From Gray to Green
You might have heard of “depaving”. The environmental restoration strategy, which involves removing existing asphalt or concrete and replacing it with trees, gardens, and green space, has recently been taking the internet by storm.
The Compact’s Depave initiative, which began in 2017, has removed 85,000 square feet of asphalt from Nashville so far, bringing beautiful green spaces and exciting environmental benefits to areas including Bellevue, South Nashville, and East Nashville.
Fast forward to now—Fall 2024—and the Depave initiative is breaking ground on an exciting milestone: its newest project at Calvary United Methodist Church in Green Hills is the largest depave project ever undertaken independently by Compact staff. The 6,000 square foot plot spans the length of the church parking lot, which is close to the length of a football field.
Yesterday’s Parking Lot: Tomorrow’s Green Space
The Calvary Depave project started with the identification of a problem: the church parking lot had an excess of spaces that attendees rarely used. At the edges, it was crumbling due to environmental degradation.
The church sits on six acres in Green Hills and 60% of the land is a paved parking lot to accommodate about 700 people. The lot is much larger than needed with only about ⅓ of the lot in frequent use. Parking lots are expensive to maintain as they need to be resealed, striped, and resurfaced every 10-15 years. Maintenance like this can cost in the range of $250,000. With Depave, this expense can be reduced and an asset in the form of green space can be added.
David Low, Facilities Manager at Calvary UMC, encouraged the depave project from the beginning. He is a native Nashvillian with a background in forestry and spent many years backpacking and camping with his sons’ Boy Scout troop. Under his care, Calvary UMC has planted 51 native trees through the Root Nashville campaign and now will add 16 more through the depave project.
The trees not only help beautify the grounds and provide shade but also filter pollutants, such as motor oil, that accumulate on the paved surface. Trees with deep roots prevent pollutants from reaching nearby waterways like Sugartree Creek and keep it clean for fish and wildlife.
Caring for the natural world holds an important place in David’s faith and he believes that people have a responsibility to steward the land in a way that will protect it for future generations. “I think we have to consider the kids, the grandkids, and the kids after that,” David says. “Paving this whole parking lot was the best decision at the time…but you know, it’s ok for that to change.”
When Compact Field Operations Division Manager Chris Hornsby took a concrete saw to the ground at Calvary to perform the initial site test on September 20, he commented on how monumental the day felt. “So much planning led up to this moment,” he said. “It’s surreal to actually be breaking ground to start greening this space.”
Chris, who is certified regionally and nationally in green infrastructure maintenance and inspection, elaborated on the benefits of depaving.
“Transforming this area from parking lot to green space will change the way water moves through it. It’ll have huge benefits for the Calvary UMC community, as well as pollinator insects, birds, and the environment on the whole.”
“Everyone knows that a parking lot is hot and miserable, especially in the summertime. But these hard surfaces like roads and parking lots also can’t absorb any water when rain falls on them,” explains Urban Waters Program Coordinator Natalie Stone. “Instead, that rainwater flows across the pavement, aka stormwater runoff. With too much stormwater runoff you start to see issues like erosion and ponding, which can damage yards, sidewalks, and homes, plus make roads difficult or impossible to navigate.”
Stormwater runoff also carries harmful pollutants—like chemicals, pet waste, and litter—straight into nearby streams and lakes (and eventually, in Nashville’s case, the Cumberland River, the source of our drinking water).
Environmental Benefits
Fortunately, depaving even a small part of a large paved area can reverse these problems. Depave projects of every size yield significant environmental benefits for the surrounding area and the people who live there.
Benefit 1: Beautification and Biodiversity
When a portion of a parking lot’s pavement is removed, native trees such as magnolia, black willow, and oak can be planted, creating a lush, shaded area for the community members to use and enjoy. The trees will provide shelter for songbirds and food for useful pollinators like bees and butterflies, whose habitat is threatened by urban development.
Benefit 2: Improved Water Quality for People and Animals
Trees are absorbent powerhouses that drink in an astonishing amount of water, rather than letting it run off like pavement does. When trees are planted in a depaved area, they capture and recycle rainwater that would otherwise become stormwater runoff, keeping pollutants out of nearby streams and rivers.
Fish and birds who rely on the creek for habitat and hydration will be healthier, and (in the case of Nashville, where drinking water comes from the Cumberland) the source of our drinking water will become cleaner.
Benefit 3: Reduced Stormwater Runoff Damage
By decreasing stormwater ponding and runoff in parking lots, streets, and yards, depaving can have an impact on the frequency of problems like potholes, flash flooding, and water damage to businesses and homes. It can lower maintenance costs for cities and property owners, putting time and resources back in their hands.
Benefit 4: Reduced Urban Heat Island Effect
Trees and other plants naturally cool the air through shade and the process of transpiration. Because of this, a depave project can help create a cooler neighborhood where it’s more enjoyable to spend time outside. This benefit is especially crucial for blossoming urban areas, which attract lots of pedestrians and public transit users.
One Parking Lot at a Time
The work required to depave Calvary UMC can be broken down into four steps:
- The Site Test: First, Compact staff removed a cross section of the parking lot to test the asphalt’s depth and density, which allowed them to estimate the cost and labor associated with the project.
- The Asphalt Removal: Next, a wet saw was used to slice the asphalt into small sections which could be lifted up and removed with an excavator. The broken up asphalt was then removed from the property with dump trucks.
The Calvary site after asphalt removal was complete. - The Scoop and Dump: To undo years’ worth of soil compaction and degradation in the newly depaved area, the team performed “scoop and dump” soil remediation on the site: First, they spread a layer of leaf compost. Then, using an excavator, they scooped up the compost and soil underneath and dropped it back down, mixing everything up. This process aerates soil while improving its quality, ensuring that it will be hospitable to young trees. On top, a layer of a special soil mixture was added to help filter pollutants from stormwater, retain moisture, and support healthy vegetation.
- Planting: River oats, a beautiful native grass that thrives in moist areas, will be sown throughout the Depave site. In December, serviceberries, crabapples, and sweet bay magnolias will be planted at the project site by Compact staff and volunteers. These trees will be provided by the Root Nashville campaign, which the Compact operates: they’ll count toward the campaign’s goal of planting 500,000 trees in Davidson County by 2050.
A Green Vision for Nashville’s Future
The new green space at Calvary UMC is projected to absorb half a million gallons of stormwater a year—that’s almost enough to fill an Olympic swimming pool! And that’s only a fraction of the impact the Depave initiative has had so far, factoring in the 85,000 square feet of other project sites all over Nashville.
In the future, the Compact team hopes to see Depave grow into a big movement, multiplying their efforts in urban forestry and native landscaping.
“Trees should be thought of as valuable urban infrastructure, just the same as a sidewalk or a bus shelter,” says Jason Sprouls, Urban Forestry Program Manager. Jason, an ISA board-certified arborist, heads up the Root Nashville campaign and will oversee the tree planting at Calvary UMC.
“I’ve worked on large tree planting campaigns in multiple cities, and generally the vision for the future is the same,” he explains. “We want to create an urban metropolis connected by green corridors and pockets. That’s the goal for Nashville as well—and Depave is amazing because it unlocks that potential even in areas that are highly developed and already paved over.”
The work at Calvary UMC was made possible by generous funding from Altria. The Compact is grateful for Altria’s commitment to protecting clean water and enhancing green space in our city.
Depaving a square foot of Nashville costs about $10. Every 100 square feet that is depaved can absorb approximately 2,500 gallons of rainwater annually. You can unlock the power to change Nashville’s landscape, keep our water clean, and nourish native plants and trees by making a donation to the Compact
Know a paved place you’d like to transform into a native plant garden or community reforestation site? Suggest a Depave site using the consultation form here.
