Surface Runoff from Full-Scale Coal Combustion Product Pavements during Accelerated Loading

In this study, the release of metals and metalloids from full-scale portland cement concrete pavements containing coal combustion products (CCPs) was evaluated by laboratory leaching tests and accelerated loading of full-scale pavement sections under well-controlled conditions. An equivalent of 20 years of highway traffic loading was simulated at the OSU/OU Accelerated Pavement Load Facility (APLF). Three types of portland cement concrete driving surface layers were tested, including a control section [i.e., ordinary portland cement (PC) concrete] containing no fly ash and two sections in which fly ash was substituted for a fraction of the cement; i.e., 30% fly ash (FA30) and 50% fly ash (FA50). In general, the concentrations of minor and trace elements were higher in the toxicity characteristic leaching procedure (TCLP) leachates than in the leachates obtained from synthetic precipitation leaching procedure and ASTM leaching procedures. Importantly, none of the leachate concentrations exceeded the TCLP limits or primary drinking water standards. Surface runoff monitoring results showed the highest release rates of inorganic elements from the FA50 concrete pavement, whereas there were little differences in release rates between PC and FA30 concretes. The release of elements generally decreased with increasing pavement loading. Except for Cr, elements were released as particulates (>0.45?μm) rather than dissolved constituents. The incorporation of fly ash in the PC cement concrete pavements examined in this study resulted in little or no deleterious environmental impact from the leaching of inorganic elements over the lifetime of the pavement system.     

Biofilm Growth and Mineral Precipitation in Synthetic Leachate Columns

The results of a numerical model developed to describe the clogging of the leachate collection systems are compared with data from column experiments conducted with synthetic landfill leachate. A biofilm kinetic model is used to calculate the utilization of organic substrates (acetate and propionate) and growth of active clog material, and the substrate removal is then linked to mineral precipitation. Calculated changes in the chemical oxygen demand and Ca2+ of the effluent leachate and the porosity profiles along the length of the column show encouraging agreement with measured values. Means to obtain reasonable parameter values are presented. The favorable outcome represents completion of an essential first step toward being able to predict what controls clogging in landfill leachate collection systems.     

Long-Term Field Performance of Cold In-Place Recycled Roads in Iowa

Cold in-place recycling (CIR) is one of the most effective methods to rehabilitate asphalt pavements. In fact, most CIR roads have performed well at low cost in Iowa since the first CIR road was constructed in 1986. However, some CIR roads have reached failures earlier than their expected design lives because there is no design standard for designing CIR roads with a limited amount of past performance information. Some of the most prominent problems seemed to have come from selecting CIR in areas where there are poor subgrades. Therefore, it is critical to collect CIR performance data along with falling weight deflectometer (FWD) data in order to develop performance models. The main purpose of this paper is to document that effort. The performance models were developed on the basis of historical data collected from CIR roads in Iowa. First, an inventory of CIR roads was created which includes construction information, subgrade and base characteristics, and traffic levels. In consideration of pavement age, level of traffic, and subgrade condition, 26 test sections were selected from the inventory of CIR roads and pavement surface distress surveys were conducted on these roads using an automated image collection system. Distress data were then compiled to compute pavement condition index (PCI) for each test section. FWD data were collected from each test section to determine its relative soil support condition. Finally, to determine their long-term performance, the PCI values were plotted against the pavement age for each group of pavements categorized by their soil support conditions and traffic levels. Overall, it can be concluded that the CIR roads in Iowa, all under traffic level of annual average daily traffic of 2,000, have performed very well and predicted to last up to 25 years before reaching the poor condition (PCI = 40) when the pavements are to be rehabilitated. The CIR roads with a good subgrade support, however, are predicted to last up to 35 years.     

Effects of Organic Matter on Physical, Strength, and Volume Change Properties of Compost Amended Expansive Clay

In recent years, the recycling and composting of municipal solid wastes has gained acceptance as an alternative to landfilling and incineration. Compost materials have been used as soil amendments in landscaping, erosion control, expansive soil treatment, and turf management. Compost amended soils are enriched with decomposed organic matter and hence usually exhibit different strength and compressibility in soil behaviors. An experimental investigation was carried out on compost amended soils to understand the effects of decomposed organic matter on strength and volume change properties. Two types of composts, a biosolids compost and a dairy manure compost, and a control cohesive soil were chosen as test materials. Tests conducted on these materials showed that the presence of organic matter enhanced shrinkage resistance and shear strength at low compost proportions (20–30%). At high proportions (beyond 30%), the shear strength reached plateau conditions. One-dimensional vertical swell and secondary consolidation properties increased with an increase in compost proportions. As low proportions of composts yielded better enhancements to most expansive soil properties, it was concluded that compost materials can provide engineering benefits to control soils when used in moderate proportions.     

Evaluation of Four Permeable Pavement Sites in Eastern North Carolina for Runoff Reduction and Water Quality Impacts

Four permeable pavement applications in North Carolina’s Coastal Plain were constructed and monitored to determine their effectiveness of reducing runoff quantity and improving water quality. Sites were either constructed of permeable interlocking concrete pavers (2), porous concrete (1), or concrete grid pavers (1). One site of each pavement type was monitored for runoff reduction for periods ranging from 10 to 26 months. Measured runoff depths from rainfall events over 50?mm were used to determine permeable pavement equivalent curve numbers for the sites, which ranged from 45 to 85. Only the two permeable interlocking concrete pavement (PICP) sites were monitored for water quality. Runoff and exfiltrate samples were intended to be collected, in addition to runoff monitoring, from the Swansboro PICP site. However, no runoff was produced during this study from the Swansboro PICP site for rainfall events up to 88?mm. From exfiltrate concentrations, nutrient retention was estimated to be 3.4 and 0.4?kg/ha/year for total nitrogen and total phosphorus, respectively. For the Goldsboro PICP site, water quality of asphalt runoff and PICP exfiltrate were compared. Analysis of water quality samples from the second site determined that concentrations of total Kjeldahl nitrogen, ammonia, total phosphorus, and zinc were significantly (p ? 0.05) lower in permeable pavement exfiltrate than asphalt runoff.     

Effects of a Permeable Friction Course on Highway Runoff

This project documents the impact of a porous asphalt overlay on the quality and quantity of highway storm-water runoff. A permeable friction course, also known as open graded friction course, is a layer of porous asphalt approximately 50?mm thick, which is often applied on top of conventional asphalt or concrete highways to enhance safety and reduce noise. Storm-water runoff from a four-lane divided highway in the Austin, Texas area was monitored at two sites before and after the installation of a PFC. Observed concentrations of total suspended solids and pollutants associated with particulate material were much lower in the runoff from the PFC than that derived from the conventional asphalt surface. Concentration reductions were observed for total suspended solids, total lead, total copper, and total zinc at both monitoring locations. In addition to the above-mentioned constituents, concentrations of chemical oxygen demand and total Kjeldahl nitrogen were also lower in the runoff from the PFC at a site collecting paired samples from both pavement types. Concentrations of dissolved constituents were not significantly different and concentrations of polycyclic aromatic hydrocarbons were below the detection limit for both pavement types. The runoff coefficient for the PFC appears to be higher than for conventional pavements.     

Characterization of Rutting (Permanent Strain) Development of A-2-4 and A-4 Subgrade Soils under the HVS Loading

As part of a national pool funded study 208 on pavement subgrade performance, 12 full-scale test sections (four soil types and three moisture contents) were constructed and tested under the heavy vehicle simulator (HVS) loading. This paper presents the HVS results on two of the four soils tested: AASHTO Class A-2-4 and A-4 soils, respectively. From the results, it was found that the pavement subgrade performance is a function of soil type, moisture content, and applied stress condition. Additionally, this paper also evaluated the current mechanistic-empirical pavement design guide (MEPDG) subgrade rutting (permanent strain) model through comparing with the actual measurements under the HVS loading. It was found that the MEPDG subgrade permanent strain model needs further improvement, and that a single performance model may not be universally applicable to different subgrade soil types. Consequently, a new permanent strain model for each soil type was developed in this paper, based on the HVS results, and that yielded better predictions. With further validation and field calibration, the proposed models offer promising potential to accurately predict rutting behavior of these two soils.     

Pollutant Concentrations in Road Runoff: Southeast Queensland Case Study

This paper discusses the results of research into the pollutants in runoff from road pavement surfaces following natural rainfall events. Road runoff water quality was monitored at 21 sites centering around Brisbane, in southeast Queensland, Australia. The sites were selected according to traffic volumes, surrounding land use, pavement surface type, ease of access, and commercial vehicle percentage. Bridge sites were chosen for convenience of sample collection and minimized infrastructure modification. “First flush” grab samplers were permanently installed at each site to collect the first 20 L of runoff from one of the bridge drainage scuppers. The runoff samples were tested for a number of heavy metals, hydrocarbons, pesticides, and other physical characteristics. The observed results fall within the ranges of concentrations reported internationally and nationally but do not typically follow the “30,000 average annual daily traffic” results reported in the United States. Traffic volumes have not been found to be the best indicator of road runoff pollutant concentrations. Interevent duration has been found to be a statistically significant factor for pollutant concentrations. Sites incorporating exit lanes have recorded higher concentrations of acid-extractable copper and zinc, tending to support the hypothesis that brake pad and tire wear caused by rapid deceleration contributes to the concentrations of these metals in road runoff. Laser particle sizing has shown that a significant proportion of the sediment found in the runoff is <100 μm. However, these particulates do settle in water within 24 h, under laboratory conditions. This may be due to the presence of heavy metals.     

Field Evaluation of a Leachate Collection System Constructed with Scrap Tires

Landfilling costs and the potential uses of scrap tires have prompted researchers to investigate beneficial reuses. One important application is the use of tire chips as a leachate collection material in municipal solid waste landfills. Laboratory and field studies were conducted to investigate the performance of tire chips as a drainage medium in landfills. The laboratory portion of the program included a series of hydraulic conductivity and compressibility tests. Two field test cells, one with tire chips and another with gravel as the control, were constructed. The tire-chip cell was instrumented with flowmeters, thermistors, and gas collection devices to evaluate the hydraulic performance as well as the potential for spontaneous combustion. Leachate collected from the two cells was analyzed to determine if tire chips would potentially contaminate the groundwater. The results indicated that adequate drainage conditions were present within the tire-chip layer. The presence of insignificant quantities of carbon monoxide, and the lack of oxygen, and recorded low temperatures suggested that a combustion hazard was not present. The field leachate data indicated that tire chips can be safely used as part of a landfill leachate collection layer, even though it may not be suitable to place them near drinking water sources.     

Hydraulic Model for Sedimentation in Storm-Water Detention Basins

Treatment of storm-water runoff may be necessary before discharge to surface waters. In urban areas, space constraints limit selection of conventional treatment systems, and alternative systems are needed. This research program involves design and laboratory testing of a small footprint nonproprietary detention basin which consists of pipes and box culvert sections with a specialized inlet and outlet system. This system can be placed below grade near the roadway section as part of the conventional drainage system and does not require additional right-of-way. A mathematical model, based entirely on hydraulic principles, is developed to estimate particle removal efficiency of the rectangular detention basin for the treatment of storm-water runoff by extending ideal horizontal tank theory under the condition in which water level is varied. A physical model was built in 1/5 scale to measure particle removal performance and validates the conceptual model. Experiments were performed for steady inflow conditions with different inflow rates, durations, and suspended sediment concentrations. Measured time series outflow suspended sediment concentrations and particle removal efficiency compare well with calculated results from the conceptual model. The outflow particle-size distribution can also be estimated using the conceptual model.     

Neural plasticity, neuropeptides and anxiety in animals--implications for understanding and treating affective disorder following traumatic stress in humans

Phenolic composition, toxicity and biodegradability of three different phenolic leachates/samples was studied. Samples A and C were the leachates from the oil-shale industry spent shale dumps at Kohtla-J?rve, Estonia. Sample B was a laboratory-prepared synthetic mixture of 7 phenolic compounds mimmicking the phenolic composition of the leachate A. Toxicity of these 3 samples was analyzed using two photobacterial test (BioTox and Microtox), Daphnia test (DAPHTOXKIT F pulex) and rotifiers' test (ROTOXKIT F). All the LC50 values were in the range of 1-10%, leachate A being the most toxic. The growth and detoxifying potential (toxicity of the growth medium was measured using photobacterial tests) of 3 different phenol-utilizing bacteria and acclimated activated sludges was studied in shake-flask cultures. 30% leachate A (altogether 0.6 mM total phenolic compounds) was too toxic to rhodococci and they did not grow. Cell number of Kurthia sp. and Pseudomonas sp. in 30% leachate A increased by 2 orders of magnitude but despite of the growth of bacteria the toxicity of the leachate did not decrease even by 7 weeks of cultivation. However, if the activated sludge was used instead of pure bacterial cultures the toxicity of the 30% leachate A was eliminated already after 3 days of incubation. 30% samples B and C were detoxified by activated sludge even more rapidly, within 2 days. As the biodegradable part of samples A and B should be identical, the detoxification of leachate A compared to that of sample B was most probably inhibited by inorganic (e.g. sulphuric) compounds present in the leachate A. Also, the presence of toxic recalcitrant organic compounds in the leachate A (missed by chemical analysis) that were not readily biodegradable even by activated sludge consortium should not be excluded.     

Liquid Sodium Ferrate and Fenton’s Reagent for Treatment of Mature Landfill Leachate

As landfills mature, biodegradable matter in leachate is consumed and remaining compounds are increasingly recalcitrant. In this work, ferrate was compared to Fenton’s reagent for the purpose of removing nonbiodegradable organic compounds from mature leachate. Oxidation conditions (time, pH, and dose) were optimized to yield maximum organic removal using two leachate samples from 20- and 12-year-old solid waste cells. Results from this study demonstrated that Ferrate and Fenton’s reagent had similar optimum pH ranges (3–5), but different organic removal capacities, ranging from 54 to 79% of initial leachate organic contents. An advantage of ferrate was that it was effective over a wide pH range. Advantages associated with Fenton’s reagent include that it had higher organic removal capacity, produced more oxidized organic compounds (measured as chemical oxygen demand/dissolved organic carbon), and produced more biodegradable byproducts (measured as chemical oxygen demand/5-day biochemical oxygen demand). Finally, both treatments were found to attack larger molecules (>1,000?Dalton), as indicated by an increase in smaller molecule contribution to organic carbon.     

Predicting the Erosion Rate of Chemically Treated Soil Using a Process Simulation Apparatus for Internal Crack Erosion

Chemical stabilization is an effective ground improvement technique for controlling erosion. Two stabilizers, lignosulfonate and cement, were used to study how effectively they could stabilize erodible silty sand collected from Wombeyan Caves, NSW, Australia. To conduct this research, four dosages of cement (0.5, 1, 1.5, and 2%) and four dosages of lignosulfonate (0.1, 0.2, 0.4, and 0.6%) by dry weight of soil were selected. All treated and untreated soil specimens were compacted to 90 and 95% of their maximum dry density to study the effect of compaction level on erodibility. The erosion characteristics of treated and untreated soil samples were investigated using a process simulation apparatus for internal crack erosion designed and built at the University of Wollongong. The findings of this study indicated that both chemical stabilizers increased the resistance to erosion because of their cementing properties. It was also found that the critical shear stress increased linearly with the amount of stabilizer, and the coefficient of soil erosion decreased as a power function of the critical shear stress.     

NJTxtr—A Computer Program Based on LASER to Monitor Asphalt Segregation

Abstract: This paper describes the research funded by the New Jersey Department of Transportation to develop an automated technology to monitor segregation during construction of hot-mix asphalt concrete pavements. A Laser-based system was used to measure surface texture and to detect segregation. Two segregated test sections and a control test section were tested to evaluate the applicability of Laser texture method to detect and quantify segregation. Laser texture data were gathered from all three sections. Ratios of texture in segregated areas to that in nonsegregated areas were set as the basis for detection of different levels of segregation. By combining the level of segregation and extent of segregation, an AREA index was developed to determine the acceptability of a pavement section. Based on AREA index, pay adjustment factors were proposed to reduce the payment to account for loss of pavement life due to segregation. Further remedial actions were proposed to correct segregated pavement sections with acceptable AREA index. Based on the above concepts, Windows-based computer program NJTxtr was developed to detect and quantify segregation. This computer program uses the Laser-equipment-collected pavement texture data and determines whether the pavement section is acceptable or unacceptable based on the level of segregation within a pavement section, and provides bonus or penalties to the contractor. The paper describes a novel technology using laser and associated software for construction quality control of asphalt concrete pavements. The proposed methodology was applied to detect segregation in an interstate highway section in New Jersey, and this section was repaved based on visual observation and recommendation from this study.     

Clogging of Gravel Drainage Layers Permeated with Landfill Leachate

Ten flow cells, called mesocosms, are used to investigate the effect of different gravel sizes (38 and 19?mm) and operating conditions on clogging of leachate collection systems. These mesocosms simulated in real time and real scale the two-dimensional leachate flow conditions representative of a section of a continuous 300-mm-thick gravel drainage blanket adjacent to a leachate collection pipe in a primary leachate collection system. The tests were terminated after 6–12?years of operation. In some mesocosms the full 300?mm of gravel was saturated. In others, the leachate level was initially set at 100?mm and the upper 200?mm were unsaturated. Although the flow through all mesocosms was similar, the clogging in the fully saturated gravel was substantially more than in the partially saturated gravel. After 6?years of operation, typically, less than 10% of the initial pore space was filled with clog material in the unsaturated gravel. For the saturated zone, 45% of the initial pore space was filled with clog material in the fully saturated design as compared to only 31% in the partially saturated design. The 38?mm gravel performed much better than the 19?mm gravel. For example, it maintained a hydraulic conductivity that was higher than the 19?mm gravel even after operating for twice as long. Up to four mesocosms were placed in series, with the effluent from one mesocosm being the influent for another. The reduction in mass loading within the first mesocosm reduced the amount of clogging within the mesocosm later in series. There was a clear progression of decreasing amounts of initial pore space filled with clog material in the last mesocosm in series, and most of the clogging was due to the vertically percolating leachate.     

In Situ Partial Exfiltration of Rainfall Runoff. II: Particle Separation

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

Probabilistic Models for Analysis of Urban Runoff Control Systems

Given the significant urban runoff impacts on many receiving waters and the massive costs of future investments in drainage infrastructure, the design of urban runoff control systems must be cost-effective. Cost-effective design requires that various runoff control system alternatives be investigated at the planning stage so that cost-effective runoff control systems can be identified for design level analysis. To analyze the runoff control performance of various combinations of runoff control systems at the planning stage, efficient screening models are acutely needed. For this purpose, analytical probabilistic models were applied to analyze the runoff quantity∕quality control performance of various combinations of storage and treatment systems. These analytical probabilistic models are developed with derived probability distribution theory whereby the input meteorology to the catchment is described by probability density functions (PDFs) of the meteorological characteristics that are transformed by hydrologic/hydraulic functions to PDFs of the system performance variables. The resulting PDFs are then used to determine the average performance conditions. These models provide closed-formed solutions of the performance equations that are highly efficient in both a conceptual and computational sense. As a result, they are particularly useful for the screening analysis of urban runoff control alternatives.     

Field Data from a Capillary Barrier and Model Predictions with UNSAT-H

Water balance data are presented from a capillary barrier test section located on the final cover of a municipal solid waste landfill in a semiarid region (E. Wenatchee, Washington, U.S.). Water balance and meteorological data were collected from November 1992 to August 1995. Estimates of the water balance were made using the program UNSAT-H, with input consisting of meteorological data, soil properties, and vegetative information. Estimates of evapotranspiration and soil-water storage by UNSAT-H agree reasonably well with the field data. Peak soil-water storage was underestimated during the winter and evapotranspiration was overestimated in late winter. Water contents were estimated reasonably, although the changes in water content of the sand obtained from UNSAT-H were not as large as, and occurred less quickly than, that in the field. Percolation was generally overestimated, with the greatest overestimation occurring during Winter 1993, which had substantial snowfall. Surface runoff was underestimated; no runoff was obtained from UNSAT-H, whereas 7.4 cm of runoff was measured in the field. The overestimates in percolation appear to be closely related to underestimates in runoff and extra storage in the sand layer caused by the geocomposite drain used in the test section. Snowmelt, freezing of the soil surface, and hysteresis in soil hydraulic properties also appear to have had an effect on the differences between estimated and measured water balances.     

Innovative Data Acquisition for Heavily Instrumented Flexible Pavements

A data acquisition program was written to allow independent triggering of multiple test sections of a thin flexible pavement. A total of 129 electronic sensors were installed in 17 test sections and subjected to 2,100 truck passes over several months immediately after construction. The measured strains were highly variable in the thin flexible pavement, but the program was still able to successfully trigger each section independently. The majority of signal processing was also performed within the program, which was written in Lab VIEW 7 Express. This approach significantly reduced the amount of postprocessing effort that would have otherwise been required. The quality of the triggering approach was compared to independently collected weigh in motion data. The majority of the test sections recorded within 0.5% of the number of vehicles recorded by the weigh in motion system. Key components of all major facets of the data acquisition and programming performed are discussed in detail.     

LIGAND database for enzymes, compounds and reactions

LIGAND is a composite database consisting of three sections and containing the information of chemical substances, chemical reactions and enzymes that catalyze reactions. The COMPOUND section is a collection of metabolic compounds, as well as macromolecules, chemical elements and other chemical substances in a living cell. The ENZYME section is a collection of all known enzymatic reactions, together with the information of enzyme molecules, classified according to the EC (Enzyme Commission) numbers. The REACTION section is a new addition to the database containing metabolic reactions that appear in the pathway diagrams of the KEGG/PATHWAY database and/or in the ENZYME section. The LIGAND database can be accessed through the WWW (http://www.genome.ad.jp/dbget/ligand.html) or may be downloaded by anonymous FTP (ftp://kegg.genome.ad. jp/molecules/ligand).