Scott D. Struck

Role of Stream Restoration on Improving Benthic Macroinvertebrates and In-Stream Water Quality in an Urban Watershed: Case Study

Many stream restoration projects do not include a requirement for long-term monitoring after the project has been completed, resulting in a lack of information about the success or failure of certain restoration techniques. The National Risk Management Research Laboratory, part of the U.S. EPA Office of Research and Development, evaluated the effectiveness of stream bank and channel restoration as a means of improving in-stream water quality and biological habitat in Accotink Creek, Fairfax City, Va., using discrete sampling and continuous monitoring techniques before and after restoration. This project monitored the effects of a 549 m (1,800 linear-ft) restoration of degraded stream channel in the North Fork of Accotink Creek. Restoration, which was intended to restore the stream channel to a stable condition, thereby reducing stream bank erosion and sediment loads in the stream, included installation of native plant materials along the stream and bioengineering structures to stabilize the stream channel and bank. Results of sampling and monitoring for 2 years after restoration indicated a slight improvement in biological quality for macroinvertebrate indices such as Virginia Stream Condition Index, Hilsenhoff Biotic Index, and Ephemeroptera, Plecoptera, Trichoptera taxa; the differences were statistically significant at 90% level of confidence with the power of greater than 0.8. However, indices were all below the impairment level, indicating poor water quality conditions. No statistically significant differences in chemical constituents and bacteriological indicator organisms were found before and after restoration as well as upstream and downstream of the restoration. The results indicated that stream restoration alone had little effect in improving the conditions of in-stream water quality and biological habitat, though it has lessened further degradation of stream banks in critical areas where the properties were at risk. Control of storm-water flows by placing best management practices in the watershed might reduce and delay discharge to the stream and may ultimately improve habitat and water quality conditions.

Evaluating the accotink creek restoration project for improving water quality, in-stream habitat, and bank stability

Increased urbanization results in a larger percentage of connected impervious areas and can contribute large quantities of stormwater runoff and significant quantities of debris and pollutants (e.g., litter, oils, microorganisms, sediments, nutrients, organic matter, and heavy metals) to receiving waters. To improve water quality in urban and suburban areas, watershed managers often incorporate best management practices (BMPs) to reduce the quantity of runoff as well as to minimize pollutants and other stressors contained in stormwater runoff. It is well known that land-use practices directly impact urban streams. Stream flows in urbanized watersheds increase in magnitude as a function of impervious area and can result in degradation of the natural stream channel morphology affecting the physical, chemical, and biological integrity of the stream. Stream bank erosion, which also increases with increased stream flows, can lead to bank instability, property loss, infrastructure damage, and increased sediment loading to the stream. Increased sediment loads may lead to water quality degradation downstream and have negative impacts on fish, benthic invertebrates, and other aquatic life. Accotink Creek is in the greater Chesapeake Bay and Potomac watersheds, which have strict sediment criteria. The USEPA (United States Environmental Protection Agency) and USGS (United States Geological Survey) are investigating

Special Issue on Urban Storm-Water Management in the 21st Century

As the practice of storm-water management evolves, so has our understanding of the tools. As we move away from a myopic flood control perspective, new tools to include what we now call green infrastructure best management practices (BMPs) were developed. Green roofs, rain gardens, and porous pavements appeared, with much of the design elements based on reasonable estimates of performance, thus the term “best.” Now we as a profession are moving toward a more engineered approach, with designs based on scientific knowledge of the processes, from soil physics and chemistry to hydrology and hydraulics. Soon it may be time to retire BMPs and move forward with the term “storm-water control measures,” as recommended by the National Academies authors of Urban Stormwater in the United States (National Research Council 2008). This issue of the Journal of Irrigation and Drainage Engineering is devoted to this evolving field of storm-water sustainability, and the effort to predict performance of our storm-water control measures. The 10 papers in this special issue reflect this evolution. Papers range from evaluating the concentration of effluent scoured from catch basins to cost-estimation tools, plus the inclusion of green-infrastructure tools within the International Stormwater BMP Database. Green and stone roofs are represented as are level spreaders. Bioretention/bioinfiltration rain gardens, however, received the most attention with papers on media depth, phosphorus removal, process modeling, mounding, and fines accumulation. This collection truly demonstrates our increasing knowledge base. This effort is a result of collaboration between the Stormwater Infrastructure Committee and Urban Water Resources Research Council, together with the Journal of Irrigation and Drainage Engineering Publications Committee. Conference proceedings from recent Environmental and Water Resources Institute (EWRI) congresses and low-impact development (LID) conferences were reviewed, and a select group of authors was invited to expand and revise their work. These papers passed through the standard journal peer-review process. We hope that this set of papers is of use to the profession. We would like to thank all the contributing authors, the reviewers, and William Ritter, as editor, for their efforts in this special issue.

Performance of Retention Ponds and Constructed Wetlands for Attenuating Bacterial Stressors

Microbial contamination from fecal origins in stormwater runoff poses a risk to human health through the consumption of drinking water and recreational and bathing contact with surface waters. Indicator bacteria serve as the regulatory meter by which water quality is measured and water quality standards (WQS) must be met. Research on constructed wetlands inactivation of fecal indicators in secondary and animal wastewater is well documented (Bavor et al., 1987; Gersberg et al., 1987; Ottova et al., 1997). Removals of fecal streptococci and coliforms generally exceeded 80% and 90%, respectively, in a review by Kadlec and Knight, 1996. Gersberg et al. (1987) and Garcia and Becares (1997) concluded that extensively vegetated systems remove indicator bacteria at significantly higher rates from wastewater than unvegetated systems. However, because of the potentially high indicator bacteria concentrations in stormwater runoff, the untreated fraction in effluent from retention ponds and constructed wetlands may increase receiving water concentrations beyond WQS. This is in contrast to separate sanitary systems and combined stormwater and sanitary systems which, other than during sewer overflow conditions, chemically treat the wastewater routed to treatment plants.

The Role of Stormwater Research in BMP DesignPathogens and Regulatory Demands

The U.S. Environmental Protection Agency strives to protect human health, ensure the safety of drinking and recreational waters, support economic and recreational activities, and provide healthy habitat for fish, plants, and wildlife. To accomplish these objectives, the Agency emphasizes restoring and maintaining our oceans, watersheds, and their aquatic ecosystems. Urbanization results in more impervious areas that cause larger quantities of stormwater runoff. This runoff can contribute significant amounts of pollutants (e.g., litter, oils, microorganisms, sediments, nutrients, organic matter, and heavy metals) to receiving waters. To improve water quality in urban and suburban areas, watershed managers often incorporate structural best management practices (BMPs) to remove or reduce pollutants contained in stormwater runoff. In this project, constructed wetlands and retention ponds were evaluated for reducing microbial concentrations from urban stormwater runoff. Several studies have looked at the capabilities of these BMPs to reduce pollutant concentrations and loadings. Few studies, however, have focused on the internal mechanisms occurring in these BMPs and fewer yet on using these BMPs for treating microbial pollutants. Preliminary results indicate both types of BMPs can lower microbial concentrations from urban stormwater runoff. Retention ponds had greater removal rates for enterococci and E. coli in June and September sampling events. However, further reduction may be limited by irreducible concentrations contained in the urban stormwater runoff and/or the sediments entering into or existing within the BMPs. The disparity in results may be due to light, temperature, and predation differences between the two treatments.

Prioritization of Green Infrastructure for CSO Communities - Identifying Effective Implementation Opportunities

Combined sewer systems (CSS) are under regulatory mandate to reduce or treat combined sewer overflow (CSO) discharges in order to protect receiving waters. Under the requirements of the Clean Water Act, municipalities are responsible for developing comprehensive long-term control plans (LTCPs). These plans must identify a selected alternative, a level of control and a schedule for reducing discharges. Historically, CSO control methods included various approaches to manage the excess flows, including storage, remote treatment and conveyance to a centralized treatment plant or sewer separation. Many of the plans developed subsequent to 2007 include an approach which relies on green infrastructure and similar stormwater source controls. Green infrastructure includes practices and sitedesign techniques that store, infiltrate, evaporate, or detain stormwater runoff and in so doing, control the timing and volume of stormwater discharges from impervious surfaces (e.g., streets, building roofs, and parking lots) to the sewer system. In order to determine the most effective use of green infrastructure, municipalities are evaluating a number of strategies and approaches to its application. Implementation must consider site-specific issues in each community and the opportunities for cost effective implementation. An evaluation of 12 municipal programs that incorporate green infrastructure into their LTCP was performed in 2011. This paper summarizes the various approaches that municipalities used for evaluating green infrastructure. Those approaches included GIS evaluations, modeling and cost / benefit assessments.

Advanced Drainage Concepts Using Green Solutions for CSO Control — The KC Approach

Advanced design concepts such as Low Impact Development (LID) and Green Solutions (or upland runoff control techniques) are currently being encouraged by the U.S.EPA (EPA) as a management practice to contain and control stormwater at the lot or upland residential parcel level. These controls have shown that when implemented and maintained properly, they can increase retention at the runoff source — decreasing the runoff volume entering the drainage system and the demand on a drainage system. Both developed storm and combined sewersheds can benefit from the added storage from areas retrofitted with bioretention cells or rain gardens and other management, e.g., catchbasin retrofits or curb-cuts with tree planting. This paper documents an effort by the U.S. EPA to demonstrate the efficacy of implementing integrated, green infrastructure-based solutions to wet- weather flow pollution problems in and urban core neighborhood within a combined sewer system. The project involves local and regional efforts to provide the basis for success of the implementation of green infrastructure and stormwater management at the neighborhood, watershed, and regional levels. Specifically, the project will demonstrate the strategy and methodology for where and how attainment of Green Solutions will be implemented, including model support, within Kansas City, Missouri.

Nutrient-Based ecological considerations for stormwater management basins: Ponds and wetlands

The effects of stormwater pond and wetland best management practice (BMP) designs on phosphorus and nitrogen concentrations in effluent was considered using extant data and experimental observations from pond and wetland mesocosms. Relative difference between BMP types were evaluated with respect to several nutrient forms and in relation to untreated stormwater runoff. The mesocosms allowed for direct measurement of time integrated nutrient influent and effluent mass loading. Based on an extended effluent monitoring protocol, these BMP treatments tended to have little effect on total nutrient mass differences between influent and effluent loads. However, significant nitrate removal from BMP influent was observed and appeared to be controlled by influent concentration. The observed nutrient concentrations in BMP effluent could be explained by the reservoir of exchangeable nutrient in basin pore water and the nature of primary production within a BMP type; phytoplankton vs. macrophyte dominance. For example, wetlands tended toward lower effluent phosphorus loading than ponds, which coincided with lower pore water soluble phosphorus pools that were driven by sequestration in macrophyte tissues. Ponds showed a greater potential for effluent nutrient loading than wetlands, which was partly a function of the lower runoff volume to permanent pool volume ratios (Vr:Vb) in pond design. Overall the data suggest little potential for sustained total nutrient removal in these basins at influent loads typical of urban stormwater runoff. Due to the nature of nutrient cycling in mature pond and wetland systems, we suggest a refocusing toward temporallyextended BMP effluent monitoring for better estimation of their effects on nutrient load quantity and quality for TMDLs.