DERR-2024-006854

EPA/ROD/R08-98/078
1998
EPA Superfund
Record of Decision:
MURRAY SMELTER
EPA ID: UTD980951420
ou 00
MURRAY CITY, UT
04t0U1998
EPA 541-R98-078
<rMG SRC 980780>
MT'RRAY SMEIJTER
PROPOSED NATIO}dAI, PRIORITIES LIST SITE
I{T'RXAY, IITAII
RECORD OF DECTSION
CERCLIS ID UrD98095l-420
1. Site Name and tocatsion'
The Murray Smelter Site ("the Sitelr) is located in the city of Murray, Utah, in Salt Lake County as
illustrated on Figure 1. The Site includes the former operational areas of the Murray Smelter and
adjacent Germania Smelter which are referred to as the "on-facility', area, as weII as surrounding
residential and commercial areas where airborne emissions from the smelters impacted the environment or
where contamination in shallow ground water may be transported in the future. These surrounding areas are
referred to as the "off-facility" area.
The on-facility area is approximat.elv l-42 acres. Its boundarj-es are 53oO south Street to the south, State
Street to the east, Little Cottonwood Creek to the north, and the west set of Union pacific railroad
tracks to the west. The off-facil-ity area is approximately 30 acres to the west of the on-facility area,
approximately 1.05 acres south and souEheast of the on-faciliuy area, and a small area between 5200 South
Street and Litcle cottonwood creek to the east of the on-facility area. The west, portion of the
off-facility area is bor:nded by Little Cottonwood Creek co the north, 3oo west street to the west, s3oo
South street to the south, and the on-facility boundary to the east. The south/southwest portion is
bounded by 5300 South Street to the north and Wilson Avenue to the south. The off-facilj-ty boundaries
r.rere determined by EPA based on the results of air dispersion modeling performed in November, 1994. The
purpose of the modeling lras to identify t.he area that potentially would have received the greatest amount
of deposition resulting from lead and arsenic emissions from the Murray Smelter during it.s operating
period.
For environmental sampl-ing, risk assessment, and risk managemenu purposes, the site was divided into
smaller areas to represent reali-stic areas of human and ecological elrposure. The 142 acre on-facility
area was divided into eleven "exposure unitstr (EUs) and the 136 acre off-facility area was divided intoeight "initial study zonesrr (fSZ's). The riparj-an area along Lj.ttle Cottonwood Creek was delineated as
the ecological study area. The Site boundaries, EU's, and ISz,s are shown on Figure 2.
2. Operatsioaal History
The Germania Smelter was built ln 7872 on the north west corner of the on-facility area adjacent toLitt1e Cottonwood Creek. The Germania Smelter processed lead and silver ores. Asarco bought the Germania
Smelter in 1899 and operated it until 1902. At the time, Asarco was also constructing the Murray Smelter
on property tso the south and adjacent to the Germania Smel-ter. In 1902, operations at Germarria stopped
and the Murray Smelter began operating and continued processing lead and silver ores until l-949. Smelting
operations produced a variety of by products including arsenic (as sulfates/oxides in flue dust or as
arsenic trioxide), matte (an iron sulfide matrj-x with high lead and copper content), arsenical speiss (anj-ron-arsenic-sulfide matrix), and slag (a viLrified iron silicate) .
The on-facility portion of the Sit.e includes both the former Germania Smeltser and Murray Smelter facility
areas. Minimal specific informatj-on is availabl-e on the smelter operations at the Germania facility.
After operations ceased, the area was regraded with Germania slag and, Iater. with slag from the Murray
Smelter. Subseguently, no significant historical features of the Germania Smelter remain and thedescription of smefter operations provided below is based so1e1y on descriptsions of the Murray smelter.
At tshe time of its construction, the Murray Smelter was reportedly the largest primary lead smelter in
the world. In addition to lead, several byproducts were al-so generated including go1d, silver, copper,
antimony, bismuth, arsenic, and cadmium. The main blproducts by voJ-ume were slag, arsenic and cadmium.
Fig:ure 3 is a layout of the Murray Smelter facilities. The Murray smelter incfuded an extensive rail
network, two stacks (330 feet and 455 feet high), eight blast furnaces, roasters, arsenic kitchens,
sinter plants, mi11s and power houses. The facility also inc]uded a baghouse for emissions control. Mostof the Murray SmeLter facilities have been demolished, except for the smelter stacks, some building
foundations, and the original office/engine room building.
A flow sheet for Murray Smelter operations for a920 is shown in Figure 4. Although modifications occurred
during the period of operation, the fundamental- processes remained the same. The raw material, lead ore,
was shipped from varj-ous locations and was classified either as sulfide ore or oxide ore. Oxide ore was
capable of being smelted directly, whereas sulfide ore reguired a preliminary, roasting step to reduce
the sulfur content. The primary manufacturing process was therefore characterized by two major
operations: (1) roasting operations to lower the sulfur content of sulfide ores and to produce sintered
material suitable for final smelLing; and (2) smelting operat.ions to produce lead bultion (shipped away
for final refining), maLte (sent to the roasters to be treated again by oxidation of its sulfur), and
sIag. The secondary manufacturing process \^/as the re-processing of flue dust and baghouse dust to produce
arsenic trioxide.
2.1 Roasting Operations
Prior to 1920, roasting operations involved three furnace types: (1) four Wedge roasters, (2)Dwight-Lloyd
roasters: and (3) five Godfrey Roasters, operated in conjunction with t,$/enty-seven Huntington and
Heberlein (nH&Hu) pots.
The Wedge roasLers received charge consisting of sulfide ore, matte from the blast furnaces, lead
concentrates from various points, and silica. These furnaces produced roasted ore which was then loaded
into tram cars and conveyed to cooling bins where it was combined with low sulfur ores and charged to the
Dwight-L1oyd roasters. Air emissions from the Wedge furnaces passed directly into a dust chamber that ran
along the north side of the Wedge roaster buildi.ng and connected the main roaster flue to the Cottrell
P1ant. The Dweight.-L1oyd roasters, or si-ntering machj-nes, produced material which was transferred
directly into rail cars and sent to t.he roast bins where the blast furnace charge was made up. Air
emissions from Lhe Dwight-Lloyd roasters were also sent to the Cottrell P1ant.
The Cottrell Plant was an electrostatic precipitator. Precipitated materials fell or were shoveled
directly into rail cars. These materials were either returned to the roasters or sent to the briquetting
plant to be brj-quetted for charging to the blast furnace. Gases from the Cottre11 Plant were sent to the
455-foot stack, which began operating in May 191-8. During repairs or other activities on the baghouse,
the roaster flue and treatment process received blast furnace gases.
The Godfrey Roasters were used to process flue dust from the baghouse and Cottrell P1ant.. Flue dust was
roasted in the Godfrey Roasters and the resulting arsenic trioxide vapor was conveyed to the arsenic
kitchens where it was collected as rel-atively pure arsenic trioxide. Exit gases from the kitchens were
sent to the western portion of the baghouse and coll-ected dust was recycled to the Godfrey Roasters.
Arsenic trioxide was stored in one of two concrete storage bins before transportation offsite for sale as
a product. In 7942, additions were made to the arsenic kitchens to increase their production capacity(additional kitchens were added) and to provide addj-tional storage (new storage bins for arsenic product
were installed) and conveyance capacity (a system to convey baghouse dust to the kitchens was installed).
2.2 Smelting Operations
Smelting was achieved by eight blast furnaces. The charge to the blast furnaces included oxide ore, flux
mat.erial, and roasting products. Air emissions were sent to an enlarged fIue, along the west si-de of the
building. From this chamber, the gases passed to a rectangular brick flue, 1"8 feet wide by 12 feet high,
which 1ed to the baghouse. Exit gases from the baghouse were usually sent to the 330 foot stack, although
gases from the baghouse or blast furnace were occasionally routed to the 455 foot stack. The baghouse,
installed in l-907, was constructed of brick 216 feet long and 90 feet wide, and contained approximately
4,000 woolen bags, each 30 feet in length and 18 inches in diameter. In 1920, t.he baghouse was divided
into four compartments, three of which were operated while the fourth was cleaned out. Dust from the
baghouse was either loaded into raj-1 cars for transport to temporary storage areas near the thaw house
where it was kept prior to off-site transport or conveyed to the Godfrey Roasters and arsenic kitchens by
narrow gauge railway for production of high-grade arsenic trioxj-de. The material from the baghouse was
low-grade arsenic oxide, which contained lower amount.s of arsenic than the arsenic kitchen product, with
arsenic present in oxide and sulfaLe forms. Prior to off-site shipment, arsenic kitchen product was
stsored j-n a wooden arsenic sEorage bin to the sout,h east. of the thaw house.
2.3 Materials Used/Generated by tbe Smelter Operaton
The conLaminants of concern to human hea]th at the Si-te are lead and arsenic 1. Based on the data
generated at t.he Site and information on historic smelter operations, elevated level-s of arsenic and l-ead
at the Site can reasonably be attributed t.o the following materials:
Lead Ore: No analytical data are available to describe the range of arsenic and lead
concentrations in ore matenials processed at the smelters. Lead contenLs for ore from ULah
were reported between 4.4 and 32 percent by weight. Ore mineralogy was variabl-e. but may
have included: galena, pyrite, arsenopyrite, sphalerite, anglesite, cerussite, and lead
oxide (massicot) .
Blast Furnace Products/By-products. Four mat.erials were typically generated during blast
furnace operation: metallic lead, speiss, mat.te, and slag. The materials would separate due
to their varing densities. Metallic lead was the primary product of the operatj-on, and it is
not elq)ected that any quantity is currently present at the Si_te.
Matt.e/Speiss: fn smeLting of ores at the Murray Smelter, the amount of speiss
produced was too smaLl to separate it from the matt.e. Matte/speiss generated in the
blast furnaces was comprised of metal sulfides, with iron being the dominant metal.
Analysis of speiss for various smelt.ers in the s/estern U.S. show lead contents
between 0.5 and 2 percent and arsenic contents between 31 and 32 percent. Anal-ysis of
matte at t.he same smelters show lead contents between 8.5 and 18 percent and arsenic
contents below detection limits. Since speiss contents were probably sma1] at Murray,
it is bel-ieved that any material present at Lhe Site will- contain higher ]evels of
lead than arsenic. Lead matte/speiss concentrate was stored out in the open in the
northern plant area.
Slag: Slag is an amorphous, vit.rified furnace product and the primary byproduct of
the smelting process. Air-quenched slag was the material- generated in the highest
volume by the smelter process and significant quantities are st.ilI present at the
Site. Lead concentrations of 8,200 to l-5,OOO miJ-ligrams per kilogram (mg/kg) and
arsenic concentrations of less than 5 to 1,500 mg/kg have been measured in slag from
the Site (both Germania and Murray slag piles). Metals are not typically released
from slag under normal environmental condi-tions. A series of leaching tests $ras
performed on a sample of slag materia] collected from the Site. The details of the
Ieaching tests and the resul-ts are summarized in the final Feasibility Study. The
tests indicate that a minimal proportion of the metal-s present is released from slag
when precipitation and gror..rnd water are the leaching solutj-ons. However, the release
of arsenic appears significantly enhanced at both extreme high and 1ow pH.
Flue Dust: Roasting'and furnace operatj-ons had a tendency to volatilize arsenic. These gases
were col-lected and transported in flues to treatment unj-ts, the Cottrell Plant or the
baghouse. Exit gases from these units were sent to the stacks. Flue dust is present in areas
where operations were ]ocated (f1ues, the arsenic kitchens, the Cottrel] plant, and the
baghouse) and in areas where flue dust was managed (next to the thaw house). Similar
materials are also present at the ground surface over a wj-der area. This is due to
dispersion resulting from spillage during material- handling, and stack emissions. Arsernic
leve1s in flue dust hawe been measured at 25,000 mg/kg.
Arsenic Trioxide: Arsenic trioxide was produced primarily during the processing of flue
vapors from the Godfrey Roasters in the arsenic kitchens. The material was probably in a
relatively pure form, with arsenic primariJ-y present in oxide forms and some sulfate
present. Elllre arsenic trioxide has been measured at 750,000 mg/kg arseni-c. Approximately
2000 cubic yards of arsenic trioxj-de have been found in the on-facility area of the Site.
Stack Emissions: Exit gases from the baghouse and Cottrell P1ants were routed to the stsacks.
Stack emissions resulted in the deposition of lead and arsenic onto surface soils in the
off-facility area. These emj-ssions occurred during the entire period of smelter operation.
Lead leve1s in off-facility soils impacted by stack emissj-ons have been measured as high as
1800 mg/kg. Arsenic l-eweIs in these soils have been measured as high as 610 mS/kg.
1 As will be discussed in subsequent sect.ions of this RoD, contamj.nants of concern
receptors within the ecological study area include other metals in addition t.o lead
However, the majority of the Site is sufficientl-y characterized by focusing on 1ead
to ecological
and arsenic.
and arsenic.
2.4 Smelter Demolition
Records indicate that as part of the shut down of the Murray Smelter, existing raw material feed stock
was processed and t.he resulting products and by-products were collected and sold. Due to this seguenced
shut down, the amount of residual raw material-s, products, and by-products l-eft at the Sit.e is limited.
The exception is slag, the primary by-product of the smelting process, whj-ch was initially present over a
large area. The initial quantity has been significantly reduced by mining in the period since the smelter
shut down.
The majority of smelEer structures were demolished in the period immediately after operations ceased in
1949. Based on envj-ronmental- sampling and histori-cal photographs, it appears that demolition of the main
smelter structures was conducted in an organizedmanner. Salvageable materials (e.g., metal- from the
processing units and rail J-ines, and other process eguipment) were taken off-site, and building
structures were subsequent.ly demolished with the brick and concrete debris typi-ca11y spread in the
immediate area. Slag was then brought in from the slag piLe area to cover the debris and t.o provide a
suitable surface for subseguent development of commercial/manufacturing operat.ions. Today, smelter
materials are typically present within the upper three feet below the current ground surface, primarily
in the form of slag brought in for fil1, residual materials such as flue dust within footprints of former
operations and mixed structural debris from smel-ter demolition in the immediate vicinity of former
structure locations. At a limited number of locations, relatively high level-s of arsenic such as that
associated with flue dust are present as deep as l-0 feet. This is thought to be Lhe result of dissolution
and transport by surface water infiltration.
Several smelter structures remained after the initial demolition activities. Some of the structures were
used as storage buildings until around 1980 when they were demolished as part of Site development. A few
structures, including the engine house and the stacks, are still present today.
3. Site Description
3.1 Land Use
3.1.1 Current Land Use
The on-facility area is currentl-y zoned Manufacturing General Conditional, M-G-C. This zoning designation
al1ows light industrial processes to be conducted with heavier industrial uses allowed after a
conditional- use permit. has been approved by Murray Cit,y. The majority of the on-facili-ty area is owned by
the Buehner family and leased by a concrete manufacturing company; the unrelated Buetrrer Corporation. The
company makes pre-cast and pre-stressed concrete building and transportation products as well as
architectural concrete products. other uses within the on-faculty area include a pipe warehouse and
distribution facility, the W.R. white Company, a telecommunications equipment company, Skaggs
Telecommunication Services,' a Federal Express outleti the Murray City Po1ice Training Facility; a
portland cement transfer and supply facility, Ashgrove Cement; other warehouses; and an abandoned asphaltplant owned by Monroe, Inc. There are two residential trailer parks within the on-facility area. The ,Doc
and Dell's" trail-er park is located on State Street. The "Grandview'r trailer park is on the southwest
corner of the on-facility area on 5300 South Street. The locations of these trailer parks are noted on
Figure 2.
Land use in the off-facility area is mj-xed residential/commercial. The western portion of the
off-facility area is currently zoned M-c-C and Commercial Devel-opment Conditionat, C-D-C. C-D-C Zoning
provides areas where a combination of businesses, commercial, entertainment and related activities may be
established and maintained. The southern portion of the off-facility area is currently zoned M-G-C and
1ow density single family residential, R-1-8. The Murray Junior High School and the Murray High School
are Located in the south portj-on of the off-facility area.
3.1.2 Future Land Use
rl 1997, the Murray City councj-l- adopted a land use plan for future development of the on-facility
portion of the Site and amended its General Plan accordingly. The land use plan for the on-facilj.ty area
includes construct.ion of a north-south roadway corridor from Vine Street to 5300 South Street through thecentral portion of the on-facility area. Murray City council has appropriated the funding for the road,
which extends north and south of the Site along the alig-nment shown in Figure 5. This afignment takesinto account the City's desire for traffic volume and the owners' desire for sufficient access. Largely
due to the construction of this access road, a significant portion of the on-facilicy area is highly
Iike1y to be redeveloped in the near future. Current land owners are discussing options with the City andpotential dewelopers to optsimize future use of the area. Much or all of the out.door industrial actsivityis expected to end, to be replaced with light. industrial/ commerciaL activities. The City will rezone t.he
area to C-D-C use by passing an ordinance establishing an "overlay district" which restricts cert.ain uses
and requires city review of development plans within the on-facility area boundaries.
Also, all residential occupation within the on-facility area will soon end. A Site developer has acquired
an option to purchase the Doc and De1l's trailer park with the intention of converting the trailer park
to commercial uses. Grandview Trailer Park has been purchased by the Utah Transit Authority (il"IA) and
residentiaL leases are not being renewed. UTA intends to swap the Grandview parcel for a parcel of land
owned by the Buetrner family near Ashgrove. Within two years, UfA will construct a light rail stationplatform adjacent to the exist.ing railroad tracks along with associated off-street parking, and
landscaping. If the land swap with BueLrrer occurs, then residential occupation of Grandview will be
termj-nated more rapidly as the site is developed. In either case, residential occupation of Grandviewwill 1ike1y end within two years.
The Amendment to the General Plan for Murray City also incl-udes three other potential public use
proj ects :
1) Murray City Court/Poli-ce Administrative Office. There is interest in locating a court/police complex
somewhere south of Little Cottonwood Creek, and south of Vine Street. The City will be establishingits own court system within a few years and will ultimately need facilities to be constructed forthis purpose. There is an urgent need to provide adequate police facil-ities as well as additional-
space in City Ha11. It is anticipated that three to five acres will be needed for this facility.
2l Little Cottonwood Creek Parkway Improvements. The Murray Parks & Recreation Department is interestedin obtaining property to enhance the south side of LiLtle Cott.onwood Creek with landscaping, a
walking and bicycle trail, urban p1aza, pavilion and restroom facifities contained within
approximat.ely 5 acres. This would a11ow the extension of the City's exist.ing trail system with atarget of connecting to t.he ,fordan River trail system.
3) Smelter Site Interpretive Park. There is also interest i-n developing a sma11 interpretive park at the
base of the smelter stacks that would be no larger than approximately two acres. The small park couldcontain a p1aza, seating, founlain and landscaped areas. Historical information relating to the
smel-ter Site history would be integrated into the park development.
This type of development provides the opportunity to integrate implementation of remedial actions i_nto
development activities, a key objective of EPA's Brownfj-e1ds Program. Gi-ven the interest in developingthe on-facility area and the high 1eveI of involvement and cornrnitment by the City of Murray and thecurrent land owners, there is sufficient certainty concerning, future land use to identify the reasonahlyanticipated future land use scenario as recommended in the EPA OSWER directive ',Land Use in the CERCLA
Remedy Selection Process". The reasonably anticipated future land use for the on-facility area is Ii_ghtindustrial /commerciaL use .
rn the off-facility area, areas to the vrest of the on-facility area (fsz-l and fSZ-8) are zoned M-G-C and
C-D-C but do have some residential- occupation. This zoning prevents the const.ruction of new homes, andtherefore, residential occupat.ion is expected to end in the future. To the south of the on-facility are(rsz-6 and rSZ-7) a portion of the land is zoned for residential use and a portion is zoned M-G-c.Similar to the western off-facility area, although there are some exj-sting non-conforming residences,residential- occupation is elq)ected to end sometime in the future due to the prohibition of new homeconstruction and the redevelopment of the on-facility area. The reasonably anticipated future land usefor the off-facil-ity area is a combination of commercial/light industriaL and residential.
3.2 Topograpby
The Site is mainly fLat in the southern portions. Near Little Cottonwood Creek on thenorth, the terrain slopes steepfy. This area used to be filled with slag from the Murray Smelter butover the years since the smel-ter shut down, the slag has been excavated and used throughout thesalt Lake va11ey. A steep wa1l of concrete debris from recent site uses and residual slag remainsin the northern area where slag used to exist..
3.3 Geologic Unitss ..d Soils
The geologic units at. the Site consist pri.marily of lake sediments from pleistocene Lake Bonneville,
however, younger alLuvial floodplain deposits are for.:nd along Little Cottonwood Creek. The lake sedimentsconsist of cIays, sil-ts, and fine sands and r:nderlie the more recent all-uvial stream deposits whichgenerally consist of siLt, sand, and gravel. surface soils within ttre on-facility portion of the Site
have been disturbed, affected by the const.ruct.ion and operation of smefting, ore handl-j-ng, and refiningfacilit.ies over a period of 77 years. In more recent times, construction and operation of concrete,
asphaLt, and other commercial or manufacturing facil-ities have further disturbed the area's soils. In
particul-ar, construction of the facilities and the deposition of slag from smelting operations and other
fill materials have covered the majority of the origina)- surface soils.
fn the off-facility area, surface soils have been significantly affected by extensive general urban
development.
3.4 Hydrogeology
The Site lies on an area covered by thi-ck valley-fj-I1 (a1l-uvi-al) deposits that comprise several distinct
aguifers within the aguifer system. Specific components of the aquifer system are as follows:
. sha]Iow Aquifer: a shaI1ow, unconfined aquifer comprised of interbedded sandy clays and
clayey sands occurrj-ng above the Bonneville Blue CIay;
o Bonneville Blue Clay: approximatel-y 3O-foot-thick cont.inuous layer of clay separating the
shallow and intermediate aguifers;
. fntermediate Aquifer: a confined aquifer immediately underlying the BorlIleville BIue CIay
comprising approximately 10 to 20 feet of relatively coarse-grained deposits; and
. Deep Aquj-fer: an artesian aquifer, several- hundred feet below the intermedi-ate aquifer,
comprising various coarse-grained valley-fiI1 deposits
The shallow aquifer is unconfined with a saturated thickness that ranges from 2.5 to 25 feet within the
on-facility area. The average depth to water is approximately l-o feet, The aquifer materials have a
geometric mean hydraulic conductivity of 5 feet per day (based on esti-mates from different locations in
the study area ranging from 1 to 1l-2 feet/day). Groundwater in t.he shal-Iow aguifer flows along the top of
the Borureville BIue CIay, generally north-northeast, toward Little Cottonwood Creek as shown in Fi-gure 5.
Water levels measured adjacent to the creek indicate that the shallow aquifer is hydrauli-caIly connected
to Little Cottonwood Creek and that groundwater discharge to the creek occurs during certain tj-mes of the
year.
The second component of the aguifer system is the Bonneville Btue C1ay. Available hydrogeologicj-nformation indicates that the Bonneville Blue Clay is continuous across the facility and the surrounding
area. This lithologic unit forms an effective barrier for vertical groundwater movement from the shallow
aguifer to the intermediate and deep aquifers. Analyses presented in the Feasibility Study support this
conclusion.
Beneath the Bonnewille Blue C1ay, the intermediate and deep aquifers are separated by more than 2OO feet
of interbedded fine- and coarse-grained va11ey-fi11 and altuvial deposits. Both receive rechargeprimarily up gradient of the Site. Groundwat.er in the intermediate aguifer flows north-northwest across
the Site as shown in Figure 7, and the aguifer is not hydraulically connected to surface water bodies in
the vicinity of the Site. The deep aquifer j-s the main source of drinking water for most resident.s in the
Salt. Lake Valley. Municipal water-supply weI1s located in the vicinity of the Site are screened more than
500 feet be1ow the ground surface in the deep aquifer.
3.4.1 Potential for Use of Ground Water as a Drinkinq Water Supplv
rt is unlikely that the shalfow aquifer will ever be used as a potable water supply due to several
conditions. Primarily, t.he water is of poor guality for drinking water. Background total dissolved solids
(TDS) concentratj-ons range from 505 to 3,236 mg/L and exceed EPA's secondary drinking water quality
standard of 500 mg/L. Additionally, this water supply is only availabl-e in timited quantity due to the
aquifer thickness coupled with 1ow hydraulic conductivities which do not produce sufficient water for
typi.cal water suppl-y needs. The intermediate and deep aquifers provide lower TDS and higher yielding
water supplies. However, within EPA's ground wat.er classification system, two factors are considered in
designating ground water as a potential- drinking watser sourcei waLer qua]ity and yield. fn EpA's
regulatory scheme, water is considered to be suitable for drinking if it. has a mS concentration of l-ess
than 10,000 mg/L and either can be used without first being treated or can be rendered drinkable after
being treated by methods reasonably employed in a public water supply system and can sustain a yield of
150 gallons per day. The characteri.stics of both the shall-ow aquifer and the intermediate aguifer at theSite meet EPA's criteria for designation as a potential drinlcing water source, Cl-ass Ifb and Utah's
criteria for designation as a Class II drinking waLer under Utah's Gror:nd water Qual-ity protection Ru1e.
The deep aquifer meets both EPA's and Utah's criteria for designation as a Class I aguifer, a currentdrinking water source.
3.5 Surface Water
Little Cottonwood Creek is a perennial stream flowing along the north/northeast boundary of theon-facilicy area and into t.he ,Jordan River approximat.ely one mile downstream. The stream has been altered
by urban and agricultural development both upstream and downstream of the Site. In the nort.hern portion
of the on-facility area, the course of the stream was altered duri-ng smelter operation. FaciU-ty drawings
and aerial photographs indicate that. the creek originally flowed through the northern portion of theon-facility area, but during smelter operation the creek was diverted to the north with the former
channel incorporated into the slag pi1e. Today, the upstream reaches of the creek are bordered byresidential areas or parks, while the Sj-te and downstream reaches are mainly bordered by
commercial/industrial areas.
Historically, Little Cottonwood Creek has been stocked with rainbow trout and German broern trout.i
however, reproductive success of these fish is thought to be poor due to the steep gradient and a below
average availability of good quality pools in the creek. fn the vicinity of the Sit.e, Li-ttle Cottonwood
Creek is designated by the state of Utah for secondary contact recreation use such as boating and wading(crassification 28), for cold water game fish use (classification 3A) and agricurturar use(classification 4). A survey of Lj-tt1e cottonwood Creek conducted in 199T found no di-versions of surface
water for agricultural use downgradient of the Site. Although no formal petition has been brought forwardto the Utah water Quality Board to change the agricultural use designation, existing evidence documentedin the survey report suggests that such use is not 1ike1y in the future.
In addition to the use designations assigned by the state of Utah, fisheries habitat in Utah is
inventoried and classifj-ed on a state$ride basis by the Utah Division of wildlife Resources. The sectionof stream near the Murray Smelter has been desigrnated as a Class s stream based on esthetics,availability, and productivity as determined i-n a physical habitat survey conducted in 1974. According to
the classification system, class 5 streams are now practically valueless to the fishery resource, however
many r.raters in this class could provide valuab1e fisheries if sufficient guantity of water could beprovided.
on the northern area of the site, shallow gror:nd water within t,he floodplain of Little Cottonwood. Creek
surfaces at three distinct locations to form wetlands. An area of 0.75 acres of wet.lands were identifiedin a delineation study done j-n .rune, 1997 by Hydrometrics titled "Report of Wetland Determination, Littl-e
cottonwood creek Riparian Area, Former Murray smelter site, Murray, utah".
3.6 Climat,e
The Salt Lake area has a semi-arid climate. Average precipitation is approximately 1G inches per year andthe average air temperature is approximately 54 degrees Fahrenheit. The Site elevation is approximately
4280 - 4315 feet above sea leveI.
3.7 Floodplain
The most recent flood insurance study which includes r,ittle Cottonwood Creek was done by HUD in 1994.
Several differences have been observed between exist.ing floodplain topography and the floodplain cross
section data utilized for development of the most recent floodplain map. Existing conditions comparedr.rith conditions from which previous floodplain delineations were based, show more floodplain area in the
southbank (within the on-facility area) and l-ess flood plain was in the northbank (north of the Site
boundary) - The large existing southbank floodplain area probably resulted from excavation of slag fromthis area, or i-t may have been excluded from previous studies because it may not be part of the effectiveflow conveyance. Most of the site is outside of the 1Oo year floodplain as shown on F.igure 8 from the HUD
study.
3.8 Nearby Populations aad Demographics
Based on data from the 1990 census, approximately 2O,ooo people live within a mile radius of the site.
The majority of this population is non-minority. of the 20,000, there are approximat.ely 2,100 children 5years old or younger, 2,700 adults over the age of 50, and 4,200 women of child-bearing age (18-45 yearso1d). Figure 9 summarizes this demographic information.
4 Site Histsory aDd Eaforcefirent Activities
4.1 AdmiaigErative Order oD CoIrsenL for anr Eugineeriag Evaluation/Cost Analyaia
In ,January, 1994, EPA proposed that the Site be listed on the National priorities List. on August 5,
1994, EPA issued a letter of "Nouice of Potential Liability and Demand for payment to Asarco.
Negotiations between EPA and Asarco commenced shortly thereafter culminating in Septsemlcer, 1995 when EpA,
Asarco, and Murray City entered into an Administratsive Order on Consent (AOC) for the performance of an
Engineering Evaluation/Cost Analysis (EE/CA) for the Site. EPA ret.ained responsibility for performing a
baseline human health and ecological risk assessment for the Site. The EE/CA was intended to support. a
Non-Time-Critical removal action.
4.2 AOC for Time Critical Removal
On September 13, L995, EPA and Asarco entered into a separate AOC for conducting a time critical removal
at the playground area of the Grandview Trailer Park. The scope of this time critical removal was
excavation of soils wit,hin and adjacent to the playground which contained unacceptable levels of lead and
arsenic and backfill of those areas wj-th clean fj-11. This removal action was complet.ed by Asarco in
November, 1995. The removed soils have been temporarily stored j-n a waste pile on-Site and will be
consolidated on-Site as part of the remedia] action selected in this ROD.
4.3 Memora"adum of Understarding with Murlay City
In April, 1996, EPA and Murray City entered into a Memorandum of Understanding which established that
Murray City would assist EPA in identifying current and potential future land use at the Site, in
developing response action alternatives, and in implementing any institutional controls required by EpA,s
chosen response action.
4.4 EE/CA
Data needs were identified in the EE/CA Work p1an, an at.tachment to the EE/CA AoC. Environmental sampling
tso support the EE/CA and risk assessments began in April 1995. Asarco completed a Site Characterization
Report in August, 1995. Shortly thereafter, EPA decided to redirect what had been a Non-Time-Critical
Removal activity into the remedial action framework. Accordingly, the reguirement for an EE/CA was
changed to a Feasibility Study. Table 1 shows the completion dates for the major documents whj.ch support
thi-s Record of Decision (ROD).
Tab1e 1: Corrpletion Datea for Major Documeats Support,iDg the ROD
DOCUMENT RESPONSIBIIJITY COMPLETTON DATE
Site Characterization Report Asarco August, 199G
Baseline Human Health Risk EPA t'4ay, t99j
Assessment
Feasibility Study Report Asarco Aug.ust, 1992
Baselj.ne Ecological Risk EPA September, l-997
Assessment
Proposed Plan EPA Septenber, 1997
4.5 Iuformation Requesta
EPA sent CERCLA, l-oa(e) requests to Asarco and on-facility property orrners by leLter dated April 25, 7996
seeking information on operations at the Site and material handling and storage details. Responses to the
informat.ion requests were provided by all recipients.
5. Scope of Responge Action
The remedial action which is t.he subject of this ROD is t.he second of the t.hree response actions EpA
considers to be necessary at the Site. The first response action was a time critical removal of soils
located in and adjacent to the playground area at the Grandview Trailer Park. These soils were
contaminated with lead and arsenic at leveIs considered by EPA to be unacceptably high. The area wasbackfilled with clean fiIl. The decision to undertake the time critical removal action is documented in
an Action Memorandum signed by EPA Region 8 on November 7, 1995. Asarco completed the Grandview Trailer
Park time critj-cal removal actj-on in November, 1995.
The remedial action described in this ROD addresses contaminated ground water, t.he subsurface soil whichis the source of the ground water contamination, contaminated surface soils, and the surface water ofLittle Cottonwood Creek as follows:
a
1.Contaminated ground water. Source control will be implemented by excavation and off-site disposal of
the principal tshreat wastes at the Site. approximately 2000 cubic yards of residual undiluLed arsenic
trj-oxide. This material is considered a principal threat due t.o its high mobility and its demonstratedability to act as a source of Ground water contaminat.ion. In addition, direct contact with this
mat.erial may result in acute human health risks. F\-rrther source control will be implemented by
excavati.on of approximately 68,000 cubic yards of low leve1 threat rraste, dil-uted arsenic trioxide orflue dust mixed with soil, fiIl, or debris from former smelter structures. rhis material will be
consolidated within a repository system constructed within the Site boundaries. The repository will be
desj.gned as the base for a nerr, access road through the Site which was planned by Murray City. The
access road is elq)ected to be the catalyst for Site development. Monitored natural attenuation wi1l
address the residual gror,rnd water contaminat.ion within and down gradient of these source areas.Instj-tutional controls in the form of a Murray City ordinance est.abLishing an "overlay district,, andrestrictive easements that run with the land bot.h will prohibit the construction of new weI1s or useof existing wells (except EPA approved monitoring welIs) within the on-facility area and t.he western
and eastern port.ions of the off-facility area.
Contaminated surface soils. on-facility surface soj.1 containing leve1s of lead and arsenic which
exceed remediation 1evels will be covered. The barriers will provide protection by breaking the
elq)osure pathways associated with long term dj.rect contact with these soils. Site development. itselfis e>qrected to result in addilional protection of human health since Land uses associated with
unacceptable human heaLth risks will end. Also, the development will result in the construction ofadditional barriers (new buildings, roads, sidewalks parking lots, and landscaping) over remaining
surface soil and slag. Al-though no unacceptable risks associated with oq>osure to slag were idenEifled
by EPA, the development of Ehe site will ensure no e)<posure to slag in the future. rnstitutional
controls in the from of a Murray City ordinance will establish an "overlay district" which includes
zoning to prevent residential and cont.act intensive industrial uses within the former smelter
operational areas and will reguire maintenance of the barriers and controls or excavated subsurfacematerial within this same area. Restrictive easements that run with the land will be esta.blished inaddition to the overlay distrj-ct to prevent resident,ial or contact intensive industrial uses.
off-facility surface soils containing leveIs of lead exceeding remediati-on leveIs will be removed andreplaced with clean filI. The removed soil will be used on-facili.ty as subgrade material" inconstruction of the repository system.
Surface water. Little Cottonwood Creek, which forms the northern boundary of the Site and to whichshallow ground water discharges will be monj-tored to ensure continued protection during the ground
water natural attenuation process. Additional monitoring of the ecological study area of the Site will
be used to reduce the uncertainties identified in EPA's predictions of ecological risk.
3.
The remedial actj-on protects ground water and Litt.le Cottonwood Creek and incorporates the constructionof a new north-south access road through the site which will encourage future development of the Site andhelp achieve Murray Ci-ty's goal of more appropriate land use through sit.e development. Institut.ionalcontrols will prevent elq)osure of people to ground water wi.th arsenic concentrat.ions that represent an
unacceptable risk and will also ensure that future uses of the land will be protective and that the
remedi-ation will be maintained.
EPA elq)ecEs that an additional response action will be reguired at the site. A structural- analysis of theexisting stacks at the Sit.e was completed in .Tanuary, L998. The study concludes that both st,acks as theyexist today are not able to r.rithstand seismic events which are specified in the current Uniform Buj-Iding
Code- Based on information coLlected as part of Site characterizatj-on efforts on the nature and extent of
contamination on interior bricks of the stacks, EPA expects that an additional time critical removalaction will be requi-red to address the potentsial for release of hazardous substances and resultj-ng healthrisks associated with the potential structural failure of the stacks.
6. HighligbtE of Cqmllr[ity participation
EPArs community involvement activitsies at the Site began in March, 1995 wlt.h the establishment of theinformati-on repository at the Murray City Library. rn Augnrst, 7995, when the EE/CA work plan was in finalpreparation, EPA and UDEQ rel-eased a fact sheet describing the scope and objectives of the siteinvestigation. wj-th the assistance of Murray City officials, two public meetings were conducted on Augmst9, L995 and AugusL 10, 1995 to inform the affected citizens of Murray about Ehe up-comingr investigat1-onactivitsies on or near their property.
In septemlcer, L996, EPA released another fact sheet describing the preliminary results of the baseline
human health and ecol-ogical risk assessments. Since the results were specific to separat.e populations,
EPA conducted six separate public meeti-ngs and two availabili"ty sessions to explain the results of
environmental sampling and risk assessments.
In October, 1995, EPA iniciated the formation of the Murray Smelter Workj.ng Group consisting of
representatives of UDEQ, Asarco. owners of property and businesses on the Site, Murray City, and EpA. The
purpose of the Working Group was to inform EPA about pending Site development plans and to provide a
forum for discussing alternatiwe cleanup strategies for the on-facility area of the Site. In a series of
open meet.ings conducted during October, 1995 through February, l-997, implicaE.ions of remedial
alt.ernatives irere discussed by the working group. EPA provided information on the nature and extent of
contamination and the clean up requirements.
The following commitments erere made as a result of the Working Group sessions:
1. Current propert.y owners, Murray City, and Asarco are commj.tted to accomplishing the necessary tasks to
ensure t.hat a new road will be constructed on the Site between Vine Street and 5300 Sout.h Street.
These tasks include dedication of the land for the road right of way and agreement on the
establj-shment, of a "Special Improvement District" to fund utility construction.
2. Current property owners and Murray City are willing to work together to establish appropriate public
and private institutional controLs as required by EpA's selected remedy.
3. Asarco is willing to use its best efforts to design a remedial action that is consistent with the
Murray City General Land Use Plan.
The agreements among E.he mernlcers of the Murray Smelter Working Group are memorialized in an Agreement in
Principle signed in May, 1997.
In September, L997, EPA released the Proposed Plan for the Site and made available all supporting
documents in the j.nformation repository established at the Murray City Library and the EpA Superfund
Records center at the EPA Region 8 offices in Denver, Colorado. The notice of availability of these
documents was published in the SaIt. Lake City Tribune and the Deseret. News on September 23, L997. Apublic comment period was held from Septembet 22, 1997 until October 22, 7997. In addition, a public
meeting was held on October L, 1997. Responses to the comments received during the public comment period
are incl-uded in the Responsiveness summary which is part of this ROD. A summary of the highlights of
commr:nity part.icipation is presented j-n Table 2.
This decision document. presents the selected remedial acLion for the Murray Smelter Site in Murray, Utah,
chosen in accordance with CERCLA and the National Contingency Plan. The decision for this Sit.e is based
or the administrative record.
Talrle 2: HighLights of Comnuaity Participation Aclivities
ACTIVITY ST]BJECT DATE
Fact Sheet summary of site investi-gation August, L995
.activities
h:blic Meeting er<planation of sampling August 9-10, 1995
activities
Fact Sheet draft risk assessment release September, 1996
Pr:blic Meetings/Availability draft risk assessment and September, 1996
Sessions sampling results
Murray Smelter Working
Group Sessions
Fact Sheet
future site use plans and October, 1996 - February,
remediation alternaE.ives 1997
Proposed PIan of Action Sept.edber, 1997
h:bl-ic Meet.ing comments on the Proposed October, 1997
Plan
R-tb1ic Comment Period Proposed PLan of Action Septsember 22 - Oc|Lober 22,
)-997
7 Sumrnary of Site Characteriatics
7.1 Scope of Site Investigation Act,ivitieg
Using data available from Preliminary Assessment/Site rnvestigation actiwities. EPA performed screening
1evel calculations to identi-fy t.he chemicals of concern which would be the focus of site
characterization, risk assessment, and remedial activities at the Site. This analysis is documented inthe "Preliminary Scoping Report" prepared by EPA in December, 1994. The analysis concludes that Lead and
arsenic are the chemicals 1ike1y to be of substantial concern to humans. Based on these resul-ts, the
EE/CA work Plan specified lead and arsenic chemical analysis of soil and ground water samples collected
to support site characterization and the basel-ine human health risk assessment. Recognizing that
chemicals of concern to ecological receptors, especially aguatic organisms, often are different from
those of concern to humans, EPA selected the ecological chemj-cals of concern by evaluating historical
data collected from surface water, sediment, and soil in the Little Cottonwood Creek riparian zone. This
evaluation was done by the EPA Region 9 Ecological Technical Assistance Group (ETAG) at a meeting on
iranuary 31,, L995. rn addition to arsenic and lead, the ETAG identi-fied alumj-num, cadmium, copper,
mercury, nickel, selenium, silver, thallium, and zinc as ecological chemicals of concern to be
investigated in the ecologj-caI study area.
7.2 Soil aad DuEt. Investigatiorl
The site investigation for surface soil, subsurface soil, and dust is detailed in the Fina1 EE/CA Work
Plan completed in September, 1995. Prior to sampling. the on-facility area was divided into eleven ISz
based on current. property boundaries and land use. Similarly, the off-facility area was divided intoeight EUs based on consideration of the predicted pattern of historic air deposition from the site along
wit.h current street and land use features. A total of 10-20 surface soil samples (defined as 0,,-2" deep)
were collected from each on-facility EU. More samples were collected from the larger elq)osure units. Inaddition, test pits were excavated in several elq)osure r:nits, using existing and historical features to
select the location of the pits. Special emphasis was placed on areas where potential sources of
contamination such as hist.orical locations of the smelter flues, the bag house, waste transfer
facilities, the roasting areas, lhe arsenic kitchen, and the smelting areas t ere located. At each testpit, subsurface samples were collected in one foot intervals to a depth of 5 feet.
rn the off-facility area, surface soil samples were col-lected from L0 to 15 distinct residential yards
(depending on the size of the ISZ) within each ISz. Each sample was a composj-te of surface soil from 4 to
5 sub-locations within the yard. In addition, 16 soil borings were collected (two different locations in
each ISZ) and subsurface soil samples were collected from the On-2tr, 2"-6,n, 6"-!2" and 12"-19" intervals.
These subsurface samples were collected to characterize the vertical extent of contamination in eachoff-facility LSZ. Indoor dust samples were collected from 22 different homes or buildings in theoff-facility areas. Samples were collected using a hand held vacuum. T'ypica11y, each sample was a
composite of dust collected from three areas, each about 2 feet by ? feet. Summaries of sampling resul-tsfor soi.1 and dust can be for.rnd in Tables 3-5.
After the Baseline Human Health Risk Assessment was completed, supplemental soil sampling was conductedin every residential yard within those ISzs which were predicted to have unacceptable risk. A summary ofthis supplemental sampling effort can be found on Figures 10-12.
Table 3: Sunrnary Statistics for Indoor Dus! Samples
* OF SAMPLESCHEMICAL
Arsenic
Lead
AVERAGE
27 ng/kg
RANGE
s mg/kg - 9a mg/kg
2t 303 mg/kg 83 mg/kg - 7s7 mg/ks
In order to gain informatj-on on the physical and chemical nature of the lead and arsenic present in
surface soil, EPA collected 10 samples from locations on the Site. These samples were dried and sieved to
yieLd the fine fraction (<250 um) and submitted for geochemical characterization. The lead in soil at the
Site occurs in a wariety of different forms, most commonly as lead phosphates, lead silicates, lead
oxides, iron-1ead oxides, lead arsenic oxide, and lead su]fide. In contrast, arsenic occurs mainly as
ferric-Iead-arsenj.c oxide and lead-arsenic oxi-de with only small amounts of other arsenic species. The
lead and arsenj-c bearing particles were mainly smal1er than 20 um with abouts 8Ot of al1 the l-ead or
arsenic bearing grains exj-sting in a l-iberated or cemented st.ate, with only about 20? existi.ng within a
rock or gl-ass matrix.
7.3 SIag Investigat,ion
EPA coll-ected a si-ng1e composite sample of slag from nine different locati-ons at t,he site. Two of thesubsamples were from the Germania smelter slag pile, six rrere from the face of the slag monolj-th 1ocatedadjacent to EU-2, and one was from the slag at the base of the stag pile adjacent to Doc and DeII,strailer park- The composite slag sample was analyzed in duplicate using contract Laboratory program
methods- The mean vaLues of the duplicate analyses are 595 mg/kg arsenic and 11,500 mg/kg 1ead.
rn additj-on to chemical analysis, the slag sample was submitted for geochemical charact.erization. Asexpected, the principle form of lead-bearing partic1e in t.he sJ-ag sample is slag (i.e., particles ofglassy matrix with lead di-ssolved in the glassy phase). However, this type of particle contains arelatively 1ow concentratj-on of lead and so does not account for most of the 1ead mass in t.he sampre.Rather, the majority of the rel-at.ive l-ead mass exists in the form of fead oxide with smallercontributions from galena (9?), lead arsenic oxide (6?) ard other metal lead oxides (4?) . About g7Z ofafl lead bearing particles in the slag sample are liberated, accor:nting for about TTt of the relativelead mass.
Similarly, the most freguent. type of arsenic bearj-ng particle in the slag sample
62% of the relative arsenic mass. The majority of these particles are liberated,entirely outside the confines of glassy slag particles.
7.4 cround Water Inveatigation
Samples of surface water, sediment, benthj-c macroinvertebrates, and rj-parian soilecological study area and analyzed for ecoLogical chemicals of concern as part ofefforts - Figure L3 shows the locations of these samples. Summaries of the resultsfound in Tabl-es 7-10.
The ground $/ater investigation was conducted in two phases which included instal-lation of l-3 monitoringwells in the shatlow aquifer, 7 monitoring we11s in the intermediate aguifer (phase r), and a hydropunchinvestigation (Phase If). Several other on-facility wells that had been installed in earlierinvestigations were also redeveloped and sampled. A presentat.ion of the results of aIl- the ground watersampling performed between october, 1995 and Apri1, 1995 is contained in the final site characterizationReport' shall-ow alIuvial and intermediate around water continues to be monitored quarterly. Summaries ofthe sampling results for key analytes in shallow ground water can be found in Table 6. A full summary ofa ground water sampling results can be found in the october, 7997 Ground water and surface waterMonitoring Report. The most severe site-related impact to shallow ground $rater was found to be arseniccontamination- Figure 5 ilLustrates the arsenic 1evels detected in shallow gror:nd wat.er in January, 1996.District plumes of contamination can be seen i-n areas underlying the former locations of smelteroperations.
7.5 Surface Water, Sediment, and f,fp33frn SoiI lDvestigation
is s1ag, accoulting for
existing partially or
were collected in the
site charact.eri-zation
of this sampling can be
subsequent to site characterization efforts, additional quarterly surface water sampling was conductedbeginning in JuJ-y, 1996. Additional locations were established to characterize areas of Little cottonwoodcreek which receiwe ground water discharge from the shallow aguifer and to characterize the effects ofground water and point source discharges on the water quality of Little cottonwood creek. Figure 13ashows these additional- locations. This supplemental sampling was lj-mited to arsenic analysis. summariesof the surface water resul_ts can be found in Tab1e 11.
The results of the point source discharge sampring are particularly significant because they indicatethat the increase in dissol-ved arsenic concentrations in Little cottonwood creek occurs in the vicinityof the discharge from a storm sewer culvert running north along state street.. Loadi-ng calcu1ationspresented in the Apri1, l-997 quarterly monitoring report demonstrate that near]y aII of the dissolvedarsenj-c loading (88?-100?; accolmt.i-ng for fl-ow measurement accuracy) observed in the creek appears tooriginate from the curvert point source discharge. Gror:nd water discharge from the sharlow aquifer in theon-facilit'y area to the south of the creek was not shown to have a measurable effect. on arsenic l-oad inthe creek.
8. Suunary of Site Risks .-d Remedial Action Objectsives
8.1 Human Eealth Riska
EPA completed a baseline risk assessment for the Site in May, l-997. Human heal-th risks were calculated
separately for four groups of people to characterize risks for the current and reasonably anticipated
future land use; on- and off-facility residents; on-facility workers who spend most of the day indoors
(non contact intensive (NCI) workers); on-facility workers who spend most the day outdoors and are
engaged in act.ivities that result in significant exposure to soj.1 and dust (contact intensive (Cf)
workers); and teenagers who have been observed congregating in areas along Little Cottonwood Creek. The
exposure pathways evaluated for each group were ingestion of soil and dust., ingestion of slag (onIy
evaluated for current and future teenagers), and ingestion of ground water. Other erq)osure pathways to
site-rel-ated \.rastes are judged to be sufficiently minor that quantitative evaluation was not warranted.
The current land use for the site is a combinat.ion of commercial (best. represented by NCr Workers),
industrial (best represented by CI workers), and residential. As discussed in Section 3, the reasonably
anticipated future land use for the on-facility area is commercial/light industrial (NCI) and for the
off-facility area is a combination of commercial/1ight industrial (NCI) and residential. The exposure
assuq)tions used in the risk assessment were also used to develop preliminary remediation goals for soil.
These assumptions can be found in Appendix B.
The risk assessment, was performed using two distinct approaches for the on-facility and off-facilityportions of the sit.e. The majority of t.he on-facility was divided into seven EUs, sized to approximate
the area over which a typical office or industrial worker would come into contact with surface soifs
during a working lifetime. The residential trailer parks within the on-facility area were divided intofour smaller EUs sized to approximate the area over which a child or adult might come in contact withsoil during the period of residence. soil samples were collected within each e>cposure unit and averaged
according to EPA gnridance. This average, the "elq)osure point concentration',, was the basis for the risk
calculation. EPA will manage risks for the on-facility area by EU.
In contrast, the off-facility was divided i-nto eight. ISZs sized to represent neighborhoods, notindividual residences. This was because historical data indicated little variability in concentrations of
lead and arsenic within nei-ghborhoods. Concentrations in general tended to decrease with distance fromthe smelter site. The term rsz was chosen deliberately to refl-ect that the risk assessment for t.heoff-facility area is an "inj-tiaI" or screening level assessment. The e].posure point concentrations forthe off-facility risk assessment were the average concentrations for each ISz or neighborhood. EpA
esEablished the following decision rule for the off-facility: If the screening Ieve1 risk assessmentpredicts unacceptable risks in a given rSZ, the assessment will be refined (i.e., additional samples will
be collected to characterize each residence, exposure point concentrations will be established based onthese samples and will be compared to the remediation goal), if the screeni_ng l-evel risk assessmentpredicts acceptable risks in a gj-ven Isz, Ehat ISZ is considered to require no further action. Based onthis decision ru1e, additional soil samples were collected from each residence wit.hin rsz L,6, and 7.
The refinement of the screening level assessment was completed after this supplement.al soil sampling wasperformed in lSZs 1, 5 and 7 in.Ianuary, 1997. A comparison of these sampling results with ghe
residential remediation goals comprises the final risk assessment for the off-facility area. EpA will
manage risks for the off-facility area by individual yard.
8 .1. L Arsenic Risks
The risks associated with exposure to arsenic in soil are summarized in Table 12 excerpted from the final
Human Healt.h Baseline Risk-Assessment. Current EPA policy, summarized in oSwER Directive 9355 o-30,states that where the cumulative carcinogenic site risk to an individual based on the reasonable maximum
exposure for both current and future land use is less than l-O -4, and the non-carcinogenic hazardquotient is less than 1, act.ion is generally not warranted. Using this criteria, the cancer and
non-cancer risks associated srith the reasonable maximum exposure to arsenic in soil by NCI workers arepredicted to be unacceptable in (i.e., lrarranting remedial action) in EU-3 and EU-4 onLy. The cancer and
non-cancer risks associated with the reasonable maximum exposure to arsenic in soil- by CI workers arepredicted to be r-rnaccept.able in all- elq)osure uni-t.s. The cancer and non-cancer risks associated with Ehe
reasona.ble maj<imum e>q)osure t.o arsenic by residents within t.he on-faciliEy area are unaccept.able in one
exposure unit, EU-8. As can be seen in Figure 2, EU-} i.s adjacent to areas where people are currentlyliving. However, no trailers are present and no people currently reside within this EU.
In the off-facility area, risks to residents are unacceptabl-e in ISz-8. Close inspection of ISz-B revealsthat the unacceptable risk is attributable to one property. The risk assessment broadly assumed that aIloff-faci]ity properties were used as residences. This part.icular property is used for a commercialbusiness (it is a lumber yard) and is e>q>ected to remain in commercial use in the fut.ure. Comparison ofsoil concentrations to chose considered to be acceptable for NCr workers demonstratses that risks are
acceptable for commercial" use of this property.
The risks associated Iritsh the reasonable maximum exposure to arsenic in ground water are summarized in
Tab1e 13 excerpted from the final Human Health Baseline Risk Assessment. As can be seen in the table, t.he
non-cancer and cancer risks associated with erq)osure to arsenic in ground water are unacceptable for both
workers and residents.
The risk assessment also evaluated the potential risks associat.ed with exlgosure of teenagers to slag
while visiting the Site. The cancer and non-cancer risks associated with the reasonable maximum e)q)osure
to arsenic in slag are below a 1evel of concern. The hazard quotient is 0.2 and the cancer risk is
1x10-5.
8 .l-.2 Lead Risks
The health risks associated with exposure to lead are evaluated in a different manner than those
associated with e>cposure to arsenic. The health effect of most concern associated with lead e>q>osure isthe impairment of the nervous system, especialLy in young children and unborn children. Analyses
conducted by the Centers for Disease Control and EPA associate 1eve1s of lead in the blood of t0
micrograms per deciliter (ug/dl,) and higher with health effects in children. EpA's risk management goal
for lead is to achieve a leweL of protectiveness such that a typical child or group of similarly exposed
chil-dren would have an estimated risk of no more than 5? of exceeding the 10 ug/dl, blood lead l-evel. Therisk assessment resul-ts for lead elqposure at the Site are reported as the probability of an individual
child or the fetus of an individual pregnant worker having a blood 1evel above the L0 ug/dl goa1. EpArs
Integrated Ercposure/Uptake Biokinetic Model was used to assess risks to residential children. A
biokinetic slope fact.or approach was used to assess risks to adults and teenagers. The risk assessment
considered t,he elq)osed population within the on-facility EUs t--7 to be adults.
The health risks associated with exposure to lead in soils at the site are summarized in Tab1es L4 and l-5
excerpted from the final Human Health Baseline Risk Assessment.. Risks Eo NCI workers are predicted to
exceed EPA's health goals in EU-3 onIy. However, Ehe heal-t.h risks associated with eq)osure to lead insoils by CI workers exceed EPA's health goals j-n all exposure units, wi.th probabilit.ies of 25*-99t of
exceeding the target blood lead leve1. The risks from e>rposure to lead within the on-facility residential
areas of EU 8, 9 and Ll- are predicted to exceed EPA's health goals. In the resj.dential areas south and
west of the site, risks from elq)osure to lead exceed EPA'S health goals in ISZ-1, ISZ-3, 13Z-6, I-SZ.7,
and ISZ-8. C1ose inspection of these results showed that. ISZ-3 was occupied by the Murray High School and
commercial businesses and further, the elevated lead levels in ISz-8 were associated with commercialproperties. Considering these land uses, the lead risks in ISz-3 and ISZ-8 were determined by EpA to be
acceptable. Supplemental sampling and refinement of the risk assessment was limited to rsz-1, rsz-G, and
The risk assessment also evaluated the potential effect of the e>.posure of teenagers to slag whj-1evisiting the Site. The assessment concluded that t.here i.s a less than 0.02? proba-bility of exceeding
EPA'S health based goal as a result of this e>q)osure.
8.2. Ecological Risks
The ecological risk assessment evaluated potential exposures of fish, birds, mallard ducks, frogs, andpocket gophers to smelter related chemicaLs of concern within like]y habitat areas. potential risks toecological receptors were estimated by calcutating Hazard Quotients (HQs) and Hazard Indices (HIs). The
HQ is the ratio of environmental concentrat.ion or dose to a safe level or dose. rf the He for a chemicalis egual to or less than 1, it is assumed that there is no appreciabLe risk that adverse hea]th effectswill- occur. If an HQ exceeds 1, there j-s some possibility that adverse effects may occur. although an He
above 1 does not indicate an effect wil-] definitely occur. However, the larger the He va]ue, the more
1ike1y it is that an adverse effect may occur.
Hazard quotients for each contamj.nant at each location and by each pathway were summed to obtaj.n a Hazardfndex (Hr) for each receptsor. Figures ).4 Eo L7 summarize tshe HIs for the belted kingfisher, ki1ldeer,
va1ley gopher, and the mal-l-ard. The assessmenL considered exposure via ingestion of wat.er, sedj-ment.,soil, and food within the ecolocical study area of the site. The HI,s are calculated for both the No
Observed Adverse Effect Level (NOAEL) and the Lowest Observed Adverse Effect Level (LOAEL). The NOAEL HIis appropriate to consider when determining risks to individual ecological, receptors. The LOAEL HI best
characterizes rj-sks to populations. Figr.rres for the kingfisher and mal-lard a1so illustrate an adjustmentwith "area use factors" as their home ranges are larger than the actual Site areas. A1J. figuresj.llustrate risk up gradient of the Site, on-Site, down gradient of the Site, and j-n the depressions(wetlands). Lead concent.rations in soils and sediments as well as selenium concent.rations in plants arethe largest contributors to risk to ecological receptors at the Site.
Hazard quotients for trout and frogs were calculated by comparing e>q)osure point concentrations for
surface vrater with toxicity reference values. The evaluation, documented in t.he ecological risk
assessment, shows essent.ially no risks to brown trout or frogs in Little Cottonwood Creek.
I - 2 - 1 Di scrrssi on of Rcqrrl t-q
The estimate of relative risk is the risk esLimate on-Site divided by the risk estimate up gradient. ftis a useful measure of how much higher the risk is due to the Site rel-atiwe to inherent risks. The
estimate of absolute risk is the HQ or the HI for each location. As can be seen in Figures 14-l-7. ingeneral, the relative risks to terrestrial receptors on-Site are two or more times higher than the risks
observed up gradient. Both relative risk estimates and absolute risk est.imates are considered by EpA whendetermining if remedial action is warranted. There are essentialJ-y no risks to aquatic life in L1tt1e
CoLtonwood Creek considering bot.h relative and absolute risk estimaLes. The greatest areas of concern atthe site are the wetlands, $rhere both absolute and relative ri-sk estimates are high.
Interpretation of these risk estimates must take into account the fo11owing sources of uncertainty in thecalculations:
I.where measured concentration data were not availabl-e, literature based bioaccumulatj-on factors wereapplied to estimate concentrations. This use of predicted rather than measured data adds to theuncertainty in the assessment. This uncertainty may be significant for the risks predicted for themallard and the pocket gopher, since predicted excess risk is associated with ingestion ofcontaminants in vegetation. These plant concentrations driving the risk were predicted usj-ngliterature based bioaccumulation factors. without crue site measurements, it is di-fficult to ascertaini-f this risk is representative.
Sample preparation may also Iead to some degree of r:ncertainty. Benthic macro invertebrates which were
connected at this Site $rere not rinsed prior to analysj-s. This could lead to a carry over of sedimentsthereby influencing contaminant levels in this media. Sediments were ground and acid-digested. This
method of treatment could possibly lead to a release of contaminants from the sediment which might not.typically be available to a receptor. Therefore, EPA believes preparation of samples collected fromthis site to support the ecological risk assessment may have contributed to artificially high met.a1concentrations, thereby elevating risk estimates.
3. The risks were cal-culated on the assumption t.hat
location. Depending on the home range and actual
lower.
the receptor spent l-00?; of its time within a
use of each location, the actual risks could be
observations of the ecological receptors at the Site in the form of qualitative surveys documented in theecological risk assessment. suggest that the predicted effects are not occurring. EpA believes thatfurther biomonitoring is needed to val-idate this assumption. Attempts to reduce the risks through activemeasures such as removing and replacing sediment.s in the wetlands will 1ike1y resul-t in ]oss of thehabitat. rn EPA's judgement. the wetl-ands are of great. ecologi-caI interest and loss of this habitat mayhave a more negaLive impact on the 1oca1 ecosystem than the highly uncertain predicted risks.
Also relevant to the discussion of ecological risks is the fact that current Site devel-opment plans
incl-ude extensiwe regrading which wil-I Iike1y result in filling of the wet.lands. The Corps of Engineershas jurisdiction over the u/etlands if affected by development actions and may or may not a11ow t.hefilling of these wetl-ands. If it were to occur, the filling of the wetlands would be an ecological impactin itse1f but would essentially break the exposure pathways of concern for ecological receptors.
8.3 Remedial Act,ion Objectives
The basel-ine risk assessment provides the basis for EPA's decision that actua] or threatened rel-eases ofhazardous substances at the Site may present an imminent and substantial endangerment to pubtic health,welfare, or the environment. Specifically, unacceptable risks were identified for the following exposedpopulations via the ingest.ion of arsenic and l-ead in dust. and soil and the ingestion of arseni.c in ground
water.
Current and Future NCI Workers
Current Cf Workers
Current and Future Residents
EPA has det.ermined that remediaL action is warranted at this Site. Remedial Action Objectives (RAOs) were
deveJ-oped by EPA for t.he elposure pathways and contaminants of concern associated with unacceptable risksunder the current and reasonably anticipated fut.ure land use. These RAOS are presented in this sect.ion.
8.3.1 Overarchi.nq RAO
Development of the on-facility portion of the SiEe is a key assumption on which this remedy decision is
based. Integration of development and Site remediation is a goal of EPA's Brownfields program. EPA's
Brownfields Initiative is an organized commit.ment to help communities revitatize properties where
e>q>ansion or redewelopment is complicaced by real or perceived environmental contamination, to mitigat.e
potenti.al health risks, and to restore economic vitality. Based on consideration of Brownfields goa1s,
the key overarching RAO is:
Develop a comprehensive remedy that protects human health and the environment, is
consistent with the current and reasonably anticipated future land use, and removes
obstacles to Site development associated with real or perceived environmental contamination,
EPA developed media-specific RAOS using the basic assumption that the reasonably ant.icipated future land
use will be commercial/light industrial use of the on-facility area and residential use of theoff-facility areas where homes are currently located. EPA based this assumption on the information
gathered during the Site Characterization and subsequent Murray Smelter Working Group sessions a1I of
which is summarized in Section 3.1. This information supports EPA'S conclusion that the currentindustrial and residential use of the on-facility property will end in the very near future.
8.3.2 Chemical Soecific Aopficable or Relevant and Appropriat.e Reouirements (ARi\Rs)
In accordance with the National Contingency Plan (NCP), remediation levels are a subset of the RAos andconsist of medium-specific chemical concentrations that are protective of human health and the
environment. These remediation levels are based on rj-sk assessment or ARARs. Table 15 presents the
chemical specific ARARs for the Site which are incorporated into the RAos as remediation levels to
address specific contaminants and e>q>osure pathways. Appendix B presents the derivation of the risk based
remediation Ievels for soil which are also incorporated into the RAOs. Appendix C presents the technical
support for EPA's selection of the remediation level for arsenic i-n shallow ground water.
8.3.3 On-FaciLitv Soil/Smelter l{aterials
RAOs: Prevent unacceptable risks to current and future workers or to ecologi-cal
receptors due to the ingestion of soil/smelter materials containing arsenic
or l-ead.
Reduce the uncertainties in the predicted risks to ecological receptors
Remediation Levels:
The remediation leve1s for soils/smelter materials are risk-based.
F'or workers, prevent e>q)osure to soils/smelter materials containing levels
of arsenic or lead which wourd pose a potenLial excess cancer risk greater
than 1E-4; a potential chronic hea]th risk defined by a hazard quotient of
one; or result in a greater than 5? chance that the fetus of a pregnant
worker would have a bl-ood Lead level greater than 10 micrograms per
deciliter (l1/dJ.l. Based or the findings of the Baseline Human Health
Risk Assessment and a reasonably anticipated future Land use that is
commercial/Iight industrial, these 1ewe1s correspond to:
Surface soils sha11 not exceed 1,200 milligrams per kilogram
(mg/kg) arsenj-c as the 95? upper confidence limit on the arithmetic
mean within any given erq>osure unit.
Surface soils sha1l not exceed 5,600 mg/kg lead as the arithmetic
mean withj-n any giwen eq)osure unit..
8.3.4 On-Facilitv Groundwater
Minimize future transport of arsenic from source materials t.o Ehe shallow aguifer.
Prevent exposure of human and ecological receptors to ground wat.er with
arsenic concentrations that represent an rmacceptable risk.
Prevent unacceptable increases in the arsenic concent.rations of the
intermediate aquifer resulting from arsenic migration from t.he shallow aquifer.
RAOs:
Remediation leveIs:
The remediation levels for ground waLer are based on ground water ARARs.
Meet the MCL (0.05 milligrams per Liter (mglr-)) for dissoLved arsenic in
shallow gror,rndwater at the east and west SiE.e boundaries.
MeeL the MCL (0.05 mg/L) for dissolved arsenic in the intermediate aguifer.
Meet the Alternate Concentrati-on Limit (ACL) of S.0 mg/L for dissolved
iil"lli;,H::",:H.ff::'il:"^:l"ii":,:ff*";,:il:T"::: :::",:"H:ariesvicinity of ground water discharge locations south of Littl-e Cottonsrood Creek.
8.3.5 Little Cottonwood Creek Surface warer
RAOs Protect Little cottonwood Creek water guality by preventing unacceptable
increases of arsenic concentrations in surface water resulting from ground
water discharges or surface !'/ater run-off from the Site.
Remediation Levels:
The remediation levels for surface water are based on surface water ARARs.
Meet the utah standards of euality for waters of the state for trivalent.
arsenic of l-90 micrograms per lj-ter (ug/r,) as a 4 day average and 360 ugr/Las a t hour average in Little Cottonwood Creek.
Meet the utah standard of euality for waters of the state for dissorved
arsenic of L00 ug/1, in IJittle Cottonwood Creek.
8.3.5 Off-Facility Soils
RAOs:Prevent unacceptable risks to current and future residents due to theingestion of soil contaj-ning 1ead.
Prevent unacceptabre risks to current and future NCr workers due to the
ingestJ.on of soil- containing lead.
Remediation Levels:
The remediation 1eve1s for off-facility soils are risk based.
The concentration of lead in surface soils within residential areas of the SiLeshalr not exceed 1200 mg/kg as an arithmetic mean within any givenresidential yard. EPA developed a range of 530 mg/kg-t2iO mg/kg for the
remediation leveI for soil-s in residential areas. Appendix B provides thedetails of the development of this range. The ApriJ_ 23, 199T risk
management strategry prepared by EpA provides the rationale for EpA,sselection of 1200 mg,/kg as the appropriate remediation revel for the
residential areas of this Site. The specific factors consi-dered in making thisdetermination for each property were the current land use, the reasonabryanticipated land use, the likelihood of exposure to soil- (measuredqua]itatively by ground cover), and empirical- evidence of e>q>osure to 1ead.
The concentration of lead in surface soils within commercial areas of thesite sha1l noE exceed 5600 mg/kg as an aritLmetic mean wi-thi-n any given
commercj-a1 property.
8.3.7 On-Facilitv Ecoloqical Studv Areas
RAO:Reduce uncertaint.ies in predicted risks to ecological receptors.
9,0 COITIPARATT\rE AIIAITYSIS
This sect.ion present,s, a summary of the comparative analysj-s of the remedial alternatives developed for
the Site to achieve t.he RAOs. This two-stage analysis rewiews the remedial- alternatives in relation to
the threshold criteria and primary balancing crit.eria specified in the National Contingency plan (NCp).
Modifying criteria are then discussed in Section 9.2. The findings of the comparative ana).ysis are
summarized i.n Section 9.3, including selection of a comprehensive remedy for the entire Site.
9.1 Identification of Alteraatives
A range of comprehensive remedial alternatives was developed to address human health risks and
environmental protection for the Site. For the purpose of organizing the various Sj.t.e materials and their
associated environmental effects, smelter materials present in the on-facility area of the Site were put
into one of four categories based on information from the Site Characcerization Report and tshe Baseline
Risk Assessment:
Category I and II: Category I and II materials are the sources of arsenic concentrations in
ground water above the ACL. Both relatively high arsenic concentrations
and large material volumes are necessary for material to be a potential
threat to ground water and be ctassified as Category r or II. Alternatj-ves
were developed for Category I and II ground water source material to
achieve the RAO of minimizing future transport of arsenic from source
materials to the shallow ground water. Alternatives for Category I and II
material must achieve the remediation levels esEablished for ground water.
Category T: Category I materials are distinct in that they are considered by EpA to be
principal threat wastes characterized as large volumes of material
containing relatively undiluted arsenic trioxide. There is an estimated
quantity of 2000 cubic yards of Category I material withj-n the on-facility
area. The identification of Category I materials considers:
A. Associated with distinctly elevated arsenj-c concentrations in underlying
shallow ground water (greater than or egual to 15 mg/L),
B. High arsenic concentrations compared to other categories of mat.erials on Site,.
C. Visual characterist.ics (e.9., color, particle size) whi-ch indicate arsenic
trioxide;
D. Direct contact risks which are considered to be a principal threat if this
material were ever brought to the surface at the Site,. and
E. Locat.ed where former smelter structures which processed or stored
arsenic trioxide were historicatly located. Category I mauerials are located
in the areas of tshe arsenic kitchens, the western compartment of the
baghouse, and the arsenic storage bin(s). The exact limits of Category I
material will be defined in remedial desj.grn considering the results of
sampling maEerial deeper or adjacent to this material.
Category II: Low 1eveI threat around water source material characterized as large volumes of
diluted arsenic trioxide or flue dust often mixed with soj.I, new fiI1, or debris from
former smelter fIues. These materials have lower arsenic concentrations than
Category I materials and are potentially a sigrnificant source of ground water
contamination. There is an estimated guantity of 68,000 cubic yards of Category,
II material within the on-facility area. The identification of Category II materials
considers:
A. Located near or witshin the footprint of former smelter structures such
as the concrete flues, the roasting p1ant, the baghouse, storage areas,
transport areas, and the blast furnace area. The exact l_imits of Category II
material will be defined in remediaL design considering the results of
sampling material deeper or adjacent to this material;
B. VisuaL characteristics (e.9., coIor, particle size) which indicate flue dust
or diluted arsenic trioxide; and
C. Pot.ential current or future threat to ground water quality. Category II
material is associated with arsenic in shallow ground water above the ACL.
Category IfI: Category ffI mat.erj.als are surface soiLs which are predicted to pose an
unacceptable risk to NCI workers within the on-facility area. Alternatives for
Category III material-s must achieve the remediation 1eve1s for on-facility,
soils/smelter material-s. Material in thi-s category will not pose a threat to ground
water. The identification of Category fII materials considers;
A. Located srithin on-facj-lity EUs identified as causj-ng rmacceptable heal-th
risks to NCI workers (EU-3 and EU-4).
B. Lead concent.ratj.ons greater than sGOO mg/kg as the arithmetic mean
within the EU; and
C. Arsenic concentrations greater than l-2OO mg/kg as the 95? upper
confidence limit on the arithmetic mean within the EU.
Category IV: Slag
Remedial alternatives were developed to address all four categories of smelter mat.erials. The key
components of each al-ternative considered in the comparative analysis are summarized be1ow.
Alternative l- - No Action
' The Murray Smelter Site would be left in its current condition.
Alternative 2 - Excavation & onsite Consolidation/Barri-er pl-acement/Monitored NaturalAttenuation/Institutional Controls Removal and Disoosal of Off-Facilitv Soifs
t source control via excavation of Category I and II materials and consolidation in separate
.repositories in the on-facility area.
t Monitored natural attenuation of shall-ow ground water within and down gradient of source
areas to achieve the ACL. The mechanism of attenuation of arsenic in shatlow ground water is
adsorption to the j_ron oxides in the subsurface soi1.
' Surface water monitoring j-n Little Cottonwood Creek and monitoring of the on-site ecological
study area. Monitoring of wetlands wil-I include surface water, sediment and benthic macroinvertebrates. Monitoring of terrestrial- areas will include plants and soi1.
o Institutional- controls in the form of a Murray City ordinance establishing an "overlaydistrict" which includes zoning to prevent residential and contact i-ntensive industrial useswithin the former smelter operationa1 areas, prohibitions on the development or use of any
ground water wel-Is within Site boundaries for EPA approved monitoring we1ls, maintenance ofthe barriers, and controls on excavated subsurface material wj-thin the former smelt.eroperational areas. Other institutional controls include restrictive easements that run withthe l-and which contain the same land use and ground water well construction restrictions.
t Covering of Cat,egory III materials in place with barriers sufficient to prevent direct
contact. Such barriers may be pavement. landscaping, soil caps, or sidewalks.
' soil removal/repl-acement with clean soil, or other fill in off-facility residential or
commercial properties with lead concentrations in soils that may represent an unacceptablerisk- Excavated soil will be used in the on-facili-ty area of the Site as subgrade material
during devel_opment or road construction.
Afternative 3 - Excavation/onsite Consolidation& offsite Disoosal-/Monitored NaturalAttenuation/Barrier Placement/InsLitutional Controls/Removal and Disposaf of Off-Facifitv Soils
' The same actions as Alternat.ive 2, except Category I materials are excavated and disposed
offsite.
Afternative 4 - Excavation/onsite Consolidation& offsite Disposal/Barrier pl-acement/Institutionaf
Controls/Ground Water Extraction/Remowa'l and Itisnosa'l of off-E:ciIirrr qnirc
o A11 Alternative 3 component.s.
Ground r^rater extraction in areas of ri-chest arsenic concentrations, treat,ment of extracted
ground $rater, and discharge to the sanitary sevrer system.
Alternative 5 - Excavation/Onsite Consolidat.ion& Offsite Disposal-/Barrier placement/InsEitutional
Controfs/In-Situ Ground Water Treatment/Removal and Disposal of Off-Facilitv soils
AI1 Alternative 3 components.
option A - Constructed wetlands to treat shal1ow ground water pri.or to discharge to Little
Cot.tonwood Creek.
Option B - Permeabl-e barrier treatment hrall to treat shallow gror.rnd water prior to
discharge to Little Cottonwood Creek.
Alternative 5 - Excavation/Onsite ConsolidaLion & Off Site Disposal/Monitored Natural Attenuation/BarrierPfacement/Institutlonal Controls/Off-Facilitw Commr:nitv Health Education. Monitorinq and Inten,ention
o A11 Alternat.ive 3 components for the on-facility area.
Community health education and monitoring for resj-dents and workers in off-facility areas of
concern. This alternative also includes intervention actions such as surface control,barrier placement or soil removal, if the potential for unacceptable ri-sk is indicated by
uhe monitoring program.
After-native 7 - Excavat.ion/onsite consolidation & offsi-te Disposal/Monitored Natural
Attenuation/Barrier Placement/InsEitutional controls/soi1 Tillinq in off-facilitv Areas
AI1 Alt.ernative 3 components for t.he on-facility area
Deep tilIi.ng in off-facility residentiaL or commercial properties with lead concentrati-onsin soils that may represent an unacceptabte risk. Institutional controls to protect, theintegrity of soil barriers and to place reguirements on the handling and disposal of any
excavated material from beneath the tilled zone if the concentrations i.n t.his material are
above a level of concern.
9.1.1 Threshold Criteria Analvsis
9 .1. 1.1 Overall Protection of Human Health and the Environment
As demonstrated in the Baseline Risk Assessment, Alternative t, No Action does not meet the thresholdcriteria of overall protection of human health and the environment except that no action is appropriatefor slag since no unacceptable risks associated with e>q>osure to slag were identified by EpA in EheBaseline Risk Assessment. Wj-th the exception of Alternative L, al1 alternatives considered in the
comparative analysis meet the requirements of the RAos and provide overall protection of human health andthe environment. Differences in overall protection are related to the 1evel of certainty with regard toactions for category I materials and relative effectiveness of actions on ground water and theoff-facil-ity soi1s. There are also differences with respect to the key overarching RAo requiring thatremedial actions be consistenc with the current and proposed land use.
Source control via excavation and consolidation of Category I and II materials in separate repositories(Alterative 2) would prevent future infiltration of surface water, thus protecting ground water fromfurther impact due to transport of arsenic from this source material. Excavatj-on/onsite consolidation isan effective method of source control at this Site primarily due to the ease in locating ghe sourcematerial. The material is generally r^rithin the tocations of historical smelter structures. For example,the results of sampling subsurface soils to a depth of 5 feet in the vicinity of the baghouse show thatexcavation of the upper 2 feet of material from within the footprint of the former baghouse would removeapproximately 97 percent of the arsenic present. in t.hi-s source area. (This calculatsion was done bydividing the mass of arsenic in 2 feeE by the tsotal mass of arsenic measured in 5 feet of subsurface soilat the Location of the highest arsenic level_s.)
Barrier placement over Category IIr materials is a component of all alternatives except Alternative I and
wouLd be effective in preventing di.rect elq)osure as long as barriers are maintained. The institutionalcontroLs which include public and private land use restrictions and a ban on construction of ground wat.erwel-ls (with the exception of EPA approved monitoring weLfs) within the on-facility area will prevenE. Site
uses which could result i.n unacceptable risks due to residentj.al or contact intensive use or gro,nd wat.eringestion. rn the off-facility area, soils containing lead exceeding remediat,ion leveLs would be
excavated t.o at least 18 inches and t.he excavated soJ-I brought onto the on-facitity area for
incorporation into remedj-a1 acLions or development- The off-facility excavated areas would be replaced
with soil or other clean fi1l. Removal of soil with l-ead concentrations above remediation 1eve1s provides
protection of human health and the environment by breaking the e>rposure pathway of direct contact with
contaminat.ed source mat.eriaf .
The source control action for Category I materials in Alternatives 3, 4, and 5 is off-site disposal-.
Although both on-site disposal (Alternative 2) and off-site disposal (Alternatives 3, 4, and 5) actionsprovide essentially the same 1eve1 of overall protection, removal of Category f materials from the Sj-te
would eliminate completely any long-term concerns regarding the potential for direct elq)osure (the 1eve1sof arsenic in Category I materials may cause acute health effects) and the potential for the mat.erials toact as sources of arsenic to ground water in the future (arsenic in Category I materials is pr'edominantly
the soluble oxide and sulfate forms) in the event that the repository was damaged resulting in a releaseof these maEerials into the envj.ronment. Although not likely to occur, the possibility of igs occurrenceillustrates the difference between the two alternatives.
Alternati.ve 4 contains the same components as Alternative 3 and adds a ground water extraction system.Site specific hydrologic and chemical factors limit arsenic transport rates to the extraction wel1s andthus limit the rate at which arsenic may be removed from the aquifer. Long term pumping rates are timited
by the flux or supply of grollnd wat.er introduced to the aguifer. section 4 of Appendix A of theFeasibility st.udy contains a conceptual design for a ground water extraction system and approximate time
frames are predi.cted for arsenic ext.raction rates. The analysis demonstrates that the f\:x of water
through targeted portions of the aquifer will not change as a result of instal-Iing a pumping system.Therefore, addition of an extraction system within the source areas will not accelerate t.he rates ofdecline in arsenic concentrations in ground water relative to the rates achieved t.hrough source control
and natural attenuation. The time frame reguired to meet remediation level-s in ground water $rithin the
source areas is predicted to be between 1Oo-125 years with the installation of a ground water extraction
system. Monitored natural attenuation is predicted to reguire approximately 1OO-150 years to achieve
remediation levels throughout the Site. For both source control with moniEored natural attenuation andsource control with ground water extraction, the same set of sit.e specific factors limits the rate atwhich arsenic concentrations will decline. In addition, operation of an extraction system may not be
compatible with the desired future land use, because of the large area and numerous weI1s necessary.
Al-ternative 5 contains the same components of Alternative 3 and adds in-situ treatment of shallow groundwater (either by constructed wetLands or by a permeable barrj-er treatment wa1l) near Little cottonwood
Creek. Currently ground water discharges to Little Cottonwood Creek. However, the principal areas ofelevated arsenic concentrations in gror-rnd water are distant from t.he creek and are not predj-cted tointercept the creek for over l-00 years. Due to source control and attenuation within the aquifer, arsenicconcentrations are elq)ected to be significantly lower by the time arsenic from these areas intercepts thecreek' The types of treatment systems included in Alternatj.ve 5 are not elq)ected to be effective forperiods greater than 10 years without extensive routine maintenance. Implementation of either treatmentoption will have limited short-term effect.iveness due to Ehe diffuse source areas which may j-nclude
ground water from both sides of the creek and surface water runoff and complex ground rdater fLow pat.ternsnear the creek and may provide no benefit for long-term effectiveness in reducing arsenic transport toLittle Cottonwood Creek. Therefore, implementation of in-situ gror.rnd water treatment systems j-s not
elq)ected to provide additional performance over t.he source controL and monitoring actions included inAlternative 3.
Al-ternatives 5 and 7 include two different options for addressing the off-facility soils containing
Llnacceptable concentraEions of 1ead. Alternative 6 includes community education to inform residents on
methods t.o prevent unaccepcable e)cposures and a voluntary blood-lead monj.tori-ng program. rf the
monitoring program indicates the potential for unacceptable risk intervention actj.ons would be
impl-emented. These actions would be designed on a case-by-case basis and couid include surface control-such as vegetation of bare areas, barrier placement or soil removals. This alternative is ercpected to beprotective of human heal-th if participation in the program is sufficj-ently high. Alternative 7, soiltilling, is also elq)ected to be protective of human heaLth and the environment. rn the majority ofoff-facility areas of concern, lead concentrations are elevated at the surface. The source of this leadis like1y due tso deposit.ion of emissions from Ehe smelEer during it.s period of operation. In Ehese cases,
deep tilling will reduce lead concentrations to below levels of concern. Site characterization dataindicate that at some locations lead concent.rat.ions are above a Level of concern over the entire tillingzone, possibly due to the placement of s1ag. In these areas, l-ead concentrations in surface solls woufdnot be reduced below a level of concern by tilling and community health education and monitoring would be
implemented to provide long term protection.
9.1.2 Compliance with Aoolj.cable or Relevant and Appropriate Recruirements
9.1.2.1 Ground Water ARARS
Chemical specific ARARs are identified in Table 16. Section 121(d)(2)(B)(ii) of the Comprehensive
Environmental Response Compensation and Liability Act (CERCLA) allows EpA to establish alternate
concentration limits (ACLs) to t.hose otherwise applicable under the following conditions staced in 55
Federal Register 8732:
The ground water must have a known or projected point of entry to surface wat.er wit.h no
statistical-ly sigrrificant increase in contaminant, concentration in t.he surface water from
grorlnd vrater at the point of entry, or at any point where there is reason to believe
accumulation of constituents may occur dohrnstream. In addition, the remedi-al action
must include enforceabl-e measures that witl preclude human exposure to the contaminated
ground water at any point betsreen the facility boundary and all known and projected
points of entry of such ground water into surface $/ater.
Quarterly monitoring of surface water and ground water at the Site has demonstrated that ground water
from the shallow aquifer discharges to Little Cott.onwood Creek at locations along the northern Site
boundary. The contaminant of concern in ground water is arsenic. Information collected since Apri1, 1997
and documented in quarterly monitoring reports indicates the prj-mary source of arsenic to Little
Cottonwood Creek exists at a point discharge at the east,ern facility boundary. Loading calculations
i.ndicate that 88?-l-00? of the arsenic loading to Little Cottonwood Creek is due to this point discharge,not t.o the ground water discharge from the Site. EPA has deLermined that the conditions at Murray Smelter
satj-sfy the requirements of CERCLA ),22(d) (2) (B) (ii) which a1l-ow the establishment of an ACL for
groundwater. EPA has established 5.0 mg/L as tshe ACL for dissolved arsenic in ground water. Appendix Cprovides a summary of the calculations used by EPA to determine a rErnge of acceptable ACLs. rn making its
determinatsion, EPA considered the zone of potential shallow gror:nd water discharge from the Site and
conservatively assumed all discharge is from the Site or south side of Ehe creek. EpA also based its
determination on low flow conditions in Little Cot.tonwood Creek and Site specific hydraulic conductivity
and hydraulic aradient measurements. The ACL of 5.0 mg/L for dissotved arsenic is a ground water
concent.ration which will assure that Little Cottonwood Creek is protected at iLs beneficial use,agricultural use, given the discharge of shallow grorlnd water to the creek.
rn accordance with the NCP, the situation at Murray Smelter fulfi1ls the CERCLA statutory criteria for
ACLs, J.ncluding the analysis in the Feasibility Study which demonstrates that active restoratj-on of the
groundwater to MCLs is not practicable. The existing documentation of these conditions precludes the needfor an ARAR waiver. The remediation level for dissolved arsenic in shallow ground watser within the site
boundaries is the ACL of 5.0 mg/L. Achieving this Ievel will constitute compliance with the groundwater
ARARs. The MCL is currently met at the on-facility area boundarj.es (the north boundary is north of the
ground water-surface $rater mixing zone norlh of Little cottonwood creek).
Source control actions contained in Alternatives 2 through 5 are expected to minimize transport ofarsenic from smel-ter materials and result in improvement of ground water quality such that the ACL will
be met wilhin the entire on-facility area in a time frame of 1OO-l-50 years. This approach is reasonablegiven the unlikelihood that the shallow aquifer will ever be in demand as a drinking water source.
Improvement in ground water quality would also reduce arsenic discharge to the creek. The additionalaction of ground water extraction contained in Al-ternative 4 r,rould not result in a significant decreasein the time required to meet the ACL or a reduction in arsenic loading to the creek. Time frames forachieving the ACL in Alternative 4 are estimated to be 1OO-125 years. There are fundamental technical-limitations for the effective performance of an extraction system rel-ated to the 1ow aquifer yield andhigh partitioning of arsenic to aquifer solids. The additional actsion of an in-situ treatment containedin Alternative 5 would not contribute to reduction of current arsenic concentrations in the shallowaquifer and would have a minimal effect on near- and long-term loading of arsenic to Little Cottonwood
Creek. The areas of highest arsenic concentration are currently distant from the creek and are notpredicted to intercept the creek for at least 100 years. Attenuation by adsorption is erq>ected tosignificantly reduee t.he arsenic concentraEions from t.hese areas by tshe time E.hey reach the creek.
The ACL is currently achieved at monitoring well Mw-112, the well locat.ion closest to compliance points
near Litt.le cottonwood Creek which will be established as part of the remedy. within 30-40 years, theeffects of Ehe source control act.ions of Alternative 3 along with the monitoring activities are expectedto demonstrate that the rate of natural attenuation of arsenic in shallow ground water i.s sufficient topredict that the ACL will never be exceeded at the established compliance points. EpA e)q)ects tshe
remaining areas of the shallow aguifer to achieve the ACL withj-n a time f:rame of 1oo-L50 years.
A)-though not ident.ified as a contaminant of concern, selenium has been detect.ed in the shallow ground
!,raEer $rithin tshe Site boundaries at leveIs exceeding the MCL of 0.05 mg/1,. These detections are at g weII
locat,ions within the on-facility area. However, the MCL for selenium has consistently been met at well
Locations just south of Litt1e Cottonwood Creek and the east, and west on-facility bor:ndaries (we1L
locations Mw-112, MW-109, Mw-102, and Mw- 104 on Figure 5). The preamble to the NCP states at 55 Federal
RegisEer 8753 :
"...there may be certain circumstances where a plume of ground water contamination is
caused by releases from several distinct sources Lhat are in close geographical proximity. "
In cases such as these, the NCP preamble suggests that.
'r.. 'the most feasible and effectj-ve ground water clean up strategy may be to address the
problem as a whole, rather than source by source, and to draw the point of compliance to
encompass the sources of release.'l
EPA considered this discussion, the proximity of the sources of arsenic and selenium (both within t,he
former smelter operational area), as well as the reliability of the restrictions on ground water use$rithin the Site boundaries in establishing the points of compliance for t.he selenium MCL at the well
locations just south of Little Cottonwood Creek. The ground water ARAR for selenium is currently met atthe points of compliance. Selenium witl be included as part of the ground water monitoring component ofthe remedy.
9.L.2.2 Surface Water AFtARs
State of Utah Water Quality Standards are identified as applicable in Tab1e 15. The data gathered duringthe site characterization effort and subsequent sampling'events indicate that Utah,s aquatic life
standard for arsenic (0.19 mg/L arsenic as As [IfI]) is consistently being met, but that the arsenic
standard for agricultural use (dissolved arsenic of 0.1 m /L) is not being met during low-f1ow conditionswithin the on-facility boundaries. The standards for both uses were met at. location SW-6, in Little
Cottonwood Creek downstream of the Site during the site characterization sampling events.
The source control actions wil-l address the Murray smelter-rel-ated source of the arsenic in the point
discharge from the culvert along State street which discharges to Little Cottonwood Creek. This source
has been located near the storm drain along State Street near the Doc and De11's trailer court. Thecontrol of t.his discharge and the natural at.tenuation of shallow ground water to the 1eve1 of the ACL is
elq)ected to result in compliance with the surface water ARARS in Little Cottonwood Creek within a period
of 3 years. The improvement of ground water quality as a result of source control, natural attenuation
and surface water management wi.Il proEect Little Cottonvrood Creek in the future.
Little Cottonwood Creek does not currently meet the beneficial use for agriculture due to high 1evels of
mS from urban runoff and high phosphorus. Neither TDS nor phosphorus are related to the Site. Aninvestigation of the actual use of Little Cottonwood Creek was conducted in Apri1, 1997. T$ro dj-versionsof surface water were observed up gradi-ent of the Site, neither of which was for agricultural use
purposes. No diversions were observed down gradient of the Site. This information suggests that thecurrent uses of Littl-e Cottonwood Creek are not consistent with the beneficial use. EpA believes that a 3year period for achieving the agricultural use standard for dissolved arsenic in Little Cott.onwood Creekis reasonable in this case.
9.1.2.3 Action- and Location- Specific ARARs
Tables L7 and 18 present the action specific and location specific ARARs for the Site. A11 alternatives
will meet these ARARs. On-facility alternatives which include consolidation of source materials within
the site boundaries do not tri-gger the land disposat restrictions, therefore these requirements are notapplicable. The Site boundaries are considered by EPA to be an ,,Area of Contamination" as defined in the
NCP. Movement of waste wj-thin an Area of Contamination does not constitut.e placement.
9.1.3 Primarv Balanci-nq Criteria
9.l-.3.1 Short.-Term Effecti.veness
As discussed above, alL alternatives with the exception of Alternat.j-ve 1, No Action, meet the
requirement.s of the RAos and prowide overall protection of human heaLth and the environment. There are nosubstantial differences between alternatives 2,3,4,and 5 in terms of short-term effectiveness. Eachalternative entails excavation and handling of Category r and Ir materials. However, dust control
measures are easy to implement and the potential for risks to the community or workers wilL be minimized.
Short-term risks from t.he presence of heavy construction equipment on the Site would be similar with
respecE tso each alternative as well as to the potentsial risks posed by current industrial uses. Responseobjectives would be met at the same time for all alternatives once excavated materials are disposed and
barriers installed.
Alternative 5 contains community health educati-on and monitoring for t.he off-facility area. Thisalternative provides a high leve1 of short term effectiveness. Al-though there are potential- uncertainties
associaLed with t.he willingness of residents to participate, the high 1eveI of involvemenE by Murray City
and the high level of community awareness concerning the site suggest that the program will be effectivein the short term. Alternative 7, tilling in the off-facility areas, may not be as effective as soil
removal in breaking the e:q>osure pathway due to the presence of lead below the tilling zone.
9 .t.3 .2 Long-term Effectiveness and permanence
A primary considerat.ion in the evaluatj-on of long-term effectiveness is that a major portion of theon-facility area is e>rpected to be redeveloped in the near future. The expected land use of office/Iight.
commercial wilf reduce the potenti-al for unacceptable risks of (',contact intensive" activities woul_dend), and integration of remedial actions wit.h redevelopment, the key overarching RAo, would allow foroptimizing the management of smelter materials remaining at the Site such that confi-dence woul-d beincreased that the remedy and subsequent institutional control/monitoring will be effective over the long
term.
Alternatives 2 and 3 di-ffer in terms of actions on Category r materi.als. Under Alternative 2, Category Imaterials would be excavated and consolidated in a repository in t.he on-facility area. Under Alternative3, category r materials would be excavated and disposed of off-site. Gj-ven the current and reasonablyanticipated future land use and the opportunity t.o install a repository in a suitable location under thecontrol of Murray City, both actions would provide long-term protection of human health and theenvironment: Removal of category r materials from the Site woul-d completely eliminate any future concerns
regarding the potential for direct e>q)osure or contact of Category I materials with infiltrating groundwater and therefore provide a higher level of performance in terms of long-term effectiveness. For
Category II materials, consolidation into a repository would provj.de long term protection of human health
and t.he environment. Category If materials may be low-level sources of arsenic to ground lrater underambient infil-tration conditions. Minimizing the potential for infiltration of surface water through thesemateriaLs by consolidation beneath a losr-permeability barrier with surface control is expected to beeffective in preventing migration of arsenic to ground water. This same action is included inAlternatives 2, 3, 4 and 5. control on the use of l-and and ground water, the second component of theinstitutional controls, will be effective in preventing direct contact with unacceptably high leve1s ofarsenic and lead in soil and ground water and will prevent the migration of arseni-c from the shallowaquifer to the i-ntermediate aquifer. These controls will be implemenEed through city zoning andrestrictive easements which run with the 1and. Thus they will be effectj-ve in the long term and are
considered permanent restrj-ctions .
Alternatives 3, 4 and 5 contain the same actj-ons on smelter materials and provide the same basic level oflong-term effectiveness. Alternatives 4 and 5 include additional actions to contain the extent of arsenictransport. Alternative 4 contains a ground $rater extraction system in the areas of highest arsenicconcentrations in the shallow ground water. The additional act.ion of ground water extraction would
eventual-Iy provide for reductions in arsenic concentrations in shallow ground rrater and would beeffective for long-term containment of arsenj-c already present in the shallow aquifer near the former
baghouse and thaw house areas. However, modeling indicates that an ext.ensive ground water extraction
system would not substantially reduce the time required to achieve the RAos for the shallow aguifer andLittle Cottonwood Creek. overall, Alternative 4 provides lower performance than Alternative 3 withrespect to long-term effectiveness because it would not provide a significant improvement j.n
environmental conditions relative to Alternative 3 and would entail a high level of operation and
maintenance.
Alternative 5 incl-udes in-situ treatment of shallow ground wacer in the vicinicy of Little Cottonwood
Creek with the purpose of limiting arsenic transport and discharge to the creek. Groundwater monit.oringindicates that the two principal areas of ground srater contamination do not currently extend to Little
cottonwood creek and are not. predicted to do so for more than 1oo years. Source control actions andnatural attenuation of arsenic in Ehe aguifer are e>q)ected to significantly reduce the arsenicconcentration by this time. The long-term performance of systems such as constructed wetlands andpermeable barrier treatment wal1s to treat arsenic is limj-ted. Effective removal is only elpected for aperiod of approximately Lo years due t.o che mi1d1y-oxidizing groundwater chemistry. Therefore, if theset)t)es of syst.ems were installed in the near future, they would not be effective at the time when arsenicfrom the principal source areas reaches them.
In the off-facility area, lead concentrat.ions in residentsial soils range up to 1,BOO mg/Kg. The
remediation 1eve1 lead in soj-1 in tshe off-facility area is 1,200 ppm. Alternative G. which includes
communiEy educat.ion to provj-de information on methods to prevent unacceptable e{posure, is e>q>ected toprovide long-term protection of human health through the education/monj-toring components with additional
assurErnce due to the option for inuervention measures in the future if the potential for unacceptable
exposures j-s indicated.
For Alternative 7, because l-ead concentrations are above leveLs of concern throughout the tilling layer
at some locations, tilling may not. always be effective in reducing concentrations to below the leve1 of
concern. In this case, Alternative 7 would rely on similar commr-rnity education measures described underAlternative 6. Therefore, Alternatives 5 and 7 essentially provide the same level of long-term
effectiveness.
The off-facility component of Alternatives 2,3,4, and 5 would provide a high }evel of long-term
protecEion because surface soils with lead concentrat.ions above a level of concern would be excavated and
replaced htith clean soil or other fill. ff complete removals are achieved, this action would prowide the
highest level of long-term effectiveness because all soil-s of concern would be removed.
9.1 .3 .3 Reduction of Toxicj-ty, Mobility and
With the exception of the no action alternative,
significantly different performances j-n terms of
lead through t.reatment.
Volume Through Treatment
the alternatives considered by EpA do not provide
reduction of toxj-city, mobj-Ij-ty and volume of arsenic or
Alternatives 2 and 3 do not contain any treatment components except the possible treatment of Category
material before disposal at an off-site facility. For Alternative 2, a reduction in the mobility of
arsenic in su.bsurface soils would be elq)ecued due to the minimization of infiltratj-on through Category
and II material-s. For Alternatives 3, 4 and 5 a simil-ar reduction would be expected due to removal of
Category I materials and minimization of infiltration through Category II materials.
Alternative 4 contains a treatment component; treatment of extracted ground rdater to remove arsenic prior
to discharge to the sartitary sewer. This treatment component would provide litt1e if any reduction in
toxicity, mobility or volume of arsenic at the Sj-te in comparison to ALternatives 2 and 3. However, the
ground water extraction system would provide some addit,ional reduction in mobilit.y of arsenic in t.he
shallow aquifer relative to Alt.ernatives 2 and 3 due to physi-cal containmenE of arsenic related to
sources in the former thaw house and baghouse areas. The aquifer characteristics which result in low-flow
rates and high arsenic attenuation currently limit the mobility of arsenic and an extraction system would
have minimal additional benefit.
The in-situ treatment of shallow ground water in the vicinity of Little Cottonwood Creek contained in
Alternative 5 would not provj-de any reduct.ion in toxicity or volume of arsenic at Ehe Site. rt would
provide a minor reduction in the mobility of arsenic in shaLlow ground water near Little Cottonvrood
Creek. As discussed above, the princj-paI areas of ground water contamination are distant from the creek
and arsenic from these areas is not predicted to intercept the creek for over LOO years. At this time,
the arsenic concentrations are predicted to be significantly lower due to the high attenuation of arsenic
in the aquifer. Passive constructed wetlands or a treatment wall would be elq)ected to operate efficientlyfor only 10 years without continued routine maintenance and wou1d, therefore, not be effective for the
time frame of principal interest.
overall, therefore there are no substantial differences in performance of t.he alternatives against thiscriterion. Alternatives 2, 3 and 5 perform at essentially the same 1eveI, whereas Alternative 4 performs
at a slightly higher 1evel due to physical containment of arsenic in shallow ground water.
For the off-facility area, lead is j.mmobile in Site soils and lead concentrations in the off-facility
area are weII below leve1s which would r^rarrant treatment. Treatment is therefore not applicable to
off-facility soi1s.
9.1.3.4 Implementability
The source control- act.ivities contsained in Alternatives 2, 3, 4 and 5 are implementable either forcurrent land use or for the e)q)ect,ed futsure land use. Excavat.ion of Category I and fI material-s would be
implementable with some minor disruptions to current industrial activities. physically suit,able
repository locations for Category I and If materials are also available for current or future land use.Off-site disposal of Category I materials (a component of Alternat.ives 3, 4 and 5) would also be readily
implementable. In addj.tion, barrier placement over Category IIf materials would be implementsable hrith
minor disruption to current industrial/commercial activj-ties, or could be implement.ed during
redevelopment of the area. Institutional controls to prot.ect barriers are implementable given the high
degree of involwement of the current land owners and Murray City.
Alternatives 4 and 5 cont.ain the same source control actions as Alternative 3 with the addition of twotlpes of remedial action alternatives on gror:nd $rater. The extract.ion system cont.ained in Alternative 4
would be difficult to implement due to the low yield of the aquifer and high partitioning of arsenic tothe aguifer solids. A large number of weLLs would be necessary, each pumping at a low rate over an
extended period of time. Operation and maintenance of this type of system, includi.ng a treatment planu
would be difficult and would not be compatible $rith future land use. Alternative 4 therefore has a lower
performance than Alternatives 2 and 3 in terms of implementability. Either of the options evaluated forin-situ ground water treatment under Alternative 5 (wetlands or treatment wa11) would have numeroustectrrical diffj.culties associated with effective implementation and operation. Consj-derations include theIimited area available (for wetlands), depth and complex flow patterns of ground water in the vicinity ofthe creek, the presence of the units j.n the flood pIain, and uncertainties associated lrit,h theeffectiveness of the technologies in removing arsenic. In addition, the technologies would reguire a highl-evel of long-term maintenance. For the ground water conditions forlnd at the site, effective performanceof the t)Pes of technologies under consideration is approximately Lo years without on-going maintenance,
Replacement of substrate in a wetlands or of ferric sulfate in a treatment waII may be required atapproximately lo-year intervals. This action would not be compatible wj-th the future land use andAlternative 5 has a lower performance than Alternative 3 in terms of implementability.
rn the off-facj-1ity area, community health education and monitoring programs contained in Alternative 5
would be readily implemented because only non-engineering controls are considered. Excavation and soilreplacement evaluated under Alternatives 2-5 are also e>cpected to be readily implemented. Residents inthe areas of concern have partj-cipated in the site characterization study, and there is a high level of
awareness concerning the site in the general community. These t]4)es of actions have been performed atseveral sites around the cor:ntry. Alternative 7, which requires soil tilling rather t.han excavation atthe same locations, would be more difficult to implement than the other alternatives. This is primarily
due to tectrrical difficulties of tilling in small spaces such as residential yards, where structures andplants would make some areas difficult to access.
9.1.3.s Cost Analysis
Details of the cost analysis are contai-ned in the final Feasibility Study. The costs estimated for Eheon-facility area are shown j-n Table 19.
Tab1e 19
Est.imated Costs - On-Facility Area (Ui1lious)
Alternative Alternative
23
Alternative Alternative
45a
$10.5
$0.21
$r.3 .4
Alternative
sb
i2L.9
$0 .23
s40.2
Item
Capital Cost
Annual O&M
Present Net
Worth
$8 .7
$0.14
$10.1
98.e
$0.14
$10 .3
$10.8
$0.27
$14 .3
o&M costs are estimated for 30 years. The extraction component of AlternaEive 4 and in Situ treatment
components of Alternative 5 would require O&M for over 100 years and so would entail substantially highercosts than shown above.
The cost to implement Alt.ernatives 2 and 3 is considered to be low; the costs to implement Alternative 4
and 5a are considered to be moderate; and the cost to implement alternative 5b is considered to be high.
The costs estimated for off-facility alternatives are shown in Tabte 20.
Table 20
Sumlary of Estimated Cost.s for Off-Facility Remedial Altsematives (Millioas)
AlternaEive
A
Alternat.ive ALternative
Item
Capital Cost
Annual O&M
Present Net
I^lorth
$0.s7
$0 .0s
$r- .34
7
$0 .64
$0.01s
$0. e3
2-5
$1.1
$0 .013
$1.33
9.2 Modifvinq Criteria
9 .2 .1 State Acceptsance
The Ut.ah Department of Environmental- Quality (UDEQ) was provided the opportr:nity t.o review and comment on
all documents generated in support of this remedial action decision. UDEQ also participated in all
meetings of the Murray Smelter Working Group and the technical task group meeLings. In conments on the
Proposed Plan. LIDEQ indicates agreement that Alt.ernative 3 is the most reasonable choice for t.he Site.
However, UDEQ indicated that this agreement was not based on the length of time or the current levels of
cont.amination. Given the 'textremely long" time frames and uncertainty j-nvolved in ground water
restoration under any alternative, UDEQ has determined that j,t is technically impracticable within a
reasonable t.ime frame to meet ARARs at this Site, and has agreed on that basis and for other reasons
given j-n this ROD (e.9., protection of human health and the environment) that the remedy described in
t.his RoD is appropriate. while EPA characterizes the situat.ion differentl-y, both parties are in agreement
alf,out t.he ultimat.e approach. UDEQ believes that the long time frame for achievj-ng ground water
remediation levels is acceptable only in the contexu of the t.echnical impract.icability
of any alternatives.
EPArs responses to UDEQ'S comments an the Proposed Plan are provided in the Responsiveness Summary of
t.his ROD.
9.2.2 Community Acceptance
Few comments were received from tshe community on the Proposed P1an. Based on these comments and EpA's
extensive work wlth the community through the Murray Smelter Working Group sessions, it appears that the
community accepts EPA's selected remedy presented in Section 9.4. EPA's responses t.o verbal and $rritten
comments on the proposed plan are provided in the Responsiveness Summary of the ROD.
9.3 SI'MMARY
Seven remedial- alternatives were evaluated for the Murray Smelter Site. Through an analysis using t.he
nine criteria of the NCP, EPA has selected Alternati-ve 3 as the Site remedy. The remedy consists of thefollowing components:
. Ground water in the shallow aquifer contaminated $rith arsenic at. leve1s above the ACL of S.O
mg/1, dissolved concentration will be addressed via source control and monitored natural
attenuation as follows:
1. source control wirl be implemented by excavation and off site disposal
of the principal threat hrasles at the Site, an estimated quantity of 2OOO
cubic yards of Category I materj-al defined in Section 9.1 of this ROD.
This material is considered a principal threat due to its high mobility and its
demonstrated ability to act as a source of ground r.rater contamination. In
addition, direct contact with this material- may result in acute human health
risks. Off site disposal will be conducted in accordance with EpA's off Site
Ru1e, 40 CFR 300.440 and the generator requirements idenuified in Table 17.
2. Further source control will be implemented by excavat.ion of
approximately 68,000 cubic yards of low Level threat waste, Category II
mat.erial defined in Section 9.1 of this ROD. This material will be
consolidated within a repository system const.ructed within the Site
boundaries in accordance rrith the ARARs identified 1n Tab1e 17. The
repository will be designed as the base for a new access road through the
site which was planned by Murray city. The access road is expected to be
the catalyst for Site development to commercial/retail uses.
3. Monitored natsural att.enuation wirr address the residuar ground rrater
contamination within and down gradient of these source areas. Monitored
natural attsenuation will continue until- shallow ground wat.er achieves theIevel of the ACL for dissolved arsenic of 5.0 mg/f,. the intermediate
aquifer will also be monitored to demonstrate continued compliance with
the MCL of 0.05 mg/1, dissolved arsenic.
4. The shallow agui-fer will be monitored t.o evaluate the concentrations of
selenium at the esta-blished compliance points south of Littl-e cottonwood
Creek. The selenium monitoring is not for evaluation of the remedy, it is to
ensure continued compliance with the selenium MCL.
5. Instituti-onal controls in the form of a Murray City ordj-nance
estabLj-shing an I'overlay district" and restrictive easements that n:n with the
fand which both will prohibit the construction of new we1ls or use ofexisting well-s within the on-facility area and the \,restarn and eastern
porti-ons of the off-facility area except for EpA approved monitoring we11s.
Surface soils (0"-2") within the on-facilit.y area contaminated with lead and arsenic
exceeding remediation levels of L200 mg/kg arsenic as the 95? upper confidence limit on thearithmetic mean within an EU or 5500 mg/kg lead as the arithmetic mean withj-n an EU will be
addressed as folfows:
1. SoiLs will be covered in place with barriers sufficient t.o prevent directcontact. Such barri_ers may be pavement, landscaping, soil caps, or
sidewal-ks. Site development itself is e>q>ected to result in additional
protect.ion of human health since land uses associated with unacceptable
human heal-th risks will end. Also, dewelopment wilr result in the
construction of additional- barriers (new buildi-ngs, roads, sidewal-ks parking
1ots, and landscaping) over remaining surface soil and slag.. Although no
unacceptable risks associated with oq>osure to slag were identified by
EPA, the development of the Site will ensure no exposure to slag in the future.
2. rnstituti-onaL controls i-n the form of a Murray City ordinance wi1l
establ-ish an I'overlay district" which incl-udes zoning to prevent residential
and contact intensive industrial uses wit.hin the former smelter operational
areas and will require maintenance of the barriers and controls on
excavated subsurface material wit,hin this same area. Restrictive easemenEs
than run with the land will be established in addition to the overlay districtto prevent residential or contact intensive industrial- uses.
off-facility surface soj-ls (0"-2") containing leveIs of lead exceeding 12oo mg/kg as thearithmetic mean in individual residential yards or 5500 mg/kg as the arithmetic mean in
commercial areas will be removed to a depth of 18 inches and replaced with clean fill. Anylandscaping disturbed in this action will be replaced. The removed soil will- be usedon-facili-ty as subgrade material- in construction of the repository system.
Surface water of Little cottonwood Creek wil-I be monitored to ensure continued protection
during the ground water natural- attenuation process at the level of lgo !g/L as a 4 day
average for trivalent arsenic and 350 ug/L as a t hour average for trival-ent arsenic and 100ug/t for dissolved arsenic.
The established ecological st.udy area will be monitored and the resulting information will
be used to reduce the uncertainties identified in the final Ecological. Risk Assessment forthe Site. Monitoring of wetLands will include surface $/ater, sediment and benthic macroinvertebrates. Monitoring of terrestrial areas will includ.e plants and soi1.
The goals of the selected remedy are to protect the intermediate and deep principal aguifer at the levelof the MCL for dissolwed arsenic, to restore the shal-l-ow gror,rnd water to the l-eveI of the ACL of 5.0 mg,/Lfor dissolved arsenic established to protect Little Cottonwood Creek at its beneficial use, and toremediate surface soils to levels protective of the reasonably anticipated future l-and use. The remedyincorporates the construction of a new north-south access road through the Site which will encouragefuture development of the Site and achieve Murray City's goal of more appropriate 1and use through sj_tedevelopment.
Based on information obtained during the Site investigat.ion and on a careful analysis of a1I remedialalternatives, EPA beliewes t.hat the sel-ect.ed remedy wil-L achieve Ehese goa]s. Iu may become apparentduring the monitored natural attenuation process for ground water that dissolved arsenic Iewe1s hawe
ceased to decline and are remaining constant at leve1s higher than the ACL over some portj-on of the pJ-ume\'/ithin the shal-Iow aquj-fer. If it is determined on the basis of system performance data that certainporcions of the aguifer cannot. be restored to the ACL, EPA will prepare a justification for a waiwer ofthe ground water ARAR based on tecLrrical- impracticability of achieving further contaminant reduct.ion.
1.0. Statutory Determinations
Under it.s legal authorities, EPA's primary responsibility at Superfund sites is to undertake remediaL
actions that achieve adequate protection of human health and the environment. In addition, section t2L ot
CERCLA establi.shes several other statutory requirementss and preferences. These specify that when
complete, the selecE.ed remedial action for.t,his Site must comply srith applicable or relevant and
appropriate environmental standards established under Federal- and State environmental laws r:nless a
statutory waiver is justified. The select.ed remedy al-so must be cost-effective and utilize permanent
solutions and alt.ernative t.reatment technologies or resource recovery technologies to the maximum extentpracticable. Fina11y, the statute includes a preference for remedies that. employ treatment that
permanently and significantly reduce the volume, toxicity, or mobility of hazardous wast.es as theirprincipal element. The folLowing sectj-ons discuss how the selected remedy meet.s these statutory
requirements.
10.1 Protectioa of Humaa Health aud t,be EnviroDrnent
The Baseline Human Health Risk Assessment identified r.rnacceptable risks over the entire on-facili.ty area
associated with potential direct cont.act with lead- and arsenic-contaminated soil and smelter debris by
workers engaged in outdoor industrial actj.vitj-es. The assessment identified substantially less risk(although still unacceptable in limited on-facility areas) associated with e>cposure to the same materj-als
under a scenario of commercial uses wherein workers would be primarily indoors. The assessment alsoidentified unacceptable risks associated rrith direct exposure to lead contaminated soil by residents and
commercial workers in the off-facili-ty area. Potential i-ngestion of ground water from the shallow aguiferwithin the Site boundaries was also predicted to result in r:nacceptable risk.
There j-s a large portion of the on-facility area where slag is e><posed at the surface. It is not 1ike1y
that commercial or industriaL workers or other adults will spend much time in areas of oq>osed s1ag.
Therefore, direct contact with slag by workers or residents is like1y to be minimal. However, area
teenagers have been observed to visit the site in areas where slagr is exposed. The Baseline Human Health
Risk Assessment characterized risks to teenagers who congregate in areas along lJittle Cottonwood Creek
and are potentially exposed to stag. The assessment concluded that risks associated with exposure to slag
are within the range that EpA considers to be acceptable.
The selected remedy employs ground water source control via excavation and off-site disposal of theprincipal threat at the site, undiluted arsenic trioxide, and will effectively address the identifj-ed
risk assocj-ated with potential migration of this material j.nto shallow grorlnd water and potential future
direct contact with this material-
The second component of the selected remedy is ground water source control by excavation and
consolidation of ground water source material within an on-site repository system. The system will be
desigrned with surface water management features. This action will effectively control the j.nfiltration of
surface water into arsenic contaminated soi.I and prevent further migration of arsenic into shallow ground
$rater. The on-Site repository system will be designed to perform as an adequate base for a new access
road from Vine Street to 5300 South Street. The repository thus will serve three functions in theprotection of human health at the Sj.te3
(1) Reduction of mobility of arsenic to ground water by off-Site disposal of and containment of ground
water source material to address risks associated with exposure to contaminated ground water;
(2) Containment of contaminated material which presents unacceptable risks due to direct contact thereby
eliminating this e>cposure pathway; and
(3) Catalyst for development of the Site by providing the base for a roadway which is e>q>ected to provide
the necessary access to promote commercial uses. The Site developments will address the unacceptable
risks associated wit.h high contact industrial outdoor activj_ties.
The t.hird component of t.he selected remedy is a comprehensive public and privat.e instituti.onal controls
package which will- restrict the use of ground water withj-n the Site boundaries (with the except.ion of EpA
approved monitoring weIIs) and restrict land uses other than general commerciaL uses as defined by the
Murray City land use code. The institutional controls package will also require that Site features such
as roads, parking 1ots, and landscaping, which are functioning as barriers to human e><posure be
maintained. The institutional controls will provide human heal-th protection into the future. The Site
development. itself is e>q>ected to result in protection of human health through the construction ofbarriers over remaining low leveI surface contamj-nation and s1ag. Although no unacceptable risks
associated with ercposure to slag were identified. the development of t.he site wil-I ensure no e)q)osure to
slag in the future.
The fourth component of the selected remedy is monitored natural attenuation of ground water down
gradient of source areas. Analyses performed during Site Characterizatj-on and summarized in the final
Site Characterization Report demonstrate thaE arsenic is being attenuated on the aguifer mat.erials and
that iron oxide is the primary mineral phase responsible for the attenuation of arsenic. Through E.he
adsorption mechanism, the unacceptably high levels of arsenic in the shallow aquifer will decrease over
time at a rate that depends on the net fl-ux of water moving through the affected portions of the shallow
aquifer. The process of adsorption will effectively reduce the dissolved arsenic concentrations in
shallow ground water. Performance monitoring will be implemented to evaluate the effectiveness of t.he
attenuation and to ensure prot.ection of human health and the environment. Performance monitoring will
include both ground water and surface water monitoring. The effects of ehe source control actions of
Al-ternative 3 along wiuh the monitoring activities are e>q)ected to demonstrat.e wit.hin 30-40 years
that the rate of natural attenuation of arsenic in shallow ground water is sufficient to predict that
the ACL will never be exceeded at the established compliance points near Little Cottonwood Creek. EPA
elq)ects the remaining areas of the shallow aquifer to achieve the ACL within a time frame of 100-L50
years.
The last component of the selected remedy is soil removal and replacement with clean fill in off-facility
residential or commercial properties with soil- lead concentrations that may present an unacceptable
health risk. This action will break the e:q>osure pathway of direct contact with soi1s.
L0.2 Complia-ce with Applicable or Relevant arrd Appropriate Requirements
The selected remedy will comply with all applicable or relevant and appropriate chemical reguirements
presented in Tables 16-l-8.
10.3 CoEt Bffectiveuess
The selected remedy is cost effective because it has been determined to provide overall
effectiveness proportional to its costs, the net present worth value being $11.6 miIlion. The estimated
costs of oEher alternatives are presented j-n Tab1es 19 and 20.
The costs of Alternatives 2,3, 6, and 7 are very simi.lar. Comparing Alternatsives 2 and 3, the additional
effectiveness and protect.iveness associated with off-site disposal of principal threat wastes
(Alternative 3) was judged to $rarrant. the additional $200,000 cost. The difference between Alternatives
3, 5, and 7 is the option for remediating the off-facility soi1s. The cost of a community monitoring and
heal-th education program is greater than the excavation of contaminated soils and provides an
approximately egual 1eve1 of protecti.veness. Alternative 7 includes tilling of soi1s. This Alternative is
less costly than fu11 soil removal but provides slightly less effectiveness in some areai of the Site.
The costs of Alternatives 3, 4, and 5 are quite different reflecting different approaches to ground watser
remediation. EPA hydrogeologists carefully considered the potential benefits of extracting and treating
ground water as described in Alternatj.ve 4. The effectiveness of this option is limited by the
characteristics of the aguifer which al1ow very litt1e erater to be extracted. The addition of an
extraction system will not increase the rate of improvement in ground water guality over natural
attenuation processes despite the additional cost. Also considered was the amoLrnt of land which would be
reguired for dedication of numerous gror:nd water extraction wel1s. This land would then be unavailable
for Site development. The additional cost of Alternative 4 does not result in effectiveness or benefit
for the Site. Alternative 4 also has greaEer problems rrith long term implementability, and greatser
incompatibility with Site development. Alternative 5 includes in-situ ground tater treatment in
additional to source controls. This alternative requires high operation and mainLenance costs without
appreciable increase in effectiveness or protectiveness.
Balancing costs with effectiveness, protectiveness, and Site development considerations, ALtsernative 3 is
judged by EPA to be the most cost effective.
10.4 Utilizatioa of Permarent Solutions .nd AlterDative Treatmeat Technologiea (or Resource Recovery
Technologles) to tsbe Maximum Extent Practicable
The selected remedy represents the maximum extent to which permanent solutions and treatment technol-ogies
can be utilized in a cost effective manner for the Site. Neither extsraction and treatment nor in situ
treatment of ground water were for.rnd to be more effecuive than natural attenuation at reducing arsenic
concentration in ground vrater. Yet both tsechnologies are more costly. The institutional controls of the
selected remedy, while not permanents, will provide tshe required leve1 of protection during the period of
natural attsenuat.j-on of the ground water. The source control measures will provide a permanent solution by
consolidatsing the matserial in a engineered repository system prevencing contact by water, and people.
of the alternat.ives that are protective of human health and the environment and comply !,rith ARARs, EPA
believes that the selected remedy provides the best balance in terms of long t.erm effectiveness and
permanence; reduction in toxicity, mobility, or volume achieved through treatment; short termeffectiveness; implementability; and cost. overall protection of human health and the envj-ronment, longterm effectiveness, and cost were t.he most. decisiwe criteria in selecting Alternative 3 as the remedy.
10.5 Preference for treat.mert, as a principal Elcment
The selected remedy prescribes excavation and off-site disposal for the principal threat rdaste. On-sitetreatment as a pri.ncipal element tas found not. to be cost effect.ive. However, the principal threat $rasteswill be treated off-sj-te before disposal. Therefore, the selected remedy satisfies the statutorypreference for treatment as a principal element t,o some degree.
Because the selected remedy will result. in hazardous substances remaining on site, a review will beconducted every five years after corunencement of remedial action to ensure that the remedy continues toprovide adequate protection of human health and the environmenE..
1.0.6 Coaclugion
EPA's choice of Alternative 3 for remediation of the site is protective of human health and the
environment and is in accordanee with CERCLA and the National Contingency plan.