North Boeing Field/ 

Georgetown Steam Plant Site 

Remedial Investigation/Feasibility Study 

Expanded Stormwater Sampling 

Interim Data Report 

Prepared for 

Washington State Department of Ecology 

Toxics Cleanup Program 

Northwest Regional Office 

Bellevue, WA 

Prepared by 

Science Applications International Corporation 

18912 North Creek Parkway, Suite 101 

Bothell, WA 98011 

September 2010 
LIMITATIONS 

SAIC’s investigation was restricted to collection and analysis of a limited number of 

environmental samples, visual observations, and field data, in addition to summarizing available 

information from previous site documents. Because the current investigation consisted of 

evaluating a limited supply of information, SAIC may not have identified all potential items of 

concern. This report is intended to be used in its entirety; taking or using excerpts from this 

report is discouraged. 
Expanded Stormwater Sampling Interim Data Report 

 

Table of Contents 

Page

1.0 Introduction ........................................................................................................................1

1.1 Site Description ................................................................................................................2

1.2 Project Scope and Study Objectives ................................................................................2

1.3 Document Organization ...................................................................................................3

2.0 Data Collection and Analytical Methods .........................................................................4

2.1 Flow Measurements .........................................................................................................5

2.2 Sample Collection ............................................................................................................5

2.2.1 Filtered Suspended Solids Samples .........................................................................6

2.2.2 Whole Water Samples ..............................................................................................7

2.2.3 Base Flow Samples ..................................................................................................8

2.2.4 Particle Size Fractionation Samples .........................................................................8

2.2.5 Parking Lot Surface Solids Samples ........................................................................8

2.3 Chemical Analysis ...........................................................................................................9

2.3.1 Filtered Suspended Solids Samples .........................................................................9

2.3.2 Whole Water Samples ..............................................................................................9

2.3.3 Particle Size Fractionation Samples .........................................................................9

2.3.4 Surface Solids Samples ..........................................................................................10

3.0 Flow Measurement Results .............................................................................................11

3.1 Flow Measurements and Precipitation ...........................................................................11

3.1.1 Precipitation ...........................................................................................................11

3.1.2 Tide ........................................................................................................................11

3.1.3 Stormwater Flow Records......................................................................................11

3.1.4 Event Summaries ...................................................................................................14

4.0 Chemistry Results ............................................................................................................15

4.1 Filtered Suspended Solids Sampling .............................................................................15

4.1.1 Physical Parameters ...............................................................................................15

4.1.2 Chemical Analysis .................................................................................................16

4.2 Whole Water Sampling ..................................................................................................19

4.2.1 Physical Parameters ...............................................................................................19

4.2.2 Chemical Analysis .................................................................................................20

4.3 Particle Size Fractionation .............................................................................................21

4.4 Surface Solids Samples ..................................................................................................21

5.0 Quality Assurance/Quality Control................................................................................23

6.0 Summary ...........................................................................................................................24

7.0 References .........................................................................................................................25

Appendix A Totalizer Logs 

Appendix B Monthly Precipitation Summaries 

Appendix C Laboratory Data Reports 

Appendix D Data Validation Report 

September 2010 Page i 
Interim Data Report Expanded Stormwater Sampling 

Figures 

Figure 1. Overview of NBF-GTSP Location 

Figure 2. NBF Storm Drain Lines 

Figure 3. Expanded Stormwater Sampling Locations 

Figure 4. Parking Lot Surface Solids Sampling Locations 

Figure 5. Runoff Volume Versus Precipitation 

Figure 6. Mercury Concentrations in Filtered Suspended Solids 

Figure 7. Total PCB Concentrations in Filtered Suspended Solids 

Figure 8. HPAH Concentrations in Filtered Suspended Solids 

Figure 9. TSS Concentrations in Whole Water and Filtered Suspended Solids 

Figure 10. Total PCB Concentrations in Whole Water and Filtered Suspended Solids 

Tables 

Table 1. Samples Collected and Issues Encountered During Stormwater Sampling Events 

Table 2. Samples Collected and Issues Encountered During Base Flow Sampling Events 

Table 3. Chemical and Physical Analysis of Filtered Solids Samples 

Table 4. Summary of Results for Filtered Suspended Solids Samples at MH108 

Table 5. Summary of Results for Filtered Suspended Solids Samples at LS431 

Table 6. Summary of Results for Filtered Suspended Solids Samples for Other SD Lines 

Table 7. Summary of Results for Filtered Suspended Solids Samples in the North Lateral SD 

Line 

Table 8. Summary of Results for Whole Water Samples at MH108 

Table 9. Summary of Results for Whole Water Samples at LS431 

Table 10. Summary of Results for Analysis by Grain Size Fractionation 

Table 11. Summary of Results for Parking Lot Surface Solids Samples 

Page ii September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

List of Acronyms 

μg microgram 

μm micron 

2LAET second lowest apparent effects threshold 

ARI Analytical Resources, Inc. 

CSL Cleanup Screening Levels 

DOC dissolved organic carbon 

EAP Environmental Assessment Program 

Ecology Washington State Department of Ecology 

EOF emergency overflow 

EPA U.S. Environmental Protection Agency 

FC freshwater criteria 

ft/s feet per second 

g gram 

gpm gallons per minute 

GTSP Georgetown Steam Plant 

HHO human health for consumption of organisms 

HPAH high molecular weight polycyclic aromatic hydrocarbon 

KBFI Seattle Boeing Field-King County International Airport rain gauge 

KC King County 

KCIA King County International Airport 

kg kilogram 

L liter 

LAET lowest apparent effects threshold 

LDW Lower Duwamish Waterway 

LPAH low molecular weight polycyclic aromatic hydrocarbon 

LS lift station 

m/s meters per second 

mg milligram 

MH manhole 

mL milliliter 

MLLW mean lower low water 

mm millimeter 

MWC marine water criteria 

NBF North Boeing Field 

NOAA National Oceanic and Atmospheric Administration 

PAH polycyclic aromatic hydrocarbon 

PCB polychlorinated biphenyl 

pg picogram 

QAPP Quality Assurance Project Plan 

RI/FS Remedial Investigation/Feasibility Study 

SAIC Science Applications International Corporation 

September 2010 Page iii 
Interim Data Report Expanded Stormwater Sampling 

Page iv September 2010 

List of Acronyms (continued) 

SAP sampling and analysis plan 

SD storm drain 

SIM Selective Ion Monitoring 

SMS Sediment Management Standards 

SOP standard operating procedure 

SQS Sediment Quality Standard 

SVOC semi-volatile organic compound 

TEF toxic equivalency factor 

TEQ toxic equivalent quotient

TOC total organic carbon 

TSS total suspended solids 

USEPA U.S. Environmental Protection Agency 

VOC volatile organic compound 

WAC Washington Administrative Code 

WHO World Health Organization 
Expanded Stormwater Sampling Interim Data Report 

 

1.0 Introduction 

Stormwater discharge from the North Boeing Field-Georgetown Steam Plant (NBF-GTSP) Site 

is a potential source of contaminants to Slip 4 on the Lower Duwamish Waterway (LDW). The 

Washington State Department of Ecology (Ecology) and the U.S. Environmental Protection 

Agency (USEPA) identified cleanup of contaminated sediment in Slip 4 as a high priority for the 

LDW Superfund Site. Cleanup of Slip 4 has been delayed because of concerns about the 

potential recontamination of sediments in Slip 4 from releases of contaminants from this site. A 

Remedial Investigation/Feasibility Study (RI/FS) and cleanup of this site is necessary to allow 

sediment cleanup in Slip 4 to proceed. Because of the long time frame associated with 

completing the RI/FS, USEPA asked Ecology to investigate options that might allow the cleanup 

of Slip 4 to proceed. 

To facilitate this process, Ecology tasked Science Applications International Corporation (SAIC) 

with the collection of stormwater and continuous flow measurements from the storm drain (SD) 

line upstream of the King County International Airport (KCIA) SD#3/PS44 emergency overflow 

(EOF) outfall to Slip 4. In September 2009, stormwater sampling systems were installed at two 

locations on the NBF-GTSP site: a manhole on the downstream side of the King County lift station 

(LS431), and manhole MH108 on the north lateral SD line. Whole water and filtered suspended 

solids samples were collected at both locations during five storm events as part of the 

preliminary stormwater sampling task. Sampling results were documented in a Preliminary 

Stormwater Sampling Interim Data Report (SAIC 2010a). 

Based on a preliminary conceptual site model (SAIC 2010b) and input from Ecology, USEPA, 

Boeing, the City of Seattle, and King County, additional sampling needs were identified. The 

original stormwater sampling task was expanded to include an additional five storm events at 

these two locations, plus sampling at new locations in the north lateral SD line and in each of the 

other lateral SD lines at NBF. Base flow sampling was also included to assess the contribution of 

contaminants in base flow to discharges from the KCIA SD#3/PS44 EOF outfall. Additional 

samples were collected to determine the concentrations of various chemicals of concern in 

different particle size fractions, in support of Slip 4 sediment recontamination modeling. 

This report includes the chemical analysis results for filtered suspended solids and whole water 

samples collected at 13 locations during the course of the expanded stormwater sampling phase 

(February through July 2010). Results from the Preliminary Stormwater Sampling Interim Data 

Report (SAIC 2010a) are included to present a comprehensive account of stormwater data 

collected at NBF-GTSP. 

In addition, continuous flow measurements collected over the duration of sampling are reported. 

These measurements will be used in conjunction with the chemistry data to calculate 

contaminant loadings to Slip 4. These loadings will be reported in a separate technical 

memorandum. Sampling was conducted following the study design and methods described in the 

August 2009 Sampling and Analysis Plan and Quality Assurance Project Plan for Preliminary 

Stormwater and Filtered Suspended Solids Sampling (SAIC 2009a) and the April 2010 Work 

Plan and SAP/QAPP Addendum Expanded Stormwater Monitoring (SAIC 2010b). 

September 2010 Page 1 
Interim Data Report Expanded Stormwater Sampling 

1.1 Site Description 

The NBF-GTSP Site is located east of Slip 4 and approximately 4 miles south of downtown 

Seattle. NBF is located at 7500 East Marginal Way S and occupies approximately 130 acres 

primarily within the Seattle and Tukwila city limits (Figure 1). The site is leased by Boeing from 

King County, with the exception of a few acres on either side of the former GTSP flume, which 

is leased from the City of Seattle, and Building 3-390 and an adjacent parcel used for parking, 

which are owned by Boeing. The head of Slip 4 is approximately 150 feet from the northwestern 

boundary of NBF. 

The NBF SD system drains a total area of approximately 328 acres; this includes stormwater 

flow from 171 acres of KCIA, which enters the site from the north and east at four locations 

(SAIC 2009b). Most areas of NBF drain to one of four lateral SD lines (the north, north-central, 

south-central, and south lateral SD lines), which are directed to a trunk line that passes through a 

King County (KC) lift station, under East Marginal Way S, and to the 60-inch KCIA SD#3/PS44 

EOF outfall at Slip 4 (Figure 2). Stormwater from a smaller area near Building 3-380 (which 

previously discharged to Slip 4 via a separate SD line) and a parking area downstream of the lift 

station also drain to Slip 4. 

1.2 Project Scope and Study Objectives 

The purpose of the expanded stormwater sampling effort was to collect samples of whole water 

and filtered suspended solids during five storm events at LS431 and MH108. During three of 

these events, filtered solids were collected near the downstream end of each lateral SD line and 

from up to six locations in the north lateral SD line. Filtered solids and whole water were 

collected from base flow during two time periods near the beginning and end of the expanded 

sampling task. Specific objectives for sampling are as follows: 

• Obtain a larger data set for whole water and filtered solids at LS431 and MH108 to allow 

for a better determination of the relationship between these two sample types. Continued 

sample collection at these two locations will allow for a more accurate calculation of 

contaminant loadings from the north lateral SD line relative to the entire site. 

• Conduct base flow sampling at LS431 and MH108 to assess contaminant loadings due to 

infiltration of groundwater to the SD system. 

• Collect filtered solids samples from the north-central SD line, south-central SD line, 

south SD line, Building 3-380 drainage, and parking lot area to assess contaminant 

contribution (polycyclic aromatic hydrocarbons [PAHs], metals, polychlorinated 

biphenyl [PCBs], dioxins/furans) from areas outside the north lateral SD area, to assess 

whether PCB source control actions taken in the north lateral SD line are sufficient to 

reduce the potential for Slip 4 sediment recontamination. 

• Collect filtered solids at six locations upgradient of MH108 in the north lateral SD line to 

identify and trace sources of PCBs in the north lateral SD line and allow any needed 

interim actions to focus on specific sub-drainages of concern. 

• Determine concentrations of PCB Aroclors, metals, and PAHs in four different particle 

size fractions. 

Page 2 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

• Compare chemistry results from all SD lines to relevant surface water or sediment 

criteria. 

1.3 Document Organization 

The primary purpose of this report is to summarize and evaluate the results of the expanded 

phase of the NBF-GTSP stormwater investigation. Results from the preliminary stormwater 

investigation have been incorporated into this document for overall comparisons of results. 

Section 1.0 describes the NBF-GTSP site and document organization. Section 2.0 describes 

sampling methods that differed from the preliminary stormwater investigation or the SAP/QAPP 

Addendum (SAIC 2010b). Flow measurement data are summarized in Section 3.0. Analytical 

results for filtered suspended solids and whole water are presented in Section 4.0. Section 5.0 

summarizes the data validation reports. A summary of findings is presented in Section 6.0. 

References are listed in Section 7.0. The appendices include totalizer logs, event flow and 

precipitation summaries, laboratory results, and data validation reports. 

September 2010 Page 3 
Interim Data Report Expanded Stormwater Sampling 

2.0 Data Collection and Analytical Methods 

This section describes the collection of flow measurement data and the sampling and analytical 

methods associated with filtered suspended solids, whole water, and base flow samples. 

Samples were collected at 13 locations described below (Figure 3): 

• LS431, located on the discharge (southwest) side of the KC lift station. All four major SD 

lines plus the Building 3-380 line drain to the lift station prior to entering Slip 4. 

• MH356, located on the southwestern corner of Building 3-369, approximately 45 meters (150 

feet) upgradient of the lift station. This location is near the downstream end of the south lateral 

SD line. 

• MH369, located at the north end of the small parking lot on the northwest side of Building 3-

390. This location is 210 meters (700 feet) upgradient of the lift station on the south central 

lateral SD line. 

• MH226, located in a flight apron 58 meters (190 feet) north of MH369. MH226 is on the north 

central lateral SD line, 107 meters (350 feet) upgradient of the junction with the north lateral 

SD line. 

• MH108, located along the north lateral SD line, north of Building 3-380 and near the corner 

of Building 3-350. MH108 was selected to represent stormwater drainage from the north 

lateral SD line. MH108 is located 85 meters (275 feet) upstream of the connection between 

the north and north-central SD lines. 

• CB423, located between Building 3-380 and the lift station. Flow through CB423 is 

representative of the Building 3-380 drainage. 

• MH434, located 23 meters (75 feet) downstream of the lift station. MH434 is representative 

of flow from a section of parking lot bordering East Marginal Way S and additional parking 

spaces within NBF. MH434 was the only drainage area sampled that does not drain to the lift 

station. 

• MH133D, on an extension of the north lateral SD line southwest of Building 3-315. 

• MH178 and CB173, in the parking lot west of Building 3-323 and about 23 meters (75 feet) 

southwest of the GTSP boundary. These locations are the farthest upgradient structures 

sampled as part of the expanded stormwater sampling program. CB173 drains NBF property. 

Flow at MH178 enters from off site. 

• CB165 is northwest of Building 3-322. This location was adjacent to the March 2010 soil 

excavation area near Buildings 3-322 and 3-302. 

• MH152 and MH138 are southwest of Building 3-626. 

Two locations proposed in the SAP/QAPP Addendum (SAIC 2010b) could not be sampled. 

Proposed sampling at MH160 was not possible due to insufficient stormwater flow. MH169 is 

within the fuel test area. Sampling at this location would have required explosion proof sampling 

equipment. Designing and implementing this equipment was cost prohibitive. 

Page 4 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

There were two other substantial deviations from the SAP/QAPP Addendum. Up to 20 grab 

samples were to have been collected at various locations. Between March and May 2010, Landau 

collected grab samples at all NBF SD structures, which contained sufficient material to sample 

(Landau 2010). Boeing subsequently cleaned out all catch basins in the north lateral SD line. 

Additional grab sampling locations were not identified. In place of the grab samples, six parking 

lot surface solids samples were collected to address potential data gaps associated with filtered 

solids collection at MH434. 

Tidal inflow was a frequent problem at MH434. All samples collected at MH434 consisted of 

tidal water co-mingled with stormwater. Filtered solids results may not be representative of the 

sampled event. Surface solids samples were collected near Drain 283A and Drain 436A, two 

samples were collected from an area south of Drain 435B, and two samples were collected from 

an area south of Drain 434A (Figure 4). The surface solids samples represent material in the 

parking lot that is adjacent to the SD trench drains and could therefore enter the SD system and 

be transported to Slip 4. 

2.1 Flow Measurements 

All stormwater flow measurements were collected using Teledyne Isco (Isco; Lincoln, NE) 

equipment leased from Whitney Equipment, Bothell, WA. Clearcreek Contractors performed all 

confined space entry necessary for the Isco installation at each of these locations. 

Sampling equipment at MH108 and LS431 was installed as part of the preliminary stormwater 

sampling (SAIC 2010a). Continuous flow measurements at LS431 were collected using an Isco 

6712 stormwater sampler equipped with a Model 750 area velocity flow module. AC power from 

the east side of the lift station was available to power the Isco unit. Due to the short cycling time 

of the lift station pumps, the flow sampler was programmed to collect data every 1 minute. 

Continuous flow measurements at MH108 were collected using an Isco Model 4250 flow meter 

run off a 12-volt marine battery. The battery was replaced on a biweekly basis for the duration of 

the sampling period. The flow meter was programmed to collect data every 15 minutes. 

Continuous flow measurements at MH226, MH356, MH369, MH423, and MH434 were 

collected using Isco Model 2150 flow meters. Each unit was powered by two internal 6-volt 

lantern batteries. MH356 and MH434 were set to collect data at 1-minute intervals. The unit at 

MH369 was briefly set to 1-minute intervals, but was switched to 15-minute intervals when the 

sensor was moved (Section 3.1.3). MH226 and MH423 were set to collect data at 15-minute 

intervals. 

2.2 Sample Collection 

Expanded stormwater sample collection efforts began in February and ended in July 2010. Storm 

event-based whole water and filtered suspended solids were collected at up to 13 sample 

locations during a given storm event (Table 1). Base flow samples were collected at LS431 and 

MH108 (whole water and filtered suspended solids) and at CB173 (filtered suspended solids) 

(Table 2). 

September 2010 Page 5 
Interim Data Report Expanded Stormwater Sampling 

A total of six storm events were sampled. Whole water and filtered solids were collected during 

Events 6 through 10. Event 9b involved filtered suspended solids sampling at MH434 and 

CB423 due to previous sampling difficulties at these locations. LS431 was also sampled during 

Event 9b to provide a constant location between events. Base flow samples were collected during 

three time periods. During the first base flow event, whole water was collected at LS431 and 

whole water and filtered solids were collected at MH108. Filtered solids were missed at LS431 

due to sampling error. Filtered solids were collected at LS431 during a second base flow event, 

(Base Flow Event 1b in Table 2). A third base flow event was sampled at the completion of 

expanded stormwater sampling to obtain a whole water and filtered solids sample at both 

locations during the same time frame. 

Sample equipment for each location was stored in a polypropylene garden shed for protection. 

When not in operation, the sheds were moved to a nearby storage location to prevent interference 

with Boeing operations. During sampling, vehicles were parked in front of the flight line sample 

units to provide a buffer in the event of jet blasts. 

The start and end time for each sampling event are based on the times listed on the totalizer log 

sheets (Appendix A). These times are listed separately for each location, and may vary slightly 

between locations depending on when each sample unit was activated. 

2.2.1 Filtered Suspended Solids Samples 

The collection of filtered suspended solids at the expanded stormwater sampling locations was 

performed in a manner consistent with preliminary filtered suspended solids sample collection 

methods, as outlined in the preliminary stormwater sampling SAP/QAPP (SAIC 2009a). Events 

and locations where filtered suspended solids were collected are listed in Table 1. 

Prior to each sampling event, clean, pre-weighed filters were installed in each filter housing and 

the beginning totalizer reading was recorded on the totalizer field form (Appendix A). A 50-

gallon per minute (gpm) pump was positioned in the SD beneath the manhole cover. A float 

switch on the pump was set to trigger sampling when SD water depth exceeded a pre-determined 

depth. Once triggered, water was pumped up through the intake line and split into parallel filter 

housings. Each filter housing contained a 20-inch long, 4-inch diameter filter bag. All filter bags 

were constructed of 5 micron (μm) polypropylene felt. The outflow from each filter housing was 

piped into a totalizer to measure flow. Outflow from both totalizers was combined and piped 

back into the SD. When possible, discharge pipes were installed downstream of the effluent 

pump, avoiding the potential for re-circulating water. After sampling, the final totalizer readings 

were recorded, filter housings were drained, and filters were removed. Residual water was gently 

squeezed from the filter bags. Filter samples were placed in clean, labeled, Ziploc bags and 

stored on ice for delivery to the analytical laboratory. 

Exceptions to this method are described below: 

MH133D, MH138, MH178, and MH423. Field observations made during Event 8 indicated 

that stormwater was not deep enough to trigger continual float switch activation at these 

locations. The periodic activation of the float switch and pump allowed for excess air to enter the 

system, causing air lock and preventing further sampling. 

Page 6 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

Prior to Event 9, pre-washed silica sand was triple bagged inside polypropylene sand bags and 

placed slightly downstream of the effluent pump to increase the water depth. All sand bags were 

tightly secured. During subsequent events, stormwater flows successfully triggered the float 

switches and activated sample equipment at all locations except MH178, which required the 

installation of a second sandbag after Event 9. 

CB165. The float switch was inconsistently activated during Event 8 due to the small vault 

volume and low flow of stormwater. The pump was plugged into an automated timer and set to 

15-minute intervals to prevent the pump from overheating. Prior to Event 9, the discharge pipe 

was removed from the system and stormwater was allowed to continuously re-circulate during 

sampling. 

CB173. No additional modifications were made to this location. It is important to note that the 

SD leaving this structure was engineered to be inverted. During a storm, discharge water from 

the filtration system would flow backwards into the CB173 vault. An unknown quantity of 

stormwater was likely re-circulated though the sample unit during sampling. 

MH434. Stormwater flow during Event 8 inconsistently activated the float switch due to low 

flows. During Event 9, a high tide obscured the stormwater flow. Prior to Event 9b, a weir was 

constructed to allow the stormwater to accumulate to a depth that could be sampled. The weir 

consisted of a 0.15-meter (6-inch) tall piece of wood cut to fit the width of the drain. Ten 

sandbags were secured and positioned to hold the weir in place. 

Several days after Event 9b, field personal noticed the weir had been dislodged and several 

sandbags had moved. It is believed a combination of high velocity flow from the lift station and a 

high tide blocking the flow to Slip 4 resulted in water being diverted toward MH434. Sample 

results collected at this location may not be representative of actual stormwater runoff from the 

parking lot. They are likely a mix of parking lot runoff, tidal water from Slip 4, and stormwater 

discharged from the lift station. 

2.2.2 Whole Water Samples 

Whole water samples were collected using Isco 6712 stormwater sampling units at MH108 and 

LS431. The inlet for the Isco samplers and the flow sensors were mounted adjacent to each other 

on stainless steel scissors brackets. As outlined in the preliminary stormwater sampling SAP 

(SAIC 2009a), the flow sensor and Isco inlet were installed upstream of the filtered solids 

effluent pump at MH108. However, the large vault-like drain configuration at the lift station 

prevented upstream installation of the bracket at LS431. Instead, the flow sensor and inlet were 

installed about 1.5 meters (5 feet) downstream of the effluent pump. The output from the filtered 

solids sampler was designed to discharge an additional 0.6 meter (2 feet) farther downstream. 

Flow weighted sampling programs were selected for each Isco unit prior to a sampling event. 

Flow weighting consists of collecting equal volume aliquots at predetermined volume intervals. 

The aliquot volume was constant at 500 milliliters (mL) for all sampled events. The volume 

interval was calculated using forecasted rainfall totals and the relationship between rainfall and 

stormwater flow established from previous rain events. 

All samples were collected in 5-gallon glass carboys. During sampling, the carboy and collected 

water were stored on ice in the base of the Isco unit. After sampling, the carboy was delivered to 

September 2010 Page 7 
Interim Data Report Expanded Stormwater Sampling 

the analytical laboratory, where the sample was split for analysis. The laboratory was responsible 

for decontamination of the carboy as specified in the SAP/QAPP Addendum (SAIC 2010b). 

Additional information regarding whole water sample events is listed in Table 1. 

2.2.3 Base Flow Samples 

The methods described above for filtered suspended solids and whole water sampling were also 

used to collect base flow samples from MH108 and LS431. During dry periods, the lift station 

pumps are active for less than an hour per day. Base flow sampling spanned a multiple day dry 

period to in order to collect enough solids at the lift station. At the lift station, the Isco sampler 

was set to collect an aliquot every lift station pump cycle. At MH108, the Isco was set to collect 

an aliquot every 4 hours. The filtered solids pump at MH108 was set on a timer at a rate of onehalf hour on, one-half hour off to avoid damage to the pump. A base flow sample was collected 

at CB173 during the second base flow event. The pump ran for one day without a timer. A timer 

was installed on the second day for the remainder of sampling. Table 2 lists the dates of the base 

flow samples. 

2.2.4 Particle Size Fractionation Samples 

Three composite samples were collected for analysis of PCBs, metals, and PAHs by grain size 

fraction. Each sample was split into four size categories: <63 μm, 63 to 250 μm, 250 to 500 μm, 

and >500 μm. A large filtration system consisting of four parallel filter bags was constructed in 

order to obtain enough material for analysis. The system was installed in the lift station vault to 

avoid the intermittent flow at the downstream side of the lift station. 

The sampler was only activated during periods of continuous precipitation in an effort to collect 

solids from stormwater rather than base flow. Precipitation events for these samples did not 

follow the event-based criteria of the regular storm events (Section 3.1.4). Each sample consisted 

of four filters from three events. 

Filters for the first sample were collected between March 26 and March 30, 2010. The second 

sample was collected between April 27 and May 5. The third sample was a composite of two 

different time periods. The first set of filters was collected April 3, the second on April 9, and the 

third on May 20. 

2.2.5 Parking Lot Surface Solids Samples 

Filtered solids collected from the MH434 SD are not representative of stormwater runoff. To 

better evaluate the parking lot as a potential source of contaminated sediment to Slip 4, six 

surface solids samples were collected on July 13, 2010 (Figure 4). 

The channel drains in the parking lot were sampled for surface material. Because drains D434A 

and D435B are long, samples were collected from the north and south ends of both of these 

structures. Additional samples were collected from channel drains D283A and D436A located 

southeast of Building 3-370. Composite samples were obtained from each of these areas to create 

a representative sample of sufficient size for analysis. These composite samples were collected 

from empty parking spaces within several lateral feet of each structure. A separate push broom 

was used at each location. Surface sweepings included surface material such as fragments of 

pavement, vehicle debris, soil, gravel, other fine particulate debris, and organic matter from each 

Page 8 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

area. Cigarette butts were removed from the sample. Areas of liquid oily material or sheen were 

avoided when collecting surface solids. 

Material collected for each sample was combined and homogenized in a clean stainless-steel 

bowl using a clean stainless-steel spoon. The material was placed into appropriately sized sample 

jars, labeled, and stored on ice. Material greater than 6 millimeters (1/4 inch) was removed by 

the sampler prior to filling the sample jars. 

2.3 Chemical Analysis 

All chemical and physical analytical procedures were performed by subcontracted laboratories in 

accordance with Ecology guidelines as outlined in the SAP/QAPP Addendum (SAIC 2010b). 

2.3.1 Filtered Suspended Solids Samples 

After collection, all filters were delivered to Analytical Resources, Inc. (ARI), of Tukwila, WA, 

for processing and analysis. Table 3 lists the filtered suspended solids samples selected for 

analysis. Filtered solids from the “A” filter of the parallel filter setup were first scraped to obtain 

material for analysis of metals and grain size. Approximately 10 grams of material were needed 

for metals analysis, and approximately 20 grams for grain size. If insufficient sample material 

was obtained, mercury was analyzed first, followed by other metals, then grain size. The 

remainder of the filter bag was dried to determine the dry weight of material captured during 

filtration. The dry filter bag was extracted and analyzed for PCB Aroclors. 

The “B” filters from Events 6, 7, 8, and 10 were analyzed for PAHs. Due to the volatility of 

PAHs, the filter was not dried prior to extraction. The “B” filters from Events 9, 9b, Base Flow 

Event 1, and Base Flow Event 2 (pending) were dried and weighed by ARI and sent to Axys 

Analytical Services, Ltd (Axys) of Sidney, BC, for analysis of dioxin/furan congeners by Method 

E1613. Dioxin/furan extracts from Event 9 and 9b were combined for CB423 to ensure enough 

material for analysis. 

Analytical methods are listed in the chemistry summary (Tables 4 through 7). 

2.3.2 Whole Water Samples 

The carboys containing whole water samples were delivered to ARI for splitting and analysis. 

Samples from LS431 and MH108 were analyzed from Storm Events 6, 7, 8, 9, and 10 and Base 

Flow Events 1 and 2 for conventional parameters (hardness, pH, alkalinity, anions, total organic 

carbon [TOC], dissolved organic carbon [DOC], total suspended solids [TSS]), volatile organic 

compounds (VOC), semi-volatile organic carbon (SVOC), SVOC by Selective Ion Monitoring 

(SIM), low level PCBs, and total and dissolved metals. 

Due to instrument problems at ARI, analysis of metals for Event 6 and Base Flow Event 1 were 

sub-contracted to Fremont Analytical, Seattle, WA. All analytical methods are listed in the 

chemistry summary Tables 8 and 9. 

2.3.3 Particle Size Fractionation Samples 

After sampling a precipitation event, filters were delivered to ARI. ARI scraped and composited 

solids from each filter. Solids were archived until a sufficient volume was collected. Total mass 

September 2010 Page 9 
Interim Data Report Expanded Stormwater Sampling 

for each sample ranged from 2,500 to 4,300 grams. ARI passed the composited sample through 

appropriately sized sieves for separation into particle size fractions. During processing, filters 

and other equipment were rinsed with stormwater collected from the filter housings at the lift 

station vault. 

Samples were alternatively analyzed for PCBs, metals, and PAHs. Analytical methods are listed 

in Table 10. 

2.3.4 Surface Solids Samples 

Six surface solids samples were delivered to ARI for analysis. All samples were analyzed for TOC, 

grain size, SIM SVOC, PCB Aroclors, and metals. Analytical methods are listed in Table 11. 

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3.0 Flow Measurement Results 

This section presents a summary of flow measurements collected from the NBF lateral SD lines. 

Measured values for flow are compared to the total area in each of the lateral line drainage areas. 

3.1 Flow Measurements and Precipitation 

Flow data logged by the Isco equipment was managed using the Isco program Flowlink (Version 

5.10.206). All data incorporated into Flowlink are stored in a Microsoft Access database. Local 

precipitation and tide height data were added to the Access database to aid interpretation of the 

storm hydrographs. 

3.1.1 Precipitation 

Precipitation data from the Seattle Boeing Field-King County International Airport rain gauge 

(identified as “KBFI”) was used to represent rainfall at NBF-GTSP (Figure 1). Trace amounts of 

precipitation are reported as “T”, and were replaced with 0.0254 millimeter (mm) (0.001 inch) 

when added to the Access database. Precipitation data from March through July 2010 were 

added to the database. There were no gaps or other obvious recording issues during this time 

period. 

3.1.2 Tide 

Validated tidal data from the Seattle tide station (Station ID 9447130) were used to determine 

tidal inflow at MH434 and LS431. Tide data between October 1, 2009, and June 30, 2010, were 

downloaded from the National Oceanic and Atmospheric Administration (NOAA) website 

(http://coops.nos.noaa.gov/data_menu.shtml?stn=9447130%20Seattle,%20Puget%20Sound,%20

WA,%20WA&type=Tide%20Data). All data were added to the Access database in units of 

meters above mean lower low water (MLLW). 

The heights of the sensors at MH434 and LS431 were determined by comparing the level 

measurements made by the Isco flow sensors with the NOAA tide height. The sensor at MH434 

sits at 3.32 meters MLLW (10.9 feet). The sensor at LS431 sits at 3.84 meters MLLW (12.6 

feet). Figures showing total flow, tidal height, and rainfall for each event at LS431 and MH434 

are presented in Appendix B. The tide was above the level of the sensor at LS431 during Events 

5, 7, and 8. The tide was above the level of the sensor at MH434 during Events 8, 9, 9B, and 10. 

3.1.3 Stormwater Flow Records 

This section summarizes the flow measurements collected from mid-February through early July, 

2010. A regression between volume of stormwater (liters) and precipitation amount (mm) for all 

recorded rain events was created for each location. The intercept of each regression was set to 

zero to prevent negative flow volumes at low precipitation amounts. The slope of each regression 

is a constant representing runoff from each of the lateral line drainages. 

LS431. Flow through the lift station is described in the preliminary stormwater sampling data 

report (SAIC 2010a). Briefly, stormwater runoff from NBF drains to the lift station where it 

collects in an underground storage vault. Up to four pumps are activated to lift the water above 

sea level for discharge to Slip 4. Errors with the flow sensor’s level measurements resulted in 

September 2010 Page 11 
Interim Data Report Expanded Stormwater Sampling 

flows from the lift station being underreported. The original flow was modified by adding a 0.2-

meter (8-inch) correction factor to the level data. Volume versus precipitation regressions for 

both the original (Figure 5a) and modified flow (Figure 5b) were calculated to show the range of 

possible values. As in the preliminary data report, the modified flows are used in the report text 

and figures to describe conditions at the lift station. 

Lift station flow remained between 0.8 and 0.95 m3/s (12,700 to 15,000 gpm) through March. 

Beginning in early April, flows became more variable between pump cycles. Discussions with 

the county revealed that the individual pumps rotate activation. The variable flow is either due to 

calibration issues with the flow sensor or the fact that the lift station pumps need servicing. 

Base flow through LS431 decreased over the duration of expanded stormwater sampling. In midFebruary, base flow was approximately 2,300,000 liters (590,000 gal) per day, equating to an 

average of five pump cycles. Base flow had decreased to just over four pump cycles per day in 

early March. By late June, the pumps were only activated three times per day. 

Figures 5a and 5b show the volume versus precipitation relationships between the original and 

modified flows at LS431. The slope of the original regression is 213,880 liters of stormwater per 

millimeter of precipitation. The slope of the modified relationship is over three times higher at 

722,689 L/mm rain (r2

 = 0.923). 

There were three periods where measurements at the lift station were not recorded. The first 

spanned February 5 through February 19. The second spanned March 12 through March 17. The 

third spanned May 20 through June 1. 

MH356. The portion of the south lateral SD line between the lift station and MH353 is part of 

the storage capacity of the lift station. The water level in this area is dictated by the cycling of the 

lift station. As a result, the flow profile at MH356 is similar to that of LS431 (see Appendix B). 

During base flow conditions, one lift station pump is activated when the water level at MH356 

reaches 0.9 meter (3 feet). Over the course of the 8–10-minute pump cycle, the water level drops 

to 0.35 meter (1.1 feet). After the lift station pump shuts off, the water level rapidly increases to 

about 0.6 meter (2 feet). The velocity and flow are negative during this period of rapid level rise. 

This implies that water is flowing backward over the sensor from elsewhere in the water storage 

area behind the lift station. The water level continues to rise to 0.9 meter. Velocity is too slow to 

measure during this period of slow level rise. 

The same general pattern is observed during precipitation events. However, the large amount of 

water coming through the south lateral SD line during storm events prevents much of the 

backward flow of water over the sensor. Given the complexities of the sensor location, it is 

difficult to determine if there is any base flow input from the south lateral line. 

Figure 5c shows the relationship between volume and precipitation at MH356. The slope of the 

regression is 152,279 L/mm rain (r2

 = 0.912). Flow at MH356 is 21 percent of the modified flow 

at LS431. 

There were gaps in data collection at MH356 between April 21 and May 4, and between June 2 

and June 10. 

MH369. The flow sensor at MH369 was installed in a 1.52-meter (5-foot) diameter SD that 

serves as part of the lift station’s storage overflow in the south-central lateral line. During base 

Page 12 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

flow, water level at MH369 varied with the activation of the lift station. The lift station pump 

was activated when the water level reached 0.78 meter (2.6 feet). The level dropped to 0.44 

meter (1.5 feet) after the pump turned off. There was no negative flow of water over the sensor 

like that observed at MH356. 

During base flow, velocity readings were approximately 0.06 m/s (0.2 ft/s) when the lift station 

was activated. During storm flow, the water near the sensor was agitated due to input from an 

elevated SD line and from an upstream bend in the south-central SD line. As a result, velocity 

readings during storm flow were variable and frequently negative. Total flows could not be 

measured during storm events. 

When the flow sensor was installed, it was mistakenly believed the only input to MH369 were 

two 0.3-meter (1-foot) surface drains located 1.2 meters (4 feet) beneath the surface. On May 7, 

the flow sensor was moved from the 1.52-meter drain to the only one of these drains with 

stormwater flow. The intent was to measure at least a portion of flow entering MH369. 

The volume versus precipitation relationship at this location has a slope of 11,045 L/mm rain (r2

= 0.899). This slope is only 1.5 percent of the modified LS431 flow. This is much smaller than 

the expected amount of runoff from this area. Flow from the small drain at MH369 was not 

representative of total flow in the south-central SD line. Close inspection of the CAD files 

showed that the larger and deeper line where the sensor was originally installed was the correct 

location for flow through the south-central SD line. This location was not suitable for flow 

measurements due to the conditions noted above. 

None of the flow data from MH369 is considered usable. 

MH226. There were no major issues with data collection at MH226. Flow data spanning the 

entire time period were successfully measured. Maximum level readings were 0.21 meter (0.7 

feet) and velocity reached a maximum of 1 m/s (3 ft/s). Between precipitation events, level and 

velocity were slow to reach zero, although the impact this had on flow was negligible. 

The volume versus precipitation relationship is shown in Figure 5d. The slope is 63,569 L/mm 

rain (r2

 = 0.964). 

MH108. The most persistent issue encountered at MH108 during the preliminary stormwater 

sampling was errors in the velocity measurements while sampling (SAIC 2010a). Velocity 

readings would increase as the first flush of stormwater hit the sensor, and then remain elevated 

after the stormwater flow was reduced. This issue was present for Events 1 through 5. 

The problem was less severe, but not solved, for the expanded stormwater sampling. Flow data 

from Events 6 and 10 were impacted the most. As a precaution, flow from these two events has 

been calculated from the volume versus precipitation regression. Event 7 did not seem to be 

impacted by this problem. Events 8 and 9 had some issues with velocity, but the velocity profile 

was still a good match with the storm hydrograph. Flow from Events 7 through 9 is usable as 

measured. 

With the exception of the velocity measurement problems during sampling events, there were no 

issues at MH108. All measurements were successfully collected through the end of June. 

Maximum water levels at MH108 were close to 0.5 meter (1.5 feet), and maximum velocities 

September 2010 Page 13 
Interim Data Report Expanded Stormwater Sampling 

approached 0.9 m/s (2.95 ft/s). The slope of the relationship between volume and precipitation 

was 111,562 L/mm rain (r2

 = 0.940) (Figure 5e). 

CB423. There were no major issues with data collection at CB423. Data spanning the entire time 

period was successfully measured. Maximum level readings were 0.09 meter (0.3 feet) and 

velocity reached a maximum of 0.55 m/s (1.8 ft/s). As with MH226, level and velocity were slow 

to reach zero between precipitation events. 

Figure 5f shows the volume and precipitation regression for CB423. The slope is 8,335 L/mm 

rain (r2 = 0.919). CB423 drains the area around Building 3-380 and is the smallest area draining 

to the lift station. It represents about 1.2 percent of the total modified flow from the lift station. 

MH434. Flow data from storm events was not successfully measured at MH434. Tides entered 

MH434 with a frequency that made it difficult to isolate flows associated with precipitation 

events. There were a few instances where there was precipitation and no tide. During these times, 

level readings from the flow sensor did not exceed 0.04 meter (1.5 inches). By comparison, tidal 

depths ranged up to 0.5 meter (1.5 feet). 

3.1.4 Event Summaries 

The same precipitation criteria were applied to Storm Events 6 through 10 as for the preliminary 

stormwater sampling (SAIC 2010a). The goal of each storm event was to meet criteria 

established by Ecology’s Environmental Assessment Program’s (EAP) standard operating 

procedures (SOPs) for stormwater monitoring (Ecology 2009). All sample event figures are 

presented in Appendix B. 

A qualifying storm event was defined as follows: 

• At least 3.8 mm (0.15 inch) of rainfall; 

• Event duration of at least 5 hours; 

• No more than 1 mm (0.04 inch) of rainfall during the preceding 24 hours; 

• Sampling duration that includes at least 75% of the storm event hydrograph, or at least 

75% of the first 24 hours of the storm if the storm lasted more than 24 hours; 

• Collection of at least 10 sample aliquots, with a minimum volume of 200 mL. 

All sampled events had at least 3.8 mm of precipitation and lasted for at least 5 hours. For Events 

7 and 9, 4.6 mm (0.11 inch) and 2.8 mm (0.11 inch) fell in the preceding 24 hours, respectively. 

Less than 1 mm fell before all other events. Determination of storm hydrographs was difficult for 

many of the events due to the inconsistent nature of spring rainfall. For Event 8, the entire storm 

hydrograph was sampled. A period of at least 20 hours was sampled for all other events. Nine 

aliquots were sampled at LS431 for Event 10. A sufficient number of aliquots were collected for 

all other events. 

The only criteria for the baseflow sampling were to avoid precipitation and make sure enough 

aliquots were collected to be representative of the sampling period. At least ten aliquots were 

collected for each of the base flow events. During the first base flow sampling, a trace amount of 

precipitation fell during the last hour of sampling. During the second full base flow event, a trace 

amount of precipitation fell midway through sampling. 

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Expanded Stormwater Sampling Interim Data Report 

 

4.0 Chemistry Results 

This section presents and summarizes analytical results for the expanded stormwater sampling. 

Results from the preliminary stormwater sampling are included in the discussion as relevant. The 

particle size fractionation results and parking lot surface solids samples are summarized 

separately. Chemical data validation results are summarized in Section 5.0. 

4.1 Filtered Suspended Solids Sampling 

Filtered suspended solids sampling results from MH108 and LS431 are summarized in Tables 4 

and 5, respectively. Results from sampling of additional lateral lines are presented in Table 6. 

Results from the additional locations on the north lateral SD line are presented in Table 7. 

Included in each table are the mass of solids from each filter bag, the flow through each totalizer, 

and if available, the total volume of stormwater at each location. Laboratory data summaries are 

available in Appendix C.

4.1.1 Physical Parameters 

Two measures of filtered solids mass are included in the tables. “Total extracted solids” 

represents the dried mass of the sample filter (after wet weight splits were removed for grain size 

and metals) minus the pre-weighed mass of the filter. In other words, total extracted solids are 

the mass of material extracted for PCB Aroclor and dioxin/furan congener analysis. “Estimated 

total solids” represents the total extracted solids mass plus an assumed dry weight of the grain 

size and metals splits. 

The calculated TSS is the estimated total solids mass divided by flow through the totalizer. 

However, the filtration system design likely resulted in inflated totalizer flows relative to 

collected solids. One problem was the variable velocity of water through the filtration system 

over the course of an event. As solids were collected on the filter, the flow through the filter 

became restricted. The decrease in flow decreased the line velocity and may have resulted in the 

settling of some of the larger suspended solids prior to reaching the filter. 

A second problem was related to the seal between the filter bag and the top of the filter housing. 

A felt gasket on top of the filter bag formed a seal between the filter bag and the filter housing 

during sampling. As the filter bag collected solids, the pressure on the bag increased. It is 

possible that the pressure became high enough during sampling to separate the seal and bypass 

the filter. This allowed water to flow through the totalizer without contributing solids to the 

filter. TSS as measured by the filtration system should be used with reservations. Filtered solids 

and whole water TSS measurements are compared in Section 4.2. 

Because neither of these issues occurred until a sufficient amount of solids had accumulated on 

the filter, the physical and chemical data analyzed from the collected solids are believed to be 

representative of stormwater solids. 

Grain size analysis was conducted when sufficient material could be scraped from the filter bag. 

Eight samples each were analyzed from the storm events at MH108 and LS431, plus the two 

base flow events. There was no consistent particle size distribution at LS431. Events 4, 7, and 8 

September 2010 Page 15 
Interim Data Report Expanded Stormwater Sampling 

had percent fines at 97.4 percent, 99.6 percent, and 99.3 percent, respectively. In contrast, 

percent fines in Events 1, 2, 6, and 9 ranged between 13.8 percent and 65.9 percent. 

The particle size distribution at MH108 was more uniform across storm events. Percent fines for 

Events 1 through 6 and Events 8 and 9 ranged between 37.7 and 66.6 percent. Most of the coarse 

material for these events was in the sand fraction. Event 7 differed from the rest with 99.9 

percent fines. The particle size distribution between silt and clay was similar between LS431 and 

MH108 for Event 7. Both were near 66 percent silt and 33 percent clay. 

Percent fines for base flow events were expected to be high. Fines for Base Flow Event 1 (March 

20, 2010) at LS431 was 92.4 percent, and 99.9 percent at MH108 (February 23, 2010). Percent 

fines for Base Flow Event 2 at LS431 were 99.9 percent. Fines for Base Flow Event 2 at MH108 

were 57.9 percent, with 26.2 percent of the particle size distribution consisting of coarse sand. 

Grain size was measured in two other locations representing NBF drainages. Two samples were 

analyzed from MH434, containing 97.5 and 99 percent fines. Both events were tidally 

influenced, suggesting river water as the source of the fines. One sample was analyzed from 

CB423. It contained 81.7 percent fines and 17.2 percent sand. There was visible sand at the 

bottom of the catch basin at this location. 

Seven grain size samples from four locations were collected from the north lateral SD line 

locations. Percent fines ranged between 73.6 and 100 percent for all samples. 

4.1.2 Chemical Analysis 

Metals 

Metals results were compared to the Washington State Sediment Management Standards (SMS) 

numeric Sediment Quality Standards (SQS) and Cleanup Screening Levels (CSL) criteria 

(Washington Administrative Code [WAC] 173-204). PCBs and PAHs were compared to the 

lowest apparent effects threshold (LAET) and the second LAET (2LAET) (PTI 1988). The 

LAET and 2LAET are functionally equivalent to the SMS/CSL values, but are not organic 

carbon normalized. Collection of TOC data from the filters was not possible due to interference 

from the organic polypropylene filter bag. 

Metals were analyzed in all of the filtered solids samples collected as part of the expanded 

stormwater sampling. Silver and arsenic were frequently not detected. Of the detected 

concentrations of silver, only one exceeded the SQS/CSL. During Event 9 at CB165, silver 

concentrations were 160 milligrams per kilogram (mg/kg). Arsenic was detected in about half of 

the filtered solids samples. Undetected samples frequently exceeded the SQS and CSL criteria 

due to elevated reporting limits. Detected arsenic concentrations exceeded the criteria at MH369, 

MH133, and MH138 (Tables 4 through 7). 

Chromium and lead had one exceedance each. Chromium exceeded the CSL at MH133 during 

Event 10 with a concentration of 274 mg/kg. The only exceedance for lead occurred at MH108 

during Event 4 of the preliminary stormwater sampling. Copper exceeded the SQS/CSL criteria 

in a total of six samples. Five of these exceedances were from locations in the north lateral SD 

line. The only other exceedance was Event 10 at MH226 in the north central lateral line. 

Page 16 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

With the exception of one exceedance at LS431, all exceedances for mercury occurred in the 

north lateral line (Figure 6). MH133, CB173, and CB165 had the highest average concentrations. 

Both CB165 and CB173 had individual measurements of mercury over 10 mg/kg (Figure 6c). 

Average concentrations at MH152 and MH108 were also elevated at levels above 0.7 mg/kg. 

Unlike other locations in the north SD line, concentrations at MH178 and MH138 were below 

the SQS. Stormwater at MH178 enters from off site at the north end of the drainage. MH138 is at 

the downstream end of a small drainage within the north SD line. Concentrations at LS431 

averaged 0.4 ± 0.6 mg/kg. Combined concentrations at all remaining drainage lines averaged 

0.23 ± 0.09 mg/kg. 

Zinc and cadmium were detected at levels that exceed the SQS and CSL criteria at nearly all 

locations. The highest cadmium concentrations were 78 mg/kg and 102 mg/kg from Events 9 and 

10 at CB133, respectively. These were the only two samples collected at CB133. Measured 

concentrations of cadmium at all other sites ranged between 3.0 and 31.2 mg/kg. Zinc exceeded 

the CSL in at least one sample at all locations except MH369 and MH178. 

Base flow filtered solids samples were analyzed for metals at MH108, LS431, and CB173. At 

CB173, base flow concentrations were comparable to those found during storm events. At LS431 

and MH108, base flow concentrations were lower than during storm events with two exceptions. 

The highest lead concentration at LS431 was measured during Base Flow Event 1. The second 

highest mercury concentration at MH108 (2.29 mg/kg) was also measured during Base Flow 

Event 1. 

Many of the metals show a pattern where concentrations are lowest at LS431. This is true for 

cadmium, chromium, copper, lead, and zinc. It is not clear what could have resulted in higher 

concentrations in the individual lateral lines than in the combined output. Though not directly 

comparable, the concentrations of metals from samples collected for size fractionation from the 

lift station vault (Section 4.3) do appear to be higher than concentrations from the downstream 

side of the lift station. 

PCBs 

Total PCB concentrations were reported as micrograms (μg)/filter and converted to μg/kg by 

dividing by the mass of total extracted solids. Total PCBs were calculated as the sum of detected 

Aroclors 1221, 1232, 1242, 1016, 1248, 1254, and 1260. Total PCBs exceeded the LAET or 

2LAET in all samples with the exception of Event 9 at MH178. 

Average total PCB concentrations at LS431 over 11 events (plus Event 9b) were 1.3 ± 0.8 

mg/kg, compared with 6.4 ± 5.9 mg/kg at MH108. MH108 had the highest average PCB 

concentration of the major lateral lines. Total PCBs exceeded the 2LAET in every sample 

collected at MH108. Average concentrations in the other three lateral SD lines were closer to 0.5 

mg/kg (Figure 7b). 

The base flow samples had some of the highest PCB concentrations measured in this study 

(Figure 7a and 7c). Base Flow Event 1 and 2 at MH108 had concentrations of 25 mg/kg and 22 

mg/kg, respectively. One base flow sample was collected at CB173. The concentration in this 

sample was 43 mg/kg. There is some question as to whether this sample was representative of 

base flow or stormwater holdover. The structure CB173 is lower than the exiting SD. Boeing has 

observed no base flow entering the structure from upstream, but has indicated that base flow 

September 2010 Page 17 
Interim Data Report Expanded Stormwater Sampling 

from downstream may be flowing into this location. Two base flow samples were also collected 

at LS431. Both samples fell within the range of concentrations measured during the storm 

events. These results indicate that base flow is responsible for higher PCB concentrations in the 

north lateral SD line, but that these higher concentrations do not have a significant impact at 

LS431, possibly due to dilution with cleaner base flow from other areas of the site. 

There were also differences in the Aroclor distribution between storm event and base flow 

samples. Aroclors 1254 and 1260 were most commonly detected in the storm events. Aroclors 

1242 and 1254 were detected in the base flow samples. 

PCBs in the north lateral SD line were higher than in other locations. The locations with the 

highest concentrations were those on the main branch of the north lateral SD line. Concentrations 

at CB165 averaged 3.8 ± 3.2 mg/kg over the course of three events, while concentrations at 

CB173 averaged 14.2 ± 3.7 mg/kg. MH178 is located next to CB173. However, unlike CB173, 

much of the stormwater flow at MH178 comes from off site. Concentrations at MH178 were 

over an order of magnitude lower than those at CB173 (Table 7, Figure 7c). 

There is a small positive correlation (r2

 = 0.666) between MH108 and LS431 PCB 

concentrations, suggesting that elevated concentrations at LS431 are influenced by MH108. 

While there is no overall correlation between rainfall (stormwater volume) and concentration, the 

two events with the lowest rainfall at both MH108 and LS431 had the highest PCB 

concentrations. 

PAHs 

PAHs were measured in filters from Events 3, 6, 7, 8, and 10. Total high molecular weight PAHs 

(HPAHs) were calculated as the sum of the detected compounds fluoranthene, pyrene, 

benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, 

indeno(1,2,3-cd)pyrene, dibenz(a,h)anthracene, and benzo(g,h,i)perylene. Total low molecular 

weight PAHs (LPAHs) are the sum of detected compounds of naphthalene, acenaphthylene, 

acenapthene, fluorene, phenanthrene, and anthracene. 

Phenanthrene frequently exceeded the LAET or 2LAET criteria. Other LPAHs were often not 

detected. Total LPAH concentrations were typically about one-tenth as high as total HPAH 

concentrations. 

Total HPAH concentrations were variable between LS431 and MH108 (Figure 8a). However, the 

average concentration of HPAH across the five events was similar at both locations, at 17.8 

mg/kg for MH108 and 18.8 mg/kg for LS431. MH369 had the lowest concentrations found in the 

main lateral lines, while MH226 and MH356 had the highest (Figure 8b). 

Locations in the north lateral SD line were just as variable. HPAH ranged between 3.8 and 7.0 

mg/kg at CB173 and CB165. The concentration from the lone sample collected from MH133 

was 97.8 mg/kg. 

Dioxins/Furans 

Dioxin/furan congeners were analyzed from Events 2, 4, and 9, with select samples analyzed 

from Event 9b. The first base flow sample from MH108 was also analyzed for dioxin/furan 

congeners. Results are pending from Base Flow Event 2 for LS431, MH108, and CB173. 

Page 18 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

Concentrations of each congener were normalized to the toxicity of 2,3,7,8-TCDD 

(tetrachlorodibenzodioxin) using toxic equivalency factors (TEFs) updated by the World Health 

Organization (WHO) in 2005 (Van den Berg et al. 2006). The toxic equivalent quotient (TEQ) is 

equal to the sum of the concentrations of individual congeners multiplied by their TEF. Though 

all congeners were detected, TEQ values are reported as 0 and 1⁄2 times the method detection 

limits. 

TEQ concentrations at both LS431 and MH108 were much higher for Events 2 and 4 than for 

Event 9. At MH108, Event 2 and 4 concentrations were 144 and 157 picograms per gram (pg/g) 

TEQ, respectively. For Event 9, the concentration was 10.7 pg/g TEQ. There was a similar 

decrease at LS431. 

All locations were sampled as part of Event 9 or 9b. Of the lateral line locations, MH356 was 

most similar to the lift station with a concentration of 6.57 pg TEQ/g. MH369 and MH226 had 

concentrations of 17.3 and 44.6 pg TEQ/g, respectively. As with the metals, it is not clear why 

the dioxin/furan concentration at LS431 is lower than those at the other lateral lines. MH343 in 

the parking lot drainage had a TEQ of 65.5 pg/g. 

Samples from the north drain line during Event 9 ranged from 14.2 to 48.9 pg/g TEQ. There is 

no clear pattern to the concentrations (Table 7). 

4.2 Whole Water Sampling 

Whole water sampling results from MH108 and LS431 are summarized in Tables 9 and 10, 

respectively. Concentrations are compared to the lower of the chronic marine water or freshwater 

criteria (WAC 173-201A-240). Contaminants lacking marine or freshwater criteria are compared 

to the human health water quality criteria for consumption of organisms (HHO) (USEPA 2006). 

Laboratory data summaries are presented in Appendix C. 

4.2.1 Physical Parameters 

Conventional parameters including pH, alkalinity, hardness, TSS, chloride, nitrate, sulfate, DOC, 

and TOC were measured in each of the whole water samples. pH was consistently higher at 

LS431, although all events at both locations ranged between pH values of 6.7 and 7.7. 

Correspondingly, alkalinity was also higher at LS431. At both locations, alkalinity was highest 

during the two base flow samples. Chloride varied over the course of 10 events, particularly at 

LS431. There was no relationship between chloride and tidal influx into LS431 (Section 3.1.2). 

TOC ranged between 6.5 and 21.2 mg/L and averaged 8.7 mg/L at LS431. TOC ranged between 

4.3 and 31.8 mg/L and averaged 7.2 mg/L at MH108. 

Figure 9 presents whole water TSS for all storm and base flow events at LS431 and MH108. 

Calculated TSS from the filtered solids are included for comparison. As stated, TSS from the 

filtered solids collection are biased low due to excess water flow through the totalizer (Section 

4.1.1). Given the problems with calculating TSS from the filtration system, whole water TSS are 

considered more representative of stormwater conditions. Sampling and analytical methods 

support this. The whole water samples analyzed for TSS were volume weighted over the course 

of a storm event and were sampled using a consistent pump flow and velocity. In the laboratory, 

a known volume of water was passed through a 0.45-micron filter. 

September 2010 Page 19 
Interim Data Report Expanded Stormwater Sampling 

The relationship between the whole water and filtered solids TSS at LS431 and MH108 can 

hopefully be extrapolated to the sampling locations in the other drainage basins to allow for 

better loading estimates. 

Average TSS concentrations were 27.5 mg/L at LS431 and 24.2 mg/L at MH108. There was 

some variability around these averages. Concentrations ranged between 3.3 and 75.9 mg/L. 

There was a positive correlation between TSS at the two locations (r2 = 0.678). 

4.2.2 Chemical Analysis 

Cadmium, copper, lead, and zinc were all detected at levels above the marine water criteria 

(MWC). Copper had more exceedances than the other metals. Average total copper 

concentrations were 8.5 μg/L at LS431 and 15.7 μg/L at MH108 for all 10 storm events. Base 

flow concentrations were lower than those for storm events, although total copper did exceed the 

MWC for Base Flow Event 2 at MH108. Dissolved copper concentrations were usually about 

one half that of total copper. 

Total cadmium was detected above the MWC in Event 6 at MH108 and Base Flow Event 1 at 

both LS431 and MH108. Total lead exceeded the MWC in one storm event at LS431, and three 

at MH108. Both cadmium and lead were rarely detected in the dissolved phase. Total zinc was 

detected at the highest concentration in the whole water samples. There were two exceedances at 

LS431 and four at MH108. Base flow concentrations of zinc were four to seven times lower than 

those found in stormwater. 

Mercury was analyzed in all samples but never detected. The reporting limits for mercury are 

higher than the freshwater criteria (FC) of 0.012 μg/L. 

Total PCB concentrations for each event are presented in Figure 10. Total PCBs from filtered 

solids are included for comparison. PCBs were detected in all samples analyzed from MH108, 

with concentrations ranging from 0.016 to 0.145 μg/L for the stormwater events. Base flow 

concentrations were higher, at 0.22 μg/L and 0.27 μg/L for Base Flow Events 1 and 2, 

respectively. 

Total PCB concentrations at LS431 were lower than MH108. PCBs were undetected in Events 1, 

2, and 10. Event 4 was below the FC. All other events exceeded the criteria. Using the reporting 

limit in place of undetected values, the average PCB concentration at LS431 was 0.029 for 

stormwater events. The concentrations from the base flow samples were lower, at 0.014 and 

0.016 μg/L. The conclusion drawn from the base flow samples for filtered solids is the same for 

whole water: base flow is responsible for higher concentrations in the north drain line, with little 

impact at the lift station. 

There is no direct correlation between PCBs in filtered solids and in whole water at either 

location (Figure 10). If whole water PCBs are normalized to mg/kg using the TSS, there is a 

slight correlation at MH108 (r2

 = 0.553) for all 10 storm events. The same correlation is not 

present at LS431. TSS normalized whole water concentrations are similar in magnitude to total 

solids concentrations at both locations. 

HPAHs were detected more frequently than LPAHs. Several HPAHs, including 

benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, 

indeno(1,2,3-cd)pyrene, and dibenz(a,h)anthracene, have a water quality criterion (HHO) of 

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Expanded Stormwater Sampling Interim Data Report 

 

0.018 μg/L. These compounds frequently exceeded the HHO at LS431. HPAH concentrations 

were typically higher at LS431. The HHO criterion was exceeded with about half this frequency 

at MH108 (Tables 9 and 10). 

Average HPAH was 2.1 μg/L at LS431 and 1.9 μg/L at MH108. Base flow concentrations were 

an order of magnitude lower. PAHs in stormwater are likely a result of surface runoff. 

Additional SVOCs were analyzed but seldom detected. Bis(2-ethylhexyl)phthalate was detected 

at levels that exceeded the HHO criteria during Events 4 and 7 at MH108. Additional phthalates, 

including di-n-octyl phthalate, diethylphthalate, and di-n-butyl phthalate, were detected at both 

locations. 

VOCs detected as part of the preliminary stormwater sampling were also present in Events 6 

through 10. Methylene chloride, acetone, and 2-butanone were detected in most samples. Each of 

these VOCs was detected in at least one of the base flow samples at each location at 

concentrations comparable to the stormwater samples. 

4.3 Particle Size Fractionation 

Results of the particle size fractionation analysis are described in the Slip 4 Sediment 

Recontamination Modeling Report (SAIC 2010c). Briefly, the highest total PCB concentrations 

were found in the finest (<63 μm) and coarsest (>500 μm) fractions in all three samples. 

Concentrations in both of these fractions were similar, ranging from 7.7 to 13.6 mg/kg. The 

concentrations in the medium two size fractions were 20 to 50 percent of these values (Table 10). 

The metals cadmium, chromium, copper, lead, mercury, and zinc were detected in all size 

fractions from Composite 1. The highest concentrations of metals were found in the fine fraction 

and the second highest concentrations in the coarsest fraction. 

Both LPAHs and HPAHs were detected in all fractions analyzed. Again, the greatest 

concentrations were in the fine and coarse fractions. In Composite 4, the coarsest fraction (>500 

μm) contained LPAHs and HPAHs an order of magnitude higher than other fractions. 

The percentage of each grain size fraction in the total composites is unknown. As such, sample 

concentrations cannot be reconstructed. This prevents a direct comparison of filtered solids 

between the lift station vault and downstream side of the lift station. 

4.4 Surface Solids Samples 

Parking lot sweep samples are summarized in Table 12. Grain size analysis was conducted on 

each of the six samples. Total fines ranged from 7.9 to 17.2 percent. Total sand was the dominant 

fraction in all samples, falling in the narrow range of 75.7 to 84.2 percent. The sweep samples 

consist of a much coarser grain size distribution than the TSS samples collected by the filter 

bags. 

PCBs, metals, and PAHs were analyzed in each of the samples. Concentrations were similar 

across the six locations for all analytes. The results were compared to the LAET and 2LAET 

criteria on the assumption that a portion of these solids may end up in the SD system (Table 12). 

September 2010 Page 21 
Interim Data Report Expanded Stormwater Sampling 

Aroclors 1254 and 1260 were detected at all locations, and Aroclor 1248 was detected at four of 

the locations. Total PCB concentrations ranged between 0.116 and 0.34 mg/kg, with five of the 

locations exceeding the LAET. 

Concentrations of most metals were lower than those found in the filtered solids. Lead and 

chromium were exceptions. Concentrations of these two metals were toward the high end of the 

range of concentrations from the filtered solids. PAH concentrations were lower than in the 

filtered solids. Total HPAH ranged between 1.02 and 6.34 mg/kg. None of the PAH or metal 

concentrations exceeded the LAET. 

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Expanded Stormwater Sampling Interim Data Report 

 

5.0 Quality Assurance/Quality Control 

A Level IV data validation was requested on all data. The data validation report is still pending. 

All tables will be updated with qualified values upon receipt of the report. 

September 2010 Page 23 
Interim Data Report Expanded Stormwater Sampling 

6.0 Summary 

Expanded stormwater sampling was a continuation of the preliminary sampling at NBF-GTSP. 

As part of this effort, the collection of filtered suspended solids and whole water samples 

continued at LS431 and MH108 for five more storm events and two base flow events. Sampling 

of filtered suspended solids was added at the downstream end of the other lateral SD lines, and at 

select locations in the north SD line. Continuous flow measurements were collected at the lift 

station and at each of the onsite drainages. 

Sufficient flow measurements were collected from LS431, MH108, MH226, CB423, and 

MH356 to characterize the relationship between precipitation amount and the volume of 

stormwater runoff for each location. In addition, the presence of the flow meters in each lateral 

line helped to determine the extent of the storage capacity of the lift station. Both MH369 and 

MH356 were affected by the activation of the lift station pumps. 

Concentrations of metals in filtered suspended solids were variable. Cadmium and zinc exceeded 

the LAET criteria at nearly all locations, while mercury concentrations were highest in the north 

lateral SD line. Concentrations of most metals in base flow were lower than the stormwater 

samples. 

PCB concentrations for both filtered solids and whole water were highest in the north lateral SD 

line. Base flow concentrations from the north SD line had higher concentrations than the storm 

events. However, base flow concentrations at LS431 were within the same range as the storm 

event samples, suggesting the inflow of PCBs in the north drain line were not enough to alter 

base flow concentrations at the lift station. The Aroclor distribution of PCBs varied between 

storm events and base flow. Aroclors 1254 and 1260 were most commonly detected in 

stormwater, while Aroclors 1242 and 1254 were most common in base flow. 

Additional parameters were analyzed in the whole water samples. Phthalates were detected 

occasionally, but only bis(2-ethylhexyl)phthalate exceeded the HHO criteria. Methylene 

chloride, acetone, and 2-butanone continued to be detected in whole water samples. Base flow 

concentrations of these VOC were similar to the storm event concentrations. 

Filtered solids samples from MH434 were not representative of parking lot runoff due to tidal 

intrusion. Six surface sweep samples were collected to determine the potential of the parking lot 

as a source to Slip 4. PCBs exceeded the LAET in five of the samples, but concentrations were 

lower than those in the lateral SD lines. No metals or PAHs exceeded the LAET criteria. 

Page 24 September 2010 
Expanded Stormwater Sampling Interim Data Report 

 

7.0 References 

Ecology. 2009. Standard Operating Procedure for Automatic Sampling for Stormwater 

Monitoring. Washington State Department of Ecology. Draft Version 1.0. 

Landau. 2010. Revised Work Plan, Storm Drain System Catch Basin, Manhole, and Oil/Water 

Separator Sampling and Storm Drain System Cleaning, North Boeing Field, Seattle, 

Washington. Prepared for The Boeing Company by Landau Associates, Edmonds, WA. 

March 26, 2010. 

PTI. 1988. Sediment Quality Values Refinement: 1988 Update and Evaluation of Puget Sound 

AET. Volume I. Final Report. Prepared for Tetra Tech, Inc., Bellevue, WA, and the U.S. 

Environmental Protection Agency, Region 10, Seattle, WA. Prepared by PTI 

Environmental Services, Bellevue, WA. 

SAIC. 2009a. North Boeing Field/Georgetown Steam Plant Site Remedial Investigation/ 

Feasibility Study: Sampling and Analysis Plan and Quality Assurance Project Plan for 

Preliminary Stormwater and Filtered Suspended Solids Sampling. Prepared for Toxics 

Cleanup Program, Northwest Regional Office, Washington State Department of Ecology, 

by SAIC, Bothell, WA. August 2009. 

SAIC. 2009b. North Boeing Field and Georgetown Steam Plant, Supplemental Report: 

Summary of Existing Information and Identification of Data Gaps. Prepared for Toxics 

Cleanup Program, Northwest Regional Office, Washington State Department of Ecology, 

by SAIC, Bothell, WA. August 2009. 

SAIC. 2010a. North Boeing Field/Georgetown Steam Plant Site Remedial Investigation/ 

Feasibility Study: Preliminary Stormwater Sampling Interim Data Report. Prepared for 

Toxics Cleanup Program, Northwest Regional Office, Washington State Department of 

Ecology, by SAIC, Bothell, WA. May 2010. 

SAIC. 2010b. North Boeing Field/Georgetown Steam Plant Site Remedial Investigation/ 

Feasibility Study: Work Plan and SAP/QAPP Addendum Expanded Stormwater 

Monitoring. Prepared for Toxics Cleanup Program, Northwest Regional Office, 

Washington State Department of Ecology, by SAIC, Bothell, WA. March 2010. 

SAIC. 2010c. North Boeing Field/Georgetown Steam Plant Site Remedial Investigation/ 

Feasibility Study: Slip 4 Sediment Recontamination Modeling Report. Prepared for 

Toxics Cleanup Program, Northwest Regional Office, Washington State Department of 

Ecology, by SAIC, Bothell, WA. July 2010. 

USEPA. 2006. National Recommended Water Quality Criteria. Prepared by United States 

Environmental Protection Agency, Office of Water, Office of Science and Technology. 

2006. 

September 2010 Page 25 
Interim Data Report Expanded Stormwater Sampling 

Page 26 September 2010 

Van den Berg, M., L.S. Bimbaum, M. Denison, M. De Vito, W. Farland, M. Feeley, H. Fiedler, 

H. Hakansson, A. Hanberg, L. Haws, M. Rose, S. Safe, D. Schrenk, C. Tohyama, A. 

Tritscher, J. Tuomisto, M. Tysklind, N. Walker, and R. Peterson. 2006. The 2005 World 

Health Organization Re-Evaluation of Human and Mammalian Toxic Equivalency 

Factors for Dioxins and Dioxin-like Compounds. Prepared for the World Health 

Organization (WHO). ToxSci Advance Access published July 7, 2006. Published by 

Oxford University Press on behalf of the Society of Toxicology.