MWA ‘grossly underestimating’ rain-related sewage spills

February 8, 2010
by S. Heather Duncan | Macon Telegraph

When Bob Hargrove calculated how long it took to fill a 5-gallon bucket with the sewage gushing onto his property, he used it to challenge the Macon Water Authority estimate of the spill’s size.

Turns out, he was right.

The authority had been using a mathematical formula for calculating other types of sewage spills, like those caused by something blocking a sewer pipe.

But spills caused by rain entering sewer lines, usually through cracks and open manholes, caused 67 of the 90 spills the authority recorded last year. Twelve of the 15 “major” spills in 2009 were related to rain.

And those types of spills have always been estimated by “eyeballing” them, Rojas said.

He first realized this when Hargrove complained. Rojas said he asked authority workers how they calculated their numbers. When he heard visual estimates were the method, he asked them to find a more precise formula.

They realized there was a formula outlined in the authority’s own Capacity, Management, Operation and Maintenance Program manual, Rojas said. The manual was published in 2007, with the advice of the state Environmental Protection Division, by a state industry association to which the authority belongs.

“We helped create the manual, and our employees weren’t using it,” Rojas said. “It’s not good. In some respects we’re appreciative that Dr. Hargrove, using his simple method, helped point out we were doing it wrong. At least when we realized it, we admitted it.”

Visual estimates are not necessarily unacceptable, particularly with smaller spills, said EPD officials.

Bill Noell, a manager in the EPD’s permitting, compliance and enforcement program, said there is no single instrument available to measure sewage flow. Volumes can be calculated based on the velocity of
the sewage, the size of the pipe and how full it is.

“It’s not a science,” he said. “It can be very difficult at times.”

When utilities report their spills to the EPD, the agency does not ask them to explain the methods they used to arrive at the estimates, Noell said.

Different methods produce very different totals. For example, a spill on Hargrove’s property after it rained slightly less than an inch in January was estimated at 1.69 million gallons, using the new method.

Another spill at the same spot, after 5 inches of rain fell in two days during April 2009, was estimated at just 45,000 gallons using a visual inspection.

In another example, a dead-end near Lennox Drive was the site of 18 rain-related sewage spills between 2008 and Thursday. Ten were classified as major, but the largest before the authority switched to the new calculation method was 75,000 gallons. The first Lennox spill after the switch: 732,822 gallons.

Estimates questioned before

Several residents, park officials at the Ocmulgee National Monument and The Telegraph have questioned authority spill estimates during the past five years.

“There have been times when they’ve listed something as a minor spill, then when we asked them they came out and re-evaluated it and changed it to a major,” said Jim David, superintendent of Macon’s national monument. “Other times, they say it’s only minor. We don’t really have any legitimate way of knowing if their calculations are correct or not.”

Despite these questions, authority leaders did not fully examine their methods until now.

“I can’t tell you why we didn’t find it in the manual before,” Rojas said. “I guess that makes us look even worse if people were telling us and we said we were right.”

After realizing the error, authority leaders reported it to the state Environmental Protection Division last week, Rojas said.

Noell, at the EPD, asked them to revise the totals from previous, miscalculated spills if enough information is available, Rojas said.However, the method requires evaluating the position of the manhole cover hourly throughout a spill, so revisions will involve some degree of guesswork, Rojas said. Authority staff will try to revise the old numbers as they calculate comparable new spills at the same locations. (Rain-related spills often happen in the same place repeatedly.)

“I don’t know what value it would bring to go back to every hydraulic spill,” Rojas said.

Mark Wyzalek, the authority’s environmental compliance manager, said the authority started conducting weekly water testing of the Ocmulgee River north of the city and at the Otis Redding Memorial Bridge this month to get a better understanding of actual spill impacts.

Potential fines

Revising the past spill totals could lead to an increase in fines for the authority.

The EPD is reviewing the information that the authority provided to the agency, but the EPD isn’t yet in a position to address the question of fines, said Jane Hendricks, an EPD program manager for permitting,
compliance and enforcement. The EPD is satisfied with how the authority plans to handle the spills going forward, she said.

Rojas said he didn’t want to revise the spill totals “on a pro rata (proportional) guess and get more fines.

“All they do when they fine us is take away money from what we could pay for improving our system,” he said.

Adopting the Capacity, Management, Operation and Maintenance program, which includes the method for calculating sewage spills caused by heavy rains, enabled the authority to achieve a special three-year deal with the EPD in 2007. The authority had also seen a marked drop in sewage
spills and spill volume, although it now appears that not all of those volumes were accurate.

The consent agreement meant the authority paid less in fines for sewage spills because it was handling and preventing spills more effectively.

Rojas noted that the consent agreement was based not just on the size of spills, but on the authority’s daily operations and its spending on sewer system improvements.

Today, that includes more than $8 million in planned improvements to sewer lines and pump stations where the majority of the rain-related spills occur.

Wyzalek said in an e-mail that one of the practices in the voluntary agreement “is calculating volumes of sewage spills in a specific manner. This one practice is what MWA had failed to do up until this time.”

The authority goes beyond the norm in reporting spills by posting information about them online, and it reports sewage overflows that don’t reach a waterway.

“I don’t think staff is trying to give us a low number of major (spills),” Rojas said. “If they got it wrong, they got it wrong by mistake.”

Spills in the woods

Hargrove, a retired Mercer professor of chemistry and environmental science, bought 250 acres of “wild land” in 2002 so he could conserve it and plant bald cypress trees there. But small sewage problems in his woods, which are near Sofkee Industrial Park, became larger in the past
year, he said.

Jan. 22, Hargrove led the way to a manhole with sewage spewing out on all sides. Toilet paper and smelly black gunk coated the large clearing, and liquid flowed slowly through the woods toward Tobesofkee Creek.

Fresh tire tracks led Hargrove to believe the authority knew about the spill, but authority officials say they thought sewage had stopped spilling there the day before.

No spill from Jan. 22 has been reported to the state, prompting Hargrove to call the EPD himself after the flow didn’t slacken over five hours.

“We can try to get better information on that and report that spill,” Rojas said.

The problem on Hargrove’s property is caused by heavy flows in the sewer lines that feed the nearby Allen Road pump station, which pumps sewage uphill toward a sewage treatment plant. The authority is beginning a one-year, $2.7 million project to upgrade the pump station, and in a few more years it plans to add another major line in the area to relieve some of the pressure. Rojas said even when it thought the spills were smaller, the authority was being aggressive in trying to improve such problem areas. He pointed out that the Allen Road pump station project as well as the overhaul of the Lennox-Corbin sewer line were planned during drought years.

“We’re doing the right thing,” Rojas said. “You can’t say we aren’t trying to fix the problem.”

Hargrove is glad of planned improvements, but he wants to see faster results.

“Every time we get over an inch of rain, I can look forward to a major spill on my property,” he said.

Rojas said the authority is experimenting with a way to at least reduce the size of the spills by pumping less at an upstream pump station during heavy rains. The large sewer pipe that feeds that station has
room to store more sewage when other pipes fill up. “We did that over the last weekend and we think it helped,” Rojas said, Altamaha Riverkeeper James Holland said he has heard a recent spate of
complaints from Macon residents about sewage spills. He plans to hold a conference with them and a lawyer soon.

“We thought we had this problem cured years ago, but apparently what happened was the drought was simply masking this problem” of leaking sewer pipes, Holland said. “We’ve got to stop this. It’s time something came to a head.”

Information from The Telegraph archives was used in this report. To reach writer S. Heather Duncan, call 744-4225.

YouTube video

Macon Water Authority (MWA) Sewage spilling into Tobesofkee Creek near Hwy 247 in Bibb County, Georgia