|Alewife Study Group > W. R. Grace site > community feedback > Oct 28 2000, comment on W. R. Grace utility trench||| Search|
Dear City Councilors,
I sent the following comments to Amy Church at Haley & Aldrich in response to their recent report outlining a soil management plan for the proposed soil disturbance at the W.R. Grace site at 62 Whittemore Avenue. Grace is proposing to excavate a 5' x 5' x 500' trench for electrical lines in Zone 1 of their site, portions of which had been found in earlier investigations to contain very high levels of asbestos in soil.
My comments get a bit technical, but the two main points are:
1. Soil disturbance could be minimized by using a less obtrusive installation method, or eliminated entirely by putting the electrical lines overhead with the existing lines.
2. Grace will monitor for asbestos in air during the soil disturbance, but the action levels for stopping work and reevaluating soil management practices are ridiculously high. Ambient asbestos concentration in air would have to exceed 100,000 fibers per cubic meter before Grace would stop work. In contrast, the median urban background level of asbestos in air is 70 fibers per cubic meter, and the ambient concentration in the vicinity of an asbestos mine or factory is typically 2,000 fibers per cubic meter.
Feel free to contact me if you have any questions. I can be reached at firstname.lastname@example.org [note: for website, phone number replaced by email address].
- David Bass
The following are my comments and questions regarding the Public Comment Draft Report, "Utility Trench Excavation Release Abatement Measure (RAM) Plan/Asbestos Soil Management Plan" which Haley & Aldrich prepared on behalf of W.R. Grace & Co.
1. I appreciate the efforts by W.R. Grace to investigate the area and carefully plan in advance of the proposed soil disturbance. As you know, the neighbors take very seriously the possibility of mobilization of asbestos contamination during soil disturbing activities at the 62 Whittemore Avenue site.
2. Given the history of asbestos contamination at the site, why isn't Grace simply replacing the existing overhead electrical service an upgraded overhead service. With the prospect of soil disturbance so unsettling to abutters, isn't the installation of the electrical service in an underground trench unnecessarily provocative?
3. If Grace must put the cables underground, why dig a 5-foot square trench instead of using a soil saw (such as a "Ditch Witch" trencher) which would produce a much narrower cut? Electrical lines don't need to be below the frost line, so the excavation also could be shallower. The amount of soil disturbed could easily be only 5 to 10% of what Grace proposes to disturb with a 5-foot square trench.
4. Given that tremolite has been found at the site, would it not be appropriate to analyze at least some of the samples from the trench area using TEM?
5. Samples should be taken primarily from fill material, which is more likely than the lacustrine deposits to contain asbestos if it is present. In borings were both strata are present, each stratum should be sampled separately rather than composited.
6. The air monitoring procedure outlined on page 14 of the Public Comment Draft Report cites the OSHA 8-hour PEL for asbestos as the basis for its action level both for additional analysis of personal air monitoring units samples, as well as for work stoppage and management technique reevaluation based on the real-time fiber count from the MEI FM-7400. The OSHA 8-hour PEL of 0.1 PCM fiber/cc (100,000 PCM fibers per cubic meter) is a standard for industrial exposure and is entirely inappropriate for work adjacent to a residential neighborhood and playing field. Industrial exposure standards are often several orders of magnitude higher than standards for exposure to children. To put the OSHA 8-hour PEL number in perspective, the ATSDR Toxicological Profile states "close to an asbestos mine or factory, levels [of asbestos in air] could reach 2,000 fibers per cubic meter" and "the median concentration [of asbestos in air] in United States cities has been estimated to be 2.3 ng/cm [or 70 PCM fibers per cubic meter]."
7. The air monitoring procedure outlined on page 14 of the Public Comment Draft Report states, "If PCM analysis [of a personal air monitoring sample] indicates the PEL [of 0.1 PCM fiber/cc] was met or exceeded, the sample will immediately be analyzed using Transmission Electron Microscopy (TEM) . . . If TEM analysis indicates asbestos is present in the sample above a detection limit of 0.1 structures/cc work will cease and management techniques will be reevaluated." However, the ATSDR Toxicological Profile for asbestos states that "one phase contrast fiber per mL is about equal to 60 transmission electron microscope fibers per mL." So the action level of 0.1 TEM fiber/cc (100,000 TEM fibers per cubic meter) would correspond to 0.0017 PCM fiber/cc (1,700 PCM fibers per cubic meter). Whatever TEM action level is selected to stop work and review management techniques, the PCM action level to perform TEM analysis on the personal air monitoring sample should be at least a factor of 60 lower.
8. The Public Comment Draft Report report states on page 9, "Asbestos structures 0.5 to 5 microns in size were detected in 7 of the 10 air samples analyzed during the October 1999 program. The fibers were identified as chrysotile and amosite . . . The asbestos detected is consistent with low background levels published in the ATSDR Toxicological Profile for Asbestos." If in fact these results are reflective of local background levels, then they would form a reasonable basis for an action level: any significant increase above "background" would cause a work stoppage and management technique reevaluation. The maximum asbestos air concentration observed in the 1998 and 1999 air sampling events at the Grace site was 1400 TEM fibers per cubic meter. Using the rule of thumb of a factor of 60 difference between PCM and TEM concentrations outlined in the ATSDR Toxicological Profile, this would correspond to an asbestos air concentration of 23 PCM fibers per cubic meter. Therefore, reasonable action levels to stop work and reevaluate management techniques might be twice the maximum ambient background levels observed in the 1999 air sampling program (approximately 3000 TEM fibers per cubic meter or 50 PCM fibers per cubic meter). Note that the MEI FM-7400 claims to be equivalent to NIOSH Method 7400 (a PCM method), so the action level of 50 PCM fibers per cubic meter would be appropriate for the real-time fiber count.
9. Is there an AUL relevant to soil disturbance at the site? Have any been proposed?
Thank you for providing me this opportunity to provide input.
David H. Basss, Sc.D.
Contact the Alewife Study Group, North Cambridge Massachusetts, by email at email@example.com