Soil infiltration rate is a critical parameter in the design and evaluation of stormwater control facilities. The aim of this research was to evaluate selected infiltration models (Horton's, Kostiakov's, and Green-Ampt's) used to estimate final soil infiltration rate. Parameters of the models were estimated. The goodness of fit of the three equations for infiltration was tested using the root mean squared error (RMSE). Comparison of the field and predicted infiltration rate evaluated at each time interval indicated that the infiltration rate predicted by the Green-Ampt's and Horton's models were much closer to the measured data.

As climate change impacts accelerate, the characteristics (frequency, depth, intensity) of rainfall events are expected to become more intense and volatile. This study seeks to use historical data to examine stormwater control measures' (SCMs') ability to remove common pollutants during high intensity/depth storm events. This study examines bioretention and grassed swales, due to their prevalence within stormwater systems, varying susceptibility to scour, and depth of data available. Pollutant and rainfall depth data was extracted from the International Stormwater Best Management Practice (BMP) Database. Percent removal as a function of rainfall depth was then calculated. Findings suggest that assumed correlations between pollutants could be inaccurate under expected conditions. Findings also suggest that scour becomes concerning in SCMs that do not contain standing water or have a ponding depth to still water. Future work includes further analyzing assumed correlations between pollutants, expanding SCM types to further investigate effects of scour, and exploring percent removal as related to rainfall intensity.

Green infrastructure, specifically rain gardens, are increasingly used to manage urban runoff. Rain gardens vary in design and composition for a mix of aesthetic and functional reasons. Due to this variability, key performance drivers are hard to identify. This study evaluated 100 vegetated rain gardens in Lancaster, PA across seasons to determine which aspects of rain garden design impact performance. Gardens varied in size, slope, plant composition, planting density, and soil characteristics. There were significant seasonal differences in both performance (as measured by infiltration) and garden characteristics. Soil water content, compaction, and electrical conductivity along with plant species diversity significantly impacted infiltration. Certain plant species - Vernonia baldwinii (Ironweed), Nepeta cataria (Catmint), Itea virginica (Virginia Sweetspire), Rudbeckia sp. (Coneflower), and Eragrostis pectinacea (Purple Lovegrass) were present in high abundance and found to be drivers of performance. The results of this study demonstrate the diversity of factors that influence rain garden performance and highlight the importance of aligning soil and plant characteristics with specific outcome goals.

Green stormwater infrastructure (GSI) is adopted to reduce the impact of stormwater on urban flooding and water quality issues. This study assessed the performance of GSI, like bioretention basins, in accumulating metals. Twenty one GSI basins were considered for this study, which were located in New York and Pennsylvania, USA. Shallow (0-5 cm) soil samples were collected from each site at inlet, pool, and adjacent reference locations. The study analyzed 3 base cations (Ca, Mg, Na) and 6 metals (Cd, Cr, Cu, Ni, Pb, and Zn), some of which are toxic to ecosystem and human health. The accumulation of cations/metals at the inlet and pool differed between the selected basins. However, accumulation was consistently higher at the inlet or the pool of the basin as compared to the reference location. Contrary to prior research, this study did not find significant accumulation with age, suggesting that other factors such as site characteristics (e.g., loading rate) might be confounding. GSI basins that receive water only from parking lots or parking lots and building roofs combined showed higher metals and Na accumulation as compared to the basins that received stormwater only from building roofs. Cu, Mg and Zn accumulation showed a positive relationship with the organic matter content in soil, indicating likely sorption of metals on organic matter. Ca and Cu accumulation was greater in GSI basins with larger drainage areas. A negative relationship between Cu and Na implies that Na loading from de-icers may reduce Cu retention. Overall, the study found that the GSI basins are successfully accumulating metals and some base cations, with highest accumulation at the inlet. Additionally, this study provided evidence of GSI effectiveness in accumulating metals using a more cost efficient and time averaged approach compared to traditional means of stormwater inflow and outflow monitoring.

Green stormwater infrastructure (GSI) can provide multiple benefits in addition to stormwater management. However, there is a need to improve GSI siting to ensure these benefits are realized. We present a planning algorithm that hones in on ‘sweet spots’ of GSI implementation that are hydrologically optimal, feasible, and provide more equitable access to the benefits of GSI. We apply this approach in Lancaster, a city in Pennsylvania, US, with multiple stormwater-related challenges. To identify sweet spots, we first leveraged available spatial data to derive maps of five key criteria, including hydrology, vegetation, property ownership, sewer system type, and social vulnerability. We then normalized each layer and combined them using two different weighting schemes, including an ‘Even Weights’ and a ‘People’s Choice’ scenario based on a choice experiment embedded in a community survey. The survey indicated a preference for prioritizing the hydrology and sewer system criteria. Sweet spots for GSI implementation under each scenario were mapped based on the 90th percentile of the final combined key criteria layers. Comparisons between the two weighting schemes indicated a 73% overlap in sweet spot locations. We also found a small percentage (16%) of existing GSI in Lancaster overlapped with the sweet spots, indicating an opportunity to target future GSI implementation in the remaining sweet spots. Despite being demonstrated in a specific city, this relatively simple approach leveraging widely available spatial data can be applied and customized elsewhere and help improve future GSI siting methods.

A significant portion of the world's rural population does not have access to adequate sources of electricity and fuel to produce healthy food and clean water. Many rural areas, however, have an abundance of solar radiation which can be harnessed for cooking and water treatment. This paper presents the design and testing of a solar radiation and biosand filtration system that can provide cooking and water treatment capabilities. The proposed system addresses a need for a solar cooker that is durable, theft resistant, and efficient for use by an entire village. Thermal pasteurization is used for water treatment in the proposed system, and a built prototype is analyzed for heat transfer and water treatment efficiency. Water treatment is assessed through turbidity testing and Escherichia coli + other coliform counts. Given proper sunlight exposure, the proposed system reaches adequate temperatures to pasteurize water as documented with thermocouples, but testing in central Pennsylvania is difficult because of relatively low direct normal irradiance. A decrease in Escherichia coli and other coliform counts has been observed for post-treatment versus pretreatment water samples, but the counts are not sufficient to meet the Environmental Protection Agency drinking water standards. This correlates with the inability to maintain the warmer temperatures in central Pennsylvania during the cooler nights.

This paper focuses on specific information needed to model various aspects of the pollutant retention processes in stormwater biofilters. Updates currently being incorporated in WinSLAMM (Source Loading and Management Model) are building on expanded data from laboratory and field research mostly conducted by Pitt’s research group at the University of Alabama, Tuscaloosa, by Dr. Shirley Clark’s research group at Penn State–Harrisburg, and the Wisconsin Department of Natural Resources and the U.S. Geological Survey (DNR/USGS). These processes and data can be used in manual calculations or other models. Extensive summaries of these data sources and associated statistical analyses, plus additional references, are included in an online white paper available at the PV & Assoc. website. These tests were conducted to provide the details needed for modeling the performance of biofilters, specifically focusing on: methods to predict treatment flow rates through the media; particulate and associated particulate bound pollutant retention for several particle sizes; maintenance requirements due to sediment clogging and pollutant breakthrough; and retention of filterable pollutants. This multiyear research program also examined issues not commonly described in the biofilter performance literature, such as failure due to excessive salt loadings on media having large amounts of fines, problems associated with compaction of the media, and leaching of previously captured material from the media.

The complex chemistry of copper (Cu) in freshwater sediments at low concentrations is not well understood. We evaluated the transformation processes of Cu added to freshwater sediments under suboxic and anoxic conditions. Freshwater sediments from three sources in Michigan with different characteristics (Spring Creek, River Raisin, and Maple Lake) were spiked with 30 or 60 mg kg-1 Cu and incubated under a nitrogen atmosphere. After 28-d, each treatment subset was amended with organic matter (OM) to promote anoxic conditions and evaluate its effects on Cu speciation. OM addition triggered a shift from suboxic to anoxic conditions, and sequential extractions showed that Cu accordingly shifted from acid-soluble to oxidizable fractions. Extended X-ray absorption fine-structure (EXAFS) spectroscopy revealed that Cu sulfides dominated all anoxic samples except for Spring Creek 30 mg kgxfffd; 1, where Cu(I) was predominantly complexed to thiol groups of OM. Covellite and chalcopyrite (CuFeS2) were the predominant Cu species in nearly all anoxic samples, as determined by Raman spectroscopy, scanning electron microscopy, and X-ray absorption near-edge structure (XANES) spectroscopy. Copper reduction also occurred under suboxic conditions: for two of three sediments, around 80% had been reduced to Cu(I), while the remaining 20% persisted as Cu(II) complexed to OM. However, in the third coarsest (i.e., Spring Creek), around 50% of the Cu had been reduced, forming Cu(I)-OM complexes, while the remainder was Cu(II)-OM complexes. Toxicity tests showed that survival of H. azteca and D. magna were significantly lower in suboxic treatments. Anoxic sediments triggered a near-complete transformation of Cu to sulfide minerals, reducing its toxicity.

This research demonstrates the feasibility and efficacy of removing heavy metals from aqueous solutions using waste banana and orange peels. The fruit peels are carbonised, without the addition of chemical substances, to enhance their adsorption capacities. The adsorption capacities are studied in aquatic solutions containing individual and combined metal ions of hexavalent chromium (Cr 6+ ), copper (Cu) and zinc (Zn). The selectivity of the adsorbents towards these metal ions is also exhibited. The results show that both fruit peels exhibit a better selectivity towards zinc ions, followed by copper and then hexavalent chromium. The effects of operational conditions, including pH, adsorbent dosage, contact time and concentration of metal ions, on the removal efficiency and uptake capacity of the carbonised fruit peels are investigated. The optimal adsorption for both adsorbents occurs within 30 min of exposure and at an adsorbent dose of 0.5 g. Additionally, the adsorption kinetics and isotherms, including pseudo-second-order, Langmuir and Freundlich, are modelled for the obtained data.

Stormwater biofilters and bioretention controls have been extensively studied and are commonly encouraged as effective stormwater controls. Most of these controls incorporate media to enhance pollutant removal. There is much published research describing laboratory tests on the performance and selection of different media, and many field tests on media treatment of stormwater, but complementary long-term, full-scale field tests compared to prior laboratory tests are not as common. The purpose of this paper is to compare the laboratory evaluations of treatment media targeting a broad range of constituents of concern, to the results of long-term monitoring of full-scale stormwater controls using the selected media. The laboratory evaluations identified which media blend would reduce concentrations of constituents of concern to help meet National Pollutant Discharge Elimination System (NPDES) permit discharge limits and benchmarks, given site specific influent concentrations, when deployed in the field. Besides pollutant reductions, treatment flow rates and maintenance requirements were also of a consideration when selecting the media blend, especially determining the useful life of the media before clogging and/or pollutant breakthrough. Statistical comparison tests of the laboratory results with the full-scale field results resulted in similar effluent quality for most measured constituents (especially for lead and the critical form of dioxin), at all field treatment locations. Therefore, the laboratory observations were confirmed by the long-term, full-scale, stormwater control monitoring activities. The selected media has resulted in reductions in concentrations of the constituents of concern, over long periods of use. (C) 2021 American Society of Civil Engineers.

The adsorption of copper and zinc ions onto the modified diatomite with sodium hydroxide and manganese oxide (Mn-DM) was studied in isotherm batch solutions. The analysis of Cu (II) and Zn (II) results showed the effect of contact time and adsorbent dosage on the adsorption process performed in solutions with individual and combined metal ions, allowing observations of the selectivity and preference of modified diatomite in capturing Cu (II) and Zn (II). The paper also analysed the effect of supplementing peat on the adsorption process, at various ratios to the modified diatomite, to obtain the optimised filter composition with highest adsorption efficiency. The obtained data was used to model the kinetics of the adsorption processes for both metal ions.

Flat panel display glass (FPDG) from plasma televisions is difficult to recycle due to their heavy metal composition. When crushed, flat panel display glass has similar physical properties to sand and could be used as a recycled aggregate in concrete, if the potentially harmful metals in FPDG can be encapsulated. To replicate leaching from environmental exposure, at periodic points during freeze-thaw tests, samples of concrete with 0%, 10%, and 20% FPDG were exposed to simulated rainwater and the runoff water was analyzed. For the metals detected (arsenic, barium, chromium, and lead), lead concentrations in the leachate/runoff from 20% FPDG samples exceeded the acute ambient water quality criteria after approximately 50-60 cycles; however, no samples exceeded the toxic characteristic leaching procedure limits at any point during freeze-thaw testing. Increases in lead and chromium concentrations over time indicate a need for stabilization, especially since lead exceeded the acute water quality criteria. PRACTITIONER POINTS: TCLP results indicate flat panel display glass is not expected to release RCRA-8 metals at or above regulatory limits. Accelerated aging-leaching tests indicate lead might be released at levels approaching or exceeding the acute ambient water quality criteria. With additional lead stabilization, this study shows flat panel display glass has the potential to be used in concrete.

The water quality and quantity benefits of green roofs have been well documented. However, the transfer of the sun's heat through the roof to the building envelope has not been as well studied. This project addresses the knowledge deficit by testing thermal flux between the surface and the bottom of the green roof media operated under simulated winter and summer conditions and under saturated and dry conditions. Initial studies evaluated replacing expanded shale with crumb rubber. The results showed that when the surface was approximately 65 C, the temperature against the building envelope were 29 C for crumb rubber and 39 C for conventional media. Under saturated conditions, the initial measurements showed that crumb rubber still transfers less heat to the roof compare to the conventional material. Rubber also retained water longer, which kept the heat away from the roof due to slow evaporation of water. This translates to a considerable amount of energy saving in urban areas by using recycled tires as green roof materials. Further research will investigate other components of green roof media and the impact of vegetation on heat transfer, with the goal of improving existing models of building roof performance when a green roof is added.