Nuclear Metals, Inc. Superfund Site

FS Presentation

February 12, 2013

Presentation Outline

• Schedule • RI / Risk Assessment Results • FS Outline • Soil / Sediment Remedial Alternatives

• Groundwater Remedial Alternatives • Vapor Intrusion Remedial Alternatives

• Appendices

Schedule

• Provide RI Report (and EPA comments) and Risk Assessments for public review

• Provide FS Report for public review

• Prepare revised FS Report.

• EPA submits prospective remedy to NRRB (April 2013)

• EPA prepares “Proposed Plan” that identifies overall remedy

• EPA issues Proposed Plan for comment (~June 2013)

• Public Meeting on Proposed Plan (~July 2013)

• EPA issues “Record of Decision” that sets forth required remedy for Site. (September 2013)

Legend

Site Boundary

AOI Outlines

Soil Boring

Surface Soil

Sediment

de maximis, inc.

6 MACTEC N

GEOSYNTEC CONSULTANTS

•

~$

•

$

•

A01 14 SURFACE SOILS

• •

• •

• ~ •

• •

•

Sphagnum •og,,,..

:a:

•• ••

•

•

Rl Sampling Locations Phase 1A, 18, and 1C

Nuclear Metals, Inc. Concord, Massachusetts

Remedial Investigation / Risk Assessments Results

• Extent of contamination in soil, sediment, surface water and groundwater delineated sufficiently to proceed with risk assessments.

• Surface soil and subsurface soil exceeding acceptable risk levels constrained to certain areas within Site boundary.

• Sediment exceeding acceptable risk levels constrained to portion of bog and cooling water pond.

• Groundwater contamination exceeding acceptable risk levels exists on-site and in defined area off-site.

Areas of Soil or Sediment with Unacceptable Risk

Unacceptable Risk Area

(where remediation will be evaluated in

Feasibility Study)

Distribution of MCL Exceedences for VOCs and MADEP (GW-1) Exceedances for 1,4-Dioxane in

Overburden and Bedrock Groundwater Most Recent Data through November 2009

Nuclear Metals Superfund Site Concord, Massachusetts

Areas of Groundwater with Unacceptable Risk (VOCs)

FS Outline

Section 1 –

Section 2 –

Section 3 –

Section 4 –

Introduction, background, nature and extent of contamination, risk assessment results

ARARs, RAOs, GRAs, PRGs, areas and volumes of media, ID and screening of technology types

ID and screening of technologies and process options

Detailed and comparative analysis of soil and sediment remedial alternatives

FS Outline (continued)

Section 5 – Groundwater technologies summary

Section 6 - Detailed and comparative analysis of groundwater remedial alternatives

Section 7 - Detailed and comparative analysis of vapor intrusion remedial alternatives

Excavanon Depth (ft) Fonner Acid Drain .. 1.00 Natural Gas dl 1.01-2.00 Cooling Water [] 2.01-3.00

Diverter Potable Water SupplyJFire [] 3.01-4.00 Drain Manhole Former Fire .. 4.01-6.00 Electric Manhole Sanitary .. 6.01-8.00 Floor Drain Parking Drain .. 8.01-1 0.00 Hydrant Unes Drain to Cooling Water Pond If] TB.D. by remedy selection Manhole Former storm Drain .:::1 Remove all metal &soil to Outfall Unknown AreaName Valve Site Boundary (Approx.)

~ Cooling Water Recharge Pond

CJ USTs lndustnal COurtyard Area CJ Septic Sys1em Sw'eepingsArea

Northern Pavement Drain

t:2l Trailer

Soil and Sediments Exceeding PRGs

COoling Pon d 1

/ p' (

I

"""/ Q MW-SOB

l AST-1 i

'~ • • Q MW-S23

~ -~ . :--) ---

( -----0 • _..-

---------- HA-10 . ---------______ __... 0 HA-10A ~-----_ __.v----·

.---

; t PZ-RI-002

PZ-RI-802

L

sphagnum Bog

Legend 9 l.t:<'i'bilg'II'SI

+ PiexMdP;r

f:' Stm'GI;a~Q!:

() 03r>:U>,..,.,.F'Ioi,~loo::ll.,.,

o~Rel<t &, 'M1;1nao CJ~:a~rto:~VIIIt::r

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od~CC

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..... 13o:UI(J,o!Qef1CNIQ~edon

To1al Uranium. Most Recent 09t:acta

Q <l~L

. l.Ol·lO~L

0 10.ol-~0!JD'L

0 ~0.01-ZO!Jg'L

• ~zo.Ol!-VLI.CLEu:.....mn<einO.Oeltudon

11.Q9 10.0

,.,,

Total Uranium Concentrations_ in . Overburden Groundwater Near Holding Basm

Historical Data through May 2011 Nu::lear P.,tetaE Super1un:l SiB

Gon::ord, tv'Bl:isa.cflusetll:i

-~~~--~==~~---:~~ 25 so 100 150 200

Geosyntect> consultants

---¥-de maximJ.'s, inc.

1.4.2

Depleted Uranium in Overburden Groundwater

legerd

0 AotM:CM:Oibuld<tnCtf'Pif-1

0 B<!:dotOOkf-.. d~,..,.

Choubuden f-•Gi-~::::; t,t- OCEabo""" ~CliriOwlburJ•n !::::; 1,,..0io~neab-~AOI!P"Otlrlkr, V.•rGuldlh lnO....!Ourd•n

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c::::J lil illo Bo un:la'f

~Wiil02 0\erburden~onit>ri-o.il"""ll

VOC and 1,4 .. Dioxane Plume Areas in Overbu rden a nd Bed roc k Groundwater

MOst Recent Data through 2011

Nu:lear Nletals Su~rfund Site rvb.ssachusetts

Figure

1.4.3

VOCs and 1,4-dioxane in Overburden and Bedrock Groundwater

0 50 100 200

Uranium Conoentretlon!lln Bedrock Groundwoter

Historiool Dolo thr<XJgh May 2011 Nuclear Metals Superfund S~e

Concord, Massachusetts

Uranium in Bedrock Groundwater

+ Piezometer

• StaffGaupe

• ActiVe Overburden Suppty Wen

• Former Overburden Supply Well

• Former Bedrock Suppty WeH

PublicWatM ~ 'lllell

'Netlands

SurlaceV'IAiter

RivO<

SepticAetds

Si~ Boundaty

D .,.,"" ~s Exceeding Vapor Intrusion Screening Levels

Chloroform· 0.71 ~

VC · 0.14 1J~

VOC. detected in overburden 101 at concentrations geatef than anatytical reporting limits

"" "" ...,

Areas Exceeding Vapor Intrusion Screening Levels

Nuclear Metals Superfund Site Concord, Massachusetts

Figure

1.4.5

Potential Vapor Intrusion Areas

FS “nuances”

• Extensive use of tables – review needs to incorporate tables in concert with text

• Rather than go through detailed analysis for each media, then comparative analysis, this FS presents detailed and comparative analysis for soils / sediment, then groundwater, then vapor intrusion.

• Alternatives for soil remediation limited to excavation and containment (either on-site or off-site). Saturated soils acting as source material evaluated in soils alternatives.

• Groundwater alternatives address overburden DU plume, overburden / bedrock VOCs and 1,4-dioxane, and bedrock U plumes separately.

FS “nuances” (continued) • “Green” remediation considered in detailed and

comparative analysis.

• Costs for RD Work Plan and POP, which will detail pre­design investigations and design process for all media, are carried in only the soil and sediment alternative costs,

• Costs associated with ICs are carried in only the Groundwater – VOC and 1,4-dioxane alternatives. Costs incorporate the potential ICs applicable to all media. Higher costs expected to obtain off-property easements that would be needed to implement hydraulic containment and treatment are carried in that alternative,

• Costs associated with performing five-year reviews are carried in the Groundwater – Depleted Uranium alternatives.

Soil and Sediment Remedial Alternatives

• SS-1

• SS-2

• SS-3

• SS-4

No Action

Excavation, Stabilization of Saturated Soils within Holding Basin, On-Site Containment, and Site Restoration

Excavation, Containment of Holding Basin, Some On-Site/Most Off-Site Disposal, and Site Restoration

Excavation, Containment of Holding Basin, All Off-Site Disposal, and Site Restoration

Note on Soils / Sediments Remedial Alternatives with Respect to Holding Basin

Excavation of all impacted soils below and immediately downgradient of the Holding Basin (down to bedrock) was considered in the development and screening of technologies (Section 3.1.4) portion of the FS.

Conceptually, this would be a 90’ deep hole, removing ~95,000 cy, requiring extensive shoring, dewatering, and water treatment. This aspect of the remedy alone would be > $110,000,000.

The expected technical difficulties and costs associated with this approach are grossly disproportionate to the effectiveness, so it was screened out of further evaluation.

650 600

LEGEND

D·.-. .J9~:" Gc«ompo-..iiC

60 tnl HO~ET~'( !Ml11 (l<gt~!•b 1''" Geosyf\tttl< Ci) .f'IE((J(2-t•clt~

6~m1ryC:ctiiMt~t~

6"' G.:.s 'h'l:irqA~.)tt

550 500 450

Zone 1 -Uranium> 30 mg/kg in Vadnose Zone Soils Zone 2 - Uranium >30 mg/kg in Saturated Zone Soils Building to be demolished

Distance units depicted are feet (ft)

Stratified Drift

400 350 300 250

12~ S.nd Sed~ Prim.ll)' C~K'OO C~O«;MOOS1!~

(rtK("COII8ilb'l~tli· ~rtcrA:I'd._.Df>Fin5 .. 01'o6•F-~IIg~!l')

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6~ l!e<otr~ S..ll (!,JOe

- 20

- 0.0

--20

- -40

- -60

200 150 100 80 0

SS2 -Containment Facility Elevation View Feasibility Study

Nuclear Metals Superfund Site

Name: Fig4.3.2_CF _profile Date 1113012012 Author. HGaedy Project No.: 3215 Reviewed by: VR

SS – 2 Excavation, Stabilization of Saturated Soils within Holding Basin, On-Site Containment, and Site Restoration

SS – 2 Excavation, Stabilization of Saturated Soils within Holding Basin, On-Site Containment, and Site Restoration

• Excavate and place approximately 77,000 cy of site soils and sediments into an on-site containment facility;

• Holding Basin – Excavate and place unsaturated zone within

containment facility

– Stabilize in-situ saturated soils within the Holding Basin footprint;

• Construct on-site containment facility; and • Restore site Costs: Capital: $35,880,000 O&M (NPV, 200 years, 7%): $ 7,465,000 Total: $43,345,000

• --m

SS3. Vertical Barrier Walland Cap Feasibility Study

Nud(tiY Mc.-tt1.s SUporfl.l'ld S.to

Zone 1 • Uranium > 30 mglkg in Vadnose Zone Soils Zone 2 - Uranium > 30 mgl kg in Saturated Zone Soils Zone 3 - Uranium > 30 ug/1 in Groundwater Building to be demolished

125" Asphtt.th Su1¥.e 1\ ~ Ao;ph.lu!l [l._o;p

S"A<J9"'1•"''-'>.,

30.75." (0\ler Fill {StatiC 8a'T!er)

~>'•Hid'~~ G::u.UH!I.IO\dC

60 m l HOP::l<!xturcc &~'T!br.:M

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- 20

-00

- -20

- -60

-00

-100

SS3 - Vertical Barrier Wall Elevation View Feasibil ity Study

Nuclear Metals Superfund Site

Name: F ig4.3.4_HB_proflle Date: 11130/2012 Author. HGaedy PrOJect No: 3215 Rev~dby: VR

SS – 3 Excavation, Containment of Holding Basin, Some On-Site/Most Off-Site Disposal, and Site Restoration

SS – 3 Excavation, Containment of Holding Basin, Some On-Site/Most Off-Site Disposal, and Site Restoration

• Excavate approximately 77,000 cy of site soils and sediments;

• Dispose off-site most soils and sediments; • Holding Basin

– Placement of ~8,500 cy of least impacted site soils to bring the Holding Basin up to grade

– Install containment wall – Install impermeable cap over walled area; and

• Restore site. Costs: Capital: $56,927,000 O&M (NPV, 200 years, 7%): $ 4,506,000 Total: $61,433,000

Bldg· C r .. ···········-······: ~--------·- .

Stratified Drift

Zone 1 • Uranium > 30 mglkg in Vadnose Zone Soils Zone 2 - Uranium > 30 mgl kg in Saturated Zone Soils Zone 3 - Uranium > 30 ug/1 in Groundwater Building to be demolished

125" Asphtt.th Su1¥.e 1\ ~ Ao;ph.lu!l [l._o;p

S"A<J9"'1•"''-'>.,

30.75." (0\ler Fill {StatiC 8a'T!er)

~>'•Hid'~~ G::u.UH!I.IO\dC

60 m l HOP::l<!xturcc &~'T!br.:M

(";1"'\")'(.}'f'l!hNi<(l.ly l !fiC'te'l'}.i"("L'Y

G:r, Vt"ntu~g G<'O<O~tt"

6"G.'t\~111'1)1\!j1Jr(l(l.ltC'

SS3 - Vertical Barrier Wall Elevation View

Name: F ig4.3.4_HB_proflle Date: 11130/2012

SS – 4 Excavation, Containment of Holding Basin, All Off-Site Disposal, and Site Restoration

SS – 4 Excavation, Containment of Holding Basin, All Off-Site Disposal, and Site Restoration

• Excavate approximately 77,000 cy of site soils and sediments;

• Dispose off-site all soils and sediments; • Holding Basin

– Use clean off-site soils to bring to grade – Install containment wall – Install impermeable cap over walled area; and

• Restore site. Costs: Capital: $62,413,000 O&M (NPV, 200 years, 7%): $ 4,506,000 Total: $66,919,000

Groundwater Remedial Alternatives DU in overburden: • DU-1 No Action • DU-2 Source Isolation (SS-2, -3, or -4) with Hydraulic

Containment and Ex-situ Treatment

• DU-3 Source Isolation (SS-2, -3 or -4) with In-Situ Treatment

VOCs and 1,4-dioxane in overburden and bedrock: • VOC-1 No Action • VOC-2 Hydraulic Containment with Ex-situ Treatment

• VOC-3 Monitored Natural Attenuation / Long-term monitoring

Uranium in bedrock: • UROCK-1 No Action • UROCK-2 Hydraulic Containment with Ex-situ Treatment

• UROCK-3 Long-term Monitoring

Source Area Vertical Containment Barrier

Holding Basin Cap

Legend

~ Proposed Pumping Well .., Proposed Mon~oring Well

~ Monitoring Well

... Piezometer

• Former Bedrock Supply Well

---· Uranium MCL Exeeec!anee (>30 ~giL)

0 sae Boundary

N

~ A

1m Source Area Vertical Containment Barrier and Cap

- Estimated Hydraui c Capture Zone (Note 1)

___.. Groundwater Hydraulic Gradient

Notn I Thttlt.lwMedU~P 110ne M~'!.ane•ncaonQ::t"ol apptllliiNtety 18 gpm, b~ed on a hydtalulc: orNtnl 010 011.;) "rd'~C CDt\OJdMt'f ot 31 Wdav • .a~""""**" of 115 t anct a p1....,.. rf'Kble$6. ot 42ft 7 ftr k:Jcdflons ol COtM'ya"'Ct ptpng. lnl~ftl bu4dlng itftd lhthargt llnr co be dtctm'Wied Oumo tf"f'NOI~ d~')n 3 SoutH 1D.It10n ~nc._.drtt t-lo.,•ng 8-H•n Cap and Vetlltal8.arntr

DU-2: Source Isolation with Hydraulic Containment

for Depleted Uranium in Overburden

DU-2 Source Isolation (SS-3/4 shown) with Hydraulic Containment and Ex-situ Treatment

DU-2 Source Isolation with Hydraulic Containment and Ex-situ Treatment

Institutional Controls to prohibit future use of impacted groundwater.

Hydraulic Containment and Ex-situ Treatment - groundwater extraction and treatment to hydraulically capture groundwater containing DU (>MCL) and ex-situ treatment of the extracted groundwater to remove metals and organic compounds, and discharge of the treated effluent to the Assabet River.

Long-term monitoring of groundwater elevations to confirm hydraulic capture, monitoring of groundwater quality to assess concentration decreases and monitoring of system influent and effluent to meet permit requirements.

DU-2 Source Isolation with Hydraulic Containment and Ex-situ Treatment

Pore Space Area / Volume = 0.92 acres / 253,000 ft3

DU Mass addressed = 6.0 kg

Costs:

Capital: $ 923,000 O&M (NPV, 200 years, 7%): $ 9,086,000 Total: $10,009,000

Source Area Vertical Containment Barrier

MW·S18

Holding Basin Cap

Legend

Proposed Reactive Zone Monitoring Well

e Proposed Media Injection Point (Apatite)

~ Monitoring Well

+ Piezometer

e Former Bedrock Supply Well

Uranium MCL Exceedance (>30 ~giL)

c::J Site Boundary

~Source Area Vertical Containment Barrier and Cap

___. Groundwater Hydraulic Gradient

Notes Source Isolation Includes Holding Basin Cap ana Vertical Barrier

Reactive Zone 1 (RZ-1) 3D Apatite Based Media Inj ection Points at 25 n: radii spacing to minimize occlusion due to proximity to source zone

Reactive zone 2 (RZ-2) 30 Apatite Based Media Inj ection Points at 14 tt radii spacing to capture remaining mass nux from RZ-1

Reactive Zone 3 (RZ-3) 30Apatlte Based Media Injection Points at 7 rt radii spacing to act as secondary containment for residual uranium not capbJred in RZ-1 and RZ-2.

DU-3A: Source Isolation and In-Situ Treatment with Apatite

for Depleted Uranium in Overburden Nuclear Metals Superfund Site

Concord Massachusetts

10 11o--•sll[o===-----~1 0~881

------¥-de maximis, inc.

DU-3aSource Isolation (SS-3/4 shown) with In-Situ Treatment

rtf P.W-7A

HA<l

Source Area Vertical Containment Barrier

MW-518

Holding Basin Cap

Legend

<9 Proposed Reactive Zone Monitoring Well

e Proposed Media Injection Point (Apatite)

0 Proposed Media Injection Point (Zero Valent Iron (ZVI))

~ Monitoring Well

-+ Piezometer

• Former Bedrock Supply Well

---· Uranium MCL Exceedance (>30 ~giL)

c:J Site Boundary

1m Source Area Vertical Containment Barrier and Cap

____.. Groundwater Hydraulic Gradient

Notes· Source Isolation includes H aiding Basin Cap and Vertical Barri er

Reactive Zone 1 (RZ- 1): 30 Apatite Based Media InJeCtion Points at 25 n radii spacing to minimize occlusion due to proximity to source zone

Reactive Zone 2 (RZ-2): 30 A patite Based Media Injection Points at 14 n radii spacing to capture remaining mass nux from RZ-1

Reactive Z one 3 (RZ-3) 30 ZVl lnjection Points at 7ft radii spacing to act as secondary containment fa· residual uranium not captured in RZ-1 and RZ-2. ZVI occlusion not anticipated at

I due to i I in RZ-1 and RZ-2

Treatment with Apatite and ZVI for Depleted Uranium in Overburden

Nuclear Metals Superfund Site Concord, Massachusetts

1 0."o--•sll[o===~-----~10~eet

----¥-de maximis, inc.

DU-3b - Source Isolation (SS-3/4 shown) with In-Situ Treatment

DU-3 - Source Isolation with In-Situ Treatment

Institutional Controls to prohibit future use of impacted groundwater.

In-Situ Treatment via apatite and/or zero valent iron permeable reactive barriers (PRBs). This remedy component results in sequestering uranium both in sorbed and mineral precipitate forms. Pilot testing would be conducted during remedial design to select reagent.

Long-term monitoring of groundwater quality to assess concentration decreases due to dispersion, dilution and volatilization (MNA).

DU-3 - Source Isolation with In-Situ Treatment

Costs Capital: $1,263,000 O&M (NPV, 200 years, 7%): $2,933,000 Total: $4,196,000

Costs are for DU-3a – the slightly more expensive of the two approaches

Pl'l)0(1!::>8d f!xllacbOn W&U in 8eCSrock

Pr(lpOstd Eli:lrAetiOI\ Wttlln 0Ytl'bUrd4fl

8 Mon•1onn9 Wtll

P18lOM919r

- ErotJmat9d Hvdr;tuhcCaPtuf'9 Zono lor Extroctton Woll•n 8Gdrock

Eshmeted H~dl'\\uhe Captu,. Zont tor F.lCtr•chOn weu 10 Overburden

~~~~ ' . .. !"'

" ""m ~~ .. ~r:.t •

\ \

\

., -.

L :I 1. 1- OCE &bove MCI. 1n Ove!'bufden

L : l 1,4·0toxan• ebov~ MAOEP Onnking Wattr GUidehnt in O~trburdtn

0 t.4~Diorani' above MAOEP Dnnk•na Wat•r Gutef&hl"'t •n 8tdrork

L_ :I PCE above MCL '" Overt>u~d&n L. :I TCE obovo MCLin Ovorb<irdon

0 TCE above MClin Sidi'O¢k

~ WiH8nds

Smftlct Water

D Stft 80Uf'ldiry

"*~ to~ Ovortturnen MonJonno weu

t~W.U$01 U&drock Mon1tonno Well MW· IO Non 1\JtiG!Iontll Monttonng Well

~tly<1r'.lUIIC graGtntorO OU • .)I'IyQfAfiC (Of'IOXWCVOI' • 3nl01f. apunewlcttnot200 rtal'lltaplumt D"III:Wis ct50 n OflatfjarauiJC Qf~l!f'l(of0004.~ cooouctMcyot 02)ft/OJy. aptl.lmt W!OO'!Of4JOR•no 1 pUnt u.:t<tten(f(z.51t.

N

i VOC-2: Hydraulic Containment for

VOCs and 1,4-Dioxane in Overburden and Bedrock

Nuclear Metals Superfund Site Concord, Massachusetts

20~0 .... ~,0;0====~ ......... 2~~·~

2-dt ma.ximlr, 111c.

VOC-2 Hydraulic Containment with Ex-situ Treatment

VOC-2 Hydraulic Containment and Ex-situ Treatment

Institutional Controls to prohibit future use of impacted groundwater.

Hydraulic Containment and Ex-situ Treatment - one groundwater extraction well in deep overburden and two groundwater extraction wells in bedrock in the area between Main Street and the Assabet River and ex-situ groundwater treatment building to treat 1,4-dioxane (e.g. advanced oxidation), then discharge the treated water to surface water.

Long Term Monitoring of groundwater elevations to confirm hydraulic capture, monitoring of groundwater quality to assess concentration decreases due to dispersion, dilution and volatilization (MNA) and monitoring of system influent and effluent to meet permit requirements.

VOC-2 Hydraulic Containment and Ex-situ Treatment

Pore Space Area / Volume = 12.39 acres / 10,034,000 ft3

(area is for 1,4-dioxane overburden, volume includes bedrock)

VOC mass addressed = 2.11 kg 1,4-dioxane mass addressed = 3.41 kg

Assumed time to clean up (off-property) = 30 years

Costs: Capital: $4,386,000 O&M (NPV, 30 years, 7%): $4,291,000 Total: $8,677,000

VOC-3 MNA/Long-term Monitoring

Institutional Controls to prohibit future use of impacted groundwater.

Long Term Monitoring for VOCs and 1,4-dioxane to evaluate concentration decreases due to biodegradation, dispersion, dilution and volatilization (MNA).

Assumed time to clean up (off-property) = 30 years

Costs: Capital: $ 904,000 O&M (NPV, 30 years, 7%): $ 811,000 Total: $1,715,000

Legend Wellin Roc~ osod Exvocuon "'I Prw

~ Mot11tonng W~l emratlons (IJg/L) 2011 Uranium Cone May

• 003 I 00

• 1 01· 10 00

0 1001 -3000

• 30 01-100000

• 100001 600000 tZono(Note1) Hy

orauhc Gapcur (~ NGVD) - Esameteo Eltvlllon Contour NGVD)

2008 Grounclwtttr atlon Contour (h 123- Apnl Grounclwot•r Eltv I 2008 Esamotoo rt<lotnt

123- • Apn .,...,., hydr•M g CL o1 ~0 ~ ----+ A~>t" 2008 Groun .,~m tx(tfeb •n• M

ADPtoxwn•• •n Yw1liti tlf

c:J RM>r

D S!IoBounelaly • .-"'""'""'""'=~•• CW.4llUli'I.IM ot ~~ ~a;..., ..... '":"'"'~ .,....,.~~ • .;..»at ~~•-go 1n0 lObe 15 •·:!:!..':ne~17&"-:_:t:.erct1Ut,;ng NI:Jay,ap. GICOfMYW'Ce • -----:-:-;::::;~t 2r ........................ _ _ • ent ....,_ .... "~~ . Contamm

UROCK-2: Hydrau:~c Bedrock for Uranium s perfund Site

Nuclear M~ta~as~achusetts Concor_. ____ _

UROCK-2 Hydraulic Containment and Ex-situ Treatment

UROCK-2 Hydraulic Containment and Ex-situ Treatment

Institutional Controls to prohibit future use of impacted groundwater.

Hydraulic Containment and Ex-situ Treatment - includes installation of one groundwater extraction well in shallow bedrock at the downgradient end of the isotopically natural uranium plume (near MW-BS28), construction of a treatment system to remove uranium from extracted groundwater, and discharge of the treated water to surface water.

Long-term Monitoring of groundwater elevations to confirm hydraulic capture of the uranium plume in bedrock groundwater, monitoring of groundwater quality to assess uranium concentration trends, and monitoring of system influent and effluent to meet permit requirements.

UROCK-2 Hydraulic Containment and Ex-situ Treatment

Pore Space Area / Volume = 7.99 acres / 233,600 ft3

Uranium mass addressed: 0.57 kg

Costs: Capital: $1,163,000 O&M (NPV, 200 years, 7%): $6,387,000 Total: $7,550,000

UROCK-3 Monitoring

Institutional Controls to prohibit future use of impacted groundwater.

Long Term Monitoring for uranium to evaluate concentration decreases due to dispersion, dilution, and precipitation.

Costs: Capital: $ 904,000 O&M (NPV, 200 years, 7%): $ 811,000 Total: $1,715,000

Vapor Intrusion Remedial Alternatives

VI-1 No Action

VI-2 Institutional Controls and Development Restrictions

VI-3 Institutional Controls and Vapor Mitigation

VI-2 Institutional Controls and Development Restrictions

Institutional Controls would be implemented to limit construction of new buildings to areas where significant VI is not expected.

Costs: Capital: $ O&M (NPV, 30 years, 7%): $136,000 Total: $136,000

VI-3 Institutional Controls, Future Investigation and Vapor Mitigation (if needed)

Institutional Controls would be implemented to require that new buildings include vapor mitigation measures in areas where unacceptable VI is possible.

Future Investigation includes new monitoring wells and soil sampling.

Vapor Mitigation would include vapor barrier plus sub-slab venting system – costs assume 10 future residential buildings, each with a 1,600 ft2 footprint

Costs: Capital: $ 459,000 O&M (NPV, 30 years, 7%): $ 918,000 Total: $1,377,000

Note on Costs

FS costs calculated pursuant to EPA’s guidance, which requires use of 7% discount rate for net present worth analysis of long­term O&M costs.

Using current Whitehouse OMB discount rate1 of 1.1% increases O&M costs by factor of ~5.9 (i.e., an O&M cost estimated in the FS using 7% discount of $10 million would actually cost $59 million to fund using today’s interest rates)

1 http://www.whitehouse.gov/omb/circulars_a094/a94_appx-c.

Noteworthy FS Appendices Appendix B – PRG calculations

Appendices C, D & E – Soil, Groundwater and VI Cost Estimates

Appendix H – TEDE Evaluations (ResRad & Dose Compliance Calculator)

Appendix I – Institutional Controls Analysis