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August 2002 -13- 003 -2203 <br />• 2.2 Underdrains <br />2.2.1 Primary Underdrain <br />Ames constructed approximately 2,370 linear feet of Primary Underdrain in the Phase IVa <br />Area during the 2002 construction season. Record Drawing No. 2 shows the location of the <br />Primary Underdrain. The cross - sectional dimensions of the Primary Underdrain were a <br />nominal 5 feet wide by 3 feet deep, providing a cross - sectional area of 15 square feet, as shown <br />on Construction Drawing 13, Detail 1. Ames excavated the Primary Underdrain trench to the <br />minimum dimensions, and placed geotextile and OF in the trench. Ames placed SSF over the <br />geotextile to a minimum depth of 6 inches. The Primary Underdrain geosynthetic installation is <br />discussed further in Section 3.1. Approximately 1,315 cubic yards of UF; 220 cubic yards of <br />SSF, and 47,400 square feet of geotextile were used to construct the Primary Underdrain. <br />CC &V elected to gravity drain the underdrain sumps into the VLF. <br />• 2.2.2 Secondary Underdrain <br />Ames constructed approximately 626 linear feet of Secondary Underdrain in the Phase Wa <br />Area during the 2002 construction season. Record Drawing No. 2 shows the location of the <br />Secondary Underdrain. The cross - sectional dimensions of the Secondary Underdrain was <br />nominally 4 feet wide by 2 feet deep, providing a cross - sectional area of 8 square feet, as shown <br />on Construction Drawing 13, Detail 2. Ames excavated each Secondary Underdrain trench to <br />the minimum dimensions, and placed geotextile and OF in the trench. Ames placed SSF over <br />the geotextile to a minimum depth of 6 inches. The Secondary Underdrain geosynthetic <br />installation is discussed further in Section 3.1. Approximately 186 cubic yards of UF, 46 cubic <br />yards of SSF, and 8,764 square feet of geotextile were used to construct the Secondary <br />Underdrains. <br />• <br />1: WO12203 W4001CenRep0802V0032203040D 04740W.doc Golder Associates <br />