Earlier this week, the Minnesota Local Road Research Board released this new video showcasing best practices for local stormwater management. Although it’s primarily a training video for engineers and other public works professionals, non-transportation geeks might also enjoy learning about some of the interesting, innovative techniques being employed in cities and counties across the state.
Those who’d prefer not to watch the whole 14-minute video can skip ahead by clicking on these highlights:
- Woodbury’s stormwater ponds (1:52)
- Washington County’s bioretention gardens (2:56)
- “Green roof” bioretention method (4:02)
- Maplewood’s underground detention system (4:39)
- Greenway stormwater project in Minneapolis (6:03)
- Minnetonka’s hydrodynamic separator treatment system (7:47)
- Arden Hills’ infiltration (swales) system (8:26)
- Shoreview’s permeable pavements (9:52)
- Ramsey-Washington permeable pavement project (11:11)
- Tree boxes/trenches in Ramsey-Washington (12:06)
Overall, the video gives you an appreciation for the incredible amount of planning and work that goes into managing stormwater runoff — a task that’s critical to protecting the state’s waterways from pollution (but which many people no doubt take for granted). For those who want to learn more, the best management practices showcased here are examined in greater detail in a recent LRRB report, “Decision Tree for Stormwater BMPs,” which is available for free on the LRRB and MnDOT Research Sevices websites:
In Minnesota, with our often wildly unpredictable weather and constant freeze-thaw cycles, potholes are a fact of life. Anyone who’s climbed into a motor vehicle in the last month or so has doubtlessly encountered countless reminders of this dismal reality. Fortunately, we have a small army of public works professionals devoted to eradicating this perennial nuisance. The Minnesota Local Road Research Board recently produced this video, which nicely explains the various methods used to combat potholes in Minnesota.
Potholes form when water invades cracks in the pavement and infiltrates the soil beneath it. When that water freezes, it stretches the road surface, causing the fractures to expand. After a few cycles of freezing and thawing, the pavement begins to buckle and eventually collapses under the weight of passing traffic, creating disruptions in the road’s surface.
Road crews use a variety of methods to fill potholes. The simplest method is the “throw-and-go” procedure, in which workers simply shovel an asphalt mixture into the pothole and pack it down until the road’s surface is smooth. A related method is “throw-and-roll,” where the patch is compacted using an asphalt roller.
Other methods include:
- “semi-permanent” patching, in which workers clear the pothole of moisture and debris and then square the edges with a pavement saw before applying the patch;
- “spray injection,” which involves using specialized equipment to blast water and debris out of the pothole before spray-filling it with asphalt mix and finally applying a dust coat of dry aggregate on top; and
- “slurry” or “microsurfacing” crack filling, in which a slurry of aggregate, asphalt emulsion and mineral filler is placed over a crack in the pavement and leveled off using a squeegee.
This Asphalt Pavement Maintenance Field Guide (PDF), co-funded by MnDOT and produced by CTS, provides a handy how-to guide to pothole patching and other types of pavement repairs commonly applied by public works professionals in Minnesota.