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To identify the required parameters of grouting operations in scrutinising the design and execution of seal curtain of the Balvabin dam site, the test grouting operations were conducted in a part of the seal curtain zone located in the riverbed. The test grouting was carried out in the vertical and angled rows according to the properties of discontinuities in the dam foundation zone to intersect the maximum discontinuities. Afterwards, the obtained results were analysed and finally due to the not groutable of the rock mass at the depths of more than 10 metres and according to the presence of peripheral gallery in the foundation, the execution of seal grouting operations was postponed until next dewatering. The measurements after the dewatering of the dam indicate whether grouting is required or it can be eliminated. With the grouting gallery being available, the grouting can be carried out at any other time. [ABSTRACT FROM AUTHOR]

Groundwater seepage into open pit mines must be controlled carefully. Slope instability, dewatering of blast holes, and mining operations below the groundwater table are important issues caused by groundwater seepage into the Gol-Gohar open pit mine, Iran. There are several methods to overcome these problems, such as construction of cut-off walls, ditches and sumps, horizontal drains, and pumping wells. Drilling of a new pumping well has several difficulties in which the determination of its location is a major issue. In this study, a stochastic simulation approach called simulated annealing was used to determine the best possible locations for new pumping wells. Three major groundwater variables, including the groundwater level, electrical conductivity, and transmissivity were selected for the geostatistical study. The results of simulations showed reliable correlation (Pearson) between the variables. Comparison of the variograms at different depths of the Gol-Gohar pit mine revealed that the effect of faults intensified with increasing depth. The best potential locations for drilling of new pumping wells were identified by the use of multi-criteria decision analysis performed on the simulation results. This method can be used in other regions with similar hydrogeological settings. [ABSTRACT FROM AUTHOR]

Electro-osmosis is a phenomenon describing the motion of liquid adjacent to a charged surface under the influence of an electric field. Electro-osmosis is considered as an efficient soft soil improvement technique. In this study, series of laboratory tests were performed utilizing graphite and stainless steel electrodes under three levels of voltage gradients for 28 days using the soil from north of Iran to investigate the effect of various parameters on electro-osmotic and geotechnical properties. Moreover, the microstructure and chemical analyses of the soil before and after treatment gave an in-depth perspective to underlying mechanism of this process. Water drainage which has the most important effect on consolidation of soils, terminated after a few days. The termination time for stainless steel is smaller than graphite and the whole drained water volume is larger in case of stainless steel compared to graphite. The strength around the anode is larger than that of the cathode zone and the stainless steel electrode induced larger strength than the graphite electrode. The SEM images exhibited the agglomeration of the soil after electro-osmosis treatment, and some precipitation was also identified, which was attributed to iron based compounds. Chemical analysis illustrated that the concentration of calcium ions decreased around the anode and increased near the cathode while Fe and Al amount did not change significantly, implying the ion exchange and ion migration due to the electro-osmosis process. Additionally, the stainless steel electrode introduced iron and chrome ions to the soil, which affected structure and chemical distribution of the ions. • Electro-osmosis changed the microstructure of the soil and decreased the void volume of the soil. • The Calcium and Magnesium ions were substituted by iron and Aluminum ions and migrated through the soil. • The geotechnical properties of plastic soil improved. • The stainless steel electrode had better performance compared to graphite electrode. [ABSTRACT FROM AUTHOR]

In this research, application of chemical conditioners for the conditioning of sludge and their effects on the improvement of sludge thickening of the wastewater treatment plant in the city of Bojnourd (Iran) is investigated. The concentration of chemical conditioners, pH and coagulation and flocculation time is from among the parameters studied in this research work. The results obtained indicate that sludge volume reduction for the chemical conditioners used, including Ferric Chloride (FeCl 3 ), Aluminum Sulfate (Al 2 (SO 4 ) 3 ), and Calcium Oxide (CaO) are 41, 17, and 33 percent, respectively. The optimal concentration for FeCl 3 , Al 2 (SO 4 ) 3, and CaO are 550, 1100, and 292 mg/L, respectively, and the optimal values of pH are 9, 7.5, and 10, respectively. The time to filtration (TTF) and reduction in sludge moisture content (SMC) for Ferric Chloride, Aluminum Sulfate, and Calcium Oxide are 45 s and 6.2%, 135 s and 3.3%, 190 s and 2.4% respectively. PRACTITIONER POINTS: Investigating the sludge conditioning by Ferric Chloride, Aluminum Sulfate, and Calcium Oxide. Determining the optimal concentration, pH, and coagulation/flocculation time. Calculating the time to filtration (TTF) and reduction in sludge moisture content (SMC). Predicting the settled sludge volume using descriptive statistical analysis., (© 2021 Water Environment Federation.)