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ACCEPTING SEPTAGE at your WWTP

ACCEPTING SEPTAGE at your WWTP. Kay Curtin MPCA- St. Paul. Why are treatment plants taking more septage?. Mandatory pumping – every 3 years Don’t want to lime Not enough land to spread Freezing drainfields, mound systems Many new SSTS (over 600,000 in MN). Why not?.

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ACCEPTING SEPTAGE at your WWTP

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  1. ACCEPTING SEPTAGEat your WWTP Kay Curtin MPCA- St. Paul

  2. Why are treatment plants taking more septage? • Mandatory pumping – every 3 years • Don’t want to lime • Not enough land to spread • Freezing drainfields, mound systems • Many new SSTS (over 600,000 in MN)

  3. Why not? • Extra solids to deal with • Plant capacity? • Possible plant upsets • More oxygen needed • More staffing needed • More sampling needed

  4. Why accept septage? • Protect groundwater and surface water • Better solids removal than in the past • More activated sludge plants • The hauler is on the village board • $$$ (maybe)

  5. What is in that septic tank? • 50X more concentrated than WW influent • 8,000 mg/L BOD • 15,000 mg/L TSS • Lots of pathogens • Household chemicals?

  6. What’s in it? • Surfactants • Greases and oils • Lots of large solids and debris • Organics: 1,000 gal = 35,000 gal WW influent • Odor – Hydrogen Sulfide

  7. What’s NOT in it? • Oxygen

  8. The BIG BALANCING ACT • Trying to prevent ground water and surface water contamination from septage while maintaining high quality WWTP effluent while keeping operating costs to a minimum

  9. Prep Work Do it yourself or hire a consultant

  10. First Things First • Try to find out: • How much • How frequently • What time of day • The strength (BOD, TSS, NH3, TP) • Other constituents (metals, organics, etc.)

  11. Look at your type of plant and layout • Activated sludge or pond • Preliminary and primary treatment • Biosolids treatment • Receiving station

  12. Problems with adding septage into a sewer manhole: • Solids and grease buildup in sewers • Corrosion in sewers • Odors • Sampling and metering • Sneaking loads into remote sewers

  13. Determine your plant’s excess capacity

  14. Calculating excess capacity • Calculate your present plant loading of BOD and TSS • Remember: MGD x lbs. x 8.34 lbs./gallon • Find your plant’s BOD and TSS design loading in pounds per day • Subtract

  15. Divide those two numbers by the appropriate loading from the table below. The smallest value is the maximum your plant can treat.

  16. Plant flow? • Flow must be at least 10 X septage • Plants >2 MGD handle slug loads best

  17. NPDES permit limits? • Do you have extremely low phosphorus, nitrogen or metals limits? • Guess who is responsible if someone dumps high loadings into your plant!

  18. Preliminary Solids Removal? • How good is your solids removal? • Can it handle grit and rag removal? • Adequate ventilation? • All parts – stainless steel?

  19. SOLIDS REMOVAL

  20. Things to consider • Do you have flow equalization? • Do you have adequate metering? • Can you afford a receiving station? • The time to put one in is during an upgrade • Are there failing septics in your area?

  21. Things to consider • Look at your sludge handling facilities • Septage can add 60 pounds of sludge per 1,000 gallons • Do you have the staff/equipment/land to handle it? • May add directly to anaerobic digester

  22. Staffing Capabilities? • Maintenance • Lab • Evening hours • Accounting and billing

  23. Know your haulers • Check references

  24. System Upgrades? • Good time to think about a receiving station • Failing septic systems?

  25. Legal issues • Get your ducks in a row, legally speaking • Formal agreements • Responsibility and Liability • Check your NPDES permit • Liability • Consult w/city attorney • Liability

  26. Items to ban: • Adhesives • Antifreeze • Medications • Cleaners • Gasoline and motor oil • Paint • Pesticides • Solvents • Wood preservatives • Meth lab cleanup waste

  27. Talk to the neighbors Give them a “heads up”

  28. Develop Charges Will you charge according to: • city sewer rates? • treatment costs? • neighboring facilities?

  29. MCES - website of their current charges: • http://www.metrocouncil.org/environment/IndustrialWaste/news_rates.htm#LC

  30. Have a meeting with info in hand • Your cost estimates • How you will keep track of loads, sample, etc. • Your expectations

  31. Weigh your options carefully

  32. Monitoring • Keep on top of it • Meter or keep track of loads • Know where it’s coming from • Sample and test – keep samples until waste is through the plant • Run a clean operation

  33. Let rates reflect your cost changes • Review at least annually • Keep up the PR

  34. Kay Curtin MPCA – St. Paul 651-757-2299 kay.curtin@gmail.com THANK YOU!

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