A partnership with Citizens Energy Group and the City of Indianapolis

To help keep Indy’s Waterways Clean

Citizens Energy Group, Keep Indianapolis Beautiful, and the Indianapolis Department of Public Works have joined forces in a long-term partnership to plant 10,000 trees across the city as a way to beautify neighborhoods and reduce combined sewer overflows to area waterways. Keep Indianapolis Beautiful is excited to support Citizens Energy Group’s investments that will nearly eliminate combined sewer overflows (CSOs) to area rivers and streams by the year 2025.

10 Thousand Trees

  • Trees as a Solution to Combined Sewer Overflow

    What is a Combined Sewer Overflow (CSO)?

    Indianapolis’ original sewer system was designed to carry only stormwater away from streets, homes and businesses. Indoor plumbing meant sewage lines were hooked to these same sewers, combining stormwater and sewage in one pipe and sending it directly to our rivers and streams. These “combined sewers” were state of the art at the time.

    Today, CEG builds separate sewers for stormwater and sewage. However, combined sewers remain in many of the city’s older neighborhoods. During rain events with ¼-inch of rainfall or more, the combined system can cause raw sewage to overflow, called Combined Sewer Overflows (CSOs), into our streams and rivers causing a threat to public health. In the central part of Indianapolis, even a light rain storm can cause raw sewage to overflow and pollute Indianapolis waterways.

    Raw sewage overflows are a major cause of wet-weather pollution in portions of White River, Fall Creek, Eagle Creek, Pleasant Run, Bean Creek, Pogues Run, Lick Creek and State Ditch. Source: Citizens Energy Group

    Click on the image for a bird’s eye view of Indy’s sewer system from Citizens Energy Group. Source: CEG

    How do trees reduce the amount of stormwater entering sewers?

    One large tree can keep thousands of gallons of stormwater out of the sewers every year! Trees hold precipitation on leaves, branches, and trunk.  This reduces the amount of raw sewage that overflows into our streams.

    Do trees have other benefits beyond stormwater interception?

    Yes!  Trees positively affect our economy, safety, health, and environment. Here are a few that explain the benefits of trees:

    How are CSO basins identified for tree planting?

    KIB and CEG mapped Indianapolis to find areas with low existing tree canopy, high plantable space, and high impervious surface area that overlapped with CSO systems.

    Where will trees be planted within the selected CSO basins?

    KIB will identify tree planting locations within the city right-of-way along streets and in Indy Parks. KIB arborists take into account tree growth, survival factors and distance from existing infrastructure such as power lines, traffic control signs, street lights, and existing trees. For street trees, KIB identifies tree-lawns (the strip of grass between the street and sidewalk) large enough to accommodate large trees.

  • FAQs about Trees Planted In CSO Basins
    FAQs about Trees Planted In CSO Basins

    How large are the trees at the time of planting?

    New trees are typically about as tall as a person. Some species may reach 12 feet tall when planted.  These trees will be 1-2 inches thick near the base of the trunk.

    What species of trees will be planted?

    KIB will plant a diversity of tree species. 

    • Different tree species are susceptible to different pests and diseases. More species of trees means the overall urban forest will be less vulnerable to pests, diseases, and other threats.

    KIB will primarily plant tree species native to Indiana and contiguous states. 

    • Trees species that have been growing in Indiana and surrounding states for thousands of years are adapted to our local climate and soil conditions. Native tree species also support more species of butterflies and moths, which are an important part of our food web.

    KIB will plant large-growing species.

    • Larger trees can intercept significantly more stormwater than smaller trees.  Since the goal of the 10,000 trees initiative is to reduce peak stormwater flows, only large-growing species will be planted.

    When will trees be planted?

    Trees will be planted in the spring (March, April, early May) or in the fall (October, November, December).

    How will I know if I am getting a street tree in front of my house?

    Be on the look out for KIB staff leaving door hangers, flagging the tree lawn, putting a sticker on the curb or putting up yard signs on the ends of blocks to let you know that trees are coming. Attend your neighborhood association meeting to learn more!

    Who will plant the trees?

    KIB staff will lead volunteers in planting the trees.  Residents are welcome to volunteer to plant trees.  Sign up to volunteer at kibi.org/projects

    Who will maintain the trees?

    Keep Indianapolis Beautiful

    You & Your Neighbors

    • A large threat to young trees is trunk damage by mowers and string trimmers.  You can help the trees survive by being careful not to damage the trunks.
  • Common Myths About Trees

    Myth: “Trees break sewer lines.”

    Trees are not physically capable of breaking a sewer pipe.

    Tree roots can only get into a sewer pipe if it is already broken and leaking sewage into the soil. Many older homes have underground sewer lines made of clay tile pipes. These pipes are made of many short sections of ceramic pipe that are fitted together.  This pipe design, with its many short sections, is prone to leaking at the joints. Modern sewer lines are made of PVC and other materials that come in much longer lengths and can be connected to each other with much stronger bonds.

    Homeowners are responsible for keeping the sewer pipe on their property (sewer lateral) in working condition. Many plumbing companies offer video scoping of your sewer lateral free of charge. You can be proactive and have your sewer lateral scoped periodically, which allows you to catch any leaks before tree roots and other obstructions begin getting into your sewer line. If you sewer line needs to be replaced, techniques such as “pipe bursting” allow sewer lines to be replaced without digging a trench for the entire length of the pipe.

    Myth: “Trees destroy sidewalks.”

    Just like any other infrastructure, sidewalks have an average life expectancy. Some sources place the life expectancy of a concrete sidewalk in the Midwest at 30 years. The average life expectancy for people in the United States is about 78 years. If you lived near the same sidewalk your entire life, even with no trees nearby, you could expect that sidewalk to be replaced at least twice in your lifetime. Some sidewalks heave and crack without any trees nearby and end up needing to be replaced in less than 30 years.

    With that understanding, some sidewalk heaving is associated with tree roots; however, the way in which it happens is interesting. Like many materials, concrete expands when warmed and contracts when cooled. In the cooler months of the year, sidewalks contract, which can open up some space underneath the sidewalk. Sometimes tree roots grow into these new, open spaces under contracted sidewalks. In the warmer months, when the sidewalk expands again, newly grown roots may prevent the sidewalk from expanding into its former space. The result can be the sidewalk heaving or cracking.