Curb Turn-Ins Direct Water to Trees

Constructing the tree planters. Curb turn-ins divert water to the trees.

Downtown Beautification Takes Off
Located northeast of Indianapolis, Anderson is home to 55,000 residents and one very creative assistant stormwater manager named Jeremy VanErman, who says the project began with the mayor wanting to do some downtown beautification.

“Because of our budget, we had to whittle this down to one street instead of two, and we did some preliminary drawings and conceptual planning, thinking first we would green it up with some trees and hardscape.”

But as the city found a lot of concrete deterioration, mix-and-match repair work, and instances of noncompliance with the Americans with Disabilities Act (ADA), VanErman says it also discovered that significant underground electrical components had failed.

Because the city has its own electric company, and anticipating future needs, VanErman’s team talked to the utility about putting in new conduit for the future that would accommodate traffic, safety, decorative lighting, and more.

“Trees, green space, and sidewalk repairs then became our scope after our needs analysis,” says VanErman. “At first we wanted to put in planter boxes, but I didn’t want to add burden to the parks people for watering and maintenance. Plus, we’re a combined sewer community, so when I devised the project in its final form it was really to reduce the workload of our staff.”

VanErman’s ingenious solution to manage the proposed new greenscape while reducinCredit: XERIPAVE Constructing the tree planters. Curb turn-ins divert water to the trees.g a watering maintenance effort was to capture the street stormwater and divert it to the treewells.

“I thought about turning the curb water into the trees, and one thing led to another. The design we came up with was to build curb turn-ins, and then I talked to Mark Walker about Xeripave. He helped us come up with an alternate design to accommodate the benefits of using pervious pavers.”

What they ended up doing was using the Xeripave around the trees, “like a rain garden on steroids,” he says.

“I didn’t have underground storm piping, so without building a rain garden, turning the water in and opening its passage to the trees through the curbs became my answer.

On the surface around the trees, the water passes directly through, and water from curb turn-ins passes through a Xeripave standing on end, allowing the street water to enter but blocking silt and trash.

“We had to support the pavers over a bridge gap, but we saw the flow rates and thought there shouldn’t be any reason it wouldn’t take a ton of water just by turning it on end,” he says. “This saturates the soil of the tree root ball and the sandy soil that backfeeds it. It’s a natural watering structure.”

The structure also accommodates growth of the tree trunks over time.

VanErman says the project has been about two years in the making, three years from start to finish. The original cost estimates not including the decorative streetlighting were around $1.2 million.

“We’re at 90% right now, and businesses love it, the look and the feel of the surfaces. Our arborist, Greg Spencer, helped pick out the most suitable plantings, and also trees that are salt tolerant for winter treatments as well as hardy and that can take a lot of water.”

Moreover, he says, it’s a model best management practice (BMP). “This project will do well as a BMP for the city; it’s a huge BMP for ­stormwater, groundwater infiltration, and ­offloading a lot of rainwater. We’re going to use it on another project since the pavers performed so well. Hopefully, Main Street is next, to be funded by the City Redevelopment Commission, Economic Development and Revitalization.”

“If there’s any work to be done, these pavers can be removed far less intrusively and then replaced easily. For the electrical maintenance, this means not having to tear things up and then try to cosmetically patch them back together,” he explains.
While VanErman concedes that there is a certain amount of maintenance—sediment that collects from the curb turn-in must be shoveled out—the benefits far outweigh those issues as the upside on low-cost maintenance is a “no brainer.”

“As far as I know, no one else has done this design element—no curb turn-ins and none combined with Xeripave. We have about five to six thousand cars a day go through this renovated block, and I hear good things all the time.” EC_bug_web

  • maderby.

    Nice design and elegant solution. Is there any type of barrier or diversion to prevent petroleum products or other contaminants from killing the trees?

  • Jeremy M. VanErman.

    No. There is no other barrier than the Xeripaver and the Soil itself. There is some (minimal) risk of losing trees due to over contamination/spills, etc. We will be monitoring and evaluating the impacts of the “dirty” storm water on the tree species. My apologies on the delay in the response – we received notice of the publication today.

  • Carrie Tauscher.

    what is the width inside the curbed tree planting “pit” and what species did you select. Can you provide the total soil volume accessible to the trees root system?


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