CLEANUP PLANNING AND DESIGN USING REMEDIATION MANAGEMENT ZONES: OZONE WITH ENHANCED BIOREMEDIATION CASE STUDY
James Jacobs and Roger Brewer
The fragmented approach for remediation planning often involves sequential remediation in different treatment zones rather than long-term planning using a comprehensive simultaneous remediation design in order to obtain site closure. One way to handle the simultaneous remediation approach is using
Environmental Hazard Evaluation (EHE). EHE includes the subsurface investigation phase and is based on the use of pre-approved, comprehensive,
Environmental Screening Levels (ESLs, referred to as
action levels or EALs in some states). The site investigation is designed to identify the presence or absence of each hazard on the basis of applicable ESLs, not simply define the vertical and lateral extent and magnitude of soil and groundwater contamination. This comprehensive approach helps avoid the need for time-consuming and costly remobilization for additional sampling in the future. In addition, it addresses the common concern from regulators that although the lithologic and chemical data have been collected, the site closure request has not been justified.
The results of the EHE are used to prepare site
Environmental Hazard maps that depict areas where soil and groundwater contamination pose specific environmental hazards. This is carried out by comparing soil, groundwater, and, in some cases, soil gas data to detailed ESLs for specific environmental hazards. Maps that collectively summarize areas of the site where specific environmental hazards are present are then prepared (i.e., based on a review of all contaminants of concern) and site conceptual models are prepared as well as potential exposure pathways. The hazard maps are then used with the results of the site investigation to divide contaminated areas into three Remediation Management Zones: Zone 1 (
source zone: aggressive treatment to remove priority environmental hazards), Zone 2 (
residual zone: passive treatment to address intermediate priority hazards), and Zone 3 (
attenuation zone: monitoring to ensure contamination is not spreading). Specific environmental hazards associated with each zone are clearly identified from the start of the project (direct exposure, vapor intrusion, leaching, etc.). The zone boundaries are either ESLs applicable to the targeted hazards or the treatment limits of particular remedial technologies. A San Francisco, California site will be examined where Remediation Management Zones were used in the planning and design phase of the project. Ozone was used in Zone 1 and enhanced bioremediation using oxygen infusion was used in Zone 2. The current status of this project will be discussed.
Presenter: James A. Jacobs, P.G., C.H.G., Environmental Bio-Systems, Inc., 707 View Point Road, Mill Valley, CA 94941; Telephone: 415-381-5195;
jimjacobs@ebsinfo.com
Roger Brewer, Ph.D., Hawai’i Department of Health, Hazard Evaluation and Emergency Response, 919 Ala Moana Boulevard, Honolulu, HI 96816, Telephone: 808-586-4328;
roger.brewer@doh.hawaii.gov
