Exfiltration is a huge problem facing wastewater infrastructure and water. Caused when wastewater leaks out of sanitary sewer systems through damaged pipes or manholes, exfiltration causes contamination of surface and ground water, plus pipe structure failure due to soil support erosion.
Untreated sewage from exfiltration frequently contains high levels of pollutants, including grease and oil, oxygen-demanding organic compounds, floatables, pathogenic microorganisms, toxic pollutants and suspended solids. Although sanitary sewer systems are engineered to collect and transport wastewater to facilities that treat it before it comes back into the environment, exfiltration can put a serious wrench in these operations by releasing wastewater without proper treatment.
The effects of exfiltration are great. In Albuquerque, New Mexico, city investigators determined that 11% of their collection system’s wastewater was lost due to exfiltration. A British study confirmed that as much as 25% of wastewater can exit a system due to exfiltration, and German researchers have concluded that the country must spend approximately $100 billion to fix their own deteriorated sewer infrastructure in an effort to fight exfiltration.
How can sewer cameras and sewer camera inspection equipment be used to prevent exfiltration?
The first step to detecting and measuring exfiltration problems is to conduct smoke testing, flow monitoring and dye testing. Next, a push camera inspection system, sewer cameras and sewer inspection equipment can be used to prioritize rehabilitation and understand the severity of the issues.
We recommend a comprehensive approach to identifying defects — one that involves thoroughly inspecting every aspect of a collection system, including laterals, sewer mains and manholes. We also recommend inspecting laterals while the sewer main itself is being inspected because they are the shallowest parts of sewer systems and usually have the poorest construction. You can use a lateral launch system to inspect both at once. We recommend pole cameras and manhole scanning cameras for inspection of leaking manholes.
Many different rehabilitation techniques may be used to correct the sources of exfiltration. They include point repair, chemical grouting, fold and form pipes, cured-in-place pipes, sliplining and cement grouting.