Alternate: Making Your Solids Plan a Solid Plan: Biosolids Planning in Uncertain Times

Gulf Coast Authority (GCA) owns and operates five regional industrial and municipal wastewater treatment facilities in the state of Texas. Like many municipalities in the United States, GCA experienced a sharp increase in solids disposal costs at three GCA facilities in the Houston area: the Bayport Industrial Wastewater Treatment Facility (Bayport), Washburn Tunnel Industrial Wastewater Treatment Facility (Washburn Tunnel) and Blackhawk Regional Wastewater Treatment Facility (Blackhawk). All three facilities use belt filter presses for solids processing, with the dewatered solids hauled to landfills for disposal. In November 2020, GCA engaged AECOM to evaluate alternative solids processing technologies and determine an economical, long-term strategy for each facility. A key component in this evaluation was to not only look at cost impact, but to also consider additional risk factors, such as the risk of new technologies and emerging contaminants, such as poly- and perfluorinated compounds (PFAS). The project evaluated over 35 solids handling technologies, organized into treatment trains by thickening, stabilization, dewatering, and post-dewatering. Initially, a long list of technically feasible solids handling technologies was created to evaluate all options. Fatal flaw screening was used to eliminate individual technologies from the list based on the criteria developed by GCA and AECOM, which included safety, regulatory risk, capital cost, operational complexity, etc. GCA and AECOM collaboratively used a paired-analysis criteria to develop a short-list of alternatives. The paired analysis process allowing a ranking of priorities for each facility. For example, one would compare reliability to operational cost and determine which is a higher priority. This process produced a ranking matrix that was used to further reduce the potential set of options for evaluation to be between five and seven alternative treatment trains for each facility. Alternatives were selected specifically to include options covering the full range of potential dried solids content. Capital costs and operating cost details were developed for each of these options, allowing a quantitative evaluation of each short-listed alternative. Life cycle costs were evaluated for each option with timeframes provided by GCA. The project team completed a thorough analysis to summarize the advantages, disadvantages, and capital and operating costs for the selected alternatives. Combined with the identified risks, this allowed for a further refinement of alternatives. For example, the unknowns of future PFAS regulations were viewed as a strong disadvantage of land application alternatives. Typical solids technology evaluations assume static conditions, i.e. a capital cost of $X and a solids disposal cost of $Y. The GCA and AECOM team wanted to develop a more helpful tool and created a sensitivity analysis based on tipping fee impacts, capital cost impacts and technology performance assumptions. An example of this analysis is provided in Figure 1. This sensitivity analysis provided GCA with an incredibly useful tool to assess not only the current most economical options, but also be able to identify when other options should be considered. For example, a thermal drying system may not be economically feasible now, but if the tipping and disposal costs exceed a certain amount shown in the sensitivity analysis, thermal drying should be considered. The presentation will provide an overview of the project evaluation that was conducted including impacts on risk, future regulations, and the sensitivity of the different options to the assumptions. The presentation will also include a summary of the steps taken since the completion of the memo including further optimization of the existing dewatering facilities. Beyond just the technical aspect of this project, it was a great example of how teams can effectively resolve conflict. Many projects start out well, but once out of the 'honeymoon phase,' tensions can rise, miscommunications can occur, or there can be an incident which results in the dissatification between parties. The opposite occurred on this project. A few weeks after kick-off, there was a misunderstanding on project scope. This resulted in the team diverging on actions and expectations. This was quickly identified, a 'stop work' was issued, and key members from all parties had a call to discuss. Within 24 hours of the issue being identified, it was completely resolved and the rest of the project was a textbook example of true partnership between parties who had never worked together.