Less than 8 feet finished water depth. 4-Foot Cap 3-Foot Cap Foot Cap. 4 Ft

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Spencer Gilbert
6 years ago
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1 Herbivorous Animals Consuming Plants & Sediment Piscivorous Wildlife Consuming Fish Insectivorous Wildlife Consuming Emerging Aquatic Invertebrates Burrowing Organisms Contacting Contaminated Sediment Swimmer Ingesting & Absorbing Water & Sediment Fish & Wildlife Consuming Aquatic Invertebrates & Sediment Humans Exposure Pathways Human Wading & Consuming Fish Piscivorous Wildlife Waterfowl Contaminated Sediment Insectivorous Wildlife Water Plants Benthic Invertebrates Invertebrates Water Figure 1-8 Exposure Pathways of Interest SLRIDT Site Duluth, Minnesota Fish Sediment Herbivorous Animals Waterfowl Consuming Aquatic Plants & Sediment Fig 1-8 Risk Pathways.ppt 11/19/03 KU MC Sediment SERVICE GROUP

3 Figure 3-2 Cap Thicknesses CAD Less than 8 feet finished water depth SERVICE GROUP Greater than 8 feet finished water depth 5-Foot Cap Environmental Media 4-Foot Cap 3-Foot Cap Foot Cap Environmental Media Root Barrier BAZ 5 Ft 1 M BAZ 4 Ft Environmental Media BAZ 3 Ft 0.5 M Environmental Media BAZ Ft IZ IZ IZ IZ Contamination Contamination Contamination Contamination BAZ = Bioactive Zone IZ = Isolation Zone If areas are demonstrated to have downward gradients, the IZ may be excluded.

as reported does not include 4 foot thick sand cap.

4 Figure 3-3 Cap Settlement in Stryker Bay 4-Foot Cap Sand Silt Peat Surcharged Anchor Memorandum #1 April 18, 2003 Note: Surcharge thickness as reported does not include 4 foot thick sand cap. Sand Silt 3 & 4 Feet 4 Feet Of of Settlement Peat Based on Anchor Memorandum #2 dated May 1, 2003

5 Figure 3-4 Shallow Sheltered Bays Ranked by Median Depth (feet) Including Existing and Capped Stryker Bay Depth to Sediment (feet) Radio Tower Stryker with In Situ Cap North Rask Munger Stryker 4'- 3' Cap with Surcharge Kingsbury Mud Lake Existing Stryker Bay Bay Figure 3-4 Median Depths of SSBs xls

6 Figure 3-5 Summary of Alternatives Previously Evaluated SERVICE GROUP 1997 Alternatives Screening Report 1. No Action 2. Capping In Place 3. Limited Dredging/CAD in Slip 7 4. Dredging/Stryker Bay CDF 5. Dredging/Slip 6 CAD 6. Dredging/Slip 7 CAD 7. Dredging/Stryker Bay and Slip 7 CADs 8. Biotreat In Place 9. Dredging/Thermal Treatment 1998 Feasibility Study 1. No Action 2. Capping In Place (six inches) 3. Dredging/Thin cap/cad in Slip 7 4. Dredging/Thin cap/stryker Bay CDF 5. Dredging/Slip 6 CDF 6. Dredging/Slip 7 CAD 7. Dredge/Off-Site Disposal 1999 FFS and Supplemental DAR 1. Wetland (Thick) Cap In Place 2000 Agreement and DGR 1. No Action 2. In Situ Cap 3. Dredge/On-Site Disposal (Slips 6&7) 4. Dredge/Off-Site Disposal 2003 Focused Feasibility Study 1. No Action 2. In Situ Cap 3. Dredge/Cap Hybrid 4. Dredge/Off-Site Disposal Note: Red Alternatives carried forward to next step FFS = Focused Feasibility Study DAR = Detailed Analysis Re;port DGR = Data Gap Report

9 Figure 3-8 In Situ Cap Schedule ID Task Name Duration 1 Complete Design & Permitting 0 days 2 Bidding and Contractor Selection 54 days 3 Mobilization 30 days 4 Dredge WI Area 10 days 5 Stryker Bay Cap - Hydraulic placement (154,494 cy) 49 days 6 Slip 6 Cap- Mechanical placement (54,864 cy) 18 days 7 Slip 7 Cap - Hydraulic Placement - Shallows (65,405 cy) 21 days 8 Slip 7 Cap - Mechanical placement (28,633 cy) 9 days 9 Armor Slips 6 and 7 (32,478 cy) 11 days 10 Armor Mouth of Stryker Bay (3,793 cy) 2 days 11 Place Environmental Media in Stryker Bay (30,460 cy) 10 days 12 Place Environmental Media in Slip 6 and 7 (17,822 cy) 6 days Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 3/15 13 Demobilization 0 days 10/25 Task Critical Task Progress Milestone Summary Rolled Up Task Rolled Up Critical Task Rolled Up Milestone Rolled Up Progress Split External Tasks Project Summary Group By Summary Figure 3-8 In Situ Cap Schedule

11 Figure 3-10 Dredge/Cap Hybrid Schedule ID Task Name Duration 1 Complete Design & Permitting 0 days 2 Bidding and Contractor Selection 54 days 3 Mobilization and Site Preparation 22 days 4 Slip 7 CAD Construction 45 days 5 Stryker Bay Dredge (126,566 cy) 106 days 6 Stryker Bay Covering and Capping (58,238 cy) 18 days 7 Place Surcharge (74,447 cy) 23 days 8 Await Surcharge Settlement 280 days 9 Place Env. Media in Stryker Bay (125,707 cy) 39 days 10 Slip 6 Dredging (42,053 cy) 35 days 11 Slip 6 Capping (53,918 cy) 17 days 12 Slip 6 Env. Media (5,029 cy) 2 days 13 Slip 7 CAD Closure (51,418) 16 days 14 Slip 7 Capping (74,447 cy - surcharge material) 23 days 15 Slip 7 Capping (8,184 cy - non surcharge material) 3 days 16 Slip 7 Env. Medial (11,097 cy) 4 days 17 Armor Slip 6 and 7 (22,840 cy) 7 days 18 Armor Mouth of Stryker Bay (3,793) 2 days 19 Demobilization 0 days Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 3/15 9/13 Task Critical Task Progress Milestone Summary Rolled Up Task Rolled Up Critical Task Rolled Up Milestone Rolled Up Progress Split External Tasks Project Summary Group By Summary Figure 3-10 Hybrid Schedule

13 Figure 3-12 Dredge/Off-Site Disposal Schedule ID Task Name Duration 1 Complete Design & Permitting 0 days 2 Bidding and Contractor Selection 54 days 3 Mobilization 30 days 4 Construct Dewatering and Shipping Plant 30 days 5 Dredge Stryker Bay - (197,390 cy) 165 days 6 Dredge Slip 6 - (100,000 cy) 84 days 7 Dredge Slip 7 - (190,500 cy) 159 days 8 Environmental Media in Stryker Bay (188,905 cy) 59 days 9 Environmental Media in Slip 6 (23,706 cy) 8 days 10 Environmental Media in Slip 7 (52,324 cy) 17 days 11 Armor Mouth of Stryker Bay (3,793 cy) 2 days 12 Armor Slip 6 (24,800 cy) 20 days 13 Armor Slip 7 (39,000 cy) 13 days 14 Demobilization 0 days Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 3/15 7/10 Task Critical Task Progress Milestone Summary Rolled Up Task Rolled Up Critical Task Rolled Up Milestone Rolled Up Progress Split External Tasks Project Summary Group By Summary Figure 3-12 Off-Site Schedule

April Capping approximately 28 acres of contaminated sediments in Keene Creek Bay/Slip 7;

April Capping approximately 28 acres of contaminated sediments in Keene Creek Bay/Slip 7; April 2004 Introduction This Proposed Plan describes the Minnesota Pollution Control Agency s (MPCA) preferred cleanup alternative for the Sediment Operable Unit of the St. Louis River/Interlake/Duluth