If a standpipe exceeds 80 feet above the highest service connection, it is no longer considered ground storage.

If a standpipe exceeds 80 feet above the highest service connection, it is no longer considered ground storage.

• A. It is still ground storage
• B. It is no longer ground storage
• C. It must be emptied
• D. It becomes a reservoir

Answer: (B)

Water storage classification depends on how high the water surface sits above the highest service connection. Ground storage is intended to be at or near grade, with the water surface not more than about 80 feet above the highest service connection. If a standpipe’s height puts the water surface more than 80 feet above that connection, the hydraulic conditions are different enough that the system is no longer considered ground storage and is treated as elevated storage (a standpipe) instead. The 80-foot rule roughly corresponds to about 34 psi of static head, which explains why the system behavior and design requirements change with greater height. So the correct conclusion is that it is no longer ground storage. The other options don’t fit because they either ignore the height-based classification, imply an action (emptying) that isn’t dictated by height, or mislabel the system type.

Water storage classification depends on how high the water surface sits above the highest service connection. Ground storage is intended to be at or near grade, with the water surface not more than about 80 feet above the highest service connection. If a standpipe’s height puts the water surface more than 80 feet above that connection, the hydraulic conditions are different enough that the system is no longer considered ground storage and is treated as elevated storage (a standpipe) instead. The 80-foot rule roughly corresponds to about 34 psi of static head, which explains why the system behavior and design requirements change with greater height. So the correct conclusion is that it is no longer ground storage. The other options don’t fit because they either ignore the height-based classification, imply an action (emptying) that isn’t dictated by height, or mislabel the system type.