HomeMy WebLinkAboutSCWA Water Treatment Alternatives 2002
-,-
y5MPAZ-- Sf1Wp HLE
.
Suffolk County Water Authority
Water Supply Treatment Alternatives For Southold
Revised 9/24/02
.
.
.
The Suffolk County Water Authority is in the process of evaluating various
alternatives associated with providing a safe, long term and reliable source of water to the
North Fork of Long Island. Currently the SCW A owns and operates 17 well fields in this
distribution area. Ofthe 17 well fields, 10 now have detectable levels of the contaminant
Perchlorate in the welles) on that site. Perchlorate is a constituent of some fertilizers and
it is assumed that the use of this material on farmland and residential properties on the
North Fork is the likely source of the contamination. The current standard in NYS for
Perchlorate in drinking water is 15 parts per billion, but it is anticipated that the standard
will be lowered in the not too distant future to a level below the current levels
experienced in the SCWA well fields. If the standard were lowered tomorrow,
approximately 3500 GPM of the total 5000 GPM well field capacity would be rendered
unusable.
As a responsible water supplier, SCW A must now work diligently to develop a
long-range plan that addresses the various options associated with treatment of the water
supply. The plan must take into account the present and future water needs of the North
Fork along with any other external factors that could impact this decision. This
document outlines the alternatives associated with water supply treatment only. Other
alternatives are being developed that will examine the cost of water importation which is
a possible alternative to treatment. It is anticipated that once all options have been
identified, the SCW A Board will adopt an updated supply plan for the North Fork.
Treatment Alternatives:
.
1. Ion Exchange Resin Technology with On Site Regeneration- Ion exchange
resin systems for the removal of Nitrate contamination have been in use for many
years. This same technology is applicable for removal of Perchlorate. The
technology relies on filter media that consist of synthetic beads that are coated
with anionic gel. When raw water passes through the filter media, the
contaminant in the water (Perchlorate) exchanges with a chloride ion that has
been deposited on the media during what is referred to as a regeneration cycle. In
effect, as the water flows through the filter, the media gives up chloride ions and
removes perchlorate ions. As this process goes forward, eventually all of the
resin becomes spent or in other words has given up all of its chloride ions and
there is no more opportunity for the ion exchange process to occur. At this point
it is necessary to regenerate the resin. This is done by shutting down the filter,
passing a salt water or brine solution through the filter media, which in effect
flushes all of the perchlorate off of the resin and replaces it with new chloride
ions. What is left after this process is a freshly regenerated filter along with a
volume of spent brine that is a mixture of saltwater and concentrated perchlorate
waste. This waste amounts to approximately .2 percent of the total system flow
and must be disposed of. The typical disposal method is to truck the waste to the
nearest sewage treatment plant where it is properly treated and discharged into the
ocean or Long Island Sound. For the purposes of this analysis, it was assumed
that the spent brine would be disposed of at the Bergen Point Sewage Treatment
Plant. A potential cost saving alternative to this method of disposal is through the
.
.
use of deep underground injection wells. In this alternative scenario, a deep
injection well would be drilled on each site to a depth where salt water was
encountered. Brine waste from the treatment systems would then be disposed of
down the well. The brine has salinity that is similar to seawater and as such, it
should be relatively easy to obtain a permit from the NYSDEC for this type of
disposal. The waste however also will contain concentrated perchlorate, nitrates
and sulfates that were removed by the treatment system. The presence of these
contaminants may prevent the issuance of a permit for underground disposal.
Currently SCW A is in discussions with the NYSDEC regarding the underground
disposal option.
In order to treat a continuous stream of contaminated water it is necessary
to have multiple filter vessels installed so that at any given time, one vessel will
be filtering while another is in the regeneration mode. This continuous process
has been developed by a few manufacturers and is rapidly becoming the preferred
method of plant operation.
.
A summary of the capital costs associated with the installation of well
field based perchlorate treatment systems is shown on Table II. The costs are
self-explanatory and assume that all work will take place on SCW A owned
properties using a modular approach whereby the systems are delivered to the site
in containerized units that can be altered aesthetically in the field to suit the
surrounding neighborhood. The remainder of the costs includes engineering and
miscellaneous SCW A labor associated with the construction and initial start-up of
the filtration systems. The capital cost per gallon of treated water varies
depending on the capacity of the filter. The larger the flow, the more economical
the filter installation would be. The capital cost per GPM for the treatment
systems at sites such as Main Bayview and Evergreen drive are approximately
four times that of the larger sites. It is therefore most advantageous from a cost
standpoint to treat as large a flow as possible due to the relative economy of scale
associated with the treatment process.
The operation and maintenance costs associated with installation of the
treatment systems are shown on Table 12. They include costs that vary with the
amount of water processed (variable O&M) such as the continuing purchase of
salt for the production of regeneration brine and the cost of spent brine disposal.
They also include the fixed O&M costs such as extra operator labor and water
quality sampling that will be necessary to support these systems.
2. Ion Exchange Resin Technology with Off Site Disposal- This modified
version of Alternative I above utilizes the same type ofresin and ion exchange
process except that the volume of resin would be significantly larger and the resin
would be disposed of off site after it has become spent. The advantage to such a
system is in its simplicity. There would be no regeneration ofresin, brine storage
or waste storage on the well field.
.
.
The sew A is currently in the process of piloting a treatment system whereby
ten-foot diameter filter vessels that are normally used for granular activated
carbon are filled with ion exchange resin. The filters will be installed on wells
that have perchlorate contamination. The filter effluent will be carefully tested to
determine the actual volume of water that can be treated before the resin is spent.
Once this volume is determined, sew A will be in a position to evaluate the costs
associated with operating such a system.
.
3. Membrane Filtration - Membrane filters are commonly used today to filter out
a variety of contaminants. Reverse osmosis filters are considered to be an
acceptable method of removing nitrates and perchlorate. The drawback to the use
of this alternative is the relatively high waste stream (approximatelv 15 percent of
system flow) that results from the operation of these treatment systems. This
higher waste production results in higher operation and maintenance costs due the
increased cost of disposal. In addition to the high volume waste stream, reverse
osmosis treatment systems require more energy to operate due to the high higher
head loss associated with "pushing" the raw water through the membrane
elements during filtration. Depending on the raw water quality, this extra head
loss can be so significant that it becomes necessary to install booster pumps to
develop the pressures necessary to create the required flows. In sew As
experience with using this technology at the East Lake Drive well field in
Montauk to remove elevated levels of chloride it was necessary to boost the filter
inlet pressure to 150 PSI in order to move water through the membrane at the
desired flowrate.
There are currently under development membrane filtration systems that
employ multiple stage membranes that theoretically reduce the total waste stream
and also have lower head loss. If these refinements were possible, membrane
filtration could become a viable well field treatment system. This treatment
alternative has additional benefits in that the membranes have the potential to
remove a wide range of other contaminants that might develop in the future.
More investigation needs to be done to develop cost estimates for the installation
and operation of membrane systems.
.
4. Desalination of Seawater Using Membrane Filtration - Desalination of
seawater has been in use for many years and while expensive, it very often
represents a viable method for producing high quality drinking water when there
is little fresh water available. The technique utilized in desalinating seawater is
similar to membrane filtration in clean water applications except that due to the
higher chloride concentrations found in seawater, the water must be highly
pressurized in order to pass through the membrane. Many membrane based
desalination systems require pressures in excess of 1000 PSI in order to operate.
The energy necessary to develop and maintain this pressure is extremely large and
as can be seen on Table 12, the resulting operational costs are quite high due to
the cost of the electric power required to run the required booster pumps. A
typical treatment system rated at 250 GPM would require a 500 HP electric pump
.
.
.
.
to create the pressures and flow needed to operate. In addition to the operational
costs, the capital costs of this system are also significantly higher than an ion
exchange system and are shown in Table 12.
5. Desalination of Brackish Water Using Membrane Filtration - In most areas of
the North Fork, the underlying saltwater interface below SCW A w<<lls is quite
shallow. For this reason, well capacities are significantly smaller. Larger wells
would easily induce saltwater upconing and result in chloride contamination. In
several parts of the country, coastal communities have endeavored to pump wells
that have been impacted by salt-water intrusion with the understanding that this
water would be easier to treat than seawater. In the case of the North Fork, the
continued pumping of wells that have been impacted by saltwater intrusion has
the potential to impact other private and agricultural wells and would require a
special permit from the NYSDEC. It is anticipated that the NYSDEC would be
reluctant to issue such a permit in light of the fact that there are other alternatives
such as wellhead treatment or water importation available to the SCW A.
6. Point of Use Filtration - Point of use filtration refers to the installation of under
the sink style reverse osmosis filtration systems. Under this alternative the
drinking water in a particular household would be filtered to remove perchlorate
with the rest of the water left in violation of the drinking water standard. SCW A
currently has 21 point of use filters in service to treat for the removal of nitrates.
In these homes. the SCW A laboratory has confirmed the effectiveness of reverse
osmosis filters in removing perchlorate. Large scale deployment of point of use
filtration would involve significant capital cost in addition to routine maintenance
which could be problematic due to the need to access customer premises to
perform such operations. The cost of this alternative needs to be examined more
carefully.
.
DRAFT
.
TABLE 11. NORTH FORK PERCHLORATE REMOVAL TREATMENT SYSTEM, CAPITAL COST ESTIMATE SUMMARY TABLE
GENERAL WELL INFORMAnON TREATMENT SYSTEM CAPITAL COST ESTIMATES
Ay, . Site Well Water Quallt Ita\ Approx. Avg. Avg. Daily Well Avg. Yearly Waste Brine Avg. Yearly Filtration System Exterior Siding Brine & Waste Installation & Sub Total Site Engineering and Total Estimated
Sulfate neat" Hours! day Field Production Flow Rate Waste Brine Estimated Costs and Roof on Concrete Tank Yard Piping Electrical Mise-Site Treatment Authority Labor Contingency (20%) She Treatment Capital Cost
Pump Station Weill's Perchlorate Nitrogen as (~~~ Chloride Flow wells Treatment Sys. W.... Containment Upgrades ....gpm
(ugll) N (mgll) (mgll) gallons/day (gal.) (gpm) (gals) (b,c) W.... Costs (20%) Costs
(m ) (gpm) operated Enclosure Costs
ckerly Pond 1,2 4 8 65 10{) 040 66 334,250 122,001,250 17\' 'li:>YF $ 1,200,000 $ 75,000 $ 35,000 . 25.000 $ 50,000 . 40,000 $ 125,000 . 1,550,000 . 310,000 $ 372,000 $ 2,232,000 $ 2,657
vergreen Drive 2 5 45 60 20 50 02 60{) 219,000 I,', 1(' 4:;P $ 150,000 $ 20,000 $ 10,000 . 5,000 $ 10,000 $ 15,000 $ 30,000 $ 240,000 $ 48,000 . 57,600 . 345,600 $ 6,912
nlet Drive la.2a 3 65 28 35 400 4.8 115,000 41,975.000 ; ~;, i1:; :F';"; $ 700,000 $ 40,000 $ 20,000 $ 10.000 . 25,000 $ 25.000 . 75.000 . 895,000 $ 179,000 $ 214,800 $ 1,288,BOO . 3,222
..aurel Lake 12 3 1 25 25 450 8.1 220,000 80,300,000 ()ll\1 ''':Jt, )(1 $ 725,000 $ 40,000 $ 20,000 $ 10,000 $ 30,000 $ 25,000 $ 75,000 . 925.000 $ 185,000 $ 222,000 $ 1,332,000 $ 2,960
ain Bayview 3 3 45 45 55 25 3.3 5.000 1,825,000 l'l(i 7,:1(>; $ 150,000 . 15,000 $ 7,500 . 3,000 $ 10.000 $ 15,000 $ 30.000 . 230,500 $ 46,100 . 55,320 $ 331,920 $ 13,277
iddle Road, e" 1 3 1.5 25 15 50 4.6 13,700 5,000.500 C1:' 1(1(1( , $ 150,000 $ 20,000 $ 10,000 $ 5.000 . 10,000 $ 15,000 $ 30,000 . 240,000 $ 48,000 $ 57,600 $ 345,600 $ 6,912
ill lane 1,2 35 6 35 90 600 15 55.000 20,075,000 1,"-' -lliJ/J $ 960,000 $ 60,000 $ 25,000 $ 12,000 $ 35,000 $ 25,000 $ 75,000 $ 1.192.000 $ 238,400 $ 286,080 $ 1,716,480 $ 2,861
Id North Rd 1.2.3 3 7 65 40 800 19 90.420 33,003,300 1(;(' 1)<',;." $ 1,050,000 $ 75,000 $ 35,000 . 15,000 $ 50.000 $ 40,000 $ 100,000 $ 1,365,000 $ 273,000 . 327.600 . 1,965,600 $ 2.457
unset Drive 1 3 6 30 140 130 2.1 16.450 6,004,250 ll:W 13JV,(i $ 450,000 $ 30,000 $ 15,000 $ 7,000 . 15,000 $ 15.000 . 50.000 . 582,000 $ 116.400 $ 139.680 $ 838,080 $ 6,447
enny's Road 1 3 3 45 25 500 13.7 412,000 150,380,000 1\1() JUO 7Gr! $ 775,000 $ 45,000 $ 20,000 $ 15.000 $ 30,000 $ 25,000 $ 80,000 $ 990,000 $ 198,000 $ 237,600 $ 1,425,600 $ 2,851
Totals 3,345 1,262,420 460,783,300 68:; 93164? $ 6,310,000 $ 420,000 $ 197,500 $ 107.000 $ 235,000 $ 215,000 $ 590,000 $ 6,209,500 $ 1,443,900 $ 1,732,680 $ 11,388,080
"""'"
(a) Water Quality Data from SCWA lab
(b) Treatment System Cost Estimates provided from Basin Water
( c ) Treatment System has a estimated Ufe of 20 years
(;pnpmINnlp,,"
Total Present Worth of Treatment System Replacement Costs at years 20, 40, 60 & 80 =
(6.00% Interest & 20% Admin. & Cont.)
$
3,398,314
1 Average Yearly Well Production is based on SCWA Production Control Pumpage Data fOf years 1999. 2000 and 2001
2. Waste Brine storage (tankage) is included as part of system costs
Grand Total of Estimated Stte Treatment System and Treatment System Replacement Costs
$
14,784,394
.
Basin Water Norttllork Cost Sheel#4 090402 9/25102
.
.
.
DRAFT
TABLE 12. NORTH FORK PERCHLORATE REMOVAL TREATMENT SYSTEM - OPERATION & MAINTENANCE COST ESTIMATE SUMMARY TABLE
GENERAL WELL INFORMATION ANNUAL TREATMENT SYSTEM OPERATION & MAINTENANCE COST ESTIMATES
Variable O&M Costs Fixed O&M Costs
A . Site Well Water I a
Approx. Avg. Waste A"IJ. Variable OAM Fixed OAM Costs Total estimated
Treated Hours! Avg. Dally Avg. Yearly Brine Yearly Waste Brine Salt (SocIium Additional Water Quality MalnteRance - Mise. Parts & Sub Total Sit Adm/nls- Contingency Total estimated Costs per 1,000 OAM Annual
Pump Station Well.'s Perchloral Nitrogen Sulfate Chloride Well Field Waste Operator Electric Treatment Annual Site gallons Treated per 1,000 gallons
asN (504) (mgll) Flow day wells gallons/day Production (gal.) Flow Rate Brine Disposal Chloride) Labor Samples Mechanics Materials Costs tratlon(l00/o) (100/0) Treatment Costs (wl2O% Admin. & Treated (w/20% Costs per 1,000
e(ugll) (mgll) (mgll) (gpm) operated (gpm) Admin. & Cont.) gallons Treated
(gals) Cont.)
ckef1y Pood 12 4 8 65 100 840 66 334,250 122.001,250 1,"0 !..\b'1\'- S 19,753 $ 10.980 $ 10.065 $ 2.250 $ 5.200 S 2,800 $ 1,000 $ 52,048 $ 5,205 $ 5,725 S 62.976 S 0.30 S 0.21 S 0.52
vergreen Drive 2 5 45 60 20 50 02 600 219.000 CI<' .u,; $ 35 $ 20 S 10.065 S 300 S 5.200 S 2,800 $ 1,000 $ 19,420 S 1,942 S 2,136 S 23.496 S 0.30 $ 106.11 S 10730
nle1Drive 1a.2a 3 65 28 35 400 48 115,000 41975.000 ',(I b:,'}__.(; $ 6,716 S 3,778 S 10065 S 1.125 S 5.200 S 2,800 S 1,000 S 30,684 S 3,068 S 3,375 S 37.127 S 0.30 $ 0.56 S 088
aurelLake 12 3 1 25 25 450 81 220,000 80,300,000 c! 9iJ 1h!hO:1 $ 12.848 $ 7,227 S 10,065 S 1,350 S 5,200 S 2,800 S 1,000 S 40.490 S 4.049 S 4.454 S 46.993 S 0.30 S 0.31 S 061
ain Bayview 3 3 45 45 55 25 33 5,000 1.825.000 c, H~ <0.) $ 288 $ 184 S 10,065 S 300 S 5,200 S 2,800 S 1000 S 19,817 S 1.982 S 2.180 S 23.979 S 0.30 S 12.73 S 13,14
iddle Road. P""omc 1 3 15 25 15 50 46 13,700 5.000.500 '11r> ':}}C' $ 800 $ 450 S 10,065 S 300 5 5,200 S 2.800 S 1,000 S 20,615 $ 2,062 S 2,268 S 24.944 S 0_30 S 465 S 499
ill Lane 1,2 35 6 35 90 600 15 55,000 20,075,000 1 ~") .11023 S 3,346 $ 1,807 S 10,065 S 1,800 $ 5,200 S 2.800 $ 1,000 S 26,018 $ 2,602 S 2,862 S 31.481 S 0.31 S 1.25 S 1,57
Id North Ad 1.2,3 3 7 65 40 800 19 90,420 33,003,300 '(,I) bbuO S 5,281 $ 2,970 S 10.065 S 1.800 S 5.200 S 2,800 S 1,000 S 29,116 S 2,912 S 3,203 S 35.230 S 0.30 $ 0.76 S 1,07
unsetDrive 1 3 6 30 140 130 21 16,450 6.004,250 C).1O 1:<,.,0,(, $ 1,108 $ 540 S 10.065 S 750 S 5.200 S 2,800 S 1,000 S 21.464 S 2.146 S 2,361 S 25.971 S 0.33 $ 3.96 S 4.33
enny's Road 1 3 3 45 25 500 13.7 412,000 150.380,000 II}I) 30(J,cbO $ 24,061 S 13,534 S 10,065 $ 1,500 S 5,200 $ 2,800 S 1.000 S 58,160 $ 5,816 S 6,398 S 70,374 S 0.30 S 0.16 $ 047
Totals 3,345 1,262,420 460,783,300 (,Wi Ci."t>lC:' $ 74,235 $ 41,470 $ 100,650 $ 11,475 $ 46,800 $ 25.200 $ 9,000 $ 317,831 $ 25,967 $ 28,564 $ 372,362
""""
(a) Water Quality Data from SCWA Lab
(.;,p.m~ml Nnlp~
TOTAL VARIABLE O&M TREATMENT COST PER 1,000 GALLONS TREATED =
0.30
$
1 Average Yearly Well Production is based on SCWA Production Control Pumpage Data lor years 1999.2000 and 2001
TOTAL AVERAGE FIXED O&M TREATMENT COST PER 1,000 GALLONS TREATED =
$
0.50
"
Suffolk County Water Authority - Engineering Dept.
. DRAFT
Table 13. Capital and Operation and Maintenance Costs for a Reverse Osmosis Desalination Treatment System at a Typical SCWA
North Fork Well Field, Town of Southold, New York
A. CAPITAL COSTS - Based on a 1.0 MGD (694.4 gpm) Treatment System
Item Unit Quantity Unit Cost Total Cost
Structures
1) Treatment System Building Enclosure, Complete including all SF 2800 $100 $ 280,000
electric, heat, ventilation, insulation, doors, hardware, etc.
2) Concrete Foundation for Treatment System Building, Complete, L.S. $35,000 $ 35,000
including all reinf., slabs, etc.
Des~lin8tion System
3) 1.0 MGO (694.4 gpm) Reverse Osmosis Desalination Treatment Each 3 $840,000 $ 2,520,000
System {three (3) - 250 gpm R.O. Systems in Parallel} Complete
as manuf. By Crane Environmental Products, including PLC
Controls, SS High Pressure Piping and Valves, Epoxy coated SS
Frame, Duplex SS Centrifugal Pump, Energy Recovery Turbine, 5-
micron Prefillers, Auto Permeate Flush, Antiscatant Dosing Pump,
TDS Meter, Digital Flow meter, Pressure Switches, Seawater
8"x40' Membranes, Delivery, etc.
4) Installation of Reverse Osmosis Treatment System, Complete, L.S. $40,000 $ 40,000
including all rigging, assembly, piping, fittings, etc.
. 5) Brine Discharge Outfall Pipe and or Injection Well @ 300 gpm, L.S. $100,000 $ 100,000
Complete.
8) Misc. Interconnecting Piping between Systems and Yard Piping, L.S. $25,000 $ 25,000
Complete
Electrical
7) Upgraded Electric Service (2,000 amp), Underground Conduit & L.S. $300,000 $ 300,000
Control Aoom Electrical Work, Complete
Yard PiDlno
8) Yard Piping Complete, Including all misc. fittings, Copper, Gaskets,
Thrustblocking, Aoding, etc.
a. 6-inch diameter L.F. 200 $20 $ 4,000
b. 12-inch diameter L.F. 600 $40 $ 24,000
9) Valves and Hydrants L.S. $5,000 $ 5,000
10) Labor for Yard Piping Installation Day 10 $2,700 $ 27,000
llIllllr
11) Misc. Site Work - including Asphalt Paving to Treatment System, L.S. $75,000 $ 75,000
Grading, Topsoil and Seeding Landscaping, Fencing, etc.
Subtotal: $ 3,435,000
Engineering (20%): $ 687,000
Contingency (20%): $ 824,400
. TOTAL ESTIMATED CAPITAL COST: $ 4,946,400
_.
.
Suffolk County Water Authority - Engineering Dept.
DRAFT
Table 13. Capital and Operation and Maintenance Costs for a Reverse Osmosis Desalination Treatment System a1 a Typical SCWA
North Fork Well Field, Town of Southold, New York
B. O&M (ANNUAL) COSTS - Based on 1.0 MOO * 300 days per year = 300 Million gallons per year treated
Item
Unit
Quantity
Unit Cost
Total Cost
Operational
1)
Antiscalant Chemical
GaUon
3,000
$
10.00 $
30,000
2)
Wastewater Disposal - Permit Fees, Sampling, etc.
L.S.
$
3,000.00 $
3,000
3)
Operator Costs. includes daily system check, collecting samples.
etc. (avq. 4 hrsJday)
man-hours
1,200
$
55.00 $
66,000
4)
Electric - includes only the electricity for the R.O. treatment system
(1,500 hp . 300 days/yr @ 24 hr/day)
kwlhr
8,056,800 $
0.15 $
1,208,520
5)
Water Quality Samples - Daily Analysis of Raw and Treated Water
each
600
$
100.00 $
60,000
Maintenance
1) P.C. Mechanic Costs - General maintenance of System, Pumps, man-hours 250 $ 70.00 $ 17,500
Valves, pressure gauges, flow meters, controls and switches, etc.
.
2) Misc. Parts and Materials L.S. $ 10,000.00 $ 10,000
Subtotal:
Administration (10%)
ContinQencv (10%):
$ 1,395,020
$ 139,502
$ 153,452
$ 1,687,974
$ 5.63
TOTAL ESTlMATEO ANNUAL O&M COSTS,
TOTAL ESTIMATED O&M COSTS PER 1,000 GALLONS TREATED:
Operation & Maintenance Treatment Cost Assumptions
1) Yearly O&M Treatment are based on system operating @ 694.4 gpm for 24 hours/day and 300 days/year for a total of 300 million
gallons of treated water per year.
2) pH adjustment (Ume) and sodium hypochlorite costs are not included in this cost estimate
3) Electric costs are provided only for the operation of the R.O. Treatment process, Seawater Intake Pump electric costs are not included.
.
4)
Average Total Treated flow for the Desalination Treatment System =
300,000,000 gallons.