On March 21, Ohio Department of Natural Resources responded to public comments and questions regarding Grand Lake St. Marys, its treatment, and its future.
Participants: Scott Fletcher, ODNR
Dr. Harry Gibbons, TetraTech, Inc.
Greg Smith, Ohio EPA
Russ Gibson, Ohio EPA
Darla Peelle, Ohio EPA
This document is being generated to respond to comments made during the Ohio Department of Natural Resources’ applicant’s meeting, a requirement of Ohio EPA’s Water Pollution Control Loan Fund application process.
Comment 1: What is the goal of the demonstrations planned for April 2011?
Comment 5: How will dredging effect the alum treatment?
Response 5: Dredging will enhance the alum application. A benefit of dredging is the removal of nutrient laden sediments. It makes no difference whether the sediments have been treated or not.
Comment 6: Are we talking about an endless process of alum application?
Response 6: Managing nutrient levels in a lake is a long-term process. Treatment may require many years to reach a point where the level of nutrients has been reduced sufficiently to make a significant difference. The amounts of nutrients that continue to enter the lake are also an important factor when determining how long treatments may be needed.
Comment 7: The whole lake application will provide 17 percent of the dose needed to inactivate the phosphorus in the lake. Is there a reason, such as toxicity, that the dose is not 100 percent of what’s needed?
Response 7: There is no toxicity issue related to alum. The approach being taken is incremental. The funds that are available have a bearing on how this project is structured. The fact that nutrients are still entering the lake from the watershed also indicates that an incremental approach be used. Over time, after the initial applications are done, it will become easier and less expensive to inactivate the remaining phosphorus in the lake. As indicated earlier, this is only the beginning of a long-term effort.
Comment 8: There are other chemicals used to inactivate phosphorus such as ferric chloride and ferrous sulfate. Why are those not being considered?
Response 8: Ferrous compounds are susceptible to oxygen reduction in the sediments. Eventually, a ferrous bond would be broken down by nature and the phosphorus would be released into the lake again.
Comment 9: Will funds be available through the WPCLF in future years for treatments of the lake?
Response 9: Several things have a bearing on whether funds would be available again through the WPCLF. Determining whether this project is successful is one factor. Another factor is that 2011 is the first year in which a WPCLF loan principal may be forgiven. The forgiveness is authorized through the appropriation process at the federal level. We cannot predict whether that authorization will continue. At this time, the WPCLF has sufficient funds to meet all requests. We expect the demand for forgiveness to increase if it continues. Like any pool of funds, if the loans are made and forgiven, the funding pool will shrink.
Comment 10: How long will it take to fix the lake?
Response 10: It depends on how much of the external load from the watershed is being controlled and how fast. Depending on the dose, you may see effectiveness last for two to 20 years if the incremental approach is continued. It is impossible to accurately predict how long the effectiveness will last.
Comment 11: In 2009 and 2010, Ohio used World Health Organization (WHO) standards for one toxin and had no standard for the others. I believe that the standards for algal toxins should be adopted in Ohio rule or law.
Response 11: The Ohio Department of Health is investigating standards for human health risk for algal toxins.
Comment 12: Will Ohio use WHO standards for future years and issue advisories based on that standard?
Response 12: Until the Ohio Department of Health determines state standards, the WHO standards are the only ones available.
Comment 13: Will the alum dose planned for this year be a permanent reduction for internal loading of phosphorus in the lake?
Response 13: Not entirely. This application will not reduce the in-lake phosphorus by 100 percent.
Comment 14: Can you offer an estimate of what the lake will look like in terms of years? Will this application of 17.6 percent of the alum needed return the lake to a state that we saw eight to ten years ago?
Response 14: It is impossible to predict results in those terms. This limited dose may provide several years of effectiveness, but it is the first of several that will be needed.
Comment 15: Does the use of hydrogen peroxide change the dose of alum needed?
Response 15: The dose of alum is determined by the amount of phosphorus that is present. The hydrogen peroxide is used to allow that alum to effectively bind with the phosphorus rather than the organic matter in the water column and sediments. The hydrogen peroxide is meant to make the application more effective.
Comment 16: How do the liquid alum and granular alum applications compare?
Response 16: The liquid alum in the demonstration is dosed at the full rate to inactivate the phosphorus. The granular alum is dosed at a rate to strip the water column of phosphorus, but not affect the sediment phosphorus. The granular product is demonstrated to show the utility of small, localized areas. In the demonstration the granular alum is dosed at a rate twice as high as the liquid alum planned for the water stripping portion of the whole lake treatment. We expect to see results from the granular application.
Comment 17: Considering that the watershed feeds into the lake from the south and the prevailing winds are from the southwest, wouldn’t it make sense to make application to the south and west portions of the lake?
Response 17: The doses for the mid-lake area were determined based on sediment core samples. These samples helped us to characterize the lake and find the highest concentrations of phosphorus. In order to maximize the effectiveness and longevity of the treatment we have targeted those areas.
Comment 18: If we do not make an alum treatment this year are we very likely to see algal blooms again? Conversely, if there is an alum treatment this year will it greatly reduce the likelihood of algal blooms this year?
Response 18: Without an alum treatment it is highly likely that harmful algal blooms will be seen. An alum treatment does not offer a guarantee that there will be no algal blooms this year, but any blooms that form should be less intense and shorter in duration.
Comment 19: Would dredging the lake deeper help solve any of these problems?
Response 19: If dredging were to be a highly effective tool, the lake would have to be dredged to a depth whereby it could stratify. That would mean dredging to a depth of 20 feet minimum, preferably 60 feet. Anything short of that depth would not yield a difference. Even if the lake were dredged to that depth, external loading from the watershed would need to be dramatically reduced. Even at a 10-foot depth, the same nutrient recycling issues would exist as they do today.