Geology, Hydrology, and Water Quality of 

the Glacial Drift Aquifer in the Vicinity of 

the Nelson Landfill near Yorkville, Illinois

By Robert T. Kay

In cooperation with the U.S. Environmental Protection Agency and 

the United City of Yorkville, Illinois

Open-File Report 2006–1045

U.S. Department of the Interior

U.S. Geological Survey

U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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iii

Contents

Abstract...........................................................................................................................................................1

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

Purpose and Scope ..............................................................................................................................3

Site History.............................................................................................................................................3

STUDY METHODS..........................................................................................................................................6

GEOLOGY.........................................................................................................................................................9

HYDROLOGY..................................................................................................................................................14

WATER QUALITY ..........................................................................................................................................17

Field Measurements...........................................................................................................................17

Major Ions............................................................................................................................................19

Nitrogen Compounds .........................................................................................................................23

Organic Compounds...........................................................................................................................23

Metals and Cyanide............................................................................................................................23

SUMMARY AND CONCLUSIONS ..............................................................................................................31

Literature Cited.............................................................................................................................................31

Figures

1–4. Maps showing—

1. Thickness of glacial drift deposits and location of the Nelson Landfill site and 

the Newark Bedrock Valley in Kendall County, Illinois.............................................................2

2. Location of the Nelson Landfill site, Yorkville, Illinois...............................................................4

3. Ground-water sampling locations and line of geologic section in the vicinity of 

the Nelson Landfill site...................................................................................................................5

4. Surficial geology of Kendall County, Illinois .............................................................................10

5. Diagram showing hydrogeologic section A-A’ in the vicinity of the Nelson Landfill 

site ...................................................................................................................................................12

6–10. Maps showing—

6. Water levels in monitoring wells and potentiometric surface of the shallow part 

of the glacial drift aquifer in the vicinity of the Nelson Landfill site, July 13, 2005.............15

7. Value of selected field parameters in samples from monitoring wells in the vicinity 

of the Nelson Landfill site, July 27, 2005....................................................................................20

8. Concentration of major ions in samples from monitoring wells in the vicinity of the 

Nelson Landfill site, July 27, 2005...............................................................................................22

9. Concentration of nitrogen compounds in samples from monitoring wells in the 

vicinity of the Nelson Landfill site, July 27, 2005......................................................................24

10. Concentration of selected metals in samples from monitoring wells in the vicinity 

of the Nelson Landfill site, July 27, 2005....................................................................................30
iv

Tables

1. Monitoring well data in the vicinity of the Nelson Landfill site, Yorkville, Illinois ...................6

2. Lithologic logs for the vertical aquifer profile (VAP) locations in the vicinity of 

the Nelson Landfill site ...................................................................................................................13

3. Vertical aquifer profile data in the vicinity of the Nelson Landfill site, April 4-27, 2005.......16

4. Field parameters measured in water from monitoring wells and seeps in the 

vicinity of the Nelson Landfill site.................................................................................................18

5. Correlation of selected constituents in ground water from monitoring wells in the 

vicinity of the Nelson Landfill site, July 27, 2005.........................................................................19

6. Concentration of major ions and nitrogen compounds in water from monitoring 

wells and seeps in the vicinity of the Nelson Landfill site........................................................21

7. Concentration of volatile organic compounds in water from monitoring wells and 

seeps in the vicinity of the Nelson Landfill site ..........................................................................25

8. Concentration of pesticide compounds in water from monitoring wells and seeps 

in the vicinity of the Nelson Landfill site......................................................................................27

9. Concentration of metals and cyanide in water from monitoring wells and seeps in 

the vicinity of the Nelson Landfill site ..........................................................................................28
Conversion Factors, Datums, and Water-Quality Units

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) .3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre .4047 hectare (ha)

square foot (ft2) .09290 square meter (m2)

section (640 acres or 1 square mile) 259.0 square hectometer (hm2) 

Volume

gallon (gal) 3.785 liter (L) 

Flow rate

foot per day (ft/d) .3048 meter per day (m/d)

gallon per minute (gal/min) 3.785 liter per minute

gallon per day (gal/d) 3.785 liter per day

cubic foot per day (ft3/d) .02832 cubic meter per day (m3/d)

Pressure

pound per square inch (lb/in2) 6.895 kilopascal (kPa) 

Hydraulic conductivity

foot per day (ft/d) .3048 meter per day (m/d)

Hydraulic gradient

foot per foot (ft/ft) .3048 meter per meter (m/m)

Transmissivity*

foot squared per day (ft2/d) .09290 meter squared per day (m2/d) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

 °F=(1.8×°C)+32

Vertical coordinate information for the site is referenced to an internal datum, which is a point 91.48 feet 

below the top of the inner casing in well NL3. 

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of 

aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot squared per day (ft2/d), 

is used for convenience.

Specific conductance is given in microSiemens per centimeter at 25 degrees Celsius (μS/cm at 25 °C).

Oxidation-reduction potential is given in millivolts (mv).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or 

micrograms per liter (μg/L).
By Robert T. Kay

Abstract

The geologic and hydrologic characteristics of the 

sand-and-gravel deposits that compose the glacial drift 

aquifer in the vicinity of the Nelson Landfill site in Yorkville, Illinois indicate that the aquifer could be developed as a source of public water supply. The geology of 

these deposits within the Newark Bedrock Valley is complex, however, and a detailed investigation of their water 

bearing and transmitting properties will be required to 

successfully locate high-capacity wells. 

Volatile organic compounds, pesticides, and cyanide 

were not detected in ground water during this investigation. Metals and nitrogen compounds were not detected 

at concentrations above their Maximum Contaminant 

Level. Iron, manganese, and aluminum were detected at 

concentrations above their Secondary Maximum Contaminant Level and various constituents were detected 

at concentrations above background levels downgradient of the landfill. Nitrate and ammonia, presumably 

derived from agricultural practices, also were detected in 

samples from locations hydraulically upgradient of the 

landfill.

Oxidation-reduction conditions in the aquifer 

become more reducing with depth. This change is 

reflected by a change in the type of nitrogen compound 

detected and the concentration of dissolved oxygen and 

iron in the glacial drift aquifer. Concentrations of some 

of the major ions and metals may be affected by dissolution of carbonate minerals in the aquifer and perhaps 

road salts.

INTRODUCTION

The United City of Yorkville (Yorkville), as well as 

the remainder of Kendall County, in northeastern Illinois is experiencing a large increase in population. This 

increase in population is expected to continue (John Kos, 

Illinois Department of Transportation, written commun., 2004), with a consequent increase in demands for 

water. Water needs for Yorkville, and many of the other 

municipalities in Kendall County, are being supplied 

predominately or exclusively by ground water from the 

Cambrian-Ordovician aquifer system, a series of deep 

bedrock aquifers. Withdrawals from the CambrianOrdovician aquifer system in northeastern Illinois have 

exceeded recharge, resulting in water-level declines of 

hundreds of feet (Burch, 2002) and a degradation in 

water quality (Balding, 1991). These problems, as well 

as concentrations of naturally occurring radium in water 

from the Cambrian-Ordovician aquifer system greater 

than U.S. Environmental Protection Agency (USEPA) 

health-based standards, have resulted in a shift to alternate water supplies, particularly Lake Michigan and the 

various glacial drift aquifers, in parts of northeastern 

Illinois. Yorkville and other municipalities in Kendall 

County anticipate expanding the development of water 

supplies from the glacial drift aquifers in the County to 

meet the growing demand for water.

Sand-and-gravel deposits within the ancestral 

Newark Bedrock Valley in the northern part of Yorkville 

(and elsewhere in Kendall County) (fig. 1) have been 

identified as having a great potential for development of 

municipal-water supplies. Development of water supplies from the Newark Bedrock Valley is hindered by a 

lack of detailed information on the hydrogeology of the 

sand-and-gravel deposits within the valley that compose 

the aquifer. The impact of potential point sources (such 

as the Nelson Landfill)1 (fig. 1) and non-point sources 

(such as fertilizer application and road salts) of contamination on water quality also are concerns for the 

development of drinking-water supplies from the aquifer 

(Kay and others, 2005). In addition, both Yorkville and 

the USEPA are considering redevelopment of the Nelson 

Landfill for reuse as a Brownfield (Anton Graff, United 

City of Yorkville, oral commun., 2004). To supplement 

the information needed to address these concerns and 

issues, the U.S. Geological Survey (USGS), in cooperation with United City of Yorkville and the USEPA 

conducted an investigation of the geology, hydrology, 

and water quality of the glacial drift aquifer in the NewGeology, Hydrology, and Water Quality of the Glacial 

Drift Aquifer in the Vicinity of the Nelson Landfill near 

Yorkville, Illinois

1

So named by U.S. Environmental Protection Agency (Ecology and Environment, Inc., 1986)
Figure 1. Thickness of glacial drift deposits and location of the Nelson Landfill site and the Newark Bedrock Valley in Kendall County, 

Illinois.

   Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
ark Bedrock Valley in the vicinity of the Nelson Landfill 

from February through July 2005.

The Nelson Landfill, hereafter referred to as the site, 

is a closed landfill located on East Beecher road (fig. 2), 

3 mi north of the center of Yorkville. The site is located 

in section 8 of Township 37 north and Range 7 east. 

Approximately 20 acres of the site have been used as a 

landfill (fig. 3). Surface-water drainage at the site is to a 

tributary of Rob Roy Creek (hereafter referred to as the 

creek) (fig. 2), located approximately 500 ft east of the 

site, then south approximately 6 river miles to the Fox 

River. Currently (2006), land use surrounding the site is 

agricultural, but residences are located within 1,600 ft to 

the north and south. The agricultural areas surrounding 

the site are projected to be converted to residential land 

use within the next 10 years (Anton Graff, United City of 

Yorkville, oral commun., 2004). For the purposes of this 

report, the site consists of the area as defined in figure 3; 

the landfill is the area defined by the limits of the waste 

material; and the study area is defined by well NL1 to 

the north, the creek to the east, wells NL4 and GS4D to 

the south, and well NL2 to the west.

Purpose and Scope

This report describes the results of an investigation 

of the hydrogeology and water quality in the glacial drift 

aquifer in the study area surrounding the Nelson Landfill site. The results of water-level measurements, slug 

testing, and water-quality sampling from vertical aquifer profile locations and finished monitoring wells are 

presented. Additionally, the report describes the geology 

and hydrology of the glacial drift aquifer underlying 

the study area, identifies the directions and estimates 

the rate and volume of ground-water flow, describes 

ground-water quality upgradient and downgradient of 

the landfill, and identifies potential factors that affect the 

hydrology and water quality in the glacial drift deposits 

underlying the study area.

Site History

Sand and gravel were mined at the site prior to the 

beginning of landfill operations in 1967. The depth of 

excavation is unknown as is the volume of waste material in the landfill. Landfilled materials consist mostly 

of general refuse and construction debris. An Illinois 

Environmental Protection Agency (IEPA) inspection on 

March 17, 1971 indicated that approximately 8,000 gal 

of septic tank sludge, 500 gal of sludge from a packing 

plant, 500-750 gal of waste from an oil company, 500-

1,000 gal of industrial waste consisting mainly of water 

and ink, and 1,000 gal of plating wastes were disposed 

of in the landfill every week (Ecology and Environment, 

Inc., 1987). Other wastes also were accepted, potentially 

including paint filter wastes, iron/steel foundry wastes, 

plating/polishing wastes, and laboratory/hospital wastes. 

Early reports by State inspectors note the disposal of oily 

wastes and sludge. The site was no longer authorized to 

accept septic or industrial waste in the early 1970s and 

was closed and covered in 1977 (Ecology and Environment, Inc., 1987).

In 1974, at IEPA request, synthetic liners and 

leachate collection systems were installed in disposal 

trenches, but it is unknown if the landfill area is completely lined. No complete leachate collection system is 

believed to be present. Polyethylene pipes were noted to 

have been installed in the trenches for leachate collection 

in January 1975, but the IEPA inspector concluded the 

pipes likely were being crushed by the weight of the fill 

and the liner was ineffective because of improper sealing 

and overlap (Illinois Environmental Protection Agency, 

written commun., 1975).

A sample of ponded leachate was collected at the 

landfill by the IEPA in May 1981 (Illinois Environmental Protection Agency, 1983). The sample contained 

34 mg/L of ammonia, 1.6 mg/L of boron, 2,350 mg/L 

of chemical oxygen demand, 38 mg/L of oil and grease, 

1.14 mg/L of phenolic compounds, 1,800 μg/L of toluene, and unidentified ketones and aliphatic alcohols at 

concentrations up to 7 mg/L. These results indicate that 

constituents in landfill leachate could present a threat to 

human health and the environment if released to ground 

water.

Seven monitoring wells (denoted by an NL prefix 

on figure 3 and table 1) were installed in the glacial drift 

deposits around the site as part of a series of environmental investigations begun in January 1985 (Ecology 

and Environment, Inc., 1986, 1987, 1988, 1991). These 

monitoring wells, and five residential-supply wells, were 

sampled by Ecology and Environment, Inc., in January 

1985. Well-construction logs and interviews with homeowners indicate that the residential-supply wells north 

of the landfill draw water from glacial drift deposits, 

but that most or all of the residential-supply wells south 

of the landfill draw water from the underlying bedrock 

deposits.

Samples collected from monitoring well NL4 during 

January 1985 contained about 16 μg/L of 1,1-dichlorethene (Ecology and Environment, Inc., 1986). The pesticide aldrin was detected in a sample from monitoring 

well NL6A at a concentration of 0.2 μg/L. Vinyl chloride was detected in samples from monitoring wells NL6 

and NL6A at concentrations of 2.1 and 3.0 μg/L, respectively. Concentrations of vinyl chloride exceeded the 

current USEPA Maximum Contaminant Level (MCL) 

for drinking water, which is 2 μg/L (U.S. Environmental Protection Agency, 2004). Calcium, magnesium, 

iron, barium, and manganese were detected in samples 

from monitoring and residential-supply wells located 

hydraulically downgradient of the landfill at concentraIntroduction 
Figure 2. Location of the Nelson Landfill site, Yorkville, Illinois.

 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Introduction 

Figure . Ground-water sampling locations and line of geologic section in the vicinity of the Nelson Landfill site.
tions higher than were detected in samples from 

monitoring wells located hydraulically upgradient 

of the landfill, but at concentrations below MCLs. 

Water levels measured in January 1985 indicated 

that ground-water flow was from north to south with 

a slight easterly component of flow.

Analysis of additional samples collected in 

August 1987 from five of the monitoring wells and 

five residential-supply wells identified the presence 

of 31 μg/L of chloroethane at well NL3, 3 μg/L 

of 1,1-dichloroethane at wells NL3 and NL4, and 

2 μg/L of 1,2-dichloroethene at well NL4 (Ecology and Environment, Inc., 1991). Mercury was 

detected in the sample from well NL3 at a concentration of 4.1 μg/L, which is above its MCL of 2 

μg/L. Arsenic was detected in the sample from well 

NL6 at a concentration of 2.8 μg/L μg/L. Cyanide 

was detected in the samples from wells NL4, NL5, 

and NL6 at concentrations of 22, 27, and 44 μg/L, 

respectively. Semivolatile organic compounds, 

pesticides, and polychlorinated biphenols (PCBs) 

detected at low concentrations (below MCLs) in 

some of the samples were attributed to field and 

laboratory contamination, not in-situ water quality. 

No constituent whose presence was attributed to the 

site was detected in a sample from any residentialsupply well. Water levels measured at the time of 

sampling in 1987 also indicated ground-water flow 

in the study area was from north to south with a 

slight easterly component of flow.

Because of the low concentrations of chemicals in ground water at the monitoring wells and 

the absence of contaminants in samples from the 

nearby residential wells, the site was not investigated further. However, the detection of contaminants, in some instances at concentrations at or 

above MCLs, in addition to the desire by the United 

City of Yorkville to redevelop the site and to use the 

aquifer in the Newark Valley for public-water supply 

have resulted in a renewed interest in investigating 

hydrogeologic and water-quality conditions at and 

near the site. 

STUDY METHODS

The investigation was conducted in three 

phases. Phase one consisted of redevelopment, 

water-level measurement, slug testing, and waterquality sampling of the accessible previously 

installed monitoring wells and water-quality sampling of a surface seep. These data were analyzed to 

guide the placement of additional monitoring wells 

at the site. Phase two consisted of vertical aquifer 

Well name 

profiling for geology, hydraulic properties, and 

(locations 

shown in 

figure 3)

Elevation of 

measuring 

point (feet 

above site 

datum)

Elevation of 

land surface 

(feet above 

site datum)

Well depth 

(feet below 

land surface) Water-level elevation (feet above site datum)

Horizontal 

hydraulic conductivity (feet 

per day) Condition of well

Height of water 

column in well 

on 7/13/2005

(feet) 2/28/2005 7/13/2005 7/27/2005 7/29/2005 8/15/2005

NL1 92.15 91 29 77.32 76.53 76.30 nm nm nm Partial obstruction 14.3

NL2 98.31 96 35 76.70 76.07 75.86 nm nm nm Bent casing 14.9NL3 91.48 89.4 29 74.55 73.87 73.68 73.68 73.48 0.34 In use 13.3

NL4 88.33 87.4 28 74.52 73.77 73.60 nm 73.38 65 In use 14.2NL5 85.07 83 30 nm nm nm nm nm nm Destroyed nmNL6 nm nm 28 nm nm nm nm nm nm Destroyed nm

NL6A nm nm 13 nm nm nm nm nm nm Destroyed nm

GS1S 108.82 106.0 34 nm 77.78 77.59 77.59 77.41 28 In use 5.6GS1D 107.22 106.0 70 nm 74.55 74.36 74.36 74.17 160 In use 38.4GS2S 81.81 79.9 32 nm 73.68 73.51 nm 73.21 640 In use 25.6GS3D 90.70 88.6 75 nm 73.81 73.65 73.62 73.50 110 In use 60.1GS4D 89.23 86.8 75 nm 73.80 73.57 nm 73.38 150 In use 61.8

Table 1. Monitoring well data in the vicinity of the Nelson Landfill site, Yorkville, Illinois.[Datum is 91.48 feet below top of inner casing in well NL3; bold denotes approximate value; nm, not measured]

   Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
water quality at four locations in the study area. Phase 

three consisted of installation, development, water-level 

measurement, slug testing, and water-quality sampling of 

newly installed monitoring wells and a second round of 

water-quality sampling at the previously installed monitoring wells. All field activities, including lithologic 

and water-quality sampling, slug testing, well construction, well development, and equipment decontamination 

were performed in accordance with a USEPA-approved 

Work Plan, a Quality-Assurance Project Plan (QAPP), 

and a Field Sampling Plan, which were developed by the 

USGS for this investigation.

Previously installed monitoring wells NL5, NL6, 

and NL6A had been destroyed prior to the initiation of 

this investigation (table 1) and could not be used. The 

casing in wells NL1 and NL2 was bent, which limited 

the size of the devices (pumps, pressure transducers, 

water-level measurement tapes) that could be inserted 

in the wells. Only water levels could be collected from 

these wells.

Vertical aquifer profiling (VAP) was performed at 

four locations in the vicinity of the landfill (fig. 3) to 

characterize the hydrogeology and water quality with 

depth and to provide screening-level information that 

could be used to guide depth placement of the new monitoring wells. The locations of VAP1 and VAP2 were 

selected to characterize hydrogeology and water quality 

downgradient of the landfill in areas where historical 

sampling from wells open to the shallow part of the glacial drift aquifer (NL3 and NL4) indicated the presence 

of contamination. The location of VAP3 was chosen to 

characterize the aquifer near the creek. The location of 

VAP4 was chosen because it is hydraulically upgradient 

of the landfill, enabling characterization of ambient (that 

part of the aquifer not affected by landfill leachate) water 

quality in the aquifer. VAP consisted of lithologic sampling, water-quality sampling, water-level measurements, 

and slug testing at discrete depths along each boring. 

The first step in the VAP was to obtain a geologic profile 

by collecting lithologic samples. Lithologic samples 

were collected over an interval of 3 to 5 ft approximately 

every 10 ft (for example, at 5-10 ft and 15-20 ft) to a 

depth of 100 ft or sampler refusal, whichever came first. 

Lithologic samples were collected by use of a Geoprobe 

Systems Macrocore sampler with a length of 4 ft and 

a diameter of 1.5 in. The next step in the VAP was the 

collection of water-quality samples from four different 

depths at a second VAP location approximately 10 ft 

from the location of the lithologic profile. Water-level 

measurements and slug tests were performed in each 

of the VAP intervals where water-quality samples were 

collected (table 1). The depth intervals were selected to 

sample four approximately equally spaced intervals of 

the sand-and-gravel deposits identified by the lithologic 

profiling at each VAP location. Water-quality samples, 

water levels, and slug tests were collected by use of a 

temporary well screen with a length of 4 ft and a diameter of 1 in.

The five monitoring wells constructed for this 

investigation (GS1S, GS1D, GS2S, GS3D, and GS4D; 

fig. 3), hereafter referred to as the new monitoring wells, 

were installed July 7 and 8, 2005. The new monitoring wells were drilled using a 8.25 in. outside-diameter 

hollow-stem auger to the depth of the screened interval. 

The wells were installed at the VAP locations and are 

constructed of a flush-threaded, 2-in. diameter schedule 

40 polyvinyl chloride (PVC) screen and riser pipe to be 

consistent with construction materials used for the previously installed monitoring wells. Screens were slotted, 

with a 0.010 in. opening and a length of 5 ft. The depth 

of the screens was selected based on the results of the 

water-quality and hydraulic data collected from the VAP 

at that location. A granular sand pack was placed in the 

annular space from the bottom of the auger typically 

to about 1.5 ft above the top of the screen. About 1 ft 

of filter sand was placed above the granular sand pack. 

About 2 ft of bentonite pellets were placed above the 

filter sand. Bentonite grout was used to fill the borehole 

annulus to about 1.5 ft below ground surface, where an 

above-grade protective well casing encased in concrete 

was installed. Waterproof locking caps were used to seal 

the top of the casing at each well.

Monitoring wells were developed using a combination of bailers, a 1.7 in. diameter hand pump, and a 

high-capacity submersible sampling pump. A minimum 

of five well volumes of water were removed during redevelopment of wells NL3 and NL4. A minimum of 25 

well volumes were pumped during development of the 

new wells to remove water affected by drilling and well 

construction from the aquifer. The newly constructed 

wells were developed at least 5 days after construction 

and at least 13 days prior to sampling. Wells NL3 and 

NL4 were redeveloped 15 days prior to the first sampling 

event of this investigation.

Water levels were measured in the available previously installed monitoring wells on February 28, 2005, 

and in the new and previously installed monitoring 

wells on July 13, 27, 29, and August 15, 2005. Because 

water levels measured on all dates were similar to those 

measured on July 13, only the data from July 13 are discussed. Water levels were measured in each of the VAP 

test intervals at the time of sampling. All ground-water 

levels were measured by use of an electric water-level 

indicator graduated at 0.01 ft and were measured from 

the top of the riser pipe in each of the wells and VAP 

locations.

The elevation of the land surface and the top of 

the riser pipe at each well and VAP location was measured by USGS personnel using a standard, closed loop, 

rod-and-level technique. The latitude and longitude of 

each well was measured by USGS personnel by use of 

a hand-held global positioning device. All elevations 

Study Methods   
are presented relative to an internal datum for the site. 

Ecology and Environment, Inc. (1986) used an internal 

datum for the site when they surveyed the elevation of 

various points on the previously installed wells. The 

identity of this datum was not specified. However, the 

elevation of the top of the inner casing of all of the previously installed wells was recorded. This elevation was 

measured to be 91.48 ft at well NL3. Because the top 

of the inner casing of well NL3 was used as the point of 

reference for the USGS surveying, the internal datum for 

this investigation is a horizontal plane located 91.48 ft 

below the top of the inner casing of well NL3. 

The stage of the creek was measured on July 13, 

2005 near well GS2S (fig. 3). The stage was measured 

by surveying the elevation of the water surface using the 

rod-and-level technique.

Horizontal hydraulic conductivity (Kh) of the deposits was calculated from data collected by USGS personnel during slug tests in previously installed monitoring 

wells NL3 and NL4, in all but one of the VAP test intervals, and in all of the new monitoring wells. Slug tests 

in the monitoring wells involved instantaneous lowering 

of the water level in the well by removal of a solid PVC 

cylinder from the water column and measurement of 

water-level rise (recovery) with time. Slug tests in the 

VAP locations involved use of compressed nitrogen gas 

to lower the water level then measurement of water-level 

rise with time when the pressure was instantaneously 

released. Recovery was measured in both monitoring 

wells and VAP locations by use of a calibrated 0-10 lb/

in2 pressure transducer connected to a datalogger. Waterlevel measurements collected from the monitoring wells 

were collected on a logarithmic time scale, whereas 

water-level measurements collected from the VAP locations were collected on a linear scale of 1 second or less. 

A minimum of two slug tests were done on each well 

and a minimum of three slug tests were done at each 

VAP test interval. Water levels were measured prior to 

the start of each test to ensure that levels had stabilized.

Data from many of the slug tests displayed a continuous decline in water levels through time and were analyzed using the technique of Bouwer and Rice (1976). 

This technique was developed for use in unconfined 

aquifers with wells that fully or partially penetrate an 

aquifer. Water levels from some of the slug tests exhibited an oscillatory response, which was analyzed using 

the van der Kamp (1976) technique. This technique was 

developed for analysis of slug-test data from highly permeable aquifers in which the effects of inertia of water in 

the well dominate the aquifer response (underdampened 

case). A fully penetrating well in a confined aquifer is 

assumed for this technique. The aquifer storage coefficient was assumed to be 0.001 when aquifer transmissivity was calculated. This storage coefficient is probably 

representative of confined conditions where the water 

level is above the well screen. The thickness of the aquifer was assumed to be equal to the saturated length of the 

well screen when Kh was calculated from the transmissivity values.

The van der Kamp and Bouwer and Rice techniques 

further assume the following conditions:

1. Drawdown of the water table in the vicinity of 

the well or VAP location is negligible,

2. Flow above the water table can be ignored,

3. Head losses as the water enters the well are negligible, and 

4. The hydraulic unit tested is homogenous and 

isotropic.

These conditions appear to have been met or approximated in the locations tested during this study.

The following assumptions were made to analyze 

slug-test data:

1. The radius of the casing is equal to the radius of 

the inner casing of the monitoring wells (1 in.) 

or the riser pipe of the VAP locations (0.625 in.).

2. The length of the well through which water 

enters the aquifer is equal to the length of the 

well screen.

3. The borehole radius is equal to one-half the 

nominal outside diameter of the auger used to 

drill the well (8.25 in.) or one-half of the outside 

diameter of the VAP casing (1.125 in.).

Water samples were collected from the monitoring 

wells using standard low-flow techniques in accordance 

with the USEPA approved Field Sampling Plan for the 

investigation. Monitoring wells NL3 and NL4 were 

sampled on March 3, 2005. Monitoring wells GS1S, 

GS1D, GS2S, NL3, GS3D, NL4, and GS4D were sampled on July 27, 2005. A submersible sampling pump 

was used to purge and collect samples from the monitoring wells. Field parameters (temperature, pH, dissolvedoxygen concentration (DO), oxidation-reduction potential (ORP), and specific conductance) of the water were 

measured during purging by use of a calibrated Hydrolab 

Surveyor Datasonde 4 with an in-line flow-through cell 

attachment. Samples for field measurement of turbidity 

were collected at the end of purging and measured by 

use of a calibrated Hach Model 2100P portable turbidity 

meter. Samples for laboratory analysis were collected 

after a minimum of three well volumes had been purged 

and monitoring had established that the field parameters 

were changing by less than 10 percent for every half of a 

well volume.

On March 3, 2005, a water sample was collected 

from a surface seep near former wells NL6 and NL6A 

(fig. 3). A hole was dug about 20 in. deep at the seep 

and filled with about 8 in. of water in about 10 minutes 

after digging. The sample was then collected by partly 

submerging the bottles in the water. Field parameters 

were analyzed by submerging the probes in the water. 

The seep was not present during the July sampling event.

   Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Samples from the VAP locations also were collected using standard low-flow techniques in accordance 

with the USEPA-approved Field Sampling Plan for the 

investigation. Water samples collected from the VAP 

locations were collected after purging 3-8 well volumes 

with a bladder pump. Temperature, pH, DO, ORP, and 

specific conductance of the water typically were measured during purging by use of a calibrated in-line flowthrough cell. pH was not measured at VAP1, and pH, 

ORP, and DO was not measured in the deepest interval 

of VAP2 because the probes were broken. Water samples were collected from VAP locations after monitoring 

established that the field parameters were changing by 

less than 10 percent for every gallon of water purged and 

after at least three well volumes were purged. Chloride and total alkalinity concentrations of the samples 

at VAP2, VAP3, and VAP4 were measured in the field 

immediately prior to sampling by use of colorimetric 

titration techniques. Measurement of chloride and total 

alkalinity analyses from VAP locations was not planned 

originally. These analyses were added when the field 

kits containing the titration equipment became available, 

which was after VAP1 had been sampled. The chloride 

and total alkalinity analyses made with the field kits 

provide “field level” data. The concentration of chloride 

and total alkalinity determined from these samples is not 

considered to be highly accurate. 

Water samples from the monitoring wells, the 

seep, and the VAP locations submitted for laboratory 

analysis were placed in pre-preserved bottles, immediately stored on ice in a cooler, and delivered to the 

laboratory typically within 72 hours of collection. The 

samples were not filtered. Samples collected from the 

VAP locations were analyzed by the laboratory only for 

volatile organic compounds (VOCs). Samples collected 

from the monitoring wells and the seep were analyzed 

for VOCs, metals, major cations, cyanide, pesticide 

compounds, sulfate, ammonia as nitrogen (ammonia), 

nitrate as nitrogen (nitrate), chloride, and alkalinity as 

calcium carbonate (alkalinity). All laboratory samples 

were analyzed by National Environmental Laboratory 

Accreditation Program (NELAP) certified laboratories 

that are approved for use by the IEPA. Samples were 

analyzed using USEPA standard methods according to 

the approved QAPP for the project. Rinsate blank, trip 

blank, matrix spike-matrix spike duplicate (MS/MSD), 

and duplicate samples were collected for quality assurance and quality control (QAQC) during the sampling 

efforts at the monitoring wells as specified in the QAPP. 

Proper chain-of-custody was maintained for all samples. 

Review of the QAQC data indicates the sampling results 

can be used without qualification. Because VAP data 

were used for screening purposes only, blank, MS/MSD, 

and duplicate samples were not collected at the VAP 

locations. 

Concentrations of each constituent, including field 

parameters, detected in water samples from six or more 

monitoring wells during the July 2005 sampling event 

were plotted against each other, and the square of the 

Pearson product-moment correlation coefficient (r2) 

for each plot was calculated by use of Microsoft Excel 

spreadsheet package. Two sets of plots were generated, one including and one excluding the data from 

wells NL4 and GS4D. Data from wells NL4 and GS4D 

were excluded because these wells are located directly 

hydraulically downgradient from the landfill and correlations excluding these wells are more likely to identify 

chemical processes occurring in the ambient aquifer. A 

high degree of correlation was considered to be present 

if the r2 value for the plot exceeded 0.70 (Angel Martin, 

U.S. Geological Survey, oral commun., 2005).

Additional information on data collection and sampling methods is available from the USGS Illinois Water 

Science Center. Copies of the Field Sampling Plan, 

QAPP, and Work Plan also are available from the USGS 

Illinois Water Science Center.

GEOLOGY

The study area is located at the surface contact 

between the Saint Charles Moraine, which is composed 

of the Yorkville Member of the Lemont Formation, and 

outwash plain deposits composed of the Batavia facies of 

the Henry Formation (fig. 4). Regionally, the Yorkville 

Member of the Lemont Formation is composed of clayey 

to silty till with local lenses of silt and sand and gravel 

deposited by glacial ice. The Batavia facies of the Henry 

Formation is composed of sand and gravel deposited 

in streams and rivers derived from glacial meltwater. 

These streams eroded into the bedrock surface during 

the Quaternary System, forming the Newark Bedrock 

Valley (fig. 1). These deposits interfinger throughout the 

Newark Bedrock Valley and are more than 100 ft thick in 

the vicinity of the site (fig. 1). The stratigraphic nomenclature used in this report is that of the Illinois State 

Geological Survey (Willman and others, 1975; Hansel 

and Johnson, 1996) and does not necessarily follow the 

usage of the USGS.

Lithologic logs obtained from previous site-specific investigations (Ecology and Environment, Inc., 

1987) and as part of this study (table 2) indicate that the 

geologic deposits in the study area consist of two general 

types: sand and gravel, and silt and clay till. Although 

general patterns in distribution can be identified, these 

deposits are complexly distributed across the study area. 

Silt-and-clay rich till predominates within the upper 5 to 

30 ft of land surface, with thin sand or sand and gravel 

interspersed (fig. 5). The shallow, predominantly till 

deposit tends to be thickest (about 25 to 30 ft) in the 

Geology   
Figure 4. Surficial geology of Kendall County, Illinois (west of 88o

 30’ modified from Hansel and Johnson, 1996, plate 1, map scale 

1:500,000; east of 88o 30’ and stratigraphic descriptions modified from Willman and Lineback, 1970, map scale 1:250,000, and Hansel and 

Johnson, 1996; mapping of the eastern and western parts of county at different levels of detail and presentation scale accounts for the 

apparent discontinuity in surficial geology). Illinois State Geological Survey stratigraphic nomenclature is used.

10 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Geology 11

Figure 4. Surficial geology of Kendall County, Illinois—continued.
western part of the study area at VAP4 and well NL2; of 

intermediate thickness (about 10 to 20 ft) at NL3/VAP2, 

NL4/VAP1 and NL6; and thinnest (0 to 5 ft) in the center 

of the study area at wells NL1 and NL5 and near the 

creek at VAP3. Sand-and-gravel deposits underlie the 

till and are the predominant lithology from a depth interval of about 16 ft to at least 80 ft at VAP1 and to at least 

100 ft at VAP2 in the south-central part of the study area. 

Sand-and-gravel deposits predominate from about 25 

to 71 ft below land surface at VAP4 in the northwestern 

part of the study area and in much of the interval from 

0 to at least 83 ft at VAP3 near the creek. Till deposits 

were present from about 71 to 100 ft at VAP4 and were 

interspersed throughout the interval from about 49 to 76 

ft at VAP3.

The type and heterogeneity of the geologic deposits 

in the study area are consistent with regional data for the 

Newark Bedrock Valley (Kay and others, 2005) and it is 

likely that the geologic conditions at the site are representative of the Newark Bedrock Valley as a whole. The 

vertical and horizontal heterogeneity of the glacial-drift 

deposits in the study area, an area approximately 2,000 

ft in length and width, indicates that persons seeking to 

develop water supplies from the Newark Bedrock Valley 

will need to perform a detailed geologic exploration to 

locate the most productive water-bearing deposits.

Figure 5. Hydrogeologic section A-A’ in the vicinity of the Nelson Landfill site.

12 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Depth 

(feet below 

land surface) Description

VAP1

5-10 5-6 ft is tan silt and clay till, some gravel, sandy. 6-8 ft is silt and clay till. 8-10 ft is silt, sand, and gravel. Dry. 

15-20 15-16 ft is grey till composed of silt, clay, sand, gravel. 16-20 ft is tan sand and gravel. Saturated.

25-30 Grey sand and gravel. 

36-40 Tan, well sorted, medium-grained sand.

49-53 Sand and gravel. Mostly gravel-sized grains from about 0.3 to 1 cm in size. Some silt and clay.

53-55 Soft zone when drilling. 

57-61 Grey sand and gravel. 

66-70 Predominately grey medium-grained sand. Some gravel up to about 1 cm in size.

78-81 78-80.5 is sand and gravel, grains up to about 3 cm in size. 80.5-81 is grey till.

83 Refusal.

VAP2

7-10 Brown till. Gravel in sand and silt matrix.

17-20 17-17.5 ft is grey silty till. 17.5-19 ft is grey clay, plastic. 19-20 ft is tan coarse sand, about 1 percent gravel. Gravel composed of lithic fragments, subrounded, maximum size about 2 cm.

27-30 Tan coarse-grained sand.

37-40 Very coarse-grained sand. Mostly quartz, some lithic fragments. About 1 percent gravel up to 1 cm in size. 

47-50 Tan, very coarse-grained sand. Mainly quartz, some lithic fragments.

57-60 Sand and gravel. Largest gravel grains larger than size of sampler (2 inches). 

68-71 Grey sand and gravel. Mostly quartz (smaller size) and lithic fragments (larger size). Most grains from 0.1 to 3 cm in size.

79-82 79-81.5 ft is tan medium- to coarse-grained sand. 81.5-82 ft is sand and gravel.

99-102 Very coarse-grained sand and gravel. Composed of lithic fragments.

VAP3

7-10 Grey silty sand and gravel. Gravel is rounded to subrounded lithic fragments. Maximum diameter about 1.5 inches. Moist.

17-20 Grey sand and gravel. Similar to 7-10 ft but little silt.

30-34 Same as 17-20 ft.

40-44 Same as 17-20 ft.

49-52 Tan sandy silt and very fine-grained sand.

57-60 Grey sandy silt.

61-67 Very hard drilling.

67-70 Tan coarse-grained sand and gravel, silty.

70.1-74.9 Very hard drilling.

75-78 75-76 ft is grey till. Cobbles in silt/sand/clay matrix, same as 80-80.5 ft at VAP1. 76-78 ft is grey sand and gravel. Indications of sand and gravel at about 79-82 ft but no sample.

VAP4

8.5-12.5 8.5-11.5 ft is brown till. Gravel in sand and silt matrix. Dry. 11.5-12.5 ft is brown clay till, moist.

19-23 Brown clay and silt till. Wet.

29-33 Tan medium- to coarse-grained sand.

39-43 Tan sandy gravel. Gravel subrounded lithic fragments, mostly dolomite. Average gravel size about 1 cm.

49-53 Grey sand and gravel. Gravel lithic fragments. Maximum size beyond diameter of sampler. Mostly subrounded to rounded.

58-62 Grey sand and gravel. Same as 49-53 ft.

68-72 68-69 ft is grey coarse-grained sand. 69-71 ft is gravel. 71-72 ft is grey clayey, silty till. Gravel fragments up to 1 percent 

of sample. Plastic.

79-82 Brown silt till. Mostly silt, some sand and gravel in silt matrix. Gravel about 1 percent of sample. Often angular. Maximum gravel size about 1 cm. Plastic.

88-91 Same as 79-82 ft.

97-100 Same as 79-82 ft.

Table 2. Lithologic logs for the vertical aquifer profile (VAP) locations in the vicinity of the Nelson Landfill site. 

[ft, feet; cm, centimeter]

Geology 13
HYDROLOGY

The hydraulic unit of concern to this investigation 

is the aquifer composed of the sand-and-gravel deposits 

beneath the study area, hereafter referred to as the glacial 

drift aquifer (fig. 5). The silt and clay till deposits interspersed with the sand-and-gravel deposits are not considered part of the aquifer. The glacial drift aquifer was the 

focus of this investigation because it is a potential source 

for public-water-supply and because it is likely to be 

the primary pathway for contaminant migration associated with the landfill. On a regional basis, and beneath 

much of the study area, the glacial drift aquifer is under 

unconfined conditions. However, the glacial drift aquifer 

is locally confined by fine-grained deposits. 

Water-level elevations measured in the previously 

installed monitoring wells on February 28, 2005, ranged 

from 77.32 ft above the internal site datum at well NL1 

in the northern part of the study area to about 74.5 ft at 

wells NL3 and NL4 in the southern part of the study area 

(table 1). These water-level elevations indicate water in 

the glacial drift aquifer flows from north to south across 

the site. 

Water levels were measured in all available monitoring wells and at the creek on July 13, 2005. Water-level 

elevations in wells open to the shallow part of the glacial 

drift aquifer (wells GS1S, NL1, GS2S, NL3, NL4, NL2) 

ranged from 77.78 ft above the internal site datum at 

well GS1S in the northwestern part of the study area 

to 73.68 ft at well GS2S in the southeastern part of the 

study area near the creek (table 1, fig. 6). Water-level 

elevations on July 13, 2005, are roughly consistent with 

patterns in surface topography (excluding the landfill 

itself) and indicate that water in the glacial drift aquifer 

flows from north to south across the study area, with a 

slight west-to-east component of flow. Comparison of 

water levels at well GS2S with the stage of the creek, 

which was nearly dry on this date, indicates virtually 

horizontal flow between the creek and the glacial drift 

aquifer, and good hydraulic interconnection between 

the aquifer and the creek. This interpretation assumes a 

margin of measurement error of about 0.04 ft. Northern 

Illinois, including the study area, was in a drought during the summer of 2005, and flow conditions defined by 

these measurements may not represent typical conditions.

Water levels measured in monitoring wells open to 

the deeper part of the glacial drift aquifer (wells GS1D, 

GS3D, GS4D) on July 13, 2005, ranged from 74.55 ft 

above the internal site datum at well GS1D in the northwestern part of the study area to about 73.80 ft at wells 

GS3D and GS4D in the southern part of the study area. 

Allowing for differences in the location and number of 

data points, flow direction in the deeper part of the glacial drift aquifer in the study area appears to be similar to 

flow direction in the shallow part. The flow direction is 

predominately from north to south with a slight west-toeast component (fig. 6).

The water-level elevation in the shallow part of the 

glacial drift aquifer was more than 3 ft higher than in the 

deep part of the aquifer at the GS1S/GS1D well cluster, 

indicating the potential for downward flow in this area 

(table 1, fig. 6). The water-level elevation in the shallow 

part of the glacial drift aquifer typically differed by less 

than 0.10 ft from the water level in the deep part of the 

aquifer at the NL3/GS3D and NL4/GS4D well clusters. 

Within the margin of measurement error (about 0.04 

ft), water levels indicate the potential for downward or 

horizontal flow at the NL3/GS3D cluster and horizontal or perhaps slightly upward flow at the NL4/GS4D 

cluster. These water levels generally are consistent with 

the water-level data collected from the VAP intervals. 

Water-level elevation tended to increase in the deeper 

part of the glacial drift aquifer at VAP1 (the location 

of the NL4/GS4D cluster) and tended to decrease with 

depth at VAP2 and VAP4 (the locations of the NL3/

GS3D and GS1S/GS1D clusters, respectively) (table 3). 

Water levels in VAP3 showed a tendency for horizontal 

flow, or to increase slightly with depth, indicating the 

potential for horizontal or perhaps upward flow of water 

from the glacial drift aquifer into the creek. The VAP 

data also is consistent with the water-level data from 

well GS2S and the creek (within the margin of measurement error). These data indicate that vertical flow in the 

glacial drift aquifer is complex. 

If ground water from the glacial drift aquifer flows 

into the creek, it is likely that the creek defines the eastern boundary of any ground-water contamination leaching from the landfill. Furthermore, if contamination is 

present in the ground water in this area, the potential 

exists for that contamination to migrate into sediments 

and water in the creek, where they could impact the environment. Finally, if water flows into the creek, a large 

capacity well drawing water from the glacial drift aquifer 

in this area would have the potential to divert water 

from the creek, reducing the volume of streamflow. A 

reduction in streamflow could adversely affect the creek 

ecosystem.

The north to south direction of ground-water flow 

in the study area is generally consistent with the regional 

flow direction in the glacial drift aquifer (Kay and 

others, 2005). The flow direction in the study area on 

July 13, 2005, also is consistent with the flow direction 

determined from water levels measured in the previously 

installed monitoring wells on February 28, 2005 (table 

1), and from measurements taken by Ecology and Environment, Inc., (1986, 1991) in the mid-1980s. These 

measurements indicate that the flow direction in the glacial drift aquifer beneath the study area has been consistent for at least the past 20 years. It is probable, there14  Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Figure 6. Water levels in monitoring wells and potentiometric surface of the shallow part of the glacial drift aquifer in the vicinity of the 

Nelson Landfill site, July 13, 2005.

Hydrology 15
fore, that the general direction of 

contaminant migration also has not 

changed in that time.

Values for the Kh of the aquifer 

calculated from analysis of slug tests 

done in the VAP test intervals and the 

monitoring wells ranged from 0.27 to 

640 ft/d (tables 1 and 3). The geometric mean Kh of all of the slug-test values 

is 9.2 ft/d. The Kh values displayed no 

obvious patterns with depth, location, 

or lithology (sand, sand-and-gravel, or 

gravel) but indicate that at least parts 

of the glacial drift aquifer are highly 

permeable and may be capable of 

sustaining withdrawals from individual 

wells in excess of 50 gal/min. However, the variation in Kh values, even 

within those parts of the glacial drift 

aquifer consisting of permeable sandand-gravel deposits, indicates that the 

successful installation of high-capacity 

wells and well fields in this aquifer will 

require a detailed geologic exploration and hydrologic evaluation of the 

aquifer.

The horizontal hydraulic gradient 

for the shallow part of the glacial drift 

aquifer was calculated by dividing the 

change in the elevation of the potentiometric surface between two points on 

a line parallel to the direction of flow 

(4 ft, based on data from wells GS1S 

and NL4) by the horizontal distance of 

the flow path between the two points 

(approximately 1,600 ft)(fig. 6). The 

horizontal hydraulic gradient was 

calculated to be about 2.5 X 10-3 ft/ft 

based on the water levels measured on 

July 13, 2005. The low value of this 

gradient is consistent with a permeable 

aquifer. However, this gradient may be 

atypically low because of the effects of 

drought conditions at this time. 

The ground-water velocity (v) in 

an aquifer is defined as 

 v = (Kh/ne)I , (1)

where ne is the effective porosity of the 

aquifer, in percent, and

I is the horizontal hydraulic gradient, in 

ft/ft.

If Kh is assumed to be equal to the 

geometric mean value for the glacial 

drift aquifer (9.2 ft/d), I is equal to the 

Vertical 

aquifer profile 

location 

(shown in 

figure 3)

Depth of test 

interval (feet 

below land 

surface)

Elevation of test 

interval 

(feet above site 

datum)

Elevation of 

water level 

(feet above site datum)

Average 

horizontal 

hydraulic 

conductivity 

(feet per day)

Volatile 

organic 

compound 

detections

Temperature 

(degrees 

Celsius)

pH 

(standard 

units)

Specific 

conductance 

(microSiemens per 

centimeter)

Chloride 

concentration 

from field test 

(milligrams 

per liter)

Alkalinity 

from field test 

(milligrams 

per liter as 

Calcium 

Carbonate)

VAP1 38-42 49-45 74.36 11 nd 11.9 nm 1,320 nm nmVAP1 48-52 39-35 74.51 .27 nd 10.7 nm 1,510 nm nmVAP1 59-63 28-24 74.37 1.6 nd 11.9 nm 1,430 nm nmVAP1 75-79 12-8 76.52 .81 nd 13.0 nm 1,750 nm nmVAP2 37-41 52-48 74.47 .82 nd 13.2 7.6 770 30 280VAP2 57-61 32-28 74.45 18 nd 13.2 7.7 790 40 320VAP2 77-81 12-8 74.44 18 nd 13.0 7.5 830 40 340VAP2 97-101 minus 8 - minus 12 74.40 .53 nd nm nm nm 35 300VAP3 19-24 61-57 74.32 2.6 nd 8.4 7.2 970 50 320VAP3 29-33 51-47 74.30 48 nd 8.4 7.3 1,000 45 540VAP3 39-44 41-36 74.34 .46 nd 8.0 7.1 930 50 270VAP3 79-83 1 - minus 3 74.34 1.7 nd 11.8 7.1 1,130 100 330VAP4 31-35 75-71 77.39 nm nd 11.8 6.8 1,340 90 570VAP4 40-44 66-62 76.71 31 nd 12.0 7.3 1,180 120 370VAP4 50-54 56-52 76.66 34 nd 10.9 7.4 700 25 250VAP4 65-69 41-37 76.69 36 nd 10.4 7.4 730 20 200

Table 3. Vertical aquifer profile data in the vicinity of the Nelson Landfill site, April 4-27, 2005.[Datum is 91.48 feet below top of inner casing in well NL3; nd, not detected; nm, not measured; minus, denotes that value is below datum]

16 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
value determined from the July 13, 2005, data, (2.5 x 

10-3 ft/ft), and ne is assumed to be 30 percent, the average 

ground-water velocity in the glacial drift aquifer is calculated to be about 7.7 X 10-2 ft/d. This velocity is likely 

to be low because of the effects of the drought conditions on the hydraulic gradient. The velocity calculation 

indicates that the ground water underlying the landfill 

area when operations began in 1967 had migrated about 

1,070 ft downgradient by the time this investigation 

occurred in 2005.

Lithologic and water-level data collected as part 

of the current and previous investigations indicate that 

the aquifer is about 100 ft thick in the southern part of 

the landfill. If the landfill has a width of about 1,000 ft 

perpendicular to the direction of ground-water flow, the 

volume of water (Q) flowing through 1 ft2 of the aquifer 

is given by

 Q = KhAI, (2)

where A is the cross-sectional area through which water 

is flowing (1,000 ft by 100 ft), I is the horizontal hydraulic gradient (2.5 X 10-3 ft/ft), and Kh is the mean horizontal hydraulic conductivity (9.2 ft/d). Solving equation 

2 indicates that about 2,300 ft3/d (about 16,900 gal/d) 

of water flows through the aquifer beneath the landfill 

based on the hydraulic conditions present on July 13, 

2005.

WATER QUALITY

Water-quality data collected from the seep and the 

monitoring wells fall into five general categories: field 

parameters, major ions, nitrogen compounds, organic 

compounds, and metals and cyanide. Water-quality 

data collected from the VAP locations consisted of field 

parameters, field measurements of concentration of chloride and alkalinity, and VOCs. 

Water samples also were collected from three 

locations in the creek on June 17, 2005, by Civil and 

Environmental Consultants Inc. as part of a separate 

investigation (fig. 2). Creek samples were analyzed for 

VOCs, nitrogen compounds, cyanide, arsenic, barium, 

cadmium, chromium, lead, mercury, selenium, and silver 

(Gordon Stevens, Civil and Environmental Consultants 

Inc., written commun., 2005). Site SS1 is upstream of 

the creek area receiving ground water that may have 

been chemically affected by the landfill. Site SS2 is near 

well GS2S and in a part of the creek that may be receiving ground water that may have been chemically affected 

by the landfill. Site SS3 is about 900 ft south of the 

landfill, south of the confluence with the main branch of 

Rob Roy Creek, and in a part of the creek that also may 

have been receiving ground water that was chemically 

affected by the landfill.

Field Measurements

Turbidity is a measure of the clarity of water and is 

an indication of the amount of particulate matter in the 

sample. Because the presence of particulate matter in a 

sample container can affect the concentration of numerous dissolved constituents in the water, the most representative water samples should be those with minimal 

turbidity. Sample turbidity was not measured at the VAP 

locations, but the samples were highly turbid based on 

visual observation, and the buildup of particulate matter in the flow-through cell substantially affected the 

measurements of DO and ORP despite efforts to keep 

the probes clean. As a consequence, DO and ORP values from the VAP sampling are not reported. Although 

it was not quantified, the turbidity of the seep sample 

was high based on visual observation, which may have 

affected the sample results. The turbidity of the samples 

collected from the monitoring wells typically was less 

than 10 nephelometric turbidity units (NTUs) (table 4). 

Turbidity values showed a low degree of correlation with 

the value of every other constituent (table 5), indicating 

that the sample results are not substantially affected by 

interactions with particulate matter and can be considered representative of in-situ water quality.

Temperature of the water samples from the monitoring wells and the VAP locations ranged from 8.0 to 14.2 

o

C (tables 3 and 4). The temperature value likely was 

affected by the ambient air temperature during sampling. 

Therefore, temperature readings are not considered representative of in-situ water quality, and spatial or temporal patterns in water temperature were not determined.

Specific conductance is a measure of the capacity 

of a solution to conduct an electrical current and commonly is correlated with the total concentration of dissolved constituents. Specific conductance of the samples 

from the monitoring wells (fig. 7) and the VAP locations ranged from 520 to 1,970 μS/cm (tables 3 and 4). 

Specific conductance of samples from the monitoring 

wells and the VAP showed similar values and patterns. 

Because the data from the VAP locations is more extensive, this discussion focuses on the specific-conductance 

values collected during the VAP. Specific conductance 

values at VAP4, the location most likely to be representative of the ambient aquifer (fig. 3), ranged from 704 

to 1,338 μS/cm and were almost a factor of two higher 

in the shallow part of the aquifer than in the deep part. 

Specific conductance values from VAP1, VAP2, and 

VAP3 (fig. 3) tended to be slightly higher in the deeper 

part of the aquifer at each location, but showed no large, 

easily identified variations with depth. Specific conductance values tended to be lower overall at VAP2 and 

Water Quality 17
higher overall at VAP1 (located directly downgradient 

of the landfill) than in the remaining VAP locations. 

Specific conductance of the seep sample was 715 μS/cm. 

This moderate value is assumed to indicate the presence 

of recent snowmelt mixed with leachate at the seep during sample collection.

pH is the negative log of the concentration of hydrogen ions in the water and can affect the concentration of 

a number of constituents in water from the aquifer. The 

pH of ground-water samples from the monitoring wells 

and the VAP locations ranged from 6.7 to 7.7 (tables 

3 and 4). The pH of the seep sample was 6.8. These 

values are all near the neutral pH of 7.0. 

The oxidation-reduction potential (ORP) of water 

is a measure of electron activity and is an indicator of 

the relative tendency of a solution to accept electrons 

from, or lose electrons to, the surrounding environment 

during chemical reactions. The lower the ORP value, 

the more reducing, or electron accepting, the solution. 

The ORP of a solution affects the valence state of iron, 

nitrogen, sulfur, and other constituents, which in turn can 

affect their form and solubility. The ORP of a solution 

also affects, and is affected by, the type and activity of 

the microbiologic communities in an aquifer, which can 

affect the breakdown of nitrogen compounds and some 

types of VOCs. ORP values in samples from the monitoring wells ranged from -102 to 80 mv (fig. 7, table 

4). ORP values decrease with depth at each monitoring 

well cluster, indicating that the aquifer becomes more 

reducing with depth below the water table. The positive values for ORP detected in wells NL3 and GS1S, 

which are open to the upper 15 ft of the aquifer (table 

1), coupled with the negative ORP value at well GS2S, 

which is open to the shallow part of the aquifer but is 

screened about 25 ft below the top of the aquifer (table 

1), indicates that the transition between the more oxidizing and more reducing conditions may occur in an interval within the upper 15-25 ft of the aquifer. Comparison 

of ORP values at wells NL3 and NL4 from March and 

July 2005 indicates that values were lower in July, especially at well NL4. This decrease in ORP may reflect 

the effects of reduced recharge of oxygenated precipitation during the drought on geochemical conditions in the 

shallow part of the aquifer. The ORP of the seep sample 

was 86 mv.

Concentrations of dissolved oxygen (DO) are an 

indication of ORP conditions in an aquifer. DO concentrations of about 0.5 mg/L or less typically are 

considered representative of anoxic (oxygen deficient) 

waters. The removal of DO from the aquifer can be a 

precursor to the development of more reducing geochemical conditions, which can have both beneficial and 

detrimental effects on water quality. The DO concentration in the water from the monitoring wells ranged from 

0.09 to 3.53 mg/L (table 4, fig. 7). DO concentrations 

greater than 2 mg/L in wells NL3 and GS1S indicate 

the presence of moderate amounts of dissolved oxygen 

in the shallow (upper 15 ft) (table 1) part of the ambient 

aquifer. DO values less than 0.5 mg/L in the water from 

shallow well NL4 may reflect the effects of the landfill 

on water chemistry. DO values decreased with depth 

in the aquifer, particularly at NL3/GS3D and GS1S/D 

clusters, where substantial concentrations of DO were 

present in the shallow ground water. This pattern is 

consistent with the patterns in ORP. DO and ORP 

showed a high degree of positive correlation (r2 greater 

than 0.80) (table 5) both with and without the data from 

wells NL4 and GS4D. This result is further indication 

Sample location 

(shown in 

figure 3)

Temperature

(degrees Celsius)

Dissolved oxygen 

concentration 

(milligrams 

per liter)

Oxidationreduction 

potential 

(millivolts)

pH 

(standard units)

Specific

conductance

(microSiemens 

per centimeter)

Turbidity

(nephelometric 

turbidity units)

March 3, 2005

NL3 9.2 2.24 80 7.0 530 5.6

NL4 10.2 .30 69 6.7 1,190 1.1

Seep 3.3 5.54 86 6.8 715 nm

July 27, 2005

GS1S 12.6 3.53 80 6.8 1,175 5.5

GS1D 12.1 .09 -102 7.4 720 2.4

GS2S 12.2 .14 -71 7.1 1,040 5.7

NL3 14.2 2.79 59 7.2 520 12.3

GS3D 12.4 .13 -18 7.1 890 3.9

NL4 11.1 .16 -20 6.9 1,145 3.1

GS4D 12.9 .10 -72 6.8 1,970 2.1

Table 4. Field parameters measured in water from monitoring wells and seeps in the vicinity of the Nelson Landfill site.

[nm, not measured]

18 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
that conditions are more reducing in 

the deep part of the aquifer. These 

data further indicate that biologic 

and chemical reactions are consum-

ing dissolved oxygen in the shallow 

part of the aquifer, and that this 

process appears to be completed by 

the time water travels to the deeper 

part. Furthermore, DO values less 

than 0.5 mg/L in the water from 

well GS2S, which is screened more 

than 25 ft below the top of the 

aquifer (table 1), may indicate that 

the oxygen-consuming reactions are 

occurring within the upper 15-25 ft 

of the aquifer. The concentration 

of DO in the seep sample was 5.54 

mg/L (table 4), which is indicative 

of the recent snowmelt source and 

perhaps the exchange of oxygen 

from the atmosphere into water in 

the shallow soil. 

Major Ions

For the purposes of this report, 

the major cations are calcium, 

magnesium, sodium, and potassium. 

The major anions are chloride, sul-

fate, and alkalinity as milligrams per 

liter of calcium carbonate (table 6). 

Alkalinity in these samples is likely 

to be primarily due to the presence 

of the bicarbonate ion (HCO

3

-

).

Chloride concentrations in the 

samples from the seep and monitor-

ing wells ranged from 1.9 to 220 

mg/L (table 6) and were similar 

between sampling events at wells 

NL3 and NL4. Chloride concentra-

tions in the samples from the VAP 

locations ranged from 20 to 120 

mg/L (table 3) and show poor to 

good correlation with the data from 

the monitoring wells, where simi-

lar intervals were tested. Chloride 

concentrations increased by at 

least a factor of four with depth 

at the GS1S/D, NL3/GS3D and 

NL4/GS4D well clusters (fig. 8), 

although they showed a less defi-

nite relation at the VAP locations. 

Overall chloride concentrations 

were higher at the NL4/GS4D well 

cluster, particularly well GS4D, 

Constituent

Constituent Barium Iron Manganese Strontium Calcium Magnesium Sodium Potassium Alkalinity Sulfate Chloride

Dissolved 

oxygen

Oxidationreduction 

potential

Specific 

conductance pH

Barium - - - - - - - - - - - - - - -Iron 0.82 - - - - - - - - - - - - - -Manganese .50 0.20 - - - - - - - - - - - - -Strontium .51 .43 0.75 - - - - - - - - - - - -Calcium .43 .11 .48 0.19 - - - - - - - - - - -Magnesium .40 .11 .41 .20 0.97 - - - - - - - - - -Sodium .00 -.09 -.02 -.22 .32 0.33 - - - - - - - - -Potassium .83 .51 .87 .77 .58 .54 0.00 - - - - - - - -Alkalinity .10 .00 .19 .00 .82 .78 .68 0.18 - - - - - - -Sulfate .90 .74 .32 .25 .32 .25 .00 .59 0.07 - - - - - -Chloride .59 .44 .82 .99 .28 .28 -.15 .86 .02 0.32 - - - - -Dissolved oxygen

-.32 -.41 -.42 -.88 -.02 -.04 .43 -.47 .06 -.11 -0.81 - - - -

Oxidationreduction potential

-.33 -.58 -.16 -.63 .00 -.02 .34 -.31 .11 -.13 -.56 0.86 - - -

Specific conductance .25 .04 .21 .04 .92 .92 .59 .31 .91 .19 .08 .00 0.00 - -pH .00 .14 -.02 .04 -.40 -.32 -.71 .00 -.78 .00 .05 -.37 -.53 -0.53 -Turbidity -.10 -.09 -.17 -.35 -.27 -.41 -.01 -.25 -.11 .00 -.35 .36 .40 -.24 -0.01

Table 5. Correlation of selected constituents in ground water from monitoring wells in the vicinity of the Nelson Landfill site, July 27, 2005. (Excludes data from wells NL4 and GS4D. Bold denotes correlation coefficient values greater than 0.70; positive values denote direct correlation, negative values denote inverse correlation)

Water Quality 19
Figure 7. Value of selected field parameters in samples from monitoring wells in the vicinity of the Nelson Landfill site, July 27, 2005.

20 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
than in the rest of the aquifer. Wells NL4 and GS4D are 

located directly downgradient of the landfill.

Alkalinity in the samples from the seep and monitoring wells ranged from 270 to 690 mg/L as CaCO3, 

making it the dominant anion in the aquifer (table 6). 

Alkalinity concentrations at wells NL3 and NL4 were 

similar between sampling events. Alkalinity values in 

the samples from the VAP locations ranged from 200 to 

570 mg/L as CaCO3 (table 3) and show moderate to good 

correlation with the data from the monitoring wells, 

where similar intervals were tested. Alkalinity values 

increased with depth at the NL3/GS3D and NL4/GS4D 

well clusters but decreased with depth at the GS1S/D 

cluster (fig. 8). No easily identified relation between 

alkalinity and depth was present at the VAP locations. 

Alkalinity values tended to be higher at the NL4/GS4D 

well cluster, particularly in well GS4D, than in the rest 

of the aquifer. Wells NL4 and GS4D are located directly 

downgradient of the landfill.

Sulfate concentrations in the samples from the seep 

and monitoring wells ranged from 14 to 190 mg/L (table 

6, fig. 8). Sulfate concentrations were identical between 

sampling events at well NL3 but varied by more than a 

factor of six between sampling events at well NL4. Sulfate concentrations varied by less than a factor of three 

at the GS1S/D, NL3/GS3D and NL4/GS4D well clusters 

and showed no consistent patterns with depth during 

the July 2005 sampling. Sulfate concentrations were 

as much as an order of magnitude higher at well GS2S, 

located near the creek, than in the rest of the aquifer.

Calcium concentrations in the samples from the 

seep and monitoring wells ranged from 69 to 137 mg/L 

(table 6), making it the dominant cation in the aquifer. 

Calcium concentrations were similar between sampling 

events at wells NL3 and NL4. Calcium concentrations varied by less than a factor of two at the GS1S/D, 

NL3/GS3D and NL4/GS4D well clusters and showed no 

consistent patterns in concentration with depth or location during the July 2005 sampling (fig. 8).

Magnesium concentrations in the samples from 

the seep and monitoring wells ranged from about 31 to 

81 mg/L and were similar between sampling events at 

wells NL3 and NL4 (table 6). Magnesium concentrations varied by less than a factor of two at the GS1S/D, 

NL3/GS3D, and NL4/GS4D well clusters and showed no 

consistent patterns in concentration with depth (fig. 8). 

Magnesium concentrations tended to be higher at the 

NL4/GS4D well cluster than in the rest of the aquifer. 

Wells NL4 and GS4D are located directly downgradient of the landfill. Calcium, magnesium, and alkalinity 

concentrations typically show a high degree of positive 

correlation, particularly if the data from wells NL4 and 

GS4D are not included in the analysis (table 5). This 

correlation indicates that these constitutes are derived 

Table 6. Concentration of major ions and nitrogen compounds in water from monitoring wells and seeps in the vicinity of the Nelson 

Landfill site.

[dup, duplicate sample; mg/L, milligrams per liter; na, none available; <, denotes constituent not detected and detection limit; MCL, U.S. Environmental Protection Agency Maximum Contaminant Level; SMCL, U.S. Environmental Protection Agency Secondary Maximum Contaminant Level]

Locations sampled on March 15, 2005

Constituent NL3 NL4 NL4 (dup) Seep MCL SMCL

Calcium (mg/L) 69.1 103 104 96.3 na na

Magnesium (mg/L) 32.4 67.4 68.3 50.8 na na

Alkalinity (mg/L as calcium carbonate) 290 500 490 280 na na

Sulfate (mg/L) 19 99 100 70 na 250

Chloride (mg/L) 1.9 54 55 28 na 250

Ammonia (NH) as nitrogen (mg/L) <.02 3 3.1 .51 na na

Nitrate as nitrogen (mg/L) <.10 <.10 <.10 <.10 10 na

Locations sampled on July 27, 2005

Constituent GS1S GS1D GS2S NL3 GS3D NL4 GS4D MCL SMCL

Calcium (mg/L) 133 90.1 137 69 122 101 110 na na

Magnesium (mg/L) 56.4 43.2 56.3 31.1 51.7 63.6 80.7 na na

Sodium (mg/L) 44.9 5.86 12.3 5.29 8.72 59.1 147 na na

Potasium (mg/L) 1.4 1.49 3.33 .63 2.51 8.48 36 na na

Alkalinity (mg/L as calcium carbonate) 420 280 360 270 360 490 690 na na

Sulfate (mg/L) 34 14 190 19 21 15 34 na 250

Chloride (mg/L) 5.2 22 39 2.1 36 46 220 na 250

Ammonia (NH) as nitrogen (mg/L) <.02 .03 .98 <.02 <.02 3.4 31.7 na na

Nitrate as nitrogen (mg/L) 3.8 <.10 <.10 <.10 <.10 <.10 <.10 10 na

Water Quality 21
Figure 8. Concentration of major ions in samples from monitoring wells in the vicinity of the Nelson Landfill site, July 27, 2005.

22 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
primarily from the dissolution of limestone and dolomite 

minerals in the ambient aquifer.

Sodium concentrations in the samples from the 

monitoring wells ranged from about 5 to 147 mg/L 

during the July 2005 sampling (table 6, fig. 8). Sodium 

concentrations in wells NL4 and GS4D, particularly 

well GS4D, were higher than in the remaining wells, by 

an order of magnitude for some wells. Wells NL4 and 

GS4D are located directly downgradient of the landfill. 

Sodium concentrations varied by less than a factor of 

two at the NL3/GS3D cluster, but showed more variability at the GS1S/D and NL4/GS4D well clusters. Sodium 

concentrations showed no consistent patterns in concentration with depth during the July 2005 sampling. 

Potassium concentrations in the samples collected 

from the monitoring wells in July 2005 ranged from less 

than 1 to 36 mg/L (table 6, fig. 8). Potassium concentrations were similar with depth at the GS1S/D well cluster 

but were substantially higher in the deeper part of the 

aquifer at the NL3/GS3D and NL4/GS4D clusters during 

the July 2005 sampling. Potassium concentrations in 

wells NL4 and GS4D, located downgradient of the landfill, were higher than in the remaining wells, by more 

than an order of magnitude in some wells. Potassium 

concentrations showed a high degree of positive correlation with chloride concentrations (table 5), indicating 

potassium in the ambient aquifer may be partly derived 

from road salts.

Nitrogen Compounds

Nitrogen-containing compounds occur primarily 

as ammonia (NH3) or nitrate (NO3

-

) in natural water. 

The form of the compounds depends on the geochemical environment of the solution, with ammonia being 

the dominant form in more reducing (anoxic) water and 

nitrate predominating in more oxidizing water. Concentrations of nitrogen compounds greater than 5 mg/L 

as nitrogen are often associated with septic wastes (one 

of the wastes disposed of at the landfill) and the use of 

agricultural fertilizer.

Nitrate as nitrogen was detected at a concentration 

of 3.8 mg/L in the sample from shallow upgradient well 

GS1S (table 6, fig. 9), below the USEPA MCL of 10 

mg/L. Nitrogen in the form of ammonia was detected 

at the seep and in the samples from wells GS1D, GS2S, 

NL4, and GS4D at concentrations ranging from 0.51 to 

nearly 32 mg/L. Ammonia concentrations were substantially higher in wells NL4 and GS4D, and particularly 

well GS4D, than in the remaining wells. These wells are 

located directly downgradient of the landfill. There is no 

USEPA or Illinois drinking-water standard for ammonia.

The form of the nitrogen in this aquifer is affected 

by the presence of oxygen and the ORP in the aquifer. 

Nitrate predominates in the oxygenated, higher ORP 

water in the shallow part of the aquifer at well GS1S. 

Ammonia predominates in the anoxic, lower ORP water 

more than about 25 ft below the top of the aquifer at 

wells GS1D, GS2S, GS3D, NL4, and GS4D (table 1), 

indicating that the processes responsible for the conversion of nitrate to ammonia in the ambient part of the 

glacial drift aquifer are occurring in a zone within the 

upper 15-25 ft of the aquifer. Nitrogen compounds were 

not detected in the oxygenated, higher ORP water at 

well NL3. The presence of detectable concentrations of 

nitrogen compounds in shallow upgradient well GS1S 

indicates that the surface application of agricultural 

fertilizers may affect ambient water quality in the glacial 

drift aquifer. However, nitrate as nitrogen was detected 

in only one well and at a concentration less than half its 

MCL.

Ammonia as nitrogen was detected at concentrations 

of about 0.60 mg/L in the creek at all sampling locations 

(Gordon Stevens, Civil and Environmental Consultants 

Inc., written commun., 2005). Nitrate as nitrogen was 

not detected at site SS1 or SS2, but was detected at a 

concentration of 1.34 mg/L at site SS3. Concentrations 

of nitrogen compounds in the creek do not appear to be 

affected by the landfill.

Organic Compounds

Organic compounds (pesticides and VOCs) were not 

detected in samples collected from the seep, monitoring wells, or the VAP locations during this investigation 

(tables 3, 7, 8). VOCs were not detected in any of the 

samples collected from the creek (Gordon Stevens, Civil 

and Environmental Consultants Inc., written commun., 

2005). VOCs were among the primary types of potential 

contaminants of concern at the site and their absence 

from the wells and the VAP sample locations, coupled 

with the apparent stability in flow directions through the 

years, indicates that capping of the landfill and natural 

attenuation processes have reduced the size of the VOC 

plume in the glacial drift aquifer in this area or eliminated it altogether. The absence of detectable concentrations of pesticide compounds in the monitoring wells 

also indicates that the agricultural application of these 

compounds does not appear to have a substantial effect 

on ambient water quality in the glacial drift aquifer in 

this area. However, the pesticide compounds analyzed 

for as part of this investigation are used to control insects 

(insecticides). Pesticide compounds used to control 

plants (herbicides) were not included in these analyses. 

The presence of herbicides or pesticide degradates in the 

glacial drift aquifer has not been determined.

Water Quality 23
Figure 9. Concentration of nitrogen compounds in samples from monitoring wells in the vicinity of the Nelson Landfill site, July 27, 2005.

24  Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Locations sampled on March 15, 2005

Constituent NL3 NL4 NL4 (dup) Seep MCL

Acetone (ug/L) <1 <1 <1 <1 na

Benzene (ug/L) <1 <1 <1 <1 5

Bromodichloromethane (ug/L) <1 <1 <1 <1 na

Bromoform (ug/L) <1 <1 <1 <1 na

Bromomethane (ug/L) <1 <1 <1 <1 na

2-Butanone (ug/L) <1 <1 <1 <1 na

Carbon disulfide (ug/L) <5 <5 <5 <5 na

Carbon tetrachloride (ug/L) <1 <1 <1 <1 5

Chlorobenzene (ug/L) <1 <1 <1 <1 100

Chloroethane (ug/L) <1 <1 <1 <1 na

Chloroform (ug/L) <1 <1 <1 <1 na

Chloromethane (ug/L) <1 <1 <1 <1 na

Dibromochloromethane (ug/L) <1 <1 <1 <1 na

1,1-Dichloroethane (ug/L) <1 <1 <1 <1 na

1,2-Dichloroethane (ug/L) <1 <1 <1 <1 5

1,1-Dichloroethene (ug/L) <1 <1 <1 <1 7

trans-1,2-Dichloroethene (ug/L) <1 <1 <1 <1 100

cis-1,2-Dichloroethene (ug/L) <1 <1 <1 <1 70

1,2-Dichloropropane (ug/L) <1 <1 <1 <1 5

cis-1,3-Dichloropropene (ug/L) <1 <1 <1 <1 na

trans-1,3-Dichloropropene (ug/L) <1 <1 <1 <1 na

Ethylbenzene (ug/L) <1 <1 <1 <1 700

2-Hexanone (ug/L) <10 <10 <10 <10 na

Methylene chloride (ug/L) <5 <5 <5 <5 na

Methyl tert-butyl ether (ug/L) <5 <5 <5 <5 na

4-Methyl-2-pentanone (ug/L) <10 <10 <10 <10 na

Styrene (ug/L) <1 <1 <1 <1 100

1,1,2,2-Tetrachloroethane (ug/L) <1 <1 <1 <1 na

Tetrachloroethene (ug/L) <1 <1 <1 <1 5

Toluene (ug/L) <1 <1 <1 <1 1,000

1,1,1-Trichloroethane (ug/L) <1 <1 <1 <1 200

1,1,2-Trichloroethane (ug/L) <1 <1 <1 <1 5

Trichloroethene (ug/L) <1 <1 <1 <1 5

Vinyl acetate (ug/L) <1 <1 <1 <1 na

Vinyl chloride (ug/L) <1 <1 <1 <1 2

m,p-xylene (ug/L) <2 <2 <2 <2 10,000 for all xylene isomers o-xylene (ug/L) <1 <1 <1 <1

Table 7. Concentration of volatile organic compounds in water from monitoring wells and seeps in the vicinity of the Nelson Landfill site.

[dup, duplicate sample; MCL, U.S. Environmental Protection Agency Maximum Contaminant Level; ug/L, micrograms per liter; <, denotes constituent not 

detected and detection limit; na, not available]

Water Quality 25
Locations sampled on July 27, 2005

Constituent GS1S GS1D GS2S NL3 GS3D NL4 GS4D MCL

Acetone (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Benzene (ug/L) <1 <1 <1 <1 <1 <1 <1 5

Bromodichloromethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Bromoform (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Bromomethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

2-Butanone (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Carbon disulfide (ug/L) <5 <5 <5 <5 <5 <5 <5 na

Carbon tetrachloride (ug/L) <1 <1 <1 <1 <1 <1 <1 5

Chlorobenzene (ug/L) <1 <1 <1 <1 <1 <1 <1 100

Chloroethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Chloroform (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Chloromethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Dibromochloromethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

1,1-Dichloroethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

1,2-Dichloroethane (ug/L) <1 <1 <1 <1 <1 <1 <1 5

1,1-Dichloroethene (ug/L) <1 <1 <1 <1 <1 <1 <1 7

trans-1,2-Dichloroethene (ug/L) <1 <1 <1 <1 <1 <1 <1 100

cis-1,2-Dichloroethene (ug/L) <1 <1 <1 <1 <1 <1 <1 70

1,2-Dichloropropane (ug/L) <1 <1 <1 <1 <1 <1 <1 5

cis-1,3-Dichloropropene (ug/L) <1 <1 <1 <1 <1 <1 <1 na

trans-1,3-Dichloropropene (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Ethylbenzene (ug/L) <1 <1 <1 <1 <1 <1 <1 700

2-Hexanone (ug/L) <10 <10 <10 <10 <10 <10 <10 na

Methylene chloride (ug/L) <5 <5 <5 <5 <5 <5 <5 na

Methyl tert-butyl ether (ug/L) <5 <5 <5 <5 <5 <5 <5 na

4-Methyl-2-pentanone (ug/L) <10 <10 <10 <10 <10 <10 <10 na

Styrene (ug/L) <1 <1 <1 <1 <1 <1 <1 100

1,1,2,2-Tetrachloroethane (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Tetrachloroethene (ug/L) <1 <1 <1 <1 <1 <1 <1 5

Toluene (ug/L) <1 <1 <1 <1 <1 <1 <1 1,000

1,1,1-Trichloroethane (ug/L) <1 <1 <1 <1 <1 <1 <1 200

1,1,2-Trichloroethane (ug/L) <1 <1 <1 <1 <1 <1 <1 5

Trichloroethene (ug/L) <1 <1 <1 <1 <1 <1 <1 5

Vinyl acetate (ug/L) <1 <1 <1 <1 <1 <1 <1 na

Vinyl chloride (ug/L) <1 <1 <1 <1 <1 <1 <1 2

m,p-xylene (ug/L) <2 <2 <2 <2 <2 <2 <2 10,000 for all xylene isomers o-xylene (ug/L) <1 <1 <1 <1 <1 <1 <1

Table 7. Concentration of volatile organic compounds in water from monitoring wells and seeps in the vicinity of the Nelson Landfill 

site—continued.

[dup, duplicate sample; MCL, U.S. Environmental Protection Agency Maximum Contaminant Level; ug/L, micrograms per liter; <, denotes constituent not 

detected and detection limit; na, not available]

26 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Locations sampled on March 15, 2005

Constituent NL3 NL4 NL4 (dup) Seep MCL

Aldrin (ug/L) <0.51 <0.51 <0.51 <0.51 na

alpha-BHC (ug/L) <.51 <.51 <.51 <.51 na

beta-BHC (ug/L) <.51 <.51 <.51 <.51 na

gamma-BHC (lindane) (ug/L) <.51 <.51 <.51 <.51 na

delta-BHC (ug/L) <.51 <.51 <.51 <.51 na

alpha-Chlordane (ug/L) <.51 <.51 <.51 <.51 na

gamma-Chlordane (ug/L) <.51 <.51 <.51 <.51 na

Chlordane (ug/L) <.10 <.10 <.10 <.10 2

4,4’-DDD (ug/L) <.51 <.51 <.51 <.51 na

4,4’-DDE (ug/L) <.51 <.51 <.51 <.51 na

4,4’-DDT (ug/L) <.51 <.51 <.51 <.51 na

Dieldrin (ug/L) <.51 <.51 <.51 <.51 na

Endosulfan I (ug/L) <.51 <.51 <.51 <.51 na

Endosulfan II (ug/L) <.51 <.51 <.51 <.51 na

Endosulfan sulfate (ug/L) <.51 <.51 <.51 <.51 na

Endrin (ug/L) <.51 <.51 <.51 <.51 2

Endrin aldehyde (ug/L) <.51 <.51 <.51 <.51 2

Endrin ketone (ug/L) <.51 <.51 <.51 <.51 2

Heptachlor (ug/L) <.51 <.51 <.51 <.51 .4

Heptachlor epoxide (ug/L) <.51 <.51 <.51 <.51 .4

Methoxychlor (ug/L) <.10 <.10 <.10 <.10 40

Toxaphene (ug/L) <.51 <.51 <.51 <.51 3

Table 8. Concentration of pesticide compounds in water from monitoring wells and seeps in the vicinity of the Nelson Landfill site.

[dup, duplicate sample; ug/L, micrograms per liter; <, denotes constituent not detected and detection limit; MCL, U.S. Environmental Protection Agency Maximum Contaminant Level; na, none available]

Locations sampled on July 27, 2005

Constituent GS1S GS1D GS2S NL3 GS3D NL4 GS4D MCL

Aldrin (ug/L) <0.48 <0.48 <0.48 <0.48 <0.48 <0.48 <0.48 na

alpha-BHC (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

beta-BHC (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

gama-BHC (lindane) (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

delta-BHC (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

alpha-Chlordane (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

gamma-Chlordane (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

Chlordane (ug/L) <.096 <.096 <.096 <.096 <.096 <.096 <.096 2

4,4’-DDD (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

4,4’-DDE (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

4,4’-DDT (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

Dieldrin (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

Endosulfan I (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

Endosulfan II (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

Endosulfan sulfate (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 na

Endrin (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 2

Endrin aldehyde (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 2

Endrin ketone (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 2

Heptachlor (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 .4

Heptachlor epoxide (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 .4

Methoxychlor (ug/L) <.096 <.096 <.096 <.096 <.096 <.096 <.096 40

Toxaphene (ug/L) <.48 <.48 <.48 <.48 <.48 <.48 <.48 3

Water Quality 27
Locations sampled on March 15, 2005

Constituent NL3 NL4 NL4 (dup) Seep MCL SMCL

Aluminum (mg/L) 0.142 <0.050 <0.050 42.6 na 0.05 to 02

Antimony (mg/L) <.050 <.050 <.050 <.050 na na

Arsenic (mg/L) <.020 <.020 <.020 <.020 0.05 na

Barium (mg/L) .038 .12 .121 .38 2 na

Beryllium (mg/L) <.005 <.005 <.005 <.005 .04 na

Boron (mg/L) <.050 .234 .241 <.050 na na

Cadmium (mg/L) <.005 <.005 <.005 <.005 .005 na

Chromium (mg/L) .011 <.010 <.010 .049 .1 na

Cobalt (mg/L) <.030 <.030 <.030 <.030 na na

Copper (mg/L) <.010 <.010 <.010 .039 1,300 na

Iron (mg/L) .219 <.010 .076 36.8 na .3

Lead (mg/L) <.050 <.050 <.050 <.050 na na

Manganese (mg/L) .012 .937 .952 .803 na .05

Molybdenum (mg/L) <.050 <.050 <.050 <.050 na na

Nickel (mg/L) <.010 .015 .016 .041 na na

Selenium (mg/L) <.020 <.020 <.020 <.020 .05 na

Silver (mg/L) <.010 <.010 <.010 <.010 na .1

Strontium (mg/L) .056 .163 .166 .172 na na

Tin (mg/L) <.050 <.050 <.050 <.050 na na

Titanium (mg/L) <.050 <.050 <.050 .978 na na

Vanadium (mg/L) <.050 <.050 <.050 .076 na na

Zinc (mg/L) <.010 <.010 <.010 .21 na na

Cyanide (mg/L) <.005 <.005 <.005 <.005 .2 na

Mercury (mg/L) <.001 <.001 <.001 <.001 .002 na

Locations sampled on July 27, 2005

Constituent GS1S GS1D GS2S NL3 GS3D NL4 GS4D MCL SMCL

Aluminum (mg/L) <0.050 <0.050 <0.050 0.059 <0.050 <0.050 <0.050 na 0.05 to 02

Antimony (mg/L) <.050 <.050 <.050 <.050 <.050 <.050 <.050 na na

Arsenic (mg/L) <.020 <.020 <.020 <.020 <.020 <.020 <.020 0.05 na

Barium (mg/L) .067 .076 .180 .039 .081 .116 .713 2 na

Beryllium (mg/L) <.005 <.005 <.005 <.005 <.005 <.005 <.005 .04 na

Boron (mg/L) <.050 <.050 <.050 <.050 .057 .237 .677 na na

Cadmium (mg/L) <.005 <.005 <.005 <.005 <.005 <.005 <.005 .005 na

Chromium (mg/L) <.010 <.010 <.010 <.010 <.010 <.010 <.010 .1 na

Cobalt (mg/L) <.030 <.030 <.030 <.030 <.030 <.030 <.030 na na

Copper (mg/L) <.010 <.010 <.010 <.010 <.010 <.010 <.010 1,300 na

Iron (mg/L) <.050 1.34 2.81 .092 .234 .055 2.26 na .3

Lead (mg/L) <.050 <.050 <.050 <.050 <.050 <.050 <.050 na na

Manganese (mg/L) .043 .032 .199 <.010 .211 .901 .217 na .05

Molybdenum (mg/L) <.050 <.050 <.050 <.050 <.050 <.050 <.050 na na

Nickel (mg/L) <.010 <.010 <.010 <.010 <.010 <.010 .012 na na

Selenium (mg/L) <.020 <.020 <.020 <.020 <.020 <.020 <.020 .05 na

Silver (mg/L) <.010 <.010 <.010 <.010 <.010 <.010 <.010 na .1

Strontium (mg/L) .056 .144 .198 .057 .193 .160 .316 na na

Tin (mg/L) <.050 <.050 <.050 <.050 <.050 <.050 <.050 na na

Titanium (mg/L) <.050 <.050 <.050 <.050 <.050 <.050 <.050 na na

Vanadium (mg/L) <.050 <.050 <.050 <.050 <.050 <.050 <.050 na na

Zinc (mg/L) .014 <.010 <.010 <.010 .013 <.010 <.010 na na

Cyanide (mg/L) <.005 <.005 <.005 <.005 <.005 <.005 <.005 .2 na

Mercury (mg/L) <.001 <.001 <.001 <.001 <.001 <.001 <.001 .002 na

Table 9. Concentration of metals and cyanide in water from monitoring wells and seeps in the vicinity of the Nelson Landfill site.

[dup, duplicate sample; mg/L, micrograms per liter; <, denotes constituent not detected and detection limit; MCL, U.S. Environmental Protection Agency Maximum Contaminant Level; SMCL, U.S. Environmental Protection Agency Secondary Maximum Contaminant Level; na, none available]

28 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Metals and Cyanide

Aluminum, chromium, copper, barium, boron, iron, 

manganese, nickel, strontium, titanium, vanadium, and 

zinc were detected in at least one of the ground-water 

samples (well or seep) collected for this investigation 

(table 9). Only barium, boron, iron, manganese, and 

strontium were detected in the samples from three or 

more wells. None of these constituents were detected 

at a concentration above its MCL for drinking water, 

although the Secondary Maximum Contaminant Level 

(SMCL) was exceeded for aluminum, iron, and manganese in at least one sample (U.S. Environmental Protection Agency, 2004). The SMCL is a non-enforceable 

standard based on aesthetic considerations such as color, 

odor, and taste. None of the remaining metal constituents were detected in any sample collected for this 

investigation. 

Aluminum was detected in the sample from well 

NL3 during the March and July 2005 sampling at a concentration of 0.142 and 0.059 mg/L, respectively (table 

9). Aluminum was not detected in any other sample 

collected for this investigation. There is no MCL for 

aluminum, but concentrations at well NL3 are within the 

range of the USEPA’s SMCL for drinking water from 

0.05 to 0.2 mg/L

Concentrations of barium in the ground-water 

samples collected for this investigation ranged from 

0.039 mg/L in well NL3 to 0.713 mg/L in well GS4D 

(table 9, fig. 10). Barium concentrations were higher in 

wells NL4 and GS4D, located directly downgradient of 

the landfill, and well GS2S located near the creek, than 

in the remaining wells. Concentrations of barium in the 

creek ranged from about 0.77 mg/L at sites SS1 and SS3 

to 0.102 mg/L at site SS2. The barium concentration in 

the creek at site SS2 was similar to the concentration in 

ground water at well GS2S (0.18 mg/L).

Concentrations of boron in the ground-water 

samples collected for this investigation ranged from 

below the detection limit in wells GS1S, GS1D, GS2S, 

and NL3 to 0.677 mg/L in well GS4D (table 9). Boron 

concentrations were consistent between sampling rounds 

at wells NL3 and NL4. Boron concentrations were 

substantially higher in wells NL4 and GS4D, located 

directly downgradient of the landfill, than in the remaining wells.

Chromium was detected in the sample from well 

NL3 during the March 2005 sampling at a concentration 

of 0.011 mg/L, approximately on order of magnitude 

below its MCL (table 9). Chromium was not detected in 

any other sample collected for this investigation, including the sample from well NL3 collected in during July 

2005.

Copper was detected in the seep sample during the 

March 2005 sampling at a concentration of 0.039 mg/L 

(table 9). Copper was not detected in any other sample 

collected for this investigation.

Concentrations of iron in the ground-water samples 

collected from the monitoring wells for this investigation ranged from below the detection limit in well GS1S 

and one of the samples collected from well NL4 to 2.81 

mg/L in well GS2S (table 9, fig. 10). These concentrations are more than an order of magnitude lower than the 

iron concentration in the seep sample. Iron concentrations showed moderate variation within and between 

sampling rounds at wells NL3 and NL4 and increased 

with depth at the GS1S/1D, NL3/GS3D, and NL4/GS4D 

well clusters. Although the value of r2 did not exceed 

0.70, iron concentrations tended to decrease as ORP and 

DO values increase, indicating that iron concentrations 

are affected by geochemical conditions in the aquifer. 

There is no MCL for iron, but many of these samples 

exceed the SMCL for drinking water of 0.3 mg/L, indicating that water-supply systems that utilize the glacial 

drift aquifer (particularly the deeper part) may need to 

treat that water to remove iron.

Concentrations of manganese in the ground-water 

samples collected for this investigation ranged from 

below the detection limit in well NL3 to more than 0.9 

mg/L in well NL4 (table 9, fig. 10). Manganese concentrations were consistent between sampling events at 

wells NL3 and NL4 and showed no consistent patterns 

with depth. There is no MCL for manganese, but many 

of these samples exceed the SMCL for drinking water of 

0.05 mg/L, indicating that water-supply systems that utilize the glacial drift aquifer may need to treat that water 

to remove manganese.

Concentrations of nickel in the ground-water 

samples collected for this investigation ranged from 

below the detection limit in most of the wells to 0.041 

mg/L at the seep (table 9). Nickel concentrations were 

moderately consistent between sampling events at wells 

NL3 and NL4. Nickel concentrations in wells NL4 and 

GS4D, located directly downgradient of the landfill, 

were higher than in the remaining samples collected 

from the monitoring wells.

Concentrations of strontium in the ground-water 

samples collected for this investigation ranged from 

about 0.056 mg/L in wells GS1S and NL3 to 0.316 mg/L 

at well GS4D (table 9, fig. 10). Strontium concentrations were consistent between sampling events at wells 

NL3 and NL4 and increased with depth at the GS1S/1D, 

NL3/GS3D and NL4/GS4D well clusters. Strontium 

concentrations in well GS4D, located directly downgradient of the landfill, were slightly higher than in the 

remaining samples collected from the monitoring wells. 

Strontium concentrations showed a high degree of 

positive correlation with chloride concentrations (table 

5) regardless of whether wells NL4 and GS4D were 

included in the analysis, indicating strontium may be 

partly derived from road salts (Granato, 1996).

Water Quality 29
Figure 10. Concentration of selected metals in samples from monitoring wells in the vicinity of the Nelson Landfill site, July 27, 2005.

30 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois
Titanium was detected in the seep sample during the 

March 2005 sampling at a concentration of 0.978 mg/L 

(table 9). Titanium was not detected in any other sample 

collected for this investigation.

Vanadium was detected in the seep sample during 

the March 2005 sampling at a concentration of 0.076 

mg/L (table 9). Vanadium was not detected in any other 

sample collected for this investigation.

Zinc was detected in the seep during the March 

2005 sampling at a concentration of 0.21 mg/L and was 

detected during the July 2005 sampling in wells GS1S 

and GS3D at concentrations of 0.014 and 0.013 mg/L, 

respectively (table 9). Zinc concentrations were consistent at wells NL3 and NL4 between sampling events and 

showed no patterns with depth or location.

Cyanide was not detected in any sample collected 

as part of this investigation (table 9). Cyanide was not 

detected in any of the samples collected from the creek 

(Gordon Stevens, Civil and Environmental Consultants 

Inc., written commun., 2005). The absence of detectable concentrations of cyanide from wells where it had 

been detected during a prior investigation (Ecology 

and Environment, Inc., 1991) is further indication that 

natural attenuation processes have reduced cyanide concentrations in this aquifer in the years since the previous 

investigations were performed. 

SUMMARY AND CONCLUSIONS

The U.S. Geological Survey, in cooperation with 

the United City of Yorkville and the U.S. Environmental 

Protection Agency, characterized the geology, hydrology, and water quality of the glacial drift aquifer in the 

Newark Bedrock Valley in the vicinity of the Nelson 

Landfill site in Yorkville, Illinois. The investigation was 

performed to evaluate the potential for development of 

the aquifer as a water-supply source and the effect of 

land use, including landfill operations, on the quality of 

water in the aquifer. 

There are two geologic deposits of concern in the 

study area-a shallow deposit composed primarily of 

silt and clay till, and a deeper sand-and-gravel deposit. 

The sand-and-gravel deposit constitutes the glacial drift 

aquifer, which is from about 35 to greater than 85 feet 

thick and has a geometric mean horizontal hydraulic 

conductivity of 9.2 feet per day. The aquifer appears to 

be sufficiently permeable for use as a source of publicwater supply, but because the geology is heterogeneous, 

the development of the aquifer for water supply would 

require site-specific studies to optimally locate any 

public-supply well or well field. The overall direction of 

flow in the aquifer is from north to south, with a slight 

west to east component toward the tributary to Rob Roy 

Creek. The creek appears to be in good hydraulic connection with the glacial drift aquifer so that the flow of 

the creek could be affected (reduced) by any future highcapacity pumping from the aquifer. Ground-water velocity and the volume of ground water flowing through the 

aquifer were calculated to be about 7.7 X 10-2 feet per 

day and 2,300 cubic feet per day, respectively.

There is no indication that the water in the aquifer 

in the vicinity of the site contains concentrations of any 

constituent high enough to represent a threat to human 

health or the environment. Contaminants of potential 

concern detected during ground-water sampling in 

the mid-1990s, including volatile organic compounds, 

pesticide compounds, and cyanide, were not detected 

in samples of ground water collected during this investigation. No constituent, including nitrate as nitrogen 

and metals, was detected above its U.S. Environmental 

Protection Agency Maximum Contaminant Level. However, iron, manganese, and aluminum were detected at 

concentrations above their Secondary Maximum Contaminant Level in at least one sample, indicating that this 

water may require treatment if used for public-water supply. There is no indication that water quality in the creek 

is being degraded by the inflow of ground water.

Of the major ions, nitrogen compounds, and metals 

detected in the ground water beneath the study area, the 

highest concentration of magnesium, sodium, potassium, alkalinity, chloride, ammonia as nitrogen, barium, 

boron, manganese, nickel, and strontium were detected 

in the sample from two wells located directly downgradient of the landfill. Nitrogen as nitrate also was detected 

in a shallow well located upgradient of the landfill at a 

concentration below its Maximum Contaminant Level, 

indicating that agricultural practices may be affecting the 

concentrations of nitrogen compounds in the glacial drift 

aquifer.

Oxidation-reduction conditions in the glacial drift 

aquifer become more reducing with depth. This change 

is reflected by the type and concentration of the nitrogen 

compounds and the concentration of dissolved oxygen 

and iron in the glacial drift aquifer. Concentrations of 

some of the major ions and metals may be affected by 

dissolution of carbonate minerals and possibly road salts.

Literature Cited

Balding, G.O., 1991, Changes in chloride concentration in 

water from municipal wells that tap aquifers in rocks of 

Cambrian and Ordovician age in northeastern Illinois, 1915-

84: U.S. Geological Survey Water-Resources Investigations 

Report 90-4116, 52 p.

Summary and Conclusions  31
 Bouwer, H., and Rice, R.C., 1976, A slug test for determining hydraulic conductivity of unconfined aquifers with 

completely or partially penetrating wells: Water Resources 

Research, v. 12, no. 3, p. 423-429.

Burch, Stephen, 2002, A comparison of potentiometric 

surfaces for the Cambrian-Ordovician aquifer, 1995-2000: 

Illinois State Water Survey Data/Case Study 2002-02, 63 p.

Ecology and Environment, Inc., 1986, Hydrogeologic report 

on the Yorkville/Nelson Landfill, Yorkville, Illinois: 

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Chicago, Illinois, [variously paged].

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Yorkville, Illinois: Prepared for the U.S. Environmental 

Protection Agency, Chicago, Illinois, [variously paged].

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results, Nelson Landfill, Yorkville, Illinois: Prepared for the 

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[variously paged].

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Prepared for the U.S. Environmental Protection Agency, 

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Granato, G.E., 1996, Deicing chemicals as a source of constituents in highway runoff: Transportation Research Record 

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Hansel, A.K., and Johnson, W.H., 1996, Wedron and Mason 

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van der Kamp, 1976, Determining aquifer transmissivity by 

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Survey Circular 460, 77 p.

32 Geology, Hydrology, and Water Quality of the Glacial Drift Aquifer in the Vicinity of the Nelson Landfill near Yorkville, Illinois