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QBOLTON & MENK Real People. Real Solutions. August 6, 2024 Mr. Lucas Miller City of Arden Hills 1245 W Highway 96 Arden Hills, MN 55112 Re: Change Order 1 Recommendation 2024 PMP Street & Utility Improvements City of Arden Hills, Minnesota BMI Project No. OT1.130168 Dear Mr. Miller: Attachment A e 9 Ph: (952) 890-0509 Fax: (952) 890-8065 Bolton-Menk.com We are recommending approval of the Change Order No. 1 for the above referenced project and contract. This change order became necessary after our observations and notification from the prime contractor, S. M. Hentges and Sons, Inc., that the subgrade on Royal Hills Lane did not have the strength to support grading of the existing gravel and subsequent paving. After viewing the site, it was obvious that the problem existed as there were major ruts in the gravel base and that attempting to grade out the ruts would only make the situation worse. The geotechnical report warned of this situation indicating that if the material in the subgrade was subjected to significant moisture and then heavy vehicle traffic, that it may become too soft to support construction vehicles. Unfortunately after the reclamation of the pavement surface and gravel base occurred, the site received significant rain events and the subgrade because soft. This was not the fault of the contractor, they were timely in attempting to grade the road for pavement, but the rain has been occurring with high frequency all summer. Options included 1) Attempting to "farm" the subgrade meaning that the subgrade could have been exposed over a series of days to dry out and hopefully regain strength. That was not a viable option as rain was expected in the forecast and the problem would likely have gotten worse instead of better. 2) Completing subgrade excavation and replacement of the subgrade with stabilizing aggregate. This was seriously considered, including receiving a cost estimate of approximately $48,000, for implementation. This would have been feasible but would have taken significant time and serious disruption to the traveling public using this road. 3) Completing a cement stabilization of the existing gravel and subgrade. This process involves placing cement on the gravel and then mixing it in with a nominal amount of water to activate it and smoothing and compacting the gravel surface with the cement infused. The product is then ready to be paved over in about 3-4 days. The contractor provided a cost estimate of about $38,000. This process had a lower estimated cost, less disruption to the community, and is also an opportunity to complete this process in Arden Hills that has never been attempted before. H:\ARDH\OT1130168\7-Construction\D-PayApplications\Payment 3 including C01\Change Order 1\Change Order 1 Recommendation.docx Bolton & Menk is an equal opportunity employer.