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Page 2 of 3 the 200 gallons of water being treated causes the pH to jump up to the high Ts to the low to mid 8's. At the moment we are not sure what to do about this. We are in the process of ordering a more dilute caustic soda solution as you had suggested. Currently as you noticed we are using a 50% solution and we are seeing if we can get a 10-25% solution to try out and see if that helps. In addition we have also been researching as much as we can about the correct operation of septic systems. In this research I have came across what seems to be the best and most comprehensive document (out of dozens I have looked at) on septic systems and their operation, it is from the State of Washington. I have attached the document to this e-mail for your review and highlighted sections of the document where it discusses pH ranges on pages 5, 8 and 11. In this document it discusses the "ideal range" for bacteria growth which you mention in your e-mail below. However, it also mentions a normal wastewater pH range for septic systems and that is from 6-9 pH. Apparently this is also the ANSI/NSF Standard for wastewater going into septic systems. Here is an excerpt from page 11 the "conclusions" section of the document: "To protect microorganisms during anaerobic digestion, the pH of the wastewater needs to remain between 6 and 9. ANSI NSF Standard 40 for residential wastewater treatment systems requires the pH of individual effluent samples to be within this range. This is a reasonable pH range to use as single -sample values for residential septic tank effluent where the pH should remain at or between these values." Based on this information we would respectfully like you to reconsider the proposed pH range limit you are discussing in your e-mail below. If we could have a range of say 6.5 to 8.8 or the full range of the standard, it would make it a lot easier for us to comply. As I stated before it only takes one drop of caustic solution in 200 gallons of water to put us over your proposed limit. Let us know your thoughts on this matter and if you are open to using the ANSI/NSF Standard. Best regards, Ed Morris Edward Morris VP Engineering Process Specialties, Inc. Phone: 800.533.8820 / 209.832.1344 www.processpecialties.com Timothy O'Brien wrote: Ed, My reference material indicates typical septic tank effluent should be in the pH range of 6.5 to 7.2. I'm willing to expand that to 6.5 to 7.5 as the target range. I'll be preparing a letter describing my visit and specifying what tests we would like you to run before determining the lead agency. You had mentioned that you would begin experimenting to better control the pH. Please keep me posted on the progress and let me know if you have any questions. Timothy R. O'Brien Engineering Geologist Central Valley Regional Water Quality Control Board 6/15/2011