[Amended 9-7-2010 by Ord.
No. 24-10]
All roofs, paved areas, yards, courts, courtyards, or areas using a topping or finish capable of collecting water shall be drained into a separate storm sewer system, or a combined sewer system, as per §860-169E, where such systems are available. Alternatively, as a green initiative, structural and nonstructural stormwater management practices separate from a storm sewer or combination sewer may be employed as long as they comply with Document 363-0330-002, Best Management Practices for Storm Water Management, issued by the Pennsylvania Department of Environmental Protection, available electronically at http://elibrary.dep.state.pa.us, or are of a best management practice design that meets or exceeds the requirements of the above-noted document and meet the requirements of the Administrative Authority and the local municipality. If there is no storm or combined sewer available for such drains, or if an individual chooses to construct an alternative system specified above, then the water from said drains shall be conducted by proper pipe or pipes below the surface of the sidewalk, to the street gutter or to a place of disposal satisfactory to the Administrative Authority, where the local municipality has no ordinance or regulation in place, and in accordance with any other plans or ordinances adopted under the Storm Water Management Act, 1978, October 4, P.L. 864, No. 167,[1] or other ordinances or regulations of the municipality
involved. In no case shall collected surface water or stormwater be
allowed to drain over sidewalks or driveways, or onto adjacent properties
where the water can create soil erosion or have adverse effects on
a structure.
[1]
Editor's Note: See 32 P.S. § 680.1
et seq.
Storm water shall not be drained into sewers
intended for sewage only. Also, where infiltration of storm, ground,
or seepage water into the sanitary system exists, corrections to eliminate
this condition shall be made and is the responsibility of the owner
or his/her agent.
Storm drains, conductors, traps, fittings, etc., shall be of materials as provided for in Article V, "Materials, Standards and Areas of Permitted Use."
A.
Size of building storm drain. The size of the building
storm drain or any of its horizontal branches having a slope of 1/2
inch or less per foot, shall be based upon the maximum projected roof
or paved area to be handled according to the following Table 860-164A,
"Size of Horizontal Storm Drains."
|
TABLE 860-164A
Size of Horizontal Storm Drains
| |||||
|---|---|---|---|---|---|
|
Maximum roof and paved areas for drains
of various slopes
| |||||
|
Dia. of Pipe
(inches)
|
1/16" fall per ft.
Sq. ft.
|
1/8" fall per ft.
Sq. ft.
|
1/4" fall per ft.
Sq. ft.
|
1/2" fall per ft.
Sq. ft.
| |
|
*2
|
N.P.
|
N.P.
|
400
|
580
| |
|
*2
|
N.P.
|
N.P.
|
750
|
1,050
| |
|
3
|
N.P.
|
N.P.
|
1,160
|
1,644
| |
|
4
|
N.P.
|
1,880
|
2,650
|
3,760
| |
|
5
|
N.P.
|
3,340
|
4,720
|
6,680
| |
|
6
|
N.P.
|
5,350
|
7,550
|
10,700
| |
|
8
|
8,200
|
11,500
|
16,300
|
23,000
| |
|
10
|
14,800
|
20,700
|
29,200
|
41,400
| |
|
12
|
24,000
|
33,300
|
47,000
|
66,600
| |
|
15
|
42,000
|
59,500
|
84,000
|
119,000
| |
|
18
|
73,000
|
103,000
|
145,000
|
205,000
| |
|
21
|
110,000
|
155,000
|
220,000
|
312,000
| |
|
24
|
155,000
|
220,000
|
310,000
|
440,000
| |
|
27
|
215,000
|
304,000
|
430,000
|
610,000
| |
|
30
|
280,000
|
400,000
|
565,000
|
805,000
| |
|
33
|
360,000
|
520,000
|
730,000
|
1,000,000
| |
|
36
|
460,000
|
650,000
|
920,000
|
1,300,000
| |
|
42
|
700,000
|
990,000
|
1,390,000
|
1,900,000
| |
|
48
|
990,000
|
1,400,000
|
1,990,000
|
2,800,000
| |
|
NOTES:
| ||
|---|---|---|
|
*
|
Not permitted underground.
| |
|
N.P.
|
Not Permitted.
| |
B.
Size of vertical conductors. Vertical conductors shall
be sized on the maximum projected roof area, according to Table 860-164B,
"Size of Vertical Conductors."
|
Table 860-164B
Size of Vertical Conductors
| ||
|---|---|---|
|
Diameter of Leader Pipe
(inches)
|
Maximum Roof Area
(square feet)
| |
|
2
|
720
| |
|
2 1/2
|
1,300
| |
|
3
|
2,200
| |
|
4
|
4,600
| |
|
5
|
8,650
| |
|
6
|
13,500
| |
|
8
|
29,000
| |
C.
Size of combined sewers. To compute the size of a combined sewer the method of Subsection A shall be used. The fixture units shall be converted into an equivalent projected roof or paved area. When the total fixture unit load on the combined sewer is 256 fixture units or less, the equivalent drainage area in horizontal projection shall be taken as 1,000 square feet. When the total fixture load exceeds 256 units, each additional fixture unit shall be considered the equivalent of 3.9 square feet of drainage area.
D.
Values for continuous flow. Where there is a continuous
or semi-continuous discharge into the building storm drain or building
storm sewer, as from a pump, ejector, air-condition plant, controlled
flow roof drainage, or similar device, each gallon per minute of such
discharge shall be computed as being equivalent to 24 square feet
of roof or paved area.
Building subdrains located below the public
sewer level shall discharge into a sump or receiving tank the contents
of which shall be automatically lifted and discharged into the drainage
system as required for building sumps.
Every sump or receiving tank receiving the discharge of clear water such as rain water, subsoil or seepage drainage, shall be of materials as provided for in Article V, "Materials, Standards and Areas of Permitted Use."
A.
When subsoil drains are placed under the basement
floor or used to encircle the outer walls of a building, they shall
be protected by an accessibly located back water valve before connecting
to the building storm or combined drainage system. Where connected
to separate storm drainage system, and the connection is made on the
building side of the main leader trap, no other trap will be required
other than the back water valve, where the connection is made on sewer
side of main leader trap, they shall be effectively trapped, or they
may discharge into a properly trapped area drain or catch basin. Where
connected to a combined building drain, they may discharge through
a cellar or basement floor drain using a four inch running trap provided
with an accessibly located back water valve. These drains shall have
a connection of not less than four inches in diameter. The final connection
of the collected water with the storm or combination drainage system
shall require a plumbing permit and be inspected by the Department.
And when such drains are connected with the storm or combination system,
such connection shall be performed by a registered master plumber.
Where no storm or combined sewer is available, the water shall be
drained or pumped to a point of disposal satisfactory to the Administrative
Authority where the local municipality has no ordinance or regulations
in place.
B.
Piping used for the collection of subsoil or seepage drainage shall be of approved material as provided for in Article V, § 860-65D. The pipe shall be laid on no less than four inches and covered with no less than six inches of crushed stone or gravel of medium size and arrangements made to cover the pipe with a material to prevent, as much as possible, sand or dirt from washing into and clogging the stone or gravel bed and cover.
A.
Where required. Conductors and storm drains when connected
to a combined sewer or public storm sewer system shall be trapped.
B.
Where not required. No traps will be required for
storm water drains which do not connect to a public storm sewer or
combined sewer system.
C.
Trap material. Storm water traps when required shall
be of materials conforming to the type of piping material used, except
when underground they shall be of approved material. Traps for area
drains or catch basins shall be of approved material.
D.
Method of installation. Individual storm-water traps
shall be installed on the storm-water drain branch serving each conductor,
or a single trap shall be installed in the main storm drain at the
building wall before its connection with the combined building sewer,
or when independently connected to the public storm or combined sewer.
A.
Where required. All buildings shall be provided with
proper conductors for conducting the water from the roofs in such
manner as shall protect the walls and foundations of said buildings
from injury.
B.
Not to be used improperly. Conductor pipes shall not
be used as soil, waste, or vent pipes nor shall drainage or vent pipes
be used as conductors.
C.
Outside conductors and connections. Outside conductors
may be of sheet metal, or other approved material but they must connect
to the storm drainage piping by extending the pipe at least one foot
above grade level. All outside sheet metal conductors shall be connected
to the pipe as direct as possible, in a vertical position and no sheet
metal conductor shall be run horizontally across the outside walls
of a building.
D.
Protection of rain water conductors. Rain water conductors
installed along alley ways, driveways, or other locations where they
may be exposed to damage shall be protected by metal guards, recessed
into the wall, or be constructed of galvanized steel pipe to a height
which will afford the necessary protection.
E.
Combining storm with sanitary drainage. The sanitary
and storm drainage system of a building shall be entirely separate,
except that where a combined sewer is available, the building storm
sewer may be connected in the same horizontal plane through a single
wye fitting to the sanitary sewer. Such connection shall be made downstream
of the sanitary building trap at or beyond the properly line or at
a location approved by the Authority.
No portion of the storm drainage system installed
underground or below a basement or cellar shall be less than three
inches in diameter. Outside underground storm sewers shall be a minimum
of four inches in diameter.
A.
Material of roof drains. Roof drains shall be of materials as provided for in Article V, "Materials, Standards and Areas of Permitted Use."
B.
Roof drain strainers, general use. All roof areas,
except those draining to hanging gutters, shall be equipped with roof
drains having strainers extending not less than four inches above
the surface of the roof immediately adjacent above roof level, of
not less than 1 1/2 times the area of the conductor to which
the drain is connected.
C.
Flat decks. Roof drain strainers for use on sun decks,
parking decks, and similar areas, normally serviced and maintained,
may be of the flat surface type, level with the deck and shall have
an available inlet area not less than two times the area of the conductor
to which the drain is connected.
D.
Roof drain flashings required. The connection between
roofs and roof drains which pass through the roof and into the interior
of the building shall be made watertight by use of proper flashing
material.
Expansion joints or sleeves shall be provided
where warranted by temperature variations or physical conditions,
such types of joints or connections shall be subject to the approval
of the Administrative Authority.
Where separate systems of sanitary drainage
and storm drains are installed in the same property, the storm and
sanitary building sewers may be laid side by side in the same trench.
In lieu of sizing the storm drainage system
from conventional methods as previously described in this Chapter,
the roof drainage may be sized on controlled flow and storage of the
storm water on the roof provided the following conditions are met:
A.
The water of a 100-year frequency storm is not stored
on the roof for more than 24 hours.
B.
The water depth on the roof does not exceed three
inches during the above storm.
C.
The roof is dead level and 45-degree cants are installed
at any wall or parapet.
D.
Roof design for control-flow roof drainage shall be
based on a minimum of 30 pounds per square foot loading to provide
a safety factor above the 15 pounds per square foot represented by
the three-inch design depth of water. This factor should definitely
be kept in mind as a prime requirement for assuring a structurally
sound roof.
E.
Flashing extends at least 6" above the roof level
and scuppers are placed in the parapet wall 3 1/2 inches above
the roof level.
F.
No less than two drains are installed in roof areas
10,000 square feet or less and at least four drains in roof areas
over 10,000 square feet.
G.
Control of runoff from flat roofs shall be by proportional
weirs; no valves or mechanical devices shall be permitted.
H.
Drainage from control flow which is based on gallons per minute of flow shall be converted to equivalent square feet of roof or paved area, on the basis of each gallon per minute of flow being equivalent to 24 square feet of area as provided in § 860-164D, Drains not equipped with weirs, such as area drains, may be connected to the controlled flow system, provided the square feet of area, including the converted gallons per minute flow to square feet are added together and the drain is sized to convey the sum of all loads in accordance with Tables 860-164A, "Size of Horizontal Storm Drains," and Table 860-164B, "Size of Vertical Conductors."
