Special Report: Danger levels upgraded for several Horry, Florence county dams

Pee Dee

FLORENCE COUNTY, S.C. (WBTW) — A handful of Florence and Horry county dams have been upgraded to higher hazard classifications during inspections over the last few years, according to documents from the South Carolina Department of Health and Environmental Control.

The inspection records — obtained by News13 through a Freedom of Information request — detail the potential hazards dams pose to their local communities if they were to break, along with condition ratings and a list of maintenance items required by the state.

Of 11 dam inspection ratings in Florence and Horry counties, five were rated as being in “poor” condition, five were rated as “fair” and one was not rated. The records were all for dams rated either as posing a “high” or “significant” hazard to their surrounding areas if they were to break.

A “fair” condition means that there are no existing issues that would lead to a dam failing in normal conditions, but that it might be affected if there’s a rare or extreme natural event. Owners are asked to watch their dam for deterioration that could cause it to fail and to pay special attention to seepage and how clear the water is.

“Cloudy/muddy water is an indication that soil is being removed from inside the dam, creating potential voids through the dam that can ultimately lead to dam failure,” the inspection documents read.

A “poor” rating means the dam might fail under natural events that could realistically occur, and that fixes are “necessary.”

Owners must then submit photos to DHEC to show that the repairs have been made.

The most common required repairs listed in the inspection documents include fixing or maintaining erosion and removing vegetation from the area around the dam.

DHEC has placed an extra emphasis on dam conditions following Hurricane Matthew, Jill Stewart, the director of the Dams Safety and Stormwater Permitting Division at DHEC, told News13. Since then, the organization has placed engineers at six regional offices in order to be close to the dams, become familiar with them, and have access to private dam owners who can ask questions.

“A lot of what they do is education,” Stewart said. “One of the biggest jobs we’ve taken on since 2015 is really training and instilling knowledge in our dam owners about how their dams work, what responsibility they need to take in maintaining their dams, and reminding them how to be in communication with us — if they see something that’s happening at their dams that they’re concerned with, that they know how to reach out so we can investigate that.”

Stewart said more frequent inspections lead to better dam conditions. She said that a “fair” rating still means a dam is in pretty good condition, and that the bar for “satisfactory” is very high.

She said the state’s constant growth is leading to more dams being reclassified to higher hazard levels.

Dams that have been reclassified within the last few years include

  • Livingstone Lake Dam in Horry County, which was rated as “fair” in its most recent inspection, was raised to a “high hazard” class. The hazard level was raised because of multiple homes in the area and a road that sees more than 400 cars a day.
  • Lower Heather Lakes Dam in Horry County, rated as “fair,” was raised to a “high hazard” class because it could potentially impact Highway 17.
  • Graham Mill Pond Dam in Horry County, which was listed as “not rated,” was increased to a “high hazard” class because it had the potential to affect Vaught Road and Bud Graham Road. Both roads see at least 400 vehicles a day.
  • Forest Lake Dam in Florence County, rated as “fair,” was moved to a “high hazard” class because it could impact structures downstream.
  • Lower Chestnut Lake Dam in Horry County, rated as “poor,” was raised to a “high hazard” class because a failure could affect structures and undisclosed major roads, according to inspection documents.
  • Canal Ind Pond Dam in Florence County, rated as “poor,” was raised to a “high hazard” class because it had the potential to overtop an undisclosed popular road immediately downstream.

Horry and Florence county’s dams listed as high or significant hazard classes, along with their ratings during their last inspections, are listed in the table below.

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