09-25-2013 Council Agenda - Laserfiche WebLink

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2.32 Existing Pavement and Geotechnical Conclusions There is a high level of surface cracking along with a large amount of patches and potholes on the existing streets. Staff believes there are several issues at work relative to the current state of the pavements: • Streets with inadequate crown and lack of formal edge drainage conveyances (i.e. concrete curb and gutter) allow water to pond in small depressions and scour the pavement surface. As the street ages, depressions in the pavement trap water, subjecting the pavement to freeze -thaw pop -outs and edge cracking. This deterioration eventually forms potholes over time. • A lack of aggregate base does not allow for an adequate spread of vehicle loading over the roadway subgrade, resulting in pavement damage over time. • The silts and clays found in the northeastern portion of the project likely have inadequate drainage causing freeze -thaw damage within the roadway. • The bituminous overlay installed in the late 1980's is over 25 years old and has reached the end of it's useful life. • The streets in the Arkwright- Sunrise neighborhood have deteriorated to the point at which routine maintenance is no longer cost - effective. Correcting the drainage problems on the streets, as well as constructing a new pavement section to the most current standards, allows for a high - quality, long- lasting product, and is considered critical to the performance of any road cross - section for this project. 2.4 Existing Curb The majority of the project streets do not have concrete curb and gutter. The absence of a curb and gutter with a concrete gutter pan forces storm water to flow along the edge of the existing bituminous road and boulevard edges often resulting in the following: • Deterioration and erosion of boulevard edges. • Pooling of water that may spread into the drive lanes and driveways. • Deterioration of bituminous pavements which leads to weakened edge support and poor drainage conveyance as depicted in Figure 2 on the following page. • Deterioration of driveway ends due to freeze -thaw weakening of the pavement. • Improper containment of vehicles and plows within the roadway section. • Difficulty implementing future maintenance treatments. 8 18