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• • <br />9. Back-flow prevention devices must be installed in line on the water meter <br />service line on all commercial developments. <br />F. Water Line Crossings within the City of La Porte <br />1. Public and private utility crossings other than sanitary sewer: Where a water line <br />crosses another utility other than a sanitary sewer, a minimum of 6 inches of <br />clearance must be maintained between the outside wall of the water line and the <br />outside wall of the utility. <br />2. Stream or ditch crossings <br />a. Elevated crossings <br />(1) Water lines shall be ductile iron pipe and shall extend a <br />minimum of 15 feet beyond the last bend or to the right of way <br />line, whichever is greater. <br />(2) Elevated crossings are preferred to underground crossings: <br />(3) Use.a separate elevated supporting structure for 12 inch and <br />larger water lines. Locate structures a minimum of 10 feet <br />from any existing or proposed structures. <br />(a) Adequate structural capacity shall have been <br />calculated and provided for including considerations <br />for pipe deflection and all applicable loading. <br />(b) Sufficient clearance above bent cap elevation shall be <br />provided where elevated water lines are to be run <br />under bridges. <br />(4) Design elevated crossings with the elevation of the bottom of <br />the water line 2 feet above the 100-year floodplain elevation . <br />(5) Create a high point in the elevated stream or ditch crossing <br />and provide an sir release valve at that highest point of the <br />water line. <br />(6) Provide sufficient span length to accommodate the cross <br />section of future widening of the stream or ditch to ultimate <br />cross section. <br />(7) Base the appropriately spaced columns' support designs on <br />. soil capacity, spacing, loading, and all pertinent structural <br />requirements. <br />(8) Provide pedestrian pipe guards on elevated crossings. The <br />Planning Department can be contacted for this detail. <br />b. Underground Crossings <br />(1) Provide a minimum.4 foot clearance from the top of the <br />pipeline to the ultimate flow line of the ditch. <br />(2) Provide sufficient length to exceed the ultimate future <br />development of the stream or ditch. <br />(3) Water lines shall be C-900 or ductile iron pipe and shall <br />extend a minimum of 15 feet beyond the last bend or to the <br />right of way line, whichever is greater: <br />3. State Highway and County Road Crossings <br />a. Extend carrier pipe from right-of-way to right-of way <br />Water System Design Criteria Page 7 of 12 <br />