Preliminary study shows it's safe to remove Richmond's Weir Dam
Removing Richmond, Indiana's Weir Dam should not pose a significant risk of contaminating the Whitewater River. Researchers at Earlham College sampled sediments trapped behind the dam to determine risks associated with removing the dangerous low-head dam.
An independent, outside lab tested the samples and found only trace amounts of metals and hydrocarbons, and no legacy pesticides or PCBs, according to Shannon Hayes, an Indiana-licensed professional geologist and geology curator at Earlham. She notes contaminants typically adhere to clays, but the team of students and faculty found the area behind the dam contains about 70 cubic meters of sand and gravel rather than clay.
"It's really important to know what is behind a dam before removing it. This is particularly important in Richmond because one of the city's sources of drinking water is a well field located about one mile downstream of this dam," Hayes points out.
Researchers were somewhat surprised by the findings. The 10-foot dam was built circa 1913 to divert cooling water to the city's manufactured natural gas plant, Hayes says. Like many small industrial towns, much of the city's industry focused around the river.
"One result of this is that sediments accumulated behind dams record all this industrial history. When a dam is intact, the contaminates trapped behind it are buried and therefor they don't interact with the ecosystem very much or humans. However, if a dam fails or if it's removed, contaminated sediment can be released and it can cause significant problems."
Hayes points to the 1973 removal of the Fort Edward Dam that released PCB-contaminated sediments into the Hudson River. The area ended up as part of the Hudson River PCBs Superfund site that is still under monitoring.
Earlham College students participated in the research. Hayes says it was a great experience for them to have real-world applications to their classroom lessons.
"With the global pandemic it's been really difficult for field science students to get research experiences, and in this case, this was a ready-made opportunity to do real science and involve students on a project that matters," she says.
The Weir Dam has well exceeded its usefulness and lifespan. It's falling apart in places and poses a safety risk by creating dangerous recirculating currents that can lead to drowning. An 11-year-old child nearly drowned in May 2020 after becoming trapped in the waters while playing on the dam.
Richmond announced in October it had grant funding to remove the structure. The cost is estimated at around $165,000. More testing is expected before the project begins. The city is in the permitting and bidding process now and aims to begin removing the structure in late summer 2022.
The Richmond Sanitary District requested Earlham's help because it's in charge of permitting water discharges to the Whitewater River.
"They have to know exactly what's in the water and were concerned with what removing the Weir Dam might release," says Hayes.
Richmond's Parks and Recreation Department needs to know, too, because it wants to improve recreational opportunities in the Whitewater Gorge area.
"We want to really try to have more people have more access to our waters, our public waters," says Superintendent Denise Retz. "Here in the gorge, it's a really great asset. There are a lot of openings for people to access the water there - a lot of opportunities for tubing, kayaking, canoeing - and the low-head dam there poses a real safety concern to be able to have those opportunities."
The dam is a popular fishing spot and some people are concerned removing it will take away their favorite catch location. Officials dispute that, saying fishing will likely improve - along with overall river ecological health - once the dam is gone.
"They haven't known it any other way," Retz says. "They haven't seen the data of what happens when a dam is removed and how much fishery comes back to the area."
Low-head dams prevent fish and other species from swimming upstream, affecting their reproduction cycles. As previously mentioned, they're also incredibly dangerous because the churning water creates a reverse current that can trap people and lead to drowning.
According to the National Weather Service, the so-called "drowning machines" were responsible for 111 deaths nationwide from 2018 to 2020. Indiana documented 25 deaths near or at low head dams from 2010 to May 2020.