Every city has water supply challenges, no matter how much water surrounds them. While the challenges of a city like Phoenix, Arizona are much different than that of one like Miami, Florida, the challenges still exist. In fact, part of the problem that Miami is facing is due to rising sea levels and the capacity of the city to handle the large rain events that have been happening.
Additionally, Miami pulls its drinking water from the Biscayne Aquifer which is extremely close to the surface. This makes the water in the aquifer easily accessible, but it also means there are shorter and more direct pathways for contamination to get into the water source.
Here, we explore the increasing issues in Miami with water supply and quality and ways in which on-site water management helps solve these issues. Miami is often considered an area with abundant water and thus immune to water supply challenges. We more often think of an excess of water causing flooding and runoff exacerbated by sea level rise. In fact, both are concerns and both can be helped by better on-site water management.
Contamination Risks Facing Miami
When breaking down the risks facing any city, engineers and scientists will look to two different areas of possible contamination: surface water and groundwater.
Surface Water Contamination
The challenges facing Miami in terms of surface water contamination have been escalating, and most water issues in the Miami area are surface water related phenomena. Each of the contamination risks is a problem on its own, but when all of them are considered together, the situation may grow to a crisis point.
In addition to the property damage, safety, and nuisance of flooding, dirty, contaminated water is washed into waterways. In the case of Miami, this is more immediate than in other areas. The added runoff is caused by several factors including:
Impermeable surfaces – development: As in any developed area, development leads to paved areas and rooftops from which stormwater runs off. In the case of Miami, this water reaches canals and Biscayne Bay almost immediately to affect water quality and flooding. Added to this are the ever-higher tides that are causing fair weather flooding.
Increased rainfall intensity: Miami’s rainfall during heavy rains has increased over 7% over the last 50 years. While this may not sound like much, it can be the difference between flooding and not flooding. The Union of Concerned Scientists estimates that by 2045, as much as 29 percent of Miami Beach and 26 percent of Key Biscayne could be “chronically inundated,” which UCS defines as flooding twice a month. This will be due to the combination of heavier rainfall, higher tides, and more impervious surfaces.
Discharge of Fats, Oils, and Greases:
Miami is under an EPA consent decree to reduce the wastewater discharge that is contaminating Biscayne Bay. Fats, Oils, and Greases (FOG) are significant water contaminants and are a particular problem in Miami. They directly affect local waterways and can have adverse effects on wildlife and the quality of water in those areas. FOG can clog pipes and cause raw wastewater discharge into major waterways such as Biscayne Bay which in turn reaches the Biscayne Aquifer, Miami’s main water supply.
Once you flush the toilet or turn off the sink you probably don’t think twice about where that water is going, but building discharge is a huge issue. In fact, many building permit requests are being denied in certain areas of Miami-Dade county because they simply cannot handle any more wastewater.
Overloaded Treatment Plants
Treatment plants can physically only handle a certain amount of water each day and are limiting growth in Miami. When a major rainstorm occurs, the systems physically cannot handle the amount of water flowing through them, so raw wastewater is discharged into local waterways. Again, this contaminated water eventually makes its way into the Biscayne Aquifer.
About 20 years ago, limestone quarries were mined in close proximity to the Biscayne Aquifer. Now, contaminated water, including mining chemicals, has even less distance to travel to get to the aquifer.
The growth of Miami coupled with the increased amount of rainfall in the last few years creates a perfect storm for water contamination. In the next few decades, with no changes made to water systems, it is anticipated that parts of Miami Beach and Key Biscayne could be flooding as much as twice a month.
It is possible that the groundwater can be contaminated by water or contaminants that are underground. This is fairly unique to the location and structure of Miami.
In the Miami area, the aquifer is quite close to the sea floor and saltwater can seep into its base. This occurs when sea levels rise and added pressure is put on the walls of the aquifer. This salt water intrusion is contaminating the Biscayne Aquifer
Septic tanks are used throughout Miami-Dade County with over 90,000 in use. These tanks are known to leak and waste can easily get into the groundwater. Since Biscayne Aquifer is so shallow, this contamination is clearly a major driver with acetominophen (Tylenol) being detected in many areas.
Miami has many underground storage tanks are a great way to store chemicals to keep them safe from adverse weather or tampering, however, it is very common for them to leak. These tanks can sometimes be mere feet away from where groundwater runs. Many Miami-Dade area sites have been designated as EPA superfund sites and have been proven to be contaminating the aquifer.
All of these problems might seem overwhelming and nearly impossible to prevent, but there are proven ways to reduce contamination.
The solutions typically offered to all of the above problems tend to be large scale in nature. Steps like increased release from the Everglades, large city sewer expansion, and piping and pumping infrastructure replacement-in-kind. However. there are other easier and elegant solutions that can be managed site by site with a greater effect. Let’s take a look at how on-site water management can be used to solve these water issues.
Many people jump straight to big, overarching solutions, but those tend to be expensive and hard to implement and maintain. It can actually be more efficient to work on a lot of smaller-scale solutions as opposed to one big one.
There are a wide range of options engineers, architects, and developers can utilize to manage the water coming in and going out of a building site. The solutions can range from simple and low cost to more complex and each has a unique and positive effect on water management.
Rainwater collection is a simple and efficient way to help reduce runoff and prevent flooding as well as to provide a very viable water supply, taking load off the Biscayne aquifer. It is relatively low cost and low maintenance depending on the capacity of the system.
In a rain-heavy area like Miami, rainwater can be collected and used for non-potable uses like toilet flushing, irrigation, and cooling tower make-up. It is also used for drinking water in many cases. Using clean rainwater as a drinking water source is healthier than municipal water with contaminants like carcinogenic chlorine and its byproducts and pharmaceuticals. It has been calculated that a non-potable rainwater system on a single-family home could supply up to 60,000 gallons of water per year and an order of magnitude more for large buildings. Potable rainwater systems can approach full off-grid water supply.
By reducing both the amount of water that needs to be treated centrally and being pulled from the aquifer, the benefits of rainwater collection are twofold. First, they lessen the load on wastewater treatment facilities, specifically during rain events. Second, there will be fewer voids in the aquifer and saltwater intrusion will lessen.
As one of many stormwater management BMP’s (best management practices), rainwater collection offers the same runoff reduction plus adding a viable water supply by using collected water on-site beneficially.
Greywater is water coming from showers, laundry, and bathroom sinks. It has less contamination than blackwater, which includes toilets and kitchen discharge. A greywater system treats water onsite for reuse typically for non-potable uses.
There is a copious amount of laundry, bath, and shower water that comes from buildings. In fact, it is the largest wastewater contributor. Well over 50% of all domestic wastewater can be captured as greywater. This has the obvious effect of reducing discharge by over 50% to reduce load on downstream infrastructure, which also can be on-site. This means in effect that a 20-story high rise will discharge more like a 10-story high rise (rough estimate). The impact on the environment and development opportunities could be huge. By treating captured greywater to a standard required for toilet flushing, cooling tower make-up, irrigation, and laundry, the strain on municipal water treatment and overflows will be greatly reduced.
Likewise, reduction of municipal well water demand is up to around 40%. This can slow saltwater intrusion and preserve underground supplies.
Low maintenance, reliable greywater systems are on the market that produce very high quality water. Florida requires that greywater systems which reuse water be certified NSF 350. Look for those types of systems when selecting a greywater system.
Blackwater is wastewater coming from toilets and kitchens, which tends to have a high biological load (BOD), fats, oils and greases (FOG), and solids. For around 90,000 residences in Miami-Dade County, this means it goes to a septic tank. Rather than allowing lightly treated water from an inefficient septic tank to leach into water supplies, it is relatively easy to treat wastewater and blackwater to a standard in which it can be used on-site for drip irrigation.
One of the more easy and obvious solutions is to convert the 90,000 septic tanks in Miami-Dade County to active aerobic systems. There are systems on the market that allow for retrofits to a reusable water quality without having to replace the tank. The net cost of such a solution would be a small fraction of the proposed city sewer extensions being talked about, even including monitoring and regulation. Since water from such systems is suitable for drip irrigation, there can be zero discharge and no seepage of contaminated water to the aquifer. When coupled with a greywater system, the actual amount of water requiring treatment is more than cut in half. This actually makes treatment easier with stronger, more concentrated effluent producing cleaner discharge.
Like many other US cities, Miami has an EPA consent decree and significant issues with clogged piping infrastructure cause by fats, oils and greases, A.K.A. FOG. Restaurants are the main contributors to FOG and the focus of many of the solutions. By eliminating discharge and by monitoring interceptors and grease traps, Miami can go a long way to preventing FOG related issues downstream. This in fact is happening with programs being implemented by Miami-Dade County.
Worldwide, on-site water management is collectively making a big impact make an impact on the water supplies, water quality, reducing discharge and slowing the threat of saltwater intrusion. These techniques are just starting to be adopted in the Miami area, and will, if widely adopted be part of the solution to its water challenges.
For more information, please contact Ecovie Water Management at Call:+1 833 ECOVIEE.