Operable Unit 4 - DEC Home

·:~'Afta

S024

S025

S026

S027

S028

S029

S030

S031

SS18

SS63

FT23

SSlO

Table 2-1

Former Source Areas at Operable Unit 4 Elmendorf AFB, AK

:,,.,. .r "~':';'~$, .• ".' :~~~"f-",. ,~~: 'H· .. '. ~ ~""'~::'''' .. DesOiptioii" .. t·· ! '" ; , '~~~ : ~'I .-=-. ." ,

Building 42400lHangar 10 Remains as part of OU 4

Building 42-425lHangar 11 Remains as part of OU 4

Building 43-5501Hangar 14 No Further A,ction"

Building 42-300lHangar 8 No Further Action"

Building 43-410 Remains as part of OU 4

Building 43-4501Hangar 15 Remains as part of au 4

Building 21-900 No Further Action

Building 32-060lHangar 5 Moved to Operable Unit 3

Building 22-021 No Further Action

Building 52-140 Moved to Operable Unit 7

Fire Training Area Moved to Operable Unit 4 from Operable Unit 7

Asphalt Drum Storage Area Moved to Operable Unit 4 from Operable Unit 7

'~~Oii~'~~i;' 't... . . ,.

OU 4 West

OU 4 West

OU 4 West

OU 4 West

OU 4 East

au 4 East

au 4 West

OU 4 East

"lqese source areas, while reconuneodcd for No Further Action, arc still iDl:ludcd within the boundary of au 4, and the groundwater and soii'coDiamination at these sites will be addressed.

April 1995

ELMENDORF AIR FORCE BASE, OU 4 The Proposed Plan for Remedial Action

INTRODUCTION

'fhl.' U5. Air Force (USAF), Rq::ion W ()f the U.s. Fnvirnnmental Protl~dilln Agerh:y (EPA), and the ."Jaska Department of Envmmmental Conservation I ADEC) an; requesting public comments on this Proposed Plan. It ,1ddn's:-'l'~ c1l'Olnup of contaminated soib and groundwilter at Operable Unit 4 (OU 4) of Elmendorf Alr Force Basc' (.4. FB), ()U 4 i~ an area of soil ,md gr,.lUnd\\ dter Clmtamin,ltion ddjacent to the milin rmway (see Figure 1, pdge 2).

In AU).,'1Jst l l,yO, EPA added Elmendorf AFB to the ~JatJ()nal Priuritil's List (If hazard,lUs waste sites th,l1: need to be ckaned up, On 22 f'Jovember llJY1, the liSA F, EPA, ,md ADEC si~ed tht' Federal Facility l1..greement (fFA)for Elm('ndorf AFB. Underthc' term~ .:f the agreement, all remedLll n'spon~I.' activities to protect publiL health and wdfdre and th('environment will be conducted in accordance 'vilh applicable fed-• 'fal and statl' laws.

l'his Proposl'd Plan is based on a report entitled the /":emediai illV!".;tigatiolljFea:;ibiidy Study Report for Oper~ a hie LInit 4 The Propospd Plan highlights key infonnabon fTtlm thl' remedial investigati\Jn / feasibili ty study (RlIFS) report. The RI /FS report and l.ther infonnation relai:E:'d tu this proposed cleanup are available for puhlic review in the Illfonnation R('po~itories, which ,1fe at the locations listed undef the Community Participation section of this Propospd Plan. The community is encouraged to ('omment on this Proposed Plan during the public comment perit,d, Sel' the Community Participdtion box at the bottom oj this page for more information about thE' commentpt'riod and public meeting.

Note- fhroughllllt th1s Proposed Plan, speCIal key terms arc highlIghted in hi ,Id face. italics. when they first appear. These terms appear hoth in the text and In the Glossal';. You :Lre enwuragcd to consult the Glo"ary if you 'Nould like all ,nle detailed explanation I f any "I' these ,erms.

Thp I'ropo~('d Plan has four purposes:

1. To identify the preferred aItemative(s) for remedial adion (cleanup) at OU 4 and explain the rl'asons for the preference;

2. To describe the nature and extent of contamination and the n>medial options that werE' evaluated in the RI/FS report;

3. To solicit public review of and comment un all of the al\:pmativC's described; and

4. To provide information on how tIll' public can be involv\'d in the remedy selection process,

This I'ropn:-oed Plan is part of the public participation n'qUlred under Spction 117(a) of thl' Comprehensive Environml'ntal Response, Compensation, and liability Act(CEHCLA)"commonly known as th(' "Superfund Prngram," as amended in 19R6 .

COMMUNITY PARTICIPATION

PUBLIC COMMENT PERIOD FOR OU 4:

11 April 191.)5 to 12 May 1995

PUBLIC MEETING to Discuss Remedial Action Alternatives ilnd Receive Public Comments:

Wednesday, 10 May 1995-7:()() to 1.):00 p.m.

UniVl'rsity (]f Alaska Anchorage

Busilll'ss Education Building

Room 207

I I I

I k I

~ .. ~ ...... ~ ... ~~~~~~~~~~~~~~I

Elmendorl Air Force Base

You are encouraged to provide input on all of the alternatives. Your comments can make a difference in deciding which cleanup alternative will be chosen. The USAF, EPA, and ADEC will not select a cleanup alternative until all public comments have been reviewed and considered. Changes to the preferred altern.ltive or a change from the preferred alternative to another alt('mative may be made if public comments or additional data indicate that such <l change would result in a mort' appropriate solution. The selection of a c\panup alternative will be documented with a Responsivenpss Summary in a Record of Decision (ROD).

SITE BACKGROUND

Elmendorf AFBis located approximately 2 miles north of dnwntown Anchorage, Alaska (see Figure 1). [t is bordered t() the north and west by Knik Arm, to the east by Fort Richardson Army Post, and to the south by a light industrial arm and land owned by the Alaska Railroad Company. Elmendorf AFB was opened in 1940 and provides defenscfor thl U ni ted States through surveillance, logistics, and communications support. OU -t is locltE'd in the central p(lrtion of the Basc, imd inclllde~ m, )stof the area around Hangars 8, 10, 11,14, and 15, as well as thE' fonner fin' training area (FT A) and the Asphalt Dnlm Stordgl' Arpa (A DSA).

OU 4 is o;itU.ltcd on rdativdy fla: tl'rram CIt Cln approximatt· elevation of 195 feet ~bovc mean ~ea level that slopl!s gradual1y to the :"outhvvest. Crnundwater is di vided into an uppn <lnd a lower aquifer by· an impermeable layerof silts and (tlys called the Bootlegger (:ove Fprmation. The ~Oll ab..lve the dividing layer is made of sandy and gravelly sediments that Clllow groundwatc'r to flow. Water frllm thIS aquifer is not med for drinking water in the Base area. Water in the upp('r aquiler flows to the -south and w('st across OU 4. This Clquif('r is influenced by the presence of the Elm('ndorf MorCline, which Clets ,lS a groundwater bClrrier 10 the north, and by Ship Crl'ek, which is the point of dischargt' for the majority of upper aquifer flow to the ~outh. "Tne lowl'r aquifer i" a backup sourCl' of water for base residl'nb, industrial purposes, cooling wClter for the power plant and fish production at thl' fish hatchL'rv.

TJw USAF identifil'd several potential sources of groundwater and soil contamination at OU 4. Contaminants include jet fuel, gasoline, diesel fuel, kerosene, trichluroethylene (TeE, a solvent), BTEX (ben-

2

au 4 Proposed Plan

--------,

-)

Figure I. Location Map Of Elmendorf AFB, Alaska

zene, toluene, ethylbenzene, and xylenes--volatile compounds from fuels), and asphalt. Sources of these materiab were leaking underground fuel storage tanks and related valves and pipes, fuels and solvents used in fire-fighting training, drums of asphalt stored on the gruund, and floor drains from hangars. Releases of these contaminants, which occurred between the ICltc 1 Y50:-, and the late 1980s, were investigated by the LISAF.

There are four principal buildings located within the western part of OU 4 that were former source areas: HClngars 11,10,11, and 14. The FT A also is located in the western part of OU 4. In the eastern part of OU 4, there are two f( lrmer source areas: the ADSA and Hangar 15 neClT Bu i1d ing 43-410. All seven forml'r source areas are being consideTl'd for cleanup. (See Figure 2, page 3.)

Thl' hangars were defined as former source areas because each contained floor drains through which hazardous materials were believed to hClve been re-

(

au 4 Proposed Plan

' . . -."!'9C ,:'! !J.Fi.<:,U!~J! ~.I· '<'F,llly LJI

~ cncrl98

Figure 2. OU 4 Study Areas

leased into the subsurface via drv wells and/or leach fields. The FTA was identified a~ ,{ former source area became of fire training ilctivities mnducted there. The ADSA was identified as a f()rmer source area because asphalt had I'ither leaked or spilled from the storage drums.

As a n~sult of their recent inwstig.1tion:". the USAF has repaired or TI'moved all known s()urce~ of contamination at au 4, and access to ,'ontaminated areas is now controlled. In the last few years, the LJSAF has perlormed such work as the remov.ll t)f the old asphalt drums and revegetation of that ared, thl' deactivation of the FT A, the testing and repdir of ,Ill piping and tanks at at 4, and the rerouting of au 4 hangar drainage.

NATURE AND EXTENT OF CONT AM INA TION

Contamination at au 4 was found in bothsltallowand deep soils and in ground water. The sources and types of contamination and the extent to which the soils and groundwater have been affc'Cted are di~cussed below,

3

Elmendorf Air Force Base

Contaminants

Soils. Soil contamination at OU 4 was detected in samples of both deep soils (> 5 feet) and shallow soils « 5 feet). Gasoline, diesel, jet fuel, BTEX, and other fud-related contaminants are present in the soils at concentrations exceeding cleanup standards at the area.;, mmprisingOU 4. Polychlorinated biphenyls (PCBs) also were detected at very low concentrations in soils at Isolated locanons, but were well below cleanup standards and acceptable risk. Low levels of heavyend contaminants, such as asphalt and tar by-products, wen' also commonly found in the au 4 soils, The maXImum concentrations of chemicals detected in soils that exceed standards are shown in Table 1, page 4,

As phalt-ty pe contaminants were found a t low levels at each of the au 4 source areas in shallow soil samples. These contaminants were detected in isolated occurrences that were generally below the acceptable risk ranges. Since these types of contaminants are relatively immobile, they do not tend to percolate into the groundwater. If a hypothetical resident eats the contaminated soil, there would be a risk.

In the dt'ep soils, the primary contaminants detected wen' fuels (dieseL jet fuel, etc.). These contaminants, although posing no current risk since they are buried, can percol.lte into the groundwater and may contributt' to groundwater contamination some time in the future. Because low levels of fuels were relatively widespread in the deep soils at the FTA at depths of up to 40 feet (about 10 feet above the top of the ground water), some dction may be required to remove the fuels at thIS loe ation for protection of the groundwater. Relatively high levels of fuels were detected in the deep soib at one location at the ADSA and at two locations at Hangar 10/11. This contamination was detected at depths of about 25 feet above the groundwater table. Because of the high levels of fuels detected, some action may also be n'quired at these locations tll protect the groundwater from future contaminatioll. No other fuels contamination in the deep soils at au 4 poses a significant risk to groundwater.

Groundwater. The groundwater screening program idl'ntified several contaminant plumes in the upper aquifer at the suurce areas. The plumes are totally contained on base property and do not currently affect any groundwater users. The organic contaminants of concern exceeding standards in groundwater include fuels, BTEX constituents, and chlorinated solvents. No


groundwater plump was identified in the ADSA area. The maximum concentrations of chemicals detected in ground water tha t exceed standards are shown in Table 2, page 5.

Five areas of groundwater contamination, or plumes, were identified atOU 4. Oneplumeof fuel-related and solvent contamination was detected moving to the southwest (in the direction of groundwater flow) frum the FTA.111is plume extends to the westof Hangar 14. Prohable o;llUrC'es of the plume have been addressed through actions that include the testing/repair of a large undprground fuel tank and lim~s near the FT A, and the termination of fire training activities.

A sl'cond, ~mall plume was dl·tected moving to the southwest with groundwater now from Hangar 11 Onlv one of four wells indicated contamination. Relativeiy high levels of fuel-related contamination were detected in this plume, which originates from a valve pit to the west of the hangar. Again, action has been taken to address the source, V\ hich mcludes the decommissioning of the valve pits in 1993 and the removal-s('lil'duled for 1495---1,f tlm'e underground storage tanks that were served by the valve pits. These tanks were investigated as part of the State-Elmendorf Envlronmpntal Restoration Agreement and were determined t(, be leaking_

A third fuel-related plum(~, corning fwm Pump HOUSl'

2, was detected near Hangar 10. To address the source of this plump, the pump housl' has been tested and repairs made as needed. An effort has also been made

OU 4 Proposed Plan

to address the sources of contamination at the remaining two plumes at OU 4.ln both of these plumes, the levelsof contamination detected were lower than those at the other plumes found.

A groundwater model that predicts the migration of contaminants in the groundwater has been developed tor Elmendorf AFB. The model considers the types of soils, the direction and rate of movement of groundwater beneath OU 4, and the type and amount of !-,'Toundwater contamination. The model shows that benzene and TCE {indicator contaminants) in the OU 4 area will migrate approximately 1000 feet over the next 15 years, generally to the south-southwest. The areas of contamination are predi cted to broaden for the next 10 years, and the concentrations of contaminants will diminish. The model shows that within 15 years they will have decayed and dissipated to below acceptable cleanup levels, assuming that no additional leaks or spills (1CCur.

To suppurt these modeling results further, Elmendorf conducted a detailed study of the natural processes uccurring today in the groundwater at OU 4. The purpose of this study was to look more closely at the activity pf microorganisms feeding on the contaminants, and other natural processes that remove contaminants from the groundwater atOU 4. AftercolleC'tingand t'valuatingOU 4 soil and groundwater samples, the study confirmed that contaminants would be reduced W below cleanup levels long before they would re,lCh other parts of the Base or Ship Creek.

~.--------------------------------------------------------------------------------,

f--------Table 1. Soils Contamination (Shallow and Deep)IACM" Standards (Level D)

Maximum Concentration (mglkg)t

Source Area

ITA

Contaminants of Concern

Kerosene Cas(,line

HaJ-lg-ar ](),'-1-1--------- - --- Casp':":ji':":n,,::"" ------t-

Diesd

Shallow Deep

2200 I N/ A

N/A -+--_3_7~10~ ______ +-_ N/ A I 4100

Standard (mglkg)

2000 1000 -1000 2000 N/A 1 5900

Keru-;ene N/ A _---'6:::2:.:::0 ____ -1-____ -'--''--''-__ --1 f------~--- ------- ---- - ------- ---------

ADSA I Dies,-j \1O,()(l0 I N/ A

100

Jet Fuel 21 DO 13,000 Xylene:, N/ A 1 110

f--------- _______ ~ ___ C-asoli::n:..:.:c=_' ____ ...L, __ N/ A i 15,600

• ACM = Alaska Cleanup Matrix fur non underground storage tank contaminiltcd soil. tmg/kg = milligrams of contaminant per kilogram of soil; equals parh per million_ N/ A = Not above standard NlJtL~Soilluntaminatilln ilt Hangilrs R, 14, ilnd 15/B1dg 43-41 0 Wil~ not above ACM standards.

4

I 2000 2000

I 100 !

\000

"'. ,

OU 4 Proposed Plan

The findings of both the modeling work and the biological study conducted on the groundwater at au 4 indicate that contaminants should not migrate beyond the flightline area of Elmendorf AFB, and that through the na tural processes already occurring in the groundwater, contamination will be below acceptable levels in a reasonable amount of time (15 years). These findings are supported by the fact that even though the s,)urces of the';e pI umes md y have former I y been acti ve for several years (especially at the FT A), the plumes have still not migrated very far from their sources.

SUMMARY OF SITE RISKS

Analytical re"ults from soil and groundwater samples were compared with cleanup standards to identify possible contaminants of concern (contaminant levels exceeding standards). A hllman healt11 risk assessment was th('n performed to set' if there were any potential negiltive human health effects from the contamination. An ecological risk assessment was used to estimate the effects of contamindnts (In plants and


animals. On the basis of the risk assessments and cl ean u p standards, areas reqUiring remedia tion to protect human health and the environment were identified. Thestandardsand risk assessments are discussed below.

Human Health Risk Assessment

Two important measures are used in human health risk assessments: excess cancer risk and hazard index (HI). The cancer risk level is the additional chance that an individual exposed to site contamination for a long period (30 years) will develop cancer over the course of a lifetime. It is expressed as a probability such as 1 X 1a<' (one in one million). Typically EP A regards the threshold for action when risks exceed the range of 1 X 1 Q-4 to 1 X 10-<' (betwcen one in tcn thousand to one in one milli( m). The HI estimates the likelihood that exposure to the contamination will cause some negative health CHl'ct other than cancer. An HI score above 1 indicates that some people exposed to the contamination may experience at least one negative health effect.

Table 2. Groundwater ContaminationISDWA." Standards f--.

Contaminants Maximum Standard Source Area of Concern Concentration (llgiUt (llglL)

FTA 1, 1, 1-Trichloroethane 242 200 , ],1- Dichloroethene 13.7 7

i 1,2· Dichloroethane 12.1 5 Tetrachloroethene 40.5 5 TCE 74.7 5 1,2, Dichlt )roethene 741 70

I Benzene 19H 5 --- ----.--- ,--------- C--'

Hangar 14 i Benzpne 207 5 --------- f------Hangar 11 I Benzene 26m 5

I

I

E th v I benzene 1360 700 Toluene 5590 WOO ----- '-----1----

266 5 Hangar H/](l ! Benzene I '-------l---- -------- - -------,

Hangar 15 Tetrachlorol'thene 19.5 5 , TCE 23 5 _____ , ___ J ____________ ----

'SDWA = Safe Drinking Wilter Act i'llg/L = mien 'grams of Cllntaminant per liter llf water; equals parb per billion,

5

EfmendorfAir Force Base au 4 Proposed Plan

ThE' human he'alth risk assessmE'nt considered current Cl nd future fl'~idents, workers, and visitors as possible l'xp(l~cd popl1lations. Pl'llple ClJuld pokntially come into contact with the contaminants thwugh showering, skin contact, inge~ting (eating) du~t or soil, and drinkillg gf(l\mdwater. 1l1l' highl'st soil risk is from incicielltalmw'stinn ofshallo\\ soils k 5 teet) by hypo-

thetical residents, and the highest watE'r risks arc from showering with and drinking water from the mntaminat['d <lquifer by hypothetical residents. These higher estimated risks could occur only if land use were to hecome residential in the future and if the groundwater were to be drawn as a source of drinking water. Thi~ scenann represents the most romervativ{' rhigh-

Tall/e3. Humall Healtlz Risks

-------------Soil Risk" -------

I

i

Source Area

Slwllow S i{,'sidl'llti,li

(RMF)'

Deep

CUrrl'llt Con-tn]ch( In o( cnpatll In']i' W'lrkcr'

I -I

I

! ChemicaI(s) Driving the Risk - ----

nd, « 5 1<,,,t) + Snd, (> Sf""

------~---- ---~--~ -+--~

2.7 X W FTA

+.1 X 'tr

Hangar 14 2.S X I()-'

Hangar 1(1/ II

< 10 ' < 11~' I Fud~ and fuel resjuul'~ I . -L _ ~ __ ~ __ ~~

--~ ---_._._----

r---~·--<: Hr' < 111'" -1-FU('IS and fuel residue~ -~.~~-~--.~-~ -r- - .. - ~---- . ~---~----~--- --------

15X1W < 1{~' I Fuels and fuel residu{'~

Hangar II :l.S XW .~-.--- --'- - -- -- ---- ·tF~~~is and fuel resid-;:I~~-' 1.2 X Ill" < 11)'

!

Hang;u 15 "t- --~----

2.1 X 0" - -- .+-- -_.- ._- --+-=~- ... ----~--

<10-' < 11 r" : Fupls and fuel residup" :

- -- - ---------t--- - _._"- ---- --+ \DSA 1.2 XU < Hr' <1(\' Fuels and fuel rcsidU(',.

.- ------- -'--- --- - ---- ~. ---------

Groundwater T\ isk' .~

I Rl'Sldl'lltlal (R1\1 --~-.. ~'--'-~ ..... ~ .. -~ -~-~- --~

E)i< i f'uturo' 0. 'Cup.lti( -n"I' ~- -~'~-r--~'~"

-------- --;---~~--~-- ----------

FTA 2.IX'()';Hf

Hangar 14 2.1) X Itt'; HI

Hangar 11 L) X ]()-; HI

Hang<lT H/1O Y.7 X j()-

I-Iang<lr 15 15 X i ().

= 2.X I 15'\ 11l-'; HI , < 1 ! Benzene, ethylbenzl'lw, tolul'ne,

- -----t------- -.--~~---.~ sn]vl'nb -

~ ~

I

= 1.:\ I 1.2 X 11 l"'; HI = < 1 I Benzene - --~----~- ~---~ = 9.1 i 2.0 X 1Il-1

; HI = < 1 Benzl'ne, toluene, ethvlhenz£'lll' r- ------ I - -

\Benzene 'i.X '< 111' ----- ---- - --------

< llr' TeE, chloroform, chloromethilm'

---t---<.IW -------- -----t~--

__ L ___ ~~_~_ ~)t applicable

"H"ks are (<Ill ulatl'd by thing till' Y::;':: UPPl'! ,i cun~l'rvativll C'-.;tinlate uf tbe !lv\'f..)r~t ca..,c" (

hE XCl'", Canl'l'T nsk, C(ln'il'rv.ltively as'.uml-d j'ltUTl' rl'sidenh (Rl-a~ondbk MaxirTll:m Exf'

'F XCl", cam er l'hks cons('r\'iltiv('ly ih-lll11Pd dE XU'SS C,ln,'cr n,k, c()n'l'T\'ilti\'eiy ih',uTT1C'd 'F XCL'," ,:an( er ri,J., - con'ln',1ti\'L'ly ii" LImL'd cl'nditil'ns (..:lrillking gWtltldWdtl'T, etc .),

'confidence limih (LJt 'I'i) fllT contCirnin<1nh pre-;ent, The 95% UCL., rl'prl'Sent 'ont<1mill<1tioll, for :)11 Yl'ar, of l'XPllStlT!- (drinking grtltll1d w<lter, Clllltact with soii, ('te) by , )SLlre), fnr 25 Yl'ar, of l'XP"'UTl' whill' wllrking Ull ,itl' LInder current c[)nditi"n~, for 1 year of CXPll'UTt' during lm-sik clm,tructilln Wllfk (digging, etc.),

for 25 Yl-<lrS elf expc Iq!T(' whili' workIng Ull ,ite under hypothl'tical future

HI =, Hillard Index (il ml""LIJ'C ,)f l1011,'arc-inl' genic risk),

IW'--

au 4 Proposed Plan

est exposure) sct of assumptIons used in the risk assc~sment and is known as the Reasonable Maximum Exposure (RME). If land use is restricted in the future so that no drinking water well~ can be installed in the shallow aquifer (as currently exists), the water in this aquifer would continue to pose no risk to human health or the environment. Levebofcontamination in deep soils (> 5 feet) pose no human health risks.

Thl' area~ where the eXCl'SS cancer risks exceeded 1 X 1O-e (one in one nullion) or thl' HI was above I for several of the risk scenanos dis,~ussed above are listed in Table J, below.

Ecological Risk Assessment

An ecological risk assessment was conducterl to assess which plants or animills may be exposed to contaminants and the likely effectc; of that exposure. AI1Imals may be exposed to contaminants by eating contaminated plants, animals, and soil; coming into contact with the contamination; and lif they burrow) breathing soil vapor5. Plants are exposed t~ contamination through thc' soil or water. Plant and animal eff('cts wc're considered in thl' ecological risk assessment.

Th(~ remedial investigation did nut identify significant ecological impacts warranting action. Potential impacts on f!'presentative wildlife (moose and meadow voles) comuming planb grown in contaminated soil were calculated, but no significant impacts were detennined to be pre"ent.

SCOPE AND ROLE OF RESPONSE ACTION

The au 4 remedial investigation identified groundwater and soil contamination-primarily fuels and sol vents. To remeJiate (clean up) the groundwater and soil clllltamination most effectively, the preferred treatment al temati ves will target both shallow soib and deep ~()ils. The response altion, or method used to remediatl' the contamination at au 4 is part of a ba~ewide effort to clean up contaminated media.

7


The response action addresses impacts to human health and the environment through the following:

• Protecting human health and the environment by reducing cancer and noncancer health risks to within established health guidelines;

• MePling the state and federal environmental laws and regulations for the specific contaminants, actions, and locations;

• Selecting remedial alternatIves that include treatment to the greatest extent practicable; and

• Selecting remedial alternatives that are cost effective and consistent with other OUs at Elmendorf AFB.

SUMMARY OF ALTERNATIVES

T(l clean up the contaminated groundwater and soils at au 4, a wide range of possible alternatives was t:onsidered, In general, there are many potential options available to remediate groundwater and soils. The fiw most promising options were chosen on the basis of effectiveness, implementabihty, and cost. To treat groundwater, the analysi~ considered four alternatives; for soil (both shallow and deep), five alternatives Wl're considered. Each alterna ti ve is discussed on the folluwing pages. A "G" repre~ents an alternative (:onsidcred for groundwater, and an "S" represents an alternative considered for soils.

Alternatives Gl and 51: No Action (Groulldwater and Soils)

Alternatives G2 and 52: Institutional Controls with intrinsic Remediation (Gruulldwuter and Soils)

Alternatives G3 and 53: G3 [n Place Air Sparging (Groundwater) S3 Excavation and Recycling (Soils)

Alternatives G4 and 54: G4 In Place Bioremediation (Groundwater) 54 Excavation, Biopile, Backfill (Soils)

Alternative S5: S5 [n Place Bioventing (Soils)

"' .. ,-"""~-,-, ... , ... ,,, .. -, -'--"'" -,,-.,-------.-----.-~----------------------


Alternatives for Treating Contaminated Areas Throughout OU 4

Th.~ five aItcm,ltiVl's are described helow TI1e cost of Al ternative~ 2-'1 includes up to J() p'afs of monitoring

gn.undwah·f and/of soib fOf the contdminants of cOllcern Thl' m,mitoring a~sumpti()n for each aitemati\'(~is based on t i1l'l'stim.ltl'J time (in Yl'ar,,) to clean up gn ,undwatl'f ,md / or ~c lib tll <lcn'ptable levels. The actual monitoring pwgr.un will be devdclped as pilrt of tht' dc,ign (1f the ~electL'd .lltemati yes. The co"ts and tiere of c1mnup f()r l'ach (1f thc' altl:'rnative~ are shown in d tilhl.' hefort'l'ach illlL'rniltJvl' b dc,cribcd.

Alternative G1 No Action ((;rolilItiwc1ter ) Alternative S1 No Action (Soils)

Ev;,luiltiol1 of tIll' no ill-tilln altern,ltive is required under CERCLA ilS a bast'line reflecting current conditiClTIS without allY cleanup. ThJ~ alterI1dtivl' is used for cOl11pari';on with each pf tIll' other altenlatiVl's, but dO( s not includL' ilny long-tc'rm monitoring, contrub, or ,ICCl'S, restridions. Tlwn' .In' nil ({ lst~ associ" leu witI-] thi~ illtc~rndlivl'.

Alternative G2 Institutional Contruls with Intrinsic Remediation (Groundwr1tcr)

_ ~ Alternative S2 Institutional Controls ~ with Intrinsic Remediation (Soils)

[-----I

! SourCl' Arm

,FTA

Hangar H , Hangar 10 /11

Him)!.a] 14 - -

Hangilf 15.

I,<\D~A ____

OU 4 Proposed Plan

,----------------

I ! I I l

52 Costs (Thousands of $) Time to

i Pn.'sl'nt Clmnup

Capital Annu"l Wurth (year.,) -+--"-----]

20 y 7h S

4 12 4 ----H

__ 4_

1:;

3 -.1-. b

3~=~r 3 I - ----1'-il

lil 27 12

14 61

11 2 4

!I Cmunuwail'r and soil would be fl'ml'diatl'd by natural prucesse~ (physical, chemical, and biological) that n'dul't' contilminant concentrations. Roth the mudding n'sults and thl' bi()logical stud Y CClnducted at OU 4 confirm that intrinsic remediation would dean up thl' cont<lminilted mediil to below ilCCl'ptilhk levl'ls in a rmson,1bleamountof time. While intrinsic fpmediation is wori-.ing, land use restrictions would be used to limi t access to contaminated groundwater and soil. These would prohihitconstructionof residl'ncL'sand groundwilter wells (lver areas with contaminant plumes and prohibit excaviltion of soil in areas of soil contilminiltion thalexcL'L'd acceptabk levels. TIl(! Air Force would continlle to munitor groundwater and soil quality for the duration of this illternative. If there is any indication thilt intrinsic remediation is not ,lChieving tht' cll'anup level" within expected timeframt.'S, the remlL

dial actions will be reevaluated and Cldditional action will bl' t"ken if nE'cl'ssary.

Alternative (;3 [n Place Air Sparging (Groundwater)

1""

r

au 4 Proposed Plan

In Alternative G3, air sparging wdls would be installed in the area of contaminatLu groundwater. Air would be injected into the wells and be sparged (blown) into the groundwater below the water table. As the air passes through the contilminatl'd groundwater, the l"mtaminant~ of concern would be ~tfipped from the water phase into the gas phase, Inaddition, someofthe oxygen would dissolve into the gnlundwater, creating an aerobic en\'ironment that would enhance biodegradation of ~()ml' of the Tl'maining contaminilnts, Some of the mntaminants could migrat(' to the land ~urfac{' a nd be emitted to the atmosphere. This alternativeal50 would rely on land use rC'"triction~ and the monitoring program de'cribt'd in Altl'mative C2,

Alternative 53 Excavation and Recycling (Soil)

r" ----- :~-s~~~FC~'~lsal~i~~:,~~ ;ri:~:~:l(~l f"source,A,rea_. Capital ~.".!~I~~~ ~('rt,h_i-Jymr:.'.~' FIA" "" _ _lS7h_, O,iS7h_l_ 1 Ha ngar 8 136 (l 136 I I , H-angarl"O/11 314 0 '14 I i

f!,anlSilr 14\07 () ,07 II 1 I

:~?~~~i __ ~~: __ ~~ ___ ~;! ["~~_J Altern;ltivL'SJ mnsists of l'xcilvatlng the nmtaminated shallmv snib ,md tran:-pnrting tJll'm to ;; comml'rciCiI Tl'cycling facility in thl' Anchorage area Excavations \\ ould be backfilled with clmn soil. At thl' recycling facility, thl' contaminated soils typiCll1y an' treated in a low-temperaturv thermal trmtml'nt unit designed to f['m()vl' volCltiil' contilmin;mts fn lITl tIll' SI )it The ~oil is then r(,cycled for road base or othl'r projects. ll1is alterniltive W,l" developed for shallow soils (14,l)C~1 J(j3) only, bl'c.msl' l'xC<lVilting all contilminatl'd deep scdb (21 ),4(~) yd ') would not lx, Cl cost-dfl'CtiVl' Of tl'chnil<llly fpasibk ,dtenlCltiH'.

I)


Alternative G4 In Place Bioremediation (Groundwater)

In thi~ alternative, a series of wells w(Jllld be installed to extract contilminilted groundwater. Extracted grnundwall'r would be piped above ground to a mixing tank, wlwre the pH is Cldjustt'd and oxygen and nutrients ill"l' addl'd, The groundwatl'r wlluld then be reinjected into the aquifer through injection wells to hi[)dl'gradt' dissolved contaminants in place, When l'ompared with other contaminanh, the principal contaminants ilt Hangar 15/Building 4:1-410 and part of thl' FT A an' more resistant to biorl'ml'diation. Therefon', Altprncltive C4 would not be as effective at treating the groundwater at these two sites. ll1isilltenlativl' (lb(l would rely on land use rE'strictions and the monitoring program ,kscribed in Altem<ltivl' G2,

AlternativE:.' S4 Excavation, Biopile, Backfill (Soils)

Elmendorf AIr Force Base

Altl'rn<ltiVl' S4 Clmsisb of l'xcilvilting contaminatl'd shilllow ~oib, trilnSpllrting them to an ol1-b<lsl' biopill' cell, b-c(lting the soils until (lccepta bIt, Il'vd~ an' fl'ilchl'd, (lnd hilckfill mg tht; l 'Xl',\V,ltlOn- with trl'atcd soil or otlwr clciln borrow m<ltl'ri,tl fnm-\I)Il ha-['. At thl' biopile cell, s )i1s wnllld be mounded OVC'f a -('rips of pc'rfma ted pipc~ lll1 topllfrm impl'rmeable IirH~r Airdrclwn through thl'l)Vcrlvinf', pile would enhanct' il['mhic ckgradation of orgilnic ('(lntilminilnt~ ill\cl strip the {oliltilc orgilnil compound" iVOCS) fmm the s(lils Soil from the pile wou]j he '" mplc'd pt'ri(Jdicilil y to determil1l' tIll' prugTl'SS llf the remediati'll1. One(' thl' S( ,il i-; cl('an, itcm bc' us,'d f'lT hcKkfill on h,)s'"

Alternative "5 [n Place Bioventing (Soils'

---- --- - I S~ C~ ,~t~ 01~)u'oI-11~i, -,;{-\) r---- -- - ---- l;-;'c",-;:;t

I Sl ~l!~l' A~'a ~~<l£~'" ___ An.r:ual __ Iylll 10_

FT .\ q(j 1h 17 \

I

IH<)ng')TR NA NA N,\ Hang,ITl!lj;1 41 Ii' 7,

l~ang,)r14 I NA. '\14 Nil IHdng'lrl~ t 42 11 ::;1 I A.DS,t\ '41 27 l),J

: "J;\ c, '>.J(\t appllcahl,',

Timet" Clmnup

~ypar'L_

2 NA 2 NA

2

----- -- -- -- --~------ - --- -.~ ~~-------'

10

OU 4 Proposed Plan

In bioventing, air is injected into tlH' soils to incrpasl' the oxygen content. By increasing the oxygen content of the soil gilS, bioventing increases aerobic degradati(ln of the contaminants by natur<llly occurring microorgc1nism~. Unlike Altematives 5] and 54, this altemative WilS developed to ilddress only dl'ep soil mntilminiltinn. Bioventing is considered highly effective for deep soil contamination. [n addition, Alternative 5S callo.; for the land use restrictions and soil monitoring dcsl'ribed in Alternative 52.

EVALUATION OF ALTERNATIVES AND PREFERRED ALTERNATIVES

The preferred alternatives for au 4 were sl'lected on the hasis (If ninp remedial alternative evaluil bon criteri;1 found in the National Contingency Plall. Tilble 4, page' 11, identifies ilnd defiI1f's thl'~e criteria_ A detaikd comp;m1tive analysis of all of the alternatives wlth resp!'ct to th('se nine criteriil i~ presented below_ 1l1l' ninealtematives considersi tc-sppcific factors such a" the exbting site risk and levels of Cllntamination, as wdl ilS nmrc dlternative-specific factors such as an illternath (,,~ long-term cffectivL'ncs~ and implcnll'n tahili tv.

C( lJ1 tamin.ltion ,1 t OU 4 falls into thre(, bil~ic catl'gories:

•

•

Ground wilter; Shallllw soils; ilnd Dl'ep "lib_

The prderred a I tl'rnative for groundwa ter il t illl source ,m'il:, is Altl'miltive G2 (institutional controls with intrinsic Tl'mediation). Altemativl' 52 (instituti()nal controls ,"lth intrinsic remediation) is also the prptl'rn'd aJt!'mativl' for shallow soils at ClII the source an'a", and for the deep soils at Hangar 15. Altemative 55 (],ioventing) i~ the prefl'rred altern,lti ve fur the dl'ep soib ilt the FTA, A D5A, and Hangar 11. Altematiw 55 was chosen because these three areas could act as a futlJrl' SlllHc{' of groundwilter contamination and thus pose a human health and environmental risk. The preferred illtl'rnativl's ilrE' summilrizl'd in TableS on pilge 12 hgure.l, p,'ge 13, provides iln illustriltion of the pri'fl'rred ,] Itl'rniltives. The over(lll pre5cnt worth cost ()f these pn.fl'rrL'd alternatives is $lJ6H,()()().

...--

au 4 Proposed Plan

Comparative Analysis of Alternatives

The basis for comparing the alternati ves is their ability to meet the criteria inc1eaning up the areas that require remediation. The discus~ion below compares how each of the five alterna tives meets the nine Na tiona1 Contingency Plan criteria.

Protection of Human Healt1l and the Environment. For groundwater, Alternative G3 (air ~parging) would provide the ~reatest protection of human health and the environment because groundwater would be acti vely treated to acceptable levels. Contaminants would be stripped from the groundwater. Alternative G4 (in place bioremcdiation) is slightly less protective be'.:ause It may not be effective for treating the solvents


that are present atthe FT A and Hangar 15. Alternative G2 (institutional controls with intrinsic remediation) is slightly less protective than Alternative G3. Alternative G1 (no action) is the least protective, since there would be no institutional controls and no monitoring, so that future contact with ground water contaminants would still be possible.

For shallow soils, Alternatives S3 (excavation and recycling) ilnd 54 (excavation and biopiIing) would equally provide the greatest protection of human health and the environment. In both cases, contaminated soils would be removed (thereby eliminating risks), but some contaminants would be released to the atmosphere during excavation. Alternative 52 (institutional controls with intrinsic remediation) would also be

r------------------.--------------------------------------------------------------~

Table 4. Remedial Alternative Evaluation Criteria

Evaluation Criterion Definition

Protection of human health ,md I Protection of both human health and the environment through the elimination, the environment. I reduction, or control of contaminated media. ---- ----- --------- -- --- L-- ----------------- ---------------.------1

Compliance with ARARs. II Complies with applicable or relevant and appropriate requirements (ARARs) such as laws and government regulation".

I .-.---------i=---.-------------------------. Long-term effectiveness and I[ Protection of human health and the •. 'nvironment after the remedial objectives permanence. have been met, including adequacy .md reliability of controls.

Red~ctio~i-Il-toxicity, ~&'i11ty, -I":i~atment to red~c~thl'~oxic~~, m~l~ility, and / or volume of the contaminated or volume through treatment. L media.

Short~~~~-l:ffcctiVt'~~s~.- ---I Pr~t~ctio;of h~~~~heaIth ~md-;h~ environment during o:nstruction and implementation. Deb'l"ee of thrmt and the time period to achieve remedial action

i objectives are also considered.

,lmPiemE'~;bili~.--- - --- t-The availability ~f-~aterials a~d per"onnel, site features such as available space I and topography, and impacts upon ongoIng operations are consldercd. Thc I technical status of aiternatlvl's is alsll considered; theoretical technolOgies with

~()nl v hrni ted bench-~cale ev.lluation are Cllnsidered less Impil'mentable than fully proven proce~~es.

,------- ---- --- - ---------------------------- --------/

Cost. ; Co:·.ts include design, constnlct1on, startup, monitoring, and maintcnance; i Aouracy to within --3D'/' and +5D';7,_

;- State acc;~ance-', --------I Indicates whether, on thebasi~ofits;(:'-'-v-i--e-w--l-)f-t-h-e-P-r-o-p-o-se-d-P-lanand supporting

do( uments, the State concurs with, opposes, or has no comment on the preferred I altl'rnativc.

;------------------1-· - --- ----------------------1

: Community acceptance I Thl' community'S preferences will bt· assessed in the Record of Decision followi ing a review of public ClJmments recl'ived on the Proposed Plan and supporting [ documents.

-----------------------~.--------------------------------------------------------~

11


protecti ve of human heal th, using land use restrictions to prohibit contact with or ingestion of the contaminated shallow soils. Alternative 51 (no action) is the least protecti ve, since there would be unre~tricted access to contaminated soils.

For deep soils, Alternative S5 (bioventing) would provide the greatest protection of human health and the environment because contaminants would be broken down in place, thereby eliminating risks. Some contaminants would be released to the atmosphere. With Alternative 52, land use restTictiom; would prohibit excavation of contaminated soil, mjnimizing the risk to human:; or the environment. Alternative 51 is the least protective, since there would be no restrictions on excavation of contaminated soil.

Compliance with ARARs. For groundwater, Alternatives G3 and G4 will be aggressive treatment and will comply with cleanupstandard~. AItemativeG2 would also comply with applicable cleanup standards, only the time tn achieve these levels would be increased. Alternative Gl would fail to meet the requirements, since then' would be no way to confi nn any reduction in contamjnant levels.

For shallow soils, Alternatives S3 and 54 would have the highest probability of complying with all requirements. Alternative 52 would meet the standards over time. Alternative 51 would fail to meet the requirements, since there would be no way to confirm any reduction in contaminant levels.

au 4 Proposed Plan

For deep soils, Alternative 55, as an active treatment, will comply with all reqUirements . Alternative 52 would meet the standards over time, except possibl y for some hydrocarbons at the ADSA or solvents at the Ff A. Alternative Sl would fail to meet the requirements, since there would be no way to confirm any red uction in contamjnant levels.

Long-Term Effectiveness and Permanence. For groundwater, Alternatives G3 and G4, as aggressive treatments, would reduce risks by eliminating contamination. Alternative G2 would reduce contamination permanently, but over a longer period of time, therefore requiring additional long-term management. Alternative G1 would not prohibit future groundwater contact, and there would be no long-term management.

Elr shallow soils, Alternatives S3 and 54 would reduce risks by removing contaminated soil and breaking duwn Clilltaminants. No long-term management would be needed after the contaminated soils are removed. Al terna ti ve 52 would reduce risks by prohibi ling contact or mgestion of the contaminated medium, but would require long-term management (land use restrictions, five-year review, etc.). Alternative Sl would not decrease risks and there would be no long-term management.

Table 5. Preferred Alternatives for au 4

Soils -

Source Area Groundwater (plumes) Shallow Deep f------

ITA G2-IClR* 52-IClR 55-Bioventing f------ --- .-- -- ---

Hangars X/10 (plumes only) I C2-IClR Not applicable Not applicable Hangar X (soils only) , Not applicable I S2 lClR Not applicable ~--- --j---

Hangar 11 (plumes only) C2-IClR I Not applicable Not applicable Hangars 1 Dill (soils only) i Not applicable 55-Bioventing 55-Bioventing I--.---.------~-- f-.--.

! S2-ICIR Hangar 14 , G2-ICIR Not applicable

~.------------t--- f-.---

Hangar 15 G2-IClR S2-ICIR 52-IClR 1----- I .----------1---

AD5A Not applicable 52-ICIR 55-Bioventing '-'---' --- '---_.

*IClR = Institutional controls with intrinsic remediation.

12

· - -_._-- -_._---_._, - --_._- --'.'--_._----

au 4 Proposed Plan Elmendorf A;r Force Base

WEST EAST

Bioventing Institutional Controls

Bioventing

Monitoring and Intrinsic Remediation lor Groundwater and

~~ ~ Monitoring and Intrinsic Remediation for Groundwater and

Figllre 3, Preferred Altematives

For deep soil", Alt('rnativl' S5 would reduce the rish through treatmpnt. No Illng-tl'rm management would heneeded. Alternative 52 would reducni~ks through l.md use restrictions and long-term mimagement. AI-ternative Sl would not decrease ri,k~ and there would be no long-tl'rm managl'ml'nt.

N.eduction in Toxicity, lHobility. or Volume Through Treatment. Ft1r ground\\i<lter, Alternatives G4 ilnd C3 vvould provide the greatest reductilln thnmgh treatment. Alterndtivl' C2 w()ldd provldl' reduction in toxl:ity cll1d vohlml'; howevl'r, the timl' to (lchieve the reduction i~ Il1Ilgl'r (lnd this altl'rnativ(' does not in\ (JIve treatml'nt. Mnhllit\, would not be reduced. AIkrnative G1 provide5 no trC'(ltml'nt and no monitor-1'1g,:oO any dtl'Cti ve T£'dudion could not be evaluat!'d,

For shcl1low ~Ilib, Altl'rnatiVl's S3 and ")4 would pm\ idl' equal contaminant reduction through excavation .md treatment. With Alternativ(' S2, thl' toxicity and \ olume of contaminants w01lld hI' reduced through l11tnmic n.'ml'diation, but mobility would not be Tl'-

13

dured. Abo, this alternative does not include treatment. Alternati VL' Sl provides no trmtrm'nt and no monitoring, so any effective reduction could not be evaluated,

For dl'ep soils, Alternative 55 would reduce the toxicity and volume of contaminated soils through biodegradation and volatilization. Alternative 52 does not involve treatment, but would slowly reduce the toxicity and volume of contaminants intrinsically. AlternatiVl' '11 provides no treatment and no monitoring, so (lnv pffective reduction could not bl' l'vClluated.

SI/Ort-Term Effectiveness, For groundwater, Alternatiw (;2 would have no significanbhort-term risk since implL'mcnlation would result in insignificant exposure, Alternatives C3 and G4, requiring some constTmLion dllring implementation, would have minimumrisk~_ Similarworkerprotecticm measures would be taken for G2, G3, and G4. Altern"tive G1 would pn'spnt no additional shorHenn risks. since there is no constructi(ln as~()ciated with this ,lltl'rnative.


For shallow soils, Alternati ve 52 is tht, most protective over the ~hort term, ~ince implementation would result in in~ignificant exposure. Alternatives 53 and 54

were determined to be eqll.llly effective over the short tern1. The>.e two al ternan ves would pose some low risks to w(lrkers and the c(,mmunity because of excavation, hauling, and treatment. Alternative 51 would present nll additional short-term risk~ since there is no construct1('n associated with this illt('rnativl'.

For deep solis, Alternativps 52 and 55 weredl'termined to be equall y protective (lVl'r thl' slmrt term. With both alternativc~, implementation would result in minim<ll l'xp()sure ()f w(lrker~ to C(lntilmll1iltion. Altl'rnative 51 fl'qnires fh' impleml'ntation, ,ma therefore, would present nil additional s\wrt-term risk,.

lmplementability. For groundwater Alternative C1 would not require "implt'menta tion," since then' i~ no actilll1. AJtI'rnative (;2 ((mId bt, implemented easily, sinn' it ('n tails on Iy t hl' in~tallati()n of long-term monitoring wdb. A1t('rnaliV('~· C;l and G4 might interfere with somt' bast' operations near the hangars, and tl1l' sy~h'm~ w( ,uld rl'quin' m,)T(' substantial maintenance and opcratlOl1s. With Altl'rnatiVl' C4, cold weather ma) call 51' .lbllve)-jTound ript,~ tt) Irt't' 1C, wintcr maintenance i~ problPmatir. and thl' H'quired l'quipml'nt would require significant spaet'

For shall(lw soils, Altl'matiVl' '')1 wllUld require no impicment.ltion. Aitemativl~ 52 ,'mild be implemented the most l'asily, similar t(l grollnd water. Only certain accc~s rcstrictions and monitoring would bl' rf'quitl'd. With both Altcmativ('o-, 5.1 ;md S4, excavation would distllrb bact' opt'rahol1s rwar the hangar~. Permib, equipment, spl'cialhts, and SP,IO' for on-base tn'atmpnt or arrangement for off-basl' di~posal would be required.

For deep sllIls, Alternative Sl WI .uld n'quire no implementation. Altl'mativl' 52 could be implemented till' most easily. similar to shallow ~,()ils. Only cl'rtain access restricti()n~ and mlmitnring would be n'quired. Alternative 55 could intl'rfere with soml' b(t~l' operatiom ne(tr the hangars ilnd w()uld require permit:', equipment, and spl'cialists.

Cost. For gmund wa Il'r, A It ('rna t i Vl'S (;4 ($R.~ million) and C3 ($3.7 million) cost many moH' times than AlternatiVl' (;2 ($0.4.1 million). /l,ltl'rn,ltive Cl ha~ nil cost.

14

-------- ---- -----

OU 4 Proposed Plan

For illl soils, AlternMives 53 ($3.2 million) and 54 ($2.2 million) cost many more times than Alternative 55 ($(1.39 million~eep soils only) and Alternative S2

($(),39 million). Alternative 51 has no cost.

State Acceptance. The 5tateconcur~ with theprcferrl'd alternatives identified in this Proposed Plan.

Community Acceptance. Community acceptance will bl' ('valuated during the public Clllnml'nt period in a responsiw summary as part 01 tIll' ROD lm the basis of comments on this Proposl'd Piiln.

Rationale for Selecting Preferred Alternatives

AI ternahve C2 is the preferred alternative for groundWelter at all of the source areas with contaminated grmmdwater. AftE'r a thorough H'view of the various altl'rnatlves, ('(m~idpring the gmundwatl'r risk", c1E'anup tinll'~, and alternative C[lst~, it was determined that protl'ction of the environml~nt could be achieved without aggre"siv(' treatments. Institutional controls with intrinsic remediation for groundwatl'r provides pnltectkn of human health and thl'C'nvirnnml'nt with-out t)w high cost and technical pfIlbll'ms a~sociated ~ with active groundwater treatml'nt alternatives.

Modeling rl'sults show that groundwatl'r contaminatmn iltOL 4 will not migrate off sitl'. Wi th A I terna ti ve C;2, USl' of the shallow groulldwatl'r aqUifer as ,) watC'r supply will be prohibited bv ,lcn'ss restriction" during tl1(' peril)d of time it takl'Oi for natural processes to remediate the water. Monitoring will ensure that omtamillatl'd groundwater dOl'S not migrate beyond access-cpntrolkd areas. The Inng-t('rm monitoring and the fi v(~ymr review process ass(lcia ted wi th this a Iternative' will pfllvidea safl,ty net to pr(ltl'Ct other (trms of the Base' ,)r ot\wr receptors from oft-site migration of rill 4 gn Ilmd water contaminants. Institutional controls with in trimic remediation for groundwater is thl' most easily impll'mented and (()~t-l'ffl'chve illtematiVI' thilt will meet the requifl'JI1l'nts <it each of the source art'as.

Altl'fnati Ill' S2 is the preferred altemative for shallow sllils at all source areas where IllW IPvels of tar and a:iphilIt bv-products are the most Cllmmon nmtami-n,mts. ln~titutinnal controls with intrinsic reml'diation for the shallow soils provides protl'ction of human health (tnd the l'nvironment without thl' high cost, 1111cl'rtaintics, and technical prnhl('ms of mon' aggrcs- «'

~i Vl' trea tments. With AltematiVl' S2, land use restric-tiOIlS on tIl(' Base would prohibit acee:,;s and distur-

I

au 4 Proposed Plan

bilncp within the sour,£, ilreils while I1clturill processl's remediate the soil. These restrictions would be easy to implement since this ilrea is in iln active airfield. The progress ot intrinsic rpmediation would be tracked through annual monitoring. This alternative achieves the (lbjl"ctiv l'S ilt the most rl'ilsoJ)ilble .'OSt.

For deep soils, Altern<ltivl' S5 b thl' preferred alternative tor the FT A, till' ADSA, and Hangar 10/11 sourCl' arecl', Thb alternative ,vas Ch(lSen f(lr the FTA and Hangar HI /11 hecause bi(!venti ng shpuld act quickly to cle<ln up the deep soib, which l'ould .lct as a continuing ~ourCl' ior groundwater contamination at thes(' locatlon~. Alternative S5 was cho~en for the ADSA beca\lse thE' high (oncentration~ uf hydrocarbons will degrdde ml>re qUIckly with active remediation. Thi~ alternative i" a very effective <llkm,ltivl' at <I rel<ltivdy low cost for removing the Iuds ;md fud residues from thl'~e de('p ~1lib,

Alternative S2 is the prderred alternative for the Hangar 1.'> sourCL' <lrm, where, like the ~hallow soils, most of tllL' contaminants are low-level tar and asphalt bypwducts, Bl'cause of the types of the contaminants PTt'sent, thpJ ,HE' not likPly to migrate into the ground,vater in thl' future, Thit; alternative will meet the requirement:- and is abo the most Cllst dfl'cti ve. DQep ';oil c(lntamillati()n i;, not pn~~ent at tht, Hangar 8 and \4 ~Ollrce arl'dS,

The preferred alternatives wert' chosen on the basis that assumptions behind the human hedlth risk calculationsarl' Vl'ry conservative, Howl'ver, no alternative will be selected until after the public comment period. It is extremelv unlikely thatfuture fesidt'nts would Use (ontaminatcd water from the upper aquifer for drinking and showering. Upper aquifer welb are not being used for <In)' purpose, and tl1<'y are Illlt ('xpected to b(' csed in the future, It is also highly unlikely that resiJence~ w(luld be constructed III these areas, since they .lre adjacent to hangars and runways. I n summary, the prderred a I tema ti ves a re l~xpected to provide the bl'st babnce of tradellfb among all of the possible alternatives with respect to the National Contmgency Plan criteria, Therefore, the USAF, EPA, and A DEC believ\' the preferred altemative~ would:

• Protect human health and thl' environment; Comply with ARARs: Be cmt eftective; ill1d

1.'i


• Use permanent solutions and alternative technologies or resource recovery to the maximum extent practicable.


You are encouraged to provide comments on any of the altemative~ during the public comment period, You can make your comments eithl'r in writing or <It the public meetings. The public comment period is from 11 April11195 to 12 May 19'15.

The USAF will prepare a written response to <Ill significant commenb, criticisms, and new data submitted to thi~ Prop< I~ed Plan. A sumrnaryoftheseresponses will accompany the ROD forOU 4, which wiII be available in the administrative record atthe lnformation Repositories.

Public Meetings

A public meeting to discuss the Proposf'd Plan, answer questions, and receive public comments will be held fwm 7:00 to 9:00 p.m. on Wednesday, 10 May 1995 at thl' University of Alaska Anchorage, Business Education Buildmg, Room 207.

Places to f'ind Information Repositories (relevant documents).

• Bureau of Land Management Alaska Resources Library 222 Wcst 7th A venue #36 FederCil Building, First Floor Anchorage, Alaska 99513

Hours. Mon-Fri: 8:00 a.m.-5:00 p.m.

• Univer"ity of Alaska at Anchorage Consortium Library Reserve Desk 3211 Providence Road Anchorage, Alaska 99508 (lJ07) 71'6-1871

Hours: Mon-Th: 7:30 a.m.-1O:00 p,m, Fri: 7:3() a.m.--6:00 p.m. Sdt: 10:00 a.m.--6:00 p.m. Sun: Nllon-6:00 p.m.

These hours will vary according to the <lcademic calendar.


Contact for Questions

Community Relati()n~ C(lordinator Mr. Mark Davidson PublIc Affair~ Office, 3WG/PA (;421) 12th Strppt Elnwndorf Air Force Ba:-il.', Ala~ka 99506-2530 (907) 552-5755

ACRONYMS

ACM: Alaska Cleanup Matrix for Ilon-undt:rground ,lOragt: tank cllntaminated soil

AUEC: A I ,l'i ka Departm<:nt ofEnvimnmental Conservation AUSA: Asphalt Drum Storag<: Area

AFB: Air FllIU: Ba,e

ARARs: Applicahle or RekviUlt ,md Appropriate

Re4uirements

8TEX: Bcrlll:ne. Toluene. Ethylhemene. and Xylenes

CERCLA: Compn:henslveEnvlronmentaIResponse.Compensatillll. and Liahility Act (also known ,l'i

Superfund J.

EPA: U. S. Environmental Pwtection Agency

FFA: Federal j-<acility Agreement

FT A: Fire Training Area

HI: Hazard Index

ICIR: Institutional Controls wllh Intnnsic Remediation

(JU: Opl'rable Unit

PCBs: P()lychlorinated Biphenyls

RliFS: RemediallnvestigationlFeasihility Study

RME: RL';]",llllahle M,nimum Exposure

ROD: Record llf DecIsion

S])W A: Safe Drinking Water i\ct

16

au 4 Proposed Plan

TCE: Trichloroethylene

UCLs: Upper Contidence Limits

lJSAF: U. S. Air Force

VOCs: Volatile Organic Comp()unds

GLOSSARY OF TERMS

A.ir Sparging: A form of treatment in which air is injected into groundwater. The bubbling air enables the contaminants in groundwater to become airborne, or volatilize.

/iIJuifcr: An underground body ()f water that occurs at various depths.

ARARs: Law~ and rl:'gulations that {'stabli~h cleanup levels inr sites with contamination.

Benzene: A carcinogenic compound typically associ-,lted with fuels such as gasoline, kerosene, diesel, and ~ let fuel. Along with ethylbenzpne, toluene, and xyll'nes--also associated with fueb-benzene makes up the contaminants known by thc acronym BTEX.

Biopiling Treatment: A form of treatment that enhancl's natural degradation processes to reduce and l'liminiltc contamination in soil. Soil is transported to a facility where ilir and nutrients are added into the contaminated material, incrcasing microbial populatiom;. The nrganisms then degrade the contaminants.

Bioventing Treatment: A form of treatment that enhances natural degradation proCt'SSe5 in the ground to treat 51 Iii contamina tion. Air and nutrients are injected into wdls within areas of contilmination to accelerate degradation by microorganisms. Unlike biopiling, soil llnder~oing billventing is not l'XlilVnted.

Deep soils: For the remedial actions planned for OU 4, deep soils are those found at depths greater than 5 fect. Contamination of deep soils has been found at Hangar 10/11 and the ITA and ADSA.

(Continued Oil Page 19)

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OU 4 proposed Plan Elmendorf Air Force Base

USE THIS SPACE TO WRITE YOUR COMMENTS y,)ur comments and suggestions about the remedial altematives discussed in this Proposed Plan are important to the Air Force. Comments that the public provide are valuable in helping the agencies select a final remedy for OU 4.

You may usc the space below to prepare your comments. When you are finished, please fold and mail. A return address has been provided on the back of this page for your convenience. Comments must be postmarked by 12 May 1995. If you have questions about the comment period, please contact Mr. Mark Davidson at (907) 552-5755.

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Nanle _____________ _

Address _______ _

City

Stat" Zip

,,..

PUBLIC

COMMENT

Name __________ .. __ . _________ _

Address

City

State __________ Zip_ ___ _ __ -------

Mr. Mark Davidson 3 W(}jPA

6920 12th Street Elmendorf AFB, AK 99506-2530

SHEET

Fold along dashed lines, staple, and mail.

I PLACE STAMP

. HERE 1_.-

I

au 4 Proposed Plan

GLOSSARY (C ontinued from Page 16)

Ecological Risk Assessment: A study of the risks to plants and animals that can 1w attributed to sitp contamination

Groundwater Table: Thl' groundwiltl'r ~urfilcl' In undl'rground rot k or soil.

fluman Health Risk Assessl1Jmt: A :-;tud y of thl' risk~ to hum,m heCilth that can be Clttributed to site contaminiltion. The st11dy can be divided into cancer risks and nllnemCl'r ris).. ".

Institutionul Controls: Phy~ical or legal barriers such a~ fences and deed restri~tions that limit acccss to c,)ntaminatcd .Irms. They (an be applil'd 111 CI variety of fomls ttl groundwater and sllils.

IntrinSIC Reml'diation: TIll' pruCC'l' whereby bacteria and other mil f()organj'lms that occur naturally ,'lfl' allowed to feed on the cuntaminants found in the soil and the gn,unclwater and. OVl'r time, reduce the cont<lminant kvd·,

nI'S/kg: Milligrams of contilminant per kilug:ilm. of sl,il; used to mca"ure dq.!;rt'e (if ',oil C( ,ntammahon (part" per millH JI1). (This tl'rm apP(,drs on ly in Table 1.)

Alonitoring: \l(w,un'rn('l1ts Ilf SOl b and ground water qllality to dl'll'mlinl' th(' ('dl'nt of 1'll11larninaliul1 ill1d the degrce to which it h ckanl'd up.

N"tional Contingency Pilln: Thi~ Ipdl'ral plan implements the fl'qllirl'ments llt CERCLA. It provides the organi7ation structure and proCl'dllrl'S for addressing fl'derfll Superlllnd siteo_

Operable Unit: An area within a tiitl' thai is composed of similar contaminatilll1 and is similarl} man<lged to al hil'Vl' clt_,<mu p.

lY


PCBs (Polychlorinated Biphenyls): A grllupof fC'lated compounds typically used in electrical tran"former".

Plume: An area of groundwater that is bdicved to be con ta mina tl'd.

Proposed PI all: A document prepared to inform tl1l' public abollt altcmalivcs that w('re considered ~()[

cleaning up a contaminated site and which altematIve or a IIl'mati ves have been identifil'd as the preferred alternative( ~). Thl' document encourages public comml'nt on all alternatives.

Remedial Action: Actions taken to eliminate, reduce, llr control the hazards posed by a ~i\('.

RIll-'S: Two interrelated CERCLA (~ee Superfund) ~tudil'''. Thl' RI is conducted to identify the types, ammmts, and locations of contamination at a facility. It also ('valu<llcs possible risk to the public and environml'nt from ('xposure to contamination. The FS identifies, ~creen~, and ('valuates differt'nt .,Itl'matives for c1eamng up l-ontaminati()n.

51lallow soils: For the remedial actiom planned for au 4, shalll 'W soib are those found at depths less than ') fl't'! Cont.lmination of shallow soib has been found "t l'ach of the OU 4 source areas.

Superfund Program: The federal hazilrdou~ wa~te cleanup program ddministered by the Environmental Protection Agl'ncy. Its formal titk is the Comprehensivl' Envin.nmenti11 Response, Compensation, and Liability Act (CERCLA).

TCL: rrichh)roethylene. A volatileorg,mic compound used ,I:' a ckaning solvent.

f!glt: Micrl)gri1ms of contamini1nt per liter of wilter; llSL'd tll mL'.lsun' degree of groundwater contamination (parb per billion). (This term appl'ilrS only in Table 1.)


PUBLIC MEETING

A public meeting will be held at the University of Alaska Anchorage

Business Education Building Room 207

on 10 May 1995 (Wednesday) from 7:00 to 9:00 p.m.

ELMENDORF AIR FORCE BASE 3 WC/PA 6lJ2() 12th Str'~'Ct Elmmdorf AFB, AK IJ9506-2530

A ttn: Mr. Mark Oa vidson

au 4 Proposed Plan

April ]995

ELMENDORF AIR FORCE BASE, OU 4 The Proposed Plan for Remedial Action

INTRODUCTION

Tht, u.s. '\ir Force (USAf), Regwn l() llt the U.s. Endronml'ntal Protection Agency (EPA) and the Alilska Department of Environmental Conservation (ADEC) are' requesting puhlic comml'nts 011 this Proposed Pial I. It addresses ckaTlup of contaminated soils ,mel groundwater at Operable Unit 4 IOU 4) of Elml'ndort Air Force RilSl' (AFB). OU 4 is an drea of soil ,md h'TUlmdwatl'r contamination adjacent hl the main nmway (Sl'C Figure 1, page 2).

In· ... lIf.,'ust 1YY(), EPA addl'd Elmendorf AFB to thl' Nati,mal T'riorities List of hazardous wastl' sites that neec' til hI' cleaned up. On 22 NOVl'mber 1991, the USA F, EPA, and ADEC signed the Federal Facility Agrl'ement (FFA)for Elmendort AFB. Under the terms df tlw agn'ement, all rpmedial response activitips to prokct puhlic health and welfare and thcl'[)\"ironment will he conducted in accordance with applicable fedL'ral ,md statl'lilwS.

fhis Pmp)spd Plan is based on a report entitled the Re1l1"diallilvestigatian/Feasibility Study Report for Operable dllit 4 The Pmposed Plan highlights kev information from the remedial inwstigationl feasibility study (RIfFS) report. The RIfFS report and other information relilted to this proposed cleanup are availablt· for public review in the Information Repositories, which are at the locations Iistpd under tll[' Community Participation section of this Proposed Plan. The community is encouraged to comment on this Proposed Plan during the public comment period. See thl' Community Participation box at the bottllm of thi~ page for more information about thl' comment period and public mepting.

Note·-Thn>lIghout thi, Propmed Plan, speCIal key tcrms are highlIghted In bold face, italics. when they first appear These terms appear hoth III the text and In the G lossCll). y,)U are encouraged t(l consult the C1lossary If you would like it more detailed explaIlation of any of these terms.

The Proposed Plan has four purposes:

1. To Identify the preferred altemative(s) for remedial action (cleanup) at OU 4 and explain thl reasons for the preference;

2. To describe the nature and exknt of contamina tion and the remedial options that were l'valuatl'd in the RIfFS report;

3. To o,olilit public review of and comment on ,III lit

the <lItematives described; and

4. To provide information on how the public can bl' involved in the remedy selection pwn'ss.

This Proposed Plan is part of the public partieipaDo)) required under Section 117(a) of the Comprehellslvl' Environmental Response, Compensation, and Liabil ity Act(CERCLA), commonly known as the "Supl'rfuIlLJ Program," as amended in 1986.


PUBLIC COMMENT PERIOD FOR OU 4:

11 April 1995 to 12 May 1995

PUBLIC MEETING to Discuss Remedial Action Alternatives and Receive Public Comments:

Wednesday, 10 May 1995-7:00 to Y:110 p.m.

Univprsity of Alaska Anchorage

Business Education Building

Room 207

Elmendorf Air Force Sase

You are encouraged to provide input on all of the altcrnahves. Your comments can make a difference in deciding which cleanup alternative will be chosen. The USAF, EPA, and ADEC will not sdect a cleanup alternative until all public comments have bt'en reViewed ,md considered. Changes to the preferred altemative or a change from the preferred alternative to another alternative may be made if public comments or additional data indicate that such a change would result in a more appropnate solutlOn. The ~I:'le(ti()n of a cleilnup alternative will be documented with a Responsiveness Summary ina Record of Decision I ROD).

SITE BACKGROUND

Elmendorf AFB is located approximately 2 miles north of downtown Anchorage, Alaska (see Figure I). It is bordered to the north and west by Knik Arm .. to the east by Fort Richardson Army Post, and tn the sillith by a light industrial area and land owned by the Alaska Railroad Company. Elmendorf AFB was op(·ned in 1940 and provides defense for the U ni ted States through surveillance, logistics, and commuruciltions support. OL 4 is lo(att'd in the central portion of the Ba sc, and includes most ofthe area around Hangars 8, 10, 11,14, and 15, a~ well as the former fire training area WT A) and the l'\5phaJt Dmm Storage An'a (ADSA).

OLi 4 is situatL'd on rPlati vely flat terrain at an appro ximatt' elevation of 1 liS feet above mean sea level that slopes :.;radually to the sou thw('st. Cmundwater is divided into an upper and d lower aquifer by an impermmble layer of silts and clays called the R()oth'gger Covc Formation. ThE' s()il above th(' dividing layer is mach· 01 sandy and gravelly sl~diments that annw grnundwater to flow. Water from thi~ .lquifer ~s not USt'd for drinking water in the Bast' arpa. Wat('r 111 the upper aquifer flows to the south and west across au 4. This aquifer is influencpd by the pn'sence of the Elmend()rf M()raine, which ach a:i;1 groundwa ter barrier to the north, and by Ship Cred., which is the point of discharge for the majority of upper aquifer flow to thE' south. TI,e lower aquifer is a bdckup SClllTCe of water f,)r ba~(' residents, industrial purposes, nlllling water for the powl'r plant, and fish production at the fish hcltchcl).

The USAF identified several potential sources of groundwater and soil contamination at au 4. Contamindnts include jet fuel, gasoline, diesel fm'l, kerosene, trichloroethylene (TeE, a solvent), BTE X (ben-

2

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au 4 Proposed Plan

~\~··~a· ..... .-, '." . r;:L~~NOORI" ."

...... - .... "' ... ----- .

/ °i~ =~~=~iiii-·2~i !

... N

j' ELMENDORF AFB / OU 4

j I Ii ~

( ) I

~l ~i ~"

L--------..

Figure I. Location Map oj Elmendorf AFR, Alaska

zene, toluene, ethylbenzene, and xylenes-volatile compounds from fuels), and asphalt. Sources ()f these materials were leaking underground fuel storage tanks and related valves and pipes, fuels and s(llvent~ used in firc-fighting training, dmms of asphalt ston,d on the ground, and floor drains from hangars. Rdeasl's of these contaminants, which occurred between thtlate 1950s dnd tht'\ate 1980s, were investigated by the USAF.

There are four principal buildings located within tIlE' western part of au 4 that were former source areas' Hangars 8,10, 11, and 14. The FT A also is located in ttl(' western part of au 4. In the eastern part of au 4, thert are two former source areas: the ADSA and Hangar 15 ncar BUilding43-41O. All seven former source areas an being considered for cleanup. (See Figure 2, page 3 )

The hangars were defined as former sourn' area~, because each contained floor drains through which hazardous materials were believed to have been re-

OU 4 Proposed Plan

Figure 2. OU 4 Study Area,~

leased into the subsurface via dry wells and/or leach fields. The FT A was identified as a former source area because of fire training activities conducted tllPre. The AD5A wa:; identified as a former source area because asphalt had either leaked or spilled from the storage drums.

As a result of their recent invl'stigations, the USAF has repaired or removed all kn()wn sources of contamination at OU 4, and access to contaminated arms is now controlled In the last few years, the USAF has performed such work as the removal of the old asphalt drums and revegetation of that area, the deactivation lIf the FTA, the testing and repair ot all pIping and tank~ at OU 4, and the reTOuting of OU 4 hangar drainage.

NATURE AND EXTENT OF CONTAMINATION

ContaminationatOU 4 was found in both shallow and deep soils and in ground watl~r. The sources and types of contamination and the extent to which th(' soils and f,JT()tlndwater have been affpcted are di"cussed below.

3


Contaminants

Soils. Soil contamination at OU 4 was detected in samples of both deep soils (> 5 feet) and shallow soib « 5 feet). Gasoline, diesel, jet fuel, BTEX, and other fuel-rplated contaminants are present in the soils at concentrations exceeding cleanup standards at the areas mmprisingOU 4. Polychlorinated biphenyls (PCBs) also were detected at very low concentrations in ~(,il:at isolated locations, but were well below cleanup standards and acceptablE' nsk. Low levels of he'l\Y' end contammanb, such as asphalt and tar by-pntducts, wcre also commonly found in the OU 4 soils. TIll' maximum concentrations of chemicals detected in .,(Ii];· tha t exct'ed standards are shown III Table 1, pagl' 4

Asphalt-typecontaminanb were found at low levP)~ at each of the OU 4 source areas in shallow soil samples. These contaminants were detected in isolated occur· renct's that were generally below the acceptable nsk ranges. Since these types of contaminants are relatively immobile, they do not tend to percolate into til(' groundwater. If a hypothetical resident eab the ,'I III taminated soil, there would be a risk.

In the deep soils, the primary contaminants deteckd were fuels (diesel, jet fuel, etc.). These contamin,mts although posing no current risk since they are buril'd, can percolate into the groundwater and may contrlh· ute to groundwater contamination some time lI1 tlw future. Because low lewIs of fuels were relati vPl\ widespread in the deep soils atthe FTA at depths (if !JF' to 40 feet (about 10 feet above the top ofthe ground W.i·

ter), some action may be required to remoV(' the iud, at this location for protection 01 the groundw.ltcr. Relativdy high levels of fuels were detected in tht' deep soils at one location at the ADSA and at two locations at Hangar 10/11. This contaminatioIl W,\;·

detected at depths of about 25 feet above the groll1ltl· water table. Because of the high levels of fuels de· tected, ~()me action may also bt' required at tlWSl' locations to protect the groundwater from future con· taminatiun. No other fuels contamination in the dt'l'P soils at OU 4 poses a significant risk to groundwater

Groundwater. The groundwater screening program identified several contaminant plumes in the upper aquifer at the source areas. The plumes are Lotally contained on base property and do not currt'ntly affect any groundwater users. The organic contaminants llt concern exceeding standards in groundwater includl' fuels, BTEX constituents, and chlOlinated solvents. f",


groundwater plume was identified in the ADSA area. The maximum concentrations of chemicals detected in groundwater that exceed standards are shown in Table 2, page 5.

Five area~ of groundwater contaminatinn, or plumes, were identified atOU 4. Oneplumeof fuel-related and solvent contamination was detected moving to the southwest (in the direction of groundwater flow) from the FTA.l11is plume extends to thl~ west of Hangar 14. Probable,ources of the plume have been addressed through actiom that include the testing/repair of a large underground fuel tank and lint's near the FT A, and the temlination of fire training activities.

A second .. small plume was detected moving to the southwest with groundwater flow from Hangar 11 Only one of four wells indicated contaminati( Ill. Relatively high levels of fuel-related contamination were dl'lectl'd in this plume, which originates from a valve pit to the west of the hangar. Again, action has been taken to address the source, which indude~. the decommissioning of the valve pits in 19Y3 and the remuval--schl'duled for 1995--01 three underground storagt' ta nb that were served by the valve pits. These tanks wen' investigated as partof the State-Elmendorf Environmental Restoration Agreement and were determined to be leakmg.

A third fud-related plume, coming from Pump Hou"e 2, was detected near Hangar 1 O. To address the source of this plume, the pump house has been te~ted and repair~ madl' as needed. An effort has also bel 'n made

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OU 4 Proposed Plan

to address the sources of contamination at the remaining two plumes at OU 4. In both of these plumes, the levels of contamination detected were lower than the )se at the other plumes found.

A groundwater model that predicts the migration (It

contaminants in the groundwater has been developed for Elmendorf AFB. The model considers the type~ (It soils, the direction and rate of movement of h'Tound .. water beneath OU 4, and the type and amount (11

groundwater contamination. The model shows thill benzene and TCE (indicator contaminants) in the OU 4 area will migrate approximately 1000 feet over thl' next 15 years, generally to the south-southwest. 111l' areas of Cllntamination are predicted to broaden forth,· next 10 years, and the concentrations of contaminant-, will diminish. The model shows that within 15 year~ they will have decayed and dissipated to below acceptable cleanup levels, assuming that no additionalleab or spills occur.

To support these modeling results further, Elmendort conducted a detailed study of the natural proccssc::. occurring today in the groundwater at OU 4. Thl' purpose I)f this study was to look more closely at th .. activity of microorganisms feeding on th,J nmtarnlnants, and other natural processes that remove omtaminants from the groundwater atOU 4. After-colkctingand evaluatingOU 4soiland groundwater sample:, the study confirmed that contaminants would be fI'

duced to belo w cleanup levels long before they w01lld reach other parts of the Base or Ship Creek.

Table 1. Soils Contamination (Shallow and Deep)IACM* Standards (Level D)

Maximum Concentration (mg/kg)t

Contaminants Standard Source Area of Concern Shallow Deep (mg/kg)

FTA Kerosl'ne 2200 N/A 2000 Ca.,(iline N/A t

3710 1000 --------- --- ----

H;mgar1ll/11 Ca,(lline N/A 4100 WOO ! I :)icsd

N/' I 5'lOO 2000

i Kero,:)l'ne _____ N / A___ 620 100 -----1----.- ---- --t----- --- - --- --ADSA ~ Di,,,, 110,000 N/ A 20()O

.iet Ful'l 21 DO 13,000 2000 Xylen("s N/A hlO Ion Cas(l\inc N/ A 15,600 1000 -1--------. .----------.

* ACM ,= Ala.,ka Cleanup Matrix for non ·underground storage tank contaminated soil. tmg/kg =, milligrams of contaminant per kilogram of soil; equals parts per million. N/ A ,= Not above standard. ~()t~~-Soil cuntamination at Hangars 8,14, andiS/Bldg. 43-410 was not above ACM standards.

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4

au 4 Proposed Plan

The findings of both the modeling work and the biological Shldy conducted on the groundwater at OU 4 indicate that contaminants should not migrate beyond the tlightline area of Elmendorf APE, and that through the natural processes already occurring in the groundwater, contamination will be below acceptable levels in a reasonable amount of time (1.5 years). These finding~ are supported by thl' fact that even though the S01] rcps of these plumes may ha ve f( Irmerly been active for :ievpral years (especially ilt the fT A), the plumes have still not mih'Tated very filr from their sources.

SUMMARY OF SITE RISKS

Analytical results from 50il and groundwater samples were compared with cleanup standards to identify possible contaminants of concern (contaminant levels exceeding standards). A human health risk assessment was then performed to see if therE' were any pob'ntial negative human health effects fwm the contamination. An ecological risk assessment was u5ed to estimate the efff'cts of contaminants on plants and

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animab. On the basis of the risk assessments and cleanu p standards, areas requiring remediation b) pn 1-

tect human health and the environment were identified. The standards and risk assessments are discu~sl'd below_

Human Health Risk Assessment

Two important measures are used in human health risk a~~essments: excess cancer risk and hazard index (HI). The cancer risk level is the additional chance that an individual exposed to site contamination for a lung period (30years) will develop cancer over the cour~l' llf a lifetime. It is expressed as a probability such a~ 1 X IW (onein one million). Typically EP A regards the thrl'shold for action when risks exceed the range of 1 X JC!-4 tl) 1 X 1O~ (between one in ten thousand to om' in nne million). The HI estimates the likelihood thatexpo~ur(' to the contamination will cause some negative health effect other than cancer. An HI score above 1 indlc.ltl'~ that some pe()ple exposed to the contamination may experience at least one negative health effect.

Table') Groundwater ContaminationlSDWA * Standards -. ,

Contaminants Maximum I Source Area of Concern Concentration (~g!L)t

FfA

Hangar 14

Hangar 11

Hangar ~/10

Hangar 15

, I-Trichloroethane 1,1 1,1 1,2-Tet TC 1,2-Bl'n

Dichloroethene Dichloroethanc rdC hlorOl ,thene E Dichloroethene 7ene -------1= ,7C1W

----... ------

Ber

zene I ylbenzcnl' i

._--_._--- -----~~~ ... ---t-,zene

Ben Eth Tol

Ber ---- --- -- ----------

rilchlorOlthene Tet TC t:

----

I I

L

242 13.7 12.1 40.5 74.7

741 391'

2()7

2000 1360 5590

266

19.5 23

'SDW A", Safe Drinking WatLT An. tllg/L= micrograms llf cunt.-ltninan t per liter l)f water; equals parts per billion_

5

---.--

Standard (j.lg!L)

--

200 7 ')

5 5

70 5

- -_._-

5 ----------- -_ ..

5 700

WOO --~~-- --

5 -_ .. ----_._- - --

5 5 ---------

Elmendorf Air Force Base au 4 Proposed Plan

Thp human hl·alth risk aSSl'ssment ccJl1siJered current ,md hI ture residents, workers, and visitors as possible l'xposed populations. People could pntentially come intu contact with the contammants through :,howering, skm contact, ingesting (e,lting) dust or sllil, and Jrinking groundwater. Tht' highest SOlI risk is frum incidentill in,'-';l'stion of shallow soih k 5 feet) h .. hYP(l-

thetical residents, and the highest water risks arc trom showering with and drinking water from the contaminated aquifer by hypothptical rpsidents. These higher estimated risks could occur only if land use "vere tc' become residential in the future and if the groundw", ter were to be drawn as a source of drinking walc'T This sel'nario represents the most conservati\"(' (high·

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Source Area

FT"A

Hang,lI' 14

Hangar 10/11

Tal,le 3. Hllman Healtlt Risks

Soil Risk' -----

Sl1a llow Soils i < 5 jeet) Kl'.,ia~.nti,11 1- Current--

(RME)" Ocupati(lnal' - ----------- - ---- - --._--

2.7),W' <10' - ---- "-- --- -- --r-----~

2.S X ](f" I ~ 10"'

Deep

--,:"sJjLsJ> 5 feet)

CunstnlCti,'n t!

Workt'r" -------

~:~ ___ I < W·" r

Chemical(s) Driving the Risk

Fuels and fuel residues

Fuels and fuel residues i

.----- - j' .--. -------j----------.t-

4.1 X 1(},' IS X 10'" < w·' ' Fuels and fuel residues I I ___________ --1 ________ . ______________ ~

~::~~,~-----=~-:j~~: ~" ~~: ': ,~ ~t ± : : :>~=:;~::: ::~;:~::: _ _ __ l()' I <1 W ! Fuel5 and fuel residues .----.---~--------.--J-------_______________ ,

ADS;'. I

-~--+-42 X II)'

Grollwdwater Risk'

------------ -------1- -- ------. ---------------, :K~sidt ~ti~l'kMEY r FutUT(, OTllpiltlOnnl'

2.1 )( WI HI = 2 '<, 15 X lO"'; HI = <: 1 I Bpnzene, ethyl benzene, tolul'ne, i :'0 I ven ts

FTA

---------- -1-_ .. _---------- ------- ------------ ------

~l~n~.~~:. ______ ~--2.~X_~~~ ~ ~~ = 1 I-t-~2 X ~~~ H~~,,:-_1 Benzene ______ I

~l~n~,~~~~ ~j.:...~~' _l~ = Y 1 __ -=~~ll-l; HI-=-~~l ____ ~ Benzene, toluene, ethylbenzeI1c _ i

~::~~;;1l~ __ . __ ~~~~~'~ __ j ~: :::'~-E~'~::::~~:~~omm"fh,:,,--i ___________ . ~ _____________ .L

·'R.hk, ,He cakulated by using the lJ~'!, upper Cllni,dencl' limits (UCLs) for Cllntaminants present. TI1f' YC;'); tJCLs repn",ent a Clll1'l'rviltiv(' (·-;timate of tIlE' "~V(lrst ca_c" conti' rninati'll1_ "Exccs, c,ln"'r risk., c(lnservativdy Cl,Qll1wd fm:;il years of expI)suTL' (drinking grLlundwiltpr, nll1tilct with snil, ('tcl b\ futun l'l'-id( 'nh (Rea'ionabll' M,l ximum Expuciur . .'l. Exec,·, Cai(C(T nsks cunscrvati\l'1y .1 __ 111lll'd fnr 2~ years lJf expnsurc while w()rking '1I1 ,ite under current cunditi,l[lS.

"FXCl'" C;JIlC( 'r ri<;k.~ c(lnserv.1ti\ l'ly .1 "lIJlHd fllr 1 vear uf exposure during nn-,itl' construction wurk (digging, etc.). 'Excl's', (.Hlc("r ri,k;, c()nserv.1tiH'ly .1"lln1vd felr 2~ year, elf eXpnSUTl' while 'N, lrking Illl site undcr hyputhetical futUfl' cundltlllll', (clrinking gruundwilt('r, dC)_

HI = t-;a;r.-<rcl Index (<1 mca,urc "f nunc,1Tcinllgl'ni,' riskl.

au 4 Proposed Plan

est exposure) set of assumptiom used in the risk assessment and is known a~, thl: Reasonable Maximum Exposure (RME). If land use is restricted in the future so that Ilil drinking water wells can be installed in the shallow aquifer (as currently exists), the water in this aquifer would continue to pose no risk to human heal th or the en vironment. Level S OJ con 13 mina hon in deep ~()ib (> 5 feet) pose no human health risks.

Th(~ area,; where the exceOiS cancer risks e)..ceeded 1 X 1Il-' (one in one milhonl or the HI was above 1 for Oil'veral of the risk scenarios di"cus,~ed above an' listed in Table \ below.

Ecological Risk Assessment

An eco\ohrlcal risk assessment was conducterl to assess which plants or animals may be exposed to contaminanb and the likely effects of that exposure. Animals ma:v be exposed to contaminants by eating contaminated plants, animab, .and soil; coming into contact with the contamination; and (if they burrow) breathing soil vapors. Plants arc exposed to contamination through the soil or water. Plant and animal efft'Cts Wl're considered in the ecological risk assessment

Tht' remedial investigation did not identify significant ecological impacts warranting action. Potential impacts on representative wildlife (moose and meadow voks) consuming plants grown in contaminated soil Wl're calculated, but no significant impacts were determined to be present.

SCOPE AND ROLE OF RESPONSE ACTION

Tht' au 4 remedial investigation Identified groundwater and soil contamination -primarily fuels and soh'ents. To remediate (clean upl the groundwater and soil c()ntamination most effectivdy, th(· preferred treatment alternatives will target both shdllow soib and deep soils. The respon:"t' action, or method used to remediah' the contamination, at au 4 i~ part of a baspwide effort to clean up contaminated media.

7


The response action addresses impacts to human hml tli and the environment through the following:

• Prutecting human health and the environment h~ reducing cancer and noncancer health risks to withir established health guidelines;

• Meeting the state and federal environmental law: and regulations for the specific contaminants, actilln~ and locations;

• Selecting remedial alternatives that include tn'at ment to the greatest extent practicable; and

• Selecting remedial altenlatives that are cost etfl'c tive and consistent with other aus at ElmendOrf AFB

SUMMARY OF ALTERNATIVES

To clean up the contaminated groundwater and ~,oil~ at OU 4, a wide range of possible alternatives wa~ conSidered. In general, there are many potential <>ptions available to remediate groundwater and snil'i The five most promising options were chosen (.n tht:, basis of effectiveness, implementability, and cost T (l treat gnmndwater, the analysis considered four a; ler· natives; for soil (both shallow and deep), five alte:lliltives werl' considered. Each alternative is discussed (In

the following pages. A "Go represents an alternatlvl' considered for groundwater, and an "5" represent-; an alternative considered for soils.

Alternatives G1 and Sl: No Action (Groundwater and Soils)

Alternatives G2 and S2: Institutional Controls with Intrinsic Remediation (Groundwater and Soils)

Alternatives G3 and S3: G3 In Place Air Sparging (Groundwater) 53 Excavation and Recycling (Soils)

Alternatives G4 and S4: G4 In Place Bioremediation (Groundwater) 54 Excavation, Biopile, Backfill (Soils)

Alternative 55: 55 In Place Bioventing (Soils)


Alternatives for Treating Contaminated Areas Throughout OU 4

Th,> five altl'mativcs are dle>scribed below. 11w cost of Al t(>rnatives 2 5 includes up to 30 yl>ar~ of m Oil/to rillg grollndwatl>r ,md/or soib for the> contilmin,lIlts of concem The monitoring assumption f('r eilch a Itl'rn,lti Vl' is based on theestimilted time (in ye,lrs)to cll'iln up r?;roundwatl'r ,md/or soils til acceptab\t> levl''''. 111(' ,1(tual monitoring program will bl' dl'Yl'hlpcdlS part ,If tlw design (If thl' sl'lectl'd a Itt'rna tiVl'S. The Cl h ts and time of deanu p for each of tlK' alternati Vl'~ arc ,11llwn In iI tahit' bcf(lre each alternative i.., cksnibed.

Alternativt~ (.l No Action (GroUlldwutl'r) Alternative 51 No Action (5)0;/5)

-EVctlllatllln ot t1w no action ,tltern.ltive is rl''1uin'd umkr CERCLA as a baseline rl'flL~:ting current conditions withont any clmnup. Thi" aItprnativl' is lI'ied fm C1llllpari..,(JI) with l'deh of tlw Iltlll'r altl'mativ{'s, but dut'.., nil' include any long-tern1 monitl,ring, ((,ntmb, ,)r ,1(((',,, nstriction::-. There ,lfl' no (('sis assl,ciatl'd with thi; alternativl'.

Alternativt' [,2 Institutional Controls with Intrinsic Remediation (Groundwater)

~ A Iternative 52 Institutional Controls ~ with Intrinsic Remediation (Soil,)

......... :: ::::::: .........

..... , . ::::j:;:j:;!j: :~@II@~::~

r.::v:;:~::V:

'~---~---~-"-I' -~.---.-I C2 Cllsb (Thllu'ilncj., ,)t $)

,----~-~-I're'{'-;.;t

: SULlfCl' Area I! Clpitill I Annu,\l WllTth :-----~--- -,~~-~- --~----

[FTA I 24 r 1ll 1;~ :Hdngar;) _ I 13 I 1(1

III il ngar ill /11 I' I () i t: 71) I ~ - , 'Hangar I,j I Y I ·~H

b,,_,~_~r_ :~_, __ ~~1_~_!, ______ ~) __

Tim(' tu C](\lnUr

(V'''lf')

13

H

13

7 7

au 4 Proposed Plan

___ n~ -1 =§ Clh~' ~ ,and, ot S) I : I Present

SuurCI' A~~~capltal i Annual I Worth

FTA I 21l 9 7(', t

Hangar H I 4 3 Hangar 10/11 i 12 (', Han-g;1;:-14 [4 :\

- ~ ~ - . ~t

~~i;~~~ __ l_~~~

In 27

12 ]4

Tinw tu Cbmup

(V( .If')

X

11

2

Groundwater ;md soil would be remediatl'd b\ nat\lral processe~ (phy~ical. chemical, and hiul()gic,ll) tlldt reduce contaminant concentrations. Both tlw modeling rl'Oilllts and the biologiml study conducted dt OU 4 confim1 th,~t intrinsic remediation would e1mn LIp tbe contaminalL'd media to beIL)w acceptabk Iev('I:; in .~

rt'asllnilbleamlmntoftime. Whileintrinsicfl'ml'diation is working, land use restrictions would be med t ,) limit access to contaminated groundwater ilnd soiL n1l'~l' would prohibitc(Jl1structiol1ofresidenc('s and groundwater wells OVl'r areas with contaminant plumt~s and pmhibit t'xcavatilJll of soil in areas of soil cont,lmindtion that exceed acceptable levels. The Air forct' wllulJ C(lntinul' t(l monitor grollndw,lter and soil qU<llity it r the durilll(tn (It this altemativl'. If thl'rl' i~ anv IIldico,tion that intrinsic remediation is not achil>ving till' clt'anup Il".'('J.., within L'xpl'ctl'd timl'framl's, tlw fl'm('dial action.., "viII be rl'evaluatl'd and additi()nal .;ction will be tah'J) it nl'cl'c;~ary.

Alternative G3 In Place Air Sparging (Groundwater)

:-:-;-;-;.;-

:~~ili ~

------~- C3 Cush (Thllusands ot S)

f'resl'nt -.:SllurC{' ~~"l ~~ Annu.]I' Worth

FTA h;O 152 1h42

l:l~I-wI~ H 7ft7 811 '!'12 Hangar lO1l117] 5,~ JHlJ

HarWIT14 115 114 -- -- --- - - - t-

l:l~~ngaJ'_I-,; ______ I3.~_~~_~ __ J:\h

Tim{' ttl Ck,lnup (vcar,)

'I

OU 4 Proposed Plan

In Alternative G3, air sparging wells would be installed in the area of contaminated groundwater. Air would be injected into the wells and be spargl'd (blown) intr) the groundwilter belm\! the water table. As the air pa~scs through the contaminated groundwater, the contaminant~ of concern would bI~ ~(ripped from the watf'rpha~eint() the gas phase. In addition, ~nme(lf the 'lxygen w(Juld dissolve into the h'Toundwatl'r, creating ,\TI iwrobic l'nvinmment that would ('nhanct' biodegradation of "orne of the remaining ctlntamimmts. Some of the cllntaminants could migrate to the land surface and he emitted to the atmospht'rl'. This aItl>rnativl> also W(JU Id rPly on li\TId use re"tri('tion~ and the moni toring program described in Alternative (,2

Alternative S3 Excavation and Recycling (Soil)

-I 53 C(),;::(TI1,-'~~~;)d~ :~j $) ----~- ~-~~J'~,ent

SOllTC(, An'a Capital AI~r2..u~~_~~~lrth

FTA 187() II 187(, ---

Hail!,'.!! g 13() i1 Dh

H.iln!'ilT 10 i 1.1 314 (I :114 Han!,ar 14 JIl7 II JIl7

HanharlS I 1111 I] 11>1

AQ:3.~ __ J----.l74 .. ~ _ II .. _~~_ :\'4

Timet" Clmnllp (yeil.".:'.)_

1 ----

AI ternahvl' S3 consists of exca vating the contdminated shallow soils i\TId transporting them t() a commercial recycling facility in tht' Anchorage arpa. Excilviltions would be backfilled with ckan :-;oil. At the recycling facility, the contaminiltl'd soil" typically are treated in a low .. templ·raturc thermal trmtmentunitdesigm·d to remove vol.ltile con taminants fwm the soil. 11w soil is then recycled for road bast' or other projl'Cb. TI1is alternative was developed for "h<lllow soil ... (14,YO(] yd ' ) (lIlly, because excavating all contaminated dcep s(lils (10,4()O yd') would not be a ('()~t-df( 'ctive (lr k'chnic<llly imsibll' altE·rnative.

(I


Alternative G4 In Place Bioremediation (Groundwater)

C4 C()~ts (Thousands llf S)-[-r;~~ ~ ."

_ I ['resent CI":llltll' Ca ita] Annuill i Worth , (wa,'

I ---l--~'.- -

843 381 31]7 i'

Source Arm

ITA Hangar 8 . 1h40 " (;75 34(lY

~~.a. ngar ]() /11 444! 147 inC!

rla l1gilT 14 228 J 75-+ 484'1 Hang~L2~~,---_4:.::J.:.:.8 ___ ~_ Y:;~ __ •

In this altemative, a sene" of wc>lb would be in"talll'd to extract contaminated groundwater. Extrat'h'd groundwatl'r would be piped above ground tll a Inl\·

ing tank., where the pH is adjusted and (lxygcn and nutrients an' added. The groundwater would then bt, reinjPctt'd into the aquifer through injection wdh It' biodegrade dissolved c()nt;~minanb in place. Wh('11 compan'd with nther contaminants, the principal ('Oll

taminants at Hangar 15!Building 43-4l!l and part (lj the Fr A are more resistant to bioremediatiol1. Thl'n'forc, Alternative G4 would not be as effective at tmlt· ing the groundwater at these two si tee;. Thi~ altema ti \" also wlluld rely on land u~c restrictions and the m·)Jl(toring pnlgr.lm dpscribed ill Alternativp C2.

Alternative S4 Excavation, Biopile, Backfill (Soils)


-~~--- -------FTA (I

Hangar ;~ I ::;2 (I +--

Hang,1f ](1;1 I 124 [I I

rfallga1" 14 1 112 (I

f-iarii.1J f:; !:;S (I

A.DSA LL!7_~. __ J 1_ .. _---- ------

-----

:;Sw :;2

124

1 12 :;s

_____ IF_

Timet,)

Clmnup (I'c'~r'i I

L ___

t..ltl'rn<ltiVt' ~ Clln~bts of l'XCil vatil1,~ contilminiltpd ~hilll()w soib, trilnsportin~ them to iln (In-baSI' biopile cell, trcatingthesoibuntil accl'ptilhk kvdsan' reached, ,md b;lCkfJlh1\~ the c'xcavatiot1S '.\lith treated soil or ()tlwr,'ll'an b, IITOW matl'riill ff( 1m,)l) bil~('. At tIll' biopile cPl!, Sl l) I 'i V\ (JIdd bl' moundl'd (I ver ,1 sl'rils of pl'rfor a ted pipes (!l1 tppof an impermeable liner. Airdrawn through tl1(' ll\ ('rlymg pill' would enhanc(' ;ICf( ,bic dl'gr,ldation \Jf (lrganic c('ntaminants and strip the volati1l' orgilnic comp()unds iVOCs) from till' sOlh. S()il from thl' pile IV(luld bl' <';,lmpll'd ppriodicillly tn dl'tl'rmiIll' tIll' prngrl's; of thl' remediation. Onc(' I he s\lll is cle,ln, it can he llSI'd k'f h1Ckfilllln b<lse

Alternative S5 In PlacE' Bioventing (Soils)

I - -- .- - ~S;-C(1'it;(ill~ll~~~I~l~t~~) I -'- -~-~- -------

I I'n"cnt

II!~ Sl~CI~~"-'-~ rC<lPIt<l]-,. ~l1rllrd.!.._ \,y~,~t~ __ FT.\ 9() 4" 1 ']

Hdng,lr?) NA NA . 1\A HdnglllO,l 4:1 1X '(,

H'lngll 1t N;\ NA '\.A

I

H'lI1g'l1 1; 42 II ;J ADS/, 4:1 . I )2 N,\ = r-.;,It ,11'pih'able.

-- ----- -- ---- - -- --- --.. --- ---- -

Tllntchl

Clmnup l Vl'ilr' I

NA 2 NA

2

OU 4 Proposed Plan

In bioventing, air is injected into the soils to incTl'as(' thl' oxygen content. By increasing the oxygen content of the soil gas, bioventing increases aerobic dl'grad<l tion of the contaminants by naturally occurring micro organisms. Unlikl' Alternatives 53 and 54, this altem<l tive was develllped to address only deep soil c(lntilmi nation. Bioventing is considered highly efft'ctive tw deep spil contamination. In addition, Altl'rn<ltiVl' '.:;.r; calls for the land use restrictions and soil m()nitmin~: described in Altl'rnative 52.

EVALUATION OF ALTERNATIVES AND PREFERRED ALTERNATIVES

The pretcITl'd alternatives for OU 4 were 'il'll',ted 1111

the basi,; (If nine remedial alternati ve evaluati"n crill' ria found in the National Contingency Plan. Tahle 4 page 11, Identifies and defines these criteria. /\ dl' tailed compilratiVl' analysis of all of the altl'rn<ltivc', with respccllo these nine criteria is pn'sl'ntl'd tn'low The nincaltl'rnatives consider site-specific fach1rs such as the exioting site risk and levels of cont<lmination, a~ wl'll as milTl' altl'rn<ltivl'-specific factors Sllch as ,II

a Iternil ti \'l"" lnng-term effecti veness and impk mcntabilit\ .

Contamillationat au 4 falls into three basic C<ltl'g()ril ':"

• • •

Croundwater; 5h<lllow soib; <llld Deep ~()ib.

The prpferred alterniltive for groundwater at all sourn areas is Altl'rnative C2 (institutional controls with intrinsic fl'ml'diatillll). Altemativlc' S2 (institlltionili controls with intrinsic femediation) is also the pre krred ,lltcrn<ltiv(' for ~hallow soils at all th" SllUTC!

areas, and for the decp soils at Hangilr 'IS. A Itcma ti VI

55 (bioventing) is the preferred alternative for the de"'f' soils at th(' FT A, AD5A, and Hangar 11. Alternativl' 'i'; was Ch05l'l1 beCause these three area,; could (lcl a> d

fulure smrrc" of ~r()lIndwater contamination and thu' pose a human health and environmental risk,'llw prl' ferred alt('rnatives arl' summarized in Table 5 ('11 pa~l'

12. FiguT(' ), pagl' 13, providl's an illustration of t ll('

prl'fl'rrL'd altl'mativl'o;, The overall presl'nt worth nl~r (If these prdcrfl'd alternatives is $9hH,OOO.

au 4 Proposed Plan

Comparative Analysis of Alternatives

The basis for comparing the alternatives is th('ir ability to meet the criteria in cleaning up the areas thatrequire remediation. The discussion below compares how each of the five alternatives meets the nme National Contingency Plan criteria.

Protection of Human Health and the Environment. For groundwater, Alternative G3 (air sparging) would provide the greatest protection of human health and the l'nvironment because groundwater would be actively treated to acceptable levels. Contaminants would be strIpped from the groundwater. Alternati ve G4 (in place bioremediation) is ~1ightly ll~~s protective because it may not be effective for treating the solvents


that are present at the ITA and Hangar 15. Alternative G2 (institutional controls with intrinsic remediation) IS

slightly less protective than Alternative G3. Alternative Gl (no action) is the least protective, since then' would be no institutional controls and no monitoring, so that future contact with groundwater contaminanb would still be possible.

For shallow soils, Alternatives 53 (excavation and recycling) and 54 (excavation and biopiling) would equally provide the greatest protection of human heal Ih and the envi ronment.ln both cases, contamina ted Sl Ii b would be removed (thereby eliminating risks), bllt some contaminants would be released to the atmo sphere during exca vation. Al ternati ve 52 (insti tu tio n.11 controb with intrinsic remediation) would also 111'

--------------------------.----------------------------------------------------------------------Table 4. Remedial Alternative Evaluation Criteria

~------------------------r-------------------------------------------------------------Evaluation Criterion Definition

Protection of human health and Protection of both human health and the environment through the elimination, the environment. reduction, or control of contaminated media.

r---- ----.---------- -----.. -------------Compliance with ARARs. Complies with applicable or relevant and appropriate requirements (ARARs)

sHch as laws ;md government rebl"ulations.

r·------- --r---------------------------------------------------------------Long-term effectiveness and Protection of human health and the environment after the remedial objective~ perrnanenl'e. i have been met, including adequacy and reliability of controls.

---- ----- "----------i-- - ----- "--------------.-.- . ,,-----Reduction in toxicity, mobility, : Treatment to reduce the toxiCity, mobility, and/ or volume of the contaminated or vulume through treatment. L media.

Sh(;;t=;~rmeffe(~venes~-----I P~~ectio~ of human health and the environment during construcb()n~n~j i llnplementabon. Degree of threat and the time period to achieve remedial acbt 111

I, obJectivE'S are also considered. ----- ---- ------------- ---f--- ---- ----------.-------------------------.. -.---------- -Implt~mentability. I The availability of materials and personnel, site features such as available span'

and topography, and impacts upon ongoing operations are considered. TIll' technical status of alternatives is also considered; theoretical technologies Wlth only limIted bench-scale evaluation are considered less Implementable than

Cost

I I fully proven processes.

---------~--- ----------------- ----,,- ------------_ .. _-! Costs include design, construction, startup, monitoring, and maintenann.' I Accuracy to within -30% and +S()'1c ..

-5ta~~~-~~-tanCl-!. ------- -I~~dicate~ whether, on the basis of ib review of the Proposed Plan and supporting I documellts, the 5tateconcurs with, opposes, or has no comment on the preferTf..:'d I alternative.

~();;mu~~ y acceptance. ..--.. ---+~~e comnmni ty' s preferences will be assessed in the Record of Decision follo~ i ing a revit'w of public comments received on the Proposed Plan and supporting i documents.

~-----------------------~

11

Elmendorf Afr Force Base

protecti ve of human health, using land use restrictions to prohibit contact with or ingestion of the contaminated shallow soils. Alternative 51 (no action) is the least protective, since there would be unre:ltricted access to contaminated soils.

For deep soils, Alternative S5 (blOventing) would provide the greatest protection of human health and the environment because contaminants would be broken down in place, thereby eliminating risks. 50me contaminants would be released to the atmosphere. With Alternative 52, land use restrictions would prohibit excavation of contaminated soil, minimizing the risk to humans or the environment. Alternative 51 is the least protective, since there would be no restrictions on excavation of contaminated soil.

Compliance with ARARs. For groundwater, Alternatives C3 and G4 will be aggressive treatment and will comply with cleanup standards. AlternativeC2 would also comply with applicable cleanup standards, only the time to achieve these leveb would be increased, Alternative Gl would fail to meet the requirements, sinc(' there would be no way to confirm any reduction in contaminant levels.

Fnr shallnw soils, Alternatives S3 and 54 would have the highest probability of complying with all requirements. Alternative 52 would meet the standards over time. Alternative 51 would fail to meet the requirements, sinc(' there would be no way to confirm any reduction in contaminant levels.

au 4 Proposed Plan

For deep soils, Alternative 55, as an active treatment, will comply with all requirements. Alternative 52 would meet the standards over time, except possibly for some hydrocarbons at the AD5A or solvents at the Ff A. Alternative 51 would fail to meet the requirement~, since there would be no way to confirm any reduction in contaminant levels.

Long-Term Effectiveness and Permanence. For groundwater, Alternatives G3 and G4, as aggressive treatments, would reduce risks by eliminating contaminrttion. Alternative G2 would reduce contamination permanently, but over a longer period of time, therefore requiring additional long-term management. Alterndtive Gl would not prohibit future groundwater contact, and there would be no long-term management

For shallow soils, Alternatives 53 and 54 would reduce risks by removing contaminated soil and breaking down contaminants. No long-term management would be needed after the contaminated soils are removed. Alternati ve 52 would reduce risks by prohibiting contact or ingestion of the contaminated medium, but would require lung-term management (land use n'strictiom, five-yearreview ,etc.). Alternative 51 would not decrease risks and there would be no long-term management.

Table 5. Preferred Alternatives for au 4

Soils _.

Source Area Groundwater (plumes) Shallow Deep --~- -

ITA G2-ICIR* 52-ICIR S5-Bioventing f------~-- -~~ -

Hangars 8/10 (plumes only) G2-[c:rR Not applicable Not applicable Hangar 8 (soils only) Nut applicable 52-ICIR Not applicable f-.--.-~-- . ---~~ ---_.

Hangar 11 (plumes only) C2--[ClR Not applicable Not applicable Hangars 10/11 (soils only) Not applicable 55-Bioventing 55-Bioventing f--~--~--' .--~~----~~-- -

Hangar '[4 C2-[CIR 52-ICIR Not applicable ._----- ------

Hangar'15 G2-1CIR 52-ICIR 52-ICIR f-------

ADSA i

Not applicable 52-ICIR S5-Bioventing I ---~.

'Iern. = InstItutional controls with intrinsic remediation_

12

au 4 Proposed Plan

WEST Institutional Controls

Bioventing


EAST

Bioventing

-, !

Monitorinf~ and IntrinsIc Remediation for Groundwater and

Soils

~~ ~ Monitoring and Intrinsic Remediation

J==:;:::;:, for Groundwater and

Figure 3. Preferred Alternatir1es

FOf dl'cp soils, Altemativl' 55 vvould n'duce the rbks through tI'cCitment. No l!lng-tprm mCinagement would he m'l'ded. Altl'rnCiti vc S2 would red un' risk~ through land the restrictions Clnd long-term managempnt. AIternati ve 51 would not dl'cn'ilsc ri"k~ ;md then' would be no Itlllg-ll'rm manaw'ml·nt.

Reduction ill Toxicity, Mo/lildy, or Volume Through Treatment. For groundwClh·I'. Alternatives G4 and GJ would proVIde the greatest red1lction through tr(,Cltmen!. ,\Iternative G2 would pfm'ide feduction in toxicity ,llld volume; howl'veT, the !irnl' to achll'vl' the rt'duchm is longer and this ,lltl'rnCitivI' doL'c not involve IreCltrnl'nt. Mobility would not 1ll' reduced. AItcrnCitive G1 provides no trl'<ltrnent and no monitoring, so any ctfectivl' feduction could not bf'l'v,lIuatl'd.

For ~h,!II()w "oils, Altl'rnCltivl'c> S.l and S4 wlllJ!d pmvidl' ('qual [( ,ntaminant rl'duction thr(lugh eXl avation and tn·atml'nt. With Altl'rnativ(' .,2, the toxicity and volum,' of omtaminanb wllllid be n'ducl'd through intrinSIc reml'diation, but mobililv '.,-,ould nllt be f['-

13

duced. Abo, this alternative docs not include trc.l1 ment. Altl'rnativl' Sl provides no trl'atment .md 11<'

monitoring, so any effective reduction could not 111' evaluated.

For del'p soib, Alternative 55 would reduce the tox ic ity and voluml' of contaminated soils through biodq.?,· radation .1I1d volatilization. Alternative 52 d()l'~ I'(li

involvl' treatment, but would slowly redllCl' tIll' tClXI( ity ilnd vlllume of contaminCints intrinsicCill y. Alten Ii!· live 51 provides no treatment and no monitoring, ~., any effectivc' feduction could not lw evaluated.

Short-Term Effectiveness, For gmundwatl'r, Altenla· live G2 wou Id have no significant short-term ric-k sino' implementation would re~ult in im;i~ificant ('XJ'll sure. Altl'rndtiVl'S C3 and C4, requiring son1(' C( n structi()n dllring implementation, would havl' mini mum risk~. Similar workef protection m('d~ur('~ Wl lt 1. i be takl'n for C2, GJ, and C4. Alternative G1 wl)].:J.I present nc) additinnill short-term risks, sincl' t1wrl' is n., cunstnlction associated with this altl'rnativl'.

Elmendo/1 Air Force Base

For shallow soils, Alternat1w S2 is the most protective over the short term, sinn' implementation would re~Illt in insi)-,'11ificant eXp()~llrl·. Altl'rnativl's '13 and S4 were determined to be equally effective owr the short term. The~(' two alternativl's would pose :;ome low risks to lV(lrkers and the communi tv becau:·.l' of excavation, hallling, and treatment. Alternative S1 would rrc~l'nt no ,idditional short-h'nn ri"k~ since there is no constTIlct1on associated with this alternati\'\'.

Fm depp soils, Alternatives S2and S5 were dl'termined to be equally protective over the short term. With both alternatlw~, implementation would fl'stlltin minimal exposure (If workers to contamination. Altemativl' 51 rl'qU1re~ no implementation, and thereforl', VIi ould rreSl'nt no addi tional short-term risks.

Implementability. For groundwater, Alternativl' G1 would not require "implementation" since there is no action. Alt('rnative G2 could be implemented edsily, ~incl' it l'nt.lils only the installation of long-tl'rm monitoring weiI-;. Alternativl's (;3 and C4 might interfere with some base opcrations near thL' hangar", emd thl' systems w,)uld rpquire mon' substantial maintenance ,md lpl'ra ti 0115. With Alternative Gi, enId wedther ma\' cau se ,lboveground pirt'S to freL';~L', willkr mainlen, met' is problematic, Clnd the f('quirL'Cl l"luipml'nt w01lld n'tl'lire o,ignificdnt ~p,ICt'

For :-,hclilow soils, Alternative Sl w(luld TI'quirp no impl(!mpntation. Alternative 52 could bp impleml'nted the most l'.lSily, similar to groundwater. Only certain acCl"'S fl'strictions and monitoring would be reqtlired. With both AlternCltives 53 and S4, l'xcavati,m would disturb ba,p operat1ons near tfll' hangars Permits, ('qUl pmenl. specialists, and spacl' for On-hlS(' treatment or arrangeml'nt for ()ff-ba~e disposal would be req1l1red.

For deep soils, A Itprna t1ve 51 would require no implementation. Alternative 52 could be impleml'nted the most easily, similar to shallow soils. Only certain acc('ss restrictions and monitoring wlltild hl' required. Altl'rniltiV\' S,'i muld interfl'rc' with ,onw h<ls(' opprations near the hangars, and would r('quirt· permits, equipment, and specialist".

Cost. For groundwater, Altl'rnatiVl's C4 ($H.X million) and C:l ($3.7 million) cost many more times than AlternatiVl' G2 ($0.43 milli(lI1). AllL'rnative Gl has no cost.

14

au 4 Proposed Plan

For all soils, Alternatives 53 ($3,2 million) and S4 ($2.2 million) cost many more times than AlternativL' ",0;

($0.34 million--<iecp soils only) and Altl'mativc ".2 ($0.34 million). Alternative 51 has no cost.

State A.cceptance, The State concurs with till' prdernd alternatives identified in this Proposed Plan.

Community A.cceptance. Community Clcceptance will he ('valuated during the public comment perilld in it responsivl' summary as part of the ROD on th,' basis of comments on this Proposed Plan.

Rationale for Selecting Preferred Alternatives

Alternativ(' C2 is the preferred alternative for gfllllndwater at all of the source areas with contamin,ltl'd b'TlJundwatcr. After a thorough review of tlw vari(lll~ alternatives, considering the groundwclter T1sks, cleanup timcs, and altemati ve costs, it was ddermllll·d that proteCtion of the environment could be achil'vl'd without aggressive treatmt'nts, Institutional comn,)~ with intrinsic remediation for groundwater provic('~ protection of human health and theenvimnment 'A it h(lut the high C()~t and technical problc'ms a<'SllCi.lt,d with active ~roundwater tfl'atment alternatives.

Modl'ling results show that groundwater C(lllt.lmin,l· tion a te'l] 4 will not migrate Ilff site. With A I tcrna ti \ l' G2, USI~ of the shallow groundwater aquifl'r \, <l

water supplv will be prohihited by access Tl"trictil'n~ during the pl~riod of time it takes for natural proCl'S'I'~ to remediatl' the water. MonitOring Willl'll;ure tl,.lt contaminated groundwater does not migratl' lx'yond access-controlkd areas. Thp long-term monitoring a Ild the five-ymr review procpss associated with I his alb-r· na live wi 11 provide a sa fety net to protect (ltlll'r a re, I,. , )1

tlw Bas(' or other receptors from off·site migration III OU 4 gn Hmd wa ter contaminants. Institutillnal 1'( Ill

trois wit h intrinsic remediation for ground watn i:, thl most c<1sily implemented ilnd cost-cffectivl' altcn,,,tive that will meet the requirements at (\l('h 1)1 the sOtlrc(' aTl'a~.

Alternati ve '12 is the preferred alternati V(' for sha 11(1 W

soils at all "Durce areas where low leveJ:.; of tar and asphalt hy-products are tht, most common contdminants_ lnsti hI tional controls with intrinsic rernl'dia ti· l]1

fm thl' ~haJ]ow soils provides protl'ction of hUJnlll health and the environment without till' high II'-t uncl'rtaintil'~, and technical problems of m( lTl: ilggr, ',sive tre,Hml'nts. With Alternative 52, land ll:-l' restrll'tions on thl' Base would prohibit acc('ss and Ji,tllf'-

OU 4 Proposed Plan

banel' within the source areas whill' natural processes remediate the soil. These restrictions would be easy to implement sinn' this area i~ in an active airfield. The progress of intrinsic remediation would bl' tracked through annual monitoring. This alternative achieves the ohjectiv('s at the most re,l~ionabk cost.

For d(~ep soils, Alternative S5 is the prderred alternative for the fT A, the ADSA, and Hang,u 10/ 11 source area~_ This alternative was chosen fur the PTA and Hang.u 10/11 beciluse biovl'nting ~,hould act qUickly tpc!ean up the deep soils, which could actas a contmuing ~(lurce tor groundwater contamination ilt these lpciltions. Alternative 55 wa, chosen for the ADSA because the high concentrations of hvdrocarhons will degrade m(lre quickly with active rt'mcdiation. 'TI1is alteTlutive I~ a very effectivl' altl'rnative at a rl'iati vely low C(lst for removing the fuds and fuel residues from these deep ~()ils.

Alternative.,2 is the preferred alternati Vl' for the Hangar 15 source area, where, like the shallow soils, most of the contaminants are low-level tar and asphalt byproducts. Because of the types of the contaminants prespnt, they are not likely to migrate into the groundwater in the future. '111is alternative will meet the requiremenh and is also the most cost effective. Deep soil contamimtion is not presl'nt ilt the Hangar H ,md 14 sou Tce rlrcas.

The preferrl'd alternatives were chosen on the basis that assumptions behind the hillman health risk calculation~ are very conservative. HOWl'Vl'r, no alternative will be selected until after the public comment period. I t is ex tremel y unlikely thatfu ture reOiidc'n ts would use contaminated water from the upper aquifer fllr drinking and showering. Upper aquifer wells are not being used ft lr any purpose, and they are not l'xpectl'd to be used in the tuture. It is also highlv unlikely that residl'ncl'~ would be constructl'u in thest.' areas, since tllPy an, adjacent to hangars and runway~. In summary. the preferred altemati ws are expected to provide the be"t balance of tradl'offs among nil of the possibil' alternatives with rt'spect to the National Contingency Plan criteria. Therefore, the USAF, EPA, and ADEC lil'lie\'e the preferred alternatives would:

• Protect human health and the environment; • Comply with ARARs; • Be cost effective; and

15


• Use permanent solutions and alternati v(' b'chnologies or resource recovery to the maximum extent practicable.


You are encouraged to provide comments on any of the alternatives during the public comment period. You can make your comments either in writing or .1t the public meetings. The public comment period IS

from 11 April 1995 to 12 May 1995

The USAF will prepare a written response to all signiticant comments, criticisms, and new data submitted to

this Proposed Plan. A summary of these responses WIll

accompany the ROD forOU 4, which will be availabll' in the ad ministrative record at the Information Repll~itori('~.

Public Meetings

A public meeting to discuss the Proposed Plan, answ('r questiom, and receive public comments will be held from 7:0() to Y:OO p.m. on Wednesday, 10 Mav 1995 at the University of Alaska Anchorage, Busines~ Educa tion Building, Room 207.

Places to Find Information Repositories (relevant documents).

• Bureau of Land Management Alaska Resources Library 222 West 7th A venue #36 Federal Building, First Floor Anchorage, Alaska 99513

Hours: Mon-Fri: 8:00 a.m.-5:00 p.m.

• University of Alaska at Anchorage Consortium Library Reserve Desk 3211 Providence Road Anchorage, Alaska 9lJ5lJH (907) 786-1871

Hours: Mon-Th: 7:30 a.m.-1O:00 p.m. Fri: 7:30 a.m.-6:00 p.m. Sat: 11):00 a.m.-6:00 p.m. Sun: Noon-6:00 p.m.

These hollr.-i will vary according to the academic calend.1r


Contact for Questions

Community Relation~ Coordinator 1\1r. M.lrk Davidson fuhlic Affair" Office, 1WG / r A n'J2( I 1 :2th Street !·I m('n,jorf Air Forcl' Ba::;e, Ala~kil Y9S0il-253() (qtl7) 5')2-5755

ACRO"lYMS

ACM: A Ia-;ka Cleanup Matrix for non·undergrtlllnd ,wrage tank contiUninatcd soil

AIJEC: Alaska Department of Envimnrnental Conservation ADSA: Asphalt Drum Storage Area

AFB: Air !·tlrce Base

ARARs: Apphcahle or Relevant ~U1d Appropriate RVljuircmcnts

UTEX: Ikn/ene, Toluene, Ethylhenlelw, and Xylenes

CERCLA: Comprehensive EnvlfonmenUil Respt lIlse,Compensation, and Liahility A(t (also known as S lIperfund).

EPA: lJ. S Environmental ProteUlon Agency

.;FA: Fl:Jeral Facility Agreelm:nt

J<TA: Fire Training An:a

HI: Hazard Index

ICIR: Institutional COlllrnIs with IntrinSIc Remediation

OU: Ope"rahle Unit

PClh: Plllvchlorinated Biphenyls

Rill'S: Rellledial Investigalilln!Fe;L\ihilily Study

RME: R,"a.\onable Maximum Exposufl'

ROD: Recurd of Decision

SIJW A: Safe Drinking Water Act

16

au 4 Proposed Plan

TCE: Trichloroethylene

lICLs: Upper Confidence Limits

lJSAF: U. S. Air Force

VOCs: Volatile Organic Compounds

GLOSSARY (W TERMS

Air Sparging: A form of treatment in which ilir I~

injected into groundwater. The bubbling air ('nabk~ the contaminants in ground wa ter to become .Iirborm', or volatJlize

Aquifer: An underground body of water that occu r~ '\ t vilrious depths.

ARARs: LilWS ,ind regulations that establish c1eanllp levels for sites with contilmination,

Benzene: A carcinogenic compound typically as~() 1-

ated with fuels such as gasoline, kerosene, diesel, -llld

jd fu!'!. Along with l'thylbt.'nzene, toluene, and )( \lenes·--a\:;o dssocidted with fuc\:;--benzl'I1l' make, lip

the contaminants known by the acronym BTEX.

Biopiling Treatment: A form of treatml'nt that (11-

hances natural degradation processes to reduce and eliminate contamination in soil. Soil is tranSpl Jrtl'd tl) il facility where air and nutrients are added into till' contaminatt'd material, increasing microbial popt! .1-

tions. The organisms then degrade the contamin'lIlh.

Bioventing Treatment: A form of treiltmpnt that l'llhances nCltural degradation processes in the g:round 1\,

treat soil contamination. Air and nutrients an' injeckd into welb within areas of contaminCltion to <lCCder,il('

degrada tion by microorganisms. Unlike biopiling, s· Iii undergol11g billVl'nting is not l'XGWilted.

Deep soils: bor the remedial actions plilnIwd for OL ·l, deep soils arl' thosp found ilt depths greater than 5 ted. Contamination of deep soils has been found ,It Hang,lr 10/11 and tIlt' FTA and ADSA.

(Continued orr Pag!' 19)

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

I

au 4 Proposed Plan Elmendorf AIr Force Base

USE THIS SPACE TO WRITE YOUR COMMENTS Your comments and suggestions about the remedial alternatives discussed in this Proposed Plan are important to the Air Force. Comments that the public provide are valuable in helping the agencies select a final remedy for OU 4.

You may use the space below to prepare your comments. When you are finished, please fold and mail. A return address has been provided on the back of this page for your convenience. Comments must be postmarked by 12 May 1995. If you have questions about the comment period, please contact Mr. Mark Davidson at (907) 552-5755.

-----.. -----

.----.------

Name

Address ________ _

City

State Z lp ______ ... __ _

PUBLIC

COMMENT

Name ________ _

Address City _________________________ _

State __________ Zip _______________ _

Mr. Mark Davidson 3 WG/PA (1920 12th Street Elmendorf AFB, AK 99506-2530

SHEET

Fold along dashed lines. staple. and mail.

rg-PLACE STAMP HERF~

OU 4 Proposed Plan

GLOSSARY (Continued from Page 16)

Ecological Risk Assessment: A study of thl' risks to plant" and clnimals that can be attributed to sill' contamination.

Grollndwater Table: Thl' groundwater surface in undergmund rock or soil.

Human Health Risk Assessment: A ~tlldy of the risks to human hl'alth that can be attributed to site contamin,lti(l]I. The ,tudy can be di vided into cancer risks and nl)J1(dnCl'r risks.

Institutional Controls: Physical or legal barrIers such d~ fences cllld deed restricti()n~ that limit acCl'S~ to C()Jltaminall'd arms. Thl'Y can be a pplied in a \,Iriety of f(lrm~ to gr(lundwater and ~(Iib.

IIrtrillsic Remediation: Thl' pron:'ss whereby bacteria and other micro()rganism~ that occur natur,llly are allownl to h'ed on the contaminanb found ill the soil and the groundwater and, ()Vl~r tim!', reduce tIll' ('ontamin.lIlt leveb.

mglkg: Milligrams of contaminant pl·r kil()~am. of soil; used ttl measure degn'e of :-'011 l'ontamlllatlOn (parh rl'r million). (This tc'rm a pp!'il rs only in Tabll'l.)

Monitoring: Measurements (If soib ,mel groundwater l(udlit\ to dderminc the extent ot c(lnt.lmin'ltllln ilnd tl1l' dl'~n'l' ttl which it is cll'aned lip.

National COlltingency Plan: This federal plan impkml2nt:-; thl' rl'<]uirements of CERe LA. It provides the organization structure and pn )ct'durl'~ for addressing tcder,l' Supnfund ~ites.

Operaille Unit: An area within a sitl> that is composed of simllar contamination and b similarly managed to achieVl' c1panup.

lLJ


PCBs (PO lyc11 lorinated Biphenyls): A group l)f fl'ld kd compounds typically used in electTical tran~forml'l '.

Plume: An area of groundwatl'r that is belil'\'ed t,) [1('

contaminated.

Proposed Plan: A documl'nt prepared to inform tlw public about alternatives that wen' considl'red fllr cleaning up a contaminated site and which altcrna ti Vl' or alternatives havl' be'en identifit'd as tlK' prdl'ITI'd alternativds}. The documl'nt encOllrages pllblic (l1I!'

ment on all alternativl's.

Remedial Action: Actions taken to l'iiminalt', r('dlll l', or control the hazards posed by a ~;itl'.

lUIFS: Two interrelated CERCLA (see Superfund) studies. The Rl is conducted to identify the typl''-, amounts, and locations of contamination ata iacilit\!. It also eva.luates possible risk to the public and environment from l'xposure to contamination. Thl' FS identifies, scre('n~, and evaluates different altl'rn.lti\'l's f"r cleaning lip contamination.

Shallow soils: For the remedial actions planned for OU 4, shallow soils are those found at depths less thall 5 feet. CClIltamination of shallow soils has bl'vn f(]l Illi

at each of thl' DU 4 source areas.

Superfund Program: TIll' federa.l hazard(]u" wastl' cleanup program administered by the Enviwnrnl'I,t,Ji Protection A~ency. Its formal title is the ComprdwJ' ~ive Environmental Response, Compensatl{)n, an.1 Liability Act (CERCLA).

TCE: Trichloroethylene. A volatile organic compounJ used as a cJcoaning solvent.

IlgIL: Micrograms of contaminant per Ii It'r (If wate!" used to measure degree of groundwater contamilld tion (parts per billion). (This term appear~ (lnly in

Table 1.)


PUBLIC MEETING

A public: meeting will be held at the University of Alaska Anchorage

Business Education Building Room 207

on 10 May 1995 (Wednesday) from 7:00 to 9:00 p.m.

ELMENDORF AIR FORCE BASE 3 weiPA ()920 12th Stn't't Elmendorf AFB .. ~K 995[)h-2530

Attn: Mr. Mark Davidson

JENNIFER ROBERTS ALASKA DEPARTMENT OF ENVIRONMENT AL CONSER VA TION 3601 C STREET STE 322 ANCHORAGE AK 99503

OU 4 Proposed Plan

BULK RATE US POSTAS'

PAID PERMIT NO. 6Ei9 Anchorage, ~v

R ECEIVE l~ APR 1 1 1995

DEPARl¥ENT OF ENYfRONMENTAI. CONS~HVAT!C

seRO

UNITED STATES AIR FORCE ELMENDORF AIR FORCE BASE, ALASKA

ENVIRONMENTAL RESTORATION PROGRAM

RECORD OF DECISION OPERABLE UNIT 4

FINAL

SEPTEMBER 1995

"" ," . • = •

• = :,:,,!.=. "

UNITED STATES AIR FORCE ELMENDORF AIR FORCE BASE, ALASKA

ENVIRONMENTAL RESTORATION PROGRAM

RECORD OF DECISION OPERABLE UNIT 4

FINAL

SEPTEMBER 1995 DI='P;:··'Mr::r>-,1T OC'

EtMRONMEtIi"fp:L C01~SE!):ATk

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