Ground Water Contamination and Use of Septic Tanks in Florida Keys Area - Research Paper Example

Ground Water Contamination and use of Septic Tanks in Florida Keys area Introduction While Florida Keys has Gulf of Mexico on one side and Atlantic Ocean on the other side, it covers a vast area of around 150 mile starting from the southern tip of the state. It is rich in the natural coral reef and marine habitats that face the real environmental threat due to man made mistakes and faulty sewage system, which causes serious damage to the natural marine atmosphere. The human waste seepage into the aquatic environment has endangered the living coral reef and other marine living organism, forcing closure of some of the beaches in the area. The problem is so acute that the change in the natural green color of seawater is visible by the naked eye in almost all the 25 islands of the area. Due to the rapid development of the area, the permanent living population for the area has grown to around 85000, against that of almost 10000 living there a few decades back. This along with the incoming tourist rush has put real pressure on the infrastructure of the area, particularly its human sewage disposal program. Several studies conducted during the recent past have shown the evidence of seepage from human sewage to the living area of coral reef. This has been mainly due to the leakages from outdated or mismatched septic tanks and cesspits. Although around 30% of the resident population is served by the central sewerage system, others depend on the network of outdated septic tanks and cesspits. Although, funds are being organized to repair and replace the sewage system by the US Congress in consultation with resident locality members, United States Environmental Protection Agency, South Florida Water management District and Florida Keys Aqueduct Authority; the total cost to rectify the system would range from around 554 million to 1.1 billion dollars. The main hesitation from the local residents to update their sewage system arises due to the unaffordable cost involved, which can go up to $ 10000 to $20000 for each unit, while everyone is keen to clean their mess, as they are aware of its damage to the coral reef and marine environment. Hence govt. help or subsidy is nessary.........(Key Sewage, CBS Radio Network) Non Point source of pollution While the point source of water pollution refers to the industrial pollutants, the non point sources of pollution affect Florida Keys area, as it has very few sewage disposal or treatment systems that are needed by any urban landscape. The non point sources of pollution also include sediments from construction sites, fertilizers or other agriculture products, bacteria from livestock as well as the human waste leakage from septic tanks and cesspits. As the centralized sewage treatment plants did not find favor from the people of this area, due to its high expenses and rocky sub terrain of the area, people have resorted to the use of septic tanks for treating their sewage disposals. Unfortunately, the untreated waste was directly pumped into the ocean until recently, (till 1989), which caused a great damage to the natural resources of the area. However, during the last ten years, a few centralized sewage treatment systems have come into place. While they may not pose any threat to the environment individually, their collective damage to the atmosphere is now beginning to show up. Apart from almost 750 waste disposal wells that are being constructed and maintained by the department of Environmental Protection, private operators are active in the Keys area. They provide package units for sewage treatment and disposal. Accordingly, wastewater is treated, in around 350 package units, and then pumped deep into the ground. Some of the settled out sludge and solid waste is further sent to Miami for more treatment of the same. ..........(Darden,...Wastewater... pages 3-7) Non-point source water pollution impact on Florida Keys As coral reef colonies are extremely sensitive to any change in the water quality, studies conducted for this purpose around the Florida Keys area have revealed that the coral reef have started showing symptoms of the diseases caused by human waste contamination, which has resulted in the increase of nutrient and bacteria levels around the area. The coral reef are located between four to seven miles, offshore from the islands in the Atlantic Ocean and there are several national parks in the area that preserve the coral reef, within their boundaries like Biscayne National Park, John Pennekamp Coral Reef State Park and Looe Key National marine Sanctuary, among others. They serve as the barrier for Coral reef ecosystem, which is unique for the complete continental United States, within the Florida Key area. Apart from this, the area having a vast treasure of natural fauna and flora that is getting affected with the contamination caused by the pollution from human waste, as it endangers the human health as well. As corals are most fragile ecosystems, found on earth, they depend on sunlight being absorbed by them in the nutrient free clear water. This requires them to remain mostly in shallow waters, close to the shore. This also makes them vulnerable to environmental hazards posed by ground water seepage, developmental work on the shore and even the physical harm caused by divers and boat collusions..... (Darden,...Wastewater... pages 5-8). Geology of Florida Keys area The presence of limestone in thick layers in the Florida Keys and Bay area facilitates the easy flow of ground water. Since the water here has mostly a constant level, the groundwater flows back and forth between the two water bodies, with Atlantic Ocean on one side, which results in a sort of tidal pumping. This is the result of water being pushed through the limestone to the west side of the islands from the eastern side as water level rises on the eastern islands due to Atlantic Ocean high tide. While the water flows towards the ocean from the bay area, at the times when the Atlantic Ocean tide is low. This down hill flow of water into the ocean carries with it all the pollutants and other harmful bacteria that can reach further eastwards towards the reef habitation in the ocean itself. The developmental work done in the Bay areas have caused breaking of coral barriers by the canals that came up due to the dredging operations in the area. The groundwater has an easy flow through these canals to reach the Florida Bay and Atlantic Ocean, which is the home for coral reef. However, the work could not be suspended, as it was necessary to support the expanding population demands in the area. The movement of waste water along with the oxygen deficient nutrients and other bacteria became easier, due to such manmade canals, to reach the ocean and coral reef faster.....( (Darden,...Wastewater... pages 9-10) Use of septic tanks As per the study conducted by the University of Georgia, the sewage from ground water finds its way to coral reef and other habitats of Florida Keys area. This has resulted in serious threat to the human wealth as well as the marine environment of upper Keys area, in particular. The use of septic tanks and disposal wells to treat the human sewage has resulted in the contamination of submarine groundwater, thus affecting the marine organisms largely. On the investigation of samples of surface as well as ground water and corals, from this area, the US geological survey staff in Tallahassee found the presence of human viruses and fecal bacteria in the same. The observations made during the study revealed the presence of high-level bacteria coming from such viruses, more predominantly in the stations that are close to the shore. Therefore, this could suggest that cesspits and septic tanks may be the sources of such pollutants caused by human sewage, as they are found to be in widespread use throughout the area. While the viruses were found more active and abundant during the rainy season, their genetic behavior suggested that most of the diseases are the direct affect of human feces and urine, polluting the subsoil and ground water. Hence, the need to install new waste water management systems, including centralized collection and advanced waste treatment facilities was strongly felt, as reaffirmed by Bill Kruczynski, Florida Keys Program Scientist for the U.S. Environmental Protection Agency. While this should meet the standards set by Water Quality Protection Program (WQPP) for the Florida Keys, the sewage treatment systems should also meet the recommendations of US Environmental Protection Agency.............(Fahmy, 2007) Septic tank design While it is not true, that septic tanks are the devices that treat sewage, and the soil filters the remaining water to make pure underground water, these tanks are simple concrete structures that can hold sewage for almost two days. During this process, the solids of the human waste settle at the bottom and lighter particles present in the wastewater float to the top, which results in the reduction of sewage strength due to the presence of water breathing bacteria formed. While the solids separated from the liquids flow out through a pipe into the drain field, the treatment of this waste starts here in the field, due to the presence of air breathing bacteria present in the soil. Since this bacteria feeds on the bacteria and other organism present in the effluent that has stretched out in the field. Hence, the wastewater and sewage treatment occurs naturally. There are two types of septic tank design as detailed below. Design based on Gravity type system This system uses the new vault technology, as can be seen in the picture below: (Source: http://www.eco-nomic.com/indexsdd.htm ) This technology does not make use of any drain rock or center pipe to spread the soil. Instead, the effluent spreads on the floor of the trench to reach the soil. As vaults have larger capacity to store the effluents, it is easier in construction as well, as there is no need for any drain-rock that necessitates problems with its transport to the site. However, the vaults are found to be expensive as compared to the traditional drain-rocks. The existence of rapid corrosion in the pipes due to the effluent water conditions has necessitated the replacement of components like pipes and other parts, with plastic fabrications, which show more resistance to rust and decay as compared to concrete parts used in the traditional concrete septic tanks. Nevertheless, concrete septic tanks are still in use, as structural designers prefer these to the plastic or fiberglass septic tanks, at certain locations. While in the standard gravel type drain field, there are trenches that go deep up to three feet, with same width, the plastic distribution pipes of 4 in. diameter with capped ends, are placed in each trench. Finally, the drain-rock foot is placed into the trench that surrounds the pipe. Although the four inch perforated pipe does not distribute the wastewater perfectly into the soil, the gravity design ensures the same as this system is still in use in some counties, due to its ease in construction. However, coarse or shallow soils may require pressure system to do the job......(Septic System Design, Gravity type) Septic system based on pressure type design The system design of pressure type uses the pump that is housed at the bottom of the concrete tank to allow the flow of effluent to the soil using the pressure-generated by the pump. A picture of such septic system is given below. As can be seen, the drain-filed vaults have a center pipe that carries the forced effluent intrusion caused by the pump pressure.........( Septic System Design, pressure type) (Source: http://www.eco-nomic.com/indexsdd.htm ) The pump should be activated before the settled solids and effluents occupy most of the space at the bottom of the tank, thereby reducing further process of settling for the effluents. If the pump is not started in due time, the sewage back up problem may occur that will damage the whole system. However, a few precautions should be taken when working with septic tanks. These include using of proper pump, based on the size and usage of the tank, apart from not using any chemicals or additives at the place of septic tank pumping. Apart from the above, few house owners are thinking of shifting to a professionally managed treatment system that will replace the old cesspits and septic tanks. Therefore a system that prevents discharge of high pollutants to the sea and other water bodies, and which reduces the expenses that may be needed for laying sewer lines, would be the ideal alternative to the old septic tank system in the Florida key area.....(Mancl & Slater, Septic System Maintenance) Rules for proper functioning of septic system The following guidelines are needed for proper functioning of a well-designed septic system that aims to minimize the ground water contamination Soil that does not contain too much clay or sand is ideal for the proper functioning of the septic system. Excess clay in the soil prevents wastewater to percolate properly, while too much sand will not allow the wastewater to be treated by the soil microbes properly. Water should be below the depth of the soil treatment as it gives the opportunity to wastewater for being treated in the unsaturated soil, above the ground water level. With the presence of oxygen in the soil, the treatment is more effective before the wastewater merges with the ground water. For effective treatment of wastage, septic systems that utilize sufficient open space are better as it reduces the loading of ground water in a concentrated manner by the effluents present in the human waste. While the need is to have a proper design of septic system that matches with the size of the family using it, the type of wastewater and soil conditions should be analyzed for finding an effective system. However, no chemicals or greases should be disposed off through the septic system route as they can damage the parts of the system. In addition, the water conservation helps a lot in the long-term proper functioning of the system. Proper pumping of the septic system is essential as the absence of it may cause clogging and ultimately damage the septic system. The following is a diagram of a typical septic system, (Source: http://ohioline.osu.edu/aex-fact/0740.html) Septic tank functions A proper septic system requires to treat the wastage before allowing the percolation of liquid waste into the subsoil while protecting its absorption capability. In this direction, important functions of the septic system are detailed below: Separation of solids from liquids The two types of solids, heavy and light form the sludge and scum while they settle at the bottom of the tank, while sludge settles at the bottom of the tank, grease and other light solids rise to the surface in the form of scum. This gives way to the clarified liquid to be discharged into the drain-field for soil absorption, as the solids break down during this process. This is expressed in the figure below: (Source: http://www.fcs.uga.edu/pubs/current/C819-2.html) Biological process for the break down of solids and liquids The treatment is biological and natural due to the interaction of anaerobic and aerobic bacterial condition, while break down of solids and liquids takes place in the absence of oxygen in the tank, thus creating “septic” conditions. The bacteria at the subsoil wait for these anaerobic organisms to feed on them. Sludge and scum is stored at the bottom of tank As sludge settles at the bottom of the tank, the lighter solids in the form of scum float at the surface of semisolid liquids present in the tank. However, with the passage of time these solids compress to take little space and volume in the tank area. In addition, the warm climate facilitates the break down of solids in a natural manner, which may reduce the need for pumping out these, using a pressure pump. However, in the winter climatic conditions, the solidification is more aggressive, which needs pumps for such wastage to be thrown out. Solids must be restrained to enter and clog a drain-field, which will damage the total system, itself. At the same time, large quantities of grease can damage the septic system, as it can cause soil plugging, in the process. The following diagram indicates the affect of septic system on the ground water: (Source: http://www.fcs.uga.edu/pubs/current/C819-2.html) Larger lot sizes are preferred over the smaller ones, as they reduce the chances of effluent percolation to the ground water, as pathogens present in the effluent breakdown the bacteria present die out due to the filtration process of the soil........(Hammond, Septic Tank Design) Federal regulations regarding pollution in the Florida Keys The following regulations have been enforced in this direction for ensuring pollution free water discharge into the Florida Key area: Florida Keys National Marine Sanctuary and Protection Act This act aims to support the biological diversity of the area, while protecting the coral reef habitation therein. As per this act, the commerce secretary shall develop a comprehensive management plan to address the area of its regulation, enfacement and monitoring. The act is particular in directing the EPA administrator and Florida Governor to formulate a comprehensive Water quality Protection Program that would aim at tackling the issue of point and non-point sources of water and sewage pollution in the area. Clean Water Act Although this act has been in place for more than twenty-five years now, it has not been able to combat the water pollution problems of the area, as the act looks into the pollution problems caused by only point sources.....( Darden,...Wastewater... pages 11-13) Conclusion While laying of central sewer lines may be an expensive job due to hard rock cutting operations involved for the Florida Key area, the need is to find a comprehensive and viable alternative sewage treatment system that can reduce the faults, which are observed in the present septic systems. Proper reconstruction of these outdated systems with new designs and reliable parts can be effective in combating the pollution problem to a certain extent. ______________________________________________________________ BIBLIOGRAPHY WORS-CITED Darden Heather, “Waste water in Florida Keys...”, available at : http://www.law.fsu.edu/journals/landuse/vol162/darden.pdf 9accessed on 25th Oct 2009) Fahmy Sam, 2007, “ Study finds contaminated water reaching Florida’s Offshore Keys” Available at: http://www.innovations-report.com/html/reports/environment_sciences/report-87937.html (accessed on 20th Oct 2009) Hammond Cecil, “Septic tank design and construction”, available at: http://www.fcs.uga.edu/pubs/current/C819-2.html (accessed on 27th Oct 2009) Key Sewage, CBS Radio Network, 2000, available at: http://ohioline.osu.edu/aex-fact/0740.html (accessed on 25th Oct 2009) Mancl Karen & Slater Brian, “Septic System Maintenance”, available at: http://ohioline.osu.edu/aex-fact/0740.html (accessed on 28th Oct 2009) SOURCES USED Darden Heather, “Waste water in Florida Keys...”, available at : http://www.law.fsu.edu/journals/landuse/vol162/darden.pdf 9accessed on 25th Oct 2009) Read More