York River Treatment Plant Outfall/Diffuser Modifications

Client

Hampton Roads Sanitation District (HRSD)

Location

Yorktown, Virginia

Key Challenges & Project Details

MARINE PORTION

  • Dredge 50,000+ CY and transport to 40% to Shirley Plantation for disposal and the other 60% to Portsmouth, VA for storage as backfill material
  • Drive 35 14 inch square concrete piles (up to 70’ length) in 40’ deep water. Used a custom built pile follower.
  • Fuse 3,000 linear feet of 54” HDPE into 600’ lengths and float into York River. Then, fuse all sections into 1,200’ lengths together and sink into position (center of trench and onto pile caps)
  • Install 54” diffuser section, 380’ in length;
  • Place 361 articulated concrete mats over the pipe for protection
  • Backfill (clamshell and hydraulically) 30,000+ CY

LAND PORTION

  • Install 1150 feet of new 48” DIP (ductile iron pipe) to tie into existing treatment plant outfall pipe
  • Build and set a pipe bridge in place over the Dominion Power Plant cooling channel to hold the pipe