POOR LEGIBILITY

ONE OR MORE PAGES IN THIS DOCUMENT ARE DIFFICULT TO READDUE TO THE QUALITY OF THE ORIGINAL

SFUND RECORDS CTR

2091915

Sunrise Mountain Landfill

Soil Crust Sampling and Analysis Report

Final

March 16,2006

NOTICE

This document has been prepared using funding provided by the U.S. Environmental Protection

Agency (EPA) under Contract No. 68-C-QO-179. The document has not undergone peer or

Agency review, and has not been approved for publication as an EPA document. This document

is a contract deliverable, and distribution is limited. Mention of corporation names, trade names

or commercial products does not constitute an endorsement or recommendation for use.

This document was prepared forDavid Reisman, Director, Engineering Technical Support Center,

National Risk Management and Research LaboratoryOffice of Research and Development

U.S. Environmental Protection AgencyCincinnati, OH 45268

Jennifer Goetz served as the EPA Project Officer.

The document was prepared under Contract No. 68-C-00-179

with Science Applications International Corporationby:

J. D. (Jim) Oster, PhDEmeritus Soil and Water SpecialistUniversity of California, Riverside

and

Jim RaweSenior Scientist

Science Applications International CorporationFt, Mitchell, KY

For information or comments on the report, please contact

David Reisman at 513-569-7588 or

by e-mail at reisman.david@epa.gov

LIMITATION OF USE OF THIS REPORT

SAIC retained a soils expert, Dr. James D. Oster, who designed and implemented the study

presented in this report. Pursuant to the technical scope of work, SAIC has made no independent

investigations concerning the accuracy or completeness of Dr. Oster's study, methods or

assumption, nor of any information prpvided by EPA.

Because the investigation consisted of collecting and evaluating a limited supply of information,

SAIC and its technical expert may not. have identified all potential items of concern and,

therefore, SAIC warrants only that the project activities under this contract have been performed

within the parameters and scope communicated by EPA and reflected in the contract. This report

is intended for use in its entirety. Taking or using in any way excerpts from this report are not

permitted and any party doing so does so at its own risk.

111

EXECUTIVE SUMMARY

The purpose of the study was to collect and evaluate additional data concerning the existing

landfill soil cover's vulnerability to surface erosion. Soil samples from the surface six inches of

the soil on the Sunrise Landfill were collected and evaluated to determine the existing stability of

soil crusts and whether soil chemical and mineralogical conditions exist that would result in

increasing crust strength over time. If the surface crust is stable, erosion during runoff will be

less than if it is not. The principal finding of this study is that most of the soil in the surface crust

.is not aggregated, and as a result, it is very likely the soil will be dispersed by rain; erosion will

occur. Further, based on studies conducted on natural soils in the Mojave and Great Basin of the

Southwestern U.S., soil aggregation and cementation that reaches a level where a surface crust

will withstand the erosive forces of rainfall, vehicular traffic, and rodent burrowing, is not

expected to occur in the future

Soil samples of the top four tenths of an inch (0.4 inch) of the soil, the surface crust, and of the 3-

to 6-inch depth intervals were obtained from 26 sites on the landfill. The soil methods used

included determination of the percent of water stable aggregates within the approximately 0.4-

inch thick surface crust. The chemical composition of water extracted from saturated-soil paste

of samples of the surface crust was determined to assess the potential effects of salinity and

sodicity (SAR) on aggregate stability. The chemical composition data were also used to

determine the potential presence of cementing agents, other than calcite (CaCO3), using Visual

Minteq to calculate the saturation indices of about 50 sparingly soluble minerals some of which

may contribute to cementation of soil aggregates and the soil crust. The calcite content was also

determined. The possible increase of cementing agents at the soil surface due to evaporation of

IV

saline soil water was also evaluated by comparing the electrical conductivities of the saturated

paste extracts and the Mg, Na, K, Cl, and SO4 concentrations of the surface crust to that of the 3-

to 6-inch depth interval. Finally, the mineralogy of the three most saline crusts was assessed

using X-ray diffraction.

Findings of the study:

1. Most of the surface crust was not aggregated: at most, only about one third of the sampled soil

was aggregated. Since the aggregate stability tests were likely less disruptive than what occurs

during rainfall and runoff, it is very likely that the soil will be dispersed by rain and,

consequently, will become suspended in water that flows over the land surface. Erosion will

occur.

2. Cementing agents are present in the surface crust: calcite accounts for about one-fourth of the

soil in the surface crust, and amorphous silica oxides are also present. However, the calcite

content would need to exceed 50 % for the formation of a calcite-cemented crust to occur. Due to

the low calcite content in the surface crust, the crust will disintegrate when wet by water.

3. A cemented soil layer that will not disintegrate when wet with water cannot be expected to

develop on the surface of soil used to cover the landfill because of soil disturbances from rainfall,

burrowing by rodents, and vehicle traffic. The formation of a cemented soil layer below the soil

surface requires in the order of a million years, and the absence of soil disturbance. These layers

can be exposed by soil erosion. Cemented soil crusts found in Mojave and Great Basin of the

Southwestern U.S., which do not disintegrate when wet with water, are a consequence of erosion

that has removed the overlying soil.

4. Upward movement of water through the soil does occur at the site, and its subsequent

evaporation at the soil surface may increase the calcite and amorphous silica content of the

surface crust. If this increase occurs continually with time, increased aggregate stability may

occur gradually over time. However, the same evaporative processes have occurred over the

millennia associated with the formation of the surface soil in the Mojave and Great Basin of the

Southwestern U.S. Surface crusts in this region are fragile; they slake when wet by water.

Consequently, it is unlikely that a cemented soil crust will form on the surface of soil spread on

the Sunrise Mountain Landfill.

5. The chemical composition of the soil water in the soil crust at the Sunrise Mountain Landfill

is not expected to adversely impact the stability of soil aggregates within the surface crust, or the

rate water can infiltrate into the soil. Gypsum was present in all of the soil samples. Gypsum is

not a cementing agent because of its solubility, but the dissolution of gypsum as the soil wets may

enhance aggregate stability.

6. Based on the published literature about the desert pavements, a desert pavement could

develop on the landfill due to the forces of wind and water over a period of hundreds of years.

However, even if formed, desert pavements do not prevent rill and gully erosion on lands with

slopes as low as 3 - 6 %.

VI

Table of Contents

Notice _ _ ' _ / _ ii

Limitation of Use of this Report . iii

Executive Summary 7 iv

Table of Contents ^ vjj

1.0 Introduction 1

2.0 Sampling 5

2.1 Sampling Locations 5

2.2 Sampling Methods 5

3.0 Evaluation Methods ._" . . " . 12

4.0 Results and Discussion 17

5.0 Summary 32

6.0 References 34

6.1 Cited References 34

6.2 Resource References 35

7.0 Attachments

Attachment 1. Original Sampling LocationsAttachment 2. Sampling Locations, Dates, and TimesAttachment 3. Objective 1. Method to Determine Water Stable AggregatesAttachment 4. Objective 1. Laboratory Data Sheets and Data Sheet NotesAttachment 5. Saturation Indices for 50 Solid and Amorphous CompoundsAttachment 6. Percent of Soil, Excluding Sand, That Consisted of Water Stable

AggregatesAttachment 7. Objective 1. Probability Plots for Percent Water Stable

AggregatesAttachment 8. Potential for the Formation of Cemented Surface CrustsAttachment 9. Potential for the Formation of Desert PavementAttachment 10. Objective 2. Electrical Conductivity (EC) and Sodium

Adsorption Ratio (SAR) of Saturated-Paste Extracts

vn

Attachment 11. Objective 2. Distribution Characteristics of the ElectricalConductivities of Saturated-Paste Extracts (EC, dS/m)

Attachment 12. Objective 2. Distribution Characteristics of the SodiumAdsorption Ratios of Saturated-Paste Extracts (SAR)

Attachment 13. Objective 3a. Electrical Conductivity, pH and ChemicalCompositions of Surface Crust Used to Calculate SaturationIndices With Minteq

Attachment 14. Calcite Content in the Surface Crust ( 0 to 0.4-in) and in the 3 to6 Inch Depth Interval

Attachment 15. Objective 3b. Electrical Conductivity of the Saturated-PasteExtract (ECe) and Concentrations of Elements in the SurfaceCrust (0 -0.4-inch) and the Underlying Soil (3 - 6-inch) - Usedto Assess Impacts of Evapoconcentration on Salt Content of theSurface Crust

Attachment 16 K/T GeoServices X-ray Diffraction Analyses Report

Vlll

1.0 Introduction

The overall goal of this project is to collect and evaluate additional data concerning the

existing landfill soil cover's vulnerability to surface erosion. The credibility of the soil at the

Sunrise Landfill partially depends on the stability of soil crusts that have formed, or may develop

due to cementation by calcite or sparingly soluble amorphous silica oxide. If the crusts are stable,

erosion during runoff will be less than if they are not stable. As stated in the Executive Summary,

the principal finding of this study is that most of the soil in the surface crust is not aggregated,

and as a result, it is very likely the soil will be dispersed by rain; erosion will occur.

During rainfall, at a rate that exceeds the infiltration rate, some rain penetrates the surface

and enters the soil, while the remainder either accumulates on the surface or runs off. Generally,

the infiltration rate is initially high, but decreases exponentially with time to approach a constant

value. Factors that could be responsible for this decrease include: (1) a decrease in the matric

potential gradient which occurs as infiltration proceeds, and (2) the formation of a seal at the soil

surface due to clay swelling, soil aggregate failure, and clay dispersion (Levy et al., 1998).

After the seal at the soil surface dries, a crust may form with a stability that depends, in

part, on the cementation of the clay and silt sized particles into water stable aggregates. Calcite

can cement soil particles together as can amorphous silica oxide (Oster and Singer, 1984); on the

other hand, clay swelling can destroy aggregates as the crust and underlying soil wets during rain.

Clay swelling impacts infiltration rates',""runoff, and erosion. Clay swelling decreases with

increasing soil salinity and decreasing sodium adsorption ratio (SAR)1 of the soil water. The

amount of exchangeable sodium adsorbed on soil surfaces increases with increasing SAR; and

clay swelling increases with increasing exchangeable sodium.

During rainfall several processes occur that can impact the stability of a crust: (1) the

salinity of the water in the surface crust will be reduced, which will increase clay swelling, a

process that can weaken soil aggregates and the crust; (2) crust strength can also decrease if

SAR is calculated using the formula: CNa7 (CCa + CMg) °'5, where the concentrations (C) of Na, Ca, and Mg

are expressed in mmol/L.

wetting dissolves sparingly soluble salts that, if present, may bind soil particles together; and (3)

wetting tends to decrease the strength of whatever form of bonding exists between soil particles

within a crust.

Also, the potential for reduction in erosion due to the potential formation of desert

pavement on the landfill was evaluated. Desert pavements reduce infiltration rates and increase

runoff. Increased runoff results in concentrated flow of water on certain parts of the landscape.

Concentration of water flow increases its erosive power sufficient to cause rill and gully erosion

on desert soils covered by desert pavements that have slopes of about 3 to 6 % (Anderson et al.,

2002; Wells et al., 1985).

The findings of the literature review may not apply to the borrow-pit soils used to cover

the land Sunrise Landfill. When the soil surface is dry, the surface is a moderately hard crust that

is about 0.5 inches thick. The SAIC team, led by Dr. J. D. (Jim) Oster, evaluated the stability of

the existing surface crust by attempting to answer the following questions:

1. What fraction of the soil in the surface crust is in the form of water stable aggregates?2. Are the salinity and adsorbed sodium levels in the soil crust at levels that can cause

failure during wetting of the soil crust due to clay swelling?3. Do chemical conditions exist that indicate sparingly soluble salts could be present in the

surface crust?4. Are sparingly soluble alumino-silicate-carbonate-sulfate salts present under the most

favorable chemical conditions for their formation and presence?5. Can an evapoconcentration process occur to increase the amount of sparingly soluble salt

in the surface inch of soil?

There are two caveats that need to be kept in mind. The processes of wetting and

sieving action during the determination of water stable aggregates (WSA) does not totally

capture the effect of raindrop impact on aggregate stability, nor the mixing and sorting action

involved in movement of water across the soil surface. As summarized by Hillel (2004), in his

discussion of aggregate stability, "Aggregates are more vulnerable to sudden than to gradual

wetting, owing to the air occlusion effect. Raindrops and flowing water provide the energy to

detach particles and transport them away. Abrasion by particles carried as suspended matter

in runoff water may scour the surface and contributes to the overall breakdown of aggregated

structure at the soil surface."

The second caveat is that, even if the results indicate soils at the site form cohesive

crusts and are relatively impermeable and resistant to erosion, this study will not address the

issue of cracking of the crust, which can lead to preferential flows, infiltration, and erosion

along those pathways. "

Extensive information has already been collected regarding the physical properties of

Sunrise Mountain Landfill Site ("site") soils; however, this information does not include chemical

analyses. There is no definitive method to determine the susceptibility of site soils to erosion,

other than observation of the actual effects of rainfall, or simulated rainfall using on-site rainfall

simulators. However, there are a number of indirect soil science methods to evaluate the

susceptibility of surface soils to erosion due to rainfall events. Indirect methods for determining

the susceptibility of surface soils to erosion include aggregate stability measurements and analysis

of electrical conductivity, salinity, and sodicity. These methods are described in the revised final

Quality Assurance Project Plan (QAPP) dated January 27, 2005 (EPA, 2005).

The stability of soil aggregates was determined, using a field method developed by the

U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) based

upon a standard laboratory method utilized by the NRCS Soil Survey Laboratory (USDA, 2004).

The potential impacts of salinity and sodicity of the surface soil layer on erosion and

runoff were assessed using indirect methods, which focus on the solution and solid phase

chemistries of the surface soil layer, including:

• Quirk-Schofield Stability Diagrams to assess the impacts of electrical conductivity (ECe)

and sodium adsorption ratio (SAR) on infiltration and runoff;

• Visual Minteq model to calculate saturation indices for sparingly soluble sulfate and

carbonate salts, which, if present, can increase aggregate stability and soil crusting from

the chemical composition of saturation extracts;

• Assessment of the potential impacts of water evaporation from the soil surface on the

content of sparingly soluble sulfate and carbonate salts in the surface soil layer; and

• X-ray Diffraction (XRD) analysis to determine if insoluble alumino-silicate-sulfate salts

are present.

The resulting data from all of these tests were evaluated at each sample location,

according to the procedures in the (QAPP), to evaluate the potential for surface soil erosion and

runoff. Statistical analysis was done using Minitab™ Statistical Software, release 13.1

An overall assessment of crust stability and erosion potential was made based on results

of the individual methods and the preponderance of the results. The findings of the literature

review and correspondence (Appendix A) between Dr. Robert Graham, Soil Scientist,

Department of Environmental Science, University of California, Riverside, CA, and Jim Oster

were also taken into consideration. ••••-••••

2.0 Sampling

2.1 Sampling Locations

Sampling commenced on March 30, 2005. The revised final Quality Assurance Project

Plan (QAPP), dated January 27, 2005, was endorsed by EPA and, specified that samples would

be collected from 26 locations of a total of 32 locations identified. This approach provided for

omission of six samples based upon field conditions. For example, sites where the crust was

obviously disturbed were not sampled. The original 32 sample locations were listed in Table 3-1

of the QAPP and included as Attachment1 of this report.

Some changes were made in the sampling sequence at the discretion of the Republic site

representative. These changes were made to facilitate access to specific locations and minimize

travel time between sampling locations. All parties agreed that the change in sampling sequence

would not affect sample quality or the project objectives. Samples were collected in the sequence

shown in Table 1. Sample locations where no samples were collected are highlighted in green.

Duplicate samples are highlighted in yellow; in some cases duplicate samples were collected in

different locations than originally planned for convenience. However, because the duplicate

sample locations were assigned in the QAPP on an arbitrary basis (neither randomized nor

intentionally biased toward specific locations), these field changes did not affect the quality of the

data. ..!..:„.

2.2 Sampling Methods

Except where specifically discussed in this report, all samples were collected and handled

according to the procedures identified in the revised final QAPP. The following discussion

briefly describes soil sampling, including all changes from the QAPP, and provides example

photographs to illustrate key steps in that process.

The surface soil (0- to 1-inches deep) was gently broken with the claws of a framing

hammer (Photo 1). In general, soil crust was shallow (0.25 to 0.5 inches) and the soil was a beige

color, dry, and somewhat rocky. Every effort was made to maximize the quantity of soil crust

collected for the shallowest sample so as to provide a best-case estimate of aggregate stability.

Photo 1. Shallow Surface Sampling With Claw Hammer (Location A19).

The size and number of rocks ..varied from one sampling location to another location

(Photos 2 and 3) and also in the area surrounding any given location (Photo 3).

Photo 2. Surface Rock (Location B36).

Photo 3. Sampling Location With V^mfele Surface Rock Content (Location E90)

Where significant quantities of rock were present at the surface, it was sometimes

difficult to collect intact crust samples. Ft* g&ch sample location, samples were collected at areas

with the least visible surface rock (see Fhmt> ,V> avoiding any areas where there appeared to be

recent grading (see Photo 4) and areas where tine soil had apparently deposited in low spots due

to surface water runoff (see Photo 5). In selected locations, pieces of aggregate ranging in area

from 1 to 3 square inches were collected, leaving rocks and fine materials in the sample hole.

Every effort was made to collect surface &oi; samples with the greatest amount of crust to

maximize soil aggregate stability

Crust was placed in a 5-gallon plastic container, mixed, and split according to the procedures in

the QAPP. For the purpose of this report, this method of collection of soil crust samples is

known as "Method 1". Method 1 was later abandoned due to observations made during the field

soil aggregate stability tests. A second method, "Method 2", was implemented and all sample

locations for which Method 1 was initially used were re-sampled using Method 2. In Method 1 ,

broken soil crust (approximately 0.25- tolhl-inches thick) was placed in a 5-gallon bucket for

initial mixing and was then split three times. Rocks larger than approximately 1-inch diameter

were removed by hand from the bucket. Large rocks that were caught on the top rack of the soil

splitter were also discarded. These rocks were removed to facilitate soil splitting and handling,

and were of no value because they would not be analyzed by the field aggregate stability test or

the laboratory soil chemistry methods. The soil splits were poured back into the same bucket

after the first two splits to further mix the :>m; _After the third split, the contents of one collection

tray were poured into a 1-gallon Ziploc bag labeled with the sample number and the word

"Republic" and provided to Republic Services of Southern Nevada (RSSN). The contents of the

other tray were poured into a second l-gsik*?; bag labeled with the sample number and the word

"SAIC". These samples constituted split samples for this location and depth interval.

Photo 4. Evidence of Recent Grading at Location D53.

Photo 5. Sedimentation at Location A128.

The only change in the sampling method was related to shallow (0- to 1-inch) surface

samples for field aggregate stability tests. The QAPP specified that a single shallow sample

would be collected, mixed (after breaking soli clumps or aggregates), and split for each location.

The QAPP further specified that SAIC's portion of the split sample would be used for all tests

(soil chemistry and field aggregate stability). The first three shallow samples were collected

using this method (Method 1). A small portion of the SAIC split was placed in a 1-quart baggie

and transported to the RSSN field trailer fonise in the aggregate stability test.

In the course of doing the aggregate stability tests for the first three samples, a consultant

of Republic, Dr. Craig Benson, suggested that aggregate stability should be determined only from

within the 'cemented' surface crust rather than including 'uncemented' soil directly beneath the

'cemented' crust. The 'cemented' surface crust was about 0.25 to 0.5 inches thick. After a

discussion with EPA representatives, David Reisman and Steve Wall, Dr. Oster recommended

implementation of the suggested approach- Since this involved a change in the procedures

specified in the QAPP, David Reisman.and.. Steve Wall reviewed the QAPP with Republic

representative, Alan Gaddy, and obtained hu> agreement to change the procedures used to sample

the surface soil. Thereafter, a sample of only the 'cemented' surface soil was separately collected

and bagged (see Photo 6) for use in aggregate Stability tests (no size reduction, mixing, or

splitting). Using this method (Method 2), mtea surface soil aggregates were collected from

approximately 0- to 0.5-inches for use m the field aggregate stability test. Subsequent to

collection of the aggregate stability test sample, the shallow surface sample was collected

similarly for soil chemistry and XRD analyses The sample for soil chemistry and XRD analyses

was split and mixed according to the procedures previously described for Method 1.

Photo 6. Bagged Sample of Soil Crust for Aggregate Stability Test.

The 3- to 6-inch deep soil samples were generally a reddish color, sandy and slightly

damp to the touch. In most cases, these samples contained less rock than the 0-to 1 -inch depth

interval. No crust or large soil aggregates were evident in any of these samples.

The 3- to 6-inch depth interval was collected by removing the top 3 inches of soil from a

hole approximately 9- to 12-inches in diameter to prevent "cross-contamination" of the deeper

sample by the shallower sample. The soi! was then collected from 3 to 6 inches using the

hammer claws to loosen the soil and collecting the soil in a scoop (see photo 7). The collected

soil was placed in a 5-gallon bucket for initial mixing and was then split three times (see photo 8).

As with the shallow samples, rocks with ;s diameter of greater than approximately 1 -inch were

removed and returned to the original sampling hole. The soil splits were poured back into the

same bucket after the first two splits to further mix the soil. After the third split, the contents of

one collection tray (see the soil splitter in photo 8) were poured into a 1-gallon Ziploc bag labeled

with the sample number and the word "Republic". The contents of the other tray were poured

into a second 1-gallon bag labeled with the sample number and the word "SAIC". These samples

constituted split samples for this location and depth interval.

Photo 7. Sampling 3- to 6-Inefe larval With Claw Hammer (Location A19).

10

Photo 8. Soil Splitter.

11

3.0 Evaluation Methods

The evaluation methods are discussed in the sequence of the questions introduced in theIntroduction of this report. The results are discussed in Section 4.

Objective 1. Qualitatively evaluate aggregate stability to wetting by water. [Question 1].

Jim Oster and Cliff Anderson determined the aggregate stability of the soil within ~0.4-

inch thick surface crusts obtained at 26 sites on the landfill. The sampling and aggregate stability

determinations were done on March 30 and 31, 2005 on the same day the samples were obtained.

This was done in a building at the base of the landfill owned by the Republic Services of

Southern Nevada (RSSN).

The method used (Attachment 1) was developed by the U.S. Department of Agriculture,

National resources Conservation Service (NRCS). It is a modification (Seybold and Herrick,

2001) of the method proposed by Kemper and Rosenau (1986). The laboratory procedures were

written by C.A. Seybold in 1999 and downloaded from an NRCS website in late 2004 (USDA,

2004).

Three modifications were made to the method:

(1) Samples were not air-dried, because the surface soil was already air-dry.

(2) Step 3 was modified: the sieves containing the soil were set on a wet sponge covered

with paper napkin both cut to a size that fit within the inside diameter of the sieve

holder. The wet sponge, in turn, was set on a wet cloth.

(3) The drying chamber (Figure 8.3; Attachment 1) used for most of the analyses was

made from a cardboard box, and a larger hairdryer was used than shown in Figure

8.3. The small dryers provided in the soil-quality field kit tended to overheat and cut

off before the drying steps were complete.

Cliff Anderson did all of the weighing (steps 1, 2, 6 and 8; Attachment 1) and made the

entries into the data sheets (Attachment 2). Each determination was done using 10.0 +/- 0.01 g of

soil that passed through the 2-mm sieve (step 1 and 2). Jim Oster did steps 3,4, 5, 7 and 8 for 25

of the 26 samples. Anderson did these steps for 1 of the 26 samples.

12

Operator technique was expected to impact the results because of the sensitivity of the

aggregates to the rate the sieve is moved up and down in the water (Step 4, Attachment 1). To

assess this expectation, both Oster and Anderson did three determinations of the aggregate

stability (Steps 3, 4, 5, 7, and 8) on the same samples obtained at three sites. These samples were

randomly selected from those available in the building at the time the selections were made.

Signed copies of the data sheets (Attachment 2) were given to RSSN before leaving on

March 31. The following week the data .were transferred to an excel file by Oster. Attachment 2

contains annotations made by Jim Oster after March 31.

Objective 2: Estimate the impacts of ECe and SAR on surface soil infiltration and runoffusing the Ayers and Westcot Stability Diagrams, which is based on a diagram originallyproposed by Quirk and Schofield (1955). [Question 2]

The electrical conductivities (ECe) and SAR of the water extracted from saturated soil

pastes were compared to water quality guidelines (Figure. 1) used to assess whether infiltration

rates are expected to decrease due to clay swelling and dispersion (Ayers and Westcot, 1985).

Clay swelling is a key process that affects aggregate stability.

o i '?_", ' . . V " 5

Electrical Cpiiductjvity of Water, EC, in dS/m

Figure 1. Ayers and Westcot Stability Diagram (AWSD) used to assess potential impacts ofECe and SAR on the rate water infiltrates into soil (Ayers and Westcot, 1985).

13

Also, an assessment was made, using multiple linear regression analysis, to determine if

ECe and SAR of the saturated-paste extract affected WSA.

Objective 3: Determine the potential for crust formation from the composition of thesaturation extracts. [Question 3].

The presence of sparingly soluble salts (e.g. calcite and gypsum) and oxides of aluminum

and silica will impact soil crust stability and strength. Cementation by calcite, gypsum, and by

oxides of aluminum and silica would increase crust stability. Dissolution of gypsum during

rainfall will increase soil water salinity and reduce SAR, both of which will reduce clay swelling,

and thereby its negative effect on crust stability. The chemical composition of saturated-paste

extracts will be used to determine if sparingly soluble salts and/or minerals may be present in the

surface crusts. This objective is divided into two parts.

3a: Determine the possible presence of calcite, gypsum, and oxides of aluminum and silicain surface crusts.

The possible presence of calcite, gypsum and oxides of aluminum and silica was assessed

using the Visual Minteq model (http://www.lwr.kth.se/English/OurSoftware/vminteq/). This

model is a Windows version of MINTEQA2 ver 4.0, which was released by the USEPA in 1999.

MINTEQA2 is a widely used chemical equilibrium model for the calculation of metal speciation,

solubility equilibria, and other data for natural waters. For this project, the pertinent calculations

that Visual MINTEQ performed included:

• Ion speciation using equilibrium constants from the MWTEQA2 database, which has

been updated using the most recent NIST data to contain > 3000 aqueous species and >

600 solids.

• The saturation indices for 50 solid and amorphous compounds (Attachment 3).

Visual Minteq was used to calculate the saturation indexes for minerals from the

chemical composition, including aluminum and silica, and pH of saturated-paste extracts. The

saturation index is calculated by comparing the apparent solubility product of a mineral, based on

the composition of the soil solution, to its accepted (textbook value) solubility product. An index

14

equal to or greater than 0.0, hereafter referred to as a positive index, indicates the mineral could

precipitate and may be present in the crust. A negative index indicates the opposite.

Specific options for pH, ionic strength and concentration need to be chosen from several

that provided by Minteq. The following choices were made: pH was fixed at the value measured

in the saturated-paste extract; ionic strength was calculated from the data; and the data were

entered in concentration units of mmol/L,

The aluminum concentrations in. the saturation extracts were lower than the detection

limits. Consequently, the following equation was used to calculate the aluminum concentration

(Bloom, 1999) from the pH of the saturation extracts:

Log (Al+3) = 9.6-3 pH.

Two sets of saturation indices Were calculated. One for the saturated-paste using the ion

concentrations of the saturated-paste extracts. The second was for the soil water at the field water

content. For the later, the ion concentrations of the extracts were multiplied by the ratio:

saturated-paste water content divided by the field water content. This assumes the ionic

concentrations increase linearly with decreasing water content - e.g. if the water content is

decreased 10 fold, the concentrations increase 10 fold, hereafter referred to as the water content

assumption. The resulting estimates do not take into account the impacts of exchange and salt

precipitation reactions that occur as the soil water content decreases. As the water content

decreases, the amount of exchangeable sodium and magnesium will increase resulting in lower

concentrations of these ions in the soil,water than calculated using the water content assumption.

The increase in exchangeable sodium and magnesium will be matched by a decrease in

exchangeable calcium, which will tend to increase the concentration of calcium in the soil water.

However, some or all of this calcium will precipitate as calcite and gypsum lowering the

bicarbonate and sulfate concentrations from those calculated using the water content ratio

assumption. These reactions are difficult .to model (Oster and McNeal, 1971). At this time, the

Oster/McNeal model is not available, and to the best of my knowledge no other model exists.

The FORTRAN code of the model is.currently undergoing revision into C++ and may be

available within several months. However, for the purposes of this study, the water content

assumption will provide insights into the possible minerals that were present in the soil before

water was added to prepare saturated-pastes.

15

The limitation of the Minteq method to estimate saturation indices is that reaction

kinetics can prevent salt precipitation when the saturation index for the mineral is positive. In

other words, a positive result only indicates the potential for the formation of sparingly soluble

mineral that could bind soil particles together thereby adding stability to a surface crust.

3b: Determine if evapoconcentration of salts is occurring in the surface crust that couldenhance the content of sparingly soluble salts (calcite and gypsum) and oxides of aluminumand silica. [Questions 3 and 5]

Evaporation of water from the soil surface can cause the slow upward movement of

dissolved salts that will lead to increasing concentrations of dissolved salts in the surface crust.

This process is called evapoconcentration. It was evaluated by comparing the ECe and the Na,

Mg, K, Cl, and SO4 concentrations in the surface crust (0 - 0.4-inch depth interval) to the values

obtained for the 3 - 6-inch depth interval. If evapoconcentration is occurring the values for these

parameters will be higher in the crust than in the 3- to 6-inch depth intervals. Ca and HCO3

concentrations were purposefully excluded from this evaluation, as they are the least soluble

elements, because calcite precipitation significantly limits their concentrations.

The values for ECe, Na, Mg, K, Cl, and S04 were all log-normally distributed.

Consequently the statistical analysis was done on log (base e) transformed data. The 26 sample

locations were considered to be blocks and the two depth intervals were considered to be

treatments within block.

If evapoconcentration has occurred it indicates that the amounts of slightly soluble sulfate

and carbonate minerals in the surface soil may be increasing with time. In turn, one may infer

that the following may be increasing with time: binding mechanisms that link soil particles

together, and associated crust strength and development.

Objective 4. Utilize X-ray Diffraction (XRD) analysis of three samples in the 0 to 1-

inch depth interval to determine if insoluble alumino-silicate-sulfate salts are

present.

XRD analyses were used to confirm the inferences drawn in the work done

related to Objective 2. With XRD one can determine if insoluble alumino-silicate-sulfate

salts are present in dry soils. X-ray diffraction was used on three of the most saline soils

16

in the surface inch of soil, to determine if sparingly soluble alumino-silicate-carbonate -

sulfate salts, including gypsum and calcite, were present. In order to meet this objective,

three samples were selected from the 32 samples from the 0- to 1-inch interval on the

basis of ECe and the water content of fhe_saturation paste extract (SP). The greatest

chance that XRD would find these rninerals_was for the samples with the highest ECe and

SP: the most saline soils when wet, and consequently the most saline when dry.

Consequently the three samples with the highest product ECe * SP -were selected.

17

4.0 RESULTS AND DISCUSSION

Section 4.0 is organized to follow the sequence of the project objectives as originally

presented in Section 3.6 of the Revised Final QAPP dated January 27, 2005. These objectives,

and the experimental methods utilized to evaluate each objective are restated in Section 3 of this

report. The evaluation of each of the four objectives is individually discussed followed by a

summary of all results. For each objective, applicable data are tabulated for each location,

appropriate statistics are provided for the data set, and the overall data set is discussed in terms of

soil crust stability and erosion potential at the site,

Objective 1. The following findings are based on 1) the determinations of WSA made by

Jim Oster on crust samples obtained at 25 sites, 2) the one determination made for the 26th site by

Cliff Anderson, 3) an evaluation of measurement sensitivity based on differences in operator

technique and associated consequences in interpretations of the data, 4) a comparison of the WSA

obtained in this study to that obtained on different soils reported by the authors of the method we

used (Seybold and Herrick, 2001), and 5) correspondence about cementation processes with Dr.

Robert Graham (soil mineralogist, Dept. Environ. Sci., Univ. of California, Riverside, Ca) and

literature review of desert pavements.

1. The average percent of water stable aggregates (WSA) for the 25 determinations made

by Jim Oster was 19% (Table 1 and Attachment 6). These results support the position

that the surface soils are not stable and are subject to erosion. Other statistical

characteristics of the WSA data obtained by Jim Oster are:

a. Twenty five percent of the WSA values are less than 14%, indicating very lowaggregate stability in one-quarter of the samples tested;

b. Fifty percent are less than 17%, which is lower than the average of 19 %, indicatingthe data are not normally distributed (Attachment 7A and 7B).

18

c. Seventy five percent are less than 25%, indicating low aggregate stability for themajority of the locations tested,

Table 1. Water Stable Aggregate (WSA) Determinations by Jim Oster(From Attachment 6)

Samplesite

136810121517192124262833353840 -4244474951535557

Sieveplussoil

Sieveplus

aggregates

Sieveplussand

Aggregatesminus sand

SoilminusSand

?•-- giain -

73.273.173.173.173.073.572.972.673.173.173.173.073.173.072.973.073.172.973.473.173.173.273.573.073.2

66.465.266.566.366.667.566.766.866.166.967.566.766.966.067.468.367.168.968.265.767.366.867.266.867.9

65.764.666.065.364.065.465.465.864.765.865.465.566.064.566.265.565.865.566.465.165.465.765.865.666.7

0.70.60.51.02.62.11.31.01.41.12.11.20.91.51.22.81.33.41.80.61.91.11.41.2

• 1.2

7.58.57.17.89.08.17.56.88.47.37.77.57.18.56.77.57.37.47.08.07.77.57.77.46.5

Average % ' WSA Determinations by Oster

Water StableAggregates

(WSA)

%9.37.17.012.828.925.917.314.716.715.127.316.012.717.617.937.317.845.925.77.524.714.718.216.218.5

19

19

2. Cliff Anderson obtained a WSA of 78 % for the one determination he made. Although

this is an unusually high value, it is not an outlier, based on the log-normal distribution of

the data obtained by Jim Oster (Attachment 7C).

3. Aggregate stability was sensitive to differences in operator technique. Cliff Anderson

obtained a higher average WSA, 33.8%, than did Jim Oster, 16.7% for the nine

determinations (Table 2) that both made on samples obtained at sites 1, 17, and 38. Each

made triplicate determinations of WSA on these three samples.

Table 2. Results obtained by Oster and Anderson for replicate determinations ofpercent water stable aggregates for samples obtained at three sample sites.

Sample site

111171717383838

Oster Anderson

% water stable aggregates

9.34.29.714.723.218.137.313.520.3

21.120.329.347.940.073.718.414.139.2

The averages for each sample number for each operator and an overall average for each

operator are reported in Table 3. Jim Oster obtained an average of 16.7% for the three

sample sites and Cliff Anderson obtained an average of 33.8.

20

Table 3. Averages obtained by Oster and Anderson for replicate determinations ofpercent water stable aggregates for samples obtained at three sample sites.

Sample site

11738Average

Oster Anderson Average

% water stable aggregates

7.718.623.7

,^16.7

23.653.923.933.8

15.736.323.8

It is noteworthy that, while there was a significant difference in results between the two

operators, the average results from both operators indicate that aggregate stability is low,

supporting the observation that a stable crust is not present at the site and erosion of

surface soils is likely due to rainfall and surface runoff.

4. How do the WSA values we obtained compare to previously reported values using the

same method for other soils? Seybold and Herrick (2001) reported WSA values for

several soils with different soil textures, which together with organic matter content

would be expected to affect WSA. Soil texture was not determined for the samples we

worked with. This requires determination of the fraction of the soil that is sand, silt and

clay. Only the percent sand was measured during the aggregated stability determinations

we made. For samples obtained at sites 1, 17, and 38, used to assess the impacts of

operator technique, the fraction of sand ranged from 26 to 30 %, uncorrected for the

calcite content of the soil (about 25 %), and from 34 to 40 % when corrected to calcite

content. For either range of percent sand, the possible soil textures could be: silt loam,

loam, clay loam, or clay (Fig. 3.3; Hillel, 2004). Seybold and Herrick (2001) obtained a

WSA of 69 to 70 % for a Cullen day loam from Virginia, and 61 to 62 % for a Capic

loam from Missouri. The lower WSA values we obtained are most likely the

consequence of the lower organic matter content of desert soils as compared to soils used

by Seybold and Herrick. Organic matter is known to increase aggregate stability (Hillel,

2004)

21

5. What is the potential for the formation of a surface layer of soil that is will prevent soil

erosion? Two aspects of this question are addressed: a) the potential for the formation of

cemented soil crusts at the soil surface, which will not disintegrate when wet with water,

based on what is known about cementation processes that occur in the desert soils in the

desert regions of southwestern U.S (Attachment 8, which is an unedited copy of email

correspondence with Robert Graham, private communication, 2005.) and b) the potential

for the formation of desert pavement and whether it would prevent erosion (Attachment

9) if formed on the soil surface.

a. Cemented soil crusts at the soil surface, which will not disintegrate when wet with

water, cannot be expected to form because of repetitive disturbances caused by wetting -

as occurs during rainfall —, or by vehicle traffic or by grading during cover maintenance.

A soil layer cemented by calcite CaCO3, or amorphous silica (opaline silica), or both, can

form below the soil surface over a time period in the order of a million or more years, at

depths which preclude any disturbance by rainfall, rodent burrowing, or vehicle traffic.

These cemented layers can become exposed as a result of soil erosion.

b. Desert pavement is a mosaic of rocks that forms at the surface of desert soils.

Pavements form as a consequence of two natural processes: episodic rain and wind

erosion. Desert pavements reduce infiltration rates and increase runoff. Increased runoff

results in concentrated flow of water on certain parts of the landscape. Where desert

pavements have developed under natural conditions in the Mojave Desert, a process that

can take approximately 100 years, the erosive forces of runoff tend to cause both rill and

gully erosion on land slopes as low as 3 to 6 % (Wells et al. 1985; Anderson et al. 2002).

Conclusions: Most of the aggregates within the surface crust disintegrated, or slaked, when

wet by water at seventy five percent, or more, of the sampling sites. The cementation due to

22

calcite, amorphous silica, or both was not adequate to prevent aggregate disintegration. Since the

aggregates will disintegrate when wet with water, so will the crust. Since the crust on the soil

surface is subjected to greater physical forces during rainfall - raindrop impact, rapid wetting,

dispersive and erosive effects of flowing water - than imposed by the method used to determine

aggregate stability, the existing crusts at the sites sampled can be expected to disintegrate during

rainfall. Any runoff that occurs on the site can be expected to result in rill and gully erosion.

Formation of a calcite- or silica-cemented surface crust, which will not disintegrate when

wet with water, cannot be expected to occur on soils used to cover the Sunrise landfill.

Formation of a mosaic of rocks on the soil surface, known, as a desert pavement, may

occur, but where desert pavements have developed under natural conditions in the Mojave Desert,

a process that can take approximately 100 years, the erosive forces of runoff tend to cause both

rill and gully erosion on land slopes as low as 3 to 6 %.

Objective 2. SAR and ECe measurements were made on 26 samples by the analytical

laboratory according to the methods described in Revised Final QAPP dated January 27, 2005.

These methods are summarized in Section 3 of this report. SAR increased linearly with ECe for

the saturated paste extracts of the soil in the surface crusts obtained at the landfill (Figure 2; data

are presented in Attachment 10).

The red line in Figure 2 shows where the lower line in Figure 1 (Section 3) would be

located. The location of the EC - SAR values relative to the red line shows that had the data been

plotted on Figure 1, all the combinations would have been located in the area labeled "no

reduction in infiltration." Consequently, the chemical composition of the soil water in the soil

crusts is not expected to reduce infiltration, or adversely impact the stability of soil aggregates

within the surface crust.

This conclusion was consistent with the lack of correlation between EC and SAR and

WSA as indicated by the results of a multiple linear regression analysis (Table 4). This

23

regression analysis was done using both non-transformed and loge-transformed WSA, SAR, and

EC data. All were log-normally distributed (Attachments 7, 11, and 12). Transformation had no

impact on the conclusion. The R2 values were low for both, ranging from 7.6 to 7.7 %.

Sunrise SAR and EC of surface crust

SAR = 1.01ECe + 12R2 = 0.9477 ^X"

100 120

Figure 2. The relationship between the ECe and SAR of extracts obtained from saturatedsoil pastes for the soil crusts obtained at the Sunrise Landfill in March 2005.

The sign of the coefficients for ECe and SAR in regression equations 1 and 2 are

consistent with expectations (Table 4; A and B): aggregate stability is expected to increase with

increasing ECe because the number preceding EC (the coefficient for EC) is positive and to

decrease with increasing SAR because the coefficient for SAR is negative.

24

Table 4. Results from multiple linear regression analysis using ECe and SAR as factors topredict the percent of water stable aggregates (WSA).

A. Untransformed data

WSA = 29.2 + 0. 438 ECe - 0. 545 SAR; R2 = 7.6 % (regression equation 1)

Predictor Coefficient . JJE T PCoefficient

Constant 29.2 7,25 4.03 0.0001ECe 0.438 JL5.51 0.79 0.435SAR -0.545 0,528 -1.03 0.313

B. Transformed data

Ln(WSA) =-4.04 + 0.226 Ln(ECe) - 0.538 Ln(SAR); R2 = 7.7 % (regression equation 2)

Predictor Coefficient SE T PCoefficient

Constant 4.04 1,646 2.46 0.022ECe 0.226 0,668 0.34 0.738SAR -0.538 0.999 -0.54 0.595

Conclusions: The chemical composition of the soil water in the soil crusts is not

expected to negatively impact infiltration, or adversely impact the potential formation of soil

aggregates or the stability of soil aggregates within the surface crust.

There was no correlation between aggregate stability and ECe and SAR, indicating no

causal relationship exists. Whatever cementing agents exist within the aggregates, their

cementing properties are not affected by the salt concentration or composition of the soil solution.

If either ECe or SAR do not affect aggregate stability, it is unlikely that either will affect crust

strength, soil infiltration, runoff, and erosion during rain.

Objective 3. Potential Crust Formation

The potential for crust formation from the composition of saturation paste extracts for 26

samples was made according to the procedures established in the Revised Final QAPP dated

25

January 27, 2005 and summarized in Section 3 of this report. The evaluation of results is

presented in two parts.

Objective 3a. Table 5 summarizes the results of the Visual Minteq model analysis of

saturation indices. See Attachment 13 for compositions used to calculate saturation indices. For

the saturated-paste water content of the 26 samples of surface crusts, one exceeded the ionic

strength limits of Minteq, and six 'exceeded this limit at the field water content. Consequently,

the sample number (N) actually utilized for the saturated-paste water content (Table 5 A) was 25

(26 - 1), and for the field water content (Table 5 B), N was 20 (26 - 6).

Table 5. Minerals for which the saturation indices were greater than or equal to 0.0 and thepercent of soil crust samples where this was the case (based on saturation paste and fieldwater contents).

A. Saturated-Paste Water Content. [Attachment 13 A]

Mineral Chemical Components

Aragonite

Calcite

Chalcedony

Chrysotile

Cristobalite

Dolomite (disordered)

Dolomite (ordered)

Gypsum

Huntite

Magnesite

Quartz

Sepiolite

Sepiolite (A)

SiO2 (am.gel)

Ca, CO3

Ca, CO3

Si, O, H

Mg, Si, O, H

Si, O, H

Ca, Mg, C03

Ca, Mg, C03

Ca, SO4, H20

Ca, Mg, C03

Mg, C03

Si, O, H

Mg, Si, O, H

Mg, Si, O, H

Si, O

Percent of Samples with a

Saturation Index Greater

Than or Equal to Zero

(N=25)

92

96

84

24

28

28

92

52

12

12

100

20

26

SiO2 (am,ppt)

Vaterite

Si,0

Ca, C03 20

B. Field water content. [Attachment 13 B]

Mineral Chemical components

Anhydrite

Aragonite

CaCO3xH2O

Calcite

Chalcedony

Chrysotile

Cristobalite

Dolomite (disordered)

Dolomite (ordered)

Gypsum

Huntite

Magnesite

Quartz

Sepiolite

Sepiolite (A)

SiO2 (am,gel)

SiO2 (am.ppt)

Vaterite

Ca,SO4

Ca,CO3

Ca,CO3

Si.O.H

Mg, Si, O, H

Si,O,H

Ca, Mg, C03

Ca, Mg, CO3

Ca, SO4. H20

Ca, Mg, CO3

Mg,C03

Si,O, H

Mg,Si,0,H

Mg, Si, O, H

Si.O -

Si,O

Ca, CO3

Percent of Samples with a

Saturation Index Greater

Than or Equal to Zero

(N = 20)

100

100

70

100

100

12

60

100

100

100

85

70

100

100

25

95

95

100

Of the 50 mineral and amorphous compounds (Attachment 5) that are included in Minteq,

the saturation indices of 16 were positive at the water content of the saturated-paste extracts

(Table 5A). The saturation indices for calcite, aragonite, dolomite, and quartz met these criteria

27

for over 90 % of the saturated-paste extracts (Table 5A). Calcite and quartz were observed in

XRD (See Objective 4).

At the field water content (Table 5B), the saturation indices of 18 mineral and amorphous

compounds were positive. The percent of samples with positive indices were greater than at the

saturated-paste water content. For example, the saturation index for gypsum was positive for 52

% of the samples at the saturated-paste water content as compare to 100 .% at the field water

content. At the field water content, the saturation index for calcite was positive for 100 % of the

samples. Both gypsum and calcite were observed in the XRD (See Objective 4).

Two additional minerals had positive saturation indices at the field water content:

anhydrite (CaSO4-H20) and CaCO3'H20. Anhydrite basically is gypsum with one less water

molecule in the structure, and CaCO3-H20 is hydrated calcite. Neither were observed in the XRD

(See Objective 4).

The calcite content was determined by the analytical laboratory. All of the samples from

both depths, 0 to 0.4-inch and 3 to 6-inch, contained calcite (Attachment 14). The range for the 0

to 4-inch depth was from 16.8 to 34.3 % with an average of 26.2%. The range for the 3 to 6-inch

depth was from 20.4 to 34.3 % with an average of 25.5%. This is consistent with the results

obtained from the Minteq analysis as well as the XRD results (Objective 4).

Objective 3b. Evapoconcentration did cause the ECe and K, Mg, Na, SO4, and Cl

concentrations in the saturated-paste extracts of the soil crust to be higher than in the underlying

soil (Table 6; Attachment 15). The probability the averages were not significantly different was

very low, <0.013 (Table 6). The statistical analysis was done using loge transformed data

because, like ECe (Attachment 11), the distribution of the ion concentrations was log-normal.

Because some of the concentrations of K and Cl were less than 1.0, 1.0 was added to all

the concentrations of these ions before the logarithms (base e) of the numbers were calculated

28

(Table 6). After back transformation (equal to e average)) 1.0 was subtracted from the number to

obtain the back transformed averages (Table 6).

Table 6. The average electrical conductivity of saturate-paste extracts (ECe), and theconcentrations of the most soluble elements in the soil. 1.0 was added to the K and Clconcentrations before the logarithm of the numbers were calculated.

Depth ECe K Mg Na SO4 ClInch dS/m mmolc/L

Averages of log(e) transformed data(C1 +

(K+l) 1)0-0.4 2.313 1.530 3.539 3.552 4.335 3.9093.0-6.0 1.630 1.165 2.860 2.628 4.019 2.697Probability 0.000 0.013 0.000 0.000 0.003 0.000

Back transformed averages0-0.4 10.1 3.6 34.4 34.9 76.3 48.83.0-6.0 5.1 2.2 17.4 13.8 55.6 13.8

Conclusion: Even after a wet year (about 10 inches between October ] 2004 and April 1, 2005

which is over two times the average annual rainfall), which should have resulted in a significant

reduction of the soluble salts in the surface crust, in a month's drying time, evapoconcentration

was sufficient to move the salts back up into the surface crust. In the absence of rain, further

increases in soluble salts could occur, as well as increases in the content of sparingly soluble salts

(calcite and gypsum) and oxides of aluminum and silica.

Objective 4. XRD analyses were performed by K/T Geoservices, Inc. according to the

methods prescribed in the Revised Final QAPP dated January 27, 2005 and summarized in

Section 3 of this report. The following results are based on the report prepared by James P.

Talbot, P.G, of K/T GeoServices, 4993 Kiowa Trail, Argle TX 76226, KJT File No.:

Z05166 (Attachment 16).

Very little sample preparation was done. Only dry hand grinding in an agate mortar and

pestle. Powder X-ray diffraction requires that the sample be finely ground which cannot be

29

achieved with hand grinding. The samples were hand ground to minimize the changes in

mineralogy that can occur with more vigorous grinding methods. The XRD are summarized in

Table X of Attachment Y

XRD shows a wide variation in calcite content in the three samples (24 to 66%). Calcite

is the common carbonate mineral found in soils. Dolomite is also present but in minor amounts.'

These XRD results are consistent with the results of the Visual Minteq model analysis reported in

Table 5 A and 5B.

XRD confirmed gypsum was present, consistent with the results of the Minteq model

analysis. (Table 5A and 5B). Gypsum is much more soluble than calcite. Fine gypsum particles,

or gypsum coatings on soil particles located at the soil surface, would tend to be dissolved by

rain. It would not be an effective cementing agent.

Quartz was also present in all samples and cristobalite may have been present; both

results are consistent with the results of the Minteq analysis (Table 5A and 5B). Most of the

quartz in these samples is probably in the form of discrete quartz grains, which are very stable at

surface conditions. Quartz is not considered a cementing agent, but according to Dr. R. Graham,

(soil mineralogist, University of California, Riverside, private conversation 1 June 2005),

cristobalite -a more soluble form of quartz -- would be a potential cementing agent.

Amorphous forms of silica, in particular SiO2 (am, ppt) possibly were present (Tables 5A

and 5B) and would be potential cementing agents, however, these would not be detectable by

XRD methods because they do not have a crystalline structure.

The clay mineral sepiolite was possibility present (Tables 5A and 5B) based on the

Minteq analysis. However, the clay content of all the samples was low (Table 1, page 2 of,

Attachment 16) and sepiolite is not a common clay mineral in arid zone soils. Consequently, its

absence in the XRD results was to be expected.

30

No alumino-silicate-sulfate minerals were present.

Conclusion: The cementation of soil crusts and aggregates that exists - see objective 1 — is likely

due to calcite, and possibly cristobalite andamorphous silica..

31

5.0 SUMMARY

The principal findings of the study were:

1. Most of the soil within the surface crust was not aggregated. Since the aggregate

stability tests were likely less disruptive than what occurs during rainfall and runoff, it is very

likely that the soil will be dispersed by rain, and consequently will become suspended in water

that flows over the land surface. Erosion will occur.

2. Cementing agents are present in the surface crust: calcite accounts for about one-

fourth of the soil in the surface crust, and amorphous silica oxides are also present. However, the

calcite content would need to exceed 50 % for the formation of a calcite-cemented crust to occur.

Such a crust would not slake when wet by water, and the soil aggregates formed from the crust

would be stable in water.

3. Upward movement of water through the soil does occur at the site, and its subsequent

evaporation at the soil surface may increase the calcite and amorphous silica content of the

surface crust. If this increase occurs continually with time, increased aggregate stability may

occur gradually over time. However, the same evaporative processes have occurred over the

millennia associated with the formation of the surface soil in the Mojave and Great Basin of the

Southwestern U.S. Surface crusts in this region are fragile; they slake when wet by water.

Consequently, it is unlikely that a cemented soil crust will form on the surface of soil spread on

the sunrise landfill.

4. The formation of a cemented soil layer below the soil surface requires in the order of

a million years or more, and the total absence of soil disturbance from rainfall, burrowing by

rodents, and vehicle traffic. Cemented soil layers form below the soil surface, over a time period

in the order of a million or more years, at depths that preclude any disturbance. These layers can

32

be exposed by soil erosion. Cemented soil crusts found in Mojave and Great Basin of the

Southwestern U.S. are a consequence of soil erosion.

5. The chemical composition of the soil water in the soil crust at the Sunrise Mountain

Landfill is not expected to adversely impact the stability of soil aggregates within the surface

crust or the rate water can infiltrate into the soil. Gypsum was present in all of the soil samples.

Gypsum is not a cementing agent because of its solubility, but the dissolution of gypsum as the

soil wets may enhance aggregate stability.

6. Based on the published literature about the desert pavements, a desert pavement could

develop on the landfill due to the forces of wind and water over a period of hundreds of years.

However, even once formed, desert pavements do not prevent rill and gully erosion on lands with

slopes as low as 3 to 6 %. ; ..,;..,.

33

6.0 REFERENCES

6.1 Cited References

Anderson, K., S. Wells, and R. Graham. 2002. Pedogenesis of vesicular horizons, Coma Volcanic Field,Mojave Desert, California. Soil Sci. Soc. Am. J. 66:878-887.

Ayers and Westcot, 1985. Water quality for agriculture. FAO Irrigation and Drainage Paper 29, Rev. 1.FAO, Rome.

Bloom, P.R. 1999. Soil pH and pH buffering, pp. B.333-B.350 M.E. Sumner (ed.) Handbook of SoilScience. CRC Press, Boca Raton.

Hillel, D. 2004. Introduction to Environmental Soil Physics, Elsevier Academic Press, New York, ISBN0-12-348655-6.

Graham, R. 2005. Private communication.

Kemper, W.D. and R.E. Rosenau. 1986. Aggregate stability and size distribution, p 425-442. In Page,A.L., Miller, R.H., and Kenney, D.R. (ed.), Methods of soil analysis: Part 1. Physical and MineralogicalMethods. Agron. Monogr. 9. 2nd edn. ASA and SSSA, Madison, WI.

Levy, G.J., I. Shainberg, and W.P. Miller. 1998. Physical properties of sodic soils, p 78-94. In Sumner,M.E., and Naidu, R. Sodic soils: Distribution, Properties, Management, and EnviornmentalConsequences. Oxford University Press, New York.

Oster, J.D. 1982. Gypsum usage in irrigated agriculture: a review. Fertilizer Research 3:73-89.

Oster, J. D., and B. L. McNeal. 1971. Computation of soil solution composition variation with watercontent for desaturated soils. Soil Sci. Soc. Amer. Proc. 35:436-442.

Oster, J.D., and M.J. Singer. 1984. Water penetration problems in California soils. Dep. Land, Air andWater Resources Paper no. 10011. Univ. of California, Davis.

Quirk, J.P., and R.K. Schofield. 1955. The effect of electrolyte concentration on soil permeability. J. SoilSci. 6:163-176.

Seybold, C.A. and I.E. Herrick. 2001. Aggregated stability kit for soil quality assessments. Catena 44:37-48.

USDA. 1999, Updated 2002 U.S. Department of Agriculture, Natural Resources Conservation ServiceSoil Quality Test Kit Guide at http://soils.usda.gov/sqi/assessment/test kit.html#How.

34

USEPA. 2005. Quality Assurance Project Plan: Field Sampling and Analysis of Cover Soils atthe Sunrise Landfill in Las Vegas, NV, Revision 2. Prepared by Science ApplicationsInternationa! Corporation (SAIC). January 27, 2005.

Wells, S.G., J.C. Sohrenwend, B.D. Turrin, and K.D. Mahrer. 1985. Late Cenozoic landscapeevolution on lava flow surfaces of the Cima volcanic field, Mojave Desert, California.

6.2 Resource References

Oster, J. D., and F.W. Schroer. 1979. Infiltration as influenced by irrigation water quality. SoilSci. Soc. Am. J. 43:444-447. "";",

Oster, J.D., I.Shainberg, and I.P. Abrol. 1999. Reclamation of salt affected soils.p. 659-691. In R.W. Skaggs and J. van Schilfgaarde (ed.) Agricultural drainage. Agron. Monogr.38. ASA, CSSA, SSSA, Madison, WI.

Quirk, J.P. 2001. The significance of the threshold and turbidity concentration in relation tosodicity and microstructure. Aust. J. SoilJ£gs. 39:1185-1217.

35

ATTACHMENT 1ORIGINAL SAMPLING LOCATIONS

SampleNumber

SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-

Map SampleLocationNumber

A10A10

A128A128A19A19A19A93A93E90E90E90D83D83D53D53D63D63D64D64D33D33D36D36D23D23D23D77D77E59E591313

E84E84E21

Duplicate

D

D

D

Sample Depth Interval(inches BLS)

0-13-60-13-60-13-63-60-13-60-10-13-60-13-60-13-60-13-60-13-60-13-60-13-60-13-63-60-13-60-13-60-13-60-13-60-1

Sample Size(pounds)

222222222222222222222222222222222 .222

ATTACHMENT 1ORIGINAL SAMPLING LOCATIONS

SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-SL-

E21E22E22E25E25E25E23E23E18E18B23B23B31B31B31C74C74B46B46B8B8

B41B41B41C20C20C24C24C43C43C76C76C8C8

D

D

D

3-60-13-60-10-13-60-13-60-13-60-13-60-10-13-60-13-60-13-60-13-60-13-63-60-13-60-13-60-13-60-13-60-13-6

22222222222222222 •22222222222222222

Attachment 2. Sampling Locations, Dates, and Times

SampleNumber

(h)

&Aa-=* '!t- "•**«**«.*.«

;NA a~"SL-01 b

SL-02 "

SL-03 b

SL-04 b

SL-05 b

SL-06 b

SL-07 b

SL-08SL-09SL-10

SL-11SL-12SL-13SL-14

;NAC ,.iNA1<r

m*::SampleNumber

.NA e.. .SL-15SL-16SL-17SL-18SL-19SL-20SL-21SL-22SL-23SL-24SL-25SL-26SL-27SL-28SL-29SL-30

MapSample

LocationNumber

A93

A93 :

A19

A19

A10

A10

A10

A128

A128

D83D83E90

E90D53D53D53

D63;D63

D64Map

SampleLocationNumber

D64

D36D36D33D33D77D77D23D23D23E18E18E23E23E25E25E25

ApproximateDistance &

Direction FromStake

. - ,NA ; .;./:'NA ;

3ft N

3ft N3ft N3ft N3ft N

5 f t N

5 f t N2 f t E2 f t E12ftE12f tE2 f t E2 f t E2 f t E

: NA

• N A ' . ;: : ; - . ; . . NA :;;:•-;

ApproximateDistance &

Direction FromStake

,- NA •" . • : • • • : :3 f t N3 f t N5 f t W5 f t W6 f t E6 f t E

SftNNESftNNESftNNE

l O f t Nl O f t N1 2 f t S1 2 f t S

30 ft SSW30 ft SSW30 ft SSW

SampleDate

OMMpSv03/30/05

03/30/05

03/30/05

03/30/05

03/30/05

03/30/05

03/30/05

03/30/05

03/30/0503/30/0503/30/05

03/30/0503/30/0503/30/05

03/30/0503/30/05

03/30/05 :

03/30/05 • ! :Sample

Date

03/30/05

03/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/0503/30/05

SampleStartTime

::1020

1033

1047

1124

1230

1300

1325

:1350 .

-1355

SampleStartTime

1400

1425

1445

1505

1530

1600

1625

FieldDuplicate

(D)

c

D

d

D

". .'"v*:. =•-

; '--''' '.^ .:'

FieldDuplicate

D

D

SampleDepth

Interval(inches BLS)

0-1

. , ' , ' .3-6;.., :

0-1

3-6

0-1

3-6

3-6

0-1

3-6

0-13-60-1

3-60-10-13-6o-r3-6

0 ,0-1SampleDepth

Interval(inches BLS)

3-60-13-60-13-60-13-60-13-63-60-13-60-13-60-10-13-6

SampleSize

(pounds)

2

2. : .2

2

2

2

4

2

2

222

2242

, 2 ' ;

L: 2 .

- ' 2 . - ,Sample

Size(pounds)

2- ;

2222222242222242

SL-31SL-32SL-33SL-34SL-35SL-36SL-37SL-38SL-39SL-40SL-41SL-42SL-43SL-44SL-45SL-46SL-47SL-48SL-49SL-50SL-51SL-52SL-53SL-54SL-55SL-56SL-57SampleNumber

SL-58NA

NA

SL-03B

SL-04B

SL-05B

SL-06B

SL-07B

SL-01BSL-02BSL-35BSL-36B

SL-37SL-33BSL-34B

E84E84E22E22B31B31B31B23B23B46B46B8B8B41B41C41C74C74C20C20C8C8

C76C76C43C4313

MapSample

LocationNumber

13A19

A19

A10

A10

A10

A128

A128

E59E59B31B31

B31E22E22

I f t S EI f t S E8f tE8 f t E15f tN15f tN15ftN3 f t E3 f t E

S f t N WS f t N W15f tW1 5 f t W2 0 f t S20 ft S20f tS8 f t E8 f t E

**

10 ft NW10 ft NW2 f t N W2 f t N W

3 f t S3 f t S

*

ApproximateDistance &

Direction FromStake

.*

NA

NA*

*

*

*

*

****

***

03/31/0503/31/0503/31/0503/31/05

03/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/0503/31/05

SampleDate

03/31/0503/31/05

03/31/05

03/31/05

03/31/05

03/31/05

03/31/05

03/31/05

03/31/0503/31/0503/31/0503/31/05

03/31/0503/31/0503/31/05

0745

0815

0842

0910

0936

1004

1037

1110

1137

1210

1228

1337

1404Sample

StartTime

1437

1455

1516

1537

1616

1644

D

D

FieldDuplicate

C

e

r

(

'f

f

tt

g

g

ggg

0-13-60-13-60-10-13-60-13-60-13-60-13-60-13-63-60-13-60-13-60-13-60-13-60-13-60-1

SampleDepth

Interval(inches BLS)

3-60-1

3-6

0-1

0-1

3-6

0-1

3-6

0-13-60-10-1

3-60-13-6

222224222222222422222222222

SampleSize

(pounds)

22

2

2

2

2

2

2

2224

2 '22

a No sample collected due to lack of observable crust (very rocky and on a steep slope)b "Crust" (0- to 1-inch) samples for the aggregate stability test collected along with the 0- to 1-inch soil

chemistry sample by scraping the surface 1 inch with the claws of a framing hammer and collecting thesample into a bucket, mixing and splitting the sample, and then bagging the sample (method 1). After3 samples this method was changed because the method collected non-aggregated fines that are belowthe surface crust as well as the crust. A new method (Method 2) was developed. Method 2 involvedscraping only the actual crust (approximately V4 to '/2 inch thick) and bagging it for the aggregatestability test (no mixing and no splitting). Non-aggregated soil below the crust but in the top 1 inch ofsoil was not collected. These three crust_samples were re-collected in day 2 as close as possible to theoriginal sample point. In addition, corrgSptJnding 0- to 1- inch and 3- to 6-inch soil samples were re-collected at the same new location so that the soil chemistry results would correspond with theaggregate stability results. After replacement samples were collected the original samples werediscarded per EPA direction. : :

c Duplicate originally scheduled for A19 byUyas missed in the field; duplicate taken at A10 instead.d Duplicate originally scheduled for E90 but was missed in the field; duplicate taken at D53 instead.e No sample collected due to surface crust disturbance.f Sample re-collected using method 2 for the aggregate stability sample and standard methods for the o-

to 1-inch and 3- to 6-inch soil chemistry samples. Samples re-collected at A10 (SL-03B, SL-04B, andSL-05D) and A128 (SL-06B and SL-07B), but not at A19 where there was no visible crust that couldbe collected intact. Replacement samples SL-01B and SL-02B were collected at E59.

g Sample labels for aggregate stability samples fell off in transport so that these samples could not beassigned to a definite location. Soil chemistry sample labels were intact. Re-collected aggregatestability samples and corresponding 0- to 1- inch and 3- to 6-inch samples so that aggregate stabilityresults would better correspond with soil cjj-mjstry results.

h No samples were collected at C24_md E21 because the maximum number of samples(58) was reached (the other four sample sets not collected are explained in otherfootnotes to this table). -^---

* Exact sample location not recorded, but all samples were within 30 feet and mostwere within 10 feet of the stake.

Attachment 3. Objective 1. Method to Determine Water Stable Aggregates(From USDA Soil Test Kit Guide, Chapter 8, August 1999)

8. Aggregate Stability

Aggregate stability measures the amount ofstable aggregates against flowing water. It is recom-mended that aggregate stability be determine^ on the top three inches of surface soil. The soilsample should be air-dried before determining aggregate stability.

Did You Know?Soil aggregates protect organicmatter within their structurefrom microbial attack. Forma-tion and preservation of aggre-gates allows organic matter tobe preserved in the soil.

Materials needed to measure aggregate stability:

• 2-mm sieve (3-inch diameter)• 0.25-mm sieves (2.5-inch diameter)• terry cloths• 400-watt hair dryer and drying chamber• calgon solution (about 2 tbsp of calgon

per 1/2 gallon of tap water)• bucket or pan• scale (0.1 g precision)• distilled water

Considerations: If the soil is moist, air-dry a sample before determining aggregate stability.When taking a soil sample, care should taken,not to disrupt the soil aggregates.

Sieve the Soil Sample

Transfer about a 1/4 cup of air-dried soil to the 2-mm sieve. Shake the sieve gently and collect thesoil passing through the sieve. Try to pass all of thesoil through the sieve by gently pressing the soilthrough with your thumb (Figure 8.1).

Weigh Sieved Soil Sample

Weigh the 0.25-mm sieve, and record its weight onthe Soil Data worksheet. Weigh out about 10 g ofthe sieved soil from Step 1 (make sure the soil ismixed well before taking a subsample). Record theexact weight on the Soil Data worksheet.

Slowly Wet the Soil Sample in Sieve

Saturate one of the terry cloth sheets with distilledwater and lay it flat. Place the 0.25-mm sievecontaining the soil on the wet cloth, allowing thesoil to wet up slowly (Figure 8.2). Wet the soil for five minutes. Figure 8.2

NOTE: A container (bucket or pan) of distilled water is needed for Step 4. The water tem-perature should be at or near the temperature of the soil.

18

Figure 8.1

Wet Sieve the Soil

• Place the 0.25-mm sieve with soil in the container filled with distilled water, so that thewater surface is just above the soil sample.

• Move the sieve up and down in the water through a vertical distance of 1.5 cm at therate of 30 oscillations per minute (one oscillation is an up and down stroke of 1.5 cm inlength) for three minutes. Important: Makesure the aggregates remain immersed inwater on the upstroke.

Dry Aggregates

After wet sieving, set the sieve with aggregates on adry piece of terry cloth, which will absorb theexcess water from the aggregates in the sieve. Thenplace the sieve containing the aggregates on thedrying apparatus (Figure 8.3). Allow the samplesto dry using the low power setting. Figure 8.3

NOTE: Be careful when drying the soil to prevent particles from blowing out of the sieves. Itmay be necessary to put a cover over the top of the sieves to keep aggregates in place.

(6) Weigh Aggregates

After drying, allow the aggregates and sieve to cool for five minutes. Weigh the sievecontaining the aggregates. Record the weight of the sieve plus aggregates on the Soil Dataworksheet.

Disperse Aggregates in Calgon Solution

• Prepare calgon solution. Immerse the sieve containing the dried aggregates in thecalgon solution (do not completely immerse the sieve). Allow the aggregates in thesieve to soak for five minutes, moving the sieve up and down periodically. Only sandparticles should remain on the sieve.

• Rinse the sand on the sieve in clean water by immersing the sieve in a bucket of wateror by running water through the sieve.

Dry and Weigh Sand

• Remove excess water by first placing the sieve containing the sand on the dry terrycloth, then placing it on the drying apparatus. Allow sand to dry.

• After drying, allow the sand and sieve to cool for five minutes. Weigh the sieve con-taining the sand. Record the weight of the sieve plus sand on the Soil Data worksheet.

CALCULATIONS:Water Stable Aggregates (% of soil > 0.25mm) = (weight of dry aggregates - sand)

(weight of dry soil - sand)

19

100

Attachment 4. Objective 1. Laboratory Data Sheets

perator. Ulster r<?.c ', /hSample Number | Sieve # ! Sieve + soil [Sieve + aggregates Sieve + sand [Aggregates - sand dry soil - sand % aggrega comments

1&\-' JHJS=F§-J- fp-^ft^^f- T7^-5J?. _

-<*•***•-<>

Attachment 4. Objective 1. Laboratory Data Sheets

Data sheet notes (Attachment 4).

1. Sample number 9999 did not exist. The data with this sample number,the first line of data in the data sheet was an example.

2. 4th column -- Sieve #: We used six sieves, labeled A - F.

3. Last column -- Comments:

Operator initials indicate who did steps 3, 4, 5, 7, and 8.

Samples without an asteriskj/vere obtained from intact soil crusts,which were approximately 0.4 inches thick.

Samples marked with an asterisk in the last column indicate thesample was obtained beforejhe field sampling procedures werechanged. These samples were obtained from the 0 - 1-inch depthinterval. These results werejiot included in the data assessment.These sites were resampled and aggregate stability wasdetermined a second time orrsamples obtained from intact soilcrusts.

4. Rows are lined out because a misstep was made during the determination ofaggregate stability. These included: not removing the sponge before starting step4 and in one instance the loss of soil particles because they were blown out ofthe sieve container during the drying steps. In each case the correspondingsample analysis was rerun from the beginning.

5. In May, Rawe, Oster and Anderson confirmed that one sample was notlabeled correctly in the field: sample 11 on the data sheet was actuallysample 12.

Attachment 5. Objective 3aSaturation indices were calculated by Minteq for the followingminerals.

AI(OH)3 (am)AI(OH)3 (Soil)AI2O3

AI4(OH)10SO4AIOHSO4AluniteAnhydriteAragoniteArtinite.Boehmite;Brucite, |CaCO3xH2OCalciteChalcedonyChrysotileCristobaliteDiasporeDolomite (disordered)Dolomite (ordered)Epsom iteEttringiteGibbsite (C)GypsumHaliteHalloysiteHuntiteHydromagnesiteImogoliteK-Alum

AI+3

AI+3

AI+3

H+1H+1K+1Ca+2Ca+2H+1H+1;

Mg+2:Ca+2Ca+2|H4SiO4!Mg+2H4SiO4H+1Ca+2Ca+2Mg+2Ca+2AI+3Ca+2Na+1AI+3Mg+2Mg+2AI+3K+1

3

3

3

4131

' 121

" ! • • 211

-22

-21111231121411

H2O

H2O

H2O

AI+3AI+3AI+3SO4-2CO3-2Mg+2AI+3H2OCO3-2CO3-2H2OH4SJO4H2OAI+3Mg+2Mg+2SO4-2AI+3H2OSO4-2CMH4SiO4Ca+2C03-2H4SJO4AI+3

-3 H+1

-3 H+1

-6 H+1

1 SO4-21 SO4-22 SO4-2

1 CO3-22 jH2O

-2 IH+11 H2O

1 H2O

2 H2O2 CO3-22 CO3-27 H203 SO4-2

-3 H+12 H2O

1 H2O4 CO3-2

-2 H+13 H2O2 SO4-2

10 H2O1 H2O

-6 H+1

5 H20

6 H2O

-6 H+1

-12 H+1

-6 H+1

6 H2O-6 H+112 H2O

38 H2O

Attachment 5 continued

KaoliniteKCILimeMagnesite

Mg(OH)2 (active)

Mg2(OH)3CI:4H2OMgCO3:5H2OMirabiliteNatronNesquehonitePericlasePortlanditeQuartzSepioliteSepiolite (A)

SiO2 (am.gel)

SiO2 (am.ppt)SpinelThenarditeThermonatriteVaterite

AI+3K+1H+1Mg+2

Mg+2

Mg+2Mg+2Na+1Na+1Mg+2H+1Ca+2H4SiO4Mg+2H2O

H4SiO4

H4SiO4H+1Na+1Na+1Ca+2

2111

2

1111112

-232

-2

-21111

H4Si04CI-1Ca+2CO3-2

H2O

CI-1-CO3-2SO4-2C03-2CO3-2Mg+2H2OH2OH4SJO4Mg+2

H2O

H2OMg+2SO4-2CO3-2CO3-2

1

1

-2

-35

. 101031

-2

-43

2

1

H2O

H20

H+1

H+1H2OH20H2OH2OH2OH+1

H+1H4SIO4

AI+3

H2O

-6 H+1

7 H20

-0.5 H2O-4 H+1

4 H2O

Attachment 6. Percent of the soil, excluding sand, that consisted of water stable aggregates

Samplesite

1

36810121517192124262831333538404244474951535557

Operator

Oster

OsterOsterOster .OsterOsterOsterOsterOsterOsterOsterOsterOster

AndersonOsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOster

Sieveplussoil

73.2

73.173.173.173.073.572.972.673.173.173.173.073.172.973.072.973.073.172.973.473.173.17.3.273.573.073.2

Sieveplus

aggregates

66.4.

65,266,5...66,3._.66.667.5. ...66.766.866.166,9__67.566,7_.66.971.366.067.468.367.168.968.265.767.366,8.67.266.867.9 „

Sieveplussand

65.764.666.065,364.065.465.465.864.765.865.465.566.065.664.566.265.565.865.566.465.165.465.765.865.666.7

Aggregatesminussand

0.7

0.60.51.02.62.11.31.01.41.12.11.20.95.71.51.22.81.33.41.80.61.91.11.41.21.2

SoilminusSand

7.5

8.57.17.89.08.17.56.88.47.37.77.57.17.38.56.77.57.37.47.08.07.77.57.77.46.5

Waterstable

aggregates

<v/o9.37.17.012.828.925.917.314.716.715.127.316.012.778.117.617.937.317.845.925.77.524.714.718.216.218.5

Naturallogarithm of

% waterstable

aggregates

2.231.951.952.553.363.262.852.692.812.713.312.772.544.362.872.893.622.883.833.252.013.212.692.92.792.92

Attachment 6. Percent of the soil, excluding sand, that consisted of water stable aggregates

Samplesite

13

- 681012

1517

192124

26283133353840424447

4951535557

Operator

OsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOster

AndersonOsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOsterOster

Sieveplussoil

73.2

73.173.173.173.073.572.972.673.173.173.173.073.172.973.072.973.073.172.973.473.173.173.273.573.073.2

Sieveplus

aggregates

66.465.266.566.366.667.566.766.866.166.967.566.766.971.366.067.468.367.168.9 "•"68.265.767.366.867.266.867.9

Sieveplussand

65.7

64.666.065.364.065.465.465.864.765.865.465.566.065.664.566.265.565.865.566.465.165.465.765.865.666.7

Aggregatesminussand

0.7

0.60.5

1.02.62.1

1.31.01.41.12.1

1.20.95.7

1.51.22.81.33.41.80.6

1.9

1.11.41.21.2

SoilminusSand

7.5

8.57.1

7.89.08.17.56.88.4

7.37.7

7.57.17.38.56.77.57.37.47.08.07.77.57.77.46.5

Waterstable

aggregates

9.3

7.17.012.828.925.917.314.716.715.127.316.012.778.117.617.937.317.845.925.77.5

24.714.718.216.218.5

Naturallogarithm of

% waterstable

aggregates

2.23

1.951.952.553.363.262.852.692.812.713.312.772.544.362.872.893.622.883.833.252.013.212.692.92.792.92

Attachment 7. Objective 1. Probability plots for % water stable aggregates, % ag. A.Untransformed % ag obtained by Oster, B. Log(e) transformed, Ln % ag, obtained byOster. C. Log(e) transformed, Ln % ag, obtained by Oster and Anderson.

Normal Probability PlotA. Oster

.QTO

O

CL

.999

.99

.95 -

.80 -

.50 -

.20 -

.05 -

.01 -

.001 -

15 25

% a.q35 45

.0TO

.999

.99

.95

.80

.50

.20

.01

.001

Normal Probability PlotB. Oster log transformed

2.0 2.5 3.0

In %ag3.5

Normal Probability PlotC. Oster and Anderson log transformed

jz

Pro

bab

.999 -

.99 -

.95 -

.80 -

.50 -

.20 -

.05 -

-

.001 -

- . .. . . _^--Jf*' •

*>^^

^^"2 3 4

Ln % ag

Attachment 8. Potential for the formation of cemented surface crusts that will not

disintegrated when wet with water (Appendix A, private communication, Robert

Graham, 2005).

The following comments are based on email correspondence that occurred

between Graham and Oster between July 27 and August 1, 2005. Dr. Robert

Graham is a soil scientist that has specialized in the mineralogy of soils in the

Southwestern U.S. He is a professor in the Department of Environmental

Sciences, University of California, Riverside, CA 92521

1. Cemented soils usually have more than 50 % CaCO3 (calcite) and some have

nearly 100% CaCO3.

2. The formation of cemented CaCO3 horizons, calcic horizons, generally occur

at depths below the soil surface which reflect the long-term depth of leaching by

rainfall, and the lack of any disturbance, including that caused by rainfall, vehicle

traffic or burrowing by rodents.

3. Over a period of time, which likely is in the order of a million or more years,

the calcic horizon becomes so plugged with precipitated CaCO3 that it is

extremely hard and will not disintegrate, or slake, in water. This is called a

petrocalcic horizon. These horizons can be found at the surface, but it is because

they have been exposed by erosion.

3. Soils cemented by amorphous silica (opaline silica) have about 4 % silica.

4. If a soil horizon cemented by amorphous silica, samples of the horizon will not

slake in HCL, and is called a duripan.

5. It is common to find amorphous silica precipitated with CaCOs.

6. Calcic horizons have not been observed to form in the surface soils in the

Mojave or Great Basin in Southwestern U.S. The surface crusts in this region

are relatively fragile: they slake in water, and are easily broken by traffic or rodent

burrowing.

Conclusions

Cemented soil crusts at the soil surface, which will not disintegrate when wet with

water, cannot be expected to form on any soil used to cover the landfill because

of repetitive disturbances caused by wetting -- as occurs during rainfall —, or by

rodent burrowing, or by vehicle traffic.

A soil layer cemented by CaCOS, or amorphous silica (opaline silica), or both,

can form below the soil surface over a time period in the order of a million or

more years, at depths which preclude any disturbance by rainfall, rodent

burrowing, or vehicle traffic. These cemented layers can become exposed as a

result of soil erosion.

Attachment 9. Potential for the Formation of Desert Pavement

Desert pavement is a mosaic of rocks that forms at the surface of desert soils.

Pavements form as a consequence of two natural processes: episodic rain and

wind erosion (Wells et al., 1984; Anderson, 2002; private communication, Robert

Graham, 2005). Where desert pavements have developed under natural

conditions in the Mojave Desert, a process that can take ~ 100 years, the erosive

forces of runoff tend to cause both.rill and gully erosion on land slopes as low as

s-6%. ;:

Desert pavement develops as a result of the following soil forming processes:

1. For rocks that exist on the soil surface, the role of rain is to wash soil particles

that have accumulated between rocks, and on the surfaces of rocks, to below the

rocks. If rain is sufficient, some of the soil particles can also be moved down-

slope in surface runoff. .''I'.".""

2. Between rains, deposition of wind borne dust particles between and on top of

the exposed rocks, replenishes the source of soil particles. During rain, these

become dispersed and washed downward into cracks that formed in the dry

soil. This process of dust deposition and downward translocation during rain

results in accumulation of soil material under the desert pavement. The result is

that desert pavements rise upwards on a vertically accumulating soil deposited

by water and wind erosion.

3. Upon drying the soil material below the rock develops a "bread-like" pore

structure - a structure filled with small cavities - that is typically 1 to 3 inches

thick. These cavities develop as a consequence of entrapped air that is unable

to rise to the soil surface when the soil is wet. This "bread-like" structure is called

a vesicular structure.

4. The rate water moves through a vesicular layer, in which the pores do not

collapse when the soil is wet, is reduced by the presence of air filled pores. The

cross sectional area for water flow is reduced and the water-conducting pores

are not well connected. Consequently infiltration rates are reduced and runoff is

increased.

Conclusions

Desert pavements reduce infiltration rates and increase runoff. Increased runoff

results in concentrated flow of water on certain parts of the landscape.

Concentration of water flow increases its erosive power sufficient to cause rill and

gully erosion on lands in the Mojave Desert with slopes of about 3 - 6 % that are

covered by desert pavement. Future formation of desert pavements on the

Sunrise landfill cannot be expected to form stable desert pavement able to

withstand the erosive forces associated with runoff on slopes exceeding about 3

- 6 %.

References

Anderson, K., S. Wells, and R. Graham. 2002. Pedogenesis of vesicular

horizons, Coma Volcanic Field, Mojave Desert, California. Soil Sci. Soc. Am. J.

66:878-887.

Wells, S.G., J.C. Sohrenwend, B.D. Turrin, and K.D. Mahrer. 1985. Late

Cenozoic landscape evolution on lava flow surfaces of the Cima volcanic field,

Mojave Desert, California.

Graham, R. 2005. Private communication.

Attachment 10. Objective 2. Electrical conductivity, EC, and sodium adsorptionratio, SAR, of saturated-paste extracts, percent water stable aggregates w/osand, %WSA, and the associated lpge transformed numbers.

site

1

3

6

8

10

12

15

17

19

21

24

26

28

31

33

35

38

40

42

44

47

49

51

53

55

57

Op'

1

1

1

1

1

1

1

1

1

1

1

1

1

2

1

1

1

1

1

1

1

1

1

1

1

1

EC

10.60

31.00

4.40

1.80

34.00

6.20

8.90

16.00

114.00

34.00

3.00

26.70

3.60

5.10

4.50

8.50

2.60

21.00

3.00

12.00

28.30

7.10

34.00

3.10

19.00

2.30

SAR

25.00

47.00

13.00

8.70

51.00

23.00

22.00

31.00

118.00

49.00

9.70

42.00

11.00

14.00

13.00

21.00

9.50

40.00

8.30 ..

25.00

42.00

19.00

53.00

11.00

47.00

9.30

%WSA

7.70

7.10

7.00

12.80

28.90

25.90 _

17.30

18.60

16.70

15.10

; ""• 27.30

._. ' 16.00

12.70

78.10

17.60

." 17.90

23.70

17.80

45.90

25.70

7.50

; 24.70

14.70

18.20

16.20

_ . . ._ . 18.50

LnWSA

2.041

1.960

1.946

2.549

3.364

3.254

2.851

2.923

2.815

2.715

3.307

2.773

2.542

4.358

2.868

2.885

3.165

2.879

3.826

3.246

2.015

3.207

2.688

2.901

2.785

2.918

LnEC

2.361

3.434

1.482

0.588

3.526

1.825

2.186

2.773

4.736

3.526

1.099

3.285

1.281

1.629

1.504

2.140

0.956

3.045

1.099

2.485

3.343

1.960

3.526

1.131

2.944

0.833

In SAR

3.219

3.850

2.565

2.163

3.932

3.135

3.091

3.434

4.771

3.892

2.272

3.738

2.398

2.639

2.565

3.045

2.251

3.689

2.116

3.219

3.738

2.944

3.970

2.398

3.850

2.230

1Op represent operator, where operator 1 is J.D.(Jim) Oster, and 2 is Cliff Anderson.

Attachment 11, Objective 2. Multiple Linear Regression Analysis - using ECe and SARas factors to predict the percent of water stable aggregates (WSA).

This regression analysis was done using both non-transformed and loge-transformed WSA, SAR,

and ECe data. All were log-normally distributed (Attachments 7 and 12). Transformation had no

impact on the conclusion. The R2 values.were.IQW.for both, ranging from 7.6 to 7.7 %. The sign

of the coefficients for ECe and SAR in regression equations 1 and 2 are consistent with

expectations (Table 4; A and B): aggregate stability is expected to increase with increasing ECe

because the number preceding ECe (the coefficient for ECe) is positive and to decrease with

increasing SAR because the coefficient for SAR is negative.

Results from multiple linear regression analysis using ECe and SAR as factors to predict

the percent of water stable aggregates (WSA).

A. Untransformed data

WSA = 29.2 + 0. 438 ECe - 0. 545 SAR; R2 = 7.6 % (regression equation 1)Predictor

ConstantECeSAR

Coefficient

29.20.438-0.515

SECoefficient7.250.5510.528

T

4.030.79-1.03

P

0.00010.4350.313

B. Transformed data

Ln(WSA) =-4.04 + 0.226 Ln(ECe) - 0.538 Ln(SAR); R2 = 7.7 % (regression equation 2)Predictor

ConstantECeSAR

Coefficient

4.040.226-0.538

SECoefficient1.6460.6680.999

T

2.460.34-0.54

P

0.0220.7380.595

Attachment 12, Objective 2. Distribution characteristics of the electricalconductivities of saturated-paste extracts (EC, dS/m).

Normal Probability Plot

.999 -|

.99 '

.95 I

co .50.aQ .20

Q_.05 -.01

.001

50 100

EC

.999 |

.99 -

.95 -j

IT .so -i

Q..20

.05

.01 -

.001I

0.5 1.5 2.5 3.5

Ln (EC)4.5

Attachment 12. (Continued) Objective 2. Distribution characteristics of thesodium adsorption ratios of saturated-paste extracts (SAP).

Normal Probability Plot

&

Pro

babi

^

Pro

babi

.999 -

.99

.95

.80

.50

.20

.05 -

.01 -

.001

.999

.99 -

.95

.80 -

.50 -

.20 -

.05 -

.01

.001

.0

. »'

•

•

20 70 120

SAR

*.-• '• .--"'

t- •-'"..,-••»

i;i

i

3 4

Ln (SAR)

Attachment 13 Objective 3a Electrical conductivity, pH and chemical compositions of surface crust used to calculate

saturation indices with Minteq.Chemical composition of saturated-paste extracts of the surface

A

Recheck

RecheckRecheck

-, ' > i

Recheck

Recheck

Recheck

0 - 0.4-inchcust IDSL-1BSL-3BSL-6BSL-8SL-10SL-12SL-15SL-17

:, ;SL-19SL-21SL-24SL-26SL-28SL-31SL-33BSL-35BSL-38SL-40SL-42SL-44SL-47SL-49SL-51SL-53SL-55SL-57

ECe dS/m10.630.84.42.1

40.411.410.619.6

1;14J3

33.83.0

31.83.75.14.58.52.6

20.82.4

11.928.37.1

36.73.1

21.02.3

pHe7.227.437.327.377.567.477.537.6

;7.64 ':

7.697.4

7.597.087.237.2

7.327.2

7.657.427.417.037.147.867.357.5

7.32

Ca

18.2516.5

17.2515.75

1719.2520.2516.2520.5

14.7515.517.5

16.2518.2517.2521.5

15.2513

14.524

25.2518.25

1815.25

1817.25

crust.

K

11.2530.950.770.26

13.992.562.819.46

3t.71;10.740.268.7

0.510.511.282.810.64

40.920.183.583.321.02

15.350.776.650.51

Mg

25.5158.836.581.65

57.5922.6312.7533.32

300:29127.93

5.7654.3

79.05

11.5214.81

3.751.01

1.6518.9263.3513.1747.1

735.382.06

Na

69.13226.52

15.221.09

276.0961.3

55.65113.04

}| 1435.22' 292.17

2.17207.83

3.716.96

1051.32.83

153.480.87

73.04218.7

40281.34.35

146.961.74

HCO3mmol/L

2.643.68

41.364.083.083.362.645.76

4.082.483.68

22.242.164.162.68

122.483.763.282.888.243.6

4.243.36

S04

39.91101.0222.45

18.4100.3929.3122.45

; 42.4j 3382.25

'I '1 49.0318.0875.4521.8219.9520.5825.8817.46

107.8816.2125.8850.8224.0182.6221.2

49.8918.71

Cl

85.6238.321.40.9

251 .7299.5

79.09122.2211195.3249.5

9.6196.18

635.3

2883.14.4

123.60.9

122.6281.6

55.4250.21

- 7.5164.28

0.8

Si

0.710.180.5

0.750.250.540.570.290.070.180.610.320.750.570.640.570.790.540.570.790.210.570.320.610.460.36

AL

8.71 E-102.04E-104.37E-103.09E-108.32E-111.55E-101.02E-106.31 E-1 14.79E-1 1&39E-112.51 E-106.76E-1 12.29E-098.13E-101 .OOE-094.37E-101 .OOE-094.47E-1 12.19E-102.34E-103.24E-091 .51 E-091.05E-113.55E-101.26E-104.37E-10

Attachment 13 continuedBCalculated values for field water content.ECe and ion concentrations of the saturated-paste extracts were multiplied by the ratio: saturated paste water content/field water content

pwsat/pwfield

4.239.279.785.74

16.856.985.834.542.344.453.764.543.494.006.038.176.023.508.833.938.394.555.595.424.51

14.76

0 - 0.4-inchcust IDSL-1BSL-3BSL-6BSL-8SL-10SL-12SL-15SL-17SL-19SL-21SL-24SL-26SL-28SL-31SL-33BSL-35BSL-38SL-40SL-42SL-44SL-47SL-49SL-51SL-53SL-55SL-57

ECe45

2864312

680806289

267151

11144

1320276915732147

23832

205179534

pHe7.227.437.327.377.567.477.537.6

7.647.697.4

7.597.087.237.2

7.327.2

7.657.427.417.037.147.867.35

7.57.32

Ca K Mg Na HC03 SO4 Cl Si ALmmol/L

77.16152.9

168.6990.34286.4

134.35118

73.8147.9

65.6958.2979.3756.7

73.06104

175.6591.7645.53

128.0194.27

21 1 .7783.12

100.5582.73

81.2254.55

47.57286.81

7.531.49

235.6917.8716.3742.97

74.147.83

0.9839.46

1.782.047.72

22.963.85

143.31.59

14.0627.84

4.6585.75

4.1830

7.53

107.84545.1264.359.44

970.22157.9174.29

151.34701.71569.7121.66

246.2624.4136.2369.45

12122.26

178.6414.5274.32

531.3159.96

263.1237.95

159.5930.32

292.292099.13

148.846.25

4651 .27427.84324.27513.423353.8

1301.128.16

942.5612.9167.8960.29

419.1117.03

537.497.68

286.911834.23182.19

1571.4423.6

662.9825.68

11.1634.1

39.127.8

68.7421.5

19.5811.9913.4618.179.33

16.696.988.97

13.0233.9916.1342.0221.8914.7727.5113.1246.0319.5319.1349.58

168.73936.12219.53105.52

1691.33204.55

130.8192.59893.23663.6968.01

342.1976.1579.88

124.0621 1 .42105.06377.79143.13101.65426.23109.35461.56115.01225.05276.05

361 .922208.3209.27

5.164240.71694.45460.85555.11

2793.161111.1

36.1889.7320.94

141.31168.8

678.9226.48

432.857.95

481 .582361 .77252.33

1397.7640.69

741.1111.81

3.021.654.894.3

4.213.743.331.3

0.170.8

2.281.462.622.293.884.674.731.885.043.09

1.82.61.8

3.292.095.27

8.71 E-102.04E-104.37E-103.09E-108.32E-111.55E-101.02E-106.31 E-114.79E-1 13.39E-1 12.51 E-106.76E-1 12.29E-098.13E-101 .OOE-094.37E-101. OOE-094.47E-1 12.19E-102.34E-103.24E-091.51E-091.05E-113.55E-101.26E-104.37E-10

Attachment 14. Calcite content in the surface crust ( 0 to 0.4-in) and in the 3 to 6 inch depth interval.

Location Depthinch

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

-.4

Gust ID

SL-1B ..

SL-3B

SL-6B

SL-8

SL-10

SL-12

SL-15 1

SL-17

SL-19

SL-21

SL-24

SL-26

SL-28

SL-31

SL-33B

SL-35B

SL-38

SL-40

SL-42

SL-44

SL-47

SL-49

SL-51

SL-53

SL-55

SL-57average

CaCOS%

25

29

24

26

30

27

27

27

23

22

22

24

16

25

30

34

24

22

25

24

30

27

27

27

25

3026

Depthinch

.8

.6

.4

.2

.1

.4

.0

.0

.7

.2

.3

.6

.8

.2

.3

.3

.8

.0

.3

.0

.3

.4

.6

.7

.0

.4

.2

3-

3-

3-

3-

3 -

3-

3 -

3 -

3-

3-

3-

3-

3-

3-

3-

3 -

3-

3-

3-

3-

3-

3-

3-

3 -

3-

3-

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

6

Gust ID

SL-2B

SL-5B

SL-7B

SL-9

SL-11

SL-13

SL-16

SL-18

SL-20

SL-22

SL-25

SL-27

SL-30

SL-32

SL-34B

SL36B

SL-39

SL-41

SL-43

SL-45

SL-48

SL-50

SL-52

SL-54

SL-56

SL-58average

CaCOS%

24

25

24

20

34

27

.4

.5

.4

.7

.2

.7

24.4

20.7

27.0

23

27

22

.5

.5

.9

27.1

26

29

27

.5

.3

.0

22.4

24

27

24

30

23

.1

.5

.1

.9

.8

27.0

20.4

27.3

2225

.6

.5

Attachment 15

Objective 3bElectrical conductivity of the saturated-paste extract (ECe) and concentrations of elements in the surface crust (0 -0.4-inch)and the underlying soil (3 - 6-inch) - used to assess impacts of evapoconcentration on salt content of the surfacecrust.

ion

11

22

33

44

55

66

77

88

99

1010

Depthinch0- .43 - 6

03

03

03

03

03

03

03

03

03

-.4-6

-.4-6

-.4-6

-.4-6

-.4-6

-.4-6

-.4-6

-.4-6

-.4-6

cust ID

SL-1BSL-2B

SL-3BSL-5B

SL-6BSL-7B

SL-8SL-9

SL-10SL-11

SL-12SL-13

SL-15SL-16

SL-17SL-18

SL-19SL-20

SL-21SL-22

ECedS/m

10.63.8

30.87.6

4.45,7

2,12.1

40.47.4

11.412.6

10.66.5

19.69.7

114.325.8

33.811.0

K

11.33.6

31.08.4

0.82:3

0.30.5

14.03.8

2.63.1

2.82.8

9.510.7

31.76.7

10.73.6

Mg

51.014.8

117.724.7

13.224.7

3.33.3

115.242.8

45.353.5

25.523.9

66.649.4

600.699.6

255.965.0

Nammolc/L

69.110.0

226.538.7

15.224.8

1.10.9

276.157.8

61.373.5

55.736.5

113.067.4

1435.2242.2

292.282.2

SO4

79.848.0

202.066.7

44.961,7!

36.8'32.4

200.884.2

58.659.2

44.961.1

84.873.6

764.5192.7

298.1111.0

Cl

85.610.2

238.333.0

21.417.0

0.90.4

251 .751.8

99.5106.8

79.131.0

122.293.4

1195.3187.8

249.564.1

InECe Ln(K+1)

2.365 2.5061.340 1.522

3.4282.031

1.4701.746

0.7610.742

3.6982.007

2.4332.536

2.3611.870

2.9772.273

4.7393.252

3.5212.394

3.4642.245

0.5711.194

, : i -•

0.2310.412

2.7071.577

1.2701.404

1.3381.338

2.3482.463

3.4882.035

2.4631.522

Ln Mg

3.9322.695

4.7683.206

2.5773.206

1.1911.191

4.7473.756

3.8123.979

3.2393.172

4.1993.899

6.3984.601

5.5454.174

LnNa

4.2362.303

5.4233.656

2.723'3.210

0.086-0.139

5.6214.058

4.1164.297

4.0193.598

4.7284.211

7.2695.490

5.6774.409

LnSO4 Ln(CI+1)

4.380 4.4613.872 2.416

5.3084.201

3.8044.123

3.6053.479

5.3024.433

4.0714.082

3.8044.113

4.4404.298

6.6395.261

5.6974.709

5.4783.526

3.1092.890

0.6420.336

5.5323.967

4.6104.680

4.3833.466

4.8144.548

7.0875.241

5.5234.176

Attachment 15 continued

1111

1212

1313

1414

1515

1616

1717

1818

1919

2020

2121

2222

0-3-

0-3-

0-3-

0-3-

0-3 -

0-3-

0-3-

0-3-

0-3-

0 -3-

0-3-

0-3-

.46

.46

.46

.46

.46

.46

.46

.46

.46

.46

.46

.46

SL-24SL-25

SL-26SL-27

SL-28SL-30

SL-31SL-32

SL-33BSL-34B

SL-35BSL36B

SL-38SL-39

SL-40SL-41

SL-42SL-43

SL-44SL-45

SL-47SL-48

SL-49SL-50

3.02.6

31.86.8

3.72.8

5.13.3

4.53.2

8.59.2

2.62.4

20.83.0

2.42.6

11.94.1

28.39.7

7.12.5

0.30.8

8.72.6

0.51.0

0.50.9

1.31.0

2.82.8

0.60.4

40.94.1

0.20.5

3.61.3

3.33.8

1.00.8

11.59.9

108.641.1

14.09.1

18.111.5

23.013.2

29.628.0

7.44.1

102.012.3

3.33.3

37.814.0

126.745.3

26.38.2

2.29.6

207.846.5

3.71.1

17.07.8

10.04.4

51.348.3

2.81.7

153.54.8

0.90.5

73.017.4

218.788.7

40.03.9

36.234.9

150.973.6

43.740.5

39.942.4

41.247.4

51.852.4

34.934.9

215.846.1

32.429.3

51.846.8

101.696.7

48.039.3

9.613.7

196.242.2

6.00.6

35.36.6

28.03.9

83.172.1

4.41.4

123.61.4

0.90.8

122.616.3

281.670.9

55.43.6

1.0990.940

3.4591.921

1.2951.015

1.6211.203

1.5001.172

2.1352.222

0.9440.867

3.0361.112

0.8710.963

2.4781.399

3.3442.273

1.9630.920

0.2310.571

2.2721.270

0.4120.703

0.4120.652

0.8240.693

1.3381.338

0.4950.322

3.7361.627

0.1660.378

1.5220.824

1.4631.577

0.7030.571

2.4442.290

4.6883.717

2.6382.203

2.8962.444

3.1372.577

3.3883.331

2.0011.413

4.6252.513

1.1911.191

3.6332.638

4.8423.812

3.2712.108

0.7752.259

5.3373.840

1.3080.086

2.8312.058

2.3031.470

3.9383.877

1.0400.554

5.0341.564

-0.139-0.734

4.2912.856

5.3884.485

3.6891.364

3.5883.553

5.0174.298

3.7763.702

3.6873.747

3.7173.858

3.9473.959

3.5533.553

5.3743.832

3.4793.378

3.9473.845

4.6214.571

3.8723.671

2.3612.688

5.2843.766

1.9460.470

3.5922.028

3.3671.589

4.4324.292

1.6860.875

4.8250.875

0.6420.571

4.8172.851

5.6444.275

4.0321.526

Attachment 15 continued

2323

2424

2525

2626

0-3 -

0-3-

0-3-

0-3-

.46

.46

.46

.46

SL-51SL-52

SL-53SL-54

SL-55SL-56

SL-57SL-58

36.714.8

3.12.7

21.04.8

2.32.5

15.46.1

0.81.3

6.71.5

0.50.4

94.251.8

14.09.1

70.814.4

4.1' 4.1

281.3113.0

4.43.5

147.018.3

1.72.0

165.2108.5

42.439.3

99.859.9

37.433.7

250.295.0

7.51.8

164.311.8

0.81.5

3.6022.693

1.1441.004

3.0421.575

0.8420.916

2.7941.966

0.5710.824

2.0350.932

0.4120.322

4.5453.948

2.6382.203

4.2592.667

1.4131.413

5.6394.728

1.4701.247

4.9902.905

0.5540.673

5.1074.687

3.7473.671

4.6034.092

3.6223.517

5.5264.564

2.1401.030

5.1082.550

0.5880.916

Attachment 16.

K/T GeoServicesIncorporated

v n-j-j- ^X-ray DiffractionMineralogy... r „with Impact

www.ktgeo.com

(940) 597-9076fax (940) 387-9980

4993 Kiowa TrailArgyle TX 76226

July 2, 2005

Jim RaweSAIC(859)331-7197rawej@fuse.net

Subject:Sample ID:K/T File No.:

Dear Jim,

X-ray Diffraction AnalysesSL-10, SL-19, SL-26Z05166 :

This report presents the results of bulk (whole rock) X-ray diffraction (XRD) analysis performedon 3 samples. This analysis is performed to provide mineralogy of the samples.

Enclosed find the tabular XRD data (weight percentage), the X-ray diffraction traces and adetailed description of sample preparation and analytical procedures. For your convenience, Ihave sent a copy of this report via e-mail.

Unused portions of the sample will be returned upon request. If you have any questionsconcerning these results or if you need anything else please contact me at (940) 597-9076.Thank you for using K/T GeoServices to perform your X-ray diffraction analyses and I lookforward to working with you again in the future.

Sincerely,

James P. Talbot, P.O.

NOTICE: The results and interpretations presented in this report are based on materials and information supplied by the client and represent thejudgment of K/T GeoServices, Inc. This report is intended for the client's exclusive and confidential use, and any user of this report agrees thatK/T GeoServices, Inc. and its employees assume no responsibility and make no warranties or representation as to the utility of this report for anyreason. K/T GeoServices, Inc. and its employees shall not be liable for any loss or damage, regardless of cause, resulting from the use of anyinformation contained herein. "~'7"f•-""'

K/T GeoServices Report Z05166 Page 1 of 7 July 2, 2005

Attachment 16.X-ray Diffraction Data

Sample IDSL-10 SL-19 SL-26 Mineral

nd nd nd Anhydritend nd nd Aragonitend nd nd CaCO3xH2O

66% 44% 24% Calcitend nd nd Chalcedonynd nd nd Chrysotilem m m Cristobalitend nd nd Dolomite (disordered'1% 7% 9% Dolomite (ordered)1% 25% 14% Gypsumnd nd nd Huntitend nd nd Magnesite

21% 21% 43% Quartzm nd nd Sepiolitem nd nd Sepiolite (A)nd nd nd SiO2 (am,gel)nd nd nd SiO2 (am,ppt)nd nd nd Vaterite4% 0% 3% K-Feldspar2% 0% 1% Plagioclase Feldspar5% 3% 5% Total Clay Minerals

m = may be presentnd = not detected

Weight percentages in this data table are very rough estimates and have large relative errors.Amorphous minerals cannot be detected by XRD methods.

See page 3 for a discussion of X-ray diffraction terminology and limitations.Sample preparation and analytical procedures are on page 4X-ray diffraction traces are on pages 5 to 7.

K/T GeoServices Report Z05166 Page 2 of 7 July 2,2005

Attachment 16.Discussion of Terminology and Limitations

Weight percentage data from X-ray diffraction methods are considered semi-quantitative. Thereare many factors affecting the results.

XRD methods can quantify crystalline material only. Organic non-crystalline material in largeconcentrations can be detected but not quantified. Therefore, any organic and/or non-crystallinematerial is not included in the accompanying results.

Detection limits for XRD are high compared to other analytical methods. These are on the orderof 1% to 5% and this detection limit differs for each mineral.

Mineral standards used to determine calibration factors are often different from the actualminerals analyzed. Minerals such as feldspars that undergo solid solution are especiallyproblematic. Clay minerals are problematic for this same reason. Clay minerals also have awide range of crystallinities (poorly crystallized to well crystallized) which may compound thisproblem.

With this method the data always sums to 100%. This means that the percentages reported foreach mineral are dependent upon the percentages reported for the other minerals. If one mineralis underestimated the others will be overestimated. Also, if one or more minerals are present butnot detected then the percentages of the minerals that are detected will be overestimated.

Any or all of these factors may affect the percentages presented in this report.

Data are formatted as weight percent, but are actually calculated as weight fractions. Therefore,slight rounding errors may be observed in the formatted data.

K/T GeoServices Report Z05166 Page 3 of 7 July 2,2005

Attachment 16.K/T GeoServices, Inc.

Qualitative XRD AnalysisSample Preparation and Analytical Procedures

Sample PreparationA sample submitted for qualitative XRD analysis is gently ground in an agate mortar and pestle,if necessary. The resulting powder is then pressure-packed into an aluminum sample holder toproduce random whole rock mount.

Analytical ProceduresXRD analyses of the sample is performed utilizing a Rigaku automated powder diffractometerequipped with a copper source (40kV, 35mA) and a scintillation detector. The whole-rocksample is analyzed over an angular range of 2 - 65 degrees 2 theta at a scan rate of onedegree/minute.

Phases are identified using the JCPDS powder diffraction file.

K/T GeoServices Report Z05166 Page 4 of 7 July 2,2005

Attachment 16.Sample ID SL-10

Bulk X-ray Diffraction Trace

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K/T GeoServices Report Z05166 Page 5 of7 July 2, 2005

Attachment 16.

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K/T GeoServices Report Z05166 Page 6 of7 July 2, 2005

Attachment 16.Sample ID SL-26

Bulk X-ray Diffraction Trace

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K/T GeoServices Report Z05166 Page 7 of7 July 2, 2005