MIDVALE, UTAH 

Prepared by 

U.S. Environmental Protection Agency, Region 8 

1595 Wynkoop 

Denver, CO 80202-1129 

September 2014 
2.4 Remedial Investigation/Feasibility Studies .................................................................... 4 2.5 Record of Decision ......................................................................................................... 5 

2.5.1 Operable Unit 1 .................................................................................................. 5 

2.5.2 Operable Unit 2 .................................................................................................. 6 

2.6 Remedial Activities ........................................................................................................ 7 

2.6.1 Operable Unit 1 .................................................................................................. 7 

2.6.2 Operable Unit 2 .................................................................................................. 8 

2.6.3 Operable Units 1 and 2 ....................................................................................... 8 

2.7 Institutional Controls ...................................................................................................... 9 

3.0 GROUNDWATER MONITORING RESULTS ............................................................... 9 

4.0 REUSE /REDEVELOPMENT .......................................................................................... 10 

5.0 OPERATION AND MAINTAINENCE ........................................................................... 10 

6.0 DEMONSTRATION OF CLEANUP ACTIVITY QUALITY 

ASSURANCE/QUALITY CONTROL ............................................................................. 11 

7.0 FIVE-YEAR REVIEWS ......................................•............................................................. 11 

8.0 SITE COMPLETION CRITERIA ................................................................................... 11 

BIBLIOGRAPHY..................................................................................................................... Bl 
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(RODs) and Explanations of Significant Differences (ESDs) issued for Site. 

2.0 SUMMARY OF SITE CONDITIONS 

2.1 Site Background 

The 446-acre Midvale Slag Superfund Site is located 12 miles south of Salt Lake City in the city 

of Midvale, with a small portion extending into the adjacent city of Murray. The Site is divided 

into two operable units. Midvale Slag Operable Unit 1 (OU1) encompasses approximately 266 

acres in the northern portion of the Site, and primarily consisted of buffer land where minimal 

smelter operations occurred. Operable Unit 2 (OU2) encompasses approximately 180 acres in the southern portion of the Site and was the location of the smelter buildings and operations. The 

Site is bordered to the south by 7800 South Street, to the west by the Jordan River, to the north 

by 6400 South Street (Winchester A venue), to the northeast and east by 700 West Street and to 

the southeast by Holden Street. Ore processing and smelting operations were conducted at the 

Site and the adjacent Sharon Steel Superfund Site, located immediately south of OU2. The 

Sharon Steel Superfund Site and the Midvale Slag Superfund Site have been historically linked, 

particularly from an environmental perspective. During the operational time of the facility, five 

different lead and copper smelters occupied the Site. The milled ores were smelted at the Site to 

produce lead, arsenic, copper, and other metals. Smelting operations at the Site ceased in 1958. 

Contamination at the Site is associated with smelter and mill waste deposits on OU2 as well as 

small amounts of surface and subsurface slag and contaminated soils on OU1. Contaminants of 

concern (COCs) at the Site include arsenic, barium, cadmium, chromium, copper, lead, mercury, 

selenium, silver and zinc. 

The EPA listed the Midvale Slag Superfund Site on the National Priorities List (NPL) in 1991 

based on studies conducted between 1982 and 1985 that found groundwater, soil and sediments 

contaminated with heavy metals. Potential human health threats included drinking contaminated 

groundwater or ingesting, inhaling, or handling contaminated soils, wastes or sediments. 

The cleanup for this Site includes the following areas: 

1) The former smelter property including buffer land (OU1 and OU2), currently known as 

Bingham Junction, which is owned by individual property owners 

2) Portions of the Jordan River riparian corridor which are adjacent to the former smelter 

property included in both QUI and OU2 

3) Portions of residential properties in the northern portion of the Site including the 

Winchester Estates, all part of OU1 

4) Groundwater beneath the Site for both OU1 and OU2. 

Midvale Slag Site Final Close-Out Report Page 3 
found groundwater, soil and sediments contaminated with heavy metals and arsenic. 

2.3 Removal Actions 

The EPA and the UDEQ conducted investigative work and a series of removal actions. The 

removal actions conducted at the Site include: 

• March 1990, Removal Action for installation of a fence around both operable units. 

• December 1990, Emergency Removal Action to dispose of lab chemicals and explosives 

remaining onsite from abandoned laboratories. 

• April 1995, Time Critical Removal Action to install a fence between OU1 and OU2 

• June 1996, Time Critical Removal Action to properly abandon onsite water supply wells 

remaining from the smelter operations. 

• September 1996, Time Critical Removal Action to address contamination at the 

Butterfield Lumber Company property by excavating contaminated soils and 

backfilling with clean soils. 

• October 1996, Time Critical Removal Action at the Pioneer Cemetery to excavate 

contaminated soils, backfill with clean soils and install fencing around this historic area. 

• October 2001, Time Critical Removal Action to remove approximately 90 deteriorated 

drums and associated debris located in OU1. 

2.4 Remedial Investigation/Feasibility Studies 

OU1: The suspected waste areas within OU1 were a small landfill and an abandoned waste water 

treatment plant with its associated lagoons. Analysis of sample data determined that neither area 

contributed to the contaminants of concern detected in OU1 soils. Soil contamination was caused 

by smelter waste from OU2 transported by wind and surface water as well as deliberate use of 

waste as fill. The Baseline Risk Assessment identified arsenic, cadmium and lead as the 

contaminants of concern for soil at OUl. The initial OU1 Feasibility Studies (FS) were 

completed in 1995 for the North West and South East Winchester Estates, a trailer park located 

on the northern end of the Site, and in 1998 for the remaining portions of OUl. These reports 

were conducted to consider remedial alternatives for the contaminants of concern in soils. 

OU2: The Site investigations for OU2 focused on mixed smelter waste, slag and groundwater. 

These were evaluated during Site investigations conducted for the Engineering Evaluation/Cost 

Analysis (EE/CA) prepared in 1993, the Supplemental Remedial Investigation in 1997 and 1998, 

and additional characterizations performed in 2001 and 2002. Surface and subsurface soil 

samples were analyzed in five mixed smelter waste areas, calcine waste, silver refinery waste 

and contaminated soils. 

Midvale Slag Site Final Close-Out Report Page 4 
smelter waste. Many remedial options were considered, including no action, institutional 

controls, treatment and disposal. Alternatives from each study were combined to form the 

selected remedy. The smelter waste and soil maximum contaminant concentration was 20,400 

mg/kg for arsenic and 26,300 mg/kg for lead. The sediment maximum contaminant concentration 

was 96 mg/kg for arsenic and 721 mg/kg for lead. 

2.5 Record ofDecision 

2. 5.1 Operable Unit 1 

On Apri128, 1995, the EPA issued a Record of Decision for OU1 selecting the following remedy: 

• Excavation of a minimum of 18 inches of soil in 14 residential yards in the Winchester 

Estates development, placement of clean fill and off-site disposal of soils. 

• Placement of a 2-foot thick monolayer soil cover over an undeveloped portion of 

the Winchester Estates. 

• Institutional controls for the area receiving the soil cover. 

• Institutional controls (ICs) for four other parcels prohibiting future residential land 

use without additional remediation. 

• Groundwater monitoring at the hydraulically downgradient Site boundary for a 

minimum of 5 years. 

In May 1998 and also in February 2006, the EPA and UDEQ issued ESDs which changed the 

remedy called for in the 1995 OU1 ROD. The 1998 ESD required the excavation of 

contaminated soils on one parcel of land, rather than capping, and thus eliminated the need for 

ICs on that parcel. The 2006 ESD changed land use restrictions to accommodate multiple land 

uses, created a consistent approach for both operable units, included riparian management (both 

sides of the river) and contained a comprehensive groundwater monitoring plan in coordination 

with the OU2 remedy. The 2006 ESD identified the lack of remedial action objectives for 

groundwater in the OU1 ROD and adopted the remedial objectives selected for groundwater in 

the OU2 ROD. A final ESD was issued in October, 2013, clarifying the groundwater Remedial 

Action Objectives (RAOs) for OUl and OU2. 

The RAOs for OU1, as amended, are as follows: 

• Soil RAO 

Prevent unacceptable exposure risks to current and future human populations 

presented by contact, ingestion, or inhalation of smelter materials, associated 

contaminated materials, or COCs derived from the smelter wastes. 

Midvale Slag Site Final Close-Out Report Page 5 
o Provide that future discharge of contaminated groundwater from the Site to the 

Jordan River is protective ofthe aquatic environment and designated use. 

2. 5. 2 Operable Unit 2 

The EPA signed the OU2 ROD on October 29, 2002. The OU2 ROD defined four categories of 

smelter wastes found throughout OU2. Principal threat wastes such as crude arsenic trioxide were 

designated as Category I waste. Category II wastes included non-slag soils and smelter waste failing 

Toxicity Characteristic Leaching Procedure (TCLP) and containing COCs above commercial land 

use-based remediation goals. Category III wastes included non-slag soils and smelter wastes passing 

TCLP and containing COCs below residential land use-based remediation goals. EPA classified 

slag as Category IV waste. 

The major components of the selected remedy include: 

• Groundwater: The Deep Principal Aquifer which is a primary source of drinking water in 

the Salt Lake Valley, is not impacted by the Site, although the shallower Upper Sand and 

Gravel Aquifer is impacted by the Site. The limited action remedy for groundwater does 

not actively attempt to restore the Upper Sand and Gravel Aquifer (US&G), but provides 

compliance points for monitoring and assessing as well as institutional controls. The 

limited action approach relies on groundwater and surface water monitoring to assess 

whether groundwater and surface water criteria are being met for selected COCs. These 

selected COCs were established as a result of using alternate concentration limit (ACL) 

calculations and site-specific analyses to be protective of surface water quality criteria for 

the Jordan River. An IC to restrict well installation was also selected as a part of the 

remedy. 

The ACLs for the four groundwater COCs were set at the following: 

o Arsenic 7,000 llg/L 

o Cadmium 1,560 llg/L 

o Selenium 900 1-Lg/L 

o Antimony 3 80 1-lg/L. 

• Mixed Smelter Waste: The selected remedy for mixed smelter waste required the 

excavation and off-site disposal of Category I Material, if found, and the installation of 

appropriate covers over the remainder of the Category II and III Materials. 

• Slag: The selected remedy for the slag (Category IV Material) required re-grading of the 

slag piles and the installation of appropriate covers. 

• Land use controls (ICs) were also selected for OU2 to restrict future excavations and guide 

future use of the property. 

Midvale Slag Site Final Close-Out Report Page 6 
• Groundwater RAOs 

o Prevent unacceptable exposure risk to current and future human populations presented 

by direct contact, inhalation, or ingestion of contaminated groundwater. 

o Provide that future migration of COCs into previously uncontaminated portions of the 

US&G Aquifer and into the Deep Principal Aquifer is protective of these aquifers as 

sources of drinking water. 

o Provide that future discharge of contaminated groundwater from the Site to the Jordan 

River is protective of the aquatic environment and designated use. 

• Mixed Smelter Waste RAOs 

o Prevent unacceptable exposure risks to current and future human populations presented 

by contact, ingestion, or inhalation of smelter materials, associated contaminated 

materials, or COCs derived from the smelter areas. 

o Prevent unacceptable exposure risks to current and future ecological receptors presented 

by contact, ingestion, inhalation, or uptake from smelter materials, associated 

contaminated materials, or COCs derived from the smelter areas. 

o Provide that the future migration of contaminants from the smelter materials is within 

limits considered protective of groundwater. 

o Prevent smelter materials from entering the Jordan River via surface water flow. 

• Slag RAOs 

o Prevent unacceptable exposure risks to current and future human populations presented 

by contact, ingestion, or inhalation of slag or associated contaminated materials. 

o Prevent unacceptable exposure risks to current and future ecological receptors presented 

by uptake from slag, associated contaminated materials within slag, or COCs derived 

from the slag areas. 

o Provide that the future migration of contaminants from the slag or contaminated 

materials within slag is within limits considered protective of groundwater. 

o Prevent slag or contaminated materials within slag from entering the Jordan River via 

surface water flow. 

2. 6 Remedial Activities 

2. 6.1 Operable Unit I 

UDEQ was the lead agency for the OU1 remediation as defined in a cooperative agreement between the EPA and UDEQ. Remediation work was conducted in two phases, with the 

Winchester Estates portion of the remediation beginning in September 1995 and ending in April 

1996. The second phase of the OU1 remediation began in July 1998. The final inspection of the 

Midvale Slag Site Final Close-Out Report Page 7 
owner, Littleson, Inc., agreed to perform the remedial design/remedial action (RD/RA) for the 

smelter wastes, slags and impacted soils components of the 2002 ROD remedy. In the consent 

decree, Midvale City agreed to enact and enforce ICs in the form of an ordinance. This consent 

decree was entered on November 16, 2004. 

UDEQ was the lead for the groundwater portion of the 2002 ROD remedy as well as the 2006 

ESD for OU1. This work was performed under a cooperative agreement with the EPA. The EPA 

was the primary lead for the riparian portion of the 2002 ROD remedy. 

Smelter Wastes, Slags, and Impacted Soils 

Littleson, Inc., completed all remedial activities as planned, and no additional areas of 

contamination were identified. The EPA, UDEQ and Midvale City conducted a final inspection of 

the work upon completion of the physical construction on June 26, 2006. A one-year warranty 

period began on July 6, 2006, to ensure that the remedy continued to operate as designed. On May 

15,2007, the EPA, UDEQ and Midvale City representatives conducted a second final inspection 

to verify that the remedy remained effective. This remedy was declared operational and functional 

on August 13,2007 when the EPA approved the Remedial Action Report. On the same day, the 

EPA certified the completion of the construction work required under the consent decree. 

2. 6. 3 Operable Units 1 and 2 

Riparian Zone 

The EPA and UDEQ conducted the RD/RA work along 6,800 feet of the Jordan River riparian 

corridor adjacent to the western boundary of the Site. The objective for this work included the 

reduction and elimination of river bank erosion that could release smelter waste from the Site 

into the river. This work was conducted in four phases, with the final phase being completed in 

August 2011. Salt Lake County conducted the Phase 3 portion of this work under the EPA and 

UDEQ oversight. Phase 3 involved completing the riparian work from Winchester Estates south 

along the eastern bank ofthe Jordan River and was funded through a grant from the EPA using 

special account money. 

The EPA, UDEQ and Salt Lake County completed all remedial activities as planned. The EPA 

and UDEQ conducted a pre-final inspection on August 10, 2011, which resulted in a schedule for 

the contractor to correct minor items. The remaining "punch" list item was replacement of some 

damaged vegetation. The EPA and the State determined that all Riparian Zone work was 

constructed and/or completed according to the ROD and design specifications. 

Groundwater 

UDEQ completed the installation of the groundwater monitoring system in December 2008. 

Construction of the system was completed under a cooperative agreement established between 

the EPA and UDEQ. Under this cooperative agreement, UDEQ implemented the groundwater 

monitoring system design developed by the EPA and conducts quarterly monitoring. In 

Midvale Slag Site Final Close-Out Report Page 8 
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Section 1 7-7-9.11, Institutional Controls) to prevent exposure to contaminated materials and to 

restrict future excavations. In addition, Midvale local land use controls restrict surface water 

management and irrigation practices to limit infiltration in the plume area. The ICs also provide 

for periodic inspection and long-term maintenance of covers. 

On June 26, 2007 Midvale City adopted ordinance No. 6/26/2007 0-8 to restrict groundwater 

use, to regulate surface water management and irrigation practices, and to require vapor 

mitigation systems for buildings constructed over the PCE plume. This ordinance amends and 

replaces the ordinance adopted by Midvale City in 2004. Groundwater use at the Site is also 

restricted through the Sharon Steel Restricted Area which the Utah Division of Water Rights 

(UDWR) administers through the Salt Lake Valley Groundwater Management Plan. 

Restrictive covenants are also in place on the former Littleson and Union Pacific Railroad 

properties. 

Littleson implemented the smelter waste and slag RD/RA with an eye towards redevelopment. 

The Bingham Junction plan envisioned commercial, industrial, retail and both single and multifamily homes at the Site. Today a large-scale, mixed-use development is being constructed on 

both OUl and OU2. 

3.0 GROUNDWATER MONITORING RESULTS 

UDEQ conducts semi-annual groundwater and surface water monitoring at the Site using a plan 

developed during the remedial design. The monitoring system at the Site currently consists of colocated wells at 15 locations (a total of 3 0 wells) and two surface water sampling locations. Each 

well pair consists of one shallow monitoring well, screened in the upper interval of the US&G 

Aquifer, and one intermediate monitoring well, screened at a lower interval within the US&G 

Aquifer. The monitoring system is divided into four groups and consists of up-gradient, downgradient, plume core and ACL monitoring wells. The process for developing ACLs is discussed 

in the OU2 ROD with supporting documentation provided in the Administrative Record. 

Although the selected remedy did not attempt to actively restore the US&G aquifer, it provided 

for the monitoring of groundwater and surface water to assess whether applicable groundwater 

and surface water quality criteria are being met for the selected COCs. It also provided for the 

creation of ICs to prevent exposure to the contaminated US&G aquifer. 

Point of assessment locations for monitoring the US&G aquifer were selected based on the 

location and movement of arsenic contamination on the Site. Arsenic was selected as the indicator 

chemical since it is the most mobile and widespread of the COCs in this aquifer. Monitoring wells 

for points of assessment were installed in the shallow and deep portions of the US&G aquifer in 

accordance with plans and specifications developed during the remedial design. 

Midvale Slag Site Final Close-Out Report Page 9 
The UDEQ's Semi-Annual Groundwater and Surface Water Monitoring Report- Midvale Slag 

Superfund Site dated May 24, 2013 states that "COC concentrations in the ACL monitoring 

wells have not exceeded their respective ACL values and that COC concentrations in surface 

water have not exceeded established surface water quality criteria values for the Jordan River in 

monitoring results from 2008 to present." 

4.0 REUSE /REDEVELOPMENT 

Because the community requested future land use be considered in the remedy selection, slag 

piles were graded to better support redevelopment and appropriate soil covers were designed as 

an interim measure to facilitate future redevelopment. The Site is located right off the I -15 and I215 freeways, within 20 minutes of most Salt Lake County locations. On August 29,2006, 

Midvale Mayor Joanne Seghini said, "The land constitutes 20 percent of Midvale and is one of 

the last pieces of undeveloped property in the city and was a discouraging blight." Redevelopment began once the institutional controls were established and the Ready for Re-use 

Determination was issued on May 23, 2008. 

Today, approximately 65 percent of the Site has been fully developed for mixed-use that 

incorporates major retail and office space, along with needed housing for Midvale City. The Utah 

Transit Authority mass transit train system opened a station at the Site which serves the new 

"green sustainable community." The successful revitalization of the Midvale community is 

sustainable, provides mixed use, and elevates the quality of life with revitalization for years to 

come. Improvement of the riparian corridor and bike trail along the Jordan River has also helped 

this area thrive. These successful efforts have resulted in the influx of new residents now 

inhabiting the Site fulfilling the initiative for revitalization envisioned years ago by Midvale City, 

UDEQ and the EPA. 

5.0 OPERATION AND MAINT AINENCE 

Maintaining appropriate soil cover and drainage is a required operation and maintenance I C. Midvale City is responsible for enforcing the cap and soil ICs through conducting the following 

activities: inspection/observation during redevelopment construction; review of development 

construction plans and specifications for conformance with cover requirements; storm water 

management and irrigation restrictions; and temporary stockpile and covering of soil and slag. 

UDEQ conducts semi-annual groundwater and surface water monitoring at this Site. In 

monitoring results from 2008 to present, COC concentrations in the ACL monitoring wells have not exceeded their respective ACL values and COC concentrations in surface water have not 

exceeded established surface water quality criteria values for the Jordan River. 

Midvale Slag Site Final Close-Out Report Page 10 
The Quality Assurance Project Plan for the Site incorporated the EPA QAIQC procedures and 

protocols. The EPA analytical methods were used for all confirmation and monitoring samples 

during removal and remediation activities. The EPA and UDEQ determined that QA/QC 

protocols and procedures were adhered to in order to assure satisfactory execution of the 

response actions. 

7.0 FIVE-YEAR REVIEWS 

Three statutory five-year reviews have been conducted at the Site, the first in October 2003, 

the second in December 2008 and the latest in April2014. No issues were identified in the 

2014 five year review. The Site-wide remedy protects human health and the environment 

because exposure pathways that could result in unacceptable risks are being controlled through 

the completed remedial activities and effective ICs. The next five-year review is scheduled for 

completion in April2018. 

8.0 SITE COMPLETION CRITERIA 

This Site meets all the Site completion requirements as specified in the OSWER Directive 

9320.2-22, Close-Out Procedures for National Priorities List Sites. All remedial activities at the 

Midvale Slag Site are consistent with agency policy and guidance. The only remaining CERCLA 

activities to be performed at the Site are O&M and five-year reviews. Therefore, the EPA has 

determined that no further response action is necessary at the Midvale Slag Site to protect human 

health and the environment. 

Approved by: 

Martin Hestmark 

Assistant Regional Administrator 

Office of Ecosystems Protection 

and Remediation 

Midvale Slag Site Final Close-Out Report 

Date 

Page II 
CDM, Federal Programs Corporation 2002. Final Site Characterization Report, Final Phase II 

Site Characterization Report, Midvale Slag Superfund Site, Operable Units 1 and 2. May. 

SEMS# 494559 

USEPA, 2002. Midvale Slag Superfund Site OU2 Midvale, Utah; Record of Decision. October 29. 

SEMS # 2003421 

USEPA, 2003. First Five-Year Review Reportfor Midvale Slag. October 20. SEMS# 1064962 

CDM Federal Programs Corporation, 2004. Final Groundwater and Surface Water Monitoring 

Plan Midvale Slag Operable Units 1 and 2, Midvale Utah. September 30. SEMS# 1128659 

CDM Federal Programs Corporation, 2005. Technical Memorandum: Evaluation of the Mineral 

Resources Reclamation Company (MRCC) Property Area for Operable Unit 2; Midvale Utah. 

June 1. SEMS# 1072871 

CDM Federal Programs Corporation, 2005. Technical Memorandum for Preliminary Remediation 

Goals and Decision-Making Process at Midvale Slag OU1. June 1. SEMS# 1072871 

CDM Federal Programs Corporation, 2005. Final Summary of Groundwater Sampling Activities 

before Remedial Action at the Midvale Slag Superfund Site, Operable Units 1 and 2. July. 

SEMS# 1025159 

USEPA, 2007. Technical Clarification of OU2 Record of Decision. August 10. SEMS# 1074952 

USEP A, 2006. Explanation of Significant Differences, Midvale Slag Superfund Site, Midvale, 

Utah, Operable Unit 1. February 14. SEMS# 1052312 

USEPA, 2008. Ready for Reuse Determination. May 23. SEMS# 1072872 USEPA, 2008. Second Five-Year Review Report for Midvale Slag Supe1jund Site. December. 

SEMS# 1092845 

URS Corporation, 2009. Final Monitoring Well Installation Report for the Midvale Slag 

Superfund Site Groundwater Monitoring System, Midvale Utah. May. SEMS# 1117644 

URS Corporation, 2009. Final Quarterly Groundwater and Surface Water Monitoring Report, 

Third Quarter. November. SEMS# 1128655 

URS Corporation, 2010. Final Semi-Annual Groundwater and Surface Water Monitoring Report, 

Semi-Annual Sampling: Spring 2010, Midvale Slag Superfund Site Midvale, Utah. September. 

SEMS# 1167643 

Midvale Slag Site Final Close-Out Report- Bibliography Page Bl 
USEPA, 2004. Institutional Control Process Plan, Operable Unit No. I, Midvale Slag Site. 

Attachment to the RD/RA Consent Decree, Civil No. 2:04 CV-843. 

Midvale City, 2007. Ordinance No. 06126/07 0-8. An ordinance creating Section 8.10 in Chapter 

8 of the Midvale Municipal Code titled "Institutional Controls Ordinance for Bingham 

Junction, Jordan Bluffs and Designated Rights-Of-Way." 

USEP A 2011. Preliminary Closeout Report. September. 

Midvale Slag Site Final Close-Out Report- Bibliography Page B2