Attachment 1 EE/CA Approval Memorandum

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~11i~tRJ . I '3,~. 3

U.S. ENVIRONMENTAL PROTECTION AGENCY REGION I

J.F.K. FEDERAL BUILDING, Boston, MA 02203

MEMORANDUM

DATE:

SUBJ:

FROM:

TO:

THRO:

Barkhamsted-New Hartford Landfill Superfund Site - Approval Memorandum to Perform an Engineering Evaluation/Cost Analysis for a Non-Time Critical Removal Action

Eric van Gestel, Remedial Project Manager LeAnn Walls, Assistant Regional Counsel

John DeVillars Regional Administrator

Frank Ciavattieri, Acting Director k~//¥ ~ Waste Management Division ~L

Edward Conley, Director ~~/'!'f'!-Environrnental Services Division

Pam Hill ,-J ,·,~ Deputy Regional counsel

This memorandum recommends that you authorize the preparation of an engineering evaluation/cost analysis (EE/CA) for a non-time critical removal action at the Barkhamsted-New Hartford Landfill Superfund Site (the Site). The EE/CA will evaluate cleanup alternatives for source control measures (Phase 1) at this Site. Consistent with EPA guidance documents concerning SACM actions, the Regional Decision Team concurred with the decision to proceed with an EE/CA at a meeting on January 27, 1994.

This memorandum does not constitute the Agency's final decision concerning the selection of response actions at the Site. The Superfund decisionmaking process for this Site will proceed as follows:

Phase 1 (Source Control):

ROT concurs that Site conditions warrant a non-time critical removal action (NTCRA) . Initiate an EE/CA to evaluate NTCRA options. Finalize EE/CA Report and conduct a 30-day comment period. Select the NTCRA in an Action Memorandum.

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Phase 2 (Management of Migration):

Finalize the RI/FS and conduct the Proposed Plan comment period. Select a final remedial action in a Record of Decision (ROD).

I. site Description and History

The Barkhamsted-New Hartford Landfill Superfund Site is located within the towns of Barkhamsted and New Hartford, Connecticut (see Attachment 1). The landfill is located on a 98 acre parcel of land and is owned and operated by the Administrative Board of the Regional Refuse Disposal District #1 (RRDD#l). It is bounded by the RRDD#l boundary to the north, an unnamed brook to the west, a landfill access road to the east, and a drainage ditch constructed along the Barkhamsted/New Hartford town line to the south (see Attachment 2). A brief chronology of significant events related to the Site is detailed below:

1974

1974-1988

1980

1981

1987

1988-1993

1989

1991

1993

The Site began operations as a municipal landfill.

Site received residential, commercial and industrial wastes.

A Connecticut Department of Environmental Protection (CTDEP} Hazardous Waste Materials Unit Site inspection revealed the presence of metals, hydrocarbons, benzene, hexane, pentane and toluene at the Site.

EPA performed a preliminary assessment of the Site.

EPA conducted a Site investigation which revealed the presence of elevated levels of xylene, toluene, 1,1-dichloroethane, 4-rnethyl-2-pentanone, and vinyl chloride in groundwater.

Landfill used only for the disposal of bulky and non-processible wastes.

EPA listed the Site on the National Priorities List.

site PRP Group agreed to conduct the RI/FS under EPA oversight.

A draft Initial Site Characterization Report was submitted to EPA.

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1994 A draft Remedial Investigation Report was submitted to EPA.

II. Nature and Extent ot contamination

The source area for contamination migrating from the Site is contained within the 10.2 acre disposal area of the landfill. Accordingly, EPA has determined that the entire landfill should be deemed one source area for purposes of the RI/FS.

During Phase IA of the Remedial Investigation, groundwater, surface water, soil, sediment and air media were each investigated for the presence of Site contaminants. The following data is derived from those investigations. All listed compounds are "hazardous substances" as defined by CERCLA § 101(14) and 40 C.F.R. § 300.5:

Groundwater

Compound

arsenic beryllium DEHP lead 4-methylphenol· vinyl chloride manganese

highest cone. (mg/l)

7.4E-04 6.SE-04 1. 6E-03

.90 above cutoff na

6.SE-04

0.04 0.01

10.00 0.20

45.00 0.03

28.00 haz. quot.: 153.4

All data is expressed in parts per million (ppm).

III. Basis for EE/CA and Non-Time Critical Removal Action

Section 300.415(b) (2) of the National Contingency Plan (NCP) lists a number of factors for EPA to consider in determining whether a removal acti~n is appropriate, including:

(i) Actual or potential exposure to nearby human populations, animals, or the food chain from hazardous substances or pollutants or contaminants;

(ii) Actual or potential contamination of drinking water supplies or sensitive ecosystems;

(iv) High levels of hazardous substances or pollutants or contaminants in soils largely at or near the surface, that may migrate; (and]

(v) Weather conditions that may cause hazardous substances or pollutants or contaminants to migrate or be released (.]

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The site conditions discussed above (and as described in greater detail in the draft April 1994 Remedial Investigation Report) denonstrate that there is a continuing release and migration of hazardous substances from the source area at the landfill to groundwater. The release of hazardous substances to the groundwater has resulted in exceedances of federal and state drinking water standards, and thereby poses a potential threat to future residential users of the groundwater.

A preliminary risk screening of this Site was performed on September 13, 1994 using groundwater data derived from Phase IA of the Remedial Investigation. Attachment 3, prepared by an EPA risk assessor, provides a summary of the estimated risks for the Site. Based upon the ~cenario of ingestion of groundwater by a future residential user near the Site, the cancer risk at the Site is about 4Xl0-3 and the hazard index is about 430. The risk is primarily due to the presence of vinyl chloride (cancer risk = 7xl0-4) and 4-methylphenol (hazard quotient of 250). The risk from vinyl chloride alone exceeds lxl0-4 and 4-methylphenol's hazard quotient is about 250. The highest lead concentration in groundwater is approximately 200 parts per billion (ppb) (the EPA action level for lead is 15 ppb) . Ingesting this concentration of lead in drinking water may result in blood leads above 10 micrograms per deciliter (the EPA cutoff) for 90% of exposed children.

Consideration was also given to EPA's "Presumptive Remedy for CERCLA Municipal Landfill Sites" (OSWER Dir. 9355.0-49FS, September 1993) (Attachment 4). This guidance supports the use of a streamlined risk evaluation which primarily focuses on the groundwater pathway and does not attempt to quantify all pathways (including direct contact with soil or releases of hazardous substances into the air) . The presumptive remedy guidance states that once an unacceptable risk is identified through the groundwater pathway, other risks associated with soil and landfill gas can be assumed to exist using the conceptual site model developed for municipal landfills.

Consequently, based upon the NCP factors listed above, a potential threat exists to public health or welfare or the environment. A removal action is therefore appropriate to abate, prevent, minimize, stabilize, mitigate, or eliminate such threat(s). In particular, a removal action is necessary to control and contain the release of hazardous substances from the landfill at the Site through source control measures.

This removal action is designated as non-time critical because more than six months planning time is necessary before on-site activities must be initiated. Prior to the actual performance of a non-time critical removal action at this Site, section 300.415(b) (4) of the NCP requires that an engineering evaluation/cost analysis (EE/CA) be performed in order to weigh

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different response options.

IV. scope ot EE/CA

The purpose of the EE/CA will be to evaluate alternatives for source control response measures at the Site. The EE/CA will consider alternatives which will meet the following removal action objectives.

Landfill Area

a. Prevent, to the extent practicable, direct contact with and ingestion of soil/debris within the landfill and beneath the landfill;

b. prevent, to the extent practicable, the potential for water to infiltrate through the landfill debris mass;

c. control, to the extent practicable, surface water run off to minimize erosion;

d. control landfill gas so that methane gas does not present a fire or explosion hazard;

e. prevent, to the extent practicable, the inhalation of landfill gas containing hazardous substances, pollutants or contaminants to the extent necessary to meet state and federal standards;

f, prevent, to the extent practicable, the saturation of the landfill debris mass from upgradient groundwater;

g. prevent, to the extent practicable, the migration of contaminated groundwater and leachate beyond the boundary of compliance;

h. outline any data gaps which exist and review any pre-design activities necessary to complete design; and

i. prevent, to the extent practicable, the generation of landfill seeps and the migration of landfill impacted surface water into the Farmington River Valley watershed and other surrounding surface water bodies.

Pursuant to EPA guidance on EE/CAs, alternatives will be evaluated based upon effectiveness, implementability, cost, and compliance with ARARs. Further, alternatives which exceed $2 million will be evaluated to determine their consistency with future remedial actions to be taken at the Site.

In developing the range of alternatives to be evaluated in the EE/CA, EPA will consider section 300.415(d) of the NCP as well as

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relevant guidances (including the Presumptive Remedy Guidance). Section J00.415{d) of the NCP identifies various removal actions which may be appropriate in given situations, including:

(2) Drainage controls, for example, run-off or run-on diversion - where needed to reduce migration of hazardous substances . . . ;

(4) Capping of contaminated soils or sludges - where needed to reduce migration of hazardous substances or pollutants or contaminants into soil, ground or surface water, or air;

(6) Excavation, consolidation, or removal of highly contaminated soils from drainage or other areas - where such actions will reduce the spread of, or direct contact with, the contamination; (and]

(8) Containment, treatment, disposal, or incineration of hazardous materials - where needed to reduce the likelihood of human, animal, or food chain exposure(.]

These alternatives and others may be evaluated in the EE/CA.

v. Other Considerations

EPA will continue to examine the need for other response actions {e.g., remediation of the groundwater) through the ongoing RI/FS process. EPA will embody its decisions concerning other response actions in a ROD.

The current schedule is to have a ROD signed by the Spring 1995, with RD/RA negotiations completed by December 1995 and RA beginning in 1997. If a non-time critical removal action were initiated, an Action Memorandum could be issued in August 1994, consent order negotiations conducted in September 1994, and the removal action completed by the Fall 1995. A SACM early action could thus save at least two years in the implementation of the source control remedy.

The PRP Group that is currently performing the RI/FS has agreed to perform the EE/CA under the terms of the existing Administrative Consent Order. A Cost Recovery Administrative Agreement, approved in September 1992, provides for the reimbursement of EPA's oversight costs.

Finally, the State supports a SACM early action at the Site.

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VI. Recommendation

In light of the facts discussed above, the case team recommends. that you approve the initiation of an EE/CA for this Site.

Date 1

7

7

BARKHAMSTED PRP GROUP BARKHAMSTED NEW HARTFORD

LANDFILL SUPERFUND SI TE BARKHAMSTED, CONN.

PROJECT LOCATION PLAN T

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LEGEND

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To: Er~c Van Gestel From: ~ary Ballew

Attac~~ent 3

Re: Risks to hu::ian health a~ Barkhamstead, CT. Date:9/13/93

I screened all of the chemicals detected at the Barkhamstead site for potential toxicity. I eli~inated from further consideration several chem~cals with eitcer low toxicity or low concentration. I divided the remaining chemicals into those with carcinogenic risk (ie., those with a cancer class of A, B, or c --Table 1) or r.oncarcinogenic risk (ie., those with a Dor no classification of carcinogenicity--Table 2) . The only risks considered here were those for ingestion of groundwater.

The total risk of ca~cer from tte test wells is 3.8 x io·3 • This is outside E?A's acceptable risk ra~ge of 10"4 to io-~. Since this is a relatively new landfill i~ may account for the high concentrations of solvents at the s~te. I must ca~tion, however, that sone of the ~easurements are unusually high. The measurements have not been reviewed by a hydrologist and some sampling methods may bias weasurements o= metals and hydrophobic compounds. However, the risks of vinyl chloride exceed 1 x io·4 and the hazard quotient of 4-methylphe~ol is over 200 so these two chenicals alone exceed the risks at A~ich EPA usually cleans up a site. Both vinyl chloride and 4-~e':.hylphenol are relatively hydrophilic chemicals that are not subjec~ to possible biases from the hydrologic sampling (biases w~ic~ may be introduced by the high flow method) .

I investigated the risks from lead at the site~ This is among the higr.est risks at Barkharnstead. I ran the EPA lead model under the conservative assumption of children from 6 months to six years of age. Children in this age group are the most sensitive part of the population that may potentially be affected by the site. The highest concentration of lead in the water samples was about 0.2 mg/l and 90% of yo~~g children consuming this water may develop blood leads above ten micrograms per deciliter(ug/dl). Ten ug/dl is the scree~ing level for blood lead proposed by EPA and the Centers for Disease Control. Blood lead exceeding 10 ug/dl in children may signify the developmen~ of central nervous system da~age which n:y lead to a reduction in IQ.

Many of the chemicals at the site were toxic but not carcinogenic (Table 2). Also, for a fa~ potentially carcinogenic compounds, EPA does not have a cancer po~ency factor (also known as a slope factor). For t~ese chenica:s I calculated a hazard quotient and I su1~ed the hazard quotien~s for the sa~= toxic endpoint to get the hazard index. A hazard index or quotient exceeding one de~otes soNe haza~d and a r.=za~d index exceeding ten often leads to EPA taking an actio~ a~ a site. The hazard

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index for the immune system was 6.8, for the kidney was 8.2 and for t~e blood was 8.6. The hazard index for the central ne::::-vous syste~ exceeded 150 and for skin was a.bout 250. These last two indices exceed the index of 10 at which EPA usually takes an action. I must caution, however, that these two hazard indices are highly affected by the hazards of manganese and 4-methylphenol (cresol). Although both are toxic, there is less evidence linking their damage to one particular organ or system. For example, cresol leads to skin cancer in animals but may produce some other effect in humans.

In swnmary, the risks at the site from cancer exceed lxl0"4 and from toxicity exceed a hazard index of 10. EPA often takes an action at a site that exceeds this level of risk. Barkhamstead exceeds the levels of concern for six individual chemicals.

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T;1hlc 2. Risk screening.for Darkham~tcad site non-carcinogenic risk

compound foot-notes

~~c·n.~ 1;1~d;;1cnc - ··- == - i ac:cnapthcnc aoctonc aluminum :tntimony h:triurn hut:monc(2-)(MEK) co halt copper cy:rnidc dihutylphthalate ().()() l '1

0.11 ().(X)l.5

11 0.Xl I 0.27 1.21

HO at highest

cone

6~~i!.=o~ 2.7E-04

3.61!+00

2.5E+OO 1.9E.+OO l.4E+OO

6.0E-02 2.7E-04 l.7E-03

1.5E+OO 2.0E-03

4.21!+00 t.4E-03 3.0E-02 6.SE-04

1.51!+02 um-01 7.7E-01 8.9E-02 6.2E-01

2.6E-Ol 7.7E-03 6.0E-01 5.JE-01 1.5E+OO 3.21.!+00 3.7E-03 l.IE-01

cancer class

)) na D D na na D na D D D D D D na D D D na D D D Ill\

"" D na n:t D D D D D D D I)

D

organs or systems

· aflCctcd by oompound

livcr,kldncy

blood blood pressure bodyweight

skin

immune,blood

CNS

liver.kidney CNS,kidncy

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Footnotes for tables one and two:

a. MCL for chromium based on total chromium. b. MCL for nickel based on nickel salts. c. Load has an action level for water of 0.015mg/I. d. At this concentration of lead, 90% of children in the age group six months

to 6 years(which is the most sensitive population) will have blood leads above 10ug/I. This is the concentration that the CDC proposes as a screening level for blood lead in children.

o. nros for carbazolo, dichloroolhylono, di-n-octyl phthalato, 4-molhylphenol, MIBK, mercury, vanadium, and vinyl chloride based on heast.

f. HQ is hazard quotient. g. The cancer potency factor for 1,4-dlchlorobenzene Is from the ECAO on 9/9/93. h. na==not available i. - - - = con not calculate j. Concentrations of chemicals listed In tables one and two have not been reviewed by a hydrologist.

Some hydrologlc methods of sampling may overestimate concentrations of metals and hydrophobic compounds. k. nisks above 1 E-4 or hazard quotients above 1 .0 aro In bold.

I. method for calculating cancer risk: ((cone mg/I• 2 I/day* 350d/yr * 30yr)/[10yr • 365d/yr * 70kg BW))* CPF 1/(mg/kg/day)

m. method for calculating hazard quotient: ((cone mg/I• 2 I/day• 350 d/yr • 30 yr)/(30yr • 3G5d/yr * 70kg OW))/RfD mg/kg/day

n. hazard index for kidney= 8.2 hazard index for CNS== 156.6 hazard index for blood- 8.6 hazard index for skin- 249.5 hazard Index for Immune system 6.0

o. Although the HQ for manganese and 4-methylphenol are high, there is less support for linking their effects to specific organs (ie., CNS or skin).

p. total cancer risk= 3.BE-03

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~1 SEPA Presumptive Remedy for

CERCLA Municipal Landfill Sites

Office ol Emergen0' and Remeoral Response Hazaroous Site Control Oiv1s1on 5203G

OuiCK Reference Fact Sheet

Since Superfund's incepoon in 1980, the remedial :ind removal programs have fouod that certain categones of sit.es have sirrulu chuacteristics. such as cypes of coota.rrunanis present. types of disposal practices. or bow environmental media are affected. Based on information acqul!Cd from evaluating and cleaning up these sites. the Superfund program is underuking an initiative to develop presurnpuve remedies to accelerate future cleanups at these types of sitts. The presumpuve remedy approach is one 1001 of accelerauon within the Superiund Accelerated Cleanup ~todel (SACM).

Presumpuve remedies are preferred technologies for common categories of sites. based on historical patttms of remedy selecuon and EPA's scientific and engineering evaluation of performance data on 1echnology implemeotatioo. The ob1eco ve of the presumptive remedies initiative is to use the program's past ex.penence to scrcamline site i.nvesugatioo and speed up ~lection of cleanup actions. Over time presumptive remedies are expected to ensure consistency io remedy selecoon and reduce the cost and time required to clean up similar types of sires. Presumptive remedies are ex pee~ to be used at all appropriate sites except under unusual site-specific circumstances.

This directive establishes containment as the presumptive remedy forCERctA municipal landfills. The framework for the presumptive remedy for these sites is presented in a streamlining manual entitled Conducting RerMdial lnvesriga-rioll.S/F ecis1biliry Snuiiesfor CERCV. Municipal Landfill Sires. February 1991 !OSWER Directive 9355. 3-11). This direcove bighligbts and emphasizes the importance of certain streamlining principles related to the scoping (planning) stages of the remedial investigatioo/feasibiliry study (R{JFS) that were ideotified in dlc manual. The directive also provides clarification of and additional guidance in the following areas: (l) the level of detail appropriate for risk :issessment of source areas a! rnuoicipaJ landfills and (2) the cbaracr.erization of ho! spoa.

BACKGROUND

Superfuodbas conducted pilot projcccsa.t four municipal land.fi.Jl sites' oo the National Priorities List (NPL) to evaluate the effectiveness of the manual Conducting Remedial I nwmigarion.s/F easibiliry Studies/or CERCV. Municipal l.Artdfill Situ (hereafter referred to as "the manual") as a streamlining tool and as the framework for the municipal landfill presumptive remedy. Consistent w i ch the N atiooal Oil and Hazardous Substances PoU ution Contingency Plaa(orNCP}, EPA'sexpectatioa was that contai..o.mcot technologies generally wou Id be appropriate for municipal landfill waste because the volume and heterogeneity of the waste geacrally make treatment impracticable. The results of the pilots support this expectation and demonstrate that the manual is an effective tool for strea.mlining the RJ/FS process for municipal landfills.

·~tWlJapal landfill sit.a rypically coac..lioaoombin.ltiooofpiiocipally m urua paJ and co l lesser e xlC ::it hu:l.rdous w Ula.

Since the manual's development the expectation to contain wast.es at muaicipaJ landfiJls bas e~·olved into a presum9tivc remedy for these sit.es. 1 [mplemeotatioo of the streamlining principles outlined in the m.a.oual at the four pilot sic.cs belped to highlight issues requiring further clarification. such as the degree to wbich risk assessmeocs can be streamlined for source areas and the characterization and remediation of hot spot!. The pilots also demonstrated the value of focusing streamlining efforts a.t the scoping stage. recognizing that the biggest savings in time and money can be re aliz.ed if strcamlinin g is incorporated at the beginning of the R1JFS process. Accordiogly, thls directive addresses those issues identified during the pilots and highlights Streamlining opportuaities to be considered during tbe scopiog component of rbe RI/FS.

'Sec EPA PublicJUoo 9203.1-021. SACM Bulletia.s. P·erumpn•·t Rt-di.u for MwW:rpaJ U:.Nifill Sius. April 1992. Vol. I, No. I, ilDd February 1993, Vol. 2. !'\a.I. and SACM BuUel!ll Prer11.rnpc1>·t Rt-diu. August 1992. Vol.I. No. 3.

I Attachment 4

FII'..lilv. "'hue 1.t1e pnmary focus of lhe :'T1uruc1pal landfill :n:i.r.ul LS 0n streamlirung the RIJFS. Suoeriund's goa1 JnCc~ 5 AC~1 LS t0 acule:r:it.e Lhe en~ ~le:in;.ip process. Ou'ler gwdance issued wider the r;1un1c1pal landfill Fresumpa,·e ~medy iniaanve 1denw:cs design data ll'la1 may be coUected during lhe RlJFS CD scrc:iml.ine lhe 0vc:rJll response process for these si:.:s (see P.Jbl.icauon '."o. 9355.3-18FS. Prtsumpri11t Re~dits: CERCLA UJrw:i:iil C.JlJs Data Col/em.on Cuid.t. tO be published in Oct0.ber 1993).

CONTAINMENT AS A PRESUMPTIVE REMEDY

Section 300.430(a)(iii)(B) of the SCP contains the expectation that engineering ccnuols, such as com.l.lllment. wi1 I be used for waste th.:U poses a relatively low long -term threat or where a-c.lcmem is impracticable. The preamble lO the NCP idenuties municipal landfills as a l)"pe of site where treaunent of the ·.i.astc may be impracucable because of the size ar.d heterogeneity of lhecontentS(55 FR 8704). Waste in CERCLA landfills usually is pre.sent in large vol umcs and is a heterogeneous mixcurc of municipal waste frequently co-disposed with indusaial and/or Mz.ardous waste. Because tre3unent usually is impracticable. EPA generally considers containment to be the appropriate response action. or the "presumptive remedy," for the source aieas of municipal Landfill sites.

The presumptive remedy for CL~CLA municipal landfill siLe.S rela1e.s primarily tO ~nlairunenl of lhe landfill mass and collection and/or treaonent oflandfill gas. In addition. measures tO concrol landfill leachate, affected ground water at the pc rime tcr of the landfill. and/or upgradien l ground-water that is causing saturation of the landfill mas.s may be implemenied as pare of !he presumptive remedy.

The presumptive remedy does noc address exposure palhways outside lhe source area (1andfill), nor docs il include the long-term ground-water response action. Additional Rl/FS activities, including a risk assessmenc. will need to be pcrfonncd. as appropriate, to address those expos~ pathways outside the sowa: area It is expected lhat RIJFS activities addressing exposure pathways outside the source gcnerall y will be condix:ted concurrcmJ y with Che sttcam lined R1/FS for the landfill source presumptive remedy. A response action for exposure pathways outside the soun:e (if any) may be selected iogetherwith the presumptive remedy (thereby developing a comprehensive site response}, or as an operable unit separate from the presumptive remedy.

Highlight l identifies thecompooems of the presumptive remedy. Response actions selected for individual siteS will include only those components th.at a.re n~. based on site-specific conditions.

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Highlight 1: Components of the Presumptive Remedy: Source Containment

Lanatill e

~upporung :n:HenJ..:s 1c ~ . FS re;xins included in Jnalvs1s. te~r.n1~Ji reponsi cJn be provided by HeJdQu.'.U1ers . .lS neeaed.

While lhe uruverse of altem.'.lu-.es lO address the landfill source wiU be !united ID !hose components idenufied in Highlight 1. potenual all.Crn.'.luves I.hat may exist for~ component or combi.nanons of components may be evaluated ll1 lite det.'.U!ed analysis. For eurnple. one component oi the preswnpuve ~mcdy is so~ arc:i ground-waLCl concrol. lf approprial.e. this component may be aa::ompl.i.shed in a nwnbet of ways. including pump and treat. SIWT)' wails. etc. These potential al r.emaoves may then be com bi.ned w i lh other componenis of the presumptive remedy to develop a range of cont.amment altemauves suit.able for site-specific conditions. R~nse altemauves must then be eva1ua1Cd in detail against the nine criteria identified in Section 300.430(eXg) of the NCP. The detailed arulysis will idenufy site-specific ARARs and develop costs on the basis of the parti.Cul.1.r size and volume of the landfill.

EARLY ACTION AT MUNICIPAL LANDFILLS

EPA has identified t.he presumptive remedy site ~gories as good candidates for early action under S ACM. At mwlicipal landfills. the upfront know ledge that the source area will be contained may facilitate such e3rly action.us insrall.ltion of a la.ndf ill cap or a ground-waccrc omairuneru system. Depending on t.hc circumstances, e3rly actions may be accomplished using either removal aulhority (e.g., non-lime

Highlight 2: Generic Conceptual Site Model

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Rate of conwninant release and transport (where possible);

Affected media;

Known and poc.::ncia.J COU!eS of migration: and

• Known and ~cia.J human and environmental rcccptorS.

After rile~ are evaluazod and a site visit is completed. theconcurunarurckasc and aanspatmochani.5ms relevant to the ~tc should be ddennined. The key element in developing the concepcual sit.e model is to identify those aspcctS of the model that require more information to make a decision about response me.3SUJ'CS. Because containmen~ of the landfill's contents is the presumed response acnon. the concepwal site model will be of most use in identifying~ beyond the landfill source itseif lha1 will . ~uire further srud y, thereby focusing site charactenzanon away from the source area and on ~ of poteru:ial conwn inant migration (e.g .. ground water or con t:aminat.ed sediments).

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3. Defining Risks

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The municipal landfill manual staieS that a streamlined or limited baseline risk assessment will be sufficieru to i.rUtiale res]:X)nse action on the most obvious poblcms at a municipal landfill (e.g .• ground wa.Lel', leadwe. landfill coo1.e111S, and landfill gas). One method for establishing risk using a srrC3mlined approach is to compare cootaminant conccna-ation le~ls (tf available) ID Sl3ndards I.hat arc pocemial chemical-specific applicable or n:lcvant and appropriate requirements (A.RAR.s) for the action. The manual states that w~ established standards fer one or more con1311linants in a given medium are clearly exceeded.. remedial action generally is warrarued.'

It is important to ~. however, that based on sitc-spo:ific conditions, an active response is n()( mguj:n;d if ground-water contaminant concentrations cx.ceed chemical-specific~ buL the site risk is within the Agency's acceptable risk range (lo-6 to 104. For example, if it is determined that the release of

'Sec also OSWER Direcli~ 9JSS.0-30. Role of t.M BascliN RirJ: ...UU.U-111 U. S wpc rf.vwJ R UfWJi"J Scueliclt Ot cir iofu, A pril 22. 1991, wtuch •UU3 t1w if ~CU anon-~ MCLGs an:cxca:ded, [a rupons.cl •a.ion gmcnlly is warnnud.

-:ontJJntr .. 1m.s tram a paruc;.D;u l:lnc.f:J t5 decl.Uling, and -:onceiiu:iucns oi one or more groUild-.,.,a:.erconwmnantS :ire J.t or barely excud chem1C.1l-spec.iic sundaliis. the :\ gency may decide not to lITlplernem :in :icuvc ~Such a dee LS ion might be based on the ;mdersunding that the L1J1dfill is no longer acung as a sow-..e oi ground-water cont.lmi.nauon. and chat the landfill does na< present an unaixe;::table nsk from any Olher e:t.i;osure pathway.

A s1t.e gene:-Jily wtll not be eligible for a weamlined risk evaluauon ti ground-water contaml!'larn concentrations do not clearly e:ii:~ chemical-specific standards or the Agency's aLUpted level of risk. or other conditions do not erut that provide a c!e.ar justification for action (e.g .• direct con tact with landfill contents~ ting fron unstable slopes). L'nder these cirt:umstan~. a quantitative risk assessment that addresses all e:itposure pathways will be necessary to determine whetlier acuon is needed.

Cltim.:u.ely. it is neassary LO demonstr.lte !.ha! the final remedy ad~ all pathways J1ld concamlllants of concern. not JUSl those that triggered t.he remedial action. As de.scnbed in the following secuons. lhe ~pwal site model is an effective tool for idennfying those pa.chways and illustrating thaL they have been addressed by the cont.linment remedy.

Streamlined R~k Evaluation Or The Landfill Source

faperience from the presumpuve remedy piloo suppons lhe usefu~ of a sa-eamlined risk evaluation t0 initiate an early~ action Wlder certain cirt:umsunces. As a man.er of policy. for the source arr;i of municipal landfills, a q uan ti ta.ti ve risk ~me nt thac considers ail chemicals. their potenti.aJ additive effects. cu:~ is not necessary co establish a basis for action 1f ground-war.er d.au are available co demonstrate that concam.inan.ts clearly excee.d established standards or if other conditions exist !hat provide a clear jusufication for action.

A quantitative risk assessment also i.s no

LlndfiUs is frequently u~ for residenual purposes. Therefore. baSed on su:e-~lfic cut:umst.ltl~ tt may l:'C appropnare to consider future rc:s1dcnua1 use ior ground warer Jlld cc.her exposure pathways when assessing n.sk from are.as oi comanunant m1grauon.

.4. Developing the Response Action

As a fLtst step in developing containmenl altenutives. response acuon objectives should be developed on the basis of the pathways identified for acuon in the conceptual site model. Typ1cally, the primary response action objectives foe municipal landfill sites include:

Presymotive Remedy

Preventing direct contact with landfill contents;

~finimizing infiltration and resulting contaminant !C3Ching lO ground wat.er.

Controlling surface wat.er runoff and erosion;

Collecting and treating contaminated ground water and leachate to contain the contaminant plwne and prevent furlher migration from source area; and

Controlling and treating landfill gas.

Non-Presump

Highlight 4: Characterization of Hot Spots

II all of the following questions can be ans.vered in the aHirma11ve. rt is likety that charactenzation and: or treatment of hot spots is warrantea:

1. Does evidence exist to indicate the presence and approximate rocat10n of waste?

2. Is the hot spot known to be pnnc1pal tl'1reat waste?"

3. ls the waste in a discrete. accessible part of the landfiU?

4. Is the hot spot known to be large enough that rts remediation will

.., The nc!w resj:'Onse x:.:on consuwteS disposal under KCRA ( 1 e .. :ilsposal baclc uito the onglflal Llndfill). 1

The decision about whether a Subtitle C closure requiremenc is relevan1 llld ar:propqare is based on a vanety of factors, including the nawrc of the waste and itS luza.rdous propenies, the date on which it was disposed. and the naturC of the rcqwremcnt itself. For more infonnauon on RCRA Subtitle C clo~ req~mentS. sec RCRA ARARs: Focus 011 Closure RequirtrrtettLS. Direcuve No. 9234.2-04FS. Cktobcr l989.

~ou: 11'111 dupou..i of on!y smaU qu.anuty hu..ardou1 w•ne and hooaehold haz.udou1 wuu: doc.s noc ma.lr.c Subutlc C applic.ablc.

Notice:

The policies set out in this document are intended solely as guidance to the U.S. Environmental · Protection Agency (EPA) personnel; they are not final EPA actions and do not constitute rulemaking.

These policies are not intended, nor can they be relied upon, to create any rights enforceable by any pany in litigation with the United States. EPA officials may decide to follow the guidance provided in this document. or to act at variance with the guidance, based on an analysis ot specific Sile circumstances. EPA also reserves the right to change the guidance at any time without public norice.

8

APPENDIX A TECHNICAL BASIS FOR PRESUMPTIVE REMEDIES

This Appendix summarizes tre ar.atysis that EPA conducted of feas1bilrty study (FS) and Record ot oec1sf0n (ROD) data from CERCLA municipal lanctill sites which led to the establishment of containment as the presu"'llttve re mecy for these sites. The OOJectlVe of the study was to identify those technologies that are consistently inc!uded in the remedies selected. those that are consistently screened out. and to identify the basis fer their elimination. Results of this analysis suppon the decision to eliminate the initial technology identrtication and screening steps on a site-specific basis for this site type. The technical review found that certain technologies are appropriately screened out based on etfecttveness. i111Jlementab1lity. or excessive costs.

The methodology for this analysis entailed reviewing the technology identification and screening components of the remedy selection process for a representative sample of municipal landfill sites. The numcer of times each technology was either screened out or selected in each remedy was compiled. A detailed discussion of the methodology used is provided below.

METHODOLOGY

ldentifjcatjon of Sites for Eeas1bility Study Analysis

Of the 230 municipal land11ll srtes on the NPL, 149 srtes have had a remedy selected for at least one operable unit. Of the 149 sites. 30 were selected for this study on a random basis, or slightly greater than 20 percent. The sites range in size from 8.5 acres to over 200 acres and are located primarily in Regions 1, 2, 3, and 5. This geographical distribution approximates the distribution of municipal landfills on the NPL.

TectJnoloov Screenjog and Remedial Alternative Analysis

The FS analysis involved a review of the technology identification and screening phase, including any pre-screening steps. followed by a review of the detailed analysis and comparative analysis phases. Information derived I rom each review was documented on site-specific data collection forms. which are available for evaluation as pan of the Administrative Record for this presumptive remedy directive. The review focused on the landfill source contamination only; ground-water technologies and alternatives were not included in the analysis.

For the screening phase. the full range of technologies considered was listed on the data collection forms. along with the key reasons given for eliminating technologies from further consider-ation. These reasons were categorized according to the screening criteria: cost, effectiveness, or implementabifrty. The frequency with which specific reasons were given tor eliminating a technology from further consideration was then tallied and compiled into a screening phase summary table.

For the detailed analysis and comparative analysis, infonnation on the relative performance of each technology/alternative with respect to the seven NCP criteria was documented on the site-specific data collection forms. The advantages and disadvantages associated with each clean-up option were highlighted. In some cases. a technologywascombinedwrthoneormore technologies into one or more alternatives. The disadvantages ol a technology/alternative were then compiled into a detailed analysis/comparative analysis summary table, under the assumption that these disadvantages contributed to non-selection. All summary tables are available for review as part of the Administrative Record.

9

APPENDIX A TECHNICAL BASIS FOR PRESUMPTIVE REMEDIES (continued)

RESULTS

The information from the technology screening and remedial alternative anatyses is provided in Table 1. It demcnstrates that containment (the presumptive remedy). was chosen as a component of the selected remedy at all thirty of the sites analyzed. No other technolog1es or treatments were consistentty selected as a remedy or retained tor consideration in a remedial alternative. However. at eight of the thirty sites. there were circumstances where techno6ogies were included in the selected remedy to address a site-specific concern. such as principal threat wastes. These technologies are induded in the column entitled "Tech. Not Primary Component of Alternative"' in Table 1 and include inoneration at two sites. waste removal and off-site disposal at two sites, soil vapor extraction at two srtes. and bioreclamation at one site.

Leachate collection and gas collection systems were also tracked as part of the detailed analysis and companson of remedial alternatives. These types of systems generally were not considered as remediation technologies during the screening phases. At fifteen sites. leacnate collection was selected as part of the overall containment remedy. At seventeen sites. gas collection systems were selected as part of the overall containment remedy.

This analysis supports the decision to eliminate the initial technology identification and screening step for municipal landfill sites. On a site-specific basis. consideration of remediation technologies may be retained as needed.

' This column title is used for record-keeping purposes only and is not meant to imply that these treatment lechnolog1es are no1 considered important components of the selected remedies.

10

-.....

(

TABLE 1 •SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR LANDfll.LS 1

~_,dY~r.::·.::.:.....~~/ IROOsW11mCR1uaoCotnHWUllOIONOHSttLCIH• ~ cf> ~ ~ ~,, 3 ~- ~- --TECHNOLOGY

2 ~ cp y.~(I. ~ ToScr.nlrtOul ~ '\ ~ (Sfr~.7 ~ 4 ,\\ 4

/*W~~·~/~/::?5?.-' ~- ~·A~ ...r~ if .~~ ,~,. _,,,;;,• ~ \

...... N

(

TABLE 1 • SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR LANDFll.l.S (Continued) 1

/~a% i"r·:.!·c:i:.. ... k / . ROOs WHERE CA•IA•a. CoNlR18UlEO 10 NoH-SUECllU. ~cf'~-~ 3~~-.

TfCHHOLOOY 2 . ~ cp ~ ~ Tosa-lngOul "\ "\ J. 4 ~

/~~p:~• ,;/~~/~~ #' ~~ 4 #..:;. .; / ;/" ur:/ '/ .. ~ ,ff. c; / \.. / - '(' ,~ ~ Vibrating

5 0 5 0 0 3 3 0 0 0 0 0 0 0 0 0 -- .. Beam

lln«I 2 0 2 0 0 1 2 0 0 0 0 0 0 0 0 0 -· -

on1o1 .. Nonhu11dou1 3 0 3 0 0 0 3 0 0 0 0 0 0 0 0 0 .. l.andliU

OllslttRCRA 17 0 13 4 8 3 12 0 0 0 0 0 0 0 0 0 l.andfiU

OHsltt Landfill 9 1 8 0 s 3 5 1 0 0 0 0 0 0 0 0 .. .. (unspecified)

Onsito Nonhazardous 2 0 2 0 I I 1 0 0 0 0 0 0 0 0 0 landl1I

OnsJ11 ACRA 14 1 '11 2 3 2 10 landhM

0 I 0 0 0 0 0 0 I

Onsilt Landhl 7 0 6 I 3 3 6 0 0 0 0 0 0 0 0 0 (unspegfied)

Bloremecbllon 13 0 13 0 0 13 1 0 0 0 0 0 0 0 0 0 .. ( unspec:lfied)

Bioremedlalion 10 0 10 0 0 7 7 0 0 0 0 0 0 0 0 0 .. ..

El·situ

Bioremecilllon 15 I 14 0 I 13 7 I ltulll

0 0 0 0 0 0 0 0 -- --

OechlorinludM' 0 0 0 0 0 0 0 ..

APEG 6 5 1 I 4 2 0 0 0

Olidatlc>N 0 0 0 0 0 0 .. ..

RlductlDn 12 0 12 0 I • 5 0 0 0

(

TABLE 1 •SUMMARY OF SCREENING AND DETAILED ANALYSIS fOR LANDflU.S (Continued) I

'

TECHNOLOGY 2 ~

...... ~

( (

TABLE 1 • SUMMARY OF SCREENING AND DETAILED ANALYSIS FOR LANDFILi.$ (Continued) 1

/._.Jo cf>~ ~.:.!1c':n'i:-Med~ A/ I ROOs WHERE CR1u1a. CoHTR18llTEO 10 NoH-Sfl EC114 T OY 2 ~ ~ ~~~ ~~ ToS-klgOul3 '\",Jr' '\',p'J> 4 , ECHNOlO cp ~ ~ ,,t-\

/~~~· V~/9~ ~ ':1/ h- ~;, c-P / ~·· "'"" ""/ .f( ,ff c; / n cttwla ar• no1 equa1 D h runbtr ol FS1 and ROO. conlldlred. 4 ln.,,,.,_llon on Staie and corrrnunlly concerna ••not Wludld In til analylll bec:auM FS1 do not conleln '111 inlormaion and R001 genwelly Drtt rel~ aupponng doNnlnll•on (Le., Sta• concurrence Ill• and re1ponaivent1111MM1MY).

barcode: *2395*barcodetext: SDMS Doc ID 2395