The similarities between Potawatomi State Park’s observation tower and the former Eagle Tower at Peninsula State Park are not good news for the people trying to save the structure. The United States Department of Agriculture’s Forest Products Laboratory released its final assessment on Friday, detailing the decay found in the tower’s structural and non-structural members. It is recommended they are not used for anything load-bearing. Missy Vanlanduyt from the Wisconsin State Parks says there are a lot of similarities between Potawatomi’s tower and the now deconstructed Eagle Tower.
Friday’s report was not a death sentence for the tower according to Vanlanduyt, who says the report will be paired with one from the Sturgeon Bay Historical Society and given to a structural engineer to determine if repairs can be made.
FROM THE WISCONSIN DNR
STURGEON BAY, Wis. - Forest Products Laboratory, part of the U.S. Forest Services, Department of Agriculture, has released its report outlining the nondestructive wood testing done on the observation tower at Potawatomi State Park.
Routine inspections of the Potawatomi tower were conducted in the spring and early winter of 2017. During these inspections park staff found visual decay and movement of the structural wood tower members. Wisconsin Department of Natural Resources engineering staff were brought in and conducted additional inspections and recommended further review.
The DNR then again requested assistance from the USDA Forest Service Forest Products Laboratory in Madison, which had gained valuable experience from their inspection of Eagle Tower at Peninsula, which was removed in 2016 after studies found severe wood decay in that tower as well. A new Americans with Disabilities Act compliant tower is set to be rebuilt at Peninsula in 2019.
Forest Product Laboratory staff conducted an inspection on the Potawatomi tower in February 2018 using non-destructive wood-testing methods to examine the wood members and the structural integrity of the tower. Their inspection found significant decay in the structural and non-structural wood members of the tower, and they recommended that the tower be closed to the public and dismantled because the wood elements should not be used any longer in a structural capacity.
According to the recently released report, many of the wood members were found to be deteriorated and it is recommended they not be reused in any load-bearing application.
In January 2019, the department issued a land use agreement to the Sturgeon Bay Historical Society to conduct similar nondestructive testing on the tower. That testing was completed in January and the report is expected to be released by the historical society in the coming weeks.
The department will use both the Forest Products Lab report as well as the report contracted by the Sturgeon Bay Historical Society to request an engineering review of the tower. The engineering firm will be charged with reviewing the reports to determine if and how the tower may possibly be repaired.
Any repairs or a full reconstruction of the tower must comply with the ADA as well as all other applicable state and federal building codes.
The department will continue to work with valued partners such as the Friends of Potawatomi State Park, the Sturgeon Bay Historical Society, the National Park Services, Ice Age Trail Alliance, park visitors and the public to move forward in this process.
"We are eagerly looking for a way to move forward in an effective way to either repair the existing tower or provide new viewing opportunities at the property, both that meet ADA standards, are financially feasible and meet the needs of our visitors," said Ben Bergey, Wisconsin State Park System director. The USDA Forest Service Forest Products Laboratory Nondestructive Assessment of Wood Members in a Viewing Tower in Potawatomi State Park report [PDF] can be found here by clicking.