Dam Maintenance Project
Week 10 Update: 26 November 2020
The YLPA Dam committee is pleased to report that the State-required maintenance work on the dam has been completed.
We have informed the New York State DEC that the work is complete, and we are awaiting their final inspection and approval.
Smoothed Channel with 16 Inches of Flow
The cofferdam has been removed, and the outlet channel already has 16 inches of water, while maintaining downstream flow to the Pine Kill. The lake is steadily returning to the normal winter level, however slowly, since we have not had much rain.
Cofferdam has been Removed
In addition to the State-required work, we have also created a new protective grate over the outlet channel.
New Protective Grate in Place
We are currently in the process of improving the internal workings of the walkway platform, access stairs, and stop-log lifting system.
We will continue to perform these improvements, as well as other maintenance and repair work, as the weather permits.
New Interior Walkway Under Construction
You will be happy to know that the dam and outlet channel are now in better shape than they have ever been before.
We wish to thank all our members who made donations towards this work. We are pleased to report that we are within the budget provided, with the help of many, many volunteer hours, as well as loaned equipment.
Have a great winter.
Maintaining Flow into the Pine Kill
Week 7 Update: 8 November 2020
The YLPA is pleased to report that the patching and smoothing of the dam’s outlet channel is now complete.
We had previously sealed all the openings at the inlet and since then have been patching, repairing and smoothing the entire length of the channel.
In the photo, you can see the before and after smoothing.
In addition, we have also replaced the protective timber grating which had deteriorated.
During the work process, the downstream flow to the Pine Kill was maintained via pumping over the top of the dam.
When the pumping is discontinued, the downstream flow will be maintained via the new channel.
We have some minor work to complete inside the channel, however are now scheduled to remove the cofferdam on or about November 17.
The lake has already begun to refill. Once the cofferdam is removed, we will monitor the outlet regularly to allow the lake to rise steadily while maintaining the downstream flow to the Pine Kill.
The work has been performed within our targeted budget, thanks to all the volunteers and donated services.
We are very pleased with the results of this project, and will prepare a slide show for presenting to our members at the Annual Meeting planned for the Memorial Day weekend of 2021.
We wish everyone happy and healthy holidays and a safe winter. See you next year.
Week 5 Update: 25 October 2020
The dam project continues to make very good progress and we are in the final stages of smoothing the concrete spillway.
The pictures show how rough the channel is after chipping, and the first step of the smoothing process.
We have discontinued pumping from the lake and are currently maintaining the downstream flow to the Pine Kill with water from inside the cofferdam.
We anticipate finishing the project in approximately two weeks. Removal of equipment will then take place.
Overall, the project has been a tremendous success. We look forward to providing a complete update at our Annual Meeting in May. Have a safe winter and let’s hope for some much needed rain at the lake!
Week 4 Update: 20 October 2020
Great news! We have accomplished the first and most important task of significantly reducing the seepage at the outlet chamber by plugging the low flow pipe and lower outlet chamber with concrete. We are in the process of lowering the upper spillway at the outlet channel, which will greatly improve the flow capacity and allow better control of the lake level. Since the original concrete is such high quality, the process is slower than anticipated, which is good news for the strength of the dam, but bad news for the time it takes to remove.
As you can see by the photos, the crew is now squaring off the sides and bottom. (Almost there!) It’s not pretty yet, but it will be when we are done. It is very important to have a smooth surface for the water to flow, but the original outlet channel was so rough that it did not flow properly. We anticipate that the chipping will be done by the middle of this week. After that, we can make the remaining necessary repairs and start to apply the smooth surface for the channel. We hope to finish the channel cutting and smoothing in the next 2 weeks.
We also must replace the protective grate on the front of the channel inlet before we remove the cofferdam. We had the measurements taken, and are working on building the inlet grate. The grating is not only important for boating safety, but will also prevent driftwood from blocking the channel. When we dewatered the inlet channel we had to remove a waterlogged piece of driftwood about 5 feet long.
We have removed the large pumps and will begin allowing the lake to refill outside the cofferdam. We will maintain pumping inside the cofferdam as required for the remaining work to be performed. We will keep the members informed of the progress each week.
Week 3 Update: 11 October 2020
Your Dam Committee is pleased to report that we have accomplished our main goal of sealing the outlet chamber to strengthen the structure and limit future leaks.
This was our main concern and we did not know exactly what to expect when we lowered the lake and set up the coffer dam.
After a few days using vacuum excavation and cleaning out this area, which has not seen the light of day for at least 50 years, we found a section of what may have been concrete which had completely decomposed into gravel.
We were able to locate and thoroughly clean out the bottom 15 inch pipe and prepare it for grouting and place additional new concrete to seal the area that was allowing water to seep through the dam for decades.
We also found that most of the concrete used in the spillway was very good quality concrete which we tested and found to be more than double the strength of most of the concrete in everyday applications. The photos show 1) the outlet chamber and pipe, 2) cleaning of the pipe and 3) final view with new concrete.
Now that this very important portion of the work is complete we can continue with the next task of lowering and smoothing the main outlet channel and restoring the protective grate at the spillway.
We are very grateful to all of the members who are contributing to the dam fund as well as those who are positive and encouraging our team to make these necessary maintenance repairs which will last for many years to come and allow us better control over the lake level. This means being able to better handle storm events and keep the summer height of the lake level further into the fall.
Thank you for your support!
Outlet Chamber and 15-Inch Pipe (Foreground) During Debris Removal Vacuum Excavation Underway New Concrete Has Been Poured
Week 2 Update: 3 October 2020
The dam committee is pleased to report that the lake has been lowered sufficiently to allow the safe installation of the cofferdam. The committee apologizes to the year-round residents for the pump noise, but the lake simply was not draining fast enough for us to insure that the entire project could be completed, and the cofferdam removed, before the first freeze. We are going to need these pumps to maintain the lake level following heavy rainfall, as well as to maintain down stream Pine Kill flow, as required per DEC permit requirements. We are well aware of the inconvenience and are working as fast as we can to minimize the costs and duration of the project.
We are currently at the point where we have created a dry enough condition within the cofferdam to allow us to begin our work within the outlet structure. We can see that there will be quite a bit of clean up within the outlet chamber before we can evaluate exactly what will be required to finish the necessary maintenance work. The contractors will be on-site between Friday 2 October, and Monday 5 October, to have a look at the conditions and also to better understand the details as to how the work must be done.
Due to the fact that we could not have a face to face meeting with the lake members this year, we were not able to hear, and address, the member’s concerns regarding this project. Be assured that our dam committee consists of a team of licensed professional engineers and multi-generation lake members (with contracting experience), who volunteered to help in any way possible because of their strong love for the lake, and commitment to seeing this work done properly. We are determined to get this done in the safest and most expeditious way possible. In that way we will also minimize costs. We have heard concerns regarding the fish, whether the water level will drop even more over the next few weeks, concern for water wells and ecological management.
Regarding fish and wildlife: The lake is large enough, and deep enough, to maintain a safe environment for the fish. However, the fish also want to know what is going on. In fact there were several curious fish swimming around while we were installing the cofferdam. There was a turtle and a bald eagle who also made a visit. You will be happy to know they were all doing fine.
Regarding well levels dropping due to the lake height: The lake is currently not much lower than the normal winter level, and lack of rain would have a much more significant affect upon a water well than the current lake level. Remember, the lake does not provide water to the surrounding area, the surrounding area provides water to the lake.
Regarding ecological management: Rest assured that we submitted the necessary permit to the New York DEC and have obtained their blessing to proceed with this work. We are adhering to the DEC requirements, and one of them includes maintaining the downstream flow, so that is another reason for the large pumps. While we also do not want to see the lake level drop any further, the requirement to maintain down stream flow means we need to keep a close eye on what amount of pumping is enough, but not too much. While we wish for rain to maintain the lake level, too much rain will slow our work progress. That is one area we have no control over.
The board members and dam committee would like you to know we are as much, or maybe even a bit more, concerned about getting this done correctly. We know we have this one chance, and have been planning this for at least two years. Some members have come to us with ideas they have had for many years. We ask that you understand and maintain a safe distance from the work area at all times. We also want you to be aware that the current outlet channel will be smoother, and therefore flow more efficiently, and ultimately allow us better control over the management of the lake level in future years, which then will allow us to keep the summer lake level longer into September. We will keep you informed of our progress.
Week 0: Dam Maintenance Work Set to Begin
After many years of preparation and coordination with State officials, the time has finally arrived for our long-planned maintenance of the Yankee Lake Dam. Our dedicated Dam Committee reports that:
1. Professional grade pumps will arrive in late September. These will be visible, audible, and will be used, as needed, throughout the duration of the maintenance project.
2. The “Portadam” brand coffer dam is due to be delivered and installed during the week of 28 September. It bears repeating… do not approach anywhere near this coffer dam. Any breach of the coffer dam or the lakebed surrounding it could cause life-threatening harm to those working on this project. Trespassers will be prosecuted.
3. A security camera has been mounted to monitor the site 24 hours a day, 7 days a week. Signs advising of such have also been posted.
4. As the project progresses, you will likely observe a collection of mechanical equipment up on the dam. Do not be surprised or alarmed. This is an intensive and highly technical project. Expect to see industrial pumps, a crane, cement trucks, and other professional vehicles.
5. The low lake level offers a unique opportunity to do repairs at your lake front and to clean up the lakebed around your property. We encourage all to get out, take a look around your lakefront, and clean up any debris or trash that may have floated in. This is especially true around the island. Your support in this work would be greatly appreciated!
6. As a reminder, the stumps and submerged logs are the “bones” of our lake. They are a critical part of the lake ecosystem. You are never authorized to cut, move, or remove any stump or log without prior written approval of the YLPA Board of Directors.
7. In the interest of reducing the number of “blast emails” sent to members, from this point, until conclusion of the project, updates will be provided here on our website.
8. Finally, as mentioned in past communications, we will be spending down the “Dam Fund” that we have so prudently saved over the years. If you are in a position to help replenish this fund so that we are in good standing should any future unplanned work be necessary, we’d be most grateful to receive such a contribution. The form below has associated controls that will allow you to download and print a PDF version of the form for you to fill out and send to us. Checks should be made payable to “Yankee Lake Preservation Association” (the bank insists this be spelled out, not abbreviated), and mailed to:
Yankee Lake Preservation Association
C/O Brad Dawkins, Data Manager
143 North Shore Drive
Wurtsboro, NY 12790