PROGRAMS AND PLANS: Quality-assurance program for sediment laborator1es


In Reply Refer To:                                 June 2, 1980
EGS-Mail Stop 412	


QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 80.16

Subject: PROGRAMS AND PLANS: Quality-assurance program for 
                             sediment laborator1es

The Quality of Water Branch is initiating a quality-assurance 
program for sediment laboratories. As a first step in this 
program, test samples for particle-size analysis of suspended 
sediment finer than 0.062 mm have been prepared for use with 
either the pipet or the bottom-withdrawal-tube method of analysis.

Each test sample has about 4 grams of natural river sediment, 
100 percent finer than 0.062 mm, concentrated in a 40 mL capacity 
amber glass bottle. A single test sample can be used for a single 
pipet or bottom-withdrawal-tube analysis (4000 mg/L), or it can be 
split and used for two analyses (2000 mg/L each).

Each district having a sediment laboratory that uses either pipet 
or bottom-withdrawal-tube methods for determining particle-size 
distribution of sediment is requested to obtain and analyze three 
test samples as soon as possible. Test samples should be requested 
from Mr. Leroy Schroder, Quality-Assurance Support Project, MS 
407, Lakewood, Colorado 80225.

It will not be possible to treat this initial set of test samples 
as blind samples in the sediment laboratories. However, the 
analyst should be asked to treat each 40 mL bottle of sediment as 
a routine sample. The sediment should be chemically dispersed and 
analyzed in distilled water. We wish not only to develop an 
intercomparison of analytical results but also to determine how 
well the preservation technique used (refrigeration and amber 
bottles) works. For the latter purpose, we will rely heavily on 
detailed comments by the analysts. If the method used to prepare 
and preserve these test samples gives good results, we plan to 
expand the program to include other sizes of materials.

We are requesting that your laboratory complete the analyses 
within 30 days after receiving the samples and send the results of 
analyses plus any pertinent comments regarding the preservation of 
the sample or the test program in general to Mr. Schroder as soon 
as possible. We will appreciate your sending copies of all 
correspondence, including results of analyses, to the Quality of 
Water Branch also. Thank you for your cooperation in this 
important aspect of quality control in the WRD.




                               R. J. Pickering

WRD Distribution: A, FO-LS

This memorandum does not supersede any previous memorandum.