We are committed to protecting air quality, reducing water consumption, and reducing our waste in order to protect our environment.
Air emissions from our wood products facilities are generated primarily from the combustion of fuels to generate energy. Combustion of residual wood in boilers that produce steam energy for use in the kilns to dry lumber produces combustion-typical emissions such as carbon monoxide (CO), nitrogen oxides (NOX), sulfur dioxide (SO2), Hazardous Air Pollutants (HAPs), and particulate matter (PM). When drying lumber in a kiln, wood extractives in the form of volatile organic compounds (VOCs), HAPs, and PM (formed from the condensation of VOCs) are released. The air emissions are limited under several federal and state regulatory programs including the National Emissions Standard for Hazardous Air Pollutants (NESHAP) and New Source Performance Standards (NSPS). The performance standards created by these rules are implemented at our facilities in regulatory permitting programs that establish source-specific operating conditions. These permits guide our facilities to meet the regulatory performance standards and prevent degradation of air quality.
We measure and report air emissions at each of our facilities and monitor compliance with emission limits for each source and emission type established in our Renewable Operating Permits. Stack emissions from larger sources like wood-fired boilers are measured by qualified third-party testing companies on a set schedule defined in our permits. The data collected during the tests are used to verify compliance with short-term (typically hourly) emission limits for select pollutants and are used to develop conversion factors to continuously track compliance against longer-term (typically monthly or annual) limits. Continuous monitoring systems are also used to measure the opacity of stack emissions as a surrogate parameter for particulate emissions. Industry accepted conversion factors are used to characterize emissions from smaller sources and operating parameters are established to ensure their air quality impacts are minimized. Data integrity is monitored continually and is reviewed each quarter. Internal audits are also conducted every two years to verify that the site compliance monitoring requirements are being met.
We evaluate the operation and maintenance of all our emission sources and their associated control devices. Proper design, operation, and maintenance of the production equipment minimizes emissions and is an important part of our air quality commitments. Facilities also utilize cyclones and baghouses to control particulate emissions. In addition, our St. Maries, Idaho plywood facility operates special pollution control equipment to satisfy requirements under the NESHAP regulations, known as Maximum Achievable Control Technology (MACT). Exhaust from the heated zones of the plywood veneer dryers is collected and routed to a regenerative catalytic oxidizer (RCO) where more than 90% of the hazardous air pollutants in the exhaust are oxidized into water vapor and carbon dioxide.
Our wood products facilities use little process water in manufacturing operations. Water is obtained from surface water, groundwater, and municipal sources and is used principally for watering log decks, saw cooling, make-up water at the boilers for steam production, and fire protection. Water withdrawals are minimized through extensive reuse and recycling, especially at the log deck. What little water is discharged is first sent to settling ponds for solids removal prior to being released. Water loss across the facilities is mostly due to evaporation from log watering activities.
Discharges of water are monitored under two permit programs. The National Pollutant Discharge Elimination System (NPDES) is the permitting program that covers discharges of both wastewater and stormwater in the U.S. This wastewater permitting program allows for only certain types of discharges, establishes monitoring requirements, and sets discharge limitations. In 2021, PotlatchDeltic had NPDES wastewater discharge permits at St. Maries, Waldo, Warren, and Ola because these facilities occasionally discharge to surface water. The MSGP program establishes monitoring requirements and discharge benchmarks for stormwater to protect water quality.
The NPDES permits have parameter limits and the MSGP permits include benchmarks for pollutants such as zinc, chemical oxygen demand (COD), and total suspended solids (TSS). NPDES permits have set monitoring regimes that include weekly, quarterly, semi-annual, and/or annual sampling for various parameters. Stormwater monitoring occurs with a qualifying precipitation event that results in runoff. Sampling is conducted by our on-site environmental managers or by qualified environmental consultants. As required, we submit the data to the appropriate regulatory agency within a timeline defined in the permit. NPDES permits can have additional immediate notification requirements if a limit is exceeded, and the MSGP permits have requirements to develop corrective actions if a benchmark is exceeded. The MSGP program requires additional routine site inspections to confirm proper function of stormwater controls. Periodic internal audits are conducted to verify that the required inspections, corrective action planning, and reporting are being followed.
Water is relatively abundant at all our locations. Two of our Arkansas facilities, Warren, and Waldo, however, are in critical groundwater areas due to reliance on the Sparta Aquifer. Total water sourced at Warren was 97% from municipal water and 3% from groundwater, however, municipal water supplied to Warren is partially sourced from the Sparta Aquifer. Total water for Waldo was sourced 68% from groundwater and 32% from municipal water. Municipal water supplied to Waldo is surface water sourced from Lake Columbia.
Wood residuals constitute most of the waste from our wood products production. Approximately 81% of residuals generated are sold for a wide range of end uses, with the remainder used internally for energy. Wood ash is also generated from burning wood residuals for fuel in the boilers. In many of our locations, wood ash is land applied for soil amendment as a soil liming substitute in agricultural and silvicultural applications. This application provides a natural means of increasing alkalinity while supplying certain micronutrients that help plants thrive.
The remainder of our wastes principally consist of a range of non-hazardous wastes which are either reused, recycled, or sent to landfills. The primary non-hazardous waste streams generated by our wood products facilities, other than wood residuals and wood ash, include trash, industrial waste, scrap metal, cardboard, and universal waste.
The final disposal method for this waste is done by a licensed third-party treatment and disposal facility and involves refining the waste liquid to recover useable solvents prior to burning for energy recovery. The steel aerosol cans are recycled after they are emptied.
Universal waste is also generated at our facilities and includes materials such as fluorescent and HID lamps, mercury-containing equipment such as thermostats, and certain types of batteries. These wastes are sent to licensed universal waste handling facilities for recycling. All wastes are stored, recycled, and transported in compliance with applicable laws. We are committed to minimizing hazardous waste.
Each facility has recycling and waste reduction programs in place. Increased emphasis over the past two years has resulted in an over 300% increase in recycled materials across the Wood Products Division.
During 2021, our wood products facilities completed several projects and initiatives that reduced air emissions. The examples below represent some of the continuous improvement actions taken to enhance our compliance reliability and reduce emissions.
Updated Boiler Management System: We updated our boiler data management systems at two of our mills, Bemidji, and Gwinn. These upgrades improved data collection, data completeness, and data feedback loops. Data collection is important because certain events such as equipment upsets and power outages can result in small but cumulative data gaps. Data feedback loops are also important. Boiler operators monitor many data points to maximize combustion efficiency, which improves energy efficiency and reduces air pollution. Improving data feedback loops allows boiler operators to further increase efficiency.
St. Maries Wood Stove Changeout Initiative: The City of St. Maries in Idaho has undertaken a multi-party effort to improve local air quality, which is near the National Ambient Air Quality Standards, or NAAQS, limit. This is primarily due to the tightening of the air quality standards over time and because the area is prone to natural air inversions which can trap particulate matter. The City of St. Maries and other local leaders, including PotlatchDeltic, are implementing local solutions. Part of this effort is changing outdated inefficient residential woodstoves to new models with much greater combustion efficiency. This cuts trips to the woodshed and reduces air pollution from woodstoves during cold winter months when there is limited air circulation in the mountainous terrain. PotlatchDeltic donated $20,000 in 2021 to this program, so that qualifying residents could receive free or very low-cost replacements for outdated woodstoves. This resulted in additional woodstove replacements.
St. Maries RCO33 Improvement: We completed several projects at our plywood mill in St. Maries to improve the efficiency of the Regenerative Catalytic Oxidizer (RCO). The RCO controls HAP and VOC emissions from our veneer dryers. The RCO burns propane to oxidize greater than 90% of these emissions into CO2 and water vapor at high temperatures. The catalyst in the RCO results in a more efficient process by lowering the temperature threshold necessary to achieve this high level of emissions control. We installed a fresh catalyst, upgraded the insulation, and completed other mechanical improvements during a project in 2021. This major equipment overhaul improved the RCO’s energy efficiency, and the new catalyst reduced the temperature threshold, lowering propane consumption and therefore greenhouse gas emissions, while ensuring 90% plus control of emissions from the veneer dryers going forward.
During 2021, our wood products facilities completed several projects and initiatives that reduced water usage or improved water quality. These projects and initiatives, among others, are examples of some of the continuous improvement actions taken to reduce water usage, improve our compliance performance, and reduce pollutant discharges.
St. Maries Complex Stormwater Upgrades: We continue to improve our stormwater system at our St. Maries facility. In 2021, we installed additional settling basins, expanded the capacity of an existing settling basin, and added in rock check dams to increase the residence time within each stage of the settling basin. This increased residence time allows suspended solids to sink out of the water column. We also improved water routing to ensure maximum efficacy of our stormwater controls. Our technical staff and our consultants worked with the Environmental Protection Agency (EPA) and the Coeur d’Alene Tribe on the renewal of our water permit at the St. Maries Complex. This technical work ensures that any water discharge meets federal and tribal standards for water quality. This work to make additional improvements has continued into 2022.
Paving: Paving areas at our facilities creates a smoother surface for equipment, reduces fugitive dust emissions, and reduces stormwater contamination. It allows us to better manage stormwater and reduce TSS, a stormwater contaminant. Appropriate grading of the pavement guides stormwater flow into treatment areas, and it allows us to use street sweepers to keep the pavement clean and prevent TSS loading in stormwater. It also reduces the need for other surface treatments that can lead to stormwater contamination. In 2021, we added pavement at our St. Maries, Bemidji, and Gwinn facilities. We evaluate water flow during storm events to identify areas of highest priority for these paving opportunities.
Bemidji Log Sprinkling: Wood products facilities often utilize sprinklers to provide wet decks for log storage to prevent the drying and damaging of logs stored for long periods over the summer. During the summer of 2021, our Bemidji facility managed log inventories efficiently to prevent the need to run the sprinklers in the log yard. This active management of log flows greatly reduced the water usage by Bemidji in 2021.