offsite and on site drainage area map

[pmurt]

for roadway drainage design, how to define offsite drainage areas and on site drainage areas? what are their differences?
will runoff from offsite drainage area be collected and flow into on site storm sewer systems at the end?

 

[cvg]

for roadway drainage design, on-site is within the property or right of way - that is, any rain that hits the pavement or shoulders or medians should be conveyed within the street right of way without flooding nearby adjacent property
off-site is from other adjacent properties and runs through your property
off-site runoff is not generally mixed with on-site runoff

 

[beej67]

Do your best to catch offsite water in headwalls or pedestal top inlets before it runs into the curb, or you'll kill yourself on gutter spread.

That's a lesson that most young civil site designers have to learn the hard way.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com