Guidelines from the 1998 Sediment Laboratory Chiefs Workshop
Date: Fri, 29 Jan 1999 11:58:52 -0500
From: Jane Rose
To: "A - Division Chief and Staff",
"B - Branch Chiefs and Offices",
"FO - State, District, Subdistrict and other Field Offices",
"PO - Project Offices"
CC: " WRD Archive File, ",
"L. Jane Rose, Secretary, Reston, VA "
Subject: OSW Technical Memorandum No. 99.04
In Reply Refer To:
Mail Stop 415 January 25, 1999
OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 99.04
SUBJECT: Guidelines from the 1998 Sediment Laboratory Chiefs Workshop
This memorandum reflects the policy of the Office of Surface Water
(OSW) based on recommendations from the third Sediment Laboratory
Chiefs Workshop held in Baton Rouge on March 23-26. A summary of the
workshop, which includes revised guidelines for selected laboratory
methods, can be found at:
Sediment Laboratory Environmental Data System (SLEDS):
Effective immediately, SLEDS is the Water Resources Division's sole
official sediment laboratory data- management software package. SLEDS
will require support totaling about $20K in FY1999 and about $5K
thereafter. The OSW will provide the requisite FY1999 support funds.
SLEDS support in subsequent years will be provided by sediment
laboratories used by the Division. The amount each laboratory will be
required to pay for SLEDS support in FY2000 will be determined later
Criteria for "warning" and "control" limits for sediment laboratory
OSW Technical Memorandum 98.05 requires publication of criteria for
evaluating the performance of participating sediment laboratories. To
this end, statistically based "control" and "warning" limits for
laboratory performance have been adopted. A laboratory that provides
two or more results for a method outside of prescribed "control"
limits in consecutive cycles of the single-blind reference
sediment-sample project becomes a candidate for follow-up evaluations.
A laboratory that is subsequently deemed to be "out of control" for a
method may be barred from providing data produced by that method.
"Control" and "warning" limits for quality-control data are often set
as multiples of the standard deviation, a parametrically based
statistic. The presence of extreme outliers and non-normally
distributed data characteristic of quality-control testing make the
use of nonparametric statistical methods advantageous over traditional
parametric-based methods. The F-pseudosigma is a nonparametric
statistic analogous to the standard deviation. Because the
F-pseudosigma is calculated using the 25th and 75th percentiles in a
data set, it is resistant to the effect of extreme outliers.
Laboratory data are considered to have reached a "warning"
interval for a method if a significant percentage of its analytical
results range from +/- (2 to 3) F-pseudosigma. Results for a method
exceeding +/- 3 F-pseudosigma are considered to be "out of
Publication of statistics from the Sediment Laboratory Quality Assurance
OSW Technical Memorandum 98.05 stipulates that all quality-control
data obtained through the Sediment Laboratory Quality Assurance
Program will be published with individual laboratories identified by
code. This policy is in effect when data from a participating
laboratory are insufficient to determine bias or trends.
A national statistical summary of quality-control results that
identifies the participating laboratories will be made available when
the quality-control data set is considered statistically significant.
The national statistical summary will identify bias and trends in the
quality-control data set. Participation in three full cycles of the
single-blind reference sediment-sample project will be sufficient to
provide statistically significant results from a laboratory.
Travel costs for certified sediment laboratory reviewer:
OSW Technical Memorandum 98.05 states that a District being reviewed
is responsible for paying the certified laboratory reviewer's travel
costs for review of its sediment laboratory. The travel costs will be
charged directly to the District. Certified sediment laboratory
reviewer travel costs for review of contract laboratories will be
charged to the contracting District.
An effort is being made to increase the pool of certified sediment
laboratory reviewers. To this end, the OSW supported three certified
sediment laboratory reviewers-in-training since July 1998, and intends
to continue this support based on the availability of funds.
Revised sediment laboratory guidelines:
The operation of sediment laboratories used by the Division are
principally guided by the contents of four publications. They are:
-- Laboratory Theory and Methods for Sediment Analyses: Techniques of
Water Resources Investigations Book 5, Chapter C1
-- Quality-Assurance Plan for the Analysis of Fluvial Sediment by
Laboratories of the U.S. Geological Survey: Open-File Report 91-467
-- Quality Assurance Guidelines for the Analysis of Sediment
Concentration by U.S. Geological Survey Sediment Laboratories:
Open-File Report 92-33
-- Quality Assurance Plan for the Collection and Processing of
Sediment Data by the U.S. Geological Survey, Water Resources Division:
Open-File Report 92-499
Appendix A of the summary of the 1998 Sediment Laboratory Chiefs
Workshop augments and in some cases supersedes quality assurance and
quality control practices for sediment data described in these three
reports. These practices should be implemented by all sediment
laboratories used by the Division, and referenced in sediment
laboratory quality-assurance plans.
Documenting non-standard techniques and equipment:
Chiefs of sediment laboratories used by the Division should review
Techniques of Water Resources Investigations Book 5, Chapter C1;
Open-File Reports 91-467, 92-33, and 92-499; and the appendix from the
1998 Sediment Laboratory Chiefs Workshop. Any laboratory technique or
equipment not identified in this literature should be summarized in a
memorandum to the OSW and the Office of Water Quality's Branch of
Quality Systems (BQS). The memorandum should include results from any
quality-control tests associated with the non-standard techniques or
equipment. The OSW and the BQS will determine if the non-standard
techniques or methods are acceptable for providing data to the
Keywords: Sediment laboratories, sediment, quality assurance
This memorandum compliments the following:
Office of Surface Water Technical Memorandum 98.05
Office of Surface Water Technical Memorandum 96.11
Techniques of Water Resources Investigations Book 5, Chapter C1
Open-File Report 91-467
Open-File Report 92-33
Open-File Report 92-499
Thomas H. Yorke
Chief, Office of Surface Water
WRD Distribution: A, B, FO, PO