Smaller MnTAP projects dealing with aeration motors in GreenStep cities have saved those cities between $17,000 and $66,000/year. For larger projects, the Minnesota Division of Energy Resources Guaranteed Energy Savings Program is open to cities to lock in verifiable ongoing energy savings from water/wastewater treatment plant improvements through performance contracting of deep retrofits without capital appropriations.
The 2003 Infrastructure Study, research and pilot work from Minnesota's West Central Initiative, urges communities to address drinking water, wastewater, and stormwater infrastructure needs together in a more sustainable way. The MPCA's Wastewater Infrastructure Needs Survey of June 2017 projected a 2017-2037 need for wastewater infrastructure throughout Minnesota at almost $5 billion.
Create a motor replacement plan for key motors, to at least maintain efficient operation and preferably improve it; utilize utility conservation improvement program for motors.
Upgrade SCADA systems to use existing flow and amperage or kilowatt measurements as a real-time efficiency measure for key equipment.
Review energy use for proposed plant upgrades at current volumes of water treated as well as at design capacity to verify the plant will run efficiently over the range of expected flow rates.
Who's doing it
Hutchinson - 3 star
Date action report first entered:
Date of last report update:
A variety of improvements have been implemented at the Water and Wastewater Plants to reduce cost and waste of resources. These improvements have been made largely out of necessity when pumps and motors fail. VFD's, in-line monitoring that is synced with controls, SCADA controls that track and trend a variety of variables are all used to optimize treatment efficiency as well as reduce power demand and waste.
The Hutchinson Wastewater Treatment Plant has implemented improvements that have reduced the electric demand by 28% as compared to the baseline year of data.
Implementation of DO measuring units and floating aeration units.
Since implementing DO measuring units, there has been monthly energy savings. By improving technology used during the waste water treatment plant Rogers has been able to save money and improve efficiency.
The water treatment plant has four (4) variable frequency drives (VFDs) for the operation of the water system. There is one on each of the two wells and one for each of the high service pumps. The waste water plant has a total of 16 variable frequency drives throughout the plant. The drives run the blowers, mixers and return activated sludge pumps throughout the facility, both plants are using Programmable Logic Controllers for the operation of the systems.
There have been multiple benefits in implementing the VFD’s on pumping applications; providing significant savings in both the short and long term (such as process control for monitoring flow rates and dissolved oxygen level s). Energy savings has significantly increased because the electrical motors are not running at full speed, or stopping and starting, thus resulting in less stress and reduced wear on the equipment. The electrical demand at the facilities has been greatly reduced, along with the maintenance that needs to be completed on the equipment, resulting in the extended life of the equipment. Staff performs monthly, bi annual and annual maintenance on the plants equipment in order to keep the devices running near peak efficiency which prolongs the replacement of the equipment.
Burnsville has Rehabilitation Plan for it's pumps, motors and variable frequency plans, that operates on a 10 year cycle. The city usually buys the most energy efficient parts for replacement. Most often, the city will receive generous rebates, so the most energy efficient parts are also the most cost efficient. The City upgraded it's SCADA system in 2010 and uses kilowatt measurements as a real time efficiency measure. Burnsville is in the process of planning a complete water plant upgrade, which will begin in 2016.
The City recently conducted upgrades to Pump Station #2 per the Engineering study and CIP. Part of the requirements as set out in the contract (see attached excepts of project manual) was to improve energy efficiency of the pump station and better motors.
Project was recently finished and will use SCADA data to review energy efficiency outcomes.
The outcome, as stated somewhat above is to prolong the treatment facilities life. The facility is extremely old, if left neglected serious injury could occur to workers or serious pollution could occur unto the surrounding environment. Hopes are to increase efficiency, increase flow rate, and most importantly reduce the amount of mercury entering the water system.
In 1998, the City of Inver Grove Heights built a water treatment plant, which was upgraded in 2004 to increase the water treatment capacity by 2 million gallons to meet the City's demands.
In 2015, the City completed a total SCADA systems upgrade.
The City of Inver Grove Heights plans and budgets for motor maintenance and upgrades to increase the motors' energy efficiency and durability. Annual motor maintenance checks are completed and used to identify where improvements will be made. The City of Inver Grove Heights has 7 wells that are on a 7 year maintenance plan. In this plan, one well is checked each year. This system maintenance schedule allows the City to reduce energy usage and save cost.
The City of Richfield has 7 wells with motors that range from 125hp to 150hp. From 2005-2007, all 4 250hp high service motors were replaced with high efficiency motors, which are all on soft starts. From 2007-2010, the City replaced all 7 motors with high efficiency motors and installed a Variable Frequency Drive (VFD) at each location. In 2011, Xcel Energy used Richfield’s Motor Efficiency Program as a case study because we had a total energy savings of 375,570 kWh. It is common practice to replace motors with high-efficiency motors whenever replacements are needed.
Our SCADA system was replaced in 2012; we use the trending mechanism to track flows and amperage which allows us to see fluctuations and address them before they become issues.
In 2004, we completed a compressor study. From the study it was determined our 3 current (25hp) compressors were oversized and not efficient. We then worked with Xcel Energy on a customized replacement plan and we now have 3 15hp, high-efficiency compressors.
In 2009, we completed an energy assessment in conjunction with Xcel Energy. From the assessment we implemented the following: 1) Installed motions sensors throughout the water plant. 2) Replaced light bulbs with 28w, down from the 32w. 3) Replacing fixtures with LED ones.
The city uses variable frequency drives on all pumps and replaces motors with the latest most highly efficient technology available.
SCADA systems are used to measure flow and efficiency. The city's water booster station looks to operate at ideal levels.
Old boilers in Silver Bay's water and wastewater treatment facilities have been replaced with more energy efficient boilers. They have switched from propane boilers to natural gas boilers. This change has caused huge improvements in the efficient operation of the facilities.
The City of Albert Lea has a maintenance and replacement budget for key equipment. Organization best practices require equipment to be replaced with the most efficient and effective alternative available.
The city conducts routine maintenance on all pumping facilities and motors. Well pumps/motors are on a 7-year maintenance inspection cycle; WTP pumps/motors are on an 8-year maintenance and inspection cycle; lift station pumps/motors are inspected annually.
The WWTP has an active program of planning and replacing motors and equipment with the most energy efficient, appropriate equipment available. Energy efficiency is considered for all pruchases of replacement equipment
In 2012, after facing a devastating flood, the City chose to update wastewater facilities by installing a new lift station utilizing variable frequency drive technology. This update created a more efficient system being cost effective and energy saving while moving the same amount of volume.
The Utility has a CIP in place that programs regular well and pump/motor rehab work. When energy efficiencies can be gained, older motors are replaced with new high-efficiency motors or variable frequency drives are retrofitted. CIP #SW-01-011 identifies well rehab projects but does not specifically detail energy components.
The wastewater treatment plant employees undertake an extensive maintenance and upgrade program to ensure that the facility is running smoothly and efficiently at all times. Some of the parts and machinery even have weekly maintenance requirements while others are checked bi-weekly or monthly.
Energy efficient equipment is always a strong consideration whenever we make a purchase, construct a new facility, or conduct a rehabilitation project. We also must balance this with compatibility with existing systems, knowledge and experience of operations staff working with the equipment, and product reliability/quality.
sewer upgrades and expansion of city sewer to an area of the city that has failing septic systems and undrinkable water.
The city has initiated the replacement of all pumps, rails and electronics in all of its lift stations. The city budgeted 50% of the costs and applied for and received a matching grant to complete the other 50%. Two of the lift stations have already been upgraded and the other four will be completed in 2012. This improvement is the beginning step to the expansion of sewer and water to an area of the city which has failed septic systems and polluted wells. Our current sustem needed to be upgraded to handle the additional flow of the expansion. The city has increasd its sewer fees to accommadate future regular maintenance. A commitment from IRRR has been made to support the expansion of city water and sewer in the amount of $500,000. The city is pursuing other grant opportunities for another $600,000. The city has also lobbied the legislature to include this in the state bonding bill. This project is scheduled to be in construction in 2013. In 2012, we extended sewer and water to three businesses. One of those businesses emplys a hundred persons, one of the other businesses is a mobile home park. We have obtained funding to extend water lines to residences and businesses in another currently unserved area. This construction will occur in 2013. We have plan to extend sewer to this same area in 2014 in conjunction with a road restructure. As of December 2013, the city has completed a water system expansion to a previously unserved portion of the city that had failing wells and poor quality drinking water. This project has provided clean drinking water and fire hydrants to more than 15 residences and 8 businesses, government offices and a church. The sewer portion of the project is on track for completion in 2015.
The City has been making significant steps in the efficiency of our Waste Water system. During a recent renovation of our plant, all blower motors replaced with more efficient models as well as variable frequency drives were installed on these motors. The drives reduce energy costs by regulating how the motors start and run times. Also the City has been installing soft starts on our key lift stations, the soft starts decrease the high demand that occurred during startup.
We partner with Rich Prairie Sewer and Water for our City Sewer and Water. They budget and plan for maintenance upgrades for future projects, as well as saving for equipment in case of unexpected failures.
The city is currently undergoing a $3 million upgrade to its Sewage Treatment Plant for the reduction of mercury in its discharge. With this new upgrade, there is money put aside for equipment replacement when upgrades or break downs occur. The plant must be operating and in compliance with all regulations by January 1, 2016.
The City performs annual maintenance on all well house facilities and motors. Well motors/pumps are on a 10 year rehabilitation cycle. In rehabilitation, we are implementing Variable Frequency Drives (VFD) for energy efficiency and upgrading our safety controls. Lift station pumps and motors are inspected annually.
The City has been active for the past 20 years in executing a rehabilitation program for each of is production wells. In addition, staff monitor the wells on a weekly basis for proper operation and to look for signs that the motor and pump are operating inefficiently. Indications of inefficient operation prompt immediate action and that well is taken offline and further evaluated for rehabilitation. Out of cycle rehabilitations are accomplished by delaying a well or another capital project scheduled in that fiscal year. Vertical turbine pumps are scheduled for rehabilitation every 8 years and wells with submersible pumps scheduled for rehabilitation every 10 years. One standby well is scheduled for rehabilitation every 13 years based on its infrequent use. A typical well rehabilitation removes the downhole pipe and the motor and pump. The motor and pump are evaluated and either sent away for refurbishment or replaced. The well is televised and any accumulated sand is removed to eliminate the potential for damage to the pump components.