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Keywords:

  • Dredged material;
  • Contaminated sediment;
  • Beneficial use Embankments

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

Since the 1997 local ban on ocean dumping of dredged sediments, the state of New Jersey has pursued a policy of environmentally sound solutions to the controversial problem of dredged material management, including beneficial use of dredged material stabilized with pozzolanic additives (SDM). A pilot study was initiated in 1998 to evaluate the use of SDM in the construction of highway embankments. Using 80,000 cubic yards of silty dredged material, 2 embankments were constructed from SDM on a commercial development area adjacent to the New York/New Jersey Harbor. This article presents the evaluation of the environmental effects of the SDM, including fugitive air emissions, leachate, and stormwater quality. Engineering properties, handling and management techniques of the SDM, constructability, and performance were also evaluated, the results of which are published elsewhere. The findings demonstrate that although there are measurable releases of contaminants to the environment from the SDM, these releases are not significant long-term threats to human health or the environment. Policies currently in place to regulate the management of SDM that include limiting placement options to previously contaminated sites with institutional and engineering controls will further reduce the potential for environmental impact and, in fact, have the potential to produce significant environmental benefit.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

The Port of New York and New Jersey is the largest port on the East Coast of the United States, situated in the metropolitan center of the Hudson-Raritan Estuary complex (Figure 1). The New York/New Jersey Harbor (NY/NJ Harbor) complex is naturally shallow, with an average depth of 6 m at low tide. Because of the Port's strategic position in regional and international trade, the U.S. Army Corps of Engineers has constructed and maintains approximately 400 km of engineered waterways at depths ranging from 6–14 m. Plans are underway to deepen the main channels to 16 m during this decade. Maintenance of these waterways, crucial to safe navigation, requires dredging 3–5 million m3 of sediment or “dredged material” annually (USACE 1999). Unfortunately, at least half of the material scheduled for removal is contaminated with industrial chemicals and trace metals from historical and ongoing sources at levels that limit management options.

Historically, dredged material from the harbor was either relocated nearby, used to fill in shallows, or dumped in the ocean (McDonough et al. 1999). Since 1997, when strict, new environmental standards were adopted that limited the use of ocean disposal, the NY/NJ Harbor region has pursued a policy of environmentally sound beneficial use of dredged material. The primary management strategy has been the use of stabilized dredged material (SDM) as a capping or filling material for landfills, industrial sites, and abandoned mines (Douglas et al. 2003). SDM is dredged material that has been mixed with a pozzolanic additive such as Type II portland cement, coal fly ash, or incinerator ash to achieve a soil-like mixture.

One of the 1st placement sites for SDM in the NY/NJ Harbor was the Elizabeth Landfill in Elizabeth, New Jersey, USA (Figure 2). The 67-ha municipal and industrial landfill had been abandoned for decades and was never properly closed (no slurry wall, impermeable cap, or leachate collection system). Improperly closed or abandoned landfills are known to contribute contaminants to the harbor complex through leachate and stormwater runoff. During a remedial process that included the installation of leachate and stormwater collection systems, deep dynamic compaction and grading, capping of contaminated soils, off-site disposal of hazardous waste and wetlands creation, more than 600,000 m3 of raw dredged material (RDM) was converted into SDM and used as fill. The remediated site was then sold for commercial development that includes a 2-story shopping mall and a parking lot, 3 hotels, and a movie theater. Future plans include office towers and a marina.

During the course of the Elizabeth project, the New Jersey Department of Transportation/Office of Maritime Resources (NJDOT/OMR) initiated a pilot study to evaluate the feasibility of SDM as a fill material for roadway embankments. The feasibility study was designed to describe multiple aspects of the practical use of SDM in NJDOT projects including constructability, geotechnical limitations, economics, and environmental or human health impacts. Two embankments with access roads were constructed at the Elizabeth site using 60,000 m3 of SDM as the fill material. This article presents the environmental aspects of the embankment study including the characterization of dredged material; the prepared SDM; the leachate, runoff, and percolated water; and the fugitive air emissions, with a comparison to applicable regulatory standards used in the NY/NJ Harbor region. Constructability, geotechnical, and economic aspects of the embankment study are presented elsewhere (Sadat Associates 2001; Maher et al. 2004, 2005).

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Figure Figure 1.. New York/New Jersey Harbor.

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METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

Site characterization

The site chosen for this study was a portion of an abandoned solid waste landfill that ceased operations in the 1940s. The refuse fill, covered by approximately 1 foot of cover soil, ranged in depth from 2.4–6 m over a layer of peat and soft marsh sediments. Before construction of the berms, shallow compaction was attempted to stabilize the foundation soils; however, there was insufficient time and funds to perform dynamic compaction on this part of the site in advance of the project. Because of the heterogeneous nature of the waste fill and its thickness, the marginal engineering properties of the underlying marsh soils, and in the absence of deep dynamic compaction, it was decided that a geotextile layer be placed directly under each embankment to guard against differential settlement not attributable to the use of SDM. This boundary layer had the added benefit to the project of ensuring that water quality data collected in the study would not be influenced by contamination in the historical fill materials. It is important to note that it is unlikely that an artificial membrane would be used in practice, but it is just as unlikely that a roadway would be constructed on a landfill.

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Figure Figure 2.. Site locations in New York/New Jersey Harbor.

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Dredged material preparation

Approximately 60,000 m3 of sediment was dredged from a dry dock facility in Hoboken, New Jersey, USA, along the Hudson River. The sediment was typical of estuarine sediments, with >90% being classified as silt and clay according to Unified Soil Classification System. Sediment was transported to a stabilization facility by barge, screened for debris, and offloaded into a pug mill. Approximately 8% (wet weight) Type II cement was mixed into the sediment by the pug mill to stabilize the sediment. Because of scheduling constraints and the onset of winter, sediment was stockpiled uncovered on the site for 4 months before the initiation of construction.

This is not an ideal situation but accurately reflects regional experiences of the logistical difficulties encountered when combining disparate upland and marine construction activities.

Dredged material characterization

The sediment at the dredging site was characterized before removal using a compositing scheme that combined 13 discrete vibracore samples into 4 composite samples. These composites were then subjected to bulk sediment analysis following USEPA SW-846 methodology using inductively coupled plasma, gas chromatography-mass spectroscopy, and high-performance liquid chromatography as appropriate to reach detection limits according to New Jersey Department of Environmental Protection (NJDEP) guidelines (NJDEP 1997). Each composite was also analyzed for total organic carbon and grain size by hydrometer method. Additionally, a split of each composite sample was stabilized with 8% Type II cement in the laboratory and analyzed for the same parameters, as well as subjected to a multiple extract procedure (MEP) that simulates rainfall leachate. Samples were also taken of the stockpiled material in the winter of 1999 and analyzed for the more traditional toxicity characteristic leaching procedure. Three additional composite samples of SDM were taken from the stockpile during the construction process and analyzed for full bulk sediment and MEP parameters to verify the initial concentration of contaminants.

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Figure Figure 3.. Plan of embankments constructed with stabilized dredged material (SDM) showing environmental sampling points.

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Construction of berms

Two earthen berms were constructed with SDM, using standard earth-moving equipment. The embankments occupied approximately 1 ha of the site, adjacent to, but not coincident with, the area of the landfill that received deep dynamic compaction. The SDM was placed in 0.3–0.5 m lifts, aerated, and compacted in place. Embankment 1 was 190 m long, 40 m wide at the top, 55 m wide at the base, and a maximum of 3 m above grade. Embankment 2 was 177 m long, 27 m wide at the top, 46 m wide at the base, and a maximum of 4 m above grade. Asphalt millings were placed in a single 0.15 m lift as final cover for the top and access ramps of each berm to simulate actual roadways. A single, 0.15 m lift of clean soil was used to cover the side slope of each berm and hydroseeded, again to simulate minimum anticipated construction procedures.

Water quality monitoring

To monitor the potential for release of contaminants, each berm contained a leachate and stormwater collection system (Figure 3). The leachate-collection system consisted of trenches 1 m wide and 0.4 m deep, containing 1 cm crushed stone crossing the width of the berm, directing water into a main 10 cm, PVC, perforated collection pipe. A single manhole served to provide access to the discharge points of each embankment. A slope of 0.15% was maintained for both systems. Samples taken from these systems were called “percolated water” to distinguish them from “laboratory generated leachate” or “SDM stockpile leachate.” Stormwater ditches were created around each embankment, were covered with 15 cm of topsoil, and were hydroseeded. Three samples of percolated water were collected during the study along with 7 stormwater samples, both during and following construction. These samples were analyzed for the same constituents as the RDM and SDM (volatiles, semivolatiles, pesticides, metals, and dioxins or furans) using similar methods (see the Dredged material characterization).

Air quality monitoring

Area and personal samples were collected during the study to ascertain if the use of SDM would potentially lead to exposing the surrounding community or workers to elevated airborne levels of dust, trace metals, PAHs, or PCBs. A weather monitoring station (Weather Monitor II, Davis Instruments, Hayward, CA, USA) was erected near the embankments to monitor temperature, wind speed, and wind direction.

Personnel air monitoring was performed using constant low-flow pumps fitted with analyte-specific sampling filters and media (SKC Aircheck, Houston, TX, USA, or Ametek-Rotron, Model MG-4, Kent, OH, USA). Devices were carried by both workers operating heavy equipment and personnel on the ground manipulating SDM manually. Samplers were analyzed for trace metals (NIOSH Method 7300), pesticides, PCBs (NIOSH Method 5503), and PAHs (NIOSH Method 5506/5515) during 2 d of work, exclusive of lunch. Respirable dust (PM10) was sampled for 2 h out of each sampling day according to NIOSH 0600. Personal pumps were calibrated to confirm nominal flow rates of 2.2 L/m particles, 1.9 L/m PAH and metals, and 0.8 L/m PCB.

Area samples were taken during active construction using high-volume area samplers (USEPA 1983) as composites over 3 to 6 d at a flow rate of 10 to 30 cfm (Graseby-Anderson sampler, General Metal Works, Palatine, IL, USA). Each sampler was fitted with both a glass fiber filter for total suspended particulates and a polyurethane foam filter for capture of vapor phase contaminants (0.049 g/cm3 density). Two to 4 sampling devices were used for each event, sampling upwind and downwind from the site, as well as crosswind (if appropriate). Devices were positioned approximately 46 m from the edge of the construction site.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

RDM and SDM

In keeping with current NJDEP guidelines for the evaluation of dredged material proposed for upland beneficial use, samples of RDM and laboratory-prepared SDM were evaluated. The raw sediment was typical of NY/NJ Harbor maintenance sediment, with moderate concentrations of metals, PAHs, pesticides, and PCBs; very low concentrations of dioxins and furans; and no detectable volatile organics (Table 1). Laboratory-prepared SDM was slightly less contaminated than RDM on average, but this is more likely the result of analytical variability or dilution (with pozzolanic additives) rather than any loss of contaminants from treatment. Field-stockpiled SDM differed somewhat from laboratory-prepared SDM, with some constituents being higher (PAHs) and some lower (PCBs, pesticides, dioxin, and furan), and with the metals showing essentially no change. This inconsistency leads us to suspect either analytical or sampling variability rather than a significant loss of contaminants during storage. In all cases, only minor excursions from the New Jersey residential direct-contact soil cleanup criteria (RDCSCC) (NJDEP 1997) and nonresidential direct contact soil cleanup criteria (NRDSCC) (NJDEP 1997) were observed, and those minor excursions were only for PAHs. These concentrations were well within the NJDEP acceptance criteria for the Elizabeth site. No exceedances of the New Jersey Impacts to Groundwater-Soil Cleanup Criteria (NJDEP 1997) were observed. MEP leachate analysis on the laboratory-prepared SDM indicated only 1 excursion from groundwater criteria for mercury (Hg), but it was observed only in the 1st extract and quickly dropped below the criteria (Table 2). A partial MEP analysis was performed on 3 samples of the stockpiled SDM during construction (Table 2). Only arsenic (As) was observed at concentrations above criteria, but only the 1st extract was analyzed. It is interesting to note that no manganese (Mn) or lead (Pb) was observed in the leachate of any of the 3 stockpile samples.

Percolated and stormwater samples

Percolated water collected at the site showed concentrations of As, Mn, nickel (Ni), and Pb at concentrations above groundwater criteria during construction, but only Mn and As were observed to exceed criteria in the leachate after the completion of construction (Table 2). No volatile or semivolatile compounds were observed in leachate above detection limits. Concentrations of some metals in surfacewater runoff were elevated during construction, but concentrations were shown to decrease markedly after construction with only As and copper (Cu) being elevated above applicable surfacewater quality standards at the end of the study (Table 3). No volatiles, semivolatiles, or pesticides were observed in surfacewater runoff at levels above the NJDEP-specified detection limits (NJDEP 1997) at any time.

Air monitoring

As might be expected from a construction site that was engaged in earth-moving activities, dust was detected during sampling at concentrations ranging from 0.1 to 1.16 mg/m3 (Table 4). The PM10 results were within a factor of 2 to 4 of the total suspended particle results, indicating that a considerable portion of the dust was of respirable size. The concentrations of particles exceeded air quality standards (0.05–0.75 mg/m3) for 24 h/12 month averages, but concentrations did not violate any industrial safety standards (8-h exposure), which range from 3 to 5 mg/m3. The concentrations of all contaminants measured in either the particulate or vapor phase were extremely low, typically several orders of magnitude below industrial health standards.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

Surfacewater impacts

No volatile or semivolatile compounds were detected at concentrations exceeding surfacewater criteria. However, metals (Hg, Pb, Mn, As, and Cu) were detected at concentrations that exceeded the surfacewater criteria. Although this is not desirable, the runoff from a construction site is not considered a direct discharge. To evaluate the potential for stormwater to impact surfacewater quality, the pathway to the nearest surfacewater body (Newark Bay) was determined, infiltration estimated, and potential for dilution in the receiving water calculated. It was encouraging to note that concentrations of metals detected in stormwater diminished markedly after construction was completed with only As and Cu exceeding surfacewater criteria (Table 3). Note that there was no control plot for this study, raising a question that the observed metals might have been from precipitation or airborne dusts originating off site. A simple dilution model using average flows and a 10-y storm clearly showed that the mass of contaminants expected to be transported under a worst-case scenario was 1 to 5 orders of magnitude lower than that required to impact water quality in Newark Bay. Given that, in practice, the use of SDM in highway construction will require a 1-m cap on side slopes for geotechnical reasons (to guard against freeze-thaw, Maher et al. 2005) and that the top of the berm will be covered with an impermeable surface (macadam), the potential for surfacewater impacts from eroding SDM are unlikely once the project has been completed. In addition, state policy on the use of SDM has limited it to use on contaminated sites that typically have surface concentrations at least as high, often higher, than those seen in SDM.

Table Table 1.. Chemical characteristics of raw dredged material (RDM), laboratory stabilized dredged material (SDM), and stockpiled SDM used in embankmentsab
  1. a Nondetects were treated as 1/2 the method detection limit. Bold numbers indicate exceedance of applicable cleanup criteria

  2. b RDCSCC = New Jersey (USA) Residential Direct Contact Soil Cleanup Criteria; NRDCSCC = New Jersey Nonresidential Direct Contact Soil Cleanup Criteria; IGWSCC = New Jersey Impacts to Groundwater Soil Cleanup Criteria; TEQ = 2,3,7,8-TCDD Toxic Equivalents; Ag = silver; As = arsenic; Ba = barium; Cd = cadmium; Co = cobalt; Cr = chromium; Cu = copper; Hg = mercury; Mn = manganese; Ni = nickel; Pb = lead; Se = selenium; Zn = zinc; NA = not applicable.

Chemical (dry weight basis)NJ RDCSCCNJ NRDCSCCNJ IGWSCCAverage RDM (N = 4)Average Laboratory SDM (N = 4)Average Stockpile SDM (N = 3)
Ag mg/kg1104,100s4.403.751.22
As mg/kg2020I14.5018.8834.83
Ba mg/kg70047,000t101105.73113.33
Cd mg/kg39100e0.050.073.44
Co mg/kgNANA 17.5017.5516.97
Cr mg/kg120,000120,000s98.50108.18111.20
Cu mg/kg600600p373239.50200.33
Hg mg/kg14270e1.631.251.87
Mn mg/kgNANAc765653.25804.33
Ni mg/kg2502,400I80.5057.4052.20
Pb mg/kg400600f307255232.67
Se mg/kg633,100I0.881.020.54
Zn mg/kg1,5001,500c1,160827.25606.67
Acenaphthene μg/kg3,400,00010,000,000100,000355167.5099.90
Acenaphthylene μg/kgNANANA1338186.70
Anthracene μg/kg10,000,0001,000,000100,000828292.50234.67
Benzo[a]anthracene μg/kg9004,000500,0001,4804901,152
Benzo[a]pyrene μg/kg660660100,0001,2405001,009.67
Benzo[b]fluroanthene μg/kg9004,00050,0001,770625916.67
benzo[ghi]perylene μg/kgNANANA288125.25646.67
benzo[k]fluroanthene μg/kg9004,000500,0001,5005701,061
Chrysene μg/kg9,00040,000500,0001,620592.501,361
Dibenz[ah]anthracene μg/kg660660100,000146490665
Fluoranthene μg/kg2,300,00010,000,000100,0003,930997.50873
Fluorene μg/kg2,300,00010,000,000100,000448157.50100.37
Indeno[1,2,3cd]pyrene μg/kg9004,000500,000265104.25851.67
Phenanthrene μg/kgNANANA2,310640661
Pyrene μg/kg1,700,00010,000,000100,0003,1009252,676.67
dieldrin μg/kg4218050,0006.884.550.59
4,4′-DDD μg/kg3,00012,00050,0008.204.451.47
4,4′-DDD μg/kg2,0009,00050,000127.652.83
4,4′-DDD μg/kg2,0009,000500,00020.2513.553.30
Aroclor 1242 μg/kg4902,00050,0002951953.20
Aroclor 1254 μg/kg4902,00050,000315247.5083.47
Aroclor 1260 μg/kg4902,00050,000238129.254.80
2,3,7,8-TCDD pg/gNANANA7.057.754.77
TEQ dioxin pg/gNANANA38.3033.0823.85
Table Table 2.. Summary of leachability results of stabilized dredged material (SDM)ab
  Laboratory MEP (N = 4)MEP (N = 3)PreconstructionPost
 Groundwater Criteriahighest extractlast extractfirst extract123
  1. aMultiple Extraction Procedure (MEP) was performed on both laboratory-prepared SDM and stockpiled SDM, with the highest value of all samples reported for each category. Percolated water was collected from the embankment leachate collection system. Sample numbers are for sequential samples from July 1999 to August 2000. Bold numbers indicate an exceedance of water quality criteria. Numbers in parentheses indicate detection limit for nondetected compounds.

  2. b TEQ = 2,3,7,8-TCDD Toxicity Equivalents; NA = not available; Ag = silver; As = arsenic; Ba = barium; Cd = cadmium; Cu = copper; Hg = mercury; Mn = manganese; Ni = nickel; Pb = lead; Se = selenium; Zn = zinc.

Ag μg/L30.00(1.9)(0.65)(8.9)25.0024.0023.00
As μg/L8.007.307.3031.00(6.7)(6.7)30.00
Ba μg/L2,000.0081.4070.6020.00270.00200.0080.00
Cd μg/L4.00(0.15)(0.15)(3.3)1.00(3.3)(1.1)
Cu μg/L1,000.0097.2030.80270.0047.0058.0013.00
Hg μg/L2.006.100.980.04(0.05)0.18(0.05)
Mn μg/L50.00(0.4)(0.1)(11)3,400.001,770.00950.00
Ni μg/L100.0037.802.4077.00120.00220.0065.00
Pb μg/L10.001.10(0.9)(2.2)15.0019.00(1.4)
Se μg/L50.003.203.204.00(5.6)(5.6)(2)
Zn μg/L5,000.0017.8012.0075.00190.00160.0024.00
TEQ (pg/L)NA3.953.32NA3.902.60(11)
Table Table 3.. Summary of analysis of stormwater runoff during and following construction (post capping)ae. Numbers in parentheses indicate analytical detection limits
  Runoff water samples
  During constructionAfter construction
 SE/SC WQC (μg/L)1c1d2c2d3c3d4d5d6d7d
  1. a Bold numbers indicate an exceedance of water quality criteria at the edge of the embankment. Sample numbers indicate sequential samples taken between Sept. 1999 and Dec. 2000. All samples reported on a total sample basis.

  2. b NY/NJ Harbor Estuary chronic criteria

  3. c Berm 1.

  4. d Berm 2.

  5. e TEQ = 2,3,7,8-TCDD Toxicity Equivalents; SE/SC WQC = NJDEP Saline surface water quality criteria; Ag = silver; As = arsenic; Ba = barium; Cd = cadmium; Cu = copper; Hg = mercury; Mn = manganese; Ni = nickel; Pb = lead; Se = selenium; Zn = zinc; NA = not applicable.

Ag μg/LNA16.00(8.9)(8.9)(8.9)(8.9)(8.9)9.00(2.1)6.30(2.1)
As μg/L0.141,330.00550.00180.00590.00230.00610.006.70(3.8)9.3010.00
Ba μg/LNA480.00220.0025.00100.0037.0088.0092.0059.0059.0039.00
Cd μg/LNA11.004.00(3.3)(3.3)(3.3)(3.3)3.30(1.1)(1.1)(1.1)
Hg μg/L0.150.490.450.090.200.030.010.270.060.020.08
Mn μg/L100.00990.00560.0051.00200.0027.0046.00180.0059.0063.0021.00
Ni μg/L3,900.00430.0089.0033.0098.0048.0088.0041.008.007.203.00
Pb μg/L24.00670.00240.0011.0083.00(2.2)16.0030.003.001.20(1.4)
Se μg/LNA39.0021.008.005.005.0014.005.60(2)(2)(2)
Cu μg/L5.6b1,170.00390.00170.00330.00270.00400.00120.0043.0051.0036.00
Zn μg/LNA610.00400.00(11)(11)28.00(11)150.0034.0050.0032.00
TEQ (pg/L)NA2.60(9.1)(8.4)(12)(11)(7.1)(3.6)(6.5)(8.4)(3.9)
Table Table 4.. Results of area air sampling of particulate and vapor phases during construction of embankmentsa
Chemical (ng/m3)Particulate matterVapor
 UpwindWownwindCrosswindUpwindDownwind
  1. a Ag = silver; As = arsenic; Ba = barium; Cd = cadmium; Co = cobalt; Cr = chromium; Cu = copper; Hg = mercury; Mn = manganese; Ni = nickel; Pb = lead; Se = selenium; Zn = zinc; DDE = dichlorodiphenyldichloroethylene; NA = not applicable.

Ag0.2–2.70.1–2.10.4–1.8NANA
As0.7–15.71.2–8.63.1–18.5NANA
Ba0.2–204.522.0–120.540.0–346.4NANA
Cd0.1–2.90.4–1.80.5–4.2NANA
Co0.7–8.11.3–6.72.2–16.6NANA
Cr2.6–29.84.3–48.511.8–90.1NANA
Cu219.6–53072.7–771.174–435.1NANA
Hg3.2–3.71.6–1.9NDNANA
Mn15.4–221.423.9–279.369.4–238.2NANA
Ni8.5–48.212.5–33.814.3–68.8NANA
Pb9.6–149.125.8–126.639.1–528.4NANA
Se0.1–3.40.7–3.11.5–2.2NANA
Zn105.4–710.3186.8–448.2104.2–653.3NANA
Acenaphthene0.03–0.080.01–0.04NDNDND
Acenaphthylene0.09–0.240.04–0.05NDNDND
Anthracene0.02–0.230.03–0.120.03–0.490.57–3.160.37–1.56
Benzo[a]anthracene0.05–1.00.08–0.300.10–2.160.02–0.040.02–0.09
Benzo[a]pyrene0.04–0.850.08–0.250.08–1.910.030.01–0.09
Benzo[b]fluroanthene0.16–1.240.22–0.750.03–0.480.040.01–0.15
Benzo[ghi]perylene0.12–0.660.14–0.270.16–2.660.020.06
Benzo[k]fluroanthene0.16–1.240.22–0.750.03–0.480.040.01–0.15
Chrysene0.10–1.350.12–0.420.16–2.330.11–0.130.12–0.20
Dibenz[ah]anthracene0.001–0.180.005–0.040.008–0.5380.0020.001–0.01
Fluoranthene0.08–1.740.17–0.800.18–2.784.36–5.993.54–6.94
Fluorene0.01–0.090.01–0.110.01–0.150.66–6.832.26–9.46
Indeno[1,2,3cd]pyrene0.01–0.950.10–0.280.12–2.780.01–0.050.01–0.14
Phenanthrene0.11–1.090.11–0.600.04–1.689.24–26.7214.01–42.04
Pyrene0.10–1.390.14–0.550.16–2.402–3.282.07–3.87
4,4′-DDE0.49–0.690.22–0.380.25–11.4553–10057–64
2,4′-DDE0.55–1.110.38–2.50.46–7.6713–2914–24
4,4′-DDT0.95–1.541.42–3.890.91–29.75.8–13.811–6.7
Sum PCB0.092–31.60.13–22.3325.87–513.313,023–2,8583,638–5,567
Total particulate matter mg/m30.1–0.470.1–0.330.2–1.16NANA
Respirable particulate mg/m30.1–0.490.03–0.11NMNANA

Groundwater impacts

No volatiles, semivolatiles, or pesticides were detected at concentrations exceeding NJDEP-specified detection limits (NJDEP 1977). However, some metals (As, Mn, Ni, and Pb) were observed at concentrations exceeding criteria in some of the field samples, and Hg exceeded criteria in laboratory-prepared leachate (1 MEP extract only). In general, the concentrations in all metals decreased following successive MEP extracts. Leachate from stockpiled SDM was cleaner than that observed during construction, with only As being above applicable criteria in all samples (1st extract only). This may be indicative of sampling variability or possibly contamination at the sampling locations for the percolated water because of windblown dusts. The fugitive air emissions showed elevated concentrations of Ba, Mn, Ni, Pb, and Zn (see Table 4), the same constituents elevated in the percolated water samples. The percolated water samples were taken at the bottom edge of the embankment with an assumption made that there were no dispersive or confining layers. Given that the site has both a layer of waste and a layer of meadow mat, the observations can be considered to be worst case. Using the highest observed concentrations and taking into account dispersion and retardation due to sorption and ion exchange, it was shown that groundwater discharge from the SDM was 1 to 2 orders of magnitude lower than that necessary to affect groundwater quality of the underlying aquifer. In practice, SDM embankments would have a much deeper cap on the side slopes and a top of impermeable macadam, further restricting the flow of water into the berm and limiting the generation of leachate. However, the fact that there are any exceedances of criteria supports the current policy to restrict SDM use to areas remote from drinking water aquifers and to those areas already considered impacted.

Air quality impacts

The data collected in this study indicate that although there appears to be a potential for release of contaminants in both the particulate and the vapor phase, placement or use of SDM does not have the potential to substantially decrease air quality in the region. Upwind and downwind samples typically were within the same order of magnitude and highly variable, making it difficult to definitively assign a source to the readings. In almost all cases, the range of concentrations observed upwind was greater than that observed downwind. The highest concentrations for all particulate-bound contaminants detected were observed in the crosswind samples. Field notes indicate that this corresponds to a particularly high wind event blowing dust from adjacent industrial and construction activities.

The vapor-phase readings appear to show some slight increase in contaminant loading across the SDM placement area, particularly for PCBs. Although these concentrations are well below applicable air quality criteria, there appears to be some potential for release of semivolatile organic contaminants from SDM. This observation has prompted additional field and laboratory evaluations to quantify the potential for semivolatile organic and mercury volatilization during processing and placement of SDM.

Personal air quality monitoring devices also showed that although the workers were breathing particles and particle-associated contaminants, the concentrations were well below that considered to be a danger to health according to NIOSH, OSHA, or the American Conference of Industrial Hygienists (ACGIH). However, because of the lack of published exposure limits for PCBs and PAHs and the highly variable nature of sediment contamination in NY/NJ Harbor, it is recommended that workers wear personal protective equipment to avoid ingestion of dust particles from SDM. In addition, site managers should employ best management practices to reduce the amount of airborne dust at sites processing and placing SDM.

CONCLUSIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

There were no indications of short- or long-term environmental harm caused by the use of this SDM at the Elizabeth site. In this case, the industrial location with existing unremediated contamination, engineering controls to prevent off-site migration of contaminants, and the intended future use as a commercial or industrial site all combined, to produce a situation with minimal environmental sensitivity. Although contaminants from the SDM in both stormwater and leachate in this study were well below the levels of concern for the Elizabeth site, other locations or other sources of sediment might well have resulted in different conclusions. The known variability of sediment contamination in NY/NJ Harbor, coupled with the variability in site conditions across the state, make it impossible to make a generic recommendation regarding the environmental safety of SDM in roadway applications. Rather, the use of SDM should continue to be considered and permitted on a case-by-case basis, both from the source side and the placement side. Essentially, SDM should continue to be placed only on historically contaminated sites with either engineering or institutional controls to prevent unintentional release of, or exposure to, contaminants.

The greatest potential for release of contaminants occurs during construction. For those locations deemed appropriate for the use of SDM, reduction in potential contaminant release can be achieved by ensuring that best management practices be employed with regard to stormwater management, fugitive dust, and erosion control. SDM should not be allowed to remain stockpiled without artificial or natural cover for long periods of time because of increased potential for fugitive and erosional losses. Given that stockpiling and reexcavation reduces the achievable strength of SDM (Maher et al. 2004), it becomes economically prudent, as well as environmentally beneficial, to place the material in its final location as soon as practical.

No violations of published industrial hygiene thresholds for either particulate- or vapor-phase contaminants were observed. However, the fact that concentrations were seen to be above background and particulates were largely of a respirable size, as well as the largely unknown potential effects of other contaminants without hygiene limits (such as PCBs and PAHs), indicate that care should be taken to protect workers from dust. In addition, site managers should take steps to reduce the generation of dust from construction activities.

Project managers should consider all implications of the use of SDM in their projects. Geotechnical, cost, constructability, and availability are all important issues to be considered for the use of SDM in highway construction that are beyond the scope of this article. Whereas the environmental impacts from the use of SDM are either nonexistent or can be lessened through engineering controls or best management practices, the potential public relations issues must be considered. Those areas most likely to benefit from navigational dredging projects (ports and other maritime dependent industries) should be preferentially chosen for potential SDM use because these communities are least likely to object to its use as construction fill.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References

This project was managed by the New Jersey Department of Transportation and funded through a grant from The Port Authority of New York and New Jersey.

References

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONCLUSIONS
  8. Acknowledgements
  9. References
  • Douglas WS, Baier LJ, Gimello RJ, Lodge J. 2003. A comprehensive strategy for managing contaminated dredged material in the Port of NY and NJ. Journal of Dredging Engineering 5 (3): 112.
  • Maher A, Bennert T, Jafari F, Douglas WS, Gucunski N. 2004. Geotechnical properties of stabilized dredged material (SDM) from the New York/New Jersey Harbor. In: Transportation Research Record No. 1874. Washington DC: Transportation Research Board, National Research Council. p 8696.
  • Maher A, Douglas WS, Jafari F, Bennert T. 2005. Use of stabilized dredged material (SDM) from the New York/New Jersey Harbor in the construction of roadway embankments. Journal of Solid Waste Technology and Management (forthcoming).
  • McDonough FM, Boehm GA, Douglas WS. 1999. Dredged material management in New Jersey: A multifaceted approach for meeting statewide dredging needs in the 21st century. In: Proceedings of the 31st Annual Dredging Seminar, Western Dredging Association; 1999 May 15–18; College Station, TX. College Station (TX), USA: Center for Dredging Studies.
  • [NJDEP] New Jersey Department of Environmental Protection. 1997. The management and regulation of dredging activities and dredged material in New Jersey's tidal waters. Trenton (NJ), USA.
  • Sadat Associates. 2001. Use of dredged materials for the construction of roadway embankments. Princeton (NJ), USA.
  • [USEPA] U.S. Environmental Protection Agency. 1983. APTI course 435—Atmospheric Sampling. Research Triangle Park (MD). EPA 450/2–80–005.