Bio-Polymer (B-P) trenches are installed for drainage, leachate collection, or recharge systems where in-the-dry installation methods are not feasible or where cost savings can be realized. B-P trenches differ from normal slurry trenches in two ways. First, the slurry used to support the trench walls during excavation is made from a biodegradable material such as guar gum or polymer. Second, the trench backfill is a pervious material such as permeable sand or drain rock. After completion of the backfill, the slurry filling the voids of the filter material is treated to allow it to biodegrade or break down. It is then flushed out of the granular material. Drains installed by the bio-polymer method are usually deeper than 15 to 20 feet and have achieved depths of nearly 70 feet. They are used when the groundwater or soil conditions would result in an unstable situation without a trench shoring system, or where contaminated groundwater exists. In the latter case, the B-P trench method eliminates the need for dewatering, thereby greatly reducing the necessity for costly treatment or disposal of contaminated water from dewatering operations.

The B-P methods have been used on numerous polluted sites to reduce the cost of remediation. B-P trenches have been used to install pump and treat systems, air sparging trenches, groundwater collection and reinjection galleries and groundwater barriers. B-P drains also have uses in civil engineering including applications such as toe or chimney drains for earthen dams, groundwater diversion trenches, and dewatering for slope stabilization.

The construction of complex drainage trenches (with multiple liners, pipes, and aggregate) can be made cost-effective with the Bio-Polymer trench technique, however there are a number of construction considerations which must be resolved. First, all structures placed in a B-P trench must be weighted to sink into place through the slurry. Standard manufacturer's recommendations are available for placing some types of pipes under water or slurry. Fabrics must be designed not to trap the polymer in its weave. In general needle punch fabrics are not recommended, whereas woven fabrics are better suited. HDPE liners can be placed in the trench using special frames, rollers, and other construction aids. However it is not possible to weld joints under the slurry. Often a complex design can be simplified by substituting well casings for manholes and flexible corrugated slotted drain pipe for rigid pipe.

A soil-bentonite or cement-bentonite cutoff wall can be used as a containment device in conjunction with a B-P drainage or recharge trench to eliminate the necessity of a HDPE liner in the B-P trench.

If you have an immediate or future application for any of our specialty construction techniques, please contact us. If you need additional information please e-mail us at: info@inquip.com, or call one of our offices.

Eastern Region: P.O. Box 6277, Mclean, VA 22106
TEL: (703) 442-0143, FAX: (703) 442-0188

Western Region: P.O.Box 2182 , Santa Barbara, CA 93120
TEL: (805) 687-2007, FAX: (805) 682-0396