Sediment can be collected as a core sample. Samplers can be within a boat or done by hand for many small ponds or lakes. Sediment samples can be tested for texture (sand, silt, clay), Munsell color, pH, and other parameters.
It may vary significantly, but you can find out. One way is to hire a professional, but if you just want a general idea there are many methods to probe. Depending on the sediment type you can use a piece of pvc pipe, rebar, broom handle, or other probe to push and work up and down throught the muck until you feel resistance that is the bottom. Some really fine, consolidated sediment may not let you probe all the water through it but you will have an idea of the depth.
A sediment survey or bathymetric survey can help determine the amount of sediment within a lake. Surveys involved finding the top of sediment and the bottom with a probe to determine the sediment depth in a particular location. That location can be used to determine an area to calculate a volume. Sediment is typically measured in cubic yards. Sludge is usually measured in dry tons.
The best way to determine the amount of silt in a pond or lake is to perform a bathymetric or sediment survey. You can set up a grid with a long tape measure and calculate the volume of sediment along with the depth for a general idea. A GPS or rangefinder with a probe can also be used to estimate the volume. The most accurate method is to have a survey completed by a professional. Otherwise, you may just be guessing until you find out when you dig it out.
Construction projects often have strict regulations about best management practices to implement so that soil is not lost from erosion from a site. The first call may be to the local issuing authority, usually your city or county, to check for a land disturbance permit number. If one has been issued, then there should be a set of plans that the inspector can check for compliance. If not, then the inspector may need to see if one was required before construction began. Preventing erosion is often the best practice but in most cases it is out of your control. Once sediment is in the stream silt traps may be an option to capture a portion of the sediment. A pre-construction survey of the lake sediment may be helpful in determining how much silt is being deposited over a period of time. EPD is the next call to file a complaint if the erosion is not eliminated and the permit is followed. The last result may be a consultant and/or lawyer to determine the best remedy. Dredging is often the solution to cleaning out the sediment from the lake or pond once it has been deposited.
Water exiting one property and entering another can be necessary but it also may become an issue. Often a conversation that leads into landscaping and grading for both properties may be the best solution. Ensuring the proper best management practices are beign used during construction and after can also eliminate erosion and excessive water runoff (check out Georgia’s Manual for Erosion and Sediment Control, the “Green Book” for ideas). Other resources like your local extension agent, NRCS agent, local issuing authority, and even EPD may be able to offer insight. If significant erosion is occurring and contributing to sediment ending up in your lake, pond, or stream it may be best to call a professional engineer or environmental consultant.
Some sludge and muck can be used as a soil amendment to be used as fill or land applied. Most sludge containing biosolids with levels of bacteria or metals must be taken to an approved landfill.
Dredging is one solution to remove sediment from in front of a nuclear or coal power plant water intake. Methods to minimize turbidity can be taken to reduce the risk of intake components. Schedules can be adjusted for best time to dredge for operations and water levels. Disposal of the sediment can be done on-site or exported.
Many water treatment plants are designed to store raw water within a reservoir prior to treatment. If your reservoir is losing capacity as a result of sedimentation, dredging may be the best solution. Dredging can remove the sediment without lowering the water level, and use of NSF polymers ensure that drinking water supply continues safely. Hydraulic dredging is a preferred method to dredge the sediment while the water remains in the reservoir.
