Long history witnesses, Nanyang is a water city, green city, historical and cultural city. At the end of the last century, accompanied by the Chinese land reform and opening up the spring breeze, Nanyang urban scale rapid development, urban growth, urban residential population capacity, production, life aggravation of the city's operating load, far beyond the capacity of the urban infrastructure. Urban sewage can not be effectively collected, treatment, resulting in the river sewage flow, the White River turned black. In the 1990s, a rubber dam on the White River was built, water storage, the urban watershed area increased, the climate environment has been effectively improved, but the urban sewage treatment lagging behind, wantonly discharged into the river, the clear water becomes muddy, floating in the water dirt, overgrown weeds in the river, mosquitoes and insects breeding, pungent odor, the breeze gives a person a sense of suffocation. Some areas and sections of the river have been blocked and intercepted, and discharges and discharges have been banned, but it is difficult to achieve the purpose of treatment. Just like a city without public toilets, it is difficult to prohibit citizens from urinating and defecating at will. Relying on the upper reaches of the White River to release water to flush out the pollution, only a temporary solution, but also only the river surface of the temporary storage of dirt washed away, partially washed away, the residual dirt accumulated over time, the White River that has become a sewage river, cesspools, the urban river, not to mention. Flow, the accumulation of all sewage, rising temperatures, bad smell bursts, sewage dense places, suffocating. The old city is already a "sewage city", the new development of urban areas do not take effective measures to eradicate sewage discharge, if still so, will soon be a "new city" into a "dirty city". Effective management of sewage discharge, imminent. Nanjing Qinhuai River is a rich historical story, long prestigious city river, to Nanjing City, adding civilization, beauty, and is the sewage management is not good, from time to time due to excessive inflow of sewage, dead fish and shrimp overflowing the river, putrid smells emanating from all over the city, a big blow to the cityscape. We can not destroy the living environment for the production, life, not to mention the survival and harmful to others, future generations. Effective management of sewage discharge, but also the White River, but also Nanyang a clear, clean, green, elegant ecological environment, is the contemporary Nanyang people can not shirk the responsibility!
1 current situation of sewage discharge facilities
In the 1990s, the implementation of comprehensive improvement of the urban section of the White River, since the Wenliang River into the mouth of the White River in the downstream direction, the construction of a dedicated sewage discharge channel, the diameter of 1m or so of the round tube, to a certain extent, reduce the discharge of sewage to the White River, but the specifications are lower, the facilities are rudimentary, the discharge of a small amount of siltation is difficult to run for a few years after the damage, Clogging is serious, and now nearly scrapped, the river has become a sewage river, sewage flows into the White River, looking at the river surface floating dirt, deplore full of helplessness. Rapid development of urban areas along both sides of the White River, the production of newly developed urban areas, living sewage can not be effectively collected, in an out-of-control state, or open, or dark direct discharge into the White River. In the past two years, on the north bank of the river along the riverfront road is being built sewage channel, the use of less than 2 meters in diameter reinforced concrete round pipe, the scope of service is limited to the Wenliang River to the White River downstream area, the caliber is small, low discharge energy, only for the old city sewage used, it is difficult to solve the problem of discharge of the White River upstream of the new development of urban areas and the lack of dirt removal facilities, desilting, dredging difficulties, easy to block, loss of discharge capacity. Layout is not reasonable, construction methods are not proper, construction for more than two years, is still in the stage of attack, what to talk about to the upper reaches of the White River, the lower reaches of the extension ?
2 Successful Examples
Sewage discharge is an important part of the survival and development of the city, is a major part of the production of people in urban areas, life. Many cities in many countries have benefited from the effective implementation of sewage discharge, and many others have suffered greatly from poor discharge and treatment measures. Paris, France, the city, the underground 300km sewage channel, built 160 years ago, is still the world's typical urban construction projects, completed a world-class metropolis of sewage discharge, rainy season flooding tasks, hundreds of thousands of experts and scholars to visit the annual visit, the underground channel of the large, for the management and maintenance of the personnel, equipment into the operation, passage. Function of the perfect, in addition to sewage, flood discharge, can be laid pipe networks, cables, part of the section for tourists to enter the visit (in the 1970s, the domestic circulation of the handwritten copy of the French detective novels, there are perpetrators down the sewers to escape from the plot, the feeling was incredible, and occasionally have the opportunity to go to Paris, witnessed and realized). For many years, the Seine River and many other rivers in the city of Paris are still clear and smooth, there is no river pollution, flooding in the rainy season. Qingdao City, formerly the German Concession area, in the German occupation period, the construction of underground sewage channels, Qingdao citizens said: "those channels are very large, can drive a car in". This shows the scale of the project. In recent years, a number of cities, such as: Guangzhou, Wuhan, Hangzhou, Nanchang and other cities, heavy rainfall season, there have been many urban flooding, underground building flooding, car floating, low-rise housing was flooded phenomenon. Analyze the reason, the urban discharge channel planning and design, construction management is seriously backward, discharge capacity is low or circulation is not guaranteed to. In contrast, Qingdao City, the former German Concession, it is the German construction of underground drainage channels play a role in the discharge of smooth, no sewage flow over the years, urban flooding phenomenon.
Treatment of urban sewage, eliminate urban flooding, effective measures are: the construction of urban underground river, the formation of discharge channels throughout the city network. Set of sewage collection, circulation, treatment, discharge (or reuse) and auxiliary urban flooding as one of the network system. Sewage disappears at ground level, realizing that sewage and river water go their separate ways without committing crimes against each other, creating a clean urban environment.
3 overall planning
Nanyang City, north of the Baihe River, there are several rivers and their tributaries such as the Yonghe River, Wenliang River, Meixi River and so on are densely populated with the Baihe River intertwined into a network. Along the river planning and construction of underground sewage channel (below the riverbed, shallow burial depth, construction difficulties), the river is intertwined, the basic conditions are good. Constructing the main channel along the White River, constructing the trunk channel along the inner river in the urban area, constructing the branch channel along the tributary of the inner river or part of the street, and the branch channel extends to each production and living area, all the channels along the river are constructed under the riverbed, and the original river is no longer responsible for the task of sewage discharge, and after clearing and treating the sewage, the embankment, the green belt, and the pedestrian passage are constructed, etc., and the existence of permanent buildings is prohibited in the range of 30-50 meters outside of the embankment, and everything is for the Green light for the construction of urban environment. After the treatment of the inner river from the upstream water source to draw fresh water into the city, restore the city of the river grass green water, sand and gravel to the bottom, fish and shrimp swimming, birds and flowers landscape. Urban sewage and storm water quantitative rainwater through the underground channel into the branch channel, trunk channel, the main channel, sewage treatment plant. South of Baihe River and the newly developed urban areas, the original river is sparse, fully along the existing river bed to build the discharge channel, while according to the development plan, the construction of a certain density of artificial river, draw fresh water into the city, and synchronize the construction of the underground sewage channel of the branch line, trunk line. According to the density of the size, according to the discharge needs, but also along the urban part of the road planning and deployment of underground channels, forming a network, throughout the new and old city. The main line, trunk line, part of the branch line, with sewage, drainage function at the same time, according to the needs of urban construction, laying pipe network (water supply, gas supply, heating), power grid (electricity, telecommunications and other cables, fiber-optic cables), integrated development, make full use of, and realize a multi-function. Crochet an above-ground river network, improve the urban environment; construction of an underground river network, sewage, flood relief, while regulating pipelines into the ground. Efforts to maintain the ecology of the river system, and solidly promote the rainwater, river water and sewage diversion and sewage, sewage treatment works to improve the level of support and protection of water environment infrastructure.
4 construction
Along the White River on both sides of the embankment side of the riverbed under the construction of the main line of the sewage channel, upstream to the planned urban boundary, downstream to the urban boundary outside to the sewage treatment plant. The main channel parallel to the center line of the White River construction, strict internal seepage, external seepage treatment, the two sides of the channel every interval of a certain distance to set up an interchange channel, to facilitate the regulation of the flow and a single hole out of service for maintenance and repair. A certain distance set up import and export, realize the management and maintenance of equipment, personnel in and out and sedimentation of dirt transportation. Each trunk channel into the main line at the entrance to set up a sedimentation tank, built solid floating material to remove the motorized gate, at any time to remove the accumulation of outward transportation, to ensure smooth and unimpeded. The main channel cross-section is set up as an inverted "pear" shape, the maximum inside diameter is not less than 6 meters, the upper section is semi-circular or rectangular, increasing the discharge volume at the peak of the discharge, the lower section is "V" shaped, the discharge volume is smaller to increase the flow rate, effectively reduce the precipitation, reduce siltation, and safeguard the discharge capacity. Discharge capacity. Inside the channel, there are pedestrian passages on one side or both sides to complete the management, maintenance and observation of the channel and the internal pipe network and power grid.
Built along the urban riverbed under the trunk channel, the new urban areas in the full use of the existing riverbed, the use of the newly opened artificial riverbed and part of the road to build an underground channel, the maximum inside diameter of not less than 4 meters, the shape of the cross-section such as the main channel, the internal setup and the main channel is similar to a certain distance from the set of people, machine entrances and exits, the branches flow into the trunk channel at the entrance to the set of sedimentation tanks and motorized gates, to reduce the flow of solids into the trunk channel. Into the trunk line channel.
Along the inner river tributaries under the riverbed or part of the road suitable area (green belt, pedestrian access, non-motorized road) underground, laying sewage channel branch, with a single side of not less than 3 meters of the rectangular channel or diameter of not less than 2 meters of pipe culvert based on the cross-section set up to ensure that people and machines to achieve effective cleanup of sewage, dredging. Downtown intersections underground, the construction of a single side of not less than 3 meters of rectangular channel, the realization of the sewage function at the same time, to ensure that the pipeline network, line network layout through the city to put an end to the daily digging trench, often broken road, underground pipeline network, line network randomly laid phenomenon. In a certain length of the branch line in a suitable location, set up people, machine import and export, in the rainwater collection area, set up automatic flow restriction or artificial motorized flow restriction rainwater inlet, to ensure that flooding in a timely manner during heavy rainstorms, to put an end to the emergence of waterlogging in the city.
The branch channel connects the branch sewage channel from each area of each street, each branch channel to not less than 1 meter pipe culvert is the main to ensure that the sewage discharge in the region, rainwater drainage, the entrance to set up sedimentation tanks, activity grille, prohibit the entry of solid flow, to ensure that the pipeline is smooth. The key control areas for sewage discharge, set up flow restriction and flow control devices to realize orderly management and quantitative discharge.
Based on the urban planning of industrial distribution, residential density and other elements, accurately calculate the maximum sewage flow, based on the region's geography, terrain and historical flood peak values, accurately determine the maximum flood flow. To determine the distribution density, structure size, and other data of the sewage channel on the basis of several times the production, life discharge extreme peak and the maximum value of auxiliary flood relief.
Construction of the control center, the main line, trunk line, branch line, all the implementation of video surveillance and dynamic monitoring of operational data, the entire system to achieve information management, at any time to observe the operational status of each place, at any time to detect the operation of the data of each point, timely delivery of water quality change information, the implementation of dynamic monitoring of the various parts of the sewage channel, the motorized grill, gates, pollution-clearing equipment, flow restriction devices, such as the realization of remote control.
The project is a systematic, perfect permanent project, to adopt the success of the model experience, learn from the lessons learned from a number of poor governance and victimization, make full use of modern technology, with forward thinking, meticulous planning, put into practice. Can not blindly follow, rashly, hastily.
5 construction
By the order of construction of the main line after the main line, branch line, each branch channel, the main line, main line, branch line new, each branch channel, can be based on the original sewage facilities, alteration, expansion, restoration and reconstruction of the main. From the downstream to the upstream, the first construction of the main line channel, in the main line to complete the section, the completion of the trunk line channel, the trunk line completed section, the completion of the branch line channel, the branch channel. Complete a section, put into use a section, and extend upstream in turn. Can also be based on the economic capacity of phases, segments, sub-regional completion. Until the entire sewage system construction in the planned urban area is put into use. Expansion of urban areas, can be constructed successively.
6 construction program
Based on the entire sewage system planning and geographic and geological characteristics of Nanyang urban area, to determine the reasonable implementation of the program, select the appropriate construction methods to reduce construction difficulties, reduce project costs. The main channel and trunk channel are built along the river, with shallow depth, and can be constructed by cover digging method and steel plate cofferdam once-formed construction method, or a combination of both. Along the city roads or streets of the underground trunk line channel, the depth of burial is deeper, the shield method of construction, once formed.
Cover digging method: typical urban tunnel construction method, according to the side wall forming, roof capping, external seepage treatment, hole formation, internal seepage treatment sequence. The intersections, entrances and exits, and other parts of the special treatment. Can be synchronized on a large scale.
Steel sheet pile cofferdam construction: first use the steel sheet pile cofferdam to close the construction area, clear excavation of the enclosed area, according to the design of the channel construction and seepage control treatment. The construction is simple and cheap, but the scale of synchronized construction is limited by the amount of steel sheet piles.
Shield method: take shield method construction, channel once formed, fast, but high degree of mechanization, requires continuous operation, can not be interrupted, the input is more concentrated, and auxiliary supporting operations to be carried out simultaneously. The construction environment, construction conditions have certain requirements.
7 construction funds
To improve the sewage system throughout the urban area, is a huge, long-term project, is an important part of urban construction, is beneficial to today's and future generations of permanent projects. In a planning in place, the program is perfect on the basis of a planned, step-by-step implementation, according to the first after the main, the first after the order of tightening the slow, phased, staged completion. How much money is planned to be invested each year, how many projects to be completed, to "complete as soon as possible, early commissioning" as the goal of a huge project phased, segmented decomposition, turning big into small, gradual completion, in order to reduce the difficulty of the huge sums of money required to ensure that the construction process is continuous and efficient.
Funding sources:
1) as an important part of the city's construction, the government according to the project implementation plan, phased injection of part of the construction funds; 2) as a public welfare project for urban development, call for people from all walks of life in the city to donate enthusiastically from the community to absorb part of the funds; 3) according to the city's various enterprises, units, the residents of the ability to afford to pay a certain amount of money in the current cost of water in the building. Funds. After the system is put into use to reduce the funds used in advance; 4) the project is a long-term operation of the business project, construction funds can be borrowed from social and financial institutions, into operation, the charges to repay the loan.
8 Operation and Management
The whole system adopts market-oriented operation mode and independent accounting.
Operating income: sewage discharge treatment and water supply, water organic combination of production, living water, qualitative, according to the amount of sewage discharge treatment fees, according to the "who uses water, who bear the cost" principle, in the water segment of the discharge treatment fee. According to the nature of water use, discharge of water pollution to determine the base unit price of sewage discharge costs, requiring "first treatment, then discharge"; according to the amount of segment billing, the implementation of the ladder unit price, promote water conservation, the implementation of the "large amount of high price" billing method; along the underground sewage channel The pipeline network and power grid laid along the underground sewage channel, etc., and the relevant departments will bear a certain amount of fees for the use of the channel. Expenses: investment in infrastructure; maintenance of access facilities; later renovation and expansion costs; operation and management costs. The whole operation process is subject to government supervision and social supervision to ensure benign operation and effective operation, and to achieve the purpose of long-term service to the community and permanent benefit to the public.
This is a system of urban construction infrastructure projects, is an effective measure to solve the problem of urban environmental water pollution. The completion of the sewage treatment system, not only for the benefit of today, but also in a few decades, hundreds of years, and even hundreds of years later still benefit the people. Historical merit, far more than a building, a road, a square more favorable credit to a city and survive here for generations. Nanyang is in the transformation of the old city, the new city development of the rapid development of the rapid development period, the transformation of the old city, improve the sewage facilities, imminent, the development of the new city, the construction of sewage channels should be placed in the first place in the city, in favor of the construction and the improvement of ancillary facilities. After the completion of the new city, completely a beautiful modern city, an ecological health, elegant environment of the new Wancheng.
References
[1]Dai Yicheng. Building Green Cities: Sewage Management Design Anhui People's Publishing House, 2010.
[2]European Environment Agency. Guidelines for urban wastewater management [M]. China Environmental Science Publishing House, 2000.
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