Frequently Asked Questions

You can measure the depth of water and sludge in a lagoon using a Sludge Judge®.  A sludge judge will allow you to measure the depth of water down to the surface of the sludge and then push through it to actually sample the sludge as well.  You can also use a rod or pvc pipe with markings to find the depth from the water to the top of the sludge.  The depth of sludge is the difference in the top of the sludge and the firm resistance of the bottom (usually clay, liner, or concrete).  A GPS or transect system can help you calculate the quantity of sludge in a lagoon. 

Silt bags or dewatering tubes are effective to dewater sediment from water.  The pipeline is inserted into the tube into a “sock” or port on the top side of the tube.  You can pump the tube up to its manufacturer’s recommended height of 6 or 8 feet in height.  Most sediments require polymer mixed with the silt to help it settle out quickly.  If the silt does not settle in the bag, the bag will seal off rapidly and not allow water to exit as fast you pump into it.  Once full the silt bag can remain until the silt is dry enough.  Then the bag can be cut open to remove the silt or it can be left in place. 

Dredging is a way to remove ash from a pond.  Coal ash or fly ash can be dug with an excavator or pumped with a hydraulic dredge from the pond. 

Dredging is the method to remove sludge from a lagoon.  If the lagoon can be taken offline and drained, then excavating the sludge may be an option.  Otherwise, a hydraulic dredge can pump sludge from the bottom of a lagoon to remove it and restore the lagoon’s original depth. 

Topsoil is best spread with a shovel and smoothed with a rake.  You can also use a tractor or skid steer for large amounts.  It does not spread well through spreaders used for seeding, or topdressers as it tends to stick to the sides and “bridge” over. 

Over time, ponds fill up with sediment (silt and muck) and most of the time vegetation starts growing within this sediment.  Dredging is a method to clean out a pond by removing the sediment.  It can be done by digging it out with an excavator or pumping it out with a dredge.  The sediment is usually completely wet and takes time to dispose of it.  It can be placed either nearby or hauled away to get rid of it permanently.  Dredging with excavators usually requires skilled operators to stay on a surface where they do not sink in the mud.  It is not typically performed with a bulldozer pushing mud out of the pond like traditional dirt work. 

Bio-slopes are designed to treat sheet flow from adjacent impervious surfaces such as roads. Stormwater sheet flow moves off of the roadway, sometimes through another filter treatment, over a bio-slope. Runoff is filtered through the bio-slope and the bio-slope media. The bio-slope media is composed a combination of coarse aggregate and permeable soil particles with high water retention capability. Bioslope mix may include aggregates, perlite, dolomite, and gypsum. The dolomite and gypsum components help treat stormwater and act as a buffer for acidic pH conditions and provide treatment for heavy metals. Perlite aids in the treatment of particulates, metals, and nutrients with it primary function being to retain moisture.  Treated runoff exits the bioslope system through a granular drain backfill material and sometimes with a perforated drain pipe. The overall effect filters stormwater to reduce the amount of runoff and improve water quality from runoff. 

Amphibious excavators have tracks that move over the top of large pontoons.  They are driven by hydraulic motors that turn gears at one or both ends of the tracks.  The tracks slide along tracks within the pontoons.  This allows the amphibious excavator to travel on land, mud, or water. 

A dredge alone usually is limited to about 2000 feet of pumping distance.  However, there are many factors that can limit or increase this distance.  Dredges along with booster pumps can essentially pump an indefinite distance but in most cases it becomes unfeasible economically. 

Standard size mini-ex’s can reach from 12 to 20 feet along the ground.  Bigger excavators can reach from 20 to 30 feet along the ground with 25 feet being the average distance.  Long reach excavators usually reach from 30 to 60 feet out.  The 60 feet reach is the standard size long reach excavator.  Specialized long reach excavators (not typically available) can reach 70 to over 100 feet.