CA2380599A1 - A temporary ice resistant boom for the control of the water flow in rivers or lakes - Google Patents

Abstract

A permanent structure with temporary use to generate a headloss in a river "HLG Boom" was developed to provide a means to control the level, the velocity or the discharge of the water in the river at a specific site. The potential applications for the "HLG Boom" is to modify the amount of water discharged into the out flowing rivers from a lake (Figure 1a), to increase or decrease the amount of water diverted from a river into a tributary or a canal (Figure 1b), or to increase the water level in a river, thus reducing the current velocity (Figure 1c).
The "HLG Boom" is designed using several self contained boom units connected together with chains to resist the water and generate. a headloss. Each boom unit consists of two steel pontoons joined with chains and where a rubber curtain blocks the gap in-between. The dimensions of the rubber curtain and the pontoons depend on the range of water depth and current velocity expected in the river. The pontoons are chained together and anchored at the boom ends and laid across the river.
The top pontoon (called "Pontoon 'T") is designed to provide the buoyancy that produces the desired headloss. The bottom pontoon (called "Pontoon B") is filled with water during the boom deployment to sink and rest firmly on the river bottom. The diameter of the Pontoon T, the length of the rubber curtain and its width are directly related to the desired headloss to be accomplished.
This "HLG Boom" can be designed to operate effectively during the dry season where the water discharge is low. For this case, the effect of the "HLG Boom" on the natural flow of the river gradually diminishes when the water discharge increases and the effect becomes negligible during flooding. If desired, the effect of the "HLG Boom" can be completely neutralized by sinking the top pontoon "Pontoon T" or by completely removing the "HLG Boom"
from the water.
The "HLG Boom" is designed so minimal retention of debris behind the boom can occur.
The "HLG Boom" is designed to be resistant to floating and grounded ice impact for use in northern rivers on a year-round basis.
The "HLG Boom" is designed so it can be deployed for any desired length of time. When the "HLG Boom" is no longer needed, it is removed from sight and re-deployed when it is required again. It can be removed by two methods by either re-floating all the boom units or by storing the HLG Boom under water (as described in Patent Application No. 2,252,197).
Conventional systems used to modify the river discharge or the current velocity, are usually permanent structures. These methods include blasting the rocky bottom or filling the river bottom with rocks, concrete or sheet piles. Control darn and others similar structures are also used.
Most of these options are permanent solutions that represent a problem when the water discharge increases. They are also costly to remove and can alter the water circulation in the river permanently. These options are also relatively expensive to design and build.
Approval of these types of structures requires comprehensive environmental impact studies, particularly in environmentally sensitive areas.

Description

Headloss Generator for Water Control in Rivers and Lakes.
Inventor: Razek Abdelnour and Andrew Liddiard Assignee: Fleet Technology Limited App. No.: ----Filed: April 15, 2002 Field of search: Civil Engineering/ River Hydraulics References cited:
ABDELNOUR, Razek, NICHOLSON, Corby., Patent Application No.: CA 2,252,197 "METHOD AND APPARATUS FOR
SINKING AND RE-FLOATMG ICE BOOMS"'. Filed November 9, 1998.

Specifications 1. This invention relates to a structure designed to produce a temporary headloss to control the discharge and the current velocity in rivers called a Headloss Generator Boom "HLG Boom".
When the structure is deployed, it produces a headloss, a resistance to the water flow that alters its velocity and its elevation. When the headloss increase at one river branch, the wter level upstream of the structure is affected thereby changing the current circulation in the river. Figure 1 shows the potential temporary applications for this invention:
a) modify the amount of water discharged into the out flowing rivers from a lake (Figure la, 1 ).
b) increase or decrease the amount of water diverted from a river into a tributary or a canal (Figure 1b, 2), c) increase the water elevation in a river, thus reducing the current velocity (Figure lc, 3).

2. A boom 4 consists of one or more boom sections (See Figure 2). Each section 5 consists of up to ten boom units. Each boom unit 6 consists of two pontoons, 7 &8, connected together with a rubber curtain 9 and three chains 10 to form the boom unit. In each boom unit, one pontoon rest at the bottom (pontoon B, 7) while the second pontoon (Pontoon T, 8) floats in the water at a fixed distance from the bottom pontoon that is equal to the length of the chains, 10, and rubber curtain,9 , connecting the two pontoons.

3. Each pontoon consists of a steel pipe with closed ends to provide the buoyancy. The buoyancy is needed for both pontoons. For Pontoon T, 7, the buoyancy is required to hold the rubber curtain, 9, the connecting chains, 10, and the Pontoon T, 7, floating in the water with a near vertical slope. For pontoon B, 8, the buoyancy is required to float the pontoon on the water surface for transport to t:he site and from the site during the removal.

4. The steel pontoons are between 5 and 15 m in length and between 0.4 to 1.2 m in diameter.
They are custom designed for each application and depend on the water depth, the current velocity and the desired headloss.

5. All Boom units are connected together with chains and shackles to form a boom section, 5.
The chain continues to the two anchors located on each side of the boom section.

6. An "HLG Boom" consists of one or more boom sections. Depending on the situation, more than one boom section may be placed to obtain the desired effect.

7. The "HLG Boom" is deployed from the nearest marina or other access to the river. The boom assembly is first earned out: on an access dock. Each boom unit 6 is deployed directly from a flat bed truck into the water with an appropriate crane. Each two consecutive boom units are attached together with a chain then gradually towed out to prepare for the deployment of the next boom unit, and so an. When all boom units are connected in water, the anchor chains are attached and the complete boom section is towed to the site.

8. To deploy the boom in place, all the Pontoons B, 8 are sunk, one after the other, by filling the inside completely with water. From a boat, a barge or from shore, as water is pumped inside the pontoon, its weight increases until it exceeds the buoyancy of the pontoon and sinks to rest on the bottom. The sinking i;> achieved by inserting a special fitting (as described in patent application No. 2,252,197) inside each of the bottom pontoons (Pontoons B).

9. The "HLG Boom" can be left in the water year-round, if so desired. The boom is designed to resist ice impact and shoving that occurs during the break-up in rivers. The boom will not resist the movement of the surface; ice and will not create or initiate ice jams.

10. The effect of the boom on the wager level may not be tolerable year-round.
The physical removal of the "HLG Boom" and its re-deployment can be very expensive. To minimise the cost, a method developed by Abdelnour et al, 1998, to sink and re-float the boom units will be applied.

11. To float the boom units, the valves of each pontoon B are opened to allow the water to escape under the air pressure inside the pontoon until the buoyancy of the pontoon exceeds its weight (the air will not be allowed to escape during the sinking process).

12. The procedure has been verified by carrying out tests on a I/16-scale model in the Laboratory.

13. Refernng to drawings, which illustrate embodiments of the invention, Photos 1 to 3 show the 1:16 model scale tests carried out to verify the concept.

14. Figure 1 shows the potential applications of the "HLG Boom".

15. Figure 2 shows a pictorial view of the "HLG Boom".

16. Figure 3 shows a three dimensional view of two complete boom units. This includes the Pontoon T, the Pontoon B, the rubber curtain and the connecting chains.

17. Figure 4 shows a cross section view of a unit for three waterlboom interaction conditions;
low water discharge, mean water discharge with boom in operation and while stored under water.

18. In Figure 5, the details of the attachment between the two pontoons, Pontoon T and Pontoon B, the rubber curtain and the chains.

19. Figure 6, shows a cross section of the boom during its deployment. Figure 6a shows the boom towed on the water surface. Figure 6b shows the boom during the sinking of pontoon B
and the last one; Figure 6c shows the boom while stored under water.

20. In Table 1, the buoyancy calculations are presented.

Claims (11)

1. An ice resistant permanent structure called "HLG Boom" to generate the required headloss in a river or a lake for a desired period of time.

2. The "HLG Boom" consists of two cylindrical pipes with closed ends connected together with a rubber curtain and chains to farm a boom unit. Several of these units form a boom section. One or more sections are used to create the desired headloss. The structure is designed for permanent installation at a specific location. Although the usage may be periodic or temporary.

3. The bottom Pontoon B 8 provides partial anchoring to the river bottom and the top Pontoon T 7 provides the buoyancy for suspending the curtain in the water column to resist the moving water.

4. The magnitude of the created headloss is related to the size of the top Pontoon T 7 and to the distance L between the two pontoons (Figure 3). The length of the chains and the rubber curtain determines the distance L.

5. One boom section consists of several boom units (up to 10 units) connected together with chains through attachment plates welded at the ends of the pontoons. The pontoon attachment plate at the end boom units are connected to two long chains that connect to two anchor points.

6. One boom may consist of one or more boom sections. The number depends on the desired headloss magnitude and the river width.

7. A barge and a boat that contains the equipment necessary for executing the boom sinking procedures are used to deploy the boom. A kit that includes a valve and associated piping and attachments, that permits the boom to be sunk (and later re-floated), is installed on all pontoons.
The equipment includes a water pump, an air compressor and other associated accessories (Abdelnour et al, 1998).

8. The pontoons B are filled with water to cause the boom to sink to the bottom. Once all Pontoons B are resting at the bottom and the anchor cables are connected to the anchors, the "HLG Boom" becomes ready for operation.

9. To re-float the pontoons, the valve installed on each pontoon is opened to let the water out.
Since the air is kept inside the pontoon during the water filling operation, the pressure displaces the water and the pontoon floats to the surface.

10. To disable the "HLG Boom", two options are available: The first is to remove the boom completely from the water by re-floating every Pontoon B 8. The second option is to store the boom on the bottom of the river to permit future uses. In this case, all Pontoons T are sunk as well. For this option, the water must be much deeper than the pontoon diameter so it does not present an obstacle to navigation.

11. The boom is designed to resist small waves without significant wear.