Storm Drainage and Special Waste Systems
Storm Drainage
Storm drainage removes rainwater from roofs, courts, and paved areas. Know roof drains, leaders (downspouts), area drains, and storm building drains. Sizing depends on rainfall intensity, roof area, and slope. Understand primary and secondary roof drainage, overflow scuppers, and the dangers of ponding. Learn that storm and sanitary systems must be separate unless combined by the AHJ.
Special Waste
Special waste includes grease, oil, sand, acids, and other harmful discharges. Grease interceptors and oil separators protect the drainage system. Acid waste needs corrosion-resistant piping. Learn about indirect waste receptors, neutralization, and the requirement that special waste be pretreated before entering the sanitary system.
Traps in Questions
Distractors connect storm drainage to the sanitary sewer where separation is required, or omit secondary drainage. Watch for questions on grease interceptor sizing and maintenance, and on whether a floor drain may discharge to a storm system. Another trap: assuming a roof drain needs no strainer or overflow.
Worked Example
Rule of thumb: "Two paths off the roof." Provide primary drainage plus a secondary means (overflow scuppers or a secondary system) sized for the design storm. If a question shows only one roof drain, look for the missing overflow.