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
davidbass@alum.mit.edu [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.
Sincerely,
David H. Basss, Sc.D.
Contact the Alewife Study Group, North Cambridge Massachusetts, by email at information@alewife.org