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GVL：Over the past 21 years, GVL keep putting its effort in sustainable practice and technical research on Sponge City, trying to integrate the technology with landscape in each practice. This award-winning project is located in the central lake and surrounding area of Feilaixia Water Conservancy Hub, in Qingyuan city, north of Guangdong. which was led by Lvqiu Jie, the design director of GVL, has successfully integrated the Sponge City technology with landscape design. More importantly, it provides a “low-cost, high-efficiency” solution to the domestic sewage discharge problem in areas with remote locations and lack of funds.
研究背景 Research Background
Feilaixia Sponge Park is located in the central lake area of Guangdong Water Conservancy Hub (hereinafter referred to as “hub”), which is remote with under-developed municipal infrastructure and without sewage treatment facilities around.
As a result, the sewage from the research zone, office and living area on the site have been only treated with basic secondary septic tanks, and directly discharged into the pond of the park. The water quality of the pond has deteriorated year by year, which does not even meet the requirement for agricultural irrigation prior to the works. Meanwhile, the renovation was restricted due to a shortage of funds, which result in serious damage to the environment and biodiversity of the pond and surroundings.
▼严峻的生活污水排放形势 Severe situation of domestic sewage discharge
▼生活污水的组成 Cause and composition of domestic sewage
▼生活污水带来的危害 Domestic sewage threatens human well-beings
▼地理位置偏远和资金缺乏导致基地的生活污水排放问题一直无法得到妥善解决 Domestic sewage treatment in remote area was restricted due to its location and shortage of funds.
Therefore, a low-cost and high-efficiency sewage treatment system is urgently needed to properly discharge the sewage, improve the surrounding environment, and enhance the water quality and restore the ecological system as well.
Moreover, users of the hub are seeking to a comfortable and ecological environment with low maintenance cost and high operational efficiency to solve both sewage treatment and stormwater management issues.
▼总平面图与建成后的卫星图 Overall masterplan and satellite image after completion
The project was completed in 2018 and has been in operation for three years. Now the quality of water has been gradually improved, and the plants and environment have been restored, which provides a pleasant working environment for the staff of the hub.
猜想与研究 Assumption and Research
Based on the research objective, we teamed up with South China University of Technology (SCUT) and made an assumption that will replace the high-cost traditional engineering methods and used landscape strategies with “low maintenance cost and high operational efficiency” to solve the sewage treatment problems. The project aims to address:
(1) What are the effective Low Impact Development (LID) facilities for sewage treatment? Can these approaches simultaneously act on the treatment of the surface water pollution caused by rainwater and domestic sewage?
(2) How to effectively combine different types and proportions of Low Impact Development (LID) facilities under low cost constraints to achieve the optimal purification performance and achieve the goal of “Low cost and High efficiency”?
Based on the questions above, we came up with three research plans:
1.Focus on Low Impact Development (LID) facilities, plants and substrates to build a low-cost and high-efficiency sewage treatment system.
2.Choose combinations in terms of construction cost, maintenance cost and the plant’s purification performance.
3.Establish a sustainable landscape system from the perspectives of aesthetics, education and social influence.
▼LID设施、土壤和基质的选择与组合方式是解决问题的关键 Combination of LID facilities, soil and substrates is the key to solve problems.
We collaborated with specialists in the fields of sewage treatment, phytology and water conservancy engineering, and built models through field study, adaptive modeling Storm Water Management Model (SWMM) and orthogonal experiments, to quantitatively analyze and compare the wastewater treatment strategies of different Low Impact Development (LID) facility combinations in terms of construction cost, maintenance cost, substrate and the plant’s purification performance. When the four types of LID facilities including constructed wetland, rainwater wetland, wet pond and artificial floating islands, account for 4.76%, 15.87%, 71.43% and 7.94% respectively, the sewage treatment strategy has the optimal efficiency on the site.
▼研究过程：植物的筛选与生长状况跟踪 TEST: Plant selection and tracking of their growth
▼研究过程：基质的筛选与跟踪 TEST: Substrates selection and tracking
▼研究过程：通过SWMM模拟分析潜流湿地、表流湿地、湿塘、生态浮床对污染物处理效率，叠加分析每个设施的建设与维护成本，所能作用的规模，以及使用寿命。METHOD: The runoff control rate, the removal rate of TSS (total suspended solids) and TP (total P) are simulated respectively on the SWMM platform, and the calculation of construction and maintenance costs are superimposed to determine the optimal combination mode to achieve Low-cost and High-efficiency.
▼研究过程：根据正交试验法则，将四个低影响开发设施作为组合因子，模拟出9种组合方式，在SWMM平台中分别模拟径流控制率，TSS和TP的去除率，并叠加建造及维护成本的计算，最终确定低成本高效能的最优组合方式。 METHOD: According to the principle of the orthogonal experiment, four LID facilities are used as combination factors, based on which nine types of combinations will be simulated. The runoff control rate, the removal rate of TSS (total suspended solids) and TP (total P) were simulated respectively on the SWMM platform, and the calculation of construction and maintenance costs are superimposed to determine the optimal combination mode to achieve Low-cost and High-efficiency.
▼研究结果：潜流湿地、表流湿地、湿塘、生态浮床4种低影响开发设施分别占比4.76%，15.87%，71.43%以及7.94%的时候，对于该基地而言，污水处理策略具有最优的效能。 Research Result: When the four LID facilities of constructed wetland, rainwater wetland, wet pond and artificial floating islands account for 4.76%, 15.87%, 71.43% and 7.94% respectively, the sewage treatment strategy has the optimal efficiency on the site.
▼建成后的基地景观更加趋于原生态，除了必要的维护，几乎不需要人为介入，这正符合我们对该场地的预期效果。After completion, the landscape here is in a natural state and runs effectively without any human intervention except necessary maintenance, which nicely achieves our expectation.
设计策略 Design Strategies
Based on the research conclusions, we first laid out two system on the site, respectively the sewage treatment system and the rainwater treatment system.
These two systems are complementary and coupled. Rainwater can enter the sewage system to participate in the purification of water quality, and after sewage treatment, it can be used as a supplementary water source into the rainwater management system. The two work together to build a healthy ecosystem.
▼建成后的全貌 Overall view
In order to maximize the capacity of LID facilities on the site, the research team proposes two innovative design strategies which match with site characteristics based on the result of the research.
1. To resolve the huge difference of elevation on site, the constructed wetland was designed as terraces. On the one hand, it resolves the height difference of 8 meters of the site, on the other hand, it maximizes the water body area, so as to maximize the decontamination efficiency, at the same time, it can also provide more potential for landscape opportunities.
▼台地形式的人工湿地水处理流动路径 Constructed wetland is designed as terraces for efficient water treatment
▼表流湿地承接来自潜流湿地的雨水和污水尾水进行二次净化 Secondary purification of waste water and rainwater from subsurface wetland
2. To increase the contact area between the constructed wetland and the sewage, we introduced a brand-new vertical layout for substrates instead of the traditional horizontal layout, which proved higher efficiency in decontamination.
▼创新的填料布局方式提升污水净化效率 A brand-new vertical layout for substrates is introduced to achieve higher efficiency in decontamination.
研究与设计落地 Implementation of the research and design
To improve the living environment and upgrade the recreational experience, we introduced some landscape and artistic renovation and design, including:
▼生态碎石渠内的碎石取自本地采石场,形成的景观效果与本地的水文风貌相互呼应 Gravel from local quarry used in ditch for both drainage and decoration purpose
▼利用建筑废弃材料制成的透水铺装补充吸纳两侧绿地产生的雨水径流 Permeable pavement made of recycle waste building materials collects runoff from the green land.
▼亲水栈桥与湿地相互呼应，带来舒适的游览体验 The boardwalk dialogues with the wetland and provides a comfortable sightseeing experience.
▼湿地内净化的雨水经过低堰步道跌入湿塘中 The purified rainwater in the wetland falls into the wet pond through the low weir trail
▼生态浮床 Artificial floating island
▼科普走廊：设计师根据海绵系统规划园区内的动线，完整地向社会人士、校园学生、专业同行展示了从收集传输到储存净化的雨水管理全过程，具有极佳的教育意义。Science popularization passage: a sponge system visiting tour route was carefully planned, showing the whole process of stormwater treatment to the visitors.
▼由多种乡土植物组合配置形成的景观花镜 A landscape flower border formed by a combination of a variety of native plants
The research project solved the sewage treatment problem of the site with a relatively low construction cost of CNY¥250/㎡, saving nearly 40% of cost compared to traditional engineering methods. At the same time, the original poor ecological sewage pond and its surrounding environment is transformed into a picturesque landscape garden and eco-friendly habitat. This research project demonstrates a “low-cost-high-efficiency” landscape strategy to solve the problem of sewage treatment in remote areas.
The project has been promoted as a water ecological technology demonstration area and has received visits and attention from all over the country. It plays a role in science popularization and helps to raise the public ecological awareness. More importantly, this research is highly replicable and provides a universal solution for areas suffering from sewage issues all over the world, helping to improve basic living conditions in undeveloped and remote areas.
Project name: Feilaixia Sponge Park
Landscape Design: GVL Group
Sponge city consultant: Department of Landscape Architecture, School of Architecture, South China University of Technology
Water treatment technology: Guangdong Research Institute of Water Resources and Hydropower
Construction: Guangzhou Huahui Landscape Engineering Co.,Ltd.
审稿编辑：任廷会 -Ashley Jen
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