Combined Sewer Discharge
A combined sewer system is a sewage collection system that uses single pipe system to collect both urban run off from roofs and streets and from the sewage. This system was developed in the early twentieth century because of it’s cheapens of being a single system. By then, most cities did not have sewage treatment plant but today they are found in most parts of the US mostly concentrated in the GreatLake and North east region.There have been several urban water technology implementation and management strategies since the 1800s. Two types of public sewer systems are found in the US; first there is the sanitary sewer system and the combined sewer system.
They collect water at a central point for disposal, or decentralization and treatment has been one of the strategies.A CSO is discharged from a combined sewer system into the water stream. CSO occurs during heavy rains when there is overflow of sewage waste which exceeds the capacity of combined sewer system and the water treatment plant.This paper will argue the fact that CSO is not safe for the environment and to the public because of the impact it has on air and water pollution, illness, recreation and commercial fishing.
The problem with CSOs
Since the twentieth century, municipalities have constructed SSS, but were not designed to collect large amounts of water runoff from heavy down fall and its subsequent events. Increase of snowmelt and rainfall areas served by SSS within a municipality have s separate storm sewer system to convey and collect the rain off. The untreated or partially treated discharges from SSS are known as the SSOs which are caused by various factors. These factors include defects of the sewer, excessive storm water and lapses in the sewer system. It can also be caused by inadequate sewer design and lack maintenance.
Impact of CSO
Combined sewer systems were common in the late 19th century before strategies of centralizing waste water treatment became a solution which led to the protection of public health especially to the in urban areas. After the centralization of water waste treatment, CSO usually occurs in old sewage systems where storm and sanitary sewers are combined resulting from heavy down fall. Some CSO discharge every time whenever there is rainfall and others happen on rare occasions. Over flow duration and frequency varies from system to system. The water capacity leads to high capacity of sewage treatment plants. However in many cities, Cinnanti is attempting to find the best ways of meeting federal and state requirements on CSOs. Such efforts have worked through the following three efforts for coming up with a solution.The separation of the sewer flows is an expensive but rewarding project. This is done by building other sanitary sewers using the already existing sewer as a storm sewer.
Secondly, is to increase the capacity and ability of the treatment plant so that they can hold higher rate of water flows. The third solution deals with the storage capacity within the system. This is an effort to equalize the flow of the treatment facility through in-pipe storage. Some, cities have managed to built large tunnels to hold and capture sewage for later treatment while others have used vortex regulators to back up and restrict the flow or the existing sewers.The CSO contains highly dilutes sewage with bacteria that causes illness. The bacteria cause water degradation in quality though temporally. This therefore means that activities such as swimming, canoeing and fishing which involve water immersion should be avoided in such water bodies. The activities should also not be recommended in such water bodies after heavy rainfall (Gregorski ,2010)During heavy storms the CSO discharges causes serious problems, due to water pollution in the communities.
Water pollutants contain pathogens, toxic chemicals and debris.In Chicago, and the surrounding communities, the metropolises serves sewer network that carries both storm water and the sewage. Majority of the porous ground covers an appropriate of three hundred and seventy five squire miles that has a population of over three million people. It has been covered with buildings, pavements and streets, and storm water runoff combines into several sewages leading to excesses in their capacity. The danger with this is that the excess over flow by pass the treatment plant. The mixture of rain water and d raw sewage spills directly to streams and rivers in the city. The combined CFSO results into sewage water and air pollution in addition to flooding of the water ways. In the season of heavy rains, the over loaded water with raw sewage flows into the MichiganLake which is the source of drinking water.
Efforts of mitigating CSO in the United States
Over seven hundred and fifty communities are served with combined sewers systems in the United Sates. The Environment Protection Agency (EPA) implemented a policy in 1994 that required all municipalities to take effective efforts of eliminating and reducing CSO related pollution problems. This act was later amended in 2000 which required all municipalities to comply with the policy. By 205 approximately one billion US dollars was put aside for the creation of CSO investment tat was to worth $2.4 billion. This has led to the reduction of untreated discharge of more than twenty billion gallons each year. This investment has yielded into CSO reduction by the reduction of CSO storage and treatment facility, numerous sewage operation and waster water treatment. The improvement of water treatment plant has continued to be constructed every year by regional and local government.
Other communities and municipalities are in progress of implementing strategies that address CSO. For example, WashingtonDC is separating its sewers in small neighborhoods which have cost $11 million. These projects also include the improvement of drinking water.The retention of treatment basins in large concrete tank has also been used in various municipalities in the country they are underground structures that are high in storage and treatment of up to 120 million gallon of combined sewage.The electronic Discharge v Monitoring Report- eDMR is system used by Illinois in Reporting NPDES. It is an eCommerce technology tat was developed so that NPDES Permittee with the internet and the computer in any form of connectivity.
The technology ensures high quality data that enables the ability to perform high quality assurance checks on data to be submitted and signed in. this leads to the reduction of paper work, convenient form application and improved speed and accuracy in reporting.The City of Metropolitan has called for feedbacks and comments from the public development of CSO Public Notification Plan. ( Metropolice illlinois2007) The metropolis considers government organizations, civic groups and recreation groups and the general citizens with the responsibility and interest for the condition of Ohio River. The groups include boaters, commercial fishers, recreation groups and environmental organizations like USEPO, ORSANCO and IEPA.
Way forward for Combined Sewer Discharge in America
The officials of water industry have to consider Vortex valves as a technology for outlet flow of control systems. These units can be implemented in water management systems so as to reduce aerate discharge, erosion and equalize the flow. The vortex valves are ideal for preventing erosion (Andoh, & Neil, 2008). The valve is also important for aerating water. They come handy in depleting dissolved oxygen levels of waters that has been stored in the underground of streams and rivers without first improving the oxygen quality of the water which may affect human beings and animal around it. Vortex valves are also used to alleviate over flow problems in combined sewer and sanitary sewer conveyance systems. This therefore shows that these outdated systems require more technological improvements so as to prevent the dangers it has on the environment, human beings, and the animals (Gregorski ,2010)
The development of improved technologies and strategies of preventing over flows of combined sewer system is essential for the prevention of pollutants that affect the public. The use of Vortex valves is the way forward for many communities in the United Sates and Canada which are currently struggling with outmoded systems that carry storm water and sewage. To prevent effects of pollution which affects human and animal health, the US Environment Protection Agency has mandated that all communities having CSO to minimize or prevent them. This can be done through the expansion of the capacity waste water treatment or either to separate the sewers.
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Gregorski , T(2010)Water keeper Alliance helps to shape storm water programs across the country
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