Tag Archives: combined system

When a tearful child drops a goldfish into the toilet bowl she imagines a burial at sea and final peace. There is no talk of sewage or waste treatment. She flushes the toilet without a clue about what really happens to her fish. The adults at the funeral have a different vision. They assume sewer pipes carry the goldfish to a treatment plant on the American or Sacramento rivers where modern technology churns out clean water. For the most part, they’re right. The majority of neighborhoods in American cities successfully funnel domestic sewage, to treatment plants using sanitary systems that seem to satisfy public health and anti-pollution advocates. But whether or not the system is sanitary depends on the age of the sewage infrastructure. In Sacramento the news is bad. We’ve got some old, funky pipes.

In newer split sewer systems, the goldfish glides down the household plumbing pipes to a dedicated sewer line that connects to the water treatment plant. At the plant the waste is cleaned out and the water is ready to be processed into potable water. The plant discharges any excess, sewage-free water, into the river. The key to this design is the separate, dedicated pipe that takes sewage to treatment plants. The storm drains connect to a separate pipe that carries rainwater and runoff to the river. Unfortunately, our East Sacramento and other older neighborhoods, sprinkled throughout the city rely on an older, combined system. This is where it gets messy.

Picture a sunny, dry August day. All of the house waste and gutter water flows into one pipe. (There is no dedicated sewage pipe.) Underground the pipe splits. One pipe burrows further underground. This lower pipe travels to the treatment plant. Gravity pushes waste and runoff into the lower pipe and on to the plant. The upper pipe heads to the river, but it has a partial dam that stops the waste and runoff, forcing it back into the lower pipe. This dam works really well in good weather. This is called a combined system and on sunny days the goldfish takes the fork to the treatment plant.

Now it’s a rainy March, roaringly rainy. Pounding rainwater spews off homes and twirls away down storm drains. All of this water, along with the waste, heads to the fork in the system. The harder and longer it rains more and more water enters into the pipes until the lower pipe that connects to the treatment plant is overwhelmed. This is when the second, upper pipe comes into play. All the water that the lower pipe can’t handle backs up into the upper pipe. The waste water heads straight to the partial dam inside the pipe, pushing and rising until it overspills the top. Raw sewage, roof runoff, car oil and the goldfish get dumped into the river. And on super stormy days the waste also pushes up the storm drains flooding the streets with sewage. The child’s fish is now in the gutter.

If you can imagine the spaghetti snarl of sewer pipes under our city, you know that it will take billions of dollars to update our combined sewers to split systems. One cheaper solution for East Sacramento, put forward by the city, is to excavate a forty-foot-deep, more than an acre in size, water holding chamber in McKinley Park. The project will take about two years and it does offer a solution to the flooding in East Sacramento. The vault would hold the overflow runoff and sewage on rainy days, so the streets don’t flood. And the goldfish would be in the buried box, waiting it’s turn to move on to the treatment plant.

But here’s the thing. Historic McKinley park is most used neighborhood park in Sacramento. Thousands and thousands of people from throughout the city recreate, marry, eat, play and relax on its green lawns. The building of the vault is a huge disruption and not really necessary. It’s a patch.