Green Infrastructures should be sustainable and cost-effective, but plant establishment and maintenance can be a roadblock. Only established plants create desired benefits of Green Stormwater Infrastructures, such as removing toxins, improving scenery, and providing cleaner air, which is why ensuring that plants used in Stormwater GI become established in their new environment is essential. Trees that die before reaching maturity incur planting and removal costs while creating little benefit in return.
Highly porous soil allows stormwater to drain and dry quickly. As a result, soil moisture fluctuates wildly. Few plants can survive in both swampy and desert soils. This is why in Fairfax, VA, two stormwater drain trees were installed with TreeDiaper® treemats to test if the product could help generate balance in this undesirable growing environment. A third tree was left without TreeDiaper® treemats as a control. The experiment started in December 2018.
On April 27th, 2019, both trees with TreeDiaper® treemats were observed to be alive while one of the control plants had died. When we visited this site, it was right around 30 hours after a 0.6" rain. The soil moisture under TreeDiaper® treemats was found to be ~7, while tree wells without TreeDiaper® treemats has a soil moisture of 3. For reference, the soil moisture in the regular plant bed was 10!
Another benefit of TreeDiaper® is to mitigate the effects of salt stress when snow melts and rock salt is introduced to the environment. TreeDiaper® treemats release water to dilute the salt concentration and protect the plants.
TreeDiaper® soaks up water during storms and retains it, allowing the plant to have a water source when the porous biofiltration area becomes dry, promoting healthier plants and more efficient biofiltration.
Greg Sager, Director, Hanover County Parks and Recreation, Virginia