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Dredging Specialists Takes Aquatic Remediation to the Next Level.

Our Experience in Dredging and Dewatering: For over 35 years Dredging Specialist has been a hydraulic dredging contractor and builder of dredges and specialized dredging systems. 

  • For several years, we were the exclusive U.S. representative of Diemme of Italy, who manufacturer’s belt presses and plate and frame filter presses, which are used to dewater all types of water and solids slurries.   We provided plant installations, parts, and service.

  • We designed, built and operated a slurry mixing and pumping system that pumped to Geo-Bags on a Super Fund project.

  • We have dredged to a setup of five belt presses.

Aquatic Remediation Explained: These projects consist of dredging contaminated material from lakes, rivers and harbors.  The material is dewatered, left in place and capped, or hauled to a permitted landfill.  Both hydraulic and bucket dredging can be used.  The most common bucket used is the Cable Arm Bucket, which provides a flat level cut as it closes.  Click here to learn about the Cable Arm Bucket.

Belt presses and plate and frame filter presses are commonly used to mechanically dewater the material.  Geo-Bags are becoming popular for dewatering.  In Geo-Bags, the solids settle by gravity and the water leaches out through very small openings in the woven plastic material of the tube.  Click here to see many pictures of Geo-Bags in use.

These dewatering methods remove up to 98 % of the solids and the remaining fines are removed using clarifiers.   Polymer, and sometimes lime and alum, are mixed in the slurry, which causes the fines to form a flocculent which permits the material to be dewatered in presses and settle in clarifiers.  Sometimes the water must be further treated by passing it through sand or carbon filters. 

Problems and Advantages of Mechanical Dewatering:

  • Flow rates to a belt press can be 100 to 150 gpm and to a filter press 50 to 75 gpm.  This compares to up to 4,000 gpm from a dredge.  Thus, mechanical dewatering is very slow and many presses are needed.  In most cases, the capacity of a dredge cannot be fully utilized.

  • Presses will not accept solids larger than 1/8 inches.   Plus 1/8 inch solids must be screened out and dewatered separately.  Screens very frequently plug, causing the system to be shut down to clean the screens.  Dewatering the + 1/8 inch material is difficult.  Sand settles in the types of pumps used with presses and when it builds up it will damage or destroy the pumps.

  • Filter presses will get the material dryer and with less volume than any other method.  This can be an advantage if the material must be disposed of at a hazardous waste landfill with high dumping fees.

Advantages And Disadvantages Of Using Geo-Bags:

  • Dredge pumps will pass spherical solids up to 6 inches.  If it will pass through a dredge pump, it will go into a Geo-Bag.   However, long objects like sticks or boards and other objects that will not pass through a dredge pump must be screened out.   Problems of screening out oversize material when using Geo-Bags are far less than with presses.

  • Sand will not affect dredge pumps.

  • With several Geo-Bags pipelined together, they can accept flow rates up to 4,000 gpm.  Thus, projects are completed in much less time with far less equipment.

  • Total project costs are generally less with Geo-Bags compared, to using presses.

  • Geo-Bags require more land space than presses.

  • Material in Geo-Bags takes several months to dewater sufficiently for the material to be hauled to disposal.

The Dredging Specialists Aquatic Remediation System [ARS] Explained.

The ARS is the result of our over 35 years of dredging and dewatering experience.  The ARS is designed to be used with Geo-Bags.  To understand the ARS, the following is suggested.

  • Click here and read the article, “Is Polymer Effective In Dredge Pipelines & With Geo-Bags?”

  • Click here and print the schematic of the Aquatic Remediation System for hydraulic dredges.

  • Click here and print the schematic of the Aquatic Remediation System for bucket dredges.

The ARS Is A Combination Of Proven Methods And Equipment.

  • Geo-Bags are a proven method to dewater aquatic materials.

  • After reading the article, “Is Polymer Effective in Dredge Pipelines & With Geo-Bags?” you will understand that using polymer in dredge pipelines and in Geo-Bags is ineffective and a waste of time and money.  Polymer should be used after the Geo-Bags to flocculate the small amount of fines that go through the Geo-Bags so the fines will settle in clarifiers.

  • Clarifiers, along with polymer to cause flocculation are used in thousands of municipal water treatment plants worldwide.

  • If the fines are correctly dosed with polymer, there will be 100 % solids capture in the clarifiers.  However, sand filters are an available tool that can be used as a final filter, if they are needed.  Sand filters are used in thousands of municipal water treatment plants worldwide. 

  • The slurry Mixing and Pumping System used in the bucket dredging system was designed, built and successfully operated by Dredging Specialists on a Super Fund and another project, and is a proven system.

The Ability To Use Hydraulic Dredging Or Bucket Dredging Makes The ARS Flexible.

The decision to use hydraulic dredging or bucket dredging will be determined by the type of equipment available, the distance from the point of excavation to the dewatering site, the type of material, the amount of debris and other project factors.  Here are some options.

  • If the transport distance is short, say a mile, hydraulic dredging can be used. 

  • If the transport distance is, say five miles, bucket dredging with transport in scows and bucket transfer from the scows to the slurry mixer can be used.

  • If a bucket dredge is available and the transport distance is short, the slurry mixing and pumping system is placed on a barge tied to the side of the bucket dredge.  The material is excavated with the bucket, placed directly into the slurry mixing and pumping system and pumped in a pipeline to shore and into Geo-Bags.


The Aquatic Remediation System, [ARS], from Dredging Specialists, is a proven and economical system to remediate contaminated material from lakes, rivers and harbors.

For more information about how you can use the ARS on your project, contact Don Searles
217-259-2229  e-mail dredgesp@mchsi.com