Comparison of the Suspended-Sediment Splitting Capabilities of the Churn and Cone Splitters
To: "A - Division Chief and Staff",
"B - Branch Chiefs and Offices",
"DC - All District Chiefs",
"CD - All Data Chiefs",
wqspecs@usgs.gov,
"William M Alley, Chief, OGW, Reston, VA" ,
"Mary J Amos, Secretary (OA), Reston, VA" ,
"Velvie E Stockdale, Office Automation Assistant, Reston, VA" ,
"Thomas E Reilly, Hydrologist, Reston, VA" ,
"Hayes F Grubb, RASA Coordinator, OGW, Reston, VA" ,
"Kenneth J Hollett, Asst. Chief, OGW, Reston, VA" ,
"Jilann O Brunett, Data Coordinator, Reston, VA" ,
"Arlen W Harbaugh, Hydrologist, Reston, VA" ,
"James W LaBaugh, Hydrologist, Reston, VA" ,
"John R Gray, Hydrologist, Reston, VA" ,
"Harvey E Jobson, Hydrologist, Reston, VA" ,
"L. Jane Rose, Secretary, Reston, VA" ,
"Annette L Ledford, Clerk Typist, Reston, VA" ,
"Harry F Lins, Hydrologist, Reston, VA" ,
"Robert R Mason Jr., Hydrologist(Engr), Reston, VA" ,
"Alison Barker, Volunteer Hydrologist, Reston, VA" ,
"Thomas H Yorke Jr., Chief, OSW, Reston, VA" ,
"Ernest F Hubbard, Assistant Chief, OSW, Reston, VA" ,
"William H Kirby, Hydrologist (Engr), Reston, VA" ,
owq@usgs.gov
Date: Wed, 14 May 1997 09:51:50 -0400
From: "David A Rickert, Chief, OWQ, Reston, VA"
In Reply Refer To:
Mail Stop 412 May 5, 1997
OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM NO. 97.06
Subject: Comparison of the Suspended-Sediment Splitting Capabilities of
the Churn and Cone Splitters
The Office of Water Quality (OWQ), with advice from the Office of Surface
Water (OSW) and the National Water Quality Assessment (NAWQA) Program,
has conducted a series of laboratory tests on the suspended-sediment
splitting capabilities of the churn and cone devices. The tests were
conducted on prepared samples using monomineralic silica sands of various
controlled concentrations and mean particle sizes in distilled water. The
detailed results of the tests are available via anonymous ftp in a
document entitled "Selected Laboratory Tests of the Whole-Water Sample
Splitting Capabilities of the 14-Liter Churn Splitter and Teflon Cone
Splitter" by Art Horowitz and others.
ftp: srv3rvares.er.usgs.gov/
login: anonymous
password: userid
cd pub/owq/
binary
get OWQ97.06.report/
bye
The major findings of the sample-splitting tests and resultant Division
policies are:
1. At suspended-sediment concentrations <1,000 mg/l and mean particle
size <250 um, the two devices provide sufficiently comparable and
acceptable sample-splitting capabilities for whole-water samples (based
on bias and precision) to enable interchangeable use. A
suspended-sediment concentration of 1,000 mg/L is equivalent to the 93rd
percentile of average suspended-sediment concentrations at 428 U.S.
Geological Survey (USGS) river-monitoring stations for the period
1980-89. Also, for the 1,000 mg/L limit, historical data indicate that
the concentration of sand grains >250 um is likely to be small.
2. At a suspended-sediment concentration of 10,000 mg/L (the next tested
level above 1,000 mg/L), the churn exhibits unacceptable bias and
precision. Thus, the upper suspended-sediment concentration limit for
processing whole-water samples with the churn splitter is set at <1,000
mg/L.
3. At a suspended-sediment concentration of 10,000 mg/L, the cone
splitter still splits samples with acceptable bias and precision.
Performance of the cone is unacceptable at 100,000 mg/L (the next tested
level). Thus, the upper limit for processing whole-water samples with the
cone splitter is set at <10,000 mg/L. This is equivalent to greater than
the 99th percentile of the average suspended-sediment concentrations at
the 428 USGS river-monitoring stations.
Based on these results, Division personnel can use either device for
processing whole-water samples with suspended-sediment concentrations
<1,000 mg/L, and can use the cone splitter for samples with
suspended-sediment concentrations of <10,000 mg/L.
The offices thank Art Horowitz, Tim Hayes, John Gray, Paul Capel, and
Judy Scholz for their major roles in designing, implementing, and
interpreting the splitting device tests. We also thank the
Instrumentation Committee for financially supporting this important
effort.
David A. Rickert
Chief, Office of Water Quality
This memorandum supersedes OWQ Technical Memorandums 76.24-T and 77.01,
and modifies 80.17.
Key words: churn, cone, concentrations, sediment
Distribution: A, B, DC, CD
District Water-Quality Specialists
Office of Ground Water Staff
Office of Surface Water Staff
OWQ Staff
Regional Water Quality Specialists