Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence
Onsite wastewater treatment systems (OWTSs) are commonly used in eastern North Carolina. A vadose zone or vertical separation distance (VSD) between the OWTS drainfield trenches and groundwater is required for effective aerobic wastewater treatment. Extreme weather events, including hurricanes, can...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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IWA Publishing
2021-08-01
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| Series: | Journal of Water and Climate Change |
| Subjects: | |
| Online Access: | http://jwcc.iwaponline.com/content/12/5/2136 |
| _version_ | 1818695383709122560 |
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| author | Charles Humphrey Jr. Danielle Dillane Guy Iverson Michael O'Driscoll |
| author_facet | Charles Humphrey Jr. Danielle Dillane Guy Iverson Michael O'Driscoll |
| author_sort | Charles Humphrey Jr. |
| collection | DOAJ |
| description | Onsite wastewater treatment systems (OWTSs) are commonly used in eastern North Carolina. A vadose zone or vertical separation distance (VSD) between the OWTS drainfield trenches and groundwater is required for effective aerobic wastewater treatment. Extreme weather events, including hurricanes, can deliver significant rainfall that influences groundwater levels and reduces the VSD, thus also influencing the treatment of wastewater by the OWTS. Few studies have quantified the effects of storms on the VSD. Groundwater levels at three sites with the OWTS were monitored before, during, and after Hurricane Florence. Groundwater rose over 1.5 m within 9 h at the sites in response to rain from the hurricane but took more than 3.5 weeks to return to prestorm levels. Groundwater inundated the drainfield trenches for several days at two sites leading to direct discharge of wastewater to groundwater. The hydraulic gradient and the groundwater velocity increased during the storm and the groundwater flow direction shifted, leading to greater dispersion of wastewater impacted groundwater. The wastewater treatment efficiency of the soil-based OWTS in coastal areas may lessen over time because of rising water tables and reduced VSD. Individual pretreatment OWTSs, elevated drainfields, or centralized sewage treatment may be required in regions with shrinking VSDs. HIGHLIGHTS
Groundwater levels directly beneath three onsite wastewater systems were monitored during Hurricane Florence.;
A vertical separation distance decreased by more than 1.5 m at each site in response to rain from the hurricane.;
Direct discharge of wastewater to groundwater occurred at two of three sites.;
The onsite wastewater treatment efficiency may diminish in coastal areas in response to more frequent intense storms.; |
| first_indexed | 2024-12-17T13:44:36Z |
| format | Article |
| id | doaj.art-430c997e7e974bcbae6fca31ed157065 |
| institution | Directory Open Access Journal |
| issn | 2040-2244 2408-9354 |
| language | English |
| last_indexed | 2024-12-17T13:44:36Z |
| publishDate | 2021-08-01 |
| publisher | IWA Publishing |
| record_format | Article |
| series | Journal of Water and Climate Change |
| spelling | doaj.art-430c997e7e974bcbae6fca31ed1570652022-12-21T21:46:11ZengIWA PublishingJournal of Water and Climate Change2040-22442408-93542021-08-011252136214610.2166/wcc.2021.303303Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane FlorenceCharles Humphrey Jr.0Danielle Dillane1Guy Iverson2Michael O'Driscoll3 Environmental Health Sciences Program, Department of Health Education and Promotion, East Carolina University, Greenville, NC 27858, USA Doctorate of Public Health Program, Department of Public Health, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA Environmental Health Sciences Program, Department of Health Education and Promotion, East Carolina University, Greenville, NC 27858, USA Department of Coastal Studies, East Carolina University, Greenville, NC 27858, USA Onsite wastewater treatment systems (OWTSs) are commonly used in eastern North Carolina. A vadose zone or vertical separation distance (VSD) between the OWTS drainfield trenches and groundwater is required for effective aerobic wastewater treatment. Extreme weather events, including hurricanes, can deliver significant rainfall that influences groundwater levels and reduces the VSD, thus also influencing the treatment of wastewater by the OWTS. Few studies have quantified the effects of storms on the VSD. Groundwater levels at three sites with the OWTS were monitored before, during, and after Hurricane Florence. Groundwater rose over 1.5 m within 9 h at the sites in response to rain from the hurricane but took more than 3.5 weeks to return to prestorm levels. Groundwater inundated the drainfield trenches for several days at two sites leading to direct discharge of wastewater to groundwater. The hydraulic gradient and the groundwater velocity increased during the storm and the groundwater flow direction shifted, leading to greater dispersion of wastewater impacted groundwater. The wastewater treatment efficiency of the soil-based OWTS in coastal areas may lessen over time because of rising water tables and reduced VSD. Individual pretreatment OWTSs, elevated drainfields, or centralized sewage treatment may be required in regions with shrinking VSDs. HIGHLIGHTS Groundwater levels directly beneath three onsite wastewater systems were monitored during Hurricane Florence.; A vertical separation distance decreased by more than 1.5 m at each site in response to rain from the hurricane.; Direct discharge of wastewater to groundwater occurred at two of three sites.; The onsite wastewater treatment efficiency may diminish in coastal areas in response to more frequent intense storms.;http://jwcc.iwaponline.com/content/12/5/2136climate changegroundwaterhurricaneonsite wastewatervadose zone |
| spellingShingle | Charles Humphrey Jr. Danielle Dillane Guy Iverson Michael O'Driscoll Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence Journal of Water and Climate Change climate change groundwater hurricane onsite wastewater vadose zone |
| title | Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence |
| title_full | Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence |
| title_fullStr | Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence |
| title_full_unstemmed | Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence |
| title_short | Water table dynamics beneath onsite wastewater systems in eastern North Carolina in response to Hurricane Florence |
| title_sort | water table dynamics beneath onsite wastewater systems in eastern north carolina in response to hurricane florence |
| topic | climate change groundwater hurricane onsite wastewater vadose zone |
| url | http://jwcc.iwaponline.com/content/12/5/2136 |
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