A best practice from Répert’eau: Source control by disconnecting eavestroughs; ongoing communication with homeowners

Faced with the prospect of an increasing number of basement flooding incidents, Quebec City implemented a downspout disconnection program that achieved a 100% compliance rate due in large part to an awareness campaign targeting affected homeowners. The affected neighbourhood, Maizerets, is located in the Limoilou district and is over a century old. It is served by a combined sewer system that has often resulted in basement flooding during rainfall events, as many buildings upstream had their downspouts connected directly to the municipal sewer system. The area is also served by a tidal barrier designed to prevent the St. Lawrence from backing up in the municipal sewer system, but this also increases the risk of sewer backup during rain events because the system cannot drain easily.

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Understanding and Assessing Impacts

The City’s first step was to conduct several studies to identify the affected areas and determine which buildings were contributing to the problem. It found that 373 of the 623 homes with pitched roofs were illegally discharging their eavestrough water into the combined sewer system through the foundation drain, thereby overloading the system and violating municipal by-laws. The City had regulations in place prohibiting such designs, but these hookups persisted.

Identifying Actions

The majority of the connected downspouts were located on private property, which meant the City had to have the residents’ participation if it was to succeed. An important aspect of the plan was based on effective communication and citizen participation. However, this proved to be a major problem because compliance was initially quite low, and more stringent methods were necessary.

Implementation

The program went through a series of iterations as homeowner compliance progressed slowly from one communication to the next. The first step was to make downspout disconnection voluntary to enforce the existing by-law; after two summers, three letters were sent to building owners outlining why these measures were necessary and explaining that the full cost of downspout disconnection would be covered by the City. This first round achieved a compliance rate of only 25%. This was deemed insufficient because it did not comply with by-laws, and the City took the necessary steps to a) make the program mandatory, b) provide a free rain barrel to interested parties and c) initiate another round of mailings highlighting the mandatory nature of the program and its rationale. This brought compliance to 60%. A 100% compliance rate was only achieved after three years of communications, including seven letters and two brochures, as well as the involvement of markedly higher administrative levels and the shift from a voluntary measure to a mandatory measure involving fines.

Outcomes and Monitoring Progress

Under this program, the City also planned other stormwater retention measures for parking lots and public spaces such as schools. The downspout disconnection system cost $100,000, and an additional $25 million was invested to improve stormwater retention and sewer systems. The City also estimated that the downspout disconnection system reduced the required size of stormwater retention basins, saving approximately $500,000 through the construction of a smaller basin; this means that the downspout disconnection system immediately achieved a benefit-cost ratio of 5:1, not including the savings from reduced flooding.

Next Steps

Several key lessons were drawn from this project. First, it is critical that homeowners know why the program is necessary and how it benefits them. Second, communications should be sent by high-level officials. Third, one city official stated that in a similar situation, only three letters could be sent in a given year: the first outlining the problem, the by-law and the $300 fine, and a 30-day deadline for compliance; the second letter reiterating the content of the first letter and extending the 30-day deadline; and the third and final letter informing citizens that they either have to pay the fine or disconnect the downspout immediately at their own expense.

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