CA2264440A1

CA2264440A1 - Rainfall collection system

Info

Publication number: CA2264440A1
Application number: CA002264440A
Authority: CA
Inventors: Max E. Morrison; Jay Polon
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-02
Filing date: 1999-03-02
Publication date: 2000-09-02
Also published as: AU2899100A; WO2000052269A1

Abstract

A rainfall collection system extending over a wide area funnels collected rainwater into a central storage tube. A platform consisting of a plurality of water-impermeable membrane panels laid over a graded bed overlays a flexible watertight collection tube disposed within a swale running along the apex of the bed beneath the membrane panels.
Rainwater is automatically pumped into the collection tube as it accumulates on the membrane panels, preventing losses due to evaporation and percolation into the ground. The collected rainwater is stored in the storage tube and transported by an aqueduct system or tank trucks. The membrane panels may be transparent or translucent, allowing maintenance personnel to detect leaks in the panels by darkened areas of the ground visible via aerial inspection, and may be marked with coordinate identifiers allowing maintenance personnel to readily locate damaged areas from the ground. A grid of maintenance corridors interspersed throughout the collection platform allows access to the membrane panels for maintenance and repair. Sediment catchment pits may be located near each end of the tube to collect sediment.

Description

RAINFALL COLLECTION SYSTEM
Field of Invention This invention relates to water collection and storage systems. In particular, this invention relates to a rainfall collection system for collecting and storing rainwater as a source of potable water.
Background of the Invention Many arid regions of the world suffer from a scarcity of potable water.
Different methods axe conventionally used to produce potable water, the most popular being desalination of sea water. However, desalination is a slow and expensive process and the cost of purchasing, installing and maintaining a desalination plant renders it impractical in most densely populated regions, particularly inland regions.
Rainwater has heretofore been largely unavailable as a source of potable water in many regions where it rains only intermittently, because it is difficult to collect and store.
During heavy rainfall periods most of the rainwater is lost to the ground, and reservoirs tend to lose rainwater in a short time due to evaporation and percolation.
It would accordingly be advantageous to provide a rainwater collection system which collects large amounts of rainfall and is capable of storing collected rainwater for extended periods as potable water.
The present invention provides a rainfall collection system which extends over a wide area to maximize the collection of rainfall, and funnels collected rainwater into a central storage tube for prolonged storage without evaporation or percolation into the ground.

The system of the invention automatically transfers collected water into the storage tube, and requires minimal maintenance. The cost of collecting and storing rainwater in the system of the invention is substantially lower than the cost of desalination, both in terms of the cost of purchasing and installing the required facilities and in terms of maintaining ongoing potable water production.
The invention accomplishes this by providing a platform consisting of a plurality of water-impermeable membrane panels laid over a bed graded with a shallow "V"-shaped profile and having a swale running along the apex of the bed. A flexible watertight collection tube disposed within the swale beneath the membrane panels collects captured rainwater through pumps activated by water accumulating in the bed. Rainwater is thus automatically pumped into the collection tube as it accumulates on the membrane panels, preventing losses due to evaporation and percolation into the ground. The collected rainwater is stored in the storage tube and dispensed to an aqueduct system or tank trucks for transportation to the desired destination.
In the preferred embodiment the membrane panels axe transparent or translucent, allowing maintenance personnel to detect leaks in the panels by darkened areas of the ground visible through aerial inspection. The membrane panels may be marked with coordinate identifiers, allowing maintenance personnel to readily locate damaged areas from the ground. A
grid of maintenance corridors interspersed throughout the collection platform allows access to the membrane panels for maintenance and repair.
In the preferred embodiment the storage tube is provided with a sediment filtration system comprising catchment pits located near each end of the tube.
The swale is pitched slightly downhill from the centre to the ends of the collection tube, facilitating sediment collection in the catchment pits.
The present invention thus provides rainwater collection system, comprising a platform comprising a plurality of water-impervious panels, having a top surface for collecting rainwater and adapted to be laid over a bed having banks graded downward toward an intermediate region of the bed such that an apex of the bed is disposed along an intermediate portion of the platform, and an inflatable water collection tube disposed in a swale beneath the platform substantially along the apex thereof, the water collection tube being in fluid communication with the top surface of the platform through a plurality of pumps, wherein when rainwater falls on the platform the rainwater accumulates over the water collection tube and the pumps are actuated to pump the rainwater into the water collection tube.
Brief Description of the Drawings In drawings which illustrate by way of example only a preferred embodiment of the invention, Figure 1 is a top plan view of the rainwater collection system of the invention, Figure 2 is a cross-sectional elevation of the rainwater collection system of Figure 1 showing the water collection tube in a deflated (empty) condition, Figure 3 is a cross-sectional elevation of the rainwater collection system of Figure 1 showing the water collection tube in an inflated (storage) condition, Figure 4 is a partial transverse cross-section of the platform showing the preferred manner of anchoring the membrane panels, Figure 5 is a bottom plan view of a pump in the rainwater collection system of Figure 1, and Figure 6 is a cross-section of the pump of Figure 5.

Detailed Description of the Invention As illustrated in Figures 1 to 3, in a preferred embodiment the rainwater collection system of the invention comprises a platform 20 and a collection tube 40. The platform 20 comprises a plurality of water-impervious membrane panels 22 laid in abutting relation so as to render the platform 20 substantially watertight.
The platform 20 is laid over a shallow "V"-shaped bed 2 with banks 3 formed in the ground in any suitable area, preferably in a clay or other relatively dense base. The banks 3 of the bed 2 may be graded at a pitch of less than 1 °, or may be bowl-shaped or otherwise graded toward the longitudinal centre of the bed 2, but should be substantially smooth to avoid pooling of rainwater on the platform 20 remote from the collection tube 40. Preferably the panels 22 are composed of a lightweight, flexible plastic membrane material which may be clear, semi-transparent or translucent to allow for visual aerial inspection. The plastic is also preferably treated so as to be resistant to decomposition by ultraviolet light.
As shown in Figure 4 the panels 22 are laid in overlapping relation, with an anchoring portion 24 of each panel 22 buried to preferably a minimum of 3 feet to anchor the panel along its length. The edge 26 of the next abutting panel is heat sealed, welded or bonded to the upper corner of the anchoring flap 24 to render the platform 20 watertight.
In the embodiment shown each panel 22 is 103 feet wide ( 100 feet of exposed panel plus a 3 foot anchoring flap 24), and over 4,000 feet long. The particular sizes of the panels 22 and the number of panels used to produce the platform are a matter of selection according to environmental and topographical conditions and the amount of rainfall sought to be collected by the system.
The platform 20 is provided with a series of maintenance corridors 30 intermittently interspersed amongst the panels 22, which may be surfaced with gravel to accommodate maintenance trucks. A separate drainage system (not shown) is provided in the swale 4, described below, to remove runoff from the maintenance corridors 30.
At the apex of the bed 2 is provided a swale 4, which is essentially a ditch running longitudinally along the bed 2. The width and depth of the swale 4 is selected to accommodate the collection tube 40 in the fully inflated condition, which in turn is dependent upon the amount of rainfall sought to be collected by the system.
The collection tube 40 comprises an elongated watertight bladder preferably formed from a rugged, flexible and water-impervious plastic or rubber membrane formed into a sleeve and having ends 42 welded, bonded or otherwise suitably affixed thereto. The water collection tube 40 extends beneath the platform 20 along substantially its entire length, to collect rainwater captured by the platform 20 in the manner described below.
The platform 20 is anchored to the water collection tube 40 by a series of pumps 50, illustrated in Figures 5 and 6, distributed in substantially evenly spaced relation along the top surface of the water collection tube 40. The pumps 50, each having a waterproof casing 56, may be spaced apart longitudinally every 50 feet or so as in the embodiment shown, and are disposed circumferentially offset from the apex of the water collection tube 40 toward the side walls of the swale 4, for reasons described below. The top surface of the platform 20 is in communication with the interior of the water collection tube 40 through the pumps 50, as shown in Figure 5.
In operation, the water collection tube 40 is in the empty condition shown in Figure 2 after installation of the system. As rain falls over the platform 20 the rainwater runs down the panels 22 toward the swale and begins to accumulate above the water collection tube 40. The pumps 50, each with water level detectors (not shown), are actuated when accumulated rainwater rises to the level of the water detectors. Collected rainwater is pumped into pump inlets 52 and through pump outlets 54 into the water collection tube 40, which begins to inflate.

As the water collection tube 40 inflates it raises the central portions of the panels 22, creating troughs 36 along the side edges of the swale 4. The pump inlets 52 are preferably oriented toward the troughs 36, so the pumps 50 are activated by increasingly smaller volumes of water as the collection tube 40 inflates and assumes more of a convex profile.
Thus, even as the rate of rainwater collection decreases as the rainfall diminishes, the pumps 50 are able to continue pumping the rainwater into the collection tube 40. If desired the troughs 36, which are not directly supported by the ground, could be formed from a thicker membrane or reinforced with additional membrane layers.
Water is dispensed from the collection tube 40 through pipes 60 at one or both ends 42, into an aqueduct or other piping system (not shown) or into tank trucks, for transportation to the intended destination. The swale 40 is preferably graded slightly downhill, from one end 42 to the other end 42 if only one dispensing pipe 60 is used as in the embodiment shown in Figure 1, or if pipes 60 are disposed at both ends 42 the swale 40 is graded downhill from approximately the longitudinal centre of the tube 40, so that water will not pool in the collection tube 40 and sediment collected with the rainwater will flow toward the dispensing pipes) 60.
Sediment catchment pits (not shown) having coarse and fine filters for separating stones, plants, sand, sediment and the like from the collected water before dispensing, may be disposed upstream of or in communication with the dispensing pipes) 60. A bean (not shown) may be erected around the platform 20, or adjacent to those portions of the platform 20 which are subjected to winds, to reduce the accumulation of sand and debris on the platform 20.
The maintenance corridors 30 may be used to gain access to all portions of the platform 20 for periodic cleaning and maintenance. Visual inspection by aerial examination would also be conducted periodically, and any leaks in the panels 22 would be readily visible as darkened portions of the ground beneath the clear or translucent membrane panels 22.

Maintenance personnel would be directed to the affected area by reference to coordinate markings 28 on the panels, shown in Figure 1, corresponding to a map matrix representation of the platform 20.
It will be appreciated that although the platform 20 in the illustrated embodiment is laterally symmetrical, depending upon environmental and topographical conditions it may be appropriate in any particular case to have one side of the platform 20 smaller than the other. In such a case the water collection tube 40 would not be centred beneath the platform 20, but the apex (lower limit) of the bed 2 would still run along an intermediate portion of the platform 20 and the water collection tube 40 would still be disposed beneath the apex of the platform 20 in order to collect rainwater as it accumulates.
A warming system (not shown), which may be electrically or solar powered, may be optionally disposed on the bed 2 to melt snow in colder climactic conditions.
A preferred embodiment of the invention having been thus described by way of example only, it will be apparent to those skilled in the art that certain modifications and adaptations may be made without departing from the scope of the invention, as set out in the appended claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A rainwater collection system, comprising a platform comprising a plurality of water-impervious panels, having a top surface for collecting rainwater and adapted to be laid over a bed having banks graded downward toward an intermediate region of the bed such that an apex of the bed is disposed along an intermediate portion of the platform, and an inflatable water collection tube disposed in a swale beneath the platform substantially along the apex thereof, the water collection tube being in fluid communication with the top surface of the platform through a plurality of pumps, wherein when rainwater falls on the platform the rainwater accumulates over the water collection tube and the pumps are actuated to pump the rainwater into the water collection tube.