Geosyntec is providing a variety of engineering and permitting services at an active oil refinery in the San Francisco Bay Area. The Regional Water Quality Control Board (RWQCB) requires formal engineering closure plans for 12 inactive waste management units (WMUs) at the refinery facility, seven of which were also under U.S. Enviromental Protection Agency (USEPA) Resource Conservation and Recovery Act (RCRA) corrective action requirements.
These WMUs range from 0.1 to 46 acres in size, and were used historically to manage a wide variety of refinery waste streams such as crude oils and distillates, spent acids, oily sludges, and metals-bearing catalysts. The RWQCB directed the PRP Group to include the effects of sea level rise (SLR) in the engineering closure design for the five WMUs remaining to be closed. Geosyntec provided SLR guidance for closure designs due to their close proximity to the tidal influence zone of the San Francisco Bay and nearby surface water features.
Geosyntec's Scope of Services
To define the parameters for SLR impacts and develop SLR allowance estimates for engineering design for each of the closed WMUs, Geosyntec considered published literature on SLR, as well as policy and state and regional guidance documents. This was part of the groundwork for a vulnerability analysis for each of the WMUs that considers the direct and consequential effects of SLR, including (1) inundation by rising sea level; (2) flooding from a 100-year storm event; and (3) flooding and inundation from rising shallow groundwater due to potential influence of SLR on groundwater levels. Geosyntec also utilized high-resolution aerial topographic and imagery surveys to document recent king tide conditions to analyze and project potential flooding under future SLR conditions.
Based on the evaluation of SLR, Geosyntec developed guidance for establishing adaptive management strategies to incorporate in closure designs to account for potential SLR through the year 2100. Due to the uncertainties about the various factors influencing SLR, the guidance established SLR in the year 2050 as the design criteria for closure system components, with monitoring and adaptive management between 2050 and 2100.
Geosyntec's work on evaluating SLR and related impacts on the closed WMUs was important to ensure that wastes contained within the closed units are not released to human or ecological receptors as sea level and climate conditions change. With numerous techniques and guidelines for monitoring and potential facility modifications, Geosyntec's SLR guidance for the refinery integrates numerical modeling and empirical data sources into a logical system of prediction and adaptation methodologies. Our report was the first guidance of its kind to be accepted for a refinery by the Water Board in the state of California. The guidance is now being used to assess units that have already been closed but that may be vulnerable to SLR impacts.