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Issues of the Environment: Progress and next steps in Ypsilanti for removing defunct dam from the Huron River

Rebecca Esselman
Huron River Watershed Council
/
hrwc.org
Rebecca Esselman

Overview

  • The Peninsular Paper Dam, a decommissioned hydroelectric gravity dam and former paper mill and power station crossing the Huron River in Ypsilanti, is one step closer to being removed and restoring the natural flow of the river. Today, the dam is defunct. A shell of the original paper mill holds up the original large mill sign which is considered a prominent and historic landmark in the city of Ypsilanti. The city hopes to remove the dam, heal the river, and preserve this landmark. 
  • Recently, the Pen Dam has crossed another hurdle toward removal. In April 2022, the City of Ypsilanti hosted a Town Hall update event. Limnotech, a firm hired to take samples of the sediment material trapped in the dam impoundment and test for environmental contaminants, presented findings from their sediment report and HRWC shared an overview of the restoration process. Key takeaways: 
  1. The impoundment contains an estimated 270,000 cubic yards of sediment. 
  2. In an estimate of 135,000 cubic yards of this sediment that would be required to be removed from the future river channel to support the restoration. The remainder of the impounded sediment may require stabilization and restoration as a part of the floodplain adjacent to the river.
  3. Much of the sediment does not contain levels of environmental contaminants that require careful disposal in a landfill to prevent dispersing the hazardous material into the river. The sediment sampling results show that there are only 2 out of the 33 sampled locations in the Peninsular Paper Dam impoundment where the pollutants exceed the sediment quality goals for public health. While there were more locations that had exceedances of the sediment quality guidelines for ecological protection, overall, the pollutant levels in the sediment are low enough that majority of the sediment can be managed safely, and potentially re- used, either on site in the restored floodplain or upland areas, or offsite. (Source: *directly quoted* https://www.hrwc.org/wp-content/uploads/Pen_Dam_LimnoTech_2022_Report_Final_Combined.pdf)
  • HRWC is supporting the City in planning for the dam removal, the restoration of the river, and the revitalization of Pen Park. More specifically, HRWC is providing technical expertise, advice, assistance with fundraising and funding, and facilitation. All decisions are made by the City. Rebecca Esselman, Executive Director of the Huron River Watershed Council, did not give an updated timeline, but because few of the sediment samples contained concerning levels of environmental contaminants, including arsenic, the project could be less complicated. 

Removing the Pen Dam

Although inspections in 2018 found the Pen Dam in fair condition, it is classified as having a "high" hazard potential classification, meaning a failure would result in significant damage. (Source: https://cityofypsilanti.com/DocumentCenter/View/1789/2018-11-21-Peninsular-Dam-Removal-Study-Report)

In 2019, Ypsilanti city council voted to remove the dam, and $500,000 was allocated toward the deconstruction of the dam. Later estimates put the cost of removal at $2.7–4.3 million, which does not include engineering costs, cost of permitting, the cost of mitigation of the sediment, which contains toxic materials, the cost of railroad bridge scouring mitigation, the cost of restoration of the uncovered land, and cost of bank stabilization.

The Michigan Department of Natural Resources (MDNR) considers removing Pen Dam a priority for improving river health, fish habitat, and recreation. MDNR first recommended removal of Pen Dam in 1995.

Limnotech Findings

The scope of work for the project was to perform substantial data collection and preliminary analyses to support future design and construction activities to remove the Peninsular Paper Dam, located on the Huron River in Ypsilanti, MI. The data collected during this phase of the project includes a geomorphic and bathymetric survey of the impoundment and river channel downstream of the existing dam, depth of refusal survey in the impoundment, sediment cores collection and analysis for legacy contamination for metals and PAHs.

This data will be critical to inform in the future design process in particular to prepare a sediment management plan and restoration plan for the floodplains that will be exposed. As a part of this project, the bathymetric data and geomorphic data were used to develop a hydraulic model that can be used throughout the design process to inform the channel restoration design. The model was applied for a preliminary channel design from the Feasibility Study to evaluate the potential for scour at the Superior Road bridge and Norfolk-Southern Railroad bridge over the existing impoundment.

Some of the key findings from this study are:

  • The depth of refusal survey allowed for a more accurate projection of the volume of sediment that has accumulated in the impoundment since the dam construction. The feasibility study included a wide range in their estimate of the sediment volume of up to 1 million cubic yards. The bathymetry and depth of refusal survey performed by Inter-fluve for this project resulted in an estimated 270,000 cubic yards of sediment currently trapped in the impoundment.
  • Based on the results of the depth of refusal survey, it is estimated that there are approximately 270,000 cubic yards of sediment trapped in the impoundment. The geomorphic assessment and recommendation of typical cross section dimensions results in an estimate of 135,000 cubic yards of this sediment that would be required to be removed from the future river channel to support the restoration. The final project costs will depend heavily on the methods of removal, re-use (if possible), and/or disposal of this sediment, which will need to be determined during the final project design. The remainder of the impounded sediment may require stabilization and restoration as a part of the floodplain adjacent to the river.
  • The geomorphologic assessment of the site and reaches of the Huron River downstream indicate that the portion of the existing impoundment between the Railroad Bridge and Peninsular Paper Dam will likely be a high-gradient channel, with steep valley walls, similar to the conditions immediately downstream of LeForge Road. Upstream of the railroad bridge, the river channel would have a lower gradient, and a wider cross section, with historical river meanders.
  • The preliminary hydraulic model shows that for the area within the impoundment, the 100-year floodplain is decreased, potentially removing an existing structure from being impacted floodwaters under this event.
  • The scour analysis performed at the Superior Road and Railroad Bridges demonstrates that these structures will require scour protection to prevent the erosion from undercutting the structural supports.
  • The sediment sampling results show that there are only 2 out of the 33 sampled locations in the Peninsular Paper Dam impoundment where the pollutants exceed the sediment quality goals for public health. One of those locations is immediately adjacent to the future river channel, and that sediment will need to be removed, leaving only one future upland location with an exceedance of the arsenic background levels. Sediment with pollutant levels that exceed the guidelines for aquatic ecosystem protection will need to be remediated as a part of the restoration. If this sediment does not exceed the Part 201 guidelines for the adjacent land uses, it may be re-used as a fill, with appropriate handling and protection. It may require disposal in a landfill if it exceeds the Part 201 guidelines, which will require the contractor to track the source through a chain of custody to the disposal site.
  • While there were more locations that had exceedances of the sediment quality guidelines for ecological protection, overall, the pollutant levels in the sediment are low enough that majority of the sediment can be managed safely, and potentially re- used, either on site in the restored floodplain or upland areas, or offsite. Ideally, the site would be balanced between the amount of cut or sediment removal, and areas where the sediment could be placed on-site. At least half of the 20 locations where the ecological criteria were exceeded are estimated to be in the future floodplain, where they would not be detrimental to the to the benthic organisms that live in the river channel.
  • The design of the dam removal, sediment management plan, and channel and floodplain restoration design are interdependent processes that will evolve iteratively through the design process. This will require ongoing coordination with the grant funding and regulatory agencies, as well as with the project stakeholders.

What about the park and the Pen Paper Mill Building?

With the dam removed, the size of Peninsular Park would increase to include the land on the north side of the river that is currently submerged behind the dam. The full potential of Pen Park can be realized because the entire stretch of waterfront would no longer be divided by the dam. The former powerhouse, with its distinctive architecture and landmark neon sign, could be preserved and restored to provide a signature waterfront location for community residents to come together, celebrate Ypsilanti’s local heritage, and enjoy the river. The City of Ypsilanti owns the building and the park so the restoration of the powerhouse and options regarding its future use are entirely up to the city. (Source: *directly quoted* https://www.hrwc.org/what-we-do/programs/dams-and-impoundments-program/ypsilanti-peninsular-paper-dam/)

Dam Removal Process 

Many people think that when a dam is removed it is simply blown up. The truth is that, when it comes to dam removal and river restoration, explosives are used only on rare occasions and largely to help dismantle the structure and make excavation easier. The exact removal method for a dam depends on the size of the structure, the material it is made of, and several other factors. In most cases, blowing up a dam is not feasible because of the potential for environmental damage or the dam’s location in a developed or urban area.

Regardless of the methodology, heavy construction equipment are almost always present. Two questions to consider in how a dam is removed are:

Should the dam be removed “in the dry”? Removing a dam “in the dry” essentially means that the river is, in some way, diverted or pumped around the active construction site and that, at no time, is construction equipment in the water. The alternative to this is working “in the wet”.

Should the dam be removed all at once or in stages? - Once work begins to remove many small dams, deconstruction continues until the dam is gone. However, there are also times when a dam is removed in stages, being slowly lowered over a number of days, months, or years. This can allow the project team to manage things like sediment released from the former impoundment. The dams removed from Washington’s Elwha and White Salmon rivers, for example, were initially breached to allow the impoundments to dewater and the submerged areas to dry prior to deconstruction.

There are pros and cons to each of these methods. The method selected should be the one that is right for the river and dam being addressed. To avoid undue harm during dam removal, construction is undertaken in careful steps to not only avoid unacceptable degradation but also to keep dam removal contractors, their equipment, and people downstream out of harm’s way.

Is It Cost Effective To Remove A Dam? Dam removal can be expensive in the short term, but in most cases where dams have been removed or are being considered for removal, money is actually saved over the long term. Removal eliminates the expenses associated with insurance coverage, maintenance and safety repairs, as well as direct and indirect expenses associated with fish and wildlife protection (e.g., fish ladders and mitigation for fish mortality). In addition, removal often generates income from newly available recreation opportunities – including fishing, kayaking, and rafting – which may actually result in a net economic benefit. In some areas, dam removal may allow resumption of commercial fishing activities.

Will The Removal Of A Dam Matter If Other Dams In The System Are Not Removed? Some rivers are so heavily developed and dammed that removal of one dam on that river will only return flows to a small portion of the river. Generally, dams that have been targeted for removal are strategically located – removal will open up a section of the river critical to fish and wildlife and/or recreation. In some cases, this additional section of river is enough to sustain crucial populations of endangered or threatened species of fish, mollusks, and other wildlife.

How Does Dam Removal Affect Fish? - Dam removal benefits fish in many ways, including: (1) removing obstructions to upstream and downstream migration; (2) restoring natural riverine habitat; (3) restoring natural seasonal flow variations; (4) eliminating siltation of spawning and feeding habitat above the dam; (5) allowing debris, small rocks and nutrients to pass below the dam, creating healthy habitat; (6) eliminating unnatural temperature variations below the dam; and (7) removing turbines that kill fish.

What Are The Potential Downsides To Dam Removal? - Dam removal does result in fundamental changes to the local environment. The reservoir will be eliminated, and with it the flat-water habitat that had been created. Wetlands surrounding the reservoir may also be drained, although new wetlands are often created both in the newly restored river reach above the former dam site and in the river below. Sediment that collects behind a dam, sometimes over hundreds of years, may contain toxics such as PCBs, dioxide, and heavy metals. Removal of these toxic materials is often extremely expensive, and the threat of re-suspending these toxic-laden sediments in the process of dam removal has the potential to damage downstream water quality and threaten the health of fish and wildlife and water users. These impacts, however, can be prevented through proper removal techniques. Short term impacts of the dam removal itself can include increased water turbidity and sediment buildup downstream from releasing large amounts of sediment from the reservoir, and water quality impacts from sudden releases of water and changes in temperature. It has been demonstrated that these short-term impacts and greatly outweighed by the quick recovery of the system and the long-term benefits that result.

How Quickly Do Rivers Recover After Dam Removal? - Rivers are very dynamic and resilient systems. Experience has shown that natural river systems can be restored relatively rapidly after dam removal. For example, American eel were seen crawling through the breached section of the Harvell Dam in Virginia amidst its removal, spawning fish returned to the Souadabscook River in Maine only months after a dam was removed, and the flushing of the sediment from the Milwaukee River in Wisconsin following the Woolen Mills Dam removal took only six months.

(Source: *directly quoted* https://www.americanrivers.org/threats-solutions/restoring-damaged-rivers/how-dams-are-removed/)

Transcription

David Fair: This is 89 one WEMU, and welcome to a dam issue of Issues of the Environment. I'm David Fair, and, of course, I'm referring to the old Peninsular Paper Dam in the Huron River in Ypsilanti. The nonfunctional dam has been designated for removal, and the river through that area is going to be restored to natural flow. While another step has been taken towards that goal, more work lay ahead. Our guest this morning represents an organization supporting the removal of the dam and has been working with the city and others toward that end. Rebecca Esselman is executive director of the Huron River Watershed Council. And, Rebecca, welcome back to WEMU.

Rebecca Esselman: Hello, David. Thank you for having me.

David Fair: Now, last month, the city of Ypsilanti hosted a town hall to update the community on the process of removing the dam and provide an overview of the river restoration process. The first part of the update came from Limnotech. Now, that's the firm that was hired to take samples of sediment materials trapped in the dam impoundment and to test for environmental contaminants. Was it a good news or bad news report from Limnotech?

Rebecca Esselman: The news was about as good as it can get for a dam removal, and that was really heartening. In 2018, a feasibility study was conducted as we were working with the city that's planning to determine the feasibility of removing Peninsular Dam. And we got some sense of what we might see in the improvement from a sediment perspective. What Limnotech shared with us from the sediment analysis is that we really got a best-case scenario. The volume of sediments that are in the impalement are on the low end of the range from what we've estimated from the feasibility study. And the contaminant levels are very manageable.

David Fair: As you mentioned, the majority of the sediment was found to be below contaminant levels that would pose a threat to public safety. Can that sediment be reused in the river restoration project?

Rebecca Esselman: There's a bunch of different opportunities or options for the fate of that sediment. There will be some that's very actively managed, which means removed from the site. Some that will be passively managed, which means allowed to pass downstream. And of the sediments that are actively removed, there's a bunch of different fates there as well. So, sediments that do not have contaminant levels that exceed certain human health criteria can be actually used in the restoration, like for floodplain restoration. Other sediments may be removed offsite and could be used for fill nearby. Only in the most contaminated situation are the sediments actually moved to a landfill. And we'll know a little bit more about if we have that type of sediment and how much when we get a little further down the road.

David Fair: Beyond the sediment and Limnotech's address to the town hall, the Huron River Watershed Council made a presentation as well. What was your message on the work that's being done on the project?

Rebecca Esselman: We wanted to communicate to the city of Ypsilanti and residents interested in this project how really unique and exciting this project can be, both for the city and for the environment. A couple of weeks ago, we had the opportunity to share the results of the sediment analysis with the group and also our restoration plan, which is, I think, where some of the most exciting, you know, take homes are for me. You know, we have a stretch of river through Ypsilanti that is really unique in the Huron River system and actually really unique in southeast Michigan. It's a little higher gradient than most of our rivers, which means they kind of drops in elevation a little bit faster. And what that means from a river health perspective is that when restored, that stretch of river will have really diverse habitat, which will support fish species and fish populations, our mussel species, and all the aquatic life that calls the Huron home. So, the restoration plan is really bringing to light all of the potential benefits of this restoration as we move through this process.

David Fair: 89 one WEMU's Issues of the Environment continues, and we're talking about removal of the Peninsular Paper Dam from the Huron River with Rebecca Esselman. She serves as executive director of the Huron River Watershed Council. Rebecca, so many aspects of our lives were delayed or put on hold through the worst of the pandemic. Did it also slow progress on the process of getting to the point of dam removal?

Rebecca Esselman: I think, in 2020, there was a little slowing. You know, one tangible example of that is that, if you recall, the state got pretty conservative about spending for a period of time because we didn't really know what impacts the pandemic would have on the state's economy. So, there was a little bit of a delay in our first grant award that came from the state of Michigan. So, there were some delays, although not particularly significant delays. So, we're moving forward at a really reasonable pace was the other compromise we had to make. We did community engagement in meetings last fall, and those meetings had to be done virtually. And we definitely lose something from virtual engagement. And just, you know, you can't replicate that in-person environment. We were able to resume an in-person town hall in April, which was pretty exciting. I'd say, all in all, we've been able to keep the project moving through the pandemic.

David Fair: Well, you mentioned the uncertainty about finances and money. Well, in 2019, Ypsilanti allocated a half million dollars toward deconstruction of the dam. And the price of everything is soaring right now. Inflation is on high. Is a revised budget somewhere in the future?

Rebecca Esselman: Our feasibility study showed about 2.7 for removal. It was that feasibility study was a few years ago now. And we're seeing costs go up across the board, especially with infrastructure and construction. So, I do anticipate that we will see some additional costs. But the City of Ypsilanti's commitment of half a million is capped at half a million, and they are not responsible for the full cost of removal of the dam. Instead, the balance will come from our fundraising effort. There are a lot of state and federal agencies that are highly supportive of dam removal and river restoration, and we are working with those agencies to secure funding for the balance of the project, no matter what that balance ends up being.

David Fair: Once again, we're talking with Huron River Watershed Council executive director Rebecca Esselman on WEMU's Issues of the Environment. Once the dam is removed and natural flow restored, one of the more exciting aspects will come into play. And that's the expanded Peninsular Park on the north side of the river. Have you been able to assess what kind of land space that's going to create?

Rebecca Esselman: We have. It looks like there'll be additional two acres of park, so it's not huge, but it's not insignificant. And there will also be an opportunity to do some enhancements to that park as the city and its residents prioritize for things like river access and fishing.

David Fair: So, you've already pointed out some of the many environmental benefits that come along with removing the dam for the Huron River and its ecology. Are there any potential adverse impacts that could result?

Rebecca Esselman: I'd be hard pressed to name one, David. You know, this is a 10,000-year-old river that's been dammed for a little over 100. What we are really doing is restoring that river to what it's always been, and the ecosystem will recover over time. And it's just moving it back in the direction of being a free-flowing system, which it always has been and was evolved to be. So, I'd really be hard-pressed to name a negative outcome of this removal for the ecosystem itself.

David Fair: So, as we sit here today and with that to look forward to, do we have a sense of timeline? When might we see that naturally flowing river once again?

Rebecca Esselman: Yeah, at this point, I would look out to about 2024. So, we are, you know, very actively in what I would call phase two of the project. Phase one was all that background research that led to the city of Ypsilanti being able to make an informed decision about removal. Phase two here is all of that design and planning and research that has to go into making sure that when it does come time to remove the dam, that we know exactly how we're going to do it. And we are probably about halfway through phase two. We just receive some additional funding from the state of Michigan to build upon what Limnotech presented a few weeks ago about the sediment analysis, about the shape of the channel, once the dam is removed, about what needs to happen to the bridges that cross the river within the impoundment. And we'll build on that in this in this next year-and-a-half. At the same time, we're going to be doing things with the ecosystem. One of the critical elements coming up is a mussel survey. Mussels, of course, can't move out of harm's way. And we do have some nice mussel population in the river and a lot of potential for, you know, future growth for our mussels. And we really want to do that right. And there's actually a lot of regulation and process by our friends at the state agency, like the Department of Natural Resources, to make sure we do it right. So, in the next year-and-a-half, we will be, you know, looking for where those mussels are and potentially even relocating them before we remove the dams, so that they are out of harm's way during active removal. So, that still has to happen before we can actually remove the infrastructure. So, let's say 2024. Dam removal is a lengthy process that we want to do right. And we will take all the necessary steps we need to make sure that when it does come time for removal, we're ready to do it well.

David Fair: Well, it sounds like it's going to be an exceedingly busy couple of years and an exciting time of that. Thank you so much for your time today, Rebecca.

Rebecca Esselman: You're welcome, David. Thank you for covering the issue.

David Fair: That is Rebecca Esselman, executive director of the Huron River Watershed Council and our guest on Issues of the Environment. For more information on progress in next steps in the planned removal of the Peninsular Paper Dam from the Huron River, visit our web page at WEMU dot org. Issues of the Environment is produced in partnership with the office of the Washtenaw County Water Resources Commissioner. And you hear it every Wednesday. I'm David Fair, and this is 89 one WEMU and WEMU HD one Ypsilanti.

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