Wet Dust Suppression

Wet Dust Suppression in Hampton Roads

Mrs. Louise Bazemore is photographed displaying the coal dust she cleaned from inside her Ridley Circle home. Photograph by Michael Dillard.

Coal dust pollution in Southeast Newport News and Lambert's Point is 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 adjusted based on terminal activity and meteorological conditions.

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 installed a custom pipe system to spray water on coal-filled railcars when the cars were emptied by 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 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 pier to suppress dust and led the 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 State 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 was driven in large part by residents of the nearby Harbor Homes, Dickerson Courts, and Ridley Circle.

The APCB's 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 square 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 2116 lbs per square feet. 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. The 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 of 0 or 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. (Note, only a related report from 1985 could be found.) 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 an 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 sprinkler system was upgraded in the late 1980s. Residents describe seeing sprinklers that are frequently off and/or not turned on until winds are very fast.

The Dominion Terminal Associates facility now uses 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 to suppress 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. A record has not been found as to when or if the terminals transitioned away from the spray cycles developed by the APCD in 1987.

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 cost. However, relative costs are a small fraction of the terminals' annual revenue.

Water Quality

While the sprinklers are not on at the moment of the photograph, large amounts of standing water are visible at the Dominion Terminal Associates facility in Southeast Newport News.

What happens to the large volumes of water sprayed on to the coal piles? At Dominion Terminal Associates, coal pile runoff and storm water drain into treatment ponds where coal settles out before being discharged into the lower James River. Inspections by staff at the Virginia Department of Environmental Quality (VA DEQ) identify spills of oil and fuel from the equipment and vehicles that also migrated into the discharged water. The VA DEQ also notes that this region of water is impaired for aquatic life such as fish and submerged vegetation. This can also degrade the odor and appearance of the shoreline thus impacting water recreation. There are many impervious surfaces within the terminals. If these surfaces are not kept clean, heavy rainfall can cause untreated runoff from surfaces to enter waterways or nearby neighborhoods.

Chemical Additives

In some instances, chemicals are added to water used for dust suppression. The chemicals include oils, waste oils, oil emulsions, surfactants (soaps), latex sealants, lignin derivatives, polyacrylamides, and proprietary chemicals. There are products like Nbco DustBind, DustBind Plus, DustLock, HAUL‑EZE, and HAULAGE‑DC that are polymer or salt-based chemicals added to water sprays. There is no documentation to independently verify whether adding these chemicals to water spays improves dust mitigation.

It is unknown whether Dominion Terminal Associates, Kinder Morgan Bulk Terminals, or the Norfolk Southern Pier 6 Terminal uses chemical additives as part of water suppression. 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.

Concerns around chemical additives are primarily that they may be environmentally toxic.

Documents

• Han et al., A Review of Water-Based Suppressants for Coal Dust Suppression, International Journal of Coal Science & Technology, 12, 47, 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 et al., Coal Dust Control: Recommended Practices for Loading, Unloading and Transporting Coal by Rail, Regional Report No. 86–17, April 1986