Tangshan Nanhu Eco-city Central Park

The site was an extremely large brownfield, full of contaminated waste and sewage, as well as areas of geological subsidence. Notably, the entire southern portion of the site lacked geotechnical stability. One of the key design challenges was to address the settling land and determine a way to use this part of the site in a viable way which would complement the rest of the park.

Solution

The design responded to the site’s varying environmental conditions by proposing very different uses and aesthetic characters north and south of the main dividing road. North of Tangxu Road, the park is geologically stable and thus designed for active recreational uses, with features including gardens, the reclaimed rubbish hill, plazas and trails. The area south of Tangxu Road is designed to be a natural reserve, retaining its natural vegetation and landform with few interventions. This part of the park includes cedar grasslands, wetlands and other landscapes native to the region. The settling land and shorelines within this area were stabilized primarily with materials found onsite, such as rocks and wood posts made from dead trees.

• More than 620,000 trees and shrubs of about 100 species are planted in the park, creating various wildlife habitats including woodland, bosque, grassland, and wetland.
• 450 metric tons of rubbish in Nanhu area were reclaimed and used to create a 50-meter high hill, offering 130,000 square meters of green space. The hill was sealed, covered by soil and planted with trees. It provides scenic views, and various recreational opportunities, such as walking, hiking and picnicking. A waste gas collection system in the rubbish hill collects and burns the gas generated by the rubbish, preventing it from being emitted into atmosphere.
• Two lakes, as well as a series of smaller water features, offer scenic and recreational value. These lakes fill former subsidence basins and are recharged without potable water. The south lake receives about 80,000 cubic meters of reclaimed water daily, after it is discharged by a water treatment plant into a series of constructed wetlands. The north lake is recharged by 20,000 cubic meters of groundwater, which is obtained daily from the coal mining site to the north of the park. The two lakes are the water source for landscape irrigation.

• Boat docks and extensive boardwalks along the lakeshores bring people to the water.

• Islands in the center of each lake are constructed with reclaimed coal ash, as is the scenic peninsula on the north side of the southern lake.
• An embankment made of gabions and the bundled trunks and branches of 133,820 dead trees stabilizes the lakeshore.
• Recreational spaces within the park include the hill, a central island, botanical garden and main plaza.

• The park’s lakes need to be recharged regularly to maintain the water level. Reclaimed water from a nearby waste water treatment plant is used to do this, supplying 29.2 million cubic meters (7.7 billion gallons) annually. If an equivalent amount of potable water were used instead, the cost would be $15.4 million per year.
• About 6 million cubic meters of coal ash from the site was reused to form foundations and make bricks used in park construction. If coal ash had not been reused, earth would have been purchased instead, which would have cost about $47.2 million.
• The trunks of 133,820 dead trees were used to form an embankment structure along the lakeshore to prevent shoreline erosion. If an equivalent amount of timber had to be purchased, the cost would be $369,000.

• Dormant willow posts (large willow cuttings) were installed along the lakeshore in order to stabilize the banks, The following spring, the willow posts sprouted as expected, indicating that the method was successful. In the long-run, the willows will not only stabilize the banks, but will also provide shade and habitat.

Project Team

Client: Tangshan Nanhu Eco-city Management Committee
Landscape Planner and Designer: Beijing Tsinghua Urban Planning & Design Institute
Cooperator: Tangshan Urban and Rural Planning Bureau

Role of the Landscape Architect

As the leaders of the design team, landscape architects played a key role in design and planning and organized team members to form an efficient working group. The team included experts in geology, civil engineering, ecology, horticulture, hydrology, architecture, and municipal planning.