Dear Neighbors
FAQ Friday looks at one Frequently Asked Question each week. This week, the topic is "How about those spill gates?"
Background. Starting last summer (2019) and into the fall, we had our Technical Workgroup (composed of qualified community-based engineers, commercial builders, and other experts) look at this deeply for several months. As our folks and the GBRAs consulting engineers assessed the damage after the dam failure, it was clear that the dam took a huge wallop when it explosively failed on May 14, 2019. (Houses nearby shook from the boom!)
Bottom line, the concrete dam beneath the gates was found to be unsafe, and whatever gates were to be chosen, major repairs were needed for the 100-year-old structure before any kind of gate could be installed. It became clear by Fall 2019 that the main dam structure needed to be fortified, whatever gates were chosen.
Another important choice became apparent as we grew more knowledgeable about dams and dam technology. Stop logs are a ready-to-use way to isolate the spill gates on a dam for inspection or repair on very short notice. it greatly increases the safety for crews doing this work, and minimizes the costs of maintenance and repair. Almost all modern dams have them. If our dam had had stop logs when the dam broke, our lake would still have water.
Stop Logs. Stop logs are an easy way to seal off the dam and allow it to be maintained with a much higher margin of safety, without the need to remove the water from the lake; both factors greatly reduce maintenance costs. The stop logs are built along with the dam improvements, so they are always on-site and ready to be used on very short notice as needed.
PLDA’s leadership, its advisory board, and the GBRA are all in agreement that the most important option we want first is the ability to use stop logs. The Technical Group looked at the three spill gage options very closely, and given all the facts, they advised us that with stop logs, the costs for all spill gate options are virtually the same.
Once that decision was made, and the realization that the dam itself needed serious work, the choice of gates became secondary. The decision to use hydraulic crest gates was made based on which gates would be best for our dam.
Hydraulic Crest Gates. Hydraulic crest gates are a very reliable, proven spill gate technology that is used all over the US and the world. It is a workhorse design, durable, practical, and efficient, as well as safe and easy to maintain. Once the essential restoration work to the main dam structure was factored in that simply has to take place, plus the safety and lake-level stability that stop logs offer, the cost of any of the three spill gate candidates was essentially the same.
One source of confusion that persists is that the lower cost initially attributed to the bear trap gates was not realistic once the true issues with the dam surfaced. Of the $35 million estimated for the dam restoration, only about 10% ($3.6 million) is allocated to the actual gates, which will cost about $1.2 million apiece. The remainder is to ensure the core dam structure is sound and that we have stop logs.
The PLDA’s leadership, its advisory board, our skilled Technical Workgroup, and the GBRA are all in agreement on the engineering choices that have been made. All of us have looked at all the options very hard, and all are in agreement that the plans GBRA has made are based on the overall best choice of action available to us.
So who will own the dam? We had intensive discussions both internally and with our legal and financial counsel about the benefits and downsides of owning the dam. That was a complex choice and we spent a good deal of time learning as much as we could about the pros and cons before we made a decision.
In the end, the potential liabilities of dam ownership outweighed any benefits. GBRA will own, operate and maintain the dam as well as finance the construction and repair of the dam, oversee the repairs, and operate the hydroelectric facilities so as to maximize the gross revenues available to the WCID.
And there you have it! We're put a lot of work into it, and crest gates officially became part of the plan in Fall 2019.
One last announcement:
SAVE THE DATE!!
Boat/Float Parade in Support of Lake Dunlap Oct 3rd!!
We are planning a fun event in support of the plan to #RestoreLakeDunlap on October 3rd, and we want you to be part of it! Starting at 10 am and continuing till noon, we plan to meet at Schumann's Beach to assemble a boat parade of supporters that want to see the lake back. Everyone is invited. Graciously, the owners of the ramp at Schumann's Beach have agreed to let us use the "beach" and boat ramp as our base camp. We're very grateful for their hospitality! We hope to attract people from all parts of the lake to participate and to show support for the effort to bring our lake back.
It might not match the July 4th boat parades of old, but we hope to evoke that same spirit. Plan to bring your kayak, canoe, paddleboard, Jon boat, inner tube, floaty, party boat, or whatever you have for a leisurely cruise/paddle/float with your neighbors down the lake from Schumann's and back! Much more detail will be coming out ahead of that date, but we already hope to see you there! (Rain dates are Oct 4 and Oct 10)
See you there!