PUBLICATIONS--Revision of Open-File Report 91.84, "Streamgaging Cableways," 

In Reply Refer To:                       September 11, 1991
Mail Stop 415


SUBJECT:  PUBLICATIONS--Revision of Open-File Report 91.84, 
                        "Streamgaging Cableways," by 
                        C.R. Wagner.

Computational errors have been discovered in the 
calculations, made by a contracting engineering firm, of the 
anchorage dimensions published in Open-File Report 91.84.  
The errors were corrected and slightly different soil 
characteristic values were used in the recomputations, 
resulting in anchorage dimensions that range from slightly 
smaller to slightly larger than those in table 4 published in 
the open-file report.

As soon as is practical, the Office of Surface Water intends 
to make an additional review of these computations and the 
assumptions on which they were based, as well as other 
technical aspects of the report.  Once this is done, steps 
will be taken to reissue the report.  Later, it will be 
published as a Techniques of Water-Resources Investigations 
manual.  Identification of any other errors and helpful 
criticisms by users would be appreciated prior to 
republication.  Comments concerning Open-File Report 91.84 
should be sent to C. Russell Wagner (CRWAGNER) at Stennis 
Space Center.

In the meantime, it is recommended that the dimensions in the 
revised table 4, which is attached, be used for designing 
anchors.  The soil characteristics on which this new table is 
based are revised from those appearing on page 8 of the open-
file report.  For soil type A, a coefficient of friction of 
0.40 and a bearing capacity of 6,000 lb/sq ft were used; for 
soil type B, a coefficient of friction of 0.35 and bearing 
capacity of 4,000 lb/sq ft.

Although the dimensions shown in the revised table 4 have 
substantial safety factors for unsubmerged conditions at the 
anchors, the margin of safety is appreciably smaller for 
submerged conditions.  Design of cableway anchors is an 
inexact science, particularly when using the broad 
assumptions of a handbook approach.  Therefore, it is 
recommended that cableways be designed such that they will 
not be loaded when the anchors are submerged or the 
surrounding soil is saturated.  If there is no alternative 
and soil characteristics are particularly poor, however, 
consideration might be given to increasing the volume of the 
anchors up to 1.7 times that given in the revised table 4 to 
compensate for the buoyancy of the concrete in water.

Recomputation of the dimensions for support footings and 
other system components have indicated that no significant 
changes in these specifications are needed.

Please ensure that these revisions are received by all 
technical personnel who may have copies of Open-File Report 
91.84.  A revised page 8, as well as table 4 (page 45), is 
attached.  These should be used to replace the existing page 
8 and table 4 of all copies of the open-file report.

                               Charles W. Boning
                               Chief, Office of Surface Water