by Mayor Dale Ross
Each time we use a sink or flush a toilet and the water goes down the drain, we probably don’t give much thought to where it goes and how it gets there. Since most of the wastewater collection and treatment system is literally underground, many of us may not know much about it.
Our wastewater system is the Rodney Dangerfield of infrastructure. It doesn’t get much respect, or attention. Until recently.
The extension of a wastewater line to serve a new residential development on Airport Road has sparked discussion of sewer lines. The proposed Homestead residential development would connect to a segment of the Berry Creek Interceptor. This is a large wastewater line that has been in the City’s wastewater master plan since 1989.
It is important to understand that the Berry Creek Interceptor is a long-term City project, not an idea created by developers. Portions of the Berry Creek Interceptor or wastewater line were built before the first homes in Sun City were constructed in the early 1990s. The Berry Creek Interceptor has been a phased project with new segments constructed as development occurs along the Berry Creek watershed so new development shares the costs for pricey infrastructure projects.
The alignment of the interceptor, which follows Berry Creek from Sun City to the Pecan Branch Wastewater Treatment Plant on the east side of Georgetown, includes a segment along Berry Springs Park. The City is working with Williamson County to find a route for the interceptor. The placement of the line will be sensitive to the park setting and ensure that the natural assets of the park are protected.
While a wastewater line going through or adjacent to a park was a surprise to some, a broader look at our wastewater collection system shows that we already have interceptors along every river and tributary in Georgetown. A number of these interceptors run in or near parks, including San Gabriel Park.
The map shows the major wastewater lines that are 18 inches in diameter or larger in our collection system. Smaller lines serving individual streets and neighborhoods are not shown.
This map illustrates that the city’s major wastewater lines are located along creeks and rivers in all sectors of the city. This is because the wastewater system works through a series of pipes that allow gravity to do the work. For this reason, wastewater lines mirror the above-ground drainage ways that we call our watersheds.
The alternative to a wastewater system that follows the contours of natural topography requires sending water uphill and going against gravity. Because we do not have large interceptors in all of our rivers and streams, the current wastewater system must work against gravity in some places.
These areas are served by lift stations and force mains. A lift station is a collection basin with electric pumps that pushes wastewater over elevations in the terrain through a pressurized pipe known as a force main.
One major problem with force mains and lift stations is that they depend on electricity and mechanical pumps. A range of issues can lead to power outages and pump failures. When this happens, lift stations can overflow and spill wastewater. Most stations have redundant pumps and power, but lift stations are still susceptible to mechanical, electrical, and equipment failures. When wastewater spills occur, they flow into the rivers and streams that the system is designed to protect.
Additionally, odor can be a major concern with lift stations. The constant movement of wastewater through a gravity system actually helps reduce odor significantly.
Due to the disadvantages of lift stations and force mains, the wastewater master plan would eliminate as many as possible and replace them with gravity mains.
Most of the city’s wastewater collection system is over the Edwards Aquifer Recharge Zone. As such, each gravity line is visually inspected at least once every five years to ensure they are in good working order.
The City’s wastewater system, mostly unseen to residents, follows a master plan to reduce environmental impacts with gravity lines. This plan ensures the safest operation of an under-appreciated element of our public infrastructure.