Once a body of water is formed, nature goes about filling it in with sediments from runoff. Mother Nature desires a steady state which is a uniform level. Most ponds slowly become bogs and swamps before ultimately drying out to become dry land once again. This usually takes many years, but human activity often speeds up the process. Dredging out this material is a fast way to deepen a body of water and remove many layers of nutrient that feed sometimes rampant aquatic plant growth. There are options when considering how to dredging you pond and you should be aware of the different techniques and which one will be right for you.
Long reach excavation is very straight forward. A specialized back hoe is brought in to dig the material from the bottom of the pond. If the pond is of any size, it will need to be drained to reach all the areas of the bottom. The amount of material can be easily quantified so you are sure that your money has gone to a defined amount of material being removed. Some of the down sides are that you will loose the use of your ponds while it is emptied and allowed to dry out. The fish contained will have to be moved or they will perish. The shoreline area will most likely be torn up as the equipment is moved around and sediment hauled away. This shoreline will have to be restored which may take years and will add to the overall cost.
Hydraulic dredging is a technique that uses water mixed with the bottom sediment to move the material away. The footprint for this type of dredging is much smaller than using excavators. One point of access is all that is required limiting shoreline damage. Large amounts of material can be moved without loss of fish habitat or the need to stock the pond again. However, a retention site must be available nearby to allow the water taken with the sediment to flow back into the pond while holding back the solid spoils. This area is typically quite large as the transported material is typically 80-90% water with 10-20% sediment. Once dried, most choose to move the material away adding another step and cost to the process. Also, it is very difficult to quantify the material removed through this process to determine if the contracted amount of material was removed from the pond. It is only after the material has dried that an accurate measurement can even be attempted. This takes months to happen.
Another newer alternative is a paddle wheeled propelled hydraulic barge that utilizes a mounted excavator arm with a clam-shell bucket. It effectively becomes a floating excavator that can reach all areas of the pond to dig very precisely to remove sediment from around habitat and docks. It allows the fish population to remain untouched in the pond and has a very small footprint. The sediment is loaded into a barge to be transported to a loading site where an excavator transports the material from the barge into a truck to be hauled away. The amount of material removed is easily quantified since the material is not mixed with water and a truckload is easily measured. Because of the low impact and setup costs, this alternative can be used in affordable stages instead of an all or nothing option.
Consider what you need, what you can afford and your site requirements. With the options above you should be able to find a choice that fits your needs.
0 ความคิดเห็น:
แสดงความคิดเห็น