news from the waterfront by Tim Matson
OUR POND: A HISTORY
One thing I encounter often in making pond evaluations is owners who don't have much idea of their pond's history, or put another way, its specifications. That can make it a challenge to figure out why the water level won't hold up, or why water quality is troubled, or if there's a drain for dewatering the pond to do repairs, etc. Since you can't see underground, we need some construction history to help analyse pond problems. Not long ago one owner of long duration had never seen where the spillway pipe discharged. A wild goose chase ensued in pursuit of the elusive pipe so we could determine if there might be a leak responsible for a low water level.
I'd like to make a case for pond owners and owner-builders to keep a ledger or diary: basically a record of important pond construction details and events in the pond's history. If you're building the pond from scratch it should be simple to keep track of important construction details. If you're living near the construction site, you'll probably be paying attention to what's going on already. Make sure the contractor keeps you informed of how he's choosen the site, so you know soil types and the static ground water level. If there's a dam, you should know how it's being built. Is there a good solid foundation or are there springs that need drainage. Is a core trench being built. Is the dam being built in compacted one foot layers, per best practice recommendations. Not only will this give you a good record of construction details, but it will demonstrate to the builder that you are paying attention. These details may be significant down the road in the event repairs are needed, or you are selling the property and can hand the new owner this valuable record of their newly acquired pond. If the property is a second home and you aren't around during construction, ask for a record of construction steps and if possible get the contractor to photograph significant building details. This should be easier than ever with the advent of smart phones. And if you're present during construction, take the shots yourself. You might think, well, I can remember all this, but some owners live with their ponds over many decades, and memories fade. Spouses pass on. Keep a record.
I was recently working on a pond that featured
a drainage system feeding into the pond from the upslope watershed. You could see the pipes entering the pond, but where they had been installed upslope was a mystery. Did the pipes need a cleanout? Might the system be enlarged to increase ground water supply? It was hard to determine with no plan to refer to. So, the choice was leave it be, or tear it up to find out. A pond history would have solved the question.
One of the first questions I ask a client regarding a pond evaluation is, what's the pond history? The following are some of the details that can be very useful in diagnosing problems or making decisions about repairs or improvements.
Was there ledge in the basin area or dam foundation?
This could have significant impact on future leakage problems. Since you can't see underground, a history would help, and maybe avoid having to drain the pond and look for ledge.
If there is a standpipe (riser) overflow outlet, does it have a drain coupled on? Surprising how many pond owners don't know. Over years sediment builds up and may disguise a drain if it's there at all. If there is a drain, it could be a source of leakage; and it's certainly not something you want an excavator to hit during a cleanout. Obviously, if there is a drain, it might come in handy if the pond needs dewatering. (But beware old corroded valves and gates which might break when opened, leaving you with a gushing pond and no way to easily repair an old rusty part without tearing the whole system out.)
A record of significant water events can be useful.
Has the pond always maintained its designed waterlevel? Were there any periods when water level dropped significantly? If water level drops were connected to dry weather, the weather could be to blame. But if the pond is subject to unusual water drops or if the water level is gradually declining over the years, there may be a leak or a loss of water supply.
How about bad algae blooms or invasive aquatic plants? If so, were they treated with natural water conditioners or chemicals, and to what effect? Or
perhaps there was a cleanout (dredge). These events and solutions should be recorded.
Another spec to keep track of is depth. If you build a new pond, what is the depth of the deep area(s)? And if you keep track of depth every few years, you can determine if sediment is building up. Sediment trending up might be leading to poor water conditions, and suggest the time will come for a cleanout. One alternative to mechanical dredging to restore depth is suction dredging, which can be less damaging to shore areas where excavators tear up the terrain as they move about. Suction dredging would not require dewatering the pond.
It can be very helpful to have contact information for the original pond contractor (or contractors who have done other work). That can lead to detailed construction information which might help in making decisions regarding pipe repairs, cleanouts, and
perhaps sourcing new water supplies. In addition to the original contractor, neighbors may be able to recall stories about the pond history; the same goes for the town office. Certainly in the case of a pond acquired from a previous owner, the past owner(s) may have useful information on pond performance, repairs, fish stocking, etc.
As long as you're keeping a ledger of significant pond details, why not include animal sightings and the comings and goings of various aquatic critters from fish to frogs to crayfish to various wildflowers and plants. I like to note when my pond freezes over and later the date of ice out. By itself the dates provide interesting data for the annual climate, and over a longer period,
it becomes possible to see larger trends, such as the ice cover that doesn't last as long as it used to. Your pond is a diary of climate change.
So, find youself a durable blank book and put it somewhere it won't get lost. As for a title, maybeOur Pond, A History. Or something more personal. If I recall correctly one fellow called his Walden.
Next month: More on keeping a pond history and tracing the history of a pond for purchase.
October 5, 2014