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WSB Pavement Management Report Page X10 Chip Seal Chip sealing process involves an application of a uniform layer of emulsified asphalt followed immediately by a layer of cover aggregate across the pavement surface. Pre -sweeping and filling of all cracks shall be done prior to the chip seal application. Chip sealing creates a waterproof surface membrane to the existing membrane, which helps to slow down the deterioration of the pavement from oxidation as well as to prevent the intrusion of water. Chip sealing is typically completed one year after crack sealing. Normally, a good chip seal placed on a newer road can last 5 to 10 years. This assumes the chip seal is protected during placement to allow proper time to cure. Other factors which affect a chip seals performance include the type of binder that is used, the condition of the underlying road and external factors such as plow damage. It is the responsibility of the owner to ensure that these external factors do not contribute to premature failure of a chip seal. It is important to note that chip seals can be effective if constructed properly and if placed on a road that is a good candidate for chip seal. Field surveys will assist in determining which roads are candidates for a chip seal. WSB would recommend the City to reference MnDOT Spec 2356 or the 2006 Minnesota Chip Seal Handbook for guidelines to use when chip sealing. It would be our recommendation that on residential streets, the City use CRS - 2 oil with 1/8" Dresser Trap Rock at a rate of .24 to .26 gallons per square yard. On arterials with no bike traffic, it would be our recommendation to use FA -2 aggregate with CRS -2P emulsion at a rate of .26 to .28 gallons per square yard. On heavy commercial streets, it would be our recommendation to use FA -3 aggregate with CRS -2P emulsion at a rate of .35 to .4 gallons per square yard. The larger size aggregate will withstand the heavier vehicle traffic. Fog Seal WSB would recommend the City reference MnDOT Spec 2355 for more information on fog sealing guidelines. Fog sealing is typically completed one year after crack sealing. Typically, a fog seal will last 3 to 5 years. It is important to note that while the color of a fog seal may fade as early as a year after its application, a fog seal remains effective for as many as 2 to 4 years. Fog sealing is another type of preventative maintenance in which only the asphalt emulsion is applied to the roadway to protect the roadway surface from environmental aging, moisture damage, and oxidation. This preventative maintenance technique will not add any strength to the pavement. Micro surfacing WSB would recommend the City reference MnDOT Spec 2354 for more information on micro surfacing guidelines. Micro surfacing is a mix of crushed aggregate, mineral filler, and latex -modified emulsified asphalt. It is applied by a truck equipped with a squeegee or spreader box. Micro surfacing can be applied in multiple layers. It is effective at sealing low -severity cracks, including fatigue cracking, longitudinal cracking, and transverse cracking. It also addresses raveling, friction loss, moisture infiltration, bleeding, and roughness. Micro surfacing is often selected to inhibit raveling and oxidation, as well as improving surface friction and filling minor irregularities and rutting in a roadway. A micro surfacing treatment can be expected to extend a roadway's life by 3 to 6 years, depending on the number of layers applied.