ICM Project Underground Infrastructure and Cable

Transcription

1 EB 0 00 Tab Schedule B ( pages) ICM Project Underground Infrastructure and Cable Handwell Replacement Segment (THESL)

2 EB 0 00 Tab Schedule B I EXECUTIVE SUMMARY. Project Description 0 The handwell replacement segment described in this document is required to protect the public from the potential safety risk posed by electric shocks from contact voltage. Handwells are essentially electrical junction boxes embedded in sidewalks or other pavement in which the connection is made between the secondary distribution system and street lighting or unmetered scattered loads. Owing to their location, which exposes them to corrosion from salt and water and construction damage, the handwells themselves may become a source of contact voltage and damage to the wires and connections within them may allow other equipment, such as streetlight poles to become energized. 0 There are approximately,00 handwells on the THESL system. Following the Level III emergency that THESL declared in 00 after children and pets received shocks from energized equipment, THESL began handwell replacement (See Section II, ). By the end of 0, THESL had replaced almost,00 existing handwells with new, non conducting composite handwells (See Section II, ). These replacements were concentrated in the downtown core because that is where both the number of handwells and the potential exposure to contact voltage are greatest. The segment proposed in this application is to replace the remaining handwells not addressed in prior years. This segment will first target the remaining handwells in the downtown core and then replace handwells located in the surrounding areas of North York, East York, York, Etobicoke, and Scarborough. By the end of 0, when this segment is complete, some 0 percent of handwells in the City of Toronto are expected to have been replaced. The handwells that remain to be replaced are primarily located in areas where City moratoriums prevent THESL from excavating the sidewalks or other pavement. 0 The following Table summarizes the cost of the segment.

3 EB 0 00 Tab Schedule B Table : Summary of Segment Costs Project Estimate Project Title Year Cost Estimate Number ($M) 0 Handwell Standardization and 0 $.0 Remediation 00 Handwell Standardization and 0 $. Remediation 0 Handwell Standardization and 0 $. Remediation Total: $.. Why the Project is Needed Now 0 Handwells are among the top three structures with the highest number of contact voltage hits as assessed by mobile scanning inspections (See Section III). Common causes include damage from the elements, as handwells are exposed to harsh environmental conditions, third party damage whenever the sidewalk is rebuilt or repaired, degradation of cable insulation, and substandard installation of connections. If left untreated, the public may be exposed to the potential safety risk posed by electric shock through contact voltage from the following sources: Contact of exposed conductor with metallic plates and covers; Direct contact with exposed conductor; or Indirect contact through another medium o Concrete structures (including sidewalks) o Conductive salt water saturates concrete and a voltage gradient forms o Metallic poles

4 EB 0 00 Tab Schedule B. Why the Project is the Preferred Alternative 0 Two options were evaluated to mitigate the potential safety risk associated with contact voltage: (a) Reactive Take no action and respond to contact voltage incidents. (b) Proactive Replace metal handwells with non conductive handwells. Replacements are prioritized to address the high risk areas based on proximity to the downtown core, where the majority of handwells are located (and thus where the majority of contact voltage occurrences on handwells are located), and where there is a high volume of pedestrian traffic. Proactive replacement of handwells is the preferred option as this approach will mitigate the existing public safety hazard. If the segment is not implemented, the risk of contact voltage will continue at current levels until such time as this work can be done.

5 EB 0 00 Tab Schedule B II PROJECT DESCRIPTION. Overview This segment addresses the immediate need for spending to address replacement of most handwells remaining on THESL s system. Handwells are essentially electrical junction boxes embedded in sidewalks or other pavement in which the connection is made between the secondary distribution system and street lighting or unmetered scattered loads. This segment addresses handwells whose replacement has not been funded in prior years. 0 The objective of this segment is to mitigate the potential contact voltage risk posed by the metallic handwells by replacing existing handwells with new handwells built to current standards. As discussed more fully below, this work will include installation of composite polymer concrete units, non conductive lids, gel connectors, and PVC jacketed cable. 0 Handwells are typically found in pre amalgamation Toronto, as well as dense mixed use areas in other parts of the city (e.g., downtown North York or the Etobicoke core). The secondary bus is run through ducts from handwell to handwell. In each handwell, the cable used to service the streetlight or unmetered scattered load is connected to the bus. A handwell is typically installed adjacent to each individual street lighting pole. Corrosion and other factors can cause a handwell to become energized, leading to potential contact voltage incidents.. Handwells and Contact Voltage Contact voltage is an intermittent condition when electricity or voltage is present on street equipment. Secondary electrical plant installed in the field is constantly subjected to environmental factors and susceptible to third party damage whenever the sidewalk is rebuilt or repaired. It endures water, salt and contamination ingress and wide variations in temperature. Secondary infrastructure refers to the low voltage electrical plant supplying 0/0V single phase, and 0/0V and 00/V three phase service. Secondary supply is sourced from overhead or underground mains and feeds loads ranging from residential and commercial customers to unmetered scattered loads such as bus shelters, traffic signals, and Business Improvement Area signs, and Street Lighting circuits.

6 EB 0 00 Tab Schedule B Before 00, most shocks from utility infrastructure around the world were treated as isolated incidents. Focus on the issue was heightened in 00, however, when a woman in New York City was fatally shocked after falling onto an energized metal service box cover. This fatality increased scrutiny from the public and regulators and triggered a wide scale awareness of contact voltage issues. In February 00, Toronto Hydro declared a Level III Emergency after of one dog was fatally shocked in November 00, and children and another dog received shocks in early 00. As a result, Toronto Hydro made a decision to inspect and make safe all handwells and handholes in Toronto. 0 As shown in Figure, handwells and the wiring within them can corrode due to age and environmental factors. Handwell covers can also corrode (See Figure a, below). This corrosion and degradation of components eventually causes the integrity of the connections to deteriorate to the extent that live electrical wires become exposed. This can create a potential safety risk to the public, such as those that led THESL to develop and implement an emergency management plan, internally known as the Level III Emergency response. Figure Open Handwell Photographed During Inspections

7 EB 0 00 Tab Schedule B THESL proposes replacing existing handwells with new non conductive handwells and lids. The conductive metal covers still found on many handwells are shown in Figure a. In THESL s proposal, these conductive lids will be replaced with the non conductive lids and composite handwells as shown in Figure b. Figure a Metal Handwell Lids Figure b Non Conductive Lids and Composite Handwell

8 EB 0 00 Tab Schedule B Figure Degraded Conditions of Split Bolt Connectors in Handwells Figure shows an exposed connection of a split bolt connecter wrapped in layers of poly vinyl chloride (PVC) tape and self amalgamative plastic (SAP). Specific procedures have been defined on the amount of PVC and SAP tape required, however this leaves room for human error if not wrapped according to the approved standard and can result in connections with insufficient insulation. Figure displays the new gel connectors introduced to prevent the seepage of water and other contaminants thus eliminating the need for the taped split bolt connections.

9 EB 0 00 Tab Schedule B Figure New Handwell Connectors Figure Repaired Cable Figure shows a damaged bus cable that has been repaired with PVC and SAP tape. For improved insulation, the bus cable specifications have been revised to require a double insulation cable with a PVC jacket instead of the single insulation cable used previously.

10 EB 0 00 Tab Schedule B III NEED Despite the work done in response to the 00 Level III Emergency (during which time THESL undertook a comprehensive city wide handwell inspection program), contact voltage remains an issue for pedestrians and pets in the City of Toronto. Contact voltage is most likely to occur in wet, icy, and salty conditions. The potential risk of contact voltage typically occurs in the winter and early spring, when salt is used most and when there is great deal of moisture and other contamination penetrating the handwells. 0 Since the Level III Emergency, THESL has launched a number of initiatives to prevent contact voltage incidents. These include: Adopting designs that no longer include handwells for new installations. Introducing new materials to combat environmental stresses including gel connectors, polymeric concrete handwells, and non conductive handwell lids. Revising Construction Standards to require new materials. Developing Standard Practices for crews to follow when conducting maintenance on connections in handwells to mitigate the risk of these assets becoming energized. Developing Standard Practice for classifying and addressing contact voltage occurrences identified through mobile surveying. 0 To further reduce the risk of contact voltage, THESL must also undertake the replacement of metal handwells proposed here. There have been a number of incidents and data to support the potential safety risks that handwells present. Since 00, THESL has been classifying and addressing contact voltage occurrences proactively identified through mobile surveying, which is performed by an external contractor. Figure shows that the number of scanned contact voltage hits has decreased each year since 00, while Figure shows that since 00, the average level of contact voltage detected has decreased by 0%.

11 EB 0 00 Tab Schedule B Figure Historical Contact Voltage Hits Identified by Mobile Surveying Figure Average Level of Contact Voltage Detected Figure shows traffic lights, handwells and street lights among the top three sources of contact voltage hits. 0

12 EB 0 00 Tab Schedule B Number of Contact Voltage Hits by Asset in 0 Figure 0 Results by Asset Class Additionally, Table shows the number of energized (greater than volt) handwells detected in THESL s service territory. Table Number of Energized Handwells Year Three of Energized Handwells Detected (> Volt) 00 (Note: scanning commenced partway through 00) 00, 0, 0 (Note: includes results up to the end of March 0) Any contact voltage occurrences that are not proactively detected through mobile scanning have the potential to harm members of the public. In 0, there were eight recorded handwell

13 EB 0 00 Tab Schedule B contact voltage incidents which resulted in claims against THESL. These incidents are listed in Table. Table Contact Voltage Incidents on Handwells (0) Date Location Description of Incident January Wellesley/Bay Dog shocked January Bay/Elm Dog shocked January Yonge/St. Clair Dog shocked January York/King/Wellington Person shocked February Danforth Avenue Dog shocked March Eglinton/Scarlett Dog and person shocked March Danforth Avenue Dog shocked August McGill Dog shocked

14 EB 0 00 Tab Schedule B IV PREFERRED ALTERNATIVE. Project Description The Handwell Replacement program will replace the above components which were installed based on previous standards with new components meeting the current standards. This work is intended to enhance public safety by mitigating the potential risk of contact voltage through ongoing handwell replacements. This approach is preferred, as opposed to deferring the required work to some later date and not mitigating potential safety risks. 0 This work begins by addressing the highest risk areas in the downtown core due to higher pedestrian traffic and a greater number of handwells with a resulting concentration of contact voltage occurrences. THESL will then begin replacement in other areas of the City with handwells that are identified as not being constructed to current standards. The cost of this approach is an estimated $. million to remediate about,00 handwells. This is expected to result in replacement of the vast majority of metal handwells, thereby reducing the potential safety risk of contact voltage to the public. 0 The alternative to the proposed replacement program would be to replace handwells reactively when specific instances of contact voltage are identified, or if they fall within the scope of a related distribution project. While this option would defer capital expenditures, it will also result in a higher potential public safety risk. As the existing handwells continue to age and the condition of the cables within them continues to deteriorate, an increase in contact voltage occurrences is expected, further compounding the risk. 0 Moreover, even if this work is deferred in the short term, the existing handwells eventually will require replacement due to their deteriorated condition. Reactive replacement costs may also be higher for locations identified during contact voltage scans due to the costs of after hours work and delays in permitting. THESL believes that it is prudent to complete this work in the near term in order to address the potential safety risk.

15 EB 0 00 Tab Schedule B. Project Scope and Cost Handwell replacement typically involves the following tasks: Excavation and removal of legacy handwells Replacement of active handwells with non conductive units Replacement of underground secondary mains cable with a superior, dual insulation cable Remaking all connections in handwells to the current standard 0 Forecast costs are based on an average a handwell replacement cost of approximately $,00 per unit and do not include unforeseen locations requiring remediation. Table : Handwells Summary of Project Costs Project Estimate Project Title Project Year Cost Estimate Number ($M) 0 Handwell Standardization and 0 $.0 Remediation 00 Handwell Standardization and 0 $. Remediation 0 Handwell Standardization and 0 $. Remediation Total: $.