All the bulkheads are on the same horizontal line.
Both the siphon and sec drains have turned down elbows at the same level but because air is allowed the enter the sec and water does not flow until the water line is up to the bulkhead, the sec is used to control the water level in the overflow box.
The emerg drain elbow is turned up and above the water level in the overflow box.
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Crap happens, that's why they sell toilet paper in 48 roll packs!
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