When the NJ Tree Foundation plans for a tree planting event, concrete removal is a critical part of the project. Along portions of the Circuit Trail in Camden, areas with large sidewalks are prioritized as prime locations for street trees. Opening up the sidewalk to make space for a tree improves the health of the local watershed and the greater community.
Impervious surfaces like sidewalks, parking lots, and streets do not allow water to sink back into the ground naturally. Instead, when it rains, the excess rain picks up oil, debris, and other contaminants before making its way down the storm drain where it is dumped untreated into the nearest river, lake, or stream. This contributes to significant environmental pollution.
In addition, some parts of New Jersey including Camden and Gloucester City have outdated sewer systems called Combined Sewer Outfalls, or CSOs, which further add to water pollution. During normal, dry conditions, the combined sewer system works as planned. Sewage and stormwater are sent to the water treatment plant for processing. However, when it rains, the CSO becomes overwhelmed. Stormwater and raw sewage combine and overflow. The sewage water is then dumped untreated into the closest waterbody. CSOs contribute a significant amount of watershed pollution and flooding in urban areas. While Camden has seen a decrease in flooding in recent years, the CSO system is still a large contributor to water pollution.
What does this have to do with trees? Trees help to ease the burden on CSOs by soaking up excess stormwater. Trees act like water magnets. They absorb excess runoff and use their roots to filter out pollution. The NJ Tree Foundation creates two types of tree pits: enhanced and standard. The enhanced tree pits are designed for stormwater infiltration, and can intercept the runoff and reduce the amount of untreated water entering our waterways and flooding streets. For a standard tree pit we typically cut squares that are four feet by four feet, or sixteen square feet. We do not add any additional soil, and the trees are planted directly into the tree pit. When we construct enhanced tree pits, we look for areas that allow us to cut larger squares, bigger than our standard 4×4 cutout. These pits can range in size depending on the allotted space. Sand and gravel is mixed in with the existing soil to allow for greater water infiltration. Lastly, a PVC pipe is installed to increase airflow in the tree pit. The NJ Tree Foundation prioritizes removing concrete along the Circuit Trail in Camden & Gloucester Cities to make way for new tree pits.
Thanks to generous funding from the William Penn Foundation, the NJ Tree Foundation has removed hundreds of square feet of concrete that would otherwise contribute to stormwater runoff pollution. The NJ Tree Foundation looks forward to creating new tree pits and planting street trees both on and off the Circuit Trail in 2020.
