Abstract: Primary waste containers are placed in prefabricated canisters and sealed with a curable fluid sealant, such as grout. The canisters are then stacked in an interlocking manner to form a stable integrated structure. The containers are not, however, permanently attached to one another, so that individual containers are able to shift relative to one another in response to earth movements. In this way, the integrity of the individual container is maintained and the sealed wastes protected even when the integrated structure as a whole experiences significant stresses from earth movement.

Abstract: A system and method for treating biodegradable waste which includes a land treatment area surrounded by dikes and underlain by an impermeable layer. A leachate collection system, with a pre-determined slope and an underdrain system, overlies the impermeable layer. The leachate collection system permits the collection of effluent which is routed to a wastewater treatment system. Surface water is removed by an exterior drainage system.

Abstract: An elastomeric sealing device to prevent ingress of surface fluids into holes, principally drains which are characterized by non-watertight covers or grilles with either regular or irregular topographic boundaries. The device comprises a three-part construction, including a top film, a core elastomer having minimal shear strength, and a bottom film. When in use, the device conforms to contour of adjacent hole covering device and fills existing crevices and voids, thereby providing an efficient seal. When removed from hole, device recovers neutral shape thereby being suitable for re-use on same or different hole.

Abstract: Apparatus for lining an irrigation canal with a sheet of fiber-reinforced plastic includes structure for depositing a layer of resin and fiber on a web of flexible carrier material, partially curing the resin prior to laying the sheet in the canal, and then laying the sheet in the canal while the resin is flexible enough to conform to the shape of the canal. The final curing of the resin takes place after the sheet is placed in the canal. A predetermined-shape wrinkle is induced in the carrier web before it is laid into the canal to assist in conforming the sheet to the canal shape without causing randomly placed wrinkles so that the sheet is smooth in the canal. The apparatus forms the sheet and is propelled so that it travels along the length of the canal, fabricating a continuous sheet as it travels. In one embodiment the carrier is a flexible but nonelastic material like kraft paper, coated on one side with wax or other film to prevent saturation by the resin.

Abstract: A fuel delivery system for a filling station provides a membrane which is formed as a continuous basin associated with at least one bulk storage tank and at least one remote delivery pump for dispensing the fuel upon demand with a plurality of pipes interconnecting the tank and the pump. The membrane at least partially surrounds the tank, completely surrounds the pipes, and extends under the pump for collecting any fuel spills or leakage. The earth or ballast supporting the membrane is graded to drain all collected fluids into a collection area, from which it may be pumped away. The membrane is under single walled fuel tanks and over double walled tanks. A frame supports the membrane above the tank while ballast is being packed around it.

Abstract: A seal for connecting abutting first and second elastomeric sheets having overlying metallic portions including an elastomeric strip. The elastomeric strip is bonded to the elastomeric portions of the first and second sheets. A metallic plug is attached to the metallic portion of the abutting sheets and is itself covered by a layer of flexible and abrasion resistant material which adheres to the metallic plug and the metallic portions of the abutting sheets.

Abstract: Stable, gel-forming aqueous microemulsions, well adopted for the reversible stabilization or plugging of soil/rock formations, e.g., subterranean well formations, are comprised of (i) an aqueous solution of a water-soluble alkali metal silicate, (ii) a gelling reagent therefor, and (iii) at least one surface active agent.

Abstract: The present invention relates to a method for improving the mechanical properties of soil. The method uses an aqueous solution of a sulfonated urea melamine formaldehyde resin and a water soluble polyvinyl alcohol having a molecular weight between 40,000 and 120,000. The aqueous solution is sprayed onto the surface of the soil.A number of water soluble compositions which include a sulfonated urea melamine formaldehyde resin and polyvinyl alcohol and methods for making the same are also disclosed.

Abstract: A method of constructing a means suitable for directing or holding water is described. A depression suitable to direct, transport, or hold water, such as a water catchment or irrigation ditch is covered with cloth, any seams are fastened together, then the cloth is coated with a liquid silicone elastomeric composition curable at atmospheric conditions. The coated cloth edges are stabilized. The method yields a depression having a surface impervious to liquid water that has a long expected life due to its resistance to damaging effects such as weathering and exposure to wandering animals.

Abstract: The present invention relates to a method of waterproofing using a layered water sealing article of manufacture including a layer of a flexible sheet material adhered to a layer of a composition comprising a non-hydrated water-swellable clay intimately contacted with a polypropene, polybutene, or mixtures thereof. The water swellable clay composition can be adhered to the flexible sheet material in any manner, such as by extruding the composition in sheet form onto a layer of sheet material. The clay composition layer is sufficiently tacky to adhere to the sheet material on one major surface, and is sufficiently tacky for adherence to a wall or conduit, floor or roof on an exposed major surface in areas of potential water flow to prevent the seepage of water through the bentonite clay composition layer.

Abstract: This is a method and apparatus for the collection and utilization of environmental water in remote locations wherein the invention features the utilization of dome-protected water collection reservoirs suitable to collect rain in major or minor amounts, evaporative moistures such as dew, fog and the like. The invention is characterized by the utilization of a trough-like member having a dome-like cover to prevent undue evaporation and wherein the dome cover is provided with access ports such that animals can obtain water from the collected water. Alternately, the dome covering may be omitted and a conduit provided from the trough to another non-evaporative container.

Abstract: Fluid leakage through soil in a region thereof is controlled by sequentially passing over the region to dig a plurality of parallel, laterally displaced grooves in the surface. Soil dug from each groove is temporarily stored, and a strip of sheet material is laid over a groove as it is created during each pass, the width of the strip being greater than the width of the groove. Thereafter, the temporarily stored soil is deposited on the strip such that it is covered with soil except along one edge, the other edge of the strip overlying the uncovered edge of an adjacent strip laid down during a previous pass over the region. As a consequence, a first layer of overlapping strips of sheet material covered with soil is installed over the region.

Abstract: Disclosed is an underground waste barrier structure that consists of waste material, a first container formed of activated carbonaceous material enclosing the waste material, a second container formed of zeolite enclosing the first container, and clay covering the second container. The underground waste barrier structure is constructed by forming a recessed area within the earth, lining the recessed area with a layer of clay, lining the clay with a layer of zeolite, lining the zeolite with a layer of activated carbonaceous material, placing the waste material within the lined recessed area, forming a ceiling over the waste material of a layer of activated carbonaceous material, a layer of zeolite, and a layer of clay, the layers in the ceiling cojoining with the respective layers forming the walls of the structure, and finally, covering the ceiling with earth.

Abstract: The invention process for installing an overliner membrane begins with preparing a site by digging a pit for the installation of fuel tanks, for example, which may be associated with leakage or spillage of fluids. Then, ballast is packed under and around the tanks to support and stabilize their position, the ballast rising to a level which is above the tanks but below points where the leakage or spillage may occur. Next, a frame is built over the ballast in the area where the leakage or spillage may occur. A membrane is spread across the surface of the ballast and attached to the frame in order to form a basin in which this leakage or spillage may collect. The frame and the membrane are completely covered with ballast in a manner which maintains the side walls of the membrane in a vertical position. A trench system for delivery pipes carrying fuel from the tank to outlying locations contains a trench liner membrane which surrounds the pipes and drains into the membrane basin.

Abstract: A soil injection agent on an alkali metal silicate basis, containing as gelling agent trialkoxysilanes of the formula R-Si(OR').sub.3, in which R is an aliphatic moiety of 1 to 6 carbon atoms and R' represents equal or different alkyl moieties of 1 to 4 carbon atoms, is adjusted for properties by the addition of acid alkali metal phosphates or ammonium phosphates and/or phosphoric acid. The addition improves the sealing and strengthening action of the gels and permits a reduction of the silane content, without impairing the resistance of the gels to pollutants.

Abstract: Sealing and/or stabilizing and/or binding preparations comprising modified alkali metal silicate solutions having a molar ratio of SiO.sub.2 to Me.sub.2 O of from 2 to 4.5 wherein Me represents sodium or potassium; sodium metaborate and/or potassium metaborate in a molar ratio of SiO.sub.2 to B.sub.2 O.sub.3 of from 5 to 400; and glyoxal, and to the use of these preparations.

Abstract: A sheet of material is laid in the ground by digging a trench in the ground by means of a trench digger and unwinding the sheet of material from a stock roll above ground level, passing it into the trench in a downward direction and diverting it in a direction essentially parallel to ground level. In order for the protective housing which is attached downstream of the trench digger and has to keep the trench open over its length not to be designed too long the sheet of material is passed into the trench folded double and is unfolded via three return rollers or rods or flanges, and passed in the unfolded state in an approximately vertical plane in the horizontal direction.

Abstract: A method and apparatus are provided for constructing a deep essentially horizontal borehole in the earth, as for the installation of a pipeline in Arctic offshore waters. This directional drilling technique eliminates exposure of an Arctic offshore pipeline to ice gouging and minimizes the hazards associated with unstable permafrost. Means are provided for gripping inside a borehole in order to apply thrust to a drill bit utilized to drill the borehole which is to contain the pipeline.

Abstract: A basemented floor structure under a waste dump, whereby the burden of the waste body is transferred to piers and then onto foundations and the subgrade, and on which layers of sealing material, drainage material or protective material lie, is built up from individual support elements separated from one another by seams and having an upwardly convex or concave shape. By this structure, unequal setting of the subgrade can be accommodated without harm and cracks in the floor structure are prevented. The upper surfaces of the support element are inclined toward the piers. The seepage is taken from collecting zones through a water removal system to a purification plant.

Abstract: A method and apparatus for the subsequent underground sealing of an area, preferably of dumps. With the method, it is possible to seal dumps underground. Working pipes are introduced from a region outside a dump body. The region of soil between the working pipes is loosened, and sealing material is then introduced into this region, which solidifies to become a sheet-like sealing compound. With this method, in particular existing dump bodies can be sealed subsequently underground, without having to drill through the dump body. The apparatus for carrying out the method has a loosening device, and a feed device for the sealing material. The two devices are able to move in the region between two adjacent working pipes.

Abstract: An improvement was provided in the method for forming a water-impermeable layer in a sandy soil by sprinkling an aqueous solution containing a water-soluble polymer, e.g. poly(acrylic acid), over the land so as to infiltrate the soil with the solution, according to which the water-impermeable layer can be formed at a controlled depth as desired from the ground surface by controlling the value of pH of the aqueous polymer solution in the range from 4 to 12.

Abstract: A secondary containment system which may be manufactured in a factory, shipped and installed in a reasonably low cost and fully usable manner. In one embodiment, a large membrane of material, completely lines a collection and containment pit along with radiating trenches which drain into the collection pit. There is substantial amount of membrane bulk which enables it to bunch in the corners and to provide slack which conforms to irregularities on the earthen walls and floor of the pit. Thus, localized stresses do not occur at places where the membrane bridges protections formed on the walls, in the corners, or the like. In another embodiment, the membrane covers a tank in the pit and drapes down to form deep areas where liquids may collect. A perimeter steel cable surrounds the hole. The membrane is attached to this cable so that the membrane is mechanically strong enough to meet the shoring requirements of the various occupational safety laws.

Abstract: An economical method of constructing a means suitable for directing, transporting, or holding water based upon the use of an aqueous liquid silicone elastomeric emulsion to form a membrane on a depression surface which is suitable to direct, transport or hold water. The emulsion, which cures under atmospheric conditions, is sprayed on the depression surface, then dried. The construction is useful as a water harvesting structure with a long, useful life. Such structures are particularly useful in providing water for animals in arid regions.

Abstract: A liner or cover system is provided, which can at times have at least a portion of its area exposed to wind and/or ground fluid action and consequent damage, and which is held in position against dislodgement and therefore against damage by said action by an anchoring means or structure. The system is held anchored from under it at a plurality of loci by said anchoring means or structure which exerts at each said loci a force at least equal to the maximum force of wind and/or ground fluid expected to act at any time at said loci independently from any force acting at any time at any other of said loci of said liner or covering.

Abstract: A gel-forming composition is provided comprising a PVA based substance selected from the group consisting of a polyvinyl alcohol, a polyvinyl alcohol copolymer, and mixtures thereof, aldehyde, and water. The gel-forming compositions are preheated to effect a predetermined amount of partial crosslinking of the PVA based substance and the aldehyde thereby enabling a lower aldehyde concentration to be used which in turn produces a more stable gel. The gel-forming compositions are useful for retarding the flow of fluids in subterranean formations. For example, for retarding the flow of water in high permeability channels in oil reservoirs. The gels and method of use herein provided are particularly useful in waterflood operations to increase the sweep efficiency of the oil recovery process.

Abstract: A method of controlling subterranean placement of underground fluids, such as liquids, includes(a) positioning a tubing joint longitudinally in a borehole in the earth to locate the split and gun at selected depth,(b) rotating the tubing to orient the split azimuthally so that a gun in the tubing is aimed in a desired direction laterally,(c) discharging the gun to cause its projectile to travel in said desired direction in the formation, thereby opening up a lateral shot hole in the formation,(d) and pumping fluid under pressure down the borehole to discharge into the shot hole into a selected zone laterally spaced from the tubing.

Abstract: There is provided a process for rendering certain layers impervious to the seepage of water through same. Such layers are of value in preventing water seepage into structures, and also from ponds, from water reservoirs and the like. The water impervious layers are produced from mixtures of sand (about 98.5 to 90 weight percent) and montmorillonite (about 1.5 to 10 weight percent), which are compacted and contacted with salt water having a salt content at least equal to that of sea water, and washing the layer until the wash waters are essentially free of sodium.

Abstract: Liquid or water-soluble pollutants which have entered into permeable soil strata are prevented from spreading and contaminating ground water by surrounding the contaminated zone on all sides with vertical barriers and closed off at the bottom by a horizontal injected floor which seals not only against water but also against the pollutants. The pollutant resistance of the floor is achieved by the use of injection materials on a silicate basis containing trialkoxysilanes of the general formula R-Si(OR').sub.3.

Abstract: A method of controlling subterranean flow of contaminants draining from a zone of contaminant concentration, includes(a) determining the locus of flow of contaminants in a porous underground formation, and(b) injecting into the formation a substance that creates a barrier in the formation to said flow, to thereby block said flow.

Abstract: The invention provides a method for improving the nature of soil in a salty land not suitable for agriculture by forming a moisture barrier in the soil with formation of a water-impermeable layer of soil underground. The method comprises sprinkling a water-soluble polymer, e.g. a copolymer of acrylic acid, or polymer blend including, for example, polyacrylic acid, capable of being insolubilized by interacting with the salt, preferably, in an aqueous solution over the salty land so that a water-impermeable layer underground is formed by the insolubilized polymer together with the soil particles.

Abstract: Fluid leakage through soil in a region thereof is controlled by sequentially passing over the region to dig a plurality of parallel, laterally displaced grooves in the surface. Soil dug from each groove is temporarily stored, and a strip of sheet material is laid over a groove as it is created during each pass, the width of the strip being greater than the width of the groove. Thereafter, the temporarily stored soil is deposited on the strip such that it is covered with soil except along one edge, the other edge of the strip overlying the uncovered edge of an adjacent strip laid down during a previous pass over the region. As a consequence, a first layer of overlapping strips of sheet material covered with soil is installed over the region.

Abstract: A groundwater protection system is provided for a surface impoundment or landfill wherein contaminated material is contained in a first compartment. A second compartment is located beneath the first compartment and contains a plurality of treatment materials for acting upon leakage from the first compartment. Treated leakage is collected by a drain system and is recovered therefrom for subsequent treatment and/or disposal.

Abstract: Disclosed is a method for minimizing the entry of water into a mined cavity or underground formation which has thereabove a semi-permeable layer of a shaly material or rock directly below a source layer of water-saturated sand. By means of a borehole, a fluid such as air or oil is injected into a semi-permeable layer to displace water from it. The injected fluid acts as a barrier to reduce the downward leakage of water into the cavity.

Abstract: Method for constructing a screen that restricts or obstructs the flow of subsoil water in the ground by providing in the ground, from the land level downwardly, subsoil water retaining wall elements that engage each other and are in the shape of wide more or less supple films or sheets, that therefore with their lower edge are releasably connected to a flushing lance that in essense is as wide as each film and said lance after insertion of the film in the ground is released and retracted.The invention aims to provide a method with which it is possible to construct in a very simple manner a good seal and coupling of the films adjoining each other.

Abstract: A waterproof membrane comprising an elastomeric sheet, said sheet formed of a composition which includes a neutralized acid group containing elastomeric polymer, the neutralized acid group cation selected from the group consisting of ammonium, antimony, aluminum, iron, lead and a metal of Group IA, IIA, IB or IIB of the Periodic Table of Elements and mixtures thereof; a non-polar process oil; carbon black and a preferential plasticizer is disclosed. In a preferred embodiment the membrane is supported with a supporting sheet, said sheet selected from the group consisting of fabrics, paper and metal foil. The use of this membrane as a roof covering, pond, pit or aqueduct liner is recited. The method of forming the membrane, and the resultant roof covering, pond, pit or aqueduct liner is also disclosed.

Abstract: A process for forming a gel by gelling an aqueous solution of a water-soluble polymer with a chromium compound as a gelling agent, in which a copolymer of acrylamide, 0.5 to 40% by mole of an unsaturated sulfonic acid or its salt, and optionally an unsaturated carboxylic acid or its salt having an intrinsic viscosity of at least 10 in 1N-NaNO.sub.3 at 30.degree. C., is used as the water-soluble polymer, and which is availably applied to improvement of water-oil ratio in oil production and to civil engineering for preventing leakage of underground water. The formed gel is very stable in a water system containing salts in high concentrations at high temperatures.

Abstract: Aquatic plant growth can be reduced or eliminated in a pond or lake by placing a silicone rubber-coated fabric over the area where such plants want to be eliminated.

Abstract: A device for providing a moisture impervient barrier, comprises a flexible base sheet member having a layer of bentonite resting on its upper surface. A top sheet member is positioned over the bentonite and is secured to the base member by stitches extending therebetween. The stitches form either a quilting pattern or in the alternative, they can form elongated corrugated compartments filled with bentonite which will swell and break the top sheet member when exposed to water.

Abstract: The present invention provides a method and apparatus for constructing pipelines in Arctic offshore waters by a directional drilling technique, thereby minimizing exposure to ice gouging and eliminating the hazards associated with unstable permafrost. A special drilling-pipeline construction vessel is also provided which has a conical shape with reinforced outer walls to resist ice forces, which vessel includes means to install deep underground pipeline segments and means to connect and protect the pipe ends.

Abstract: The present invention relates to a non-hydrated bentonite intimately contacted with a polypropene, polybutene, or mixtures thereof to provide a formable and shapable non-aqueous bentonite composition particularly useful as a water barrier. The bentonite composition can be extruded in the form of a rope, rod, sheet or the like and is sufficiently tacky for adherence to a wall or conduit, floor or roof in areas of potential water flow to prevent the seepage of water through the bentonite composition. In one embodiment, the bentonite composition includes a polypropene and a polybutene and an elastomer, such as butyl rubber, having sufficient resilience to stretch or expand with the expanding bentonite upon hydration and to aid in maintaining the structural integrity and cohesiveness of the composition. In another embodiment, the composition comprises bentonite, an elastomer, and any plasticizer compatible with the elastomer.

Abstract: The present invention relates to a nonhydrated bentonite intimately contacted with a polypropene, polybutene, or mixtures thereof to provide a formable and shapable non-aqueous bentonite composition particularly useful as a water barrier. The bentonite composition can be extruded in the form of a rope, rod, sheet or the like and is sufficiently tacky for adherence to a wall or conduit, floor or roof in areas of potential water flow to prevent the seepage of water through the bentonite composition. In one embodiment, the bentonite composition includes a polypropene and a polybutene and an elastomer, such as butyl rubber, having sufficient resilience to stretch or expand with the expanding bentonite upon hydration and to aid in maintaining the structural integrity and cohesiveness of the composition. In another embodiment, the composition comprises bentonite, an elastomer, and any plasticizer compatible with the elastomer.

Abstract: A laminate suitable for use as a pond or pool liner is shown, the laminate comprising a batt of non-woven polyolefin fabric weighing 100 to 300 grams per square meter having thermally bonded thereto an ethylene/butylacrylate polymer in an amount of 600 to 1200 grams per square meter, said copolymer containing 10-25 weight percent butylacrylate.

Abstract: This invention relates to a method for introducing a ground water flow restricting or sealing screen into the soil comprising several side by side mounted whether or not overlapping flexible sheets which each are introduced into the soil with their lower edges by being releasably connected to a lance with substantially the same width and are sealed there to each other and anchored such that a continuous screen is formed, said lance being retracted after the placing of each individual sheet, the sealing of the edges being performed by overlapping and/or hardening material fed in at the location of said edge.

Abstract: A geotextile fabric, method of manufacture and method of use, are provided. The composite geotextile fabric has a first group of uncrimped synthetic weft threads, a second group of uncrimped synthetic warp threads not interlaced with the first group, and a knit yarn stitch bonding the warp and weft threads loosely together. A nonwoven filtration fabric may also be included. The composite geotextile fabric may have a controlled extensibility, which preferably is equal to or less than the two to four percent extensibility of asphalt paving, making the fabric suitable for use in repairing cracked road surfaces and the like.

Abstract: In a process of safely disposing of waste materials which are solid or contained in aqueous liquids, wherein the waste material is treated with alkaline substances and a solid product is formed, the waste materials which are solid or dissolved or suspended in aqueous liquids are mixed in accordance with the invention with brown coal ash and, if desired, with water, to obtain a homogeneous mixture having the consistency of a pulp or freely flowable slurry and the proportions of the mixture are so selected that it hardens to a material which is virtually impermeable to water. Such materials can be used to dispose of waste materials, such as waste acids, and to seal underground or surface dumps.

Abstract: A pond for the storage of hazardous materials, such as irradiated nuclear fuel elements, under water. Upper (8) and lower (6) impervious membranes extend without interruption beneath the floor (1) of the pond and the edges of the membranes lead into a trench (9) surrounding the pond. Any leakage through the floor is directed normally by the upper membrane (8) into the trench (9). The lower membrane (6) provides an additional impervious barrier in the event of a leak in the upper membrane (8) and again directs the leakage into the trench thereby avoiding contamination of the ground beneath the pond.

Abstract: A chemical waste landfill comprising a plurality of compartments separated by and lined with a primary clay liner. A single integral synthetic water impervious liner is provided beneath the clay liners of all of the compartments and a primary underdrain system is provided for each compartment beneath the synthetic liner. A secondary clay liner is provided beneath the primary underdrain system and a secondary underdrain system is provided beneath the secondary clay liner. The invention also includes chemical waste landfills having in situ leachate treatment systems, increased security compartments having additional synthetic and clay liners and a leachate monitoring system comprising a plurality of standpipes interconnected by a liquid pervious means below the waste wherein the standpipes are protected by sleeves.

Abstract: A containment reservoir for a liquid, such as petroleum oil, comprising, a walled ground containment space or pit, opening upwardly, with the space containing a liquid impervious flexible liner generally following the contour of the space, and with the liner comprising a layer of pervious fabric material having on at least one of its sides a layer of liquid impervious material, such as rubber, the liner being operable to prevent escape of liquid through the liner from the containment space; means are provided coacting with the liner covered containment space for removing liquid from the reservoir. A covering layer of pervious fabric material filters anything, including liquid, passing into the reservoir. A method of forming the reservoir from predetermined width strips of liner stock, and a method of retaining and salvaging oil spilled along a railroad track environment is also disclosed.

Abstract: A method of constructing a means suitable for directing, transporting or holding water is disclosed. Cloth is layed upon a surface convenient to a depression suitable to direct, transport, or hold water. The cloth is coated with a liquid silicone elastomeric composition curable at atmospheric conditions. The composition cures to an elastomer having a modulus which provides sufficient flexibility to the coated cloth so that the coated cloth will assume the contour of the depression, the coated cloth being impervious to liquid water. After curing, the coated cloth is moved to the depression and placed into the depression to cover the surface of the depression. The coated cloth is bonded at seams and the perimeter of the coated cloth is stabilized. The method yields a structure that is economical to manufacture, yet has a long, useful life in such applications as catchments, irrigation ditches, and holding ponds.

Abstract: The primary purpose of the present invention is to preseal a pit by adding a specially designed sealing material to the pit bottom prior to putting other materials, e.g., waste material, into the pit, e.g., a disposal pit.In accordance with the present invention a method for sealing the bottom of a pit is provided to minimize leakage from the pit comprising mixing a sealing material preferably an admixed soil liner in combination with bentonite clay or a bentonite/polymer (e.g., polyurethane-polymure) mixure mixed with native soil, in a fluid mixing tank, such as far as for preparing drilling mud for a well, connecting a pump and hose to the fluid mixing tank, dispensing a layer of the sealing material from the fluid mixing tank through the pump and hose and onto the bottom and sides of the pit, e.g., a disposal pit, and allowing the dispensed layer of sealing material to seal the bottom and sides of the pit. Preferably, the method includes removing materials, e.g.