Topic:"Infrastructure Planning" in M12746

CI Number: C0064966 Title: Tusket Tidal Pool Fish Passage Start Date: 2024/04 In-Service Date: 2026/04 Final Cost Date: 2027/05 Function: Hydro Forecast Amount: $1,763,971

AI summary The document outlines a project titled 'Tusket Tidal Pool Fish Passage' with a CI number C0064966. It specifies the start date as 2024/04, in-service date as 2026/04, final cost date as 2027/05, function as Hydro, and a forecast amount of $1,763,971.

Why do this project now? This project must be completed before the 2026 gaspereau migration season starts and large numbers of fish migrate upstream. Once the fish begin to move upstream, there will be no opportunity to perform work in the...

AI summary NS Power must complete a project before the 2026 fish migration season to prevent avoidable fish mortality, comply with DFO directives, and reduce costs. The project includes tidal pool modifications and fish entrapment mitigation, with a Final Cost Date set for May 2027. DFO requires permanent solutions to address risks identified after a 2023 mortality event.

Why do this project this way? NS Power engaged Wood Canada through a competitive procurement process to perform an investigation of the site and provide design alternatives to mitigate the issue. The report completed by Wood Canada in 2023...

AI summary NS Power selected Option A-2, the least-cost design alternative from Wood Canada's 2023 report, to remediate a tidally influenced pool. The solution raises a berm, restricts fish access to a single entrance, and installs a timber crib and piping system to maintain water levels and ensure fish survival during low tides, following discussions with environmental services and the Mi'kmaq of Nova Scotia.

Reason for Variance The increase of $448,476 from the 2026 ACE Plan subsequent submittal estimate of $1,315,495 is due to changes in the final design compared to the conceptual design. The preliminary design included 6 cfs of water flow ro...

AI summary The $448,476 increase in the 2026 ACE Plan's cost stems from design changes to avoid archaeological sites, requiring rerouting water flow from the powerhouse. This necessitated additional construction, materials, and higher-than-estimated RFP costs.

REDACTED CI C0064966 Page 4 of 6 Title: Tusket Tidal Pool Fish Passa cution Year: 2024 - 2026 age . Supervision Construction Labour

AI summary The document discusses a fish passage project at Tusket Tidal Pool, with a focus on supervision and construction labour, spanning from 2024 to 2026.

Document No: XXX-XX-XXXX-XXXX Project Cost Estimate Input Checklist and Maturity Matrix Hydropower Required fields: Estimate Classification Project Name: C0064966 Tusket Tidal Pool Fish Passage Started or Preliminary Class 5 Class 4 Class...

AI summary The document presents a project cost estimate input checklist and maturity matrix for the C0064966 Tusket Tidal Pool Fish Passage hydropower project. It outlines the maturity levels of various project definition deliverables, including scope, capacity, location, technology selection, strategy, and planning.

3.1 General The concept design options presented in the following Sections were developed to meet the design criteria noted in Section 1.4. For the purposes of this report, options that prevent fish from entering the tidal pond area were d...

AI summary The document outlines design options for a tidal pond area, categorized as 'P' (preventing fish entry) or 'A' (allowing fish entry), developed to meet criteria from Section 1.4. The focus is on infrastructure planning and environmental considerations related to fish passage.

3.2.1 Description The plan and details of Option A-1 are shown on Drawing SK-002. This option consists of blocking off all the tidally influenced inflow / out flow sites along the berm on the right side of the tailrace channel, except for...

AI summary Option A-1 involves blocking tidal inflow/outflow sites along the tailrace channel's berm except for the downstream end, maintaining wetland function and fish passage. The single entrance restricts tides, lowering water levels in the tidal pond. Swamp mats are used for construction access on adjacent wetlands.

3.3.1 Description The plan and details of Option A-2 are shown on Drawing SK-003. As in Option A-1, this option consists of blocking off all the tidally influenced inflow / out flow sites along the berm on the right side of the tailrace ch...

AI summary Option A-2 involves blocking tidal inflow/outflow sites on a dam's berm, except for a downstream outlet, to maintain fish passage and water levels. A 6 cfs flow is sustained via pump or conduit, resizing the outlet to ensure adequate depth for fish movement during low tides. Swamp mats are proposed for construction access.

3.3.2 Capital Cost Estimate and Construction Schedule The estimated capital cost (Class 5 estimate) of Option A-2 is $340,000. The work can be executed between January, 2024 and spring 2024.

AI summary The estimated capital cost (Class 5 estimate) of Option A-2 is $340,000, with construction scheduled between January 2024 and spring 2024. The timeline and cost are presented as key details for the project's implementation phase.

3.4.1 Description The plan and details of Option A-3 are shown on Drawing SK-004. This option consists of closing off all tidally influenced inflows to the tidal pond area, except at the most downstream end, by constructing a berm in the w...

AI summary Option A-3 involves constructing a berm to restrict tidal inflows, maintaining a 6 cfs flow for fish oxygenation and migration, resizing outlets for suitable water depth, and using swamp mats for construction access. This differs from Option A-2 by extending the berm's length and height.

3.4.3 Drawings The drawing for Option A-3 is provided on the following page. 3.5 Option A-4: Same as Option A-3, Except Provide Additional Entrance to Existing Fishway to Provide Upstream Passage Out of the Tidal Pond

AI summary The section describes the drawings for Option A-3 and Option A-4, which is similar to A-3 but includes an additional entrance to an existing fishway to enhance upstream passage from the tidal pond.

3.5.1 Description The plan and details of Option A-4 are shown on Drawing SK-005. This option is similar to Option A-3 and consists of closing off all tidally influenced inflows to the tidal pond area, except at the most downstream end, by...

AI summary Option A-4 involves constructing a berm to restrict tidal inflows, modifying a fishway with an additional 6 cfs flow during gaspereau migration, and resizing outlets to maintain water depth for fish movement. Swamp mats are proposed for construction access on wetlands.

3.5.2 Capital Cost Estimate and Construction Schedule The estimated capital cost (Class 5 estimate) of Option A-4 is $1,100,000. It will be extremely challenging to execute the work between January, 2024 and spring 2024.

AI summary The estimated capital cost for Option A-4 is $1,100,000, with significant challenges anticipated in executing the project between January 2024 and spring 2024 due to the tight timeline.

3.8 Option P-1: Block All Inflow to Tidal Pond to Unusual High-Water Levels, and Place Hung Culvert with an Aboiteau Gate on Downstream End and Raise the Berm

AI summary Option P-1 proposes blocking inflow to a tidal pond to manage high water levels, installing a hung culvert with an aboiteau gate downstream, and raising the berm. This engineering solution is part of a regulatory proceeding evaluating measures to address tidal pond management and infrastructure adjustments.

3.8.1 Description The plan and details of Option P-1 are shown on Drawing SK-007. This option consists of closing off all tidally influenced inflows to the tidal pond area, except at the most downstream end, by constructing a berm in the w...

AI summary Option P-1 involves constructing a berm to block tidal inflows into a tidal pond, maintaining wetland functions while preventing fish migration. An aboiteau will be built at the downstream outlet, requiring regular maintenance. Swamp mats will aid construction access. The design aims to manage extreme water levels and preserve ecological integrity.

3.8.2 Capital Cost Estimate and Construction Schedule The estimated capital cost (Class 5 estimate) of Option P-1 is $650,000. It will be extremely challenging to execute the work between January, 2024 and spring 2024.

AI summary Option P-1 has a Class 5 capital cost estimate of $650,000, with significant challenges anticipated in executing the project between January 2024 and spring 2024 due to timing constraints.

3.10 Option P-3: Infill the Tidal Pond Area to the Level of the Tree Line (Top of Existing Berm)

AI summary Option P-3 proposes infilling the tidal pond area to the level of the tree line (top of existing berm), likely involving environmental and regulatory considerations. The text introduces this option as part of a regulatory proceeding, though no specific arguments or impacts are detailed in the provided text.

Options A-1 and A-2 The first options A-1 and A-2 were intended to provide designs that would minimize the ecological impact to the tidal pond and wetland, minimize permitting with just a minor watercourse alteration, no HADD, no or minima...

AI summary Options A-1 and A-2 aim to minimize ecological impact on tidal ponds and wetlands, reduce permitting requirements, and address archaeological concerns. Work must be completed by April 1, 2024, due to seasonal constraints, limited access, and the need for stabilization during tidal fluctuations.

3.12 Other Options Considered 1. The option of widening the inlet / outlet by removing a length of the berm (up to 40ft long) was considered. In this option, the fish would still enter the tidal pool area as the tide rose, and move back ou...

AI summary The text evaluates engineering options for modifying a tidal pool's inlet/outlet to improve fish passage during low tide. Options include widening the berm, constructing dual outlets, or maintaining a single upstream outlet. Each approach faces challenges related to silt management, water flow adequacy, fish behavior, and environmental impacts like oxygen depletion in stagnant water.

Description Pros Cons Potential Risks No loss of trees on the berm Less disturbance to the wetland ecology or potential archaeological as there is only infill in eroding and low areas that are already disturbed areas. Mats used for access...

AI summary The text presents a comparison of options for managing tidal pond inflow, focusing on environmental and cost considerations. Option A-2 is highlighted for its lower initial capital cost and reduced ecological disturbance, though it carries risks related to erosion and fish predation.

Description Pros Cons Potential Risks construction conditions, it will be challenging. Material for siphons may have a lead time. Limits work time to low tide. Poorer quality of work and Material is readily available. No cofferdam required...

AI summary The document discusses the construction of a siphon, highlighting challenges such as material lead times, construction during low tide, and environmental risks like sediment runoff and wetland impact. Efforts to minimize environmental and archaeological impact are noted, but potential risks remain.

Description Pros Cons Potential Risks /outlets in berm and outlet channel over time or during high-water levels high tide high flow events. Additional entrance to the fishway will require cleaning, maintenance and monitoring. which needs t...

AI summary The document evaluates different options for managing water flow and fish passage in a tidal pond. Option P-1 involves blocking inflow and using a culvert with an aboiteau gate, which may prevent fish access and cause environmental concerns. It is the second most expensive option and faces constructability challenges due to tidal conditions and weather delays.

Description Pros Cons Potential Risks Cast-in-place concrete and earthworks will be required for the aboiteau (difficult during winter conditions). Poorer quality of work and increased risk of weather related construction delays. Cofferdam...

AI summary The document outlines potential construction challenges and risks related to building an aboiteau and associated earthworks, including weather-related delays, environmental impacts, and sediment runoff. It also mentions efforts to minimize the construction footprint and its effects on wetlands and wildlife.

Table 4-2: High Level Summary Matrix of Concept Design Options EVALUATION CRITERIA OPTION A-1 A-2 A-3 A-4 A-5 P-1 P-2 P-3 Fish Access and Risk of Stranding Constructability Construction Footprint Potential for Sediment Runoff Long Term Mai...

AI summary Table 4-2 presents a high-level summary matrix of concept design options, evaluating various criteria such as fish access, constructability, construction footprint, sediment runoff, long-term maintenance, and capital cost for different options labeled A-1 through A-5 and P-1 through P-3.

5.1 Conclusions - 1) There are several options and different combinations of aspects of the options presented. The choice is basically between: - a) allowing the tidal pond area to continue as a wetland with the ecological benefits that su...

AI summary The document outlines options for managing a tidal pond to prevent fish mortality due to oxygen depletion, balancing ecological benefits with infrastructure constraints, and emphasizes the need for minimal environmental impact and timely construction.

NON-CONFIDENTIAL 1 • Temporary pumping measures do not fully address deficiencies identified through data 2 collected in 2023 (bathymetry and legal land survey). Remedial works on the artificial 3 berm and southern outlet structure are sti...

AI summary Temporary pumping measures are insufficient to address deficiencies identified in 2023, requiring remedial works on the artificial berm and southern outlet structure to mitigate mortality risk.

CI C0064966 – Tusket Tidal Pool Fish Passage (NSEB M12746) NSPI Responses to Nova Scotia Energy Board Information Requests 1 Request IR-3: 22 sediment or vegetation deposits shall be identified during the weekly inspections and 23 removal...

AI summary The document outlines the expected useful life of a timber crib structure at 25 years and the need for regular debris and vegetation removal to maintain its integrity. Weekly inspections are required to identify and address sediment or vegetation deposits promptly.

CI # C0064966 Tusket Tidal Pool Fish Passage $1,763,971 This capital item was included in NS Power's 2026 ACE Plan with an estimated cost of $1,315,495, in the list of capital items for subsequent approval. In its application, NS Power not...

AI summary The Board approved a $1,763,971 capital item for the Tusket Tidal Pool Fish Passage project, which aims to mitigate fish mortality caused by hydro operations. The increase in cost from the 2026 ACE Plan was due to updated design and construction pricing. The project is necessary to address environmental obligations and prevent fish stranding.