Onsite Wastewater Treatment Concepts Septic 101 Fred Bowers, Ph. D. New Jersey Department of Environmental Protection http://www.state.nj.us/dep/dwq/sep_site.htm Early Onsite Systems Did not use water 1
Cesspools Were invented when indoor plumbing and flush toilets increased water use Septic systems are an improvement over the cesspool 2
Septic Systems provide treatment Convert organic matter to inorganic nitrogen and carbon dioxide Settle out Solids But septic tanks still pollute to some extent. Param eter Concentration Suspended Solids (mg/l 300-150 BOD 5 (m g/l 150 Pathogens (col./100 ml) 10 6 Nitrogen (mg/l) 40 to 75 Phosphorus (mg/l 15 M etals & Toxic O rganics (mg/l Variable 3
The Soil provides additional treatment Conditions for bacterial/virus decay Ammonia converts to nitrate Metals and Organics are attenuated Odors are eliminated But soils cannot treat everything 10 pounds N per person-year enters the ground water Some phosphorus leaches out (sandy soils more so) Some pathogens break through Soils clog up with organic matter (Biomat) 4
A properly functioning septic system Pros No odors No surface ponding Cons Discharges nitrate to ground water Impacts quality of ground water entering streams Eventually clogs up the soil Well Water Table Stream or Lake A Failing Septic System Sewage ponds on surface Odors Creates rapid overland flow to streams May be too close to the water table Water Table Lake or Stream 5
What makes a system fail? Basically, the soil clogs up over time due to solids entering the leach field Bio-accumulation causes most system failures 6
What can make an onsite system perform better? Maintenance and pumping Effluent Filters Aerobic treatment Denitrification Systems Drip distribution systems Maintenance and Pumping Professional inspection of tank and leach field Pumping in accordance with table Tank size Household size (number of people) 1 2 3 4 5 6 8 1000 12.4 5.9 3.7 2.6 2 1.5 1 1250 15.6 7.5 4.8 3.4 2.6 2 1.4 Guidance for inspections is available online http://www.state.nj.us/dep/dwq/pdf/inspection_guidance.pdf 7
Reduce solids Filters Protect leach field from premature failure May allow smaller leach fields Aerobic Treatment Units Prolongs life of leach field Allows smaller leach fields Protects water quality Parameter Solids BOD Fecal Reduction 90% 90% 99% 8
Denitrification Systems Provide additional water quality protection Parameter Solids BOD Fecal Total N Reduction 90% 90% 99% >50% Drip Dispersal Places water into the root zone Maximum Nutrient uptake Minimum land disturbance Avoids mounds 9
Benefits of Onsite Systems Maximizes aquifer recharge Limits over-development of rural areas Forces people to adopt sustainable lifestyles Less costly than large public sewer projects Reduces pollutant loading of streams Advanced Technology Systems Can reduce nitrate loads to 2 mg/l Can reduce size of systems by >40% Can prolong life of systems by reducing bio-accumulation Can maximize water reuse and recharge 10
Benefits of Treatment on Bio-accumulation Drip dispersal of Primary Effluent less than 4.5 years in use. Drip dispersal of Treated Effluent less than 4.5 years in use. Onsite Systems can be the key to sustainable living and clean water in rural areas But they do require maintenance and management 11
Elements of a Comprehensive Management Program Public Involvement Board of Health Ordinances Periodic Inspections and Pumping Record-Keeping/ Reporting Financing Benefits of a Management Program Preserve Home values Ability to apply for low income loans and Federal funds Cost sharing when repairs are needed Better neighbors and neighborhoods Cleaner environment 12