03-03-14 Council Packet - Laserfiche WebLink

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DRAFT DRAFT DRAFT conditions within the City and the need for utility repairs or improvements along the individual street segments. Some general assumptions were made regarding the existing soil conditions within the City. It was assumed that the soils in the area south and east of the Rice Creek Chain of Lakes are generally organic with a high groundwater level. Soils north and west of the Rice Creek Chain of Lakes were assumed to be predominately sandy in nature. Past projects in various locations throughout the City have confirmed these assumptions. III. Types of Street Maintenance For clarification, there are four different types of street maintenance that the City performs on our local streets. They include Sealcoating, Mill & Overlays, Reclamation, and Reconstruction. Sealcoating Sealcoating includes pre-sweeping and filling of all cracks in the pavement. A layer of emulsified (liquid) asphalt is applied uniformly across the pavement surface. This is followed by a uniform cover of trap rock chips. Sealcoating creates a surface seal to the existing pavement, which provides additional support for traffic loads, and protection from weather conditions. Sealcoating is recommended for street segments that have an OCI rating of 70.01-100. Mill & Overlays Milling and overlaying is proposed in areas where the existing pavement is in moderate to poor condition, but the underlying soils are in good condition. These streets typically have an OCI rating of 40.01 – 70. The milling and overlaying operation includes edge milling along the existing curb line and overlaying the existing pavement with 1-1/2 inches of new bituminous. Partial replacement of the existing curb may be included with a mill and overlay project. Reclamation Reclamation has been used in the portions of the City where the underlying soils are in good condition, typically the north and west of the Rice Creek Chain of Lakes. A number of the streets in these areas were constructed originally with bituminous curb and gutter rather than concrete. For projects in these areas the City has utilized the reclamation process. Reclamation includes reclaiming (grinding up) of the existing asphalt and aggregate base materials for use as aggregate base for the asphalt pavement. Then a new 2-inch base course and 1-1/2 inch wear course are paved over the aggregate. This may or may not include new bituminous curb. The reclamation process is economical because it utilizes the existing roadway materials. Reclamation is a potential option for pavements that have an OCI of 0 – 40 and are located in the area north and west of the Rice Creek Chain of Lakes. It also can only be used for street segments where no utility improvements are required.