M a s s a c h u s e t t s W a t e r R e s o u r c e s A u t h o r i t y

questions and answers

about the new outfall

t h e S t a t e o f B o s t o n H a r b o r

1996

prepared under the direction of:Douglas B. MacDonald, Executive Director

John F. Fitzgerald, Director, Sewerage Division

board of directorsTrudy Coxe, Chair

John J. Carroll, Vice Chair

Lorraine M. Downey, Secretary

Norman P. Jacques

Joseph A. MacRitchie

Vincent G. Mannering

Donald A. Mitchell

Samuel G. Mygatt

Andrew Pappastergion

Robert Spinney

Marie T. Turner

Technical Report No. 1997-05

Second Printing

Massachusetts Water Resources Authority

N o v e m b e r 1 9 9 7

the state of boston harborquestions and answers about the new outfall

acknowledgements

prepared by:Andrea C. Rex

Michael S. Connor

edited by:Sally Rege Carroll

graphics by:Steve Hussey

Susan Curran Ford

Rita Berkeley

Jenny Siegel

Ilse Stryjewski

design and layout by:Rita Berkeley

Jenny Siegel

GIS data provided by:Massachusetts Department of Environmental Protection,

Massachusetts Division of Fisheries & Wildlife, MassGIS,

National Oceanic & Atmospheric Administration

acknowledgementsMany people contributed information and advice for this report. The authors wish to thank:

Don Anderson, Michael Bothner, Steve Cibik, Cathy Coniaris, Maury Hall, Doug Hersh,

Kenneth Keay, Josh Lieberman, Michael Mickelson, Michael Moore, Peggy Murray,

Carl Pawlowski, Michael P. Quinlin, Susan Redlich,Virginia Renick, Jack Schwartz, and Meg Tabacsko.

Special thanks to Wendy Smith Leo for her contribution.

Executive Summary

Part I:Boston Harbor Quality UpdateIntroduction

Boston Harbor Quality Update

Part II: The New Outfall: Frequently Asked QuestionsHow was the Massachusetts Bay site chosen?

How will the new outfall benefit water quality?

Will the discharge be very contaminated?

The seasonal cycle of the Bays

How healthy is the marine ecosystem of the Bays?

How will the discharge affect the health of the Bays?

What about the right whale?

Will we know if the outfall is causing a problem?

What will be done if a problem occurs?

Bay outfallwith secondarytreatment

(mg/L)

< 6

> 9

CapB

Bay

Boston

New Outfall

16.4 mi.9.5 mi.

36.6 mi.

Stellwa

Endnotes

References

List of web sites

contentstable of

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tablesTable 1: Comparison of primary and secondary treatment

Table 2: Toxic contaminants reduced by treatment

figuresFigure 1: Bacteria counts in Deer Island effluent

Figure 2: Solids discharged to Boston Harbor

Figure 3: PAHs in mussels near Deer Island decreased

Figure 4: Metals discharges to Boston Harbor declined

Figure 5: Industrial metals entering treatment plants

Figure 6: Water at Harbor beaches is cleaner

Figure 7: Healthier animal communities on the Harbor floor

Figure 8: Liver disease and contaminants in winter flounder

Figure 9: Location of outfalls in Harbor and Bay

Figure10: Schematic views of outfall and diffusers

Figure 11: Diluted effluent rises to surface in winter, and is trapped

beneath surface in summer

Figure 12: Dilution contours, Harbor and Bay outfalls

Figure 13: Secondary wastewater treatment schematic

Figure 14: The seasonal cycle of the Bays

list oflist of figures

1010

3333

3445678

91112

Figure 15: Resources and stressors in the Bays

Figure 16: Multiple sources of toxic contaminants

Figure 17: Distribution of silver in surface sediments

Figure 18: Winter flounder liver disease rates

Figure 19: Modeled surface chlorophyll a

Figure 20: Modeled dissolved oxygen in bottom water

Figure 21: Modeled particulate organic carbon deposition

Figure 22: Feeding northern right whale

Figure 23: MWRA monitors the Harbor and Bay at all scales

Figure 24: Monitoring locations in the Bays

Figure 25: Beneficial and nuisance algal blooms

Figure 26: Dissolved oxygen at the Bay outfall site

Figure 27: Sediment silver at the Bay outfall site

Figure 28: Contingency plan process flowchart

1415

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171719212222232325

he continuing improvementsin the waters of BostonHarbor have been describedin the State of BostonHarbor reports over the lastfew years. Elimination ofsludge discharges into theHarbor, prevention of float-

able pollution, and system improve-ments including the start-up of the newprimary treatment plant in 1995, havevisibly improved the Harbor’s environ-ment. Already, reductions in theamounts of pathogens, toxic metalsand petroleum products in the primaryeffluent have been accompanied byfewer swimmers’ advisories at Harborbeaches, evidence of healthier animalcommunities on the Harbor floor, and alower incidence of liver disease in theHarbor’s flounder.

In August 1997, the MassachusettsWater Resources Authority (MWRA)began the next phase of the BostonHarbor Project—the implementation ofsecondary treatment. Beginning in1998, a long outfall will discharge sec-ondary effluent into MassachusettsBay instead of into the shallowerwaters of the Harbor. This outfall relo-cation will allow the Harbor to continuerecovering from the poorly treatedsewage that it received for more thana century.

A draft of the new discharge permitfor the Deer Island Treatment Plant will

be issued soon. The development ofthe permit has revealed continuingquestions about the new outfall and itspotential impacts on Massachusettsand Cape Cod Bays. This reportaddresses frequently asked questionsabout this outfall, including the overar-ching concern: Could the Baysbecome degraded by sewage effluentas Boston Harbor once was? Theanswer is no, for these three reasons:

(1) Cleaner Effluent: Thesecondary effluent that will be dis-charged to the Bay will be muchcleaner than past discharges due to:

Source reduction: Fewer pollutantsare being allowed to enter the sewersystem, in part through stricter over-sight of industrial dischargers. Now,only a small portion of toxic metalsentering the treatment plants are fromindustrial sources.

Improved treatment: Secondarytreatment will remove even more cont-aminants before discharge and meetstringent state and federal waterquality standards. While primary treat-ment removes 50% to 60% of the totalsuspended solids in wastewater, sec-ondary treatment removes more than85% of these solids. Oxygen-depletingsubstances will also be more than85% removed, compared with 40%removed by primary treatment.

Toxic contaminants will be up to90% removed, compared to 50% by

primary treatment. Pathogens are sig-nificantly reduced by secondary treat-ment. With less solids in the waste-water, disinfection is more effective.

(2) Better Dilution: A four-year scientific and engineering study,regulatory review, and extensive publicparticipation determined that a dis-charge site 9.5 miles northeast of DeerIsland would be the best location forthe health of both the Harbor and theBay. The outfall, equipped with 440diffuser ports over the last 1.25 miles,will dilute the effluent in water 100 feetdeep in the Bay, compared to a depthof only 30 feet in the Harbor.

Computer modeling results indicatethat the effluent will have very limitedimpacts near the outfall in Massachu-setts Bay, and virtually no effect onCape Cod Bay. Surface chlorophyll a,a measure of algal blooms, willincrease only in the immediate outfallarea, and will be reduced significantlyin the Harbor.

(3) Constant Monitoringand Contingency Planning:MWRA’s National Pollutant DischargeElimination System (NPDES) permitfor the new treatment plant and outfall,which will be one of the most compre-hensive and protective permits everissued, will require that state andfederal water quality criteria not be vio-lated as a result of the discharge. In

addition, MWRA is required to conductan outfall monitoring program that islinked to its Contingency Plan, anaction plan that incorporates waterquality conditions that trigger MWRAaction. These trigger parameters arebased on permit limits, state waterquality standards, and expert scientificopinion.

Five years of baseline monitoringhave revealed much about the Baysystem’s natural variability, informationthat will help distinguish betweennatural and outfall-related phenomenaonce the outfall is on-line. Through vig-ilant monitoring, problems can bedetected and addressed.

The outfall’s impact has receivedextra scrutiny because of the importantrole that Cape Cod Bay plays in thelife of the endangered North Atlanticright whale. Although no effects areexpected, MWRA’s intensive moni-toring is designed to detect any outfall-related environmental changes thatmight affect the whales’ feedinggrounds.

While there are many sources ofpollutants to the Bays system, most ofthe Bays region supports a healthymarine ecosystem. MWRA's sec-ondary treatment and the better dilu-tion provided by the new outfall willcontribute to an overall improvement inthe health of the Harbor and Bays.

Tsummaryexecutive

boston harbor quality

Boston Harbor is an estuary that ispart of the Massachusetts Bayssystem. Conditions in the Harbor,including treatment plant discharges atthe existing, nearshore outfall loca-tions, measurably affect the Bay as aresult of strong tidal flushing. Improve-ments in the Harbor generally alsoimprove Massachusetts Bay.

Better wastewater management,including fewer untreated combinedsewer overflow discharges and reduc-tions in contaminants entering thesewage system, has substantiallylowered contamination in the Harbor.Figure 1 shows that MWRA's improve-ments to the reliability of disinfectionsince 1989 have greatly reduced thepathogens discharged to the Harbor.Figure 2 illustrates improvements inremoval of solids (and associated toxicpollutants) from the wastewater.Studies of contaminants in musselsplaced near Deer Island, for examplePAHs (Figure 3), confirm that environ-mental levels of toxic chemicals havealso decreased.

Dramatic reductions since 1989 intoxic metals contained in the effluentdischarged from MWRA’s treatmentplants are shown in Figure 4. Figure 5shows that industry's discharge of toxicmetals into the sewers now constitutesonly a small portion of the total metalsloadings. A challenge for the future willbe to decrease household and other

non-industrial contributions to toxicmetal loads in the wastewater receivedby MWRA treatment plants.

The benefits of better wastewatertreatment and management are mostapparent along the Harbor beaches,downtown along the walkways of theInner Harbor, and near the formersludge discharge site in PresidentRoads. Unsightly sewage-relatedfloating matter has been practicallyeliminated. Figure 6 shows that, for themost part, the number of swimmers’advisories (beach postings) due to cont-aminated water have declined since themid-to-late 1980s.

Bottom-dwelling animal communities,for example, the shrimp-like amphipodAmpelisca, have increased in abun-dance and diversity (Figure 7). Thehealth of winter flounder has improvedas shown by the decline of flounderliver disease since the mid-1980s(Figure 8a). Flounder caught in BostonHarbor are safe to eat, as illustrated inFigures 8b and 8c. PCB levels inflounder fillet are measured at about100 parts per billion—well below theFDA limit of 2,000 parts per billion. Like-wise, mercury levels in flounder fillet aremeasured at levels 10-fold lower thanthe FDA limit.

updatehe ongoing transformation of a once-degraded Boston Harbor to avalued regional resource is a story of environmental recovery. TheHarbor's progress over the past decade is due to ambitious anti-pollution projects, especially MWRA's new Deer Island sewagetreatment plant which serves 43 Boston area communities. Whensecondary sewage treatment is entirely on-line in 1999, sewage

treatment in the greater Boston area will finally be in compliance with thefederal standards prescribed in the 1972 Clean Water Act.

MWRA is now making progress toward two major milestones at the treat-ment plant: the three-part phase-in of secondary treatment from 1997 to1999, and completion of the 9.5-mile effluent outfall into MassachusettsBay. Secondary treatment will remove even more solids and toxic conta-minants from primary-treated wastewater. The new outfall will reach deepwater where over 400 diffuser ports will rapidly disperse treated effluent intothe marine environment.

Minimizing adverse effects of wastewater discharge on the marine envi-ronment includes three fundamental strategies:

1 aggressive source reduction: preventing pollutants from enteringthe waste stream and, in particular, enforcing strict limits on industry'sdischarge of toxic contaminants to the sewer system;

2 improved treatment: removing contamination from wastewater beforedischarge; and

3 effective dilution: mixing wastewater quickly with large volumes ofseawater to achieve very low concentrations of any remaining contami-nants in the marine environment.

Despite the benefits of improved treatment, the relocation of the outfallhas raised questions about the effects of discharging effluent into thewaters of Massachusetts Bay. This year’s State of Boston Harbor report isprincipally devoted to the major questions asked about the new outfall.

Tintroduction

PART I

2

Bacteria counts in Deer Island effluentnow rarely exceed permit limits

Sludge solids

Effluent suspended solids

Fiscal Year

150

120

90

60

30

1988 1989 1990 1991199219931994 19951996199719870

Tons Discharged per Day

1500

1200

900

600

300

1987 1991 1992 1993 1994 1995 19960

Parts per billion

200

0

Fiscal Year

Pounds per Day

400

600

800

1000

1200

199719961995199419931992199119901989

Copper

Zinc

Lead

Nickel

Chromium

Silver

COPPER LEAD CHROMIUM SILVER

CADMIUM MERCURY NICKEL ZINC

5.5 0.5 1

246 40 20

2

13

0.04

2.5

0.08

0.8

2

25

8.3

321

201-10,000 Fecal coliform/100 ml

>10,000 Fecal coliform/100 ml

Fiscal Year

200

150

100

50

1988 1989 1990 1991 1992 1993 1994 1995 1996 19970

Days per Year of High Counts

Figure 1. High bacteria counts in Deer Island effluent havedecreased dramatically since 1989. Graph shows number of days peryear that bacteria in effluent exceeded the permit limit of 200 coloniesper 100 ml. Extremely high (greater than 10,000) bacteria counts, oncecommon, have been eliminated. (MWRA monitoring data).

Figure 2. The amount of solids discharged to the Harbor from Deerand Nut Island treatment plants has decreased to about half that dis-charged in the late 1980’s, after the elimination of sludge discharges andimproved primary treatment. (MWRA monitoring data).

Figure 3. Low molecular weight polynuclear aromatic hydrocarbons,which are potentially cancer causing chemicals created by combustionof fossil fuels, are measured in mussels deployed and grown near DeerIsland. Levels of PAHs in mussels have remained relatively low since1993 (Mitchell et al. 1996, data for 1996 from Mitchell et al.,report inprep.).

Figure 4. Metals loadings to Boston Harbor from the Deer and NutIsland treatment plants have decreased dramatically since the 1980s.Decreases in FY 1992 reflect the elimination of sludge discharges intothe Harbor (MWRA monitoring data).

Figure 5. Industrial metals loadings in influent to the Deer and Nut Islandtreatment plants before treatment are only a small portion of the total. Thewedges show, for various metals, the pounds per day originating from indus-trial sources as compared to the total loading in influent (MWRA monitoringdata).

Solids discharged to Boston Harbor

PAHs in mussels near Deer Islanddecreased

Metals discharges to Boston Harborfrom MWRA treatment plants declined

Industrial metals are a small part of total metals entering treatment plants

(Pounds/day)

3

updateboston harbor quality

1989 -1990 Ampelisca Tubemats

Figure 7. Ampeliscatube mats have increas-

ingly colonized BostonHarbor since sludge dis-charges stopped, espe-cially in the area of theHarbor that was mostseverely affected: the

northern Harbor. Thesecrustaceans increase theamount of oxygen in the

sediments and are afavored flounder prey.

(Data through 1995 fromHilbig et al., 1996. 1996

data in prep, Hilbig et al.)

1995 Ampelisca Tubemats

1996 Ampelisca Tubemats

Ampelisca abditaThis tiny crustacean is pollu-tion-intolerant. Ampeliscalives in tubes that it buildsinto the sediment; thesetubes form thick mats thatprovide shelter for other smallanimals (illustration afterBousfield,1973).

50

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085-86 87-88 89-90 91-92 93-94

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085-86

Constitution Beach

Winthrop Beach

Short Beach

Carson Beach

Pleasure Bay

Malibu Beach

Tenean Beach

Perc

enta

ge o

f Bea

ch D

ays

Post

ed w

ith S

wim

mer

s' A

dvis

orie

s

87-88 89-90 91-92 93-94

Figure 6. Swimmers’ advi-sories have decreased sincethe late 1980s. Storm draincontamination and leakinglocal sewers remain a problemat Wollaston Beach. (Datafrom Metropolitan District Com-mission beach monitoringprogram.)

Water at Harbor beaches is cleaner

Healthier animal communities on the Harbor floor

4

Despite these documented improve-ments in Boston Harbor, its history ofproblems invites the question, “Could theBays become degraded by treatmentplant effluent from the new outfall?”Observers, experts, citizens, and marinescientists have generally concluded,"No." Three important reasons are: (1)the effluent to be discharged into the Baywill meet the secondary treatment stan-dard and thereby be much cleaner thanthe primary effluent and sludge that weredischarged into Boston Harbor until1991; (2) there is much greater dilutionat the discharge site in the Bay than inthe shallower waters of the Harbor; and(3) there will be constant monitoring ofMWRA's effluent and the water quality inthe Bays.

Throughout the report, we discussresults of scientific studies which haveincreased our understanding of the Baysecosystem and how pollution impactscan best be prevented. In addition, wepoint out areas of scientific uncertainty.Continual monitoring, linked to a flexible,evolving response plan, will help assurethat MWRA is accountable for examiningand re-examining areas of uncertainty.By obtaining and using new scientificinformation in its planning, MWRA and allothers interested in the health of theBays can work together to provide thebest protection for invaluable marineresources.

Questions about the new outfalldiscussed in this report are:

• How was the Massachusetts Bay site chosen?

• How will the new outfall benefit water quality?

• Will the discharge be very contaminated?

• How healthy is the marine ecosystem of the Bays?

• How will the discharge affect the health of the Bays?

• What about the right whale?• Will we know if the outfall is

causing a problem?• What will be done if a problem

occurs?

Figure 8a. The reduction in liver disease, including cancer, in winter flounder has followed thebanning of DDT and PCBs, and the decreasing discharge of PAHs from wastewater. (1984 flounderliver lesion data from Murchelano and Wolke 1985; 1987 data through 1995, from Mitchell et al. 1996,1996 from report in prep.)

The New Outfall: Frequently Asked Questions

PART II80

70

60

50

40

30

20

10

84

Liver Tumors

% o

f Dee

r Isla

nd Fl

ound

er w

ith D

iseas

e Early Liver Disease

87 88 89 90 91 92 93 94 95 960 00000

Less liver disease, lower contaminant levels in winter flounder

Figure 8b,c. PCBs and mercury in flounder caught off Deer Island have been well within guide-lines for human consumption since the mid 1980s, and have decreased since the late 1980s. (toxicchemistry data from National Status and Trends Program 1987; 1985 - 1991 data are from Schwartzet al. 1991 and 1993; 1992 - 1994 data from Hillman and Pevens 1995, 1996 data from Mitchell etal. report in prep.)

5

1985 1986 1987 1988

PCBs in winter flounder (fillet) caught near Deer Islandare well below the FDA limit of 2,000 parts per billion.Levels have greatly decreased since the mid-late 1980s.

1989

500

400

300

200

100

PCBs

in p

arts

per

billi

on

0

1987 1988

Mercury levels in winter flounder caught near Deer Island have been well below the FDA limit of 1,000 parts per billion. Levels have decreased since the late 1980s.

1989 1990 1992 1993 1994 1995 1996

1992 1993 1994 1995 1996

150

120

90

60

30 Mer

cury

par

ts p

er b

illion

0

... ...

......

The outfall siting process began in1986 with the appointment of the Facili-ties Planning Citizens Advisory Com-mittee (FPCAC), which included 27 par-ticipants representing agencies, envi-ronmental groups, community officials,and other interested individuals. TheFPCAC developed criteria used in thesiting process, and reviewed and com-mented extensively on the environ-mental impact reports.

At the outset of the siting process,the United States Environmental Pro-tection Agency (EPA) ruled acceptableonly those sites that (1) could providean initial dilution of 50 parts seawater toone part effluent; (2) were far enoughfrom shore so that particles could notbe transported directly to shore on thenext incoming tide; and (3) avoidedsensitive and unique resources.

The existing Deer Island and NutIsland discharge locations (Figure 9a)at the mouth of Boston Harbor did notmeet any of the above criteria—forexample, the dilution there is only 14parts seawater to one part effluent.Therefore, because of insufficientdepth and dilution, Boston Harbor wasnot chosen as a site for the new outfall.

Seven potential sites, from a locationin Broad Sound to a site 10 miles off-

shore, were evaluated in detail byMWRA and EPA independently. Sitesmore distant than 10 miles were elimi-nated from consideration because con-struction would not have been feasibleat a reasonable cost. Siting studieswere done in 1987 and 1988, includingengineering studies by four differentleading engineering firms as well as theMassachusetts Institute of Technologyand the Georgia Institute of Technology.Oceanographic work was done by Bat-telle Ocean Sciences, the New EnglandAquarium, MIT, and the US GeologicalSurvey. Biological, chemical, and phys-ical oceanographic information tosupport the siting analysis was col-lected in Broad Sound, Nantasket Bight,and western Massachusetts Bay.

Along with oceanographic measure-ments, a computer model of pollutant transport in Massachusetts and CapeCod Bays was used to predict likelyeffects of prospective outfall discharges:any discharge site had to show theability to attain compliance with stateand federal water quality criteria. Othercriteria to evaluate potential sites werebased on discussions with citizens andscientific advisory groups, and includedprotection of commercial on-the-wateractivities, maintenance and enhance-ment of aesthetics, and avoidance of

areas of important habitat.

The computer model predicted thatwater depth and current patterns wouldproduce the most effective dilution ofeffluent at three of the most distant can-didate sites. These predictions wereconfirmed by oceanographic fieldstudies.

After an extensive period of regulatoryand public review and comment, theFinal Supplemental EnvironmentalImpact Statement confirmed that the9.5-mile site (Figure 9b) was theoptimum location for the outfall becauseit is in an area of strong random off-shore currents, has a sufficient waterdepth, and would be feasible to con-struct. In 1988, the EPA published itsRecord of Decision on the outfall site,which also required MWRA to conductmonitoring of the effects of the oceandischarge on the Massachusetts Bayenvironment.

Massachusetts Bayhow was the

site chosen?fter a four-year long process including oceanographic and engineering studies, regulatoryreview, and extensive public participation, the 9.5-mile site for the outfall discharge was found tobe the best location for the health of nearshore and offshore waters.A

Cape CodBay

Massachusetts Bay

Provincetown

Boston

New Outfall

16.4 mi.9.5 mi.

36.6 mi.

Cape Ann

StellwagenBank

Figure 9b.Future outfall location in MassachusettsBay

6

Deer IslandOutfalls

OldNut IslandOutfalls (closed 7/98)

Boston Harbor

Figure 9a.Present outfall locations in BostonHarbor

Figure10a.The outfall tunnel is boredthrough bedrock, and the diffusersection of the outfall is located along thefinal 1.25 miles of the structure.

Sediment

Effluent

Bedrock

Figure 10c. The diffuser heads eachdisperse the effluent through eight ports.

Figure 10b. The 55 risers carry effluentfrom the deep rock outfall tunnel up to thediffuser heads at the seafloor.

0

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-350

-380

-100

100

50

-50

-100

-150

-200

-250

-280

0

Sea level

Depth below sea level (feet)

Depth below seafloor at diffuser end

������24' - 3"

Inside Diameter

Outfall Tunnel43,026' +

Seafloor

Slope: 0.05%6,600'+

Figure 10d. Cross-section diagram of outfall pipe

Diffuser head

Riser

Schematic views of outfall and diffusers

NOTE: Diagrams not drawn to scale

7

Figures 10a-d show the structure ofthe new outfall. The outfall will providea larger measure of environmental pro-tection than the existing outfalls. Cur-rently, wastewater is discharged withinBoston Harbor from two short (lessthan a mile long) outfalls at Deer Islandand three short outfalls at Nut Island.Because all wastewater treatment willbe consolidated on Deer island, it wasnecessary to build a larger outfall andto locate the discharge in deeper water.Since the continental shelf off the EastCoast has a very gentle slope, theoutfall had to be relatively long.

The new outfall is designed to maxi-mize mixing and dilution of effluent. Atthe present time, treated wastewatereffluents from the Deer Island and NutIsland treatment plants are dischargednear shore within Boston Harbor.Strong tidal currents eventually carrythe effluent into Massachusetts Bay, buteach incoming tide brings some of theeffluent back into the Harbor. Becausethe Harbor is shallow (on average only30 feet deep), the effluent plumesreceive little dilution and reach thesurface, where they are visible. Withonshore winds, the effluent can reachthe shoreline. By contrast, the new off-shore location is in an area where circu-lation is greater and more variable, pro-viding better mixing.

The new outfall (illustrated on theprevious page in Figure 10a-d) willcarry effluent 9.5 miles (15 kilometers)off shore to a location where Massa-chusetts Bay is 100 feet (30 meters)deep. The effluent will be dischargedthrough 55 diffuser heads each witheight outlets (ports), creating a diffuserthat altogether will be 1.25 miles (2000meters) long. The long diffuser areaand multiple ports will effectively dis-perse the effluent to maximize dilution.The initial dilution of the effluent at the

new location will be about 150 to 1,compared to the present dilution nearDeer Island of 14 to 1.

Because effluent is mostly freshwater, it is lighter than seawater. Buoy-ancy causes the effluent to rise towardthe ocean surface, rapidly mixing withthe surrounding water. This verticalmixing causes the density of theeffluent plume to increase, and themixed effluent becomes about as denseas seawater. This mixing happenswithin a few minutes, and within a dis-tance of tens of meters from the dif-fuser.

In the winter, the effluent plume, aftermixing, will reach the surface. In thesummer, effluent will be trapped belowthe surface because it quickly takes onthe same (denser) characteristics asthe bottom water (Figures 11a and 11b).

After initial mixing, whether the plumesurfaces or not, it will be mixed horizon-tally by currents at the new outfall site.These currents vary in direction, helpingto further disperse the effluent. Theoutfall is distant enough from shore sothat even shoreward currents will notcarry the effluent close to beaches orshellfish beds.

apid mixing with a large volume of seawater willquickly dilute the constituents of the effluent to background levels.R Figure 11a. What ultimately

happens to the effluent plume dependsupon seasonal effects on the density ofocean water in Massachusetts Bay. Sea-water density is controlled by tempera-ture and salinity. Warmer temperaturesand lower salinity make seawater lighter,while cooler temperatures and highersalinity make seawater heavier. In thewinter, the waters of the Bay are aboutthe same density top to bottom and arewell mixed. When the seawater has arelatively uniform density top to bottom,the effluent plume will rise to the surfaceas it mixes.

Diluted effluent risesto surface in winter

Figure 11b. In the summer, thesurface water is warmed and becomesincreasingly lighter, setting up a layeringeffect. The level where the densitychange is most abrupt is called the pycn-ocline.

Effluent becomes increasingly denseas it mixes with seawater, and will rise uponly to the depth where it is no longerlighter than the surrounding water—atthe pycnocline. Thus the effluent plumewill be trapped below the pycnocline. Atthe outfall site, this is about 50 feet (15meters) below the surface.

8

how will the newoutfall benefit water quality?

Diluted effluenttrapped beneathsurface in summer

Diffuser head

Sea Floor

Sea Surface

30 meters

Buoyant freshwater effluentrises and mixes rapidly

Effluent mixed with seawater rises to the surf

Seawater is cold, dense,and well-mixedfrom surface tobottom.

Diffuser head

Sea Floor

Sea Surfac

Surface layer: seawater is well mixed and less dens

Pycnocline layer: seawater density increaseswith d

Bottom layer: seawater well mixed and denser

Through mixing, effluent reaches same density as surrounding water and stops rising

5 meters

10 meters

Buoyant freshwater effluentrises and mixes rapidly

15 meters

DILUTION AREA

< 200

200 - 400

400 - 600

600 - 800

800 -1000

Average ModeledDilution of Sewage Effluent

(Square miles)

77

56

59

77

116

DILUTION AREA

< 200

200 - 400

400 - 600

600 - 800

800 - 1000

Average ModeledDilution of Sewage Effluent

(Square miles)

3

30

151

48

54

Figure 12a. Figure 12b.Moving the outfall offshore greatly reduces the area most affected by effluent. These two figures show the results of computer model predictions of effluent dilution during winter conditions at the present and future outfalllocations. At present (12a), 77 square miles all of Boston Harbor and the South Shore to Cohasset Harbor, now have a dilution factor of less than 200-fold. At the future outfall location (12b), only 3 square miles, immedi-ately above the diffusers will have a dilution of less than 200-fold. The dilution model assumes concentrations in effluent are the same for both Harbor and Bay outfalls: this is true for nutrients. The illustration does nottake into account the effect of improved treatment in lowering the concentrations of contaminants in effluent. Model predictions based on winds and currents, winter 1990-1991. (Model created by R. Signell and H. L.Jenter of the U. S. Geological Survey and A. Blumberg of HydroQual, Inc.)

Dilution contours, Harbor outfall location Dilution contours, new Bay outfall location

9

Treatment is a critical step in mini-mizing adverse effects of sewage dis-charges. The centerpiece of the BostonHarbor Project is the state-of-the-artprimary and secondary treatment plantnearing completion on Deer Island.This massive, multibillion dollar projectwas built to comply with strict environ-mental regulations in order to protecthuman health, the health of the Harbor,and the ecology of the Bays system.

The secondary-treated wastewater tobe discharged into Massachusetts Bayis very different from the inadequatelytreated primary effluent and sludge thatwere discharged into Boston Harbor fordecades. As shown in Table 1, whileprimary treatment removes 50 to 60percent of the total suspended solids inwastewater, secondary treatmentincreases the removal ofsolids to 85 percent ormore.

Table 2 shows thelevels of toxic pollu-tants in primary andsecondary treatedeffluent, and the pre-dicted concentrationsin the area around thenew outfall after dilutioncompared to water qualitystandards.

After secondary treatment (Figure

13), the concentration of toxic pollu-tants in the effluent is very low–mea-sured in parts per billion or parts pertrillion. Levels of many of these pollu-tants in the secondary effluent arealready low enough to meet regulatorystandards for receiving water. In fact,after dilution at the new outfall, mostcontaminants are 10 to 1000 timeslower than water quality standardsallow.

Nutrients are the only components ofsewage entering the treatment plantthat are not significantly reduced bysecondary treatment. Therefore,MWRA carefully monitors the potentialeffect of nutrient issues on the Bayssystem, and nutrients have receivedparticularly intensive scrutiny by regula-tory agencies.

Table 2. Toxic contaminants reduced by treatment and dilutionHelpful Microbes

Tiny microbes includingbacteria, ciliates, androtifers, as seen herethrough a microscope atabout 500-fold magnifica-tion, are the key to sec-

ondary treatment. Thesehelpful micro-organisms feed

vigorously on the wastewaterduring treatment, breaking down

and removing contaminants.

be very contaminated?dischargewill the

he secondary effluent discharge will meet stringent state and federal standardsto ensure that it will not pose a threat to either human health or the health of theenvironment.T

Pollutant

Total suspended solids (TSS)

Biochemical oxygen demand (BOD)

Toxic contaminants

Nutrients

Pathogens

Primary removal

50-60%

25-40%

0-50%

5%

0-50%*

Secondary removal

85+%

85+%

50-90%

10-15%

80-99+%*

Table 1. Comparison of primary and secondary removal of pollutants

*These numbers indicate removal before disinfection. Disinfection further reduces pathogens to safe levels.

Parts per billion (micrograms/liter)

Copper DDTsLeadMercuryTOTALPAH

Primary effluent1

Secondary effluent1,2

Concentration afterdilution3

Receiving waterquality standards4,5,6

103

21.6

0.27

2.9

29.2

3.3

0.04

8.5

0.3

0.1

0.0013

0.025

31

3

0.008

2.02

57

12

0.033

0.045

54,932

3,250

8.93

42,000

TOTALPCBs7

Parts per trillion(nanograms/liter)

Tables 1 and 2. Secondary treatment at the Deer Island treatment plant, combinedwith dilution at the new outfall, will ensure that levels of toxic contaminants in the receiving watersare well within water quality standards. The table shows selected toxic constituents of wastewaterthat are regulated by EPA. For most constituents, the final concentration in the receiving water willbe far lower than EPA criteria (for details see end note, p.26).

10

Nutrients, especially nitrogen

and phosphorous, are familiar as the active ingredi-

ents in lawn and agricultural fertilizers. Nutrients

are also essential for the growth of plants (sea-

grasses, seaweed, and microscopic floating algae

called phytoplankton) in the ocean. In the marine

environment, excessive amounts of nutrients, espe-

cially nitrogen, stimulate the growth of phytoplank-

ton and seaweeds and can cause nuisance algal

blooms like brown or red tides (eutrophication). The

eventual decaying of these plants can deplete dis-

solved oxygen levels in the water and sediment.

Nutrients from the present outfalls exit theHarbor to the Bay in effluent plumes at the sur-face of the water, where sunlight and nutrientsinduce abundant phytoplankton growth. Onemajor benefit of the new outfall is that dilutedeffluent will be discharged at the bottom ofMassachusetts Bay, 110 feet below the water'ssurface. During the summer when there is themost light, the discharge will be trapped bystratification about 50 feet below the surface.Most phytoplankton growth is at the surface,where there is a lot of light. Nutrients from thedischarge at the sea floor will generally notreach the surface during the summer, whenthere is the most potential for excess growth.Therefore, the outfall is not likely to contributeto eutrophication in the Bay.

Secondary Reactors

Atmosphere

Pure

Oxy

gen

Contam

inted air from reactors Odor Removing

Air Scrubbers

Primary Effluent toSecondary Treatment

Cryogenic Oxygen Facility

Effluent to Outfall

Secondary Effluent

Secondary Influent

Return Activated Sludge

Sludge

Waste Sludgeto Centrifuge,Digesters, &Pelletizing Facility

Disinfection Chambers

Secondary Clarifiers

Secondary wastewater treatment schematic

Figure 13. Secondary wastewater treatment follows pri-mary treatment at Deer Island. Primary treatment removes solidsby simple physical processes: in settling tanks (clarifiers), heavysolids (sludge) sink to the bottom and lighter solids (scum) float tothe surface. These solids are removed; the remaining liquid is pri-mary effluent, which is then undergoes secondary treatment.Within the secondary reactors, the primary effluent is mixed withpure oxygen. The oxygen and mixing stimulate the rapid growthof beneficial microbes (bacteria, protozoans, and other tinyorganisms) in the wastewater, which consume more solids and

break down contaminants. After about two hours, more sludgeand scum are separated out in the secondary clarifiers. A por-tion of the secondary sludge, rich in beneficial microbes (acti-vated), is returned to the reactors, where it is used to treat moreprimary effluent. Waste sludge and scum are sent to DeerIsland’s egg-shaped digesters, to be further broken down bymicrobes and eventually converted to fertilizer pellets. The clari-fied secondary effluent is disinfected and discharged to theocean through Deer Island’s outfalls (Figure after D. Duest,MWRA)

nutrients

11

undamental to all the processes in the Bays is the annual sea-sonal cycle. In order to be able to recognize the effect of efflu-ent discharge on the environment, it is important to first under-stand the changes that happen naturally. Over the past five

years, MWRA’s baseline monitoring program and extensive studiesby the US Geological Survey and the Massachusetts Bays Programhave provided a good understanding of the Bays' seasonal cycle.

In November through April, winds and cooling mix the waters of theBays. Nutrients are plentiful, but in December and January the pene-tration of light into the water is rarely enough to support the growth ofphytoplankton (microscopic floating algae at the base of the foodweb). As the days lengthen in early spring, increases in light and innutrient levels trigger the rapid growth of phytoplankton.

The spring bloom of phytoplankton starts in the shallower waters ofCape Cod Bay, providing food for zooplankton (tiny animals, includingjuvenile forms of animals like fish and jellyfish, and abundant tinycrustaceans called copepods) carried into the Bays by strong currentsfrom the Gulf of Maine. In turn, the fast-multiplying zooplankton pro-vide food for many marine species including the northern right whale.A single right whale feeding in Cape Cod Bay can consume aboutone ton of these plankton daily.

Later in the spring, the surface waters of the Bays warm and strat-ify. The phytoplankton grow abundantly at the surface, where theyreceive ample light. Because vertical mixing is prevented by stratifica-tion, the nutrients at the surface do not get replenished from the bot-tom waters. The phytoplankton use up the nutrients in the surfacewater and die, eventually sinking to the bottom and providing food tothe bottom-dwelling animal communities which show a growth spurtin mid-summer.

In the water column, bacteria use up dissolved oxygen throughtheir respiration as they consume the dead plankton; the lowest dis-solved oxygen levels in the Bays occur from August to October. In thefall, cooling of surface waters and strong winds allow mixing through-out the water column, bringing fresh nutrients to the surface, stimulat-ing a new growth of phytoplankton—the fall bloom. By mid-winter,light levels have declined, ending the fall bloom. The plankton die anddecay, releasing nutrients. Nutrient levels increase throughout thewater column, preparing the Bays for the next spring bloom.

Fthe Baysthe seasonal cycle of

12

January February March

S p r i n g B l o o m

April

11

9

7

35 40 45 50 55 60 65

Legend

Color indicates approximate watertemperature (F)

Waters are cold andwell mixed and rich in nutrients

Longer days spurphytoplankton growth.

Right whales feed onabundant zooplanktonin Cape Cod Bay andStellwagen Bank.

Dead plankton ce

Little daylight

in winter

Figure 14.

13

Dissolved Oxygen Concentration (mg/L)

S t r a t i f i e d P e r i o d

May June July August September October November December

11

9

7F a l l B l o o m

Phytoplankton use

up nutrients in surface

waters, plankton growth slows.

Stratification: minimal mixing between surface and bottom.

Surface watersbegin to cooland mix downward.

Fall and winter windsaid in mixing.

Mixing causes nutrients to increasein surface waters: fall bloom.

cells and fecal matter from zooplankton drift down through the water column. As this material decays, nutrients in the water are replenished.

Warming decreases surface water density

marine ecosystemhow healthy is the

he Bays system supports a rich and diverse ecosystem of normal plant and animal communities, but signs of stress are evident.Stress results from multiple causes, including overfishing and contamination. The highest levels of contamination are nearshore—sources include rivers, the atmosphere, sewer overflows, treatment plants, and past use of disposal areas.T

of the Bays?

An overview of the Bays systemAt the southern end of the Gulf of

Maine, the Massachusetts/Cape CodBay system extends from the NewHampshire border to the tip of CapeCod, encompassing about 1650 squaremiles.

A strong southward coastal current anda large flow of water from the MerrimackRiver produce an average flow souththrough the Bays, exiting to the openAtlantic (Figure 15). Strong tide and windeffects produce circulation patterns thatare highly variable from day to day.

Rich resources and multiplestressors

The beaches, wetlands, rocky shores,and deep offshore waters of the Baysprovide important habitat for many plantand animal communities including com-mercially important species of fish andshellfish, and rare or endangered ani-mals and birds.

There are a variety of environmentalstressors in the Bays system: historicalwhale hunting and ongoing commercialfishing; disappearance of habitat such assalt marshes; dams that hinder fishmigration and spawning; commercialshipping and boating activities; and pollu-tion.

Many sources of pollution, pastand present

Bacterial contamination of beachesand shellfish beds is a concern alongmost of the Bays’ coastline. The chiefsources of this contamination are sewerpipe overflows, stormwater runoff, andleaks from septic systems. Treatmentplants are a relatively minor source ofcontamination.

Levels of toxic contaminants in thewater are highest near the coast and,except for a few pollutants like polychlori-nated biphenyls (PCBs), generally meetwater quality standards throughout theBays. However, the sediments nearurban shorelines like Boston Harbor,Salem Sound, and Broad Sound havesignificant levels of contamination.

In sediments, as in the water column,contaminant levels decrease with dis-tance from shore except at former wastedisposal sites in Massachusetts Bay.Contamination in offshore sediments isnot high enough to cause detrimentalecological effects, according to NationalOceanic and Atmospheric Administrationstandards. In fact, monitoring has shownthat the bottom-dwelling animal commu-nities are typical of the Gulf of Maineecosystem.

Toxic organic compounds and metalshave many sources. Three examplesillustrating this are chlorinated pesticides(especially DDT and its breakdown prod-ucts), PCBs, and mercury. DDT wasbanned in 1972 and PCBs were phased

Cape Cod BayMarine Sanctuary

Stellwagen BankNational Marine

Sanctuary

Stellwagen Bank

Barrier beaches

Former Mass Bay Disposal Site, or Foul Area (FA)

Shipping Lane

Industrial discharges

Legend

Average ocean current direction

State OceanSanctuary

Federal MarineSanctuary

State Area of CriticalEnvironmental Concern

Former Industrial Waste Site (IWS)

Present Mass. Bay Disposal Site (MBDS)

FA

IWS

MBDS

Cape Cod BayArea of Critical

Environmental Concern

(Right Whale Sanctuary)

Cape Cod BayOcean Sanctuary

North EssexOcean Sanctuary

South EssexOcean Sanctuary

New MWRA outfall site

Sewage treatment plantoutfalls

Figure 15.Resources and stres-sors in Massachusettsand Cape Cod Bays

14

out of production beginning in 1971.These contaminants can bioaccumulatein marine mammals and fish.

Figure 16 shows that the presentinputs to Massachusetts Bay from allsources combined of PCBs and chlori-nated pesticides are a small fraction ofthe amounts that have accumulatedfrom past inputs, when the chemicalswere being used in large amounts. Sec-ondary treatment will greatly reduceMWRA’s contribution of PCBs to Mass-achusetts Bay. The amounts of PCBs

and chlorinated pesticidesentering the Bays will continueto decrease in the future, andare slowly degrading in the environment.

Historical contamination signalsMWRA’s monitoring program has

revealed that past sewage dischargesinto Boston Harbor have contributedcontaminants to broad areas of CapeCod Bay as a result of tidal flushing.Past inputs of sewage and sludge inBoston Harbor contained silver, whichwas historically discharged in largeamounts by the photographic industry.A gradient of silver extends from the

Harbor to Cape Cod Bay (Figure 17),with higher concentrations in parts ofCape Cod Bay than in other offshorewaters. Because the Harbor apparentlywas the source, these silver concentra-tions correspond quite well to the mod-eled dilution of the effluent dispersedinto Massachusetts Bay from the exist-ing Harbor outfalls (Figure 12a).

Despite the pattern of silver (andother sewage tracers not shown), thecontaminants are not causing signifi-cant impacts on the health of marine lifein Cape Cod Bay. Bottom-dwelling ani-mal communities in the Bay are typicalfor the Gulf of Maine as a whole. Datagathered on winter flounder (Figure 18)

show that contaminant-related liver dis-ease is at very low levels in Cape CodBay compared to the area close toBoston Harbor.

Future decreases in contamina-tion

As MWRA’s contribution of toxic pol-lutants continues to decrease due tosource reduction and treatmentimprovements, the existing gradient ofpollutants in the Bay should graduallylessen. In addition, moving the effluentdischarge to the new outfall site (seepage 9) will reduce the concentration ofdissolved contaminants reaching CapeCod Bay from Boston.

Eastern Cape Cod Bay

Future Outfall site

Nantasket Beach

Broad Sound

Deer Island Flats

44%

22%

43%

14%

2%

Winter flounder liver disease rates

Figure 17. Sediment silver concentrations (measuredas parts per million of the mud fraction of sediment)decrease with distance from the coast. Cape Cod Bay hassomewhat higher silver concentrations than more northernlocations; this may reflect sediment resuspension and trans-port by currents to Cape Cod Bay (data from Bothner et al.1993).

0.18

0.150.231.181.82

0.42

5.75.5

8.9

0.27

0.32

0.51

0.69

2.7

Figure 18. Flounder liver disease is high in Boston Harbor and BroadSound, and low in Cape Cod Bay. The percentage of flounder showing earlyliver disease decreases with distance from Boston Harbor—flounder at thenew outfall site may be affected by toxic pollutants from the coastal sourcesor from old waste disposal sites. Improved treatment, continued sourcereduction, and improved dilution and dispersion at the new location will min-imize flounders’ exposure to the contaminants (PAHs,pesticides, and PCBs)thought to cause this disease (data from Mitchell et al. 1996).

Distribution of silver in surfacesediments

Figure 16. Annual inputs (loadings) of chlorinatedpesticides and PCBs to Massachusetts Bay are small com-pared to existing accumulations from past sources. Thesource of mercury is primarily atmospheric. Secondary treat-ment reduces MWRA’s contributions. The pie chart areasreflect the relative amounts of present vs. future loads.(Annual loading data from Mitchell et al. 1997, Massachu-setts Bay estimates of existing inventory from data by Shea,1993, 1996 in prep.; Bothner et al. 1993. Estimates based onmodel in Shea 1995).

Multiple sources of toxic contaminantsto the Bays

15

Chlorinated Pesticides Total = 20.7 kg/year

PCBs Total= 51 kg/year

Chlorinated PesticidesTotal = 8.8 kg/year

MercuryTotal = 358 kg/year

MercuryTotal = 332 kg/year

PCBs Total = 27 kg/year

Present Annual Loading: MWRA Primary Treatment

Future Annual Loading; MWRA Secondary Treatment

Chlorinated Pesticides (kg)

PCBs (kg) Mercury (kg)

Water

Sediment

39

430-1520

47

510-1800

300

40,000-80,000

Estimated existing inventories in Massachusetts Bay

Other sources

Atmosphere Rivers

Other Treatment Plants

MWRA

Legend

sing computer modeling, MWRA has predicted that increased pollutant removals by sec-ondary treatment, combined with improved dilution of effluent provided by the new out-fall, will improve the health of Boston Harbor and Massachusetts and Cape Cod Bays.U

Computer model Scientists assisting MWRA have

developed a detailed computer modelto predict impacts on Boston Harborand the Massachusetts and Cape CodBays from discharges of secondary-treated effluent at the new 9.5-mileoutfall location. This forecast is con-trasted with modeled impacts from thedischarges of primary effluent at theoutfall location near Deer Island withinBoston Harbor. The model is a time-variable, three-dimensional, hydrody-namic and water quality model calledthe Bays Eutrophication Model. It wasdeveloped by the U. S. GeologicalSurvey and Hydroqual, Inc., the com-pany that also developed water qualitymodels for the Chesapeake Bay andLong Island Sound.

Verifying the modelIn the course of developing and test-

ing the model, modeling results werecompared to actual environmentalobservations in the Massachusetts Baysystem made in 1989-1992. Themodel results agreed quite well withobserved data, and reproduced themajor processes affecting the Bayssystem: the annual cycle of surfacewater heating and stratification; thespring freshet associated with the Mer-rimack River and other northern riversdischarging to the Gulf of Maine; the

annual cycle of phytoplankton growth;the annual cycle of nutrients in the sur-face and bottom waters; and the effectof stratification on the minimum dis-solved oxygen concentrationsobserved in October.

After the usefulness of the computermodel was established by these tests,scientists used the model to predict thelikely impacts of discharging secondaryeffluent through the new outfall intoMassachusetts Bay. Figures 19-21show the model predictions for threemajor components of concern: surfacechlorophyll a, bottom dissolved oxy-gen, and particulate organic carbonflux.

Chlorophyll aBecause primary and sec-

ondary treatment do little toremove nutrients fromsewage effluent, one of themajor questions regardingrelocation of the effluent dis-charge to the 9.5-mile siteoffshore is what effect nutri-ents would have on phyto-plankton growth: wouldadding nutrients offshorepromote blooms of phyto-plankton? One importantmeasure of the status ofeutrophication in the Bayssystem is the concentration

of chlorophyll a, a major algal pigmentthat is a good measure of phytoplank-ton abundance.

Figures 19a and 19b show concen-trations of chlorophyll a at the surfacefor Boston Harbor and MassachusettsBay predicted by the Bays Eutrophi-cation Model. The figures show a five-day average in August, when the Baysare stratified. There is a largedecrease in surface chlorophyll a lev-els in Boston Harbor and no increasein Massachusetts Bay after the 9.5-mile outfall and secondary treatmentare on-line. This is largely because ofimproved dilution, and because at thenew deeper location, discharged nutri-ents will mostly be below the summerpycnocline in the Bay. Nutrients willnot be available to phytoplankton at

the surface, where there is enoughlight to support vigorous growth.

Dissolved oxygen in bottomwater

Animals and plants living in themarine environment need adequatedissolved oxygen (DO) in the water forrespiration. If DO levels fall too low,fish and other animals may die. Bot-tom waters, because they are not incontact with the atmosphere, are mostlikely to experience low DO. Factorsthat decrease the levels of DO in thewater are: high water temperature—oxygen is less soluble at warmer tem-peratures, and respiration rates of alllife increase; too much oxygen-demanding organic matter in the sedi-ment; and stratification of the water

(ug/L)

Bay outfallwith secondarytreatment

< 1

5(ug/L)

Harbor outfallwith primarytreatment

10

< 1

16

Figure 19. Modeled surface chlorophyll a, August

a b

how will the discharge affect the healthof the Bays?

column, which prevents more highlyoxygenated surface waters fromreaching the bottom. Concerns aboutthe outfall related to dissolved oxygenare whether inputs of materials thatuse up oxygen (measured as bio-chemical oxygen demand, or BOD)and nutrients might cause bottom DOto violate the water quality standard.Monitoring has shown that bottomwater DO has occasionally fallenbelow the standard at the new outfallsite. The state standard for DO is 6mg/l in Massachusetts Bay, and 5 mg/lin most of Boston Harbor.

Bottom DO levels are generally low-est in October because the water col-umn has been stratified since April(see page 12). The model shows thatwith the Harbor discharge and primarytreatment (Figure 20a), the lowest DOis in the Inner Harbor, and DO is alsodepressed near the future outfall area.This offshore DO depression is partlynatural, and partly reflects the present

export of nutrients and BOD fromBoston Harbor. Figure 20b shows thatsecondary treatment and the long out-fall result in improved bottom DO, bothin the Harbor and near the outfall.Most of this improvement is explainedby increased removal of BOD throughsecondary treatment.

Particulate organic carbon flux

The animal communityliving on the ocean floorrelies for food on organicmatter deposited to thesediment through the over-lying water column—theparticulate organic carbon(POC) flux. However, depo-sition of too much organicmatter in the sediments candeplete sediment DO.Excess food as POC willdestabilize the normal com-munity structure, leading to

decreased diversity, as has happenedin Boston Harbor. POC can be con-tributed directly by an effluent dis-charge, or indirectly by increased phy-toplankton and zooplanktonabundance, some of which ultimatelydeposit in the sediments. A concernwith the 9.5-mile outfall location hasbeen the potential effect of adding

POC to the sediments near the newoutfall.

The model shows a high depositionrate in Boston Harbor with the presentoutfall and primary treatment (Figure21a). With the new outfall and sec-ondary treatment, POC flux is dramati-cally reduced in both the Harbor andthe Bay (Figure 21b).

(mg/L)

> 9

< 6

Bay outfallwith secondarytreatment

(mg/L)

Harbor outfallwith primarytreatment

< 6

> 9

(mg C/m2-d)

Harbor outfallwith primarytreatment

1000

< 125

(mg C/m2-d)

1000

< 125

Bay outfallwith secondarytreatment

17

Figure 20. Modeled dissolved oxygen in bottom water, October

a b

Figure 21. Modeled deposition of particulate organic carbon

a b

right whale?what about the

The northern right whale (Eubalaenaglacialis) is the world’s most endan-gered large whale. From an originalpopulation size of at least 10,000 ani-mals, extensive hunting for more than800 years drove the species to near-extinction. Only about 300 individualsremain in the North Atlantic; fewer inthe North Pacific. Despite an interna-tional ban on hunting right whales since1949, the population is increasing at avery slow rate, in contrast to other pro-tected whales which have recoveredmore quickly.

The explanation of this slow recoveryis not known. Natural causes suchas competition with other species, orgenetic factors like inbreeding, orbehavioral factors may be important.Human-induced mortality includes colli-sions with ships and entanglement withfishing gear. Finally, habitat degradationhas been identified as a potentiallyimportant cause of the whale popula-tion’s low rate of increase. Reduction infood availability, physical interferencewith whales through shipping, miningand dredging activities, and pollutionimpacts are factors that could degradewhale habitat.

Cape Cod Bay and Stellwagen Bankare important late winter/spring feedingareas for these migratory animals, andhave been identified by the NationalMarine Fisheries Service (NMFS) ascritical habitat to be protected. Therefore

potential pollution sources like theMWRA outfall must be reviewed underthe Endangered Species Act, althoughthe long outfall discharge isdistant–more than 16 miles–from identi-fied right whale habitat.

In 1993, EPA conducted a compre-hensive Biological Assessment on thepotential impact of the MWRA outfall onendangered species and NMFS issueda Biological Opinion. The conclusionwas that the outfall was not likely tojeopardize the species. Nevertheless,the critical status of the right whalerequires special and continued consider-ation. Issues that have received ongoingscrutiny include the potential for impactsfrom pathogens, toxic chemicals, andnutrients, as described below.

Will the whales be threatenedby infectious bacteria, virusesor protozoans in the effluent?

Secondary treatment is highly effec-tive at removing pathogens from thewastewater. Secondary-treated effluentis also disinfected more effectively thanprimary effluent. Improved removal com-bined with higher dilution will signifi-cantly decrease the levels of pathogensin both the Harbor and the Bays. Themicrobiological water quality will meethuman swimming standards and themuch more stringent shellfishing stan-dards. These standards should be suffi-

ciently protective of the whales as well.

What about toxic and bioaccu-mulation effects of metals andPCBs?

Levels of these contaminants in thedischarge will be so low (page 10) thatshort-term, acute toxic effects are not aconcern. The focus is on average levelsof contamination Bay-wide and theeffects of long-term chronic exposure,such as bioaccumulation, and thepotential for sublethal effects likedecreased fertility.Measurements of organochlorine com-pounds, like PCBs, in right whales indi-cate relatively low tissue levels com-pared to other marine mammals.Although exposure to toxic chemicalsmay possibly be a factor in right whalereproductive failure, moving the outfalllocation from within the Harbor to the9.5-mile location offshore will notincrease the risk to whales because theinputs of these contaminants to theBays system will not be increased.Rather, secondary treatment will sub-stantially decrease any toxic chemicalsMWRA contributes to the Bays system.

Will increased nutrients causedecreased food availability?

In order to better understand nutrientissues, it helps to know somethingabout the feeding biology of the north-

ern right whale (see illustration, Figure22). Right whales are baleen whales;they feed by swimming open-mouthedthrough patches of zooplankton, strain-ing millions (about one ton a day) of tinycrustaceans, called copepods, from thewater. In the spring, right whales feed inCape Cod Bay and Stellwagen Bank,where there are intense blooms of largeand nutritious copepods like Calanusfinmarchicus. The whales feed in denseCalanus patches, created by wind andcurrent patterns as well as copepodswimming behavior.

Offshore Calanus zooplankton com-munities differ from their nearshorecounterparts. Nearshore zooplanktonare typified by species like Acartia,which are smaller, less nutritious, andapparently do not form the dense

ndangered northern right whales, when visiting Massachusetts and Cape Cod Bays, will be exposed tolower amounts of toxic pollutants and pathogens because of improved wastewater treatment. Hypothe-sized effects of nutrients on plankton that are food for the right whale are being carefully monitored.E

18Acartia

1 mm

Calanus

2.5 mm

patches required to sustain a feedingwhale. Different types of copepods eatdifferent kinds of phytoplankton. It hasbeen suggested that the nutrients dis-charged by the new outfall could causethe Bay environment to favor zooplank-ton like Acartia—not good food for rightwhales.

Another nutrient-related whale-feedingconcern is nuisance algal blooms: will theoutfall cause blooms of Phaeocystis,which seems to interfere with whale feed-ing, or brown or red tides which might betoxic? Blooms of Phaeocystis andAlexandrium have occurred in the Bays,so the question is whether the outfall

could worsen them.To help address both of these food

availability issues, MWRA has used theBays Eutrophication Model (page 16).The model shows that we can expect tosee effects of nutrient discharges limitedto the immediate area of the outfall, so itis unlikely that there would be any outfall-related changes as far away as rightwhale habitat. If any changes in phyto-plankton or zooplankton do result fromthe discharge, they would first occur nearthe outfall. Therefore, MWRA is monitor-ing intensively for changes in planktoncomposition there. MWRA also monitorsCape Cod Bay for any significantchanges.

phytoplanktonTiny floating plants (algae), especiallydiatoms, that are carried about withocean currents. These plants (illus-trated at right) grow most abundantlynear the surface of the water, wherethey receive maximum light. At thebase of the marine food web, phyto-plankton grow using nutrients in thewater, and are eaten by zooplankton.

zooplanktonTiny floating animals, including juve-nile forms of fish, jellyfish, and shell-fish. Very small crustaceans, the cope-pods (see drawings on left), are oftenabundant in zooplankton. Zooplanktoneat phytoplankton, and in turn areeaten by fish and other marine animals,including northern right whales.

plankton

Figure 22. Feeding northern right whale. High springtime nutrient levels in the water, combinedwith wind and current patterns, stimulate the abundant growth of phytoplankton and Calanus cope-pods in Cape Cod Bay and Stellwagen Bank. The nutritious copepods are found in dense patches,favored by filter-feeding northern right whales. The whales feed in Massachusetts and Cape Cod Baysin the spring before continuing their migration north to the Bay of Fundy. MWRA monitoring will detectchanges in phytoplankton or zooplankton communities. (Illustration by S. Hussey, after S. Landry, cour-tesy of New England Aquarium).

19

outfallwill we know if the

aseline monitoring, which has been conducted since 1992, is telling us a lot about natural environ-mental variability. The more we understand the Bays system, the more quickly and confidently wecan determine if an apparent impact is discharge-related. Scientists and regulators have estab-lished threshold values of environmental parameters that will trigger MWRA action.B

is causing a problem?

Permit, trigger parameters, andthresholds

MWRA’s National Pollutant Dis-charge Elimination System (NPDES)permit for the new treatment plant andoutfall, to be issued jointly by EPA andthe Massachusetts Department ofEnvironmental Protection (DEP), willincorporate stringent limits and testingrequirements for Deer Island effluentdischarges. The permit will be one ofthe most comprehensive and protec-tive permits ever issued, and willrequire that state and federal waterquality criteria not be violated as aresult of the discharge. In addition,MWRA has been conducting an exten-sive outfall monitoring program, whichis linked to an action plan—the Contin-gency Plan—that incorporates triggerparameters and threshold values forMWRA actions.

Trigger parameters are environmen-tally significant components of effluentor the marine ecosystem that, if certain(threshold) levels are exceeded, indi-cate a potential for environmental risk.Examples of trigger parameters foreffluent are total suspended solids,biochemical oxygen demand, and toxiccontaminants. Examples of environ-mental trigger parameters are watercolumn dissolved oxygen concentra-tion, chlorophyll a concentration, ben-thic community structure, and liver dis-

ease in flounder. Twenty-two triggerparameters are incorporated in theoutfall monitoring program.

Threshold values are measurementsof trigger parameters selected as indi-cators of the need for action, and arebased on expected permit limits, statewater quality standards, and expertopinion. To alert MWRA to anychanges, each trigger parameter hasthresholds that are defined as cautionor warning levels. These thresholdsare based on monitoring data collectedsince 1992 under the guidance of theOutfall Monitoring Task Force, whichincludes academic scientists, govern-ment agency representatives, and citi-zens groups.

Monitoring comprehensivelyYears of study by MWRA, scientists

at major universities, research institu-tions including the Woods HoleOceanographic Institution, and govern-ment agencies including the EPA andGeological Survey, have shown thatthe combination of improved waste-water treatment at Deer Island and thedilution provided by discharge of efflu-ent into deeper Bay waters will gener-ally benefit Massachusetts Bay andBoston Harbor. Nevertheless, toensure that any potential unforeseenenvironmental impacts of the outfallrelocation are addressed, MWRA has

implemented the most comprehensivemarine monitoring program in thenation for a secondary-treated sewagedischarge, and will continue post-dis-charge monitoring after the outfallbegins operating in 1998. Actions to betaken by MWRA if any unexpectedimpacts occur are detailed in the Con-tingency Plan described at the end ofthis report.

Massachusetts Bay has become oneof the most thoroughly studied marineenvironments anywhere. As recom-mended by the National Academy ofSciences’ National Research Council,the monitoring program focuses on thepotential impacts of nutrients, organicmaterial, toxic contaminants,pathogens, solids, and floating debris.Contaminants are measured and bio-logical observations made in effluent,water, sediment, plankton, fish, andshellfish. Even satellite data is used tomeasure chlorophyll, temperature, andother ocean conditions (Figure 23).

Sampling is most intensive in theimmediate discharge area (within threemiles of the diffuser). In addition, sam-pling stations more than 30 miles awayin Cape Cod Bay are included (Figure24). Since the inception of the monitor-ing program, 3.4 million data recordshave been collected and stored inMWRA’s marine monitoring database,and more than 200 reports written.

Monitoring at all scalesPerhaps the biggest challenge in pol-

lution effects monitoring is to charac-terize the natural variability in the envi-ronment. Within the general patterns ofseasonal and habitat differences, themarine environment can be unpre-dictable. Changes occur in the physi-cal and biological environment that areunrelated to human activities. Plants,animals and plankton in Massachu-setts and Cape Cod Bays have what istermed a patchy distribution in spaceand time; where and when they arefound are greatly affected by localwinds, currents, sediment types, oranimal behavior. This means we mustmeasure local changes, as well asunderstand broader, generalprocesses.

The most frequent measurementsare by moored instruments that collectdata at one location at intervals onlyminutes apart. In the critical areaaround the outfall, oceanographic ves-sels frequently collect water and sedi-ment samples for detailed chemicaland biological analyses. At sites dis-tant from the outfall location, less fre-quent sampling will enable us to moni-tor the general health of the area. Thebig, regional picture, on a scale of kilo-meters, is generated by satelliteimages.

20

This floating buoy ownedby the National Oceanicand Atmospheric Administrationcollects oceanographic data such as wave height, at the surface of the sea.Satellites like SEASTAR collect climate

data and measure parameters such as chlorophyll a over hundreds of square miles.

Tem

pera

ture

s (C

)

USGS Mooring (5m)

Ship survey (10m)

Sep Oct

These two moored instrument arrays,owned by the U.S. Geological Survey,continuously measure sediment deposition rates, ocean currents, and other parameters like temperature. The tripod (below) gathers data at the ocean floor, the instrument at right makes measurements at mid-depths.

Example of data (water temperature)collected continuously by moored instruments compared to survey data collected by ship.

Scientists on oceanographic ships collect water, plankton, fish, shellfish, and sediment samples for MWRA throughout the Bays for laboratory analysis.

Jan

20

15

10

5

0

Feb Mar Apr May Jun Jul Aug Nov Dec

Figure 23. MWRA monitors theHarbor and Bay at all scales; data arecollected by satellite, ship, and mooring.

21

Indicators of the Bays’health vary naturally

Baseline monitoring hasshown that, within theoverall seasonal cycle,there is intense variationfrom year to year. Forinstance, Figure 25 showsdifferences in abundanceof dominant (beneficial)phytoplankton and nui-sance phytoplankton in theBays since baseline moni-toring began in 1992. Themaximum abundances ofbeneficial phytoplankton,like Skeletonema andTha-lassiosira, vary relativelylittle from year to year.By contrast, nuisance phy-toplankton like red tide(Alexandrium tamarense,the cause of paralyticshellfish poisoning) orblooms that lower bay-wide oxygen concentra-tions, discolor the water, or

produce foul odors, are much moreerratic from year to year. Large nui-sance blooms are interspersed with noblooms. In 1992 and in the spring of1997 (not shown), there were large nui-sance Phaeocystis blooms in Cape CodBay and Buzzards Bay. The 1997bloom apparently interfered with rightwhale feeding, as right whales left CapeCod Bay earlier than usual that year(Mayo, 1997). Nuisance blooms can belinked to the larger circulation in theGulf of Maine: for example, winds, cur-rents and spring runoff during Maydetermine whether red tide enters

019961995199419931992

0

Max

imum

abu

ndan

ce (c

ells

/lit

er)

19961995199419931992

10

100

1,000

10,000

100,000

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00

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100,000

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10,000,000

Max

imum

abu

ndan

ce (c

ells

/lit

er) Skeletonema costatum

Asterionellopsis glacialisThalassionema nitzschioidesThallassiosira nordenskioldii

Ceratium tripos

Asterionellopsis glacialis

Phaeocystis pouchetti

Pseudo-nitzschia pungens

Alexandrium tamarense

Legend

USGS mooring

Soft sediment bottom surveys

Baseline water qualitymonitoring nearfield

Baseline water qualitymonitoring farfield

Outfall

Flounder, lobster, ormussel sampling

Figure 24. Monitoring stations include water, sediment, and the biota close to and dis-tant from the new outfall site.

Monitoring locations in the Bays.

Beneficial algal blooms

Nuisance algal blooms

Figure 25. Beneficial and nuisancealgal blooms have different inter-annual pat-terns. Nuisance algal blooms have occurredduring the baseline monitoring period. Theseblooms are less predictable than the normal,beneficial algal blooms which produce foodand oxygen. Continued monitoring willenable MWRA to detect whether changes inalgal blooms are related to the outfall (MWRAmonitoring data).

22

Massachusetts Bay or is transportedout to sea (Anderson, 1997).

Figure 26 shows another example ofnatural variability: in 1994 and 1995,average oxygen concentration in thebottom waters of the Bay fell below thecaution level. This measurement wouldtrigger more intensive evaluation oncethe new outfall comes on-line, an exam-ple of a natural phenomenon that couldhave been interpreted as outfall-related.

Another example of a measurementthat, if the new outfall were in use,could have been attributed to sewageeffluent, was a pattern of silver deposi-tion in the sediments near the new out-fall site. Figure 27 shows that silverconcentrations spiked up to more thandouble their baseline value in February1993 after an unusually severe storm inDecember of 1992. That storm causedredistribution of silver into the muddysediments sampled. By February 1994,silver concentrations declined to near-background levels. If the new outfallhad been commissioned, it might haveseemed reasonable to attribute the ele-vated silver concentration to the outfall,but now we know that severe stormscan create a pattern like this one.

Observations of natural year-to-yearvariation of phenomena like nuisanceblooms and the spike of silver in thearea near the outfall site provide animportant context for examiningchanges after the long outfall is com-missioned. Information like this will helpMWRA, scientific experts, regulators,and interested citizens to know whereto look for likely causes of suspectedenvironmental problems.

0

0.5

1

1.5

2

Ap

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9

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once

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tion

(par

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ep-9

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Major stormDecember 1992

Figure 26. Baseline monitoringshows low dissolved oxygen can occurin bottom waters at the future outfallsite. Average dissolved oxygen levels measured dur-ing surveys of the bottom waters of theoutfall nearfield area show dramaticseasonal fluctuations, as well as varyingfrom year to year. In 1994, the averageDO in October almost violated the statewater quality standard, and did fallbelow the caution (6.5 mg/l) level in1994 and in 1995. Another measure-ment, the percent saturation of DO, notshown, violated the warning level in1994 and 1995. These violations arerelated to the warmer temperaturesduring those years; in the post-dis-charge period such low levels wouldtrigger notification of the Outfall Moni-toring Task Force (error bars representone standard deviation; MWRA moni-toring data).

Sediment silver concentrations at the Bay outfall site (1989-1996)Figure 27. Silver concentrations insediment near the future outfall siteincreased after a major storm. A majorstorm occurred in December 1992,causing resuspension of sediments fromshallower inshore areas, which rede-posited into deeper offshore areas,including a small muddy area near thefuture outfall site (average is mean ofthree measurements error bars showone standard deviation; data fromBothner 1997 in press, Bothner et al.1997 in press).

Apr Jul Oct1992

Apr Jul Oct1993

Apr Jul Oct1994

Apr Jul Oct1995

Apr Jul Oct1996

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Ave

rage

dis

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xyge

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g/l)

(Water quality standard)Warning level

Caution level

Dissolved oxygen levels in bottom water at the Bay outfall site

23

what will if a problem occurs?

he Contingency Plan describes how, if monitoring results indicate apossible environmental problem, MWRA and the regulatory agencieswill act to determine the cause of the problem and what correctiveactions should be taken.T

The Outfall Contingency PlanThe Outfall Contingency Plan was

developed to create a process to iden-tify and respond to water qualitychanges that potentially could berelated to effluent discharges. Eventhough it is not expected that these dis-charges will affect the environmentadversely, the Contingency Plandescribes the criteria and process thatMWRA, regulatory agencies, and theOutfall Monitoring Task Force (OMTF)would use to assess potential changes,make information on those changesavailable to the public, and respondappropriately to avoid harm to themarine environment.

How the Contingency Planworks

The Contingency Plan identifies trig-ger parameters, conditions that cansuggest that effluent quality or environ-mental conditions may be changing orlikely to change in the future. To alertMWRA to different degrees of observedchange, each trigger parameter hasthresholds that are defined as cautionor warning levels. These thresholds arebased on monitoring data collectedsince 1992.

In the event that a threshold isexceeded, the process for respondingwill vary somewhat depending onwhether the threshold is a caution or a

more serious warning level (Figure 28).The response to any thresholdexceedance, even before the causehas been discovered, will be to decidewhether treatment plant operations canbe altered to reduce the discharge ofthe relevant pollutant.

If MWRA discharges have caused acaution level to be exceeded, MWRAwill expand its monitoring to closelytrack any change in effluent quality andenvironmental conditions, and providethe information necessary to:1) evaluate the cause and effect of the

exceedance; and2) review applicable trigger parameters

and thresholds.

If the threshold exceeded is a warn-ing level, the proposed response willinclude both early notification to EPAand DEP and the quick development ofa Response Plan. A Response Planincludes a schedule for implementingactions such as additional monitoring,making further adjustments in plantoperations, or undertaking an Engineer-ing Feasibility Study regarding specificpotential corrective activities.

Corrective activitiesCorrective activities have been identi-

fied in the Contingency Plan (or may beidentified in the future) as potential solu-tions to unexpected impacts in the

marine ecosystem from the operation ofthe outfall. If the effects of effluent dis-charges must be reduced, examples ofcorrective activities could include theaddition of specific enhanced treatmenttechnologies and increased pollutantprevention and regulation.

How the Contingency Plan is accountable to the public

To ensure that the Contingency Planprovides appropriate environmental pro-tection, every step of the implementa-tion process will be open to public inputand review. In addition, MWRA will pro-duce a quarterly Wastewater Perfor-mance Report to provide the public withinformation about plant performanceand monitoring results. The report isdesigned to:

• provide information about key waste-water operations;

• demonstrate day-to-day progress inachieving goals and objectives; and

• compare actual performance againsttrigger parameters and other impor-tant water quality monitoring or plantperformance targets.

Once a year, MWRA will also developan Outfall Monitoring Overview/Contin-gency Plan report that will be submittedto the Outfall Monitoring Task Force aswell as to EPA, DEP, and the Federal

Court. The report will also be availableto the public. The report will summarizemonitoring results and anyexceedances, responses related to theContingency Plan, and corrective activi-ties that have occurred over the previ-ous year. The report will also proposechanges to the Contingency Plan, asneeded. Changes are expected to beguided primarily by OMTF recommen-dations.

How the Contingency Plan will be enforced

The Contingency Plan is one portionof many obligations, both state and fed-eral, that MWRA is required to meet:

• The NPDES permit imposes extensiverequirements on MWRA discharges,including effluent monitoring, report-ing, plant maintenance and opera-tions, and the industrial pretreatmentprogram. Requirements for the com-bined sewer overflow (CSO) programand sludge-to-fertilizer plant are alsoincluded;

• A Federal Court Order guides the con-struction of the new treatment facili-ties, sludge-to fertilizer plant, CSOprojects, and the industrial pretreat-ment program, as well as treatmentplant staffing;

• The Massachusetts Executive Officeof Environmental Affairs and EPAhave overseen the development andimplementation of MWRA’s Outfall

be done

24

Monitoring Plan, which has also beensubmitted to the Federal Court.

To ensure that even greater over-sight and enforcement opportunitiesare provided, the new draft NPDESpermit being developed for public com-ment by EPA and DEP is expected toinclude requirements to ensure that theContingency Plan will be implementedas described and intended.

The Contingency Plan is designedto build on and be consistent withMWRA’s regulatory and judicial oblig-ations. The Plan also represents thematching of MWRA’s obligations witha clear line of accountability to theCourt, regulatory agencies, and thepublic.

OMSAP Confirms CautionLevel Exceedance

Ongoing Monitoring

Preliminary DataReported to MWRA

Caution Level

Exceeded?

Notify Plant Staff & OMSAPAdjust Operations

if Needed

Warning Level

Exceeded?

YES

YES

NO

NO Accelerate DataConfirmation

Annual Monitoring Report

Caution Level ExceedanceReported in Quarterly

Wastewater Performance Report

MWRA DevelopsResponse Plan

OMSAP Confirms WarningLevel Exceedance

Evaluations Actions and Follow-up Reported in Quarterly

Wastewater Performance Report

Schedule

5 days

30 days

90 days

180 days

Exceedance and Response Plan Reported in QuarterlyWastewater Performance

Report

Figure 28. Contingency plan process flowchart

In 1990, the Massachusetts Secretary of Environmental Affairs formedthe Outfall Monitoring Task Force (OMTF) to advise the MWRA. TheOMTF, composed of scientists and representatives from governmentagencies and regional environmental groups, guides MWRA’s monitor-ing program. The Task Force directed MWRA to monitor in four generalareas: effluent, water column, sediment, and living resources. TheOMTF meets regularly to review MWRA’s findings and approveschanges in monitoring annually based on new scientific information.The Task Force also sets priorities regarding the environmental issuesand questions MWRA should address with its monitoring program.OMTF meetings are open to the public.

task forceoutfall monitoring

25

endnotes for Table 2

1 Maximum value measuredduring Deer Island detailedeffluent studies (Butler et al.1997), except for totalPCBs, which are averagevalues.

2 Secondary effluent fromDeer Island pilot secondaryplant.

3 After appropriate dilutionfactor (80:1 for copper, leadand mercury available inarea nearest diffuser, afterinitial mixing. Dilution factoris 364:1 for DDTs, PAH, andPCBs, available in the out-fall nearfield area.)

4 EPA determines three cate-gories of receiving waterquality criteria: acute,chronic, and human health.Different criteria are appliedto different types of dis-charges. Acute criteria areapplied to small areas orbrief discharges, and specifythe maximum concentrationof a constituent an organismcan be safely exposed to fora short duration. Chronic cri-teria are applied to largeareas or long-term dis-charges and specify themaximum concentration of aconstituent that an organismcan be safely exposed to fora long period of time.Human health criteria reflectthe concentration of a con-stituent that fish and shell-fish can live in without

endangering the health ofpeople who eat the seafood.

5 Water quality criteria forcopper, mercury and leadare EPA chronic criteria.Water quality criteria forDDTs, PAH and PCBs arehuman health criteria.

6 The criterion for fluoran-thene is given becausethere is no established crite-rion for total PAH.

7 Comparing PCBs in effluentto the water quality criterionis problematic becauseambient levels in all Massa-chusetts waters already vio-late the human health stan-dard.

references

• Anderson, D. M., B. A.Keafer, and J. T. Turner.1997. ‘Red tides’ in Massa-chusetts Bay: Nearshoreprocesses and transfer oftoxins through the pelagicfood web. Report to MWRA.

•Bitton, Gabriel. 1994. Waste-water microbiology.Wiley-Liss, Inc. New York. 478pp.

• Bothner, M. H., 1997, Metalconcentrations in sedimentsof Boston Harbor documentenvironmental change.USGS Fact Sheet, 97-xxx,2p. in press.

• Bothner, M. H., M. Buchholtz

ten Brink, and F.T. Man-heim, 199X, Metal concen-trations in surface sedi-ments of BostonHarbor–changes with time.Marine EnvironmentalResearch, in press.

• Bothner, M. H., M. Buchholtzten Brink, C. M. Parmenter,W. M. d’Angelo, and M. W.Doughten. 1993. The distri-bution of silver and othermetals in sediments fromMassachusetts and CapeCod Bays-—an interimcompilation. U.S. Geologi-cal Survey. Open file report93-725.

• Bousfield, E.L. 1973. Shal-low-water GammarideanAmphipoda of New Eng-land. Cornell Univ. Press,Ithaca and London. 321 pp.

•Butler, E., M. Higgins, J. Chi-apella, and W. Sung. 1997.Deer Island effluent charac-terization studies: January1995-December 1995.MWRA Enviro. QualityDept. Tech Rpt. Series No.97-3. MWRA, Boston MA.91 pp.

• Cibik, S.J., B. L. Howes, C.D. Taylor, D. M. Anderson,C. S. Davis, and T. C. LoderIII. 1996. 1995 Annual watercolumn monitoring report.MWRA Enviro. QualityDept. Tech Rpt. Series No.96-7. MWRA, Boston MA.241 pp.

• Coats, D. A. 1995. 1994Annual soft-bottom benthicmonitoring: MassachusettsBay outfall studies. MWRAEnviro. Quality Dept. TechRpt. Series No. 95-20.MWRA, Boston MA. 184pp.

• Galya, D. P. , J. Bleiler, andK. Hickey. 1997. Outfallmonitoring overview report1995. MWRA Enviro. Qual-ity Dept. Tech Rpt. SeriesNo. 97-2. MWRA, BostonMA. 48 pp.

• Hilbig, B., J. A. Blake, E.Butler, D. C. Rhoads, G.Wallace, and I. P. Williams.1996. Benthic biology andsedimentology: 1995 base-line conditions in Massa-chusetts and Cape CodBays. MWRA Enviro. Qual-ity Dept. Tech. Rpt. SeriesNo. 96-5. MWRA, BostonMA. 230 pp.

• Hilbig, B., J. A. Blake, D. C.Rhoads, and I. P. Williams.1996. Boston Harbor soft-bottom benthic monitoringprogram: 1995 results.MWRA Enviro. QualityDept. Tech. Rpt. Series No.96-8. MWRA, Boston MA.94 pp.

• Hillman, R.E. and C.S.Peven. 1995. 1994 annualfish and shellfish report.MWRA Enviro. QualityDept. Tech. Rpt. Series No.95-5. MWRA, Boston, MA.

82 pp.

• Hydroqual, Inc. and Norman-deau Associates, Inc. 1995.A water quality model forMassachusetts and CapeCod Bays: calibration of theBays Eutrophication Model(BEM). MWRA Enviro.Quality Dept. Tech. Rpt.Series No. 95-8. MWRA,Boston MA. 402 pp.

• Hull, R. N. and G. W. Suter.1995. Toxicological bench-marks for screening conta-minants of potential concernfor effects on sediment-associated biota: 1994 revi-sion. Oak Ridge NationalLaboratory ReportES/ER/TM-95/RI. 28 pp.

• Long, E. R. and L. G. Mor-gan. 1990. The potential forbiological effects of sedi-ment absorbed contami-nants tested in the NationalStatus and Trends Program.NOAA. Technical Memoran-dum NOS OMA 52. U. S.National Oceanic andAtmospheric Administration,Seattle, Washington. 175pp.

• Long, E. R., D. D. MacDon-ald, S. L. Smith, F. D.Calder. 1995. Incidence ofadverse biological effectswithin ranges of chemicalconcentrations in marineand estuarine sediments.Environmental Manage-ment. 19 (1):81-97.

referencesendnotes

26

• Massachusetts Bays Pro-gram,1996. The Massachu-setts Bays 1996 Compre-hensive Conservation andManagement Plan: anEvolving Plan for Action.Mass. Executive Office ofEnvironmental Affairs,Boston, MA.

• Massachusetts WaterResources Authority. 1991.Effluent outfall monitoringplan phase I: baseline stud-ies. MWRA Enviro. QualityMiscellaneous Rpt. SeriesNo. ms-2. MWRA, BostonMA. 95 pp.

• Massachusetts WaterResources Authority. 1995.Effluent outfall monitoringplan phase II: post dis-charge monitoring (draft).MWRA Enviro. Quality Draft11/95. MWRA, Boston MA.

• Massachusetts WaterResources Authority. 1997.Contingency Plan. February1997. 41 pp.

• Mayo, Charles. 1997. Foodresources and foragingimperatives of the northernright whale Eubalaenaglacialis in Massachusettsand Cape Cod Bays.Abstract in Conference Proceedings vol 1, CoastalZone ‘97.

• Mitchell, D. F., T. Mounce, J.Morton, K. Sullivan, M.Moore, and P. Downey.1996. 1995 Annual fish andshellfish report. MWRAEnviro. Quality Dept. TechRpt. Series No. 96-3.MWRA, Boston MA. 112pp.

• Mitchell, D. F., M. Wade, W.Sung, and M. Moore. 1997.1996 Toxics issues review.MWRA Enviro. QualityDept. Tech Rpt. Series No.97-4. MWRA, Boston MA.134 pp.

• Murchelano, R. A. and R. E.Wolke. 1985. Epizootic car-cinoma in winter flounderPseudopleuronectes ameri-canus. Science 228:587-589.

• National Marine FisheriesService. 1991. Recoveryplan for the northern rightwhale (Eubalena glacialis).Prepared by the RightWhale Recovery Team forthe National Marine Fish-eries Service, Silver Spring,MD. 86 pp.

• National Marine FisheriesService. 1992. MarineMammal Investigation. Theright whale in the westernNorth Atlantic: A scienceand management work-shop. Northeast Fisheries

Science Center ReferenceDocument 92-05. 87 pp.

• National Marine FisheriesService. 1995. MarineMammal Investigation. Anindependent scientific peerreview of North Atlanticright whale research sup-ported by the NortheastFisheries Science Center: Aworkshop held in WoodsHole, Massachusetts, Octo-ber 3-7, 1994. Woods HoleMA: NOAA/NMFS/NEFSC.Center Ref. Doc. 95-01. 30pp.

• National Research Council.1993. Managing waste-water in coastal urbanareas. National Academy ofSciences, National Acad-emy Press, WashingtonD.C.

• Pawlowski, C., K.E. Keay, E.Graham, D.I. Taylor, A.C.Rex and M.S. Connor.1996. The State of BostonHarbor 1995: The newtreatment plant makes itsmark. MWRA Enviro. Qual-ity Dept. Tech Rpt. SeriesNo. 96-6. MWRA, BostonMA. 22 pp.

• Schwartz, J.P., N.M. Duston,and C.A. Batdorf. 1993.Metal concentrations in win-ter flounder, American lob-ster, and bivalve molluscs

from Boston Harbor, SalemHarbor, and coastal Massa-chusetts. EOEA and MADFWELE.

• Schwartz, J.P., N.M. Duston,and C.A. Batdorf. 1991.PCBs in winter flounder,American lobster, andbivalve molluscs fromBoston Harbor, Salem Har-bor, and coastal Massachu-setts: 1984-1989. EOEAand MA DFWELE Publica-tion 16, 966-63-250-W-91-C.R.

• Shea, D. 1993. Annualreview of toxic contami-nants discharged byMWRA. MWRA Enviro.Quality Dept. Tech Rpt.Series No. 93-18. MWRA,Boston MA. 68 pp.

• Shea, D. 1995. Multimediafate model of organic conta-minants in MassachusettsBay. MWRA Enviro. QualityDept. Tech Rpt. Series No.95-18. MWRA, Boston MA.15 pp.

• Signell, R. P., H. L. Jenter,and A. F. Blumberg. 1996.Circulation and effluent dilu-tion modeling in Massachu-setts Bay: model implemen-tation, verification andresults. U. S. GeologicalSurvey Open File Report96-015.

• USEPA.1989. Assessinghuman health risks fromchemically contaminatedfish and shellfish. EPA Doc-ument No. EPA-503/8-89-002. Office of Marine andEstuarine Protection (WH-556F) and the Office ofWater Regulations andStandards (WH-552).Washington, DC.

27

28

mwraInformation about the MWRAhttp://www.mwra.state.ma.us

state and federalMass. Division of Marine Fisherieshttp://www.magnet.state.ma.us/dfwele/dmf/dmf_toc.htm

Mass. Executive Office of EnvironmentalAffairs (EOEA)http://www.magnet.state.ma.us/envir/eoea.htm

Departments within EOEA(DEM, DEP, DFWELE, DFA, MDC)http://www.magnet.state.ma.us/envir/depts.htm

Northern right whale information http://www.magnet.state.ma.us/envir/rtwhale.htm

Program Offices of EOEA (MCZM,MEPA, DCS, OTA, MassGIS, STEP)http://www.magnet.state.ma.us/envir/units.htm

MDC beach water quality http://www.magnet.state.ma.us/mdc/harbor.htm

MDC guide to Boston area reservations,including coastal and Harbor island sites.http://www.magnet.state.ma.us/mdc/reserv.htm

Boston Harbor Islands National Recre-ation Area http://www.nps.gov/boha/

EPA Region 1http://www.epa.gov/region01/National Marine Fisheries Service - North-east Regional Office, Gloucester MAhttp://www.wh.whoi.edu/ro/doc/nero.html

USGS Woods Hole Field Centerhttp://woodshole.er.usgs.gov/

Boston Harbor - Mass. Bay Ecosystems- Sediment Bibliographyhttp://coast-enviro.er.usgs.gov/MassBib/default.htm

Boston Harbor Ecosystems - USGS,New England Aquariumhttp://coast-enviro.er.usgs.gov/boseco/

Coastal Ocean Modeling at the USGSWoods Hole Field Centerhttp://crusty.er.usgs.gov/

A Geologic Map of the Sea Floor inWestern Massachusetts Bay,Constructed from Digital Sidescan-Sonar Images, Photography,and Sediment Sampleshttp://woodshole.er.usgs.gov/data1/CDROMS/massbay.dds3/massbay.html

Gulf of Maine Information Systemhttp://oracle.er.usgs.gov/GoMaine/

Gulf of Maine Red Tideshttp://crusty.er.usgs.gov/wgulf/wgulf.html

Ocean engineer Marinna Martini’s webpage on oceanography tools.http://marine.usgs.gov/~mmartini/instment/tools.htm

USGS Branch of Atlantic Marine Geol-ogy, Sediment Databasehttp://woodshole.er.usgs.gov/

data1/SEDIMENTS/hathaway/readme.1st.htm

USGS Contaminant Transport Studiesin Massachusetts Bayhttp://crusty.er.usgs.gov/mbay/mbay.html

USGS Stellwagen Bank InformationSystemhttp://vineyard.er.usgs.gov/

Northeast Fisheries Science Center -Woods Holehttp://www.wh.whoi.edu/noaa.html

advocacy groupsThe Boston Harbor Associationhttp://www.tbha.org/

Center for Coastal Studies, ProvincetownMAhttp://www.provincetown.com/coastalstudies/index.html

Charles River Watershed Associationhttp://www.crwa.org/

Merrimack River Watershed Associationhttp://www.merrimack.org/

National Resources Defense Council:Testing the Waters 1997 - Howdoes your vacation beach rate?http://www.nrdc.org/nrdcpro/ttw/summas.html

Neponset River Watershed Associationhttp://www.walpole.ma.us/nepon-set.htm

Safer Waters In Massachusetts, Inc. http://www.nahant.org/swim/html

Save the Harbor / Save the Bay http://www.tiac.net/users/shsb/index.html

educationReferences, documents, and data pertain-ing to the Mass. Bay ecosystem. http://massbay.mit.edu/

MIT Mass Bay research bibliographyhttp://opal-www.unh.edu/edims.html

Digital Orthophotos of Boston Harbor andsurrounding area - MASS GIS, MIThttp://ortho.mit.edu/

Gulf of Maine Council on the Marine Envi-ronment - Environmental Dataand Information Management System(EDIMS)http://massbay.mit.edu/bibliography.html

New England Aquariumhttp://www.neaq.org/

Cetacean Research Unit - research, edu-cation, conservationhttp://www.friendly.net:80/user-homepages/b/birdman/

other organizationsNew England Water Environment Associ-ation (NEWEA)http://www.newea.org/

Northeast Business Environmental Net-work (NBEN)http://nben.org/index.html

web sitesinternet

1 0 0 F i r s t A v e n u eC h a r l e s t o w n N a v y Y a r d

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