Document Puyallup_doc_c461a90c3f

APPENDIX G OREGON LNG SOILS, WETLANDS, AND WATERBODY INFORMATION Appendix G1: Wetlands and Waterbodies Crossed by the Oregon LNG Pipeline Appendix G2: Landslide Hazard Areas Crossed by the Oregon LNG Pipeline Appendix G3: Site-specific Waterbody Crossing Plans Appendix G4: Stream Channel Assessment and Scour Analysis Appendix G5: Riparian Areas Crossed by the Oregon LNG Pipeline Appendix G6: Landslide and Debris Flow Risk Near Waterbody Crossings ---PAGE BREAK--- ---PAGE BREAK--- APPENDIX G1 WETLANDS AND WATERBODIES CROSSED BY THE OREGON LNG PIPELINE ---PAGE BREAK--- ---PAGE BREAK--- Facility Type Wetland ID Cowardin Classification a HGM b Offsite Mapping c Permanent Wetland Impact d (acres) Temporary Wetland Impact e (acres) Total Construction Disturbance (acres) Terminal W4BCL01 PSS Depressional N 2.962 0.129 3.091 W4BCL02 PSS Depressional N 0.076 0.000 0.076 W4BCL03 PSS Depressional N 0.135 0.000 0.135 W4BCL04 PSS Depressional N 0.313 0.000 0.313 W4BCL05 E2EM Estuarine Fringe N 26.748 0.827 27.575 W4BCL06 E2EM Estuarine Fringe N 0.012 0.006 0.018 W4BCL07 E2EM Estuarine Fringe N 0.489 0.121 0.610 W4BCL08 E2EM Estuarine Fringe N 0.293 0.017 0.310 W4BCL09 E2EM Depressional N 0.028 0.000 0.028 W4BCL11 E2EM Estuarine Fringe N 0.015 0.035 0.050 W4BCL12 E2EM Estuarine Fringe N 0.023 0.000 0.023 W5BCL016 E2EM Estuarine Fringe N 0.461 0.307 0.768 W5BCL020 PEM Depressional N 0.178 0.000 0.178 W5BCL048 PEM Depressional N 0.330 0.001 0.331 W5BCL049A PSS Depressional N 0.694 0.008 0.702 W5BCL059 PEM Estuarine Fringe N 0.010 0.012 0.022 Terminal Subtotal 32.767 1.463 34.230 Access Road W5BCL020 PEM Depressional N 0.012 0.042 0.054 W5BCL021 PEM Depressional N 0.397 0.199 0.596 W5BCL023 PEM Depressional N 0.507 0.382 0.889 W5BCL084 PFO Depressional N 0.001 0.000 0.001 W5BCL085 PFO Depressional N 0.160 0.000 0.160 W5BCL086 PSS Depressional N 0.028 0.013 0.041 Access Road Subtotal 1.105 0.636 1.741 Terminal Total 33.872 2.099 35.971 Nonjursidictional Facilities Effluent & Potable Water Lines W5BCL019 PEM Depressional N 0.000 0.299 0.299 W5BCL023 PEM Depressional N 0.000 0.033 0.033 Potable Water Line W99CL0002 PFO/SS TBD Y 0.040 0.000 0.040 W99CL0003 PEM/SS TBD Y 0.000 0.029 0.029 W99CL0004 PSS TBD Y 0.000 0.014 0.014 W99CL0005 PEM TBD Y 0.000 0.187 0.187 W99CL0007 PFO TBD Y 0.002 0.000 0.002 Effluent and Potable Water Line Subtotal 0.042 0.23 0.272 HDD Drill Area W99CL0005 PEM TBD Y 0.000 0.013 0.013 W99CL0006 PFO TBD Y 0.104 0.000 0.104 W99CL0007 PFO TBD Y 0.892 0.000 0.892 W99CL0008 PEM TBD Y 0.000 0.026 0.026 HDD Pullback W5BCL019 PEM Depressional N 0.000 0.049 0.049 W5BCL020 PEM Depressional N 0.000 0.296 0.296 W5BCL021 PEM Depressional N 0.000 0.037 0.037 W5BCL023 PEM Depressional N 0.000 0.079 0.079 HDD Drill Area and Pullback Subtotal 0.996 0.500 1.496 Nonjursidictional Facilities Total 1.038 0.730 1.768 a Cowardin Classification System: PEM = palustrine emergent; PSS = palustrine scrub-shrub; PFO = palustrine forested, E2EM=estuarine emergent. b Wetland classes based on Hydrogeomorphic Assessment Guidebook for Tidal Wetlands of the Oregon Coast, TBD = to be determined due to lack of site access. c Y = Oregon LNG surveyed wetland, N = no site access – proxy data used. e Permanent impacts on wetlands requiring long term restoration including the functional conversion of forested wetlands to scrub-shrub wetlands, or conversation of scru shrub wetlands to emergent wetlands. f Temporary impacts on wetlands that are expected to recover to preconstruction conditions. Table G1-1 Wetlands Impacted by Terminal and Associated Facilities G1‐1 ---PAGE BREAK--- MP Wetland ID Cowardian Classification a HGM b County/State Tax Lot Offsite Mapping c Length of pipeline (feet) d Permanent Wetland Impact (acres) e Temporary Wetland Impact (acres) f Total Construction Disturbance (acres) Excavated Volume g (cubic yards) Fill Volume (cubic yards) 0.1 W5BCL050 PSS Depressional CLATSOP, OR 08N10W15D001600 N 141 0.1 0.2 0.2 417.6 417.6 0.1 W5BCL058 PEM Depressional CLATSOP, OR 08N10W15D001600 N 327 0.0 0.7 0.7 969.9 969.9 0.2 W5BCL021 PEM Depressional CLATSOP, OR 08N10W22AC01000 N 310 0.0 1.5 1.5 917.2 917.2 0.2 W5BCL052 PEM Depressional-Fringe CLATSOP, OR 08N10W15D001600 N 504 0.0 1.1 1.1 1492 1492 0.8 W99CL0021 E2USN Estuarine CLATSOP, OR 08N10W23BD00600 Y 1774 0.0 5.1 5.1 5256 5256 0.8 W99CL0021A PEM TBD CLATSOP, OR 08N10W23BD00600 Y 960 0.0 3.4 3.4 2843.8 2843.8 1.3 W5BCL015A AW TBD CLATSOP, OR 08N10W230000200 N 718 0.0 1.2 1.2 2126.3 2126.3 1.3 W5BCL015K PSS Depressional CLATSOP, OR 08N10W230000200 N 21 0.0 0.0 0.0 61.2 61.2 1.4 W5BCL015L PSS Depressional CLATSOP, OR 08N10W230000200 N 258 0.2 0.3 0.4 764.9 764.9 1.4 W5BCL015N PSS Depressional CLATSOP, OR 08N10W230000200 N 103 0.1 0.1 0.2 304.8 304.8 1.5 W5BCL015Q PSS Depressional CLATSOP, OR 08N10W230000200 N 110 0.1 0.1 0.2 326.2 326.2 1.5 W5BCL015R PSS Depressional CLATSOP, OR 08N10W260000500 N 44 0.0 0.1 0.2 130.5 130.5 1.6 W5BCL015O AW TBD CLATSOP, OR 08N10W260000500 N 933 0.0 3.0 3.0 2765.2 2765.2 1.7 W5BCL060 AW Depressional CLATSOP, OR 08N10W260000500 N 486 0.0 1.6 1.6 1439.8 1439.8 1.8 W5BCL061 PSS Depressional CLATSOP, OR 08N10W260000500 N 255 0.2 0.4 0.6 756.8 756.8 1.8 W99CL200 PSS TBD CLATSOP, OR 08N10W260000401 Y 115 0.2 0.3 0.4 340.5 340.5 2.0 W5BCL062 AW Depressional CLATSOP, OR 08N10W260000500 N 0 0.0 0.0 0.0 0 0 2.0 W99CL201 PFO TBD CLATSOP, OR 08N10W260000800 Y 937 2.2 0.0 2.2 2776.1 2776.1 2.3 W99CL202 PSS TBD CLATSOP, OR 08N10W250000500 Y 235 0.2 0.6 0.7 697.2 697.2 2.4 W38CL083 PEM TBD CLATSOP, OR 08N10W250000500 Y 0 0.0 0.0 0.0 0 0 2.4 W5BCL066 PEM Depressional CLATSOP, OR 08N10W250000400 N 239 0.0 1.1 1.1 709.3 709.3 2.5 W5BCL067 PSS Depressional CLATSOP, OR 08N10W250000400 N 513 0.4 0.6 1.0 1519.3 1519.3 2.7 W40CL001 PSS TBD CLATSOP, OR 08N10W250000400 Y 1464 1.0 2.6 3.6 4337.9 4337.9 3.3 W40CL010 AW TBD CLATSOP, OR 08N10W250001500 Y 327 0.0 1.9 1.9 968.4 968.4 3.4 W40CL011 AW TBD CLATSOP, OR 08N10W250001500 Y 175 0.0 0.3 0.3 517.3 517.3 3.4 W99CL026 AW TBD CLATSOP, OR 08N10W250001500 Y 161 0.0 0.3 0.3 478 478 3.5 W99CL077B AW TBD CLATSOP, OR 08N10W250001500 Y 143 0.0 0.3 0.3 424.7 424.7 3.6 W99CL030 PEM TBD CLATSOP, OR 08N10W360000200 Y 72 0.0 0.1 0.1 211.9 211.9 3.7 W99CL033 PFO TBD CLATSOP, OR 08N10W360000300 Y 365 0.5 0.0 0.5 1080.6 1080.6 3.7 W99CL077A AW TBD CLATSOP, OR 08N10W360000200 Y 1249 0.0 3.3 3.3 3702 3702 3.8 W99CL017 AW TBD CLATSOP, OR 08N10W360000300 Y 492 0.0 1.1 1.1 1457.6 1457.6 3.8 W99CL076 AW TBD CLATSOP, OR 08N10W360000300 Y 154 0.0 0.4 0.4 457.2 457.2 4.2 W5BCL042F AW TBD CLATSOP, OR 08N10W360001800 N 1800 0.0 5.4 5.4 5333.7 5333.7 4.5 W42CL001 PEM TBD CLATSOP, OR 08N10W360001800 Y 1423 0.0 5.1 5.1 4216.5 4216.5 4.5 W5BCL042A AW TBD CLATSOP, OR 07N10W010000200 N 0 0.0 0.0 0.0 0 0 4.5 W5BCL073 PFO TBD CLATSOP, OR 08N10W360001706 N 0 0.0 0.0 0.0 0 0 4.6 W5BCL042C AW TBD CLATSOP, OR 07N10W000000100 WATER N 561 0.0 1.8 1.8 1663.3 1663.3 4.6 W5BCL043 PEM Depressional CLATSOP, OR 07N10W010000200 N 400 0.0 1.0 1.0 1186.6 1186.6 Lower Columbia HUC 4 Subbasin - Clatsop County, Oregon Table G1-2 Wetlands Crossed by the Oregon LNG Pipeline G1‐2 ---PAGE BREAK--- MP Wetland ID Cowardian Classification a HGM b County/State Tax Lot Offsite Mapping c Length of pipeline (feet) d Permanent Wetland Impact (acres) e Temporary Wetland Impact (acres) f Total Construction Disturbance (acres) Excavated Volume g (cubic yards) Fill Volume (cubic yards) Table G1-2 Wetlands Crossed by the Oregon LNG Pipeline 4.7 W42CL002 AW TBD CLATSOP, OR 07N10W010000500 Y 656 0.0 1.7 1.7 1943.7 1943.7 4.8 W5BCL044 PEM Depressional CLATSOP, OR 07N10W010001003 N 7 0.0 0.0 0.0 20.1 20.1 4.9 W5BCL042D AW TBD CLATSOP, OR 07N10W010001003 N 147 0.0 0.4 0.4 435 435 5.0 W40CL016 AW TBD CLATSOP, OR 07N10W010001003 Y 689 0.0 1.6 1.6 2041.4 2041.4 5.0 W40CL018 PFO TBD CLATSOP, OR 07N10W010001003 Y 0 0.1 0.0 0.1 0 0 5.1 W39CL004 AW TBD CLATSOP, OR 07N10W010001003 Y 100 0.0 1.0 1.0 296.2 296.2 5.5 W40CL023 AW TBD CLATSOP, OR 07N09W060001500 Y 241 0.0 4.0 4.0 714.4 714.4 5.5 W99CL074 AW TBD CLATSOP, OR 07N09W060001500 Y 289 0.0 1.1 1.1 855.5 855.5 5.6 W99CL073 AW TBD CLATSOP, OR 07N09W060001500 Y 301 0.0 1.4 1.4 890.8 890.8 6.2 W5BCL047 PEM Depressional CLATSOP, OR 07N10W120000500 N 67 0.0 0.1 0.1 199 199 6.3 W38CL007B PEM TBD CLATSOP, OR 07N10W120003000 Y 312 0.0 0.9 0.9 924.9 924.9 7.9 W1BCL001 PFO Slope CLATSOP, OR 07N10W130000801 N 222 0.4 0.0 0.4 657 657 8.0 W1BCL002 PEM Riverine CLATSOP, OR 07N10W240000100 N 146 0.0 0.2 0.2 431.3 431.3 8.0 W1BCL003 PEM Slope CLATSOP, OR 07N10W240000100 N 0 0.0 0.0 0.0 0 0 8.1 W1BCL005 PEM Slope CLATSOP, OR 07N10W240000100 N 0 0.0 0.0 0.0 0 0 8.8 W1BCL008 PEM Riverine CLATSOP, OR 07N10W240000100 N 111 0.0 0.2 0.2 327.6 327.6 10.2 W1BCL011 PEM Slope CLATSOP, OR 07N10W360000100 N 135 0.0 0.2 0.2 400.9 400.9 10.2 W1BCL023 PEM Flats CLATSOP, OR 07N10W360000100 N 150 0.0 0.2 0.2 443.5 443.5 10.3 W1BCL022 PSS Flats CLATSOP, OR 07N10W360000100 N 60 0.0 0.1 0.1 178.4 178.4 10.9 W39CL006 PEM TBD CLATSOP, OR 07N09W310000400 Y 10 0.0 0.0 0.0 29.5 29.5 10.9 W99CL004 PEM TBD CLATSOP, OR 07N09W310000400 Y 143 0.0 0.7 0.7 424.1 424.1 10.9 W99CL007 PEM TBD CLATSOP, OR 07N09W310000500 Y 279 0.0 0.9 0.9 825.4 825.4 12.3 W1BCL032 PEM Flats CLATSOP, OR 06N09W000000600 N 123 0.0 0.2 0.2 365.5 365.5 12.3 W1BCL033 PEM Flats CLATSOP, OR 07N09W000000300 N 141 0.0 0.2 0.2 416.8 416.8 12.4 W1BCL030 PEM Flats CLATSOP, OR 06N09W000000600 N 59 0.0 0.1 0.1 173.6 173.6 12.4 W1BCL031 PEM Flats CLATSOP, OR 06N09W000000600 N 0 0.0 0.0 0.0 0 0 12.5 W1BCL025 PEM Riverine CLATSOP, OR 06N09W000000600 N 40 0.0 0.0 0.0 119 119 12.5 W1BCL028 PEM Slope CLATSOP, OR 06N09W000000600 N 0 0.0 0.0 0.0 0 0 12.5 W1BCL029 PEM Flats CLATSOP, OR 06N09W000000600 N 0 0.0 0.1 0.1 0 0 13.1 W1BCL035 PSS Slope CLATSOP, OR 06N09W000000600 N 102 0.1 0.1 0.1 303.5 303.5 13.1 W1BCL037 PEM Slope CLATSOP, OR 06N09W000000600 N 0 0.0 0.0 0.0 0 0 13.2 W1BCL036 PSS Slope CLATSOP, OR 06N09W000000600 N 244 0.2 0.3 0.4 724.1 724.1 15.1 W5BCL080 PEM Depressional CLATSOP, OR 06N09W000000600 N 17 0.0 0.0 0.0 51.5 51.5 15.8 W5BCL005 PEM Depressional CLATSOP, OR 06N09W360000100 N 2 0.0 0.0 0.0 4.7 4.7 15.9 W5BCL006 PEM Depressional CLATSOP, OR 06N09W360000100 N 0 0.0 0.0 0.0 0 0 15.9 W5BCL007 PEM Depressional CLATSOP, OR 06N09W000000000 N 162 0.0 0.3 0.3 479.6 479.6 15.9 W5BCL008 PEM Depressional CLATSOP, OR 06N09W000000000 N 47 0.0 0.1 0.1 138 138 15.9 W5BCL009 PEM Depressional CLATSOP, OR 06N09W360000100 N 0 0.0 0.0 0.0 0 0 16.0 W5BCL010 PEM Depressional CLATSOP, OR 06N09W360000100 N 6 0.0 0.0 0.0 16.6 16.6 16.0 W5BCL011 PEM Depressional CLATSOP, OR 06N09W000000000 N 66 0.0 0.1 0.1 194.6 194.6 G1‐3 ---PAGE BREAK--- MP Wetland ID Cowardian Classification a HGM b County/State Tax Lot Offsite Mapping c Length of pipeline (feet) d Permanent Wetland Impact (acres) e Temporary Wetland Impact (acres) f Total Construction Disturbance (acres) Excavated Volume g (cubic yards) Fill Volume (cubic yards) Table G1-2 Wetlands Crossed by the Oregon LNG Pipeline 16.6 W5BCL012B PEM TBD CLATSOP, OR 06N09W360000100 N 0 0.0 0.0 0.0 0 0 17.8 W5BCL070 PEM Riverine CLATSOP, OR 06N09W360000100 N 63 0.0 0.1 0.1 186.1 186.1 17.8 W5BCL071 PEM Depressional CLATSOP, OR 06N09W360000100 N 0 0.0 0.0 0.0 0 0 18.3 W5BCL069 PSS Depressional CLATSOP, OR 06N08W000001800 N 0 0.0 0.0 0.0 0 0 18.4 W5BCL068 PEM Riverine CLATSOP, OR 06N08W000001800 N 0 0.0 0.0 0.0 0 0 18.6 W1BCL012 PFO Riverine CLATSOP, OR 06N08W000001800 N 71 0.1 0.0 0.1 211.8 211.8 18.6 W1BCL014 PFO Flats CLATSOP, OR 06N08W000001800 N 193 0.3 0.0 0.3 573.3 573.3 18.9 W1BCL015 PFO Slope CLATSOP, OR 06N08W000003400 N 19 0.0 0.0 0.0 55.4 55.4 19.0 W1BCL016 PFO Slope CLATSOP, OR 06N08W000003400 N 0 0.0 0.0 0.0 0 0 19.0 W1BCL018 PFO Slope CLATSOP, OR 06N08W000003700 N 0 0.0 0.0 0.0 0 0 19.0 W1BCL019 PEM Slope CLATSOP, OR 06N08W000003700 Y 0 0.0 0.0 0.0 0 0 19.3 W1BCL020 PEM Riverine CLATSOP, OR 06N08W000003400 N 97 0.0 0.1 0.1 288.6 288.6 19.3 W1BCL021 PFO Slope CLATSOP, OR 06N08W000003300 N 0 0.0 0.0 0.0 0 0 19.4 W7BCL004 PEM Slope CLATSOP, OR 06N08W000003400 N 9 0.0 0.0 0.0 27.2 27.2 19.6 W2BCL008 PFO Riverine CLATSOP, OR 06N08W000003400 N 245 0.4 0.0 0.4 727.4 727.4 19.7 W2BCL009 PEM Slope CLATSOP, OR 06N08W000003300 N 174 0.0 0.3 0.3 516.6 516.6 19.8 W2BCL007 PEM Slope CLATSOP, OR 06N08W160002000 N 0 0.0 0.0 0.0 0 0 22.1 W5BCL028 PEM Riverine CLATSOP, OR 06N08W160002000 N 67 0.0 0.1 0.1 199.5 199.5 22.4 W7BCL006 PFO Slope CLATSOP, OR 06N08W160002000 N 40 0.1 0.0 0.1 117.6 117.6 22.5 W6BCL003 PFO Riverine CLATSOP, OR 06N08W160002000 N 63 0.1 0.0 0.1 185.7 185.7 22.6 W6BCL002 PEM Riverine CLATSOP, OR 06N08W160002000 N 41 0.0 0.1 0.1 122 122 24.4 W5BCL001 PEM Slope CLATSOP, OR 06N08W260004100 N 25 0.0 0.0 0.0 75 75 24.8 W2BCL001 PSS Depressional CLATSOP, OR 06N08W260004100 N 60 0.0 0.1 0.1 176.7 176.7 24.9 W2BCL002 PEM Slope CLATSOP, OR 06N08W260004100 N 46 0.0 0.1 0.1 137.6 137.6 25.3 W2BCL003A PEM Riverine CLATSOP, OR 06N08W260004100 N 10 0.0 0.0 0.0 28.2 28.2 25.3 W2BCL004A PEM Riverine CLATSOP, OR 06N08W260004100 N 0 0.0 0.0 0.0 0 0 25.9 W2BCL006 PEM Riverine CLATSOP, OR 06N08W260004100 N 24 0.0 0.0 0.0 71.7 71.7 26.8 W5BCL003 PEM Slope CLATSOP, OR 05N08W010000100 N 0 0.0 0.0 0.0 0 0 27.3 W5BCL002 PEM Slope CLATSOP, OR 05N08W010000100 N 0 0.0 0.0 0.0 0 0 27.3 W5BCL078 PEM Depressional CLATSOP, OR 05N08W010000100 N 10 0.0 0.0 0.0 31 31 30.1 W6BCL001 PEM Depressional CLATSOP, OR 05N07W000000500 N 30 0.0 0.1 0.1 89.9 89.9 30.5 W1BCL039 PEM Flats CLATSOP, OR 05N07W000000500 N 41 0.0 0.0 0.0 120.4 120.4 30.7 W2BCL019 PEM Depressional CLATSOP, OR 05N07W000000500 N 0 0.0 0.0 0.0 0 0 31.3 W2BCL018 PEM Slope CLATSOP, OR 05N07W000000500 N 38 0.0 0.1 0.1 111.9 111.9 31.4 W2BCL017 PEM Riverine CLATSOP, OR 05N07W000000500 N 38 0.0 0.0 0.0 112.2 112.2 32.5 W3BCL001 PEM Slope CLATSOP, OR 05N07W000002500 N 42 0.0 0.1 0.1 124.5 124.5 33.8 W99CL102 PSS TBD CLATSOP, OR 05N07W330000300 Y 132 0.1 0.1 0.2 392.4 392.4 33.9 W39CL013 AW TBD CLATSOP, OR 05N07W330000300 Y 0 0.0 0.2 0.2 0 0 33.9 W39CL014 AW TBD CLATSOP, OR 05N07W330000300 Y 139 0.0 0.6 0.6 412.3 412.3 Nehalem HUC 4 Subasin - Clatsop County, OR G1‐4 ---PAGE BREAK--- MP Wetland ID Cowardian Classification a HGM b County/State Tax Lot Offsite Mapping c Length of pipeline (feet) d Permanent Wetland Impact (acres) e Temporary Wetland Impact (acres) f Total Construction Disturbance (acres) Excavated Volume g (cubic yards) Fill Volume (cubic yards) Table G1-2 Wetlands Crossed by the Oregon LNG Pipeline 34.0 W39CL015 AW TBD CLATSOP, OR 05N07W330000300 Y 406 0.0 1.1 1.1 1201.7 1201.7 34.1 W99CL002 AW TBD CLATSOP, OR 05N07W330000300 Y 387 0.0 0.8 0.8 1146.3 1146.3 34.4 W5BCL026 PEM Riverine CLATSOP, OR 05N07W330000700 N 0 0.0 0.0 0.0 0 0 36.3 W3BCL101 PSS/PFO TBD CLATSOP, OR 04N07W000000400 N 458 1.0 0.0 1.0 1358.1 1358.1 36.5 W3BCL100 PSS/PFO TBD CLATSOP, OR 04N07W000000300 N 92 0.1 0.0 0.1 271.5 271.5 36.7 W3BCL101b PSS/PFO TBD CLATSOP, OR 04N07W000000400 N 2169 5.3 0.0 5.3 6426.7 6426.7 37.1 W3BCL003 PFO Slope CLATSOP, OR 04N07W000000102 N 29 0.1 0.0 0.1 84.7 84.7 37.2 W3BCL002 PFO Slope CLATSOP, OR 04N07W000000102 N 38 0.1 0.0 0.1 113.9 113.9 37.6 W8BCL004 PEM Slope CLATSOP, OR 04N07W000000100 N 803 0.0 1.4 1.4 2379.1 2379.1 38.3 W8BCL003 PSS Depressional CLATSOP, OR 04N07W000000100 N 42 0.0 0.0 0.1 125.3 125.3 38.4 W8BCL002 PSS Depressional CLATSOP, OR 04N07W000000100 N 43 0.0 0.0 0.0 128.8 128.8 38.5 W8BCL001 PSS Depressional CLATSOP, OR 04N07W000000100 N 50 0.0 0.0 0.1 146.8 146.8 39.1 W2BCL030B PEM Riverine CLATSOP, OR 04N07W130000304 N 16 0.0 0.0 0.0 46.3 46.3 39.3 W2BCL028 PEM Riverine CLATSOP, OR 04N07W130000304 N 124 0.0 0.2 0.2 368.3 368.3 39.5 W2BCL026 PEM Slope CLATSOP, OR 04N07W130000304 N 128 0.0 0.2 0.2 379.3 379.3 39.6 W1BCL050A PFO Slope CLATSOP, OR 04N07W000002500 N 462 0.8 0.0 0.8 1368.5 1368.5 40.6 W8BCL030 PEM TBD CLATSOP, OR ROW N 153 0.0 0.2 0.2 452.8 452.8 40.9 W8BCL007C PSS TBD CLATSOP, OR 04N06W000001000 N 101 0.1 0.1 0.2 298.7 298.7 41.4 W8BCL011A PFO TBD CLATSOP, OR 04N06W000000607 N 0 0.0 0.0 0.0 0 0 41.5 W8BCL011B PFO TBD CLATSOP, OR 04N06W000000607 N 108 0.2 0.0 0.2 319.2 319.2 41.6 W8BCL012 PFO Depressional CLATSOP, OR 04N06W000000607 N 87 0.2 0.0 0.2 257.4 257.4 41.7 W8BCL013 PFO Depressional CLATSOP, OR 04N06W000000607 N 80 0.1 0.0 0.1 236.8 236.8 41.9 W8BCL014 PSS Depressional CLATSOP, OR 04N06W000000603 N 152 0.1 0.2 0.3 449.1 449.1 42.0 W8BCL015 PSS Depressional CLATSOP, OR 04N06W000000603 N 86 0.1 0.1 0.1 254.7 254.7 42.2 W8BCL017 PSS Depressional CLATSOP, OR 04N06W000000603 N 133 0.1 0.0 0.1 393.3 393.3 42.3 W8BCL018 PFO Riverine CLATSOP, OR 04N06W000000603 N 292 0.5 0.0 0.5 865.2 865.2 42.6 W1BCL040 PEM Riverine CLATSOP, OR 04N06W000000603 N 0 0.0 0.0 0.0 0 0 43.0 W1BCL042 PEM Slope CLATSOP, OR 04N06W000000603 N 0 0.0 0.0 0.0 0 0 43.7 W1BCL045 PEM Riverine CLATSOP, OR 04N06W000000600 N 0 0.0 0.0 0.0 0 0 43.9 W1BCL046 PEM Riverine CLATSOP, OR 04N06W000000600 N 63 0.0 0.1 0.1 187.2 187.2 44.0 W1BCL047 PEM Riverine CLATSOP, OR ROW N 0 0.0 0.0 0.0 0 0 44.2 W1BTI001 PFO Riverine TILLAMOOK, OR 03N06W000099980 N 69 0.1 0.0 0.1 203.3 203.3 44.3 W1BTI002 PEM Riverine TILLAMOOK, OR 03N06W000099980 N 0 0.0 0.0 0.0 0 0 44.8 W5BTI003 PEM Riverine TILLAMOOK, OR 03N06W000004600 N 0 0.0 0.0 0.0 0 0 45.5 W1BTI004 PEM Slope TILLAMOOK, OR 03N06W000000800 N 58 0.0 0.1 0.1 172.9 172.9 47.4 W5BTI001 PEM Depressional TILLAMOOK, OR 03N06W000000100 N 49 0.0 0.1 0.1 146.5 146.5 47.6 W6BCO004 PFO Riverine COLUMBIA, OR 04N05W000004000 N 31 0.1 0.0 0.1 92 92 48.3 W1BCO001 PEM Depressional COLUMBIA, OR 04N05W000003900 N 0 0.0 0.0 0.0 0 0 48.3 W1BCO002 PSS Depressional COLUMBIA, OR 04N05W000003900 N 0 0.0 0.0 0.0 0.018 0 Nehalem HUC 4 Subasin - Tillamook County, OR G1‐5 ---PAGE BREAK--- MP Wetland ID Cowardian Classification a HGM b County/State Tax Lot Offsite Mapping c Length of pipeline (feet) d Permanent Wetland Impact (acres) e Temporary Wetland Impact (acres) f Total Construction Disturbance (acres) Excavated Volume g (cubic yards) Fill Volume (cubic yards) Table G1-2 Wetlands Crossed by the Oregon LNG Pipeline 49.4 W4BCO001 PEM Depressional COLUMBIA, OR 04N05W000003600 N 18 0.0 0.0 0.0 53.1 53.1 50.6 W3BCO111 PFO Slope COLUMBIA, OR 04N05W000003600 N 115 0.1 0.0 0.1 341 341 50.7 W3BCO113 PEM Slope COLUMBIA, OR 04N05W000003400 N 0 0.0 0.0 0.0 0 0 50.8 W3BCO112 PFO Slope COLUMBIA, OR 04N05W000003400 N 89 0.1 0.0 0.1 264.2 264.2 53.6 W3BCO002 PSS Riverine COLUMBIA, OR 04N05W000001800 N 1 0.0 0.0 0.0 2.8 2.8 55.1 W4BCO002 PEM Depressional COLUMBIA, OR 04N05W000002100 N 0 0.0 0.0 0.0 0 0 55.4 W3BCO109 PEM Riverine COLUMBIA, OR 04N05W000000200 N 0 0.0 0.0 0.0 0 0 55.5 W3BCO110 PEM Depressional COLUMBIA, OR 04N05W000000200 N 0 0.0 0.0 0.0 0 0 55.8 W3BCO107 PEM Depressional COLUMBIA, OR 04N05W000000200 N 553 0.0 1.0 1.0 1639.8 1639.8 57.7 W3BCO100 PFO TBD COLUMBIA, OR 05N05W000007800 N 0 0.0 0.0 0.0 0 0 63.5 W3BCO102 PFO Slope COLUMBIA, OR 05N04W230000600 N 149 0.2 0.0 0.2 440.7 440.7 63.6 W3BCO103 PEM Riverine COLUMBIA, OR 05N04W230000600 N 0 0.0 0.1 0.1 0 0 63.6 W3BCO103c PEM Riverine COLUMBIA, OR 05N04W230000600 N 174 0.0 0.5 0.5 515.5 515.5 66.3 W3BCO101 PEM Slope COLUMBIA, OR 05N03W190000100 N 110 0.0 0.2 0.2 326.1 326.1 69.1 W6BCO005 PFO Riverine COLUMBIA, OR 05N03W220000200 N 112 0.3 0.0 0.3 330.6 330.6 70.2 W3BCO003 PEM Riverine COLUMBIA, OR 05N03W140000100 N 0 0.0 0.0 0.0 0 0 71.0 W1BCO020 PEM Depressional COLUMBIA, OR 05N03W140000100 N 0 0.0 0.0 0.0 0 0 71.1 W1BCO021 PEM Slope COLUMBIA, OR 05N03W130000100 N 0 0.0 0.0 0.0 0 0 71.2 W1BCO022 PEM Depressional COLUMBIA, OR 05N03W130000100 N 0 0.0 0.0 0.0 0 0 72.9 W3BCO007 PFO Depressional COLUMBIA, OR 05N02W180000100 N 77 0.3 0.0 0.3 227.7 227.7 73.5 W1BCO023 PFO Riverine COLUMBIA, OR 05N02W170000200 N 72 0.1 0.0 0.1 213.6 213.6 73.6 W1BCO024 PSS Depressional COLUMBIA, OR 05N02W170000200 N 106 0.1 0.1 0.2 312.8 312.8 74.6 W6BCO002 PFO Riverine COLUMBIA, OR 05N02W160000200 N 365 0.7 0.0 0.7 1081 1081 74.9 W6BCO001 PFO Riverine COLUMBIA, OR 05N02W160000200 N 21 0.0 0.0 0.0 63.6 63.6 Lower Columbia Clastskanie HUC 4 Subasin - Columbia County, OR 76.4 W3BCO013 PEM/PFO Riverine COLUMBIA, OR 05N02W150000100 N 92 0.1 0.0 0.1 273.7 273.7 78.4 W3BCO121 PSS Riverine COLUMBIA, OR 05N02W130000100 N 13 0.0 0.0 0.0 37.1 37.1 78.7 W3BCO120 PSS Slope COLUMBIA, OR 05N02W130000100 N 137 0.1 0.1 0.2 405.3 405.3 78.9 W3BCO119 PSS Slope COLUMBIA, OR 05N02W130000100 N 94 0.2 0.0 0.2 277.8 277.8 79.0 W3BCO118 PSS Slope COLUMBIA, OR 05N01W180000500 N 199 0.0 0.3 0.3 588.3 588.3 79.1 W3BCO116 PSS Slope COLUMBIA, OR 05N01W180000500 N 0 0.0 0.0 0.0 0.011 0 79.1 W3BCO117 PFO Slope COLUMBIA, OR 05N01W180000500 N 198 0.3 0.0 0.3 588.1 588.1 79.2 W3BCO115 PSS Slope COLUMBIA, OR 05N01W180000500 N 212 0.1 0.1 0.2 627.9 627.9 79.8 W3BCO114A PSS Riverine COLUMBIA, OR 05N01W180000300 N 0 0.0 0.0 0.0 0 0 79.8 W3BCO114B PSS Riverine COLUMBIA, OR 05N01W180000300 N 60 0.0 0.1 0.1 177.9 177.9 80.2 W5BCO012 PEM Slope COLUMBIA, OR 05N01W170000300 N 0 0.0 0.3 0.3 0 0 80.2 W99CO001 PEM TBD COLUMBIA, OR 05N01W170000204 Y 126 0.0 0.2 0.2 373.3 373.3 81.4 W5BCO013 PFO Riverine COLUMBIA, OR 05N01W160000100 N 306 0.8 0.0 0.8 907.6 907.6 Lower Willamette HUC 4 Subbasin - Columbia County, OR Lower Columbia Clastskanie HUC 4 Subasin - Columbia County, OR G1‐6 ---PAGE BREAK--- MP Wetland ID Cowardian Classification a HGM b County/State Tax Lot Offsite Mapping c Length of pipeline (feet) d Permanent Wetland Impact (acres) e Temporary Wetland Impact (acres) f Total Construction Disturbance (acres) Excavated Volume g (cubic yards) Fill Volume (cubic yards) Table G1-2 Wetlands Crossed by the Oregon LNG Pipeline 81.5 W99CO030 PFOA TBD COLUMBIA, OR 05N01W170000200 Y 174 0.6 0.0 0.6 515.9 515.9 81.6 W99CO030 PFO/SSA TBD COLUMBIA, OR 05N01W160000100 Y 132 0.7 0.0 0.7 391.4 391.4 81.6 W99CO031 PEM TBD COLUMBIA, OR 05N01W160000100 Y 475 0.0 1.9 1.9 1407.4 1407.4 81.7 W3BCO009 PSS Riverine COLUMBIA, OR 05N01W160000201 N 173 0.1 0.1 0.2 511.4 511.4 81.7 W99CO005 PFOA TBD COLUMBIA, OR 05N01W160000100 Y 98 0.5 0.0 0.5 291.7 291.7 81.7 W99CO006 PFO TBD COLUMBIA, OR 05N01W160000100 Y 85 1.2 0.0 1.2 251 251 81.7 W99CO007 PFOC TBD COLUMBIA, OR 05N01W160000100 Y 0 0.1 0.0 0.1 0 0 81.7 W99CO032 PEM TBD COLUMBIA, OR 05N01W160000201 Y 77 0.0 0.3 0.3 228.6 228.6 82.0 W3BCO008 PEM Riverine COLUMBIA, OR 05N01W1600 WATER N 0 0.0 0.0 0.0 0 0 82.7 W99CW001 PEM TBD COWLITZ, WA WB1502002 Y 353 0.0 1.6 1.6 1047.1 1047.1 83.0 W99CW002 PEM TBD COWLITZ, WA WB1502001 Y 3024 0.0 6.9 6.9 8959.3 8959.3 84.7 W99CW020 PEM TBD COWLITZ, WA 507810106 Y 0 0.0 0.1 0.1 0 0 85.8 W99CW022 PEM TBD COWLITZ, WA 50729 Y 765 0.0 2.1 2.1 2267.3 2267.3 86.6 W99CW011 PEM TBD COWLITZ, WA Y 125 0.0 0.2 0.2 370.6 370.6 a Cowardin Classification System: PEM = palustrine emergent; PSS = palustrine scrub-shrub; PFO = palustrine forested,E2USN= estuarine unconsoldiated bottom; AW= agricultural wetland (not a Cowardin class). b Wetland classes based on Hydrogeomorphic Assessment Guidebook for Tidal Wetlands of the Oregon Coast, TBD = to be determined due to lack of site access. c Y = Oregon LNG surveyed wetland, N = no site access – proxy data used. e Permanent impacts on wetlands requiring long term restoration including the functional conversion of forested wetlands to scrub-shrub wetlands, or conversation of scrub-shrub wetlands to emergent wetlands. f Temporary impacts on wetlands that are expected to recover to preconstruction conditions. g Volumes based on a 10-foot width, 8-foot average depth, and the length of the pipeline through each wetland. Volumes include the temporary excavation of material from the trench and the replacement of the excavated material to backfill the trench but excludes temporary spoils piles in wetlands from trench excavation or temporary soil disturbances in temporary workspaces from equipment operation or other construction activities. Lewis HUC 4 Subasin - Cowlitz County, WA Lower Columbia Clastskanie HUC 4 Subasin - Cowlitz County, WA G1‐7 ---PAGE BREAK--- Milepost Stream ID Stream Width (feet) Waterbody County/State Crossing Method FERC Waterbody Type Stream Type Oregon State Class Miles to Salmonid Habitat In-Water Work Window 1.0 S99CL001 110 Adair Slough CLATSOP, OR HDD Major Perennial Category 3 0.00 Nov. 1- Feb. 28 1.5 S5BCL074 20 Vera Creek CLATSOP, OR Flume Intermediate Perennial Category 3 0.49 Nov. 1- Feb. 28 2.6 S40CL001 50 Tributary of Lewis and Clark River CLATSOP, OR Open cut Intermediate Perennial Category 5 0.47 Nov. 1- Feb. 28 3.1 S40CL002 1250 Lewis and Clark River CLATSOP, OR HDD Major Perennial Category 5 0.00 Nov. 1- Feb. 28 3.5 S99CL019 60 Tributary of Jeffers Slough CLATSOP, OR Flume Intermediate Intermittent Category 3 0.23 Nov. 1- Feb. 28 4.1 S5BCL059 1.5 Tributary of Barrett Slough CLATSOP, OR Flume Minor Perennial Category 3 0.10 Nov. 1- Feb. 28 4.2 S5BCL062 2 Tributary of Barrett Slough CLATSOP, OR Open cut Minor Perennial Category 3 0.12 Nov. 1- Feb. 28 4.3 S5BCL063 4.5 Tributary of Barrett Slough CLATSOP, OR Open cut Minor Intermittent Category 3 0.06 Nov. 1- Feb. 28 4.5 S5BCL064 12 Barrett Slough CLATSOP, OR Flume Intermediate Intermittent Category 3 0.00 Nov. 1- Feb. 28 4.6 S5BCL066 3 Tributary of Barrett Slough CLATSOP, OR Open cut Minor Perennial Category 3 0.11 Nov. 1- Feb. 28 4.8 S5BCL068 8 Tributary of Green Slough CLATSOP, OR Open cut Minor Intermittent Category 3 0.30 Nov. 1- Feb. 28 4.8 S5BCL069 7 Tributary of Green Slough CLATSOP, OR Open cut Minor Intermittent Category 3 0.40 Nov. 1- Feb. 28 4.9 S5BCL070 2 Unnamed CLATSOP, OR Open cut Minor Intermittent NA 0.20 Nov. 1- Feb. 28 5.0 S5BCL071 5 Unnamed CLATSOP, OR HDD Minor Intermittent NA 0.54 Nov. 1- Feb. 28 5.2 S5BCL072 7 Tributary of Lewis and Clark River CLATSOP, OR HDD Minor Intermittent Category 5 0.09 Nov. 1- Feb. 28 5.2 S99CL111 340 Lewis and Clark River CLATSOP, OR HDD Major Perennial Category 5 0.00 Nov. 1- Feb. 28 5.4 S99CL034 20 Tributary of Lewis and Clark River CLATSOP, OR HDD Intermediate Perennial Category 5 0.08 Nov. 1- Feb. 28 5.5 S99CL024 13 Tributary of Lewis and Clark River CLATSOP, OR Open cut Intermediate Perennial Category 5 0.10 Nov. 1- Feb. 28 5.7 S99CL064 340 Lewis and Clark River CLATSOP, OR HDD Major Intermittent Category 5 0.00 Nov. 1- Feb. 28 5.8 S38CL003 8 Tributary of Lewis and Clark River CLATSOP, OR HDD Minor Perennial Category 5 0.41 Nov. 1- Feb. 28 7.9 S1BCL001 10 Heckard Creek CLATSOP, OR Flume Intermediate Intermittent Category 5 0.02 July 1- Sept. 15 8.1 S1BCL050 10 Unnamed CLATSOP, OR Open cut Intermediate Intermittent NA 0.13 July 1- Sept. 15 8.6 S1BCL002 4 Tributary of Lewis and Clark River CLATSOP, OR Open cut Minor Perennial Category 5 1.17 July 1- Sept. 15 8.8 S1BCL018 25 Tributary of Lewis and Clark River CLATSOP, OR Flume Intermediate Intermittent Category 5 1.29 July 1- Sept. 15 9.1 S1BCL003 3 Tributary of Lewis and Clark River CLATSOP, OR Open cut Minor Perennial Category 5 0.86 July 1- Sept. 15 9.3 S1BCL004 4 Tributary of Lewis and Clark River CLATSOP, OR Open cut Minor Intermittent Category 5 0.82 July 1- Sept. 15 9.7 S1BCL006 3 Tributary of Lewis and Clark River CLATSOP, OR Open cut Minor Intermittent Category 5 0.96 July 1- Sept. 15 9.7 S1BCL005 8 Tributary of Lewis and Clark River CLATSOP, OR Open cut Minor Intermittent Category 5 0.97 July 1- Sept. 15 9.9 S1BCL007 3 Tributary of Lewis and Clark River CLATSOP, OR Open cut Minor Intermittent Category 5 0.97 July 1- Sept. 15 10.0 S1BCL008 10 Tributary of Lewis and Clark River CLATSOP, OR Flume Intermediate Intermittent Category 5 0.98 July 1- Sept. 15 11.0 S99CL018 35 Lewis and Clark River CLATSOP, OR HDD Intermediate Perennial Category 5 0.00 July 15- Sept. 15 12.8 S1BCL016 8 Tributary of Speelyai Creek CLATSOP, OR Flume Minor Perennial Category 5 1.03 July 1- Sept. 15 13.8 S5BCL040 0.8 Tributary of Youngs River CLATSOP, OR Flume Minor Perennial Category 5 2.02 July 15- Sept. 15 13.8 S5BCL041 2 Tributary of Youngs River CLATSOP, OR Flume Minor Perennial Category 5 2.03 July 15- Sept. 15 13.9 S5BCL042 5 Tributary of Youngs River CLATSOP, OR Open cut Minor Perennial Category 5 2.05 July 15- Sept. 30 Table G1-3 Waterbodies Crossed by the Oregon LNG Pipeline Lower Columbia HUC 4 Subbasin G1‐8 ---PAGE BREAK--- Milepost Stream ID Stream Width (feet) Waterbody County/State Crossing Method FERC Waterbody Type Stream Type Oregon State Class Miles to Salmonid Habitat In-Water Work Window Table G1-3 Waterbodies Crossed by the Oregon LNG Pipeline 13.9 S5BCL043 20 Tributary of Youngs River CLATSOP, OR Open cut Intermediate Intermittent Category 5 2.08 July 15- Sept. 30 14.1 S5BCL045 8 Tributary of Youngs River CLATSOP, OR Flume Minor Intermittent Category 5 2.15 July 15- Sept. 30 14.2 S5BCL044 5 Tributary of Youngs River CLATSOP, OR Flume Minor Perennial Category 5 2.16 July 15- Sept. 30 14.8 S5BCL038 2 Tributary of Youngs River CLATSOP, OR Open cut Minor Perennial Category 5 2.28 July 15- Sept. 30 15.3 S5BCL035 3 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 2.09 July 15- Sept. 30 15.6 S5BCL030 4 Tributary of Youngs River CLATSOP, OR Flume Minor Intermittent Category 5 2.11 July 15- Sept. 30 15.6 S5BCL034 4 Tributary of Youngs River CLATSOP, OR Flume Minor Perennial Category 5 2.08 July 15- Sept. 30 15.8 S5BCL031 5 Tributary of Youngs River CLATSOP, OR Flume Minor Perennial Category 5 2.25 July 15- Sept. 30 16.1 S99CL016 7 Bayney Creek CLATSOP, OR Flume Minor Perennial Category 5 2.49 July 15- Sept. 30 16.6 S5BCL032 3 Tributary of Youngs River CLATSOP, OR Open cut Minor Perennial Category 5 2.98 July 15- Sept. 30 17.3 S5BCL077 6 Tributary of Youngs River CLATSOP, OR Flume Minor Intermittent Category 5 3.61 July 15- Sept. 30 17.8 S5BCL078 6 Tributary of Youngs River CLATSOP, OR Open cut Minor Perennial Category 5 4.05 July 15- Sept. 30 17.8 S5BCL079 5 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 4.09 July 15- Sept. 30 17.9 S5BCL080 4 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 4.20 July 15- Sept. 30 18.4 S5BCL076 4 Tributary of Rock Creek CLATSOP, OR Flume Minor Intermittent Category 5 4.64 July 15- Sept. 30 18.5 S1BCL009 10 Rock Creek CLATSOP, OR Flume Intermediate Perennial Category 3B 4.78 July 15- Sept. 30 18.8 S1BCL010 5 Tributary of Youngs River CLATSOP, OR Open cut Minor Perennial Category 5 5.08 July 15- Sept. 30 19.0 S1BCL011 6 Tributary of Youngs River CLATSOP, OR Flume Minor Intermittent Category 5 5.25 July 15- Sept. 30 19.1 S1BCO012 3 Unnamed CLATSOP, OR Open cut Minor Perennial NA 2.93 July 15- Sept. 30 19.3 S1BCL014 8 Osgood Creek CLATSOP, OR Flume Minor Intermittent Category 5 5.55 July 15- Sept. 30 19.6 S2BCL013A 7 Tributary of Osgood Creek CLATSOP, OR Flume Minor Perennial Category 5 5.79 July 15- Sept. 30 20.1 S2BCL013B 35 Fox Creek CLATSOP, OR Flume Intermediate Perennial Category 5 6.10 July 15- Sept. 30 21.4 S38CL013 3 South Fork Youngs River CLATSOP, OR Flume Minor Perennial Category 5 7.16 July 15- Sept. 30 21.6 S42CL003 3 Unnamed CLATSOP, OR Open cut Minor Perennial NA 2.83 July 15- Sept. 30 21.8 S5BCL058 15 Tributary of Youngs River CLATSOP, OR Flume Intermediate Perennial Category 5 7.58 July 15- Sept. 30 22.1 S5BCL049 2.5 Tributary of Youngs River CLATSOP, OR Flume Minor Perennial Category 5 7.85 July 15- Sept. 30 22.2 S5BCL048 5 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 7.92 July 15- Sept. 30 22.5 S6BCL016 2 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.20 July 15- Sept. 30 22.6 S6BCL014 4 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.29 July 15- Sept. 30 22.6 S6BCL013 1 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.28 July 15- Sept. 30 22.6 S6BCL015 2 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.23 July 15- Sept. 30 22.8 S6BCL017 3.5 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.51 July 15- Sept. 30 22.8 S6BCL010 2 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.49 July 15- Sept. 30 22.8 S6BCL011 2 Tributary of Youngs River CLATSOP, OR Open cut Minor Intermittent Category 5 8.45 July 15- Sept. 30 22.9 S6BCL018 4 Tributary of Fall Creek CLATSOP, OR Open cut Minor Intermittent Category 5 8.62 July 15- Sept. 30 23.0 S6BCL019 20 Tributary of Fall Creek CLATSOP, OR Flume Intermediate Perennial Category 5 8.66 July 15- Sept. 30 G1‐9 ---PAGE BREAK--- Milepost Stream ID Stream Width (feet) Waterbody County/State Crossing Method FERC Waterbody Type Stream Type Oregon State Class Miles to Salmonid Habitat In-Water Work Window Table G1-3 Waterbodies Crossed by the Oregon LNG Pipeline 23.1 S6BCL020 3 Tributary of Fall Creek CLATSOP, OR Open cut Minor Intermittent Category 5 8.77 July 15- Sept. 30 23.4 S38CL014 10 Fall Creek CLATSOP, OR Flume Intermediate Perennial Category 5 9.11 July 15- Sept. 30 24.3 S5BCL016 3.5 Tributary of Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 5 2.36 July 1- Aug. 31 24.4 S5BCL018 6 Tributary of Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 5 2.32 July 1- Aug. 31 24.4 S5BCL017 3.5 Tributary of Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 5 2.34 July 1- Aug. 31 24.8 S2BCL002 25 Tributary of Fishhawk Creek CLATSOP, OR Open cut Intermediate Intermittent Category 4C 2.08 July 1- Aug. 31 24.8 S2BCL001 7 Tributary of Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 5 2.09 July 1- Aug. 31 25.1 S2BCL003 8 Tributary of Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 1.97 July 1- Aug. 31 25.2 S2BCL004 3 Tributary of Fishhawk Creek CLATSOP, OR Open cut Minor Perennial Category 4C 1.96 July 1- Aug. 31 25.2 S2BCL005 10 Tributary of Fishhawk Creek CLATSOP, OR Flume Intermediate Intermittent Category 4C 1.96 July 1- Aug. 31 25.3 S2BCL007 3 Tributary of Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 1.95 July 1- Aug. 31 25.4 S2BCL008A 15 Tributary of Fishhawk Creek CLATSOP, OR Flume Intermediate Perennial Category 4C 1.95 July 1- Aug. 31 25.7 S2BCL009 10 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Intermediate Perennial Category 4C 4.29 July 1- Aug. 31 25.7 S2BCL010 4 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 4.27 July 1- Aug. 31 25.9 S2BCL012 10 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Intermediate Intermittent Category 4C 4.19 July 1- Aug. 31 26.3 S5BCL019 1.2 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 3.87 July 1- Aug. 31 26.5 S5BCL029 1.5 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 3.68 July 1- Aug. 31 26.6 S5BCL027 1 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 3.63 July 1- Aug. 31 26.6 S5BCL028 2 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 3.63 July 1- Aug. 31 26.8 S5BCL025 1.4 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 3.41 July 1- Aug. 31 26.8 S5BCL023 1.3 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 3.40 July 1- Aug. 31 27.0 S5BCL022 3 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 3.27 July 1- Aug. 31 27.2 S5BCL021 6 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 3.05 July 1- Aug. 31 27.3 S5BCL020 1.8 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 2.97 July 1- Aug. 31 27.4 S5BCL015 4 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 2.89 July 1- Aug. 31 27.6 S5BCL014 2.4 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 2.68 July 1- Aug. 31 27.8 S5BCL012 2 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 2.55 July 1- Aug. 31 27.8 S5BCL013 2 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 2.56 July 1- Aug. 31 27.9 S5BCL011 3 Tributary of Little Fishhawk Creek CLATSOP, OR Open cut Minor Intermittent Category 4C 2.46 July 1- Aug. 31 28.1 S5BCL010 3.5 Tributary of Little Fishhawk Creek CLATSOP, OR Flume Minor Perennial Category 4C 2.35 July 1- Aug. 31 28.4 S5BCL007 6 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 1.24 July 1- Sept. 15 28.5 S5BCL005 4 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 1.19 July 1- Sept. 15 28.5 S5BCL004 7 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 1.13 July 1- Sept. 15 29 S5BCL001 3 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.79 July 1- Sept. 15 29 S5BCL002 2 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.81 July 1- Sept. 15 Nehalem HUC 4 Subasin G1‐10 ---PAGE BREAK--- Milepost Stream ID Stream Width (feet) Waterbody County/State Crossing Method FERC Waterbody Type Stream Type Oregon State Class Miles to Salmonid Habitat In-Water Work Window Table G1-3 Waterbodies Crossed by the Oregon LNG Pipeline 29.4 S6BCL007 1 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.81 July 1- Sept. 15 29.4 S6BCL008 1.5 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.80 July 1- Sept. 15 29.5 S6BCL005 6 Tributary of East Humbug Creek CLATSOP, OR Flume Minor Perennial Category 4A 0.78 July 1- Sept. 15 29.5 S6BCL006 7 Tributary of East Humbug Creek CLATSOP, OR Flume Minor Perennial Category 4A 0.79 July 1- Sept. 15 29.9 S6BCL004 5 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.59 July 1- Sept. 15 30.9 S2BCL021 2 Tributary of East Humbug Creek CLATSOP, OR Open cut Minor Intermittent Category 4 0.72 July 1- Sept. 15 31.4 S2BCL008B 15 Alder Creek CLATSOP, OR Flume Intermediate Perennial Category 4 0.00 July 1- Sept. 15 31.6 S6BCL001 3.5 Tributary of Alder Creek CLATSOP, OR Open cut Minor Intermittent Category 4 0.21 July 1- Sept. 15 32 S3BCL002 6 Tributary of Nehalem River CLATSOP, OR Open cut Minor Intermittent Category 5 0.68 July 1- Aug. 31 32 S3BCL001 6 Tributary of Nehalem River CLATSOP, OR Open cut Minor Intermittent Category 5 0.69 July 1- Aug. 31 32.1 S3BCL004 6 Tributary of Nehalem River CLATSOP, OR Open cut Minor Intermittent Category 5 0.66 July 1- Aug. 31 32.1 S3BCL003 4 Tributary of Nehalem River CLATSOP, OR Open cut Minor Intermittent Category 5 0.67 July 1- Aug. 31 32.3 S3BCL005 8 Tributary of Nehalem River CLATSOP, OR Open cut Minor Intermittent Category 5 0.67 July 1- Aug. 31 32.3 S3BCL006 10 Tributary of Nehalem River CLATSOP, OR Open cut Intermediate Intermittent Category 5 0.67 July 1- Aug. 31 32.4 S3BCL007 8 Tributary of Nehalem River CLATSOP, OR Open cut Minor Intermittent Category 5 0.68 July 1- Aug. 31 33.5 S99CL108 120 Nehalem River CLATSOP, OR HDD Major Perennial Category 5 0.00 July 1- Aug. 31 34.4 S5BCL046 2 Tributary of Nehalem River CLATSOP, OR Flume Minor Perennial Category 5 1.06 July 1- Aug. 31 36.2 S3BCL101 10 Unnamed CLATSOP, OR Flume Intermediate Perennial NA 0.26 July 1- Aug. 31 36.3 S3BCL102 5 Unnamed CLATSOP, OR Flume Minor Perennial NA 0.27 July 1- Aug. 31 37.5 S8BCL004 5 Tributary of NF Quartz Creek CLATSOP, OR Flume Minor Perennial Category 5 0.47 July 1- Aug. 15 37.7 S8BCL003 2.3 Tributary of NF Quartz Creek CLATSOP, OR Open cut Minor Intermittent Category 5 0.54 July 1- Aug. 15 38.5 S8BCL001 2 Tributary of SF Quartz Creek CLATSOP, OR Flume Minor Perennial Category 3 1.28 July 1- Aug. 15 39.6 S1BCL029 2.6 Tributary of Military Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.28 July 1- Aug. 15 39.8 S1BCL027 1.5 Tributary of Military Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.17 July 1- Aug. 15 39.8 S1BCL028 2.6 Tributary of Military Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.18 July 1- Aug. 15 41 S8BCL005 20 Rock Creek CLATSOP, OR HDD Intermediate Perennial Category 4A 0.00 July 1- Aug. 31 42.3 S8BCL009 11 Tributary of South Fork Rock Creek CLATSOP, OR Flume Intermediate Perennial Category 4A 0.00 July 1- Aug. 31 42.7 S1BCL020 6 Tributary of South Fork Rock Creek CLATSOP, OR Flume Minor Perennial Category 4A 0.03 July 1- Aug. 31 43.1 S1BCL021 15 South Fork Rock Creek CLATSOP, OR HDD Intermediate Perennial Category 4A 0.00 July 1- Aug. 31 43.4 S1BCL022 12 Bear Creek CLATSOP, OR HDD Intermediate Perennial Category 4A 0.00 July 1- Aug. 31 43.5 S1BCL023 1.3 Tributary of Bear Creek CLATSOP, OR HDD Minor Intermittent Category 4A 0.04 July 1- Aug. 31 43.7 S1BCL024 1.6 Tributary of Bear Creek CLATSOP, OR Flume Minor Perennial Category 4A 0.09 July 1- Aug. 31 43.9 S1BCL025 4 Tributary of Bear Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.12 July 1- Aug. 31 44 S1BCL026 3 Tributary of Bear Creek CLATSOP, OR Open cut Minor Intermittent Category 4A 0.11 July 1- Aug. 31 44.2 S1BTI001 6 Bear Creek Tillamook, OR Flume Minor Perennial Category 4A 0.18 July 1- Aug. 31 44.3 S1BTI002 1.8 Tributary of Bear Creek Tillamook, OR Open cut Minor Intermittent Category 4A 0.27 July 1- Aug. 31 G1‐11 ---PAGE BREAK--- Milepost Stream ID Stream Width (feet) Waterbody County/State Crossing Method FERC Waterbody Type Stream Type Oregon State Class Miles to Salmonid Habitat In-Water Work Window Table G1-3 Waterbodies Crossed by the Oregon LNG Pipeline 44.8 S5BTI001 8 Tributary of Wolf Creek Tillamook, OR Flume Minor Perennial Category 4A 2.70 July 1- Aug. 31 45.1 S1BTI003 4 Tributary of Wolf Creek Tillamook, OR Open cut Minor Intermittent Category 4A 2.41 July 1- Aug. 31 47.6 S6BCO002 30 North Fork Wolf Creek COLUMBIA, OR Flume Intermediate Perennial g y 0.00 July 1- Aug. 31 48.3 S1BCO000 3 Tributary of North Fork Wolf Creek COLUMBIA, OR Flume Minor Perennial Category 3 0.64 July 1- Aug. 31 50.5 S3BCO012 30 Clear Creek COLUMBIA, OR Flume Intermediate Perennial Category 3 0.03 July 1- Aug. 31 53.6 S3BCO002 1 Fall Creek COLUMBIA, OR Flume Minor Perennial NA 2.28 July 1- Aug. 31 55.7 S3BCO107 10 Cedar Creek COLUMBIA, OR Flume Intermediate Perennial NA 0.01 July 1- Aug. 31 55.8 S3BCO106 4 Tributary of Cedar Creek COLUMBIA, OR Flume Minor Perennial NA 0.21 July 1- Aug. 31 57.7 S3BCO101B 10 Braided Channel to Rock Creek COLUMBIA, OR HDD Intermediate Perennial Category 3 0.00 July 1- Aug. 31 57.7 S3BCO100 10 Tributary of Rock Creek COLUMBIA, OR HDD Intermediate Perennial Category 3 0.01 July 1- Aug. 31 57.7 S3BCO101 30 Rock Creek COLUMBIA, OR HDD Intermediate Perennial Category 3 0.00 July 1- Aug. 31 63.8 S3BCO014 30 Nehalem River COLUMBIA, OR HDD Intermediate Perennial Category 4A 0.00 July 1- Aug. 31 66.3 S3BCO103 1 Tributary of Oak Ranch Creek COLUMBIA, OR Open cut Minor Intermittent NA 0.68 July 1- Aug. 31 67.7 S6BCO004 3 Unnamed COLUMBIA, OR Open cut Minor Intermittent NA 0.38 July 1- Aug. 31 68 S6BCO003 3 Unnamed COLUMBIA, OR Flume Minor Perennial NA 0.49 July 1- Aug. 31 70.2 S3BCO003 1 Tributary of Clatskanie River COLUMBIA, OR Flume Minor Perennial Category 3 0.59 July 1- Aug. 31 70.7 S99CO020 18.5 Clatskanie River COLUMBIA, OR Flume Intermediate Perennial Cat 2, Cat 3, Cat 3B, Cat 4A 0.00 July 1- Aug. 31 71 S99CO021 1 Unnamed COLUMBIA, OR Flume Minor Perennial NA 0.19 July 1- Aug. 31 71.8 S5BCO001 2 Little Clatskanie River COLUMBIA, OR Flume Minor Perennial Category 3 0.06 July 1- Aug. 31 72.7 S3BCO008 2 Tributary of Milton Creek COLUMBIA, OR Flume Minor Perennial/Inte Category 3 0.24 July 1- Aug. 31 73 S3BCO010 12 Milton Creek COLUMBIA, OR Flume Intermediate Perennial Category 3B 0.02 July 15-Sept 15 73.5 S1BCO004 3 Apilton Creek COLUMBIA, OR Open cut Minor Intermittent NA 0.54 July 15-Sept 15 73.6 S1BCO005 1 Tributary of Apilton Creek COLUMBIA, OR Open cut Minor Intermittent NA 0.58 July 15-Sept 15 74.5 S5BCO011 5 Unnamed COLUMBIA, OR Flume Minor Perennial NA 0.12 July 15-Sept 15 74.6 S5BCO010 30 Unnamed COLUMBIA, OR Flume Intermediate Perennial NA 0.12 July 15-Sept 15 74.9 S6BCO001 22 Milton Creek COLUMBIA, OR Flume Intermediate Perennial Category 3 0.00 July 15-Sept 15 Lower Columbia Clastskanie HUC 4 Subasin 76.3 S3BCO110 1 Tributary of Merril Creek COLUMBIA, OR Open cut Minor Intermittent NA 0.24 July 15-Sept 15 76.4 S3BCO017 35 Merrill Creek COLUMBIA, OR Flume Intermediate Perennial NA 0.00 July 15-Sept 15 78.2 S2BCO009 3 Tributary of Merrill Creek COLUMBIA, OR Open cut Minor Intermittent Category 3 0.38 July 15-Sept 15 78.4 S3BCO122 10 Tributary of Merrill Creek COLUMBIA, OR Flume Intermediate Perennial Category 3 0.20 July 15-Sept 15 79 S3BCO120 1 Tributary of Merrill Creek COLUMBIA, OR Open cut Minor Intermittent Category 3 0.87 July 15-Sept 15 79 S3BCO119 1 Tributary of Merrill Creek COLUMBIA, OR Open cut Minor Intermittent Category 3 0.92 July 15-Sept 15 79.9 S3BCO115 1 Tributary of Merrill Creek COLUMBIA, OR Flume Minor Perennial Category 3 2.01 July 15-Sept 15 Lower Columbia Clastskanie HUC 4 Subasin Lower Willamette HUC 4 Subbasin G1‐12 ---PAGE BREAK--- Milepost Stream ID Stream Width (feet) Waterbody County/State Crossing Method FERC Waterbody Type Stream Type Oregon State Class Miles to Salmonid Habitat In-Water Work Window Table G1-3 Waterbodies Crossed by the Oregon LNG Pipeline 81.6 S99CO011 280 Deer Island Slough COLUMBIA, OR Flume Major Perennial Category 3B 0.46 July 15-Sept 15 82.0 S3BCO123 20 Dyna Nobel Channel COLUMBIA, OR HDD Intermediate Perennial Category 3 0.45 July 15-Sept 15 82.3 S99CO014 3300 Columbia River COLUMBIA, OR HDD Major Perennial Cat 2, Cat 3, Cat 3B, Cat 4A 0.00 Novr 1- Feb 28 83.3 S99CW020 10 Burris Creek COWLITZ, WA Flume Intermediate Perennial NA 0.00 Aug 1-Aug 31 85.8 S99CW021 2 Unnamed COWLITZ, WA Flume Minor Perennial NA 0.36 Aug 1-Aug 31 86 S99CW022 2 Unnamed COWLITZ, WA Flume Minor Perennial NA 0.31 Aug 1-Aug 31 86.5 S99CW023 3 Unnamed COWLITZ, WA Open cut Minor Intermittent NA 0.48 Aug 1-Aug 31 86.7 S99CW025 3 Unnamed COWLITZ, WA Open cut Minor Intermittent NA 0.40 Aug 1-Aug 31 86.8 S99CW026 3 Unnamed COWLITZ, WA Flume Minor Perennial NA 0.39 Aug 1-Aug 31 Category 1: All standards are met. (This category is not used.) Category 2: Attaining - Some of the pollutant standards are met. Category 3: Insufficient data to determine whether a standard is met. 3B: Potential concern - Some data indicate nonattainment of a criterion, but data are insufficient to assign another category. HDD: horizontal directional drill Open cut: Conventional Open cut. Applicable to intermittent and ephemeral streams that are not fish-bearing, fish-bearing intermittent or ephemeral streams if dry at the time of construction, and some perennial streams Category 4: Water is water quality limited but a Total Maximum Daily Load (TMDL) is not needed. This category encompasses: 4A: TMDL approved - needed to attain applicable water quality standards have been approved. 4B: Other pollution control requirements are expected to address all pollutants and will attain water quality standards. 4C: Impairment is not caused by a pollutant flow or lack of flow is not considered a pollutant). Category 5: Water is water quality limited and a TMDL is needed, Section 303(d) list. Cat = category TMDL = total maximum daily load; NA = not applicable. Precision loss may occur because of rounding. Crossing Method Flume: Water will be diverted around the construction area using a flume or flumes to allow a dry Open cut. If no fish are present, the crossing method may be modified with a dam and pump arrangement to convey G1‐13 ---PAGE BREAK--- ---PAGE BREAK--- APPENDIX G2 LANDSLIDE HAZARD AREAS CROSSED BY THE OREGON LNG PIPELINE ---PAGE BREAK--- ---PAGE BREAK--- G2-1 Appendix G2 Landslide Hazard Areas Crossed by the Oregon LNG Pipeline Mapped Landslide Hazard a Type of Landslide Hazard References From MP To MP 6.5 7.8 Landslide Topography; Potential Rapidly Moving Landslide; Potential Gullying/Erosion/Debris Flow Schlicker et al., 1972; Burns et al., 2011; Hofmeister, 2002; CH2M HILL, 2009 8.0 8.6 Landslide Topography Schlicker et al., 1972; Burns et al., 2011 8.7 10.2 Landslide Topography; Potential Gullying/Erosion/Debris Flow Schlicker et al., 1972; Burns et al., 2011 11.2 15.6 Inactive Landslide; Landslide Topography; Potential Rapidly Moving Landslide; Potential Gullying/Erosion/Debris Flow Schlicker et al., 1972; Burns et al., 2011; Hofmeister, 2002; CH2M HILL, 2009 16.5 17.8 Mass Movement Topography, Landslide Topography Schlicker et al., 1972; Burns et al., 2011; CH2M HILL, 2009 17.4 17.6 Potential Rapidly Moving Landslide Hazard Burns et al., 2011; Hofmeister, 2002. 17.8 b 21.5 Mass Movement Topography, Landslide Topography; Potential Rapidly Moving Landslide; Potential Gullying/Erosion/Debris Flow Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 21.6 22.1 Potential Rapidly Moving Landslide Hofmeister, 2002 22.1 23.8 Mass Movement Topography; Potential Gullying/Erosion/Debris Flow Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 23.8 b 25.3 Mass Movement Topography; Potential Rapidly Moving Landslide; Potential Gullying/Erosion/Debris Flow Beaulieu, 1973; Burns et al., 2011; Hofmeister, 2002; CH2M HILL, 2009 25.0 25.1 2007–2008 Landslides—2,000 to 3,500 feet from alignment CH2M HILL, 2009 25.3 b 26.2 b Mass Movement Topography Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 26.2 27.2 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2009 26.9 2007–2008 Landslide—1,200 feet from alignment CH2M HILL, 2009 27.3 30.3 Mass Movement Topography; Potential Rapidly Moving Landslide; Potential Gullying/Erosion/Debris Flow Beaulieu, 1973; Hofmeister, 2002; CH2M HILL, 2009 30.7 31.9 b Mass Movement Topography; Potential Rapidly Moving Landslide Beaulieu, 1973; Hofmeister, 2002; CH2M HILL, 2009 31.9 32.3 Mass Movement Topography Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 33.0 33.3 Mass Movement Topography Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 34.2 37.2 b Mass Movement Topography Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 35.7 Recent Landslide—2,500 feet from alignment Burns et al., 2011 36.1 Recent Landslides—1,300 to 1,500 feet from alignment Burns et al., 2011 37.2 Recent Landslide—1,900 feet from alignment Burns et al., 2011; CH2M HILL, 2009 37.5 38.1 Potential Rapidly Moving Landslide; Potential Gullying/Erosion/Debris Flow Hofmeister, 2002, CH2M HILL, 2009 37.7 38.8 Mass Movement Topography Beaulieu, 1973; Burns et al., 2011; CH2M HILL, 2009 38.7 39.0 Potential Rapidly Moving Landslide Hofmeister, 2002 38.8 Recent Landslide—1,300 feet from alignment Burns et al., 2011 39.0 39.8 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2009 40.2 Recent Landslide—400 feet from alignment Burns et al., 2011 40.2 41.0 Potential Rapidly Moving Landslide Hofmeister, 2002 ---PAGE BREAK--- G2-2 Appendix G2 Landslide Hazard Areas Crossed by the Oregon LNG Pipeline Mapped Landslide Hazard a Type of Landslide Hazard References From MP To MP 42.0 42.8 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2009 43.1 43.2 Potential Rapidly Moving Landslide Hofmeister, 2002 41.5 44.7 Mass Movement Topography; Potential Rapidly Moving Landslide Beaulieu, 1973; CH2M HILL, 2009; Hofmeister, 2002 45.0 Recent Landslide - 300 feet from alignment CH2M HILL, 2013 45.2 Recent Landslide – 300 feet from alignment Burns et al., 2011 45.6 45.6 Potential Gullying/Erosion/Debris Flow, Recent Landslide – 500 feet from alignment CH2M HILL, 2013, Burns et al., 2011 46.3 b Recent Landslides – 500 feet from alignment Burns et al., 2011 46.5 b Recent Landslide – 400 feet from alignment Burns et al., 2011 46.3 46.6 Mass Movement Topography, Potential Rapidly Moving Landslide Burns et al., 2011; Hofmeister, 2002 46.9 47.3 Mass Movement Topography Burns et al., 2011 47.5 Recent Landslide – 1,500 feet from alignment Burns et al., 2011 47.6 49.0 Landslide Topography, Potential Gullying/Erosion/Debris Flow, Potential Rapidly Moving Landslide CH2M HILL, 2013; Hofmeister, 2002 49.2 49.4 Landslide Topography CH2M HILL, 2013 49.4 b 49.8 b Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 50.0 50.1 Potential Rapidly Moving Landslide Hofmeister, 2002 50.6 50.6 Potential Rapidly Moving Landslide Hofmeister, 2002 50.8 50.8 Potential Rapidly Moving Landslide Hofmeister, 2002 51.4 51.9 b Landslide Topography, Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 52.8 52.9 Potential Rapidly Moving Landslide Hofmeister, 2002 53.4 53.6 Potential Rapidly Moving Landslide, Potential Gullying/Erosion/Debris Flow Hofmeister, 2002; CH2M HILL, 2013 53.8 54.2 Landslide Topography CH2M HILL, 2013 54.6 54.7 Landslide Topography CH2M HILL, 2013 54.9 55.7 Landslide Topography CH2M HILL, 2013 55.9 55.9 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 55.9 56.4 Landslide Topography CH2M HILL, 2013 57.4 57.7 Landslide Topography CH2M HILL, 2013 57.8 58.3 Potential Rapidly Moving Landslide, Landslide Topography Hofmeister, 2002; CH2M HILL, 2013 59.2 59.3 Landslide Topography CH2M HILL, 2013 59.9 60.1 Landslide Topography CH2M HILL, 2013 60.9 61.1 Landslide Topography CH2M HILL, 2013 62.0 62.0 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 62.3 62.5 Landslide Topography CH2M HILL, 2013 ---PAGE BREAK--- G2-3 Appendix G2 Landslide Hazard Areas Crossed by the Oregon LNG Pipeline Mapped Landslide Hazard a Type of Landslide Hazard References From MP To MP 62.7 62.7 Potential Rapidly Moving Landslide Hofmeister, 2002 63.4 63.4 Potential Rapidly Moving Landslide Hofmeister, 2002 63.7 Recent Landslide – 2,400 feet from alignment Burns et al., 2011 63.8 Recent Landslides – 1,300 to 2,100 feet from alignment Burns et al., 2011 63.9 63.9 Potential Rapidly Moving Landslide Hofmeister, 2002 64.5 64.6 Landslide Topography CH2M HILL, 2013 65.3 65.4 Landslide Topography CH2M HILL, 2013 65.8 65.9 Landslide Topography CH2M HILL, 2013 66.2 66.3 Landslide Topography CH2M HILL, 2013 66.7 66.7 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 67.2 67.3 Landslide Topography CH2M HILL, 2013 67.6 68.0 Landslide Topography, Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 69.1 69.1 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 69.7 69.9 Landslide Topography CH2M HILL, 2013 70.2 70.2 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 70.6 71.3 Landslide Topography; Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 71.6 71.7 Landslide Topography CH2M HILL, 2013 71.8 71.8 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 72.1 72.9 Landslide Topography, Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 73.6 73.6 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 73.7 74.2 Landslide Topography, Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 75.4 75.4 Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 76.1 76.8 Landslide Topography, Potential Gullying/Erosion/Debris Flow CH2M HILL, 2013 77.9 79.3 Landslide Deposits, Landslide Topography Burns et al., 2011; CH2M HILL, 2013 85.6 86.0 Mapped Deep-Seated Composite Landslide, Landslide Topography DNR, 2010; CH2M HILL, 2013 86.3 86.4 Mapped Deep-Seated Composite Landslide DNR, 2010; CH2M HILL, 2013 86.6 86.8 Mapped Deep-Seated Rotational Landslide DNR, 2010; CH2M HILL, 2013 ---PAGE BREAK--- G2-4 Appendix G2 Landslide Hazard Areas Crossed by the Oregon LNG Pipeline Mapped Landslide Hazard a Type of Landslide Hazard References From MP To MP a The milepost numbers in this table identify landslide hazards shown on published landslide hazard mapping and on the project-specific landslide inventory/geologic hazard mapping prepared for Oregon LNG. Source documentation is provided in the “References” column of this table. b Milepost numbers adjusted for consistency with CH2M HILL, 2013. References Beaulieu, J.D. 1973. “Environmental Geology of Inland Tillamook and Clatsop Counties.” Oregon Department of Geology and Mineral Industries. Bulletin 79. Burns, W.J., K.A. Mickelson, and E.C Saint-Pierre. 2011. Statewide Landslide Information Database for Oregon (SLIDO) Release 2. Oregon Department of Geology and Mineral Industries. Publication SLIDO-2. CH2M HILL. 2009. Geologic Hazard: Slope Instability/Landslide Inventory Maps prepared for Resource Report 6. CH2M HILL. 2013. Geologic Hazard: Slope Instability/Landslide Inventory Map, Attachment 4A to Resource Report 6. Hofmeister, J.R. 2002. Hazard Map of Potential Rapidly Moving Landslides in Western Oregon. Oregon Department of Geology and Mineral Industries. Publication Interpretive Map Series IMS-22. Schlicker, H.G., R.J. Deacon, J.D. Beaulieu, and G.W. Olcott. 1972. Environmental Geology of the Coastal Region of Tillamook and Clatsop Counties, Oregon. Oregon Department of Geology and Mineral Industries. Bulletin 74. Washington State Department of Natural Resources (DNR). 2010. Landslides. Geographic Information Systems data dated June 2010. aspx. Scale: 1: 24,000. Last accessed April 1, 2013. ---PAGE BREAK--- APPENDIX G3 SITE-SPECIFIC WATERBODY CROSSING PLANS ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- ---PAGE BREAK--- 20140811-5160 FERC PDF (Unofficial) 8/11/2014 3:46:27 PM ---PAGE BREAK--- 20140811-5160 FERC PDF (Unofficial) 8/11/2014 3:46:27 PM ---PAGE BREAK--- ---PAGE BREAK--- APPENDIX G4 STREAM CHANNEL ASSESSMENT AND SCOUR ANALYSIS ---PAGE BREAK--- ---PAGE BREAK--- T E C H N I C A L M E M O R A N D U M Channel Response Matrix for Pipeline Crossings of Perennial Endangered Species Act Streams PREPARED FOR: Oregon LNG PREPARED BY: Greg White/CH2M HILL Paul Casperson/CH2M HILL Dana Larson/CH2M HILL COPIES: Jay Lorenz/CH2M HILL DATE: May 16, 2013 Introduction This technical memorandum presents the results of a high-level stream channel assessment and scour analysis for the waterbodies crossed by the Oregon Pipeline. Oregon LNG proposes to construct and operate the Oregon Pipeline and associated LNG terminal. The Oregon Pipeline consists of approximately 86.8 miles of 36-inch- diameter pipeline to be constructed between Warrenton, Oregon, and Woodland, Washington, crossing three counties, Clatsop, Columbia, and Cowlitz. The pipeline will cross numerous intermittent and perennial streams and rivers. Specific scour analyses and migration studies may be performed at a later date for specific crossings as required by Oregon LNG and/or permitting agencies. This stream channel assessment combines an evaluation of channel morphology and channel-forming processes to simplify a wide variety of channels into a manageable analysis framework. Channel segments (subreach units) are areas of streams that respond to disturbances in a similar fashion based on similarities in channel-forming processes. The assessment of channel conditions provides a context for evaluating the influence of changes in land management or activities on channel conditions and processes. Major changes in channel morphology (scour) are caused by changes in discharge, sediment supply, and vegetation in the channel. The scour analysis focuses on fluvial-dominated stream channels and provides a first-cut method of identifying stream crossings with a potential for vertical and/or lateral scouring lateral channel migration). Methods Streams with perennial flow regimes and supporting Federal Endangered Species Act (ESA)-listed salmonids were evaluated to determine which pipeline crossings have a predisposition for vertical scouring or lateral migration. A total of 120 streams crossed by the Oregon Pipeline have perennial flow regimes, support ESA-listed salmonids, or have designated critical habitat. Twenty-four of those streams support ESA-listed salmonids or have designated critical habitat. Although some intermittent and ephemeral drainages not supporting ESA-listed salmonids will require further investigation prior to final engineering design, these sites were not included at this time for this study. Stream segment slope (gradient) and channel confinement provide a useful orientation for stream classification and provide a method to distinguish between the possible responses of a stream channel to disturbances. Channel confinement is the ratio of the valley or floodplain width to the channel width. Stream slope at potential pipeline crossings was determined from field reconnaissance surveys. Where field reconnaissance surveys were not conducted, channel gradient was determined from 1:24,000 U.S. Geological Survey (USGS) topographic maps by measuring the distance between a contour line upstream and a contour line of the crossing, or by using Washington 10-meter Digital Elevation Model (DEM) elevations. Channel confinement was determined by measuring the valley width or floodplain (distance between contour lines on either side of the channel at the crossing based on a 1:24,000 USGS topographic map) and comparing this width to the channel width (ordinary high water [OHW] width). ES030613113935PDX 1 ---PAGE BREAK--- CHANNEL RESPONSE MATRIX FOR PIPELINE CROSSINGS OF PERENNIAL ENDANGERED SPECIES ACT STREAMS After determining channel gradient, channel confinement, and valley width at Pipeline crossings, streams were grouped into categories based on their similarities and channel characteristics. Streams with specific similarities are expected to have similar responses to disturbances or be predisposed to specific conditions. These responses or conditions are based in part on the Washington Department of Natural Resources (DNR) Watershed Assessment Methodology (1994) Channel Response Matrix. This approach is also consistent with previous pipeline projects in the area that have included multiple waterbody crossings. In addition, the Rosgen channel type (Rosgen, 1996), which was identified by channel characteristics collected during field reconnaissance surveys, was used to verify and support DNR Channel Response Matrix characteristics. Ephemeral drainages (defined as streams with flows generated by periodic surface runoff along the Pipeline route were not analyzed for scour events. Ephemeral drainages, as defined in the assessment method, only flow during and shortly after a large precipitation event and lack the hydrological and morphological characteristics of a perennial or intermittent stream. Ephemeral drainages may not have a well-defined channel and may be vegetated. Therefore, ephemeral drainages are not considered to have vertical or lateral scour potential. However, ephemeral drainages could experience mass wasting events, such as landslides or slope failure, which could affect the pipeline. Landslide and slope failure potential along the Pipeline are further evaluated in Resource Report 6 — Geologic Resources. In addition to ephemeral drainages, non-ESA intermittent streams were also excluded as they are primarily minor waterways with generally lower scour risk. However, as discussed above, they may still experience mass wasting events that could affect the pipeline. According to Rosgen (1996) and personal communication with Janine Castro of the U.S. Fish and Wildlife Service (Castro, 2009), only streams with a gradient of less than 4 percent typically have the potential for significant lateral scouring at the reach level. Streams with a greater than 4 percent gradient have no functional floodplain and therefore have no, or little, potential for lateral channel migration at the reach scale. At ESA stream crossings and within Federal Emergency Management Agency floodways, the pipeline will be buried at a depth that minimizes the risk of exposure from vertical scour and channel migration. The actual depth of the pipeline will be determined during final engineering to address risks of vertical scour and channel migration. Results Stream channels with similar characteristics are expected to respond to disturbances similarly or be predisposed to specific events. Channel slope can be used as a surrogate for stream energy, which is the dominant aspect controlling channel morphology. Channel confinement controls the characteristics of potential channel responses and manifests the long-term history of a valley (DNR, 1994). Increased entrenchment is one possible channel response to disturbance. Entrenchment is defined as the vertical containment and the degree to which a channel is incised in the valley floor (DNR, 1994). Channel slope and confinement are general indicators of a stream’s transport capacity and the balance between sediment supply and transport capacity (DNR, 1994). The Channel Response Matrix provides a simple method for categorizing potential channel responses in terms of gradient and channel confinement and is based on geomorphic reasoning and professional experience. The matrix differentiates between fluvial and mass-wasting dominated channels. Twenty percent channel slope typically defines the upper limit of fluvially dominated channel systems (DNR, 1994). The DNR Channel Response Matrix shows a channel’s predisposition to specific events given specific channel characteristics. These characteristics are based on channel slope, channel confinement, and valley width. The potential channel responses based on these characteristics include fine sediment deposition, bank erosion, wood loss, debris flow scour, and debris flow deposition. Channel reaches can be grouped into source, transport, and response reaches using gradient as the criterion. Reaches greater than 20 percent gradient are considered source reaches, 3 to 20 percent gradient are transport reaches, and less than 3 percent gradient are response reaches. ES030613113935PDX 2 ---PAGE BREAK--- CHANNEL RESPONSE MATRIX FOR PIPELINE CROSSINGS OF PERENNIAL ENDANGERED SPECIES ACT STREAMS Six gradient groupings are used to generally correspond to gradients associated with changes in channel morphology that reflect relative transport capacity and the response potential (DNR, 1994). The 24 streams evaluated using this methodology were categorized into six distinct groups based on slope, channel width, and confinement (Table Table 2 (located at the end of this technical memorandum) provides specific stream crossing ID numbers, stream slope (gradient valley width, confinement, and vertical and/or lateral scour potential for each of the 24 ESA perennial streams. TABLE 1 Channel Response Matrix for Pipeline Crossings of Perennial Waterbodies and Streams Supporting ESA-listed Salmonids Channel Type Scour Potential of Evaluated Stream Crossings (Vertical/Lateral) None (at Reach Scale)/ Slight Slight/ Moderate Moderate/ Severe Moderate to Severe/ None Severe/ None Severe (Mass Wasting Dominated)/ None Valley Width (VW) > 4 Channel Width (CW) (Unconfined) 11 3 7 1 2 CW < VW < 4 CW (Moderately Confined) 1 VW < 2 CW (Confined) 1 Gradient and Typical Channel Bed Morphology Channel Gradient Percentage (Stream Type) < 1 (Pool-Riffle) 1 to 2 (Pool-Riffle, Plane-Bed) 2 to 4 (Plane-Bed, Forced Pool-Riffle) 4 to 8 (Step-Pool) 8 to 20 (Cascade) > 20 (Colluvial) Source: DNR, 1994. Notes: Valley width (VW) = distance between first contour lines on either side of channel (1:24,000 scale USGS). Channel width (CW) = OHW channel width. Based on DNR (1994) Standard Watershed Analysis Methodology, six channel types with the potential for either lateral (bank erosion causing channel migration) and/or vertical (debris flow) scour potential were identified for streams being crossed by the pipeline. Of the 24 perennial/ ESA stream crossings, 11 possess some potential for vertical scouring or debris flow events, while 23 have at least some potential for lateral channel migration. Unconfined channels with slopes less than 1 percent (11 streams) are associated with: • Fine sediment deposition • Bank erosion • Wood accumulation Unconfined channels with slopes between 1 and 2 percent (3 streams) are associated with: • Wood loss • Scour potential • Fine sediment deposition • Bank erosion Unconfined channels with slopes between 2 and 4 percent (7 streams) are associated with: • Dam break flood • Debris flow deposition • Bank erosion • Coarse sediment deposition • Scour potential • Wood loss ES030613113935PDX 3 ---PAGE BREAK--- CHANNEL RESPONSE MATRIX FOR PIPELINE CROSSINGS OF PERENNIAL ENDANGERED SPECIES ACT STREAMS Unconfined channels with slopes between 4 and 8 percent (1 stream) are associated with: • Debris flow scour/debris flow deposition • Dam break flood • Wood loss Moderately confined channels with slopes less than 1 percent (1 stream) are associated with: • Fine sediment deposition • Bank erosion • Wood accumulation Confined channels with slopes less than 1 percent (1 stream) are associated with: • Coarse sediment deposition • Wood loss Ten of the evaluated waterways will be crossed via horizontal directional drilling (HDD). Of these 10 crossings, one (Bear Creek) has more than a slight vertical scour potential. Of the remaining nine HDD crossings, all have no vertical scour potential and have a slight lateral scour potential. The remaining crossing has a severe lateral scour potential (Bear Creek). This high-level method of scour potential determination relies exclusively on gradient, valley width, and channel width, excluding additional factors such as substrate type. For certain waterways, historical observation and empirical evidence suggest that the scour potential may be different than that estimated by this model. In these cases, engineering will determine the accurate depth for the pipe crossing. Conclusions Of the 24 perennial ESA streams being crossed by the pipeline, 11 have a slight or higher potential for vertical scouring. Of these, eight have a moderate or higher potential for vertical scouring. One channel has a severe potential for vertical scouring, and eight channels are mass-wasting dominated (MWD). The only stream with moderate/severe vertical scour potential is an intermediate waterway. Seven of the MWD streams are classified as intermediate, with the one remaining classified as minor. Thirteen streams have no vertical scour potential. Of the streams evaluated, five are considered major streams (100 feet or greater in width as defined by the Federal Energy Regulatory Commission’s Wetland and Waterbody Construction and Mitigation Procedures [2003]), none of which have a slight or higher potential for experiencing vertical scouring flows (no vertical scour potential). One crossing (Little Clatskanie River) has no or negligible potential for lateral channel migration (lateral scouring) at the reach scale, 13 have a slight potential, 3 have a moderate potential, and 7 have a severe potential for lateral channel migration. Of the seven streams with a severe potential for lateral scour, all are intermediate waterbodies. The five major stream crossings have a slight potential for lateral channel migration. Potential for vertical scour and channel migration will be used to inform engineers which streams require special attention regarding depth of pipeline during final design. Literature Cited Castro, J.M. 2009. Personal communications with Janine Castro, Ph.D. Geomorphologist, U.S. Fish and Wildlife Service, Portland, Oregon. April 9, 2009. Federal Energy Regulatory Commission. 2003. Wetland and Waterbody Construction and Mitigation Procedures. http://www.ferc.gov/industries/gas/enviro/guidelines.asp. January 17, 2003. Rosgen, D. 1996. Applied River Morphology. Wildland Hydrology, Pagosa Springs, Colorado. Washington Department of Natural Resources (DNR). 1994. Board Manual: Standard Methodology for Conducting Watershed Analysis Under Chapter 222-22 WAC. Washington Department of Natural Resources, Olympia, Washington. ES030613113935PDX 4 ---PAGE BREAK--- CHANNEL RESPONSE MATRIX FOR PIPELINE CROSSINGS OF PERENNIAL ENDANGERED SPECIES ACT STREAMS TABLE 2 Oregon Pipeline Crossings of Perennial ESA Streams Stream ID MP at Crossing Crossing Method Flow Regime Waterbody Type Waterbody Valley Width (ft)a OHW Width (ft) Channel Confinementb Gradient Vertical Scour Potentiald Lateral Channel Migration Potentiale S99CL001 1.0 HDD Perennial Major Adairs Slough 5,258 110 Unconfined <1 None Slight S5BCLo74 1.5 HDD Perennial Intermediate Vera Creek 4,960 20 Unconfined <1 None Slight S40CL002 3.1 HDD Perennial Major Lewis and Clark River 5,808 1250 Unconfined <1 None Slight S5BCL064 4.5 Dry/Flume Perennial Intermediate Barrett Slough 3,844 12 Unconfined <1 None Slight S99CL064 5.7 HDD Perennial Major Lewis and Clark River 2,261 340 Unconfined <1 None Slight S1BCL001 7.9 Dry/Flume Perennial Intermediate Heckard Creek 1,139 10 Unconfined <1 None Slight S99CL018 11.0 HDD Perennial Intermediate Lewis and Clark River 1,365 35 Unconfined <1 None Slight S2BCL008A 25.4 Dry/Flume Perennial Intermediate Little Fishhawk Creek 104 15 Unconfined <1 None Slight S2BCL008B 31.4 Open cut Perennial Intermediate Alder Creek 421 15 Unconfined 3.6 Moderate Severe S99CL108 33.5 HDD Perennial Major Nehalem River 3,601 120 Moderately Confined <1 None Slight S8BCL005 41.0 Open cut Perennial Intermediate Rock Creek 470 20 Unconfined 2.2 Moderate Severe S1BCL021 43.1 Dry/Flume Perennial Intermediate South fork Rock Creek 2,302 15 Unconfined 3.0 Moderate Severe S1BCL022 43.4 HDD Perennial Intermediate Bear Creek 436 12 Unconfined 2.3 Moderate Severe S6BCO002 47.5 Dry/Flume Perennial Intermediate North Fork Wolf Creek 143 30 Unconfined 1.0 Slight Moderate S3BCO012 50.5 Dry/Flume Perennial Intermediate Clear Creek 780 30 Unconfined 2.1 Moderate Severe S3BCO107 55.7 Dry/Flume Perennial Intermediate Cedar Creek 976 10 Unconfined 1.6 Slight Moderate S3BCO101 57.7 HDD Perennial Intermediate Rock Creek 1,157 30 Unconfined <1 None Slight S3BCO014 63.8 HDD Perennial Intermediate Nehalem River 113 30 Moderately Confined <1 None Slight S99CO020 70.7 Open cut Perennial Intermediate Clatskanie River 219 19 Unconfined <1 None Slight S5BCO001 71.8 Open cut Perennial Minor Little Clatskanie River 244 2 Unconfined 4 Moderate/Severe None S3BCO010 73.0 Open cut Perennial Intermediate Milton Creek 317 12 Unconfined 3.2 Moderate Severe S3BCO018 76.4 Open cut Perennial Minor Merril Creek 376 1 Unconfined 1.1 Slight Moderate S99CO011 81.6 Open cut Perennial Intermediate Deer Island Slough 780 38 Unconfined 2.1 Moderate Severe S99BCO014 82.4 HDD Perennial Major Columbia River 5,637 3300 Confined <1 None Slight a Valley width (VW) = distance between first contour lines on either side of channel (1:24,000 scale U.S. Geological Survey). b Channel confinement based on Channel Response Matrix (Table E-2) in DNR (1994): VW > 4CW = Unconfined 2CW < VW < 4CW = Moderately Confined VW < 2CW = Confined c Where gradient not field collected, used 1:24,000 USGS topographic maps. Gradient listed as 0.0% means gradient < d For vertical scour potential, “None” means on a reach scale. There will still likely be pool scour etc. e Lateral channel migration potential based on DNR (1994): ES030613113935PDX 5 ---PAGE BREAK--- CHANNEL RESPONSE MATRIX FOR PIPELINE CROSSINGS OF PERENNIAL ENDANGERED SPECIES ACT STREAMS TABLE 2 Oregon Pipeline Crossings of Perennial ESA Streams Stream ID MP at Crossing Crossing Method Flow Regime Waterbody Type Waterbody Valley Width (ft)a OHW Width (ft) Channel Confinementb Gradient Vertical Scour Potentiald Lateral Channel Migration Potentiale None = Could be microbank erosion but not lateral channel migration. Slight = Unconfined or moderately confined channel with gradient < Moderate = Unconfined or moderately confined channel with gradient 1% - Severe = Unconfined or moderately confined channel with gradient 2% - Stream ID = stream identification number ft = feet MP = milepost ES030613113935PDX 6 ---PAGE BREAK--- APPENDIX G5 RIPARIAN AREAS CROSSED BY THE OREGON LNG PIPELINE ---PAGE BREAK--- ---PAGE BREAK--- G5-1 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 1 S99CL001 110 Adairs Slough HDD Perennial 0.00 2 PEM2, PSS2, ST2 88 PSS2 400 1.5 S5BCL074 20 Vera Creek Flume Perennial 0.49 2 PEM2, PEM3, PSS2, PSS3, ST2 18 PSS2; 7 PSS3 400 2.6 S40CL001 50 Tributary of Lewis and Clark River Open Cut Intermittent 0.47 3 PSS2, ST3 87 PSS2 200 3.1 S40CL002 1250 Lewis and Clark River HDD Perennial 0.00 2 ST2 400 3.5 S99CL019 13 Tributary of Jeffers Slough Flume Perennial 0.23 3 PEM5, ST3 400 4.1 S5BCL059 1.5 Tributary of Barrett Slough Flume Perennial 0.10 3 PEM5, ST3 400 4.2 S5BCL062 2 Tributary of Barrett Slough Open Cut Intermittent 0.12 3 PEM5, ST3 200 4.3 S5BCL063 4.5 Tributary of Barrett Slough Open Cut Intermittent 0.06 3 PEM5, ST3 200 4.5 S5BCL064 12 Barrett Slough Flume Perennial 0.00 2 DF4, PEM2, PEM5, PFO2, ST2 5 DF4, 0 PFO2 400 4.6 S5BCL066 3 Tributary of Barrett Slough Open Cut Intermittent 0.11 3 BP6, PEM2, PEM5, ST3 200 4.8 S5BCL068 8 Tributary of Green Slough Open Cut Intermittent 0.30 3 PEM3, PEM5, ST3 200 4.8 S5BCL069 7 Tributary of Green Slough Open Cut Intermittent 0.40 3 PEM3, PEM5, ST3 200 4.9 SBCL070 2 Unnamed Open Cut Intermittent 0.20 2 AW5, DF4, ST2 4 DF4 0 5 S5BCL071 5 Unnamed HDD Intermittent 0.54 3 DF4, PEM5, PFO2, ST3 11 DF4, 30 PFO2 200 5.2 S5BCL072 7 Tributary of Lewis and Clark River HDD Perennial 0.09 2 DF4, PEM2, PEM5, PFO2, PSS2, ST2 55 DF4, 4 PFO2, 0 PSS2 400 5.2 S99CL111 300 Lewis and Clark River HDD Perennial 0.00 2 BP5, DF4, PEM2, PEM5, PSS2, ST2 31 DF4, 0 PSS2 400 5.4 S99CL034 20 Tributary of Lewis and Clark River HDD Perennial 0.08 2 BP5, PEM2, PEM5, ST2 400 5.5 S99CL024 13 Tributary of Lewis and Clark River Open Cut Intermittent 0.10 2 PEM5, ST2 200 5.7 S99CL064 340 Lewis and Clark River HDD Perennial 0.00 2 NO4, PEM2, PEM3, PEM5, ST2 400 5.8 S38CL003 8 Tributary of Lewis and Clark River HDD Intermittent 0.41 3 PEM2, PEM3, PEM5, PSS2, ST3 11 PSS2 200 ---PAGE BREAK--- G5-2 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 7.9 S1BCL001 10 Heckard Creek Flume Perennial 0.02 2 CF4, PEM2, PEM3, PFO2, ST2 72 CF4, 17 PFO2 400 8.1 S1BCL050 10 Unnamed Open Cut Intermittent 0.13 3 CF4, CF5, PEM3 68 CF4, 30 CF5, 2 PEM3 200 8.6 S1BCL002 4 Tributary of Lewis and Clark River Open Cut Intermittent 1.17 2 CF4, ST2 99 CF4 200 8.8 S1BCL018 25 Tributary of Lewis and Clark River Flume Perennial 1.29 2 CF4, PEM2, ST2 95 CF4 400 9.1 S1BCL003 3 Tributary of Lewis and Clark River Open Cut Intermittent 0.86 2 CF4, ST2 99 CF4 200 9.3 S1BCL004 4 Tributary of Lewis and Clark River Open Cut Intermittent 0.82 3 CF5, ST3 99 CF5 200 9.7 S1BCL005 8 Tributary of Lewis and Clark River Open Cut Intermittent 0.97 2 CF4, CF5, ST2 88 CF4, 9 CF5 200 9.7 S1BCL006 3 Tributary of Lewis and Clark River Open Cut Intermittent 0.96 2 CF4, ST2 99 CF4 200 9.9 S1BCL007 3 Tributary of Lewis and Clark River Open Cut Intermittent 0.97 2 CF4, ST2 99 CF4 200 10 S1BCL008 10 Tributary of Lewis and Clark River Flume Perennial 0.98 2 CF4, ST2 99 CF4 400 11 S99CL018 35 Lewis and Clark River HDD Perennial 0.00 2 BP6, CF3, NO5, PEM2, PEM5, PFO2, ST2 6 CF3, 41 PFO2 400 12.8 S1BCL016 8 Tributary of Speelyai Creek Flume Perennial 1.03 2 CF4, ST2 99 CF4 400 13.8 S5BCL040 0.8 Tributary of Youngs River Flume Perennial 2.02 2 BP5, CF4, ST2 99 CF4 400 13.8 S5BCL041 2 Tributary of Youngs River Flume Perennial 2.03 2 BP5, CF4, ST2 99 CF4 400 13.9 S5BCL042 5 Tributary of Youngs River Open Cut Intermittent 2.05 2 CF4, ST2 98 CF4 200 13.9 S5BCL043 20 Tributary of Youngs River Open Cut Intermittent 2.08 2 CF4, ST2 95 CF4 200 14.1 S5BCL045 8 Tributary of Youngs River Flume Perennial 2.15 2 CF4, ST2 99 CF4 400 14.2 S5BCL044 5 Tributary of Youngs River Flume Perennial 2.16 2 CF4, ST2 99 CF4 400 14.8 S5BCL038 2 Tributary of Youngs River Open Cut Intermittent 2.28 2 CF4, DF4, ST2 84 CF4, 15 DF4 200 ---PAGE BREAK--- G5-3 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 15.3 S5BCL035 3 Tributary of Youngs River Open Cut Intermittent 2.09 2 CF4, CF5, ST2 0 CF4, 99 CF5 200 15.6 S5BCL030 4 Tributary of Youngs River Flume Perennial 2.11 2 CF4, CF5, ST2 77 CF4, 22 CF5 400 15.6 S5BCL034 4 Tributary of Youngs River Flume Perennial 2.08 2 CF4, CF5, ST2 58 CF4, 41 CF5 400 15.8 S5BCL031 5 Tributary of Youngs River Flume Perennial 2.25 2 CF4, DF3, DF4, PEM2, PEM3, ST2 11 CF4, 5 DF3, 72 DF4 400 16.1 S99CL016 7 Bayney Creek Flume Perennial 2.49 3 DF3, ST3 99 DF3 400 16.6 S5BCL032 3 Tributary of Youngs River Open Cut Intermittent 2.98 2 CF4, DF3, PEM3, ST2 96 CF4, 3 DF3 200 17.3 S5BCL077 6 Tributary of Youngs River Flume Perennial 3.61 2 CF4, ST2 99 CF4 400 17.8 S5BCL078 6 Tributary of Youngs River Open Cut Intermittent 4.05 2 DF3, PEM2, ST2 95 DF3 200 17.8 S5BCL079 5 Tributary of Youngs River Open Cut Intermittent 4.09 2 DF3, PEM2, ST2 90 DF3 200 17.9 S5BCL080 4 Tributary of Youngs River Open Cut Intermittent 4.20 2 DF3, ST2 99 DF3 200 18.4 S5BCL076 4 Tributary of Rock Creek Flume Perennial 4.64 3 CF4, DF4, PEM2, ST3 78 CF4, 20 DF4 400 18.5 S1BCL009 10 Rock Creek Flume Perennial 4.78 3 CF4, DF3, DF4, PFO2, ST2, ST3 15 CF4, 35 DF3, 35 DF4, 14 PFO2 400 18.8 S1BCL010 5 Tributary of Youngs River Open Cut Intermittent 5.08 2 CF4, DF3, ST2 82 CF4, 16 DF3 200 19 S1BCL011 6 Tributary of Youngs River Flume Perennial 5.25 2 DF3, PEM3, PFO2, PFO3, ST2 97 DF3, 0 PFO2, 1 PFO3 400 19.14 S1BCO012 3 Unnamed Open Cut Intermittent 2.93 2 DF3, ST2 99 DF3 200 19.3 S1BCL014 8 Osgood Creek Flume Perennial 5.55 3 CF3, CF4, CF5, DF3, PEM2, PEM3, PFO2, ST3 30 CF3, 33 CF4, 14 CF5, 15 DF3, 0 PFO2 400 19.6 S2BCL013A 7 Tributary of Osgood Creek Flume Perennial 5.79 3 CF3, CF4, PEM3, PFO2, ST3 13 CF3, 64 CF4, 14 PFO2 400 20.1 S2BCL013B 35 Fox Creek Flume Perennial 6.10 3 CF4, DF3, ST3 71 CF4 400 21.4 S38CL013 3 South Fork Youngs River Flume Perennial 7.16 2 CF4, DF3, ST2 71 CF4 400 21.6 S42CL003 3 Unnamed Open Cut Intermittent 2.83 2 CF4, DF3, ST2 81 CF4 200 21.8 S5BCL058 15 Tributary of Youngs River Flume Perennial 7.58 2 CF3, CF4, ST2 16 CF3 400 ---PAGE BREAK--- G5-4 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 22.1 S5BCL049 2.5 Tributary of Youngs River Flume Perennial 7.85 3 CF4, DF3, PEM2, ST2, ST3 95 CF4 400 22.2 S5BCL048 5 Tributary of Youngs River Open Cut Intermittent 7.92 3 CF4, DF3, ST3 98 CF4 200 22.5 S6BCL016 2 Tributary of Youngs River Open Cut Intermittent 8.20 2 CF4, DF3, PEM2, PFO2, ST2 20 CF4, 63 DF3, 10 PFO2 200 22.6 S6BCL013 1 Tributary of Youngs River Open Cut Intermittent 8.28 2 CF4, DF3, PEM2, ST2 88 CF4 200 22.6 S6BCL014 4 Tributary of Youngs River Open Cut Intermittent 8.29 2 CF4, DF3, ST2 96 CF4 200 22.6 S6BCL015 2 Tributary of Youngs River Open Cut Intermittent 8.23 2 CF4, DF3, PEM2, PFO2, ST2 36 CF4, 44 DF3, 12 PFO2 200 22.8 S6BCL010 2 Tributary of Youngs River Open Cut Intermittent 8.49 2 CF4, ST2 98 CF4 200 22.8 S6BCL011 2 Tributary of Youngs River Open Cut Intermittent 8.45 2 CF4, ST2 99 CF4 200 22.8 S6BCL017 3.5 Tributary of Youngs River Open Cut Intermittent 8.51 2 CF4, ST2 99 CF4 200 22.9 S6BCL018 4 Tributary of Fall Creek Open Cut Intermittent 8.62 3 CF4, ST3 99 CF4 200 23 S6BCL019 20 Tributary of Fall Creek Flume Perennial 8.66 3 CF3, CF4, ST3 54 CF3, 43 CF4 400 23.1 S6BCL020 3 Tributary of Fall Creek Open Cut Intermittent 8.77 3 CF3, ST3 99 CF3 200 23.4 S38CL014 10 Fall Creek Flume Perennial 9.11 3 CF3, CF4, DF3, ST3 40 CF3, 42 CF4, 14 DF3 400 24.3 S5BCL016 3.5 Tributary of Fishhawk Creek Open Cut Intermittent 2.36 3 CF4, ST3 99 CF4 200 24.4 S5BCL017 3.5 Tributary of Fishhawk Creek Open Cut Intermittent 2.34 3 CF4, PEM2, ST3 94 CF4, 4 PEM2 200 24.4 S5BCL018 6 Tributary of Fishhawk Creek Flume Perennial 2.32 3 CF4, PEM2, ST3 98 CF4, 1 PEM2 400 24.8 S2BCL001 7 Tributary of Fishhawk Creek Open Cut Intermittent 2.09 3 CF4, PSS2, ST3 82 CF4, 11 PSS2 200 24.8 S2BCL002 25 Tributary of Fishhawk Creek Open Cut Intermittent 2.08 3 CF4, PSS2, ST3 84 CF4, 9 PSS2 200 25.1 S2BCL003 8 Tributary of Fishhawk Creek Open Cut Intermittent 1.97 3 CF4, ST3 97 CF4 200 ---PAGE BREAK--- G5-5 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 25.2 S2BCL004 3 Tributary of Fishhawk Creek Open Cut Intermittent 1.96 3 CF4, ST3 96 CF4 200 25.2 S2BCL005 10 Tributary of Fishhawk Creek Flume Perennial 1.96 3 CF4, PEM2, ST3 97 CF4, 1 PEM2 400 25.3 S2BCL007 3 Tributary of Fishhawk Creek Flume Perennial 1.95 3 CF3, CF4, PEM2, ST3 10 CF3, 88 CF4, 0 PEM2 400 25.4 S2BCL008A 15 Tributary of Fishhawk Creek Flume Perennial 1.95 3 CF3, CF4, PEM2, ST3 10 CF3, 88 CF4, 0 PEM2 400 25.7 S2BCL009 10 Tributary of Little Fishhawk Creek Flume Perennial 4.29 3 CF4, DF3, ST3 80 CF4, 18 DF3 400 25.7 S2BCL010 4 Tributary of Little Fishhawk Creek Open Cut Intermittent 4.27 3 CF4, ST3 98 CF4 200 25.9 S2BCL012 10 Tributary of Little Fishhawk Creek Open Cut Intermittent 4.19 3 CF4, PEM2, ST3 94 CF4 200 26.3 S5BCL019 1.2 Tributary of Little Fishhawk Creek Flume Perennial 3.87 2 CF4, ST2 100 CF4 400 26.5 S5BCL029 1.5 Tributary of Little Fishhawk Creek Flume Perennial 3.68 2 CF4, ST2 99 CF4 400 26.6 S5BCL027 1 Tributary of Little Fishhawk Creek Flume Perennial 3.63 2 CF4, ST2 99 CF4 400 26.6 S5BCL028 2 Tributary of Little Fishhawk Creek Open Cut Intermittent 3.63 2 CF4, ST2 99 CF4 200 26.8 S5BCL023 1.3 Tributary of Little Fishhawk Creek Flume Perennial 3.40 3 CF3, CF4, PEM2, ST3 61 CF3, 38 CF4 400 26.8 S5BCL025 1.4 Tributary of Little Fishhawk Creek Flume Perennial 3.41 3 CF3, CF4, PEM2, ST3 48 CF3, 51 CF4 400 27 S5BCL022 3 Tributary of Little Fishhawk Creek Open Cut Intermittent 3.27 3 CF3, CF4, ST3 50 CF3, 50 CF4 200 27.2 S5BCL021 6 Tributary of Little Fishhawk Creek Flume Perennial 3.05 3 CF3, CF4, PEM2, ST3 19 CF3, 79 CF4 400 27.3 S5BCL020 1.8 Tributary of Little Fishhawk Creek Flume Perennial 2.97 3 CF3, CF4, CF5, PEM2, ST3 18 CF3, 81 CF4, 1 CF5 400 27.4 S5BCL015 4 Tributary of Little Fishhawk Creek Flume Perennial 2.89 3 CF4, CF5, ST3 99 CF4, 1 CF5 400 27.6 S5BCL014 2.4 Tributary of Little Fishhawk Creek Open Cut Intermittent 2.68 3 CF4, ST3 99 CF4 200 27.8 S5BCL012 2 Tributary of Little Fishhawk Creek Open Cut Intermittent 2.55 3 CF3, CF4, ST3 11 CF3, 87 CF4 200 ---PAGE BREAK--- G5-6 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 27.8 S5BCL013 2 Tributary of Little Fishhawk Creek Open Cut Intermittent 2.56 3 CF3, CF4, ST3 12 CF3, 87 CF4 200 27.9 S5BCL011 3 Tributary of Little Fishhawk Creek Open Cut Intermittent 2.46 3 CF4, CF5, ST3 49 CF4, 50 CF5 200 28.1 S5BCL010 3.5 Tributary of Little Fishhawk Creek Flume Perennial 2.35 3 CF4, CF5, ST3 4 CF4, 96 CF5 400 28.4 S5BCL007 6 Tributary of East Humbug Creek Open Cut Intermittent 1.24 3 CF4, ST3 98 CF4 200 28.5 S5BCL004 7 Tributary of East Humbug Creek Open Cut Intermittent 1.13 3 CF4, ST3 98 CF4 200 28.5 S5BCL005 4 Tributary of East Humbug Creek Open Cut Intermittent 1.19 3 CF4, ST3 99 CF4 200 29 S5BCL001 3 Tributary of East Humbug Creek Open Cut Intermittent 0.79 3 CF4, ST3 97 CF4 200 29 S5BCL002 2 Tributary of East Humbug Creek Open Cut Intermittent 0.81 3 CF4, DF3, ST3 73 CF4, 25 DF3 200 29.4 S6BCL007 1 Tributary of East Humbug Creek Open Cut Intermittent 0.81 3 CF3, CF4, ST3 2 CF3, 98 CF4 200 29.4 S6BCL008 1.5 Tributary of East Humbug Creek Open Cut Intermittent 0.80 3 CF3, CF4, ST3 1 CF3, 98 CF4 200 29.5 S6BCL005 6 Tributary of East Humbug Creek Flume Perennial 0.78 3 CF4, ST3 98 CF4 400 29.5 S6BCL006 7 Tributary of East Humbug Creek Flume Perennial 0.79 3 CF3, CF4, ST3 1 CF3, 98 CF4 400 29.9 S6BCL004 5 Tributary of East Humbug Creek Open Cut Intermittent 0.59 3 CF3, CF4, ST3 15 CF3, 84 CF4 200 30.9 S2BCL021 2 Tributary of East Humbug Creek Open Cut Intermittent 0.72 3 CF4, ST3 99 CF4 200 31.4 S2BCL008B 15 Alder Creek Flume Perennial 0.00 2 CF3, CF4, PEM2, PEM3, ST2 32 CF3, 63 CF4 400 31.6 S6BCL001 3.5 Tributary of Alder Creek Open Cut Intermittent 0.21 2 CF4, ST2 99 CF4 200 32 S3BCL001 6 Tributary of Nehalem River Open Cut Intermittent 0.69 2 CF3, CF4, ST2 3 CF3, 95 CF4 200 32 S3BCL002 6 Tributary of Nehalem River Open Cut Intermittent 0.68 3 CF3, CF4, ST2, ST3 24 CF3, 73 CF4 200 32.1 S3BCL003 4 Tributary of Nehalem River Open Cut Intermittent 0.67 3 CF3, CF4, ST2, ST3 25 CF3, 72 CF4 200 ---PAGE BREAK--- G5-7 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 32.1 S3BCL004 6 Tributary of Nehalem River Open Cut Intermittent 0.66 2 CF4, ST2 98 CF4 200 32.3 S3BCL005 8 Tributary of Nehalem River Open Cut Intermittent 0.67 3 CF3, CF4, ST3 68 CF3, 27 CF4 200 32.3 S3BCL006 10 Tributary of Nehalem River Open Cut Intermittent 0.67 3 CF3, CF4, ST3 74 CF3, 22 CF4 200 32.4 S3BCL007 8 Tributary of Nehalem River Open Cut Intermittent 0.68 3 CF3, CF4, ST3 83 CF3, 12 CF4 200 33.5 S99CL108 120 Nehalem River HDD Perennial 0.00 2 BP4, BP5, BP6, CF3, DF3, ST2 32 CF3, 37 DF3 400 34.4 S5BCL046 2 Tributary of Nehalem River Flume Perennial 1.06 2 CF4, PEM3, ST2 99 CF4 400 36.2 S3BCL101 10 Unnamed Flume Perennial 0.26 3 CF4, ST2, ST3 92 CF4 400 36.3 S3BCL102 5 Unnamed Flume Perennial 0.27 3 CF4, ST2, ST3 93 CF4 400 37.5 S8BCL004 5 Tributary of North Fork Quartz Creek Flume Perennial 0.47 3 CF3, CF4, PEM3, ST2, ST3 66 CF3, 2 CF4 400 37.7 S8BCL003 2.3 Tributary of North Fork Quartz Creek Open Cut Intermittent 0.54 3 CF4, PEM3, ST3 35 CF4 200 38.5 S8BCL001 2 Tributary of South Form Quartz Creek Flume Perennial 1.28 3 CF3, CF4, PSS3, ST2, ST3 7 CF3, 87 CF4, 5 PSS3 400 39.6 S1BCL029 2.6 Tributary of Military Creek Open Cut Intermittent 0.28 3 CF3, CF4, PFO2, ST3 23 CF3, 38 CF4, 39 PFO2 200 39.8 S1BCL027 1.5 Tributary of Military Creek Open Cut Intermittent 0.17 3 BP4, CF3, CF4, ST3 1 BP4, 25 CF3, 73 CF4 200 39.8 S1BCL028 2.6 Tributary of Military Creek Open Cut Intermittent 0.18 3 BP4, CF4, ST3 2 BP4, 97 CF4 200 41 S8BCL005 20 Rock Creek HDD Perennial 0.00 2 CF4, DF3, PEM2, PFO2, PSS3, ST2 67 CF4, 10 DF3, 15 PFO2, 6 PSS3 400 42.3 S8BCL009 11 Tributary of South Fork Rock Creek Flume Perennial 0.00 2 CF4, CF5, DF3, DF4, PFO2, ST2 46 CF4, 7 CF5, 22 DF3, 4 DF4, 19 PFO2 400 42.7 S1BCL020 6 Tributary of South Fork Rock Creek Flume Perennial 0.03 2 CF4, DF3, ST2 77 CF4, 22 DF3 400 43.1 S1BCL021 15 South Fork Rock Creek HDD Perennial 0.00 2 CF3, CF4, DF3, PEM3, ST2 17 CF3, 66 CF4, 15 DF3 400 43.4 S1BCL022 12 Bear Creek HDD Perennial 0.00 2 BP6, CF3, DF3, PFO2, ST2 78 CF3, 8 DF3, 7 PFO2 400 ---PAGE BREAK--- G5-8 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 43.5 S1BCL023 1.3 Tributary of Bear Creek HDD Intermittent 0.04 2 BP6, CF3, PFO2, ST2 81 CF3, 7 PFO2 200 43.7 S1BCL024 1.6 Tributary of Bear Creek Flume Perennial 0.09 2 BP4, CF3, PEM3, ST2 95 CF3 400 43.9 S1BCL025 4 Tributary of Bear Creek Open Cut Intermittent 0.12 2 BP4, CF3, PEM3, ST2 71 CF3 200 44 S1BCL026 3 Tributary of Bear Creek Open Cut Intermittent 0.11 2 BP4, CF3, PEM3, ST2 92 CF3 200 44.2 S1BTI001 6 Bear Creek Flume Perennial 0.18 2 BP4, CF3, PFO2, ST2 82 CF3, 5 PFO2 400 44.3 S1BTI002 1.8 Tributary of Bear Creek Open Cut Intermittent 0.27 3 BP4, CF3, PEM3, ST3 79 CF3 200 44.8 S5BTI001 8 Tributary of Wolf Creek Flume Perennial 2.70 3 CF3, PEM2, ST3 99 CF3 400 45.1 S1BTI003 4 Tributary of Wolf Creek Open Cut Intermittent 2.41 3 CF3, ST3 99 CF3 200 47.62 S6BCO002 30 North Fork Wolf Creek Flume Perennial 0.00 2 CF3, ST2 97 CF3 400 48.3 S1BCO000 3 Tributary of North Fork Wolf Creek Flume Perennial 0.64 3 BP5, CF4, CF5, PEM3, ST3 37 CF4, 55 CF5 400 50.5 S3BCO012 30 Clear Creek Flume Perennial 0.03 2 BP3, CF4, CF5, DF3, ST2 32 CF4, 42 CF5, 20 DF3 400 53.6 S3BCO002 1 Fall Creek Flume Perennial 2.28 2 BP4, CF3, CF4, PEM3, ST2 70 CF3, 25 CF4 400 55.7 S3BCO107 10 Cedar Creek Flume Perennial 0.01 2 CF3, CF4, PEM3, ST2 24 CF3, 45 CF4 400 55.8 S3BCO106 4 Tributary of Cedar Creek Flume Perennial 0.21 2 BP5, CF3, CF4, CF5, PEM3, ST2 11 CF3, 1 CF4, 58 CF5 400 57.7 S3BCO100 10 Tributary of Rock Creek HDD Perennial 0.01 2 BP5, CF4, CF5, ST2 22 CF4, 66 CF5 400 57.7 S3BCO101 30 Rock Creek HDD Perennial 0.00 2 CF5, ST2 92 CF5, 8 ST2 400 57.7 S3BCO101B 10 Braided Channel to Rock Creek HDD Perennial 0.00 2 CF5, ST2 87 CF5, 13 ST2 400 63.8 S3BCO014 30 Nehalem River HDD Perennial 0.00 2 BP6, CF4, DF3, ST2 77 CF4, 13 DF3 400 66.3 S3BCO103 1 Tributary of Oak Ranch Creek Open Cut Intermittent 0.68 3 BP5, CF5, PEM3, ST3 91 CF5 200 67.7 S6BCO004 3 Unnamed Open Cut Intermittent 0.38 3 CF3, CF4, ST3 2 CF3, 98 CF4 200 68 S6BCO003 3 Unnamed Flume Perennial 0.49 3 CF4, ST3 100 CF4 400 70.2 S3BCO003 1 Tributary of Clatskanie River Flume Perennial 0.59 2 CF4, PEM3, ST2 99 CF4 400 ---PAGE BREAK--- G5-9 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 70.7 S99CO020 18.5 Clatskanie River Flume Perennial 0.00 2 BP6, CF3, CF4, CF5, ST2 39 CF3, 25 CF4, 32 CF5 400 71 S99CO021 1 Unnamed Flume Perennial 0.19 3 CF4, PEM3, ST3 99 CF4 400 71.8 S5BCO001 2 Little Clatskanie River Flume Perennial 0.06 2 CF3, CF4, ST2 49 CF3, 51 CF4 400 72.7 S3BCO008 2 Tributary of Milton Creek Flume Perennial/ Intermittent 0.24 2 CF3, ST2 100 CF3 400 73 S3BCO010 12 Milton Creek Flume Perennial 0.02 2 CF4, DF3, PEM/PSS/PFO3, ST2 36 CF4, 12 DF3, 50 PEM/PSS/PFO3 400 73.5 S1BCO004 3 Apilton Creek Open Cut Intermittent 0.54 3 CF3, CF4, PSS/PFO3, ST3 23 CF3, 66 CF4, 10 PSS/PFO3 200 73.6 S1BCO005 1 Tributary of Apilton Creek Open Cut Intermittent 0.58 3 CF3, PEM3, ST3 76 CF3 200 74.5 S5BCO011 5 Unnamed Flume Perennial 0.12 2 CF4, DF3, PFO3, ST2 58 CF4, 36 DF3, 2 PFO3 400 74.6 S5BCO010 30 Unnamed Flume Perennial 0.12 2 CF3, CF4, DF3, PFO3, ST2 20 CF3, 34 CF4, 40 DF3, 2 PFO3 400 74.9 S6BCO001 22 Milton Creek Flume Perennial 0.00 2 CF4, CF5, DF3, PFO3, ST2 65 CF4, 21 CF5, 10 DF3, 1 PFO3 400 76.3 S3BCO110 1 Tributary of Merrill Creek Open Cut Intermittent 0.24 2 CF3, ST2 100 CF3 200 76.4 S3BCO017 35 Merrill Creek Flume Perennial 0.00 3 CF3, CF4, PEM/PFO3 1 CF3, 92 CF4, 7 PEM/PFO3 400 78.2 S2BCO009 3 Tributary of Merrill Creek Open Cut Intermittent 0.38 2 CF3, ST2 99 CF3 200 78.4 S3BCO122 10 Tributary of Merrill Creek Flume Perennial 0.20 2 CF3, CF4, PSS/PFO3, ST2 43 CF3, 56 CF4, 1 PSS/PFO3 400 79 S3BCO119 1 Tributary of Merrill Creek Open Cut Intermittent 0.92 2 CF3, PEM3, ST2 69 CF3 200 79 S3BCO120 1 Tributary of Merrill Creek Open Cut Intermittent 0.87 2 CF3, PEM3, ST2 58 CF3 200 79.9 S3BCO115 1 Tributary of Merrill Creek Flume Perennial 2.01 2 CF3, DF3, PEM3, ST2 45 CF3, 50 DF3 400 81.6 S99CO011 280 Deer Island Slough Flume Perenniall 0.46 2 PEM, PFO, ST 63 PFO 400 82 S3BCO123 20 Dyna Nobel Channel HDD Perennial 0.45 2 BP, NO, PEM, PFO, PSS, ST 21 PFO, 5 PSS 400 82.3 S99CO014 3300 Columbia River HDD Perennial 0.00 2 BP, NO, PEM, ST 400 83.3 S99CW020 10 Burris Creek Flume Perennial 0.00 NO 400 85.8 S99CW021 2 Unnamed Flume Perennial 0.36 PEM 400 ---PAGE BREAK--- G5-10 Appendix G5 Riparian Areas Crossed by the Oregon LNG Pipeline Milepost Stream ID a Stream Width b Waterbody c Crossing Method d Stream Type Miles to Salmonid Habitat ODFW Stream Type ODFW Habitat Type e Riparian Cover f Approximate Width of Riparian Area Per Side g (feet) 86 S99CW022 2 Unnamed Flume Perennial 0.31 BP, NO, PEM 400 86.5 S99CW023 3 Unnamed Open Cut Intermittent 0.48 DF, MO, PEM 10 DF 200 86.7 S99CW025 3 Unnamed Open Cut Intermittent 0.40 BP, DF, PEM 48 DF 200 86.8 S99CW026 3 Unnamed Flume Perennial 0.39 BP, DF, PEM 65 DF 400 a Stream ID numbers beginning in S99 and S38 are for areas with no field access and are based on aerial photography and Pacific Northwest Hydrography Network database. Duplicate stream ID and milepost numbers may occur as a result of rounding of mileposts to the nearest tenth of a mile. b Widths in feet are stream ordinary high water mark. c Waterbody includes any natural or artificial stream, river, or drainage with perceptible flow at the time of crossing, and other permanent waterbodies. d Construction methods for crossing waterbodies are flume, HDD (horizontal directional drilling), or open-cut. e ODFW habitat types: BP = Buildings and developed land CF = Coniferous forest DF = Deciduous forest NO = Agricultural land PEM = Palustrine emergent wetland PFO = Palustrine Forest PSS = Palustrine scrub/shrub wetland ST = Stream f Riparian area = DF4, 3, 2; CF4, 3, 2; PFO; PSS. g Riparian area widths are for side of stream with maximum width. ---PAGE BREAK--- APPENDIX G6 LANDSLIDE AND DEBRIS FLOW RISK NEAR WATERBODY CROSSINGS ---PAGE BREAK--- ---PAGE BREAK--- 1 T E C H N I C A L M E M O R A N D U M Landslide and Debris Flow: Relative Risk Assessment for the Bidirectional Project Pipeline PREPARED FOR: Peter Hansen/Oregon Pipeline Company, LLC PREPARED BY: Todd Cotten/CH2M HILL DATE: November 15, 2013 PROJECT NUMBER: 199863.PT.07; 199863.PP.07 Introduction The purpose of this technical memorandum is to evaluate landslide and erosion hazards near 13 stream crossings selected along the proposed liquefied natural gas (LNG) pipeline (Pipeline) for the Bidirectional Project (Project). Two types of landslide hazards were evaluated: rotational slides and debris flows. Thirteen stream crossings along approximately 87 miles of the Pipeline between the Terminal near Warrenton, Oregon, and the interconnect with the existing Northwest Pipeline LLC (Northwest) pipeline near Woodland, Washington, were identified for this evaluation based on the following criteria: salmon habitat protected under the endangered species act (ESA) has been identified in the stream to be crossed, and the proposed Pipeline construction method consists of traditional cut‐and‐cover in conjunction with fluming of the stream at the crossing. Other ESA‐listed streams will be crossed using horizontal directional drilling (HDD) or other trenchless installation techniques. Trenchless installation methods have less impact in the immediate vicinity of stream crossings because the primary work areas at the entry and exit locations are typically at least 700 feet away from the stream and very little disturbance occurs between these work areas. In addition, the Pipeline will be installed at much greater depths below the stream when installed using HDD or other trenchless methods. ESA stream crossings where trenchless installation methods are proposed therefore are not discussed in this memorandum. The relative risk of two types of landslides hazards, rotational slides and debris flows/rapid erosion, were assessed for the stream crossings evaluated using a set of risk factors. The primary risk factor evaluated relates to the presence of landslide hazards that are shown on published geologic hazard mapping and on landslide inventory mapping developed for the Project. Where mapped landslides or debris flow/rapid erosion hazards are identified on landslide mapping, the type and location of hazard is summarized for each of the selected stream crossings. Additional risk factors are evaluated for each crossing location to determine a relative hazard score for each of the 13 stream crossings evaluated. The risk factors used in the assessment consisted of the following:  Slope Steepness  Landform  Geology  Land Use  Scour Potential  Channel Migration Table 1 lists the 13 stream crossings evaluated for landslide potential and the location, by milepost (MP), along the alignment. All 13 stream crossings evaluated are located in Oregon. The first 3 stream crossings listed are in Clatsop County and the remaining 10 are in Columbia County. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 2 TABLE 1 Stream Crossing Summary Waterbody Stream ID Milepost (approximate) Barrett Slough S5BCL064 4.4 Heckard Creek S1BCL001 7.9 Alder Creek S2BCL008B 31.4 North Fork Wolf Creek S6BCO002 47.6 Clear Creek S3BCO012 50.5 Cedar Creek S3BCO107 55.7 Clatskanie River S99CO020 70.7 Little Clatskanie River S5BCO001 71.8 Milton Creek S3BCO010 73.0 Milton Creek S6BCO001 74.9 Merrill Creek S3BCO017 76.4 Tributary of Merrill Creek S3BCO122 78.4 Deer Island Slough S99CO011 81.6 Note: Milepost refers to the approximate milepost along the Pipeline for the Oregon Pipeline Project. ID = identification This memorandum is organized into the following sections: Landslide Risk Factors, Stream Crossings, Summary of Landslide Risk Assessment, Limitations, and References. Landslide Risk Factors Landslides can have multiple causes. This section examines the physical, geological, and human‐made causes of landslides and the risk factors that contribute to landslide potential. The following risk factors are addressed: mapped landslide hazard, slope steepness, landform, geology, land use, scour potential, and channel migration. A scoring system for each risk factor was developed in order to determine the relative landslide hazard for each of the 13 stream crossings. Mapped Landslide Hazard The most critical risk factor affecting the potential for future landslides is judged to be the presence of existing landslide features in the immediate vicinity of the stream crossings evaluated. The presence of mapped landslide features is critical because hill slope areas that have failed in the past often remain in a weakened state, and may tend to fail repeatedly over time. Additionally, large landslide complexes may have moved several times over thousands of years, with long periods of stability punctuated by episodes of movement. Thus, previously failed areas are particularly important to identify because they may be susceptible to future instability. Two general types of landslide mapping were evaluated: published geologic mapping and landslide hazard inventory mapping developed specifically for the Project. Published Hazard Mapping In addition to using the landslide hazard inventory mapping developed for the Project, the potential for landslide hazards to be present in the vicinity of each of the 13 stream crossings has been evaluated by reviewing published geologic and landslide hazard reports. Some of these reports focus on identifying ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 3 documented historical landslides, others focus on identifying landslide topography, and a third group focus on identifying potential landslide areas. The following four primary sources of landslide hazard information, published by the Department of Geology and Mineral Industries (DOGAMI), have been used to identify the potential hazards for slope instability at each stream crossing:  Statewide Landslide Information Database for Oregon (SLIDO‐2)  Slope Failures in Oregon: GIS Inventory for Three 1996/97 Storm Events; Oregon Department of Geology and Mineral Industries, Special Paper 34 (Hofmeister, 2000)  “Potential Rapidly Moving Landslide Hazards in Western Oregon” (IMS‐22) (Hofmeister, 2002) Numerous additional geologic and hazard maps produced by DOGAMI were reviewed to identify potential landslide hazards at the stream crossings. These maps typically identify the locations of active landslides, inactive landslides, and landslide debris. The following maps from DOGAMI Bulletin 79, Environmental Geology of Inland Tillamook and Clatsop Counties, Oregon, were included in this review:  Hazard Map of the Birkenfeld Quadrangle (Beaulieu, 1972a)  Hazard Map of the Saddle Mountain Quadrangle (Beaulieu, 1972b) Project-Specific Landslide Hazard Inventory Mapping A landslide deposit inventory map has been developed for the Project. Landslide inventory maps typically show the locations of identified historic and prehistoric landslide deposits for an area along with the characteristics of each landslide. Landslide inventory maps provide basic information for identifying areas of higher and lower hazards, and landslide susceptibility, which is the first step in risk reduction. Although areas with mapped landslide deposits are likely to be at higher risk than other areas, these areas will not automatically experience problems in the future. However, hill slope areas that have failed in the past often remain in a weakened state, and may tend to fail repeatedly over time. Large landslide complexes may have moved several times over thousands of years, with long periods of stability punctuated by episodes of movement. Thus, previously failed areas are particularly important to identify because they may be susceptible to future instability. Landslide and mass‐movement topography, recent landslides, and areas that appear to be susceptible to gullying or rapid erosion were mapped on 1:24,000‐scale, color stereo‐pairs of aerial photographs. For the portion of the Project between MP 0.0 and approximately MP 47.5, the aerial photographs utilized were taken in June 2007 by i‐TEN Associates of Portland, Oregon, and the mapping developed in 2009 (CH2M HILL, 2009). These aerial photographs provide coverage within Clatsop and Tillamook counties, Oregon. In Columbia County, Oregon, and Cowlitz County, Washington, from approximately MP 47.5 to the end of the Pipeline near MP 87.8, mapping was conducted using 1:13,560 scale aerial photographs taken in September 2011 by Continental Mapping Consultants, Inc., and the mapping developed in 2011 (CH2M HILL, 2011). Figures 1 through 18 in the Attachment to this memorandum show the combined 2009 and 2011 landslide inventory and geologic hazard maps developed for the Project. In addition, light detection and ranging (LIDAR) data of the alignment are available to assist in delineating landslide areas in Columbia County. These data provide a detailed image of the ground surface and allow the identification of the topographic features associated with landslides. According to Burns and Madin (2009), the use of LIDAR data resulted in identification of 3 to 200 times the number of landslide found with other data sets, and the accuracy of the spatial extent of the landslides identified was greatly improved with LIDAR data. Large areas of mass movement terrain were identified by the following features:  Steep, arcuate, curved headscarps (pull‐away zone) that form bowl‐shaped areas ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 4  Irregular, hummocky topography; disrupted or poorly developed drainage patterns and high drainage density; closed depressions and ponds within the slide mass; transverse ridges, and raised toes and lobes  Deep gullies eroded into the weak, disturbed soils and rock  Concave, nonplanar hillsides with steep upper slopes and flatter irregular lower slopes  Drainages blocked by slide toes and lobes that often result in low‐gradient streams that have areas of alluvium “ponded” behind them The general direction of landslide movement is shown by an arrow. Obvious younger headscarps and smaller scarps within the slide mass are delineated on the landslide inventory mapping. Scarps in thick trees are more difficult to identify, but often have semi‐circular logging roads following them around heads of drainages and are distinguished from shaped drainage heads. Large areas of “mass movement terrain” are delineated by a triangular stippled pattern (similar to mass movement terrain shown on previous published mapping by Beaulieu, 1973). The landslide masses are typically downslope from the arcuate headscarps, which are outlined on the maps. As landslides age and are subjected to erosion and weathering, the topographic features become more subdued and difficult to identify. Outlines of older landslides with a lower confidence of identification are shown by dashed outlines. The landslide inventory mapping also shows features such as rock quarries and areas of ponded stream alluvium. Generally, features such as hummocky topography, steep headscarps, gullies, ridges, and closed depressions were more easily observed in clearcut areas on the aerial photographs. Areas that appear to be more susceptible to rapid erosion and gullying were also delineated on the aerial photographs. These areas are where the proposed alignment crosses side slopes that exhibit debris flows and steep‐sided, deep erosional channels in weak soils. These areas are shown by an arrow. Often, in landslide areas, the erosional channels do not follow the “fall‐line” towing to diversion by the irregular slide mass (deviation from the expected drainage patterns). Steep‐sided gullies could be observed in the landslide mass, where the weakened, disturbed slide mass is more easily eroded. Slope angles are often considered in landslide susceptibility and general landslide hazard, particularly for the hazard of potentially rapid‐moving landslides. However, in the Project vicinity, the presence of large areas of landslide topography appears to be related more to lithology and areas of weak, interbedded sedimentary rocks rather than steeper slope angles. For example, stronger rocks such as basalt flows, intrusive basalts, and sandstones form steeper, more stable slopes that are not as susceptible to sliding. The steepest slopes along the Project are found in areas underlain by these types of rocks, and they actually exhibit fewer landslides despite being steeper. For example, between approximately MP 40 and 44, slopes are steep but fewer landslides were mapped because much of this area is underlain by sandstones (Sunset Highway member). In fact, Beaulieu (1973) notes that “slopes within the slide mass are gentler than those of the surrounding intact terrain.” Steep slopes thus do not necessarily equate to greater landslide hazard. Steep slopes are often underlain by harder rock, and are actually more stable. For example, in the Birkenfeld Quadrangle, many large areas of landslides form flatter terrain, especially where very old slide masses are highly eroded and exhibit subdued topography and low slope angles. Limitations of the Data and Landslide Inventory Mapping. Landslide inventory mapping is based on available aerial photographs and LIDAR data. Mapping is subject to interpretation or misinterpretation of the data, and landslides can be missed or overlooked. No field checking or verification of the mapping was conducted for Columbia County. Limited field checks were conducted for Clatsop County. Field checking tends to be time consuming and expensive and detailed geologic mapping is generally not completed as part of the Federal energy Regulatory Commission (FERC) permitting process. Limitations of the landslide inventory mapping include the following: ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 5  At this level of inventory mapping, landslides were not classified by type versus debris flow).  Features of older landslide deposits are more difficult to identify because of erosion and the tendency to be covered with younger deposits.  The ages of landslides were not estimated, and landslides were not assigned to historic and pre‐historic categories younger and older than 150 years). However, landslides with less‐recognizable features are generally interpreted to be older, and are delineated by dashed lines.  Landslides were not classified as “deep” or “shallow” and the depths of landslides were not estimated. However, where a larger, deeper slide mass was recognizable, the mass was shown by a triangular stippled pattern.  Landslide inventory/deposit mapping is NOT a map or complete inventory of locations of all past landslides.  Very small landslide deposits cannot always be identified because of the resolution of LIDAR data, scale of aerial photos, and forest cover. Also, some areas of landslide terrain extend over several square miles and extend beyond the mapping corridor.  The aerial photographs and LIDAR data are “snapshot” views of the existing landscape at the time of the photographs or generation of terrain model. New landslides may occur as the result of increased precipitation or changes in land use in the vicinity. Table 2 presents the scoring system used for the risk related to a mapped landslide hazard. Because the presence of mapped landslide hazard is judged to be the single most important factor in predicting the possibility of future landslide events, the scoring range for this criterion is set between zero and 10, where other factors have a range between 0 and six. The system was developed based on the relative distance of each stream crossing to the mapped hazard. A score of 0 represents the lowest relative hazard for a mapped landslide area and a score of 9 represents the highest relative hazard. TABLE 2 Mapped Landslide Hazard Scoring System Mapped Landslide Hazard Score No documented or mapped landslide hazard in the vicinity of the stream crossing 0 Mapped areas of low landslide hazard 2 Mapped areas of landslide topography or areas of moderate landslide hazard 5 Areas meeting one of the following conditions: 1. Steam crossing is in the immediate vicinity of potential Gullying/Rapid Erosion/or Debris Flow 2. Within mapped area of inferred landslide 3. Area shown as high landslide hazard 8 Adjacent to recent documented landslide or within mapped landslide area 10 Slope Steepness An important risk factor affecting the potential for landslides is slope steepness in the general vicinity of each of the 13 stream crossings evaluated. For this evaluation, slope refers to the steepness of the ground, or the height the slope rises in a given distance. For example, if the elevation difference between the toe of a slope and the crest of a slope is 50 feet and the horizontal distance between the toe and crest of the slope is 100 feet, an average slope geometry of 50 percent exists. As a general rule, the steeper the slope, the more susceptible it will be to landslides. This theory has been corroborated by a number of studies, including one study by the Oregon Department of Forestry (ODF), which found that all debris flows in the ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 6 study areas were initiated on slopes greater than 40 percent steepness and most landslides (86 percent) were initiated where slope steepness was measured to be over 70 percent (Robison et al., 1999). Various land survey studies have been performed in the past for each of the 13 stream crossings evaluated. These studies provided contour information that CH2M HILL used to determine the character of any slopes located at or near each crossing. As a result, the scoring system for slope steepness presented in Table 3 was developed based on the general characteristics of the slopes at each crossing and previous experience regarding the stability of various slopes comprising materials native to the region. A score of 0 represents the lowest relative hazard regarding slope steepness and a score of 6 represents the highest relative hazard. TABLE 3 Slope Steepness Scoring System Slope Steepness (Percent) Score Less than 10 0 10 to 20 2 20 to 30 3 30 to 40 4 40 to 50 5 Greater than 50 6 Landform The shape of slopes, referred to as landform, has an impact on the potential for landslides and debris flows. Sharply convergent (concave) slopes tend to develop thicker soil deposits and are locations where drainage is concentrated (Dietrich and Dunne, 1978). Many studies report that convergent slope locations have higher landslide hazard than straight (planar) and divergent (convex) landforms (Tsukamoto et al., 1982; Reneau and Dietrich, 1987; Benda and Cundy, 1990; May, 1998; Millard, 1999). While landslides and debris flows do occur on slopes with no apparent distinctive landform, convergent landforms tend to have a higher landslide occurrence in western North America (Hofmeister, 2002). Table 4 presents the scoring system used for landform. The system was developed based on the general shape of slopes at the location of each stream crossing. A score of 1 represents the lowest relative hazard regarding geology and a score of 5 represents the highest relative hazard. TABLE 4 Landform Scoring System Landform Score* Divergent (convex) shape of slopes at stream crossing 1 Straight (planar) shape of slopes at stream crossing 3 Convergent (concave) shape of slopes at stream crossing 5 *A score of zero will be applied when there are no slopes or slopes of less than 10 percent steepness in the vicinity of the steam crossing. Geology The geology of Oregon is complex and varies widely across the state. Much of this variation can be attributed to the offshore Cascadia Subduction Zone, which is where the Juan de Fuca Plate is being actively subducted beneath the western margin of the North American Plate. The ongoing subduction has created accretionary wedges, fore‐arc sediment basins, uplift of the Oregon Coast Range, and a seismically active ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 7 area with numerous faults, volcanoes, mountains, and valleys (Orr et al., 1992). The geology exclusive to each stream crossing site can have a large impact on the landslide and debris flow hazard. The following sources were used to identify the mapped geology for each of the 13 stream crossings evaluated:  Oil and Gas Investigation of the Astoria Basin, Clatsop and Northwest Tillamook Counties, Northwest Oregon (Niem and Niem, 1985)  Oregon Geologic Data Compilation (OGDC) Release 5. OGDC‐5. (DOGAMI, 2009). Table 5 presents the scoring system used for geology. The system was developed based on the established characteristics of geologic formations mapped at each stream crossing. A score of 1 represents the lowest relative hazard regarding geology and a score of 5 represents the highest relative hazard. TABLE 5 Geology Scoring System Geology Score Geology mapped at stream crossing known to not be susceptible to landsliding hazard intact rock) 1 Geology mapped at stream crossing unknown or inconclusive regarding susceptibility to landsliding hazard 3 Geology mapped at stream crossing known to be susceptible to landsliding hazard 5 Land Use Impacts from human activity can have an adverse effect on the stability of slopes. For this landslide risk assessment, the primary land use activity that could potentially affect the stability of slopes at the 13 stream crossing evaluated is logging and the removal of vegetation at or near each location. Most evidence suggests that the more vegetation present at a site, the lower its susceptibility to landslides. Both vegetative type and cover can significantly impact the potential for landslides (Hofmeister, 2002). Therefore, aerial photographs were studied in order to identify the stream crossings that are located in areas in proximity to timber harvesting and clearcutting activities. Table 6 presents the scoring system used for land use. A score of 1 represents the lowest relative hazard regarding land use and a score of 3 represents the highest relative hazard. TABLE 6 Land Use Scoring Assessment Land Use Score No evidence of timber harvesting or clearcutting activities in vicinity of the stream crossing 1 Evidence of timber harvesting or clearcutting activities in vicinity of the stream crossing 3 Scour Potential Separate analyses were performed to evaluate the potential for scour at the 13 stream crossings. These analyses used characteristics such as stream segment slope, channel confinement, and entrenchment. Stream slope (gradient) at proposed Pipeline crossings were determined from field reconnaissance surveys. Where field reconnaissance surveys were not conducted, channel gradient was determined from 1:24,000 U.S. Geological Survey (USGS) topographic maps by measuring the distance between two contour lines encompassing the Pipeline crossing or by using Oregon 10‐meter Digital Elevation Model elevations. Channel confinement was determined by measuring the valley width or floodplain (distance between contour lines on either side of the channel based on 1:24,000 USGS topographic map) and comparing it to the channel width (bankfull width). ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 8 After determining channel gradient, channel confinement, and valley width at the Pipeline crossing, streams were grouped into categories based on their similarities and channel characteristics. Streams with specific similarities are expected to have similar responses to disturbance or are predisposed to specific conditions. These responses or conditions are based in part on the Washington Department of Natural Resources (WDNR) Watershed Assessment Methodology (1994) Channel Response Matrix. In addition, the Rosgen channel type (Rosgen, 1996) collected during field reconnaissance surveys was used to verify and support WDNR Channel Response Matrix characteristics. Table 7 presents a summary of the categories the stream crossings were grouped into and the associated scoring system used for scour potential. A score of 1 represents the lowest relative hazard regarding scour potential and a score of 5 represents the highest relative hazard. TABLE 7 Scour Potential Scoring System Scour Potential Score None or Slight 1 Moderate 2 Moderate/Severe 3 Severe 4 Severe (Mass‐Wasting Dominated) 5 Channel Migration Channel migration can have an adverse effect on stability of slopes if the stream channel erodes into the toe or base of a slope. As with scour potential, separate analyses were performed to determine the potential for channel migration at the proposed stream crossings. The analyses considered the valley width, channel width, and the gradient of each stream in order to determine the potential for channel migration. Table 8 presents a summary of the scoring system used for channel migration as it relates to landslide hazard. A score of 0 represents the lowest relative hazard regarding channel migration and a score of 3 represents the highest relative hazard. TABLE 8 Channel Migration Scoring Assessment Channel Migration Score Minimal bank erosion or channel migration potential 0 Bank erosion and channel migration 3 Summary A total of seven risk factors that have varying levels of influence on landslide hazard were evaluated for each stream crossing. As shown by the scoring systems presented in Tables 2 through 8, mapped landslide hazard has been determined to be the most critical of the seven risk factors. However, each risk factor does impact the landslide hazard at each of the 13 stream crossings. Landslides often have several causes, some of which are listed above, but only one trigger (Varnes, 1978). A trigger is an external stimulus such as intense rainfall or a seismic event, and the hazard associated with these triggers is considered to be relatively equal across all of the proposed stream crossings. Stream Crossings This section summarizes the evaluation of the landslide hazard at each of the 13 stream crossings. A score for each landslide hazard risk factor is presented with a justification for that score. A sum of each risk factor ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 9 score for a stream crossing is presented as the total score in order to quantify the relative landslide hazard at that specific stream crossing. Barrett Slough (S5BCL064) The Barrett Slough (stream ID S5BCL064) crossing is located at MP 4.4 along the Pipeline alignment in an alluvial valley created by the Lewis and Clark River approximately 2 miles south of the confluence of the Lewis and Clark River and Youngs Bay. The width and depth of the slough channel at the crossing are approximately 12 and less than 3 feet, respectively. Table 9 presents a score value and justification for each risk factor evaluated for this crossing. Stream crossing Figure 6A‐5 presents an aerial view and cross‐section of the crossing. TABLE 9 Scoring Assessment—Barrett Slough (S5BCL064) Risk Factor Score Justification Mapped Landslide Hazard 0 No documented or mapped landslide hazard in vicinity of crossing. Slope Steepness 0 Stream located in alluvial valley where topography is primarily flat. Slope geometry approximately equal to 0. Landform 0 No slopes adjacent to stream crossing. Geology 3 Geology at crossing mapped to be quaternary alluvium (Qal) consisting of unconsolidated flood plain deposits of clay, silt, sand, and basalt gravel (Niem and Niem, 1985). Land Use 1 Land use primarily consists of agriculture. Stream setting is an alluvial valley with sporadic trees. No timber harvesting in general vicinity due to stream location. Scour Potential 1 Analysis results show none or slight scour potential. Channel Migration 3 Analysis results show bank erosion and channel migration potential. Total Score 8 Heckard Creek (S1BCL001) The Heckard Creek (stream ID S1BCL001) crossing is located at MP 7.9 for the main Pipeline alignment in the foothills along the western flank of the Oregon Coast Range in a forested setting. The width and depth of the creek channel at the crossing are approximately 10 and 3 feet, respectively. Table 10 presents a score value and justification for each risk factor evaluated for this crossing. Figure 6A‐8 presents an aerial view and cross‐section of the stream crossing. TABLE 10 Scoring Assessment—Tributary of Heckard Creek (S1BCL001) Risk Factor Score Justification Mapped Landslide Hazard 5 Landslide topography mapped at crossing location (SLIDO‐2). Slope Steepness 2 Stream crossing located in foothills along western flank of Coast Range. Average slope geometry of slope located south of crossing approximately equal to 15 to 20 percent. Landform 3 General shape of slopes located at crossing is planar. Geology 1 Geology at crossing mapped to be Smuggler Cove Formation (Tsc2), which consists primarily of thick‐bedded bioturbated tuffaceous claystone and siltstone (Niem and Niem, 1985). Land Use 3 Evident that predominant land use activity in the general vicinity of the crossing is timber harvesting. Scour Potential 1 Analysis results show a slight potential for scour. Channel Migration 3 Analysis results show bank erosion and channel migration potential. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 10 TABLE 10 Scoring Assessment—Tributary of Heckard Creek (S1BCL001) Risk Factor Score Justification Total Score 18 Alder Creek (S2BCL008B) The Alder Creek (stream ID S2BCL008B) crossing is located at MP 31.4 of the Pipeline alignment in the Oregon Coast Range in a forested setting approximate 1 mile east‐northeast from Camp 18 and US Highway 26. The width and depth of the creek channel at the crossing are approximately 13 and 4 feet, respectively. Table 11 presents a score value and justification for each risk factor evaluated for this crossing. Figure 6A‐10 presents an aerial view and cross‐section of the stream crossing. TABLE 11 Scoring Assessment—Alder Creek (S2BCL008B) Risk Factor Score Justification Mapped Landslide Hazard 8 Stream is near potential gullying/rapid erosion location. Crossing location is also in area mapped to have mass movement topography (Beaulieu, 1972b). Slope Steepness 4 Stream crossing located in Oregon Coast Range. Average slope geometry of slope located south of crossing approximately equal to 30 to 40 percent. Landform 1 General shape of steeper slopes at stream crossing is divergent. Geology 1 Geology at crossing mapped to be either Sager Creek Formation (Tg) or Keasey Formation (Tkj). Sager Creek Formation primarily consists of well‐laminated micaceous and carbonaceous mudstone. Keasey Formation primarily consists of thin‐bedded to laminated tuffaceous to glauconitic mudstone (Niem and Niem, 1985). Land Use 3 Evident that predominant land use activity in the general vicinity of the crossing is timber harvesting. Clearcut located adjacent to stream crossing. Scour Potential 3 Analysis results show a moderately severe potential for scour. Channel Migration 0 Analysis results show no or minimal potential for bank erosion or channel migration. Total Score 20 North Fork Wolf Creek (S6BCO002) The North Fork Wolf Creek (stream ID S6BCO002) crossing is located at MP 47.6 along the Pipeline in the Oregon Coast Range in a forested setting approximately 1,200 feet north of US Highway 26 about three‐ quarters of a mile west of the intersection with North Fork Wolf Creek Road. The width and depth of the creek channel at the crossing are approximately 35 and 5 feet, respectively. Table 12 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐14 presents an aerial view and cross‐section of the stream crossing. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 11 TABLE 12 Scoring Assessment—North Fork Wolf Creek (S6BCO002) Risk Factor Score Justification Mapped Landslide Hazard 8 Stream is near potential gullying/rapid erosion location. Crossing location is also adjacent to area mapped as landslide topography (CH2M HILL, 2013), potential rapidly moving landslide (Hofmeister, 2002). Slope Steepness 5 Stream crossing located in Oregon Coast Range. Geometry of slopes adjacent to crossing ranges from 40 to 50 percent on south side of creek and between 20 and 30 percent on north side of creek. Landform 3 General shape of slopes located at crossing is planar. Geology 5 Geology consists of marine sedimentary rock. Deep landslides are uncommon in this geology, but shallow landslides are known to occur. Land Use 3 Evidence of clearcutting activities northeast of the stream crossing. Scour Potential 2 Analysis results show a slight to moderate potential for scour at the stream crossing. Channel Migration 0 Minimal bank erosion or channel migration potential. Total Score 26 Clear Creek (S3BCO012) The Clear Creek (stream ID S3BCO012) crossing is located at MP 50.5 along the Pipeline alignment in the Oregon Coast Range in a forested setting approximately 2 miles north of US Highway 26 about 2 miles west of Timber Road. The width of the creek channel at the crossing is approximately 30 feet and the depth of the creek is unknown. Table 13 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐15 presents an aerial view and cross‐section of the stream crossing. TABLE 13 Scoring Assessment—Clear Creek (S3BCO012) Risk Factor Score Justification Mapped Landslide Hazard 2 No documented or mapped landslide hazard at crossing, but Potential Rapidly Moving Landslide located northeast of crossing locations (Hofmeister, 2002). Slope Steepness 3 Slope ranges between 20 and 30 percent with steeper slopes located northeast of stream crossing. Landform 1 Slopes on either side of stream crossing are divergent. Geology 3 Geology at crossing mapped to Marine Sedimentary Rock consisting of sandstone – specifically Cowlitz Formation, Clark and Wilson Sandstone Member (Tccw) (DOGAMI, 2009). Land Use 3 Evidence of clearcutting activities east of the stream crossing. Scour Potential 3 Analysis results show a moderate to severe potential for scour. Channel Migration 0 Analysis results show minimal potential for bank erosion and channel migration. Total Score 15 Cedar Creek (S3BCO107) The Cedar Creek (stream ID S3BCO107) crossing is located at MP 55.7 of the Pipeline alignment in the Oregon Coast Range in a forested setting approximately 1 mile west of the Vernonia Airfield and approximately 0.15 mile southwest of Koster Road. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 12 The width and depth of the creek channel at the crossing are approximately 20 and 5 feet, respectively. Table 14 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐16 presents an aerial view and cross‐section of the stream crossing. TABLE 14 Scoring Assessment—Cedar Creek (S3BCO107) Risk Factor Score Justification Mapped Landslide Hazard 8 Mapped landslide located south of stream crossing with small areas of rapid erosion and gullying potential (CH2M HILL, 2013). Slope Steepness 4 Creek is deeply incised with slopes immediately adjacent to the creek crossing ranging in steepness between 30 and 40percent. Slopes further from incised creek are flatter with typical slopes less than 10 percent. Landform 3 General shape of slopes located at crossing is planar. Geology 3 Geology at crossing mapped to be Keasey Formation (Tk), which primarily consists of tuffaceous sedimentary rocks (DOGAMI, 2009). Land Use 3 Evidence of clearcutting activities north of the stream crossing. Scour Potential 2 Analysis results show slight to moderate scour potential. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 23 Clatskanie River (S99CO020) The Clatskanie River (stream ID S99CO020) crossing is located at MP 70.7 of the main Pipeline alignment on the east side of the Oregon Coast Range. The crossing is in a forested area approximate 0.1 mile west of Schaffer Road, 2 miles north of its intersection with Pittsburg Road, and about 10 miles west of the Columbia River. The width of the creek channel is estimated to be approximately 20 and the depth of the creek is expected to range between 2 feet and 7 feet for the majority of the year. Table 15 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐19 presents an aerial view and cross‐ section of the stream crossing. TABLE 15 Scoring Assessment—Clatskanie River (S39CLI001) Risk Factor Score Justification Mapped Landslide Hazard 8 Mapped landslide located immediately west of stream crossing with small areas of rapid erosion and gullying potential (CH2M HILL, 2013). Slope Steepness 4 Geometry of slopes adjacent to crossing generally range from 25 to 35 percent. Landform 3 General shape of slopes located at crossing is planar. Geology 5 Geology at crossing mapped Scappoose Formation (Ts) consisting of sandstone (DOGAMI, 2009). However, it is believe that shallow deposits of recent quaternary alluvium (Qal) overly the sandstone at this crossing location (CH2M HILL, 2013). Land Use 3 The stream crossing is immediately east of a clearcut. Scour Potential 1 Analysis results show none to slight scour potential. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 24 ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 13 Little Clatskanie River (S5BCO001) The Little Clatskanie River (stream ID S5BCO001) crossing is located at MP 71.8 of the Pipeline alignment in the Oregon Coast Range, approximately 0.2 miles east of Janshaw Road. The width and depth of the creek channel at the time of a site visit were less than 10 and less than 2 feet, respectively. Table 16 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐20 presents an aerial view and cross‐section of the stream crossing. TABLE 16 Scoring Assessment—Little Clatskanie River (S5BCO001) Risk Factor Score Justification Mapped Landslide Hazard 8 Mapped landslide located west of stream crossing with potential for rapid erosion and/or gullying at stream crossing (CH2M HILL, 2013). Slope Steepness 2 Geometry of slopes adjacent to crossing ranges from 10 to 20 percent. Landform 3 General shape of slopes located at crossing is planar. Geology 1 Geology at crossing mapped Columbia River Basalt Group (Tcr) consisting of basalt rock (DOGAMI, 2009). However, it is believe that shallow deposits of recent quaternary alluvium (Qal) overly the basalt at this crossing location (CH2M HILL, 2013). Land Use 3 The stream crossing is immediately west of a clearcut. Scour Potential 3 Analysis results show moderate to severe scour potential. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 20 Milton Creek (S3BCO010) The Milton Creek (stream ID S3BCO010) crossing is located at MP 73.0 of the Pipeline alignment in the Oregon Coast Range approximately 0.1 mile east of S Canaan Road. At the time of the field visit to evaluate the stream characteristics, the width and depth of the creek channel at the crossing were approximately 10 and less than 2 feet, respectively. Table 17 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐21 presents an aerial view and cross‐ section of the stream crossing. TABLE 17 Scoring Assessment—Milton Creek (S3BCO010) Risk Factor Score Justification Mapped Landslide Hazard 8 Mapped potential for rapid erosion and/or gullying at stream crossing (CH2M HILL, 2013). Slope Steepness 4 Geometry of slopes adjacent to crossing generally range from 25 to 35 percent. Landform 1 Slopes on either side of stream crossing are divergent. Geology 1 Geology at crossing mapped Columbia River Basalt Group (Tcr) consisting of basalt rock (DOGAMI, 2009). However, it is believe that shallow deposits of recent quaternary alluvium (Qal) overly the basalt at this crossing location (CH2M HILL, 2013). Land Use 1 No evidence of timber harvesting or clearcutting activities in vicinity of the stream crossing. Scour Potential 3 Analysis results show moderate to severe scour potential. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 18 ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 14 Milton Creek (S6BCO001) The Milton Creek (stream ID S6BCO001) crossing is located at MP 74.9 of the Pipeline alignment in the Oregon Coast Range. The crossing is approximately 0.2 mile south of Pinkney Road. At the time of the field visit to evaluate the stream characteristics, the width of the creek channel at the crossing was approximately 20 feet. No information was obtained relative to the depth of the creek channel. Table 18 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐22 presents an aerial view and cross‐section of the stream crossing. TABLE 18 Scoring Assessment—Milton Creek (S6BCO001) Risk Factor Score Justification Mapped Landslide Hazard 5 Mapped landslide hazards both north and south of crossing location with potential for gullying and/or rapid erosion upstream and of crossing, but not directly at crossing location. Slope Steepness 5 Geometry of slopes adjacent to crossing generally range from 40 to 50 percent east of the stream crossing and less than 20 percent west of the stream crossing. Landform 1 Slopes on either side of stream crossing are divergent. Geology 5 Geology at crossing mapped to be Scappoose Formation, Oligocene Sediment (Tos) which primarily consists of sandstone (DOGAMI, 2009). However, it is believe that shallow deposits of recent quaternary alluvium (Qal) overly the sandstone at this crossing location (CH2M HILL, 2013). Land Use 3 The stream crossing is west of a clearcut area. Scour Potential 3 No data are available for the relative scour potential at the crossing. Therefore, a medium score of 3 is used. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 22 Merrill Creek (S3BCO017) The Merrill Creek (stream ID S3BCO017) crossing is located at MP 76.4 of the Pipeline alignment in the foothills of the Oregon Coast Range, approximately 1.1 miles due south of the intersection of Hawks Run Lane and Canaan Road. At the time of the field visit to evaluate the stream characteristics, the full width of the stream channel was noted at 35 feet but no information was recorded on the width or depth of the stream. Table 19 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐23 presents an aerial view and cross‐section of the stream crossing. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 15 TABLE 19 Scoring Assessment—Merrill Creek (S3BCO017) Risk Factor Score Justification Mapped Landslide Hazard 8 Mapped landslide hazards in the vicinity, but not directly at the crossing location. Potential for gullying and/or rapid erosion in the vicinity of the crossing location. Slope Steepness 3 Geometry of slopes adjacent to crossing generally range from 20 to 30 percent east of the stream crossing and less than 20 percent west of the stream crossing. Landform 5 Slope to the east of the crossing is divergent and the slope to the west of the crossing is convergent. Geology 1 Geology at crossing mapped Columbia River Basalt Group (Tcr) consisting of basalt rock (DOGAMI, 2009). Land Use 1 No evidence of recent timber harvesting or clearcutting in the vicinity of the stream crossing. Scour Potential 2 Analysis results show slight to moderate scour potential. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 20 Tributary of Merrill Creek (S3BCO122) The Tributary of Merrill Creek (stream ID S3BCO122) crossing is located at MP 78.4 of the Pipeline alignment in the foothills of the Oregon Coast Range, approximately 0.8 mile south of the terminus of Hills Haven Avenue. At the time of the field visit to evaluate the stream characteristics, the width of the creek channel at the crossing was approximately 10 feet. No information was obtained relative to the depth of the stream. Table 20 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐24 presents an aerial view and cross‐section of the stream crossing. TABLE 20 Scoring Assessment—Tributary of Merrill Creek (S3BCO122) Risk Factor Score Justification Mapped Landslide Hazard 8 Both sides of stream crossing are shows as landslide topography. Multiple small areas where there is a potential for gullying and/or rapid erosion are located in the vicinity of the crossing location. Slope Steepness 4 Geometry of slopes adjacent to crossing ranges from 30 to 40 percent. Landform 3 Slope to the east of the crossing is divergent and the slope to the west of the crossing is planar. Geology 5 Geology at crossing mapped Scappoose Formation (Ts) consisting of sandstone (DOGAMI, 2009). However, it is believe that shallow deposits of recent quaternary alluvium (Qal) overly the sandstone at this crossing location (CH2M HILL, 2013). Land Use 1 No evidence of recent timber harvesting or clearcutting in the vicinity of the stream crossing. Scour Potential 2 Analysis results show slight to moderate scour potential. Channel Migration 0 Minimal potential for bank erosion and channel migration potential. Total Score 23 Deer Island Slough (S99CO011) The Deer Island Slough (stream ID S99CO011) crossing is located at MP 81.6 of the Pipeline alignment at the edge of the Coast Range in the Willamette Valley ecoregion. The crossing is immediately adjacent to the Columbia River and is bordered on both sides by open areas. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 16 The proposed Pipeline alignment is along a flood control levee that also serves as an access road, called Dike Road, to Deer Island. The slough flows under Dike Road via culverts. The planned location for the Pipeline would be along the toe of the existing levee, above the culverts that carry water of the Deer Island Slough. Therefore, the proposed location of the Pipeline would not have any impacts to the landslide potential at this crossing. However, an assessment of the potential hazard is included to evaluate the potential hazard at the crossing in the unlikely event that the location of the Pipeline is modified. At the time of the field visit to evaluate the stream characteristics, the width of the creek channel at the crossing was approximately 38 feet. No information was obtained relative to the depth of the stream. Table 21 presents a score value and justification for each risk factor evaluated for the crossing. Figure 6A‐25 presents an aerial view and cross‐section of the stream crossing. TABLE 21 Scoring Assessment—Deer Island Slough (S99CO011) Risk Factor Score Justification Mapped Landslide Hazard 0 No documented or mapped landslide hazard in vicinity of crossing. Slope Steepness 0 Stream located in alluvial valley where topography is primarily flat. Slope geometry approximately equal to 0. Landform 0 Slopes adjacent to stream crossing are less than 10 percent. Geology 5 Geology at crossing mapped to be artificial fill (af), which makes up the Dike Road. The material around the dike road is mapped as Alluvium (Qa) (DOGAMI, 2009). Land Use 1 No timber harvesting in general vicinity because of stream location. Scour Potential 3 Analysis results show moderate to severe scour potential. Channel Migration 3 Analysis results show bank erosion and channel migration potential. Total Score 12 Summary of Landslide Risk Assessment The systematic assessment methodology described in this technical memorandum resulted in the quantification of relative landslide hazard at each of the 13 selected Pipeline stream crossings. Table 22 presents the range of total score values relative to the landslide hazard. TABLE 22 Relative Landslide Hazard Total Score Relative Landslide Hazard 10 or less Very Low 11 to 15 Low 16 to 20 Moderate 21 to 25 High 25 and greater Very High Table 23 presents a summary of the scores for each risk factor applied to each of the 13 selected stream crossings, as well as the total score and corresponding relative landslide hazard. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 17 TABLE 23 Landslide Risk Assessment Summary Waterbody Stream ID Mapped Landslide Hazard Slope Steepness Landform Geology Land Use Scour Potential Channel Migration Total Score Relative Landslide Hazard Barrett Slough S5BCL064 0 0 3 0 1 1 3 8 Very Low Heckard Creek S1BCL001 5 2 3 1 3 1 3 18 Moderate Alder Creek S2BCL008B 8 4 1 1 3 3 0 20 Moderate North Fork Wolf Creek S6BCO002 8 5 3 5 3 2 0 26 Very High Clear Creek S3BCO012 2 3 1 3 3 3 0 15 Low Cedar Creek S3BCO107 8 4 3 3 3 2 0 23 High Clatskanie River S99CO020 8 4 3 5 3 1 0 24 High Little Clatskanie River S5BCO001 8 2 3 1 3 3 0 20 Moderate Milton Creek S3BCO010 8 4 1 1 1 3 0 18 Moderate Milton Creek S3BCO001 5 5 1 5 3 3 0 22 High Merrill Creek S3BCO017 8 3 5 1 1 2 0 20 Moderate Tributary of Merrill Creek S3BCO122 8 4 3 5 1 2 0 23 High Deer Island Slough S99CO011 0 0 0 5 1 3 3 12 Low ID = identification. Limitations This memorandum has been prepared for the exclusive use of LNG Development Company, LLC, and the Oregon Pipeline Company, LLC, and CH2M HILL, for application to the specific stream crossings described along the Oregon Pipeline Project in Clatsop and Columbia counties, Oregon. It has been prepared in accordance with generally accepted geotechnical engineering practice. No other warranty, express or implied, is made. The geologic information contained in this memorandum is from published geology and geologic hazard maps. Data related to ground surface topography are from various sources that include in order of decreasing accuracy and detail, field surveys, aerial photography, and 1:24,000 USGS topographic maps. Information on land use is based on aerial photographs available at the time of this assessment and observations made during field reconnaissance of sites where access to stream crossings could be obtained. The interpretations and recommendations contained in this memorandum are based on limited data and should be considered preliminary. Site‐specific information for each Pipeline stream crossing should be collected. CH2M HILL is not responsible for any claims, damages, or liability associated with interpretation of subsurface data or for reuse of subsurface data, without CH2M HILL’s express written authorization. References Beaulieu, John D. 1972a. Hazard Map of the Birkenfeld Quadrangle, Oregon. Oregon Department of Geology and Mineral Industries. Bulletin 79. Map Scale 1:62,500. Beaulieu, John D. 1972b. Hazard Map of the Saddle Mountain Quadrangle, Oregon. Oregon Department of Geology and Mineral Industries. Bulletin 79. Map Scale 1:62,500. Beaulieu, John D. 1973. “Environmental Geology of Inland Tillamook and Clatsop Counties.” Oregon Department of Geology and Mineral Industries. Bulletin 79. ---PAGE BREAK--- LANDSLIDE AND DEBRIS FLOW: RELATIVE RISK ASSESSMENT FOR THE BIDIRECTIONAL PROJECT PIPELINE 18 Benda, L.E. and T.W. Cundy. 1990. “Predicting Deposition of Debris Flows in Mountain Channels.” Canadian Geotechnical Journal. Vol. 27, No. 4, pp. 409‐417. Burns, W. and Madin, I. P. 2009. Protocol for Inventory Mapping of Landslide Deposits from Light Detection and Ranging (LIDAR) Imagery. Oregon Department of Geology and Mineral Industries. Special Paper 42. CH2M HILL. 2009. Geologic Hazard: Slope Instability/Landslide Inventory Map. Prepared for Resource Report 6. Prepared for Oregon LNG. CH2M HILL. 2013. Geologic Hazard: Slope Instability/Landslide Inventory Map. Prepared for Resource Report 6. Prepared for Oregon LNG. November. Dietrich, W.E. and T. Dunne. 1978. “Sediment budget for a small catchment in mountainous terrain.” fur Geomorphologie. Bd. 29, pp. 191‐206. Oregon Department of Geology and Mineral Industries (DOGAMI). 2009. Oregon Geologic Data Compilation (OGDC) Release 5. OGDC‐5. Compiled by Lina Ma, Ian P. Madin, Keith V. Olson, and Rudie J. Watzig. Hofmeister, R. Jon. 2000. Slope Failures in Oregon: GIS Inventory for Three 1996/97 Storm Events. Oregon Department of Geology and Mineral Industries. Special Paper 34. Hofmeister, R. Jon. 2002. Hazard Map of Potential Rapidly Moving Landslides in Western Oregon. Oregon Department of Geology and Mineral Industries. Interpretive Map Series IMS‐22. May, C.L. 1990. Debris Flow Characteristics Associated with Forest Practices in the Central Oregon Coast Range. Oregon State University. Corvallis, Oregon. Master’s Thesis. Millard, T. 1999. Debris Flow Initiation in Coastal British Columbia Gullies. British Columbia Forest Service. Forest Research Technical Report TR‐002. Niem, Alan R. and Wendy A. Niem. 1985. Oil and Gas Investigation of the Astoria Basin, Clatsop and Northernmost Tillamook Counties, Northwest Oregon. Oregon Department of Geology and Mineral Industries, Oil and Gas Investigations 14. Map Scale 1:100,000. Orr, Elizabeth William N. Orr, and Ewart Baldwin. 1992. Geology of Oregon. Kendall/Hunt Publishing Company. Dubuque, Iowa. Reneau, S.L. and W.E. Dietrich. 1987. The Importance of Hollows in Debris Flow Studies. Examples from Marin County, California, in Costa, J.E., and Wieczorek, G.F., eds., Debris Flows/Avalanches. Process, Recognition, and Mitigation. Geological Society of America Reviews in Engineering Geology VII. Robison, E.G., K. Mills, J. Paul, L. Dent, and A. Skaugset. 1999. Storm Impacts and Landslides of 1996. Final Report. Oregon Department of Forestry Forest Practices Technical Report 4. Rosgen, Dave. 1996. Applied River Morphology. Copyright 1996 by Wildland Hydrology, Pagosa Springs, Colorado. Tsukamoto, T. Ohta, and H. Noguchi. 1982. “Hydrological and geomorphological studies of debris slides on forested hillslopes in Japan, in recent developments in the explanation of prediction of erosion and sediment yield.” Proceedings of the Exeter Symposium. July 1982. pp. 89‐98. Varnes, D.J. 1978. Slope‐Movement Types and Processes. Special Report 176: “Landslides: Analysis and Control” (R.L. Schuster and R.J. Krizek, eds.). Transportation Research Board, National Research Council, Washington D.C., pp. 11‐33. Washington Department of Natural Resources (WDNR). 1994. Board Manual: Standard Methodology for Conducting Watershed Analysis Under Chapter 222‐22 WAC. Washington Department of Natural Resources, Olympia, Washington. ---PAGE BREAK--- Attachment Landslide Inventory and Geologic Hazard Maps This attachment has been removed. The full memo containing the maps was filed as appendix 6B to the Oregon LNG Applicant-Prepared Draft Biological Assessment and is available on FERC's eLibrary at http://www.ferc.gov/docs-filing/elibrary.asp under Docket No. CP09-6-001, Accession No. 20131230-5208. ---PAGE BREAK---