FOBC received a headsup a few days ago about a large “slide” on the downstream face of Lake Petit Dam (down by the ballfield). It is in the area that the large “gravel patch” was. First a little history, then some analysis & commentary.
History. A few years back FOBC was doing a routine inspection of the Dam, and noticed water seeping out of the side of the dam. The POA poopoo’ed it… no biggie. Videos were passed on to Georgia Safe Dams. They were concerned enough to move very quickly, and the POA was forced to get Geosyntec out to evaluate, and then the area was dug out, geotextile fabric laid down to hold back soil, and then the area covered with gravel. As part of the recent “Huge French Drain” work on the backside of the Dam, that gravel was repurposed, and then the area covered with dirt and reseeded. The premise was that the “french drain” would alleviate water pressure. That patched area has now slid off in a large section, and there is some erosion all across the lower portion of the dam, but especially in that right lower side (as viewed from the Ballfield).
Analysis/Commentary:
I won’t get to far ahead of GA Safe Dams on this one, but the fact is that this area is known to have high water saturation, and a high “phreatic line”. The phreatic line is the water table line under the surface of the ground. In this area… the phreatic line is actually right at surface level. The reason GA Safe Dams forced the POA to move so fast last time is because IF (that is an “IF”) water flow were to increase out of the face of the dam… then that is a pre-sign of failure, and the beginning of “Piping”. Piping is when water flow picks up and carries away soil. The process increases the flow diameter, and it becomes a reinforcing process (soil carried out by flow, increases flow, increases soil washout, etc etc until you have a rapidly increasing “hole” that begins to enlarge). Once that piping starts it is very difficult to stop, AND it can progress very rapidly. That almost always ends in the collapse of a Dam, and is one of the primary mechanisms of Dam failure.
So we have what appears to be an issue. It seems like the “gravel bandaid” was only superficial, and the actual problem was just covered up. GA Safe Dams is aware of the issue. The POA has not peeped a word, which is in keeping with their policy of absolute Non-Transparency.
So a few things in conclusion:
1) Unless magic fairies fix this… we are looking at even more unbudgeted money (that we don’t have). I am going off the top of my head here, but I think I “heard” from a 2nd hand insider source that the last “Gravel Bandaid” cost us about $100K+/- (I do know it was “part” of the $468K RipRap Project). Of course, the POA would know exactly how much it cost, but, well, you know… there’s that pesky “we’d have to share actual accounting data with the Property Owners” thing involving Non-Transparency.
(2) I said this years ago and it bears repeating… this is an OLD earthen dam that is already past it’s official 50 year lifespan. One of the things about Dams is that there can be stuff going on inside that you just don’t know about… until it surfaces. Like voids and channels of water deep inside that have been developing for decades. You don’t know it is there until water pops out somewhere, or you start getting wet spots on the downstream face. When it starts really getting bad it evolves into mud slides along the dam.
(3) I’ve thought long and hard about how to present this in a way our Big Canoe Property Owners can relate to, and understand… and I will try as follows:
Big Canoe has a generally older, and aging population — and Lake Petit Dam is a generally older, and aging Dam. Both Humans and Earthen Dams have predictable lifespans. Depending upon “Personal Maintenance” and “Lifestyle”… that predictable lifespan can vary significantly to the individual Human, or Dam. Lake Petit Dam has a documented history of an attrocious maintenance lifestyle.
As humans get older, we start to see physical changes. Sometimes “the plumbing” stops working as regularly (i.e. replacement of the LLO Pipes currently occuring). Knees and Hips can need replacing (i.e. the recent Drainage system, and the upcoming Spillway). But one of the last stages of irreversible aging is unfortunately the visuals of bruises and sores that don’t heal like they used to. Often it is in a localized spot at first, but once these things start happening, it unfortunately often spreads. This is an unpleasant image for many, but deep down we realize it as part of life (and eventual death). It’s the cycle of life in a human.
The wetspot in Lake Petit Dam was localized, then we had a gravel bandaid, now it is back and even worse. The wetspots are increasing lower down the face of the Dam, near the ballfield road. The new “French Drain”, like cosmetic surgery, appears to already be failing to stop the visual progression of age.
A closing, and somber moment of reflection… sometimes we just get to the point that all the additional surgeries, replacements and procedures become predictably too expensive, and invasive, and we (and I say we because it is the fate of us all eventually) … we reflect, and hopefully find peace in a good life, and gather our loved one’s and simply enjoy the time we have left… as time inevitably marches towards the last act.
Lake Petit Dam has brought this community some great memories. But the writing is on the wall, and there is only so much money that can be thrown at this. And the POA won’t even disclose how much we have yet to spend, and is about to take us farther and farther into debt on a course of action that may not get us where we want to go, or even fix the ultimate problem.
Nothing lives forever. I think it is time to ask for a second opinion, and some absolute transparency.
Peace,
– david / publisher / property owner
Focus on Big Canoe, GA
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