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10062 Flanders Court NE – Blaine, MN 55449 – Ph: (763) 780-0450 Fax (763) 780-0452 Z:\PROJ\120180E - LC 2015 Street & Utility Improvements\0071\Change Orders\Memo-072216-CC (Supplemental Agreements 1-3) .docx Memo TO: Honorable Mayor and City Council FROM: Lee Elfering, City Engineer DATE: July 22, 2016 RE: Little Canada Road Improvements Project Supplemental Agreement #1, #2, #3 As the Council is aware the City’s 2015 Street Improvement project includes the reconstruction of Centerville Road. The project is progressing, but there have been some changes that have either been requested to provide for a better overall project or to address conditions that have been encountered in the field. Below is a summary of three Supplemental Agreements that address the field changes to the project. Supplemental #1 – Select Granular Borrow The existing subgrade soil conditions encountered north of the Pioneer Park parking lot on Centerville Road require the addition of fabric, select granular borrow, and draintile to provide an adequate base for street construction. As Centerville Road is a County road, Ramsey County will be responsible for 78% of the cost of this work and the City’s share is 22% as outlined in the cost summary included with Supplemental Agreement #1. Supplemental Agreement #2 – Impacted Soil Disposal During the excavation process petroleum odors were noticed emanating from some of the excavated material from the roadbed. These odors prompted additional site test pits and on-site investigation to determine the source of the odors. It was determined that there was a layer of what appeared to be oiled aggregate that existed under the old roadbed. This oiled roadbed layer was separated from the bituminous surface by clean aggregate base and was therefore not discovered during the pavement removal process. This layer was also not detected in the initial County borings. The material was laboratory tested to be high in Diesel Range Organics (DROs) and therefore if the material is excavated it must be treated as regulated fill and hauled off -site for proper disposal at a landfill or used under the roadbed. As the road is being lowered to accommodate an urban section there is limited to no ability to use the material under the roadbed area. Supplemental Agreement #2 addresses the additional costs to properly haul and dispose of the impacted material at an approved SKB disposal landfill site. The cost of the work is 100% the responsibility of the County.