Agenda - Council - 04/28/2020 - Laserfiche WebLink

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CC Regular Session 5. 11. Meeting Date: 04/28/2020 By: Bruce Westby, Engineering/Public Works Information Title Adopt Resolution #20-084 Accepting Proposals and Awarding Contract for 2020 Ground Penetrating Radar Pavement Evaluations, Improvement Project #20-06 Purpose/Background: Purpose: The purpose of this case is adopt Resolution #20-084 accepting proposals and awarding a contract for 2020 Ground Penetrating Radar Pavement Evaluations, Improvement Project #20-06. Background: On several occasions in recent years, pavement management program (PMP) projects listed in the City's Capital Improvement Program (CIP) could not be completed as proposed due to deficient bituminous pavement sections. This generally resulted in one of two outcomes. Either the project moved forward with significant project cost over -runs due to an increase in project scope needed to address the pavement deficiencies, or the project was canceled. When a project is canceled, property owners expecting the project to occur that year must then be informed that the project is no longer moving forward. In addition, replacement projects are typically explored and as has often been the case the replacement project is often not found to be feasible due to the pavement section again being deficient. Pavement sections are considered deficient when the section is not thick enough to support pavement milling operations, or when the structural integrity of the pavement is so poor that the pavement will fall apart upon attempting to mill it. A prime example of this occurred in 2017 when several street segments in the Rivers Bend development were proposed to receive mill and overlay improvements in 2017, but after soil borings and pavement corings were completed as part of the Feasibility Report process it was discovered the pavement was too thin to effectively mill and overlay so the street had to be reconstructed instead, which was done in 2018. As a result, in 2017 Staff researched available options for evaluating the thickness and structural integrity of existing pavement sections and determined that two primary options existed. The first option is to physically collect and examine pavement cores. Cores are collected at pre -determined locations using a hole saw to extract a cylindrical pavement core from the street. The core is then examined to determine the thickness and structural integrity of the pavement section at that location. Though this provides the most conclusive evidence as to the depth and integrity of the existing pavement section, it only provides information at the location where the core was taken. As has been found numerous times, the thickness and structural integrity of pavement sections differs significantly from one location to another. The second option is to collect ground penetrating radar data. Ground penetrating radar was previously primarily used to locate items buried underground such as vaults and graves. However, this technology is being used more and more frequently to evaluate existing pavement sections. Data is collected in 1 to 2 foot intervals along a street segment, depending on the speed at which the vehicle the radar unit is attached to is traveling. The radar is strong enough to penetrate the top foot or so of the pavement section, revealing changes in material densities between the bituminous or concrete pavement section, the aggregate base section, and subgrade soils beneath. A minimal number of pavement cores are also extracted on the street segmented being evaluated to calibrate the readings and