Urban Stormwater BMPs and Stream Quality

 Last updated: 10/13/10

This list includes resources for understanding how urban stormwater best management practices (BMPs) and low impact design (LID) effect stream quality.

Online documents

United States EPA. 2000.  Low Impact Development (LID) A Literature Review. EPA Document # EPA-841-B-00-005.  Available at: http://www.lowimpactdevelopment.org/pubs/LID_litreview.pdf

The Low Impact Development Center, Inc. Publications list. Available at: http://www.lowimpactdevelopment.org/publications.htm

Environmental Services Division, Department of Environmental Resources, Prince George's County, Maryland. Revised 2007. Bioretention Manual. Available at: http://www.princegeorgescountymd.gov/der/esg/bioretention/bioretention.asp


Brown, Ted. 2010. Can volume-based stormwater criteria make a difference to receiving stream health? Water Resources Impact 12(2): 5-8.

Coffman, Larry S.  2000. Low-impact development design: a new paradigm for stormwater management mimicking and restoring the natural hydrologic regime: an alternative stormwater management technology. Environmental Protection Agency. National Conference on Tools for Urban Water Resources Management and Protection: proceedings. Cincinnati, EPA, July 2000, p. 158-67.

Damodaram, Chandana, Marcio H. Giacomoni, C. Prakash Khedun, Hillary Holmes, Andrea Ryan, William Saour, and Emily M. Zechman. 2010. Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management. Journal of the American Water Resources Association 46(5): 1-12.

Urbanization causes increased stormwater runoff volumes, leading to erosion, flooding, and the degradation of instream ecosystem health. Although Best Management Practices (BMPs) are used widely as a means for controlling flood runoff events, Low Impact Development (LID) options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID practices such as rainwater harvesting, green roofs, and permeable pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices in an existing hydrologic model to estimate the effects of LID choices on streamflow. The modeling approach has been applied to a watershed located on the campus of Texas A&M University in College Station, Texas, to predict the stormwater reductions resulting from retrofitting existing infrastructure with LID technologies. Results demonstrate that use of these LID practices yield significant stormwater control for small events and less control for flood events. A combined BMP-LID approach is tested for runoff control for both flood and frequent rainfall events.

Davis, AP, et al. 2009. Bioretention Technology: Overview of Current Practice and Future Needs. JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE, 135 (3): 109-117.

Abstract: Bioretention, or variations such as bioinfiltration and rain gardens, has become one of the most frequently used storm-water management tools in urbanized watersheds. Incorporating both filtration and infiltration, initial research into bioretention has shown that these facilities substantially reduce runoff volumes and peak flows. Low impact development, which has a goal of modifying postdevelopment hydrology to more closely mimic that of predevelopment, is a driver for the use of bioretention in many parts of the country. Research over the past decade has shown that bioretention effluent loads are low for suspended solids, nutrients, hydrocarbons, and heavy metals. Pollutant removal mechanisms include filtration, adsorption, and possibly biological treatment. Limited research suggests that bioretention can effectively manage other pollutants, such as pathogenic bacteria and thermal pollution, as well. Reductions in pollutant load result from the combination of concentration reduction and runoff volume attenuation, linking water quality and hydrologic performance. Nonetheless, many design questions persist for this practice, such as maximum pooling bowl depth, minimum fill media depth, fill media composition and configuration, underdrain configuration, pretreatment options, and vegetation selection. Moreover, the exact nature and impact of bioretention maintenance is still evolving, which will dictate long-term performance and life-cycle costs. Bioretention usage will grow as design guidance matures as a result of continued research and application.

Davis, AP, et al. 2006. Water quality improvement through bioretention media: Nitrogen and phosphorus removal. WATER ENVIRONMENT RESEARCH, 78 (3): 284-293.

Abstract: High nutrient inputs and eutrophication continue to be one of the highest priority water quality problems. Bioretention is a low-impact development technology that has been advocated for use in urban and other developed areas. This work provides an in-depth analysis on removal of nutrients from a synthetic stormwater runoff by bioretention. Results have indicated good removal of phosphorus (70 to 85%) and total Kjeldahl nitrogen (55 to 65%). Nitrate reduction was poor (< 20%) and, in several cases, nitrate production was noted. Variations in flowrate (intensity) and duration had a moderate affect on nutrient removal. Mass balances demonstrate the importance of water attenuation in the facility in reducing mass nutrient loads. Captured nitrogen can be converted to nitrate between storm events and subsequently washed from the system. Analysis on the fate of nutrients in bioretention suggests that accumulation of phosphorus and nitrogen may be controlled by carefully managing growing and harvesting of vegetation.

Davis, AP, et al. 2003. Water quality improvement through bioretention: Lead, copper, and zinc removal. WATER ENVIRONMENT RESEARCH, 75 (1): 73-82

Abstract: Intensive automobile use, weathering of building materials, and atmospheric deposition contribute lead, copper, zinc, and other heavy metals to urban and roadway runoff. Bioretention is a low-impact-development best management practice that has the potential to improve stormwater quality from developed areas. The practice represents a soil, sand, organic matter, and vegetation-based storage and infiltration facility used in parking lots and on individual lots to treat runoff. Investigations using pilot-plant laboratory bioretention systems and two existing bioretention facilities documented their effectiveness at removing low levels of lead, copper, and zinc from synthetic stormwater runoff. Removal rates of these metals (based on concentration and total mass) were excellent. reaching close to 100% for all metals under most conditions, with effluent copper and lead levels mostly less than 5 mug/L and zinc less than 25 mug/L. Somewhat less removal was noted for shallow bioretention depths. Runoff pH, duration, intensity, and pollutant concentrations were varied, and all had minimal effect on removal. The two field investigations generally supported the laboratory studies. Overall, excellent removal of dissolved heavy metals can be expected through bioretention infiltration. Although the accumulation of metals is a concern, buildup problems are not anticipated for more than 15 years because of the low metal concentrations expected in runoff.

Emerson, CH, Traver, RG. 2008. Multiyear and seasonal variation of infiltration from storm-water best management practices. JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING-ASCE, 134 (5): 598-605

Abstract: Reduction of storm-water volumes through infiltration is becoming a commonly applied practice in the effort to mitigate the negative hydrologic impacts commonly associated with land development. The hydrologic impacts generally include increases in both the volume and peak flow rate of runoff along with an associated decrease in groundwater recharge. Infiltration best management practices (BMPs) are the foundation of many low impact development and Green infrastructure practices. As the movement to volume reduction is a relatively recent concept, there remains a lack of detailed long-term monitoring data to support the implementation of storm-water infiltration BMPs. Two storm-water infiltration BMPs on the campus of Villanova University located in Southeastern Pennsylvania have been continuously monitored to determine the long-term and seasonal variation related to the engineered infiltration of storm-water runoff. The analysis of continuous monitoring data indicates that both BMPs show considerable seasonal variation but exhibit no evidence of a systematic decrease in performance to date. The seasonal variation of the BMPs is explained primarily by the temperature dependency of the viscosity of water.

Gilroy, KL, McCuen, RH. 2009. Spatio-temporal effects of low impact development practices. JOURNAL OF HYDROLOGY, 367 (3-4): 228-236.

Abstract: The increase in land development and urbanization experienced in the US and worldwide is causing environmental degradation. Traditional off-site stormwater management does not protect small streams. To mitigate the negative effects of land development, best management practices (BMPs) are being implemented into stormwater management policies for the purposes of controlling minor flooding and improving water quality. Unfortunately, the effectiveness of BMPs has not been extensively studied. The purpose of this research was to analyze the effects of both location and quantity of two types of BMPs: cisterns and bioretention pits. A spatio-temporal model of a microwatershed was developed to determine the effects of BMPs on single-family, townhome, and commercial lots. The effects of development and the BMPs on peak runoff rates and volumes were compared to pre-development conditions. The results show that cisterns alone are capable of controlling rooftop runoff for small storms. Both the spatial location and the volume of BMP storage on a microwatershed influences the effectiveness of BMPs. The volume of BMP storage is positively correlated to the percent reduction in the peak discharge rate and total runoff volume; however, location is a factor in the peak reduction and a maximum volume of effective storage for both hydrologic metrics does exist. These results provide guidelines for developing stormwater management policies that can potentially reduce pollution of first-order streams, lower the cost and maintenance requirements, enhance aesthetics, and increase safety.

Graham, P, et al. 2004. The role of water balance modelling in the transition to low impact development. WATER QUALITY RESEARCH JOURNAL OF CANADA, 39 (4): 331-342.

Abstract: Low impact development (LID) is increasingly being viewed by local governments and developers alike as a viable approach to stormwater management that can effectively protect aquatic habitat and water quality. LID relies on distributed runoff management measures that seek to control stormwater volume at the source by reducing imperviousness and retaining, infiltrating and reusing rainwater at the development site.
Early conventional stormwater management practices tended to focus on stormwater quantity and controlling a few extreme rainfall events, whereas the more frequent storms, which represent the majority of total runoff volume, carry most of the pollutants, and control the geomorphology of streams, were addressed in stormwater quality design practiced during the last decade. These frequent events are most effectively managed with a volume control approach, often described as stormwater source control or Low impact development (LID). Such an approach is described in this paper, demonstrating how water balance modelling can be an effective tool for evaluating and supporting implementation of LID options such as bioretention, pervious paving, numerous types of infiltration systems, rainwater reuse and green roofs. It also discusses recently developed water balance modelling software, including an Internet-based planning tool and a design optimization tool.

Holman-Dodds, Jennifer K., A. Allen Bradley, and Kenneth W. Potter. 2003. Evaluation of Hydrologic Benefits of Infiltration Based Urban Storm Water Management. Journal of the American Water Resources Association  39(1): 205-215.

ABSTRACT: As watersheds are urbanized, their surfaces are made less pervious and more channelized, which reduces infiltration and speeds up the removal of excess runoff. Traditional storm water management seeks to remove runoff as quickly as possible, gathering excess runoff in detention basins for peak reduction where necessary. In contrast, more recently developed low impact alternatives manage rainfall where it falls, through a combination of enhancing infiltration properties of pervious areas and rerouting impervious runoff across pervious areas to allow an opportunity for infiltration. In this paper, we investigate the potential for reducing the hydrologic impacts of urbanization by using infiltration based, low impact storm water management. We describe a group of preliminary experiments using relatively simple engineering tools to compare three basic scenarios of development: an undeveloped landscape; a fully developed landscape using traditional, high impact storm water management; and a fully developed landscape using infiltration based, low impact design. Based on these experiments, it appears that by manipulating the layout of urbanized landscapes, it is possible to reduce impacts on hydrology relative to traditional, fully connected storm water systems. However, the amount of reduction in impact is sensitive to both rainfall event size and soil texture, with greatest reductions being possible for small, relatively frequent rainfall events and more pervious soil textures. Thus, low impact techniques appear to provide a valuable tool for reducing runoff for the events that see the greatest relative increases from urbanization: those generated by the small, relatively frequent rainfall events that are small enough to produce little or no runoff from pervious surfaces, but produce runoff from impervious areas. However, it is clear that there still needs to be measures in place for flood management for larger, more intense, and relatively rarer storm events, which are capable of producing significant runoff even for undeveloped basins.

Kim, HH; Seagren, EA; Davis, AP. 2003. Engineered bioretention for removal of nitrate from stormwater runoff. WATER ENVIRONMENT RESEARCH, 75 (4): 355-367.

Abstract: A bioretention unit is a simple, plant- and soil-based, low-impact treatment and infiltration facility for treating stormwater runoff in developed areas. Nitrate, however, is not attenuated in conventional bioretention facilities. Thus, this study systematically evaluated a reengineered concept of bioretention for nitrate removal via microbial denitrification, which incorporates a continuously submerged anoxic zone with an overdrain. Experimental studies were performed in four phases. In the first two phases, column studies demonstrated that, overall, newspaper is the best solid-phase electron-donor substrate for denitrification out of the set studied (alfalfa, leaf mulch compost, newspaper, sawdust, wheat straw, wood chips, and elemental sulfur) based on superior nitrate removal and effluent water quality. The nitrate loading and hydraulic loading studies in the second phase provided design information. In the third phase, system viability after 30- and 84-day dormant periods was evaluated in column studies, demonstrating that newspaper-supported biological denitrification should be effective under conditions of intermittent loadings. Finally, in the fourth phase, pilot-scale bioretention studies demonstrated the effectiveness of the proposed design, showing nitrate plus nitrite mass removals of up to 80%. These results indicate that engineered bioretention for the removal of nitrogen from stormwater runoff has the potential for successful application as an urban stormwater treatment practice.

Li, H, et al. 2009. Mitigation of Impervious Surface Hydrology Using Bioretention in North Carolina and Maryland. JOURNAL OF HYDROLOGIC ENGINEERING, 14 (4): 407-415.

Abstract: As an increasingly adopted storm water best management practice to remedy hydrologic impairment from urban imperviousness, bioretention facilities need rigorous field performance research and monitoring to confirm performance and improve design and maintenance recommendations. This study investigated hydrologic performance at six bioretention cells in Maryland [College Park (CP), a 181 m(2) cell, 50-80 cm media depth, monitored for 22 events, and Silver Spring (SS), a 102 m(2) cell, 90 cm media depth, monitored for 60 events] and North Carolina [Greensboro (G1 and G2), each approximately 317 m(2), 120 cm media depth, both monitored for 46 events, and Louisburg (L1=surface area of 162 m(2), L2=surface area of 99 m(2)); each had 50-60 cm fill depths, monitored for 31 and 33 events, respectively] over 10-15 month periods. Outflow from each cell was recorded and inflow was either recorded or calculated from rainfall data. In Louisburg, L2 was lined with an impermeable membrane to eliminate exfiltration while L1 was unlined to allow both exfiltration and evapotranspiration. Results indicate that bioretention facilities can achieve substantial hydrologic benefits through delaying and reducing peak flows and decreasing runoff volume. A large cell media volume: drainage area ratio, and adjustments to the drainage configuration appear to improve the performance. Media layer depth may be the primary design parameter controlling hydrologic performance. Performance diminishes as rainfall depths increase and rainfall durations become longer. Annual water budget analysis suggests that approximately 20-50% of runoff entering the bioretention cells was lost to exfiltration and evapotranspiration.

Maxted, JR, Shaver, E. 1999. The Use of Retention Basins to Mitigate Stormwater Impacts to Aquatic Life. National Conference on Retrofit Opportunities for Water Resource Protection in Urban Environments: Proceedings, Chicago, IL, February 9-12, 1998. Pp. 6-15.

Rushton, Betty. 1999. Low Impact Parking Lot Design Reduces Runoff and Pollutant Loads. Proceedings of the Sixth Biennial Stormwater Research and Watershed Management Conference, September 14-17, 1999, Tampa, Florida. Pp. 90-101.

ABSTRACT: An innovative parking lot at the Florida Aquarium in Tampa, Florida is being used as a research site and demonstration project to show how small alterations to parking lot designs can dramatically decrease runoff and pollutant loads. Three paving surfaces are compared as well as basins with and without swales to measure pollutant concentrations and infiltration. Preliminary results from sixteen storms indicate that for rainfall less than two centimeters, the basins with swales and permeable paving have 85 to 95 percent less runoff than the basins without swales, and 60 to 80 percent less runoff than the other basins with swales. Larger rain events do not show as much difference in runoff amounts from different paving types but basins with swales have about 40 percent less runoff than the two basins without swales. Rainfall water quality and quantity are also evaluated and rain is found to be a significant input for inorganic nitrogen. Other water quality data how higher phosphorus concentrations in basins with vegetated swales, and higher metal concentrations in basins paved with asphalt rather than cement or permeable paving. Sediment samples exhibit the same trends as water quality samples with higher phosphorus concentrations in basins with swales and higher metal concentrations in basins paved with asphalt. Polycyclic Aromatic Hydrocarbons (PAH) and pesticides were detected in the sediments at almost all sites sampled.

Sansalone, J; Teng, Z. 2004. In situ partial exfiltration of rainfall runoff. I: Quality and quantity attenuation. JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE, 130 (9): 990-1007.

Abstract: Rainfall runoff impacted by anthropogenic activities transports significant quantities of particulate, aqueous, and complexed constituents. These diffuse, unsteady, and stochastic event-based loadings are unique challenges for water quality (concentration, mass) and quantity control (volume, peak flow). While many infiltration/exfiltration structural best management practices (BMPs) or low impact development practices are implemented, few in situ data sets are examined for actual events and temporal-based BMP behavior, in part due to costs of such examinations. Fewer studies provided a statistical and mechanistic interpretation for event-based BMP performance. The design, water quality, and quantity functions of a partial exfiltration reactor (PER) utilizing Fe-coated sand is examined specifically across three water quality type rainfall-runoff events over a 10-month period. Reduction of total concentrations for metals (Zn, Pb, Cu, and Cd), ranged from 24 to 93%, while total mass reductions ranged from 57 to 98% due to exfiltration. Reduction in total suspended solids concentrations ranged from 23 to 86% while reduction in total mass ranged from 69 to 96%. Chemical oxygen demand concentrations reductions ranged from 37 to 70%. Storm water volume reductions ranged from 55 to 70% through variably saturated exfiltration to surrounding clayey glacial till soils (K-sat = 10(-6) cm/s), while peak flow reductions ranged from 36 to 85%. Results of statistical analysis indicate that a passive downflow PER is capable of functioning as an in situ water quality and quantity control BMP for rainfall runoff. Results indicate that as structural and nonstructural controls are implemented, monitoring, examination, and understanding of event-based and life-cycle performance are critical to achieve both quantity and quality goals.

Shuster, WD, Gehring, R, Gerken, J. 2007. Prospects for enhanced groundwater recharge via infiltration of urban storm water runoff: A case study. JOURNAL OF SOIL AND WATER CONSERVATION, 62 (3): 129-137

Abstract: The rain garden is an urban storm water best management practice that is used to infiltrate runoff close to its source, thereby disconnecting impervious area while providing an avenue for groundwater recharge. Groundwater recharge may provide additional benefits to aquatic ecosystems via enhancement of stream base flow.Yet, soil conditions can impact on certain aspects of rain garden performance and its provision of ecosystem services. In the context of a watershed-level study to determine the effectiveness of decentralized storm water management, we performed an order 1 soil survey of the Shepherd Creek watershed (Cincinnati, Ohio) to delineate soils and identify and describe representative soil pedons, and then we assessed subsoil saturated hydraulic conductivity (K-sat) in each of the three dominant subsoils with qualitative estimation methods and directly with constant-head permeametry. We next simulated the effect of subsoil hydrology of a hypothetical implementation of a parcel-level rain garden on groundwater recharge in this watershed. Measured subsoil K-sat were overall very low with a mean of 0.01 cm hr(-1) (4 x 10(-3) in hr(-1)) for Eden soil and a mean of 0.2 cm hr(-1) (0.08 in hr(-1)) for both the fine-silty family and Switzerland soils. Compared with the measured values, qualitative measures overestimated K-sat and depth of recharge for Eden and fine-silty, and underestimated the same for Switzerland. Based on median parcel features and 2004 warm-season storm records, rain gardens in the fine-silty family and Switzerland subsoils would be expected to contribute about 6 cm (2.4 in) of recharge as compared to the 2 cm (0.8 in) expected in Eden soils. Our results also suggest the highest potential for abatement of storm water quantity abatement in Eden soils, with some partitioning of this water to recharge as an added benefit. Our approach and results form the basis for a comprehensive understanding of how storm water management decentralized at the watershed level may positively impact ecosystem services.

Teng, Z; Sansalone, J. 2004. In situ partial exfiltration of rainfall runoff. II: Particle separation. JOURNAL OF ENVIRONMENTAL ENGINEERING-ASCE, 130 (9): 1008-1020.

Abstract: Metal elements or other constituents transported in urban and transportation land use rainfall runoff are often adsorbed on or incorporated with entrained particles that are ubiquitous in such runoff. Infiltration-exfiltration can be an effective in situ particle separation and quantity control structural best management practices or low impact development practices allowing runoff to return to soil after passive physical-chemical treatment. The in situ partial exfiltration reactor (PER), which combined the surface straining of the cementitious porous pavement (CPP) layer with filtration of oxide coated sand media beneath, provided control of water quantity and quality. Particle analyses were carried out for both influent and effluent to examine filter efficiency as a function of particle size and hydrology. Influent d(m)/d(p) ratios suggest that the dominant PER particle separation mechanisms were unsaturated physical-chemical filtration with the CPP layer functioning as a straining surface. Particle size distributions were modeled based on a two-parameter cumulative power-law function. The performance of the PER as a filter is shown to be a function of the unsteady site hydrology. Temporal variation in the filter coefficient and the volumetric particle fraction remaining were directly related to the unsteady influent loading rate. Particle removal efficiency by the PER based on concentration ranged from 71 to 96% on a mass-based concentration and 92-99% on a number based concentration. Results suggest that a properly designed PER can provide effective in situ control for particles and could be combined with or function separately from source control (i.e., pavement cleaning or a mass trading framework).

Zhen, J, et al. 2006. BMP analysis system for watershed-based stormwater management. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING, 41 (7): 1391-1403.

Abstract: Best Management Practices (BMPs) are measures for mitigating nonpoint source (NPS) pollution caused mainly by stormwater runoff. Established urban and newly developing areas must develop cost effective means for restoring or minimizing impacts, and planning future growth. Prince George's County in Maryland, USA, a fast-growing region in the Washington, DC metropolitan area, has developed a number of tools to support analysis and decision making for stormwater management planning and design at the watershed level. These tools support watershed analysis, innovative BMPs, and optimization. Application of these tools can help achieve environmental goals and lead to significant cost savings. This project includes software development that utilizes GIS information and technology, integrates BMP processes simulation models, and applies system optimization techniques for BMP planning and selection. The system employs the ESRI ArcGIS (c) as the platform, and provides GIS-based visualization and support for developing networks including sequences of land uses, BMPs, and stream reaches. The system also provides interfaces for BMP placement, BMP attribute data input, and decision optimization management. The system includes a stand-alone BMP simulation and evaluation module, which complements both research and regulatory nonpoint source control assessment efforts, and allows flexibility in the examining various BMP design alternatives. Process based simulation of BMPs provides a technique that is sensitive to local climate and rainfall patterns. The system incorporates a meta-heuristic optimization technique to find the most cost-effective BMP placement and implementation plan given a control target, or a fixed cost. A case study is presented to demonstrate the application of the Prince George's County system. The case study involves a highly urbanized area in the Anacostia River (a tributary to Potomac River) watershed southeast of Washington, DC. An innovative system of management practices is proposed to minimize runoff, improve water quality, and provide water reuse opportunities. Proposed management techniques include bioretention, green roof, and rooftop runoff collection (rain barrel) systems. The modeling system was used to identify the most cost-effective combinations of management practices to help minimize frequency and size of runoff events and resulting combined sewer overflows to the Anacostia River.



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