To alleviate flooding downstream of the Holland area, CPG carried out hydrological analysis and hydraulic assessment; and proposed a detention tank is proposed along Tyersall Road under the proposed nursery and coach park for Tyersal Learning Forest, which is part of an 8 ha extension of the Botanic Gardens.

The footprint of the tank is 7000 m2 and it has a total storage capacity of 38,000 m3. This detention tank serves to temporarily store excess stormwater from the upstream catchment of Stamford Canal. Stormwater is intercepted by an adjustable overflow weir discharging into a sump alongside the existing canal on Holland Road.

The detention tank is equipped with a pumping system to evacuate stored stormwater and tank drainage, control gates and valves, pipework, plumbing and sanitary system, fire protection system and ventilation, mechanized silt and rubbish removal. It further includes a substation, SCADA system and telemetry link for remote operation. Inlet and outlet pipelines are also part of this scope.