Project Overview
DTE Energy retained NTH to assess the condition of the canal wall systems and design corrective actions to ensure the canals remain functional up to the plant’s scheduled retirement in 2040. NTH was selected for this work based on NTH’s previous involvement with various projects at the Monroe Power Plant. NTH developed and executed a plan to assess, rehabilitate, and repair the existing sheet pile walls of the intake and outfall canals at DTE’s Monroe power plant.
Project Scope
In addition to an above-water visual inspection performed by NTH, a below-water dive inspection and sonar survey were performed. In tieback areas, the condition of the wale beams was reported as corroded in all areas with some areas approaching failure. Several tie rods in the intake canal appeared to have failed abruptly. The diving team observed significant scour at the dredge line and holes in the canal sheeting at observed sinkhole locations landward of the sheeting in both the intake and outfall canals.
NTH designed an approach to repair the holes in the canal walls and restore the scoured dredge line. NTH then completed a more thorough condition assessment of the anchored bulkhead systems in the intake and outfall canal areas. The results of the condition assessment were presented in a risk register to prioritize maintenance and repairs and mitigate risks to the operation of the plant. Shortly after NTH reported its findings, a section of the intake canal sheeting deflected approximately four feet toward the canal. NTH mobilized immediately to design and monitor the repair of the deflected sheeting. A second repair was later conducted in another area of the intake canal to restore structural integrity and accommodate planned dredging of the intake canal.
NTH was able to help DTE achieve their goal of rehabilitating the canal sheet piling and bracing systems to sustain plant operations until retirement of the facility. NTH’s prompt response and effective design helped DTE avoid additional ground loss and wall deflection that could have impacted adjacent structures and potentially reduce the energy-generating capacity of the plant.
Client Benefit
NTH used their engineering expertise to provide DTE with prompt and effective solutions that helped DTE avoid more costly failure of the aging lateral restraint systems in the intake and outfall canals in the future. NTH’s prompt response helped DTE avoid further wall deflection that would have presented a danger to site personnel and potentially reduce the energy generating capacity at the plant.
