I ROMS DocID 111059 DtTElCMJWATION RCHA Corrective Action Environmental Indicator (El) RCRIS code (GA750) Interim Final 2/5/99 FaCiI%:Naine: Mystic Station Facilify Address: 173 Alfind Steeet, Boston, MA Facility EPA ID #; MAD000842401 i, HasJR at^a)[jiefeievant/sipifi<?antinIcHmati» Bie groOTdtvater media, subject to RCRA Action (e.g., from Solid Waste Management Units (SWMU), Regulated Units (RIJ), and Areas of Goncem (AOG)), been considered in tins EI determination? X If yes -check here and continue with #2 below- Ifnor fe-evaluate existing dtt^ or if data^ trot available, skip to #S entet"E4'' (more ihforrtiation needed) status code. BACKGRQllHO Definirion of Enviimimental Indicators (for the RCRA Gorrective ActioaY I are measures being nsed j^ M progrdtntnatic activity measures («.g., rejportS received ^ approved, etc. jto track changes in die quaMty environment. The two K developed to-d^ of^e environment in relation to curieht human toqtost^s to eon^mation ahd the migj^oh of cbhtartin^ An EI for tron-human (ecological) receptors is intended to be developed fe iMnilion of "Migratiimoicy Under CoirtroP El tl" EI deaerminatiori ("YE" startus code) iiidicates that the ntigintlon of "contaminated"^undwater has st^ilized, arid tiiat monitoring will be conducted to conlirm that coritaminated-grenridwater reiriains within flie original "area of contaminated grouridw^eir" (for all groundwater "contamination" s^ject to RGRA corrective action ator from the identified faciliQf (i.e., site-wide)). Relationship of ll to Final Ifcemedlics While Etol r^edies retnaln the long-term oblective oftiie RGRA Gtoireettve Action program Ae EI toe t^arstei^ objectives vritich are currently being used as J^gratn injures for the Government Performance arid Results Acto^ 1993v GPRA); liie "Migration of Gontaminated Grburidwater Under Contiot" EI pertains 0>RY to the physical mi^ritibn#e;t foitijCT spreadjbfifoatammated gjoimd watoF'rind»!roritaiBMri^ nprisaipeoiris ligmA AcfoeVirig Ais Ei tibes not substitute for aclnevingo^ or final remetfy recprements and e3g««tations;assc»ciated wtAsourcesof contatni^ wherever pratcticaWe/ contaiAnated groundwater to be smteWe for ib designAed cnrrent and foture uses. Dnraflop / ApaBcabilitv of El IMerminatiorts EI Deteririiriatibns sfotus codes'Sho^d remmn in RGlUS national database ONEY as long as they true (i.e.> RCIUS status codes riiust be changed when the legyatoiy authorities beconto aware of coritiaiy irifoimation).
FaCiI%:Naine: Mystic Station Facilify Address: 173 AlfindSteeet, Boston, MA Facility EPA ID#; MAD000842401
i, HasJR at^a)[jiefeievant/sipifi<?antinIcHmati» Bie groOTdtvater media, subject toRCRA Action (e.g., from Solid Waste Management Units (SWMU), Regulated Units (RIJ), and Areas ofGoncem (AOG)), been considered in tins EI determination?
X If yes -check here and continue with #2 below-
Ifnor fe-evaluate existingdtt^ or
if data^ trot available, skipto #S entet"E4'' (more ihforrtiation needed) status code.
BACKGRQllHO
Definirion of Enviimimental Indicators(for the RCRA GorrectiveActioaY
I are measuresbeingnsed j^M progrdtntnatic activity measures («.g., rejportS received ^approved, etc.jto track changes in die quaMty environment. The two K developed to-d^ of^e environment in relation to curiehthuman toqtost^s to eon^mation ahd themigj^oh of cbhtartin^ An EIfortron-human (ecological) receptors is intended to be developed fe
iMnilion of "Migratiimoicy Under CoirtroP El
tl" EI deaerminatiori("YE" startuscode) iiidicates that the ntigintlon of "contaminated"^undwater hasst^ilized, arid tiiat monitoring will be conducted to conlirm that coritaminated-grenridwater reiriains within flie original"area of contaminated grouridw^eir"(for all groundwater "contamination" s^ject to RGRA corrective action ator from the identified faciliQf (i.e., site-wide)).
Relationship of llto Final Ifcemedlics
While Etol r^edies retnaln thelong-term oblective oftiie RGRA Gtoireettve Action programAe EI toe t^arstei^ objectives vritich are currently being used asJ^gratninjures for the Government Performance arid Results Acto^ 1993v GPRA); liie "Migration ofGontaminated Grburidwater Under Contiot" EI pertains 0>RY to the physical mi^ritibn#e;t foitijCT spreadjbfifoatammated gjoimd watoF'rind»!roritaiBMri^ nprisaipeoiris ligmA AcfoeVirig AisEi tibes notsubstitute for aclnevingo^ or final remetfy recprements and e3g««tations;assc»ciated wtAsourcesofcontatni^ wherever pratcticaWe/ contaiAnatedgroundwater to be smteWe for ibdesignAed cnrrent and foture uses.
Dnraflop /ApaBcabilitv of El IMerminatiorts
EI Deteririiriatibnssfotus codes'Sho^d remmn in RGlUS national database ONEY as longas they true (i.e.> RCIUS status codes riiust be changed when thelegyatoiy authorities beconto awareof coritiaiy irifoimation).
2. Is ®rijHii#watcr kjK^ susp^d to fee approprial^y prote "levels" (i.e., applicable promulgated standards, as well as other appropriatestandards, guidelines, guidance; or cnteria)firomr^eases spyect toSXMCoiipc^
X If yes- (xininue after identifying key contammaiSiCitihgappropriate "levelsi"^^^ . referencing supportingddeoMteite^ v
If BO - skip to #8 and enter"VE" status code, altociting appropriate"levels," and tefertotartg sdPftorting dOOpaien^ "cofltamMated."
If unknown - skipto #8-and eater"IN" statuscode.
Rationale and Reference^); See atteched aartativfe
3. Has'the ^ration of contaiiiiraateidgtowndWfteij^t^feedf^^^ expected to remain within "existing area of contaminated ^oundwater"^as defin^ by tbe monitoring
: -• .•• • :X., •: teyesrictHlhnue^a|fteI;IM«seHting orreferee ssmpjfeg/m^ur^nenVffiigratijm bapieid^) groundvt^i^ isiexpectedto remain withia to^ dimensions of the "existing area ofgroundwater contaminalipn"^).
^ "existingaiea of contaminated gtpundwatef"isah area{im& horizontal and vert^^ dmiensibns) thathas been verifiably dempiistrated to conftm all relevant greimdwafer contamination for this determinatioiij and is defined by designated (inbnitoring) locations proximateto the outer peiimetCT of"contamlBstibn" that can and will besampledAested in the future to physically verify that all "coniammated"groundwater remains within thisarea, tod timt the further migjntib^ of"cbmaminated" groiradwater is not occurring. Reasonable allowances in the proximity of fe thbhitoring locations are permissible to mcoiporate forinal remedy decisions (Le., including public participation) allo^t® a limitedarea for natural attenuadbn.
4. Does "•
.X If no -skip-to #7 (atdientw ao"^'staSis code^h if " explanatioii and/oi referendi^ docuiHeintaiSbtt si^ ''^t^iripk)|f''#os-n#entor1sii^^ •
If unknown - skip to #8 and enter "IN" stattiseode.
Rntionaferand:ReferenceiS^: iiSe&atiaclM-iamfe
of Coiitiuadnated Groundwaiar UnderControl • EIJ.
5. Isl^^scbaise^f'^ontanunatei'*0t>UBdw^ vratetliMy to 1
r "level," and diere are no otherconditions (e.g., thenat^^ and mjmherj^^^ dischaiging cdntaarim^ OT eimRtorasaiM i^ichs^iiBcanfly ihcreato thepotaatiy for ipaeCieptable imp^ts to surfacewater, todiments, or ecprsy at ihese cpncentr^dhs)?
W^pr is not tmticipatM to i lediirictrtsv oreco^stem.
If np -(toe discJtegeof "contananated*groundwater into surface wtowis potentially sigmfiptotfr eotititide atordoc^eiiting: i) toe toio SHSPectodcPnceBtatiOti^ofeach cpptramaift ttotoaiiai ^xmdwater "level;" the value of the appropriate"level(s)," and if there is evidence that toe foncfntratjops are
greater than 100times theirappropriate groundwater"levels," the estimated total amount (mass in kg/yr) of each ofthese contaminants thatare being discharged (iMded) irito the stoftrce \tottohPdy toftoe ftme of toe d^eriiolinatjon), and identi^ if there isevidence that
i contoininaii& is increasiitg.
'If uulmpwtt -eriter "IN"statiK.eodeJti;#8i
Rationale and Reference(s);_
:'.:AS: ^^potheie)zcme.
inyironme »r (EI) RCRIS code (CA750)
6. tiie groundwatei- into surface water beshown to be"currently &cegtable^ (f^e^hot c^^ impacts to surfece water, sediments oreco-systems that should not be allowed toamtinue untilafimd
If yes -continue after either;1) identifying Ae Final Remedy decision incorporatihg ^
&r6iee\is^i^'sedtteiftei'ah^
iMfor ; water is;
tiveof r, sediments, wd eco^systems, until such time when a full
assessment and final remedy decision can be made. Factors which should be consider^ in the mtenrn-aisessmetit (where appipjpriate to help identify the impact aSSocia^ with diisdhariphg grm&dwater)'!^^^ sia&e wdtef size, flow, u^e/classificafiGh)T>abitats and ccmteininant idling liMts, other sourcesof su^
cOiiiiitosdnsI !;"»sweiias any otherfactors, such aseffects on ecological receptors (e.g., via bio-^says/benthic surveys or site-specific ecological Risk Assessments), that the ovi^eeing regulatoty agency would deem appropriate for making theEI determination.
If no - (the dikte#of'^ntamitiByd''grd»M acceptable") -sidp to#8 and enter"NO" status code, afta-documenting thecurrently
If unknown -skip to8 and^enter"f^Vsts^ code.
Rationale and Referenoe(s):^
* Note, becauseareas of inflowing groundwater can be criticalhabitat (e,g., nurseries orAermal refiigia) fhrm^ny «pgr!»fts,gppifi|Wi^e specialist (e.g.-eEOh:>gisfyshO^
water bodies.
' The urtdeBtandingof th^^iihpactsof cohtamih^d grduhdwater disdi^es ihtd^^^ is a f^idlydeveldpmg field andfeidewersi^encourag^ to Ibdktp thelat^t^danw^^^ mefltods and scale of demonstration to be reasonably certain thatdischarges are not causingcurrently unacceptable impacte to thesurftce watcB, sedimettts or eco-fystems.,
Page?
7. WingreinidMtermoiiitoriBg/measTire"niint<^(andsiff&ceTOt^^ necK^aiy) be collectKl in fte fetiiat! to verifythat (rontaminated gnjun4waterh^^ hoiiranttJ (or vertical, asnec^sary) diiaensions of the "existing area of contaminated groundwater?''
X If yes-eontihue after providingor citing documentation for plaimed activities or future sampling/measurement events. Specifically identify the well/m^in^eht locations which wUl be tested in the fiitiHe to verify fte expecrirtion (identified ini#3) lJiat groundwater eonteimihatioh will not be mig^ting horizonttlly (or vertically, as necessaiy) beyond file "ejdsting area of gtoundWater contammi^fe
If no - enter'^G''status code in #8.,
If unknown -enter "IN" statuscode in #8.
Rationale and Reference(s); See attached narrative
Pages
8. EI(event codeCA750), smd ot^Supemsdr (or ̂ propriate Manner)signature and date on the EI d^^inination beldw(^tach appropriatesuf^itingdocutnentation as well as amap of diefacility).
X YE - Yes,'^hEgradon ofGbftdaninal^ Gropidra^ been veriSed. Eased on a reviewofthe inforinatioh contained in this El
Choundwat«^ w"|lnderCQH^ Mvstic Station mm.. ....tocated-at;'^,l7?>\Iferd.Sto?et. -BostOBL i>dasseffihasett8 Sp^iiic^ly^ this deteitnination intEcatesthat dte migptiEm of"c»ntaniinated"gnsundwaibr is undn coiind will heccmducded to cohEnh t^ntantin^d "eus&g area of^ntandn^ed j^ deterpunation wiU be reevaluatedW^eii the Agencybecomes awareof significanttdtanges at the &Cility;
NO - Unacceptable migr^oR of contaminated groundwater isobserved ore^ecned.
IN - Mom infitnnidiOB is neededto make adetermination.
Ccpipletedby fstgnaitreV
Supervisor Isienature) farintV
fEPA Region orstate!
...fAl'fc::'.:. m.m-cA r IT, •
tMO&& f A
Contact telephoneand e-mEul nuntbsK
(name): (jdione#).
Esidroammtal (El) k€MS God£ of C^ntemiiiated Gro
The following narrative expands on the conclusions reached in each step of the Ehvironinental Indicator DeternMhati^ RGSS Gdde GA75d hfigration of Gontaniinated thoundwater Under Control, lleadihgs used iif notes correspond to the item ouml^rs in the determination worksheet. In this evaluation, Massachusetts Contingency Plan (MCP, 310 CMR 40.0000) standards were used to evaluate the risk (if any) that identified contaminants pose to hiBhan;receptors,^ .r*'..:
::BlCKGRGtIis(P ^
In 2009, Mabbett & Associated, Inc. (M&A) prepared a RCRA Facility AssessmeBt Report for the Mystic Station (Site) at 173 Alford Street, Boston, Massachusetts. The Facility Assessment Report included a comprehensive review of historic releases of oil and/or hazardous (OHM) identified at the Ae M&A listed one Solid Waste Mana^ment Unit (SWMU) and seven Areas of Concern (AOCs) where additional RCRA Faeili^ investigations (RFI) were recommended. G^ and Boston Generating subsequently refihed the incliision of the SWMU and two pf,|hBf,^Gfe|^;;^ggest^ipl®ntiaI"ie^^ reU^Hng, AOCs situated on property under direct control by Boston Generating. It should be noted that one of the open AOCs (AOC 19 - Release Tracking Number (RTN) 3-20199, Electrical Substation) is situated on property Independently operated and controlled by NSTAR Electric & Gas Company. GZA understands that NSTAR has provided information related to this AOC which hasfesnfied in aiihding of No FurdierAction requi^^
Ae table below doqunpntsthe EWMUsa^^ AOCs, and provides a description of the nature of the release and re>^nse aedons conducted to date. Ais table was included to provide a brief summary of the various SWMUs and AOCs. Please refer to M&A's Report for a more comprehensive description of the nature and extent of noted contamination. Justification for decisions made on the Environmental Indicator Determination for RCRIS Code CA750
;SWMU7 Waste Discussion AOC Name Managed
: Nuinber- , Oil Separator Pit/Former' •
Waste Oil 1 •••5 i'.
This SWMUincludes the area ofa formerfuel oil UST and oil/water separator wdiere petroleum impacted soils were
MCP Class A-3Response Action Outcome (RAO) Statement was Sled on August 10,2005. The Class A-3 RAO indicates that a Condition of No Significant Risk exi^ at theSite under current wd future conditions based on the implementation ofan Activity mid Use Limitation (AUL) savingas an institutional conteol IMting exposmes toany residual subsurface coa^ination. M&A recommended No Further Action.
SWML7 $WMU/AOG Waste . Discussion AQC Name MaBaged
Nomber SWMU2 RTN 3-10431 Corrosive In1994, approwmateiy 931,362 gallons of wastewater were
(Waste • Wastewater Treatment ^1irtdSurface was,frozen at Ihe tinie, limiting the potential for the Plant Storage release to impact soilsor infiltrate thesubsurfece; however,
, .Tank-fartn)'^ apprpsdinately 361 are believed to have flowed imo : the Mystic River. Based on remedial actions, a Qass A-1RAO was Issued on March 14,1994, indicating.that aCondition of No Significant Risk had been achieved, and that contaminants at the Site had been reduced tb baick^und. M&A re^^ Further Actiori.
•SWM/;3 Fomier Corrosive Wastetvatef Wastewater Testing in 1985 revealed the presence of a leak at the toe seam of Surface the liner. Closure activities were conducted, resulting inMassDEP Impoundmerit issuing a clean closure letter. M&A recommended No Further ,
Action. •tsw®)t.4 ^ Pbftneraad 'Gorfosive-' SWMU 4 includes the remaining portionsof the waste water
Garretit Wistevwit^i . rtreatmeirt.sy^iGtn. 'M!S;A,tecomm^ded:.Np;Fuid^ ^astevrater Haa^cms were no doci^ehted relea^s froni (hew Tr^imwit < Chemicais disciBsed above. System
'SWM0 5 " : Ceal AsftPile Goal Ash SWMU 5 concerns the potential, historicon-Site disposal of coal MiSlAretfoihthendedadMoii^^to
4sihiMons bet*veen USEPA and Boston Generating fHidingeFNo Fui^r Action, pi^pncpnrSjte C(^ wpi^d Ijkeiy haye:pccu!wd in-^ 8&9. The area was excavated aspart of the developmerrt of Mystic 8&9 (see AOC 7). The QassA-3 RAO indicates that a Coriditioh ofNO Sigtiificairt Risk erdistsat theSite under cun«^^ and fuhheeohdifiohsbased otithesiaipIemeAlaMono^^ serving asaninstitutional control limitingexposures to any r^idual sobsuri^ corltam ^
Fly Ash Basm,.,_ Fly.Ash This SWMU applies to a former flyash storage basin. No evidence of a release was noted. M&A recommended No Furth«-Aetfon.
AQCJ Unit? PetrOletan This AOC concerns the detection of petroleum hydrocarbons in Trans&nner Hydrocaiho sediments within asirtrtp associated with non-PCB tratjsforiaers Area ns near the Uriit'7Slain and iSidioii^^S^ The
AOC'Z , yiit'A •••Pettletirh- This AOC cohcerhsrept^Ma"greehish;liq!hd''i^ Building, Hydroearho exterior of the Urdt 4 feloilheafer rDorn. A:it|ipfg^^ Stained Areas .'IB. recOmmi^ed additionalassessment, discussiohabetweeiiU^
and Boston Generatingresulted in afindiog ofSfo FurfrserAction: Although the exact nature of the liquid cannot be documented, it is likely iat the observerwas dKcrtbing^^fl^^ (which would result in the noted conations and green color). General housekeeping practices in place at the time would have required the immediate cleanup ofthe condition described, and the materia would have been ihconforated into the
investigation program di#nut indicate the presence ofacidic w in this area.
RTO 3-12422 No. 6Fuel Multiple documented releases of \o.6 fueloil tosoiliwe Oil occuned fiom a pipelinethat transfers iuel oil betweenExxon and
the facility. Response actions haveresulted in aCondition of No Si^ficant Risk under theMCP, and a Class Ar2 jlAb \ra$ filed on August 28, 1995. M&A recommended NoFurther Acdon.
'.AlSa^Sne^^' ' ~ No. 2.mi A series of former fuel oil USX were located along the southern USTs property. Closure docuipeatalion fUr tiiese^^^U^ not available.
Oil iA^ysis ofspils and groundwater conducted ah part ofGZA's recent subsurfece investigatipn progiamdidnot mdicate the presence-ofpetroleunjfedtpca^nSiaiwyelViGP regulatory limits.
sSpiltpf ...s^ Fuel Oil AQUi ^ cgnceras die 1976releaMofapproxiinate!y 9,000 galltms :!UnlancnTOi pf ̂ feelpU, Aithgtigha spedfic tecatipn for fliis release was not
iPpteApripr repprts itdiKitedthat^to release"likely pccuned near pArtpKigeitaQks, pipelines,v^ odier&el handling equipthent" Although M&A recommended additional assessment, discusadds betwden USEPA^M^^ Boston Generating resulted ina finding ofNoFurther Action. Based on diehistoric ppdatipnsigt the Site, and a reviewof previous such releases, the most likely locations for a release of this magmtude would be Sbhi the underground and above ground pipeiines, bulk fuel aorage tanks, the storm drain system or fire suppressirai system all formerly location in theeastern portion of the Site in thearea now occtgil^ by Mystic 8&9Station. The area wasexcavated as part of thedevelopment of Mystic 8&9 (see AOC 7). The Class A-3 RAO indicates thata Condition of No Significant Risk exists at the Site under current and fiiture conditions based on the implementation of an Activity and Use Limitation serving as an insfifution^ control limiting exposures to any residual subsurface contamination^
RTM3-«a23, No. 6 Fuel AOU 7 refhto to a series of historic release which occurred in the RTN 3-18553, Qii, area of the current Mystic 8&9 fecility. Extensive investigation RTN 3-18717 PhUial^e and remediation were performed in conjunction with these
releases, but complete closure could not be achieved due to the presence of buildings and equipment in active use;however, duruigShe development residual contaminated soil andgiMtodwat^ wCTe remov^fiOni the at«aand heatedor deposed dltoffiSite T^aiea^^ eitoavated as development of Mystic 8&9. A Class A-3 RAO was filed on Aupst 10,2005. The Class A-3 RAO indicates thata Gpndftion of No Significant Risk exists at the Site under current and future :pEmdhtons|]a|sei| pnthe unplenientofipn of an AUL serving asan
;• '• .it institutional control limitingexp<»mes toany residual subsurface - (tontainjhdtioni .M&A recommended No Further Action.
•. SWMU/ Waste i)BCBSSWtf. " • AOC Itome Managed
Nttmber •113C¥ RTN 3-12140, No. 6 Fuel AOC 8 refers to residual NAPL present near Tank 1 and 2,
RTN 3-17789 associated widi historic releases of No. 6 fiiel oil. Structural; •• elmentis-dflie fedhty preclude the excavaliohofihe rB^^^ fuel oil; however, a Class C RAO, aTemporaiy Solution under tihe MCP indicting that acondition ofNo Substantial Hazards exist at the Site,was submitted on August 8,2000. Post Class C RAO monitoring has revealed declining NAPL thicknesses, and recent
. i" • groundwater sampling hasnot indicated the presence of petroleum hydrocarbons above MCP regulatory thresholds. M&A recommended No Further Action.
Ethylene •"This- AOC refers to a'Measebfeffiylehti'i^ebfvyuGh-w^ A^ StO^e Glycol whtdhedwnthtnthephrhplodmbf M&A Basin Pump recommended No Further AotiOa Rbbm
AOC 10 •••Rrif'3-1984F"''- ':Ndt6:fuel. " This AOC concerns die release of No. 6fuel oil to a utility trench•*- foc^ iffths^oorpfthotJMtl biul^^ Mystic River. Response actions contained the release and remediated impacted receptors. M&A recommended No Further Action as aClass A-1 RAO was filed on July 14,2001.
AOC 11 'No^-tW'- This AOC concerns the release of t^rexithitely187of 'Oil-''' No. 2 fuel oil to pavement •Th€;rel^e'Was'reihedieted,:ahd''^
Glass A-1 RAO was filed on March 21.2003. M&A
AOC 12 W2"»el • • •• This AOC concerns the release ofapproximately 25 gallons of No. Oil 2 fuel oil to the bermed area of Tanks 1 and 2. The release was
remediated, and aClass A-1 RAO was filed on December 7, 1998. M&A recommended No Further Action.
f ^i^lbrbeth Tetrachloroe AOC 13 refers tothe detection of fefi^Woroethylene in ylene in groundwater duringclosure activiti^ i^^ciab^ wiW Oroutdvper surfece impoundments(See SWMU 3) inthe early 19^s.
CohcenMlbiis detected &e belowthe current^ applicable MCP re^^ty threshp^^^ 1M&A recommerided additional assessment for^tiiis AOC^ GZA has iPccntly inst^ mbhitotih&t^in^fi# area to assess;^ groundwater analytical resultsdid not indicate concentrations of volatile organiccompounds (VOCs) above laboratory detection
and pavement. Soil sampling was conducted in former locations of the remaining transformers. Preliminary results indicate the presence of PCBs in shallow soils above MCP regulatory thresholds at Transformers 3 and6. Soils around Transformer 5 •were less than the Rqrortable Concentrations under MCP. An MCPElaidTMtial Ste InvestigatkmpSI) Report pm^ant to 310 CMR 40.0480 and Tier11 Classification pursuant to 310CMR 40,0560 was subrititihd to MassDEPdrtJDdcern^ 7.2011.
f ,,SWMU/'.lift ,, Mwaged; ,
Number AOC 15 RTN 3-13744 HydraulicHydraulic In 1996, approximately 19gallons of hydraulic oil were released.
OilOil rcsuiung'lua i^^pynac ayUvub were conducted, and aClass A-1 RAO was is»ied on July 10,1^6. •M&AiVcGininerideiNoFur^er'Acfit^s:;-,,, ,
AQCI6 RTN 3-17445 93.7% In 1998, approximately 10 gallons of sulfuric acid was released Sulfuric from a foiled valve. Response actions were conducted, and a Class Acid A-2 RAO was issued on December 16,1998. M&A recommended
No Further Action. :;Rii-.3r^l®4ii- '•lb*'-" • In 2003, a release of approximately 30 gallons of non-PCB
MODF transformer oil Qctmiiifc :Resp|iseia#mS,wete;cofida^ Class A-2 RAO was issued on June 23,2003. M&A recommended No Furifliw:Action
A0C18 RTN3-22863 No-PCB AOC 18 concerns the release of ^pioidmately 100 gallonsof MODF MO^'whbhi;iheJlS;kihw6^
operated by NStar. The release was remediated and a Class A-2 RAO issued May 28,2003. M&A recommended No Further Action. ; ..r. fJi' ;
A0C19 ^ RTN 3-20199 RGB and t :AiGDR';r';
AC^T-9,conc#fo^jp«aert^fen;W
NSt^. M&A initially recommended further assessment;however, NStar personnel prpwded USEFA with supplemental information documenting appropriate handlingof former PCB ^paratus, lesutting ina ̂ ingiof No Fu^
stability may allow more expedited closure of the Site. The proposed
Soil in IGCMOM of Ibrtlter t^sfb^ 14) are beihf iiwestigated under the MCPs On July 14,2010, a series of borings in these areas were advanced using a vacuum excavator. The goal of these explorations was to collect soil samples from a depth of below 6 feet, to assess for residual PGB contamination^howeveri imuitiple boring atten^jte inet with refusal and no boring loeaiions could fee cleared for the Tram and 2 area. PCBs in iheJldw soil above MCP regulatory thresholds were found in locations dfibtmbf ttahijlanfi^ not
appear that groundwater is affected. Further mvestigation will be completed aspart of a Phase11 Cphipriehensive SitdA^esph^t fCSA^^ is due to be completed by December7,2013.
3.,^
The ideoMfied eOistaaTiirtdoh consists of 6 fuel oil). Due to the viscosity of No 6 fuel oil, coupled with the ongoing response actions under the MCP, migration of the NAPL plume is not expected. Additionally, recent groundwater testing fiom the affected area has indicated that no volatile petroleum hydrocarbons (VPH) or exfractable petroleum
theifesing:#.;; Temt
Recent-grouiidwamr testingi^m thei 3 indfcsdes that, no yPH or CQmpounds weie deSdcted above laboratory method detection limits. As no dissolved phase plume is present, discharge to surface water is not expected. Documentation of the testing is included as part of GZA's September 2010 Periodic Evaluation of the Status of the Temporary Solution.
Groundwater has not been tested in the area of AOC 14; however, it q>pears,that PCB is limited tp shallow soil.
5, Ongoing Groundwater Monitoring
Lpng-term groundwater monitoring has, and will continue to be, conducted under the MGP, and documented in setniannual Post-RAO C Operation, Maintenance and Monitoring Reports. As requited by Ae MCP, a Periodic Review of die Temporary Solution is required every five years. The most recent Periodic Review in 2010 indicated that the appropriate Site-specific monitoring program includes the following activities: gauging/recovery of NAPL on a quarterly basis; cpllection of groundwater samples for analysis for VPH and EPH once per 5-year review period; ;ar«pevalu|aidhbfte]^)teirdalihian^s;iif;Site^t^^
Reeeht moilitermg lisults demoiistriate that the Site coiidldons rertiam^^t^^ described in the Class C RAO; NAPL was only detected in one monitoring well (ABB-MW-203), and NAPL thickness in ABB-MW-203 was below 14 inch during Ae past two quarterly monitoring events. Based on Ae dssence of NAPL in downgradieait wells GZ-301 and ABB-MW-204, LNAtii does not ai^ear to be migmting^m A^ However^since LNi^L thickness is intermittently detected above Ae MCP Vi-mch UCL in ABB-MW-203 a Permanent Solution cannot be achieved at Ais time. The periodic gauging and recoveryevents will continue to monitor NAPL Aickness and will evaluate options for achieving a Permanent SolAion RAO during the current periodic review ]
