| CASE STUDY: Using a utility derived operational goal in optimizing electrical efficiency
AWWA Articles

CASE STUDY: Using a utility derived operational goal in optimizing electrical efficiency

Michael Barsotti, Director, Water Quality & Production
Champlain Water District
Partnership PEAC Chair

Champlain Water District (CWD) has been a Partnership for Safe Water subscriber since 1995.  CWD serves a population of 70,000 in Northwestern Vermont and has received the 15-Year Directors Award under the Partnership Treatment Program.  In addition, in 2014, the District will be eligible for recognition for maintaining the Excellence in Water Treatment Award for 15 consecutive years.  One of the many strengths of the Partnership program is that, once the initial optimization effort has been conducted, maintaining a specific Partnership Award status involves continuing data collection, data submittal and action updates.  “Resting on One’s Laurels” is not what the Partnership is all about.

CWD staff’s extensive participation in implementing the Partnership program to lead optimization efforts at Champlain Water District demonstrated the value of internally developed operational optimization goals.  An example of an internally developed operational goal is using particle count limits as de facto warning limits to assure individual filter turbidity optimization.  CWD’s history with internally developed operational goals was a useful framework for striving to optimize the electrical efficiency of CWD’s High Service (HS) Pumping procedures.  The staff understood that a reasonable internally generated electrical efficiency operating goal would be valuable in prioritizing and aiding pumping operational practices in much the same way that particle count goals had aided in meeting individual filter turbidity optimization.

CWD’s journey and arrival at its internally generated electrical efficiency operational goal involved many efforts by the District’s Electrical & Technologies, Engineering, Water Quality Operations & Wholesale Maintenance Teams.  The efforts of these teams, and CWD managerial support and collaboration with external subject matter experts, were instrumental in bringing a successful internal electrical efficiency goal for the District.  Part of this journey included the following energy efficiency projects:

  • Remote pump station efficiency upgrades
  • Lake water pump station HVAC upgrade using lake water for cooling 
  • Upgrade of 5 High Service (HS) pumps with premium efficiency motors & installation of two (2) variable frequency drives (VFDs)
  • Treatment facility/lake water pump station primary and secondary power upgrades
  • Treatment facility HVAC consolidation and installatino of lake water cooling system for the treatment facility
  • Selecting and implementing energy efficient treatment processes to reduce DBPs under the Stage 2 DBP Rule
  • Air handler adjustment/optimization
CWD’s HS pumping consists of five (5) vertical turbine pumps with 4 of the pumps powered by 350 Horsepower (HP) motors. Two (2) of the HS pumps powered by 350 HP motors are driven by VFDs. The pumps are manifolded together at the treatment facility.  Due to the majority of the demand being on the HS system, the HS pumps at the treatment facility comprise approximately 50% of CWD power use at the treatment facility.

The following optimization efforts ultimately completed CWD’s journey to an internally generated electrical efficiency operational goal:

  • Managing storage tank retention time
  • Initial flow testing of available HS pumping combinations
  • Participating in an electrical load shed program
  • Normalizing monthly electrical efficiency data in KW/MGD (Kilowatts/Million gallons per day)
  • Adopting peak/non-peak pumping practices
  • Developing a maximum KW predictive tool
  • Conducting an Energy Savings Scoping Study (ESSS)
  • Implementing ESSS recommendations
  • Follow-up flow testing of available HS pumping combinations while measuring individual pump KW levels
  • Developing efficiency values in KW/MGD for available pump combinations
  • Observing system pressure tracking with increased pumping on SCADA
  • Normalizing efficiency values of available pump combinations with system pressure to arrive at KW/MGD/psi
  • Multiplying the normalized efficiency power factor by 10 for scalability

The normalized power efficiency factor of KW/MGD/psi X 10 allowed WQ operations personnel conducting pump testing to observe the more efficient normalized power efficiency factor for each pump combination.  This more efficient value was very similar for each pump combination and was set at 4.00 KW/MGD/psi.  By alarming this internally derived goal on SCADA, this efficiency factor is now used as an electrical efficiency operating goal to guide HS pump selection and use while meeting system water quality and operational goals. This is similar to the manner that particle count data guides treatment facility operation.  Reinforcing 4.00KW/MGD/psi as an operating goal continues to increase CWD power use efficiency.

Water utility power use for pumping is significant.  Electrical efficiency is part of utility process optimization and, depending upon the source of power used from the electrical grid, electrical efficiency optimization may lead to a reduced carbon footprint. By examining electrical data and comparing it to pumping rates and normalizing for changing system pressures, CWD is better able to achieve our water quality and operational goals while using power in a more efficient manner.

This article is based upon 2013 Water Quality Technology Conference paper “Improving Power Efficiency While Meeting the Water Quality Operational Goals of a Complex Transmission and Storage System.”

Michael G. Barsotti serves as Partnership for Safe Water PEAC Treatment & Distribution Chair and is the Director - Water Quality & Production at Champlain Water District in South Burlington, Vermont.

Mike acknowledges the following co-authors at CWD: Bruce Bushey – Electrical & Technologies Supervisor, Anthony Higgins – Systems Administrator, Paul Tice – Transmission System Director, Scott Flax – Lead Treatment & Transmission Specialist, Chris Collins – Treatment & Transmission Specialist, Dick Pratt – Assistant General Manager/Chief Engineer, and  Jim Fay – General Manager.

 In addition the following subject matter experts are acknowledged:  Joseph Duncan P.E. – Senior Engineer, Aldrich & Elliot Water Resource Engineers, Inc. Essex Junction, VT;  Scott Barthold, PE – President, Sno.matic Controls & Engineering, Inc., Lyme, N; Tim Perrin – Senior Account Manager, Efficiency Vermont, Burlington, VT.