When clearwater gets into a sewer system it causes an increase in the amount of wastewater in the sewer system. This is bad because wastewater costs money to transport and treat. This results in higher sewer bills. There are also health risks. An increased amount of wastewater can cause sewer backups and overflows. When this happens we end up with sewage on our streets, lawns, and other public places.
Infiltration refers to groundwater that finds its way into sewers via broken or cracked pipes, broken side sewers, root intrusion, faulty lateral connections, and deteriorated manholes.
As the term implies, infiltration is about groundwater slowly seeping into the sewer system. The amount of infiltration will usually vary according to season. For example, infiltration will be higher during rainy or snowy seasons because of the increased amount of groundwater.
Inflow refers to surface stormwater that rapidly flows into a sewer system from above-ground sources like faulty manhole covers, foundation drains, uncapped cleanouts, storm drain cross-connections, and downspouts. Inflow will naturally be greater after heavy rainfall or snowmelt. Exfiltration is defined as the leakage of wastewater out of a sanitary sewer system.
Exfiltration seeps out of broken or damaged pipes and manholes. Wastewater that leaks from defective pipe joints and cracks may contaminate ground and surface water and nearby water bodies. It can also cause pipe structure failures due to erosion of soil support, and ground subsidence due to erosion of underground soil.
The EPA considers infiltration excessive if a system's average dry weather flow is more than gallons per capita per day. This total includes infiltration, domestic flow, and nominal industrial and commercial flows. It does not consider regional and seasonal factors like the intensity of precipitation events and varying groundwater levels. For this reason, some states prefer a criterion of gallons per day.
Whatever the calculation, most operators agree that if a plant experiences overflows during storm events, the inflow is excessive. Your region may rely on entirely different standards, so staying up to date on the most recent regulations is the only way to avoid fines or government interventions. What is excessive inflow and infiltration? Flow monitoring is the practice of measuring wastewater flow in the system over time and comparing it with a baseline flow estimate.
Flow monitoring can be used to identify and prioritize areas for further inspection. The method produces two data points: the amount of electrical leakage a proxy for water leakage and the distance within the pipe of the leakage. Learn more about this method's reliability in this white paper.
Making smart decisions about sewer maintenance requires both a quantitative approach such as FELL and flow monitoring and a qualitative approach visual inspection methods to infiltration.
They can also use their findings to create a plan to combat inflow and infiltration. A comprehensive approach to locating defects involves inspecting all aspects of a collection system, including manholes, sewer mains and laterals.
Manholes generate a disproportionate amount of inflow and infiltration. Field inspectors should evaluate the manhole lid, frame condition and the frame connection for any structural defects or leak sources. The interior of a manhole can be assessed with a manhole inspection camera or a zoom survey camera also called a pole camera.
Manhole inspection cameras capture both visual and dimensional data points, such as a flat scan with detailed images of the manhole wall and point cloud data for 3D visualization. A zoom camera uses a video camera mounted on a sliding pole. Groundwater seeps into sewer pipes through cracks, leaky pipe joints and deteriorated pipes. Sewer inspection crawlers use a video camera mounted on a remote-controlled robotic crawler that is connected to a monitor. An operator watching the video can stop to study parts of the pipe to find the specific location and cause of infiltration.
Laterals can be accessed from either end: from inside a home using a push camera or from the main line. Lateral launch crawlers are designed to travel down main lines and then launch a secondary camera into laterals. In these cases, further investigation work may be needed to identify additional defects.
During CCTV, camera operators find defects and rate a sewer line's structural integrity. The result is a higher risk of overloading the pipe network leading to potential basement flooding, and increased flows and volumes that must be treated at the plant. The sanitary sewer system is an underground pipe network that collects wastewater produced by houses, businesses, and institutions.
The purpose of the pipe network is to direct the wastewater to a treatment plant where the water is treated before being discharged into Lake Ontario. The storm sewer system is an underground pipe network that collects rainwater runoff. During storm events, rainwater infiltrates into pervious areas, such as grassed lawns and gardens.
Any rainwater that does not infiltrate will turn into runoff that will flow down impervious areas, such as roads and parking lots. Catch basins and other inlets are designed to collect the rainwater runoff and convey the water through a storm sewer system. To measure wastewater flows through the foul sewer system it is important to select the appropriate flow meter, such as the Detectronic MSFM ultrasonic wastewater flow monitor.
The MSFM is a multichannel unit that records flow, level and depth data. Used in conjunction with a rainguage , data is transmitted to Detectronic data analysts, who can then make comparisons between the measured inflow and infiltration and the corresponding rainfall intensity. This analysis will reveal the extent of inflow and infiltration.
Once a source of inflow and infiltration has been discovered appropriate action to resolve the problem can be taken, including fixing or replacing damaged or leaky sewer pipes and notifying property owners of improper connections. We are specialists in the design, manufacture and installation of ultrasonic wastewater flow and level monitoring equipment for the water industry. At Detectronic, we provide a range of wastewater management services to help you.
0コメント