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Manatee County – not one of a kind

News of a possible breach of an abandoned impoundment at a phosphate plant in Manatee County, FL reminds the public again of the silent threat of toxic waste surface pools. The last major similar accident in the US was the Dan River coal ash spill in North Carolina in 2014. How many such impoundments are there, where are they and what do they contain.

The facility in Manatee County that is in the news is a phosphate processing plant called Piney Point Phosphates, which ceased operating in 1999. The plant has an expired hazardous waste permit, and no water permit in the last five years. Its last inspection was in May 1992, seven years before it shut its doors. During its operation, it pumped some 3,000 tons of ammonia and phosphoric acid into its onsite pond. According to Florida state officials quoted in the local press, the water has a pH of 5.7 and has “a little bit of ammonia in it.” The officials said this was safe but added: “Obviously, you would not prefer to go swimming in it.”

At other locations, it won’t be a question of swimming. Many contain highly toxic metals and organic compounds. Accidental seepage or releases from these pools, or a catastrophic failure of an impoundment can shut down drinking water plants for everyone downstream, and poison wide swaths of countryside. The cost to the operating company can be substantial. Duke Energy was fined $5mn by the EPA for gross negligence (the company had revenues of $24bn that year), but that was just the beginning.

Four years later, the company was able to pass on some of the clean-up costs to rate payers, but its shareholders were left with a $350mn tab. Now the company is supposed to dig up all the coal ash residue, which will cost billions, and the wrangling over who will foot the bill is ongoing.

These types of accidents are likely to become more common. With higher temperatures, the atmosphere holds more energy and more moisture, leading to more sudden downpours. Severe storms are occurring more frequently, raising the risk of emergency releases from dams and impoundments, or an outright catastrophic failure of these structures.

There are 2,278 facilities that have reported releasing toxic chemicals into onsite ponds since 1987. Of those, 1,060 release less than a thousand pounds, half a ton, over the entire period. Even though some of the chemicals released are highly toxic, the threat at those facilities is localized and limited. There may be seepage into the groundwater if the lining of the pond is not maintained. The surrounding soil may be contaminated, but the problem is limited in size and scope.

Sites with toxic waste impoundments in the US

It is at the other end of the scale that raises concerns. The top ten facilities, ranked by the amount of released into their on-site ponds, have accumulated a combined 6.4mn tons of toxic chemicals. For the top 100, the total is 9.3mn, while the entire sum for all impoundments is 9.9mn tons. This is a top-heavy problem.

Weighted for toxicity, a different ranking emerges, but the concern is still with the top tier. The top 100 companies discharging into onsite ponds make up practically 100 % of the entire weighted mass of toxic chemicals.

In the case of onsite impoundments, the absolute value of the discharge is the more relevant. The higher the weight of chemicals released, the more water is being used, and therefore the bigger the pond. The three largest sectors in this method of wastewater handling are mining, power generation (the coal ash issue) and metals handling.

Mining has to use water, regardless of the method of ore processing. And the water will produce tailings, a slurry of chemicals and unwanted or un-extracted metals. Much of what contributes to the high toxicity of mining impoundments is the heavy metal content.

The Bushy Creek Mill – a lead mine and processing plant in Missouri – with its impoundments

For the primary metal sector – steel mills and other smelters – it is the materials themselves, the metals, that contribute the most weight, but the arsenic, a byproduct, weighs most heavily in its toxic impact. Copper, zinc, manganese top the list by weight; arsenic, lead and copper are at the top once the toxicity is factored in.

Sector No. of Facilities Total Chemicals in Impoundments Total wtd by Toxicity
Metal Mining 91 7,785,674 10,491,606,793
Electric Utilities 319 1,036,680 221,339,662
Primary Metals 127 645,025 569,876,398
Chemicals 312 274,986 290,640,321
Paper 79 54,366 5,305,527
Other 74 37,321 6,329,467
Coal Mining 80 15,950 7,326,727
Food 128 8,548 69,111
Beverages 40 4,072 515,502
Petroleum 106 2,570 726,620
Nonmetallic Mineral Product 506 2,171 739,887
Hazardous Waste 15 1,478 1,109,987
Textiles 23 1,418 155,597
Fabricated Metals 103 990 1,511,085
Computers and Electronic Products 33 703 18,270
Transportation Equipment 51 497 55,344
Electrical Equipment 23 493 2,649,593
Leather 8 411 14,835
Wood Products 54 341 32,537
Plastics and Rubber 34 264 6,386
Miscellaneous Manufacturing 17 172 32,740
Petroleum Bulk Terminals 21 150 19,919
Machinery 31 64 6,784
Printing 3 8 35
Textile Product 2 2 3
Furniture 6 2 4
Chemical Wholesalers 5 0 63

Given these high numbers, and the increasing risk of spills and breaches, impoundments should be under close supervision. The data however suggests otherwise.

Many of the facilities where the impoundments are located are inactive. Idled mines and power plants have skeleton staff, if any. Early detection of seepage or spill is expensive, and if the facility has been abandoned and the company wound up, it’s often not clear who in practice bears the responsibility for maintenance. The inspection regime by the states and the EPA of these facilities is far from close and comprehensive, again judging by the data. The average time since the last inspection runs into the years.

Sector No. of Facilities Of which Active Facilities not Inspected Avg Days since last inspection
Metal Mining 91 61 47 1902
Electric Utilities 319 220 64 1009
Primary Metals 127 93 65 1062
Chemicals 312 248 161 970
Paper 79 53 11 922
Other 74 63 48 945
Coal Mining 80 62 37 1857
Food 128 103 74 1720
Beverages 40 34 35 796
Petroleum 106 83 62 682
Nonmetallic Mineral Product 506 427 376 1806
Hazardous Waste 15 9 9 936
Textiles 23 17 12 1848
Fabricated Metals 103 80 80 1306
Computers and Electronic Products 33 26 28 596
Transportation Equipment 51 39 35 924
Electrical Equipment 23 20 18 2236
Leather 8 4 6 5529
Wood Products 54 39 20 1516
Plastics and Rubber 34 31 26 1790
Miscellaneous Manufacturing 17 15 13 2085
Petroleum Bulk Terminals 21 16 12 1143
Machinery 31 23 22 1204
Printing 3 3 3
Textile Product 2 2 2
Furniture 6 5 5 2666
Chemical Wholesalers 5 5 4 573

The Manatee County crisis may quickly fade from the news, or it may flare up again if the spill cannot be controlled, or if the radioactive waste that is also stored on the site stars collapsing into the pond, as local officials fear. What won’t fade is the risk of further such occurrences.