Inventory of Residuals and Synergistic Use Opportunities

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King County

The Resource Recovery Section of Washington state’s King County sought a biosolids and residuals use opportunity that promoted synergies in residuals management with other King County departments.  The intent is an operational demonstration project that demonstrates the Resource Recovery Section’s mandate to promote the sustainable and innovative use of biosolids and further the goals of promoting carbon sequestration, cost reduction and internal recycling of residuals.

To further these goals, SYLVIS and King County developed a scope of work to develop an inventory of residuals generated by King County and to identify opportunities for co-management of the residuals.  SYLVIS provided examples of opportunities for residuals use to increase awareness, educate and facilitate discussion within the County with respect to option identification.  Based on our extensive experience and expertise in residuals management, SYLVIS provided information on the beneficial use of residuals in landfill closure, mitigation of fugitive methane emissions, carbon sequestration, land reclamation, marginal land conversion, forest fertilization and horticultural applications.

As participation from multiple departments within King County was desired, SYLVIS created and disseminated a questionnaire to determine what residuals the County manages, how the residuals are currently being managed, the volume of residuals requiring management and new opportunities for co-management of residuals.   SYLVIS followed-up on the questionnaires with individual conversations with King County staff and summarized the results in a technical memorandum.

The work SYLVIS completed in developing an inventory of residuals and use opportunities formed the foundation for moving forward with establishment of a carbon sequestration project that demonstrates the beneficial co-management of residuals generated by various King County departments such as Roads, Parks and Forestry.  Residuals identified include biosolids, road and street sweepings, construction debris, wood waste, erosion event soil and vegetative debris from storm events and land clearing.

SYLVIS continues to work with King County to implement operational demonstration sites within King County that utilize two or more residuals for carbon sequestration.