PROPOSED N O A C T I O N P L A N F O RS T O C K P I L E D F I N E S L A G

U.S. Environmental Protection AgencyRegion V I I I , ; - ' "September 1996

Arkansas V a l l e y S m e l t e r S l a g PileC a l i f o r n i a Gulch S u p e r f u n d S i t e

L e a d v i l l e , Colorado389141EPA Announces Its Preferred Alternative

The U . S . Environmental Protection Agency (EPA) requestspub l i c comment on its preferred alternative for s t o c k p i l e df i n e s lag at die Arkansas V a l l e y smelter s lag p i l e ofOperable Uni t 3 ( O U 3 ) within the C a l i f o r n i a G u l c hS u p e r f u n d S i t e in L e a d v i l l e , Colorado. EPA is the leadagency and is assisted by the Colorado Department ofPublic H e a l t h and Environment ( C D P H E ) , which is the sup-port agency at this site.The preferred alternative for stockpiled f ine slag at theArkansas Val l ey slag p i l e is "No Action," with a contin-gency for fu ture util ization of the slag, as described moref u l l y later in this plan. EPA recommends this alternativebased on the resul t s of the risk assessment and a f t e r a care-ful evaluation of site data. The C D P H E has reviewed thisp l a n and concurs with the proposed approach. T h i s

Proposed Plan f u l f i l l s the requirements o f theComprehensive Environmental Response Compensat ion,and L i a b i l i t y Act ( C E R C L A ) S e c t i o n 117 (a) (notice ofava i lab i l i ty).T h i s Proposed Plan summarizes in format ion that can bef ound in greater detai l in the Final Stockpiled Fine SlagFeasibility Study Report (FS), which is available for yourreview at the in format ion reposi tories l i s t e d below. TheProposed Plan is based on the conclusions of the FS anda p p l i e s only to the s t o c k p i l e d f in e s lag at the ArkansasV a l l e y p i l e . During the remedial inve s t igat ion, site datawere used to assess the v i a b i l i t y of f i v e p o t e n t i a l contami-nant release mechanisms (or transport p a t h w a y s ) i d e n t i f i e din the conceptual site model (CSM) for the slag pi le s: wind,leaching, mixing by human a c t i v i t i e s , r u n o f f of p a r t i c u l a t e s ,

M A R K Y O U R C A L E N D A R : O P P O R T U N I T I E S F O R P U B L I C I N V O L V E M E N TPublic Meeting:Thursday, Octobers, 1996, 7:00p.m.N a t i o n a l Mining H a l l of Fame and Museum(10th Stree t Entrance)L e a d v i l l e , Colorado

Public Comment Period:S e p t e m b e r 27 - October 28, 1996Send Comments to:Rebecca Thomas ( 8 E P R - S R )EPA Remedial Projec t Manager999 18th Stre e t , S u i t e 500Denver, Co lorado 80202-2405

Key Contacts:Rebecca ThomasEPA Remedial Pro j e c t Manager( 3 0 3 ) 3 1 2 - 6 5 5 2T o l l - f r e e (800) 227-8917 x 6552Rus s e l l A l i e nC D P H E S t a t e Pro j e c t O f f i c e r(303) 692-3382

Informat ion Repositories:The Proposed Plan and other documents

in the Administrative Record are availableat the following locations:

Lake County Public Library1 1 1 5 Harrison Avenue

L e a d v i l l e , Co lorado 80461Colorado Mountain College Library

Learning Resource CenterL e a d v i l l e , CO 80461

EPA Superfund Records Center999 18th S t r e e t

5 th F l o o r , N o r t h TerraceDenver, CO 80202

(303) 312-6473

and direct contact. Of these, only one potent ial releasemechanism, leaching, was retained for the s lag p i l e s .There f or e , a remedial action object ive was established toprevent leaching of metals of concern in concentrations thatwould have an adverse impact on soils , surface water, orgroundwater in the area near the s lag p i l e s .The FS report provides a de ta i l ed analysi s of the three alter-natives considered for s t o ckp i l ed f in e s lag at the ArkansasVal l ey pile. These alternatives, which were retained f o l l o w -ing screening in 1993, are no action, ins t i tut ional controls,and resource u t i l i za t i on . EPA encourages communityinvolvement in the remedy selection process and invitespub l i c comment on all alternatives.

P U B L I C I N V O L V E M E N T P R O C E S SEPA encourages residents and other interested parties toread and comment on this Proposed Plan, the FinalReport for Lead Slag Pile Remedial Investigation at theCalifornia Gulch Site, Leadville, Colorado (RI), and theFS. The s e documents describe the results of site investi-gations and the cleanup alternatives considered. TheProposed Plan is based on f i n d i n g s of the RI, the FS, andother pertinent documents. The s e reports are located inthe information repositories and are included in theA d m i n i s t r a t i v e Record f or th e C a l i f o r n i a G u l c hS u p e r f u n d S i t e . The Admini s tra t ive Record contains allof the information upon which the selection of the reme-dy wi l l be based.EPA will make its f inal remedy selection only a f t er con-sidering all state and community comments. EPA maym o d i f y the pre f erred alternative, select another alterna-tive presented in this p lan, or select a more appropria t ealternative based on new information or pub l i c com-ments. EPA encourages the p u b l i c to review and com-ment on all i d e n t i f i e d al ternatives , as well as to provideany new information for EPA's consideration. Later thisyear, EPA will publ i sh a Record of Decision (ROD) thatre sponds to community comments and documents

EPA Announces PreferredA l t e r n a t i v e .................. .p. 1Public Involvement Process . . . . . . . . p . 2S i t e Background ............... .p. 2

A s s e s s m e n t of S i t e Risks ........ .p. 5Summary of A l t e r n a t i v e s . . . . . . . . . . p . 7C l e a n u p Evaluation Criteria . . . . . . .p . 8Compari son and Evaluat ion

of A l t e r n a t i v e s . . . . . . . . . . . . . . . .p. 9Description of Preferred

A l t e r n a t i v e .................. .p. 9A c r o n y m s / G l o s s a r y ............. .p. 10

the rationale for its decision. The ROD will containresponses to comments on the Proposed Plan.T h i s Proposed Plan i s prepared to ful f i l l EPA's publ i c par-t i c ipat ion r e spons i b i l i t i e s under S e c t i o n s 1 1 3 ( k ) and1 1 7 ( a ) of the Comprehensive Environmental Response,Compensation, and L i a b i l i t y Act ( C E R C L A ) of 1980, asamended by the S u p e r f u n d Amendment s andReauthorization Act (SARA) of 1986.Comments on the Proposed Plan and FS may be submit-ted either orally or in writing at the October 3,1996 pub-lic meeting, or you may send written comments, post-marked no later than October 28, 1996, to RebeccaThomas at the address provided on page 1. Upon t i m e l yrequest, the comment period may be extended. Suchrequests should be submitted in writing to RebeccaThomas at the EPA address provided on page 1 and mustbe postmarked no later than October 28, 1996.

S I T E B A C K G R O U N DS i t e History. The C a l i f o r n i a G u l c h S u p e r f u n d S i t e (here-after, the s i t e) is located in and around the community ofL e a d v i l l e , Colorado, about 100 miles southwest ofDenver ( F i g u r e 1). B e g i n n i n g in about 1860, theL e a d v i l l e area was used e x t en s iv e ly for mining, m i l l i n g ,and smelting operations. Si lver , g o l d , copper, l ead, andzinc were mined by underground and p lacer methodsfrom within the site. A p p r o x i m a t e l y 17 smelter f a c i l i t i e sare reported to have once operated on site. Most opera-tions ceased by about 1900, a l t h o u g h some f a c i l i t i e s con-tinued to operate into the 1920's, such as Western Z i n c ,and the into the 1960's, such as the Arkansas V a l l e ySmel t er . At present, nearly all of the mines within the s i t eboundaries are inactive; only a few small to moderate-sized mining operations exist. All of the m i l l s andsmelters once s i tuated on site have been d e m o l i s h e d .Due to historic mining, m i l l i n g , and sme l t ing opera t i on s ,the site contains many t a i l i n g s impoundment s , f l u v i a ld e p o s i t s , s lag p i l e s , waste rock p i l e s , and mine waterdrainage tunnels. S l a g on site is the mineralized wastebyproduc t of s m e l t i n g and r e su l t s f rom the processing oflead ore in high temperature furnace s . Three major s l a gp i l e s and several sma l l e r p i l e s remain at the s i t e ( F i g u r e2). In 1961, the Denver and Rio Grande WesternRailroad ( D & R G W ) purchased th e Arkansas V a l l e y s l a gp i l e f r om A S A R C O for use as railroad ba l la s t . D & R G Wpurchased the La Plata s l a g p i l e f rom the L e a d v i l l eS a n i t a t i o n Distric t in 1970. A d d i t i o n a l l y , D & R G W pur-chased t h e Harrison Stree t S l a g P i l e f rom N L I n d u s t r i e s

L e a d v i l l e

CaliforniaGulch NPLSite

Lake C o u n t yL e a d v l l l e / » r

! C O N T I N E N T A L D I V I D E

F I G U R E 1General S i t e Locat ionj : \ ca lgul ch\12d24800\wp\ lakemap3.ep s

U)

- - fasr 1 - — — - k - I IlOPOCWPHC CONTOUDS "» SURFACE FEA1URCSPROVDED BT INTRASCARCH

J

F I G U R E 2S L A G P I L E L O C A T I O N M A PSourc e : T E R R A N E X T 1996

in 1983. T h i s Proposed Plan addresses only f i n e s lagstockpiled as a subpile of the Arkansas Val l ey slag pile.Regulatory History. In 1983, ERA. placed the Cal i f orn iaGulch site on the National Priorities List (NPL), becauseof concerns about the impact of mine drainage on surfacewaters in the Cal i f orn ia Gulch and the impact of heavymetals loading to the Arkansas River. Subsequent investi-gations revealed the presence of heavy metals in soils andwaste p i l e s in and around residential and commercialareas of Leadvi l l e . A preliminary risk assessment indi-cated that contaminant levels , par t i cu lar ly levels ofarsenic and lead, were high enough to be of potent ialhuman health concern.On December 3 , 1 9 9 1 , EPA and D&RGW entered into anAdminis trat ive Order on Consent (AOC) for the per for-mance of a remedial i n v e s t i g a t i o n / f e a s i b i l i t y s t u d y(RI/FS) of the lead s lag p i l e s . Prior to the AOC, EPA hadstudied the slag pi l e s as part of other investigations at thesite. In 1992, D&RGW performed an RI that addressedseven lead s lag p i l e s , inc luding the Arkansas V a l l e y ,Harri son, and La Plata slag p i l e s , and one zinc slag p i l e .F o l l o w i n g the RI, a S i t e - W i d e Screening F e a s i b i l i t yS t u d y (SFS) was undertaken as a j o in t e f f o r t between thep o t e n t i a l l y re spons ib l e parties and EPA. The SFS wasc o m p l e t e d in March 1993. It screened several remedia-tion alternatives for all types of slag located on the sitebased on s p e c i f i c criteria, such as relative cost, imple-m e n t a b i l i t y , and e f f e c t i v e n e s s . The three retained alter-natives for fur ther evaluation were: no action, institu-t ional controls, and resource u t i l i z a t i o n (material s reuse).On December 15, 1993, D&RGW entered into a ConsentDecree with EPA to p er f orm the remainder of their sitework. The consent decree stated EPA's concerns regard-ing the f i n e f rac t i on of the s t o ckp i l ed s lag and the poten-t ia l for paniculate release during ba l la s t operations as apot ent ia l human health exposure pathway. The consentdecree required D&RGW to per form a f e a s i b i l i t y s tudyfor s t o c k p i l e d f i n e s l ag and to submit an operations p lanbe fore in i t ia t ing any ba l la s t operations. In July of 1995,D&RGW submitted a b a l l a s t operations p lan to EPA.F o l l o w i n g EPA's approval o f th e plan, bal las t operationscommenced in A u g u s t 1995. B a l l a s t operat ions involvethe sort ing of larger s l a g so that the size f r a c t i o n ofgreater than 3/8 inch and l e s s than 2 1/2 inches is pro-duced for railroad b a l l a s t . The undersized f ra c t i on (i.e.,less than 3/8 inch), or sorted f i n e s l ag , that is produced bythe sorting process is s t o c k p i l e d along with the previous-ly sorted f i n e s l ag at the Arkansas V a l l e y p i l e .

During the early part of 1995, a baseline human healthrisk assessment was undertaken that fur th er assessedpot ent ia l human health risks from exposure to heavy met-als at the site. A result of the f inal baseline risk assess-ment was a Proposed No Action Plan for commercial andrecreational land uses at the site. The Proposed Planaddresses areas within the site currently zoned commer-c i a l / i n d u s t r i a l and areas used for non-residential recre-ational purpose s . Five commercial/industrial areas at thes i te, inc luding the Arkansas V a l l e y s lag p i l e , were s p e c i f -i ca l ly excluded from the 1995 Proposed No Action Planbecause of concerns related to high level s of lead. Twoother proper t i e s within OU3, the former D&RGW rail-yard and the easement through town, were included in theareas which carry the no action designation. The con-centrations of lead in soi l s within the railyard were belowthe level of concern, al though D&RGW has i d e n t i f i e d asmall area with f ine s lag in the railyard. D&RGW hasprepared a plan which addresses removal and control off in e s lag from this area. The f ine slag is to be removedfrom the railyard and consol idated with the s t o c k p i l e df in e s lag at the Arkansas V a l l e y pi l e . The easementthrough town was evaluated and determined not to con-tain concentrations of lead which would be of concern ina recreational se t t ing. As long as land use remains recre-ational or commerc ia l / indus tr ia l , no action will be neces-sary.In May of 1996, D&RGW submitted a f e a s i b i l i t y s tudyf or the s t o c k p i l e d f i n e s l ag (the FS) at the Arkansas V a l l e yp i l e , according to the terms of the Consent Decree. Theex i s t ing f i n e s l ag s u b p i l e and f i n e s l ag p o t e n t i a l l y gener-ated from f u t u r e b a l l a s t product ion were the f o c u s of theFS. The FS provided a detailed analysis of the threeretained remediation al ternat ive s from the SFS as a p p l i e dto the s t o c k p i l e d f i n e s lag.

A S S E S S M E N T O F S I T E R I S K SThe prel iminary risk assessment i d e n t i f i e d lead andarsenic as the primary chemicals of po t ent ia l concern atthe site. Since the comple t ion of the preliminary riskassessment, several important s t ud i e s were c o m p l e t e dthat provided more extensive and more r e l i a b l e data onenvironmental concentrations and on human exposures .T h e r e f o r e , a base l ine human h e a l t h risk assessment wascompl e t ed to incorporate all r e l i a b l e data into a f i n a l riskassessment for the site: Part A evaluates risks to r e s ident sf r om l e a d ; Part B evaluates risks to re s ident s f rom met-als other than lead; and Part C evaluates risks to workersin the commercial and business d i s t r i c t and to recreation-al users in areas in and around the community. The f o l -

5

lowing paragraphs summarize results of the f inal baselinerisk assessment as they relate to the s to ckpi l ed f ine s lagat the Arkansas V a l l e y p i l e .

R E S I D E N T I A L R I S K A S S E S S M E N TExposure pathways determined to be the most importantfor contact with mine-related waste at the site includedinadvertent ingestion of contaminated soil and dust, inad-vertent ingestion of material at waste p i l e s (such as, wasterock, ta i l ings , or s lag), and ingestion of impacted ground-water. Other pathways of exposure to mine-related waste(i.e., inhalation of airborne part iculate s , dermal contactwith contaminants in soil or dust, ingestion of home-grown vegetables, and ingestion of f i s h from contaminat-ed surface waters) were j u d g e d to be s u f f i c i e n t l y minorthat quantitative evaluation was not warranted.Residential Exposure to Slag . The evaluation of expo-sure to contaminants at waste p i l e s included considera-tion of slag p i l e data, with an exposure scenario conserv-atively evaluating a child p l a y i n g on the waste p i l e s whomay come into contact with contaminants through inad-vertent ingestion or dermal (skin) contact. The dermalcontact pathway was determined to be minimal and wasnot considered further. The res idential risk assessmentalso determined that non-lead metals in most waste p i l e spose either no risk or only low risk from direct contactwhile p l a y i n g on the p i l e s . For the evaluation of leadexposure at the waste p i l e s , the data were found to be tool imi t ed to derive rel iable es t imates of the potent ial impactof direct exposures to children who play on waste pi le s;however, model estimates sugge s t ed the e f f e c t could besubs tantial , d ep end ing on the concentration of lead in thewaste p i l e and the frequency and extent of contact. It wasf u r th e r concluded that waste p i l e s can contribute to expo-sure not only through direct exposure to children whop lay on the p i l e s , but also indire c t ly by serving as asource of lead contamination in nearby yards and homes(contaminant migration to nearby yards and homes bytransport of airborne part i cu la t e s).Wind erosion and direct contact were not consideredviable release mechanisms for the s t o ckp i l ed f i n e s lag inthe SFS. However, based on the re su l t s of the risk assess-ment, EPA maintains some concern about the potent ia lfor p a n i c u l a t e release and human exposure shouldresource ut i l izat ion of the s tockpi l ed f i n e slag be under-taken. (For example , inhalation of s lag par t i c l e s couldoccur if the material is dis turbed from its current state).If the resource u t i l i z a t i o n op t i on is exercised, measureswould be required to prevent contaminant releases.6

Residential Exposure to I m p a c t e d Groundwater. Theremedial action objec t ive in the 1993 SFS was to preventleaching of metals of concern in concentrations thatwould have an adverse impact on soi l s , surface water, orground water in the area near the slag pi le s . When thegroundwater exposure pathway was evaluated in the 1996f inal baseline risk assessment, data indicated that inges-tion of the water from the shal low aqui f er beneath someof the large tai l ings p i l e s along C a l i f o r n i a Gulch wouldbe of very high concern to children. However, the 1996FS determined that t e s t ing in material under the s lag p i l edid not indicate that migration of contaminants by leach-ing from the s lag contributes to elevated metals beneaththe slag piles. In addi t ion, the f inal baseline risk assess-ment determined that groundwater from this aqui f er isnot currently used for drinking, and it is relat ively unlike-ly that it wil l be used for drinking in the fu ture . EPA hasdetermined that there is minimal po t en t ia l for release ofmetals in leachate from the s tockpiled f ine s lag, and thatthe s t o ckp i l ed f ine s lag poses, at most, an in s igni f i cantimpact on water quality.

N O N - R E S I D E N T I A L R I S K A S S E S S M E N TLeadv i l l e o f f i c i a l s and business leaders expressed con-cern about p o s s i b l e risks and l i a b i l i t i e s associated withcommercial and recreational uses wi th in the si te.There for e , in the f inal baseline risk assessment, EPAevaluated the risks posed by environmental contamina-tion to current or fu tur e workers in the commercial andbusiness di s tr i c t of the community and to p e o p l e whoengage in recreational ac t iv i t i e s in areas in and aroundthe community. The assessment was conducted to deter-mine if environmental contamination was of concern atany site locat ions pr e s en t ly zoned commerc ia l / indu s t r ia land to address concerns regarding the development of aproposed bike path around the community.Recreational User Exposure to S l a g . The EPA pro-posed no action for non-residential recreational uses atthe site in the 1995 Proposed No Action Plan, based on acomparison of action l eve l s derived in the risk assessmentfor recreational land use and measured and pred i c t ed sur-f i c i a l soil concentrations for both lead and arsenic. Theno action response a p p l i e d to all areas of the site that areused for recreational ac t iv i t i e s such as hiking, b ik ing,hunting, and rock hounding, and inc luded that area of thesite proposed for construction of the Mineral Belt BikePath. The s l a g p i l e area is s i tuated in an area p r e s e n t l yzoned as i n d u s t r i a l / m i n i n g and is not considered a recre-ational use area.

Worker Exposure to Slag. The area of the ArkansasV a l l e y , Harrison, and La Plata s lag p i l e s were exceptedfrom the 1995 Proposed No Action Plan because of con-cerns about extensive level s of lead and po t ent ia l expo-sure to workers in the commercial/industrial area of thecommunity. The worker risk assessment used the f o l -lowing approach:• Lead and arsenic were evaluated as the chemicals

of concern. Even though other metals occur atincreased concentrations in the environmentaround L e a d v i l l e , experience at other sites, aswell as results of preliminary calculations, indi-cated that lead and arsenic are the "risk drivers."

• The ingestion pathway was evaluated as themajor pathway of concern. Exposure to soil anddust was evaluated for workers. Exposure toother media such as waste p i l e s , surface water,and sediments and exposure to s o i l /du s t via otherpathways such as skin contact and inhalation ofairborne particulates were considered to be ofminor concern for workers.

• Because of uncertainties regarding actual level sof exposure of workers, EPA did not calculate asingle concentration (action l eve l) that wouldi d e n t i f y an area as being of concern, but rathercalculated a range of soil concentrations thatcould be considered protective for the commer-c i a l / i n d u s t r i a l land use. W h i l e all of the valueswithin the range are credible, values from thecentral portion were considered to be more l i k e l yappropriate than values at the low end or the highend.

• The po t en t ia l for heal th risks for lead and arsenicwas evaluated by comparing risk level s f rom thecentral portion of the range with maps showingthe measured or est imated concentrations of leadand arsenic across the site. Areas where the con-centrations were below the central range of riskl eve l s were j u d g e d to pose no unacceptable heal thrisks, while areas with po t en t ia l for extensivecontamination above the central range of actionl eve l s were considered to be of concern, requiringfur th er remedial response. It is also important tonote that it is the average concentration overd e f i n e d exposure areas that was compared to thedecision criterion, rather than values measured ats p e c i f i c s a m p l i n g locat ions .

For evaluation of lead exposure, the risk assessmentfocu s ed on f e m a l e workers who were pregnant or mightbecome pregnant, based on health-based data that thef e t u s of a pregnant worker is e s p e c i a l l y s u s c e p t i b l e to thee f f e c t s of lead. In order to determine lead action l eve l s ,the risk assessment calculated levels of lead in soil thatwould ensure that the mother would have a low chance ofhaving a blood lead level that might expose the f e t u s tounacceptable level s of lead. The risk assessment estimat-ed that lead action levels for pregnant workers couldrange f rom 2,200 parts per mi l l i on ( p p m ) to 19,100 ppm,with central tendency values in the 6,100 to 7,700 ppmrange. After comparing the central tendency l eve l s tomeasured or estimated concentrations of lead in so i l s ,EPA proposed no action for commercial uses of the site,with the excep t ion of f iv e site areas i n c l u d i n g theArkansas V a l l e y slag pile s .A lead action level in a commercial/ indus tr ial a p p l i c a t i o nwas proposed at 7,000 ppm in the FS for remediation ofsoil s in and around the s lag p i l e s . Based on the results ofsubslag sampling conducted during the RI, the maximumconcentrations of lead in all subs lag sample s was 794milligrams per kilogram (mg/kg is equal to p p m ) , wellbelow the lead action level.Action l eve l s were determined in the risk assessment forarsenic in soil and ranged from as low as 330 ppm to ashigh as 1,300 ppm, with central tendency values in the610 to 690 ppm range. The EPA determined that thereare no i d e n t i f i e d areas within the site which containarsenic at l ev e l s of concern under a commerc ia l / indus t r i -al scenario.

S U M M A R Y O F A L T E R N A T I V E SA wide range of c l eanup op t i on s were considered in theSFS. Some were el iminated during preliminary screen-ing because they would not e f f e c t i v e l y addre s s contami-nation, could not be implemented, or would have hadexcessive costs compared to other protec t ive al ternatives .F o l l o w i n g screening, three al t ernat ive s were retained forf ur th er evaluation for the f i n e s lag s u b - p i l e of theArkansas V a l l e y smel ter s lag p i l e . T h e s e a l t e rna t iv e swere: (1) no action, (2) i n s t i t u t i o n a l control s and f e n c -ing of the s t o c k p i l e d f i n e s l a g , (3) resource u t i l i z a t i o n .T h e s e a l t ernat ive s were compared and evaluated usingEPA's nine eva lua t i on cr i t e r ia de s cr ibed in t h e nextsection.

C L E A N U P E V A L U A T I O N C R I T E R I A

The three alternatives retained for s tockpiled f ine slag were evaluated in the FS using the nine criteria summa-rized below. In asses s ing alternatives, all must meet Criter ia No. 1 and No. 2.

1. Overall Protection of HumanH e a l t h and the Environmentaddresses whether a remedy is pro-tective and describes how risksposed through each pathway are el iminated,reduced, or controlled.

5. Reduction of Toxic i ty , Mobi l i ty ,or Volume through Treatmentrefers to the preference for a reme-dy that reduces health hazards, themovement of contaminants, or thequantity of contaminants at the site throughtreatment.

2.

3.

Compliance with A p p l i c a b l e orRelevant and Appropr ia t eRequirements (ARARs) addresseswhether a remedy will meet alla p p l i c a b l e f edera l and state envi-ronmental laws and other relevant and appro-priate requirements and/or provide groundsfor a waiver.

S h o r t - T e r m E f f e c t i v e n e s s address-es the period of time needed tocomple te the remedy, and anyadverse e f f e c t s to human health andthe environment that may be causedduring the construction and implementationof the remedy.

I m p l e m e n t a b i l i t y refers to thetechnical and administrative f ea s i-b i l i t y of an alternative or a remedy.It includes the ava i lab i l i ty of mate-rials and services needed to carryout a remedy. It also inc lude s coordination off e d e r a l , state, and local governments to worktogether to clean up the site.

Cost E f f e c t i v e n e s s evaluate s theestimated c a p i t a l , operat ion, andmaintenance costs of each al ter-native in comparison to other p r o t e c t i v eal t ernat ive s .

State Acceptance indicateswhether the state agrees with,oppo s e s , or has no comment on thepreferred alternative.

4. Long-Term E f f e c t i v e n e s s andPermanence refers to the ab i l i ty ofa remedy to provide r e l iab l e protec-tion of human health and the envi-ronment over time.

9. Community Accep tance includesdetermining which components ofthe al t ernat ive s interested personsin the community s u p p o r t , havereservations about, or oppose.T h i s assessment may not be comple t ed untilpubl i c comments on the proposed plan arereviewed.

C O M P A R I S O N A N D E V A L U A T I O NO F A L T E R N A T I V E S

The FS was deve loped to address the alternatives evalua-tion for the s tockpiled f ine slag at the Arkansas Val l ey s lagp i l e at the site. The FS performed a de ta i l ed analysis ofthe three alternatives retained from the SFS using EPA'snine evaluation criteria. A summary of the analysis ofeach retained alternative is provided below.A l t e r n a t i v e 1; No Action. General ly, the No Act i onAlternat iv e is provided for consideration as a baselineagainst which other technologies can be compared, inaccordance with the National Contingency Plan (NCP).For the s t o c k p i l e d f in e s lag , the No Act i on Alternat ive i sproposed to leave the material in p lace with no remedia-t ion, engineering controls , ins t i tut ional controls, or long-term maintenance. No action is protect ive of humanhealth and the environment and is considered e f f e c t i v ebecause no comple t e human exposure pathways wereiden t i f i ed for the s tockpiled f ine slag and because thepo t en t ia l for release of metals in leachate from the stock-p i l e d f i n e s lag is minimal. T h i s alternative is t e chnical lyf e a s i b l e and cost e f f e c t i v e , since it does not rely on anytechnology and has no cost.A l t e r n a t i v e 2: I n s t i t u t i o n a l C o n t r o l s / F e n c i n g of theS t o c k p i l e d F i n e Slag. Insti tutional controls involveres tr i c t ing access or act ivi t ie s that could increase thepotential for leaching from s to ckpi l ed f ine s lag, for exam-p l e , f e n c i n g , land-use restrictions, or deed restrictions.Deed restrictions are already recorded for the s t o c k p i l e df i n e s lag. The opt ion considered is to f ence and maintainthe s t o c k p i l e d f i n e s lag located at the Arkansas V a l l e y s lagpi l e . Fencing would eliminate the potential direct contactpathway with the f i n e s lag p i l e s . F e n c i n g would be pro-tective of human health and the environment because nocomple t e human exposure pa thways would exist (that is,ch i ldren would not have access to the p i l e s ) , and becausethe po t ent ia l for release of metals in leachate f r om thes t o c k p i l e d f i n e s lag would remain minimal. F e n c i n gwould be technically f ea s ib l e . Costs associated with fenc-ing are $161,000 with inspec t ion and maintenance costs of$8,500 for a 30-year period.A l t e r n a t i v e 3; Resource Uti l i za t i on . Two op t i on s forresource u t i l i z a t i o n (mat er ia l s reuse) were i d e n t i f i e d in theFS: 1) to process s l a g for use as a concrete or a s p h a l taggregate in construction, and 2) to use s lag materials fora s tand-alone material in construct ion, such as b a c k f i l l orp i p e bedding. Resource u t i l i za t i on would be protect ive ofhuman hea l th and the environment because a p p r o p r i a t eenvironmental control s for p a r t i c u l a t e s emissions and

stormwater would be required to control contaminantreleases. Resource utilization may marginally decreasethe minimal metals concentrations in the s t o c k p i l e d f i n es lag leachate through overall volume reduction. However,the e f f e c t i v e n e s s and i m p l e m e n t a b i l i t y of this alternativewould be a f f e c t e d by the regional market demand for thematerial. E f f o r t s conducted to i d e n t i f y markets have beenunsucce s s fu l to date, but a po t en t ia l for fu tur e marketsexists and, therefore, this alternative is proposed as a con-tingency with "No Action" as the preferred alternative.Cost e f f e c t i v e n e s s is hindered by the distance the s lagmaterial is located from a major market and the cost asso-ciated with sorting the slag. Cost for use of the f i n e s lagas aggregate is estimated as a $1,120,000 loss a f t er resale,while the cost for use as fill material is estimated as a$244,625 loss a f t e r resale.

D E S C R I P T I O N O F N O - A C T I O NPREFERRED A L T E R N A T I V E

The FS used a comparative analysis of alternatives to qual-i ta t ive ly evaluate each alternative and i d e n t i f y the advan-tages and di sadvantage s of each alternative r e la t ive to theothers, as well as to i d e n t i f y key t r a d e o f f s . A grid com-parison method was used to rank the a l t ernat ive s and theirattainment relative to the NCP criteria set f o r t h in the SFS.A l t e r n a t i v e s were ranked on a scale of 1 to 5, with 5 be ingthe highest attainment of the criterion. Total scores foreach alternative were: Alternat ive 1: No A c t i o n at 41;A l t e r n a t i v e 2: I n s t i t u t i o n a l Contro l s at 39; and A l t e r n a t i v e3: Resource U t i l i z a t i o n at 36. S e l e c t i o n of the No A c t i o nA l t e r n a t i v e was based on these result s .The No Action A l t e r n a t i v e leaves sources in their e x i s t i n gcondition with no control or c l e a n u p p l a n n e d and is s e l e c t -ed for resources that pose no risk to human heal th or theenvironment. The No Act i on A l t e r n a t i v e i s p r e f e r r e d withthe contingency that resource u t i l i za t i on may be undertak-en in the fu ture . Resource u t i l i z a t i o n involves use or reuseof the source material as a commercial product whichremoves the source p a r t i a l l y or t o t a l l y from the site.Based on subslag sampling, metals have not leached andwil l not leach f rom the s t o c k p i l e d f i n e s l a g in concentra-tions that wil l have an adverse impact on s o i l s , sur facewater, or groundwater in the area. Slag hardness, the lackof acid-generating p o t e n t i a l , and the absence of any sig-nif icant metals beneath the s lag also indicate that thepo t en t ia l for exposure to metals of concern found in thes lag is unl ike ly to change in the long term. Reuse of thes t o c k p i l e d f i n e s l ag would m a r g i n a l l y reduce any p o s s i b l eresidual risk because of volume reduction.

A C R O N Y M SAOC Adminis trat ive Order on ConsentARARs A p p l i c a b l e or Relevant and A p p r o p r i a t e

RequirementsC D P H E Colorado Department of Publ ic H e a l t h

and EnvironmentC E R C L A Comprehensive Environmental

Response, Compensation, and Liab i l i tyAct of 1980

CSM Conceptual S i t e ModelD & R G W Denver and Rio Grande Western

RailroadEPA U. S. Environmental Protection AgencyF S Final S t o c k p i l e d Fine S l a g F e a s i b i l i t y

S t u d yOU3 Operable Unit 3PRP Poten t ia l ly Responsible PartyRI Remedial Inve s t iga t i onR I / F S Remedial I n v e s t i g a t i o n / F e a s i b i l i t y S t u d yROD Record of DecisionNCP Nat iona l Contingency PlanNPL National Priorities Listppm parts per mi l l i onSARA S u p e r f u n d Amendments and

Reauthorization Act of 1986S F S S i t e - W i d e Screening F e a s i b i l i t y S t u d y

G L O S S A R Y

Action Level: In the S u p e r f u n d program, the level ofcontaminant concentration in the environment high10

enough to warrant action or trigger a response underC E R C L A / S A R A and the NCP.Admini s t ra t iv e Order on Consent ( A O C ) : A legalagreement signed by EPA, the p o t e n t i a l l y responsibleparty (PRP) for a site, and sometimes the state. Under aConsent Order, the violator agrees to pay for correctionof violations, take the required corrective or cleanupactions, or refrain f rom an activity. It describes the actionto be taken and can be enforced in court.Admini s t ra t ive Record: A f i l e that is maintained, andcontains all information used, by the lead agency to makeits decision on the selection of a response action underCERCLA. T h i s f i l e i s made available for pub l i c reviewat one or more information repositories near the site. Ad u p l i c a t e f i l e is held in a central location, such as an EPARegional O f f i c e .A q u i f e r : An underground geological formation or groupof f ormat ions containing useable amounts of groundwa-ter that can s u p p l y well s or springs.Arsenic: A grayish white element found natural ly in theenvironment. It is a byproduct of copper, zinc, and leadsmelt ing. Doses taken over long periods can cause birthd e f e c t s and genetic damage in test animals; there is evi-dence that it can cause skin and lung cancer in humans.Ballas t: Gravel or broken stone laid in a railroad bed orused in making concrete.Baseline Risk Assessment: A CERCLA s tudy conduct-ed at the same time as the remedial invest igation (andcontained in the RI/FS repor t) that determines and evalu-ates risks that site contamination poses to p u b l i c healthand the environment in the absence of remedial action.Comprehensive Environmental Response, Compen-sation, and L i a b i l i t y Act ( C E R C L A ) : A f ed era l lawpassed in 1980 and m o d i f i e d in 1986 by the S u p e r f u n dAmendments and Reauthorization Act (SARA). It setsup a program to i d e n t i f y s i te s where hazardous substancehave been, or might be, released into the environment andto ensure they are cleaned up.Conceptual S i t e Mode l: A process in which in format ionabout waste sources, release mechanisms, exposure path-ways, and receptors at or near a site is used to d e v e l o p aconceptual unders tanding of the s i te, in order to evaluatepotent ial risks to human heal th and the environment.

Consent Decree: A legal document, approved andissued by a j u d g e , that f o rmal i z e s an agreement reachedbetween EPA and p o t e n t i a l l y r e spons ib l e parties (PRPs)where PRPs will p er f orm all or part of a S u p e r f u n d sitec leanup. The consent decree describes actions that PRPsare required to perform.F e a s i b i l i t y S t u d y : A CERCLA s tudy which i d e n t i f i e s ,screens, compares, and evaluates d i f f e r e n t alternatives forcleaning up site contamination.Heavy Metal s: A group of chemical elements character-ized by their a b i l i t y to conduct e l e c t r i c i ty and heat.Exposure to some heavy metals can have toxic e f f e c t s onthe body and can cause adverse impact s on f i s h and otheraquatic communities. H e a v y metals can be h i g h l y toxicat r e la t iv e ly low concentrations.Human H e a l t h Risk Assessment: The portion of thebaseline risk assessment that addresses po t en t ia l risks tohuman receptors at or near the site.I n s t i t u t i o n a l Controls: A legal and enforceable restric-tion or agreement that enhances and complements thepermanence of a c l eanup remedy. Example s are laws, andzoning, land use, and deed restrictions.Leachate: A l iqu id re sul t ing when water, such asstormwater or rainwater, c o l l e c t s contaminants as it trick-les down through wastes or contaminated soil.Lead: A metal that is hazardous to h ea l t h , if breathed orswallowed. Its use in gaso l ine , pa in t s , and p l u m b i n gcompounds has been sharp ly curtailed or restricted byf e d e r a l laws. C h i l d r e n le s s than six years of age are con-sidered the most s u s c e p t i b l e to lead poi soning. Leadaccumulates in the body, and exposure to low l eve l s oflead over long time p e r i o d s may cause brain, bone, ornerve damage or learning d i s a b i l i t i e s in chi ldren.National Oil and Hazardou s Subs tance s P o l l u t i o nContingency Plan (NCP): The f e d e r a l r egula t ion thatguide s the C E R C L A / S A R A program.Parts Per M i l l i o n ( p p m ) : A unit of measure used toexpre s s very smal l concentrat ions of contaminat ion ins o i l , s ed iment s , water, air, or other media.Proposed Plan: A document requesting pub l i c input ona propo s ed remedial a l t ernat ive .

Record of Decision: A document which is a consol idat-ed source of in format ion about the site, the remedy selec-tion process, and the se lec ted remedy for a c l eanup underCERCLA.Release Mechanism: The means by which a contami-nant can be released from a source of contamination.Example s include s p i l l s , soil disturbance, or leaching togroundwater.Remedial Inves t igat ion: A s tudy conducted to i d e n t i f ythe t y p e s , amounts, and locat ions of contamination at af a c i l i t y . It also evaluates p o s s i b l e risk to pub l i c heal thand the environment from exposure to contamination.Resource U t i l i z a t i o n : The use of certain waste materi-al s , such as f i n e s l ag s , for commercial purpos e s such asaggregate in concrete or b a c k f i l l material.Screening of Alternative s: During the f e a s i b i l i t y s tudy,alternatives are evaluated to v er i fy that they are protec-tive, meet regula tory requirements, and are i m p l e -mentable.S l a g : T h e s o l i d , n o n m e t a l l i c , g l a s s l i k e byproduc t formedin a blast furnace or smelter when mel t ing metal s orreducing ores. S l a g f l o a t s as a l iquid on top of theprocess, and a f t e r it is cooled and s o l i d i f i e d , may be usedas an aggregate in concrete or for other purpos e s such asb a c k f i l l .S m e l t e r : A f a c i l i t y in which ore is s m e l t e d , that is, melt-ed in order to separate out the metal.S u p e r f u n d A m e n d m e n t s and Reauthorization Act( C E R C L A ) : M o d i f i c a t i o n s to C E R C L A enacted onOctober 17, 1986.T a i l i n g s : The portion of mineral ores that is separatedout during the m i l l i n g of ore and d i s p o s e d .T r a n s p o r t Pathways: The means by which contaminantmigration may occur once released f rom a source of con-tamination, for e x a m p l e via windblown dust or surfacewater r u n o f f .

11