Napanee Water Pollution Control Plant

The Napanee Water Pollution Control Plant (WPCP) was constructed in 1953 and has undergone multiple plant upgrades in 1981, 1993,2001, and 2009. The plant is owned and operated by the Town of Napanee (Town) with a rated average day flow (ADF) capacity of 9,087 m³/d. The plant currently treats an ADF of 7,148 m³/d (79% of plant capacity) of wastewater and receives hauled septage from rural communities and leachate from the local landfill. The Napanee WPCP discharges treated effluent to the Napanee River, immediate south of the plant boundaries. The Napanee WPCP was designed as a conventional activated sludge facility with preliminary, primary, secondary treatment, and chlorine disinfection to provide treatment for both municipal wastewater and industrial wastewater flows from the Town and the surrounding rural communities as well as leachate from the local landfill.

In recent years, the Town has experienced residential growth and significant inflow and infiltration (I/I) in the wastewatercollection system. The hydraulic loading to the Napanee WPCP frequently exceedsthe rated ADF, resulting in regular bypasses of the secondary treatment system, insufficient treatment unit detention times, and a lack of redundancy in key unit processes. The Town is upgrading and expanding the Napanee WPCP to address these concerns and to support future community growth.

The Town retained EVB to provide engineering servicesfor the detailed design and construction administration of the plant expansion.

The scope of upgrades included the design of:

• New Headworks Facility incorporating fine screening, screeningconveying and compacting, grit removal, grit cleaning and disposal, septagereceiving, primary flow elements, etc.
• New Intermediate Pumping Station.
• New Nereda Aerobic Granular Sludge (AGS) reactors, with fine bubblediffusers, influent distribution system, effluent weir assemblies, and solidswaste extraction system.
• Construction of new tertiary filters with all associatedappurtenances (i.e. chemical feed systems, backwash systems, etc.).
• Construction of ultraviolet disinfection channels with associated equipment.
• Construction and installation of a mechanical sludge thickening system.
• Upgrades to the anaerobic digester roofs.
• Upgrades to the biogas boiler and piping system.
• New facilities including control room and electrical room.
• Installation of new emergency standby power and new electricalservice feed.
• Instrumentation and control to integrate the new and existingsystems.

Approach and Methodology

The EVB project team first completed an extensive review of the recommendations from the 2011 Class Environmental Assessment (EA) Environmental Study Report (ESR). A comprehensive review of secondary treatment technologies was completed, and as a result, the ESR proposed secondary treatment solution of integrated fixed film activated sludge was updated to aerobic granular sludge.

Main Challenges andInnovative Solutions

The Napanee presents unique operating challenges.Specifically, the plant has:

• Hydraulic capacity frequently exceeding ADF capacity limit of 9,087 m³/d
• Significant I/Ifrom roof leaders, leaky pipes, footing drains, sump pumps, etc.
• Insufficient treatment unit detention times and lack of redundancy
• Close proximityto houses, site access / transportation routes
• Capacity andsensitivity of receiving stream
• Leachate,sludge and septage treatment storage and disposal.

The upgrades and expansion to the Napanee WPCP consist primarily of constructing a new treatment train to the west of the existing plant. The new secondary treatment process will be constructed consisting of a three train Aerobic Granular Sludge (AGS) plant.

‍