Harward Sewer and Pump Station Upgrade

Manhole cover with the words Sanitary Sewer

To help prevent ongoing water pollution events, the City will replace and upgrade a major sewer main and pump station on Harward Street. This is part of a larger project to upgrade the City's aging sewer infrastructure using funds from a voter-approved bond in 2023.The Harward drainage area, the largest part of the Bath sewage system, consistently sees overflow problems in times when heavy rainfall outpaces the Water Pollution Control Facility's ability to pump out and treat the storm water and sewage .

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Chris,
Thank you for this question. Flooding from rain events and SLR considerations are factored into all sewer projects here in Bath. Please see your specific questions below with the associated answers.

What are the environmental design criteria for the proposed structure (level of impacts, duration of impacts, recurrence of impacts, relationship between the individual impacts (for example, the coincidence of local and remote impacts such as rainfall and tidal flooding)?

Climate resiliency has been incorporated into the design of this upgrade to better protect the Harward Street pump station’s critical infrastructure and allow the station to remain reliable during storm events. Two reports evaluated the potential impacts of climate change on the City of Bath infrastructure: the 2022 Climate Adaptation Plan by Wright-Pierce, and the 2024 Flood Vulnerability Assessment by GEI Consultants Inc. These studies identified climate hazards that threaten the Harward Street pump station and provided information to help inform upgrades to the station.
The horizontal portion of this project (gravity sewer lines in the ground) are doubled in size to allow more flow from wet weather events to travel to a pump station (Harward pump station) where it can be transported to the wastewater treatment plant for treatment. The vertical part of this project (Harward pump station upgrade) will install larger pumps at the lift station to transport more of the untreated wastewater to the treatment plant. This will help minimize pollution events caused by wet weather events. For the building itself, the City selected the design flood elevation of 11.0 ft (NAVD88) for the basis of design. The city also designed the pump station to be constructed with consideration of intermediate sea level rise projections, corresponding to year 2060. The selected design flood elevation of 11.0 is more conservative than the minimum code requirements, which will benefit the City in our desire to consider additional climate change scenarios.
What is the design life of this project?
The pump station will have an anticipated 35-year design life. The sewer lines are HDPE and have a useful life of between 50-100 years.
What is the connection, if any, between this project and the possible raising of the road elevation in this area to mitigate local flooding?
This project is independent of any future road raising considerations and would not affect this project if there is road raising in the future.
What effect will this project have on the larger drainage area issues beyond this immediate area?
The Bath sewer collection system is a combined sewer system (CSS). This means that we have relief points in the city that allow untreated wastewater to discharge into the Kennebec River during extreme flow events. This project will help minimize those occurrences.

gbrowne about 1 month ago

What are the environmental design criteria for the proposed structure (level of impacts, duration of impacts, recurrence of impacts, relationship between the individual impacts (for example, the coincidence of local and remote impacts such as rainfall and tidal flooding)?

Climate resiliency has been incorporated into the design of this upgrade to better protect the Harward Street pump station’s critical infrastructure and allow the station to remain reliable during storm events. Two reports evaluated the potential impacts of climate change on the City of Bath infrastructure: the 2022 Climate Adaptation Plan by Wright-Pierce, and the 2024 Flood Vulnerability Assessment by GEI Consultants Inc. These studies identified climate hazards that threaten the Harward Street pump station and provided information to help inform upgrades to the station. 
The horizontal portion of this project (gravity sewer lines in the ground) are doubled in size to allow more flow from wet weather events to travel to a pump station (Harward pump station) where it can be transported to the wastewater treatment plant for treatment. The vertical part of this project (Harward pump station upgrade) will install larger pumps at the lift station to transport more of the untreated wastewater to the treatment plant. This will help minimize pollution events caused by wet weather events. For the building itself, the City selected the design flood elevation of 11.0 ft (NAVD88) for the basis of design. The city also designed the pump station to be constructed with consideration of intermediate sea level rise projections, corresponding to year 2060. The selected design flood elevation of 11.0 is more conservative than the minimum code requirements, which will benefit the City in our desire to consider additional climate change scenarios. 
What is the design life of this project?
The pump station will have an anticipated 35-year design life. The sewer lines are HDPE and have a useful life of between 50-100 years. 
What is the connection, if any, between this project and the possible raising of the road elevation in this area to mitigate local flooding?
This project is independent of any future road raising considerations and would not affect this project if there is road raising in the future.
What effect will this project have on the larger drainage area issues beyond this immediate area?
The Bath sewer collection system is a combined sewer system (CSS). This means that we have relief points in the city that allow untreated wastewater to discharge into the Kennebec River during extreme flow events. This project will help minimize those occurrences.

A stormwater system in this area is subject to the stressors of local rainfall and flooding from the Kennebec River. The river flooding can have several components (rainfall floodwater propagating from upstream, high astronomical tides, storm surge from nor'easters and hurricanes downstream of Bath, and sea level rise due to climate change). All of these events come and go, with the exception of sea level rise that comes but doesn't go (it simply increases over time). Any engineering project has to account for the risk associated with each of these events.
What are the environmental design criteria for the proposed structure (level of impacts, duration of impacts, recurrence of impacts, relationship between the individual impacts (for example, the coincidence of local and remote impacts such as rainfall and tidal flooding)?
What is the design life of this project?
What is the connection, if any, between this project and the possible raising of the road elevation in this area to mitigate local flooding?
What effect will this project have on the larger drainage area issues beyond this immediate area?

Chris Miller about 1 month ago