One of the most important steps to maintain the integrity of underground pipes is through proactive and regular maintenance. Unfortunately, since sewer and water pipes are out of sight and out of mind, this sometimes gets overlooked until failures occur. Through regular inspection, however, maintenance schedules for cleaning and removal of roots and grease can greatly maximize efficiencies and work to avoid unexpected repair costs or significant damage. Maintaining a properly functioning wastewater system is no different than regular maintenance on a car – it extends the useful life of the buried asset, minimizes disruption to communities, and prevents costly, reactive, emergency situations from occurring.
Bypass pumping is a key element in the successful installation of most pipeline rehabilitation technologies. The existing sewage flow is temporarily re-routed until the project is completed. A variety of pump types and system configurations can accommodate most any flow volume and configuration. With most small diameter pipelines, particularly on short sections of sewer, plugging should be adequate but must be monitored on a regular basis to prevent backup of sewage into adjacent homes.
It is important to design the bypass system to accommodate the specific flow conditions encountered. The pump system suction lift capability must be matched to the depth of the sewer, which must be matched to the size and length of the discharge piping system. Also, emergency or stand-by capacity should be designed into the system in the event of a pump failure during operation of the system. Many cities require 50% additional capacity in the event of a pump failure and in critical areas 100% has been required.
In commercial and industrial applications, it may be necessary to bypass flow from each individual service connection, since flow interruption may not be an option. Individual cleanouts or sewage pick-up points are identified, and a small pump is set-up directing the flow to the mainline pumps.
Bypass Pumping is a critical element in the successful installation of most trenchless pipeline rehabilitation technologies. Typically, bypass pumping will occur due to new construction, lift station rehabilitation, lift station malfunctioning, broken gravity line, force main rupture, tie-ins, pipeline rehabilitation or a combination of factors.
How it works:
- The existing sewage flow is bypassed, or temporarily re-routed, until the project is completed
- A variety of pump types and system configurations can accommodate almost any flow volume and configuration
- Proper pump and equipment selection can be accomplished by knowing data like peak flow, sewer line size, pipe depth from the surface, duration of the work, potential access issues and any other associated factors
- Pumps are installed upstream of the work area, and a temporary pipeline is installed from the upstream pumps to downstream of the work area where it discharges back into the existing sewer line
The cleaning of a pipeline is performed for a number of reasons including pipe blockages due to roots, grease and sand buildup. Pipes are cleaned to increase available capacity taken up by debris and other materials, as well as to prepare a pipe for the installation of a renewal technology. Most renewal technologies require that the host pipe be totally free of any debris and accumulation before the new product is installed. Cleaning devices will vary depending on the type and amount of debris in the pipe. Most equipment uses a combination of mechanical equipment and water pressure. NASSCO has published a Jetter Code of Practice (available in English and Spanish) which reviews different devices and nozzles that are typically used to clean pipes using high-pressure water.
- Allow for a more complete CCTV inspection
- Restore hydraulic capacity
- Prepare for pipe rehabilitation
Root and Grease Control
Root and grease control are the foundation of any good sewer maintenance program. The EPA states, “Sewer line root intrusion is the single most destructive element facing those responsible for maintaining the wastewater collection system.” Controlling the infiltration of roots into the pipeline preserves the integrity of the joints and keeps the pipeline open and flowing. If roots are allowed to grow into the sewer, sanitary sewer overflows (SSOs) will continue to occur. Routine maintenance of the system for root intrusion by deploying a chemical treatment program has proven far superior to the “historical method of cutting roots out mechanically”, which can damage pipes and lead to thicker re-growth, requiring more cutting. Cutting off the appendages of these intruders is just like pruning a tree top; they very quickly grow back. A properly administered chemical root control program, however, allows for the effective eradication of the roots in a zone that extends to approximately 12″ outside the pipeline. Initially developed in conjunction with UC Davis and the University of Sacramento, chemical root control today has become one of the most beneficial methods used to combat SSOs and pipeline deterioration.
Root Control is a proactive way to control root intrusion into a sewer, preserving the integrity of the pipe and maintaining the hydraulic capacity of the pipeline. Root removal needs to be a part of any pipeline maintenance program.
How it works:
- One method is to cut out roots periodically with a water jetting/mechanical cutting operation
- A chemical root treatment is another method that can be applied directly to the pipe interior to kill the roots in the pipeline and inhibit new root growth for a significant period of time