1994 overview

Massachusetts Water Resources Authority · from the MWRA · 51 pages · 8.0 MB
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OUTFALL MONITORING OVERVIEW REPORT: 1994 - MWRA ,

Prepared by:

Donald P. Galya — ENSR
John Bleiler — ENSR
Kenneth Hickey — ENSR

Additional Contributions and Suggestions by:

Michael S. Connor — MWRA
Michael Mickelson — MWRA
Kenneth Keay — MWRA
Wendy Smith Leo — MWRA
Maury Hall — MWRA
Steven Cibik — ENSR

David Mitchell — ENSR
Isabelle Williams — ENSR
James Blake — ENSR

James Bowen — ENSR
Joshua Lieberman — ENSR
Susan McCarthy — ENSR
Steven Wolf — ENSR

Karen Hopkins — ENSR

Report Layout and Graphics by:

Kim Loosen — ENSR
Ilse Stryjewski — ENSR
Gavin Gong — ENSR

Citation:
Galya, D-P., J. Bleiler, and K. Hickey. 1996. Outfall Monitoring Overview

Report: 1994. MWRA Enviro. Quality Dept. Tech. Rpt. Series No. 96-4.
Massachusetts Water Resources Authority, Boston MA. 50 pp.

MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1994 /I

Table of Contents

Executive Summary

Wastewater Effluent Monitoring

Waiter Column Monitoring Program
Benthic Studies

Fish and Shellfish Monitoring Program

1.0 Introduction

1.1 Background © 20 2..eee d 01
1.2 Reasons for Monitoring ... 0.2... 0.66! Ol
1.3 Monitoring Program History/Status.... 0.00.00. 02
1.4 Monitoring Program Objectives ......0... 00.0000 eee eee eed 02
1.5 Wastewater Constituents of Environmental Concern...................4 03
1.6 Report Objectives and Organization ©... 04

2.0 Nutrients

2.1 Water Quality/Biological Issues 20.2... eee ed 05
2.2 Trigger Parameters and Thresholds .. 2.2... 06
2.3 Monitoring Program Components Designed to Address Issues ............J 09
2.4 Monitoring Program Results... 0.0... eee 10

3.0 Organic Material

3.1 Water Quality Issues 2.0. ee 15
3.2 Trigger Parameters and Thresholds ..............00 0.20000 c eee ee eee 15
3.3 Monitoring Program Components Designed to Address Issues ............. 15
3.4 Monitoring Program Results... 2.006. 16

4.0 Toxic Contaminants

4.1 Water Quality Issues 2.0. ee 17
4.2 Trigger Parameters and Thresholds 0.0... 0.2... ee 17
4.3 Monitoring Program Components Designed to Address Issues ............. 17
44 Monitoring Program Results... ee 19
5.0 Human Pathogens
5.1 Water Quality/Health Issues 0 ee 27
5.2 Trigger Parameters and Thresholds... 0... ee 27
5.3 Monitoring Program Components Designed to Address Issues ............. 27
5.4 Monitoring Program Results... 2.0. eee 28

II / OUTFALL MONITORING OVERVIEW REPORT: 1994 + MWRA

6.0 Solids

6.1 Water Quality Issues 20 eee 29
6.2 Trigger Parameters and Thresholds... 0... ed 29
6.3 Monitoring Program Components Designed to Address Issues ............. 29
6.4 Monitoring Program Results 2... eee 30

7.0 Floatables

7.1 Water Quality Issues 0. eee 33
7.2 Trigger Parameters and Thresholds ...............000. 00.0000 c ees 33
7.3 Monitoring Program Components Designed to Address Issues ............. 33
7.4 Monitoring Program Results... 2... ee 33

8.0 Summary of Monitoring Program

8.1 Effluent Monitoring 6... 002. 35

8.2 Water Column Monitoring 6.6... ee 35

83 Benthic Studies... 0... eee 38

8.4 Fish and Shellfish Monitoring Program ...... 0.2.22 40

8.5 Monitoring Program Database ...........0020 0.000 4

8.6 Conclusion... 6... eee 4
References

Acronym Symmary

Executive Summary

The people of the metropolitan Boston area, through the MWRA, are in the midst of an
ambitious program to upgrade their sewage treatment facilities and improve the quality of
Boston Harbor. This program includes the elimination of sludge discharges into the har-
bor, construction of new primary and secondary sewage treatment plants, and relocation
of the current Boston Harbor effluent discharge point to a new location in Massachusetts
Bay. The new Deer Island primary treatment facility went on-line in January 1995, suc-
cessive phases of the secondary treatment facilities will begin operating in late 1996, and
the new effluent discharge outfall is expected to be operational in 1998.

A number of concerns have been raised regarding potential environmental impacts associat-
ed with the relocation of the wastewater discharge to Massachusetts Bay. An Outfall
Monitoring Program was developed in order to assure that these concerns are addressed.
This program consists of two main phases. Baseline Studies which commenced in 1992
are currently underway to document conditions before outfall relocation. Post-Discharge
Monitoring will commence in 1998; these studies will evaluate conditions after the new
outfall is operational. This report describes the baseline monitoring program, summarizes
and discusses the program results through 1994, and summarizes Post-Discharge
Monitoring warning and action levels.

Both phases of monitoring evaluate six categories of wastewater constituents: Nutrients,
Organic Material, Toxic Contaminants, Pathogens, Solids, and Floatables. These six parame-
ters were evaluated in four different environmental measurement areas: Effluent, Water
Column, Benthic Environments, and Fish and Shellfish. The overall monitoring program is
summarized on Table ES-1.

Wastewater Effluent Monitoring

Wastewater Effluent from the treatment plant is routinely evaluated to ensure that dis-
charged effluent meets required standards.

The Baseline effluent monitoring program has included monitoring of nutrients, organic
material, toxic contaminants, pathogens, solids, and oil and grease. Effluent monitoring has
demonstrated that improvements made to the MWRA system during the last few years have
generally resulted in substantial improvements in wastewater effluent quality. As the
MWRA upgrades to secondary treatment of sewage, continued improvement of effluent
quality will result in compliance with federal secondary treatment standards and
Massachusetts water quality standards.

Water Column Monitoring Program

The Water Column monitoring program is designed to measure water quality in
Massachusetts and Cape Cod Bays. Based on extensive predictive modeling studies,
changes in water quality due to outfall relocation are expected to be minimal in
Massachusetts and Cape Cod Bays. Detectable changes in water quality are expected to
occur only in the immediate vicinity of the outfall. The water column monitoring program
provides a basis for detecting changes in water quality and plankton resulting from the relo-

ii / OUTFALL MONITORING REPORT: 1994 MWRA

TABLE ES-1
Summary of MWRA Monitoring Program

Objective

Sampling Locations and Schedule

Analyses

Effluent Sampling

Characterize wastewater
discharged from Deer Island
Treatment Plant

EFFLUENT MONITORING

* Monthly * Nutrients

* Daily * cBOD

* Monthly * Toxic contaminants
* 3Times/Day * Pathogens

* Daily * Solids

© Weekly ° Oil & Grease

© Weekly * Floatables

WATER COLUMN MONITORING

throughout Massachusetts

26 locations (See Figure 2-4)

Nearfield Surveys Collect water quality data * 17 surveys/year * Temperature * Nutrients
near outfall location * 21 locations (See Figure 2-4) * Salinity * Total Suspended
* Dissolved oxygen Solids
* Chlorophyll * Plankton
Collect water quality data * 6 surveys/year * Temperature * Salinity

* Dissolved oxygen * Nutrients

and Cape Cod Bays * Chlorophyll « Plankton
Farfield Surveys * Total suspended
solids
Plume Track Surveys | Track location and * 3-4 surveys/year * Salinity
characteristics of * Temperature
discharge plume * Dissolved oxygen

* Chlorophyll
* Total suspended solids

Continuous
Monitoring

Provides continuous
water quality data
near outfall

* Continuous monitoring
* Single station
* 3 depths

* Temperature
* Salinity
* Optical beam transmittance

Remote Sensing

Nutrient Flux Surveys

Evaluate outfall impacts
on a regional scale
through satellite imagery

Evaluate nutrient interactions

* Approximately 1/month

BENTHIC MONITORING

« 5 surveys/year

* Temperature
* Chlorophyll

* Oxygen demand

communities in rock
and cobble areas

* 6 transects (See Figure 8-5)

SH AND SHELLFISH MONITORING

between the sediment * 7 locations (See Figure 8-2) * Nutrient flux
and water column * Porewater nutrients
Soft Bottom Surveys Evaluate sediment quality * 8 Boston Harbor stations * Sediment chemistry
in Boston Harbor (See Figure 8-3) * Benthic community composition
and Massachusetts Bay * 20 neartield stations (See Figure 8-4)
* 11 farfield stations (See Figure 8-4)
Hard Bottom Surveys | Characterize marine * 1 survey/year * Topography

* Substrate
« Benthic community composition

condition and short-term
contaminant bioaccumulation

* 3 locations (See Figure 4-2)

Flounder Studies Determine contaminant * 1 survey/year * Tissue contaminant concentrations
body burden and * 5 locations (See Figure 4-2) * Physical abnormalities
population heaith (including histopathology)

Lobster Studies Determine contaminant * 1 survey/year * Tissue contaminant concentrations
body burden * 3 locations (See Figure 4-2) * Physical abnormalities

Mussel Studies Evaluate biological * 1 survey/year * Tissue contaminant concentrations

* Physical abnormalities

MWRA + OUTFALL MONITORING REPORT: 1994 / iii

cation of the effluent outfall. It also provides a basis for monitoring potential food chain
effects on endangered species, such as humpback and right whales.

A number of different parameters are evaluated in the baseline water column monitoring
program. Studies are underway to gather baseline information on nutrient levels, tempera-
ture, salinity, and dissolved oxygen in the marine system. Other water column studies eval-
uate the presence of sensitive biological indicators such as algae. The baseline water col-
umn monitoring program has demonstrated that the Massachusetts and Cape Cod Bay sys-
tem is dynamic, with considerable spatial and temporal variability. Nutrient and chloro-
phyll (representing algae density) concentrations are highest in coastal waters near Boston
Harbor and decrease with increasing distance offshore. Seasonal algal bloom trends are sig-
nificantly different between Massachusetts and Cape Cod Bays, indicating that these ecolog-
ical systems behave somewhat independently. Dissolved oxygen values vary seasonally,
with the highest values measured during the winter, and the lowest occurring in bottom
waters in the summer. In 1994, several dissolved oxygen measurements in bottom waters
in the area of the future outfall were below state water quality standards. The influence of
seasonal cycles and differing ecological environments must be considered when evaluating
the potential influence of the MWRA upgrades within this marine system.

Benthic Studies

Benthic Studies are designed to evaluate the sea floor environment in Boston Harbor and
Massachusetts and Cape Cod Bay. Benthic studies provide a means to document recovery
of Boston Harbor following improvements to the MWRA system. These studies are also
designed to assess potential impacts to the Massachusetts and Cape Cod Bay sea floor
resulting from relocation of the outfall.

The ongoing baseline benthic monitoring program has provided valuable information on the
current status of the benthic environment in the system. Studies are underway to evaluate
benthic ecological communities and sediment quality. The complex physical environment
in Massachusetts Bay, especially near the future outfall, makes the assessment of the benth-
ic environment particularly challenging. In general, the benthic sedimentary environment,
or habitat, in the area of the future outfall is highly diverse, with large variability in sedi-
ment type over relatively short distances. Benthic biological communities appear to demon-
strate similar variability, reflecting a strong influence of sediment type on the benthic com-
munity characteristics. In addition, the benthic environment in the vicinity of the future
outfall is highly changeable, with dramatic shifts in both sediment type and benthic organ-
isms occurring after storm events.

Fish and Shellfish Monitoring Program

The Fish and Shellfish monitoring program focuses on key natural resources in the marine
environment. This program evaluates potential risks to human health and the environment
from contamination in fish and shellfish. Fish and shellfish studies provide a basis for eval-
uating recovery of natural systems following MWRA upgrades.

The baseline fish and shellfish monitoring program has included studies of mussels, floun-
der, and lobster. In general, contaminant concentrations are higher in fish and shellfish

iv / OUTFALL MONITORING OVERVIEW REPORT: 1994 + MWRA

from Boston Harbor than from the future outfall site. Contaminant concentrations in fish
and shellfish from a site in Cape Cod Bay are consistently lower than at the other sites.
Fish and shellfish contaminant concentrations have generally decreased in Boston Harbor
over the past years. In contrast, at the future outfall site, concentrations of several contami-
nants in fish and shellfish increased in 1994 compared to previous years. Nevertheless,
contaminant concentrations in fish and shellfish at all sites have consistently been well
below levels that might cause any concern because of human consumption. The contami-
nant levels have apparently caused tumors and other physical abnormalities in flounder, as
the data indicate that the prevalence of tumors increases with increasing contaminant con-
centration. As secondary treatment is phased in, and as effluent and water quality contin-
ues to improve in Boston Harbor and the Bays, it is anticipated that the health of the fish
and shellfish populations will continue to improve.

The MWRA’s Baseline Outfall Monitoring Program has gathered considerable information
documenting the existing conditions in Boston Harbor, Massachusetts Bay, and Cape Cod
Bay. Scientific data collected during the last few years reflect current levels of sewage
treatment. As improvements are made to the MWRA sewage treatment process, the
extensive economic, aesthetic, and ecological resources of this unique marine system are
expected to benefit.

MWRA : 0 L MONITORING OVERVIEW REPORT: 1994 / 01

1.0 INTRODUCTION

1.1 Background

In 1986 the Massachusetts Water Resources Authority (MWRA) initiated a program to end
longstanding violations of the Clean Water Act associated with the discharge of sewage
sludge and effluent in Boston Harbor. This program included the elimination of sludge dis-
charges into the harbor, construction of new primary and secondary treatment plants, and
the relocation of the treated effluent discharge point. The new effluent discharge location
is 9.5 miles offshore in Massachusetts Bay (Figure 1-1). The new outfall should be opera-
tional in 1998.

The U.S. Environmental Protection Agency (EPA) assessed the potential impacts associated
with the discharge of MWRA's wastewater effluent into Massachusetts Bay. This study is
discussed in the 1988 project Supplemental Environmental Impact Statement (SEIS). EPA
performed a water quality modeling study to evaluate pollutant transport in the bays and
potential water quality changes due to the wastewater discharge. The magnitude and loca-
tion of the potential water quality impacts were predicted and evaluated. In addition, bio-
logical impacts on endangered species, such as the North Atlantic Right Whale, and other
threatened marine species were assessed in the EPA's Biological Assessment and the
Nationa! Marine Fisheries Service's Biological Opinion. It was determined that there would
not be significant water quality or biological impacts associated with the project.

1.2 Reasons for Monitoring

Even though the SEIS projected minimal impacts from the relocated, cleaner discharge, con-
cerns remained with respect to the potential environmental effects associated with the relo-
cation of the wastewater discharge to Massachusetts Bay. In the SEIS Record of Decision,
the EPA required the
development of a moni-
toring program to estab-
lish baseline conditions
of the Mass-

achusetts and Cape Cod
Bay ecosystem and mea-
sure any future impacts
on the system due to
outfall relocation. The
Certificate issued by the
Massachusetts Executive
Office of Environmental
Affairs (EOEA) on the
Secondary Treatment
Facilities Plan/Final
Environmental Impact
Report (STFP/FEIR) in
1988 contained a similar
requirement.

_X New Outfall |
YK Existing Outtalls
i |

anise

a2s00'00"

Cape Cod |
Bay

‘1*00'00" o%4r00" 703000" 01500" o*00'00"

@ The MWRA sewer system
serves more than 2 million
Massachusetts residents in
43 communities in eastern
Massachusetts. On the average
day, 370 million gallons of
sewage flows to one of two
MWRA sewage treatment facili-
ties located on the shores of
Boston Harbor. The MWRA is
currently in the middle of an
ambitious program to upgrade
and consolidate the sewage
treatment facilities serving
the region.

@ After nearly a decade of plan-
ning, design, and construction,
the MWRA started-up the new
Deer Island primary treatment
plant in January, 1995. The
primary treatment process
involves removing solids from
sewage and chlorinating effluent
prior to discharge. A new sec-
ondary treatment facility is cur-
rently under construction.
Secondary treatment combines
a bacterial process to decompose
sewage with a physical settling
process. Secondary sewage
treatment results in removal of
more than 75% of the organic
matter and toxic pollutants prior
to effluent discharge.

FIGURE 1-1

Distances of the new outfall
from selected sensitive areas
in Massachusetts and

Cape Cod Bays.

02 / OUTFALL MONITORING REPORT: 1994 - MWRA

@ Following treatment at the
MWRA's primary treatment
facilities, treated wastewater or
effluent flows into Boston
Harbor. The MWRA is currently
constructing a 9.5-mile long, 24-
foot diameter outfall tunnel.
This tunnel will discharge efflu-
ent from the new secondary
treatment facility to
Massachusetts Bay. Discharge
will occur through 55 diffusers
located at a depth of approxi-
mately 100 feet.

@ Water quality legislation in the
United States has a long history,
dating to 1899. The modern era
of water quality legislation
began in 1972 with the federal

Clean Water Act, that established

the National Pollutant Discharge
Elimination System (NPDES)
program. The NPDES program
requires all wastewater dis-
chargers, including the MWRA,
to obtain a NPDES permit.
Through the NPDES permit, reg-
ulatory agencies impose effluent

limitations on the amount of pol-

lutants discharged and other
requirements, Effluent limits
are based on state and federal
water quality criteria and stan-
dards which are designed to pro-
tect the water quality and aquat-
ic life in receiving water bodies.

During the preparation of the Secondary Treatment Facilities Plan, the Citizens Advisory
Committee identified the following general areas of concern with respect to Massachusetts
and Cape Cod Bays:

B Is it safe to eat fish and shellfish?

@ Are natural/living resources protected?
B Is it safe to swim?
@ Are the aesthetics being maintained?

An Outfall Monitoring Program was developed to meet agency requirements and address
citizens’ concerns.

1.3 Monitoring Program History/Status

Numerous scientific studies were carried out in 1986 and 1987 as part of the outfall siting
process. These studies and preliminary water column monitoring carried out in 1989 and
1990 formed a basis of information for monitoring plan development. At the direction of
the Massachusetts EOEA, an Outfall Monitoring Task Force (OMTF) was formed to provide
the MWRA with guidance and recommendations on the development of a monitoring plan.
The OMTF is composed of academic scientists, as well as representatives from federal and
state regulatory agencies and non-profit organizations.

MWRA and the OMTF initially developed an Outfall Monitoring Program in 1991. Baseline
studies, dedicated to determining background conditions in the Bays, began in 1992 (except
for flounder studies which began in 1991) and will continue until the new outfall becomes
operational in 1998. Then, similar post-discharge studies, dedicated to determining the
effects of the discharge, will begin.

The OMTF and MWRA review the monitoring results on an ongoing basis and work to
implement cost-effective modifications that better address public and technical concerns.

1.4 Monitoring Program Objectives

The Outfall Monitoring Program was developed and has evolved with continuous atten-
tion to a number of specific goals and objectives. The Outfall Monitoring Program is
intended to:

@ Develop baseline data from which future changes can be evaluated

@ Test whether the impact of the discharge is within the bounds
predicted in the SEIS;

Evaluate compliance with threshold values for trigger parameters
(as defined below); and

H Measure and evaluate potential impacts to Massachusetts and Cape Cod Bays
associated with outfall relocation.

Since 1992, baseline data have been collected to achieve the first objective. Additional data
are required to achieve this objective. The baseline data have demonstrated considerable
natural year-to-year variability in the water quality and biological characteristics of the Bay
system. These results indicate that the Massachusetts and Cape Cod Bay system is complex
and cannot be completely described with the information collected to date. Without a more

MWRA : OUTFALL MONITORING REPORT: 1994 / 08

complete understanding of the inherent behavior and natural variability of the Bay system
prior to the introduction of MWRA wastewater discharge, it may be difficult to determine if
wastewater has adversely affected water quality once the discharge into Massachusetts Bay
begins.

There have been several changes in both the system under study and in the monitoring
program during the past few years. Sludge disposal into the harbor was terminated in
December 1991, and the new primary treatment system became operational in 1995.
Ongoing monitoring is helping to assess the response of Boston Harbor and the bays to
these changes in pollutant discharges.

In addition to the outfall monitoring program, a related monitoring program for Boston
Harbor is currently being conducted by MWRA. This program assesses the water quality
and ecosystem recovery in Boston Harbor following treatment system improvements and
outfall relocation. ‘Together, the Outfall and Boston Harbor monitoring programs will pro-
vide information essential to evaluating the costs and benefits, as well as the potential
impacts of the treatment system and outfall modifications.

1.5 Wastewater Constituents of
Environmental Concern

The National Research Council has recommended consideration of the following six waste-
water constituents in determining the environmental impact of coastal discharges of treated
sewage:

@ Nutrients

Organic Material

B
& Toxic Contaminants
@ Pathogens

&

Solids
@  Floatables

The Outfall Monitoring Program was designed to obtain data that would allow an assess-
ment of the water quality and ecological impacts of these constituents. These six parame-
ters were evaluated within the context of four different environmental measurement areas,
or matrices: effluent, water column, benthic environment, and fish and shellfish.

The MWRA evaluates these program areas based on specific monitoring indicators, called
trigger parameters. Each trigger parameter has a quantitative, or in some cases a qualita-
tive, threshold that indicates the potential for impacts. Once discharge begins, the
exceedance of trigger parameter threshold values will automatically trigger MWRA action.
There are two types of thresholds under development that will be used to alert the MWRA
to different degrees of environmental risk. Warning levels indicate the potential for
increased risk of environmental impact, triggering an evaluation of potential impacts and
the need for more intensive study. Action levels trigger the need for a response to avoid an
environmental impact.

04/ OUTFALL MONITORING REPORT: 1994 : MWRA

1.6 Report Objectives and Organization

The objectives of this Outfall Monitoring Overview Report are to describe the monitoring
program goals, component elements, and results of the ongoing monitoring program. The
focus of this report is the Massachusetts and Cape Cod Bays system; pertinent information
on Boston Harbor has also been included.

A number of related reports have been produced by the MWRA. Although some of these
reports contain information similar to this overview, they provide substantially more
detailed information in specific areas. “The Effluent Outfall Monitoring Plan, Phase I:
Baseline Studies” (November 1991) and “Phase II: Post Discharge Monitoring” (draft
November 1995) describe the goals, strategy, and design of the Outfall Monitoring Program
in detail. The “Contingency Plan” (draft March 1995) provides a detailed discussion of the
development of trigger parameter values and MWRA's planned contingency measures. The
“State of Boston Harbor” reports focus on the Boston Harbor system, with less information
provided on Massachusetts and Cape Cod Bays.

The material presented in this report represents data collected through the 1994 field sea-
son, and therefore reflects the levels of sewage treatment current at that time. These data
are synthesized in a series of technical reports prepared annually for every project area
(more frequently for some). Synthesis reports for 1995 data are currently (Spring 1996) in
development and are expected to add to the understanding of the Harbor and Bay system.
A current listing of the technical reports can be found on the World Wide Web at
http://world.std.com/~enquad. Raw data from all studies are available in electronic form
through MWRA’s Environmental Management and Mapping system.

This report is organized into three primary areas: (1) this introduction that discusses the
reasons for and objectives of the monitoring program; (2) six sections that discuss each of
the wastewater constituents of concern, water quality and biological issues associated with
each constituent, monitoring program elements, and recent monitoring program results; and
(3) a summary of the Outfall Monitoring Program.

MWRA + OUTFALL TORING REPOR

2.0 NUTRIENTS

2.1 Water Quality/Biological Issues

Nutrients are essential for the growth of algae and other aquatic plants. Algae form the What are algae?
base of the aquatic food chain, and are critical to the maintenance of the aquatic ecosystem.
For marine and coastal environments, such as the Massachusetts and Cape Cod Bays sys- Se eee

tem, nitrogen is the most important nutrient. Sources of nutrient loading into the Bay sys- ‘nani o ete
tem include the MWRA discharge, discharges from several other municipal wastewater

treatment plants, Combined Sewer Overflow (CSO) inflows, nonpoint source rainfall runoff, vent hotbama. gee Pri
river and tributary discharges, and atmospheric deposition. As secondary treatment is el cre a encom dt
phased in, nutrient removal from the MWRA effluent will improve somewhat, and the rela- tions undergo periods of inter
tive nutrient contribution to the Bay system from the MWRA discharge will decrease. sie deni Connediieas,
The primary concerns associated with the discharge of nitrogen and other nutrients into the aa ee aa
coastal environment are related to effects on (1) dissolved oxygen (DO) concentrations and stacine fas Glau

(2) the algal community structure. :

2.1.1 Dissolved Oxygen Effects

Algal blooms are periods of intense algal growth that are often part of the natural aquatic

ecosystem. Excess nutrients, such as nitrogen, may lead to excessive algal blooms and

overabundant algal growth, a condition known as eutrophication. As algae die and decom-

pose, DO is consumed due to the oxidation of carbon in algal biomass. During eutrophica-

tion, DO consumption may lead to DO depletion and low DO concentrations. This condi-

tion, known as hypoxia, may have serious effects on fish and other marine animals which

need DO to breathe. The various processes that consume and otherwise influence DO con- FIGURE 2-1

centrations are shown and discussed on Figure 2-1. Dissolved oxygen processes

and reactions

8 For higher organisms, oxygen in the environment is a requisite

for life. Dissloved oxygen (DO) in marine waters is critical for the
ATMOSPHERE survival of fish and other aquatic life forms. An understanding of the
dynamics of DO in marine waters is essential to understanding the
distribution, growth. and behavior of aquatic organisms.

= DO saturation in marine waters is a function of several factors,
including temperature and salinity. Colder waters hold more DO
than warmer waters, Fresh water holds more oxygen than salt water.

= Water is said to be DO-saturated when it holds the maximum
possible amount of DO. For instance, water at 4°C can hold up to
13 mgIL DO betore it is considered saturated.

= Typically, cooler, well-mixed winter waters have the highest DO
concentrations, Stratification of water occurs in the summer months,
while mixed conditions predominate in winter months.

§ Atmospheric aeration and algal photosynthesis are two primary
sources of DO in marine waters.

= A combination of processes, including nitrification and respiration by
aquatic life, consume marine DO. Nitrification is the process
whereby ammonia is oxidized to nitrates and nitrites.

Death and decay of algal blooms result in reduced concentrations of
DO in water. If sufficient algae decay occurs, DO concentrations
may drop dangerously low and a condition known as hypoxia may
occur. Sensitive marine animals may suffocate during periods of
hypoxia.

ae GORGE ae aaa RT a TE = Considerable spatial variability exists relative to DO
wee ey : ES ie : we foals concentrations in Boston Harbor and Massachusetts Bay.
SEDIMENT > ss Sess eae . '| DO concentrations vary both vertically and horizontally, and marine
aa i on J : currents serve to transport DO in and out of marine habitats.
= : pares = Diffusive transport in sediments also occurs when DO moves from
areas of high to low DO concentrations.

NITROGEN CYCLE:

ATMOSPHERE 1B Nitrogen behavior in the aquatic environment is complex. In natural
water bodies, nitrogen can occur as dissolved nitrogen gas:
dissolved nitrate, nitrite, and ammonia species: and as part of
organic matter and aquatic organisms, The collective processes
involved with the behavior and transformation of nitrogen and its
species is known as the nitrogen cycle.

1B Nitrogen gas can enter and dissolve in the water column from the
atmosphere. This process is reversible.

& Dissolved nitrate, nitrite, and ammonia, collectively known as
dissolved inorganic nitrogen (DIN) are important nutrients for the
growth of aquatic plants, such as algae.

8 Nitrification is a process involving a reaction with dissolved oxygen
to change ammonia to nitrite and nitrite to nitrate.

8 Denitrification involves the reduction of nitrate to nitrite or dissolved
nitrogen gas, a process that occurs under anaerobic or oxygen
depleted conditions.

BB Nitrogen gas is generally not available to aquatic plants, but under
certain conditions blue green algae can use nitrogen gas
as a nutrient source of nitrogen in a process known as nitrogen
fixation.

I The decay of organic matter releases nitrogen species into the water
column, The decay of organic matter resulting in the release of
ammonia is called ammonification.

FIGURE 2-2
Nitrogen Cycle

Algae Communities

@ The composition of the algal
community, or the relative num-
bers of various algae species, is

known as the community assem-

blage. Approximately 30 to 50
algae species typically are
observed in the community
assemblage monitored by
MWRA. These include species
commonly known as diatoms,
blue-green algae, and flagellates.
(Figure 2-3). Flagellates are
planktonic algae that have limit-
ed self-propelled mobility. Red
tides are a specific kind of
dinoflagellate bloom that may
produce toxic chemicals. Some
red tides can result in mortality
of fish and other marine organ-
isms and toxicity of seafood.

In addition to potential eutrophication effects on DO, nitrogen can make a minor contribu-
tion to the loss of DO by reactions in which nitrogen species combine with and consume
DO. Nitrogen exists in a number of forms in the aquatic environment. The behavior and
interaction of the different forms of nitrogen in the environment is known as the nitrogen
cycle, and is described in Figure 2-2.

2.1.2 Algal Community Effects

Wastewater discharges to the marine environment can change the existing or natural nutri-
ent concentrations and concentration ratios in surface waters. In this changed environ-
ment, undesirable algae may grow faster than desirable algae. Undesirable algae include
nuisance algae, such as brown tides which affect the appearance of the water, and noxious
algae, such as red tides which are toxic to some organisms. In addition, there is a concern
that changes in the algal community could result in food chain impacts that affect endan-
gered species, such as humpback and right whales.

Numerous factors affect algae community composition and the potential for algal blooms.
These factors include a number of natural phenomena, such as nutrient availability, temper-
ature, light, time of year, salinity, and grazing by herbivores such as zooplankton.

2.2 Trigger Parameters and Thresholds

A number of trigger parameters have been established to evaluate the impacts of nutrients
on the Massachusetts and Cape Cod Bay system. These trigger parameters have been estab-
lished to monitor and measure nutrient concentrations in MWRA effluent and the bays,
eutrophication and hypoxia events, DO concentration in water and sediments, DO depletion
rate, algal biomass trends, and the growth of undesirable algae. A compilation of trigger
parameters and threshold values, with their bases, is provided in Table 2-1.

MWRA + OUTFALL MONITORING REPORT: 1994 / 07

Flagellated Unicellular Organisms Diatoms

Flagellated organisms are characterized by the presence of Diatoms are a group of algae characterized by cell walls
one or more long, whiplike structures called flagella which made of silica. Two major groups of diatoms are pennate
are used for locomotion. Flagellated organisms may be diatoms, which have bilateral symmetry, and centric
either naked with no cell wall or armored with a cell wall, diatoms which have radial symmetry.

such as some dinoflagellates with spiny cell walls.

colon .
¥, valve view

girdle view ,
Flagellate
Pennate
Diatom
Colony 4
10 um -—HI
25 um
Dinoflageliate

Diatom

————41
100 um

FIGURE 2-3
Typical Marine Algae
Source: Linneaus Protist™ and Linneaus Toolkit™

08 / OUTFALL MONITORING OVERVIEW REPORT: 1994 : MWRA

Trigger Parameter

TABLE 2-1

Threshold Values

Trigger Parameters and Threshold Values for Nutrients

Basis for Trigger Parameter
and Threshold Values

Nitrogen Effluent Loading

Warning Level:

— Annual effluent nitrogen load more than 12,500 metric tons.
Action Level:

~ Annual Effluent nitrogen load more than 14,000 metric tons.

Measures mass of nitrogen discharged
Thresholds based on effluent

nitrogen loads used in water

quality modeling and SEIS

- Nearfield annual mean bottom DO concentration below baseline
by more than one standard deviation for 3 consecutive years.

Water Column DO Warning Level: , .
Concentration ~ Monthly mean nearfield bottom DO less than 6.5 ppm Measures potential for hypoxia,
(or 80% of saturation) during the summer (June-October). or low DO impacts
- Monthly mean Stellwagen Basin bottom DO less than 6.5 ppm Action levels based on
(or 80% of saturation) during the summer. Vite Quatty San dards
Action Levels:
- Monthly mean nearfield bottom DO less than 6 ppm
(or 75% of saturation) during the summer.
- Monthly mean Stellwagen Basin bottom DO less than 6 ppm
(or 75% of saturation) during the summer.
Water Column DO Trends Warning Levels:

Measures long-term trends

in DO levels

Warning levels based on water
quality modeling prediction of
DO changes due to effluent
discharge

DO Depletion Rate

Warning Levels:

~ Nearfield mean bottom oxygen depletion rate greater than 2 times
the baseline rate during summer.

~ Steliwagen Basin mean bottom summertime oxygen depletion rate
greater than 2 times the baseline rate.

- Measures short-term and long-term rate

of DO depletion and potential for future
hypoxia

Thresholds based on prediction in SEIS
that might indicate the potential for
hypoxia.

DO Concentration and
Depth in Sediments

Warning Level:

— Decrease in baseline mean redox potential discontinuity (RPD) depth
at muddy nearfield stations by 50%.

- Decrease in mean RPD depth by 20% per year for 3 consecutive years.

Measures potential for low DO
impacts on animals that live in
bottom sediments

Thresholds based on evaluation
of DO penetration into sediments

MWRA : OUTFALL MONITORING REPORT: 1994 / 09

TABLE 2-1 (cont'd)
Trigger Parameters and Threshold Values for Nutrients

Basis for Trigger Parameter
and Threshold Values

Trigger Parameter Threshold Values

Chlorophyll-a Concentration Warning Levels:

- Chlorophyll-a concentration annual mean nearfield or farfield
variability greater than 2 times the baseline level,
for 3 consecutive years.

~ Increase by factor of two relative to baseline level in
annual mean neartield or farfield chlorophyll-a concentration,
for 3 consecutive years.

— Annual mean neartield or farfield chlorophyll-a concentration
greater than 12 ppb.

- Increase in annual mean nearfield chlorophyll-a concentration
by 20% per year for 3 years.

- Change in seasonal nearfield or fartield chlorophyll-a, or
nearfield or farfield euphotic zone chlorophyll-a pattern.

Action Level:

~ Annual mean nearfield or fartield chlorophyll-a concentration
greater than 15 ppb.

— Measures algal biomass and provides
indication of eutrophication state.

— Thresholds based on long-term
statistical increases in algal biomass and
National Oceanic and Atmospheric
Administration (NOAA) recommended
level for indication of excessive algal bloom
activity.

Nuisance/Noxious Warning Levels:

Algae Concentration - Nuisance or noxious algae concentration in nearfield or farfield
greater than 10 times baseline conditions for 3 years.

- Nuisance or algae frequency of occurrence in nearfield or fartield
greater than baseline conditions.

- Nuisance algae dominate the nearfield or farfield
algal community.

— Measures and evaluates increases
in undesirable algae concentrations
and associated environmental impacts.

~ Warning levels based on predictions in
SEIS that discharge will not increase
undesirable algae concentrations.
Action levels based on qualitative indications
of undesirable algae impacts.

2.8 Monitoring Program Components Chlorophyll is the green pigment

Designed to Address Issues in plants that supports photo-

synthesis. Chlorophyll is used

MWRA has conducted extensive water quality modeling studies to evaluate the potential as a measure of the algal bio-
effects of outfall relocation. The results of the modeling studies indicate that outfall relo- mass, the total amount of algae
cation will significantly reduce nutrient and chlorophyll concentrations, while increasing in the water. The type of chloro-
DO concentrations, in Boston Harbor. The study results also show that detectable phyll most commonly measured
changes in nutrient levels, chlorophyll, or DO will not occur in Massachusetts or Cape is chlorophyll-a.

Cod Bay, except in the immediate vicinity of the new outfall. The modeling study was
used to assist in the design of the water column monitoring program, which will be used
to verify the modeling study results.

To establish baseline conditions in the bays, the MWRA is monitoring nutrients through a
number of different analytical techniques. Some analyses focus on measurement of concen-
tration of nutrients in MWRA effluent, while other studies evaluate ongoing nutrient and
other water quality trends in the receiving waters. Nutrient sampling is occurring at sta-
tions in the nearfield (within about 5 km of the site of the future outfall) and in the farfield

10 / OUTFALL MONITORING REPORT: 1994 - MWRA

f@ MWRA will perform statistical
tests to determine if significant

changes in the environment a
have occurred as a result of the
effluent discharge. The tests will 5

employ common statistical meth-
ods and have a 20% chance of
identifying no change when
there has been a change and a
5% chance of identifying a
change when there has not been
a change. a

demand.

(throughout Massachusetts and Cape Cod Bays) (Figure 2-4). Monitoring program compo-
nents associated with nutrients are as follows.

The total nitrogen concentration and load are directly monitored in MWRA efflu-
ent, prior to discharge to the bays.

Dissolved oxygen (DO) and nutrients are routinely monitored at numerous stations
in the nearfield and farfield. Analysis of long-term DO monitoring data allows the
MWRA to track trends in DO conditions, and anticipate future hypoxic conditions,

@ = The depth of oxygen penetration in soft sediments is monitored to provide a mea-
sure of environmental health with respect to sediment oxygen supply and

In order to monitor long-term changes in algal biomass, chlorophyll-a concentra-

tions are monitored in the nearfield and farfield.

™ Nuisance or noxious algae are annually present in small numbers in
Massachusetts and Cape Cod Bays. To evaluate changes in the frequency or abun-
dance of these organisms, ongoing monitoring of nuisance and noxious algae pop-
ulations is underway.

2.4

Monitoring Program Results

Moving the location where effluent is discharged to the marine environment has the poten-
tial to change the relative levels of nutrients in water. MWRA has conducted a comprehen-
sive nutrient sampling program in Massachusetts and Cape Cod Bays since 1992. In addi-

tion to monitoring nutrients directly, the monitoring program also measures parameters that

FIGURE 2-4
Nearfield and Farfield water
column sampling locations

i
# Nearield Water:
Column Locations |

| @ Fartiels Water
Column Locations

7000"

To"so0" 70"30'00" o"1s00" ‘7r00'00"

ee een enn Ber

aris"

~-} azropo0*

nutrients could impact (e.g., algae populations, DO concentrations). This monitoring pro-
gram provides MWRA scientists with sound baseline water quality data.

Effluent

In the 1994 sampling program, total nitrogen (the sum of
particulate and total dissolved nitrogen) in the primary
effluent samples ranged from 740 to 1,740 uM (10.4 to
24.4 ppm) (Figure 2-5). The 1994 annual load of total
nitrogen was estimated at 8,220 metric tons. This value is
well below the annual nitrogen loading threshold warning
level of 12,500 metric tons (the action level is 14,000 met-
ric tons). Seventy to ninety percent of the nitrogen in the
effluent was present as ammonia. Significant seasonal
variability was observed in total nitrogen levels. This is
not unusual, given the variability in daily flows into and
out of the treatment facility. Average winter and spring
(December-May) concentrations of total nitrogen were con-
siderably lower than the average concentrations observed
in the summer and fall. This trend corresponds inversely
with, and may reflect, the effluent flow conditions during
the sampling period. Lower flows occurred in summer
months, while flows tended to be higher in the winter and
spring.

MWRA - OUTFALL MONITORING REPORT: 1994/11

Water Column Nitrogen

Monitoring dissolved inorganic nitrogen (DIN) in the water column provides a measure of
the effects associated with nitrogen loading to the Massachusetts Bay and Cape Cod Bay
systems. MWRA began monitoring of DIN in Massachusetts Bay and Cape Cod Bay waters
in 1992. The DIN measurements from 1994 indicated similar patterns to those in previous
years. Spatially, DIN concentrations are generally highest in Boston Harbor and decrease
with increasing distance offshore (Figure 2-6). Annually, the highest DIN values in
Massachusetts Bay surface waters occur before April and after October. Surface DIN con-
centrations generally decrease as nitrogen is consumed by algal growth during the spring,
summer, and early fall.

Water Column Chlorophyll

Spatial and temporal patterns of chloro-
phyll concentration are related to those of
DIN. The average chlorophyll concentra-
tions in Massachusetts Bay surface waters 1500
in 1994 were generally higher in the
nearshore coastal region with decreasing

aan 20
a Lis
values offshore. The highest chlorophyll

1000 LS

measurements were located along the ™~ [_—— = pte
shore to the southeast of Boston Harbor. 500

The seasonal trends for chlorophyll in + 5
nearshore and offshore Massachusetts Bay
in 1994 included: (1) relatively low con- 0 Jeo's3 a Tiny 0 + Tay'3a +—~Sahea +0
centrations in the winter, (2) a rapid Jan '94 Apr '94 Jun "94 Aug "94 Nov '94
increase in the spring associated with a Month Sampled

springtime algal bloom, (3) generally - Total Nitrogen fe Ammonia ~* Particulate Organic N |
increasing values during the summer, and

(4) peak concentrations in October associ- FIGURE 2-5

ated with a fall algal bloom. These trends are similar to those seen during the 1992 and Nitrogen. ammonia, and partic
1903 measurement periods ulate organic nitrogen in Deer
P : Island effluent. Symbol repre-

sents mean concentration, hori-
Chlorophyll in Cape Cod Bay followed a significantly different seasonal pattern than in zontal lines show concentration

Massachusetts Bay. In Cape Cod Bay, very high chiorophyil measurements, higher than any range. Source: Hunt et al., 1995
of the peak measurements in Massachusetts Bay, were obtained during late winter-early

spring. Low chlorophyll values were measured during the late spring and summer, fol-

lowed by a relatively low peak in the fall. This indicates that the Massachusetts Bay and

Cape Cod Bay ecological systems behave somewhat independently, at least with respect to

chlorophyll.

2000

Concentration, uM
Concentration (ppm)

Chlorophyll concentrations in the water column provide a valid measure of algal blooms
and eutrophication. Concentrations of chlorophyll in Massachusetts Bay are generally low.
Average nearfield chlorophyll levels for the period 1992-1994 were relatively consistent in
the Bay systems (2.0, 2.4, and 2.0 ppb, respectively). Figure 2-7 shows surface layer
chlorophyll concentrations (depth averaged 0-20m) in the nearfield portions of the system
in 1992, 1993, and 1994. A comparison of these results with the chlorophyll threshold val-
ues indicates that current levels of chlorophyll at the nearfield stations are less than either

1994 - MWRA

the warning or action levels (12 and 15 ppb,
respectively). These results indicate that,
under current conditions, algal biomass in
the nearfield does not present a major water
quality problem.

Overall, the monitoring results demonstrate
that the monitoring program is sensitive
enough to measure spatial gradients and
seasonal variability. This provides a high
degree of confidence that the program will
be adequate to detect any changes in algal
concentrations that might result from outfall
relocation.

71°00'00" 70°45"00"

FIGURE 2-6

Spatial pattern of annual mean
surface DIN concentration (uM)

za

in Massachusetts Bay in 1994.
(Kelly and Turner, 1995)

FIGURE 2-7

Surface (0-20 meters) chlorophyll
concentrations in the nearfield.
(Bars represent 2 standard errors

on the mean of data.)

Chlorophyll (ppb)

Dissolved Oxygen

DO concentrations in marine waters vary
according to season and location. (Figure 2-
1 summarizes the many processes that affect
DO concentrations.) Thermal stratification
of the water column is one of the most sig-
nificant factors influencing seasonal DO vari-
ability in the Massachusetts and Cape Cod
Bay system. From late fall through early spring, the water column is well mixed with little
vertical variation in temperature, DO or other water quality parameters. Thermal stratifica-
tion of the water column in the Bays occurs during the summer as surface heating causes
surface waters to become warmer than bottom waters. Because warm water is lighter, or
less dense, than cold water, the warm surface water and cold bottom water tend to form
separate, stratified layers. Because of DO production from algal activity and atmospheric
reaeration, DO levels in the surface layer are generally high. In contrast, DO in the bottom
layer typically declines due to DO consumption from respiration and decay of organic mat-
ter, and the lack of atmospheric reaeration.

70°30'00"

70°00'00"

15 -—|Action Level = 15

Comprehensive DO and temperature data
have been collected in Massachusetts and

Warning Level = 12

Cape Cod Bays since 1992. Figure 2-8
shows surface and bottom layer tempera-
ture measurements throughout the year
for 1992 - 1994. Surface and bottom mea
surements are indistinguishable from late
fall through early spring, indicating well-
mixed conditions. Starting in the early
spring each year, the surface layer temper-
ature increases much more rapidly than
the bottom layer temperature resulting in
stratified conditions by late spring. In

1994, the stratification began earlier and
bottom layer temperatures in the summer

MWRA + OUTFALL MONITORING REPORT: 1994 / 13

and fall were higher than in previous 25
years. Figure 2-9 shows a compari-

son of bottom water DO concentra-

tions in the nearfield of the future 20
outfall site between 1992-1994.

Mooring surface , and bottom temperature.
Ship survey surface 4 , andbottom ¥_ temperature.

Nearfield bottom water DO concen- > 15 A
trations declined after the early sum- 3 A
mer months in all three years 5

because of stratification and the = 10

other processes described above. ©

Early spring DO concentrations were

Jower and the DO decline began ear- 5
lier in 1994 than in previous years.

By October 1994, the DO concentra-

pe

Fe OS OO

i indivi DPT TTT Et
Se eee won JFMAMJJASOND JFMAMJJASONDJFMAMJJASOND
samples were below the 6.0 ppm
action level for nearfield locations. 1992 1993 1994
The lowest DO concentration Troe et » lover
observed in October 1994 was 4.8 ppm, substantially below the 1993 minimum concentra- uriace and Poltom faye!

. , oo age temperatures in the outfall
tion. The low 1994 DO concentrations may be a result of low initial DO values, the early nearfield.

onset of stratification, and high bottom water temperatures in summer and fall. The high
water temperatures would have caused higher DO consumption due to higher respiration

and organic material decay rates, and a lower capacity to hold oxygen. FIGURE 2-9
Concentrations in outfall near

Sediment field (bars represent two
standard errors on the mean

A number of processes, including res- of data).

piration of bottom dwelling organ- 13

isms and decay of organic material in

sediments, act to consume and ~ 134

reduce oxygen levels in sediments. &

As a result, sediments generally 2" tom

undergo a transition with depth from 5 40-4 a

oxygenated (aerobic) to anaerobic S +

(having no oxygen). The redox oO 9 4

potential discontinuity (RPD) depth 9

is the depth at which this transition 3 FT

occurs. The RPD is dependent on 3 74

several factors, including inputs of 4 Warning Level 6.5

organic carbon and water tempera- 6 Action level 6

ture. Measurement of sediment RPD

provides a sensitive indicator of "TTA | JASONG JEAN J IASONDJENAMIIASOND

change in sediment; more deeply

oxygenated sediment supports a high- 1992 1993 1994

er quality benthic community, whereas less oxygenated sediment often supports only a
degraded community.

The average RPDs in nearfield and farfield sediments during the August baseline study are
relatively consistent (Figure 2-10). RPDs were generally 5 to 7 cm, and were lowest in the

14/ OUTFALL MONITORING REPORT: 1994 - MWRA

10

RPD (cm)

1993

Year

FIGURE 2-10

Measured RPD (redox potential
discontinuity depth) in
Massachusetts Bay sediments.
(lines represent one standard
deviation.)

organic-rich sediments of Boston Harbor. It is
anticipated that, as effluent water quality

EB Farfield improves, the Boston Harbor RPDs will

HB Boston Harbor] —_increase. An advantage of measuring sedi-
ment RPD is that this parameter responds
rapidly to changes in organic matter loading.
Continued observation of sediment RPDs in
Massachusetts and Cape Cod Bays will allow
the MWRA to evaluate benthic impacts associ-
ated with the new secondary treatment plant
and outfall tunnel.

1994 Nuisance and Noxious Algae

The MWRA monitors a number of species of
nuisance and noxious algae in Boston Harbor and the bays. To date, the MWRA monitor-
ing program has shown that undesirable algae are present at acceptably low levels within
the Massachusetts and Cape Cod Bay system. A separate study of toxic red tides (D.
Anderson, pers. comm.) concluded that these algae most often occur in shallow embay-
ments to the north of Massachusetts Bay, and that wind and rainfall play a significant role
in red tide blooms. The algae were less influenced by nutrient loading because they are
able to swim down to deeper nutrient-rich water.

3.0 Organic Material

3.1 Water Quality Issues

Organic material occurs naturally in water bodies and may also be introduced by waste-
water effluents. The decay or decomposition of organic material in waterbodies consumes
DO and in excessive amounts may contribute to DO depletion and hypoxia. Figure 2-1
describes the interaction between DO and organic material, as well as the other processes
that control DO concentrations.

The amount of DO consumed by decomposing material in effluent is the biochemical oxy-
gen demand (BOD) which consists of the nitrogenous biochemical demand (nBOD) and the
carbonaceous biochemical oxygen demand (cBOD). The best parameter to provide a mea-
sure of the DO consumption by organic material is the cBOD. This is because the exertion
of nBOD, caused by ammonia oxidation, is a much slower process in the environment.
Oxidation of ammonia can be significant when ammonia levels are relatively high, as is the
case in effluent and nearfield receiving waters.

3.2 Trigger Parameters and Thresholds

Many of the environmental measurement parameters (for example, bottom water DO, sedi-
ment RPD) that might be associated with organic material can also be related to nutrient
levels. The cBOD concentration in the wastewater effluent is the trigger parameter for
organic material. Threshold values specific for organic material were developed based on
anticipated NPDES permit values. These values are shown on Table 3-1.

In addition, the DO and sediment trigger parameters and thresholds discussed in the nutri-
ents section above also apply to organic material.

3.8 Monitoring Program Components Designed
to Address Issues

In addition to the water quality and nutrient monitoring programs, the MWRA evaluates
the cBOD in the wastewater effluent on a daily basis. The effluent cBOD is monitored to

TABLE 3-1
Trigger Parameters and Threshold Values for Organic Material

Basis for Trigger Parameter
and Threshold Value

Trigger Parameter Threshold Value

cBOD Concentration in Effluent

Warning Levels:
— Weekly mean cBOD greater than 36 ppm.

~ Monthly mean cBOD greater than 22.5 ppm.

~ Provides measure of organic loading to bay.

~ Warning levels based on 90% of expected
NPDES permit limits.

— Action levels based on expected NPDES
permit limits.

Action Levels:
— Weekly mean cBOD greater than 40 ppm.
— Monthly mean cBODF greater than 25 ppm.

16 / OUTFALL MONITORING OVERVIEW REPORT: 1994 - MWRA

ensure that treatment is adequately removing organic matter. In addition to effluent moni-
toring, potential impacts from organic matter on receiving waters are also evaluated through
evaluation of levels of particulate organic carbon in the water column.

$8.4 Monitoring Program Results

In 1994, monthly cBOD levels in Deer Island effluent ranged from 90 to 140 ppm; seasonal-
ly, cBOD tended to be lower in the spring and highest in the summer months. The cBOD in
Deer Island effluent averaged approximately 100 ppm during 1994. This value was above
the established warning and action thresholds (22.5-40 ppm). This is to be expected, as
much of the organic matter in MWRA's system is dissolved, and not efficiently removed by
primary treatment.

In January 1995, MWRA began the startup period of the new primary treatment plant on
Deer Island. Although total suspended solids (TSS) concentrations in effluent appeared
slightly lower than in 1994, the preliminary data suggest that the cBOD concentrations did
not significantly drop. The MWRA anticipates that full completion of the new primary and
secondary treatment facilities will improve the effluent quality, and that TSS and cBOD lev-
els will drop substantially once these plants are on-line. Expected cBOD values from the
primary treatment system are in the range of 80-100 ppm. After startup of the secondary
treatment system, it is anticipated that cBOD levels will drop to 10-15 ppm.

4.0 Toxic Contaminants

4.1 Water Quality Issues

Toxic contaminants can cause direct harmful effects to organisms from short-term exposure
and/or can cause disease, such as cancer, from long-term exposure. Toxic contaminants
include heavy metals (such as lead, mercury, chromium, and cadmium); volatile organic
compounds (such as benzene, toluene, and chlorinated solvents); semi-volatile organic
compounds (including polychlorinated biphenyls [PCBs], polyaromatic hydrocarbons
{PAHs], and pesticides such as DDT); ammonia; and chlorine. Many toxic contaminants of
concern, particularly heavy metals and semi-volatile compounds, tend to preferentially
adhere or partition to suspended particulate matter in the water column and settle out onto
the seafloor.

Because many toxic contaminants adhere to particles, toxic impacts on marine animals are
likely to primarily affect bottom-dwelling organisms and the animals that feed on them,
such as flounder and lobster. Shellfish, such as mussels and clams, that feed by filtering
suspended matter from large quantities of water are also potentially vulnerable to toxic con-
taminants. Exposure of flounder to toxic contaminants may result in fin rot, liver tumors,
and other diseases. Consumption of contaminated organisms results in exposure of preda-
tors through the food chain. Human exposure to toxic contaminants in sea water may be
direct, from swimming or wading, or through consumption of contaminated fish and shell-
fish.

4.2 Trigger Parameters and Thresholds

Trigger parameters and thresholds for toxic contaminants have been established to identify
potential toxic problems by measuring and evaluating toxic loading in the discharge efflu-
ent, the dilution achieved by the diffuser, toxic contaminant concentrations in water and
sediments, and toxic concentrations in and effects on marine life. Specific trigger parame-
ters and thresholds are provided in Table 4-1.

4.8 Monitoring Program Components Designed Hi Effluent bioassay testing is used

to Address Is sues to measure the potential toxicity
of wastewater to aquatic organ-

The MWRA is monitoring potentially toxic contaminants through the use of a number of isms. Aquatic toxicity measure-
different studies. ment parameters include the No
Contaminant concentrations of numerous chemicals are directly monitored in Observed Bffect Concentration
effluent prior to discharge to the bays. (NOBC) and LC50, or effluent
Hi Bioassay tests, which measure the response of indicator species to treated effluent, concentration that is lethal to
are being used to evaluate toxicity to various life stages of marine organisms, such 50% of the test organisms.

as shrimp, finfish, and sea urchins.

Sediment in the vicinity of the outfall and throughout the bays is monitored for
toxic contaminants. A bacterium, Clostridium perfringens, is also measured in
sediments, providing a sensitive indicator of sewage discharge effects on bottom
sediments.

18 / OUTFALL MONITORING OVERVIEW REPORT: 1994 - MWRA

Trigger Parameter

Effluent Toxic
Parameter Analysis

TABLE 4-1

Trigger Parameters and Threshold Values for Toxic Contaminants

Threshold Values

Warning Level:
~ Toxic contaminant concentrations and effluent toxicity greater than 90%
of the expected NPDES permit limits.
Action Levels:
- Effluent LC50 less than 50% for shrimp (Mysidopsis bahia).
~ Effluent NOEC for fish (Menidia beryllina) growth less than effluent con-
centration at the edge of the mixing zone.
- Effluent NOEC for sea urchin (Arbacia punctulata) fertilization less than
effluent concentration at the edge of the mixing zone.
- Toxic contaminant concentrations and effluent toxicity greater than limits
set by the expected NPDES permit.

Basis for Trigger

Parameter
and Threshold Values

- Measures discharge of toxic
parameters.

- Thresholds based on expected
NPDES permit limits.

Diffuser Dilution

Warning Level:
— Effluent dilution less than predicted in the expected NPDES permit.

— Measures dilution achieved by
diffuser compared to dilution
needed to protect the nearfield
from toxic impacts.

~ Thresholds based on expected
NPDES permit limits.

and caged mussel edible tissue by a factor of two, for 3 consecutive
years.

- Annual mean PCB concentration in flounder, lobster, and caged mussel
edible tissue greater than 1 ppm wet weight.

- Annual mean lead concentration in caged mussel edible tissue greater
than 2 ppm wet weight.

~ Increase in annual mean lead concentration in caged mussel edible tis-
sue by 20% per year relative to baseline conditions, for 3 consecutive
years.

- Centrotubular hydropic vacuolation prevalence in flounder liver at future
outfall site equal to average baseline prevalence in Harbor flounder.

Action Levels:

~ Annual mean mercury concentration in flounder, lobster, and caged mus-
sel edible tissue greater than 0.8 ppm wet weight.

- Annual mean PCB concentration in flounder, lobster, and caged mussel
edible tissue greater than 1.6 ppm wet weight.

- Annual mean lead concentration in caged mussel edible tissue greater
than 3 ppm wet weight.

Sediment Toxic Warning Level: ~ Measures potential for toxic
Concentrations — Toxic contaminant concentration in sediment at mid-field (2-7 km from effects on benthic marine life in
outfall) stations greater than 90% of the EPA sediment criteria or NOAA sediments.
ER-M values. — Thresholds based on national
Action Level: sediment quality criteria.
- Toxic contaminant concentrations in nearfield sediment greater than EPA
sediment criteria.
Warning Levels: ~ Measures contaminant body
Toxic Accumulation - Annual mean mercury concentration in flounder, lobster, and caged mus- burden and incidence of dis-
and Effects on sel edible tissue greater than 0.5 ppm wet weight. ease in marine organisms to
Marine Life — Increase in annual mean contaminant concentration in flounder, lobster, evaluate contaminant exposure

and identify unanticipated
effects on marine life.

— Thresholds are based on U.S.
Food and Drug Administration
Action Levels.

MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1994 / 19

H Tissue analyses, which measure concentrations of toxic chemicals in animal tissue,
are being used to evaluate bioaccumulation of certain contaminants in flounder,
lobster, and mussels.

Abnormalities, such as diseased livers and fin rot in flounder and diseased gills in
lobster, are being monitored to evaluate adverse effects associated with exposure
to contaminants.

4.4 Monitoring Program Results

Exposure to toxic contaminants in sewage may result in risks to human health and the
environment. Humans may be exposed to contaminants through ingestion of accumulated
contaminants in seafood. Marine organisms such as finfish and shellfish may be harmed
by chronic exposure to toxic contaminants. Filter feeders such as mussels, and bottom
feeders such as flounder, are particularly at risk from exposure to toxic contaminants in the
bays. When humans or other predators eat fish and shellfish that have accumulated toxic
contaminants, exposure to these chemicals may occur through the food chain.

4.4.1 Effluent

To evaluate levels of trace metals and organic contaminants in the effluent, the MWRA col-
lects and analyzes samples from the effluent wastestream at the Deer Island plant. Bi-
monthly twenty-four hour composite samples are collected two days apart. The effluent
monitoring program uses clean sampling and laboratory analysis methods in order to detect
very low levels of contaminants. This is necessary because toxic contaminant levels in
MWRA effluent are so low that normal NPDES methods, developed by the EPA, would not
be able to detect or quantify effluent contaminants. These low detection methods provide a
sensitive measure of the toxic pollutant loading associated with the MWRA discharge. In
addition, Clostridium perfringens, which is measured in both effluent and sediments, forms
stable spores which provide a tracer of sewage solids in Boston Harbor and the bays.

In general, monitoring data indicates significant reductions in toxic contaminant levels over
the past few years due in part to the efforts of MWRA’s Toxic Reduction and Control
(TRAC) Department to reduce the amount of toxic pollutants discharged into the MWRA
system. The 1994 results were obtained before start up of the new primary treatment sys-
tem. Initial data since then indicates that the new primary treatment system is resulting in
a small further reduction of toxics in effluent. Effluent quality is expected to improve fur-
ther as the reduction in toxic discharges to the system continues, as the primary treatment
process continues to improve, and as secondary treatment is phased in.

Average effluent analyte concentrations for the Deer Island Treatment Plant from June 1993
to November 1994 are presented in Table 4-2 (organics) and Table 4-3 (inorganics). These
tables also include acute and chronic marine water quality criteria, and expected concentra-
tions within the nearfield mixing zone of the new diffuser. (It should be noted that those
concentrations conservatively assume no reduction in toxics in effluent before outfall reloca-
tion). None of the mean concentrations of organic analytes exceed acute water quality cri-
teria. Average concentrations of three pesticides (4.4-DDT, dieldrin, and endrin) in the
undiluted effluent were, however, higher than chronic criteria. With respect to metals,
undiluted effluent silver, mercury, lead, and zinc levels exceeded chronic criteria for the pro-

& Water quality criteria are maxi-

mum pollutant concentration
values, or minimum concentra-
tions of desirable parameters
(such as DO), that were estab-
lished to support a specific
water body use, such as protec-
tion of aquatic life. Acute crite-
ria values were developed to be
protective of relatively short-
term (less than 96 hours) expo-
sure to pollutants. Chronic cri-
teria are values that provide pro-
tection from relatively long-term
pollutant exposure.

Wi Effluent sampling provides the

MWRA with the ability to moni-
tor several nutrients, trace
metals, and anthropogenic
organic compounds prior to
discharge. As the level of
treatment increases, effluent
quality is expected to improve
substantially.

20 / OUTFALL MONITORING OVERVIEW REPORT: 1994 - MWRA

tection of aquatic life, while copper and silver concentrations exceeded acute criteria.
However, nearfield dilution predictions (assuming a 100:1 initial dilution) indicate that
organic and metal concentrations in Massachusetts Bay (shown in Tables 4-2 and 4-3)
would meet acute and chronic criteria values within a few meters of the new outfall dif-
fuser.

The potential for secondary treatment to improve effluent water quality was evaluated
through a pilot treatment plant study. Relatively little pilot treatment plant data are current-

TABLE 4-2

Organic Contaminant Concentrations (ppb) in Undiluted Effluent and
in Future Outfall Mixing Zone Compared to EPA Aquatic Life Criteria

Marine Acute | Marine Chronic Mean Predicted
Water Quality Water Quality Mean Effluent Concentration
Parameter Criteria Criteria Concentration’ | in Mixing Zone’

Pesticides
Aldrin 13 NC 0007 0.000007
4, 4-DDT 0.130 0.001 .0099 0.0001
Dieldrin 0.710 0.0019 0024 0.00002
Endrin 0.037 0.0023 0026 0.0003
Heptachlor 0.053 0.0036 .0007 0.000007
Heptachlor

Epoxide 0.053 0.0036 0013 0.00001
Lindane 0.160 NC 014 0.0001
PAH
Acenaphthene 0.970° 0.710° 0.163 0.0016
Fluoranthene 40° 16° 0.194 0.0019
Naphthalene 2,350° NC 1.350 0.0135
PAH 300° NC 20.761 0.207

‘Average concentration in samples in which contaminant was detected.

2Estimate based on discharge mixing zone dilution of 100:1.

5 Value presented is a lowest observed adverse effects concentration (LOAEC); insufficient data are available for
EPA to develop aquatic life criteria. NC = No established criterion.

Source: Hunt et al., 1995

TABLE 4-3

Mean Concentration (ppb) of Metals in Undiluted Effluent and in
Future Outfall Mixing Zone Compared to EPA Aquatic Life Criteria

Marine Acute | Marine Chronic Mean
Water Quality Water Quality Mean Effluent Concentration
Parameter Criteria Criteria Concentration | in Mixing Zone’
Silver
Cadmium

Chromium (Ul)
Copper
Mercury
Nickel

Lead
Zinc

1 Conservative estimate based on 100:1 dilution of effluent with seawater containing the maximum Massachusetts Bay
concentration in Table 4-4.

? Proposed criterion. NC = No established criterion. NA = Not analyzed.

Source: Hunt et al., 1995.

MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1994 / 21

TABLE 4-4

Comparison of Metal Concentrations (ppb) in the Pilot Treatment Plant Effluent,
Deer Island Effluent, Ambient Values in Massachusetts Bay, and EPA
Chronic Water Quality Criteria

Pilot Plant Effluent
Concentration?

' Ambient water EPA Chronic

1994 Effluent Concentrations in Water Quality
Parameter Concentration Primary Secondary Massachusetts Bay’ Criteria
Silver 49 3 0.6 NA 0,924
Cadmium 07 5 0.03 0.02 - 0.03 9.3
Chromium 40 7 27 0.10 - 0.18 50
Copper 74.7 §7 8 0.1-0.3 2.94
Mercury 0.15 0.1 0.02 0.0005 - 0.003 0.025
Nickel 6.3 9 5 0.26 - 1.6 8.3
Lead 11.8 20 14 0.03 - 0.2 85
Zinc

87.00 88 30 0.08 - 0.6 86

‘Average value from June 1993 through November 1994.

2Pilot plant results are generally the highest concentrations measured in tests conducted in July 1994.

3Massachusetts Bay data concentrations near future outfall site. NA = Not analyzed.

Proposed criterion.

Source: Hunt et al., 1995.

ly available, and the results must be considered preliminary. However, as shown in Table 4-
4, with the exception of copper, metals concentrations in undiluted effluent from the pilot
treatment plant study were well below any federal water quality criteria. When one consid-
ers the expected 100-fold effluent dilution within meters of the outfall diffuser, it appears
doubtful that any exceedances of toxic parameter water quality thresholds will occur once
the future outfall and secondary treatment system are both operating.

4.4.2 Sediment

Toxic contaminants, including metals and semi-volatile organics such as PCBs and 4,41-
DDT, tend to concentrate in bottom sediments. Sediment contaminant testing is necessary
to verify model predictions of toxic contaminant buildup in sediments in the nearfield
region of the future outfall site. These conservative calculations, which are intentionally
designed to overpredict possible contaminant build-up, indicate that after outfall relocation
it will take years before measurable increases of toxics in sediments could possibly be
reached and decades before levels could potentially reach those that might cause biological
effects.

The MWRA has conducted annual sediment sampling since 1992 at 20 locations in the
nearfield, and at 11 stations throughout the remainder of Massachusetts and Cape Cod Bays.
Analytical parameters include metals, PCBs, PAHs, pesticides, total organic carbon, grain
size, and sewage tracers. In general, contaminant levels in nearfield sediments and in the
bays have been considerably below draft criteria established by EPA for several PAHs and
pesticides. Concentrations of these parameters in the bays are typically less than in Boston
Harbor sediments. Representative concentrations of metals evaluated in 1994 are shown in
Table 4-5. Contaminant concentrations can be generally characterized as low, with substan-
tial variability between sampling stations. Concentrations of a few contaminants exceed the

Sediment Quality
Guidelines

@ Sediment quality guidelines are

useful screening tools to evalu-
ate potential impacts to sedi-
ment-dwelling organisms. The
National Oceanographic and
Atmospheric Administration
(NOAA) has developed effects-
based guidelines based on a
weight of evidence from many
studies. Chemical concentrations
below the NOAA “Effects Range-
Low” (ER-L) values are rarely
associated with toxic effects,
whereas chemical concentra
tions above the NOAA “Effects
Range Median” (ER-M) values
often are associated with toxic
effects.

22 / OUTFALL MONITORING OVERVIEW REPORT: 1994 : MWRA

TABLE 4-5

Comparison of 1994 Mean Concentrations, Levels of Detectable (Significant) Increase,
and the NOAA ER-L Values for Sediments within 2 km of the Diffuser.
(Metals in ppm; organics in ppb)

Mean Sediment
Contaminant | Concentration

Silver 0.16
Cadmium 0.05
Chromium 50

Copper 15
Mercury 0.12

Nickel 12

Lead 44

Zinc 39
Total DDT 0.8
Total PCB 79
Chlordane 0.05
Total PAH 2061

NOAA Representative
Detectable Change’ ER-L Boston Harbor
(Within 2 km of diffuser) | Value Concentrations?
0.35 1 2.8 (0.14 to 7.9)
0.4 1.2 1.0 (0.04 to 3.9)
val 81 142 (32 to 385)
24 34 98 (11 to 219)
0.22 0.15 0.8 (0.039 to 3.75)
20 24 26 (7.4 to 43)
53 47 146 (25 to 419)
53 150 184 (31 to 407)
23 1.6 59 (1.1 to 207)
145 22.7 193 (7 to 855)
0.16 05 Not measured
4395 4022 30,717 (380 to 156,200)

‘The lowest hypothetical concentration that would be interpreted as a significant increase
over 1994 concentrations based on statistical analysis.
2Values from Durell (1995) are presented as: average (min to max).

Source: Hunt et al., 1995

& MWRA has conducted modeling
studies to evaluate future conta-
minant loads in the bays. These
models have demonstrated that
within the estimated 50 year
lifetime of the treatment plant,
the addition of metals through
the outfall will result in minimal
increases in the overall concen-
trations of metals in bottom
sediments.

Analytical Chemistry

Data in this report are presented
as both wet weight and dry
weight. Fish and shellfish tissue
data are reported as wet weight,
where as sediment data are pre-
sented on a dry weight basis.

NOAA ER-L screening values presented in Table 4-5; all were well below NOAA ER-M levels.
The third column of the table indicates that the monitoring program is appropriately
designed to measure variations of contaminant levels in sediments and that it will be suffi-
ciently sensitive to detect changes that could cause exceedance of action or warning levels.

In addition to its sediment sampling program, the MWRA and the U.S. Geological Survey
are engaged in a joint study of contaminant transport in the vicinity of the future outfall.
Metals such as silver, whose major current source to the bays is the existing MWRA effluent
discharge, are tracked in this joint effort. Consistently stable levels of silver have been
observed by the USGS between 1989 and 1992 (Figure 4-1). In general, silver concentra-
tions during this period averaged between 0.5 and 0.7 mg/kg; however, in February 1993, a
significant increase in silver concentrations was seen. This increase in silver may be related
to sediment transport and accumulation of fine material following the major northeast
storm of December 11-16, 1992. This finding demonstrates the importance of sediment
transport processes in determining the concentration and distribution of toxic materials in
sediments.

4.4.3 Tissue Analyses
Flounder & Lobster Studies

Between 1992-1994, the MWRA conducted annual sampling of winter flounder and lobster
in Massachusetts Bay. The primary goals of this monitoring program are: (1) to evaluate
the health of these marine resources in terms of disease (Section 4.4.4) and (2) to evaluate
organic and inorganic contaminant concentrations in the organs and edible tissues of these
organisms.

MWRA : 0U'

Winter flounder were collected from five sites in Boston Harbor and
the bays: Deer Island Flats, Broad Sound, Nantasket Beach, the
Future Outfall Site, and a reference site in eastern Cape Cod Bay
(Figure 4-2). Lobster were collected from the Deer Island, Future
Outfall, and eastern Cape Cod Bay sites.

In 1994, contaminant concentrations were measured in 15 flounder
muscle samples, 15 flounder liver samples, eight lobster muscle
samples, and eight lobster hepatopancreas samples at each site. All
samples were analyzed for PCBs, chlorinated pesticides, and mer-
cury. The liver and hepatopancreas samples were also analyzed for
a number of other organic and inorganic contaminants.

The monitoring results indicate that contaminant concentrations in
flounder and lobster are generally higher in Boston Harbor near the

L MONITORING OVERVIEW REPORT: 1994 / 23

Ag (ppm)

2.0

T111T

1.5

poi

TIT

piri

2 4
BRE 8

existing Deer Island outfall and at the future outfall site than at the Cape Cod Bay site.
Contaminant concentrations at the future outfall site are generally intermediate between val-
ues at Deer Island and the Cape Cod Bay site. However, the data were highly variable and
PCB and mercury concentrations in lobster and mercury in flounder were higher at the

future outfall site than at Deer Island in 1994 (see Figure 4-3).

Long term monitoring data indicate that over the past decade there has been a general
decline in contaminant concentrations in fish and shellfish in Boston Harbor. Mercury con-
centrations in flounder tissue from the MWRA studies and an earlier study were compiled
for the Deer Island sampling station (Figure 4-4). These data suggest that tissue concentra-

tions of mercury decreased by approximately a factor of two
between 1987 and 1994.

Over the past few years, temporal variations in the concen-
trations of various contaminants in flounder and lobster
have been mixed, with some increases and some decreases.
For example, at the Deer Island site PCB concentrations in
flounder increased by over a factor of two between 1993
and 1994, while mercury in flounder decreased during the
same period. At the future outfall site, most contaminants
increased between 1993 and 1994. During this period, PCBs
and chlordane in lobster increased by approximately a fac-
tor of three and DDT increased by a factor of two. These
variations are likely due to a number of complex factors,
including analytical variability, migration of animals, the
transport and mobility of contaminated sediments and the
effects of exposure of fish and shellfish to contaminants in
sediments and resuspended sediments. In general, it is
expected that outfall relocation will result in decreased cont-
aminant levels in harbor fish and shellfish, without any sig-
nificant increases at the future outfall site.

6 8

ava be
pea ef

10 16
Sow va Be
ESSE ee ER

Survey Date

FIGURE 4-1

Concentrations of silver in the
surface sediment layer near the
future outfall in Massachusetts
Bay: 1989-1994. Bars represent
one standard deviation on
mean of data. (Source: Bothner,
et al., 1993)

STATIONS:
1 — Deer Island O1

2 — Nantasket Beach - flounder
3 — Broad Sound ~ flounder

4 — Future Outiall

5 — Cape Cod Bay Site - flounder, lobster
6 — NE. Aquarium Discovery Site ~ mussels

Bay

Massachusetts

utfall - flounder, lobster, mussels

Site - flounder, lobster, mussels

Cape Cod Bay

FIGURE 4-2

Sampling stations for winter
flounder, lobster and mussels
during 1994.

24/ OUTFALL MONITORING OVERVIEW REPORT: 1994 : MWRA

@ When contaminants are stored
in fish and shelifish tissues,
they are said to bioaccumulate.
Tissue analysis to determine the
contaminant body burden pro-
vides useful information for
evaluating risks to human
health and the environment
from food chain exposure.
However, many organisms are
known to bioaccumulate toxic
chemicals without exhibiting
adverse health effects.

FIGURE 4-3

PCB and mercury concentrations
in flounder muscle and lobster
meat, 1992 to 1994. (Lines rep-
resent range of data).

Source: Hillman and Peven,

Mercury in Flounder Meat PCB in Flounder Meat

120

Concentration (ppb wet wt}

FOS ccB

BS
Site Location

Diese Bi 1903 EE} 1098

BS
Site Location

Ci ts92 fil 1999 EE) 1904

Mercury in Lobster Meat PCB in Lobster Meat

Concentration (ppm wet wt.)
Concentration (ppb wet wt.)

CCB

Fos
Site Location
BiB 1985 (1002 MB 1909 E1808

DI = Deer isiand Outfall NB=NantasketBeach BS=BroadSound FOS = Future Outfail Site

FOS.
Site Location

|Mllises (7) 1992 BB 1993 Ea) 1204

CCB = Cape Cod Bay Site

Historical monitoring data have demonstrated that contaminant levels in

tissues of lobster and flounder are well below applicable action levels in
Massachusetts Bay. The MWRA's baseline monitoring data support this

finding even with the recent increase in tissue contaminants at the
future outfall site and Deer Island. A comparison of PCB and mercury

concentrations in various tissues with the U.S Food and Drug
Administration Action (FDA) Levels for these contaminants in edible tis-
_ sue (thresholds for toxic contaminants in tissue are based on these
action levels) indicates that the detected concentrations were at least
four times lower than the FDA action level. PCB concentrations in lob-
ster hepatopancreas were the closest to the action levels, ranging from 4
times lower at the future outfall site to 15 times lower in the Cape Cod

1995.
02

z

2

2 —

=

3 0.15 =

3 —_
E

5

&

ge

2 o1

£

5

8 _

2

8 6.05 —

0

5

2

5

2

t)
1987 1988 1989, 1990 1992, 1993 1994

FIGURE 4-4

Mercury concentrations in floun-
der meat from Deer Island, 1987
to 1994. (Lines represent one
standard deviation).

Source: Hillman and Peven,
1995.

Bay site.

Bioaccumulation in Mussels

A series of mussel bioaccumulation studies have been conducted since 1987 to determine
whether selected contaminants (PCBs, pesticides, PAHs, and metals) bioaccumulate in
shellfish. This study was also used to obtain background data offshore in the vicinity
of the future outfall site. Mussels were collected from a relatively clean location in
Gloucester, MA and deployed in cages at three locations (Figure 4-2): near the present
Deer Island outfall; at the future outfall site; and in the inner harbor (the New England
Aquarium Discovery barge). After 60 days, mussels were harvested for biological and
chemical analyses. Overall, study contaminant levels at the Boston Harbor stations
(Deer Island and Discovery) have decreased since 1987. For example, as shown in
Figure 4-5, PCB levels near the Deer Island outfall decreased by approximately a factor of
three between 1986 and 1994.

MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1994 / 25

e 02

In 1994, contaminant concentrations ®
were generally lowest at the future out- ia o1eL
fall site and highest at the Deer Island 3

+ . . °
and Discovery stations. For example, in Bo 2 ° °
1994 the average total PAH concentra- od
tion in control mussels from the g ° °
Discovery Station (2255 ppb) was signifi- = 0.08 .
cantly higher than in all other mussel 8 . °
deployment groups. Likewise, in 1994 8 0.04 |- é ° °
the average concentration of total PAH in oO °
Deer Island mussels (848 ppb) was sig- g ott ! 1 L 1 L i ! 1
nificantly greater than the average total 1986 1987 1988 1989 1990 1991 1992 1993 1994
PAH concentration in mussels from the @ MWRa Data Year

. NOAA Status and Trends Data

future outfall site (122 ppb). source: Hal pers. comm FIGURE 4-5

Total PCB body burdens in mussels at all stations were generally lower in 1994 than in the
previous year (Table 4-6). None of the stations had PCB concentrations that exceeded the
action levels. The Discovery mussels typically had the highest observed PCB concentra-
tions, while the mussels deployed at the future outfall location had the lowest concentra-
tions of PCBs. Mussels caged at the future outfall site in 1993 and 1994 contained contami-
nant levels equal to or less than levels at the Gloucester predeployment location. This
demonstrates that no bioaccumulation of PCBs is currently occurring at the future outfall
site (Table 4-6).

4.4.4 Abnormalities in Marine Life

Some winter flounder from all sampling sites, including the future outfall site, had fin ero-
sion or a number of different histopathological liver lesions. One sensitive indicator of con-
taminant exposure is the prevalence of a liver lesion known as centrotubular hydropic vac-
uolation (CHV) in fish livers.

The National Marine Fisheries Service and researchers from Woods Hole Oceanographic
Institute have monitored tumors in flounder since the late 1980's. Since 1991, the MWRA
has monitored the presence of CHV and other tumors in flounder from Boston Harbor and
the bays. These studies have consisted of annual sampling of 50 winter flounder from five
different locations. Sampling results to date indicate that the incidence of CHV in winter
flounder from the vicinity of the future outfall site has been relatively constant since 1991
(Figure 4-6). In contrast, tumors in Boston Harbor flounder decreased significantly in the
late 1980s.

CHV has been present in about 30% of the fish population from the future outfall site, sig-
nificantly less than the approximately 50% incidence in flounder in Boston Harbor. The
lowest prevalence (<10% in 1994) of CHV occurs at the eastern Cape Cod Bay reference
site.

Comparison of CHV occurrence with contaminant levels indicates that the prevalence of
this disorder increases with increasing contaminant concentration. Figure 4-7 shows this
trend for PCB concentrations, indicating that CHV occurrence in flounder is correlated with
PCB levels. The causes of CHU, however, are not known at present.

Total PCB Bioaccumulation
in mussels near Deer Island
discharge, 1986-1994

Fish and Shellfish
Action Levels

@ The U.S. Food and Drug
Administration (FDA) has estab-
lished action levels for toxic or
deleterious substances in
human food and animal feed.
Action levels represent limits at
or above which FDA may take
action to remove products from
the market. For example, the
FDA legal limit for contaminants
in fish and shellfish is 2.0 ppm
for total PCBs and 1.0 ppm for
mercury.

= The presence of physical
abnormalities in fish and
shellfish can be a sensitive
indicator of contaminant expo-
sure. Tumors, lesions, finrot,
and gross deformities are
physical abnormalities that
may be attributable to pollution.
Certain physical abnormalities
such as liver lesions may only
be detected through histopathol-
ogy, the study of adverse
changes in tissue structures.

26 / OUTFALL MONITORING OVERVIEW REPORT: 1994 : MWRA

TABLE 4-6
Comparison of Average Body Burdens of Deployed Mussels
for Select Organic Compounds and Metals

1993
Pesenete [owe | cerisins | ozone Predeployment Future Deer Discovery
Parameters Gloucester | Outfall Site | Deer Island Discovery Gloucester | Outfall Site Island Average
PAH (ppb wet weight)
LMW PAH 13,2 13.2 33.8 22 21.2 12.2 43.4 15.8
HMW PAH 24.4 20.2 99.2 242 31.6 12.2 126 435
Total PAH 37.6 33.2 133 264 52.8 24.4 170 451
Pesticides (ppb wet wt)
Total Chlordane 3.2 2.2 48 5.2 2 18 5.4 5.8
Total DDT 16.4 6 12.6 26 54 3.8 10 17.2
Polychlorinated Biphenyls
(ppb wet weight)
Total PCB 478 22 64.2 119 21.4 178 32.2 100
Metals (ppb wet wt}
Mercury 0.078 02 036 036 0.026 0.042 032
Lead 1,024 742 1.176 1.72 96 18 1.33
Source: Downey et al., 1995.
80
Mean Harbor prevalence, 1984-1989
)
© go}
8 Mean Harbor prevalence, 1991-1994
& |
$ 40
FIGURE 4-6 a
Prevalence of CHV near the >
future outfall site: 1991-1994. 3 20) |- me
CHV=Centrotubular Hydropic :
Vacuolation. Source: Hillman r 7 a . eo.
and Peven, 1995. 9 ot g2 93 94
Year
80
Q Deer Island Flats 1992
> Broad Sound °
© Future Outfall Site
6074 A Nantasket Beach
~ f Eastern Cape Cod Bay a 1994
2 a
z
sg
3
FIGURE 4-7 z
Total PCBs in Flounder Liver z
Tissue vs. CHV Prevalence. é
Source: Moore & Stegeman
1993; Shea 1993; Hillman et al.
1994; Hillman & Peven 1995
ty)

T T T
0 1000 2000 3000

Total PCBBs in Flounder Liver (ppb dry wt)

4000

5.0 Human Pathogens

5.1 Water Quality/Health Issues

Human pathogens in effluent are bacteria and viruses from human and animal waste that
cause disease in humans. Although human pathogens are not known to harm marine life,
they may concentrate in filter feeding shellfish, such as mussels and clams. Human expo-
sure to pathogens may occur primarily from the consumption of contaminated shellfish and
from incidental ingestion of water while swimming. Fecal coliform bacteria are often used

as an indicator of the presence of human pathogens. FIGURE 3-1
Measurements of

Pathogens in wastewater are Fecal Coliform in Effluent

commonly controlled by disin- 1,000,000
fection, generally by chlorina-
tion. Also, pathogens die off
very quickly in sea water and
the effect of pathogens dis-
charged in marine waters are
typically very localized near an
outfall, MWRA’s new outfall

Daily mean of 3 measurements
moma Vionthiy mean
100,000 4 |

farmerein

10,000 3

Il

Daily max = 400

1,000

go

location is far from beaches and

Monthly max = 200

shelifishing areas, which will
minimize the potential for
human exposure. Computer
modeling studies have indicated
that, even in the unlikely cir-
cumstance of a complete failure 1

100

pout

Fecal Coliforms per 100 ml

10-44 a | y

0
of the disinfection system, dis- JFMAMJJASONDJFMAMJJASONDJFMAMJJASOND
charges from the new outfall 1992 1993 4994
location would result in insignif-
icant pathogen levels at the nearest beaches, Nahant and Nantasket Beach.

5.2 Trigger Parameters and Thresholds

Trigger parameters and thresholds for bacterial indicators of the presence of human
pathogens were based on state water quality standards and designed to measure the dis-
charge of pathogens that might lead to unacceptable exposure to humans. Established
action levels are:

H Daily mean greater than 400 fecal coliform/100 ml in effluent.

H# Monthly mean greater than 200 fecal coliform/100 ml in effluent.

5.3 Monitoring Program Components Designed
to Address Issues
Because the effluent will be diluted at the new outfall, it is unlikely that any bacterial water

quality standards would be exceeded if undiluted effluent bacteria concentrations were less
than the action levels. In order to ensure that pathogen levels are below action levels, the

28 / OUTFALL MONITORING REPORT: 1994 + MWRA

MWRA monitors fecal coliform levels in the effluent three times each day. Long-term moni-
toring for pathogen indicators in the Massachusetts Bay receiving waters is not necessary,
as long as the diffuser design dilution is met and effluent monitoring indicates that effluent
quality is within the permitted limit.

5.4 Monitoring Program Results

Fecal coliform levels in Deer Island effluent vary widely (Figure 5-1). Although these
results show that on occasion the fecal coliform levels in 1991 and 1992 exceeded daily
threshold values, the monthly averages during this time period were below effluent stan-
dards. This level of performance is expected to be further improved when the new treat-
ment plant is on-line. The new treatment plant will have a longer chlorine contact time,
resulting in increased pathogen destruction.

MWRA - OUTFALL MONITORING REPORT: 1994 / 29
; B Benthic it
6.0 Solids eto soe

Diversity is often used to

evaluate environmental
6.1 Water Quality Issues change. Examples of
Suspended solids are small particles of matter, such as mud, sand, or organic debris, sus- changes in community diver-
pended in the water column. Solids have an important influence on the behavior of toxic sity include changes in the
contaminants and other water quality parameters. However, the primary concern associat- relative abundance of vari-
ed with solids is deposition and the resulting potential for smothering of bottom habitat and ous species, or changes in
benthic (bottom dwelling) organisms. Another issue of some concern is the aesthetic effect the numbers and kinds of
of loss of clarity of waters with high suspended solids levels. species that live in a

particular habitat.

6.2 Trigger Parameters and Thresholds

‘Trigger parameters and thresholds for solids for the effluent were developed based on
expected NPDES permit limits, which should protect the receiving water body from solids
discharges. Other threshold values provide a measure of impacts on the benthic biological
community. Established threshold values for solids are shown on Table 6-1.

Thresholds for carbonaceous BOD and depth of sediment DO discussed above are also rele-
vant for identifying the impact of solids.

6.3 Monitoring Program Components Designed
to Address Issues

The MWRA monitors the environmental impact from solids in the following ways:
— Concentrations of total suspended solids are measured daily in the effluent.

@ In cooperation with the USGS, the MWRA monitors suspended solids at the future
outfall site and sediment depositional patterns and trends throughout
Massachusetts Bay.

TABLE 6-1

Trigger Parameters and Threshold Values for Solids

Basis for Trigger Parameter and
Trigger Parameter Threshold Values Threshold Values

Effluent TSS Warning Levels: ~ Provides measure of total suspended
Concentrations — Weekly mean effluent total suspended solids (TSS) greater than solids loading to bay.
40.5 mg/L. ~ — Warning levels for effluent based on
- Monthly mean effluent TSS greater than 27 mg/L. 90% of expected NPDES permit limit.
~ — Action levels for effluent based on
Action Levels: expected NPDES permit limit.

~ Weekly mean effluent TSS greater than 45 mg/L.
- Monthly mean effluent TSS greater than 30 mg/L.

Benthic Community Warning Levels:

— Mean benthic community diversity at neartield muddy or sandy ~ Provides measure of benthic

stations decrease by 50%. commurty heat ;
= Significant downward trend in mid-field benthic diversity for 3 ~ fiery is based on community

post-discharge years.

- Change in mid-field soft bottom community to typical degraded
benthic community.

~ Significant difference in species composition and relative abun-
dance at stable mid-field soft bottom sites relative to baseline.

$0 / OUTFALL MONITORING REPORT: 1994 - MWRA

What is a Benthic
Community?

@ A marine benthic community is
composed of organisms such as
worms or crustaceans dwelling
on or in the sea floor (see Figure
6-1). Benthic communities in
Massachusetts Bay include
numerous marine invertebrate
and fish species.

Why Evaluate the
Benthic Community?

H Benthic communities reflect the
overall ecological quality of an
area. Surveys of communities
can provide sensitive measures
of effects from physical and
chemical stressors such as
sewage effluent toxicants and
organic matter. Benthic inverte-
brates are useful indicators of
potential impacts associated
with stressors because:

- Some benthic organisms are
commercially important
species.

~ Benthic organisms are a pri-
mary food source for many
recreationally and commer
cially important fish species.

~ Many species have limited
mobility, so they cannot move
away from stressful condi-
tions.

- Sensitive life stages exist for
most species.

- Sampling is relatively routine
and cost-effective.

— There is a large literature
database available to assess
impacts.

- Degraded conditions can be
readily detected using modern
automated methods.

Sediment sampling and video inspection of the sediments in the immediate
vicinity of the outfall are conducted.

@ TSS, turbidity and light penetration are measured as part of water column
monitoring.

@ Benthic communities can serve as sensitive indicators of environmental perturba-
tions. For this reason, the MWRA monitors numbers and types of benthic organ-
isms in Boston Harbor, in the vicinity of the future outfall site, and throughout the
rest of Massachusetts and Cape Cod Bays.

In addition, other parameters such as the depth of oxygenated sediment are used to
monitor environmental impacts from solids. This information is presented in Section 2.0
of this report.

6.4 Monitoring Program Results
Effluent

Average monthly TSS concentrations in the effluent from the Deer Island Treatment Plant in
1994 ranged from 65 to 90 mg/L. On average, of 44% of the solids entering in the influent
to the Deer Island facility were removed following primary treatment. In January 1995, the
MWRA began monitoring effluent TSS from the new Deer Island Primary Treatment Plant.
Preliminary 1995 data suggest that total solids levels in the effluent are slightly lower than
in 1994 (65 to 65 mg/L in the first third of 1995). Although the TSS appears to be lower in
the new plant effluent, these values are still substantially higher than the established
threshold values. The MWRA anticipates that completion of the new secondary treatment
facility will further improve effluent water quality, and that TSS levels will drop substantial-
ly once secondary treatment commences. The TSS level for the secondary treatment plant
is expected to be approximately 15 mg/L.

Benthic Habitat/Community Monitoring

The assessment of benthic community changes in response to effluent quality requires a
thorough understanding of the benthic habitat, as well as the existing community structure,
function, stability, and variability. Numerous factors other than effluent discharge have the
potential to affect benthic community composition. The complex and variable habitat and
environment in Massachusetts Bay — especially in the vicinity of the future outfall diffuser
— are important considerations in the assessment of benthic communities. Western
Massachusetts Bay, including the nearfield future outfall site area, is a region of highly vari-
able bottom habitat types. Erosional (representing hard bottom, cobbles, rock and/or grav-
el), depositional (representing soft bottom mud and fine-grain sand), and mixed environ-
ments are widely interspersed (see Figure 6-2). Typical habitat patch sizes are on the order
of hundreds of meters. There is strong evidence that some of these sediments are highly
dynamic, showing dramatic changes after major storm events. In contrast, Cape Cod Bay
has a relatively homogeneous, stable bottom environment.

Between 1992 and 1994, 170 benthic samples were collected. The database from these
samples lists 244,040 organisms representing 322 species. The data indicate that the benth-
ic community is strongly influenced by bottom habitat type. Therefore, communities in
western Massachusetts Bay show strong shifts over relatively small distances. However,
widely separated stations with similar sediment types often show very similar benthic com-

MWRA + OUTFALL MONITORING REPORT: 1994 / 31

Annelida Polychaeta
Sternaspidae -
Sternaspis scutata

AN
Figure from Bousfield, 1973, reproduced courtesy of the Canadian

“ Museum of Nature, Ottawa, Canada

SS Illustrator: Ruth Von Arx

f

nd
Yoyo A
Ai 53 ‘ Crustacea
a AWD : Cumacea
SS Diastylidae -
— 4 Diastylis Sculpta
Annelida 7 .. | Figure from
Polychaeta ) Watling, 1979
Capitellidae — Illustrator:
Margaret Macy phoronida —
Phoronis architecta

Heteromastus
filiformis,
anterior portion

Figure after
Wilson, 1881

Gastropoda Nassariidae -

Ilyanassa trivittata
Figure from R. 1. Smith, 1964

Illustrator: Ruth Von Arx

HN

Echinodermata Asteroidea —

Mollusca Bivalvia Arcticae -
Arctica islandica Ctenodiscus crispatus
Figure from Weiss, 1995
Illustrator: Lauren Churchill

Figure from Weiss, 1995
Illustrator: Lauren Churchill ait

FIGURE 6-1
Benthic organisms collected in

Massachusetts Bay

$2 / OUTFALL MONITORING REP

Soft Bottom and Hard
Bottom Benthic
Communities Differ

@ The benthic community inhabit-
ing the soft silty sands that
characterize soft bottom regions
of Massachusetts Bay differs
vastly from the community
dwelling on the rocks and
cobbles that make up the hard
bottom. Soft bottom or infaunal
organisms include various worm
and invertebrate species that
tunnel into the silty sediments,
whereas hard bottom or epifau-
nal species include animals such
as shellfish, crabs, and
anemones that dwell on the
surface of the rocky ocean floor.
Different techniques are used

to evaluate the benthic commu-
nity in these two differing
habitats. Figure 6-2 shows the
varied sea floor environments
of Boston Harbor and
Massachusetts Bays.

FIGURE 6-2

Sea Floor Environments
Within the Boston Harbor ~
Massachusetts Bay
Sedimentary System

USGS Web Site:
http:\\vineyard.er.usgs.
gov\arc\data\seafloor.gif

: 1994 > MWRA

1
S230 TON

Sedimentary Environmoants,

Evosiox oc Noodeposition
MM ettecos wien Isolated Reftectiona
Patteeng of Strong Backscatter

Sediment Reworkisg ra
L. [Paterna with Patches oF Strong IS
__ Weak Backnsaner iS

ie

GM Patere of Weak Backsrattcr

x

A

1
> $a 108 15.9 Kilometers
a

munities. Generally, year to year benthic community changes in the near field during base-
line monitoring correspond to changes in sediment characteristics. Stations where little sed-
iment change has occurred since 1992 show relatively small changes in the number and
type of organisms found, while stations in areas with major changes in sediment type show
equally dramatic changes in the benthic community. For example, one site changed from
70% mud to 95% sand between 1992 and 1993. Correspondingly, the benthic community
changed from one characterized by numerous species of polychaetes (small marine worms)
to one overwhelmingly dominated by a single bivalve mollusc species.

Statistical analyses will be used to evaluate any changes in the benthic community resulting
from effluent discharge through the new outfall. MWRA is currently evaluating promising
statistical methods that will allow differentiation between naturally occurring spatial and
temporal variability such as that measured during baseline monitoring, and meaningful
changes or impacts from sewage effluent after outfall relocation.

7.0 Floatables

7.1 Water Quality Issues

Floatables are pollutants, such as plastic materials, oil, and grease, that float on the surface
of the water. Floatables are primarily an aesthetic problem, but may cause harm to marine
life. In addition, oil and grease can affect the taste and odor of seafood.

7.2 Trigger Parameters and Thresholds

Thresholds have been established to measure whether floatables are removed as expected
and whether the oil and grease discharge is within NPDES limits. Action levels are:

Greater than 5 gallons per day of floatables collected in a series of floatables
collection devices.

& Maximum petroleum oil and grease concentration in effluent greater than
15 ppm.

7.8 Monitoring Program Components Designed
to Address Issues

The MWRA has already made significant reductions in floatable discharge. Scum and
sludge discharge has ceased, dramatically reducing the volume of floatable material dis-
charged. In addition, the new Deer Island Treatment Plant includes state-of-the-art mecha-
nisms for removing floatables. To evaluate floatables before discharge, the MWRA makes
regular observations of wastewater during treatment to ensure that floatables are removed
as expected, and that oil and grease discharges are within the NPDES permit limitations.

If the MWRA detects floatables in the effluent, it will review the treatment plant operations
and take steps to remedy the problem.

7.4 Monitoring Program Results

Current sewage treatment operation includes routine and efficient removal of floatable
materials early in the treatment process. As a result, substantial levels of floatables have
not been detected in the effluent.

$4 / OUTFALL MONITORING REPORT: 1994 : MWRA

8.0 Summary of Monitoring Program

The baseline monitoring program has focused on the following six wastewater constituents
for determining the environmental impact of coastal discharges of treated sewage:
@ Nutrients

Organic Material
Toxic Contaminants
Pathogens

Solids

@  Floatables

For organizational purposes, these six parameters were divided into four major monitoring
areas: effluent, water column, benthic, and fish and shellfish. Twenty baseline measure-
ment parameters were defined as key monitoring parameters for the monitoring program
(Figure 8-1). A summary of the monitoring program is presented in Table 8-1.

8.1 Effluent Monitoring

The primary objective of the effluent monitoring program is to characterize waters dis-
charged from the Deer Island treatment plant. Concentrations and variability of chemical
and biological constituents in the treatment plant effluent
are measured. These data will be compared to NPDES per-

Effluent

mit limitations and evaluated to determine loadings and bissolved
potential impacts on Massachusetts Bay. Solids BoD Chlorophyll Oxygen
Toxic . Nuisance
Water samples are collected at the Deer Island treatment Contaminants Floatables Nutrients Algae
facility and analyzed for nutrients, priority pollutant organ- teal
ics and metals, pathogens, and oil and grease. Pathogens Nutrients Solids Community

To date, with only primary treatment in operation, the efflu- Benthic Shellfish |
ent monitoring program has demonstrated that certain met- Redox
" Toxic

als and organic compounds in undiluted effluent exceed ; isventaty Contaminants Pathology
marine water quality criteria. However, the MWRA antici- Coramunity
pates that approximately a 100 fold dilution of the effluent Nutient round Pounder

JUX lounder
will occur within a few tens to hundreds of meters of the Lobster

Flounder and
Lobster
Extemal

Abnormalities eS

Sediment
Toxic
Contaminants

diffuser. This dilution will ensure that the chemicals in Mussels

effluent water will pose a minimal risk to aquatic life. In
addition, as the MWRA upgrades to secondary treatment of

FIGURE 8-1

sewage, further reductions in organic content and toxic compounds in the effluent are antic- — yyypa monitoring plan:
ipated. Monitoring areas and endpoint
parameters

8.2 Water Column Monitoring

The water column monitoring program is designed to provide measurement of water quality
and plankton data in Massachusetts Bay and Cape Cod Bays. Water column monitoring
program data will help detect changes in the water column of Massachusetts and Cape Cod
Bays resulting from the relocation of the effluent outfall. Water quality and plankton data

36 / OUTFALL MONITORING REPORT: 1994 : MWRA

Summary of MWRA Monitoring Program

Task Objective Sampli cations and Schedule Analyses
EFFLUENT MONITORING |
Effluent Sampling Characterize wastewater Monthly * Nutrients

TABLE 8-1

throughout Massachusetts

* 26 locations (See Figure 2-4}

discharged from Deer Island | * Daily * cBOD
Treatment Plant * Monthly * Toxic contaminants
© 3Times/Day + Pathogens
* Daily * Solids
* Weekly * Oil & Grease
« Weekly + Floatables
WATER COLUMN MONITORING
Neartield Surveys Collect water quality data * 17 surveys/year * Temperature * Nutrients
Near outfall location * 21 locations (See Figure 2-4) « Salinity * Total Suspended
* Dissolved oxygen Solids
« Chlorophyll * Plankton
Collect water quality data * 6 surveys/year * Temperature * Salinity

* Dissolved oxygen * Nutrients

and Cape Cod Bays * Chlorophyll * Plankton
Fartield Surveys * Total suspended
solids
Plume Track Surveys | Track location and * 3-4 surveys/year * Salinity
characteristics of ¢ Temperature
discharge plume * Dissolved oxygen
* Chlorophyll
* Total suspended solids
Continuous Provides continuous * Continuous monitoring * Temperature
Monitoring water quality data * Single station * Salinity
near outfall ° 3 depths * Optical beam transmittance

Remote Sensing

Nutrient Flux Surveys

Evaluate outfall impacts
on a regional scale
through satellite imagery

Evaluate nutrient interactions
between the sediment
and water column

¢ Approximately 1/month

* 5 surveys/year
* 7 locations (See Figure 8-2)

* Temperature
* Chlorophyll

BENTHIC MONITORING

* Oxygen demand
* Nutrient flux
* Porewater nutrients

Soft Bottom Surveys

Evaluate sediment quality
in Boston Harbor
and Massachusetts Bay

* 8 Boston Harbor stations

(See Figure 8-3)
* 20 nearfield stations (See Figure 8-4)
11 farfield stations (See Figure 8-4)

* Sediment chemistry
* Benthic community composition

Hard Bottom Surveys

Characterize marine
communities in rock

* 1 survey/year
* 6 transects (See Figure 8-5}

* Topography
« Substrate

and cobble areas * Benthic community composition
FISH AND SHELLFISH MONITORING
Flounder Studies Determine contaminant * 1 survey/year * Tissue contaminant concentrations
body burden and * 5 locations (See Figure 4-2) * Physical abnormalities
population health (including histopathology)
Lobster Studies Determine contaminant * 1 survey/year * Tissue contaminant concentrations
body burden * 3 locations (See Figure 4-2) * Physical abnormalities

Mussel Studies

Evaluate biological
condition and short-term
contaminant bioaccumulation

* 4 survey/year
* 3 locations (See Figure 4-2)

* Tissue contaminant concentrations
* Physical abnormalities

are being collected in Massachusetts Bay and
Cape Cod Bay in order to characterize water
column conditions before completion of the
outfall. Once the outfall is on-line, water col-
umn monitoring data will be compared to back-
ground data and any impacts to Massachusetts
and Cape Cod Bay will be assessed.

To date, the water column monitoring program
has demonstrated that the Massachusetts and
Cape Cod Bay system is dynamic, with consid-
erable spatial and temporal variability. The
influence of seasonal cycles and differing eco-
logical environments must be considered when
evaluating the potential influence of the MWRA
upgrades within this marine system.

LL MONITORING REPORT: 1994 /

a - not 4neagr00"

The five major components of the water col-
umn monitoring program, nearfield surveys,
farfield surveys, plume track surveys, continu-
ous recording, and synoptic overview, are out-
lined below. These components are designed
to provide comprehensive coverage of water
quality conditions in Massachusetts and Cape Cod Bays.

70°55'00" 70"s0'00"

Nearfield Surveys

Nearfield water column surveys are designed to collect frequent, intensive sets of water
quality and plankton data near the outfall location. Data are collected at 21 locations
(Figure 2-4) in 17 annual surveys. These surveys provide vertical profiles of physical,
chemical, and biological water column characteristics throughout each year, identifying
seasonal cycles and events of interest

_— e . <4 4nnsoo
a ar 4! gewoor
4251500"
7 _ - rage"

FIGURE 8-2
Benthic Nutrient Flux Sampling
Locations

FIGURE 8-3
Boston Harbor Soft Bottom
Benthic Stations

(e.g. algal blooms).

During each nearfield survey, temperature,
salinity, dissolved oxygen, chlorophyll fluo-
rescence, light transmission, and photosyn-
thetically available light are measured in
situ throughout the water column. Water
samples are collected throughout the water
column for laboratory analysis of con-
stituents including nutrients, chlorophyll,
TSS, DO, phytoplankton, and zooplankton.

15a ©

Be a.
oN -
Longisiand ©
“i
¥ itn a
Dorchester Bayi LO
acon
uli Bay
ee ac
a

Nut island
) Grape Isiand
9

Farfield Surveys

Farfield water quality surveys are designed
to collect intensive sets of water quality,
plankton and primary productivity data

0 3
LS =z
MILES

38 / OUTFALL MONITORING REPORT: 1994 «

FIGURE 8-4
Locations of Soft Bottom
Benthic Stations

over a broad spatial scale, including Massachusetts
and Cape Cod Bays. The purpose of the farfield
surveys is to determine differences across the bays
and assess seasonal changes over a large area, (¢.g.
relating trends observed in the nearfield area to the
surrounding region).

42°30'00"

Six farfield surveys are conducted each year collect-
ing water quality, plankton and primary productivi-
ty data at 26 stations throughout Massachusetts and
Cape Cod Bays (Figure 2-4). In situ measurement
and water sampling performed during farfield sur-
veys is comparable to the nearfield sampling
described above.

42"15°00"

42"00°00"

Plume Tracking Surveys

Plume tracking surveys are performed to determine
the location and chemical and biological character-
istics of the effluent discharge plume leaving the
outfall and mixing with ambient waters. Once the
outfall is on-line, several surveys per year will be
performed near the outfall location. These data will
be helpful in understanding the migration of the
discharge effluent. Sampling will include measurement of salinity, temperature, DO, chloro-
phyll, and total suspended solids. Some preliminary plume tracking studies of an explorato-
ty nature have been performed.

4ay%4s'00"

Continuous Monitoring

The continuous monitoring component of the program is designed to provide continuous
water quality data. The purpose of continuous monitoring is to capture temporal (ie.,
time-dependent) variations in water quality in between nearfield water quality surveys.
Continuous monitoring data includes measurement of temperature, salinity, and optical
beam transmittance at three depths at a single mooring station in Massachusetts Bay near
the future outfall location.

Remote Sensing

Remote sensing is designed to capture spatial variations in water quality on a regional scale.
Remote sensing via satellite provides a snap shot of water quality data, such as
Massachusetts Bay and Boston Harbor sea surface temperature and chlorophyll. This com-
ponent creates a spatial link among survey sample locations.

8.3 Benthic Studies

The benthic studies program is designed to provide measurement of the benthic environ-
ment in Boston Harbor and Massachusetts Bay. The goals of the benthic program are two-
fold. The first objective is to document the recovery of benthic conditions in Boston Harbor
following the cessation of sludge discharge and improvements in CSO treatment and dis-

akm

charge. These data will provide
valuable information on bottom
sediment response and benthic

ecosystem recovery.

42° 24N

Latitude

The second objective is to collect
background data on the physical,
chemical, and biological process-
es in the benthic environment
near the outfall location in
Massachusetts Bay. These data
are essential to assessing poten-
tial impacts of effluent dis- 5
charged near the outfall on the 70" OW 70 40W 70° aw 7oa7-W 7oraerw Distance
surrounding benthic ecosystem.

42° 223N |

Longitude

FIGURE 8-5

Location of nearfield hard
To date, the benthic monitoring program has provided valuable baseline information on the bottom benthic survey
status of the benthic environment in the system. The complex physical environment in transects. Inset shows the
Massachusetts Bay, especially near the diffuser, makes the assessment of the benthic envi- study-area locations within

Massachusetts Bay.

ronment particularly difficult. In general, the benthic environment in the area appears
healthy; sediments are well-oxygenated and benthic communities are diverse.

Three types of benthic surveys are performed: benthic nutrient flux surveys, soft-bottom
surveys, and hard-bottom video surveys. Each of the three survey types is described below.

Nutrient Flux Surveys

Nutrient flux surveys are designed to measure nutrient interactions between sediments and
the water column in Boston Harbor and Massachusetts Bay. The nutrient flux surveys are
performed five times per year at seven sampling locations (Figure 8-2). Using a sediment
coring technique, vertical columns of sediment are removed and brought to the surface
intact. Each sediment core is analyzed for a set of parameters including sediment oxygen
demand, sediment nutrient flux, and sediment pore water (water contained between sedi-
ment particles) nutrients. Analysis of nutrient flux data provides information required to
assess the nutrient loading to the water column from marine sediments.

Soft Bottom Benthic Surveys

Soft bottom benthic surveys are designed to assess sediment quality and the status of the
benthic communities of Boston Harbor and Massachusetts Bay. During soft-bottom surveys,
grab samples of sediments are collected at specified locations and analyzed for apparent
redox-potential discontinuity depth, benthic infauna, and physical and chemical sediment
parameters. Three soft-bottom benthic surveys (harbor benthic, outfall nearfield benthic,
and outfall farfield benthic surveys) comprise the soft-bottom benthic studies program.

The harbor soft-bottom surveys are performed twice annually at eight stations in Boston
Harbor (Figure 8-3). These surveys are designed to measure long-term recovery in benthic
communities and sedimentary conditions at a variety of locations in Boston Harbor.
Outfall nearfield soft-bottom surveys provide baseline data on the sedimentary environ-

40 / OUTFALL MONITORING REPORT: 1994 : MWRA

ment, contaminant concentrations, and benthic infaunal communities that can be used

as a benchmark to evaluate the effects of sewage disposal from the future outfall when it
becomes operational. Nearfield benthic surveys are performed once per year with sampling
at 20 stations near the outfall site (Figure 8-4).

Farfield soft-bottom surveys provide benthic sampling data from locations throughout
Massachusetts and Cape Cod Bays (Figure 8-4}. This survey provides a farfield baseline
that may be used as reference for the nearfield stations and as true monitoring stations in
the unlikely event that the effects of the sewage discharge extend further than expected.

Hard-Bottom Surveys

A nearfield hard-bottom video survey is performed annually to supplement the nearfield
soft-bottom surveys. The hard-bottom survey provides visual information on benthic habi-
tat and organisms in rock and cobble areas near the future outfall where use of soft-bottom
survey methods is impractical. This survey is performed using a remotely operated vehicle
(ROV) equipped with a color video camera and a 35-mm camera. These surveys permit
assessment of types of topography and substrate present, populations of marine organisms,
and other evidence of biological activity. Each survey is performed along pre-specified tran-
sects, allowing for detection of year-to-year alterations (Figure 8-5).

8.4 Fish and Shellfish
Monitoring Program

The fish and shellfish monitoring program addresses potential risks to human health and
the environment arising from contamination of ecologically significant and economically
important fish and shellfish stocks. Bioaccumulation data are collected from flounder, lob-
ster, and mussel populations in Boston Harbor, Massachusetts Bay, and Cape Cod Bay.
Comparison of the data between stations and to pre-discharge data will allow evaluation of
spatial and temporal trends in the fisheries. The three biomonitoring surveys are outlined
below.

The flounder survey is designed to collect sufficient mature winter flounder to perform gen-
eral and histopathological examinations and determine bioaccumulation of priority pollutant
organics, metals, and other constituents. This survey is performed annually at five loca-
tions: the Deer Island outfall, future outfall site, Cape Cod Bay site, Broad Sound and
Nantasket Beach (Figure 4-2). All fish are collected using an otter traw! deployed by a
commercial dragger.

The lobster survey is designed to collect sufficient mature lobster specimens to provide data
on gross abnormalities and provide sufficient tissue samples for determination of physiolog-
ical condition and body burden of contaminants. Once annually, lobster are collected in 25
to 30 commercial lobster traps deployed at each of three locations: the Deer Island outfall,
future outfall site, and Cape Cod Bay site (Figure 4-2).

The mussel bioaccumulation survey obtains, deploys, and recovers blue mussels for deter-
mination of biological condition and short-term accumulation of contaminants in tissues.
Each year, mussels are deployed in replicate arrays in waters near Deer Island and in

MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1994 / 41

Massachusetts Bay near the outfall location. Mussel arrays are deployed using a subsurface
and surface buoy system.

In general, the lobster and flounder populations in Boston Harbor and Massachusetts Bay
appear healthy. Although lesions were observed on flounder in the system, tissue levels of
contaminants are well below action levels. The flounder, lobster, and mussel data provide
the MWRA with valuable baseline information. As secondary treatment is phased in, and
as effluent and water quality continues to improve in Boston Harbor and the bays, it is
anticipated that the health of fish and shellfish populations will continue to improve.

8.5 Monitoring Program Database

Since the beginning of the Outfall Monitoring Program in 1992, over 200 million pieces of
data have been generated and compiled. As the program continues, the amount of com-
piled data will grow even larger. In order to meaningfully use this large mass of data, a
coupled computerized database system and Geographical Information System (GIS) has
been developed. The coupled database/GIS system allows MWRA to store, retrieve, ana-
lyze, and display data from the monitoring program. Arc/Info is used as the GIS platform.
The database system consists of an Oracle 7 server networked to PC workstations running
MS Access. This system allows monitoring data to be entered, analyzed, and viewed simul-
taneously by several researchers working at their own computers. The database is

the source of the multi-year data analyzed by researchers in the preparation of

synthesis reports.

For the goals of the program to be met, all of the data must be of known, high quality.
Data quality is maintained through the program-wide use of rigorous Quality
Assurance/Quality Control procedures. Data from field surveys and laboratory analyses are
exhaustively checked and validated to ensure that field equipment was working properly
during surveys and that the analyses met the program’s Quality Control objectives. Only
validated data are loaded onto the centralized database.

8.6 Conclusion

Studies conducted through the MWRA Harbor and Outfall monitoring program are provid-
ing scientists with exceptional baseline scientific data. Scientific data collected during the
last few years reflect current levels of sewage treatment. As the MWRA begins discharge
through the new outfall to Massachusetts Bay and upgrades to secondary treatment of
sewage, these baseline studies will provide a sound basis for monitoring improvements in
Boston Harbor and potential changes in Massachusetts and Cape Cod Bays. As improve-
ments are made to the MWRA sewage treatment process, the extensive economic, aesthetic,
and ecological resources of this unique marine system are expected to benefit.

MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1994 / References
References

Bothner, M.H., M. Buchholtz ten Brink, C.M. Parmenter, W.M. d’Angelo, and M.W.
Doughten. 1993. The distribution of silver and other metals in sediments from
Massachusetts and Cape Cod Bays—an interim compilation. Open File Report 93-
725, United States Geological Survey, Woods Hole, MA. 33 pp.

Bousfield, E.L., 1973. Shallow-water Gammaridean Amphipoda of New England.
Cornell University Press, Ithaca and London. 312 pp.

Downey, P.C., B.D. Moffat, and G.R. Lescarbeau. 1995. Bioaccumulation of selected
organic compounds and metals in mussels deployed near Deer Island discharge
and in Massachusetts Bay, 1994. 60 pp (Tech Rep #95-9).

Durrell, G.S. 1995. Concentrations of contaminants in Dorchester Bay and Boston
Harbor sediments collected in the vicinity of CSO discharges and comparison to
1990 data. Massachusetts Water Resources Authority, Environmental Qualtiy
Department, Technical Report Series No. 95-14, Boston, MA. 128 pp.

Hillman, R.E., M.J. Moore, C.S. Peven, D.A. Lewis, L. Hansen, C.D. Hunt, and J.
Stegerman, 1994. 1993 annual fish and shellfish report. 195 pp.

Hillman, R.E. and C.S. Peven. 1995. 1994 annual fish and shellfish report. MWRA
Enviro. Quality Dept. Tech. Rpt. Series No. 95-5. Massachusetts Water Resources
Authority, Boston, MA. 82 pp.

Hunt, C.D., DE. West, and C.S. Peven. 1995. Deer Island effluent characterization
and pilot treatment plant studies: June 1993 - November 1994. MWRA Enviro.
Quality Dept. Tech. Rpt. Series No. 95-7. Massachusetts Water Resources Authority,
Boston, MA. 140 pp.

Hyman, L.H. 1959. The Invertebrates: smaller coelomate groups. (Vol V).
McGraw-Hill Book Co., Inc., New York, London, Toronto. 783 pp.

Kelly, J.R. and J. Turner. 1995, Water column monitoring in Massachusetts and
Cape Cod Bays: annual report for 1994. MWRA Enviro. Quality Dept. Tech. Rpt.
Series No. 95-17. Massachusetts Water Resources Authority, Boston, MA. 163 pp.

Linneaus Protist™ and the Linneaus Toolkit™. 1991. K. W. Estep and F. Rey. Institute of
Marine Research, Bergen, Norway and UNESCO (PROMAR) UNESCO MARINEF/84a,
Paris, November 1991.

MacDonald, D.B., J.F. Fitzgerald, and M.S. Connor. Draft Contingency Plan.
Massachusetts Water Resources Authority. 74 pp.

Moore, M.J. and J.J. Stegeman. 1993. Liver pathology of winter flounder: Boston
Harbor, Massachusetts Bay, and Cape Cod Bay—1993. 45 pp.

References (cont’d)

MWRA. 1991. Massachusetts Water Resources Authority effluent outfall monitoring
Plan phase I: baseline studies. MWRA Enviro. Quality Dept. Misc. Rpt. No. ms-2.
Massachusetts Water Resources Authority, Boston, MA. 95 pp.

MWRA. 1995. Massachusetts Water Resources Authority - Effluent Outfall Monitoring
Plan: Phase lJ Post Discharge Monitoring (Draft). MWRA Enviro. Quality Dept.
Massachusetts Water Resources Authority, Boston, MA.

Shea, D. 1993. Annual review of toxic contaminants discharged by MWRA: 1993.
68 pp. +appendices.

Smith, R.I. (ed.), 1964. Keys to marine invertebrates of the Woods Hole region.
Contribution No. 11. Systematics-Ecology Program, Marine Biological Laboratory,
Woods Hole, MA. 208 pp.

USGS Web Site. http:\\vineyard.er.usgs.gov\arc\data\seafloor.gif

Watling, L., 1979. Marine Flora and Fauna of the Northeastern United States, Crustacea:
Cumacea. NOAA Technical Report NMFS Circular 423:1-23.

Weiss, H.M., 1995. Marine animals of Southern New England and New York. State
Geological and Natural History Survey of Connecticut, Department of Environmental
Protection.

Wilson, E.B., 1881. The origin and the significance of the metamorphosis of Actinotrocha.
Quarterly Journal of Microscopical Science, New Series. 21:202-218.

Acronym Summary

BOD _ biochemical oxygen demand nBOD _ nitrogenous biochemical
cBOD carbonaceous biochemical oxygen oxygen demand
demand NOEC no observable effect concentration
CHV centrotubular hydropic vacuolation, NPDES National Pollutant Discharge
a fish liver lesion Elimination System
DIN _ dissolved inorganic nitrogen PAHs polyaromatic hydrocarbons
DO dissolved oxygen PCBs polychlorinated biphenyls
ERL NOAA low effects range values for ppb _ parts per billion
sediment, rarely associated with ppm __ parts per million
toxic effects RPD redox potential discontinuity

ER-M NOAA median effects range values, TSS total suspended solids
often associated with toxic effects

LC50 concentration for 50% lethality of
bioassay test organisms