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


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

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