2. Site Setting
2.2 Interim Measures
2.3 Geologic Setting
Conceptual Site Model, May 2014
Hartford Petroleum Release Site
Apex Oil Company, Inc. (Apex) has updated the light non-aqueous phase liquid (LNAPL) component to the Conceptual Site Model (CSM) for petroleum hydrocarbons present beneath the northern portions of the Village of Hartford, Illinois, referred to as the Hartford Petroleum Release Site (Hartford Site). The location of the Hartford Site is shown on Figure 1. The CSM is being updated in a step-wise fashion, starting with this LNAPL component to the CSM in accordance with the memorandum entitled Comprehensive Conceptual Site Model Framework and Timeline, Hartford Area Hydrocarbon Plume Site (Trihydro 2013c). The next two deliverables will provide updates to the CSM for dissolved and vapor phase petroleum hydrocarbons partitioning from the LNAPL. The final deliverable, the Comprehensive CSM, will compile all the information presented within the LNAPL, dissolved phase, and vapor phase components to the CSM, as well as additional information gathered subsequent to and as a result of preparing the first three deliverables. The final CSM deliverable will also include evaluation of any additional LNAPL recovery pilot tests performed at the Hartford Site.
As described in the Comprehensive Conceptual Site Model Framework and Timeline, Hartford Area Hydrocarbon Plume Site (Trihydro 2013), “the CSM will integrate information previously collected at the Hartford Site with an emphasis on further analysis and visual presentation of the existing data. In addition, further investigation and monitoring activities will be proposed to resolve data gaps or update previous investigation findings as needed.” The majority of activities related to assessment of the distribution, characterization, mobility, and recoverability of LNAPL performed at the Hartford Site were conducted between July 2003 and May 2006, and previously reported within the Active LNAPL Recovery System Conceptual Site Model (Clayton 2005) and the Active LNAPL Recovery System 90% Design Report (Clayton 2006). Assessment activities performed over this timeframe included installation of: (1) 109 borings for collection of cone penetrometer and laser induced fluorescence data (HROST-prefix), (2) 66 groundwater monitoring wells (HMW-prefix), (3) 17 piezometers and boring (HP-prefix), (4) 271 multipurpose monitoring points (MP-prefix), and (5) 260 vapor monitoring probes (VMP- and VP-prefix). LNAPL recharge and recoverability tests were also performed in 19 wells via multiphase extraction (MPE) and low flow dual phase extraction (LFDPE) between May and November 2005 (H2A 2006). After May 2006, more than 75 soil vapor recovery wells (HSVE-prefix) and 5 MPE wells (MPE-prefix) were installed across the Hartford Site. Additionally, 66 multipurpose monitoring points (MP-prefix) and 3 groundwater monitoring wells (ASW-prefix) were installed primarily to monitor the effectiveness of the soil vapor extraction (SVE) system and pilot testing to be performed in Area A. Accordingly, the majority of data that was used to prepare this component to the CSM was drawn from the historical assessment activities performed between July 2003 and May 2006.
This component to the CSM also incorporates more recent data collected since May 2006, including lithologic information from newly installed wells, routine LNAPL thickness measurements, and manual LNAPL skimming results. Additional laser induced fluorescence (LIF) data collected in 2013 to evaluate changes in the smear zone are also included herein. Finally, this component of the CSM provides an explanation regarding the first phase of additional LNAPL recovery pilot testing performed beneath Area A of the Hartford Site in late 2011 and early 2012 that was reported in the Light Non-Aqueous Phase Liquid Recovery Pilot Test Interim Report (WSP 2012). Specific elements evaluated herein include:
A three-dimensional (3D) model depicting the lithology and distribution of LNAPL within the subsurface was prepared as part of this component to the CSM. This model is used to depict LNAPL occurrence within the multiple hydrostratigraphic units beneath the Hartford Site. The model will continue to be refined as part of the updates to the dissolved and vapor phase components to the CSM.
1.2. DOCUMENT ORGANIZATION
This update to the LNAPL CSM is organized as follows: