Roger T. Bannerman

From streets to streams: Assessing the toxicity potential of urban sediment by particle size

Urban sediment can act as a transport mechanism for a variety of pollutants to move towards a receiving water body. The concentrations of these pollutants oftentimes exceed levels that are toxic to aquatic organisms. Many treatment structures are designed to capture coarse sediment but do not work well to similarly capture the fines. This study measured concentrations of select trace metals and PAHs in both the silt and sand fractions of urban sediment from four sources: stormwater bed, stormwater suspended, street dirt, and streambed. Concentrations were used to assess the toxic potential of sediment based on published sediment quality guidelines. All sources of sediment showed some level of toxic potential with stormwater bed sediment the highest followed by stormwater suspended, street dirt, and streambed. Both metal and PAH concentration distributions were highly correlated between the four sampling locations suggesting the presence of one or perhaps only a few sources of these pollutants which remain persistent as sediment is transported from street to stream. Comparison to other forms of combustion- and vehicle-related sources of PAHs revealed coal tar sealants to have the strongest correlation, in both the silt and sand fractions, at all four sampling sites. This information is important for environmental managers when selecting the most appropriate Best Management Practice (BMP) as a way to mitigate pollution conveyed in urban stormwater from source to sink.

Linking biomarkers to reproductive success of caged fathead minnows in streams with increasing urbanization.

Reproductive and oxidative stress biomarkers have been recommended as tools to assess the health of aquatic organisms. Though validated in the laboratory, there are few studies that tie a change in gene expression to adverse reproductive or population outcomes in the field. This paper looked at 17 streams with varying degrees of urbanization to assess the use of biomarkers associated with reproduction or stress in predicting reproductive success of fathead minnows. In addition, the relationship between biomarkers and water quality measures in streams with varying degrees of urbanization was examined. Liver vitellogenin mRNA was correlated with reproduction within a period of 11d prior to sampling irrespective of habitat, but its correlation with egg output declined at 12d and beyond indicating its usefulness as a short-term biomarker but its limits as a biomarker of total reproductive output. Stress biomarkers such as glutathione S-transferase may be better correlated with factors affecting reproduction over a longer term. There was a significant correlation between GST mRNA and a variety of anthropogenic pollutants. There was also an inverse correlation between glutathione S-transferase and the amount of the watershed designated as wetland. Egg production over the 21-d was negatively correlated with the amount of urbanization and positively correlated to wetland habitats. This study supports the development of multiple biomarkers linking oxidative stress and other non-reproductive endpoints to changes in aquatic habitats will be useful for predicting the health of fish populations and identifying the environmental factors that may need mitigation for sustainable population management.

Relationships between impervious surfaces within a watershed and measures of reproduction in fathead minnows (Pimephales promelas)

Urban regions have a high percentage of impervious surfaces which are critical nonpoint pollution sources. To evaluate the role of impervious surfaces on stream quality, a mobile field station was constructed into which stream water was pumped. Study sites were located within one low, two intermediate and two high percent impervious surface watersheds. Stream water entered three 20-gallon, flow-through aquaria which were divided by 1/8′′ mesh plastic screen into four equal compartments, each containing one male-female fathead minnow breeding pair (n= 12 pairs), and one 4′′ diameter PVC tube (4′′×4′′, cut lengthwise) as a breeding substrate. Temperature within the mobile unit (18–25 °C) maintained by air conditioners or heaters; water temperature in the aquaria (20–24 °C) maintained by aquarium heaters. Daily observations included: reproductive behavior, development of male secondary sexual characteristics, and egg counts. Time spent conducting nest and/or egg care activities, average daily spawn attempts, development of male secondary sexual characteristics (tubercles, dorso-ventral banding, head and body coloration) and male-initiated chasing of female were directly related to percent impervious surface in the watershed (ANOVA, p < 0.05). While spawning frequency and average day to first oviposition were not significantly different between study sites, average daily egg count, number of pairs breeding per day and number of eggs per breeding pair were all associated with land use patterns (ANOVA, p < 0.05). Using reproductive measures in a mobile field station show promise as a flexible method of evaluating water quality in watersheds in urban and urbanizing regions.

Sources of Pollutants in Urban Areas (Part 1) - Older Monitoring Projects

Information concerning source area runoff characteristics during wet weather events can be very important when developing stormwater management plans that inco…

Verification of a depth-integrated sample arm as a means to reduce solids stratification bias in urban stormwater sampling

A new water sample collection system was developed to improve representation of solids entrained in urban stormwater by integrating water-quality samples from the entire water column, rather than a single, fixed point. The depth-integrated sample arm (DISA) was better able to characterize suspended-sediment concentration and particle size distribution compared to fixed-point methods when tested in a controlled laboratory environment. Median suspended-sediment concentrations overestimated the actual concentration by 49 and 7% when sampling the water column at 3- and 4-points spaced vertically throughout the water column, respectively. Comparatively, sampling only at the bottom of the pipe, the fixed-point overestimated the actual concentration by 96%. The fixed-point sampler also showed a coarser particle size distribution compared to the DISA which was better able to reproduce the average distribution of particles in the water column over a range of hydraulic conditions. These results emphasize the need for a water sample collection system that integrates the entire water column, rather than a single, fixed point to properly characterize the concentration and distribution of particles entrained in stormwater pipe flow.

The Role of Street Cleaning in Stormwater Management

The authors have been involved in numerous street cleaning research projects for over 30 years. This paper will give us a unique opportunity to highlight the historical use of street cleaning as a method for reducing stormwater pollutants, and will examine newly emerging street cleaning technologies. There have been many misconceptions concerning this potential stor mwater management control. This paper will examine the limitations of street cleaning, and descr ibe how it can be more effective. Street cleaning plays an important role in most public works departments a s an aesthetic and safety control measure. Street cleaning is also important to reduce massive dirt an d debris buildups present in the spring in the northern regions. Leaf cleanup by street cleaning is also necessary in most areas in the fall. Early Street Cleaning Tests Factors significantly affecting street cleaning performan ce include particle loadings, street texture, street moisture, parked car conditions, and equipment operating conditions (Pitt 1979). If the 500-1000 μm particle loadings are less than about 75 kg/curb-km for smo oth asphalt streets, conventional street cleaning does little good. As the loadings increase, so do th e removals: with loadings of about 10 kg/curb-km, less than 25 percent removals can be expected, while removals of up to about 50 percent can be expected if the initial loadings are as high as 40 kg/curb-km for this particle size. The removal performance decreases substantially for smaller partic les, including those that are most readily washed off the street during rains and contribute to stormwater pollution. Much information concerning street cleaning productivity has be en collected previously in many areas. The early tests (Sartor and Boyd 1972) were conducted in con trolled strips using heavy loadings of simulates instead of natural street dirt at typical loa dings. Later tests, from the mid 1970s to mid 1980s, were conducted in large study areas (20 to 200 ha) by measuring actual street dirt loadings on many street segments immediately before and after typical street cleaning. These large-scale tests are of most interest, as they monitored both street surface phenomen a and runoff characteristics. Many if these tests were conducted as part of the Nationwide Urban Runoff Pro gram (NURP) directed by the EPA (1983). The following list briefly describes these large-scale street cleaning performance tests:

Development of a depth-integrated sample arm to reduce solids stratification bias in stormwater sampling

A new depth-integrated sample arm (DISA) was developed to improve the representation of solids in stormwater, both organic and inorganic, by collecting a water quality sample from multiple points in the water column. Data from this study demonstrate the idea of vertical stratification of solids in storm sewer runoff. Concentrations of suspended sediment in runoff were statistically greater using a fixed rather than multipoint collection system. Median suspended sediment concentrations measured at the fixed location (near the pipe invert) were approximately double those collected using the DISA. In general, concentrations and size distributions of suspended sediment decreased with increasing vertical distance from the storm sewer invert. Coarser particles tended to dominate the distribution of solids near the storm sewer invert as discharge increased. In contrast to concentration and particle size, organic material, to some extent, was distributed homogenously throughout the water column, likely the result of its low specific density, which allows for thorough mixing in less turbulent water.

Sources of Pollutants in Urban Areas (Part 2) - Recent Sheetflow Monitoring

Two research projects that examined source area sheetflows that were conducted in the 1990s are high-lighted in this chapter. These are a comprehensive project…

Highway-runoff quality, and treatment efficiencies of a hydrodynamic-settling device and a stormwater-filtration device in Milwaukee, Wisconsin

The treatment efficiencies of two prefabricated stormwater-treatment devices were tested at a freeway site in a high-density urban part of Milwaukee, Wisconsin. One treatment device is categorized as a hydrodynamic-settling device (HSD), which removes pollutants by sedimentation and flotation. The other treatment device is categorized as a stormwater-filtration device (SFD), which removes pollutants by filtration and sedimentation. During runoff events, flow measurements were recorded and water-quality samples were collected at the inlet and outlet of each device. Efficiency-ratio and summation-of-load (SOL) calculations were used to estimate the treatment efficiency of each device. Event-mean concentrations and loads that were decreased by passing through the HSD include total suspended solids (TSS), suspended sediment (SS), total phosphorus (TP), total copper (TCu), and total zinc (TZn). The efficiency ratios for these constituents were 42, 57, 17, 33, and 23 percent, respectively. The SOL removal rates for these constituents were 25, 49, 10, 27, and 16 percent, respectively. Event-mean concentrations and loads that increased by passing through the HSD include chloride (Cl), total dissolved solids (TDS), and dissolved zinc (DZn). The efficiency ratios for these constituents were -347, -177, and 20 percent, respectively. Four constituents—dissolved phosphorus (DP), chemical oxygen demand (COD), total polycyclic aromatic hydrocarbon (PAH), and dissolved copper (DCu)—are not included in the list of computed efficiency ratio and SOL because the variability between sampled inlet and outlet pairs were not significantly different. Event-mean concentrations and loads that decreased by passing through the SFD include TSS, SS, TP, DCu, TCu, DZn, TZn, and COD. The efficiency ratios for these constituents were 59, 90, 40, 21, 66, 23, 66, and 18, respectively. The SOLs for these constituents were 50, 89, 37, 19, 60, 20, 65, and 21, respectively. Two constituents—DP and PAH —are not included in the lists of computed efficiency ratio and SOL because the variability between sampled inlet and outlet pairs were not significantly different. Similar to the HSD, the average efficiency ratios and SOLs for TDS and Cl were negative. Flow rates, high concentrations of SS, and particle-size distributions (PSD) can affect the treatment efficacies of the two devices. Flow rates equal to or greater than the design flow rate of the HSD had minimal or negative removal efficiencies for TSS and SS loads. Similar TSS removal efficiencies were observed at the SFD, but SS was consistently removed throughout the flow regime. Removal efficiencies were high for both devices when concentrations of SS and TSS approached 200 mg/L. A small number of runoff events were analyzed for PSD; the average sand content at the HSD was 33 percent and at the SFD was 71 percent. The 71-percent sand content may reflect the 90-percent removal efficiency of SS at the SFD. Particles retained at the bottom of both devices were largely sand-size or greater. First posted August 4, 2011 Report PDF (4.75 MB) For additional information contact: Director, Wisconsin Water Science Center U.S. Geological Survey 8505 Research Way Middleton, WI 53562 http://wi.water.usgs.gov/ Part or all of this report is presented in Portable Document Format (PDF); Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.