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Borehole Log February 06 - 13, 1996
110:- BOREHOLE LOG Project: 1996 PORTUGUESE BEND LANDSLIDE STUDY Boring No.: PBS-1 Sheet 1 of 3. GPS boring location: m4,01-8,018 E4 178 700 GPS boring el-FT-Mon: 179.6' Drillers: A. Parra to 173 fet w feet air rig; E. Sanduval to 277 t with CME 95 core rig Drilling company: Layne Environmental Services Drilled on: 2/6 to 13/96 Geology logged by: R. Crook; Dana Cole; P. Ehlig Depth Lithic Description (feet) log 0- Landslide debris (0 to 175.4') 0 to 42' breccia; rock fragments in soft yellow brown (10YR5/4) matrix composed of fine a.� sand, silt and clay; soft. 10- as .• Q 20- ~ • • ;fie► ._.. 30- .0 40- .-G, --:; 42 to 115' clay; silty, sandy and gravelly; dense; dark yellow brown (10YR4/6) to very dark gray Brown (10YR3/2); some charcoal fragments at 58'; moist; appear to be lake beds. • 50- v: 7-i -a.. • 60- — '7s 70- cam, • G 80- - G O_ 90- th 100- =� I10- • 115 to 175' variable amounts of poorly sorted clay, silt, sand and gravel; gravel includes angular to subangular clasts of dolostone, chert and basalt; various shades of yellow to orange brown (10YR5/4, 10YR5/6, 10YR6/6; moist; appears to be of bedded 120- = alluvial origin. Note: Log approximately the same sane from 120 feet to base of slide at 175 feet; therefore not shown. CORE LOG PBS-1, Sheet 2 4111 Date Core Run Recovery Depth Graphic Dip Descriptive log and box in feet, in log of times S & base feet bedding 3.4/3.4 Sheared bentonitic clay; (5Y7/6) above slide base. 2/8/96 1005 m.= yellow 1 1 175- S.B.�yy 11 175.4' slide base; lineation plunges 10 degrees. C -. Altamira 5nafe 3eneath slide base; alternating light to 13:20 107.0 r : :%,' ar greens gray (N7 to 5Y4/1) beds 1 to 10 cm thick; 177.75' fine-grained sandstone bed; 3 cm thick; medium - . dark gray (N4). 5.0/5.0 180- y 8: 13 1005 - Beds offset about 3 cm along steeply inclined shear from 14:25 1 2 182.0 - 178.0 to 183.0'. 5.0/5.0 185- 1001 - 14:50 2 3 187,0 - 187.8' Bentonitic bed 5 mm thick. _ 8: 9 2 4 5.0/5:0 190- �� 100% - 15:25 192.0 - ....:.-• B: 10 - -7 Core fractured during drilling. 3 5 4.0/5.0 195- --' 16:15 197. 0 - • 8: 17 - - C'-{ 8: 23 - i- Core fractured during drilling. 3 & 4 6 4.4/5.0 200- is 88S - 16:57 202 - .:•_..i..:4 B: 11 Mostly siltstone and fine-grained sandstone with a few 2/9/96thin bentonitic beds. 1.3/5.0 205- . 27% - 10:00 4 7 207.0 - !s - 209 to 270.8 Portuguese Tuff 4.4/5.0 210- ��s Bentonite; very fine grained; bedding- difficult to make 881 - r_,_ out; light to medium dark gray (N7 to N5); develops 12:20 4 8 212.0 - I;_= closely spaced curved cracks as it dries. 83% 149149.0 '�J -_ .0 215_ [ 8: 20 215 to 227' core severely broken during drilling. 100% 13:20 4 8 5 9 217 - f = 144 5.0/5.0 - 1001 220- 15:15 5 10 221.0 ii 2/12/96 16:01 5 11 0.6/1.0 222 - Start 10:00 - =a 5 12 4.0/5.0 225- 801.5 - 1.:..-1 Bentonite becomes coarser grained; includes sandy beds. 12:57 227.0 / 6 13 2.6/2.6 - if- '. 13:30 229.6 - I."! 100% 230- i7 14:00 6 14 232 - 'Evi 231 to 232' swirled structure caused by soft sediment 2.5/2.5 - � 8: 12 deformation. 100% • - J� 14:40 6 15 234.5 2.5/2.5 235- 235.6 to 235.9' cross bedding in coarse sandy bebs. 1002 15:04 7 16 237.0 -III i-i Core broken during drilling. - i 7 240- �/ CORE LOG PBS-1, Sheet 3 of 3. 11" Date Core Run Recovery Depth Graphic Dip Descriptive log and box in feet, in log of times Z & base feet bedding 7 17 5.0/5.0 240- . . • Portuguese Tuff continued. 1001 - JC Light gray bentonitic tuff (N7 to N6); sandy. 16:25 242.0 - - 2/13/96 7 18 1.0/2.5; 401 - .. -- Start - Start 7:00 244.5 - 7 8 19 2.1/2.5 245- )` 8: 7 84% . 08:10 247.0 - 8 20 0.5/2.5; 201 - :k1 08: 249.5 8 21 2.5/2.5 250- ;4 B: 17 1001 - ::1 09:30 252.0 - -ir.: 8/9 22 2.5/2.5; 100% - ')L". B: 15 10:00 254.5 - 9 23 2.0/2.5 255- y• 8: 16 80%. - 10:25 . 257.0 . - '..',A.'..',A. • 9 24 2.3/2.5; 92% - ..e.-) Core broken during drilling. 10:45 259.5 - '::)' 9/10 25 2.5/2.5 260- 100% - 12- B: 15 11:12 262.0 Conglomeratic with mudstone rip-up clasts. 10 26 1.9/2.5; 76% 11:35 264.5 - ,f 10 27 2.5/2.5 265_ i�Ll 100% 11:55 267.0 - 10 28 2.5/2.5; 100% - 1::: 12:30 269.5 - 1111 10/11 29 0.9/2.5 270- 270.8' Base of Portuguese Tuff underlain by siliceous 36Z - ,:::-.7,i siltstone; light gray granule conglomerate on slightly 13:15 272.0 - ,, irregular surface above laminated to thin bedded (3 to 20 ;- ��, mm) medium gray to dark brownist gray siltstone Recovered chewed up fragments only. 11 30 2.5/5.0 275-- °-i1 50% - ij1 15:30 277 - ,--- Total depth 277 feet. Inserted 2 inch PYC to 180 feet for use to determine depth of active slide plane and use for ground water monitoring.