Please comment on design. Cold temperate climate.

Discussion in 'Members' Systems' started by princesse_nomade, Nov 21, 2013.

  1. princesse_nomade

    princesse_nomade Junior Member

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    Hi all! thanks for taking time in your busy schedule to lookup my thread!

    I've created this design for a proprety situated in the Saguenay region, in Quebec. My main worry relates to the construction of a dam to try and reduce seasonal floods. It is my first design, and I wouldn't want to make any crucial mistakes.

    It is a challenging site, for the following reasons:

    -Complicated site-scale topography. Composed of large mounds/car-size-clumps of almost pure grey clay (upon which trees, bushes and herbs have grown) randomly positioned within an almost pure sand. Topsoil is generally shallow, sometimes inexistent.
    -Situated half-way between a marshy plateau and a valley that empties into the Saguenay river, there are lots of run-off waters.
    -Over exploitation of trees by upper (west) neighbours, insufficient topsoil to absorb run-off waters, and compaction by animals (horses, and humans) results in regular floods, especially in spring and fall.
    -Local people also say there are underground veins of water that contribute to the accumulation and running of water in some areas. It does seem to be the case.
    -Streams are very shallow (one or two feet deep) and run on clear sand.
    -Surrounding forests are quite marshy, but there are zones where trees have favoured soil stabilization and accumulation.

    On the other hand, there are quite a few great aspects to the site too :

    -Water! There is a great opportunity here to build a very fertile piece of land by installing different types of water harvesting features.
    -Clay. Good, almost pure clay that can be harvested wisely to build excellent ponds, and other catchment features.
    -Forest. A fair variety of plants and trees that encourage soil building and stability, provide food and medicine, as well as shelters for diverse wild animals (deer, hare, birds, mice, squirrels, and others), which in turn may be integrated to the subsistence strategy. Very importantly, the tree belt surrounding Fanny and Jean’s land creates a microclimate. According to them, and from what I’ve experienced, temperatures seem to be more stable year-round, and while it remains strangely cool(er) during the summer, it is about 8°C warmer there during the winter.

    If you look at the design, you will see ponds named : duck pond and wildlife ponds. Knowing that waterflows into the site from the West (blue arrows on image 1), I'd hope that a dam (with keypoint and all) would prevent run-off water from flooding the site each sprinf and autumn. Do any of you see any problem with this theory? Or other problems, of course!!
     

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  2. Rick Larson

    Rick Larson Junior Member

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    How about silt traps along the stream? You can also arrange the rocks in the stream to create scour holes. Your design looks good to me!
     
  3. 9anda1f

    9anda1f Administrator Staff Member

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    Excellent! Your drawing looks to be quite detailed ... however the electronic image suffers somewhat in translation, so I have a question. Could you explain the general water flow features (that are most likely clearly annotated on your original drawing but I cannot make them out on the electronic image)? It appears that the "high point" is at the top/center of your drawing (west) and makes it's way down the series of wildlife ponds, down a wetland along the driveway, under the drive near the bottom, then into the existing trout pond complex?

    Is there actually a dam in your design?

    Thanks. Your work looks great but I wanted to make sure I understand your water patterns.
    Here's my slightly "enhanced" version of your plan:
    View attachment 1914
     

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  4. Rick Larson

    Rick Larson Junior Member

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    The darkening is better, but I still can't read the words very well. Another question; will the house be exposed to underground water from what appears to be swales upslope?
     
  5. princesse_nomade

    princesse_nomade Junior Member

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    First, thank you for answerinf and also for the enhancement: I realized yesterday evening that the drawing had indeed suffered in translation. Here are macros of the area we're discussing.

    Maybe I used the wrong word: dam / pond. I think you got the site's water flow right. Here are some more precisions, I hope this helps.

    Duck pond
    Currently, the area that will become «Duck pond» is a clay deposit. We will need the clay to build Wildlife ponds a, b and c, so why not build another pond?
    Duck thus receives water from upper ponds and streams, flows into Wildlife ponds through baffles or steps (Duck pond is slightly higher than other ponds).

    Wildife ponds a, b, and c
    These ponds would be the key to pacify water on the site. Most water comes from springs and ponds situated west (upland) of the property, and ends up criss-crossing across the forest right at the location of «Wildlife ponds». These are actually already seasonal ponds. Catching this incoming water into permanent ponds would certainly help with the seasonal flood issues.
    If need be, excess water would come out through the spillway, right into an already existing canal (planted with reeds) just south of the entrance road. This ditch thus leads to a large pipe, and water exits after having been filtered by a reed bed, into "Deeper fish pond-trout".
    At this state, I’m not sure what kind of fish to put into «Wildlife ponds», so I thought maybe just Phoxinus phoxinus, and we’ll see later on.


    I think it makes sense. However, because the soil is mostly sand (with bolder-size patches of clay as mentionned above), I'm worried that the ponds, even if they collect surface run-off and excess waters from up-land, will not change much and that underground waters will still be a problem. View attachment 1916 View attachment 1915
     

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  6. princesse_nomade

    princesse_nomade Junior Member

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    Yep, this was another concern. The area designed as covered with swales is already soaked in autumn and in spring. I was hoping that the swales would help recuperate this water, and push it farther underground, enough so that it would make its way into the "marshy" forest. I thought that the reed-bed gully situated north of the swales, and the road would act as a buffer. Also, the house would have to be build on a mound.

    When I look at people's design, I do not always see how people manage the effect of swales (where water slowly gathers downhill and creates the opportunity for a pond). I'm currently looking into it.

    Anyways, I hope I understood your questions right, me being french and all...

    Also, thank you thank you thank you!
     
  7. 9anda1f

    9anda1f Administrator Staff Member

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    Notice the water plume and the impervious layer in this clip from Geoff Lawton's "Harvesting Water" video. It may provide some insight into your property.

    [video=youtube;UFeylOa_S4c]https://www.youtube.com/watch?v=UFeylOa_S4c[/video]

    I can imagine from your description that an impervious layer of clay may lie beneath the sand (although it's merely a guess). Only a dig would tell for sure.
     
  8. Rick Larson

    Rick Larson Junior Member

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    The mound should work as long as the lowest footings under the house are above the lowest point of the swales. In Goeff's PDC he talked about the house at Tagari Farm as having a trenched then rammed earthen mound bending around the swale side of the house.
     
  9. princesse_nomade

    princesse_nomade Junior Member

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    Oh wow! I never saw that video, although I have the complete earthworks course. Well, you know what, I think the entire site is situated at that spot where water starts to rise and reaches the surface: it is kind of in a kettle geomorphologically speaking. THANKS (again!!!)
     
  10. princesse_nomade

    princesse_nomade Junior Member

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    Yes, I remember that part, which is why I was not too worried about the house, but more about flooding the area below the swales. But now, I think I can manage, thanks to your advice and video! I'll let you know what my "clients" decide to go with and I'll post pictures of the works. Next summer: because now, it is starting to snow here!
     
  11. eco4560

    eco4560 New Member

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    Pond v dam - in common usage in Australia ponds are little bodies of water that are not permanent - something knee deep and 2 meters across would be described as a pond. Large permanent bodies of water would be called dams.

    Hence the confusion…..
     

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