Hydraulic Conductivity Testing and Destructive Sampling of Field-Scale Mine Waste Test Piles

2021 ◽  
Author(s):  
Mohammad R. H. Gorakhki ◽  
Christopher Bareither ◽  
Joseph Scalia
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Mine Waste ◽  
Average Density ◽  
Waste Rock ◽  
Dry Density ◽  
Wetting Front ◽  
Destructive Sampling ◽  
Double Ring ◽  
Test Pile

A commingled waste rock and tailings test pile and a waste rock test pile were evaluated to determine saturated hydraulic conductivity and destructively sampled to measure dry density. The commingled test pile contained a mixture of filtered tailings and waste rock blended to isolate waste rock particles as inclusions within the tailings matrix. Test piles were constructed in the shape of truncated 5-m tall pyramids with 25-m base sides and flat 5-m × 5-m top surfaces, and instrumented to monitor water content (and additional geochemical indicator parameters) within the test pile and seepage from the base of the pile. Piles were decommissioned after 26 months of operation. Saturated hydraulic conductivities were measured using sealed double ring infiltrometers (2.4-m square outer-ring and 1-m square inner-ring). Tensiometers and embedded water content sensors were used to measure progression of the wetting front, and the final location of the wetting front in the commingled test pile was directly measured during decommissioning. Field-measured saturated hydraulic conductivities were compared to laboratory-measured results intended to simulate the test piles. Despite having a lower average density, the commingled waste rock and tailings had a hydraulic conductivity approximately 2.5-times lower than the waste rock.

Hydraulic Conductivity of Compacted Tropical Clay Treated with Rice Husk Ash

2011 ◽  
Vol 367 ◽  
pp. 63-71 ◽  
Author(s):  
Adrian O. Eberemu ◽  
Agapitus A. Amadi ◽  
Joseph E. Edeh
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Rice Husk ◽  
Industrial Waste ◽  
Rice Husk Ash ◽  
Waste Product ◽  
Dry Density ◽  
Waste Containment ◽  
Hydraulic Behaviour ◽  
Waste Containment Systems

Laboratory study on compacted tropical clay treated with up to 16% rice husk ash (RHA), an agro-industrial waste; to evaluate its hydraulic properties and hence its suitability in waste containment systems was carried out. Soil-RHA mixtures were compacted using standard Proctor, West African Standard and modified Proctor efforts at-2, 0, 2 and 4% of optimum moisture content (OMC). Compacted samples were permeated and the hydraulic behaviour of the material was examined considering the effects of moulding water content, water content relative to optimum, dry density and RHA contents. Results showed decreasing hydraulic conductivity with increasing moulding water content and compactive efforts; it also varied greatly between the dry and wet side of optimum decreasing towards the wet side. Hydraulic conductivity generally decreased with increased dry density for all effort. Hydraulic conductivity increased with rice husk ash treatment at the OMC; but were within recommended values of 1 x 10-7 cm/s for up to 8% rice husk ash treatment irrespective of the compactive effort used. This shows the suitability of the material as a hydraulic barrier in waste containment systems for up to 8% rice husk ash treatment and beneficial reuse of this agro-industrial waste product.

Surface-positioned double-ring to improve traditional infiltrometer for measuring soil infiltration

Soil Research ◽  
2020 ◽  
Vol 58 (3) ◽  
pp. 314
Author(s):  
Jing Zhang ◽  
Shaopeng Li
Keyword(s):  
Hydraulic Conductivity ◽  
Measurement Accuracy ◽  
Soil Column ◽  
Saturated Hydraulic Conductivity ◽  
Experimental Results ◽  
Water Infiltration ◽  
Maximum Relative Error ◽  
Wetting Front ◽  
Double Ring ◽  
Improve Measurement

The installation of a traditional double-ring infiltrometer (DRI) into soil is difficult and time consuming. It results in reduced accuracy because of soil disturbance and water leakage along the gaps between the ring wall and the soil. In this study, a surface-positioned DRI (SPDRI) was suggested to improve measurement accuracy and convenience of the DRI. Laboratory experiments were conducted to evaluate performance of the method in terms of the influence of the lateral flow of water on the accuracy of infiltration rate, average vertical wetting front depth and saturated hydraulic conductivity. A cylindrical soil column was used to simulate the ideal ring infiltrometer (IRI) of the one-dimensional vertical infiltration process for comparison purposes. Experimental results indicated that the infiltration rates measured by the SPDRI and IRI were nearly identical, with maximum relative error (RE) of 18.75%. The vertical wetting front depth of the SPDRI was nearly identical to that of the IRI, with proportional coefficients of 0.97 and R2 > 0.95. Comparison of the soil saturated hydraulic conductivity with those from IRI indicated that the REs were 7.05–10.63% for the SPDRI. Experimental results demonstrated that the SPDRI could improve the measurement accuracy and facilitate the soil water infiltration measurement process.

scholarly journals Influence of bentonite type and producing method on hydraulic conductivity of sand–bentonite mixture

2020 ◽  
Vol 205 ◽  
pp. 10005
Author(s):  
Tomonori Sakita ◽  
Hideo Komine ◽  
Atsuo Yamada ◽  
Hailong Wang ◽  
Shigeru Goto
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Water Mass ◽  
Water Volume ◽  
Dry Density ◽  
Initial Water Content ◽  
Specimen Preparation ◽  
Initial Water ◽  
Compaction Energy ◽  
Low Level Radioactive Waste

Sand-bentonite mixtures with bentonite content of 10-30% had been planned to handle low-level radioactive waste in Japan, because of its low permeability. Hydraulic conductivity of sand–bentonite mixture depends on the bentonite type, bentonite content, initial water content, and other factors. Given this background, falling head permeability tests were conducted on sand–bentonite mixture by varying the compaction energy for specimen preparation, initial water content (10–20%), and bentonite content (15– 30%). For these tests, the hydraulic gradient of 25-500 was set. Consequently, the hydraulic conductivities were 10-8 – 10-13 m/s for all tested conditions. Correlation between the hydraulic conductivity and the effective montmorillonite dry density (montmorillonite mass divided by the sum of montmorillonite, air, water volume), which is often used to correlate the hydraulic conductivity of bentonite, was found. Correlation was also found between the hydraulic conductivity and a new index designated as the effective montmorillonite wet density (sum of montmorillonite and water mass / sum of montmorillonite, air, water volume). Effective montmorillonite wet density reveals differences in the specimen structural distribution through consideration of the initial water content.

scholarly journals Hydraulic characteristics of plow pan constructed sandy paddy soil by adding fly ash

2021 ◽  
pp. 993-1002
Author(s):  
Yang Wei ◽  
Nan Lu ◽  
Bo Yan ◽  
Gang Li
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Water Content ◽  
Paddy Soil ◽  
Storage Capacity ◽  
Water Storage ◽  
Saturated Hydraulic Conductivity ◽  
Wetting Front ◽  
Movement Rate ◽  
Water Storage Capacity

The feasibility of mixing fly ash to sandy soil to build the artificial plow pan of paddy soil in the Yellow River beach was explored. Water infiltration characteristics, saturated hydraulic conductivity, saturated water content and water storage capacity of the artificial plow pan were measured by using laboratory column tests. The results showed that under the same bulk density, when the amount of fly ash increased, the movement rate of the plow pan wetting front, the infiltration rate and the saturated hydraulic conductivity were decreased, then the water content and water storage of the soil layer increased. When the application amount of the fly ash was the same, and when the compaction weight decreased, the wetting front movement rate and saturated hydraulic conductivity increased and the soil water content and water storage capacity decreased. Mixing of fly ash with sand at a ratio of 1:3 (by weight) was found to be ideal for making an artificial of plow pan having bulk density of 1.7 g/cm3. Bangladesh J. Bot. 50(3): 993-1002, 2021 (September) Special  

Construction and monitoring of a composite soil cover on an experimental waste-rock pile near Newcastle, New Brunswick, Canada

1993 ◽  
Vol 30 (4) ◽  
pp. 588-599 ◽  
Author(s):  
Ernest K. Yanful ◽  
Michael D. Riley ◽  
Mark R. Woyshner ◽  
Jim Duncan
Keyword(s):  
New Brunswick ◽  
Water Content ◽  
Acid Production ◽  
Soil Cover ◽  
Waste Rock ◽  
Oxygen Flux ◽  
Dry Density ◽  
Rock Pile ◽  
Waste Rock Pile ◽  
Sand Base

A 130 cm thick composite soil cover was constructed on an experimental waste-rock pile at the Heath Steele mine site near Newcastle, New Brunswick. The cover consisted of a 30 cm thick sand base, a 60 cm thick compacted glacial till, a 30 cm thick granular layer, and a final 10 cm thick gravel layer for erosion protection. The till was compacted on the sand base in three finished lifts each of 20 cm thickness. Results of a preconstruction pad test indicated six passes of a 5-t vibratory compactor were required to attain the design specifications of 95% of the Modified Proctor maximum dry density at a moulding water content of 2–3% wet of the optimum. These compaction specifications also ensure that the till has a degree of water saturation of at least 95%, which is required to reduce oxygen and acid fluxes in the underlying pile. Quality control measures were taken during the construction to ensure the specifications were followed. Monitoring instrumentation was installed during the construction of the cover. Results indicate a reduction in gaseous oxygen concentrations in the pile from 20% before cover to about 3% after cover placement. The decreased oxygen penetration implies reduced oxygen flux and acid production. Volumetric water contents averaged about 32% in the till both immediately following cover installation and 7 months later. The water-content data are corroborated by soil-suction measurements. Temperatures in the pile have decreased following cover installation but appear to be more influenced by climatic variability than by a decrease in heat production and hence sulphide mineral oxidation. Observed discharge from two lysimeters, installed below the cover, indicates infiltration of 2–2.5% of precipitation during a 55-day period when rainfall was heavy. The quality of seepage from the pile has not changed since cover installation. Further monitoring will be required to confirm the reduction in acid production. Key words : waste-rock pile, acid generation, soil cover, suction, oxygen flux, percolation.

Hydraulic conductivity and consolidation response of mixtures of mine waste rock and tailings

2010 ◽  
Vol 47 (4) ◽  
pp. 472-485 ◽  
Author(s):  
Benjamin E. Wickland ◽  
G. Ward Wilson ◽  
Dharma Wijewickreme
Keyword(s):  
Hydraulic Conductivity ◽  
Acid Rock Drainage ◽  
Mine Waste ◽  
Waste Rock ◽  
Column Studies ◽  
Acid Rock ◽  
One Dimensional ◽  
Specimen Diameter ◽  
Dense Deposits ◽  
Mine Waste Rock

Hydraulic conductivity and consolidation behaviour are examined for an alternative mine waste disposal technique. One type of waste rock, one type of tailings, and mixtures of the same waste rock and tailings were tested in bench-scale and column studies. Specimens 150 mm in diameter were tested for hydraulic conductivity by falling-head method alternated with one-dimensional consolidation, specimens 300 mm in diameter were tested for one-dimensional consolidation response, and specimens 1 m in diameter were tested for self-weight consolidation behaviour in 6 m high columns. Deformation of mixtures under one-dimensional loading was similar to that of waste rock alone and much less than that of tailings alone. Hydraulic conductivity of mixtures was similar to that of tailings alone and independent of specimen diameter. Mixture behaviour was attributed to a homogeneous structure including waste rock in particle-to-particle contact and a continuous, saturated matrix of tailings. The results indicate that mixing waste rock and tailings can produce dense deposits with values of hydraulic conductivity that are orders of magnitude lower than those of waste rock alone, thereby limiting fluxes through the waste and the associated potential for acid rock drainage. Mixture deposits will also have less consolidation-related settlement than tailings, thus improving stability and aiding reclamation.

scholarly journals Laboratory-scale assessment of a capillary barrier using fibre optic distributed temperature sensing (FO-DTS)

2020 ◽  
Vol 57 (1) ◽  
pp. 115-126
Author(s):  
Robert Wu ◽  
Vincent Martin ◽  
Jeffrey McKenzie ◽  
Stefan Broda ◽  
Bruno Bussière ◽  
...  
Keyword(s):  
Water Content ◽  
Mine Waste ◽  
Volumetric Water Content ◽  
Temperature Sensing ◽  
Waste Rock ◽  
Coefficient Of Determination ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Capillary Barrier ◽  
Infiltration Test

Recent waste rock pile designs have been proposed to incorporate a fine-grained layer to create a capillary barrier to prevent surface water from draining into the pile interior. This study analyses active fibre optic distributed temperature sensing (FO-DTS) as a tool to measure the effectiveness a capillary barrier system following an infiltration test. A laboratory waste rock column was built with anorthosite waste rock overlain by sand. Volumetric water content is calculated during heat cycles lasting 15 min powered at 15 W/m in the column. A new algorithm is employed to circumvent several requirements for soil specific calibration. The inferred moisture contents were verified by soil moisture probes located adjacent to the cable. The FO-DTS data indicate, at vertical resolutions up to 2 cm, that water is retained in the sand and does not drain into the anorthosite following the infiltration test. The coefficient of determination, R2, between the inferred and measured volumetric water content in the fine cover sand layer is 0.90, while the screened anorthosite maintained an R2 of 0.94 with constant moisture content throughout the test. This study will ultimately help guide future waste rock storage design initiatives incorporating fibre optic sensors, leading to improved environmental mine waste management.

Expansive soil-biochar-root-water-bacteria interaction: Investigation on crack development, water management and plant growth in green infrastructure

2020 ◽  
pp. 105678952097441
Author(s):  
Hao Wang ◽  
Kexin Zhang ◽  
Lin Gan ◽  
Jiaqin Liu ◽  
Guoxiong Mei
Keyword(s):  
Hydraulic Conductivity ◽  
Plant Growth ◽  
Water Content ◽  
Hydraulic Properties ◽  
Biological Effects ◽  
Expansive Soil ◽  
Crack Development ◽  
Dry Density ◽  
Residual Water ◽  
Biochar Amendment

The objectives of the study are to explore fundamental mechanism of expansive soil-biochar-root-water-bacteria interaction, and investigate crack development and hydraulic properties of biochar amended soils aiming at green infrastructures. The physical, chemical and biological effects of biochar on expansive soil have been comprehensively explored. Crack development is investigated quantificationally, and mechanism of soil damage evolution is briefly discussed base on micro-chemical analyses. During outdoor vegetation period, photosynthesis light response curves were measured to evaluate plant growth. After period of vegetation, hydraulic properties of root-soil composites and unplanted soils were compared. The study reveals that soil crack intensity factor decreases by 33.5%, 48.5% and 47.3% due to 5%, 10% and 15% biochar introduction respectively after 5 wetting-drying cycles. 15% biochar amendment helps to restrain both initiation and propagation of soil cracks. Biochar amendment of up to 5% contributes well to residual water content and plant growth (i.e., light saturation point and light compensation point). Excessive biochar addition would restrain roots elongation, and increase saturated water content. Spatial root distribution is changed due to biochar addition, which further influences hydraulic properties and crack development. Hydraulic conductivity and soil dry density share negative correlations, 5% biochar enhances hydraulic conductivity remarkably at relatively loose condition. Biochar amendment also contributes to preventing nitrogen loss and forming more complex bacterial community in soils. The study adds to our knowledge of physio-chemical interactions of biochar with expansive clay, vegetation, water and microorganism.

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