LANDFILL EVALUATION STUDY
FOR THE
CONNECTICUT DEPARTMENT OF
ENVIRONMENTAL PROTECTION
ON THE
TOWN OF WATERTOWN SANITARY LANDFILL
WATERTOWN, CONNECTICUT
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 1
JOHN F. KENNEDY FEDERAL BUILDING • BOSTON, MA. 02203
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LANDFILL EVALUATION STUDY
FOR THE
CONNECTICUT DEPARTMENT OF
ENVIRONMENTAL PROTECTION
ON THE
TOWN OF WATERTOWN SANITARY LANDFILL
WATERTOWN, CONNECTICUT
TECHNICAL ASSISTANCE PANELS PROGRAM
DIRECTIVE OF WORK #12
CONTRACT No. 68-01-4940
PREPARED FOR:
REGION I
U. S. ENVIRONMENTAL PROTECTION AGENCY
WASTE MANAGEMENT BRANCH
JOHN F. KENNEDY FEDERAL BUILDING
BOSTON, MASSACHUSETTS 02203
PREPARED BY:
WEHRAN ENGINEERING CORPORATION
666 EAST MAIN STREET
MIDDLETOWN, NEW YORK 10940
MARCH, 1980
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Public Law 94-580 - October 21, 1976
RESOURCE RECOVERY AND CONSERVATION PANELS
SEC. 2003 - The Administrator shall provide teams of personnel, including
Federal, State, and local employees or contractors (hereinafter referred to
as “Resource Conservation and Recovery Panels”) to provide Federal, State
and local governments upon request with technical assistance on solid waste
management, resource recovery, and resource conservation. Such teams
shall include technical, marketing, financial, and institutional specialists,
and the services of such teams shall be provided without charge to States
or local governments.
This report has been reviewed by the Region I EPA Technical Assistance Project
Officer, and approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental Protection Agency,
nor does mention of trade names or commercial products constitute endorsement
or recommendation for use.
EPA Region I Project Managers: Conrad 0. Desrosiers
Dennis G. Gagne
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TABLE OF CONTENTS
PAGE NO .
FOREWORD
INTRODUCTION AND SUMMARY
BACKGROUND 1
PRESENT ENVIRONMENTAL IMPACTS 3
Leachate Characteristics 3
1. Landfill Stabilization 5
2. Ground—Water Dilution 5
3. Sediment Basin Renovation 5
Surface Water 7
Ground Water ii
Methane Gas 12
Summary 12
ALTERNATIVE ENVIRONMENTAL MANAGEMENT APPROACHES 14
Leachate 14
1. Production 14
2. Collection 17
3. Treatiient 18
Methane Gas 21
1. Production 21
2. Migration 22
3. Control Mechanisms 23
(a) Passive Systems 23
(b) Active Systems 24
RECOMMENDED ENVIRONMENTAL MANAGEMENT APPROACHES 26
Leachate 26
1. Production 26
2. Collection 26
3. Treathient 27
Methane Gas 28
SITE EXPANSION AND FINAL USE 30
COSTS 32
BIBLIOGRAPHY
APPENDIX
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LIST OF FIGURES
PAGE NO .
FIgure 1: F—i
Figure 2: F—2
Figure 3: F—3
Figure 4: F—4
Figure 5: F—5
Figure 6: F—6
Figure 7: F—7
LIST OF TABLES
PAGE NO .
Table 1: ComparIson of Characteristics of Watertown
Landfill Leachate and Domestic Sewage 4
Table 2: Comparison of Water Quality at Weirs #1 and #2 7
Table 3: A Comparison of Water Samples Collected by
P. Perlsweig on May 31, 1978 8
Table 4: Comparison of Size and Flow of Watertown
and Brookhaven Marsh Treatment Systems
Site Location Map and photographs
Remedial Action Plan
Level Spreader
Methane Gas Monitoring Well
Drainage Swale
Drainage Swale with Erosion Control
Methane Gas Pressure Relief Vent
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FORE R 0
Wehran Engineering wishes to acknowledge the Study and Report —
Part II B prepared by Roald Haestad, Inc., of Middlebury, Connecticut,
which was used as a source of information for the preparation of this
study. Wehran Engineering also wishes to acknowledge the assistance of
Mr. William B. Owen, P.E., Watertown Municipal Engineer, and Mr. Paul W.
Perlsweig, P.E.,, Senior Sanitary Engineer, Connecticut Department of
Envi romental Protection.
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INTRODUCTION AND SUMMARY
Many landfills throughout the United States, like the one in
Watertown, Connecticut, were started years ago without any knowledge of
the potential problems that leachate and methane gas migration could
produce. The objective of this study is to investigate what, If any,
Impacts the Watertown Landfill is having upon the environment.
This study was limited to the amount of data available concerning
the landfill. One source of information regarding this site was
contained in a report completed by Roald Haestad, Inc., a local
engineering consulting firm. One field visit and various conversations
with the local municipal engineer and Connecticut Deparbnent of
Environmental Protection Landfill inspector were additional data
sources. Our review of all the data did not Indicate that any highly
significant environmental impacts are occurring due to this landfill.
Any impact on the environment from leachate migration is minimized
by Its on—site dilution and attenuation by an adjacent wetland area.
Our recommendation regarding the leachate migration would be to increase
the contact area of the leachate flow to the wetland area located
between the sediment basin and Artillery Road. To accomplish this
objective, we are proposing that a level spreader be constructed right
after the leachate flows out of the basin. The success of a marsh/pond
system on treating sewage sludge In Upton, New York, Indicates to us
that the wetland appears to be adequately attenuating the present
diluted leachate flow. We have also recommended that a rigorous water
quality program commence. This data would be used to monitor any future
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impacts the leachate may have. It would also allow for adequate warning
time to implenent a new control strategy so as to prevent Irreparable
damage from occurring to the marsh from changes in the leachate quantity
and quality.
No analytical data on methane gas has been collected. Our field
investigation revealed that the vertical migration of the generated gas
may be causing the sparse grass cover on the existing landfill. We do
not feel, however, that horizontal gas migration Is a problem here. We
have recommended that a gas monitoring program be started.
We believe all our recommendations are reasoaable responses to the
impacts which currently exist at this facility. We believe that these
recommendations will lessen any existing impacts and discover any new
Impacts.
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Background
The Watertown landfill has been in operation for approximately 40
years at Its current location. The landfill has therefore undergone
changes from being operated as an open burning dump to a sanitary
iandf ill. The site consists of two distinct but contiguous parts.
The older closed portion rises to elevations of approximately 757 feet,
containing approximately 75 feet of solid waste. It is estimated that
the bottom third of the landfill Is composed primarily of partially
burned solid waste due to the prior open burning history of the
landfill.
As the state—of-the—art technology for sanitary landf filing has
improved, so have the operations of the Watertown landfill. The
Watertown landfill operation ceased open burning in the late 1960’s and
purchased a landfill compactor around 1972. The continual problem of
leachate migrating from the landfill into an adjacent marsh was finally
addressed In the mid 1970’s by the Connecticut DEP and corrective
actions were so ordered. The corrective actions Included improvements
to surface water drainage, construction of a sedimentation basin, and
the channeling of leachate flow to the sedimentation basin.
These latter improvements directed the majority of leachate flows
to a marsh south of the landfill and thence into Lake Winnemaug. These
developments received much attention and study, the latter detailed In a
report prepared by Roald Haestad, Inc. Part II B. That report (1977)
included results of efforts to trace pollutants through the swamp.
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Samples were taken of the discharge from the sedimentation basin
approximately 200 feet downstream and at the end of the swamp. Dye
tracer studies were also undertaken. Both efforts failed to show
migration of pollutants through the marsh. Other limited infonuation
does not Indicate any significant detrimental effects on the marsh.
Any changes In vegetative species have not been Investigated.
Hydrogeologically, the landfill Is apparently situated In a ground—water
divide In a ground—water discharge zone. Previous studies by Roald
Haestad, Inc. indicate that the solid waste Is in direct contact with
the ground water. The fact that this facility Is located in a
discharge zone Is perhaps fortunate, in that this hydrogeologic
condition prevents contami nation of ground—water resources.
The purpose of this report Is to evaluate the effect this landfill
is having upon Its surrounding enviromient and to recommend appropriate
technical solutions. Specifically, what damage, if any, has the
landfill’s leachate done to the adjacent marsh. In addition, this
report will discuss the landfill’s Influence upon ground-water quality
and the possibility of methane gas migrating into neighboring lands.
This report will review the available technical solutions to these
problems and then recommends the solutions which are the most
appropriate for this facility.
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PRESENT ENVIRONMENTAL IMPACTS
The object In any assessment of managing a potential source of
pollutants and its effects upon the environment is to prevent or to
minimize the degradation of the environment. The focal point Is the
control of a pollutant’s impact on the environment and not necessarily
the total prevention of its discharge to the environment. The
following sections evaluate what, if any, impacts the landfill’s
leachate and methane gas have had upon the surrounding environment based
on available data and on site inspections.
L eachate Characteri sti cs
To fully appreciate and understand the impact of the generated
leachate upon the surrounding ground and surface waters, we must first
review what its particular characteristics are at this site.
Leachate seeps out of the old tier and existing fill area and flows
overland into the drainage ditches and eventually Into the sediment
basin. The constant flow of ground water through the landfill
eventually emerges as leachate and it, too, flows into the basin. The
discharge from this basin is measured at weir #1. Therefore, we will
use welr #1 as our environmental starting point. The water quality at
weir #1 was analyzed from a sample collected on May 31, 1978, by Mr.
Paul Perlsweig. This data Is compared to domestic sewage to enable the
reader to obtain a better perspective on how potentially harmful this
leachate may be. (See Table #1).
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TABLE 1
Comparison of Characteristics of Watertown Landfill
Effluent and Domestic Sewage
CONCENTRATION 1
CONSTITUENT
Effluent From
Sediment
Basin 2
Leachate
From
Landfill
Six months
old 3
Typical
Domestjc
Sewage’
Ratio of
Effluent:
Sewage
Alkalinity as CaCO
500.0
3100
100.0
5.0
Biochemical Oxygen Demand
13.0
10000
200.0
0.065
Chemical Oxygen Demand
110.0
17500
500.0
0.22
Chlorides
210.0
660
50.0
4.2
pH
6.7
5.5
8.0
Iron
83.0
55
0.1
830.0
Total Suspended Solids
150.0
360
200.0
0.75
1. Mg/l except for pH (pH Units)
2. Connecticut State Department of Health, from sample
collected P. Perlsweig on May 31, 1978, from Weir #1.
3. Boone County Research Facility - Cell No. 1, Samples
taken January 10 and 24, 1972.
4. Metcalf and Eddy, Inc., Wastewater Engineering: Collection, Treatment
and Dis osa1 . McGraw-Hill Book Company, New York 1972.
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The landfill effluent concentrations are relatively low when
compared to sewage. The dilute character of the leachate is probably
due to a combination of the following factors: landfill refuse
stabilization, ground—water dilution, some renovation of the leachate as
It flows overland to the sediment basin, and some equalization within
the sediment basin. Available water quality data does not allow for
separation of the effectiveness of each of the various factors. A
general discussion of the role of each of these factors is presented in
the following paragraphs.
1. Landfill Stabilization
This landfill has been in operation for approximately forty years.
It has passed through the stages of an area where garbage was burned to
an open dump to a sanitary landfill. The amount of solid waste which
is deposited here is approximately seventy-five (75) feet in depth.
Rainfall must pass through new garbage and then through old garbage
before ft comes In contact with the ground water and then emerges as
leachate. There Is a general lack of knowledge of how a landfill’s
Internal biological and chemical reactions over time. However, one
possible effect of an old landfill upon leachate--qual-Ity--would- be-to—
dampen Its strength. The older garbage would have been decomposed into
Its basic elemental forms devoid of leachable material. As the newly
formed leachate percolates through the older garbage, It would react
chemically and biologically and some contaminants from the leachate
would be attenuated by the older garbage. The primary mechanism most
likely active here would be adsorption by residual organic matter and
Incorporation by the biomass. Such attenuation should be stable in that
factors which would tend to eliminate the blomass are highly limited.
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2. Ground—Water Dilution
The Roald Haestad report dated June, 1977, (p.17) states that,
after the landfill rehabilitation effort was completed, no changes In
the ground-water table were observed. He theorizes that the ground
water enters at the base of the refuse, flows through the refuse, and
emerges as leachate. A site Inspection on October 4, 1979 by Wehran
Engineering personnel confirms this observation. This constant flow of
ground water has diluted the leachate so that Its strength is weakened
and may have also reduced the rates of pollutant solubilizatlon. The
effectiveness of these “reactions” Is evidenced by the lack of high
pollutants concentrations as measured at weir #1.
3. Sediment Basin Renovation -
Leachate seeps out of various locations throughout the landfill. As
the leachate flows overland to the sediment basin, some biological
and/or chemical pretreatment may be active. As It reaches the basin,
the leachate becomes diluted with the surface water run—off and
groundwater discharge. The sediment basin slowly releases the diluted
leachate Into the marsh. The only apparent treabnent that the basin
provides would be to simply settle out any of the larger silt particles
and to provide retention time to prevent high concentrations of leachate
from entering the marsh. A grab sample collected on April 21, 1978, by
Mr. R. Smith, indlcstes low strength pollutants - a pH of 6.6 and a BOD 5
of 78 ppm. The iron concentration (41 ppm), total (766 ppm) and fixed
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solids (708), and chlorides (190), are low strength. Mr. Perlsweig
collected a sample from this basin on May 31, 1978. This analysis
compares more or less with Mr. Smith’s.
Surface Water
The water which enters the marsh from wefr #1 Is of relatively low
strength when compared to other leachates. Perlsweig collected a sample
on May 31, 1978, from weir #1 which is located between the basin and the
swamp, and welr #2, which is located in the marsh which measures flow
from welr #1 and diverted stream flow. Weir #2 is approximately 200
feet down-gradient from weir #1. A quick comparison of selected
parameters shows the influence that the first section of marsh is having
on the leachate.
TABLE 2
Comparison of Water Quality at Weirs #1 and #2
Parameter Wet r #1 Weir #2
pH 6.7 7.1
BOO 5 13.0 ppm 3.2 ppm
COO 110.0 “ 34.0
ChlorIdes 210.0 “ 70.0
Iron 83.0 “ 22.0
It should be noted here that none of the analytical data of the
collected water samples Involved an Investigation for toxic pollutants.
At this time, the presence of any toxic pollutants existing tn this
leachate Is unknown. The marsh shows an ability to render some
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attenuation to an already low strength leachate, in spite of the fact
that its flow is primarily restricted to a small stream channel which
bisects the marsh. This channel minimizes leachate contact with the
marsh and therefore limits the area affecting treatnent.
Perlsweig collected a sample of the stream which originates in the
marsh and flows into Lake Winnemaug. The sample was collected at wefr
#3 just before the stream discharges into the lake. A comparison of all
three (3) water samples collected by Perlsweig indicates attenuation of
leachate contaminants by the marsh. Since flow data is unavailable, no
quantification of pollutant removal is possible at this time.
TABLE 3
A Comparison of Water Samples Collected by
P. Perlswelg on May 31, 1978
Parameter Weir #1 WeIr #2 Weir #3
pH 6.7 7.1 7.2
BOD 5 13.0 ppm 3.2 ppm 2.5 ppm
COD 110.0 ppm 34.0 ppm 50.0 ppm
Chlorides 210.0 ppm 70.0 ppm 34.0 ppm
Iron 83.0 ppm 22.0 ppm 3.3 ppm
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Between weirs #2 and #3 another source of pollution exists. Many
former summer residences constructed near the lake are now being
utilized year—round. These homes are serviced by septic tanks. Reports
of septic tank failures were not available to assess their impact upon
water quality. It can only be surmised that each year a number of these
tanks and/or leach fields “fail” from over use. A portion of this
effluent from these “faIlures ’ could migrate downgradient, flow into the
marsh, past weir #3 and Into the lake. The increase in the chemical
oxygen demand (COD) between weir #2 and #3 could possibly be due to this
effluent. It is not inconceivable that this effluent is Increasing the
COD while not Increasing the 5—day biochemical oxygen demand (BOO 5 ).
Organic or inorganic chemicals deposited into the tanks may be the
source of this increased chemical activity. For example, homeowners may
have deposited large amounts of copper sulfate Into the tanks so as to
clear their leach fields of tree roots.
Regardless of other sources of potential pollution, contaminant
concentrations are reduced as you progress through the marsh to Its
discharge to Lake Winnemaug.
A marsh’s ability to absorb the hydraulic and solids loading from a
pollution source has had documented success. A marsh was created to
treat a landfill’s leachate at a private landfill In Barre,
Massachusetts. This marsh achieved a reduction In BOO 5 of leachate from
20,000 mg/i to less than 10 mg/i. The closest example to the basi n-
marsh treabnent configuration Is a prototype experimental marsh/pond
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operation utilized at Brookhaven National Laboratory in Upton, New York.
Brookhaven operates a 10,000 gal lon per day sewage treatment system that
consists only of a marsh and a pond. The following is a brief
comparison between the Brookhaven and Watertown marshes.
TABLE 4
Comparison of Size and Flow of Watertown and Brookh ven
Marsh Treatment Systems
Brookhaven Watertown
Size .4 acre 2 to 3 (active contact) acres**
Flow 50,000 gals/acre/day 4800 gals/acre/day*
*Note p. 12 Haestad reports, leachate flows between 10—15 gpm after
rehabilitation.
Note p. 54 Haestad
The effluent from the marsh/pond tn the Brookhaven system nearly
complies with the discharge standards specified by the United States
Environmental Protection Agency and the United States Public Health
Service. The experimental data collected at Brookhaven lends credence
and meaning to the Watertown results. It should be noted that the
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Watertown marsh acreage does not include those portions across Artillery
Road and Hamilton Lane. These additional contact acres will only
further reduce the effluent’s strength.
Ground Water
The Connecticut Departhient of Health’s analytical findings of the
ground-water wells in and around the landfill are fairly consistent. Plo
indication of leachate contamination of these wells is evident.
Occasionally some of the wells along Artillery Road and Hamilton Avenue
had moderate sodium and chloride readings. The source of these could be
home water softeners or road de—icing salts. The pH readings were
consistently around 6.0. This could be attributable to the natural
soils surrounding the landfill. A ground—water well was constructed
through the landfill next to the dog pound. Available analysis 0 f this
water indicates that it Is potable.
The flow of ground water in this area is Into, through and out of
the landfill. The ground water emerges as contaminated surface water.
It Is, therefore, unlikely that any contamination of the ground water
adjacent to this site Is occurring at this time. High ground—water
withdrawal rates such as by a future Industrial or municipal well, could
however, reverse this situation resulting in possible contamination of
g ound—water resources.
Seven (7) ground—water monitoring wells have been installed around
the landfill but, to date, no ground—water quality data has been
obtained. The limited amount of ground—water data does not allow for
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much discussion of ground-water pollution. We recommend that a ground-
water monitoring program be implemented to detect possible future
changes in quality.
Methane
A methane gas monitoring program has not been undertaken at this
facility or In the adjacent property. The final cover material placed
on the upper tier landfill consists of a gravelly soil and probably
allows most of the gas to be vented vertically, rather than encouraging
horizontal migration. No venting system other than the ground—water
monitoring well located In the middle of the landfill Is present at this
site. No destruction of plant life on adjacent lands which may occur
due to gas migration was observed during site inspections. However, a
poor vegetation cover was observed on the completed section of the
landfill (upper tier). This sparse vegetation may be due, in part, to
the vertical movement of gas through the cover soil, as well as poor
soil conditions.
Summary
We believe that the Impact of leachate migration from this landfill
Into surrounding ground waters Is relatively Insignificant. We have been
unable to discover any specific evidence of contamination of any of the
private wells in the homes located in the landfill vicinity. Also,
based upon the limited data we have been unable to find specific
evidence of degradation of the adjacent marsh 1 . The analysis of. the
diluted leachate at Weir #1 (See Table #1) for those selected parameters
reveals a low strength effluent. The biochemical oxygen demand is very
(1) No biological or chemical analysis has been completed on virgin
areas of the marsh to allow for a rigorous comparison.
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low and the chemical oxygen demand is moderate. Therefore, even before
the leachate leaves the sediment basin, its strength is very weak and it
Is not surprising to find that the marsh has not been severely impacted.
Our conclusions regarding the impact of methane gas are based upon
a visual inspection of the landfill and the surrounding area. We
believe that the gas is most probably vented vertically through the
landfill cover soil. Therefore, we believe no immediate danger to any
surrounding area due to gas migration exists. Methane gas, however, may
be a major cause of the sparse and poor quality vegetative growth upon
the completed landfill area.
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ALTERNATIVE ENVIRONMENTAL MANAGEMENT APPROACHES
Before a leachate or a methane gas management system can be
selected for this site, a review of the available technology is
necessary. This section reviews what Is currently being utilized In the
field of solid waste management in these o areas. The ultimate
selection of a system can only be completed by comparing each systems’
costs and capabilities to the specific site characteristics and the
severity of existing environmental problems.
Leachate
Every landfill produces leachate at various quantities and potency
depending upon numerous characteristic factors of that particular
landfill. The migration of leachate from a landfill to adjacent ground
and surface waters has been harmful In many instances. An understanding
of how leachate Is produced, collected, and treated Is needed before a
leachate management system can be selected for this facility.
1. Production
Leachate is formed when water has been in contact with solid waste
and contains dissolved or suspended materials from that solid waste —
the quantity and composition of leachate varies with the characteristics
of the waste, the particular site, and with time.
Leachate generation may best be understood wi th reference to a
landfill with a refuse layer over which a final cover of clean soil has
been applied. Precipitation falls onto the site where a portion, the
“run—off”, flows over and along the surface to drain away from the site
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and where the remainder infiltrates down into the soil cover.
Evapotranspiration (evaporation from the soil and transpiration from
plants) removed moisture from the active soil layer and returns it to
the atmosphere. Once this soil layer reaches field capacity, any excess
water will produce percolation downward into the underlying refuse
layers.
The refuse will act as a sponge, initially absorbing the
percolating water and finally reaching field capacity. Run—off and
evapotranspiration essentially affect only the active soil layer, which
is subject to environmental conditions. Moisture from the refuse layer
Is removed primarily by diffusing gases, and this amount is very small.
Consequently, once the refuse layer reaches field capacity, it remains
at field capacity, and any entering percolation produces and equal
amount of leachate. The anaology to a sponge is still applicable — once
a sponge reaches field capacity, any additional water will cause an
equal release of water from the bottom or sides.
Some small quantity of leachate may be produced in advance of the
refuse layer’s reaching field capacity. Because solid waste is not
uniform fri composition, channeling may occur or, as percolation seeps
through the refuse an advance wetting front may form. Both of these
factors contribute to “early” leachate production. -
Numerous studies Indicate that most of the factors affecting
leachate generation are highly site specific. Factors such as
precipitation, evapotranspiration, and soil permeability at a particular
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site figure prominently in determining the potential for surface and
ground—water infiltration and eventual leachate generation.
There are two different schools of thought regarding the management
of surface and ground—water Infiltration into a landfill and eventual
leachate generation. One strategy to minimize the amount of generated
leachate Is to minimize the amount of water entering a landfill. The
other stragegy Is just the opposite. It encourages the flow of both
surface and ground waters through a landfill. By having a constant flow
of water through a landfill, a leachate of low concentration Is always
produced and the overall impact of this diluted flow is thereby
ml nimized.
Another water—leachate management philosophy close in theory to the
second strategy regards the rate of pollutant’s solubilization within a
landfill. If one believes that the rate of pollutants’ solubilization
is constant over a period of time, the quality (concentration) of
pollutants released is inverse to the quantity of leachate produced.
Less volume of leachate would produce a higher pollutant level under the
first strategy. More volume of leachate would produce a lower pollutant
level under the second system. In either case, the same total poundage
of pollutants is assumed to be released into the environment but the
effects of their release are dramatically different.
The selection of a water-i eachate management system for this site
depends upon what final treatment scheme is chosen. If a treatment
scheme like recfrcuiation, spray irrigation or wastewater treatment Is
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selected, one would want to minimize the volume of leachate to be
treated. This management scheme corresponds to strategy Number 1.
Since groundwater flow is the largest source of water entering into this
landfill, a diversion trench or cut-off wall would have to be
constructed. An extensive hydrogeologic investigation would have to be
completed in order to obtain the necessary soil profiles and depths and
volumes of flow before an effective diversion system could be designed.
The practicality of diverting the groundwater flow is very questionable
since the landfill Is in a discharge area and the volume of water to be
managed would, most probably, be tremendous.
If the existing marsh is to be solely utilized for treathient, one
would want to mix as much surface and ground water with the leachate in
the sediment basin as possible. This management scheme corresponds to
strategy Number 2. In essence, management of water at the landfill
would be designed so as to maintain the current quantity of leachate
being formed. The current day—to—day landfilling operation and soil
cover type should be preserved.
2. Collection
Most newly designed sanitary landfills are required to have a
leachate collection system utilizing some sort of highly Impermeable
liner and a piping network. The selection of a specific liner depends
upon the expected groundwater pressures, economics etc. The liner is
normally placed down prior to the beginning of the disposal operation.
However, this landfill is existing, the placement of a liner here Is not
feasible. The expense of excavating the already in—place solid waste,
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installing a liner, and a collection system, and placing back the solid
waste would be an impractical and expensive undertaking.
The installation of a conventional leachate collection piping
system at this site would also require the excavation and redeposition
of considerable portions of the in—place solid waste. An alternative
collection system, if required, would have to be selected. This
alternate system would probably consist of a toe—of-slope collection
pipe to intercept leachate outcrops. This system would be constructed
around the entire down—gradient slope of the landfill. The construction
of this collection system would effectively be only a modification of
the existing ditches. We do not recommend that this alternative system
be constructed since the existing ditches can be Improved easily enough
to adequately collect and drain the leachate to the sediment basin. The
construction of a piping system would be considerably more expensive and
not that much more efficient.
3. Treatment
Once leachate has been collected It must be satisfactorily treated
before it can be released Into the surrounding environment. Since the
requirements for designing a sanitary landfill are relatively recent,
very little experience in treating leachate has been obtained. Typical
leachate treatment systems Include recirculation, spray Irrigation,
disposing of the leachate In an existing wasthvater treatment facility
or constructing an on—site treatment system.
Recirculation of leachate involves the pumping of collected
leachate back into a landfill, usually directly into the active face.
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Test results of this treatment method indicate that a rapid
stabilization of the landfill and leachate occurs, because of rhe
accelerated growth of anaerobic bacteria within the fill. Since
biological stabilization of the organic part of the refuse would proceed
at an optimal rate, biochemical oxygen demand, chemical oxygen demand
and total organic carbon levels in the leachate In these landfills which
used recirculation were reduced. Much research must still be completed
on the effectiveness of this method. Critics claim that it does little
or no real removal of pollutants and that it cannot be used in times of
heavy rainfall or when the solid waste and ground are frozen. Further
once the landfill is completed, the generated leachate within the
landfill must still be removed and treated. We do not feel it is
warranted to implement this system at Watertown because of the
likelihood of the existence of a high groundwater mound within the
landfill. This phenomenon Is causing more leachate generation than can
be handled by recirculatlon. Further, leachate recirculatlon is most
effective in an ongoing landfill and since this landfill has a limited
life, the expense of constructing a recIrculatlon system here is of
questionable value.
The spray irrigation of leachate relies upon the evapotranspiration
characteristics of the landfill locale. Depending on the
transmissibility, grass grown on the landfill cover, the moisture
storage capacity of the cover, and the evaporation factor of the sun and
wind In the site’s area, this method can reduce leachate volumes. The
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volume of leachate which can be handled in general is in the vicinity of
one to two Inches per acre per week (precise application rates can not
be determined initially). Overloading of the available spray area will
contaminate the cover soil. Therefore, the loading rates must be
monitored to prevent the cover from being overtaxed and rendering Its
attenuative properties useless. Odors are a major potential problem with
this method of treatment. We do not feel this method is applicable here
because of the landfill’s limited life. Further, spray irrigation is of
seasonal utility, whereas Watertown’s landfill leachate generation is
year—round. The expense of purchasing the necessary equipment would not,
in our opinion, be justified.
Using an existing s erage treatment facility or constructing a
physical/chemical/biological treatment system are quite elaborate and
expensive undertakings. Because of leachate’s transient strength and
flow characteristics, the technology of formalized treatment Is still
being developed. The treatment process which entails the sequence of
lime precipitation/clarification/air strlpplng/neutralization/
phosphorous addition/activated sludge appears to provide the best
treatment to date. The problem with utilizing an existing
wastewater treatment plant is that a great dilution of the
leachate must be accomplished to prevent disruption of the system.
Preliminary work in this area indicates that a sewage treatment plant
would need a present sewage flow one hundred times the anticipated
leachate flow. A 1.4 rngd treatment plant would be required to accept
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the daily leachate flow generated at this site. The cost of
transporting the leachate would probably make this alternative
unacceptable.
The use of a marsh as a treatment system in attenuating wastewater
and leachate has had documented success. This report has already
mentioned the experimental work completed in Brookhaven on sewage and in
Barre, Massachusetts on leachate. Additional work must still be
completed on the long—term utilization of marshes to treat pollutants.
The marsh treatment system, however, is both energy-saving and
inexpensive, making it particularly attractive for small municipalities
like Watertown.
Methane Gas
The gases produced by the biological degradation of deposited solid
waste in a landfill can pose serious difficulties If not controlled.
Methane, when ignited, can explode when it reaches a concentration of 5
to 15 percent with air. Confined spaces like basements or homes are
likely candidates for gas accumulation and possible explosion hazard.
Another potential problem associated with methane Is that It displaces
oxygen in the soil which Is required by the root system of plants and
can cause extensive damage to vegetation growing on lands adjacent to a
landfill, as well as the landfill cover vegetation.
1. Production
The production of methane Is a result of the decomposition of the
organic material by microorganisms. Initial gas formation consists of
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carbon dioxide with some hydrogen sulfide and ammonia. It is when the
biological activity depletes the oxygen supply and becomes anaerobic
that methane becomes the major decomposition gas. While the production
of methane is a very common process, it Is somewhat delicate and easily
upset. As long as sufficient moisture Is available within a landfill,
decomposition gas will be formed since most microorganisms are active In
the presence of moisture.
Other factors which affect gas production Include the organic
content of the solid waste, particle size and degree of compaction of
the solid waste, placement and type of cover, landfill topography,
landfill hydrogeology etc. Theoretically, a pound of refuse can produce
2.7 cubic feet of carbon dioxide and 3.9 cubic feet of methane. How
much of this potential production will be realized In a particular
landfill over a given period of time will depend on a combination of the
above factors which aid or hinder gas production.
2. Migration
At some sanitary landfills, methane gas has been reportedly found
In explosive concentrations as far away as six hundred feet. Critical
areas of a landfill In terms of its gas migration potential would
Include the following:
(1) Depth of the landfill and/or water table below the ground
surface.
(2) Gas pressure within the landfill.
(3) Permeability of the landfill cover soil.
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(4) Permeability of the soil surrounding the landfill.
When the cover soil is of low permeability vis—a—vis the soil
surrounding the landfill, lateral gas migration would tend to occur.
One possible influence upon the gas migration could be excessive
precipitation. Rainwater would saturate the soil cover and fill the
soil pores. The gases vertical escape would be blocked and a pressure
buildup would then occur within the landfill forcing the gas to travel
laterally. Eventually, the rainwater would be evaporated or be
transpirated away reopening the pore spaces for vertical gas migration.
3. Control Mechanisms
As we have already discussed, uncontrolled migration of gases from
a landfill can pose a threat to the surrounding environs. Specifically,
damaging vegetation or creating a hazard of gas explosion. The purpose
of any control system would be to insure that all the gases are vented
safely into the atmosphere. Gas control systems can be grouped into two
major categories: passive or active systems.
(a) Passive Systems
There are various systems currently used today which are
relatively free from maintenance after their Installation.
These systems are known collectively as passive gas venting
systems. Some examples of these methods include the use of
gravel—filled vents or gravel—filled trenches which would be
located at the landfill circumference to provide a more
permeable path for the escape of the gas from the landfill
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into the atmosphere. These methods allow for the
decomposition gases to be intercepted and prevented from
migrating beyond the landfill limits.
The long—term effectiveness of either of these o (2)
systems is suspect. The vents only Intercept the gas which
flows directly into the pipe. Much of the landfill gas flow
would bisect these vents and migrate off—site. The pipes are
also very attractive to vandals. The gravel—filled trenches
are easily covered over by vegetation and rendered useless.
Another passive system consists of utilizing a clay or
some synthetic material to construct a barrier to prevent the
gas from migrating beyond the landfill circumference. A
venting system is usually utilized along with this system in
order to prevent the buildup of positive gas pressure on the
interior face of the barrier. The construction costs of this
system make It practical only where a definite gas migration
problem exists. We do not believe it Is required at this
fac Ill ty.
(b) Active Systems
The active systems utilized to prevent gas migration
generally consist of vertical riser pipes placed around a
landfill perimeter, all connected to a header pipe which In
turn is connected to an exhaust blower. This type of system
has been used where the natural ventilation of the riser pipes
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did not provide an effective barrier to gas migration. This
basic system has been modified to include an induced draft
vapor fume Incinerator that uses the gas as a fuel. This
system may have potential at this facility. The proximity of
the dog pound to the landfill makes the recovery of the
methane gas a possibility. The recovered gas could be used to
supplement the pound’s present heating system. The
feasibility of utilizing the gas in this manner would require
further investigation.
At present, there appears no great potential for methane gas
migration from this landfill to adjacent land. The ground—water table
as depicted on Figure 8 of the Haestad Report should prevent any gas
from travelling through the underlying soils. The presence of the
sparse veqetatlon growth on the upper tier may be due to the gas
displacing oxygen required by the plants’ root system.
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RECOMMENDED ENVIRONMENTAL MANAGEMENT APPROACHES
Presently, we find no evidence to indicate that significant
enviromiental degradation is being caused by the operation of this
facility. The leachate which migrates from this facility Is not highly
contaminated and, based upon the limited analytical data, appears to
receive a fair degree of attenuation by the marsh. The possibility of
contamination of a major ground—water resource is unlikely since this
site is in a discharge area. No methane gas data is available but the
possibility of lateral gas migration from landfill appears to be
unlikely although some adverse effect on cover soil vegetation may be
occurring.
L.eachate
Based upon the experimental data from Brookhaven and the comparison
chart previously presented, it appears the disposal operation and
leachate migration can continue at Its present level with no change in
impact to the marsh. However, a monitoring program and modification of
the leachate flow pattern are recommended.
1. Production
The daily landfllling procedure of having the smallest possible
active face and applying daily cover should be continued. The present
amount of soil cover used is sufficient. No change in the soil type
appears to be warranted. When the present portion of the landfill is
completed, the entire landfill area should be limed, fertilized and
seeded to prevent soil erosion.
2. Collection
As much as possible, all leachate seeps, surface water run-off and
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groundwater discharges should be channeled into the sedminentation
basin. The mixing of all these flows in the basin will dilute the
pollutants concentration and lessen its impact upon the marsh. To
accomplish this goal of maximum leachate dilution, we are recommending
that the surface water drainage swale which exists along the landfill’s
westerly border be extended to service the entire southerly border and
be terminated at the sedimentation basin. The extension of this swale
will Intercept surface run—off and leachate seeps which currently flows
in this southern area. Figures 5 and 6 located in the Appendix are
recommended typical drainage swales cross-sections. Where mild sloping
land exists, the unlined swale can be used. Where the drainage swale
descends steep slopes (>5%) erosion protection with stone has been
included. The final system design should carefully consider the surface
drainage peak flows to avoid possible overloading of the sedimentation
basin and subsequent flushing out of contaminants during precipitation
events.
3. Treatment
No change (n the role of the marsh as the treatment system of this
site Is anticipated. The cost to the town is negligible and the choice
of another treatment system would most probably not be so much superior
to the marsh’s attenuative ability. One possible change which should be
implemented would be to spread the flow of the diluted leachate to a
greater surface area of the marsh. This could be accomplished by
constructing a level spreader perpendicular to the main channel flow.
This spreader would be constructed right after the flow passes weir #1,
utilizing the existing semi-wetland area. This wetland area would
eventually be converted into a marsh. Another spreader could be
constructed after Artillery Road if deemed necessary. (See Figure 2).
We also recommend that a monitoring program of the leachate flow
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and of the marsh itself should be continued. This monitoring data will
enable one to spot any deterioration trends within the marsh and to
allow modification of the leachate flow to prevent any permanent damage
to the marsh. This monitoring program should include the analysis for
the following parameters:
Arsenic ABS/LAS Sulfate
Barium Chloride Total Dissolved Solids
Cadium Copper Zinc
Chromium (CR+6) Hardness (as CaCO 3 ) BOO 5
Cyanide Iron* COD*
Specific Conductance*
Fl ouri de Manganese
Lead Nitrate
Selenium Phenols*
Silver Sodium
*These parameters to be monitored quarterly; all the others annually.
Methane Gas
A methane gas management system can only be selected after gas
testing has been conducted upon the landfill and the surrounding area.
A commercial gas testing unit can be utilized to check for the presence
of gas. Specific locations to check would be the homes along Artillery
Road, the area across Old Baird Road, the dog pound, garage and in the
cover soil.
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Gas monitoring wells (Figure 4) may be installed in various
locations surrounding the landfill to allow for easier continual
monitoring. The soil surrounding the landfill should be tested for its
porosity, grain size distribution, etc. to enable one to gain further
Insight Into what might be the most likely avenue for lateral gas flow.
A methane gas relief vent (Figure 7) could be installed throughout the
landfill to aid the vertical escape of the gas and lessen its effect
upon the grass cover.
Any change in the present soil used as cover may induce a change in
the gas’s ability to be vented vertically. Specifically, the selection
of a more impermeable cover to minimize water percolation may induce a
pressure build—up within the landfill and cause the gas to migrate
laterally. In this case, a formal venting system may be required. In
the event that a gas venting system Is deemed necessary at this site, we
recommend that an active venting system rather than a passive system be
selected. It has been our experience that an active system Is greatly
superior to a passive one In controlling gas migration.
Lastly, we would like to repeat our suggestion that the town
consider utilizing the landfill’s gas as a fuel supplement for the dog
pound and/or the town garage particularly if gas control Is found to be
necessary.
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SITE EXPANSION AND FINAL USE
Any expansion of this landfilling operation can only proceed by
balancing the costs and liabilities incurred by the town versus the
benefits received by having a convenient disposal facility.
The present landfill is properly operated and its primary
environmental Impacts of ground and surface water pollution have been
minimized. Any expansion of this landfilllng operation must be examined
from the prospective of what liability the town may gain.
Currently the United States Environmental Protection Agency (USEPA)
is promulgating new solid waste regulations known as the Resource
Conservation and Reco ery Act (RCRA). It Is an all encompassing act
governing the disposal of solid and liquid wastes. Although RECRA has
not been officially promulgated, we believe It Is just a matter of time
before It does become law. There is one section of this act which has
profound impact upon this landfill and more so upon any proposed
landfill expansion. Section 4002 of RCRA involves the
identifIcation/closing/upgradIng of open dumps. It is our interpretation
of this particular section’s criteria that any future expansion of the
Watertown landfill would probably be classified as an open dump unless
such expansion Included the utilization of bottom liners, leachate
collection and treabnent etc. The Town may want to evaluate any
landfill expansion plans In relation to the costs that may be required
in order to fulfill the Intent of RCRA.
The landfilling operation has already begun to fill the southern
portion of the site with no apparent impact upon the marsh. We
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recommend that the landfill operation be limited only to that general
area. Specifically, we recommend:
(1) The vertical expansion be limited to elevation 760, so as to
blend In with the existing completed tier; and
(2) The horizontal expansion be limited to that area north of the
grassy dirt mound which exists next to the sediment basin. It
is extremely important that the horizontal landfill expansion
allows for the construction of the drainage ditch extension
previously recommended. Any filling beyond this mound would
prevent the proper diversion of leachate and surface run—off
into the basin.
We recommend that this landfill be utilized as a recreational area
for at least a few years after Its closure. This time period will allow
for the solid waste to undergo a considerable amount of settlement and
gas generation. Any construction contemplated on this site should
include a methane gas warning/venting system and a rigorous foundation
investigation.
Our remedial recommendations are shown on Figure 2.
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Costs
We have prepared an estimate of the Implementation cost of our
recommendations for this facility. These costs have been tabulated and
are shown In Table S. The basis for these costs was the 1980 Dodge
Construction Manual and the past experience of Wehran Engineering with
similar landfill construction. The actual cost of some of these items
could be much less if the Town Public Works personnel and equipment are
utilized in construction.
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TABLE 5
TABLE OF ESTIMATED COSTS
Watertown Sanitary Landfill
l.Jnl t
Item Description Unit Price Quantity Amount
Combustible Gas Mine Safety Model Ea. $381.90 1 $381.90
Indicator 53 (or equivalent)
Gas Monitoring Drilling and Mater— Ea. 280.00 6 1680.00
Well ials
Grass Cover Hydraulic Spreading
Lime, Fertilizer
and Seed Ac. 1200.00 12 14400.00
Refurbishing and Excavation and Soil
Extending Drain— Removal
age Swales LS 4000.00
Level Spreader Excavation and Soil
Removal /Pl acement
Rip—Rap Placement LS 3000.00
Soil Testing Grain Size Dist. Ea. 32.00 6 200.00
Ea. = Each
Ac. = Acre
LF = Linear Feet
LS = Lump Sum
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BIBLIOGRAPHY
A.W. Martin Associates, Inc., Evaluation of a Leachate Collection and
Treatment Facility in Pennsylvania , USEPA, Project No. WH—404, December,
1977
Business Week , “Buirushes That Eat Pollutants”, March 10, 1975.
New England Construction , “Water Polluting Leachate from Landfills
Caught and Treated in New System”, June 26, 1978.
Mosher, Dale C., “The Federal Ground—Water Protection Program -
Tommorrow’s Undoing”, Ground Water , Volume 1, January—February 1979.
_________ Internal Memorandum to Mr. Truett V. DeGeare Jr., USEPA,
1976.
Pavoni, Joseph L. et al, Handbook of Solid Waste Disposal , Van Nostrand
Reinhold, 1975.
Small, M. M., Wetlands Wastewater Treatment systems , U. S. Department of
Energy, Contract No. BY-76-C-OZ—OOl6, May 1918.
_____________Marsh/Pond Sewage Treatment Plants, U. S. Department of
Energy, Contract No. E(30l-)-16
U.S.E.P.A., An Environmental Assessment of Potential Gas and Leachate
Problems at Land Disposal Sites , Report No. SW—lb of
U.S.E.P.A., Gas and Leachate from Landfills , EPA—60019-76—004, March
1976.
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APPENDIX
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POTABLE
WELL
GROUNDWATER
MONITORING WELL
LEACHATE
CMP DRAINAGE
PIPE
SEDIMENTATION
PONO
REFERS TO PWOT( 3RAPW AND
DIRECTION OF VIEWING
____ LANDFILL
WEIR No.3 i’ 1p. _ \\
SANITARY
WATERTOWN
LANDFILL
NOTE: 1 )415 MAP IS BASED UPON INFORMATiON CONTAiNED
N THE R. lIAESTAD, PART B REPORT
EHRAN ENG1NEER!NG SITE LOCATION MAP
NOT TO SCALE
CQNSUI11NG ENGNEERS
FIGURE
OCTOBER 4,1979
WATERTOW N
-------
1. Looking South towards an active face.
N’otice In foreground gravelly soil cover
and a sparse grass population. This
l andflll area was not being used on the
date of our inspection; however, cover
material was being stockpiled for future
use, see piles in left background.
Sedimentation pond Is in middle of the
photo gra ph.
3. Looking Southeast into the sedimentation
pond. An orange/copper color was predominant
throughout the pond. No animal life was
observed on this date. However, we were
.told by the State Inspector that he had
observed frogs and a family of ducks living
there.
.4
I
2. Looking South towards the active face
which is being utilized on the date of
this inspection. Note lower area in the
middle of the photograph. The landfill
operation is anticipated to fill this area
in the future.
-------
. .yi W
- — p.••’ • - . . . - - - —S
S - -- - -.
- , i--
I c -
_?1
, .- - -,
lip
- - ..r -. - - —‘
- -- .
- S
.
: ft
‘ .- e
4. Looking North into the active face.
Notice in foreground a swamp area. This
swamp appeared to be localized and not
connected to the swamp(s) located across
Artillery Road. Note the (two) tiers of
land. The area in the background
is the completed landfill area on which
photographs 1 and 2 were taken from.
5. Looking South into the first swamp area.
This photograph is taken of the effluent
right after it travels beneath Artillery
Road. Frogs were observed sunning them-
selves upon the sand bar. A few dead trees
were observed in this swamp but much of the
vegetation was lush.
-4’,’ 4 - —
C
— ‘F-- -
• - - • -
• - -.
.5.,
-•- ‘,-.- • —b-• 5 --
-: 14?& - 1: _-, .-
_:‘
--- #•‘,—. •- -• - -4-
- 5-. - S -
• ‘ - k-- - .--.
- _ ‘__$1 . ç :’. T-
p
-------
6. Looking South into the second swamp
area. No apparent impact of the
effluent was observed in this area.
Much of the vegetation was lush.
7. Looking into Lake Winnemaug along a
stream which is fed by the swamps.
The stream appeared to be healthy
and contain clear running water.
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DRAINAGE SWALE
TO SEDIMENT
TO EXTEND
POND
A
SEDIMENT
POND
LEVEL
No.2
METHANE
MONITORING
OLD LANDFILL
WEIR No. 3
LAKE
WINNEMAJJG
RECOMMENDED LANDFiLL EXPANSION
L
FiGURE 2
WEHRAN ENGINEERING
REMWIAL ACTION
PLAN
NOT TO SCALE
TOWN OF WATERTOWN
SANITARY LANDFiLL
N
0
GRASS COVER
BE APPUED
a
MOUND
S P ADER
A
WELL
GAS
CONSULTiNG ENGINEERS
WATERTOWN CONN
-------
SEDIMENT BASIN
N J MARSHjL )
—BERM TO TIE INTO
EXISTING SLOPE
Al]
PLAN VIEW
OVERFLOW
BERM
LEVEL
NOT TO SCALE
I. THE ABOVE CONSTRUCTION COULD BE REPEATED F THE
OUTLET PIPE UNDER ARTiLLERy ROAD IF DEEMED NECESSARY.
2. THE OUMPED STONE RIP- RAP SHALL CONSIST OF COBBLE AND
BOULDER SIZED FRAGMENTS OR SELECTED CONSTRUCTION DEBRIS.
3. THE EARTHERN BERM SHALL BE CONSTRUCTED IN 6 ’ LIFTS AND
AND BE SUITABILY COMPACTED.
FIGURE
0 0
GRAVEL
0 0
0
0
• FILTER
0
0
I
100’
T
—I
EMBANKMENT
100’
2’
SLOPE
FILTER
(Y)
NOTE ’
SECTION
SPREADERS
A-A
3
WE PRCLI1rT JA fl’)I QAcc
-------
2” SQUARE
EXISTING GROUND
2 ’ LOC K ING TYPE CLAP & BAILEY
NO. 291 FWSH BOX OR EQUIVALENT
CONCRETE SLAB
GROUT FILL
:; a
PROViDE SLOTS iN
• PIPE, R 12” LE NGTH
AT 5’ INTERVALS
2” SCHEDULE 40
PVC PIPE
GRAVE FiLL
VARIES
TABLE
F 1 . 6” ,
GAS MONITORING
WELL
FIGURE 4,
-------
S.
COVER
DETAIL OF DRAINAGE SWALE
I-
FIGURE
5
lv I a1flA
-------
a’
DETAIL OF DRAINAGE SWALE
WITH ERO ON CONTROL
GRASS COVER
NOT TO SCALE
r
DUMPED STONE RIP- RAP CONSISTING
OF COBBLE AND OULDEN SIZED FRAGMENTS
OR SELECT CONSTRUCTION DEBRIS.
FIGURE 6
-------
TEE
METHANE
GAS
PRESSURE REUEF VENT
NOT TO SCALE
STEEL RISER PIPE
MIN. IO’ABOVE GRADE
CEMENT G
GRAVEL
SO
LID
WA
SLOTTED 4” PVC WELLSCRED4
TO BOTTOM oc SOLID WASTE
ST C
S 0 L
ID
WASTE
FIGURE
02149055
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