Wet Dust Suppression

Coal dust pollution in Southeast Newport News and Lambert's Point are primarily mitigated using wet suppression methods that consist of spraying water, or water with chemical additives, over coal storage piles, railcars, and/or transloading equipment with a system of sprinklers and water trucks. Water application is in theory adjusted based on terminal activity and ambient meteorological conditions. According to a representative from Norfolk Southern, most coal-carrying railcars are sprayed with chemicals when they leave the coal mines, minimizing the dust emissions en route to terminals.

Wet Dust Suppression in Hampton Roads

History

Daily Press: A leading activist for coal dust mitigation in the 1980s, Mrs. Louise Bazemore is photographed displaying the coal dust she cleaned from inside her Ridley Circle home.

1920s: Water suppression of coal dust emissions is mentioned in the record as early as the 1920s, when the Chesapeake and Ohio (C&O) Railroad Company installed a custom pipe system to spray water on coal-filled railcars where and when the cars were emptied through overturning.

1950s: Following pressure by the Garden-Shores Civic League, the City of Newport News hired a chemical engineering firm to measure the amount of coal in airborne particles. This study found that at least in one location in Southeast Newport News 45% of airborne dust was un-combusted coal. In response, the Newport News City Council compelled C&O to install equipment to create a water fog over the coal piers to suppress dust and led Newport News City Council to pass an air pollution ordinance.

The combined mean annual emission rate for both terminals, both the uncontrolled and projected controlled emissions, based on ΣK_t from research by the APCB published as figure 6 in Control of Fugitive Emissions from Open Coal Storage in Newport News, Virginia.

1980s: Community activism and residents' complaints to Virginia Air Pollution Control Board (APCB) led the APCB to conduct additional research on the factors that influenced coal dust emissions and develop a wet suppression approach that was more effective. This research was published in the report: Control of Fugitive Emissions from Open Coal Storage in Newport News, Virginia. As part of this study, researchers developed a mathematical formula for the effective wind forces (K_t) on the terminals' coal piles using readily available meteorological measurements.

$K_t=SP\left(\frac{T}{RH}\right)\left(\frac{P}{\mu \times 1.68}\right)$

SP is the wind speed in miles per hour, T is air temperature in °F, RH is relative humidity (%), P is the air density in pounds (lbs) per cubic feet, and μ is the air viscosity in lbs per cubic feet hours. The constant of 1.68 is the value of P divided by μ at standard conditions of 70°F, RH of 60%, and P of 29.92 inches Hg. The term T/RH reflects the tendency of the coal piles to emit particles when temperatures are high and/or RH is low.

The APCD developed the equation for K_t to guide and optimize wet dust suppression with sprayers in Southeast Newport News. Their 1987 study found a strong relationship between the daily summed K_t (ΣK_t) and the amount of particles measured in the air. Because coal dust emissions are reduced on cloudy, rainy, foggy, and humid days, the APCD developed a weight (F_c) to be multiplied by K_t to include the effects of rain and fog on coal dust emissions. F_c is a value between 0 and 1, with heavy fog (visibility less than 4 miles) or rain (more than 0.3 inches) giving a value of F_c equal to zero, meaning K_t x F_c = 0.

To develop a standardized water sprinkler cycle for both Southeast Newport News terminals, the APCB tested the only recognized wind speed value of 12 miles per hour at which dust may become significant, which was reported in a 1984 study from the U.S. Environmental Protection Agency (EPA) Office of Air, Noise and Radiation, and the Office of Air Quality Planning and Standards. We note that we only found a related report from 1985. This value was used as a starting point to initiate a spray cycle, which would be repeated hourly as long as K_t remained above 12, with a one hour delay between cycles. It is not stated how long the sprinklers remained on per cycle. In a second experiment, if the hourly K_t reached or exceeded 28, hourly spray cycles would be employed as long as this condition existed. If K_t did not exceed 12 on a given day, the sprinklers were turned on at 11:00 am and 2:00 pm in a so-called assurance cycle. In the case approaching extreme weather, the National Weather Service was to provide both terminals with warning information, with the terminals initiating water spraying hourly until K_t fell below 12.

The difference between the uncontrolled concentration of particles based on ΣK_t divided by the number of cycles performed, was used to determine the percent reduction in coal dust emissions per cycle (%R/C) for a cycle applying 24,000 gallons of water.

$\mathrm{\%}R/C=16\times 10^{-0.0010279\mathrm{\Sigma }\times K_t}$

The dust emissions reduction attained (ATT) was then equal to the reduction in coal dust emissions per cycle (%R/C) multiplied by the number of cycles (C).

$ATT=\left(C\right)(\mathrm{\%}R/C)/100$

Today

Despite decades of dust control using water suppression, nearby residents continue to report that coal dust negatively impacts local air quality, outside and in their homes, leaves dust films on outdoor and indoor surfaces, harms quality of life, and requires residents and property owners to bear high air filtration costs. That said, it is commonly held that coal dust pollution in Southeast Newport News was worse before the water suppression sprinkler system was upgraded in the 1980s. Residents also describe seeing sprinklers that are frequently off. There are also reports from residents that the sprinklers are not turned on until winds are very fast.

While the sprinklers are not on at the moment of the photograph, large amounts of standing water are visible at the Dominion Terminal.

The Dominion Terminal now used 79 sprinklers, turned on about four times per day or more depending on the weather, as well as a water truck dispatched to locations not covered by the sprinklers. The Kinder Morgan Bulk Terminals use a system of 44 sprinklers to spray water that suppresses dust emissions from the piles and transloading equipment. In 2022, Kinder Morgan spokesperson Amy Baek claimed the Kinder Bulk Morgan Terminals used 20,000 gallons of water every hour to suppress dust emissions.

Water suppression is argued to be effective at fairly low cost. The terminals in Southeast Newport News and Lambert's Point have fought against other dust mitigation methods, not because they do not work, but because of their associated price tag, even though costs are small as a fraction of the terminals' annual revenue.

Types of Surfactants

In general, dust suppressants should be durable, protective, easy (meaning they do not significantly impede transportation processes), cost-effective, and non-toxic. A variety of formulas are on the market, including oils, waste oils, oil emulsions, latex sealants, lignin derivatives, polyacrylamides and proprietary formations, each with their own drawbacks.

Currently, there is no documentation that can independently verify the projected PM control efficiencies for most of these options.

• Plain or mist water sprays
  • Commonly installed at conveyor transfer points, rotary dumpers, hoppers, and stockpiles.
  • Rely on fine water droplets (typically 10–200 µm) to adhere to dust and settle it out of the air
• Mist cannons or Dry Fog systems
  • Ultrafine droplets (<10 µm) form an airborne “blanket” that agglomerates dust in enclosed areas like hoppers.
• Surfactant‑enhanced sprays
  • Addition of surfactants reduces water surface tension to improve adhesion to fine, hydrophobic coal dust. This method enhances capture efficiency and conserves water compared to plain sprays
• Foam suppression: Foam mixes water, air, and a foaming agent to create a lasting layer that traps dust at high‑impact zones (e.g., conveyor ends, crushers) with minimal moisture addition

• Products like Nbco DustBind, DustBind Plus, DustLock, HAUL‑EZE, and HAULAGE‑DC are polymer or salt-based additives applied via spray. They form a flexible crust over coal to prevent wind erosion and self-heating, especially during rail transport and stockpile storage

Concerns

Some of the chemicals are environmentally toxic and present potential problems if spray run-off and spillage is allowed to fall onto ground unprotected by a collection pad.

Additionally, measuring the efficiency of these solutions is very difficult, and is still a developing process.

Documents

• Han, F. et al. A review of water-based suppressants for coal dust suppression. September 24, 2024.
• Railroads of Port Adopt Coal Sprinkle: Growing demand for Sprinkled Coal Said to Be Made by Trans-Shippers, Daily Press, November 23, 1927
• Ohio Office of Air Pollution Control, Reasonably Available Control Measures for Fugitive Dust Sources (Part 1), September 1980
• Ohio Office of Air Pollution Control, Reasonably Available Control Measures for Fugitive Dust Sources (Part 2), September 1980
• Ohio Office of Air Pollution Control, Reasonably Available Control Measures for Fugitive Dust Sources (Part 3), September 1980
• Ohio Office of Air Pollution Control, Reasonably Available Control Measures for Fugitive Dust Sources (Part 4), September 1980
• City Planning Commission Meeting Minutes, City of Newport News, May 2, 2018
• Email Correspondence between Richard Posner of Dust Solutions, Inc. and Repair Lab Team Member, 2023
• Repair Lab, Coal Dust in Southeast Newport News is a Nuisance and There Are Solution (Corrected), August 2024
• Wituschek E. et al. Coal Dust Control: Recommended practices for loading, unloading and transporting coal by rail. Regional Report No. 86-17. April 1986.