6.1 PowerpointWest WWTF Change Order Review
Presented by: Advanced Engineering and Environmental Services, LLC (AE2S)
March 2024
1
Otsego PWSC Meeting
January 25
General
Excavation of the final two structures has encountered adverse soil conditions
Underground conditions appear to be much more variable in the area closer to the creek
The geotechnical/foundations work is on the critical path for maintaining the construction schedule
2
3/17/2021
Otsego PWSC Meeting - West WWTF Update
Change Orders #32 & #33
Cascade Aeration
Admin Building
3
3/17/2021
Otsego PWSC Meeting - West WWTF Update
Summary of Change Orders
Net total of approved change orders: $ 674,858
Project bid amount: $ 33,889,800
Percent change previously approved: 1.99%
Percent Funding Contingency: 5.00%
Proposed Change Orders: $ 218,779
Previous + Proposed: $ 893,637
Percent Previous + Proposed 2.64%
Remaining Contingency $ 800,853
4
3/17/2021
Otsego PWSC Meeting - West WWTF Update
Change Order #32
Title: Rock for Cascade Aeration
Amount: $4,706
Scope of Change: Additional excavation and rock for structure subgrade
Justification/Consideration: Unanticipated groundwater was encountered during excavation. To avoid placing concrete onto wet ground, the area was over-excavated and then brought to the
appropriate grade with imported rock material to allow for groundwater pumping.
5
3/17/2021
Otsego PWSC Meeting - West WWTF Update
Change Order #33
Title: Administration Building Soil Correction
Amount: $214,073
Scope of Change: Soil correction for building foundation
Alternative 1: over-excavate/haul/replace: ~$350,000
Alternative 2 (recommended): Rammed aggregate piers
Proprietary method for improving soft soil conditions
Justification/Consideration:
Soil conditions were found to be “soft” in a deeper layer than indicated on design-phase soil borings
Braun (City-contracted geotechnical engineer) recommended soil correction based upon field observations and field testing
A suitable base is required under building foundations to avoid future building settlement and associated cracking issues
6
3/17/2021
Otsego PWSC Meeting - West WWTF Update
QUESTIONS?
Otsego West WWTF Update
7
Otsego PWSC Meeting
January 25