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262 Mr. Culver reviewed the overall purpose of a Pavement Condition Index model <br />263 where roads are periodically rated and an inventory taken of cracks, potholes, or <br />264 other distresses and a subsequent calculation based on the condition index based <br />265 on those distresses, providing an ongoing and consistent projection for <br />266 maintenance and/or replacement. <br />267 <br />268 Mr. Culver reviewed the City's current maintenance program from when new <br />269 pavement was installed, and a following program of seal coating in years 2 or 3, a <br />270 second application of seal coating in years 7 to 10; a third application in years 15 <br />271 to 8; a mill and overlay to a depth of two inches when the condition index reaches <br />272 35-60, with a full depth mill and overlay with any condition indexes found under <br />273 30. Mr. Culver noted that staff did annual crack sand joint sealing ahead of sea <br />274 coat projects, and other patching with a goal to maintain an average condition <br />275 index of 75. However, Mr. Culver noted that budget factors often dictated the <br />276 amount of roadway in miles that could be addressed in any given year based on <br />277 available resources. Therefore, Mr. Culver advised that those budget <br />278 ramifications and limitations had created a funding backlog unde the current <br />279 policy and current goals of the average condition ' X. <br />280 <br />281 Mr. Culver advised that another factor and new reality to consider wa the <br />282 delamination problem being experienced in the area, with distressed pavements <br />283 from the top layer peeling off in strips. Mr. Culver noted that this was being <br />284 found exclusively on roadways with a seal coat application; and the current theory <br />285 in the industry was that moisture is being trapped by the seal coating and eroding <br />286 the wear course (top layer of pavement). Since it was a difficult thing to duplicate <br />287 in a laboratory setting, Mr. Culver admitted that the definitive cause and a <br />288 complete range of pavements affected remain an unknown at this time, but the <br />289 biggesissue seen to-date is lamination in early stages followed by a rapid <br />290 acceleration at that point. Mr. Culver noted further research was needed to <br />291 determine if this issue was exclusive to Minnesota pavement mixes only, and <br />292 determining how and where e problem is in the interaction between the <br />293 pavement mix and seal coati <br />294 <br />295 As background information, staff advised that since 2005, local agencies <br />296 including the City began using a different "super pavement" mix versus the <br />297 previous low and mid-volume pavement mixes, with the hopes that switching <br />298 would eliminate delamination issues. Mr. Culver advised that MnDOT and <br />299 Ramsey County d begun using the super mix earlier than local municipalities; <br />300 and since most counties as well as MnDOT didn't do seal coating, they were not <br />301 experiencing the same problems but whether or not it was a seal coating issue or <br />302 pavement mix was difficult to determine from their experiences. <br />303 <br />304 Mr. Culver provided photos taken earlier today of this issue in various areas <br />305 throughout the City, as well as a map showing the street segments affected and <br />306 showing the City's potential exposure. Based on the City's potential exposure, <br />307 Mr. Culver reviewed the new reality of a future condition index curve as the <br />Page 7 of 17 <br />