Ikiensinma Gogo-Abite - BMP Trains Presentation - January 31, 2020

Dr. Ikiensinma Gogo-Abite\u27s slides from his PowerPoint presentation during the BMPTRAINS workshop on January 30-31, 2020

Slope Stability Of Laterite Soil Embankments

Embankments are key elements in the infrastructural development of structures such as dams, bridges, and roads. Residual soils are generally used as fills in the construction of embankments in areas were residual soils such as laterite is the dominant soil types. Laterite soils have the characteristics of losing its shear strength with time and in fully saturated conditions and its properties varies from region to region. The soil property is influenced by the chemical composition and the environment. The binding agent iron oxide in such soils changes its composition with time and in the presence of moisture. Sudden failures of embankments founded of laterite soils which were, otherwise, checked and found to be safe with high factor of safety, have been observed. This study is performed to investigate the stability of embankments with sudden loss of strength with time and when it is fully saturated. The research includes an investigation of the properties of laterite soils around the world, with particular emphasis on Nigeria. Initially, information is gathered from different sources about the strength-based properties of such soils. Previous research in Nigeria is used as a basis for obtaining real-world soil data. Next, stability analyses are performed using SLOPE/W with shear strength parameters for total stress (short-term), effective stress (long-term), and fully saturated soil conditions. A probability analysis is conducted for the fully saturated conditions because of the variability in the input parameters. Three slope configurations (1:1, 2:1, and 3:1) are considered. The study revealed that the laterite soils embankments lose most of its stability over time period and in full saturation soil conditions. Both these conditions significantly compromise the strength of the soil and the related stability of slopes. To consolidate all information, a database of the properties of laterite soils in some localities of Nigeria was created on the geographic information system (GIS), in order provide a quick access to information on laterite soils in Nigeria

Effluent Water Quality Improvement Using Silt Fences And Stormwater Harvesting

Construction sites are among the most common areas to experience soil erosion and sediment transport due to the mandatory foundation tasks such as excavation and land grubbing. Thus, temporary sediment barriers are installed along the perimeter to prevent sediment transport from the site. Erosion and sediment transport control measures may include, but not limited to, physical and chemical processes such as the use of a silt fence and polyacrylamide product. Runoff from construction sites and other impervious surfaces are routinely discharged into ponds for treatment before being released into a receiving water body. Stormwater harvesting from a pond for irrigation of adjacent lands is promoted as one approach to reducing pond discharge while supplementing valuable potable water used for irrigation. The reduction of pond discharge reduces the mass of pollutants in the discharge. In the dissertation, presented is the investigation of the effectiveness of temporary sediment barriers and then, development of a modeling approach to a stormwater harvesting pond to provide a comprehensive stormwater management pollution reduction assessment tool. The first part of the research presents the investigation of the performance efficiencies of silt fence fabrics in turbidity and sediment concentration removal, and the determination of flowthrough-rate on simulated construction sites in real time. Two silt fence fabrics, (1) woven and the other (2) nonwoven were subjected to material index property tests and a series of field-scale tests with different rainfall intensities and events for different embankment slopes on a tilting test-bed. Collected influent and effluent samples were analyzed for sediment concentration and turbidity, and the flow-through-rate for each fabric was evaluated. Test results revealed that the woven and nonwoven silt fence achieved 11 and 56 percent average turbidity reduction iv efficiency, respectively. Each fabric also achieved 20 and 56 percent average sediment concentration removal efficiency, respectively. Fabric flow-through-rates were functions of the rainfall intensity and embankment slope. The nonwoven fabric exhibited higher flow-throughrates than the woven fabric in both field-scale and laboratory tests. In the second part of the study, a Stormwater Harvesting and Assessment for Reduction of Pollution (SHARP) model was developed to predict operation of wet pond used for stormwater harvesting. The model integrates the interaction of surface water and groundwater in a catchment area. The SHARP model was calibrated and validated with actual pond water elevation data from a stormwater pond at Miramar Lakes, Miramar, Florida. Model evaluation showed adequate prediction of pond water elevation with root mean square error between 0.07 and 0.12 m; mean absolute error was between 0.018 and 0.07 m; and relative index of agreement was between 0.74 and 0.98 for both calibration and validation periods. The SHARP model is capable of assessing harvesting safe-yield and discharge from a pond, including the prediction of the percentage of runoff into a harvesting pond that is not discharged. The combination of silt fence and/or polyacrylamide PAM before stormwater harvesting pond in a treatment train for the reduction of pollutants from construction sites has the potential of significantly exceeding a performance standard of 85 percent reduction typically required by local authorities. In fact, the stringent requirement of equaling pre- and post-development pollutant loading is highly achievable by the treatment train approach. The significant contribution from the integration of the SHARP model to the treatment train is that real-time assessment of pollutant loading reduction by volume can be planned and controlled to achieve target performance standards

Stormwater Harvesting Using Retention and In-Line Pipes for Treatment Consistent with the new Statewide Stormwater Rule

Stormwater rules and regulations are evolving. Thus, there is a need for research that supports alternative methods for water quality treatment of runoff water. The information in this report supports the use of filtration media called Biosorption Activated Media (BAM) that improves runoff water quality. Runoff to impaired waters may need additional treatment or reduced volume of discharge to meet a mass discharge limitation. In addition, some nutrients in runoff waters may need to be removed before they percolate to nutrient sensitive areas such as aquifers with discharge to springs or estuaries. Thus, stormwater harvesting or reuse is another best management practice that can be used to reduce the mass of pollutants in runoff discharged to surface waters. Harvesting of stormwater for a single user is typically done by direct use of the water from a pond provided there is no cross connection and that a screen filter is used. When contact with the general public is expected, irrigation quality water is needed. The water in a stormwater pond has to be treated by some form of filtration to provide irrigation quality water. Treatment methods considered within this report are those resulting from biosorption filtration media, commonly called BAM, and from disc technologies. When using BAM, the media can be placed in a pipe or other suitable containment and the runoff water or wet detention pond water passes through the filter in either a down-flow or up-flow configuration. Another option is to place BAM in a pipe within a pipe in a wet detention pond and draft the water through the pipe. This BAM pipe-in-pipe can then be moved from one location to another, and thus is considered to be a mobile treatment method. Some options for the use of BAM are called pipe treatment systems because of their practical installation configurations. Harvesting can also occur after runoff water has infiltrated into the ground, such as from shoulder or swale areas adjacent to roadways. This infiltrated water can either be collected by compartments (pipes are common) or be allowed to further percolate into the ground until they reach a point of discharge. A concern resulting from harvesting water from a wet detention pond is the potential effect on the surrounding wetlands when the water in a wet detention pond is lowered. Thus, a computer model was developed and tested to determine the safe yield of a wet detention pond as controlled by the harvesting schedule and the minimum ground water level at select points in the study area. This integrated surface and ground water model was used for Stormwater Harvesting and Assessment for Reduction of Pollution and is thus called the SHARP model. The model was tested at an interstate highway wet detention pond in Miramar, Florida. BAM filtration media mixes were laboratory tested for pollution removal and filtration rates. The laboratory work was conducted in six inch diameter columns, and the media mix depth was equal to what was expected in a full-scale operating filter (2 feet depth is common). The media mixes were then installed in pipes placed in operation at existing wet detention ponds, and effectiveness in the removal of nutrients was documented. A wet detention pond in Tampa receiving runoff from an urban watershed composed of highways, parking lots, and buildings was the site of the down-flow filter. The down-flow media filter for water from this wet detention pond was successful in removing pollution. Another wet detention pond in Sarasota County was used as a demonstration for an up-flow filter. This pond collects both highway and residential runoff. The up-flow filter operation was demonstrated to include a backwashing operation and at a filtration rate of up to 2 million gallons per day. Both ponds require installation of provisions for removing debris and with mechanisms to backwash the filter media. A reliable and redundant operation was demonstrated since the water quality in the wet detention ponds did not meet a majority of the irrigation water quality standards. A mobile pipe-in-pipe system was also demonstrated, but application at a high rate of filtration provided marginal improvement in water quality. Due to this, a lower filtration rate was recommended. This system can also be used in emergency situations. The water quality effectiveness and continual operation of disc filtration using water from an interstate highway wet detention pond in Miramar, Florida was also documented. A disc filter was an alternative to filtration using BAM. It provided reliability and redundancy in meeting irrigation quality standards. A swale filter system using BAM was also demonstrated and water quality effectiveness documented. The BAM filter removed more pollutants relative to the use of parent soils documented as Type A-3 soils. The removal was especially significant when new sod was used on top of the BAM filter. Runoff not collected in the slope of the swale can be collected in the bottom of the swale if not transported. This collection can be enhanced with the use of exfiltration or French drains. Also, since filtration is assumed using at least two feet of media, the collected water can be reused. Example calculations for a BAM filter with a swale were presented. Every time runoff water is not discharged, pollution removal can be expected. This pollution removal can be quantified and the total maximum daily load reduction estimated. Limited cost and removal information for these systems are presented

Performance Evaluation Of Two Silt Fence Geotextiles Using A Tilting Test-Bed With Simulated Rainfall

This paper presents the results of the investigation of the performance efficiencies of silt fence fabrics in turbidity and sediment concentration removal, and the determination of flow-through-rate on simulated construction sites in real time. Two silt fence fabrics, (1) a woven type and (2) a nonwoven type, were subjected to material index property tests and a series of field-scale tests. The fabrics were tested for removal efficiency by varying the rainfall intensities and events for different embankment slopes on a tilting test-bed. Collected influent and effluent samples were analyzed for sediment concentration and turbidity, and the flow-through-rate for each fabric was evaluated. Test results revealed that the woven and nonwoven silt fence achieved 14 and 52 percent average turbidity reduction efficiency, and 23 and 56 percent average sediment concentration removal efficiency, respectively. Evaluation of sediment concentration reduction based on percent removal does not correctly account for the sediment concentration transported and deposited downstream. Fabric flowrates were functions of the rainfall intensity, embankment slope and field conditions, and fluctuates with every rainfall event. © 2013 Elsevier Ltd

Performance evaluation of two silt fence geotextiles using a tilting test-bed with simulated rainfall

This paper presents the results of the investigation of the performance efficiencies of silt fence fabrics in turbidity and sediment concentration removal, and the determination of flow-through-rate on simulated construction sites in real time. Two silt fence fabrics, (1) a woven type and (2) a nonwoven type, were subjected to material index property tests and a series of field-scale tests. The fabrics were tested for removal efficiency by varying the rainfall intensities and events for different embankment slopes on a tilting test-bed. Collected influent and effluent samples were analyzed for sediment concentration and turbidity, and the flow-through-rate for each fabric was evaluated. Test results revealed that the woven and nonwoven silt fence achieved 14 and 52 percent average turbidity reduction efficiency, and 23 and 56 percent average sediment concentration removal efficiency, respectively. Evaluation of sediment concentration reduction based on percent removal does not correctly account for the sediment concentration transported and deposited downstream. Fabric flowrates were functions of the rainfall intensity, embankment slope and field conditions, and fluctuates with every rainfall event. © 2013 Elsevier Ltd

Evaluation Of Silt Fence Materials During And After Rainfall Events

Silt fence is a temporary sediment control device used on construction sites for the purpose of reducing the discharge of sediment-laden runoff. Previous studies on the performance of silt fence fabrics have evaluated the sediment removal and turbidity reduction efficiencies as the performance after a rainfall event to be the true representation of the overall efficiencies. However, recent studies at the University of Central Florida have revealed that the removal efficiencies were significantly impacted by the time of sampling, during and after the rainfall event. Runoff generated during a rainfall event caused turbulent flow conditions within the ponding water volume created by the silt fence. Due to these turbulent conditions, the settling potential of suspended solids and the removal efficiency of the silt fence were severely diminished. This paper examined the performance of woven and nonwoven silt fence fabrics in turbidity and sediment removal during and after a rainfall event. Test results show that, for a silty-sand embankment of 10H:1V and 3H:1V slope, the woven silt fence fabric achieved average turbidity reduction efficiencies of 39 and 74 percent during and after the rainfall event, respectively. The nonwoven silt fence fabric achieved turbidity reduction efficiencies of 59 and 91 percent during and after the rainfall event, respectively. Copyright © (2014) by the International Erosion Control Association

Integrated Surface-Groundwater Model For Storm-Water Harvesting Using Basic Mass Balance Principles

Storm-water harvesting from a pond for irrigation of adjacent lands is promoted as one way that may reduce pond discharge while supplementing valuable potable water used for irrigation. Reduction of pond discharge reduces the mass of pollutants in the discharge. In this study, a storm water harvesting and assessment for reduction of pollution (SHARP) model was developed to predict operation of a wet pond used for storm-water harvesting at Miramar Lakes, Miramar, FL. The model integrates the interaction of surface water and groundwater in a catchment area. The SHARP model was calibrated and validated for pond-water elevation. Model evaluation showed adequate prediction of pond-water elevation with root mean square error (RMSE) between 0.07 and 0.12 m, mean absolute error (MAE) between 0.018 and 0.07 m, and relative index of agreement (drel) between 0.74 and 0.98 for both calibration and validation periods. The SHARP model is capable of assessing harvest safe yield and discharge from a pond, including the prediction of the percentage of runoff into a harvesting pond that is not discharged. © 2013 American Society of Civil Engineers

Evaluation Of Mechanical Properties And Structural Integrity For Pervious Concrete Pavement Systems

Pervious concrete pavements (PCP) are increasingly recognized and used as a best management practice to control stormwater runoff and for low-volume traffic. However, there are limited studies on the structural integrity of the PCP section on performance under vehicular loads. This study investigated the mechanical properties of field samples and the structural integrity of PCP when subjected to traffic loads using the falling weight deflectometer (FWD). The compressive strength for cored samples from the field installation was about 11.5 MPa with an average unit weight of 1,792 kg/m3. The deflection of the PCP sections at the load application point was about 1.7 to 4 times of the impervious concrete section, dependent on the subbase characterization. The composition of the PCP subbase materials and the compaction effort of the layers significantly affected the deflection. Back-calculation analysis showed that the loosely compacted subbase layers had lower elastic moduli and exhibited higher deflection responses, which compromised the structural integrity of the PCP systems to traffic loadings. © 2014 American Society of Civil Engineers

In Situ Permeability Determination Device For Porous Pavement Systems

Porous pavement systems allow for the percolation of rainwater through the system to the underlying subsoil, which results in reduced runoff and pollutant transport. Several devices have been proposed and/or developed to determine the infiltration rates of the porous pavement systems. However, most of the devices only provide the infiltration rate of the pavement system surface layer, or are destructive techniques such as pavement coring for laboratory testing. The objective of this study was to develop and test the efficacy of a new testing device, called the embedded ring infiltrometer kit (ERIK), for field determination of the in situ permeability of porous pavement systems. The ERIK device provides a means to measure the pavement system\u27s surface course percolation rate as a maintenance indicator and the entire pavement system to evaluate a recovery time throughout the service life. Performance evaluation of the ERIK device showed good reproducibility with a coefficient of variation equal to 7% and repeatability at a 95% confidence interval. The results suggested that the ERIK device is a viable option for field determination of in situ permeability of porous pavements