Alternate: Multi-utility Collaboration to Address Biosolids Management Challenges in the South Carolina Low Country

Summary This paper will present the results of collaborative inter-agency feasibility assessment for a regional program to manage residuals and biosolids for several public sector utilities in the South Carolina Low Country. The collaboration has been completed in multiple phases. The first phase (Phase I) involved six (6) public service agencies and covered ten (10) treatment plants representing the largest utility service providers in the South Carolina Low Country. The second phase (Phase II) involved four (4) agencies and six (6) treatment plants after two of the agencies exercised an 'off-ramp' option. The third phase (Phase III) involved three (3) agencies forming a new public agency authority the Charleston Regional Resource Recovery Authority (CRRRA) to manage a regional composting facility to be delivered under a progressive design-build-operate model. Background Most major wastewater treatment service providers in the Charleston, Berkeley, and Dorchester (CBD) counties currently dewater unstabilized wastewater treatment residuals and send the dewatered cake to either the Waste Management Oakridge Landfill or Berkeley County Landfill. Prior to the current practice of landfill disposal, many of these utilities had relied upon third-party end-users, such as GenEarth and Williamsburg Composting, to receive and process their solids. However, due to odor and operational concerns, these third-party operated facilities were unexpectedly decommissioned, leaving the utilities dependent upon the landfills for disposal of their solids. Recent landfill slope stability failures at landfill facilities in Georgia, believed to be caused by receipt and handling of excessive wet waste (e.g, dewatered sewage sludges), have caused regional landfill operators in both Georgia and the Carolinas to examine the ratio of wet waste (WW) to municipal solids waste (MSW) and explore options to reduce the WW:MSW ratio. As a result, the Oakridge and Berkeley County landfills have assessed utilities sending wet waste increased tipping fees for additional material handling and management costs at the landfill facilities. These increasing tipping fees, combined with other operational considerations, have been a primary driver for utilities to seek alternative residuals management approaches. As a result of the uncertainty the future might hold the utilities in the CBD region, representing six (6) organizational entities and ten (10) treatment facilities, formed a consortium to collaborate and explore regional alternatives for a collaborative biosolids management program: Phase I Initial Planning Assessment The Phase I feasibility assessment consisted primarily of the following major activities: -Estimates of Current (CY2020) and Future (CY 2050) Flows, Loads and Solids Quantity Estimates -Characterization and Quality of Dewatered Sludge Quality Factors -Regulatory Review and Benchmarking Assessment -Market Assessment for Residual and Biosolids Products in South Carolina -Alternative Development and Assessment Of particular interest in Phase I is the 'Alternative Development and Assessment' work where the following major approaches were assessed: -Thermal Hydrolysis and Mesophilic Digestion (THP+MAD) Class A Dewatered Cake End Product -THP+MAD with Thermal Drying Class A Dried Product -Fluid Bed Thermal Oxidation Ash End Product Preliminary system sizing was completed for each of the three alternatives examined and an AACE Class 5 level cost estimate developed for capital cost (CAPEX) for each facility. Operating costs were developed for each alternative and utilized, in combination with project flow loading rates, to develop lifecycle operating costs (OPEX) on a 20-year basis. Total lifecycle costs (TLCC), a combination of the CAPEX and OPEX, were developed for each alternative. Based on TLCC each of the alternatives had a similar expected cost with trade-off between higher CAPEX to achieve lower OPEX. Given similarity in TLCC for the alternatives the team used a multi-criteria assessment tool (CONVERGE) to assess both the cost and non-cost factors such as: -CAPEX -OPEX -Operability and Complexity -Maintainability and Complexity -Regulatory Compatibility -Environmental Stewardship -Long-Term Sustainability -Final Product Marketability The multi-criteria decision-making process from Phase I will be described in the results presented in the paper and presentation. Phase II Continuing Collaboration Development After the completion of the Phase I Feasibility Assessment, four (4) of the six (6) utilities in the consortium decided to continue efforts to further define a regional solution and develop a consortium-owned facility master plan. The Phase II efforts consisted of the following major activities: -Update the mass balance for the Phase I selected management alternatives for the reduced loading from the four (4) remaining utilities -Develop revised conceptual layout and process flow diagrams -Develop updated CAPEX, and OPEX cost estimates -Consider site location requirements for property assessment and acquisition -Consider the potential for addition of gasification or pyrolysis (post-dryer) for PFAS destruction -Develop a phased approach to facility build-out incorporating thermal drying as the first phase -Solicit interest of third-party owned and operated contract service providers to provide residuals management services via a public-private partnership (P3). This portion of the paper and presentation will describe the updated management approaches and the results of the solicitation of third-party owned and operated approaches for residuals management. As a result of this solicitation the utility partners decided to further consider development of a public-private partnership in the Phase III work. Phase III Formation of a Joint Authority and Solicitation for Facility Design-Construction-Operation Following completion of the Phase II work one utility partner withdrew from the collaborative and the three (3) remaining utility partners progressed into Phase III. Phase III included further evaluation of the third-party management approaches solicited in the Phase II work and consideration of composting as a viable management approach to produce a Class A stabilized material that would not have to be routed to a landfill for management. Phase III also included the formation of a separate legal entity, the Charleston Regional Resource Recovery Authority (CRRRA), that is jointly controlled by the three remaining utility agencies. The purpose of the CRRRA is to provide an entity to develop and operate a regional residuals management facility that will utilize Class A biosolids composting to stabilize and treat dewatered residuals from each of the agencies treatment facilities. Currently CRRRA is in the process of submitting proposals from entities that would be able to deliver under a progressive-design build-operate model a regional composting facility with a processing capacity of 100,000 tons per year. The facility will be owned by the CRRRA following the design-build phase work and will have an ongoing operating services contract for the receipt and processing of dewater residuals. Proposals are due in the middle of December 2022 with plans to evaluate and award in the first quarter of 2023. This portion of the paper and presentation will share the background behind the formation of the CRRRA including discussion of the legal formation of the authority and the governance structure of the jointly controlled agency. This portion of the paper will also share the process utilized for the solicitation of proposals from interested parties for the design-build-operate Class A composting facility including scoring and evaluation criteria utilized in the selection.