Shenyang Zhongzhi Xiyue Cuiyuan Rainwater Harvesting System Case: An “Invisible Sponge” in Tiexi Old Town Renewal

At Zhaogong South Street, Tiexi District, Shenyang, the Zhongzhi Xiyue Cuiyuan project is undergoing a transformation from an old industrial area into a livable community. As an ecological special section of this EPC general contracting project, Zhengzhou Yayuan Technology undertook the detailed design and construction of the park’s rainwater harvesting system. Faced with freeze-thaw climate in Northeast China and limited underground space, Yayuan Technology adopted PP modular water storage technology as the core, embedding a “breathable” underground network for this 29,000 m² mixed residential and commercial land parcel.

Project Background: Rigid Demand for Sponge Facilities in Cold Regions

Covering a total construction area of approximately 29,000 square meters, Zhongzhi Xiyue Cuiyuan is zoned for residential and commercial use. Amid Shenyang’s ongoing sponge city initiative, sponge city design was specified at the schematic stage. Low-impact development measures including infiltration, detention, storage, purification, reuse and discharge were required to control rainwater runoff pollution and realize on-site water resource utilization. Nevertheless, the site lies within the old Tiexi urban area with a dense, intricate network of underground pipelines. Located in a severe cold zone, the region suffers obvious frost heave in winter, setting strict requirements on structural strength and low-temperature resistance of water storage facilities.

Technical Solution: Cold-Resistant & High-Load PP Module System

Tailored to Shenyang’s climate and site load requirements, heavy-duty PP polypropylene rainwater harvesting modules (1200mm×600mm×300mm) were selected for the system. Manufactured via one-shot injection molding, the modules work reliably within a temperature range of -30℃ to 120℃, resisting brittle failure under Shenyang’s extreme winter cold. For load-bearing performance, reinforced module configurations were deployed where the top of the tank serves as fire lane or landscape green space. The design delivers a bearing capacity of 40–50 tons per square meter to guarantee safe above-ground operation.

In terms of layout, rainwater tanks are buried in a distributed pattern under green belts and hard pavements, without occupying valuable ground activity space. Roof and pavement runoff passes through pre-treatment by flow diverters for pollutant interception before entering the modular tank. After filtration and disinfection, harvested rainwater is reused for landscape irrigation and road washing, substantially easing the drainage burden on municipal sewer networks.

Construction Record: Refined Works Racing Against Frost Season

The short effective construction window and long winters in Shenyang create major schedule hurdles for underground concealed works. Upon mobilization, Yayuan’s construction team coordinated with the general contractor Shenyang Yunwei Municipal Construction Engineering Co., Ltd. to conduct detailed pipeline surveys on excavation zones. Excavation was carried out precisely by small machinery with manual assistance to avoid existing underground utilities.

During module assembly, units were interlocked in a staggered layout like building blocks, wrapped with impermeable geomembrane and protective layers. Given the relatively high groundwater table in parts of Tiexi District, crushed stone drainage blind ditches were installed at the base of foundation pits to prevent ponding and soaking of the trench during rainy-season construction.
From foundation casting to module capping and backfilling, all construction sequences were tightly coordinated. The full underground concealed works were completed before the arrival of frost season, reserving sufficient time for subsequent landscape works.

Project Value: An Ecological Footnote for Old Town Renewal

Once operational, the system grants Zhongzhi Xiyue Cuiyuan strong rainwater retention capacity. During heavy rains, the modular tank cuts peak runoff and relieves instantaneous drainage pressure on the municipal pipeline network along Zhaogong South Street. In dry spells, stored rainwater can partially replace tap water for park maintenance and cut property operation costs. For Tiexi District, this underground “invisible sponge” is not merely a mandatory compliant facility for new real estate development, but also a micro demonstration case showing the old industrial zone’s transition toward a low-carbon, green living environment. The cold-climate adaptation and compact-site construction expertise demonstrated by Zhengzhou Yayuan Technology on this project provide a replicable technical reference for future sponge city works on residential developments across Shenyang and broader Northeast China.