Initiation of a Sediment Laboratory Quality Assurance Project
To: "A - Division Chief and Staff",
"B - Branch Chiefs and Offices",
"DC - All District Chiefs"
cc: "File WRD Archive Reston, VA ",
"Annette L Ledford, Clerk Typist, Reston, VA "
Subject: Office of Surface Water Technical Memorandum No. 96.11
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Date: Fri, 30 Aug 1996 13:24:49 -0400
From: "Annette L Ledford, Clerk Typist, Reston, VA "
In Reply Refer To: August 28, 1996
Mail Stop 415
OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 96.11
SUBJECT: Initiation of a Sediment Laboratory Quality Assurance
As part of on-going efforts to improve quality-assurance procedures
for data collected by the U.S. Geological Survey (USGS), the Branch
of Technical Development and Quality Systems (BTDQS) has developed a
national framework to objectively quantify bias and precision of
suspended-sediment sample analyses performed by USGS sediment
laboratories, or for the USGS by contract laboratories. With the
support of the Office of Surface Water (OSW), this framework will be
implemented in August 1996 as the Sediment Laboratory Quality
Assurance (SLQA) project. Participation in the SLQA project is
required by all USGS laboratories that analyze sediment samples,
including contract laboratories used by the USGS.
BACKGROUND: OSW Technical Memorandum 91.11 outlines four quality-
assurance requirements for sediment laboratories that analyze samples
for the USGS. One of the requirements is successful participation in
a standard reference-sample program for sediment analysis. Such a
project was operated in pilot mode in 1992 and 1994, and has been
codified into the SLQA project.
DESCRIPTION OF THE SLQA PROJECT: The project is designed as an
interlaboratory-comparison evaluation to provide a measure of bias
and variance of suspended-sediment data produced by sediment
laboratories operated or used by the USGS. The project will produce
quality-assurance statistics on sediment analyses for each
participating laboratory, as well as from a national perspective.
The SLQA Project does not supplant existing quality-control
procedures that are part of each laboratory's routine operation.
LABORATORY ANALYTICAL TIMETABLE: A total of 18 standard reference
sediment samples for use in the project will be prepared and
distributed directly from the BTDQS to participating laboratories via
mailings this month and in late September 1996. Sediment laboratory
analytical results should be returned to the BTDQS within 45 days of
each mailing. A summary of results should be available in the first
quarter, fiscal year (FY) 97.
BTDQS COMPILATION AND REPORTING: Results of suspended-sediment
concentrations, sand/fine splits, and particle-size analyses
completed by sieve/pipet, Sedigraph, and bottom withdrawal methods
will be compiled and evaluated by the BTDQS. A report summarizing
the analytical results will be provided to the participating
laboratories and to the Sediment Action Committee (SAC). The BTDQS
will advise and provide recommendations to the laboratories and the
SAC on appropriate actions, if any, as a result of the project.
COSTS: The Office of Surface Water is providing support for the
preparation and distribution of the standard reference samples in
FY96. Sediment laboratories are expected to analyze the samples free
of charge and provide results to the BTDQS in a timely manner. It is
anticipated that costs associated with the SLQA project will
eventually be incorporated into the normal operating costs of each
sediment laboratory as part of the cost of analyzing each sample,
which would increase analytical costs by about 3 percent. FY96
results will be used to determine how best to direct available
resources for the SLQA project in FY97 and thereafter.
SUMMARY: The SLQA project will benefit the USGS by providing an
objective quality-assurance evaluation of USGS sediment laboratories
and contract laboratories. In addition, the SLQA will provide the
ongoing information needed to verify that sediment data from all
laboratories used by the USGS are comparable. The support of the
USGS laboratories and contract laboratories in providing the timely
data required to fulfill the goals of the project will be greatly
Thomas H. Yorke
Chief, Office of Surface Water
WRD Distribution: A, B, DC