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Mr. Charles D. McGinnis County Manager Cabarrus County October 19, 1983 Page 2 2. A non-reproducible drawing was made for the record showing the approxi- mate location of joints, steps, channel reinforcements, the inspection holes previously cut in the masonry and location of photographs which we took. Our measurements of the amount the wall leans were included. 3. U. S. Post Office Department structural Drawing A-l, dated 3/16/66, George A. Thomason & Associates, Inc. Architects was studied to deter- mine the wall design. 4. From the information shown on the wall section and the data gathered in the field a comparison was made with the cantilevered retaining wall design shown on Pages 13-8 and 13-9 of the "Concrete Reinforcing Steel Institute Design Handbook, Working Stress Design 1963 ACI Code." Different grades of steel used in the handbook and that specified on the Drawing A-1 were taken into account. Our observations follow. 1. The wall is approximately 320' long, divided into five sections varying in total height, including the parapet, above the pavement from approxi- mately 20' to approximately 17'. The wall is leaning. The worst portion is the center section directly behind the Post Office. This section is approximately 80' long and varies in height from 18'-4" to 20'. Depending on where it is measured it leans as much as 15" from top to bottom and as little as 11-3/4". Steel channels were bolted near the top of thewall as reinforcements. Several inspection holes have been cut in the wall. 2. The brick parapet extending approximately 43" (13 brick coarses) including the cap above the top of the concrete retaining wall was measured to lean 6-1/2". Eight brick courses below the top there is a 3/4" wide horizontal crack on the back face and the top eight courses are shoved approximately 1" horizontally towards the Post Office. This section of the wall has already failed. It only needs a slight amount of force as could happen with a automobile coming off the parking lot and nudging the fence to knock it down. Ice build up could trigger a failure. The appearance of part of the front face of the wall indicates that this has occurred before and we expect it will occur again. 3. The design of the wall does not provide for any fill above the top of the concrete nor does it provide for any load on the fill at the top of the wall. Both of these conditions are violated. There is fill all the way up to the bottom of the cap which imposes at least 3' more load than the wall is designed for. In addition the parking lot will provide some surcharge with automobiles and small truck traffic. The wall was not designed for this condition.