As a former septic inspector, I don't know of specific design criteria for
absorption area to garden area separation. Try contacting your local health
dept. and or a qualified design engineer. I am sure there must be study data
covering this subject as I remember mention of "phosphate creep" and
biological and chemical loading being factors in establishing separation
distances. IMHO, I would certainly not be comfortable with anything less
than 25 feet, and preferably 50 feet plus, separation assuming that your
system is functioning properly and with no lateral transport of effluent via
bedrock, glacial gravel soils, etc.. Consider that NYS DOH Appendix 75-A
Wastewater Treatment Standards requires 100 feet separation between the
absorption area and a body of water, pond, stream or well. Cornell
Cooperative Extension http://www.research.cornell.edu/VPR/vpr.html has a
wealth of information on many subjects including sewage disposal systems. Be
safe and good luck.
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