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| valign="top" rowspan="715" | <font size="5" color="#adadad"> <center><br><br>Using <br><br>local <br><br>materials <br><br>for pond <br><br>lining </center></font>
| style="border: 3px solid #efefef;" valign="top" | '''I was wondering if any of you have experience with lining surface runoff harvesting ponds, using local available materials as clay, bentonite or gley or cement/clay mixtures or that sort of stuff? Plastic liners are all good of course, but perhaps some local materials will also do the job if you allow some small seepage?'''
Sri Lanka
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|style="border: 3px solid #efefef;" |Hi folks,<br>
Hope you are still interested in this theme of sealing ponds. Clay alone will create problems if the pond level changes regularly with the clay being exposed to sun too long. In Peru, since ancient times clay was mixed with cactus juice. they would let it sit for a couple of weeks to 'cure' just like cement, and then apply it to line the canals. They lasted only 500+ years! Would do wonders for pond lining. Of course you have to experiment with the type of clay and cactus you have to figure out right proportions.
- K
Ecuador
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|style="border: 3px solid #efefef;" |Glad to hear that many are quite interested on the theme of pond lining. I gave a brief treatment on the issue in my book but unfortunately it is not in English yet. Will try to make amends below. The main issue in pond lining is economics; we don't find any material that are 100% impermeable, cheap, cheaper to repair and lasting over 20 yrs. So, let's analyze the issue in each case to see how much water you could afford to let seep-out.
In the case of irrigation water, if you are not using extremely expensive drip irrigation, your water losses during distribution will amount to over 30%. And since most irrigation water comes with a high concentration of fine silt/sand/clay, over time, seepage from your unlined pond will be less than even 10%. So, instead of trying cut down seepage with costly lining, you'd better spend your resources on improving the efficiency of distribution. On the other hand, if you can afford good drip irrigation, you may not worry too much about the kind of low cost treatments we talk about, but keep reading.
In the case of potable water, very few would keep treated water in an open pond, since you can´t afford to lose that quality. If you keep untreated drinkable water in an open pond, better figure out the losses you can cut down within the treatment process and compare that to the cost of lining your pond.
Now that you know how much you can afford to spend on your pond lining, it is easier to make a decision on the materials to choose from.
Clay pond liners came into being as social pressure built up to prevent leakage from waste dumps. It is cheap if the pond is quite large and the liner thickness is over 20cm, so that mechanical compaction is viable. It is not really clay, but clayey silt or silty clay (in engineering terms). For water ponds, such a material, well compacted, would hold the seepage to less than 10%, even if water level goes up and down, exposing it to drying. For smaller ponds, animal compaction (with buffaloes, like in Sri Lanka) may work, but you need more clay, with the risk of fissures developing upon drying.
For small ponds, a better choice will be a 'soil cement' liner, but not the version USBR promoted. I myself experimented in Ecuador with fine silty soil (ancient volcanic ash), well dried and sieved, and mixed with about 5% cement. We applied a 7cm thick liner, manually compacted, to an irrigation canal with a medium fast flow, and it held well for over a year (till the municipality donated 1000 bags of cement to the canal owners!). As a pond liner it may allow 2-3% seepage (not measured, but I estimate that based on the density). The beauty of it is that anybody can repair whatever fissure appears, bloody cheap and in no time. Now, Andean volcanic soil has a variety of minerals that may work well with cement to hold the particles together. You should experiment with the soil you have and you may try a bit of lime too. Cheaper pozzolanic cement may come in handy too.
On the use of cactus sap with clayey soil, I haven't had the opportunity to try it myself, but many friends of mine have and I got their testimonies. They generally use it as mortar between blocks of rock in canal lining and I am sure it was used in many ancient water reservoirs too, especially to cement the dikes. Following my prior reasoning, I doubt they went to the extent of lining the pond floor, as preventing that seepage was not worth the trouble. As far as the proportions and the types of clay used, I will consult with my friends, but you have to bear with me for a couple of months when I will return from my next trip to Peru. Internet is as alien to them as geomembranes!
Hope this helps. I value your comments. If you give details of the materials you have in the area, together we can come up with a decent solution.
- K
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|style="border: 3px solid #efefef;" |Hi Everybody,
With reference to the interest shown in reducing seepage in ponds and earth dams, kindly note that I have received good results applying the methods described as follows:
''Seepage in earth dams can be much reduced by compacting the floor using either a farm tractor or a herd of livestock driven back and forth over the floor. A thin layer of waterproof material, such as Black Cotton Soil, animal dung or lime, will also seal a dam reservoir.''
Source: ‘Household Dams for Maasai Women’ 2014. An unpublished manual by Erik Nissen-Petersen, ASAL Consultants Ltd., Kenya.
- E
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|style="border: 3px solid #efefef;" |Guess since we are not all civil engineers, a clarification is necessary with respect to pond lining.
My previous explanation applies especially to lining the bottom and the sides of a hole excavated in firm land. I would extend such arguments to a pond built up by constructing a dike across the lower edge of a natural depression, only if the depth of retained water is less than a couple of meters. Seepage through a dam / dike is a totally different beast compared to seepage through the floor of a reservoir / pond. My rationale behind comparing the cost of preventing seepage through pond lining and the cost of reducing water distribution losses does not apply in the case of seepage through a dam, because such seepage will compromise the safety of the reservoir itself and the people living below it.
Again, you can't prevent seepage through a dam 100%, but you should attempt to control it to a level where you can collect the seeping water without damaging the dam structure and then drain it safely using a system that works 24 hours a day. The 2000 yr old reservoirs in Sri Lanka had a very elaborate water control system (see link to the right) to prevent high pressure water seeping through the sluice gates, which is still intact today. They of course had elephants to compact those earth dams.
If you do not have access to such resources, the best bet is to have a series of small reservoirs (less than a couple of meters of water depth) in cascade, along the same river (see the same article).
- K
|style="border: 3px solid #efefef;" |[http://kyapa.netau.net/crianza/waternurt.htm ANCESTRAL WATER NURTURING TECHNOLOGIES]
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