Stormwater Control Measures Research Articles

A geospatial analysis of land use and stormwater management on fecal coliform contamination in North Carolina streams

Although non-point source (NPS) pathogen pollution is a leading cause of stream impairment in the United States, the sources of NPS pollution are often difficult to ascertain. While previous studies have employed land use regression methods to develop a greater understanding of the sources and dynamics of microbial NPS pollution, little work has explicitly considered the effects of local, state, and federal stormwater management policies on water quality across multiple watersheds or at larger spatial scales. How do land use and stormwater management efforts collectively influence fecal coliform (FC) levels at a regional or multiple-watershed scale? We construct a unique spatial regression model of stream FC pollution (n=327 monitoring stations) throughout the state of North Carolina (USA), incorporating both land cover and urban development variables. We then use a subset of our data (nbmp=80 monitoring stations) to incorporate local stormwater control measures and stormwater management policies. Results demonstrate that the inclusion of policy and management variables improves the explanatory capacity for FC levels (R2=0.4412 versus R2=0.5323). Locally, this model can be used to better target stream restoration and water quality mitigation actions and investments, as well as help to predict FC levels at unmonitored locations throughout North Carolina's stream network. More generally, the novel structure of this model can also help examine the large-scale effects of stormwater regulations on surface water pathogen levels, helping researchers and planners better predict water quality in the absence of extensive monitoring station data.

Understanding the Relationship between Stormwater Control Measures and Ecosystem Services in an Urban Watershed

AbstractThe dilemma of managing the trade-off between immediate human needs and maintaining the ability of the Earth to provide ecosystem services is considered to be one of the greatest challenges...

Evapotranspiration in Rain Gardens Using Weighing Lysimeters

Quantification of evapotranspiration (ET) and infiltration from vegetated stormwater control measures (SCMs), such as rain gardens, is necessary to properly assess their volume reduction potential. Weighing lysimeters at Villanova University mimic three rain garden designs and measure water budget parameters to determine how design elements impact ET. The designs compare two soil media with the same unconstricted drainage systems: a sandy loam and sand and two drainage systems with the same media (sand): an unconstricted valve (UV) outflow and internal water storage (IWS) outflow. A custom system distributed water over the lysimeters to mimic the runoff typically delivered to a rain garden during natural storm events. Runoff simulation trials were performed in summer and fall and compared to direct rainfall to the lysimeters during those seasons. Evapotranspiration rates were unaffected in the sandy loam lysimeter and increased in the sand lysimeters by the simulated rainfall in each system. Average ET over the entire study period was 2.9, 2.7, and 4.3 mm/d for the sandy loam, sand, and sand internal water storage, respectively. Evapotranspiration made up 47, 43, and 70% of the water budget for the sandy loam, sand, and sand IWS systems, respectively. The native soil (sandy loam) did not negatively affect the rate of ET. The IWS drainage system enhanced ET over the unconstricted valve drainage system. In an effort to promote inclusion of ET into rain garden design, seasonal and monthly ET rates are provided as baseline values. The ASCE Penman-Monteith ET and Hargreaves ET equations adequately represent the unconstricted valve lysimeter systems and underrepresent the IWS lysimeter system.

The Performance Analysis of Two Relatively Small Capacity Urban Retrofit Stormwater Controls

This paper details field investigations that were conducted on the performance of small capacity urban retrofit stormwater control measures. The objective of t…

Evaluating Maintenance Requirements and Performance of Emerging Stormwater Control Measures at Dedicated Testing Center

Evaluating Maintenance Requirements and Performance of Emerging Stormwater Control Measures at Dedicated Testing Center

Bioretention storm water control measures decrease the toxicity of copper roof runoff.

The present study evaluated the ability of 2 different bioretention storm water control measures (SCMs), planter boxes and swales, to decrease the toxicity of sheet copper (Cu) roofing runoff to Daphnia magna. The present study quantified changes in storm water chemistry as it passed through the bioretention systems and utilized the biotic ligand model (BLM) to assess whether the observed D. magna toxicity could be predicted by variations found in water chemistry. Laboratory toxicity tests were performed using select storm samples with D. magna cultured under low ionic strength conditions that were appropriate for the low ionic strength of the storm water samples being tested. The SCMs decreased toxicity of Cu roof runoff in both the BLM results and the storm water bioassays. Water exiting the SCMs was substantially higher than influent runoff in pH, ions, alkalinity, and dissolved organic carbon and substantially lower in total and dissolved Cu. Daphnids experienced complete mortality in untreated runoff from the Cu roof (the SCM influent); however, for planter and swale effluents, survival averaged 86% and 95%, respectively. The present study demonstrated that conventional bioretention practices, including planter boxes and swales, are capable of decreasing the risk of adverse effects from sheet Cu roof runoff to receiving systems, even before considering dilution of effluents in those receiving systems and associated further reductions in copper bioavailability. Environ Toxicol Chem 2017;36:1680-1688. © 2016 SETAC.

Infiltration capacity of roadside filter strips with non-uniform overland flow

The side slope to a roadside swale (drainage ditch) constitutes a filter strip that has potential for infiltration of road runoff, thereby serving as a stormwater quantity and quality control mechanism. A total of thirty-two tests were performed during three seasons in four different highways located in the Minneapolis-St. Paul metropolitan area, MN to analyze the infiltration performance of roadside filter strips and the effect of fractional coverage of water on infiltration. Three different application rates were used in the experiments. All the tests showed that water flow on the lateral slope of a roadside swale is concentrated in fingers, instead of sheet flow, at the typical road runoff intensities for which infiltration practices are utilized to improve surface water quality. A linear relationship between flux of water from the road and fraction of wetted surface was observed, for the intensities tested.The average percentage infiltration of the medium road runoff rate (1.55×10−4m2/s, without direct rainfall) experiments performed in fall was 85% and in spring 70%. For the high road runoff rate (3.1×10−4m2/s, without direct rainfall) tests the average amount of water infiltrated was 47% and for the low road runoff rate (7.76×10−5m2/s, without direct rainfall) tests it was 69%, both set of tests performed in spring and summer. The saturated hydraulic conductivity of swale soil was high, relative to the values typical of laboratory permeameter measurements for these types of soils. This is believed to be due to the macropores generated by vegetation roots, activity of macrofauna (e.g. earthworms), and construction/maintenance procedures. The trend was to have more infiltration when the saturated hydraulic conductivity was higher and for a greater side slope length, as expected. The vegetation, type of soil and length of the side slope are important to consider for constructing and maintaining roadside swales that will be efficient as stormwater control measures. These measurements indicate that the filter strip portion of a roadside swale typically infiltrates a substantial fraction of road runoff. However, the measurements do not incorporate the influence of direct rainfall upon the infiltration into filter strips.

Characterizing the Effects of Stormwater Mitigation on Nutrient Export and Stream Concentrations.

Urbanization increases nutrient loading and lowers residence times for processing of reactive solutes, including nitrate, total dissolved nitrogen, orthophosphate, and dissolved organic carbon), which leads to increased stream concentrations and mass export. Stormwater control measures mitigate the impacts of urbanization, and have the potential to improve stream water quality, however the net effect instream is not well understood. We monitored two urban and two suburban watersheds in Charlotte, NC to determine if mitigation controlled the fraction of total mass export during storm, if development classification as either urban or suburban (defined by the age, density and distribution of urban development) controlled storm nutrient and carbon dynamics, and if stormwater control measures were able to change stream water chemistry. While average concentrations during stormflow were generally greater than baseflow, indicating that storms are important times of solute export, the fraction of storm-derived export was unrelated to mitigation by stormwater control measures. Development classification was generally not an important control on export of N and dissolved organic carbon. However, event mean concentrations of orthophosphate were higher at the suburban sites, possibly from greater fertilizer application. Stormwater control measures influenced instream water chemistry at only one site, which also had the greatest mitigated area, but differences between stormwater control measure outflow and stream water suggest the potential for water quality improvements. Together, results suggest stormwater control measures have the potential to decrease solute concentrations from urban runoff, but the type, location, and extent of urban development in the watershed may influence the magnitude of this effect.

Hydrologic response of engineered media in living roofs and bioretention to large rainfalls: experiments and modeling

AbstractThe hydrologic response of engineered media plays an important role in determining a stormwater control measure's ability to reduce runoff volume, flow rate, timing, and pollutant loads. Five engineered media, typical of living roof and bioretention stormwater control measures, were investigated in laboratory column experiments for their hydrologic responses to steady, large inflow rates. The inflow, medium water content response, and outflow were all measured. The water flow mechanism (uniform flow vs. preferential flow) was investigated by analyzing medium water content response in terms of timing, magnitude, and sequence with depth. Modeling the hydrologic process was conducted in the HYDRUS‐1D software, applying the Richards equation for uniform flow modeling, and a mobile–immobile model for preferential flow modeling. Uniform flow existed in most cases, including all initially dry living roof media with bimodal pore size distributions and one bioretention medium with unimodal pore size distribution. The Richards equation can predict the outflow hydrograph reasonably well for uniform flow conditions when medium hydraulic properties are adequately represented by appropriate functions. Preferential flow was found in two media with bimodal pore size distributions. The occurrence of preferential flow is more likely due to the interaction between the bimodal pore structure and the initial water content rather than the large inflow rate.

Social construction of stormwater control measures in Melbourne and Copenhagen: A discourse analysis of technological change, embedded meanings and potential mainstreaming

Urban stormwater systems in cities around the world are challenged by urbanization and climate change, and a range of Stormwater Control Measures (SCMs) are being implemented as solutions to these challenges. We developed a conceptual framework of technological stabilization based on Social Construction of Technology (SCOT) and Transition Science, and conducted 16 in-depth actor interviews as a basis for mapping the historical development of in the two cities. The SCMs applied in Melbourne and Copenhagen are similar, but using a new framework for technological stabilization we identify differences in their application due to different physical, organizational and cultural contexts in the two cities, drought being the main driver during the past decade in Melbourne (1997–2010) and pluvial flooding in Copenhagen (2007-). In Melbourne there is currently a strong integrated understanding of SCMs: after decades of “new technology” development, “testing” and “opportunity” seeking a large degree of “agreement” about stormwater management as a mainstreamed professional practice has arisen. In Copenhagen there are currently multiple conflicting understandings of SCMs and signs of an emerging integrated understanding that offers “opportunities” for further development and implementation. It is clear from Melbourne's history that: successful full scale demonstration projects supported and developed by a wide range of actors helps building a common vision for SCM technologies, supportive policies across several governmental levels provide incentives for implementation, and inclusive actions in the closure process provides a sense of ownership for SCM technologies across disciplines.

Evaluating the spatial distribution of pollutants and associated maintenance requirements in an 11 year-old bioretention cell in urban Charlotte, NC

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.

Phosphorus Retention in Stormwater Control Structures across Streamflow in Urban and Suburban Watersheds

Recent studies have shown that stormwater control measures (SCMs) are less effective at retaining phosphorus (P) than nitrogen. We compared P retention between two urban/suburban SCMs and their adjacent free-flowing stream reaches at the Baltimore Long-Term Ecological Study (LTER) site, and examined changes in P retention in SCMs across flow conditions. Results show that, when compared with free-flowing stream reaches, the SCMs had significantly lower dissolved oxygen (%DO) and higher P concentrations, as well as lower mean areal retention rates and retention efficiencies of particulate P (PP). In all the SCMs, concentrations of total dissolved phosphorus (TDP) consistently exhibited inverse correlations with %DO that was lower during summer base flows. Particulate phosphorus (PP) concentrations peaked during spring high flow period in both streams and in-line pond/SCMs, but they were also higher during summer base flows in suburban/urban SCMs. Meanwhile, PP areal retention rates and retention efficiencies of the SCMs changed from positive (indicating retention) during high flows to negative (indicating release) during low flows, while such changes across flow were not observed in free-flowing stream reaches. We attribute the changing roles of SCMs from a PP sink to a PP source to changes in SCM hydrologic mass balances, physical sedimentation and biogeochemical mobilization across flows. This study demonstrates that in suburban/urban SCMs, P retained during high flow events can be released during low flows. Cultivation of macrophytes and/or frequent sediment dredging may provide potential solutions to retaining both P and nitrogen in urban SCMs.

Characterizing Clinoptilolite Zeolite and Hydroaluminosilicate Aggregates for Ammonium Removal from Stormwater Runoff

AbstractAmmonium is a nitrogen species that can directly enter a stormwater control measure (SCM) or be produced from degradation of organic nitrogen available in stormwater runoff. Clinoptilolite zeolite (ZT) and a hydrous aluminosilicate (CA) were investigated for ammonium removal use in filtration-based SCMs. Sorption capacity, kinetics, and strength of attachment were completed in batch settings. For the four different background electrolytes tested at neutral pH, ZT showed the highest uptake, particularly at 0.03 M NaCl, followed by 0.01 M CaCl2. The lowest uptake was found to occur for K+ electrolytes. Kinetics of ammonium uptake was also found to be more rapid for ZT (i.e., 30 min for ZT and 240 min for CA), and increase in concentrations of Ca2+ and K+ slowed the sorption process from 30 to 240 min. Extraction studies indicated high extractability of ammonium in ZT, while CA showed slightly smaller extractable ammonium; the results suggest that ammonium removed by CA is less exchangeable and possi...

Hydrologic response to stormwater control measures in urban watersheds

Stormwater control measures (SCMs) are designed to mitigate deleterious effects of urbanization on river networks, but our ability to predict the cumulative effect of multiple SCMs at watershed scales is limited. The most widely used metric to quantify impacts of urban development, total imperviousness (TI), does not contain information about the extent of stormwater control. We analyzed the discharge records of 16 urban watersheds in Charlotte, NC spanning a range of TI (4.1–54%) and area mitigated with SCMs (1.3–89%). We then tested multiple watershed metrics that quantify the degree of urban impact and SCM mitigation to determine which best predicted hydrologic response across sites. At the event time scale, linear models showed TI to be the best predictor of both peak unit discharge and rainfall-runoff ratios across a range of storm sizes. TI was also a strong driver of both a watershed’s capacity to buffer small (e.g., 1–10mm) rain events, and the relationship between peak discharge and precipitation once that buffering capacity is exceeded. Metrics containing information about SCMs did not appear as primary predictors of event hydrologic response, suggesting that the level of SCM mitigation in many urban watersheds is insufficient to influence hydrologic response. Over annual timescales, impervious surfaces unmitigated by SCMs and tree coverage were best correlated with streamflow flashiness and water yield, respectively. The shift in controls from the event scale to the annual scale has important implications for water resource management, suggesting that overall limitation of watershed imperviousness rather than partial mitigation by SCMs may be necessary to alleviate the hydrologic impacts of urbanization.

Water Level Loggers as a Low-Cost Tool for Monitoring of Stormwater Control Measures

Stormwater control measures (SCMs) are a key component of watershed health in urbanized areas. SCMs are used to increase infiltration and reduce discharge to streams or storm sewer systems during rain events. Monitoring is important for the evaluation of design and causes of failure in SCMs. However, the expense of monitoring means it is not always included in stormwater control planning. This study shows how low-cost water level loggers can be used to answer certain questions about SCM performance. Five case studies are presented that use water level loggers to evaluate the overflow of basins, compare a traditional stormpipe trench with an infiltration trench, monitor timing of blue roof storage, show the effects of retrofitting a basin, and provide long term performance data. Water level loggers can be used to answer questions about the timing and location of stormwater overflows, which helps to evaluate the effectiveness of SCMs. More expensive monitoring and modeling can be used as a follow up if needed to more thoroughly assess a site. Nonetheless, low-cost monitoring can be a first step in identifying sites that need improvement or additional monitoring.

Nutrient Sequestration by Vegetation in Bioretention Cells Receiving High Nutrient Loads

AbstractBioretention plant selection for nutrient removal (and even basic plant survival) is an understudied and not-well-understood component of this stormwater control measure. Twelve bioretention cells were constructed to evaluate 16 plants growing in three different media for their ability to remove nutrient pollution from urban stormwater runoff with high nutrient loads. Plants evaluated were pairs of natives and cultivars and included trees (Magnolia and Betula), shrubs (Viburnum and Itea), herbaceous perennial flowers (Helianthus and Eupatorium), a rush (Juncus), and an ornamental grass (Panicum). Eleven of the 16 species (B. nigra; B. Dura-Heat; M. virginiana; M. Sweet Thing; I. virginica; I. Henry’s Garnet; J. effusus; P. Shenandoah; H. angustifolius; H. First Light; and E. Gateway) performed well (grew and were aesthetically acceptable) in the bioretention cells and can be recommended as bioretention plants. Species and cultivar impacted the levels of remediation of the high N and P loads applie...

Characterizing Runoff from Roads: Particle Size Distributions, Nutrients, and Gross Solids

AbstractParticulate matter, nutrients, and gross solids from roads contribute nonpoint-source pollution to waterways. To inform road runoff management, a field monitoring study was undertaken at eight road sites across North Carolina. Particle size distributions (PSD) of edge-of-pavement runoff samples were analyzed to understand the granulometry of the particulate matter. Knowledge of PSDs is critical when attempting to understand sediment fate and transport through stormwater control measures (SCMs), especially when the primary removal mechanism is particle settling. For 43 road runoff events, median particle size varied from 31 to 144 μm. The median PSD from hot mix asphalt (HMA) was 2.6% clay, 44.8% silt, and 52.6% sand. PSD was not correlated to roadway classification or ecoregion; however, PSD was significantly correlated to the presence of a permeable friction course (PFC) overlay, which is a layer of porous asphalt placed over traditional HMA. The median d90 for PFC (131 μm) was significantly smal...

Modeling Sediment Reduction in Grass Swales and Vegetated Filter Strips Using Particle Settling Theory

AbstractTwo of the most common and simple stormwater control measures are swales and filter strips. However, an overly simplistic one-size-fits-all design approach typically is used for these practices. To provide more flexibility in design, a coupled hydraulics and particle-settling model was created to predict swale and filter strip total suspended solids (TSS) reduction as a function of catchment area, longitudinal slope, side slope, cross section type (triangular swale, trapezoidal swale, or filter strip), and length. The hydraulics and hydrology models were based on Manning’s equation and the rational method, respectively, with the underlying requirement that the water quality design storm does not exceed the height of the grass. The particle-settling model was underpinned by the Aberdeen equation. The model predicts that triangular swales produce the least and filter strips the most TSS removal because of increased hydraulic retention time; trapezoidal swales had on average 10% greater TSS removal t...

Efficiency of stormwater control measures for combined sewer retrofitting under varying rain conditions: Quantifying the Three Points Approach (3PA)

We present a method to assess and communicate the efficiency of stormwater control measures for retrofitting existing urban areas. The tool extends the Three Points Approach to quantitatively distinguish three rainfall domains: (A) rainwater resource utilisation, (B) urban stormwater drainage pipe design, and (C) pluvial flood mitigation. Methods for calculating efficiencies are defined recognizing that rainfall is both a valuable resource and a potential problem. Efficiencies are quantified in relation to rainfall volume, supplied potable water volume and volume of wastewater treated. A case study from Denmark is used to illustrate how the efficiency varies between the rainfall domains. The method provides a means for communicating some important quantitative aspects of stormwater control measures among engineers, planners and decision makers working with management of water resources, stormwater drainage and flood risks.

Development of a hybrid expert system-multi criteria analysis on erosion and sediment control in construction industry

Construction activities combined with heavy rainfall can results in severe soil loss which eventually will be deposited into the adjacent water bodies via stormwater. The Best Management Practices (BMPs) adopted to minimise the erosion and sedimentation during construction activities are usually determined by standard guidelines and expert engineers. However, when the expertise and data are limited, knowledge-based systems have been proved as an effective alternative in making decision. A new algorithm of hybrid knowledge-based expert system and Multi-Criteria Analysis (MCA) was developed to minimise erosion and sedimentation due to stormwater in Malaysian construction sites. In this Eco-Friendly Erosion and Sediment Control (ECO-ESC) system, decision tables were developed based on the knowledge acquired from the domain experts specialised in erosion and sedimentation control and guidelines. The MCA was used to identify the best stormwater control measures based on the specific criteria and criterion's weight. The ECO-ESC was validated in three stages: preliminary by the experts, field and statistical validations. Results of comparison have shown high correlation for recommended BMPs, sediment yield, and the water quality monitoring and proved that the ECO-ESC performs as good as the human expert in solving different problems related to the erosion and sediment control.