NYC Filtration Plant for Delaware and Catskill Systems

NYC Filtration Plant for Delaware and Catskill Systems

Filtration avoidance criteria Alternatives to Filtration? Where should the plant(s) be located?

Multiple plants or one plant? Treatment steps at different locations?

Design flow Treatment scheme Backwash water

Filtration avoidance criteria Alternatives to Filtration? Where should the plant(s) be located?

Multiple plants or one plant? Treatment steps at different locations?

Design flow Treatment scheme Backwash water

SDWA Turbidity LoopholeSDWA Turbidity Loophole

At no time can turbidity go above 5 nephelolometric turbidity units (NTU)

Systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95% of the daily samples for any two consecutive months

Delaware-Catskill turbidity range was ________ with an average of 1.06 NTU in 2000

NYC claims the MCL of 5 NTU is for a monthly average

At no time can turbidity go above 5 nephelolometric turbidity units (NTU)

Systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95% of the daily samples for any two consecutive months

Delaware-Catskill turbidity range was ________ with an average of 1.06 NTU in 2000

NYC claims the MCL of 5 NTU is for a monthly average

0.5-10.0

§ 141.71 Criteria for avoiding filtration.

§ 141.71 Criteria for avoiding filtration.

The turbidity level cannot exceed 5 NTU (measured as specified in § 141.74 (a)(4) and (b)(2)) in representative samples of the source water immediately prior to the first or only point of disinfectant application unless: (i) the State determines that any such event was caused by circumstances that were unusual and unpredictable; and (ii) as a result of any such event, there have not been more than two events in the past 12 months the system served water to the public, or more than five events in the past 120 months the system served water to the public, in which the turbidity level exceeded 5 NTU. An ‘‘event’’ is a series of consecutive days during which at least one turbidity measurement each day exceeds 5 NTU.

The turbidity level cannot exceed 5 NTU (measured as specified in § 141.74 (a)(4) and (b)(2)) in representative samples of the source water immediately prior to the first or only point of disinfectant application unless: (i) the State determines that any such event was caused by circumstances that were unusual and unpredictable; and (ii) as a result of any such event, there have not been more than two events in the past 12 months the system served water to the public, or more than five events in the past 120 months the system served water to the public, in which the turbidity level exceeded 5 NTU. An ‘‘event’’ is a series of consecutive days during which at least one turbidity measurement each day exceeds 5 NTU.

Limited Alternative To FiltrationLimited Alternative To Filtration

States may allow unfiltered water systems with surface water sources to use treatment other than filtration

In order to qualify for alternative treatment, a water system must have an __________, ____________ watershed in consolidated ownership and have control over access to and activities in the watershed

The alternative treatment must ensure _________ removal or inactivation efficiencies of pathogenic organisms than would be achieved by the combination of filtration and chlorine disinfection required by section 1412 (b)(7)(C). [1412(b)(7)(C)] Sec. 106

States may allow unfiltered water systems with surface water sources to use treatment other than filtration

In order to qualify for alternative treatment, a water system must have an __________, ____________ watershed in consolidated ownership and have control over access to and activities in the watershed

The alternative treatment must ensure _________ removal or inactivation efficiencies of pathogenic organisms than would be achieved by the combination of filtration and chlorine disinfection required by section 1412 (b)(7)(C). [1412(b)(7)(C)] Sec. 106

uninhabited undeveloped

greater

§ 141.71 Criteria for avoiding filtration

§ 141.71 Criteria for avoiding filtration

The public water system must demonstrate through ownership and/or written agreements with landowners within the watershed that it can control all human activities which may have an adverse impact on the micro-biological quality of the source water. The public water system must submit an annual report to the State that identifies any special concerns about the watershed and how they are being handled; describes activities in the watershed that affect water quality; and projects what adverse activities are expected to occur in the future and describes how the public water system expects to address them.

The public water system must demonstrate through ownership and/or written agreements with landowners within the watershed that it can control all human activities which may have an adverse impact on the micro-biological quality of the source water. The public water system must submit an annual report to the State that identifies any special concerns about the watershed and how they are being handled; describes activities in the watershed that affect water quality; and projects what adverse activities are expected to occur in the future and describes how the public water system expects to address them.

Where Should Plant(s) Be Located?

Where Should Plant(s) Be Located?

______________________________________________________________________

___________________________________ ___________________________________ ___________________________________

______________________________________________________________________

___________________________________ ___________________________________ ___________________________________

Between last watershed reservoir (Kensico) anddistribution reservoir (Hillview)

Near tunnel

On hydraulic grade line! (No pumps)

Commercial/Industrial area (not residential)

Design Flow for New Filtration Plant

Design Flow for New Filtration Plant

Max day ever was 94 m3/s in 1975 Future growth? Conservation?

Croton system is separate Proposed filtration plant for 12.7 m3/s Ability to shut down Croton system?

Catskill/Delaware plant Expert Panel 48.3 m3/s NYCDEP (Debra Thomas 10/27/97) 83 m3/s

Max day ever was 94 m3/s in 1975 Future growth? Conservation?

Croton system is separate Proposed filtration plant for 12.7 m3/s Ability to shut down Croton system?

Catskill/Delaware plant Expert Panel 48.3 m3/s NYCDEP (Debra Thomas 10/27/97) 83 m3/s

Croton PlantCroton Plant

The construction costs of the water filtration plant, with a design capacity of 290 million gallons per day (mgd), and the related facilities, is estimated at $660 million.

Annual operations and maintenance costs are projected to be $11 million.

The plant will use state-of-the-art disinfection and filtration processes including dissolved air flotation for the removal of solids, ozonation for primary disinfection, and biologically active carbon filtration.

The construction costs of the water filtration plant, with a design capacity of 290 million gallons per day (mgd), and the related facilities, is estimated at $660 million.

Annual operations and maintenance costs are projected to be $11 million.

The plant will use state-of-the-art disinfection and filtration processes including dissolved air flotation for the removal of solids, ozonation for primary disinfection, and biologically active carbon filtration.

3 3

33

$660,000,000 $5212.7

$5283 4.3 !

millionm s m s

millionm s billion

m s

=

× =

Maximum Daily FlowMaximum Daily Flow

0.00.010.010.020.020.030.030.040.040.050.050.060.060.070.070.080.080.090.090.0

1978

1978

1980

1980

1982

1982

1984

1984

1986

1986

1988

1988

1990

1990

1992

1992

1994

1994

yearyear

Max

imum

dai

ly d

eman

d (m

3 /s)

Max

imum

dai

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d (m

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Catskill/DelawareCatskill/Delaware

CrotonCroton

Treatment Plant Options for NYC

Treatment Plant Options for NYC

NYC’s water is high quality (<2 NTU) Low particle concentration means that

___________ ______ aren’t necessary Three options for WTP with high quality

surface waters Direct Filtration (most likely option for NYC) Contact Filtration Ultraviolet disinfection

NYC’s water is high quality (<2 NTU) Low particle concentration means that

___________ ______ aren’t necessary Three options for WTP with high quality

surface waters Direct Filtration (most likely option for NYC) Contact Filtration Ultraviolet disinfection

sedimentation basins

Direct FiltrationDirect Filtration

ScreeningScreening

Rapid MixRapid Mix

FlocculationFlocculation

FiltrationFiltration

DisinfectionDisinfection

StorageStorage

DistributionDistribution

Raw waterRaw water

AlumPolymers

AlumPolymers Cl2Cl2

sludgesludge sludgesludge

Contact FiltrationContact Filtration

ScreeningScreening

Rapid MixRapid Mix

FiltrationFiltration

DisinfectionDisinfection

StorageStorage

DistributionDistribution

Raw waterRaw water

AlumPolymers

AlumPolymers Cl2Cl2

sludgesludge sludgesludge

Size of Major Unit ProcessesSize of Major Unit Processes

Unit Process Parameter Range

Flocculation 10-30 min

Sedimentation Q/As 0.67 m/hr

Filtration Va 2.5 - 37 m/hr

Los Angeles - _______

NYC considering 15 - 30 m/hr (likely 25 m/hr)

Unit Process Parameter Range

Flocculation 10-30 min

Sedimentation Q/As 0.67 m/hr

Filtration Va 2.5 - 37 m/hr

Los Angeles - _______

NYC considering 15 - 30 m/hr (likely 25 m/hr)

37 m/hr

Backwash RequirementsBackwash Requirements

U FB B

TTotal filter bed areaotal filter bed area

Useable production (or area)

Production used for backwash

Filter beds off line to be backwashed

AT = AU + AFB + AB

Area of Filter Beds in Useable Production (U)

Area of Filter Beds in Useable Production (U)

Plant Design Flow 83 m3/s

Area required without backwash (Va = 25 m/hr)

Backwash requirements? 10 minutes at 50 m/hr once every 12 hours assume 30 minute downtime for backwash The useable filter bed area must be increased by 5 – 10%

to meet backwash requirements

Plant Design Flow 83 m3/s

Area required without backwash (Va = 25 m/hr)

Backwash requirements? 10 minutes at 50 m/hr once every 12 hours assume 30 minute downtime for backwash The useable filter bed area must be increased by 5 – 10%

to meet backwash requirements

23

U m 11,952

s 3600hr

hrm 25

/sm 83

VQ

A 23

U m 11,952

s 3600hr

hrm 25

/sm 83

VQ

A 36.4 ha siteha=10,000 m2

Backwash Water Disposal Options

Backwash Water Disposal Options

Backwash water production Approximately 3% of useable production! Not recycled because of potential concentration

of pathogens Solids production

particles present in raw water (0.1-10 mg/L) coagulant (5 - 50 mg/L)

Disposal options

Backwash water production Approximately 3% of useable production! Not recycled because of potential concentration

of pathogens Solids production

particles present in raw water (0.1-10 mg/L) coagulant (5 - 50 mg/L)

Disposal options

Area of Flocculation TanksArea of Flocculation Tanks

Hydraulic retention time of 10-30 minutes Los Angeles uses 8 minutes

Typical depth of 5 meters Area required for flocculation will be

similar to that required for filtration Contact filtration would eliminate the need

for flocculation tanks

Hydraulic retention time of 10-30 minutes Los Angeles uses 8 minutes

Typical depth of 5 meters Area required for flocculation will be

similar to that required for filtration Contact filtration would eliminate the need

for flocculation tanks

SummarySummary

NYC Catskill/Delaware WTP (if built) will be either direct or contact filtration

The WTP will be constructed somewhere between Kensico and Hillview Reservoirs

The WTP will be designed to handle recent peak daily flows: future demand will need to be restricted to current levels

The WTP will cost several billion dollars In the meantime, NYC will build an ultraviolet

disinfection plant.

NYC Catskill/Delaware WTP (if built) will be either direct or contact filtration

The WTP will be constructed somewhere between Kensico and Hillview Reservoirs

The WTP will be designed to handle recent peak daily flows: future demand will need to be restricted to current levels

The WTP will cost several billion dollars In the meantime, NYC will build an ultraviolet

disinfection plant.

Supply Aqueducts and Tunnels

Catskill Aqueduct

Delaware Aqueduct

East Delaware tunnel

West Delaware tunnel

Shandaken Tunnel

Neversink Tunnel

Kensico to Hillview

Kensico to Hillview

CatskillAqueductCatskillAqueduct

DelawareAqueductDelawareAqueduct

Possible Filtration Plant SitePossible Filtration Plant Site

Kensico

1 km

90 acre site36.4 haha=10,000 m2

Close to Catskill and Delaware Aqueducts

Possible Filtration Plant SitePossible Filtration Plant Site