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006 RESOLUTiOE 93--002 <br /> Page 4 <br /> <br />designates our city in Seismic Zone #4. This is the <br />highest seismic risk zone in a 4-tiered hierarchy which <br />rates the potential risk for seismic activity by <br />geographical areas. <br /> <br /> 3. As amended, subsection (a) of section 1002 of the Uniform <br />Mechanical Code, 1991 edition, will read as follows: <br /> <br /> Sec. 1002. (a) General. Supply air return air and <br />outside air for heating, cooling or evaporative cooling <br />systems shall be conducted through duct systems constructed of <br />metal as set forth in Tables Nos. 10-A, 10-B and 10-C; metal <br />ducts complying with U.M.C. Standard No. 10-2 with prior <br />approval; or factory-made air ducts complying with U.M.C. <br />Standard No. 10-1. Ducts, plenums and fittings may be <br />constructed of asbestos cement, concrete, clay or ceramics <br />when installed in the ground or in a concrete slab, provided <br />the joints are tightly sealed. <br /> <br />EXCEPTION: Supply air duct, on the discharge side of an evaporative <br />cooler, shall be conducted through rigid metal ducts constructed as <br />set forth in tables nos. 10-A, 10-B and 10-C, and unless prohibited <br />by structural conditions shall be graded in the direction of the <br />supply outlet. Factory made air ducts complying with UMC standard <br />no. 10-1 shall be limited to installation in a vertical position <br />only. <br /> <br />Note: Vertical shall be defined as not more than forty-five (45) <br />degrees from the vertical. <br /> <br /> Corridors shall not be used to convey air to or from <br />rooms if the corridor is required to be of fire-resistive <br />construction by Section 3305 of the Building Code. <br /> <br /> Concealed building spaces or independent construction <br />within buildings may be used as ducts or plenums. <br /> <br /> When gypsum products are exposed inducts or plenums, the <br />air temperature shall be restricted to a range from 50°F. to <br />125°F. and moisture content shall be controlled so that the <br />material is not adversely affected. Gypsum products shall not <br />be exposed in ducts serving evaporative coolers. <br /> <br /> Venting systems and exhaust ducts shall not extend into <br />or through ducts or plenums. <br /> <br /> 4. The City Council hereby finds and determines that the <br />above amendment to subsection (a) of section 1002 of the Uniform <br />Mechanical Code, 1991 edition, is necessary for the following <br />reasons: <br /> <br />The amendment is designed to mitigate a problem arising <br />due to perpetual water chemistry, and high velocity winds <br /> <br />4 <br /> <br /> <br />