Philadelphia Code Subcode P, § 1101 GENERAL
SECTION 1101 GENERAL
1101.1 Scope. The provisions of this chapter shall govern the materials, design, construction and installation of storm drainage.
P-1101.1.1 Private building storm sewer. Repairs to existing private building storm sewer pipe materials shall be in accordance with Table P-1102.4. New or extended private building storm sewers may not cross any adjoining property except when included as part of an approved post construction Storm Water Management Plan in accordance with Philadelphia Water Department regulations or private storm sewer infrastructure designed in accordance with Section P-1115.
P-1101.2 Disposal. All Rrainwater from roofs and storm water from paved areas, yards, courts and courtyards shall drain to an approved place of disposal. For one- and two-family dwellings, and where approved, storm water is permitted to discharge onto flat pervious areas, such as streets or lawns, or area drains provided that the storm water flows away from the building.
P-1101.2.1 Area drain. Area drains shall be provided on all premises in the locations required by items 1 through 6 below:
1. Paved areas, courts, open shafts in excess of 5,000 square feet.
2. Driveways of any area which slope downward toward the building.
3. Terrain which slopes downward toward the building within 10 feet of the building's exterior walls.
4. Terrain which creates a low elevation such that standing water is possible.
5. Terrain which slopes downward toward adjacent property in such a manner as to concentrate the flow of runoff.
Exception: Where terrain slopes toward a natural watercourse such as a creek, stream or river, an area drain shall not be required.
6. At the low point of any swales on the property.
Exception: Where terrain slopes toward a natural watercourse such as a creek, stream or river, an area drain shall not be required.
* * *
P-1101.3 Prohibited drainage. Storm water shall not be drained into sewers intended for sewage only.
Exceptions:
1. Drains contained in enclosed parking garage not exposed to the outside climatic elements.
2. Drains receiving washdown, soil, oil, fat/grease or any other hazardous waste.
* * *
[BS]1 P-1101.7 Roof design. Roofs shall be designed for the maximum possible depth of water that will pond thereon as determined by the relative levels of roof deck and overflow weirs, scuppers, edges or serviceable drains in combination with the deflected structural elements. In determining the maximum possible depth of water, all primary roof drainage means shall be assumed to be blocked. The maximum possible depth of water on the roof shall include the height of the water required above the inlet of the secondary roof drainage means to achieve the required flow rate of the secondary drainage means to accommodate the design rainfall rate as required by Section 1106.
Exception: Canopies, marquees, balconies, and similar extended roof surfaces with a total of 300 square feet or less, shall not require drainage unless the areas include a parapet.
* * *
P-1101.9 Backwater valves. Storm drainage systems shall be provided with backwater valves as required for sanitary drainage systems in accordance with Section 714. For building sub-drains that service fixtures below the fresh air inlet termination that discharges into the building gravity drainage system by automatic pumping equipment, the required check valve installed with the pump shall provide sufficient means of protection against backflow.
Exception: Storm drainage systems and private on-site stormwater management systems located outside the 100-year floodplain or connected to the public storm sewer.