Skip navigation Wisconsin State Legislature
Note: A model that calculates peak flow such as SWMM, TR-20, TR-55, P8 or an equivalent methodology may be used.
(b) Volume. The volume of stormwater influent to a plumbing system shall be based on an analysis provided by a Wisconsin registered architect, registered professional engineer, or permitted designer of engineering systems – plumbing, or an approved alternate standard per s. SPS 381.20 (2) and a minimum of a two-year, 24-hour storm event and designed so that no property damage occurs at 100-year, 24-hour storm event with a Type II distribution.
Note: For runoff coefficients and use of other methods or models, refer to ch. SPS 382 Appendix A-382.36 (5)-2 and A-382.36 (5)-3.
Note: The intensity of rainfall varies considerably during a storm as well as geographic regions. To represent various regions of the United States, the U.S. Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) developed four synthetic 24-hour rainfall distribution types from available National Weather Service (NWS) duration-frequency data (Hershfield 1961; Frederick et al., 1977) or local storm data. Type IA is the least intense and type II is the most intense short duration rainfall. Types I and IA represent the Pacific maritime climate with wet winters and dry summers. Type III represents Gulf of Mexico and Atlantic coastal areas where tropical storms bring large 24-hour rainfall amounts. Type II represents the rest of the country, including Wisconsin. For more information, see the USDA-NRCS webpage: http://www.nrcs.usda.gov/.
(c) Additional inputs to stormwater systems. Additional inputs to stormwater systems shall be estimated based on anticipated flows and volumes.
(6) Conveyance and detention systems.
(a) Design. The design of stormwater and clearwater conveyance systems shall conform to all of the following:
1. Horizontal stormwater conveyance piping shall be sized using either of the following:
a. An engineering analysis, based on full flow capacity, acceptable to the department.
b. Tables 382.36-1 to 382.36-5 based on pipe type, diameter and pitch.
2.
a. A vertical conductor for stormwater may not be smaller than the largest horizontal branch discharging into the conductor.
b. Vertical conductors shall be sized in accordance with Tables 382.36-1 and 382.36-3 or by an engineering analysis acceptable to the department.
Note: For the use of Baird’s equation, refer to ch. SPS 382 Appendix A-382.36 (6)-1.
3. Clearwater conveyance systems shall be sized in accordance with s. SPS 382.30 (3) and (4).
4. Underground, gravity-flow storm building sewers shall have a minimum 3-inch inside diameter.
(b) Velocity in stormwater conveyance system piping. The pitch of stormwater conveyance system piping shall be designed to create a minimum velocity of one foot per second when flowing full.
(c) Fittings and connections.
1. Except as provided in subd. 2., fittings and connections for stormwater and clearwater conveyance systems shall comply with s. SPS 382.30 (8) and (9).
2. The minimum radius for the first 90° fitting located downstream of a roof drain shall comply with the horizontal to vertical requirements in Table 382.30-4.
(d) Stack offsets. Stack offsets for piping of a clearwater conveyance system piping shall comply with s. SPS 382.30 (6).
(e) Pitch of clearwater gravity conveyance system piping.
1. The minimum pitch of gravity conveyance system piping having a 2-inch inside diameter or less shall be 1/8 inch per foot.
2. The minimum pitch of clearwater gravity conveyance system piping having at least a 3-inch inside diameter or more shall be 1/16 inch per foot.
(f) Branch connections near base of stack. Branch drains from interior clearwater inlets may not connect downstream from the base fitting or fittings of a drain stack within a distance equal to 20 pipe diameters of the building drain.
(g) Detention systems.
1. The storage volume of a dry detention system shall be designed and installed with a drain time of 72 hours after a storm event.
2. Paved surfaces or parking lots serving as detention areas shall be limited to a design depth of 6 inches, unless otherwise limited by local ordinance.
3. By design, ground surface ponding shall drain within 24 hours after a storm event.
4. A subsurface stormwater detention system that has a permanent pool of water shall be designed and installed in a manner that accomplishes vector control.
- See PDF for table PDF
Note: To convert to cubic feet per second (cfs) divide gpm by 448.8.
- See PDF for table PDF
Note: To convert to cubic feet per second (cfs) divide gpm by 448.8.
- See PDF for table PDF
a. Sizing per manufacturer’s specifications.
Note: To convert to cubic feet per second (cfs) divide gpm by 448.8.
- See PDF for table PDF
Note: To convert to cubic feet per second (cfs) divide gpm by 448.8.
- See PDF for table PDF
(7) Other design requirements.
(a) Subsoil drains.
1. A subsoil drain discharging to a plumbing system shall discharge into an area drain, manhole or storm sewer, trapped receptor or a sump with a pump.
2. Where a foundation drain is subject to backwater, the drain shall be protected by a backwater valve or a sump with a pump.
(b) Backwater valve. All backwater valves shall be accessible for maintenance.
(c) Sewer location.
1. No storm building sewer or private interceptor main storm sewer may pass through or under a building to serve another building, unless one of the following conditions is met:
a. The storm building sewer or private interceptor main storm sewer serves farm buildings or farm houses, or both, that are located on one property.
b. Where a storm building sewer or private interceptor main storm sewer serves buildings that are located on one property, a document that indicates the piping and distribution arrangement for the property and buildings is recorded with the register of deeds no later than 90 days after installation.
2. The location of storm building drains and building sewers shall comply with ss. SPS 382.30 (11) (d) and 382.40 (8) (b) 7.
(d) Installation requirements.
1. The connection of a stormwater leader discharging to a storm building sewer shall be made at or above the finished grade.
Note: For more information regarding joints and connections, refer to s. SPS 384.40.
1m. If in direct connection and at finished grade, a removable strainer shall protect the inlet. The capacity of the strainer shall be provided in accordance with sub. (9) (b).
2. The elevation of a storm building drain shall comply with s. SPS 382.30 (11) (b) 1.
3. Interior inlets and drains subject to backflow or backwater shall be protected with a check valve or backwater valve.
4. Storm building drains and building sewers shall be installed to comply with s. SPS 382.30 (11) (e).
5. Storm building sewer connections to public sewers shall be in accordance with s. SPS 382.30 (11) (f).
6. Cleanouts for conveyance system piping shall be installed in accordance with s. SPS 382.35.
7. Storm building sewers that receive clearwater and that may be subject to freezing shall be installed in accordance with s. SPS 382.30 (11) (c) 2.
8. Storm building drains, clearwater building drains, and building storm sewers and appurtenances shall be separated from water wells by the applicable separation distances contained in chs. NR 811 and 812, or as otherwise permitted by the department of natural resources.
9. All underground stormwater storage tanks for water reuse shall be separated from sanitary sewers by a minimum of 8 feet.
10.
a. A means to locate buried non-metallic storm building sewers and private interceptor main sewers that discharge to municipal mains shall be provided in accordance with the options under s. SPS 382.30 (11) (h), except as provided in subd. 10. b.
b. Tracer wire insulation color for non-metallic storm pipe shall be brown.
11. Subsoil drain connections to the storm sewer shall be installed at a point above the horizontal center line of the storm sewer in such a manner that the subsoil drain is entirely above the top of the building sewer; or be provided with a backwater valve.
(e) Hydrodynamic stormwater separators. Hydrodynamic stormwater separators shall conform to ASTM F1745/F1745m.
(8) Sumps and pumps.
(a) Sumps.
1. ‘General.’ All storm building subdrains shall discharge into a sump, the contents of which shall be automatically lifted and discharged, dispersed or used in accordance with sub. (4).
2. ‘Construction and installation.’
a. Except as provided in subd. 2. c. and d., an interior sump shall have a rim extending at least one inch above the floor immediately adjacent to the sump.
b. A sump shall have a removable cover of sufficient strength for anticipated loads.
c. Where a sump is installed in an exterior meter pit or elevator pit, the rim may be level with the floor.
d. When a sump is provided with an airtight, solid cover.
3. ‘Location.’ All sumps installed for the purpose of receiving clearwater, groundwater or stormwater shall be separated from water wells by the applicable separation distances contained in chs. NR 811 and 812, or as otherwise permitted by the department of natural resources.
Note: See ch. SPS 382 Appendix A-382.30 (11) (d) for material reprinted from s. NR 812.08.
4. ‘Size.’
a. Except as permitted under subd. 4. b. or c. the size of each sump shall be no smaller than 16 inches in diameter at the top, 14 inches in diameter at the bottom, and 22 inches in depth, but in no case smaller than the manufacturer requirements to ensure sufficient pump run time.
b. The minimum sump diameter may be smaller than 16 inches when specified by the manufacturer for a combination sump and pump.
c. A sump located in an elevator pit may have a width or diameter of not less than 12 inches and a depth of not less than 12 inches.
5. ‘Solid covered sumps.’ A storm or clearwater sump with a solid cover shall be vented. The vent shall terminate a minimum of 1 inch above finished floor and be sized per Table 382.31-4. In lieu of a separate vent, a sealed sump may incorporate a radon vent connected to the subsoil drain or sump cover.
(b) Pumps.
1. ‘Size.’ The pump shall be of a capacity appropriate for the anticipated use.
2. ‘Discharge piping.’
a. Where a pump discharges into a storm drain system, a check valve shall be installed.
b. The minimum diameter discharge piping shall be based on the design flow rate of the pump and a minimum velocity of one foot/second.
3. ‘Clearwater discharge.’ Clearwater may not discharge into a stormwater sump, except for one- and 2-family dwellings.
(9) Inlet requirements.
Loading...
Loading...
Published under s. 35.93, Stats. Updated on the first day of each month. Entire code is always current. The Register date on each page is the date the chapter was last published.