United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas, NV 89119
Research and Development
Kir EPA Project Summary
EPA/600/SR-93/073 July 1993
An X-Ray Fluorescence
Survey Of Lead Contaminated
Residential Soils in
Leadville, Colorado:
A Case Study
C.A. Kuharic, W.H. Cole, A.K. Singh, and D. Gonzales
Concern over the adverse impacts to
human health due to exposure to lead
has prompted characterization efforts
at numerous sites across the United
States. One of the primary exposure
routes to man is through the ingestion
and inhalation of lead contaminated
soils. This problem can be of concern
at old mining and smelting locations,
such as the California Gulch Super-
fund She.
The California Gulch site is a historic
lead mining and smelting site that was
added to the National Priority List (NPL)
in 1983. During the summer of 1991, at
the request of the Remedial Project
Manager, personnel from the U.S. EPA's
Environmental Monitoring Systems
Laboratory at Las Vegas participated
in a survey that included the design,
collection, and analysis of soil samples
from this site.
The objective of this survey was three
fold: to gather sufficient data that would
permit the use of geostatistics to de-
termine optimal sample size and spac-
ing; to identify geographical distribution
of soil lead levels in specific concen-
tration ranges; and to demonstrate the
ability of field portable X-Ray Fluores-
cence (FPXRF) instrumentation to gen-
erate quantitative data of sufficient and
known quality. Satisfying the objectives
of this survey required the develop-
ment of a sampling and analysis plan
and a quality assurance project plan
that addressed the identification and
quantification of error associated with
the sampling, sample handling, and
analytical methods.
Both field portable and laboratory
XRF instruments were used for the sur-
vey. The three field portable instru-
ments used were X-Met* 880's marketed
by Outokumpu Electronics. For mea-
surement correlation purposes, the
laboratory grade Kevex 770, marketed
by Fisons Instruments was utilized.
The case study details the XRF moni-
toring approach, sample collection,
preparation, and analysis procedures,
and the database management and
Quality Assurance/Quality Control mea-
sures that were implemented for this
survey. This survey demonstrated that
field portable XRF instrumentation can
produce large quantities of acceptable
quality data in a timely, cost-efficient
manner.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Las Vegas, NV, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Leadville is about 100 miles southwest
of Denver. It is situated on the western
slope of the Mosquito Range, just east
and upslope of the Arkansas River, at an
elevation of approximately 10,200 feet.
* Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use.
Printed on Recycled Paper
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Mining activity occurred predominantly on
the eastern side of Leadville, along the
drainages of California, Evans, Stray
Horse, Oregon, Malta and Georgia
Gulches. Mining in this area was traced to
the discovery of placer gold in California
Gulch. During 1874, a heavy mineral that
interfered with the placer gold operations
was identified as silver-bearing lead car-
bonate. Eventually, the mining and pro-
cessing turned from the oxidized,
carbonate ores to the less desirable sul-
fide ores, of lead and zinc.
The dispersion of lead occurred from
natural processes, such as wind and wa-
ter; however, in Leadville, the problem
was exacerbated by human impacts, rang-
ing from smelter stack emissions to slags
that were crushed and spread on icy roads
and used for railroad ballast. Tailings and
mine waste rock were thoroughly mixed
into local soils by over a century of mining
and commercial activities in which these
materials were often used for fill material.
Many homes were built among the waste
rock/tailings piles or immediately adjacent
to them. The use of these mining gener-
ated materials and their close proximity to
human habitation raises a health concern
and a need to identify the concentrations
and the geographical distribution of soil
lead within and in the immediate vicinity of
Leadville.
Survey
Initially, two major issues had to be
addressed. The first issue was to deter-
mine if a single matrix model for the XRF
instruments would be adequate for ana-
lyzing all of the soils within the area to be
surveyed. The second issue, stemming
from access difficulties, involved determin-
ing whether samples collected at the edge
of the public easement of alleyways and
from nearby residential yards were of a
single population.
Assessment of XRF and CLP data ob-
tained from the same samples indicated
that a single matrix model could be used.
Data assessment to determine the exist-
ence of a single soil population was ac-
complished by using the nonparametric
Kolmogorov-Smirnov procedure and the
paired-wise sample t-test. The results of
these tests showed that no significant dif-
ferences existed between alley easements
and yard soils.
The portable X-Met 880 field units were
energy dispersive spectrometers, self-con-
tained, battery powered and microproces-
sor based, weighing 8.5 kg. The surface
analysis probe of these units contained
an Americium-241 and a Curium-244
source and a proportional tube counter
specifically designed for field use. The
Kevex contained a 198 watt, Rh anode,
liquid-cooled X-Ray tube and a cryogeni-
cally cooled lithium drifted silicon solid state
detector.
To achieve the objective of the survey,
a Quality Assurance Project Plan and a
sampling and analysis plan were devel-
oped. The approach identified in these
plans called for the collection and analy-
sis of over 3,700 soil samples. The
samples were collected along transects at
25-foot intervals. At each sampling loca-
tion, a volume of soil six inches in diam-
eter and four inches deep was collected.
To reduce heterogeneity, the sample was
turned onto itself seven times in situ. After
mixing, all samples were containerized,
labeled, and maintained under chain-of-
custody.
Samples were analyzed field moist by
an X-Met 880 field instrument three sepa-
rate times. Each sample was mixed prior
to and between each of the three analy-
ses. Following these initial measurements,
the sample was dried overnight at 100° C.
After drying, the sample was passed
through a 10 mesh sieve onto a 3 x 3 ft
piece of paper where the sample was
rolled onto itself 20 times to reduce het-
erogeneity. After mixing, approximately 6
gm taken in 10-12 subsamples were
placed into a 31 mm diameter polyethyl-
ene X-Ray cell and sealed with 0.2 mil
polypropylene film. The capped sample
was then analyzed by the Kevex and once
again by one of the X-Met 880 field instru-
ments.
Data Assessment
Correlations between the Kevex and the
X-Met 880 measurements were identified
and documented. The correlations be-
tween the instruments were excellent
throughout the survey. Monitoring instru-
ment stability was accomplished by qual-
ity control check samples measured before
and after each block of 10 samples on the
X-Met 880 instruments and 13 samples
on the Kevex instrument.
Documentation of the correlation be-
tween combined X-Met 880 and CLP mea-
surements and between Kevex and CLP
measurements are presented.
Conclusions
The lead concentration data obtained
by field portable XRF instruments on resi-
dential soils in Leadville was optimal for
producing concentration isopleth maps that
depict gross contamination patterns across
the surveyed area. The large number of
samples analyzed minimized errors in es-
timating values at unsampled points, yield-
ing representative depiction of lead
distribution.
The utilization of XRF technology was
instrumental in analyzing large number of
samples over a three month period,
thereby allowing the cost- and time-effec-
tive determination of spatial patterns of
contamination distribution.
The initial assumption that residential
soils in Leadville were of a very similar
matrix with respect to XRF measurements
was verified. The close agreement be-
tween XRF results and randomly chosen
samples analyzed by CLP methods indi-
cate that the single matrix model used
with the X-Met 880 instruments was a
reasonable approach in dealing with a soil
matrix whose initial components were dis-
tinctly different but presumably well mixed
by residential and mining activities over a
long period of time.
.S. GOVERNMENT PRINTING OFFICE: 1994 - 55O-067/80174
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C.A. Kuharic and W.H. Cole are with Lockheed Environmental Systems and
Technologies Company, Las Vegas, NV89119. A.K. Singh and D. Gonzalesare
with the University of Nevada, Las Vegas, Las Vegas, NV89154.
Kenneth W. Brown is the EPA Project Officer (see below).
The complete report, entitled "An X-Ray Fluorescence Survey of Lead Contami-
nated Residential Soils in Leadville, Colorado: A Case Study," (Order No. PB93-
203156/AS; Cost: $35.00; subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Las Vegas, Nevada 89193-3478
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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