Pond Boss Forums POND CONSTRUCTION Selecting a site Possible New Pond in Maine

Hi everyone,

My wife and I are in the ‘preliminary thought phase’ about constructing a small pond on our property in Alna, ME. The land is around 46 acres, about equally divided between woods and fields, and includes a small section of tidal marsh. It has a ca. 1795 Federal Period cape house, which we have been gradually restoring over the past several years (as budget permits). The property backs up against a small tidal stream that empties into the Sheepscot River, so we have kayak access to the ocean (if so inclined). However, the stream is a long way from the house and the path goes down a steep slope...maybe a 15-minute walk in each direction...so we’d like to have some kind of water feature much closer to the house, hence the pond idea.

The water source for our envisioned pond is a year-around flowing spring that also supplies the well for the house. There is a natural, tree-lined drainage from the spring area, with solid-looking banks. I believe that creating a nice pond should not require much in the way of excavation beyond constructing a dam at a narrow spot between the existing banks of the drainage. We have a lot of fine clay in the soil that would ‘probably’ prevent much seepage along the banks and bottom of the drainage, but more soil tests are in order to confirm that. If we need to apply more clay, we have several local sources. We also have access to a lot of rocks if it turns out that some riprap might be useful. We'd rather not use riprap unless necessary, since we'd like to preserve the natural look of the drainage.

I’m estimating that the pond would probably be about 250’ in length, while varying from 20 to 60 feet in width, and up to 12 feet in depth at the dam end. When I have time, I plan to dust off my theodolite and do a bit of surveying to create a detailed plan and elevation diagram.

The spring’s flow doesn’t seem to slow down much in the winter. There is enough upwelling water to melt any snow that hits the ground in the marshy area immediately around the spring. However, the pond would certainly ice over...probably getting over a foot thick...so the pond would have to have an appropriate level control system that would draw water from several feet beneath the ice. I haven’t given the system design much thought yet, and have only begun to do a bit of research. I’m open to suggestions as to what approach would work reliably in sub-zero temperatures and allow the water to flow through the pond under the ice. Drifting snow is also a possibility to contend with.

I have not yet measured the actual GPM flow from the spring area through the existing drainage, but just to give you a very rough idea, if you were to channel all of the water into a single narrow groove, I get the impression that it might be comparable to running three or four ordinary garden hoses simultaneously. Of course that's not scientific, and I plan to take ‘real’ measurements of the flow at intervals over the next year or so. The pond itself would be located far enough downstream from the spring and the well that it should not have any effect on the dynamics of our domestic water supply.

I haven't even thought about the possibility of stocking the pond with any finny friends yet. That may or may not come later.

I’ve chatted a bit (unofficially) with the Maine DEP, and my initial impression is that our site meets the necessary criteria for being allowed to construct a dam and form a pond. I would, of course, double-check everything, have the DEP conduct an official site visit, and obtain approval in writing from any applicable organizations.

The next time I’m in Alna I’ll plan to take a few photos of the spring area and the drainage to post on the forum. I generally only go up to our Alna property when I have time to work on the house or in the fields. We are currently living in Brunswick, ME while we’re restoring the old house in Alna.

We're open to ideas. Thanks.

Welcome to the forum! If your plans meet the DEP requirements, your local NRCS agent at the USDA off ice should have drainage ideas for you. If wanting fish in an area that will get a foot of winter ice, I'd consider increasing the depth to around 14' for a substantial part of the pond to avoid winter kills.

My first thought for a spillway pipe would be similar to a bottom draw system, but with a vent near the back side of the pond with a critter guard so the crossover pipe (buried below the frost line) can never go into siphon mode

Thanks, Rainman. I think I see what you mean. It sounds very reasonable. I can envision installing the vent pipe high enough above the top of the dam to keep it above any drifting snow. An inverted U at the top (or a breather cap that's open on the bottom) should help keep out falling snow and 'most' blowing snow. In either case, your suggestion about a critter guard is also well taken.

One thing about blowing snow is that it can find its way through any crevice or opening, especially if there happens to be a slight negative pressure on the other side of the opening. If the pipes are open to the air at two points (the vent and the outlet), I'm thinking that there might be some wind-related situations where blowing snow could be sucked into the vent pipe. I'm wondering if there is some kind of vent design that would take blowing snow into account. Maybe making the vent larger? Or, maybe it's not a major concern. Does anyone have any experience with venting pond spillway systems in a blizzard-prone area?

Somewhere I have a photo of a sizeable snowdrift inside one of the front doors of our house. It was a very windy snowstorm, and the wind blowing across the top of the house apparently created a slight negative pressure inside the house...just enough that snow hitting the windward side of the house got blown and sucked in through any small crevice. In this case there was a gap of maybe 1/16" under the front door. This was in a portion of the house that was being worked on, and the bottom door seal wasn't in place yet, but that small gap was enough to create a large drift of snow on the floor.

Would you also suggest installing a separate drain pipe and valve in case you wanted to drain the pond when the water level is below spillway height? Or would draining the pond be such an infrequent event that for those rare occasions one could just connect a pump and either pump or siphon it through the hose? I suppose it depends a lot on the size and condition of the pond and how often it will require maintenance. Hopefully, that will not be often.

Or, I guess that a drain pipe and valve could be incorporated into the plumbing you described, rather than being a separate unit. The valve, I realize, would have to be placed below the frost line.

Thanks again.

Blowing snow getting sucked into a 2" minimum sized vent pipe will never be an issue. even the tube buried in snow would still allow enough air to enter and avoid a full siphon mode starting.

You could create an A style pip, with a valve in the A cross pipe to control the full draining, but it is less expensive and probably easier to maintain if just capping the vent pipe and using a vacuum pump to start a siphon, if ever needed.

Rainman, judging from your various posts, you certainly have lots of good ideas and suggestions, and you could be right about the blowing snow and snowdrift issues. On the other hand, I'll have to say that snow can do some very weird things in a heavy blizzard with high (60+ MPH) winds. I've seen snow get packed quite solidly in and around things over the years, so I don't think I'll totally rule out the possibility of plugging just yet. I'll take your opinion into consideration and give it some more thought.

Another scenario has just popped into my little head: What if a moderately compacted snowdrift formed and then was rained on, either by ordinary rain or by supercooled water (freezing rain) in an ice storm, forming an ice-crust seal? Freezing rain is quite a common occurrence here in Maine, and it can form quite a solid crust over snow...sometimes strong enough to walk on without breaking through.

In any case, it's possible that the topography of the drainage, combined with the thick rows of trees and brush immediately around the proposed dam location, would not favor the formation of deep drifts, so maybe the issue is moot. I'll have to check it throughout the upcoming winter and see how the white stuff behaves in that area during different types of snow storms.

I'll also try to measure the winter stream flow at a few different points in the drainage. I haven't yet figured out a good way to measure the flow under the snow, but a couple of ideas are starting to form. In the meantime I'm open to suggestions.

As to installing a drain pipe, I agree with your opinion. Keeping the plumbing simple should reduce costs and avoid some potential maintenance issues, and if at some point I had to drain the pond, it would be easy enough to cap the vent and connect the suction side of a pump to start the siphon. I've got an 8HP trash pump that I think would do the job nicely.

Thanks again.

I've seen more than once in our area in the winter during a high water event ice form in trees or areas a person would never expect to see ice. Then the water lowers and the ice is left hanging.

It would be bad if a pond were at a level high enough for the water to freeze the vent shut.

Maybe an unlikely scenario, but not impossible. Where we are not around the pond most of the winter, I don't like to leave things to even the improbable. It is different if a person is around all the time to monitor it. I would hate to come back to an empty pond.

I'd be around a good deal of the time to keep an eye on things, and at the least, I'd check it after any major blizzard. It sounds like you probably head south for the winter, which is what a lot of Mainers do. Where are your winter quarters? I know several people who have winter abodes in Florida, Georgia, Arizona, New Mexico, etc. It's something that we might eventually consider, at least for January and February. I suspect, however, that we'll probably be spending winters here in Maine for some time to come.

The pond water level should not be able to get high enough to freeze the vent shut, since I'm thinking that for my pond design the vent would extend straight up above the top of the dam for a few feet and would have a breather cap and critter screen on it. The water would have to be several feet higher than the dam to close off the vent. The only time I'd cap the vent and employ a siphon effect would be for draining the pond. My question was whether or not a snow drift might get high enough and packed tightly enough around the vent to plug it and allow a siphon action to start if the water flow happened to be great enough to fill the down side of the pipe and pull a vacuum. Not too likely, perhaps, but I like to consider all possibilities. I'm not an engineer, per se, but I like to over-engineer things and have double backup systems, etc. I think I drive my wife crazy sometimes, but she puts up with it...so far.

Most siphon systems are designed with a 45° on the end to act as a "P" trap, not letting air back up the pipe. So, there would only be one end that was open, the vent. The vent is there and placed at a height that if water covers it, it self starts the siphon system. Once the vent is back uncovered, it breaks the siphon and the pond won't be drained dry.

In your instance, I'd maybe think of putting a large cap over the vent tube top - say suspending a 6" dia cap over the top of the vent to prevent snow from directly falling or blowing into the vent tube, but still allowing air to go up inside the cap, then turning 180° and going down the vent tube. Maybe drive 2 stakes into the ground on each side of the vent tube, and screw the cap to those stakes, leaving it suspended over the top of the tube. Say 1" or so air gap between the top of the vent tube and the inside top of the cap, sorta like a mushroom and stem, but the stem wouldn't be attached to the mushroom cap.

esshup, your suggestion about placing an open-bottom cap over the top of the vent with an air gap between the cap and vent pipe is an excellent idea, and the open bottom of the cap could have a critter screen in it, too. As you must have already surmised, a conventional vent wouldn't work, since the pond would have about a foot of ice on it in the winter, which would freeze a conventional vent closed, and I would need to keep the water flowing under the ice all winter.

Actually, the more I think about the proposed dam, the more I'm convinced that I don't want any siphon action to take place during normal operation. The reason is that the bottom of the drainage below the dam is very delicate, consisting of soil/silt held together by a thin mat of vegetation, and the little channels that the water runs through have a silt bottom. I'm concerned that the channels and the adjacent vegetation could be damaged by a sudden rush of water. So, I'd really like to keep the flow of water through the drainage below the dam at a slow, constant rate, as if the dam weren't even there.

Basically, I'd be looking at a very simple plumbing system...sort of an internal spillway that would not freeze in the winter, and with an air vent to prevent a siphon action from taking place.

The only time I might want to siphon water would be if I had to do some repair work and needed to empty the pond, and I just had an idea as to how I might be able to do that easily without producing a big rush of water down the drainage.

Here's my idea: I could place a valve on the end of the exit pipe (which would be several feet lower in elevation than the bottom of the pond), close the valve, fill the pipes to the level of the pond by pumping some water into the vent opening or just letting the flow of water from the pond do the filling, and then cap the vent and open the valve to start the siphon. There would still be a bit of air trapped in the pipes above the pond level, but it wouldn't be much, and I think the siphon would probably still start OK. In my case, I could adjust the valve to produce a normal flow of water to avoid a rush of water in the drainage. I would have to adjust the valve occasionally as the level in the pond dropped in order to keep the flow relatively constant, but that shouldn't be too hard to do. Another thought: I suppose that if one wanted to completely fill the pipes with water all the way to the top of the vent to get rid of any residual air, a vacuum pump could be connected to the vent to suck the air out. Correct me if I'm wrong (I've been wrong before), but I think that the vacuum pump approach would have the advantage of being able to fill the pipes all the way, or nearly so, even if the level of water in the pond is lower than usual but still above the intake. I'll make a drawing of my idea and give it some more thought. This idea is still a 'work in progress,' but who knows...it might work. I'm still a newbie at this pond stuff, so please chime in if I overlooked some key detail or figured something wrong.

Sounds like a plan. How much water will the pond see if you get a 100 year rain event? Just the rainwater or will it see some running into the pond from the watershed?

In a major rain event, there would be some additional inflow to the pond from the surrounding fields...just exactly how much I don't know. My plan is to monitor major precipitation events and make notes about the flow increases that I observe in the portion of the drainage that would contain the pond. I'm not sure how accurate I can be, but it should give me a better idea of how to design a system that could handle a substantial increase in flow.

I can see several possibilities, such as using large enough pipe in the system to accommodate a major flow increase, using a dual pipe system setup, having an erosion resistant emergency spillway over or through the dam, etc. I really haven't given this much thought yet, but that's one reason I think this forum will be a good resource for me.

By the way, I made some edits to my previous post about my idea for starting a siphon with the use of a valve on the exit. I'm still not sure if it's a good approach or not, but I'll draw up my idea when I have a chance and post it for a critique by the members. Maybe I'll make a scale model and try it.

Posted reply to wrong thread. Sorry. Deleted text.

Snrub

esshup brings up an excellent point on the 45 outlet...it WOULD freeze. A spring loaded, rubber flap valve on a 22.5 degree angle would allow enough water to drain, eliminating the "complete" freeze blockage danger, and preventing air entering. Even IF air entered, a siphon would restart.

BUT, this is a bottom draw system that can be converted to siphon...NOT intended to ever start a siphon unintentionally. I do not think a snow drift, or even a ice covered drift could ever become air tight and not allow enough air into a vent tube to cause siphoning to start. The key, will be burying the pipe in soils deep enough to ever allow freezing anywhere in the pipe where water is always present. Flowing water will always be warm enough in the pipe to keep anything more than peripheral icing over. Like a thickly ice covered river, water stays warm enough to flow.

I appreciate your feedback, Rainman. I tend to agree with you, insofar as I think it unlikely that the vent would become hermetically blocked in the winter, although I plan to give it more thought, just because it's my nature to consider a lot of different 'what-if' situations.

As to a 45-degree trap, it also appears to me that it could freeze solid if/when the water flow rate is too slow to keep it clear of ice, although in my current mode of thought I'm not considering using one of those anyway.

The artesian water well at our Alna house has a stainless steel overflow pipe that extends out into the air, thus being exposed to sub-zero temperatures, and it has never frozen. I suppose that there's enough water flow through it relative to its area, mass, heat conductivity, etc., to keep it warm enough to prevent any ice from forming.

As to the water flowing through the pond under an insulating layer of ice, I don't anticipate a problem, at least not at this point, but being new to this, I plan to do some reading to learn more about ice formation and the factors that influence it to see if I might need to make any alterations, such as pond basin shape, depth, width, water entry, etc., with the goal of dependable flow in the winter and good ice formation.

We live on a tidal, freshwater portion of the Androscoggin River in Brunswick, and a lot of water flows under the ice, so I'm somewhat familiar with that situation. The ice, combined with tidal changes, currents, expansion, spring breakup, etc., is a formidable force. I just finished building a floating dock at the Brunswick house, which has to be removed from the river each year before winter or the ice would destroy it. We have roughly a five- to six-foot tidal range here that moves the ice around, and when the ice breaks up in the spring, the floes floating down the river can do a lot of damage. But that's getting off on a tangent.

Anyway, as you said, any part of the pipes in the dam that would retain water would have to be placed well beneath the frost line. I would also guess that it might be a good idea to place them a little deeper than usual, since I imagine that because of the shape of the dam, the earth in the dam has more surface area exposed to the cold air relative to its mass than the equivalent amount of earth below a flat surface...or at least that's the way it seems to me.

What I envision so far is some kind of simple, low-maintenance bottom-draw system as you mentioned, preferably with no moving parts to depend on for its normal operation, which would allow the flow rate in the drainage below the dam to remain basically normal and consistent. And if I can convert it to a siphon situation if/when I want to drain the pond, that would be great.

I eventually plan to draw up some design ideas and post them to get some opinions on how well they might work...or not. And of course I'd like to get your feedback on them.

This week, I hope to take some core samples of the soil in the bottom and the banks of the existing drainage area where I envision the pond. I’ll call our local county extension office and see if they can perform any pond-related analysis on the soil. I also plan to do some bucket testing.

Besides what I suspect is clay under a layer of topsoil in the pond site, I’m also planning to investigate another source of clay on our own land. Near the back of our property is a now-overgrown area where clay had once been dug for making bricks...probably back in the late 1700s or early 1800s. I'll have to sample some and see how it would work for water retention, but I’m optimistic about it, since the surficial geology map of the area shows the clay as part of the Presumpscot Formation. According to various sources, the Presumpscot clay was not only used for brick making and pottery, but also is used as an impermeable fill to cap landfills or other hazardous-waste sites.

As mentioned, the pond would have to be located far enough downstream from the spring area and our home's domestic artesian well that it would not affect the domestic well system. However, I'm not sure what will happen to the water flowing down the drainage from the spring in the winter when it reaches the ice that forms on the pond. Somehow, I want to make sure that the water will flow under the ice and not over the top of the ice. I'm wondering if this might take care of itself naturally, or if it will require modifications to the stream bed, or some kind of catchment/plumbing system, etc. I'm open to suggestions, but I suspect that I will probably have to conduct some observations and experiments over the winter to get a better idea of what the variables are.

I agree and think you'll have to know just how far your springs flow before (or if) the output freezes completely by observing it this winter. Like any stream, there will always be some flow on top of an ice blockage, but once that builds up, it becomes insulative and the water flows close to the warmer earth.

Thanks. I'll definitely plan on monitoring the water flow over the winter.