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Micro Farms Project Email Record

Todds summary of water issues with Raanan


DRIP IRRIGATION I agree that it may be best to phase in the drip irrigation once we better understand the character of the water coming from the fish pond.

WET-LAND The idea of a wetland area needs to be evaluated based on how much land out of the one hectare can be taken out of other crop production. Such facilities are designed to consume nutrients while it seems we wish nutrients to go onto the crops. Yes, some crops could be raised in the wetland, as suggested to feed the goats, chickens, ducks ..... Solar losses in the wet land need to also be accounted. Surely their is a balance that can be found here. Again this seems an idea for a later phase.

POND GEOMETRY Natural oxidation levels in the fish pond, scarcity of electric power, solar heating and evaporation of pond water, child safety, and the land area required by the fish pond are some of the considerations for setting its geometry. Let me suggest as an opener a depth of 80 cm, a freeboard of 50 cm and bank slopes of 2 to 1 (given a rock covering). For the 10 day, 490 CM water capacity, that suggests a land area of about 650 SM, 6.5% of the site. That relates to a single square pond of 25 meters on a side, a rectangular (4:1) pond of 13 M by 50 M. For water flow, possible fish segregation, and alternate water drain off, I would favor a rectangular configuration, the longer the better. But, then again, the slope of the site will dictate just how long such a pond or system of ponds can be and yet have the water move on by gravity to all the crops.

SITE SLOPE Suggest we assume a site with a 2% slope at this point and press on with a design of the pond geometry. If we have more slope we could stretch the pond, and if less we confine it more to the highest ground.

FISH EXPERTS Need now the input of the fish experts to bring this pond design closer to a close.

RAW WATER Need some assumptions here to move on with optimal selection of both crops and fish.

DOMESTIC WATER PURIFICATION AND WASTE TREATMENT I will provide a slow sand filter design for the water treatment. Assume for now an area of 1x2 meters, with a 3000-6000 liter water storage cistern below ground and possibly an elevated tank (100-500 liters) on the roof of the house if the family is inclined to pump water up to it. I would also recommend chlorination (3 gallons of Chlorox a year) as a backup for the family's possible mis-operation of the sand filter. For wastewater I would prefer a composting toilet, but will be ready to offer a septic tank system needing an area of 2x3 meters below ground for the tank and a drain field of 5-20 SM depending on the permeability of the soil.

CROP MARKETING This remains an area of keen interest to me. The sale of what this hectare produces is critical to the success of this family. Otherwise this project is more simply just another experimental farm. What they raise needs to be of interest to the market. Arrangements need to be made to assure a market at some reasonable distance. Hopefully there is another group like ourselves exchanging e-mails on this topic. It may be too much to expect the family to secure markets plus cultivate the crops and raise the fish.


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Revised: 4 April 2003
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