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Environmental Dredging Project

February 27, 2018

Location: Northeast River

Project Overview: Contain hydraulic dredge site contaminated sediments within several work zones utilizing 3,400’ of double-walled TYPE 3 HD curtains to manage site turbidity.

ABASCO Contribution: Turbidity curtain design: manufacture and installation support

  • Type 3 HD with 7’, 10’ and 14’ depths using furling lines
  • Dual 5/16” SS top tension cables & 3/8” HG Ballast Chain
  • 22oz PVC coated fabric and 1’ & 4’ windows with 12 oz/yd non-woven polypropylene with 100 US sieve flowing 75 gpm/ft2
  • Aluminum ASTM Universal Slide connectors with anchor points and ASTM Toggle pins
  • 50’ and 100’ sections using SS grommets at vertical ends with furling lines
  • AS 22 Anchor packages with Danforth anchor, chain leader, ½” poly rope, A-2 Anchor Buoy
  • TB-18 Tow Bridles
  • Lighted Buoys

Project Challenges and Features –

  • Monitored NTU Release: 5 NTU Delta, must remain within 95%
  • Strong winds: 30 – 40 mph
  • Sizable tidal exchange and winter storm surge
  • Strong currents during storms projected and bridge crossing currents
  • Two Nor’easter Storms
  • Dredge activity limited by herring and shellfish migration; fish corridors
  • Project duration exceeded one year
  • Filter window flow arrangement for tidal, rain and storm events
Deepwater Construction Project