TOSC Comments on OCC Site

Occidental Chemical Corporation Site, Montague, Michigan

Comments on Site Cleanup Plan Submitted by Dr. Michael Dybas, TOSC Program/Department of Civil and Environmental Engineering, Michigan State University

Submitted to Tanya Cabala, Director, Michigan Office of the Lake Michigan Federation May 15, 2001

Amended and Expanded May 29, 2001

The TOSC Program has raised questions about the proposed remedies for addressing the contamination at the Occidental Chemical Corporation Site. Specifically, for Daramend biological treatment (W.R. Grace technology):

• Has the pilot study component of Site Scenario 2. (pp. 46-48, "Draft Corrective Measures Study," 9/15/00. Earth Tech, Occ-94) been undertaken and completed to the degree needed to "determine the site specific effectiveness and useful life of this technology" as described in the Technical Screen of Site Scenario 2 (p46, OCC--94)? Additional TOSC comments regarding the use of Daramend are detailed in the memo below to Ken Bardo, U.S. EPA, dated May 29, 2001. The report on the pilot study ("Final Report: Bench-Scale Daramend Treatability Investigation - Organochlorine Pesticide-Impacted Soil," prepared by EarthTech, May 2001) did not demonstrate that enhanced contaminant degradation had been achieved in the Daramend-treated samples when compared to the control conditions. Additionally, data on pH and ORP were not included in this report. Conducting site-specific treatability studies is standard protocol before selecting the use of any innovative or biological remediation option. Demonstration of effective remediation at a level significantly greater than the untreated control condition is a basic requirement to demonstrate effectiveness.

• It appears that WR Grace will issue a "guarantee" based on the "successful completion of the pilot study" ("Draft Corrective Measures Study"). Is the successful completion of this study a requirement prior to approving this technology? The terms of the guarantee are critical to evaluating the applicability of the technology. What is the nature of the guarantee? Will terms of the guarantee be defined based on the final Daramend report, and if so, will the guarantee hold Grace to performance better than the untreated controls, when the pilot study indicates that remediation under both treated and control conditions is similar?

• TOSC is concerned that acceptance of Scenario 2 with the planned contingency of in-situ capping "if the Daramend Technology proves ineffective" (OCC -94 p 59 paragraph 2 line 4) is also an acceptance of Scenario 1 (Capping) if the pilot study doesn't work. Will the public have additional opportunities to comment if indeed the fall back position of Capping is selected?

• Without the study results, TOSC has reason to question how Reliability and Implementability ratings of "very good" were achieved. Statements that raise concern include "the technology is expected to work as well for Mirex and C-66, but there is no actual study which demonstrates this fact, therefore the rating assigned is very good," (OCC-94 pp. 46 paragraph 4 last line), and "due to the questions unanswered by the absence of a pilot study, a very good rating has been appointed." These statements sound as if the lack of supporting data is a positive finding and leads to favorable ratings for the technology. Several additional questions about the pilot study are detailed in the attached memo to Ken Bardo, U.S. EPA. The results of the pilot study suggest that a rating of "very good" for the Daramend technology is not warranted.

TOSC has significant reservations about the use of BioGeoCheMix. We have not been able to find any information on the successful use of these products for PCB degradation. Our questions are:

1. For the BioGeoCheMix technology, site-specific demonstration of effectiveness is needed. The Technical Screen section of Scenario 3 in the "Corrective Measures Study for White Lake Sediment near Dowie's Point..." p 32 (11/1/2000, Earth Tech) appears weak, stating that performance will be excellent for in situ biological treatment in combination with capping. However, the lack of an effective pilot evaluation of the biological component calls into question if this is more than simply capping. PCB degradation under anaerobic conditions by native microbial community members has been observed under laboratory conditions (Vogel et al., 1987 and Tiedje et al., 1993) and in Hudson River sediments (Brown et al., 1987). It is possible that in situ biological treatment may be effective if the correct microbial populations are present and the correct conditions can be achieved. These conditions are methanogenic, that is, the produce methane (Tiedje, 1993), and the degradation of PCBs has been shown to be blocked under conditions that inhibit methanogenesis. It is assumed, therefore, that the use of BioGeoCheMix would stimulate methanogenisis, which may lead to capping problems as detailed below.

2. If there is no good evidence of biological PCB degradation, TOSC would be reluctant to see the biological component included in a "kitchen sink" approach, rather than a carefully engineered approach. Use of bioremediation in conjunction with a cap may cause contaminants to be mobilized and become bioavailable into the ecosystem. This can be created by biostimulation of microbial activity that does not break down the PCB's, and may create biological organic compounds that may solubilize PCBs (attached to lipids, micells, physical disruption due to methane/off gas production) etc.). If this would occur, the cap function would be even more critical and, therefore, the nature of the cap is a critical step to reduce these possible effects of enhanced biological activity. Further, the enhanced methane production described in item 1 for BioGeoCheMix may cause physical disruption of the cap due to increased pressure upon the cap. TOSC has not seen sufficient documentation regarding the cap to provide technical comments.

3. TOSC has asked for product-specific results from the manufacturer on use of BioGeoCheMix for PCBs. If strong evidence of degradation is indeed shown, and capping can be constructed to minimize mobilization, Scenario 3 may be valid. In the absence of this, the same requirement of a site-specific test for BioGeoCheMix, as was called for with Daramend, is recommended. The TOSC Program provides independent technical assistance to communities with contaminated sites.

   Inquiries should be directed to:

Kirk Riley
Department of Civil and Environmental Engineering
Michigan State University, East Lansing, MI 48824
Phone (517) 355-7493.