PB98-964403
EPA 541-R98-078
October 1998
EPA Superfund
Record of Decision:
Murray Smelter
Murray City, UT
4/1/1998
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MURRAY SMELTER
PROPOSED NATIONAL PRIORITIES LIST SITE
MURRAY, UTAH
RECORD OF DECISION
CERCLIS ED UTD980951420
1. Site Name and Location
The Murray Smelter Site ("the Site") is located in the city of Murray, Utah, in Salt Lake
Counry 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-faciiity" area, as well as
surrounding residential and commercial areas where airborne emissions from the smellers
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-faciiity area is approximately 142 acres. Its boundaries are 5300 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-facility area is approximately 30 acres to the
west of the on-faciliry area, approximately 106 acres south and southeast of the on-faciiiry area,
and a small area between 5200 South Street and Little Cottonwood Creek to the east of the on-
faciiiry area. The west portion of the off-facility area is bounded by Little Cottonwood Creek to
the north, 300 West Street to the west, 5300 South Street to the south, and the on-faciiity
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-facility boundaries were determined by EPA based on
the results of air dispersion modeling performed in November, 1994. The purpose of the
modeling was to identity- the area that potentially would have received the greatest amount of
deposition resulting from lead and arsenic emissions from the Murray Smelter during its operating
?eriod.
For environmental sampling, risk assessment, and risk management purposes, the Site was
divided into smaller areas to represent realistic areas of human and ecological exposure. The 142
acre on-faciiity area was divided into eleven "exposure units" (EU'sl and the 136 acre off-facility
area was divided into eight "initial study zones" (ISZ's). The riparian area along Little
Cottonwood Creek was delineated as the ecological study are;.. The Site boundaries. EU's. and
ISZ's are shown on Figure 2.
2. Operational History
The Germania Smelter was built in 1872 or, the north west comer of the on-faciiity area
adiacen: to Little 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. Asarce was
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also constructing the Murray Smelter on property to the south and adjacent to the Germania
Smelter. In 1902, operations a; Germania stopped and the Murray Smelter began operating and
continued processing lead and silver ores until 1949. Smelting operations produced a variety of
by products including arsenic (as sulfates'oxides in flue dust or as arsenic trioxide), matte (an iron
sulfide matrix with high lead and copper content), arsenical speiss (an iron-arsenic-sulfide matrix),
and slag (a vitrified iron silicate).
The on-faciiiry portion of the Site includes both the former Germania Smelter and Murray
Smelter facility areas. Minimal specific information is available on the smelter operations at the
Germania facility. After operations ceased, the area was regraded with Germania slag and, later,
with slag from the Murray Smelter. Subsequently, no significant historical features of the
Germania Smelter remain and the description of smelter operations provided below is based solely
on descriptions of the Murray Smelter.
At the time of its construction, the Murray Smelter was reportedly the largest primary lead
smelter Li the world. In addition to lead, several byproducts were also generated including gold.
silver, copper, antimony, bismuth, arsenic, and cadmium. The main byproducts by volume were
slag, arsenic and cadmium.
Figure 3 is a layout of the Murray Smelter facilities. The Murray Smelter included an
extensive rail network, two stacks (330 feet and 455 feet high), eight blast furnaces, roasters,
arsenic kitchens, sinter plants, mills and power houses. The facility also included a baghouse for
emissions control. Most of the Murray Smelter facilities have been demolished, except for the
smelter stacks, some building foundations, and the original oSce/engine room building.
A flow sheet for Murray Smelter operations for 1920 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 snipped from various locations and was classified either as
sulfide ore or cxide ore. Oxide ore was capable of being smelted directly, whereas sulfide ore
required 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 -ulfur content of sulfide ores and to produce sintered material suitable for final smelting; and
('..'• smelting operations to produce lead bullion (shipped sway for final refining), matte (sent to
•.h. roasters to be treated again by oxidation of its sulfur), and slag. The secondary manufacturing
process was 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) four Dwight-Lloyd roasters; and (3) five Godfrey Roasters, operated in conjunction with
twenty-seven Huntington and Heberlein (''Hd:H") pots.
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The Wedge roasters received charge consisting ofsulfide 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-Lloyd roasters. Air emissions from the Wedge
furnaces passed directly into a dust chamber that ran along the north side of the Wedge roaster
building and connected the main roaster flue to the Cottrell Plant. The Dwight-Lloyd roasters, or
sintering machines, produced material which was transferred directly into rail cars and sent to the
roast bins where the blast furnace charge was made up. Air emissions from the Dwight-Lloyd
roasters were also sen: to the Cottrell Plant.
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 briquetted for charging to the blast furnace. Gases from the Cotrrell Plant
were sent to the 455-foot stack, which began operating in May 1918. 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
Plant. 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 relatively pure arsenic trioxide. Exit
gases from the kitchens were sent to the western portion of the baghouse and collected 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 1942, additions were made to the
arsenic kitchens to increase their production capacity (additional kitchens were added) and to
provide additional 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 Smehing Operations
Smelting was achieved by eight blast furnaces. The charge to the blast furnaces Included
oxide ore, flux material, and roasting products. Air emissions were sent to an enlarged flue, along
the west side of the building. From this chamber, the gases passed to a rectangular brick flue. 18
feet wide by 17 fe*r: high, which led to the baghouse. Exit gases from the baghouse were usually
sent to the 330 fjot stack, although gases from the baghouse or blast furnace were occasionally
routed to the 4'.? foot stack. The bachouse, installed in 1907, was constructed of brick 216 feet
long and 90 feet wide, and contained approximately 4,000 woolen bags, each 30 feet in length and
1S inches in diameter. In 1920, the 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
rail cars for transport to temporary storage areas near the thaw house where it was kept pnor to
off-site transport or conveyed to the Godfrey Roasters and arsenic kitchens by narrow gauge
railway for production of high-grade arsenic trioxide. The material from the baghouse was low-
Grade arsenic oxide, which contained lower amounts of arsenic than the arsenic kitchen p'oduct.
with arsenic oresen: ir. oxide and sulfate forms. Prior to off-site shipment, arsenic kitchen product
was stored in a wooden arsenic storage bin to the south east of the thaw house.
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2.3 Materials Used/Generated by the Smeher Operation
The contaminants of concern to human health at the Site are lead and arsenic1. Based on
the data generated at the Site and information on historic smelter operations, elevated levels of
arsenic and lead at the Site can reasonably be attributed tc the following materials:
• Lead Ore: No analytical data are available to describe the range of arsenic and
lead concentrations in ore materials processed at the smelters. Lead contents for
ore from Utah were reported between 4.4 and 32 percent by weight. Ore
mineralogy was variable, but may have included: galena, pyrite, arsenopyrite,
sphalerite, angiesite, cerussite, and lead oxide (massicot).
• Blast Furnace Products/By-products. Four materials were typically generated
during blast furnace operation: metallic lead, speiss, matte, and slag. The
materials would separate due to their varying densities. Metallic lead was the
primary product of the operation, and it is not expected that any quantity is
currently present at the Site.
• Matte/Speiss: In smelting of ores at the Murray Smelter, the amount of
speiss produced was too small to separate it from the matte. Matte/speiss
generated in the blast furnaces was comprised of metal sulndes, with iron
being the dominant metal. Analysis of speiss for various smelters in the
western U.S. show lead contents berween 0.5 and 2 percent and arsenic
contents between 31 and 32 percent. Analysis of matte at the same
smelters show lead contents between 8.5 and 18 percent and arsenic
contents below detection limits. Since speiss contents were probably small
a: Murray, it is believed that any material present at the Site will contain
higher levels of lead than arsenic. Lead matte'speiss concentrate was
riored out in the open in the northern plant area.
Slag: Slag is an amorphous, \i:rif\ed 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 still present at the Site. Lead concentrations of 8.200 to
16.000 milligrams per kilogram (me/kg) and arsenic concentrations of less
1 As will be discussed in subsequent sections of this ROD, contaminants of concern to
ecoiocical receptors within the ecological study area include other metals in addition to lead and
arsenic. However, the majority of the Site is suficiently characterized by focusing on lead and
arsenic.
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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 conditions. A series of leaching tests was
performed on a sample of slag material collected from the Site. The details
of the leaching tests and the results are summarized in the final Feasibility
Study. The tests indicate that a minimal proportion of the metals present is
released from slag when precipitation and ground water are the leaching
solutions. However, the release of arsenic appears significantly enhanced
at both extreme high and low pH.
Flue Dust: Roasting and furnace operations had a tendency' to volatiUze arsenic.
These gases were collected and transported in flues to treatment units, the Cottrell
Plan: or the baghouse. Exit gases from these units were sent to the stacks. Flue
dust is present in areas where operations were located (flues, the arsenic kitchens.
the Cottrell 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 wider area. This is due to dispersion resulting from spillage during material
handling, and stack emissions. Arsenic levels in flue dust have 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 primarily present in oxide forms
and some sulfate present. Pure arsenic trioxide has been measured at 760,000
mg/kg arsenic. Approximately 2000 cubic yards of arsenic trioxide have been
found in the on-faciliry area of the Site.
Stack Emissions: Exit gases from the baghouse and Cottrell Plants were routed to
the stacks Stack emissions resulted in the deposition of lead and arsenic onto
surface soils in the off-facility area. These emissions occurred during the entire
period of smeher operation. Lead levels in off-facility soils impacted by stack
emissions have been measured as high as 1800 mg/kg. Arsenic levels in these soils
have beer, measured ^, nigh as 610 rag/kg.
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 the resulting products and by-products were collected and
sold. Due to this sequenced shut down, the amount of residual raw materials, products, and by-
product left at the Site is limited. The exception is slag, the primary by-produc: of the smelting
process, which was initially present over z large area. The initial quantity has been significantly
reduced bv raining in the period since the smelter shut down.
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The majority of smelter structures were demolished in the period immediately after
operations ceased in 1949. Based on environmental sampling and historical photographs, it
appears that demolition of the main smelter structures was conducted in an organized manner.
Salvageable materials (e.g., metal from the processing units and rail lines, and other process
equipment) were taken off-site, and building structures were subsequently demolished with the
brick and concrete debris typically spread in the immediate area. Slag was then brought in from
the slag pile area to cover the debris and to provide a suitable surface for subsequent development
of commercial/manufacturing operations. 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
nil, residual materials such as fiue dust within footprints of former operations and mixed structural
debris from smelter demolition in the immediate vicinity of former structure locations . At a
limited number of locations, relatively high levels of arsenic such as that associated with flue dust
are present as deep as 10 feet. This is thought to be the 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 pan 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-faciiiry area is currently zoned Manufacturing General Conditional, M-G-C. This
zoning designation allows light industrial processes to be conducted with heavier industrial uses
allowed after a conditional use permit has beer, approved by Murray City. The majority of the on-
faciiiry area is owned by the Buehner family and leased by a concrete manufacturing company, the
unrelated Buehner Corporation. The company makes pre-cast and pre-stressed concrete building
and transportation products as well as arch'.ecrural concrete products. Other uses within the on-
faciiiry area include a pipe warehouse and. distribution facility, the W.R. White Company; a
telecommunications equipment compam, Skagcs Telecommunication Services; a Federal Express
outlet; the Murray City Police Training Facility; a portland cement transfer and supply facility,
Ashcrove Cement; other warehouses; and an abandoned asphalt plant owned by Monroe, Inc.
There are two residential trailer parks within the on-faciiiry area. The "Doc and Dell's" trailer
park is located on State Street. The "Granciview" tr_iier park is on the southwest corner of the
on-faciliry area on 5300 South Street. The locations of these trailer parks are noted on Figure 2.
Land use in the off-facility area is mixed residential/commercial. The western portion of
the off-faciiiry area is currently zoned M-G-C and Commercial Development Conditional. C-D-C.
C-D-C zoning provides areas where a combination of businesses, commercial, entertainment and
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related activities may be established and maintained. The southern portion of the off-facility area
is currently zoned M-G-C and low density single family residential, R-l-8. The Murray Junior
High School and the Murray High School are located in the south portion of the off-facility area.
3.1.2 Future Land Use
In 1997, the Murray City council adopted a land use plan for future development of the
on-faciliry portion of the Site and amended its General Plan accordingly. The land use plan for
the en-facility area includes construction of a north-south roadway corridor from Vine Street to
5300 South Street through the central 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
alignment shown in Figure 5. This alignment takes into 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-facility area is highly likely to be redeveloped in
the near future. Current land owners are discussing options with the City and potential
developers to optimize future use of the area. Much or all of the outdoor industrial activity is
expected to end, to be replaced with light industrial/ commercial activities. The City will
rezone the area to C-D-C use by passing an ordinance establishing an "overlay district" which
restricts certain uses and requires city review of development plans within the on-faciliry 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 Dell'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 (UTA) and residential leases are not being renewed. UTA
intends to swap the Grandview parcel for a parcel of land owned by the Buehner family near
Ashgrove. Within two years, UTA will construct a light rail station platform adjacent to the
existing railroad tracks along with associated off-street parking and landscaping. If the land
swap with Buehner occurs, then residential occupation of Grandview will be terminated more
rapidly as the site is developed. In either case, residential occupation of Grandview will likely
end within two years.
The .Amendment to the General Plan for Murrs} City also includes three other potential
public use projects:
1) Murray Cin Court/Police Administrative Office. There is interest in
locating a court-police complex somewhere south of Lirtle Cottonwood Creek,
and south of Vine Street. The City will be establishing its own court system
within a few vears and will ultimately need facilities to be constructed for this
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purpose. There is an urgent need to provide adequate police facilities as well as
additional space in City Hall. It is anticipated that three to five acres will be
needed for this facility.
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2) Little Cottonwood Creek Parkway Improvements. The Murray Parks &
Recreation Department is interested ic obtaining property to enhance the south
side of Little Cottonwood Creek with landscaping, a walking and bicycle trail,
urban plaza, pavilion and restroom facilities contained within approximately 5
acres. This would allow the extension of the City's existing trail system with a
target of connecting to the Jordan River trail system.
3) Smelter Site Interpretive Park. There is also interest in developing a small
interpretive park at the base of the smelter stacks that would be no larger than
approximately two acres. The small park could contain a plaza, seating,
fountain and landscaped areas. Historical information relating to the smelter
Site history would be integrated into the park development.
This type of development provides the opportunity to integrate implementation of
remedial actions into development activities, a key objective of EPA's Brownfields Program.
Given the interest in developing the on-faciliry area and the high level of involvement and
commitment by the City of Murray and the current land owners, there is sufficient certainty
concerning future land use to identify the reasonably anticipated 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 oa-facility area is light
industrial/commercial use.
In the off-facility area, areas to the west of the on-facility area (ISZ-1 and ISZ-8) are
zoned M-G-C and C-D-C but do have some residential occupation. This zoning prevents the
construction of new homes, and therefore, residential occupation is expected to end in the
future. To the south of the on-facility area (ISZ-6 and ISZ-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 existing non-conforming residences, residential occupation is expected
to end sometime in the future due to the prohibition of new home construction and the
redevelopment of the on-faciiity area. The reasonably anticipated future land use for the o£F-
facility area is a combination of commercial/light industrial and residential.
3.2 Topography
The Site is mainly flat in the southern portions. Near Little Cottonwood Creek on the
north, the terrain slopes steeply. This area used to be filled with slag from the Murray Smelter but
over the years since the smelter shut down, the slag has been excavated and used throughout the
Salt Lake Valley. A steep wall of concrete debris from recent Site uses and residual siag remains
in the northern area where slae used to exist.
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3.3 Geologic Units and Soils
The geologic units at the Site consist primarily of lake sediments from Pleistocene Lake
Bonneville, however, younger alluvial floodplain deposits are found along Little Cottonwood
Creek. The lake sediments consist of clays, silts, and fine sands and underlie the more recent
alluvial stream deposits which generally consist of silt, sand, and gravel. Surface soils within the
on-facility portion of the Site have been disturbed, affected by the construction and operation of
smelting, ore handling, and refining facilities over a period of 77 years. In more recent times,
construction and operation of concrete, asphalt, and other commercial or manufacturing facilities
have further disturbed the area's soils. In particular, construction of the facilities and the
deposition of slag from smelting operations and other fill materials have covered the majority of
the original surface soils.
In the off-facility area, surface soils have been signif :am!y affected by extensive general
urban development.
3.4 Hydrogeology
Tne Site lies on an area covered by thick valley-fill (alluvial) deposits that comprise several
distinct aquifers within the aquifer system. Specific components of the aquifer system are as
follows:
• Shallow Aquifer, a shallow, unconfined aquifer comprised of interbedded sandy
clays and clayey sands occurring above the Bonneviile Blue Clay;
Bonneville Bhie Clay: approximately 30-foot-thick continuous layer of clay
separating the shallow and Intermediate aquifers;
• Intermediate Aquifer, a confined aquifer immediately underlying the Bonneville
Blue Ciay comprising approximately 10 to 20 fee: of relatively coarse-grained
deposits: and
• Deep Aquifer: an artesian aquifer, several hundred feet beiov the intermediate
aquifer, comprising various coarse-grained valley-nil deposhs
The shallow aquifer is unconfined with a saturated thickness that ranges from 2.5 to 25
feet within the on-faciiiry area. The average depth to water is approximately 10 feet. The aquifer
materials have a geometric mean hydraulic conductivity of 5 feet per day (based on estimates from
different locations in the study area ranging from 1 to 112 feevday). Groundwater in the shallow
aquifer flows along the top of the Bonneville Blue Clay, generally north-northeast, toward Little
Cortonwood Creek as showr. in Figure 6. Water levels measured adjacent to the creek indicate
that the shallow aquifer is hydraulicaliy connected to Little Cortonwood Creek and that
Ground water discharce to the creek occurs during certain times of the year.
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The second component of the aquifer system is the BonnevilJe Blue Clay. Available
hydrogeologic information 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 aquifer to the intermediate and deep aquifers. Analyses presented in
the Feasibility Study support this conclusion.
Beneath the Bonnevilie Blue Clay, the intermediate and deep aquifers are separated by
more than 200 feet of interbedded fine- and coarse-grained valley-fill and alluvial deposits. Both
receive recharge primarily up gradient of the Site. Groundwater in the intermediate aquifer flows
north-northwest across the Site as shown in Figure 7, and the aquifer is not hydraulically
connected to surface water bodies in the vicinity of the Site. The deep aquifer is the main source
of drinking water for most residents in the Salt Lake Valley. Municipal water-supply wells
located in the vicinity of the Site are screened more than 500 feet below the ground surface in the
deep aquifer.
3.4.1 Potential for Use of Ground Water as a Drinking Water Supply
It is unlikely that the shallow aquifer will ever be used as a potable water supply due to
several conditions. Primarily, the water is of poor quality for drinking water. Background total
dissolved solids (TDS) concentrations range from 606 to 3,236 mg/L and exceed EPA's
secondary drinking water quality standard of 500 mg.'L. Additionally, this water supply is only
available in limited quantity- due to the aquifer thickness coupled with low hydraulic conductivities
which do not produce sufficient water for typical water supply needs. The intermediate and deep
aquifers provide lower TDS and higher yielding water suppb'es. However, within EPA's ground
water classification system, two factors are considered in designating ground water as a potential
drinking water source; water quality' and yield. In EPA's regulatory scheme, water is considered
to be suitable for drinking if it has a TDS concentration of less 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 characteristics of both the shallow aquifer and the intermediate aquifer at the Site meet
EPA's criteria for designation as a potential drinking water source, Class lib and Utah's criteria
for designation as z. Class 13 drinking water under Utah's Ground Water Quality Protection Rule.
The deep aquifer meets both EPA's and Utah's criteria for designation as a Class I aquifer, a
current drinking water source.
3.5 Surface Water
Little Cottonwood Creek is a perennial stream flowing along the north/northeast boundary
of the on-facility area and into the Jordan River approximately one mile downstream. The stream
has been altered by urban and agricultural development both upstream and downstream of the
Site. In the northern portion of the on-facility area, the course of the stream was altered during
smeller operation. Facility drawings and aerial photographs indicate that the creek originally
fiowed through the northern portion of the on-faciiity area, but during smelter operation the creek
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was diverted to the north with the former channel incorporated into the slag pile. Today, the
upstream reaches of the creek are bordered by residential areas or parks, while the Site and
downstream reaches are mainly bordered by commercial/industrial areas.
Historically, Little Cottonwood Creek has been stocked with rainbow trout and German
brown trout; 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. In the vicinity of
the Site, Little Cottonwood Creek is designated by the State of Utah for secondary contact
recreation use such as boating and wading (classification 2B), for cold water game fish use
(classification 3 A) and agricultural use (classification 4). A survey of Little Cottonwood
Creek conducted in 1997 found no diversions of surface water for agricultural use
downgradient of the Site. Although no formal petition has been brought forward to the Utah
Water Quality Board to change the agricultural use designation, existing evidence documented
in the survey report suggests that such use is not likely in the future.
In addition to the use designations assigned by the State of Utah, fisheries habitat in
Utah is inventoried and classified on a statewide basis by the Utah Division of Wildlife
Resources. The section of stream near the Murray Smelter has been designated as a Class 5
stream based on esthetics, availability, and productivity as determined in 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 waters in this class could provide
valuable fisheries if sufficient quantity of water could be provided.
On the northern area of the Site, shallow ground water within the floodplain of Little
Cottonwood Creek surfaces at three distinct locations to form wetlands. An area of 0.75 acres
of wetlands were identified in a delineation study done in June, 1997 by Hydrometrics titled
"Report of Wetland Determination, Little Cottonwood Creek Riparian Area, Former Murray
Smelter Site, Murray, Utah".
3.6 Climate
The Salt Lake area has a semi-arid climate. Average precipitation is approximately 16
inches per year and the average air temperature is approximately 64 degrees Fahrenheit. Tfa;
Site elevation is approximately 4280 - 4315 feet above sea level.
3.7 Floodplain
The most recent flood insurance study which includes Lirtie Cottonwood Creek was done
by HUD in 1994. Several differences have been observed between existing fioodplain topography
and the floodplain cross section data utilized for development of the most recent floodplain map.
Existing conditions, compared with conditions from which previous floodplain delineations were
based, show more floodplain area in the southbank (within the on-faciliry area) and less flood
plain area in the northbank (north of the Site boundary). The larger existing southbank fioodplain
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area probably resulted from excavation of slag from this area, or it may have been excluded from
previous studies because it may not be part of the effective flow conveyance. Most of the site is
outside of the 100 year floodplain as shown on Figure 8 from the HUD study.
3.8 Nearby Populations and Demographics
Based on data from the 1990 census, approximately 20,000 people live within a mile
radius of the Site. The majority of this population is non-minority. Of the 20,000, there are
approximately 2,100 children 5 years old or younger, 2,700 adults over the age of 60, and 4,200
women of child-bearing age (18-45 years old). Figure 9 summarizes this demographic
information.
4 Site History and Enforcement Activities
4.1 Administrative Order on Consent for an Engineering Evaluation/Cost Analysis
In January, 1994, EPA proposed that the Site be listed on the National Priorities List. On
August 5, 1994, EPA issued a letter of "Notice of Potential Liability and Demand for Payment"
to Asarco. Negotiations between EPA and Asarco commenced shortly thereafter culminating in
September, 1995 when EPA, Asarco, and Murray City entered into an Administrative Order on
Consent (AOC) for the performance of an Engineering Evaluation/Cost Analysis (EE/CA) for the
Site. EPA retained 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, 1995, 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 within and adjacent to the playground which
contained unacceptable levels of lead and arsenic and backfill of those areas with clean nil. This
removal action was completed by Asarco in November, 1995. The removed soils have been
temporarily stored in a waste pile on-Site and will be consolidated on-Site as pan of the remedial
action selected in this ROD.
4.3 Memorandum of Understanding with Murray 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.
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4.4 EE/CA
Data needs were identified in the EE/CA Work plan, an attachment to the EE/CA AOC.
Environmental sampling to support the EE/CA and risk assessments began in April 1995. Asarco
completed a Site Characterization Report in August, 1996. Shortly thereafter, EPA decided to
redirect what had been a Non-Time-Critical Removal activity into the remedial action framework.
Accordingly, the requirement for an EE/CA was changed to a Feasibility Study. Table 1 shows
the completion dates for the major documents which support this Record of Decision (ROD).
DOCUMENT
Site Characterization Report
Baseline Human Health Risk
Assessment
Feasibility Study Report
Baseline Ecological Risk
Assessment
Proposed Plan
RESPONSIBILITY
Asarco
EPA
Asarco
EPA
EPA
COMPLETION DATE
August, 1996
May, 1997
August, 1997
September, 1997
September. 1997
Table 1: Completion Dates for Major Documents Supporting the ROD
4.5 Information Requests
EPA sent CERCLA 104(e) requests to Asarco and on-facility property owners by letter
dated April 25, 1996 seeking information on operations at the Site and material handling and
storage details. Responses to the information requests were provided by all recipients.
5. Scope of Response Action
The remedial action which is the subject of this ROD is the second of the three 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 levels considered by EPA to be
unacceptably high. The area was backfilled with clean fill. 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 critical removal action in
November, 1995.
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The remedial action described in this ROD addresses contaminated ground water, the
subsurface soil which is the source of the ground water contamination, contaminated surface soils,
and the surface water of Little Cottonwood Creek as follows:
1. Contaminated ground water. Source control will be implemented by excavation and
off-site disposal of the principal threat wastes at the Site, approximately 2000 cubic yards
of residual undiluted arsenic trioxide. This material is considered a principal threat due to
its high mobility and its demonstrated ability to act as a source of ground water
contamination. In addition, direct contact with this material may result in acute human
health risks. Further source control will be implemented by excavation of approximately
68,000 cubic yards of low level threat waste, diluted arsenic trioxide or flue dust mixed
with soil, fill, or debris from former smelter structures. This material will be consolidated
within a repository system constructed within the Site boundaries. 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. Monitored
natural attenuation will address the residual ground water contamination within and down
gradient of these source areas. Institutional controls in the form of a Murray City
ordinance establishing an "overlay district" and restrictive easements that run with the land
both will prohibit the construction of new wells or use of existing wells (except EPA
approved monitoring wells) within the on-facility area and the western and eastern
portions of the off-facility area.
2. Contaminated surface soils. On-facility surface soil containing levels of lead and
arsenic which exceed remediation levels will be covered. The barriers will provide
protection by breaking the exposure pathways associated with long term direct contact
with these soils. Site development itself is expected to result in additional protection of
human health since land uses associated with unacceptable human health risks will end.
Also, the development will result in the construction of additional barriers (new buildings,
roads, sidewalks parking lots, and landscaping) over remaining surface soil and slag.
Although no unacceptable risks associated with exposure to slag were identified by EPA,
the development of the Site will ensure no exposure to slag in the future. Institutional
controls in the form of a Murray City ordinance will establish an "overlay district" which
includes zoning to prevent residential and contact intensive industrial uses within the
former smelter operational areas and will require maintenance of the barriers and controls
on excavated subsurface material within this same area. Restrictive easements that run
with the land will be established in addition to the overlay district to prevent residential or
contact intensive industrial uses.
05"-facility surface soils containing levels of lead exceeding remediation levels will be
removed and replaced with clean nil. The removed soil wil] be used on-faciiiry as
subcrade material in construction of the reoositorv svstem.
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3. Surface water. Little Cottonwood Creek, which forms the northern boundary of the
Site and to which shallow ground water discharges, will be monitored 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.
The remedial action protects ground water and Little Cottonwood Creek and incorporates
the construction of a new north-south access road through the site which will encourage future
development of the Site and help achieve Murray City's goal of more appropriate land use through
site development. Institutional controls will prevent exposure of people to ground water with
arsenic concentrations that represent an unacceptable risk and will also ensure that future uses of
the land will be protective and that the remediation will be maintained.
EPA expects that an additional response action will be required at the Site. A structural
analysis of the existing stacks at the Site was completed in January, 1998. The study concludes
that both stacks as they exist today are not able to withstand seismic events which are specified in
the current Uniform Building Code. Based on information collected as part of Site
characterization efforts on the nature and extent of contamination on interior bricks of the stacks,
EPA expects that an additional time critical removal action will be required to address the
potential for release of hazardous substances and resulting health risks associated with the
potential structural failure of the stacks.
6. Highlights of Community Participation
EPA's community involvement activities at the Site began in March, 1995 with the
establishment of the information repository at the Murray City Library. In August, 1995, when
the EE/CA work pian was in final preparation, EPA and UDEQ released a fact sheet describing
the scope and objectives of the site investigation. With the assistance of Murray City officials,
two public meetings were conducted on August 9, 1995 and August 10, 1995 to inform the
ected citizens of Murray about the upcoming investigation activities on or near their property.
in September. 1996. EPA released another fact sheet describing the preliminary results of
:he baseiine human health and ecological risk assessments. Since the results were specific to
separate populations, EPA conducted six separate public meetings and two availability sessions to
explain the results of environmental sampling and risk assessments.
In October. 1996. EPA initiated the formation of the Murray Smelter Working 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 alternative cleanup strategies for the
on-faciiity area of the Site. In a series of open meetings conducted during October, 1996 through
February. 1997. implications of remedial alternatives were discussed by the working group. EPA
provided information on the nature and extent of contamination and the clean up requirements.
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The following commitments were made as a result of the Working Group sessions:
1. Current property owners, Murray City, and Asarco are committed to accomplishing the
necessary tasks to ensure that a new road will be constructed on the Site between Vine
Street and 5300 South Street. These tasks include dedication of the land for the road right
of way and agreement on the establishment 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 the members of the Murray Smelter Working Group are
memorialized in an Agreement in Principle signed in May, 1997.
In September. 1997, EPA released the Proposed Plan for the Site and made available all
supporting documents in the information 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 Salt Lake City Tribune and the Deseret News
on September 23, 1997. A public comment period was held from September 22, 1997 until
October 22, 1997. In addition, a public meeting was held on October 1, 1997. Responses to the
comments received during the public comment period are included in the Responsiveness
Summary which is part of this ROD. A summary of the highlights of community participation is
presented in Table 2.
This decision document presents the selected remedial action for the Murray Smelter Site
in Murray. Utah, chosen in accordance with CERCLA and the National Contingency Plan. The
decision for this Site is based on the administrative record.
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ALWVU'Y
Fact Sheet
Public Meeting
Fact Sheet
Public Meetings.' Availability
Sessions
Murray Smelter Working
Group Sessions
Fact Sheet
Public Meeting
Public Comment Period
SUBJECT
summary of site investigation
activities
explanation of sampling
activities
draft risk assessment release
draft risk assessment and
sampling results
future site use plans and
remediation alternatives
Proposed Plan of Action
comments on the Prooosed
Plan
Proposed Plan of Action
DATE
August. 1995
August 9-10, 1995
September. 1996
September, 1996
October, 1 996 - February,
1997
September, 1997
October, 1997
September 22 - October 22,
1997
Table 2: Highlights of Community Participation Activities
7 Summary of Site Characteristics
7.1 Scope of She Investigation Activities
Using data available from Preliminary Assessrnent'Site Investigation activities. EPA
Derformed screerung level calculations to identify the chemicals of concern which would be the
focus of site ch.Macterization, risk assessment, and remedial activities at the Site. This analysis is
documented in the "Preliminary Scoping P»eport" prepared by EPA in December, 1994. The
analysis concludes that lead and arsenic are the chemicals likely to be of substantial concern to
humans. Based on these results, the EE/CA Work Plan specified lead and arsenic chemical
analysis of soil and ground water samples collected to support site characterization and the
biseiir.e human health risk assessment. Recognizing that chemicals of concern to ecological
receptors, especially aquatic organisms, often are different from those of concern to humans. EPA
selected the ecological chemicals of concern by evaluating historical data collected from surface
water, sediment, and soil in the Little Cottonwood Creek riparian zone. This evaluation was done
bv the EPA Pvegion 8 Ecological Technical Assistance Group (ETAG) at a meeting on January
3 1. 1995. In addition to arsenic and lead, the ETAG identified aluminum, cadmium, copper.
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mercury, nickel, selenium, stiver, thallium, and zinc as ecological chemicals of concern to be
investigated in the ecological study area.
7.2 Soil and Dust Investigation
The site investigation for surface soil, subsurface soil, and dust is detailed in the Final
EE/CA Work Plan completed in September, 1995. Prior to sampling, the on-facility area was
divided into eleven EUs based on current property boundaries and land use. Similarly, the off-
facility area was divided into eight ISZs based on consideration of the predicted pattern of historic
air deposition from the site along with 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 exposure units. In addition, test pits were excavated in
several exposure units, using existir^: and historical features to select the location of the pits.
Special emphasis was placed on areas where potential sources of contamination such as historical
locations of the smelter flues, the bag house, waste transfer facilities, the roasting areas, the
arsenic kitchen, and the smelting areas were located. At each test pit, subsurface samples were
collected in one foot intervals to a depth of 5 feet.
In the off-faciiiry area, surface soil samples were collected from 10 to 16 distinct
residential yards (depending on the size of the ISZ) within each ISZ. Each sample was a
composite of surface soil from 4 to 6 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 0"-2", 2"-6", 6"-12" and 12"-18" intervals. These subsurface samples were collected to
characterize the vertical extent of contamination in each off-facility ISZ. Indoor dust samples
were collected from 22 different homes or buildings in the off-facility areas. Samples were
collected using a hand held vacuum. Typically, each sample was a composite of dust collected
from three areas, each about 2 feet by 7 feet. Summaries of sampling results for soil and dust can
be found in Tables 3-5.
After the Baseline Human Health Risk Assessment was completed, supplemental soil
sampling was conducted in every residential yard within those ISZs which were predicted to have
unacceptable risk. A. j.ummary of this supplemental sampling effort can be found on Figures 10-
CHEMICAL
Arsenic
Lead
# OF SAMPLES
22
21
AVERAGE
RANGE
27 mg'kg 1 5 mg/kg - 94mg/kg
303 mc'lce
83 mc'kc - 757mc.'kc
Table 3: Summary- Statistics for Indoor Dust Samples
In order to gain information on the physical and chemical nature of the lead and arsenic
present ir. surface soil. EPA collected 10 samples from locations on the Site. These samples were
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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 variety of different forms, most
commonly as lead phosphates, lead silicates, lead oxides, iron-lead oxides, lead arsenic oxide, and
lead sulfide. In contrast, arsenic occurs mainly as ferric-lead-arsenic oxide and lead-arsenic oxide
with only small amounts of other arsenic species. The lead and arsenic bearing panicles were
mainly smaller than 20 um with about 80% of all the lead or arsenic bearing grains existing in a
liberated or cemented state, with only about 20% existing within a rock or glass matrix.
7.3 Slag Investigation
EPA collected a single composite sample of slag from nine different locations at the Site.
Two of the subsamples were from the Germania smelter slag pile, six were from the face of the
slag monolith located adjacent to EU-2, and one was from the slag at the base of the slag pile
adjacent to Doc and Dell's trailer park. The composite slag sample was analyzed in duplicate
using Contract Laboratory Program methods. The mean values of the duplicate analyses are
695 mg/kg arsenic and 11,500 mg/kg lead.
In addition to chemical analysis, the slag sample was submitted for geochemical
characterization. As expected, the principle form of lead-bearing panicle in the slag sample is slag
(i.e., panicles of glassy matrix with lead dissolved in the glassy phase). However, this type of
panicle contains a relatively low concentration of lead and so does not account for most of the
lead mass in the sample. Feather, the majority of the relative lead mass exists in the form of lead
oxide with smaller contributions from galena (9%), lead arsenic oxide (6%) and other metal lead
oxides (4%). About 87% of all lead bearing panicles in the slag sample are liberated, accounting
for about 77% of the relative lead mass.
Similarly, the most frequent type of arsenic bearing panicle in the slag sample is slag,
accounting for 62% of the relative arsenic mass. The majority of these panicles are liberated,
existing panially or entirely outside the confines of glassy slag panicles.
7.4 Ground Water Investigation
The ground water investigation was conducted in two phases which included installation
of 13 monitoring wells in the sha'Io'1' aquifer, 7 monitoring welis in the intermediate aquifer
(Phase I), and a hydropunch investigation (Phase n). Several other on-facility wells that had been
installed in earlier investigations were also redeveloped and sampled. A presentation of the
results of all the ground water sampling performed between October, 1995 and April, 1996 is
contained in the final Site Characterization Repon. Shallow alluvial and intermediate ground
water continues to be monitored quanerly. Summaries of the sampling results for key anaiytes in
shallow ground water can be found in Table 6. A full summary of all ground water sampling
results can be found in the October. 1997 Ground Water and Surface Water Monitoring Repon
The most severe Site-related impact to shallow ground water was found to be arsenic
contamination. Figure 6 illustrates the arsenic levels detected in shallow ground water ir.
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January, 1996. Distinct plumes of contamination can be seer, in areas underlying the former
locations of smelter operations.
7.5 Surface Water, Sediment, and Riparian Soil Investigation
Samples of surface water, sediment, benthic macroinvertebrates. and riparian soil were
collected in the ecological study area and analyzed for ecological chemicals of concern as pan of
site characterization efforts. Figure !3 shows the locations of these samples. Summaries of the
results of this sampling can be found in Tables 7-10.
Subsequent to site characterization efforts, additional quarterly surface water sampling
was conducted beginning in July, 1996. Additional locations were established to characterize
areas of Little Cottonwood Creek which receive ground water discharge from the shallow aquifer
and to characterize the effects of-ground water and point source discharges or the water quality
of Little Cottonwood Creek. Figure 13a shows these additional locations. This supplemental
sampling was limited to arsenic analysis. Summaries of the surface water results can be found in
Table 11.
The results of the point source discharge sampling are particularly significant because they
indicate that the increase in dissolved arsenic concentrations in Little Cottonwood Creek occurs in
the vicinity of the discharge from a storm sewer culvert running north along State Street.
Loading calculations presented in the April, 1997 quarterly monitoring report demonstrate that
nearly all of the dissolved arsenic loading (88%-100%; accounting for flow measurement
accuracy) observed in the creek appears to originate from the culvert point source discharge.
Ground water discharge from the shallow aquifer in the on-facility area to the south of the creek
was not shown to have a measurable effect on arsenic load in the creek.
8. Summary of Site Risks and Remedial Action Objectives
8.1 Human Health Risks
EPA completed a baseline risk assessment for the Site in May, 1997. Human health 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-faciiity 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 activities that result in significant exposure to soil and
dust ^contact intensive (C!) workers); and teenagers who have been observed congregating in
areas along Little Cononwood Creek. The exposure pathways evaluated for each group were
ingestion of soil and dust, ingestion of slag (only evaluated for current and future teenagers), and
ingestion of ground water. Other exposure pathways to site-related wastes are judged to be
sufficiently minor that quantitative evaluation was not warranted. The current land use for the site
is a combination of commercial (best represented by NCI workers), industrial (best represented by
CI worke-s), and residential. As discussed in Section 3, the reasonably anticipated future land use
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for the on-faciliry area is commercial/light industrial (NCI) and for the off-facility area is a
combination of commercial/light industrial (NCI) and residential. The exposure assumptions
used in the risk assessment were also used to develop preliminary remediation goals for soil.
Tnese assumptions can be found in Appendix B.
The risk assessment was performed using two distinct approaches for the on-facility and
off-facility portions of the Site. The majority of the 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 soils during a working lifetime. The residential trailer parks within the on-facility
area were divided into four smaller EUs sized to approximate the area over which a child or adult
might come in contact with soil during the period of residence. Soil samples were collected
within each exposure unit and averaged according to EPA guidance. This average, the "exposure
point concentration", was the basis for the risk calculation. EPA will manage risks for the on-
faciiity area by EU.
In contrast, the off-facility was divided into eight ISZs sized to represent neighborhoods,
not individual residences. This was because historical data indicated little variability in
concentrations of lead and arsenic within neighborhoods. Concentrations in general tended to
decrease with distance from the smelter site. The term ISZ was chosen deliberately to reflect that
the risk assessment for the off-facility area is an "initial" or screening level assessment. The
exposure point concentrations for the off-facility risk assessment were the average concentrations
for each ISZ or neighborhood. EPA established the following decision rule for the off-facility1:
If the screening level risk assessment predicts unacceptable risks in a given ISZ, the assessment
will be refined (i.e., additional samples will be collected to characterize each residence, exposure
point concentrations will be established based on these samples and will be compared to the
remediation goal), if the screening level risk assessment predicts acceptable risks in a given ISZ,
that ISZ is considered to require no further action. Based on this decision rule, additional soil
samples were collected from each residence within ISZ 1, 6, and 7. The refinement of the
screening level assessment was completed after this supplemental soil sampling was performed in
ISZs 1, 6 and 7 in January, 1997. A comparison of these sampling results with the 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.
8.1.1 Arsenic Posts
The risks associated with exposure to arsenic in soil are summarized in Table 12 excerpted
from the final Human Health Baseline Risk Assessment. Current EPA policy, summarized in
OSV\"ER Directive 9355.0-30, 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 10"*, and the non-carcinogenic hazard quotient is less than 1, action is generally not
warranted . Using this criteria, the cancer and non-cancer risks associated with the reasonable
maximum exposure to arsenic in soil by NCI workers are predicted to be unacceptable in ('i.e.,
warranting remedial action) ir. EU-3 and EU-4 oniv. The cancer and non-cancer risks associated
21
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with the reasonable maximum exposure to arsenic in soil by CI workers are predicted to be
unacceptable in all exposure units. The cancer and non-cancer risks associated with the
reasonable maximum exposure to arsenic by residents within the on-faciliry area are unacceptable
in one exposure unit, EU-S. As can be seen in Figure 2, EU-8 is adjacent to areas where people
are currently living. However, no trailers are present and no people currently reside within this
EU.
In the off-facility area, risks to residents are unacceptable in ISZ-8. Close inspection of
ISZ-8 reveals that the unacceptable risk is attributable to one property. The risk assessment
broadly assumed that all off-facility properties were used as residences. This particular property
is used for a commercial business (it is a lumber yard) and is expected to remain in commercial
use in the future. Comparison of soil concentrations to those considered to be acceptable for NCI
workers demonstrates that risks are acceptable for commercial use of this property.
The risks associated with the reasonable maximum exposure to arsenic in ground water
are summarized in Table 13 excerpted from the final Human Health Baseline Risk Assessment.
As can be seen in the table, the non-cancer and cancer risks associated with exposure to arsenic in
ground water are unacceptable for both workers and residents.
The risk assessment also evaluated the potential risks associated with exposure of
teenagers to slag while visiting the Site. The cancer and non-cancer risks associated with the
reasonable maximum exposure to arsenic in slag are below a level of concern. The hazard
quotient is 0.2 and the cancer risk is 1 xlO'5.
8.1.2 LeadRisks
The health risks associated with exposure to lead are evaluated in a different manner than
those associated with exposure to arsenic. The health effect of most concern associated with lead
exposure is the impairment of the nervous system, especially in young children and unborn
children. Analyses conducted by the Centers for Disease Control and EPA associate levels of lead
ir. the blood of 10 micrograms per deciliter (ug/dL) and higher with health effects in children.
EPA's risk management goal for lead is to achieve a level of p:0tectiveness such that a rypical
child or group of similarly exposed children would have an r.,:imated risk of no more than 5% of
exceeding the 10 ug/dL blood lead level. The risk assessment results for lead exposure a; the
Site are reported as the probability of an individual child or the fetus of an individual pregnant
worker having a blood level above the 10 ug/dL goal. EPA's Integrated Exposure/Uptake
3iokinetic Model was used to assess risks to residential children. A biokinetic slope factor
approach was used to assess risks to adults and teenagers. The risk assessment considered the
exposed population within the on-facility EUs 1-7 to be adults.
The health risks associated with exposure to lead in soils at the Site are summarized in
Tables 14 and 15 excerpted from the final Human Health Baseline Risk Assessment. Risks ;o
NCI workers are predicted to exceed EPA's health goals in EU-3 only. However, the health r.sks
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associated with exposure to lead in soils by CI workers exceed EPA's health goals in all exposure
units, with probabilities of 25%-99% of exceeding the target blood lead level. The risks from
exposure to lead within the on-faciiiry residential areas of EU 8, 9 and 11 are predicted to exceed
EPA's health goals. In the residential areas south and west of the site, risks from exposure to
lead exceed EPA's health goals in ISZ-1, ISZ-3, ISZ-6, ISZ-7, and ISZ-8. Close 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 commercial
properties. 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 ISZ-1, ISZ-6, and ISZ-7.'
The risk assessment also evaluated the potential effect of the exposure of teenagers to slag
while visiting the Site. The assessment concluded that there is a less than 0.02% probability of
exceeding EPA's health based goal as a result of this exposure.
8.2 Ecological Risks
The ecological risk assessment evaluated potential exposures offish, birds, mallard ducks.
frogs, and pocket gophers to smelter related chemicals of concern within likely habitat areas.
Potential risks to ecological receptors were estimated by calculating Hazard Quotients (HQs) and
Hazard Indices (His). The HQ is the ratio of environmental concentration or dose to a safe level
or dose. If the HQ for a chemical is equal to or less than 1, it is assumed that there is no
appreciable risk that adverse health effects will occur. If an HQ exceeds 1, there is some
possibility that adverse effects may occur, although an HQ above 1 does not indicate an effect will
definitely occur. However, the larger the HQ value, the more likely it is that an adverse effect
may occur.
Hazard quotients for each contaminant at each location and by each pathway were
summed to obtain a Hazard Index (HI) for each receptor. Figures 14 to 17 summarize the His
for the belted kingfisher, killdeer. valiey gopher, and the mallard. The assessment considered
exposure via. ingestior. of water, sediment, soil, and food within the ecological 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 HI is apr:opriate to consider
when determining risks to individual ecological receptors. Tne LOAEL KI best characterizes
risks to populations. Figures for the kingfisher and mallard also illustrate an adjustment with
"area use factors" as their' home ranges are larger than the actual Site areas. All figures illustrate
risk up gradient of the Site. on-Site, down gradient of the Site, and in the depressions (wetlands).
Lead concentrations in soils and sediments as well as selenium concentrations in plants are the
largest contributors to risk to ecological receptors at the Site.
Hazard quotients for trout and frogs were calculated by comparing exposure point
concentrations for surface water with toxicity reference values. The evaluation, documented in
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the ecological risk assessment, shows essentially no risks to brown trout or frogs in Little
Cortonwood Creek.
8.2.1 Discussion of Results
The estimate of relative risk is the risk estimate on-Site divided by the risk estimate up
gradient. It is a useful measure of how much higher the risk is due to the Site relative to inherent
risks. The estimate of absolute risk is the HQ or the HI for each location. As can be seen in
Figures 14-17, in general, 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
estimates are considered by EPA when determining if remedial action is warranted. There are
essentially no risks to aquatic life in Little Cortonwood Creek considering both relative and
absolute risk estimates. The greatest areas of concern at the Site are the wetlands, where both
absolute and relative risk estimates are high.
Interpretation of these risk estimates must take into account the following sources of
uncertainty in the calculations:
1. Where measured concentration data were not available, literature based
bioaccumulation factors were applied to estimate concentrations. This use of predicted
rather than measured data adds to the uncertainty in the assessment. This uncertainty may
be significant for the risks predicted for the mallard and the pocket gopher, since predicted
excess risk is associated with ingestion of contaminants in vegetation. These plant
concentrations driving the risk were predicted using literature based bioaccumulation
factors. Without true site measurements, it is difficult to ascertain if this risk is
representative.
2. Sample preparation may also lead to some degree of uncertainty. Benthic macro
invertebrates which were collected at this Site were not rinsed prior to analysis. This
couic lead to a earn- over of sediments thereby 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 .ollected from
this Site to support the ecological risk assessment may have contributed to artificially high
rnetai concentrations, thereby elevating risk estimates.
3. The risks were calculated on the assumption that the receptor spent 100% of its time
within a location. Depending on the home range and actual use of each location, the
actual risks could be lower.
Observations of the ecological receptors at the Site in the form of qualitative surveys
documented ir. the ecological risk assessment suggest that the predicted effects are not occurring.
EPA believes that runner biomoriitoring is needed to validate this assumption. Attempts to
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reduce the risi:s through active measures such as removing and replacing sediments in the
wetlands will likely result in loss of the habitat. In EPA's judgement, the wetlands are of great
ecological interest and loss of this habitat may have a more negative impact on the local
ecosystem than the highly uncertain predicted risks.
Also relevant to the discussion of ecological risks is the fact that current Site development
plans include extensive regrading which will likely result in filling of the wetlands. The Corps of
Engineers has jurisdiction over the wetlands if affected by development actions and may or may
not allow the filling of these wetlands. If it were to occur, the filling of the wetlands would be an
ecological impact in itself but would essentially break the exposure pathways of concern for
ecological receptors.
8.3 Remedial Action Objectives
The baseline risk assessment provides the basis for EPA's decision that actual or
threatened releases of hazardous substances at the Site may present an imminent and substantial
endangerment to public health, welfare, or the environment. Specifically, unacceptable risks were
identified for the following exposed populations via the ingesn'on of arsenic and lead in dust and
soil and the ingestion of arsenic in ground water
Current and Future NCI Workers
Current CI Workers
Current and Future Residents
EPA has determined that remedial action is warranted at this Site. Remedial Action
Objectives fRAOs) were developed by EPA for the exposure pathways and contaminants of
concern associated with unacceptable risks under the current and reasonably anticipated future
land use. These RAOs are presented in this section.
8.3.1 Overarching RAO
Development of the on-faciiity portion of the Site 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 commitment to help
communities revitalize properties where expansion or redevelopment is complicated by real or
perceived environmental contamination, to mitigate potential health risks, and to restore economic
vitality. Based on consideration of Brownfieids goals, 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 emironmental
contamination.
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EPA developed media-specinc RAOs using the basic assumption that the reasonably anticipated
future land use will be commercial/light industrial use of the on-faciiiry area and residential use of
the off-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 all of which is summarized in Section 3.1. This information supports EPA's
conclusion that the current industrial and residential use of the on-faciiity property wilj end in the
very near future.
8.3.2 Chemical Specific Applicable or Relevant and Appropriate Requirements (ARARs)
In accordance with the National Contingency Plan (NCP), remediation levels are a subset
of the RAOs and consist of medium-specific chemical concentrations that are protective of human
health and the environment. These remediation levels are based on risk assessment or ARARs.
Table 16 presents the chemical specific ARARs for the Site which are incorporated into the
RAOs as remediation levels to address specific contaminants and exposure pathways. Appendix
B presents the derivation of the risk based remediation levels for sci; which are also incorporated
into the RAOs. Appendix C presents the technical support for EPA's selection of the
remediation level for arsenic in shallow ground water.
8.3.3 On-Facilhy SoQs/Smeher Materials
RAOs: Prevent unacceptable risks to current and future workers or to ecological
receptors due to the ingestion of soil/smelter materials containing arsenic
or lead.
Reduce the uncertainties in the predicted risks to ecological receptors
Remediation Levels:
The remediation levels for soils/smelter materials are risk-based.
For workers, prevent exposure to soiis-'smelter materials containing levels
of arsenic or lead which would pose a potential excess cancer risk greater
than 1E-4: a potential chronic health risk defined by a hazard quotient of
one; or resul; in a greater than 5% chance that the fetus of a pregnant
worker would have a blood lead level greater than 10 micrograms per
deciliter (ug/dL). Based or. the findings of the Baseune Human Health
Risk Assessment and a reasonably anticipated future land use that is
commercial/light industrial, these levels correspond to:
Surface soils shai! not exceed 1.200 milligrams per kilogram
(me/kg) arsenic as the 95°/o upper confidence limit on the arithmetic
mean within any given exposure unit.
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Surface soils shall not exceed 5,600 me/kg lead as the arithmetic
mean within any given exposure unit.
8.3.4 On-Faciiity Groundwaler
RAOs- Minimize future transport of arsenic from source materials to the shallow
aquifer.
Prevent exposure of human and ecological receptors to ground water with
arsenic concentrations that represent an unacceptable risk.
Prevent unacceptable increases in the arsenic concentrations of the
intermediate aquifer resulting from arsenic migration from the shallow
aquifer.
Remediation levels:
The remediation levels for ground water are based on ground water ARARs.
Meet the MCL (0.05 milligrams per Liter (mg/L)) for dissolved arsenic in
shallow groundwater at the east and west Site boundaries.
Meet the MCL (0.05 mg/L) for dissolved arsenic in the intermediate
aquifer.
Meet the Alternate Concentration Limit (ACL) of 5.0 mg/L for dissolved
arsenic within the unconnned shallow aquifer v.itnin the Site boundaries.
The compliance points for the ACL in shallow ground water are in the
vicinity of ground water discharge locations south of Little Cottonwood
Creek.
8.3.5 Little Cottonwood Creek Surface Water
RAOs: Protect Little Cottonwood Creek water quality by preventing unacceptable
increases of arsenic concentrations in surface water resulting from ground
water discharges or surface water run-off from the Site.
Remediation Levels:
The remediation levels for surface water are based on surface water ARARs.
Meet the Utah Standards of Quality for Waters of the State for trivaient
arsenic of 190 micrograms per liter (ug/L) as a 4 day average and 360 ug/L
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as a 1 hour average in Little Cottonwood Creek.
Meet the Utah Standard of Quality for Waters of the State for dissolved
arsenic of 100 ug/L in Little Cottonwood Creek.
8.3.6 Off-Facility Soils
RAOs Prevent unacceptable risks to current and future residents due to the
ingestion of soil containing lead.
Prevent unacceptable risks to current and future NCI workers due to the
ingestion of soil containing lead.
Remediation Levels:
The remediation levels for off-facility soils are risk based.
The concentration of lead in surface soils within residential areas of the Site
shall not exceed 1200 mg/kg as an arithmetic mean within any given
residential yard. EPA developed a range of 630 mg/kg-1260 mg/kg for the
remediation level for soils in residential areas. Appendix B provides the
details of the development of this range. The April 23, 1997 risk
management strategy prepared by EPA provides the rationale for EPA's
selection of 1200 mg/kg as the appropriate remediation level for the
residential areas of this Site. The specific factors considered in making this
determination for each property were the current land use. the reasonably
anticipated land use. the likelihood of exposure to soil (measured
qualitatively by ground cover), and empirical evidence of exposure to lead.
The concentration of lead in surface soils within commercial areas of the
Site shall not exceed 5600 mg/kg as an arithmetic mean within any given
commercial property.
8.3.7 On-Facility Ecological Study Areas
RAO Reduce uncertainties in predicted risks to ecological receptors
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9.0 COMPARATIVE ANALYSIS
This section presents a summary of the comparative analysis of the remedial alternatives
developed for the Site to achieve the RAOs. This two-stage analysis reviews the remedial
alternatives in relation to the threshold criteria and primary balancing criteria specified in the
National Contingency Plan (NCP). Modifying criteria are then discussed in Section 9.2. The
findings of the comparative analysis are summarized in Section 9.3, including selection of a
comprehensive remedy for the entire Site.
9.1 Identification of Alternatives
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 Site
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
Characterization Report and the Baseline Risk Assessment :
Category I and II: Category I and n 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 classified as Category I or EL Alternatives
were developed for Category I and n 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 Et
material must achieve the remediation levels established for ground water.
Category I: 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 within the on-faciiiry
area. The identification of Category I materials considers :
A. Associated with distinctly elevated arsenic concentrations in underlying
shallow ground water (greater than or equal to 15 mg/L);
B. High arsenic concentrations compared to other categories of materials
on Site,
C. Visual characteristics (e.g., color, panicle size) which indicate arsenic
trioxide;
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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. Located where former smelter structures which processed or stored
arsenic trioxjde were historically located. Category I materials are located
in the areas of the 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 design considering the results of
sampling material deeper or adjacent to this material.
Category II: Low level threat ground water source material characterized as large volumes of
diluted arsenic tnoxide or flue dust often mixed with soil, new fill, or debris from
former smelter flues. These materials have lower arsenic concentrations than
Category I materials and are potentially a significant source of ground water
contamination. There is an estimated quantity of 68.000 cubic yards of Category
n material within the on-facility area. The identification of Category n materials
considers:
A. Located near or within the footprint of former smelter structures such
as the concrete flues, the roasting plant, the baghouse, storage areas.
transport areas, and the blast furnace area. The exact limits of Category n
material \\iii be denned in remedial design considering the results of
sampling material deeper or adjacent to this material;
3. Visual characteristics (e.g., color, panicle size) which indicate flue dust
or diluted arsenic trioxide: and
C. Potentiai current or future threat to ground water quality. Category n
material is associated with arsenic in shallow ground water above the ACL.
Category HI: Category m materials are surface soils which are predicted ;o pose an
unacceptable risk to NCI workers within the on-faciiity area. Alternatives for
Category m materials must achieve the remediation levels for on-faciiity
soils'smelter materials. Material in this category will not pose a threat to ground
water. The identification of Category HI materials considers:
A. Located within on-faciiity EUs identified as causing unacceptable health
risks to XCI workers ("EU-3 and EU-4):
3. Lead concentrations greater than 5600 mg''kg as the arithmetic mean
within the EU: and
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C. Arsenic concentrations greater than 1200 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 materials. The key
components of each alternative considered in the comparative analysis are summarized below.
Alternative 1 - No Action
• The Murray Smelter Site would be left in its current condition.
Alternative 2 - Excavation & Onshe Consolidation/Barrier Placement/Monitored Natural
Attenuation/Institutional Controls/Removal and Disposal of Off- Facility Soils
• Source control via excavation of Category I and II materials and consolidation in
separate repositories in the on-faciiiry area.
Monitored natural attenuation of shallow ground water within and down gradient
of source areas to achieve the ACL. The mechanism of attenuation of arsenic in
shallow ground water is adsorption to the iron oxides in the subsurface soil.
Surface water monitoring in Little Cottonwood Creek and monitoring of the on-
Site ecological study area. Monitoring of wetlands will include surface water,
sediment and benthic macro invertebrates. Monitoring of terrestrial areas will
include plants and soil.
Institutional controls in the form of a Murray City ordinance establishing an
"overlay district" which includes zoning to prevent residential and contact
intensive industrial uses within the former smelter operational areas, prohibitions
on the development or use of any ground water wells within Site boundaries
except for EPA approved monitoring wells, maintenance of the barriers, and
controls or. excavated subsurface material within the former smelter operational
areas. Other institutional controls include restrictive easements that run with the
land which contain the same land use and ground water well construction
restrictions.
Covering of Category D3 materials in place with barriers sufficient to prevent
direct contact. Such barriers may be pavement, landscaping, soil caps, or
sidewalks.
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Soil removal/replacement with clean soil, or other fill in off-facility residential or
commercial properties with lead concentrations in soils that may represent an
unacceptable risk . Excavated soil will be used in the on-facility area of the Site as
subgrade material during development or road construction.
Alternative 3 - Excavation/Onshe Consolidation^!: OflEsite Disposal/Monitored Natural
Attenuation/Barrier Placement/Institutional Controls/Removal and Disposal of Off-Facility Soils
• The same actions as Alternative 2, except Category I materials are excavated and
disposed offsite.
Alternative 4 - Excavation/Onshe Consolidation& Ofishe Disposal/Barrier Placeman/Institutional
Controls/Ground Water Extraction/Removal and Disposal of Off-Facility Soils
All Alternative 3 components.
Ground water extraction in areas of highest arsenic concentrations, treatment of
extracted ground water, and discharge to the sanitary sewer system.
Alternative 5 - Excavation/Onsite Consolidation& Offshe Disposal/Barrier Placement/Institutional
Controls/In-Shu Ground Water Treatment/Removal and Disposal of Off-Facility Soils
All Alternative 3 components.
Option A - Constructed wetlands to treat shallow ground water prior to discharge
to Little Cottonwood Creek.
Option B - Permeable barrier treatment wall to treat shallow ground water prior to
discharge to Little Cottonwood Creek.
Alternative 6 - Excavation/Onshe Consolidation & Off She Disposal/Monitored Natural
Attenuation/Barrier Placement/Institutional Controls/Off- Facility Community Heahh Education,
Monitoring and In.rrvention
• .All Alternative 3 components for the on-faciiiry area.
• Community health education and monitoring for residents 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 risk is indicated by the monitoring program.
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Alternative 7 - Excavation/Onsite Consolidation & OSsrte Disposal/Monitored Natural
Attenuation/Barrier Placement/Institutional Controls/Soil Tilling in Off-facility Areas
• All Alternative 3 components for the on-facility area
• Deep tilling in off-facility residential or commercial properties with lead
concentrations in soils that may represent an unacceptable risk. Institutional
controls to protect the integrity of soil barriers and to place requirements
on the handling and disposal of any excavated material from beneath the
tilled zone if the concentrations in this material are above a level of
concern.
9.1.1 Threshold Criteria Analysis
9.1.1.1 Overall Protection of Human
As demonstrated in the Baseline Risk Assessment, Alternative 1, No Action does not meet
the threshold criteria of overall protection of human health and the environment except that no
action is appropriate for slag since no unacceptable risks associated with exposure to slag were
identified by EPA in the Baseline Risk .Assessment. With the exception of Alternative 1, all
alternatives considered in the comparative analysis meet the requirements of the RAOs and
provide overall protection of human health and the environment. Differences in overall protection
are related to the level of certainty with regard to actions for Category I materials and relative
effectiveness of actions on ground water and the off-facility soils. There are also differences with
respect to the key overarching RAO requiring that remedial actions be consistent with the current
and proposed land use.
Source control via excavation and consolidation of Category I and n materials in separate
repositories (.Alternative 2) would prevent future infiltration of surface water, thus protecting
ground water from further impact due to transport of arsenic from this source material.
Excavation'onsite consolidation is an effective method of source control at this Site primarily due
to the ease in locating the source material. The material is generally within the locations of
historical smelter structures. Fo. example, the results of sampling subsurface soils to a depth off
feet in the vicinity of the baghc-us* show that excavation of the upper 2 feet of material from
within the footprint of the former baghouse would remove approximately 97 percent of the
arsenic present in this source area. (This calculation was done by dividing the mass of arsenic in 2
fee: by the total mass of arsenic measured in 5 feet of subsurface soil at the location of the highest
arsenic levels.)'
Barrier placement over Category EH materials is a component of all alternatives except
.Alternative 1 and would be effective in preventing direct exposure as long as barriers are
maintained The institutional controls which include public and private land use restrictions and a
ban on construction of ground water wells (with the exception of EPA approved monitoring
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wells) within the on-facility area will prevent Site uses which could result in unacceptable risks
due to residential or contact intensive use or ground water ingestion. In the off-facility area, soils
containing lead exceeding remediation levels would be excavated to at least 18 inches and the
excavated soil brought onto the on-facility area for incorporation into remedial actions or
development. The off-facility excavated areas would be replaced with soil or other clean fill.
Removal of soil with lead concentrations above remediation levels provides protection of human
health and the environment by breaking the exposure pathway of direct contact with contaminated
source material.
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) actions provide essentially the same level of overall protection, removal of Category I
materials from the Site would eliminate completely any long-term concerns regarding the potential
for direct exposure (the levels of arsenic in Category I materials may cause acute health effects)
and the potential for the materials to act as sources of arsenic to ground water in the future
(arsenic in Category I materials is predominantly the soluble oxide and sulfate forms) in the event
that the repository was damaged resulting in a release of these materials into the environment.
Although not likely to occur, the possibility of its occurrence illustrates the difference between the
two alternatives.
Alternative 4 contains the same components as Alternative 3 and adds a ground water
extraction system. She specific hydrologic and chemical factors limit arsenic transport rates to the
extraction wells and thus limit the rate at which arsenic may be removed from the aquifer. Long
term pumping rates are limited by the flux or supply of ground water introduced to the aquifer.
Section 4 of Appendix A of the Feasibility Study contains a conceptual design for a ground water
extraction system and approximate time frames are predicted for arsenic extraction rates. The
analysis demonstrates that the flux of water through targeted portions of the aquifer will not
change as a result of installing a pumping system. Therefore, addition of an extraction system
within the source areas will not accelerate the rates of decline in arsenic concentrations in ground
water relative to the rates achieved through source control and natural attenuation. The time
frame required to meet remediation levels in ground water within the source areas is predicted to
be between 100-125 years with the insxallation of a ground water extraction system. Monitored
natural attenuation is predicted to require approximately 100-150 years to achieve remediation
levels throughout the She . For bo*h source control with monitored natural attenuation and
source control with ground water extraction, the same set of site specific factors limits the rate at
which 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 wells
necessary.
Alternative 5 contains the same components of Alternative 3 and adds in-situ treatment of
shallow ground water (either by constructed wetlands or by a permeable barrier treatment wall)
near Little Cottonwood Creek. Currently ground water discharges to Little Cottonwood Creek.
However, the principal areas of elevated arsenic concentrations in ground water are distant from
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the creek and are not predicted to intercept the creek for over 100 years. Due to source control
and attenuation within the aquifer, arsenic concentrations are expected to be significantly lower by
the time arsenic from these areas intercepts the creek. The types of treatment systems included in
Alternative 5 are not expected to be effective for periods greater than 10 years without extensive
routine maintenance. Implementation of either treatment option will have limited short-term
effectiveness due to the diffuse source areas which may include ground water from both sides of
the creek and surface water runoff and complex ground water flow patterns near the creek and
may provide no benefit for long-term effectiveness in reducing arsenic transport to Little
Cottonwood Creek. Therefore, implementation of in-situ ground water treatment systems is not
expected to provide additional performance over the source control and monitoring actions
included in Alternative 3.
Alternatives 6 and 7 include two different options for addressing the off-facility soils
containing unacceptable concentrations of lead. Alternative 6 includes community education to
inform residents on methods to prevent unacceptable exposures and a voluntary blood-lead
monitoring program. If the monitoring program indicates the potential for unacceptable risk,
intervention actions would be implemented. These actions would be designed on a case-by-case
basis and could include surface control such as vegetation of bare areas, barrier placement or soil
removals. This alternative is expected to be protective of human health if participation in the
program is sufficiently high. Alternative 7, soil tilling, is also expected to be protective of human
health and the environment. In the majority of off-facility areas of concern, lead concentrations
are elevated at the surface. The source of this lead is likely due to deposition of emissions from
the smelter during its period of operation. In these cases, deep tilling will reduce lead
concentrations to below levels of concern. Site characterization data indicate that at some
locations lead concentrations are above a level of concern over the entire tilling zone, possibly due
to the placement of slag. In these areas, lead concentrations in surface soils would not 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 Applicable or Relevant and Appropriate Requirements
9.1.2.1 Ground Water ARARs
Chemical specific ARARs are identified in TaMe 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 those otherwise applicable under the
following conditions stated in 55 Federal Register 8732:
The ground water must have a known or projected point of entry to surface water with no
statistically significant increase in contaminant concentration in the surface water from
ground water at the point of entry, or at any point where there is reason to believe
accumulation of constituents may occur downstream. In addition, the remedial action
must include enforceable measures that will preclude human exposure to the contaminated
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ground water at any point between the facility boundary and all known and projected
points of entry of such ground water into surface water.
Quarterly monitoring of surface water and ground water at the Site has demonstrated that
ground water from the shallow aquifer discharges to Little Cottonwood Creek at locations along
the northern Site boundary. The contaminant of concern in ground water is arsenic. Information
collected since April, 1997 and documented in quarterly monitoring reports indicates the primary
source of arsenic to Little Cottonwood Creek exists at a point discharge at the eastern facility
boundary. Loading calculations indicate that 88%-100% of the arsenic loading to Little
Cottonwood Creek is due to this point discharge, not to the ground water discharge from the
Site. EPA has determined that the conditions at Murray Smelter satisfy the requirements of
CERCLA 122 (d)(2)(B)(ii) which allow the establishment of an ACL for groundwater. EPA has
established 5.0 mg/L as the ACL for dissolved arsenic in ground water. Appendix C provides a
summary of the calculations used by EPA to determine a range of acceptable ACLs. In making its
determination, EPA considered the zone of potential shallow ground water discharge from the
Site and conservatively assumed all discharge is from the Site or south side of the creek. EPA
also based its determination on low flow conditions in Little Cottonwood Creek and Site specific
hydraulic conductivity and hydraulic gradient measurements. The ACL of 5.0 mg/L for dissolved
arsenic is a ground water concentration which will assure that Little Cottonwood Creek is
protected at its beneficial use, agricultural use, given the discharge of shallow ground water to the
creek.
In accordance with the NCP, the situation at Murray Smelter fulfills the CERCLA
statutory criteria for ACLs, including the analysis in the Feasibility Study which demonstrates that
active restoration of the groundwater to MCLs is not practicable. The existing documentation of
these conditions precludes the need for an ARAR waiver. The remediation level for dissolved
arsenic in shallow ground water within the Site boundaries is the ACL of 5.0 mg/L. Achieving
this level will constitute compliance with the groundwater ARARs. The MCL is currently met at
the on-facility area boundaries (the north boundary is north of the ground water-surface water
mixing zone north of Little Cottonwood Creek).
Source control actions contained in Alternatives 2 through 5 are expected to minimize
transport of arsenic from smelter materials and result in improvement of ground water quality
such that the ACL will be met within the entire on-facility area in a time frame of 100-150 years.
This approach is reasonable given 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 additional action of ground water extraction contained in Alternative
4 would not result in a significant decrease in the time required to meet the ACL or a reduction in
arsenic loading to the creek. Time frames for achieving the ACL in Alternative 4 are estimated to
be 100 - 125 years. There are fundamental technical limitations for the effective performance of
an extraction system related to the low aquifer yield and high partitioning of arsenic to aquifer
solids. The additional action of an in-situ treatment contained in Alternative 5 would not
contribute to reduction of current arsenic concentrations in the shallow aquifer and would have a
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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 not predicted to
intercept the creek for at least 100 years. Attenuation by adsorption is expected to significantly
reduce the arsenic concentrations from these areas by the time they reach the creek.
The ACL is currently achieved at monitoring well MW-112, the well location closest to
compliance points near Little Cottonwood Creek which will be established as part of the remedy.
Within 30-40 years, the effects of the source control actions of Alternative 3 along with the
monitoring activities are expected to demonstrate 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. EPA expects the remaining areas of the shallow aquifer to achieve
the ACL within a time frame of 100-150 years.
Although not identified as a contaminant of concern, selenium has been detected in the
shallow ground water within the Site boundaries at levels exceeding the MCL of 0.05 mg/L.
These detections are at 8 well locations within the on-facility area. However, the MCL for
selenium has consistently been met at well locations just south of Little Cottonwood Creek and
the east and west on-facility boundaries (well locations MW-112, MW-109, MW-102, and MW-
104 on Figure 6). The preamble to the NCP states at 55 Federal Register 8753 :
"...there may be certain circumstances where a plume of ground water contamination is
caused by releases from several distinct sources that are in close geographical proximity."
In cases such as these, the NCP preamble suggests that
"...the most feasible and effective 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."
EPA considered this discussion, the proximity of the sources of arsenic and selenium (both
within the former smelter operational area), as well as the reliability of the restrictions on ground
water use within the Site boundaries in establishing the points of compliance for the selenium
MCL at the well locations just south of Little Cottonwood Creek. The yound water ARAR for
selenium is currently met at the points of compliance. Selenium will be included as part of the
ground water monitoring component of the remedy.
9.1.2.2 Surface Water ARARs
State of Utah Water Quality Standards are identified as applicable in Table 16. The data
gathered during the site characterization effort and subsequent sampling events indicate that
Utah's aquatic life standard for arsenic (0.19 mg/L arsenic as As (Til]) is consistently being met,
but that the arsenic standard for agricultural use (dissolved arsenic of 0.1 mg/L) is not being met
during low-flow conditions within the on-facility boundaries. The standards for both uses were
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met at location SW-6, in Little Cottonwood Creek downstream of the Site during the site
characterization sampling events.
The source control actions will address the Murray Smelter-related 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
Dell's trailer court. The control of this discharge and the natural attenuation of shallow ground
water to the level of the ACL is expected 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 will protect Little
Cottonwood Creek in the future.
Little Cottonwood Creek does not currently meet the beneficial use for agriculture due to
high levels of TDS from urban runoff and high phosphorus. Neither TDS nor phosphorus are
related to the Site. An investigation of the actual use of Little Cottonwood Creek was conducted
in April, 1997. Two diversions of surface water were observed up gradient of the Site, neither of
which was for agricultural use purposes. No diversions were observed down gradient of the Site.
This information suggests that the current uses of Little Cottonwood Creek are not consistent
with the beneficial use. EPA believes that a 3 year period for achieving the agricultural use
standard for dissolved arsenic in Little Cottonwood Creek is reasonable in this case.
9.1.2.3 Action- and Location- Specific ARARs
Tables 17 and 18 present the action specific and location specific ARARs for the Site. All
alternatives will meet these ARARs. On-facility alternatives which include consolidation of
source materials within the Site boundaries do not trigger the land disposal restrictions, therefore
these requirements are not applicable. The Site boundaries are considered by EPA to be an "Area
of Contamination" as defined in the NCP. Movement of waste within an Area of Contamination
does not constitute placement.
9.1.3 Primary Balancing Criteria
9.1.3.1 Short-Term Effectiveness
As discussed above, all alternatives with the exception of Alternative 1, No Action, meet
the requirements of the RAOs and provide overall protection of human health and the
environment. There are no substantial differences between alternatives 2,3,4,and 5 in terms of
short-term effectiveness. Each alternative entails excavation and handling of Category I and II
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 the presence of heavy
construction equipment on the Site would be similar with respect to each alternative as well as to
the potential risks posed by current industrial uses. Response objectives would be met at the
same time for all alternatives once excavated materials are disposed and barriers installed.
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Alternative 6 contains community health education and monitoring for the off-facility area.
This alternative provides a high level of short term effectiveness. Although there are potential
uncertainties associated with the willingness of residents to participate, the high level of
involvement by Murray City and the high level of community awareness concerning the Site
suggest that the program will be effective in the short term. Alternative 7, tilling in the off-facility
areas, may not be as effective as soil removal in breaking the exposure pathway due to the
presence of lead below the tilling zone.
9.1.3.2 Long-Term Effecliveuess and Perm»"ence
A primary consideration in the evaluation of long-term effectiveness is that a major
portion of the on-facility area is expected to be redeveloped in the near future. The expected land
use of office/light commercial will reduce the potential for unacceptable risks ("contact intensive"
activities would end), and integration of remedial actions with redevelopment, the key overarching
RAO, would allow for optimizing the management of smelter materials remaining at the Site such
that confidence would be increased that the remedy and subsequent institutional
controls/monitoring will be effective over the long term.
Alternatives 2 and 3 differ in terms of actions on Category I materials. Under Alternative
2, Category I materials would be excavated and consolidated in a repository in the on-facility
area. Under Alternative 3, Category I materials would be excavated and disposed of off-site.
Given the current and reasonably anticipated future land use and the opportunity to install a
repository in a suitable location under the control of Murray City, both actions would provide
long-term protection of human health and the environment. Removal of Category I materials
from the Site would completely eliminate any future concerns regarding the potential for direct
exposure or contact of Category I materials with infiltrating ground water and therefore provide a
higher level of performance in terms of long-term effectiveness. For Category n materials,
consolidation into a repository would provide long term protection of human health and the
environment. Category n materials may be low-level sources of arsenic to ground water under
ambient infiltration conditions. Minimizing the potential for infiltration of surface water through
these materials by consolidation beneath a low-permeability barrier with surface control is
expected to be effective in preventing migration of arsenic to ground water. This same action is
included in Alternatives 2, 3, 4 and 5. Control on the use of land and ground water, the secor.d
component of the institutional controls, will be effective in preventing direct contact with
unacceptably high levels of arsenic and lead in soil and ground water and will prevent the
migration of arsenic from the shallow aquifer to the intermediate aquifer. These controls will be
implemented through city zoning and restrictive easements which run with the land. Thus they
will be effective in the long term and are considered permanent restrictions.
Alternatives 3, 4 and 5 contain the same actions on smelter materials and provide the same
basic level of long-term effectiveness. Alternatives 4 and 5 include additional actions to contain
the extent of arsenic transport. Alternative 4 contains a ground water extraction system in the
areas of highest arsenic concentrations in the shallow ground water. The additional action of
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ground water extraction would eventually provide for reductions in arsenic concentrations in
shallow ground water and would be effective for long-term containment of arsenic already present
in the shallow aquifer near the former baghouse and thaw house areas. However, modeling
indicates that an extensive ground water extraction system would not substantially reduce the time
required to achieve the RAOs for the shallow aquifer and Little Cottonwood Creek. Overall,
Alternative 4 provides lower performance than Alternative 3 with respect to long-term
effectiveness because it would not provide a significant improvement in environmental conditions
relative to Alternative 3 and would entail a high level of operation and maintenance.
Alternative 5 includes in-situ treatment of shallow ground water in the vicinity of Little
Cottonwood Creek with the purpose of limiting arsenic transport and discharge to the creek.
Groundwater monitoring indicates that the two principal areas of ground water contamination do
not currently extend to Little Cottonwood Creek and are not predicted to do so for more than
100 years. Source control actions and natural attenuation of arsenic in the aquifer are expected to
significantly reduce the arsenic concentration by this time. The long-term performance of systems
such as constructed wetlands and permeable barrier treatment walls to treat arsenic is limited.
Effective removal is only expected for a period of approximately 10 years due to the mildly-
oxidizing ground water chemistry. Therefore, if these types of systems were installed in the near
future, they would not be effective at the time when arsenic from the principal source areas
reaches them.
In the off-facility area, lead concentrations in residential soils range up to 1,800 mg/Kg.
The remediation level lead in soil in the off-facility area is 1,200 ppm. Alternative 6, which
includes community education to provide information on methods to prevent unacceptable
exposure, is expected to provide long-term protection of human health through the
education/monitoring components with additional assurance due to the option for intervention
measures in the future if the potential for unacceptable exposures is indicated.
For Alternative 7, because lead 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 level of concern. In this case, Alternative 7 would rely on similar community education
measures described under Alternative 6. Therefore, Alternatives 6 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 level of long-
term protection because surface soils with lead concentrations above a level of concern would be
excavated and replaced with clean soil or other fill. If complete removals are achieved, this action
would provide the highest level of long-term effectiveness because all soils of concern would be
removed.
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9.1.3.3 Reduction of Toxicrtv. Mobility and Volume Through Treatment
With the exception of the no action alternative, the alternatives considered by EPA do not
provide significantly different performances in terms of reduction of toxicity, mobility and volume
of arsenic or lead through treatment.
Alternatives 2 and 3 do not contain any treatment components except the possible
treatment of Category I material before disposal at an off-site facility. For Alternative 2, a
reduction in the mobility of arsenic in subsurface soils would be expected due to the minimization
of infiltration through Category I and n materials. For Alternatives 3, 4 and 5 a similar reduction
would be expected due to removal of Category I materials and minimization of infiltration through
Category n materials.
Alternative 4 contains a treatment component; treatment of extracted ground water to
remove arsenic prior to discharge to the sanitary sewer. This treatment component would
provide little if any reduction in toxicity, mobility or volume of arsenic at the Site in comparison
to Alternatives 2 and 3. However, the ground water extraction system would provide some
additional reduction in mobility of arsenic in the shallow aquifer relative to Alternatives 2 and 3
due to physical containment 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 provide any reduction in toxicity or volume of arsenic at the
Site. It would provide a minor reduction in the mobility of arsenic in shallow ground water near
Little Cottonwood Creek. As discussed above, the principal areas of ground water contamination
are distant from the creek and arsenic from these areas is not predicted to intercept the creek for
over 100 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 expected to operate efficiently for only 10 years without continued routine
maintenance and would, therefore, not be effective for the time frame of principal interest.
Overall, therefore there are no substantial differences in performance of the alternatives
against this criterion. Alternatives 2, 3 and 5 perform at essentially the same level, whereas
Alternative 4 performs at a slightly higher level due to physical containment of arsenic in shallow
ground water.
For the off-facility area, lead is immobile in Site soils and lead concentrations in the off-
facility area are well below levels which would warrant treatment. Treatment is therefore not
applicable to off-facility soils.
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9.1.3.4 Implemeptabflity
The source control activities contained in Alternatives 2, 3, 4 and 5 are implementable
either for current land use or for the expected future land use. Excavation of Category I and n
materials would be implementable with some minor disruptions to current industrial activities.
Physically suitable repository locations for Category I and n materials are also available for
current or future land use. Off-site disposal of Category I materials (a component of Alternatives
3, 4 and 5) would also be readily implementable. In addition, barrier placement over Category ffl
materials would be implementable with minor disruption to current industrial/commercial
activities, or could be implemented during redevelopment of the area. Institutional controls to
protect barriers are implementable given the high degree of involvement of the current land
owners and Murray City.
Alternatives 4 and 5 contain the same source control actions as Alternative 3 with the
addition of two types of remedial action alternatives on ground water. The extraction system
contained in Alternative 4 would be difficult to implement due to the low yield of the aquifer and
high partitioning of arsenic to the aquifer 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, including a treatment plant would be difficult and would not be compatible with
future land use. Alternative 4 therefore has a lower performance than Alternatives 2 and 3 in
terms of implememability. Ether of the options evaluated for in-situ ground water treatment
under Alternative 5 (wetlands or treatment wall) would have numerous technical difficulties
associated with effective implementation and operation. Considerations include the limited area
available (for wetlands), depth and complex flow patterns of ground water in the vicinity of the
creek, the presence of the units in the flood plain, and uncertainties associated with the
effectiveness of the technologies in removing arsenic. In addition, the technologies would require
a high level of long-term maintenance. For the ground water conditions found at the site,
effective performance of the types of technologies under consideration is approximately 10 years
without on-going maintenance. Replacement of substrate in a wetlands or of ferric sulfate in a
treatment wall may be required at approximately 10-year intervals. This action would not be
compatible with the future land use and Alternative 5 has a lower performance than Alternative 3
in terms of implementability.
In the off-facility area, community health education and monitoring programs contained in
Alternative 6 would be readily implemented because only non-engineering controls are
considered. Excavation and soil replacement evaluated under Alternatives 2-5 are also expected
to be readily implemented. Residents in the areas of concern have participated in the site
characterization study, and there is a high level of awareness concerning the Site in the general
community. These types of actions have been performed at several sites around the country.
Alternative 7, which requires soil tilling rather than excavation at the same locations, would be
more difficult to implement than the other alternatives. This is primarily due to technical
difficulties of tilling in small spaces such as residential yards, where structures and plants would
make some areas difficult to access.
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9.1.3.5
Cost Analysis
Details of the cost analysis are contained in the final Feasibility Study. The costs estimated for the
on-facility area are shown in Table 19.
Table 19
Item
Capital Cost
Annual O&M
Present Net
Worth
Alternative
2
$8.7
$0.14
$10.1
Alternative
3
$8.9
$0.14
$10.3
Alternative
4
$10.8
$0.27
$14.3
Alternative
Sa
$10.6
$0.21
$13.4
Alternative 5b
$21.9
$0.23
$40.2
O&M costs are estimated for 30 years. The extraction component of Alternative 4 and in-
situ treatment components of Alternative 5 would require O&M for over 100 years and so would
entail substantially higher costs than shown above.
The cost to implement Alternatives 2 and 3 is considered to be low; the costs to
implement Alternative 4 and 5 a 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 Table 20.
Table 20
Item
Capital Cost
Annual O&M
Present Net
Worth
Alternative
6
$0.57
$0.05
$1.34
Alternative
7
$0.64
$0.015
$0.93
Alternative
2-5
$1.1
$0.013
$1.33
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9.2 Modifying Criteria
9.2.1 State Acceptance
The Utah Department of Environmental Quality (UDEQ) was provided the opportunity to
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 meetings. In comments on the Proposed Plan, UDEQ indicates agreement that
Alternative 3 is the most reasonable choice for the Site. However, UDEQ indicated that this
agreement was not based on the length of time or the current levels of contamination. Given the
"extremely long" time frames and uncertainty involved in ground water restoration under any
alternative, UDEQ has determined that it is technically impracticable within a reasonable time
frame to meet ARARs at this Site, and has agreed on that basis and for other reasons given in this
ROD (e.g., protection of human health and the environment) that the remedy described in this
ROD is appropriate. While EPA characterizes the situation differently, both parties are in
agreement about the ultimate approach. UDEQ believes that the long time frame for achieving
ground water remediation levels is acceptable only in the context of the technical impracticability
of any alternatives.
EPA's responses to UDEQ's comments on the Proposed Plan are provided in the
Responsiveness Summary of this ROD.
9.2.2 Community Acceptance
Few comments were received from the community on the Proposed Plan. Based on these
comments and EPA's extensive work with 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 to verbal and written comments on the proposed plan are provided
in the Responsiveness Summary of the ROD.
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9.3 SUMMARY
Seven remedial alternatives were evaluated for the Murray Smelter Site. Through an
analysis using the nine criteria of the NCP, EPA has selected Alternative 3 as the Site remedy.
The remedy consists of the following components:
Ground water in the shallow aquifer contaminated with arsenic at levels above the
ACL of 5.0 mg/L dissolved concentration will be addressed via source control and
monitored natural attenuation as follows:
1. Source control will be implemented by excavation and off site disposal
of the principal threat wastes at the Site, an estimated quantity of 2000
cubic yards of Category I material 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 water 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
Rule, 40 CFR 300.440 and the generator requirements identified in Table
17.
2. Further source control will be implemented by excavation of
approximately 68,000 cubic yards of low level threat waste, Category n
material defined in Section 9.1 of this ROD. This material will be
consolidated within a repository system constructed within the Site
boundaries in accordance with the ARARs identified in Table 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 natural attenuation will address the residual ground water
contamination within and down gradient of these source areas. Monitored
natural attenuation will continue until shallow ground water achieves the
level of the ACL for dissolved arsenic of 5.0 mg/L. The intermediate
aquifer will also be monitored to demonstrate continued compliance with
the MCL of 0.05 mg/L dissolved arsenic.
4. The shallow aquifer will be monitored to evaluate the concentrations of
selenium at the established compliance points south of Little Cotton wood
Creek. The selenium monitoring is not for evaluation of the remedy, it is to
ensure continued compliance with the selenium MCL.
5 Institutional controls in the form of a Murray City ordinance
establishing an "overlay district" and restrictive easements that run with the
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land which both will prohibit the construction of new wells or use of
existing wells within the on-facility area and the western and eastern
portions of the off-facility area except for EPA approved monitoring wells.
Surface soils (0"-2") within the on-facility area contaminated with lead and arsenic
exceeding remediation levels of 1200 mg/kg arsenic as the 95% upper confidence
limit on the arithmetic mean within an EU or 5600 mg/kg lead as the arithmetic
mean within an EU will be addressed as follows:
1. Soils will be covered in place with barriers sufficient to prevent direct
contact. Such barriers may be pavement, landscaping, soil caps, or
sidewalks. Site development itself is expected to result in additional
protection of human health since land uses associated with unacceptable
human health risks will end. Also, development will result in the
construction of additional barriers (new buildings, roads, sidewalks parking
lots, and landscaping) over remaining surface soil and slag. Although no
unacceptable risks associated with exposure to slag were identified by
EPA, the development of the Site will ensure no exposure to slag in the
future.
2. Institutional controls in the form of a Murray City ordinance will
establish an "overlay district" which includes zoning to prevent residential
and contact intensive industrial uses within the former smelter operational
areas and will require maintenance of the barriers and controls on
excavated subsurface material within this same area. Restrictive easements
than run with the land will be established in addition to the overlay district
to prevent residential or contact intensive industrial uses.
Off-facility surface soils (0"-2") containing levels of lead exceeding 1200 mg/kg as
the arithmetic mean in individual residential yards or 5600 mg/kg as the arithmetic
meoii in commercial areas will be removed to a depth of 18 inches and replaced
v. Ah clean fill. Any landscaping disturbed in this action will be replaced. The
r "moved soil will be used on-facility as subgrade material in construction of the
repository system.
Surface water of Little Cottonwood Creek will be monitored to ensure continued
protection during the ground water natural attenuation process at the level of 190
ug/L as a 4 day average for trivalent arsenic and 360 ug/L as a 1 hour average for
trivalent arsenic and 100 ug/L for dissolved arsenic.
The established ecological study area will be monitored and the resulting
information will be used to reduce the uncertainties identified in the final
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Ecological Risk Assessment for the Site. Monitoring of wetlands will include
surface water, sediment and benthic macro invertebrates. Monitoring of terrestrial
areas will include plants and soil.
The goals of the selected remedy are to protect the intermediate and deep principal aquifer
at the level of the MCL for dissolved arsenic, to restore the shallow ground water to the level of
the ACL of 5.0 mg/L for dissolved arsenic established to protect Little Cottonwood Creek at its
beneficial use, and to remediate surface soils to levels protective of the reasonably anticipated
future land use. The remedy incorporates the construction of a new north-south access road
through the Site which will encourage future development of the Site and achieve Murray City's
goal of more appropriate land use through Site development.
Based on information obtained during the Site investigation and on a careful analysis of all
remedial alternatives, EPA believes that the selected remedy will achieve these goals. It may
become apparent during the monitored natural attenuation process for ground water that
dissolved arsenic levels have ceased to decline and are remaining constant at levels higher than the
ACL over some portion of the plume within the shallow aquifer. If it is determined on the basis
of system performance data that certain portions of the aquifer cannot be restored to the ACL,
EPA will prepare a justification for a waiver of the ground water ARAR based on technical
impracticability of achieving further contaminant reduction.
10. Statutory Determinations
Under its 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 121 of CERCLA establishes several other statutory requirements and
preferences. These specify that when complete, the selected remedial action for this Site must
comply with applicable or relevant and appropriate environmental standards established under
Federal and State environmental laws unless a statutory waiver is justified. The selected remedy
also must be cost-effective and utilize permanent solutions and alternative treatment technologies
or resource recovery technologies to the maximum extent practicable. Finally, the statute includes
a preference for remedies that employ treatment that permanently and significantly reduce the
volume, toxicity, or mobility crhazardous wastes as their principal element. The following
sections discuss how the selected remedy meets these statutory requirements.
10.1 Protection of Human Health and the Environment
The Baseline Human Health Risk Assessment identified unacceptable risks over the entire
on-faciiiry area associated with potential direct contact with lead- and arsenic-contaminated soil
and smelter debris by workers engaged in outdoor industrial activities. The assessment identified
substantially less risk (although still unacceptable in limited on-facility areas) associated with
exposure to the same materials under a scenario of commercial uses wherein workers would be
primarily indoors. The assessment also identified unacceptable risks associated with direct
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exposure to lead contaminated soil by residents and commercial workers in the off-facility area.
Potential ingestion of ground water from the shallow aquifer within the Site boundaries was also
predicted to result in unacceptable risk.
There is a large portion of the on-facility area where slag is exposed at the surface. It is
not likely that commercial or industrial workers or other adults will spend much time in areas of
exposed slag. Therefore, direct contact with slag by workers or residents is likely to be minimal.
However, area teenagers have been observed to visit the site in areas where slag is exposed. The
Baseline Human Health Risk Assessment characterized risks to teenagers who congregate in areas
along Little Cottonwood Creek and are potentially exposed to slag. 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 the principal threat at the site, undiluted arsenic trioxide, and will effectively address
the identified risk associated with potential migration of this material into shallow ground 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 designed with surface water management features. This action will
effectively control the infiltration of surface water into arsenic contaminated soil and prevent
further migration of arsenic into shallow ground water. 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 the protection of human health at the
Site:
(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 '.his exposure pathway; and
(3) Catalyst for development of the Site by providing the base for a roadway which is
expected to provide the necessary access to promote commercial uses. The Site
development will address the unacceptable risks associated with high contact industrial
outdoor activities.
The third component of the selected remedy is a comprehensive public and private
institutional controls package which will restrict the use of ground water within the Site
boundaries (with the exception of EPA approved monitoring wells) and restrict land uses other
than general commercial uses as defined by the Murray City land use code. The institutional
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controls package will also require that Site features such as roads, parking lots, and landscaping
which are functioning as barriers to human exposure be maintained. The institutional controls will
provide human health protection into the future. The Site development itself is expected to result
in protection of human health through the construction of barriers over remaining low level
surface contamination and slag. Although no unacceptable risks associated with exposure to slag
were identified, the development of the site will ensure no exposure 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 Characterization and
summarized in the final Site Characterization Report demonstrate that arsenic is being attenuated
on the aquifer materials and that iron oxide is the primary mineral phase responsible for the
attenuation of arsenic. Through the adsorption mechanism, the unacceptably high levels of
arsenic in the shallow aquifer will decrease over time at a rate that depends on the net flux 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 the attenuation and to ensure
protection of human health and the environment. Performance monitoring will include both
ground water and surface water monitoring. The effects of the source control actions of
Alternative 3 along with the monitoring activities are expected to demonstrate within 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 expects the remaining areas of the shallow aquifer to achieve the ACL within a time
frame of 100-150 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 exposure pathway of direct contact with
soils.
10.2 Compliance with Applicable or Relevant and Appropriate Requirements
The selected remedy will comply with all applicable or relevant and appropriate chemical
requirements presented in Tables 16-18.
10.3 Cost Effectiveness
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 million. The
estimated costs of other alternatives are presented in Tables 19 and 20.
The costs of Alternatives 2,3, 6, and 7 are very similar. Comparing Alternatives 2 and 3,
the additional effectiveness and protectiveness associated with off-site disposal of principal threat
wastes (Alternative 3) was judged to warrant the additional $200,000 cost. The difference
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between Alternatives 3, 6, and 7 is the option for remediating the off-facility soils. The cost of a
community monitoring and health education program is greater than the excavation of
contaminated soils and provides an approximately equal level of protectiveness. Alternative 7
includes tilling of soils. This Alternative is less costly than full soil removal but provides slightly
less effectiveness in some areas of the Site.
The costs of Alternatives 3, 4, and 5 are quite different reflecting different approaches to
ground water remediation. EPA hydrogeologjsts carefully considered the potential benefits of
extracting and treating ground water as described in Alternative 4. The effectiveness of this
option is limited by the characteristics of the aquifer which allow very little water to be extracted.
The addition of an extraction system will not increase the rate of improvement in ground water
quality over natural attenuation processes despite the additional cost. Also considered was the
amount of land which would be required for dedication of numerous ground water extraction
wells. 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 greater
problems with long term implementability, and greater incompatibility with Site development.
Alternative 5 includes in-situ ground water treatment in additional to source controls. This
alternative requires high operation and maintenance costs without appreciable increase in
effectiveness or protectiveness.
Balancing costs with effectiveness, protectiveness, and Site development considerations,
Alternative 3 is judged by EPA to be the most cost effective.
10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies (or Resource
Recovery Technologies) to the Maximum Extent Practicable
The selected remedy represents the maximum extent to which permanent solutions and
treatment technologies can be utilized in a cost effective manner for the Site. Neither extraction
and treatment nor in situ treatment of ground water were found to be more effective than natural
attenuation at reducing arsenic concentration in ground water. Yet both technologies are more
costly. The institutional controls of the selected remedy, while not permanent, will provide the
required level of protection during the period of natural attenuation of the ground water. The
source control measures will provide a permanent solutbn by consolidating the material in a
engineered repository system preventing contact by water, and people.
Of the alternatives that are protective of human health and the environment and comply
with ARARs, EPA believes that the selected remedy provides the best balance in terms of long
term effectiveness and permanence; reduction in toxicity, mobility, or volume achieved through
treatment; short term effectiveness; implementability; and cost. Overall protection of human
health and the environment, long term effectiveness, and cost were the most decisive criteria in
selecting Alternative 3 as the remedy.
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10.4 Pirfi-reuce for Treatment as a Principal Element
The selected remedy prescribes excavation and off-site disposal for the principal threat
waste. On-site treatment as a principal element was found not to be cost effective. However, the
principal threat wastes will be treated off-site before disposal. Therefore, the selected remedy
satisfies the statutory preference for treatment as a principal element to some degree.
Because the selected remedy will result in hazardous substances remaining on site, a
review will be conducted every five years after commencement of remedial action to ensure that
the remedy continues to provide adequate protection of human health and the environment.
10.5 Conclusion
EPA's choice of Alternative 3 for remediation of the Site is protective of human health
and the environment and is in accordance with CERCLA and the National Contingency Plan.
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RECORD OF DECISION
DECLARATION STATEMENT
SITE NAME AND LOCATION
The Murray Smelter proposed National Priorities List Site is located in the city of Murray,
Utah in Salt Lake County.
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the Murray Smelter Site
chosen in accordance with the Comprehensive Environmental Response, Compensation, and
Liability Act, as amended by the Superfund Amendments and Reauthorization Act and the
National Contingency Plan. This decision is based on the administrative record file for the Site.
The State of Utah does not concur on the selected remedy.
ASSESSMENT OF THE SITE
A period of 77 years of lead smelting operations at this Site (1872-1949) resulted in
impacts to the soil, ground water, surface water and sediment. Lead and arsenic have been
identified as the contaminants of concern to human health. In addition to lead and arsenic,
aluminum, cadmium, copper, mercury, nickel, selenium, silver, thallium, and zinc have been
identified as the contaminants of concern to ecological receptors. Risk assessment performed at
the Site in 1997 identified elevated risks to ecological receptors as a result of exposure to lead in
soils and sediments and selenium in plants. The risk assessment also identified unacceptable risks
to humans from ingestion of lead and arsenic in surface soils and the potential ingestion of arsenic
in shallow ground water. Although not currently used as a drinking water source, the shallow
aquifer at the Murray Smelter site meets EPA's and the State of Utah's criteria for classification
as a potential drinking water source, Class lib. An alternative drinking water source is readily
available in the deep principal aquifer and there is no near term future need for the shallow ground
water resource. Therefore, EPA believes that a relatively longer time frame for achieving
groundwater clean up levels is appropriate at this Site.
Actual or threatened release of hazardous substances from this Site, if not addressed by
implementing the response action selected in this Record of Decision, may present an imminent
and substantial endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE REMEDY
The remedial action selected by this ROD is the second of three response actions EPA
considers to be necessary at the Murray Smelter Site. EPA expects that an additional time critical
removal action will be required to address the potential for release of hazardous substances and
resulting health risks associated with the potential structural failure of the two smelter stacks
located on the Site.
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The remedy selected for the Murray Smelter Site in this ROD consists of the following:
1. Contaminated ground water. Source control will be implemented by excavation and off
she disposal of the principal threat wastes at the Site, approximately 2000 cubic yards of
residual undiluted arsenic trioxide. This material is considered a principal threat due to its
high mobility and its demonstrated ability to act as a source of ground water
contamination. In addition, direct contact with this material may result in acute human
health risks. Further source control will be implemented by excavation of approximately
68,000 cubic yards of low level threat waste, diluted arsenic trioxide or flue dust mixed
with soil, fill, or debris from former smelter structures. This material will be consolidated
within a repository system constructed within the Site boundaries. 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. Monitored
natural attenuation will address the residual ground water contamination within and down
gradient of these source areas. Institutional controls in the form of a Murray City
ordinance establishing an "overlay district" and restrictive easements that run with the land
both will prohibit the construction of new wells or use of existing wells (except EP
approved monitoring wells) within the on-facility area and the western and eastern
portions of the off-facility area.
2. Contaminated surface sofls. On-facility surface soil containing levels of lead and
arsenic exceeding remediation levels will be covered. The barriers will provide protection
by breaking the exposure pathways associated with long term direct contact with these
soils. Site development itself is expected to result in additional protection of human health
since land uses associated with unacceptable human health risks will end. Also, the
development will result in the construction of additional barriers (new buildings, roads,
sidewalks parking lots, and landscaping) over remaining surface soil and slag. Although
no unacceptable risks associated with exposure to slag were identified by EPA, the
development of the Site will ensure no exposure to slag in the future. Institutional
controls in the form of a Murray City ordinance will establish an "overlay district" which
includes zoning to prevent residential and contact intensive industrial uses within the
former smelter operational areas and will require maintenance of the barriers and controls
on excavated subsurface material within this same area. Restrictive easements that 'i«n
with the land will be established in addition to the overlay district to prevent residential or
contact intensive industrial uses.
Off-facility surface soils containing levels of lead exceeding remediation levels will be
removed and replaced with clean fill. The removed soil will be used on-facility as
subgrade material in construction of the repository system.
3. Surface water. Little Cottonwood Creek which forms the northern boundary of the
Site and to which shallow ground water discharges will be monitored 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.
-------
The goals of the selected remedy are to restore ground water to the level of the ACL of
5.0 mg/L for dissolved arsenic established to protect Little Cottonwood Creek at its beneficial use
and to remediate surface soils to levels protective of the reasonably anticipated future land use.
The remedy incorporates the construction of a new north-south access road through the Site
which will encourage future development of the Site and achieve Murray City's goal of more
appropriate land use through Site development. Based on information obtained during the site
investigation and on a careful analysis of all remedial alternatives, EPA believes that the selected
remedy will achieve these goals. It may become apparent during the monitored natural
attenuation process for ground water that dissolved arsenic levels have ceased to decline and are
remaining constant at levels higher than the ACL over some portion of the plume. If it is
determined on the basis of system performance data that certain portions of the aquifer cannot be
restored to the alternate concentration limit, EPA will prepare a justification for a waiver of the
ground water ARAR based on technical impracticability of achieving further contaminant
reduction.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with
Federal and State requirements that are legally applicable or relevant and appropriate to the
remedial action and is cost effective. This remedy utilizes permanent solutions however, the use of
alternative treatment technologies was found not to be practicable for this Site. The remedy will
achieve significant reduction in the mobility of the Site wastes through containment. The principal
threat will be addressed by excavation and off site disposal.
Because this remedy will result in hazardous substances remaining on site above health
based levels, a review will be conducted within five years after commencement of remedial action
to ensure that the remedy continues to provide adequate protection of human health and the
environment.
Max H. Dodson Date
Assistant Regional Administrator
Office of Ecosystems Protection
And Remediation
U.S. Environmental Protection Agency
Reeion VTU
-------
FIGURES
-------
•+> "*• L^I_^*----
'TV,^'-''^i"i^^.'**-*
5iW !il!r:s£
|^f£>^r * woulW*. """
v cr&#- '.
USCS. 7-1/3 MN. CXMO MAP. SLC SO.. '975
SCALE
nGUREl
LOCATION MAP
DATE: NQVERMSEr. '99
BY- 3Lh| CHECKED DE
McCULLEY. FRICK & OILMAN, INC
coniuttif>9 one
-------
LEGEND:
ON-FACILITY AREA
OFT-FACILITY AREA
ISZ INITIAL STUDY ZONE
EU Exposure Unit
NOTE:
1. SHADED AREAS ARE INSIDE THE PROPOSED STTE
BOUNDARIES FOR GROUNDWATER MONITORING.
SCALE
800
800 FEH
FORMER MURRAY SMELTER SITE
FIGURE 2
SITE BOUNDARIES
PROJECT: S324J2
REV.-
DATE. JANUARY.
BY: KT
: AK
McCULLEY. FRICK A OILMAN, INC.
-------
» I
I I
I J
11
11
i J
I t
I .
>/»> j \5)J«\5)Jl-4JtW. Or SCC
I
I
rOflueR SMCLICR f»ClLirr COUPONlf.
CXISIINC SURF»C£ fLMURlS
IIUURI- 3
I.CX:ATION OF HISTORIC*
SMIiLlFiR OPF-RATIONS
OATl MMMAT. «t
iY ICO |0€OB>
McCULLET. FRKK t CLMAN. II
-------
ROASTING CIS.
Scale
House
ROASIER
CAS
DUST
OXIDE ORES FOR
SMEL1ING BEOS
•3 Mill
(same as «2)
IRON ORE TINES
ir/o si AC UAIIE
t
IRON ORE. SETT. BARR. ETC. •<
OXIDE OR HICK GRADE ORE
0609
OXIDES ORES. COKE. IIUEROCK. CARFIELO SLAG HC.
l.imerock. Coke
l,on Ore. Etc.
Gorfields Slog.
DAL
Roast
Bins
nusi
SOURCE: SWAIN.1921
FORMER MURRAY SMELTER SITE
- PIGURIi 4 ~
PROCESS SCHEMATIC FOR
MURRAY SMELTER SITE, 1920
FtlOJCCT: 532«0
REV:
DA It SEPIEMBEn. 1996
DY: SCO | CHECKED; AK
McCULLEY. FRICK & OILMAN, INC.
-------
^Li6NMEN|]r NO,
LEGEND
INITIAL CONSTRUCTION
FUTURE CONSTRUCTIOh
i
LOCHNER
MGURE 5
-------
0 \ilJ4\Sl}« 4»D*C «l "CP
s.
, • «•••-• ~~~-*^i\
, ' '" . UIBN - Is- *Vv
4210 ^r -4^,. s,
LLCUill
UK-IOO
0 MlwIOVNC *fu 10
HP-?_
A\fU\ l1^*1*^ ** *«l1WTkA«T«K
4300 v~« ~ ,i,, O.M Ji.
M> trii IMMUMT* nit)
«*w»*c nocOMciMnuno* to.
SCNC
/
*"'•• \ i Hi. ! % , :
if ft "^ 1 - ^p • : ' .
_ > '•>.
, VP i. -
'o i
FORtfH WRRAr SMflTtR Sll
FKiURI- 6
SHALLOW AQUIFER
POTENTKJMETRIC SUBFACI
AND ARSEMC CONCENTWA7H
mOJiCI: SJJ4I
icv.
(MIL MMUMV. •«'
»> SCO |O€CXJD
McCULLEY. FR1CK t CULMAN. *
-------
u
11
[ J
I <
I 1
I J
I I
[ J
I I
[ J
»U«MNt*
CIMNI .
uw ineu
4ZMf
^«0a05j
51 I!---;'-".1
a1!-- \;j.
/ ' i I ___—-" • "'«. qtjw
,'/ I .-— ..- — — «"<
m I \ ^ * "\A^S k fTVVOlt
'•'- V
I:
•4JBO
I:
V -'
I«CH
KHCKH
*iUi-:;.riU-!i
;MCH
4300
— ^430C
-\^"^
:,.. JSj_|
f • • -jl : .-.'!
amiK rr**o 0*11 xriiMtA •>
REV. •» ucr loccrao •
McCULLEV. FRICK 1 OLMAN tit
-------
MGURE.
M.OODPLAIN AREA OF SITE
Floodplain
100 Year Floodplain
500 Year Floodplain
Liquefaction
High Liquefaction
Moderate Liquefaction
-------
FIGURE 9 $ummary Demographic Statistics
Murray, Salt Lake County, Utah
CERCLIS NO. 1^)980951420
OnMfile bifius
Ovfidlrtv Bounttarv
TSalt Lake County
Murray Smelter Area
Summary StmtitVct Within Or* HOf of the Sltt
-------
0\5I1<\<' » 0«C |i SCC
LLCQJD.
ts; e-i
ItAO CONCCNIRA1ION (n,g/K,)
FIGURE 10
r ;\u
i— \ \ ij^-11-^"
• * -^ \ \ _4— —
U— \ 1
LEAD CONCENTRATIONS
MEASURED M SURFACE
SOL M 192- « »wn isz-7
fMXCCI: «l«
«CV:
cutn. JMUM», Mr
IT uo IOCCMXI M>
MeCUU£Y. FRtCK 1 OUtKH. NC
-------
I/H
I.'IMI
'"' ' ISZ-1
I I'.til I.IAIII l| A'
LEGEND;
I'XK).
ILAO CONCtNIRAIKDN IN SOU. (rng/K,)
CAflpfN OR B*RE AREA
isz i BmiNCMnr
BOUNOABl
I IS/ - I IS ZOHIO TOR COMMCRClAi USE
FIGURE II
LEAD CONCENTRATIONS
MEASURED M SUIFACE
SOt. M ISZ-1
• T AJD |O€«H» ACK
McCULLET. FRICK • QUMAN. MC.
-------
1/97 DA532*\S32«-6*.QWG
N
LEGEND:
• ->- SAMPLE LOCATION WITH
'~~* LEAD CONCENTRATION (mg/Kg)
SCALE
300
300 FEiT
FORMER MURRAY SMELTER SITE
FIGURE 12
LEAD CONCENTRATIONS
MEASURED IN SURFACE
SOIL IN ISZ-8
PROJECT: 5324.0
REV.
DATE; JANUARY. 1997
BY: AJO OECKED: ACK
i
McCULLEY. FRICK & OILMAN. INC.
-------
'_•?» " ' II I' I • • I
(GtlJIRU fll(|vr)l
, W-15
>»* .•> Mi »-,
^ - JORDAN Rivrn SITTjS (NOT SHOtJ
* ' XBOO SOUTH .TTRrET IWIIXJC
. 33
-...,vv^
I iiirH urtij) conoNiioob CMKK )
* s«no SOUTH STTRKCT PRIIX:(I j,tn>i
(iirsiRFjiii or cnNn.uCHci irm>
unir. ronn»«i)oo c*rr.K)
. SS--I9 IIIRII W-ZO
DisTDinnrrD AI/INC \trnt
O)TT«IM»OOI) CREfK BCT»«N
l! I) «HI> JORIltN RIVTR
"»iit Trv. ]v<^ > "'5 '-L.J''* '•• '<
'/rJ^S,^.."^ I ;i
/-/- ;''*• "--T^v '' ' "~
Ss:,'
\
S« IZ<>
sn •'
«™,ri-M »• i-v
^ j > »•*» •»
; -Kr1
;ll
tffliKtr
3JOO SOUTH STUB
59-1 Thru S3-
pmnmuTto ALUNC.
inrtf OOTTOMWOOD CREEK
BmCCN 98-4 AND SI-I
I.
, .11 I
;i : i :
:\ •.;'-r---
AIAItCD WCORPORJTC9
9TTI CHARACTERIZATION REPORT
roMim MUWUT SMtLTIR StTt
mmiur. UTAH
(In r«ct)
500 0 500
(Approilmnte Only)
LCQEMD
MURRAY SUEl.TfR SITE BOUNDARY
^x^ CLOSED ntrstasioN
s. , SIIRFAre «»TTH BOTTOM StniUEMT BCNnnc
• MACROINVKRTCORATI SAMPLR- LOCATIONS
. S3-IS RIPARIAN SOIL SAMri£ 1-OrATlOM
FIGURE 13
BVB/ACB WATn. UPAUAN 0OfU BD
EKDMBNT, AND BKMTHJC MACIO-
I 8AMPLX UX3AT10M MAT
-------
i ~co:
., . '/ / i • i ' I'""1 J^
r . ' \ i ••"'••"»• IH«N.-I
i' • . i ', ••'P.1.:'1 / /•
' '
- lo<°. } /*:J
'
r^//w^
i;KOIINU»Tl'R AND SURFACE KTf.R
IOC«TION3
FOHMKR MUnnAY SMEI.TER Silt
-------
FIGURE 14 RESULTS FOR MALLARD - AUF ADJUSTED
NOAELHQ
XX
x X X X
^ ^
IB Invert
• Plant
B Sediment
O Soil
•Water
LOAEL HQ
' X X X X
B Invert
• Plant
H Sediment
DSoil
• Water
-------
FIGURE 15
RESULTS FOR KINGFISHER - AUF ADJUSTED
450 ,
^.nn
350 .
300 -
ocn
onn
2UU •
1*50 -
inn .
50 -
X
=^
Jf-
».*
=^
/•
«?"
X
tUJ
rf-
'x
c
i/X>
^*-<
k^^
•'•~*
-*
ff-
/
*>
NOAEL
t^^U
'/-•
H
/
Q
•y/
»•«•«
L*" T" A
X
/•
%
«TJ
*•*•«
**•«
»•*•«
»•••«
^c
^
/W
J%
t»4
»•*•<
»•*<
>*•<
''X
/-
^
%
yx
^w
»«•<
»•*«
»•«•«
^^^
»•«
*•«•«
»•*•<
^•4
/
• Plant
B Sediment
iD Soil
IB \Af~itnr
250
200
150
100
50
LOAEL HQ
!••*•«
1
»•*•<
B Invert
• Plant
B Sediment
O Soil
• Water
.J-" S* v
XX -' ' VX '
/X
-------
FIGURE 16
RESULTS FOR K1LLDEER
NOAEL HQ
160
140
120
100
I 80
60
40
20
0
B Invert
• Plant
; H Sediment
OSoil
• Water
LOAEL HQ
B Invert
• Plant
B Sediment
O Soil
• Water
-------
FIGURE 17 RESULTS FOR GOPHER
NOAEL HQ
250
•' X X
0 Invert
• Plant
B Sediment
O Soil
'•Water
LOAEL HQ
-------
TABLES
-------
TABLE 4 : LEAD AND ARSENIC IN SURFACE SOIL
Location
On-
facility
Off-
facility
Area
ELM
EU-2
EU-3
EU-4
EU-5
EU-6
EU-7
EU-8
EU-9
EU10
EU-11
ISZ-1
ISZ-2
ISZ-3
ISZ-4
ISZ-5
ISZ-6
ISZ-7
ISZ-8
Arsenic
Detection
Frequency'
13/19
13M7
18/18
13/70
19/20
19/20
19/19
10/10
10/10
9/10
8/10
19/19
7/10
10/10
16/16
16/16
11/12
10/10
7/12
Average
(ppm)
130
79
i;~:
418
100
432
418-
1674
118
69
19
106
16
55
43
42
52
126
76
Range
(ppm)
80^-630
BDL-360
9-7700
BDL-5400
BDL-520
BDL-5100
18-2200
64-5000
29-210
BDL-220
BDL-78
13-340
BDL-37
7-110
8-170
7-130
BDL-120
59-180
BDL-450
Lead
Detection
Frequency
19/19
17/17
18/18
20/20
20,70
20/20
19/19
10/10
10/10
10/10
10/10
19/19
10/10
10/10
16/16
16/16
12/12
10/10
12/12
Average
(ppm)
2905
2879
9548
1750
2754
2297
2524
6177
909
538
814
1299
241
768
377
426
657
1222
1062
Range
(ppm)
83-15000
98-9900
74-33000
37-15000
110-10000
71-7600
92-12000
570-25000
340-2000
150-1100
100-5700
250-3200
80-410
110-1600
1 10-780
130-640
120-1800
720-1800
66-7300
All data from Hydrometrics 1995a.
' Total number of samples with
b BDL = Below detection limit
detectable levels over total number of samples analyzed.
(about 5 ppm).
Baseline Human Health Risk Assessment M»y 1997
Document Control Number 4500-090-AOAC fift 2-S
THIS DOCUMENT WAS PREPARED BY ROY F WESTON. INC. EXPRESSLY FOR EPA IT SHALL NOT BE RELEASED OR
DISCLOSED IS WHOLE OR IN PART WITHOUT THE EXPRESS WRITTEN PERMISSION OF EPA
-------
TABLE 5 : LEAD AND ARSENIC IN SUBSURFACE SOIL
Location
On-
facility
Off-
faciliry
Area
EU-1
EU-2
EU-4
EU-5
EU-6
EU-7
EU-8
EU-9
EU10
ISZ-1
ISZ-2
ISZ-3
ISZ-*
ISZ-5
ISZ-6
ISZ-7
ISZ-8
Number
of sunons
2
1
1
!
19
4
^
^
2
2
1
^
•>
•>
i
i
->
Depth
Intervals
0-1 ft
. 1-2 ft
2-3 ft
3-4 ft
4-5 ft
0-2 in
2-6 in
6-12 in
12-18 in
0-2 in
2-6 in
6-12 in
12-18 in
Arsenic
Average
(ppm)
448
272
158
25
1224
3005
2851
1240
107
69
73
214
68
81
47
185
132
Range
(ppm)
BDL-1500
130-340
BDL-620
BDL-56
BDL-48000
BDL-34000
64-7200
13-7500
45-140
17-230
27-170
53-610
6-150
44-120
BDL-70
86-480
BDL-450
Lead
Average
(ppm)
8243
9480
1656
222
2259
3793
2751
6858
634
334
1089
520
486
443
588
2659
165
Range
(ppm)
50-16000
8200-10000
66-4800
61-600
57-22000
63-14000
520-9000
75-40000
430-1200
240-420
150-3200
87-1600
290-710
230-560
120-1000
550-7300
140-190
All data from Hydromeincs 1995a.
BDL = Below detection limn (about 5 ppm).
Baseline Human Health Risk Assessment Miy 1997
Documem Control Number 4500-O90-AOAC Pafe 2-10
THIS DOCUMENT WAS PREPARED BV ROY F WESTON. INC. EXPRESSLY FOR EPA. IT SHALL NOT BE RELEASED OR
DISCLOSED IN WHOLE OR IN PART WITHOUT THE EXPRESS WRITTEN PERMISSION OF EPA
-------
TABLE 6
SUMMARY OF CHEMICAL ANALYSIS FOR KEY ANALYTES
SHALLOW AQUIFER GROUND WATER
MURRAY SMELTER
WELL
JMM-OI
JMM-02
JMM-06
JMM-
0713
JMM-08
MS-GW-
\
MS-GW-
2
MW-IOO
MW-101
MW-102
MW-103
MW-104
MW-105
// or
SAMPLES
4
4
4
4
9
9
9
9
8
9
9
9
9
TDS
RANGE
787-1108
777 - 890
1325- 1489
1121 - 1367
549 - 957
868- 1126
981 - 1270
852 - 976
484-651
623 - 3409
1032- 1110
605- 1439
726-941
TOTAL ARSENIC
detects range mean
4 0.366-0.746 0.502
4 0.452-1.008 0.652
0
4 0013-0.019 0.015
9 0.016-0.078 0.039
9 0.487-30.14 10.98
9 2.87-6.539 4.10
1 DDL- 0.002 0.002
8 0.006-0.047 0.014
9 0.013-0.021 0.017
9 0098-027 021
8 BDL-0.012 0009
9 0.013-0042 0.022
TOTAL LEAD
detects range mean
2 0.064 -0.093 0.079
2 0.003-0.013 0.008
2 0002-0008 0.005
0
7 0.002-0007 0004
4 DDL-0.003 0.005
4 DDL-0.005 0.002
6 DDL-0.035 0.01
6 I3DL-0.301 0.062
1 DDL-0.001 0.001
4 BDL-0.003 0.002
2 BDL-001 0002
6 BDL-0079 0.02
TOTAL SELENIUM
detects range mean
0
0
0
0
0
8 0.015-0.192 0.065
8 0.036-0.056 0.046
0
6 BDL-0.016 001
3 BDL-0.007 0.004
0
6 BDL-0.018 0.012
8 0.016-0053 0037
-------
TABLE 6
SUMMARY OF CllliMICAL ANALYSIS FOR KEY ANALYTIC
SI IAIJ.OW AQUIFER GROUND WATER
MURRAY SMELTER
MW-106
MW-107
MW-108
MW-109
MW-110
MW-III
MW-112
MVV-113
MW-114
UTDN-I
WELL 1
WELL 2
WELL 3
9
9
9
7
9
9
9
2
2
10
8
9
9
1491 - 1895
2126-2784
995- 1264
1082-1345
1329-1530
658- 1578
602 - 1 1 24
1524-1544
490-506
759-1265
535-801
1434-1782
843-1309
9 23.85-31.06 26.74
8 BDL-0019 0014
6 BDL - 0 02 0.006
7 0014-0022 0018
9 1689-2388 2.10
9 2903-4535 3.60
9 0.052-0.134 0.104
2 0015-0.021 0.019
2 0.015-0021 0.018
10 0.116-0.27 0.176
8 ' 014-0.316 0.245
9 1439-1.974 1.68
9 0.134-0.236 0.173
6 BDL-0079 002
1 BDL-O.OOI 0.001
3 BDL-0.026 0006
4 BDL-0012 0003
0
7 0013-0212 0.107
7 0027-0.084 0.039
0
0
8 0.05-0.101 0.069
5 BDL-0.086 0.024
3 BDL-0.008 0.006
7 0.081-0.214 0.139
8 0.07-0.137 0.104
8 0.026-0.186 012
8 0.041-0.095 0.076
0
8 0.104-0. I'll 0.139
8 0075-0.166 0115
4 BDL-0.059 0.016
0
0
9 0.011-0.063 0.036
0
1 BDL-0.006 0.003
8 0011-0.0790.028
NOTES
All values are reported in units of mg/L
Values of one half the detection limit were substituted for below detection limit data in calculation of mean values.
-------
TABLE 7 Exposure Point Concentrations for Surface Water
Part A: Low Flow
Chemical
Aluminum
AfMnie
Cadmium
Copper
Leed
Selenium
Zinc
Up(ntiunt
(n-2)
TOUT
0.193
(0.0025]
[0.00025]
(0.005)
0.008
[0.0015]
0.021
Dissolved"
[0.05]
[0.0025]
(0.00025)
[0.005]
0.003
[0.0015]
(0.01)
Onxitc
(a*2)
Total
0.209
0.048
[0.00025]
(0.005)
0.004
[0.0015)
0.035
Dissolved
(0.05)
0.044
0.0012
(0.005)
[0.001]
[0.0015]
[0.01)
Downgndient
-------
TABLE 8 Exposure Point Concentrations for Sediment
QicnxicAl
AltirnimiTM
Aneoic
Cadmium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
UpgnditBl
(n«lO)
5523
29
0.63
62
302
0.1
37
0.55
2.3
(0.5)
526
Onatc
(n=10)
6465
70
3.1
III
1699
OJ3
63
0.78
SJ
[0.5]
2389
DowngrmdicBt
(n«UO)
5938
32
1.4
409
356
0.18
116
0.48
3.6
[0.5)
694
Dcprenioa
to* 10)
11893
492
51
162*
9058
OJO
40
58
19
32
58600
All value* itpenxl in uniu of mj/kg dry weight. EPCi tre m» minimum of th* UCL95 or
deecribed in th* text.
[ ] Vtluee in bnckeU iifir»««iii 1/2 quantiution (reporting) I'"""
Se* Appendix C for dau end fumnury tuodict.
detactad ytliw «•
Drift Final Ecoloficai Riak Aaeeeaawot Septfimher 1997
Docunem Comrol Number 4X10-090-AOKP Paf* 3-3
THIS t>OCUMENT WAS PREPARED BY ROY F. WESTON. INC. EXPRESSLY FOR EPA. IT SHALL NOT BE RELEASED OR
DISCLOSED IN WHOLE OR IN PART WITHOUT THE EXPRESS WRITTEN PERMISSION OF EPA.
p:\mamyvecoveooiezi-2.wp5
-------
TABLE 9 Exposure Point Concentrations for Riparian Soil
CbanioJ
Aluminum
Aneaic
Cadmium
Copper
Leed
Mercury
Nickel
Selenium
Silver
TVitlitim
Zinc
Upgradimt
-------
TABLE 11
SUMMARY OF ARSENIC CONCENTRATIONS IN SURFACE WATER
MEASURED IN QUARTERLY MONITORING EVENTS
MURRAY SMELTER SITE
SAMPLE
DATE
7/22/96
12/6/96
1/14/97
4/1 1/97
7/15/97
10/8/97
UPSTREAM
AVERAGE
DISSOLVED
0.007
<0.005
<0.005
<0005
0.007
0009
UPSTRIiAM
AVERAGE
TOTAL
0.007
<0.005
<0.005
<0.005
0.008
0008
ON-SITG
AVERAGE
DISSOLVED
0.167
0.173
0.288
0.176
0.051
0.123
ON-SITE
AVERAGE
TOTAL
0.146
0.201
0.299
0.161
0.046
0.11
DOWNSTREAM
AVERAGE
DISSOLVED
0.129
0.164
0.2
0.181
0.042
0.053
DOWNSTREAM
AVERAGE
TOTAL
0.107
0202
0.255
0.184
0.043
0.061
WETLANDS
DISSOLVED
026
0.201
0.146
WETLANDS
TOTAL
0.266
0.232
0.175
All results arc reported in units of milligrams per liter.
Where no result is reported, no sample was collected on that date.
-------
TABLIi 12 ;uSKS FROM ARSENIC IN SURFACE SOIL AND DUST
l>ii|Nilalion
Resident
NU Woiker
Cl- Woiker
Location
On facility
OH facility
On facility
On facility
Area
EUI
EU9
EU 10
Ell II
ISZ I
ISZ 2
ISZ3
ISZ4
ISZ 5
ISZ 6
ISZ7
ISZR
EU 1
EU 1
Ell)
HI) 4
EU5
Ell 6
F.U-7
EU 1
EU2
El) 3
F.U-4
r.u-s
EII6
EU7
Arsenic Concentration (ppm)
Mem Ma* I:PC
1674 5(100 5000
118 210 210
69 220 220
1') 78 62
106 310 222
If. 37 37
55 110 11(1
45 170 75
42 130 65
32 121) 120
126 180 158
76 450 450
130 630 630
79 360 360
1172 7700 7700
418 5400 34IX)
100 320 283
432 3100 1788
418 2200 1220
130 630 630
79 360 360
1172 7700 7700
4IR 3400 5400
UK) 520 285
432 5100 1788
418 2200 1220
Nmicancei IIQ*
Av?
IE +00 3B400
8E42 IE-01
SE-02 IE 01
2E 02 3E 02
7E02 11:01
2E 02 3E 02
41: 02 8F.-02
31: 02 5E 02
M: 02 5E 02
41- 02 81-02
91:02 IE 01
5E 02 3E 01
3E4H lf.4)\
2E 02 8E 02
3EOI 2BiOQ
9E02 iE4 IE t (X), cancel risk > IE (M)
• Hie first value shown is based on (lie mem concentration, and the second value shown is based on the EPC (usually the manimum)
-------
TABLE 13 POTENTIAL RISKS FROM ARSENIC EST GROUNDWATER
Population
Resident
Worker
Location
On-site
Off-site
On-site
Aquifer
Shallow
Intermediate
Shallow
Intermediate
Well
MW-100-
MW-1011
MW-102
MW-103
MW-104
MW-106
MW-101D
MW-104D
MW-102
MW-105
MW-106
MW-I07
MW-108
MW-109
MW-110
MW-tll"
MW-1I2
GW-1
GW-2
Well 1
Well 2
Well 3"
UTBN-1
MW-105D
MW-108D
MW-109D
MW-112D
GW-1 A
GW-1AR
GW-2A
Concentration
3
6
18
270
6
27.180
3
19
18
13
27.180
3
3
14
2.347
2,903
52
1.287
2.870
216
1.974
236
270
25
3
69
39
790
6
439
Chrome HQ
Avg RME
1E-01 2E-01
3E-01 5E-01
8E-01 2E4-00
: IE+01 2E+01
3E-01 5E-01
iSIE+Or 2E+03
lE-01 2E-01
8E-01 2E*00
4E-01 6E-01
3E-01 4E-01
; "SE+02"i 9E+02
5E-02 8E-02
5E-02 8E-02
3E-01 5E-01
-'SE-HHT-fiErMJl
.s6E+01^9E*Oi
"lE+OOlrZEifOO
:I3B+3I1:"4£*01
"6E+OJ 9E*01
I4£*OOM7E*00
I4E+OI? 6E4-01
{fSE+OOVvBErHJO
;;5E-fOO^:::?E4-00
5E-01 8E-01
5E-02 8E-02
IE +00 2E+00
8E-01 1E+00
2E+0I 3E+01
1E-01 2E-01
9E-I-00 IE-HJI
Cancer Risk
AVE RME
6E-06 4E-05
IE-OS 1E-04
5E-05 3ErO*
7EW 5E-03
IE-OS 1E-04
:? ••'7E4XZ::' AB-OI
6E-06 4E-05
5E-05 ,3E«4
1E-05 1E-04
8E-06 7E-05
:r2E^r-:'.T«ra
2E-06 lE-05
2E-06 IE-OS
9E-06 7E-05
2E-03 lE-m
2E-03 2E-C2
3E-05 3E?0»
8E-04 7E-Q3
2E-03 1F02
1E-04 1EX)3
1E-03 i&ffi
2E-04 1E-03
2E-04 1E-03
2E-05 1E-04
2E-06 IE-OS
4E-05 4EO*
3E-05 2E«4
5E-W 4E«3
4E-06 3E-05
3E-W 2E«3
Shaded cells indicate wells where risks from arsenic exceed typical EPA guidelines (HQ > IE+00, cancer risk
> 1E-04)
' Well located in an up-gradient location
" Well is completed in slag
Baseline Human Health Risk Assessment May 1997
Document Control Number 4SOO-090-AOAC Page S-S
THIS DOCUMENT WAS PREPARED BY ROY F WESTON. INC EXPRESSLY FOR EPA IT SHALL NOT BE RELEASED OR
DISCLOSED IN WHOLE OR IN PART WITHOUT THE EXPRESS WRITTEN PERMISSION OF EPA.
-------
TABLE 14 RISKS TO WORKERS FROM LEAD IN SURFACE SOIL AND DUST
Exposure
Area
EU-1
EU-2
EU-3
ElM
EU-5
EU-6
EU-7
Mean Lead
Concentration
(ppmj
2905
2879
9548
1750
2751
2297
2524
Predicted Blood Lead Distribution
in NCI-Workers
CM
(ug/dL)
4.0
4.0
7.8
3.3
3.9
3.6
3.8
95th
(ug/dL)
8.1
8.1
16
6.8
7.9
7.4
7,7
Pll.l1
0.9%
0.9%
20%
0.3%
0.8%
0.5%
0.6%
Predicted Blood Lead Distribution
in Cl-Workers
GM
(ug/dL)
12
12
35
8.3
12
10
11
95th
(ug/dL)
25
25
71
17
24
21
22
Pll.l'
•••' 59*. <• '
58%
••• 99*5;:
- 15X-V-:. '
• 55% •.-..•:
••• 41*?--."
•.-:- 4V&* •
PI 1.1 = probability of a worker exceeding a blood lead level of 11.1 ug/dL. For convenience, values above 5%
have been shaded
Baseline Human Health Risk Assessment May 1997
Document Control Number 450OO90-AOAC Page 5-10
THIS DOCUMENT WAS PREPARED BY ROY F WESTON. INC EXPRESSLY FOR EPA. IT SHALL NOT BE RELEASED OR
DISCLOSED IN WHOLE OR IN PART WITHOUT THE EXPRESS WRITTEN PERMISSION OF EPA.
-------
TABLE 15 RISKS TO CHILDREN FROM LEAD IN SURFACE SOIL AND DUST
Exposure
Area
EU-8
EU-9
EU-10
EU-11
ISZ-1
ISZ-2
ISZ-3
ISZ-4
ISZ-5
ISZ-6
ISZ-7
1SZ-8
Mean Lead
Concentration
(ppm)
6177
909
538
814
1299
241
768
391
426
657
1222
1062
Predicted Blood Lead Distribution in Children
CM (ug/dL)
28.6
8.1
5.6
7.5
10.4
3.4
7.2
4.6
4.8
6.5
10.0
9.0
95th (ug/dL)
50
14
10
13
18
5.9
13
8.0
8.0
11
17
16
P101
Kv }•. >99%
«;•;:.:;- .,:\.26%'. V. v
4%
19%
•^- . ' 53.*;:- '-
0.1%
••••'"• 15% ';•:
0.9%
1.4%
.;;.:;:>;, -,-$;o:*:: ' :-"-;-
&.v;-."48%V :- :;:;.:
^.:---::"37B'§.v:-'"":V":
P10 = probability of a child exceeding a blood lead level of 10 ug/dL (%). Shaded cells identify
locations where [he value of P10 is higher than EPA's goal of no more than 5%.
Baseline Human Health Risk Assessment May 1997
Document Control Number 4500-090-AOAC Page 5-8
THIS DOCUMENT WAS PREPARED BY ROY F WESTON. INC. EXPRESSLY FOR EPA. IT SHALL NOT BE RELEASED OR
DISCLOSED IN WHOLE OR IN PART WITHOUT THE EXPRESS WRITTEN PERMISSION OF EPA.
-------
TABLE 16
CIIIiMICAL SPECIFIC ARARS
Requirement
Citation
Description
Notes
Utah Primary nicnking Water Standards
(JACK3U9-IUJ-2
l-slablishcs niaxiinum contaminant levels
of 0.015 mg/L Tor lead and 0 OSnig/l Tor
arsenic as primary drinking water
standards
relevant and appropriate for
groundwater at the Murray Smeller
Sile
National I'linmiy Drinking Water Standards
•10CFK Ml II
Establishes the maximum conlnminanl
level for arsenic of 0.05 mg/L
rclcvnnl and appropriate for
groundwaler al the Mutiny Smeller
Silc
Nnlionnl 1'iimary Drinking Water Standards
•NICI-K Ml 80
l-slablislies a lead action level of 0 01 5
mg/L. Regulations establish a licalmcnl
technique triggered by excecdance of tlie
action level in more Ihan 10 (intent of lap
water samples collected during any
monitoring period.
relevant and appropriate for
groundwnler at the Muiiay Smeller
Site
Definitions and General Requirements of Utah Water
Quality Act
IMC R317-1
Provides definitions and general
requirements for water quality in the State
of Utah
Applicable to ground water and surface
water al the Murray Smelter Site
Adminislialive Rules for Groundwaler Quality Protection
IJAC R317-6-6 AC and R317-6-
6.4D
I JAC R317-6-2
Establishes requirements Tor issuance of a
groundwaler discharge permit al an
existing facility. Permit limits may be
either groundwaler quality standards or
alternate concentration limits.
Groundwaler quality standard for arsenic
is 0 05 mg/l, for lead is 0.015 mg/1.
Alternate concentration limits are
established on a site specific basis. The
Alternate Concentration Limit for the
Murray Smeller Silc is 5.0 nig/1.
Substantive requirements are relevant
and appropriate for groundwaler at
Mm ray Smeller. Nolc thai the
groundwnler quality slarxlaid need not
be met if it is demonstrated Ihnt an
alternate concentration limil (AC1.) is
protective. At the Miurny Smeller Site
the ACL is the relevant and appropriate
requirement for on site groundwaler in
the shallow aquifer.
-------
TABLE 16
CHEMICAL SPECIFIC AKARS
Slftiulaids of Quality for Wnlcrs of (he Stale
UACR3I7-2-6, R317-2-7.
K312-2-13. and
IU17-2-14
I'sUblislies use designations of Class 2D,
Class 3A, and Class 4 fur the segment of
Little Collnnwood Creek which borders
the Murray Smeller site. Establishes
water quality standards applicable lo each
class. Water quality standards for divalent
arsenic arc 190 tig/1 (<1 dny average) and
360 ug/l (I hour avciage) for Clnss 3A.
Water quality slandaid foi dissolved
arsenic is IIX) ng'l for Clnss 4 Water
rjunlily slandnrds liu lead ate 3 2 ug/l ('I
day average) and 82 ug/l (I limn nvcingc)
for Class 1A and 100 IIK 1 Tor Clnss 1
Applicable lo snif.icc walcr of I.idle
Cottonwood Cieck
-------
TABLE 17
ACTION SI'KCIFIC ARAKS
(•.mission Standards
l-ugilivc Dust I'.mission Standards
(iimiiul Water Protection Standards for Owners and
< tpcralois (if 1 la/ardous Waste Tiealnienl, Storage, and
Disposal 1 acilihcs
(icncial |:ncility Standards:
Construction Qiinlily Assurance 1'iogram
General Facility Standards:
Location Standards for Hazardous Waste Facilities
Standards for Control of Installations, Slate Adoption of
National Ainl>icnt Air Quality Standards (NAAQS)
OfTSile Managcmcnl ofCHRCLA Wastes
Well Drilling Standards
UACR307-I-4
UACR.107-12
10 Clll Part 264 97
UACR1I5 86
10 CI R I'arl 26-1 99
40 Clll 264 19
UACR3 15-8-2.9
40CFR264.I8
UACRJ07-1-3
40 CFR 300.440
UACR3I5-5
'10 CI'K 262.10 through 262 44
UAC R655-1
Establishes air quality standards Tor visible
emissions, I'M 10, and internal combustion
engines
Establishes air quality standards for
fugitive dust emissions
Establishes general ground water
monitoring requirements for treatment
storage and disposal facilities
Establishes requirements fur compliance
monitoring program
lislablishes requirement for a construction
quality assurance program lo ensure thai
constructed units meet or exceed all
design criteria and specifications
Establishes site characteristics which arc
unsuitable for location of hazardous waste
management units.
lislablishes NAAQS as requirements for
ait quality. NAAQS for PMIO is SO
ug/in* annual arithmetic mean, and 1 SO
ug/m1 24 hour maximum.
NAAQS for lead is 1 5 ug/m' maximum
quarterly average.
Establishes requirements for off site
management of CKRCI-A wastes
Establishes hazardous waste generator
requirements
Establishes standards for drilling and
abandonment of wells
Applicable to emissions generated
during remedial activities
Applicable lo fugitive dust emissions
generated during remedial activities
Relevant and appropriate lo ground
water at Murray Smelter Site
underlying any on site waste
man.igrmcnt units constructed as part
of the remedial action
Relevant and appropriate to
construction of surfiice impoundment.
waste pile, and land fill units
constructed as part of Ilie remedial
action
Portions are relevant and appropriate It
alternatives which include
consolidation of wastes on site
Relevant and appropriate lo air
emissions resulting from remedial
activities at Murray Smeller
Applicable to alternatives tlml involve
off site management of hazardous
waste
Applicable to installation or
abandonment of monitoring wells
-------
TABLE 17
ACTION SPECIFIC ARAKS
Definitions and General Rc(|iiircincnls for Ait Conservation
()ACR3f)7-l-lflndR307-|-2
Outlines gcnerol requirements and
provides dcfinilions for Air Conservation
Rules
Applicable to nllem.ilivcs thai may
CBIISC air emissions
Standards for Control of Installations
UACK307-1-3
Requires implementation of Hcsl
Available Control Technology mid
specifies criteria for NAAQS
Relevant and appropriate lo activities
such as grading and excavation where
fugitive dust could he generated
Definitions ami Ocncral Requirements for Solid and
I lazmdons Waste
UACR3I5-I andR3IS-2
Outlines general reqnirrmenls and
piovides definitions for Utah Solid and
11,1/iHiloiis Waste rules
Applirnhle lo Ilie oi.inngcincnl of
lia/.ardous wastes generated on site
Landfills
UACR.m 8 M
HACR3I5-8 7
40 CFR 264.310
40 CIH 261.301
40 CFR 264.303
standards for design and
closure of landfills
Requirements arc relevant and
appinpriitle lo Alternatives which
include consolidation of wastes on site
Land Disposal Rcsliiclions
UACR3I5-13
40 Cl R I'arl 268
Outlines restrictions on land disposal of
hazardous waste
Relevant and appropriate to on site
placement of hazatdous waste
generated during remedial actions.
Note that movement of waste with an
area of contamination docs not
constitute placement.
('Iran- up Action and Risk-Based Closure Standard
UACR3I5-10I
Rstablishes risk based closure standards
for management of sites contaminated
with hazardous waste or hazardous
constituents
Relevant and appropriate lo Murray
Smeller
Corrective Action Clean Up Policy for CliRCLA and
Underground Stoiage Tank Sites
MAC R311-211-2, R311-211-3,
R3II 2ll-4,8ndRJII-21l-
5(a)and O
Establishes minimum standards fur clean
up of hazardous substances for water
related corrective actions. The policy
allows for establishment of clean up levels
above the minimum standards under
certain conditions.
Applicable lo gronndwatcr at Murray
Smeller
-------
ACTION SPECIFIC ARAKS
I Mali 1'ollnlnnl Discharge Rliminalinn System
Refinements
UACK3I7-8
Kslablishcs general tcqiiiicincnls,
definitions, mid standaids Tot point source
discharges of pollutants into surface water
bodies in Utah and establishes pic-
Irealment reqiiiremcnls for discharge to a
publicly owned treatment works
Applicable to point source discharges I
Little Coltonwood Creek from the
Murray Smeller site
Closure anil Post-Closure:
I'osl clnsuie C'nic and Use of l'to|icity
•10CI-K26<1 117
lislablishes iniiiiinnm requirement.1! for
inoniloiing, reporting, and mninlciiarice of
closed har/udous waste mnnigemenl units
Uclevnnl and appropriate to
consolidation units consliiiclcd as p.iit
of the remedial action
Closure and Post Closure:
I'osl -closure plan
<10CH<264.II8
(•slablishes requirement for written plan
identifying activities that will be carried on
alter closure ofcach disposal unit
Portions arc relevant and appropriate d
consolidation units constructed as part
of (he remedial action
Closure and Post Closure:
Cost -closure notices
40CFR2M 119
lislablishes requirement to record
certification ofclosure via a notation on
the property deed to the facility end
notification that the land has been used to
manage hazardous waste
Portions aic relevant and appropriate t<
consolidation units constructed as pail
of the remedial action
-------
TABLE 18
I,OCA! ION SPECIFIC ARARS
Arrhcologic.il and I lisloric Preservation Act
•IOCIRSubpartC630l
Establishes procedures for preservation of
historical and archaeological features
which might be destroyed through
alteration or terrain as a result of a Federal
construction project or i Federally licensed
activity or program
Applicable if such features me found
on the Site
I Jalional I lisluitc Preservation Act
-inCH* Subparl C 6 30IOand
\(> Cl R 8(10
Kequires Federal agencies to consider the
cDecl of any Federally assisted
undertaking or licensing nn any district,
sile. building, structure, or object that is
included in 01 eligible lor inclusion in the
national register of historic places.
Applicable ifrcincdi.il activity affects
propcily lisled or eligible lur listing on
the National Kcgisliy of Historic Plncc
Kxeculive Order on Protection of Wetlands
Executive Order 11990
Requires Federal agencies to avoid, to the
extent possible, the adverse impacts
associated with the destruction or loss of
wetlands and lo avoid support of new
construction in wetlands if a practicable
alternative exists
Applicable lo any areas classified as
wetlands on the Murray Smeller sile
Clean Water Act
•10 CFR Parts 230, 231
Requires that actions not discharge
dredged or fill material into wetlands
without a permit.
Substantive requirements of permit arc
applicable for actions at the Murray
Smeller sile which involve discharge ol
dredged or till material into classified
wetlands.
Fish and Wildlife Coordination Act
-10 CFR Part 83
Requires that actions taken in areas that
may a fleet streams and rivers be
undertaken in a manner that protects fish
and wildlife
Applicable to activities conducted in
I. idle Collonwood Creek
nndangercd Species Act
50 CFR Parts 17 and 401
Requires that Federal Agencies ensure that
any action authorized, funded, or carried
out by the agency is not likely lo
jeopardize the continued existence of any
threatened or endangered species or
destroy or adversely modify critical
habiUt
No critical habitat or endangered
species have been identified at the
Murray Smeller sile.
-------
TABLE 18
LOCATION SPECIFIC ARARS
Migratory Biid Trcaly Act
16 USCS 703
Establishes Ilial is unlawful (o lake or
possess any migratory nongame bird or
any part of such migratory noiigainc bird
Applicable to migratory birds at Ilic
Murray Smeller site
-------
APPENDIX A
-------
RESPONSIVENESS SUMMARY
PROPOSED PLAN FOR
MURRAY SMELTER PROPOSED NPL SITE
PARTI:
COMMENTS RECEIVED FROM THE UTAH DEPARTMENT OF ENVIRONMENTAL
QUALITY (UDEQJ
UDEQ stated concerns that selenium has been detected in the shallow ground water at the Site in
concentrations which exceed drinking water standards for that chemical.
EPA Response: The over-riding environmental concern associated with shallow ground water
within the on-facility boundaries is arsenic which has been detected at levels 100-1000 times
drinking water MCL. In comparison, selenium has been detected at various locations within the
on-faciiity boundaries at levels twice the drinking water MCL. Unlike arsenic, the selenium in
shallow ground water has not affected the quality of Little Cottonwood Creek. EPA's selected
remedy includes continued monitoring of selenium in shallow ground water and institutional
controls which will prevent exposure to selenium by prohibiting the installation of ground water
wells except for the purpose of monitoring. The selected remedy is thus protective.
UDEQ also expressed concern about the arsenic loading of Little Cottonwood Creek as a result
of a point discharge from the 48 inch reinforced concrete pipe culvert which runs along State
Street.
EPA Response: The selected remedy requires control of the Site related source(s) of this arsenic
discharge and further requires compliance with surface water quality standards for Little
Cottonwood Creek. The details of the source control activities will be developed as pan of
remedial design.
UDEQ provided an evaluation of responses to comments they submitted on the draft Feasibility
Study. The responses were prepared by Asarco. On the basis of Asarco's responses to UDEQ's
and EPA's comments on the document, EPA approved the Final Feasibility Study. EPA notes
that UDEQ was provided Asarco's responses on August 27, 1997.
UDEQ Comment 1: UDEQ requests numeric clean up levels and confirmatory sampling.
EPA Response: EPA established remediation levels in Section 8.3 of the ROD. The details of
confirmatory sampling will be developed as pan of remedial design.
UDEQ Comment 2: UDEQ is concerned about the remedy's ability to comply with the ground
water MCL for arsenic given the long time (>150 years) for achieving the MCL predicted in the
Feasibility Study.
-------
EPA Response: In the ROD EPA provides the rationale for why the conditions at Murray
Smelter meet those established in CERCLA Section FS2 for the establishment of an Alternate
Concentration Limit in lieu of the MCL for arsenic. The evaluation of how the selected
alternative will meet this ACL within reasonable time^rame given the Site specific circumstances
is contained in Section 9.1 of the ROD. EPA agrees with the statements in the final Feasibility
Study that the MCL will ultimately be met. The mechanisms of natural attenuation will continue
in perpetuity such that ground water quality will continue to improve resulting in the achievement
of restoration albeit in a very long time.
Also in Comment 2, UDEQ requests more specific information about how ACLs will be
established at the Site.
EPA has included the development of the ACL for arsenic as Appendix C to the ROD.
UDEQ Comment 3: UDEQ objects to Asaarco's statements which suggest that State ARARs
were not identified in a timeiy manner.
EPA Response: EPA notes that l*DEQ has never responded to EPA's September, 1996 formal
request for an ARARs analysis from the State. While it is accurate to state that many discussions
have occurred between the State and EPA on the identification of State ARARs, UDEQ has only
provided a table with no indication of whether that table was to be considered official or final
identification of State ARARs :br this Site.
UDEQ also requested justification for why chemical specific RCRA ground water maximum
concentration levels were not identified as ARAR.
EPA Response: EPA did not identify these standards because they ae not applicable (Murray
Smelter is not a treatment storage or disposal facility) and are not relevant and appropriate given
the Site circumstances are appropriate for establishing an ACL.
EPA included the following ARARs in the ROD in response to UDEQ' comments:
A. UAC R315-8-6 is identified as relevant and appropriate.
B. Utah's ground water protection rule is identified as relevant and appropriate.
C. EPA's off-site rule is identified as applicable.
D. UAC R315-5 is identified as applicable.
E. UAC R3158-14 is identified as relevant and appropriate.
F. UAC R311-211-2 is identified as applicable.
G. UAC R317-1 is identified as applicable.
-------
L*DEQ Comment 4: UDEQ is concerned about the lack of detail regarding the cover design for
the on-Site repository system.
The requirements for the cover are identified in the ROD. The further development of the details
of the cover is a remedial design activity.
UDEQ provided an evaluation of how well Asarco responded to UDEQ's comments on the draft
Feasibility Study. This evaluation is noted by EPA. EPA considers the responses provided by
.Asarco to be adequate. It was on the basis of Asarco's responses to these comments as well as
EP.Vs comments that EPA approved the Feasibility Study. We assume that this further
evaluation by UDEQ is provided for the record and as such will be included as part of the
Administrative Record for the Site.
PARTII
COMMENTS RECEIVED FROM ASARCO
Asarco commented that the monitoring requirements included in the ROD to support efforts to
reduce uncertainties in the ecological risk assessment may not be required if the wetlands area of
the Site are filled during Site development. Asarco also suggests that there may be other options
to monitoring which will reduce the uncertainties in the ecological risk assessment.
EPA Response: EPA agrees with the comment and has included language in the ROD indicating
that in the event the wetlands are filled, the associated exposure pathways will be broken. The
ROD also includes the requirement that if the wetlands remain, monitoring will be required. The
majority of the ecological risk at the Site is associated with the wetlands. As development plans
become more clear, monitoring will be incorporated into the remedial design or deleted as
appropriate. Currently, there is not enough information to assess how the planned Site
development will affect the wetlands.
Asarco also commented that the Proposed Plan was not clear in describing whether the proposed
cover for slag is to be an interim or permanent cover. Asarco further questioned the basis for
requiring a cover for slag. .Asarco also enclosed the attached memorandum supporting their view
that a cover for slag is not required.
EPA Response: EPA agrees with .Asarco's comments. Language has been added to the ROD to
clarify that there is no need to cover the slag as part of the remedy for the Site. ThefOD also
makes it clear that EPA expects the slag will be covered in the near future as pan of Site
development.
-------
ENVIRONMENTAL Sf
Memorandum
To:
From:
Date:
Donald A. Robbins
Rosalind A. School'.
October 23, 1997
Ph.D -j(s<3^
/^^
Subject: Weathering of Slag a: the Murray Smelter Site
Recently a question has arisen regarding potential future human health risks for workers who
might contact panicles released from slag at the Murray Smelter Superrund Site in Murray, Utah
due to weathering processes, prior to completion of final remediation activities at the she within
the next 5 to 10 years (Laveile 1997) This technical memorandum addresses the possibility that
such risks might differ from those previously assessed by EPA in the baseline human health risk
assessment for the site (Weston 1997)
The baseline risk assessment noted that there are extensive areas of the site where slag is exposed
at the surface, but concluded that on-facility workers were unlikely to spend much time in areas
of exposed slag. The only human receptors for whom slag exposure was determined to be of
potential concern were teenagers who might spend time near the slag piles up to 50 times per
year for 7 years. These teenagers were assumed to ingest 100 mg of slag at each visit. The
fraction of lead and arsenic assumed to be absorbed from the slag was based on studies
conducted using fine particles collected from the slag piles. The risk assessment concluded that
these teenagers were unlikely to be at risk of adverse health effects from lead in the slag, and that
incremental cancer risks associated with arsenic in the slag were within EPA's acceptable risk
range (i.e., between 1 x 10* and 1 x 10"*)
There are a number of reasons why continued weathering of the slag piles during an interim
period prior to implementation of remedial actions is not likely to pose unacceptable human
health risks. The purpose of the baseline risk assessment was to assess potential risks to workers
and residents if no remedial actions were ever taken at the site. Consequently, risks from an
interim period prior to implementing remedial action cannot exceed those evaluated and judged
to be low in the baseline risk assessment unless there is some marked change in the nature of
exposures to slag, or in the nature of releases of metals from slag that was not foreseen in the
baseline risk assessment. The nature of exposures to slag is not expected to change for on-
faciliry workers or for residents. Similarly, the nature of releases of metals from slag is also
uniikeiv to chanee for reasons described below.
-------
One mechanism for release of me:ais is by weathenng,and breakdown of chunks of slag into fine
panicles. In many areas of the site, slag that has been at the surface for 50 to 100 years doesn't
show any marked signs of weathering. In areas where, weathering may have occurred, the risk
assessment already accounted for this process by assuming rr>at the ingested slag was in fine
particles that might adhere to hands poor to ingesnon. Additionally, the bioavailability of fine
panicles collected from the siag piies was tested, and the results were used in the risk assessment.
Consequently, the baseline nsk assessment is already based on weathered material, and continued
weathering is not likely to lead to increased risks. Indeed, as discussed below, further weathering
may serve to reduce the risks by changing the arsenic and lead to less bioavailable forms.
To assess the risk posed by the exposed siag at the Murray site, the risk assessment used the
bioavailability estimate for the composite Murray slag sample tested in the EPA swine study
(Weston 1997). Greater than 70 percent of the lead mass in this sample (as determined' by
electron microprobe analysis) was associated with the highly bioavailable lead form, lead oxide
(Figure 1). However, as the lead oxide weathers, it will form secondary weathering products
including lead phosphate, iron-lead oxides, and iron-lead suifates (Davis et aL 1993). Because
these weathering products will have lower solubility than the lead oxide mineral upon which the
risk assessment was -based, the nsk posed by the exposed slag will Himinith as the lead oxide
weathers and forms these secondary minerals.
While no information was presented in the risk assessment describing the arsenic mineralogy of
the Murray slag sample, Dr John Drexier of the University of Colorado has indicated that a large
fraction of the arsenic was associated with the arsenic oxide phase (Drexier 1997). Assuming
this is the case, then arsenic bioavailability would also difnjniyh with time because the arsenic
bound in soluble arsenic oxide will eventually repartition into iron oxide phases (PTI 1996),
which have a lower bioavailability than arsenic oxide.
In conclusion, it appears that the evaluation of potential human health risks from exposure to slag
in the baseline risk assessment for the Murray Smelter Superiund site was sufficiently
comprehensive to ensure that no unforeseen risks will occur during an interim period prior to
comoietion of remedial actions at the site.
-------
References
Davis, A., J.W. Drexier, M \' Ruby. A Nicholson 1993. Micromineraiogy of mine wastes in
relation to lead bioavailabiiiry. Butte. Montana. Environ. Sci. and Tech. (27) 1415-25.
Drexier, J.W. 1997. Persona] communication between J.W. Drexier, University of Colorado and
Christopher Sellstone, PTT Environmental Services.
Lavelle, B. 1997. Personal ccmmurucanon between B. Lavelle, U.S. Environmental Protection
Agency, Region VTH, Denver. CO and R Schoof, PTI Environmental Services, Bellevue, WA.
PTI. 1996. Appendix 0 - Electron Microprobe Analysis Results. Included in: Draft Site
Characterization Report for the Former Murray Smelter Site.
Weston. 1997. Baseline Human Health Risk Assessment for the Murray Smelter Superfund
Site. Prepared by Roy F Weston. Inc.. Lakewood, CO. Prepared for U.S. Environmental
Protection Agency, Region MIL Denver. CO.
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APPENDIX B
-------
TECHNICAL MEMORANDUM
DERIVATION OF PRGS FOR ARSENIC AND LEAD IN SOIL
AT THE MURRAY SMELTER SITE
1.0 INTRODUCTION
This document describes the calculation of human-heaith-based Preliminary Remediation Goals
(PRGs) for arsenic and lead in soil at the Murray Smelter site in Murray City, Utah. PRO
values were calculated for these chemicals based on the findings of the Baseline Human Health
Risk Assessment for the Murray Smelter Superfund Site (WESTON, 1997), which indicated that
concentrations of these chemicals in soil could be of concern to humans in some locations.
Health-based PRGs are site-, medium-, and chemical-specific concentration values such that the
health risk to exposed humans does not exceed some specified upper limit. For noncancer risks,
this target is usually a Hazard Quotient iHQ) of one (lE-fOO). For cancer risks, PRGs are
usually calculated for a range of possible targets (usually 1E-04, IE-OS and 1E-06). Health-
based PRGs do not usually take additivuy of risks across different chemicals or across different
media into account. However, as discussed In the Baseline Human Health Risk Assessment
(WESTON, 1997), additivity is not believed to be of concern at this site for either cancer or
noncancer effects. PRGs also do not consider the cost or feasibility of achieving the PRGs.
These factors are considered in the evaluation of potential removal actions and/or remedial
alternatives.
2.0 PRGs FOR ARSENIC
2.1 Basic Equations
PRGs for arsenic in soil were calculated using the basic approach described in USEPA RAGS
Pan B (EPA. 1991d). As detailed in the Baseline Human Health Risk Assessment (WESTON,
1997), the basic equations for estimating noncancer and cancer risk from ingestion of soil and
dust are as follows:
Noncancer Risk
ffl = (C, • cHIF, • RBA, - Cd • cfflF, • RBAJ/oRfD
Cancer Risk
Risk = (C,-1HIF,-RBA, - Ca-lHEvRBAJ-oSF
where:
C = concentration (mg/kg) of arsenic in soil (C,) or dust (CJ
Mumr Smter • Tcctmeti H—r—-"*— 1 Aprt 1977
p:\bnmauMnruaMndetpTntpil-wca.wiiS OOt 4JOO-90-ANXU
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cHIF = chronic human intake factor (kg/k'g-day) for soil (cHIF,) or dust
IHIF = lifetime human intake factor (kg/kg-day) for soil (IHEFJ or dust (1HZFJ
RBA = Relative bioavailability of arsenic in soil (RBAJ or dust (RBAJ
oRfD = Oral reference dose for arsenic (mg/kg-day)
oSF = Oral slope factor for arsenic (rag/kg-day/1
As discussed in USEPA (1995a), the contribution of arsenic in soil to the concentration of
arsenic in indoor dust can be described by an equation of the form:
Cd = ko + k^-C,
where:
Cd = concentration in dust (ppm)
ko = contribution to indoor dust from non-yard soil sources (ppm)
k,,, = mass fraction of yard soil in indoor dust (unitless)
C, = Concentration in yard soil (ppm)
Because the concentration ko is not due to site-specific sources, it is usually ignored when
calculating PRG values. Thus, the following equation is used:
C, = k^-C,
Substituting this expression into the equation above and solving for the value of C, which
corresponds to a Hazard Index of lE-rOO or a specified cancer target risk (1E-04 to 1E-06)
yields the following:
PRG,,, = oRfD/[cHIF, • RBA, - k* • cHIF,, •
FRGe = (Target Risk)/[(IHIF, • RBA, + k* • lHIFd • RBAJ • oSF]
The overall PRG for soil is then the more stringent (lower) of these two values:
PRG = minimum(PRGn., PRG.)
In the case of residents or workers exposed to arsenic in soil and dust, screening level
calculations show that PRGs based on cancer risks of 1E-04 or lower are always more stringent
than those based on an HQ of lE-i-00. Therefore, all PRG calculations shown below for arsenic
are based on cancer risk.
Mamr Sneocr - Tcttaic4 Manama.. 2 Apnl 1997
dc\jiTiyri «»»t.wpi DOi 430O.9O-ANXU
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2.2 Input Values
The Baseline Human Health Risk Assessment (WESTON, 1997) presents and explains all of the
exposure factors needed to evaluate the equation above for residents and workers, including both
"contact-intensive" (Q) workers and "non-contact intensive" (NCI) workers. Most of the factors
are standard defaults recommended by EPA (EPA. 1991a). Table 2-1 summarizes these standard
input assumptions. Values for u hich there are site-specific data are discussed below.
As described in the Baseline Human Health Risk Assessment (WESTON, 1997), paired soil-dust
samples were collected from 22 off-facility locations, and these data were used to analyze the
average relationship between levels of metals in soil and in dust. The parameters of the best-fit
linear regression through the data arc listed below:
k,, = 16ppm
k«, = 0.17 ppm per ppm
However, as discussed in EPA (!995ai. analysis of soil/dust relationships by linear regression
is complicated by the problem of measurement error, which tends to lead to an underestimate
of slope. On this basis, the best-fit slope (0.17 ppm per ppm) was rounded upwards to yield the
following approximation of k^:
k* = 0.2 ppm per ppm
RBA Adjustment
At this site, the RBA of arsenic has been evaluated for a composite sample of surface soil. This
sample was fed to young swine for 15 days, and the amount of arsenic excreted in the urine of
animals exposed to soil was compared to that for animals exposed to a soluble reference material
(sodium arsenate). Preliminary results indicate that the RBA of arsenic in the soil samples is
26%, with a 90% confidence interval from 21% to 33% (Weis et. al 1996). Although
preliminary, this value (RBA = 0.26) was employed in the Baseline Human Health Risk
Assessment (WESTON, 1997), and was also used in the calculation of the PRG for arsenic in
soil.
2.3 Results
Based on the default exposure parameters shown in Table 2-1 and the site-specific factors
discussed above, the PRG values for arsenic in soil for residential and commercial/industrial land
use are as follows:
Mwnr Sacter - Tcctaal Mm limn 3 Apnl 1997
*.wp3 DO* 450O-9O-ANXU
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TABLE 2-1. SUMMARY OF PARAMETERS^FOR ARSENIC EVALUATION
Parameter
Soil/dust intake rate as child (me'dayi
Soil/dust inuke rate as adult (mg'dayi
Fraction of total that is dust
Relative bioavailability of arsenic in soil/dust
Body weight as child (kg)
Body weight as adult (kg)
Exposure frequency (days/yr)
Exposure duration as child (yni
Exposure duration as adult (yrs)
Averaging time for cancer (yrs)
Oral slope factor
Resident
200
100
0.5
0.26
15
70
350
6
24
70
1.5
NCI-Worker
—
50
0.5
0.26
—
70
250
—
25
70
1.5
Cl-Worker
—
240
0
0.26
—
70
250
—
25
70
1.5
MIBKV Smcfccr • Tccbuul MCOORBWB
Apfiil997
DCN 4JOO-90-AKXU
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Population
Residential
NCI-Worker
Cl-Worker
PRO for Arsenic in Soil* (ppm)
IE-04
290
1.200
180
- IE-OS
29
120
18
1E-06
2.9
12
1.8
* All values expressed to two significant figures
2.4 Uncertainty in the PRO Values
It is very important to recognize that quantitative risk calculations and PRG derivations are both
inherently uncertain due to lack of knowledge regarding a number of key parameters. These
uncertainties (discussed in Section 6 of the Baseline Human Health Risk Assessment) include
lack of knowledge regarding acruaJ human exposure rates to soil, dust and slag, uncertainty in
the extent of absorption (bioavailabiiiry) of arsenic from soil and slag, and uncertainty in the
exposure levels of arsenic that are actually likely to cause significant adverse effects.
In most cases, conservative approaches are used to fill these knowledge gaps. Therefore, the
PRG values calculated above are more likely to be low than high. Because of this, the PRG
values should not be viewed as concentrations which form a clear boundary between acceptable
and unacceptable soil levels. Rather, values below the PRG should be viewed as very likely to
be protective, with a gradually decreasing probability of protection as soil values exceed the
PRG.
3.0 EVALUATION OF LEAD
3.1 PRGs for Residents
Basic Approach
The USEPA has developed an Integrated Exposure, Uptake and Biokinetic (IEUBK) model for
evaluating the risks of lead to children (age 0-7) exposed under residential circumstances. This
model was used to calculate the concentration of lead in soil which would correspond to a 5 %
probability that a child living at a location with that concentration in soil would have a blood
lead value greater than 10 ug/dL. All input assumptions to the model were those recommended
by EPA as defaults (EPA 1994a), except for 1) the Geometric Standard Deviation (GSD), 2) the
ratio of lead in dust compared to soil. 3) the relative bioavailability of lead in soil and dust, and
4) the amount of lead ingested in the diet. The basis for each of these site-specific values is
detailed in the Baseline Human Health Risk Assessment (WESTON. 1997) and is summarized
brieflv below.
Mwnv Sorter - Tectaul Mi mi ill Bin 5 April 1997
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GSD
A study of blood lead levels in Sandy. Utah, indicate that variability between different children
can be described by an individual geometric standard deviation of 1.4 (EPA 1995b). Because
the population of Sandy is believed to be generally similar to the population of Murray, this
value (a GSD of 1.4) is considered to be more relevant and a better approximation of the true
site-specific value than the default value (1.6), so the site-specific value is used in place of the
default value.
Soil/Dust Relationship
The normal assumption used in the EEUBK model is that the concentration of lead in indoor dust
is 70% of that in outdoor soil (EPA 1994a). However, this assumption has been found to
overestimate lead concentrations in dust at some mining-related sites. As described in the
Baseline Human Health Risk Assessment (WESTON 1997), paired soil-dust samples were
collected from 22 off-facility locations, and these data were used to analyze the average
relationship between levels of lead in soil and in dust. The slope of the best-fit straight line
through the d«*a ra|rqiiat«ri by linear regression is 0.32 ppm per ppm. However, as noted
above, analysis of soil/dust relationships by linear regression is complicated by the problem of
measurement error, which tends to lead to an underestimate of slope and an overestimate of
intercept. On this basis, the best-fit slope was rounded upwards to 0.35 ppm per ppm, and this
value was used in place of the default of 0.70 in the EEUBK model.
RBA
The EEUBK model employs a default relative bioavailability factor of 60% for lead absorption
from soil and dust (compared to that for water or food) (EPA 1994a). However, there are
several studies which provide evidence that lead in soil from mining/ smelting sites may be
absorbed less -extensively than this default. The EPA has conducted a study of the bioavailability
of lead in a composite soil sample from the Murray Smelter site (EPA 1996a). Preliminary
results are summarized below:
RBA in Site Soil
Plmsible Range
Preferred Range
Suggested Point Estimate
Value
0.67-0.84
0.67-0.75
0.71
As seen, although there is uncertainty in the estimate, the relative bioavailability for soil is
probably about 70%, slightly higher than the default value used in the EEUBK model. Based
on this value, and aiming that lead in food and water is about 50% absorbed by children (EPA
1990), this RBA value corresponds to an absolute bioavailability of 35% (0.35).
DQf 4500-9O-ANXU
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Dietary Lead Intake
As discussed in Appendix A. recent dietary data collected by the FDA support the view that
dietary intakes are now lower than the default value t provided in the IELJBK model. The
revised values are as shown beiow. and these were used in the calculation of the soil lead PRG
for residential land use.
Aee
6-1 I months
1 vear
1 years
3 vears
•1 vears
5 years
6 vears
Intake fug/day)
1.82
1.90
1.87
1.80
1.73
1.83
2.02
Results
Using the inputs discussed above, the IEUBK model was used to find the concentration of lead
in soil which corresponded to a 5 % nsk of exceeding a blood lead value of 10 ug/dL in children
age 0-84 months. The resulting value (the PRG for lead in soil) is about 630 ppm.
It is important to realize that this point estimate of the soil PRG for lead in residential areas is
uncertain and that a range of other PRG values are plausible, depending which combination of
input parameters are assumed to be most appropriate for the site. Appendix B presents a
discussion of this uncertainty in the residential PRG, and indicates that values in the range of
600-1,200 ppm are plausible.
3.2 PRGs for Workers
Because thr EPA EEUBK model was developed to evaluate young children exposed under long-
term residential conditions (EPA 1994a), this model is not suitable for estimating PRG values
for workers. There are several methods which have been proposed for evaluating lead exposure
in adults, including models developed by Bowers et al. (1994), O'Flaherty (1993), and the State
of California (CEPA 1992). Of these, the model of Bowers et al. is most nearly consistent widi
the approach employed in the EEUBK model, and is the EPA-recommended interim approach
for evaluating leads exposures in adults (EPA 1996b).
Basic Equation
The Bowers model predicts a geometric mean blood lead level (PbBGM) by summing the
"baseline" geometric mean blood lead level (PbBGM0) (that which would occur in the absence
of any occupation exposures to soil or dust) with the increment in blood lead that is expected
as a result of occupational exposure to soil or dust. The latter is estimated by multiplying the
Apnl 1997
OOt 4JOO-90-ANXU
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absorbed dose of lead from occupational soil/dust exposures by a "biokinetic slope factor"
(BKSF). Thus, the basic equation is:
PbBGM = PbBCM0 - BKSF • (C, IR, • AF, -r Cd • IR« • AFJ
where:
PbBGM = Geometric mean blood lead level (ug/dL) in a population of adults exposed
to lead-contaminated sod/dust via occupational activities
PbBQM0 = Geometric mean blood lead level in adults not exposed to lead-
contaminated soil/dust via occupational activities
BKSF = Biokinetic slope factor (ug/dL. increase in blood lead per ug/day lead
absorbed)
C = Arithmetic mean concentration (ug/'g) of lead in soil (C,) or dust (C,,) at
the workplace
IR = Mean daily intake rate of soil (IRJ or dust (IRJ at the workplace (g/day)
AF = Absolute absorption fraction (bioavailability) of lead in soil (AFJ or in
dust(AF
-------
TABLE 3-1. SUMMARY OF MODEL PARAMETERS FOR EVALUATION OF
LEAD RISKS TO ADULT WORKERS
Model Parameter
95th Percentile PbB in fetus (ue/dL)
Mean ratio of fetaJ to maternaj PbB
Individual geometric standard d:vianon iGSDl
Bav.iinf! blood lead value (PbBCM (ug'dU
Biokinetic slope factor (BKSF) (ug'dL per uc'day)
Soil and dust ingestion rate (TR^ (g'davi
Fraction of total that is soil
Fraction of total that is dust
Ratio of concentration in dust to that in soil iK^J
Exposure frequency (daya/yr)
Oral absorption fraction for lead in soil/dust
NCI-Workers
10
0.9
1.54
2.3
0.4
0.50
0.5
0.5
0.35
219
0.07
Cl-Workers
10
0.9
1.54
2.3
0.4
0.240
1.0
0
—
185
0.07
Murrrr Si
p:\IWB
-Ti
uwpi
Apnl 1997
DCM 4500-90-ANXU
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The EPA has not yet issued formal guidance on the blood lead level that is considered
appropriate for protecting the health of adults. However, both EPA and the Center for Disease
Control (CDC) recommend that there should be no more than a 5 % likelihood that a young child
should have a PbB value greater than 10 ug/dL (CDC 1991, EPA I994c). Since exposed
workers could include pregnant women, and because the fetus is exposed to lead levels nearly
equal to those of the mother, the health criterion selected for use in this evaluation is that there
should be no more than a 5 % chance that the fetus of a pregnant woman would have a PbB
above 10 ug/dL.
This health goal is equivalent to specifying that the 95th percemile of the PbB distribution in
fetuses does not exceed 10 ug/dL:
PbB,jfetal £ 10 ug/dL
The relationship between fetal and maternal blood lead concentration has been investigated in
a number of studies. Goyer (1990) reviewed a number of these studies, and concluded that there
was no significant placental/fetaJ barrier for lead, with fetal blood lead values being equal to or
just slightly less than maternal blood lead values. The mean ratio of fetal PbB to maternal PbB
in three recent studies cited by Cover was 0.90. Based on this, the 95th percentile PbB in the
mother is then:
PbB^maternai = 10/0.90 = 11.1 ug/dL.
Fixing 11.1 ug/dL as the upper 95th percentile of the blood lead distribution in exposed women,
the geometric mean blood lead value is derived from the following equation:
I.64J
= 11.1/GSD,
The GSDj in this equation is intended to describe the individual variability between different
people in the amount of environmental media which they ingest, in the fraction of the lead which
they absorb from those media, and in the increment which that absorbed lead causes on their
average PbB value. Normally, vaJues of GSD, are estimated from observed distributions of PbB
values in a population. The observed GSD from the population is referred to as GSDP. The
relationship between GSDP and GSD, is usually difficult to resolve. Conceptually, a GSDP value
reflects variability of two main types: 1) variability in individual activity patterns and
toxicokinetic factors, and 2) variability in the concentrations of lead in environmental media.
The first component is equal to GSD,. Thus, the empirical GSDP represents an upper bound on
the value of GSDj.
Data collected during the NHANES lH survey indicate that the GSDP for all women is about 2.1
(Pirkle et al. 1994). Data collected during a study of the residents of Sandy, Utah (EPA 1995b)
indicates the GSDP for blood lead levels in adult women was 1.54. Because the residents of
Sandy are likely to be more similar to the residents of Murray that the general population of the
US, the GSDp value of 1.54 from Sandy was assumed to apply at the Murray site. In order to
10 Apfii 19*7
PQ, 4JOMO-ANXU
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be conservative, the value of GSD, was taken to be e^ual to GSD,,. That is, a GSD value of
1.54 was used to estimate the full distribution of blood-lead values in the exposed population.
Based on this value, the target geometric mean PbB forjhe woman of child-bearing age is 5.46
ug/dL.
Results
Based on the parameters summarized in Table 3-1, the levels of lead in soil that will be
protective for adult on-site workers are:
Population
NCI-Workers
Cl-Workers
PRG for Lead (ppm)
5600
930
33 Uncertainty in the PRG values
As discussed above, it is important to stress that there is substantial uncertainty in the soil lead
PRG values calculated for both residential children and for on-site workers. These uncertainties
are related to lack of knowledge regarding true soil and dust intake rates, lack of certainty in
the true absorption fraction for lead, and uncertainty in the true level of health risk posed by low
level lead exposures to children and fetuses. In addition, there is uncertainty associated with the
accuracy of the mathematical models used to make the calculations (the EEUBK model and the
Bowers model). These "model uncertainties" arise because human exposure, absorption,
distribution and clearance of lead are very complicated and dynamic processes, and any
mathematical model which seeks to quantify the processes must always be an over-simplification.
In addition, many of the pharmacokinetic parameters relating to lead metabolism in humans are
difficult to study and measure, so there is uncertainty whether the values used in the models are
accurate. Because of these uncertainties, the PRG values calculated for lead should not be
thought of as a clear boundary between acceptable and unacceptable soil levels. Rather, values
below the PRG should be viewed as very Likely to be protective, with a gradually decreasing
probability of protection as values exceed the PRG.
Mumr Stacker - Te
f.M
11
Aprt 1997
DO* 4iOO.9O.ANXU
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4.0 REFERENCES
Bowers TS, Beck BD, Karam HS. 1994. Assessing the Relationship Between Environmental
Lead Concentrations and Adult Blood Lead Levels. Risk Analysis 14:183-189.
CDC. 1991. Preventing Lead Poisoning in Young Children. US Department of Health and
Human Services, Centers for Disease Control.
CEP A. 1992. California Environmental Protection Agency, Department of Toxic Substances
Control. Supplemental Guidance for Human Health Multimedia Risk Assessment of Hazardous
Waste Sites and Permitted Facilities. Sacramento, California.
EPA. 1990. U.S. Environmental Protection Agency, Technical Support Document on I gad.
ECAO-CIN-757. Cincinnati, OH: EPA Office of Environmental Criteria and Assessment
Office. September.
EPA. 199 la. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency
Response. Human Health Evaluation Manual, Supplemental Guidance: "Standard Default
Exposure Factors". Washington. D.C. OSWER Directive 9285.6-03.
EPA. 1991b. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency
Response. Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions.
Washington, D.C. OSWER Directive 9355.0-30.
EPA. 199Id. U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response. Risk Assessment Guidance for Superfund. Volume I. Human Health Evaluation
Manual (Pan B, Development of Risk-Based Preliminary Remediation Goals). EPA Document
EPA/540/R-92/003.
EPA. 1994a. U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response. Guidance Manual for the Integrated Exposure Uptake Biokineric Model for Lead in
Children. EPA Publication No. 9285.7-15-1.
EPA. 1994b. U.S. Environmental Protection Agency, Technical Review Workgroup for Lead-
Comments and Recommendations on a Methodology for Estimating Risk Associated with Acute
Lead Exposures at Superfund Sites.
EPA. I994c. Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective
Action Facilities. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency
Response. Memorandum from Elliot P. Laws. Assistant Administrator. July 14, 1994.
EPA. 1995a. U.S. Environmental Protection Agency, Region 8 Superfund Technical Section.
Standard Operating Procedure. Evaluating Exposure from Indoor Dust.
Many "inailer • Tccfencd llminr»»«i 12 April 1997
S DO* 43004O-ANXU
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EPA. 1993b. U.S. Environmental Protection Agency,'TRegion 8 Superfund Technical Section.
Evaluation of the Risk from Lead and Arsenic. Sandy^Smelter Site, Sandy, Utah.
EPA. 1996a. U.S. Environmental Protection Agency,-JRegion 8 Superfund Technical Section.
Unavailability of Lead in Soil and Slag from the Murray Smelter Superfund Site.
EPA. 1996b. Recommendations of the Technical Review Workgroup for Lead for an Interim
Approach to Assessing Risks Associated with Adult Exposures to Lead. U.S. Environmental
Protection Agency, Technical Review Workgroup for Lead. December, 1996.
Goyer RA. 1990. TransplacentaJ Transport of Lead. Environ. Health Perspect. 89:101-105.
O'Flaherty EJ. 1993. Physiological]y Based Models for Bone-Seeking Elements. IV. Kinetics
of Lead Disposition in Humans. Toxjcol. Appl. Pharmacol. 118:16-29.
Pirkle JL, Brody DJ, Gunter EW. Kramer RA. Paschal DC, Flegal KM, Matte TD,. 1994. The
Decline in Blood Lead Levels m the United States. The National Health and Nutrition
Examination Surveys. JAMA 272:284-291.
Weis, CP, Henningsen G, Griffin S. 1996. Preliminary Bioavailabiliry Values for Arsenic in
Soil and Slag from the Murray Smelter Superfund Site. Memo from Christopher P. Weis, Gerry
Henningsen and Susan Griffin to Bonnie Lavelle, Hat<»H 8/19/96.
Roy F. Weston, Inc. (WESTON). 1997. Baseline Human Health Risk Assessment for the
Murray Smelter Superfund Site. Report prepared by Roy F. Weston, Inc. for the USEPA
Region Vm. April, 1997.
Murm Sorter - Tccfeoiui Mwonodun 13 Aprt 1997
DO* 4900-90-ANXU
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APPENDIX A
REVISION OF DIETARY LEAD INTAKES
IN EEUBK MODEL
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MEMORANDUM
TO: Bonnie Lavelle
ppTpfriia] Project Manager
Murray Smelter Site
FROM: Susan Griffin. PhD. DABT
Regional Toxicologist
Program Suppon Group
SUBJECT: Revision of Dietary Lead Intakes in IEUBK Model
This memorandum is in response to ASARCO's request to update the dietary lead intake
default values in the IEUBK Model for the Murray Smelter Site. As you are aware, the IEUBK
dietary lead intake values are based on FDA Total Diet Study data from 1986 to 1988. A
number of scientific papers have been published recently by Dr. Ellis Gunderson (Gunderson,
1995) and Dr. Michael Bolger (Bolger et al. 1996) of the U.S. FDA which contain more recent
information from the FDA's Total Diet Studies. These papers list the mean daily intake of lead
from the diet for the years from 1986-1991.
I spoke with Dr. Rob FJias of the USEPA who was responsible for the dietary lead intake
component of the IEUBK model. He indicated it would be appropriate to use the more recent
FDA data to update the dietary input values in the IEUBK model. As you may note from the
FDA papers, dietary intakes are provided for children 6-11 months of age and 2 years of age.
The next age group studied are teenagers 14-16 years of age. The IEUBK model contains age-
adjusted dietary lead intakes for each year up to 7 years of age. This is because the age groups
other than 6 months and 2 years were extrapolated. Originally, Dr. Efli^t did this by using the
information from the FDA Total Diet Studies of 1986-1988 and the data from the Pennirigton
studies of 1975 on food consumption rates for each age group. ASARCO is proposing to
perform this extrapolation by a simpler ratio method between the older IEUBK model values and
the more recent FDA data. Dr. Hlias indicated that this was a satisfactory method and would
probably not yield significantly different results from the more complicated method of combining
the FDA data with food consumption rate data. Dr. Efog did indicate that he will be uprising
the dietary intake component of the IEUBK model in the near future. Those values may be
slightly different from those proposed here, because he will be combining the most recent FDA
data with a new 1996 study on food consumption rates in the U.S. which is just coming out.
Using the more recent FDA data to update the IEUBK model values results in the following
intakes:
Mmr Softer- T«eta«lM—«*• A-l Aped 1997
DOMSOMOANXU
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Age Dietary T^arf Tmake fug/day)
6-11 raos 1.82
1 year" 1.90
2 years 1.87
3 years- 1.80
4 yean* 1.73
5 years* 1.83
6 years * 2.02
"Derived from IEUBK 99d value for 1 year divided by the ratio of the IEUBK 99d value for
6 months/ 1990-91 FDA data for 6 months
-Derived from IEUBK 99d value for ihat age divided by the ratio of the EEUBK 99d value for
2 years/1990-91 FDA data for 2 years
When these more recent values are input to the IEUBK model the current PRG range of 550
-1100 ppm will be changed to 630-1260 ppm.
References
Bolger, PM, Yess, NJ, Gunderson. EL, Troxell, TC and Carrington, CD. 1996. Identification
and Reduction of Sources of Dietary Lead in the United States. Food Additives and
Contaminants. VoL 13, No 1, 53-60.
Gunderson EL. 1995. FDA Total Diet Study, July 1986-April 1991, Dietary Intakes of
Pesticides, Selected Elements, and Other Chemicals. Journal of AOAC International Vol. 78,
No. 6, 1353-1363.
Mumv Saeftcr - Tccboal M«enD*a A-2 Apr* 1997
p:VbnBBpr>-ucix.wpj DO! 4JOO-9O-ANXU
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.APPENDIX B
PRELIMINARY REMEDIATION GOALS
FOR THE MURRAY SMELTER SITE
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MEMORANDUM
TO: Bonnie Lavelle
RPM, Murray Smelter Site
FROM: Susan Griffin, PhD. DABT
Regional lexicologist
SUBJECT: Preliminary Remediation Goals for the Murray Smelter Site
Development of risk-based preliminary remediation goals (PRGs) are pan of the risk
assessment process. The first step involves a baseline risk assessment which uses contaminant
concentrations and exposure variables in conjunction with toxiciry criteria, to estimate exposure
and risk for a defined population at a site. At lead sites, a risk assessment is conducted by
inputting contaminant concentrations into a simulation model, the Integrated Exposure Uptake
Biokdnetic (IEUBK) Model, which predicts blood lead levels in children 6 months to 7 yeazs
of age. If greater than 5 % of those blood lead levels exceed 10 ug/dl, the risk is considered to
be unacceptable. Risk-based PRG calculations are basically the reverse of the risk assessment
calculations. These calculations use a selected acceptable risk (e.g., no more than 5% > 10
ug/dl) and exposure variables to estimate a desired contaminant concentration.
A single PRG could be estimated for the site using the IEUBK model with single values for
both default and site-specific parameters. Using the data from the 1996 Baseline Risk
Assessment for the Murray Smelter Superfund Site, (e.g., IEUBK model default values except
for a site-specific Geometric Standard Deviation of 1.4, a soil/dust correlation coefficient of
0.35, and a soil/dust bioavailabiliry of 35 %) this single PRG would be 550 ppm. However, we
know there is variability and uncertainty in both analytical measurements (e.g., bioavailability
estimates, soil concentration, etc.), as well as population behavior and exposure. For example,
all children do not ingest the exact same amount of soil, or spend 100% of their time in one
location. Concentrations of lead in house dust are not identical for each home. These are
examples of variability. Use of randomly collected soil samples to predict the true value of lead
concentrations in the soil is an example of uncertainty. Therefore, development of PRG's which
attempt to capture this uncertainty and variability convey more information about risk at a site,
than a single PRG estimate.
EPA-Region 8 is currently in the process of quantitating this uncertainty in the risk estimate
and PRG estimate for the Murray Smelter Site via a Monte Carlo analysis. This is a complex
process, however, and will not be completed until late Spring 1997. In the interim, a more
simplified approach may be useful. This approach looks at the variability around the estimate
of the mean values which are used as inputs to the EEUBK model. As you are aware, the default
inputs to the IEUBK model represent average or typical values for intake and uptake. Rather
than evaluate aj] of the DEUBK model inputs, it is more efficacious to evaluate those which most
significantly affect the outcome. At the Murray Smelter Site the lead in soil and house dust are
the most significant sources of exposure. From this exposure pathway, the variables which
impact soil and dust exposure the most are (1) bioavailabiliry, (2) the correlation between lead
Mumr Sowttcr • Technical Mamarmtaam A-l Apni 1997
iaevT*Vt'<*cb-wP3 DCN 430O-9O-ANXU
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in soil and'house dust, and (3) soil ingestion rate. Babied on site-specific data from the swine
bioavailabiiity study and the paired soli and dust concentrations, the variability around the mean
estimates for (1) and (2) are fairly small. This variability would result in PRG's which ranged
from 500 - 640 ppm. However, based on information from technical documents for the National
Ambient Air Quality Standard (NAAQS) for lead, the Guidance Manual for the IEUBK Model
and information from the Anaconda Childhood soil ingestion study, the variability surrounding
the mean estimate for soil ingestion is fairly significant. At the Murray Smelter site it results
in a range of PRGs from 550 -1100 ppm for lead in soil. As you are aware, the IEUBK model
was utilized originally by tbe Office of Air Quality Planning and Standards (OAQPS) for the
development of the lead NAAQS. Rather than utilizing a single value for soil ingestion, the
model employed a range of average estimates. As pan of the technical documentation of the
NAAQS, these were reviewed and approved by the EPA's Science Advisory Board. These
ranges are documented in the 1989 OAQPS report, "Review of the National Ambient Air
Quality Standards for Lead: Exposure Analysis Methodology and Validation" and the 1994
Guidance Manual for the IEUBK Model for Lead in Children. It wasn't until the modification
of the IEUBK model by the Superfund program, that the maximum value in that range was
selected as the single soil ingestion input for the IEUBK model. In addition a recent soil
ingestion study conducted by Dr. Edward Calabrese from the University of Massachusetts for
children at the Anaconda Smelter site, yielded similar estimates of variability around a mean soil
ingestion rate. The four best tracers resulted in average estimates ranging from 89 - 126 mg/day
with upper and lower 95% confidence limits around the averages ranging from 15 to 218
mg/day.
In summary, the quantitaiion of variability surrounding the mean soil ingestion rate is
based on technically sound scientific data. Tbe precedence for it's use is the development of the
NAAQS for lead. In addition, various points along the range have also been used on a site-
specific basis at both the Leadville and Butte NPL sites. By using a range of PRGs which take
into account the variability in mean soil ingestion rates, more realistic information is conveyed
about the variability surrounding lead exposure and risk from soil and dust . The range does
not imply that there is greater risk at the high end of the range, and less risk at the low end of
the ranee. THCTMH it suggests that any point on the range can represent EPA's risk goal of no
greater than 5% exceedance of 10 ug/dl.
At Murray, the PRPs have suggested thai the 1988 dietary default values of the model be
updated and that an in vitro bioavailabiiity study be conducted. In terms of how these new data
may affect the PRG range of 550 - 1100 ppm, the update dietary information will provide only
a small impact. The new range will be 600 - 1200 ppm. Depending on the results of the in
viiro study, the change could range from minima] to significant. Changes in bioavailabiiity are
linear with changes in PRG estimates, provided soil lead is the only or major source of
exposure. For example a reduction in bioavailabiiity from 30% to 15% will result in a doubling
of the PRG estimate.
Many Smctta - TcctanJ MimnrwiOm A-2 • Apnl 1997
p:ptTH|in m U.wp5 DCN 4JOO-9O-ANXU
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APPENDIX C
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
999 18th STREET-SUITE BOO
DEMVER. COLORADO 80202-2466
MEMORANDUM
DATE: Novembers, 1997
FROM: Rich Muza, 8EPR-EP
TO: Bonnie Lavelle, 8EPR-SR
SUBJECT: Preliminary Determinations of Alternate Concentration Limits (ACLs) for
Arsenic in Ground Water at the Murray Smelter Site, Murray, Utah
As per your request, I have taken a preliminary look at the determination of ACLs
for arsenic in ground water at the Murray Smelter Site. I have focused my effort on arsenic
as this analyte is the driver for any risk determinations from the ground-water pathway at
the Site. ACLs for other analytes can easily be determined based on this work for arsenic.
I will provide a discussion of the concepts utilized in this ACL determination and
then provide the prelimary ACL results based on various scenarios.
ALTERNATE CONCENTRATION LIMITS AS APPLIED TO THE SITE
Ground water at various locations on the Murray Smelter Site is contaminated with
arsenic at ppm-levels. There are potentially three distinct plumes which have migrated a
relatively short distance downgradient of the source areas. These plumes show zones of
high arsenic concentrations with a significant drop-off in most cases to background levels
over a relatively short distance. The plumes are present in the water-table aquifer of the
terrace and fill deposits near Little Cottonwood Creek as well as within the floodplain
deposits of the Creek. The ultimate fate of the arsenic-contaminated ground water is
discharge to Little Cottonwood Creek.
Historically, impacts to the Creek from Site-specific contamination have been
present. Monitoring over time has shown levels of arsenic approaching and exceeding the
ambient water quality criteria (AWQC) of 190 ppb. However, recent studies have shown
that this surface-water contamination can be attributed to discharges from a drainage
conduit that is present at the State Street bridge. This conduit has been found to run
southward along State Street and to have an arm that runs through the Site in the area of
the former Baghouse where one of the arsenic plumes is present. Therefore, the
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mechanism for measurable contaminant migration to Little Cottonwood Creek looks to be
ground-water seepage from the Baghouse plume into the drainage conduit with rapid
tranport to its discharge point at the State Street bridge.
SARA allows for the setting of ACLs for contaminants where "1) there are known
and projected points of entry of such ground water into surface water, 2) on the basis of
measurements or projections, there is or will be no statistically significant increase of such
constituents from such ground water in such surface water at the point of entry or at any
point where there is reason to believe accumulation of constituents may occur
downstream, and 3) the remedial action includes enforceable measures that will preclude
human exposure to the contaminated ground water at any point between the facility
boundary and all known and projected points of entry of such ground water into surface
water". Since the impacts to Little Cottonwood Creek are presently believed to be
attributable to the drainage conduit pathway, ACLs are applicable at the Site. However,
it is recommended that a contingency plan be developed in the event that remedial actions
to stop contaminant migration in the drainage conduit do not result in significant reductions
in contaminant concentrations in Little Cottonwood Creek.
ACLs at the Site will then be developed for the protection of surface-water quality
in Little Cottonwood Creek. The AWQC of 190 ppb will be applied to this determination.
The logic behind this determination is to assure that arsenic-contaminated ground water
upon discharge to Little Cottonwood Creek will be diluted by streamflow such that the
AWQC is never exceeded in the Creek. The determination is simply a mass balance
calculation based on theoretical ground-water and surface-water flow conditions.
If this ACL approach is accepted as the remedial action for contaminated ground
water at the Site, then the point of compliance for maintanence of the ACL is within the
water-table aquifer adjacent to Little Cottonwood Creek. That is a line of monitoring wells
completed within the water-table aquifer will have to be installed on the floodplain along
the Creek and be routinely monitored for the contaminants of concern.
PRELIMINARY ALTERNATE CONCENTRATION LIMIT DETERMINATION FOR THE SITE
I have looked at a number of hydrologic scenarios — all based on Site-specific data
— in this preliminary ACL determination. In all scenarios I considered the zone of
contaminated ground-water discharge potentially impacting the Creek to be the stretch
from SW-2 downstream to SW-3 or a distance of approximately 3500 feet. This
assumption is based on a combined analysis of the ground-water flow directions and
contaminant plume distributions at the Site; if both the Baghouse and Arsenic Storage Bin
plumes were to migrate to the Creek, based on the existing ground-water flow information,
their discharge and impacts to the Creek would occur between SW-2 and SW-3 . Also,
in all scenarios I have only considered ground-water discharge to the Creek from the Site
or south side as the Site-specific database focuses on this ground-water flow system; this
is a conservative assumption as based on the conceptual model for the area a component
Primed en Recycled Paper
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of ground-water flow from the north discharging to the Creek will exist. Lastly, a
background arsenic level in surface water of 0.007 ppm was used; this was the maximum
value detected in samples from SW-2 where most of the sampling results were below the
detection limit of 0.005 ppm. I will summarize each scenario and the ACL for arsenic
result.
Scenario 1
Under Scenario 1 the determinations of ground-water flow and surface-water
discharge utilized in ground-water flow and solute transport modeling for the Site
Characterization and Feasibility Study reports were input into a mass balance equation.
The values for ground-water flow from the Site to the Creek range from 0.02 to 1.92 cfs
based on this analysis. A low-flow discharge rate for Little Cottonwood Creek was
estimated based on Site-specific data to be 3.0 cfs.
Using the above values for flow conditions, the background arsenic level, and the
AWQC criteria, the ACL for arsenic under this scenario would range from 0.476 to 27.6
mg/l. (See attachment for calculations.)
Scenario 2
Under Scenario 2 determinations of ground-water flow and surface-water discharge
to be utilized were based on my assessment of the Site-specific database. Data used
included that from the Site Characterization and Feasibility Study reports as well as the
quarterly monitoring program results. The evaluation focused on ground-water flow within
the floodplain alluvium of the Creek. The hydraulic conductivity for MW-112 was used and
the hydraulic gradient was determined based on ground-water flow between MW-112 and
Well 2. The value for ground-water flow from the Site to the Creek was determined to be
0.0075 cfs based on this analysis. A low-flow discharge rate for Little Cottonwood Creek
was estimated based on Site-specific data for SW-2 to be 2.5 cfs.
Using the above values for flow conditions, the background arsenic level, and the
AWQC criteria, the ACL for arsenic under this scenario would be 61.2 mg/l. (See
attachment for calculations.)
DISCUSSION OF ALTERNATE CONCENTRATION LIMIT RESULTS
The results of this exercise are ACLs for arsenic at the Site ranging from 0.476 to
61.2 mg/l. In theory these ACLs if attained at the POC should assure that the AWQC of
190 ppb is not exceeded in Little Cottonwood Creek due to contaminated ground-water
discharge from the Site. These values are conservative in that no ground-water discharge
from north of the Site was considered in this determination.
Based on the existing database for the Site, only the lowest determined ACL (0.476
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mg/l) is exceeded in monitoring points (monitoring wells or hydropunch sample sites). The
other values exceed any detected concentrations on-Site.
These ACLs show a range of over two orders of magnitude (0.476 to 61.2 mg/l).
This range provides an indication of the levels of uncertainly in this type of determination.
As a result, it is imperative that if this ACL approach is accepted as the remedial action for
contaminated ground water at the Site, then a significant monitoring network needs to be
established within the water-table aquifer on the floodplain along the Creek. This network
will need to be routinely monitored for the contaminants of concern.
If you should have any questions, please feel free to contact me at x6595.
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Scenario 1
ACL CALCULATIONS
AWQC:
CAWQC = 0.19ppm
Background Surface-Water CBKG = 0.007 ppm
(SW-2 maximum)
Ground-Water Flow:
QGW = KiA
K = 5ft/d
i = 0.008 ft/ft
A= 43,200ft2
QGW = 0.02 cfs
(FS modeling work)
K=154ft/d
i = 0.028 ftm
A = 43,200 ft2
QGW = 1.92 cfs
Surface-Water Flow:
Qsw = 3.0 cfs
(Estimated)
ACL:
For QGW = 0.02 cfs
(3.0 cfs) X (0.007 ppm) + (0.02 cfs)QCL = (3.0 cfs +
0.02 cfs) X (0.19 ppm)
CACL = 27.6 ppm
For QGA = 1.92 cfs
(3.0 cfs) X (0.007 ppm)+ (1.92 cfs)C;CL = (3.0 cfs +
1.92 cfs) X (0.19 ppm)
CACL = 0.476 ppm
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Scenario 2
AWQC:
Background Surface-Water: CBKG = 0.007 ppm
(SW-2 maximum)
Ground-Water Flow:
QGW = KiA
K=14ft/d
i = 0.0012 ft/ft
A = 38,500 ft2
QGW = 0.0075 cfs
(MW-112 slug tests)
(1/97 ground-water flow between
MW-112 and Well-2)
(A = b X I = 11 ft X 3500 ft)
Surface-Water Flow:
ACL:
= 2.5 cfs
(Estimated)
(2.5 cfs) X (0.007 ppm) + (0.0075 cfs)CACL = (2.5 cfs +
0.0075 cfs) X (0.19 ppm)
CACL = 61.2ppm
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REOIOIH VIII
999 IBth STREET-SUITE 600
OEHVER. COLORADO 80202-2466
MEMORANDUM
DATE: February 25, 1998
FROM: Rich Muza, 8EPR-EP
TO: Bonnie Lavelle, 8EPR-SR
SUBJECT: Determination of an Alternate Concentration Limit (ACL) for Arsenic in
Ground Water at the Murray Smelter Site, Murray, Utah
As per your request, I have taken a final look at the determination of an ACL for
arsenic in ground water at the Murray Smelter Site. ACLs for other analytes can easily be
determined based on this work, if necessary.
I will not provide a thorough discussion of the concepts of the ACL determination
as this information is detailed in my memorandum on this subject to you dated November
5, 1997. I will provide the ACL results based on the various scenarios detailed in that
memo.
AN ALTERNATE CONCENTRATION LIMIT FOR ARSENIC AS APPLIED TO THE SITE
An ACL for arsenic at the Site will be developed for the protection of surface-water
quality in Little Cottonwood Creek. The Utah Agricultural Water Standard of 0.1 ppm for
arsenic will be applied to this determination. The logic behind this determination is to
assure that ground water contaminated with arsenic upon discharge to Little Cottonwood
Creek will be diluted by streamflow such that the 0.1 ppm concentration is not exceeded
in the Creek. The determination is simply a mass balance calculation based on theoretical
ground-water and surface-water flow conditions.
ALTERNATE CONCENTRATION LIMIT DETERMINATION FOR THE SITE
I have looked at a number of hydrologic scenarios — all based on Site-specific data
— in the ACL determination. In all scenarios I considered the zone of contaminated
ground-water discharge potentially impacting the Creek to be the stretch from SW-2
downstream to SW-3 or a distance of approximately 3500 feet. This assumption is based
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on a combined analysis of the ground-water flow directions and contaminant plume
distributions at the Site; if both the Baghouse and Arsenic Storage Bin plumes were to
migrate to the Creek, based on the existing ground-water flow information, their discharge
and impacts to the Creek would occur between SW-2 and SW-3 . Also, in all scenarios
I have only considered ground-water discharge to the Creek from the Site or south side
as the Site-specific database focuses on this ground-water flow system; this is a
conservative assumption as based on the conceptual model for the area a component of
ground-water flow from the north discharging to the Creek will exist. Lastly, a background
arsenic level in surface water of 0.007 ppm was used; this was the maximum value
detected in samples from SW-2 where most of the sampling results were below the
detection limit of 0.005 ppm. I will summarize each scenario and the ACL for arsenic
below.
Scenario 1
Under Scenario 1 the determinations of ground-water flow and surface-water
discharge utilized in ground-water flow and solute transport modeling for the Site
Characterization and Feasibility Study reports were input into a mass balance equation.
The values for ground-water flow from the Site to the Creek range from 0.02 to 1.92 cfs
based on this analysis. A low-flow discharge rate for Little Cottonwood Creek was
estimated based on Site-specific data to be 3.0 cfs.
Using the above values for flow conditions, the background arsenic level, and the
Agricultural Standard, the ACL for arsenic under this scenario would range from 0.245 to
14.05 mg/l. (See attachment for calculations.)
Scenario 2
Under Scenario 2 determinations of ground-water flow and surface-water discharge
to be utilized were based on my assessment of the Site-specific database. Data used
included that from the Site Characterization and Feasibility Study reports as well as the
quarterly monitoring program results. The evaluation focused on ground-water flow within
the floodplain alluvium of the Creek. The hydraulic conductivity for MW-112 was used and
the hydraulic gradient was determined based on ground-water flow between MW-112 and
Well 2. The value for ground-water flow from the Site to the Creek was determined to be
0.0075 cfs based on this analysis. A low-flow discharge rate for Little Cottonwood Creek
was estimated based on Site-specific data for SW-2 to be 2.5 cfs.
Using the above values for flow conditions, the background arsenic level, and the
Agricultural Standard, the ACL for arsenic under this scenario would be 31.1 mg/l. (See
attachment for calculations.)
DISCUSSION OF ALTERNATE CONCENTRATION LIMIT RESULTS
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The results of this exercise are ACLs for arsenic at the Site ranging from 0.245 to
31.1 mg/l. In theory these ACLs if attained at the POC should assure that the Utah
Agricultural Standard for arsenic of 0.1 ppb are not exceeded in Little Cottonwood Creek
due to contaminated ground-water discharge from the Site. These values are conservative
in that no ground-water discharge from north of the Site was considered in this
determination.
The arsenic ACLs show a range of over two orders of magnitude (0.245 to 31.1
mg/l). This range provides an indication of the levels of uncertainly in this type of
determination. As a result, it is imperative that if this ACL approach is accepted as the
remedial action for contaminated ground water at the Site, then a significant monitoring
network needs to be established within the water-table aquifer on the floodplain along the
Creek. This network will need to be routinely monitored for the contaminants of concern.
If you should have any questions, please feel free to contact me at x6595.
Printfd on RocytJed P»p*r
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ARSENIC ACL CALCULATIONS
Scenario 1
Utah Agricultural Standard:
= 0-1 PPm
Background Surface-Water:
= 0.007 ppm
(SW-2 maximum)
Ground-Water Flow:
QGW = KiA
K = 5ft/d
i = 0.008 ft/ft
A= 43,200ft2
QOW = 0.02 cfs
(FS modeling work)
K=154ft/d
i = 0.028 ft/ft
A = 43,200 ft2
0 = 1.920*5
Surface-Water Flow:
ACL:
For QGW = 0.02 cfs
= 3.0 cfs
(Estimated)
(3.0 cfs) X (0.007 ppm) + (0.02 cfs)^ = (3.0 cfs +
0.02 cfs) X (0.1 ppm)
14-05 ppm
For QGW = 1.92 cfs
(3.0 cfs) X (0.007 ppm) + (1.92 cfs)CACL
1.92cfs)X(0.1 pprn)
PPm
= (3.0 cfs+
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Scenario 2
Utah Agricultural Standard:
= °-1 PPm
Background Surface-Water:
C = °-007
BKG
(SW-2 maximum)
Ground-Water Flow:
K=14ft/d
i = 0.001 2 ft/ft
A = 38,500 ft2
= 0.0075 cfs
(MW-112 slug tests)
(1/97 ground-water flow between
MW-112andWell-2)
(A = b XI = 11 ft X 3500 ft)
Surface-Water Flow:
QSW = 2.5 cfs
(Estimated)
ACL:
(2.5 cfs) X (0.007 ppm) * (0.0075 cfs)CACL = (2-5 cfs +
0.0075 cfs)X (0.1 ppm)
31-1 PPm
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