History of the Sewage System:
Prince Rupert’s sanitary and storm sewer systems pre-date the incorporation of the City. They were officially initiated in early 1909, the same year that proper City lots were first available for purchase. The population doubled (from 1,500 to more than 3,000) that summer and construction was everywhere. The B.C. Department of Health & Welfare’s records show correspondence from the Provincial Health Inspector regarding the Prince Rupert Sewage system dating from the spring of that year and the Provincial Archives hold a petition from the Prince Rupert Citizen’s Association dated September, 1909, asking for an extension of the limited sewage network with a plan showing proposed sewers and plank roads. Most of the early sewers were constructed above ground on wood trestles as the streets and byways were generally wood plank boardwalks with little or no topography-related infrastructure yet constructed within the road allowances themselves.
The sewer systems were originally tied to the natural drainage courses with storm sewers discharging into nearby creeks and streams and the sanitary sewer pipelines following the existing gradients of ravines and their associated waterways to the closest creek and/or the ocean. In some cases, the Moresby and McClymont Creek systems for instance, large sewage mains were laid immediately adjacent to or actually within the creek bed itself. These were large diameter trunk sewer lines following the natural topography and thus conveniently serving the community that was being rapidly built up around them. While following natural gradients was certainly expedient and less costly at the time, it exposed our local salmon creeks to what were ultimately considered to be unacceptable environmental risks. However, once this system was in place, options for revision were both severely limited and expensive. It was only in the last decade that the original sanitary sewage systems have been substantially rerouted and successfully decoupled from the pattern of natural watercourses. This has been accomplished through major sewage construction projects in both the Moresby and McClymont Creek watersheds. The storm sewage works are, however, still largely tied to natural drainage.
A hybrid system of “combined” sewers was often favoured until the early 1970’s. Combined sewers take both sanitary sewage and natural runoff and transport the full combined load to the marine environment. As unpredictable weather-related flows would be problematic for future wastewater treatment plants, the use of combined sewers was discontinued almost 40 years ago and a program for separation of the two types of sewers instituted. At present, six of the ten major catchment areas are still combined. However, these are smaller catchments representing approximately 30% of Prince Rupert’s sewage flow.
The century old Prince Rupert sanitary sewer system is generally out-of-sight, out-of-mind. Originally made of wire-wound wood “staves” advertised as high quality “Canadian” Wood Pipe in the 1920s, our sanitary sewers were successively made of asbestos concrete, vitrified clay, and PVC plastic pipe. Special applications have also used ductile iron or steel. Wood stave, with its “40 year service guarantee” but higher propensity for failure, was almost completely replaced by the mid-1980s about the same time as the last septic tank was eliminated. That decade also saw the advent of sweeper and flusher/rodder trucks. One of the greatest Public Works advances in the previous 50 years, these specially equipped vehicles brought in a new era in sewer utility maintenance and repair. By the 90s, closed circuit television (CCTV) equipment complemented the flusher truck and again revolutionized sewer maintenance.
The Storm Sewer System:
Prince Rupert, having the highest rainfall in North America for a community with any significant population, has (almost by definition) a world-class storm drainage system. Consequently, anything more than localized flooding is very rare, despite rainfall intensities and durations that would be catastrophic in almost any other locality. The backbone of this system is the dendritic pattern of creeks and streams that run from the slopes of Mount Hays and Mount Oldfield to the Pacific. This is termed the “major” system. The “minor” system, of 1700 catch basins, 850 manholes, over 50 km of pipeline, and many kilometres of ditches, services the road network and provides, where viable, storm sewer connections to thousands of properties.
The major/minor nature of the storm sewer system is both a strength and a weakness. The natural major system is perfectly suited to the function it serves, primarily because of the great ability it has to absorb and transport irregular flows and the excess storage capacity it contains. The weakness comes in the minor system which is vulnerable to contamination by spills coming from the road network. These can be accidental but experience has shown that everything from petroleum products to paint has been intentionally poured down catch basins located along curb lines. Substantial fines are applicable in these cases. Reporting of this illegal activity is encouraged and some reduction of frequency has occurred over time. Unfortunately, the damage to fish-bearing water courses from these “spills” is significant. Winter road salts are also problematic in this regard and therefore subject to restriction. The advent of the modern road sweeper truck has significantly improved maintenance and also extended the life of the minor components of the storm sewer system by reducing sand and gravel blockages.
The Sanitary Sewer System:
With one small wastewater treatment plant, a dozen sewage pump stations, 1700 manholes, and 90 km of sewer mains, the Prince Rupert sewage system is sizeable. Despite grappling with an aging system, maintenance and repair crew size is 50% of what is was just a couple of decades ago. Cross-training has merged the former Water and Sewer departments and new tools such as closed circuit television (CCTV) inspection equipment have brought good returns. Additionally, the Flusher/Rodder truck keeps about 10% of our sewer mains functional until replacement is possible.
The following table shows the sewer system’s pipe line “demographic”:
|Installation||Total Length (KM)||%|
As the table above shows, more than half of the sewer main inventory is over 50 years old and almost 30% was installed over 70 years ago, using, by today’s standards, sub-par materials and workmanship. The replacement value of the entire Storm and Sanitary Sewer Network (trunk mains only) is approximately $55M.
The City’s Industrial Park Wastewater Treatment Plant (WWTP) is a “package” secondary treatment plant constructed in 1976 by the former BC Development Corporation (BCDC) and subsequently turned over to the City to maintain. It is now in significant need of refurbishment and upgrade.
Liquid Waste Management Plan:
Prior to the introduction of the Pollution Control Act passed by the Province of British Columbia in 1967, there was little environmental regulation directly governing the treatment and disposal of wastewater. In early 2000, the City of Prince Rupert’s permit for the discharge of wastewater granted under the provisions of the Waste Management Act, was amended with a new set of conditions. These requirements stipulated that the City carry out a “comprehensive discharge flow modelling program” to estimate the wastewater flow into the harbour under a range of expected conditions; as well as a “comprehensive environment monitoring program” to determine the theoretical initial dilution and secondary dispersion of the major outfall discharges and to develop a dynamic model to estimate the impact of the discharges on the harbour. These studies were done and subsequently approved upon submission to the Ministry’s Regional Waste Manager.
Additionally, the City was required to develop a plan that would consider ways to reduce the impact on the receiving environment from the City’s ten major ocean sewer outfalls and “determine the need for and timing of the installation of primary or secondary treatment facilities based on population projections, receiving environment capacity, and, where practical, public input”. To this end the City is currently undertaking the development of a Three-Stage Liquid Waste Management Plan (LWMP) to help ensure the long-term protection of both human health and the environment.
The LWMP is to provide a local strategy for the management of liquid wastewater (storm drainage and sanitary sewer) for planning periods of between 20 and 40 years. It is an extremely comprehensive process that includes technical and local advisory committees, regular public input, and substantial research. Completed stages must be approved by both Prince Rupert City Council and the Provincial Ministry of the Environment.