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Lot Drainage

Lot grading refers to the shaping or sloping of land elevations to ensure that surface runoff from storm events or snow melt is directed away from buildings towards a City street or lane and into the City’s storm sewer system. Lots are graded according to engineered lot grading plans which identify the lot grading style and design elevations for the front and rear property line. It is essential to establish and maintain the design elevations along shared rear and side property lines to ensure proper lot grading that is consistent with the lot grading plans, otherwise flooding may occur.

Lots developed prior to 1975 do not have engineered lot grading plans but do have back lanes which are designed to drain to the street or storm sewer catch basins. These lots are sloped to drain to the street or back lane.

The four most common lot grading styles are:

 
  1.  Back to Front Drainage (Type A) – The rear property line is the highest elevation on the lot. Surface drainage is directed to side property line swales which are sloped to drain to the front street.
  2. Front to Back Drainage (Type C) – The front property line is the highest elevation on the lot. Surface drainage is directed to side property line swales which are sloped to drain to the rear property line.
  3. Split Drainage (Type D) - The midpoint is the highest elevation on the lot. Surface drainage is directed to the street and to the rear property line.
  4. Walkout Basement (Type E) - The front of the building is the highest elevation on the lot. Surface drainage is directed to the street and to the rear property line.

 

City Lot Grading Plans