Engineers

Engineers

The Small Bore Sewer™ (SBS™ ) system is appropriate for new development and re-servicing older communities. The system comprises of a piping network for transmission of sewage fluids and on-site digester tanks attached to the homes/buildings that provide for an early separation of sewage solids and the liquid portion of sewage. The piping system is a one-piece network of conduits that collect the sewage liquids and directs the effluent to a suitable receiver. The piping is comprised of thermally fused high density polyethylene (HDPE) that conveys the system fluids from the outlet of the digester tanks to the receiving infrastructure. The receiver is typically a sewage pumping station or a sewage treatment plant. The on-site individual clarifiers act to separate the solids and liquids, and in doing so, removes the occurrence of solids blockages in the collection piping and appurtenances, as well as reducing the sludge volume to be processed at the treatment and disposal facilities.

Functionality

The SBS™ collection system is a high performance technology that simplifies the process of sewage transmission. The upstream separation of solids and liquids results in a simplified design, maintenance schedule, and system operation. The digester separates solids from the sewage and retains the solids. The piping is smaller than historic systems and is designed for actual cumulative flows, and not related to over-sizing due to extraneous flows and infrequent peak flows. The piping collects and conveys the liquids for further treatment. The solids reside in the digesters for an extended period of time (can be greater than 30 years depending on the number of users and connections), allowing natural digestion of the sewage sludge and effectively eliminating solids handling as a function of sanitary sewers. There is no scheduled maintenance of the pipe network for the life of the system. The only elements of routine maintenance are the effluent pump stations which are installed on an as-required basis to deal with gradient requirements. SBS™ is a modern technology that avoids the age old process of moving flushing sewage solids from homes and businesses to ultimate treatment and discharge.

System Venting

System venting is tied to two separate solutions. The tanks require venting for the removal of system doors and to provide in the movement of sewage from the home to the tank. Secondly, the mains require venting in order to allow displacement of air or fluids in the pipe network system. Strategically designed venting is introduced to the main system at key points in order to avoid hydraulic lock as the flows enter and move through the system. Earth vents are also provided to avoid odour. d.

The residence or building stack that is constructed under current codes may be sufficient to provide for the tank venting. A design analysis is provided to place the venting apparatus of the piping in suitable locations to allow for the transmission of the liquids to the receiving infrastructure, and additional filters can be added to the venting apparatus to address any odour control that may be require

Distributed Digester – Function and Quality

Clearford's Distributed Digester is a decentralized primary wastewater treatment and methane capture and conversion facility. The Digester produces bio-gas as a result of the conversion of bio-solids to biogas (methane). The design of the digester has been optimized for hydraulic mixing to achieve maximum conversion, and uses non-mechanical, passive processes to collect and convey the methane to the collection hub or methane conversion facility.

The Digester separates solids from liquids, and contains and directs a predominantly solids-free liquid effluent by gravity through small diameter pipes to the treatment plant. The quality of the effluent is reflected in significantly reduced contaminant concentrations – with total suspended solids reduced by 80%, biological oxygen demand by 29%, total Kjeldahl nitrogen by 25% and total phosphorus by 14%.

The Digester has unique attributes that promote anaerobic digestion and methane generation including passive hydraulic mixing, passive heat retention, and higher interaction between new substrate and old anaerobes. All of this means that solids are effectively eliminated at source.

The tanks act as flow surge suppressors and function to lower system peaking factors. This allows for the use of much smaller laterals and collection mains, pumping stations, and transmission systems. The tanks are sealed to prevent the introduction of groundwater into the collection system.

Once constructed and at design strength, the tanks are subjected to a comprehensive vacuum test in order to verify strength and water tightness. Additional wall thickness and higher strength material is used to provide a more competent vessel when compared to standard tank designs. Hatches are included to allow access to the first and second chamber, and permit the inspection of the connection plumbing between the two compartments. An extended access maintenance hole is designed to be installed over the access hatch that is provided for the sludge chamber. The access is extended by adjustable rings and a PVC surface hatch to the surface of the ground. This becomes the maintenance hole access that is used for sludge removal on the design cycle for the system.

Installation

The SBS™ installation methodology is superior in three aspects: less time, less disruption, and no road closures. Past comparable projects indicated that construction time was cut in half by the use of trenchless technology. Daily installation rates for sewer pipes can be up to 4 times higher with trenching than compared to horizontal boring. Our experience has been that historic sewer systems require many road-closures and community inconvenience, whereas horizontal drilling is efficient, is contained to a much smaller area, requires much smaller equipment and less manpower, and generates little disruption to the community.

Learn more about the SBS™ system