Initially, numerous chemicals had been positively identified in both the soil and groundwater at the Park  During the previous investigations as well as ongoing work, KEMRON has tested soil and groundwater for Volatile Organic Compounds (VOCs), Semi-volatile Organic Compounds (SVOCs), RCRA Metals, Chlorinated Pesticides, Chlorinated Herbicides, and Polychlorinated Biphenyls.

The results of analytical testing were compared to the site specific risk reduction standards established during the CSR.  Chemicals observed above the RRS will be monitored during the remediation period to gauge effectiveness.  Once all concentrations are below the RRS the active remediation will be shut down and the two year monitoring period will begin (2010 - 2012).  The post remediation monitoring period is designed to observe long term groundwater conditions, concentration rebound, and plume migration.

Purpose

Based on data collected during the site’s investigation activities, an enhanced remedial alternative was developed to bring MW-6R into compliance with site specific Risk Reduction Standards (RRSs) in an acceptable timeframe. The current remediation approach consisting of groundwater extraction and treatment has been enhanced to more effectively remediate soil and groundwater in the vicinity of the well designed MW-6R. The need for the enhanced remediation is believed to be due to the observed structural geology at the site lending a pumping preferential pathway preference to the deeper more permeable fractures screened in the remediation wells. The remediation wells near MW-6R are screened across a shallow, low-yielding fracture, along with deeper, more productive fractures. Therefore, the system is likely drawing more groundwater from the higher yielding fractures that the low-yielding fracture.

Surfactant and Oxidant Injection

Pilot test studies are being conducted to determine an effective supplemental approach to soil and groundwater treatment utilizing surfactant and chemical oxidation treatment of the area.

Pilot Testing/Stress Test

A stress test is performed on injection wells and/ or existing remediation wells to develop an effective approach to surfactant and oxidant treatment. The stress test involves setting up mobile Dual Phase Extraction/Multi-phase extraction (DPE/MPE) to determine the hydraulic and vacuum radius of influence at the site. Data collected during the stress test will be used to estimate radius of influence and preferential pathways/fracture sets that will be influenced during the pilot test. Additionally, soil and groundwater is sampled for site specific contaminant treatability analysis.

 

Surfactant Injection/Extraction

The use of surfactants can serve to effectively mobilize petroleum free product and elevated concentrations of contaminants in soil and/or groundwater. The mobilized contaminants can then be more effectively remediated through processes such as pumping and/or vacuum remediation. The surfactant process is a three step process, initially consisting of (mobile) multi-phase/dual-phase extraction in advance of surfactant injection to dewater/drawdown the water table, creating cones of depression exposing the impacted soils (inclusive of, and notably, those impacted soils beneath the static water table), so that we can subsequently “fill” the dewatered areas/cones of depression with surfactant (allowing direct and undiluted contact with the impacted soils). Vertical distribution/vertical flushing of the impacted soils occurs when the water table recovers. The third step of the surfactant process entails the removal/capture of any remnants of petroleum free product, surfactant, contaminants and/or microemulsions utilizing the DPE/MPE system.

 

Chemical Oxidation Injection

The In-situ Chemical Oxidation (ISCO) process involves emplacing an oxidant to the subsurface through an injection point(s) allowing the oxidant chemicals to react with the contaminants in soil and groundwater, producing innocuous substances such as carbon dioxide and water. Many parameters in groundwater are monitored pre-injection and post-injection to determine the oxidant effectiveness, radius of influence, reactivity, and chemical changes in groundwater. ISCO is a proven technology for contaminant mass reduction of volatile organic compounds and is ideally suited to treat the area of localized contamination that exists at this site.