Soil crust sampling & analysis rpt (final)
Transcript of Soil crust sampling & analysis rpt (final)
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 [email protected]
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)[email protected]
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