Commonsense Lock and Dam solution would be beneficial

TODD BENNETT/FILE Water from the Savannah River flows through the New Savannah Bluff Lock and Dam. Instead of de-authorizing the Lock and Dam, a plan similar to the already-approved 2012 fish passage would be quick and inexpensive to implement.

I grew up fishing with my father many years ago at the New Savannah Bluff Lock and Dam, and I have spent nearly a lifetime in engineering and planning for things that are dependent on its upstream pool – boat landings, docks, marinas, levees, flood studies, Riverwalk Augusta and the North Augusta Riverfront District redevelopment plan.

 

Like me, many in the Central Savannah River Area are deeply concerned about the recent federal legislation that de-authorizes the Lock and Dam and prematurely authorizes an in-stream “rock weir” in its place, as mitigation for environmental damage caused by the inner harbor-deepening project in Savannah 187 miles downriver.

In spite of considerable grassroots outcries to our congressional delegations in both states, Georgia’s two senators included an 11th-hour amendment to recent federal water infrastructure legislation (without consulting area stakeholders) that substitutes a rock weir for the Lock and Dam. The Georgia Ports Authority and the Savannah Riverkeeper advocated strongly for this outcome, notwithstanding the complete lack of engineering studies necessary to quantify and address the known documented risks created by these actions, and over the objecting voices of hundreds of area stakeholders – businesses, landowners, farmers, municipalities and concerned community citizens.

If adopted, the in-stream rock weir will create critical pool-control problems, flood impacts and other risks for Augusta and North Augusta.

Ironically, the project benefits commerce and navigation in Savannah, but does the opposite for Augusta. It would make our Savannah River navigable for fish, but non-navigable for man.

By de-authorizing the very structure that has provided a pool for the Augusta area, the law implicitly tables the already-approved fish passage around the Lock and Dam, for which an environmental impact statement (EIS) was approved by the affected federal and state environmental agencies in 2012, and which was estimated to cost $30 million.

If the Lock and Dam were rehabilitated in conjunction with the fish bypass, the total would be $50 million. This mitigation option was the only one that addressed the documented flood risks (by minimizing impacts to the five large floodgates) and maintained the water supply pool during and after construction. But that plan is now history – at least until the two new statutory alternatives are inevitably ruled out.

What is wrong with the two legislative choices?

Building a rock ramp over the top of the de-authorized Lock and Dam. This alternative, which eliminates the five floodgates, was closely studied in the 2012 EIS and included a mile-wide runaround spillway on the South Carolina side of the river to provide the flood-handling capacity that would be lost by placing the rock plug where the gates had been. This plan was discarded because of its estimated $100 million price tag, and because it resulted in the loss of pool during construction. If the plan should cost anywhere near that much now, it will be discarded again.

That leaves just one alternative:

Building a rock weir across the river upstream of the Lock and Dam and removing the Lock and Dam. This alternative scheme was originally proposed by the U.S. Army Corps of Engineers in a “value engineering” study in 2015 that positioned a weir 1,800 feet upstream of the dam “to minimize construction costs.” In their words, the concept would (emphasis mine) “maintain pool elevation within current range of operation … (and) remove the gate piers to sill.” The Corps’ preliminary study reported the cost of this value engineering proposal at $56.7 million, but included no mitigation for the loss of the five floodgates or for the loss of pool during construction.

In fact, the Corps’ own “internal reviewers had serious concerns” about the ability of the weir simultaneously to maintain the pool elevation and not to raise the flood levels upstream. Therefore, they proposed a somewhat different scheme late in 2016 – incidentally, after the flawed enabling legislation had already passed in the Senate:

The Corps’ newest “rock weir alternative refinements.” The latest Corps plan (dated Nov. 30, 2016) moves the weir 300 feet downstream to a point 1,500 feet upstream of the Lock and Dam, and describes it, again in their words, as (emphasis mine) “a fixed structure that allows the pool to be maintained near current levels.” They included a preliminary flood analysis that shows a small rise in the 100-year flood elevation upstream. But, they would accomplish that result only by lowering the everyday pool to unacceptably low levels. The normal pool level would be lowered by 3 feet!

Here is a classic example of “bait-and-switch.” To address the known flood risks created by the weir, the Corps, aided by the Georgia Ports Authority, has now abandoned their commitment and duty to maintain the current water supply pool level and instead now intends to drop the pool elevation by 3 feet or more.

Furthermore, the Corps has not studied the severity of any other flood flows (either those to be expected more frequently or less frequently) to determine their backwater effects in the greater Augusta area upstream.

So, it turns out that the weir scheme cannot simultaneously “maintain the pool elevation and not raise flood levels” as had been promised. No surprise there. That situation was factually demonstrated in the 2012 EIS.

Now we are left with a choice between two bad alternatives, neither of which addresses the entirety of issues that are critically important and threatening to the greater Augusta community and to the environment:

Loss of control of the pool to preserve and control water supply (residential, commercial and industrial), resulting in a significantly lowered normal pool elevation

Loss of flood control capabilities, resulting in more frequent flooding and property damage for ordinary floods, even assuming that the Federal Emergency Management Agency/regulatory 100-year flood remains the same

Potential changes in FEMA regulatory flood plain elevations, governing development near the flood plain

Loss of the pool during the period of construction, impairing municipal, industrial and military water supplies

Lowered everyday water levels, imperiling water-dependent uses, such as water intakes, marina facilities and individual docks, and probably ending important river events such as Half-Ironman swim, drag boat races, rowing regattas, etc.

Permanent loss of navigation, except for small craft such as canoes and kayaks

Serious environmental and practical impacts of the inevitable silting-up of the pool over time

Unproven and dubious success of the mitigation project for passing endangered sturgeon

These are the facts – and risks – that the Savannah Riverkeeper and some of our business and industry leaders are ignoring.

But it is not too late for our community to have a voice and to have these critical concerns addressed.

And fortunately, there is a good solution that addresses all of these risks and serves the goals of the harbor expansion: Adopt a commonsense plan similar to the already-approved 2012 fish passage. That would work quite well, when the Lock and Dam is simultaneously repaired to support it. Moreover, this plan would cost the least of all the alternatives heretofore proffered, and would be the quickest to implement.

Our municipal, business and community leaders need to come together to demand a fair and safe Savannah Harbor mitigation project – one that is mutually beneficial to all concerned and that does not irreparably damage the greater Augusta area.

(The writer is a consulting civil engineer, city planner and land surveyor. He lives in Augusta.)

 

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