Fine-Mesh Exclusion Barrier System: 7 Years’ Operations

1. Fine-Mesh Exclusion Barrier System: 7 Years’ Operations Entrainment and Impingement Protection for a Desalination Plant Tidal River Intake Andrew McCusker, Mackworth-Enviro Brent Courchene, Stantec Nathan Henderson, Stantec Christian Guelke, Mackworth-Enviro 316(b) Symposium American Fisheries Society 2014 Annual Conference August 18, 2014

2. Today’s Talk What is a Fine-Mesh Barrier System? Where does the technology come from? The Taunton River and TRDP The Project & Site 7 years OM&M Performance Cost Applicability to 316(b)

3. Fine-Mesh Barrier - Technology Basics The basic structure most often includes: Flotation hood – which may incorporate either sealed polyurethane flotation or have polystyrene billets installed onsite; Permeable, filtering geotextile medium or specialized mesh netting. May also be composite material and may contain oil or chemical absorbent sacrificial/replaceable layer; Ballast pocket at bottom, with chain as ballast. For barriers that are to maintain a seal with the bottom, may incorporate an extended impermeable skirt; Structural “skeleton”, -integrated vertical and horizontal members of 10,000 lb nylon strapping as well as the ballast chain through the bottom; Mooring hardware- D-rings or other hardware, both below the hood and at the bottom for securing the barrier in place, top and bottom as appropriate.

4. Fine-Mesh Barrier – Filtration Medium A fine-mesh barrier is effective in reducing entrainment or associated mortality because it has small openings for the water to pass through and, by expanding the area of the intake opening, it operates with a low approach and through-slot velocity Non-woven; 0.150 mm AOS Woven; 0.425 mm AOS Fine Mesh Grid; 1.0 - 5.0 mm

5. Fine-Mesh Barrier – Sizing Aspects • Expands surface area from shore-mounted facility intake • Operational hydraulic head (Velocity and Permittivity) determines loading per unit area • Loading on barrier determines required strength, anchoring and buoyancy requirements • Deeper = > load per linear ft • Greater linear dimension requires more valved air diffusers • TRDP apprx 440 lf, 4 sections, 28 filter panels, deepest apprx 25 ft

6. Fine-Mesh Barrier – Sealing • Any area of unfiltered flow will receive an order of magnitude greater intake flow • Seal to top with flotation collar • Seal to bottom with impermeable skirts, chain ballast and cross-sectional configuration • Seal at ends by various design & structures • TRDP with 15 – 18 in dia polystyrene in flotation collar, double impermeable skirts, seal to shoreline as challenge

7. Fine-Mesh Barrier – Maintaining Structure and Position • Mooring lines to top and bottom hold against intake flow • Inside mooring lines to maintain position in absence of plant flow • Account for current velocities and direction, plant flow, and vertical water column variation • TRDP – Helical anchors, low footprint, installed to design load bearing level

8. Fine-Mesh Barrier – Maintaining Flow • Pressurized air delivery system • Automated • Individually controlled valves to diffusers in panels • At TRDP, shore mounted valve boxes, 3 hose bundles to float distribution boxes to 28 filter panels

9. Initial Fine Mesh Barrier System Development 1996 – 2008 Lovett GS Tidal Hudson River, NY 4 years commercial operation 1600 lf, 52 ft depth max Effective system – 72-95% exclusion Expensive to operate and maintain Air system and control required maintenance and repair ongoing Visual observations plus load cells and water level differential monitoring demonstrated as effective for assessing system integrity

10. Project Background • Planning and permitting for the Taunton River Desalination Plant (TRDP) ongoing since 1994. • 14 miles upstream where the Taunton River dumps into Mount Hope Bay. • Treatment of 10 MGD brackish water from the Taunton River, MA. • 5 MGD per day to communities in SE MA. • TDRP operates in desalination mode when salinity > 5ppt. (July –November). Narragansett Bay

11. TRDP Fine-Mesh Barrier System2008 - Present 16,667 gpm intake and 21,000 gpm brine discharge – Intermittent and tidally dependent 2002 Preliminary design concept – Then approvals and permitting 2007 Detailed design, fabricate and deliver 2008 Initial operations 2014 Year 7 ongoing Low-Impact Anchoring Bi-directional Flow, High-Discharge Systems Shore-Mounted Air Supply System

12. Entrainment Exclusion • Extensive sampling to determine exclusion effectiveness • Result often confusing • Issues include: • No plant flow except for sampling • Lag with river abundances and IS sampling • Eggs become larvae • Late April – early July occurrences overwhelm annual statistic • Spawning fish inside barrier

13. RIS Entrainment Exclusion (eggs and larvae)

14. Annual Exclusion Percent (with caveats) RIS Annual Calculated Exclusion Efficiency

15. Enumerating TRDP Fisheries Impact Equivalent Adult Model (EAM) puts impingement and entrainment into context of actual age-1 fish

16. Fine Mesh Barrier-TRDP System Costs

17. Applicability to 316(b) • Entrainment Reduction • Larger mesh for impingement • Judgment of agencies • Expertise in this room

18. Questions or Comments?