Driveway Drainage and Trench Drains

Hello.

I am seeking your expertise for a driveway drainage situation. Currently, the driveway grade is pitched slightly toward the house, leading to seepage into the basement after rain events. The driveway is bounded by a garage at the top, a solid concrete porch to the east, and a property line/fence to the west.

A trench drain installation has been suggested. I would like to know what, in your opinion, is the better option for the water to run into: a) a dug out trench with 4"pvc pipe running 50'away from the garage and into a ravine or b) tying the trench drain into the existing storm sewer system. I am trying to assess on the pros and cons of both, including risk factors such as potential back-ups.

ANSWER

Not all townships allow to tie into storm water systems. If your town allows it, I would then assess the costs and ease of installation for both. Also, the beginning and end grades have to be determined to make sure the pipes can be pitched correctly. The minimum pipe slope should be 1/4" per foot. Some contractors work with less, but I am more comfortable with this pitch.

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See the following pages:
Trench Drains
Perforated Pipe

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With the option of using the storm water system, I am assuming you are talking about running the pipe from the trench drain directly to the basin at the street. If you are talking about connecting to sewer pipes exiting from your house, I would NOT tie into those. It's better to keep those separate from anything else!

I can't see why there would be any backup problems in either option (connecting to the street or leading the solid pipe out to the ravine) unless there is ever a crack in the pipe...as long as where the pipe exits is quite a bit above the bottom of either area (the storm basin or the ravine) and the slope is adequate.

Also, a 100 year storm is one that is expected to occur once in 100 years. In the event of a storm such as this, it would always be possible (worst, worst case scenario) for the storm basin to fill up or the ravine to reach the top with water and force it's way up the pipe. But with the proper slope and exit height at the end, this drainage system should work correctly.

If you have further questions, let me know.