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'·· James F. Murphy, Jr.

Assistant Vice President

Polyfibron Divi1ion

W. R. Groce & Co. 55 Hoyden AvenueAugust 31, 1989 lexington, Moss. 02173

(617) 861-6600

Hr. Wayne Robinson, Remedial Project Manager u.s. Environmental Protection Agency Waste Management Division HSV-CAN 5 J.F.K. Federal Building Boston, HA 02203-2211

Comment Letter to EPA:

At the Acton/EPA town meeting on August 14th. 1989 there were a number of concerns voiced by the towns people regarding present, and particularly future,risks involved with the closure of the W.R. Grace site.

We would like to present comments that we believe will alleviate these concerns.

The basic premise of the site closure plan is to remove future risk to Acton residents from contaaination on the W.R. Grace site. This will be achieved byremoving all contaminants from any location which might impact present or future Acton drinking water.

After the contaminants are moved from their present locations in the lagoons to the other side of the North-South groundwater devide west of the landfill location, they cannot impact the drinking water of the present Assabet Wells #1 and #2 or the future Assabet Well 13 (at the location of the WRG 13 well). This would be the case even if the landfill was left without a final cover (cap), as is shown on the attached computer simulation, Fig. 1. This particle trackingsimulation represents the travel of any contamination from the uncovered landfill and is based on the ground structure and flow characteristics from the CDM three dimentional computer model. What this shows is, that with Assabet #1 and 12 wells and the future Assabet 13 well operating at normal capacity, no contamination from the landfill would be drawn into the wells, even if the landfill were left uncovered or ' if there was a failure of a landfill cover. We will, however, be following the conservative approach of covering the landfill with an impervious cover and monitoring it for performance.

This removal of the contaminanats from the aquifer impacting the drinking water wells is accomplished by excavating all the sludges and contaminated soil from the waste sites, solidifying them, and putting them on "the other side of the hill" on the landfill.

To insure that no harmful contamination is left behind, the EPA and DEP have imposed soil cleanup levels for the soil left in the. excavated empty holes. These very low clean up levels are set to insure that Maximum Contamination Levels (MCLs) in the groundwater will not be exceeded. The fact that this is accomplished will be established in two ways. The first will be soil analysisin the empty holes to confirm that contamination in the soil does not exceed thecleanup levels. Then as a final check that the clean up levels were properlyset, the groundwater will be analyzed to insure that MCLs are not exceeded.

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MCLs have been set by the EPA to ensure that, with a margin of safety, drinking water will be safe.

Questions at August 14th, 1989 Meeting

In light of the premise of the site closure plan stated above, we would like to try to answer the following questions from the August 14th meeting.

~ - Landfill Questions... 1. question - The cap covers the landfill but what happens to the waste that is

underneath, in contact with the ground.

Answer - At the present time, contaminants from the waste in the landfill form a narrow plume in the ground water, that flows to the south east.

Cam~ridge Analytical Laboratory has done laboratory experiments, using soil from this area. These experiments demonstrate that all contaminants except chlorinated solvents (VC & VDC) biodegrade rapidly to C02 and water and disappear from the plume. This is confirmed from sample analysis of wells downgradient of the landfill which indicates that aromatic solvent contaminants such as benzene, toluene, and ethylbenzene disappear from the ground water after about 600 feet down gradient of the landfill. The contaminants that biodegrade aore slowly (such as the chlorinated solvents vinylcbloride and vinylidene chloride) have not been detected in the Assabet River as shown by over 30 sampling analyses from 1983 thru the present time.

,--­__) As stated above, computer simulations have shown that this contaminant plume

would never impact the Assabet Wells even if the landfill were not covered as proposed in the closure plan and the Aquifer Restoration System had been shut down.

After the impervious plastic cover is put on the landfill, no new contamination will flow to the groundwater plume once the rainwater in the landfill drains out. From past sampling data this "drying out" process is expected to take six to twelve months. Without rainwater to transport the contaminants, they will not move into the groundwater. The contaminants in the material in the landfill will continue to biodegrade, but with a cutoff of oxygen in the rain water, the rate will be extremely slow. There will also be some horizontal diffusion of these contaminant but this too would be so extremely slow, that there would be no detectable impact on the surrounding environment.

2. question - There were questions about the time frame for capping of the landfill and other questions on the impact of any subsidence of material in the landfill and subsequent da~age to the plastic cover. Since these questions are related they will be answered together.

Answer - Consultants (Haley & Aldrich) advise us that the majority of the compression of landfill material, due to loading, takes place fairly quickly (a few weeks or at most, a few months). Any compression after that time will be relatively small and is unlikely to damage a plastic cover. On the

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basis of this advice, we plan to place all of the solidified sludge and all of the fill, up to the location of the plastic cover and then wait six months before installing the plastic cover. This should allow sufficient time for the initial compression of the landfill material. After the plastic ~ver 1~ in place, the uniform layer of top soil and loam, for the vegative cover, should not cause differential compression of the landfill material.

Subsidence due to corrosion of metal objects in the landfill should be reduced once the plastic cover is in place. Corrosion of metal, as well as biodegradation, requires oxygen. Once the plastic cap is in place it will eliminate the percolation of rain water, which is the source of oxygen.

Our consultants advise us that there is no way to guarantee there will be no damage to a plastic over due to dffferential settlement. Preloading, as mentioned above, will minimize the possibility of subsidence - caused damage.

The answer is, that if damage to the cover does occur, there should be a method of locating the damage so that it can be repaired. The method that has been proposed, to determine if there is damage and how to locate it, is as follows:

Any ·substantive increase of contamination in samples from down gradient ·monitoring wells will indicate a poafl.ible break in the plastic cover. The first thing that would be dane ~d be to survey the bench marks on the landfill surface to see if ~e~ been a localized subsidence. If there has been a subsidenc~, ~ ~~• shut off the landfill venting system and pinpoint ~ny platic ~ver ~~ by checking the soil gas above the cover in the area Df .mbsideDce. Any break in the cover will allow land fill contaminaut ~~ in~ ±be soil layer above the cover. Analyzing the soil gas above ~ ~ ~ill allow any break to be located.

If .. no . az:ea .of .suhs.ideJ~~~:>e is derteectei! tlfuen soil gas checks (on a grid system) will be done over the £ntire landfill until the break is found.

Once a break is found, it wlll &e ea~ ~Q remove the two feet of soil and repair the break.

3) question - One attendee at t~ August 14, 1989 meeting said that they had read several articles which said that solJ~ification of organic waste did not work.

Answer - Grace investigated a number of different processes used to solidify waste. These various processes are classified into three major categories:

1) non chemical systems 2) inorganic systems 3) organic systems

Samples of the Acton site waste material were sent to various companies to test the effectiveness of the various solidification processes. Some thought they could successfully solidify the waste but others were not successful.

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The company that showed the most promise from the results of their laboratory tests was the Valley Forge Laboratory Corp. of Malvern, PA. To test out the process under actual field conditions it was decided to conduct the full process on a small scale but using equipment and batch sizes comparable to full scale operation. During this pilot operation sufficient waste, from the various waste sites in Acton, was solidified to form a pad 40 ft X 80 ft X 4 ft thick.

It was felt that the only sure way to determine if this process would be successful would be to pilot it on a full scale basis using actual wastes at the site. The piloting work did prove that the VFL process was successful. A detailed description of the VFL pilot project is given in Appendix E of the Phase IV report.

4) Question

An attendee at the August 14, 1989 meeting said they had read articles saying that 60 mm HDPE (high density polyethylene) was not a dependable cap material. They wanted to know how long it would last.

Answer

All types of capping materials were evaluated. A detailed description of this is covered in Section 5.2.1 of the Phase IV reports.

Briefly, this says that a synthetic membrane barrier was recommended rather than a clay cover, because in the free draining sandy soil in the Acton site, clay covers would have a tendancy to dry out and crack.

Of the six different synthetic membranes evaluated, HDPE was best from a standpoint of chemical resistance, tensile strength and tear resistance.

No one knows if the material will last indefinately because none has been in use for this purpose for that long. The reason why biodegradable plastics are being developed is because this type of polyethylene seems to last indefinately when put in town landfills.

If the cover material should fail it would be repaired or replaced.

General questions

Question

1) The question asked most often was "what would happen after 30 years" and what are the potential hazards under the worst conditions.

Answer

The best answer to the above questions is that even under a "worst case" scenario of everything going wrong, there would be no significant hazards to health or the environment.

Even if the landfill cover should eventually disintegrate and was not replaced, the biodegradable contaminants in a plume from the landfill would continue to biodegrade and not impact the environment. Any persistant conaminants (chlorinates solvents) would be at no greater level than they are today, and repeated analyses have shown that they do not adversly impact the Assabet River.

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In addition to the above there will be the following safeguards.

a) The EPA, under the Superfund statute, is required to reassess the potential hazards at the site every five years until it is delisted from the NPL (National Priority List).

b) Grace cannot sell any part of the site without notifying the EPA. "No conveyance of title, easement, or other interest in the property shall be conaumaoted by Grace, or subesequesnt holders of any interest in tbe property without complete provision for the fullfillaent of all requiTements of the decree". This is covered in part XVI of the Consent Decree which is binding on both Grace and EPA.

c) Part XV of the Consent Decree also requires that a notice of and a copy of the decree be filed for recording with the Middlesex South Registry of Deeds and/or the Massachusetts Land Court, as appropriate.

d) Section II of the Consent Decree makes it binding upon "the parties, their officers, employees, agents, successors and assigns, and upon all persons, firms, subsidiaries and corporations acting under, through or for, or in active concert or participation with, the parties who receive actual notice of this decree".

Question

2) Why isn't incineration a good way to go?

Answer

Most of the reasons for not electing the incineration alternatives were given by the EPA on the night of August 14, 1989. These include the following:

Off Site Incineration

a) Because of the limited amount of off site incineration capacity which will be available for the foreseeable future the best estimate is that it would take 10 years to dig up, transport and incinerate the waste material at the Grace Acton site.

b) The potential of hazard to health and the environment is far greater if the waste materials are dug up, prepared for shipment and during shipment, compared to covering on site. Since this would stretch over a 10 year period, the probability of accidents is even greater.

c) Since off-site disposal is merely transferring the possible hazards involved from one place to another and increasing the potential for added risk during transportation, off site disposal is not a favored alternative.

d) Transport of all waste off site would take about 5000 truck loads or 500 to 700 rail cars. Either way these would travel through the town of Acton with some probability of accident.

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.­e) The cost of offsite incineration is extremely high and is not justified

by commensurate benefits. The reason why the cost is so high and so much higher than on-site incineration is caused by the cost of transporting and the very high cost of preparing the waste for transportation and off site incineration.

On Site Incineration

a) On site incineration would take about seven years to complete. During that time, there would be an ongoing risk of operational upsets.

Because of the high temperatures at which incinerators operate, the narrow limits of safe operation and the need for continuous supervision, the chances of upsets in the process over such a long period of time is relatively high. Operational upsets due to variations in waste quantity, combustion temperature, control of excess air, etc., could pose significant risks to human health and the environment.

b) Excavating and preparing the waste for incineration, particularly from the landfill, would unduly increase the hazards to health and the environment, both on-site and off-site.

c) As can be seen from the Risk Analysis part of the Phase IV Report the risk to residents is essentially the same for the proposed Alternate II closure as for either the on-site or off-site incineration alternatives.

<J d) The cost of on-site incineration is also very high, which is notd;ti?lt;J·~~it·· J.P. Murphy, Jr. 17 Assistant Vice President

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Attachment

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COPIES TO:•

Sierra Club c/o Mr. Gil Woolle~ Newton, MA

Barry P. Fogel, DEQE, Worcester

William Cheeseman, Foley, Hoag & Eliot, Boston

~ · . . . Boward I. Fox, Sierra Club, Washington, DC

Donald Johnson, Town of Acton

Nigel Palmer, W.R. Grace, New York

Rosanne M. Joyce, Grace, Lexington

Richard Boynton, US EPA, Boston

Merrill S. Bohman, US EPA, Boston

Steven Anderson, Attorney, Boston

John MacLeod, Acton Water District

Doug Halley, Board of Health, Acton

() Robert Kimball, DEQE, Worcester

Russ Wilkie, W.R. Grace, Lexington

Mark Stoler, W.R. Grace, Cambridge

Acton Citizens for Environmental Safety c/o Charlotte Sagoff, Acton, MA