Modify sections of streets letting water pass through into underground storage and pumping stations.
One of the biggest issues facing urban areas close to the coastline, is increased risk of flooding. We have seen in the United State the effects of hurricane Sandy and its subsequent storm surge on the city of New York, and on cities lining the New Jersey coast. The idea of building a seawall around New York has been proposed many times, but is extremely costly and difficult to build, as well as potentially interrupting to boat traffic and ecosystems in the surrounding area.
When viewing any flooding event in an urban area the first thing that happens is the storm drain system becomes overwhelmed. Not only is this system easily defeated, but there are so few locations, relative to the area of the city, where the water can escape from in the first place. Now imagine that the water from these events, instead of having to find one of the storm drains sporadically placed along the roadways, can fall right through the street itself every X number of feet. This water can then be either put into the existing sewer system, or it can be directed to another, new, storage location where it can then be pumped to an extra-city storage or dumping location.
The basic plan of action would involve ripping up areas of existing streets and installing these “grates” to allow water to drain down. The more complicated part of this redesign would be building the water collection/pumping basins, and attaching the system to the existing sewers. This system is really a matter of subterranean mapping. Simply put, the art of laying pipes in the right places and digging holes to build storage centers. This becomes easier in places like New York where complex mappings of the underground are readily available. Another potential perk to this plan, is that the captured water could be filtered and stored as clean water, which would help to ease potential droughts that can sometimes occur in surrounding areas in the hottest parts of the summer.
Category of the action
What actions do you propose?
On roadways in urban areas implement an advanced drainage system that can be used in situations when the existing systems fail. This adaptation can be divided into two main tasks that would need to be completed complementary to each other.
The first, and more complicated task, would be to build an advanced underground storage system and piping network that could be used to pump water to an extra-city location in a major flooding event. Or, to revamp existing sewer systems to operate properly for this purpose. The latter, however requiring less new infrastructure development, would require major alterations to prevent clog-age from debris that often find their way into the current storm drains etc. The best way to go about the first path, would be to build X number of large volume storage centers under the city. These storage centers would be connected to one another via piping or a large channel. They should also all be level with each other, to try and prevent one from taking on too much of the water that is being drained. If leveling the storage units is not possible, then the system could be split where the storage units do not make up a lattice, but instead operate individually. These units would then be equipped with pumps that could pump the water out of the individual units and into a larger collective channel, where the water could then be either stored, filtered, or dumped away from the city.
Second, portions of the existing roadways, in flood prone areas of the city in particular, will have to be modified to allow the passage of water to the underground system. The simplest way to go about this, is to install grates or a similar strong metallic lattice. Depending on the city/road being modified, these lattice grates should be placed X feet apart from one another for a certain distance, or with regular spacing. For example one could place 3 lattice grates each 20 feet apart and repeat this structure every 300 feet, each of these tri-grate groups could connect to one passage down into a storage unit shared by the entire stretch of road.
The connection between the lattice grates and the storage units is extremely important. There should be enough room between the first large downward pipe and the road so that the water does not overwhelm the system in extreme flooding, but also it must be strong enough to withstand automobiles driving over top. The grate system should be implemented so that the metal extends underground beyond the reach of the road as to provide ample support, while the collection system under would have to take on various shapes to make sure the system is stable. If we use the 3 grates each 20 feet apart example, a simple triangular structure to the draining could be used. Where the far ends of the 3 grates would each lead to an upward sloping ramp that, on the far ends, would have minor pipes that would allow water to fall down at the edges. Directly under the center grate there would be a minor pipe as it would be the “top” of the triangular system. All three minor pipes would lead to a major pipe at some depth that would combine with other major pipes from the other 3 grate units, and this pipe would go into the storage unit. This is just an example of a system that would provide extra support for the road above, especially in the center grate. It is entirely possible that the system will support itself perfectly well, but assuming the worst and it doesn’t, simple architecture can be implemented.
Two final features could also be utilized if the city deemed them worthy or feasible. The first being the previously mentioned water filtration system. If the city felt that the water that was being collected into these storage units was substantial enough to warrant cleaning and storage for usage, this system would allow that easily by simply directing the pipelines to a water filtration plant. The second is the potential to close the main pipe to the storage unit in times where there is only minor rain or minor flooding, and have the water be directed at that time to the typical storm drain system, assuming the new system wasn't already a derivative of it. This could be done easily with a remote opening and closing of the main pipes, and an alternative direction being added to them beforehand, so water would naturally flow into the sewer system during light flooding.
The end goal of these actions is to create a better urban drainage system. By putting water sinks on the roads themselves in regular intervals the city will be able to drain the water caused by flooding at a much more rapid pace. Also the ability to pump this water out of the system and away from the city itself will be a great asset during events like the storm surge caused by hurricane sandy. This system should not be thought of as a stand alone solution, but instead should be considered as a powerful addition to already existing infrastructure. Along those lines cities should do careful planning before attempting a project of this magnitude. Such an immense drainage system would become very expensive at large scale, so precise placement of the new infrastructure is highly recommended as to provide the most bang for the cities buck.
Who will take these actions?
This adaptation will have to be adopted first and foremost by the government, federal and state. The plan is preventative, meaning it will be very difficult to make money on the project, it is instead meant as a measure to keep loss from occurring. For this reason it may not be feasible for the state governments alone to pay for the infrastructure cost, and the federal government may need to set money aside to help cities install this system, especially those like New York that are of high relevance to our society. Construction workers, engineers, and architects, will be needed to make this project happen. Whether these people are provided by the government, or hired from private firms, their expertise is a must. Finally after these actions are completed, there will need to be a sector that can handle monitoring these units in times of crisis. This task can be allocated to any disaster prevention protocol personnel, or can even be monitored by a water company etc.
Where will these actions be taken?
This system should be installed in urban areas that are either prone to flooding, or will be prone to flooding under global warming conditions. The degree and exact locations of the infrastructure in the city, will differentiate depending on the nature of the city itself. Topography of the city will also play a big factor in determining where flooding occurs most, and thus where the most extreme measures of this should be implemented. Again the cost of the project is potentially very high, so maximizing effectiveness is a must. The existing subterranean structures will also have to be avoided, which in some cities might mean deeper storage units, or more small storage units squeezed in between structures. In general the best location for this adaptation would be in “coastal” urban areas that cannot be abandoned and are expected to see an increase of extreme flooding events in the future. Or costal cities that already experience disastrous flooding on a yearly basis. A similar system was proposed in Singapore, where the cost of this project was estimated at a fairly high number. However the benefit seemed to outweigh this cost. A fantastic way to implement this infrastructure would be during a cities early development. This way no existing drain system is in place, and the money that would go towards building a tired out system could be put towards a more advanced, flood conscious, system like the one proposed. This could give developing countries an advantage in that they have effectively a blank slate to work with and no money currently spent on something similar.
What are other key benefits?
As mentioned previously, the water that is captured by the system could be put through a filtration plant and stored to be used as drinking water etc. This could benefit people during the summer when in areas surrounding the coast droughts can occur. One could consider that the ecological damage prevented by utilizing this system instead of a seawall or estuarine blockade is a benefit. This system is entirely confined to a place already developed, and it is subterranean as well, further decreasing the effects that would be seen if it were above ground.
What are the proposal’s costs?
The costs of the proposal are hard to pin down exactly, and are going to be heavily differentiated between cities. A city that already has a mapped out underground is going to get this adaptation at a discount, where as a city that does not know where everything is beneath it will have to ensure that they check the locations before planning. Another factor that goes into cost is how much available space there is in the underground, and also what type of rock is the city sitting on. The magnitude of flooding that would require prevention will also factor into cost. The big spender in this proposal would be the creation of the water storage/pumping units. However, as this is a preventative measure, one should, instead of looking at costs, look at comparisons. Will this be easier and cheaper for our city to install than a seawall? Will this be a faster process that will last longer than estuarine enhancement? It is these cost benefit analyses that each city must calculate individually to determine if this system is the best choice.
Again, the time constraint aspect is going to be heavily dependent on the nature of the urban area the system is being installed in. More flooding, means more infrastructure, which means more time. In general this system appears to be faster than attempting to build an estuarine barrier (given how long certain plants and animals take to settle stably into a new environment), and depending on the size and location of the city, could be faster than erecting a seawall. The city planning, traffic congestion, and available resources will also affect the time factor. In conclusion the timeline and the cost are calculations that should really be done per-city.