Alabama Soil and Water Blog Spot

  Polyacrylamide can be used in different forms to flocculate suspended soil particles and reduce turbidity.  One such form is a polymer block or log which is used in channelized flows or other concentrated flows. These can be used in flows that are gravity fed or created by pumping or other mechanical devices. Polymer logs are solid forms that slowly release polymer into the water stream binding sediment through flocculation. It is very important to understand how to properly use this type of flocculant to set up correct application for desired treatment.  Here are a few suggestions offered by Seva Bray of Applied Polymer Systems, Inc. Site specific testing is always suggested to ensure the correct log is selected that will meet NTU, TSS, and other discharge limits. (Reaction time is also found from the sample and this will determine treatment time needed before discharge) Polymer logs must be placed directly in the flow of water so there is...

  Inlet protection at stormwater manholes (drop inlets): One place on an active construction site that you definitely want to keep coarse particle sediment out of is the stormwater sewer manhole inlet.  Sediment in a storm sewer creates headaches. The Inlet Protection at these locations can be “built” or “bought”.  Built inlet protection as the term implies is constructed with conventional building materials and can be made from a silt fence like installation, straw wattles, sand bags, etc.  I’m not sure of how many “bought” or manufactured inlet protection devices there are for a manhole inlet, but one that you see a lot on construction sites is the domed inlet protection device by Silt Saver.  While this is not an endorsement of the product, I just want to make sure that everyone understands that there are still Do’s and Don’ts associated even with a simple and effective device like the domed inlet protection by Silt Saver. This device not only is effective ...

  It is often amazing how terms tend to “catch on” over time.  Take for instance the term “Silt Fence”.  While it does resemble a fence, it really has very little to do with silt.  From what we know today about a Silt Fence, it should really be called a “Geotextile Coarse Particle Sediment Barrier Impoundment Fence”.  This is a mouthful, so I guess Silt Fence is OK.   Here's what we know about Silt Fences: They should be installed in a manner to pond runoff, either on the contour, in a j-hook, or a c-configuration. Ponding water allows for coarse particles to settle from suspension. Clays and fine silts tend to stay in suspension a very long time. Silt Fences alone do not really reduce turbidity. The design runoff volume should be less than the storage volume available behind the fence. The runoff from a construction site will cause the geotextile to “blind” or clog and drastically reduce the flow-thru over ti...

  A lot of construction projects require drainageways to cross under a road.  We must always remember that there are many aquatic organisms that need to travel the drainageways even in intermittent streams.  If your culvert outlet has just a minimal overfall, small aquatic animals will be blocked from their migratory paths needed for their lifecycle.  If possible, think about using larger culverts that are properly placed to avoid overfalls, bottomless culverts which allow for the stream bottom to cross under the roadway, or even a small bridge.   Alabama is number one in the nation in Freshwater Fish Biodiversity  and we all should want to keep it that way. Perry L. Oakes, PE Erosion & Sediment Control Program Coordinator Alabama Soil and Water Conservation Committee

  Anyone who knows me knows that my wife and I spend time in Missouri visiting family. While there recently I snapped this picture. The picture emphasizes the importance of what vegetation needs to survive. While this yard is mostly bermudagrass and crabgrass, the stand of vegetation is very good except where the trampoline resides. The area under the trampoline is treated like the rest of the yard with little to no fertilizer and the same amount of rainfall since rain goes through the trampoline fabric. There is no foot traffic from grandkids in this area. However, direct sunlight does not occur and over a period of time the vegetation has died.  So the moral of this Tip is that the vegetation we use on our construction sites needs adequate sunlight to be successful, and that if you have one of these trampolines in your yard, periodically move it around to avoid this from happening. Think about this when planning vegetation on slopes that may not face the sun or on the shady ...