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Town Talk: Spring asphalt maintenance

The top priority of the Street Department is to maintain the integrity of the street and alley pavements to ensure they are in a safe and useable condition and to ensure proper drainage for storm runoff.

As the weather warms and the snow melts the first maintenance activity we perform is crack filling.

A year or two after a street pavement is constructed, the freeze/thaw cycle of the seasons plus the load of the vehicles driving on it, causes cracks to form about every 40 feet or at the same distance apart as the width of the street.

These cracks, if left open to the environment will allow water to infiltrate into the base aggregate below the pavement and cause more deterioration to the pavement from below due to the same freeze/thaw cycle. As these cracks get wider they may actually begin to sag because the base material is eroded out below the crack, that’s the thump you hear every time you drive over a severe crack. Smaller cracks begin to form around the larger crack until the whole pavement section is cracked and deteriorating at a high rate.

To stop this deterioration, Street Department staff grinds a reservoir over the new cracks shortly after they form in a recently constructed street, then pour a hot sealer material into the reservoir to stop the water from entering the crack.

The sealer material is a rubberized hot asphalt seal material that will last for many years. As the pavement expands and contracts throughout the seasons, the sealer will stretch and compress along with it and remain in-tact.

This operation is performed prior to seal coating and is a valuable procedure to extend the usable life of New Ulm’s street pavements.

After crack filling the Street Department staff turns to permanent pothole repair. The preferred method of repair is called Injection Patching; a process used in the fall to prepare for winter and also in the spring to repair potholes that have developed during the freeze/thaw cycles of late winter and early spring. The injection patching machine carries the hot bituminous oil and the aggregate separately. When the operator is ready to patch a pothole they blow out the pothole with compressed air to clean out any loose debris, then they spray hot oil to coat the entire inside surface of the pothole. The next step is to inject the pothole with aggregate and oil mixture produced by the injection patching machine. This material does not need any further compaction and is now ready for vehicle traffic.

If you have any questions on crack filling or would like to report a pothole call Curt Curry, Public Works Superintendent at 359-8296.

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Editor’s Note: The City of New Ulm presents a weekly column highlighting activities in different departments in the city government. Once a month the city will answer questions from readers. Questions on New Ulm city issues can be sent to comments@ci.new-ulm.mn.us.

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