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FOLEY, HOAG & ELIOT

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January 26, 1988

E. Michael Thomas, Esquire Senior Assistant Regiona l Counsel U.s. Environmental Protection Agency Room 2203 J.F. Kennedy Federal Building Boston, MA. 02203

Re: Cannons Engineering Superfund Matter Bridgewater Remedia l Investigation Report

Dear Mr . Thomas:

At the request of the Technical Committee of the Four Sites Steering Committee , Malcolm Pirnie, Inc . has prepared comments concerning the "Final Report--Remedial Investigation , Cannons Engineering Corporation Site, Bridgewater, Massachusetts." Pursuant to the Technical Committee • s agreement with EPA, we submit these comments. We expect , in return, that EPA will promptly furnish us with a copy of the Feasibility Study prepared with respect to the Bridgewater Site. These comments should be read in conjunction with the November 12, 1987 comments prepared by Malcolm Pirnie, Inc. with respect to the Bridgewater Endangerment Assessment and submitted to EPA on November 17, 1987.

Submission of these comments is not intended nor should it be construed as an admission of liability or of any fact or a waiver of any right by the Steering Committee , the Technical Commi ttee , any member of those Committees, or any potentially responsible party . The comments do not necessarily reflect the position of a ny individual member of the Steering Committee or Technical Committee or any potentially responsible party and each member of those Committees and each potentially responsible party expressly reserves the right to assert positions different than or inconsistent with said comments during this matter or during any subsequent proceeding.

The Technical Committee understands that EPA is curre ntly considering procedures for me eting with potentially responsible parties and their consultants o r otherwise obtaining input from

E. Mic hael Thomas , Esqui r e Janua r y 26, 1988 Page 2

them with respect to the substance of the Bridgewater Feasibility Study. The Commit tee believes such procedures would be of benefit to EPA and requests that meetings between EPA and the Technical Committee be scheduled during the coming weeks .

We look forward to hearing from you concerning the Technical Committee's request to schedule meetings with EPA concernin the Feasibility Study.

~ur,

Robe r t So SanJ ff

RSS/lk

Enclosure

cc : Harry M. Carey, Jr o Members, Technical Committee

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l/26/88

Comments Prepared by Malcolm Pirnie·) Inc. With Resoect to Bridoewater Remedial Investiaation Reoort

At the request of the Technical Committee of the Four Sites Steering Committee, Malcolm Pirnie, Inc. has completed its review of t he "Final Report - Remedial Investigation, Cannons Engineering· Corporat ion Site, Bridgewater, Massachusetts" , dated May 1987. These comment s are directed to the r eport findings rather than specific comments on the data quality or study designs. Of particular importance t o t he design of any remedial action for this site were the following RI conclusions:

1. The highest concentrations o f organic chemicals detected on-site were confined to the shallow s urface soils (0 to 18 inches in depth).

2. The presence of low permeable fin e silty sand and silts has limited the downward migration of contamination in site soils.

3. The off-site domestic wells "'do not appear to be affected by chemical contamination detected at the aite."'

4. "'The total concentration of organic chemicals detected in the groundwater is not expected to result in a significant impact fr om contaminant migration beyond the site boundary ."'

S. "'The s urface waters do not appear to be an important migratory pathway at the site."

6. "'The conditions at the site which pose a concern to public health and environmental quality are: 1) contact with, and transport of , contaminated soils, sediments, and storage tanks by humans and wildlife: 2) consumption of groundwater from within the site boundaries •••• "

We believe the sixth conclusion does not propetly reflect site conditions as indicated by the RI data. The RI appears to overstate the extent of soil and groundwater contamination. The data collected in the RI suggest that contamination at the site results from localized sources, such as the drainage sump and storage tank. Spillage or leakage from these sources has

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resulted · i n "localized "hotspots". However, the low permeablity

of the soils together with the transport characteristics of the

compounds involved have limited the migration of those compounds

in the soil with the result that contamination is restricted to

local areas.

RESIDUAL SOIL CONTAMINATION

At the outset, it should be noted that the" soil data

collected during the RI resulted from a biased sampling design.

Sampling locations were selected based on screening with an HNu

and visible evidence of contamination. Accordingly, the results

should represer.t the worst case conditions on the site.

It is likely that the data represent a series of spatially

limited "hotspots" rather than the wide spatial distribution of

contami nati On shown in Figures 6 and 7 of the RI report. That

the distribution of contamination is limi ted to localized areas

is further supported by the nature of the contaminants found on

the site. PCBs, PAHs, and phthalates tend to bind to solid

particles and have limited mobility. Additionally, the low

permeable silty sands and silt appears to have prevented the

migration of the more mobile volatile organics. ·

Further sampling should be done to characterize the

distribution of the contaminants at the *hotspot• locations

identified in the RI so that the soils in these discrete areas

can be quantified and the appropriate soil rerr.edy can be

selected . If distribution of the contamination is confirmed to

be in discrete "hotspots", any on-site soil remedy can be

restricted to those discrete areas.

The residual soil contamination at the site, as previously

stated, is limited to the shallow soils. For instance, PCBs were

found in only 1 of 24 surface samples at a level above 10 ppm (96

ppm). No PCBs were detected in 10 of the 24 samples. The EPA

has established a 25 ppm clean-up standard for industrial and

restricted access zones (40 CFR Part 761, Polychlorinated

Biphenyls Spill Cleanup Policy: Final Rule, April 2, 1987).

While this "standard" technically does not apply to this site, it

may be cons i dered as an "other criteria" as it does reflect the

Agency's best th i nking relative to PCBs . This 25 ppm action

level was recently adopted in the Record Of Dec is ion at the Re­

Solve Site in North Dartmouth, Massachusetts . Any remedial

action should focus on the point where the 25 ppm level was

exceeded . We would recommend that further surface sampling be

done to confirm this one result and define the surficial area

where the 25 ppm action level is exceeded. PCBs were not

detected in any of the deeper subsurface soil samp~e~.

Total semivolatiles were reported at less than 1 ppm i n 22

out of 26 surface soil samples. We reviewed Records of Decision,

finalized before January 1987, for sites with similar Wecontamination to determine previously used action levels.

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f ound that quantita t ive action levels were established for t wo sites : United Creosoti ng , Texas a t 100 ppm of PAH : and Syncon Resi ns , New J e r sey a t 100 ppm Base Neu t ral s . At the Bri dgewate r site , the f our sur face soil samples with "measurable" t o tal semivol atiles were:

- B-2 3l. 9 p pm - SS-lD 13 . 9 ppm - E- 5 34.7ppm - F- 6 23 . 8 ppm

These data support the conten t ion that site contamination is limited to l oca l "hot spots" and t hat the l evels are l ower t han ac t i on level s employed at othe r Supe r fund sites .

Total volatiles in surfa ce soils exceeded 1 ppm in only eight out of- 26 surface soil samples . The maximum level reported in the subsurface soil s was 0. 53 ppm at MW-3 . At depths greater than two feet soil, total volatile levels were less than 0.15 ppm. This shows that the VOC compounds, which are the most likely to migrate, are be i ng confined to localized areas near the gravel surface by the low permeability of the silt sands and silt underlying the site. This distribution is similar to the distribution found with respect to the semivolatiles.

GROUNDWATER CONTAMINATION

The groundwat£r data suggest that groundwater contamination results from locali "ed areas of contaminated soils. Contamination was consistently found only in wells which were located near the "hotspots" and screened near the ground surface. Wells outside of the soil "hotspots" and/or screened in the bedrock do not show significant groundwater contamination.

Ground water samples were taken on three occasions during the RI and supplemental RI. The RI report states that the results were extremely variable. The only wells that showed consistent contamination were MW-2 and H-8. The contamination in HW-2 was attributed to the localized impact of the drainage sump, WS-1. The source of contamination at HW- 8 was not determined. However, the monitoring well soil data ind i ca t e possible localized soil contamination. In addit i on, no significant contamination was detected in MW-ll which was located about 100 feet downg radien t from HW-8 .

Generally , only two compounds appear t o have exceeded t heir Maximum Contaminan t Level s (MCLs ) i n t he samples collect ed from t he monitoring wells. The two compounds are benzene and

!~~~~~~~~e~~=n~c~~r=~~!sa~~e~w;:· st:~!~ea~~:e~C~s1~~!~i=~~arently condition . If t he "hotspots" of soil contamination are r emoved, the groundwater contamination will improve. It was the Rl

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conclusion that .. as these chemicals migrate off-site, the concentrations are expected to be attenuated by dilution and dispersion in groundwater ...

RECOf:'.MENOATlONS

The scope and nature of any remedial action at this site is contingent on the actual dist.ribution of contaminated soil. The vertical and horizontal distribution of contaminants found in the RI data, the biased sampling design used in obtaining that data, and environmental transport characteristics of the contaminants­-all indicate that soil contamination is probably distributed in spatially limited .,hotspots" rather than the widespread distribution suggested in the RI 's conclusions. Additionally, analytical results from monitoring well samples do not indicate significant degradation of groundwater under the site. The proximity of the groundwater contamination to local areas of s.oil contamination indicates that remediation of localized areas of contaminated soil should eliminate the need for remedial action for groundwater.

Additional sampling is needed to accurately cha racterize the apatial configuration of what appears to be limited soil contamination. EPA's evaluation of remedies should give careful consideration to the generally low levels of contamination found and the likelihood that contamination is limited to local areas.

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