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Todd Stong email on scope of his team work in Microfarms

(1) WATER PURIFICATION for the family on site based on (a) a shallow or deep well, or (b) a stream or lake. I will provide a detailed diagram for a slow sand filter system for a family of up to 8, plus a step by step account of how to make that family sized system. Disinfection will be accomplished by the biological layer that forms on the surface of the filter's sand after a few weeks. Chlorine (household bleach, 5.25% chlorine) will be offered as an alternate/supplemental method of obtaining disinfection

(2) DOMESTIC SEWAGE DISPOSAL for a family of up to 8. I think I would go with a composting toilet. But a septic tank could also be proposed as an alternate, an aqua privy, given that you most likely will not want to have flushed sewage so as to conserve water. The aqua privy would be directly beneath the toilet so there need be no water flushing. Anaerobic digestion would take place with odors carried off by a vent pipe. Exiting water could go into a drain field if you are not open to using it in the fish pond.

As to the composting toilet you appear quite familiar with the developments of the past 20 years and recognize that its success depends on the users doing exactly what is called for in regards to mixing human waste with vegetable waste to maintain the decomposition in the aerobic mode. I would further suggest separation of the urine so it may be used directly for the agriculture. For sites that are naturally quite dry you could let the urine go into the composting toilet if you wished.

(3) WATER SUPPLY for the mini-farm. This may include engineering design for pipe lines, pump sizes, use of a surface source or a ground water source. If you have a collection of your one hectare plots it may be economically feasible to create a central water supply with a pipeline. If you have an isolated one hectare plot it may be too challenging to reach for 50 CM of water a day if that water can not be gained from a lake or stream within 100 meters. I think you may want to offer options of how to develop your mini-farms based on the economics of water supply. As you said and as your Web site defines, over 80% of the income of your mini-farm comes from the hydroponic grown lettuce which is gown on it seems less than 20% of the site. When facing expensive water I would suggest you opt to depend mostly on the hydroponics and fish farming. If water is readily available at low cost it becomes easier to support the corn and legumes.

(4) SANITY CHECK ON COST ESTIMATES FOR CONSTRUCTION may be an area where I can help. Any engineer has the capacity to provide a 10 min, a 30, min an hour and a 10 hour estimate for any construction. Often in working the options for a project one needs the 10, 30 and 60 min estimates to gain perspective and to offer a first order check on the work of others who may have missed something. Regrettably you can encounter the engineer who won't put his neck out for a rough estimate and ops for a mini-dissertation. In truth real word estimates relating to construction are iterative, redone several times as better data is obtained and as the project designer adjusts after they see the cost impact. If local unit prices are sought estimates can be good for what they consider in the job, but they sometimes will miss something needed. I would suggest for example that as you move to design something that you put it up on your site asking others to offer you cost estimates along with their assumptions on unit material prices and unit labor production rates. That way you will quickly zero in on what is reasonable.

Todd Stong



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