Heads up: There are no amended sections in this chapter.
Roofs, paved areas, yards, courts, and courtyards shall be drained to either a storm sewer where available, a combined sewer where necessary, or to a place of disposal satisfactory to the Authority Having Jurisdiction.
EXCEPTION: Storm water from one- and two-family dwellings may be discharged on lawns or streets provided that the storm water flows away from the dwelling and does not otherwise create a nuisance.
Storm water shall not be drained into sewers intended for sewage only, except as required by the Authority Having Jurisdiction.
Comment 1: The peak storm water flows in combined sanitary and storm sewer systems can overload the sewage treatment facility, causing it to bypass untreated sewage into its point of discharge.
Comment 2: In many cities with combined sewers, it is impractical to install separate sewers in the downtown areas because of the number of existing utilities under the streets.
Comment 3: Some jurisdictions with combined sewers require that new or renovated buildings have separate sanitary and storm building drains so that they could be connected to separate sewers in the future.
Where separate systems of sanitary drainage and storm water are installed in the same property, the storm and sanitary building sewers and drains may be laid side by side in the same trench.
  • a. Foundation drains shall be provided in accordance with the building subcode.
  • b., c. and d. DELETED
  • e. Where foundation drains are below the required point of discharge, one or more automatic sump pumps shall be provided. The pump or pumps shall have adequate capacity to convey all drainage to its point of discharge. The minimum pump capacity shall be 15 gallons per minute at the required discharge head. Sump pits shall be sized to accommodate the pump(s), as recommended by the pump manufacturer, but shall be not less than 15 inches in diameter nor less than 18 inches deep. Sump pits shall be provided with fitted covers. Pits shall be located to avoid foot traffic where their covers do not have sufficient strength to carry such weight. Discharge lines from sump pumps shall be sized according to the design pump capacity and shall be not less than 1-1/4" pipe size. A check valve shall either be incorporated into each sump pump or be installed in the discharge line from each sump pump, except that check valves may be eliminated where the discharge pipe would be subject to freezing. Under such conditions, the sump pit shall be adequately sized to prevent short cycling of the pump.
  • f. Where sump pumps discharge at grade on unpaved surfaces, the discharge pipe shall extend to a splash block or equivalent, which shall be designed to contain the discharge, reduce its velocity, and avoid disturbing adjacent areas. Where necessary, the discharge pipe shall terminate with an elbow to direct the flow along the splash block. Splash blocks shall be at least 24 inches long.
  • g. Water-operated sump pumps shall comply with Section 3.1.13.
See Figures 13.1.5-A and 13.1.5-B
Figure 13.1.5 - A
A FOUNDATION DRAIN OUTSIDE OF A FOOTING
Figure 13.1.5 - B
A SUMP PUMP FOR FOUNDATION DRAINS
  1. Drainage shall be provided for open areaways below grade where storm water may accumulate. Areaways include outdoor spaces that provide access to basements or floor levels of a building that are below grade. Drains in such areas shall be sized according to Table 13.6.2 and shall include strainers as required for roof drains or floor drains.
  2. Drains for individual areaways that collect rainwater from more than 100 square feet of space shall not be connected to a foundation drain.
See Figures 13.1.6 and 1.2.6
Figure 13.1.6
THE ARRANGEMENT OF AN AREAWAY DRAIN
Window wells shall be drained as required for areaways, except that window wells not greater than 10 square feet in area shall be permitted to drain into a foundation drain, either directly by means of a 2" minimum size drain, or indirectly through a porous filter bed.
See Figures 13.1.7-A and 13.1.7-B
Figure 13.1.7-A
A WINDOW WELL DIRECTLY DRAINED
Figure 13.1.7-B
A WINDOW WELL INDIRECTLY DRAINED
Storm water drainage from parking and service garages shall be in accordance with Sections 6.3.1.c, d, and e.
Trench drains shall be installed in accordance with the manufacturer's instructions for excavation, anchoring, assembly, and the connection of piping.
Roof areas of buildings shall be drained by roof drains or scuppers unless gutters and downspouts or other non-plumbing drainage is provided. The location and sizing of roof drains and scuppers shall be coordinated with the structural design and slope of the roof. Rainfall rates shall be applied so that the applicable rainfall rate for Burlington and Ocean counties and all counties south shall be six inches per hour and for Mercer and Monmouth counties and all counties north, the applicable rainfall rate shall be five inches per hour.
  1. Where parapet walls extend or other construction extends above the roof, creating areas where storm water would become trapped if the primary roof drainage system failed to provide sufficient drainage, an overflow roof drainage system consisting of suppers, standpipes, or roof drains shall be provided. The capacity of the primary system shall not be considered in the sizing of the overflow system.
  2. Where overflow drainage is provided by means of roof drains or standpipe, the overflow system shall be permitted to connect to the primary roof drainage system.
  3. Where overflow roof drainage is provided, the overflow level(s) into the overflow system shall be established by the amount of ponding that is allowed in the structural design of the roof, including roof deflection. An allowance shall be made to account for the required overflow head of water above the overflow inlets. The elevation of the overflow inlet plus the required overflow head shall not exceed the maximum allowable water level on the roof.
Where vertical walls drain onto roofs, an allowance based on 50% of the maximum projected wall area shall be added to the roof area onto which each wall drains.
When approved by the Authority Having Jurisdiction, the requirements of Sections 13.1.10.1 and 13.1.10.2 shall not preclude the installation of an engineered roof drainage system that has sufficient capacity to prevent water from ponding on the roof in excess of that allowed in the roof structural design during a 100-year, 15-minute storm.
Where continuous flow from a spring or ground water is encountered in a foundation drainage system or other subsoil drain, the discharge shall be piped to a storm sewer or approved water course.
Where foundation drains, areaway drains, window well drains, or other storm water drains discharge by gravity and are subject to backflow from their point of discharge, a backwater valve shall be provided in the discharge line. Backwater valves shall comply with the requirements of Section 5.5.
  1. Water-operated sump pumps shall not be used as a primary sump pump. They shall be secondary to an electric-powered sump pump.
  2. Backflow protection for the water supply to a water-operated sump pump shall comply with Section 10.5.13.d.
Materials for storm drain piping shall comply with Section 3.7 and Table 3.7.
  1. Traps shall be installed in a storm drainage system if it connects to a combined sewer conveying both sewage and storm water.
    EXCEPTION: Traps shall not be required where roof drains, rain leaders, and other storm water inlets are at locations allowed under Section 12.4.4 for outdoor vent terminals.
  2. Floor drains or other receptors within a building shall be individually trapped and vented if they are connected to a storm drainage system, regardless of whether or not the sewer is combined. The vent piping shall terminate outdoors, independent of any sanitary drain vent piping.
  3. Traps required under this section shall comply with the requirements of Section 5.3.
  4. Traps in stormwater piping shall have an accessible cleanout for its inlet, or other means of clearing the trap.
Where traps are required under Section 13.3.1, they shall be installed either on individual branches of the storm drainage system or in the building storm drain before it connects to the combined sewer. Traps shall not be installed in locations where they will be subject to freezing. Where traps are required for rain leaders, the minimum earth cover shall be as required in Section 2.16.
Stormwater conductors shall not be connected to sanitary drain or vent pipes nor shall sanitary drain or vent pipes be connected to stormwater conductors.
EXCEPTION: For combined building drains and combined sewers.
Rainwater leaders installed along alleyways, driveways, or other locations where they may be exposed to damage shall be protected by metal guards, shall be recessed into the wall, or shall have a cast iron or aluminum downspout boot extending not less than five (5) feet above grade. See Figure 13.4.2
Figure 13.4.2
PROTECTION OF RAINWATER LEADERS
  1. Storm and sanitary drainage shall not be combined unless connection to a combined sewer is required by the Authority Having Jurisdiction. Where a combined building drain is required for connection to a combined building sewer, the storm drains shall connect horizontally to the combined building drain through single wye fittings that are at least 10 feet downstream from the base of any drain stack. See Figures 13.4.3 and 1.2.15.
    Comment 1: The "10 feet downstream" requirement allows the sanitary discharge to stabilize before mixing with the storm water flow. It also reduces the backpressure on the sanitary drainage system that may be caused by heavy storm water discharges.
    Comment 2: The horizontal wye connection between the two drainage systems permits the flows to mix more uniformly without blocking the drain.
  2. Horizontal storm drain piping from vertical stormwater conductors shall be not less than 10 feet in length and shall be increased one pipe size larger than required for horizontal storm drains in Table 13.6.2 when it is less than 10 feet from its connection to a combined building drain.
Figure 13.4.3
A TRAP IN A STORM DRAINAGE SYSTEM CONNECTED TO A COMBINED SEWER
Double pattern fittings shall not be used to connect storm drains to combined building drains or combined sewers.
Comment: Double pattern fittings are not permitted to connect storm drains to a combined drain because the heavy flow in one drain branch may cause backpressure in the other drain branch.
Roof drains shall comply with ASME A112.6.4 and be constructed of corrosion-resisting materials. Drains shall include any deck clamps or other appurtenances necessary for installation and coordination with the roofing system.
Roof areas shall be drained to roof drains having raised dome strainers with dome free areas complying with ASME A112.6.4 for general purpose roof drains and for gutter or cornice roof drains.
EXCEPTIONS:
  1. Pitched roofs draining to hanging gutters.
  2. Roof areas subject to pedestrian and/or vehicular traffic.
Roof drains on patios, sun decks, parking decks, and other areas subject to pedestrian and/or vehicular traffic shall have flat grates with a free inlet area complying with ASME A112.6.4 for parapet roof drains and for promenade or deck roof drains. Such drains shall not be located where they cannot be readily inspected and maintained on a regular basis.
The connection between roofs and roof drains that pass through the roof and into the interior of the building shall be made watertight by the use of proper flashing material.
The roof drain size shall not be restricted by insertion of any roofing material or other means of channeling water flow into the drain.
  1. The outlet pipe size of roof drains having vertical outlets shall be not less than the size required for vertical storm drains in Table 13.6.1.
  2. The outlet pipe size for roof drains having horizontal outlets shall be not less than the pipe size required for horizontal storm drains in Table 13.6.2.
  1. Vertical storm drain piping shall be sized according to Table 13.6.1.
  2. Where a vertical pipe section is smaller than the following horizontal pipe section, the increase in size shall be made in the vertical pipe section.
  3. Where a vertical pipe section is smaller than the preceding horizontal pipe section, the reduction in size shall be made in the vertical pipe section.
    Table 13.6.1
    SIZE OF VERTICAL STORM DRAIN PIPING
    Nominal Diameter (inches) Flow Capacity (GPM) Allowable Projected Roof Areas (sq ft)
    at Various Rates of Rainfall per Hour (inches)
    1" 2" 3" 4" 5" 6"
    2" 23 2,180 1,090 727 545 436 363
    3" 67 6,426 3,213 2,142 1,607 1,285 1,071
    4" 144 13,840 6,920 4,613 3,460 2,768 2,307
    5" 261 25,094 12,547 8,365 6,273 5,019 4,182
    6" 424 40,805 20,402 13,602 10,201 8,161 6,801
    8" 913 87,878 43,939 29,293 21,970 17,576 14,646
    10" 1655 159,334 79,667 53,111 39,834 31,867 26,556
    12" 2692 259,095 129,548 86,365 64,774 51,819 43,183
    15" 4880 469,771 234,886 156,590 117,443 93,954 78,295
        7" 8" 9" 10" 11" 12"
    2" 23 311 272 242 218 198 182
    3" 67 918 803 714 643 584 536
    4" 144 1,977 1,730 1,538 1,384 1,258 1,153
    5" 261 3,585 3,137 2,788 2,509 2,281 2,091
    6" 424 5,829 5,101 4,534 4,080 3,710 3,400
    8" 913 12,554 10,985 9,764 8,788 7,989 7,323
    10" 1655 22,762 19,917 17,704 15,933 14,485 13,277
    12" 2692 37,014 32,387 28,788 25,910 23,554 21,591
    15" 4880 67,110 58,721 52,197 46,977 42,706 39,146
    NOTES FOR TABLE 13.6.1
    1. Flow capacities are based on stacks flowing 7/24 full.
    2. Interpolation between rainfall rates is permitted.
  1. Horizontal storm drain piping shall be sized according to Table 13.6.2 — Part 1 or Part 2. Such piping includes horizontal offsets in vertical storm drains, building storm drains, building storm sewers, and branches thereof.
  2. The design flows in Table 13.6.2 — Parts 1 and 2 are based on fairly rough pipe with a Manning friction coefficient "n" = 0.015.
Table 13.6.2 Part 1
SIZE OF HORIZONTAL STORM DRAIN PIPING (for 1"/hr to 6"/hr rainfall rates)
Size of Drain (inches) Design Flow of Drain Allowable Projected Roof Area at Various Rates of Rainfall per Hour (Square Feet of Roof)
Slope 1/16 inch/foot
Size GPM 1"/hr 2"/hr 3"/hr 4"/hr 5"/hr 6"/hr
2              
3              
4 53 5,101 2,551 1,700 1,275 1,020 850
5 97 9,336 4,668 3,112 2,334 1,867 1,556
6 157 15,111 7,556 5,037 3,778 3,022 2,519
8 339 32,629 16,314 10,876 8,157 6,526 5,438
10 615 59,194 29,597 19,731 14,798 11,839 9,866
12 999 96,154 48,077 32,051 24,039 19,231 16,026
15 1812 174,405 87,203 58,135 43,601 34,881 29,068
Slope 1/8 inch/foot
Size GPM 1"/hr 2"/hr 3"/hr 4"/hr 5"/hr 6"/hr
2              
3 35 3,369 1,684 1,123 842 674 561
4 75 7,219 3,609 2,406 1,805 1,444 1,203
5 137 13,186 6,593 4,395 3,297 2,637 2,198
6 223 21,464 10,732 7,155 5,366 4,293 3,577
8 479 46,104 23,052 15,368 11,526 9,221 7,684
10 869 83,641 41,821 27,880 20,910 16,728 13,940
12 1413 136,002 68,001 45,334 34,000 27,200 22,667
15 2563 246,689 123,345 82,230 61,672 49,338 41,115
Slope 1/4 inch/foot
Size GPM 1"/hr 2"/hr 3"/hr 4"/hr 5"/hr 6"/hr
2 17 1,636 818 545 409 327 273
3 50 4,813 2,406 1,604 1,203 963 802
4 107 10,299 5,149 3,433 2,575 2,060 1,716
5 194 18,673 9,336 6,224 4,668 3,735 3,112
6 315 30,319 15,159 10,106 7,580 6,064 5,053
8 678 65,258 32,629 21,753 16,314 13,052 10,876
10 1229 118,292 59,146 39,431 29,573 23,658 19,715
12 1999 192,404 96,202 64,135 48,101 38,481 32,067
15 3625 348,907 174,454 116,302 87,227 69,781 58,151
Slope 1/2 inch/foot
Size GPM 1"/hr 2"/hr 3"/hr 4"/hr 5"/hr 6"/hr
2 24 2,310 1,155 770 578 462 385
3 70 6,738 3,369 2,246 1,684 1,348 1,123
4 151 14,534 7,267 4,845 3,633 2,907 2,422
5 274 26,373 13,186 8,791 6,593 5,275 4,395
6 445 42,831 21,416 14,277 10,708 8,566 7,139
8 959 92,304 46,152 30,768 23,076 18,461 15,384
10 1738 167,283 83,641 55,761 41,821 33,457 27,880
12 2827 272,099 136,050 90,700 68,025 54,420 45,350
15 5126 493,379 246,689 164,460 123,345 98,676 82,230
NOTES FOR TABLE 13.6.2 — Part 1
  1. Design flows are based on fairly rough pipe with a Manning friction coefficient of n = 0.015
Table 13.6.2 Part 2
SIZE OF HORIZONTAL STORM DRAIN PIPING (for 7"/hr to 12"/hr rainfall rates)
Size of Drain (inches) Design Flow of Drain Allowable Projected Roof Area at Various Rates of Rainfall per Hour (Square Feet of Roof)
Slope 1/16 inch/foot
Size GPM 7"/hr 8"/hr 9"/hr 10"/hr 11"/hr 12"/hr
2              
3              
4 53 729 638 567 510 464 425
5 97 1,334 1,167 1,037 934 849 778
6 157 2,159 1,889 1,679 1,511 1,374 1,259
8 339 4,661 4,079 3,625 3,263 2,966 2,719
10 615 8,456 7,399 6,577 5,919 5,381 4,933
12 999 13,736 12,019 10,684 9,615 8,741 8,013
15 1812 24,915 21,801 19,378 17,441 15,855 14,534
Slope 1/8 inch/foot
Size GPM 7"/hr 8"/hr 9"/hr 10"/hr 11"/hr 12"/hr
2              
3 35 481 421 374 337 306 281
4 75 1,031 902 802 722 656 602
6 223 3,066 2,683 2,385 2,146 1,951 1,789
8 479 6,586 5,763 5,123 4,610 4,191 3,842
10 869 11,494 10,455 9,293 8,364 7,604 6,970
12 1413 12,429 17,000 15,111 13,600 12,364 11,334
15 2563 35,241 30,836 27,410 24,669 22,426 20,557
Slope 1/4 inch/foot
Size GPM 7"/hr 8"/hr 9"/hr 10"/hr 11"/hr 12"/hr
2 17 234 205 182 164 149 136
3 50 688 602 535 481 438 401
4 107 1,471 1,287 1,144 1,030 936 858
5 194 2,668 2,334 2,075 1,867 1,698 1,556
6 315 4,331 3,790 3,369 3,032 2,756 2,527
8 678 9,323 8,157 7,251 6,526 5,933 5,438
10 1229 16,899 14,787 13,144 11,829 10,754 9,858
12 1999 27,486 24,051 21,378 19,240 17,491 16,034
15 3625 49,844 43,613 38,767 34,891 31,719 29,076
Slope 1/2 inch/foot
Size GPM 7"/hr 8"/hr 9"/hr 10"/hr 11"/hr 12"/hr
2 24 330 289 257 231 210 193
3 70 963 842 749 674 613 562
4 151 2,076 1,817 1,615 1,453 1,321 1,211
5 274 3,768 3,297 2,930 2,637 2,398 2,198
6 445 6,119 5,354 4,759 4,283 3,894 3,569
8 959 13,186 11,538 10,256 9,230 8,391 7,692
10 1738 23,898 20,910 18,587 16,728 15,208 13,940
12 2827 38,871 34,012 30,233 27,210 24,736 22,675
15 5126 70,483 61,672 54,820 49,338 44,835 41,115
NOTES FOR TABLE 13.6.2 — Part 2
  1. Design flows are based on fairly rough pipe with a Manning friction coefficient of n = 0.015.
  1. Area drains and trench drains shall comply with ASME A112.6.3.
  2. Top loading classifications shall be light duty, medium duty, heavy duty, extra heavy duty, or special duty, based on their required safe live load.
The free area of the top grate for area drains and trench drains shall comply with ASME A112.6.3 based on their outlet connection size.
Where subject to debris passing through their grate, area drains and trench drains shall include a secondary strainer or sediment bucket.
Continuous or intermittent flows from a sump pump, air conditioning condensate drain, or other approved discharge into a storm drainage system shall be determined in gallons per minute flow. Air conditioning condensate drainage shall be based on not less than 0.006 gpm/ton of cooling capacity. Such flows shall be added to the stormwater load on the storm drainage system, which shall also be determined on the basis of gallons per minute according to 5 IN/HR = 0.052 GPM/SF and 6 IN/HR = 0.062 GPM/SF.
  1. Special design plumbing systems for stormwater in Appendix E include the following:
    1. siphonic roof drainage - Section E.9
    2. controlled flow roof drainage - Section E.10
  2. Special design plumbing systems are subject to the requirements of Sections E.1, E.2, E.3, and E.4. The design shall be subject to review and acceptance by the Authority Having Jurisdiction.
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