21 st West Ave. Pilot Project

Transcription

1 21 st West Ave. Pilot Project Providing a cost effective and environmentally acceptable solution to maintenance dredging in the Duluth-Superior Harbor while supporting the partnership of SLR-AOC delisting efforts. Esther Johnson Project Manager Detroit District - LRE November 2014 US Army Corps of Engineers

2 21 st Ave Pilot Project EA and Coordination for Pilot Project FY13 and FY14 Maintenance Dredging Contract requirements Means and Methods Monitoring Success 2 2

3 Duluth-Superior MN, WI Harbor 3

4 21 st Avenue West Embayment 4 4

5 21 st Avenue Pilot Project 3 year pilot project FY13, FY14, FY15 300,000 cyds Mod 373,00cyds Cost effective, environmentally acceptable, and constructible method of placing O&M dredge material Sediment, elutriate, biological, and bioaccumulation testing 5 5

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7 21st Avenue Pilot FY13 Aug 2013 Nov 2013 = 92,000 cyds Material dredged mechanically and placed hydraulically with turbidity curtain Jun 2014 = ~ 22,300 cyds Mechanical dredging and mechanical placement w/o turbidity curtain 7

8 Scope of Work FY13 Contract Project Description - Navigation channel maintenance dredging of four areas (3, 11, 14 & 16) within Duluth-Sup Harbor: 114,000 CY (contract base w/2 options, based on 2013 condition surveys). 91,700 CY dredged in 2013 due to actual conditions. 22,300 CY dredged in June 2013 to finish contract requirements Deposit dredged material into four designated Placement Areas within the 21st Avenue West Embayment: Design of placement areas are intended to reduce water depths to help promote vegetation growth in support of aquatic habitat. Maintain acceptable clarity of water outside of Embayment with the use of a permeable turbidity curtain to contain suspended material. Final payment for contract: $1,620,400 $120,000 support for turbidity curtain funded by GLRI 8

9 Pilot Year 1: FY2013 Dredging 21 st Ave. W. Pre-Placement 2013 Survey Area 1: Prior -2 to -14 Target: -1.0 Area 4: Prior -10 to -25 Target: Area 2: Prior -4 to -6.5 Target : -1.0 Area 3: Prior -3 to -8 Target:

10 Pilot Year 1: FY2013 Dredging Post-Placement November 2013 Survey & Material Makeup Placement Area 1: Post -1 to -3 Target: -1.0 Placement Area 2: Post -1 to -3 Target: -1.0 Placement Area 4: Post -8 to -21 Target: Placement Area 3: Post -1 to -3.5 Target: -2.0 Placement Area Dredge Area Dredge Material (Schwartz ) Payable CY 1 3 SM / SP - Silty Sand 21, ML - Silt w/ Sand 14, ML - Silt 13, ML - Silt w/ Sand 4, SP - Gravelly Sand; SP-SM - Sand w/silt and some 1,400 Gravel; SM - Silty Sand 14 ML - Silt 18, ML - Silt 2, ML - Silt w/ Sand 1, SP - Gravelly Sand; SP-SM - Sand w/silt and some Gravel; SM - Silty Sand 15,700 Subtotal 91,

11 Pilot Year 2: FY2013 Cont d Dredging Pre-Placement June 2014 Survey (after winter season) 11 11

12 Pilot Year 2: FY2013 Cont d Dredging Post-Placement July 2014 and Prior for FY2014 M/D 12 12

13 Pilot Year 2: FY2014 Dredging July 2014 Oct 2014 = 113,000 cyds Mechanical dredging with hydraulic placement using turbidity curtain Option Material (Area 14) = 57,000 cyds Erie Pier Placement 13 13

14 Scope of Work FY14 Contract Project Description - Navigation channel maintenance dredging of areas (6, 7, 10, 13, 14, 16, 23, 25, 26 & 28) within Dul-Sup Harbor: 164,000 CY (contract base w/ option, based on 2014 condition surveys) 112,000 CY available based on 2014 Priors placed in 21 st Ave 52,000 CY available in Area 14 based on 2014 Priors disposal to Erie Pier Deposit dredged material into two designated Placement Areas within the 21st Avenue West Embayment: Design of placement areas are intended to reduce water depths to help promote vegetation growth in support of aquatic habitat. Maintain acceptable clarity of water outside of Embayment with the use of a permeable turbidity curtain to contain suspended material. Approximate final payment for contract: $2,153,900 $70,000 support for turbidity curtain funded by GLRI 14

15 Pilot Year 2: FY2014 Dredging Area 5: Target: -1.0 Capacity: 150,000cyds Area 5: Target: Capacity: 40,000 cyds 15 15

16 Contract Requirements Constructability Pump and Offloading procedures Curtain Requirements Turbidity monitoring Prior and After Surveys 16 16

17 Transfer Box with Grating and Wash Water 17 17

18 FY2013 Submersible Pump 18

19 FY2014 Hydraulic Pump 19 19

20 Transfer Box Pump Discharge Line 20

21 FY13 M/D Discharge Platform in Placement Area 1 21

22 Discharge Diffuser and Baffle Plate 22

23 Turbidity Curtain 23

24 21st Ave W. View North 24

25 FY2013 Monitoring Efforts Monitoring in 2013 Results of monitoring efforts will help partner agencies to determine design and construction constraints of future restoration efforts with SLR-AOC. Funding for monitoring and evaluation provided by partnering agencies and GLRI. Best management practices (BMPs) using turbidity curtain and baffle plate during construction were effective in minimizing sedimentation and protecting water quality standards Turbidity measurements (NTU) and Total Suspended Solids (TSS) collected during active placement. Focused on how turbidity concentrations decreased from the discharge pipe within the embayment

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28 FY2014 Monitoring Efforts Monitoring in 2014 Modify turbidity sampling plan to evaluate effectiveness of curtain containing turbidity within embayment and limits of turbidity due to dredging. Include sampling at multiple depths to understand how turbidity concentration changes though the water column Focus on collecting project and harbor wide background turbidity levels for in-situ qualitative comparison. Other agency efforts are focused on documenting habitat improvement is occurring to warrant future similar projects 28 28

29 FY2014 Monitoring Efforts 29 29

30 FY2014 Monitoring Efforts 30 30

31 Pilot Project Results 21 st Ave West Embayment provided a cost effective and environmentally acceptable method for placing O&M dredged material. Material can be placed hydraulically and stay in place as constructed to create underwater topographic features. Using a baffle plate as a BMP ensures the energy is dissipated and material settles evenly within placement site, keeping turbidity concentrations higher near the discharge pipe. Turbidity dies down quickly within placement site and can be visually observed, however concentrations can stay higher in deeper depths depending on material being placed. Ranges of turbidity seen within the placement site are similar to background turbidity during storm events and are not detrimental to aquatic life (ex: Walleye eggs and fry) for the limited duration during dredged material placement

32 Project Partners City of Duluth, MN. Duluth Port Authority Minnesota Department of Natural Resources. Minnesota Pollution Control Agency. Minnesota Sea Grant - Univ. of Minnesota-Duluth (UMD). UMD - Environmental / Water Resources. UMD - Natural Resources Research Institute (NRRI). USACE - Engineer Research & Development Center (Ithaca, NY). USEPA - Office of Research & Development (Duluth, MN). USEPA - Region 5, NEPA Implementation Section (Chicago, IL). Wisconsin Department of Natural Resources