Pondology
news from the waterfront by Tim Matson

FILL ‘ER UP!
REFLECTIONS ON THE 2010 POND SEASON

Looking back on the 2010 pond season, it was
an active year with a significant number of people moving forward on both new pond projects and repairs/cleanups. That rather surprised me, considering the shaky economy. But as one collegue observed, “I think people are spending on ponds because you get a lot of bang for the buck.” And as far as repairs go, it’s not wise to put them off for long because weed infested ponds or deteriorating dams/spillways raise fears of killing the pond off, or perhaps a dam blowout and havoc downstream.

Another reason for strong pond activity was that it seemed like a buyers’ market, with contractors lowering costs to compete for work. I saw more than one job come in for almost 50% less than it might have cost a few years back. To get those good prices often means property owners spend more time vetting contractors and researching the project; doing your homework also gives you confidence that money is spent as wisely as possible.

Many projects presented challenges that fell into traditional categories. On the repair side, I saw a lot of disintegrating or defective overflow pipe systems. Owners had to make decisions about whether to replace entire riser/discharge piping, attempt partial repairs, or perhaps remove old systems entirely and revert to earthen overflows, to cut costs. Making these decisions can be tricky because once a steel pipe system starts falling apart, patching it is not simple. Some contractors may suggest sliding in a new pipe and using concrete to fill the gap between old and new pipe. The risk is that as the old pipe continues to rot, water may leak around the outside of the pipe and through the dam. There is also the question of how much new pipe to insert. If you just “fix” the standpipe, the discharge pipe (while perhaps not as badly rotted) is going to continue to corrode, presenting a continuing risk of undermining the dam. I’m oversimplifying this problem, but it’s worth mentioning even superficially, because I’m seeing an increasing number of rotting pipe systems. This is because a lot of ponds were build in the 60s and 70s, and the steel or iron piping is now past its lifespan. I expect to see a lot more of these in the coming years.

The dam situation gets even more complicated if owners have allowed trees to grow up on the embankment all those years. Thus, dam rebuilds or reinforcement is becoming a common topic, too.

Another common problem was water shortage. For both new ponds and old, many suffer predictable supply shortages; or new supply issues due to any number of reasons: new leaks, loss of water supply (we had a drought in the northeast that magnified that situation); pipe failure (already discussed). So, there were many pond owners looking at ways to supplement water supply or reduce soil infiltration. In the case of new ponds, where water supply looked
poor, as much attention was focussed on finding
water as on pond design. And in several cases,
it became clear that the best prospect for a full
pond would require a membrane liner.

I saw more than one client nix a project when it became clear that a liner would be needed. Some people just don’t think plastic and pond belong in the same sentence. Others are wary of liner durability, or the design criteria suggested for
liner preparation (underdrains; flatter sloping;
protective underlayment/cover, etc). But the fact is
that an increasing number of contractors are becoming proficient at liner installation, and prefer it to the uncertainties of clay.

I was surprised at the variety of approaches to liner installation I saw. Opinions on the need for
underdrains varies (especially depending on projected ground water conditions); criteria for slope design varies; contractors also have different
opinions on the need for protective covering.
All this adds up to more head scratching for the prospective pond owner, and frankly I heard myself
more than once falling back on that old bromide,
“pond building is a gamble.” And it seems like the
more you want to reduce risks, the more it costs.

 



Here’s another trend I saw confirmed: existing ponds have gained in value. Because of the permitting hurdles in many potential pond sites, and the general expense of new construction, someone with an existing pond has a real treasure, even if it’s overgrown with weeds and has a leaky pipe. Why? Because it’s grandfathered in, often
in a site where pond construction would not be permitted today (usually wetland issues); and much more costly to build now than 30 years ago. So, it’s worth keeping that old pond maintained.

I get a number of calls from prospective home buyers and real estate agents to evaluate existing ponds. What are the pros and cons of this pond? How much work does it need? Can I raise fish here? Would installing a hydrant lower insurance costs? How can I get more water supply? Etc. A number of property sales sink or swim on the pond report card.

In addition to dealing with the traditional challenges of pond construction and improvement/repair, every year I learn a few new pond techniques that help keep the work intriguing.

For instance, one troubled pond I ran across had a serious leak problem. Luckily the owner had access to a stream, and was able to set up a pump so he could refill the pond before every weekend visit.
The problem was that the hose filling the pond was
eroding a gully in the side of the basin as it filled the pond. A contractor I know gave me this tip: attach the end of the hose to a float, and tie the float to the opposite bank so it stays in the middle of the basin. No more erosion.

Saavy test pits. Here’s a tip I hadn’t heard before. When test pits are suggested at start of a pond siting process, it may be convenient to have them dug by a local contractor who may not necessarily dig the pond. If the test pits are to be left open for later inspection by a more qualified pond builder, it may help to separate the soil into two piles: first the topsoil, then the subsoil. That way the pond builder can see what sort of soils, especially subsoil, lie below the water in the test pit. And if the test pit gets refilled, you can put the subsoil in first, then top off with topsoil, for best regrowth of grass. Otherwise you often wind up with a mixed-up mess of soils difficult to “read” and if refilled, topped off with subsoil that won’t grow a blade of grass.

Fish Tale. A lot of my clients like the idea of raising fish, but they know that with predators aplenty, they’ll probably be restocking regularly. I thought I knew most of the ways fish disappear, including to bad water and oxygen, but a friend of mine added a new one this year. He’s a trout farmer, so he hears lots of stories of mysteriously disappearing fish. One of his customers just couldn’t figure out why he was losing so many fish.
Must be herons, he said. Louis took one look at the pond and shook his head. They’re going down your standpipe. No way! the pond owner said. Louis replied, without a trash rack they’re jumping down the pipe. The guy refused to believe it, and as I listened to the story I tended to agree. I see a lot of ponds with open standpipes and no one ever mentioned standpipe escapers. Well, Louis said, let’s try an experiment next time we stock. They dug a small pool where the pond outlet discharged, and sure enough a few days after the next trout stocking, the pool started to fill with fish. Did I mention that my friend has a specially designed trash rack that will keep in fish without plugging up with debris?

Two for One. I worked on a couple of old, overgrown ponds needing cleanouts, standpipe replacement, and dam repairs. Because these ponds  were each fed directly by a sizeable stream, and included on the upslope end much wetland territory, there was concern about how to make the updated pond resistant to sediment loading and renewed encroachment of the wetland area. Perhaps a silt pool? However, it looked like silt pools would load up quickly and need frequent cleanouts. In the end, I proposed for each pond creating two ponds. The upper pond would work as a large silt pool and include wetland assets the owners valued (plant life, critter habitat), while the lower pond would have relatively sediment free water for good swimming and general recreation/landscape assets. It can be a pretty big conceptual leap for pond owners to start thinking about repairs turning one pond into two, but in both cases these two-for-one proposals received very positive reception.

January 21, 2011

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