Compromised Underground Storm Drain Infrastructure (City of Santa Rosa)
Map of Damaged Storm Drain Infrastructure
View map of current underground damaged storm drain infrastructure here: Storm Drain Infrastructure Map (3MB, map updated: 1:21pm 11/30/17)
Burned Storm Drain Pipes Discovered in Fountaingrove
After the wildfires, an immediate assessment of storm drainage infrastructure was launched throughout Sonoma County. During the assessment, the City of Santa Rosa has identified some sections of underground storm drain pipes that were destroyed by the fire in the Fountaingrove area. In these areas the underground storm drain systems were constructed with High Density Polyethylene (HDPE) pipes – a type of plastic. During the wildfires, sections of the plastic pipes caught fire and were destroyed. The locations vary and in some instances up to a few hundred feet of the storm drain infrastructure was destroyed or melted. This has resulted in underground voids and cavities that could cause sink holes, debris, mud flows and/or flash flooding concerns. With rain in the forecast, the risk of these events is elevated and the City of Santa Rosa and County of Sonoma are encouraging residents to stay alert for landslides, sinkholes, and other rain-related issues, particularly in the fire impact areas. If you see evidence of flooding, mud and debris flows, or sinkholes in your area, call 911.
Are There Other Burn Areas in the City that Should be of Concern like Coffey Park?
The reason the HDPE pipe has been observed primarily in Fountaingrove is because it wasn’t used until about 20 years ago, and Fountaingrove is a newer development. The Coffey Park area is older and even if there was an HDPE pipe there, the risk is much less because Coffey Park is flat and the pipes are much shallower. In Fountaingrove, there’s more risk if we have a collapse because the pipes are deeper and there’s more hillside exposure.
City Assessment and Mitigation
There are several specialized crews currently working to make a thorough assessment for any compromised storm drain infrastructure in areas affected by the fires using closed circuit TV cameras to inspect the pipes. The assessment is being expedited in anticipation of the rainy season. If the assessment process identifies any areas of enhanced concern, residents will be notified immediately.
Additionally, teams of engineers and geotechnical experts are also in the field performing risk assessments for potential flood or mudslide areas that may result from the damaged pipes. The City is also making plans for emergency mitigation measures and repairs to destroyed storm drains. During the next several days, crews will be in the field monitoring the known destroyed infrastructure areas, and emergency personnel are standing by in the event that conditions change and residents need to be evacuated.
What Residents Can Do to Be Prepared
Residents, especially in the Fountaingrove area, should exercise extra vigilance and have a plan to leave in the event it becomes necessary.
If you see evidence of flooding, mud and debris flows, buckling of roads, or sinkholes in your area, call 911, and avoid the area.
Stormdrain System Assessment: What is it?
Press Conference: Heightened Risks Related to Incoming Rain
Click here for a full text summary of the press conference.