CROTON WATER FILTRATION PLANT ABOVE GROUND ...

CROTON
WATER
FILTRATION
PLANT
ABOVE
GROUND
BUILDINGS
& LANDSCAPE
1

CROTON
WATER
FILTRATION
PLANT
ABOVE
GROUND
BUILDINGS
& LANDSCAPE

CONtENtS
Introduction
NYC Water
Project Proforma
DEP Utility
DPR Recreation
Integration
Site Stormwater
Site Ecology
Site Security
Materials
Assembly
5

INtRODUCtION
America’s infrastructure is in disrepair. Our
utilities and services, roads, bridges, and
transportation networks need updating and
modernization. As architects and engineers,
we currently have a unique opportunity to
provide modernized infrastructure while also
providing our communities with civic spaces
that improve our quality of life.
The Croton Water Filtration Plant Project,
designed to filter and deliver 290 million
gallons of water per day - up to 30% of
New York City’s potable water supply, is
an integral part of the city’s infrastructure
and was required under a Consent Decree
entered into by the State of New York, New
York City and the Federal Government In
1998. In that decree, the city agreed to
site, construct and operate a facility to filter
water from the Croton Reservoir system.
6
In 1999, after extensive public hearings
and comment, the New York City Council
approved the Department of Environmental
Protection’s application to site a water
filtration plant at the Mosholu Golf Course in
the Bronx.
The design of the Above Ground Buildings
and Landscape (the filtration plant is
below grade) was procured by Grimshaw
in 2006 under the New York City Design
and Construction Excellence Initiative
(D+CE). Developed and led by Michael R.
Bloomberg since 2004, the D+CE is a great
example of how governmental programs
can propel visionary design leading to
inspirational, sustainable, and high quality
design that is publicy funded and managed
by government agencies. In large part,
the D+CE has enabled the success of the
Above Ground Buildings and Landscape at
the Croton Water Filtration Plant.
Through this project, the New York City
Department of Environmental Protection
(DEP), the Department of Parks and
Recreation (DPR) and the Department of
Design and Construction (DDC) are working
together to create a global landmark: a
complex, publicly funded civic infrastructure
project at the forefront of environmental
strategies on the largest scale that will
update our essential urban infrastructure
while simultaneously promoting community
and providing a public amenity.

The Croton Water
Filtration Plant is a
multifunctional design
strategy that provides
habitat, park restoration,
visual enhancement and,
above all, site security
for a multi-billion dollar
public works facility.
A birds-eye view of the site at
the Croton Water Filtration Plant.
The Department of Parks and
Recreation’s Golf Clubhouse is
shown in the foreground and the
Department of Environmental
Protection plant access buildings
are shown in the background.
The 9-acre green roof and driving
range are located in the center
of the site connecting the two
dissimilar programs together.
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NYC WAtER
In 1985, the Safe Drinking Water Act was
amended to require water suppliers relying on
surface water systems to filter their water or
meet stringent criteria relating to both water
quality and the ability to control activities
within its watershed. At the time, Croton’s
water quality was in jeopardy due to naturally
occurring compounds in the water as well
as the city’s ability to permanently protect
the Croton water supply from degradation.
As a result of both watershed quality and
watershed control, New York City elected to
build the Croton Water Filtration Plant.
8
The Croton Watershed currently has a
resident population of 193,000 persons. It
provides approximately 10 percent of the
city’s average daily demand during periods
of normal rainfall and up to 30 precent of the
city’s average daily demand during drought
conditions.
New York as also added two more protected
watersheds, the Catskill and Delaware
watersheds, in order to keep up with the
drinking water demands of New York City’s
population of 8 million.
The spillway at the New Croton Dam
in Cortland, NY, 1907.
From here, the New Croton
Aqueduct delivers water from
upstate New York to the Croton
Water Filtration Plant in the
Bronx.

New York City’s
current daily drinking
water demand is
1,293 million gallons
per day.
Map of New York City’s Watersheds.
The Croton Watershed provides
approximately 10% of the City’s
average daily demand during periods
of normal rainfall, and up to 30%
of the City’s average daily demand
when rainfall is below normal.
9

PROJECt PROFORMA
The 24-acre site at Mosholu Golf Course
was chosen for plant construction in late
1998. A federal government mandate
demands that any facility displaced by the
construction of the plant must be restored
following the completion of the project.
Therefore, the course’s driving range and
tee boxes, club house and parking lot had
to be redesigned and reconstructed after
the plant was operational. As a result, the
program required the seamless integration
of a publicly accessible golf course driving
range and clubhouse with the above grade
facilities that service the plant. All of this
is in concert with the local landscape and
ecology of one of New York City’s largest
and well known public park lands – Van
Cortlandt Park.
12
With the introduction of the 9-acre water
filtration plant at the site, the Mosholu Golf
Course will have a decrease in permeable
surface area, severely reducing the ability
of the site to absorb rainfall. Inspired
by the treatment of drinking water – the
very reason the plant is required – the
design team looked to natural water
treatment strategies to manage the water,
demonstrating the need to provide sensitive
building development that improves the
natural environment rather than damage
it. As the Croton Watershed is developed
and population increases, best practices for
stormwater management must be a high
priority if we are to prevent contamination of
the city’s waterways through the combined
sewer system.
Plan of the Above Ground Buildings
and Landscape at the Croton Water
Filtration Plant.
New York City has often suffered unsafe
water conditions when excess stormwater
overloads its sewage treatment plants,
discharging raw sewage into local
waterways. By demonstrating best practices
for stormwater management on an urban
scale, the design team has developed
a sophisticated water balance system
that retains stormwater on site, prevents
discharge into the city’s combined sewers
and stores it for irrigation for the driving
range and golf course. The system also
acts as a natural security barrier, preventing
access along the perimeter of the plant
and insuring the security of the facility. It
is an essential component that performs a
dual purpose, successfully integrating the
challenging DEP and DPR programs.

Exploded axonometric of the Above
Ground Buildings.
The driving range as depicted
in the illustration to the left
is located on top of the Water
Filtration Plant. A 9-acre high
performance green roof on
top of the plant is required for
replacement of the driving range.
This will be the largest contiguous
green roof in North America.
The water
filtration plant
is organized on
four levels and
descends 100
feet into the
ground.
13

DEP UtILItY
The northern half of the site is designated
for DEP use only. Here the DEP will access
all plant related activities.
Upon entering the site at the DEP
secure entrance, all staff and visitors are
announced and scanned to assure a
controlled environment once inside the
plant. The secure entrance has been
designed with the most advanced security
equipment available today. Ballistics,
blasting and contamination have all been
considered when protecting the plant. The
secure entrance is complete with a security
booth and lightweight fabric canopy to
protect entrants from inclement weather.
All chemical filling occurs at the Chemical
Fill station. Deliveries of chemicals for
treatment will be discharged into the filling
station several times per day. This area
is also covered with a second lightweight
canopy for weather protection.
The DEP Secure area is 4-acres in
size and includes the Arrivals and
Receiving Building, Chemical Fill
Station, Police Booth and Secure
Entrance Area.
14
DEP staff will enter the filtration plant
through the Arrivals and Receiving
Building. The building is constructed
primarily of architectural concrete. The
refined, industrial look compliments the
complexity of the plant’s pumps and
treatment tanks below. The exterior of the
building is clad with stone and weathering
steel panels. These very durable materials
are used for both architectural expression
and to withstand the intensive external use
of the facility. Finally, the building exterior
includes nine 125 feet high golf netting
poles. The netting system is designed to
protect DEP operations personnel from
errant golf balls from the adjacent golf
driving range.
Designed by Hazen & Sawyer/Metcalf &
Eddy Joint Venture, the water filtration
plant is located almost entirely below
grade. The building is organized on four
levels and descends 100 feet into the
ground. Key operational components are
located above grade to facilitate ingress/
egress, chemical filling and security.

Green Roof
Clerestory
Blue Stone Cladding
Precast Concrete
Panel Cladding
Catwalk
Support Structure
Perforated Weathering
Steel Wall Panels
Exploded Axonometric of the Arrivals
and Receiving Building. The steel
wall will extend 200 feet into the
landscape and is comprised of 376
individual panels.
Department of Environmental
Protection entrance at the Arrivals
and Receiving Building.
15

DPR RECREAtION
The eastern side of the project site along
Jerome Avenue is dedicated to the
Department of Parks and Recreation (DPR)
use and is where the public will access
the Mosholu Golf Course for golfing related
activities.
Visitors will enter the golf course along
Jerome Avenue at 213th street. The
second entrance to the site includes a 75
space parking lot for golf related activities.
Visitors will park and move south into the
golf course entry plaza. The centrally
located plaza shown above is adjacent to
the first tee, club house café and viewing
platform where visitors can view the water
balance cell system, natural landscape and
the adjacent driving range. Other amenities
located at the plaza include interpretive
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exhibits to educate the public on water
savings and sustainability. After checking
into the clubhouse a visitor can make their
way to the tee box area to practice their golf
swing or proceed to the first tee to play the
nine hole golf course.
The clubhouse building is long and
slender, sloping up and out of the park’s
natural landscape. The building’s green
roof connects with the park’s surface and
local ecology, ultimately concealing the
building when viewed from the surrounding
neighborhood. The building houses a
restaurant, pro shop, and golf course
administrative facilities. It also includes
a multipurpose space for meetings,
presentations and special events. The
building’s green roof will be accessible
Entry Plaza at the Moshulu Golf
Course Clubhouse. The green roof
atop the clubhouse is an intensive
green roof system comprised of
drought tolerant sedum plants.
to increase activity on and around the
building. Most importantly, roof access
gives a unique vantage point in which to
view and interpret the sinuous shape of
the site and the above grade water balance
system.
The driving range is surrounded by a
constructed wetland system. This provides
natural protection for the plant and
prevents golfers from accessing the plant’s
green roof. The 14-acre driving range is a
combination of on-podium and
on-grade landscaped surface. The
range has been designed to most closely
resemble a golfer’s fairway experience. It
includes surface treatment such as varying
turf type and grass lengths, synthetic turfs
and sand trap hazards to provide the most
challenging experience possible.

Rendering of the Moshulu Golf Course
Entrance Area. 34 golf netting
poles ranging in height from 30
feet to 125 feet, surround the golf
range, protecting golfers and DEP
personnel from errant golf balls.
The golf clubhouse, covered
by a green roof, gently slopes
out of the ground, blurring
the line between building and
landscape.
17

INtEGRAtION
Site Stormwater
Site Ecology
Site Security
20
Grimshaw was not involved during the
early stages of the design and engineering
of the water treatment plant. At that
time, the Above Ground Buildings and
Landscape were being designed by the
plant engineers. In order to acquire design
approval from the New York City Design
Commission, Grimshaw was contracted
to develop an integrated approach to
the buildings and surrounding natural
landscape.
The project’s fundamental premise,
water, a vital resource to the health
of our population, has been used as
the generating principle for security,
landscape, and above grade building and
landscape design. Storm and ground
water is collected and redistributed through
a system of landscape interventions and
site subtractions.
Through the use of bioswales and runnels,
the water is directed into collection ponds
and filtering locations. This surface water
flows naturally without the use of pumps,
pipes or valves. These ‘moats’ also serve as
security boundaries necessary to protect

the plant and eliminate the need for
unsightly fencing. It is a multifunctional
design strategy that provides park
restoration, habitat, visual enhancement
and most of all security for a multi-billion
dollar public works facility.
New Croton Dam. 1907.
Historic Croton Infrastructure
integrated and complementing the
topography of upstate New York.
Surface water in the
watershed is captured in a
series of twelve reservoirs
and three lakes on the Croton
River and its tributaries. The
water is sent to the city via
the New Croton Aqueduct.
21

Site
Stormwater
22
Both ground and stormwater make
up vast quantities of water that would
otherwise be discharged into the city’s
combined sewer system. Our challenge
is to collect, clean and store this water on
site, eventually reusing it for irrigation and
other non-potable water uses rather than
resorting to potable water.
Beginning below grade, ground water
seeps through the bedrock and is
deposited at the base of the water filtration
plant. From here it is collected and moved
by dewatering pumps up to retention
Supply
basins near the surface. An estimated
55 gallons per minute will be collected
here. Rain water will also be collected and
retained in these underground basins. A
9-acre green roof located on top of the
filtration plant will see the largest volumes
of water.
Finally, a system of bioswales and runnels
collect the remainder of the site stormwater
runoff from roadways and parking lots.
The swales move water across a planted
system designed to absorb water and
process parking lot contaminants that

sometimes include heavy metals or
petroleum products. At the end of the
swales, remaining water drains into the
storage basins to join collected ground and
other site stormwater.
Following its collection from the base of
the plant and surface areas, the storm and
ground water is pumped to a high point on
the site and discharged into an on-grade
constructed wetland system. Consisting
of 10 individual treatment cells, the water,
led by gravity, flows naturally downhill
without the use of pumps, pipes or valves.
Stormwater collection
at Croton will reduce the
use of potable water for
irrigation by up to 40%.
Demand
23

Green Roof
The plant’s roof, a 9-acre impermeable
surface, will cause rainwater to flow off the
site where soil infiltration once occurred.
To prevent this impact, the project’s design
claims the roof as an opportunity:
providing a rolling, secure green surface
for Van Cortlandt Park’s new driving range,
and a system to collect and reuse stormwater
for irrigation and habitat creation.
As a public amenity, the country’s largest
contiguous green roof will serve as a
driving range target for golfers visiting the
park. Tee boxes along the east perimeter
of the green roof will overlook its undulating
surface. Approximately 23,000 cubic
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E
C
C
D
B
yards of lightweight engineered soil
combined with geofoam will minimize
the structural burden on the plant below.
The topography also masks the plant’s
air handling machinery, integrating the
circular structures with the topography of
the roof’s planted surface.
The project’s stormwater collection system
is also integrated into the green roof
assembly. Rather than quickly shedding
water, the vegetation and soils of the roof
will slow precipitation, absorbing substantial
volumes of water, preventing runoff.
In saturated conditions during significant
storm events, percolated water is wicked
B
A
Green Roof turf planting diagram.
from the green roof strata through an
underlying drainage network of stone filled
baskets. This collected water is directed to
underground basins where it is combined
with pumped groundwater, and then
sent through the project’s cell system to
support the growth of wetland ecosystems
and ultimately the golf course’s irrigation
demand.

A
B
C
D
E
PLANTING KEY PLAN
A. Turf Type 1 (1-1.5” height)
B. Turf Type 2 (2” height)
C. Turf Type 3 (mow seasonally)
D. Synthetic Turf
E. Limestone Screenings
Water Filtration Plant. The roof has
been completed and waterproofing
is underway.
When completed, the driving
range at the Croton Water
Filtration Plant will be the
nation’s largest contiguous
high performance green roof,
measuring 400,000 square feet,
or 9 acres, in total area.
25

Site Ecology
The location of the project in Van Cortlandt
Park demands that the above ground
surfaces of the facility be cloaked in
vegetation, integrating the plant with the
surrounding parkland, golf course, and
ecosystems. The breadth and scale of the
project’s components – the expansive,
at-grade plant roof, stringent site security
measures, and excessive amounts of
stormwater and pumped groundwater
– establish a variety of complex ground
conditions, requiring a nuanced approach
to planting design.
The design response, a varied suite of
native plant communities, is attuned to
the project’s differing ground conditions -
from dry, sunny green rooftops composed
of sedums, to the consistently inundated
26
Golf Course
Wetland
Cell System
plant communities of the wetland cell
system. Not only will these communities
lend their textures and colors to help
define the project’s appearance, but they
also will provide ecological services such
as nutrient uptake, carbon dioxide fixation,
habitat value, and water absorption.
The project’s wetland cell system provides
the most significant ecological feature of
the project. The initial flat, sunny cells
host shallow emergent marshes and
shrub swamp vegetative communities, full
of sedges, rushes, and wetland shrubs
such as blueberry and dogwood. Here,
the nearly flat grade, dense plantings,
and thick soils slow the collected water,
allowing suspended sediment to settle and
nutrients to be absorbed. The following
Driving Range
WTP
Site Section
A section drawing cut on
the southwest corner of the
project site depicts the various
programmatic elements at work.
cells - shaded, narrow, and more steeply
pitched - enliven the collected water,
quickening and spilling it over rough
cobbles to both lower water temperature
and increase dissolved oxygen. Associated
plantings here recall rocky glens of the
nearby Bronx River with various fern and
shade-loving species.
Lastly, a deep emergent wetland cell
provides a basin within which native lotus
and lily pads float and bloom. In this cell,
the large volume of water allows for a more
complex ecosystem with wetland margins
and open water areas, yet also serves as
the reservoir from which the adjacent golf
course and driving range’s irrigation water
will be drawn.

Stormwater collection at
the Croton Water Filtration
Plant will offset the
discharge of stormwater
into the city’s combined
sewer by up to 40%.
Wall Mounted Motion Sensors
Emergent Marsh Wetland Plantings
Cell
Wetland Cells 4 and 5
Axonometric view of cells 4
and 5, part of the wetland cell
system that filters stormwater and
groundwater collected on site.
Surveillance Access
CCTV
Weir Structure
Cell
Security
Blue Stone Gabion
Basket Wall
Rocky Glen Wetland Plantings
Blue Stone Clad Cast in Place Concrete Wall
27

Materials
Natural material selection was paramount
to developing a scheme that integrated
physically and aesthetically into the
surrounding park landscape.
Both the DEP and DPR buildings have
been developed in concert so that all
32
buildings would have an overall unified
appearance.
Blue Stone quarried in Alcove, New York,
contains natural color ranges including
burnt umbers and sienna, contrasted with
warm blue tones. Natural oxides in the
1 2 3
stone are revealed on the surface and
coordinate with the weathered steel wall
throughout the landscape.
Green roof plantings top all buildings on
site and complement the timber columns
used at the club house.
4

Clubhouse Entrance. Looking
toward the clubhouse from Jerome
Avenue reveals the green roof that
tops the structure.
5 6
7
Spillway, Downsville Dam, Pepacton
Reservoir, Delaware County, New
York. 1907
1. Gabion Wall
2. 8” Quarry Stone
3. 4” Quarry Stone
4. 2” Quarry Stone
5. Corten Steel
6. Cast-in-place Concrete
7. Glulam Wood
33

Assembly
Plant construction began in 2006 with
excavation of the 9-acre plant site. its
completition is approaching rapidly with
testing of the plant’s filtration systems
scheduled for late 2012. The DEP related
above ground buildings will be complete
in 2014 which will include the DEP
Secure Entry, the Chemical Fill Building
and the Arrivals Receiving Building.
Commencement of the DPR related above
ground buildings will begin in 2014 and be
completed in 2016. All told this will be a
project that has spanned close to 15 years
in the making.
The building construction at Croton
includes several unique material uses and
techniques for assembly. Weathering
34
steel has been used as protection for the
Arrivals Receiving Building. The wall itself
is made up of 376 panels extending 200
feet into the landscape. The material is
perforated for translucency and is tapered
as it moves away from the structures,
blending into the landscape. Over 16,000
sqft of material will be used to protect and
integrate the buildings into the landscape.
The Arrivals Receiving Building is
constructed using architectural concrete.
The material is used to achieve greater
workability within very dense rebar
required for high pressure design
requirements. The material is also
used to achieve a higher quality finish,
allowing for greater detail within the
surface of the material. Color enhancers,
steel embedments and all mechanical,
electrical, and plumbing components
have been integrated into the formwork
to achieve the highest quality of the
unobstructed surface.
Stone clad landscape retaining walls
encircle the entire site. 3600 linear feet
of wall is planned for the site with 9000
cubic yards of stone. The stone cladding
will be laid to follow the slope of the top
cap appearing to grow out of the park
landscape.
Finally, 250,000 cubic yards of concrete
will be used to construct the filtration plant
and above ground buildings.

Aerial View, Water Treatment Plant,
2011.
Construction of
the plant will
require more
than 250,000
cubic yards of
concrete.
Weathered Steel Panel
Quarry Stone Wall
35

Assembly
36
View looking north from the driving
range through the Arrivals and
Receiving Building entrance lobby.
The entrance lobby will overlook
the Moshulu Golf Course driving
range.

View of the underside Arrivals
and Receiving Building Roof. The
building is fitted with glazing at
high level to allow light into the
entrance areas of the plant.
View looking west towards the Arrivals and Receiving Building (Left) and Chemical Fill Station (Right)
37

Team
GRIMSHAW
KEN SMITH LANDSCAPE
ARCHITECT
ATELIER TEN
GREAT ECOLOGY AND
ENVIRONMENTS
RANA CREEK
SHERWOOD DESIGN ENGINEERS
DEWHURST MACFARLANE
AND PARTNERS
BURO HAPPOLD
AMMAN & WHITNEY
ARUP LIGHTING
39

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GRIMSHAW
New York
637 W 27 St
New York
NY 10001
T +1 646 293 3600
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57 Clerkenwell Road
London
EC1M 5NG
T +44 20 7291 4141
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Melbourne
VIC 3053
T +61 3 9321 2600
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Sydney
NSW 2000
T +61 2 9253 0200
info@grimshaw-architects.com
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