## FIV E YEA RREVIE W

TOW N GARAGE/RADI O BEACO N SUPERFUN D SITE LONDONDERRY , NE W HAMPSHIR E CERCLI S ID . #NHD98106386 0

Prepare d by : U.S . Environmenta l Protectio n Agenc y

Regio n 1 Boston , Massachusett s Marc h 199 9I . Introductio n

Purpose EP A Regio n I performe dafive-yea r revie w o f

th e Tow n Garage/Radi o Beaco n Sit e pursuan t

to CERCLA sectio n 121(c) , NC P sectio n 300.400(f)(4)(ii) , an d OSWERDirective s 9355.7-0 2 (Ma y 23 , 1991) , an d 9355.7-02 A (Jul y 26 , 1994) . I t i s apolic y revie w becaus e unrestricte dus e o f th e propert y wil l b e allowe donc e groundwate r remedia l actio n objective s ar e achieved . Th e purpos e o f

thi s five-yea

r revie w i s t o ensure that

th e remedia l actio n remain s protectiv e o f public health an dth e environmen t an di s functionin g a s designed . Thi s documen t wil l becom e apart

o f th e Sit e file . Thi s repor t

i s aTyp e I leve l revie w whic h i s appropriat e at site s wher e circumstance s whic h may compromis e protectivenes s ar e no t present . Site Characteristics Th e Tow n Garage/Radi o Beaco n Superfun dSit e i s locate dnort

h o f Pillsbur y Roa dnea

r th e intersectio n o f

Pillsbury an dHig h Rang e Road s i n Londonderry , Ne w Hampshire . Th e Site stud y are aencompasse daresidential developmen t o f 2 3 home s (Holto n Circle) , th e Londonderr y town garag e are alocate do n Hig h Rang e Road , an daformerl y undevelope dhillslop e an dwetlan dare a betwee n th e tow n garag e an dHolto n Circl e (se e attache dfigure) . A residentia l subdivisio n o f 1 2 home s (Saddlebac k

Road ) wa s recentl y constructe do n th e hillslop e area . Al l home s i n th e Saddlebac k Roa dsubdivisio n ar e attache dt o apubli c wate r supply . Nin e home s i n th e Holto n Circl e subdivisio n remai n o n privat e well s sinc e the y hav e alon g history o f remainin g unaffecte db y th e groundwate r contamination . Th e Sit e wa s discovere di n 198 4 followin g areques t t o th e Stat e b y resident s o f th e Holto n Circl e subdivisio n t o sampl e thei r bedroc k wells . Samplin g result s fro mth e Ne w Hampshire Departmen t

o f Environmental Service s (NHDES ) reveale dth e presenc e o f volatil e organi c compound s (VOCs ) i n severa l o f th e residentia

l drinkin g wate r well s an dth e nearb y tow n garag e well . Th e majo r contaminant s detecte dinclud e 1, 1 dichloroethen e (1,1-DCE) ; 1, 1 dichloroethan e (1,1-DCA) ; an d 1,1, 1 trichloroethan e (1,1,1-TCA ) a t level s abov e federal an d stat e primar y drinkin g wate r

standards . Four

no n site-related metals ; barium , beryllium , chromiu man dantimon y wer e als o discovere da t concentration s i n exces s o f drinkin g wate r

standards . Th e Sit e wa s adde dt o th e Nationa l Prioritie s Lis t (NPL ) i n Marc h 

### 1992 . A Recordo f

Decisio n (ROD ) wa s issue do n Septembe r 30 , 199 2 an d calle dfo r

natura l attenuatio n o f

VO C contaminant s i n groundwate r with ongoin g monitorin g an dth e establishmen t o f institutiona

l control s t o ensure that

groundwate r

woul dno t

b e use da s apotabl e sourc e unti l federa l an d state drinkin g wate r standard s ar e achieved . Wit h regar dt o metals , th e RO D conclude dthat

elevate dconcentration s wer e probabl y du e t o samplin g artifact s an d no t representativ e o f

actua l conditions . Re-samplin g o f groundwate r

b y an improve dmetho d(low

flow ) wa s require dto verif y actua l conditions . Groundwater monitorin g wa s performe db y th e N H DE S unti l aUnilatera l Administrativ e Orde r wa s issue dt o th e Tow n o f Londonderry o nSeptembe r 30 , 1996 . Th e Tow n wa s th e onl y potentially-responsibl e part y identifie dfo r th e Site . Th e Tow n implemente drequire dinstitutiona l control s an dhire daconsultan t t o perfor m continue dgroundwate r

monitoring . II . Remedia l Actio n Objective s EPA' s primary responsibility at thi s Site , an dal l Superfun dsites , i s t o undertak e remedia l action s that ar e protectiv e o f

huma n healt

h an dth e environment . I n addition , Sectio n 12 1 o f CERCLA establishe s severa

l othe r statutor y requirement s an dpreferences , includin g arequiremen t tha t EPA' s remedial action , whe n complete , mus t compl y wit

h al l federa l an dmor e stringent stat e environmental standards , requirements , criteri ao r limitations . Respons e alternative s wer e develope dt o b e consisten t wit h thes e requirements . Remedia l actio n objective s were develope dto ai d i n th e screening o f respons e alternative s an d wer e develope dt o mitigate existin g an d futur e potentia l threat s t o publi c healt h an d th e environment . Th e remedia l actio n objectives , a s specifie di n th e Recor do f Decisio n (ROD ) are : 1 . Preven t

ingestio n o f

wate r whic h contain s compound s i n concentration s that excee dfederal an dstate enforceabl e drinkin g wate r standards ; 2 . Preven t

ingestio n o f

wate r containin g compound s whic h hav e n o enforceabl e federa l o r state drinkin g wate r

standard s bu t

whic h pos e an unacceptabl e healt h risk ; an d 3 . Restore groundwate r quality t o federa l an d stat e drinkin g wate r standards . Th e RO D estimate dthat

natura l attenuatio n woul drequir e seven t o twenty-fiv e year s t o reduc e contaminant s to belo w drinkin g wate r standards . Sinc e th e RO D wa s approved , si x year s o f annual groundwate r

monitorin g hav e bee n performe dat nin e overburde n an deight bedroc k wel l locations . I n general , contaminan t

level s hav e droppe dsubstantiall y i n th e overburde n aquife r an dhav e decrease dslightly o r

remaine dconstant

i n th e bedroc k

aquife r (wit h on e exception) , sinc e initia l post-RO D samplin g i n 1994 . Th e tabl e belo w demonstrate s th e chang e i n contaminant level s a t ke y monitorin g wells .

Page-2

-MW Locatio n

Cleanu p Level s MW-2 S MW-2D-6 * MW-3 D MW-4D-3 * MW-5 S MW-6D-4 * MW-8 D Dat e

Jun e 

### '9 4 No v *9 8 1, 1 DC A

pp b 8 1 pp b 7 4 100 1 1 7. 6 1 4 5. 2 4 8 3 3 11 0 

### 7 7 BD L 1 6 

### 5 1, 1 DC E

pp b 7 pp b 

### 1 8 3 7 5. 8 6. 5 2 1 BD L 2 8 8 5 8 4 1 5 7 3 

### 1,1, 1 TC A

pp b 20 0 pp b 79 0 30 0 BD L 4 1 19 0 BD L BD L 8 1 15 0 BD L 6 2 7 BD L BD L Tota l VOC s

pp b 

### 88 2 43 7 

### 16. 8 55. 1 22 5 5. 2 7 6 12 2 31 8 1 1 1 4 3 2 2 3 8

* Multi-level bedroc k

well s (mos t

contaminate dzon e wa s selected) S - overburde n wel l D - bedroc k

wel l BD L - belo w detectio n limi t Cleanu p level s - federa l MCL s o r stat e AGQS s Shade dcolumn s ar e mos t

recen t Novembe r

98 ' dat a Bol ddat aexcee dgroundwate r cleanu p standard s A s show n i n th e tabl e above , onl y on e overburde n wel l (MW-2S ) stil l contain s 1, 1 DC E a t a leve l slightly i n exces s o f

it' s drinkin g wate r

standard . Thi s wel l ha s show n aclea r decreasin g trend . In th e bedrock , tw o well s (MW-2D an d MW-6D ) continu e to exhibit level s o f 1, 1 DC E an d1, 1 DC A i n exces s o f drinkin g wate r

standards . A s anticipated , th e rat e o f contaminan t reductio n i n th e bedroc k

i s muc h slower

than i n th e overburden . Th e sligh t increasin g tren di n DC E an d DC A level s a

t MW-6 D i s likely attributabl e t o th e continue ddegradatio n o f TCA . Barium , beryllium , chromiu man dantimon y wer e re-sample dusin g th e low-flo w samplin g method . Result s confirme dtha t actual concentration s di d no t exceed drinkin g water

standards . Thre e round s o f

subsequen t

monitorin g wer e performe dwhic h verifie dthi s result . Metal s wer e remove dfro mth e monitorin g program . Institutional

Controls A s aconditio n fo r

development , th e Tow n o f Londonderr y require dth e developer , Stonemar k Investments , Inc. , t o suppl y publi c wate r t o th e subdivision . Additionally , th e Tow n o f Londonderr y applie dfor , an dsubsequentl y received , aGroundwate r Management

Permi t fro m Pag e -3

-NHDE S i n Augus t 1997 . Issuanc e o f

thi s permi t

prevent s potabl e us e o f

well s withi n th e plum e area . Ther e ar e n o know n well s activ e withi n th e curren t plum e area . m . ARAR s Revie w Th e primary applicabl e o r relevant an dappropriat e requirement s (ARARs) , a s liste di n th e ROD , includ e th e chemical-specifi c group . Althoug h ther e ar e anumbe r o f locatio n an daction-specifi c ARAR s include di n th e ROD , thes e requirement s wer e easil y complie dwith sinc e th e remed y di dno t involv e an y physica l activities . Consequently , acloser revie w o f

locatio n an daction

specifi c ARAR s i s no t

warranted . Th e followin g chemical-specifi c ARAR s ar e include di n Appendi x C o f th e ROD :

• Federal Clean Wate r Ac t (CW A $304(a) ) Ambien t

Wate r Quality Criteri a

- state s that

ambien t water-quality criteri awil l b e attaine di n th e wetlan dsurfac e wate r • Federa l Saf

e Drinkin g Wate r

Ac t (4 0 CFR$ 141.1 1 - 141.16an d 141.50

- 141.51 )

- state s that

groundwate r

throughou t

th e plum e wil l attai n thes e standard s • Federa l Maximu mConcentratio n Limit s (4 0 CF R§ 264.94 )

- state s tha

t groundwate r

throughou t

th e plum e wil l attai n thes e standard s • Federa l Clea

n Ai r Ac t (4 0 CF RPar t

50 )

- state s that

th e selecte dclean-up actio n mus t no t excee dai r

standard s • Ne w Hampshir e Primary Drinkin g Wate r Standard s (Env-w s Part s 31 5 - 319 )

- state s tha

t groundwate r

throughou t

th e plum e wil l attai n thes e standard s Non e o f th e above-liste dstandard s ar e know n t o hav e bee n modified . Federa l an d state drinkin g wate r standard s hav e bee n attaine dfo r th e metal s barium , beryllium , chromiu man dantimon y an dprogres s towar dachievin g thes e standard s i s bein g mad e wit h respec t t o VOCs . Natura l attenuatio n progres s i s expecte dt o continu e an d shoul dreduc e VO C concentration s belo w require dstandard s i n on e t o ninetee n year s (base do n RO D estimates) . Complianc e wit h ambien t wate r qualit y criteri ai n th e wetlan dsurfac e wate r wil l b e verifie dfollowin g attainmen t o f drinkin g wate r

standard s i n th e overburde n an dbedroc k aquifers . Ai r

monitorin g i s routinel y performe ddurin g wel l samplin g a s par t o f worke r safety . Ai r

quality i s no t

an issu e a

t thi s site . IV . Summar y o f

Sit e Visi t O n Marc h 12 , 1999 , EPA an d NHDE S inspecte dth e Tow n Garage/Radi o Beaco n Sit e specificall y to determin e i f any change s had occurre dat , o r i n th e vicinit

y o f th e Sit e whic h woul dbrin g th e protectivenes s o f th e remed y int o question . Jame s DiLorenz o fro mEP A an d Pau l Lincol n fro mNHDE S participated . A s expected , significan t

residentia l developmen t

o f th e forme r

woode dhillslop e are ao f th e Sit e ha s occurred . A subdivision , know n a s Saddlebac k Road , ha s bee n complete dan dinclude s thirtee n (13 ) hom e site s o f approximatel y 3/

4 t o 2 acres . A s aconditio n fo r development , th e Page-4

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### Tow n o f

Londonderry require dth e developer , Stonemar k Investments , Inc. , t o suppl y publi c wate r t o th e subdivision . A conversatio n wit h th e Town' s Engineer , Gar y Tendler , confirme d that al l home s hav e bee n connecte dt o th e publi c wate r supply . A writte n agreemen t betwee n Stonemar k Investments , Inc . an dth e Tow n o f Londonderry , date dDecembe r 11 , 1996 , wa s reviewe dan dinclude s provision s fo r long-termacces s to , an dmaintenanc e of , monitorin g wells . Sit e observation s confirme dstatement s i n th e mos t recen t annua l monitorin g report

that wel l MW-2 S ha dbee n destroye dan dMW-2 D damaged , althoug h i t remain s functional . I t

appear s that th e destruction/damag e wa s aresul t o f ongoin g constructio n activitie s at th e Site . EP A sent alette r t o th e Tow n o f

Londonderr y date dMarc h 5 , 199 9 requestin g tha t wel l MW-2 S b e replace dan dMW-2 D b e repaired , a s necessary . Consisten t wit h th e term s o f

th e Unilatera l Administrativ e Order , th e Tow n i s require dt o respon dt o thi s reques t withi n thirty (30 ) days . I t i s expecte dtha t

th e Tow n wil l reques t

Stonemark

Investments , Inc . implemen t th e necessar

y repair s consisten t

with th e abov e agreement . Al l repair s mus t b e mad e n o late r

tha n th e next monitorin g period , Novembe r 1999 . Al l othe r

monitorin g well s ar e undamaged . V . Area s o f

Non-Complianc e Non e noted . VI . Recommendation s Base do n thi s five-yea

r revie w an dinformatio n containe di n th e mos t recent groundwate r monitorin g report , th e followin g action s ar e recommended : 1 . Th e curren t

annua l groundwate r

monitorin g progra mshoul dcontinue ; 2 . Monitorin g well s MW-2 S an dMW-2 D are critica l monitorin g location s an dshoul db e replace dand/o r

repaired , a s necessary , t o effectivel y monito r continue dprogres s toward s achievement

o f remedial objectives ; 3 . Th e Groundwate r

Managemen t

Permi t shoul db e maintaine dt o ensur e tha t potabl e well s ar e no t installe dwithi n th e plum e area ; an d 4 . Surfac e wate r

i n th e wetlan dare adirectl y downgradien t o f th e plum e shoul db e sample d onc e drinkin g wate r

standard s ar e achieve dt o ensure complianc e wit h CW A § 304(a) . VII . Statemen to f

Protectivenes s I certif y that th e remed y selecte dfo r

th e Tow n Garage/Radi o Beaco n Sit e remain s protectiv e o f huma n healt

h an dth e environment . Th e recommendation s liste di n Sectio n V I abov e are necessar y t o ensur e thi s protectivenes s findin g remain s valid . Pag e -5

-VHI . NextFive-Yea r Revie w

Th e planne ddat e fo r

thi s five-yea

r revie w wa s Septembe r

1997 . Managin g regional prioritie s delaye dexecutio n o f

thi s review . Consistent

wit h OSWERDirectiv e 9355.7-02A , th e nex t five-yea r revie w wil l b e conducte d b y Septembe r

2002 .

Patrici aL . Meaney , Directo r Dat e Offic e o f Site Remediatio n an dRestoration , Regio n 1

Page-6

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# Fig . 2 - Holto n Circle Sit e Ma p

Holto n Circl e

Forme r U.S
. Arm y Bldqs
.

Drawin g No t t o Scal e Wetland s Tow n Garage Propert y Fenc e Radi o Beaco n Are a Approximat e Bedroc k Contaminatio n Are a Approximat

e Overburde n Contaminatio n Are a Tow n Garage Are a Topsoi l Overburde

n Groundwator Bedroc k Groundwato r Environmenta

l Protectio

n Agenc y Propose

d Pla n • HoUonCbde Supafun d Sit e 7