APPENDIX A HERITAGE IMPACT ASSESSMENT REPORT October 9, 2015 HERITAGE IMPACT ASSESSMENT Holt Line Bridge (Duthill Bridge/10th Concession Bridge) Spanning the Sydenham River, St. Clair Township, Ontario Submitted to: Kelly Vader, MCIP, RPP BM Ross and Associates Limited 62 North Street Goderich, ON N7A 2TA Report Number: 1534665-R01 Distribution: 1 Copy - BM Ross and Associates Limited REPORT 1 Copy - Golder Associates Ltd. HIA - HOLT LINE BRIDGE - TOWNSHIP OF ST. CLAIR Executive Summary Golder Associates Ltd. was retained by B.M. Ross and Associates Ltd. (B.M. Ross) to undertake a Heritage Impact Assessment (HIA) for the proposed rehabilitation or replacement of the of the Duthill Bridge, also known as the Holt Line Bridge, located on Holt Line in the Township of St. Clair, Ontario. The objective of the HIA was to determine whether the structure represented a built heritage resource or a part of a cultural heritage landscape of cultural heritage value or interest. The analysis of the Duthill Bridge was guided by the Ontario Ministry of Tourism, Culture, and Sport’s (MTCS) Ontario Heritage Toolkit: Heritage Resources in the Land Use Planning Process. This HIA makes the following recommendations: Subject to the confirmation of preferred alternatives for the potential rehabilitation or replacement of the Duthill Bridge, St. Clair Township should consider the mitigation options identified in Section 5.3 of this report to evaluate the potential options that would conserve the cultural heritage value of the bridge. From a best practice standpoint for the conservation of heritage resources, the preferred alternative for the Duthill Bridge would be one of the following three options: Construction of a new bridge adjacent to the existing structure: The retention of the bridge in situ as a part of a pedestrian or recreational vehicle crossing would act as a form of mitigation. Rehabilitation/restoration of the existing bridge: The retention of the bridge in situ as a part of a continued vehicle crossing would act as a form of mitigation. Integration of the bridge into a new bridge: This would result in the construction of a new bridge while integrating design elements, such as the retention of some of the steel truss components of the bridge. The integration of the steel truss elements, if integrated successfully, would conserve the heritage attributes and thus, the cultural heritage value of the bridge. October 9, 2015 Report No. 1534665-R01 HIA - HOLT LINE BRIDGE - TOWNSHIP OF ST. CLAIR Project Personnel Project Director Carla Parslow, Ph.D., Associate, Senior Archaeologist Project Manager Michael Greguol, M.A., CAHP Intern, Cultural Heritage Specialist Historic Research Michael Greguol, M.A., CAHP Intern, Cultural Heritage Specialist Report Production Michael Greguol, M.A., CAHP Intern, Cultural Heritage Specialist Liz Yildiz, Administrative Assistant Senior Review Carla Parslow, Ph.D., Associate, Senior Archaeologist Acknowledgments B.M. Ross Kelly Vader, MCIP, RPP Township of St.Clair Matt Deline, P.Eng., Director of Public Works Lambton County Archives Dana Thorne, Archivist October 9, 2015 Report No. 1534665-R01 HIA - HOLT LINE BRIDGE - TOWNSHIP OF ST. CLAIR Table of Contents 1.0 STUDY PURPOSE AND METHOD .................................................................................................................................. 1 1.1 Study Process ..................................................................................................................................................... 1 1.2 Study Method ...................................................................................................................................................... 1 1.3 Technical Note ..................................................................................................................................................... 1 2.0 BACKGROUND HISTORY ............................................................................................................................................... 4 2.1 Natural Environment ............................................................................................................................................ 4 2.1.1 Historical Context ........................................................................................................................................... 5 2.2 Bridge Building Context ....................................................................................................................................... 5 2.3 Duthill Bridge History ........................................................................................................................................... 6 3.0 SITE DESCRIPTION ....................................................................................................................................................... 10 3.1 Context .............................................................................................................................................................. 10 3.2 Approaches ....................................................................................................................................................... 10 3.3 Abutments ......................................................................................................................................................... 12 3.4 Truss .................................................................................................................................................................. 12 3.5 Deck .................................................................................................................................................................. 17 3.6 Cultural Landscape ............................................................................................................................................ 17 4.0 EVALUATION ................................................................................................................................................................. 19 4.1 Ontario Regulation 9/06 ..................................................................................................................................... 19 4.1.1 Cultural Heritage Value ................................................................................................................................ 20 4.1.1.1 Design/Physical Value .............................................................................................................................. 20 4.1.1.2 Historic/Associative Value ........................................................................................................................ 20 4.1.1.3 Contextual Value ...................................................................................................................................... 21 4.1.2 Statement of Cultural Heritage Value ........................................................................................................... 21 4.1.3 Heritage Attributes ....................................................................................................................................... 21 5.0 ASSESSMENT ............................................................................................................................................................... 22 5.1 Proposed Undertaking ....................................................................................................................................... 22 5.2 Potential Impacts ............................................................................................................................................... 22 5.3 Potential Mitigation Options ............................................................................................................................... 23 October 9, 2015 Report No. 1534665-R01 i HIA - HOLT LINE BRIDGE - TOWNSHIP OF ST. CLAIR 6.0 RECOMMENDATIONS ................................................................................................................................................... 24 7.0 SOURCES ...................................................................................................................................................................... 25 8.0 IMPORTANT INFORMATION AND LIMITATIONS OF THIS REPORT ......................................................................... 26 9.0 CLOSURE ....................................................................................................................................................................... 27 TABLES Table 1: Ontario Regulation 9/06 Evaluation of the Duthill Bridge ............................................................................................ 19 FIGURES Figure 1: Study Area .................................................................................................................................................................. 2 Figure 2: Site Plan ...................................................................................................................................................................... 3 PLATES Plate 1: View of Sydenham River looking south from the Duthill Bridge .................................................................................... 4 Plate 2: Double Front survey system, 1818-1829 ...................................................................................................................... 5 Plate 3: Duthill Bridge