Metals Leaching from Highway Test Sections 

Constructed with Industrial Byproducts 

by 

Jacob J. Sauer, Craig H. Benson, and Tuncer B. Edil 

Geo Engineering Report No. 05-21 

Department of Civil and Environmental Engineering 

University of Wisconsin-Madison 

Madison, Wisconsin 53706 

USA 

December 27, 2005 
EXECUTIVE SUMMARY 

Metals leaching from industrial byproducts used in highway construction was assessed in 

the field and laboratory. Four byproducts were evaluated: foundry sand and foundry slag from a 

gray-iron foundry and bottom ash and fly ash from a coal-fired power plant. Field leaching 

behavior was evaluated by analyzing samples from lysimeters installed beneath highway test 

sections constructed with the byproducts. Batch water leach tests (WLTs) and column leach 

tests (CLTs) were conducted in the laboratory. All leachates were analyzed for concentrations of 

cadmium (Cd), chromium (Cr), selenium (Se), and silver (Ag). Concentrations from the WLTs 

and CLTs were compared with concentrations measured in the leachate collected in the field and 

with groundwater quality standards stipulated in the Wisconsin Administrative Code. 

Leachate collected in the lysimeters commonly had Cd, Se, and Ag concentrations 

exceeding Wisconsin groundwater quality standards. However, application of dilution factors to 

account for the reduction in concentration expected between the bottom of the pavement 

structure and the groundwater table showed that concentrations exceeding groundwater quality 

standards would not occur if the byproducts layer is at least 5 m above the groundwater table. 

For a separation distance of 1 m, only Cd would modestly (30%) exceed the groundwater quality 

standard directly beneath the centerline of the pavement. 

Peak concentrations from the lysimeters were 4-160 times larger than the WLT 

concentrations. Dilution caused by the large liquid-solid ratio used in the WLTs is largely 

responsible for the disparity between the lysimeter and WLT concentrations. Peak 

concentrations from the CLTs typically were within a factor of 10 of peak concentrations from the 

CLTs, although peak CLT concentrations were as much as 45 times higher and 131 times lower 

than the peak field concentrations. The elution patterns in the field and the CLTs generally were 

similar, although the magnitude of the concentrations differed. An exception is the fly-ashstabilized soil, for which both concentrations and elution patterns from the field and the CLTs 

were similar. 

i 
TABLE OF CONTENTS 

EXECUTIVE SUMMARY ................................................................................................... i

TABLE OF CONTENTS .................................................................................................... ii

1. INTRODUCTION.......................................................................................................... 1

2. PAST LEACHING STUDIES ON BYPRODUCTS ....................................................... 4

2.1 Gray Iron Foundry Sand ......................................................................................... 4

2.2 Gray Iron Foundry Slag .......................................................................................... 6

2.3 Coal Bottom Ash..................................................................................................... 7

2.4 Coal Fly Ash ........................................................................................................... 8

3. MATERIALS............................................................................................................... 11

3.1 Foundry Sand ....................................................................................................... 11

3.2 Foundry Slag ........................................................................................................ 14

3.3 Bottom Ash ........................................................................................................... 14

3.4 Fly-Ash-Stabilized Soil.......................................................................................... 14

4. METHODS ................................................................................................................. 16

4.1 Field Lysimeters ................................................................................................... 16

4.2 Water Leach Tests ............................................................................................... 18

4.3 Column Leach Tests............................................................................................. 18

4.3.1 Columns......................................................................................................... 18

4.3.2 Preparation of Column Test Specimens ........................................................ 19

4.4 Chemical Analysis of Effluent ................................................................................ 20

5. RESULTS AND DISCUSSION................................................................................... 23

5.1 Lysimeters ............................................................................................................ 23

5.1.1 Hydrologic Data ............................................................................................. 23

5.1.2 Metals Concentrations ................................................................................... 25

5.2 Comparison of Elution in Lysimeters and WLTs................................................... 33

5.3 Comparison of Elution in Lysimeters and CLTs ................................................... 36

6. IMPLICATIONS FOR GROUNDWATER QUALITY................................................... 44

7. SUMMARY AND CONCLUSIONS............................................................................. 47

8. ACKNOWLEDGEMENTS .......................................................................................... 49

9. REFERENCES........................................................................................................... 50

APPENDICIES ................................................................................................................ 53

ii 
1. INTRODUCTION 

Soft soils encountered during road construction often are removed and replaced 

with crushed rock to form a sturdy working platform for pavement construction. This 

construction practice can be costly, particularly if the rock needs to he hauled to the 

construction site. As a result, transportation agencies are seeking less costly methods 

to stabilize soft soils and construct working platforms. In some cases, industrial 

byproducts can be used to construct lower cost working platforms that provide equal 

support as those constructed with crushed rock (Tanyu et al. 2004). Use of industrial 

byproducts in this manner also facilitates sustainable construction by re-using materials 

currently being landfilled and reducing the use of virgin natural resources. A concern, 

however, is that contaminants leached from byproducts may contaminate underlying 

groundwater. 

Five test sections were constructed along a 1.4 km stretch of Wisconsin State 

Highway (STH) 60 near Lodi, Wisconsin (USA) to evaluate alternative working platforms 

for highway construction on soft subgrades. For three of the test sections, coarsegrained industrial byproducts (foundry sand, foundry slag, or bottom ash) were being 

used as a working platform placed between the soft subgrade and the granular base 

course material. Fly-ash-stabilized subgrade (a mixture of existing subgrade and 10% 

fly ash by dry weight blended in situ) was used as the working platform in the fourth test 

section. The fifth test section is a control where crushed dolostone, a granular material 

commonly used in Wisconsin, was used for the working platform. 

Profiles of the test sections are shown in Fig. 1. Thicknesses of the byproduct 

layers were selected so that each test section had equal structural capacity as the 

control section. Procedures defined in the Guide for Design of Pavement Structures 

published by the American Association of State Highway and Transportation Officials 

1
Fig. 1. Profiles of the test sections constructed using foundry slag, foundry sand, 

bottom ash, fly ash, and crushed rock (control) at STH 60 near Lodi, WI (AC 

= asphalt concrete). 

2 
(AASHTO 1993) were used to determine the structural capacity. Details of the 

structural design are described in Edil et al. (2002). 

During construction, two pan lysimeters were placed beneath each test 

section to monitor the quality and quantity of water discharged from the base of the 

pavement. Samples were collected from these lysimeters over a 5-year period and 

analyzed for concentrations of cadmium (Cd), chromium (Cr), selenium (Se), and 

silver (Ag). Laboratory tests were also conducted on each of the byproducts using 

batch water leach tests (WLTs) and column leach tests (CLTs), both of which are 

commonly used to assess the suitability of byproducts for re-use. This report 

describes and compares the elution patterns and concentrations observed in field 

and from the WLTs and CLTs. Peak concentrations observed in the field are also 

compared with ground water quality standards stipulated by the State of Wisconsin. 

3
2. PAST LEACHING STUDIES ON BYPRODUCTS 

2.1 Gray Iron Foundry Sand 

Gray-iron foundry sand is a mixture of silica sand, a binding agent (clay or 

chemical), and other finishing additives that is used to form molds and cores for 

casting metals. When clay (typically sodium bentonite, calcium bentonite, or 

kaolinite) is used as the binder, the mixture is referred to as “green sand” (Abichou 

et al. 2000). A portion of the mixture is discarded after each use (Bastian and 

Alleman 1998). Some of this waste sand is used in a variety of construction and 

agricultural applications (Javed and Lovell 1994, Kleven et al. 2000, Abichou et al. 

2000, Naik et al. 2001, Goodhue et al. 2001, Tanyu et al. 2004, Lee and Benson 

2005). However, most waste foundry sand is landfilled. In Wisconsin, more than 

800,000 Mg (1 Mg ≈ 1 US ton) of green sand is landfilled annually (Lee and Benson 

2005). 

Bastian and Alleman (1998) used MicrotoxTM microbial bioassay tests to 

characterize the environmental suitability of foundry sands from iron foundries (11 

sands), a steel foundry (1 sand), and an aluminum foundry (1 sand). Thirteen virgin 

sands (clean sands without any binders or other additives) were also subjected to 

bioassay testing. Leachate for the bioassays was produced from batch tests 

conducted with a 2% NaCl solution with a liquid-to-solid (L-S) ratio of 4:1. Leachate 

from three of the iron foundry sands caused a quantifiable depression in microbial 

activity (i.e. less light emitted from the bacteria) compared to tests on the virgin 

sands. Leachate from the other iron foundry sands caused less inhibition of 

microbial activity than leachate from virgin sands. Leachate from the aluminum and 

steel foundry sands caused greater inhibition of microbial activity than leachates 

from the iron foundry sands or the virgin sands. 

4
Partridge et al. (1998) evaluated groundwater samples and leachates from 

an embankment constructed with foundry sand and an adjacent embankment 

constructed with natural sand. Chemical analyses (Zn, Ni, Cd, Cr, Pb, and Cu) and 

MicrotoxTM and NitrotoxTM bioassays were conducted on the water samples. The 

foundry sand was from a gray iron foundry that uses organic binders. Samples 

were collected from 6 groundwater monitoring wells (4 adjacent to a highway 

embankment constructed using waste foundry sand, 2 near an embankment 

constructed using natural sand) and from 2 lysimeters (one in the foundry sand 

embankment, and one in the natural sand embankment). Samples from the 

lysimeters and monitoring wells in and adjacent to the foundry sand embankment 

showed negative inhibition relative to leachate and groundwater samples from the 

natural sand when tested with the MicrotoxTM bioassays (i.e., the samples enhanced 

microbial activity). Samples from the monitoring wells and lysimeters did not 

enhance microbial activity during NitrotoxTM bioassays. However, the bioassay 

results also showed no differences in microbial growth for samples up-gradient and 

down-gradient of the foundry sand embankment. Only Cd, Ni, and Zn were 

detected in any of the leachates, and the metals concentrations observed were 

generally below USEPA drinking water standards. Samples that exceeded the 

drinking water standards were below requirements for the use of industrial 

byproducts as defined in the Indiana Administrative Code. 

Lee and Benson (2006) conducted water leach tests (WLTs) and column 

leach tests (CLTs) on 12 foundry green sands, a sandy silt, and a clean sand using 

the procedure in ASTM D 3987, which employs a L-S ratio of 20:1 and deionized 

water. Concentrations of Al, Ag, As, Ba, Be, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, 

Sb, Se, Tl, and Zn from the WLTs were compared with maximum permissible 

concentrations specified in the Wisconsin Administrative Code for industrial 

5
byproducts placed below the water table (Wisconsin 2004). None of the materials, 

including the sandy silt and the clean sand, met the criteria for use below the water 

table. Metals concentrations in leachate from the CLTs were higher than 

concentrations from the WLTs, but in all cases the concentrations were below 

USEPA maximum contaminant levels (MCLs). 

2.2 Gray Iron Foundry Slag 

Slag is a byproduct of the metal processing industry that consists of 

impurities that float to the surface of molten material (Proctor et al. 2000). This 

floating material is skimmed off and cooled to form the solid referred to as slag. 

Although the majority of slag is landfilled, some slag is used in civil engineering 

applications (Shen and Forssberg 2002). 

Lind et al. (2001) studied leaching of metals from two roads constructed 

using a ferrochrome steel slag. One road consisted of an older roadway resurfaced 

with a 750-mm-thick layer of slag overlain by asphalt pavement. A control section 

was also included where the older roadway was overlain only with asphalt 

pavement (no slag layer). The other road was a new road constructed only with a 

450-mm-thick layer of slag (no asphalt pavement). 

At both sites, groundwater monitoring wells were installed adjacent to the 

paved and unpaved areas, and adjacent to the asphalt control. The wells were 

installed 1 m and 4 m from the edge of the road. Groundwater samples were 

collected 3 times from each location. For the paved road, Cr concentrations in 

samples collected from the control monitoring wells (area only surfaced with 

asphalt) were comparable to Cr concentrations in samples collected from 

monitoring wells near the slag layers (all < 6 μg/L). For the road with an asphalt 

surface, Cr concentrations in the samples from the monitoring well 4 m from the 

6
slag layer typically were one-half of the concentrations in samples from the 

monitoring well 1 m from the slag layer. 

Ham and Boyle (1990) collected groundwater samples collected from 

monitoring wells at 7 ferrous foundry landfills where a mixture of foundry sand, 

foundry slag, and dust was disposed. Samples were collected from monitoring 

wells up-gradient of the landfill and at the down-gradient limit of waste. None of the 

samples had concentrations of As, Cd, Cr, Pb, Hg, Se, or Ag above USEPA MCLs 

at the time of the study. Ham and Boyle (1990) also conducted USEPA batch 

extraction procedure (EP) tests as well as deionized water leach tests (L-S ratio = 

5:1) on samples of foundry waste collected from the landfills. Leachate from the EP 

test on three of the foundry wastes had concentrations exceeding the MCL for Cd. 

However, Cd was not detected in groundwater at any of the landfills containing 

these foundry wastes. 

2.3 Coal Bottom Ash 

Bottom ash is a coarse residual composed of mineral oxides in crystalline or 

glass form that is collected from dry bottom boilers used at coal-fired power plants 

(Siddiki et al. 2004). Bottom ash is angular, has a porous surface texture (Seals et 

al. 1972), and appears similar to well-graded coarse sand (Tanyu et al. 2004). 

According to the American Coal Ash Association (ACAA), approximately 18 million 

Mg of bottom ash is produced annually in the United States, and 46% of the ash is 

re-used in applications such as structural fill and roadway construction. 

Thayumanavan et al. (2001) conducted an algal bioassay on leachate from 

WLTs conducted on bottom ash and bottom ash in an asphalt pavement mixture 

using distilled water and a L-S ratio of 4:1. Less algal growth was found in tests 

with bottom ash leachate compared to control tests with water. However, when 

7
bottom ash was incorporated as an aggregate in asphalt, algal bioassays on the 

leachate from the bottom ash produced similar results to control tests. 

Goodarzi and Huggins (2001) used a sequential leaching procedure to 

evaluate leaching of As, Cr, and Ni from coal combustion bottom ash. The bottom 

ash was exposed to deionized water, ammonium acetate (NH4C2H3O2), and 

hydrochloric acid (HCl). Concentrations of the NH4C2H3O2 and HCl were not 

specified. No As was leached from the bottom ash exposed to deionized water and 

NH4C2H3O2, but 37.5% of the total As was leached after the bottom ash was 

exposed to HCl. Ni was not leached in water, but 25.7% of total Ni was leached 

when in NH4C2H3O2. All but the final remaining 0.4% of the Ni was leached in HCl. 

Cr in the bottom ash was leached by ammonium acetate (4.1%) and hydrochloric 

acid (95.9%). 

2.4 Coal Fly Ash 

Fly ash is fine-textured particulate that is removed from the exhaust from 

coal combustion. Fly ash particles are spherical and have particle sizes ranging 

between 1 and 150 μm. Most tend to be silt size, between 2 μm and 75 μm 

(Gutierrez et al. 1993, Bin-Shafique et al. 2006). According to the American Coal 

Ash Association (ACAA), 70 million Mg of fly ash was produced in 2003 in the 

United States and 39% was reused in a variety of applications. The remainder was 

disposed in waste containment facilities such as landfills. 

Theis et al. (1977) conducted WLTs on 11 fly ashes at pH 3, 6, 9, and 12 

using deionized water at a L-S ratio of 5:1. The batches were shaken for 24 h. pH 

was controlled with sodium hydroxide and perchloric acid. The leachates were 

tested for As, Cd, Cr, Cu, Pb, Ni, and Zn. Average concentrations observed for all 

11 fly ashes were highest for the tests at pH 3, with the exception of As, which had 

8
the highest concentration at pH 12. For instance, Cr release at pH 3 was 3.9 times 

greater than the Cr release at pH 12, and the Cd release was 6.1 times higher at pH 

3 compared to pH 12. 

Praharaj et al. (2002) performed WLTs on 4 fly ashes from a power plant 

burning sub-bituminous coal. The WLTs were conducted using synthetic rainwater 

(pH 5.6) at L-S ratios of 4, 8, 12, and 16. The leachate was analyzed for Al, Ca, K, 

Mg, Na, P, S, Si, As, Ba, Fe, Mn, Mo, Ti, V, Pb, Zn, Co, Cr, Cu, Ni, and Cd. Cd, Cr, 

Co, and Ni did not leach from the ashes at any L-S ratio. As, Mn, and Mo leached 

at concentrations between 1 and 26 times above drinking water standards 

recommended by the World Health Organization and As, Fe, and Mn leached at 

concentrations between 1 and 6 times higher than USEPA MCLs. Concentrations 

were highest for most of the metals at the lowest L-S ratio, with concentrations 

decreasing with increasing L-S ratio. 

Bin Shafique et al. (2006) performed WLTs and column leach tests (CLTs) 

on soils mixed with sub-bituminous fly ashes. The CLTs were conducted to 

evaluate metals leaching under flow-through conditions more typical of that 

occurring in the field and to provide a comparison to concentrations from the WLTs. 

WLTs were performed on the soils alone, fly ashes alone, and on mixtures 

containing 10% and 20% fly ash (by weight). The WLTs were conducted with 

deionized water at a L-S ratio of 20:1. CLTs were conducted on the soils alone and 

with mixtures containing 10% and 20% fly ash (by weight). Leachate from the 

WLTs and CLTs was analyzed for Cd, Cr, Se, and Ag. 

Analysis of the CLT data showed that release of Cd, Cr, Se, and Ag was 

adsorption controlled, with initial concentrations approximately 50 times the WLT 

concentrations for Cd and Ag and 10 times the WLT concentrations for Cr and Se 

(Bin Shafique et al. 2006). Metals concentrations in leachate from the WLTs and 

9
CLTs varied with fly ash content, which was attributed to the variation in pH with fly 

ash content. 

10
3. MATERIALS 

A summary of the index and physical properties of the byproducts and the 

subgrade soil at the field site can be found in Table 1 along with classifications of 

these materials according to the Unified Soil Classification System (USCS) and the 

AASHTO classification system. Particle size distribution curves for the materials 

are shown in Fig. 2. The foundry slag, foundry sand, and bottom ash are coarsegrained materials in the Unified Soil Classification System (USCS), and the fly ash 

and subgrade soil are fine-grained in the USCS. Additional information on the 

physical and mechanical properties of the foundry sand, foundry slag, and bottom 

ash can be found in Tanyu et al. (2004). 

Water leach tests (WLTs) were conducted on the foundry sand, foundry 

slag, bottom ash, fly ash, and on the soil-fly ash mixtures following the procedure in 

ASTM D 3987. Based on these analyses, all of the byproducts meet the 

requirements in Section NR 538 of the Wisconsin Administrative Code for 

byproducts used in confined geotechnical applications (e.g., materials covered with 

asphalt pavement, as in Fig. 1). Results of the WLTs are discussed in Section 5. 

3.1 Foundry Sand 

Grede Foundries of Reedsburg, WI provided the foundry sand for this study. 

The foundry produces grey iron castings using a mixture of sand, 10% bentonite, 

and ≈ 4% sea coal (powdered coal used as a combustible additive). The foundry 

sand is black in color and classifies as clayey sand (SC) in the USCS and A-2-7 in 

the AASHTO system. Although the sand is coarse-grained (percent fines = 29%, 

see Fig. 2), the bentonite gives the material cohesive properties and plasticity (e.g., 

plasticity index = 9, Table 1). 

11
Table 1. Physical properties and USCS and AASHTO classifications of the foundry sand, 

foundry slag, bottom ash, fly ash, and soil used in the study. 

Material Specific 

Gravity 

D10 

(mm) 

D60 

(mm) Cu 

Percent 

Fines 

(%) 

USCS 

Symbol 

AASHTO 

Symbol 

Foundry Sand 2.55 0.0007 0.25 357 29 SC A-2-7 

Foundry Slag 2.29 0.2 2.5 13 9 SW-SM A-3 

Bottom Ash 2.65 0.2 1.5 8 3 SW A-3 

Fly Ash 2.70 0.001 0.07 70 98 ML A-4 

Subgrade Soil 2.70 0.0006 0.02 33 96 CL A-6 

12
 13

0

20

40

60

80

100

10 1 0.1 0.01 0.001 0.0001

Foundry Sand

Foundry Slag

Bottom Ash

Fly Ash

Subgrade Soil

Percent Finer (%)

Particle Diameter (mm)

Fig. 2. Particle size distribution curves for foundry sand, foundry slag, bottom ash, 

fly ash, and subgrade soil used at STH 60 and for the laboratory tests. 
3.2 Foundry Slag 

The foundry slag is coarse-grained (9% fines) and classifies as well-graded 

sand with silt (SW-SM) in the USCS and A-3 in the AASHTO soil classification 

system. The foundry slag was provided by Grede Foundries in Reedsburg, WI, 

which uses a cupola furnace to prepare molten iron. A cupola furnace is tall 

cylindrical blast furnace that is typically fed with raw metals and a fluxing agent such 

as limestone or dolomite (Sun and Sahajwalla 2004). The raw metals fed into the 

cupola furnace at Grede Foundries come from recycled material, scrap steel, and 

pig iron. Non-metallic additives used in the melt process include coke, limestone, 

and coke fines. 

3.3 Bottom Ash 

The bottom ash used in this study is from a dry bottom furnace at Alliant 

Energy’s Columbia Power Station in Portage, WI that burns sub-bituminous coal 

from the Wyoming Powder River Basin. The bottom ash is coarse-grained material 

that classifies as well-graded sand (SW) in the USCS and A-3 in the AASHTO 

system. 

3.4 Fly-Ash-Stabilized Soil 

The test section with a fly-ash-stabilized subgrade was constructed with fly 

ash from Alliant Energy’s Columbia Power Station that was blended into the existing 

subgrade (10% fly ash by dry weight) to a depth of 300 mm using a reclaimer. 

Immediately after mixing, the mixture was compacted to 15.4 kN/m3

 using a tamping 

foot, steel drum, and rubber tire compactors. The water content was 21% ± 2% 

when the mixture was compacted. Details on the construction can be found in Edil 

et al. (2002). 

14
Columbia Power Station captures the fly ash using electrostatic precipitation 

and stores the ash in a dry silo. The fly ash contains 98% fines and classifies as 

elastic silt (ML) in the USCS, A-4 in the AASHTO system, and Class C in ASTM C 

618, 

The subgrade soil at the STH 60 field site is low plasticity clay (CL) in the 

USCS and A-6 in AASHTO. The natural water content of the subgrade soil is 23%. 

15
4. METHODS 

4.1 Field Lysimeters 

Two pan lysimeters (3.75 m x 4.75 m) were installed beneath each section 

at the STH 60 site to collect leachate draining from the bottom of the profile. A 

schematic of a typical set of lysimeters is shown in Fig. 3. One lysimeter was 

located directly under the centerline of the highway and the other was located at the 

edge, with one-half of the lysimeter under the highway shoulder. The lysimeters 

were constructed with 1.5-mm-thick textured HDPE geomembrane overlain by a 

geocomposite drainage layer. Water collected by the lysimeters drains to 120-L 

HDPE drums located below ground surface adjacent to the highway. Additional 

information on the lysimeters can be found in Bin Shafique et al. (2002). 

Samples were collected from the drums periodically. The sampling 

frequency depended on the rate of drainage from the lysimeters, which varied 

seasonally. Sampling was least frequent in the winter when freezing occurred and 

most frequent in the spring when snowmelt and rainfall are more common. During 

each sampling event, water contained in each drum was removed with a pump, the 

total volume of water in the drum was recorded, and samples were collected for 

chemical analysis. Methods used for filtering, preserving, and storing the samples 

are described in Section 4.4. 

Monitoring wells were also installed adjacent to the sections constructed 

with fly ash and bottom ash. However, because the fine-grained subgrade soils at 

the field site have very low hydraulic conductivity, samples could not be collected 

from the monitoring wells during the monitoring period. A description of the 

monitoring wells is in the appendix. 

16
Working Platform

A) 

Shoulder 

Legend: 

Tank 

Center Line 

Lysimeter 

Collection 

Note: Not to Scale 

B) 

120 L Barrel 

Lysimeter 

Subgrade 

125 mm-Hot Mixed Asphalt 

355 mm-Base 

Byproducts or Crushed Rock 

Fig. 3. Plan view (A) and cross-section (B) of typical lysimeter beneath pavement 

structure. 

17
4.2 Water Leach Tests 

Water leach tests (WLTs) were conducted on the byproducts following the 

methods in ASTM D 3987, where 70 g of dry solid is mixed with 1400 ml of ASTM 

Type II water (L-S ratio = 20:1) in 2 L HDPE bottles that are rotated continuously for 

18 hr at 29 rpm. After rotation, the solution was allowed to settle for 5 min and the 

supernatant was collected, filtered, and the pH was recorded. Samples of the 

supernatant were stored in sealed HDPE bottles with no headspace. 

4.3 Column Leach Tests 

Column leach tests (CLTs) were conducted on each of the industrial 

byproducts to evaluate leaching under flow-through conditions. CLTs on the 

cohesionless materials (foundry slag and bottom ash) were conducted using rigidwall permeameters, whereas flexible-wall permeameters were used for the cohesive 

materials (foundry sand and fly-ash-stabilized soil). 

4.3.1 Columns 

The rigid-wall procedure was adapted from the procedure described in Lee 

and Benson (2006). Specimens were compacted directly into a PVC column having 

the same size as a standard Proctor mold (102 mm in diameter and 114 mm tall). 

Non-woven needle-punched geotextiles were placed on the top and bottom of the 

specimen to ensure uniform flow and to prevent solids from entering the influent and 

effluent lines. Acrylic end plates with o-rings were used to seal the ends of the 

column. Upward flow was imposed using a peristaltic pump set at 30 mL/hr (9 

mm/d) for the first 1.5 pore volumes of flow (PVF) and 7 mL/hr (2 mm/d) for the 

remainder of the test. The flow rate was reduced after 1.5 PVF to permit practical 

sample collection intervals. 

18
The procedure described in Bin Shafique et al. (2002) was used for the 

flexible-wall tests. Test specimens were placed in the permeameter between acrylic 

end caps and sealed with a latex membrane. Non-woven needle-punched 

geotextiles were placed between the ends of the specimen and the end caps to 

promote uniform flow and to prevent solids from entering the influent and effluent 

lines. A hydraulic gradient between 7-12 was used to drive the flow in an upflow 

mode. An effective confining pressure of 15 kPa was applied to simulate the stress 

existing in the field. 

A 0.1 M LiBr solution was used as the influent for all column tests. The 

solution was prepared by dissolving LiBr salt (99+% pure, from Aldrich Chemical 

Company) in de-ionized water followed by exposure to the atmosphere until pH 6 

was reached. The concentration was selected so that the ionic strength was similar 

to pore water in pavement layers (Karczewska et al. 1996). Effluent from the 

columns was collected in sealed Teflon bags that were emptied after approximately 

30~60 mL of flow accumulated (≈ 0.1 PVF). Volume and pH of the effluent were 

recorded each time a bag was emptied and a 45 mL sample was collected for 

chemical analysis. Methods used to handle, preserve, and store the samples for 

chemical analysis are described in Section 4.4. 

4.3.2 Preparation of Column Test Specimens 

Slag and bottom ash used in the rigid-wall CLTs was crushed by hand 

through a No. 4 sieve (4.8 mm openings) to remove large particles before preparing 

test specimens. Large particles that could not be crushed though the sieve were 

discarded (< 5% for slag, 0% for bottom ash). The materials were tamped into the 

PVC molds in 3 lifts using a standard Proctor hammer until the dry unit weight used 

in the field was reached (foundry slag: 12.4 kN/m3 , bottom ash: 17.1 kN/m3 ). 

19
The soil-fly ash mixture was prepared using standard Proctor methods 

(ASTM D 698) at a molding water content approximately 2% dry of optimum water 

content to simulate conditions that existed during construction of the test sections 

(Bin Shafique et al. 2002). A mixture containing 90% air-dried soil and 10% fly ash 

(by weight) was blended by hand until uniform and then sprayed with deionized 

water until the desired water content (17.3%) was reached. The mixture was 

compacted one hour after mixing to simulate the delay between mixing and 

compaction that occurs during construction. After compaction, the specimens were 

extruded from the compaction molds, sealed in plastic, and cured for 7 days in a 

100% humidity environment prior to testing to simulate the condition existing in the 

field (Edil et al. 2002). The specimen was compacted to a dry unit weight 15.4 

kN/m3

, which is the same dry unit weight obtained in the field. 

The foundry sand was prepared at a water content of 23% and a dry unit 

weight of 15 kN/m3

 to simulate the condition existing in the field (Edil et al. 2002). 

Prior to compaction, the material was dried and crushed through a No. 4 sieve (4.8 

mm openings) followed by re-moistening by spraying and blending with tap water 

until the desired water content was obtained. The foundry sand was placed in 3 

lifts, with each lift tamped with a standard Proctor hammer until the target density 

was reached. After compaction, the specimens were extruded and placed into the 

flexible-wall permeameter. 

4.4 Chemical Analysis of Effluent 

Procedures described in Bin Shafique et al. (2002) were followed for sample 

handling, preservation, analysis, and quality control. All samples were filtered 

through a 0.45-μm membrane filter as required in ASTM D 3987, acidified to pH < 2 

using metals-grade nitric acid, and stored in sealed HDPE bottles at 4°C prior to 

20
testing. Blanks were prepared and handled using the same protocol used for the 

other samples. 

All samples from the CLTs and lysimeters were analyzed for Cd, Cr, Se, and 

Ag. Each of these elements is regulated when foundry sand, foundry slag, fly ash, 

and bottom ash are reused in Wisconsin. In addition, Cd and Ag more readily sorb 

to soil solids and are less mobile, whereas Cr and Ag can be less sorptive and more 

mobile. The samples were analyzed by atomic adsorption (AA) spectrometry or 

inductively coupled plasma optical emission spectrometry (ICP-OES). AA was used 

earlier in the study and ICP-OES later in the study. A switch was made to ICP-OES 

to make testing more efficient. 

The AA analyses were conducted using a Varian SpectrAA-800 atomic 

adsorption (AA) spectrometer equipped with a GTA-100 graphite tube atomizer, an 

automated sample dispenser, and a Varian SpectAA-800 Data Station. Procedures 

described in USEPA Standard Methods 213.2, 218.2, 270.2, and 272.2 were 

followed for the AA analyses. The AA was calibrated using 4 standard dilutions to 

create a calibration curve. Samples were analyzed using ICP-OES following 

USEPA Method 6010B using a Perkin Elmer Optima 4300 DV ICP-OES or a 

Thermo Jarrell Ash ICAP 61E Trace Analyzer. The detection limits for the AA and 

ICP-OES analyses are in Table 2. 

Duplicate tests were conducted on each sample and samples with a relative 

standard deviation (RSD) > 5% were re-tested. Blanks were included every 10 to 

20 analyses and the calibration was verified every 10 analyses. A reagent blank 

was tested every 20 samples and a spiked sample was analyzed every 10 samples. 

21
Table 2. Limits of detection for ICP-OES and AA analysis. 

Element 

Detection Limit (μg/L) 

ICP-OES AA 

Cd 0.2 or 0.7 0.1 

Cr 1.0 or 1.7 2.0 

Se 4.0 or 10.0 2.0 

Ag 0.8 or 2.5 0.2 

Note: Detection limits for the ICP-OES analyses differ depending on the 

instrument that was used for analysis. 

22
5. RESULTS AND DISCUSSION 

5.1 Lysimeters 

5.1.1 Hydrologic Data 

Volumetric flux in each lysimeter over the 5-year monitoring period is shown 

in Fig. 4 along with precipitation data from the National Oceanic and Atmospheric 

Administration (NOAA) station in Prairie du Sac, WI (≈ 16 km from the site). The 

gap between July 2002 and June 2003 occurred due to a lapse in funding. The 

volumetric flux from each test section varies seasonally, with higher fluxes typically 

occurring in spring and summer when precipitation rates are higher and 

temperatures are above freezing. The lowest volumetric fluxes occur during winter, 

when frozen ground conditions are common. 

Volumetric fluxes from the test sections constructed with the finer grained 

materials (foundry sand - 0.09 mm/d, fly-ash-stabilized soil - 0.17 mm/d) are lower, 

on average, than the volumetric fluxes from the test sections constructed with 

coarser materials (foundry slag - 0.22 mm/d, bottom ash - 0.26 mm/d, and control 

section - 0.20 mm/d). Liquid did not appear in the collection drums from the foundry 

sand section for the first 8 months. The lower average flux and the longer time for 

leachate breakthrough from the foundry sand layer are likely due to the bentonite 

content (10%) of the foundry sand. Laboratory tests conducted by Abichou et al. 

(2002) on this foundry sand indicated that the saturated hydraulic conductivity is on 

the order of 10-8 cm/s. 

23
 24

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0

5

10

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out Precipitation

Volumetric Flux (mm/d)

Monthly Precipitation (mm/d)

Date

(a)

Foundry Sand

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Volumetric Flux (mm/d)

Date

(b)

Foundry Slag

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Volumetric Flux (mm/d)

Date

(c)

Bottom Ash

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Volumetric Flux (mm/d)

Date

(d)

Fly Ash

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Volumetric Flux (mm/d)

Date

(e)

Control

Fig. 4. Precipitation and volumetric flux from (a) foundry sand, (b) foundry slag, 

(c) bottom ash, (d) fly-ash-stabilized-soil, and (e) control sections. 
5.1.2 Metals Concentrations 

Metals concentrations in leachate from the lysimeters over the monitoring 

period are shown in Figs. 5-8. Peak concentrations observed in the lysimeters 

along with the number of pore volumes of flow to reach the peak concentration are 

summarized in Table 3. Data for the foundry sand lysimeter are not shown until 

6/2002, because too little water was discharged from the foundry sand to permit 

analysis during the earlier portion of the monitoring period. 

Cd and Cr concentrations in leachate (Figs. 5 and 6) generally are highest in 

the early portion of the monitoring period and then steadily decrease, a pattern 

referred to as “first-flush” leaching (Edil et al. 1992). Two exceptions are the Cd and 

Cr elution patterns from the leachate collected from the foundry sand lysimeter, 

which gradually climbed throughout the monitoring period (“lagged-response” 

leaching, Edil et al. 1992). Cd concentrations in the foundry sand lysimeters also 

are very low (< 5 μg/L). 

Peak concentrations of Cd and Cr in leachate from the foundry slag, bottom 

ash, and fly-ash-stabilized-soil sections are higher than the peak concentrations in 

leachate from the control section (3.4-5.2 times higher for Cd, 6.1-15.0 times higher 

for Cr). For the foundry sand section, the peak Cr concentration was also 1.8 times 

higher than the peak concentration in the control section, whereas the peak Cd 

concentration was 2.2 times lower than that for the control section. After 3 years, 

the Cd and Cr concentrations are comparable for all test sections (<5 μg/L for Cd, 

<10 μg/L for Cr). The peak Cd and Cr concentrations occurred between 0.01 and 

0.51 PVF (Table 3). 

25 
 26

0

5

10

15

20

25

30

35

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(a)

Cadmium

Foundry Sand

0

5

10

15

20

25

30

35

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(b)

Cadmium

Foundry Slag

0

5

10

15

20

25

30

35

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(c)

Cadmium

Bottom Ash

0

5

10

15

20

25

30

35

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(d)

Cadmium

Fly Ash

0

5

10

15

20

25

30

35

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(e)

Cadmium

Control

Fig. 5. Cd Concentrations in leachate from lysimeters in (a) foundry sand, (b) 

foundry slag, (c) bottom ash, (d) fly-ash-stabilized-soil, and (e) control 

sections. 
 27

0

10

20

30

40

50

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(a)

Chromium

Foundry Sand

0

10

20

30

40

50

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(b)

Chromium

Foundry Slag

0

10

20

30

40

50

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(c)

Chromium

Bottom Ash

0

10

20

30

40

50

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(d)

Chromium

Fly Ash

0

10

20

30

40

50

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(e)

Chromium

Control

Fig. 6. Cr Concentrations in leachate from lysimeters in (a) foundry sand, (b) 

foundry slag, (c) bottom ash, (d) fly-ash-stabilized-soil, and (e) control 

sections. 
 28

0

20

40

60

80

100

120

140

160

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(a)

Selenium

Foundry Sand

0

20

40

60

80

100

120

140

160

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(b)

Selenium

Foundry Slag

0

20

40

60

80

100

120

140

160

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(c)

Selenium

Bottom Ash

0

20

40

60

80

100

120

140

160

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(d)

Selenium

Fly Ash

 

0

20

40

60

80

100

120

140

160

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(e)

Selenium

Control

Fig. 7. Se Concentrations in leachate from lysimeters in (a) foundry sand, (b) 

foundry slag, (c) bottom ash, (d) fly-ash-stabilized-soil, and (e) control 

sections. 
 29

0.0

0.5

1.0

1.5

2.0

2.5

3.0

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(a)

Silver

Foundry Sand

0

2

4

6

8

10

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(b)

Silver

Foundry Slag

0

2

4

6

8

10

12

14

16

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(c)

Silver

Bottom Ash

0

20

40

60

80

100

120

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(d)

Silver

Fly Ash

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

9/1/00 9/1/01 9/1/02 9/1/03 9/1/04 9/1/05

In

Out

Concentration (μg/L)

Date

(e)

Silver

Control

Fig. 8. Ag Concentrations in leachate from lysimeters in (a) foundry sand, (b) 

foundry slag, (c) bottom ash, (d) fly-ash-stabilized-soil, and (e) control 

sections. 
The elution pattern for Se (Fig. 7) sharply contrasts the patterns for Cd and 

Cr (Figs. 5 and 6). Se concentrations are low (or are decreasing) during the first 18 

mos and much higher during the final 24 mos. The peak concentration typically is 

reached between 0.9 and 3.4 PVF, and the average PVF at the peak Se 

concentration is 2.2 times higher than the average PVF at the peak concentration 

for the other elements studied. The exception is the foundry sand section, where no 

distinct peak concentration occurred and only 0.05 PVF was transmitted. Peak Se 

concentrations from each section were similar (89-151 μg/L), although the fly-ashstabilized-soil test section typically had lower Se concentrations than the other test 

sections throughout the monitoring period. At the end of the monitoring period, Se 

concentrations from all sections were comparable (~80 μg/L). The one exception is 

the Se concentration in the leachate from the inner lysimeter in the fly-ashstabilized-soil section, which dropped below detection limits (<10 μg/L) after 3 

years. 

A possible explanation for the elevated Se concentrations in the latter 

portion of the monitoring period is that another material in the pavement structure is 

eluting Se. The similarity of the Se elution patterns and concentrations in leachate 

from each of the test sections during the latter portion of the monitoring period is 

consistent with this hypothesis. All five test sections used the same base course 

material (recycled asphalt and crushed limestone), which could be the source of Se. 

Alternatively, changing redox conditions may be occurring, resulting in 

transformation of Se(IV) to Se(VI). Se(IV) is cationic, more strongly adsorbed by 

soil solids, and less mobile, whereas Se(VI) forms anionic complexes that are 

weakly sorbed and more mobile. However, no tests were conducted to identify the 

30
Se species present in leachate, and the redox conditions present in the field are 

also unknown. 

Ag followed a first-flush elution pattern for the foundry slag, bottom ash, and 

control sections, with concentrations beginning to drop within 18 mos and 0.5 PVF 

and decreasing to less than 3 μg/L during the final two years of the monitoring 

period. The Ag elution pattern from the foundry sand section was not defined 

because only one sample had a concentration greater than the detection limit (2.5 

μg/L, July 2003). 

The two lysimeters in the fly-ash-stabilized-soil section yielded remarkably 

different Ag elution patterns. Ag concentrations in leachate from the outer lysimeter 

never exceeded 5 μg/L and followed a first-flush pattern. In contrast, Ag 

concentrations in the inner lysimeter increased to over 100 μg/L after 3 yr, and 

remained above 20 μg/L for the remainder of the monitoring period. The peak Ag 

concentration in the leachate from the inner lysimeter in the fly-ash-stabilized soil 

section occurred after 1.9 PVF. 

Peak concentrations in each test section constructed with byproducts were 

divided by peak concentrations from the control section to define normalized peak 

concentrations. The normalized concentrations are summarized in Table 3. Three 

of the sixteen cases (foundry sand – Cd and Ag; fly-ash-stabilized soil – Se) have 

normalized peak concentrations less than unity (i.e., metals eluted at a lower peak 

concentration from the byproducts sections than from the control section). In all 

other cases, the normalized peak concentrations are greater than unity. The 

normalized peak concentrations typically are highest for Cr and lowest for Se, and 

tend to be lower for the foundry sand relative to the other byproducts. 

31
Table 3. Peak Cd, Cr, Se and Ag concentrations found in the leachate from lysimeter tests on foundry sand, fo

fly-ash-stabilized soil, and crushed rock (control), along with the PVF to reach the peak concentration. 

Material 

Cd Cr Se 

Peak 

Lysimeter 

Conc. 

(μg/L) 

Normalized 

Conc. 

PVF to 

Peak 

Conc. 

Peak 

Lysimeter 

Conc. 

(μg/L) 

Normalized 

Conc. 

PVF 

to 

Peak 

Conc. 

Peak 

Lysimeter 

Conc. 

(μg/L) 

Normalized 

Conc. 

PVF to 

Peak 

Conc. 

Peak 

Lysimet

Conc. 

(μg/L) 

Foundry 

Sand 2.8 0.45 0.16 6.1 1.85 0.01 105 1.05 0.05 2.6 

Foundry 

Slag 32.1 5.18 0.29 49.6 15.03 0.17 151 1.51 0.87 8.2 

Bottom 

Ash 21.2 3.42 0.17 32.1 9.73 0.33 141 1.41 0.98 15.2 

Fly-AshStabilized 32.1 5.18 0.01 20.2 6.12 0.26 89 0.89 3.37 96.4 

Soil 

Control 6.2 1.00 0.51 3.3 1.00 0.44 100 1.00 1.23 3.9 
5.2 Comparison of Peak Concentrations in Lysimeters and WLTs 

Cd, Cr, Se, and Ag concentrations in the leachate from the WLTs are 

summarized in Table 4 along with peak concentrations from the lysimeters and CLTs. 

Concentrations from the WLTs are below detection limits for 8 of the 16 cases, whereas 

peak concentrations in the leachate collected in the lysimeters are always above 

detection limits (Table 4). A graph of peak concentrations from the lysimeters vs. 

corresponding concentrations from the WLTs is shown in Fig. 9. Peak concentrations 

from the lysimeters generally are higher than those from the WLTs; in only one case is 

the peak concentration from the WLT higher than the peak concentration from the 

lysimeters (Cr from fly-ash-stabilized soil). 

Differences in liquid-solid ratio may be responsible for the disparity between the 

peak field concentrations and the concentrations from the WLTs. A dilution calculation 

based on the PVF at the peak lysimeter concentration indicates that the L-S ratio in the 

field (at peak concentration) ranges between 0.5-2.2, whereas a L-S ratio of 20 was 

used in the WLTs (i.e., 9.1 – 40 times larger than the L-S ratio at peak concentration in 

the field). Many of the peak field concentrations are within a factor of 9-40 of the 

concentrations measured in the WLTs. Differences in pH and redox conditions may also 

have contributed to the disparity, but cannot be quantified with the data that are 

available. 

33
Table 4. Cd, Cr, Se, and Ag concentrations in leachate from lysimeters, CLTs, and WLTs on f

foundry slag, bottom ash, and fly-ash-stabilized soil. 

Material Peak Lysimeter Conc. (

μg/L) Peak CLT Conc. (

μg/L) WLT pH and Conce

Cd Cr Se Ag Cd Cr Se Ag Cd Cr Se 

Foundry Sand 2.8 6.1 105 2.6 32.9 <1.7 <4.0 6.7 0.3 <1.0 <10 

Foundry Slag 32.1 49.6 151 8.2 <0.7 6530 <4.0 16.8 0.2 <1.0 <10 

Bottom Ash 21.2 32.1 141 15.2 10.3 961 24.1 4.4 <0.2 1.1 32.5 

Fly-AshStabilized Soil 32.1 20.2 89.0 96.4 4.6 62.9 32.4 5.8 0.6 46 16.2 

Fly Ash Alone - - - - - - - - 0.7 95 26 

Note: Hyphen indicates that test was not conducted. <X.Y indicates concentration is below the 

(X.Y 

μg/L). 
Peak Lysimeter Concentration ( 

μg/L) 

1000 

100

10

1

0.1 

Cd 

Cr 

Se 

Ag 

ions 

bel i imi i

i ion limi

< 

< 

< 

< 

< 

< 

< 

< 

1:1 

1000:1 100:1 10:1 

Solid symbols correspond to WLT concentrat

ow the detect on l t. WLT concentrat ons shown 

for sol d symbols are the detect t. 

0.1 1 10 100 1000

WLT Concentration (μg/L)

Fig. 9. Comparison peak concentrations found in the leachate from lysimeter tests to 

Cd, Cr, Se, and Ag concentrations from WLTs. 

35
5.3 Comparison of Elution in Lysimeters and CLTs 

Peak concentrations from the CLTs are summarized in Table 5. A comparison of 

peak concentrations from the lysimeters and peak concentrations from the CLTs is 

shown in Fig. 10. Many of the peak lysimeter and CLT concentrations differ by less than 

a factor of 10, but some differ by a factor as large as 131. Peak Se and Cd 

concentrations in the lysimeters tend to be higher than those from the CLTs, Ag 

concentrations from the lysimeters and the CLTs tended to be more comparable, and 

peak Cr concentrations from the lysimeters tend to be lower than those form the CLTs. 

Elution curves for Cd from the test sections and CLTs are shown in Fig. 11. 

Similar elution patterns for Cd were obtained in the field and the CLTs for the test 

sections constructed with foundry sand (delayed leaching) and fly-ash-stabilized soil 

(first-flush leaching), except for two outlier points for the CLT on foundry sand. In fact, 

for the fly-ash-stabilized soil, the Cd elution patterns in the field and CLTs are nearly 

identical. In contrast, elution of Cd from the foundry slag and bottom ash test sections 

followed a first-flush pattern, whereas the CLTs yielded concentrations below the 

detection limits over the same range of PVF. The pH was not measured during the field 

tests. However, pH at the peak Cd concentration in the leachate from the other CLTs 

was slightly basic, between 8.4 and 8.6. 

Elution curves for Cr from the test sections and CLTs are shown in Fig. 12. The 

elution curves from the CLTs on foundry slag, bottom ash, and fly-ash-stabilized-soil 

exhibit a similar pattern as those from the field, although the peak Cr concentrations 

from the CLTs were 3.1 to 131.7 times larger than those in the field. In contrast, for 

foundry sand, Cr concentrations from the CLT were always less than the detection limit 

(1.7 μg/L), whereas concentrations from the lysimeter were as high as 6.1 μg/L. 

However, only a small volume of water was discharged from the foundry sand test 

section (< 0.23 PVF), and all of the CLT data are for PVF > 0.14. 

36
Table 5. Peak Cd, Cr, Se, and Ag concentrations, leachate pH, and PVF to peak concentration from CLT

foundry slag, bottom ash, and fly-ash-stabilized soil. 

Material 

Cd Cr Se 

Peak 

CLT 

Conc. 

(μg/L) 

pH at 

Peak 

Conc. 

PVF to 

Peak 

Conc. 

Peak 

CLT 

Conc. 

(μg/L) 

pH at 

Peak 

Conc. 

PVF to 

Peak 

Conc. 

Peak 

CLT 

Conc. 

(μg/L) 

pH at 

Peak 

Conc. 

PVF to 

Peak 

Conc. 

Peak 

CLT 

Conc. 

(μg/L) 

Foundry 

Sand 32.9 8.4 0.1 <1.7 - - <4 - - 7.0 

Foundry 

Slag <0.7 - - 6530 7.4 0.6 <4 - - 16.8 

Bottom 

Ash 10.3 8.5 22.9 961 7.7 0.7 24 9.1 16.5 4.4 

Fly-AshStabilized 4.6 8.6 0.8 62.9 8.6 0.8 32.4 8.6 0.3 5.8 

Soil 
10,000 

1,000 

100

10

1

0.1 

Cd 

Cr 

Se 

Ag 

l

i

l imi

i

li

ion limi

< 

< 

< 

< 

100:1 10:1 1:1 

1:10 

1:100 

Solid symbo s correspond to 

WLT concentrat ons 

be ow the detection l t. 

WLT concentrat ons shown 

for so d symbols are 

the detect t. 

0.1 1 10 100 1,000 10,000

Peak CLT Concentration (μg/L)

Fig. 10. Comparison of peak Cd, Cr, Se, and Ag concentrations in leachate from lysimeters to 

peak CLT concentrations. Peak Lysimeter Concentration ( 

μg/L) 

38
 39

0

5

10

15

20

25

30

35

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(a)

Cadmium

Foundry Sand

WLT = 0.3 μg/L

0

5

10

15

20

25

30

35

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(b)

Cadmium

Foundry Slag

WLT = 0.2 μg/L

0

5

10

15

20

25

30

35

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(c)

Cadmium

Bottom Ash

WLT = <0.2 μg/L

Points on axis represent samples below detection limit

0

5

10

15

20

25

30

35

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(d)

Cadmium

Fly Ash

WLT = 0.6 μg/L

Fig. 11. Cd elution curves from CLTs and lysimeters: (a) foundry sand, (b) foundry slag, (c) 

bottom ash, and (d) fly ash stabilized soil. 
 40

0.1

1

10

100

1000

10000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(a)

Chromium

Foundry Sand

WLT = <1.0 μg/L

Points on axis represent samples below detection limit

0.1

1

10

100

1000

10000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(b)

Chromium

Foundry Slag

WLT = 0.2 μg/L

Points on axis represent samples below detection limit

0.1

1

10

100

1000

10000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out) CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(c)

Chromium

Bottom Ash

WLT = 1.1 μg/L

 

0.1

1

10

100

1000

10000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(d)

Chromium

Fly Ash

WLT = 46 μg/L

Fig. 12. Cr elution curves from CLTs and lysimeters: (a) foundry sand, (b) foundry slag, (c) 

bottom ash, and (d) fly ash stabilized soil. 
Elution curves for Se from the test sections and CLTs are shown in Fig. 13. Similar 

curves were obtained from the CLTs and the field only for the fly-ash-stabilized-soil. For the 

other materials, Se concentrations from the CLTs were nearly always less than the detection 

limit (4.0 μg/L), whereas peak concentrations of Se in the field ranged from 89 μg/L to 151 μg/L. 

The large discrepancy between Se concentrations from the CLTs and those measured in the 

field also supports the hypothesis, proffered in Section 5.1.2, that another material in the 

pavement structure, which was not tested in the CLTs, is the source of Se. 

Elution curves for Ag from the test sections and CLTs are shown in Fig. 14. Similar 

elution patterns were obtained from the field and CLTs for bottom ash and fly-ash-stabilized soil. 

For the fly-ash-stabilized soil, however, Ag concentrations increased in one lysimeter and 

decreased in the other during the latter portion of the monitoring period, whereas the CLT 

concentrations decreased slightly over the same range of PVF. Concentrations of Ag from the 

CLT on foundry sand tended to be much higher than those measured in the field, which 

generally were below the detection limit (2.5 μg/L). However, the one sample from the foundry 

sand lysimeter that was above the detection limit (2.6 μg/L) was within the range of 

concentrations obtained from the CLT (1.2-6.7 μg/L). Concentrations of Ag from the foundry 

slag test section varied considerably and intermittently, ranging from below the detection limit up 

to 8.2 μg/L. A similar variation in concentration of Ag was observed from the CLT on foundry 

slag. 

41
 42

0

20

40

60

80

100

120

140

160

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(a)

Selenium

Foundry Sand

WLT = <10 μg/L

Points on axis represent samples below detection limit

0

20

40

60

80

100

120

140

160

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(b)

Selenium

Foundry Slag

WLT = <10 μg/L

Points on axis represent samples below detection limit

0

20

40

60

80

100

120

140

160

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(c)

Selenium

Bottom Ash

WLT = 32.2 μg/L

Points on axis represent samples below detection limit

 

0

20

40

60

80

100

120

140

160

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(d)

Selenium

Fly Ash

WLT = 16.2 μg/L

Fig. 13. Se elution curves from CLTs and lysimeters: (a) foundry sand, (b) foundry slag, (c) 

bottom ash, and (d) fly ash stabilized soil.
 43

0.1

1

10

100

1000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(a)

Silver

Foundry Sand

WLT = <2.5 μg/L

Points on axis represent samples below detection limit

0.1

1

10

100

1000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(b)

Silver

Foundry Slag

WLT = <2.5 μg/L

Points on axis represent samples below detection limit

0.1

1

10

100

1000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(c)

Silver

Bottom Ash

WLT = <2.5 μg/L

Points on axis represent samples below detection limit

 

0.1

1

10

100

1000

0

2

4

6

8

10

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Column Leach Test

Lysimeter (In)

Lysimeter (Out)

CLT pH

Concentration (μg/L)

CLT pH

Pore Volumes of Flow

(d)

Silver

Fly Ash

WLT = 1.8 μg/L

Fig. 14. Ag elution curves from CLTs and lysimeters: (a) foundry sand, (b) foundry slag, (c) 

bottom ash, and (d) fly ash stabilized soil.
6. IMPLICATIONS FOR GROUNDWATER QUALITY 

Groundwater quality standards applicable to the field site are defined in Section 

NR 140 (Groundwater Quality) of Wisconsin Administrative Code. The Wisconsin 

standards are the same as or lower than USEPA MCLs. 

A comparison of the Wisconsin standards for Cd, Cr, Se, and Ag and peak 

concentrations from the test sections is in Table 6. Cd concentrations in the leachate 

from the foundry slag, bottom ash, and control sections exceeded the Wisconsin 

standard (5 μg/L) by a factor of 1.2-6.4 for the first 18 mos of the field test. However, in 

all cases, the Cd concentrations were below the Wisconsin standard after 16 mos and 

0.6 PVF. Se concentrations exceeded the Wisconsin standard (50 μg/L) for all test 

sections by a factor of 1.8 to 3.0. Moreover, in all cases except for the fly-ash-stabilized 

soil, the Se concentration increased and then leveled off at a concentration exceeding 

the Wisconsin standard over the last 24 months of monitoring. 

In contrast to Cd and Se, leachate concentrations exceeding the Wisconsin 

standard for Ag (50 μg/L) were only observed in the fly-ash-stabilized soil section (peak 

= 96 μg/L). Ag concentrations of this magnitude were only recorded in one lysimeter in 

the fly-ash-stabilized soil section, and the concentration in this lysimeter fluctuated 

between 19 and 113 μg/L over the last 24 months of the monitoring period. None of the 

test sections had Cr concentrations exceeding the Wisconsin standard (100 μg/L). 

Leachate collected in the lysimeters is representative of pore fluid at the bottom 

of the pavement profile and represents water reaching groundwater only if the 

44
Table 6. Peak lysimeter concentrations and estimated concentrations after 1 m and 5 m of migration from the 

layers based on analysis reported in Bin Shafique et al. (2002). 

Material Peak Lysimeter Conc. (

μg/L) Conc. after 1 m migration (

μg/L) Conc. after 5 m mig

Cd Cr Se Ag Cd Cr Se Ag Cd Cr 

Foundry 

Sand 2.8 6.1 105 2.6 0.6 1.2 21.0 0.5 0.3 0.6 

Foundry Slag 32.1 49.6 151 8.2 6.4 9.9 30.2 1.6 3.2 5.0 

Bottom Ash 21.2 32.1 141 15.2 4.2 6.4 28.2 3.0 2.1 3.2 

Fly-AshStabilizedSoil 32.1 20.2 89 96.4 6.4 4.0 17.8 19.3 3.2 2.0 

Wisconsin 

Standard 5 100 50 50 5 100 50 50 5 100 
groundwater table is at the base of the pavement profile. In many roadways, the water 

table will be deeper. Processes such as sorption, diffusion, dispersion, and dilution 

occurring in soils between the base of the pavement and the groundwater table will 

result in lower concentrations by the time the groundwater table is reached. 

Bin Shafique et al. (2002) conducted a modeling study to simulate the transport 

of contaminants from working platforms constructed with byproducts to the groundwater 

table using a variably saturated model of flow and transport that was validated using 

data from field lysimeter studies. Their findings indicate that the maximum concentration 

1 m below the pavement layer is approximately 20% of the peak concentration at base 

of the byproduct layer. At 5 m, the maximum concentration is approximately 10% of the 

peak concentration at the base of the byproduct layer. 

Concentrations at the groundwater table obtained by applying these “dilution” 

factors are summarized in Table 6. In all cases, the estimated concentrations of Cd, Cr, 

Se, and Ag at the water table are below Wisconsin standards when the groundwater 

table is at least 5 m below the byproduct layer. For cases where the groundwater table 

is 1 m below the byproduct layer, the Wisconsin standards for Cd, Cr, Se, and Ag would 

be met for the foundry sand and bottom ash sections. However, for the test sections 

with foundry slag and fly-ash-stabilized soil, the Cd concentrations are 1.3 times the 

Wisconsin standard, whereas the Cr, Se, and Ag concentrations are at least 40% lower 

than the Wisconsin standards. 

46
7. SUMMARY AND CONCLUSIONS 

Leaching data from five test sections constructed along a stretch of Wisconsin 

State Highway 60 near Lodi, WI have been presented and discussed in this report. Four 

of these test sections were constructed with a layer of industrial byproducts (foundry 

sand, foundry slag, bottom ash, or fly-ash-stabilized soil) between the existing soft 

subgrade and the base course layer. One of the test sections was a control and was 

constructed with a layer of crushed dolostone instead of industrial byproducts. All four 

byproducts met the criteria in the Wisconsin Administrative Code for re-use in confined 

geotechnical fills. 

Leachate draining from the test sections was collected in pan lysimeters and 

analyzed for concentrations of Cd, Cr, Se, and Ag. Batch water leach tests (WLTs) and 

column leach tests (CLTs) were also conducted on each of the byproducts using typical 

procedures used to evaluate the suitability of byproducts for use in earthwork 

applications. Concentrations of Cd, Cr, Se, and Ag from the WLTs and CLTs were 

compared with concentrations measured in the leachate collected in the field and with 

groundwater quality standards in the Wisconsin Administrative Code. 

Leachate collected in the lysimeters commonly had Cd, Se, and Ag 

concentrations exceeding Wisconsin groundwater quality standards. However, 

application of dilution factors to account for the reduction in concentration expected 

between the bottom of the pavement structure and the groundwater table showed that 

concentrations exceeding groundwater quality standards would not occur if the 

byproducts layer is at least 5 m above the groundwater table. For a separation distance 

of 1 m, only Cd would modestly (30%) exceed the groundwater quality standard directly 

beneath the centerline of the pavement. 

Comparison of peak concentrations from the lysimeters and concentrations 

obtained from the WLTs indicated that WLTs generally underestimate peak field 

47
concentrations by a factor between 4-160, but in most cases the factor is less than 55. 

Dilution caused by the large liquid-solid ratio used in the WLTs is partly responsible for 

the disparity between the field and WLT concentrations, although differences in pH and 

redox conditions may have been important as well. 

Peak concentrations from the CLTs were closer to peak concentrations in the 

field than the concentrations from the WLTs. Peak concentrations from the CLTs 

typically were within a factor of 10 of peak concentrations from the CLTs, although the 

peak CLT concentrations were as much as 45 times higher and 131 times lower than the 

peak field concentrations. The elution patterns in the field and the CLTs (first flush or 

delayed response) generally were similar, although the magnitude of the concentrations 

differed. An exception is the fly-ash-stabilized soil, for which both concentrations and 

elution patterns from the field and the CLTs were similar. 

An unusual rise in Se concentration was observed in all of the field lysimeters 

(including the control) later in the monitoring period, but in none of the CLTs. The 

presence of elevated Se concentrations in all lysimeters (and at similar concentration) 

suggests that Se is leaching from another source within the pavement structure, and not 

the byproducts. One potential source is the crushed rock or recycled asphalt in the base 

course layer. This observation illustrates that leaching from pavement structures is not 

limited to byproducts layers, and that other potential sources of contaminants should be 

considered when evaluating impacts to groundwater attributed to the use of industrial 

byproducts in highway construction. 

48
8. ACKNOWLEDGEMENTS 

Financial support for this study was provided by the Recycled Materials Research 

Center through the Wisconsin Department of Transportation, the Wisconsin Department 

of Natural Resources Waste Reduction and Recycling Demonstration Grant Program, 

and Alliant Energy. However, the findings and inferences that have been reported are 

those solely of the authors. Endorsement by the sponsors is not implied and should not 

be assumed. 

49
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Gutierrez, B., Pazos, C., and Coca, J. (1993). “Characterization and Leaching of Coal 

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51
Proctor, D. M., Fehling, K. A., Shay, E. C., Wittenborn, J. L., Green, J. J., Avent, C., 

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52
APPENDIX

COLUMN LEACH TEST RESULTS

53
Table A2.1 pH, Cd, Cr, Se, and Ag concentrations from CLT on bottom ash. 

Bottom Ash Column Leach Test Results 

Est PVF pH Influent pH Cd 

Concentration (μg/L) 

Cr Se Ag 

0.0 

0.1 7.2 6.8 

0.2 7.3 6.8 ND 292 ND ND 

0.2 7.5 6.8 

0.4 7.5 6.8 ND 625 ND 2.4 

0.4 7.6 6.8 

0.5 7.6 6.8 ND 684 7.6 1.6 

0.5 7.6 6.8 

0.6 7.7 6.8 ND 730 10.5 1 

0.7 7.7 6.8 

0.7 7.7 6.8 ND 961 17.2 1.4 

0.8 7.6 6.8 

0.9 7.6 6.8 

0.9 7.7 6.8 ND 863 14.9 1.5 

1.4 7.6 6.8 ND 365 ND ND 

1.5 7.8 6.8 

1.6 8.0 6.8 

1.6 8.0 6.8 ND 324 ND 2.6 

2.2 8.1 6.8 ND 311 ND 2.4 

2.4 8.0 6.8 ND 232 ND 1.8 

2.7 8.3 6.9 ND 188 ND 2.5 

2.8 8.1 6.9 

3.1 8.4 6.9 ND 131 ND 2.4 

3.4 8.4 6.9 

3.6 8.4 6.9 ND 67.3 ND 0.87 

3.7 8.2 6.9 ND 45.7 ND 1.2 

4.0 8.3 6.9 

4.2 8.4 6.9 ND 7.2 ND ND 

4.6 8.5 6.9 

5.1 8.5 6.9 ND 2.7 ND 2.5 

5.6 8.6 6.9 

6.0 8.2 6.9 

6.4 8.4 6.9 

6.9 8.5 6.7 ND ND ND 4.4 

7.3 8.7 6.6 

7.9 8.7 6.7 ND 3 ND 2.7 

8.3 8.8 6.7 

8.7 8.7 6.8 ND 2 ND 3.4 

9.2 8.3 6.8 

9.6 8.4 6.7 ND 2.8 ND 3.4 

10.2 8.5 6.7 

10.6 8.6 6.7 ND 2 ND 2.4 

11.4 8.6 6.7 

12.2 8.8 6.7 ND 1.7 ND 2 

12.7 8.9 6.7 ND 0 ND 3.6 

13.3 8.9 6.7 

54
Est PVF pH Influent pH Cd 

Concentration (μg/L) 

Cr Se Ag 

14.6 9.0 6.7 ND 1.9 ND 0.86 

15.2 9.0 6.7 ND 2.8 ND 2.9 

15.7 9.1 6.6 

16.5 9.1 6.6 ND 2.8 24.1 3.5 

17.1 9.0 6.6 

17.8 8.8 6.8 ND 3.9 ND 1.5 

18.6 8.8 6.8 ND ND ND ND 

19.2 8.8 6.8 ND ND ND 1.7 

20.0 8.6 6.8 ND 2.1 ND 2.2 

21.0 8.6 6.8 ND 3.2 ND ND 

22.0 8.6 6.8 ND 3.7 ND 1.6 

22.9 8.5 6.8 10.3 5.3 ND 1.4 

23.7 8.5 6.8 ND 2.1 ND 1.9 

24.5 8.5 6.8 ND ND ND 2.2 

25.1 8.4 7.0 ND ND ND 1.1 

26.0 8.4 6.9 ND ND ND 2.1 

26.9 8.4 6.9 ND ND ND 1.6 

27.8 8.6 6.9 ND ND ND 0.9 

28.2 9.0 6.9 ND ND ND ND 

28.5 8.6 6.9 ND 6.5 ND 1.3 

28.6 8.4 6.9 ND 6.3 ND 1.8 

28.6 8.6 6.9 ND 5.1 ND 0.92 

28.9 9.2 6.9 ND 2.3 ND 1.3 

29.7 9.3 6.9 ND 10.2 22 2.5 

55
Table A2.2 Cd, Cr, Se, and Ag concentrations from CLT on fly ash. 

Fly Ash Column Leach Test Results 

Concentration (mg/L) 

PVF Cd Cr Se Ag 

0.27338 3.76 60.24 32.38 5.84 

0.7605 4.63 62.93 30.07 5.35 

1.24 2.99 42.64 30.41 5.39 

1.8593 2.81 42.23 24.62 3.95 

2.5902 1.37 17.23 15.74 3.61 

3.3084 1.3 15.13 10.17 3.54 

4.0036 2.08 14.45 8.09 1.8 

4.9034 1.07 7.23 3.86 1.86 

6.0311 0.37 14.26 2.76 0.5 

7.2444 0.39 3.21 2.62 0.4 

8.3886 0.73 3.45 0.96 0.33 

9.5244 0.34 2.95 0.73 0.61 

10.719 0.63 0.28 0.57 0.28 

11.887 0.32 0.32 

56
Table A2.3 pH, Cd, Cr, Se, and Ag concentrations from CLT on foundry sand. 

Foundry Sand Column Leach Test Results 

Est PVF pH Concentration (μg/L) 

Cd Cr Se Ag 

0.14 8.4 32.9 ND ND 3.1 

0.21 8.5 1.2 ND ND 1.7 

0.32 8.5 1.2 ND ND 4.4 

0.39 8.5 1.4 ND ND 1.7 

0.59 8.4 ND ND ND ND 

0.79 8.4 ND ND ND 2 

1.03 8.4 ND ND ND 4.2 

1.11 8.4 ND ND ND 2.7 

1.25 8.5 ND ND ND 6.1 

1.35 8.6 ND ND ND ND 

1.41 8.7 ND ND ND ND 

1.58 8.1 9.2 ND ND 1.2 

1.58 8.5 ND ND ND 6.7 

57 
Table A2.4 pH, Cd, Cr, Se, and Ag concentrations from CLT on foundry slag. 

Foundry Slag Column Leach Test Results 

Est PVF pH Influent pH Cd 

Concentration (μg/L) 

Cr Se Ag 

0.0 

0.0 7.1 6.84 

0.2 7.1 6.84 ND 1790 ND ND 

0.3 7.4 6.84 

0.3 7.3 6.84 ND 3740 ND ND 

0.4 7.3 6.84 

0.5 7.3 6.84 ND 5460 ND ND 

0.5 7.3 6.84 

0.6 7.4 6.84 ND 6530 ND ND 

0.7 7.5 6.84 

0.8 7.5 6.84 ND 5830 ND ND 

0.9 7.5 6.84 

0.9 7.5 6.84 ND 4690 ND ND 

1.4 8.6 6.84 ND 3220 ND 2.4 

1.5 8.5 6.84 

1.5 8.7 6.84 ND 2250 ND 2 

1.6 8.9 6.84 ND 2050 ND 1.6 

2.3 9.2 6.84 

2.4 9.3 6.84 ND 1520 ND ND 

2.8 9.4 6.89 

2.9 9.4 6.89 ND 1060 ND ND 

3.2 9.5 6.87 

3.6 9.6 6.88 ND 640 ND ND 

3.8 9.5 6.9 

3.9 9.2 6.89 ND 525 ND ND 

4.1 9.5 6.91 ND 553 ND ND 

4.4 9.6 6.93 

4.8 9.6 6.93 ND 482 ND ND 

5.3 9.6 6.9 ND 246 ND ND 

5.8 9.7 6.85 ND 165 ND ND 

6.2 9.3 6.93 

6.7 9.4 6.92 ND 161 ND ND 

7.2 9.6 6.68 

7.6 9.7 6.63 ND 118 ND 1.3 

8.2 9.6 6.67 

8.6 9.7 6.67 ND 113 ND ND 

9.1 9.7 6.79 

9.6 9.7 6.78 ND 130 ND ND 

10.0 9.7 6.72 

10.5 9.7 6.7 ND 91.1 ND ND 

11.0 9.8 6.68 

11.8 9.8 6.67 ND 93 ND ND 

12.6 9.8 6.7 ND 85.7 ND ND 

13.1 9.8 6.67 

13.8 9.8 6.66 ND 55.7 ND ND 

14.4 9.8 6.66 ND 52.6 ND ND 

58
Est PVF pH Influent pH Cd 

Concentration (μg/L) 

Cr Se Ag 

15.7 9.8 6.67 ND 71.6 ND ND 

16.3 9.8 6.64 ND 77.7 ND ND 

17.0 9.9 6.61 

17.6 9.7 6.64 ND 38.3 ND ND 

18.4 9.6 6.83 ND 90 ND ND 

19.2 9.7 6.83 

19.8 9.7 6.83 ND 31.3 ND ND 

20.7 9.7 6.83 ND 45 ND ND 

21.7 9.5 6.83 ND 57.2 ND ND 

22.7 9.4 6.83 ND 52.2 ND ND 

23.6 9.6 6.83 ND 70.7 ND ND 

24.2 9.6 6.83 

25.0 9.6 6.83 

25.6 9.6 6.95 ND 37.9 ND ND 

26.5 9.5 6.88 ND 37.6 ND ND 

27.5 9.5 6.9 ND 46.1 ND ND 

28.5 9.4 6.9 ND 37.5 ND ND 

28.7 8.6 6.94 ND 17.1 ND 16.8 

29.0 8.8 6.94 ND 95 ND ND 

29.1 8.5 6.94 ND 89.9 ND ND 

29.1 8.5 6.94 ND 91.5 ND ND 

29.6 9.0 6.87 ND 29.1 ND ND 

30.3 9.4 6.87 ND 177 ND ND 

59
 60

0

2

4

6

8

10

12

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Foundry Sand

CLT Effluent pH

Pore Volumes of Flow

0

2

4

6

8

10

12

0 5 10 15 20

Foundry Slag

CLT Effluent pH

Pore Volumes of Flow

0

2

4

6

8

10

12

0 510 15 20

Bottom Ash

CLT Effluent pH

Pore Volumes of Flow

Fig. A2.1 pH versus PVF for CLTs on foundry slag, foundry sand, and bottom ash.
WATER LEACH TEST RESULTS 

61
Table A3.1 pH, Cd, Cr, Se, Ag, Fe, and Pb concentrations from WLTs on 

foundry sand, foundry slag, bottom ash, fly ash alone, and fly-ashstabilized soil. 

Material WLT pH and Concentration (μg/L) 

Cd Cr Se Ag Fe Pb pH 

Foundry Sand 0.3 <1.0 <10 <2.5 430 8 9.0 

Foundry Slag 0.2 <1.0 <10 <2.5 48.3 12 10.7 

Bottom Ash <0.2 1.1 32.5 <2.5 - - 10.3 

Fly-Ash-Stabilized 

Soil 0.6 46 16.2 1.8 - - 11.0 

Fly Ash Alone 0.7 95 26 2.2 - - 11.8 

62
MONITORING WELLS

63
6.5 ft 

Top Soil: 6 in 

Bentonite Seal: 1 ft 3 ft 

10-Slot PVC Pipe 

Screen: 5 ft 

Locking Cap 

Well Profile: 

Well ID: BA #1 

INSERT 

1/16/04 

Borehole Diameter: 4 in 

2 in 

Sand Filter Pack: 

PVC Riser Pipe: 

Well Location: 20 ft South of STH 60, 50 ft West of Dettman Rd 

UTM Coordinates: 

Installation Date: 

Pipe Diameter: 

64
8 ft 

Bentonite Seal: 1 ft 3 ft 

10-Slot PVC Pipe 

Screen: 5 ft 

Locking Cap 

Well Profile: 

Well ID: BA #2 

INSERT 

10/27/03 

2 in 

Sand Filter Pack: 

Top Soil: 1 ft 

PVC Riser Pipe: 

Well Location: 15 ft North of STH 60, 50 ft West of Dettman Rd 

UTM Coordinates: 

Installation Date: 

Pipe Diameter: 

Borehole Diameter: 4 in 

65
6.5 ft 

Top Soil: 6 in 

Bentonite Seal: 1 ft 3 ft 

10-Slot PVC Pipe 

Screen: 5 ft 

Locking Cap 

Well Profile: 

Well ID: Control #1 

INSERT 

1/16/04 

Borehole Diameter: 4 in 

2 in 

Sand Filter Pack: 

PVC Riser Pipe: 

Well Location: 20 ft South of STH 60, 50 ft East of Dettman Rd 

UTM Coordinates: 

Installation Date: 

Pipe Diameter: 

66
8 ft 

Bentonite Seal: 1 ft 3 ft 

10-Slot PVC Pipe 

Screen: 5 ft 

Locking Cap 

Well Profile: 

Well ID: Control #2 

INSERT 

10/27/03 

2 in 

Sand Filter Pack: 

Top Soil: 1 ft 

PVC Riser Pipe: 

Well Location: 20 ft North of STH 60, 50 ft East of Dettman Rd 

UTM Coordinates: 

Installation Date: 

Pipe Diameter: 

Borehole Diameter: 4 in 

67
6.5 ft 

Top Soil: 6 in 

Bentonite Seal: 1 ft 4 ft 

10-Slot PVC Pipe 

Screen: 5 ft 

Locking Cap 

Well Profile: 

Well ID: FA #1 

20 ft South of STH 60, 350 ft East of Dettman Rd 

INSERT 

1/16/04 

2 in 

Sand Filter Pack: 

PVC Riser Pipe: 

Well Location: 

UTM Coordinates: 

Installation Date: 

Pipe Diameter: 

Borehole Diameter: 4 in 

68
8 ft 

Bentonite Seal: 1 ft 4 ft 

10-Slot PVC Pipe 

Screen: 5 ft 

Locking Cap 

Well Profile: 

Well ID: FA #2 

INSERT 

10/27/03 

2 in 

Sand Filter Pack: 

Top Soil: 1 ft 

PVC Riser Pipe: 

Well Location: 20 ft North of STH 60, 350 ft East of Dettman Rd 

UTM Coordinates: 

Installation Date: 

Pipe Diameter: 

Borehole Diameter: 4 in 

69