·. James F. Murphy, Jr. Assistant Vice President Polyfibron Division

GRACE W. R. Groce &Co. SS Hoyden Avenue lexington, Moss. 02173

(617)861-6600

May 28, 1986

Mr. Ira w. Leighton, Chief W&ste Management Division MA Superfund Section J. P. Kennedy Federal Building Room 1907 Boston, Massachusetts 02203

Mr. Gilbert T. Joly Regional Environmental Eng. Department of Environmental QualityEnstneertng Commonwealth of Massachusetts Central Reston 75 Grove Street Worcester, Massachusetts 01605

c::> Dear Messra. Letshton and Joly:

The first three comaenta of the sovernaent parties' ltat of ten comments attached to the letter dated March 27, 1986, were taken care of in Grace's Fourth Quarterly Report on the Aquifer Restoration Prograa in April, 1986. The answers to the other aeven comments are attached. If there ·are anyquestiona, please contact either Gary Siegel or ...

JPM. JR/pmp/19

1----"-·--··-.• ·--- ... . - ~.. ... _.~ ....___,__ ______

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RESPONSES TO JOINT EPA/DEQE COMMENTS ON THIRD QUARTERLY REPORT

Comment #4 (Concerning Tower Efficiency and Sampling eycle)

The natural occurence of ferrous (dissolved) iron, at elevated levels, in theground water, and the fact that this iron changes to the ferric (undissolved)state in the stripping tower, has caused cleaning problems in the strippingtower. The ferric iron deposits on the tower packing eventually starts theformation of iron bacteria, which obatruct the air passages in the towerpacking. This reduces the efficiency of the tower. Despite impairedefficiency, discharge of volatile organics to Sinking Pond, as measured at theinlet to the ~ have been insignificant. The reason for this is that theeffluent from ~ stripping tower gets additional aeration from naturalcascading on tie way to the entrance to Sinking Pond.

Since it becaaa evident that cleaning of the tower would be a problem, Camp,Dresser & McKee ha.e done pilo~ studies on the best method to clean the towerpacking using ...toua materials. Tfiia was described in the July, 1985Quarterly RepoKt for the Aquifer Restoration Program.

A method of C~DI the packing by recirculating a dilute solution ofhydrogen peroxi~R •• devised by CDM and PMC Corp. The tower was cleaned bythis method fl.. tt.ea at varying time intervals starting in October, 1985.It became in~tacly apparent that this rinsing technique was not going tobe thorough ~ for continuing maintenance.

() It was dete~ that the rinsing technique was cleaning the top of thesaddle packiDia '-t was not reaching the build-up on the bottom of thesaddles. To ._ t'borougbly clean the packing, CDM devised a procedure offilling the ~r wdth a dilute solution of hydrogen peroxide and soaking thepacking, the~ reaching the collected iron bacteria under the saddles aswell as on t~ 11ds method of cleaning was tried on May 12, 1986, but thepacking had ~ too severely coated with iron bacteria. Gas formation inthe hydrogen~de solution could not be vented through the pluggedpacking, and .~ SO cubic feet of packing was pushed out of the top of thetower. No f.u1du cleaning was attempted. The tower was put back inoperation on ale: -.uer Restoration System and· subsequent analysis showed anefficiency tif WL

Present pla'IRI- to replace the existing packing with new packing. 'lbis willtake about oneeel. to implement and will be done about the middle of June.Soak cleaning ~1 be done at the end of two months operation. CDM A

anticipates no:po.lems with venting of gas during cleaning since the packingwill be relati~it clean and the hydrogen peroxide will be pumped in at thetop of the ~~-c column rather than the bottom. 'lbrough this means weplan to eat~· the optimum cleaning cycle.

Until tht.· • ...-.u complete we will be testing .. the influent and effluent ofthe stri~g~ weekly to check efficiency.

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Page 2

Comment 15 (Concerning the Port Pond Brook Sampling)

The attached letter written by Edward B. Fitzpatrick of CDH to James P.Murphy, Jr., of W. R. Grace, on May 6, 1986, covers the Grace position onfield investigation in the~wabrook/Port Pond Brook area.

Comment #6 (Concerning the Containment Area and Certain iell Pumping Rates) The Battery Separator Chip Pile, which liea entirely to the south of therailroad, liea eo.pletely within the containaent area. The North Lagoon doealie outside of tbe containaent area, however, there ia no evidence that it ianow a aignificaat leachate source. Thia can beat be aeen by recent analyaeaof all levels of ARB. These analyses ahow contamination to be below thedetection level ~f 10 ppb.

The ILP well is throttled back t~ !ta present pumping rate to prevent frequenttripping of the low flow cutout switch. Soil foraationa at that location weretighter than autfcipated.

The WRG-3 well Ia& been pumping at the maximum rate of the exiating well pump.Tbe rate appears to have fallen somewhat starting in the fall of 1985 whichcould indicate dat the well needs to be cleaned.

The Southern ~ W811 baa been throttled to keep the Agway Landfill out ofthe containmen~ area. The ELF Well vaa at about deaign rate (29 GPM) in,_) Noveaber and ~r of 1985. It will be returned to that rate.

Comment #7 (Qmcerning Detection Limite)

On all future .atlle organic analyaea, Grace will uae a dete.ction limit of 1ppb.

Co~~~~~~ent #8 Cencerning Residual Contamination in the Masa Broken Stoneat Area

The return of ~ from the aquifer restoration wells and WRG3 well toSinking Pond cauaean increased flow through the aquifer in the Haas BrokenStone Pit area. ~- of course produces an acceleration of the aquifercleansing in thia&rea.

It waa antici~ ' that additional flow would be realized from this areatoward the W.W ao Landfill Well and the Southern Lagoon Well. The S. L. w.pump is run~at a reduced rate and the W. L. P. Well is not operating atall at the ~;..t of the state, in order to prevent drawing contaminationfrom the Agww amdflll.

Grace feelat~theae facilities provide sufficient unutilized back-up forimproving the -~toration of Mass Broken Stone Pit.

Page 3 (

Comment #9 (Concerning Residual Contamination near the Auabet Well Field)

~ c~r.t~ination at depth in the immediate vicinity of the Aasabet vella ia being addressed by the groundwater recovery system. Continued pumpins of RP-1 is preventing the migration of additional contaminants from the north and is also treating the residual contamination to the east. We are nov inveatigating the possible effects of low ground water table, low water levela in Muskrat and Turtle Ponds, and recent data concerning operatins practice at Aaaabet 1 and 2 on cleaning up the .Usabet Well Field. Appropriate action will be taken pending results of the investigation.

Comment #10 (various items)

The first parasraph is concerned with the impact of iron on Sinking Pond. This was thoroushly discussed in several letters. One was a June 13, 1985 letter from Ja~t Johnson of CDK to James r. Murphy, Jr., Which vas sent to Thomas c. HeHabon under a cover letter written by Jaaes r. Murphy, Jr. on June 13, 1985. Copies were sent, among others, to Kenneth E. Wenger of the EPA and Edmond G. Benoit of the DEQE. The other letter vas one written by Gary Siesel to Thomas c. lldfahon on May 8, 1985. Distribution vas the sa• as the first letter.

Essentially tbeae two letters point out the various reasons why Grace feels that iron does not have a detrimental impact on Sinking Pond.

The last part of Comment #10 is concerned with contamination in the Lavabrook/Fort fond Brook area. Grace's position on this vas siven to the answer to Co.-et 15.

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CD CAMP DRESSER & McKEE INC.

_1011_,.,........,.......,.,., MAY 81986 One Clflter Plea

,...,_._,_....,._,~. lolt011. MIUKII-* 02101 117 ,.,-1151

May 6, 1986

Mr. James F. MurphyAssistant Vice President Polyfibron Division W.R. Grace I Co. 55 Hayden Avenue Lexington, MA 02173

Recommended Approach to Lawsbrook/Scribner Wellfield and Fort Pond Brook Issue

Dear Mr. Murp~:

We have considered the issues involved in addressing the undocumented but alleged (by the Water District or their representatives) contamination byGrace of the Lawsbrook and Scribner Wellfield. We reco..end an approach to identify the magnitude and source of the probleM in this letter.

The most important first step is to obtain all data fro. the Lawsbrook,Scribner and Christofferson Wellffelds which ~as been collected by the Water District to date. Relevant data includes production and .anitoringwell locations, depths, completion data, pumping records, and analyticalresults (particularly for volatile organics). This includes any new monitoring wells installed in connection with recent studies. We cannot overemphasize the importance of these data in allowing us both to define the magnitude of any problem which might exist and to p~ an any additional data collection in an efficient, timely Manner. We think that this is a reasonable request to make considering that all data collected by Grace since the inception of the Acton Environmental Program has been made available to the Water District.

If the data obtained from the Water District show that volatile organiccontamination 1s coming frot11 the southern direcdon, we would then recommend that all existing production and monitoring wells in the area be resampled. If the new data support the data of record, then we would recommend that a new multi-level monitoring well be installed south of the wellfields in the vicinity of Lawsbrook Road. Further action, leadingtoward tracking the plume to its source, would depend on the results of all of the proposed testing.

CAMP DRESSER & McKEE INC.

Mr. Ja es F. Murphy May 6, 1986 Page Two

In parallel with the above progr•, we rec01111end that we locate the north plu.e by sa~ling groundwater, surface water and stre•bed soil at existingFort Pond Brook sa•pling station locations FP-1 through FP-6 and at a new location, FP-7, near Lawsbrook Road.

In sUB~ary our recommended approach consists of the following:

Take appropriate steps to obtain monitoring and production well construction information, operating records and all data collected bythe Water District at the Lawsbrook and Scribner Wellfield.

Res.-ple all production and .anitoring wells at the wellfield to verify and supple~ent data obtained from the Water District.

If necessa~. install and sample a new multilevel well between the Wellfield and the Grace Site in the vicinity of Lawsbrook Road.

Sample surface water, groundwater and streambed soils at the existingand new sa•pling stations FP-1 through FP-7 in Fort Pond Brook.

We re~ain available to discuss our recommendations at your convenience.

Ye~ Truly Yours,

CAMP, DRESSER I McKEE INC.

~ a.Lz:::. ,_ Edward B. Fitzpatrfc~ -- - - ~ Associate

GENERAL ~!AILING LISTING

Mr. Gilbert T. Joly The Commonwealth of lwssachusetts Department of Environmental

Quality Engineering Central Region 75 Grove Street Worceater, !lA 01605

Mr. Ira W. Leighton, Chief Waste Management Division KA Superfund Section J. F. Kennedy Federal Building Room 1907 Boston, KA 02203

James F. Murphy, Jr. Grace - Lexington

Mr. Howard I. Fox Sierra Club Legal Defense Fund ·U16 l' Street• . N.W., Suite 300 Washington~ D.c. · 20005

0. Mario Favorite Grace - Cambridge

Gary w. Siegel Grace - Lexington

Edward B. Fitzpatrick, Associate Camp, Dresser &McKee, Inc. Industrial Engineering Division One Center Plaza Boston, KA 02108

Mr. Kenneth E. Wenger Environmental Engineer Compliance Branch u.s. Environmental Protection Agency Region 1 J.F. Kennedy Federal Building Room 1903 Boston, KA 02203

Mr. Bernard J. Murphy, Jr. Town Manager Town of Acton 472 Main Street Acton, MA 01720

Mr. John MacLeod Acton Water District P.O. Box 953 693 Massachusetts Avenue West Acton, !lA 01720

Mr. John E. Ayres Goldberg, Zoino &Associates, Inc. 30 Tower Road Newton, KA 02164

Mr. Steven Anderson Palmer &Dodge One Beacon Street Boston, KA 02108

Mr. Williaa J. Cheeseman, Esquire Foley, Hoag &Eliot One Poat Office Square 19th Floor Boston, KA 02109

Mark Stoler Grace - Cambridge

Nigel I. Palmer Grace - New York

Chron File

Acton File

William H. Starr Grace - Lexington