Progress 10/01/99 to 09/30/04
Outputs
Objective 1. Failure rate literature for on-site wastewater treatment systems (septic systems) was assessed and reported as a keynote presentation at the ASAE national symposium. This identified additional unpublished studies and research reports. Drafts in preparation include (1) a failure rate study methodology manual and (2) a literature summary. A study of 320 randomly selected septic systems in Wake County, NC was completed and the report is undergoing peer review. A wet-season failure rate of 8-10% was observed with failure rates significantly related to landscape position and soil mapping units. System age, alone, did not substantially affect failure rates indicating that septic systems can be an effective long-term wastewater option if other factors are properly addressed. There was a significant interaction between siting factors (soils and landscape position) and some site maintenance conditions (crowning or shaping of the drainfield to shed rainwater, linear
depressions over trenches within the drainfield, surface run-on waters not diverted away from the drainfield) relative to failure rates. Failure rate was also significantly higher when structures such as outbuildings, sheds, garages, etc. were built over the system. Failure rate was related to vegetation type and degree of maintenance. There was a significant relationship between number of adults living in a home and failure rate, but no substantial effect due to the total number of occupants. Failure rate was greater in systems where the septic tank had been pumped. This was likely due to the mistaken thinking by homeowners that pumping the tank will correct an existing failing system. The practice of spreading laundry through the week rather than doing it all on one day did not change the failure rate significantly, but did effectively allow a doubling of total laundry water input (number of laundry loads). There was also a relationship between possessing educational material and/or
a copy of the system permit and how system user operated and maintained the septic system. Objective 2. A meeting was held with EPA headquarters office to determine the process for development and submittal of a project workplan. The workplan is currently under development for submittal to EPA and release of previously identified project funding. Sites were evaluated in northeastern North Carolina and a demonstration subdivision (North Meadows subdivision in Pasquotank County) has been identified for remediation of water quality and hydrology problems via implementation of the integrated water designs. The project website is at: http://www.soil.ncsu.edu/programs/septicsystem/ The project workplan elements under development include: develop a project management team and strategy, develop Integrated Water Design (IWD) concepts and identify technologies that address these concepts, demonstrate IWD and determine how they function in a community, develop and demonstrate technology
assessment tools, technology transfer, outreach and education.
Impacts
This study makes a first attempt at quantifying the potential nutrient loadings (such as nitrogen and phosphorus) due to on-site systems on both a river basin and sub-basin basis in North Carolina. Two major products are created. First, a state map identifying the densities of septic tank usage on a river basin/sub-basin basis. This allows the identification of potentially critical areas for further assessment of septic effluent impacts. Second an analysis of potential nutrient loadings by sub-watershed is developed. This analysis is developed from population values and therefore provides a more detailed display of the geographic distribution of potential loadings. Results obtained from this study can be compared with the potential nutrient loadings obtained from other non-point sources such as agriculture, forestry and urban land use.
Publications
- Amoozegar, A., S. Warren, C. Niewoehner, W. Robarge, M. Hoover, D. Hesterberg, and R. Rubin, 2004. Effect of Gray Water on Soil Hydraulic Properties. Tenth National Symposium on Individual and Small Community Sewage Systems. Proceedings of the March 21-24, 2004 conference, (Sacramento, California USA), ed. Kyle R. Mankin
- Pradhan, S., 2004. Predicting Nutrient Loadings and Fate and Transport of Nitrogen Derived from On-Site Systems, Ph.D. Dissertation, Soil Science Department.
- Pradhan, S., M.T. Hoover, R. Austin, and H.A. Devine, 2004. Potential nutrient loadings from on-site systems to watersheds. Tenth National Symposium on Individual and Small Community Sewage Systems. Proceedings of the March 21-24, 2004 conference, (Sacramento, California USA), ed. Kyle R. Mankin
- Deal, N.E., D.L. Lindbo, J. Tanner, and M.T. Hoover, 2004. Cost analysis of developing and operating small training centers. Tenth National Symposium on Individual and Small Community Sewage Systems. Proceedings of the March 21-24, 2004 conference, (Sacramento, California USA), ed. Kyle R. Mankin
- Hoover, M.T., 2004. Nutrient loadings from septic systems: Final Project report, EPA 319h Project EW9038. Soil scince dept, College of Agriculture and Life Sciences, North Carolina State University
- Pradhan, S., M.T. Hoover, R. Austin, and H.A. Devine, 2004. Potential nitrogen contribution from septic systems to North Carolina river basins. Soil Science Society of North Carolina Proceedings, Summary of 46th Annual Meeting in 2003, pg. 62-71.
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Progress 10/01/02 to 09/30/03
Outputs
The potential nutrient loadings from on-site septic systems to North Carolina river basins have long been ignored. Yet the potential for these systems to have significant impact exists. Based on the 1990 census, 1,365,536 households utilized on-site systems in North Carolina alone. This study developed a procedure to quantify the potential nutrient loadings from on-site systems within North Carolina watersheds and major sub-basins of those watersheds. Two analysis products were developed: 1) a distribution map of septic system densities by sub-watershed classified by USEPA density standards developed in 1977 and 2) a potential nutrient loading map. Both of these analyses used an area weighted GIS procedure to develop these estimates. Septic system density ranged from 5 to 20 systems km-2 at a river basin level and 2 to 115 systems km-2 at a sub-basin level. The Yadkin River basin had the highest potential nutrient loading of 3,283,069 kg yr-1 of which 2,879,885 kg
yr-1 was nitrogen loading and 403,184 kg yr-1 was phosphorus loading. Also, river basins that did not have the largest potential nutrient loadings on a complete watershed basis, had sub-basins with substantial potential nutrient contributions. For instance, the French Broad River basin potentially contributed 1,040,648 kg yr-1 of nutrients, an intermediate value on a full watershed scale. But at the sub-basin level, sub-basin FRB2 potentially contributed 562,114 kg yr-1 of nutrients, which was the second highest in the state at the sub-basin level. The Catawba, Cape Fear, Neuse, Yadkin, White Oak and French Broad River basins each had at least one sub-basin that potentially contributed more than 204,117 kg of nutrients yr-1. These high nutrient contributing sub-basins were primarily located in developing areas, along major highway corridors, in beach communities and in areas surrounding surface waters such as large lakes, sounds, rivers, beaches etc. Many of the beach communities
along barrier islands in North Carolina had very high densities of on-site systems and high potential nutrient loading rates, on a unit area basis (kg km-2). However, they did not have high total potential nitrogen loadings. The aerial extent of these sub-basins was generally so small that the cumulative potential nitrogen loading was not as great as within larger sub-basins despite the high densities. However, local impacts potentially could be substantial due to the relatively high densities of systems.
Impacts
This study makes a first attempt at quantifying the potential nutrient loadings (such as nitrogen and phosphorus) due to on-site systems on both a river basin and sub-basin basis in North Carolina. Two major products are created. First, a state map identifying the densities of septic tank usage on a river basin/sub-basin basis. This allows the identification of potentially critical areas for further assessment of septic effluent impacts. Second an analysis of potential nutrient loadings by sub-watershed is developed. This analysis is developed from population values and therefore provides a more detailed display of the geographic distribution of potential loadings. Results obtained from this study can be compared with the potential nutrient loadings obtained from other non-point sources such as agriculture, forestry and urban land use.
Publications
- No publications reported this period
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Progress 10/01/01 to 09/30/02
Outputs
The amount of N that septic systems provide to North Carolina's watersheds is unknown. Hence, state regulatory agencies have been interested in determining the potential impacts due to on-site systems across all NC watersheds, and particularly within the Neuse River basin. This project has analyzed in detail the flow dynamics and nitrogen removed (on a mass basis) from on-site systems serving selected homes in a small watershed within the Neuse River basin. Groundwater hydrology was assessed and a dilution model used to determine the effects of dilution on changes in nitrogen concentrations in wastewater-impacted ground water flowing from two homes. Then wastewater plumes were tracked as they traveled to the creek and adjoining riparian areas where nitrogen removal was evaluated on a mass basis. Redox potential, groundwater temperature, dissolved O2, and pH indicated conditions were conducive for denitrification to occur within the groundwater system. The extent of
nitrogen loss due to a combination of denitrification/plant uptake in the riparian zones was established. Then a GIS system was used to assess the cumulative potential nitrogen loading from septic systems within all of North Carolina's river basins and specifically in the Neuse River as well as it's 14 sub-watershed areas. The total potential nitrogen contributions due to septic systems across the state exceeds 30 million pounds of nitrogen per year without accounting for losses due to plant uptake, denitrification or in-stream removal. Use of septic systems ranged from less than 40% to more than 80% of the population of various watersheds across the state. Oftentimes, watersheds that had the lowest percentage usage of septic systems (compared to sewers) also had the highest density of septic systems and the greatest potential nitrogen impacts from them. This was due to the overall density of development in these areas that were adjacent to recreational waters and transportation
corridors. Density of septic system usage exceeded 40 systems per square mile (a level proposed by EPA as excessive) in the Catawba, White Oak and Pasquotank River basins. The total potential nitrogen contributions within the Neuse River basin exceeded 4 million pounds of nitrogen per year without accounting for potential losses due to plant uptake, denitrification and in-stream removal. This level is not insignificant compared to total potential nitrogen contributions due to urban lawn fertilization (3 million pounds per year) and agriculture (84 million pounds per year). In addition, the nitrogen from septic systems is primarily applied beneath the major rooting zone and would not be reduced substantially by plant uptake as occurs to approximately 50% of the applied nitrogen in urban lawn fertilization or agricultural uses. Further research is being conducted to refine this estimate of nitrogen due to septic system usage to better approximate what actually is delivered to the Neuse
River Estuary.
Impacts
The project will guide state regulatory officials in decision-making regarding needs for any reductions in nitrogen contributions from septic systems within nutrient sensitive watersheds.
Publications
- No publications reported this period
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Progress 10/01/00 to 09/30/01
Outputs
This ongoing study seeks to determine the amount of N that septic systems provide to the Neuse River basin by analyzing in detail nitrogen removed in a small watershed before the wastewater impacted ground water enters an adjacent creek and using GIS technology to extrapolate the findings throughout the larger Neuse River watershed. Groundwater hydrology was assessed by two students in the Hood's Creek sub-watershed and nitrogen dynamics evaluated to track the wastewater plumes to the creek and determine nitrogen removal. Wastewater plumes originating from the systems were delineated by examining groundwater Cl-, Na+, and Br--tracer concentrations. Redox potential, groundwater temperature, dissolved O2 , and pH were measured to determine if conditions conducive to denitrification existed in the groundwater. Water depths were measured every two weeks to determine if changes occurred in groundwater flow paths. Seepage samplers were installed in the stream bed to
determine groundwater flow rates into the stream, and to collect samples for nutrient analysis. Water samples were analyzed for N15 and O18 in NO3 to determine the NO3 source, and to determine if denitrification had occurred in the groundwater. The effect of dilution on changes in nitrogen concentrations were assessed prior to determining the actual loss of nitrogen on a mass basis. A third student is using GIS to assess the cumulative potential nitrogen loading from septic systems to the Neuse River and it's 14 sub-watershed areas. A new area normalization procedure for using GIS in conjunction with census data was developed to more accurately assess nitrogen contributions from on-site systems on a watershed basis.
Impacts
(N/A)
Publications
- Hoover, M.T. and D. Beardsley. 2001. The weight of scientific evidence. Small Flows Forum, Small Flows Quarterly, Winter 2001, Volume 2, No. 1. National Small Flows Clearinghouse, West Virginia University.
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Progress 10/01/99 to 09/30/00
Outputs
The Neuse River basin is plagued with excess nutrient enrichment from point and non-point sources. Agriculture has been blamed for contributing nutrients to ground- and surface waters, but contributions from on-site wastewater systems have not been assessed. This ongoing study seeks to determine the amount of N that conventional septic systems in New Bern, N.C. remove from wastewater before it enters an adjacent creek. Five sites were selected in the Hoods Creek watershed. Groundwater hydrology was determined, and piezometers were installed perpendicular to groundwater flow. Groundwater was sampled monthly, and wastewater plumes originating from the systems were delineated by examining groundwater Cl-, Na+, and Br--tracer concentrations. Redox potential, groundwater temperature, dissolved O2 , and pH were measured to determine if conditions conducive to denitrification existed in the groundwater. Water depths were measured every two weeks to determine if changes
occurred in groundwater flow paths. Seepage samplers were installed in the stream bed to determine groundwater flow rates into the stream, and to collect samples for nutrient analysis. Water samples were analyzed for N15 in NO3 to determine the NO3 source, and to determine if denitrification had occurred in the groundwater. Groundwater samples showed high concentrations of nutrients close to the septic systems and lower concentrations farther from the systems. The NO3 to Cl- ratios decreased with distance away from the septic systems, indicating that processes other than simply dilution were contributing to reductions in groundwater NO3 concentrations. The main reductions in N concentrations seemed to be attributable to dilution, but we hope to determine if denitrification decreased the mass of N that entered the creek from the septic systems.
Impacts
(N/A)
Publications
- Hoover, M.T. and D. Beardsley. 2000. Science and regulatory decision making. Small Flows Forum, Small Flows Quarterly, Fall 2000, Volume 1, No. 4. National Small Flows Clearinghouse, West Virginia University.
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Progress 01/01/99 to 12/31/99
Outputs
The project steering committee has been developed and has met twice. Stakeholder groups of extension, local health department and state regulatory officials met in both Craven and Wayne Counties to determine siting criteria for subdivisions for study of non-point source impacts, to preliminarily identify sites, and to conduct field reviews of those sites in preparation to selecting final study sites. After review of many sites and a comprehensive geologic assessment, the final subdivision study site was selected in Craven County. It is a small subwatershed feeding into a small tidal stream called Hoods Creek that empties into the Trent River. The watershed for Hoods Creek is primarily residential with some of the area in national forest and a small amount agricultural, at least historically. There are four major subdivisions that comprise the watershed surrounding Hoods Creek. Each was evaluated and two intensive study sites selected after preliminary geological,
soils and water quality analysis of selected wells, piezometers and a field survey of water quality in Hoods Creek itself. The first of the study sites has been completely instrumented and the second is partially instrumented. Water quality sampling has commenced at the first site. Secondary satellite sites have been identified for less intensive monitoring
Impacts
(N/A)
Publications
- No publications reported this period
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Progress 01/01/98 to 12/31/98
Outputs
The impact of bacterial septic tank additives on the rate of solids accumulation in septic tanks, microbial population in septic tanks and release of oxygen consuming substances (measured as BOD) and suspended solids from tanks was assessed in a replicated field experiment using a randomized complete block design that included a complete range of tank maintenance from poorly maintained to well maintained. Forty-eight, full-scale, functional septic tanks were monitored monthly to test three liquid bacterial septic tank additives (treatments) and one control (no additive) each replicated 12 times in a single-blind study. Analysis of variance and Dunnett t-test statistics showed there was no significant treatment effect on the rate of sludge accumulation in the septic tanks due to the use of additives. There was an inconsistent, transitory interaction during some months on the scum accumulation rate in the tanks, but no main treatment effect. There was no consistent
treatment effect on microbial populations, BOD or suspended solids due to the additives tested. We conclude, therefore, that the study does not show any practical long-term benefit of using the bacterial additves studied in this project. In separate efforts, risk-based site evaluation, design and management protocols for on-site systems, treatment performance standards for decentralized technologies, a failure analysis chart for troubleshooting failing on-site systems, hands-on training techniques, a performance assessment of an alternative technology for use of slowly permeable soils and an evaluation of wastewater management options for rural areas were developed.
Impacts
(N/A)
Publications
- Spooner, J., C.H. House, M.T. Hoover, A.R. Rubin, R. Silverthorne, Jr., S.J. Steinbeck, V. Harris, R.L. Uebler and B. Martin. 1998. Performance evaluation of innovative and alternative on-site wastewater treatment systems in Craven County, NC. Pgs. 458-469. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Dideriksen, R.R., D. Stephens, A. Adams, W.L. Arrington, Jr., S. Greene, M.T. Hoover and L.E. Young. 1998. Repair of failing systems workshop series. Pgs. 79-86. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Hoover, M.T., A. Arenovski, D. Daly and D. Lindbo. 1998. A risk-based approach to on-site system siting, design and management. Pgs. 66-78. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Hoover, M.T., D. Sievers and D. Gustafson. 1998. Performance standards for on-site wastewater treatment systems. Pgs. 346-355. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Hoover, M.T., A.R. Rubin and F. Humenik. 1998. Choices for Communities: Wastewater management options for rural areas. Publication number AG-585, North Carolina Cooperative Extension Service, North Carolina State University, Raleigh, NC
- Penninger, P.G. and M.T. Hoover. 1998. Performance of an at-grade septic system preceded by a pressure-dosed sand filter on a wet, clayey slate belt soil. Pgs. 326-335. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Adams, A., M.T. Hoover, W.L. Arrington and L.E. Young. 1998. FACTSS: Failure analysis chart for troubleshooting septic systems. Pgs. 27-36. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Loomis, G., C. Bishop, M.T. Hoover, B. Lesiker and D. Sievers. 1998. Partnership strategies for establishing on-site wastewater training centers. Pgs. 113-118. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
- Weymann, D.F., A. Amoozegar and M.T. Hoover. 1998. Performance of an on-site wastewater disposal system in a slowly permeable soil. Pgs. 134-145. In: On-Site Wastewater Treatment: Proceedings of the Eighth National Symposium on Individual and Small Community Sewage Systems, Ed: D.M. Sievers. American Society of Agricultural Engineers, St. Joseph, MI
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Progress 01/01/97 to 12/31/97
Outputs
Suitable land with appropriate soils is not currently available at the Tidewater Research Station to address the effect of depth and duration of saturation on wastewater treatment from on-site systems. Data collection has been completed for a double-blind replicated field experiment to determine the effect of bacterial/enzymatic additives on septic tank performance. The experiment used four treatments (three additives and a control) applied to 48 experimental units (48 full-scale septic tanks) using a randomized complete block design. Statistical analysis of the data is on-going at this time.
Impacts
(N/A)
Publications
- LINDBO, D.L. and HOOVER, M.T. 1997. On-site wastewater management. In Nutrients in the Neuse River: Working towards solutions conference proceedings. p. 16-17. North Carolina Cooperative Extension Service, North Carolina State University, Raleigh, NC.
- HOOVER, M.T. and HAMPTON, N. 1997. NC State University research effort leads to approval of new septic system. On-Line News. , Sept. 9, 1997. North Carolina Cooperative Extension Service, North Carolina State University, Raleigh, NC. .
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Progress 01/01/96 to 12/30/96
Outputs
Suitable land with appropriate soils is not currently available at the TidewaterResearch Station to address the effect of depth and duration of saturation on wastewater treatment from on-site systems. The effect of bacterial/enzymatic additives on septic tank performance is being evaluated in a double-blind replicated field experiment using four treatments (including a placebo control) and twelve replications in 48 full scale septic tanks located in two mobile home parks.
Impacts
(N/A)
Publications
- HOOVER, M.T., HINSON, T. H., and EVANS, R.O. 1996. Sand lined trench septic systems on wet clayey soils. In Solutions: A technical conference on water quality. p. 92-95. North Carolina Cooperative Extension Service, North Carolina State Univ RENKOW, M., and HOOVER, M.T. 1996. Costs of on-site management options (COSMO): A user's guide. In Proceedings of 1996 National On-Site Wastewater Recycling Association (NOWRA) Annual Meeting, 12 p.
- NOWRA, Chicago, Illinois.
- PENNINGER, P., and HOOVER, M.T. 1995. Performance of an at-grade septic system in the slate belt soil system. Soil Science Society of North Carolina Proceedings. Volume 38, p. 101-111.
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Progress 01/01/95 to 12/30/95
Outputs
A graduate student has been identified to work on objective two. This student will begin his efforts in January 1996. Appropriate land must be allocated by the Tidewater Research Station and supplementary funding must be identified before work can begin on objective one. A funding proposal is being submitted to potential funding agencies. The allocation of land is not assured since the research design will cause substantial permanent land changes (such as ditches, buried tanks and buried pipes) that will influence future use for agricultural production.
Impacts
(N/A)
Publications
- NO PUBLICATIONS REPORTED THIS PERIOD.
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