background and statement of problem

Su

Date: July 29, 2009 From:

Ric McCulloch, John Wolfe and Dan Lautenbach (LTI) Clay Patmont and Paul LaRosa (Anchor QEA)

To: Todd Konechne and Steve Lucas (Dow Chemical)

cc: Marty Crook (URS Corporation) Peter Simon and Philip Simon (ATS, Inc.)

Subject: Evaluation of Tittabawassee River Reach D Main Channel Natural Deposition Cap

Background and Statement of Problem This technical memorandum presents an evaluation of monitoring data and modeling results for the Tittabawassee River H-13 Reach D Project Main Channel area (Site), portions of which currently contain elevated surface sediment concentrations of ortho-phenylphenol (OPP). This memorandum assesses the likelihood that an effective sediment cap will accrete naturally upon removal of the temporary sheet piling, which would then be verified through periodic bathymetric surveys and adaptive management to confirm the formation and effectiveness of the natural cap. This document supplements the Interim Response Action (IRA) Work Plan (URS, 2008) previously submitted to the Michigan Department of Environmental Quality (MDEQ), which presented the basis of design for an in situ cap to contain residual contaminated sediments remaining following dredging (in 2007 and early 2008) within the nearshore sheet pile enclosure along the eastern shore of Reach D. The Reach D cap (inside the sheet pile wall) is currently under construction. Bathymetric surveys of the Reach D riverbed performed in spring 2009 identified two scour areas adjacent to sections of in-river sheet pile that had been installed in 2007. Comparisons to 2007 bathymetry showed that these features had developed between 2007 and 2009. Sediment sampling in Reach D in 2008 and 2009 indicated that elevated OPP concentrations were present at the sediment surface in the deeper portions of the more downstream of the two scour areas. Elevated surficial sediment OPP concentrations exceeding the site-specific no-effect bioassay benchmark of approximately 0.1 milligrams per kilogram (mg/kg; Sorensen et al. 2009) were identified in samples RD-54+75-IC-C3, RD-54+75-IC-C1, RD-55+30-IC-C1, and RD-55+75-IC-C1, where the 2009 sediment surface was 4 feet or more below the 2007 riverbed. However, even Site sediment in the downstream scour area containing the highest OPP concentrations (92 mg/kg) exhibited only minor biological effects (19 percent reduction in survival relative to matched reference sediment), which may not be biologically significant. Elevated surface sediment OPP concentrations were not identified in the upstream scour area. Installation of the sheet pile enclosure and follow-on sediment removal operations at the Site were performed under the July 12, 2007 Administrative Settlement Agreement and Order on Consent for Removal Action between MDEQ and the Dow Chemical Company (Dow). The sheet pile wall specified for the project encompassed the entire sediment Reach D removal area along the eastern shoreline just

Evaluation of Tittabawassee River Reach D Main Channel Natural Deposition Cap page 2

upstream of the Dow Dam, and tied back into shore at the northern and southern boundaries of the dredging area. Sediment removal activities were completed at the Site in 2007. As discussed in Lautenbach et al. (2009), bathymetric monitoring data and hydrodynamic modeling results revealed that installation of the sheet pile quickly and markedly increased shear stresses in a localized area adjacent to the sheet pile, resulting in erosion of up to approximately 12 feet of sandy sediments that were previously present in this area. Erosion in these areas is attributable to the sudden narrowing of the river due to the temporary sheet piling, resulting in increased turbulent river flow velocities, markedly increasing average annual peak shear stresses in localized areas adjacent to the sheet pile (from less than 50 dynes/cm2 to greater than 100 dynes/cm2), sufficient to mobilize gravel-sized and finer particles. The sheet pile-induced sediment erosion removed the natural sediments (effectively a natural sediment cap) that had previously deposited over time in Reach D (accretion likely occurred shortly after construction of the downstream Dow Dam), exposing previously buried contaminated sediments with relatively elevated OPP concentrations. While shear stresses are anticipated to return to baseline levels following removal of the temporary sheet pile in fall 2009, resulting in accretion of incoming clean sediments within the depression and eventual reestablishment of the natural cap, further analysis was necessary to estimate the time required to form a similarly protective cap. This further analysis is presented herein. Baseline (i.e., prior to sheet pile installation) sediment conditions in the general OPP deposit area of Reach D were characterized in 5 cores (i.e., cores RD-53+75-IC-C1 [IC126], RD-53+75-IC-C2 [IC200], RD-54+75-IC-C2 [IC114], RD-54+75-IC-C3 [IC147], and RD-55+50-IC-C1 [IC127]). These 5 cores were advanced in areas immediately adjacent to the newly-exposed downstream scour area (but generally unaffected by the recent erosion) and are representative of sediment conditions that existed in the erosion area prior to installation of the sheet pile. At depths between approximately 15 and 20 feet below current riverbed, these sediments contained subsurface maximum OPP concentration of more than 100 mg/kg (Figure 1). However, the surface sediment (0 to 1 feet below current riverbed) OPP concentration in these baseline cores was less than 0.1 mg/kg. Thus, the site characterization data reveal that, prior to sheet pile installation and resultant sediment erosion, the natural sediment cap that had deposited over time in Reach D provided protective containment of underlying contaminated sediments. As summarized in EPA (2006), while OPP is stable and persistent in abiotic media, it is photolytically unstable and degrades completely in 14 days when exposed to sunlight, degrading into phenyl benzoquinone, phenylhydroquinone, and 2-hydroxybenzofuran. EPA (2006) reported that based on its high Koc, it is relatively immobile in soils and is not likely to migrate through groundwater or sediment porewater. In a setting such as Reach D, the major degradation pathway for OPP appears to be through biodegradation. This information, as well as the vertical distribution of sediment OPP concentrations in Reach D sediment (Figure 1), indicates that OPP is likely stable within subsurface Reach D sediments, with little potential for groundwater or surface water transport. Calculations using the EPA’s transient cap model (Palermo et al. 1998 a&b), as updated by Reible et al. (2004), indicate that sedimentation rates on the order of roughly 0.5 feet per year over a period of 1-2 years will likely sufficiently reduce sediment toxicity effects by maintaining surficial sediment OPP concentrations below 0.1 mg/kg.


0

5

10

15

20

25

30

0.01 0.1 1 10 100

Dep

th Below

Mud

line (ft)

Sediment Orthophenylphenol Concentration (mg/kg)

Figure 1. Baseline Reach D Average Sediment OPP Concentration Profile (solid line is the mean from 5 representative baseline cores; dashed line is ± 1 std. dev.)

The objective of this memorandum is to use existing data and available models to evaluate the likelihood that natural accretion rates in this range will occur in the deepest portions of the two scour areas, once the temporary sheet piling is removed. The findings will support an evaluation whether residual OPP concentrations in Reach D might be adequately addressed during reestablishment of the “natural cap”. As discussed above, it is anticipated that such an approach could involve periodic bathymetric surveys, and adaptive management to confirm the reformation and effectiveness of the natural cap.

Summary of Findings Based on the finding described in this technical memorandum, it is likely that sediments will accrete due to bed load transport to the Reach D scour areas, so that they will likely accrete to a minimum thickness of 0.5 feet during the first year in the areas of deepest scour. During relatively high flow events, some filling will occur over the entirety of the scour areas, but not in an even manner. Most accretion will occur in the deepest portions of the scour areas, which correspond to the areas with the lowest existing bed load flux. Much of the remaining accretion is anticipated to occur upstream of those deepest areas. The least accretion will likely occur downstream of the deepest areas, because so much of the bed load will be captured by those areas, rather than passing through them. Estimates of accretion for the two


scour areas were made using two scenarios for allocating accreting sediments within each scour area, as described below:

1. Scour areas fill at deepest locations first (less conservative):

- In other words, new sediment delivered to the scour areas is assumed to first fill the area of the deepest 0.5 feet of scour, then the area of the next deepest 0.5 feet of scour, and so on. In reality, some accretion will occur in other portions of the scour areas as well.

2. Accretion is uniform across the upstream half of each scour area, including the area of deepest

scour (more conservative):

- Accretion is expected to be greater upstream of the deepest scour areas than downstream of the deepest areas. In this scenario, the new sediment delivered to the scour area is assumed to increase the elevation everywhere from the deepest portion of the scour area to the upstream edge of the scour area by the same number of inches. Accretion at the deepest portion of the scour areas is not assumed to be any more rapid than accretion upstream of those deepest areas. Because accretion should be more rapid in the deepest portion of the scour areas, this accretion estimate is conservatively low.

Using the less conservative assumption (1), the deepest portion of the upstream scour area is predicted to net fill by 2 feet or more per year under observed flows and predicted bed load in each of the past water years (October 1 – September 30; i.e., assuming filling from deepest to shallowest). For the downstream scour area, net filling to 1 ft/yr or more is predicted using observed flows and predicted bed load during 99 percent of past water years, and to 2 feet or more per year in 92 percent of past water years, again assuming filling from deepest to shallowest. Using the more conservative method of estimating uniform accretion over half of each scour area, including its deepest portion (2), that part of the upstream scour area is predicted to fill at a rate of 0.5 ft/yr under observed flows and predicted bed load in 97 percent of past water years and 1 ft/yr in 90 percent of past water years. For the downstream area, filling is predicted at 0.5 ft/yr under observed flows and predicted bed load in 82 percent of past water years and 1 ft/yr in 78 percent of past water years. These estimates are based on the methods described below.

Methods To estimate sediment bed accretion we simulated Reach D bed load, with 2009 bathymetry, and a new Reach D cap in place. Reach D includes two scour areas, defined as areas greater than three feet of scour, shown in Figures 2 and 3. Figure 2 delineates the area of largest scour in the upstream portion of Reach D and Figure 3 delineates the area of largest scour in the downstream area of Reach D, based on comparisons of the 2007 and 2009 Reach D bathymetric data sets. The yellow line on both figures outlines the area containing at least three feet of measured scour. The colored areas within the yellow outline detail the areas of deepest scour in 0.5 foot increments. An in-channel Environmental Fluid Dynamics Code (EFDC) model, extending from a short distance upstream of the confluence of the Tittabawassee and Chippewa Rivers down to the U.S. Geological Survey (USGS) gage downstream of the Dow Dam, was developed for use in a variety of investigations, including this analysis. The EFDC model grid used for this evaluation is shown on Figures 2 and 3. A detailed summary of the initial model development is described in the memorandum “Results and Implications of 2-D Curvilinear Modeling of the Upper Tittabawassee River” (Lautenbach et.al. 2009).


Figure 2: Upper Reach D Scour Area, to a Depth of at Least Three Feet, With Areas of Greatest Scour Delineated


Figure 3: Lower Reach D Scour Area, to a Depth of at Least Three Feet, With Areas of Greatest Scour Delineated


The method for estimating bed load at each transect shown in Figures 2 and 3 is described below. Shear stresses were estimated for each transect for a series of flow conditions, using the EFDC model. Using these results, available local sediment grain size data (assuming 600 micron particles, a conservatively high representation of average grain size measured at the reach), and the van Rijn bed load formulation (van Rijn, 1984), a relationship was established for each transect relating bed load to flow. Van Rijn’s method to calculate bed load is a well accepted, standard method of calculating bed load that was based on much of the available field and laboratory bed load data accumulated over decades. A bed load transport rate can be computed as the product of the particle saltation (i.e., jump) height, particle velocity, and bed load concentration for a sediment size of interest. Van Rijn’s method, which estimates bed load transport by relating each of these factors to known sediment and hydrodynamic information, was verified using about 600 experimental bed load transport measurements, and was accurate within a factor of two. Bed load-flow relationships based on the van Rijn formulation make it possible to estimate daily bed load accretion in the deepest portion of each scour area for any given daily flow. The relationships predict that much of the net accretion due to bed load will occur during the highest flows. To estimate the future probability of accretion at target rates, the approach was to simulate bed load for one-year periods using daily flows for the period of record (1937-2008) and calculate the percentage of years during which target accretion depths would have been met. To compute depths of accretion from deepest to shallowest, scour volumes were computed to each scour depth using GIS and compared to estimates of delivered bed load volumes (scenario 1, above). To compute accretion rates over given areas of interest, volumetric bed load rates per year were divided by half of each scour area, including the part with deepest scour (scenario 2, above). For the upstream scour area, accretion was estimated as the difference between bed load fluxes crossing two transects, one located just upstream of the area (labeled “upstream” in Figure 2) and one located across the center of the scour area (T1). Accretion in the downstream scour area was estimated as the difference between bed load not captured by the upstream scour area (i.e. bed load at T1), and bed load across a transect at the center of the downstream scour area (T2).

Results Table 1 shows the estimated bed load flux across each transect for the flow rates simulated, ranging from 1,000 cfs to 22,000 cubic feet per second (cfs). Simulated bed load fluxes are negligible below about 5,000 cfs and increase as a function of flow. Figures 4 and 5 show that this increase is approximately linear, beyond a threshold of about 5,000 cfs, so that estimated bed load fluxes for the larger events simulated are much larger than for more frequent lower-flow events.

Table 1. Estimated Bed Load Fluxes at Simulated Flow Rates

Upstream T1 T21,000 0 0 03,000 8 0 05,000 80 6 07,000 242 34 212,000 577 150 3517,000 751 261 8022,000 985 403 135

Flow (ft3/s)

Bedload (MT/day)


-50

100150200250300350400450500

0 5,000 10,000 15,000 20,000 25,000

Flow (ft3/s)

Bed

load

Flu

x (g

/m/s

)Upstream T1 (within A1)

Figure 4: Simulated Bed Load Fluxes across Two Transects (Upstream and T1)

-50

100150200250300350400450

0 5,000 10,000 15,000 20,000 25,000

Flow (ft3/s)

Bed

load

Flu

x (g

/m/s

)

T1 (within A1) T2 (within A2)

Figure 5: Simulated Bed Load Fluxes across Two Transects (T1 andT2)

g f 1.6 g/cm3 (assuming a particle density of 2.65 g/cm3 and porosity of 0.4, typical of

sandy sediments).

From Figures 4 and 5 it can also be seen that the difference in bed load flux between paired transects is a strongly increasing function of flow. Table 2 presents those differences as volumes, representing rates of increase in bedded sediment volume. The conversion from mass rates to volumetric rates was made usina dry bulk density o


Table 2. Volumetric Difference in Bed Load Between Transects (Bedded Volume)

r arget accretion rates in a year,

iven the range of flows that can expected over the course of a full year.

ch were

th of

st

as

ered than the minimum required, indicating that larger thicknesses of accretion

ould have occurred.

expected in most water years in the pstream half of each scour area, including the deepest portions.

rs delivering much more sediment than is needed to net fill those portions to a depth of 0.5 feet per year.

22,000 366 169

(US - T1) (T1 - T2)Delta BL (m3/day)

Delta BL (m3/day)

1,000 0 03,000 5 05,000 47 47,000 131 20

12,000 268 7217,000 308 114

Flow (ft3/s)

Interpolating between the flows represented in Table 2, these relationships between flow and bed loadwere used to simulate rates of accretion, assuming 2009 post-construction bathymetry, for flow rates recorded every day of the period of record 1937-2008. Daily rates were accumulated over complete wateyears (October 1 – September 30) to indicate the frequency of achieving tg Figures 6 and 7 show the distributions of computed volumes, across water years, simulated to accumulate in upstream and downstream scour areas. This was compared to estimated scoured volumes, whibased on a comparison of 2007 and 2009 bathymetry. The latter estimates showed that very little accretion was needed to net fill the deepest scour areas from the lowest elevation to the minimum dep0.5 feet required. In the upstream scour area a volume of six cubic meters was needed to net fill thelowest one foot of scour area, and under the assumption that scour areas fill from lowest to higheelevation, this would have been achieved for every water year over the period of record. In the downstream scour area, a volume of six cubic meters was also required to net fill the lowest one foot of scour area, and under the assumption that scour areas fill from lowest to highest elevation, this accretion volume would have been achieved in 99 percent of the water years in the period of record. Tables 3 and 4show the volumes of fill required to achieve various minimum depths of fill at each scour area as well the percentage of years in which this minimum volume would have been delivered. A comparison of Figures 6 and 7 with Tables 3 and 4 shows that for most water years, a much larger volume of materialwould have been delivw Figures 8 and 9 show the distributions of accretion rates, across simulated water years, under the moreconservative assumption that accretion is uniform across the upstream half of each scour area. They show that accretion at rates greatly exceeding 0.5 feet per year areu The distributions of accretion rates across simulated water years are also shown for each scour area inTables 5 and 6. These tables also show that accretion at rates greatly exceeding 0.5 feet per year are expected in most water years in the upstream half of each scour area, including the deepest portions, with most water yea


.

Figure 6: Distribution of Annual Fill Volumes in Upstream Scour Area (A1), Using Flows from Water Years 1937-2008

Figure 7: Distribution of Annual Fill Volumes in Downstream Scour Area (A2), Using Flows from

Water Years 1937-2008


Table 3: Depths of Fill, Corresponding Volumes of Fill, and Likelihood of Occurrence in Deepest Portion of Upstream Scour Area (A1), Using Flows from Water Years 1937-2008

Depth of Fill (ft) Volume of Fill (m3) Percentage of Water Years

(1937-2008) Exceeding 1 6 100 2 58 100 3 262 97

Table 4: Depths of Fill, Corresponding Volumes of Fill, and Likelihood of Occurrence in Deepest

Portion of Downstream Scour Area (A2), Using Flows from Water Years 1937-2008

Depth of Fill (ft) Volume of Fill (m3) Percentage of Water Years (1937-2008) Exceeding

1 6 99 2 32 92 3 70 89

Figure 8: Distribution of Annual Deposition Rates for Upstream Scour Area (A1), Using Flows

from Water Years 1937-2008 and Assuming Accretion over Half of Area


Figure 9: Distribution of Annual Deposition Rates for Downstream Scour Area (A2), Using Flows

from Water Years 1937-2008 and Assuming Accretion over Half of Area Table 5: Frequencies of Simulated Deposition Rates for the Upstream Scour Area (A1), Assuming

Filling of the Upstream Half of the Scour Area Including the Deepest Portions

Deposition Rate (ft/yr) over ½ Area, including Deepest Portions Percent of Water Years (1937 – 2008) Exceeding

0.5 97 1 90 2 82

Table 6: Frequencies of Simulated Deposition Rates for the Downstream Scour Area (A2), Assuming Filling of the Upstream Half of the Scour Area Including the Deepest Portions

Deposition Rate (ft/yr) over ½ Area, including

Deepest Portions Percent of Water Years (1937 – 2008) Exceeding

0.5 82 1 78 2 56

As shown above, bed load transport is highly flow-dependent, and high flows are most common in the spring on the Tittabawassee River and least common in late summer. Consequently, bed accretion as simulated is very unlikely to be uniform across the calendar year; instead, it is likely to occur during the largest spring events and very unlikely to occur during low-flow periods. Figures 10 and 11 below illustrate this based on August and March daily flow records for the water years 1937-2008. A comparison of Figure 10 to Figure 6 shows that a significant fraction of annual bed load volume (in this case the volume delivered to the upstream scour area) can be expected to occur during the month of March when flows are historically high. In contrast, Figure 11 shows that very little bed load can be


expected to be delivered during the month of August when flows are historically low. For this reason, any evaluation of bathymetric monitoring of the Reach D scour areas should take into account seasonality and the observed frequency of intervening high-flow events. In years when flows are lower than normal, taking into account normal seasonal patterns, accretion rates at the lower end of the distributions shown above should be expected, and vice versa in years when flows are high relative to normal seasonal patterns. Conducting bathymetric verification monitoring at the same time every year is advisable, given the expected seasonality of accretion.

Figure 10: Distribution of March Fill Volumes in Deepest Portion of Upstream Scour Area (A1), Using Flows from Water Years 1937-2008

Figure 11: Distribution of August Fill Volumes in Deepest Portion of Upstream Scour Area (A1), Using Flows from Water Years 1937-2008


Comparison to Existing Field Data The relationship between flow and bed load, developed using the EFDC model and the van Rijn bed load formulation, was checked for the most upstream transect against available bed load data, which provided confirmation of predicted bed load volumes for flows up to about 6,000 cfs. The bed load fluxes measured in June 2008 are consistent with those shown in Table 1. On June 10, 2008, at a flow rate of 6,200 cfs, the measured bed load flux for the combined Tittabawassee (upstream of the Chippewa) and Chippewa Rivers was 235 MT/day. This measured value is slightly smaller than the value simulated for that transect at 7,000 cfs, as shown in Table 11. Bed load was also measured on June 11 and 13, 2008, at flow rates of 4,600 cfs and 3,100 cfs, respectively. The measured fluxes were 16 MT/day on June 11 and 14 MT/day on June 13. These values fall between the 3,000 and 5,000 cfs results for the upstream transect in Table 1. Both measured and computed fluxes rapidly approach a negligible value at the Upstream transect as flow rates fall below 5,000 cfs. For further confirmation, bathymetric comparisons between spring 2007 and spring 2008 were made for Reach O, where installation and removal of sheet pile also occurred. The results support the assumptions made in the Reach D analysis, namely that accretion is greatest in the deepest spots (which are located in approximately the center of Reach O), and that the thickest accretion also tends to occur in the upstream portion of the area. These patterns of accretion can be seen in Figure 12. Limitations of Analysis and Assessment of Findings The following limitations should be recognized with respect to the above analysis and the assumptions on which it is based:

• The bed load calculations performed attribute a specific fraction (50 percent) of total bed stress to grain stress, allotting the remainder to form drag, which does not contribute to bed load transport. This is an approximation of the actual split between grain stress and form drag, which is unknown and variable in time and space;

• van Rijn suggests that his representation of bed load transport is accurate within a factor of about 2;

• The analysis assumes a single grain size grain size (600 µm), whereas the actual bed includes a distribution of sizes; and

• Predicted accretion rates in this analysis are based on expected bed load fluxes over a range of flows using 2009 bathymetry. The accretion rates at the upstream area will slow as it fills over time. More bed load will become available to the downstream area as the upstream area fills, so its rate of filling may either increase or decrease with time. For these reasons, and because of the dependence of bed load on the frequency of high-flow events, fill rates should not be expected to be constant from one year to the next.

Associated uncertainties in simulated bed load would be most important above about 6,000 cfs, because the model-data comparison presented above showed a good match between data and simulated values at the upstream end of Reach D for flows up to 6,000 cfs. No comparable verification data are available for the bed load within the scour areas.

1 The Upstream transect spans roughly ¼ of the total river width, within the region of highest shear stress, and therefore, the region of highest bed load. While the measured bed load reflects an estimate for the full river width, the majority of the 235 MT/day bed load measured on June 10, 2008 came from one sampling location near the center of the river.


Figure 12: Bathymetric Changes in Center of Reach O between November 2007 and Spring of 2008


The estimates presented above of the time required to reform a protective cap in the Reach D Project Main Channel area are conservative in the following regards:

• The accretion estimates are based on simulated bed load only, with no consideration of suspended load transport and net deposition, which for fine to medium sands could be significant at higher flows;

• The assumed grain size of 600 µm is at the upper end of the median size range (300 to 600 µm is median size range based on a single 2008 sample at this approximate location). More bed load transport would be predicted at any given flow rate given a smaller particle size; and

• In one of the two accretion assumptions, sediment is assumed to deposit at the same rate at the upstream ends of the scour areas as in their deepest portions, although accretion is likely to be greatest in the deepest portions.

Even given these elements of conservatism, there is clearly a high likelihood of achieving the needed accretion rates (i.e., greater than 0.5 ft/yr) to provide adequate chemical isolation from current surface sediment impacts. These results support the proposal that an effective sediment cap will accrete naturally upon removal of the temporary sheet piling. As discussed above, it is anticipated that such an approach will involve monitoring, possibly including periodic bathymetric surveys, and adaptive management to confirm the formation and effectiveness of the naturally accreting cap.

References EPA, 2006. Ecological Hazard and Environmental Risk Assessment. 2-Phenylphenol and Salts. Case

2575. Report prepared by K.V. Montague, Antimicrobials Division, Office of Pesticide Programs, US EPA, Washington, DC 20460. April 10, 2006.

Lautenbach, D., J. Grush, J. Wolfe. 2009. “Results and Implications of 2-D Curvilinear Modeling of the

Upper Tittabawassee River.” Memorandum. May 29. Palermo, M. R., J. E. Clausner, M. P. Rollings, G. L. Williams, T. E. Myers, T. J. Fredette, and R. E.

Randall, 1998a. Guidance for Subaqueous Dredged Material Capping. Technical Report DOER-1. United States Army Corps of Engineers, Waterways Experiment Station, Vicksburg, Mississippi.

Palermo, M., Maynord, S., Miller, J., and Reible, D. 1998b. Guidance for In-Situ Subaqueous Capping of

Contaminated Sediments, EPA 905-B96-004, Great Lakes National Program Office, Chicago, IL. Reible, D.D., Kiehl-Simpson, C., Marquette, A.. 2004. Modeling Chemical Fate and Transport in

Sediment Caps. Technical Presentation 380-D. New York, NY: American Institute of Chemical Engineers.

van Rijn, L.C. 1984. “Sediment Transport, Part I: Bed Load Transport.” J. Hydraul. Eng., 110(10):1431-

1455. Sorensen, M., D. Haury, and A. Prusak. 2009. Reach D Sediment Toxicity Testing Results.

Memorandum prepared July 15, 2009.

background and statement of problem

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