OF DANBURY, CT 2002 PLAN OF
DEVELOPMENT TEXT CONCERNING SEWERS
The following text is drawn
from the Danbury Plan of Conservation and Development Town
Plan which became effective in 2002. all of the text that
follows in this section is copied directly from the Danbury
The City of Danbury has extensive municipal sewer and water
supply service areas covering the most densely populated areas
of the City. At present, most scheduled capital improvements
for the two systems are limited to rehabilitation and replacement
projects rather than major service expansions.
adopted sewer and water plans propose substantial expansions
in the future. Additionally, with more stringent federal regulations
in place under the Safe Drinking Water Act, community water
systems are seeking to be taken over by larger systems such
as the Danbury Water Department.
West Side is where the most utility demand is anticipated
as substantial new growth is projected in housing, light industry
and commercial development. While municipal sewer lines serve
a portion of the area, some are inadequate for projected growth.
Thus, one of the City's largest capital projects will at some
future time be the construction of a sewer interceptor and
its network transporting West Side sewage flows to the downtown
sanitary sewer system and ultimately to the municipal treatment
plant off Plumtrees Road.
second major utility issue concerns the effect of sewer systems
on the public water supply watershed's in Danbury. Sewers
are not, by themselves, harmful to these watersheds, and in
fact can be beneficial if they correct failing septic fields
and mitigate the threat of contamination or industrial discharges.
However, the extension of sewer service may also encourage
growth into areas that heretofore were largely undeveloped.
The additional development may result in increased runoff,
pollution, and the diversion of groundwater away from the
the City's policy is to allow only on-site sewage disposal
systems within the watershed areas, and to allow extension
of sewer services to these areas only if the on-site systems
are failing and repairs are infeasible. The exception to this
policy is the Lake Kenosia area on the West Side, as sewer
service was installed there prior to the Lake's designation
as a public water supply source.
Kenosia and its watershed are now elements in the City's potable
water supply. Thus, the West Side will become an important
test of the City's ability to promote economic development
while protecting public water supply watersheds.
The City of Danbury provides sanitary sewer service to its
most densely populated area and to several adjacent towns
in the region. The sewage treatment plant has a permitted
treatment capacity of 15.5 million gallons per day (mgd),
and is operated under a permit granted by the Connecticut
Department of Environmental Protection (DEP).
City has entered into a twenty year contract with U.S. Filter
Operating Services to operate the plant but retains ownership
of the plant, pumping stations, and collection system. The
1990-93 expansion project added capacity, improved treatment,
and greatly reduced the pollutants discharged into the Still
River, especially ammonia. The plant's operations permit lapsed
several years ago but DEP has allowed the plant to continue
to operate while the new permit is pending.
sewage treatment plant dechlorinates and nitrides the effluent
prior to discharge. Depending on changing state standards,
the updated permit may require additional effluent treatment.
This may include a reduction in levels of metals (such as
lead, copper, silver, and zinc) and in levels of nitrogen,
changes that may require a substantial capital investment.
Additionally, converting some of the chemicals used from gaseous
to liquid form may be required to meet worker safety standards.
Danbury plant's 15.5 million gallon per day (mgd) capacity
is allocated primarily to the City (11.8 mgd), with varying
amounts to Bethel, Brookfield, Newtown, and Ridgefield. The
four towns have not yet reached their full allocation. In
addition, one million gallons per day are dedicated to regional
needs that can be allocated to more than one municipality.
from Danbury's 2002 Plan
showing existing and proposed sewered areas
demand on the sanitary sewer system has been the subject of
several studies: the Comprehensive Sewerage Study (Manganaro,
Martin, and Lincoln, 1967), the Sewer System Evaluation Survey,
Danbury and Bethel Area (Cahn, Inc., 1983) and the Comprehensive
Sewerage Study (Roald Haestad, Inc., 1987). According to Sewer
Service in the Region (HVCEO, 1992), the Danbury sewage treatment
plant has sufficient capacity to serve a total population
of 90,000 residents.
last study predicted that it was unlikely that the plant would
ever reach full capacity by Danbury residents alone. The study
also found that existing interceptors and trunk lines are
generally adequate for the projected population to 2020, with
the notable exception of the West Side.
priorities for the City are (1) areas with immediate problems,
such as failing septic systems or existing sewers with reported
overflows, and (2) areas expected to develop to a density
requiring sewers. Specifically, improvement to the existing
West Side system will be determined by the construction of
the West Side Sewer Interceptor.
major capital project was the subject of a 1989 study by Roald
Haestad, Inc., West Side Sewer Interceptor Design Report.
The study found the West Side interceptor to be required to
resolve both existing capacity and flow deficiencies and to
accommodate the projected increase in service demand as this
part of the City is developed. All other current capital projects
relating to sewer lines have less of an impact on growth than
the West Side project and are primarily restricted to replacing
sewage transmission lines, pumps, and equipment.
for Extending Sewer Service
Expansion of the sewer service area is based on projected
levels of development and density. The following principles
should be followed in assessing whether a new area should
be served with sewers.
The extension of sewer service should be seen as a method
of reinforcing proposed growth patterns of the Plan of Conservation
and Development, except where necessary to mitigate existing
or potential pollution problems from failing on-site systems.
The 1987 Comprehensive Sewerage Study warns: "If any
radical change is proposed, a review of the sewer capacity
should be made. Permitting high-density development for one
property in a zone of lower density may take up all of the
available sewer capacity and prevent development of other
properties in conformance with the existing zoning. These
effects are cumulative and may lead to the overloading of
interceptors and trunk lines further downstream."
Requests for sewer service extensions within the existing
service area limits should usually be approved as long as
the proposed development is in accordance with existing zoning,
the Plan of Conservation and Development, and other City regulations.
The following concerns should be taken into consideration
before granting an extension: the quality and quantity of
the proposed discharge, distance from the nearest sewer, available
capacity in the existing sewers between the discharge and
treatment plant, additional properties that could be served
by the extension, and characteristics of the proposed discharge.
Sewer service should not generally be extended into watersheds
tributary to public water supply reservoirs, nor should development
be permitted within the watersheds at densities that would
require or encourage sewer service. The objective in these
areas should be sewer avoidance, though there may be circumstances
where extending service within the watershed will alleviate
existing problems. The impact to the water supply must be
evaluated and means proposed to minimize adverse impacts.
Requests for extensions into areas other than public water
supply watersheds should be evaluated to determine the system's
capacity and its ability to serve the area. The applicant
will be required to fund the extension and any improvements
necessary to the system to maintain the established buffer
capacity, for property owners within the service limits should
not be penalized by allowing outside users to absorb available
Areas zoned for densities of one dwelling unit or more per
acre that lie outside the proposed service area boundaries
and inside the water supply watershed will need to be treated
on an individual basis if they create a demand for water and
sewer service beyond the recommended limits. In most cases,
however, the zoning of undeveloped land at such densities
should not be permitted outside the service area.
While Lake Kenosia is not considered a primary source of water
supply, its watershed is within the existing water and sewer
service area limits. Additional development within the watershed
should receive both water and sewer services, but such development
is restricted by zoning regulations affecting Class If public
water supply watersheds to prohibit or control potential sources
of pollution. Expanded sewer service on the West Side within
the Lake Kenosia watershed should follow a plan that focuses
on both orderly service extensions and watershed protection.
Major Improvement Needs
Major improvement needs for sewer service include the following.
Construction of the West Side Sewer Interceptor from the Union
Carbide Corporate Center to Segar Street for the purpose of
providing sewer service and additional capacity to the West
Replacement of the undersized Westville Avenue sewer to improve
capacity and prevent infiltration.
Replacement and upgrading of aging equipment at the Mill Plain
Road pump station.
Upgrading the sewer treatment plant to remove nitrogen and
The text above was taken directly from the 2002 Danbury Plan
of Conservation and Development, authored by Danbury Planning
Director Dennis Elpern.
A letter dated 7/1/2004 by Danbury Director of Public Works
William Buckley states "With respect to sewage capacity
at the treatment plant, please be advised that when the treatment
plant was upgraded in the late 1980's, the City of Danbury
was requested by the State Department of Environmental Protection
to design and construct an additional one million gallons
a day of capacity for regional needs. To date, the Town of
Newtown has purchased 150,000 gallons of that extra one million
and we are currently in discussions with Brookfield, Connecticut
for the purchase of somewhere around 75,000 gallons per day."
The City of Danbury's sewer plant
is the largest such
facility in the Region and also serves six nearby
towns. The title of this 1993 plant brochure stresses
the plant's role in regional environmental protection.
CT SEWER SERVICE HISTORY (UPDATED ONLY TO 1992)
Danbury, like many other cities, first adopted the expedient
of emptying its untreated sewage into the largest available
river, the Still River. In time farmers, mill owners, and
others downstream complained. In 1893 the State ordered Danbury
to build a filtration plant for treating its sewage, an early
precedent in Connecticut's water quality planning.
of Danbury’s sewers in modern times can be said to have
begun in 1960 when the City’s Plan of Development recommended
an expansion of the City’s sewer service areas. The
1967 updated Plan of Development rated the Beaverbrook area
on the eastern side of Danbury as the priority area for sewer
service expansion, followed by a second priority for the Danbury
Airport area to the west. The plan notes that the State Water
Resources Commission would not allow the construction of a
separate treatment plant in the Airport area because of low
stream flows in the Still River.
Accordingly, the plan to serve the Airport area required the
construction of an interceptor sewer line across the City,
following the course of the Still River. This sewer line was
also designed to serve urban renewal development efforts Downtown.
Future expansion of the sewer system was proposed for the
northern and western areas of the City.
1967, a comprehensive sewerage study for Danbury was prepared
by Manganaro, Martin & Lincoln. The report projected that
the City’s population would increase to 77,000 persons
by the year 2010, with 65,000 residents receiving municipal
suggested stringent zoning restrictions in the northwest area
of the City in order to eliminate the need for municipal sewer
service extensions there, and to protect the watersheds serving
the City’s municipal reservoir system.
The report also suggested connections to Brookfield’s
Federal Road area and Bethel’s Stony Hill area.
CT TREATMENT PLANT
CAPACITY (UPDATED ONLY TO 1992)
The comprehensive sewerage study in 1967 projected average daily
flows of sewage needing treatment in 1985 at 12.5 MGD and in
2010 at 19.1 MGD. In 1969, a City referendum authorized a $9
million program of improvements to the sewerage system including
increasing the sewage treatment plant’s capacity from
5.0 MGD to 12.0 MGD.
the sewage treatment plant had been expanded and the Beaverbrook
and Airport interceptor sewer lines constructed. The first
regional connection to the Danbury municipal system would
soon be in place via an intermunicipal agreement with Brookfield
for 0.5 MGD of treatment capacity.
sewer lines connecting to the Danbury treatment plant are
generally defined as those sewers with a diameter greater
than 12 inches which are used to transport collected sewage
to the treatment facility.
temporary phosphorous removal facilities were installed at
the Danbury treatment plant in response to a CT DEP pollution
due to CT DEP imposed changes in water quality standards for
concentrations of phosphorous and ammonia, pollution abatement
orders were issued to both Bethel and Danbury to upgrade the
quality of the treated effluent discharged from their respective
sewage treatment plants. CT DEP’s motive for this action
was to raise the classification of the streams receiving treated
sewage effluent from a unacceptable C classification to an
acceptable B classification.
Wastewater Management Plan by Calm, Inc. proposed that Bethel
and Danbury sewage systems be combined, with all Bethel sewage
treated at the upgraded and expanded Danbury plant. This would
result in a significant reduction in the level of nutrients
entering the Still and Housatonic Rivers, also aided with
the incorporation of a phosphorus removal process at the upgraded
Danbury sewage treatment plant.
But one of several effluent discharge ideas raised by the
City was the piping of treated sewage effluent directly to
the Housatonic River so that the effluent would be diluted
by the greater volume of water and thereby reduce the need
to upgrade the level of treatment in the Danbury treatment
plant. This idea was rejected by CT DEP.
1988 CT DEP increased the approved capacity of the proposed
plant renovation to 14.5 MGD. In late 1988 CT DEP directed
that plant capacity be increased by an additional 1.0 MGD
to 15.5 MGD in order to accommodate potential regional needs.
A 1989 report prepared for the City of Danbury by Metcalf
& Eddy entitled Update to the Wastewater Management Facilities
Plan -Danbury and Bethel Area. Connecticut, recommended allocating
0.7 MGD of the CT DEP’s required 1.0 MGD a potential
regional needs capacity to Brookfield, and 0.3 MGD to New
rejected this recommendation due to concerns that New Fairfield’s
requirements for treatment could exceed the proposed 0.3 MGD
allocation. Ridgefield’s current allotment of 0.14 MGD
was to remain unchanged. Additional flow capacity will eventually
be required in some Danbury interceptor sewer lines in order
to accommodate the increased volume of sewage projected from
of the expanded and upgraded Danbury sewage treatment plant
began in 1990 with completion scheduled for 1993, as mandated
by a CT DEP order. The plant will have a CT DEP permitted
treatment capacity of 15.5 MGD. As of February of 1991, CT
DEP had allocated the capacity of Danbury’s treatment
plant as follows:
11.8 MGD. The City's current flow is about 8.25 MGD.
2.0 MGD. Bethel currently flows (1992( .05 MGD. The estimated
flow to Danbury in 1993, after abandoning its present treatment
plant, is projected at 1.3 MGD.
0.8 MGD, of which 0.5 MGD is from a current agreement with
Danbury and 0.3 MGD is allocated by CT DEP to Brookfield for
"regional need." Brookfield currently flows 0.15
MGD to Danbury.
0.7 MGD, all of which is allocated by CT DEP as part of "regional
need." There is no current flow from New Fairfield to
Danbury. Sewage flows from New Fairfield to Danbury’s
system would require increasing the capacity of the affected
Danbury interceptor sewer lines.
0.0 MGD at present (1992), to be negotiated. Newtown has requested
0.4 MGD of Danbury capacity to serve economic development
in the Hawleyville Ar ea. Ridgefield:
0.14 MGD. Ridgefield currently flows 0.09 MGD to Danbury,
under an agreement for a 0.14 MGD flow cap.
CT DEP’s required 1.0 MGD "regional needs"
category is distributed as follows: Brookfield 0.3 MGD; New
Fairfield 0.7 MGD.
has enough surplus capacity reserved in its new sewage treatment
plant to allow for a total population served of approximately
90,000 city residents, which is the saturation population
possible under Danbury’s present zoning map for both
sewered and non-sewered areas. The saturation population estimates
also include assumptions that permit the continued economic
growth of the City.
enlargement of the Danbury plant is restricted and possibly
prohibited by the capacity of the Still River to receive the
treated sewage effluent and still retain a B quality designation,
as mandated by CT DEP. Any requirement for extreme purification
of the sewage effluent may be more expensive than piping it
directly to the Housatonic River, an old but recurring idea,
where greater river flow would more effectively dilute the
discharge of treated sewage effluent.
Mandated Future Regional Needs Set-aside
CT DEP has mandated that an additional 1.0 MGD of treatment
capacity be built into the upgraded Danbury treatment plant
for future regional needs. This additional treatment capacity
is currently allocated to New Fairfield- 0.7 MGD, and to Brookfield-
0.3 MGD. Neither municipality has agreed to pay for the CT
DEP mandated allocations.
of Danbury, which is responsible for the maintenance and operation
of the Danbury sewage treatment plant, questions the allocation
of 1.0 MGD for future regional needs on the grounds that the
City should not be required to pay for the construction and
maintenance costs of plant capacity which has been mandated
by the State to serve other municipalities.
would like to have a portion of the additional treatment capacity
for future regional needs allocated to Newtown for its proposed
sewer line serving the Hawleyville area. This would maintain
the integrity of Danbury’s share of the treatment plant’s
capacity and would provide fiscal relief to the City, with
Newtown paying a prorated share of the construction and maintenance
costs of the CT DEP mandated additional regional capacity.
CT DEP has indicated that it will not reallocate the additional
regional capacity until it has been proven that neither Brookfield
nor New Fairfield require this treatment capacity. The time
frame to complete the studies required to determine the needs
for sewerage treatment capacity in these communities would
be mid 1993 at the very earliest.