United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas NC 89193
Research and Development
EPA/600/S8-87/024 Jan. 1988
s>EPA Project Summary
Wet Deposition and Snowpack
Monitoring Operations and
Quality Assurance Manual
D. J. Chaloud, L. R. Todechiney, R. C. Metcalf, and B. C. Hess
The manual (User's Guide) summa-
rized herein presents the quality assur-
ance plan and operations protocols for
a comparative study of snow collection
instruments being conducted on Mt.
Evans. Instruments to be compared
include the Aerochem Metrics Model
301 wet/dry deposition collector, the
Belfort Model 780-5 weighing-rain
gage, and 18 inch-diameter flanged
bulk samplers. In addition, ground
measurements are made to provide a
"ground truth" standard. Primary
project objectives include assessment
of operational reliability, estimation of
inter-instrument and temporal variabil-
ity, comparison of water equivalent and
matrix chemistry between the collec-
tion devices and ground measure-
ments, and recommendation of instru-
ments and sampling intervals for future
high altitude, complex terrain monitor-
ing. The protocols related to quality
assurance, quality control, calibration,
operation, maintenance, processing,
analysis, and data management are
described. The manual is considered to
be of greatest benefit to field operators,
laboratory analysts, and project man-
agers.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing Systems Laboratory. Las Vegas,
NV. to announce key findings of the
research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
Established acidic deposition monitor-
ing networks largely neglect the high
elevation areas of the western United
States. Interest in these areas is growing,
particulary for the Rocky Mountain
region, because of evidence that precip-
itation amount, and possibly total chem-
ical loading, is strongly correlated with
elevation. Most monitoring equipment
and siting criteria were developed for
low-elevation, flat-land sites. Meteorol-
ogy in mountainous terrain is signifi-
cantly more complex, and precipitation
levels are higher than at low-elevation
sites. Research on the suitability of
existing instruments for use at high
altitude is needed before large funding
and personnel resources are committed
to monitoring acidic deposition in moun-
tainous terrain.
The National Atmospheric Deposition
Program (NADP), EPA Region VIII, and
U.S. Forest Service are participating in
an investigation of equipment perfor-
mance at high altitude. The EPA Envi-
ronmental Monitoring Systems Labora-
tory in Las Vegas, Nevada (EMSL-LV),
and the prime contractor for EMSL-LV,
Lockheed Engineering and Management
Services Company, Inc. (Lockheed-
EMSCO), are responsible for equipment
installation, field station operation, and
data interpretation. EMSL-LV and
Lockheed-EMSCO have primary respon-
sibility for construction of the monitoring
platform, installation of equipment,
operator training, snow density/coring
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activities, data verification and interpre-
tation, chemical analyses, and quality
assurance. Instruments to be evaluated
include the Aerochem Metrics Model
301 wet/dry deposition collector, the
Belfort weighing-rain gage, and bulk
samplers. Snow density, snow coring,
and event sampling also are being
undertaken to provide a "ground truth"
comparison. Samplers are to be evalu-
ated in terms of reliability and ease of
operation, catch efficiency, and resultant
sample matrix chemistry. Meteorological
sensors located on the monitoring plat-
form will provide information on the
meteorological environment surround-
ing the collectors.
The selected site is the High Altitude
Laboratory operated by the University of
Denver. The High Altitude Laboratory is
located adjacent to the Mount Evans
highway near Echo Lake, 14 miles south
of Idaho Springs, Colorado. The site
offers several advantages: the terrain is
complex, and the area is subject to large
amounts of precipitation and to high
winds; the site is accessible even in
winter; it has electrical power, and it is
inhabited year-round. A National Oce-
anic and Atmospheric Administration
(NOAA) monitoring station located near
the monitoring platform can provide
additional meteorological information.
This manual details the equipment
operation, chemical analyses, andquality
assurance plan for the wet deposition
and snowpack monitoring project. It is
designed to be of primary benefit to the
station operator, laboratory analysts, and
data analysts. The protocols presented
here may be revised over the course of
the program to reflect necessary changes
and improvements m procedures.
Related documents include an opera-
tions status report which will be deliv-
ered in June 1987 and a final report on
the evaluation results which will be
provided in January 1988.
Project Description
Snowpack and wet deposition moni-
toring on Mount Evans is being con-
ducted to assess the suitability of
selected collection devices to high
altitude, complex terrain situations.
Specific objectives of the project are as
follows:
Inter-instrument sampling variability
for two colocated wet/dry collectors
will be estimated by comparing chem-
istry and water equivalent for weekly
samples.
Inter-instrument sampling variability
for two colocated Belfort weighing-
rain gages will be estimated by
comparing water equivalent for event
and weekly data.
Temporal variability will be estimated
by comparing chemistry and water
equivalent of wet/dry collector event
samples to weekly samples.
Inter-instrument sampling variability
for two colocated bulk samplers will
be estimated by comparing chemistry
and water equivalent for weekly
samples.
A "ground truth standard" for esti-
mating the accuracy of all collection
instruments will be estimated by
comparing sample chemistry to the
chemistry of snowpack cores taken to
snowboards. The comparison will be
made on samples collected after
events.
A "ground truth standard" for esti-
mating the accuracy of all collection
instruments will be provided by com-
paring water equivalent of samples
collected after events and collected
weekly. The comparison will be made
on snow pit density measurements
and on snowboard measurement.
Instruments and sampling intervals
for high altitude, complex terrain
situations will be recommended based
on results of all the above
comparisons.
Operational reliability will be
assessed in qualitative terms of types
of instrument malfunctions, length of
downtime, cause and resolution of
problems, ease of operation, fre-
quency and difficulty of maintenance,
and sample contamination.
The wet/dry collector and Belfort rain
gage are the standard instruments used
by NADP and by other major monitoring
and research networks. The Belfort
gages are unshielded. The bulk sampler
design is identical to that used by the
United States Geological Survey (USGS)
in snow studies. Supplemental instru-
mentation includes Science Associates
Models 424-1 and 424-2 wind speed/
wind direction sensors and a data
acquisition system (DAS) composed of an
IBM at personal computer and Metrobyte
logic boards. Snow coring equipment and
the Taylor-LaChapelle snow-density kits
used are manufactured by Hydro-Tech.I
Snowboards are fabricated by Lockheed-
EMSCO of polyurethane-coated
plywood.
The collection devices and meteorolog-
ical sensors are mounted on a 20-foot
diameter octagonal wooden platform
erected on a southeast-facing slope at
the maximum expected snowpack height
(19 feet at the point closest to the
ground). Cables connect the sensors to
the DAS which is located approximately
275 feet distant in a heated building. The
platform is accessed by steps located on
the uphill (NNE) side. The closest tree
tops subtend an angle of 47° ± 3°. The
nearest of several buildings is located 28
feet NNW of the platform. A fireplace in
one of these buildfngs is' a possible
source of contamination; however, the
building is more than 500 feet away and
is shielded by other buildings and by
trees.
The monitoring equipment and DAS
are checked daily by an on-site operator.
In addition, a Lockheed-EMSCO scientist
visits the site at least once a month.
During most of the study, samples are
collected from two wet/dry collectors
and two bulk samplers on a weekly basis
or more frequently as required by event
loading. Samples are collected from the {
third wet/dry collector daily. Snowboard
cores and snow pit density measure-
ments are taken weekly. During a 30-
day period, two wet/dry collectors are
operated on a daily basis, and the third
is operated on a weekly basis. Snow
cores and snow pit density measure-
ments are taken daily as well as weekly
during this same 30-day period.
No analyses are performed in the field.
On a weekly basis, all samples are
shipped frozen to Lockheed-EMSCO in
Las Vegas, Nevada, where water equiv-
alents are determined and where melted
samples are processed. Processing
includes pH and specific conductance
measurements, which are completed
immediately after melting, and filtration
and preservation of aliquots for subse-
quent analysis. Analyses for chloride and
ammonium are completed approximately
every two weeks; analyses for metal
cations, nitrate, and sulfate are com-
pleted every four weeks. All analyses are
completed within recommended holding
times for the chemical variable of interest
and preservation treatment used.
Data from the field, processing labor-
atory, and analytical laboratory are
compiled into a single database; because
of the small size of the database, an IBM- (
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PC is used for data compilation. Quality
control sample data are used to verify
the data; data of poor or unknown quality
are deleted.
Statistical tests, including paired t-
tests, %RSD, and means, are employed
to quantify the project objectives. Other
interpretative schemes may be deve-
loped dependent upon the initial intra-
and inter-comparison results.
Quality Assurance Plan
The Quality Assurance (QA) policy of
EPA requires that every monitoring and
measurement project have a written and
approved QA project plan. This require-
ment applies to all environmental mon-
itoring and measurement efforts autho-
rized or supported by EPA through
regulations, grants, contracts, or other
formal means. The QA project plan
should specify the policies, organization,
objectives, functional activities, and
specific quality control (QC) procedures
designed to achieve the data quality goals
of the project. As used herein, QC is the
specific procedures and checks used to
provide a quality product, while QA is the
overall system used to ensure that the
QC system is performing. All project
personnel should be familiar with the
policies and objectives outlined in the
operations and QA plan to ensure proper
interactions among the field operations,
laboratory operations, and data
management.
Quality Assurance Objectives
QA objectives are defined in terms of
percision, accuracy, completeness,
representativeness, and comparability.
Precision and Accuracy
The QA objectives' fbr precision and
accuracy of the parameters being mea-
sured are given in the manual. Precision,
defined as the mutual agreement among
individual measurements of the same
property, is expressed in terms of percent
relative standard deviation (%RSD).
Precision is calculated from results of
duplicate analyses and repetitive ana-
lyses of audit samples and quality control
check solutions. Accuracy is the degree
of agreement of a measurement with an
accepted or true value. It is expressed
as percent bias and is determined from
the difference between recorded mea-
surements and accepted true values of
audit samples, quality control check
solutions, and calibration standards.
An additional estimate of precision is
provided by the two colocated wet/dry
collectors, Belfort rain gages, and bulk
samplers. It is common practice in many
studies to designate one unit as the
primary or routine sampler and the other
as a secondary or duplicate sampler. This
practice, in effect, designates samples
from the secondary unit as QC samples.
Because one of the project objectives
is estimation of inter-instrument sam-
pling variability (i.e., quantification of
precision limits), units used inthis project
will not receive primary and secondary
designations. Consequently, a field
duplicate is not included as one of the
QC samples described below. Analysis
of the data on colocated samplers is
included in the data interpretation
scheme, as discussed in the manual.
Field Operations
The equipment installed at the mon-
itoring site includes wet/dry collectors,
Belfort rain gages, bulk samplers, wind
speed and wind direction sensors and a
data acquisition system (DAS). All of
these, with the exception of the DAS, are
mounted on the raised sampling plat-
form. Additional measurements are
taken on the ground within a clearing.
Snowboards provide a base for core
samples which are collected on an event
and weekly basis. Density measure-
ments are performed in a snow pit.
Responsibilities of the site operator
include sample collection, handling, and
shipment; instrument calibration, main-
tenance, and quality control checks;
equipment trouble-shooting and repair;
and documentation of all field activities.
The following sections detail each of
these aspects of field operations; ground-
level measurements are treated in a
separate section of the manual.
Analytical Operations
All processing and analytical activities
are performed by Lockheed-EMSCO in
facilities provided by EPA EMSL-LV.
Processing operations, including water
equivalent determination, aliquot prep-
aration, specific conductance and pH
measurements, and field operations
support are initiated immediately upon
receipt of samples and are concluded
within 48 hours of receipt of frozen
samples. Every two weeks, the aliquots
that have been prepared and accumu-
lated for chloride and ammonium deter-
minators are analyzed; every four weeks
the accumulated aliquots for cations (Na,
K, Ca, and Mg) and nitrate and sulfate
determinations are analyzed. The accum-
ulated aliquots that are analyzed at one
time are considered a unique batch.
Data Management
Most data for this program are provided
on floppy disk. A limited amount of data
must be manually entered (e.g., Belfort
rain gage data). Hand-entered data are
reviewed for transcription accuracy.
Evaluation of data quality is described in
the manual. Following this evaluation,
data of poor or unknown quality are
removed from the data base. Operator
records are reviewed, and data corres-
ponding to calibrations, quality control
checks, maintenance activities, or mal-
functions are removed.
The remaining verified data are ana-
lyzed and interpreted in accordance with
the project objectives. Inter-instrument
comparisons are made for instruments
of the same model operating over the
same sampling interval. These include
the two Belfort rain gages, the two bulk
samplers, duplicate weekly and daily
snow cores, paired weekly wet/dry
collectors, and paired daily wet/dry
collectors. Comparisons are made of the
water equivalent and chemistry results.
Specific comparisons include computa-
tion of means, range, %RSD, and paired
t-tests.
Comparisons between different instru-
ment models employ statistical tests
similar to those described above. All
instruments operating over the same
sampling interval are intercompared with
intercomparison being based on water
equivalent and chemistry results. In
addition, comparisons are made of same
model and different model instruments
operating over different sampling inter-
vals. This comparison of daily and weekly
samples is made possible by integration
of daily samples to create a "synthetic"
weekly sample. Graphics are also used
to illustrate temporal variability results.
The water equivalent and chemistry
results of each instrument are also
compared to ground truth measure-
ments. The ground truth measurements
include snow pit density measurements
(water equivalent only) and snow cores
(chemistry and water equivalent). To
make these comparisons, the inter-
instrument and spatial variability must
be quantified; comparisons between.
instruments and ground truth measure-
ments are generally made on means
rather than on individual sample data.
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Operational reliability is assessed on
the basis of field documentation and data
quality. Statistical analyses, comparison
to ground truth, and operational reliabil-
ity are all considered in the evaluation
of recommended instruments and sam-
pling intervals; this is the substance of
the final project objective.
D. J. Chaloud, L. R. Todechiney, R. C. Metcalf, and B. C. Hess are with Lockheed
Engineering and Management Services Co., Inc., Las Vegas, NV 89114.
W. L. Kinney is the EPA Project Officer (see below).
The complete report entitled "Wet Deposition and Snowpack Monitoring
Operations and Quality Assurance Manual," (Order No. PB 87-212 817/
AS; Cost: $18.95, 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
P.O. Box 93478
U.S. Environmental Protection Agency
Las Vegas. NV 89193
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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