One of the biggest nuisance problems associated with sewer plants is odor. The small group of Woodacre community members who are supporting the construction of a sewer plant in the Valley are quick to say that this sewer plant won’t smell. The truth is that they have no idea if it will smell or not. They don’t know how often it will smell or the intensity of the odor. The reason they say that it won’t smell is because if they said anything else, you would probably oppose the construction of a sewer plant. But here’s the truth.
- The Wastewater Recycling Study report that issued by Questa Engineering detailing all aspects of this project (available on the Marin County website) includes a section titled “environmental impacts.” In this section the engineers list a series of environmental impacts that the sewer plant will have on our Valley. These include visual impacts, noise impacts, sewer spills, and yes, odor.
- The sewer plant’s filtration system will include something called a membrane bioreactor (MBR). Without getting too scientific, this is part of the filtration system where raw sewage is processed. The engineering report states that the MBR will be partially vented into the atmosphere.
- Sludge is a big odor contributor. Sludge is the solid human waste that gets filtered out of the raw sewage that comes into the system. Sludge will be dewatered, dried, bagged and stored onsite and remain onsite for extended periods. Sludge will only be removed for disposal on a once monthly basis.
- New storage ponds on the San Geronimo Valley Golf Course are key to the sewer plant project. It’s the place where reclaimed water will be stored and then sprayed on the golf course. The engineering report notes that these ponds will have to be monitored for odor. One reason for that is due to the fact that while the sewer plant will filter most human waste out of the sewage, it will not filter all of it and approximately 195 pounds of human waste will enter the holding pond each month.
- The engineering report also notes that the golf course itself, where the reclaimed water will be sprayed, will also be monitored.
- The engineering report also states that odor control is needed and that carbon filters may be used where practicable and if necessary. That language: “may be used,” “where practicable” and “if necessary” should be a concern for you. If you live several miles away, say in the Woodacre Flats, carbon filters may not be necessary at all, especially if you’re paying the bill for those. But what if you live on the corner of San Geronimo Valley Drive and Meadow Way?
- The sewer plant will include an odor control unit that will drive certain gasses through a bed of carbon. This is both good and bad. Good because it will seek to minimize overall odor. Bad because the unit itself is proof that odor is an issue with this sewer plant (as it is will all sewer plants). Also remember, not all odor causing gasses will be moved through the carbon filter. Sludge will dry in the open air and the MBR unit will be vented to the atmosphere.
Overall, no one knows how bad the odor issue will be until the sewer plant is built. But by then it will be too late. That’s risky and dangerous. If you live in the immediate vicinity of the sewer plant, your home values, your ability to enjoy your property and your quality of life could be irreparably harmed. As good neighbors in a small community we do have to ask ourselves how our actions will impact those around us.