Agenda - Council - 08/24/2021 - Laserfiche WebLink

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CC Regular Session Meeting Date: 08/24/2021 Submitted For: Joe Feriancek, Engineering/Public Works By: Joe Feriancek, Engineering/Public Works Information 5. 18. Title Adopt Resolution #21-246 Authorizing Change Order No.1 for Tiger Street Reconstruction, Improvement Project #21-02 Purpose/Background: Purpose: The purpose of this case is to adopt Resolution #21-246 approving Change Order No.1 for Tiger Street Reconstruction, Improvement Project #21-02. Background: The purpose of Change Order No.1 in the amount of $50,638.69 is to allow the contractor to remove unsuitable materials from the road core (subgrade soils immediately beneath the pavement section) which were discovered during construction. The work covered by this Change Order has been completed, as it was necessary to complete before placing the new aggregate base and pavement. During construction, the street was not passable after removal of the existing pavement and gravel base, as the unsuitable material would not support vehicles.The total contract price including this change order is $275,190.88, the engineer's estimate for this project was $302,770.50. The plans identified 100 cubic yards of unsuitable materials to be removed from the road core based off the geotechnical report and Staff estimation of depth and area of removal. Once excavation began, it was discovered the areas of unsuitable material were larger than anticipated, and deeper on average than anticipated from the soil borings. A total of 1,093 additional cubic yards of unsuitable materials needed to be removed as reflected in attached Change Order No.1. If unsuitable materials are not removed, the new pavement will not have adequate support from the subgrade soils and will not likely reach a 60-year design life. Tiger Street was built in 1991, and is being reconstructed after 30 years, but the pavement has been in noticeably poor condition for many years, during which time Staff has received numerous complaints about the condition of this pavement. On future projects, Staff will take additional steps in an attempt to avoid similar change orders due to removing poor subgrade soils. First, after reviewing the original soil borings, if questionable materials are discovered and material transition zones exist, additional soil borings will be considered to more accurately locate the extent of the unsuitable materials. This may include additional borings in adjacent drive lanes, as a large area of the unsuitable soils removals under Tiger Street was located in a narrow band and didn't cross into both lanes of the street. Second, Staff will use a larger factor of safety to account for the depth of excavation required to ensure all unsuitable materials can be removed without overrunning the estimated quantities. A copy of Change Order #1 is attached, including the Contractor's and the City Engineer's signatures. Upon City Council approval, the City Administrator will sign the Change Order, authorizing payment for the work. No extension of time is approved as part of Change Order No.1. Funding Source: