Inflow and Infiltration
Ever heard of inflow and infiltration? Here’s a hint: there was a lot of it this past Tuesday.
Infiltration is groundwater that enters the sanitary sewer system through cracks or leaks in sewer pipes or manhole covers. Inflow, on the other hand, is stormwater that enters sanitary sewers via an illicit connection like a roof drain or down spout. Either way, as today’s Post and Courier article “Tidal Water Bacteria Levels Monitored After Two Sewage Spills” makes clear, it’s a serious issue for sanitary sewer systems and our right to clean water.
Inflow and infiltration are one cause of sanitary sewer overflows. Other causes include blockages, power outages, and sewer line breaks. Since we started tracking these events in December 2011 there’s been 23 of them. The smallest are a few hundred gallons while the largest was around 500,000 gallons. There were three overflows this past Tuesday.
Preventing sanitary sewer overflows is a tough job. The average sanitary sewer system in our area has several hundred miles of gravity sewers, force main, and service laterals, hundreds of pump stations, and a sewage treatment plant or two. All that infrastructure and equipment has to operate flawlessly 24/7, rain, shine, occasional snow, or hurricane. Prevention requires nearly constant inspection, maintenance, and upgrades. And, of course, lots of money.
The next time pay your bill to Charleston Water System, Mount Pleasant Waterworks, or the North Charleston Sewer District, remember you’re helping prevent sanitary sewer overflows. You can also encourage your sanitary sewer system provider to invest more resources in inflow and infiltration prevention. If you see an overflow immediately report it to you sanitary sewer service provider. Clean water is priceless, but it costs money. And it’s worth paying for.
