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<br />50 feet in diameter. An overhead door and condensate ceiling could be installed in the <br />column to allow truck access and would provide approximately 615 square feet of storage <br />area. The composite tank is sh~wn on Figure 6. <br /> <br />Composite Tanks <br /> <br />The composite style tank support pedestal material is changed from a steel plate material to a <br />reinforced concrete material. The main reason that concrete is used instead of steel is that <br />the pedestal portion of an elevated ta.nf is really a large compression member and concrete is <br />a good material for resisting compressive loads. The water holding compartment is <br />primarily a shell in tension that must contain water without leaking. Steel performs very <br />well in tension, and welded seams make for very leak proof jointing. The overall intent of a <br />composite tank is to use materials of construction that are best suited for the particular task <br />that they are being asked to perform. <br /> <br />The capital cost of a composite tank should be higher than the steel tanks. This will be <br />discussed in the cost estimate section of this report. One of the promoted advantages of a <br />composite tanks is that the maintenance costs (i.e. painting costs) of the tank are less than all <br />steel tanks because the concrete pedestal does not need to be painted. This mayor may not <br />be true. In the rawest sense, the City could have an elevated tank with a plain concrete <br />pedestal in which case the maintenance costs would be lower.' But, from an aesthetic point <br />of view a plain concrete pedestal with a painted steel water compartment in certain colors <br />may not be very pleasing. Therefore, it is felt that the concrete pedestal may need to be <br />painted or receive some other surface treatment in order to be aesthetically pleasing and to <br />be comparable with the steel tanks. With this premise, the maintenance cost savings issue <br />tends to be reduced substantially. There would still be some savings, as the interior dry <br />portion of the composite tank could be left unpainted. This would result in an app~o~imate <br />savings of $60,000 every time this portion of the tank had to be painted. The interior dry <br />portion of the tank is also the least severe exposure and it is safe to say that this area is <br />typically painted only every other time that the tank is repainted. Assuming a 15-year <br />general paint life, this means that the interior dry portion of the tank gets painted once very <br /> <br />Water Tower Feasibility Report <br /> <br />29 <br />