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1 Charlie Humphrey, PhD, Assistant Professor of Environmental Health Sciences at East Carolina University 2 Michael O’Driscoll, PhD, Associate Professor.

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Presentation on theme: "1 Charlie Humphrey, PhD, Assistant Professor of Environmental Health Sciences at East Carolina University 2 Michael O’Driscoll, PhD, Associate Professor."— Presentation transcript:

1 1 Charlie Humphrey, PhD, Assistant Professor of Environmental Health Sciences at East Carolina University 2 Michael O’Driscoll, PhD, Associate Professor of Geological Sciences at East Carolina University 3 Jonathan Harris, MA, Environmental Health Sciences Research Technician at East Carolina University Fecal Indicator Bacteria in Groundwater Adjacent to Three On-site Wastewater Treatment Systems in the North Carolina Coastal Plain

2 What is Next? Overview of on-site wastewater treatment systems and fecal indicator bacteriaOverview of on-site wastewater treatment systems and fecal indicator bacteria Research questionsResearch questions MethodsMethods Results and discussionResults and discussion SummarySummary QuestionsQuestions

3 Water Quality and On-site Wastewater Treatment Systems Bacteria Concentration Reductions Filtration, die off, predation, adsorption, dilution and dispersion Filtration, die off, predation, adsorption, dilution and dispersion 2 million OWS in NC, 60% of coastal NC use OWS 2 million OWS in NC, 60% of coastal NC use OWS OWS treat effluent with elevated fecal indicator bacteria (FIB) concentrationsOWS treat effluent with elevated fecal indicator bacteria (FIB) concentrations E. coli (10 4 to 10 6 MPN/100 mL) E. coli (10 4 to 10 6 MPN/100 mL) Enterococci (10 3 to 10 5 MPN/100 mL) Enterococci (10 3 to 10 5 MPN/100 mL) Total coliform (10 6 to MPN/100 mL) Total coliform (10 6 to MPN/100 mL) (US EPA, 1986)

4 Onsite Wastewater Treatment Systems Septic Tank Distribution Box Trench and Soil

5 On-site System Technologies Conventional OWS with Distribution Box Pump to Conventional OWS with Distribution Box Low Pressure Pipe (LPP) OWS LPP systems can be installed on sandy sites with less soil depth in relation to conventional OWS. Also, LPP systems typically require 25-30% less area than conventional trench OWS.

6 Biomat Influence on Wastewater Distribution (Hoover et al., 1996) (Loudon et al., 2005)

7 Research Questions Is there a more even distribution of FIB in groundwater beneath a LPP system in comparison to a pump to distribution box system?Is there a more even distribution of FIB in groundwater beneath a LPP system in comparison to a pump to distribution box system? What are the treatment efficiencies (FIB concentration reductions) at 2 large OWS and one residential OWS?What are the treatment efficiencies (FIB concentration reductions) at 2 large OWS and one residential OWS?

8 Methods

9 Monitoring Networks FIB comparisons and environmental readings including pH, DO, specific conductivity, depth to water, and temperature

10 Methods

11 Pitt County Residential Site Site Install Date Septic Tank Capacity (L) Max Design Flow (L/d) Distribution Device Dispersal Area (m 2 ) Vertical Separation (m)Soil Series Residential1998/ D-box151< 0.2 mGoldsboro/Lynchburg

12 James Smith Elementary SiteInstall Date Septic Tank Capacity (L) Max Design Flow (L/d) Grease Trap (L) Pump Tank (L) Distribution Device Dispersal Area (m 2 ) Vertical Separation (m)Soil Series JWS198737, ,144 D-box (2)892> 3 mAutryville

13 West Craven High SiteInstall Date Septic Tank Capacity (L) Max Design Flow (L/d) Grease Trap (L) Pump Tank (L) Distribution Device Dispersal Area (m 2 ) Vertical Separation (m)Soil Series WCHS199973,827 11,340 LPP (2)1115> 1 mTarboro

14 Groundwater FIB Spatial Distribution (JWS) Groundwater FIB Concentrations Fronts and ends of trenches; Field 1 and Field 2

15 Groundwater FIB Spatial Distribution (WCH) Groundwater FIB Concentrations Fronts and ends of trenches Field 1 and Field 2

16 FIB Treatment (Residential Site) FIB Comparisons Septic Effluent, Background, Drainfield Groundwater, Down-gradient, Stream

17 FIB Treatment (JWS) FIB Comparisons Septic Effluent, Background, Drainfield Groundwater, Down-gradient, Spring, Stream

18 FIB Treatment (WCH) FIB Comparisons Septic Effluent Background Groundwater Drainfield Groundwater Down-gradient Groundwater Surface Water Standards

19 Results and Discussion

20 Groundwater FIB Spatial Distribution Geometric Mean Enterococci F1-F = 336 MPN/100 mL F1-E = 1329 MPN/100 mL Fronts = 110 MPN/100 mL Ends = 445 MPN/100 mL F1 = 667 MPN/100 mL F2 = 73 MPN/100 mL F1 = 820 MPN/100 mL F2 = 106 MPN/100 mL p = 0.05 p = p = p = *More even distribution of Enterococci in GW at WCH

21 Groundwater FIB Spatial Distribution Mean E. coli F1-F = 1 MPN/100 mL F1-E = 7 MPN/100 mL Fronts = 1 MPN/100 mL Ends = 5 MPN/100 mL p < 0.10 *More even distribution of E. coli in GW at WCH

22 Groundwater FIB Spatial Distribution Geometric Mean Total Coliform F1 = 2007 MPN/100 mL F2 = 1178 MPN/100 mL p < 0.10 *More even distribution of total coliform in GW at WCH in GW at WCH

23 FIB Treatment at Schools Treatment Efficiency (%) Tank-DF Tank-Spring Tank-DF Tank-Spring Enter E. coli >99.99 >99.99 Total C Enter and Total C. (r =0.446, p = 0.011) Treatment Efficiency (%) Treatment Efficiency (%) Tank-DF Tank-Down Gradient Tank-DF Tank-Down Gradient Enter E. Coli >99.99 >99.99 Total C Enter and Total C. (r = 0.328, p = 0.07)

24 FIB Treatment at Residence Residential Enterococci Treatment Enterococci Treatment Tank-Down Gradient = 37.13% E. coli Treatment E. coli Treatment Tank-Down Gradient = 99.88% Correlation between E. coli and Enterococci r = 0.52, and p = 0.018

25 Physical and Chemical Parameters JWS Specific Conductivity (µS/cm) pHTemp (C°) Depth to Water (m) Field 1753 (246)6.37 (0.57)18.3 (1.1)4.56 (0.91) Field 2547 (237)6.89 (0.75)18.9 (1.1)6.21 (1.02) Front547 (204)6.45 (0.80)18.4 (0.9)4.92 (1.25) Ends754 (268)6.78 (0.58)18.8 (1.2)5.85 (1.15) Background98 (51)5.12 (0.65)18.1 (0.5)4.32 (0.31) Tank1057 (387)7.31 (0.26)17.8 (2.9) Down Gradient620 (69)7.23 (0.27)17.5 (0.8)0.34 (0.02) Spring445 (29)6.91 (0.37)18.2 (0.6) Upstream144 (12)7.22 (0.25)13.7 (1.1) WCH Specific Conductivity (µS/cm) pHTemp (C°) Depth to Water (m) Field 1312 (401)5.97 (0.65)16.4 (2.1)1.76 (0.16) Field 2550 (302)6.53 (0.34)16.7 (1.8)1.62 (0.11) Front521 (327)6.32 (0.55)16.6 (2.0)1.69 (0.16) Ends340 (397)6.17 (0.63)16.4 (1.9)1.69 (0.16) Background49 (12)6.56 (0.99)15.5 (2.2)1.53 (0.31) Tank1196 (432)6.91 (0.28)17.9 (3.5) Down Gradient710 (212)6.53 (0.22)17.2 (1.5)1.44 (0.13) Residence Specific Conductivity (µS/cm) pHTemp (C°) Depth to Water (m) Up Gradient181 (44)5.0 (0.6)18 (5.5) Tank855 (183)6.5 (0.2)18.4 (4.6) Down Gradient326 (132)6.2 (0.2)17.8 (5.9)< 0.20 Stream150 (19)6.4 (0.1)14.6 (8.0) SC and Enterococci (r = 0.428, p = 0.007) SC and Enterococci (r = 0.387, p = 0.014) SC and Total Coliform. (r = 0.534, p = 0.001) JWS SC Trends F1 > F2 Ends > Fronts F2 > F1 Fronts > Ends SC Trends All Sites Tank > DF > DG/Spring > Stream WCH SC Trends

26 Summary A more even distribution of FIB in groundwater beneath the LPP in comparison to pump to conventional systemA more even distribution of FIB in groundwater beneath the LPP in comparison to pump to conventional system All 3 systems were less efficient at reducing enterococci concentrations relative to the other FIBAll 3 systems were less efficient at reducing enterococci concentrations relative to the other FIB The OWS at JWS and WCH were more efficient at reducing FIB in comparison to the residential OWS possibly because of the limited vertical separation at the residential OWSThe OWS at JWS and WCH were more efficient at reducing FIB in comparison to the residential OWS possibly because of the limited vertical separation at the residential OWS Specific conductivity was correlated to some of the FIB, and generally showed similar trends with regards to FIBSpecific conductivity was correlated to some of the FIB, and generally showed similar trends with regards to FIB

27 Acknowledgements Matt Smith Guy Iverson Sarah HardisonCaitlin Van Dodewaard John WoodsAshley Williams Jim WatsonHannah Postma Eliot Anderson-Evans Amberlynne VanDusen NC WRRI NC Dept. of Environment and Natural Resources (319 Program) East Carolina University Coastal Water Resources Center Craven County School System Craven County and Pitt County Environmental Health Volunteers ECU Geological Sciences Department ECU Environmental Health Sciences Program

28 Questions?


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