Minneapolis Department of Public Works

Public Works

350 South 5th Street
RM 203 City Hall
Minneapolis, MN  55415-1390

Disconnection Information for Commercial and Multi-Unit Residential Buildings

Usual sources of prohibited discharges

Permit Required

A permit is required before disconnection work can begin. There is no fee for a Rainleader Disconnection Permit. If disconnection work is not completed within the timeline of the permit, or if a permit application is not received by the due date indicated, the City may issue administrative citations and fines. Download a Commercial Permit Application (pdf).

Inspection Required

The disconnection must be approved by the City. Be sure to schedule an inspection with the City after disconnection work is completed but before it is concealed.

What To Look For

If a building has a flat roof and was constructed prior to 1960, it’s likely that one or more roof drains have been piped internally and discharge to the sanitary sewer.

To determine if this is the case, start by visually inspecting the roof. Most roof drains are located near the center of the roof or in a lower pitched area of the roof and terminate with a strainer dome. Typically, buildings with internally piped roof drains also have one or more overflow scuppers. These openings in the building wall or parapet help drain water if the roof drain should become plugged.

Measure or step off roof drain locations in relation to the overall structure. The route rainleaders take down through the building are usually vertical with few utilizing offsets.

Next, go to the lowest floor of the building and find the rainleader using the roof measurements as a guide. It will be a cast iron pipe 4, 5, 6 or 8 inches in diameter with a cleanout fitting at the base.

In many older structures, the rainleader is exposed in a mechanical room, laundry, storage space, etc. It may come down in a tenant space or in a closet. It may be exposed or may have been boxed-in. Sometimes rainleaders are found inside finished walls. Tracing plumbing lines may require extensive detective work and possibly opening up walls or ceilings.

If the rainleader runs directly into the floor, it likely is tied into the building sanitary sewer and must be disconnected. If there is a storm drain in the street, or if the rainleader makes some other type of connection in the building, additional tracing or testing should be done.

Tracing and testing can verify a connection to either the storm drain or sanitary sewer. Smoke testing, dye testing, and video camera inspections are some methods used to make this determination.

Primary Ways to Divert Rainwater

See illustrations of common commercial connection methods

There are two primary ways to divert rainwater out of the sanitary sewer:

Some buildings have flat pitched roofs where rain or snowmelt flows to one end and drains through a downspout or a perimeter drainage scupper. The downspout can either discharge onto grade or connect to the sanitary sewer through a standpipe. If the downspout is connected to a standpipe, the downspout can be redirected to discharge onto grade and the standpipe suitably plugged or capped. In no case shall water from roofs be allowed to flow on to a public sidewalk.

Cost Estimates

Here are some estimated costs for disconnection of typical roof drains for multi-unit residential and commercial buildings. These estimated costs do not include the cost of any or all permits (multi-unit and commercial buildings may require additional permits depending on the work required to disconnect roof drains and reconnecting, if necessary, to the City’s stormwater drains). These estimates are from spring 2013.

Disconnection of Typical Roof Drain in Multi-Unit Building

With 4-Inch Piping

 

Includes Material & Installation

Cost

30 feet of 4 inch cast iron pipe

Includes cast iron piping, drilling a hole through wood or masonry walls*, labor and associated material costs.

$1,780

*Core-drilling a hole through solid concrete or block (if necessary)

$942

Optional bronze downspout nozzle with galvanized nipple

$355

Optional concrete splashblock

$70

Total cast-iron cost (approximate maximum)

$3,147

Piped using 4 inch PVC

Less 30% for time and material = $2,203

With 6-Inch Piping

 

Includes Material & Installation

Cost

30 feet of 6 inch cast iron pipe

Includes cast iron piping, drilling a hole through wood or masonry walls*, labor and associated material costs.

$2,508

*Core-drilling a hole through solid concrete or block (if necessary)

$1,062

Optional bronze downspout nozzle with galvanized nipple

$686

Optional concrete splashblock

$80

Total cast-iron cost (approximate maximum)

$4,336

Piped using 6 inch PVC

Less 30% for time and materials = $3,035

Commercial Disconnection from Building to Storm Drain in Street

Contact an outside sewer and water contractor to evaluate the site and design a plan for disconnecting from the sanitary sewer and connecting to the storm drain in the street.

Installation charge will vary plus or minus depending on conditions of work site: depth of excavation, utilities present in the street, access to storm drain, location of storm drain main in relation to building, traffic concerns, soil conditions, etc.

Above Ground Discharge, Disconnection Inside Commercial Building

 

Material

Cost

Three-inch cast iron piping

$45.84 per foot

Four inch cast iron piping

$53.64 per foot

Six inch cast iron piping

$75.90 per foot

Last updated Jul. 22, 2013