Last month we discussed some of the operational challenges faced by wastewater personnel during cold weather. This article will address thawing and runoff events, limited daylight, and safety issues presented by winter weather.

Large amounts of precipitation water are stored in the snowpack. Most thaw events are high runoff events resulting in high flows to treatment facilities. In addition, ice jams on receiving waters can flood facilities and damage outfall structures. Small thawing events can cause nuisances and slip hazards when the melted water refreezes.

How does an operator prepare for the thaw? Develop a wet weather operations plan and stick to it. Make sure you are maintaining the collection system and working to reduce inflow and infiltration. In preparation for the thaw, make sure CSO points, pump stations, headworks, extra tankage, and treatment units are ready to go. Marking culverts and storm drains in the fall will help to locate them if freeze up should occur. Carefully monitor the weather and keep staff informed.

Another challenge to winter weather is the limited day length. Many parts of Maine receive only 9 hours of daylight in the early winter. The sunlight intensity is much less in winter due to the low angle of the sun in the winter sky. These short day lengths and low intensity limit the outdoor workday, as well as making indoor work more difficult. These factors make proper lighting even more important during the winter months.

Lighting should be checked in all work areas. Clean fixtures and replace bulbs regularly. Add fixtures in inadequately lit areas. Have portable work lighting available for emergency work. Consider using headlamps for task lighting a good idea. You may need to increase work lighting both outside and indoors.

Another issue with limited light that can affect workers is called Seasonal Affective Disorder (S.A.D.). The decrease in sunlight can disrupt our body's internal clock and, in some cases, lead to fatigue, depression, or social withdrawal. Light therapy can help, as well as taking steps throughout the year to keep your mood and motivation steady.

If your plant is considering upgrades, what role can the operator have in designing for cold weather operations? Consider cold weather operations when reviewing project plans. Make sure the design works FOR the operator and communicate any concerns BEFORE construction.

Some common design problems include: No thought about snow removal (dead ends, fencing at driveway edges), no protection for low structures, exposed mechanical systems and work areas, sampling points and lines susceptible to freeze up, condensation issues not being considered, and ventilation problems during cold weather.

Winter operations at wastewater facilities are difficult, uncomfortable, and sometimes hazardous. That is why it is prudent to plan ahead to recognize hazards and minimize risks. These include slip, trips and falls, hypothermia and exposure, overexertion, and dehydration. And falling ice and snow.

Slips and falls are the #1 injury. We work where there is water and cold temperatures, which means lots of ice. Operators must be responsible for their own safety and minimize the risks. Slips into tanks or lagoons in winter can be fatal.

Some tips to preventing slips and falls include keep steps and walkways free of snow and ice, improve traction with gravel or sand, provide good drainage, direct melt water away to avoid icing, remove snow from roof with roof rakes, if possible, wear ice creepers when working on icy surfaces, and remember to use handrails!

Take your time and work and move slowly. Snow and ice tracked indoors will melt and create a slip hazards. Provide non-slip mats at entrances and mop up regularly.

Hypothermia is a condition that occurs when the body temperature drops to a point where muscle and brain function are impaired. This can lead to poor decision-making, which in turn lead to secondary injuries like slips and falls. Signs of hypothermia include shivering, lethargy, and mild confusion. Those suffering from severe cases can become dazed and irrational with slurred speech. Anyone suffering from the effects of hypothermia should seek immediate medical attention.

Factors that inhibit the body’s ability to respond to cold and increase the risk of hypothermia include Inadequate or wet clothing, certain medications, nicotine, or caffeine, and exhaustion and immobility.

Frostbite is an injury caused by freezing of the skin and underlying tissues. First your skin becomes very cold and red, then numb, hard and pale. Frostbite is most common on the fingers, toes, nose, ears, cheeks, and chin. Exposed skin in cold, windy weather is most vulnerable to frostbite. Affected areas appear white and are cold to the touch. Anyone exhibiting these symptoms should seek medical attention immediately.

To prevent exposure-related injury, operators should be trained to recognize symptoms and learn how to treat victims. Prevention includes proper Personal Protective Equipment (PPE), engineering controls, and safe work practice.

Those working in cold weather should use three layers of insulation, paying special attention to hands head and feet. Footgear should be insulated and waterproof, and a change of clothes should be kept available in case you get wet. Did you know that 70 percent of heat loss is through the head? “Feet cold? Put on a hat!”.

Consider purchasing tools with insulated handles to protect hands and fingers. It is best to work with a coworker and have a radio or other source of communications available.

Engineering controls can provide onsite heat sources to shield work areas from drafty or windy conditions and can provide heated shelter in areas where prolonged exposure may occur. Be aware of hazards! Carbon monoxide (CO) is generated by some heat sources, generators, and vehicles, and ventilation is more likely to be inadequate with everything closed in for winter. Signs of CO poisoning include fatigue, headache, and dizziness.

Driving in winter weather requires constant attention to watch for changing conditions. Slow down! Winterize vehicles, batteries, tires, wipers, windshield washing fluid and antifreeze. Secure loads so they don’t become trajectories if you end up in the ditch. 

We think more about overexertion and dehydration in the summer, but they can occur in the winter as well. Operators performing strenuous tasks such as snow shoveling or even walking through deep snow, can cause overexertion, muscle strains and even heart attacks. It’s easy to become dehydrated in cold weather. Remember to work slowly, take breaks, and drink warm liquids, (while avoiding caffeine).

We all tend to cut corners when working in uncomfortable conditions. Don’t rush work. Working in heavy PPE in cold conditions is slow. Allow plenty of time for the job, take breaks to warm up and rest, and most importantly recognize your limits.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) released an alert responding to active exploitation of Unitronics programmable logic controllers (PLCs) used in the Water and Wastewater Systems (WWS) Sector. Cyber threat actors are targeting PLCs associated with WWS facilities, including an identified Unitronics PLC, at a U.S. water facility. In response, the affected municipality’s water authority immediately took the system offline and switched to manual operations—there is no known risk to the municipality’s drinking water or water supply.

According to the CISA website (www.cisa.gov), WWS Sector facilities use PLCs to control and monitor various stages and processes of water and wastewater treatment, including turning on and off pumps at a pump station to fill tanks and reservoirs, flow pacing chemicals to meet regulations, gathering compliance data for monthly regulation reports, and announcing critical alarms to operations. 

Attempts to compromise WWS integrity via unauthorized access threaten the ability of WWS facilities to provide clean, potable water to, and effectively manage the wastewater of, their communities.

The cyber threat actors likely accessed the affected device—a Unitronics Vision Series PLC with a Human Machine Interface (HMI)—by exploiting cybersecurity weaknesses, including poor password security and exposure to the internet. To secure WWS facilities against this threat, CISA urges organizations to:

• Change all default passwords on PLCs and HMIs and use a strong password. Ensure the Unitronics PLC default password “1111” is not in use. 
• Require multifactor authentication for all remote access to the OT network, including from the IT network and external networks.
• Disconnect the PLC from the open internet. If remote access is necessary, control network access to the PLC.   
• Implement a Firewall/VPN in front of the PLC to control network access to the remote PLC. A VPN or gateway device can enable multifactor authentication for remote access even if the PLC does not support multifactor authentication. Unitronics also has a secure cellular based long-haul transport device that is secure to their cloud services. 
• Use an allowlist of IPs for access.
• Back up the logic and configurations on any Unitronics PLCs to enable fast recovery. Become familiar with the process for factory resetting and deploying configurations to a device in the event of being hit by ransomware.
• If possible, utilize a TCP port that is different than the default port TCP 20256. Cyber actors are actively targeting TCP 20256 after identifying it through network probing as a port associated to Unitronics PLC. Once identified, they leverage scripts specific to PCOM/TCP to query and validate the system, allowing for further probing and connection. If available, use PCOM/TCP filters to parse out the packets.
• Updated Dec. 19, 2023:
• Update PLC/HMI to the latest version provided by Unitronics.
• See Unitronics Cybersecurity Advisory 2023-001 for more information.
• See joint Cybersecurity Advisory, IRGC-Affiliated Cyber Actors Exploit PLCs in Multiple Sectors, Including U.S. Water and Wastewater Systems Facilities (published Dec. 14, 2023) for additional technical information and mitigations.
• See CISA's Secure by Design Alert: How Manufacturers Can Protect Customers by Eliminating Default Passwords.

CISA and WWS Sector partners have developed numerous tools and resources that water utilities can use to increase their cybersecurity. Please visit:

• CISA: Water and Wastewater Cybersecurity
• EPA: Cybersecurity for the Water Sector
• WaterISAC: Resource Center
• American Water Works Association: Cybersecurity and Guidance