HomeMy WebLinkAboutSCWA - Public Water Supply Master Plan for TOS - 7/1992LEGGETTE, BRASHEARS & GRAHAM, INC.
PROFESSIONAL GROUND-WATER CONSULTANTS
MASTER PLAN FOR PROVIDING
A PUBLIC WATER SUPPLY TO THE
TOWN OF SOUTHOLD, NEW YORK
PREPARED FOR
SUFFOLK COUNTY WATER AUTHORITY
JULY 199~.-
I'tAY g 8 1998
WILTON
CONNECTICUT
ST. PAUL' TAMPA FISHKILL
MINNESOTA FLORIDA NEW YORK
RAMSEY
NEW JERSEY
EXTON SIOUX FALLS
PENNSYLVANIA SOUTH DAKOTA
ALBUQUERQUE
NEW MEXICO
NASHUA
NEW HAMPSHIRE
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LEGGETTE, BRASHEARS & GRAHAM, INC.
PROFESSIONAL GROUND-WATER CONSULTANTS
R. G. SLAYBACK
G. SIDNEY FOX
FR AN~K H. CRUM
MICHAEL R. BURKE
ROBERT LAMON1CA
WILLIAM K. BECKMAN
DAN C. BUZEA
July 28, 1992
JOHN NA$O, YR.
Mr. Edward Rosavitch, P.E.
Chief Engineer
Suffolk County Water Authority
4040 Sunrise Highway
Oakdale, NY 11769
Dear Mr. Rosavitch:
Enclosed for your use are twelve (12) copies of our report "Master Plan for
Providing a Public Water Supply to the Town of Southold, New York".
Bob Lamonica or I will be pleased to respond to questions or comments. We
hope this document is responsive to your needs.
Very tr~.:!y yours,
LEGGETTE, BRASHEARS & GRAHAM, INC.
RGS:skd
Enclosures
sufcon.ltr/92-34
MASTER PLAN FOR PROVIDING
A PUBLIC WATER SUPPLY TO THE
TOWN OF SOUTHOLD, NEW YORK
P~mred For
Suffolk County Water Authority
July 199'2
LEGGETrE, BI~_S~ & GRAHAM, INC.
Professional Ground-Water Consultants
72 Danbury Road
Willon, CT 06897
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MASTER PLAN FOR PROVIDING
A PUBLIC WATER SUPPLY TO THE
TOWN OF SOUTHOLD, NEW YORK
SUMMARY
The Upper Glacial aquifer in the Town of Southold contains a series of fresh-
water lenses separated by tidal creeks or inlets. Development of ground water for public
supply purposes is feasible in the lens areas, but individual well withdrawal rates will be
smaller than in western and central Suffolk County to minimize the threat of salt-water
inlxusion by lateral encroachment or vertical upconing. A widespread interstadial clay
offers greater protection from upconing on the North Fork than exists in the Montauk
area.
The largest present water use in the Town is for seasonal agricultural irrigation,
a largely consumptive water use, that is forecasted to decrease in future years. Public
water-supply usage will be mainly non-consumptive, as most of such usage is returned
to the ground by septic systems.
Six prospective public water supply well-field sites have been identified in the
western sector of the Town of Southold, with a preliminary yield potential of 3.2 mgd
(million gallons per day). Individual well yields are estimated to range from 200 to
625 gpm (gallons per minute). Each of the sites meets the Water Authority criterion for
tank overflow elevation at or near the well-field location. The chosen well sites are
mostly located on the southerly side of the fresh-water lenses, so as to minimize water
main distances to population centers which are mainly along the Peconic Bay coast.
Eventually, a transmission main could provide a continuous interconnection from the
Riverhead system to the Greenpofi: Water District, and perhaps eventually to Orient. A
prospective well site of modest yield potential (110 gpm) has been identified in the Orient
area.
Ground-water quality on the North Fork has been adversely impacted by
agricultural chemicals. Although it is possible that concentrations of such chemicals of
any given well site may not exec~'~_ drinking w~t_~ limits, the Water Authority should
plan on treatment for nitrate removal and for removal of pesticide, herbicide and
fungicide residues. Naturally-occurring iron and/or manganese concentrations may also
require water treatment.
LEGGt=i l~ BRASHEARS & GRAHAM, INC.
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INTRODUCTION
On May 5, 1992, the Southold Town Board adopted the following resolution:
WI~REAS, the Town Board is responsible for the health, safety and welfare of its
citizens; now, therefore, be it
Ri~OLVED that the Town Board of the Town of Southold hereby endorses a study of
a pilot plan by the Suffolk County Water Authority to provide public water to the people
in the area from the vicinity of the Riverhead Town boundary, South of the Long Island
Rail Road, up to the vicinity of Bay Avenue in the Mattituck area, subject to the Town
Board reviewing and approving the survey before it is released; and
BE IT FURTHER RF-qOLVED that the Town Board endorsea an initial study by the
Suffolk County Water Authority of water needs to serve Cutchogue and New Suffolk.
As a responsible provider of a safe and plentiful supply of water to over
one million people in Suffolk County, the Suffolk County Water Authority believes it is
prudent to anticipate the needs of the entire North Fork of Long Island so that, if the
need arises in the future, they are in a position to expand the initially envisioned pilot-
area system. As part of a coordinated effort to generate a Master Water Supply Plan for
the Town of Southold, the Authority requested that Leggette, Brashears & Graham, Inc.
(LBG), Professional Ground-Water Consultants, prepare a water availability study. No
specific attention has been given in this study to the area served by the Greenport Water
District, but this district could eventually be integrated into a townwide distribution
systenl o
The elements of the study include determination of the safe yield of the aquifers
underlying the town, estimation of current usage, determination of the optimum locations
for water-supply wells and storage facilities, and review of potential water quality in
future production wells.
POPULATION AND WATER USE
Population in the Town of Southold in 1990 was listed by the U.S. Census Bureau
as 19,836 persons. The LILCO estimate for Januar3, 1, 1991 was 19,831. The U.S.
LEGG~.I ~.~, BRASHEARS ~ GRAHAM, INC.
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Census data break out as follows by geographic areas according to "Census Designated
Places' (CDPs), which are not n~ly political boundaries.
SOUTHOLD TOWN U,S. CENSUS ESTIMATES
Geographic Area [ 4/1170 4/1/80
Laurel598 962 1,094
Mattituck 3,039 3,923 3,902
Cutchogue - New Suffolk 2,718 2,788 3,001
Peconic 835 1,056 I, 100
Southold 3,749 4,770 5,19'2
Greenpon West 1,682 1,571 1,614
(unincorporated)
Grcenport Village 2,481 2,273 2,070
(incorporated)
l~a~t Marion - Orient 1,240 1,511 1,534
Fishers Island 462 318 329
Totals 16,804 19,172 19,836
For the area of the Town of Southold west of the service area of the Grcenport Water
District, the first four listings - Laurel to Peconic - show a 1990 population of 9,097,
about 46 percent of the Town po[relation.
According to LILCO; the 1991 population estimate represents 8,229 households,
of which 3,774 are located in the four western CDPs; 46 percent.
The summer-season population is not so clearly known, but the North Fork Water
Supply Plan (NFWSP) provided estimates from the Suffolk County Planning Board of
a townwide summer increase of 19,760 in 1980, slightly more than double the year-round
population. These increases are dominated by second home and summer guest
populations, but also include motel and camping visitors.
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Per-capita water use in 1980 in the Greenport and Riverhead Districts was listed
in the NFWSP as 110 and 120 gpd (gallons per day), respectively. With a year-round
population of 20,000 in the Town of Southold, this transhtes to 2.2 to 2.4 mgd of
domestic water use. Present summer-soa,.on domestic water use would be expected to
be essentially double these values. Based on the water-supply experience in the Montauk
area, a growth in summer-vacation home populations could lead to seasonal water use
approaching four times the year-round rates.
For the four western CDPs, the Greenport and Riverhead per-capita usage figures
correspond to a demand of about half the townwide values. At present, these water
demands are being met by individual domestic supply wells, with the exception of the
Captain Kidd Estates water system which is operated by the Suffolk County Water
Authority.
The initial pilot-project plan announced by the Water Authority is to extend a
main from the Riverhead system along Peeonic Bay Boulevard east to Bay Avenue, with
the expectation of serving a substantial number of residences and businesses from the
Long Island Railroad/Route 25 area south to Peconic Bay. This area involves
approximately 800 property owners, and is known to have a history of private well
contamination with nitrates and/or pesticides, as well as high iron content. It is
anticipated that new well sources would be developed within about three yors and that
the initial pilot project would be expanded to the north and east.
WATER-SUPPLY AVAILABILITY
The hydrogeologic framework of the North Fork of Long Island has been studied
for the past 35 years by the United States Geological Survey and other concerned
agencies. The reference list of this report illustrates the coverage of the various studies.
Fresh-water supply in the Town of Southold is derived from local ground water
in the Upper Glacial aquifer. The Magothy aquifer contains salt water throughout the
North Fork. Available studi~s indicate that there is a surplus of shallow ground water
available for development, but that care must be taken to avoid unnecessary water-quality
problems related to agricultural land use and potential salt-water encroachment.
LEGG~-~ ~,'~ BRASHEARS & GRAHAM, INC.
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The most important recent finding concerning water availability is that there is
an areally extensive clay layer, previously only inferred, extending from Riverhead at
least as far east as Richmond Creek (NFWSP, 1980, Bohn-Buxton et al., in press). This
interstadial clay is present at approximately 50 feet below sea level in the
Laurel/Mattituck area, sloping northerly and easterly to about 100 feet below sea level
in Shore Acres/Wolfpit Lake and in Cutchogue. Its thickness varies from about 20 feet
in the west to as much as 90 feet in Cutchogue. Figure 4-1 from the ~SP is
appended to this report, a longitudinal section from Riverbead to Orient which shows the
relationship of this clay to the fresh-water lenses. There is also a lower interstadial clay
unit, but it is below the fresh-water/salt-water interface over much of the study area.
The presence of the upper clay unit limits the potential for upconing of salty water
beneath production wells.
As with most coastal ground-water resources, the key availability parameters are
aquifer transmissivity and individuni-well yield potential, volume of (fresh) water in
aquifer storage, and recharge rates. On this peninsula, which functions hydrogeologically
like an elongated oceanic island, a series of fresh-water lenses float on a large body of
underlying salt water, with lateral separation and salty zones between the lenses at the
major estuarine creeks. An overview of the more recent previous studies of the area
summarizes the available body of knowledge on these hydrogeologic parameters. As
with most hydrogeologic studies, the more recent reports are in part derivative of earlier
studies.
Hoffman - Bulletin GW-45
Hoffman (1961) of the United States Geological Survey, examined the specific
capacity - the yield divided by the drawdown - for 77 wells throughout Southold, and
found the following:
I.~,~ ~ Baa.Sim.~lts & Ga~n~/nc.
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Range in specific capacity Percent of wells
(gpm/ft!~)
40 or more 14
30 to 39 20
20 to 29 45
10 to 19 2O
~ than 10 I
J./ Gallons per minute per foot of drawdown.
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Thus, there is a reasonable expectation that properly designed and constructed wells will
have specific capacifes greater than 20 gpm/~ and probably more than 30 gpm/ft,
depending on local subsurface conditions.
From these data, Hoffman concluded that the transmissivity of the glacial deposits
*ranges from values somewhat less than 200,000 glxt per foot to values somewhat
greater". He further noted that the coefficient of permeability may range between 1,000
and 5,000 glxt per square foot.
With reference to storage, Hoffman utilized a specific yield of 0.17 and the
Ghyben-He~rg p~ciple to estim~'~ i~e torte ~re~h ~_"e,??-,,."~'- ?~.~e on the
mainland pan of the Town of Southold as 83,000 million gallons in April 1950. This
may be broken out into three segments:
West:
Mattituck Inlet to Hashamomuck
Inlet 70,000
Central:
Chapel Lane, Greenport to
Causeway, ~t Marion 6, I00
Orient 7,000
TOtal (rounded) ] 83,000
1_/ Million gallons.
LEGG~, s~. BRASHEARS & GRAHAM, INC.
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By far, the largest volume of fresh-water storage occurs in the west area, near Mattituck,
Cutchogue, and the Village of Southold. It should be noted that Hoffman did not
consider the storage in the part of the Town of Southold west of Mattituck Creek. Of
his grand total, only 2,000 million gallons, or 2.4 percent, was storage above sea level,
essentially in direct proportion to the Ghyben-Herzberg ratio (40: I).
Hoffman estimated average annual recharge to these three areas as:
west 8,6OO
Central ~0
1~ 1,100
Thus, in contrast to most of Long Island, the annual replenishment is a significant
percentage of the fresh-water storage, an impoCtant factor in water-supply planning.
In this light, Hoffman also looked at the annual recharge during a 3-year period
of minimum precipitation, in which only 30 percent of the precipitation became recharge.
Ama~al recharge
(mi~ MG MGD/mi:
West 29.2 5,750 0.54
Central 6.7 585· 0.24z'
East 4.7 715 0.42
Estimate reflects 2 mi~ area with surficial clay, assumed to have zero recharge.
Thus, in an area where fresh ground-water storage is limited, Hoffman estimates a
conservative drought recharge rate of about half the accepted average recharge rates for
Long Island.
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Crandall. USGS WSPol619-GG
Crandall (1963) questioned Hoffman's assumptions about evapotranspiration rates,
and calculated average recharge rates for four areas of the Southold peninsula (plus
two island-peninsulas not considered here), with reductions in parts of the Greenport area
to allow for local clayey sediments and paved areas. The west-central (B), central (C),
and eastern (D) areas were essentially identical to Hoffman's, but a western area was
added to the west of Matfimck Inlet and- extending about a mile into the Town of
Riverhead. His average recharge values for Area B were less than Hoffman estimated
for his West area to the east of Mattimck Inlet.
] Area I Annual recharge (MG)
A (West) 1,500
B (West-Central) 5,300
C (Central) 850
D (~a~t) 1,100
TOtal 8,750
Crandall noted that recharge may range from 25 to 35 percent of the total annual
precipitation in very dry or very wet years, respectively.
Crandall offered his own estimates for fresh-water storage based on a larger
specific yield of 0.22 and deductions for lill and clay units. His values, which are
substantially larger than Hoffman's, are:
Lr_x;~,g, Jr... Bv. nsar. nas& G~nM, I~c.
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Area I Fresh-water storage (MG)
A (West) 46,000
B (West-Central) 134,000
C (Central), 10,400
( ast) 10,400
Total 200,800
Nevertheless, Crandall's storage ~imates indicam that the largest fresh-water storage in
the Town of Southold occurs between M_..a~dtuck Inlet and Hashamomuck Inlet.
(~0mnrehensive Public Water Sun.Iv Study (CPWS-24}
The Comprehensive Public Water Supply Study for Suffolk County (CPWS-24)
(1968) by Holzmacher, McLendon & Murrell provided a fresh approach to ground-water
supply availability by proposing 'Permissive Sustained Yields" for specific areas within
the County. Permissive Sustained Yields was defined as "the maximum rate at which
water can be consumed perennially without bringing about some undesired result". In
effect, the estimates of Permissive Safe Yield began with area-specific recharge rates,
made reductions for near-coast areas outside the main water budget area, and made
further reductions based on an "optimum" position of the salt-water interface, including
considerations of drought. The CPWS-24 report also defined "Average Net Yields",
which were based on average-year recharge rates.
For Southold, the findings were:
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,~ Permi~'~ve P~Y per mi' Average
Sustah~ed of water Net Yield
Yield budget area (ANY)
(m~d) (m~d/mi~) (mgd)
We~t of Mattituck Creek 2 0.40 3.4
MnHtuck Creek to Hashamomuck 5.$ 0.35 10.4
Pond
Hashamomuck Pond to Orient Harbor 1 0.25 2.1
l:~.t of Orient Harbor 0.5 0.25 1.1
North Fork Water Suooly Plan - SCDH~;
The North Fork Water Supply Plan (NFWSP) (1983), prepared by
ERM-Northeast and Camp, Dresser & McKee for the Suffolk Counvy Department of
Health Services (SCDHS), offers lime new data rcla~l to basic aquifer parameters, but
much useful data on historical and projected wa~r use. For ground-wa~er availability,
this study reexamined and generally accepted the "Permissive Sustained Yields" from the
CPWS-24 report, but adjusted the water-budget areas slightly. Table 7-4 from the
NFWSP, a par~ of which is reproduced bctow, is a useful summary of the available water
budget, compared to the estima~l consumptive wa~er use in 1980.
LEGG,- l ~., BaASaT~aS & G~H~ I~¢.
SUMMARY OF WATER BUDGET ANALYSIS
(From Table 7-4, NFWSP)
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Zone pgrmissive sustained vleld Present Potentially
consump- available for
tive use future use
(mgd) (mgd/sq.mile) (mgd) (mgd)
I - Riverhead 29.4 0.7 4.7 24.7
2 -- Riverhead & West 5.6 0.4 3.9 1.7
Southold
3 - West Central 4.9~ 0.35 3.3 1.6
4 - Central 0.9x' 0.25 0.5 0.4
5 - l:~t 0.40~/ 0.25 0.47 0~
1._/ Since the underlying aquifers in these zones have insufficient storage, these values
are conservatively based on drought conditions and would be larger for a year of
average precipitation.
2_/ The zero enu3t indicates that the present consumptive use is approximately equal to
the permissive sustained yield in Zone 5 during drought conditions.
LBG Renorts
LBG has prepared several reports on the Southold area for the Water Authority
dealing with "Facwrs Affecting Water Supply Development" (1985) and site-specific
reports (Mill Lane-l~89, Oregon Road-1991, Laurel Lake-1992). For these reports, the
CPWS-24 "Permissive Sustainable Yields" have been adopted as the most conservative
values for water-supply planning purposes~ and site-specific data have been utilized for
well-field planning.
The "Factors" reports dealt with the historic fluctuations of the fresh ground-water
mound in the area between Mattituck Inlet and Richmond Creek, in effect the west-
central, Area B, or Area 3 region of previous studies, and theoretical aspects of salt-
Inc.
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water upconing beneath a pumping well as related to yield and positioning of the well
screen, as well as general well-field spacing.
The three site-specific reports provided preliminary yield-potential estimates
ranging from 175 gpm at Mill Lane, to 350 gpm at Oregon Road, to 625 gpm at Laurel
Lake. In each case, consideration was given to vertical upconing and lateral encroach-
ment of salt water as the potential limiting parameters.
WELL-FIELD SITE SELECTION CRITERIA
It is evident that salt-water encroachment, vertically and/or horizontally, is the
practical limiting factor for public supply well fields. In practice, it has been found that
lateral encroachment is the more limiting factor for well or well-field yield in Southold
when theoretical performance is evaluated. As was determined earlier on the South
Fork, this means that the optimum locations for ground-water development are along the
central spine of the North Fork, where fresh ground-water mounds or lenses occur
between the major creeksYtidal inlets, roughly coincident with the Long Island Railroad
track. This area affords the greatest aquifer thickness and the greatest distances from
salt-water bodies. However, there are other factors which have to be considered in
Southold.
Pouulation Centers
The primaxy population centers are located along the southern portion of the town
adjacent to Peconic Bay, and also along Mattituck Creek. It therefore becomes
inefficient to construct well fields in the interior because of water-main length and
excessive pressure losses through the transmission pipes. The well-field site selection
process included placing wells in reasonably close proximity to population centers.
Storaee Tanks
Another factor is storage tank placement. In order to be able to integrate the
Southold system with the Riverhead system, as well as other Authority systems, the tanks
must have an overflow elevation of 185 feet above sea level. The tallest tanks the
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Authority constructs are 150 feet, which means that they must be located at 35 feet above
sea level. The 35-foot contour in the western part of the Town of Southold, shown on
plate 1, is approximately coincident with a water-table elevation of 4 to 5 feet above sea
level on the southerly side of the fresh-water mound. At this elevation, the prospective
well sites are sufficiently removed from salt-water bodies to minimize lateral salt-water
intrusion potential. All of the six well-field sites in western Southold could accommodate
a tank at elevation 35 feet above sea level onsite or in near proximity. A detailed review
of storage needs is beyond the scope of this study but is a potentially important factor in
an area with high seasonal weekend usage.
F h-W r M und
The LBG report of March 1985 outlined the normal and extreme drought year
(1966) water-table mound centered on Cutchogue Station, between Mattituck Creek and
Richmond Creek. A number of prospective production well-field locations have been
considered essentially between the normal +4- and +5-four water-table elevation
contours. These general locations have been chosen because they ~ downgradient of
the ground-water divide, sufficiently distant from tidal water, have a relatively thick
fresh-water lens, a~e sufficientiy separated to avoid undue mutual drawdown interference,
are reasonably close to population centers and Main Road (Route 25) and, in a
preliminary way, a~e in re-'oas where property may be readily available to the Water
Authority.
Previous studies by LBG show that at water-table elevations of 4 feet above sea
level, well yields as high as 700 gpm can be a~hi~ved without inducing upeoning of salt
water (LBG, 198fi). Thes~ calculations were completed without cunsiderafion of the
areally-cxtensive interstadial clay layer, which would be even more protective of high-
yield wells.
Based on the above factors, six well-field locations have been selected, as shown
on plate 1. The anticipated long-term yields of the well fields, also shown on plate 1,
are based on a recharge rate of 0.5 mgd/m~, and the indicated circles around each well
site symbolically represent the equivalent recharge area. The actual zone of capture for
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each well field would have a parabolic shape centered on the wells and widening up to
and, in some cases, beyond the present ground-water divide. As any site is tes~l and
developed, site-specific zone-of-capture modeling should be used to define the actual zone
of recharge capture. The total selected well*field network would have a combined
sustained capacity of 3.2 mgd, sufficient yield to supply a population of about
30,000 people. This is well in excess of the population projections for the entire Town
of Southold to the year 2020.
It is important to recognize that short-duration .~msonal pumpage substantially
greater than the year-round rated capacities may be accommodated. The presence of
upper interstadial clay in western Southold implies that seasonal upconing of saline water
will be less of a limiting factor than on the South Fork.
Sources of Known or Potential Contamination
The most recent inventory of land disturbances that may involve potential
hazardous waste/storage facilities is the Cornell University CLEARS study for the
SCDOHS, in which a county-wide inventory of potential waste-disposal sit~ was made
by detailed analysis of aerial photographs for 1962, 1978 and 1984. Such features as
dumps, landfills, pits, lagoons, barrels or drums, mined area~, disturbed land and above-
ground tanks were identified, and changes associated with these sites over the photo
histo~-y were described. Where I~F, inent, CLEARS information for file vicinity of
pwposed well-field sites is discussed below in the section on each proposed well-field
location, and the mapped sites are shown on plate 1.
Competition With Irri~ation
As can be seen in table 7-4 from the NFWSP (page 11 of this report), agricultural
irrigation is the largest consumer of water on the North Fork. E~timates of the past
irrigation pumpage have been given in previoua report~, vary considerably from wet to
dry year, and are considered unreliable by local agricultural experts.
L£GG~ a~., BIO,~IF. AI~ & GRnItAM, I~C.
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A windshield survey of thc North Fork was conducted in/one 1992 for a first-
hand understanding of the active farming and irrigation activities, eg~ecially in relation.
to prospective public water supply well sites.
In the Town of Southold, there appears to be considerable agricultural diversity,
with the historic dominant potato acreage giving way to sod and wine grapes, and a large
acreage still in vegetables and berries. Table 7-3 from the NFWSP, reproduced below,
gives estimate~ of crop acreage and annual water consumption in 1980 ba~d on estimates
by the Suffolk County Cooperative Extension Service.
IRRIGATION REQUIREMENTS FOR CROPS GROWN
ON THE NORTH FORKv
(From Table %3, NFMSP)
Crop type Acreage Irrigation requiremenL~-
(g:dlons per acre per year)
Potatoes 12,000 125,000
Mixed vegetables 4,000~ 205,000
Cabbage and Cauliflower 3,500 205,000
Rye 2,000 --
Nurser3, stock 2,000 165,000
Pastures 1,000 20,000
Sod 1,000 245,000
Sweet corn 800 125,000
Fruit trees 6(~0 125,000
Grapes 350 40,000
Greenhouses 25 815,000
TOTAL 27,275· 140,000
(weighted average)
l./ Communication with D. Fricke et al. from Suffolk County Cooperative Extension
Service.
2-/ Peppers, spinach, beans.
~/ All figures rounded.
4_/ Acreage was estimated.
l
By contrast, a 1991 estimate for all of Long Island for 1991 from the Farm Bureau
shows only 7,500 acres in potatoes, 2,450 acres in cabbages and cauliflower, but with
substantial increases in nursery stock, sod and grapes.
Irrigation practices vary widely by crop and individual preferences, but mainly
involve moveable sprinklers, with some trickle-irrigation in nursery stock areas. The
'rule of thumb' is that most crops n__~d_ an inch of natural or irrigation water per week
during their growth cycle. In a typical year, sod requires about double the water that
potatoes need because of the growth cycle, whereas wine grapes are rarely irrigated
except in the initial season of planting until the deep roots are set. A representative of
the Soil Conservation Service offered his opinion that most crops in the Town of
Southold are under-irrigated because of the lack of sufficient equipment and labor, and
that the grape crop could be improved by periodic irrigation.
In June 1992, a fairly sizeable acreage was in hay or lying fallow, with some
areas showing 'old field progression' to woody plants. Numerous 'for sale" signs were
evident on inactive and on some active farms. As housing displaces farms, the
consumptive use of ground water will decrease. Whether homes are supplied by
individual wells or by public water supply, the major part of domestic water use will be
returned to the ground by septic systems. Most of the previous reports on the North
Fork forecast a long-term reduction in commercial agricultural activity in the future,
following patterns from the west. If reaiizea, this will result in less consumptive use of
ground water.
A working paper by the 1991 US/UK Countryside Stewardship Exchange Project
found that there were 470 parcels of land of 10 acres or larger in the Town of Southold,
comprising 13,500 acres. Active commercial farms, 84 in number, involved ownership
of only 3,670 acres. Retired farms comprised 2,533 acres. Substantial acreage, much
in sod, was leased land, not included in the active farm list. A total of 1,100 acres of
farmland in the Town have reportedly had their development rights sold.
LEGG~.~ ~, BRAS~a~S & GmmAM, i~C.
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PROPOSED WI~LL-FII~.LI~ LOCATIONS
Site A
Site A is a farm site in an area presently used for cabbages and potatoes and with
wine grapes, more potatoes and a small horse farm in the immediate area. For the
present, there would be moderate competition for the available water for irrigation
purposes, and only minor potential for interference with domestic supply wells. The
preliminary yield potential of this site is estimated as 0.5 mgd.
Site B
Site B is in unoccupied woodlands directly to the east of the Laurel Lake tract.
Nearby farmland is lying fallow; there is some active potato fanning to the west and
southwest. Competition with irrigation is deemed minor. There is minor potential for
interference with domestic supply and commercial wells within the Laurel Lake
community, the Camp Malloy area and along Main Road (Route 25). The preliminary
yield potential is estimated as 0.9 mgd. An issue that will need to be addressed during
testing will be potential impacts on fresh-water wetlands about 1,000 feet to the north of
the site.
There is an abandoned sand and gravel pit to the east of Laurel Lake near the
prospective well site. It has a hummocky appearance that looks like sand and gravel was
dumped in, perhaps to cover something, rather than a typical mined-out appearance. No
diz~ct evidence of dumping was observed. This site should be checked out by test
borings and a monitoring well during testing for a production well siM. The CLEARS
study makes note of this site and another gravel mining site south of Main Road near
Bray Avenue. In addition, an industrial site between Main Road and railroad tracks has
a history of above-ground storage tanks, scattered waste and soil mounds. One or more
monitoring wells would be warranted in this direction.
Site C
Site C is in farmland presently in use for vegetables and near some fallow land.
Potatoes are grown to the west, wine gropes to the south, and more fallow land lies to
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the east. At present, there is moderate seasonal competition for the local ground water
for irrigation, and some potential for interference with domestic supply wells along Main
Road (Route 25). The preliminary yield potential is estimated as 0.5 mgd.
Site D
Site D is presently a Christmas tree farm. Wine grapes and beans are being
grown to the west and northwest. The Town of Southold landfill is located 1.2 miles to
the north-northwest, on the northerly side of the ground-water divide. Competition with
seasonal irrigation water use appears light, but some potential for interference with
domestic supply wells along Main Road (Route 25) and nearby side streets. The
preliminary yield potential is estimated as 0.5 mgd.
Site E
Site E is mainly in a wine-grope area, mostly associated with a single vintner.
Competition with seasonal irrigation is presently light and the potential for interference
with domestic wells is slight. The preliminary yield potential is estimated as 0.5 mgd.
Site F
Site F is in a primarily residential and wooded area. Directly to the northwest
is a recharge basin/pond which has wetlands characteristics, and directly across Middle
Road is a gasoline station. The site is too small to accommodate a storage tank but land
1,000 to 2,000 feet to the northeast on the north side of Middle Road, near the power
line right-of-way, may be suitable. There is little to no competition with irrigation
supplies, but some potential for interference with domestic supply wells. A 1989 test
well at this site showed excellent water quality, and pore-water samples from the
inte~stadial clay showed fresh water to more than 100 feet below the production zone.
The preliminary yield potential is estimated as 0.25 to 0.30 mgd. A public water-supply
permit has been issued for two wells at this site with an authorized withdrawal rate of
288,000 gpd (gallons per day).
LEGG~..~ ~,':., BRASHF_.ARS &: GV.~AM, I~c.
Once suitable properties are located for well installation, a testing program would
be initiated. At each site, a test well would be installed and a controlled pumping test
run to determine the zone of contribution. The tests would utilize existing or newly-
installed monitor wells to determine water-level drawdowns at specific distances from the
well fields. The final recommended well yields would be based on the aquifer testing.
The initial development is planned for the Laurel Lake area. It is anticipated that
this Well field will be capable of supplying water to the communities west of Mattituck
Creek along Peconic Bay, as well as most of Mattituck.
In addition, the present investigation has included consideration of prospective
well sites both east and west of Mattituck Creek and in Orient. No consideration has
been given to the Village of Greenport which operates its own public supply system
supported by wells.
Orient Area
Plate I also shows the much smaller and lower ground-water mound in Orient,
with the location of a prospective well-field site. Based on Table 7-4 of the NFWSP
(page 11 of this repori), thc Permissive Sustained Yield of this area is already over-
subscribed, mainly by agricultural pumpage. Considering that both the agricultural and
residential consumption peak during the same months, and the small volume of local
fresh ground-water storage, it appears likely that increases in pumpage would likely lead
to salt-water encroachment, especially in drought years. A local source of public water
supply by shallow wells might be feasible if a significant volume of agricultural pumpagc
is retired. A rectangular manmadc pond about a half mile to the east at the headwaters
to the wetlands was identified by the CLEARS study. The 1978 and 1984 photos showed
the pond being filled in with material including miscellaneous waste. Thc estimated yield
potential of this site is about 0.15 mgd.
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GROUND-WATER QUALITY
Ground-water quality in the Town of Southold has been widely degraded by
leaching agricultural chemicals. Heavy fertilizer usc has caused elevated nitrate levels,
commonly exceeding the drinking water standard of 10 rog/1 (milligrams per liter) of
nitrate-nitrogen. Concentrations of residues of aldicarb and other pesticides and
fungicides also commonly exceed drinking water limits. Naturally-occurring dissolved
iron and, to a lesser extent, manganese are also commonly esthetic nuisances for private
well owners. Where present above the Secondary Maximum Contaminant Levels in
public water-supply wells, treatment for removal would be required and would be a
benefit to customers.
Well-site selection can minimize the concentrations of agricultural chemicals.
Initial sampling results from the Mill Lane test well in Peconic indicated excellent water
quality, but sustained high-yield pumpage at any site will tend to draw in water from
laterally-remote areas, and to draw water from the upper part of the water table where
surficial chemical impacts tend to be concentrated. Any well in the Southold area should
be expected eventually to show impacts of agricultural chemicals, although not
necessarily in excess of drinking water standards. It would be prudent to plan on water
treatment for nitrate and pesticide/herbicide/fungicide removal and for iron and/or
manganea~ remova~ at each well fic~..
CONCLUSIONS AND RECOMMENDATIONS
1. There is sufficient flesh ground water in the Town of Southold to support
the expected future population growth into the early part of the next century.
LEGGt. i ,~ BRAsnva, as & GRAHAM, I~C.
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2. The expec~l future reduction in commercial agricultural activity will
reduce the consumptive use of ground water, resulting in a more favorable hydrogeologic
budget. Ground water used for domestic water supply is largely returned to the ground
by septic systems.
3. Ground-water quality in the Town of Southold has been impaired by
residues of agricultural chemicals. Although any well site may initially show satisfactory
water quality, some water-quality degradation over time should be expected. Treatment
for nitrate and/or pestieidedhe~bicidedfungicide residue removal and for iron and/or
manganese removal should be planned for any public water well field in the Town. Over
the very long term, reduced agricultural activity should result in some ground-water
quality improvement.
4. Six well-field sites have been identified in the western part of the Town,
from the Riverhead border to the hamlet of Peconic. These sites have individual
projected yield potentials of 200 to 625 gpm, and an aggregate estimated yield of
3.2 mgd. Tank locations that would meet the Authority's elevation criterion are available
at or near each well site. The well-field and umk sites have been situated so as to be
reasonably close to population centers that may want public water-supply service. The
ultimate distribution system would likely fie into the Greenpon Water District, providing
additional back-up capacity for that system.
5. The ground-water resources in the Orient area appear to be fully
subscribed by domestic and agricultural usage. If agricultural acreage is retired, a small
local well field may be feasible.
L£G.a, ~. B~rr_~as & GannA~ Inc.
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6. As with any Water Authority exploration program, a full-scale testing
program should be conducted at any proposed well-field site to ascemin the hydraulic
characteristics of the subsurface material, the depth of the salt-water interface, the
stratigraphy, the water quality and any potential impacts of water-supply development.
skd
July 28, 1992
southold, rpt]92-34
LEGGETrE, BRASHEARS & GRAHAM, INC.
Robert Lamonica, CPG
Vice President
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SUMMARY ......................................... 1
INTRODUCTION ....................................... 2
POPULATION AND WATER USE ............................ 2
WATER-SUPPLY AVAILABILITY ........................... 4
Hoffman - Bulletin GW-45 5
Crandall USGS WSP-1619-GG 8
Comprehensive Public Water Supply Study (CPWS-24) ........... 9
North Fork Water Supply Plan - SCDHS .................... 10
LBG Reports ..................................... 11
WELL-FIELD SITE SELECTION CRITERIA ..................... 12
Population Centers .................................. 12
Storage Tanks ..................................... 12
Fresh-Water Mound ................................. 13
Sources of Known or Potential Contamination ................. 14
Competition With Irrigation ............................ 14
PROPOSED WELL-FIELD LOCATIONS ........................ 17
Site A ......................................... 17
Site B ......................................... 17
Site C ......................................... 17
Site D ......................................... 18
Site E ......................................... 18
Site F ......................................... 18
Site-Specific Testing ................................. 19
Orient Area ...................................... 19
LEGGr~ ar.., Bv~ar~v.s &Gm, Ha.~, L'qc.
TABLE OF CONTENTS
(CONTINUED)
GROUND WATI~R QUALITY 20
CONCLUSIONS AND RECOMMENDATIONS .................... 20
REFERENCES
APPENDIX
PLATE
FIGURE 4-1 FROM THE NFWSP
pI~I:.I.IMINARY WATER-SUPPLY PLAN
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REFERENCES
Baler, J. H. and Dennis Moran, 1981, 'Stares Report on Aldicarb Contamination of
Groundwater as of September 1981", Suffolk County Department of Health Services.
Baler, J. H. and S. F. Robbins, 1982, "Report on the Occurrence and Movement of
Agricultural Chemicals in Groundwater - North Fork of Suffolk County', Suffolk
County Department of Health Services.
Bohn-Buxton, Debra E., Herbert T. Buxton and Valerie-ann K. Eagen, in press,
'Ground-Water Flow Patterns and Travelfimes on North Fork, Long Island, New
York, in Relation to Aldicarb Contamination", United State~ Geological Survey.
Crandall, H. C., 1963, 'Geology and Ground-Water Resources of the Town of
Southold, Suffolk County, New York", United States Geological Survey, Water
Supply Paper 1619-GG.
ERM-Northeast Engineers, P.C. and Camp, Dresser & McGee, 1983, "North Fork
Water Supply Plan, Suffolk County, New York", prepared for Suffolk County
Department of Health Services.
Hoffman, John F., I961, ~Hydroiogy of the Shailow Ground-:~Vater Rcsctwoir
Town of Southold, Suffolk County, Long Island, New York', United States
Geological Survey, Bulletin GW42.
HoLzmacher, McLendon & Murrell, 1970, "ComprehensiVe Public Water Supply
Study, Suffolk County, New York, CPWS-24.
Iensen, H. M. and Julian Soren, 1974, ~Hydrogeology of Suffolk County, New
York', United States Geological Survey, Hydrologic Investigations Arias HA-501.
Leggette, Brashears & Graham, Inc., 1985, 'Factors Affecting Water-Supply
Development in the Southold Area, Long Island, New York', prepared for Suffolk
County Water Authority.
LEGGt..s l~, Bm,sm & GRAHAM, INC.
-24-
Leggette, Brashears & Graham, Inc., 1989, 'Hydrogeologic Evaluation of the
Richmond Creek Subdivision Property, Mill Lane, Peconic, New York', prepared for
Suffolk County Water Authority.
Leggette, Bra.shears & Graham, Inc., 1991, 'Hydrogeologic Evaluation of the
Property at Oregon Road, Oregon Hills, Town of Southold, New York', prepared for
Suffolk County Water Authority.
Leggette, Brashears & Graham, Inc., 1992, 'Potential Land Acquisition, Laurel, New
York', prepared for Suffolk County Water Authority.
Luscynski, N. J. and J. F. Hoffman, 1951, 'The Water Table as of April 1950 in
Southold Township, Suffolk County, Long Island, New York', United States
Geological Survey, Open-File Report.
McClymonds, N. E. and O. L. Franke, 1972, 'Water-Transmitting Properties of
Aquifers on Long Island, New York", United States Geological Survey, Professional
Paper 627-E.
Soren, Julian and W. G. Stelz, 1984, "Aldicarb-Pesticide Contamination of Ground
Water in Eastern Suffolk County, New York', United States Geological Survey,
Water Resources Investigations Report.
Suffolk County Water Authority, 1990, "Southold Watershed Management Plan:
Evaluation of Proposed Alvah's Lane Wellsite, Hamlet of Cutchogue~.
APPENDIX
FIGURE 4-1 FROM THE NFWSP
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ZONE I i ZONE ?- _ , ZlNE ;5 ZONE 4.
SOUTHOLD
LINE ~b~q~.O BOUNDARY
HAS;
WATER TABLE ; ;I TABLE F 0
LEV
SEA
CLA~ AND CLAY ; ~ ~LA~ )
2?5-
300.
325-
350.
375'
400'
425
FRESH WATER TO BEDROCK
ZONE 5
DAM
~NAL
TEST WELL
GLACIAL
Figure 4-1
Geologic Cross - Section
9! 4 ....
APPR~)XIMATE AREA OF CAPTURE '
APPROXIMATE 5 FOOt: WATER TABLE CONTOUR
-~PPROXIMATE
0 2000
SCALE IN FEET
SUF
MD
D
T
X
XL
G
P
LEGEND_
PROPOSED WELl- LOCATION
MINED AREA
MINED AREA-DUMP
DUMP
ABOVEGROUND TANK
DISTURBED LM~D
DISTURBED LAND-LANDFILL
LAGOONS
POLK COUNTY
TOWN OF
~NATER AUTHORITY
SOUTHOLD
PRELIMINARY WATER SUPPLY PLAN
DATE -- REVISED PREPARED BY:
-- t LEGGETTE, BRASHEARS & ~RAHt2vl, INC.
--t -- I Professional Ground-}Ta~er Consultants
~ ~ 72 Danbury Road
-~ I '~ ~ilton, CT 06897
49
APPROXIMATE ~V.~LL FIELD
]Jame~port
0 FEET
5
APPROXIMATE AREA OF CAPTURE
9
5
3
· APPROXIMA'J~E 5 FOOT WATEF~ ,.TABLE Col~rI'OUR "
t3
Jc
LEGEND
PROPOSED WELL LOCATION
.\
Neck
Bay
L
Har, bor
CUTCHOG[fE HARBOR
0 2000
SCALE IN FEET
t3 /
SOUTH
DRAWN: CHECKED:
M.R.V.
, 22
/5
SUFFOLK COUNTY
TOWN OF
PRELIMINARY
DATE REVISED
WATER AUTHORITY
SOUTHOLD
WATER SUPPLY PLAN
BY.'
LEGGETTE, BRASHEARS & GRAHAM, INC.
Professional Ground-Fater Consulfants
72 Danbury Road
Wilton, CT 06897
(203) 762-1207
PLATE: 1 OF I
%
THIS IS A RECORD DRAWING:
OF WORK AS CONSTRUCTED:
,, SU FOZ ' c001,77'Y'
REVISIONS
DESCRIPTION
DATE
DESCRIPTION
· APPROVED:
WALTER, C, HAZLITT, ~EXECUTIVE DIRECTOR,
pROF,
ENGINEER
LIC, NO. O~ ;7585
$,UFFOLK COUNT'Y WATI~:I{ AUTI1ORITY
D..p~,.TM~:,,r.r...,,,......
E~NEE~NG,
SUNRISE HIGHWAY AT POND RO~
' , OA~A~ L.I., N Y '
THE EDUCATION LAW
AN
DRAWINGS ANDIO~
UNLES~
PROFESSIONAL ENGtNIEEI
NOTE
AND/OR IN 3HE SPECIFICATIOi~IS.