US20080314901A1

US20080314901A1 - Method of securing elongated objects to a floating cover

Info

Publication number: US20080314901A1
Application number: US11/766,703
Authority: US
Inventors: Jason Jeffery Robert MacQueen; James Andrew Mills
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-06-21
Filing date: 2007-06-21
Publication date: 2008-12-25
Also published as: CA2635626A1

Abstract

A method of securing elongated objects, such as weights or floats to a floating cover. A first step involves providing a sheet form substrate. A second step involves forming elongated retention pockets on the substrate. A third step involves inserting elongated objects into the elongated retention pockets. This method allows thinner lower cost substrates to be used, while still facilitating secure attachment of weights or floats.

Description

FIELD

The present invention relates to a method of securing elongated objects, such as weights or floats to a floating cover, and a floating cover resulting from the method.

BACKGROUND

Floating covers have floats attached to provide needed buoyancy and weights attached to control slack and to protect against wind uplift. A gas collection cover is a particular type of floating cover. There is an increasing tendency to cover lagoons that release gas to atmosphere with gas collection covers. For example, sewage lagoons release methane gas to atmosphere. Sometimes gas collection covers are installed for environmental reasons. Sometimes gas collection covers are installed for commercial reasons, to capture and utilize the methane gas.
As gas collects under the gas collection cover, the gas tends to lift the gas collection covers off the surface of the pond or lagoon. Once lifted, the gas collection cover becomes vulnerable to wind damage, as it flaps over the surface of the pond or lagoon. Weights are, therefore, attached at spaced intervals to the gas collection cover in order to keep the gas collection cover in tension so it does not flap. The attaching of weights is presently a time consuming and labour intensive process. Previous gas collection covers have used polyethylene tubes filled with ballast as weights. These weight tubes were secured to the gas collection cover using straps that were bonded onto an upper surface of the gas collection cover.

SUMMARY

According to one aspect there is provided a method of securing elongated objects, such as floats or weights, to a floating cover. A first step involves providing a sheet form substrate. A second step involves forming elongated retention pockets on the substrate. A third step involves inserting elongated objects into the elongated retention pockets. This method provides an advantage of allowing thinner lower cost substrates to be used, while still facilitating secure attachment of weights or floats.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiment or embodiments shown, wherein:

FIG. 1 is a bottom plan view of a floating cover formed in accordance with the teachings of the present method.

FIG. 2 is a side elevation view of the floating cover of FIG. 1, showing elongated retention pockets where two substrates forming the floating cover are joined.

FIG. 3 is a side elevation view of the floating cover of FIG. 1, showing elongated retention pockets formed by bonding a strip of material to the substrate of the floating cover.

FIG. 4 is a top plan view, partially in section, of the floating cover of FIG. 1, showing the manner of insertion of weight tubes into the elongated retention pockets.

FIG. 5 is a top plan view, partially in section, of the floating cover of FIG. 1, showing the manner of filling weight tubes with liquid ballast while the weight tubes are positioned in situ within the elongated retention pockets of the floating cover.

FIG. 6 is a detailed cut away perspective view, partially in section, showing one end of a weight tube from FIG. 4.

FIG. 7 is a detailed side elevation view in section of the floating cover of FIG. 1.

FIG. 8 is a side elevation view of a floating cover with tubular floats positioned in the elongated retention pockets.

DETAILED DESCRIPTION

A method of securing elongated objects to a floating cover will now be described with reference to FIG. 1 through 8.
Referring to FIG. 1, in broad terms the method involves three steps. A first step involves providing a sheet form substrate 12. Where substrate 12 is to be used as a gas collection cover, substrate 12 is gas impervious. A second step involves forming elongated retention pockets 30 on substrate 12. A third step involves inserting an elongated object, such as weight tubes 38 or, as will hereinafter be described floats into elongated retention pockets 30. There are various ways in which the elongated retention pockets may be formed, two of which will hereinafter be described.
Referring to FIG. 1, a first step in the method involves providing more than one substrate 12. Each substrate 12 has a leading edge 14, a trailing edge 16 and opposed side edges 18 and 20, respectively.
Referring to FIG. 1, one approach to the second step of forming the elongated retention pockets 30 involves bonding leading edge 14 of a trailing substrate 22 to trailing edge 16 of a leading substrate 24. Referring to FIG. 2, leading edge 14 of trailing substrate 22 and trailing edge 16 of leading substrate 24 are placed in overlapping relation and two parallel spaced bonded seams 26 and 28 are used to secure trailing substrate 22 and leading substrate 24 together to form one of elongated retention pockets 30. Referring to FIG. 1, parallel spaced bonded seams 26 and 28 extend between opposed side edges 18 and 20 of respective trailing substrate 22 and leading substrate 24. This bonding step of attaching leading edge 14 of trailing substrate 22 to trailing edge 16 of leading substrate 24 is repeated, by joining in end to end relation a plurality of substrates 12 until a floating cover, generally indicated by reference numeral 100, of a desired length with a desired number of elongated retention pockets 30 has been formed. The bonding process can be performed with various bonding technologies. In field testing, beneficial results have been obtained through the use of a heat bonding process. During field testing, floating cover 100, was created along the shoreline of a lagoon by bonding a plurality of substrates 12 together. It will be appreciated that this work could have been performed at a remote fabrication facility and a completed floating cover 100 transported to the lagoon. It is believed that factory fabrication speeds installation and reduces field handling.
Referring to FIG. 3, another approach to the second step of forming the elongated retention pockets 30 involves bonding a strip of material 34 to substrate 12. Referring to FIG. 1, strip of material 34 extends between opposed side edges 18 and 20 of substrate 12. Referring to FIG. 3, opposed edges 32 of strip of material 34 are bonded to substrate 12 with two parallel spaced bonded seams 36. Referring to FIG. 1, seams 36 also extend between the opposed side edges 18 and 20 to form one of elongated retention pockets 30 between bonded seams 36.
For some installations, having elongated retention pockets 30 positioned where substrates 12 have been joined will be insufficient. This may be the case where substrates 12 come in long lengths, thereby requiring fewer joints. In such cases, one, or both approaches may be used to ensure there are enough elongated retention pockets to accommodate sufficient floats to provide floatation and sufficient weights to keep floating cover 100 in place when gas starts to accumulate under floating cover 100.
Referring to FIG. 4, a further step involves inserting weight tubes 38 into elongated retention pockets 30. Although weight tubes 38 may be pre-filled with ballast when inserted, for ease of handling it is preferred that weight tubes 38 be empty. Referring to FIG. 5, weight tubes 38 are shown as having been inserted into elongated retention pockets 30 empty.
A further step is illustrated of pumping ballast 40 with pump 42 into each of weight tubes 38, while weight tubes 38 are positioned in situ within elongated retention pockets 30 of floating cover 100. Weight tubes 38 are provided with fill ports 44 at each end. When filling takes place from one end, the one of fill ports 44 at the other end serves as a vent for the release of air. FIG. 6, details a cut-away view of one end of weight tube 38. Both ends of weight tube 38 are the same. Each weight tube 38 is closed at either ends. Depending upon the kind of material used, ends of weight tubes 38 may be closed with end seals 43. In the illustrated example, seals 43 were formed through heat sealing. Fill ports 44 are plugged after weight tube 38 is filled with ballast 40.
In the prior art, weights tubes were positioned onto gas collection covers with straps as it was deployed. With the present method, floating cover 100 can be fully deployed before the weight tubes are filled with ballast. This simplifies the deployment process. Once deployed, the filling with liquid ballast is relatively rapid. A further advantage of this teaching is that the weight tubes can be drained of ballast to simplify future cover replacement.
The liquid ballast 40 is selected based upon application requirements. For many applications water can be used. Water has neutral buoyancy when the cover is floating on water, but provides the required weight when accumulated gas physically lifts the cover from surface of the lagoon. In applications where greater weight is required, a slurry of sand and water, grout, or any other cementatious mixture can be used. Where freezing is of concern, liquid ballast can be selected based upon its ability to withstand freezing at anticipated temperatures.

Floating Cover

Referring to FIG. 1 floating cover 100, fabricated in accordance with the teachings of the method, consists of a substrate 12 having an upper surface 102, a lower surface 104, and opposed side edges 18 and 20. Floating cover 100 may be made from geomembrane materials. Continuous open ended elongated retention pockets 30 extend between opposed side edges 18 and 20. As described above, elongated retention pockets 30 are formed either by bonding strips of material 34 to gas impervious substrate 12 or by placing parallel side edge to side edge bonded seams 26 and 28 where one substrate 12 which is a leading substrate 24 is overlapped with a trailing substrate 22.
Referring to FIG. 1, floating cover 100 may contain a perforated pipe 46 contained within a perimeter 47 of floating cover 100. Referring to FIG. 7, perforated pipe 46 collects gas that is contained by floating cover 100. Gas may naturally collect in a gas space 48 between floating cover 100 and a body of water 50. Gas from gas space 48 then enters into perforated pipe 46. Referring to FIG. 1, gas travelling through perforated pipe 48 exits floating cover 100 through a non-perforated pipe 52. Non-perforated pipe 52 may carry any gas collected by floating cover 100 away to be processed. This has the advantage of allowing any gas that builds up in gas space 48 to be removed or collected, as well as reducing the gas pressure that may otherwise build up in gas space 48. Referring to FIG. 7, perforated pipe 48 may be wrapped in a geotextile sleeve 54, in order to protect perforated pipe 48. Floating cover 100 may be secured to a shore 56 of body of water 50. This may be accomplished by securing floating cover 100 in a trench 58. Floating cover 100 may be buried within trench 58. Other anchorage methods may be appropriate depending on site conditions.
Referring to FIG. 7, a liner 60 and an underlay 62 may be present on a bottom 64 of body of water 50. Liner 60 and underlay 62 may prevent the loss of water from body of water 50 to the surroundings. Liner 60 may be made from a geomembrane material, and underlay 62 may be made from geotextile materials. Both liner 60 and underlay 62 may be secured to shore 56 by burying liner 60 and underlay 62 within trench 58. Additionally, a staple 66 may be used to ensure that geotextile sleeve 54 holding perforated pipe 48 used for gas collection does not move during the installation process.
Advantages:
There are several advantages to using elongated retention pockets 30 over the prior art. Elongated retention pockets 30 are able to retain weight tubes 38 using lighter weight and less expensive materials to construct substrates 12. This is due to the fact that the weight of containing weight tubes 38 within pockets 30 is dispersed throughout the entire length of each elongated retention pocket 30. Traditional methods in the prior art would involve using straps which would require stronger materials to construct a gas collection cover with. In addition, elongated retention pockets 30 may be constructed within a factory. This is advantageous because it makes construction more consistent (using higher quality factory construction equipment) and installation in the field easier (no need to assemble cover 100 on site). Floating cover 100 may also be rolled up and transported to the field for easy installation and transportation. Furthermore, by containing weight tubes 38 entirely within elongated retention pockets 30, weight tubes 38 are protected from harmful UV exposure. This allows weight tubes 38 to be made from less expensive materials.
Variations:
In working with other types of floating covers, it has been determined that there is sometimes a need to secure floats to the floating covers. A variation of the present invention is to place floats into the pockets instead of or in addition to weight tubes. Referring to FIG. 8, there is illustrated a floating cover generally indicated by reference numeral 100. Floating cover 100 has pockets 130, formed as has previously been described. Instead of weight tubes, elongated floats 138 (also referred to as float) have been inserted into pockets 130. The purpose of this illustration is to demonstrate how the present method and apparatus can be used when flotation is of concern instead of or as well as the addition of weight. In many situations, there may be a mixture of tubular floats 138 and weight tubes 38 (not shown).
In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.
It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiments without departing from scope of the Claims.

Claims

1. A method of securing elongated objects to a floating cover, comprising:

providing at least one sheet form substrate;

forming elongated retention pockets on the substrate; and

inserting elongated objects into the elongated retention pockets.

2. The method of claim 1, the elongated objects being at least one of elongated weights or elongated floats.

3. The method of claim 1, the elongated weights being hollow weight tubes.

4. The method of claim 1, including a step of forming the elongated retention pockets by bonding a leading edge of a trailing substrate to a trailing edge of a leading substrate in overlapping relation with two parallel spaced bonded seams which extend toward opposed side edges of the respective leading substrate and the trailing substrate to form one of the elongated retention pockets between the bonded seams

5. The method of claim 1, including a step of forming the elongated retention pockets by bonding a strip of material in overlapping relation to the substrate with two parallel spaced bonded seams to form one of the elongated retention pockets between the bonded seams.

6. The method of claim 3, including a step of inserting the weight tubes into the elongated retention pockets before the weight tubes are filled with ballast and involving a further step of pumping ballast into each of the weight tubes in situ.

7. A method of securing elongated objects to a floating cover used for gas collection, comprising:

(a) providing more than one gas impervious substrate having a leading edge, a trailing edge and opposed side edges;

(b) forming elongated retention pockets on each substrate by bonding a strip of material which extends between the opposed side edges in overlapping relation to the substrate with two parallel spaced bonded seams which extend between the opposed side edges to form one of the elongated retention pockets between the bonded seams;

(c) bonding the leading edge of a trailing substrate to the trailing edge of a leading substrate until a floating cover of a desired length has been formed;

(d) inserting at least one of elongated weights or elongated floats into the elongated retention pockets.

8. The method of claim 7, involving inserting empty weight tubes into the elongated retention pockets during step (d); and

(e) pumping ballast into each of the weight tubes in situ.

9. A method of securing elongated objects to a floating cover used for gas collection, comprising:

(b) bonding the leading edge of a trailing substrate to the trailing edge of a leading substrate in overlapping relation with two parallel spaced bonded seams which extend between the opposed side edges of the respective leading substrate and trailing substrate to form elongated retention pockets between the bonded seams;

(c) repeating step (b) until a floating cover of a desired length with a desired number of the elongated retention pockets has been formed;

10. The method of claim 9, involving inserting empty weight tubes into the elongated retention pockets during step (d); and

(e) pumping ballast into each of the weight tubes in situ.

11. A floating cover, comprising:

a substrate having opposed side edges with continuous open ended elongated retention pockets extending between the opposed side edges.

12. The floating cover of claim 11, wherein a leading edge of a trailing substrate is bonded to a trailing edge of a leading substrate in overlapping relation with two parallel spaced bonded seams which extend between the opposed side edges of the respective leading substrate and trailing substrate to form one of the elongated retention pockets between the bonded seams.

13. The floating cover of claim 11, wherein strips of material extend between the opposed side edges of the substrate in overlapping relation, each strip of material being bonded to the substrate with two parallel spaced bonded seams which extend between the opposed side edges to form one of the elongated retention pockets between the bonded seams.