DOE/ID-22187

SPATIAL VARIABILITY OF SEDIMENTARY 

INTERBED PROPERTIES NEAR THE IDAHO 

NUCLEAR TECHNOLOGY AND ENGINEERING 

CENTER AT THE IDAHO NATIONAL 

ENGINEERING AND ENVIRONMENTAL 

LABORATORY, IDAHO

U.S. GEOLOGICAL SURVEY

WATER-RESOURCES INVESTIGATIONS REPORT 03-4142

Prepared in cooperation with the U.S. DEPARTMENT OF ENERGY
SPATIAL VARIABILITY OF SEDIMENTARY 

INTERBED PROPERTIES NEAR THE IDAHO 

NUCLEAR TECHNOLOGY AND ENGINEERING 

CENTER AT THE IDAHO NATIONAL 

ENGINEERING AND ENVIRONMENTAL 

LABORATORY, IDAHO

By Kari A. Winfield

________________________________________________________________________

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03-4142

Prepared in cooperation with the

U.S. DEPARTMENT OF ENERGY

Idaho Falls, Idaho

June 2003
ii

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

Any use of trade, product, or firm names in this publication is for descriptive

purposes only and does not constitute endorsement by the U.S. Government.

For additional information write to: Copies of this report can be

purchased from:

U.S. Geological Survey U.S. Geological Survey

INEEL, MS 1160 Information Services

P.O. Box 2230 Box 25286, Federal Center

Idaho Falls, ID 83403 Denver, CO 80225
iii

CONTENTS

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

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Previous investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Geohydrologic setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Field and laboratory methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Drilling and core collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Hydraulic properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Saturated hydraulic conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Unsaturated hydraulic properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Bulk properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Bulk density, particle density, and porosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Particle-size distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Specific surface area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Laboratory measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

35-m, 45-m, and 55-m interbeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Spatial variation of interbed properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Baked-zone intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

References cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

FIGURES

Figure 1. Map showing location of the Idaho National Engineering and Environmental Laboratory, Idaho 

and selected facilities, including the Idaho Nuclear Technology and Engineering Center. . . . . 3

Figure 2. Map showing location of the Vadose Zone Research Park relative to the Idaho Nuclear 

Technology and Engineering Center, Idaho National Engineering and Environmental 

Laboratory, Idaho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 3. Map showing borehole locations within the Vadose Zone Research Park at the Idaho National 

Engineering and Environmental Laboratory, Idaho. Cross section A-A’ shows location and 

thickness of basalt and sedimentary intervals within selected boreholes . . . . . . . . . . . . . . . . . . 5

Figure 4. Graph showing water content as a function of matric pressure, measured using the steadystate centrifuge method, for 10 sedimentary interbed core samples . . . . . . . . . . . . . . . . . . . . 14

Figure 5. Graph showing hydraulic conductivity as a function of water content, measured using the 

steady-state centrifuge method, for 10 sedimentary interbed core samples . . . . . . . . . . . . . . 15

Figure 6. Graph showing cumulative particle-size distributions on a percent-finer-than basis for 

10 sedimentary interbed core samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 7. Graphs showing geometric mean particle diameter for 90 samples plotted with depth

below surface for (a) the 35-m interbed, (b) the 45-m interbed, and (c) the 55-m interbed . . . 18

Figure 8. Graphs showing geometric particle-size standard deviation for 90 samples plotted with 

depth below surface for (a) the 35-m interbed, (b) the 45-m interbed, and (c) the 55-m

interbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 9. Graphs showing frequency distribution of 90 samples within the 35-m, 45-m, and 55-m 

interbeds, based on (a) geometric mean particle diameter, and (b) geometric standard 

deviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
iv

Figure 10. Graphs showing saturated hydraulic conductivity for 22 core samples plotted with depth 

below land surface for (a) the 35-m interbed, (b) the 45-m interbed, and (c) the 55-m 

interbed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 11. Graphs showing comparison of unsaturated hydraulic properties measured on core 

samples from baked-zone intervals defined in the 35-m, 45-m, and 55-m interbeds. 

(a) water content as a function of matric pressure. (b) hydraulic conductivity as a 

function of water content. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

TABLES

Table 1. Measured values of bulk density, particle density, and porosity for 10 core samples . . . . . . . . 28

Table 2. Saturated hydraulic conductivity determined by the falling-head method and the associated

saturated water content for 10 core samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table 3. Unsaturated hydraulic property measurements for 10 core samples . . . . . . . . . . . . . . . . . . . . . 29

Table 4. Textural class percentages and nomenclature using the U.S. Department of Agriculture’s

soil classification system for 76 bulk and core samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Table 5. Specific surface areas for 10 core samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Table 6. Comparison of particle-size statistics between baked and non-baked sediment . . . . . . . . . . . . 36

CONVERSION FACTORS, ABBREVIATED UNITS, AND VERTICAL DATUM

Multiply By To Obtain

millimeter (mm) 0.03937 inch (in)

centimeter (cm) 0.3937 inch (in)

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

square centimeter (cm2) 0.155 square inch (in2)

square meter (m2) 10.76 square foot (ft2)

square kilometer (km2) 0.3861 square mile (mi2)

cubic centimeter (cm3) 0.06102 cubic inch (in3)

cubic meter (m3) 35.31 cubic foot (ft3)

million cubic meters (106 m3) 810.7 acre-foot (acre-ft)

milliliter (ml) 0.03382 fluid ounce (fl. oz)

gram (g) 0.03527 ounce (oz)

dyne 2.248×10-6 pound-force (lb-f)

centimeters of water (cm-water) 0.01419 pound per square inch (lb/in2)

gram per cubic centimeter (g/cm3) 64.4220 pound per cubic foot (lb/ft3)

Temperature: Degrees Celsius (oC) can be converted to degrees Fahrenheit (oF) by using the formula oF = [1.8 ×

(oC)] + 32. Degrees Kelvin (K) can be converted to oF by the relation oF = [1.8 × (K - 273)] + 32.

Sea level: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929, formerly 

called “Sea-Level Datum of 1929”), which is derived from a general adjustment of the first-order leveling networks 

of the United States and Canada.

Abbreviated units used in report: cm/s (centimeters per second), rad/s (radians per second), cm3/s (cubic centimeters 

per second), ml/hr (milliliter per hour), m2/g (meters squared per gram).

Acceleration due to gravity is abbreviated g, and is taken to equal 980.7 cm/s2.
1

Spatial Variability of Sedimentary Interbed 

Properties near the Idaho Nuclear Technology and 

Engineering Center at the Idaho National 

Engineering and Environmental Laboratory, Idaho

by Kari A. Winfield

Abstract

The subsurface at the Idaho National Engineering and Environmental Laboratory (INEEL) is 

complex, comprised primarily of thick, fractured 

basalt flows interbedded with thinner sedimentary 

intervals. The unsaturated zone can be as thick as 

200 m in the southwestern part of the INEEL. The 

Vadose Zone Research Park (VZRP), located 

approximately 10 km southwest of the Idaho 

Nuclear Technology and Engineering Center 

(INTEC), was established in 2001 to study the 

subsurface of a relatively undisturbed part of the 

INEEL. Waste percolation ponds for the INTEC 

were relocated to the VZRP due to concerns that 

perched water within the vadose zone under the 

original infiltration ponds (located immediately 

south of the INTEC) could contribute to migration 

of contaminants to the Snake River Plain aquifer.

Knowledge of the spatial distribution of texture and hydraulic properties is important for 

developing a better understanding of subsurface 

flow processes within the interbeds, for example, 

by identifying low permeability layers that could 

lead to the formation of perched ground-water 

zones. Because particle-size distributions are easier to measure than hydraulic properties, particle 

size serves as an analog for determining how the 

unsaturated hydraulic properties vary both vertically within particular interbeds and laterally 

within the VZRP. As part of the characterization 

program for the subsurface at the VZRP, unsaturated and saturated hydraulic properties were measured on 10 core samples from six boreholes. Bulk 

properties, including particle size, bulk density, 

particle density, and specific surface area, were 

determined on material from the same depth intervals as the core samples, with an additional 66 particle-size distributions measured on bulk samples 

from the same boreholes. 

From lithologic logs of the 32 boreholes at the 

VZRP, three relatively thick interbeds (in places 

up to 10 m thick) were identified at depths of 35, 

45, and 55 m below land surface. The 35-m interbed extends laterally over a distance of at least 900 

m from the Big Lost River to the new percolation 

pond area of the VZRP. Most wells within the 

VZRP were drilled to depths less than 50 m, making it difficult to infer the lateral extent of the 

45-m and 55-m interbeds. The 35-m interbed is 

uniform in texture both vertically and laterally; the 

45-m interbed coarsens upward; and the 55-m 

interbed contains alternating coarse and fine layers. Seventy-one out of 90 samples were silt loams 

and 9 out of 90 samples were classified as either 

sandy loams, loamy sands, or sands. The coarsest 

samples were located within the 45-m and 55-m 

interbeds of borehole ICPP-SCI-V-215, located 

near the southeast corner of the new percolation 

pond area. 

At the tops of some interbeds, baked-zone 

intervals were identified by their oxidized color 

(yellowish red to red) compared to the color of the 

underlying non-baked material (pale yellow to 

brown). The average geometric mean particle 

diameter of baked-zone intervals was only slightly 

coarser, in some cases, than the underlying nonbaked sediment. This is likely due to both depositional differences between the top and bottom of 

the interbeds and the presence of small basalt 

clasts in the sediment. Core sample hydraulic 

properties from baked zones within the different 

interbeds did not show effects from alteration 

caused during basalt deposition, but differed 

mainly by texture.
2

Saturated hydraulic conductivities (Ksat) for the 

10 core samples ranged from 10-7 to 10-4 cm/s. 

Low permeability layers, with Ksat values less than 

10-7 cm/s, within the 35-m and 45-m interbeds 

may cause perched ground-water zones to form 

beneath the new percolation pond area, leading to 

the possible lateral movement of water away from 

the VZRP.

INTRODUCTION

The Idaho Nuclear Technology and Engineering Center (INTEC), formerly known as the Idaho 

Chemical Processing Plant (ICPP), is located in 

the southwestern part of the INEEL covering an 

area of approximately 0.8 km2

 (figs. 1 and 2). 

Between 1952 and 1984, organic and chemical 

wastes produced on site were disposed of in a 183-

m-deep injection well, which penetrated the Snake 

River Plain aquifer. Wastes produced after 1984 

were disposed of in two infiltration ponds located 

directly south of the facility (fig. 2). The first infiltration pond was completed in February 1984 and 

used through October 1985. The second pond was 

constructed immediately west of the first pond in 

October 1985 and used through at least 1995. An 

annual average of 1.6 million m3 (430 million gallons) of wastewater was discharged to the deep 

injection well and the infiltration ponds between 

1963 and 1993. An average annual discharge of 

2.2 million m3 (570 million gallons) was delivered 

to the ponds between 1992 and 1995 (Cecil and 

others, 1991). The primary chemical components 

of waste discharged to the ponds from 1992 to 

1995 included chloride, fluoride, nitrate, sodium, 

and sulfate, with more than 90 percent of the 

radioactivity in pond wastewater attributed to tritium. Water samples collected from wells penetrating the aquifer and perched water zones contained 

radioisotopes of strontium, cesium, americium, 

plutonium, and hydrogen (Cecil and others, 1991; 

Bartholomay and others, 1997; Bartholomay, 

1998) as a result of waste disposal practices. 

The change from deep injection to infiltration 

ponding led to the formation of perched water 

zones beneath the ponds between 1984 and 1988. 

Lithologic features attributed to controlling these 

zones included low permeability sedimentary 

units; dense, unfractured basalt; altered basalt 

zones created during emplacement of an overlying 

flow (referred to as interflow baked zones); and 

sediment and chemical infilling of fractures where 

sediments overlie basalt units. Perching likely 

occurred due to the presence of reduced vertical 

permeability zones in the subsurface and the high 

volumes of water discharged to the ponds (Cecil 

and others, 1991). 

The 3-km2 Vadose Zone Research Park 

(VZRP) was established in 2001 to study the subsurface hydrology and geochemistry of a relatively undisturbed and uncontaminated area of the 

INEEL (fig. 2). Concerns that perched water 

within the vadose zone under the original infiltration ponds at the INTEC could contribute to 

migration of contaminants to the Snake River 

Plain aquifer led to the construction of two new 

percolation ponds approximately 9.5 km southwest of the INTEC facility. The relocation of the 

percolation ponds prompted the development of 

the VZRP in order to thoroughly characterize the 

subsurface, so that as the ponds went online, water 

moving through the subsurface could be monitored and studied. The VZRP will also serve as an 

area to conduct intermediate- to large-scale hydrologic experiments. The new ponds are scheduled 

to receive approximately 4,000 m3

 (1 million gallons) of equipment cooling water each day (Bechtel BWXT Idaho, LLC, 2003). 

Previous Investigations

Little work has been done to characterize the 

unsaturated hydraulic properties of the sedimentary interbeds in the vicinity of the INTEC. Most 

of the solute transport modeling and measurement 

of hydraulic properties at the INEEL have been 

conducted near the Radioactive Waste Management Complex (fig. 1), where potential migration 

of shallow, buried hazardous waste through the 

unsaturated zone poses concern for Snake River 

Plain aquifer quality. Perkins (2003) presents bulk 

and unsaturated hydraulic property measurements 

for borehole ICPP-SCI-V-215 (fig. 3), located near 

the southeast margin of the new percolation pond 

area for the INTEC facility. Additional information about the subsurface, such as stratigraphic and 

geophysical data for wells near the INTEC, is pre-
3

Figure 1. Location of the Idaho National Environmental and Engineering Laboratory, Idaho and 

selected facilities, including the Idaho Nuclear Technology and Engineering Center.
4

Figure 2. Location of the Vadose Zone Research Park (VZRP) relative to the Idaho Nuclear 

Technology and Engineering Center (INTEC) and the Big Lost River at the Idaho National 

Engineering and Environmental Laboratory, Idaho (adapted from the U.S. Geological 

Survey, 1:24,000 Circular Butte 3 SW quadrangle (1973)). Shown are the former INTEC 

percolation ponds, located adjacent to the facility, and the new INTEC percolation pond

area within the VZRP.
5

Figure 3. Borehole locations within the Vadose Zone Research Park at the Idaho National Engineering and Environmen

Idaho (adapted from Bechtel BWXT Idaho, LLC, 2002). Cross section A-A' shows location and thickness of b

sedimentary intervals within selected boreholes. Locations of core samples analyzed for unsaturated hydraulic 

indicated.
6

Figure 3. Borehole locations within the Vadose Zone Research Park at the Idaho National Engineering and Environmenta

(adapted from Bechtel BWXT Idaho, LLC, 2002). Cross section A-A' shows location and thickness of basalt anintervals within selected boreholes. Locations of core samples analyzed for unsaturated hydraulic properties are 

indicated—Continued.
7

sented by Anderson (1991), Anderson and others 

(1996), and Bechtel BWXT Idaho, LLC (2002).

Purpose and Scope

This report investigates the spatial variability of 

sedimentary interbed properties measured on core 

samples from multiple boreholes near the INTEC. 

Knowledge of the spatial distribution of texture 

and hydraulic properties is important for developing a better understanding of subsurface flow processes within the interbeds, for example, by 

identifying low permeability layers that could lead 

to perching. This type of data is also needed for 

developing flow and transport models. One goal of 

the INEEL-Department of Energy contractor, 

Bechtel BWXT Idaho, LLC, is to correlate the 

hydraulic and bulk properties of the sedimentary 

interbeds with their measured geochemical properties in an attempt to delineate possible preferential 

pathways for subsurface solute transport. The 

establishment of the VZRP provides a unique 

opportunity to compare laboratory measurements 

of unsaturated hydraulic properties with temporal 

field measurements collected from instruments 

emplaced at comparable depths to where the core 

samples were collected. Detailed particle-size 

information will be useful for applying similarmedia scaling (Miller and Miller, 1956; Miller, 

1980; Nimmo and others, 2002a) to laboratorydetermined hydraulic properties or predicting 

unsaturated hydraulic properties from more easily 

measured bulk properties, using transfer functions 

being developed by scientists at the U.S. Geological Survey (USGS), Menlo Park, CA, or those 

described in the literature (Arya and Paris, 1981; 

Schaap, 1999). 

Hydraulic and bulk properties were measured 

on samples from boreholes ICPP-SCI-V-189, 

-198, -204, -205, -213, and -214 drilled by a subcontractor to the INEEL-DOE contractor BechtelBWXT Idaho, LLC and by the USGS in 2000 and 

2001. Core sections were collected from three sedimentary interbeds starting at approximately 35, 

45, and 55 m below land surface. Because one 

goal of Bechtel BWXT Idaho, LLC is to compare 

laboratory and field measurements of hydraulic 

properties, 1- to 2-foot core sections located at 

depths comparable to borehole monitoring instruments were selected by Bechtel BWXT Idaho, 

LLC and sent to the USGS in Menlo Park, CA. 

The least disturbed intervals were used to re-core 

smaller samples into the appropriate retainers used 

with the steady-state centrifuge method (Nimmo 

and others, 1994; Conca and Wright, 1998; 

Nimmo and others, 2002b) for measurement of 

unsaturated hydraulic properties. Saturated 

hydraulic conductivity, saturated water content, 

hydraulic conductivity as a function of water content (K(θ)) and water retention (θ(ψ)) were measured on 10 re-cored samples. Particle size, bulk 

density, particle density, and specific surface area 

were analyzed on core trimmings saved during 

sample re-coring. In order to determine the spatial 

variability of texture within the interbeds, an additional 66 particle-size distributions were measured 

on bulk samples taken from the longer core sections between the depths of 36 and 57 m, with an 

average of 13 samples per meter of core received. 

Acknowledgments

The author wishes to thank Bechtel BWXT 

Idaho, LLC, for providing funding for the laboratory portion of this study.

GEOHYDROLOGIC SETTING

The INEEL occupies about 2,300 km2 in an 

active mountain building province on the eastern 

Snake River Plain, a northern extension of the 

Basin and Range Province. The eastern Snake 

River Plain is a northeast trending basin, approximately 320 km long and 80 to 110 km wide, which 

slopes gently to the southwest and is bordered by 

northwest trending mountain ranges. Although the 

area is relatively aseismic, active faults bound 

these ranges and are involved in their uplift.

The eastern Snake River Plain is underlain by 

interbedded volcanic and sedimentary units that 

extend for up to 3000 m below the surface. The 

sedimentary layers represent quiet intervals 

between volcanic eruptions and are primarily of 

eolian, fluvial, and lacustrine origin with large 

amounts of silt, clay, and sand. Volcanic units, 

comprised primarily of basalt flows, welded ash 

flows, and rhyolite, may be vesicular to massive 

with either horizontal or vertical fracture patterns. 
8

Near the INTEC facility, wells drilled to 200-m 

depths penetrate a sequence of 23 basalt-flow 

groups and 15 to 20 sedimentary interbeds (Anderson, 1991). The surficial sediments near the 

INTEC consist of gravelly alluvium and range 

from 2- to 20-m thick, being thickest to the northwest (Anderson and others, 1996, figure 7).

The climate of the eastern Snake River Plain is 

semi-arid with an average annual precipitation of 

22 cm. Portions of the Snake River Plain aquifer 

underlie the INEEL. The depth to the water table 

ranges from 60 m in the northern part of INEEL to 

about 200 m toward the south (Barraclough and 

others, 1981; Liszewski and Mann, 1992). The 

predominant direction of ground-water flow is 

from northeast to southwest. Recharge to the aquifer is primarily from irrigation water diversions 

from streams; precipitation and snowmelt; underflow from streams; and seepage from surface 

water bodies (Hackett and others, 1986). The Big 

Lost River is an intermittent stream, which flows 

from southwest to northeast about 2.5 km north of 

the new percolation pond area at the INTEC (figs. 

2 and 3). The depth to the water table beneath the 

new percolation ponds is approximately 145 m. A 

perched water zone has been detected at depths of 

35 to 45 m below the new percolation pond area, 

likely caused by the presence of a low-permeability sedimentary interbed. Waste water exiting the 

ponds could potentially migrate over large distances within this laterally continuous interbed 

(Bechtel BWXT Idaho, LLC, 2002). 

FIELD AND LABORATORY METHODS

Drilling and Core Collection

Most boreholes were drilled at the VZRP by a 

subcontractor of Bechtel BWXT Idaho, LLC, with 

the exception of ICPP-SCI-V-214 and -215, which 

were drilled by the USGS. Twenty-eight boreholes were completed in the vadose zone (fig. 3) 

and four boreholes were completed in the Snake 

River Plain aquifer. The boreholes were drilled 

between February 2000 and June 2001 using a 

reverse rotary drilling method. For most holes, air 

was used as the drilling fluid; water was used in 

drilling boreholes to lubricate the core barrel. 

Boreholes ICPP-SCI-V-189, -192, -195, -198, 

-204, -205, and -207 were instrumented with 

advanced tensiometers, suction lysimeters, water 

content sensors, and soil gas sampling ports at 

selected depths. Borehole ICPP-SCI-V-214 was 

instrumented with tensiometers, lysimeters, and 

gas ports, and ICPP-SCI-V-215 was instrumented 

with tensiometers and gas ports only. Instrumented boreholes were backfilled with layers of 

granular bentonite, sand, and silica flour. Core 

samples were collected in 6.4- and 8.9-cm-diameter Lexan1 liners at select intervals. Core material 

analyzed in this study originated from holes ICPPSCI-V-189, -198, -204, -205, -213, and -214.

The majority of the vadose-zone boreholes 

were completed to depths ranging from 40 to 50 m 

below land surface. Seven shallow boreholes 

(ICPP-MON-S-187, -190A, -193, -196, -199, -203, 

and -210) do not penetrate beneath the first basalt 

layer (or greater than about 15 m). Six of the 

vadose-zone boreholes (ICPP-SCI-V-201A, -209, 

-213, -214, -215, and ICPP-MON-V-212) were 

completed to depths greater than 50 m. The four 

aquifer wells (ICPP-MON-A-164C, -165, -166, 

and -167; not shown in figure 3) were completed 

to depths ranging between 160 and 180 m. 

Sample Preparation

Ten 0.3- to 0.6-m long core sections from 

seven boreholes, at depths ranging from 36.5 to 

56.4 m (fig. 3), were received by scientists at the 

USGS, Menlo Park, CA. Subsections of these 

cores were chosen for bulk and hydraulic property 

analysis. Most of the sections were disturbed to 

some degree, as evidenced by the presence of significant fractures along the lengths of the cores, 

shrinkage of the material away from the liner 

walls, or looseness of the material within the core 

liners. The main consequence of this disturbance 

was difficulty in selecting intact core intervals for 

use in measuring unsaturated hydraulic properties 

by the steady-state centrifuge method (Nimmo 

and others, 1994; Conca and Wright, 1998; 

Nimmo and others, 2002b). Bulk density values 

1

The use of product or company names does 

not signify their endorsement by the U.S. 

Geological Survey.
9

are not likely to be representative of field conditions due to this disturbance.

Because the steady-state centrifuge method 

requires the use of special sample holders, it was 

first necessary to select intervals suitable for recoring into the appropriate centrifuge retainers. 

The best possible intervals were chosen based on 

the appearance of the material through the transparent plastic (Lexan1) core liners. Intervals with 

the fewest number of fractures or that appeared 

most undisturbed and cohesive were selected for 

re-coring. Shorter, typically 10-cm-long, core sections were created by cutting the liners perpendicular to their lengths using an electric rotary hand 

tool. To aid in separating the shorter sections from 

the longer sections after cutting through the liners, 

a wetting solution (0.3 ml sodium hypochlorite per 

liter tap water) was applied to the cuts using a 

squirt bottle. Samples for the centrifuge method 

were then collected using a re-coring machine 

designed specifically for minimal disturbance sampling. With the core liner held stationary, a piston 

pushes material vertically out of the liner while a 

sharp-edged metal sleeve that houses the centrifuge retainer (located above the core section) 

shaves the excess material away. Core trimmings 

were saved for later determination of bulk properties, such as specific surface area, particle density, 

and particle-size distribution.

Most of the core sections were dry upon their 

arrival in Menlo Park and, because of their high 

silt and clay content, very hard. The section from 

borehole ICPP-SCI-V-214, at 43.75 to 44.36 m 

depth, appeared to have the highest initial water 

content. Due to the hardness and dryness of most 

of the cores, it was necessary to wet the 10-cmlong intervals before re-coring them into the centrifuge sample retainers by submerging them in a 

dish of the wetting solution. 

Hydraulic Properties

Saturated hydraulic conductivity

Prior to measurement of saturated hydraulic 

conductivity (Ksat), each sample in its centrifuge 

retainer was immersed to its top in a dish of the 

deaerated wetting solution and wetted to apparent 

saturation. A wetting solution concentration of 

0.3 ml sodium hypochlorite per liter of tap water 

was used throughout the experiments, including 

during the determination of unsaturated hydraulic 

conductivity, in order to inhibit bacterial growth 

within the soil pores. Saturated water content was 

calculated on a volume basis by subtracting the 

oven-dry weight of the core from the wet weight 

(using the sample weight determined immediately 

following the Ksat experiment) and dividing by the 

sample volume in the centrifuge retainer.

Two methods were used for Ksat measurement 

(1) the standard falling-head method (Klute and 

Dirksen, 1986) and (2) a falling-head method 

adapted for use with a centrifuge (Nimmo and 

Mello, 1991; Nimmo and others, 2002b). The centrifuge method uses a centrifugal acceleration of 

approximately 9 g (calculated at the sample midpoint) in addition to gravity to drive flow through 

the sample. This method is useful when Ksat values are expected to be low because samples can 

reach steady-state conditions more quickly. Saturated hydraulic conductivity (cm/s) using the traditional falling-head method is calculated by:

where a is the cross-sectional area of the burette 

(cm2), A is the cross-sectional area of the sample 

(cm2), L is the sample length (cm), Hi

 and Hf are 

the initial and final heights of water in the burette 

(cm), and ∆t (s) is the time it takes for the burette 

level to drop from Hi

 to Hf. H is defined as the distance between the bottom of the sample and the 

position of the water meniscus in the burette. Ksat

(cm/s) by the centrifuge falling-head method is 

calculated by:

where g is the gravitational acceleration (cm/s), ω

is the centrifuge speed (rad/s), and rb is the radius 

to the bottom of the sample from the center of the 

centrifuge rotor (cm). Here, Hi and Hf

 are defined 

as the initial and final distances between the water 

level recorded in a burette and the plane in which 

the sample spins in the centrifuge. Steady-state 

∆

-------- ⎝ ⎠ ⎛ ⎞ -----

⎝ ⎠ ⎜ ⎟ ⎛ ⎞ =

∆

-------- ⎝ ⎠ ⎛ ⎞ + ω

+ ω

-----------------------------------

⎝ ⎠ ⎜ ⎟ ⎜ ⎟ ⎛ ⎞

=
10

conditions are achieved when the fluid volume 

entering the sample equals the effluent volume.

Unsaturated hydraulic properties

The steady-state centrifuge (SSC) method 

(Nimmo and others, 1994; Conca and Wright, 

1998; Nimmo and others, 2002b) involves using 

centrifugal force to desaturate samples and define 

the unsaturated hydraulic conductivity relations, 

K(θ) and K(ψ). Darcy’s law with the gravitational 

force term replaced by a centrifugal force term is:

where Q is the pump flow rate (cm3/s), A is the 

cross-sectional area of the sample (cm2), Kv is the 

unsaturated hydraulic conductivity per unit volume (cm3 s/g), ψv is the matric potential per unit 

volume (dynes/cm2

), ρw is the density of water (g/

cm3

), ω is the angular velocity of the centrifuge 

(rad/s), and r is the radius from the center of the 

centrifuge rotor to the midpoint of the sample 

(cm). If the centrifugal driving force is applied 

such that ω is large enough to ensure dψv/dr << 

ρwω2r, then any matric potential gradients that 

develop are insignificant and flow is essentially 

driven by centrifugal force alone. Kv(ψv) is then 

approximated by Q/(Aρwω2

r). Converting to units 

of pressure head (energy per unit weight), where 

, this relation becomes: 

with Kw expressed in cm/s and ψw expressed in 

cm-water, and where g is the acceleration due to 

gravity, or 980.7 cm/s2. (Note that in the remainder of the text, the subscript ‘w’ will be dropped 

when referring to matric pressure (ψ)). The unsaturated hydraulic conductivity points that define the 

K(θ) relation can then be determined by varying 

the centrifuge speed and pump flow rate until a 

constant water content is achieved.

A Beckman1 model J-6M ultracentrifuge with 

an Unsaturated Flow Apparatus1

 (UFA) rotor 

(Conca and Wright, 1998) was used in the SSC 

method. Infusion pumps were used to deliver flow 

rates greater than 0.1 ml/hr, while a syringe pump 

was used to achieve flow rates as low as 0.01 ml/

hr. Unsaturated K values ranging from 10-10 to 10-4

cm/s can be achieved with the SSC method. Two 

samples of similar texture were run simultaneously, starting from saturation (as determined by 

the falling-head methods described above) and 

desaturating in increments determined by varying 

the pump rate and centrifuge speed. The steadystate criterion was achieved when the sample 

weight remained constant after repeated spinning 

of the centrifuge at the same speed and using the 

same pump flow rate.

After determining the steady-state water content associated with a given unsaturated hydraulic 

conductivity, the sample was removed from the 

centrifuge to measure the equilibrium matric pressure (ψ) using a tensiometer or a filter paper. Pairing the average water content (θ) of the sample 

with the equilibrium pressure yielded a point on 

the water retention curve (θ(ψ)). ψ is zero at complete saturation and becomes increasingly more 

negative as the sample desaturates. A tensiometer 

was used to measure pressures higher than -700 

cm-water. At lower (more negative) pressures, air 

in the tensiometer comes out of solution and 

expands, causing errors in the ψ measurement. For 

ψ < -700 cm-water, the filter paper method was 

used. Whatman1 No. 42 filters, 3.33 cm diameter, 

were chosen because of the availability of published retention curves for this filter type. The formulas used to determine the matric pressure 

associated with the gravimetric water content (F) 

of the filter paper are those of Fawcett and CollisGeorge (1967) as stated by Greacen and others 

(1987). For F < 0.453:

and for F > 0.453:

with ψ expressed in cm-water. A single filter 

paper was placed in contact with the top of the 

sample, using a foil-wrapped stopper to make 

good contact between the sample surface and the 

filter. The sample was then wrapped in plastic and 

foil to prevent evaporation. Each sample was 

--

ψ

--------- – ρ ω ⎝ ⎠ ⎛ ⎞ = = –

≡ ρ

( ) ψ

ω

≈ ------------

ψ = - ( ) –

ψ = - ( ) –
11

allowed to equilibrate with the filter paper for at 

least 3 days—the midpoint of the equilibration 

periods indicated in the literature (Fawcett and 

Collis-George, 1967; Hamblin, 1981; Chandler 

and Gutierrez, 1986; and Greacen and others; 

1987). 

Bulk Properties

Bulk density, particle density, and porosity

Bulk density (ρb) was determined by dividing 

the oven-dry weight of the re-cored sample by the 

total volume. The total volume was calculated 

from the dimensions of the centrifuge retainer 

(3.33 cm diameter and 4.9 cm length, on average), 

with the sample length adjusted for a top recess. 

Recesses were estimated by taking an average of 

several measurements over the sample surface 

with a depth micrometer. The particle density for 

each sample (ρs) was measured by the pycnometer method, after Blake and Hartge (1986), using 

representative splits of the air-dried core trimmings. Total porosity (Φ) was then calculated 

from the relation Φ = 1 – (ρb /ρs). Initial bulk density and porosity (ρbi and Φi

) values represent the 

state of the samples prior to measurement of unsaturated hydraulic properties in the centrifuge. Final 

values (ρbf and Φf

) were calculated after all centrifuge and water retention measurements were completed.

Particle-size distribution

Prior to particle-size determination, the trimmings saved during re-coring of the SSC samples 

were air-dried and then physically disaggregated 

using a rubber-tipped pestle and ceramic mortar. 

Munsell (1994) colors were assigned to the dry 

bulk samples after disaggregation. A Gilson1 16-

part rotary sample divider was used to accurately 

create small representative subsamples for use in 

an optical analyzer (Coulter1 LS 230 Series). The 

optical analyzer can measure particle sizes ranging from 4×10-5 to 2 mm. Because the samples 

contained no particles greater than 2 mm, sieving 

was not required prior to splitting. The presence of 

basalt fragments usually occurred near the interface of the sediment with a basalt layer. Because 

these were not depositional clasts, basalt fragments were not considered part of a sample’s particle-size distribution. 

The Coulter1 LS 230 is a commercially available device that uses a laser to scatter light through 

a sample suspended in filtered tap water (Gee and 

Or, 2002). As the sample is circulated through a 

transparent cell, the diffraction pattern from the 

laser is measured by a series of detectors. A mathematical algorithm (Fraunhofer diffraction model) 

is used to convert the diffraction pattern into particle sizes, assuming spherically shaped particles. 

On a logarithmic scale, the bin size or ∆d interval 

is defined as log(dupper) - log(dlower), or log(dupper/

dlower), where dupper represents the upper bin limit 

and dlower represents the lower bin limit in terms 

of particle diameter. By default, the device determines the frequency of particles falling within 116 

bins, with an average ∆d of 0.041.

Subsamples on the order of 0.5–1 g were created by re-riffling a 1/16th split of the original airdried core trimmings, with the final amount 

required for analysis depending on texture. Sonication during loading of the samples and before each 

analysis was used to further disperse aggregates. 

The particle-size distribution was measured at 

least three times on a given subsample, with the 

average of the best three sequential runs used as 

the final particle-size distribution of the sample. 

The method of moments (Beyer, 1991) was 

used to calculate the geometric mean particle 

diameter and standard deviation from each of the 

measured particle-size distributions. The geometric mean particle diameter (Mg) was calculated by:

where dc is the geometric center of each bin (equal 

to ∆d/2), and f(dc) corresponds to the frequency of 

sizes occurring within each ∆d assigned to dc. The 

geometric particle-size standard deviation (σg) was 

calculated by:

( )

∑[ ] ( ) ( )

∑ ( ) = -----------------------------------------

[ ] ( ) σ

( )[ ] ( ) – ( )

⎩ ⎭ ⎨ ⎬ ⎧ ⎫

∑

∑ ( ) = ----------------------------------------------------------------------------
12

Specific Surface Area

Calculations of specific surface area are based 

on the Brunauer-Emmett-Teller (BET; 1938) theory of nitrogen gas adsorption onto a solid surface. BET theory accounts for multimolecular 

adsorption of a gas onto a solid, and the subsequent interaction between layers, whereas Langmuir theory assumes a single monolayer and 

inelastic collision of a gas molecule with the solid 

surface (Webb and Orr, 1997). Specific surface 

area is calculated from an adsorption isotherm, 

defined as the volume of gas adsorbed under various partial pressures onto a solid surface at a constant temperature. The temperature is kept fixed by 

allowing the sample to come into equilibrium with 

a bath of liquid nitrogen at 77.35 K at each partial 

pressure. The BET formula equates the rate of 

condensation of gas molecules onto an already 

adsorbed layer to the rate of evaporation from that 

layer, summed over an infinite number of layers. 

Rearranging the BET formula into a linear form 

yields:

where Va is the amount of gas adsorbed at pressure P, Vm is the amount of gas adsorbed when the 

entire solid surface is covered by a monolayer of 

the gas molecule, Po is the saturation pressure of 

the gas, and C is a constant. Measurements in the 

BET range of the adsorption isotherm (at very low 

partial pressures) should follow a linear relationship. Regressing measurements of P/(Va(P-Po)) 

against P/Po yields values of the slope and intercept terms from which C and Vm are calculated. 

The specific surface area, in m2

/g, is determined 

by:

where σ is the mean area occupied per molecule in 

the monolayer (assumed to be 16.2×10-20 m2 for 

nitrogen), NA is Avogadro's number (6.023×1023

molecules/mole), Vo is the molecular volume of 

the gas being adsorbed (22,414 cm3 at standard 

temperature and pressure for nitrogen), and m is 

the sample weight (g) (Webb and Orr, 1997).

Specific surface areas were measured for 1–2 g, 

representative splits of the core trimmings using a 

Micromeritics1

 TriStar 3000 analyzer. Samples 

were heated to 105 0C for at least 24 hours prior to 

analysis in order to evaporate water from the particle surfaces and from within pores, which can lead 

to errors in the computed values. An additional 2–

7 hours of degassing by nitrogen while heating at 

105 0

C occurred prior to analysis. Five points on 

the adsorption isotherm were measured to calculate specific surface areas. The sample weight was 

taken as the weight prior to analysis (after ovendrying and nitrogen degassing). 

RESULTS AND DISCUSSION

This study provides information on the hydraulic and bulk properties of sedimentary interbeds at 

the VZRP located near the INTEC. The measurement of texture and hydraulic properties at multiple borehole locations and depths is important for 

understanding the spatial distribution of sedimentary interbed properties, developing flow and 

transport models, and comparing field and laboratory hydraulic measurements. Because measurement of unsaturated hydraulic properties is often 

time and labor intensive, detailed particle-size data 

are useful for applying similar-media scaling 

(Miller and Miller, 1956; Miller, 1980; Nimmo 

and others, 2002a) to existing hydraulic properties 

or predicting hydraulic properties using available 

transfer functions (Arya and Paris, 1981; Schaap, 

1999). Particle-size information is also useful for 

interpreting depositional environments within the 

interbeds. This report describes the spatial variability of the measured hydraulic and bulk properties of the interbeds beneath the VZRP, as reported 

in this study and that of Perkins (2003).

Laboratory Measurements

Saturated hydraulic conductivity (Ksat), saturated water content (θsat), and the unsaturated 

hydraulic relations (K(θ) and θ(ψ)) were measured on 10 core samples from six boreholes (fig. 

3). Particle size, bulk density, particle density, 

porosity, and specific surface area were measured 

( ) – -------------------------- ---------- – ----------- ----- ⎝ ⎠ ⎛ ⎞ = +

σ

= ------------------
13

on material from the same depths as the SSC core 

samples. These measurements were made on trimmings saved during sample re-coring. An additional 66 particle-size distributions were measured 

on bulk samples, with sample intervals ranging in 

thickness from 6.4 to 25.4 mm, from each of the 

original 0.3- to 0.6-m-long core sections (on average, 13 measurements per meter of core). Fewer 

bulk particle-size distributions were measured on 

core sections containing obviously disturbed material or solid basalt intervals.

Particle density values are reported in table 1 

along with the initial bulk density and porosity 

values (ρbi and Φi

), determined prior to measurement of unsaturated hydraulic properties in the 

centrifuge, and the final values (ρbf and Φf

), which 

were determined after all centrifuge measurements were completed. Compaction as a result of 

the disturbed state of the samples was observed in 

most cases as evidenced by an increase in bulk 

density between the initial and final values.

Values of Ksat and θsat are listed in table 2 for 

each core sample, including the method used to 

determine Ksat. θsat values were calculated using 

the initial bulk density (ρbi) of the sample (table 1) 

determined after measurement of Ksat. Saturated 

hydraulic conductivities ranged from 2.07×10-7 to 

8.31×10-4 cm/s, which are typical for samples of 

silt loam texture. The core sample from ICPP-SCIV-189 at 36.59 to 36.69 m had a high value of 

Ksat, 8.31×10-4cm/s, compared to the other samples, likely due to macropores within the sample or 

disturbance caused by handling or drilling. 

The measured sets of K, θ, and ψ for each of 

the 10 core samples are listed in table 3. The first 

values listed for each sample are θsat and Ksat. The 

method used to measure ψ at each θ is indicated in 

a separate column, except for θsat where a value of 

-0.1 cm-water was assumed. Water retention 

curves (θ(ψ)) are shown in figure 4, with measurements indicated by symbols. Curves shown as dotted lines were fit to the measurements using the 

van Genuchten (1980) function. An average of 

eight matric pressure values was measured per 

sample, with measurements sometimes extending 

beyond the range of θ achieved by the SSC 

method. Measurements of hydraulic conductivity 

as a function of water content (K(θ)) are shown in 

figure 5. The number of unsaturated K values measured per sample varied depending on texture. 

Fine-textured samples had fewer points because 

their lower Ksat values meant a smaller range of 

unsaturated K fell within the measurable range of 

the SSC method. Because compaction usually 

occurred after the first unsaturated K measurement and sample recesses were not measured until 

after the final K measurement, unsaturated water 

contents were calculated using the final bulk density (ρbf) of the sample (table 1). 

Cumulative particle-size distributions on a percent-finer-than basis are shown in figure 6 for each 

core sample. Table 4 lists the textural class percentages and textural names for each bulk and core 

sample based on the U.S. Department of Agriculture’s soil classification system (Soil Survey Staff, 

1975). Sample textures ranged from silty clay 

loam, with a maximum clay content of 29 percent, 

to loam, with a minimum clay content of 7 percent. However, most samples were classified as 

silt loams. Specific surface areas for each of the 10 

SSC samples are given in table 5.

The unsaturated hydraulic properties for two 

samples taken from vertically adjacent locations in 

borehole ICPP-SCI-V-214 at depths of 43.85 m 

and 43.96 m showed conflicting results. Because 

these samples have closely matched particle-size 

distributions (fig. 6), their unsaturated hydraulic 

properties should also agree. The results for the 

sample at 43.96 to 44.05 m depth are suspect 

because a gap, likely caused by an error in the recoring process, was discovered at the bottom of 

the sample retainer after all K, θ, and ψ measurements were completed. This made it difficult to 

determine the sample length used in calculating 

Ksat, bulk density, porosity, and θsat. The effect of 

this disturbance is also evident in the K(θ) and 

θ(ψ) relations (figs. 4 and 5), where θ is shifted 

toward lower values, as if the sample texture was 

coarser than measured.

35-m, 45-m, and 55-m Interbeds

Three relatively thick interbeds were identified 

from drilling logs (Bechtel BWXT Idaho, LLC, 

2002; USGS visual log for ICPP-SCI-V-215, 

Linda Davis, USGS, personal commun., 2003) of 

the 32 boreholes located within the VZRP at 
14

Figure 4. Water content as a function of matric pressure, measured using the steady-state centrifuge method, for 10 se

interbed core samples collected from depths of 36.59 to 56.33 m below land surface within the Vadose Zone 

Idaho National Engineering and Environmental Laboratory, Idaho. Symbols represent measured points and represent optimized curves fitted with the van Genuchten (1980) formula.

1000000 100000 10000 1000 100 10 1 

MATRIC PRESSURE, IN CENTIMETERS OF WATER

 ICPP-SCI-V-189 36.59 m - 36.69 m ICPP-SCI-V-198 42.91 m - 43.00 m ICPP-SCI-V-204 48.41 m - 48.49 m ICPP-SCI-V-205 42.30 m - 42.54 m ICPP-SCI-V-213 37.91 m - 38.00 m ICPP-SCI-V-213 56.08 m - 56.15 m ICPP-SCI-V-214 39.40 m - 39.50 m ICPP-SCI-V-214 43.85 m - 43.96 m ICPP-SCI-V-214 43.96 m - 44.05 m ICPP-SCI-V-214 56.24 m - 56.33 m

-1000000 -100000 -10000 -1000 -100 -10 -1 

Borehole

Depth belowland surface
15

Figure 5. Hydraulic conductivity as a function of water content, measured using the steady-state centrifuge method, for 

interbed core samples collected from depths of 36.59 to 56.33 m below land surface within the Vadose Zone R

Idaho National Engineering and Environmental Laboratory, Idaho.

1.E-101.E-091.E-081.E-071.E-061.E-051.E-041.E-03

0 0.1 0.2 0.3 0.4 0.5 

VOLUMETRIC WATER CONTENT

HYDRUAULIC CONDUCTIVITY,

IN CENTIMETERS PER SECOND

 ICPP-SCI-V-189 36.59 m - 36.69 m ICPP-SCI-V-198 42.91 m - 43.00 m ICPP-SCI-V-204 48.41 m - 48.49 m ICPP-SCI-V-205 42.30 m - 42.54 m ICPP-SCI-V-213 37.91 m - 38.00 m ICPP-SCI-V-213 56.08 m - 56.15 m ICPP-SCI-V-214 39.40 m - 39.50 m ICPP-SCI-V-214 43.85 m - 43.96 m ICPP-SCI-V-214 43.96 m - 44.05 m ICPP-SCI-V-214 56.24 m - 56.33 m

10-310-810-710-6 10-510-4 10-9

10-10

Borehole

Depth belowland surface
16

Figure 6. Cumulative particle-size distributions on a percent-finer-than basis for 10 sedimentary interbed core samples co

36.59 to 56.33 m below land surface within the Vadose Zone Research Park, Idaho National Engineering and En

Laboratory, Idaho.

0

102030405060708090

100

0.0001 0.001 0.01 0.1 

PARTICLE DIAMETER, IN MILLIMETERS

PERCENTAGE OF PARTICLES

FINER THAN INDICATED SIZE ICPP-SCI-V-189 36.59 m - 3

 ICPP-SCI-V-198 42.91 m - 4

 ICPP-SCI-V-204 48.41 m - 4

 ICPP-SCI-V-205 42.30 m - 4

 ICPP-SCI-V-213 37.91 m - 3

 ICPP-SCI-V-213 56.08 m - 5

 ICPP-SCI-V-214 39.40 m - 3

 ICPP-SCI-V-214 43.85 m - 4

 ICPP-SCI-V-214 43.96 m - 4

 ICPP-SCI-V-214 56.24 m - 5

Borehole

Depth belowland surfac
17

depths of approximately 35, 45, and 55 m below 

land surface. The 35-m interbed ranges in thickness from 0.6 to 8.5 m and is present in all of the 

25 boreholes drilled to this depth or deeper. The 

45-m interbed ranges from 0.6 to 10 m in thickness and is present in 6 (ICPP-SCI-V-189, -201A, 

-204, -205, -215, and ICPP-MON-V-212) of the 

18 boreholes drilled to this depth or greater. The 

depth range for the 35- and 45-m interbeds tends 

to overlap due to local variations in the underlying 

basalt topography. The 55-m interbed ranges in 

thickness from 0.3 to 5 m and is encountered in 9 

(ICPP-MON-A-165, -166, -167, ICPP-SCI-V-201, 

-209, ICPP-MON-V-212, ICPP-SCI-V-213, -214, 

and -215) of the 10 boreholes drilled to this depth 

or deeper. Thinner interbeds, ranging in thickness 

from 0.15 to 4.57 m, were noted in several of the 

holes from the drilling logs (Bechtel BWXT 

Idaho, LLC, 2002). 

The 35-m interbed is laterally extensive to at 

least 900 m within the VZRP between the Big Lost 

River and the new percolation pond area. Because 

most boreholes were drilled to 50 m or less, it is 

difficult to make inferences about the lateral continuity of the 45- and 55-m interbeds. 

Spatial variation of interbed properties

The geometric mean particle size and standard 

deviation for each of the 90 samples from this 

study and that of Perkins (2003) are plotted with 

adjusted depth in figures 7 and 8. Due to local 

variations in the topography of the underlying 

basalt flows and interbed thickness, the depths 

associated with each interbed vary slightly from 

hole to hole. In order to compare interbed properties between boreholes on an equal basis, the sample depths have been corrected to the tops of the 

interbed in a given hole. This was accomplished 

by subtracting the sample depth from the depth 

associated with the top of the interbed in each 

borehole (from the lithologic logs). Each of these 

numbers was then subtracted from the average 

starting depth of the respective interbed, defined at 

35, 45, and 55 m. This approach effectively 

“straightens” the interbed highs and lows so that 

the top of each interbed lies on a horizontal plane. 

The bottom depth of each interbed varies depending on local interbed thicknesses. Each symbol 

represents the distance of a sample borehole from 

ICPP-SCI-V-189 along cross section A-A' (shown 

in figure 3).

The textural variability within each interbed 

can be examined using figures 7 and 8. Vertically, 

the 35-m interbed is fairly uniform in geometric 

mean particle diameter and standard deviation, 

with the exception of samples from ICPP-SCI-V214, which show more variation. The geometric 

mean particle diameter ranges from 0.0034 to 

0.0160 mm, with the geometric standard deviation 

ranging from 2.8 to 4.6, indicating a moderately 

well-sorted material. Laterally, the particle-size 

statistics of the 35-m interbed vary little between 

boreholes at comparable sample depths. The 45-m 

interbed shows a coarsening upward trend, with 

the greatest spread in particle sizes near the top of 

the interbed. The geometric mean particle diameter ranges from 0.0038 to 0.1715 mm and the standard deviation varies from 2.8 to 8.3, increasing 

upward. The material from ICPP-SCI-V-215 is 

coarser and has a greater spread in particle sizes 

than that of ICPP-SCI-V-204, located approximately 240 m to the northwest. The 55-m interbed 

displays more variation in particle size vertically, 

with the mean ranging from 0.0081 to 0.1992 mm 

and the standard deviation ranging from 2.7 to 9.4. 

The sediment from ICPP-SCI-V-213 and ICPPSCI-V-214 span similar ranges of mean particle 

size, while the sediment from ICPP-SCI-V-215 is 

coarser. Lateral heterogeneity within the 45- and 

55-m interbeds is difficult to discern because few 

boreholes within the VZRP were drilled to these 

depths.

Textural differences between the 35-m, 45-m, 

and 55-m interbeds can be compared from the histograms presented in Figure 9, where the distributions of geometric mean particle diameter and 

standard deviation are plotted based on the number of samples analyzed per interbed. The 35-m 

interbed contains the finest material, with most of 

the samples plotting near the geometric mean particle diameter of 0.0042 mm. The 55-m interbed 

contains the coarsest material (up to 0.237 mm), 

with the largest frequency of samples having values near 0.0133 mm. The distribution of means 

from the 45-m interbed overlaps that of the other 

two.
18

Figure 7. Geometric mean particle diameter for 90 samples (from this study and that of Perkins (2003)) plotted with de

surface for (a) the 35-m interbed, (b) the 45-m interbed, and (c) the 55-m interbed. Depths were adjusted to th

interbeds. Symbols represent the distances of sample boreholes (in parentheses) from ICPP-SCI-V-189 along 

A-A' shown in figure 3.

(a) 

3536373839404142434445

0.001 0.01 0.1 1

GEOMETRIC MEAN PARTICLE DIAMETER, IN MM

ADJUSTED DEPTH BELOW SURFACE, IN M ADJUSTED DEPTH BELOW SURFACE, IN METERS 

GEOMETRIC MEAN PARTICLE 

DIAMETER, IN MILLIMETERS 

(b) 

4546474849505152535455

0.001 0.01 0.1 1

GEOMETRIC MEAN PARTICLE DIAMETER, IN MM

ADJUSTED DEPTH BELOW SURFACE, IN M 0 m (ICPP-SCI-V-189) 42 m (ICPP-SCI-V-213) 478 m (ICPP-SCI-V-214)

 683 m (ICPP-SCI-V-198) 781 m (ICPP-SCI-V-205) 863 m (ICPP-SCI-V-204) 1103 m (ICPP-SCI-V-215)

ADJUSTED DEPTH BELOW SURFACE, IN METERS 

GEOMETRIC MEAN PARTICLE 

DIAMETER, IN MILLIMETERS 

5556575859606162636465

0.001 0.01 

GEOMETRIC MEAN 

ADJUSTED DEPTH BELOW SURFACE, IN M ADJUSTED DEPTH BELOW SURFACE, IN METERS 

GEOMETRIC 

DIAMETER

(c) 
19

Figure 8. Geometric particle-size standard deviation for 90 samples (from this study and that of Perkins (2003)) plotted w

surface for (a) the 35-m interbed, (b) the 45-m interbed, and (c) the 55-m interbed. Depths were adjusted to the 

Symbols represent distances of sample boreholes (in parentheses) from ICPP-SCI-V-189 along cross section A-

(a) 

3536373839404142434445

0 2 4 6 8 10

GEOMETRIC STANDARD DEVIATION

ADJUSTED DEPTH BELOW SURFACE, IN M

ADJUSTED DEPTH BELOW SURFACE, IN METERS 

(b) 

4546474849505152535455

0 2 4 6 8 10

GEOMETRIC STANDARD DEVIATION

ADJUSTED DEPTH BELOW SURFACE, IN M 0 m (ICPP-SCI-V-189) 42 m (ICPP-SCI-V-213) 478 m (ICPP-SCI-V-214) 683 m (ICPP-SCI-V-198)

 781 m (ICPP-SCI-V-205) 863 m (ICPP-SCI-V-204) 1103 m (ICPP-SCI-V-215)

ADJUSTED DEPTH BELOW SURFACE, IN METERS 

(c) 

5556575859606162636465

0 2 4 

GEOMETRIC S

ADJUSTED DEPTH BELOW SURFACE, IN M

ADJUSTED DEPTH BELOW SURFACE, IN METERS 
20

Figure 9. Frequency distribution of 90 samples (from this study and that of Perkins (2003)) within the 

35-m, 45-m, and 55-m interbeds, based on (a) geometric mean particle diameter and (b) 

geometric standard deviation.

(a) 

0

10

20

30

40

50

60

70

0.001 0.01 0.1 1

GEOMETRIC MEAN PARTICLE DIAMETER, IN MILLIMETERS

FREQUENCY OF SAMPLES PER INTERBED

35-m interbed

45-m interbed

55-m interbed

(b) 

0

10

20

30

40

50

2 3 4 5 6 7 8 9 10

GEOMETRIC STANDARD DEVIATION

FREQUENCY OF SAMPLES PER INTERBED

35 m-interbed

45-m interbed

55-m interbed
21

Over the 1,100-m distance along the cross-section line A-A' (fig. 3), the geometric mean particle 

diameter and standard deviation vary little at the 

top and base of the 35-m interbed. The predominantly silt loam texture of this interbed and the relatively small values of geometric particle-size 

standard deviation suggest a low-energy depositional environment, possibly of floodplain or 

lacustrine origin. The 45-m interbed coarsens 

upward both locally (within ICPP-SCI-V-215) and 

over a distance of 200 m (between ICPP-SCI-V204 and ICPP-SCI-V-215). Hughes (1993) interpreted coarsening upward sequences as being 

deposited by low-energy fluvial systems followed 

by higher energy fluvial systems, although the 

coarse layer here is comprised of sandy loam, not 

sand or gravel. The 55-m interbed shows the most 

textural variability, with no clear trend such as 

upward fining or coarsening. This may indicate 

more prominent depositional layering within this 

interbed, possibly from a braided fluvial environment. Bartholomay (1990) showed that the mineralogy of interbed sediments in the vicinity of the 

INTEC is similar to that of the modern Big Lost 

River deposits. Source areas and drainage patterns 

during interbed deposition may have been similar 

to those of the present day, suggesting that the siltrich interbeds under the INTEC may be floodplain 

deposits of a river containing sediment similar to 

modern Big Lost River deposits.

Differences in particle size between the interbeds suggest that the hydraulic behavior of these 

interbeds will be different. Small-scale heterogeneity (less than a few meters) in the interbeds 

could enhance lateral flow or inhibit downward 

vertical flow depending on field water contents. 

Figure 10 shows saturated hydraulic conductivity, 

measured for the 22 core samples reported in this 

study and that of Perkins (2003), plotted with 

adjusted depth for each of the three interbeds. The 

Ksat values follow the same general trends as the 

particle size data. The 35-m interbed has Ksat values in the low to middle range of the spectrum 

with the exception of one sample with an anomalously high value of 8.31×10-4 cm/s. For the 45-m 

interbed, Ksat decreases with depth, consistent 

with the downward fining of particle size. For the 

55-m interbed, Ksat generally increases with depth. 

This is consistent with the observed increase in the 

geometric mean particle size with depth. At low 

water contents, the presence of coarser sediment at 

the base of the 55-m interbed may promote lateral 

flow in the overlying fine interval. At higher water 

contents, this coarse-textured interval may act as a 

conduit for lateral flow along the underlying 

impermeable basalt interface or until fractures in 

the basalt are encountered. One implication of 

reduced permeability with depth is the possibility 

of water accumulating above a fine layer. The sedimentary intervals with the lowest Ksat values (10-7

cm/s) may cause the formation of perched water 

zones within or above the 35-, 45-, or 55-m interbeds.

Baked-zone intervals

Baked-zone intervals were identified qualitatively by their oxidized color and by their proximity to the tops of the interbeds. The oxidized color 

of the tops of the interbeds could be due to various factors, including the presence of organic 

material, the amount and type of iron, and whether 

water has leached iron out of the oxidized interval 

after basalt deposition. Most of the intervals 

defined as “baked” had basalt clasts present in the 

sediment or the actual basalt-sediment interface 

was observed through the transparent core liner. 

The fact that a distinct sediment color change 

occurs near the basalt interface seems to indicate 

that the intervals are baked, with the color likely 

varying because of other factors such as iron 

leaching, the form of iron in the original sediment 

(whether amorphous or not), and the amount of 

soil development. Also, the extent of baked-zone 

alteration depends on the temperature of the 

magma and the water content of the sediment during basalt deposition (Cecil and others, 1991).

After categorizing the material analyzed for 

particle size into initial color groups, each group 

was assigned a Munsell (1994) color (table 6). For 

hole ICPP-SCI-V-189, the top of a baked zone was 

identified from 36.59 to 37.04 m based on the reddish-yellow color (7.5YR 6/6). This 0.45-m interval represents a minimum thickness because 

material below 37.04 m was not analyzed. For 

hole ICPP-SCI-V-213, material from 37.50 to 

38.11 m was also classified as reddish yellow 

(7.5YR 6/6). Material immediately above 37.50 m 
22

Figure 10. Saturated hydraulic conductivity for 22 core samples (from this study and that of Perkins (2003)) plotted with 

surface for (a) the 35-m interbed, (b) the 45-m interbed, and (c) the 55-m interbed. Depths were adjusted to the 

Symbols represent the distance of the sample boreholes (in parentheses) from ICPP-SCI-V-189 along cross secfigure 3.

3536373839404142434445

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02

SATURATED HYDRAULIC CONDUCTIVITY, IN CM/S

ADJUSTED DEPTH BELOW SURFACE, IN M

(a) 

10-7 10-6 10-4 10-3 10-5 10-2

ADJUSTED DEPTH BELOW SURFACE, IN METERS 

SATURATED HYDRAULIC CONDUCTIVITY, 

IN CENTIMETERS PER SECOND 

4546474849505152535455

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02

SATURATED HYDRAULIC CONDUCTIVITY, IN CM/S

ADJUSTED DEPTH BELOW SURFACE, IN M 0 m (ICPP-SCI-V-189) 42 m (ICPP-SCI-V-213) 478 m (ICPP-SCI-V-214) 683 m (ICPP-SCI-V-198)

 781 m (ICPP-SCI-V-205) 863 m (ICPP-SCI-V-204) 1103 m (ICPP-SCI-V-215)

(b) 

10-7 10-6 10-4 10-3 10-5 10-2

ADJUSTED DEPTH BELOW SURFACE, IN METERS 

SATURATED HYDRAULIC CONDUCTIVITY, 

IN CENTIMETERS PER SECOND 

5556575859606162636465

1.E-07 1.E-06 1.E-

SATURATED HYDRAU

ADJUSTED DEPTH BELOW SURFACE, IN M

(c) 

10-7 10-6 

10

ADJUSTED DEPTH BELOW SURFACE, IN METERS 

SATURATED HY

IN CENTIME
23

was not recovered during drilling and material 

from 38.11 m to the base of the interbed at 

42.07 m was not analyzed. The minimum bakedzone thickness is 0.61 m in this borehole for the 

35-m interbed. For hole ICPP-SCI-V-214, a baked 

interval of yellowish-red color (5YR 5/6 to 5YR 5/

8) exists from 55.94 to 56.03 m. Immediately 

below this interval, from 56.03 to 56.40 m, the 

material is light brown (7.5YR 6/4). It is likely that 

the baked zone extends from the top of the interbed at 55.79 to 56.03 m (with a maximum thickness equal to 0.24 m).

Baked sediment was not present at the top of 

every interbed studied. In hole ICPP-SCI-V-213, 

material from 55.79 to 56.14 m was light yellowish brown (10YR 6/4) to light brown (7.5YR 6/4). 

The top of the interbed occurs at 55.09 m according to the lithologic log (Bechtel BWXT Idaho, 

LLC, 2002), so there is potentially 0.7 m of baked 

material overlying the interval studied. In hole 

ICPP-SCI-V-214, the material analyzed from the 

top of the interbed at 39.26 m to a depth of 

39.63 m is very pale brown (10YR 7/3). Lower in 

the same interbed, from 43.75 to 44.36 m, the sediment is also very pale brown.

Baked-zone material was studied for the 45- 

and 55-m interbeds in borehole ICPP-SCI-V-215 

by Perkins (2003). Munsell (1994) colors for this 

borehole were not described by Perkins (2003), 

but are assigned here. The material in the 45-m 

interbed grades from reddish yellow (7.5YR 6/6) 

to light brown (7.5YR 6/4) with increasing depth, 

with the baked interval occurring from 45.53 to 

45.95 m. The top of the interbed occurs at 45.24 m 

according to the visual lithologic log (Linda Davis, 

USGS, personal commun., 2003), making the 

maximum thickness of this baked interval 0.71 m. 

The material in the 55-m interbed changes from 

red (2.5YR 5/6) to brown (7.5YR 5/4) with 

increasing depth. The baked interval occurs from 

58.36 to 59.30 m, based on the material studied. 

The maximum thickness, with the top of the interbed starting at 57.29 m in the visual lithologic log, 

is 2.01 m. 

Table 6 compares the average particle-size statistics (geometric mean and standard deviation) for 

baked and non-baked intervals based on the number of samples indicated in the last column. In 

general, there is no distinct particle-size difference between baked-zone material and the underlying non-baked sediment. There is lateral 

variation in particle size between baked intervals. 

The baked zone of the 55-m interbed of ICPP-SCIV-215 is coarser than the baked zone for the same 

interbed in ICPP-SCI-V-214, and the baked zone 

of the 35-m interbed in ICPP-SCI-V-189 is coarser 

than that for the same interbed in ICPP-SCI-V213. The average geometric particle-size standard 

deviation ranges from 2.95 to 5.79 for non-baked 

sediment and ranges from 3.34 to 7.82 for baked 

sediment for all interbeds and boreholes, with the 

largest standard deviations occurring in the 45-m 

interbed of ICPP-SCI-V-215.

Figure 11 compares θ(ψ) and K(θ) curves measured on cores from baked-zone intervals identified in ICPP-SCI-V-189 and ICPP-SCI-V-213 

(from this study) and from ICPP-SCI-V-215 (Perkins, 2003). Strong aggregation due to clay coatings on particles was observed within the baked 

zone of the 45-m interbed of ICPP-SCI-V-215 

(Perkins, 2003); no aggregation was observed in 

the baked-zone intervals of the 35- or 55-m interbeds. Any structural influences on the hydraulic 

properties due to aggregation are subtle compared 

to the textural influences. The cores group by texture with the coarsest samples occurring in the 

baked zone of the 55-m interbed of ICPP-SCI-V215 and the finest samples in the baked zones of 

the 35-m interbed in holes ICPP-SCI-V-189 and 

ICPP-SCI-V-213.

SUMMARY

Three relatively thick interbeds, starting at 

depths of approximately 35, 45, and 55 m below 

land surface, were identified from 32 boreholes 

drilled within the VZRP. The 35-m interbed is laterally extensive to at least 900 m within the VZRP 

between the Big Lost River and the new percolation pond area for the INTEC facility. Not enough 

information was available, due to limited borehole 

completion depths, to infer the lateral extent of the 

45- and 55-m interbeds. The majority of the samples analyzed in this study were classified as silt 

loams. The 35-m interbed contained the finest 

samples, with an average geometric mean particle 

size of 0.0063 mm based on 54 samples, while the 
24

Figure 11. Comparison of unsaturated hydraulic properties measured on core samples (from this study 

and that of Perkins (2003)) from baked-zone intervals defined in the 35-m (red symbols), 

45-m (green), and 55-m (blue) interbeds. (a) Water content as a function of matric pressure, 

or water retention. (b) Hydraulic conductivity as a function of water content.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

1000000 100000 10000 1000 100 10 1 0.1

MATRIC PRESSURE, IN CENTIMETERS OF WATER

VOLUMETRIC WATER CONTENT

 ICPP-SCI-V-189 36.59 m silt loam

 ICPP-SCI-V-213 37.91 m silt loam

 ICPP-SCI-V-215 45.53 m sandy loam

 ICPP-SCI-V-215 45.59 m sandy loam

 ICPP-SCI-V- 215 45.85 m sandy loam

 ICPP-SCI-V-215 58.36 m sand

 ICPP-SCI-V-215 58.55 m loamy sand

 ICPP-SCI-V-215 59.20 m silt loam

Borehole

Depth below

land surface Texture

-1000000 -100000 -10000 -1000 -100 -10 -1 -0.1

(a) 

(b) 

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

0 0.1 0.2 0.3 0.4 0.5 0.6

VOLUMETRIC WATER CONTENT

HYDRAULIC CONDUCTIVITY,

IN CENTIMETERS PER SECOND 

 ICPP-SCI-V-189 36.59 m silt loam

 ICPP-SCI-V-213 37.91 m silt loam

 ICPP-SCI-V-215 45.85 m sandy loam

 ICPP-SCI-V-215 58.36 m sand

 ICPP-SCI-V-215 58.55 m loamy sand

 ICPP-SCI-V-215 59.20 m silt loam

10-2

10-7

10-6

10-5 

10-4

10-3 

10-8

10-10

10-9

Borehole

Depth below

land surface Texture
25

55-m interbed had the coarsest material with an 

average geometric mean particle size of 0.0494 

mm based on 18 samples. The average geometric 

mean particle size of the 45-m interbed was 0.0316 

mm, based on 18 samples. The 35-m interbed was 

the most uniform texturally, both vertically and 

laterally over the 900 m range studied. The 45-m 

interbed coarsened upward vertically, with the 

coarsest material located near the new percolation 

pond area. The 55-m interbed showed more variation in particle size with depth.

Saturated hydraulic conductivity values ranged 

from 1.66×10-7 to 1.42×10-3 cm/s for the 10 samples from this study and the 12 samples from 

ICPP-SCI-V-215 (Perkins, 2003). For six samples 

from the 35-m interbed (excluding one sample 

with an anomalously high value), the average Ksat

was 1.525×10-6 cm/s and the average porosity was 

0.4678. For the 45-m interbed, the average Ksat

was 6.67×10-5 cm/s for seven samples and the 

average porosity was 0.4963 based on nine samples. The average Ksat for the 55-m interbed was 

3.644×10-4 cm/s and the porosity was 0.5144 for 

eight samples. Low permeability intervals (with 

Ksat values of 10-7

 cm/s or less) within the 35- and 

45-m interbeds may cause perched water zones to 

form, and promote lateral flow within the overlying, more coarsely textured sediment intervals or 

rubble zones at basalt-sediment interfaces. 

Baked zones were identified at the tops of the 

(1) 35-m interbed, in holes ICPP-SCI-V-189 and 

ICPP-SCI-V-213, (2) 45-m interbed, in ICPP-SCIV-215, and (3) 55-m interbed, in holes ICPP-SCIV-214 and ICPP-SCI-V-215. The average geometric mean particle diameter for these baked intervals did not differ significantly from that of the 

underlying non-baked intervals. Available hydraulic property data, from this study and from Perkins (2003), were compared for these intervals. 

Although aggregation was observed for cores from 

the 45-m interbed in ICPP-SCI-V-215, the effect 

on the hydraulic properties was subtle when compared to textural influences. Therefore, the hydraulic properties of baked-zone intervals are not likely 

to differ significantly from non-baked intervals 

except as affected by texture.

Beneath the old percolation ponds near the 

INTEC, perched water zones were observed to 

form presumably as a result of reduced permeability layers at depth and the high inputs of water to 

the ponds. Reduced permeability zones in the 35-, 

45-, and 55-m interbeds, based on analyses presented in this study, may contribute to perching 

below the new percolation pond area. If large 

inputs of water are applied to the ponds or large 

amounts of water from the nearby Big Lost River 

infiltrate the subsurface, mounding of perched 

water can contribute to lateral flow—a potential 

mechanism for contaminant transport away from 

the new percolation ponds.

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28

Table 1. Measured values of bulk density, particle density, and porosity for 10 core samples

[Initial bulk density (ρbi ) and porosity (Φi) values represent the state of the samples after re-coring them for the steadystate centrifuge method, prior to centrifugation. Final values (ρbf and Φf

) were calculated after the completion of all 

centrifuge and matric pressure measurements. Particle density (ρs) was measured on excess material saved during 

sample re-coring.]

Table 2. Saturated hydraulic conductivity determined by the falling-head method and the associated saturated 

water content for 10 core samples

[For some samples, an alternative version of the standard falling-head method, using a centrifuge, was implemented to 

measure saturated hydraulic conductivity (Ksat). Abbreviations: S = the standard application (gravity driven only); C = 

a centrifuge was used to increase the driving force for flow (in addition to gravity).]

Borehole

Depth

interval

(m)

Particle

density, ρs

(g/cm3)

Initial bulk

density, ρbi

(g/cm3)

Final bulk

density, ρbf

(g/cm3)

Initial total

porosity, Φi

(cm3/cm3)

Final total

porosity, Φf

(cm3/cm3)

ICPP-SCI-V-189 36.59–36.69 2.74 1.18 1.19 0.5705 0.5661

ICPP-SCI-V-198 42.91–43.00 2.80 1.41 1.53 0.4972 0.4553

ICPP-SCI-V-204 48.41–48.49 2.84 1.35 1.39 0.5244 0.5096

ICPP-SCI-V-205 42.30–42.54 2.80 1.44 1.50 0.4872 0.4642

ICPP-SCI-V-213 37.91–38.00 2.77 1.38 1.54 0.5028 0.4444

ICPP-SCI-V-213 56.08–56.15 2.80 1.25 1.40 0.5528 0.5014

ICPP-SCI-V-214 39.40–39.50 2.74 1.49 1.60 0.4575 0.4156

ICPP-SCI-V-214 43.85–43.96 2.78 1.51 1.53 0.4562 0.4499

ICPP-SCI-V-214 43.96–44.05 2.74 1.63 1.63 0.4061 0.4061

ICPP-SCI-V-214 56.24–56.33 2.82 1.48 1.71 0.4755 0.3944

Borehole

Depth interval

(m)

Saturated hydraulic 

conductivity, Ksat

(cm/s) Method

Saturated 

water content, θsat

(cm3/cm3)

ICPP-SCI-V-189 36.59–36.69 8.31×10-4 S 0.5661

ICPP-SCI-V-198 42.91–43.00 6.35×10-7 S 0.4904

ICPP-SCI-V-204 48.41–48.49 4.80×10-6 S 0.5134

ICPP-SCI-V-205 42.30–42.54 2.07×10-7 C 0.4752

ICPP-SCI-V-213 37.91–38.00 3.99×10-6 C 0.4829

ICPP-SCI-V-213 56.08–56.15 1.44×10-5 S 0.5368

ICPP-SCI-V-214 39.40–39.50 3.34×10-6 C 0.4591

ICPP-SCI-V-214 43.85–43.96 5.20×10-7 C 0.4593

ICPP-SCI-V-214 43.96–44.05 4.59×10-7 C 0.3585

ICPP-SCI-V-214 56.24–56.33 2.81×10-5 S 0.4546
29

Table 3. Unsaturated hydraulic property measurements for 10 core samples

[The first values listed for each sample are the saturated values of water content (θ) and hydraulic conductivity (K), 

assuming the matric pressure (ψ) is -0.1 cm-water. Saturated water contents were determined using initial volumes 

calculated prior to centrifugation; subsequently drier water contents were calculated using the final sample volume 

determined after centrifugation. A tensiometer was generally used for the pressure range > -700 cm-water; the filter 

paper method was used for the range < -700 cm-water. Abbreviations: T = tensiometer; F = filter paper method; ND = 

not determined; A = assumed.] 

Borehole

Depth interval 

(m)

Matric pressure, 

ψ (cm-water) Method

Water content, θ 

(cm3/cm3)

Hydraulic 

conductivity, K

(cm/s)

ICPP-SCI-V-189 36.59–36.69 -0.10 A 0.5661 8.31×10-4

ND 0.4869 1.66×10-5

-103.36 T 0.4509 2.49×10-6

-150.83 T 0.4389 1.24×10-6

-254.66 T 0.4239 4.15×10-7

-450.17 T 0.4051 8.29×10-8

-646.77 T 0.3877 3.14×10-8

ND 0.3590 5.31×10-9

-989.83 F 0.3442 5.84×10-10

-4,206.87 F 0.2916 ND

-40,418.04 F 0.2112 ND

-144,436.53 F 0.1610 ND

ICPP-SCI-V-198 42.91–43.00 -0.10 A 0.4904 6.35×10-7

-283.84 T 0.4810 8.33×10-8

-429.60 T 0.4635 4.17×10-8

-1,471.36 F 0.4388 6.30×10-9

-1,567.72 F 0.4343 5.87×10-10

-4,998.58 F 0.3936 ND

-7,474.01 F 0.3549 ND

-25,827.87 F 0.2430 ND

ICPP-SCI-V-204 48.41–48.49 -0.10 A 0.5134 4.80×10-6

-182.47 T 0.4839 4.08×10-7

ND 0.4651 8.16×10-8

-731.63 F 0.4506 3.09×10-8

-1,362.38 F 0.4419 5.22×10-9

-1,575.27 F 0.4390 9.93×10-10
Table 3. Unsaturated hydraulic property measurements for 10 core samples—Continued

30

ICPP-SCI-V-204 48.41–48.49 -4,087.46 F 0.3767 ND

-5,477.04 F 0.3291 ND

-30,020.44 F 0.2259 ND

ICPP-SCI-V-205 42.30–42.54 -0.10 A 0.4752 2.07×10-7

-749.46 F 0.4457 3.09×10-8

-1,700.01 F 0.4344 5.22×10-9

-2,372.78 F 0.4300 9.93×10-10

-5,866.91 F 0.3658 ND

-8,648.10 F 0.3063 ND

-40,517.24 F 0.2192 ND

ICPP-SCI-V-213 37.91–38.00 -0.10 A 0.4829 3.99×10-6

-440.15 T 0.4643 4.13×10-7

-605.01 F 0.4459 8.26×10-8

-846.96 F 0.4227 3.12×10-8

-1,467.96 F 0.4136 5.28×10-9

-1,857.58 F 0.4067 1.00×10-9

-2,876.28 F 0.3584 ND

-4,107.16 F 0.3179 ND

-10,973.00 F 0.2131 ND

ICPP-SCI-V-213 56.08–56.15 -0.10 A 0.5368 1.44×10-5

-279.29 T 0.4801 4.14×10-7

-587.02 T 0.4581 8.28×10-8

-770.85 T 0.4317 3.13×10-8

ND 0.4066 5.30×10-9

-1,295.02 F 0.3979 5.83×10-10

-2,678.79 F 0.3567 ND

-7,536.91 F 0.2565 ND

-109,289.94 F 0.1551 ND

ICPP-SCI-V-214 39.40–39.50 -0.10 A 0.4591 3.34×10-6

-587.06 T 0.4389 4.10×10-7

-584.82 F 0.4229 8.20×10-8

Borehole

Depth interval 

(m)

Matric pressure, 

ψ (cm-water) Method

Water content, θ 

(cm3/cm3)

Hydraulic 

conductivity, K

(cm/s)
Table 3. Unsaturated hydraulic property measurements for 10 core samples—Continued

31

ICPP-SCI-V-214 39.40–39.50 -720.82 F 0.3923 3.10×10-8

-1,235.10 F 0.3670 5.25×10-9

-1,320.56 F 0.3600 9.97×10-10

-3,231.76 F 0.2977 ND

-4,694.39 F 0.2378 ND

-52,761.10 F 0.1720 ND

ICPP-SCI-V-214 43.85–43.96 -0.10 A 0.4593 5.20×10-7

-362.39 T 0.4433 8.35×10-8

-488.54 T 0.4314 4.18×10-8

-1,094.35 F 0.4150 6.32×10-9

-998.40 F 0.4106 5.88×10-10

-6,109.27 F 0.3560 ND

-30,815.11 F 0.2755 ND

-82,632.24 F 0.2315 ND

ICPP-SCI-V-214 43.96–44.05 -0.10 A 0.3585 4.59×10-7

-252.12 T 0.3350 8.40×10-8

-495.23 T 0.3228 4.20×10-8

-689.52 F 0.3079 6.35×10-9

-605.87 F 0.3069 5.91×10-10

-3,948.63 F 0.2646 ND

-10,605.80 F 0.2162 ND

-22,685.76 F 0.1663 ND

ICPP-SCI-V-214 56.24–56.33 -0.10 A 0.4546 2.81×10-5

-0.88 T 0.4383 2.47×10-6

-196.50 T 0.4133 1.24×10-6

-433.78 T 0.3907 4.12×10-7

-569.00 T 0.3744 8.23×10-8

-641.66 T 0.3523 3.11×10-8

-815.72 F 0.3272 5.27×10-9

-1,361.23 F 0.3215 5.80×10-10

Borehole

Depth interval 

(m)

Matric pressure, 

ψ (cm-water) Method

Water content, θ 

(cm3/cm3)

Hydraulic 

conductivity, K

(cm/s)
Table 3. Unsaturated hydraulic property measurements for 10 core samples—Continued

32

ICPP-SCI-V-214 56.24–56.33 -2,635.72 F 0.2795 ND

-4,663.04 F 0.2365 ND

-71,395.14 F 0.1533 ND

Borehole

Depth interval 

(m)

Matric pressure, 

ψ (cm-water) Method

Water content, θ 

(cm3/cm3)

Hydraulic 

conductivity, K

(cm/s)
33

Table 4. Textural class percentages and nomenclature using the U.S. Department of Agriculture’s soil 

classification system for 76 bulk and core samples

[Textural class percentages are calculated as the weight of sediment (g) in a given textural class, or particle-size interval 

(in mm), divided by the total weight of sediment (g) analyzed. The textural class name is determined graphically from 

the U.S. Department of Agriculture’s textural triangle and reflects the relative proportions of gravel, sand, silt, and clay 

in a sample.l

Borehole

Depth

interval 

(m)

 Gravel 

(> 2 mm) 

(%)

Sand

(2-0.05 mm)

(%)

Silt 

(0.05-0.002 mm)

(%)

Clay 

(< 0.002 mm)

(%) Texture

ICPP-SCI-V-189 36.59–36.69 0.00 23.19 66.85 9.94 silt loam

ICPP-SCI-V-189 36.69–37.04 0.00 26.41 63.61 9.95 silt loam

ICPP-SCI-V-198 42.84–42.86 0.00 0.00 76.25 23.72 silt loam

ICPP-SCI-V-198 42.86–42.89 0.00 0.00 73.64 26.38 silt loam

ICPP-SCI-V-198 42.89–42.91 0.00 0.00 75.39 24.63 silt loam

ICPP-SCI-V-198 42.91–43.00 0.00 0.00 74.81 25.21 silt loam

ICPP-SCI-V-198 43.05–43.06 0.00 0.00 73.83 26.17 silt loam

ICPP-SCI-V-198 43.13–43.14 0.00 0.00 75.93 24.08 silt loam

ICPP-SCI-V-198 43.22–43.24 0.00 0.00 72.48 27.51 silty clay loam

ICPP-SCI-V-198 43.28–43.29 0.00 0.00 72.93 27.06 silty clay loam

ICPP-SCI-V-204 48.32–48.35 0.00 2.10 79.74 18.12 silt loam

ICPP-SCI-V-204 48.35–48.36 0.00 0.01 78.97 21.05 silt loam

ICPP-SCI-V-204 48.36–48.37 0.00 0.48 76.28 23.25 silt loam

ICPP-SCI-V-204 48.37–48.38 0.00 0.69 77.12 22.20 silt loam

ICPP-SCI-V-204 48.38–48.39 0.00 0.00 78.27 21.74 silt loam

ICPP-SCI-V-204 48.39–48.41 0.00 0.00 73.87 26.16 silt loam

ICPP-SCI-V-204 48.41–48.49 0.00 3.16 78.46 18.43 silt loam

ICPP-SCI-V-204 48.54–48.55 0.00 0.00 75.37 24.64 silt loam

ICPP-SCI-V-204 48.62–48.63 0.00 0.00 74.83 25.20 silt loam

ICPP-SCI-V-204 48.70–48.74 0.00 0.00 73.8 26.21 silt loam

ICPP-SCI-V-205 42.23–42.24 0.00 0.00 76.89 23.16 silt loam

ICPP-SCI-V-205 42.24–42.26 0.00 0.00 75.52 24.52 silt loam

ICPP-SCI-V-205 42.26–42.27 0.00 0.00 76.22 23.71 silt loam

ICPP-SCI-V-205 42.27–42.30 0.00 0.00 76.38 23.65 silt loam

ICPP-SCI-V-205 42.30–42.54 0.00 0.00 76.06 23.97 silt loam

ICPP-SCI-V-205 42.59–42.61 0.00 0.00 75.43 24.59 silt loam

ICPP-SCI-V-205 42.66–42.67 0.00 0.00 75.37 24.67 silt loam

ICPP-SCI-V-205 42.75–42.76 0.00 0.00 73.74 26.26 silt loam

ICPP-SCI-V-205 42.83–42.84 0.00 0.00 75.07 24.92 silt loam

ICPP-SCI-V-205 42.91–42.92 0.00 0.00 76.29 23.68 silt loam
Table 4. Textural class percentages and nomenclature using the U.S. Department of Agriculture’s soil classification 

system for 76 bulk and core samples—Continued

34

ICPP-SCI-V-205 42.99–43.00 0.00 0.00 75.84 24.16 silt loam

ICPP-SCI-V-213 37.50–37.51 0.00 1.09 80.91 17.98 silt loam

ICPP-SCI-V-213 37.58–37.59 0.00 1.12 79.93 18.96 silt loam

ICPP-SCI-V-213 37.65–37.69 0.00 0.82 80.09 19.10 silt loam

ICPP-SCI-V-213 37.69–37.74 0.00 1.36 78.79 19.83 silt loam

ICPP-SCI-V-213 37.79–37.80 0.00 0.00 79.40 20.59 silt loam

ICPP-SCI-V-213 37.80–37.82 0.00 0.11 79.51 20.35 silt loam

ICPP-SCI-V-213 37.91–38.00 0.00 0.03 80.78 19.19 silt loam

ICPP-SCI-V-213 38.00–38.02 0.00 0.00 80.24 19.77 silt loam

ICPP-SCI-V-213 38.02–38.03 0.00 0.00 77.54 22.46 silt loam

ICPP-SCI-V-213 38.03–38.04 0.00 0.00 79.56 20.44 silt loam

ICPP-SCI-V-213 38.04–38.06 0.00 0.00 79.76 20.22 silt loam

ICPP-SCI-V-213 38.06–38.08 0.00 0.00 79.78 20.23 silt loam

ICPP-SCI-V-213 38.08–38.09 0.00 0.00 79.13 20.92 silt loam

ICPP-SCI-V-213 38.09–38.11 0.00 0.04 80.26 19.67 silt loam

ICPP-SCI-V-213 55.79–56.00 0.00 17.37 70.80 11.84 silt loam

ICPP-SCI-V-213 56.00–56.03 0.00 19.56 70.88 9.60 silt loam

ICPP-SCI-V-213 56.03–56.05 0.00 22.48 68.96 8.58 silt loam

ICPP-SCI-V-213 56.05–56.08 0.00 7.94 80.25 11.83 silt

ICPP-SCI-V-213 56.08–56.14 0.00 9.11 74.88 16.04 silt loam

ICPP-SCI-V-214 39.26–39.30 0.00 7.26 79.09 13.65 silt loam

ICPP-SCI-V-214 39.30–39.32 0.00 9.47 77.42 13.10 silt loam

ICPP-SCI-V-214 39.32–39.35 0.00 6.03 80.49 13.46 silt loam

ICPP-SCI-V-214 39.35–39.38 0.00 8.11 78.74 13.15 silt loam

ICPP-SCI-V-214 39.39–39.40 0.00 14.41 74.18 11.45 silt loam

ICPP-SCI-V-214 39.40–39.50 0.00 10.34 76.43 13.18 silt loam

ICPP-SCI-V-214 39.55–39.59 0.00 9.55 76.92 13.54 silt loam

ICPP-SCI-V-214 39.59–39.61 0.00 6.84 79.32 13.85 silt loam

ICPP-SCI-V-214 39.61–39.63 0.00 10.58 77.01 12.39 silt loam

ICPP-SCI-V-214 43.75–43.79 0.00 18.48 66.26 15.28 silt loam

ICPP-SCI-V-214 43.79–43.81 0.00 25.24 61.99 12.79 silt loam

ICPP-SCI-V-214 43.81–43.82 0.00 15.42 70.82 13.77 silt loam

ICPP-SCI-V-214 43.82–43.85 0.00 8.43 72.86 18.66 silt loam

Borehole

Depth

interval 

(m)

 Gravel 

(> 2 mm) 

(%)

Sand

(2-0.05 mm)

(%)

Silt 

(0.05-0.002 mm)

(%)

Clay 

(< 0.002 mm)

(%) Texture
Table 4. Textural class percentages and nomenclature using the U.S. Department of Agriculture’s soil classification 

system for 76 bulk and core samples—Continued

35

Table 5. Specific surface areas for 10 core samples

[Specific surface area (s) is defined as the surface area (m2) of sediment analyzed divided by the weight (g). Five points on the 

nitrogen adsorption isotherm were measured to calculate the surface areas according to Brunauer-Emmett-Teller (BET; 1938) 

theory.]

ICPP-SCI-V-214 43.85–43.96 0.00 7.46 75.30 17.24 silt loam

ICPP-SCI-V-214 43.96–44.05 0.00 4.40 77.23 18.34 silt loam

ICPP-SCI-V-214 44.12–44.13 0.00 0.00 74.03 26.00 silt loam

ICPP-SCI-V-214 44.20–44.21 0.00 0.00 73.00 27.04 silty clay loam

ICPP-SCI-V-214 44.27–44.28 0.00 0.00 71.16 28.81 silty clay loam

ICPP-SCI-V-214 44.28–44.36 0.00 0.00 70.96 29.02 silty clay loam

ICPP-SCI-V-214 55.94–55.95 0.00 46.14 46.75 7.09 loam

ICPP-SCI-V-214 56.02–56.03 0.00 45.41 47.06 7.52 loam

ICPP-SCI-V-214 56.10–56.11 0.00 37.00 51.67 11.31 silt loam

ICPP-SCI-V-214 56.16–56.17 0.00 49.35 40.66 9.94 loam

ICPP-SCI-V-214 56.24–56.33 0.00 23.80 62.77 13.46 silt loam

ICPP-SCI-V-214 56.33–56.37 0.00 12.50 74.69 12.83 silt loam

ICPP-SCI-V-214 56.37–56.40 0.00 1.78 83.47 14.75 silt loam

Borehole Depth interval (m) Specific surface area, s (m2/g)

ICPP-SCI-V-189 36.59–36.69 49.87

ICPP-SCI-V-198 42.91–43.00 34.86

ICPP-SCI-V-204 48.41–48.49 38.13

ICPP-SCI-V-205 42.30–42.54 35.42

ICPP-SCI-V-213 37.91–38.00 23.65

ICPP-SCI-V-213 56.08–56.15 34.62

ICPP-SCI-V-214 39.40–39.50 24.96

ICPP-SCI-V-214 43.85–43.96 48.08

ICPP-SCI-V-214 43.96–44.05 50.36

ICPP-SCI-V-214 56.24–56.33 22.18

Borehole

Depth

interval 

(m)

 Gravel 

(> 2 mm) 

(%)

Sand

(2-0.05 mm)

(%)

Silt 

(0.05-0.002 mm)

(%)

Clay 

(< 0.002 mm)

(%) Texture
36

Table 6. Comparison of particle-size statistics between baked and non-baked sediment[Baked and non-baked intervals were defined based on Munsell (1994) color and proximity to the tops of the interbeds (as noted in the lithologic log f

particle-size statistics (geometric mean and standard deviation) were calculated for the depth intervals identified as baked or non-baked, based on the li

for particle-size measurement.]

Borehole

Top of

interbed

(m)

Depth

interval

analyzed

(m)

Munsell

color

notation

Munsell

color Description

Average

geometri

mean

particle

size (mm

35-m interbed

ICPP-SCI-V-189 36.59 36.59–37.04 7.5YR 6/6 reddish yellow baked 0.0156 ICPP-SCI-V-198 37.80 42.84–43.29 2.5Y 7/4 pale yellow non-baked 0.0038 ICPP-SCI-V-205 38.41 42.23–43.00 2.5Y 7/3 pale yellow non-baked 0.0039 ICPP-SCI-V-213 37.50 37.50–38.11 7.5YR 6/6 reddish yellow baked 0.0054 ICPP-SCI-V-214 39.63 39.26–44.36 10YR 7/3 very pale brown non-baked 0.0085 

45-m interbed

ICPP-SCI-V-204 46.04 48.32–48.74 10YR 7/3 to 7/4 very pale brown non-baked 0.0065 ICPP-SCI-V-215 45.24 45.53–45.95 7.5YR 6/6 reddish yellow baked 0.0968 ICPP-SCI-V-215 45.24 46.10–47.49 7.5YR 6/4 to 6/6 light brown to reddish yellow non-baked 0.0463 

55-m interbed

ICPP-SCI-V-213 54.27 55.79–56.14 10YR 6/4 to 7.5YR 6/4 light yellowish brown to

light brown

non-baked 0.0131 

ICPP-SCI-V-214 55.79 55.94–56.03 5YR 5/6 to 5/8 yellowish red baked 0.0312 ICPP-SCI-V-214 55.79 56.10–56.40 7.5YR 6/4 light brown non-baked 0.0170 ICPP-SCI-V-215 57.29 58.36–59.30 2.5YR 5/6 to 6/6 red to reddish yellow baked 0.1200 ICPP-SCI-V-215 57.29 59.48–60.02 7.5YR 5/4 to 7.5YR 6/4 strong brown to light brown non-baked 0.1053