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Large watershed managementand restoration: dioxin sedimentremediation case studyJacob W. VanHoutena

a Science Division, Delta College, 1961 Delta Road, UniversityCenter, MI, 48710, USAPublished online: 29 Jul 2014.

To cite this article: Jacob W. VanHouten (2014) Large watershed management and restoration:dioxin sediment remediation case study, International Journal of Environmental Studies, 71:4,570-577, DOI: 10.1080/00207233.2014.940127

To link to this article: http://dx.doi.org/10.1080/00207233.2014.940127

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Large watershed management and restoration:dioxin sediment remediation case study

JACOB W. VANHOUTEN*

Science Division, Delta College, 1961 Delta Road, University Center, MI, 48710, USA

This paper reviews continuing, long-term remediation of river sediments containing dioxin andother chemical compounds in a large watershed of the Great Lakes Region. Chlorinated dibenzo-p-dioxins are a ‘family’ of chemically related compounds commonly known as chlorinated dioxins orsimply, dioxins. The highest levels are usually found in sediments, soil and animal fats. The mosttoxic chemical in this group is 2,3,7,8-tetrachlorodibenzo-para-dioxin, the ‘standard’ to which otherdioxins are compared and which has been shown to be very toxic in animal studies. The US Envi-ronmental Protection Agency (EPA) and Michigan Department of Environmental Quality (MDEQ)have made a lengthy effort to assess and remediate portions of the Saginaw Bay Watershed, includ-ing the Tittabawassee River. The paper reviews the EPA-proposed ‘phased approach’ to restorationand remediation of a short segment (Segment 1) of the Tittabawassee River sediments. Sedimentsare contaminated with a number of chemical pollutants other than dioxins, including arsenic, chol-orbenzenes, cholorphenols, ethyl parathion, o-phenylphenol and polycyclic aromatic hydrocarbons.The paper evaluates three proposed ‘cleanup alternatives’, with final action method suggested basedon effectiveness, feasibility for implementation and cost.

Keywords: Dioxin; Sediments; Watershed; Restoration; 2,3,7,8-TCDD

1. Introduction

The objectives of this paper are to review continuing, long-term dioxin sediment and soilremediation/restoration efforts in a large watershed in the Great Lakes Region. The DowChemical Company (Dow) has been in operation along the banks of the TittabawasseeRiver since the late 1890s [1,2]. Contaminants, including dioxins and furans, have beendetected in and along the Tittabawassee and Saginaw Rivers, as well as the SaginawBay in Lake Huron. The Dow facility’s past waste management practices have in part(other industries have also contributed), led to the deposition of dioxin(s) and othercontaminates [3].

The most recent studies have focused on 2,3,7,8-tetrachlorobeno-para-dioxin or ‘TCDD’which ultimately led to interim remedial action (IRAs) by both the state regulatory agency,Michigan Department of Environmental Quality (MDEQ; formerly the MichiganDepartment of Natural Resources, MDNR), and the US Environmental Protection Agency(EPA) [4]. In January 2010, legal agreements between Dow, the EPA and the MDEQresulted in Dow conducting investigations and development/design of clean-up (restora-tion) options which were selected by EPA in consultation with the MDEQ. The aim was

*Email: jwvanhou@delta.edu

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to find the clean-up option best suited to protect human health and the environment of theTittabawassee and Saginaw Rivers as well as the Saginaw Bay in Lake Huron.

The work on ‘Segment 1’ of the Tittabawassee River has been proposed by the EPA andthe Dow Chemical Company as a first step in a long-term process [5]. The TittabawasseeRiver and the upper Saginaw River, indicated in figure 1, were divided into eight segmentsranging in length from three to five miles (5–8 km). The proposed work will be conducted instages (upstream to downstream, segment by segment). Segment 1 is the most ‘upstream’segment as it runs through the Dow Chemical manufacturing facility in Midland, Michigan(figure 1). It is about three miles (5 km) in length and is further divided into Reach A throughH (eight subsections). Major remedial activity has previously taken place in Segment 1. InReach B, dioxin-contaminated debris in the river and riverbank soil were removed and dis-posed of and river sediment was capped [6]. In Reach D, sediment containing dioxin and

Figure 1. Features within Segment 1, Tittabawassee River [10].

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other contaminants was dredged and the area was capped [7]. Reach G had sheet pilecontainment systems installed to isolate a sand bar containing Dense Non-Aqueous PhaseLiquid (DNAPL) and other contaminants within the sediment being collected and treated [8].This paper will review and examine the proposed EPA plan for remediation of a pollutedriver section referred to as ‘Segment 1’. The plan is part of the Comprehensive Environmen-tal Response Compensation and Liability Act (CERCLA or Superfund) Tittabawassee River,Saginaw River and Bay Site response. It is a US National Priority List (NPL) site located inMidland, Saginaw and Bay City, Michigan, USA [9].

As of summer 2012, clean-up of contaminated sediment is underway in Segment 1, thethree-mile stretch of the Tittabawassee River closest to the Dow Chemical Plant inMidland, Michigan, USA. A clean-up plan has also been proposed for Segment 2, afour-mile stretch of the Tittabawassee River, which will begin during the summer of 2013.

2. Materials and methods

2.1. Segment 1 contamination

Extensive, numerous investigations have been done on Segment 1. Thousands of samplesfrom hundreds of locations for more than 180 chemicals, including dioxins and furans, aswell as sediment stability studies and biological evaluations/toxicological studies have beenconducted on this segment. Conditions in Segment 1, as they exist now, are unique whencompared with the rest of the Tittabawassee River, Saginaw River and Saginaw Bay LakeHuron site. Dioxins, primarily furans, are the major contaminant in the rest of the site,while the Segment now has lower concentrations of dioxins due to the past clean-ups con-ducted previously in Reaches B, D and G. Segment 1 has six other chemicals or chemicalgroups that are now considered ‘key contaminants’. These include Arsenic, chlorobenz-enes, chlorophenols, ethyl parathion, o-phenylphenol and polycyclic aromatic hydrocarbons(PAHs) [11]. These six pollutants are not found everywhere in Segment 1 and are notalways found together, as well as being found in different levels of the sediments (surface,below sediment surface but above till: the hard geologic deposit under the sediment inmost of the Tittabawassee River) [12].

EPA and MDEQ have identified six distinct areas within Segment 1 where high levelsof pollutants in sediments require clean-up. Table 1 shows key contaminants and theirdistributions within Sediment Management Areas (SMAs) of Segment 1 [13].

2.2. Summary of proposed clean-up alternative methods

For developing remediation options, EPA grouped SMAs 2 and 3 together, and 4 and 5together due to similar characteristics. SMAs 1 and 6 were evaluated individually (seefigure 2). Three alternative remediation methods were considered. Several clean-up/remedialtechniques have been combined to develop each alternative. These included the following:

� Capping (placing clean material such as sand or gravel over contaminated sedimentwith some caps containing compounds like organoclays or activated carbon to treatcontaminants. Caps can include a layer to prevent erosion as well) [14,15];

� Containment systems (isolating contaminated sediment with sheet pile walls andbeneath cap, combined with DNAPL removal, treatment and hydraulic control andtreatment) [16];

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� DNAPL removal and treatment (capturing DNAPL in sump and well, removing it fromthe river system and treating it);

� Dredging (removing sediment by mechanical or hydraulic equipment) [17];� Hydraulic control and treatment (connecting to existing ground water collection sys-

tem at Dow plant operations, or pumping wells to capture water within the sediments);

Table 1. Key contaminants and distributions driving remediation within SMAs.

SMA Surface sediment Deeper sediment DNAPL above till

1 Arsenic and PAHs – No2 Mostly chlorobenzenes, also

chlorophenoisMostly chlorobenzenes andother volatile organics

Yes

3 Mostly chlorobenzenes, alsochlorophenols, PAHs and o-phenylphenol

Mostly chlorobenzenes Yes

4 – Mostly chlorobenzenes No, but additionalinvestigationscontinuing

5 – Mostly chlorobenzenes No, but additionalinvestigationscontinuing

6 Ethyl parathion in one area Mostly chlorobenzenes Yes

Figure 2. Conditions found at SMAs 1–6.

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� Monitored natural recovery (relying on natural chemical, physical or biological pro-cesses such as decay, burial and dilution to reduce contaminant levels and health risksover time) [18].

Evaluation of alternatives for remediation is required of EPA using the following crite-ria: effectiveness, implementation and cost. Table 2 contains clean-up/remedial alternativesfor each Sediment Management Area. Each alternative shares some features and therefore,EPA evaluates each to understand current conditions on site and feasibility of each. Workis expected to require ‘two construction seasons’ to complete.

3. Results and discussion

To meet the EPA’s requirement for evaluation of options for remedial activity, each alterna-tive action was compared against the effectiveness, implementation and cost criteria. ‘Effec-tiveness’ means whether an option protects human health and the environment. Otherconsiderations include compliance with laws, regulations and other criteria, advisory noticesand guidance; long-term effectiveness and permanence; reduction of toxicity, mobility orvolume through treatment; and short-term effectiveness. ‘Implementation’ means how diffi-cult the option will be to complete with technical and administrative feasibility; and

Table 2. Clean-up alternatives for each sediment management area.

Sediment managementarea for alternatives Alternative 1

Alternative 2 (EPA’srecommendation options) Alternative 3

1 Monitored naturalrecovery

Cap Dredge sedimentand dispose

2 and 3 � Containmentsystem (sheet pileand cap)

� Hydraulic controland treatment

� DNAPL removaland treatment

� Containmentsystem (sheet pileand cap)

� Hydraulic controland treatment

� Dredgesedimentand dispose

� Capresiduals

4 and 5 Monitored naturalrecovery

Cap � Dredgesedimentand dispose

� Capresiduals

6 � Dredge/disposeethyl parathionsediment

� DNAPL removaland treatment

� Dredge/disposeethyl parathionsediment

� DNAPL removaland treatment

� Containmentsystem (sheet pileand cap)

� Hydraulic controland treatment

� Dredgesedimentand dispose

� Capresiduals

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availability of services, materials and state/community acceptance. ‘Cost’ meansconstruction (equipment, materials and labour) as well as long-term maintenance and moni-toring costs, among others. A summary of EPA’s evaluation for each criterion is presentedbelow:

3.1. Effectiveness

All alternatives for each SMA are expected to protect public health and environment. Eachwill also comply, as needed, with all laws, regulations and other criteria (health and safetyplans, contingency planning and decontamination). Contaminant location within the sedi-ment – surface vs. depth – will influence the effectiveness of remedial activities. Presenceof DNAPL constituents will also influence clean-up options. Anticipated effectivenessdifferences are described below.

Reduction of toxicity, mobility or volume through treatment: Alternatives 1 and 2 forSMAs 2, 3 and 6 reduce toxicity and volume through treatment of contaminated material.Alternative 2 provides greater treatment than alternative 1 for these SMAs and destroysthe DNAPL. The other options do not meet this criterion through treatment.

Short-term effectiveness: All options except monitored natural recovery may have someshort-term potential movement of contaminants downstream via the water column and bedload.

Long-term permanence and effectiveness: All alternatives for each SMA are expected toprovide long-term effectiveness. The time frame to attain protective levels is more uncer-tain for options that rely on monitored natural recovery. Capping options may allow forbeneficial habitat enhancement as well [19].

3.2. Implementation

All alternatives are expected to be ‘administratively’ feasible. Similar remedial alternativesproposed for Segment 1 SMAs have been successfully used in other areas along the Titta-bawassee River, indicating that they all can be implemented. The technical feasibility ofthe alternatives differs. DNAPLs are often difficult to locate [20], and are a challenge toclean up or remove, especially with the use of dredging. Sediment removal by dredging inthe Tittabawassee River has been shown to be difficult [21]. Alternative 3 presents chal-lenges such as managing river flow for underwater work; avoiding water impact duringremoval; managing water removed from dredged sediments; and dredging above the ‘till’.

3.3. Cost

EPA estimates total cost for the recommended option/alternative to be almost $6 million.Uncertainties around all three alternatives are largely due to management of dredged sedi-ment prior to disposal and/or treatment.

4. Conclusions

After this review, it is concluded that the regulatory agencies have conducted thorough,appropriate and extensive assessment of remedial options. Based on this, the EPA andMDEQ have supported their conclusions for this complex project. Further assessmentshould lead to improved implementation of similar remedial options on other sections of

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the system. Section 117(a) of the Comprehensive Environmental Response, Compensationand Liability Act (CERCLA) requires the EPA to provide an opportunity for public inputwith a comment period. The EPA and MDEQ made a decision concerning the alternativeselected as a ‘final’ remedial action following a review of public hearing/public comment,August 31, 2011. The work already done and what is under consideration is outlinedbelow. The EPA and MDEQ have oversight of the project, and the Dow Chemical Com-pany implemented the work on Segment 1 in early 2012. During this work, specific anddetailed engineering designs were completed as well as potential identification of otherSMAs within Segment 1 which may need similar remediation methods.

The work during 2012 focused on removing and treating the DNAPL in three SMAs.Recovery wells were installed to remove the DNAPL from the river benthos. This tech-nique has been very successful, with more than 8000 liters removed. Dow has used itsRCRA Part-B permit incinerator to destroy the DNAPL. Work was expected to be con-cluded during 2013.

EPA has made several recommendations for clean-up steps/remedial activity surroundingSMAs within Segment 1 on the Tittabawassee River. The following remedial activitieshave taken place:

(1) SMA 1: Clean cap placement over contaminated sediment for isolation/stabilization.(2) SMAs 2 and 3: Removal and treatment of dense non-aqueous phase liquid or

DNAPL; isolation with sheet pile and cap, capturing water within the sediment(hydraulic control) for treatment.

(3) SMAs 4 and 5: Clean capping over contaminated sediment.(4) SMA 6: Dredging and disposal of ethyl parathion-contaminated sediment; removal

and treatment DNAPL; isolation of remaining contaminated sediment with sheetpile and cap; and hydraulic control and water treatment.

(5) Treatment and disposal of above materials at ‘approved’ locations.(6) Monitoring during and after clean-up/remediation work.(7) Operation and maintenance of clean-up systems.

Early clean-up actions took place in Segment 2 along areas of the river known asReaches J and K to remove sediment and soil along the riverbank and to stabilize the riv-erbank in Reaches M and O. In Reach K, an innovative approach was made to stabilizeburied contaminants by placing a grid-shaped Geocell material on top of sediment depos-its, thereby allowing clean material to fill the grids and remain in place with monitoring.Detailed clean-up documents can be viewed on the internet [22].

NomenclatureEPA Environmental Protection AgencyMDEQ Michigan Department of Environmental QualitySMA(s) Sediment Management AreasPAHs Polycyclic aromatic hydrocarbons2,3,7,8-

TCDD2,3,7,8-tetrachlorodibenzo-para-dioxin

DNAPL Dense non-aqueous phase liquidCERCLA Comprehensive Environmental Response Compensation and Liability Act

(Superfund)

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Acknowledgements

The author gratefully acknowledges the assistance provided by Patricia Krause, EPARegion 5, Community Involvement Coordinators, Saginaw, Michigan USA; the UnitedStates Environmental Protection Agency, Region 5, Superfund Division, Chicago, Illinois,USA; the Michigan Department of Environmental Quality; Community Advisory Group(CAG); and the Dow Chemical Company. Public domain documents were provided forreference during this review.

References

[1] Brandt, E.N., 1997, Growth Company: Dow Chemical’s First Century (East Lansing, MI: Michigan StateUniversity).

[2] Dow, H.H., 1926, Midland Sun: Portraying the City of Midland, Home of America’s Greatest ChemicalInstitution. In: Why I came to Midland, 2nd edn (Midland, MI: Home of America’s Greatest ChemicalInstitution).

[3] ENVIRON, 2008, Current Conditions Report for the Tittabawassee River (Midland, MI: ENVIRONCorporation).

[4] VanHouten, J.W., 2009, Dioxin assessment in a river flood plain: soil and sediment. Journal of ASTMInternational, 6(7), 2–3.

[5] Dow Chemical Company, 2011, Tittabawassee River Segment 1 (OU1) Response Proposal (Dow ChemicalRiver Response Team, April 14 Issue).

[6] URS, 2009, H-14 Compliance Schedule Activity, Tittabawassee River – Reach B Pilot Cap Monitoring Plan(December 15 Issue).

[7] URS, 2008, Reach D – Tittabawassee River – Final Report (March 19 Issue).[8] URS, 2009, Sediment Cap Installation and Temporary Sheet Piling Removal Plan (January 30 Issue 9).[9] EPA, 1988, Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA:

Interim Final (United States Environmental Protection Agency, October Issue).[10] EPA, 2011, EPA Proposes Cleanup Plan for Polluted River Section, Tittabawassee River, Saginaw River and

Bay Site Segment 1 Midland, Saginaw and Bay City, Michigan (August Issue).[11] EPA, 2007, Reach D Project Characterization Plan (March 19).[12] Radian International, 2000, Identification and Description of Glacial Till Sand Units in Areas the

Tittabawassee River (April Issue).[13] ATS, 2009, Final GeoMorph Pilot Site Characterization Report, Volume I-VI, Upper Tittabawassee River

and Floodplain Soils Midland Michigan (Ann Arbor, MI: Ann Arbor Technical Services, Inc, June 15Issue).

[14] Anchor QEA, 2009, Reach B Tittabawassee River, Basis for Offshore Cap Design (July Issue).[15] Lambert, D.J. and Reible, D., 2009, An analytical modeling approach for evaluation of capping of

contaminated sediments. Soil and Sediment Contamination: An International Journal, 18(4), 470–488.[16] Sanchez, F.F., Thibodeaux, L.J., Valsaraj, K.T. and Reible, D.D., 2002, Multimedia chemical fate for

environmental dredging. Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management,120–128.

[17] Desrosiers, R. and Patmont, C., 2009, Environmental dredging residuals – case study summaries andanalyses. In: G.S. Durell and E.A. Foote (Eds.) Remediation of Contaminated Sediments (Columbus, OH:Battelle Memorial Institute), pp. 23–26.

[18] Enggleton, J. and Thomas, K.V., 2004, A review of factors affecting the release of bioavailability ofcontaminates during sediment disturbance events. Environ International, 30, 973–980.

[19] EPA, 2004, Contaminated Sediment Remediation Guidance for Hazardous Waste Sites, OSWER Directive9355.0-85 (United States Environmental Protection Agency, EPA-540-R-05-012, December Issue).

[20] Patmont, C. and Palermo, M., 2007, Case studies in environmental dredging residuals and implications.Paper D-066 in Proceedings, 4th International Conference on Remediation of Contaminated Sediments(Savannah, GA: Battelle Press), Columbus, OH, 22–25 January, January Issue.

[21] National Research Council (NRC), 2007, Sediment Dredging at SUPERFUND MEGASITES – Assessing theEffectiveness (Washington, DC: National Academy Press).

[22] Available online at: www.epa.gov/region5/cleanup/dowchemical.

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