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<br />Other design configurations will relieve ponding and flooding during normal rainfall <br />events that occur more frequently than the 100-year frequency. Depending on the design <br />frequency, a 3-year design costs approximately 20% less than the estimates presented <br />above and itemized in Table-2 thru Table-7. <br /> <br />3.5 Alternative 4 Lower Roadway Profile from Mesquite Dr. to Spruce Dr. South and <br />Replace Storm Trunk Line with a 5-year Capacity Trunk Line <br /> <br />Alternative 4 is based on lowering Fleetwood Drive from Mesquite Drive to Linwood Dr. <br />and removing and replacing the existing storm sewer trunk line. This alternative provides <br />a level of protection for a 5-year event and path for sheet flow leave the subdivision. The <br />average drop in the profile is 1.25-feet with the deepest drop accruing at Mesquite of <br />1.70-feet and the smallest at Spruce Dr. of O.04-feet. <br /> <br />Conveyance calculations were performed using a profile grade sloping down toward <br />BI06-02-00 at 0.078% between Mesquite and Linwood and profile grade of 0.186% <br />between Linwood and Spruce Dr. From the ponding analysis depicted in Exhibits 3, 4 & <br />5 properties become inundated between I-foot and 1.5-feet above the top of curb. Under <br />proposed conditions, Alternative 4 conveys about 74.0 cfs at a depth of 1.20-feet in the <br />northern roadway section and approximately 114.0 cfs at a depth of 1.20-feet for the <br />southern section roadway section. This is in addition to 5-year capacity of the storm <br />sewer trunk line at 216.0 cfs for total discharge equal 330.0 cfs. <br /> <br />Estimated construction costs are approximately $1.97 million with a 10% contingency <br />and $2.21 million after engineering and surveying. <br /> <br />3-4 <br /> <br />Klotz Associates Project No. 0127.009.000 <br />May 2009 <br /> <br />Fairmont Park East & Brookglen Drainage Study <br />City of La Porte <br />