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New dam study recommends two more feet of water

COLUMBUS – A hydraulic evaluation of the Buckeye Lake Dam commissioned by the Buckeye Lake Region Chamber of Commerce found that the Dam meets recommended “stability factors of safety” at a 890.75 lake level.

That level is two feet above ODNR’s new definition of winter pool of 888.75, two feet, three inches above Wednesday evening’s lake level of 888.50 and just one foot below normal summer pool. Boaters would be able to navigate the lake and most canals, with caution, at that level. It would also make ODNR’s dredging operations easier and ease removal of some docks on the earthen dam.

Rizzo Associates of Pittsburgh conducted the study that was funded by the Chamber, several other lake-wide nonprofit organizations, homeowner associations and private donations. ODNR contracted with Rizzo in 1997 to assess the Dam’s ability to retain the probable maximum flood (PMF).

The U.S. Army Corps of Engineers (USACE) assessment released in March included a review of earlier engineering consultant reports. On Rizzo, it stated:

“Paul C. Rizzo Associates, Inc. (1997) concluded that the dam crest could be raised an additional two feet without compromising embankment stability. This determination was established by field observations, subsurface explorations, laboratory testing, piezometer and observation well data, evaluations, and stability analysis. The consultant conclusions were based on limited information and on the assumption that house foundations built into the embankment would not contribute to failure. This consultant also stated, without the opportunity to obtain additional hydrologic and hydraulic data, analysis, or modeling, that raising the embankment crest to elevation 896.5 feet to retain the PMF would only marginally affect discharge and flood related impacts downstream of the SFLR (South Fork of the Licking River).”

President/CEO Dr. Paul C Rizzo, P.E. made a PowerPoint presentation of the study Tuesday afternoon to a group of ODNR managers and to several USACE officials via conference call.

ODNR participants were: Fred Shimp, Assistant Director; Gary Obermiller, Deputy Director for Parks and Watercraft; Mark Anthony, senior policy advisor; Steve Berezansky, special projects lead; Hung Thai, Engineering Division Chief; Rodney Tornes, Soil and Water Division Assistant Chief (responsible for Ohio Dam Safety Program); and Jeremy Wenner, Engineering Division project lead. Steven Porter, USACE’s assessment project manager and several engineers participated via conference call.

Chamber President Tim Ryan and Chamber Secretary Tim Figgins accompanied Rizzo to the meeting. Ryan told The Beacon that there were a lot of questions and interaction from both ODNR and USACE during the presentation. He characterized their initial response as noncommittal.

The study’s executive summary lists five recommendations for interim Risk-Reduction Measures to increase the safety of the Dam:

• Modify the Sellers Point Spillway by lowering the crest to EL 890.75. (The crest is the lake level that is even with the height of spillway wall; higher levels of water will pour out the spillway). This modification will significantly increase the discharge capacity of the Spillway during flood conditions and allow the Lake to pass a larger percentage of the PMF than the current plan of lowering the Lake EL 888.75 with no spillway modifications, thus reducing the risk for a dam failure and making the Dam safer.

• Maintain the Lake at EL 890.75 (one foot below normal summer pool) until the remedial construction of the Dam is complete.

• Identify and strengthen specific vulnerable locations on the Dam by installing sheet piles, modifying the crest or downstream slope, or making other modifications as required.

• Perform a formal Potential Failure Mode Analysis (PFMA) with representatives from ODNR, USACE, Buckeye Lake State Park and independent dam engineering consultants. Prepare an interim surveillance and monitoring plan for the Dam aligned with the Potential Failure Modes developed during the formal PFMA session.

Chapter 14 of the Federal Energy Regulatory Commission’s engineering guidelines for a dam safety monitoring program defines Potential Failure Mode Analysis as “an exercise to identify all potential failure modes under static loading, normal operating water level, flood and earthquake conditions including all external loading conditions for water retaining structures and to assess those potential failure modes of enough significance to warrant continued awareness and attention to visual observation, monitoring and remediation as appropriate.” USACE did not conduct one for its March assessment report.

• Proceed on a design/build basis for remediating the Dam. Utilizing a design/build project delivery method will minimize the economic impact to the businesses and residences at the Lake by “fast tracking” the design and construction schedule.

The executive summary concludes, “The Risk-Reduction Measures described above will make the Dam safer by:

(1) reducing the risk of failure due to overtopping during a flood and

(2) reducing the risk of failure by strengthening identified vulnerable areas.

Further more, the recommended Risk-Reduction Measures will result in a safer Dam during the design and construction time period than the current plan of lowering the Lake to winter pool without any other modifications.”

The summary explains that ODNR regulations require a Class 1 Dam, which Buckeye Lake has been designated, to be able to pass a PMF flood without overtopping. The current plan of maintaining the 888.75 winter pool without any spillway modifications will only pass 55 percent of the PMF compared to 58 percent after lowering the Seller’s Point Spillway to 890.75 and keeping the lake level at 890.75 as well.

While the Rizzo study represents the first good news since March 1, it is too early to celebrate. First, how long will it take ODNR to evaluate Rizzo’s interim Risk-Reduction Measures? ODNR could reject them all or in part; or ask for additional analysis or modeling. ODNR might want the Potential Failure Mode Analysis to be completed before agreeing to increase the lake level above 888.75.

Then there is the question if there will be enough rainfall to raise the lake level two feet, three inches. Even if ODNR would agree next week to raise the level, we are fast running out of the typically wetter spring days into the generally much drier summer.

Of course, every day that passes without ODNR approval increases the likelihood that there won’t be enough precipitation to appreciably increase the level of the lake. As temperatures increase, evaporation will be pushing water levels even lower.

Dr. Rizzo will be talking about dam safety in general at the Chamber’s Full Pool Breakfast set for Friday at the Buckeye Lake Yacht Club. Copies of the final full report are expected to be available next week.

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