Liquid purification or separation – Processes – Including geographic feature
Reexamination Certificate
2000-08-15
2002-07-09
Hoey, Betsey Morrison (Department: 1724)
Liquid purification or separation
Processes
Including geographic feature
C210S767000, C210S163000, C210S166000, C210S170050, C210S232000, C210S460000, C210S462000
Reexamination Certificate
active
06416674
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to devices for controlling erosion at construction sites, and in particular to an apparatus that fits over and encloses and is removably mountable to the open end of an underground drainage pipe so as to trap and prevent solid particles and oily residues from being washed into or being otherwise deposited within the pipe, while still enabling water to drain therethrough.
BACKGROUND OF THE INVENTION
In the construction of new housing and other types of developments, it is often necessary, if not in fact required by local or state law, to provide drainage and/or detention ponds to deal with construction site debris, erosion of soil, and storm water drainage. In general, clearing, grading and leveling of the land results in erosion of the remaining bare soil. It is not permissible for the construction site manager to allow the construction site debris, silt, sand, rocks, and the like, to adversely impact the surrounding properties, by for instance, polluting the rivers and streams by silt carried from the land with rainwater or by clogging of the sewer lines.
Typically, the road system is first marked out and the streets into and through the development are cut and graded. Thereafter, the storm water drainage system for the development is constructed, which typically includes the underground drainage pipes, collection boxes and culverts, and drop inlets that form the manholes or drain openings along the street. Additionally, a detention pond, (otherwise known as retention or silt collection ponds), may be created, usually at the lowest elevation of the construction site, to collect the storm water runoff and the silt carried with it. An elongated cylindrical standpipe is commonly placed in a vertical orientation within the low point of the pond and a steel and gravel trash rack (see, for instance,
FIG. 1A
) or a V-shaped weir (see, for instance,
FIG. 1B
) is formed around the top of the pipe. A drainage pipe in communication with the standpipe at its bottom portion extends outside the pond. In use, rainwater flows from higher elevations of the land and fills the pond until the water level in the pond rises to the bottom of the V-shaped weirs. Excess water then drains through the weirs into the standpipe and out of the pond through the drainage pipe. The V-shaped weir and the trash rack are typically designed to create residence time in the pond to allow the silt to settle out of the water before the water enters the drainage system, rather than actively filter the solid particles from the water. Additionally, during periods of heavy water flow, there is no means to control the rate of flow through the drainage pipes, which may result in flooding of the drainage system.
Another problem associated with construction sites is the dispersion of oily residues on the soil. Such oily residues typically come from trucks, paving machines, heavy machinery and the like, by spills and/or leaks. During a rainstorm, the water will tend to entrap the oily residue, washing it away with the silt, which ends up polluting the storm water drainage system of the site.
Typically, in the construction of a storm water drainage system, culverts are installed after the street bed has been graded, whereupon drop inlets are then installed and connected to the culverts and to the collection boxes. The drop inlets generally are substantially cylindrical concrete pipes that are installed vertically, with their lower ends connecting to the collection boxes and drainage pipes, and their upper ends being substantially at street level. Once the grading of the street bed has been completed and the drainage system substantially installed, the drainage system then will be buried and the curbs for the street are graded and poured. Thereafter, throats are provided for the manholes, the throats being poured about the open ends of the drop inlets to form the curb inlets or drains and manholes along the sides of the streets through which storm water drains.
During the construction of roads and drainage systems, until the street has been substantially completed and the curbs and throats of the sewer system have been poured, the drainage pipes and inlets must be kept substantially free of dirt and debris pursuant to state and county building codes. Keeping dirt and debris out of the drainage system is, however, very difficult to accomplish. For instance, during grading of the curbs as well as additional grading on site, dirt and debris is pushed around the site by the motor grader or bulldozer, and thus may pass into the open upper ends of the drop inlets and/or detention pond drainage pipes. In addition, rain, runoff and wind also tend to wash or blow dirt and debris into the detention pond drainage pipes and open ends of the drop inlets, which then collects in the collection boxes and sewer drainage system.
If dirt and debris are washed into or otherwise collected within the collection boxes and/or other parts of the drainage system, it becomes necessary to unclog the system to comply with building code regulations. One such method of cleaning the system is to send laborers down into the drop inlets and collection boxes to manually clean out the dirt and/or debris that has been washed or accidentally dropped into the drainage pipes. Such cleaning operations are difficult as the pipes are somewhat cramped, making it difficult to maneuver, and there is also the danger of cave-ins or collapse of the dirt, etc. that has built up around the sides of the drop inlets, creating a significant risk of injury or even death to the laborers below. In addition, there can be as much as a ten to twelve-foot drop from the surface of the road, and the upper end of the drop inlet, to the bottom of the collection box on which the drop inlet is mounted. A fall from such a height can cause severe injuries to persons who might inadvertently fall into the inlet, especially as the open end of the inlet becomes obscured by dirt and other debris. The danger of an exposed, i.e. open, ten to twelve-foot drop inlet is especially great for children who might play around the area and are more likely to be curious and to inadvertently fall in and become trapped within the drainage pipes.
In the past, the open upper ends of the drop inlets generally have been protected with a simple silt fence constructed of a flexible mesh or screen material attached to a series of wooden stakes positioned about the open upper end of the drop inlet. Such an arrangement is illustrated in
FIG. 2A
, which shows in general the known method of enclosing and marking the open end of a drop inlet at construction sites. Such arrangements, however, have not proven satisfactory for preventing dirt and debris from falling into the open end of the drop inlet, and they provide little or no protection against persons inadvertently falling into an open drop inlet, and especially for keeping children out of the inlet.
In fact, as shown in
FIG. 2B
, the known silt fences typically tend to collapse, be blown down, or washed down over a short period of time. This is due to the fact that the mesh of the silt fence and the stakes holding the silt fence in place are not strong enough to withstand heavy rains and wind, and even less so the force of dirt and debris being pushed against the silt fence by a motor grader or bulldozer as the streets and curbs of the site are graded. Under such weight, as illustrated in
FIG. 2B
, the silt fence generally will collapse, often falling into the open enci of the drop inlet itself thus permitting the accumulated dirt and debris being urged or pushed thereagainst to fall into the drop inlet.
Although the simplest solution to this problem would seem to be to completely seal the open end of the drop inlet, this is not feasible in that rain and storm runoff water must be permitted to drain through the storm water drainage system of the development during construction to permit the ground to dry, and to prevent storm water from eroding the work site and carrying soil and debris to adjacent lo
Dobbs Raymond Joseph
Singleton Earl Roger
Hoey Betsey Morrison
Womble Carlyle Sandridge & Rice LLP
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