Benchmarking and Front-End Loading Analyses

Earth Tech conducted front-end loading (FEL) and benchmarking analyses for five remediation projects at a refinery formerly owned and operated by Chevron in Port Arthur, Texas. The remediation projects all are being addressed under the RCRA Corrective Action Program and Texas Risk Reduction Rule 3. The five solid waste management units consisted of three lagoons containing oily sludges, a stormwater pond, and a former landfill.

Earth Tech conducted FEL analyses on the designs for each of the five corrective action projects to determine the “readiness” of those projects to go to construction. In conducting the FEL analyses, Earth Tech engineers and environmental scientists reviewed and critiqued site characterization reports, corrective measures studies, detailed construction plans, specifications, and treatability studies, slope stability studies, and other engineering analyses provided by Chevron. The FEL analyses entailed critical review of both the site definition and design status for the project. Earth Tech compared the level of definition for each of the five corrective action projects to other similar projects conducted by the petroleum industry.

For the site definition criterion, Earth Tech identified site conditions, design requirements or other uncertainties that have not been fully evaluated or defined. Earth Tech evaluated the degree to which the subsurface conditions – principally the geology and hydrogeology at the site – were defined during the investigatory stages of the project lifecycle, the degree to which the nature and extent of contamination have been defined, and the degree to which potential transport pathways have been evaluated from a human health and ecological risk perspective.

For the design status criterion, Earth Tech evaluated the level of certainty in the estimated volume of contaminated media that must be removed, treated, and/or contained in order to attain the remedial objectives. Earth Tech evaluated:

The comprehensiveness and completeness of the engineering drawings and specifications
The comprehensiveness and completeness of the draft contracting documents including the Request for Bids, the bid response form, the draft contract, and any supporting documents
The comprehensiveness and completeness of the project execution plan including communications protocols, requirements for construction QA/QC (CQA/QC), schedule, health and safety plans, permits, and notifications

Earth Tech also conducted benchmarking analyses of the projected costs and schedule for each of the five corrective action projects. The benchmarking analyses consisted of three components: cost analysis, contingency analysis, and schedule analysis. To conduct the cost analysis, Earth Tech used the RACER™ cost estimating system to develop independent, single-point estimates of the projected cost for each project. To conduct the contingency analysis, Earth Tech used its proprietary financial risk modeling system called RACER-DS. Earth Tech conducted a “what-if” analysis on each RACER cost estimate to identify the variables that have the greatest impact on the total cost. Earth Tech then developed probability distribution functions (PDFs) for variables that have the greatest influence on overall cost and project duration. Earth Tech then ran Monte Carlo computer simulations (typically 10,000 iterations or more) of each cost model to analyze financial risk for the project. For the schedule analyses, Earth Tech created spreadsheet models that define work elements called for in the Closure Plans, productivity of the crews that would conduct each work element, and projected duration of each work element.

After the schedule models had been developed, Earth Tech linked them to key parameters in the corresponding cost models. As quantities of work in the cost models changed, the duration of specific tasks in the schedule models changed commensurately. Output from these analyses was an integrated picture of the cost and schedule risk associated with each project. Chevron used these analyses to determine whether to authorize funding for each project, or whether additional characterization and design work was warranted.