Peninsula Harbour Thin Layer Capping Project Monitoring Results Kay Kim Environment and Climate Change Canada October 2016 Overview Hg and PCB footprint Design – Cap Thickness • Medium: 10 – 30 cm with average of 15 cm • Coarse: 12.5 – 37.5 cm with average of 20 cm • A thicker cap and heavier sand was used in areas of high energy 4 Engineering Design Sand Specification - Chemical •  Chemical properties of the sand to meet CCME’s Interim Freshwater Sediment Quality Guidelines except for Chromium and Copper •  Cr and Cu levels were revised to local background levels as these levels are naturally high in this area. (Cr <=50 ppm; Cu <=90 ppm) 5 Project Site I Town of Marathon Aggregate Site . Permit Number 6708 LaFarge Aggregate Site Permit Number 6725 0" LaFarge Aggregate Site Permit Number 6724 LaFarge Dock Performance Criteria 1.  Cap area coverage 2.  Cap thickness 3.  Sand gradation 4.  Sand chemistry 5.  Turbidity 6.  Water Chemistry – release of Hg and PCBs from contaminated sediment 7 Environmental Mitigation Measures •  Silt fence placed to prevent sand from entering water in the staging area •  Installed turbidity curtains to protect two near shore habitat areas as per DFO/MNR advice •  Turbidity curtain box attached to the capping barge (contractor) 8 Implementation – Testing Cell •  Objective of the testing cell is to try out different placement methods to meet performance criteria •  Test cell chosen to cover both medium and coarse sand area •  Duration: 1 week •  Thickness Verification: 16 cores 9 (ISO 100 100 Malnutr- unluu LIMT OF DESBNED CAP CELL H. . o_ r: i LIMT DP CAPPED AREA SCALE 1 1250 DGE 0F TRANSITION ZONE EDGE OF ZONE (FDR AREA 1 ONLY) UMT 0F GAP AREA OF THIN LAYER CAP MEDIUM SAND LMTOFCAP - AREA or THIN LAYER CAP SAND) 5397100 5001 CAPFING CELL No. AND 'anE or 5AM: [cEus wn'uau1' IDENTIPIDATIDN DRE wmuN WING AREA 1) Imrmm: 1 ml! I: a. 2 AREA 2: A Fa? IREIA AREA 2). _4 ?Ih TTFE CIF Sm: SAND: CME 9ND . Ohm?4 cm. M1 zu-z om? Cum?1 LOCATION OF CORE ?m 2 AM) . EDGE OF ZDNE zu?a 5M1 5001 20?) Ina?D cam-5 can 4 .3mL1 05m 3 05M1-2 5.397.0110 own-3 CAP CEL. (TYFJ Om"! Dun?2 "l 3 li ism?4 AREA 1 mm 14 I Lurr or CAP C'm?l NH) 10001 I own?? EA 01ml 1 .EM-4 OHM-5 0%1 .8M-b Guru?J 5.596.9D0 011 i 16"? 01942-1 mm)? mm 4 .WH mam-I 1" .17 Mom?a maul-1 13 mam?2 1700M 01541?21 I 18001 I 150?? emu-4 17001 I "nu?1 own-1 17002 AREA 2 I MEDIUM SAND CAP {mud mam?3 17I.I2 2 . msm?JL mam?1 5 own?2 5.399.500 180?)! \m mam-J, 02m 922,04 .2m_3 .?ml?ozam ?1 I Quiz?4 021M-2 ?uurr 0F TEST cm . ?1m5?21m ?22m EDBE or zaNE "c 21? 1 .Tc I UMIT or 2mm Tc_2m_5 OTc-zm-s 5.3 5,396,600 CIF EDGE OF TRANSITION 20M: Capping Operation Summary •  Capped 23 ha with medium/coarse sand •  Placed 36,000 tonnes of coarse; 50,000 tonnes of medium sand •  Average production 4,635 m2/day or 1,616 tonnes/day •  Started capping on June 5 and finished on Aug 5, 2012 •  3 hours of delay due to weather; 26 hours of delay due to 11 mechanical problems Post Implementation Monitoring Studies •  Tracer Study (ECCC) •  Submerged Aquatic Vegetation and Cap Movement (Rob Foster, Northern Bioscience) 12 Core Tracer Study ?LEGD. - .3. I k- 200 Meters 2007 bathymetry and sidescan sonar data acquired and processed by Inc. Cap material drawing extracted from Public Works and Government Services Canada Project R.024725.001. Drawing M-09. 1.Pe?msukiHaH 7 . . - . 840:10k110 your? 2012 Lnadew 32?. 5 ,1 Xradiographs of cores from quadrants at 10 and 12 depths20'm22 24 26 28 30 32 34 25Initial cesium concentration in sediment core profiles 0 -1 C ore in te rva l mi dp oi nt (cm) -2 -3 7m Eas t 7m Sout h 8m Nort h 8m West 10m Eas t 10m South 12m North 12m South -4 -5 -6 -7 -8 -9 -10 -200 0 20 0 40 0 6 00 8 00 1000 1200 Me asu re d [Cs] (mg /kg) 1400 1600 1800 2000 October 2012 cesium concentration in sediment core profiles 8 7m - Ref 7m -West 8 m- South 8m -East 10m - East 12m -South 12m - East C ore in te rva l mi dp oi nt (cm) 6 4 2 0 Cap Sediment I nt erface -2 -4 -6 0 500 1000 1500 Mea su red [C s] (mg /k g) 2500 July 2013 cesium concentration in sediment core profiles 14 12 12m - Wes t Centre 12m - North Inside 10m - North Out side 10m - North Inside 8m - East Ins ide 8m - East Outside 7m - North Outside 7m - North Centre C ore in te rva l mi dp oi nt (cm) 10 8 6 4 2 0 -2 -4 -6 -8 -10 0 500 1000 Me as ure d [Cs ] (mg /g) 1500 Core Tracer Study Conclusion •  Cs, the tracer did not move through the cap. •  Mercury will be bound to existing soft sediments below the cap. 22 Submerged Aquatic Vegetation (SAV) and Cap Movement (Northern Bioscience) Objectives: •  Assess the distribution and potential movement of the sand cap; and •  Assess the recovery of SAV within the cap and adjacent areas 23 Submerged Aquatic Vegetation (SAV) and Cap Movement (Northern Bioscience) •  Study conducted in 2012 right after capping operation to provide baseline conditions •  Study conducted in 2013 (year 1 post cap) •  20.4 km of transects at 50 m spacing between transects •  Over 5000 video images interpreted at 5 m intervals along transects •  34 ponar grabs to verify substrate composition 24 Survey Grid (50 spacing) Ponar Grab Stations 0 2013 Ponar Grabs 2012 Ponar Grabs Scan Submerged Aquatic Vegetation •  Stonewort (Chara) •  Pondweed (Potamogeton) •  Canada Waterweed (Elodea canadensis) 27 Cap Imagery (2012 post cap) 12/09/25? 03:21: Capping Materi al Cap Material from grab sampler Outside Cap 83$ 0.8 I no?w 3:338 258 0 38088 0 ?Ban 0 50:0 no again 088:. An 3 5829: SAV Study Conclusion •  Medium and coarse sand deposited in the cap area had remained in place. No evidence of cap movement. •  There is a thin layer of fine sediment on top of cap. •  Sparse patches of stonewort and other submerged aquatic vegetation in the capped area one year post‐ capping. •  Dense submergents along portions of the cap margin in shallow water. 34 Long Term Monitoring Studies (adaptive approach required) •  Re-colonization of submerged aquatic vegetation (0, 1, 3, 5, 10 yrs) •  Re-colonization of benthic community (5, 10, 15, 20) •  Benthic invertebrate tissue survey (Hg) (5, 10, 15, 20) •  Fish tissue survey (5, 10, 15, 20) •  Sediment Chemistry (5, 10, 15, 20) 35 Thank You •  PH Community Liaison Committee •  EcoSuperior Environmental Programs •  PH Sediment Remediation Technical Team •  PH Sediment Remediation Management Committee 36 Need more information? •  Please contact: •  Kay Kim @ 416-739-4787 •  Email: kay.kim@canada.ca 37