s an dbedrock , treated , an dthe n discharged , an dsediment s an dfis h i n Rigg s Broo k

wer e t o b e sample dfo r

te n years . Performanc e standard s fo r soi l an dsedimen t

wer e se t at 1 pp mPCBs , I pp mcPAHs , an d24 8 pp mlead . Performanc e standard s fo r groundwate r

wer e se t a t 0. 5 pp b PCBs , 5 pp b benzene , an d 2 7 pp b 1,4-dichlorobenzene . Performanc e standard s fo r th e standin g wate r

i n th e lagoon s wer e se t at 0.06 5 pp b PCBs , 1.9 4 pp b lead , an d8 7 pp b aluminum . Performanc e standard s fo r Rigg s Broo k sedimen t

an dbiot awer e se t

a t 1 pp mPCB s an d2 pp mPCBs , respectively . I n Septembe r

1991 , aConsen t

Decre e betwee n EP A an dCM P wa s approve db y th e U.S . Distric t Cour t o f Maine . With thi s Consen t Decree , CM P agree dt o perfor man dfun dth e remed y selecte di n th e 198 9 ROD . On e o f th e component s o f

th e remed y wa s institutiona l control s o n site groundwater . I t

wa s EPA' s inten t

tha t thos e institutiona l control s woul dremai n i n effec t unti l remediatio n o f

th e groundwate r

wa s complete . Th e Consen t

Decre e allowe dfo r

an evaluatio n o f

th e solvent

extractio n technolog y selected fo r th e soils . Followin g thi s evaluation , EP A an dMain e DE P agree dtha t thi s technolog y fo r

th e sit e soil s woul dno t

b e abl e t o attai n th e clean-up goals . A s aresult , i n Jun e 1994 EP A issue dan Explanatio n o f

Significan t

Difference s (ESD ) whic h modifie dth e soi l remedy . Soil s containin g mor e tha n te n part s pe r

millio n (ppm ) PCB s o r

PAH s o r 24 8 pp mlea dwoul db e treate dusin g solven t extractio n technology , an dsoil s containin g betwee n on e t o te n pp mPCB s o r PAH s woul db e consolidate dint o on e are aonsite an dthe n covere dwit h clea n fil l brough t

i n fro m offsite . Thi s designate dare ai s show n o n Figur e 4 . I n Octobe r 1995 , EP A invoke dth e contingenc y remed y se t

fort h i n th e 199 4 ESD . Thi s ES D als o include dacontingenc y tha t allowe dfo r

th e offsit e disposa l o f

soi l an dsedimen t

wit h greate r

tha n te n pp mPCB s an dcPAH s withou t firs t requirin g on-sit e solven t extractio n treatment . A t th e same tim e a s th e ESD , aDeclaratio n o f Restrictiv e Covenan t

wa s execute dbetwee n CM P an dMain e DEP . Thi s Restrictiv e Covenan t i s currentl y i n place . O n Apri l 25 , 1996 , EP A agree dt o dela y completio n o f th e MO M design , an dt o separat e th e Rigg s Broo k

componen t

fro mth e MO M a s athir doperabl e uni t (OU-3) . Thi s wa s don e s o tha t th e samplin g an danalysi s fo r Rigg s Brook , th e remedial actio n require db y th e ROD , coul d begi n prio r

t o th e completio n o f

th e MO M design . Th e S C componen t o f th e selecte dremed y wa s designate da s OU- 1 an dth e MO M componen t wa s designate da s OU- 2 Phas e I o f

th e sourc e contro l remedia l actio n wa s complete di n 1996 . Thi s include dsit e preparation , an dth e decontamination , demolition , an doff-sit e disposal o f th e barn . Phas e I I activities , includin g th e off-sit e disposal o f contaminate dsoi l an dsedimen t an dth e coverin g o f th e designate darea , were complete di n 1997 .

### III . COMMUNIT Y PARTICIPATIO N

Thi s RO D amendmen t

meet s th e criteri afo r

communit

y involvement

specifie di n Section s 300.4 3 5(c)(2)(ii)(A

) through(H ) o f

the NCP . I n Jun e 200 2 EP A publishe daPropose dPla n to amen dth e 198 9 ROD . Th e Propose dPlan fo r OU- 2 calle dfo r

institutiona l control s t o preven t exposur e t o contaminate dgroundwater , activ e recover y o f separat e phas e oi l a s lon g a s practicable , designatio n o f asmal l portio n o f

th e site a s aT I zon e wher e stat e an dfedera l groundwate r standard s woul db e waived , long-termmonitoring , an dfive-yea

r reviews . Th e amende dcleanu p pla n wa s recommende dbecaus e EP A believe di t offere dth e bes t

balanc e amon g th e nin e criteri arequire dt o b e reviewe dunde r th e NCP , includin g th e protectio n o f huma n healt

h an dth e environment

an dth e reductio n o f

contaminatio n throug h treatment . EP A hel dapubli c informatio n meetin g o n Jun e 24 , 200 2 an daforma l publi c hearin g o n Jul y 9 , 2002 . Th e publi c commen t perio dran fro mJun e 1 9 t o Jul y 19 , 2002 . Al l forma l comment s receivedo n th e Jun e 200 2 Propose dPla n are summarize dan dresponde dt o i n th e Responsivenes s Summary , whic h i s include da s Appendi x A o f thi s RO D Amendment . I n addition , comment s receive ddurin g th e publi c informatio n meetin g ar e summarize di n th e Responsivenes s Summary . Pursuan t t o Sectio n 300.825(c ) o f th e NCP , EP A update dth e Administrativ e Recordi n Jun e 200 2 t o ad dth e document s whic h EP A relie do n t o for mth e basi s fo r th e decisio n t o modif

y th e respons e actio n fo r

OU- 2 a t th e O'Conno r

site . Se e Appendi x B fo r th e Administrativ e Index . 

## IV . SCOP E AN

D ROL E O F OPERABL E UNI T Th e O'Conno r

sit e wa s divide dint o thre e operabl e unit s i n 1996 , seve n year s afte r th e RO D wa s signed . Th e thre e unit s ar e a s note dabove , sourc e contro l OU-1 , groundwate r OU-2 , an dRigg s Broo k OU-3 . Remedia l actio n fo r OU- 1 wa s complete di n 199 7 an dEPA , wit h concurrenc e fro mMain e DEP , signe

dof f o n thi s componen

t wit h the approva

l o f the Septembe

r 199 8 Sourc e Contro l Remedial Actio n report (Woodard& Curran , 1998 ) Th e limite dactio n require dfo r Rigg s Broo k

b y th e 198 9 RO D continue s t o b e carrie dout . Thi s RO D amendmen t

pertain s t o OU-2 , althoug h a s describe dbelow , aspect s o f OU- 1 an dOU

3 wer e discusse ddurin g th e developmen t o f th e T I evaluatio n an di t

wa s mutuall y agree db y al l partie s (EPA , Main e DEP , an dCMP ) t o addres s thes e aspect s at th e tim e o f

thi s RO D amendment . Fo r OU-1 , th e 199 4 BS D establishe dtha t aportio n o f

th e sit e woul db e use dt o consolidat e soi l an dsedimen t

containin g level s betwee n on e an dte n pp mo f PCB s and/o r

cPAHs . Thi s designate dare awoul db e covere dwith twelv e inche s o f clea n soil , an dan operatio n an dmaintenanc e plan woul db e develope d to ensure th e integrit y o f thi s component . A s conceptuall y presente di n th e BSD , th e designate dare awa s thre e to fou r acre s bounde do n fiv e side s wit h rounde dturnin g points . A s th e actual excavatio n fo r th e sourc e contro l remedia l actio n evolved , th e boundar y o f

th e designate dare abecam e a25-side dpolygon . A s agreed amon g al l parties , thi s create d adifficul t

situatio n fo r

"anyon e inspectin g th e site t o kno w where th e boundar y was . EP A ha s determine dthat th e followin g change s t o th e designate dare ashal l b e incorporate dint o thi s RO D Amendment : Th e designate dare awil l b e surveyed , th e boundarie s simplifie dt o th e 12-side dshap e show n i n Figur e 4 , an dpermanen t marker s place da t

th e turnin g points . Operatio n an dmaintenanc e fo r OU- 1 shal l includ e th e followin g changes .

• A t fiv e year interval s coinciden t

wit h eac h Fiv e Yea

r Review , composite sample s fro m te n location s randoml y selecte dfro mth e SCR A gri dnode s wil l b e collecte dfro mfou r t o eigh t inche s belo w th e surfac e an danalyze dfo r PCBs .

• I t i s no t necessar y t o resampl e fo r

PAK s base do n th e extensiv e dat acollecte ddurin g th e SCRA . I n al l othe r

aspects , operatio n an dmaintenanc e shal l remai n a s specifie di n th e 199 4 BSD . Regardin g OU-3 , th e 198 9 RO D se t astandar do f

1 pp mPCB s an dcPAH s i n th e Rigg s Broo k sediment s base di n part

o n inpu t fro mU S Fis h & Wildlif

e Servic e (USFWS) . However , i t wa s agree db y al l parties , includin g USFWS , tha t th e negativ e short-ter mimpact s t o th e wetland s ecolog y outweighe dth e remova l o f sediment s t o tha t

level . A trigger

leve l o f 5 pp mPCB s fo r furthe r actio n wa s therefor e establishe dA s state di n th e 198 9 ROD , "i f a n increas e i n th e curren t PC B sedimen t

level s occur s abov e th e 5 pp mthreshol dand/o r th e fis h tissu e sample s ar e foun dt o b e greate r

tha n 2 ppm , the n amor e rigorou s samplin g effor t o f suc h contaminatio n wil l b e conducte dt o determin e th e nee dfo r and/o r exten t o f furthe r remedia l action s t o b e undertake n withi n Rigg s Brook , i f

any. " (ROD , pag e 47 ) Thi s i n fac t occurre di n 199 7 whe n soi l an d sedimen t abov e 5 pp mPCB s were remove dsimultaneousl y wit h th e ongoin g SCRA , an dagai n i n 199 9 an d200 0 whe n additiona l sample s were collected . Th e mos t recen t dat a(2001 ) showe d tha t 3 5 o f 3 6 sampl e location s wer e belo w th e 5 pp mtrigge r level , an dth e majorit y o f th e sample s wer e non-detect . Main e DE P requeste dtha t thi s RO D amendmen t

restat e tha t

th e targe t cleanu p goa l fo r

Rigg s Broo k

sedimen t remain s a t

1 pp mPCB s an dcPAHs . Th e result s fro mtw o biot asamplin g event s (199 7 an d2000) , demonstrat e tha t concentration s o f PCB s detecte di n biot ahav e no t exceede dth e RO D targe t leve l o f 2 ppm , an di n fac t

hav e al l bee n belo w 1 ppm . 

### V . DESCRIPTIO N O F CHANGE S T O TH E 198 9 RO D 1 . DESCRIPTIO N OF1989 REMED Y

### Th e remedy selecte db y th e 198 9 RO D wa s develope dto satisf y th e followin g fiv e remedia l actio n objective s (RAO) : •reduc e publi c healt

h an denvironmental risk s fro mdirec t contac t wit h contaminate d soils , •reduc e publi c health risk s fro minhalation s o f PC B vapors , •reduc e futur e healt

h risk s fro mingestio n o f

contaminatedgroun dwate r foun do n th e site ,

• reduc e publi c healt

h risk s fro mingestio n o f

PCB-contaminate dfis h fro mRigg s Brook , an d



### • reduc e risk s t o aquati c an dterrestrial wildlif e fro mexposure t o contaminate dsediments . Th e firs t tw o RA O were achieve dwit h th e completio n o f

th e sourc e contro l remedia l actio n i n 1997 . Th e soi l clean-u p bega n i n 199 6 with th e cleaning , demolition , an doff-sit e disposa l o f th e barn situate dalon g Rout e 17 , an dother site preparatio n activities . Th e secon dphas e o f th e soi l cleanu p wa s complete di n 1997 . Thes e activitie s include dth e collectio n an doff-sit e disposa l o f lagoo n water , an dth e excavatio n an doff-sit e disposa l o f nearl y 20,000 ton s o f

soil . A n additiona l 300 0 t o 400 0 ton s o f soil s with PCB s o r

PAH s concentration s betwee n 1 an d1 0 pp m wer e place dwithi n th e designate dare aonsite . Thi s are awa s the n coveredwit h aminimu mo f on e foot o f clea n fil l brough t

i n fro moffsite . Th e entir e site wa s the n graded . Drainag e pattern s an dth e on-sit

e wetland s were restored . A n additiona l 0. 4 acre o f wetland s wa s create di n th e forme r lagoon s a s replacemen t

fo r wetland s los t

a s aresul t

o f th e clean-up activities . Laborator y test s o f

sample s collecte dfro mth e botto man dperimete r o f th e excavatio n demonstrate dtha t

th e excavatio n ha dremove dth e contaminate dsoi l t o th e performanc e standard s se t

i n th e 1994 BSD . Combine dwit h th e operatio n an dmaintenanc e o f th e soi l cove r an dmonitorin g points , th e ris k t o publi c healt

h fro mcontac t

with th e soi l an dinhalatio n o f vapor s ar e addressed . A mor e complet e descriptio n o f th e sourc e contro l activitie s ca n b e foun di n th e Septembe r 199 8 SCR A report . Th e las t tw o RA O hav e bee n achieve dthroug h th e monitorin g o f sediments , analysi s offis h tissu e fo r PC B accumulation , an dth e 199 7 excavatio n o f sedimen t i n thre e separat e location s wher e concentration s exceede dth e trigge r level . A mor e complet e descriptio n o f th e wetland s restoration , ho t spo t excavations , an dRigg s Broo k monitorin g ca n b e foun di n th e Wetland s Constructio n Monitorin g report s fo r 1997-200 0 (Th eTh e groundwate r remedy selecte d i n th e 198 9 RO D include dpumpin g wells , atreatmen t system , an danetwor

k o f monitorin g well s to trac k contaminatio n levels . Th e intent wa s to pum p an d the n trea t groundwater

whic h containe ddissolve dPCB s an dVOC s an dthereb y restor e th e quality o f th e groundwater . I n 1992 , abedroc k

pum p tes t

wa s performed . Durin g th e tes t aseparat e phas e oi l laye r u p t o thre e an dhal f

fee t thic k wa s pulle dint o thre e bedroc k well s i n Transforme r

Work Are aI I (TW A I I - se e Figur e 2) . Thi s wa s th e firs t tim e tha t separat e phas e oi l ha dbee n detecte di n th e bedrock . A s aresult , additiona l monitorin g well s wer e installe dt o determin e ho w far th e oi l extended . N o additiona l oi l wa s discovere dan di t wa s conclude dtha t

th e exten t

o f fre e oi l i n th e bedroc k wa s limited . Th e nex t stag e o f th e groundwate r

remed y too k

plac e i n 1996-97 . Abou t 2 8 gallon s o f

PCB

lade n oi l were pumpe dou t o f th e shallo w bedroc k

durin g thi s period . Th e pumpin g syste mwa s shu t dow n whe n oi l wa s n o longe r recovered . Fro m199 7 t o 2001 , CM P continue dt o recove r oi l fro mwell s b y usin g absorben t material s t o remov e an y oi l whic h accumulate di n th e wells . A littl e unde r seve n gallon s o f

PCB-lade n oi l wa s recovere ddurin g thi s perio dfro mwell s i n TW A II . A thir deffor t

at oi l recover

y too k plac e fro mAugus t

t o Octobe r

2001 . Fiv e well s i n TW A I I wer e alternatel y pumped . Jus t unde r 2 0 gallon s o f

PCB-lade n oi l wer e recovered . Thi s pumpin g effor t wa s als o shu t

dow n whe n oi l wa s n o longe r pulle dint o th e system . 2 . CHANGE S T O THE 1989 REMED Y I n Apri l 2002 , CM P submitte da n evaluatio n o f th e technical practicabilit y o f restorin g th e groundwate r

a t th e O'Conno r

sit e t o drinkin g wate r

qualit y withi n areasonabl e perio do f tim e Thi s evaluatio n conclude dtha t becaus e o f

th e geolog y an dhydrolog y a t th e site , ther e wer e n o technologie s whic h coul daccomplis h thi s objectiv e (th e thir dRA O i n th e 198 9 ROD) . Th e evaluatio n wa s resubmitte di n Jun e 200 2 followin g EP A an dMain e DE P comments . EPA , with concurrenc e fro mMain e DEP , approve dth e Jun e 200 2 report . Thi s RO D amendmen t

fo r OU- 2 select s aremed y consistin g o f institutiona l controls , activ e oi l recovery , long-ter mmonitorin g o f groundwater , an dfive-year reviews . Thi s RO D amendmen t recognize s th e technica

l impracticability o f

achievin g th e thirdRA O (reductio n o f futur e health risk s fro mingestio n o f

contaminate dgroundwate r foun do n th e site ) withi n areasonabl e tim e frame . I t establishe s atechnica l impracticabilit y zon e fo r aportio n o f

th e sit e wher e stat e an d federa l drinkin g wate r

standard s ar e waived . A compariso n o f

th e original 198 9 remed y fo r groundwate r

an dth e modifie dremed y fo r OU- 2 i s provide di n Tabl e 1 .

### VI . SUMMARY O F SIT E CHARACTERISTIC S Thi s section o f

th e repor t provide s asummar

y o f th e groundwater

dat aa t th e site , startin g fro m th e upgradien t

positio n a

t MW-101A/B , throug h th e uplan dmars h area , th e T I zon e (TW A I I an d VER) , th e are adowngradient o f th e TI zon e (MO

M wells) , an dt

o th e groundwate r

discharg e are arepresente db y MW-106A/B . Se e figur e 3 for monitorin g well locations . Groundwate r

cleanup standard s establishe di n th e RO D includ e tota l PCB s at 0. 5 //g/L , benzen e a t 5 Aig/ L an d1,4-dichlorobenzene a t 2 7 /ug/L . I n addition , basedo n th e ARAR s revie w discusse di n Sectio n VIII . 1 o f thi s RO D amendment , fiv e othe r VOC s were identifie dwhic h sinc e th e 198 9 RO D hav e ha dARAR s establishe dan dfo r whic h a.T I Waive r

wil l apply . Thes e ARAR s includ e Maximu mContaminant s Level s (MCLs ) an dMain e Maximu mExposur e Guideline s (MEGs ) fo r

eigh t VOC s an dPCBs . Fo r

eac h o f thes e fiv e compounds , th e ME G i s eithe r th e sam e o r lowe r tha n th e respectiv e MCL . 1 . Upgradient

Locatio n Monitorin g well s MW-101 A an dMW-101 B are upgradien t o f th e TWAs , locate dnea

r th e western boundary o f

th e site i n a n uplan darea . Thes e well s wer e installe ddurin g th e R I t o provid e a n indicatio n o f

regiona l water qualit y a s groundwater

flow s easterly beneat

h th e site towar dRigg s Brook . MW-10 1 A monitor s groundwate r i n th e overburde n soi l an dMW-101 B monitor s th e bedroc k

groundwater . Annual samplin g o f thes e well s sinc e 199 6 ha s no t detecte d any PCB s or

VOCs . 2 . Uplan dMars h Are a A n investigatio n t o determin e th e presenc e an dextent o f oi l i n th e desiccate dcla

y i n th e Uplan d Mars h are awa s complete di n 199 8 an d1999 . Th e inten t o f th e investigatio n wa s t o determin e th e likel y sourc e o f

oi l tha t accumulate di n awetlan dpiezomete r (UM-1 ) i n th e Uplan dMars h an dt o determin e th e distributio n o f an y additiona l residua l oi l i n tha t area . Th e investigatio n involve d completin g 1 9 GeoProb e boring s wit h continuou s samplin g (figur e 11) . Th e sample s wer e retrieve dan dlogge dwit

h respec t t o th e soi

l typ e an dteste dfo r

oil . Base do n th e GeoProb e borings , th e soi l stratigraph y an dexten t o f residua l oi l wa s determine di n th e Uplan dMarsh . Th e brow n desiccate dcla y ha s ablock y fractur e structur e wher e oi l reside s i n bot h vertica l an d horizonta l fractures . A slight t o moderat e oi l shee n wa s foun dcomin g fro mdiscret e fracture s i n th e clay . Al l oi l foun dresideda s aresidua l coatin g o n th e cla

y fracture s walls . Th e result s o f th e analysi s indicate dtha t

PCB s i n soil s aroun dan dincludin g th e fracture s wer e foun dt o rang e fro m non-detec t

(ND ) t o 100 0 //g/k g (i.e . fro mN D t o 1 ppm) . Th e RO D targe t leve l fo r PCB s i n th e overal l mas s o f

soi l outsid e th e Sourc e Contro l Designate dArea , specifie ddurin g th e sourc e contro l remedia l action , i s 1 ppm . Therefore , concentration s o f PCB s foun di n thes e sample s di d no t exceedth e targe t

level .Th e dat acollecte dsugges t tha t th e oil , whic h originate dfro mTW A I I durin g transforme r salvaging operations , ra

n of f th e lan dsurfac e toward th e Uplan dMars h an dinfiltrate dint o th e uppe r brow n desiccated cla

y durin g th e tim

e tha t th e sit e wa s active . Unabl e to mov e downward , both fro mth e underlyin g sof t cla y an dth e lac k

o f th e entranc e pressure s necessar y fo r a n immiscibl e liqui dt o overcom e surfac e tensio n forces , th e oi l ha s remaine drelativel y immobil e i n th e uppe r

cla y fractures . I n th e northern portio n o f th e study area , wher e th e desiccate d clay i s i n direc t contac t with th e till , ther e i s n o evidenc e tha t suggest s th e oi l ha s migrate dalon g th e till/bedroc k

interface . I t

appear s tha t

th e oi l ha s migrate dverticall y downwar dint o th e clay reachin g a n equilibriu mbetwee n surfac e tensio n force s impose db y th e clay fractur e capillaries , th e densit y consideration s o f a n immiscibl e liqui di n asaturate dmediu man dauni t infiltratio n gradient . Very littl e horizonta l movemen t ha s occurre da t

dept h becaus e th e horizonta l gradien t acros s th e sit e i s no t

grea t enoug h t o overcom e th e resistin g force s describe dabove . I t i s believe dtha t

th e oi l foun di n th e are asurroundin g UM- 1 i s residua l i n natur e an dwithou t a significan t

gradien t doe s no t migrate . 3 . TI Zon e Well s A . PCB s Dat aEvaluatio n Th e groundwate r

fro mth e fiv e well s i n th e TW A I I Are awa s no t sample di n 199 6 o r

199 7 becaus e oi l wa s foun di n thes e well s an di t wa s agree dtha t

th e well s woul dno t

giv e representativ e result s o f th e dissolve dconcentrations . Afte r 1997 , th e fou r

groundwate r observatio n well s (OW-202B , OW-204B , OW-301B , an dOW-302B ) an dth e VE Rextractio n wel l (RW-101 ) wer e sample dquarterl y fo r PCB s an dth e seve n targe t VO C compound s i f

oi l wa s no t detecte d i n th e wells . However , th e result s o f TW A I I wel l samplin g indicate dawid e variatio n i n contaminant concentrations . I t

wa s determine dtha t

thi s wa s du e t o th e presenc e o f emulsifie doi l i n th e wel l wate r an dassociate dVOC s i n an oi l emulsio n whic h wa s no t presen t sufficientl y t o b e measure db y th e interfac e probe , bu t wa s visually detecte di n th e sample s an d purg e water . Th e sample s take n wer e no t representativ e o f

actua l dissolve dcontaminant s i n th e groundwater . Tabl e 2 give s th e result s o f PC B dat acollecte dfro mTW A I I fro m199 8 t o 2001 . Th e result s i n bol dprin t

ar e abov e th e RO D cleanu p goal fo r PCB s o f 0. 5 /zg/ L an drepresen t

th e impac t

o f oi l emulsion s i n th e samples , no t dissolve dPCB s i n groundwater . Tabl e 2 indicate s tha t

tw o wells , OW-301 B an dOW-302 B continuall y ha dPCB s detecte da t greate r concentration s tha n th e RO D cleanu p standar do f 0. 5 /zg/L . Thes e ar e th e same tw o well s tha t ha dgroundwate r

tha t regularl y exceede dth e VO C cleanu p standards . Separat e phas e oi l ha s bee n observe di n thre e othe r TW A I I wells , OW-202B , OW-204B , an dth e VE Rextractio n well , RW-101 , o n a n ongoin g basi s sinc e Septembe r 1998 . PCB s wer e detecte dat

8,90 0 /zg/

L at OW-302 B i n December 1998 . I n Apri l 2001 , th e concentratio n o f

PCB s at OW-302 B wa s 4 4 pg/L . Th e PC B result s at OW-302 B hav e range d 

### 1 0

### fro m2. 5 t o 8,900//g/L . Separat

e phas e oi l ha s als o bee

n observedi n thi s wel

l ove r time . In November

2001 , 1.2 5 fee t

o f oi l wa s measured . Th e increase dthicknes s o f oi l i n OW-302 B i n Novembe r 200 1 i s mos t

likel y the result

o f the operatio n o f

the VERsyste

m(Phas e III ) i n Septembe r 200 1 an dextremely lo w wate r tabl e elevation . The observe doi l i s likely responsibl e fo r th e PC B concentration s detecte da t OW-302B . Th e histori c PC B result s report ca n b e foun di n th e Jun e 200 2 Technical Impracticabilit y Evaluatio n Report , Appendi x C . B . VO C Dat aEvaluatio n Th e RO D cleanup goal s are 5 //g/ L fo r benzene an d2 7 ^g/

L fo r 1,4-dichlorobenzene . Additional ARAR s fo r

whic h aT I waiver

will appl y are liste di n Tabl e 3 . Benzen e concentration s fro mth e groundwate r i n TWA I I well s range dfro m0 t o 8. 0 //g/ L betwee n 199 8 an d2001 . Benzen e concentration s fro mOW-302 B wer e regularl y (6/98 , 9/98 , 12/98 , an d6/99 ) detecte da t 6. 0 //g/L , whic h i s 1 ^g/

L ove r th e MCL/MEG . Th e las t samplin g event at thi s well detecte dbenzen e at 8. 0 ftgf L i n Apri l 2001 . N o other TW A I I well s exhibite d a n exceedanc e o f

th e benzen e MCL/MEG . Th e Main e ME G fo r

1 , 4-dichlorobenzen e (2 7 //g/L ) wa s regularl y exceede da t both OW-301 B an dOW-302 B between 199 8 an d2001 . Th e 1,4-dichlorobenzen e result s a t thes e tw o well s range dfro m89-720 //g/L . Severa l other targe t VOC s wer

e als o detecte di n OW-301 B an dOW

302B . Th e tw o TW A I I well s wit h th e exceedanc e fo r

VOC s are locate dclos e togethe r i n th e cente r o f TWA II . Thes e tw o well s ar e locate dimmediatel y adjacen t to wel l OW-202B , whic h wa s use dfor

th e 199 2 pumpin g tes t

an di s responsible for

drawin g oi l int o th e bedrock aquifer . 1,4-dichlorobenzen e wa s als o detecte di n lo w concentration s (belo w th e MEG ) i n observatio n well s OW-204 B (u p t o 0. 7 //g/L) , OW-202 B (u p t o 2 0 //g/L ) an dth e VE Rwel l RW-10 1 (u p t o B/.g/L) . Th e T I evaluatio n o f

ARAR s identifie dMCLs/MEG s fo r fiv e othe r VOC s whic h hav e bee n detecte di n th e groundwater . I n addition , anothe r VOC , 1,2,3-trichlorobenzene , ha s bee n detecte dbu t

doe s no t hav e eithe r

an MC L o r

MEG . Thre e o f

thes e VOCs , chlorobenzene , 1,2

- dichlorobenzene , an d1,2,4-trichlorobenzene , wer e detecte di n th e R I sampling . Fiv e o f thes e othe r VOC s were detecte di n th e TW A I I well s betwee n 199 8 an d2001 . Concentration s o f chlorobenzen e range dfro m4 t o 24 0 //g/ L at OW-301 B an dOW-302B , exceedin g th e Main e ME G o f 4 7 /zg/L . 1,2-Dichlorobenzene an d1,3-Dichlorobenzene (ME ME G o f 8 5 //g/L ) were detecte da t

OW-301 B an dOW-302 B a t concentration s rangin g fro m3-21 0 //g/ L an d2-16 0 //g/L , respectively . Thes e compound s wer e detecte da t relativel y lo w concentration s a t th e othe r TW A I I wells . Concentration s o f

1,2,4-trichlorobenzen e hav e bee n detecte dabov e th e Main e ME G o f 7 0 A*g/ L a t OW-202B an dOW-301 B a t concentration s rangin g fro m3-61 0 Mg/L , an drangin g a s hig h a s

1 1320 0 ^g/ L a t OW-302B . Th e histori c VO C result s are include di n th e Jun e 200 2 Technica l Impracticabilit

y Evaluatio n Report , Appendi x D . C . VE ROperatio n Th e vacuum-enhance drecovery syste m(VER ) ha s bee n operate dfo r thre e period s o f

tim e followin g post-RO D pilo t tests . Th e tota l amoun t

o f oi l recovere dfro mth e fiv e TW A I I well s sinc e thei r

installatio n i s approximatel y 85. 2 gallons . A summar y o f oi l recovere dfro mth e TW A I I well s i s presente di n Tabl e 4 . Fiv e well s (OW-202B , OW-204B , OW-301B , OW-302 B an dRW-101 ) i n th e forme r TW A I I Are aan dpiezomete r

UM- 1 hav e bee n monitore dfo r groundwate r

elevatio n an doi l thicknes s o n amonthl y basi s sinc e 1998 . Wheneve r oi l wa s detecte di n awell , an absorben t soc k wa s lowere d int o th e well t o adsor

b an dremov e th e oil . Sinc e th e las t oi l recover

y effor t i n th e fal l 2001 , 1 .2 5 fee t o f oi l accumulate di n OW-302 B an dwa s remove dusin g absorben t socks . 4 . Managemen t

o f Migratio n A . PC B Dat aEvaluatio n Include di n thi s sectio n i s adiscussio n o f thos e well s whic h ar e locate di n th e are adowngradien t o f th e T I zone . Asid e fro mafe w initial samplin g event s (prio r t o 1994 ) wher e elevate d concentration s o f

PCB s ma

y hav e resulte dfro mPC B adsorptio n ont o soi l particle s i n th e groundwate r

samples , concentration s o f PCB s i n groundwate r

sample s collecte dfro mwell s outsid e o f

th e TW A I I Are ahav e no t exceede dth e 198 9 RO D targe t cleanu p leve l fo r

PCB s (0. 5 I n Marc h 1999 , th e groundwate r sample s fro msi x MO M monitorin g well s wer e analyze dusin g USEP A Modifie dMetho d68 0 fo r tota l homologu e PCBs . Th e result s o f th e 68 0 analyse s ar e summarize di n Tabl e 5 . Concentration s o f PCB s wer e belo w th e RO D targe t cleanu p level . A s state di n Sectio n VIII . 1 . , curren t ARAR s hav e bee n reviewe dan dconcentration s o f PCB s a t several well s ar e a t

o r slightl y abov e th e 1 99 2 Main e ME G o f 0.0 5 /^g/L . Futur e analysi s o f groundwate r

fro mMO M well s wil l b e don e usin g alowe r detectio n limit , t o determin e i f groundwate r

outsid e th e T I Zon e (se e Figur e 3 ) meet s th e 199 2 Main e ME G o f 0.0 5 Mg/L . B . VO C Dat aEvaluatio n Thi s sectio n wil l discus s th e VO C result s compare dt o federa l MCL s an dMain e MEG s (se e Figur e 2 fo r

wel l locations) . Th e VO C result s fro mMW-104 B an dOW-201 B indicat e th e presenc e o f lo w t o moderat e level s 1 2

### o f

VOC s in the bedrock

a t thes e locations . The ME G for 1,4-dichlorobenzen

e (2 7 //g/L ) ha s been exceededa

t bot h wells . Prio r

to Jun e 1998 , th e concentratio n o f 1,4-dichlorobenzen e range dfro m26-9 1 /zg/

L i n MW-104B an d25-5 5 /zg/ L i n MW-201B . Sinc e then , the concentratio n o f

1,4-dichlorobenzen

e ha s bee n consistentl

y between 20-40 //g/

L in MW-104 B an d20-3 6 //g/

L i n MW-201B . Thes e ar e reduction s an di f

thes e decreasing trend s continue , th e concentration s o f

1,4-dichlorobenzene a

t OW-201 B an dMW-104 B ar e expecte dto b e consistently belo w th e ME G i n th e nea r future . Fo r th e VOC s with post-RO D MCLs/MEGs , 1,2-dichlorobenzen e exceede dth e ME G o f 8 5 //g/ 1 at thes e well s prio r

t o 1997 , bu t

ha s bee n belo w th e ME G since , an d1,3-dichlorobenzen e ha s no t exceede dit s ME G o f

85//g/L . Concentration s o f benzene , chlorobenzene , 1,2, 3 - trichlorobenzen e an d1,2,4-trichlorobenzen e hav e been ver y lo w to moderat e an dhav e no t exceede dMEG s a

t MW-104 B an dOW-201B , excep t fo r 1,2,4-trichlorobenzen e prio r to 1995 . Result s o f

analysi s o f

groundwater

fro mmonitorin g well s MW-507 A an dMW-508B , place di n th e bedroc k

trough , indicate th e presenc e o f fiv e VOC s i n MW-507 A an dfou r VOC s i n MW

508B . Th e relativ e VO C concentration s are generall y higher i n th e shallo w groundwate r monitore db y MW-507A . Monitorin g well MW-507 A i s locate di n abedroc k troug h an d screene di n th e till/bedroc k surfac e specificall y t o monito r VO C concentration s i n th e primary migratio n pathwa y where contaminate dgroundwate r fro mth e forme r

TW A sourc e area s flow s slowly i n asoutheasterl y direction . Monitorin g wel l MW-508 B wa s installe dint o th e bedroc k t o monito r VO C concentration s i n th e secondar y bedroc k migratio n pathway . Th e concentration s o f 1,4-dichlorobenzen e i n MW-507 A range dfro mND-8 1 //g/ L i n th e pas t

fiv e years . Th e concentration s o f

1,4-dichlorobenzen e a

t MW-503 , downgradient

o f MW-507A , are muc h lowe r (ND- 8 /^g/L ) than a

t MW-507A . The sam

e decreas e i n concentration s wa s observe dfor 1,2-dichlorobenzen e an d1,3-dichlorobenzene . Thi s reductio n i n VO C concentration s betwee n MW-507 A an dMW-502/MW-50 3 indicate s tha t very littl e contaminan t

mas s i s flowin g pas t

th e bedroc k troug h area . Concentration s o f benzene , chlorobenzene , 1,2,3-trichlorobenzen e an d 1,2,4-trichlorobenzen e wer e detecte da t lo w concentration s i n al l fou r well s MW-507A , MW

508B , MW-50 2 an dMW-503 . I n addition , concentration s o f VOC s at MW-50 1 (downgradien t

o f TW A III ) an dMW-511 A (downgradien t

o f TW A I ) hav e bee n no n detec t t o trac e levels . Base do n thi s evaluatio n o f VO C data , well s alop g th e boundar y o f th e T I zon e ar e i n attainmen t o f federa l MCL s an dMain e MEG s (MW.501 , MW-502 , MW-50 3 an dMW-5 1 OA) . Thes e decreasin g trend s i n VO C concentration s ar e likel y du e t o th e successfu l completio n o f th e SCR A an dremova l o f

residua l oi l with th e VE Rsystem , an dar e expecte dt o continue . C . Discharg e Zone , MW-106A/ B Concentration s o f

PCB s i n groundwater

sample s collectedfro mMW-106A/ B hav e no t

exceede d 1 3th e RO D targe t cleanup leve l fo r

PCB s (0. 5 Th e VO C concentration s fro mth e groundwater i n MW-106 A an dMW-106 B hav e been relatively consisten

t ove r th e pas t si x years . MW-106 A monitor s th e overburde n aquife r a t thi s locatio n an dflow s unde r lo w artesia

n condition s durin g period s o f hig h groundwater . Non

detec t t o trac e concentration s o f th e seve n VOC s hav e bee n detected . Th e deeper wel l (MW

106B) , flow s unde r

artesian condition s mos t o f th e year , an di s believe dt o b e interceptin g a portio n o f

th e bedroc k

groundwate r

migratin g fro mth e sit e an drepresent s th e bedroc k wate r quality . Lo w level s o f

si x VO C compound s ar e regularl y detecte dat MW-106B . Th e concentration s o f

1,2,3-Trichlorobenzen e an d1,2,4-Trichlorobenzen e hav e generall y bee n decreasin g at

MW-106 B sinc e Marc h 199 7 an dMarc h 1995 , respectively , wit h mor e significan t decrease s i n 200 0 an d2001 . Th e 1,2,4-trichlorobenzen e concentration s are wel l belo w th e MC L an d199 2 ME G o f 7 0 yUg/L . (Ther e i s n o MC L o r

ME G fo r 1,2,3-trichlorobenzene . However , i t can b e generall y assume d that it s ris k factor s woul db e simila

r t o 1,2,4-trichlorobenzene , an dth e detecte dconcentration s o f 1,2,3-trichlorobenzen e are als o wel l belo w 7 0 //g/L. ) Histori c PCB s an dVOC s result s o f th e MO M monitorin g conducte dbetwee n Octobe r 199 5 an d Septembe r

200 1 an dprio r

analytica l result s ar e include di n th e Jun e 200 2 Technica l Impracticability Evaluatio n report , Appendice s G an dH . 

### VII . SUMMAR Y O F SITE RISK S Huma n healt

h an denvironmental ris k assessment s wer

e conducte da s par t

o f th e Feasibility Stud y leadin g u p t o th e 198 9 Recordo f Decision . Thes e assessment s identifie dseve n exposur e scenario s a s posin g curren t an dpotentia l futur e risk s t o huma n healt h o r th e environment . (ROD . pag e 13 ) O f

thes e seven , fiv e wer e associate dwit h th e soil s an dlagoo n sediments , on e wit h ingestio n offis h fro mRigg s Brook , an don e with ingestio n o f groundwate r

fro mth e bedrock :

• direc t

contac t wit h soil s b y children ;

• inhalatio n o f

vapor s fro msurfac e soils , • ingestio n offis h caught i n Rigg s Brook , • futur e direc t

contac t wit h soil s b y on-sit e inhabitant s

• futur e direc t

contac t wit h sediment s i n th e lowe r lagoo n b y children , an d

• futur e inhalatio n o f vapor s b y on-sit e inhabitants ; and , • futur e ingestio n o f groundwate r

fro mwithi n th e bedrock . 

### 1 4

### Followin g th e completio n o f th e SCRA , onl y tw o potential exposur e scenario s remain . They ar e futur e ingestio n o f

groundwate r

fro mwithi n th e bedrock , an dingestio n offis h caught i n Rigg s Brook . A site-wid

e five-yea r review wa s performe di n 2002 for al l thre e operable units . Th e exposur e assumptions , toxicit

y data , an dcleanu

p level s fo r

groundwate r

wer e evaluate da s part

o f th e overal l protectivenes s determination . Th e revie w di dno t identif y an y change s i n th e exposure assumptions , foun dth e toxicit y dat ahav e ha donl y minima l change s (some slightl y increasing , other s decreasing ) an dconclude dthat there ha dbee n n o significant chang e i n site risks . (EPA , 2002 ) Sinc e th e 198 9 ROD , th e Stat e o f Main e ha s promulgate db y referenc e th e 199 2 MEGs . Th e 199 2 ME G fo r

PCB s i s 0.0 5 ppb , an orde r o f magnitud e lower

tha n th e MC L o f

0. 5 ppb , whic h i s th e RO D standard . Excep t fo r th e immediat e are asurroundin g an dincludin g TW A II , PC B concentration s i n th e groundwate r wer e clos e t o thi s standard(0.0 2 t o 0.0 9 pp b i n th e on e samplin g even

t where alowe

r detectio n limit

wa s reached) . Th e Restrictiv e Covenan t currentl y ensure s tha t

ther e wil l b e n o exposure t o th e groundwate r beneat h th e site . 

### VIII . TECHNICA L IMPRACTICABILIT Y DETERMINATIO N Th e continue dpresenc e o f separate phas e PCB-lade n oi l fou r year s afte r

th e successfu l completio n o f

th e sourc e contro l remedial actio n suggeste drestoratio n o f th e groundwate r

usin g th e VE Ro r

agroundwate r

extractio n an dtreatmen t

systemi s no t

possible . Consequently , EPA , wit h concurrenc e fro mMain e DEP , agree dt o aproposal b y CM P t o evaluate whether i t woul d b e technicall y practicabl e t o restor e contaminate dgroundwate r t o drinkin g wate r

standards , includin g MCL s an dMEGs . Restoratio n o f

contaminate dgrouudwate r i s on e o f th e primary objective s o f

th e Superfun d program . Th e NC P state s that "EP A expect s t o retur n usabl e groun dwater s t o thei r beneficia l use s whereve r

practicable , withi n atim e fram e tha t i s reasonabl e given th e particula r circumstance s o f

th e site. " Sectio n 300.430(a)(l)(iii)(F ) o f th e NCP . Generally , restoratio n cleanu p level s i n th e Superfun dprogra mar e establishe db y applicabl e o r relevan t an dappropriat e requirement s (ARARs) , suc h a s th e us e o f federal o r state standard s fo r

drinkin g water

quality . Further , unde r

CERCLA , a n alternativ e selecte dt o addres s contaminatio n at asite mus t

achiev e th e ARAR s identifie dfo r

th e action , o r

provid e th e basi s fo r

waivin g th e ARARs . ARAR s ma y b e waive dfo r

an y o f si x reasons , includin g wher e complianc e wit h th e requiremen t i s technicall y impracticabl e fro ma

n engineerin g perspective . Se e Sectio n 121(d)(4 ) o f CERCL A an dSectio n 300.430(f)(l)(ii)(C ) o f

th e NCP . Th e primary consideration s fo r determinin g th e technical impracticability (TI ) o f

achievin g ARAR s are engineerin g feasibilit y an dreliability . Se e NC P Preamble , 5 5 Fed . Reg . 874 8 (Marc h 8 , 1990) . EPA' s Guidance fo r

Evaluatin g th e Technica

l Impracticabilit y o f

Ground-Wate r

Restoration . (OSWE RDir . 9234.2-25 , Septembe r 1993 , Interi mFinal ) specifie s th e followin g component s a s necessar y fo r aT I evaluation : 1 51 . Specifi c ARAR s o r medi astandar dfo r

whic h T I determination s are sought , 2 . Spatia

l are aove

r whic h th e TI decisio n wil l apply ; 3 . Conceptua

l mode l that

describe s sit

e geology , hydrogeology , groundwate r contaminatio n sources , fat e an dtransport ; 4 . A n evaluatio n o f

th e restoratio n potential , includin g predictiv e analyse s o f th e timeframe s t o attai n require dcleanu p level s an dademonstratio n tha t n o othe r remedia l technologie s coul db e capabl e o f

achievin g groundwate r

restoration ; an d 5 . Cos t

estimate s o f

th e propose dremed y options . Followin g aT I evaluation , EPA' s goa l o f restorin g contaminate dgroundwate r within a reasonabl e tim e fram e will b e modifie dwher e restoratio n i s foun dt o b e technicall y impracticable . I n suc h cases , EP A wil l selec t an alternativ e remedia l strateg y tha t i s technicall y practicable , protectiv e o f huma n healt

h an dth e environment , an dsatisfie s th e requirement s o f CERCLA an dth e NCP . Where groundwate r ARAR s ar e waive dat

aSuperfun dsite du e t o technica l impracticability , EPA' s general expectation s ar e t o preven t furthe r migratio n o f

th e contaminate dgroundwate r plume , preven t

exposur e t o th e contaminate dgroundwater , an d evaluat e furthe r

ris k reductio n measure s a s appropriate . Se e Sectio n 300.430(a)(l)(iii)(F ) o f th e NCP . Thes e expectation s shoul db e evaluate dalon g with th e nin e remed y selectio n criteri a provide di n th e NCP . Th e result s o f

th e T I Evaluatio n fo r

O'Conno r

ar e provide dbelow . 1 . ARAR s Unde r th e EP A Groundwate r

Protectio n Strategy , EP A ha s classifie dth e aquife r beneat h th e sit e a s aClas s I I aquifer , i.e. , groundwate r whic h potentiall y coul db e asourc e fo r drinkin g wate r

i n th e future . Thus , Maximu mContaminan t Level s (MCLs) , an dnon-zer o Maximu mContaminan t Leve l Goal s (MCLGs) , establishe dunde r th e Saf e Drinkin g wate r

Act , ar e ARARs . Th e state Maximu mExposure Guideline s (MEGs ) are chemical-specifi c ARAR s that are health

base dguideline s intende dt o determin e drinkin g wate r qualit y fo r

privat e residentia l wells . MEG s ar e relevan t

an dappropriat e requirement s i n establishin g groundwate r remediatio n goal s Th e MCL s an dMEG s fo r whic h atechnica l impracticabilit y waive r wil l appl y ar e a s follows :

1 6Tabl e 3 : Chemical-Specifi c ARAR s fo r T I Waive r I ! contaminant I I O f Concer n I IBenzen e



### 1,4

- 200 1 Maxunu m

Groundwate r Concentratio n (//g/L ) an dLocatio n 8 - OW-302 B 72 0 - OW-302 B MU L



### 5 7 5 ME G

5 2 7 iy» y KULJ targe t | | Cleanu p Level s (Mg/L ) 

## 2 5 7 Dichlorobenzen e PCBs 1 4 4 - OW-302 B 0. 5 

### 0.0 5 0. 5 Chlorobenzen e 

### 1,2

- Dichlorobenzen e 

### 1,3

- Dichlorobenzen e 1,2,3

- Trichlorobenzen e 1,2,4

- Trichlorobenzen e 1,3,5

- Trichlorobenzen e 24 0 - OW-302B 210-OW-302 B 16 0 - OW-302 B 9 8 -OW-302 B 77 0 - OW-302 B no t analyze dfo r 

### 10

0 60 0 N S N S 7 0 N S 4 7

8 5 8 5 N S 7 0 4 0 n o RO D standar d1

n o RO D standar d n o RO D standar d n o RO D standar d n o RO D standar d n o RO D standard 

### I I 1 detectio n limi t

varie s with locatio n an dare generall y greate r tha n th e 199 2 MEG . N S - n o standar d 2 . Spatia l Exten t

o f th e Technica l Impracticabilit y Zon e Thi s sectio n describe s th e horizontal an dvertical exten t ove r whic h th e Technica l Impracticabilit

y decisio n woul dappl y (T I Zone) . Thi s include s th e portio n o f groundwate r know n t o contai n VOC s abov e federa l MCL s an dStat e MEG s that woul drequir e substantia l timeframe s t o remediat e usin g currentl y availabl e technologies . Th e propose dT I Zon e horizontall y encompasse s th e TW A I I Are aan dth e are aassociate dwit h shallo w groundwate r

flo w t o th e south o f

th e TW A I I Area . Vertically , th e propose dT I Zon e extend s int o bedrock . Th e T I Zone , a s show n i n Figure 3 , include s area s wher e VOC s an dPCB s ar e presen t

i n groundwate r

a t concentration s abov e RO D targe t cleanu p goal s an dcurren t MCL s an dMEGs . Thi s i s principall y th e TWA-I I area . Overall , analytica l result s fro mmonitorin g well s MW-501 , MW-502 , MW-503 , MW-505 , MW-509A , MW-510A , an dMW-511 A locate d alon g th e boundar y o f

th e T I Zone , sho w tha t

concentration s o f

th e seve n VOC s an dPCB s detecte d durin g semi-annual groundwate r monitorin g event s ar e belo w RO D targe t cleanu p goal s an dcurren t

MCL s an dMEGs . 1 7I n revie w o f th e T I evaluatio n report , Main e DE P note dthat th e T I zon e include dmos t o f th e forme r uppe r lagoon . EPA recognizes , jus t a s th e boundar y o f

th e Designated Are ai s bein g simplifie di n thi s RO D Amendment s o tha t it ma y b e easil y identified , the TI zon e ha s als o bee n establishe di n part

to allo w fo r

it s easy identificatio n whil e onsite . Consequently , whil e th e uppe r lagoo n wa s successfull y remediate ddurin g th e SCRA , aportio n o f i t fall s withi n th e T I zon e a s aresul t

o f simplifyin g th e T I boundary . 3 . Conceptua l Mode l Th e conceptua l mode l serve s a s afoundatio n fo r evaluatin g th e restoratio n potentia l o f th e sit e and , thereb y assessin g th e technica l impracticabilit y a s well . I t include s th e sit e geolog y an d hydrogeology , natur e an dexten t o f Contaminant s o f

Concer n i n groundwater , fat e an dtranspor t processes , an dcurren t

o r potentia l receptors . Thi s conceptual mode l ha s bee n develope dthroug h revie w o f report s o f

previou s investigation s an dth e visual inspectio n o f subsurfac e material s durin g sourc e contro l work . Th e SCR A involve dth e excavatio n o f asignificant

portio n o f

th e site' s overburden , and , i n some places , exposur e o f th e bedroc k

surface . Thi s summar y o f

th e conceptua l mode l wa s presente di n th e Jun e 200 2 Technical Impracticabilit y Evaluatio n report . A . Sit e Geolog y an dHydrogeolog y A summar y o f

th e geolog y an dhydrogeolog y fo r th e overburde n an dbedroc k a t th e sit e i s provide dbelow . 1 . Overburde n Geolog y Soi l material s o n th e sit e includ e glacia l marin e silt s an dclay s an dglacia l til l overlyin g bedrock . Th e uppe r

cla y uni t ha s tw o stratigraphi c members : a n upper , stiff , desiccate dbrow n membe r an dalower , soft , gra y member . Th e uppe r brow n membe r

whic h typicall y make s u p th e uppe r 1 0 t o 2 0 fee t

o f th e cla y unit , i s blocky an dhighly fractured . Th e lowe r gra y membe r

i s absen t o r discontinuou s i n th e uplan dareas , wher e tota l overburde n thicknes s thin s t o les s tha n 2 0 feet . Th e cla y tend s t o b e absen t onl y i n area s o f

shallo w bedrock . Th e til l i s discontinuous , varyin g i n thicknes s fro m0 t o approximatel y 4 2 fee t (B-503) . Th e til l range s fro macoars e granular materia l overlyin g th e shallo w bedroc k i n th e norther n an dwester n portion s o f

th e site , t o thick , dense , fine-graine dsoil s overlyin g th e deepe r bedroc k i n th e centra l an deaster

n portion s o f

th e site . I n th e TW A I I Area , th e til l i s approximatel y 0 t o 9 fee t thick . Th e til l i s essentiall y absen t alon g th e axi s o f

th e bedroc k

ridg e fro mth e centra l t o th e norther n portio n o f

th e site . Th e change s i n th e observe dtexture s o f til l ar e inferre dt o resul t

fro m weathering . Figur e 7 show s th e locatio n o f thre e geologi c cros s section s acros s th e site . Figur e 8 , Figur e 9 , an dFigur e 1 0 ar e th e geologi c cros s section s showin g th e inferre dsoi l stratigraph y an dbedroc k 

### 1 8

### morphology . The stratigraphi c elevation s hav e bee n inferre dfro mthe boring s represente do n the profiles . Th e inferre dgeologi c stratigraphy i s th e result o f th e MO M Additional Investigation s Repor t (W& C 1996a

) an dexisting boring s o n the sit e prio r t o 1996 . Th e till/bedroc k

interfac e i s th e primary migratio n pathway o f contaminants . Th e result s fro m severa l wells , includin g B-506 , B-510 , B-514 , an dMW-504 , indicate arelatively highly conductiv e water-bearin g zon e alon g th e till/bedroc k interface . I n eac h o f

thes e borings , ver

y littl e wate r

wa s observe ddurin g th e drillin g proces s unti l th e dril l bi t penetrate dth e lowe

r 2 t o 3 fee t o f th e til l immediatel y abov e th e bedroc k surface . Th e potentiometri c surfac e i n eac h o f thes e boring s wa s severa

l fee t higher tha n th e permeabl e zone , indicatin g aconfine dcondition . Th e permeabl e zon e associate dwit h th e til^edroc k

interfac e coul db e th e resul t o f an erosional water-worke denvironmen t i n th e initial stage s o f

til l deposition . Th e soi l stratigraph y i n th e Uplan dMars h are aan dTW A I I Are awa s furthe r refine ddurin g an Uplan dMars h investigatio n conducte dt o identif y th e presenc e an ddistributio n o f oi l detecte di n an Uplan dMars h piezometer UM-1 . Thi s stud y helpe drefin e th e hydrogeolog y i n th e TW A I I Are aan dth e hydrogeologi c interactio n o f th e desiccate dcla

y with th e till/bedroc k

migratio n pathway . Th e stratigraphy o f

th e soi l materia

l i n th e Uplan dMars h are aconsist s o f approximatel y 4 to 1 0 fee t o f desiccate dbrow n cla

y overlyin g approximatel y 1. 5 t o 7 fee t o f soft , unfracture dgray cla y that overlie s 2 t o 4 fee t

o f till directly i n contac t

wit h bedrock . Thes e differen t layer s pinc h ou t i n area s o f

shallo w bedrock

(GeoProb e borin g G-14) . Groundwater i s confine di n th e til l an d predominatel y move s alon g th e till/bedroc k interface . Surfac e wate r

infiltrate s int o th e fracture s i n th e brow n cla

y an di s quasi-perche do n to p o f th e sof t clay , makin g itself

availabl e fo r evapotranspiration . Base do n histori c Water

elevation data , th e quasi-perche dwater tabl e i n th e brow n cla y fluctuate s a s muc h a s 6 t o 8 fee t durin g th e year . Figure 1 1 show s aplan vie w o f th e site wit h th e GeoProb e location s an dth e locatio n o f thre e cros s sectio n lines . Figure 12 , Figure 13 , an dFigure 1 4 are th e geologi c cros s section s throug h th e Uplan dMars h are adepictin g th e stratigraphy , origina l groun dsurfac e prio r t o sourc e control , an dth e existin g groun dsurfac e afte r sourc e control . I n general , th e thickes t

portion s o f

th e desiccate dcla

y wer e i n th e Uplan dMars h are awher e th e sit e topograph y flatten s (G-8 , G-9) . Th e stratigraph y remain s relativel y consisten t excep t i n th e norther n portio n o f

th e stud y are a(probe s G-12 , G-13 , G-14 , G- l 5 , an dG-16 ) wher e th e bedroc k surfac e rises andthe sof

t cla y pinche s out . See Figur e 13 andFigur e 14. In thi s are athe desiccate dclay i s i n contac t with th e till . 2 . Bedroc k

Geolog y Th e shallo w an ddee p bedroc k flo w syste ma t

th e sit e wa s studie di n severa l pre - an dpost-RO D investigations . Th e 199 6 fiel dstud y investigate dth e bedroc k surfac e i n a n effor t

t o understan d th e potentia l migratio n pathwa y alon g th e to p o f th e bedrock . Th e inferre dbedroc k surfac e elevatio n i s depicte di n Figur e 15 . Th e bedroc k surfac e morpholog y can als o b e viewe do n th e 1 9geologi c profile s o n Figure s 8-1 0 an dFigure s 12-14 . Th e bedroc k surfac e wa s verifie ddurin g sourc e contro l work , i n location s where soi l wa s excavate ddow n to th e bedroc k surface . Th e bedroc k

surfac e consists o f

ahard , minimally weathere dquart z monzonite . Drillin g log s fro mforme r

investigation s indicat

e metasedimentar

y bedrock intersperse d wit

h th e quart z monzonit e o n th e easter

n portio n o f

th e site (MW-406B ) suggestin g acontac t betwee n th e intrude dmonsonit e an dth e surroundin g metasedimentary rock . Th e bedroc k

structura l feature s were evaluate dbot h locall y an dregionall y i n th e Photogrammetri c Analysi s an dOutcro p Stud y (E . C . Jordan , 1986) . Thi s evaluatio n utilize d photogrammetri c analysi s includin g th e examinatio n o f aeria l photograph s an dradar

imagery . Additionally , fiv e bedroc k outcrop s wer e examine di n th e vicinit y o f th e site . Thi s stud y include dinformatio n regardin g th e existenc e an dorientatio n o f bedroc k fracture s presen t

i n th e crystallin e rock s i n th e area . Result s o f thi s stud y determine dtha t th e regiona l structura l orientatio n i s i n anortheast-southwes t orientation . Thre e prominen t NE/S W lineament s wer e identifie di n th e vicinit

y o f th e sit e h i th e E . C . Jorda n study . Th e stud y als o determine dthat th e mos t commo n strike orientatio n wa s NE/SW . Th e Inferre dBedroc k

Surfac e ma

p provide di n Figur e 1 5 show s tha t th e bedroc k

ridg e i s oriente d generall y o n anortheast-southwes t axi s coinciden t

wit h th e previousl y identifie dregiona l structura l orientation . Th e bedroc k ridg e i s anatura l featur e that ha s bee n scarre dan drounde d b y th e las t

glacia l advanc e an dretreat . I t

i s aquart z monzonite an da s suc h ha s n o beddin g o r structura l foldin g orientation . Th e majo r structura l trend s outline di n th e E.G . Jorda n stud y refe r t o aNE/S W structura l orientatio n associate d with regiona l tectoni c compressio n history o f th e •coas t o f Main e (refe r

t o th e bedroc k

geologi c ma

p o f Maine) . Th e monzonit e intrusiv e i s part o f th e Devonia

n intrusive s whic h intrude dth e country rock o f th e regio n an di s generall y elongate d paralle l t o beddin g strik e o f th e countr y rock . Thi s ma y hav e ha dinfluenc e o n th e coolin g histor y an dpos t

placemen t

fracturin g o f

th e monzonite , bu t

i s believe dt o hav e n o direc t influenc e o n fracturin g o f th e intrusiv e bod y an dthu s n o influenc e o n groundwate r movement . Conclusion s o f

th e 198 6 E.G . Jorda n Stud y ar e a s follows :

• regiona l an dlocal strike orientatio n i s northeast/southwest ;

• exfoliatio n typ e o f

near-horizonta l fractur e surface s ar e unifor man dwidesprea d throughou t

th e area , • "fracture s wil l hav e th e mos t significan t

impac t o n groundwate r

flo w pattern s withi n th e roc k mass" ;

• groundwate r

flo w fro mth e sit e i s expecte dt o b e generall y coinciden t wit h topography , an d

• th e potentia l exist s fo r anortheast-southwes t

flo w barrie r

o r groundwate r

sin k i n th e vicinit y o f

Rigg s Brook . 2 0

### Th e bedrock drillin g i n al l investigation s indicatedmostl y competen

t rock wit h ver y fe w recognizable fractures . Th e rate o f bedrock drillin g wa s unusuall y slow . Occasionally , a t rando mdepth s belo w th e bedrock surface , th e downhol e drillin g equipment woul dadvanc e rapidly for

0. 2 to 0. 4 feet , indicatin g th e existenc e o f awea k weathere dlaye

r or fractur e i n th e bedrock . Afte r

encounterin g awea

k laye r i n th e bedroc k

o r abedroc k fracture , a

n increas e i n th e availabl e formatio n wate r

woul db e observed , indicatin g th e presenc e o f groundwater

i n th e fracture s i n th e upper

bedrock . Durin g sourc e contro l wor k where th e bedrock

surfac e wa s expose ddurin g soi l removal , th e bedroc k appeare dver y competent . Very fe w fracture s appeare d t o b e expose dalon g th e bedroc k surfac e an dnon e appeare dt o b e abl e t o suppl y an y significan t amoun t o f recharg e to th e bedroc k

flo w system . Bedroc k

outcrop s are foun di n th e are ao f TWA I I an dt o th e sout

h i n th e vicinit

y o f TW A I (refe r

t o Figure 2) . Generally , th e bedroc k

form s asaddle , wit

h th e center

o f th e saddl e immediatel y northeas t o f th e uppe r lagoo n (Figur

e 2) . Th e cente

r o f th e saddl e form s atroug h fille dwith til l an dth e overlyin g marin e clay . Figure 7 contain s geologi c cros s section s depictin g th e bedroc k troug h i n th e cente r o f th e saddle . Figur

e 9 i s acros s sectio n alon g th e center o f th e saddle an dFigure 1 0 show s th e bedroc k ridg e t o th e northeas t

o f th e center

o f th e saddle . Th e til l i s absen t alon g th e to p ridg e an dmarin e cla

y i s i n direc t

contac t with bedrock . Th e limite dfractur e network o f th e bedroc k

flo w syste man dlimite davailabl e recharg e fro mth e overburde n limit s flo w i n th e bedroc k aquifer . Recharg e t o th e bedroc k fro mth e overburde n i s limite db y th e lo w permeabilit y overburde n soil s an dlac k o f shallo w groundwate r

i n th e overburden . Becaus e th e bedroc k i s tight , limite dflo w move s throug h th e bedroc k system . 3 . Groundwate r

Flo w i n th e Overburde n an dBedroc k Flo w Syste m Th e principal groundwate r migratio n pathwa y o n th e site i s adiscrete zon e withi n th e til l alon g th e to p o f th e bedroc k

surface . Th e groundwate r flo w directio n i s asubdue dreflectio n o f th e bedroc k surface . Figur

e 1 6 show s th e inferre dgroundwate r flo w directio n superimpose do n th e bedroc k surfac e map . Groundwate r flo w fro mth e larg e recharg e basi n (Uplan dMarsh ) t o th e northwes t o f th e sourc e contro l are ai s confine dan dchannele dthroug h th e bedroc k troug h i n th e cente r o f th e bedrock

saddle . Th e reworke dtill alon g th e bedrock surfac e i s th e primar

y migratio n pathwa y leavin g th e sourc e area . Th e bedroc k ridg e wher e th e til l i s absen t (refe r t o Figure 10 ) inhibit s movemen t o f th e shallo w groundwate r flo w fro mth e sourc e contro l are at o th e southeas t

towar dRigg s Brook . Th e uppe r til l an dcla y ten dt o confin e th e groundwater , no t allowin g flo w ove r

th e bedroc k

ridg e a s depicte di n Figur e 16 , an dforcin g flo w throug h th e bedroc k trough . O n th e northwes t sid e o f th e ridg e an dwithi n th e bedroc k trough , groundwate r unde r pressur e wa s observe ddurin g th e drillin g o f boring s B-5I4 , MW-504 , B-510 , an dB-506 . O n th e southeas t

sid e o f th e ridge , i.e. , B-515 , B-509 , MW-501 , B-508 , an dB-50 4 (Figure 16) , ver y littl e groundwate r

wa s observe dan dth e groundwate r wa s ver y slo w t o recharg e th e wells . Unde r steady-stat e conditions , groundwate r i n thi s are awa s les s tha n 1 - 2 fee t abov e th e bedroc k surface . Conceptually , precipitatio n recharge s th e fracture dclay , till , an dbedroc k (wher e expose dat

th e 2 1surface) , an dflow s withi n th e shallo w groundwate r flo w regime . Unde r

static , non-stressed conditions , there i s ver

y littl e vertica

l mixin g between th e overburde n an dbedroc k groundwate r i n th e immediate are asurroundin g th e transforme r wor k areas . Althoug h adownwar dvertica l gradient exists , th e relatively lo w vertica l permeabilit

y o f th e bedroc k

inhibit s vertica

l migration . Groundwate r

recharg e t o th e fil l soil s use dt o re-grad e th e sit e followin g th e SCRA doe s no t chang e th e overall groundwate r flo w patterns . Th e bedroc k

ridg e inhibit s th e southeasterl y flo w o f shallo w groundwater . Th e onl y wate r availabl e t o flo w o n th e southeas t sid e o f th e ridg e come s fro mrecharg e throug h th e clay surfac e soil s an dgroundwate r

dischargin g fro mth e bedrock . Both source s o f recharg e t o th e til^edroc k migratio n pathwa y southeas t o f th e bedroc k

ridg e ar e very limited , leavin g somewha t dr y condition s withi n thi s migratio n pathway . Th e contaminan t distributio n alon g th e till/bedroc k interfac e an dth e recharg e o f th e monitorin g well s i n thi s area , a s describe dabove , support s thi s understanding . Long-termmonitorin g o f shallo w overburde n monitorin g wells , MW-50 1 an d MW-502 , indicate s ver

y littl e overburde n groundwate r i n thi s are ao f

th e site . Th e bedroc k

flo w regim e ha s ver

y littl e wate r

i n storage . Th e exfoliate dfractur e network i s far

reachin g an dderive s it s recharg e fro mth e uplan darea s surroundin g th e TWAs . Th e vertical permeabilit y o f

th e bedroc k

i s believe dt o b e ver y low , creatin g th e "quasi " perche dconditio n o f th e shallo w overburde n groundwate r flo w system . Over

mos t o f th e site , th e bedroc k groundwate r

i s unde r aconfine dcondition . I n th e southeaster n en do f th e site th e potentiometri c surfac e o f

th e bedroc k

groundwate r

i s abov e th e groun dsurface . MW-106 B i s i n th e southeaster n portio n o f

th e site an di s afree-flowin g artesian well . A s a n artesia n well , i t create s apressure release , an dprovide s aconditio n fo r contaminant s that

hav e entere d th e bedroc k flo w regime t o discharg e t o th e groun dsurface . Th e overburde n groundwate r i s "quasi " perched ; releasin g groundwate r fro mstorag e t o suppl y recharg e t o th e bedroc k

fracture s wher e possible . Th e horizonta l permeabilit y i n th e uppe r bedroc k zon e i s highe r

tha n th e vertica l permeability . Thi s i s eviden t whe n comparin g th e potentiometri c surfac e o f th e bedroc k

an doverburden . Groundwate r elevatio n dat aincludin g potentiometri c surfac e map s an dtim e serie s plot s at fou r wel l pair s ar e provide di n th e Jun e 200 2 Technica l Impracticabilit y Evaluatio n report . Althoug h mos t of the bedroc k

well s are ope n hole s (i.e. , n o screene dzone s set ) th e wel l couple s (i.e. , MW-10 3 A , B ) ar e separate db y acasin g advance dint o rock . Typically , th e overburde n well s ar e se t o n to p o f th e bedroc k

surfac e whil e th e bedroc k

well s ar e ope n hole s wit h groute dcasin g approximatel y fiv e fee t o r les s int o th e bedroc k surface . Historically , th e differenc e i n groundwate r potential s acros s thi s relativel y shor t distanc e has bee n on the orde r of 1 to 2 feet . Thi s downwar dgradien t in the sourc e contro l are a i s likel y du e t o th e lo w vertica l permeabilit y o f th e bedroc k

an dsupport s th e "quasi " perche d understandin g o f

th e vertica l groundwate r flo w fro mth e overburde n int o th e bedrock . Th e vertica l gradien t

i s downwar dover

mos t o f th e site . Th e vertical gradien t i s downwar dat wel l pai r MW-507A/MW-508B . Prio r t o th e abandonmen t

o f wel l pair s MW-102A/B , MW

105A/ B an dMW-401A/

B fo r Sourc e Control , thes e well s exhibite ddownwar dvertica l gradients .

2 2

### Th e vertica l gradient i s upwar da

t th e locatio n o f

wdl pai r MW-106A/B . Thi s well pai r i s locatedadjacen

t t o Rigg s Brook

an dmonitor s the confine dbedrock flo w syste mdowngradient fro mthe site . Bedroc k

a t thi s locatio n drop s considerably i n elevatio n an di s confine db y approximatel y 5 0 fee t

o f cla y soil s confinin g th e uplan dflo w fro mth e sit e to Rigg s Brook . Th e horizontal gradient s hav e been calculate dfo r bot h th e overburde n aquife r

an dth e bedroc k aquifer . Th e gradient s are simila r i n bot h aquifers . I n th e uplan dportion s o f th e site , th e horizontal gradient s ar e approximatel y 0.0 1 an d0.02 4 o n th e overburde n an dbedroc k aquifers , respectively . I n th e steepe r are abetwee n th e Upper

Lagoo n an dth e Lowe

r Lagoon , th e horizonta l gradient s ar e approximatel y 0.0 9 an d0.0 6 i n th e overburde n an dbedroc k aquifers , respectively . Durin g th e 199 2 pumpin g test , th e bedroc k observatio n well s (MW-103B , MW-104B , MW

105B , OW-201B , OW-204B , OW-301B , an dOW-302B ) responde drelatively quickl y and , wit h time , significant

drawdow n wa s observe di n bedroc k well s a s fa

r awa y a s MW-105B . Thi s indicate s tha

t groundwate r

i n storag e move dquickl y t o th e pumpin g wel l an dtha t recharg e (vertical ) fro mth e overburde n int o th e bedroc k wa s slow . Becaus e groundwate r wa s take n fro m storag e withi n th e bedroc k an dwa s vertically inhibite dfro mrechargin g th e bedroc k fro mth e overburden , recharg e t o th e pumpin g wel l cam e predominatel y fro mth e mor e regional networ k o f bedroc k fractures . Significan

t drawdow n wa s observe dlon g distance s fro mth e pumpin g well . Th e rapi drespons e observe di n th e bedroc k observatio n well s durin g pumpin g an dth e extent o f drawdow n withi n th e bedroc k support s th e conceptua

l understandin g tha

t th e bedroc k

ha s afar

reaching , interconnecte dfractur e networ k wit h avery lo w densit

y o f fracture s an dthus , a relativel y slo w vertica

l permeability an dvery littl e storage . Th e larg e variabilit

y i n hydrauli c propertie s o f th e bedroc k

lend s t o th e conceptua

l understandin g that the fractur

e network , althoug h loosel y connected , i n the bedroc k i s comprisedo f

ver y fin e micr o fracture s that

d o no t yiel dmuc h wate r

an dlarger

fracture s that

may yiel da s muc h a s 1 - 2 gpm . Th e bedroc k

i s relativel y tigh t

o n asite-wid e basis , a s observe db y th e perche dwate r table , visua l observation s durin g sourc e control , an dbedroc k RQ D analysi s don e durin g th e RI . Th e bedroc k

i n th e lower

elevation s (nea

r well MW-106B ) i s confined , an dal l flo w leavin g th e sit e throug h th e bedroc k

flo w syste mi s confine dt o flo w fro mth e site towar dRigg s Broo k flowage , the n paralle l t o th e Rigg s Broo k flowage , an deventuall y dischargin g t o th e Kennebe c Rive r Basin . Becaus e o f

th e confine dnatur e o f

th e bedroc k

system , associate dlo w gradient s acros s th e site , an dth e lo w hydrauli c conductivitie s o f th e bedrock , very littl e wate r flow s naturall y throug h th e system . Wel l MW-106 B intersecte dadeepe r fractur e tha t

i s relativel y wel l connecte dt o th e bedroc k fractur e networ k

flowin g fro mth e site . Whe n wel l MW-106 B wa s drilled , initia l concentration s o f sit e contaminant s at

thi s locatio n wer e non-detect . Becaus e o f th e confine dcondition s an dth e fac t tha t wel l MW-106 B wa s allowe dt o flo w continuously , bedroc k flo w wa s shor

t circuite d increasin g th e gradient

fro mth e sit

e an dflushin g th e bedroc k flo w systemtowar

dMW-106 B an d eventuall y u p an dou t

o f th e flo w systemthroug h thi s well . A s i s show n b y th e chemica l dat a 2 3fro mMW-106B , sit e contaminant s increase dafte r th e 199 2 pump test , whe n oi l wa s draw n dow n int o th e bedrock . Contaminan t concentration s measure da t MW-106B , however , neve r exceeded RO D cleanup goals . Sinc e then , wit h groundwate r

flo w unde r

stead y stat e conditions , th e chemica l dat aha s show n astead

y an dconsisten

t decreasin g trend . MW-106 B ha s provide da releas e o f

aportio n o f

th e bedroc k

flo w systemt o th e groun dsurfac e rather tha n flowin g of

f th e site . Conceptua l depiction s o f th e sit e hydrogeolog y befor e an dafte r sourc e contro l ar e presente di n figure s 1 7 an d18 . B . Sourc e o f

Contaminatio n A n assessment

o f th e groundwate r

collecte dfro mth e monitorin g well s installe ddurin g th e R I indicate dth e presenc e o f lo w level s o f

chlorinate dbenzene s i n monitorin g well s downgradien t o f TW A I I an dth e Uppe r

Lagoo n are a(MW-104 an dMW-103) . PCB s wer e onl y detecte d i n sample s collectedfro mMW-104B . Fro msubsequent investigations , i t

wa s foun dtha t

th e PCB s i n thi s wel l wer e no t

i n th e groundwate r

bu t wer e adsorbe dt o th e soi l particle s purge dfro mth e wel l durin g sampling . Th e PCB s associate dwith thes e particle s were th e resul t o f drillin g throug h PCB-contaminate dsurficia l soils . Wel l MW-104 B ha s onl y on e foo t o f casin g se t

int o rock . Surficia l sediment s can easil y migrat e int o th e borin g durin g well purging . Metal s detecte di n on-site well s wer e generall y comparabl e i n concentratio n t o upgradien t monitorin g an ddomesti c wells . Th e result s o f

th e R I samplin g work

indicate dtha t

PCB s fro mth e transforme r salvag e operation s occurre di n thre e forme r

work area s locate di n th e wester n portio n o f

th e site . Thes e activitie s le dto uncontrolle drelease s o f oi l containin g PCBs . I n addition , surfac e erosio n hadcause d PCB s t o migrat e ashor

t distanc e fro mth e work

areas . Smalle r

amount s o f

PCB s ha dpermeate d int o th e subsurfac e soils . Lo w level s o f PCB s wer e foun di n surfac e waters , sediments , an dbiot a samples . Lo w level s o f

othe r organi c an dinorgani c chemical s wer e als o foun di n som e media . Basedo n th e dat acollecte ddurin g post-RO D investigations , th e primar y sourc e o f both oi l an d chlorobenzene s wa s th e fracture s i n th e clay . Contaminant s wer e hel di n tensio n i n th e fracture s o f th e clay and , unde r

gravity , slowl y migrate dt o th e primar y migratio n pathwa y alon g th e till/bedroc k

surface . Du e t o th e immiscibl e natur e o f th e oi l an dit s measure dspecifi c gravit y o f 0.91 , th e oi l ha s remaine di n th e TW A I I Are awit h onl y smal l amount s enterin g int o th e primar y migratio n pathway . Th e chlorobenzene s wer e abl e t o dissolv e int o th e groundwate r an dmigrat e t o agreate r

degre e within th e primary migratio n pathway . Contaminan t

migratio n ha s no t

bee n significan t

beyon dth e TW A I I area . Th e followin g factor s serve dt o contro l and/o r

diminis h th e movemen t

o f chemical s i n soil s an dwater :

• lo w solubilit y o f

PCB s i n water ;

• th e stron g affinit y fo r PCB s t o adher e t o soi

l particles ; an d 2 4

### • th e presenc e o f thic k cla y an dtil l deposit s i n th e nea r surfac e an ddee

p groundwate r

regimes . Precipitatio n fallin g o n th e TW A II Are aeithe

r run s of f a s surfac e wate

r or infiltrate s downward int o th e overburden . A larg e portio n o f th e infiltratin g water

i s hel di n tensio n i n th e uppe r desiccatedcla

y laye r an di s quasi-perche do n to p o f th e sof t cla y layer , makin g itself

availabl e fo r evapotranspiration . Ver

y littl e recharg e enter s th e deepe r sof t cla y layers , an deven les s infiltrate s int o th e till/bedroc k flo w systemunde r

norma l conditions . Th e desiccate dcla y fracture s allo w alimite dmigratio n pathway fo r water t o mov e downwardtowardth e till/bedroc k migratio n pathway . C . Fat e an dTranspor

t Processe s Contaminant s o n sit

e migrate with th e directio n o f th e groundwate r

flow . Th e groundwate r

flo w directio n i s asubdue dreflectio n o f th e bedroc k

surfac e (Figure 16) . Th e lo w vertica l permeability o f

th e bedroc k

act s t o for ma"quas i perched " conditio n alon g th e to p o f th e bedrock . Althoug h i t

i s believe dtha t

th e bedroc k

receive s recharg e fro mth e uplan darea s northeas t o f th e bedroc k

trough , th e vertical permeabilit y o f th e bedroc k

i s extremely low , makin g th e bedroc k

amino r secondar y migratio n pathway . Ver y littl e contaminant

mas s enter s th e bedroc k

flo w syste mthroug h natura l groundwate r flo w an dgroundwate r

recharge . Contaminan t

mas s that

i s abl e to enter

th e bedroc k

flo w regime unde r

stati c non-stresse d condition s flow s withi n th e fracture networ k o f th e rock . Th e storag e o f

groundwate r

withi n th e bedroc k i s extremely low . Recharg e to apurge dwel l mos t likel y come s fro masignificant distanc e away fro mth e monitorin g wel l du e t o th e lo w storag e capacit y o f th e bedrock . Th e overlyin g till an dmarin e cla y confine s th e bedroc k

aquife r a t lowe r elevations . MW-106 B ha s bee n lef t flowing , providin g areleas e fo r contaminant s migratin g withi n th e dee p bedroc k flo w regim e an dlikel y represent s th e groundwate r withi n th e bedroc k

syste mthat

woul dhav e otherwis e migrate dfro mth e site . I f MW-106 B di dno t

exist , i t i s believe dtha t

bedroc k groundwate r

dischargin g fro mtha t

wel l woul dleav e th e sit e flowin g t o th e east , wher e i t woul d the n flo w nort h roughl y paralle l t o th e Rigg s Broo k drainag e an dtoward s th e regional groundwate r

sin k o f th e Kennebe c Rive

r Basin . Groundwate r

withi n th e primar y til^edroc k migratio n pathwa y move s alon g th e bedroc k surfac e i n th e til l layer . Thi s migratio n pathway , lik e th e bedroc k flo w system , ha s ver y lo w storag e an d slo w groundwate r

velocities . Therefore , eve n i n th e tillfoedroc k migratio n pathway , very littl e wate r i s moving . Contaminant s entere dthi s flo w systemb y slo w recharg e fro mth e overlyin g clay fractur e network . Contaminant s i n groundwater , onc e i n th e till/bedroc k migratio n pathway , ar e restricte dfro mflowin g southeasterl y b y th e bedroc k ridg e an dflo w towar dth e natura l bedroc k troug h immediatel y northeas t o f th e uppe r lagoo n (refe r

t o figur e 16) . Th e bedroc k troug h act s a s aspillway , channelin g flo w fro mth e uplan darea s surroundin g th e TWA s an d releasin g i t

t o flo w southeasterl y towar dRigg s Brook . Sentine l monitorin g well s (MW-50 2 an d MW-503) , place dalon g th e fron t edg e o f contaminant s movin g throug h th e bedroc k trough , monito r th e long-ter

mcontaminan t

migratio n withi n th e tilMedroc k migratio n pathway . 2 5Dissolve dVOC s are migratin g wit h th e groundwater , however , du e t o dilution , th e concentration s o f

VOC s a t well s alon g th e boundary o f th e T I Zon e are belo w th e RO D targe t cleanu p goal s an dcurren t MCL s an dMEGs . Residual oi l containin g PCB s an dVOC s i s hel di n tensio n i n th e desiccatio n crack s i n th e cla y an dt o alimite dextent

i n fracture s i n th e bedrock . Unde r natura l conditions , ther e i s ver y littl e movemen t

o f thi s oil . Concentration s o f PCB s i n monitorin g well s alon g th e boundar y o f th e propose dT I Zon e hav e bee n belo w th e RO D targe t cleanu p leve l o f

0. 5 ^g/L . However , durin g asamplin g even t

conducte di n Marc h 199 9 usin g lowe r detectio n limits , concentration s o f PCB s were at o r slightl y abov e th e 199 2 Main e ME G o f 0.0 5 /zg/ L at MW-50 3 an dMW-106 . Thes e well s ar e o n th e boundar y o r outsid e o f

th e propose dT I Zone . Continue dmonitorin g wil l b e conducte dt o determin e i f concentration s o f

PCB s outsid e th e propose dT I Zon e mee t th e 199 2 Main e MEG . 4. 0 Evaluatio n o f

th e Restoratio n Potentia l Thi s sectio n evaluate s th e restoratio n potentia l b y assessin g th e performanc e o f remedial action s previousl y conducte dan dthos e tha t ar e ongoin g at

th e site , an devaluate s additiona l technologie s t o determin e i f

an y coul drealisticall y attai n drinkin g wate r standard s fo r

th e sit e withi n a reasonabl e tim e frame . Remedial action s hav e been conducte di n thre e operabl e unit s at th e site ; OU- 1 Sourc e Contro l Operabl e Unit , OU- 2 Managemen t o f Migratio n Operabl e Unit , an dOU- 3 Rigg s Brook . Remedia l action s a t

operabl e unit s OU- 1 an dOU- 2 ar e discusse dbelow , a s the y ar e relevan t t o th e concentratio n o f

contaminant s i n groundwate r at th e site . A . Sourc e Contro l Measure s Th e SCR A fo r

OU- 1 wa s successfull y complete do n Novembe r 11 , 1997 . Th e sourc e remediatio n wa s conducte db y samplin g an dexcavatin g soil s an dsediment s contaminate dwit h PCBs , lead , an dcPAH s abov e th e RO D an dES D targe t cleanu p goals . Approximatel y 20,00 0 ton s o f soi l an dsedimen t

were remove dfro mth e site . Anothe r 3,00 0 ton s were excavate dan d consolidate dint o th e designate dare a(refe r t o Figur e 5 ) t o mee t

th e ES D targe t

cleanu p goals . Soi l an dsedimen t

i n OU- 1 wer e sampled , excavate dan dre-sample dunti l ther e wa s n o indicatio n o f soi l containin g PCBs , cPAH s o r lea dabov e th e targe t

cleanu p goals . B y meetin g th e require d targe t cleanu p goal s fo r

soil s an dsediment , an dremovin g sit e surfac e waters , th e SCR A achieve dth e remedia l actio n objective s establishe dfo r th e Sourc e Contro l componen t i n th e 198 9 ROD . Eve n afte r

th e successfu l completio n o f th e SCRA , som e residua l oi l containin g PCB s an dVOC s remain s trappe di n desiccatio n crack s i n th e clay an dt o alimite dexten t i n fracture s i n bedroc k

a t th e site . Althoug h residua l oi l remain s i n tensio n i n crack s i n th e clay , whe n i t ha s bee n analyze d i n ahomogenize dcla

y sample , th e concentration s hav e bee n belo w th e targe t cleanu p goals . Therefore , althoug h thi s remed y wa s no t abl e t o remov e al l th e residua l oil , th e approve dSCRA 2 6

### remediate dth e sourc e are aan dmet th e remedia

l actio n objective s statedi n th e ROD . Th e subsequent

Uplan dMars h study confirme dthat th e remedia

l objective s o f

th e SCRA were met , even thoug h som

e residua l oi l remains . The Uplan dMars h Stud y als o confirme dtha

t concentration s o f

PCB s detectedi n the dessication crack s i n the cla y containin g oi l range dfro m N D to 1 ppm . Therefore , concentration s o f PCB s i n th e fracture s di dno t exceedth e RO D targe t cleanup level o f

1 pp mestablishe dfo r

th e site . B . Analysi s o f

Remedia l Actio n Performanc e an dRestoratio n Timefram e Th e groundwate r

remedial alternativ e stipulate di n th e 198 9 RO D wa s th e installatio n an d operatio n o f

apum p an dtrea

t system . Durin g th e developmen t o f th e conceptua l understandin g o f th e site , th e effectivenes s o f th e pum p an dtreat

syste mwa s evaluated . Thi s evaluatio n indicate dthat

atraditional pump an dtrea t systemcoul dmobiliz e contaminant s verticall y downwar dan dfurthe r

contaminate groundwater . Consequently , aVE Rsystemwa s chose n rathe r than atraditiona

l pump an dtrea

t system . Th e constructio n an doperatio n o f th e VE R syste mdiffere dfro mth e pump an dtrea t system , a s originall y conceived , i n tha t i t extract s oi l an dwate r

fro mth e sit

e withou t significantl y lowerin g th e groundwate r table . Thi s woul dlimi t th e drawdow n o f

th e water tabl e int o th e bedroc k

an dtherefore no t

allow mobilize dresidua

l oi l t o ente r th e bedrock , whic h coul dfurthe r contaminat e th e bedroc k groundwater . A s described i n detail i n the Draf t Propose dFina

l Managemen

t o f Migratio n Remed

y (W&C , 1997d) , th e VERpilo t

study wa s conducte dwit

h th e objectiv e o f

recoverin g oi l both i n th e saturate dan dunsaturate dzone s withou t furthe r contaminatin g th e bedroc k groundwater . Th e operatio n o f

th e VE Rpum p an dtrea t

syste m(Phase s I an dI I conducte di n 199 6 an d1997) , couple dwit

h th e long-ter

moperatio n an dpulsin g o f th e system , resulte di n th e remova l o f 26. 6 gallon s o f oi l fro mwithi n th e primary migratio n pathwa y an dfro msourc e area s withi n cla y fracture s i n the TW

A II Are a(se

e Tabl e 4) . Durin g Phas e I I o f

th e VE Rsyste moperation , th e limitation s o f th e aquife r

wer e realize dwit h respec t t o oi l recovery . Som e o f th e residua l oi l i n th e immediat e vicinit y o f th e VE Rwel l wa s removed , bu t

a s vacuu mpressur e decrease dawa y fro mth e well , surfac e tensio n force s an d limitation s inherent

wit h multi-phas e flo w inhibite dth e movemen t o f residua l oi l t o th e well . Th e VE Rsyste mwa s the n pulsed , t o create astres s i n th e system , i n an effor t t o induc e produc t recharg e t o th e extractio n well . Followin g tw o week s o f operation s (Phas e II) , th e syste mwa s pulse dfo r

anothe r thre e month s i n an effor t

t o try an dremov e a s muc h oi l a s possible . Durin g thi s time , approximatel y 1 0 gallon s o f oi l wa s remove donl y whe n th e syste mwa s pulsed . Followin g th e completio n o f th e SCRA , passiv e oi l recover y ha s been conducte di n bedroc k well s i n th e TW A I I Area . Th e amoun t o f oi l recovere dpassivel y betwee n Decembe r 199 7 an d Augus t 200 1 wa s 7. 1 gallons . I n th e past , th e VE Rsyste mha dsuccessfull y remove doi l fro m th e till/bedroc k

interface ; therefore , i n Augus t 200 1 VE RPhas e II I systemoperatio n wa s initiate dt o addres s th e remova l o f oi l i n bot h th e bedroc k

an doverburde n soils . A tota l o f 19. 8 gallon s wer e recovere ddurin g thi s VE Roperatio n compare dt o 26. 6 gallon s collecte ddurin g Phas e I an dPhas e I I VE Roperation . Followin g th e VE RPhas e III , betwee n Novembe r 200 1 an d 2 7Marc h 2002 , 1. 9 gallon s o f oi l were recovere dpassivel y fro mth e wefls . Mos t o f thi s oi l (1. 7 gallons ) wa s recovered i n OW-302B , an dappear s to b e directl y relate dto oi l induce dto th e wel l b y the VER . The tota

l oi l since the SCR

A completio n i s 28. 8 gallon s (Phas e III an d the passive recovery) . Base do n th e result s o f

groundwate r

monitorin g dat aan dth e studie s complete donsite , th e groundwate r

an dmas s flu x throug h bot h th e bedroc k an doverburde n flo w system s appear s t o b e very low . Du e t o removal o f contaminate dsourc e soil s durin g th e SCRA , an dremoval o f additiona l residua l oi l fro mth e overburde n an dbedrock , th e concentration s o f VOC s i n groundwate r

hav e bee n reduce dan dar e expecte dt o continu e t o decrease . Concentration s o f VOC s ar e belo w MCL s an dMEG s outsid e o f th e T I Zone . A t

MW-104 B an dOW-201B , jus t insid e th e propose dT I Zone , bu t outsid e o f

th e TW A I I Area , VOC s slightl y excee dMEGs . Base do n th e observe dtrend s o f decreasin g VO C concentration s i n thes e wells , i t i s estimate d tha t VO C concentration s wil l b e belo w MCL s an dMEG s at well s outsid e th e TW A I I Are a withi n th e nex t

5 t o 1 0 years . A s note di n th e discussio n o f oi l movemen t

withi n th e subsurface , recover y an do r treatmen t

o f residua l oi l wil l b e difficult . I t i s believe dtha t

i t coul dtak e hundred s o f

year s t o remov e th e residua l oi l an dmee t

drinkin g wate r

standard s fo r

PCB s an dVOC s withi n th e TW A I I Area . A s previousl y stated , residua l oil , th e primary sourc e o f PCB s an dVOCs , i s trappe di n fracture s i n clay an dbedroc k

withi n th e TW A I I Area . Th e quantit y o f residua l oi l remainin g i s unknow n an ddu e t o surfac e tensio n an dothe r force s holdin g thi s residua l oi l i n equilibrium , ther e i s littl e migratio n unde r

norma l conditions . Eve n thoug h th e VE Rsyste mha s remove damoderate amoun t o f residua l oil , an dmay continu e t o remov e oil , th e difficult y o f inducin g oi l movemen t

withi n th e clay desiccatio n crack s an dth e bedroc k fracture s make s i t

unlikel y tha t

th e residua l oi l ca n b e completel y removed . Therefore , ther e wil l alway s b e residua l oi l availabl e t o wate r infiltratin g int o th e TW A I I Area . Becaus e th e TW A I I Are ai s a t

th e to p o f

th e ridge , ther e i s littl e groundwate r flo w throug h thi s are a Mos t o f th e groundwate r

flo w throug h th e TW A I I Are ai s fro mth e infiltratio n o f rainwate r

an d snowmelt . Th e infiltratin g wate r wil l dissolv e PCB s an dVOC s t o their respectiv e solubilities , continuin g t o ad ddissolve dsourc e t o th e groundwate r withi n th e TW A I I Area . I n orde r t o estimat e th e dissolutio n tim e o f PCB s withi n th e oil , asimpl e solubilit y calculatio n wa s done . Thi s calculatio n di dno t incorporat e th e dissolutio n o f th e oi l itself . I t

i s believe dtha t th e oi l wil l remai n essentiall y unchange dan dth e PCB s wil l dissolv e ou t o f th e oi l Assumin g tha t ther e i s approximatel y 10 0 gallon s o f oi l lef t a s residual , wit

h a n averag e concentratio n o f 300 0 pp b an dasolubilit y o f 2. 7 pp b (USEPA , 1990 ) an dassumin g approximatel y 2. 5 gp m groundwate r

flo w throug h th e syste ma t adissolutio n concentratio n o f 20 % o f solubility , th e tim e t o dissolv e th e PCB' s woul db e 37 2 years . Give n dissolutio n o f 10 % o f solubility , tim e t o dissolv e woul db e 74 4 years . A s note dabove, sinc e th e quantit y o f residua l oi l remainin g i n th e subsurfac e i s unknown , on e hundre dgallon s wa s chose n a s areferenc e point . Th e technical impracticability evaluatio n identifie dan dscreene deightee n technologie s t o asses s 2 8

### their

abilit y t o restor

e th e groundwater

t o drinkin g wate r

qualit y withi n areasonabl e timeframe . Thes e technologie s include dinsit u applicatio n o f

oxidizers , alternate groundwate r containment approaches , a s wel

l a s excavation o f

all overburde n soil . The evaluatio n conclude dthat non e o f thes e technologie s woul dachiev e th e cleanu p goal s withi n areasonabl e timeframe . I n summary :

• Th e majorit y o f

PCB s were remove ddurin g th e SCRA i n 199 6 an d1997 ; residua l oi l containin g PCB s an dVOC s remain s trappe di n bedroc k fracture s an ddesiccatio n fracture s i n th e clay ;

• Site investigation s sho w tha t ther e i s littl e movemen t

o f residua l oi l containin g PCB s an d VOC s fro mth e TW A I I Area ;

• Th e VE Rsyste mha s ha dmoderat e succes s removin g oi l fro mth e bedroc k an doverburden ;

• A Restrictiv e Covenant ha s bee n signe db y CM P an dMain e DE P tha t prohibit s us e o f

th e groundwate r

beneat h th e site . Publi c wate r

i s availabl e o n Rout e 1 7 t o th e sout h an dCon y Roa dt o th e west . Th e neares t know n residential wel l i s approximatel y ahal f mil e t o th e east , situate do n ahill abou t

tw o hundre dfee t

abov e th e Rigg s Broo k

discharg e area . Thi s wel l intercept s flo w movin g wes t towar dRigg s Brook . Therefore , there i s n o curren t drinkin g wate r exposure ;

• Base do n th e observe dtrend s o f decreasin g VO C concentration s i n groundwate r sinc e th e completio n o f

th e SCRA , i t

i s estimate dthat

VO C concentration s a

t well s outsid e o f

th e TWA I I Are awill b e belo w MCLs.an dMEG s withi n th e nex t 5 to 1 0 years ; an d

• Du e t o th e difficulty o f removin g residual oil , i t

i s believe dthat

i t coul drequire hundred s o f year s t o remov e residua l oi l an dmeet drinkin g wate r

standard s fo r

PCB s an dVOC s withi n th e TW A I I Area . 5 . Cos t Estimate s Th e cos t estimat e o f

th e amende dremed y i s describe di n Sectio n X below . Mor e detaile dinformatio n regardin g th e technica l impracticabilit y o f restoratio n o f

th e overburde n an dbedroc k

groundwate r

ca n b e foun di n th e Fina l Technica l Impracticabilit y Evaluatio n Report . (W&C , Jun e 2002 ) 

### IX . COMPARATIV E ANALYSI S O F TH E ORIGINA L REMED Y AN D OU- 2 ALTERNATIVE S Sectio n 121(b)(l ) o f

CERCL A present s severa l factor s tha t

EP A i s require dt o consider i n it s 2 9assessment o f alternatives . Buildin g upo n thes e specifi c statutory mandates , th e NC P articulate s nin e evaluatio n criteri ato b e use di n assessin g remedia l alternatives . Thes e criteri aare a s follows : Threshol d Criteri a I n accordanc e wit

h th e NCP , tw o threshol dcriteri amus t b e me t i n orde r fo r th e alternativ e t o b e eligibl e fo r

selection : 1 . Overal l protectio n o f huma n healt h an dth e environmen t addresse s whethe r

o r no t a remed y provide s adequat e protection , an ddescribe s ho w risk s pose dthroug h eac h exposur e pathwa y ar e eliminated , reduce do r controlle dthroug h treatment , engineerin g control s o r

institutiona l controls . 2 . Complianc e wit h applicabl e o r relevan t an dappropriat e requirement s (ARARs ) addresse s whethe r

o r no t aremed y wil l meet

al l o f th e ARAR s o f

promulgate dstat e an d federa l environmental an dfacility-sitin g requirements , an di f not , provide s th e ground s fo r invokin g aCERCL A waiver(s ) fo r thos e requirements . Primar y Balancin g Criteri a Th e followin g fiv e criteri aar e use dt o compar e an devaluat e thos e alternative s whic h fulfil l th e tw o threshol dcriteria . 3 . Long-ter meffectivenes s an dpermanenc e assesse s alternative s fo r th e long-ter m effectivenes s an dpermanenc e the y afford , alon g with th e degre e o f certaint y tha t

the y wil l b e successful . 4 Reductio n o f

toxicity , mobilit y o r

volum e throug h treatmen t addresse s th e degre e t o whic h alternative s emplo y treatmen t t o reduc e toxicity , mobilit y o r volume , an dho w treatmen t i s use dt o addres s th e principl e threat s pose db y th e site . 5 . Shor t ter meffectivenes s addresse s th e perio do f tim e neede dt o achiev e protectio n an d an y advers e impact s o n huma n healt h an dth e environmen t tha t ma y b e pose ddurin g th e constructio n an dimplementatio n o f th e alternativ e unti l cleanu p goal s ar e achieved . 6 . Implementabilit y addresse s th e technica l an dadministrativ e feasibilit y o f a n alternative , includin g th e availabilit y o f material s an dservice s neede dt o implemen t aparticula r option . 7 . Cos t include s estimate dcapita l a s wel l a s operatio n an dmaintenanc e costs , o n ane t present-wort h basis . Modifyin g Criteri a

3 0

### The tw o modifyin g criteri adiscusse dbelo w ar

e usedi n the fina l evaluatio n o f remedia l alternative s generally afte r EPA ha s receivedpubli c comment o n th e RI/F S an dPropose dPlan . 8 . Stat e acceptanc e addresse s th e State' s positio n an dke y concern s relate dto th e preferre d alternativ e an dother

alternatives , an dth e State' s comment s o n ARAR s o r th e propose d us e o f waivers . 9 . Communit y acceptanc e addresse s th e public' s general respons e t o th e alternative s describe di n th e feasibilit y stud y an dPropose dPlan . Th e followin g i s acompariso n o f th e 198 9 RO D remed y an dth e alternative s evaluate dfo r thi s RO D amendment , contrastin g eac h remedy' s component s wit h respect to th e nin e evaluatio n criteria . 198 9 Remed y Th e 198 9 RO D selecte dacomprehensiv e approac h t o th e contamination . Th e sourc e contro l action s include dth e cleaning , demolition , an doff-sit e disposal o f th e ba msituate dalon g Rout e 17 , removal an doff-sit e disposal o f th e standin g wate r

i n th e tw o lagoons , an dth e excavatio n an dtreatmen t

b y solven

t extractio n o f

th e soil s an dsediment s contaminate dwith PCBs , cPAHs , an dlead . Management

o f migratio n action s include dth e pumping , treatment , an ddisposal o f th e contaminate dgroundwate r fro mth e soi l an dbedrock , an dsamplin g o f sedimen t an dfis h i n Rigg s Broo k

fo r te n years . Alternativ e 1 : Institutiona l Controls , Long-Ter mMonitoring , an dPassiv e Oi l Recovery I n thi s alternative , EP A recognize s tha t th e groundwate r

beneath aportio n o f

th e site (T I zone , se e Figur e 3 ) wil l no t

b e o f drinkin g wate r

qualit y fo r

a n extende dperio do f

time , potentiall y mor e tha n ahundre dyear s fo r reason s state dabov e i n Sectio n VIII . Whil e th e are ao f August a where th e site i s locate dha s no t seen rapi dgrowt

h durin g th e time th e F . O'Conno r Compan y operate dor

sinc e it s closing , the are aca n reasonabl

y b e expecte dt

o experienc e som

e growt h durin g th e tim e perio dneede dt o reac h th e drinkin g wate r quality . Therefore , establishe dan d forma l control s ar e neede dt o preven t us e o f th e groundwate r

o n th e sit e an dt o preven t th e contaminatio n fro mspreadin g b y stressin g th e aquife r beneath th e site . CM P an dMain e DE P hav e entere dint o aRestrictiv e Covenan t tha t prohibit s us e o f

th e groundwate r

withou t prio r approva l fro mMain e DEP . Thi s Restrictiv e Covenan t wil l remai n i n plac e unti l terminate db y Main e DEP . Should , however , EP A fin dtha t thi s covenan t

i s n o longe r

protective , effective , o r i t interfere s wit h th e performanc e o f th e remedy , additiona l institutiona l control s wil l b e place d o n th e property . Operatio n an dmaintenanc e activitie s wil l ensur e tha t th e institutiona l controls remai n i n plac e an dar e effectiv e fo r

thei r state dpurpos e an dtha t

th e Site i s manage dproperl y t o maintai n th e 

### 3 1protectiv e laye r o f clea n soi l abov e thos e soil s with lo w level s o f PCBs . Long-ter mmonitorin g o f

th e groundwater

wil l allo w EPA an dMaine DEP to trac k th e residua

l oi l an ddissolve dPCB s an dVOC s withi n th e T I zon e an doutsid e o f it . Thi s dat awill allo w th e agencie s t o evaluate whethe r th e concentration s are continuin g t o decrease , whethe r th e contaminatio n i s movin g beyon dit s curren t limit , an dwhethe r

ther e i s achang e i n concentration s dischargin g int o Rigg s Broo k wetlands . I n th e even t

tha t th e monitorin g dat aindicat e a n increas e i n PC B o r

VO C levels , respons e action s wil l b e evaluated , an da s appropriate , implemente da s par t

o f thi s amende dROD . I n additio n t o thes e components , Alternativ e 1 woul dinclud e passiv e oi l recovery wher e absorben t material s woul dperiodicall y b e use dt o recove r fre e oi l whic h ha s draine dunde r norma l condition s int o th e TW A I I wells . Thi s woul dcontinu e unti l fre e oi l wa s n o longe r observe di n th e wells . Th e absorben t material s woul db e dispose do f at alicense dTS D facility . Th e estimate dperio do f

operatio n fo r

thi s alternativ e i s i n exces s o f on e hundre dyears . Th e estimate dne t

presen t wort h fo r

thi s alternativ e i s $622,000 . (Cost s wer e develope dfo r thirty year s pe r EP A guidance ; however , EP A expect s i t wil l tak e considerabl y longe r t o reac h drinkin g wate r quality. ) Alternativ e 2 : Institutiona l Controls , Long-TermMonitoring , Activ e an dPassiv e Oi l Recover y Thi s alternativ e i s EPA' s selecte dalternative . I t add s activ e recovery o f

residua l oi l t o th e component s include di n Alternativ e 1 . O n an annual basis , avacuu mwoul db e applie dt o well s withi n TW A I I t o dra w th e residua l oi l an dVOC s fro mth e soi l an dbedrock . EP A i s proposin g th e annua l applicatio n t o coincid e with norma l lo w groundwate r level s a s tha t

ha s bee n th e tim e whe n th e amoun t

o f oi l i n th e well s ha s bee n th e greatest . Eac h applicatio n woul dcontinu e a s lon g a s i t wa s practica l t o remov e th e oi l (th e criteri afo r thi s i s furthe r

discusse di n Sectio n X.2.) . Pas t applicatio n suggest s tha t eac h applicatio n woul dlas t abou t fou r t o si x weeks . Th e annua l application , fro myea

r to year , woul dcontinu e a s lon g a s i t wa s practical . Passiv e oi l recover y woul db e implemente dbetwee n th e activ e pumpin g efforts . Th e recovere doi l an dth e absorben t material s woul db e dispose do f a t alicense dTS D facility . Th e estimate dperio do f

operatio n fo r

thi s alternativ e i s i n exces s o f on e hundre dyears . Th e estimate dperio do f

operatio n fo r

th e activ e oi l recovery i s fiv e t o te n years . Th e estimate dne t presen t wort h fo r

thi s alternativ e i s $1,055,000 . (A s wit h Alternativ e 1 , cost s wer e develope dfo r thirt y year s pe r

EP A guidance ) EP A develope dthes e alternative s base do n informatio n containe di n th e 200 2 Technica l Impracticabilit y Evaluatio n submitte db y CMP , whic h i n tur n followe ddiscussion s wit h EP A an dMain e DE P regardin g site conditions .

3 2

### Compariso n o f th e Origina

l Remedy fo r

Groundwate r

an d th e OU- 2 Alternative s t o th e Nin e Criteri a 1 . Overall Protectio n o f

Human Healt

h an dthe Environment Thi s criterio n considers whether th e remedy , a s awhole , will protec t human healt

h an dth e environment . Thi s include s a n assessmen

t o f ho w publi c healt

h an denvironmental risk s are properl y eliminated , reduced , o r controlle dthroug h treatment , engineerin g controls , o r institutiona l controls . Th e origina

l remed y include dpum p an dtrea t technolog y a s th e metho dt o achiev e groundwate r restoratio n throughou t

th e Site . Whil e thi s technolog y wa s t o b e implemented , short-term institutiona l control s were t o b e se t i n plac e t o preven t

exposure t o th e contaminate d groundwater . Thi s selection wa s consistent with th e belie f

a t th e tim e tha t

thi s technolog y coul d effectivel y restore contaminate dgroundwater . I n 2002 , EP A conclude dtha t restoratio n wa s no t feasible . Therefore , without achievin g restoratio n withi n areasonabl e tim e fram e o r havin g a long-termmean s t o prevent exposur e t o th e contaminate dgroundwater , th e original remed y i s n o longe r protectiv e o f

human healt

h an dth e environmen t

i n th e long-term . Alternative s 1 an d2 recogniz e that fo r aportio n o f

th e site , i t

i s technicall y impracticabl e t o restore th e groundwate r

t o drinkin g wate r

quality , an dtherefore , t o preven t exposure t o th e contaminate dgroundwater fo r a n extende dperio do f

time , along-ter

minstitutional contro l i s a componen t

o f both alternatives . I n addition , both alternative s includ e long-ter mmonitorin g o f groundwate r

t o demonstrate that

th e contaminatio n i s no t

expandin g an dtha t

natura l processe s will continu e to decreas e th e contaminant concentrations . Alternativ e 2 provide s greater overal l protectio n b y actively removin g separat e phas e oi l fro mth e overburde n soi l an dbedroc k an d thu s mor e quickl y reduce s th e toxicity . Thereby , wit h th e institutional contro l provide db y th e Restrictiv e Covenant , thi s componen t ensure s th e protectivenes s o f th e remedy . Th e protectio n o f

huma n healt h an dth e environmen t i s th e mos t

importan t

criterio n Th e Restrictiv e Covenan t

protect s huma n health a s i t prevent s huma n exposur e t o contaminate d groundwater . Th e environment i s protecte dthroug h th e soi l remova l an drecover

y o f th e fre e oi l (b y removin g th e sourc e o f contamination , th e amount o f residual contaminatio n availabl e t o aquati c an dterrestrial receptor s i s expecte dt o continu e t o decrease) . Long-ter mmonitorin g wil l allo w EP A an dMain e DE P t o kno w whethe r th e remed y i s appropriate . Bot h alternative s EP A evaluate drel y o n th e Restrictiv e Covenan t an dlong-ter mmonitoring . 2 . Complianc e with Applicabl e an dRelevan t an dAppropriat e Requirement s Thi s criterio n addresse s whethe r o r no t aremed y complie s wit h al l promulgate dstat e an dfedera l environmenta l an dfacilit y sitin g requirement s tha t appl y o r ar e relevan t

an dappropriat e t o th e condition s an dremed y at

aspecifi c site . I f

a n ARA Rcanno t

b e met , th e analysi s o f

aremed y mus t provid e th e ground s fo r

invokin g astatutory waiver .



### 3 3Whe n th e origina l remed y wa s selecte di n th e 198 9 ROD , i t wa s believe dthat

th e remed y woul d attai n al l identifie dfederal an dstat e ARARs . Bot h alternative s includ e aT I waiver o f drinkin g wate r

standard s fo r

th e are aidentifie da s th e T I zon e (Se e Figur

e 3 ) an dwoul dcomply wit h al l othe r

identifie dfederal an dstate regulation s a s wel l a s drinkin g wate r

standard s outsid e o f

th e T I zone . PC B an dVO C level s outsid e th e T I zon e ar e currentl y belo w EPA' s standard s bu t at time s ar e slightl y abov e Maine' s standards . A s th e concentration s hav e decrease dfollowin g th e 199 7 soi l remova l action , an dactiv e an dpassiv e oi l recover y wil l continue , i t i s anticipate dtha t

th e Main e standar dwil l b e consistentl y me t outsid e th e T I zon e i n fiv e t o te n years . EP A anticipate s tha t activ e recover

y o f th e oi l unde r

Alternativ e 2 wil l mor e quickl y lower th e PC B an dVO C concentration s i n th e T I zon e tha n jus t th e passiv e recovery provide di n Alternativ e 1 . However , i t i s likel y tha t

at th e conclusio n o f

activ e recovery th e dissolve dconcentration s withi n th e T I zon e wil l stil l b e abov e th e drinkin g wate r standards . Becaus e th e RO D Amendmen t waive s federa l an dstat e drinkin g wate r standard s fo r

aportio n o f th e site , EP A sought

comment fro mth e publi c regardin g thi s durin g th e publi c commen t period . 3 . Long-termEffectivenes s an dPermanenc e Thi s criterio n refer s t o th e ability o f aremed y t o maintai n reliabl e protectio n o f huma n healt h an d th e environmen t

ove r tim e onc e th e remedial actio n i s complete . Th e origina

l remed y woul dhav e provide dlong-termeffectivenes s an dpermanenc e onc e sit e groundwate r

ha dbee n restore dt o drinkin g wate r quality . However , sinc e i t wa s demonstrate d tha t th e pum p an dtrea t

technolog y coul dno t

restor e th e groundwate r

within areasonabl e timeframe , there were concern s tha t th e Restrictiv e Covenan t alon e woul dno t

hav e th e abilit y t o , provid e an dmaintai n reliabl e long-termeffectiveness . Fo r thi s reason , additiona l institutiona l control s coul db e use di n th e futur e t o ensur e long-termeffectivenes s an dpermanenc e unde r bot h alternative s evaluate db y EPA . Th e long-ter mprotectio n criterio n woul db e me t b y bot h alternative s EP A evaluated . I f th e Restrictiv e Covenan t

i s no t effectiv e o r

protectiv e i n th e future , additiona l institutiona l control s wil l b e require db y EPA . Th e groundwate r monitorin g wil l continu e unde r bot h alternative s a s lon g a s th e PC B an dVO C concentration s remai n abov e drinkin g wate r quality . Additionally , operatio n an dmaintenanc e activitie s wil l continu e t o ensur e th e effectivenes s an dprotectivenes s o f th e institutiona l control s 4 . Reductio n o f

Toxicity , Mobility , an dVolum e throug h Treatmen t Thi s criterio n contain s thre e measure s o f th e overal l performanc e o f aremed y Th e 198 6 amendment s t o th e Superfun dstatut e emphasiz e that , wheneve r possible , EP A shoul dselec t a remed y tha t

use s atreatmen t

proces s t o permanentl y reduc e th e level o f toxicit y o f

contaminant s a t th e site , inhibi t

o r eliminat e th e sprea do f

contaminant s away fro mth e sourc e o f contamination , an dreduc e th e volume , o r amoun t o f contaminatio n a t

th e site . 3 4

### Th e origina l remed y fo r th e groundwater

operabl e uni t

use daprove n technology , pum p an d treat , to reduc e toxicity , mobility , an dvolum e i n th e overburde n an dbedroc k groundwater . However , a s note delsewhere , the presenc e o f separat e phas e oi l wit

h PCB s an dVOC s i n bot

h th e fracture s i n th e overburde n cla y soi l an di n th e bedrock , an dth e limite drecharg e o f groundwate r

i n th e contaminate dsourc e are agreatly limite dth e effectivenes s o f pum p an dtrea

t technolog y i n reducin g toxicity , mobility , an dvolume . Bot h alternative s woul dinclud e th e removal o f residua l oil . Alternativ e 1 woul dremov e th e oi l a s i t move s unde r

natura l condition s int o monitorin g wells , wherea s Alternativ e 2 woul dals o emplo y apumpin g syste mt o increas e th e rat e o f th e recovery . Th e recovere doi l i s transporte d offsit e to alicense

dTS D facility . Usin g activ e recover y unde r Alternativ e 2 , th e volum e o f th e residua l oi l wil l b e reduce dmuc h more quickl y the n relyin g o n natura l condition s a s propose di n Alternativ e 1 . I n turn , thi s will furthe r decreas e it s mobility throug h th e subsurface . Therefor e Alternativ e 2 provide s th e greates t reductio n o f

toxicity , mobility , an dth e volum e o f contaminant s throug h treatment . 5 . Short-ter

mEffectivenes s Thi s criterio n refer s to th e likelihoo do f advers e impact s o n huma n healt h o r th e environmen t

tha t may b e pose ddurin g th e constructio n an dimplementatio n o f aremedy . EPA doe s no t

believ e tha

t th e origina

l remed y fo r groundwater

posedsignifican

t short-ter m effectivenes s concerns . Th e potentia l exposure o f sit e worker s an dare aresident s t o contaminate dai r

emission s durin g constructio n o f th e extractio n an dre-injectio n well s wa s minimize db y usin g standar dsafet y plan s tha t

include dai r

emission s control s an danetwork o f ambient air monitor s to asses s potential release s to th e air durin g drillin g operations . Th e implementatio n o f

th e pump an dtrea

t technolog y likewis e di dno t pos e significant

short-ter m effectivenes s concerns . Bot h alternative s mee t

th e short-ter meffectivenes s criterio n i n simila r ways . Th e implementatio n o f

institutiona l control s reduce s sit e risk s fro mgroundwate r quickly . Th e onl y remedia l action s are th e long-ter mmonitorin g an dth e oi l recovery , both o f whic h hav e bee n ongoin g fo r

years , an dth e samplin g crew s follo w establishe dhealt h an dsafety procedures . A s state dabove , th e recovere doi l an dabsorben t material s ar e currentl y transporte dt o alicense d TS D facility an dwil l continu e t o b e shippe doffsit e safel y an di n accordanc e wit h al l legal requirements . 6 . Implementability Thi s criterio n refer s t o th e technica l an dadministrativ e feasibilit y o f aremedy , includin g th e availabilit y o f

material s an dservice s neede dt o implemen t th e remedy . Th e original groundwate r remedy wa s implementabl e a s demonstrate db y th e installatio n o f recovery an dre-injectio n well s tha t wer e operate dsuccessfull y durin g th e pilo t pumpin g studies . 3 5Bot

h alternative s evaluate di n thi s RO D Amendmen t fo r OU- 2 can b e easil

y implemented . Th e material s an dequipment

neede dfo r

maintenanc e o f

th e site , long-ter

mmonitoring , an doi l recover y ar e al l readily available . Th e VERsystemi s already installe dan dha s been operate di n thre e separat

e trial s spannin g severa

l months . Th e Restrictiv e Covenant i s currentl y i n place . I f additiona l institutional control s are needed , the y als o ca n b e readil y implemented . 7 . Cos t Thi s criterio n include s th e ne t presen t worth estimate s fo r

capita l (up-front ) an doperatio n an d maintenanc e cost s o f

implementin g eac h alternativ e evaluate dfo r OU-2 . Th e cost s describe d belo w d o no t

includ e previou s site-wid e cost s whic h wer e substantial . Th e cos t estimate s onl y reflec t thos e cost s tha t

woul db e incurre dhencefort h t o implemen t th e alternative s evaluated . Th e estimate dtota l presen t worth cost s associate dwith th e managemen t o f migratio n componen t i n th e 198 9 RO D wa s $679,00 0 wit h operatio n an dmaintenanc e cost s fo r thirt y year s comprisin g $631,00 0 o f

th e total . I n evaluatin g th e alternative s fo r costs , EP A note s tha t

th e ne t presen t worth ha s bee n calculate d fo r thirt y years , followin g EP A guidance , wherea s i t i s th e expectation o f

al l partie s tha t

th e cleanu p activitie s wil l las t considerabl y longer . Th e ne t presen t wort h o f Alternative s 1 an d2 are $622,00 0 an d$1,055,000 , respectively . 8 . State Acceptanc e Thi s criterio n addresse s whether , base do n it s revie w o f th e dat aderive dfro mth e sit e an dth e Propose d Plan , th e Stat

e concur s with , opposes , o r ha s n o commen t

o n th e amendmen t

tha t EP A ha s selecte d fo r

th e site . Main e DE P ha s reviewe dth e Jun e 200 2 Propose dPla n t o amen dth e 198 9 Cleanu p Pla n an da draf t o f thi s amendment . Th e Main e DE P concur s wit h th e remed y chang e wit h certai n conditions . Thes e condition s hav e bee n addressed . Th e Main e DE P ha s provide dalette r o f concurrenc e whic h i s provide di n Appendi x C . 9 . Communit y Acceptanc e Thi s criterio n addresse s whethe r th e publi c concur s with EPA' s propose dAmendment . Complianc e wit h thi s criterio n i s base do n th e comment s receive da t th e publi c meetin g an d publi c hearing . Base do n th e publi c informatio n an dpubli c hearin g meeting s an dcomment s receive ddurin g th e publi c commen t

period , i t appear s tha t

th e propose damendmen t ha s communit y support . 

### X . TH E SELECTE D REMED Y FO ROU- 2 3 6

### EP

A ha s selecte

d the remed

y describedbelo w a s the bes t balanc e betwee

n the nin e criteria . The selected remedy relie s o n institutional controls , activ e oi l recovery , an dlong-ter mmonitorin g o f overburde n an dbedrock

groundwater . Thi s remed y wa s selecte

dwithi n the context

o f the determinatio n b y EPA tha t i t i s technicall

y impracticabl e to restor

e th e groundwater

fo r alimite d portio n o f

th e Sit e withi n areasonable timeframe . Fo r th e amende dcleanup plan fo r OU-2 , EPA ha s selectedaremedy whic h ensure s protectivenes s o f

human healt

h an dth e environment , attain s al l federal an dstat e regulation s wit h th e exceptio n o f

waivin g drinkin g wate r

standard s fo r

aportio n o f

th e site , provide s long-term an dshort-termeffectiveness , i s implementable , an dreduce s toxicity , volume , an dmobilit y throug h treatment . Th e amende dcleanu p plan fo r OU- 2 includes : 1 . Institutional control s t o preven t exposure t o th e contaminate dgroundwate r

• I n 1994 , CM P an dMain e DEP signedaRestrictiv e Covenant o n aportio n o f

th e property whic h prevent s certai n activitie s withou t writte n approval fro mMain e DE P (se e Figur e 4) . Th e Covenant

require s CM P t o maintai n th e propert y t o ensure tha t

th e remedy remain s protective . Th e Covenan

t run s wit h th e lan dan di s bindin g o n al l futur e owners . Th e Restrictiv e Covenant

wa s recorde da

t th e Kennebe c County Registr y o f Deed s o n Septembe r 13 , 2002 . I f

th e Covenan t

i s release dprio r

t o th e completio n o f

th e remedy , o r

i f EP A find s that i t i s no t effectiv e an dprotective , EP A wil l requir e othe r institutional control s b e pu t i n plac e o n th e site . •A n operatio n an dmaintenanc e plan wil l b e implemente dt o ensur e tha t th e institutiona l control s are bein g followed , that the y are effectiv e an dprotective , an dtha t th e Site i s manage dproperly . Th e O& M plan will includ e aschedul e fo r monitorin g th e soi l cover , resurveyin g o f

th e designate darea , an dperiodi c samplin g an danalysi s to ensur e th e integrit

y o f th e soil cove

r ove r th e designate darea . Thi s samplin g wil l coincid e wit h th e five-yea r review s an dwil l consis t

o f alimite dnumbe r

o f soi l sample s collecte dfro mabou t 6- 8 inche s belo w th e groun dsurfac e an danalyze dfo r PCBs . 2 . A combinatio n o f

activ e an dpassiv e remova l o f the oi l an dassociatedPCB s

• A vacuum-enhance dpumpin g syste mwil l b e use dannuall y t o remov e oi l fro mth e groundwater . Thi s systemwil l b e operate do n a n annual basi s i n lat e summer - earl y fal l unti l i t i s determine dt o b e n o longe r effective . Criteri at o b e use dt o mak e thi s determinatio n includ e th e following :

appl y th e VE Rt o fou r

well s (101 , 202B , 310B , an d302B ) i n th e TW A I I are aa t leas t onc e ever

y yea r fo r th e nex t fiv e year s (2007) . Th e necessit y an dcondition s fo r continuatio n o f

th e VE Rwoul db e addresse ddurin g th e nex t fiv e 5-year review , schedule dfo r

Septembe r

2007 , an deac h subsequen t 5-yea r revie w period . Afte r applicatio n o f

th e VE Rt o awell , recover y o f oi l wil l b e observe dover

a 3 7perio do f u p t o on e week . I f a"significant " amount

o f oi l i s recovered fro mth e well , th e VERwil l b e reapplie dto th e well . A "significant " amoun t o f oi l wil l b e define da s a

n increas e i n th e amoun t

o f oi l recovere drelativ e to th e amoun t o f oi l recovere d throug h passiv e means . Basicall y thi s mean s tha t i f th e VE Ri s effectivel y increasin g th e amoun t o f oi l bein g recovere dfro mawell , i t wil l continu e o n tha t

well . •Th e operatio n o f

th e VE Rwil l continu e fo r aperio do f

u p t o tw o month s i f

significan t amount s o f

oi l ar e recovered . Afte r

thi s tim e weathe r

constraint s an drisin g groundwate r elevation s ar e expecte dt o limi t th e effectivenes s o f

th e VER . I t i s expecte dtha t

th e VE Rwil l b e operate dfo r th e nex t fiv e year s an dthi s determinatio n regardin g th e continue doperatio n o f th e VE Ra s part

o f thi s RO D Amendmen t

wil l b e mad e i n conjunctio n with th e nex t five-year revie w schedule dfo r

summe r 2007 . Thi s componen t

o f th e remed y require s placemen t o f absorbent

material s i n monitorin g well s afte r th e conclusio n o f

th e pumpin g t o absor

b an y remainin g residua l oil . Th e us e o f absorben t material s wil l continu e unti l a s lon g a s i t i s practical , i.e , a s lon g a s oi l i s visibl y detectable . Betwee n activ e operatio n o f th e VER , th e well s ar e currentl y monitore do n amonthl y basis . I t i s anticipate dtha t

thi s frequenc y wil l b e reduce dt o quarterl y i n th e future . Al l recovere doi l an d use dabsorben t

materia l wil l b e dispose do f at alicense dTS D facility . 3 . Monitorin g th e groundwate r t o demonstrat e tha t

th e contaminatio n i s no t expandin g an dtha t natura l processe s wil l continu e t o decreas e th e contaminan t concentrations .

• Thi s componen t

o f th e remed y require s implementatio n o f along-termgroundwate r monitorin g progra mt o trac k dissolve dPC B an dVOCs . Thi s progra mwil l b e amodificatio n o f th e curren t

monitorin g progra m

• I t wil l als o requir e trackin g th e progres s o f attenuatio n b y monitorin g dissolve d contaminan t

level s beyon dth e are awher e th e oi l i s presen t i n th e groundwater . Thi s monitorin g dat awil l b e use dt o verif y tha t th e dissolve dcontaminan t concentration s ar e decreasing . •Finall y thi s componen t

o f th e remed y wil l includ e contingencie s shoul dth e groundwate r monitorin g indicat e th e contaminatio n i s movin g beyon dit s curren t limits . Contingencie s ma y includ e increase dsamplin g frequency , implementatio n o f additiona l samplin g locations , includin g an y residentia l well s installe do n adjacen t properties , reevaluatio n o f th e conceptua l model , an dincrease doperatio n o f th e VER . 4 . Evaluatin g th e cleanu p approac h t o confir mtha t i t i s protectiv e o f

huma n healt h an dth e environmen t

3 8

### •A s long a s contaminatio n remain s which prevent s unrestricte dus e o f the site , the Superfun d law require s review s ever

y fiv e year s to evaluate th e effectivenes s o f th e implemente d cleanup plan . A s part

o f eac h fiv e yea r review , EPA will review the sit e condition s t

o determin e i f

the cleanu p actio n remain s protective , conside r ne w technologies , an drefin e the tim e estimate s necessar

y to reach th e groundwater standards . I n additio n t o thes e component s fo r OU-2 , monitorin g Rigg s Broo k fo r OU- 3 wil l continu e a s specifie di n th e 198 9 ROD , t o trac k change s i n PC B concentration s an dt o demonstrat e n o unacceptabl e impac t

o n sedimen

t qualit y o r

aquati c o r

terrestria l organisms . 

### X L STATUTOR Y DETERMINATION S Th e remedial actio n selecte dherei n fo r implementatio n fo r

O'Conno r

OU- 2 i s consisten t

wit h CERCLA and , t o th e exten t practicable , th e NCP . A . Th e Selecte dRemed y i s Protectiv e o f Huma n Healt h an dth e Environmen t Th e selected remedy wil l b e protectiv e o f huma n healt

h an dth e environment . Exposur e to contaminate dgroundwate r wil l b e prevente dthroug h th e Restrictiv e Covenan t o r othe r institutiona

l controls . Thi s Covenant

include s th e following :

• an y us e o f

th e groundwate r

beneath th e sit e i s prohibite dwithou t th e writte n approva l o f Main e DEP ;

• an y activit

y whic h migh

t disrup t remedial o r

monitorin g measure s i s prohibite dwithou t th e writte n approval o f

Main e DEP ; an d •CM P o r an y subsequen t

owne r shal l maintai n th e sit e i n aconditio n adequat e t o ensur e th e continue dcomplianc e wit h al l applicabl e standard s an dt o ensur e th e ongoin g adequac y o f th e remediation . I f othe r institutiona l control s ar e required , the y wil l ensur e th e protectivenes s o f th e remedy . Activ e recover y o f

PCB-oi l wil l decreas e th e mas s an dvolum e o f th e contaminant s o f

concer n a s wel l a s reduc e it s mobility . Long-termmonitorin g o f th e groundwate r

wil l allo w EP A t o trac k th e decreasin g concentration s presen t i n th e overburde n soil s an dbedroc k aquifer . Ther e ar e n o significan t short-termrisk s t o huma n health o r th e environmen t

durin g implementatio n o f th e selecte dremedy . Th e potential exposure o f site worker s an dare aresident s durin g th e annual oi l recovery wil l b e monitore dt o asses s potentia l release s t o th e ai r durin g cleanu p operations . A s activ e oi l recover y ha s bee n implemente da t th e sit e sinc e 1996 , it s continuatio n a s par t o f th e RO D Amendmen t

remed y i s no t

anticipate dt o pos e an y significan t risk s t o sit e worker s o r

are a residents . 3 9B . Th e Selecte d Remed y Attain s o r Appropriatel y Waive s ARAR s ARAR s fo r

th e sit e wer e identifie ddurin g th e developmen t o f th e 198 9 ROD . A s apart o f th e T I Evaluatio n process , arevie w o f current ARAR s wa s conducte dan di s summarize dbelow . Sectio n 300.43 0 (e ) o f

th e Nationa l Contingenc y Plan (NCP ) require s tha t on-sit e remedia l action s at CERCL A site s mus t

mee t ARAR s unde r

federa l o r

stat e environmenta l o r

facilit y sitin g law s unles s ther e ar e ground s fo r invokin g awaiver . A waive r i s require di f

ARAR s canno t b e achieved . Othe r

federa l an dstat e advisories , criteria , o r guidance , a s appropriat e (t o b e considere d- TBCs) , shoul db e considere di n formulatin g th e remedia l action . ARAR s ar e promulgated , enforceabl e federa l an dstat e environmenta l o r publi c health requirements . Ther

e are tw o categorie s o f

requirements , "applicable " an d"relevan t an d appropriate" . CERCL A doe s no t allo w aregulatio n t o b e considere da s bot h "applicable " an d "relevan t an dappropriate" . Thes e categorie s ar e definedbelow : Applicabl e Requirement s - Sectio n 300. 5 o f th e NC P define s applicabl e requirement s a s "thos e cleanu p standards , standard s o f control , an dothe r

substantiv e environmenta l protectio n requirements , criteria , o r

limitation s promulgate dunde r Federa l o r

Stat e la w tha t

specificall y addres s ahazardou s substance , pollutant , contaminant , remedia l action , location , o r othe r circumstanc e at

aCERCLA site" . Relevan t an dAppropriat e Requirement s - Sectio n 300. 5 o f th e NC P define s relevan t an d appropriat e requirement s a s "thos e cleanu p standards , standard s o f control , an dothe r

substantiv e environmental protectio n requirements , criteria , o r limitation s promulgate dunde r Federal o r State la w that , whil e no t

'applicable ' t o ahazardou s substance , pollutant , contaminant , remedial action , location , o r

othe r circumstanc e at

aCERCL A site , addres s problem s o r situation s sufficientl y simila

r t o thos e encountere da t

aCERCL A site tha t

thei r us e i s wel l suite dt o th e particula r site. " T o b e considere d(TBCs ) guideline s are non-promulgate dcriteria , advisories , an dguidanc e issue db y th e federal o r

stat e governments . Alon g with ARARs , TBC s may b e use dt o develo p interi mactio n limit s necessar y t o protec t

huma n health an dth e environment . ARAR s an dTBC s ar e divide dint o thre e categories : chemical-specific , location-specific , an d action-specific . Thi s sectio n briefl y summarize s th e mos t significan t

chemical , locatio n an d actio n specifi c ARAR s fo r th e remed y an didentifie s thos e fo r whic h atechnica l impracticabilit y waive r i s sough t Chemical-Specifi c ARAR s Chemical-Specifi c ARAR s ar e usuall y health

- o r risk-base dnumerica l value s o r methodologie s which , whe n applie dt o site-specifi c conditions , resul t i n th e determinatio n o f

numerica l value s tha t establis h th e acceptabl e amoun t o r concentration o f

achemical tha t

ma y b e foun din , o r 4 0discharge d to , th e ambient environment . Thes e requirement s d o no t conside r th e mixture o f chemicals . A summar

y o f chemica l specifi c ARAR s i s presente d in Table 6 . Th e federal Maximu mContaminant Level s (MCLs ) ar

e chemical-specifi c ARAR s tha t gover n th e qualit y o f drinkin g water

provide d b y publi c water supply . MCL s ar

e relevan t an d appropriate requirement s i n establishin g remediatio n goal s fo r groundwate r

a t th e site an dare ARAR s outsid e th e T I zone . The 1992 Stat

e o f Main e Maximu mExposur e Guideline s (MEGs ) ar

e chemical-specifi c ARAR s tha t ar e health-base dguideline s intende dt o determin e drinkin g wate r qualit y fo r

privat e residential wells . MEG s ar e relevan t an dappropriat e requirement s i n establishin g remediatio n goal s fo r groundwater

a t th e site . Main e MEG s wer e revise di n 2000 , bu t

hav e no t bee n promulgate dan dtherefore , th e 200 0 Main e MEG s are TBCs . Th e MCL s an dMEG s fo r whic h atechnica

l impracticabilit y waiver

wil ] appl y ar e note di n th e Tabl e 3 i n Sectio n VII I above . Location-Specifi c ARAR s Location-specifi c ARAR s ar e restriction s place do n th e concentration s o f hazardou s substances , o r th e conduc t

o f activitie s solel y becaus e the y are i n specifi c areas . Th e general type s o f location-specifi c ARAR s that appl y t o th e sit

e ar e briefl y describe dbelo w an dar e presente di n Tabl e 7 . Several federa l an dstat e ARAR s regulat e activitie s tha t may b e conducte di n wetland s an d floodplains . Regulation s governin g endangere dspecie s a t th e federa l an dstat

e level s woul dnee d t o b e considere dfo r

an y propose d on-site actions . Th e Main e Natura l Resource s Protectio n Ac t govern s activitie s that

may occu r

i n o r adjacen t t o wetland s o r

surfac e wate r

bodies . Th e Main e Site Locatio n Developmen t La w regulate s activitie s tha t ma y adversel y affec t

existin g lan duses , an dsceni c characte r

o r natura l resources , an dneed s t o b e considere di n th e implementatio n o f a n alternative . N o waive r o f location-specifi c ARAR s i s bein g sough t fo r th e technica

l impracticability evaluatio n fo r

th e Site . Action-Specifi c ARAR s Action-specifi c ARAR s ar e usuall y technology

- o r activity-base drequirement s o r limitation s o n action s take n wit h respec t t o hazardou s wastes . Thes e requirement s ar e generall y focuse do n action s take n t o remediate , handle , treat , transport , o r dispos e o f

hazardou s wastes . Thes e action

specifi c requirement s d o no t i n themselve s determin e th e remedia l alternative ; rathe r the y indicat e how aselecte dalternativ e mus t be implemented . The genera l type s of action-specifi c ARAR s tha t

appl y t o th e sit e ar e briefl y describe dbelo w an dar e presente di n Tabl e 8 . Th e Toxi c Substance s Contro l Ac t (TSCA ) regulate s th e marking , storage , disposa l an dcleanu p

4 1o f

spill s o f PCB s greate r

tha n 5 0 pp mPCBs . I n addition , th e Main e Hazardou s Wast e Management

Rule s als o regulate treatment , storag e an ddisposa l o f hazardou s wastes , includin g PCBs . Thes e regulation s woul dneedto b e i n th e implementatio n o f any alternativ e that

include s th e removal and/o r

treatmen t o f contaminate dgroundwate r an dresidual oil . N o waiver

fo r action-specifi c ARAR s i s bein g sough t fo r th e technical impracticability evaluatio n fo r

th e Site . C . Th e Selecte dRemedia l Actio n i s Cost-Effectiv e Th e selecte dremed y i s cost-effectiv e sinc e i t provide s overal l effectivenes s proportiona l t o it s cost . Th e projecte dne t

worth cost s ove

r thirty year s fo r

th e tw o amendmen t

alternative s evaluate d wer e $0.62 2 millio n fo r

Alternativ e 1 an d$1.05 5 millio n fo r Alternativ e 2 . Th e selecte dremed y Alternativ e 2 activel y remove s contaminatio n throug h treatmen t fro mth e groundwate r

wherea s Alternativ e 1 doe s no t

includ e activ e removal . Additionally , EP A believe s th e actua l cos t differenc e fo r

th e tw o alternative s i s no t a s grea t at i t appears . Thes e cost s hav e bee n calculate d base do n thirt y years , ye t i t i s anticipate dthat

th e long-termmonitorin g fo r OU- 2 wil l continu e considerabl y longer . However , b y activel y removin g th e oi l o n an annua l basi s a s lon g a s i t i s practical , EP A expect s thi s wil l shorte n th e tim e perio dfo r groundwate r

restoratio n an dthereb y requir e les s long-termmonitorin g compare dt o Alternativ e 1 . D . Th e Selecte dRemed y Doe s Utiliz e Permanen t Solution s an dAlternativ e Treatmen t o r Resourc e Recover

y Technologie s t o th e Maximu mExten t Practicabl e Th e selecte dremed y provide s apermanen t solutio n an dalternativ e treatmen t o r resourc e recovery technologie s t o th e maximu mexten t practicabl e fo r

th e separat e phas e oi l throug h activ e oi l recovery . Throug h institutiona l controls , th e groundwate r i s isolate dfro mhuma n us e an dthu s prevent s exposur e Extrapolation s o f groundwate r

monitorin g dat adowngradien t o f th e T I zon e indicat e tha t

th e groundwate r

beyon dth e T I zon e wil l attai n th e cleanu p standard s withi n th e nex t te n years . Throug h th e activ e recovery o f oi l o n a n annual basis , th e selecte dremed y reduce s th e mas s o f contaminatio n mor e quickl y tha n natura l attenuatio n processes . Followin g th e complete dSCRA , th e activ e oi l recover y seek s t o permanentl y furthe r reduc e th e sourc e o f

contaminatio n fo r

th e downgradien t

groundwate r

an dRigg s Brook . E . Th e Selecte dRemed y Doe s Satisf y th e Preferenc e fo r

Treatmen t

a s aPrincipl e Elemen t Th e selecte dremed y doe s us e treatmen t o f th e PC B oil-contaminate dgroundwate r a s aprincipl e elemen t o f th e remedy . Th e recovere doi l i s transporte doffsit e t o alicense dTS D facility .

4 2

### F . Fiv e Yea r Review s Becaus e thi s amendment

woul dresult

i n contaminant s remainin g onsite , EPA will review the sit e a t least onc e ever

y fiv e year s afte r

th e initiatio n o f

th e remedia

l actio n a t th e sit e to assur e tha t th e remedia l actio n continue s t

o b e protectiv e o f

human healt

h an dthe environment . Thi s review will b e consisten

t wit h th e CERGL

A §121(c ) applicabl e fo r

five-yea r sit e review s i n effec t

a t th e time o f th e review . Th e firs t

five-yea r review for

th e sit e wa s triggere db y th e star t o f th e sourc e contro l remedia l actio n an dwa s complete di n September 2002 . 

### XII . DOCUMENTATIO N O F N O SIGNIFICAN T CHANGE S Th e Propose dPla

n t o amen dth e 198 9 ROD , a s i t pertaine dt o th e MOM , wa s release dfo r publi c comment i n Jun e 2002 . Th e propose dchang e call s fo r attainin g protectivenes s o f huma n healt

h throug h institutiona l control s an dlong-ter mmonitorin g rathe r

than attainin g protectivenes s o f huma n healt

h throug h restoratio n o f

th e sit e groun dwate r

throug h activ e remedial action . Th e amende dcleanup plan doe s includ e activ e recovery o f th e PC B laden-oil , thereb y providin g treatment a s acomponen

t o f th e remedy . EP A determine dthat , base do n comment s receive ddurin g th e publi c commen t perio dwhic h conclude do n Jul y 19 , 2002 , n o significan t chang e i s neede dt o th e propose damende dcleanu p plan . EP A ha s prepare daresponsivenes s summary t o addres s th e comment s receive ddurin g th e publi c comment

period . Th e responsivenes s summary i s attache da s Appendi x A . 

### XIII . STATE ROL E Th e Main e Departmen t

o f Environmental Protectio n ha s reviewe dth e remedy chang e an d concur s wit

h th e selectedremedy describe di n Sectio n X o f thi s Amendment . A cop y o f th e Stat e concurrenc e lette r

i s attache da s Appendi x C .

4 3

### Septembe r 200 2 RO D Amendmen t F . O'Conno r

Superfun dSit

e Tabl e 1 : Compariso n betwee n 198 9 RO D an d200 2 RO D Amendmen t 198 9 RO D - Groundwate r component s #1 : temporary institutiona l controls . Thi s woul dprevent

exposur e t o site groundwate r whil e remediatio n wa s underway . #2 : pump-and-trea

t system . Th e appropriat e sizing o f th e system , includin g th e numbe r o f extractio n wells , pumpin g rate , treatment component s suc h a s granula r activate dcarbon , san dfilters , air

stripper , an dnumbe r

o f recharg e well s wa s to b e determine ddurin g th e remedia l desig n phase . #3 : anetwor

k o f monitorin g wells . Th e well s use di n th e R

l woul db e assesse

d an daugmente d wit h additiona

l well s i n bot

h overburde n soi l an dbedrock . #4 : Rigg s Broo k

sedimen t an dbiot amonitoring . Broo k sediment s wer

e to b e monitore dyearl y fo r te n year s to asses s PC B concentrations . Biotasamplin g wa s to occu r fiv e year s afte r initiatio n o f

th e monitoring . #5 : five-yea r

reviews . Tli e progres s towar d restoratio n o f

th e sit e groundwate r

an dth e targe t clea n u p goa l fo r th e sedimen

t were t o b e assessed durin g each five-yea r review . 

### 200 2 RO D Amendmen t fo r OU- 2 # 1 permanen t

institutional controls . Wit h th e 199 4 BSD , CM P an dMain e DE P signe da restrictiv e covenan

t whic h prevente dcertai n activitie s a

t th e sh e withou t

writte n approval o f Main e DEP . #2 : annua l applicatio n o f

th e VE Rsystem . Th e VERha s bee

n operate dthre e time s post-ROD , recovering PCB-laden oi l fro mth e overburde n an dbedrock . Th e VE Rwil l b e applie dannuall y i n TW A II are awell s to recove r a s muc h oi l a s i s practical . # 3 monthl y monitorin g o f oi l level s i n TWA I I well s an dremova

l usin g absorbent

materials . Betwee n th e annua

l operation s o f

th e VER , th e TW A I I wil l b e monitore dfo r separate phas e oil . Detecte doi l will b e remove dusin g absorbent material . It

i s expectedthat monitorin g frequenc y will decreas e a s the amount o f oi l drainin g into th e well s decreases . #4:long-ter mmonitoring . I t wil l b e performe d t o trac k contaminan t

level s i n th e T l zon e an d outsid e it . #5 : Rigg s Broo k

sedimen t an dbiot amonitoring . I t wil l continu e a s OU-3 , establishe di n 199 6 #6 : five-yea r

review s Review s wil l b e conducte dt o ensur e tha t

th e sit e remed y fo r

al l thre e OU' s remain s protective .September 2002 RO D Amendmen t F . O'Conno r

Superftin dSit

e Tabl e 2 : PC B Result s - TW A I I

Samplin g Dat e OW

202 B 3/9 8 6/9 8 9/9 8 12/9 8 3/9 9 6/9 9 9/9 9 3/0 0 9/0 0 4/0 1 9/0 1 N D

N D N S N D 0.7 9 N S N S N S N S 0.3 5 N S FC B Result s (/fg/L ) - TWA 1 1 RO D Cleanu p Standar d0. 5 /zg/L OW

- OW

- OW

- RW-10 1 204 B 30 1 B 302 B N D N D 0.6 4 Jl. O N D 1.1 7 N S N S 0.6 2 N D N S 5. 6

1. 2 1. 7 7. 1 3. 1 2. 9 N S N S 8. 6 3. 5 N S 2. 5

3 2 1,50 0 8,90 0 93 0 71 0 N S N S 8. 6 4 4 N S 2. 3

1. 5 N S N S 2.3 2 N S N S N S N S 0.1 2 N S Numbe r

o f Exceedance s 3 3 5 - 4 4 5 5 5 5 2 5

N D - no n detecte dabov e PQL s N S - no t sample ddu e to presenc e o f oi l i n wel l (considereda

n exceedance) J - estimate du e t o th e percen t differenc e o f

continuin g calibratio n greate r tha n 15% . Bol d- RO D exceedanc eSeptember 2002 RO D Amendmen t F . O'Conno r

Superfun dSit

e Tabl e 3 : Chemical-Specifi c ARAR s fo r T I Waive r Contaminan t O f Concern Benzen e Chlorobenzen e 1 ,2- D ichlorobenzen e 1 ,3-Dicblorobenzen e 1,4

- Dichlorobenzen e 1,2,3

- Trichlorobenzen e 1,2,4

- Trichlorobenzen e 1,3,5

- Trichlorobenzen e PCBs 1 200 1 Maximu m

Groundwate r Concentratio n (//g/L ) an dLocatio n 8 - OW-302B 24 0 - OW-302 B 21 0 - OW-302B 16 0 - OW-302B 72 0 - OW-302B 9 8 - OW-302B 77 0 - OW-302 B no t analyze dfo r 4 4 . QW-302 B MC L

(/^g/L )

5 10 0 60 0 

## n s 7 5 N S 7 0 N S 0. 5 199 2 ME G 0/g/L ) 5 4 7 8 5 8 5 2 7 N S 7 0 4 0 0.0 5 198 9 RO D Targe t

Cleanu p Level s (/^g/L ) 5 n o RO D standar d n o RO D standar d n o RO D standar d 2 7 n o RO D standar d n o RO D standar d n o RO D standar d 0. 5 1 detectio n limi t

varie s with locatio n an dare generall y greater than th e 199 2 MEG . N S - n o standardSeptembe r 2002 RO D Amendmen t F . O'Conno r

Superfun dSit

e Tabl e 4 : Gallon s o f

Oi l Recovere dFro mTWA I I Are aWell s Perio d Pum p Tes t

- VE R VE RPhase s I & I I Sourc e Contro l Passiv e Collectio n VE RPhas e II I Pos t VE RPhas e II I Tota l 1992-1994

1996-1997 1997 1997-200 1 200 1 2001-200 2 OW

202B 15. 8 0. 0 0. 0 2. 1 1. 9 0. 1 19. 9 

# ow 204 B 0. 0 0. 0 0. 0 0. 1 0. 0 0. 0 0. 1 OW

301 B 8. 3 0. 0 0. 0 0. 2 4. 6 0. 0 13. 1 OW-302B

5. 7 0. 0 0. 0 2. 3 10. 1 1. 7 19. 8 RW

10 1

— 26. 6 N A 2. 4 3. 2 0. 1 32. 3 Tota l

29. 8 26. 6 0. 0 7. 1 19. 8 1.9 85. 2Septembe r 200 2 RO D Amendmen t F . O'Conno r

Superfim dSit

e Tabl e 5 : Summar y o f

Groundwate r

Monitorin g Result s Modifie dMetho d68 0 Analyte s Total Mon o C B Total DiC B Total TriC B Total TetraC B Total PentaC B Total HextaC B Total HeptaC B Total OctaC B Total NonaC B DecaC B (#209 ) Total PC B Tota l PC B & EMP C MW

10 6 A fog/L) N D N D N D N D N D N D N D N D N D N D N/ A N/ A MW-106B

fcg/L) 0.00 4 0.0 1 0.0 1 0.02 N D N D N D N D N D N D 0.0 5 0.0 5 MW-50 3

fczg/L) 0.00 4 0.0 3 0.0 2 N D N D N D N D N D N D N D 0.0 6 0.0 9 MW-508 B

fcg/L) 0.00 8 0.0 1 N D N D N D N D N D N D N D N D 0.0 2 0.0 2 MW-104 B

(Mg/L ) EMPC * 0.04 N D N D N D N D N D N D N D N D 0.04 0.0 7 OW-201 B

fcg/L) 0 0.05 N D N D N D N D N D N D N D N D 0.0 6 0.0 7 Notes : EMP C - Estimate dMaximu mPossibl e Concentratio n * - EMPC-0.0 3

### Tabl e 6 : Identificatio n o f Chemical-Specifi c ARAR s ;^; <; 

### ; ;

r 

### , - BEQ0IRE&JEH

T X ^l;li>|f

;

### v " - * ! 

### ' s^.SK&i^^,- " " " GROUNDWATER Federa l Regulatory Requirement s SDW A - Sectio n 141 2 -MCL s (4 0 CF R 141.11-141.6 ) SDWA

- Sectio n 141 2 -MCLG s (4 0 CF R 141.50-141.51 ) CW A - Sectio n 304(a ) AWQ C

USEP A Ris k

Referenc e Dose s (RfDs ) USEP A Carcinoge n Assessment Grou p Carcinogeni c Potenc y Factor s (CPFs ) USEP A Healt

h Advisorie s (HAs )

U.S . Environmenta

l Protectio n Agenc y (USEPA ) Ris k

Referenc e Dose s (RfDs ) ^ : * 

### "V ^ s f

,'!*; . •• > " : " • • •. ' SV ^ Relevan t an d Appropriat e Relevan t an d Appropriat e Relevan t an d Appropriat e

T o b e considere d T o b e considere d T o b e considere d

T o b e considere d 

### \MQXBIUi^INTS^HOPSl S ;



## '"<• • ">/!'* * ' ' <-"- " ' - : , ; ^ MCL s hav e bee n promulgate dfo r severa l commo n organi c an dinorgani c contaminants . Thes e level s regulate th e concentratio n o f contaminant s i n publi c drinkin g water

supplies , bu t

ma y als o b e considere drelevant an dappropriat

e fo r groundwate r

aquifer s use dfo r

drinkin g water . MCLG s are health-base dcriteri aestablishe dfo r anumbe r

o f organi c an d inorgani c contaminant s a s water qualit y goal s fo r

drinkin g wate

r supplies . Thes e goal s ma

y als o b e considere drelevan t an dappropriate fo r

groundwate

r aquifer s use dfo r

drinkin g water . Federal AWQ C includ e (1 ) health-base dcriteri adevelope dfo r 9 5 carcinogenic an dnoncarcinogeni c compound s an d (2 ) othe r wate r qualit y parameter s | protectiv e o f

fis h an daquati c life . AWQ C fo r th e protectio n o f

human healt

h | j provid e level s fo r

exposure fro mdrinkin g wate r an dconsumin g aquati c organisms , an dfro mconsumin g fis h alone . Remedia l action s involving contaminate dsurfac e wate r o r groundwater

mus t conside r th e use s o f

th e wate r an dth e circumstance s o f th e releas e o r

threatene drelease ; thi s determine s whether AWQ C are relevant

an dappropriate . RfD s are considere dth e level s unlikel y t o caus e significan t advers e healt

h effect s associate dwit

h aLhreshol dmechanis mo f action i n human exposur

e fo r alifetime . Carcinogeni c effect s presen t th e mos t

up-to-date informatio n o n cance r ris k potenc y derive dfro mUSEPA' s Carcinogen Assessment Group . HA s ar e issue da s non-regulator y guidance . H A value s represent th e concentratio n o f

contaminant s i n drinkin g water a t whic h advers e healt

h effect s woul dno t b e expecte dt o occur . HA s ar e establishe dfo r one-da y an dten-da

y exposur e durations . RfD s ar e an estimate o f adail y exposur e concentratio n that i s likely t o b e withou t appreciabl e ris k

o f deleteriou s effect s durin g alifetim e exposure .State o f

Main e Regulator y Requirement s Main e Standard s fo r

Classificatio n o f Groundwate r

(3 8 M.R.S.A. , Chapte r

3 , Sectio n 470 ) Applicabl e Groundwate r i s classifie dunde r

th e Main e Standards . Th e groundwater a t th e O'Conno r Site i s classifie da s GW- A (i.e. , wate r shal l b e o f

suc h qualit

y tha t i t ca n b e use dfo r

domesti c purposes . Main e Drinkin g Wate r

Rule s (10-144 A CM RChapter s 231-233 ) Relevan t an d Appropriat e Maine' s Primar y Drinkin g Wate r Standard s ar e equivalen t

t o federal MCLs . 199 2 Main e Maximu mExposur e Guideline s (MEGs ) Relevan t an d Appropriat e MEG s ar e th e Burea u o f Health' s recommendation s fo r concentration s o f chemica l contaminant s i n drinkin g water . MEG s are health-base dguideline s an dare no t

legally enforceable . 200 0 Main e Maximu mExposur e Guideline s (MEGs ) T o b e considere d MEG s ar e th e Burea u o f Health' s mos t

recen t recommendation s fo r concentration s o f

chemica l contaminant s i n drinkin g water . MEG s ar e health

base dguideline s an dare no t legally enforceable .

### TABL E 7 : IDENTIFICATIO N O FLOCATION-SPECIFI C ARAR s

,. ; 

### ; ^ . KE< 

### * nBW1 T 

### g 

# -^mw^^^f^^^i^f^ ^ ^ Federa l Regulatory Requirement s National Environmental Polic y Ac t (NEPA , 4 2 US C § 4341 ) an dWetlan d Executiv e Orde r

(EO11990) , 4 0 CF R Par t 6 , Appendi x A Nationa l Histori c Preservatio n Act(NHPA , 16 USC 470 etseq. . 40 CFR 800 ) Clea n Wate r

Ac t Sectio n 40 4 Requirement s fo r

Dredge do r

Fil l Materia l (3 3 US C 1344 ; 4 0 CF R230 ) Stat e o f Main e Regulatory Requirement s Maine Natura l Resource s Protectio n Ac t (NRPA , 3 8 MRS A § 480 ) an dPermi t B y Rul e Standard s (MEDE P Regulation s Ch . 30 5 

# & ••

• ^i ^ V K * "~ws*"- » Applicabl e Applicabl e (i f encountered ) Applicabl e

Applicabl e Th e Wetland s Executiv e Orde r require s federa l agencie s t o mimmiz e th e destruction , loss , o r

degradatio n o f

wetlands , an dpreserv e an denhanc e natural an dbeneficia

l value s o f

wetlands . CERCL A respons e action s are require dto consider possibl e effect s o f

th e respons e activitie s o n any histori c property include di n o r eligibl e to b e include d i n th e National Registe

r o f Histori c Places . Unde r thi s requirement , n o activit y that adversel y affect s awetlan dshall b e 1 permitte di f

apracticabl e alternativ e i s available . |

Thi s ac t outline s requirement s an dperformanc e standard s fo r certain activitie s in , on , over , o r

adjacen t to freshwate r

wetlands , streams , ponds , o r brooks . Th e activitie s mus t

no t unreasonabl y interfere wit h certai n natural features , such a s natural flo w o r

qualit y o f an y waters , no r

har msignificant

aquati c habitat , freshwate r fisheries , o r

othe r aquati c life .vlain e Endangere dSpecie s Ac t an d Regulation s (1 2 MRS A Sectio n 7751

- 7756 ; 09-13 7 CM R008 )

Wi^^^i^iiAl^M^IS^ ^ •••:;- • Federa l Regulatory Requirement s Endangere dSpecie s Ac t

(ESA , 1 6 US C § § 1531-1534 ) Stat e o f Main e Regulator y Requirement s Main e Standard s fo r

Classificatio n o f Groundwate r

(3 8 MRSA , § § 46 5 - C an d 470 )

Main e Endangere dSpecie s Ac t (MESA , 3 8 MRS A § § 7001 , 7751-7759 ) an d Main e Inlan dFisherie s an dWildlif e Law s an dRegulation s (1 2 MRS A § 70 3 1 et seq. ) Applicabl e (i f endangere dspecie s ar e identifie do r encountered )

'••: • ':' : ;t:te:d-; : Applicabl e (i f encountered ) Applicabl e

Applicabl e (i f encountered ) Th e stat e o f Main e ha s th e authorit

y t o research , list , an dprotec t an y specie s that ar e determine dt o b e threatene do r endangered , accordin g t o stat e regulations . Th e M E Departmen t

o f Inlan dFisherie s an dWildlif e ha s develope dth e followin g categorie s fo r th e consideratio n o f

importan t

specie s tha

t no t threatene do r

endangered : Main e Watc h List , Special Concer n List , an d Indeterminat e Category . Th e departmen t determine s habita

t use s o n acase-by

cas e basis . Th e Main e list s o f specie s ma

y diffe r fro mth e federal . ! tx-;/ : •:;Mli;&^ Thi s ac t require s action t

o avoi djeopardizin g the continue dexistenc e o f liste d endangere do r

threatene dspecie s o r

notificatio n o f

thei r habitat .

Thi s la w establishe s th e classificatio n o f th e -state' s groundwate r t o protect , conserve , an dmaintai n groundwate r resource s i n th e interes t o f th e health , safety , an dgenera l welfar e o f th e peopl e o f

th e state . Groundwate r

i s classifie d a s GW-A , th e highes t groundwate r

classification , an di s designate da s a potentia l wate r

supply . Thi s classificatio n applicabl e t o remedial objectives . Th e Stat e o f Main e ha s authorit

y to research , list , an dprotec t any specie s deeme dendangere do r

threatened . Thes e specie s are liste da s eithe r endangere d o r threatene di n th e stat

e regulations . Th e Main e Departmen t o f Inlan dFisherie s an dWildlif

e ha s als o develope dth e followin g administrativ e categorie s fo r specie s no t

considere dendangere do r threatene dbu t

considere dimportant

fo r researc h an dfurthe r

evaluation : Main e Watc h List , Special Concer n List , an d Indeterminat e Category . Th e Departmen t determine s appropriate use(s ) o f variou s habitat s o n acase-by-case

- basis . Th e Main e list s may diffe r fro mth e federa l list s o f

endangere dspecies . {Maine Sit e Locatio n an dDevelopmen t La w an dRegulation s (3 8 MR S A Section s 48 1 throug h 490 ; MEDE P Regs . Ch . 371-377 ) Applicabl e Thi s ac t an dregulation s gover

n ne w development , includin g ne w development s that handl e hazardou s waste s an doil . Activitie s cannot adversely affec t

existing uses , sceni c character , o r natura l resource s i n th e municipalit y o r neighborin g municipality . vlain e Critical Area s Progra man dMain e Natura l Heritag e Progra m T o B e considere d Thes e stat e program s issu e policie s an dregulation s governin g specia l habitat s o r communities . Main e Critical Area s Ac t ( 5 MR S A § § 3310-3316 ) T o B e considere d Thi s non-regulator y legislatio n allow s Main e agencie s suc h a s th e Critica l Area s Progra man dth e Natura l Heritag e Area s Progra mto identify , research , an d protec t critica l area s an dendangere do r threatene dplants . Municipa l Regulator y Requirement s Mandator y Shorelan dZonin g (3 8 MR S A § § 435-449 ) Tow n Shorelan dZonin g Ordinance s an d Stat e Minimu mGuideline s (3 8 MR S A § § 1801-1803,1841-1843-A , 1901-1905 , 2013 ) an dCit y o f August a Comprehensiv e Plan/Shorelan dZonin g Plan T o B e considere d Thes e minimu mguideline s an dtow n ordinance s appl y t o activitie s propose d withi n 25 0 fee t

o f ahigh-water

mark o f astrea mo r othe r body o f water .

### TABL E 8 : IDENTIFICATIO N O FACTION-SPECIFI C ARAR s

Federa l Regulator

y Requirement s TSC A (1 5 US C § § 2601-2692 ) an d Polychlorinate dBiphenyl s (PCBs ) Regulation s (4 0 CF R761 : Subpar t

G , PC B Cleanu p Policy ; an dSubpar

t C an dD , Markings , Storag e an d Disposal ) Thes e requirement s appl y t o th e marking , storage , disposal , an dcleanu p o f PCB s greate

r than 5 0 pp mtha t occur afte r thei r respectiv e effectiv e dates . Th e PC B Spil l Cleanup Policy , Subpart , applie s t o spill s o f

PC B greate r

tha n 5 0 pp mthat

occurre dafte r

it s effectiv e dat e (i.e. , Ma y 4 , 1987) . U.S . Departmen t

o f Transportatio n Rule s fo r Transportatio n o f

Hazardou s Material s (4 9 C.F.R . Part s 107 , 171.1-172.558 ) Thi s regulatio n outline s procedure s fo r th e packaging , labeling , manifesting , an dtransportatio n o f hazardou s materials . I f

residual s fro mgroundwate r treatmen t and/o r recovere dfre e produc t ar e classifie da s hazardous , th e material s wil l b e packaged , manifested , an dtransporte dt o a license doff-sit e disposa

l facility i n complianc e wit h thes e regulations . USEP A RCR A - Standard s Applicabl e t o Generator s o f

Hazardou s Wast e (4 0 CF RPar t 262 ) Thi s requiremen t set s standard s fo r

generator s o f

hazardou s wast e tha t

addres s (1 ) accumulatin g waste , (2 ) preparin g hazardou s wast e fo r shipment , an d(3 ) preparin g th e unifor mhazardou s wast e manifest . Thes e requirement s ar e integrate dwit h DO T regulations . An y RCR A hazardou s waste s bein g shippe doff-sit e mus t b e shippe di n prope r

container s that

ar e accuratel y marke dan d labeled , an dth e transporte r mus t display prope r

placards . Al l wast e shipment s mus t b e accompanie db y a n appropriate manifest . USEP A RCR A - Standar dApplicabl e t o Transporter s of

Hazardou s Wast e (40 CFRPart 263 ) Thes e regulation s outlin e th e standard s fo r transportatio n o f

hazardou s wast

e off-she . Transporter s o f

hazardou s wast e mus t

compl y wit

h manifest , recor dkeeping , an dreportin g requirement s se t

fort h i n thes e rules . Thes e requirement s wil l b e attaine dthroug h complianc e wit h U.S . DO T Rule s fo r

Transportatio n o f

Hazardou s Waste .USEP A Guidanc e fo r Evaluatin g Technica

l Impracticabilit y o f

Groundwate r

Restoratio n (9234.2-25) . Consisten t Implementatio n o f

the F Y 199 3 Guidanc e o n Technical Impracticability o f Groundwate r

Restoratio n at

Superfun dSite s (9200.4-14 ) Us e o f Monitore dNatura l Attenuatio n at Superfund , RCR A Correctiv e Action , an dUS T Site s (9200 . 4

- 17P ) Overvie w o f

ARARs , focu s o n ARA RWaiver s (OSWER9234.2-03/FS ) Thi s guidanc e clarifie s ho w USEP A wil l determin e whethe r groundwate r

restoratio n i s technicall

y impracticabl e an dwha t

alternativ e measure s o r

action s mus t

b e undertake n t o ensur

e tha t th e final remedy i s protectiv e o f

huma n healt

h an dth e environment . Thi s memorandu moutline s the basi c proces s for evaluatin g a

t Tl decisio

n documen

t an di s intende dt o promot e technicall y sound , nationall y consistent implementatio n o f

th e T l guidance . Thi s directiv e clarifie s ERA' s polic y regardin g th e us e o f monitore dnatural attenuatio n fo r th e cleanu p o f

contaminate dsoi l an dgroundwate r i n th e Superfun dprogra m(among others) . Thi s memorandu mprovide s an overvie w o f ARARs , wit

h afocu s o n ARA Rwaivers . Stat e o f Main e Regulatory Requirement s Wast e Discharg e License s (3 8 M.R.S.A . § 413 ) Main e Hazardou s Waste , Septage , an dSoli d Waste Management

Ac t Titl e 38 , Chapte r

1 3 an dMEDE P Regulations , Chapter s 800-802 , 850 . 851.853-857 1 ) Direc t o r indirec t discharge s t o th e water s o f th e stat e requir e alicense . Th e rule s provid e acomprehensiv e programfo r handling , storage , an drecordkeepin g a t hazardou s waste facilities . The y supplemen t th e RCR A regulations .^..j-e—Uaa ^ .'/• ' ' V / - ^ 

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TOGU S POND . MAIN E 7. 5 MIN . SERIES . 198 8 LAN D INF O INTERNATIONAL , LTD . 250 0 500 0 FEE T



### WOODAR D & CURRA N SIT E LOCATIO N MA P

DfSiCNf D B Y if M UHAW N 6V J6C CITC'C C 8 Y LC U CENTRA L MAJN F AUGUSTA . MAIN E O'CONNO R COMPAN Y SUPERFUN D SIT E JO B N O ?0562 I 0 3 5C«L f « S NOTE D FIGUR E 1

### APPENDI X I I T O AMENDMEN T T O O'CONNO RCONSEN T DECRE E REMEDIA L DESIGN/REMEDIAL ACTIO N 200 3 STATEMEN T O F WOR K A . Introductio n an dPurpos e o f Pla n I t i s th e purpos e o f

thi s Remedia l Design/Remedia l Actio n 200 3 Statemen t o f Wor k (200 3 SOW ) t o defin e th e remedia l action s t o b e undertake n an dfunde db y th e Settlin g Defendan t unde r th e Amendmen t

t o Consen t

Decre e a t

th e O'Conno r

Sit e i n Augusta , Maine . Th e SO W describe s th e exten t

o f remedial activitie s require da t th e Site base do n th e September 200 2 Recor do f Decisio n Amendmen t

(RO D Amendment ) an dsamplin g result s availabl e t o EP A a s o f Septembe r

2002 . Thi s Appendi x I I supersede s Appendi x I I o f th e Septembe r

3 , 199 1 Consen t Decree , a s amende di n th e 199 4 revise dSO W (199 4 RSOW ) followin g th e Jul y 11 , 199 4 Explanatio n o f

Significan t

Differences . Th e 200 3 SO W follow s th e sam e forma t a s th e 199 1 SO W an d199 4 RSOW . Th e remedia l action s describe di n thi s Appendi x I I includ e element s whic h hav e bee n complete d pursuan t t o th e 199 1 Consen t

Decre e (sourc e contro l components , managemen t o f migratio n components , Rigg s Broo k components , an dinstitutiona l controls) ; element s whic h ar e carrie d forwar dfro mth e 199 4 RSO W (sourc e contro l an dRigg s Broo k components) ; an dthos e remedia l action s tha t

th e Settlin g Defendan t

ha s consente dt o undertak e pursuan t t o thi s amende d settlemen t agreemen t

(managemen t

o f migratio n components) . Par t B o f thi s SO W provide s definition s o f term s use di n thi s Appendix . Par t C provide s a n updat e o f activitie s sinc e th e 199 4 RSO W an da n overvie w o f th e Remedia l Actio n selecte dfo r th e Site . Part s D . E . F . an dG o f thi s SO W describ e an dupdat e eac h o f th e remedia l component s fo r remediatio n tha t

\\er e require db \th e 1 ^9 1 SO Wan d199 4 RSOW : contaminate don-sil e surfac e waters , contaminate don-sit e soil s an dsediments , contaminate dgroundwater , an dRigg s Brook . Part s H , I , J , an dK o f thi s SO W describ e furthe r requirement s an dprocedure s fo r sit e acces s an dinstitutiona l controls , remedia l design , remedia l action , an doperatio n an d maintenance . B . Definition s Th e followin g definition s shal l appl y t o thi s SOW . Grounduaie r

performanc e standard s shal l mea n thos e uroundwate r performanc e standard s specifie di n th e RO D Amendment : Benzene : 5 ug/ L (sam e a s th e 198 9 ROD ) 1.4

- Dichlorobenzene : 2 7 ug/ L (sam e a s th e 198 9 ROD ) 1

### PCBs' : 0.0 5 ug/L (th e 198 9 RO D performanc e standar dwa s 0. 5 ng/L )

Chlorobenzene : 4 7 u,g/

L (there wa s n o performanc e standardfo r thi s i n th e 198 9 ROD ) 1,2-Dichlorobenzene : 8 5 ng/ L (there wa s n o performanc e standardfo r thi s i n th e 198 9 ROD ) 1,3-Dichlorobenzene : 8 5 ^g/ L (ther e wa s n o performanc e standar dfo r thi s i n th e 198 9 ROD ) 1,2,4-Trichlorobenzene : 7 0 u.g/ L (ther e wa s n o performanc e standar dfo r thi s i n th e 198 9 ROD ) 1,3,5-Trichlorobenzene : 4 0 (jg/ L (there wa s n o performanc e standardfo r thi s i n th e 198 9 ROD ) 1 

### detectio n limi t

varie s wit h locatio n an di s generall y greate r tha n th e 0.0 5 u.g/L . "Activ e Oi l Recovery " shal l mean th e us e o f vacuum-enhance dpumpin g fro mwell s locate d withi n th e Technica l Impracticabilit y Zone . Th e inten t o f th e activ e oi l recover y effor t i s t o remov e separate-phas e oi l tha t i s locate do r

ha s com e t o b e locate dabov e th e seasonabl e wate r tabl e i n th e overburde n an dbedroc k withou t removin g groundwater . "Passiv e Oi l Recovery " shal l mea n th e us e o f absorben t material s place dwithi n extractio n an d monitorin g well s withi n th e T I zone . Th e inten t o f th e passiv e oi l recover y i s t o remov e separate phas e oi l tha t

i s locate do r

ha s com e t o b e locate dabov e th e seasonabl e wate r tabl e i n th e overburde n an dbedrock

between period s o f

activ e oi l recovery . C . Remedia l Actio n Overvie w Th e remed y selecte db y th e 198 9 RO D wa s develope dt o satisf y th e followin g fiv e remedia l actio n objective s (RAOs) : •reduc e publi c healt h an denvironmenta l risk s fro mdirec t contac t wit h contaminate d soils , •reduc e publi c health'risk s fro minhalation s o f PC B vapors . •reduc e futur e healt h risk s fro mingestio n o f contaminate dgroundwate r foun do n ili e MIC . •reduc e publi c healt h risk s fro mingestio n o f PCB-contaminate dfis h fro mRigg s Brook , an d 

### •reduc e risk s t o aquati c an dterrestria l wildlif e fro mexposur e t o contaminate dsediments . Th e 199 4 ES D modifie dth e selecte dsourc e contro l remed y i n thre e aspects : redefinitio n o f th e Sit e t o includ e 2 3 acre s o f th e parcel : chang e o f

th e cleanu p standard s fo r PCB s fro mon e pp mt o te n pp mfo r

adesignate dare aonsit e wit h concurren t requiremen t

o f regradin g th e designate d are awit h twelv e inche s o f clea n fil l abov e th e consolidate dsoils ; an dacontingenc y cleanu p plan . Thi s contingenc y pla n allowe dfo r th e off-sit e disposa l o f

contaminate dsoi l withou t prio r treatment , an dwa s invoke db y EP A o n Octobe r 10 . 1995 .I n Apri l 2002 , th e Settlin g Defendan t submitte dan evaluatio n o f th e technica

l practicability o f restorin g th e groundwate r at th e O'Conno r

Sit e t o drinkin g wate r

quality withi n areasonabl e perio do f time . Thi s evaluatio n conclude dthat becaus e o f

th e geological an dhydrologica l condition s at

th e Site , ther e were n o technologie s whic h coul daccomplis h thi s objectiv e (th e thir dRA O i n th e 198 9 ROD) . Th e evaluatio n wa s resubmitte di n Jun e 200 2 followin g EP A an d Main e DE P comments . EPA , wit h concurrenc e fro mMain e DEP , approve dth e Jun e 200 2 evaluation . Wit h recognitio n tha t

i t wa s technicall y impracticabl e t o restor e th e groundwate r withi n alimite d are ao f th e Sit e t o drinkin g wate r standards , EP A issue daPropose dPla n i n lat e Jun e 2002 . I n thi s Plan , EP A propose dt o change dth e remed y fo r th e Site . Followin g aperio do f publi c comment , an dafte r

receivin g categorica l concurrenc e fro mMain e DEP , EP A issue daRO D Amendment . Th e September

200 2 RO D Amendmen t

selecte daremed y consistin g o f institutiona l controls , activ e an dpassiv e oi l recovery , long-ter mmonitorin g o f groundwater , an dfive-yea r reviews . Thi s RO D Amendmen t

recognize dth e technica l impracticabilit y o f achievin g th e thir dRA O throug h activ e pump-and-trea t fo r alimite dare ao f

th e Sit e withi n areasonabl e tim e frame . I t establishe datechnica l impracticabilit y zon e fo r thi s portio n o f

th e Sit e wher e stat e an dfedera l drinkin g wate r

standard s ar e waived . A compariso n o f

th e origina l 198 9 remed y fo r groundwate r

an dth e modifie dremed y i s provide d i n Tabl e 1 . D . Remedia l Design/Remedia l Actio n fo r Contaminate dOn-Sit e Surfac e Water s Th e 199 1 Statemen t

o f Wor k require da s par t

o f th e sourc e contro l componen t th e followin g action s fo r

on-sit e surfac e water : drainin g an doff-sit e transpor t o f surfac e waters , off-sit e treatmen t o f surfac e waters : an dsurfac e wate r drainag e modifications . Surfac e wate r

fro mth e Uppe r

Lagoo n an dstor mwate r

wer e dispose doffsit e a t

specia l wast e an d TSC A facilities . Sample s collecte dfro mth e Lowe r Lagoo n wer e belo w detectio n limits , an d followin g revie w an dcommen t b y Main e DEP . EP A approve dth e on-sit e discharg e o f th e surfac e wate r

fro mth e Lowe r

Lagoon . A t

th e en do f

sourc e contro l activities , th e sit e drainag e pattern s wer e restore dt o pro-sourc e contro l conditions . N o furthe r

activitie s ar e require dfo r on-sit e surfac e water . A mor e complet e descriptio n o f th e sourc e contro l activitie s ca n b e foun di n th e Septembe r 199 8 Sourc e Contro l Remedia l Actio n (SCRA ) report . L : . Remedia l Design/Remedia l Actio n fo r Contaminate dOn-Sit e Soi l an dSediment s T o mee t th e firs t tw o RAOs . reductio n o f publi c healt h an denvironmenta l risk s fro mdirec tcontac t

with contaminate dsoils , an dreductio n o f publi c healt

h risk s fro minhalation s o f PC B vapors , th e 1994 RSO W (revise dt o coincid e wit h th e change s describe di n th e ESD ) require da s par t o f th e sourc e contro l componen t th e followin g action s fo r on-sit e soil s an dsediments : decontamination/demolitio n o f th e on-site barn ; site preparatio n activities ; excavatio n an d consolidatio n o f

soi l an dsedimen t

wit h PC B concentration s betwee n 1 an d1 0 pp mint o th e designate darea ; off-sit e disposal o f soi l an dsedimen t

wit h greate r

tha n 1 0 pp mPCB s t o permitte dRCRA/TSC A facilities ; replacemen t o f th e to p twelv e inche s o f

th e designate dare a wit h clea n fil l fro moff-sit e sources ; replacemen t o f th e excavate darea s outsid e th e designate d are awit h clean fil l fro moff-sit e sources ; sit e restoration ; an destablishmen t o f compensator y wetlands . Th e firs t tw o RAO s wer e achieve dwit h th e completio n o f th e sourc e contro l remedia l actio n i n 1997 . Th e soi l clean-u p bega n i n 199 6 wit h th e cleaning , demolition , an doff-sit e disposa l o f th e barn situate dalon g Rout e 17 , an dothe r sit e preparatio n activities . Th e soi l cleanu p wa s complete di n 1997 . Thes e activitie s include dth e excavatio n an doff-sit e disposa l o f nearl y 20,00 0 ton s o f

soil . A n additiona l 3000 t o 400 0 ton s o f soil s wit h PCB s o r

PAH s concentration s betwee n 1 an d1 0 pp mwer e place dwithi n th e designate dare aonsite . Thi s are awa s the n covere d wit h aminimu mo f

on e foo t o f clea n fil l brough t

i n fro moffsite . Th e entir e Site wa s the n graded . Th e on-sit e wetland s wer e restored . A n additiona l 0. 4 acr e o f wetland s wa s create di n th e forme r lagoon s a s replacemen t

fo r wetland s los t

a s aresul t

o f th e clean-u p activities . Laborator

y test s o f sample s collecte dfro mth e botto man dperimete r o f th e excavatio n demonstrate dtha t

th e excavatio n ha dremove dth e contaminate dsoi l t o th e performanc e standard s se t

i n th e 199 4 ESD . Wit h th e completio n o f

th e sourc e contro l activitie s an dth e approva l o f th e SCR A report , th e Settlin g Defendan t

initiate doperatio n an dmaintenanc e activitie s pe r Sectio n K . o f

th e 199 4 RSOW . Operatio n an dMaintenanc e activitie s specifi c t o sourc e contro l includ e monitorin g o f wetlan drestoratio n an dmaintenanc e o f th e soi l cove r

i n th e designate darea . Th e restore d wetland s hav e bee n monitore dannuall y fro m199 8 throug h 2002 . Th e nex t an dfina l schedule d wetlan dmonitorin g activit y shal l b e performe di n 2007 . I n additio n t o periodi c monitorin g o f th e soi l cove r

fo r crosiona l features , th e Settlin g Defendan t shal l als o demonstrat e th e integrit y o l th e soi l cove r throug h sampling . A t

fiv e yea r interval s coinciden t

wit h eac h five-yea r

review , th e Settlin g Defendan t shal l collec t

composit e sample s fro mte n location s randoml y selecte dfro mth e SCR A gri dnodes . Thes e sample s shal l b e collecte dfro mfou r

t o eigh t inche s belo w th e surfac e an danalyze dfo r PCBs . Th e 199 4 ES D establishe dtha t aportio n o f

th e Sit e woul db e use dt o consolidat e soi l an d sedimen t containin g level s betwee n on e an dte n pp mo f PCB s an do r

cPA l Is . A s conceptuall \ presente di n th e ESD , th e designate dare awa s thre e t o fou r acre s bounde do n fiv e side s wit h rounde dturnin g points . A s th e actua l excavatio n fo r th e sourc e contro l remedia l actio n evolved . th e boundar y o f

th e designate dare abecam e a25-side dpolygon . Thi s create dadifficul t situatio n

### fo r

anyon e inspectin g th e Sit e t o kno w wher e th e boundar y was . Th e Settlin g Defendan t shal l surve y th e designate darea , th e boundarie s shal l b e simplifie dt o th e 10-side dshap e show n i n Figur e 5 o f

th e 200 2 RO D Amendment , an dpermanen t marker s shal l b e place dat th e turnin g points . A mor e complet e descriptio n o f th e sourc e contro l activitie s ca n b e foun di n th e Septembe r 199 8 SCR A report . F . Remedia l Design/Remedia l Actio n fo r Contaminate dGroundwate r T o mee t th e thir dRAO , reductio n o f futur e healt h risk s fro mingestio n o f contaminate d groundwate r

foun do n th e Site , th e 199 1 SO W require dth e establishmen t o f temporar y institutiona l controls , installatio n o f groundwate r

extractio n well s an dadditional monitorin g wells , an dinstallatio n an doperatio n o f agroundwate r

treatmen t an ddischarg e system . Th e groundwate r

remed y selecte di n th e 198 9 RO D include dpumpin g wells , atreatmen t system , an danetwor k

o f monitorin g well s t o trac k contaminatio n levels . Th e inten t wa s t o pum p an d the n trea t groundwate r

whic h containe ddissolve dPCB s an dVOC s an dthereb y restor e th e qualit y o f th e groundwater . A s par t o f desig n activities , apumpin g tes t wa s conducte di n TW A I I i n 199 2 t o determin e th e numbe r o f well s an dcomponent s o f

th e pum p an dtrea t

system . Subsequen t

t o thi s test , separat e phas e oi l wa s detecte di n th e bedrock . Consequently , th e focu s turne dt o remova l o f oi l fro mth e subsurfac e rathe r

tha n pumpin g an dtreatin g groundwater . A vacuum-enhance dsyste mt o recove r separat e phas e oi l wa s operate di n 199 6 - 1997 , prio r t o th e sourc e contro l excavatio n an dremova l activities . Followin g th e sourc e contro l activities , oi l wa s recovere db y placin g absorben t material s i n th e extractio n an dmonitorin g wells . Fro mAugus t t o Octobe r

2001 , th e vacuum-enhance dsyste mwa s agai n operate da s par t o f th e T I evaluation . Approximatel y twent y gallon s ofoi l wer e recovered . Th e 198 9 RO D wa s amende di n Septembe r 200 2 followin g a n evaluatio n o f th e technica l practicabilit y o f

restorin g th e groundwate r withi n areasonabl e tim e period . Th e RO D Amendmen t

change dth e remed y fo r

groundwate r

i n orde r t o mee t th e Remedia l Actio n Objective . Rathe r

tha n achievin g thi s objectiv e throug h pump-and-treat . th e 200 2 RO D Amendmen t

include ddesignatio n o f

a'1 1 zone , activ e an dpassi\ c oi l recover) . insiiUiliviia l controls , long-ter mmonitoring , an dfiv e yea r reviews . T l Zon e Followin g th e evaluatio n o f th e technica l practicabilit y o f restorin g groundwate r

t o drinkin g wate r standards , aT I zon e wa s establishe dfo r alimite dportio n o f

th e Sit e (se e figur e 3 o f

th e RO D Amendmen t

fo r th e T I zone) . Groundwate r beyon dth e T I zon e shal l mee t th e performanc e standard s liste dabove .Activ e an dPassiv e Oi l Recover y Th e Settlin g Defendan t

shal l operate , o n an annua l basis , avacuum-enhance drecovery syste m (VER ) t o remov e oi l an dassociate dPCB s whic h ha s accumulate dabov e th e wate r table . Thi s syste mshal l b e operate do n a n annua l basi s i n lat e summer - earl y fal l unti l i t i s determine dt o b e n o longe r effective . Criteri at o b e use dt o mak e thi s determinatio n includ e th e following : appl y th e VE Rt o fou r

well s (101 , 202B , 301B , an d302B ) i n th e TW A I I are aa t leas t onc e ever y year

fo r th e nex t fiv e year s (throug h 2007) ; afte r applicatio n o f

th e VE Rt o awell , recovery o f oi l wil l b e observe dove r aperio do f u p t o on e week . I f

a"significan t

" amoun t

o f oi l i s recovere dfro mth e well , th e VE Rwil l b e reapplie dt o th e well . A "significant " amoun t o f oi l i s define da s a n increas e i n th e amoun t o f oi l recovere drelativ e t o th e amoun t o f oi l recovere dthroug h passiv e means . Therefore , i f

th e VE Ri s effectivel y increasin g th e amoun t o f oi l bein g recovere dfro ma well , i t wil l continu e o n tha t

well ; th e operatio n o f

th e VE Rshal l continu e fo r aperio do f

u p t o tw o month s i f

significan t amount s o f

oi l ar e recovered . Afte r

thi s tim e weathe r

constraint s an drisin g groundwate r elevation s ar e expecte dt o limi t th e effectivenes s o f

th e VER ; an d th e necessit y an dcondition s fo r continuatio n o f

th e VE Rshal l b e addresse ddurin g th e nex t fiv e 5-yea r

review , schedule dfo r

Septembe r

2007 , an deac h subsequen t 5-yea r revie w period . Followin g operatio n o f

th e VER , absorben t

material s shal l b e place di n monitorin g well s t o absor b an y remainin g residua l oil . Th e us e o f absorben t

material s shal l continu e unti l a s lon g a s i t i s practical , i.e . a s lon g a s oi l i s visibl y detectable . Betwee n activ e operatio n o f th e VER . th e \\cll s shal l b e monitore dfo r oi l accumulatio n o n amonthl y basis . I t i s anticipate dtha t

thi s frequenc y wil l b e reduce dt o quarterl y i n th e future . Al l recovere doi l an duse dabsorben t materia l shal l b e dispose do f a t alicense dTS D facility . Institutiona l Control s Th e Settlin g Defendan t

shal l implemen t

th e component s o f

th e restrictiv e covenan t

recorde di n th e Kennebe c Count y Registr y o f Deed s o n Septembe r

13 . 2002 . a s discusse dfurthe r i n Sectio n H o f thi s SOW . 1.one-Ter mMonitorin g Th e Settlin g Defendan t

shal l continu e th e groundwate r monitorin g progra mt o trac k dissolve d PC B an dVOCs . Thi s long-ter mmonitorin g progra mshal l b e conducte dtwic e yearly , i n sprin g an dfall . Th e monitorin g progra mwil l als o requir e trackin g th e attenuatio n o f dissolve dcontaminan t level s beyon dth e are awher e th e oi l i s presen t i n th e groundwater . Thi s monitorin g dat ashal l b e use dt o verif y tha t th e dissolve dcontaminan t concentration s ar e decreasing . Finally , thi s componen t

o f th e remedy shal l includ e contingencie s shoul dth e groundwate r monitorin g indicat e th e contaminatio n i s movin g beyon dit s curren t limits . Contingencie s may includ e increase dsamplin g frequency , implementatio n o f additiona l samplin g locations , includin g an y residential well s installe do n adjacen t properties , reevaluatio n o f th e conceptual model , an d increase doperatio n o f

th e VER . Thi s progra mshal l b e maintaine dunti l i t ha s bee n determine db y EPA , afte r opportunit y fo r revie w an dcommen t

b y Main e DEP , tha t

th e groundwate r

i n th e overburde n soil s an di n th e bedroc k hav e achieve dth e performanc e standard s define dabove . Th e scop e o f

th e long-ter mmonitorin g progra mwil l b e reviewe dperiodicall y b y th e Settlin g Defendan t

an dEPA , wit h opportunit y fo r revie w an dcommen t

b y Main e DEP . Review s wil l occu r a t leas t yearly , followin g receip t o f th e samplin g report

followin g th e fal l samplin g event . I n addition , th e scop e o f

th e long-termmonitorin g programshal l als o b e reviewe di n connectio n wit h th e five-yea r

reviews . Upo n thes e review s o r a t an y othe r tim e EPA , afte r

opportunit y fo r revie w an dcommen t

b y Main e DEP , ma y requir e modificatio n t o th e monitorin g progra mbein g conducte db y th e Settlin g Defendant . Suc h modification s woul db e effectiv e thirt y (30 ) day s afte r writte n notic e b y EPA , unles s EP A specifie s alonge r perio do f time . Th e Settlin g Defendan t ma y reques t

modification s o f

th e monitorin g program , includin g reductio n i n samplin g frequency . I f

warranted , EPA , afte r

opportunit y fo r

revie w an dcommen t

b y Main e DEP , shal l gran t suc h modification s base do n th e availabl e dat aan devaluatio n o f th e data . Th e result s o f

th e groundwate r

samplin g performe di n accordanc e wit h th e monitorin g progra m shal l b e submitte dt o EP A an dMain e DE P withi n forty-fiv e day s o f receip t o f th e dat afro mth e laboratory . Five-Yea r

Review s A s lon g a s contaminatio n remain s whic h prevent s unrestricte dus e o f th e Site , five-yea r

review s shal l b e performe dt o evaluat e th e effectivenes s o f th e implemente dcleanu p plan . A s par t o f eac h five-yea r

review . EP A shal l revie w th e sit e condition s t o ensur e tha t th e remed y continue s t o provid e protectio n o l huma n healt h an dth e environment . A s note dabove , samplin g o f th e soi l cove r

fo r th e Designate dAre awil l b e don e coinciden t wit h th e five-yea r

review s t o demonstrat e th e integrit y o f th e soi l cover . I n addition , coinciden t wit h th e five-yea r

reviews , th e PC B analysi s performe dfo r th e groundwate r

outsid e th e T I zon e shal l us e method s capabl e o f

lowe r detectio n limit s i n orde r

t o compar e th e concentratio n level s wit h th e Main e ME G o f

0.0 5 uG/L. .G . Remedia l Design/Remedial Actio n fo r Rigg s Broo k T o meet th e fourt h an d fift

h RAO s o f

th e 198 9 ROD , reductio n o f publi c healt

h risk s fro m ingestio n o f

PCB-contaminate dfis h fro mRigg s Brook , an dreductio n o f risk s t o aquati c an d terrestrial wildlif

e fro mexposur

e to contaminate dsediments , th e 199 1 Statement o f Work identifie dfou r

activitie s fo r

Rigg s Broo k

a s part o f th e managemen t

o f migratio n control component . The y were th e establishmen t an dimplementatio n o f

ate n yea

r sedimen t

samplin g an danalysi s program ; a t leas t on e fis h tissu e samplin g even t afte r fiv e year s o f

sedimen t sampling , publi c relation s procedure s t o infor mth e communit y abou t th e potentia l risk s associate dwit h Rigg s Brook ; an dfive-yea r reviews . Performanc e standard s fo r Rigg s Broo k

sedimen t

an dbiot awer e se t

i n th e 198 9 RO D a t

1 pp m PCB s an d2 pp mPCBs , respectively . However , i t wa s agree da t

tha t tim e tha t

th e negativ e short

ter mimpact s t o th e wetland s ecolog y outweighe dth e remova l o f sediment s t o tha t

level . A trigge r leve l o f 5 pp mPCB s fo r

furthe r actio n wa s therefor e establishe dA s state di n th e 199 1 SOW , "i f th e PC B level s withi n Rigg s Broo k ar e foun dt o excee d5 pp mi n th e sediment s and/o r 2 pp mi n th e fis h tissu e samples , th e Settlin g Defendan t shal l desig n an dimplemen t amor e rigorou s samplin g effor t withi n Rigg s Broo k

t o determin e th e nee dand/o r exten t o f furthe r Remedia l Actio n withi n Rigg s Brook , i f any. " Thi s occurre di n 199 7 whe n soi l an dsedimen t abov e 5 pp mPCB s wer e remove dsimultaneousl y wit h th e ongoin g sourc e contro l remedia l action , an dagai n i n 199 9 an d200 0 whe n additiona l sample s wer e collected . Th e Settlin g Defendan t bega n sedimen t

samplin g i n 1996 , an dlia s conducte dtu o fis h tissu e samplin g event s (199 7 an d2000) . Th e las t tw o sedimen t

samplin g event s hav e ha donl y on e exceedanc e o f

th e 5 pp mtrigge r

ou t o f thirty-si x locations ; th e majorit y o f result s hav e bee n belo w detectio n limits . Th e fis h tissu e analysi s demonstrate dtha t concentration s o f

PCB s detecte ddi dno t

excee dth e RO D targe t leve l o f 2 ppm , an di n fac t

hav e al l bee n belo w 1 ppm . Th e Settlin g Defendan t

shal l continu e th e annua l sedimen t samplin g throug h 2005 . Furthe r fis h samplin g ma y b e necessar y a s par t o f th e furthe r

Remedia l Actio n specifie dalxn c shoul dth e PC B concentration s excee d5 ppm . 11 . Sit e Acces s an dInstitutiona l Control s A Restrictiv e Covenan t

ha s bee n signe db y th e Settlin g Defendan t an dMain e DE P tha t

prohibit s us e o f th e groundwate r

beneat h th e Site . Publi c wate r i s availabl e o n Rout e 1 7 t o th e sout h an d t o residentia l propertie s o n Con y Roa dt o th e west . Th e neares t know n residentia l \\el l i s approximate! ) ahal f

mil e t o th e east , situate do n ahil l abou t tu o hundre dfee t

abov e th e Rigg s Broo k discharg e area . Thi s wel l intercept s flo\ \mo \in g \\es t towar dRigg s Brook . 1 heretore . ther e i s n o curren t

drinkin g wate r

exposur e t o th e groundwate r whic h flow s beneat h th e Site . Thi s Restrictiv e Covenan t shal l remai n i n plac e unti l terminate db y Main e DHP . Shoul d1 PA .however , fin dthat thi s covenan t

i s n o longer

protective , effective , o r

i t interfere s with th e performanc e o f

th e remedy , additiona l institutiona l control s shal l b e place do n th e property . I . Remedia l Desig n Th e 199 1 SO W require dth e Settlin g Defendan t t o perfor mpre-desig n activitie s fo r bot h sourc e contro l an dmanagemen t

o f migration . Thes e include dapilot-scal e treatabilit y stud y o f th e solven t extractio n proces s fo r

th e sourc e contro l componen t an dapilot-scal e aquife r

tes t an d treatabilit y stud y fo r

th e managemen t

o f migratio n component . Thes e .wer e complete dan dth e result s submitte dt o EP A i n Novembe r 1993 . Th e 199 4 RSO W require dth e Settlin g Defendan t t o submi t

aserie s o f

wor k plan s an ddesig n document s (30% , 60% , 95% , an d100 % designs) . Th e wor k plan s an ddesig n documents , wit h th e exceptio n o f

th e O& M plan , hav e bee n approve db y EPA , afte r opportunit y fo r

revie w an d commen t b y Main e DEP . Ther e ar e n o furthe r

remedia l desig n requirements . J . Remedia l Actio n Th e 199 4 RSO W establishe daschedul e fo r implementin g remedia l actio n fo r sourc e contro l an d managemen t

o f migratio n component s a s wel l a s documentatio n requirements . Th e sourc e contro l component s wer e complete di n 199 7 an dfina l documentatio n fo r sourc e contro l wa s submitte di n Septembe r

1998 . Wit h th e determinatio n o f technica l impracticabilit y fo r alimite d portio n o f

th e Site , th e managemen t o f migratio n componen t

ha s bee n modifie da s note dabove . K . Operatio n an dMaintenanc e Th e Settlin g Defendan t

submitte da n Operatio n an dMaintenanc e Pla n a s par t o f th e SC'R A an d the n revise di t

fo r revie w an dapprova l i n 2002 . Upo n approva l b \F.PA . afte r opportunit y fo r revie w an dcommen t

b y Main e DEP . th e Settlin g Defendan t shal l implemen t

th e O& M plan .

### Tabl e 1 : Compariso n betwee n 1989 RO D an d200 2 RO D Amendmen t

1989 RO D - Groundwate r component s #1 : temporar y institutiona l controls . Thi s woul dpreven t

exposur e t o sit e groundwate r whil e remediatio n wa s underway . #2 : pump-and-trea t

system . Th e appropriat e sizin g o f th e system , includin g th e numbe r o f extractio n wells , pumpin g rate , treatmen t component s suc h a s granula r activate dcarbon , san dfilters , ai r

stripper , an dnumbe r

o f recharg e well s wa s t o b e determine ddurin g th e remedia l desig n phase . #3 : anetwor k

o f monitorin g wells . Th e well s use di n th e R I woul db e assesse dan daugmente d wit h additiona l well s i n bot h overburde n soi l an dbedrock . #4 : Rigg s Broo k

sedimen t

an dbiot amonitoring . Broo k sediment s wer e t o b e monitore dyearl y fo r te n year s t o asses s PC B concentrations . Biot asamplin g wa s t o occu r fiv e year s afte r initiatio n o f

th e monitoring . #5 : five-yea r

reviews . Th e progres s towar d restoratio n o f

th e sit e groundwate r

an dth e targe t clea n u p goa l fo r

th e sedimen t

uer e t o h e assesse dduru meac h five-yea r revieu . 

### 200 2 RO D Amendmen t # 1 permanen t

institutiona l controls . Wit h th e 199 4 BSD , CM P an dMain e DE P signe da restrictiv e covenan t

whic h prevente dcertai n activitie s a t

th e Sit e withou t

writte n approva l o f Main e DEP . #2 : annua l applicatio n o f th e VE Rsystem . Th e VE Rha s bee n operate dthre e time s post-ROD , recoverin g PCB-lade n oi l fro mth e overburde n an dbedrock . Th e VE Rwil l b e applie dannuall y i n TW A I I are awell s t o recove r a s muc h oi l a s i s practical . # 3 monthl y monitorin g o f oi l level s i n TW A I I well s an dremova l usin g absorben t materials . Betwee n th e annua l operation s o f th e VER . th e TW A I I wil l b e monitore dfo r separat e phas e oil . Detecte doi l wil l b e remove dusin g absorben t material . I t

i s expecte dtha t monitorin g frequenc y wil l decreas e a s th e amoun t o f oi l drainin g int o th e well s decreases . #4:long-ter mmonitoring . I t wil l b e performe d t o trac k contaminan t

level s i n th e T l zon e an d outsid e it. ' ??5 : Rigu. s Broo k

scdmien ! am i bioi a I t wil l continu e a s establishe di n 199 6 #6 : five-yea r

reviews . Review s wil l b e conducte dt o ensur e tha t

th e sit e remed y remain s protective .

1 0

### APPENDI X I I T O AMENDMEN T T O O'CONNO RCONSEN T DECRE E REMEDIA

L DESIGN/REMEDIA

L ACTIO N STATEMEN T O F WOR K ATTACHMEN T A PROJEC T OPERATIO N PLA N Th e Settlin g Defendan t

submitte daProjec t

Operation s Pla n i n accordanc e wit h th e 199 4 revise d SOW . Th e Projec t

Operatio n Pla n include dfou r site-specifi c plans : Sit e Managemen t

Pla n Samplin g an dAnalysi s Pla n Healt h an dSafet y Pla n Communit y Relation s Suppor t Plan . EPA , afte r

revie w an dcommen t

b y Main e DEP , approve dth e POP . Th e Samplin g an dAnalysi s Pla n consiste do f tw o parts : aQualit y Assuranc e Projec t Plan , an da Fiel dSamplin g Plan . A s arequiremen t o f thi s Statemen t

o f Work , th e Settlin g Defendan t shal l submi t a n updat e o f

th e QAPP . Th e revise dQAP P shal l b e i n accordanc e wit h EP A guidanc e documen t QAMS-OO5/8 0 an dappropriat e EP A handbooks , manuals , an dguidelines , includin g Regio n I' s Octobe r

199 9 Compendiu mo f

Qualit y Assuranc e Projec t Pla n Requirement s an d Guidance .

1 1