China's first sponge car depot put into use

With a subway train driving out of the parking lot of the Nanning Xinxu depot on June 3, the first sponge car depot in China was officially launched.

The sponge depot of Metro Line 3 is located on the east side of the beltway in the Xinxu area of Nanning High-tech Zone and on the west side of Xinji Road. It covers an area of about 491 mu (32.73 hectares) and is mainly responsible for the maintenance of subway vehicles on Line 3 and logistics.

According to the contractor, the sponge depot has six low-elevation greenbelts, seven rain gardens, more than 600 meters of grassed swales, more than 12,000 square meters of permeable bricks, and more than 820 trees of various types. These three-dimensional sponge facilities can ensure more than 9,000 cubic meters of sewage are purified every month.

The main body of the sponge depot is a permeation pond with a volume of more than 7,000 cubic meters. The pond is a multi-functional water storage tank that collects rainwater from the track area through a rainwater pipe network. It can store more than 70 percent of the rainwater of the whole construction area. When it rains, the pond can store a certain amount of rainwater to supplement the landscaping water demand. When heavy rain occurs, the pond can adjust and reduce the peak flow. Besides storing water, the pond also reuses rainwater that has been filtered and disinfected for greening, landscaping, and road watering.

In addition, all of the green vegetation in the depot is covered with gravel, coarse sand, fine sand, and other materials. It is equipped with multiple rainwater pipes, which can both absorb and store water. The sponge vehicle depot can achieve rain and sewage diversion transformation, saving an estimated 20,123.4 tons of water per year.