South Canoe Wind Farm Project, NS

 

Project Description

The South Canoe Wind Project is being developed by Nova Scotia companies, Oxford Frozen Foods and Minas Basin Pulp and Power with support from Nova Scotia Power, on the south shore of Nova Scotia. The project area is near the settlements of New Russell and Vaughan, located 25 km southwest of Windsor, Nova Scotia, on approximately 2,800 ha of land.  The project will include 34 wind turbines, each tower being 92 meters tall with 57 meter long blades, which will produce enough energy to serve approximately 32,000 homes.

Total Transport Rigging Incorporated (TTR) was awarded the contract to transport 34 Nacelle generators for the wind turbines to the South Canoe site, from the port facility in Brooklyn, Queens County. Each Nacelle generator unit has a total mass of 113 Tonnes and are to be transported by TTR’s seventeen (17)-axle self-propelled modular trailer (SPMT) pulled by a prime mover truck in an effort to reduce load effects on the highway and structures crossed. The total mass of the hauling equipment and payload for the transportation of one Nacelle generator is 194.4 tonnes and has an overall transporter length of 37.23 metres.

The proposed route to site required the Nacelle Transporter to travel across a number of highway structures owned and maintained by Nova Scotia Transportation Infrastructure Renewal (NSTIR).  Prior to issuing special move permits for the exceptional load of each generator transport, NSTIR required inspections and analysis of all affected structures which would be crossed during transport to site.

Harbourside Engineering Consultants (HEC) in consultation with NSTIR determined that there were a total of twenty one (21) structures that required crossing on the route which would require inspection and analysis. HEC was initially contracted by Total Transport Rigging Incorporated (TTR) to complete a permit load structural assessment of two large, multi-span bridges (assumed to be the most critical) as part of a Phase I study to determine the feasibility of the transport route. The two initial structures included:

  • Gold River Bridge (LUN140) - built around 1971, located in Luneburg County, Nova Scotia on Highway 103 near the town of Chester. The bridge has an overall span of 121.92 meters (three spans: 36.58m-48.77m-36.58m) consisting of four lines of continuous steel plate girders transversely spaced at equal 3.353 meter intervals;
  • LaHave River Bridge (LUN247) built around 1975, located in Luneburg County, Nova Scotia on Highway 103 near Bridgewater and was.  The bridge has an overall span of 123.14 meters (four spans: 30.48m-31.09m-31.09m-30.48m) consisting of six lines of continuous precast, pre-stressed concrete AASHTO girders, transversely spaced at equal 2.184 meter intervals.

Inspection guidelines included:

  • A “hands-on” visual inspection of elements reachable from the ground without the use of additional access (ladders, lifts). This included above deck elements, abutments, east and west ends of the side bridge spans and base of the two piers;
  • A limited visual inspection of the remaining pier elements, underside of deck, girders and transverse diaphragms using binoculars;
  • Photographs of observed structural defects & general site photos.

As identification of performance deficiencies was a key objective during the condition survey, any element that appeared to be damaged in such a way so as to affect its structural capacity was identified as a suspected performance deficiency.

It was determined that the two initial structures analyzed in Phase I were adequate for the crossing of the Nacelle transporter providing a number of conditions were followed including low, constant speeds and specific transverse positioning of the transporter during the crossing. Following the approval by HEC for the crossing of the transporter vehicle on the initial two structures, the inspection and analysis of the remaining nineteen structures was awarded to HEC by TTR in subsequent Phases II & III. The remaining structures included single and multi-span steel girder structures, several single and multi-span AASHTO girder structures, single and multi-span concrete box culvert structures and one timber bridge structure. In general, structural drawings we available for the majority of the bridges, but were unavailable for all box culverts and the timber structure.

A visual inspection of each remaining bridge was then completed by HEC, guidelines for each was as noted above. The purpose of the bridge inspections was to verify the geometry of the structures provided on the original design drawings when available, determine as-built geometry when drawing were not available and to identify any defects that may affect the structural capacity of bridge elements.

The analyses completed on all structures were in accordance with CHBDC CAN/CSA S6-06 (S6) Section 14 Evaluation and was based on the results of site inspections. The analysis was limited to ultimate limit state strength checks for multiple bridge crossings of the provided permit overload condition(s) for a single year. The analysis of the structures focused on several bridge components, including: surcharging of abutments & wingwalls, reinforced concrete bridge deck, girders and main longitudinal elements, transverse diaphragms, abutment piles and pier piles. Refined analysis methods were required in order to determine the global response of several structures as well as the load effects in each component of each bridge. Analysis included the development of 3D finite element models, utilizing internal transverse diaphragms and the bridge deck to partially / appropriately distribute the transport vehicle loads to as many girders as possible in an effort to decrease load effects. Cracked and uncracked stiffness properties of the girders (precast AASHTO girder structures) were used when applicable, deck and diaphragms were modeled to ensure that the most accurate load distribution was captured both longitudinally and transversely.

Following the analysis, all of the concrete box culverts to be crossed (seven total) and the 1 timber bridge structure were found to be overstressed, mainly on account of the condition of structural elements observed during the site visits and due to conservative analysis assumptions for material properties and reinforcing resulting from the absence of structural drawings. All seven (7) culverts were identified to require coring of concrete (concrete condition and compressive strength assessments to be completed from the resulting cores) and GPR (Ground Penetrating Rebar) testing to determine reinforcing steel spacing, sizes and cover to reinforcement.

The results of the testing was used to complete the refined analysis for each culvert, for which three (3) of the seven (7) culverts were determined to be structurally adequate to support the transporter vehicle loads. The remaining four (4) culvert structures were found to be inadequate to support the applied loads and required additional temporary shoring posts to be installed for resisting the additional applied loads of the transporter vehicle.

Due to the condition of the timber bridge, NSTIR determined that a full replacement of the timber superstructure was the most cost effective solution long term. HEC then completed a structural review of the Department’s Standard Timber Bridge drawings to confirm the structural adequacy for the Nacelle transporter vehicle.  South Canoe then cost shared with NSTIR in replacing the timber superstructure for which the work was completed in two weeks by NSTIR work crews.

As a result of HEC’s analysis and recommendations for temporary supports for 4 culvert structures, travel conditions were specified to allow the crossing of each structure by the Nacelle transporter.  Special move permits were issued by NSTIR for the Nacelle transporter moves, for which the first move was completed on October 6, 2014.

Client: Total Transport Riggins Incorporated

Value: $250 M (total project value)

Year: 2014

Role: Overload Transport Inspection and Analysis