The Town of Mahone Bay is seeking proposals from qualified proponents to undertake a hydrological and hydraulic assessment of a defined study area along Ernst Brook, located in Mahone Bay, NS, using recent LiDAR data and modelling software (Stage 1). The study area will extend from Ernst Brook’s intercept with the bridge on Kinburn Street, Mahone Bay to the outlet just past the bridge on Main Street, Mahone Bay. 

Based on these assessments, which will be presented to Council as a formal report including identified options for stormwater management, the Town will then seek to identify designs within a municipal park (which is part of this larger system) that could help to retain and slow the flow of water during an extreme weather event, like a 1–100-year storm (Stage 2), while maximizing co-benefits; once these options have been identified they will be presented to the public for their input, resulting in development of a pre-design concept.

Proponents are asked to cost out Stages 1 and 2, with Stage 2 being understood as optional subject to Council's approval of one or more identified options from Stage 1 to move ahead to concept design.

Project Background

Ernst Brook is a watercourse that runs through the town of Mahone Bay, NS. This watercourse has been a topic of concern for residents of Mahone Bay for many years, as it often reaches capacity during storms and causes flooding of the surrounding area. 

Some preliminary analysis regarding Ernst Brook, undertaken by the engineering firm CBCL in 2015/16, shows that there are widespread flooding risks throughout the town. Flood risks along Ernst Brook include Town infrastructure, private residences and commercial buildings. In the CBCL report, Mahone Harbour Flood Prevention and Shoreline Enhancement Plan, a municipally-owned pond was identified in the section Design of Stormwater Management Infrastructure. The pond is in Jubilee Park, a municipal asset, located at 6 Pond Street, Mahone Bay, NS. The pond’s outlet flows into Ernst Brook. 

Scopes of Work/Services Description

The Town of Mahone Bay requires the services of a qualified firm to undertake a hydrological and hydraulic analysis of a section of Ernst Brook, Mahone Bay, NS to further understand current and future flooding risks and options to mitigate these. 

The study area will extend from the Ernst Brook intercept with the bridge on Kinburn Street, to the outlet just past the bridge on Main Street. (where the Ernst Brook transitions to being tidally influenced) 

While the 2016 CBCL study did a high-level view of a larger section of Ernst Brook, this study will focus on the water that is entering the brook between these two points, with a focus on the water coming from Jubilee Pond but also taking into consideration water entering the brook that originates from above Wye Street (see Appendix A), as the Town is wanting to get a better understanding of the movement of water in this area as well as its impact on the surrounding area and structures. 

Water from Jubilee Pond enters the outlet pipe which then passes under a gravel lane, follows an open channel, goes into a culvert under Clairmont St and then follows another open channel into Ernst Brook. There is a wooded wetland area upstream of Jubilee Pond which collects water from a large area of town including stormwater runoff from streets and recreational areas.

The purpose of the study is to (1) quantify the amount of water coming from these various sources during extreme weather events, (2) determine what impact that will have downstream, and then (3) identify options to manage the stormwater on municipally owned land (PID 60373503) and potentially nearby properties in coordination with their owners.

It is the Town's expectation that the selected consultant will complete Stage 1 of the project as defined herein and receive direction from Council concerning acceptable stormwater management options for identified properties, prior to moving forward with Stage 2 on receiving written approval from the Town.

The Services shall include the following: 

Stage 1

A hydrologic and hydraulic analysis for the study area, presented in a formal report.

1. Analysis shall use current LiDAR mapping data. A topographic survey of the water course should also be completed to improve model accuracy. 
   1. Analysis shall determine extreme flow conditions from simulations for 1 in 20-year (5% annual exceedance probability (“AEP”) and 1 in 100-year (1% AEP) flood extents in the study area under current and projected climate change conditions. 
   2. Report shall include notable flood extents under 1 in 20-year (5% AEP) and 1 in 100-year (1% AEP) events identifying the most impacted properties within the study area. 
   3. The report shall include preliminary stormwater design analysis with available storage volumes for sections of the brook and tributaries. As well as the available storage volume for the Jubilee Park property (PID 60373503), as well as the flow rate required to keep the brook from flooding, in both tributaries as well as the main brook. The goal would be to take pressure off the infrastructure further downstream by retaining and slowing the water down on the Jubilee Park property (and potentially neighboring properties particularly those located between the pond and Ernst Brook).
   4. Report to identify various options for stormwater management / detention which will allow the Town to select options for a project to move forward with. Some of these options may include constructing berms or other structures to contain water, upgrading hydraulic structures like outlet pipes and culverts to reduce risk in specific areas, expanding, enhancing or restoring wetland ecosystems, creating other ponds and/or channels that maximize the storage capacity of the park and slow the water down. 

Stage 2 (optional, dependent on the results of Stage 1)

A detailed report on selected options. Analysis of options will consider environmental, social and economic factors. The options analysis will also consider the addition and/or configuration of recreational assets in the reconfiguration of the space (PID 60373503). Options to maximize recreational / environmental co-benefits to the community; as an example, the current pond, which was created many years ago as a skating area, is no longer suitable for this purpose but perhaps a different skating structure could be incorporated into the final design. The project may also consider the adjacent properties identified in Stage 1 in the project design. 

We are looking for a concept pre-design (should identify impacts on each property, potential need to incorporate adjacent properties)

1. Engineered drawings (if applicable)
2. Environmental review 
3. Implementation roadmap
   1. Implementation steps
   2. Staff responsibilities
   3. Timelines
   4. Financial planning 

We are also looking for 2-3 public engagement sessions to be facilitated by the proponent to present the various options and get feedback from relevant stakeholders. There is a suitable Town facility which can be used for these sessions and Town staff will organize snacks and refreshments. 

Project Schedule

The deadline for all services, including invoicing, is October 2^nd, 2026. 

Additional Documents

There are documents and other materials that the Town suggests the proponents review prior to submitting a Proposal. They can be found under the Documents section.