A 6-inch diameter natural gas pipeline crosses a canal in Florida. Sheetflow from the adjacent street and high flow events’ impact had exposed the pipeline. 3-in-1 concrete bags had been placed atop the pipeline in an effort to protect it, but the sheetflow and high flow events had removed cover behind the bags. If left unprotected, the site risked further damage due to continued pipeline exposure.
Our Solution
Submar proposed reinstalling 3-1 concrete bags on the banks with additional pipeline erosion control measures. Prior to construction, silt curtain was installed to control sediment in the canal and contain it a few feet away from the water surface. The toe of the bank then was excavated to allow the installation of the geotextile fabric beneath the new 3-1 bags to minimize settlement, and the existing concrete bags were hauled off the site. The project area was backfilled with granular fill and covered with a non-woven geotextile fabric liner. The new 3-1 concrete bags were placed on the bank and conform to the existing bank slopes before and beyond the installation areas to avoid causing eddies. Rebar was driven through the sand-cement riprap to secure the bags. The silt curtain was removed after construction, and curlex and seed were placed on the final grade to ensure streambank stabilization and prevent further pipeline exposure.
