Document 4ad7qBXgNk7m8j6RK3jq3M3EG

Air Mail May 13, 1959 Mr. Wil Hancock Ethyl Corporation 901 Russ Building 235 Montgomery Street San Francisco 4, California Dear Wil; Thanks very much for your letter of May 8 in which you review some of the points that I discussed with John Koehnle during our recent telephone conversation. John conveyed my thoughts very well and your listing of items and comments covers the subject matter of our discussion very well.- Thanks also for indicating the volumes which will be used in sampling Phase 1 and 2. These volumes will be needed to calculate the concentrations on the millipore filters. > As for Item I was concerned by the fact`that the sampling locations in the garage were not identified. I mean such data as "at the fueling station" or "near the office," "near the exit," etc. should be recorded for each sample. By activity, I think we would want to know how many cars were fueled during the periods of sampling. If we had this data during the peak periods of activity and during other times, we would have something useful for later comparisons. The matter of marking A.I.S.I. tapes is of considerable importance in relating the spot to the proper time of day. In case the instrument skips or the power fails, it becomes very difficult to account for the spots if they are not marked properly. We don't want to burden you with chores and I know that I wasn't sufficiently detailed in my Instructions when I first visited with you, but I suggest that it would be very helpful if a spot could be marked for each day. Our people who have had considerable experience in this matter, suggest the following type of marking. May 6, 1959 6:10-7:10 P.M. With this type of marking and the arrow to indicate the spot, we can generally trace back and account for all of the spots. /jsthyl Corporation San Francisco, California May 15, 1959 page 2. Incidentally, in going over the first list of samples and results sent to Cincinnati, I note that 24d was a millipore sample to be shipped to Cincinnati. However, this sample was not included in the shipment received by us. Only ID, 4d , 8D and 15D of the millipore filters and lpD and 25D of the tapes were received. Perhaps it was overlooked and will arrive with the next shipment. Our analyses of the four millipore filters showed the following concentrations as micrograms/cubic foot. ID 0.25 4D = 0.10 8D = 0.20 15D *= 0.00 The tapes are now being analyzed, but we will not report these until Phase 1 sampling and analysis is completed. We will then prepare a report for this phase and we should have it ready before Phase is completed. I am looking-forward, to seeing you on May 21 and I hope that everything goes smoothly in the meanwhile* Best regards, A JC :pn cc: Dr. R. A. Kehoe J . Choiak P.S. The millipore filters and the A.I.S.I. tape for the week ending 5**il"59 were t.use received. Your note was read with interest. I see no objection to obtaining data at Y.C. every afternoon possible. However, we should not overlook the night operations and these should also be covered as conveniently as possible. I would also make sure that some data for morning operations are collected. So long as all Y.C. operations including peaks and lulls, are covered, I see no reason why sampling schedules can*t be revised provided the information obtained can still be considered truly representative of the operations. Your difficulty with the power failure is not unusual. When this happens, please mark the tapes, estimating as closely as possible the time that the power was cut off. KfT