04-10-10 Special Called City Council Retreat Meeting

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CONCRETE STREET PROGRAM The replacement of asphalt streets and open ditch drainage with concrete curb and gutter streets and underground drainage presents many planning, engineering and funding challenges. Listed below are some of the considerations to move forward with a program oftrus type. . Curb and gutter concrete streets are typically six (6) to twelve (12) inches below natural ground. When completed, the street becomes part of the drainage system. Increased street flooding is to be expected. . Because of the lower elevation, underground storm sewers must be several feet below existing surface drainage. The storm sewer system must not only carry water from the street and surrounding properties, but must also outfall to a suitable surface drainage system. Because of the location of the street, this outfall system could be some distance from the actual street, which can increase the cost of the storm sewer to several times the actual cost to construct the concrete street. . If the Program is to be ongoing, the outfall structures and trunk storm sewers must be sized and placed to serve a large area. In the beginning, these oversize storm sewers must be designed and constructed to meet the ultimate needs of the area. This will cause the initial cost of storm sewer construction to increase. . The need for detention to accommodate the new storm sewer system is also a consideration. This could be difficult to site in developed areas. . Concrete street construction, excluding drainage, is 3-5 times the cost of asphalt street construction. . Concrete streets, while not maintenance free, have a longer life span than asphalt streets. Asphalt streets typically last about 10 years. Concrete streets have a life span of 30-50 years, depending on design, construction and maintenance. . Funding for a program such as this can take several forms. With the large, initial drainage costs in the initial stage, the use of the street maintenance tax would not be feasible in the initial stages of the program. Other funding methods are bonds, certificates of obligation and assessment of adjoining properties. . Selection of candidate streets should be based on traffic, property owners served and other engineering considerations, including drainage outfall issues. Because the drainage issue will initially be the most expensive component and present the greatest planning and engineering challenges, it is recommended that the program begin with the design and construction of trunk storm sewers in target areas, followed by phased design and construction of concrete curb and gutters streets and associated drainage.