Water pollution and the aggravation of flood issues
Water Pollution & Aggravation of Flooding
Records dating from 1962 show that swimming was banned in the lower streams of Hangang-daegyo while deformed fish with crooked spines were reported, testifying to the severe water pollution in the Han River which Seoul, with a population approaching 3 million, was facing. In a 1963 survey, BOD values reached 241mg/L in Cheonggyecheon and 124mg/L in Jungnangcheon. In addition, the seasonal rains typical of the Korean climate were contributing to frequent flooding.
A need for sewage treatment in Seoul was further highlighted as the 1960s saw the beginning of an explosive population influx, and industrialization went into full swing in the 1970s. Modernized sewerage spread throughout Europe after the mid-19th century, as the dumping of human waste into streams along with other causes led to urban problems such as raging cholera epidemics; while Seoul did not experience the same problems, concerns nevertheless arose regarding similar risks.
Seoul's sewer system back then was rather incomplete, inclined towards flood-prevention measures such as rainwater exclusion. Under the circumstances, improvement of water quality in the Han River was prioritized, and large-capacity sewage treatment plants were constructed in a short period of time.
In Western Europe, sewers were first constructed to allow the complete discharge of sewage into streams, with sewage treatment plants built thereafter. Japan, launching its sewerage plans after Europe, reflected on its predecessor and simultaneously installed sewers and constructed sewage treatment plants. For its part, Seoul had sewage treatment plants built before an adequate sewer system was in place; therefore, the faulty wastewater inflow into those treatment plants meant that domestic sewage could not be sufficiently treated. Only after the entire sewerage system was developed, including sewer installation, did the city see significant improvements.
Because Korea traditionally used human waste as fertilizer, the pollution of rivers and the living environment caused by the dumping of human waste was relatively less intense.
Water quality of the Han River had become an urgent problem as the 1986 Asian Games and the 1988 Summer Olympics approached.
The construction of sewage treatment facilities and sewers
Expansion of sewage treatment facilities and improved eco-friendliness
The first sewage treatment plant: the city at 3 million in population
Cheonggyecheon Sewage Treatment Plant (currently the Jungnang Water Reclamation Center, Plant No.1), with a capacity of 150,000 m3/day, was capable of processing domestic sewage generated by 1.3 million people in the 5,600ha Cheonggyecheon watershed area. The wastewater, with an average BOD of 330mg/L reached 19mg/L or less after treatment and was discharged into Jungnangcheon, before flowing into the Han River's mainstream.
The next facility to be constructed was Jungnangcheon Sewage Treatment Plant, for which ground was broken in 1975. Financed with KRW 4 billion in loans from the UK bank, Gradley Brandt, and KRW 6.2 billion in domestic loans, the budget totaled KRW 10.2 billion for a plant with a treatment capacity amounting to 210,000 ㎥/day. Unlike Cheonggyecheon Sewage Treatment Plant, the new plant featured a self-generating capacity of 1,400kW, 60 percent of its required electrical power, using gases produced during the treatment process.
Expansion of sewage treatment facilities
The Han River Development Project led to another series of comprehensive sewerage development projects. Under the agenda for an advanced capital and in preparation for the 1986 Asian Games and 1988 Summer Olympics in Seoul, the project had as its goal a comprehensive and multi-purpose development of the Han River. After launching in September 1982, the project involved 11 domestic construction companies and a total budget of KRW 413.3 billion.
The Han River Development Project was completed in September 1986. The urgency of conserving Han River water, increasingly recognized along the course of the project, resulted in establishment of the Sewer Maintenance Master Plan and construction of additional sewage treatment plants.
Measures were taken against rapid population growth and industrial development-induced water pollution into the Han River and bodies of water where discharge occurs such as Jungnangcheon and Tancheon. The Sewer Maintenance Master Plan devised in 1984, and the 1992 amendment, applied to the entire area of Seoul and included an objective for total sewage coverage by the year 2001.
In order for these plans to be realized, Seoul was divided into four treatment areas around the time of the 1988 Summer Olympics. Biological secondary treatment was assigned to plants corresponding to Jungnang and Tancheon areas, located upstream, and primary treatment was assigned to Gayang (currently Seonam Water Reclamation Center) and Nanji treatment plants, thereby truly bringing the city into the age of modern sewage treatment. Consistent facility expansion afterwards resulted in a total capacity of 3.71 million ㎥/day in December 1995 corresponding to 73 percent of total sewage quantity, and through another expansion initiated in 1998 aiming for complete sewage treatment, a capacity of 5.81 million ㎥/day was realized.
Greening of sewage treatment facilities
By covering the upper part of the water reclamation centers and turning those spaces into eco-friendly parks, the local population has been provided with resident-friendly rest and relaxation areas.
Improvement of sewers
Combined sewer system
Eighty-six percent of Seoul is serviced by combined sewers. Construction of such facilities in Seoul was initially planned for rapid exclusion of stormwater to prevent urban flooding, rather than the provision of infrastructure for the city's future development; therefore, sewer maintenance in frequently-flooded lowlands and areas with faulty drainage was a priority.
In addition, deterioration of the sewers resulted in problems such as damage and faulty connections, which in turn led to excessive inflow of groundwater, rainfall, river water, tap water and water from unidentified sources. Due to the inflow of stormwater, groundwater and such, along with the quotidian sewage, the total inflow reaching treatment plants amounted to 5.09 million ㎥/day by 1995, overloading the total processable facility capacity of 3.71 million m3/day. Sewage exceeding facility capacity underwent only primary treatment and bypassed secondary treatment plants, inevitably being discharged with water undergoing the full treatment process and leading to serious water pollution issues in the areas of discharge.
Sewer maintenance for prevention of flooding
A smart sewerage system using advanced information technology
Achievements of sewerage improvement
Seoul has currently achieved 100 percent connection of its population to the sewerage system. Total treatment capacity, originally 5.81 million ㎥/day, had reduced to 4.98 million ㎥/day by the end of 2013 after conversion to advanced treatment facilities with higher efficiency in nitrogen and phosphorus treatment. Total sewer length remains stable at 10,487 km. Introduction of advanced sewage treatment for nitrogen and phosphorus removal in 1996 has further improved water quality of the Han River; midstream and downstream BOD has been reduced to as low as 3mg/L or less, which makes swimming possible.
Improvement of water quality in tributaries
Water quality improvement in Jungnangcheon
Improvement of water quality in Tancheon
Even after 100 percent sewerage connectivity in 1998, the water in Tancheon remained quite contaminated, with BOD values exceeding 20mg/L. As the area upstream of Tancheon water system, such as Seongnam, expanded its facility capacity and introduced advanced sewage treatment facilities, and advanced treatment was introduced in 2011 to Tancheon Water Reclamation Center, the water quality considerably improved, and BOD is a stable 10mg/L or less.
Comprehensive efforts to reduce flood damage during localized heavy rains
In addition to sewer maintenance, stormwater-overflow-reducing facilities to facilitate the exclusion of flood discharge and disaster-preventing rainwater detention facilities which can serve as temporary storage for flood discharge have been installed. Construction standards for flood-vulnerable areas make it mandatory to install stormwater reservoirs for seepage water, to secure the flooding depth of buildings and to secure anti-flooding facilities for underground construction. Comprehensive flood countermeasures are being put in place, including the relocation of urban watersheds, inducing the practice of water-resistant construction, expansion of detention facilities, assigning disaster prevention functions to public facilities (such as parks and greenery, roads, schools, civil offices), improving ground coverage through reduced impermeability and supply of disaster prevention equipment (e.g. flood barriers, backflow prevention equipment).
Communication channels that provide citizens with disaster-related information include general broadcasting systems, local announcements, social network services, billboards, and such; these are elaborated through enhanced optional location-based notification services and the establishment of situation phases for civil action and evacuation. Citizen-participatory safety management involving smart information and communication technologies and community mapping is encouraged. Establishment of a citizen-led disaster prevention system including a real-time citizen reporting system and counter-flood systems in the private sector are also underway. Long-term measures such as the introduction of rainfall radar will allow the identification and forecasting of various weather phenomena, making it possible to prevent and respond to natural disasters. A flood prediction map according to precipitation is another active disaster control measure.
Organization of the sewerage management system
The Sewerage Act, enacted in 1966, provided a legal basis for sewer administration. As sewerage-related tasks increased dramatically, the Sewerage Division under the Construction Management Bureau underwent a large-scale reorganization into the newly-established Sewerage Administration Division, consolidated with the Water Management Division and raised to the status of Sewage Management Bureau in 1976. In addition, the 1982 Han River Development Project aimed for enhanced use of the Han River and its improved water quality. The Ordinance on Sewerage Use announced in 1983 laid the legal basis for the collection of public sewerage user fees. The four sewage treatment plants currently in use include Jungnang, Nanji, Tancheon and Seonam Water Reclamation Centers. “Sewage treatment plants” underwent official name changes to “water reclamation centers” in 2006, in an effort to rebrand the plants away from sounding like locally-undesirable facilities to needed water production facilities. Sewage treatment facilities were under direct municipal operation of the Seoul city government until the IMF financial crisis in 1997 led to a general restructuring of the government and the consequent restructuring of organizations affiliated with the city in 1999, resulting in a decision to gradually privatize sewage treatment plants. The Government Organization Act and the Act on Public-Private Partnerships in Infrastructure provided the legal grounds for such moves. As part of its restructuring efforts, the Seoul Metropolitan Government has been holding discussions led by the Administrative Reform Committee and the Administrative Reform Working Committee on the reorganization of affiliated agencies, including the treatment plants, since 1998. Of the four water reclamation centers, Tancheon and Seonam were outsourced in 2000 and 2001, respectively.
The decision to outsource Nanji Water Reclamation Center, based on the 2008 reorganization plan for the Establishment of Organizations with Efficiency and Competitiveness, which put emphasis on the active contracting-out of outsourceable facilities and efficiency of organizational management, eventually foundered. Consequently, Nanji and Jungnang were left under direct management and partial outsourcing contracts. In order to secure the financial resources for sewerage management, sewerage user fees have been collected since 1984 according to the “causer pays” principle. The administrative organization supervising Seoul's sewerage facilities is led by the Water Quality Management Bureau under the Urban Safety Office, which directs a total of four divisions (each consisting of five or seven teams): Water Quality Management Division, Sewerage Treatment Planning Division, Sewerage Treatment Facilities Division and Stream Management Division. Of these, the Sewerage Treatment Planning Division and Sewerage Treatment Facilities Division are directly related to sewer management. Two of the four water reclamation centers, Jungnang and Nanji, are under direct municipal management with the exception of outsourced sludge treatment facilities, while Tancheon and Seonam Water Reclamation Centers are completely outsourced.
Article 6, Paragraph 3 of the Government Organization Act states that an administrative agency may entrust its competent matters involving surveys, inspections, verifications, management, etc., that are not directly related to the rights and duties of citizens, to a juristic person that is not a local government, an organization, or its organs or other related individuals.
The 1994 Act on Public-Private Partnerships in Infrastructure provides legal grounds for participation by the private sector in environmental infrastructure; the Ministry of Environment proposed various forms of installation and management of environmental infrastructure by implementing the Environmental Infrastructure Privatization Manual in 1997, thereby enabling actual participation by the private sector.
Significant precipitation differences throughout the year due to characteristics of the rainy season
In response to this, the city is managing streams and watersheds in an integrated manner to process nonpoint pollution and overflow discharged into streams during rainfall. The overflow water quality standard as prescribed by the Sewerage Act, under 40mg/L, applies to the administrative standard for CSOs in storm outfalls alongside streams; CSOs in excess of 40mg/L are stored and processed. In addition, routine processes such as sewer pipeline dredging, rainwater management, water cleaning of roads and measures to reduce unidentified water are carried out in watersheds to reduce CSO emission.
Lack of awareness and faulty construction of separate sewer systems
Insufficient financial support for the sewerage system
Conclusions and implications
There are 36 waterways running in or through the city of Seoul as defined by law, including the Han and five other rivers and an assortment of streams; water quality in these streams is maintained with the objective of enabling swimming, in order to provide citizens with ample water resources. Through past water quality management achievements, including a 100 percent sewerage-connected population and reduced water pollution, the pollution load flowing into rivers has diminished, and water quality has greatly improved. The functions of a sewerage system include flood prevention via urban rainwater exclusion, sewage carrying, improvement of the living environment with flush toilets, water preservation in public bodies of water such as rivers, lakes and seas as well as protecting health and sanitation. As the sewerage system is an indispensable part of infrastructure in relation to people's environmental rights, the necessity for proper maintenance is ever increasing. When considering the characteristics of runoff in Seoul, as an urban center, a dominance of impermeable area directly connected to the drainage system can be noticed, which, along with changes in rainfall patterns, influences the planning of urban drainage facilities. The close relationship sewage issues have to urban planning and land use must be taken into account. Long-term variations in rainfall patterns due to macroscopic changes such as climate change must also be prepared against in advance, to prevent disasters such as flooding. With the objective of creating a comfortable and safe living environment, Seoul is proposing the next step in construction of a future-oriented sewerage system which features advanced technology and promotes citizen-friendliness, ecological preservation, security and resource recycling.