May 7,2015 KSANDER & ASSOCIATES CONSULTING PROFESSIONAL ENGINEERS 130 HUINTER STREET, UNIT 103, PETERBOROUGH, ONTARIO K9H2K8 TELEPHONE (705) 743-9221 FAX 743-0904 Ontario Region Conservation Authority 250 Milroy Drive, Peterborough, Ontario, K9H 7M9 Att. Mr. Dan Marinigh Re: Foundation Condition Needler s Mill Dear Sir, Photo 1. Scenic View As requested, I have performed a preliminary foundation inspection of the above noted building. I have also read and studied previous reports such as from Acres International, 2004 and Geologic 2004 and have the following comments: The Needler s Mill compound actually consist of six separate structures all adjacent to each other. That being, the flour mill, the machine room shed to the flour mill, the deck and veranda to the flour mill, the saw mill and finally the split level wood storage shed. It is interesting that all six structures have independent foundations not related to the adjacent buildings yet depend, somewhat, on the adjacent structural framing for stability. (Not considered good building practice). Photo 2. View showing flour mill, machine shed, veranda and saw mill + storage shed. Needler s Flour Mill The foundation of the main mill consist four heavy steel girders each supported by 3 large 24 diameter reinforced concrete piers. Since, historically, that the mill was actually built downstream and re-located to its present location, the existence of these steel girders would have made the re-location project straightforward and it would have been a logical conclusion to leave them in place and conveniently make them part of the permanent foundation at this new site.
Unfortunately, the bottom of the concrete piers were not accessibly to the author at the time of writing this report. Also, no previous report describes what the piers are actually founding on. It is my opinion, that the piers are likely founded on loose fill on their own without bottom pads which would account for the present condition of the piers. I have attached a sketch Sk-1 marking each of the 12 large piers in question and attempted to photograph each of them with comments to their condition. Photo 3. Pier 1,Heavy corrosion. Unstable. Photo 4. Pier 2,Heavy corrosion. Unstable Photo 5.Pier 3, Some Spalling. Conditon fair. Photo 6. Pier 4, Condition good. Photo 7. Pier 5,Some spalling. Out-of-plumb, condition fair Photo 8. Pier 6 Some spalling. Condition fair.
Photo 9. Pier 7 Condition fair Photo 10. Pier 8 Condition fair Photo 11. Pier 9 Condition unknown Photo 12. Pier 10 Condition good Photo 13. Pier 11. Condition good Photo 14. Pier 12. Condition unkown Photo 15. Typical Steel support girder on concrete pier Condition fair
The Deck and Veranda The deck and veranda foundation consists of 3 small concrete piers supporting the east end of the framing. The west side is attached to the main mill framing and relies on it for support. The 3 small piers have leaned out-of-plumb and severely settled and cannot be considered reliable for support of the framing above. It is likely that this part of the mill was added onto the main mill after the re-location. Photo 16. Veranda Pier. Unstable Photo 17. Veranda Pier, Some corrosion. Unstable Machine Room The machine room foundation consist of a structural floating shallow raft slab that serves the purpose of a structural floor to support any heavy machinery as well as supporting the main timber framing. There are clear signs of heaving and cracking of the concrete and rotting of the wood support framing on top. Photo 18. Machine room slab plus rotted post on top. Photo 19. Rear view of cracked and heaved machine room slab.
Saw Mill The saw mill foundation is similar to the machine room in that it is supported by an exposed shallow structural raft slab. Photo 21. Typical failed slab, sheared around timber post. Photo 22. Settled slab with timber post suspend above it Storage shed The storage shed is a split level structure adjacent to the saw mill building. Photo 23. Outside view of stepped concrete pads. Photo 24. Inside view of stepped concrete pads The pads are shallow and show signs of heaving and settling. Foundation deficiencies The structural integrity of the concrete foundations are critical in maintaining the stability of the timber framing above. Although the loads are relatively light, the locations of the point loads can induce severe local stress on the foundation below. When one pier or area of a support slab has failed it will immediately cause the load to shift to other locations and overload that area. If that location can temporary support the increased load the building temporary appears to be stable as the mode of failure has become what is known as a progressive collapse. On the other hand, if the adjacent support cannot support the extra weight, a sudden catastrophic failure can occur and collapse can be imminent. Foundation deficiencies that need to be address and corrected as soon as possible include but are not limited to: - Severely corroded concrete and reinforcing steel
- Severely out-of-plumb concrete support piers - Severely failed concrete support raft slabs - Severely failed concrete support pads Foundation deficiencies that should be addressed when practical are: - Sandblasting and epoxy protection of steel support girders - Additional lateral steel bracing design for the piers Conclusions and recommendations Unfortunately, I m not aware of any practical methods to conduct the above noted repairs without temporarily lifting and removing the wood timber structure above. The temporary shoring required to support the building in-place while repairs are undertaken requires a reliable and sound subgrade to withstand the loads from shoring jacks and heavy timber cribbing. The sub-grade under the buildings is unsuitable loose wet organic fill. Although, not part of the scope of this report, one should seriously consider the structural condition of the timber framing above the foundation before deciding to move the superstructure and the practicality of re-building or restoring the wood framing. Clearly, there are areas of the timber framing that need re-construction or restoration. Also, once the decision to lift the buildings have been made, it would not be practical to repair the foundations since, in my opinion, they were ill-conceived and have not performing adequately. Instead, it is recommendations that the existing foundations be removed and new foundations be engineered and constructed. The new foundations should be designed to rely on the strong stiff clay strata approximately 6 feet below grade for support and in doing so would not be sensitive to frost action, water table fluctuations, and settlement and should have an indefinite lifespan. Public safety in and around the buildings Since the buildings are located within the village and in a high traffic area, public safety is a concern. It is my opinion that it is unlikely that these buildings will survive the next 10 years without intervention. Therefore, in the interest for public safety, I suggest that a proper perimeter hoarding fence be installed around all the buildings as soon as possible, approximately 20 feet away so as to allow for a possible collapse without danger to the public. Once the hoarding fence has been installed, the following longer term options may be undertaken if desired: Option #1 -Remove the veranda and crawl space skirting of the four mill for future re-construction. -Instigate the first phase of the lifting of the flour mill by installing the required heavy lifting girders and their support cribbing. -Install temporary shoring jacks onto the exterior timber beams of the saw mill and storage shed as per the attached bracing detail Sk-2 or remove saw mill and storage shed in such a way to be able to re-install at a later time. - install a load-bearing 2x6 stud wall inside the machine room shed to support the existing shed roof or remove machine room shed in such a way to be able to re-install at a later time.
-Restrict access inside the buildings. Option #2, -Demolish all the building structures in an orderly and safe way. If you have any questions or I can be of any further service to you, please feel free to contact me. Yours truly, Ksander & Associates Per: Rick Ksander, P.Eng. 05.07.15