Exclusive: Deadly dam break resulted from Fort Jackson's failure to maintain earthen structure, records show

The U.S. Army found problems as early as 1979 at a Fort Jackson dam that crumbled during a deadly 2015 flood, but it failed to fix some of the problems cited by inspectors through the years, records show.

For the first time, documents released by the U.S. Army Corps of Engineers show the fort didn’t heed warnings engineers previously had made about the Semmes Lake dam before the Oct. 4, 2015, flood.

When the Army did work on the dam, its efforts increased chances the earthen structure would break, records show.

Those documents, obtained by The State newspaper through a federal open records request, don't tell the full story of the broken dam. The U.S. Department of Justice is trying to seal other records that could cast Fort Jackson in a bad light. The State newspaper is challenging that secrecy effort in federal court.

But documents The State obtained under the Freedom of Information Act show a number of deficiencies at the Semmes Lake dam.

According to an April 29, 2016, technical review by the Corps of Engineers:

  • A spillway, or channel, that was intended to release water from Semmes Lake during storms was inadequate for the job. In 1979, inspectors said the spillway was not sufficient to release enough water to relieve pressure on the dam in an emergency. Some repairs were made to the dam through the years, but “inadequate spillway capacity was not addressed.’’

  • For years, federal officials wrongly said the Semmes Lake dam was designed to withstand a stronger storm than the one that blew through Columbia in October 2015.

  • The dam contained broken and corroded equipment. That equipment, which controlled water levels in the lake, was inoperable, making it impossible for the fort to drain Semmes Lake as the massive rain storm approached. Lowering the lake level could have reduced flooding downstream.

“Lowering the Semmes Lake reservoir pool level prior to the … October 2015 storm event would not have prevented the dam from overtopping, but could have reduced the incremental flood depths in the downstream areas,’’ the report said.

In addition to problems contained in the April 2016 technical report, the Corps also said Fort Jackson, in one instance, made structural changes to the dam's spillway that caused it to be less effective at draining water from Semmes Lake.

Spillways are used to release water when lake levels get too high and threaten to wash over the dam — "overtopping" that can cause a dam to fail. At Semmes Lake, however, work crews installed concrete "buffers'' that blocked some of the water from coming down the spillway, according to an April 2013 Corps inspection report.

That "reduces spillway capacity,'' the 2013 Corps inspection report said. "This will put more water load on other features of the dam and increase the chances that the dam with (sic) breach.''

The State newspaper previously had obtained a copy of the 2013 report, but parts of it were blacked out, including the information about the inadequate spillway that the Corps now has released.

'Had they asked' for money for repairs?

What type of maintenance the Army performed on the Semmes Lake dam is of keen interest to many people who suffered losses during the historic rainfall and storm three years ago.

Two people died downstream from the fort when floodwater swamped the lower Devine Street area the morning of Oct. 4, 2015. Neighborhoods and businesses also sustained millions of dollars in damages from flooding downstream from the broken Semmes Lake dam.

The October 2015 rainstorm dumped more than 20 inches of rain on Columbia the weekend of Oct. 3-4, 2015, causing streets to flood and hundreds to flee their homes in boats. The storm knocked out power and the water system in parts of the city for days.

Much of the damage occurred in the Gills Creek Watershed, which includes a series of privately owned earthen dams. The federally owned Semmes Lake Dam was near the bottom of that watershed. It was a 970-foot-long structure built in the 1940s to create a 29-acre reservoir on Fort Jackson. The lake was one of many ponds on the military training base.

According to an April 2016 Corps of Engineers technical review, water from Wildcat Creek, which flows out of Semmes Lake, rose 3.5 feet adjacent to an area that includes part of the King’s Grant neighborhood. Maps included in that 2016 report show parts of King’s Grant would not have flooded if the Semmes Lake dam had held up.

King’s Grant is a gated community adjacent to the base's gate on Fort Jackson Boulevard. More than three dozen people who live in the neighborhood have sued the federal government, seeking up to $20 million in property damages. A trial is scheduled for October if the dispute cannot be resolved through mediation this spring, lawyers for the property owners said.

The report’s findings didn’t surprise Lois McCarty, whose husband died during the flood. But because she’s involved in a legal case, McCarty said she couldn’t say much. McCarty has a pending wrongful death suit against a railroad company that she claims contributed to flooding that killed her husband.

Lisa Sharrard, a Columbia flood consultant, said the April 2016 technical report shows problems with the Semmes Lake dam. But, she added, it also raises questions about whether Fort Jackson or the Corps of Engineers received money to repair the dam.

“Had they asked for federal funding for maintenance and repair after these issues were identified?’’ she asked. “Those are the kinds of questions the report raises that are unaddressed.’’

Officials with Fort Jackson and the Corps of Engineers did not respond to questions Friday from The State newspaper.

'We need to know'

The documents the Corps released shed some light on how the Army maintained the Semmes Lake dam. However, the full story might never be known if the federal government succeeds in persuading a U.S. District Court judge to seal records obtained by lawyers for homeowners in the King’s Grant subdivision.

Those documents include an August 2016 storm event review report; an investigation report, an August 2013 dam inspection checklist, 2017 depositions of Maj. Richard Thomas Childers and Col. Michael Graese, and October 2015 correspondence between Childers and Robert L. Shuck, whose association with the fort was not identified in the legal filings.

One of the biggest unanswered questions has to do with actions taken by Fort Jackson after the 2013 inspection report found major problems that jeopardized the stability of the Semmes Lake dam.

The report found holes in the dam and “out-of-control vegetation.’’ So far, the government has refused to say whether it did anything to correct problems cited in that inspection report.

Jay Bender, an attorney for The State newspaper, said records from the Kings Grant lawsuit should be public.

“It’s our government defending a suit by citizens about the failure of the government to act properly with respect to that dam,’’ Bender said. “We need to know who is right.’’