1118360-RBSDMS 

Remedial Action Report 

Record of Preparation, Review and Approval 

Midvale Slag Superfund Site 

Ground-water 

This report has been prepared in accordance with EPA OSWER Directive 9320.2-09A 

and will be used as a basis for development ofthe Final Closeout Report. 

Remedial Action Report Prepared By: 

Tony Howes 

Environmental Scientist/Project Manager 

Utah Department of Environmental Quality 

Remedial Action Report Approved By: 

Bill Murray, Director 

Superfiind Remedial Program 

Environmental Protection Agency, Region VIII 

lliy 1^7 
REMEDIAL ACTION REPORT 

MIDVALE SLAG SUPERFUND SITE, MIDVALE, UTAH 

EPA CERCLIS ID NUMBER UTD081834277 

GROUND-WATER 

I. INTRODUCTION 

The Midvale Slag Superfimd Site is located in a commercial and residential area of 

Midvale City, Utah. The Sharon Steel Superfund Site (UTD980951388) and Jordan 

River lie immediately adjacent to the Site. Redevelopment activities are currently 

underway at the Site and include the construction of high density residential and 

commercial areas. The property owner has completed several residential areas that are 

now occupied. Midvale City estimates that approximately 6,900 residents will live at the 

Site after redevelopment is complete. 

A lead and copper smelter and milling facility operated at the Site from 1871-1971. The 

facility also produced other metals, including gold and silver. Wastes generated from the 

smelting and milling process were disposed of on-site. These wastes included arsenic 

trioxide, calcine, slag and other smelter-related wastes. 

Ground-water beneath the Midvale Slag Site is comprised of three distinct hydrogeologic 

units: the unconfined upper sand and gravel aquifer (US&G) which is also referred to as 

the shallow unconfined aquifer, the confined deep principal aquifer and a local perched 

unit. Wastes generated and disposed of on-site contaminated the US&G aquifer 

primarily with arsenic. A tetrachloroethene (PCE) plume also exists at the Site and 

originates from a source east and upgradient ofthe Site. 

The Site has been the subject of envirormiental concem since 1982 when the first known 

investigation was completed. The results of this and other investigations found elevated 

levels of heavy metal contaminants in soils, surface-water, sediments and ground-water at 

the Site. In June 1986 the EPA proposed that the Site be placed on the National Priorities 

List (NPL); it became final in Febmary 1991. 

The Environmental Protection Agency (EPA) and Utah Department of Environmental 

Quality (UDEQ) addressed the Site as two operable units (QUI and 0U2). Operable 

Unit 1 comprises the northem portion ofthe Site and includes the Winchester Estates 

Mobile Home Park. Remedial activities at OUI were completed in March 1999 and 

included the excavation and disposal of contaminated soils. Operable Unit 2 comprises 

the southem 180 acres ofthe Site. The selected remedy for 0U2 addressed contaminated 

ground-water, mixed smelter wastes, slag, and soils. The property owner completed 

remedial action activities that addressed mixed smelter wastes, slag and soils at 0U2 in 

May 2007. The EPA and UDEQ allowed the property owner to abandon monitoring 

wells previously installed at the Site for ground-water investigation purposes in order to 

facilitate work associated with the remedial action activities that addressed mixed smelter 

wastes, slag, and soils. Ground-water and the installation of new wells were not 

1 
addressed as part of the remedial activities completed by the property owner. Instead the 

EPA and UDEQ deferred action on ground-water until a later date. 

The 0U2 ROD, which is the subject ofthis report, was signed October 29, 2002. 

II. OPERABLE UNIT BACKGROUND 

The remedy selected for ground-water did not actively attempt to restore the Upper Sand 

and Gravel (US&G) aquifer. Instead, the remedy established monitor ing points for 

assessing ground-water conditions and required the implementation of institutional 

controls. The major components ofthe ground-water remedy selected in the 0U2 ROD 

consisted ofthe following: 

• Provide ground-water and surface water monitoring to assess whether applicable 

grotmd-water and surface water quality criteria are being met for the selected 

contaminants of concem (COCs) (antimony, arsenic, cadmium, and seleniimi). 

Points of assessment will be used to give regulatory agencies an early indication if 

contamination is spreading laterally or vertically v^dthin the boundaries ofthe Site. 

Analyses of samples collected from monitoring locations established within the 

inorganic contaminant plume along the Jordan River will be assessed against 

altemate concentration limits (ACLs) established based on the results of sitespecific analyses and calculations. 

• Establish institutional controls (ICs), including expanding the Sharon Steel 

Restricted Area to include the US&G aquifer; restricting surface water 

management and irrigation practices to limit infiltration over the US&G inorganic 

contaminant plume and its source areas; and requiring buildings constmcted over 

the US&G aquifer PCE plume to install indoor air vapor systems. 

In Febmary 2006 the EPA issued an ESD to clarify certain modifications ofthe OUI 

remedy decision regarding land use restrictions, the riparian zone, and ground-water. 

The ESD identified the lack of remedial action objectives for ground-water in the OUI 

ROD and adopted the remedial objectives selected for groimd-water in the 0U2 ROD. 

On June 26, 2007 the city of Midvale adopted institutional controls as ordinance No. 

6/26/2007 0-8. This ordinance restricts ground-water use, regulates surface water 

management and irrigation practices, and requires vapor mitigation systems for buildings 

constmcted over the PCE plume. This ordinance amends and replaces the previous 

institutional control process plan adopted as ordinance by Midvale City in May 2004. 

Ground-water use at Midvale Slag is also restricted through the Sharon Steel Restricted 

Area which the Utah Division of Water Rights (UDWR) administers through the Salt 

Lake Valley Ground-water Management Plan. 

III. CONSTRUCTION ACTIVITIES 

The URS Corp, at the direction of UDEQ constmcted a ground-water monitoring system 

of 29 two inch monitoring wells at the site in December 2008. An existing monitoring 

well installed for investigation purposes and not abandoned to facilitate work completed 

by the property owner was found to be in good working order. The UDEQ incorporated 

this well into the monitoring system constmcted in December 2008. The URS drilled and 

2 
installed monitoring wells in accordance with the Utah Administrative Code R655-4 for 

Water Well Drillers. 

The monitoring system consists of collocated wells at 15 locations, for a total of 30 wells 

(Attachment A). Each well pair consists of one shallow-depth monitoring well screened 

in the uppermost interval of the US&G aquifer and one intermediate-depth monitoring 

well screened in a lower interval vsdthin the US&G aquifer. The monitoring system is 

divided into fotir groups based on monitoring objectives and consists of ACL monitoring 

wells, plume core monitoring wells, and upgradient and downgradient monitoring wells. 

The specific objective for each ofthese groups is as follows: 

• The ACL monitoring wells assess the concentration and distribution of COCs 

prior to discharge to the Jordan River. 

• Plume core monitoring wells assess the concentration and distribution of 

inorganic COCs in areas previously shovm to exhibit the highest concentrations of 

these contaminants. 

• Upgradient wells monitor upgradient conditions for the inorganic COCs and also 

serve to delineate the extent of PCE in the US&G aquifer. 

• Downgradient wells assess down and cross gradient conditions between the 

contaminated ground-water and a mimicipal well operated by Murray City. 

Wastes derived during the constmction of the monitoring system consisted of drill 

cuttings and well development water. Efforts were made to separate clean drill cuttings 

from potentially contaminated cuttings, to the extent possible. Potentially contaminated 

drill cuttings were then properly disposed of in the on-site repository. Development 

water was properly disposed of at the City of Midvale's storm drain system, a temporary 

on-site trench, and at the South Valley Water Reclamation facility. 

IV. CHRONOLOGY OF EVENTS 

Date 

October 29, 2002 

September 30, 2004 

September 2004 

Febniary 2006 

May 28, 2008 

September 25, 2008 

November 2008 

December 2008 

January 22, 2009 

January 26 to February 6, 2009 

May 15,2009 

April 24 to May 6,2009 

July 20 to 31,2009 

Ongoing 

Event 

ROD for 0U2 signed 

Ground-water Basis of Design Report is approved 

Ground and Surface Water Monitoring Plan is approved 

ESD regarding ground-water is issued for OU 1 

Cooperative Agreement between EPA and UDEQ approved 

UDEQ directs URS Corp. to install a ground-water monitoring 

system and perform quarterly monitoring for one year 

Ground-water Installation Quality Assurance Plan is finalized 

Construction ofthe ground-water monitoring system 

Sampling and Analysis (SAP) & Quality. Assurance Plans 

First quarter of ground and surface water monitoring is completed 

Monitor Weil Installation Report is finalized and approved 

Second quarter of ground and surface water monitoring 

Third quarter of ground and surface water monitoring 

Quarterly ground and Surface water monitoring 
V. PERFORMANCE STANDARDS AND CONSTRUCTION QUALITY 

CONTROL 

Monitoring wells were constmcted according to following specifications: 

• At locations where the perched aquifer was encountered. The URS sealed the 

aquifer from the underlying US&G aquifer by drilling and installing a 10-inch 

diameter, schedule 80 PVC casing to a depth that encountered the confining layer, 

roughly 40 feet below the ground surface and filling it with bentonite grout. The 

bentonite grout was allowed to solidify for several days after installing the surface 

casing. Drilling then resumed with an 8 '/4-inch diameter boring through the 

solidified grout and continued to the specified depth. 

• The installed well casings were 2-inch diameter, schedule 40 PVC. The ends 

were threaded for flush joints and no glue, solvents, or lubricating compoimds 

were used to make the coimections. 

• Well screens consisted of 2-inch diameter, schedule 40 PVC with a 0.010-inch 

slot opening and were 10 feet in length. 

• The primary filter pack consisted of 10-20 silica sand, installed to at least 2 feet 

above the screen. The URS bailed the wells for 30 minutes to settle the filter pack 

and additional 10-20 silica sand was added, as necessary to reach the specified 

height. 

• The secondary filter pack consisted of 20-40 silica sand, installed to at least 1 foot 

above the primary filter. 

• The remaining armulus space, to the surface, was filled with either, bentonite 

grout, if above the water table or course granular bentonite, if below the water 

table. 

VI. FINAL INSPECTION AND CERTIFICATION 

The UDEQ conducted a final inspection ofthe ground-water monitoring system on 

August 3, 2009. The EPA and Midvale City previotisly inspected the monitoring system 

on July 1, 2009. Information provided by the URS as part ofthe UDEQ inspection, such 

as ground and surface water monitoring data, indicates the system is fimctioning as 

intended by the design documents. The UDEQ and EPA have determined that 

constmction of the monitoring system is complete; however, it was noted during the 

UDEQ inspection that attachment of well identification labels needed to be completed. 

There were no health and safety problems encountered during constmction of the 

monitoring well system. Work activities proceeded according to the Bingham Junction 

Residential Area Backbone Infrastructure Health and Safety Plan and a URS safe work 

plan developed specifically for ground and surface water monitoring. The Backbone 

Infrastmcture Health and Safety Plan covers geneiral activities at the Site and is 

considered the Site Health and Safety Plan. 
VII. OPERATION AND MAINTENANCE 

The URS completed first and second rounds of quarterly ground and surface water 

monitoring at the Midvale Slag Site in Febmary 2009 and May 2009, respectively. 

Reports documenting the findings ofthe first and second roimds of monitoring have been 

received by the UDEQ and EPA. Ground and surface water samples collected during 

these events were analyzed in accordance v^th the USEPA Contract Laboratory 

Procedure (CLP), by ALS Datachem, a CLP certified laboratory. Metal concentrations in 

groimd and surface water samples did not exceed performance standards established in 

the 0U2 ROD. Groundwater elevations recorded during the first and second monitoring 

events show ground-water in the US&G aquifer flows towards the northwest and does 

not appear to be spreading within the bomidaries ofthe site. 

The UDEQ will continue to conduct groimd and surface water monitoring at Midvale 

Slag in order to determine if ground and surface water quaility criteria are being met and 

to insure that the plume is not spreading. However, based upon the results ofthe first two 

quarterly monitoring events, the UDEQ and EPA anticipate changing to semi-annual 

ground and surface water monitoring in the spring of 2010. 

VIII. SUMMARY OF PROJECT COSTS 

Estimated costs for tasks specific to the installation of the ground-water monitoring 

system, quarterly monitoring, and operation and maintenance (O&M) are as follows: 

TASK 

1. Project Management 

2. Review of Groundwater Design 

3. Installation of Grouftd-water Monitoring System 

4. Groimd and Surface Water Design Sampling/Monitoring 

5. Database and GIS Support 

6. Annual Operation and Maintenance 

TOTAL 

COST ESTIMATE 

$14,894.23 

$2,546.99 

$304,811.88 

$174,093.90 

$18,378.51 

$235,950.00 

$750,675.51 

IX. OBSERVATIONS AND LESSONS LEARNED 

• The URS utilized a local drilling company to install ground-water monitoring 

wells. The use of a local drilling company reduced mobilization costs and 

provided a financial and employment benefit to the local economy. 

• The abandonment of an existing monitoring well (MW-504s) was not required in 

order to perform work that addressed mixed smelter wastes, slag and soil. This 

monitoring well was incorporated into the overall design and reduced costs 

associated with drilling and developing a well at this location. 

• Constmction derived wastes were disposed of in the on-site repository. Disposal 

of theise wastes in the on-site repository benefited the overall constmction of the 

monitoring system as it eliminated concems related to off site disposal, and 

reduced the tune spent handling and transporting the wastes. 
X. CONTACT INFORMATION 

The UDEQ used the following contractor for the ground-water RA: 

Tammi Messersmith 

URS Corportation 

756 East Winchester Sfreet 

Suite 400 

Salt Lake City, Utah 84107 

801-904-4000 

www.urscop.com 

The UDEQ Project Manger is: 

Tony Howes 

168 North 1950 West 

Salt Lake City, Utah 84114 

801-536-4283 

thowes(a),utah. gov 

The EPA Project Manger is: 

Ema Waterman 

US EPA Region 8 

1595 Wynkoop 8EPR-SR 

Denver, CO 80202-1129 

303-312-6762 

waterman. ema@epa. gov 
ATTACHMENT-A 

MAP OF MONITORING WELL LOCATIONS 
^ Monitorin

g Well Pair 

(S - Shallow and I - Intennediate) 

• Surface Water Sampling Location 

0 200 400 600 9 Feet 

Figure 1. Site and Location Map 

Groundwater and Surface 

Water Monitoring Project Plans 

Midvale Slag Superfund/ 

Proposed Bingham Junction Site 

@ (^ ) 

January 2009 

URS