107.The ratio of the lengths of the shortest flow path and the longest flow path must be at least 0.7, except if less than 20% of the surfaces drained to the dry retention system drain through the shortest flow path.
107.The ratio of the lengths of the shortest flow path and the longest flow path must be at least 0.7, except if less than 20% of the surfaces drained to the dry retention system drain through the shortest flow path.