Agenda Packets - 1990/06/04 - Laserfiche WebLink

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• MEMORANDUM Memo To :Mayor and Council Members From :Ric Minetor, City Engineer/Director�/ of Public Works Date :May 30, 1990 i�y� Subject :1990 Street Maintenance Program We are preparing the specifications and documents for the 1990 Street Maintenance program. This past year we received some complaints about the loose chips that are inherent in seal coating. There was some stripping of chip after the sweeping last fall, and we have found that the majority of the cities are having similar problems . At this time we do not have an explanation for the higher than normal chip loss. However, their is some speculation that the weather and the asphalt emulsion may have been factors. It does not appear to be a problem for this year's program, and many agencies are continuing with chip sealing, but with additional material testing. The street maintenance program is primarily intended to • 'waterproof' the street surface, increased skid resistance and a uniform surface are additional benefits. The traditional method of achieving these goals is to seal coat with sand, pea gravel, or crushed rock chips. Sand seals tend to last only 1 to 2 years. Pea gravel lasts longer and usually provides at least 3 to 4 years of service. Chip seals (as we used last year) are the highest quality lasting 5 to 7 years and providing the best skid resistance. The better the skid resistance the quicker a vehicle can stop, and the better it can start up in slippery conditions. An alternative to seal coating is a method called 'Slurry Seal' . This process involves using chips as in a chip seal, but the --„ ' . - - $ ' . w' th a •uick settin. emulsion. This process almost eliminates chip loss problems and is reputed to be able to provide a minimal amount of filling of depressions or wheel ruts. The main detriment is that a street must remain closed to all traffic for at least a few hours and in some cases overnight. Another detriment is that few contractors in this area use this process. The only other reasonable alternative is a thin overlay. This may involve pavement grinding and requires adjusting manholes, water valves , and other structures . The resulting surface is the highest quality of the various techniques , but reflective cracking may reduce this benefit within a few years. The biggest drawback is the cost, which can be up to 3 times the cost of a • chip seal.