About Clearford One
Clearford One is a complete wastewater solution for the collection, conveyance and treatment of sewage. The system is built on three core products: ClearDigest smart digester tanks, ClearConvey Small Bore Sewers (SBS), and the ClearRecover optimized treatment package. Each product is fully engineered for efficiency and optimized for total system performance.
Wastewater is collected in ClearDigest tanks for pre-treatment of pollutants before the conveyance of solids-free effluent in the ClearConvey SBS gravity pipe network to the ClearRecover treatment plant for final polishing and water recovery.
This proven wastewater system provides a variety of benefits compared to other systems including improved environmental performance, lower capital and operating costs, more flexible deployment, and extended life cycle.
Clearford developed the ClearDigest and ClearConvey products, and has refined each while building a record of performance in small communities in Ontario, Canada over the past 25 years. Ontario is home to 40% of Canadians and enjoys an advanced urban society with environmental standards equal to the best in the world.
While Clearford was investing in a new method of wastewater collection and primary treatment, dramatic advances were being made by others in final treatment technologies. Membrane bioreactor (MBR) systems have become highly effective and low-cost for secondary and tertiary wastewater treatment.
However, sewage delivered through a conventional collection system requires large and costly primary treatment facilities to prepare the wastewater for final MBR treatment. Improved quality of effluent was achieved but total capital and operating costs were even higher than before.
Clearford One was introduced in 2015 with the first installation commissioned a year later at Fetherston Park in Ontario. It combines ClearDigest and ClearConvey with ClearRecover final treatment and disinfection by Clearford Crossfire® ultraviolet technology. ClearRecover is a packaged system ranging from MBR plants to constructed wetlands, designed and manufactured by the Clearford Treatment Technologies division.
The capital cost of Clearford One is approximately 50% lower than a conventional system with operating and maintenance cost also 50% lower.
How It Works
Clearford One delivers a better approach to wastewater servicing. The key to enabling the efficiencies of Clearford One is on-site removal of sewage solids and digestion of organic pollutants in ClearDigest smart digester tanks.
ClearDigest removes solids at the source, performing primary and partial secondary treatment before releasing liquid effluent to the ClearConvey pipe network. Solids are digested to greatly reduce the volume of organic material and hydraulic loading. ClearDigest is only pumped out after decades of normal use.
ClearConvey is a network of small bore sewer pipes that carries liquids without any infiltration to an optimized facility for final treatment. Reduced contaminants in the liquid effluent allow for more efficient recovery of clean water using the ClearRecover treatment package.
ClearRecover is a treatment facility right-sized to match the reduced hydraulic loading and effluent characteristics from ClearDigest. It can take different forms depending on local conditions and project requirements, ranging from membrane bioreactor (MBR) to constructed wetland.
ClearDigest smart digesters are underground tanks that receive raw sewage from each connected source. ClearDigest tanks retain the solids, decompose the biosolids, modulate the flow, and release solids-free effluent by gravity to the ClearConvey pipe network. A proprietary inlet device uses the kinetic energy of the inflow to gently mix sewage in the tank to enhance digestion. A patented outlet device allows the water level in the tank to increase during peak use while restricting the outflow from the tank to a modulated rate.
ClearDigest effectively performs all of the primary treatment (settling) and much of the secondary (biological) treatment, reliably removing 75% of suspended solids and 65% of biochemical oxygen demand (BOD) from raw sewage. The liquid effluent from ClearDigest is substantially solids-free with consistently lower pollutant levels than raw sewage. This enables the efficient conveyance of liquid effluent in ClearConvey small bore sewers, and significantly simplifies treatment operations at the ClearRecover treatment plant.
Furthermore, the effect of modulating the flow is significant—it reduces the need to oversize downstream collection and treatment infrastructure by as much as 50% compared to conventional sewage systems. The result is smaller pumps, smaller tankage, and smaller footprint for wastewater infrastructure. Flow modulation also normalizes pollutant loading in the liquid effluent and eliminates shock loading to the treatment plant. This allows the final optimized treatment package to target the specific effluent character for efficient treatment.
While ClearDigest is highly efficient at decomposing biosolids in raw sewage, non-biodegradable solids are left to accumulate in the smart digesters. The tanks require pumping only after decades of normal use. For this frequency of maintenance, the life-cycle cost for operating the Clearford One system is minimized.
ClearConvey is a small bore sewer (SBS) system tailored specifically for the efficient conveyance of liquid effluent from ClearDigest smart digesters. Since the liquid effluent is substantially solids-free, SBS pipes are optimized for flow conveyance rather than solids carrying. ClearConvey uses small diameter pipes that can be laid with very low and variable slope. The use of flexible plastic pipe allows for streamlined flow in the sewer network, and there is no need for large manholes for maintenance access.
Whereas conventional sewers need large pipes to accommodate sewage solids and peak flow, ClearConvey uses substantially smaller pipes—in cases, three times smaller than conventional sewers. This is because ClearDigest smart digesters are so effective at removing solids and modulating the flow.
ClearConvey relies on gravity to move liquid effluent through the SBS pipe network. However, the pipe slope requirement is reduced by up to 50% compared to conventional sewers because ClearConvey is not required to move large solids down the sewer pipe. When wastewater pumping is required, ClearConvey may use only a third of the pump stations required in a conventional system. Furthermore, pumping is simplified by the use of smaller pumps that are only required to handle liquid effluent, not messy sewage solids. This reduces energy use, as well as capital and maintenance requirements.
ClearConvey uses flexible, durable high-density polyethylene (HDPE) pipes with fused joints and watertight access points that eliminate extraneous flow to the system. In conventional sewers, leaky joints in pipes and manholes are a significant cause of inflow and infiltration of groundwater that reduce the conveyance capacity of the system and add pumping and treatment costs for downstream infrastructure. Leaky joints may also allow sewage to pollute valuable soil and groundwater resources.
The ClearRecover treatment plant is optimized to take full advantage of the unique features of the Clearford One system. ClearRecover acts as a final polishing step for removing wastewater pollutants, leaving clean water that can be reused in the community or released back to the environment. The treatment facility is fully customizable to suit the site requirements for plant configuration, treatment quality and budget. Treatment requirements may be driven by local regulations, as well as the suitability of certain treatment technologies to meet local conditions for equipment supply, construction techniques, and availability of skilled workforce. Deployments of ClearRecover range from constructed wetlands to compact state-of-the-art membrane bioreactors.
The combination of ClearDigest smart digesters and ClearConvey SBS pipe network significantly reduces the hydraulic and pollutant loading to the ClearRecover treatment plant. The modulation of flow from ClearDigest greatly reduces peak hydraulic loading to the treatment plant, resulting in as much as 50% smaller equipment and tankage compared to conventional plants. Sizing is further reduced by the elimination of extraneous flow to the ClearConvey pipe network. ClearRecover fits into half the footprint of conventional treatment plants, requiring less land and reduced maintenance costs.
ClearRecover treatment operations are simplified compared to conventional plants. The wastewater needing treatment contains 75% fewer suspended solids and 65% less biochemical oxygen demand (BOD) than raw sewage because of pre-treatment in ClearDigest smart digesters. Pollutant loading is normalized to a consistent effluent character that is targeted for efficient final treatment at the ClearRecover plant. ClearRecover does not require extensive headworks and primary treatment—there are substantial capital and operating cost savings associated with elimination of screening, grit removal and primary settling. Sludge production is reduced compared with conventional plants because most of the pollutants are captured in ClearDigest smart digesters. Furthermore, biological treatment is targeted to specific pollutants such as nutrients (nitrogen, phosphorus) for more efficient use of treatment infrastructure and greater environmental protection.
ClearRecover achieves the highest quality when paired with the patented Clearford Crossfire Technology®. Treated effluent can be sterilized to non-detect pathogen levels using this highly efficient ultraviolet (UV) disinfection technology, making the effluent safe for reuse in non-potable applications such as irrigation.
Small Bore Sewers—A Proven Technology
Small bore sewers (SBS) are a well-known type of sewage collection system employed around the world for efficient wastewater servicing of communities. The technology was first postulated as early as 1935; however, the first recorded installations were implemented in the 1960s in Australia, Africa and the US.
The technology is well documented in the United Nations Development Programme and World Bank publication “The Design of Small Bore Sewer Systems” (1985). Its success has led to adoption of small bore sewer design standards in many countries, including in the US (Environmental Protection Agency, Water Environment Federation), Australia and New Zealand (Australian/New Zealand Standard National Plumbing and Drainage Code), Canada (Ontario Ministry of the Environment), and India (Central Public Health and Environmental Engineering Organisation).
Making Gravity Work for You
Clearford’s approach is to use passive gravity-driven design throughout the Clearford One system to perform the critical functions of sewage conveyance and treatment. Harnessing gravity reduces reliance on power supply, which may be expensive or unreliable, and increases the sustainability of wastewater servicing over the long-term.
Design of the ClearDigest smart digesters builds on the long established performance of traditional septic tanks, which use gravity for the separation of solids and liquids in sewage. Heavier solids sink to the bottom of the tank while lighter oils and grease float to the surface, leaving substantially liquid wastewater in the middle clear zone of the tank that can be released from the tank to the sewer collection network.
The ClearConvey pipe network transports the liquid wastewater using gravity flow through a series of small bore sewers. Flow is more efficient because the sewage solids have already been removed from the wastewater, allowing for sewer design with fewer constraints. Whereas conventional sewers must achieve a certain flow velocity in each pipe in order to keep solids in suspension, ClearConvey can be designed with nearly flat pipe slopes without concern for sewage blockages. Small bore sewer pipes are optimized for flow conveyance rather than solids carrying capacity.
This is especially important in communities that use less water. For conventional systems, low water usage may not generate enough flow velocity to move sewage solids through the pipe network, resulting in blockages that are difficult and costly to remove from underground sewers. ClearDigest protects the ClearConvey pipe network from blockages, regardless of the sewage volume generated from each building. Clearford One operates continuously with any range of daily water usage, dramatically reducing the cost of operations, and enabling wastewater servicing in communities where conventional whole sewage systems can’t be contemplated.
Harnessing Natural Processes
The design of the Clearford One system relies on naturally occurring processes for sewage treatment. ClearDigest smart digesters are configured to enhance biological treatment by anaerobic bacteria—the same abundant organisms that humans use to digest food in our bodies. These bacteria break down the pollutants in sewage and decompose the biosolids.
The bacteria become more efficient as they mature, so the ClearDigest design provides an optimum retention time and contact volume to maximize decomposition of sewage in the smart digester. A proprietary inlet device uses the kinetic energy of the incoming sewage to gently mix inside the tank to increase contact between the sewage and bacteria to enhance digestion.
The impact of ClearDigest is that 75% of suspended solids and 65% of biochemical oxygen demand (BOD) are removed from raw sewage in the smart digester tanks. This constitutes much of the secondary (biological) treatment that is typically required for wastewater treatment. Therefore, the pollutant loading to the ClearRecover treatment plant is significantly reduced such that the capital and operating costs are also reduced.
Modulating Flow at the Source
ClearDigest smart digesters modulate the wastewater flow quantity and quality being delivered to the ClearConvey and ClearRecover components. This is achieved through ClearDigest design features that passively manage the fluctuation of sewage through the tank.
Daily peak sewage volumes are controlled through a patented outlet device in each smart digester that restricts the outflow from the tank. Clearford One system peak flows are substantially reduced compared to peak inflow volumes, lessening the need to oversize downstream collection and treatment infrastructure by as much as 50% compared to conventional sewage systems. The result is smaller pumps, smaller tankage, and smaller footprint for wastewater infrastructure.
New sewage is continuously mixed with older wastewater in the smart digester tank, creating a consistent pollutant loading that leaves the tank. The normalization of wastewater quality eliminates shock loading to the treatment plant, which allows the final optimized treatment package to target the specific effluent character for efficient treatment.
Optimizing the Infrastructure
By removing solids, reducing peak flow, and eliminating extraneous flows, Clearford One follows a different approach for optimizing wastewater infrastructure using sealed small diameter sewer pipes with fewer and smaller system access points to convey liquid effluent for final treatment.
Conventional sewers use large pipes and manholes to accommodate sewage solids, peak flow, inflow and infiltration. However, these rigid components are increasingly susceptible to leaks through joints and cracks over the life of the system. Inflow of storm runoff and infiltration of groundwater use up the conveyance capacity of the system and add significant pumping and treatment costs for downstream infrastructure. Leaky joints may also allow sewage to pollute valuable soil and groundwater resources.
ClearConvey uses flexible high-density polyethylene (HDPE) pipes with thermally fused joints and watertight system access points that eliminate groundwater infiltration and sewage leakage to the environment. HDPE pipe is the same material relied upon worldwide in the natural gas industry for providing reliable fully sealed pipe networks. Robust HDPE piping has a design life over 90 years. It is resistant to corrosion and biological attack, and is non-reactive in the environment.
Sealed sewers guarantee that only the sewage from the connected buildings is conveyed to the downstream pumping and treatment facilities. Groundwater and seasonal storm influences are eliminated from the design of the Clearford One collection and treatment system.
System Access Points
In conventional sewer systems, bulky manholes are typically required at every pipe intersection and change in pipe direction, slope and sewer size. These manholes are costly to install and become a significant source of inflow and infiltration over the life of the sewer system. Although intended for maintenance access to the underground system, they are often unsafe for workers because of the buildup of harmful gases, confined space entry, and corrosion of manhole components.
The Clearford One system does not require large manholes for maintenance access to the underground system. Instead, system access points (SAPs) are a safe no-entry alternative providing ground level access for inspection and maintenance of the ClearConvey small bore sewer network.
SAPs are vertical cleanout structures spaced throughout the ClearConvey network at regular 80 to 250 metre intervals. They are not required at pipe intersections and changes in direction or pipe size. This is because flexible HDPE piping is used with fused joints and fittings, allowing for smooth curves and pipe transitions throughout the small bore sewer network rather than rigid intersections. Furthermore, only liquid wastewater is conveyed in the system so there is no risk of blockages from sewage solids at these transitions in the pipe network.
SAPs are small diameter sealed cleanouts that are typically fewer, shallower and easier to install than large conventional manhole structures. They are watertight while still allowing for venting from the small bore sewer network to prevent the buildup of gases and hydraulic locks in the system. They are configured to provide ground level access for maintenance, including occasional flushing of the pipe network using a simple water hose and inspection using standard closed-circuit television (CCTV) camera technology.
When wastewater pumping is required, Clearford One may use only a third of the pump stations required in a conventional system. This is because ClearConvey small bore sewers can have half the slope of conventional sewers, resulting in shallower pipes over longer distances. Furthermore, pumping is simplified by the use of smaller pumps that are only required to handle liquid effluent, not messy sewage solids. This reduces energy use, as well as capital and maintenance requirements.
Optimized Treatment Plant
ClearRecover treatment operations are simplified, taking up less space and delivering cost savings. Conventional treatment plants require large surge and settling tanks that take up significant real estate and add operating costs. Since ClearDigest tanks perform so much of the primary (physical) and secondary (biological) treatment, loading to the ClearRecover plant is significantly reduced—resulting in lower capital, operating and maintenance costs. At half the size of conventional treatment plants, ClearRecover can more economically employ the best treatment technology to meet the local clean water requirements, whether it is for reuse or release back to the environment.
Clearford One—A Sustainable Solution
Clearford’s approach to optimizing the design and installation of wastewater infrastructure for long-term sustainability enables responsible development and prosperity for communities. Clearford One is more efficient, longer lasting and less expensive than conventional systems.
The efficiency of Clearford One is driven by clear understanding of hydraulic principles and natural processes for wastewater conveyance and treatment. By harnessing naturally occurring physical and biological processes like gravity and anaerobic digestion, Clearford systems are designed for low maintenance, reliability and minimal power consumption.
The components of Clearford One are selected for their constructability and life-cycle cost. By using high quality and locally available materials and construction methods, Clearford One systems are installed to last underground for over 90 years—almost twice as long as conventional sewer systems. That means maintenance disruptions and renewal costs are significantly less for communities.
Clearford One is less expensive to install than conventional collection and treatment systems because of the advantages created by our unique design approach. By removing solids at the source, modulating peak flow, and eliminating extraneous flows, wastewater infrastructure is smaller, shallower and easier to construct. But the largest savings will come through lower life-cycle operating and maintenance costs.
Benefits of the Clearford One System
1. Easier Installation
ClearConvey small bore sewers are flexible plastic pipes that are easily installed using open trench or trenchless construction methods. ClearDigest tanks are lightweight plastic, brick or concrete that can be rapidly installed at any site. The ClearRecover treatment plant requires fewer treatment operations and less tankage than conventional plants, resulting in quicker installation and commissioning.
2. Flexible Deployment
The Clearford One system allows more flexible deployment to suit communities’ needs. Topography, soil conditions and land use are easily accommodated by the use of flexible pipes for solids-free wastewater conveyance. This makes Clearford One well suited for servicing existing communities that previously developed without the rigid constraints of conventional sewers or septic systems.
3. More Affordable
Clearford One is less expensive to install than conventional sanitary collection and treatment systems. Sanitary sewers can be installed alongside potable water services in the same trench for significant construction cost savings. But the largest savings will come through lower life-cycle operating and maintenance costs.
4. Longer Lasting
ClearDigest and ClearConvey components are installed to last underground for over 90 years—almost twice as long as conventional sewer systems. That means maintenance disruptions and renewal costs are significantly less for communities.
5. Prosperity Enabling
Clean water and sanitation are basic needs that lead towards a healthy and prosperous society. Clearford One is recognized by the World Bank as being uniquely suited to deliver affordable modern wastewater servicing to the water scarce and developing regions of the world.
6. Less Water Usage
Clearford One has no minimum water usage requirement unlike conventional sewers that rely on water flow to convey sewage solids. This is extremely valuable for water scarce regions and communities that are succeeding in water conservation and recovery efforts.
7. More Sustainable
Clearford One follows a unified life-cycle approach towards responsible water management and wastewater servicing for communities. The system enables low water usage, minimal power consumption, and smaller ecological footprint during construction and operation.
Frequently Asked Questions
About Clearford Water Systems
What does Clearford Water Systems do?
Clearford Water Systems is a water management company that provides unified water solutions for all aspects of water and wastewater management, treatment and reuse. Clearford Water Systems is a single-point provider of turnkey water management solutions for new and established communities. Clearford works with your team to deliver water systems for a variety of applications, from residential to industrial servicing. At the core of Clearford’s water management offerings is the proprietary Clearford One wastewater system, which enables the efficient extension of additional sustainable water management solutions. Clearford is well positioned to provide a full suite of water infrastructure services ranging from design and construction to financing and operation.
What is Clearford One?
Clearford One is a complete wastewater solution for the collection, conveyance and treatment of sewage. The system is built on three core products: ClearDigest smart digesters, ClearConvey small bore sewers (SBS), and the ClearRecover optimized treatment package. Each product is fully engineered for efficiency and optimized for total system performance. Sewage is collected in ClearDigest smart digesters for pre-treatment of pollutants before conveyance of solids-free effluent in the ClearConvey SBS gravity pipe network to the ClearRecover treatment plant for final polishing and water recovery. This proven wastewater system provides a variety of benefits compared to other systems, including improved environmental performance, lower capital and operating costs, more flexible deployment, and extended life cycle.
Is my community/project suitable for implementation of Clearford One?
Clearford One is a flexible solution for both small and large scale deployments. It unlocks servicing potential for applications in:
- New developments, including residential and mixed land use;
- Commercial, institutional and light industrial sites;
- Resorts and recreational facilities;
- Retrofits for existing unserviced communities;
- Collection systems connecting to existing sewers with limited capacity;
- Collection systems for decentralised wastewater treatment;
- Areas with challenging topographic, soil/rock and water conditions;
- Rural and remote areas that may lack reliable water and power supply;
- Low water use communities.
Are there minimum and maximum sizes of projects?
There are no limitations on project size for the application of Clearford One wastewater systems. Small projects take advantage of the low cost for operation and maintenance over the 90+ year life cycle of the system. Medium size projects are enabled by the reliable system performance and high quality treatment options. Larger projects can minimize their environmental footprint through the efficiency and optimization of Clearford One components to manage wastewater pollutants and flows from collection to final recovery of treated water.
Operations and Maintenance
Is Clearford One easy to operate?
Clearford One is designed for easy operation over the life cycle of the system. ClearDigest and ClearConvey collection system installations are proven to have virtually no scheduled maintenance requirements. Operation of sanitary pump stations is greatly simplified thanks to solids-free effluent pumping—cleaning and equipment maintenance are reduced compared to messy conventional pump stations. Operation of the ClearRecover treatment plant is also simplified because of minimal solids and sludge handling requirements, as well as reduced peak flows.
Does Clearford One require frequent maintenance and/or repairs?
The Clearford One system requires minimal maintenance because of its robust design and construction. ClearDigest smart digesters have built-in features that perform over a wide range of operating conditions. These passive features do not require any maintenance and contribute to prolonged operation of the tanks, which require pumping only after decades of normal use. Since solids and grease are captured in ClearDigest, only liquid effluent is conveyed in the ClearConvey small bore sewer network with virtually no buildup of solids in the pipes. Sewer flushing requirements are minimal during the life of the sewer. Maintenance and repairs for pump stations are similarly infrequent since equipment is not exposed to damaging sewage solids.
What are the mechanical power requirements for operating the Clearford One system?
Clearford One is a passive wastewater collection system that relies on gravity and the kinetic energy of sewage flow to operate. No external power source is required to operate the ClearDigest and ClearConvey components, unless wastewater pumping is required because of topographical constraints. If pumping is required, the equipment uses less power because fewer and smaller pumps are needed, and these only need to handle liquid effluent and not messy sewage solids.
What is HDPE pipe and why is it used for ClearConvey sewers?
High density polyethylene pipe (HDPE) is a robust plastic material resistant to acid and biological attack while lacking the rigidity that causes other types of plastic pipe to crack. HDPE pipe lasts over 90 years and can be installed in flexible horizontal and vertical alignments to go around obstructions, such as foundations, other utilities or trees. HDPE pipe can be fused together, creating strong and watertight joints that will not leak over the life cycle of the pipe.
How is Clearford One installed?
The three components of Clearford One are efficiently installed using conventional construction techniques. ClearDigest smart digesters are plastic, brick or concrete tanks installed similarly to septic tanks using open excavation. The ClearConvey pipe network can be installed using open cut excavation or trenchless methods. Open cut trenches are typically narrower and shallower for ClearConvey than for conventional sewer construction. Trenchless horizontal directional drilling is enabled by the use of flexible fused HDPE pipe.
Installation of the ClearRecover optimized treatment package depends on the type of treatment technology that is selected to meet the project requirements. For basic treatment options like constructed wetlands and lagoons, there is considerable site work required for installation. Alternatively, compact mechanical treatment plants can be manufactured offsite and assembled with minimal impact at the site.
How deep are ClearConvey small bore sewer pipes?
ClearConvey pipes can be buried as shallow as 30 centimetres and as deep as required for service connections to the Clearford One system. Other considerations that affect the depth of sewers are site topography, soil/rock and groundwater conditions, traffic loading on the pipe, and frost penetration depth in cold climate regions. Since the ClearConvey pipe network conveys only liquid effluent, small bore sewers can be laid with a minimal slope, typically 2 metres deep for every kilometre of horizontal distance. This can reduce the depth of sewers and number of pump stations required for most installations compared to conventional sewer systems.
Does Clearford One limit wastewater treatment options?
Clearford One is compatible with virtually all wastewater treatment technologies including lagoons, constructed wetlands, and mechanical treatment plants. Existing wastewater treatment facilities benefit from the greatly reduced requirements for primary and biological treatment, and planned wastewater treatment facilities can be downsized by as much as 50% resulting in reduced capital and operating costs. The ClearRecover optimized treatment package is tailored to the unique effluent characteristics and flow of the Clearford One system, and to meet the local needs, regulations and conditions for each project.
Can Clearford One co-exist with a conventional sewer system?
Clearford One is compatible with existing conventional sewer and treatment systems. A new development or infill units can be serviced by a ClearDigest and ClearConvey collection system and connected to an existing conventional sewer network and treatment plant. In fact, Clearford One uses up less capacity in the existing system, allowing communities to maximize the remaining capacity in their conventional system.