Anyone use a pea gravel sand mix?

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by stone_family3, Jan 24, 2012.

  1. stone_family3

    stone_family3 Chillin' With My Peeps

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    Apr 11, 2011
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    This winter has been rainy and the run is a huge mess. I was thinking of doing a mix of pea gravel and sand, but wanted to see what other's experiences were.
     
  2. Buiscuit

    Buiscuit Out Of The Brooder

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    Alabama, And I hate it !
    I let mine free range. But recently they have been roaming deeper into the woods. So I am thinking about closing mine in and am interested in what people suggest also.
     
  3. stone_family3

    stone_family3 Chillin' With My Peeps

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    i live in the city and I'm not exactly permitted, so I have to keep mine in a run
     
  4. chezpoulet

    chezpoulet Out Of The Brooder

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    I would use just sand. I made the mistake of laying down gravel under the sand, and the chickens kept digging up the gravel, and it became really hard to sift out the poop with the kitty litter scoop. Once I slowly got rid of the gravel, cleaning became a lot easier.
     
  5. teach1rusl

    teach1rusl Love My Chickens

    Mine (in my bantam coop) is mostly coarse sand, but it does have small pea gravel mixed in...that's how it was sold. I love it.
     
  6. It is actually very ideal. It would be close to a course river sand. Try calling around about that.... it is a very course sand with tiny pebbles in it. It does not compact down as bad as something like play sand which is screened to be all the same size. Since it does not pack as hard, it drains much better. The courser sand and very small bits of gravel is better grit for the chickens as well.
     
  7. Pico de Gallo

    Pico de Gallo Out Of The Brooder

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    ABQ, NM
    Nope, I'd not do it. The more homogenous a sediment's grain size distribution, the greater its porosity, thus faster infiltration rates. Blending peagravel into sand is the exact opposite. Coarse, well-rounded sand of uniform grain size will absorb precip faster than anything else...

    Beach sand.
     
  8. stone_family3

    stone_family3 Chillin' With My Peeps

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    This is the type of sand I was thinking about. since I have mud/dirt already I was thinking of mixing some in with the dirt, then topping it off with an inch or two of river sand and pea gravel.
     
  9. I think you will be fine with that. Regardless of the above post about size uniformity is good (its not) there are probably over a 1000 post just on BYC alone about using a course sand of non uniform size. Many of these post come from folks that have been doing this a whole lot longer than me. I'd go with the experienced crowd....
     
  10. Pico de Gallo

    Pico de Gallo Out Of The Brooder

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    Jan 18, 2012
    ABQ, NM
    Look...we're really just splitting hairs at this point. As neither of us actually lives there in OH, it's impossible to say with absolute certainty which material is best. And viewed from a hydrogeologic perspective, S&G and well sorted sand are very similar in hydraulic conductivity (how quickly water migrates through a material) and storativity (how much water can be stored within a material's void spaces). Allow me to explain the differences.

    A thick (10"+) wetted bed of highly permeable material is essentially a miniature perched aquifer, and for our purposes I'l treat it as such.

    I need to amend what I stated in post #7 since I'm about to go into gory scientific detail: S&G will probably yield slightly higher infiltration rates than pure well-sorted sand, though with reduced storativity due to its having a lower porosity (proportion of void spaces to solid particles). Gravel provides large surface areas across which percolating groundwater can move faster than it would through sand, where water is obliged to follow tortuous paths between tiny particles. On the other hand each gravel particle has practically zero capacity for storing water (as it's a solid chunk of rock), and an identical volume of sand typically contains btwn 30 and 50% void space (which can be filled with water) between sandgrains.

    Here's how similar they are, storage-wise:
    10 yd3 of sand (with .4 porosity) can potentially store ~4 yd3 of water.
    10 yd3 mixture of 80% sand (.4 porosity) + 20% gravel (.1 effective porosity, if that much) could store ~3.4 yd3 of water. Perhaps even less.

    The real question is, which is more important to your particular environment? Maximizing temporary storage, or maximizing infiltration rate?

    This greatly depends on local soil: if it's clayey I'd go w pure sand to maximize temporary storage, as it'll take far longer for excess runoff to infiltrate into the ground. If the local soil's got decent drainage properties, I'd go w S&G, as you can move that water from the surface and into the ground at a faster rate.

    How deep is the water table? Near-surface I'd go pure sand, as that water will be standing regardless of infiltration rate.

    Side by side in a major rainstorm: The pure sand bed will form initial puddles before the S&G bed does. Once the S&G bed becomes saturated, it too will form puddles. After the rains abate, the sandbed's puddles will quickly disappear as the excess water drains into the unsaturated portions of the bed, whereas the S&G bed might maintain the puddles until its already stored water can infiltrate into the ground. In really big rain events they're likely to behave the same, quickly becoming saturated and slowly releasing the water as dictated by the underlying soil's hydraulic properties.

    Pea gravel can make nice supplemental grit, so that's yet another consideration for fowl-minded folk.

    Whichever you go with, try to use rounded over angular particles: greater porosity, and they don't compact as well (which further reduces porosity). As for uniform (well sorted) vs non uniform (poorly sorted) grain size distributions: you truly want well sorted to maximize storage. Adding large particles might help infiltration (though with a small cost in storativity). Adding smaller particles (clay, silt, fine sand) is really bad: this will fill voidspaces, decreasing porosity and storativity, and retard your infiltration rate.

    If you really want the best in both worlds: first lay a coarse gravelbed of rounded river cobbles (think drywell), cover it with landscaping cloth (prevents sand from filling gravel's voidspaces while allowing water to pass), and blanket this with ~10" cover of washed masonry sand.

    And at the end of the day...I'd prolly just buy whichever's cheapest!

    Hope this helps more than it confuses!
     
    Last edited: Jan 27, 2012
    1 person likes this.

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