“Sewage” fish farming, low-carbon design, harmonious coexistence————the art of pumped storage engineering in the mountains

"The 40 or so young fish we released three years ago have now multiplied into thousands." On June 5, World Environment Day, Zhang Bo excitedly introduced the changes in the ecological reservoir of the Qingyuan Pumped Storage Power Station in Liaoning Province. "In the beginning, the young fish were only 10 centimeters long, but now there are many fish that are 30 centimeters long."

Zhang Bo is the environmental protection specialist of the Qingyuan Pumped Storage Power Station EPC General Contracting Project Management Department (hereinafter referred to as the Qingyuan Pumped Storage EPC General Contracting Department). The ecological reservoir he mentioned is mainly used to store the treated water from the domestic sewage treatment station in the lower reservoir camp. These treated "sewage" have now formed a landscape of big fish jumping and small fish gathering in groups, becoming a "back garden" for project employees to relax in their spare time and take a walk after dinner.

This is a microcosm of the Qingyuan Pumped Storage EPC General Contracting Department's implementation of the concept of "Green water and green mountains are gold and silver mountains" and its efforts to create a "mountain and water project".

"Zero discharge" of sewage and wastewater, full utilization of reclaimed water

The Qingyuan Pumped Storage Power Station (hereinafter referred to as "Qingyuan Pumped Storage"), which is constructed by the EPC general contracting consortium led by China Power Construction Group Beijing Survey and Design Institute Co., Ltd. (hereinafter referred to as "Beijing Institute"), is located in Beisanjia Town, Qingyuan Manchu Autonomous County, Fushun City, Liaoning Province. It is the largest pumped storage power station in Northeast China, a key project during the "13th Five-Year Plan" period of the country, and one of the 139 major projects in the new round of national revitalization of the old industrial base in Northeast China. This is also the first million-kilowatt EPC general contracting pumped storage construction pilot project in China that includes a complete industrial chain of design, construction, and procurement.

This pilot project, which has attracted much attention from the industry and is led by the designer and managed by the EPC project, has been guided by the concept of "promoting harmonious coexistence between man and nature" from design to construction.

For the sewage and wastewater generated during construction and life, Beijing Institute carried out special design, and Qingyuan Pumped Storage EPC General Contracting Department organized the construction of 1 sand and gravel processing wastewater treatment system, 2 domestic sewage treatment systems, 4 concrete mixing wastewater treatment systems, and 4 cavern wastewater treatment systems. All treated reclaimed water is reused in production, sprinkling dust reduction, greening, etc., to ensure "zero discharge" of sewage and wastewater and full utilization of reclaimed water.

"The ecological reservoir was specially designed by Beijing Institute and constructed by Qingyuan Pumped Storage EPC General Contracting Department. It was built and put into use in 2020 simultaneously with the domestic sewage treatment station of Xia Reservoir Camp." Zhang Bo said that the domestic sewage treatment station of Xia Reservoir Camp is an underground integrated treatment equipment using MBR method. The treated water is clear and odorless, which can meet the growth requirements of fish. The treated water is used for sprinkling dust and greening in spring, summer and autumn, and is temporarily stored in the pool in winter without being discharged.

“Zero discharge” of sewage and wastewater also benefits from the design-led EPC project management, which is more conducive to giving full play to the design technology advantages and deepening the application of advanced technologies.

"The flushing of aggregates in the construction of hydropower projects will generate a large amount of wastewater. The wastewater from the sand and gravel processing system has extremely high suspended matter and huge fluctuations in water quality. The sediment is very easy to compact during the operation of the treatment system, causing system blockage and even equipment damage." Cui Xiaohong, head of the environmental protection department of the Qingyuan Pumped Storage Design Project Department, gave an example. The design team pioneered a new process of directly using the plate and frame filter press as the core treatment equipment of the system, which reduced two treatment units and a large number of ancillary equipment compared to the conventional treatment process, helping the sand and gravel processing wastewater treatment system to operate stably. This technology has been successfully applied to the Qingyuan Pumped Storage.

Reduce large-scale excavation and do a good job in ecological restoration

“A good project should not only play its functional role, but also avoid causing damage to the environment, carry out ecological restoration, and make the project harmonious with nature and friendly to people.” Yao Baoyong, general manager of Qingyuan Pumped Storage EPC General Contracting Department, has fully implemented this concept of engineering construction in Qingyuan Pumped Storage.

According to reports, one of the major advantages of design-led EPC project management is that it is conducive to resource integration from the source. During the construction process, the dam engineering professionals dynamically grasp the balance of earthwork, the geological professionals comprehensively review the weathering of the dam materials, intelligently guide the on-site construction, and make full and flexible use of the building excavation materials and cave excavation materials for filling different sections of the dam, reducing the excavation of the material field, saving investment and reducing waste on the premise of meeting the needs of the project.

Zhang Jianfu, project manager of the Qingyuan Pumped Storage Design Project Department, gave an example, saying that in order to maximize the utilization rate of excavated materials in dam filling and reduce waste, the permeability coefficient of some locations in the rockfill area downstream of the dam was fine-tuned based on the actual situation on site after technical demonstration.

Since entering the site in July 2017, the Qingyuan Pumped Storage EPC General Contracting Department has considered environmental protection as an important part of construction management, and incorporated it into the project work objectives along with safety, quality, and construction period benefits. To this end, the slope behind the anti-violation platform in the construction area was also used as a "test field" for water conservation and greening.

The slope behind the anti-illegal platform in the construction area is supported by grid beams. Considering that the Qingyuan Pumped Storage Battery is located in a cold area, the Qingyuan Pumped Storage Battery EPC General Contracting Department adopts cold-resistant and drought-resistant grass planting methods for support in the grid beams. The vegetation grows well and successfully reproduces by seed, which plays a good role in support and greening, and also becomes a green landscape in the construction area.

Clear water "aesthetics" integrated into nature

There are many examples like the grid beam where cultural and natural landscapes complement each other in Qingyuan Pumped Storage.

"The gatehouse at the inlet and outlet of the lower reservoir is a case in point." Zhang Jianfu said that the gatehouse is cast with plain concrete, which can achieve a mirror effect and does not require additional decoration materials. From a distance, the building itself does not appear abrupt in the mountains and blends seamlessly with the surrounding environment. Moreover, this material is time-tested and will increase the sense of history as time goes by, further highlighting the "original beauty" of the hydropower project.

In order to use plain concrete for the gate tower, the Qingyuan Pumped Storage EPC General Contracting Department overturned the previous concrete frame structure design. Zhang Jianfu explained that in the frame structure design, the beams and columns were built with filler walls, and the facade needed to be renovated after the construction was completed. After changing to a shear wall structure, the entire wall surface can be poured with plain concrete.

In order to use plain concrete, the original design plans for the dam top structure, power plant, main transformer room, switch station and other parts were also overturned. The most typical example is that Xing Shanshan, the person in charge of dam engineering at the Qingyuan Pumped Storage Design Project Department, had all three designs for the lower reservoir dam top railings overturned. However, when she saw the final design version of the plain concrete railings selected by the Qingyuan Pumped Storage EPC General Contracting Department, she still sighed and had to admit defeat.

"Qingyuan Pumped Storage Project adopts low-carbon design and construction of fair-faced concrete on a large scale, achieving the effect of fair-faced concrete requiring no decoration, striving to show the majestic, magnificent and natural beauty of hydropower projects, and focusing on creating high-quality projects." Yao Baoyong explained that the natural surface of fair-faced concrete as a building decoration effect is a new fashion and style in architectural art. It embodies the concept of modern people pursuing and returning to nature.

"The simple and natural beauty of fair-faced concrete can be seen everywhere in Qingyuan Pumped Storage. The craftsman spirit of Qingyuan Pumped Storage people who strive for excellence is also integrated into the fine craftsmanship." Yao Baoyong introduced that the large-scale use of fair-faced concrete design and construction has become a shining business card of Qingyuan Pumped Storage, and has also been highly praised by the construction unit and industry inspectors at all levels.

The construction of buildings cast in plain concrete indirectly achieved the poetic practice of "green water and green mountains, 'clear water' aesthetics" of Qingyuan Pumped Storage, which also benefited from the advantages of design-led EPC project management. Zhang Jianfu said that under the design-led EPC model, the design pays more attention to creating project highlights, is more active in promoting harmony between man and nature, continuously and proactively improves design quality, and specializes in engineering visual environment design.

Yao Baoyong has his own understanding of this: from the early stage of planning, we must improve the design concept, combine top-level design safety with ecological restoration functions, fully consider the artistry of ecology and engineering, and use low-carbon design. Only such a "landscape project" can make the background of green waters and green mountains brighter.

The lower reservoir of Qingyuan Pumped Storage Power Station is storing water (Source: Fushun News Network)