DUKE UNIVERSITY
OPERATIONS AND MAINTENANCE TRAINING
CHWP-2 RECLAIM WATER
DU-107
1.0 PURPOSE
The purpose of the Operations and Maintenance Training Program is to train
Operations and Maintenance Technicians in the operation of the Duke University Chiller
and Steam Systems
1.1
OBJECTIVES
Trainees will demonstrate knowledge of:

Chilled Water Plant #2 (CHWP-2) Reclaim Water System Components

CHWP-2 Reclaim Water System Components Operation

CHWP-2 Reclaim Water System Configuration

CHWP-2 Reclaim Water System Controls and Instrumentation
2.0
CHWP-2 RECLAIM WATER PRINCIPLES
2.1 PURPOSE
The purpose of CHWP-2 Reclaim Water is to:
Reduce dependence on City of Durham water
Reduce costs
Reduce impact on the environment
Prevent loss of services during drought conditions
2.2 CHWP-2 RECLAIM WATER SYSTEM
Reclaimed water supplied the CHWP-2 cooling tower basin. Reclaim water comes from:
Air Handler Unit (AHU) cooling coil condensate
Wells
Creek
Storm drainage system and reclaim pond
Rainwater
The Control Room controls distribution of reclaim water to the cooling tower basin and
irrigation system.
2.3 WHY RECLAIM WATER?

In 2007 drought conditions in Durham NC reached record low levels in water
supplies. Duke helped lead the response.

Duke University growth from 2006 – 2010 of 7.4%.

Central Chiller System load increase from 2005-2010 of 60%.

Duke University is the largest user of water in the City of Durham.

At 30% of all water used, the Chilled Water System is the largest single
consumer of water at Duke University.
CHWP-2 can use 100 million gallons of water per day.
2.4 HOW DUKE HAS RESPONDED

October 2007, Duke University convened Water Conservation & Working
Groups, which analyzed all potable water use on campus.

In 2009 CHWP-2 underwent major renovation, resulting in Leadership in Energy
& Environment Design (LEED) Gold certification.
The reclaim water project supports the Governor Deval L. Patrick of North Carolina’s
“Leading by Example” initiative (Executive Order 484).
As of 2010, 43 million gallons of water per year have been saved.
When the Reclamation Pond is completed, an additional 100 million gallons of water per
year will be saved.
3.0 RECLAIM WATER PRINCIPLES

Reclaimed water is used for makeup feedwater and irrigation.

The CHWP-2 Reclaim Water System
o Reduces reliance on City of Durham water
o Saves money
o Reduces waste and impact on the environment

Water from the following sources is distributed through the CHWP-2 Reclaim
Water System:
o AHU cooling coil condensate
o Two wells
o Creek
o Storm Drainage System with Reclamation Pond (being constructed instream during 2014)
o Rainwater collected from the CHWP-2 rooftop
4.0 CONDENSATE RETURN PRINCIPLES

Condensate is the byproduct of heat transfer in the Steam Heating System.

Condensation forms in distribution piping and heating equipment.

As condensation forms in the underground piping, it is separated from the steam
in drip leg stations and returned to the plant where it will be used to preheat feed
water.

At a campus building, after steam has condensed and given up its valuable heat
in the air handler’s heat exchanger, the hot condensate is pumped back to the
boiler before it can cool.

The hot condensate is used to preheat feed water before it enters the boiler,
which helps the boiler run efficiently.
5.0
RECLAIM WATER SYSTEM
5.1 PURPOSE

Systems that make up the CHWP-2 Reclaim Water System efficiently and
responsibly supply water for:

The CHWP-2 cooling towers basin to help cool the basin and provide makeup
feedwater

Irrigation on campus
5.2 SYSTEM COMPONENTS
The Duke University CHWP-2 Reclaim Water System includes the following equipment
and locations:

Reclaim Water Supply

Reclaim Water Tanks

Reclaim Water Pumps

CHWP-2 Cooling Tower Basin

Irrigation System
5.3 RECLAIM WATER SUPPLY
Creek and Wells
Reclaiming creek water saves 22 million gallons per year.
Two wells save 1.5 million gallons per year.
AHU Cooling Coil Condensate
Reclaiming condensate from air handler cooling coils saves 15 million gallons per year.
Storm Water
Storm water runoff is collected in the storm drainage system.
The storm drainage system consists of nearly 32 miles of storm pipes and drainage
ditches.
Reclamation Pond
The storm water reclaim pond is being constructed in-stream of the storm drainage
system.
The pond will save approximately 100 million gallons of water per year.
Rainwater
Rainwater is collected from the CHWP-2 roof and piped to the Reclaim Tanks in the
basement.
Rainwater collected from campus buildings saves 9 million gallons per year.
5.4 RECLAIM WATER SYSTEM COMPONENTS
Reclaim Water Tanks
Reclaim Water Tanks 1 and 2 are located in the basement of CHWP-2.
Reclaim Pumps
Reclaim Pumps P1 and P2 are located next to the Reclaim Water Tanks.
Reclaim Pump Controls
Manual Controls for Reclaim Pumps P1 and P2 are located to the right of the pumps.
Cooling Tower Basin
The Cooling Tower Basin is located below the cooling towers.
Irrigation System
Reclaim water reduces or eliminates reliance on City of Durham water for landscape
irrigation.
6.0 CHWP-2 RECLAIM WATER CONFIGURATION AND PROCESS FLOW
Reclaim water from AHUs, the creek, wells, and rainwater is collected in the Reclaim
Water Tanks.
When the water level in the tanks reaches 4 feet, the reclaim pumps turn on, sending
water to the CWP2A and CWP2B cooling tower basins.
When the level drops below 2 feet, the pumps automatically shut off.
When the water level in the tanks reaches 4 feet, water is also pumped to the irrigation
system.
7.0 AHU COOLING COIL CONDENSATE FLOW
Moisture laden air passes through the chilled water coil.
The moisture condenses on the coil and is captured in the drain pan.
The booster pump injects condensate into the condenser water line to the cooling tower
basin.
8.0 OPERATIONS MONITORING
Operation of the CHWP-2 Reclaim Water System is monitored through the Control
Room on the top floor of CHWP-2.
The Digital Control System (DCS) provides operators with information on system
operation and control over system parameters.
8.1 PLANT ROUNDS

During an Operator’s routine shift, Rounds are accomplished to record key
information and visually assess Chilled Water System operation.

Each Plant has a Rounds Sheet to be filled out by the Operator.

Each plant has different requirements for plant rounds.

The information is recorded, not only for the current status, but also to record
system trends.
8.2 CHWP-2 DAILY ROUNDS
The following is recorded, during operator rounds, specifically for the CHWP-2 Reclaim
Water System:

Tank #1 Level (inches)

Tank #2 Level (inches)

Reclaim Pump P-1 (ON/OFF)

Speed (HZ/Amps)

Reclaim Pump P-2 (ON/OFF)

Speed (HZ/Amps)

Suction PSI

Discharge PSI
9.0 TYPICAL PROBLEMS ASSOCIATED WITH CHWP-2 RECLAIM WATER

Reclaim pumps leaking
o Most likely cause is packing failure.

Failed Flow Meters
o Most likely cause is failure or clogging of meter.

Flooding of basement
o Most likely cause is sump pump has failed or drain is clogged.

Failed Flow Control Valves
o Most likely cause is clogged valve or failed actuator