Drain pipes below deck Draining into storm sewer
Many times, especially in urban areas, scuppers cannot be allowed to drain directly onto the ground or onto other roadways, buildings, etc. One method used to address these situations involves connecting the scuppers to lateral and vertical drain pipes which are designed to empty into storm drains. Make sure these drainpipes are free flowing and not plugged. Many times the laterals are too flat in slope and the elbows are 90 degrees which encourages plugging. It may be easier in some cases, rather than constantly trying to unplug these connections, to redesign the system with more slope on the laterals and elbows no greater than 30 degrees. By using readily available PVC and polyethylene piping and with a little ingenuity, these systems can be made more maintenance free. Transition connections from steel to plastic can be made using rubber sleeves and stainless steel clamps.
If the vertical drain pipes are directly connected to the storm drain system, consider making a discontinuity in the system at the ground line. The vertical pipe should be terminated one to two feet above the ground line, and a small catch basin installed below the end. This will allow easier cleanout and will minimize backup in the vertical pipe.