"Wisdom begins in wonder" – Socrates
Category: Urban Systems
Sewer Capacity
12/05/25
“How can we represent the total amount of wastewater a sewer can handle?”
Sewers are one of the most important sanitary inventions. However, they can only handle a certain amount of wastewater, called Sewer Capacity, before they fail. Sewer capacity is dependent on a multitude of factors, such as pipe length, diameter, slope, material, as well as existing blockages and water speed. Sewer capacity may require expansion if a city is rapidly expanding.
MS4 Operators
12/04/25
“Who is responsible for managing MS4 systems?”
MS4 systems are a wonder of modern technology. In the U.S., whoever owns and operates these systems, whether it’s a city, county, or some other entity, are designated as an MS4 Operator. MS4 operators are legally required to develop and maintain a stormwater management program and to review stormwater pollution prevention plan applications.
Stormwater Management Programs (SWMP)
12/03/25
“How do municipalities plan for stormwater management?”
Nearly every part of the world receives stormwater, whether it’s the Syrian desert or the Amazonian Rainforest. The runoff from this stormwater can carry pollutants from municipalities to nearby water bodies. Towns and cities are required to devise a plan for managing stormwater pollution transport. In the U.S., these plans are called Stormwater Management Programs (SWMPs). The Clean Water Act requires public entities that operate MS4 systems to develop stormwater management programs.
Impaired Water Bodies
12/02/25
“How does the EPA classify water bodies that don’t meet water quality standards?”
Water bodies all over the world have different levels of pollution. In the U.S., some water bodies are so polluted that they don’t meet water quality standards, leading the EPA to classify them as Impaired Water Bodies. Impaired water bodies are eligible to have a total maximum load pollution limit and environmental review for projects that may impact them to protect against further degradation.
Grade Separation
12/01/25
“How can we separate different transportation paths by placing them at different heights?”
Transportation routes are one of the most fundamental parts of how people move around, whether it’s a pedestrian street, a set of train tracks, or a highway. However, sometimes we may not have enough space for all paths to run together. So how can we use our engineering and planning mindsets to solve this? Well, what if we were to place different transportation paths at different heights? With Grade Separation, the same space can hold more potential paths. Examples of grade separation include the pedestrian and car bridges over 580 in Oakland, the bicycle lanes in New York City’s Rockaway Corridor, and the NH 248-BB in India.
Junctions (Transportation)
11/27/25
“How can we describe the places where two different travel paths meet?”
Travel paths are the core of moving around, whether it’s a highway interchange or a train on a multilane path. The intersections of travel paths are called Junctions. Junction design is vital for transportation engineering since this could drastically affect traffic, commercial viability, technical feasibility, and travel flow coordination.
Trunk Sewer Lines
11/26/25
“Are there sewer pipes so big you can walk through them?”
Main sewer lines carry water from home lateral pipes to more centralized zones. These main lines usually feed into Trunk Sewer Lines, large diameter pipes that feed into wastewater treatment centers or even . Trunk sewer line diameters can be so big that a person can walk through them, but the gas released from the raw sewage is dangerous enough that people will need to wear protective equipment while walking through. Trunk sewer lines are more likely to fail than smaller diameter pipes because of their large size, forcing municipalities to take extra care of these assets.
Main Sewer Lines
11/25/25
“What are the sewer lines that connect waste from buildings to larger piping systems?”
Sewers transport waste and stormwater from entrance to release or treatment. In between the small building-level lateral sewers and larger trunk/interceptor sewers are Main Sewer Lines. Main sewer lines are (as the name implies) the main connecting in the stormwater artery system. Main sewers are some of the longest pieces of infrastructure that cities own and require careful maintenance.
Arterial Roads
11/24/25
“How do we classify roads less intense than highways but more intense than highways?”
Picture this. You live in a U.S. suburb, and you need to drive to get groceries. You know that you will have to leave your cul-de-sac neighborhood and get on a road that has highway access, but you will not enter one. What type of road are you on? Well, these roads are typified as Arterial Roads. Arterial roads are vital in connecting dense activity centers such as downtowns and airports to each other and providing entrance to freeways. Examples of arterial roads include Queens Avenue in NYC, Wilshire Boulevard in Los Angeles, and Grand Avenue in Oakland.
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