Friday, July 29, 2011

Sub surface Tank construction: A mini project in itself..

Things are starting to heat up at Savera Farms while the temperatures have finally started to decline. We are 3 days away from planting Melia Dubia and all of us have been busy with drip installation, manuring, and getting ready for planting our first batch of saplings. Due to a busy schedule especially on the infrastructure front like shadenet, water tank, drip etc, I have not been very regular on the blogging..
This post is on construction of Sub surface tank which essentially will be used for water storage. Three borewells will feed in the water and there will be one outlet that will irrigate approx. 30 acres via drip pipes. Due to a big acreage and moderately high water requirement, a tank was deemed essential. In addition, storage is essential especially in areas with regular power cuts.
My photo timestamps show that it took us 7 weeks to complete this. The dimensions are 40 ft x 40 ft x 5 ft and has a storage capacity of approx 2 lakh liters.
Below are some of the pictures of the tank construction and hopefully will give you a good idea on this engineering marvel!


JCB was able to dig the pit in approx 8 hours..
Constructing a solid foundation is imperative due to pressure exerted by underground water level during monsoons. We used a mix of cement, stones and sand.
Walls are erected..
Working on the partition walls..
Reinforcing the side walls with 'chicken mesh'. Cement was plastered over the mesh to give the structure more strength.
Plastering in process..















One of the three borewells is finally functioning.



Engineering marvel is finally up and functional!!
















Next week, we will be attaching SST submersible pump to the drip setup. More details on drip in the coming weeks!



24 comments:

  1. Looks Good!!

    -Rajesh

    ReplyDelete
  2. I am regular follower of your blog and I like it very much, Currently I am into Software but want be a Live Stock Farmer in future. I have simple curiosity here that why the partition walls are built in the tank, is it to divide the load of water or to do any water filtration or any other reason and why the rectangular shapes are given in partition walls, can you please explain a bit more.

    Thanks & Best Regards
    Abdul Moyeed

    ReplyDelete
  3. Abdul,
    You have better control over the water when walls are present. In pic 6, you will notice a cylindrical opening on the left side of the partition wall. You can control the flow of water by opening/closing it..Moreover, cleaning becomes easier - you can close one section, clean it up and then let the water in..

    ReplyDelete
  4. How long does your 3 bore runs to fill up those tanks? What is the power consumed to fill these tanks?

    ReplyDelete
  5. Currently, we have 1 bore operational. We hope to have 2 more EB Connection shortly. Assuming avg discharge of 250LPM from each bore and tank capacity of 200,000 L, it should take 4.4Hrs.
    I am using 5 hp motor for bores and 7.5 hp motor for tank.

    ReplyDelete
  6. Hi,

    Thanks for sharing your experience.

    After you get the water into this tank, how will you use it via drip pipes. Do you need a motor to take the water from the tank to farthest drip in your system.

    -Raja

    ReplyDelete
  7. Yes, there will be a motor that will pump the water into the filtration system and then routed to the various parts of the field via drip network (pvc pipes)
    I will post the SST motor pics and drip setup soon..

    ReplyDelete
  8. Thanks again.

    We have bought a plain land in Kayathar (near Tirunelveli) to set up a organic farm. We are planning for the irrigation system. My thinking is it should use minimum electricity and at the same time reliable. Ours is a 20 acre land and i am thinking of constructing multiple overhead tanks each with 5000litre capacity. So electricity will be used only to pump the water to the tank and then by gravity i can irrigate using drip pipes. I am not sure if this is feasible. I am thinking i can use stones(used for foundations) to build a platform with 4ft x 4ft dimension to a height of 6 ft. Then can build the tank above it. From your experience do you see any problems in that approach?

    Thanks
    Raja

    ReplyDelete
  9. Overhead tank makes sense if you have 1 water source (borewell or well). You just have to pump the water once. Disadvantage is that it may be challenging to irrigate 20 acres with a overhead tank. However, you have mentioned that you plan on constructing multiple tanks. Check out what is the cost of construction.
    Moreover, what is your water requirement? 5000L is not a very significant amount of water..
    Platforms of 6 ft height will not take you very far as pressure will drop after some distance.

    ReplyDelete
  10. what is the cost of construction for a 2 lakh liter sub surface tank like yours? if it is completely on surface, will the cost come down?

    regards,
    Brijesh

    ReplyDelete
  11. this is a RCC construction? do you see any disadvantage of using ferrocement, as i believe this would bring down the cost considerably

    ReplyDelete
  12. Brijesh - Yes this is concrete mix construction. What do you mean by ferrocement?

    ReplyDelete
  13. See some links below, Ferrorcement is presumbaly (from information gleaned) the cheapest and most value for money for building water storage tanks with the highest tensile strength ratio. See chapter 6 of the below link

    http://www.schools.indiawaterportal.org/principals/rwh

    http://ieham.org/html/docs/Ferrocement.pdf

    ReplyDelete
  14. Do we need 7.5hp motor in tank to the drip? Why do we need such high power motor to draw water from a shallow tank?

    ReplyDelete
  15. I would not call it a shallow tank :) It is approx 2 lakh litres.
    To answer your question, basically it depends on your crop acreage, water requirement and operating time.
    You can install a lower hp pump (but keeping water requirement of crop constant), your operating time will increase (which increases your irrigation cost).
    Moreover, we (at least TN) has power up cuts upto 5-7 hours during the day, so it is prudent to irrigate as much area as possible when power is available (for this you require a higher discharge pump)

    ReplyDelete
  16. Hi,
    can you please share approximate cost of construction for this water tank .

    Thanks,
    Prashant

    ReplyDelete
    Replies
    1. Prashant,
      The cost can vary from Rs 1 - 2 per L, based on design, material, labour etc..

      Delete
  17. Dear Techie,

    As per your information, the tank costs 3 laks, +/- 1 lak. For the 1600 sq ft space, it works out to about 250 rs/sqft. Can you please tell us how days water supply is it supposed to hold. You said before that it is to irrigate about 30 acres. So much days of irrigattion will this tank of 2 lak litres give for the 30 acres?

    I am asking because in some places, I have seen one acre tanks, of 5 metres depth, being used to store water for almost 7-10 months needs of 9-10,000 trees. Also, the cost of these tanks is much less than your cost.

    ReplyDelete
    Replies
    1. Firstly, tanks are calculated by volume and not area. My tank is a cemented tank, so there is no constaint on how many number of days of water it can hold. You can replenish the depleted levels any time until the power is present.
      The tanks you are talking about are earthen tanks, without any concrete or cement. It will only work in areas where water level is quite high. Digging 1 acre tank x 5m deep is going to cost you a lot via JCB. What estimate do you have?

      Delete
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