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February 21, 2003 Field Update

FIELD UPDATE 20
ACS NPL SITE RD/RA
February 21, 2003

For the past two years, Field Updates have featured remedial construction activities being performed at the ACS NPL Site.

A critical component of remediation is the coordinated monitoring program developed for the site that includes:

  1. monitoring the groundwater to assure that the public and nearby residents are not being impacted by site compounds
  2. monitoring the treated effluent and vapors from the on-site groundwater treatment plant (GWTP)
  3. performance monitoring to confirm that the remedial systems are working properly and to provide feedback data to assist in their operation, and
  4. health and safety monitoring to ensure safe conditions for people working at the ACS site, as well as for nearby residents.
  1. Groundwater Monitoring: The groundwater monitoring program monitors both the safety of the public and changes in groundwater constituents around the site. Groundwater samples are collected and analyzed from both the upper and lower aquifers from areas surrounding the site. In addition, nearby residential wells are sampled and analyzed annually. Results have consistently shown the residential wells are clean.
  2. Compliance Monitoring: Water samples are analyzed from the GWTP treated effluent to verify compliance with state discharge regulations. Air samples are also analyzed from the vapor treatment unit discharge to verify compliance with regulations.
  3. Measuring water levels at an ISVE wellPerformance Monitoring: Samples are also collected from the GWTP process line to monitor system performance. Water level elevations are measured across the site to monitor local and regional groundwater flow and to track performance of the perimeter containment wall. These water level measurements also document progress toward lowering water levels for optimum performance of the In-Situ Vapor Extraction (ISVE) systems. The photo on the right shows water level measurements being collected.

    The graph below depicts the average water level inside the barrier wall over time. The decreasing trend shows the progress in dewatering and contaminant removal achieved at the site.
    De-watering Progress in the On-Site and Off-Site Areas
    Contaminant concentrations extracted for treatment by the ISVE system are also monitored, as shown in the photo below.
    Performance monitoring of contaminant concentrations extracted by the ISVE
  4. Air monitoring while installing ISVE wellsHealth and Safety Monitoring: While installing the remedial system, realtime air monitoring is performed during drilling and excavating. Air meters are used to detect volatile gases and other potentially hazardous environments. The photo at right shows air monitoring being performed while ISVE wells are installed.


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