2. Site Setting
4.1. LNAPL Properties
4.2. LNAPL Distribution
4.3. LNAPL Recoverability
4.4. LNAPL CSM Summary
6. Vapor Phase
Figure 7-1. Site-Specific Attenuation Factors
Conceptual Site Model, March 2018
Hartford Petroleum Release Site
Apex Oil Company, Inc. (Apex) has updated the Conceptual Site Model (CSM) for petroleum hydrocarbons present beneath the northern portions of the Village of Hartford. The Village of Hartford is a mixed-use community (including residential, commercial, and industrial uses) located in Madison County, Illinois on the east bank of the Mississippi River, approximately twelve miles northeast of St. Louis, Missouri. Three refineries were constructed adjacent to the northern portion of the Village of Hartford between 1907 and 1941, the Amoco Oil Refinery (currently British Petroleum facility), the Clark Oil Refinery (currently the Premcor facility), and the Shell Oil Refinery (currently the Phillips66 facility). In addition, a bulk petroleum storage facility was constructed north of the Village of Hartford (currently the Hartford Wood River Terminal Oil Company facility). Refining, storage, and transport of petroleum hydrocarbons continues to be conducted adjacent to and beneath the Village of Hartford associated with these refineries and terminals. In addition, numerous underground and aboveground petroleum pipelines connect the refineries and terminal to loading and unloading facilities on the Mississippi River. Numerous historical releases of petroleum hydrocarbons, referred to as light non-aqueous phase liquids (LNAPL), have been documented within or immediately adjacent to the northern portions of the Village of Hartford. Interim remedial efforts have been performed over the past five decades to recover these hydrocarbons from the subsurface. Discussions within this CSM will primarily focus on the current conditions beneath the northern portions of the Village of Hartford, hereafter referred to as the Hartford Site. Figure 1-1 presents the location of the Hartford Site, the surrounding refining and storage facilities, as well as the pipelines used to transport petroleum hydrocarbons. Appendix A presents a detailed map of the structures and monitoring locations installed at the Hartford Site. The map included in Appendix A depicts the effectiveness monitoring zones used to differentiate conditions across the Hartford Site, and other key features described herein.
This update to the CSM is being prepared as part of the final RCRA corrective framework for the Hartford Site. As such, the CSM primarily focuses on data collected during the past five years (2013 through 2017) in an effort to describe current conditions beneath the Hartford Site. Historical data (collected between 2003 and 2012) has been used to: (1) augment recent data in cases where conditions have not substantially changed (e.g., residual LNAPL distribution within the deeper hydrostratigraphic units), and (2) demonstrate changes in site conditions (e.g., depletion of dissolved phase petroleum related constituent concentrations).
The updated CSM has been used to divide the Hartford Site into remedial management areas as described in Section 8.0. The information provided herein (combined with additional data that will be collected as part of resolving data gaps described in Section 7.0) will also be used to identify potentially viable remedial technologies for each remedial management area. Once appropriate technologies are selected for a remedial management area, future bench scale and pilot testing will be performed, as necessary, to confirm the effectiveness of a selected remedial technology in achieving the proposed remediation goals and performance metrics described within the memo entitled, Proposed Multiphase Remedy Framework Remedial Objectives, Remediation Goals, and Performance Metrics, Hartford Petroleum Release Site, Hartford, Illinois (212 Environmental 2017c).
1.2. DOCUMENT ORGANIZATION
This update to the CSM is organized as follows: