Onsite/Decentralized Treatment is Important Nationally

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1 TITLE 5 SOIL EVALUATOR CERTIFICATION TRAINING ON-SITE SYSTEM BASICS PAUL SPINA, NEIWPCC Prepared for: Commonwealth of Massachusetts Department of Environmental Protection In conjunction with the New England Interstate Water Pollution Control Commission Onsite/Decentralized Treatment is Important Nationally 25% of population served 33% of new construction Small communities: 11% > 50% in suburbs or cities WHERE SEPTIC SYSTEMS ARE USED On-Site System Basics, page 1

2 WHY DO WE TREAT SEWAGE? Protect Public Health Environment Key issues evaluated while assuring protection Good treatment Economical Sustainable PUBLIC HEALTH Making people sick Good systems are the KEY to protection Well SEPTIC TANK & SOIL TREATMENT AREA Evolving goal: Disposal: effluent goes away. versus Dispersal: TREATMENT Public health AND environmental issues addressed Management: Disposal: often none at all versus Dispersal: System management is critical Groundwater Aerobic soil On-Site System Basics, page 2

3 DISPOSAL Goal: limit human contact Keep wastewater below ground Disposal options Public health Disposing of pathogens Treatment? Management: Install, flush and forget GOAL: TREATMENT AND DISPERSAL Starting to address environmental concerns in addition to public health concerns Technological advancements allow removal of: Pathogens Solids Nutrients System management is vital to treatment Goal is now DISPERSAL Hydrologic cycle is a key component of this Septic System HYDROLOGIC CYCLE Precipitation (rain, snow, etc.) Wastewater Input Water Table Runoff Stream Evaporation & Transpiration Ground Water Impermeable Layer On-Site System Basics, page 3

4 ALL WASTEWATER MUST BE TREATED WASTEWATER SOURCES User Domestic Commercial Industrial Do you mind? DOMESTIC WASTEWATER Dishwasher, 1.4% 1 gpp/d Other, 2.3% 1.6 gpp/d Faucets, 15.7% 10.9 gpp/d Leaks, 13.7% 9.5 gpp/d Washing Machine, 21.7% 15 gpp/d Toilet, 26.7% 18.5 gpp/d Shower, 16.8% 11.6 gpp/d Bath, 1.7% 1.2 gpp/d Average domestic water use ranges from 45 to 60 gallons/day/person Composition varies from person to person, family to family, and system to system After Mayer et al On-Site System Basics, page 4

5 THE PROBLEM BIOLOGY - PATHOGENS Bacteria Cholera Typhoid Salmonella Shigella Water-borne diseases Fecal coliform Used as an Indicator Virus Hepatitis A Acute gastroenteritis Polio Parasites Protozoa o Amoebiasis o Giardia o Cryptosporidiosis Roundworm LEVEL OF RISK It depends: On how well the system was designed, installed, and maintained Is wastewater draining to or surfacing in the yard? Installed in an area with high groundwater levels? Close to a drinking water well? Are effluent screens maintained (cleaned)? If system is designed, installed, and maintained properly, risk to an ordinary individual is minimal WHAT IS AN ONSITE WASTEWATER TREATMENT SYSTEM? 1. Wastewater Source 2. Collection and Storage 3. Pretreatment components 4. Final Treatment and Dispersal components On-Site System Basics, page 5

6 Source Septic Tank SYSTEM BASICS CONVENTIONAL SYSTEM COMPONENTS Distribution Box Drain field Soil HOW DOES A SEPTIC SYSTEM WORK? What takes place in the septic tank? Gravity and physics take over Heavy materials settle Light materials float Dissolved materials, colloidal particles and fine suspended solids pass through and along to next stage SEPTIC TANK: PRIMARY TREATMENT Job of tank: catch the solids Water tight tank, inlet, inlet baffle, inspection pipes, manhole, outlet baffle, outlet pipe Layers in tank Scum layer: floating soap, grease, toilet paper, etc Liquid layer: water, liquid, and suspended solids Sludge: heavy organic and inorganic materials in the bottom of the tank Anaerobic bacteria breakdown organic solids On-Site System Basics, page 6

7 SEPTIC TANK SEPTIC TANK PARTIALLY TREATED EFFLUENT NEXT PASSES ON TO THE DISTRIBUTION BOX ( D-BOX ) A D-Box is designed and installed to distribute partially treated sewage effluent evenly across the SAS (Soil Absorption System) Effluent disperses into soil On-Site System Basics, page 7

8 DISTRIBUTION BOX (D-BOX) EFFLUENT FROM THE D-BOX NEXT GETS DISTRIBUTED TO THE SOIL ABSORPTION SYSTEM (SAS) WHAT IS A SOIL TREATMENT AREA? A soil treatment system: Safely treats, disperses and recycles wastewater All the treatment and dispersal takes place on site or close by Natural physical, chemical, and biological processes occur primarily in the soil On-Site System Basics, page 8

9 Components of a typical on-site sewage disposal system, utilizing trenches. HOW DOES A SAS WORK? What happens in the drain field and in the soil? Major source of treatment Filtering action Bacteria in soil Must be aerobic for maximum treatment CONVENTIONAL SYSTEM TREATMENT AND DISPERSAL COMPONENT Vent & Observation Pipe Finished Grade Observation Tail-piece Minimum Vertical Separation Gravel or Chamber 4 Inch Gravity Distribution Pipe High Groundwater or Bedrock On-Site System Basics, page 9

10 SOIL ABSORPTION FIELD TSS* and BOD* strongly reduced: Organic Matter + O 2 CO 2 + H 2 O + energy High degree of treatment under aerobic conditions TSS and BOD reduced to background levels * TSS = Total Suspended Solids * BOD = Biological Oxygen Demand PROCESS WHEN WASTEWATER ENTERS SOIL Biomat forms over time Unsaturated conditions are ideal Aerobic organisms treat the wastewater AEROBIC ZONE Well Groundwater Aerobic environment in soil On-Site System Basics, page 10

11 BIOMAT GENERAL GRAPHIC OF ACTIVITY IN SOIL Viruses BOD TSS Bacteria Nutrients Nutrients Unsaturated aerobic zone Well Groundwater TREATMENT IN THE SOIL Organisms that remove most contaminants work best when they: Are in an aerobic (oxygenated) environment Are in moist (unsaturated) but not wet (saturated) soil Are in a warmer environment Have surfaces on which to attach and live Have a consistent source of food Are not exposed to toxins On-Site System Basics, page 11

12 UNSATURATED SOILS Pores are filled with Air & water along the soil particles SATURATED SOILS Pores are filled with water TREATING PATHOGENS They attach to the soil particles They are attacked by soil organisms The soil is a very effective treatment media On-Site System Basics, page 12

13 OTHER SYSTEMS Pressure Distribution Drip dispersal Recirculating Sand Filter Grey water systems Shared systems I/A Technology SEPTIC SYSTEM INCORPORATING PRETREATMENT TITLE CMR The State environmental code: Standard Requirements for siting, construction, inspection, upgrade and expansion of on-site sewage treatment and disposal systems and for the transport and disposal of septage. water/wastewater/septic-systems-title-5.html Most recent major updates to Title 5 were done in January, 2014 Design flow changes made in Sept On-Site System Basics, page 13

14 A student assessing soil horizons and layers in a soil test pit at a SE cert. class field session. SOIL IS A VERY EFFECTIVE TREATMENT MEDIA, AND TREATMENT LEADING TO IMPROVED PUBLIC AND ENVIRONMENTAL HEALTH IS THE MAIN GOAL! END Thank You! On-Site System Basics, page 14