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Regular City Council Meeting Monday,April 13, 2015 Page 19 City Engineer Marc Culver provided a presentation to the City on the current pavement indexing system, the City's Pavement Management Plan (PMP) and is- - sues found in Roseville and around the State of Minnesota with delamination of the pavement on local roads. Mr. Culver reviewed current pavement maintenance strategies with review using the Pavement Condition Index as a model, whereby roads were periodically rated and inventoried for cracks, potholes and other distresses; and their condition cal- culated and rated using the index. Mr. Culver advised that the condition index was continually projected based on the last rating, time elapsed, and maintenance history tracked. Using current indexing, Mr. Culver advised that the budget al- lowed for rating approximately 13 miles per year, and it takes approximately 10 years to rate local roadways throughout the entire community. Mr. Culver reviewed the current maintenance program and timeline for a typical Roseville road: • New pavement • Seal coat year 2 or 3 • 2°d application of seal coat year 9— 11 • 3rd application of seal coat year 16— 10 • Mill and overlay(2") with condition index 35 —60 • Full depth m& 0 with condition index under 30 • Annually crack and joint seal ahead of seal coat projects • Patching • Program goal is to maintain an average condition index of 75 Mr. Culver advised that another factor and new reality to consider was the delam- ination problem being experienced in the area, with distressed pavements from the top layer peeling off in strips. Mr. Culver noted that this was being found exclu- sively on roadways with a seal coat application; and the current theory in the in- dustry was that moisture was being trapped by the seal coating and eroding the wear course (top layer of pavement). Since it was a difficult thing to duplicate in a laboratory setting, Mr. Culver admitted that the definitive cause and a complete range of pavements affected remain an unknown at this time,but the biggest issue seen to-date is delamination in early stages followed by a rapid acceleration at that point. Mr. Culver noted further research was needed to determine if this issue was exclusive to Minnesota pavement mixes only, and determining how and where the problem is in the interaction between the pavement mix and seal coat- ing. Mr. Culver provided recent photos of this issue in various areas throughout out the City, as well as a map showing the street segments affected and showing the City's potential exposure. Based on the City's potential exposure, Mr. Culver re- viewed the new reality of a future condition index curve as the backlog increases