Energy expense in the water and wastewater facilities is often more than half of the total Operations & Maintenance (O&M) cost. The life cycle energy cost of large pumps and blowers can be many times the up-front purchase cost. Pumps installed decades ago can still be in service, but due to wear and primitive controls, can be replaced with new equipment, with energy savings exceeding the replacement cost in a few years.
ECMC has experience and expertise in energy optimization of water and wastewater facilities. During Ed's tenure with Lescure Engineers, he developed a successful partnership with a utility sponsored energy efficiency program named California Wastewater Process Optimization Program (CalPOP). The CalPOP program involved visiting public wastewater facilities, identifying potential energy saving measures, and providing no-cost audit reports, cash incentives, and loans to justify implementation of energy saving retrofits. Fifteen facilities were visited and audited; twenty-two efficiency measures were identified and proposed. Of these, sixteen measures have been implemented. The cumulative annual energy cost savings from all implemented CalPOP measures is about $400,000.
For a some of the successful projects, the agencies contracted directly with Lescure Engineers for final design services for the upgrades. This required development of plans and specifications, suitable for public bidding. This allowed a continued focus on energy optimization through the entire design process, which tended to produce the greatest savings.
Final design for pumping systems upgrades involved optimization of new pumps and variable speed drives. This is approached by an integrated model, derived from actual operational data. From this model, pump specifications, piping and control design, and a process control narrative (describing pump sequencing and speed control) were developed. A case study of optimized reclaimed water pump stations for the City of Santa Rosa is here.
The City of American Canyon wastewater facility in Napa County had a very successful energy optimization outcome. We were fortunate that the facility management staff had great conceptual plans for improving the treatment processes, which we took to final design to bring the project to fruition. The project became a feature article in the Water Environment & Technology journal; the reprint is here.