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Croton Water Filtration Plant

Decision to Build

June 2004

Construction Began

2007

Low Bidder Pulled Out

April 2007

Skanska Contract Awarded

August 2007

Start-Up Phase

Six months

Project Completed

2015

Capacity

320mgd (1.2 million cubic metres a day)

Population Served

One million

Building Footprint

377,000ft² (34,270m²)

Site

12 acres (4.8 hectares)

Main Treatment

DAF / Filtration

Disinfection

UV and Chlorination

Flocculation

2-stage; 144sec/stage minimum

DAF Loading Rate

50gpm

Filter Type

Dual media – 60cm anthracite, 30cm sand

DAF Sludge Treatment

Skimmed solids dewatered by centrifuge

Project Sponsor

New York City Department of Environmental Protection

Main Contractor

Skanska

Additional Contractor

Tully Construction

Geo-Technical Consultants

Haley & Aldrich

Digital Automation Architecture

Emerson

Client Consultant

Hazen & Sawyer / Metcalf & Eddy JV

Turbidity NTU

1.1

TOC (mg/l)

2.8

TDS (mg/l)

186

Specific Conductance (umho/cm)

315

Phosphate (mg/l)

2.1

pH (pH units)

7.2

Nitrite

0.002

Nitrate

0.21

Hardness mg/l CaCO<sub>3</sub>

92

Alkalinity mg/l CaCO<sub>3</sub>

54.3

Colour (colour units)

12 (distribution system average) 5 – 40 (range)

Giardia Cycts

&#62; 99.9&#37; removal and inactivation

Cryptosporidium

99.9&#37; removal and inactivation

Viruses

&#62; 99.9&#37; removal and inactivation

Filtered Water Turbidity

&#60; 0.1 NTU

TOC

&#60; 2mg/l

True Colour

&#60; 5

Construction Contract Value

&#36;1.3bn
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