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Jeffrey P. Johnson
Extension Associate, Dept. of Biological and Agricultural Engineering, North Carolina State Univ., Campus Box 7625, Raleigh, NC 27695 (corresponding author). ORCID:

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Journal article
Published: 01 November 2020 in Journal of Sustainable Water in the Built Environment
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Increasing imperviousness has driven regulation and design philosophies to offset consequent increases in runoff volumes and peak flows. Previous research has shown bioretention to reduce runoff volumes and peak flows. Since most research has focused on newly constructed systems, the long-term performance of bioretention has been questioned. Because bioretention is a biologically based practice, changes over time could impact hydrologic performance. This research examined and compared the hydrologic mitigation performance of three bioretention cells (BRCs) in central North Carolina with postconstruction ages ranging from 8 to 17 years old. Observed runoff volumes were significantly reduced at each of the three cells by 90%, 81%, and 64%. The volume discharge ratio for each cell was at or below low impact development (LID) target thresholds (0.33) for 63%, 67%, and 48% of observed storm events. Similar to volume reduction, all three BRCs significantly reduced peak flows. Peak discharge ratios at each site were less than the LID target threshold (0.33) for over 75% of observed storm events, and the interquartile range of peak discharge ratios was less than the LID target threshold for all observed storm events 50 mm). As the frequency and magnitude of larger events increases, guidance recommending additional surface storage should be considered. When compared to the hydrologic performance of “young” BRCs (less than 3 years old), “old” BRCs (at least 3 years old) perform at least as well with respect to peak flow mitigation while appearing to reduce runoff volumes better than newly constructed BRCs. That the three BRCs presented herein ranged from 8 to 17 years old during their respective monitoring periods while significantly reducing peak flows and runoff volumes (while meeting LID target thresholds) supports the prediction of long-term hydrologic mitigation of bioretention.

ACS Style

Jeffrey P. Johnson; William F. Hunt. Field Assessment of the Hydrologic Mitigation Performance of Three Aging Bioretention Cells. Journal of Sustainable Water in the Built Environment 2020, 6, 04020017 .

AMA Style

Jeffrey P. Johnson, William F. Hunt. Field Assessment of the Hydrologic Mitigation Performance of Three Aging Bioretention Cells. Journal of Sustainable Water in the Built Environment. 2020; 6 (4):04020017.

Chicago/Turabian Style

Jeffrey P. Johnson; William F. Hunt. 2020. "Field Assessment of the Hydrologic Mitigation Performance of Three Aging Bioretention Cells." Journal of Sustainable Water in the Built Environment 6, no. 4: 04020017.

Journal article
Published: 30 May 2020 in Water
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Stream restoration for mitigation purposes has grown rapidly since the 1980s. As the science advances, some organizations (Chesapeake Bay Program, North Carolina Department of Environmental Quality) have approved or are considering providing nutrient credits for stream restoration projects. Nutrient treatment on floodplains during overbank events is one of the least understood processes that have been considered as part of the Chesapeake Bay Program’s Stream Restoration Nutrient Crediting program. This study analyzed ten years of streamflow and water quality data from five stations in the Piedmont of North Carolina to evaluate proposed procedures for estimating nitrogen removal on the floodplain during overbank flow events. The volume of floodplain flow, the volume of floodplain flow potentially treated, and the nitrogen load retained on the floodplain were calculated for each overbank event, and a sensitivity analysis was completed. On average, 9% to 15% of the total annual streamflow volume accessed the floodplain. The percentage of the average annual volume of streamflow potentially treated ranged from 1.0% to 5.1%. Annually, this equates to 0.2% to 1.0% of the total N load retained/removed on the floodplain following restoration. The relatively low nitrogen retention/removal rates were due to a majority of floodplain flow occurring during a few large events each year that exceeded the treatment capacity of the floodplain. On an annual basis, 90% of total floodplain flow occurred during half of all overbank events and 50% of total floodplain flow occurred during two to three events each year. Findings suggest that evaluating only overbank events may lead to undervaluing stream restoration because treatment is limited by hydrologic controls that restrict floodplain retention time. Treatment is further governed by floodplain and channel size.

ACS Style

Barbara A. Doll; J. Jack Kurki-Fox; Jonathan L. Page; Natalie G. Nelson; Jeffrey P. Johnson. Flood Flow Frequency Analysis to Estimate Potential Floodplain Nitrogen Treatment during Overbank Flow Events in Urban Stream Restoration Projects. Water 2020, 12, 1 .

AMA Style

Barbara A. Doll, J. Jack Kurki-Fox, Jonathan L. Page, Natalie G. Nelson, Jeffrey P. Johnson. Flood Flow Frequency Analysis to Estimate Potential Floodplain Nitrogen Treatment during Overbank Flow Events in Urban Stream Restoration Projects. Water. 2020; 12 (6):1.

Chicago/Turabian Style

Barbara A. Doll; J. Jack Kurki-Fox; Jonathan L. Page; Natalie G. Nelson; Jeffrey P. Johnson. 2020. "Flood Flow Frequency Analysis to Estimate Potential Floodplain Nitrogen Treatment during Overbank Flow Events in Urban Stream Restoration Projects." Water 12, no. 6: 1.

Journal article
Published: 01 February 2020 in Journal of Sustainable Water in the Built Environment
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Stormwater runoff from urban development causes undesired impacts to surface waters, including discharge of pollutants, stream erosion, and loss of in-stream habitat. Stormwater control measures (SCMs), such as ponds, wetlands, bioretention cells, and permeable pavements, are employed to ameliorate these impacts. A treatment train SCM was constructed and monitored in the parking lot at Old Woman Creek National Estuarine Research Reserve in Huron, Ohio. Native soils beneath this parking lot were heavy clay with measured average infiltration rates of 0.046 mm/h. The treatment train consisted of permeable interlocking concrete pavement (PICP) parking stalls that provided pretreatment for an underground stormwater harvesting system. The treatment train was intensively monitored for 13 months to quantify the water balance. The average postconstruction drawdown rate was 0.064 mm/h from the scarified soil beneath the permeable pavement, suggesting that if soil compaction imparted during construction is broken up, preconstruction soil testing provides representative estimates of postconstruction infiltration performance for permeable pavement. While stormwater stored in the cistern was never harvested during the monitoring period, total runoff volume was reduced significantly by 27% through infiltration into the underlying soils. Peak outflow rates were significantly reduced by 93.8%±10%. This was primarily related to slow exfiltration from the scarified soil underlying the permeable pavement. Additional (minor) exfiltration occurred due to an unintentional leak in the cistern, creating storage for follow-on events. These results suggest that scarifying the subsoil beneath permeable pavement without an internal water storage zone can lead to a modest amount of storage for stormwater in the subgrade (perhaps 2.5–5 cm below the underdrain invert), which would provide otherwise unrealized opportunities for exfiltration during inter-event periods. This treatment train SCM appears promising for reducing runoff volume and peak flow rate, particularly if a dedicated, year-round water use could be provided to drain the cistern between wet-weather events.

ACS Style

Ryan J. Winston; Kristi Arend; Jay D. Dorsey; Jeffrey P. Johnson; William F. Hunt. Hydrologic Performance of a Permeable Pavement and Stormwater Harvesting Treatment Train Stormwater Control Measure. Journal of Sustainable Water in the Built Environment 2020, 6, 04019011 .

AMA Style

Ryan J. Winston, Kristi Arend, Jay D. Dorsey, Jeffrey P. Johnson, William F. Hunt. Hydrologic Performance of a Permeable Pavement and Stormwater Harvesting Treatment Train Stormwater Control Measure. Journal of Sustainable Water in the Built Environment. 2020; 6 (1):04019011.

Chicago/Turabian Style

Ryan J. Winston; Kristi Arend; Jay D. Dorsey; Jeffrey P. Johnson; William F. Hunt. 2020. "Hydrologic Performance of a Permeable Pavement and Stormwater Harvesting Treatment Train Stormwater Control Measure." Journal of Sustainable Water in the Built Environment 6, no. 1: 04019011.

Journal article
Published: 12 October 2019 in Journal of Environmental Management
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Regenerative stormwater conveyance (RSC) is a recently developed stormwater control measure that marries the concepts of bioretention and stream restoration. RSC mitigates stormwater runoff by converting surface flow to subsurface seepage using a series of pools and riffles built over a sand media bed. Subsurface seepage flows through media and exits the RSC beneath the outlet weir. Previous studies on RSC pollutant mitigation have focused on surface flow discharges from the RSC. To date, no known research has been conducted on the potential pollutant contributions of RSC seepage, despite the fact that this water also enters receiving waters. This research used Multi-Point Sampling coupled with in-situ ultraviolet–visual spectroscopy to measure nitrogen in seepage during simulated storm events (n = 9) at a field-scale RSC in Raleigh, North Carolina. Calibrations between light absorbance and concentrations were acceptable (Nash-Sutcliffe coefficient > 0.65) for nitrate and total ammoniacal nitrogen (TAN) and very good (Nash-Sutcliffe coefficient > 0.90) for total Kjehdahl nitrogen (TKN). Early storm simulations revealed some initial nutrient flushing from the substrate, which subsided by the third simulation. Overall, subsurface seepage nitrate, TAN, and TKN concentrations were lower by 29%, 57%, and 4% relative to storm inflow concentrations, respectively. Computed subsurface nitrogen concentrations demonstrated temporal variability, highlighting dynamic transport and biogeochemical transformations in saturated and unsaturated conditions. Nitrogen concentrations were lower in seepage than in surface flow; however, due to the high volume of runoff converted to seepage, nitrogen loads discharged in seepage can be larger than those of surface flow. Further research is needed to examine subsurface pollutant reductions under varying hydrologic and seasonal conditions.

ACS Style

Adrienne R. Cizek; Jeffrey P. Johnson; François Birgand; William F. Hunt; Richard A. McLaughlin. Insights from using in-situ ultraviolet–visible spectroscopy to assess nitrogen treatment and subsurface dynamics in a regenerative stormwater conveyance (RSC) system. Journal of Environmental Management 2019, 252, 109656 .

AMA Style

Adrienne R. Cizek, Jeffrey P. Johnson, François Birgand, William F. Hunt, Richard A. McLaughlin. Insights from using in-situ ultraviolet–visible spectroscopy to assess nitrogen treatment and subsurface dynamics in a regenerative stormwater conveyance (RSC) system. Journal of Environmental Management. 2019; 252 ():109656.

Chicago/Turabian Style

Adrienne R. Cizek; Jeffrey P. Johnson; François Birgand; William F. Hunt; Richard A. McLaughlin. 2019. "Insights from using in-situ ultraviolet–visible spectroscopy to assess nitrogen treatment and subsurface dynamics in a regenerative stormwater conveyance (RSC) system." Journal of Environmental Management 252, no. : 109656.

Journal article
Published: 02 April 2019 in Sustainability
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One of the most popular stormwater practices in (sub-)urban North Carolina is bioretention. While bioretention has been researched intensively to determine the most efficient designs, few long-term studies have attempted to assess the performance of older bioretention. However, previous research and design guidance for bioretention has predicted long-term water quality treatment. This study compared discharged concentrations and loads of nitrogen and phosphorus from a bioretention cell (1) post-construction and (2) following 17 years of treatment. A conventionally-drained bioretention cell with lateral underdrains in Chapel Hill, North Carolina, USA, was first monitored post-construction for 10-months from 2002–2003 and, again following continuous use, for 14 months from 2017–2018. Estimated mass load reductions during the initial monitoring period were 40% for total nitrogen (TN) and 65% for total phosphorus (TP). Mass load reductions were increased 17 years after construction, with reductions of 72% and 79% for TN and TP, respectively. Plant growth, death, and decay over the 17-year life of the bioretention cell are hypothesized to have contributed additional nitrogen assimilation and carbon to the fill media, serving as a catalyst for nitrogen treatment. Phosphorus removal remained relatively unchanged between the two monitoring periods. Filter media samples indicated the top 20 cm of filter media were nearing phosphorus saturation, but with 1.2 m of filter media, lower depths would most likely continue to provide treatment. If designed, built, and maintained correctly, bioretention appears to provide sustained treatment of stormwater runoff for nitrogen and phosphorus for nearly two decades, and likely longer.

ACS Style

Jeffrey P. Johnson; William F. Hunt. A Retrospective Comparison of Water Quality Treatment in a Bioretention Cell 16 Years Following Initial Analysis. Sustainability 2019, 11, 1945 .

AMA Style

Jeffrey P. Johnson, William F. Hunt. A Retrospective Comparison of Water Quality Treatment in a Bioretention Cell 16 Years Following Initial Analysis. Sustainability. 2019; 11 (7):1945.

Chicago/Turabian Style

Jeffrey P. Johnson; William F. Hunt. 2019. "A Retrospective Comparison of Water Quality Treatment in a Bioretention Cell 16 Years Following Initial Analysis." Sustainability 11, no. 7: 1945.

Journal article
Published: 01 December 2016 in Journal of Environmental Management
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Bioretention cells (BRCs) are an increasingly popular Stormwater Control Measure used to mitigate the hydrologic and water quality impacts of urbanization. Previous BRC research has demonstrated a strong capacity for pollutant removal; however, long-term sequestration of pollutants within soil media can elevate concentrations to levels fostering environmental and human health risks. Soil media samples were collected from an 11 year-old BRC in Charlotte, NC, and analyzed for the accumulation and spatial distribution of zinc, copper, and phosphorus. Pollutant distribution varied significantly with respect to depth and ordinate distance from the BRC inlet. Zinc concentrations (0.9-228.6 mg kg(-1) soil) exceeded environmental thresholds and phosphorus concentrations (5.1-173.3 mg kg(-1) soil) increased from initial levels by a factor of seven; however, notable accumulation was restricted to the BRC forebay. Maximum zinc and copper concentrations in soil media did not exceed 1% of mandatory cleanup levels and with regular maintenance of the forebay, the effective life of BRC media should exceed the life of the developments they treat.

ACS Style

Jeffrey P. Johnson; William F. Hunt. Evaluating the spatial distribution of pollutants and associated maintenance requirements in an 11 year-old bioretention cell in urban Charlotte, NC. Journal of Environmental Management 2016, 184, 363 -370.

AMA Style

Jeffrey P. Johnson, William F. Hunt. Evaluating the spatial distribution of pollutants and associated maintenance requirements in an 11 year-old bioretention cell in urban Charlotte, NC. Journal of Environmental Management. 2016; 184 ():363-370.

Chicago/Turabian Style

Jeffrey P. Johnson; William F. Hunt. 2016. "Evaluating the spatial distribution of pollutants and associated maintenance requirements in an 11 year-old bioretention cell in urban Charlotte, NC." Journal of Environmental Management 184, no. : 363-370.