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EHST 3370 Exam 1 Study GuideHomework (Due 12816)1) What are t.docx
- 1. EHST 3370 Exam 1 Study Guide/Homework (Due 1/28/16) 1) What are the five components of an onsite wastewater system, and what function(s) does each component serve? 2) What are some typical concentrations of total nitrogen (mg/L), total phosphorus (mg/L), and BOD5 (mg/L) for 1) wastewater effluent and 2) septage? 3) What are the five principles of On-site Wastewater Treatment? 4) Why are long, narrow septic system trenches preferred over wider, short trenches? 5) If effluent surfaces in a yard, why is it a concern? 6) How can wastewater from an onsite system impact ground water quality? 7) What coastal environmental problems may be partly linked to wastewater management (other factors, but wastewater can contribute also)? 8) On average, how much water does each person use per day? 9) What is the difference between pollutant concentrations and pollutant loadings? 10) How does the concentration of organic matter in water affect dissolved oxygen? 11) How does temperature affect dissolved oxygen? 12) What is the difference between total suspended solids and total dissolved solids?
- 2. 13) What is the difference between volatile and fixed solids? 14) If most E. coli and fecal coliform bacteria are not harmful to humans, why do we test for them and get concerned if they are found in the water samples? 15) How does the speciation of nitrogen (form) affect it’s mobility in soil (NO3 in comparison to NH4)? 16) What forms of nitrogen are dominant in septic tanks? 17) What are FOGs and how do they affect septic systems? 18) List three things required in the report to obtain a permit to apply septage to a field? Who must develop the report? 19) What are three methods of land application of septage? 20) List three potential negative issues with land application of septage. 21) List three factors for determining where septage can be land applied. 22) How is septage typically treated (with what material) before land application? 23) What are the soil depth requirements to apply septage on fields with group I, II and III soils? 24) What are the setback requirements for septage application sites and property lines, occupied homes, and streams? 25) What is the difference between BOD and COD? 26) List 3 designated water resource uses 27) What are 3 typical pollutants that cause water use impairment?
- 3. 28) How many onsite systems are in use in NC? How many new systems are installed each year in NC? How many systems are repaired each year in NC? 29) Define biomat, and list one positive and one negative associated with a biomat in terms of system performance. 30) Which component of an onsite system is most important for wastewater treatment? Biosolids Citation Modified from: Lesikar, B.J., A. Kenimer and D.Gustafson. 2005. Septage- Biosolids – PowerPoint Presentation. in (M.A. Gross and N.E. Deal, eds.) University Curriculum Development for Decentralized Wastewater Management. National Decentralized Water Resources Capacity Development Project. University of Arkansas, Fayetteville, AR. SeptageSeptage is a product of onsite wastewater treatmentIncludes solids and liquids in septic tankCollected through pumping of septic systems
- 4. Septage Characteristics Characteristics of Septage: Metals Choices for Septage Handling Land ApplicationMost popular methodWWTPSecond most popular method Septage Treatment PlantVery rare due to high costs Wastewater Treatment PlantTransfers treatment to different entityTreatment plant must have capacity for additional loadingFollow receiving facility’s guidelines for discharging Methods for Land ApplicationSurface Box Spreader, Tractor Towed Slurry Irrigation Tank Truck Tank Wagon, Tractor TowedSub-Surface
- 5. Plow- Furrow- Cover Injection from Tank Wagon or Truck Injection from Crawler Tractor Criteria for Selecting Application EquipmentSludge Moisture ContentSludge QuantityType of Storage SystemApplication RateApplication Schedule (frequency, season)TopographyTransport DistanceCost and Availability Septage Application Methods vs. Solids ContentSolids ContentApplication Method1-6%Slurry Irrigation4-10%Tank Wagon or Tank Truck; Surface Spread4-15%Tank Wagon or Tank Truck; Soil Injection25-80% Box Spreader40%+Spreader Truck Direct InjectionIncorporate septage as passing across fieldTank trucks can inject septage into soilDrag hose can supply liquid to an injection implement
- 6. Liquid Spreading Spreading with the tank truck hauling septagePan at end of outlet spreads liquid on ground behind truck Semi Solid Material SpreadingLoad into a spreaderDistribute material onto the land surface Potential Septage IssuesPerceptionsNutrientsMetalsEmerging ContaminantsOdorsPublic HealthPathogensVectors The solution for PerceptionProfessionalismRecordsProceduresTimingLocationsE ducationYouPublic Land Application SitingApplication sites must be permitted and thus meet permit criteriaSlopeSetbacksSoil typeWater table Application Site Permit Requirements Report RequirementsReport must be prepared by licensed soil
- 7. scientist, professional geologist, or professional engineer. Soil Fertility and Metals Analysis *Acidity *Base Saturation *Calcium *Cation Exchange Capacity *pH *Phosphorus *Potassium *Sodium *Exchangeable Sodium Percentage *Humic Matter Percentage *Total Metal Analysis *Arsenic *Cadmium *Copper *Lead *Nickel *Selenium *Mercury- if biosolids from treatment plant NC Department of Ag & Consumer Services Division of Agronomic Services provides analysis Sampled annually and for initial permit. Soil Profile Descriptions * Horizon (soil layer) thickness * Soil color- hue, value and chroma with Munsell color chart * Soil texture- sand/silt/clay% estimates using texture by feel method * Soil structure- aggregation category of soil (granular, blocky,
- 8. platy, etc.,) * Restrictive zones- hard pans present? * Wetness conditions- high water table or poor internal drainage Profile descriptions to 4 ft, unless application rate is > 125,000 g/acre/yr, then 6ft Soil Wetness Conditions Group I soils: suitable if SHWT is greater than 36” below point of application Group II soils: suitable if SHWT is greater than 24” below point of application Group III soils: suitable if SHWT is greater than 18” below point of application Setbacks Surface Water Classifications Soil Map Scale 1” = 400’ or less, major soil mapping units North arrow, legend, setbacks
- 9. Tensiometers Time Domain Reflectometry (TDR) Nutrient Management The solution for NutrientsCWA Section 503 Based Loading ratesDaily10,000 gal/acreAnnualCrop need Other Conditions Septage can make YOU sick The Solution for Public Health: Pathogen and Vector ControlLime StabilizationProper
- 10. timingCompostingDigestionIncorporationCovered Storage Lime TreatmentPathogen ControlDisease causesVector ControlMovementOdor MitigationSoil Conditioning One Method for Lime TreatmentPump TankADD LIMECheck pHReaction TimeLand Apply Lime additionPowderSlurry Check pH How Much Lime?25 # per 1,000 gallonsStronger waste more limeCarry over in the tank
- 11. How long for Reaction?30 minutes after mixing above pH of 12 or greaterSome States require 2 hours Odor Management Use Stabilized Sludgee.g., Composting, digestion, lime treatment Minimize Stockpiling Low Application Rate (surface) Soil Injection or quickly incorporate after surface application Field Location (distance, direction) Benefits of Good Septage Land Application PracticePerceptionOdor reductionSoil treatmentPathogen reduction Septage Treatment PlantUsually process septage for land applicationRemove grit and debris from septageTransfer
- 12. products to other vehicle for transport Effluent Sewer Land ApplicationSolids Landfill Land ApplicationGrit Landfill SummarySeptage land application is generally the first choice for management Public Health Protection Nutrients are beneficially reused Lime stabilization is a simple and cost- effective pretreatment for land application Table 3. Characteristics of Septage: Conventional Parameters Concentration (mg/L) Parameter
- 13. Average Minimum Maximum Total solids 34106 1132 130475 Total volatile solids 23100 353 71402 Total suspended solids 1286
- 14. 2 310 93378 Volatile suspended solids 9027 95 51500 Biochemical oxygen demand 6480 440 78600 Chemical oxygen demand 31900
- 15. 1500 703000 Total Kjeldahl nitrogen 588 66 1060 Ammonia nitrogen 97 3 116 Total phosphorus 210
- 23. 0.0001 0.742 EPA (1994) Water Quality Citation Modified from: Kenimer, Ann L., J. Villeneuve and S. Shelden. 2005. Fundamental Concepts: Water Quality - Power Point Presentation. in (M.A. Gross and N.E. Deal, eds.) University Curriculum Development for Decentralized Wastewater Management. National Decentralized Water Resources Capacity
- 24. Development Project. University of Arkansas, Fayetteville, AR. Standard Methods for the Analysis of Water and Wastewater. American Water Works Association and the American Public Health Association.EPA Methods and Guidance for the Analysis of Water. US Environmental Protection Agency. Water PollutionWater Pollution: any condition that adversely affects the quality of streams, lakes, oceans, or groundwater Unpolluted water has a wide diversity of aquatic organisms and contains enough dissolved oxygenPolluted water inhibits the growth of aquatic organisms Water Quality TermsWater resource usesSwimmingBoatingFishing / fish consumptionShellfish harvestingAquatic habitatWater supply HumansAnimals Water use impairment- the inability of a resource to meet it’s intended usesFor example, an estuary is impaired when high levels of bacteria ban the harvesting of oysters.
- 25. Importance of Organic MatterOrganic material consumes oxygen in water during decompositionOrganic material can cause taste and odor problems in recreational and drinking waterSome material may be hazardous Dissolved OxygenDissolved oxygen is oxygen that has been incorporated into waterMany aquatic animals require it for their survival < 2 mg/L most fish cannot survive, 4+ mg/L is okOften measured in-situ with field meters and loggers Dissolved Oxygen There are two important factors that can influence the amount of dissolved oxygen presentWater temperatureGreater saturated DOOrganic matterIf oxygen is available, organic material requires oxygen to decomposeOrganic material may also decompose in the absence of oxygenMore organic material requires more DO, and will tend to deplete water of DO
- 26. Biochemical Oxygen DemandBiochemical oxygen demand, or BOD is the amount of oxygen used by organisms during the breakdown of organic materialBOD is considered an indirect measure of the organic content of a sampleBOD analysis is done under these conditions:Must be in the darkMust be at 20ºCMust have an excess of nutrients BOD5 ProcedureCollect sample in a bottle, once in lab add nutrients, maybe seed (microorganisms), and oxygenated distilled waterMeasure initial DOIncubate sample for 5 days at 20o C in darkMeasure final DOThe BOD5 is directly related to the amount of DO used up over the 5-day period BODBODt = BOD at t days (mg/L)DOi = Initial DO (mg/L)DOf = Final DO (mg/L)Vs = Volume of sample (L)Vb = Volume of BOD bottle (L)
- 27. Chemical Oxygen Demand (COD)COD is the equivalent amount of oxygen needed to break down organic matter and oxidize nitrogen compounds using strong oxidizing agentsAnother means of measuring oxygen demand needed to oxidize organics and reduced nitrogenous compounds Faster than BODAlways higher than BODCOD is much higher than BOD in raw wastewatersCOD:BOD ratio is usually less than 2:1 in treated effluentsCOD:BOD ratio is dependent on circumstances and reduces with treatment Total Organic CarbonTotal organic carbon, or TOC, is the amount of organic carbon bound in a sample. Fats, Oil, and GreaseGenerally listed under one heading called FOG (fats, oils, and grease) as it is often not important to know the exact make-up of this group of components Solids Cause many problems:May clog distribution systems, pipes, tanks, causing wastewater back-up in homeFill storage areas in trenchesReduce infiltrate rate of soil, and may cause surfacing of wastewater
- 28. Total Solid (TS)Total solids of a sample is the matter left behind after drying a sample of water at 105ºC There are two ways that solid materials may be classifiedSuspended solids and dissolved solids (size)Volatile solids and fixed solids (organic or mineral) SolidsTotal suspended solids are the part of the sample that may be caught with a 0.45 µm filterTotal dissolved solids are the part of the sample that will pass through the filter Total volatile solids is the portion of the sample lost after the sample has been heated to 550ºC. It is an approximation of the organic material presentTotal fixed solids is the portion that still remains after heating. It is an approximation of the mineral matter present SolidsThese categories may be combined:Volatile dissolved solids (VDS) (small, organic)Volatile suspended solids (VSS)
- 29. (large, organic)Fixed dissolved solids (FDS) (small, mineral)Fixed suspended solids (FSS) (larger, mineral) Nutrients Problems associated with excess nutrients: Causes an increase in productivity of aquatic plants (organic matter), leading to depleted DO levelsMay cause odor problemsExtra vegetation near surface may inhibit penetration of light into water NutrientsNitrogenPhosphorusRequired for plant lifeIn excess can promote too much plant life (algal blooms)Brackish waters : usually N limited (0.1 to 1 mg/L mg/L or greater may stimulate blooms)River in-stream processes reduce and transform N before reaching estuary, denitrification and plant uptake in marshes reduces NFresh waters: usually P limited (0.02 mg/L or greater may stimulate blooms)P often bound to soil particles and not available in fresh water systems, but P released when mixing with
- 30. * Chemistry of Nitrogen Nitrogen can exist in nine various forms in the environment due to seven possible oxidation states: Nitrogen CompoundFormula Oxidation StateOrganic nitrogenOrganic-N-3AmmoniaNH3-3Ammonium ionNH4+- 3Nitrogen gasN2 0Nitrous oxideN2O+1Nitric oxideNO+2Nitrite ionNO2-+3Nitrogen dioxideNO2+4Nitrate ionNO3-+5 Nitrogen Dynamics Nitrogen can undergo several transformations Adsorption of NH4+-N in the soil Volatilization of NH3-N in alkaline soils at a pH above 8.0 Nitrification and subsequent movement of NO3- -N towards the groundwater Biological uptake of both NH3-N/NH4+-N and NO3- -N Denitrification if the environmental conditions are appropriate
- 31. PhosphorusOriginates from weathering of igneous rock, soil leaching, and organic matter.Also anthropogenic sources include wastewater, fertilizer, and detergent (phosphate detergent has been banned)Commonly transported with sediment via erosion, but OSWS may contribute phosphorus to ground and surface waters if P-index of soil is high, and/or if P was bound by Fe oxides, and anaerobic and saturated conditions cause Fe3+ to become reduced to Fe2+ and leach, thus leaching P Fresh waters usually phosphorus limited- may cause eutrophication * Microbial OrganismServe many important purposes including degrading waste materialsSome of them may be dangerous to human health and must be removed from water Microbial OrganismsAerobic-perform best when waters are well aerated and contain relatively high concentrations of dissolved
- 32. molecular oxygen Anaerobic- perform best in conditions with little or no molecular oxygen Obtain needed oxygen from molecules that contain oxygen such as NO3, Fe(OH)3Prefer aerobic conditions but easily adapt to low oxygen circumstances Testing for Microbial OrganismsFecal coliform, E. coli, Enterococcus, total coliform counts are used as an indicator organismsThe samples are typically filtered, nutrient broths are added, the samples incubate for 24 hoursThe number of colonies that form are counted – colonies are proportional to how many microbial organisms are present in a sample Salts Problems associated with excess salt:High salt concentrations detrimental to plant growth and can damage crops Salt can damage equipment, especially some materials which react with the saltsElectrical conductivity (US/cm) often used to infer salt content (very conductive)
- 33. Specific Conductance/Electrical Conductivity uSiemens/cm at 25 C Measures electrical conductance due to dissolved substances in water per 1 cm path length at 25C Ranges uSiemens/cm at 25CDistilled water 0-2Rainfall 2-117 (average = 13 at Lewiston, NC)Sandstone headwater stream 50- 70Limestone stream 300-600Wastewater 1100+Salt water 35,000+ Can provide an indication of how long water has spent underground with minerals- more dissolved- higher SpC Metals Problems associated with excess metals:High metal content in wastewater or biosolids that are applied to agricultural fields can reduce crop growthMetals in high enough concentrations are pollutants and can be serious health risks.
- 34. TurbidityTurbidity is a measure of the clarity of water.Turbidity is influenced by the number of insoluble particles presentSediment and organics often cloud surface waters after stormsOften used to estimate suspended sediments (with calibration)Need many suspended sediment samples to relate to turbidity for a given riverTurbidimeterUnits - Nephelometric turbidity units (NTU) pHpH is the negative log of the hydrogen ion concentrationIt can have a major impact on biological and chemical reactionsThere is an inverse proportion of H+ and OH- ions, and the pH scale is logarithmic.pH of 6 has 10x more H+ ions in solution than pH 7, 100x more than pH 8, etc.,pH of natural waters may vary widely (6-9) due to organic acids (e.g. humic acids) or alkaline mineral deposits (e.g., limestone).Rainfall less than pH of 5 is considered “acid rain”Often measured with field meters AlkalinityAlkalinity is the capacity of water to absorb hydrogen ions without significant pH changeBicarbonates, carbonates,
- 35. and hydroxides are the three chemical forms that contribute to alkalinityLack of alkalinity can limit the nitrification rate of effluent, because when NH4 converts to NO3, the H is released and can lower pH unless there is sufficient buffering capacity (alkalinity). If the pH is too low, microbes will not nitrify the NH4. Major Pollutants Causing Stream Use Impairment Source: USEPA * Sediment, as mentioned before, is the major pollutant of concern in freshwater streams. Source: USEPA Major Pollutants Causing Estuary Use Impairment
- 36. * Nutrients and bacteria are the major pollutants of concern in estuaries. Treatment Efficiency Treatment Efficiency (Concentration Reduction) Efficiency = [(C in - Cout)/Cin ] 100 Where: Cin = Influent concentration (typically mg/L) Cout = Effluent concentration (typically mg/L) And Efficiency is expressed as a percentage (%) Concentration = mass/volume (mg/L) Treatment Efficiency (Load Reduction) Efficiency = [(L in - Lout)/Lin ] 100
- 37. Where: Lin = Influent load (typically kg/yr) Lout = Effluent load (typically kg/yr) and Efficiency is expressed as a percentage (%) Treatment Efficiency Load = concentration*flow (mg/day) mg/L * L/day b V s V f DO i DO t BOD - = 0500100015002000250030003500 Impaired Stream Miles Turbidity Low Dissolved Oxygen Fecal Sediment Pollutant
- 38. NC: 37,563 Stream Miles 010002000300040005000 Impaired Estuary Square Miles Low Dissolved Oxygen Bacteria Nutrients Pollutant USA: 26,847 Square Miles Survey EHST 3370 Wastewater Management Spring 2016 Unit 1:Introduction to On-site Wastewater Treatment and Disposal Systems *
- 39. Septic System Treatment and Disposal Mechanisms Septic Tank- settling tank where wastewater is stratified, liquid effluent exits tank, solids remainDistribution device to convey effluent to trenches 3) Drainfield trench is aerobic environment where wastewater is stored until it infiltrates the soil 4) Soil beneath trench is aerobic, and most pollutant transformation and removal occur 5) Setbacks- required horizontal distance from system to point of interest such as a surface water, well, property line, etc., 1 3
- 41. Distribution Box Plan-View of On-Site Wastewater Treatment and Disposal System Soil Soil * On-site Wastewater Treatment and Disposal Systems 25-30 % of US population use On-site systems
- 42. 50% of NC residents (4.5+ million people) use On-site (2 million systems in NC) 30,000 - 40,000 new systems/yr installed in NC ~7,000 repairs each year 60% Coastal NC residents use on-site Pitt County, 460/yr % Septic 10-25 26-40 >40 *
- 43. > 700,000 systems Wastewater, Water-Borne Diseases and Public Health
- 44. Raw Sewage Characteristics mg/L = milligrams per liter s.u. = standard units CFU/100 mL = Colony-Forming Units per 100 milliliters Adapted From: US EPA Onsite Wastewater Treatment Systems Manual, EPA/625/R-00/008, US EPA Office of Water, 2002ComponentRange of ConcentrationsTypical ConcentrationTotal Suspended Solids, TSS155 – 330 mg/L250 mg/LBOD5155 – 286 mg/L250 mg/LpH6 -9 6.5 Total Coliform Bacteria108 – 1010 CFU/100mL109 CFU/100mLFecal Coliform Bacteria106 – 108 CFU/100mL107 CFU/100mLAmmonium- Nitrogen, NH4-N4 - 13 mg/L40 mg/LNitrate-Nitrogen, NO3-N Less than 1 mg/LLess than 1 mg/LTotal Nitrogen26 – 75 mg/L60 mg/LTotal Phosphorus6 - 12 mg/L10 mg/L
- 45. * These parameters are typical for domestic sewage, but not for sewage from restaurants, commercial facilities, or other sources that are not residential. NC Design Flow = 60 g/d Water Use Characteristics
- 46. Microbial Waterborne DiseasePrior to the late 19th century, outbreaks of epidemic waterborne disease claimed heavy tolls in human lives and suffering.As late as the 1880s typhoid killed 75-100 people per 100,000 population in the US every year.Cholera was also a serious issue in the US in the 19th century.Contamination of waterways in the developing world continues to persist as the most pressing environmental health problem. Wastewater and Public Health Almost 5,500 people die every day due to fecal contaminated drinking water (developing nations). Wastewater and Public Health
- 47. Wastewater and Public Health Wastewater and Public Health Wastewater Pre-treatment Wastewater Pre-treatment Improving Tank Performance Principles of On-site Wastewater Treatment and Disposal I. On-site systems should ensure that the effluent is absorbed by the soil and does not come to the land surface or
- 48. flow directly into streams, rivers, lakes, the ocean or the groundwaterSewage contains pathogens, if the sewage remains below the surface direct exposure will not occur. If sewage surfaces, there are immediate public health concerns. On-site systems treat and dispose of wastewater, via the septic tank and soil beneath the trenches. For treatment to happen, wastewater must stay in soil beneath the surface and above the water table. Principles of On-site Wastewater Treatment and Disposal II. On-site systems should maximize the aerobic treatment of the sewage. 1) Aerobic treatment occurs in aerated soil beneath the drainfield trenches (unsaturated zone). 2) Aerobic treatment is the fastest and most complete treatment the effluent can receive in the soil. 3) On-site systems should be located where the effluent must travel the farthest distance before reaching the water table or saturated layers.
- 49. Wastewater Treatment Groundwater Septic Tank Aerated soil Wastewater Treatment 18” 12” Group II-IV Soils: Loams, clay loams and clays Group I Soils: Sands
- 50. Principles of On-site Wastewater Treatment and DisposalOn- site systems should apply effluent to the soil only in suitable and prepared treatment and disposal field.The treatment and disposal field includes trenches or beds lined with porous media, where effluent is discharged into via pipes with holes. The soil beneath the trenches/bed absorbs the wastewater. Septic system components (tank, distribution devices, pipes, etc.,) should not leak- may cause contamination. Systems should only be installed in areas with suitable soil and site conditions, as determined by trained professionals (EHS). Principles of On-site Wastewater Treatment and Disposal 4) Treatment and disposal field trenches should be designed to maximize the effluent contact with soil, thus improving treatment. 1) Long, narrow trenches provide more wastewater/soil contact area than shorter, wide trenches (Beds). 2 trenches - 50’ x 3’ x1’ 1 Bed- 50’ x 6’ x 1’
- 51. 1 1 1 1 1 3 3 6 Contact Areas Trenches = 500ft2 Bed = 400 ft2 Principles of On-site Wastewater Treatment and Disposal 5) Treatment and disposal field trenches should have level bottoms and should be level along their entire length to distribute effluent as evenly as possible. 1) Slanted or sloped trench bottoms will make effluent flow to the lowest area, possibly causing overload and ponding of wastewater to the surface. Biomat
- 52. FormationReduces infiltration ratePromotes unsaturated flowCan improve treatmentMay cause hydraulic failure Indicator Bacteria Conc. Near Septic SystemsCogger et al., 1988 Scandura and Sobsey, 1997Humphrey et al., 2011Conn et al., 2011Harris et al., 2013Relatively high concentrations adjacent to drainfields, and sandy, shallow soils more prone to bacterial loadings Indicator Bacteria Conc. in Surface Waters Adjacent to Septic SystemsBooth et al., 2003Ahmed et al, 2005Cahoon et al., 2006Harris et al., 2013 Previous Septic System Studies * North Carolina Environmental IssuesShellfish Waters (SA) – Over 1,157 acres of SA waters have closed since 1990 (NC DWQ, 2007)High bacteria concentrationsRecreational Waters- swimming advisories due to bacteria concentrations 46
- 53. advisories in 2006 due to excessive bacterial concentrations (NC DENR, 2007)More stringent coastal stormwater rules enacted in 2008Are septic systems efficient at reducing bacteria densities in wastewater before discharge to shallow groundwaters? * Previous Septic System Studies Nitrogen Concentrations in Groundwaters Beneath and/or Adjacent to Septic SystemsServing residential areas with shallow, sandy-sandy clay loam soils Carlile et al., 1981Corbett et al., 2002Reay et al., 2006*Del Rosario et al., 2014*Serving residential areas with deep, sandy soilsRobertson et al., 1991*Postma et al., 1992*Buetow, 2002*Humphrey et al., 2010* All studies showed higher N near systems than background. Some (*) showed higher than water quality standards for NO3- (10 mg/L).
- 54. * Previous Septic System Studies Phosphorous Concentrations in Groundwaters Beneath and/or Adjacent to Septic Systems Serving residential areas with shallow, sandy soils Corbett et al., 2002* Reay et al., 2006 Humphrey et al., 2014* Serving residential areas with deep, sandy soils Robertson et al., 1998* Postma et al., 1992 Humphrey and O’Driscoll, 2011* Elevated P concentrations relative to background conditions (3 or more times higher)
- 55. North Carolina Environmental IssuesEutrophic Conditions and Fish Kills in 1990’sNeuse River Nutrient Sensitive Waters Management Strategy30% N loading reduction from 1991-1995 baseline implemented in 1998Tar-Pamlico River Nutrient Sensitive Waters Management Strategy 30% N loading reduction from 1995 baseline implemented in 2000No increase in P loading from 1995 baselineLake Jordan Watershed StrategyNeuse, Tar –Pamlico and Lake Jordan Rules targeted most point and nonpoint sources of nutrients (agriculture, urban runoff, wastewater treatment plants), but not septic systems) Neuse River Foundation (2009) *