# Sampling Episode Report Cruise Ship Plume Dilution Study Skagway, Alaska

U.S. Environmental Protection Agency

Oceans and Coastal Protection Division Office of Wetlands, Oceans, and Watersheds

Office of Water 1200 Pennsylvania Avenue, NW Washington, D.C. 20460

May 18, 2009ACKNOWLEDGMENT AND DISCLAIMER

This report was prepared by the Oceans and Coastal Protection Divisi on of the Office of Wetlands, Oceans, and Watersheds of the U.S. Environmental Protection Agency. Neither the United States Government nor any of its employees, contractors, subc ontractors, or their employees make any warrant, expressed or implied, or assume any legal liability or responsibility for any third party’s use of, or the results of such use, any information, apparatus, product, or process discussed in this report.

The primary contact regarding questions or comments on this document is:

Dr. Brian Rappoli U.S. Environmental Protection Agency Oceans and Coastal Protection Division, OWOW (4504T) 1200 Pennsylvania Avenue, NW Washington, DC 20460

(202) 566-1548 (telephone) (202) 566-1546 (fax) rappoli.brian@epa.govi TABLE OF CONTENTS

Page

E XECUTIVE S UMMARY .................................................................................................................... iv

1. I NTRODUCTION .................................................................................................................1-1

2. D ESCRIPTION OF S ELECTED C RUISE V ESSELS ...................................................................2-1

3. D ATA C OLLECTION M ETHODOLOGY .................................................................................3-1 3.1 Pre-Sampling Activities.......................................................................................3-1 3.2 Sampling Schedule...............................................................................................3-1 3.3 Dye Injection Methodology .................................................................................3-1 3.4 Plume Monitoring Methodology..........................................................................3-2
3.5 Current and Weather Measurements....................................................................3-5

4. R ESULTS ...........................................................................................................................4-1 4.1 Discharge Plumes.................................................................................................4-1 4.2 Transect Water Quality Data ...............................................................................4-5
4.3 Current Measurements and Weather Data ...........................................................4-5

5. D ATA Q UALITY .................................................................................................................5-1 5.1 Quality Assurance Assessment of Key Plume Dilution Study
Measurements ......................................................................................................5-1 5.2 Quality Assurance Assessment of Non-Key Plume Dilution Study
Measurements ......................................................................................................5-2

Appendix A DILUTION STUD Y TRANSECTS BY SHIP

Appendix B DISCHARGE PLUME DYE CONCENTRATIONS, TEMPERATURE, CONDUCTIVITY, DEPTH, TURBIDITY, AND SALINITY

Appendix C SKAGWAY HARBOR DEPTH PROFILES

Appendix D CURRENT MEASUREMENTS

Appendix E SKAGWAY TIDE TABLE

Appendix F MANUAL FIELD LOGS

Appendix G DISCHARGE FLOW MEASUREMENTS

Appendix H WEATHER DATA

Appendix I OSV BOLD SURVEY PLANTABLE OF CONTENTS (Continued)

ii Appendix J QUALITY ASSURANCE PROJECT PLAN FOR SUPPORT FOR OSV BOLD
SURVEY OF LARGE CRUISE SHIP WASTEWATER IMPACTS IN
ALASKAN WATERSiii LIST OF TABLES

Page

Table 2-1. Characteristics of Cruise Vessels That Participated in 2008 Plume Dilution Study, Skagway Alaska............................................................................................................... 2-1

Table 3-1. Sampling Schedule ................................................................................................... .. 3-1

Table 3-2. Target Discharge Rhodamine WT Dye Concentrations by Cruise Vessel................. 3-2

LIST OF FIGURES

Page

3-1 Sea-Bird SBE-19 CTD Sensor with Integrated SCUFA® Fluorometer.......................... 3-3

3-2 Rigid Inflatable Boat...................................................................................................... .. 3-3

3-3 Orientation of Arc Transects............................................................................................ 3-5

4-1 Profile of Arc Transect Results for Ryndam .................................................................... 4-2

4-2 Profile of Arc Transect Results for Celebrity Millennium ............................................... 4-3

4-3 Profile of Arc Transect Results for Norwegian Star ........................................................ 4-4

4-4 Profile of Arc Transect Results for Volendam ................................................................. 4-5iv E XECUTIVE S UMMARY

Sampling Episode Report for Cruise Ship Plume Dilution Study

This Sampling Episode Report describes a plume dilution study conducted under the
direction of the U.S. Environm ental Protection Agency (EPA) in collaboration with the Alaska Department of Environmental C onservation (ADEC). This study, part of a survey conducted in Alaska by EPA’s Ocean Survey Vessel Bold in July 2008, was designed to characterize nearfield cruise ship discharge plumes from six cr uise vessels while they were docked in Skagway Harbor, Alaska. Sampled vessels represented th ree cruise lines and a variety of advanced
wastewater treatment system types, wastewater discharge flow rates, discharge port sizes, and port depths below the waterline. This st udy was conducted as a continuation of EPA’s assessment of standards for sewage and graywater discharges from large cruise ships operating
in Alaska.

Using in situ measurements of Rhodamine WT dye in the effluent plume, the survey team determined the location and concentration of each vessel’s treated sewage and graywater discharge plume. A metering pump injected Rhodamine WT dye into the discharge line upstream of the discharge port, with a ta rget dye discharge concentration of 700 μ g/L (ppb). Dye concentrations in the resulting discharge plume we re measured using a submersible fluorometer. Additional parameters (temperatu re, conductivity, depth, turbidity, and salinity) were measured simultaneously with plume discharge dye concen tration, while manual notations of distance and location from the discharge port were made. Performing transects for plume characterization required approximately two hours per ship, with one ship tested per day. Measurements of the harbor current in the vicinity of the discharge plumes were collected using magnetic current meters. Dye concentrations in the discharge plume were found to decrease by a factor that ranged from approximately 40 to 90, depending upon ship, at a distance of 15 meters from the discharge port.1-1 1. I NTRODUCTION

This Sampling Episode Report describes samplin g and analysis activities to characterize graywater and sewage discharge pl umes from six cruise vessels ( Star Princess

, Coral Princess

, Ryndam

, Celebrity Millennium

, Norwegian Star , and Volendam ) discharging at port in Skagway Harbor, Alaska. This study, which was conducted from July 7 through July 17, 2008, is a
collaboration between EPA’s Oceans and Co astal Protection Division and the Alaska Department of Environmental Conservation (ADEC). This sa mpling study was partially funded via an interagency agreement between EPA and ADEC.

This study was part of a survey conducte d in Alaska by EPA’s Ocean Survey Vessel Bold and is a continuation of EPA’s assessment of the need for additional standards for sewage and graywater discharges from large cruise ships operating in Alaska under the “Certain Alaskan Cruise Ship Operations” law (also known as “Title XIV”; 33 USC 1901 Note). The data and information gathered through this sampling episode were collected using EPA’s authority under
Section 308 of the Clean Water Act, as also provided by Titl e XIV. The cruise lines participating in the study voluntar ily provided information and data gathered for and represented in this report, notwithstanding the above authority, in the in terest of research for the improvement of wastewater treatment standards.

This plume dilution study was designed to provide information on near-field cruise ship treated sewage and graywater effluent discharge plume characteristics in harbor waters. The study will also provide preliminary information on whether these plumes behave as predicted by modeling performed by ADEC (Asse ssment of Cruise Ship and Ferry Wastewater Impacts in Alaska, 2004). ADEC used EPA’s Visual Plumes model system 1 to simulate the dilution of discharges from both large and small vessels. ADEC’s estimated dilution factor for initial dilution of discharges from stati onary cruise ships in Skagway dur ing a neap tide ranged from 5 to 60. The objectives of this study were to (1) determine the effluent d ilution characteristics of discharges from stationary cruise ships; (2) tr ack the near-field mixing dynamics of the effluent plume; and (3) provide information that can be used to validate the modeling studies (see Survey Plan, Appendix I).

Other sampling programs supporting EPA’s assessment of cruise ship wastewater discharge standards in Alaska include two onboard sampling programs, conducted during the 2004 and 2005 Alaska cruise seasons, that fo cused on characterizing pollutants found in wastewater (graywater and sewa ge) onboard cruise vessels and ev aluating the performance of the advanced wastewater treatment systems. The results of these sampling programs can be found
on EPA’s website at www.epa.gov/owow/oceans/cruise_ships/results.html

.

Section 2 of this report descri bes the cruise vessels selected to participate in this study.
Section 3 describes the data co llection methodology. S ection 4 presents a brief summary of the results. Section 5 provides a qual ity assurance assessment of the study.

1 EPA’s Visual Plumes model system is a Windows-based software application for simu lating surface water jets and plumes. http://www.epa.gov/ceampubl/swater/vplume/2-1 2. D ESCRIPTION OF S ELECTED C RUISE V ESSELS

EPA selected the following six cruise vessels to participate in this plume dilution study:

• Star Princess;

• Coral Princess;

• Ryndam

• Celebrity Millennium;

• Norwegian Star; and

• Volendam

.

The vessels participating in the survey represente d three cruise lines and a variety of wastewater treatment system types, wastewater discharge flow ra tes, discharge port sizes, and port depths below the waterline. Each of the participating vessels operates an advanced wastewater treatment system to treat combined graywater and sewage. Table 2-1 presents th e characteristics of the cruise vessels selected to participate in this study.

Table 2-1. Characteristics of Cruise Vessels That Participated in 2008 Plume Dilution Study, Skagway Alaska

Cruise Vessel (Parent Company) Advanced
Wastewater
Treatment System Type Discharge
Flow Rate (m3/hour) Discharge
Port
Outer
Diameter (cm) Discharge Port Depth
Below
Waterline (m) Discharge Location

Star Princess (Carnival Corp.) Hamworthy 25.5 20.3 2.5 (estimated) Midship, Port

Coral Princess (Carnival Corp.) Hamworthy 25 20.3 4 Midship, Starboard

Ryndam (Carnival Corp.) Zenon 23 11.4 5 to 5.5 Midship, Port

Celebrity Millennium (Royal Caribbean Cruises, Ltd.) Hydroxyl 22 27.3 5 Midship, Port

Norwegian Star (Norwegian Cruise Line) Scanship 35 16.8 4.6 Midship, Starboard

Volendam (Carnival Corp.) Zenon 36 11.4 6 Midship, Port3-1 3. D ATA C OLLECTION M ETHODOLOGY

3.1 Pre-Sampling Activities

Visits to each of the six ships were conducte d during the week prior to the start of the sampling episode. Visits were made to establis h ship contacts, communications, and safety and emergency procedures, and to inspect sa mpling ports and associated fittings.

3.2 Sampling Schedule

Discharge plumes from six different cruise ships were monitored per the schedule in Table 3-1. Only one plume dilution study was conducted per day.

Table 3-1. Sampling Schedule

Cruise Vessel Date of Study Times of Study Skagway Pier

Star Princess July 10, 2008 1025 to 1230 Railway

Coral Princess July 11, 2008 1040 to 1245 Railway

Ryndam July 12, 2008 1025 to 1205 Railway

Celebrity Millennium * July 15, 2008 0950 to 1135 Railway

Norwegian Star * July 16, 2008 1000 to 1145 Ore

Volendam July 17, 2008 1005 to 1140 Broadway
* Trial testing was also conducted on the Celebrity Millennium on July 7, 2008, and the Norwegian Star on July 9, 2008, to refine sample collection methodology.

3.3 Dye Injection Methodology

Metering pumps (Series 2001HEC-30 Variab le Speed Peristaltic Pump, Flomotion Systems) were used to inject Rhodamine WT dye (Rhodamine WT Liquid, ORCO Organic Dyestuffs Corporation) into the cruise ships’ treated sewage and graywater discharge. The pumps were installed downstream of the advan ced wastewater treatment system, but as far upstream of the discharge port as possible so that multiple pipe bends and fittings provided thorough mixing of the dye.

Strap-on ultrasonic flow meters (BE 6000 U ltrasonic Flow Meter, Flomotion Systems) were installed on the discharge pi ping to record discharge rate s (presented in Appendix G). Measured discharge rates were multiplied by the known Rhodamine WT dye feed stock concentration to calculate and adjust discha rge dye concentration to attain the target concentration (discussed below). Discharge dy e concentration also was measured directly on three cruise vessels ( Celebrity Millennium

, Norwegian Star , and Volendam ) using a fluorescence sensor with a flow-through cell (SCUFA®, Turner Designs) insta lled on the discharge piping as close as possible to the discha rge port. While the sh ipboard survey team was able to monitor discharge dye concentration via laptop computer connected to the SCUFA® sensor, it was not possible to electronically log th ese data. Therefore, the survey team kept manual logs of discharge dye concentrations. Tables F-1 th rough F-4 of Appendix F contain the raw data obtained from the fluorometer (see Section 5.1).3-2 Trial dilution studi es conducted on the Celebrity Millennium and the Norwegian Star revealed that the originally planned target di scharge dye concentrati on of 100 ppb (see Survey Plan, Appendix I) was too low to be detected outside the cruise ve ssel (see Section 5.1, Accuracy and Calibration). Therefore, the target di scharge Rhodamine WT dye concentration was increased to 700 ppb for most transects (Table 3- 2). Target dye concentration was decreased during the Star Princess study because the plume was visible on the surface of the water (most likely because of the relatively shallow discharge port; see Table 2-1); this was the only vessel where the plume was visible on the surface of the wa ter. Target dye concentration was increased during the Coral Princess study because the highly intermittent nature of the discharge and strong water currents made plume de tection difficult (see Section 4.1).

Table 3-2. Target Discharge Rhodamine WT Dye Concentrations by Cruise Vessel

Cruise Vessel Discharge Rhodamine WT Dye Concentration (ppb)

Star Princess 700 (cast 4), then 420 (casts 5 through 11)

Coral Princess 700 (casts 2 through start of 5), 875 (portion of cast 5), 1,050 (end of cast 5 through cast 7)

Ryndam 700
Celebrity Millennium 700

Norwegian Star 700

Volendam 700

Discharge dye concentrations are the produc t of the known initial dye concentration, dye injection rate, and discharge flow rate. While the initial dye injection concentration and dye injection rate were constant (with the exception of the Coral Princess ; see Section 4.1), discharge flow rates varied, resu lting in variability of the disc harge dye concentration. Any analysis of the data collected in this study should consider this variability when calculating nearfield discharge plume dilution.

On four cruise vessels, temperature, turbidit y, and pH of the treated effluent also were recorded from the ship’s wastewater treatmen t control panel. Thes e data are provided in Appendix F. Similar data were not available for the remaining two ships.

3.4 Plume Monitoring Methodology

Dye was injected into the treated sewage and graywater discharge for approximately two hours on each cruise vessel. During that time, dye concentrations in the water outside the cruise vessel were measured to determine near-field pl ume dilution after discharg e (the cruise vessels all were positioned so that the discharge ports f aced the harbor and not th e piers). Prior to dye injection, measurements were taken of background fluorescence concentrations in the water. These measurements verified that no backgroun d seawater fluorescence was detected above the detection limit of fluorometer, which was appr oximately 1.6 ppb. For most ships, a salinity depth profile also was performed to locate the halocline prior to dye injection.

Dye concentrations were measured using an in situ fluorometer (SCUFA®, Turner Designs) integrated into a Sea-Bird SBE-19 c onductivity, temperature, and depth (CTD) sensor package (Sea-Bird SBE-19, Sea-Bird Electronics, Inc.) (Figure 3-1). This sampling array wasdeployed from a rigid inflatable boat (RIB) that was conducting tr ansects at low speed (Figure 3- 2).

Figure 3-1. Sea-Bird SBE-19 CTD Sensor with Integrated SCUFA® Fluorometer

Figure 3-2. Rigid Inflatable Boat

One rope was used to control the depth of the towed array, while a second rope was used
to control the distance of the to wed array from the discharge port. This second rope was tied to

3-33-4 the bow of the RIB and attached to the cruise vessel via a hull magnet affixed just above the
waterline at the location of disc harge port. Sensor depth was r ecorded electronically by the sampling array, while RIB location relative to the hull magnet was recorded manually by the sampling team onboard the RIB. The RIB sampli ng team also monitored sensor measurements, including Rhodamine WT dye concentrations, in real time using a laptop computer. The following measurements were collected by CTD + SCUFA® sampling array at 0.5 second intervals during the plume tran sects: dye concentration ( uncorrected; see Section 5.1); temperature; conductivity; depth (of the sensor array); turbidity; and salinity.

For most ships, a variety of transect types were conducted to provide detailed characterization of the discharge plumes (see Appendix A). Transect s can be described by visualizing polar axes on the water surface, w ith the location of the hull magnet corresponding to the origin, and the array location and movement indicated by a radius (distance from cruise vessel) and polar angle (estimat ed in degrees by the RIB sampli ng crew) (see Figure 3-3). For example, 90° indicates the array is located to the right of the discharge po rt at the ship’s hull, while 270° indicates the array is lo cated to the left of the discharg e port at the ship’s hull. Four different types of transects were performed to characterize the discharge plumes:

• Arc . Array was moved in an arc (e.g., 90° to 270°) at a fixed distance from the hull magnet. Arc transects at varying wa ter depths and distances from the hull magnet were the most common type of tr ansect performed, and were the primary means to locate and characterize discharge plumes.

• Inward or Outward Profile . Array was moved toward or from a fixed position on the hull (i.e., the hull magnet) at a c onstant angle (e.g., 225°). Inward and/or outward profiles were performed after th e location of the di scharge plume was determined using arc transects. Thes e profiles produced continuous dye dilution profiles determined by distance from the hull magnet.

• Stationary . Array was maintained at a fixed location (depth, distance, and angle from the ship) over a period of time. This profile produced a continuous dye dilution profile at a fixed array location as the plume moved past the array over time. This was the primary type of transect used for the Star Princess because the plume was visible on the surface of th e water (most likely because of the relatively shallow discharge port on the ve ssel; see Table 2-1), therefore an arc transect was unnecessary to find the plume. This type of profile also was used frequently for the Coral Princess , where ship discharge flow rates were highly
variable and/or intermittent.

• Depth Profile . Array was maintained at a fixe d distance and angle from the ship while the array was raised or lowered through the water colu mn. These profiles produced continuous dye dilution profiles by depth.0 5 10 15 20

- 2 0 - 1 5 - 1 0 - 5 0 5 1 0 1 5 2

meters to left (positive) and right (negative)of discharge port (located at zero)meters from discharge port 225°

270° 135°

90° 180°

0

Figure 3-3. Orientation of Arc Transects for Dye Measurements

3.5 Current and Weather Measurements

At least two current meters (S4 current meters, InterOcean Systems, Inc.) were deployed
off each cruise vessel to collect current measurements during the dilution studies (in some cases, three meters were used). The meters were depl oyed from the cruise vessels (to negate current meter motion relative to the vessels), approximate ly 15 meters away from the discharge port and approximately 3 meters out from the hull (to av oid interference from the vessel’s metallic hull with the magnetic sensor of the current meter). The current meters were deployed at depths of 1 and 3 meters (or at depths of 1, 3, and 5 meters if a third current meter was used). Current
measurements documented the ambient currents that affected the trajectory and dilution of the plume.

Weather conditions (e.g., air temperature, wi nd speed, and wind direc tion) were recorded by OSV Bold personnel during the dilution studies.

3-54-1 4. R ESULTS

4.1 Discharge Plumes

Uncorrected dye concentration data for al l transects are provided in Appendix B (see Section 5.1). In general, it appe ars that most near-field dilution occurs within 2.5 meters of the discharge port, with the plumes remaining relatively intact to distances of approximately 15 meters. The minimum dye dilution factors discussed in this report are the ratio of the initial dye concentration (i.e., dye concentr ation prior to discharge from the port) to the maximum dye concentration observed in the plume. The minimum dilution factor s observed during arc
transects conducted 15 meters fr om the discharge port ranged from approximately 40 to 90.

The following narratives provide a brief de scription of a complex dynamic phenomenon. The data collected in this study will be further analyzed by the ADEC to validate previous modeling studies on nearfield dilution of thes e treated sewage and graywater discharges.

Star Princess . This ship’s discharge port was the shallowest of all the sampled cruise vessels (see Table 2-1). The di scharge plume was the only one visible from the water surface; it moved along the hull at an angle between 255 and 270° from the discharge port location. Detected dye concentrations ranged up to appr oximately 57 ppb. It is unknown whether higher
concentrations would have been detected if th e CTD + SCUFA® array was able to measure dye concentrations near the surface of the water column (see section 5.1). Detected dye concentrations observed along the 270° transect were approximat ely similar at distances of 5 meters and 7.5 meters from the discharge port, and somewhat lower at a distance of 10 meters; however, the highest concentrati on of dye was observed on the 255° transect at a distance of 10 meters. EPA did not prepare a profile of arc transect results for the Star Princess because arc transects were not performed.

Coral Princess . Discharge from the Coral Princess was highly intermittent. During periods of no flow, the shipboard survey t eam suspended dye injection to minimize dye accumulation in the discharge piping, which coul d cause spikes and variability in discharge Rhodamine WT dye concentration. As a result, dye concentration data in Appendix B for the
Coral Princess represent intermittent wastewater discharge with discharge dye concentration variability that is not well characterized. Because of this variability and strong water currents, the discharge plume was difficult to detect. To ward the end of the sampling period, detected plume dye concentrations ranged up to 270 ppb and we re highly variable in concentration and in location (as measured both by dept h and degrees from the discharg e port). EPA did not prepare a profile of arc tran sect results for the Coral Princess due to the highly intermittent nature of the discharge.Ryndam . The discharge plume was most clearl y characterized moving at an angle of 135° from the discharge port. The discharge plume was also detected at angles of 180° and 90°, particularly toward the end of the sampling pe riod. Detected plume dye concentrations ranged from 5 ppb to approximately 20 ppb. During the ar c transects, the minimum dilution factor of approximately 34 was observed at 5 meters from the discharge port (note: this dilution factor is
based on an estimated initial dye concentration of 700 ppb). Maximum dye concentrations observed during arc transects, at various distances and depths ar e presented in Figure 4-1. For these transects, a minimum dilution factor of a pproximately 93 was observed 15 meters from the discharge port.

15 10 7.5 5 2.5

1.4 2.5 3.5 4.5

0.00 5.00 10.00 15.00 20.00 25.00Dye Concentration (ppb)

Distance from Discharge Port (meters)Depth (meters)

Figure 4-1. Profile of A rc Transect Results for Ryndam

4-2Celebrity Millennium . The discharge plume was most clearly characterized moving at angles ranging from 240° to 270° from the discharg e port. The discharge plume was observed at depths ranging from 5 to 7 meters. Detected plume dye concentrations ranged up to 47 ppb. During the arc transects, the minimum diluti on factor of approximately 11 was observed 2.5 meters from the discharge port. Maximum dye c oncentrations observed during arc transects, at various distances and depths are presented in Figure 4-2. For these transects, a minimum dilution factor of approximately 39 was obs erved 15 meters from the discharge port.

2.5

5

7.5

10

15 1.4 3.2 5.5 7.4

0 5 10 15 20 25 30 35 40 45 50Dye Concentration (ppb)

Distance from Discharge Port (meters)Depth (meters)

Figure 4-2. Profile of A rc Transect Results for Celebrity Millennium

4-3Norwegian Star . The discharge plume was most clea rly characterized moving at angles ranging from 250° to 270° from the discharge port . The discharge plume was observed at depths ranging from 3 to 5.5 meters. Detected plume dye concentrations ranged up to approximately 88 ppb. During the arc transects, the minimum diluti on factor of approximately 13 was observed 5 meters from the discharge port. Maximum dye c oncentrations observed during arc transects, at various distances and depths are presented in Figure 4-3. For these transects, a minimum dilution factor of approximately 43 was obs erved 15 meters from the discharge port.

2.5

5

7.5

10

15 1.4 3 5.5 7.5

0 5 10 15 20 25 30 35 40 45 50Dye Concentration (ppb)

Distance from Discharge Port (meters)Depth (meters)

Figure 4-3. Profile of A rc Transect Results for Norwegian Star

4-4Volendam . The discharge plume was most clear ly characterized moving at angles ranging from 125° to 225°. The discharge plume wa s generally observed at a depth of 5.3 meters with detected dye concentrations ranging up to approximately 21 ppb. During the arc transects, the minimum dilution factor of approximately 37 wa s observed 5 meters from the discharge port. Maximum dye concentrations observed during arc tr ansects, at various di stances and depths are presented in Figure 4-4. For these transects, a minimum dilution factor of approximately 45 was observed 15 meters from the discharge port.

15 10 7.5 5 2.5

1.4 2.8 5.3 7.3

0 5 10 15 20 25Dye Concentration (ppb)

Distance from Discharge Port (meters)Depth (meters)

Figure 4-4. Profile of A rc Transect Results for Volendam

4.2 Transect Water Quality Data

Data on water temperature, conductivity, de pth (of the sensor array), turbidity, and salinity from each transect are provided in Appe ndix B. Skagway Harbor salinity depth profiles (from the pre-dye transects for most ships) are provided in Appendix C. For all vessels, the halocline appeared to be d eeper than the discharge port (see Figures C-1 through C-4 in Appendix C).

4.3 Current Measurements and Weather Data

Current measurements collected during the cr uise ship plume dilution study are provided in Appendix D (see Figures D-1 through D-13 in Appendix D). For the polar plots, magnetic north corresponds to 0°. In Skagway, true north is 22.6° east of magnetic north. The heading of all the cruise vessels in this study was 40° east of true north. Therefor e, when analyzing the current data, the ship headings were 62.6° east of magnetic north.

4-54-6 The current meters were pre-programmed to begin data collection well before actual deployment from the cruise ships, and the meters continued to collect data until after their retrieval. Current data presented in this report include only the subset of data collected during the cruise ship plume dilution study (see Table 3-1).

National Oceanic and Atmospheric Administra tion Tide Tables for Skagway for July are provided in Appendix E. These tide tables are provided to suppl ement and inform the current

measurements.

Weather data (air temperature, wind spee d, and wind direction) recorded during the cruise ship plume dilution st udy are provided in Appendix H.5-1 5. D ATA Q UALITY

Quality assurance/quality control (QA/QC) procedures applicable for this program are
outlined in the Quality Assurance Project Plan for Support for OSV Bold Survey of Large Cruise Ship Wastewater Impacts in Alaskan Waters (QAPP) , which is reproduced in Appendix J. This section provides an assessment of the QAPP project data quality objectives specific to the cruise ship plume dilution study, which were established for the key measurements of the concentration of Rhodamine WT dye in the near-field plume a nd in the cruise ships di scharges. In addition, this section provides a brief quality assu rance assessment of non-key measurements.

Trial dilution studies were conducted on the Celebrity Millennium on July 7 and on the Norwegian Star on July 9 to refine the sample collecti on and analysis methodologies. Data from these trial studies are not presente d in this report. Sampling on the Celebrity Millennium and the Norwegian Star was repeated on July 15 and July 16, respectively.

5.1 Quality Assurance Assessment of Ke y Plume Dilution Study Measurements

For the cruise ship plume dilution study, the key measurements identified in the QAPP
are the concentration of Rhodamine WT dye in the near-fie ld plume and in the cruise vessel discharge (end-of-pipe). The data quality objectives for these meas urements are defined in terms of completeness, accuracy, precision, re presentativeness, and comparability.

Completeness (Near-Field Plume Dye Concentrations)

Dye concentration data in the near-field plume are complete for all vessels surveyed except the Star Princess . The discharge plume for the Star Princess was visible at the surface of Skagway Harbor. The CTD + SCUFA® array is designed to take measurements at approximately 1.5 meters of depth and deeper. As a result, data for the Star Princess do not characterize the entire plume, but only the portion of the plume deeper than approximately 1.5

meters.

Completeness (Cruise Ship Discharge Dye Concentrations)

Discharge dye concentrations were calcul ated by multiplying the measured discharge rates by the known feedstock dye concentr ations. On three cruise vessels ( Celebrity Millennium

, Norwegian Star , and Volendam ), a SCUFA® fluorescence sensor was installed on the discharge piping to verify dye concentrations. For the ot her three vessels, the SCUFA® sensor could not be used to verify dye concentrations due to damage sustained duri ng an unannounced emergency generator power drill on one of the ships. When fluorescence data could not be collected, the survey team verified dye discha rge by visual observation. Dye c oncentration was assumed to be
the calculated concentration.

Accuracy and Calibration

Dilution series performed for the three SC UFA® fluorometers prior to field testing showed excellent accuracy, with a highly linear response from approximately 5 ppb through 300 ppb. The dilution series and initial trial testing on Celebrity Millennium on July 7 revealed that the practical detection limit for the fluorom eters was the seawater background signal of5-2 approximately 1.6 ppb (contrary to the de tection limit of 0.04 ppb reported by the
manufacturer 2 ). A calibration curve for the range of 5 to 50 ppb was found to be linear (R 2 > 0.99). Actual dye concentrations are obtained using the following expression:

C = 0.768*C’ + 4

where C equals dye concentration and C’ is the uncorrected fluorometer response.

In consideration of the loss of two orders of magnitude of SCUFA® sensitivity, the survey team increased the targ et shipboard dye concentration from the planned 100 ppb to 700 ppb. Consequently, a second calibrati on curve was prepared for high dye concentrations. For the calibration range of 84 to 660 ppb, th e calibration curv e was linear (R 2 >0.99) and fit the following expression:

C = 1.02*C’ + 9

where C equals dye concentration and C’ is the uncorrected fluorometer response.

Precision and Representativeness

The QAPP specified collection of duplicate CTD+SCUFA® data using a pair of arrays towed side-by-side from the RIB. Field dupl icate sampling using two adjacent CTD+SCUFA® arrays was not performed. The secondary CT D+SCUFA® array was dismantled to provide a SCUFA® fluorometer to replace the damaged shipboard unit.

Comparability (Among Ship Discharge Tests)

The sample collection and analysis methodology was consistent for all cruise ship plume dilution studies. Dilution study transects were generally consis tent among ships, with some deviations necessary to account for ship-speci fic conditions and weathe r conditions during each

test.

Overall Data Quality Assessment

This data quality assessment indicates th at the key measurements collected during the cruise ship plume dilution study ar e of sufficient quality for use in analyzing near-field mixing dynamics of the effluent plumes from stati onary cruise ships in Skagway Harbor.

5.2 Quality Assurance Assessment of Non- Key Plume Dilution Study Measurements

Discharge Flow Measurements

Ship discharge flows were measured on all cruise vessels except the Norwegian Star . For
the Norwegian Star , discharge flows were measured only during the set-up period because the
meter malfunctioned at the start of the sampling period. Repeated attempts to reinstall the flow

2 Telephone contact with the manufacturer revealed that the reported detec tion limit can be achieved only under ideal, laboratory conditions.5-3 meter were unsuccessful. Therefore, Norwegian Star discharge dye concentration was measured using a SCUFA® sensor (as it could not be calculated using flow rates).

While discharge flow data were monitored by the shipboard survey team, they were not reliably logged electronically because of a smaller than expected data-logging buffer capacity.
For the Star Princess

, Coral Princess

, Ryndam, and Celebrity Millennium sampling events, electronic data logs are available for only th e last 7 to 15 minutes of testing. For the Norwegian
Star , electronic data logs are available for the last 2 hours of testing. For the Volendam

, electronic data logs are complete for the entire pe riod of testing. Electron ically logged discharge flow data were supplemented by field logs take n by the shipboard survey team (see Appendix F).

Two ships, Ryndam and Volendam , operated flow meters on their discharge. On both of these ships, ultrasonic flow me ter measurements closely matched measurements made by these ships’ built-in meters.

Current Measurements

Harbor current was measured during all sampli ng events for all six sh ips. For two of the six ships tested, current meters were deployed at 1, 3, and 5 meter depths. For the other four ships, current meters were deployed only at 1 and 3 meter depths due to the difficulty of deploying the meters. For one ship ( Norwegian Star ), current was not measured at the 1 meter depth due to water seepage into the connector cover on the meter. Current measurements collected are reasonable, based on their correlatio n to the location and dire ction of the detected plume.

Weather Data

Weather conditions (e.g., air temperature, wi nd speed, and wind direc tion) were recorded by the OSV Bold personnel during measurements of plume dilution, with the exception of
dilution measurements collected for the Coral Princess on July 11.