The Greenlawn Avenue Trash Filter



2019 by Alex Silbajoris, Friends of the Scioto River


The Greenlawn Avenue Dam is a lowhead dam spanning the Scioto River south of downtown Columbus, Ohio.

Inside the dam, a major sanitary sewer line crosses the Scioto on its way to the municipal wastewater treatment plant. For this reason, it is highly unlikely that the dam will ever be removed.

Above the dam, a pool forms part of the backdrop of the Grange Insurance Audubon Center and is designated as an Important Birding Area. Seen from the city park above the dam, the pool provides a foreground for a full view of the Columbus skyline.

There is no other dam on the Scioto anywhere south to the junction with the Ohio River. The next dams to the north are at the Dublin Road Water Treatment Plant (the municipal water intake) and the Dodridge Street Dam on the Olentangy River.




Below the dam lies a wooded floodplain which regularly floods, especially in winter.

When FOSR stages its annual Earth Day cleanup in April, a lovely carpet of invasive Lesser Celadine (Ficaria verna) blooms yellow, studded with various large trash items.

FOSR collaborates with the Central Ohio chapter of the Sierra Club, and the Ohio Game Fishing discussion board. Each organization recruits volunteers, and we typically have approximately 50 people on the site.




The floodwaters carry a significant amount of floating debris and trash. "Floating" means not only trash floating on the surface of the water; it includes a large amount of trash, mainly plastic bags and sheet plastic like tarps, with neutral bouyancy which lets it float unseen below the surface.

When high water passes through trees and undergrowth, the foliage snares this plastic, which is revealed when the waters recede. There's no way to know how much of this plastic passes by without being snared somehow, if not here then somewhere else downstream. Sometimes items like plastic grocery bags collect silt, and they sink, becoming embedded in the riverbank.They never decompose; the plastic eventually "photo-degrades" becoming brittle, and it breaks apart into smaller and smaller pieces.

br>


This is a small island just below the dam. The plastic shows how high the water level was. This is mostly light plastic like grocery bags.

The high water brings in all kinds of floating material, mostly sticks and logs. The sticks back up among the trees, creating jams which capture more floating debris. The water flows through, but the debris is captured. The majority of snagged waste material comprises small items like plastic bottles (sometimes capped glass bottles) along with styrofoam cups and pieces, snack food bags, etc.

We have found oddball items like wheels, tires, coolers, toys large and small, clothing, a bowling ball and a coconut. We have found a toilet, and police cruiser light bars (2). Some items are too bulky or filthy to handle without using hooks intended for straw bales.




When the water recedes back to normal river level, the litter is left behind logjams that strongly resemble beaver dams. It sometimes looks like someone came in with a truckload of litter, and dumped it.

The footing can be tricky and the scale of the task can be daunting. The volunteers swarm over it, filling bags and hauling large items. We provide gloves and hand sanitizer, along with beverages and snacks.

The plastic cannot be recycled because it isn't clean; the recycling center doesn't want a plastic bottle half full of grit, or a capped glass bottle with an Unidentified Yellow Liquid in it.(I tell the volunteers that if a bottle has liquid but no cap, pour it out at the longest possible arm's reach. If the bottle is capped,Do not open it.



Our volunteers really hustle, and they take pride in making a visible difference in the park. In past years we would make a heap of trash up by the entrance to the park, but now we leave everything under the Greenlawn Avenue bridge, out of most public view and where the Columbus Recreation and Parks crews have more room to gather it up without blocking traffic.