Large Pits Research Articles

Productive Poplar Genotypes Exhibited Temporally Stable Low Stem Embolism Resistance and Hydraulic Resistance Segmentation at the Stem-Leaf Transition.

Breeding tree genotypes that are both productive and drought-resistant is a primary goal in forestry. However, the relationships between plant hydraulics and yield at the genotype level, and their temporal stabilities, remain unclear. We selected six poplar genotypes from I-101 (Populus alba) × 84 K (P. alba × Popolus tremula var. glandulosa) for experiments in the first and fourth years after planting in a common garden. Measurements included stem embolism resistance, shoot hydraulic resistance and its partitioning between stems and leaves, vessel- and pit-level anatomy, leaf carbon acquisition capacity, carbon allocation to leaves, and aboveground biomass (yield proxy). Significant genetic variations in hydraulic properties and yield were found among genotypes in both years. Productive genotypes had wide vessels, large thin pit membranes, small pit apertures, and shallow pit chambers. Hydraulic resistance was negatively correlated with yield, enabling high stomatal conductance and assimilation rates. Productive genotypes allocated less aboveground carbon and hydraulic resistance to leaves. Temporally stable trade-offs between stem embolism resistance and yield, and between hydraulic segmentation and yield, were identified. These findings highlight the tight link between hydraulic function and yield and suggest that stable trade-offs may challenge breeding poplar genotypes that are both productive and drought-resistant.

Nanoscale heterogeneities dictate corrosion pathways in a high-strength aluminum alloy

Micro-segregation and resulting nanoscale microstructural heterogeneities are unavoidable in wrought 7xxx aluminum alloys produced using current casting and thermomechanical processes. This study demonstrates that these nanoscale heterogeneities significantly impact pit growth in an extruded, age-hardened aluminum alloy 7075-T651. The alloy exhibits a complex microstructure with heterogeneously distributed E-Al18Mg3Cr2 dispersoids, which promote the precipitation of coarse ƞ-Mg(ZnAlCu)2 nanoparticles resulting in the formation of solute-depleted regions both within the grain interior and along the grain boundaries in dispersoid-rich areas. These alterations affect resistance to pit growth at the nanoscale, governing the transition of micro-galvanic sites into large pits with potential for crack initiation. This work underscores the necessity for modifying alloy composition and casting processes to develop superior aluminum alloys for critical applications.

Comparison of Corrosion Behavior of a-C Coatings Deposited by Cathode Vacuum Arc and Filter Cathode Vacuum Arc Techniques

This study explores the utilization of cathodic vacuum arc (CVA) technology to address the limitations of magnetron sputtering technology in preparing amorphous carbon (a-C) coatings, such as having a low ionization rate, low deposition rate, and insufficiently dense structure. Specifically, a-C coatings were prepared by the cathodic vacuum arc (CVA)and the filtered cathodic vacuum arc (FCVA) technology,, one with embedded carbon particles and one without, both having closely related carbon structures. Research is currently underway on bipolar plate coatings for fuel cells. The corrosion behavior of the prepared a-C coatings was examined through Tafel polarization analysis under simulated fuel cell operating conditions as well as potentiostatic analysis at 0.6 V under normal conditions and 1.6 V under start–stop conditions for 7200 s. The coatings before and after corrosion are characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and infrared spectroscopy. The results reveal that the incorporation of conductive graphite-like particles in the coatings reduces their contact resistance. However, the gaps between these particles and the coatings act as pathways for corrosive solution, exacerbating the corrosion of the coatings. After corrosion at 0.6 V, both sets of coatings with sp2-hybridized carbon structures are contaminated by elements such as hydrogen and oxygen, leading to an increase in their contact resistance. Under high potential conditions (1.6 V), large corrosion pits and defects appear at the locations of graphite-like carbon particles. Furthermore, both sets of samples exhibit more severe oxygen contamination and a transformation of broken carbon bonds from sp3- to sp2-hybridized forms, irrespective of whether embedded graphite particles are present.

Study on the coupling effect and construction deformation control of large deep foundation pit groups involving iron considering the coupling effect of seepage stress

Due to factors such as groundwater seepage and soil stress coupling effect, significant deformation and instability problems often occur during the construction process of super large deep excavation groups involving iron, seriously affecting the safety and stability of the project. This article aims to explore the coupling effect of super large deep excavation groups involving railways during the construction process, and how to effectively control construction deformation. This article combines theoretical analysis and numerical simulation to study the coupled effects of seepage and stress during the construction process of super deep excavation groups involving iron. With the help of finite element software, a numerical model of a large and deep excavation group involving iron was established, and the deformation and stress distribution at different construction stages were simulated. The research results indicate that the coupling effect of groundwater seepage and soil stress has a significant impact on the deformation and stability of the super deep excavation group involving iron. Therefore, reasonable construction measures and deformation control methods should be taken during the construction process.

Bird Nuisance at an Oil Gathering Station: A Landscape and Site Analysis

Abstract Barn swallow (Hirundo rustica) is a migratory bird. In Petapahan Gas Station (GS), Riau, this bird roost in a big number and create some nuisance due to their faeces. The objective of this paper was to analyse the possible causes of swallow’s roost behaviour at the landscape and site level, and formulate some recommendations. Migratory bird route was studied, the surrounding areas was analysed using, and characteristics of the GS was observed. Petapahan happened to be located at the known bird migratory route. The land-use of surrounded areas was a vast area of oil-palm plantation mixed with agricultural-area, open-area, and housing, create an excellent habitat for insects as the bird’s food. There was no other alternative for roost-site in the 5km radius. At the GS there are many large pipes, small pipes, handrails, I-beams, C-beams, valves, flares, big tanks, pits, office, and many other instruments that can function as the barn swallow’s roost site. Warm temperature, sufficient lighting, and safety from predator also provided good support. Basically, the GS has to accept the occurrence of the birds, while employing some management actions: (1) setting zonation for bird-free and bird-tolerance areas, and (2) put netting and other bird deterrent sensitive sites.

Corrosion behavior of SMSS 13Cr and SS 316L under chloride solution and H2S/CO2 environments

Abstract Corrosion resistant alloys (CRAs) include a range of different stainless steels and nickel alloys that are used in corrosion-aggressive environments encountered in oil and gas operations. Supermartensitic stainless steel (SMSS 13Cr) has been used in the manufacture of steel tubes for use in oil drilling due a more financially viable option to replace the austenitic stainless steel (SS 316L) in the oil and gas market. This present work estimate the effect of the hydrogen sulphide (H2S) on SMSS 13Cr and SS 316L, in saline solution, simulating the operating conditions in the oil and gas industry. Corrosion behavior was monitored using Potentiodynamic-Potentiostatic-Potentiodynamic (PD-PS-PD) technique in order to obtain pitting potential (Ep) or crevice potential (Ecrev)) and repassivation potential (Erp) while the long-term Open Circuit Potential (OCP) technique was applied to estimate the stable corrosion potential (Ecorr*). A Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) and Optical Microscopy were used for surface characterization. With all analysis carried out was possible to propose a trend regarding the pitting probability. The pitting increases with increasing H2S concentration on SSSM 13Cr, consequently, large, and deeper pits were observed, making possible to develop into cracks if there are mechanical stresses. On the contrary, the pitting probability for the SS 316L is low (compared with SMSS 13Cr) for all environments reproduced here in this research.

Xianyuechelys yingliangi: a new nanhsiungchelyid turtle from the Late Cretaceous of Ganzhou Basin, China

Nanhsiungchelyidae is a group of large Pan-Trionychia that lived in North America and Asia during the Cretaceous. Despite a long research history, their taxonomy and internal nodes are still controversial. Here, we erect a new taxon, Xianyuechelys yingliangi gen. et sp. nov., from the Upper Cretaceous Lianhe Formation of Ganzhou Basin, China. Xianyuechelys yingliangi is attributed to Nanhsiungchelyidae based on its carapace being covered by a sculpturing of large pits. However, the new species also possesses an unique combination of characteristics among nanhsiungchelyids such as a wide, crescentic nuchal, absence of a pair of anterolateral processes, and the fourth and fifth vertebral scutes that contact at a point. The holotype is a juvenile or sub-adult based on the incomplete ossification of carapace, but its morphological characteristics can mostly be regarded as taxonomically informative rather than ontogenetic in origin. Phylogenetic analysis suggests Xianyuechelys yingliangi forms a monophyletic group with Nanhsiungchelys spp. and Anomalochelys angulata, supported by two unambiguous synapomorphies: wide vertebral scutes and wide neurals. The phylogenetic analysis also suggests Basilemys, Jiangxichelys and ‘Zangerlia’ form a monophyletic group. Our new finding increases the known diversity of nanhsiungchelyids in southern China. http://zoobank.org/urn:lsid:zoobank.org.pub:3440EEB0-D38A-4275-8486-48ABAA274B47

Effect of laser and coating surface treatment on the bond strength of zirconia ceramics.

This study aims to investigate bond strength between zirconia and resin cement through surface treatments with Er: YAG laser, Nd: YAG laser, and Si-Zr coating. Seventy-five round pre-sintered zirconia discs with a diameter of 18 mm and a thickness of 1.5 mm were prepared by a powder compactor. Fifty discs were randomly divided into five groups of 10 discs each and were subjected to five surface treatments: no treatment (control group), sandblasting with alumina particles (sandblasting group), Er: YAG laser treatment (Er: YAG laser group), Nd:YAG laser treatment (Nd: YAG laser group), and Si-Zr coating treatment (Si-Zr coating group). The discs were then bonded to composite resin columns with resin cement. The shear bond strength of each group was tested with a universal tester. Roughness tester, scanning electron microscope (SEM), and energy dispersive spectroscopy were used to analyze surface performance. The bond strength of the Si-Zr coating group was higher than that of the remaining groups (P<0.05). The difference in bond strength between the sandblasting group and the Er: YAG laser group was not statistically significant (P>0.05), but both of them had higher bond strength than the Nd: YAG laser group (P<0.05). The Si-Zr coating group had the highest surface roughness (P<0.05). The surface roughness of the sandblasting, Er: YAG laser, and Nd: YAG laser groups was higher than that of the control group (P<0.05), but the difference among the three groups was not statistically significant (P>0.05). SEM observations showed irregular scratches on the surface of the sandblasting group and large pits with holes on the surface of the Er: YAG and Nd: YAG laser groups. In the Er: YAG laser group, the crystal structure was replaced by a smooth surface with a large amount of microcracks due to partial melting. Complex porous structures that comprised "island-like" structures and mass pores among the grains were observed on the surface of the Si-Zr coating. Only Zr, O, and Y were detected on the surfaces of the control, Er: YAG laser, and Nd: YAG laser groups. Al was found on the surface of the sandblasted group, and a higher proportion of Si was detected on the surface of the Si-Zr coating group. Er: YAG laser and Nd: YAG laser treatment on the zirconia ceramic surface could increase roughness and improve the bond strength to resin cement. Si-Zr coating treatment is an effective alternative for increasing the roughness and bond strength of zirconia surface and is superior to sandblasting and laser treatments.

Data acquisition method for digital construction site of large foundation pit engineering

To ensure the construction safety of large foundation pit engineering (FPE) and optimize the data collection method, this paper applies sensors and automatic collection items to automatic data collection based on traditional manual measurement. Data processing and analysis are carried out through the large FPE detection system construction. In the early warning module, the improved Grey Model (GM) (1,1), namely the improved method G, is used to predict the settlement of buildings around the monitoring project, and its reliability is analyzed. The improved method G has a good test result. Compared with method G and the Autoregressive Integrated Moving Average model (ARIMA), the improved Method G has a better prediction effect and smaller prediction error. When compared with method G, the mean absolute error (MAE) of the method used in the paper is smaller, which is −0.01. The root mean square value of absolute error is smaller, which is 0.0.54 less than method G. Compared with the ARIMA model, the average RE of the method used in this paper is 3.97%, which is 0.05% less than that. This method can be used to collect and predict data on large foundation pit (FP) construction sites, which is conducive to ensuring construction safety.

Regulation of mitochondrial network architecture and function in mesenchymal stem cells by micropatterned surfaces

Abstract Mitochondrial network architecture, which is closely related to mitochondrial function, is mechanically sensitive and regulated by multiple stimuli. However, the effects of microtopographic cues on mitochondria remain poorly defined. Herein, polycaprolactone (PCL) surfaces were used as models to investigate how micropatterns regulate mitochondrial network architecture and function in rat adipose-derived stem cells (rASCs). It was found that large pit (LP) induced rASCs to form larger and more complex mitochondrial networks. Consistently, the expression of key genes related to mitochondrial dynamics revealed that mitochondrial fusion (MFN1 and MFN2) and midzone fission (DRP1 and MFF) were increased in rASCs on LP. In contrast, the middle pit (MP) enhanced mitochondrial biogenesis, as evidenced by the larger mitochondrial area and higher expression of PGC-1. Both LP and MP promoted ATP production in rASCs. It is likely that LP increased ATP levels through modulating mitochondrial network architecture while MP stimulated mitochondria biogenesis to do so. Our study clarified the regulation of micropatterned surfaces on mitochondria, highlighting the potential of LP and MP as a simple platform to stimulate mitochondria and the subsequent cellular function of MSCs.

Effects of deoxidation methods on the inclusion characteristics and corrosion behaviour of high-strength low-alloy steels in marine environments

The effects of deoxidation methods on the inclusion characteristics and corrosion behaviour of high-strength low-alloy steels were examined in marine environments using various microcharacterisation techniques and first-principles calculations. After Ca treatment, MnS–MgO–Al2O3 inclusions were modified to CaS–MgO–Al2O3 and microcrevices were existed at the interface between inclusions and Fe. After Zr–Ti-RE deoxidation, spherical CaS + TiN + ZrO2+MgAl2O4+(Ca, La) Al3O7 inclusions appeared. (Ca, La)Al3O7 in steel displayed similar mechanical properties to Fe, reducing the degree of lattice distortion and the formation of microcrevices around the inclusions. Micro-galvanic corrosion between Fe and MnS accelerated the localised corrosion rate and promoted the formation of large pits on the surface. However, the chemical activity of CaS resulted in dissolution of the inclusion, which relatively inhibited the localised corrosion propagation. The enrichment of Cr in the rust layer after Zr–Ti-RE deoxidation improved the compactness, contributed to a reduction in the localised corrosion rate and long-term corrosion rate. Finally, the underlying mechanism influencing corrosion behaviour was established.

Stretched sapwood, ultra-widening permeability, and ditching da Vinci: revising models of plant form and function.

The mechanisms leading to dieback and death of trees under drought remains unclear. For constructing an understanding of these mechanisms, addressing major empirical gaps regarding tree structure-function relations remains essential. We give reasons to think that a central factor shaping plant form and function is selection favoring both constant leaf specific conductance with height growth and isometric (1:1) scaling between leaf area and the volume of metabolically active sink tissues ("sapwood"). Sapwood volume-leaf area isometry implies that per-leaf area sapwood volumes become transversely narrower with height growth; we call this "stretching." Stretching means that selection must favor increases in permeability above and beyond that afforded by tip-to-base conduit widening (ultra-widening permeability), as via fewer and wider vessels or tracheids with larger pits or larger margo openings. Leaf area-metabolically active sink tissue isometry would mean that it is unlikely that larger trees die during drought because of carbon starvation due to greater sink-source relationships as compared to shorter plants. Instead, increase in permeability is most plausibly associated with greater risk of embolism, and this seems a likelier culprit of the preferential vulnerability of larger trees to climate change-induced drought. Other implications of selection favoring constant per-leaf area sapwood construction and maintenance costs are departure from the da Vinci rule expectation of similar sapwood areas across branching orders, and that extensive conduit furcation in the stem seems unlikely. Because all of these considerations impact the likelihood of vulnerability to hydraulic failure versus carbon starvation, both implicated as key suspects in forest mortality, we suggest that these predictions represent essential priorities for empirical testing.

Mechanism of local hydrogen entry into Fe sheets induced by atmospheric corrosion: Significance of potential, pH, and rust layer thickness

Local hydrogen entry under a NaCl droplet on Fe sheets was analysed by employing a hydrogenochromic sensor and electrochemical hydrogen permeation tests. Large crystallographic pits barely promoted hydrogen entry, because crystallographic pitting proceeded at potentials higher than the potential of the hydrogen evolution reaction. Hydrogen entry was accelerated because of acidification under an island-like rust layer. The rust layer became thick in its outer regions, mainly owing to severe corrosion and alkalisation around the rust-formed area. Hydrogen entry was prominent under the thick rust layer after disappearance of the droplet, owing to the high concentrations of chloride ions and protons.

A fifth‐ to sixth‐century CE lynx (Lynx lynx L., 1758) skeleton from Hungary 2: Stature and archaeological interpretations

AbstractLynx remains are rare in archaeological assemblages. The skeleton of an adult male accompanied by four dogs was found in a large Migration Period pit at Zamárdi–Kútvölgyi‐dűlő II, Hungary. Extant lynx skeletons were used in estimating the shoulder height of this individual. Its stature is comparable to those of the large dogs it was buried with. None of the five skeletons showed skinning marks. Although the physical reconstruction of the lynx was of help in appraising this special pit, the actual nature of the deposit remains in question. Possible interpretations range from the mundane discard of carcasses to the poorly understood ritual burial of carnivores, beginning with the lynx. We reviewed these options within the framework of cultural diversity of Migration Period peoples in west‐central Hungary.

Erosion-corrosion failure analysis of the elbow pipe of steam distribution manifold

This work discusses a case study of the failure of rice condition plant boiler pipe fittings. The failure analysis was performed on the 45° and 90° API 5LX65 steel pipe elbows connected to a steam manifold in a boiler of a rice conditioning plant. Failure analysis was performed by visual observation, microscopic analysis, hardness measurements, and numerically by Computational Fluid Dynamics (CFD). It was confirmed that the mechanism of failure was due to erosion-corrosion. The results showed also that, erosion-corrosion at the outlet of the 90° and 45° elbows due to the maximum particle impact in the high pressure and high turbulence intensity region. Microscopic analysis of the 90° and 45° elbows showed that large pits and cuts were the main reason for leakage perforation. Erosion at the inner bend of the 90° and 45° elbows is lower than at the outer bend, which is related to the higher particle–wall impaction, pressure, and turbulence intensity. The main cause of leakage and wall thinning in both elbows is the development of limescale which leads to pitting corrosion and the formation of leaks at higher oxygen concentrations. The simulation results show that the maximum material removal rate in the 45° elbow is 42 % lower than in the 90° elbow, the erodent impaction and higher wall shear are liable for the development of the perforation near the exit of 90° and 45° elbows.

Observations of Atmospheric Corrosion Testing on Heated Austenitic Stainless Steel Surfaces: Exploring the Role of Inert Dust Particulates and Seawater

Relevant atmospheric corrosion laboratory testing environments were developed to explore the influence of inert dust and seawater on the corrosion susceptibility of stainless steel in spent nuclear fuel dry storage conditions. Measurements from dust collected on in-service dry storage canisters were applied to develop exposure conditions. Three atmospheric exposure conditions, two static and one cyclic, were examined with three different surface coverages: co-deposited large dust and seawater, co-deposited small dust and seawater, and solely seawater. Stainless steel coupons representative of spent nuclear fuel dry storage canister material were subjected to the various corrosion environments, with the results from exposures up to 1 year presented here. Post exposure, corrosion damage was analyzed using optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Initial observations are presented herein, and potential implications with respect to the influence of inert dust particles on corrosion susceptibility are summarized. In general, the co-deposition of dust and salt resulted in larger pits and exhibited mixed modes of corrosion that were not observed in the no-dust conditions (i.e., crevicing, filiform, and pits within pits). The presence of the inert dust may influence brine spreading and/or act as crevice formers, leading to enhanced corrosion. This study highlights the significance of incorporating dust particulate(s) beyond the deliquescent chemistries to fully evaluate atmospheric corrosion severity.

Complex dental wear analysis reveals dietary shift in Triassic placodonts (Sauropsida, Sauropterygia)

Placodonts were durophagous reptiles of the Triassic seas with robust skulls, jaws, and enlarged, flat, pebble-like teeth. During their evolution, they underwent gradual craniodental changes from the Early Anisian to the Rhaetian, such as a reduction in the number of teeth, an increase in the size of the posterior palatal teeth, an elongation of the premaxilla/rostrum, and a widening of the temporal region. These changes are presumably related to changes in dietary habits, which, we hypothesise, are due to changes in the type and quality of food they consumed. In the present study, the dental wear pattern of a total of nine European Middle to Late Triassic placodont species were investigated using 2D and 3D microwear analyses to demonstrate whether there could have been a dietary shift or grouping among the different species and, whether the possible changes could be correlated with environmental changes affecting their habitats. The 3D analysis shows overlap between species with high variance between values and there is no distinct separation. The 2D analysis has distinguished two main groups. The first is characterised by low number of wear features and high percentage of large pits. The other group have a high feature number, but low percentage of small pits. The 2D analysis showed a correlation between the wear data and the size of the enlarged posterior crushing teeth. Teeth with larger sizes showed less wear feature (with higher pit ratio) but larger individual features. In contrast, the dental wear facet of smaller crushing teeth shows more but smaller wear features (with higher scratch number). This observation may be related to the size of the food consumed, i.e., the wider the crown, the larger food it could crush, producing larger features. Comparison with marine mammals suggests that the dietary preference of Placochelys, Psephoderma and Paraplacodus was not exclusively hard, thick-shelled food. They may have had a more mixed diet, similar to that of modern sea otters. The diet of Henodus may have included plant food, similar to the modern herbivore marine mammals and lizards.

Three-stage degradation behavior and dealloying assisted galvanic corrosion mechanism of 300 MPa grade Zn-2Cu-xLi (x = 0.2-0.8) alloys in simulated body fluid

Corrosion behaviors of biodegradable Zn alloys with ternary phases are rarely studied. This paper reveals three-stage corrosion behavior of high-strength Zn-2Cu-(0.2–0.8)Li alloys immersed in simulated body fluid for 30 days. At stage Ⅰ, Zn phase is preferentially corroded due to cathodic Zn-Cu-Li ternary phases recently identified. At stage Ⅱ, corrosion is suppressed due to formation of protective layer containing LiOH and Li2CO3 with appropriate Pilling-Bedworth ratios. At stage Ⅲ, dealloying of Zn-Cu-Li phases rises their Cu contents, accelerating galvanic corrosion and resulting in large pits beyond 200 µm.

Study of the Mechanical Behavior of Retaining Structures and Adjacent Buildings during the Excavation of Deep and Long Pits

Excavation of deep and long pits can cause strata deformation and settlement of adjacent buildings. The excavation of a deep foundation pit of a nearby building in Zhengzhou City, China, is taken as the research object. The foundation of the foundation pit is an independent foundation under the column, the depth of the foundation pit is 24.5∼26.3 m, and the support form of an underground continuous wall and four internal supports is adopted. The stress and deformation characteristics of retaining structures during the construction of deep and long pits and their impact on the deformation of nearby buildings were studied through on‐site monitoring and finite element simulation. The analysis focuses on the effects of different excavation stages on adjacent structures, with the main conclusions as follows. After excavation, the underground continuous wall far from the building undergoes a “rotating‐kick” displacement, while the underground continuous wall on the side near the building only shows a “kick” displacement. Adjacent buildings have little influence on the distribution of shear force and bending moment of the underground continuous wall of the foundation pit. The first horizontal strut experiences pressure, gradually shifting to tension as excavation continues, with the maximum stress reaching 3.6 × 103 kN. The second, third, and fourth horizontal struts mainly bear compressive forces, increasing with the depth of the struts. The building primarily undergoes settlement in the early stages of deep and long pit excavation. As the excavation progresses, the building points near the pit begin to bulge, but the building corners far from the pit continue to show settlement. During the excavation of the deep and long pit, the differential settlement of the long side of the nearby building first decreases and then increases, and the differential settlement of the short side changes from a slight decrease to a significant increase. The settlement evolution of the building is as follows: overall settlement ⟶ overall uplift ⟶ uplift of the side of the building near the pit ⟶ outward tilting away from the pit. The findings may provide references for designing, constructing, and operating deep and large foundation pits.

Groundwater and surface water control at Highland Valley copper mine (HVC) (in rock and soil both)

This paper is about dewatering of the two large open pit porphyry copper-molybdenum mines of Highland Valley Copper in BC, Canada. These two pits occur within the well differentiated Guichon Creek Batholith with phases progressively more acidic and coarser grained towards the center and intersected by intense fracturing within the ore bodies and also concentric alteration haloes. Also, they are both cut by the steeply dipping Lornex fault which is an average 155 m wide faulting zone with frequent sympathetic faults adjacent to it. As the two pits have mined down at depth, they have exposed bedrock especially with frequent toppling-type faults and shears which have exhibited varying degrees of toppling and ravelling of the pit walls. Also, on the east wall of the Valley Copper pit, there is up to about 350m of glacio-fluvial overburden, originally with artesian flows in two or three aquifers. The toppling is exacerbated by the hydrostatic pressure of the groundwater in the pit walls. Both pits have significant groundwater and run-off in the spring. In order to be able to continue mining down to depths of about 600 to about 750 meters it has been necessary to de-water the walls and divert the surface run-offs to prevent infiltration into the toppling faults. So two water diversion projects were necessary at the crest of the highwalls and were completed to drain both by gravity and pumping the spring run-off water away from the two pits. Also, a major well drilling project is ongoing in the glacio-fluvial overburden aquifers to dewater them with upwards of 4500 US gpm flows. In addition, an annual series of horizontal drainholes were drilled and are ongoing approximately every three benches to dewater and depressurize the bedrock. Minor bedrock wells in the crest of the Lornex Pit also contribute to the dewatering. All the dewatering has allowed the two pits to mine down to close to design depths without significant disruption.