Sponge City Stormwater
Standards-Compliant Modular Systems for Urban Water Resilience
The six-character guideline — infiltration, retention, storage, purification, utilization, drainage — defines China's urban water paradigm. Yingyuan's EW Economy Series translates each character into a verifiable engineering component within a modular, installable, and maintainable system. From 20+ provincial standards to site-level performance verification, every element is traceable to code.
Sponge City Stormwater
Standards-Compliant Modular Systems for
Urban Water Resilience
The Six-Character Guideline
China's Urban Stormwater Framework
In 2013, China's central government articulated a new urban drainage philosophy in six characters: infiltration, retention, storage, purification), utilization, drainage. This framework reimagined the city not as a drainage machine that evacuates rainwater as quickly as possible (the grey infrastructure paradigm of the 20th century), but as a sponge that absorbs, cleans, stores, and reuses rainwater at its source. The policy was formalized in the Sponge City Construction Technical Guideline (2014), codified in CJJ 311-2020, and integrated into GB/T 50378-2019 (Green Building Evaluation Standard). By 2030, 80% of built-up urban area in sponge city pilot cities must meet the target total annual runoff control rate — typically 70-85% depending on the climatic zone.
For the civil engineer, drainage consultant, or landscape architect, this means every project — residential, commercial, municipal, industrial — must demonstrate quantified compliance with the annual runoff control target. Modular geocellular systems, specifically designed for infiltration and controlled-release attenuation, have become the default technology for achieving this at the source and community scales. Yingyuan's EW Economy Series is engineered to this regulatory reality: every specification parameter (090 pore size, infiltration rate through geotextile, storage volume per module, clip shear strength) maps to a clause in the relevant national or provincial standard.
From Six-Character Guideline to EW Module Engineering — A Traceable Translation
The Policy Framework
Six Characters, Three Scales
China's sponge city framework operates at three spatial scales: (a) source control — individual site or plot, managing rainfall at the point where it falls (infiltration, retention);
(b) community/conveyance — neighbourhood-scale drainage network, transferring excess runoff between source-control facilities (drainage, storage);
(c) city/regional — trunk drainage and flood storage, managing extreme events beyond the source-control capacity (drainage, storage).
Yingyuan's EW system operates primarily at scales (a) and (b), with application at scale (c) for distributed storage in municipal green corridors and urban parks.
EW Economy Series
The Engineered Match for Sponge City Applications
- Sponge City RequirementEW Response
- Shallow burial (1.2-2.5m) for source-control facilitiesEW module height 300mm; minimum cover 500mm; typical total burial depth 1.2-2.0m — well within the range of shallow trench excavation
- Pedestrian / light vehicle loading only (no HGV)SL-45 classification (45T axial ultimate); adequate for pedestrian, bicycle, car parking, and occasional light van loading; A15/B125 covers as appropriate
- 92% void ratio for maximum storage per excavation volume92% continuous void; 198.72 L/module; minimises excavation spoil quantity and off-site disposal cost — significant for urban sites with limited truck access
- Geotextile filtration meeting O90 specificationGTX-180 (180 g/m²) for infiltration; 090 0.07-0.12 mm; permeability≥ 5x10-3 m/s — exceeds CJJ 311-2020 geotextile requirements
- Manual assembly — no crane on constrained urban sitesModule weight 8.75 kg; 2-person crew; 50-70 modules per 8-hour shift; no crane, no mechanical plant for module placement
- Compliant with 20+ provincial sponge city standardsCompliance statement provided per project, mapping each system component to the relevant national + provincial + municipal standard clause
6 Character
Implementation Mapping
Infiltration
CJJ 311-2020 Section 5.2: EW modules in infiltration configuration — 180 g/m² GTX-180 geotextile full-wrap, no liner. Geotextile O90 0.07-0.12 mm matched to surrounding soil gradation. Infiltration rate through geotextile ≥ 5x10-3 m/s — exceeds the design infiltration rate for all soil types from sandy loam (10-5 m/s) to well-graded sand (10-4 m/s). The 92% void ratio provides temporary storage while infiltration proceeds.Retention
CJJ 311-2020 Section 5.3: EW modules in detention configuration with vortex flow control (110mm hydro-brake). The VFC limits discharge to the pre-development greenfield runoff rate (QBAR, typically 5-8 L/s/ha). During the critical storm, water is retained in the module void space and released at the controlled rate — attenuating the peak discharge by 70-90% relative to uncontrolled runoff. The VFC is a passive device: no power, no moving parts, no maintenance intervention required.Storage
CJJ 311-2020 Section 5.4: EW module at 92% void ratio: 1000x600x300mm module stores approximately 198.72 litres per module. Storage volume is calculated as: V = (catchment area x design rainfall depth x runoff coefficient x 1.1 safety factor) / 0.92 void ratio. The design rainfall depth is read from the local annual runoff control rate vs. rainfall depth curve published by the provincial housing authority.Purification
CJJ 311-2020 Section 6.2: Multi-barrier treatment train: (a) inlet silt trap (600L) captures gross pollutants and coarse sediment (>5mm); (b) geotextile wrap (O90 0.07-0.12 mm) retains suspended solids at the soil-module interface; (c) calmed inlet device prevents sediment re-suspension in the storage void; (d) floating suction filter (200 micron) provides final polishing for harvested water. TSS removal efficiency: 75-90% (system level, depending on inlet concentration and silt trap maintenance interval).Utilization
CJJ 311-2020 Section 7: EW modules in harvesting configuration: 2.0mm HDPE liner (GM-2.0) for impermeable storage, submersible pump on 316L stainless steel pedestal, floating suction filter drawing from 150mm below water surface, calmed inlet. Reclaimed water applications: landscape irrigation (garden, park, green roof), toilet flushing (after UV disinfection), road cleaning, construction water, agricultural irrigation (non-food crops). Typical residential harvesting storage volume: 10-30 m³ per building (supplying 30-60% of non-potable demand).Drainage
CJJ 311-2020 Section 8: Overflow/bypass configuration: when the module storage volume is full, excess inflow bypasses the tank via a high-level weir and discharges to the downstream drainage network (municipal storm sewer or open channel). The bypass elevation is set at the module crown to prevent surcharge of the upstream inlet pipe. For community-scale applications, multiple EW soakaway nodes are hydraulically connected in series — node 1 fills first, overflows to node 2, and so on, maximising infiltration before surface discharge occurs.Four Deployment Scenes
Sponge City in Practice
Landscape and Public Realm
Green Infrastructure Integration
The most visible sponge city application: modules beneath permeable paving, rain gardens, bioswales, and sunken green spaces in parks, plazas, streetscapes, and urban green corridors.
- ParameterValue
- Module seriesEW Economy, 300mm height
- Hydraulic functionInfiltration (geotextile wrap, no liner) — or hybrid infiltration + detention with liner and VFC where groundwater protection requires controlled discharge
- GeotextileGTX-180 (180 g/m²) for standard landscape; GTX-300 (300 g/m²) for tree-root-proximate installations
- Cover typeA15 pedestrian-rated PE lid or recessed tray cover accepting topsoil + turf/planting for invisible integration
- Burial depth0.8-1.8m (module crown to landscape surface)
Key Consideration: Aesthetic integration: the telescopic riser with recessed tray cover allows the inspection access to be concealed beneath turf or planting, meeting the landscape architect's requirement for invisible infrastructure. If the site also includes irrigation demand, the infiltration system can be upgraded to a partial harvesting configuration (liner + pump in a segregated compartment).
Project Reference: Municipal green corridor, Eastern China (Tier-2 city): 850 m³ distributed across 14 soakaway nodes, all under landscaped public realm. 3 years in service — infiltration rate maintained at 85% of design. Annual maintenance: CCTV inspection. No intervention required.
Residential Community
Plot-Level and Shared Stormwater Management
Housing developments (villa, mid-rise, high-rise) requiring: (a) per-plot soakaways for private gardens and driveways; (b) shared attenuation beneath access roads, parking courts, and communal landscaped areas; (c) rainwater harvesting for landscape irrigation and car washing.
- ParameterValue
- Module seriesEW Economy for shared areas (car parking, access road); PP Standard for private garden soakaways (cost-optimised)
- Hydraulic functionPer-plot: infiltration (soakaway). Shared: detention (with VFC) or harvesting (with liner, pump, floating filter)
- GeotextileGTX-180 for per-plot; GTX-300 for shared areas with tree proximity
- Cover typeA15 PE lid (per-plot, private garden); B125 ductile iron lid (shared, occasional vehicle)
- Burial depth1.0-1.5m (per-plot); 1.5-2.5m (shared under road)
Key ConsiderationPlot-level cost sensitivity: per-plot soakaway cost directly impacts developer margin. The EW module at 198.72 L/module achieves the required storage volume (typically 3-8 m³ per plot) with 9-24 modules per soakaway — installable in 3-4 hours by the general groundworks crew, no specialist subcontractor required. Shared harvesting systems can reduce the development's potable water demand for landscape irrigation by 55-85%, contributing to the green building rating (GB/T 50378, LEED, BREEAM).
Project ReferenceResidential development project (mixed villa + mid-rise), Southern China: 120 per-plot soakaways (EW) + 3 shared attenuation tanks (EW, 800 m³ total). Per-plot installation time: 3.5 hours average. Shared tank installation: 11 days (6-person crew). GB/T 50378 green building certification achieved.
Municipal Green Space
Distributed Storage and Water Reuse
Municipal parks, street greenbelts, riverfront buffers, and urban ecological restoration zones — implementing sponge city at the community and city scale. Typically part of a municipal government's sponge city annual implementation plan with quantified runoff control targets and post-construction performance verification.
- ParameterValue
- Module seriesEW Economy, 300mm height
- Hydraulic functionInfiltration (porous, no liner) beneath green space; detention + harvesting beneath hardstanding areas adjacent to green space
- GeotextileGTX-180 (infiltration zones); GTX-300 (detention zones, liner cushion)
- Liner (harvesting zones)GM-2.0 (2.0mm HDPE) for irrigation water storage
- Cover typeA15 recessed tray (green space); B125 ductile iron (maintenance vehicle access track)
- Burial depth1.5-2.5m
Key ConsiderationMunicipal procurement: public-sector projects operate on a different procurement cycle from private development. Yingyuan can supply via the project's main contractor (engineering procurement construction — EPC — model) or directly to the municipal government's framework agreement. Standard payment terms for public-sector projects: 30% advance, 60% on delivery, 10% on completion acceptance. Technical documentation package includes: compliance statement mapped to the municipal sponge city planning condition, material test certificates, installation method statement, and post-construction performance verification protocol. Municipal projects typically require the IoT monitoring kit for automated performance reporting to the city's sponge city data platform.
Project ReferenceMunicipal sponge city demonstration zone, Central China: 2,200 m³ distributed storage across 6 park and greenbelt nodes. 18-month performance monitoring data submitted to municipal housing authority as part of the sponge city completion acceptance. Data includes: continuous water level records (StormWatch IoT), quarterly infiltration rate tests, and water quality sampling for TSS, COD, and ammonia nitrogen.
Agricultural Reuse
Farmyard Runoff Capture and Irrigation Storage
Peri-urban agriculture and rural water management: capturing farmyard and greenhouse roof runoff; storing for spray irrigation, livestock watering, and aquaculture top-up. Addresses the seasonal mismatch between rainfall (concentrated in wet season/monsoon) and irrigation demand (peak in dry season).
- ParameterValue
- Module seriesEW Economy, 300mm height — or PP Standard for very shallow installations (greenhouse gutter storage)
- Hydraulic functionHarvesting — impermeable system with 2.0mm HDPE liner, submersible pump, floating suction filter, calmed inlet
- Pre-treatmentFirst-flush diversion (first 2-5mm) + two-stage silt trap (600L + 1200L in series, baffled)
- GeotextileGTX-300 cushion under liner and over module top
- Pump specificationSubmersible, 0.75-2.2 kW (site-specific), flow rate matched to irrigation system demand
- Burial depth1.5-3.0m
Key ConsiderationWater quality for agricultural reuse: the treatment train (first-flush diversion -> silt trap -> calmed inlet -> floating suction filter) is designed to meet the Class II agricultural irrigation water quality standard. For livestock drinking water, add UV disinfection downstream of the pump. Seasonal maintenance: silt trap vacuum cleaning before the wet season (prevent accumulated sediment being flushed into storage); floating filter mesh inspection at 6-monthly intervals. The IoT monitoring kit adds remote tank level and turbidity monitoring — useful for farms where the tank is distant from the farmhouse and daily visual checks are impractical. For agricultural grant scheme compliance (e.g., China's agricultural water conservation subsidy, or international schemes), Yingyuan provides a performance verification report template suitable for submission to the funding body.
Project ReferenceDairy farm, peri-urban area: 120 m³ harvesting tank (EW modules, 2.0mm HDPE liner, 2x 600L silt traps in series). Farmyard and dairy-shed roof runoff captured (~2,200 m² catchment). Reclaimed water supplies 65% of washdown and pasture irrigation demand. Payback period from reduced mains water charges: 3.8 years.
EW Economy Series
Sponge City Operational Advantages
Source-Control Architecture
Treat Rain Where It Falls
The fundamental principle of sponge city design is source control: manage rainfall at or near the point where it contacts the ground, rather than conveying it to a distant, centralized facility. EW modules enable this distributed architecture: multiple small soakaways (5-20 m³ each) placed under individual landscape zones, connected hydraulically but structurally independent. This distributed approach provides resilience — failure of one soakaway (e.g., siltation from a construction-phase sediment release) does not compromise the entire system. Maintenance can be performed on one node without taking the others offline. And the modular form factor allows soakaway placement in the irregularly shaped residual spaces between utilities, foundations, and tree root zones that characterize constrained urban sites.
Source-Control Architecture
Treat Rain Where It Falls
Treat Rain Where It Falls
15-Year Geotextile Service Life
Aligned with Module Life
Aligned with Module Life
Regulatory Documentation Pre-Packaged
From Planning to Acceptance
From Planning to Acceptance
Scalable from Plot to City Scale
One Technology Platform
One Technology Platform
Winter Construction
Operational Below Freezing
Operational Below Freezing
EW Sponge City Fact Map
Key Performance Benchmarks
- ItemValue
- EW module ultimate axial strength450 kN/m² (SL-45 classified, CJ/T 542-2020)
- EW module dimensions (LxWxH)1200 x 600 x 300 mm
- Storage per EW module198.72 litres (at 92% void ratio)
- Module weight (unfilled)8.75 kg
- Geotextile O90 pore size (infiltration)0.07-0.12 mm (GTX-180)
- Geotextile permeability (vertical)≥ 5x10-3 m/s
- Geotextile projected service life≥ 15 years (virgin PP continuous filament)
- Standard burial range (source control)0.5m cover to 2.5m depth
- Deep burial maximum (EW)4.0m (non-traffic only)
- Installation rate (2-person crew)50-70 EW modules per 8-hour shift
- TSS removal efficiency (system level)75-90%
- Chinese cities in rainfall database200+ cities, pre-loaded design rainfall statistics
- Provincial standards mapped20+ provincial sponge city guidelines
- National pilot cities (sponge city program)30 cities (batches 1 and 2, 2015-2016)
- Installed reference — municipal sponge city demo zone2,200 m³ distributed across 6 nodes (Central China)
- CCTV inspection interval (with IoT monitoring)2-3 yearly (vs. annual without IoT)
Sponge City Modular vs. Traditional Approach
Traditional Benchmark
Traditional grey infrastructure: deep-buried concrete detention tanks, large-diameter storm sewers, end-of-pipe treatment. High excavation cost, extended construction duration, no infiltration function, no water reuse capability. Runoff control: conveyance-dominant — discharges to receiving water with minimal attenuation or treatment. Land take: large footprint for detention basins. Maintenance: confined-space entry for structural inspection.
Yingyuan Approach
Yingyuan EW sponge city system: source-control modular facilities, shallow burial (1.2-2.5m), infiltration + controlled detention + harvesting in a single integrated system. Runoff control: infiltration-dominant at source, attenuation at community scale, discharge only when capacity exceeded. Land take: zero surface footprint — all infrastructure underground beneath landscape. Maintenance: non-confined-space CCTV inspection via riser. Standards compliance documented for planning approval and completion acceptance.
How Yingyuan Supports Your Sponge City Project From Planning to Acceptance
NO.1
Project Parameter Collection
You provide: project location (city/district), site area (m²), catchment surface types and areas, annual runoff control target (if known — otherwise we derive from local standard), groundwater depth, soil infiltration rate (from percolation test or geotechnical report), and project type (residential/commercial/municipal/agricultural).
NO.2
Compliance Analysis and System Design (3-5 Working Days)
Yingyuan's application engineer reviews your parameters and produces: storage volume calculation with local rainfall statistics, module count and layout recommendation, geotextile/liner grade selection, compliance statement mapped to applicable national/provincial/municipal standards, and a preliminary cost estimate.
NO.3
Quotation and Documentation Package
Formal quotation with SKU codes, quantities, unit pricing, delivery schedule, and the full compliance documentation package for planning submission. Module placement drawing and geotextile/liner cutting plan included as PDF attachments.
NO.4
Installation Support and Completion Acceptance
On-site supervision (first day, included with orders over 200 modules), remote video support throughout installation, and post-construction performance verification protocol for the completion acceptance inspection.
Ready to design your sponge city system
for compliance and performance?
Compliance Analysis Within 5 Days
Standards Compliance Matrix
National, Provincial, and Municipal Regulatory Mapping
National Standards — The Regulatory Core
- StandardFull NameScopeYingyuan Compliance
- CJJ 311-2020Technical Specification for Sponge City ConstructionComprehensive sponge city design, construction, and acceptance — all facility types, all scalesEW module system maps to Sections 5 (source control facilities), 6 (water quality), 7 (water utilization), and 8 (drainage safety). Full compliance statement available.
- GB/T 50378-2019Green Building Evaluation StandardGreen building rating — stormwater management contributes to Land Saving and Water Saving scoring categoriesEW harvesting system with IoT monitoring provides evidence for Land Saving (stormwater management) and Water Saving (non-traditional water use) credits. Compliance letter issued with system order.
- GB 50014-2021Standard for Design of Outdoor Wastewater EngineeringStormwater drainage design — rainfall intensity formula, pipe sizing, detention designEW detention system with VFC discharge control is designed per GB 50014 rainfall intensity methodology. Storage volume calculation references the local statistical rainfall data.
- CJ/T 542-2020Modular Rainwater Storage UnitsProduct standard for modular storage units — material, mechanical properties, test methodsEW module tested and classified SL-45 per CJ/T 542-2020. Test report available. Module material: recyclable PP, UV-stabilized.
- GB/T 17639-2008Geosynthetics — Nonwoven GeotextilesMaterial standard for non-woven geotextile — mass, tensile, puncture, permeability, 090GTX-180 and GTX-300 manufactured to GB/T 17639. Third-party test certificate provided with each batch.
Provincial and Municipal Standards — Regional Adaptation (Selected Examples)
- RegionStandardKey RequirementYingyuan Response
- BeijingDB11/T 1743-2020Annual runoff control rate target: 85% (core urban area); design rainfall 33.6mm (85th percentile). Infiltration facility area not less than 50% of total sponge facility area.EW infiltration configuration achieves the 50% area requirement. Storage volume calculated from 33.6mm x catchment area x runoff coefficient with 1.1 safety factor.
- ShanghaiDG/TJ 08-2230-2017Annual runoff control rate: 80% (central urban), 85% (new urban). Design rainfall 26.7mm (80th), 33.4mm (85th). High groundwater table — buoyancy assessment mandatory for all underground storage.Anti-flotation anchoring kit specified where groundwater within 1m of module base. Storage volume calculated from Shanghai-specific rainfall statistics. Shallow configuration (1.2-1.8m) preferred to stay above or near groundwater table.
- GuangdongDBJ/T 15-173-2019Annual runoff control rate: 70% (Guangzhou, Shenzhen — high rainfall intensity zone). Design rainfall depth varies by city — 24.5mm for 70% control in Guangzhou. High-intensity short-duration storms dominate — detention design must consider 5-minute peak intensity.VFC sizing accounts for high-intensity short-duration storms — orifice diameter selected to pass the 5-minute peak at acceptable head without backing up inlet pipe. Storage volume sized for the 70% control rate design rainfall (city-specific).
- SichuanDBJ51/T 081-2017Annual runoff control rate: 80% (Chengdu basin). Design rainfall 28.2mm. Seismic zone consideration (Chengdu is Seismic Intensity VII) — modular connections must maintain integrity under seismic ground motion.EW connector clips designed with 0.20mm interference fit — maintains interlock under seismic ground motion. System-level flexibility (individual module movement accommodation) absorbs differential displacement better than rigid concrete tanks.
- ZhejiangDB33/T 1167-2019Annual runoff control rate: 75-85% (city-specific). TSS removal ≥ 60% for all sponge facilities. Quarterly water quality monitoring for 2 years post-construction for public projects.EW treatment train (silt trap + geotextile filtration + calmed inlet) achieves 75-90% TSS removal. IoT water quality monitoring option (turbidity sensor) for automated quarterly reporting.
FAQ
Frequently Asked Questions for
Wholesale & Projects
Are the materials safe for environmentally sensitive projects?What prevents the crates from collapsing under deep burial?How do these crates comply with AASHTO H-20 standards?