ArticleLiterature Review

Cold climate BMPs: Solving the management puzzle

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Abstract

Snowmelt runoff and rain-on-snow events present some of the highest pollutant loading and most difficult management challenges in the course of a year in regions with cold climate. Frozen conduits, thick ice layers, low biological activity, altered chemistry, and saturated or frozen ground conditions all work against effective treatment of melt runoff. Understanding the source, evolution and transition that occurs within a melt event, and defining the management objectives for specific receiving waters will help focus the search for effective management techniques. Solving the management puzzle means putting together a strategy for both soluble and solids-associated water pollutants.

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... The field test reported from 42% to 70% for a less developed bioretention facility to over 90% in a well-developed bioretention facility with good vegetation (Davis et al., 2003). The use of in situ infiltration practices has been recommended as a treatment for urban snowmelt with high concentrations of soluble pollutants (Oberts, 2003 ). Infiltration uses the ion-exchange capacity in the soil, or engineered infiltration media, to adsorb soluble pollutants (Oberts, 2003). ...
... The use of in situ infiltration practices has been recommended as a treatment for urban snowmelt with high concentrations of soluble pollutants (Oberts, 2003 ). Infiltration uses the ion-exchange capacity in the soil, or engineered infiltration media, to adsorb soluble pollutants (Oberts, 2003). For successful infiltration of meltwater, adequate infiltration rates are very important, 1.3 cm/h as a minimum rate and clay contents less than 30% have been reported in the literature (Caraco and Claytor, 1997). ...
... Granular or porous frost, however, will maintain and can even exceed the infiltration capacity of the unfrozen soil (Granger et al., 1984; Kane, 1980). The use of biological elements in treatment systems for meltwater, such as the use of vegetated swales with plant roots to enhance infiltration, and vegetated cover to promote sheet flow has been reported as recommended modifications to cold climate best management practices (BMPs) (Oberts, 2003; Caraco and Claytor, 1997). These findings suggest that bioretention offers a great possibility for use both as a snow deposit and for the retention of pollutants from the meltwater . ...
Article
Snow accumulating in urban areas and alongside roads can accumulate high pollutant loads and the subsequent snowmelt can produce high pollutant loads in receiving waters. This paper examines the treatment of roadside snowmelt in bioretention with respect to pollutant removal, pollutant pathways, and major sinks. Bioretention was used to treat snowmelt from three types of urban roads in Trondheim, Norway: residential, medium, and roads with high-density traffic. Metal retention in bioretention boxes had a mass reduction in zinc, copper, lead, and cadmium in the range of 89-99%, and a decrease in outflow concentrations in the range 81-99%. Cadmium was only measured in the water samples, while the other three metals were traced through the system to identify the main sinks. The top mulch layer was the largest sink for the retained metals, with up to 74% of the zinc retained in this mulch layer. The plant metal uptakes were only 2-8% of the total metal retention; however, the plants still play an important role with respect to root zone development and regeneration, which fosters infiltration and reduces the outflow load. Dissolved pollutants in snowmelt tend to be removed with the first flush of meltwater, creating an enrichment ratio with respect to the average pollutant concentrations in the snow. The effect of this enrichment ratio was examined through the bioretention system, and found to be less predominant than that typically reported for untreated snowmelt. The enrichment factors were in the range of 0.65-1.51 for the studied metals.
... Under ice, flow can sometimes be 'pressurized', thus increasing velocity, reducing residence times and even causing bed scour (Oberts et al., 1989). Oberts (2003) states that whether scour occurs is a function of ice thickness, bottom roughness and material, and inflow characteristics (volume, velocity, temperature). Marsalek et al. (2003) found that inflows of comparatively warm base flow in the Kingston pond meant that the ice cover had an uneven depth, which led to the development of preferential pathways. ...
... This has a potentially huge impact on the ability of ponds to function seasonally as the primary removal process is sedimentation. Similarly, it has been suggested that 169 high concentrations of chloride coupled with depleted oxygen may lead to the release of substances, including metals, held in bottom sediments (Marsalek and Marsalek, 1997;Oberts, 2003). Marsalek et al. (2003) found no evidence of this at the Kingston pond, but noted that the pond was rarely anoxic and did not have conductivities (indicative of dissolved salts and, therefore, chloride concentration) as high as other ponds or lakes receiving de-icing salt. ...
... Where salt is used, chemical stratification clearly dominates. In either case, stratification inhibits vertical mixing and aeration of the bottom layer and lowers the sediment settling velocity (Oberts, 2003). Owing to preferential elution of salt, the first melt water can have the highest concentrations of dissolved solids, including metals. ...
Article
Evidence from cold regions in North America has shown that the performance of stormwater ponds differs between winter and summer. The pond hydraulics change seasonally, and winters have lowered removal efficiency due to a combination of an ice cover, cold water and de-icing salts. This study examines the function of the Bckaslov stormwater pond under the more mild conditions of southern Sweden, where there are several snow and melt cycles per year.Event sampling in the summer of 1997 showed good removal efficiencies for nutrients, total suspended solids (TSS) and a selection of metals (Cd, Cu, Pb, Zn), but winter grab-tests taken in 1995–96 and 1997–98 suggest that the pond acts as a pollutant source under cold conditions. To better assess winter and spring pond performance, water at the inflow and outflow was sampled from January to April 2003. The low intensity of runoff delivery and slow inflow velocities meant that time- rather than flow-weighted sampling was used. Five consecutive events were sampled and analysed for TSS, chloride and the metals As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. YSI probes were in place at both the inlet (pH, temperature) and outlet (pH, temperature, conductivity, dissolved oxygen) to determine the timing of pollution flows. In addition, profiles of the same quality indicators allowed snapshots of pond processes.De-icing salt has a major effect on pond hydraulics. Strong stratification occurred after each snowmelt-generated flow event and up to 80% of chloride could be retained by the pond. However, continuous conductivity measurements show that chloride is flushed between events. Ice changes retention times and causes oxygen depletion, but bed scour was not observed. Pond performance decreased during the winter and spring, albeit not as badly as the grab tests suggest. A seasonal comparison of the removal efficiencies showed that removal of Cd (75%) and Cu (49%) was about the same for summer and winter–spring, but removal of Pb, Zn and TSS dropped from 79%, 81% and 80% to 42%, 48% and 49% respectively. The removal efficiencies for the other metals sampled in 2003 were: As, 50%; Cr, 39%; Hg, 56%; Ni, 41%. Copyright © 2005 John Wiley & Sons, Ltd.
... Mild slopes (i.e. 1-4%) (Caraco and Claytor, 1997) Introduction of weirs or grade controls to slow flow (Oberts, 2003) Reduced infiltration in frozen soil, additional snowmelt volumes from snow transfer and rain-on-snow ...
... Modification of the grain size distribution of the turf layer, coarser material recommended Installation of bypass for excess water Increased swale surface storage capacity and minimum infiltration rate of 1.3 mm/h, mild slopes to encourage infiltration (Caraco and Claytor, 1997) Gravel trench to enhance infiltration and release below the frostline (Oberts, 2003) Inflow of de-icing road salt; avoiding toxicity levels of metals by trace metal desorption ...
... Despite impact on removal in bioswales, overall removal probably sufficient (Søberg et al., 2017) Ice-clogged inlets, outlets, culverts Installation of heat cables around critical structures (Backstrom, 2003) Traffic-related pollution surge in spring Snow management strategy: relocation of snowpacks with higher pollution levels to dedicated snow disposal sites to reduce local impact (Sharma et al., 1991) Promotion of meltwater sheet-flow rather than channelized flow to increase pollutant removal (Oberts, 2003) Nutrient discharge due to decomposition of post-seasonal vegetation ...
Article
Full-text available
Swales are the oldest and most common stormwater control measure for conveying and treating roadway runoff worldwide. Swales are also gaining popularity as part of stormwater treatment trains and as crucial elements in green infrastructure to build more resilient cities. To achieve higher pollutant reductions, swale alternatives with engineered media (bioswales) and wetland conditions (wet swales) are being tested. However, the available swale design guidance is primarily focused on hydraulic conveyance, overlooking their function as an important water quality treatment tool. The objective of this article is to provide science-based swale design guidance for treating targeted pollutants in stormwater runoff. This guidance is underpinned by a literature review. The results of this review suggest that well-maintained grass swales with check dams or infiltration swales are the best options for runoff volume reduction and removal of sediment and heavy metals. For nitrogen removal, wet swales are the most effective swale alternative. Bioswales are best for phosphorus and bacteria removal; both wet swales and bioswales can also treat heavy metals. Selection of a swale type depends on the site constraints, local climate, and available funding for design, construction, and operation. Appropriate siting, pre-design site investigations, and consideration of future maintenance during design are critical to successful long-term swale performance. Swale design recommendations based on a synthesis of the available research are provided, but actual design standards should be developed using local empirical data. Future research is necessary to identify optimal design parameters for all swale types, especially for wet swales.
... Within cold, low-gradient, snowmelt-dominated landscapes such as the Canadian Prairies, eutrophication remains a key management issue. Few BMPs, however, have been demonstrated to be effective in such areas, where export of soluble species is high (Oberts, 2003). ...
... Finding BMPs to help control nutrients in cold climates, and where soluble nutrient export is a major concern, has proven to be a significant challenge (Oberts, 2003). Headwater dams are one BMP that helps retain nutrients under these challenging conditions (Tiessen et al., 2011). ...
Article
There are few beneficial management practices (BMPs) with demonstrated efficacy in snowmelt-dominated regions. Small reservoirs are a BMP that can help mitigate flooding and reduce sediment transport, while reducing export of dissolved nutrients. To understand controls on nitrate removal and assess how this ecosystem service can be optimized, denitrification activity was measured in reservoirs and stream pools of the Tobacco Creek Model Watershed (Manitoba, Canada) via the chloramphenicolamended acetylene block technique. Denitrification activity was positively correlated with nitrate and sediment organic carbon (SOC), and negatively correlated with sediment particle size and pH. Reservoirs exhibited higher denitrification activity than stream pools and were associated with higher levels of SOC, higher nitrate in early summer, and lower concentrations of dissolved oxygen. Nitrate was added to a set of samples to test for nitrate saturation, an indicator of poor ecological status, where nitrate concentrations exceed the denitrification capacity of microbes. Forty-nine percent of measurements demonstrated nitrate saturation, indicative of the need for additional remediation activity. Findings from this research suggest this BMP has higher capacity for nitrogen removal than stream pools because of higher denitrification rates and a higher apparent threshold for nitrate saturation, coupled with increased residence times. Results also inform the construction of additional reservoirs, which have been identified as a priority BMP in this region. Siting reservoirs in areas where conditions contribute to buildup of fine sediments and planting riparian vegetation to foster high organic C availability may help optimize denitrification, although tradeoffs in terms of other ecosystem services must be considered. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved.
... In colder climates, research has been conducted to assess bioretention performance for both water quality treatment and hydraulic efficiency as reduced performance is of concern due to freezing of the filter media, high chloride loads due to deicing chemicals, and dormant biological functions due to temperature (Oberts, 2003). Blecken et al. (2010) conducted a bioretention column study to investigate the effect of low temperatures on nutrient removal. ...
... High pollutant loads have been reported by Oberts (2003) in snow that has accumulated in urban areas and alongside roads. Similarly, in warmer climates, pollutant loads on impervious surfaces may accumulate during periods of dry weather. ...
Article
Urbanization leads to water catchments becoming more impervious and channelized. These modifications to the natural landscape result in reduced water infiltration into soils and base flow components that cause a greater volume and rate of surface water runoff. In contrast to conventional stormwater management systems, water-sensitive urban design (WSUD) technologies manage rainfall where it falls, through enhancement of infiltration capacity of impervious areas and rerouting runoff across pervious areas. WSUD aims to better incorporate several urban water sources, including stormwater, into the local hydrological cycle so as to (1) reduce demand on potable water, (2) minimize pollutant loading to surface waters, and (3) restore or maintain predevelopment hydrological processes. Bioretention systems are designed to remove both dissolved pollutants and particulate matter from stormwater runoff and reduce the volume and rate of stormwater discharged. Treatment is achieved via a number of chemical, biological and physical processes including sedimentation, filtration, sorption, reduction, vegetative uptake and microbial biomass assimilation. The efficiency of bioretention systems in the treatment of contaminants in stormwater depends on a number of factors including substrate conditions, type of vegetation, climatic conditions and on the volume and rate of stormwater infiltrated and discharged. This chapter discusses the various processes involved in the treatment of stormwater within bioretention systems; in particular, the fate of nutrients such as nitrogen and phosphorus, and metals, and the soil-plant processes involved in their retention. The factors affecting treatment efficiency are also examined.
... However, in cold climates, snowmelt or rain-on-snow events might be the biggest events of the year; consequently, these events might be more suited for the design of BMPs regarding both quantity and quality issues. During snowmelt, large volumes of runoff, together with large pollutant loads, coincide with frozen ground and lowered infiltration capacity, frozen pipes and inlets/outlets, ice layers, low biological activity, and changed water chemistry (Oberts, 2003). The described cold-climate conditions often lead to a reduced effectiveness of BMPs, implying a need for special considerations when it comes to evaluating design criteria, performance, maintenance, and operation. ...
... Therefore, these events rather than storm events, which are commonly used elsewhere in the world, might be appropriate in the design of BMPs for both quantity and quality issues. During snowmelt, the occurrence of large volumes of melt water together with large pollutant loads coincides with frozen grounds and reduced infiltration capacity, frozen pipes and inlets/outlets, ice-layers, low biological activity and changed water chemistry (Oberts, 2003). Due to the described cold climate conditions, the effectiveness of BMPs is often lowered and needs special considerations concerning design criteria, performance, maintenance and operation. ...
... Alternative LID designs are commonly subjected to increased scrutiny, especially with respect to cold climate performance while the same concerns for conventional and some manufactured treatment systems are more apt to be overlooked. A wide range of research exists for sand filters Roseen et al. 2006;Urbonas et al. 1996;Veenhuis et al. 1989;Wanielista 1981and bioretention systems Davis et al. 1998, 2003Dietz 2007;Dietz and Clausen 2007;Hsieh and Davis 2005;Hunt et al. 2006;Roseen et al. 2006; Winogradoff 2001. Less research is available on the use of subsurface gravel wetlands for storm water Egan et al. 1995;Reuter et al. 1992;Roseen et al. 2006. ...
Article
Full-text available
Lack of widespread adoption of low-impact development LID designs in northern climates is in large part due to concerns about poor winter performance relating to 1 frozen filter media; and 2 dormant biological functions. An examination of six varied LID designs, in contrast with conventional best-management practices BMPs and manufactured systems illustrated that seasonal functionality was evident for many systems; however, the LID designs were consistently top storm water management performers. The designs were tested and monitored for cold climate performance from 2004-2006 to assess: filter media frost penetration, hydraulic efficiency, and seasonal variations of contaminant removal efficiency. LID systems evaluated included: two types of bioretention systems, a surface sand filter, a subsurface gravel wetland, a street tree, and porous asphalt. The LID performance data were contrasted with conventional structural BMPs swales, retention pond and some select manufactured storm-water systems hydrodynamic separators; 3 a filtration system, and a subsurface infiltration system. Seasonal performance evaluations indicate that LID filtration designs differ minimally from summer to winter, while smaller systems dependent largely on particle settling time demonstrated a marked winter performance decline.
... In the lake water samples gathered on 2/22/2007 and 11/15/2007 the molar ratio of Cl − to Na + was 1.13:1. It is speculated that the molar relationship is not exactly 1:1 because Na + ions are known to adsorb onto particles whereas Cl − is not (Lofgren 2001;Norrstrom and Bergstedt, 2001;Oberts, 2003). The molar ratio is, however close enough to 1: 1 to confirm that NaCl is the likely source of elevated Na + and Cl − concentrations in the TCMA lakes. ...
Article
Over 317,000 tonnes of road salt (NaCl) are applied annually for road deicing in the Twin Cities Metropolitan Area (TCMA) of Minnesota. Although road salt is applied to increase driving safety, this practice influences environmental water quality. Thirteen lakes in the TCMA were studied over 46 months to determine if and how they respond to the seasonal applications of road salt. Sodium and chloride concentrations in these lakes were 10 and 25 times higher, respectively, than in other non-urban lakes in the region. Seasonal salinity/chloride cycles in the lakes were correlated with road salt applications: High concentrations in the winter and spring, especially near the bottom of the lakes, were followed by lower concentrations in the summer and fall due to flushing of the lakes by rainfall runoff. The seasonal salt storage/flushing rates for individual lakes were derived from volume-weighted average chloride concentration time series. The rate ranged from 9 to 55% of a lake's minimum salt content. In some of the lakes studied salt concentrations were high enough to stop spring turnover preventing oxygen from reaching the benthic sediments. Concentrations above the sediments were also high enough to induce convective mixing of the saline water into the sediment pore water. A regional analysis of historical water quality records of 38 lakes in the TCMA showed increases in lake salinity from 1984 to 2005 that were highly correlated with the amount of rock salt purchased by the State of Minnesota. Chloride concentrations in individual lakes were positively correlated with the percent of impervious surfaces in the watershed and inversely with lake volume. Taken together, the results show a continuing degradation of the water quality of urban lakes due to application of NaCl in their watersheds.
... Th e importance of the snowfall at the beginning stage of snowmelt runoff is consistent with previous studies. For example, Oberts (2003) reported that during the snowmelt runoff , the concentration of solute decreased with the progress of snowmelt. Han et al. (2010) also concluded that the fi rst fl ush of snowmelt runoff was considered the most critical event in nutrient export. ...
Article
Full-text available
A long-term, field-scale study in southern Manitoba, Canada, was used to identify the critical factors controlling yearly transport of nitrogen (N) and phosphorus (P) by snowmelt runoff. Flow monitoring and water sampling for total and dissolved N and P were performed at the edge of field. The flow-weighted mean concentrations and loads of N and P for the early (the first half of yearly total volume of snowmelt runoff), late (the second half of yearly total volume of snowmelt runoff), and yearly snowmelt runoff were calculated as response variables. A data set of management practices, weather variables, and hydrologic variables was generated and used as predictor variables. Partial least squares regression analysis indicated that critical factors affecting the water chemistry of snowmelt runoff depended on the water quality variable and stage of runoff. Management practices within each year, such as nitrogen application rate, number of tillage passes, and residue burial ratio, were critical factors for flow-weighted mean concentration of N, but not for P concentration or nutrient loads. However, the most important factors controlling nutrient concentrations and loads were those related to the volume of runoff, including snow water equivalent, flow rate, and runoff duration. The critical factors identified for field-scale yearly snowmelt losses provide the basis for modeling of nutrient losses in southern Manitoba and potentially throughout areas with similar climate in the northern Great Plains region, and will aid in the design of effective practices to reduce agricultural nonpoint nutrient pollution in downstream waters.
... One of the primary tools used in decentralized urban stormwater management is routing runoff to bioretention systems integrated into the landscape (Oberts, 2003). ...
Article
One of the primary tools used in decentralized urban stormwater management is routing runoff to bioretention systems integrated into the landscape (Oberts, 2003). To date, observation suggests that bioretention systems continue to infiltrate during the winter to varying degrees; however, little field research is currently available to quantify their snowmelt infiltration performance. A three-year study funded by the Water Environment Research Foundation (WERF) field-tested the cold climate hydrologic performance of four existing bioretention cells in the greater Twin Cities, MN, region. Sites were selected based on varying design applications including parking lot runoff, street runoff in a residential setting and a commercial application, in soils from sand and sandy loam to clay loam. The primary hydrologic test consisted of applying up to 6,000 gallons of water to a bioretention cell under various frost conditions. The synthetic snowmelt infiltration rates at the surface were measured as the pool receded while dynamic soil moisture readings tracked the subsurface water movement through the soil profile. Data on air, water and soil temperature, snow depth and frost penetration were collected on site. Measured responses reveal that these bioretention cells maintained hydrologic function in cold climates including many cases where rapid infiltration occurred. The primary study findings are that bioretention systems designed successfully for warm climate conditions will likely perform well in cold climate conditions and a well draining soil-type is the single most important design characteristic. The type of frost, rather than the presence or absence of frost, strongly influences bioretention performance, restricting infiltration under concrete frost conditions and facilitating rapid infiltration under granular frost conditions. Under-drains affect both the range of infiltration rates and the overall function.
... Zhao and Gray (1999) modelled for different textures the water and heat transport taking into account phase changes in frozen soils. It is easily understood that winter strongly influences stormwater treatment in cold climate regions because of ice formation in treatment systems, reduced biological activity, increased water density and frozen soils (Oberts, 2003). Muthanna et al. (2007a) and Backstrom (2003) demonstrated that vegetated infiltration devices remove pollutants, especially those bound to particles, also during winter and can thus be used as storage facilities for polluted snow. ...
Article
Full-text available
In cold climate regions winter conditions significantly influence the performance of stormwater infiltration devices. Frozen soil and water storage by snow changes their operation. In this paper winter operation of a grassed infiltration swale was investigated using on-site and laboratory measurements. The field investigation of a grassed swale at a parking place in an Alpine region showed that the swale fulfilled its function properly. Although the top layer was frozen for some time, the storage capacity of the swale was sufficient to store the precipitation until the conditions improved. The soil attenuated the air temperature, at 20 cm below ground surface the soil was only frozen for one week. winter maintenance proved to be a problem, together with the snow from the parking place a lot of gravel and fine particles were deposited at one end of the swale. This decreased the hydraulic conductivity at that point significantly. The laboratory tests with soil columns showed an increase of flow time through the soil column with decreasing soil moisture content. For soil temperatures below 0 degrees C the hydraulic conductivity was reduced for increasing initial soil moisture contents. All in all the hydraulic conductivity was best around 0 degrees C for all soil water contents. However, also at minus 5 degrees C the coefficient of hydraulic conductivity was always at least above 10(-6) m/s, thus within the range of tolerated hydraulic conductivity specified in the national guidelines. Nevertheless, the handling of the soil was found to have high influence on the results. The results indicate that in the Alpine region infiltration swales operate sufficiently under winter conditions although with decreased performance.
... For example, the unexpectedly high Pb levels and their independence from other metals in H36% showcases the catchment-specific sources. The observed Pb load likely originated from old building structures, such as roofs and paints (Davis and Birch, 2010;De Silva et al., 2016), and the winter-time elevated levels are likely linked to rain-on-snow events, daytime roof heating, and short-term melting (Semadeni-Davies et al., 2001;Oberts, 2003). This cold season challenges the performance of green infrastructure solutions to remove metals from stormwater. ...
Article
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Urban hydrology is characterized by increased runoff and various pollutant sources. We studied the spatio-temporal patterns of stormwater metal (Al, V, Cr, Mn, Fe, Cu, Zn, and Pb) concentrations and loads in five urbanized and one rural catchment in Southern Finland. The two-year continuous monitoring revealed a non-linear seasonal relationship between catchment urban intensity and metal export. For runoff, seasonal variation decreased with increasing imperviousness. The most urbanized catchments experienced greatest temporal variation in metal concentrations: the annual Cu and Zn loads in most of the studied urbanized catchments were up to 86 times higher compared to the rural site, whereas Fe loads in the urbanized catchments were only circa 29% of the rural load. Total metal levels were highest in the winter, whereas the winter peak of dissolved metal concentrations was less pronounced. The collection of catchment characteristics explained well the total metal concentrations, whereas for the dissolved concentrations the explanatory power was weaker. Our catchment-scale analysis revealed a mosaic of mainly diffuse pollutant sources and calls for catchment-scale management designs. As urban metal export occurred across seasons, solutions that operate also in cold conditions are needed.
... Second, snow melting is an important factor of soil pollution in spring. Snow is a deposit medium with high sorption properties, and toxic substances accumulate in it during the winter (Coldsnow & Relyea, 2018;Oberts, 2003). This can lead to the higher spring phytotoxicity of urban soils (Bardina et al., 2017;Kostka et al., 2019;Šerá, 2017). ...
Article
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The aim of this study was to assess the ecological state of the soil of a megalopolis (St. Petersburg) located in the North-West of the Russian Federation using bioassay in order to create a set of the most sensitive biotests. For this, 4-year monitoring studies of the soil quality in different functional zones of the city were carried out using the bioassay, physicochemical, and chemical analyses. A set of express biotests that allow for an integral ecotoxicological assessment of urban soils was developed and tested for the first time. The developed block of biotests consists of test organisms that are representatives of the main levels of the trophic chain: higher plants (Triticum vulgare L.) for producers, hydrobionts (Paramecium caudatum) for consumers, and natural soil microbiocenosis for decomposers. All the test cultures revealed the toxicity of urban soils; they were characterized by different sensitivities to toxicants. Our result showed that a correct assessment of the ecological state of urban soils is possible on the basis of the combined use of eluate (water extract) and contact bioassays. Biotests make it possible to record negative phenomena in urban soils, which occur even under low human-induced loads. The research data confirm the necessity and effectiveness of the study of the soils’ state using a battery of bioassays for inclusion in the monitoring system of urban soils.
... Urbonas et al. 1996; Veenhuis et al. 1989; Wanielista 1981) and bioretention systems (Davis et al. 1998; Davis et al. 2003; Hsieh and Davis 2005; Hunt et al. 2006; Roseen et al. 2006; Winogradoff 2001). Far less research is available on the use of subsurface gravel wetlands for stormwater (Egan et al. 1995; Reuter et al. 1992; Roseen et al. 2006). Oberts (2003) characterized cold climate affects on BMPs and discusses the use of infiltration and filtration mechanisms for treatment of the first flush of meltwater as a viable stormwater management strategy. For manufactured stormwater devices, people are left largely to manufacturer claims for product efficiency. Some field assessments of hydrody ...
Conference Paper
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Between 2004 and 2006 a range of six Low Impact Development (LID) designs were tested and monitored over 11 storm events for cold climate performance including filter media frost penetration and resulting hydrographs, seasonal variations on contaminant removal efficiency, and attenuation of chloride pulses associated with melt events. LID systems evaluated include 2 types of bioretention systems, a surface sand filter, a gravel wetland, a tree filter, and porous asphalt. The LID performance data will be contrasted with conventional structural BMPs (swales, retention ponds), and some select manufactured stormwater systems. Winter monitoring includes both rainfall runoff data and diurnal melt events. Contaminant event mean concentration (EMC), and performance efficiency were evaluated for storms with varying rainfall-runoff characteristics. Runoff constituent analyses included total suspended solids (TSS), diesel range organics (DRO), nitrate (NO3), and zinc (Zn). Several water quality parameters (temperature, dissolved oxygen, pH, conductivity) were monitored as real-time data. Performance evaluations indicate that LID designs have a high level of functionality during winter months and that frozen filter media appears not be a concern. Trends in chloride attenuation are complex.
... Accumulation of heavy metals, organics, and inorganic compounds can be acute in urban snow runoff (Sansalone et al. 1996(Sansalone et al. , 2002Sansalone and Glenn 2002), leaving the need for effective winter storm-water management in northern climates. Low-impact development storm-water designs have been shown to be extremely effective at reducing contaminant loads from impervious surfaces (Dietz and Clausen 2008;Dietz 2007), in northern climates (Oberts 2003;Roseen et al. 2009), and for reducing peak flow, lag time, and runoff volume (Hood and Clausen 2007). Porous pavement usage in cold climates has been found to be more resistant to freezing than standard pavements largely because of its disconnection to subsurface moisture and because it thaws more rapidly as a result of the rapid infiltration of meltwater (Backstrom 2000). ...
Article
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This study examined the functionality of a porous pavement storm-water management system in coastal New Hampshire where 6 months of subfreezing temperatures typically occur. The usage of porous pavements for storm-water management in northern climates has many challenges, most of which relate to the extreme cold and significant frost penetration into the porous media. The porous pavement system was monitored for hydraulic and water-quality performance from 2004 to 2008. The use of porous pavements for parking lots for new and redevelopment projects are one watershed-based strategy that can both mitigate impacts for new development and reverse impacts in areas with redevelopment. Surface infiltration capacity and frost penetration were measured monthly to assess winter performance. Because of the well-drained nature of the porous pavement and reservoir base, issues related to frozen media were minimized. Significant frost penetration was observed up to depths of 71 cm without declines in hydrologic performance or observable frost heave. No consistent statistical difference was observed for seasonal hydrologic performance with mean infiltration capacity ranging from 1,490 to 2,690-cm/h. Adverse freeze-thaw effects, such as heaving, were not observed, and for that reason, the life span is expected to exceed that of typical pavement applications in northern climates. Observed hydrologic response resembled shallow depth groundwater drainage, as is the goal for low-impact development designs. Peak flows were reduced by 90% to 0.58-m3/s/km2±0.74 in comparison with standard impervious cover=5.5-m3/s/km2±7.7. There was exceptional water-quality treatment performance for petroleum hydrocarbons, zinc, and total suspended solids with nearly every value below detection limits. Only moderate removal was observed for phosphorous, and treatment for nitrate (NO3) was negative.
... Nicht nur das: In den genannten Staaten wird darüberhinaus aktiv geforscht und untersucht, wie Räumschnee auf umweltschonendere Weise entsorgt werden kann, und es wurden dazu mehrere brauchbare Alternativen vorgeschlagen (siehe z.B. MarsalekOberts 2003;Viklander et al. 2003; Wheaton und Rice 2003). Der wahrscheinlich brauchbarste Vorschlag geht von der Lagerung großer Räumschneemengen auf eigens dafür vorbereiteten Arealen aus, auf denen der Räumschnee im Frühjahr unter kontrollierten Bedingungen abschmelzen kann. ...
Technical Report
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Zusammenfassung Der Anlass für das vorliegende Gutachten ("Ökotoxikologisches Gutachten zum Risikopotential der Räumschnee-Entsorgung in die Kitzbüheler Ache und Großache"), das im Auftrag des Fischereiverbandes des Bezirkes Kitzbühel entstand, liegt in der während der vergangenen Wintermonate wiederholt erfolgten Räumschnee-Entsorgung in die Kitzbüheler Ache und Großache, sowie in deren Nebenflüsse. Beide Bäche liegen in der Forellen-und Äschenregion und stellen wichtige Fischgewässer dar. Sie weisen eine reichhaltige Fisch-und Invertebratenfauna auf, deren Bestände aber bereits rückläüfig und jedenfalls zusehends bedroht sind. Insbesondere die kleineren Zuflüsse der Kitzbüheler Ache und der Großache sind darüberhinaus durch die Räumschnee-Einbringung auch in ihrer ökologischen Vielfalt und landschaftlichen Qualität existentiell gefährdet. Das vorliegende Gutachten zeigt auf, dass Altschnee aufgrund seiner physikalisch-chemischen Beschaffenheit an exponierten, urbanen Verkehrsflächen in besonds hohem Maß Schadstoffe und Schadstoff-beladene Feinpartikel anreichert. Durch Einschüttung von Schadstoff-belastetem Räumschnee werden den betroffenen Fließgewässern in wiederholt-abrupten Schüben und in unkontrolliertem Ausmaß Mischungen von Streusplitt, Schad-und Schwebstoffen zugeführt, die für sich allein genommen schon zu akut lethalen Effekten bei Fischen führen können. Verschärft wird die prekäre Situaton aber noch durch die Tatsache, dass die Räumschnee-Entsorgung mit dem winterlichen Niedrigstwasseerstand und mit der Laichzeit der Leitfischarten der Salmonidengewässer (Bach-und Regenbogenforelle) zusammenfällt. Dies gefährdet unmittelbar die jährlich im Spätwinter aufkommende Fischbrut. Besonders belastend wirkt sich jedoch die Tatsache aus, dass es durch die Räumschnee-Einschüttung auch jedes Mal zu einer plötzlichen, innerhalb von Sekunden eintretenden Veränderung der physikalischen Umweltbedingungen in den Fließgewässern kommt, was für die aquatische Lebewelt an sich schon eine enorme Stressbelastung darstellt. In Kombination mit der zu erwartenden akuten Schadstoff-Einwirkung führen diese multiplen Stressfaktoren nicht nur zu gelegentlich lethalen Effekten bei Fischeiern, Larven und Jungfischen, sondern vielfach zu einem Totalausfall der Brut und damit zu einer existentiellen Bedrohung der bereits vor-belasteten und ausgedünnten Bestände. Dies um so mehr, als durch verbürgte Beobachtungen durch Fischerei-Sachverständige nachgewiesen ist, dass zahlreiche Standorte der Räumschnee-Einbringung unmittelbar oberhalb von Fischlaichplätzen liegen. Bäche und Flüsse sind die Lebensadern unserer Landschaften, auch wenn dies im alltäglichen Betrieb vielen Akteuren nicht bewusst sein mag. Keinesfalls sollten Bemühungen zur 3 Renaturierung der Fließgewässer, die lobenswerterweise im Bezirk Kitzbühel bereits begonnen wurden, durch die enorme Über-Belastung, wie sie die Räumschnee-Einbringung darstellt, wieder zunichte gemacht werden. Die Erhaltung der ökologischen Vielfalt und Qualität der Fließgewässer im Bezirk Kitzbühel muss objektiv gesehen aber wohl auch im Interesse der Erholungs-und Tourismuswirtschaft des Bezirkes Kitzbühel liegen. Es sei daran erinnert, dass die Konkurrenz um Gäste und Besucher für hochwertige Landschafts-und Erholungsräume weltweit mit jedem Tag im Steigen begriffen ist. Der Gutachter empfiehlt daher, die Räumschnee-Einschüttung in die Fließgewässer des Kitzbüheler Raumes im Interesse der ökologischen Vielfalt und Qualität des Landschaftsraumes, aber auch im Interesse aller beteiligten Akteure in Zukunft zu unterlassen.
... This unexpected response was attributable to successful storage of soil on catchment slopes during summer, followed by remobilization during spring melt, during periods of low vegetation cover. This is consistent with findings from other studies [Oberts, 2003] which confirm that low biological activity and frozen ground make the spring melt period one of the most difficult to manage. On an annual timescale, the effects of soil remobilization in the Whites rendered the BMP ineffective. ...
Article
Uncertainty surrounding future climate makes it difficult to have confidence that current nutrient management strategies will remain effective. This study used monitoring and modelling to assess current effectiveness (% phosphorus reduction), and resilience (defined as continued effectiveness under a changing climate) of best management practices (BMPs) within 5 catchments of the Lake Simcoe watershed, Ontario. The model INCA-P was used, and monitoring data used to calibrate and validate a series of management scenarios. To assess current BMP effectiveness, models were run over a baseline period 1985-2014 with and without management scenarios. Climate simulations were run (2070-2099), and BMP resilience calculated as the % change in effectiveness between the baseline and future period. Results demonstrated that livestock removal from water courses was the most effective BMP, while manure storage adjustments were the least. Effectiveness varied between catchments, influenced by the dominant hydrological and nutrient transport pathways. Resilience of individual BMPs was associated with catchment sensitivity to climate change. BMPs were most resilient in catchments with high soil water storage capacity, and small projected changes in frozen-water availability and in soil moisture deficits. Conversely, BMPs were less resilient in catchments with larger changes in spring melt magnitude and in overland flow proportions. Results indicated that BMPs implemented are not always those most suited to catchment flow pathways, and a more site-specific approach would enhance prospects for maintaining P reduction targets. Furthermore, BMP resilience to climate change can be predicted from catchment physical properties and present day hydrochemical sensitivity to climate forcing.
... Cependant d'autres auteurs tels que Bäckström et al. (2003) ont montré une influence de la période hivernale, mais pas de l'utilisation des fondants routiers directement. L'augmentation de la concentration en ETM et en MES peut être influencée par différents paramètres : les fondants routiers, la présence d'un manteau neigeux compact, l'utilisation de pneus neige, le temps froid et humide qui favorise la corrosion (Oberts, 2003 ;Bäckström et al., 2004 ;Hallberg et al., 2007 ;Helmreich et al., 2010). ...
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En conditions hivernales rigoureuses, l'application des fondants routiers (principalement du chlorure de sodium - NaCl) permet d'assurer la sécurité des usagers de réseaux. Toutefois, son utilisation généralisée entraîne des risques de contamination des écosystèmes aquatiques et terrestres. En milieu routier, le Na+ et Cl- sont transportés par les eaux de ruissellement vers des ouvrages de traitement tels que les bassins de rétention-décantation. Or, ces bassins n'ont pas la capacité de traiter efficacement cet apport de fondants sous forme dissoute. L'objectif de cette thèse est d'étudier le transfert de ces fondants au sein du système routier et de déterminer leur rôle dans la libération des polluants en période hivernale. Les caractéristiques du bassin situé à Azerailles (Lorraine, France) sur une route nationale moyennement fréquentée ont été étudiées, ainsi que les conditions météorologiques, les salages, la composition des matières en suspension (MES) et la concentration en éléments traces métalliques (ETM). Les résultats ont permis de montrer que entre 50 et 90 % du Cl- ont été collectés par le bassin. Il joue un rôle de tampon qui permet une libération du Cl- dilué durant la période de ruissellement suivant la période de salage. La présence de NaCl dans les eaux a joué un rôle sur la diminution de la qualité des matières en suspension, en mettant en évidence la présence de polluants organiques en période de salage. Elle entraîne également une modification de la chimie des eaux et une augmentation des polluants métalliques (zinc).
... Also, associated low temperatures change pollutant chemistry and concentrations. Urban snowmelt often has high soluble contaminant concentrations [9]. Snowmelt has significantly higher sediment loads and a stronger correlation between TSS, sediment size, and metal concentration than rain runoff [10]. ...
Article
Bioretention is a popular best management practice of low impact development that effectively restores urban hydrologic characteristics to those of predevelopment and improves water quality prior to conveyance to surface waters. This is achieved by utilizing an engineered system containing a surface layer of mulch, a thick soil media often amended with a variety of materials to improve water quality, a variety of vegetation, and underdrains, depending on the surrounding soil characteristics. Bioretention systems have been studied quite extensively for warm climate applications, but data strongly supporting their long-term efficacy and application in cold climates is sparse. Although it is apparent that bioretention is an effective stormwater management system, its design in cold climate needs further research. Existing cold climate research has shown that coarser media is required to prevent concrete frost from forming. For spring, summer and fall seasons, if sufficient permeability exists to drain the system prior to freezing, peak flow and volume reduction can be maintained. Additionally, contaminants that are removed via filtration are also not impacted by cold climates. In contrary, dissolved contaminants, nutrients, and organics are significantly more variable in their ability to be removed or degraded via bioretention in colder temperatures.Winter road maintenance salts have been shown to negatively impact the removal of some contaminants and positively impact others, while their effects on properly selected vegetation or bacteria health are also not well understood. Research in these water quality aspects has been inconsistent and therefore requires further study.
... During winter in cold or temperate climates, pollutant concentrations are particularly high, and de-icing salt often affects metal partitioning towards the dissolved phase (Marsalek et al. 2003;Oberts 2003). The presence of salt has been shown to substantially influence the ability of stormwater biofilters to remove metals. ...
Chapter
Metals were the first priority pollutants to be widely investigated in stormwater. In solid phase, they are often attached to very fine particles. The dissolved fraction creates considerable environmental problems as it is the most bioavailable fraction. Hence, removal of both fine and dissolved particles plays a major role in the treatment of polluted runoff. Ecotechnologies specifically designed to remove metals should be able to address different treatment mechanisms. However, the exhaustion of sorption capacity reduces the lifespan of treatment facilities. Additionally, metal concentrations fluctuate extremely—spatially, seasonally and over time—which poses another challenge for further increasing removal efficiencies. While soil- or sand-based systems should be designed in a way that the filter material can be exchanged, newer developments such as Floating Treatment Wetlands show promising removal capacities as the installations bind metals in sludge sediments, which can be removed from time to time. The different treatment mechanisms, aforementioned developments and techniques as well as their removal capacities will be discussed in this chapter.
... In the Twin Cities of Minnesota, an estimated 142,000 metric tons of Cl is applied each year, and urban aquifers have Cl concentrations as high as 2000 mg L −1 , where pre-settlement chloride concentrations were estimated at 3 mg L −1 (Novotny et al., 2009). Stormwater runoff from snowmelt and rain-onsnow events in cold climates not only delivers elevated pollutant loads but may be accompanied by frozen soils and low biological activity (Oberts, 2003). Green infrastructure designs for cold climate cities need to address signifi cant water quality challenges. ...
Article
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Cold climate cities with green infrastructure depend on soil bacteria to remove nutrients from road salt-enriched stormwater. Our research examined how bacterial communities in laboratory columns containing bioretention media responded to varying concentrations of salt exposure from artificial stormwater and the effect of bacteria and salt on column effluent concentrations. We used a factorial design with two bacteria treatments (sterile, nonsterile) and three salt concentrations (935, 315, and 80 ppm), including a deionized water control. Columns were repeatedly saturated with stormwater or deionized and then drained throughout 5 wk, with the last week of effluent analyzed for water chemistry. To examine bacterial communities, we extracted DNA from column bioretention media at time 0 and at week 5 and used molecular profiling techniques to examine bacterial community changes. We found that bacterial community taxa changed between time 0 and week 5 and that there was significant separation between taxa among salt treatments. Bacteria evenness was significantly affected by stormwater treatment, but there were no differences in bacterial richness or diversity. Soil bacteria and salt treatments had a significant effect on the effluent concentration of NO, PO, Cu, Pb, and Zn based on ANOVA tests. The presence of bacteria reduced effluent NO and Zn concentrations by as much as 150 and 25%, respectively, while having a mixed effect on effluent PO concentrations. Our results demonstrate how stormwater can affect bacterial communities and how the presence of soil bacteria improves pollutant removal by green infrastructure.
Article
This overview of research findings presented at the conference on urban drainage and highway runoff in cold climates starts with generation of urban runoff and snowmelt, followed by snowmelt and winter runoff quality, best management practices for urban snowmelt and winter runoff, and snow management in urban areas. Research on the urban hydrological cycle is lagging behind the needs in this field, particularly in terms of data availability. The current studies of winter urban runoff quality focus on road salts in the urban environment and their environmental effects. The needs for better source controls in salt applications, improved management of chloride-laden runoff, and selective adoption of environmentally safer alternative de-icers were reported. Adaptation of the conventional stormwater best management practices (BMPs) for winter operation remains a challenge. The first step in refining the existing BMPs for winter operation is to advance the understanding of their operation, as reported for some cases at the conference. Finally, snow management in urban areas may require local storage of fresh (unpolluted) snow and disposal of more polluted snow at central snow disposal sites.
Article
Pollution from nonpoint-source (NPS) nitrogen (N) and phosphorus (P) are the main causes of eutrophication in lotic, lentic and coastal systems. The climate of cold regions might play an important role in disturbing environmental behavior of NPS N and P, influencing simulation of watershed scale hydrologic and nonpoint-source pollution models. The losses of NPS N and P increase in regions of cold climate. In cold seasons, accumulations of N and P are accelerated in soil with increasing fine root and aboveground biomass mortality, decreasing plant nutrient uptake, as well as freezing soil. N and P transformation is disturbed by soil frost and snow. Moreover, factors such as physical disruption of soil aggregates, pollutant accumulation in snowpack, and snow melting can all increase the NPS N and P losses to the waterbody. Therefore, NPS N and P in first flush are more serious in cold climate. All these effects, especially frozen soil and snowpack, make great challenges to watershed scale hydrologic and nonpoint-source pollution models simulation in cold climate. Model improvements of snowmelt runoff, nutrient losses in frozen soil, as well as N and P behavior have been initiated and will be continued to evaluate in terms of their performances and suitability with different scale, hydrologic and geologic conditions in the future.
Article
Predicting the environmental effects of de-icing salt requires knowledge of the pathways taken by salt from on-road application through spread to the surroundings to deposition and fate in the roadside environment. This study described differences in chloride deposition and distribution in soil with increasing distance from the road by means of field observations and modelling. The dynamic modelling approach successfully represented the spread of de-icing salt from road to surroundings, deposition in the roadside environment and the subsequent infiltration into roadside soil. The general decrease in soil chloride content with distance from the road was described by differences in salt deposition, soil physical properties, vegetation properties and snow characteristics. The uncertainty in model predictions was highest in areas close to the road due to a complex combination of high salt deposition, snow-ploughed masses and road runoff. The exponential decline in salt deposition with distance from the road could not be justified close to the road. Different types of field investigations were applied in a calibration procedure to establish reasonable ranges for the most influential model parameters. Measured electrical resistivity reflected well the changes in simulated chloride content in soil during winter and spring when chloride concentrations were high. However, during summer or periods with low chloride concentrations the measured resistivity was substantially lower than simulated values, as it reflected the total contamination level in soil.
Article
This paper evaluates the performance and winter hydrology of two small-scale rain gardens in a cold climate coastal area in Trondheim, Norway. One rain garden received runoff from a small residential watershed over a 20 month study period while the second rain garden with a shorter study period of 7 months was used as a control. The objective of the study was to investigate the extent to which cold climatic conditions would influence the hydrology and performance of the rain gardens. The hydraulic detention, storm lag time and peak flow reduction were measured and compared seasonally. No significant difference between seasonal lag time could be found, but there was a clear decreasing trend in lag time between rain, rain-on-snow and snowmelt. The average peak flow reduction for 44 storms in the study period was 42% compared to 27% for the winter seasons, indicating that the performance of the rain garden is reduced in the cold season (below 0 °C). The average hydraulic detention time for the rain garden was 0·84 ( ± 0·73) with runoff inflow and 1·91 ( ± 3·1) with only precipitation. A strong positive correlation was found between the time since the last wetting event and lag time, and between air temperature and hydraulic detention. This indicates that the time between events and seasonal air temperatures are key parameters in the hydraulic performance of cold climate rain gardens. The rain gardens were not used for snow storage areas, and a volume requirement for this was not evaluated in the study. Copyright © 2007 John Wiley & Sons, Ltd.
Chapter
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The current literature compartmentalizes the complex issue of water and wastewater into its discrete components; technology, planning, policy, construction, economics, etc. Considered from the perspective of sustainability, however, water in the urban environment must be approached as a single resource that can be continuously reused and recycled. This book will be the first to capture all of the current work on this idea in a single, integrated, plan for designing the water-centric cities of the future. From new construction to the retrofitting of existing systems, this book presents the case for a new urban relationship to water, one with a more sustainable connection to the environment and the hydrological cycle. Through case studies of successfully planned and built systems around the world, the book will educate the reader about the need for a new approach to urban water management, and make the case that these changes are not only possible but imperative.
Article
A high-precision low-flow measurement device that used two different orifices valid over a wide range of small flows measured flow to a rain garden. The design of the device is presented. Direct measurement of the roof runoff with this device was compared with inflow estimates derived from roof area and rainfall data from eight storms. The two methods agree on total inflow volume, although the measurement device captured inflow transients that were not observed in the roof-rainfall estimate. The rainfall-roof estimated inflow data varies in inflow peak time and inflow peak flow rate when compared with the high-resolution monitored inflow data. The inflow measurements were used to assess the infiltration performance of a rain garden in urban Kansas City.
Article
Temporal trends in stormwater pond sediment quality were evaluated by conducting field sediment surveys in 1998 and 2006. A sediment removal process in 2006 was also assessed. Results show that, for both years, the sediment closest to the inlet had the lowest concentrations of metals. The results from 1998 showed no significant differences in sediment heavy metal concentrations depth while the results from 2006 showed a decreasing trend with depth. A significant difference between the two years could be seen for Cr, Cu, and Pb. The water phase in the pond showed a difference before and after the removal of sediment. The water samples after emptying showed higher concentrations of metals as a result of disturbing and re-suspending the bottom sediment. No significant difference could be found in the samples taken from the bottom sediment before the removal of the sediment and from the sediment pile formed during the removal process. The total heavy metal concentration in water exceeded the threshold limits for the selected quality guidelines and, according to soil quality guidelines, the sediment would be classified moderately serious to serious.
Article
The porous matrix and long residence time of snow in traffic corridors can result in the accretion of particulate matter (PM) and metals. This temporary repository contributes PM-based and dissolved metals to surrounding environs during snowmelt. This study focused on distribution and settling of PM-based metals (Al, As, Cd, Cr, Cu, Fe, Pb, and Zn) in snow. Snow was sampled from six sites during four winter seasons. PM-based metals are examined herein as a function of PM granulometry, specifically particle-size distributions (PSDs) and PM surface area. Cumulative metal mass distributions across each PSD are modeled as gamma functions. Results indicate Al (15 g/kg) and Fe (4.2 g/kg) are the highest PM-based concentrations; Cd (0.18 mg/kg) and As (4.9 mg/kg) are the lowest. The PM size (d50 m) associated with the median metal mass ranges from 179 to 542 μm. The constitutive gamma results are integrated with Hazen's settling algorithm to model PM-bound metal separation for a sedimentation basin at a local snow storage site. Flows are modeled in the storm water management model (SWMM) from snowmelt and historical rainfall time series. Results indicate that Type I sedimentation is capable of separating the sediment fraction (>75 μm) and majority of metal mass. While the basin is effective at separation of coarser PM-based metals, additional practices such as pavement and drainage appurtenance cleaning, as well as adsorptive-filtration can further manage suspended PM and metals, as well as dissolved metals.
Chapter
This chapter presents information on strategies used to reduce the impacts of snow and ice control materials once they are introduced from the roadway into the surrounding environment. Commonly used techniques consist of the implementation of structural Best Management Practices (BMPs), which comprise reactive measures implemented along roadsides or near sensitive water sources to capture abrasives and treat deicer‐laden stormwater runoff. Due to the highly mobile nature of chlorides, increased chloride concentrations in the environment associated with roadway deicers pose a significant environmental concern and the use of traditional BMPs often fails to be effective in managing chlorides. This chapter provides an overview of using stormwater structural BMPs for management of suspended solids and chlorides, followed by a summary of criteria for BMP selection and alternative approaches to chloride removal. Subsequently, methods for cleanup and recycling of winter maintenance abrasives are discussed, followed by methods for recycling of salt brine.
Article
A critical review of the literature and practice indicates that design storm events, which have been used in specific fields of Canadian and US engineering practice for more than 100 years, can be ascribed to six basic attributes: (a) design return period, (b) storm duration, (c) intensity–duration–frequency (idf) relations (representing a summary of historical rainfall data, with some extrapolation for longer return periods), (d) temporal distribution (design hyetograph), (e) areal reduction factor, and (f) antecedent moisture conditions. Concerns about climate change (or variability) and the need to adapt to the associated climatic conditions prompted many agencies, and particularly municipalities, to revisit the design storm event issue, particularly in connection with drainage design. It would appear that this analysis has mostly focused on a single property of design storms — idf relations and projected increases in rainfall intensities. The review concludes that the design practice would be well served by adopting a comprehensive approach considering all design storm event characteristics and their sensitivity to climate change and inherent uncertainties in the existing idf relations as well as hydraulic design of sewer networks.
Article
Stormwater biofilters are used to treat stormwater runoff. In countries with cold winter climates, biofilters are subject to low temperatures which, in some cases, are combined with potentially high salt concentrations from road de-icing, potentially affecting the biofilter's performance. Since stormwater biofilters have been developed without consideration of their critical winter use, a laboratory study was carried out to evaluate the performance of stormwater biofilters subjected to low and high temperatures, with and without salt. Both factors and their interaction had a significant effect on outflow concentrations and removal percentages. Salt had a negative impact on outflow concentrations, causing lower removal percentages for (especially dissolved) metals, this impact being most pronounced for Cu and Pb. The unrealistic combination of salt with high temperature seemed to further amplify the negative impacts of salt despite the fact that temperature alone did not cause significant differences in outflow concentrations and removal percentages. Still, biofilters showed the ability to treat stormwater efficiently under the simulated winter conditions; outflow concentrations for total metals as a minimum met the class 4 threshold value defined in the Swedish freshwater quality guidelines, while inflow concentrations clearly exceeded the threshold value for class 5. The relatively coarse filter material (which is recommended to facilitate infiltration during winter) did not seem to exacerbate biofilter performance.
Thesis
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In recent decades, more than 90 percent of urban growth in the United States has taken place in the suburbs. The phenomenon, referred to as urban sprawl, has led to long-term degradation of environmental quality. Best Management Practices (BMPs) serve as novel effective technologies to reduce the movement of pollutants from land into surface or ground waters, in order to achieve water quality protection within natural and economic limitations. Four types of BMPs are discussed in this study—Pond, Wetland, Infiltration, and Filtering Systems. Each has different installation requirements, costs, and pollutant removal efficiency. The purpose of this research is to find out the minimum-cost combinations of these four technologies, with a focus on total suspended sediments (TSS), in order to achieve TMDL (Total Maximum Daily Loads) and EQS (Environmental Quality) standards. The methodology uses three major models: Spatial Model, Watershed Model, and Economic Model. These models provide suitability analyses for potential residential developments and BMP technology installations, stormwater and pollutant simulations, and minimum cost optimization procedure. The results of this research will provide a practical reference for decision making about the balance between the urban development and environment protection. It can further provide EPA with economic assessment information regarding existing TMDL and EQS standards.
Article
Stratification is one of the fundamental physical processes that may have a significant impact on water quality in stormwater wet ponds. However, the role of thermal and chemical stratifications in governing water quality processes is not fully understood. This is in part due to the lack of detailed field measurements of sufficient governing parameters over time periods that span a wide range of environmental conditions. To fill this gap, a comprehensive 2-year field program was undertaken in two stormwater wet ponds in Calgary, Alberta, Canada, during the ice-free season from May to November in 2018 and 2019. At different locations in each pond, thermal and chemical stratifications were observed, thermocline depth and strength were determined, and continuous water velocity profiles were measured. In addition, the effect of local weather conditions on stratification, thermocline, and hydrodynamics was investigated. The results showed that the ponds had vertical water temperature differences >1 °C for 99% of the time, May to August. In addition, salt-laden inflows from road deicing salts led to strong chemical stratification up to five times stronger in the sediment forebays than in the main cells in spring. Wind-induced surface currents were insignificant, scaling at 0.3% of the wind speed with negligible impact on vertical mixing in the ponds. Our results demonstrate that the ponds' strong and prolonged stratification decreased pollutant retention capacity and caused the water at depth to become anoxic, degrading the quality of the water discharged downstream. Hence, additional consideration of stratification is required when designing new stormwater ponds.
Article
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During the snowmelt period of 1967, snowmelt runoff from three pastured plots was measured as it moved to the stream channel over the ground surface, through the topsoil, and through the phreatic zone. Because of the presence of a thin layer of concrete frost in the normally porous topsoil, the infiltration capacity of the soil was reduced to a very low value. Almost one half of the meltwater left the plots as overland flow. Discharge rates, total volumes, and timing of this portion of the runoff were strongly controlled by incoming shortwave radiation. The response of subsurface flow to melting was heavily damped by storage and transmission of water in the soil. Combined daily hydrographs of runoff were dominated by overland flow. Comparison of the timing of such hydrographs with concurrent stream channel hydrographs from basins of the Sleepers River Experimental Watershed suggests that overland flow was a major control of the diurnal fluctuations of streamflow. Previous studies in the same area have demonstrated that much of the overland flow contributing to the responsive stream hydrographs of these basins originates on saturated areas of the watershed.
Article
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Snowmelt and runoff in urban areas in Luleå, north Sweden, are discussed and compared with rural conditions. The uneven snow distribution in cities is quantified. Energy fluxes at the snow surface in different environments are estimated. It is shown that, mainly because of increased absorbed radiative energy in the snow, the daily melt is about 10 mm higher in the city than in rural environments. In the course of prolonged snowmelt, the infiltration capacity of most soils in urban areas becomes so reduced that melt-induced peak flows from grassed and gravelled surfaces are similar to those from asphalted surfaces. When rain falls on snow, overland flow may take place from the entire area of a basin.
Article
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Two procedures to estimate the area-averaged snowmelt and meltwater outflow from a snowpack were compared for a river basin in the south part of European Russia. Both methods are based on the same model of melting snow but use two different methods for computing the snowmelt rate at the surface of the snowpack, the degree-day method and the Kuzmin method. For averaging, the spatial change in the meteorological inputs and the statistical distribution of the premelting snow water equivalent before melt are taken into account. The calculated basin-averaged meltwater outflow is checked against the snowmelt input obtained from the measured runoff hydrograph by solving the inverse problem for a runoff generation model. It also gives opportunities to calibrate the basin-averaged degree-day factor, coefficients of the heat component dependences, or dependences for parameters of spatial statistical distribution of snow characteristics. The procedure based on the Kuzmin method gave better results than that based on the degree-day method, both in the case of a priori assigned parameters and in the case of parameter calibration.
Article
Effective treatment of stormwater by laboratory-scale biofilters has demonstrated that these simple filters may be used to remove dissolved metals and sediment-adsorbed metals found in stormwater runoff. Laboratory testing indicated that even biofilm just 3 days old provided suspended solids and heavy metals removals in excess of 90%. A filter operated for 9 weeks retained its treatment efficiency and removed more than 90% of total Cu and Zn. Field-scale testing is recommended.
Book
Stormwater management has become an increasingly integral component of management of non-point source pollution of water resources. The Municipality of Anchorage, Alaska, has developed design criteria for stormwater treatment using sedimentation basins. The criteria were developed by collaboration among State and local water quality agency officials and the professional design community. Several such facilities have recently been constructed. Performance and cost data are presented from Anchorage experience.
Article
In order to investigate the concentration levels and chemodynamic behaviour of organic micropollutants and heavy metals in snowmelt runoff from urban sealed surfaces, meltwater was sampled from one street and four different roof catchments. Apart from peak concentrations of suspended solids during short intense street runoff from rain, concentrations of suspended solids in snowmelt runoff are two to fivefold higher than in rain runoff. However, the specific metal concentrations in suspended solids of snowmelt (except Zn) are lower than in suspended solids of rainwater runoff. This partly compensates the higher concentration of suspended solids. There are no distinct differences in concentrations of heavy metals between rain and meltwater runoff with the exception of dissolved Cd; its concentrations are increased when high concentrations of macro ions are present. We explain high concentrations of PAH with a molecular weight of 202 or less in snowmelt with longer equilibration times available during melting than during rain runoff. An enhancement of solubility by DOC seems to be likely. The physical and chemical properties of various roof surfaces greatly influence the temporal variation of PAH concentrations during snowmelt runoff.
Article
The winter operation of an on-stream stormwater management pond, located in Kingston, Ontario, Canada, was studied with respect to ice cover formation and breakup, density stratification, velocity field under the ice cover, and the risk of sediment washout. The pond freezes over in late November, with the ice thickness reaching up to 0.5 m. During the first half of the winter period, the ice thickness was well described by Stefan's formula with empirical coefficients appropriate for shallow water bodies. The pond was chemically stratified, with total dissolved solids concentrations up to 1200 mg · L-1 observed close to the bottom. The meromictic stability of this stratification was calculated as 882 g · cm · cm-2. Measurements of the velocity field under the ice cover indicated a flow pattern comprising a fast flow region, a small dead zone and a large recirculation zone to the north and south of the fast flow trajectory, respectively. Such a pattern agreed well with that simulated by a CFD model (PHOENICS(TM)). During a snowmelt event, the near-bottom velocities reached up to 0.05 m · s-1, but were not sufficient to scour the bottom sediment.
Article
Zinc and cadmium exhibit a preference for the dissolved phase whereas lead predominates in the suspended solid phase. Copper is distributed equally between both phases. The exchangeable fraction of the suspended solid phase exhibits unexpectedly high metal levels which may be easily released on contact with receiving waters and thus provide a major source of bioavailable metals. Both UK and Swedish catchments show consistently similar distributions of all four metals between the six experimentally determined fractions. The major differences are the higher lead concentrations found at the UL site and the considerably larger copper concentrations which are distinctive of the Swedish catchment. These higher copper levels accompany a free or weakly complexed copper contribution to the soluble phase which is absent within the UK catchment.
Article
Results suggest that roadside snowmelt may have profound effects on wetland plant community structure.-from Authors
Article
The radiation balance of urbanised catchments differs from their rural counterparts, with snowpacks experiencing either enhanced or decreased irradiance depending on snowpack location and condition. As snowmelt is largely driven by radiation inputs, changes to localised irradiance (and melt rates) have implications for urban runoff generation. Storm- and wastewater drainage systems in cold regions are currently dimensioned for rain according to practices developed for temperate climates. They are not designed to cope with wintry conditions, which can lead to surface flooding, hydraulic overloads and poor water quality at receiving waters.Net allwave radiation measurements over snow made at the Swedish city of Luleå during April 1997 and 1998 are presented. The 1997 measurements were made in the vicinity of a matt-black-painted metal building at Luleå University of Technology, whereas the 1998 measurements are from a specially constructed 3×6-m black plastic-clad wall built on an open field just outside the town. Black minimises multiple reflections between the snow and walls, while maximising absorption of shortwave radiation by walls. The data were compared to the outputs of an urban radiation model. The results show that urban structures significantly alter radiation over snow. The temperature of the south-facing walls translates to longwave enhancements in the order of 150 W m−2 for several metres from the walls on sunny days. Shaded snow near the north-facing wall showed a net allwave radiation loss of the same order of magnitude. Radiation inputs to snow are similar both to the north and south of walls when the sky is overcast. The need to include snowmelt energetics within design and management techniques is discussed in light of the results.
Article
This paper describes a case study on a new alternative drainage system for urban stormwater management, the so-called “Sandsli-system”. The aim of this study is to evaluate the Sandsli system and the effects of the solution on ground water conditions. The study is carried out in the Sandsli research catchment in Bergen, Norway. The idea behind the “Sandsli-system is not to mix the polluted and the clean stormwater combined with a source control for both stormwater quantity and quality. The clean stormwater is percolated as quickly as possible, while the polluted stormwater is collected and conducted to an appropriate site for disposal or treatment. The Sandsli-system was developed as an alternative drainage system to the conventional drainage system. The system has been functioning satisfactorily since 19S1 to date. The advantages of the use of the Sandsli-system is highlighted i.e. recharging the stormwater to the ground water. The Sandsli-system is appropriate to locations with climate and geology similar to that found in the coastal part of Norway
Article
In a naturally stratified snow cover the movement of meltwater into dry snow is complicated by the interaction of the wetting front with stratigraphic horizons. Field observations showed that when the wetting front reached premelt stratigraphic horizons, water ponded at the interface and then flow fingers developed and penetrated the lower stratum. The flux in these fingers, which was increased to about twice that of the surface flux, was used to feed water to the impeding horizons where it froze to form ice layers. These ice layers were the major source of latent heat released within the snow cover, and they were responsible for the warming of the snow and the underlying soil. These continuous ice layers grew only at stratigraphic boundaries. Because of this ice layer growth the wetting front advance was retarded, and the arrival of meltwater at the snow cover base was significantly delayed. Owing to a cold substrate the strong heat flux from the snow into the soil delays the warming of the snow cover and limits runoff after the snow is isothermal at 0°C by the refreezing of soil infiltration and the development of a basal ice layer.
Article
In Norway a considerable amount of pavement dust is produced during a year, particularly during the winter season when studded tyres are used on vehicles. The asphalt wear when using tyres is estimated to be 20–50 g/km/vehicle. This matter will partly be deposited on the road surface and partly be transported through the atmosphere to the surrounding area together with other motor traffic pollutants.A 3 year programme, sponsored by the Norwegian Road Directorate, was aimed also at characterizing the nature and the fate of the particulate matter from a highway. The characterization included studies on particle-size distribution, heavy metal concentration and contents of organic micropollutants, such as PAH.It was found that a major part of the pollutants from a highway was deposited 5–25 m from the road. Further it was observed that an essential part of the pollutants were “produced” through the snow accumulation period and released during the spring period. The period of snowmelt thus gave the most important effects on the surface water.The impact on lake water will be discussed in another paper.
Article
Snow studies have generally ignored the layered nature of snow covers. Having achieved a good understanding of the properties and processes in homogeneous snow, snow scientists should develop more insight into the evolution of the layers and their effects on overall snow response. Many of the outstanding problems in snow studies can only be solved by dealing with snow as a layered medium. The various mechanisms by which layers are generated, their effects, and some of the outstanding research problems are described here.
Article
Urban highways are a nonpoint source of metal elements and solids. These constituents are generated from traffic activities, pavement degradation, roadway maintenance, and atmospheric deposition. Pavement degradation and abrasion generates solids ranging in size from submicron particles to gravel-size aggregates. These constituents accumulate on the highway until they are transported from the pavement by traffic-induced turbulence or precipitation-runoff processes. Total metal elements and solids concentration are higher in snow washoff from urban highways than rainfall runoff. One reason is the snow washoff volume is less than the volume generated during a rainfall-runoff event. Another reason is that the residence time of a highway snowbank can range from hours to months depending on weather conditions. In addition, porous snow banks act as repositories that trap metals and solids. Metal elements and solids in urban highway winter snow and spring runoff at one highway site located along I-75 in Cincinnati, Ohio, are described and compared. Both snow and rainfall-runoff samples were fractionated into particulate-bound and dissolved metals. Solids characterization included dissolved, inorganic, and organic fractions. Results from snow samples taken at daily intervals from late January through mid-February 1995 indicate a significant increase in metal elements and solids accumulation for several days after two snow events. Results from runoff events in April 1995 indicate that the particulate-bound metal element washoff response was a function of rainfall intensity. In contrast, the dissolved response exhibited a dependence on the solubility of the metal element. Metal elements in rainfall-runoff were predominately dissolved as compared with more particulate-bound metals in snowfall.
Article
The influence of suburbanization upon runoff response to snowmelt and rain-on-snow inputs was examined for a small drainage basin in south-central Ontario. Modification of more than 50% of the basin area over a 14 year period led to a six-fold increase in the spring quickflow response ratio and an increase in the number of snowmelt events that generate appreciable quickflow. Anticipated changes in mean peak discharge, time of rise and quickflow response ratio did not emerge, and the influence of development upon these streamflow characteristics may have been overshadowed by annual changes in basin antecedent conditions. The distinction between hydrograph properties associated with snowmelt and rain-on-snow events has become more pronounced with suburbanization. Rain-on-snow generated higher maximum peak flows and lower average peak discharge per unit input compared with snowmelt, and these differences were accentuated by development of the basin. Rain-on-snow also produced more variable time of rise values, while the reduction in hydrograph recession coefficients that accompanied suburban development was most apparent for snowmelt events. The results suggest that suburbanization can have a subtle, yet real, influence upon basin runoff regime during spring snowmelt.
Article
The soluble impurities contained in a snow cover can be concentrated as much as five fold in the first fractions of snowmelt runoff. In addition, daily impurity surges are possible. Melt-freeze cycles concentrate the impurities in the lower portion of the snow cover, hence preparing the impurities for rapid removal. Environmental damage can occur due to the concentration and rapid release of atmospheric pollutants from the snow, especially in areas of ‘acid precipitation.’ The enrichment of the soluble impurities is explained and the results of laboratory experiments are given.
Article
In order to create a picture of the pollutant pathways for snow in urban areas, snow samples were collected in the city of Luleå, northern Sweden. Sampling sites were chosen in the city centre and in a housing area -three different sites in each area. Snow samples were collected during the whole winter of 1995. The results showed that the amounts of dissolved substances as percentages of the total amounts varied according to time, site and the type of substance. For the sites along the roadsides in the city centre, the amounts that were in solution were less than 1% of the lead, 2.5% of the phosphorus, 11% of the copper, and 18% of the zinc. For the site with no-traffic, the dissolved fractions were considerably higher.