Common Water Service Requirements in Illinois
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This post comes from Sean Fallows our Fire Protection Supervisor.
Common water services are becoming the go to design standard for incoming water services. This edition of access to answers is to explore the cause and effect of this design option.
The Illinois Plumbing Code and the Illinois Department of Public Health (IDPH) published a memorandum on water services attached to public water supplies (1). The memorandum clearly documents that a combined water service, serving both the fire protection systems and domestic system, or another engineered solution is required when connected to a public water main. This is to prevent fire protection supply lines from creating dead ends.
The Illinois Plumbing Code (IPC) states that a length of more than 2 feet is a dead end. Based on this existing language in the IPC a dedicated fire suppression water service line meets the definition of a dead end. The following information is based off the 2014 IPC and the 2015 Edition of the International Fire Code (IFC), but the principals are reflected in newer and older editions of the code.
When adopted, the IFC contains language that dictates the design, installation, and testing of water mains that serve a fire protection suppression system. The Fire Protection Water Supplies section of the IFC directs the designer to utilize the 2013 edition of NFPA 24 Standard for the Installation of Private Fire Service and Appurtenances (2). After a review of the requirements in IPC, IFC, and NFPA 24 the following conclusions are being brought to your attention for evaluation.
The first area of concern is the design and review process. The design of the combined water service will need to be reviewed based on the plumbing design and proposed fire sprinkler design. Plumbing plan reviews currently do not address the additional requirements laid out in NFPA 24. The additional information would need to be included in the civil, utility, plumbing, or a separate submittal.
Additionally, the Fire Sprinkler Contractor’s Licensing Act scope does not include the common water main and therefore a designer with NICET qualifications would be insufficient. The design is regulated by the Professional Engineering Practice Act for both the individual designer and the design firm. The design of the service must now comply with both standards (IPC and NFPA 24) which layout specific requirements for the materials that can be used for the underground water piping and materials (3).
While the two standards reference different years of the same standard the only standards that meet both requirements (IPC & NFPA 24 per the IFC) are Ductile Iron Pipe that meets AWWA C151 and Ductile Iron Fittings that meets AWWA C110, Polyethylene (PE) Pipe and Fittings that meets AWWA C906, and Polyvinyl Chloride (PVC) Pipe and Fittings that meets AWWA C900.
Additionally, the design must accommodate the stricter requirements for thrust blocking. While the IPC requires only support of the water filled pipe, NFPA 24 requires the materials and size are more specific. The size of the thrust blocks utilize reference tables or calculations to determine the size of the thrust blocking (4). The composition of the thrust blocks is required to be a specific mix of concrete.
Once the system is installed, the piping system must be inspected to both standards. The most stringent testing requires a Chlorination test per the IPC and a flushing and hydrostatic test per NFPA 24 (5). The NFPA 24 flush test is based on achieving 10 feet per second a seen in Table 10.10.2.1.3 or required fire sprinkler flow. The accompanying hydrostatic test is required to last 2 hours and be pressurized to at least 200 psi.
Footnotes:
(1) See code reference IPC 890.1200 c)
(2) See code reference IFC 507.2.1
(3) See code reference IPC 890 Appendix A Table A Approved materials for Water Service Pipe, Approved Standards for Fittings, NFPA 24 Table 10.1.1.1 and 10.2.1.1
(4) See code reference NFPA 24 Table A.10.8.2(b) for example block sizes (5) See code reference IPC 890.1180