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Plumbing Stormwater Questions and Answers, June 4, 2009 1. Do Commerce plumbing or POWTS reviewers and consultants enforce NR 151?No. However several plumbing code requirements are identical to NR 151 requirements such as a concern for maintenance. 2. When does a submittal require a maintenance plan? When the plumbing system drains one or more acres. This could be impervious or pervious. 3. When does a storm system require submittal? There are five requirements that mandate storm submittal. 1. Stormwater or Clearwater subsurface infiltration serving public buildings or facilities. 2. Plumbing storm use systems such as irrigation, toilet & urinal flushing, etc. (A POWTS is a reuse system, but it would be covered through Comm 83) 3. A storm systems serving a public building or facility that drains one acre or more. 4. Storm private interceptor main sewers that would be more than 4 inches in diameter when sized for gravity flow. 5. Storm system in association with a building where 16 or more plumbing fixtures are to be installed (fixtures include roof drains, area drain inlets, floor drains, hose bibbs and water heaters). Note: Check with Tables 82.20-1 & -2 for proper location for submittal. 4. If a residential subdivision has a storm private interceptor that will be turned over to the municipality prior to use, does Commerce need to approve it? No. 5. If an area has 1 acre or more drainage area and it’s not impervious, does it still need to be submitted? Yes, the submittal requirement is based on area discharging to the storm sewer, whether impervious or not. 6. Are wet detention basins plumbing? (See PDF drawings) The classic design of the detention basin is not plumbing. The plumbing system is affected by the basin because the downstream piping must be sized based on the outlet flow from the basin. See Comm 82.36(3), Wis. Adm. Code, for design requirements downstream of detention. 7. What if I completely fill a detention basin with rock and all the wastewater is subsurface? Then the basin becomes part of the plumbing system because the wastewater discharge and flow is designed to be subsurface. 8. When does a wastewater treatment device or method like a basin, detention chamber or other designed storm component (rock, grass strip, etc) need plumbing product review? Only when the product is upstream of a subsurface infiltration or reuse system. 9. When are rain gardens considered plumbing? At this time the department staff have never seen a rain garden that’s considered part of the plumbing system. In the future new designs may change that view. 10. Is a bioretention system a plumbing system component? Yes. A bioretention system is considered a plumbing infiltration and treatment system. The infiltration portion of the bioretention system requires plan review when installed to serve other than one- or two-family. The treatment portion also necessitates review when installed to serve as a pretreatment device to comply with Table 82.70 for a reuse system. 11. If a bioretention system serves several building sites (a subdivision) and is located on private property, does the system require plan review? Yes, because a subdivision is a public facility. See Table 82.20-1 12. Is a liner required when a subsurface detention system is installed? Yes, because it’s impossible to eliminate infiltration without the liner. Subsurface detention systems must be designed to contain wastewater until it is properly discharged. Without the liner, the system is also an infiltration system. 13. Does a liner require product review? No, because all the code requires is that the subsurface detention system is water tight. 14. What thickness of liner provides a water tight subsurface detention system? The depth of water and type of material determine whether or not a material is water tight. DNR acceptable lining materials used for ponds and land fills that may be appropriate. 15. Are there code requirements that prevent a storm plumbing system from causing damage to a building? Yes. Inlets and piping must be sized for anticipated flow at the 10-yr storm and designed so that no property damage occurs during the 100-year, 24-hour storm event. Table 82.38-1 only allows stormwater discharge where the water does not create a nuisance. 16. Do plumbing reviews include treatment devices required by NR 151.12? No. NR 151 rules are not enforced by plumbing plan reviewers. Plumbing reviews only include the review of treatment devices that are designed to comply with Table 82.70. 17. Does Commerce enforce the detention (discharge rates) requirements found in NR 151? No. 18. Will Commerce reviewers verify the discharge rate through the plumbing system from a site? Yes. If a designer requests verification of the plumbing (through the pipe) discharge rate, the plan reviewer will provide that service. 19. Will Commerce reviewer calculate the post development discharge allowance based on NR 151 and evaluate the plan to those requirements? No. Commerce will not assure compliance with another agency’s codes. 20. When is the piping, treatment or detention system considered plumbing? * Foundation and subsurface drains are not considered plumbing. * The point where plumbing begins is where a foundation/subsurface drain discharges to a sewer, sump or drain tile receiver. * A culvert located entirely on the right-of-way is not plumbing. * Surface ponds are not considered plumbing * A grass filter strip, basin or other constructed component may be part of a plumbing system; much like a POWTS mound or sand filter, and these devices may serve as plumbing treatment devices. * Gutters and downspouts are not plumbing. Pipe conveying stormwater from gutters and downspouts are plumbing. 21. Can infiltration overflow or subsoil drainage to the storm sewer system? Yes. The subsoil drain or infiltration overflow must discharge to a manhole or area drain inlet. The invert elevation (i.e.) of the storm pipe conveying the wastewater from the subsoil drain must enter the manhole or area drain inlet at a point higher than the discharge pipe. County Web sites || City/Town/Village Web sites || State Portal || Build Your Business Email this page's manager, Todd Taylor, ttaylor@commerce.state.wi.us or 608-267-3606 The Department of Commerce Safety and Buildings Division is an equal opportunity service provider and employer. If you need assistance to access services or need material in an alternate format, please contact us, 608-266-3151, TDD Relay dial 711 in Wisconsin or 800-947-3529, or ttaylor@commerce.state.wi.us |
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