Mine Reclamation through Residuals use and Poplar Plantation Establishment

Client: 
Lehigh Hanson Materials Limited

Product quality and cleanliness are paramount to aggregate production.  As part of processing, aggregates are washed prior to stockpiling and blending.  Used wash water is recycled by pumping the water into large retaining ponds, where sediment such as silts and clays settle gravimetrically.  The clean wash water is decanted and reused.

Over time, these sedimentation ponds reach capacity and are decommissioned.  The remaining material lacks the required nutrients and organic matter to sustain vegetation.  SYLVIS identified the use of biosolids on a sediment pond to improve soil quality, and the establishment of a short rotation hybrid poplar plantation to achieve reclamation goals and produce a valuable crop.

SYLVIS conducted a clonal trial to assess the growth response of several hybrid clones, selecting two clones based on the results.  The plantation consists of nearly 5,000 trees planted over approximately 10 hectares as 0.3 m or 1 m rootless cuttings.  The plantation is fertilized with locally generated dewatered biosolids and liquid biosolids which, in addition to providing nutrients and organic matter, are an important source of moisture and increase soil water holding capacity.  These poplar trees are expected to be harvested in 2022 when they reach 18 years of age.

The poplar plantation has created an established habitat for residing wildlife including owls, frogs, black bear, deer and coyotes.  Through SYLVIS’s efforts the Sechelt Mine Reclamation Program has been recognized with several reclamation awards since the inception of the program.  One of the most prestigious honors was the Jake McDonald Award for excellence in the reclamation which was awarded in 2010 by the Technical and Research Committee on Reclamation.  This marked the first time an aggregate mine was honored with this distinction.