Trench Drains.
Milwaukee Code of Ordinances § 225-6
in effect225-6. Trench Drains.
1. Trench drains for paved lots or parking areas shall be installed entirely across points of ingress and egress of the premises and shall be connected to a storm or combined sewer. The trench shall have a minimum width of 6 inches and a minimum depth of 8 inches and may be constructed of concrete, cast iron, steel or an approved prefab unit. When constructed of concrete it shall have a minimum thickness of 6 inches. When a prefab unit, cast iron or steel unit is used, it shall be installed according to manufacturer's specifications. Where a trench drain is not practical, a catch basin or storm inlet may be used when the grade can be sloped away from the public right-of-way.
2. The trench shall be covered with an approved metal grate and frame having a minimum width of 6 inches and of sufficient strength to sustain the weight of traffic to which it will be subjected. Grates and frames in excess of 6 inches in width shall be proportionately stronger. Manufacturer's ratings will be accepted.
3. Steel load bearing grate bars shall have a minimum width of one and 3/16 inches and a minimum thickness of 3/16 inches set on edge spaced one and 3/16 inches on center.
4. All steel grating shall have the load bearing bars running the short distance and shall be continuously banded with bars on both sides across the face of the load bearing bars with the same material and size as the load bearing bars. Such banding bars shall be welded to the load bearing bars with a 3/16 inch fillet weld at least one inch long; one-quarter inch square twisted cross bars or equal on 4 inch centers shall be welded to the load bearing bars the length of and parallel to the banding bars.
5. All steel grates shall be set into a steel curb angle frame a minimum of one and 1/4 by one and 1/4 by 3/16 inches and set flush with the top of the grade or trench. Bent anchors a minimum of one by 3/16 by 5 inches long or equal shall be welded to the outer face of the angle frame at 3 foot intervals or less.
6. Cast iron grates shall be rated "heavy duty" and shall have a minimum thickness of one and 3/4 inches and a minimum weight of 25 pounds per lineal foot. The drainage opening areas shall be a minimum 30% of the area of the grate. All cast iron grates shall be set into a cast iron or steel curb angle frame flush with the top of the grate or trench. Steel frames for cast iron grates shall be constructed the same as required for steel grates. Cast iron frames shall be a minimum 14 pounds per lineal foot and shall have integral cast anchors and tie lugs at 3 foot intervals or less.
7. Where interior trench drains are installed, the trench shall have a minimum width of 6 inches and a minimum depth of 8 inches and shall be constructed the same as outside trench drains. The frame and grate shall be as specified in this subsection.
Source: City of Milwaukee Legislative Reference Bureau, Milwaukee City Charter and Code of Ordinances (city.milwaukee.gov master PDFs)URL: https://city.milwaukee.gov/ImageLibrary/Groups/ccClerk/Ordinances/Volume-2/CH225.pdf#page=5Fetched: 10/26/2026