Hydraulic and earth engineering – Fluid control – treatment – or containment – Flow control
Reexamination Certificate
1999-07-19
2001-03-06
Neuder, William (Department: 3673)
Hydraulic and earth engineering
Fluid control, treatment, or containment
Flow control
C405S087000, C405S107000, C405S118000, C405S119000, C210S154000
Reexamination Certificate
active
06196762
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to systems for the conveyance of storm water runoff or water of other origin which sometimes carries debris and sediment, and more particularly, to a facility for removing such debris and sediment from open channels in such a system.
Systems for conveying untreated water such as storm water runoff typically incorporate both open channels and enclosed conduits. The open channels are either waterways in essentially their natural condition, or waterways which have been improved by enlargement, straightening, paving, or other means to increase their hydraulic capacity and reduce erosion of their banks. The enclosed conduits include both short lengths of enclosed conduit (culverts) under embankments, and extended lengths of buried piping or other buried conduit (storm sewers, drains, and transmission mains).
Runoff from unpaved land that enters a water conveyance system typically carries amounts of debris (such as tree limbs and discarded manufactured objects) and sediment (soil particles and rocks). Quantities of debris and sediment transported by the water increase with the water flow rate, and high rates of flow can carry quantities of these materials that may substantially interfere with operation of the conveyance system. Debris tends to be trapped and accumulate wherever there is an obstruction in the flow path, or a reduction in the size of the flow path. Sediment tends to deposit wherever the velocity of flow is reduced, either by enlargement of the channel cross-section or by eddy effects. In either instance, the hydraulic capacity of the conveyance system is reduced where the debris or sediment accumulates, causing the water level upstream of that location to be higher at all rates of flow. This almost always leads to more frequent flood damage to property and will often cause increased hazard to human life.
Bridge crossings of stream channels, and culverts under embankments that cross stream channels, are hydraulic “choke points” that are especially susceptible to blockage by debris, and present an especially high risk to people's lives and property. Obstruction of a bridge opening or culvert by debris or sediment reduces its hydraulic capacity. During periods of high flow, this causes upstream water levels to rise to the level of the bridge or the top of an embankment, and the water to flow over the roadway. The force of the current can wash vehicles off of the roadway into the stream, and can wash out the bridge or embankment.
The debris and sediment that accumulates in storm sewers also reduces their hydraulic capacity. This causes low-lying areas in a watershed to flood during more frequent, less intense rainstorms. Removing debris and sediment from an enclosed conduit is generally much more difficult and costly than removing these materials from an open channel, because of the difficulty of access to an enclosed conduit.
BRIEF SUMMARY OF THE INVENTION
A primary object of the present invention is a facility in a water conveyance system to remove debris and sediment from the flow of water in an open channel of the system while directing the flow into an enclosed conduit or a constriction in the open channel. By preventing debris and sediment from being carried into downstream components of the system, the facility prevents obstruction of the downstream components that would otherwise increase the incidence of flooding. The facility thereby reduces the hazard to property and human life that is associated with flooding.
Another object of the facility is to detain relatively large quantities of debris and sediment while causing only a minor rise in the upstream water level. This is achieved by enlarging the cross section of the channel configuration to reduce the water flow velocity, while directing the flow into a barrier extending across part of the channel.
An upstream, or “approach” section of the facility consists of a length of open channel that gradually widens and transitions from the shape of the open channel upstream of the facility, to a cross section having an essentially flat bottom and essentially vertical walls. As the cross section widens, the velocity of flow during high flow events is reduced, causing readily-settleable sediment carried by the water, such as sand and rocks, to be deposited on the floor of the facility.
The walls of the approach section are configured to direct flow towards an elongated barrier that extends across most of the “center” section, perpendicular to the direction of the flow. The base of the barrier is a low wall or curb typically made of concrete. At times of low flow, the flow will be diverted around the barrier through a bypass channel, and continues through an “outlet” section of the facility to the downstream conveyance system. When the flow rate increases to a value determined by the height of the base of the barrier and other dimensions of the particular installation, the water level will rise and a portion of the flow will pass over the base of the barrier.
A vertical screen mounted on top the barrier screens large debris out of the flow. The screen may be posts set at regular intervals, or some type of mesh might also be utilized to screen out smaller debris. Mesh, however, clogs more rapidly and is more difficult to clean.
As the flow rate further increases, the momentum of the large rate of flow passing through the barrier will hydraulically block (and even reverse) flow in the bypass channel, causing the entire flow to pass through the screen along the top of the barrier. In addition to supporting the screen, the barrier base serves to block any further downstream movement of sediment that settles onto the floor of the facility upstream of the barrier.
If a substantial quantity of debris accumulates on the screen of the barrier, a moderate rise in the level of the water at the upstream face of the barrier will occur and will cause a portion of the flow to divert into the bypass channel. This bypass flow may carry some debris that would otherwise be screened out by the barrier. However, it is an object of the invention that the barrier will still be effective at trapping very large items of debris such as tree trunks because their momentum will carry them into the barrier.
A further object of the invention is to provide a facility that can be constructed using standard techniques which are therefore economical. The facility is adaptable to any channel configuration, whether straight or curved, and can be installed in either new or existing conveyance systems.
Another object of the invention is a facility requiring relatively infrequent maintenance by unskilled personnel. The facility contains no moving parts. Larger installations of the facility can incorporate a ramp to provide access for personnel and maintenance equipment, during periods of low flow, to areas of the facility where debris and sediment accumulate. A front-end loader, for example, would generally be used to remove debris and sediment from the larger installations.
Another object of the invention is to reduce the risk of drowning in a water conveyance system by providing a region of reduced flow velocity where a person trapped in the flow is more readily able to escape. Achievement of this object is enhanced by permanently mounting one or more ladders on the sidewalls of the facility.
In accordance with the invention, generally stated, a non-clogging facility in a water conveyancing system collects debris and sediment carried by water flowing in an open channel upstream of an inlet to a conduit. A first section of the facility provides a transition from the open channel into a second section which allows for collection of large debris and readily settleable sediment. A barrier formed in the section comprises a base extending from a sidewall on one side of the channel, substantially across the width of the channel, toward the opposite sidewall. An opening is pro
Neuder William
Pechhold Alexandra K.
Polster Lieder Woodruff & Lucchesi L.C.
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