TECHNICAL UPDATE
TECHNICAL UPDATE | WATER MANAGEMENT
Dr Christian Spring STRI research operations manager
GOING UNDERGROUND PERMAVOID is an incredibly strong plastic tile, made from 90% recycled materials, that measures 0.71m x 0.35m and is composed of 95% air space. The system was originally developed for managing water as part of sustainable drainage schemes, such as under car parks. It can be ‘tanked’ by being wrapped in an impervious membrane, giving the ability to store tremendous amounts of water in a very flat profile. The water can then infiltrate into the soil over time or the outflow can be controlled to attenuate water. The system has evolved by the creation of wells in the tiles in which wicking cylinders can be inserted to create a passive irrigation system (the Blue2Green system) that can pull water out of the tanked tile, allowing it to be taken up by plants.
16 GROUNDS MANAGEMENT | JUNE 2020
In the laboratory STRI’s research encompassed a range of scientific trials: • Laboratory evaluation of the wicking system, its components and interaction with growing media • Field evaluation of the Blue2Green system in both arid and tropical climates • Field testing of Permavoid as a drainage layer and its ability to reduce rootzone depth • Permavoid’s use in temporary sports surface constructions • Integration of Permavoid in modular pitch solutions • Integration of pitch profile systems, such as Sub-Air, with a passively irrigated Permavoid raft. In all trials, Permavoid had benefits above conventional solutions alone.
Initial testing on evaluating the science and efficacy of the wicking components aimed to assess: • How did the wicking systems work and under what conditions did they work optimally? • How effective was the passive irrigation system at pulling water into the growing medium? • What spacing would be optimal in sports turf installation with typical sand-based growing media? The wicking components were tested by looking at the rate and extent to which dyed water was drawn up by the materials when they were sat in a reservoir of liquid (Fig 1). It became clear that when they were pre-charged with water, they tended to respond more rapidly than when dry (Fig 2). To evaluate how the wicking system
