New Sullivan's Island Elementary School won't strain sewer plant

  • Tuesday, July 16, 2013

The Sullivan's Island Water and Sewer Department constantly works to identify and correct sources of inflow and infiltration, also known as I&I. This cracked pipe photo was taken March 25, 2009. COURTESY OF GREG GRESS

Accusations by a group of concerned Sullivan's Island residents that the island cannot handle additional water and sewer flow from Sullivan's Island Elementary School – when it opens in the fall of 2014 – are not true, according to Water and Sewer Department Manager Greg Gress.

The island's wastewater treatment plant flow is permitted at 570,000 gallons. With a Department of Health and Environmental Control (DHEC) formula of each student using 15 gallons per day, the total school's approximate impact on the plant will be 0.6 percent (500 students x 15 gallons = 7,500 gallons / 1.2 million for highest amount of rainfall inflow on plant = 0.00625). The plant has supported the school in the past, before Sullivan's Island Elementary was moved over the bridge into Mount Pleasant. The additional approximated increase of 100 students in the new school, which will be bigger than ever, represents 0.03 percent (100 students x 15 gallons = 1,500 gallons / 570,000 permitted gallons = 0.0026).

“The treatment plant and the collection system, for the most part, was built in 1968,” Gress said. “So, whatever was here (infrastructure) was factored into the capacity of the treatment plant. Whatever the population was at that time was already factored into the 570 (thousand gallons) of the treatment plant.

“The only additional flow that we're talking about is the 100 kids. It's 1,500 gallons. We looked at what the impact was going to be. We did some improvements to the water line. On the sewer side, what we did was installed a manhole. Instead of the flow going through a pump station, we installed a manhole and diverted it to come straight to the plant. It alleviated any impact on that pump station.

“What the impact is to the school, we've pretty much taken care of already.”

Mayor Mike Perkis has been involved in the decade-long efforts to come up with a town water and sewer capital plan covering five-10 years. “This point that the school is seriously impacting our sewer system is completely incorrect,” he said, “and is irrelevant to what we want to do in our capital plan.”

Perkis stressed that it is “irrelevant” because the impact is minimal. “The idea that the school is being rebuilt is completely coincidental to the approach we're taking (on the drafting of the capital plan),” he added. “It had nothing to do with it. Why? Because it doesn't affect it.”

In a letter to the Moultrie News, which was signed by 12 Sullivan's Island residents and titled “the vocal minority (49.3 percent) was right,” referencing the votes for outgoing mayor Carl Smith, the group wrote that the community has been “misled about the impact of a 500-student elementary school on island infrastructure.”

The letter notes that the wastewater treatment plant has had four overflows of inadequately treated sewage in the past 10 months. Gress acknowledged that this is true. He has to report those statistics to DHEC. On June 7, Station No. 19 had a sanitary sewage overflow (SSO), which is different from a sewage spill. Last year on Rifle Range Road, a main sewer line ruptured, causing raw sewage to spill into the surrounding communities. This is not what happened at Station No. 19.

Gress estimated that the SSO contained less than 1,000 gallons – compared with the daily estimated flow of 570,000 gallons at the plant.

Perkis, using statistics from the DHEC website, noted that in the past 90 days, Charleston Water Service reported three SSOs, Mount Pleasant had two, North Charleston had two, Florence had two and Sullivan's Island had one. Effluent violations means fully treated wastewater has exceeded the permitted amount. “Is it something we want? Absolutely not,” Perkis said. “It is a big deal, because we don't want it to happen, but it's not unique.”

Perkis, Gress and town administrator Andy Benke all emphasized that the most pertinent problem on the island is dealing with inflow and infiltration sources, also known as I&I.

“The town has taken more of an inductive approach. We see I&I as a problem. We've looked at all these problems that create this,” Benke said. “I think what that other group is doing by bringing this school issue into it, they've taken more of a deductive approach. They focus on a premise that the school is going to cause more of that.

“And it kinda fits if you think of it deductively like that. But, when you look at the whole picture, and you look at it inductively across the whole island, this – the flow issue – is a result of all of these different things, not just the school. It's only going to add three one-hundredths. It's just not the problem.”

The water and sewer capital plan, which Perkis said is months away from having a final draft, would cost about $6 million. While surrounding communities, like Mount Pleasant, have impact fees assessed when building new infastructure, Sullivan's Island doesn't have those because growth isn't as common. So, the town is having to be creative when looking at options to fund the project. Perkis said Sullivan's Island will seek out federal and state financial aid and will prioritize the plan's projects accordingly. “You tell people you're going to put a new park in, going to fix a beach access path or put in new tennis courts – it's pretty glamorous,” Perkis said. “You tell people you want to put aside money to fix your sewer system – it's not something governments typically do, especially in tough times. We're pretty proud that we've faced this issue. Now, we're taking the next step in the process.”

Also in the letter from concerned residents, the group noted that environmental assessments of the future school were not available. Perkis said eight regulatory agencies either approved or regulated school plans. Those assessments would be found with them, not the town.

Fight against I&I

Mount Pleasant Waterworks Commission approved a rate increase for customers that will help the I&I battle. The first part of I&I is inflow. Sources of inflow include faulty manholes, connected foundation drains, gutter drain connections and uncapped cleanouts. These are incorrectly, and in some cases illegally, causing direct inflow to sanitary sewer main lines. The other “I” stands for infiltration. Sources of infiltration include tree root intrusion into a side sewer, cracked or broken pipes, deteriorated manholes and faulty lateral connections. Small cracks can quickly become large cracks and the amount of infiltration can spike inflow statistics.

Gress has numerous line charts tracking Sullivan's Island total plant inflow numbers. Potential inflow and infiltration sites are constantly monitored. Perkis said, as of last week, the recent rain occurences are equal to about 15 inches above normal. The Sullivan's Island Water and Sewer Department needs prioritizing. “It's getting worse, there's no question, but we've been working on it,” Gress said. “We just need to up our game a little, and that's what the big capital improvements plan is now here for.”

For more information, check out the extra notes and quotes that didn't make the final print product. Those are available here.

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