Whether or not they are required to obtain permits or submit documents, public agencies are subject to the substantive requirements of this subtitle, unless adjustments or exceptions are granted as set forth in Section 22.800.040 (Exemptions, Adjustments, and Exceptions) or the requirements have been waived under subsection 22.807.020.A.3.
(Ord. 123105, § 2, 2009.)
Excerpt from Seattle Drainage Systems
Seattle has three types of systems to move, or convey, stormwater and wastewater: a combined sewer system, a separated sewer system, and a partially separated system. While there are some areas of overlap, different parts of the city have different types of systems. During heavy wet weather conditions, the combined sewer system can be overwhelmed with stormwater. When the system is overwhelmed, the untreated mixture of sewage and stormwater overflows at designated relief points called outfalls; these events are known as combined sewer overflows (CSO). While this helps to keep combined sewage from overflowing in streets or backing up into homes and businesses, it contributes pollution to Seattle’s waterbodies.
In a combined sewer system, wastewater and stormwater travel in the same pipes to treatment plants. 33% of Seattle's wastewater system is combined.
In a partially separated sewer system, wastewater from inside homes and businesses, and stormwater from roof gutters and downspouts are conveyed in the same pipes to treatment plants, while stormwater from streets is conveyed through a separate drainage systems to drainage outlets. 40% of Seattle's wastewater system is partially separated.
In a separated sewer system, wastewater and stormwater travel in separate pipes. Wastewater is conveyed from homes and businesses to treatment plants. Stormwater is conveyed through a separate drainage system to drainage outlets. 27% of Seattle's wastewater system is partially separated.