Abstract: A manhole having a splayed rib ring extending from under a lid, an annular supporter having a beveled underside extending around the opening of a ring seat, and an insulation hood attached to an inner side of the splayed rib ring. Both the splayed rib ring and the annular supporter may or may not be concentric with the lid or the ring seat, respectively. Vibration and possible bouncing of the lid is reduced or offset because the splayed rib ring of the lid is retained by the bevelled underside of the annular supporter. A half round groove formed around an outer bottom periphery of the lid accommodates a rubber gasket which prevents the lid from directly contacting the annular supporter, and absorbs and relieves vibration of the lid to reduce the possible noise. The insulation hood completely prevents any worn cables under the manhole from directly contacting the lid and therefore, prevents any possible leakage via the lid that might endanger vehicles and walkers passing by the manhole.

Abstract: A pick hole plug for sealing an opening in a manhole cover and the process for using such plug. The plug is formed from a soft uncured rubber polymer which has a larger diameter than the hole which it is to seal. The plug is compressed by hand and inserted into the pick hole. The plug deforms to conform to the shape of the sides of the pick hole and cures over a period of time as the heat and sunlight contact it.

Abstract: A temporary reusable storm drainage conduit plug sized to slidably fit into the end opening of a length of tubular conduit situated within the ground. The device in use prevents dirt and debris from entering the open end of conduit already in place during storm drainage construction and is easily manually removable when the construction is ready to proceed further.

Abstract: An assembly intended for use on underground storage tanks provides ready access to a fill pipe from ground level. At the same time the assembly serves as a spill containment means for accidental spillage and a secondary containment means for the fill pipe. The assembly of the invention comprises a secondary containment chamber having a sidewall with means for attaching to the storage tank. An anchor ring which is attached to an upper open end of the containment chamber acts as a permanent ground base for the assembly. A bridging surface cover within the anchor ring has a removable lid positioned in its interior portion to gain access to the chamber's interior for a filling operation. The assembly also comprises a fill pipe for delivering liquid to the storage tank. The fill pipe is positioned within the secondary containment chamber with a discharging end extending through the chamber's bottom and a receiving end terminating within the chamber but near the bridging surface cover.

Abstract: A manhole rim and cover assembly includes a rim formed with an annular upwardly projecting lip extending around its central opening with a shoulder projecting radially inwardly from the lip at a location spaced below its upper edge. A cover has circumferentially spaced circumferential segments projecting downwardly from its lower surface to fit within the inner side of the lip and to rest upon the shoulder referred to above to prevent crushing of a sealing gasket received between the bottom of the cover and the upper edge of the lip. Vent openings are formed through the lip to vent the manhole when the cover is in place. Spring clips on the cover engage an undercut shoulder on the rim to releasably retain the cover against removal from the rim.

Abstract: An apparatus and method is provided for providing a mold that can be filled with sealing material to establish a barrier seal on top of a manhole to block unwanted inflow of groundwater into the manhole through a space or gap between either the manhole and manhole frame or a pair of adjacent manhole sections. The apparatus includes a pair of circular channel rings that can be mounted on the top face of the manhole. The channel rings are arranged to form an annular sealing material-retaining channel therebetween. The channel rings are strong enough to support a heavy manhole frame (or another manhole section) above the manhole and in contact with the sealing material in the annular channel. The sealing material cures to establish a water-tight pliable seal bonding the manhole frame (or other manhole section) to the manhole.

Abstract: Apparatus for monitoring gas pressure in a drain line including a housing, a liquid trap within the housing interior, a liquid collector for collecting liquid displaced from the trap when gas pressure in the drain line exceeds a predetermined level, and a valve for introducing air into the housing when a negative gas pressure exists in the drain line.

Abstract: An environmental monitoring well housing and protection method. A housing is disposed over the end of an environmental monitoring well pipe and set in concrete along with the well pipe itself so that the space between the housing and the well pipe is filled with concrete below the end of the well pipe. Fins extend outwardly from the housing into the concrete to anchor the housing. The housing has an interior ledge for receiving and supporting a cover. A flexible gasket is placed on the ledge, the cover is placed on the flexible gasket, and the two are fastened down by a pair of bolts that screw into threaded bores in the ledge. The bolts have five-sided heads and a special tool is provided for installing and removing them. The cover thickness is substantially the same as the distance from the top of the housing down to the ledge, so that where the top of the housing is mounted flush with the ground the top of the cover is also flush with the ground.

Abstract: A swing away manway assembly for a tubular fluid conveying system having a manway opening in a first horizontal plane, the assembly including a cover disposed in a second parallel horizontal plane. The manway cover includes a circumferential sealing means for continuous sealing of the manway opening. The cover is provided with latch means for alternatively engaging and releasing the sealing means. Swing away means is secured to the cover in a plane perpendicular to the first and second horizontal planes of the cover and opening. The swing away means is adapted to facilitate swinging movement of the cover in a horizontal plane upon release of the sealing means. The swing away means includes biasing means for cooperation with the latch means in urging sealing engagement of the cover with the opening, and cam means for limited vertical movement of the cover during horizontal rotation thereof.

Abstract: A fuel containment cover assembly comprising a fiberglass skirt with cast iron inserts molded into an integral unit. The inserts are located on the outer perimeter of the skirt and determine the flow of water from the cover to the ground. A pre-molded gasket extends about the interior perimeter of the cover. The gasket seats on the skirt assembly and seals the fuel containment device from the atmosphere. The cover is bolted to the fiberglass skirt and forms a drainage channel between the cover and the skirt.

Abstract: A covering for a ground opening includes a frame in which a cover can be inserted. The frame has a recess for receiving a retaining web shaped onto the edge of the cover. A niche with a sloping bearing surface is formed in the frame at a distance from the recess. The cover has a cam. When the cover is in the closed position, a supporting wall provided on the cam formed on the cover edge rests on a bearing surface of the frame, so that, on closing the cover, the later is moved in the direction of the recess and assumes a locked position. Thus, the cover is held in a clearance-free manner in the frame.

Abstract: A manhole cover comprises a top having a top surface and an edge portion, a depending portion having a sidewall and a bottom surface, and an interior chamber. The manhole cover is fabricated from a first material, while the interior chamber is at least partially filled with a second material. The manhole cover preferably includes recessed handles which are recessed into the top and extend downwardly through the bottom surface. Cooperative engagement means in the form of inter-fitting indentations and protuberances are provided in the top surface and the bottom surface respectively. The bottom surface includes a first surface portion which includes a peripheral edge portion and a bracing portion. The bracing portion includes a plurality of brace members each of which have a lower brace surface and a brace sidewall.

Abstract: A containment device for minimizing soil contamination in filling underground storage tanks, comprises a bucket member, a bottom member and a bellows connection between the bottom member and a riser pipe extension. These elements comprise an upwardly open spillage container. A lower bellows connects the bottom member and the riser pipe extension, comprising a lower chamber. The containment device is mounted on the riser pipe of an underground tank by threading the lower end of the riser pipe extension thereon. A valve controlled passage, through the bottom member, permits spilled fuel to be drained from the spillage container into the lower chamber and then through openings in the riser pipe extension into the storage tank. The bottom member is releasably secured to the bucket member and the bellows are releasably clamped to the riser pipe extension, to permit these items to be removed from the bucket member for repair and replacement.

Abstract: Apparatus is provided for use in cooperation with a liquid-receiving pipe for catching and temporarily storing spilled or overflowed liquid as the liquid is being transferred into the pipe. An elastic band grips the pipe in liquid-tight relationship, and the band supports the apparatus on the pipe. A flexible sleeve is connected in liquid-tight relationship with the elastic band for fitting over and around the pipe to form an inner liquid-retaining wall. A funnel is connected in liquid-tight relationship with the sleeve for positioning over and around the pipe and over and around the sleeve to form an outer liquid-retaining wall. The funnel cooperates with the sleeve to create a container for catching and temporarily storing the spilled or overflowed liquid.

Abstract: An access cover for a manhole of the kind in which the removable cover member fits within an outer surrounding frame (2), the cover being in the form of an inner frame (5) containing an appropriate filling material (11), such as concrete. The appearance of the upper edges of the inner and outer frames is enhanced by providing the upper edges with decorative strips (12) which are positively fixed to the upper edges of the frame members (2, 6) by a tongue and groove joint (21, 22). Preferably, the groove (21) is formed with at least one splayed-out wall (20) which, after assembly, is pressed into longitudinal engagement with a corresponding wall of the tongue (22). An insulating layer (23) can be provided to prevent any chemical reaction between the frames and strips when they are of dissimilar metals.

Abstract: A gasket secured to the cover frame of an underground vault. The vault is of the type having a precast underground portion and an upper opening including a steel cover frame with a horizontal, flat surface to which the gasket is adhered. The gasket has a plurality of ridges along its inner edge, a flat center portion wherein the bolt holes are located and an outer ridge adjacent the bolt holes but separated from the outer edge.

Abstract: A sump cover containment assembly is provided for use with containment sumps utilized with underground fluid holding tanks having a sump cover with an access hole therein, a frame which communicates with the containment sump to which the sump cover is attached and a sump shield positioned between the containment sump and the frame and having a hole which communicates with the interior of the containment sump as well as with the sump cover access hole.

Abstract: A locking manhole cover and key combination of the present invention is in the form of a manhole cover having a lock on its undersurface and a vent hole through the manhole cover. The lock comprises a plurality of locking bars spring biased to a locking position, a rotatable actuator accessible through the vent hole for moving the locking bars to an unlocking position with the key being fittable through the vent hole to operate the actuator. The key itself includes a first shaft portion turnable in the vent hole for rotating the acutator and pulling the locking bars to the unlocking position and a second shaft portion which when located in the vent hole prevents rotation of the actuator and holds the spring biased locking bars away from the locking position.

Abstract: The raising structure according to the invention is intended to raise a manhole cover to the level of the resurfacing new layer of asphalt. The raising structure comprises a pair of superposed concentric rings one of which is slightly smaller than the other one so that the outer diameter of the smaller one is slightly smaller than the inner diameter of the other one. The rings are maintained in a spaced relationship by a set of spacer legs disposed around the periphery of the inner ring. Each of the legs have one end secured to the outer periphery of the small ring and the outer end of the leg is secured to the inner periphery of the larger ring. The legs are characterized by at least one bent section between both ends of the legs. The bent section extends in a plane tangent to the outer periphery of the smaller ring and the inner periphery of the larger ring. The bent section is adapted to define a weak section in the legs for allowing a change in the angle of the bent upon pressure on one of the rings.

Abstract: In a cover-frame assembly for a manhole or the like a locking device is provided, which comprises a closing member having at least two horizontal arms and a mounting rod provided with a bearing and actuating device. The mounting rod and the bearing and actuating device are located in a bore having a widened bore portion, whereby a shoulder is formed, on which is supported a bearing surface of the bearing and actuating device. The ends of the arms each project into a guide link, which is shaped on the inner flange of the frame. The guide link has an inclined flank, by means of which the arms are increasingly elastically deformed. In the closed position of the locking device, the arms engage in locking recesses provided on the end of each inclined flank. This leads to a self-closure with pre-tension.

Abstract: An environmental monitoring well housing and protection method. A housing is disposed over the end of an environmental monitoring well pipe and set in concrete along with the well pipe itself so that the space between the housing and the well pipe is filled with concrete below the end of the well pipe. Fins extend outwardly from the housing into the concrete to anchor the housing. The housing has an interior ledge for receiving and supporting a cover. A flexible gasket is placed on the ledge, the cover is placed on the flexible gasket, and the two are fastened down by a pair of bolts that screw into threaded bores in the ledge. The bolts have five-sided heads and a special tool is provided for installing and removing them. The cover thickness is substantially the same as the distance from the top of the housing down to the ledge, so that where the top of the housing is mounted flush with the ground the top of the cover is also flush with the ground.

Abstract: A self sealing sewer cover assembly including a dome shaped removable cover for preventing flammable and/or toxic gases from being discharged from a sewer, and for preventing the ignition of gases in a sewer by flames and sparks in the area adjacent to the sewer inlet. The cover assembly may be inserted into the inlet to a sewer. the apparatus of the present invention provides a water barrier between gases contained in the sewer and the ambient air adjacent to the sewer inlet which prevents the flow of gases from the sewer to the ambient air surrounding the sewer inlet.

Abstract: An assembly intended for use on underground storage tanks provides ready access to a fill pipe from ground level. At the same time the assembly serves as a spill containment means for accidental spillage and a secondary containment means for the fill pipe. The assembly of the invention comprises a secondary containment chamber having a sidewall with means for attaching to the storage tank. An anchor ring which is attached to an upper open end of the containment chamber acts as a permanent ground base for the assembly. A bridging surface cover within the anchor ring has a removable lid positioned in its interior portion to gain access to the chamber's interior for a filling operation. The assembly also comprises a fill pipe for delivering liquid to the storage tank. The fill pipe is positioned within the secondary containment chamber with a discharging end extending through the chamber's bottom and a receiving end terminating within the chamber but near the bridging surface cover.

Abstract: A locking device for a covering comprised of a frame and a cover includes arms, which are inserted in depressions or bores formed in the frame and/or cover, whereby they undergo elastic deformation and consequently form a frictional engagement with the cover. The free end each of the arms project beyond an inner flange of the frame and form there a positive connection between the arms and the inner flange. This results in a simple, but effective connection between the cover and the frame, without requiring machining of the arms or depressions.

Abstract: To provide a temporary cover for a maintenance hole (1, 31), over an edge (5) of which cables, hoses or other conduits (3, 83) extend, an inflatable balloon (10, 40, 50, 60, 70, 80) has hollow circumferential portions (41, 51, 61, 71, 81), for example generally in the shape of a tire or hollow disk, connected by a web (12), the balloon having a plan view configuration and dimension to fit into and, upon inflation, over the edge of the maintenance hole, and resiliently engaging around the edge of the maintenance hole, thereby preventing ingress of water, contaminants, animals and the like, without damage to the cables, hoses or conduits. Preferably, the balloon is a unitary structure made of distendable material such as rubber, plastic or the like, which may be fiber or textile reinforced.

Abstract: An improved extension shield for a manhole is disclosed. The shield seals around an open manhole frame protecting the instruments and men working inside from rain, snow, surface water and other elements. The shield is adapted to be installed in four differently sized openings and is constructed to preferably seal inside the lip of the manhole frame rather than on top of the lip. The shield is made of a durable molded plastic material and is stackable to create higher shields or for storage.

Abstract: A sealing system is provided for a prefabricated pit for servicing an aircraft that is formed with an open bottom and an inner cylindrical wall for surrounding a riser pipe therewithin. An annular rubber boot having annular inner and outer marginal edges is located at the bottom of the pit. The inner peripheral margin of the boot is secured to the riser pipe by a conventional metal band clamp to establish a liquid tight seal therewith, and the outer peripheral margin of the boot is compressed radially outwardly against the cylindrical wall surface by means of an outer clamp.

Abstract: A vertically adjustable manhole cover assembly providing for ease of vertical adjustment and stable support of the manhole cover subsequent to roadway resurfacing. The manhole cover assembly utilizes annular adjustment rings at both the bottom and top of a vertically adjusted annular sleeve positioned within the annular frame of the manhole cover assembly for support of the manhole cover. The upper annular support ring includes an annular flange extending radially outwardly beyond the annular frame which is captured by the roadway resurfacing material so as to provide additional support to the vertically adjustable manhole cover assembly after road resurfacing.

Abstract: A peripherally adjustable insert is shown for raising the grade of a generally rectangular grating that previously was supported by the end sills of the frame and by the roadway-side longitudinal sill if the frame has one. The insert comprises a base having support elements, the base being adjustable in length and adapted to rest on said sills, and ledge and keeper elements supported by the base to seat the grating restrict its lateral movement. The support elements of the base comprise a pair of essentially parallel end elements and a pair of essentially parallel side elements, and the support elements being equipped with terminals that are joined to form these base elements generally into a rectangle.

Abstract: The present invention relates to a pad which supports a utility access conduit in a roadway and permits relative movement between the conduit and the roadway without damaging the seal between them and which supports vehicular traffic for a time comparable to the life of the roadway itself, without the occurrence of any dipping in the vicinity of the access conduit. This is accomplished with a rectangular block or rubber or similar compressibly resilient elastomeric material which has an opening passing through it that snugly engages the access conduit. The invention also relates to a method for installing the pad in either a new or existing roadway.

Abstract: A sewer catch basin assembly for preventing gases from being discharged from a sewer of a petroleum refinery or chemical processing plant and for preventing the ignition of gases in a sewer by flames and sparks in the area adjacent to the sewer inlet. The catch basin assembly may be connected to a vertical pipe or "Tee" inserted in an existing or new horizontal sewer pipe, and can be used to replace an existing sewer inlet or catch basin. The catch basin assembly provides a water barrier between gases contained in the sewer and the ambient air adjacent to the sewer inlet which prevents the flow of gases from the sewer to the ambient air surrounding the sewer inlet.

Abstract: A trench grate includes angular frame members having a number of spaced apart rectangular openings along a downwardly extending leg to receive L-shaped tabbed ends of cross members located transversely between the two angular frame members. The portion of the L-shaped tabbed member extending through the opening in the downwardly projecting leg is welded to an outer face of the downwardly extending leg to form an ingegral unit. The trench grate is a single piece unit and rests on the lip surface of a subterranean drainage structure.

Abstract: A covering for a ground opening includes a frame in which a cover can be inserted. The frame has a recess for receiving a retaining web shaped onto the edge of the cover. A niche with a sloping bearing surface is formed in the frame at a distance from the recess. The cover has a cam. When the cover is in the closed position, a supporting wall provided on the cam formed on the cover edge rests on a bearing surface of the frame, so that, on closing the cover, the later is moved in the direction of the recess and assumes a locked position. Thus, the cover is held in a clearance-free manner in the frame.

Abstract: A safety device for sealing a drain assembly including a plate element defining a basin with the drain assembly, a housing element depending from the plate element closed to an underground line associated with the drain assembly, and a seal element positionable between the plate element and drain assembly to provide a substantially fluid-tight seal therebetween when liquid fills the housing element interior.

Abstract: An environmental monitoring well housing and protection method. A housing is disposed over the end of an environmental monitoring well pipe and set in concrete along with the well pipe itself so that the space between the housing and the well pipe is filled with concrete below the end of the well pipe. The housing has an interior ledge for receiving and supporting a cover. A flexible gasket is placed on the ledge, the cover is placed on the flexible gasket, and the two are fastened down by a pair of bolts that screw into threaded bores in the ledge. The cover thickness is substantially the same as the distance from the top of the housing down to the ledge, so that where the top of the housing is mounted flush with the ground the top of the cover is also flush with the ground. The cover includes recesses for the heads of each of the bolts, so that the resultant well head is entirely flush with the surface of the ground. The flexible gasket has an adhesive material on its underside for attachment to the ledge.

Abstract: In a street manhole defining an elongated manhole duct provided with a rigid collar at its top mouth, the collar having a radially inward annular cavity defining a base wall, parallel to the plane of the collar and a side wall, orthogonal to the base wall. The collar further defines a top wall parallel to the base wall. A spacer device is provided for raising the cover level from the collar base wall, and defines: (a) a first rigid ring, destined to sit on the collar base wall; (b) a second rigid ring, diametrally larger than the first ring and destined to sit on the collar top wall; and (c) connecting tongues, for coaxially interconnecting the rings about spaced planes, the connecting tongues being flexible and capable of bending under load, so as to bring the first ring to sit against the collar base wall and the second ring to sit against the collar top wall.

Abstract: This invention relates to a spacer for a manhole cover for use in a manhole frame comprising a ring having a mounting surface adapted to sit on the top of a manhole cover frame. The ring has a seating surface for, in use, the seating of a manhole cover thereon. The seating surface is spaced radially inwardly of the mounting surface. The ring has a downwardly extending portion below the seating surface. The downwardly extending portion has a lesser outside diameter than the portion above said seating surface to enter into the manhole cover frame in use.

Abstract: A closure for excavations is provided, which comprises a plate which rests on and is supported by the edges of an excavation site. The upper surface of the plate is substantially flush with the surrounding street surface, and the plate has at least one lift opening. A bale handle is provided, wherein the bale handle is pivotally connected to the plate adjacent to the lift opening so that the bale handle can pivot 360.degree. through the lift opening.

Abstract: A manhole cover including a frame and a lid having an insert plate on its upper surface. The lid is insertable into the frame which is provided in the road surface. Securing screws are provided for detachably securing the insert plate to the base portion of the lid from the underside of the lid. The insert plate is configured as an advertising area.

Abstract: An apparatus for covering the top of a monitoring well with a lockable, weathertight cover which can be easily removed to allow ready access to the monitoring well so that water samples can be taken as desired. The device is positioned over the monitoring well casing in such a manner that when installation is complete, the monitoring well cover is mounted flush and level with the surrounding terrain.

Abstract: An improved cover lock apparatus comprises a rotatable and axially slidable crank plate connected to a plurality of retractable lock rods. The crank plate is disposed between the cover and a lock plate and is slidably and rotatably mounted to the lock plate. The crank plate has two upwardly protruding lock pins oriented to engage mating holes in the lock plate and is upwardly biased against the lock plate by a spring. When the lock pins are engaged in these holes, the crank plate cannot be rotated to retract the lock rods. Before the crank plate can be rotated to retract the lock rods, the lock pins must be disengaged from the mating holes in the lock plate by forcibly pushing down on the crank plate via a special lock key to overcome the spring bias that normally holds the crank plate pins in the engaged position. Once the crank plate is pushed downward enough to disengage the lock pins, it can be rotated to retract the lock rods.

Abstract: A method and apparatus for sealing manholes which includes the installation of a donut-shaped seal structure in the chimney, cone or base of a manhole at a selected distance from the manhole cover and seating a dish-shaped manhole insert in an opening provided in the seal structure to define a manhole seal. The seal structure element of the manhole seal is installed by initially mounting a flexible form base to the chimney, the concentric or eccentric cone or the base of a manhole by means of anchor bolts and masonry anchor plugs. A flexible form is then seated on the form base and concrete is poured in the annulus between the form base and the chimney wall, in order to define the seal structure. A manhole insert seal may then be seated in the top surface of the seal structure for receiving the flange or rim of the manhole insert component of the manhole seal.

Abstract: A frame for a manhole comprises a cylindrical pipe portion and an outwardly projecting lateral flange portion located on the outside of the pipe portion. Projections are provided on the inside of the portion and on these can be supported a cover or grating. The flange portion is constructed as a cohesive collar, which projects substantially horizontally outwards. The flange portion is located at a height below the upper border of the pipe portion. This height is a third to a half of the total height of the pipe portion. Due to the fact that the flange portion is spaced from the upper end of the pipe portion, during the installation of the frame, it is surrounded at all sides by the material of the ground surface, so that the frame is connected in stable manner to the ground material and cannot be significantly displaced by the traffic flow.

Abstract: An improved gasket for use with manhole covers. The gasket is of the type which is fabricated from rubber and is held in a circular groove formed in the flat cover support surface of a cast iron frame of the type which holes a manhole cover. The manhole cover fits in the frame and rests on the gasket. The improved gasket has a vertical portion which is generally rectangular which fits into the circular groove. The gasket also has a horizontal portion which extends beyond the groove and onto the flat cover support surface of the frame.

Abstract: An infiltration system for a manhole and manhole cover assembly, the system including an infiltration disk positioned between the manhole and cover assembly, the disk including a flange encircling the manhole and cover assembly and a filtration means in the gap between the flange and cover assembly to prevent ingress of solid matter into the space between the manhole cover and the disk.

Abstract: The present invention relates to a pad which supports a utility access conduit in a roadway and permits relative movement between the conduit and the roadway without damaging the seal between them and which supports vehicular traffic for a time comparable to the life of the roadway itself, without the occurrence of any dipping in the vicinity of the access conduit. This is accomplished with a rectangular block of rubber or similar compressibly resilient elastomeric material which has an opening passing through it that snugly engages the access conduit. The invention also relates to a method for installing the pad in either a new or existing roadway.

Abstract: The manhole covering comprises a casing, a base frame and an adjusting device. A two-part base frame has a plurality of bores, which are aligned with pockets located in the base part of the casing. In each pocket is inserted a screw nut, into which is screwed and secured the lower end of a threaded bolt extended through the assigned bore of the base frame. The base frame is adjusted in height and slope by a pair of nuts. The adjustment of a particular slope is made possible due to the shape of the bores, which widen to either end and by convexly curved washers cooperating with the bores at their ends. The screw connection of the base frame constitutes a positive connection, which prevents breaking out of the base frame even in the case of a high, eccentric force application to the manhole covering.

Abstract: A watertight manhole insert which is characterized by a dish-shaped seal or stopper designed to prevent rainwater from entering a sanitary sewer system through a manhole closed by a manhole cover. The manhole insert is located beneath the manhole cover and serves to plug the manhole and prevent flooding of the underlying sewer system. The manhole insert is characterized by a dish-shaped bowl having a pressure-relief valve, an optional vacuum relief valve and left strap and a substantially perpendicular, upward-standing side wall fitted with an outwardly-extending top rim for engaging a shoulder shaped in a manhole to support the manhole insert. Multiple, upward-standing bottom ribs radiate from the side wall inwardly in the curved bowl bottom toward the pressure relief valve, which is normally located in the center of the manhole insert, in order to stiffen the bowl-shaped bottom. Optional side ribs may also be provided in the vertical side wall for stiffening purposes.

Abstract: An adjustable manhole top which can be readily raised up or down in minutes to correct problems when the ground around it heaves. A cylindrical sleeve with a plurality of spaced elongated shoulders extending longitudinally along an internal surface thereof, is adjustably seated about upwardly extending projections from a support rim. A lock, removably supported on the support rim, is provided with a height adjustment mechanism to support a corresponding shoulder on the sleeve, to secure the sleeve at a desired height.

Abstract: A frame for forming coverings for ground openings and method of assembling such frame are disclosed. Frame parts for assembling the frame are provided at their ends with connecting lugs, which are arranged at different levels. On fitting the frame, the two frame parts are juxtaposed, their connecting lugs are arranged in spaced superimposed manner and are interconnected by screw couplings. For positively interconnecting the frame parts, the frame is turned upside down, and a liquid, pasty or granular filling material is filled into a bore on the underside of the upper connecting lug. The filling material also flows into the bore of the screw coupling, which is covered by a washer. Following the solidification of the filling material, the frame can either be transported in this state or in a disassembled state and can be then reassembled in the same way.