Adopt Resolution #24-276 Approving Change Order No. 3 for Improvement Project #21-08, Water Treatment Plant Trunk Watermain Improvements

Purpose:
The purpose of this case is to adopt Resolution #24-276 approving Change Order No. 3 for Improvement Project #21-08, Water Treatment Plant Trunk Watermain Improvements.    
 
Background:
During construction, field changes were required to address two separate items that were not accounted for in the plans and specifications.
 
Open Cutting of Bunker Lake Boulevard
At the intersection of Bunker Lake Boulevard and 143rd Ave/Azurite St., the plans called for the 20-inch trunk watermain proposed under 143^rd Avenue to connect to the existing 16-inch watermain located along the east side of Bunker Lake Boulevard using horizontal directional drilling (HDD) methods.  A proposed drilling pit was planned at the tee of the two watermain pipes, but because the existing 16-inch pipe was fairly deep and was located under the edge of the driving lane for northbound Bunker Lake Boulevard, this work would have required both lanes of Bunker Lake Boulevard to be closed to traffic for multiple days.  Anoka County would not allow Bunker Lake Boulevard to be closed for multiple days during the work week (Monday-Friday).  Instead, they agreed to a 1-day Saturday closure. Additionally, it was not possible to connect the 20-inch pipe to the existing 16-inch pipe without using a wet tap to keep the 16-inch trunk main in service.  It was therefore determined this work would need to occur on a Saturday and that the 20-inch pipe being extended across Bunker Lake Boulevard must be open cut rather than directionally drilled. 
 
Anoka County issued a road closure/detour permit and the work was done on Saturday, August 24, 2024.  The City agreed to use Time and Materials (T&M) for the necessary change order work. Attached is a detailed summary from Northdale outlining the effort needed to complete the work and account for the time and materials used. The total cost for pipe related work is approximately $31,000.  The remainder is for other subcontractors work such as paving and traffic control during the 1-day closure. The total cost of this change order is $69,595.11.
 
Buried Concrete Removal
A large mass of buried concrete with embedded large diameter rebar was encountered under the east end of 143^rd Avenue during watermain construction.  The buried concrete extended approximately 5-feet deep by approximately 185-feet in length and about 8-feet wide, essentially blocking the trench required to install the water main for 185 feet.  This required the concrete to be removed as a "change in conditions."  This work required an additional larger backhoe with a concrete ripper/jack hammer attachment. Attached is a letter from Northdale outlining the effort it took to remove this concrete. The total change order for their time and materials is $55,170.34. 

This is an after-the-fact change order.  As always, staff strives to process change orders before work is completed. However, after-the-fact change order approvals are sometimes required to prevent project delays and even larger project cost increases resulting from contractor downtime while waiting for the next Council meeting to obtain approval before the work can be completed.  This can increase project costs by thousands to tens of thousands of dollars for each day work is halted. 

Change Order No. 3 results in increased project costs amounting to $124,765.45.
 
These costs will be funded from water enterprise funds.  

Staff recommends adopting Resolution #24-276.  As previously noted, this work has already been completed.  

Adopt Resolution #24-276 approving Change Order No. 3 for Improvement Project #21-08, Water Treatment Plant Trunk Watermain Improvements, in the amount of $124,765.45.