GEPA investigates environmental impact of Oct. 15 landslide

The Guam Environmental Protection Agency said on Oct. 17 that it will be launching an investigation into any potential ramifications that may have been caused by the landslide that occurred on East Agana on Oct.15.

GEPA said its investigation will include working alongside the Department of Public Works and is not limited to:

What may have caused the landslide;
If construction developments in the affected area were in compliance with GEPA standards prior to the landslide;
Preventing further cliffside erosion and landslides by divert stormwater runoff from above the cliffside and resulting discharges into the Agana Bay; and
Determining the environmental and marine impacts caused by the landslide in the Agana Bay and how to mitigate, cleanup, and restore it in the near future.

GEPA issued a stop work order on the Palisade subdivision as part of the investigation process.

Sediment runoff discolors the waters off East Hagåtña Bay following the Oct. 15 landslide, as environmental agencies continue assessing potential impacts to the surrounding coastline. Photo by Skyler Obispo

On Oct. 15, Palisades developer, Tasi Vista Development, said the cause of the landslide was an aged concrete drainage pipe that failed due to heavy rains in the early morning that day.

“The stop work order requires Palisades Estates to cease further developmental construction, and also requires them to immediately drain or discharge sediment ponds currently filled with runoff water and away from the cliffside and affected area, to ensure no discharge offsite in the event of intense runoff resulting from future rain,” GEPA said in a statement.

GEPA said it will determine whether the preventative measures that were proposed and approved by the agency are in compliance by this week.

GEPA and DPW are also working on a short and long term mitigation plan to divert runoff into the Tiyan Stormwater System. Cleanup efforts are underway by DPW along Route 1 to remove all landslide debris on the roadway to prevent further sedimentation and siltation discharge into the Agana Bay.

A section of hillside along Route 4 in East Hagåtña shows the site of the Oct. 15 landslide, as cleanup and assessment efforts continue to determine the cause and extent of damage. Photo by Skyler Obispo

“Temporary sedimentation Best Management Practice measures are currently underway to prevent further siltation discharging onto the bay,” GEPA said.

GEPA and DPW are working together to determine the cause of the landslide and to assess damage to the Tiyan stormwater system (MS4). The agencies are also identifying the parties responsible for the incident, as well as for subsequent losses, damages, cleanup, and restoration efforts.

“The GEPA Environmental Monitoring section has started conducting water quality sampling of Agana Bay and will continue for some time to monitor [until water quality] standards are being met,” GEPA said. “Plans are underway to engage the Department of Agriculture Aquatics and Wildlife to develop plans for beach clean up and removal of sediment and silt already present from the landslide debris.” mbj