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HomeMy WebLinkAboutFebruary 02, 2023 - Council - AddendumTHE CORPORATION OF THE MUNICIPALITY OF BAYHAM COUNCIL MEETING ADDENDUM MUNICIPAL OFFICE Thursday, February 2, 2023 13.2 C Report CAO-11/23 by Thomas Thayer, CAO|Clerk re Stabilization Measures – Port Burwell Lighthouse REPORT CAO TO: Mayor & Members of Council FROM: Thomas Thayer, CMO, CAO|Clerk DATE: February 2, 2023 REPORT: CAO-11/23 SUBJECT: STABILIZATION MEASURES – PORT BURWELL LIGHTHOUSE BACKGROUND On January 5, 2023, Council received Report CAO-02/23 re Port Burwell Lighthouse Heritage and Structural Assessment. The Report addressed the findings from the initial assessment of the cladding on the Lighthouse, received in October 2022. The Report recommended a comprehensive heritage and structural assessment of the Lighthouse, stemming from initial findings and concerns about structural compromise. Council passed the following motion: Moved by: Councillor Emerson Seconded by: Councillor Chilcott THAT Report CAO-02/23 re Port Burwell Lighthouse Heritage and Structural Assessment be received for information; AND THAT Council accept the Proposal for Heritage Architectural Services for the Port Burwell Lighthouse Recladding Project - Cladding Review, Structural Report, and Preparation of Existing Condition Drawings in the amount of $19,935.00. This Report discusses the findings of the structural assessment by Cooke and Associates Ltd. Consulting Engineers (Cooke) and costing estimates from a+LINK Architecture Inc. (a+LINK) to address immediate stability and integrity concerns prior to a more comprehensive restoration approach. DISCUSSION In accordance with Council’s direction, a+LINK was advised of Council’s desire to continue with the full heritage and structural review. a+LINK coordinated two days to attend the Lighthouse for data gathering and assessment of various elements of the structure. The structural assessment was conducted on January 17, 2023 by Jonathan Dee of Cooke. Also on-site was Tim Finch of a+LINK. Municipal supervisor representatives were the Manager of Public Works, the Roads Operations Supervisor, and the CAO|Clerk. During the course of the structural assessment, extensive deterioration was discovered in the main support columns of the Lighthouse, particularly where the support columns intersect with the existing concrete base. As per Jonathan Dee of Cooke: “During the course of investigation of the Port Burwell Lighthouse, extensive deterioration (rot) was identified at the main columns at each corner of the lighthouse, near the top of the concrete foundation wall. The degree of deterioration is such that the capacity of these columns is seriously affected (with over 80% section loss in some cases). The lighthouse is a tall, slender structure and is subjected to significant wind loading, especially as it sits atop a rise adjacent to the water. Being a light, wood-framed structure, wind loadings have the potential to induce overturning about the base of the lighthouse. These would normally be resisted by additional compression in the columns on the leeward side of the building and tension in the columns on the windward side of the building. Resistance to these forces is presently compromised due to the condition of the columns. As such, and in addition to the risk of failure from gravity loads on the columns, there exists an overturning risk for the lighthouse.” Due to the above, staff have engaged in immediate discussion with a+LINK and Cooke regarding short-term mitigation measures to address the potential of a compression and/or wind-induced failure of the Lighthouse. A solution has been proposed by Cooke and a+LINK. The solution proposes a collar installed into the exterior of the Lighthouse at the third landing level with helical pile hold-downs at ground level. The piles and collar would be connected with eight (8) guywire cables, one per vertex, suitable for the stabilization of the Lighthouse in the immediate term. Construction is estimated to take approximately one (1) week. A schematic of the proposed design is attached hereto, and its purpose is spoken to by Cooke as follows: “The purpose of the stabilization is to mitigate the risk of overturning as economically as possible, using guy-wires and a steel collar to limit the amount of lateral movement of the lighthouse, until such time as a permanent solution can be developed and constructed. While scaffolding or large supporting members would be very costly, other economical approaches were considered, mainly involving strapping along the columns and secured at the base, but were rejected due to the potential interference with future work, risks in terms of the extent of rot that may be encountered along the columns, and because of the potential failure by prying action should there be a compressive failure on the opposite side of the lighthouse.” The complete correspondence from Cooke is attached. Based on discussions with Cooke and a+LINK, they have advised of a cost for this solution of $84,000. This is not an insubstantial allocation for what is effectively a temporary solution, however, the solution has been deemed the most practical and economical by Cooke for the purposes of this project and given the possible failure modes for the Lighthouse. A costing breakdown is below: Piers $ 20,000 Steel Collar $ 10,000 Guy Wires $ 10,000 Vertical Access $ 15,000 (Manlift and Boom Truck) Material Testing $ 2,000 Labour $ 16,000 ( 2 Labourers, 1 Welder, 1 Superintendent, 1 Week) Subtotal $ 73,000 Contractor OH&P $ 11,000 (15%) Total $ 84,000 It is also recommended, that due to the nature and accelerated construction timeline, including unexpected construction issues, the Municipality also allocate a 30 percent contingency. In Q1 2022, a surplus allocation was made of $125,000 to the Facilities Reserve for works at the Port Burwell Lighthouse. Based on the above costing estimation provided, the Reserve does have enough allocated to support immediate stabilization efforts. It should also be noted that Robinson Street is currently closed adjacent to the Lighthouse due to overturning risk. It is expected that this solution will help mitigate those risks, and risk to Robinson Street and its users, which should allow for consideration of reopening once installed. Given the time-sensitive nature of the decision, staff recommend proceeding with the proposed works and recommend Council’s approval of same. ATTACHMENTS 1. Correspondence from Jonathan Dee, Cooke & Associates Consulting Engineers Ltd., re Port Burwell Lighthouse – Stabilization Concept 2. Stabilization Concept Drawing RECOMMENDATION 1. THAT Report CAO-11/23 re Stabilization Measures – Port Burwell Lighthouse be received for information; 2. AND THAT stabilization measures for the Port Burwell Lighthouse proceed as outlined in Report CAO-11/23. Respectfully Submitted by: Thomas Thayer, CMO CAO|Clerk OTTAWA, ON HAMILTON, ON 17 Fitzgerald Rd., Suite 200, K2H 9G1 jgcooke.com 52-B John St. S, Suite 200, L7R 4B6 (613) 226-8718 mailbox@jgcooke.com (289) 288-3638 John G. Cooke, P.Eng., RSW President Grazyna A. Materna, M. Eng., P.Eng Vice President John D. Barton, C.E.T. Vice President Mary Cooke, C.Tech., CSP Partner Lisa Nicol, P.Eng. Partner Marty Lockman, P.Eng., ing. Partner Jonathan Dee, P. Eng., ing. (Hamilton) Associate Chris Vopni, P.Eng. Associate a+LiNK Architecture Inc. February 1, 2023 126 Wellington Rd. London, ON N6C 4M8 Project No. 23065 Attn: Mr. Tim Finch (timf@aLiNKarch.ca) Re: Port Burwell Lighthouse Stabilization Concept Dear Mr. Finch, Further to the request from Thomas Thayer during our January 31, 2023 meeting, we are providing the following narrative about the design approach and intent for the stabilization of the Port Burwell Lighthouse, for the purposes of Thomas’ discussion with Council. A concept sketch was circulated previously. During the course of investigation of the Port Burwell Lighthouse, extensive deterioration (rot) was identified at the main columns at each corner of the lighthouse, near the top of the concrete foundation wall. The degree of deterioration is such that the capacity of these columns is seriously affected (with over 80% section loss in some cases). The lighthouse is a tall, slender structure and is subjected to significant wind loading, especially as it sits atop a rise adjacent to the water. Being a light, wood-framed structure, wind loadings have the potential to induce overturning about the base of the lighthouse. These would normally be resisted by additional compression in the columns on the leeward side of the building and tension in the columns on the windward side of the building. Resistance to these forces is presently compromised due to the condition of the columns. As such, and in addition to the risk of failure from gravity loads on the columns, there exists an overturning risk for the lighthouse. The purpose of the stabilization is to mitigate the risk of overturning as economically as possible, using guy- wires and a steel collar to limit the amount of lateral movement of the lighthouse, until such time as a permanent solution can be developed and constructed. While scaffolding or large supporting members would be very costly, other economical approaches were considered, mainly involving strapping along the columns and secured at the base, but were rejected due to the potential interference with future work, risks in terms of the extent of rot that may be encountered along the columns, and because of the potential failure by prying action should there be a compressive failure on the opposite side of the lighthouse. It should also be understood that the stabilization approach presented is intended to mitigate risks from overturning but does not prevent the potential failure of a column. Should a column fail, the cables would need to elongate by a significant amount (100-150mm) to become fully engaged in restraining the lighthouse, which will necessarily mean that there is some displacement or deformation of the lighthouse. Further mitigating risks of a column failure could be considered if the Owner wishes, but this would be more challenging and require a more significant intervention at additional cost. If you require any clarifications or further input, please don’t hesitate to contact the undersigned. Sincerely, JOHN G. COOKE & ASSOCIATES LTD. Jonathan Dee, P.Eng., ing., CAHP Associate JD/jd 23065/ltr_1 COPYRIGHT ALL RIGHTS RESERVED. ALL IDEAS, DESIGNS, DRAWINGS AND REPRODUCTIONS ARE THE PROPERTY OF a+LiNK ARCHITECTURE INC. AND ARE NOT BE USED OR REPRODUCED WITHOUTWRITTEN PERMISSION OF THIS OFFICE.126 WELLINGTON ROAD, LONDON ON N6C 4M8 P:519.649.0220 www.aLiNKarch.ca DATE: 2023.01.24 SCALE: 1:250 A1-1 2238Temporary Structural Stabilization Port Burwell Lighthouse Site Plan & Bldg. Section GUY-WIRE RESTRAINT CABLE AT EACH VERTEX. SET AT EQUAL ANGLES BETWEEN ADJACENT FACES. IDEALLY AT 45DEG. A 5/8" DIAMETER6x19 IWRC CLASS WIRE ROPE AS PLACEHOLDER SIZE. HELICAL PILE HOLD-DOWN AT EACH CABLE. DESIGN-SUPPLY-INSTALLED COMPONENT. MUST USE REPUTABLE INSTALLER (E.G. EBS GEOSTRUCTURAL) CABLE AT CURB SIDE IS LIMITED IN ANGLE. SPECIAL DESIGN CASE. HSS COLLAR, WITH MEMBER ALONG EACH FACE. EXTEND SLIGHTLYBEYOND VERTEX AND OFFSET VERTICALLY FOR SIMPLIFIED FIELD WELDING. HSS152x152x6.4 AS PLACEHOLDER SIZE FOR NOW. COLLAR TO BE SET AT UPPERMOST LANDING LEVEL (LEVEL OF EX. PERIMETER BEAMS). COLLAR HSS WILL BE ANCHORED TO EXT. FACE OF EX. WOOD COLUMNS AT EACH VERTEX.