The wastewater collection system is designed to eliminate and carry the wastewater through the City’s sewer lines. A vast system of underground sewers, force mains and pumping (lift) stations collect the wastewater from the homes of the city's residents and deliver it to main sewer lines then to the wastewater plants for treatment. The operation and maintenance of over 180 miles of sewer pipe and 18 lift stations are performed by employees of the Wastewater Department. Their responsibilities include maintaining all the lift stations and managing the City’s preventive maintenance program for all items related to the sewer collection system.
Wastewater discharged from a home or business enters the sewer system through service lines 6 inches or larger. These service lines carry the flow of wastewater to the City’s trunk lines consisting of pipes 8 inches or larger. Based on the topography of the city, if the flow is not by gravity, there are lift stations to pump the wastewater from the trunk sewers into the main outfall lines. The wastewater flows by gravity through these large outfall lines, which are up to 24 inches in diameter, to the treatment plants.
Sewer Lift Stations
Lift stations are an integral part of the collection and conveyance system. Collection systems are built to utilize the natural flow of gravity when possible. When wastewater cannot travel through the lines by gravity, pumps are used to force the wastewater through the force mains until it can again be transported by gravity flow. The City of Del Rio has 18 lift stations strategically located based on the topography of the area.
Sewer Line Maintenance
The Water/Wastewater Department keeps the wastewater system functioning properly to accomplish the City’s goal to protect the environment. Despite proactive efforts to maintain the system, operational complications may sometimes occur. Some of the common causes of system problems include using the drain to (1) dispose of items such as grease, paper, garbage or household hazardous waste (2) vandalizing the system by putting foreign or incompatible materials in the system or down manholes and (3) blocking of the system by tree or shrub roots seeking water and entering the collection system.
In order to maintain the wastewater system and to keep it functioning properly the Water/Wastewater Department utilizes the following preventative maintenance procedures:
Visual Inspection: Maintenance crews regularly check manholes, frames and covers to look out for cracks, breaks or missing parts, which may prevent them from maintaining airtight integrity. Replacement and maintenance is scheduled as necessary.
TV Inspection of Lines: As a preventive maintenance tool, TV inspections are performed on sewers lines as a result of line blockages and other sewer related problems. The TV inspection process is critical in the detection and location of needed repairs. With the TV camera, that is lowered into a manhole and pulled through the line, the crew can find the exact location of a lateral connection and type of problem. Testing and repair equipment used in conjunction with the camera will determine if there are areas of weakness in the joints and pipes and look for leakage. This information is valuable in the digging and repair process as it eliminates "guess work" in isolating a problem.
Jet/Vacuum Cleaning: Sewer lines are often cleaned to remove roots or other material then cleaned with high-pressure water by using a combination jet vacuum system. The city has 3 Vactor Trucks to assist our maintenance staff in restoring pipe line and manhole stoppages and conducting regular preventative maintenance. This equipment is used to jet clean the line with high pressure water hose. The debris is then vacuumed from the manhole with the high powered vacuum hose.
Chemical Root Treatment: In some areas, workers may find it helpful to use a foaming chemical root treatment. This foam is pumped into selected sewer mains to kill existing roots and to inhibit their re-growth.
Inflow and Infiltration
An aging sewer system is in constant need of inspection and repair. Cracked and broken sewer lines and manholes allow ground water to enter the sewer system. In additional to groundwater, illegal sump pump connections and roof downspouts add rainwater to the sewer system. This additional water volume is called inflow and infiltration. During a rain event this additional water can overburden the sewer system and cause overflows. These types of connections are reported to code enforcement for action.
All properties built in Del Rio after 2002 have been built with a sewer clean-out, which is a pipe placed into a sewer line to provide an opening at ground level to connect the private property’s service line with the City’s sewer line. Clean-outs are typically installed at the edge of the easement or property line, or in close proximity of the house foundation. The property owner is responsible for maintaining the service line (private sewer) from the property line, including the clean-out, to the home. The City is responsible for maintaining the sewer line from the property line to the main sewer line. This type of pipe allows for easy access to the City of Del Rio’s main line and access to the property owner’s line for the private service connection. It is standard practice to install clean-outs at the edge of easements or property lines. This prevents the necessity of going into private homes to correct stoppages.