I found it, under transportation, under snow heading, at the bottom of the page
http://www.philadelphiastreets.com/transportation-highways-snow-intro.aspx

If a Snow Emergency is Declared

As winter weather approaches, the Streets Department
monitors weather forecasts to provide advance notice of weather
conditions. When snow accumulations approach emergency status, the
Managing Director may declare a snow emergency. Stay tuned to local
radio and television news. If a Snow Emergency is declared, the City
will plow the 110 miles of snow emergency routes from curb-to-curb. This
means owners of vehicles and dumpsters must move them to alternate
parking spaces. Vehicles that cannot move under their own power are not
exempt. Vehicles and dumpsters cannot park on snow emergency routes
until the emergency has been declared over. Residents should look for
snow emergency route signs along streets where they work, live, or shop.
They are large signs reading “Snow Emergency Route” in white letters on a red background. Plan ahead for alternate parking accommodations.

Failure to move vehicles and dumpsters can result in a towing charge up to $150.00 or a substantial fine. If your vehicle has been towed from a Snow Emergency Route, call 215-686-SNOW, and be prepared to provide information to identify your vehicle. Citizens should NOT call 911.
Police Department dispatchers do not have information on vehicles towed
as a result of plowing operations. Motorists may drive on snow
emergency routes as long as their vehicles are equipped to handle
adverse conditions. Vehicles that stall or become stuck along snow
emergency routes are also subject to towing and fines. For more
information on Snow Emergency Routes click here.

Overview

Our Highway Unit is the primary response team during snow and ice
events. One of the major challenges the
unit incurs is snow being shoveled back into plowed streets after city
teams clear the street. This practice
is not only illegal, it’s a hazard to drivers and pedestrians. Another
challenge is cars parked too close to a corner,
which interfere with the turning radius of snow removal equipment.
Philadelphia Code 12-9131(1)(b)(iii) prohibits parking within 20 feet of
a crosswalk at an intersection.

SnowCat

SnowCat is a system that identifies various categories of weather
conditions and indicates the City’s response to each category. For information on SnowCat, call Customer Affairs: 215-686-5560 or click here. Citizens may also request a SnowCat booklet by calling Customer Affairs or visiting our download area.

Philadelphia Code 10-720 Regarding Snow Removal From Sidewalks

According to Philadelphia Code (10-720),

“(1) the owner, agent, and tenants of any
building or premise shall clear a path of not less than 36″ in width on
all sidewalks, including curb cuts, abutting the building or premises
within 6 (six) hours after the snow has ceased to fall. The path shall
be thoroughly cleared of snow and ice. Where the width of any pavement
measured from the property line to the curb is less than 3 (three) feet,
the path cleared may be only 12 inches in width. When the building in
question is a multifamily dwelling the owner or his agent shall be
responsible for compliance with the requirements of this section.”

(2) Snow or ice removed from sidewalks, driveways, or other areas shall not be placed or piled in the street.

(3) Any person who violates this Section shall be subject to the
provisions and penalties set forth in 10-718 and 10-719.

The penalty for violating this provision can range from “a
minimum fine of fifty dollars ($50) to no more than three hundred
dollars ($300) for each violation.”

Private plows piling snow in the street after city teams have
cleared the road is illegal as well as a hazard to drivers and
pedestrians.