Fact Sheet | May 2009
Frequently Asked Questions about Split Sampling in
Collinsville Related to the Collinsville Soil Program
Q: What is a split sample?
A: A split sample is one of two equivalent portions of the same sample that is analyzed separately, typically by different parties
using different laboratories, and is used to
spot check the accuracy of data. Split samples
can also provide a measure of the sample
variability and a measure of analytical errors.
Q: Why is DEQ taking split samples?
A: Field oversight and split sampling are
routinely used by DEQ to make sure the data
collected is representative and accurate. The
DEQ is monitoring the residential sampling in
Collinsville to verify that it follows the approved sampling plan. During field oversight
DEQ randomly selects an area or areas to
collect a split sample.
Q: How do you evaluate data from split
samples?
A: The data DEQ gets from its lab is compared to results that Cyprus Amax Minerals
gets from its lab. While the results generally will not be identical, they will be similar.
Some variability between sample results is
normal and expected. All sample results are
compared to the established cleanup numbers
to determine if cleanup is necessary.
Q: Will DEQ take split samples on my
property?
A: DEQ randomly selects split sample locations. This means that not every home will
have a DEQ split sample result. Use of random sampling allows the DEQ to spot check
work done by Cyprus Amax Minerals.
Q: How does DEQ know that Cyprus
Amax Minerals’s data is good?
A: Data quality is key in any site investigation. It begins in the planning stages and is
carried throughout the project. Many levels of
control are used to guarantee confidence in
the data. Steps are taken in the field, in the lab,
and in the reporting and evaluation of data to
make sure the data is accurate.
Before the start of an investigation, DEQ
reviews and approves the work plan, which
contain protocols for data quality contained in
a document called the Quality Assurance Project Plan (QAPP). The DEQ makes sure the
correct sampling and analysis procedures are
used in the investigation to reduce or eliminate the introduction of errors. A QAPP is
required by the DEQ whenever sampling and
analysis is performed. DEQ routinely monitors projects to ensure they are implemented
as planned. Split sampling allows random spot
checks to verify data quality.
This publication is issued by the Department of Environmental Quality as authorized by Steve Thompson, Executive Director. Copies have been
printed at a cost of $0.053 each. Copies have been deposited with the Publications Clearinghouse of the Oklahoma Department of Libraries.
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