Frequently Asked Questions

Engineered soils are blended, manufactured soils with specific ratios of components.  The sand component can is often specified by gradation, for example ASTM c33.  The topsoil component may include a certain percentage of organic matter, pH, or texture.  The compost component may have to include a certain percentage of organic matter or meet the USCC STA requirements.  Once the key components are acquired the best way to blend the components is with a precision blending system.  Each component must be measured by volume or weight (scaled) prior to loading into the mixing system.  It is best to do a large quantity or the whole project’s quantity at a single run so that the entire mix is homogenous with no variability.  Sampling the components and final stockpile of engineered soil will ensure that the soil is compatible with the project prior to installation.

Determine the characteristics of the sediment that you need to pump including the distance and vertical head.  Select a pump based on its pump curve that can perform sufficiently for the project.  Select an engine that has the power requirements for the pump.  Determine the weight required for the pump and engine.  Build the barge capable to float and balance the weight of the engine and pump.  Most portable barge sections are built in 4’, 6’, 8’, 10’, or 12’ widths for transport.  Attach a ladder and cutterhead capable of desired dredging depths and pump capability.

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.

Sludge can be dewatered with a belt press, filter press, centrifuge, and dewatering screens. 

The most common method to dredge a lagoon is an auger dredge.  Auger dredges are typically cable driven that are anchored along the shoreline.  The auger is usually 6 to 8 feet wide and turns to move sludge toward the center where the suction intake from the pump is located.  Sludge is pumped via a pipeline to be dewatered in drying beds, belt presses, settling ponds, geosynthetic tubes, filter presses, or other dewatering means.  The auger can be set to a specific depth or guided with wheels or guides to prevent damage to liners within lagoons. 

Muck can be as nasty as it sounds in your lake.  The way to remove muck from your lake depends on how much you have and what kind of muck.  Muck rakes can be used to clean up a small portion of muck that gathers along your shoreline or dock.  Pumping muck with small trash pumps may work a little but is generally not an effective means as it stops up with sticks and trash easily.  You also have to deal with the water you pump from the lake.  There are some chemical and biological solutions that aid in decomposing organic matter but not the dirt portion of muck.  There are even mats made to walk on it.  Ultimately though, the solution to remove muck is to dredge your lake.  Dredging can remove muck from any area and restore the lake back to the original depth.

Sedimentation is a growing problem in our lakes, ponds, and reservoirs.  Removing it can be difficult.  Dredging is one solution that can remove sediment efficiently and effectively.  The sediment can be disposed of nearby or transported off-site.  Dredging is done by either digging the sediment out or pumping it (sucking) from the bottom of the reservoir.  Once sediment is within a lake, pond, or reservoir dredging is way to get it out!

There are specific plans with most project outlined by engineers and architects specific to each project’s landscape.  However, the general idea is to place a [perforated drainage pipe, usually with a filter sock along the bottom of a small pond dug along that collects the stormwater.  The pond is typically 4 to 6 feet in depth.  The drainage pipe discharges outside of the pond but also has a T or connection for a vertical standpipe that will be above the surface level of the pond for overflow discharge.  The underdrain system is typically filled with #57 gravel and lined with a geotextile liner.  Above the gravel and drainage system the bioretention soil mix is placed usually 36 to 48 inches in depth and covered with a mulch layer.  During the installation process machinery and other equipment must not be used to compact the bioretention soil as it is installed.  This can be done with excavators positioned from the edge, slinger trucks, or in a manner that starts in sections and works your way out of the pond.  Select native plants are planted within the pond to uptake moisture and nutrients retained.  The inlets are lined with concrete or rip rap to prevent incoming runoff from eroding the edges of the pond.

Topdressing is a great way to level a lawn.  Applying a thin layer of sand or soil can help level the lawn.  Be sure not to apply too much depth at one time if applying on top of an established turf grass.  Use the back of a rake or a broom to smooth out the material in small areas.  For large topdressed areas, use a drag or a type of smoothing device (old fence, heavy board, etc.) to smooth out the topdressing sand.

Bioretention soil mix typically consists of sand, soil, and compost.  Some blends call for the addition of calcined clay products or mulch.  The mix can be determined in the plans by ratios of volume or a dry weight basis (which require some conversion).  Each component must meet certain specifications in addition to the final blend meeting criteria.  RSI uses large stockpiles of each component that has be tested by a soil lab to blend into a soil mix that is completely homogenous for consistency.  Each component is measured for an accurate blend.  The final bioretention soil mix is tested to make sure it meets the criteria for the project.  The blended soil can be delivered and placed into the cell or basin without contaminating it.  Mixing soil on-site can be a tedious process and limited to available soil that may not be suitable.  The worst-case scenario is for a soil to cause a system to fail.  RSI has decades of experience to make sure you have a quality bioretention soil mix that you can be confident will work effectively.