DVMAMAC f\ iff"CORPORATION AJ gj v

Public Ledger BuildingIndependence Square .6th and Chestnut StreetsSuite 872 . -Philadelphia, PA 19106

Environmental Services

Telephone: 215-440-7340Fax: 215-440-7346

February 10, 1992

Mr. Randy SturgeonU.S. Environmental Protection AgencyRegion HI841 Chestnut BuildingPhiladelphia, PA 19107

Reference: Contract No. 68-W9-0005Work Assignment No. C03034DuPont - Newport Site

Subject: Feasibility Study Report Review

Dear Mr. Sturgeon:

In accordance with Task 3 of the work plan for the abovereferenced work assignment,Dynamac is submitting two copies of the revised letter report containing technical reviewcomments on the draft feasibility study report, as well as a magnetic copy.

The draft feasibility study report is entitled "Focused Feasibility Study, duPont - NewportSite, Newport, Delaware". This report was prepared by Woodward-Clyde Consultants andis dated December 23, 1991.

The objective of the review of the feasibility study report is to determine if the reportprovides sufficient information for the development, screening, and detailed analysis ofalternatives, that is, if the report follows applicable guidance.

The following documents were used as reference for the review:

• GuidanclTfor Conducting Remedial Investigations and Feasibility Studies underCERCLA; EPA 540/G-89/004; October 1988 (the guidance document)

• Administrative Order By Consent; July 22, 1988<

• National Oil and Hazardous Substances Pollution Contingency Plan; 40 CFR 300(the NCP); July 1, 1990

Corporate Headquarters: The Dynamac Building, 2275 Research Boulevard, Suite 500, Rockville, MD 20850-3268

Work Assignment No: C03034February 10, 1992

Page2

Attachment 1 contains general comments on the feasibility study report while Attachment 2contains specific comments on the report. Attachment 3 is a summary of the commentspresented in Attachments 1 and 2. Attachment 4 is an article describing an innovativetechnology to treat contaminated soils/groundwater that will not require excavation.

In general, the report does not appear to be consistent with the NCP and the guidance document.Deficiencies were noted during the review in the amount of information provided in the reportand in the quality of information provided. Therefore, it is highly recommended that thecomments presented herein be incorporated into the report. In Dynamac's opinion, the reportrequires revision and resubmittal.

Dynamac is prepared to attend a review meeting with EPA to discuss the reviewed documentsand the overall conclusions expressed in the report Dynamac will arrange this meeting atEPA's convenience, when requested.

If questions arise concerning this report, please contact Dynamac Corporation at (215) 889-3900.

Sincerely,DYNAMAC/CORPORA1TON

Camille Costa, P.E.Engineering Manager

CC:mm

Attachments

cc: Ms. Donna McGowan, USEPA Region m RPOMr. Robert Stecik, Dynamac, Philadelphia Operations

Attachment 1General Comments

Comment No. 1

The Executive Summary fails to discuss the full extent of the impact of the Site on thesurrounding environment. The results of the Draft Environmental Evaluation, such as it is,are only cursorily mentioned. Furthermore, there are serious inadequacies in the DraftEnvironmental Evaluation. For these reasons revise the Executive Summary once theimpacts of the Site on the surrounding environment have been adequately determined.

Comment No. 2

The NCP states "Development of alternatives shall be fully integrated with the sitecharacterization activities of the remedial investigation described in paragraph (d) of thissection" (40 CFR 300.430(e)(l)). Explain each of these activities in the feasibility studyreport in light of its applicability to the Site. Address, all the activities in order to providean overall view of Site conditions not currently presented in the report.

Comment No. 3

The development of alternatives as presented in the feasibility study does not seem to followthe sequencing outlined hi the NCP (40 CFR 300.430 (e)(2 through 6)). Alternatives couldnot be found that recycle waste. Remedial goals establishing exposure levels that areprotective of human health and the environment could not be found. Innovativetechnologies were not mentioned. Source control actions do not concertedly considerreduction of toxicity, mobility, or volume and elimination or minimization of long-termmanagement. Develop such remedial goals; include innovative technologies; providealternatives that reduce toxicity, mobility, and volume and that eliminate or minimize long-term management

Comment No. 4

Based on the present contents of the feasibility study, it appears that the alternativesselected do not meet 40 CFR 300.430 (e)(9)(iii)(A). This section of the NCP refers toassessment of alternatives "...to determine whether they can adequately protect humanhealth and the environment...". Assess each alternative on the basis of effective mitigation,and minimization of threat to and provision of adequate protection of public health andwelfare and the environment.

Comment No. 5

Because of the content of the feasibility study, in particular because of the lack ofdocumentation and of enumeration of contaminant concentrations and ARARs/goals, anyclaim of technical impracticality does not seem to be substantiated. Refer to 40 CFR300.430 (e)(7)(ii), and substantiate technical impracticality.

Comment No. 6

A minor amount of remediation has been proposed to reduce the flow of contaminants intothe Christina River. No remediation has been proposed to treat the Ciba-Geigy/Holly Runareas of the Site, which contribute to river contamination via seeps and ground water.Consider remediation of these source areas in addition to remediation of migrationpathways to treat the River, the pathways, and the Ciba-Geigy/Holly Run areas.

Comment No. 7

Although vast areas of the Site may be contaminated beyond remediation using conventionalmethods, innovative technology can remediate soils/groundwater without disturbing buildingfoundations and contaminating lower groundwater zones; or placing workers at risk due toexcavation. One technique is presented in Attachment 4. Augment the technologiesconsidered for screening, in particular, include such innovative technologies.

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Attachment 2Specific Comments

Comment No. 1 Executive Summary, page ES-1, second paragraph

As noted in Section 2.2, other ARARs and TBCs besides those considered may apply.Reword this paragraph to reflect that other ARARs or TBCs may apply. The significanceof acknowledging the existence of other ARARs is the potential use of the ARARs in thedevelopment of remedial alternatives.

Comment No. 2 Executive Summary, page ES-1, third paragraph

Revise this paragraph to include information presented in the "Review of EcologicalConcerns", prepared by Dynamac and dated December 31,1991, and Sections 3.3 and 5.6.For example, identify the areas in which metal toxicity impacts are likely as well as otherimpacted areas.

Comment No. 3 Executive Summary, page ES-1, fourth paragraph

Add the Holly Run Plant Operations Area, the Christina River, and the underlyinggroundwater to the list.

Comment No. 4 Executive Summary, page ES-2, first full paragraph

Expand the range of technologies identified in the body of the report and mentioned hereto address not only groundwater and soils, but also sources, seeps, surface water, andsediments. Delete the second sentence of this paragraph or amend it as necessary basedon the expanded range of technologies considered.

Add the words "remedial goals" to the list presented in sentence three. No remedial goalscould be found in the feasibility study, although they are discussed in the guidancedocument.

Revise the fourth sentence to identify technologies retained after reconsideration ofalternatives.

Reword the fifth sentence, deleting the portion of the sentence after the comma, as a resultof the consideration of this AOI.

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Comment No. 5 Executive Summary, page ES-2, second full paragraph

Delete the word "remaining" from the first sentence, and add the words "remedial goals"after the word "ARARs".

Revise the bulleted items to reflect reconsideration of alternatives and add the Ciba-GeigyPlant Area, the Holly Run Plant Area, the underlying groundwater, and the Christina Riverto the list of bulleted items, along with the alternatives considered for these AOIs.

Comment No. 6 Executive Summary, page ES-2, third full paragraph

Modify the second sentence to read "...would address the remedial goals, identified risks...".

Comment No. 7 Section 1.5

The list of primary chemical constituents of concern that appears in this section (barium,cadmium, zinc, lead, PCE, TCE) is at least the fourth list of "constituents of concern","compounds of concern", "target parameters" or "parameters of concern" given in variousDuPont-Newport Site documents. The other three chemical lists and their respectivedocuments follow.

1) Environmental Evaluation (7/30/91): Barium, cadmium, chromium, copper, lead,mercury, zinc.

2) Human Health Evaluation (10/14/91): antimony, arsenic, barium, benzo(a)anthracene,beryllium, bis(2-ethylhexyl) phthalate, cadmium, carbon tetrachloride, 4-chloroaniline,chlorobenzene, chromium, cobalt, copper, 1,1-dichloroethylene, manganese, mercury, nickel,PCE, thallium, TCE, vanadium, vinyl chloride, zinc.

3) Remedial Investigation (11/1/91): arsenic, lead, copper, mercury, silver, antimony,selenium, vanadium, PAHs, PCE, TCE, barium, zinc, cadmium.

The nature and extent of contamination at the DuPont-Newport Site has not been clearlyexplained, and the multiple lists of chemicals of concern that have been submitted in thevarious remedial investigation documents and now in the feasibility study only add to theconfusion surrounding this issue. Nowhere in any of the documents submitted has thereappeared an explanation of why the chemicals of concern vary from document to document.

SR3I2308

Develop a list of the chemicals of concern at the DuPont-Newport Site that are to beaddressed in the feasibility study. Consider all of the abovelisted contaminants, and fpllowa practical, conventional, precedented, documented scientific approach in the developmentof the final list Amend the feasibility study to include both consideration of the possibleimpacts of all the final chemicals of concern and an analysis of remedial alternatives toameliorate those impacts.

Comment No. 8 Section 1.5.3, page 1-10, last paragraph (continuing to page 1-11)

Include in this paragraph a statement on the present location of the waste in the NorthDisposal Site. In addition, reword the last sentence of this paragraph to read "...wastes areconsidered a potential issue of concern...". While it may be true that no impacts of theThoria Dispersed Modified Nickel have been observed to date, the drums may leak in thefuture and impacts may be obsef ;i. Impact may be greater than that assessed in the DataSufficiency Memorandum since calculation presented ignores daughter products andsince the alpha-recoil theory doe. ot address chemical leaching via redox reactions.

Comment No, 9 Section 1.5.4, page 1-12, last paragraph

As discussed in the November 27,1991 meeting, a reference from the literature is requiredindicating that Phragmites australis does not proliferate in deep water.

Delete the portion of the last sentence of this paragraph beginning "...perhaps because of..."since this information may be conjecture.

Comment No. 10 Section 1.5.6

Mention the elevated levels of PAHs detected in this section.

Comment No. 11 Section 1.6, page 1-14, third bullet

Include the seeps along the Christina River (at both the North Disposal Site location andthe Ciba-GeigyJfocation) in the feasibility study as threats and potential areas to beremediated According to information previously presented (Data Sufficiency Report,Volumes 1 and 2), samples collected from seeps exceeded DNREC Surface Water QualityStandards and EPA Criteria for the Protection of Freshwater Life for several compoundssuch as aluminum, cadmium, copper, lead, and zinc.

AR3I2309.

Comment No. 12 Section 2.1, page 2-1, last paragraph (continuing to page 2-2)

Identify the nature of the ARARs listed in table 2-1 (i.e., Maximum Contaminant Levels)in the second sentence of this paragraph. Include gU the MCLs (or other ARARs/TBCs)in the table, along with the maximum concentration of each contaminant detected at theSite, and an indication of which concentrations exceed MCLs (or ARARs/TBCs).

Specifically list the "other ARARs" in both the table and the text.

Comment No. 13 Section 2.1, page 2-2, last paragraphi

Table 2-3. Combine this table with table 2-1 and expand the result to provide theinformation requested in Comment No. 12.

Table 2-4. Also list in this table jjl the pertinent ARARs/TBCs along with the maximumconcentration of each corresponding contaminant detected at the Site, and an indication ofwhich contaminants exceed the ARARs/TBCs. Include the seeps associated with the NorthDisposal Site location and the Ciba-Geigy location in this table.

The information requested in Comments No. 12 and 13 not only provides the reader abetter description of Site conditions, but also sets the stage for the development of remedialaction objectives, as outlined in the guidance document.

Comment No. 14 Section 2.1, page 2-3, top of page

The conclusion of this paragraph, i.e., "therefore the Threshold Value Guidelines are notconsidered to be applicable TBCs for this Site" is a direct contradiction of the DraftEnvironmental Evaluation for the DuPont-Newport Site submitted on July 30,1991. In thatdocument, (Section 5), the Threshold Value Guidelines are used as a critical factor in thechoice of the Site constituents of concern.

Such contradictions between documents submitted for the Newport Site, particularly withregard to the identification of chemicals of concern and evaluation of die extent of Site-related contamination, lead to the disconcerting conclusion that the impacts of the Site onthe surrounding environment have not been adequately evaluated to date. That is, theremarkable inconsistencies and ambiguities in the description of Site impacts appear to benot due to simple deficiencies in report-writing and communication skills but rather tofundamental scientific inadequacies in the design and execution of the remedialinvestigation.

\

Consider the Threshold Value Guidelines as applicable TBCs.

&R3123IO

-, '- ---«T.

Comment No. IS Section 2.2, page 2-4, first full paragraph

In keeping with the EPA comments on the draft RI report, delete the words "greatly over-estimated" and "very conservative". For more detail, refer to the comments contained in theDecember 16,1991 letter to Mr. Joel Karmazyn, E.I. duPont de Nemours & Company, fromMr. Randy Sturgeon, EPA.

Comment No. 16 Section 23, pages 2-4 and 2-5

This section requires revision in keeping with the report "Review of Ecological Concerns",prepared by Dynamac and dated December 31,1991, in particular, Section 6.3.

The feasibility study dismisses the Christina River as an area of consideration on the basisthat "...no consistent pattern of contamination has been identified." As noted elsewhere inthese comments and as discussed in the Review of Ecological Concerns, it is not clear thatthe failure to identify a consistent pattern of contamination in the near-Site Christina Riveris not a reflection of the scientific inadequacy of the data collected at the Newport Site.The surface water quality data presented (in the Draft Human Health Evaluation, DraftEnvironmental Evaluation, and Remedial Investigation) are not sufficient to support thedevelopment of any scientific conclusions regarding the extent of the impact of the Site onthe environmental quality of the river. However, in the Environmental Evaluation (page8-4), the Remedial Investigation (page 4-15) and in the Feasibility Study (page 2-4) it hasbeen acknowledged that Site constituents of concern are elevated in the near-Site portionsof the river. As concluded in Section 6.6 of the Review of Ecological Concerns, there areenough data to indicate that the Site is contributing metal concentrations to the ChristinaRiver above the degraded conditions associated with other non-Site sources locatedupstream.

It is recommended that a more comprehensive investigation of the impacts of the Site onthe river, including collection of surface water samples from locations along the length ofthe river near the Site, be conducted and that remedial alternatives to address these impactsbe included in a future draft of the feasibility study.

Comment No. 17 Section 2.3, page 2-5, first full paragraph on page

Given the paucity of analytical data collected at the South Disposal Site during the remedialinvestigation, (see Remedial Investigation report, or Environmental Evaluation), an analysisof remedial alternatives for this area is not yet appropriate. Adequate sampling and datainterpretation should be conducted for the South Disposal Site area, followed by an analysisof remedial options.

4 R 3 I 2 3 I f

Comment No. 18 Section 2.4, general comment

Revise this section to include remedial action objectives and general response actions asdiscussed in the guidance document. Identify Preliminary Remediation Goals, that is,specific numerical concentrations and cite the references from which they are taken. Someof the "Remedial Goals" listed seem to be response actions instead and require revision.The following do not appear to be addressed in the table: seeps near the North DisposalSite and Ciba-Geigy Area; the potential for the future release of thorium to theenvironment; surface soils in the Ciba-Giegy Area; industrial exposure to lead; sedimentsin the South Disposal Site. Address these in the table. An important consideration may bethe route/receptor relationship; gaining an overall picture of contaminant migration priorto considering routes/receptors when selecting alternatives. Include the Christina River asan Area Of Interest, as discussed in the "Review of Ecological Concerns", prepared byDynamac and dated December 31, 1991, Sections 6.3 and 6.6.

Also in keeping with the guidance document, include approximate volumes of contaminatedmedia in this section, for use during remedial action screening and development.

Comment No. 19 Page 2-6, last paragraph

Judge the quality of the Christina River also by the surface water sampling conducted inAugust, 1987. The water was above ARARs in cadmium (Acute Freshwater Aquatic Life)and lead (Chronic Freshwater Aquatic Life). Since cadmium and lead are prevalent in Sitesoils and in the groundwater seeps flowing into the River, the Site remains a probablesource. Any diligent and carefully planned remediation on-Site may eventually reduce levelsof contaminants in the river.

Comment No. 20 Page 2-6, last paragraph

In reference to the end of the first sentence, ..."No consistent pattern of contamination hasbeen identified..." in the Christina River because no consistent surface water samplingprogram has been initiated. Information from only one sampling date is available, asdiscussed in the general comments, and this data is from just one location.

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'" ~ -

rnmment No. 2.1 Section 3.0, general comment

The development and screening of alternatives, as presented in text form, does not appearto consider the wide range of alternatives presented for consideration in the guidancedocument Expand this section to include a greater range of alternatives, and include thesealternatives in the visual (i.e., table) format as well as in text. The alternatives consideredseem to dismiss too easily many actions. The NCP ideas of reducing exposure, preservingresources, and restoring resources do not appear to be carried through. Give more seriousconsideration when retaining or eliminating actions.

Rationale for eliminating alternatives do not seem to be well documented, as called for inthe NCP. This.applies particularly to section 3.1.3. Augment the documentation by makingit more thorough, in particular provide documentation for the following portions of section3.1.3:

• Page 3-4, paragraph two

• Page 3-4, paragraph three, continuing to page 3-5

• Page 3-4, first full paragraph, bullet three

• Page 3-4, second full paragraph (last paragraph of section 3.1.3)

Comment No. 22 Section 3.1.1, page 3-3, first full paragraph

It is claimed that fill contamination will render groundwater remediation impossible. Thisstatement is not always true even for conventional recovery techniques, but is dependentupon the state of contamination within the fill zone. Also, pumping groundwater does nothave to contaminate the deep water bearing units, as is claimed in the last sentence.Vertical migration of water (and contaminant) may depend on pump depth. A recoverypump could be placed as deep as the lowest zone of contamination but not in a lowerformation, as in some wells constructed at the Dupont-Newport Site. Careful placement ofthe pump may prevent contamination from flowing downward into the lower, cleaneraquifers.

"•fc HPAn innovativejmethod to treat volatiles, semivolatiles, and inorganics in groundwater (andvolatiles with some lighter semivolatiles in soils) is the Dual Vacuum Extraction technique.This technique, as described in the article presented in Attachment 4 (Hazmat World, 1991),uses vacuum extraction within water recovery wells to air strip the vadose zone along withthe aquifer above the pumping cone of depression. On-Site these areas would correspondto the Fill layer and the Columbia Formation, respectively. Multiple extraction wells mightaddress problems with obstacles due to aquitards. x

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Air stripping occurs concurrently with the pumping of groundwater; groundwater would betreated separately from the extracted air. The recovered groundwater can be remediatedusing any technology available. The mobile organics in the Fill layer would eventually bevolatilized by air, but to treat metals the soils might have to be flushed out, or eventuallysealed through capping.

Excavation of Fill soils, especially where lead exceeds the 1000 ppm action level, alwaysremains an option. Based on chemical data, removal may not need to approach the depthof the groundwater table. In the five borings with lead in soil samples exceeding 1000 ppm,the average depth of the extent of contamination is 6 feet. The maximum is 10 feet deepat B-8 which is 5 feet above the water table there. Also, if the area around the five boringswas excavated to an average depth of 6 feet, then the total volume of soil removed wouldapproach 20,000 cubic yards. This number is far less than the 80,000 cubic yards quoted andconsidering the paved areas on-Site, the final removed volume could be less than what isnow proposed.

Comment No. 23 Section 3.1.3, Page 3-4, last paragraph

The previous pumping of supply wells WW-11 and WW-13 cannot be proven responsible forthe vertical downward migration of contaminants without the provision of detailed well logs,pumping records, chemical results and/or pump test data. In the absence of thisinformation, delete reference to the supply wells, or provide this information.

The mere history of supply well use does not discount the feasibility of groundwaterwithdrawal technologies, especially since the wells may not be responsible for contaminationin the lower aquifers.

Comment No. 24 Section 4.0

The discussion presented does not appear to address 40 CFR 300.430 (e)(9)(iii)(C)(l) or40 CFR 300.430 (f)(ii)(E). The referenced section (e) may particularly be applicable interms of "...residual risk remaining from untreated waste...". The referenced section (f)presents the potentially applicable (due to the high concentrations of metals detected)concept of resource recovery. Address both of these.

After additional alternatives are considered in section 3.0, revise section 4.0. This appliesin reference to Comment No. 21 and also in reference to the report "Review of EcologicalConcerns" prepared by Dynamac and dated December 31, 1991.

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Comment No. 25 Section 5.0, first bullet

It may be premature to request a waiver, given the limited number of alternativesconsidered. Consider a wider range of alternatives, such as dual vacuum extraction, in aneffort to meet the intent of the NCP. Attachment 4 contains information about thistechnology.

Comment No. 26 Section 5.0, second bullet

It may be inappropriate to lump these two areas in one conclusion, since they do havedifferent characteristics. As it may be possible to implement some source control,investigate additional alternatives to do so. Controlling the sources of contamination mayalleviate or eliminate routes and receptors and may beneficially impact other areas requiringremediation.

Cfomment No. 27 Section 5.0, third bullet

Consult Sections 6.3 and 6.6 of the report "Review of Ecological Concerns", prepared byDynamac and dated December 31, 1991, revise this comment accordingly. As indicated inComment No. 16, while data is not sufficient to support the development of conclusionsregarding the extent of impact of the Site on the River, data exists to identify the Site as acontributor of at least metals to the River. Identify the Site as such and propose in the textpresenting and discussing remedial goals/alternatives, ways to delineate areas to beremediated and actions to be considered for remediation. Revise this bullet to define theremedial alternative selected.

Comment No. 28 Section 5.0, fourth bullet

Clarify the first sentence of this conclusion, since surface soil (that is, the 0- to 2-feetinterval) was not analyzed except for B-25.

Comment No. 291 Section 5.0, page 5-2, first bullet

The wetlands and the seeps do not appear to be addressed by this conclusion. Change thisconclusion after consideration of Sections 4.0 and 5.0 of the report "Review of EcologicalConcerns" prepared by Dynamac and dated December 31, 1991, and a greater initialnumber of alternatives. Revise this comment to define the selected alternative.Demonstrate clearly how the selected alternative meets the goal of source control for theDisposal Site itself, taking into account the drums of Thoria Dispersed Modified Nickel.

./IR3I2-3I5

Comment No. 30 Section 5.0, page 5-2, second bullet

Change this conclusion after consideration of Sections 4.0 and 5.0 of the abovereferencedreport and a greater initial number of alternatives. Clarify the correlation between theSouth Disposal Site, stressed vegetation, and toxic metal concentrations. Assess the impactof these concentrations, present and discuss remedial goals/alternatives, delineate areas tobe remediated. Revise this comment to define the selected alternative.

Attachment 3Summary

Major deficiencies in the feasibility study report appear to arise from inconsistency with theNCP and the guidance document In particular, many of the topics discussed and logicalarguments presented do not seem to follow 40 CFR 300.430, and Chapters 4 and 6 of theguidance document.

Dynamac recommends the feasibility study be revised to at least include a better descriptionof Site conditions (topography, routes, receptors), a definitive comparison of Sitecontaminants and ARARs (for all contaminants detected, not just for chemicals of concern),a list of remedial action objectives and general response actions, a more detailed list ofalternatives considered for screening and development (including seeps, sources, sediments,and the Christina River), and a more comprehensive documentation of alternatives rejected.

ATTACHMENT 4

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•~-" : L **-&*- • - «r-7'- -_-ip

Dual vacuum extraction sinks below the surfacein groundwater cleanup

By Kimfaeriy A. Roy

Remediating groundwater using sama, with some additional water- and treat systems will not clean upconventional pump and treat sys- handling components. OVE systems sites contaminated with dense non-

terns can take decades, centuries or contain a pump or similar mechanism aqueous phase liquids (DNAPL) in ourlonger. While conventional wisdom that withdraws groundwater under lifetime. However, DVE will dean it uptells us patience is a virtue, it also can vacuum via the extraction wells. in a very short time.'o* costly and unnecessary. One of a Extracting water lowers the water OVE is applicable to volatiles andnew generation of groundwater dean- table, thereby expanding, or deepen- semivolatiles amenable to vacuumup techniques, dual vacuum extraction ing, the vadose zone, Malot explains. extraction. For example, neither tech-(QVE) takes into account contaminant This action, he continues, increases nique can handle heavy, chlorinatedmovement through the subsurface, as the effectiveness of the vacuum ex- compounds or hydrocarbons heavierwell as hydrogeologic conditions, to traction by exposing residual contam- than the mid-diesei range, Malot says.provide relatively quick, efficient inants that typically collect under the Basically, they will not recover pesti-deartup. static water table. cides, such compounds as dioxin or

DVE is based on vacuum axtrac- .At sites containing such contami- PCSs, such heavy organtcs as fuei oilton, a soil remediation technique used nants as petroleum hydrocarbons, No. S, or metals, with the possible ex-for removing VOCs and semivoiatiles which are lighter than water, a mass of ception of mercury, he says. However.in the vadose, or unsaturated, zone. floating hydrocarbons or residual liquid he adds. It is one of the most effectiveOVE takes the technique one step contaminants collects between the ways to dean up soS and groundwaterfurther, allowing simultaneous soil and unsaturated and saturated zones, contaminated with VOCi.*groundwater deanup. Both techniques Malot explains. This mass "tends to In th* field. At one site, a pumpwere developed by Terra Vac Presi- spread out laterally into a pancake- and treat system had -been operatingdent Jim Malot and Meivin Visssr, an shape configuration,* which Malot for "quite some time" with no effect onengineer with UpJohn Co. (Kala- refers to as the mobile, liquid-phase trie contaminant concentration, Maictmazoo. Mien.). The two began devel- plume. As the water table fluctuates relates. Once installed. OVS >oping the concept in 1982 in response naturally, the liquid-phase plume, or contaminant recovery by sixfol|to a sit* owned by UpJohn in Puerto 'pancake,* moves up and dawn, within 3Va years the cancerRico, where USTs leaking carbon leaving immobile residual hydro- reached a drinking water :tetrachloride contaminated about 1 carbons behind in a voluminous ppb in nearly all of the wells, he can-million cubic yards of soil. Today, 'smear* zone, he continues. (The dudes.Malot owns exclusive rights to the smear zone; he adds, can be 10 times In another instance, a gasolinetechnologies, including two process thicker than the floating hydrocar- fueling station had initial soft cancan-patents. Besides Terra Vac (Puerto bans.) The residual acts as a signifi- trations of total petroleum hydro-Rico), licensees of the technologies cant source of dissolved contamination carbons (TPH) as high as 2.000 ppm.include CH,M Hill (Engtewood. Goto.), by continuing to dissolve into the and floating liquid-phase hydrocarbonsDOE' s Savannah River Plant site grourtdwater over a period of many measured 3 feet in the well. After 23(Aiken, S.C.) and Canonic Environ* years, he concludes. weeks of operations, benzene concan-mentai Services Corp. (Porter, ind.}. OVE. however, kilts the sourca of trations in the soil were all below 0.1Vacuum extraction. A basic vac- contamination while simultaneously ppm, and 71 percent of the sail sam-

uum extraction system contains three deaning groundwater and exposing pies were non-detectable. On* hun-components — vacuum equipment. the residual smear zone to vacuum dred percent of the groundwaterwhicn is th* driving fore* behind th* extraction. With conventional pump samples also showed non-detectableprocess, on* or mor* w*«s installed in and treat systems, one pump lowers b«nztn* levels. Matat concedes.the treatment zon*. and a vapor treat- th* water table, expanding the im- Although OVE is suitable for allmem technique. (HW. 'Technology,* mobfl* smear zone near th* extraction sites wnere vacuum extraction isOctober). QVjt" operates th* same w*tt. wh*r» small amounts of mobH* applicable, th* deeper th* contami-way, except extraction welts are hydrocarbons ar* skimmed off by a nation, th* more comptex th* solution.ptacad betow th* wawr tab<*, secondary pump. However, Malot b*eom*s." Makn says. *t imagin* th*r*

A vacuum system inducas air flow notes, this setup creates a con* of ar* some practical limitations, for ex-through the vadosa zone and induces depression that can spread the smear ampi*. in some very permeable aqut*volatilization of VOCs from the soil into zon* and sht*Jd som* of th* immobile fers. but we havent s*»n any (sites)th* air stream. Water usually is residual hydrocarbons from removal. wrwr* w* cant overcam* them.*extracted from th* soft along with th* thereby allowing mem to csntinu* con- Third-party experience. OfficialsVOCs. One* extracted, the two laminating groundwatar. at Texas instruments (Tl; Dallas) arephases flow to a separator, which r*> With lighter-than-water conrami- tru* believers in OVE's potential.moves contaminated water, Contami- nants. th* residual sinks only as far as according to Michael STwtt, th*natcd air continues on to a vapor treat- th* water table's lowest level. With pany's environmental tngin«~ment system, sucn as activated car- heavier contaminants, tft* smear zon* manager for the Materials anebon or catalytic oxidation. can extend "very deep into th* aqui- trots Grouo (Attlebora. Mass.). TT

OVE systems are virtually th* fer,* Malot says, tn most cases, pump a two-phase vacuum extraction

a* HAZMATWORLOHR3I23I9

Ouai vacuum extraction process

-ex--)-

technique at a facility in Central Lake, soots, he adds, which will be deaned groundwater recovery and liabilityMien., and OVE at a sita in The on* at a time. The only problems en- should be relatively obvious.' MalotNetherlands. countered there involved iron fouling of contends. Efliott agrees, predicting that

At th* Central Lake facility, th* th* equipment, but These are typical widespread us* of OVE 'is only acompany faced trichloroethylen* problems for any groundwater pump- matter of time.*(TCS) contamination in th* subsurface ing system and can be overcome,' he *! think for instance if s _ only ._ insoil and groundwater. Rather than use says. Additionally, he says, trie Gar- the last few years the importance ofOVE initially, the company first used man company that performed the pro- the smaar zon* has com* to bevacuum extraction, then attacked the cess initially injected air into the water known,* Effiott contends. The sciencegroundwater contamination with OVE. ' table, but this aggravated trie iron ore- of what happens to organic contami-OVE was not an option originally dpitation and was stopped. Terra Vac, nants when they reach the differentbecause of state regulations, but 1 am Biott notes, does not use or recom- subsurface layers ... has only justconvinced had we used dual-phase mend reinjecting air into a system. started to became a topic of research.vacuum extraction it would have saved "We looked into btoremediation but Until a few years ago. people thoughtus considerable time and money,* ... basically w* didn't feet comfortable of contaminants as either 'sinkers' orEUiott says. Initial TCE concentrations with th* concept* SHott explains. It floaters.' Sinkers were supposed toin the groundwater were 300 poo. Sd dldnt offer the same degree of con- sink easily into the saturated zone.vacuum extraction cut the concert- troT as OVE, he concludes. The com- while floaters remained on the surface.tration in half. When the groundwater party also considered pump and treat. Now we realize contaminant move-phase began in 1 990, TCS concert- . but concluded the technique was too , ment depends on many faears. indud-trations were 250 ppo, Since tttfru_ passive and wouldn't aggressively ' ing the physical and chemical char-tney have been rjciii |J» about i<QQ attack tr» source" of contamination. aeteristics of -the contaminants and theppa on their v¥ayJB| Sw" standard' " AdcStionatty, SHSott says. OVE costs soa media ttwouott wnicn they migrate.of 3 ppb. The lig Ejbv exp*ets are reasonable. For example, he says. it seems there is three to five yearsgroundwater desrjjfa The i-»cr* site the soil vacuum extraction phase at lag time between when a techniqueto tak* about lO tBf ft conduqe ~ th* Central Lake facility cost about appeals in the literature and when it is

At the site in The N«th*rtands. $160.0X30. and th* groundwater phase reject-id or accepted.* Sfkjt says. Tm _where groundwater Is practically at has cost about Si 00.000, including starting to see now literatur* on howthe surface, what we saw ... was annual operating costs at between contaminants behave differently asabsolutely incredible.* Eiliott relates. S1 5.000 and 320,000. In The Nether- they encounter different subsurfaceInitially, groundwater there contained lands, the company made an initial features. As w* «votv« in our appii-about 1 .100 ppo at TCE. After one investment of S30.0QO, out operating cation erf remediatian processes andyear of operation using OVE. TCS costs are less than in Central take tailor them to specific contaminants;conc*ntrations have been reduced to because that country's monitoring and sttee, there w* be greater appre--100 ppa. (The company currently is requirements are less stringent than ciationfer techniques fit* OVE.*conducting a risk assessment to here, he reports. Additionally, he says, th* next fivedetermine an appropriate cleanup Although use of OVE is not wide- to 10 years will provide mare OVElevel. Sliott says.) The site contains spread, Matat and Eiliott firmly believe success stories in the literature, whichthree or four one-quarter acre hot its tim* will com*. *Th* impact on wW further increase its acceptance. •*

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