HomeMy WebLinkAboutNorth Fork Water Supply Plan-Executive Summary & Recommendations by SCDHS Dec-82ERH-North==st
D'RAET
NORTH FORK WATER SUPPLY PLAN
EXECUTIVE S~ARY
AND
RECOM>[ENDATIONS
December 16, 1982
Prepared For:
Suffolk County Department of Health
Hauppauge, New York
Services
ERM-Northeast Engineers,
88 Sunnyside Blvd.
Plainview, N.Y.
by:
P.C.
Camp, Dresser & McKee
One World Trade Center
New York, N.Y..
ERH-Horth , [t
SECTION 1.0
EXECUTIVE SUb[MARY AND RECOI~M'ENDATIONS
1.1. Executive Summary
Water supply problems on the North Fork of Long Island are
severe. Shallow, thin groundwater aquifers are extensively
impacted by contamination from agricultural chemicals, primarily
nitrates and pesticides, and are threatened by saltwater intru-
sion from over-pumpage. Increasing pressures for development
which will result in accelerated population growth will further
stress the water supply aquifers.
In response to the threats to groundwater quality and the
increased demands for potable drinking water, the Suffolk County
Department of Health Services sponsored a study of water supply
options for the North Fork. The objectives of this North Fork
Water Supply Plan were to develop and evaluate several alterna-
tive water supply plans which could safely meet present and
future potable water requirements and recommend a future course
of action.
The planning area includes the Towns of Riverhead and
Southold. Since hydrogeologic conditions are significantly
different throughout the area, five Water Supply Zones were
established for planning purposes. Zone 1 starts at the
western town boundary of Riverhead and extends easterly to
the hamlet of Riverhead. In this zone, the Magothy aquifer
is saturated with fresh water all the way to bedrock. The
presence of saltwater increases in the lower portions of'the
Magothy as one progresses east from the hamlet until the
fresh water lens terminates at Mattituck Inlet which is the
eastern boundary of Zone 2. Zones 3, 4, and 5 are defined by
three isolated fresh groundwater lenses. Zone 3 extends from
the }~attituck Inlet to Hashamomuck Pond. Zone 4 extends from
Hashamomuck Pond to Dam Pond; Zone 5 starts at Dam Pond and
continues through Orient Point.
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Area Characteristics
The Long Island Regional Planning Board estimates that
permanent population in the study area will increase from
approximately 39,000 today to 49,800 in the year 2000. On
a peak summer weekend, an additional 32,000 persons are
anticipated.
Agricultural land use is the most prevalent in the study
area today, accounting for approximately 42% of the land area
(29,560 acres); current residential land use accounts for 12%
of the area. Future land use projections by the Regional
Planning Board indicate that low density residential develop-
ment will significantly increase in both Tokens, while agri-
cultural usage will decrease. The land use trends projected
by the Planning Board forecast a decline in agricultural
land of approximately 18% (5,300 acres). Furthermore, the
Cooperative Extension Service anticipates a gradual change
in the types of crops grown on, the North Fork. In general,
potatoes, sod and rye acreage will decrease while grapes,
mixed vegetables, horse farms and nursery stock will increase
in acreage.
Groundwater Quantity
The major geologic units in the two Towns are bedrock,
the Raritan Formation, the Matawan Group (Magothy Formation
aquifer) and Pleistocene deposits (glacial deposits including
the upper glacial aquifer).
The principal water supply source in the study area is
the upper glacial aquifer. It is a highly productive water-
bearing unit with consi~tent physical properties.
In the eastern part of Water Supply Zone 2 and in Zones 3,
4, and 5, a very delicate balance exists between frgsh ground-
water lenses, saltwater intrusion, chemical contamination and
water supply requirements. The fresh groundwater lense~ are
relatively~thin; therefore, the total available supply is
limited. Over-pumpage or improper well location causes lateral
and vertical saltwater intrusion. The aquifers are extremely
susceptible to chemical contamination because they are shallow
and have limited dilution or assimilative capacity. Groundwater
flow velocities are very low (on the order of one foot per day)
so it takes long periods of time for contaminants to flush out
of the aquifer (up to one'hundred years). These conditions man-
date that groundwater resources be properly managed and protected
in order to be able to support necessary water supply require-
ments.
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Consumptive water use patterns will change in the study
area over the next twenty years. Domestic requirements
(including commercial and industrial) will increase by 25%
from an annual average of approximately 4 mgd today to over
5 mgd in the year 2000. Agricultural usage, however, will
decline by 18% from 11 mgd to 9 mgd. During summer months,
domestic consumption is expected to be over 6 mgd; agri-
cultural consumption will be approximately 22 mgd. The trend
to residential development from agriculture will result in a
slight overall decline in average daily water use over the
planning period but the demand for uncontaminated, potable
water will increase.
In order to estimate the total quantity of groundwater
that may be withdrawn from larger capacity public supply wells
from each Water Supply Zone, water budget areas were delineated.
Substantial amounts of groundwater are available outside of the
budget areas but, to avoid saltwater intrusion, can only be
withdrawn by small, domestic capacity wells.
In Zones 1 and 2, the budget areas were defined as those
locations~where the groundwater level is five feet or more
above sea level. In Zones 3, 4 and 5, the availability of
groundwater is more limited so the budget area boundary was
defined as the two-foot groundwater contour. A total of
approximately 41.2 mgd of fresh groundwater is available
from the budget areas. An additional 10 to 20 mgd is avail-
able for domestic wells outside of the budget areas. The
results of the water, budget analysis, by Zones, are shown
below in Table 1 which also includes consumptive use pro-
jections for the year 2000.
Table t
Permissive
Water Sustained Yield,
Supply Budget Area
Zone mgd
1 29.4
2 5.6
3 4.9
4 0.9
5 0.4
TOTALS: 41.2 mgd
Domestic
~Consumptive Use,
Year 2000,
msd
2.25
0.97
1.18
0.59
0.11.
5.10 mgd
Agricultural
Consumptive Use,
Year 2000,
mgd
3.06
3.06
2.80
· .o.o¥
0.35
9.31 mgd
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Conclusion: Sufficient fresh groundwater is available to
satisfy the needs of the overall planning area. However, criti-
cal water supply conditions exist in Zone 5 (Orient) where
projected requirements are approximately equal to available
supply. Groundwater supply conditions in Zone 4 (Greenport/
Southold) are also critical although there is some extra avail-
able supply (0.9 mgd available versus 0.63 mgd required).
Groundwater Quality
The upper glacial aquifer throughout the planning area is
already contaminated with nitrates and organic pesticides and
herbicides. Nitrate levels are significantly elevated above
natural background conditions (0.1 to 1.0 mg/1) and exceed the
drinking water standard of 10 mg/1 in many areas. A sampling
of 639 wells for nitrates by the SCDHS in the Town of Riverhead
showed: 58% of the samples ranged from 0 to 5 mg/1; 26% were
above 7.5 mg/1.; and, 16% were above 10 mg/1. Similar results
were obtained in a sampling of 1,121 wells in the Town of
Southold; 51% of samples ranged from 0 to 5 mg/1; 30% were
above 7.5 mg/1; and, 17% were above 10 mg/1.
Organic contamination from pesticides and herbicides is
also widespread.· A comprehensive survey to define the extent
of contamination from one pesticide aldicarb - was conducted·
by the SCDHS in 1979 and 1980. In the Town of Riverhead, 2,161
wells were samples; 32% were contaminated by aldicarb;-16% had
aldicarb concentrations above the health guideline of 7 ppb.
In the Town of Southold, 3,160 wells were sampled; 23% showed
aldicarb contamination; 11% exceeded the health guideline of
7 ppb.
Numerous other agricultural chemicals have also been found
including carbofuran, dacthal, dichloropropane, oxamyl and dinoseb.
Nitrate contamination is vertically extensive throughout
the upper glacial aquifer. Aldicarb and other organics are
presently limited to the upper 40 feet of groundwater. However,
they are expected to distribute throughout the'aquifer over~
time. Since velocities of flow are on the order of one foot per
day in the North Fork aquifers, contaminants will be present for
many decades before they are flushed out.
The amounts of uncontaminated groundwater available for
consumption, although not quantifiable, are substantially, less
· than those shown in Table 1. When groundwater flow ~s con-
sidered, almost all of Zones 3, 4 and 5 become suspect as well
as the upper 50 feet of groundwater in Zones 1 and 2.
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Conclusion: Water supply planning for the North Fork must
proceed on the following basis: groundwater contamination is
currently extensive and will remain so for many years. As
additional groundwater quality data is collected, more contam-
ination problems will be discovered. Alternative solutions
must consider the fact that a limited volume of fresh ground-
water is, in a sense, further limited because large portions
have been contaminated by agricultural chemicals.
Water Supply Alternatives
There are several levels of development on the North
Fork, all of which had to be considered in the .planning process.
Five areas of population concentrations were defined as major
water supply demand centers: (1) Wading River/Northville;
(2) Riverhead/Jamesport; (3) Mattituck/Cutchogue; (4) Southold/
Greenport; and, (5) Orient. Distinct individual communities
(e.g., Calverton, Little Hog Neck, East Marion) comprise the
demand centers. The remaining areas were considered low den-
sity residential and rural and were considered separately.
The development of alternative water supply plans to serve
this broad spectrum of needs proceeded in a building block
fashion beginning with an evaluation of individual home wells
through community systems to large, regional systems. Five
levels of water supply alternatives were developed and evaluated:
Level I:
Individual Home Systems in areas where ground-
water was degraded, these would include treat-
ment of the home supply.
Level II:
Level III:
Level IV:
Neighborho6d Systems these are small municipal
systems serving 2 to 50 homes.
Community Systems serving individual communi-
ties with local groundwater.
Sub-Regional Systems serving an entire demand
center with local ~roundwater..'
Level V:
Regional Systems - wherein the supply is uncon-
taminated groundwater from Riverhead piped via
a major transmission main to the eastern por-
tions of the study area.
In addition to the above listing, dual water supply systems,
bottled water, clean water vending machines, truck-delivered water
and a central, community water supply tap were also evaluated as
part of this study.
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ERH-Horth~st
Preliminary engineering studies and designs were developed
for each alternative. Capital cost estimates were prepared and
annual amortization and operation/maintenance/administration
costs were also estimated. The cost estimates ranged from $155
per year per home for individual bome wells in areas where
groundwater was potable to over $2,000 per year per home where
extensive treatment was necessary or where clean groundwater
had to be imported over long distances from other areas.
Because of low density development, the relative costs of
distribution systems are extremely high in the planning area
and preclude the development of municipal systems in many areas.
In addition to comparing the costs of alternatives, several
other factors were considered in the screening and evaluation
process:
1.) Reliability of operation
2.) Environmental consequences
3.) Implementation problems
4.) Flexibility to respond to future problems
Conclusion: Some form of direct governmental involvement
is needed to insure continued receipt of potable water by resi-
dents in the area. In general, the study found that a combina-
tion of community water systems and individual home treatment
units was the preferred course of action.
Implementation
Under the provisions of New York State
institutional entities that could implement
the selected alternatives:' villages, towns,
Suffolk County Water Authority.
law, there are four
all or portions of
coun{ies and th~
Implementation at the Town level will give local govern-
ment the~ability to provide public water systems'in response
to the needs and desires of the people. Expenditures and cash
flow would remain in the control of the Towns and they would
retain a great deal of flexibility in the types of publi~
water supply facilities to be provided for individual areas.
Legislation at the County or State level is not required
if the Towns implement the study's recommendations. 'If the
Towns do not choose to implement, the County would have to
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consider creating-water districts for implementation; the County
could operate the districts or contract to the Suffolk County
Water Authority. County implementation would require legisla-
tive action at the County level.
This investigation also included an analysis of funding
sources to assist in implementing the recommendations. No
such sources were found which are currently funded. Thus, the
improvements will have to be paid for at the local level, pri-
marily through user charges.
Conclusion: The Towns of Riverhead and Southold can best
implement the study's recommendations: (1) by forming Water
Supply Districts, covering the entire Towns' area, by petition
of the residents or subject to a permissive referendum; or,
(2) by providing for water improvements as a town function in
the entire area of the Town without establishing a District.
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1.2 Recommendations
General Recommendations
o
o
This investigation has demonstrated conclusively that numerous
technical and financial difficulties are encountered when
attempting to provide potable water to the residents of the
North Fork. '~Preventative measures to minimize or eliminate
additional groundwater contamination must be implemented
together with a public water supply systemY Preventative
measures are not immediate solutions to current water supply
problems but are desireable and necessary long-term actions.
Because of severe groundwater quality problems in the study
area, a safe, dependable water supply must be provided to
the residents of the North Fork. ~A combination of individual
home treatment units plus public water systems should be
implemented.~ f .~
The Towns of Riverhead and Southold should individually assume
responsibility for implementing water supply programs within
their boundaries. Administratively, the Towns should establish
Water Supply Districts or Water Improvements, encompassing the
entire areas of the Towns, for implementation of the plans and
recommendations of this study. As an incorporated village,
Greenport cannot be included in the Southold District unless
it petitions the Town for inclusion.
Technical and administrative water supply exptertise exists
with the personnel operating the water systems in the hamlet
of Riverhead and Village of Greenport which can be utilized
by the Towns. Since the Riverhead system is currently a
part of Town government, institutional arrangements would
not be required to utilize the expertise. In Southold, the
Town Gan: establish its own water supply staff; contract
with Creenport for water supply services beyond those which
are currently provided by the Village; or, employ a combin-
ation of Town staff and Village services.
The Town Water Supply Districts should include individual
home treatment as part of their overall responsibilities.
In order to ensure safety and reliability, the Town Water
Supply Districts should own, operate and maintain the home
treatment units, not the homeowner.
In areas of existing development where groundwater, is ion-
taminated, the Water~ Districts#should provide public water
systems if economically feasible" If public systems cannot
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o
be implemented, home treatment units should be publicized and
recommended by the District and, if existing homeowners request
service, the District should provide, own and maintain the home
units.
l~en new subdivisions are proposed in areas of groundwater con-
tamination or potential contamination, connection to existing
public water supplies of adequate capacity are required. If
such supplies are not available, then new public supplies are
to be constructed by the developer and deeded to the Town Water
District.
If an existing home is sold in an area of suspected groundwater
contamination, the SCDHS or other appropriate agency should
sample and test the home well and the results should be attached
to the deed. If the water quality does not meet standards, the
current homeowner should make provision through the Water Dis-
trict to Provide a safe water supply prior to the sale of the
home. ~
The SCDHS is planning to locate a vending machine in the study
area which will purify local groundwater and sel'l the purified
water at a nominal cost. If the concept is accepted by the
citizens of the area, other vending machines should be located
by the Water Districts throughout the area as interim measures
until the other recommendations of this study are implemented.
Area-Specific Recommendations
10.
Wading River/Northville The existing individual water systems
in Wading River, Baiting Hollow/Woodcliff Park and Reeves'Park
should be connected to new supply wells which will separately
serve each of the three individual sub-systems. This is
necessary to improve the reliability of the supply and to
assure potable water. The new facilities should be located
and sized to also serve areas which do not currently have
public water systems; the new service areas should be'developed
in a phased approach. ~
The Riverhead Town Water District should own and operate the
new supply wells and transmission lines and should-sell water
to the individual water systems through metering facilities.
If any of the private systems want to deed their facilities
to the Town, the Water District should accept them.
It is not economically feasible to provide public Water systems
to the remainder of the area; these residents should~continue
to be served by individual home wells, with treatment as re-
quired, as part of the Town Water District.
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11.
12.
13.
Riverhead/Jamesport - The Riverhead system should he'extended
to serve the Calverton area and should actively attempt to
further expand its system to other areas adjacent to the pre-
sent system. Major improvements are not required in the
Riverbead system except for additional distribution system
storage. The remainder of the area, including Jamesport,
should continue to be served by individual home wells with
treatment as required, since it is not economically feasible
to serve those areas with public water facilities.
Mattituck/Cutchogue The Southold Town Water District should
acquire and operate the existing water system in Mattituck
Hills (Captain Kidd); measures should be taken immediately to
upgrade the performance and reliability of the system and to
augment its source of supply. In the remainder of the Matti-
tuck/Cutchogue demand center (including Cutchogue, Mattituck,
Little Itog Neck, East Cutchogue, Fleets Neck, New Suffolk and
Indian Neck), it is not economically feasible to provide
public water supply systems. ~These areas should continue to
utilize individual home wells; when treatment is required, it
should be provided through the Town Water District.
Southold/Greenport - The Greenport Municipal System, which
presently serves Greenport and parts of Southold, should con-
tinue to rely on local groundwater sources. However, major
improvements to the system are required. The existing Dono-
hue Farm well should be upgraded (450 gpm total capacity)
and used for public water supply. A 2.2 mgd reverse osmosis
treatment plant should be constructed in stages to treat the
water from the Donohue Well and existing Plants Nos. 6 and 7
for removal of nitrates, pesticides and herbicides.
After implementing the improvements, the Greenport system
should actively attempt to further expand its system to other
areas adjacent to the existing system. Such expansion should
not be permitted, however, until the recommended modifications
have been completed.
The activities of the Town Water District should not impact
the existing c~stomers of the Greenport system that are
located in the Town; their charges should only reflect the
costs of operating the present Greenport system after it is
upgraded.
In the remainder of the Greenport/Southold area, including
Great Hog Neck and East MariQn it is not economically feas-
ible to proPide public water supply systems. These .area~
should continue to be served by individual home wells, with
treatment as required, provided through the Town Water District.
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14.
15.
16.
Orient - The Orient area, with its relatively low density
of development, cannot economically support public wat.er.
Existing development should continue to be served by indivi-
dual home wells with treatment as required. Since the avail-
able fresh water supply is extremely limited, it is further
recommended that development in the Orient area be tightly
controlled to conform with existing zoning and result in
water requirements which are consistent with the permissive
sustained yield of the aquifer in Zone 5. It is further
recommended that only variances resulting in less water
usage, be approved. If future development is allowed to
occur which is more water-use intensive than the current
land use, desalinization may be required since the per-
missive sustained yield of the aquifer in the area will be
&xceeded and the importation of water from the west is too
costly.
Neighborhood Systems - Public water systems for existing
isolated neighborhoods in areas of groundwater contamination
are generally not economically feasible. Therefore, it is
recommended to continue to serve these areas by individual
home.wells, with required treatment provided through the
Town Water Districts.
Regional Pipeline System - The development of a major supply
of uncontaminated groundwater in eastern Riverhead and piping
it via a major transmission main to the eastern portions of
the study area wag a major alternative considered in the
study. It is not recommended for the following reasons:
the pipeline would encourage levels of development
which appear to be inconsistent with the current
life style of the people and the general character
of the area.
the construction of such ~ pipeline would require the
-up-front commitment of major financial resources and
resolution of numerous institutional issues. Both-
problems would require a great deal of time to resolve
and the water supply problems of the North Fork cannot
tolerate the resultant significant delays.
¢.)
the pipeline alternative is economically competitive
with treating local sources of groundwater in Matti~
tuck, Cutchogue, Greenport and Southold only if an
uncontaminated supply can be found in th~ MAgothy .
aquifer below the clay layer and above the saltwater
interface in eastern Riverhead. Preliminary data
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ERFI-Horth~st
indicates such a supply exists hut its extent and
yield needs to be verified with pump test informa.-
tion. To move further west in Riverhead into the
Peconic Vmlley where clean groundwater is known to
exist in m. ufficient quantity, is not economically
competitive with treating local sources of supply.
Preventative Measures
17.
This plan has identified numerous technical and financial
problems associated with providing water supply to areas
of the North Fork where groundwater is contaminated. Pre-
ventative measures must be undertaken in parallel with
recommendations 2 through 16 in order to eliminate or
minimize additional contamination. The following preventa-
tive measures are recommended:
a.) Expand the SCDHS observation well network and home
well sampling program.
Support the Cooperative Extension Service, Cornell
University and USDA research and education programs
directed to the homeowner and farmer relative to
usage, dosages, and timing of application of herbi-
cides, pesticides and fertilizers.
e.)
Support the testing
or'federal agencies
condition to use by
of agricultural chemicals by state
in the local environment as a pre-
the farm community.
d.) Prohibit or control the sale or use of products and
chemicals which threaten the groundwater resources.
e.) Control industrial, commercial and residential activi-
~ties which impact negatively on groundwater quality.
f.) Incorporate detailed water quantity and quality con-
siderations into rezoning and variance decisions.
g.)
Encourage water conservation through public informa-
tion programs and require water-saving fixtures in
new home construction.
Continue public information and education programs to
emphasize the fragile nature of the area's water supply
and to foster cooperation in the solutions to those
problems.
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