Wis. Admin. Code SPS § SPS 382.30

Current through December 30, 2024

Section SPS 382.30 - Sanitary drain systems

(1) SCOPE. The provisions of this section set forth the requirements for the design and installation of sanitary drain systems, including building drains and building sewers.

Note: The provisions for storm and clear water drain systems are specified in s. SPS 382.36.

(2) MATERIALS. All sanitary drain systems shall be constructed of approved materials in accordance with ch. SPS 384.

(3) LOAD ON DRAIN PIPING.

(a)Intermittent flow.

1. 'Fixture.' The load factor on drain piping shall be computed in terms of drainage fixture unit values specified in Table 382.30-1 for the corresponding listed fixture.

2. 'Devices.' Drainage fixture unit values for intermittent flow devices not listed in Table 382.30-1 shall be computed on the basis of one fixture unit equalling one gallon per minute of flow.

Note: Equipment with a timed discharge cycle(s) of 2 minutes or less may be considered as an intermittent flow device.

(b)Continuous flow devices. Drainage fixtures unit values for continuous flow devices such as pumps, ejectors, air conditioning equipment or similar devices that discharge continuously shall be computed on the basis of 2 fixture units for each one gallon per minute of flow.

(4) SIZE OF DRAIN PIPING.

(a)Maximum loading.

1. The total drainage load in any portion of drain piping may not exceed the limits specified in Tables 382.30-2 and 382.30-3, but may be less than the limits specified in Tables 382.30-2 and 382.30-3 based on an approved alternate standard consistent with s. SPS 381.20 (2) or an analysis provided by a Wisconsin registered architect, registered professional engineer, or permitted designer of engineering systems - plumbing.

2. The drainage fixture unit values assigned to a receptor may be less than the limits specified in Tables 382.30-2 and 382.30-3 based on an approved alternate standard consistent with s. SPS 381.20 (2) or an analysis provided by a Wisconsin registered architect, registered professional engineer, or permitted designer of engineering systems - plumbing.

Note: See s. SPS 382.31 (17) for sizing requirements of combination drain and vent systems.

Note: See ch. SPS 382 Appendix for further explanatory material.

(b)Minimum size of building sewers.

1. 'Gravity flow sewers.' The minimum size of a gravity flow sanitary building sewer shall be 46 in diameter. A municipality or sanitary district by ordinance may require that portion of the building sewer between the lot line and the public sewer to be larger than 4 " in diameter.

2. 'Pressurized sewers.'

a. Sewers pressurized through the use of sewage ejectors, sewage pumps or sewage grinder pumps shall be sized to maintain a minimum flow velocity of 2 feet per second and shall be in accordance with the ejector or pump manufacturer's recommendations.

b. Pressurized building sewers shall be sized not less than 2" in diameter for sewage ejectors and sewage pumps, and 11/4 " in diameter for all sewage grinder pumps.

(c)Minimum size of private interceptor main sewers.

1. Except as provided in subd. 3., the minimum size of a gravity flow private interceptor main sewer shall be 4" in diameter.

2. Except as provided in subd. 3., the minimum size of pressurized private interceptor main sewer shall be such so as to maintain a minimum flow velocity of 2 feet per second.

3. A municipality or a sanitary district may by ordinance, require the minimum size of a private interceptor main sewer to be larger than 4" in diameter.

4. Private interceptor main sewers 6" or less in diameter may not exceed the drainage fixture limits in Table 382.30-3.

5. Private interceptor main sewers 8 " or larger in diameter shall conform with the design criteria specified in s. NR 110.13.

Note: See ch. SPS 382 Appendix A-382.30 (4) for further explanatory material.

(d)Future fixtures. Where provisions are made for the future installation of fixtures, the drainage fixture unit values of such fixtures shall be considered in determining the required sizes of drain and vent pipes. Construction to provide for future installations shall be terminated with a plugged fitting or fittings.

Table 382.30-1

Drainage Fixture Unit Values By Fixture Type

Type of Fixture^a	Drainage- Fixture UnitValue (dfu)	Trap Size Minimum Diameter (inches)
Automatic Clothes Washers:
Commercial type, individual .........	4	2
Commercial type, large capacity ......	a	a
Residential type ...................	4	2
Autopsy Table .......................	h	h
Bathroom Group, includes: water closet, lavatory, bathtub or shower ...........	6
Bathtubs, all types^b ...................	2	11/2
Bedpan Washer ......................	6	2
Beer Tap ............................	1/2	11/4
Bidet ...............................	2	11/2
Bottle Cooler ........................	1/2	11/4
Campsite Receptor ....................	6	4
Coffee Maker ........................	1/2	11/4
Cuspidor, fountain or dental .............	1	11/4
Dipper Well .........................	1	11/4
Dishwasher, commercial type ...........	c	c
Dishwasher, residential type ............	2	11/2
Drinking Fountain ....................	1/2	11/4
Elevator Threshold Drain ...............	a	4
Exhaust Hood Washer .................	4	2
Floor Drain:
2 inch ...........................	2	2
3 inch ...........................	3	3
4 inch ...........................	4	4
Larger than 4 inch ..................	4	d
Glass Filler ..........................	1/2	11/4
Glass Washer ........................	2	11/2
Health Care Fixtures:
Clinic sink ........................	6	NA
Exam/treatment sink ................	1	11/4
Sitz bath .........................	2	11/2
Ice Chest ...........................	1/2	11/2
Laundry Tray, 1 or 2 compartment .......	2	11/2
Lavatory ............................	1	11/4
Lavatory, combination per trap .........	1	11/2
Manufactured Home ..................	11	NA
Refrigerated Food Display Case .........	1	1
Shower Stall:
Residential .......................	2	2
Public, individual ..................	2	2
Public, group ......................	2 per shower head	2
Sinks:ⁱ
Bar, residential ....................	1	11/4
Breakroom (single compartment) ......	1	11/2
Cup .............................	1/2	11/4
Factory, wash, per set of faucets .......	1	11/2
Fountain wash up ..................	1	11/2
Fountain or Bar, 4 compartments or less	3	11/2
Food Waste Grinder, commercial 2 HP or less ...........................	2	f
Food Waste Grinder, commercial 3 HP or more ..........................	3	f
Laboratory ........................	2	11/2
Laboratory, school .................	2	11/2
Classroom ........................	1	11/4
Pack or plaster .....................	3	2
Residential, with or without food waste grinder ..........................	2	11/2
Restaurant, Scullery, pots and pans - 4 compartments or less ...............	3	f
Food, rinsing, cleaning or thawing .....	3	2
Service Sink, Flushing Rim ..........	6	3
Service Sink, 2 inch diameter, wall outlet	2	2
Service Sink, 3 inch diameter, wall outlet	3	3
Service Sink, 2 inch diameter, floor outlet	2	2
Service Sink, 3 inch diameter, floor outlet	3	3
Shampoo Sink, barber or beauty parlor.	2	11/2
Surgeons, wash up .................	3	11/2
Wash Fountain, circular and semi-circular	2	11/2
Receptors of Indirect Wastes, gravity flow discharge:
11/4 inch receptor outlet diameter ......	1	11/4
11/2 inch receptor outlet diameter ......	2	11/2
2 inch receptor outlet diameter ........	3	2
3 inch receptor outlet diameter ........	4	3
4 inch receptor outlet diameter ........	6	4
Larger than 4 inch receptor outlet diameter .........................	8	f
Soda Dispenser ......................	1/2	11/4
Sterilizers:
Bedpan ..........................	4	2
Garbage can washer ................	3	3
Instrument or water .................	1
Urinal ..............................	2	g
Water Closet, nonpublic ................	4	g
Water Closet, public ...................	6	g
NA = not applicable

^a Based on discharge rate of the fixture.

^b Includes foot, sitz and infant baths and regular bathtubs with or without showers or whirlpool circulation piping.

^c Based on discharge rates and number of outlets; a 4" diameter trap and drain pipe minimum recommended.

^d Trap size corresponds to the size of the floor drain.

^f Trap size corresponds to the size of the drain outlet.

^g Trap size specified in referenced standards of s. SPS 384.20.

^h Trap size corresponds to the size of the drain outlet. Use the dfu value of the receptor serving the autopsy table.

ⁱ Sinks not specified in this table shall be assigned 1 dfu for 11/4" tailpiece, 2 dfu for 11/2" tailpiece and 3 dfu for 2" tailpiece.

Table 382.30-2

Stacks And Drain Piping

Pipe Diameter (inches)	Maximum Number of Drainage Fixture Units That May Drain Through Any Portion of Drain Piping^a
	Drain Piping Other Than Stacks^b	Stacks^c
	Drain Piping Other Than Stacks^b	Total Discharge from Side Connections into One Branch Interval^d,e	Stacks of 3 Branch Intervals or Less	Stacks of More Than 3 Branch Intervals
1 1/4	1	1	2	2
1 1/2	3	2	4	8
2	6	6	10	24
3	20	20	48	72
4	160	90	240	500
5	360	200	540	1,100
6	620	350	960	1,900
8	1,400	600	2,200	3,600
10	2,500	1,000	3,800	5,600
12	3,900	1,500	6,000	8,400
15	7,000	f	f	f

^a Through any portion of a stack includes all of the flow at the design point.

^b Does not include building drains and subdrains, building sewers, private interceptor main sewers and forced discharge piping.

^c Drain stacks may be reduced in size as the drainage load decreases to a minimum diameter of one half of the diameter required at the base of the stack, but not smaller than that required for a stack vent under s. SPS 382.31 (14) (a).

^d Into one branch interval includes the discharge from the top fitting of the branch interval and does not include the discharge from the bottom most fitting creating the branch interval.

^e Reduction in diameter may occur within a branch interval.

^f Sizing based on design criteria.

Table 382.30-3

Building Drains, Building Subdrains, Building Sewers and Private Inter ceptor Main Sewers^a

Pipe Diameter (inches)	Maximum Number of Drainage Fixture Units Which May Drain Through Any Portion of a Building Drain, Building Subdrain, Building Sewer or Private Interceptor Main Sewer
	Pitch (inch per foot)
	1/16	1/8	1/4	1/2
1 1/4	NP^b	NP	1	1
1 1/2	NP	NP	3	3
2	NP	NP	6	9
3	NP	36	42	50
4	NP	180	216	250
5	NP	390	480	575
6	NP	700	840	1,000
8	1,400	1,600	1,920	2,300
10	2,500	2,900	3,500	4,200
12	3,900	4,600	5,600	6,700
15	7,000	8,300	10,000	12,000

^a Private interceptor main sewers 6 inches or less in diameter, see s. NR 1 10.13 for private interceptor main sewers 8 inches or larger in diameter.

^b NP means Not Permitted.

Note: For further explanatory material see ch. SPS 382 Appendix A-382.30 (4).

(5) PITCH OF HORIZONTAL DRAIN PIPING. All horizontal drain piping 4" or larger in diameter shall be installed at a pitch which produces a computed velocity of at least 2 feet per second when flowing half full.

(a)Horizontal branch drains.

1. The minimum pitch of horizontal branch drains 2" or less in diameter shall be 1/ 4" per foot.

2. The minimum pitch of horizontal branch drains larger than 26 in diameter shall be 1/ 8" per foot.

(b)Building drains and building sewers.

1. The minimum pitch of building drains shall be in accordance with Table 382.30-3.

a. The minimum pitch of building sewers 10" or less in diameter shall be in accordance with Table 382.30-3.

b. The minimum pitch of building sewers 12" or larger in diameter shall conform with the minimum pitch specified for municipal sewers in s. NR 110.13.

Note: See also s. SPS 382.30 (4) (c) 5. for further explanatory material.

(c)Private interceptor main sewers.

1. The minimum pitch of private interceptor main sewers 6" or less in diameter shall be in accordance with Table 382.30-3.

2. The minimum pitch of private interceptor main sewers 8" or larger in diameter shall conform with the minimum pitch specified for municipal sewers in s. NR 110.13.

Note: See ch. SPS 382 Appendix for further explanatory material.

(6) OFFSETS IN VERTICAL DRAINS. Offsets in vertical drain piping shall be in accordance with this subsection.

(a)Offsets of 45° or less.

1. An offset in a vertical drain, with a change in direction of 45° or less from the vertical, shall be sized as a vertical drain piping in accordance with sub. (4).

2. Except as provided in par. (c), where a horizontal branch connects to a drain stack within 2 feet above or below an offset with a change of direction of 30° to 45° from the vertical and the offset is located 5 or more branch intervals below the top of the stack, the offset shall be vented in accordance with s. SPS 382.31 (5) (a).

(b)Offsets of more than 45°. Except as provided in par. (c), a drain stack with an offset of more than 45° from the vertical shall be installed in accordance with subds. 1. to 5.

1. That portion of the drain stack above the highest offset shall be sized as for vertical drain piping in accordance with sub. (4).

2. That portion of the offset between and including the offset fittings shall be sized as building drain piping in accordance with sub. (4).

3. That portion of stack below the offset shall be not less than the size of the offset.

4. Where an offset of more than 45 o is located more than four branch intervals below the top of the drain stack, a horizontal branch may not connect within the offset or within 2 feet above or below such offset.

a. Except as exempted in subd. 5. b., or par. (c), where an offset in a drain stack with a change of more than 45° from vertical is located below 5 or more branch intervals, the offset shall be vented in accordance with s. SPS 382.31 (5) (b).

b. The vent required in subd. 5. a. shall not be required where the drain stack, including the offset, is sized one pipe size larger than required for a building drain designed to serve as per sub. (4) and the entire stack and offset are not less in cross sectional area than that required for a stack plus the area of a vent as required in s. SPS 382.31 (5) (b).

Note: See ch. SPS 382 Appendix for further explanatory material.

(c)Exception. Where an offset is located two or more feet below the lowest branch drain connection to the stack, the venting specified in this subsection and s. SPS 382.31 (5) (b) is not required.

(7) HORIZONTAL BRANCH DRAIN CONNECTION AT BASE OF A STACK.

(a) A horizontal branch drain may not connect downstream from the base fitting of a drain stack 2" or larger in diameter within the distance equal to 10 pipe diameters of the drain to which the horizontal branch drain connects.

(b) A building drain branch or building subdrain branch may not connect to a building drain or building subdrain downstream from the base fitting of a drain stack 2" or larger in diameter within the distance equal to 20 pipe diameters of the building drain or building subdrain.

Note: See ch. SPS 382 Appendix for further explanatory material.

(8) PIPING CHANGES IN DIRECTION. Changes in the direction of drain piping shall be accomplished in accordance with the requirements of this subsection.

(a)Fittings. All changes in direction of flow in drain piping shall be made by the appropriate use of 45 degree wyes, long or short sweep quarter bends, sixth, eighth, or sixteenth bends, or by a combination of these or other equivalent fittings. Except as provided in subds. 1. to 3., fittings which change the direction of flow for drain piping 86 or less in diameter shall conform to the minimum radii specified in Table 382.30-4.

Note: See ch. SPS 382 Appendix for further explanatory material.

1. The minimum radius for the first 90° fitting downstream from a trap serving a lavatory or sink shall be 1-3/4" for drain piping 1-1/2" in diameter. The fitting shall be a tee or quarter bend.

2. The minimum radius for the first 90° bend or elbow downstream from a water closet shall be 2-1/2" for drain piping 3" in diameter.

3. The minimum radius for the first 90° bend or elbow downstream from a water closet shall be 3 " for drain piping 4 " in diameter.

Table 382.30-4

Minimum Radii of Fittings (in inches)

Diameter of pipe (inches)	Changes in Direction of Flow
Diameter of pipe (inches)	Horizontal to Vertical	Vertical to Horizontal and Horizontal to Horizontal
1-1/4	1-1/8	2-1/4
1-1/2	1-3/8	2-3/4
2	1-7/8	3-1/4
3	2-7/8	4-1/16
4	3-3/4	4-7/8
5	4-1/2	6-1/2
6	5	7
8	6	8

(b)Blowout type fixtures. Where blowout type fixtures are installed back to back, appropriate fittings shall be installed to prevent the passage of wastes from one fixture to the other.

(9) DRAIN FITTINGS AND CONNECTIONS. Drain fittings, connections, devices and methods of installation shall not obstruct or retard the flow of water, wastes, sewage or air in the drain system or venting system in an amount greater than the normal frictional resistance to flow, unless as otherwise permitted in this chapter or unless approved by the department.

(a)Closet bend. The reduction of a 4 x 3 inch closet bend or collar fitting from 4" to 3" shall not be considered an obstruction.

(b)Side inlet tees or bends. The side inlet of a low pattern or high pattern tee or bend shall not be used as a vent connection when the side inlet is placed in a horizontal position or when any arrangement of piping or fittings produces a similar effect.

(c)Prohibited fittings and connections. The types of fittings and connections specified in subds. 1. to 4. shall not be used for drain piping:

1. A heel inlet bend when the heel inlet is in the horizontal position;

2. A fitting or connection which has an enlargement chamber or recess with a ledge or shoulder, or reduction in pipe area in the direction of flow;

3. A fitting which has running threads; and

4. A connection by means of drilling and tapping of a drain or vent pipe, unless as otherwise approved by the department.

(d)Saddles. If a pipe saddle is used to connect drain piping together, the saddle shall be installed in accordance with s. SPS 384.30 (5) (d).

(10) SUMPS, EJECTORS AND PUMPS.

(a)Sumps.

1. 'General.' All sanitary building subdrains shall discharge into an approved, vented sump with an airtight cover. The sump shall be so located as to receive the wastewater by gravity flow, and shall be located at least 25 feet from any water well or as otherwise approved by the department of natural resources.

2. 'Capacity.' Except as provided in pars. (c) and (d), the minimum capacity of the sump shall be determined in accordance with the provisions of subd. 2. a. to e. Capacity shall be based on one pump only.

a. The water supply fixture unit method shall be used to determine peak input flow in gallons per minute; only the fixtures that drain to the sump shall be included.

Note: When converting water fixture units to gallons per minute it is permissible to calculate the load as a supply system with predominantly flush tanks.

b. The capacity of the sump shall be such that the pump when actuated by the lowest "pump on" switch runs at least 20 seconds.

c. Between the highest "pump on" switch level and the sump inlet, the sump shall hold the amount of input that exceeds the discharge of the pumping equipment in a 5 minute peak input period. In no case shall the vertical distance between the switch and the inlet be less than 3 inches.

d. The low water level shall be maintained in accordance with the pump manufacturer's requirements, but shall not be less than 46 above the sump bottom.

e. Sumps containing one pump shall have an inside diameter of at least 24". Sumps containing 2 pumps shall have an inside diameter of at least 306.

Note: See ch. SPS 382 Appendix for further explanatory material.

3. 'Vents.' All sumps and all drains leading to a sump shall be vented in accordance with s. SPS 382.31.

4. 'Materials.' All sumps shall be constructed in a watertight manner of approved materials in accordance with ch. SPS 384.

5. 'Removable covers.' Penetrations through the top of removable sump covers shall be limited to those for the electrical supply, the vent piping and the discharge piping for the pump or pumps.

(b)Ejectors and pumps.

1. 'Where required.' The liquid from all sanitary building sumps shall be lifted and discharged into the building sanitary drain system by automatic ejectors, pumps or any other equally efficient method approved by the department.

2. 'Duplex equipment.'

a. Duplex ejector or pumping equipment shall be installed in a public building where 3 or more water closets or more than 20 drainage fixture units discharge into a sump.

b. Duplex ejector or pumping equipment shall be installed where the sanitary wastes of 2 or more one- or 2-family dwellings discharge into a sump.

c. Where duplex ejector or pumping equipment is installed, appropriate devices shall be installed to automatically alternate operation of the pumps or ejectors and to operate both pumps or ejectors when one unit cannot handle the load.

d. Where duplex pumping equipment is installed, an audible or visual alarm system with a manual control reset shall be installed to indicate pump failure.

3. 'Size.' The size and design of an ejector or pump shall be determined by the capacity of the sump to be served, the discharge head and discharge frequency. All ejectors and pumps shall provide a minimum flow velocity of 2 feet per second in the forced discharge piping.

Note: See ch. SPS 382 Appendix for velocity in relation to flow rate by various pipe sizes.

Note: Ejectors or pumps discharging to septic tanks may disturb the normal settling properties of the tank environment; contact the Division of Industry Services for more information.

a. All sewage grinder pumps shall have a minimum 1 1/ 4" diameter discharge opening and discharge piping.

b. All nongrinder-type sewage pumps serving water closets shall be capable of passing a 2" diameter solid ball and shall have a minimum 26 diameter discharge opening and discharge piping. All other pumps handling sanitary wastes shall be rated by the manufacturer as an effluent pump, shall be capable of passing a 1/ 2" diameter solid ball and shall have a minimum 1 1/ 4" diameter discharge opening and discharge piping.

4. 'Discharge connections.'

a. The discharge pipe from the ejector or pump shall be connected to the gravity drain by means of a wye pattern fitting. Where the fitting connects to a horizontal drain, the bottom of the wye branch of the fitting shall be located above the horizontal center line.

b. With the exception of exterior sumps, a full flow check valve shall be installed in the discharge piping from each ejector or pump.

c. Where duplicate ejector or pumping equipment is installed, each discharge pipe from an ejector or pump shall be provided with a gate or ball type valve installed downstream of each full flow check valve.

5. 'Discharge pipe air relief.' Air relief valves shall be provided at all high points in the discharge piping of an ejector or pump where the piping arrangement creates an air trap.

6. 'Prohibited connections.' No fixtures may be connected to the discharge pipe between the ejector or pump and the point where it enters the gravity drain.

7. 'Maintenance.' All ejectors, pumps and like appliances shall receive care as needed to keep them in a satisfactory operating condition.

(c)Prefabricated pump and sump systems. Macerating toilet systems and waste pumping systems for plumbing fixtures shall conform to ASME A112.3.4-2018/CSA B45.9-18. If unspecified by the manufacturer, the minimum capacity of a pump and sump system shall be determined in accordance with all of the following:

1. The water supply fixture unit, wsfu, method shall be used to determine peak input flow in gallons per minute. The peak input shall include all the fixtures that drain to the sump.

2. Unless storage is provided as specified in par. (a) 2., the capacity of the prefabricated pump and sump system shall accommodate the peak input flow.

3. The low water level shall be maintained in accordance with the pump manufacturer's requirements.

(d)Exterior sumps. Exterior sumps shall comply with s. SPS 384.25. The minimum capacity of exterior sumps shall be determined in accordance with all of the following:

1. Peak input flow in gallons per minute shall be determined in accordance with either of the following:

a. The water supply fixture unit, wsfu, method of all the fixtures that drain to the sump.

b. The provisions as specified in s. SPS 383.43 (2) through (6).

2. In lieu of providing the duplex pumping equipment as specified in par. (b) 2., a one-day holding capacity may be provided above a high level alarm when installed on a simplex system.

(11) BUILDING DRAINS AND BUILDING SEWERS.

(a)Limitations. No building sewer may pass through or under a building to serve another building, unless:

1. The building sewer serves farm buildings or farm houses, or both, which are all located on one property; or

2. The building sewer or private interceptor main sewer serves buildings located on the same property and a document, which indicates the piping and distribution arrangement for the property and buildings, shall be recorded with the register of deeds no later than 90 days after installation.

(b)Building drains.

1. 'Elevation.'

a. All building drains shall be installed below the lowest floor levels on which fixtures may be installed if the public sewer, POWTs or private interceptor main sewer elevation permits.

b. Where any portion of an above-ground building drain discharges to a vertical pipe, the building drain shall connect to the building sewer at an elevation at least 30" above the basement floor.

Note: See ch. SPS 382 Appendix for further explanatory material.

2. 'Backwater protection.' A building drain subject to backflow or backwater shall be protected with a backwater valve or with a sump with pumping equipment in accordance with sub. (10).

a. Backwater valves, when fully open, shall have a capacity not less than that of the pipes in which installed.

b. Backwater valves shall be so located as to be readily accessible for cleaning.

3. 'Floor drain required.'

a. Where a plumbing fixture or appliance is located on a floor which is entirely below grade, a floor drain shall be installed to serve that floor.

b. In any room containing the recessed or concealed portions of sterilizers located in health care or related facilities, at least one floor drain connecting to the drainage system shall be installed in a manner to adequately drain the entire floor area.

Note: See the pool code, s. SPS 390.19 (2) for drain requirements for swimming pool toilet or locker rooms. "SPS 390.19 (2) DRAINAGE OF COVERED AREAS.

(a) Floor drains shall be installed in toilet rooms and locker rooms where sanitary fixtures are located and where the room door is adjacent to the deck or adjacent to the impervious walkway draining to the deck.

(b) Floor drain openings shall be 1/4 inch or less in width or diameter.

(c) Floors shall be pitched to drain."

(c)Building sewers.

1. 'Minimum depth.'

a. The top of a building sewer shall be located at a depth of not less than 426 below finished grade, except as provided in subd. 1. b. or subd. 2.

b. The top of a building sewer which discharges to a septic tank, holding tank or grease interceptor shall be located at a depth of not less than 18" below finished grade.

2. 'Protection from frost.'

a. Except as provided in subd. 2. c. to e., a building sewer or private interceptor main sewer shall be protected from frost in accordance with subd. 3. in areas where the top of the building sewer or private interceptor main sewer is located less than 60" below a surface area from which snow will be cleared.

b. Except as provided in subd. 2. c. to e., a building sewer or private interceptor main sewer shall be protected from frost in accordance with subd. 3. in areas where the top of the building sewer or private interceptor main sewer is located less than 42" below a surface area which snow will not be cleared.

c. Where a building sewer or private interceptor main sewer discharges to a holding tank, POWTs treatment tank or grease interceptor, the portion of a building sewer or private interceptor main sewer which is within 30 feet from the connecting building drain and which is under a surface area from which snow will not be cleared shall not be required to be protected from frost.

d. Frost protection for a building sewer shall not be required where the predicted depth of frost as determined from Figure 382.30-1 and Table 382.30-6 does not extend below the top of the building sewer.

e. Where a building sewer or private interceptor main sewer is installed to serve public facilities that are not open during the period from November 15 to March 15 and which are not places of employment, frost protection requirements shall not apply.

Note: This exemption applies to frost sleeves as provided in s. SPS 382.35 (5) (a) 2.

3. 'Insulation for building sewers.' Where required by subd. 2. a. or b., building sewer or private interceptor main sewer insulation for frost protection shall be provided in accordance with one of the methods specified in subd. 3. a. to d.

a. Extruded polystyrene foam insulation shall be installed at a depth of at least 18" below finished grade and at least 6" above the top of the sewer pipe. The minimum thickness and width of the foam insulation shall be determined from Figure 382.30-1 and Tables 382.30-5 to 382.30-7. If the insulation is to be installed more than 6" above the top of the sewer, the number of inches exceeding 6" shall be added to the width of insulation determined from Table 382.30-7.

b. Extruded polystyrene foam insulation shall be installed using a box method. The 3-sided box shall be formed with 3 lengths of polystyrene foam insulation where the top of the box extends horizontally to the farthest edge of both vertical sides. The insulation shall be installed at or below a depth of at least 12" below finished grade and 6" above the top and 6" from each side of the building sewer or private interceptor main sewer. The minimum thickness of the foam insulation shall be determined from Figure 382.30-1 and Table 382.30-5.

Note: See ch. SPS 382 Appendix for further explanatory material.

c. Lightweight insulating concrete shall be installed to the depth of the spring line of the sewer and shall extend laterally at least 6" on both sides of the sewer. The minimum thickness of the insulating concrete shall be determined from Figure 382.30-1 and Table 382.30-5. The thickness shall be measured from the top of the sewer. The top of the insulation shall be installed at least 12" below finished grade.

d. Alternative methods of frost protection shall be approved by the department.

Figure 382.30 -1. Frost protection zones.

See Image

Table 382.30-5

Minimum Thickness of Insulation

Frost Protection Zone	Extruded Polystyrene Foam (in inches)	Insulating Concrete (in inches)
A	1.0	6
B	1.5	9
C	2.0	12
D	2.5	15

Table 382.30-6

Predicted Depth of Frost in Various Types of Backfill Soil (in feet)

Soil Type	Frost Protection Zone
Soil Type	A	B	C	D
Clay, Clay Loam	2.5	3.0	3.5	4.0
Silt Loam, Silty Clay Loam	3.5	4.0	4.5	5.5
Sandy Clay Loam	4.0	4.5	5.5	6.0
Sandy Loam, Loamy Sand	4.5	5.0	6.0	6.5
Sand	5.0	5.5	6.5	7.5
Gravelly Sand	6.0	7.5	9.0	10.0

Table 382.30-7

Minimum Width of Extruded Polystyrene Foam Insulation (in feet)

Predicted Depth of Frost (feet)	Depth of Sewer (in feet)
Predicted Depth of Frost (feet)	2.0	2.5	3.0	3.5	4.0	4.5
2.5	2	NR
3.0	3	2	NR
3.5	4	3	2	NR
4.0	5	4	3	2	NR
4.5	6	5	4	3	2	NR
5.0	7	6	5	4	3	2
5.5	8	7	6	5	4	3
6.0	9	8	7	6	5	4
6.5	10	9	8	7	6	5
7.0	10	10	9	8	7	6
7.5	10	10	10	9	8	7
8.0	10	10	10	10	9	8
8.5	10	10	10	10	10	9
9.0	10	10	10	10	10	10
10.0	10	10	10	10	10	10

NR means Not Required.

(d)Location limitations. Building drains, building sewers or private interceptor main sewers shall be separated from water wells by the applicable separation distances contained in chs. NR 811 and 812 or as otherwise approved by the department of natural resources.

Note: See s. SPS 382.40 for provisions regarding the separation of water supply piping, building sewers and private interceptor main sewers.

Note: See ch. SPS 382 Appendix for further explanatory material. Section NR 812.08 may require additional setbacks.

(e)Installation of building drains and building sewers.

1. 'Trenching.' All excavations for building drains and building sewers shall be open trench work, unless otherwise permitted by local ordinance or accepted by the local inspector.

2. 'Stable bottom.' Where the bottom of the trench can be maintained in a stable condition and free of water during the time of installation the building drain and the building sewer shall be bedded and initially backfilled to comply with all the following requirements:

a. Where the trench bottom does not contain stone larger than one inch in size or where bedrock is not encountered, the trench may be excavated to grade.

b. Where stone larger than one inch size or when bedrock is encountered, the trench shall be excavated to a depth at least 3 inches below the grade elevation and shall be brought back to grade with a bedding of sand, gravel or crushed stone that shall be of a size that all the material shall pass a 3/4-inch sieve.

c. Bedding shall be sufficiently dry and hand or mechanically compacted to a minimum of 90 percent standard proctor density.

d. Initial backfill to a depth of 12 inches over the pipe shall be sand, crushed stone or excavated material which is neither corrosive nor organic in nature.

e. Initial backfill shall be of a size that passes a one-inch sieve.

f. A concrete floor may be placed over a building drain having less than 12 inches of initial backfill.

g. Initial backfill shall be placed in increments not to exceed 6 inches in depth.

h. Initial backfill shall be well tamped for the full width of the trench and length of the sewer.

3. 'Unstable bottom.' Where a mucky or unstable bottom is encountered in the trench, the required dry and stable foundation conditions shall be provided by providing one of the following options:

a. Sheathing shall be driven and left in place to a depth of 48 inches below the trench bottom or to solid foundation to a lesser depth.

b. Removal of wet and yielding material to a depth of 24 inches or to solid material and replacement of the unstable material with limestone screenings, pea gravel or equivalent material.

c. Install a longitudinally reinforced concrete cradle the width of the trench and at least 3 inches thick.

d. Install a longitudinally reinforced concrete slab the width of the trench and at least 3 inches thick.

e. Backfill and bedding shall comply with subd. 2. d. to h.

4. 'Backfill completion.' Care shall be exercised in placing the balance of the backfill to prevent breakage of the pipe. Large boulders or rock, concrete slabs, or frozen masses shall not be used in the backfill. At least 366 of backfill cover shall be provided over the top of the pipe before the pipe trench is wheel-loaded.

5. 'Pipe openings protected.' The ends of all pipes not immediately connected shall be closed so as to prevent the introduction of earth or drainage from an excavation.

(f)Connection to public sewer. The connections of building sewers to public sewers shall be in accordance with conditions of approval for the public sewer granted by the department of natural resources under s. 281.41, Stats.

1. 'Gravity public sewer.' When a building sewer connection to the public sewer is not found within 3 feet of the point designated by the local governing body or its authorized representative, the connection shall be made in accordance with one of the provisions specified in subd. 1. a. to d.

a. A saddle fitting approved by the department and acceptable to the municipality or sanitary district shall be installed.

b. Where acceptable to the municipality or sanitary district a portion of the main sewer may be removed and a tee or wye fitting approved by the department may be inserted with compression joints in the public sewer acceptable to the municipality or the sanitary district. The insertion shall be made under the supervision of the authorized representative of the municipality or the sanitary district.

c. When the public sewer is concrete or clay, the end of the connecting sewer may be set upon or in an opening cut into the top half of the public sewer, but shall not protrude into the public sewer. The connection shall be secured by encasing the main sewer pipe and the connection in concrete at least 3" thick so as to assure permanency of the connection and adequate backing of the public sewer pipe.

d. In lieu of the use of a fitting and in the event that an opening cannot be located in the top half of the public sewer, a length of concrete or clay public sewer pipe may be removed and a section with a wye fitting shall be inserted in its place. The joints at the ends of the section shall be encased in concrete at least 3" thick. The connection or insertion shall be made under the supervision of the authorized representative of the municipality or the sanitary district.

2. 'Pressurized public sewer.' Where a forced building sewer discharges to a pressurized public sewer all of the following requirements shall apply:

a. A curb stop shall be installed on the same property as close as possible to the connection to the common forced main sewer.

b. A check valve shall be installed in the pressurized building drain or building sewer.

c. An accessible quick disconnect shall be installed upstream of the check valve.

Note: See ch. SPS 382 Appendix for further explanatory material.

(g)Prohibited installations.

1. 'Harmful discharge.' No person may connect to a public sewer any building drain or building sewer through which is discharged any substance likely to cause undue corrosion, obstruction, nuisance, explosion or interference with sewage treatment processes.

2. 'Storm water and clear water connections.' Except as provided in s. SPS 382.36 (3), storm drain piping and clear water drain piping may not discharge to a sanitary building drain which connects to a publicly-owned treatment works.

Note: See s. SPS 382.36 for provisions relative to storm sewers.

(h)Locating requirements. A means to locate buried non-metallic sewers and private interceptor main sewers discharging to municipal mains shall be accomplished in accordance with one of the following options:

Note: See ch. SPS 382 Appendix for further information.

1. A tracer wire shall be installed in accordance with all of the following:

a. Tracer wire shall be installed along the length of the non-metallic pipe.

b. Tracer wire shall be a minimum of 18 gauge, insulated, single-conductor copper wire or equivalent.

c. Tracer wire shall be located directly above and within 6 inches of the non-metallic pipe.

d. Tracer wire shall be accessible and locatable within the owner's property at 400-foot intervals or increments thereof.

e. Exterior access locations shall include a means of protecting the tracer wire.

f. In-ground sleeves shall be installed as provided in s. SPS 382.35 (5) (a) 2. c. and d.

g. Where tracer wire is more than 6 inches from the pipe, tracer wire insulation color shall comply with subd. 1. h.

h. Tracer wire insulation color for non-metallic sewer pipe shall be green.

i. Tracer wire conductivity shall be tested prior to use.

j. Conductive warning tape may not be utilized in lieu of tracer wire.

2. Global positioning system data shall be recorded with the municipality where the non-metallic pipe is installed.

3. Another equally-effective means acceptable to the department shall be employed to mark the location of the non-metallic pipe.

(12) PRIVATE INTERCEPTOR MAIN SEWERS.

(a) The connection of a private interceptor main sewer to a public sewer shall be in accordance with the conditions of approval for the public sewer granted by the department of natural resources under s. 281.41, Stats.

(b) Private interceptor main sewers which discharge to a municipal treatment facility shall be designed in accordance with the appropriate water quality management plan.

(c) All private interceptor main sewers shall be tested in accordance with s. SPS 382.21.

(d) Private interceptor main sewers 6" or less in diameter shall be installed in accordance with the criteria for building sewers specified in sub. (11) (b) and (c) and (d) and (e).

(e) Private interceptor main sewers 8" or larger in diameter shall be:

1. Provided with frost protection in accordance with sub. (11) (c); and

2. Installed in accordance with the municipal sewer criteria specified in s. NR 110.13.

(f) No private interceptor main sewer may pass through or under a building to serve another building, unless one of the following conditions are met:

1. The private interceptor main sewer serves farm buildings, farm houses, or both which are located on one property.

2. The private interceptor main sewer serves buildings that are located on one property and a document, which indicates the piping and distribution arrangement for the property and buildings, shall be recorded with the register of deeds no later than 90 days after installation.

3. An easement and agreement for maintenance and repairs shall be recorded with the register of deeds no later than 90 days after installation.

(13) LOCATION OF DRAIN PIPING.

(a) Drain piping located below the ceilings of areas where food, ice or potable liquids are prepared, handled, stored or displayed shall be installed with the least number of joints and shall be installed in accordance with subds. 1. to 5.

1. All pipe openings through floors shall be provided with sleeves bonded to the floor construction and protruding not less than one inch above the top of the finish floor with the space between sleeve and the piping sealed.

2. Plumbing fixtures, except bathtubs and showers, shall be of the wall mounted type. Bathtubs shall have waste and overflow connections made above the floor and piped to a trap below the floor.

3. Floor and shower drains installed shall be equipped with integral seepage pans.

4. Cleanouts for piping shall be extended through the floor construction above.

5. Piping subject to operation at temperatures that will form condensation on the exterior of the pipe shall be thermally insulated.

(b) Where drain piping is located in ceilings of areas where food, ice or potable liquids are prepared, handled stored or displayed, the ceilings shall be of the removable type, or shall be provided with access panels in order to provide an access for inspection of the piping.

(c) Exposed drain piping shall not be located over a pool, surge tank or an open filter for a pool except where a trough is installed below exposed drain piping to divert the flow of seepage to a discharge point consistent with Table 382.38-1.

Note: See ch. SPS 382 Appendix for examples of exposed piping considerations.

(14) VACUUM WASTE COLLECTION SYSTEMS.

(a) Vacuum waste collection systems shall do all of the following:

1. Conform to CSA b45.13:19/IAPMO z1700-2019.

2. Be designed and installed in accordance with the manufacturer's instructions.

3. Include a vacuum generating system, waste collection center, piping network, vacuum valve and control components used to isolate the vacuum piping network from atmospheric pressure and collect waste at the point of origin. If a vacuum system provides the only means of sanitation, then a contingency system set to operate automatically shall be installed.

(b) Vacuum generating systems shall do all of the following:

1. Include vacuum pumps adequate to create a constant vacuum in the piping network and storage tanks.

2. Have automated controls for the operating of pumps, collection tanks and alarms.

3. Include demand activated vacuum pumps.

4. Be provided with a vacuum pump exhaust vent capable of handling the total air volume of the vacuum pump.

(c) Waste collection centers or storage tanks shall do all of the following:

1. Be adequately sized to prevent fouling of the system.

2. Be designed to withstand 150% of the rated vacuum created by the vacuum generating system without leakage or collapse.

3. Be accessible for inspection, repair, and replacement.

(d) Vacuum piping networks shall do all of the following:

1. Be designed to withstand 150% of the rated vacuum created by the vacuum generating system without leakage or collapse.

2. Be under continuous vacuum.

3. Be constructed of materials specified by the manufacturer.

4. Be sized in accordance with the manufacturer's instructions.

5. Connect to water closets with at least 1 1/2 inch. i.d. piping.

(e) Vacuum interface valves shall do all of the following:

1. Be installed to isolate the vacuum piping network from atmospheric pressure.

2. Open automatically when a waste removal cycle is initiated for the fixture.

(f) Control components shall include levels indicator switches that automatically control the discharge pumps and provide all of the following warnings of malfunction or blockage:

1. Start discharge.

2. Stop discharge.

3. Audible alarm for abnormally high effluent levels.

4. Full tank shutdown warning.

(g) Gravity type fixtures shall conform to s. SPS 384.20.

(h) Vacuum water closets shall do all of the following:

1. Have s. SPS 382.41 listed vacuum breakers installed in fixture supply piping.

2. Have a WSFU value of 1.

(i) Piping hangers and supports used in vacuum waste collection systems shall conform to s. SPS 382.60.

Wis. Admin. Code Department of Safety and Professional Services § SPS 382.30

Cr. Register, February, 1985, No. 350, eff. 3-1-85; am. Table 82.30-1, (8) (a), (9) (c) (intro.) and 3., and (10) (b) 3. b., r. and recr. (4) (d) 2., Table 82.30-4, (10) (a) 2. b., (11) (intro.) and (f) 2., cr. (8) (a) 1. to 3. and (9) (d), r. (9) (c) 4., renum. (9) (c) 5. to be 4. and am., Register, May, 1988, No. 389, eff. 6-1-88; r. and recr. (4) (d), am. Table 82.30-3 and 82.30-7, r. (11) (intro.), renum. (11) (a) to (f) to be (b) to (g), cr. (11) (a) and (12) (f), Register, August, 1991, No. 428, eff. 9-1-91; am. Table 82.30-1, Register, April, 1992, No. 436, eff. 5-1-92; am. (7) (a) and (b), (11) (c) 1. a., (12) (e) 1. and Table 82.30-1, cr. (10) (a) 5., r. (11) (b) 1. b., renum. (11) (b) 1. c. to be (11) (b) 1. b., Register, February, 1994, No. 458, eff. 3-1-94; reprinted to restore dropped copy in (10) (b) 3. b., Register, July, 1994, No. 463; corrections in (11) (f) and (12) (g) made under s. 13.93(2m) (b) 7, Stats., Register, April, 1998, No. 508; am. (11) (g) 2., Register, April, 2000, No. 532, eff. 7-1-00; CR 02-002: am. (4) (d) 5., (5) (b) 2. b., (c) 2., (10) (a) 2., (b) 4. b., (11) (b) 1. a., (c) 2. a. to c., 3. (intro.), (g) 2., (12) (f) (intro.) and 1., and Tables 82.30 -1, 2, 3, 5 and 6, cr. (10) (b) 2. d., (c), (d), (11) (b) 3. b. and (c) 2. e., r. and recr. (11) (a) 2., (d), and (12) (f) 2., renum. (11) (b) 3., (c) 3. b. and c. to be (11) (b) 3. a., (c) 3. c. and d., Register April 2003 No. 568, eff. 5-1-03; CR 04-035: r. (3) (b) 32. a., am. Table 82.30-1 Register November 2004 No. 587, eff. 12-1-04; CR 07-069: cr. (11) (h) Register February 2008 No. 626, eff. 3-1-08; CR 08-055: am. (3), (6) (a) 2., (b) 1. to 3., (10) (a) 1., Tables 82.30 -1 and 82.30-3, r. (4) (b), renum. (4) (c) to (e) and (11) (h) 1. g. to i. to be (4) (b) to (d), and (11) (h) 1. h. to j., r. and recr. (6) (b) 4., 5., (11) (e) 2., 3., (f) 2. and Table 82.30-2, cr. (11) (h) 1. g. Register February 2009 No. 638, eff. 3-1-09; correction in (6) (a) made under s. 13.92(4) (b) 1, Stats., Register February 2009 No. 638; CR 10-064: am. (6) (a) 2., (b) (intro.), 5. a., Table 82.30-2, cr. (6) (c) Register December 2010 No. 660, eff. 1-1-11; correction in (2), (3) (a) 1., 2., (4) (a) 1., (c) 4., (5) (b) 1., 2. a., (c) 1., (6) (a) 2., (b) 5. a., b., (c), (8) (a), (9) (d), (10) (a) 3., 4., (d) 1. b., (11) (c) 2. d., 3. a., b., c., (g) 2., (h) 1. f., (12) (c), Table 328.30-1, Table 328.30-2 made under s. 13.92(4) (b) 7, Stats., Register December 2011 No. 672.

Amended by, CR 23-006: am. (4) (a), Table 382.30-1, (10) (a) 2. (intro.), c., (c) (intro.), (d) (intro.), (11) (c) 2. e., cr. (12) (f) 3., am. (13) (c), (14) Register September 2023 No. 813, eff. 10-1-23; correction in (4) (a) 1., (16) (e) made under s. 35.17, Stats., Register September 2023 No. 813, eff. 10/1/2023