Q&A Storm Water Discharge Systemback
"Coronado is committed to water quality" - City Manager Blair King
Q&A Storm Water Discharge System
The City of Coronado is committed to water quality. We want the public to know what we do to keep our bay and ocean clean and to comply with regional, state and federal water quality mandates. To increase awareness of storm water management and surface water quality, the City of Coronado has put together this Q&A.
Q. Why does the City of Coronado have separate sanitary sewer and storm drain systems?
A. Sanitary sewer systems and storm drain systems are distinct and must be kept separate. Everything that goes into the sanitary sewer system - from toilets, sinks, laundry water - is sent to the Point Loma Wastewater Treatment Plant to be treated and discharged into the local receiving waters. The storm drain system helps prevent flooding by transporting water away from developed areas. The City's storm drains typically carry untreated rain water from the City's streets and release it into the bay or ocean.
Q. Why is rain water released untreated?
A. Sewage is expensive to treat. Rain water is much cleaner than sewage. To help prevent sewage treatment plants that treat millions of gallons of raw sewage daily from being overwhelmed during rain events and spilling contaminated sewage into the environment, most storm water in cities around San Diego County, including Coronado, either freely flows or is piped directly to the local receiving waters.
Q. Why can't storm drain water be sent to Point Loma to be treated?
A. In addition to overwhelming the Point Loma treatment plant, the City's infrastructure could not handle storm water runoff. The City of Coronado's sewer system was designed and built to transport sewage and does not have the capacity to handle more without risking system failure. Furthermore, the cost of treating the City's sewage is a huge consideration. Last year, Coronado residents paid $2.1 million in treatment costs. Any increases to the system must be shared by users, Coronado residents.
Q. What does the City do to limit pollutants in storm water runoff?
A. Storm water from rain events is itself very clean. However, once it hits the ground, it begins to collect the contaminants and pollutants it encounters on its journey to the bay or ocean. Coronado has a very robust program to capture these pollutants before they reach the receiving waters. The City uses "best management practices," guidelines created to reduce pollutants from reaching receiving waters, including frequent street sweeping, diverting dry-weather flows to the sewer system, use of perimeter runoff controls at construction sites, and other approved techniques.
Q. What else does the City do to keep our ocean and bay clean year-round?
A. Coronado has 13 dry-weather diverters on many of the storm drain outlets as an extra protection to its receiving waters. The diverters capture all summertime or dry-season runoff - from home car washing, over-irrigating lawns, illegally discharged water - and sends it to the sanitary sewer system to be treated so that no runoff besides rain enters the bay or ocean. Additionally, during storm events, the "first flush" of rainwater rushing through the storm drain system, usually the most heavily polluted, also goes to the sanitary system. These systems are continually inspected and cleaned to ensure proper working order.
Q. Why is there a flooding issue in the Country Club Estates area? What makes it different?
This map from 1886 shows the streets and plots mapped out for building before the Hotel del Coronado was constructed. On the left, the Spanish Bight waterway is noted and was located where the Country Club Estates now sits. It was filled in sometime in the early 1940s to create more room for the military.
Q. What has the City done to deal with the minor flooding in Country Club Estates?
Q. Besides the City, who monitors the storm drain system?
Q. What safeguards do our sewer and storm water systems have to prevent failures?
Q. What can residents do to help keep our waterways clean?
Q&A Storm Water Discharge System October 23, 2012