A. 
Roofs, courts, paved areas in excess of 2,500 square feet and open shafts shall be drained into a public storm sewer system or a public combined sewer system, whenever such a system is available, or when such systems are unavailable, they shall be drained or conducted to a point of disposal approved by the Plumbing Inspector so as to:
(1) 
Protect the foundation of buildings from water damage.
(2) 
Prevent water accumulation on streets, sidewalks and other areas used for pedestrian or vehicular travel.
(3) 
Prevent water accumulation which may cause odors, breeding of insects or other health hazards.
(4) 
Prevent contamination of water supply systems.
B. 
Area drains may be required by the Plumbing Inspector in order to comply with Subsection A.
C. 
The rear yard of each lot must be provided with a suitable area drain for surface drainage as required in § 131-60.
D. 
Rainwater conductors may be connected with the stormwater upright of a hydrant area drain, provided that the area drain does not receive the discharge from waste pipes.
E. 
Traps. Leaders, yard drains, area drains and other storm drains connected to a combined sewer shall be effectively trapped, except that inside leaders connected to roof outlets not located directly below a door or window or other ventilating opening of the same or an adjacent building nor within 12 feet of such an opening may be without traps. Traps on leaders shall be deep-seal type, in accordance with § 131-29D.
F. 
Where an owner is required to abandon an individual sewage disposal system and connect to an available public sewer, the rain leaders of detached garages located on the same lot may be permitted to discharge to a point of disposal other than the public sewer, when requested by the property owner and provided that in each individual case, there shall be an inspection and approval by the Plumbing Inspector to determine that no nuisance or insanitary conditions may ensue.
G. 
Construction of stormwater catch basins. If construction is of the masonry type, it shall be of reinforced concrete, the base and walls shall be not less than six inches in thickness; or construction may be of eight-inch sewer brick parged to a smooth finish on the interior walls; or construction may be of eight-inch seventy-five-percent-solid concrete block parged to a smooth finish on the interior walls. Other materials may be used when approved by the Plumbing Inspector.
131i 88G.tif
A. 
Subsoil drains connected to street sewers or house drains shall discharge into and through a properly trapped sand interceptor.
B. 
Where subsoil drains are located below the sewer level they shall be in accordance with Subsection A. The stormwater shall be raised and discharged into the house drain by an automatically operated sump pump.
C. 
In a single-family dwelling, the subsurface water shall drain directly into an open sump and shall be raised by means of an automatically operated sump pump and shall discharge into an area drain, floor drain or laundry tub.
A. 
Stormwater shall not be drained into sewers intended only for sanitary sewage. Sanitary waste shall not be drained into sewers intended only for stormwater.
B. 
No soil stack, waste stack or vent stack shall also serve as a leader.
C. 
No leader shall also serve as a soil stack, waste stack or vent stack.
A. 
Inside leaders. Leaders within a building shall be of cast-iron pipe, either hub or hubless, galvanized steel pipe, galvanized wrought-iron pipe, galvanized yoloy pipe, galvanized malleable iron split couplings (victaulic), brass pipe, DWV or heavier copper tube, lead, stainless steel (409 Type G copper-coated), ABS or PVC plastic. All materials shall conform to § 131-13.
B. 
Outside leaders and downspouts. Outside leaders and downspouts may be of sheet metal but the connections to the house drain shall be cast-iron pipe extending vertically at least 18 inches above the grade level with tight connections between leader and soil pipe.
C. 
Underground storm drains. Storm drains, when underground within buildings and to a point 10 feet beyond the building walls, shall be hub-type cast-iron pipe or copper tube Type K, hard-temper. These materials will be installed with appropriate approved fittings complying with the specifications listed in § 131-13.
D. 
House storm drains. House storm drains, underground from a point 10 feet beyond the building wall shall be installed in accordance with § 131-82C and D. These materials shall be installed with appropriate fittings complying with the specifications in § 131-13. When installed in filled or unstable ground, the house storm drain shall be of cast iron or hard-temper copper of a weight not less than Type K.
E. 
ABS plastic and PVC plastic pipe shall be limited to installations of buildings containing dwelling units only, consisting of from one to four families and not over three stories in height. For the purpose of this subsection, basements are not considered a story height.
F. 
All underground stormwater piping installed parallel to a foundation wall shall be at least three feet from the building foundation wall when the depth does not exceed four feet one foot of additional distance from the foundation wall shall be required for each additional one foot of depth below four feet.
A. 
Vertical leaders.
(1) 
The minimum size of a vertical leader, including the horizontal offset at the top of the vertical leader draining a roof, shall be based on the horizontal roof area served by such leader, as given in the following Table L-1:
Table L-11
Maximum Horizontal Projected Roof Area for Building Storm Drains at Various Slopes
(square feet)
Fall Per Foot
(inches)
Diameter
(inches)
1/8
1/4
1/2
Vertical Leaders
3
930
1,300
1,750
4
1,585
2,100
3,300
3,650
5
2,875
3,800
5,300
6,800
6
4,300
6,000
9,000
10,800
8
9,200
13,000
18,000
23,000
10
16,500
25,000
35,000
40,000
12
26,600
40,000
60,000
65,000
15
47,500
75,000
100,000
115,000
16
57,250
92,500
131,000
18
67,000
110,000
162,000
20
85,500
135,000
196,000
24
155,000
225,000
30
295,000
416,000
NOTES:
1
Seeded areas shall be taken to equal 55% of the actual measured area.
(2) 
Where there is a continuous or semicontinuous discharge into the house storm drain, as from a bilge pump, ejector, air-conditioning equipment or similar device, each gallon per minute of such discharge shall be assumed to be equivalent to 14 square feet of roof area.
B. 
Storm drains. The minimum size of the house storm drain, or any of its branches, draining a roof or area drainage and with the pipe, having slopes indicated, shall be based upon the maximum roof area to be handled according to Table L-1. The main drain shall be graded at a fall of not less than 1/8 inch per foot except upon special permission of the Plumbing Inspector.
C. 
Canopies and marquees. Canopies, marquees and similar extended roof surfaces may be drained by two-inch leaders where construction does not permit the installation of larger pipe, if permission is obtained from the Plumbing Inspector. A three-inch trap and underground drain shall be provided.
D. 
Combined drainage piping.
(1) 
Where a combined main sewer is available, the house drain and house storm drain may be connected to a combined house drain or combined sewer.
(2) 
The size of the combined house drain shall be obtained from Table L-1 by adding to the square feet of stormwater drainage area an allowance in square feet for each fixture unit on the house drain. This allowance shall be determined in accordance with Table L-2 as follows:
Table L-2
Allowance of Pitched Roofs for Fixture Units
Allowance
(square feet)
Fixture Units
7 per unit
First 1,500
5 per unit
Next 1,500
4 per unit
Next 2,000
3 per unit
Over 2,000