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The recent discussions on the SPT showed that much attention is paid to the details of reporting. Research on the SPT has shown that the input energy has a very significant influence on the blow count obtained for a given soil resistance. I am curious how engineers approach this issue in different pasts of the world. The ASTM standard D6066-96 appears to sanction the assumption that safety hammers used with two wraps of the rope around the cathead deliver a standard energy of 60% of the available potential energy prior to release of the hammer mass. I have the following questions: (1) What is the practice in your jurisdiction? (2) If an energy is assumed to apply to a given hammer type, what is the basis for that assumption? Is it Skempton (1986) or are there individual research reports to back the practice in your area? (3) How common is energy measurement on site exploration contracts? (4) For those measuring energy, how is it done? The ISSMFE Reference Test Procedure (1988) advocates the use of stress wave energy measurement based on measurement of the Force time history alone, as did the ASTM Standard D4663 which was allowed to lapse in 1998. Is this the approach used? (5) Do you reduce the measured N-value by the factor of between 0.75 to 0.95 for test depths shallower than 10 m as was advocated by Skempton (1986). This was to account for the fact that the input energy appeared to be lower at shallow depths. Your input on any or all of the above questions would be greatly appreciated. ---------------------------------------- John A. Howie, Ph.D., P.Eng. Associate Professor Department of Civil Engineering University of British Columbia 2324 Main Mall Vancouver, B.C. V6T 1Z4 ---------------------------------------- Phone: (604) 822-2877 Fax: (604) 822-6901 E-mail:[log in to unmask]