Memorandum from E. E. Howard to General Glen Edgerton

COPY HOWARD, NEEDLES, TAMMEN & BERGENDOFF Consulting Engineers 921 Walnut Street Kansas City 6, Mo. September 19, 1949 General Glen E. Edgerton Executive Director Committee on Renovation of Executive Mansion The White House Washington, D. C. Reconstruction of Executive Mansion Dear General Edgerton May I acknowledge copy of Technical Memorandum No. 5, also of the letter of September 12 by Commissioner Reynolds with memorandum by Mr. Yingling. I concur in the conclusions of Item 13 of Technical Memorandum No. 5. However, the loading as applied to the top of the 8 ft. thick blanket of soft and plastic material underlying the area below Elev. 13.0 seems more critical than the exact intensity of loading at the bottom of the footings. At Elev. 13.0, according to conventional theories of load distribution through soils, the total load of the building, including that imposed by the outer walls and also by the inner footings in any of the general patterns proposed, is pretty well distributed over an area the perimeter of which may be about 12.5 ft. beyond the outer walls. The total area may thus be about 23,000 sq. ft. A lowering of the outer footings 3 ft. would reduce this total "raft area" by about 4 1/2 per cent. Mr. Yingling's conclusions undoubtedly are correct within the range of the information on which they are based. He confirms the comments of my letter of August 30, that these conclusions are based on two small samples of the plastic material. These samples do not necessarily represent the character of material for the full depth of this plastic blanket, nor for the whole area. It would be encouraging to feel that the settlements of the reconstructed White House will not exceed the amounts indicated by Mr. Yingling, either under the disturbance of construction conditions or under conditions which may develop in future decades should there be a marked change in the ground water level to an extent that might affect subsidence. Can we say we know with certainty? To explain my apprehension in this matter I feel I should give you the facts concerning conditions which have developed at the north abutment of our 14th Street Potomac River Bridge. lith placing a large amount of earth filling over an extensive area N ARORIVES <'NATIONAL RECORDS SERVICE