Wastewater Treatment in Small Communities

Understanding Wastewater Treatment Challenges in Small Communities

Small communities across Atlantic Canada face unique challenges when it comes to wastewater treatment. Unlike major urban centres with dedicated infrastructure budgets and extensive municipal resources, towns and villages with populations under 5,000 must balance effective treatment with fiscal responsibility and operational simplicity. In Nova Scotia alone, approximately 60% of the population lives outside Halifax Regional Municipality, with many residents relying on small-scale municipal systems or private on-site treatment solutions.

The Maritime climate presents additional considerations that engineers must address when designing wastewater treatment systems. Cold winters with temperatures regularly dropping below -15°C affect biological treatment processes, while heavy spring runoff from snowmelt can overwhelm collection systems. Coastal communities must also consider the receiving water sensitivity, as many discharge points flow directly into the Bay of Fundy, Gulf of St. Lawrence, or Atlantic Ocean—waters that support crucial fisheries and tourism industries.

For small communities in Nova Scotia, New Brunswick, and Prince Edward Island, selecting the appropriate wastewater treatment technology requires careful analysis of population projections, seasonal fluctuations (particularly in tourist areas), available land, and long-term operational capacity. The goal is achieving regulatory compliance while minimizing capital expenditure and creating systems that local operators can effectively manage.

Regulatory Framework and Discharge Requirements

Wastewater treatment facilities in Nova Scotia must comply with both federal and provincial regulations. The Canadian Wastewater Systems Effluent Regulations (WSER), established under the Fisheries Act, set baseline national standards that apply to systems discharging to surface waters. These regulations mandate maximum concentrations of carbonaceous biochemical oxygen demand (CBOD) at 25 mg/L and total suspended solids (TSS) at 25 mg/L, measured as average monthly concentrations.

Nova Scotia Environment and Climate Change maintains additional provincial requirements through the Environment Act and associated regulations. Facilities must obtain an Approval to Operate, which may impose stricter limits based on receiving water characteristics. Communities discharging to sensitive watersheds, shellfish growing areas, or recreational waters often face enhanced treatment requirements, including:

• Total phosphorus limits of 0.5-1.0 mg/L to prevent eutrophication in freshwater bodies

• Ammonia nitrogen restrictions varying seasonally to protect aquatic life

• Fecal coliform limits of 200 CFU/100mL or lower for recreational water protection

• pH maintenance between 6.0 and 9.0

• Chlorine residual limits when chemical disinfection is employed

Small systems with design flows below 100 cubic metres per day may qualify for modified monitoring requirements, though they must still meet effluent quality standards. Understanding these regulatory nuances is essential for communities seeking to optimize their treatment approach while maintaining full compliance.

Treatment Technology Options for Small Communities

Lagoon Systems

Facultative lagoons remain one of the most common treatment methods for small Maritime communities, and for good reason. These systems require minimal mechanical equipment, have low energy consumption, and can be operated by staff without specialized certifications. A typical facultative lagoon system for a community of 1,000 people requires approximately 2-3 hectares of land and achieves treatment through natural biological processes.

In Atlantic Canada, lagoons are typically designed with extended detention times of 120-180 days to account for reduced biological activity during winter months. Multi-cell configurations with at least three cells in series improve treatment reliability and allow for maintenance without system shutdown. Capital costs generally range from $1,500 to $3,000 per person served, with operating costs of $30-60 per person annually.

However, lagoons have limitations. They struggle to meet stringent phosphorus limits without chemical addition, require significant land area, and may produce odours during spring turnover. Communities in coastal areas with limited flat land or those near residential development may need to consider alternative technologies.

Mechanical Treatment Plants

Package mechanical plants, including extended aeration, sequencing batch reactors (SBRs), and membrane bioreactors (MBRs), offer compact footprints and consistent effluent quality. An SBR system treating 200 cubic metres per day can fit within a building footprint of 150-200 square metres, making it suitable for communities with limited available land.

Extended aeration systems operate with long solids retention times (20-30 days), which reduces sludge production and simplifies solids handling. These systems can consistently achieve effluent CBOD and TSS below 10 mg/L and can be configured for nitrogen removal through modified operation cycles. Capital costs are higher than lagoons, typically $3,000-6,000 per person served, but the reduced land requirement often makes them cost-effective for communities where land values are high.

MBR technology, while more expensive, produces effluent quality suitable for water reuse applications and meets the most stringent discharge requirements. For coastal Nova Scotia communities discharging near shellfish areas, MBR systems can achieve fecal coliform levels below 14 CFU/100mL without chlorination, eliminating concerns about chlorine toxicity to marine organisms.

Natural and Hybrid Systems

Constructed wetlands and hybrid natural treatment systems offer middle-ground solutions that combine passive treatment with smaller footprints than conventional lagoons. A subsurface flow constructed wetland treats wastewater as it passes through engineered gravel beds planted with native cattails, bulrushes, or phragmites.

These systems work well as polishing stages following primary treatment, reducing nutrients and providing natural disinfection through UV exposure and predation. In the Maritime context, wetland systems must be designed with adequate depth (typically 0.6-0.9 metres) and proper insulation to maintain treatment during winter months. Hybrid systems combining vertical and horizontal flow cells can achieve year-round ammonia removal even in Nova Scotia's climate.

Design Considerations for Maritime Conditions

Engineering wastewater systems for Atlantic Canada requires specific adaptations to address regional conditions. Cold weather design is paramount, as biological treatment rates decrease significantly as temperatures drop. The van't Hoff-Arrhenius equation indicates that reaction rates roughly double for every 10°C increase in temperature; conversely, treatment efficiency can drop by 50% or more during winter months if systems are not properly designed.

Key cold-weather design strategies include:

• Oversizing biological reactors to compensate for reduced winter activity—typically increasing volume by 50-100% compared to temperate climate designs

• Installing aeration systems in mechanical plants within heated enclosures

• Burying piping below the frost line (1.2-1.5 metres in most of Nova Scotia)

• Providing supplemental heating for critical process areas

• Selecting cold-tolerant bacterial cultures for system startup

Inflow and infiltration (I/I) represents another significant challenge for Maritime communities. Older collection systems, particularly those constructed before 1970, often experience I/I rates of 30-50% during wet weather events. This additional flow dilutes wastewater strength, increases pumping costs, and can hydraulically overload treatment facilities.

A comprehensive I/I reduction program should precede or accompany any treatment plant upgrade. Techniques including smoke testing, CCTV inspection, and flow monitoring can identify problem areas. Addressing I/I often provides better value than simply upsizing treatment facilities to handle peak flows.

Operational Requirements and Capacity Building

The most sophisticated treatment system will fail without competent operation and maintenance. Small communities often struggle to attract and retain certified operators, creating a chronic challenge for system performance. Nova Scotia requires wastewater system operators to hold appropriate certification levels, ranging from Class I (small systems) to Class IV (large, complex facilities).

When designing systems for small communities, engineers should prioritize operational simplicity. This means:

• Minimizing the number of mechanical components requiring maintenance

• Selecting equipment with long service intervals and readily available parts

• Installing comprehensive SCADA systems with remote monitoring capabilities

• Providing detailed operations manuals with troubleshooting guides

• Designing for redundancy in critical systems such as pumping and aeration

Remote monitoring has become increasingly cost-effective and valuable for small community systems. Modern SCADA systems can alert operators to equipment failures, track process parameters, and even adjust operations automatically. For communities where operators are not on-site daily, these systems provide essential oversight and early warning of developing problems.

Training investments also yield significant returns. Operators who understand the biological and chemical processes occurring in their systems can anticipate problems and optimize performance. Provincial operator certification programs, supplemented by manufacturer training and mentorship from experienced operators, build the capacity needed for long-term success.

Financial Planning and Funding Opportunities

Financing wastewater infrastructure represents a substantial challenge for small communities with limited tax bases. A treatment facility upgrade costing $3 million for a community of 500 households translates to $6,000 per household—a significant burden even when amortized over 20-25 years.

Fortunately, several funding programs exist to support small community infrastructure in Atlantic Canada. The Investing in Canada Infrastructure Program (ICIP) provides federal funding for up to 40% of eligible project costs, with provincial contributions adding another 33%. This can reduce the municipal share to as little as 27% of total project costs.

The Atlantic Canada Opportunities Agency (ACOA) offers programs supporting community infrastructure, particularly in rural areas. The Federation of Canadian Municipalities Green Municipal Fund provides grants and low-interest loans for projects incorporating innovative or sustainable technologies.

Communities should also explore:

• Nova Scotia Municipal Finance Corporation financing at competitive rates

• Infrastructure Canada's Disaster Mitigation and Adaptation Fund for climate-resilient designs

• Public-private partnerships for larger regional systems

• Gas Tax Fund allocations for qualifying infrastructure projects

Early engagement with funding agencies during the planning phase helps ensure projects meet program requirements and maximizes available support. Many successful projects combine multiple funding sources to minimize the burden on local ratepayers.

Planning for the Future: Climate Adaptation and Growth

Wastewater infrastructure built today must serve communities for 50 years or more, requiring engineers to anticipate future conditions rather than simply addressing current needs. Climate projections for Atlantic Canada indicate more intense precipitation events, rising sea levels, and warmer average temperatures—all factors affecting wastewater system design and performance.

Increased precipitation intensity requires larger collection system capacity and treatment facilities capable of handling higher peak flows. Sea level rise, projected at 30-100 centimetres by 2100 along the Nova Scotia coast, threatens low-lying infrastructure and may require elevation of critical facilities or relocation of outfalls.

Warmer temperatures present a mixed picture. While biological treatment processes operate more efficiently at higher temperatures, warmer receiving waters hold less dissolved oxygen, potentially requiring higher treatment levels to protect aquatic ecosystems. Algae growth in lagoons may increase, requiring modified operating strategies.

Population trends vary significantly across Atlantic Canada, with some communities experiencing growth while others face decline. Treatment systems should incorporate flexibility—modular designs that can expand if growth occurs or scale back operations if populations decrease. This adaptability protects community investments regardless of how demographic trends unfold.

Partner with Experienced Engineering Professionals

Successful wastewater treatment projects in small communities require engineering partners who understand both technical requirements and local context. From initial planning and feasibility studies through detailed design, construction oversight, and operator training, comprehensive engineering support ensures projects deliver lasting value.

Sangster Engineering Ltd. has served communities across Nova Scotia and the Maritime region for decades, bringing practical experience in small community infrastructure to every project. Our team understands the regulatory environment, funding opportunities, and operational realities that shape successful wastewater systems in Atlantic Canada.

Whether your community is evaluating treatment options, planning system upgrades, or seeking assistance with regulatory compliance, our engineers provide the technical expertise and responsive service you need. Contact Sangster Engineering Ltd. in Amherst, Nova Scotia, to discuss how we can support your community's wastewater infrastructure needs and help you build systems that protect public health and the environment for generations to come.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.