groundwater/surface water seepage meter sampling and ... · technical memorandum to: revised...

Appendix F

Groundwater/Surface Water Seepage Meter Sampling and Analysis Results

Technical Memorandum To: Revised Feasibility Study Report Appendix – Supplemental Investigation Activities

From: Katrina Marini, Brad Leick, Irvin Mossberger

Subject: Groundwater/Surface Water Seepage Meter Sampling and Analysis Results

Date: July 15, 2015

Project: Spirit Lake Sediment Site

Introduction Seven seepage meters were installed in the fall of 2012 at the Spirit Lake Sediment Site (Site) in the St.

Louis River, Duluth, Minnesota (Figure 1). The seepage meters were installed in accordance with a

Groundwater/Surface Water Flux Meter Sampling and Analysis Plan (SAP) prepared by Barr Engineering

Company (Barr) in August 2012 on behalf of United States Steel Corporation (U. S. Steel).

Acknowledgement of the SAP by the Minnesota Pollution Control Agency (MPCA) was noted in an

email dated October 13, 2012, but no comments were provided (MPCA, 2012). The original version of

this technical memorandum was provided as an appendix to the Feasibility Study (Barr, et al., 2014). This

technical memorandum provides an updated summary of the field activities, data analyses, and

conclusions. Comments from the Minnesota Pollution Control Agency (MPCA, 2015) are also addressed

here.

Seepage meters are used to evaluate the water flow across the sediment/water interface by measuring the

volume of water that flows into or out of the seepage meter bag. The primary objectives of this study were

(1) to evaluate whether advective flow from the subsurface has the potential to transport constituents of

interest (COIs) through sediment to surface water, (2) to provide information on how groundwater/surface

water interaction may affect possible future sediment management alternatives evaluated for the

Feasibility Study, and (3) to evaluate whether gas generation (ebullition) is occurring in sediments at the

Site. The collected data were analyzed in conjunction with other site-specific data, including water levels

in Spirit Lake and nearby piezometers to provide additional support for the analyses.

To: Revised Feasibility Study Report Appendix – Supplemental Investigation Activities From: Katrina Marini, Brad Leick, Irvin Mossberger Subject: Groundwater/Surface Water Flux Meter Sampling and Analysis Results Date: July 15, 2015 Page: 2 Project: Spirit Lake Sediment Site

P:\Duluth\23 MN\69\23691125 St Louis River Duluth Works Sediment\WorkFiles\P_Feasibility Study\FS-Report\2015 Revised FS

Appendices\06_Appendix F_Groundwater-Surface Water Flux Meter Tech Memo\FINAL_Revised_AppxF_GW_SW_Memo_July152015.docx

Methods Seven seepage meters were installed at the locations shown on Figure 2. The following sections describe

their construction, deployment, and operation.

I. Seepage Meter Materials and Construction Each seepage meter was constructed as shown on Figure 3 using the following materials and process

described below:

Plastic 35-gallon drum;

Size-9 solid rubber stopper;

Flex GP70 PVC tubing, clear vinyl tubing, 3/8-inch inside diameter (ID), 9/16-inch outside

diameter (OD), 3/32-inch wall thickness (manufactured by Flex Tubing Products);

Geotech Silicone tubing, size 15, 0.19-inch ID, part # 87050000;

Silicone caulking;

Hose clamps;

1-liter (L) Tedlar® bag; and

Metal rods to mark locations and secure the bags.

The upper third of each plastic 35-gallon drum was cut off for use as a seepage meter. A hole was drilled

through the top of the drum that was large enough to fit a size 9 rubber stopper. The stopper was inserted

into the drilled hole and sealed with silicone caulking. A hole was drilled through the stopper to

accommodate the clear vinyl tubing. Silicone tubing was then connected to the (larger diameter) vinyl

tubing to allow the Tedlar® bag to be attached. Hose clamps were used to secure the silicone tubing to the

Tedlar® bag and to secure the larger plastic tubing to the smaller silicone tubing. The Tedlar® bag was

modified by removing the valve and cutting the ‘T’ off so that the silicone tube would fit directly onto the

fitting. This process was replicated for all seepage meters and bags constructed and used in the

investigation.

II. Seepage Meter Installation Seepage meter installation followed methods outlined in the SAP as closely as possible. One pilot

seepage meter (Pilot) was installed on August 29, 2012 at the location shown on Figure 2, to test the




seepage meter equipment, installation, and data collection process. Data were collected at the Pilot every

2 to 5 days during the testing phase.

Six additional seepage meters were installed on October 12, 2012. The proposed and actual seepage

meter locations, and names of all seepage meters are presented on Figure 2 and Table 1.

The seepage meters were placed at the locations proposed in the SAP, with the exception of seepage

meters WM-121 and WM-120 which were moved from the proposed locations due to water depths

exceeding anticipated conditions. The target installation depth was between 597 and 600 feet above mean

sea level (msl) so that the meters would be accessible by wading while remaining submerged. Both

seepage meters were moved to the southwest, where the meters could be installed at the intended depth

while maintaining safe access. Seepage meter WM-71 was moved closer to shore after the first

measurement was collected, to make data collection safer, because the original location had sediment too

soft to stand or walk in safely.

The seepage meters were installed by submerging and slowly pushing them into the sediment by hand

with a twisting motion to firmly embed them in the sediment. The barrel caps were removed prior to

submersion to allow air to escape, and then reinstalled once the seepage meters were in place and free of

trapped air. Rocks were placed on the tops of the seepage meters to weigh them down to restrict

movement. A Tedlar® bag was secured to each seepage meter with metal rods inserted through the

grommets in the bags and pushed vertically into the sediment. This allowed the bags to float at or just

under the water surface with changing water levels, which helped protect the bags from ripping in high

winds, and the rods projecting above the water surface made the seepage meters more easily located by

field crews.

III. Seepage Meter Operation/Data Collection/Calculations The primary goal for data collection was to measure the volume of water that flowed into or out of each

seepage meter bag. A loss of water from the bag indicates that water flows from surface water into the

sediment. A gain of water indicates that water flows from the sediment to the surface water.

Measurements of water volume at each seepage meter were conducted using the following process:

1. At deployment, 500 milliliters (mL) of distilled water was poured into a 1-liter graduated

cylinder, and then transferred from the graduated cylinder to a Tedlar® bag using a funnel.




2. The bag was carefully submerged with its attachment hose above the water surface to force air

out of the bag. When this was achieved, a small clip was placed on the hose just above its

connection to the bag to seal the bag.

3. Air was removed from the seepage meter hose by submerging the hose, sealing the end with the

technician’s thumb, lifting the sealed end of the hose to allow air bubbles to rise and collect, and

re-submerging the hose before releasing the technician’s thumb from the hose to allow the air to

bubble out of the hose. When all of the air had been removed from the hose, it was held

underwater by a technician.

4. The section of bag hose was submerged and aligned with the hose attached to the seepage meter.

The two hoses were connected underwater and the overlap was reinforced with a clamp.

5. A zip tie was placed around the metal rod marker stake for the seepage meter and loosely looped

around the seepage meter hose. Therefore the bag could move a small amount in conjunction

with wind-driven waves and the seiche, without adding tension to the floating bag.

6. The time of the connection of the bag to the seepage meter and the volume of water in the bag

were recorded in the field log.

7. Technicians returned after a period of time to collect data from the seepage meters, and the bag

was carefully detached from the seepage meter.

8. The bag was emptied into a 100-mL or 1-liter graduated cylinder (depending on approximate

volume), and the volume was measured to the nearest 10 mL. The volume and color of the water,

along with the date and time of observation, were recorded in the field log.

These steps were repeated for each measurement event.

The net groundwater/surface water flux was calculated at each seepage meter for valid data points using

the equations:

;

where: Q is flux, also called volumetric flow [mL/day]. Note: 1 mL = 1 cm3, V is volume [mL], T is time [days], q is seepage velocity [cm/day], and A is surface area of the lakebed encompassed by the seepage meter [cm2].

The seepage meters used in Spirit Lake enclosed lakebed surface areas of approximately 2,570 cm2.




Results Data collection started August 29, 2012 for the Pilot meter and measurements were made at intervals of

two to five days during the pilot test period. Measurements continued at the intervals of 3 to 4 days after

the installation of the remaining six seepage meters was completed on October 12, 2012. The seepage

meters were removed on November 16, 2012, when Spirit Lake began to ice over at some of the meter

locations.

A total of 88 observations/measurements were collected from the seven seepage meters. Some conditions

were observed during data collection that may have produced erroneous flux calculations and include:

broken bags (holes, torn, or ripped from hose);

insufficient equilibration time following installation or reinstallation of a seepage meter;

incomplete connection between the seepage meter and the bag because of air or ice; and

unsealed connection between the seepage meter and the sediment due to seepage meter

movement or warping.

The top of the Pilot seepage meter was frequently above the water level of Spirit Lake because of its

proximity to the shore, which may have allowed air into the hose if suction was broken around the base of

the meter. The tops of seepage meters UC-79 and WM-121 were also occasionally above the water level

of Spirit Lake, but several UC-79 data points were discarded during these periods. Larger (10-L) bags

were tested after the original bag size was found to be nearly empty several times. While the volumetric

change becomes less accurate as the bag becomes nearly empty, the larger bags were harder to work with

and more easily broken during high wind events. Each seepage meter except WM-71 and WM-120 had

broken bags at least once during the data collection season, and neither seepage meter could be measured

safely on October 23, 2012, because of deep water. Seepage meter WM-100 was observed to be slightly

tilted away from shore on November 6, 2012, and was badly warped upon removal. The tilting and

warping cause is unknown. Data were discarded where any of the above conditions were observed. Of

the 88 total measurements, 53 were considered valid and used in flux calculations.

Seepage meter bag water volume measurements were plotted versus time on a single chart to view

temporal patterns (Figure 4). Most readings show decreasing volume in the bag, indicating that the

predominant flow direction is from Spirit Lake into the aquifer(s). An increase of water volume

measured in the bag, which indicates that net groundwater is flowing upward through the sediment,




occurred in only four of 53 readings (7.5%), once at seepage meter UC-79, twice at UC-79a, and once at

WM-100.

Ebullition was not observed at any of the locations during seepage meter installation, monitoring, or

removal.

Discussion The velocity of seepage across the sediment-water boundary was expected to vary spatially across the site

and temporally as the hydraulic gradient changes (Table 2). The flux and velocity calculated from

seepage meter measurements are considered net rates, because the water could flow both into and out of

the bag between measurements as driven by transience in lake level. The water color observed in the

bags was used as a general guide to the source(s) of the water at each measurement because lake water

(and possibly pore water) has a brownish tint in comparison to distilled water which is colorless. The

water in the bag was frequently clear in seepage meters WM-71 and WM-100, and WM-120, but tended

to appear mixed at the Pilot, UC-79, and UC-79A. Water color varied from clear to mixed in the WM-

121 seepage meter. Small biota (freshwater shrimp in appearance) was occasionally observed in the bags

as well.

Seepage meter data were grouped by Site area (i.e., Unnamed Creek, Upper (northern) Wire Mill, and

Wire Mill Delta – as shown on Figure 2) and graphed with total daily precipitation, water levels in nearby

piezometers, and a 12-hour moving average of the water level in Spirit Lake (Figures 5-8) to evaluate

potential changes to other hydrologic processes during the time seepage meter measurements were made.

Precipitation data were collected at the Site weather station. Spirit Lake elevation measurements were

collected at a Site gauge.

Piezometer nests were installed on adjacent shoreland by URS Corp. in 2001 (URS, 2002), and each

consist of three closely-spaced piezometers completed to various depths, with a letter at the end of its

name designating its depth. For example piezometer nest PZ-E-1 consists of three piezometers: PZ-E-1A

(shallow), PZ-E-1B (mid-level), and PZ-E-1C (deep). The piezometers were screened in various

hydrostratigraphic units. Water level elevations from the piezometer nests and Spirit Lake were measured

to evaluate the local groundwater flow pattern from adjacent upland areas to the lake.




The overall trend in the water level of Spirit Lake was a gradual decrease in elevation from the beginning

of September to the middle of October, after which the water level oscillated around the seasonal average

elevation (record period 8/15/2012 – 11/21/2012) of 601.25 feet (ft) msl. The elevations oscillated

between minimums and maximums of approximately 600.25 ft msl to 601.9 ft msl, respectively, during

this period.

The trend in piezometer water levels in the Wire Mill and Upper Wire Mill area was neither increasing

nor decreasing from the beginning of the monitoring period until early November. The water levels

decreased in most of the piezometers for the remainder of the monitoring period (late November). The

water levels increased in early October at the Unnamed Creek piezometers, then had a consistent or

slightly decreasing trend for the rest of October and November.

There appears to be a variable flux between water in Spirit Lake, porewater in sediment, and groundwater

in the Unnamed Creek area. The elevation differences between water levels in piezometers PZ-U-2A, B,

and C varied, indicating a fluctuating vertical hydraulic gradient, and therefore possible reversals in

groundwater/surface water flux directions. The water elevations in the piezometers also fluctuated above

and below the water level of Spirit Lake (Figure 6). The piezometers are installed in sediment adjacent to

an extensive and relatively flat area where minor variability in the Spirit Lake water level can

dramatically alter the shoreline position. The water level changes observed both in the wells and the lake

indicate a hydraulic connection between Spirit Lake and groundwater, and that flow direction may

fluctuate dependent on hydrologic conditions. The flux between Spirit Lake and the underlying sediment

was generally from the lake to the sediment at seepage meters UC-79 and UC-79a, except for three

measurements where flux was from the sediment to the lake. Changes in flux did not necessarily

correspond with water level difference between Spirit Lake and the aquifer(s), with delay times of

approximately one week.

The hydraulic gradient in the Upper Wire Mill area appears to be downward based on the water levels in

piezometers PZ-E-1A, B, and C (Figure 7). The water level ranged from about 2.9 to 4.5 feet and 2 to 3.5

feet above the Spirit Lake water level in piezometers PZ-E-1A and PZ-E-1C, respectively. The water

level in piezometer PZ-E-1B was within 0.25 feet of the level in PZ-E-1A. The water level in all three

piezometers dropped about one foot from November 9 to 13, which appears to coincide with the

formation of ice along the Spirit Lake shoreline. Seepage meters WM-100 and WM-71 appeared to have

delayed responses of about one week to the water level changes in Spirit Lake.




The groundwater levels in the Wire Mill area are spatially variable, with measured elevations in the

PZ-W-1 wells to the north of the Wire Mill pond consistently higher than those of the PZ-W-3 wells

south of the pond (Figure 8). PZ-W-1 wells showed an upward gradient (except that the water level in

piezometer PZ-W-1B decreased about 0.65 feet from November 9 to 13, while the water levels in PZ-W-

1A and PZ-W-1C remained stable), indicating probable local groundwater discharge to the pond. The

water levels in piezometers PZ-W-3A, B, and C decreased about 0.4 feet during that same period, while

indicating an upward vertical gradient between wells PZ-W-3A and B. Similar to the PZ-E-1A, B, and C

piezometers, the decrease in water levels appears to coincide with the formation of ice along the Spirit

Lake shoreline. The usable measurements collected at the Pilot seepage meter showed a net flow of water

from the lake into groundwater (Figure 5). All seepage meter measurements at WM-121 and WM-120

were from Spirit Lake into the sediments, but the shallower WM-121 tended to have higher flux rates.

The measured volumes in the seepage meters were observed to be delayed from significant changes in

water levels in Spirit Lake by about one week.

Response to Comments This section is intended as a response to MPCA comments (MPCA, 2015) regarding potential sources of

error introduced by the use of Tedlar® bags. The MPCA commented on the potential for Tedlar bags to

increase the potential measurement error due to a higher degree of rigidity and an envelope shape which

could cause the bag to expel some water as the bag returns to the original resting condition, causing a

false net downward flux measurement.

Tedlar bags were selected for use in this study because of their wide availability, built-in sample port, and

successful use at the nearby SLRIDT site (Hedblom, et al., 2003). The bags used were constructed of thin

2 mil (0.002 inch) plastic (approximately twice the thickness of human hair, and approximately half the

thickness of a standard piece of paper) and manufactured by SKC, Inc. and were, therefore, quite flexible

and pliant (http://www.skcinc.com/catalog/pdf/instructions/SampleBagBrochure.pdf; Cat.No.232-01).

Although the Tedlar bags used in the study have a flat resting unfilled shape, when filled with air, the

“memory” or elastic effect appears to be relatively slight – i.e., the bag does not quickly return to its

original shape. There is little potential for bag effect errors to influence measurements, especially when

the bags are operated properly – i.e. between 25% and 75% full. Therefore, any error introduced through

use of these very thin Tedlar bags is unlikely to materially alter the overall flux measured.




Anecdotal evidence from field observations support a net downward flux at some locations, primarily in

the Wire Mill area where the water in the bags was mostly clear, indicating that the distilled water was not

significantly mixed with surface water or groundwater, which are typically stained in the St. Louis River.

A review of field notes also indicated three instances (October 26 and 29, 2012, at WM-71, and

November 16, 2012, at WM-121) of notable suction when the bag was detached, indicating a downward

flux.

As noted in the MPCA comments, even if there were measurement errors introduced from the bags and/or

wave action, the measured flux rates were very low, indicating that pore water movement is dominated by

diffusion rather than advection and making it unlikely that impacted pore water will migrate upward into

site caps.

Additional evaluation of flux is on-going in OU-I and OU-M for comparison to these results. Vibrating

wire piezometers, piezometers, and a staff gauge were installed in spring 2015. These additional data will

be used along with existing data to evaluate the flux in areas of potential response actions. The remedial

design will consider all flux evaluations and related data to determine an appropriate isolation zone to

build protective caps.




Additional Observations Regarding Groundwater Discharge This section describes additional observations and measurements to be considered in conjunction with the

seepage meter data to evaluate if there is significant groundwater discharge to Spirit Lake through

sediment that may transport COIs to surface water.

I. Thermal profiling Significant differences between temperatures measured in sediment and overlying surface water may

indicate the presence of upwelling groundwater. Results of sediment-surface water temperature

measurement differences were plotted on a map to guide the future placement of groundwater seepage

meters (Barr 2012 and 2013). Readings revealed differences between surface water and groundwater

temperatures ranging from 0 to 3.1 degrees Celsius. However, when accounting for other factors which

may have influenced temperature readings (i.e. time of day, amount of cloud cover, depth of water,

instrument accuracy) the results were generally inconclusive. No visual evidence of upwelling

groundwater (e.g. roiling water or mud boils) was noted during the profiling.

II. Ice evaluation Ice conditions were observed during the winters of 2011 through 2014 (Barr 2012 and 2014). Open water

at the shore typically persists throughout much of the winter only at the Wire Mill Pond outlet due to

pond discharge at the shore. However, no other areas along the shore of the site were observed that had

open water. This may indicate that there are not major groundwater discharge areas that cause ice to melt

or prevent ice from forming.

III. Seeps/springs

The Wire Mill Pond (Figure 2) appears to be predominantly supplied by groundwater. Several large

seeps are visible at the western edge of the pond, and no major surface water inlets to the pond are visible.

Piezometer PZ-W-2C, at the western edge of the pond, exhibits flowing artesian conditions indicating an

upward gradient. Additionally, water pools are located west of the rail tracks, to the north and south of

the Wire Mill pond. These pools appear also to be fed by groundwater more than precipitation, as they

remain present throughout the year. Groundwater from the hillside near the Wire Mill Pond appears to

discharge west of the rail tracks. East of the railroad tracks, seeps are not observed at the shoreline of

Spirit Lake or through the sediments in the adjacent Wire Mill Delta area.




IV. Prior investigations A conclusion stated by URS (2002) is that horizontal groundwater flow directions at the Former U. S.

Steel Operations Area have typically been toward the St. Louis River. Seasonal fluctuations in

groundwater flow direction were observed near the Unnamed Creek Delta, but not near the Wire Mill

Pond. Horizontal hydraulic gradients near the Unnamed Creek Delta were relatively flat, ranging from

0.0006 – 0.002, with both upward and downward vertical hydraulic gradients. Horizontal hydraulic

gradients near the Wire Mill Pond (west of the railroad tracks) ranged from 0.009 to 0.014, with vertical

hydraulic gradients typically upward.

URS (2002) also concluded that, “While the potential for vertical flow exists, actual vertical flow appears

to be limited by site geology.” Stratigraphy examined during URS’s investigations indicated laterally

extensive (up to 300 feet offshore) clay, silt, and peat deposits that may act as confining units that limit

vertical upward and downward flow of groundwater. These laterally extensive, low permeability units

were confirmed in recent investigations of cores, borings and cone penetrometer tests (CPTs) (Barr,

2013). Discharge of groundwater from the more permeable lower layers of material may be to areas

where the deeper layers are intersected by the deeper river channel on the east and north sides of Spirit

Lake (outside the project Study Area).

V. Porewater dissipation and permeability tests Pore pressure dissipation (PPD) tests taken during CPTs are used to provide an indication of relative

hydraulic conductivity. Excess pore water pressure data indicates the possible presence of low

permeability sediment (ASTM D5778, 2012). PPD tests were performed at select intervals during CPT

testing during the RI (Barr 2012). PPD test data are available from two locations in the Unnamed Creek

CPT-303 (UC-93), CPT-304 (UC-92), and two locations in the Wire Mill area: CPT-314 (WM-101), and

CPT-316 (WM-103) at approximate depths of 4.6, 4.6, 31.8, and 4.8 feet below the riverbed, respectively.

Soil hydraulic conductivity from the PPD tests range from 5x10-8 to 2x10-5 centimeters per second (cm/s).

Permeability tests were performed in the laboratory on three Shelby tube samples collected from UC-96

5-7.5’, WM-100 3-5.5’, and WM-101 27.5-30’. Hydraulic conductivity values from these tests range

from 3.0x10-7 to 2.0x10-6 cm/s.




VI. Porewater sample results Porewater concentrations are most indicative of potential toxicity of sediment to benthic invertebrates that

live in sediment. Porewater samples were collected from locations that covered a range of bulk sediment

PAH, metal, TOC, and black organic carbon sediment concentrations. The porewater results indicated

that PAHs were sorbed more to sediments than would have been predicted by published equilibrium

partitioning coefficients for organic carbon (EA, 2013b). Metals porewater results were only collected

from the Wire Mill delta and the results were inconclusive. Increased sorption of COIs to sediment may

reduce advective flow of COIs from porewater/groundwater to surface water.

Conclusions This section compares the results of this investigation to the objectives of the study.

(1) evaluate whether advective flow has the potential to transport chemicals of interest through

sediment to surface water:

Increases of volume in the seepage meter bags, which indicate that groundwater is welling up through the

sediments, occurred in only four of 53 readings (7.5% of the readings). The majority of measurements

indicate that the predominant flow direction was from Spirit Lake into the aquifer(s) during the study.

The seepage meters were placed at various locations to test differences in a variety of settings, including

differences in topography/bathymetry, surface sediment type, proximity to observed shoreline seep

locations and surface water discharges, and in different sediment/surface water profiling regimes (Barr,

2012). Since 92.5% of the measurements indicate that the net groundwater flux is into the sediments, the

flux measurements do not appear to be significantly sensitive to the variations among the above-listed

factors. Advective flow is unlikely to transport chemicals of interest through the sediment to surface

water, based on the seepage meter study which indicates the predominant flow is downward from Spirit

Lake into the underlying aquifer. Groundwater levels in piezometers appeared to lag changes in lake

levels during the study period, but did not appear to correlate with changes in measured seepage direction

from the lake to the sediment.

The results of this study, in conjunction with ice observations, observations of seeps and springs to the

west of the rail tracks along the shoreline, and results of prior investigations including porewater sampling

conducted in nearby areas, indicate that advective flow of groundwater through sediments into Spirit Lake




is not a pathway of concern for the Conceptual Site Model (CSM). Any measurement errors potentially

introduced by the use of Tedlar® bags is likely small and unlikely to materially change the fluxes

measured or the conclusions of this study. Even if there were small measurement errors introduced from

the bags and/or wave action, the measured flux rates were very low, indicating that pore water movement

is dominated by diffusion rather than advection.

(2) provide information on how groundwater/surface water interaction may affect possible future

sediment management alternatives evaluated for the Feasibility Study:

The information gathered in this Study will be used for the evaluation of sediment management

alternatives.

(3) evaluate whether ebullition is occurring at the Site:

Ebullition was not observed at any of the locations during seepage meter installation, monitoring, or

removal.




References ASTM Standard D5778 – 12, 2012. Standard Test Method for Electronic Friction Cone and Piezocone

Penetration Testing of Soils. ASTM International, West Conshohocken, PA, 2003, DOI:

10.1520/D5778-12, www.astm.org.

Barr Engineering Company (Barr), 2012. Groundwater/Surface Water Flux Meter Sampling and Analysis

Plan: Spirit Lake Sediment Site, Former U. S. Steel Duluth Works, Saint Louis River, Duluth

Minnesota. Prepared August 2012 for U. S. Steel.

Barr, 2013. Sediment Remedial Investigation Report- Great Lakes Legacy Act Project, Spirit Lake

Sediment Site, Former U. S. Steel Duluth Works, Saint Louis River, Duluth, Minnesota. Prepared

March 2013 for U.S. Steel.

Barr, 2014. Ice Evaluation Report - Great Lakes Legacy Act Project, Spirit Lake Sediment Site, Former

U. S. Steel Duluth Works, Saint Louis River, Duluth, Minnesota.

Barr, et al., 2014. Feasibility Study-Former Duluth Works and Spirit Lake Sediment Site. Prepared for

Great Lakes Legacy Act Partnership between United States Steel Corporation, and United States

Environmental Protection Agency, Great Lakes National Program Office,, In Consultation with

Minnesota Pollution Control Agency. Prepared by Barr Engineering Company, EA Engineering,

Science, and Technology, Inc., and URS Corporation, November 2014.

EA Engineering, Science, and Technology, Inc., 2013b. Technical Memorandum for Comparison of

Surficial Porewater and Sediment Concentrations of Polycyclic Aromatic Hydrocarbons and

Metals, Spirit Lake Sediment Site, St. Louis River Area of Concern, Duluth, MN. Prepared

December 2013 for U.S. Environmental Protection Agency.

Hedblom, E., Costello, M., and Huls, H., 2003, Integrated field sampling for design of a remedial

cap: Cincinnati, Ohio, Proceedings of the In-Situ Contaminated Sediment Capping Workshop,

May 12–14, 2003, p. 19.

MPCA, 2013. MPCA email message to John Prusiecki (USS) from Susan Johnson (MPCA)

regarding –acknowledgement of the SAP for porewater sampling.




MPCA, 2015. MPCA Comments for the US Steel Feasibility Study. Electronic mail communication

MPCA, February 9, 2015.

URS Corporation, 2002. Hydrogeologic Investigation of the U. S. Steel Former Duluth Works Site.

Prepared for U. S. Steel Corporation, June 7, 2002.

Attachment A

Figures

ApproximateU. S. Steel

Operations Area

Spirit Lake

Wire Mill Delta

Unnamed Creek Delta

Spirit Island

Unn

amed Creek

Railw

ay

Wire Mill Pond

MorganPark

Gary - New Duluth

St. Louis River

St. Loui

s R

iver

Ch

an

ne

l

MIN

NESO

TA

WIS

CO

NSIN

Figure 1

SITE LOCATION

Spirit Lake Sediment Site - Former U. S. Steel Duluth Works

Saint Louis RiverDuluth, Minnesota

0 2,000 4,000

Feet

1 Inch = 2,000 Feet

!;N

Approximate U. S. SteelOperations Area (URS, 2008)

State Boundary

Barr Footer: ArcGIS 10.0, 2012-08-07 10:41 File: I:\Client\USS_Duluth_Works\Work_Orders\Feasibility_Study_Work_Plan\Maps\Reports\Figure 1 Site Location.mxd User: JLC

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")

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")

"

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"

"

"

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")")

")")

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")")

")")

Approx im ateU . S. Ste e lOpe rationsArea

Unnamed CreekDelta

MorganPark

Railway

Wire MillDelta

Wire Mill Pond

Spirit Lake

St. Louis River Channel

Spirit Island

Unna

me

d Creek

MINNESOTA

WISCONSIN

(Elevation approx. 601.1 ft.)

Proposed UC-79

Proposed WM-71

Proposed WM-10

Proposed WM-14

Proposed WM-100

Proposed UC-79A

WM-120

WM-100

UC-79

WM-71

WM-121

PILOT

UC-79APZ-U -2

PZ-E-1

PZ-W-1

PZ-W-3

") Installe d Groundwate r Flux Me te r Locations

" Propose d Ground wate r Flux Me te r Locations (6)

") Pie zom e te r Ne st Location

Approx im ate Oute r Stud y Area Lim itApprox im ate Location of St. Louis Rive r Ch anne l, Base d on Orth oph oto Inte rpre tationApprox im ate U . S. Ste e l Ope rations Area (U RS, 2008)

State Bound ary

Barr Footer: ArcGIS 10.2.1, 2014-05-08 11:10 File: I:\Client\USS_Duluth_Works\Work_Orders\Feasibility_Study\Maps\Flux_Meter\Figure 1 Proposed and Installed Groundwater Flux Meter Locations.mxd User: sal2

Figure 2PROPOSED AND INSTALLED

GROUNDWATER FLUXMETER LOCATIONS

Spirit Lak e Se d im e nt Site -Form e r U . S. Ste e l Duluth Work s

Saint Louis Rive rDuluth , Minne sota

Orth oph oto: Farm Se rvice Age ncy, 2008.

0 800 1,600Fe e t

!;N

Note : Flux m e te rs WM-10 and WM-14 we re installe d close r to sh ore th an propose d be cause Spirit Lak ewas d e e pe r th an e x pe cte d in th at are a. Th e flux m e te r nam e s we re ch ange d from WM-10 to WM-120and from WM-14 to WM-121 to accurate ly re pre se nt th e actual m onitoring locations.”

Top view Side view

Figure 3. Diagram of seepage meters used at the site.

Drum caps (sealed)

Vinyl tubing inside rubber stopper

~ 22.5 inches

Vinyl tubing

Silicone tubing

Tedlar ® bag

Sediment

Silicone tubing

Tedlar® bag

Rubber stopper

Figure 4. Volume change measurements from all seepage meters.

Figure 5. Data from the Pilot seepage meter and nearest piezometers plotted with precipitation and Spirit Lake elevations.

Figure 6. Data from seepage meters and nearest piezometers in the Unnamed Creek area plotted with precipitation and Spirit Lake elevations.

Figure 7. Data from seepage meters and nearest piezometers in the Upper Wire Mill area plotted with precipitation and Spirit Lake elevations.

Figure 8. Data from seepage meters and nearest piezometers in the Wire Mill Pond area plotted with precipitation and Spirit Lake elevations

Attachment B

Tables

Table 1 2012 Proposed vs. Actual Sample Locations* - Groundwater Seepage Meters

Spirit Lake Sediment Site U. S. Steel Former Duluth Works

Proposed

Location IDX_SP_Feet Y_SP_Feet Actual Location ID X_SP_Feet Y_SP_Feet

Top of Drum Elevation

Sediment Elevation

Delta x Delta y Notes

WM-100 2849780.55 395879.456 WM-100 2849760.22 395870.66 600.31 599.67 20.33 8.79 --WM-141 2851157.16 394262.95 WM-121 2850618.58 394175.78 600.76 600.10 538.58 87.17 --WM-102 2850783.46 394279.3 WM-120 2850679.23 394060.57 600.19 599.65 104.23 218.73 --WM-71 2850555.69 395060.7601 WM-71 2850515.09 395043.09 600.06 599.56 40.60 17.67 --UC-79A 2850961.154 398050.6568 UC-79A 2850953.81 397984.88 600.07 599.25 7.35 65.78 --UC-79 2850764.13 397881.8001 UC-79 2850768.94 397878.20 600.76 600.11 -4.81 3.61 --

-- -- -- PILOT 2850337.49 394332.01 601.11 600.54 -- -- Pilot meter*All coordinates are in NAD 1983 HARN StatePlane Minnesota (feet)1, 2Locations inaccessible by wading, moved to new location.

Table 2 Net Groundwater/Surface Water Flux Measured at Each Seepage Meter


Start Date End Date

Pilot cm3/day

WM‐121cm3/day

WM‐120cm3/day

WM‐71cm3/day

WM‐100 cm3/day

UC‐79 cm3/day

UC‐79Acm3/day

8/29 8/31 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 8/31 9/05 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/05 9/07 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/07 9/10 ‐8.19 ‐ ‐ ‐ ‐ ‐ ‐ 9/10 9/12 ‐143.75 ‐ ‐ ‐ ‐ ‐ ‐ 9/12 9/14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/14 9/18 ‐111.57 ‐ ‐ ‐ ‐ ‐ ‐ 9/18 9/21 ‐172.95 ‐ ‐ ‐ ‐ ‐ ‐ 9/21 9/26 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/26 9/28 ‐134.49 ‐ ‐ ‐ ‐ ‐ ‐ 9/28 10/9 ‐258.92 ‐ ‐ ‐ ‐ ‐ ‐ 10/09 10/12 ‐954.48 ‐ ‐ ‐ ‐ ‐ ‐ 10/12 10/15 ‐971.51 ‐153.66 ‐41.02 ‐166.73 10.22 ‐ 118.42 10/15 10/19 ‐ ‐ ‐101.06 ‐129.16 ‐104.01 ‐ ‐32.23 10/19 10/23 ‐ ‐93.62 ‐ ‐ ‐ 8.83 ‐80.62 10/23 10/26 ‐ ‐ ‐56.06 ‐ ‐112.24 ‐ ‐ 10/26 10/29 ‐ ‐ ‐52.13 ‐19.75 ‐164.54 ‐150.17 ‐128.63 10/29 11/02 ‐ ‐116.33 ‐60.90 ‐113.58 ‐125.41 ‐ ‐72.88 11/02 11/06 ‐114.77 ‐112.55 ‐103.74 ‐110.87 ‐ ‐71.32 ‐108.90 11/06 11/09 ‐ ‐90.95 ‐133.73 ‐46.68 ‐115.4 ‐123.76 ‐154.73 11/09 11/13 ‐ ‐ ‐87.22 ‐96.36 ‐ ‐ 169.68 11/13 11/16 ‐135.21 ‐158.87 ‐110.77 ‐38.88 ‐55.30 ‐ ‐39.00

Average ‐300.58 ‐121.00 ‐82.96 ‐90.25 ‐95.24 ‐84.11 ‐36.54 Note: Negative values indicate that the net direction of flow is from Spirit Lake to groundwater. ‐ Seepage meter not installed ‐ Seepage meter measurement removed from analysis because of known source of error ‐ Seepage meter bag broken ‐ Seepage meter could not be sampled because of high water

Table 3 Net Groundwater/Surface Water Velocity Calculated at Each Seepage Meter


Start Date End Date

Pilot cm/day

WM‐121cm/day

WM‐120cm/day

WM‐71cm/day

WM‐100 cm/day

UC‐79 cm/day

UC‐79Acm/day

8/29 8/31 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 8/31 9/05 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/05 9/07 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/07 9/10 ‐0.003 ‐ ‐ ‐ ‐ ‐ ‐ 9/10 9/12 ‐0.056 ‐ ‐ ‐ ‐ ‐ ‐ 9/12 9/14 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/14 9/18 ‐0.043 ‐ ‐ ‐ ‐ ‐ ‐ 9/18 9/21 ‐0.067 ‐ ‐ ‐ ‐ ‐ ‐ 9/21 9/26 ‐ ‐ ‐ ‐ ‐ ‐ ‐ 9/26 9/28 ‐0.052 ‐ ‐ ‐ ‐ ‐ ‐ 9/28 10/9 ‐0.101 ‐ ‐ ‐ ‐ ‐ ‐ 10/09 10/12 ‐0.371 ‐ ‐ ‐ ‐ ‐ ‐ 10/12 10/15 ‐0.378 ‐0.060 ‐0.016 ‐0.065 0.004 ‐ 0.046 10/15 10/19 ‐ ‐ ‐0.039 ‐0.050 ‐0.040 ‐ ‐0.013 10/19 10/23 ‐ ‐0.036 ‐ ‐ ‐ 0.003 ‐0.031 10/23 10/26 ‐ ‐ ‐0.022 ‐ ‐0.044 ‐ ‐ 10/26 10/29 ‐ ‐ ‐0.020 ‐0.008 ‐0.064 ‐0.058 ‐0.050 10/29 11/02 ‐ ‐0.045 ‐0.024 ‐0.044 ‐0.049 ‐ ‐0.028 11/02 11/06 ‐0.045 ‐0.044 ‐0.040 ‐0.043 ‐ ‐0.028 ‐0.042 11/06 11/09 ‐ ‐0.035 ‐0.052 ‐0.018 ‐0.045 ‐0.048 ‐0.060 11/09 11/13 ‐ ‐ ‐0.034 ‐0.037 ‐ ‐ 0.066 11/13 11/16 ‐0.053 ‐0.062 ‐0.043 ‐0.015 ‐0.022 ‐ ‐0.015

Average ‐0.12 ‐0.05 ‐0.03 ‐0.04 ‐0.04 ‐0.03 ‐0.01 Note: Negative values indicate that the net direction of flow is from Spirit Lake to groundwater. ‐ Seepage meter not installed ‐ Seepage meter measurement removed from analysis because of known source of error ‐ Seepage meter bag broken ‐ Seepage meter could not be sampled because of high water

groundwater/surface water seepage meter sampling and ... · technical memorandum to: revised...

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