GM_05-18_Design_&_Construction_Recommendations.pdf

Western Federal Lands Highway Division 610 E. Fifth Street

Vancouver, WA 98661 Phone 360-619-7700

Fax 360-619-7846

DATE: February 17, 2018

TO: Betty Chon

Project Manager

FROM: Robert Kraig

Geotechnical Engineer

SUBJECT: Geotechnical Memo 05-18 Geotechnical Design & Construction Information

Mount Baker Emergency Repairs 2016

WA FS ERFO 2016(1)-20(1)

Mt. Baker-Snoqualmie National Forest, WA

INTRODUCTION

In September 2016, the Western Federal Lands Highway Division conducted site reconnaissance to investigate incurred damage to forest roads in the Mt. Baker-Snoqualmie National Forest, Washington. This memorandum contains geotechnical and construction recommendations for the damage sites located on Forest Development Roads (FDR):

• 3100 at milepost (MP) 6.7,

• 3140 at MP 0.5,

• 3900 at MP 2.27,

• 1130 at MP 0.1 and 1144 MP 4.1, and

• 1050 at MP 1.7

Note that the FDR 1144 MP 4.1 site defines the lower limit of the incurred damage beginning at a higher elevation along the FDR 1130 MP 0.1 site (the upper limit), thus they are treated as a single repair as discussed later in this memorandum.

PROJECT DESCRIPTION

The five sites addressed in this memorandum are part of a larger regional damage event that recently qualified for assistance under the Emergency Relief of Federally Owned Roads (ERFO) program due to damage likely sustained during the winter of 2015. Figure 1 shows the general location of the project sites relative to Bellingham, WA. The sites are in the Mt. Baker-Snoqualmie National Forest

(Forest) with all but the FDR 1050 MP 1.7 site located in Whatcom County. The FDR 1050 MP 1.7 site is in Skagit County. The sites range from about 40 to 70 miles driving distance from Bellingham, and are located along narrow forest road corridors. Site vicinities are shown in Figures 2a through 2c.

Figure 1: Project location

Figure 2a: Site vicinity of FDR 3100 MP 6.7 & FDR 3140 MP 0.5 relative to Glacier, WA

(Image captured from 8/2016 Google Earth imagery)

Project

Location

Figure 2b: Site vicinity of FDR 3900 MP 2.27 relative to Glacier, WA

(Image captured from 7/2017 Google Earth imagery)

Figure 2c: Site vicinity of FDR 1130 MP 0.1/1144 MP 4.1 and FDR 1050 MP 1.7 relative to

Hamilton, Concrete, Rockport and Marblemount, WA (Image captured from 12/2016 Google Earth imagery)

GEOLOGY

Geologic map excerpts described under this section were obtained from the Geologic Map of the Mount Baker 30- by 60-Minute Quadrangle, Washington by R.W. Tabor, R.A. Haugerud, Wes

Hildreth, and E.H. Brown, USGS, 2003. Discussions of the geologic map units follows.

FDR 3100 MP 6.7 and FDR 3140 MP 0.5

Figure 3a shows that FDR 3100 MP 6.7 and FDR 3140 MP 0.5 are located within a mapped unit of

Bell Pass mélange, undivided (Kjb) of the Cretaceous to Late Jurassic as follows:

Disrupted argillite, slate, phyllite sandstone, semischist, ribbon chert, and basalt of the Elbow Lake Formation of Brown and others (1987), with tectonic blocks of meta-igneous rocks, gneiss, schist, ultramafic rocks, and marble. Sandstone commonly lithic subquartzose, either volcanic rich and

(or) chert rich; argillite is mostly scaly, and grades into slate and phyllite. Greenstones are recrystallized basalt, mafic tuff, diabase, and gabbro and commonly make the most prominent outcrops. Metamorphic minerals in greenstones and metasedimentary rocks are chlorite, epidote, albite, pumpellyie, rare actinolite and (or) lawsonite.

Figure 3a: FDR 3100 MP 6.7 & FDR 3140 MP 0.5 shown within geologic map excerpt

A mapped unit of younger alluvium (Qyal) of the Holocene is shown directly east of the FDR 3100

MP 6.7 site. The Qyal mapped unit is described as:

Moderately sorted deposits of cobble gravel to pebbly sand along rivers and streams. Generally, unvegetated surfaces; gradational with both units Qf (alluvial fan deposits) and Qb (bog deposits).

Note that landslide deposits (Ql) are mapped nearby to the southwest of FDR 3100 MP 6.7.

bcs

Qya

FDR 3900 MP 2.27

Figure 3b shows that the FDR 3900 site is located within a mapped unit of thick bedded sandstone and argillite (KJnt) described as volcanic lithic sandstone with minor interbeds of argillite (early Cretaceous to middle Jurassic).

Figure 3b: FDR 3900 MP 2.27 shown within geologic map excerpt

FDR 1130 MP 4.1 & 1144 MP 0.1

Figure 3c shows this repair site to be located within a unit of volcanic rocks of Mount Herman (Pcmv) described as: Breccia, pillows, pillow breccia, and associated volcanic sandstone of basalt or basaltic andesite composition. Most volcanic rock are plagioclase-phyric, some are amygdaloidal. Unit weathers orange-brown; dark to light-green on fresh surfaces. (Permian)

An area of mapped alpine glacial deposits (Qag) is present to the east. These deposits are described as: ranging from boulder till in uplands and upvalley to gravel or sand outwash on broad valley floors.

On valley sides and uplands, includes areas veneered with drift but also includes subordinate areas of bedrock, alluvial fans, colluvium, or talus deposits. On valley floors also includes small fans, bogs, and modern stream alluvium. Areas of thin, sparse drift not distinguished from bedrock. (Holocene and Pleistocene)

Figure 3c: FDR 1130 MP 4.1 & FDR 1144 MP 0.1 shown within geologic map excerpt

FDR 1050 MP 1.7

Figure 3d shows this site to be located at the contact of Alluvial-fan deposits (Qf) and Napeequa

Schist (TKns) and near the contact of Darrington Phyllite (Ked). The units are described below.

Qf (Holocene): Poorly sorted cobble to boulder gravel, deposited either as a discrete lobe at the intersection of a steep stream with a valley floor of lower gradient or as a broad apron on steep sideslopes. Gradational with unit Qt (talus deposits of the Holocene), especially in granitic terrane where fans along major valleys commonly merge with talus. Mostly mapped from topography and aerial photos in alpine valleys. (Holocene)

TKns (Middle Eocene to Late Cretaceous): Predominantly fine-grained hornblende-mica schist, mica-quartz schist, hornblende schist, amphibolite, garnet-biotite schist, and minor hornblende-zoisite schist, hornblende garbenschiefer, calc-silicate achist, marble, and ultramafic rocks. In the Cascade River area and in the Straight Creek Fault zone, phyllitic muscovite-chlorite-quartz schist predominates. Rocks are mostly white, tan, brown to black, locally greenish with conspicuous compositional banding. Fine lamellar foliation, locally blastomylonitic. On outcrop scale the schist is isoclinally folded, commonly crenulated; small crinkle folds on prominent foliation surfaces.

Ked (Early Cretaceous): Silvery to black quartzose graphitic phyllite, with minor greenschist, metachert, and muscovite-quartz-albite schist. Commonly with multiple foliations and crenulation lineations; abundant quartz veins. Dominant foliation is commonly second generation or later.

Mineralogy is quartz-albite-white micachlorite, lawsonite, garnet, and margarite. Thin sections show well-crystallized white mica: fine grain size in hand sample reflects tendency of rock to break along post-peak metamorphic pressure-solution cleavage surfaces along which fine insoluble material has concentrated. Locally interlayered with unit Kes (Shuksan Greenschist of the Early Cretaceous).

Pcmv

Figure 3d: FDR 1050 MP 1.7 shown within geologic map excerpt

SITE CONDITIONS

Site photographs are provided as Attachment 1 as Photos 1 through 40.

FDR 3100 MP 6.7 (Approx. coordinates 48.941768° North Latitude, -121.941622° West Longitude)

Damage site photos appear in the attachment as Photos 1 through 8. The site is located within the fill slope above Canyon Creek, approximately 90 feet horizontal distance and 40 to 80 feet vertical distance (Measured with Google Earth and USGS Topographic maps, respectively). The embankment became saturated and failed during a storm event in the winter of 2015/2016. The damage extends about 10 feet into the traveled way, with length of approximately 120 feet.

The Forest Service, Region 6 & 10 Engineering, Geotechnical & Dam Services Office, Portland, OR, provided a Field Visit Memo dated March 14, 2016. The memorandum mentioned several areas of landslide instability in the general area. A limited investigation was performed consisting of several hand augers, two of which encountered a lacustrine silt layer. The memo described a “significant” spring in the cutslope above the failure that was estimated at 1-gallon per minute.

The memo reported the entire landslide escarpment to be saturated, with silty sand with gravel overlying lacustrine blue silt that was thought to be acting as an aquitard and perching water. The memo discussed undermining at the toe of the slope by Canyon Creek, which has subsequently migrated to the other side of the stream channel due to the landslide.

TKns

Ked

Kmd

Kes

During our reconnaissance in September 2016, we observed the embankment below the traveled way adjacent to the northeast of the main failure (about Station 313) had slumped about 4 to 6 feet, as shown in Photos 1 and 2. We observed a steep cutslope above the road that was noted to be wet at the base, indicating seepage or a possible spring, with hydrophilic plants present. The face of the failure appeared to be relatively dry. We noted that the Forest Service had placed rock in the ditch to gain width through the damaged zone, as shown in Photo 7 and 8.

FDR 3140 MP 0.5 (Approx. coordinates 48.948631° North Latitude, -121.940244° West Longitude)

Photos for this damage site appear in the attachment as Photos 9 through 17.

This site is located on the valley slope above Canyon Creek, approximately 700 feet horizontal distance and 280 feet vertical distance (measured with Google Earth and USGS Topographic maps, respectively).

There is a culvert at this site. Heavy rain saturated the banks and caused the local fill to slide. The culvert inlet became blocked (infilled), but we noted that it appears to have been in that condition for some time. Rock in the cutslope (possibly a bedrock outcrop) near the end of the failure above the culvert inlet was observed during our reconnaissance, as shown in Photos 11 and 12. The slope above the cut appeared to be hummocky, thus indicating likely historic instability. We noted a few boulders scattered throughout the site and an old tree stump (Photo 13) that was revealed following the embankment failure. A possible sloped outcropping of bedrock was noted in the face of the failure (Photo 14). The ditch was observed to be wet with seepage terminating at a void in the ground above the infilled culvert inlet as shown in Photos 9 and 15.

FDR 3900 MP 2.27 (Approx. coordinates 48.863630° north latitude, -121.903400° west longitude)

Damage site photos appear in the attachment as Photos 18 through 22.

The site is located on the eastern valley slope above Glacier Creek, approximately 300 feet horizontal distance and 160 feet vertical distance (measured with Google Earth and USGS Topographic maps, respectively). There is a culvert at this location that is located in-line with, and near the base of a drainage feature that channeled water and debris from the slope above during the storm event. The debris flow covered the road and blocked the inlet, but has since been cleared to allow vehicular passage. The debris consisted of soils, organics, cobbles and boulders. The embankment was scoured along the road for about 30 feet.

Our observations suggest that the fill slope below the road was armored with riprap prior to failure, as shown in Photos 20 and 22. Riprap up to 3 feet, or larger, was observed on the embankment slope.

The soils in the embankment appear to be predominantly granular consisting of silty, sandy gravel with cobbles.

FDR 1130 MP 4.1 & 1144 MP 0.1 (Approx. coordinates 48.764450° North Latitude, -121.672481°

West Longitude)

Damage site photos appear in the attachment as Photos 23 through 33.

Saturated soils failed, thus resulting in a debris flow and loss of ground between the 1130 (upslope) and 1144 (downslope) roads. The head of the failure is at the FDR 1130 road where it impacted approximately 10 feet along the traveled way, and reached about 4 feet into it. The toe of the debris flow extended well beyond the 1144 road after the culvert catch basin and ditch clogged and debris was transported over the road and onto the lower slope. We noted a large boulder and possible bedrock outcrop in the face of failure (Photo 30) and in the slope left of the base of the failure (not visible in the photo). We noted the toe of failure to be wet with active seeps and ponding, with seepage crossing the 1144 road (Photo 33). The slope below the 1144 road appeared to be stable.

The slope above the 1130 appeared to be hummocky with a possible draw that is not very well developed (Photo 27).

FDR 1050 MP 1.7 (Approx. coordinates 48.583050° North Latitude, -121.422070° West Longitude)

Damage site photos appear in the attachment as Photos 34 through 40.

There is an existing 6-foot diameter CMP culvert that became blocked and overwhelmed when storm-generated large debris was carried down the drainage channel during the storm event, filled in the channel, and overtopped and eroded the road. Scour occurred along the entire length of the culvert, thus washing away the road fill above the pipe and exposing the pipe profile for most of its length, as seen in the photos. The large debris consisting of timber and boulders is scattered throughout the upper and lower channels. Boulders are estimated up to 3 to 4 feet, but larger sizes may be present.

The channel was observed to be flowing during the site reconnaissance as seen in Photos 36 and 38.

In-situ fill soils at the culvert location appear to be predominantly granular.

SUBSURFACE CONDITIONS

The subsurface investigation for the project consisted of seven geotechnical test hole borings drilled by Geotek Alaska, Inc. in early-to-mid July, 2017. Approximate test hole locations are shown in

Figures 4a though 4c. The test holes were logged by WFLHD personnel at the time of drilling.

The test holes were advanced using a CME-75 truck-mounted drill rig using a 7.625 inch outside diameter (OD) hollow stem auger and/or a casing advancer system. NQ sized rock coring tools were used to obtain core samples when rock was encountered. Penetration tests, consisting of 2 inch OD split spoon Standard Penetration Tests (SPTs) or 3 inch OD Dames and Moore (D&M) split spoons, were performed at 2.5 foot intervals where possible. SPT samples were visually classified in the field and at the WFLHD office in Vancouver. Laboratory tests were performed on select samples for soil classification and/or index tests and appear in the discussions below. Water levels, when encountered, were recorded on the boring logs and are also contained in the following discussions.

Groundwater was encountered in several geotechnical borings and can be seen in the boring logs. It should be noted that these measurements during drilling operations were taken at a specific time of year. It is expected that groundwater levels will likely fluctuate with the time of year, rain, or snow events. No groundwater measuring instruments were installed as part of this geotechnical subsurface investigation.

FDR 3100 MP 6.7

Test hole boring B17-01 was drilled near the southeast edge of the main scarp (Photo 01) and

B17-02 was drilled near the northeast edge (Photos 01 & 02). B17-03 was drilled northeast of

B17-02 above the slumped ground described earlier and shown in Photo 03. The B17-01 boring was advanced to 27.5 feet below ground surface (bgs), B17-02 was advanced to 38 feet bgs, and B17-03 was advanced to 45 feet bgs. Laboratory tests were performed on select samples from each test hole. Approximate test hole locations are shown in Figure 4a. Soil profiles and subsurface conditions in each test hole boring are described below.

B17-01

• Encountered predominantly granular soils overlying bedrock (Greenstone).

• 0 to approximately 7.5 feet: Fill containing medium-dense, silty, clayey gravel with sand with cobbles or possible boulders noted at the bottom of the layer. Laboratory testing showed this material to classify as GC-GM in the Unified Soil Classification System (USCS) with a Liquid Limit (LL) of 24 and a Plasticity Index (PI) of 5 (slightly plastic).

• 7.5 feet (approx.) to Bottom of Hole (BOH): Bedrock (Greenstone), light grayish green, fine to medium grained, moderately weathered, weak to medium-strong in the upper portion and transitions to medium-strong with depth. Reported to be highly sheared with slickenslides and closely spaced, clay-coated discontinuities that transition to moderately spaced with depth. The discontinuities are reported to range from 15 to 80 degrees from assumed horizontal. Rock Quality Designation (RQD) ranged from 18 to 82 percent with

Core Recoveries (CR) of 90 to 96 percent.

• No groundwater was encountered prior to the introduction of drilling fluids.

B17-02

• 0 to 3.5 feet: Fill comprised of medium-dense, clayey sand with gravel

• 3.5 feet to 7.5: feet: very dense, poorly graded gravel with silty clay and sand (GP-GC) with a

LL of 24 and a PI of 7 (medium plastic).

• 7.5 feet to 10 feet: very dense, silty, clayey sand with gravel (SC-SM) with a LL of 23 and a

PI of 7 (medium plastic)

• 10 feet to 13 feet: very dense, well-graded, gravel with silt, sand, and cobbles.

• 13 feet to 22 feet: very dense silty, clayey sand with gravel (SC-SM) with a LL of 19 and PI of

5 (slightly plastic)

• 22 feet to BOH: Bedrock (Greenstone), dark, greenish-gray, fine to medium grained, slightly weathered, and medium-strong (R3), with quartz veins ranging in thickness from 1/16 inch to

¼ inch. Discontinuity spacing ranging from extremely-closely to moderately-closely, and in fair to good condition. Discontinuities range from about 20 to 60 degrees from assumed horizontal. RQD ranged from 0 to 66 percent with CR of 63 to 100 percent.

• Groundwater measured at 14 feet while drilling and at 16 feet following drilling.

B17-03

• Encountered predominantly granular soils overlying bedrock (Metaconglomerate and

Greenstone).

• 0 to 2.5 feet: Fill comprised of very loose to loose, well-graded sand with gravel

• 2.5 feet to 10 feet: Very loose to dense, non-plastic, silty sand with gravel (SM). At 7.5 feet moisture content changed to moist to wet.

• 10 feet to 20 feet: Moist to wet, medium-dense to very-dense, silty, clayey sand with gravel

(SC-SM) and cobbles, with a LL of 24 and PI of 7. (medium plastic)

• 20 feet to 28 feet: moist to wet, very dense, clayey gravel with sand (GC) and cobbles, with a LL of 25 and PI of 9 (medium plastic). Varying degrees of drilling resistance and grinding/chatter was reported within this zone.

• 28 feet to 33 feet: Bedrock (Metaconglomerate), dark, greenish-gray to dark gray, fine to very coarse-grained, slightly to moderately weathered, medium strong (R3). Discontinuities were reported as very-closely to closely spaced and in good condition. Discontinuities were measured at 70 to 80 degrees from assumed horizontal. No recovery reported between 30.0 to 33.1 feet bgs, possibly indicating a zone of completely weathered/residual soil. RQD ranged from 0 to 38 percent with recoveries of 0 to 77 percent.

• 33 feet to BOH: Bedrock (Greenstone), greenish-gray to dark-gray, fine to medium-grained, slightly to moderately weathered, medium-strong (R3). Discontinuities are very-closely to closely spaced and in fair to good condition. Discontinuities measured at 30 to

45 degrees from assumed horizontal. Veins of quartz up to ¾ inch thick were noted near the bottom of the boring. RQD ranges from 43 to 67 percent with CR of 93 to 100 percent.

• Groundwater was measured at 5.5 feet following drilling.

Figure 4a: Approximate test hole location at FDR 3100 MP 6.7

(Image captured from 7/2016 Google Earth imagery)

FDR 3140 MP 0.5

Test hole boring B17-04 was drilled near the southwest edge of the main scarp (Photo 16) and

B17-05 was drilled near the northeast edge (Photo 17). The B17-04 boring was advanced to 47.9 feet bgs and B17-05 was advanced to 64 feet bgs. Laboratory tests were performed on select samples from each test boring. Approximate test hole locations are shown in Figure 4b. Soil profiles and subsurface conditions at each test hole boring are described below.

B17-04

• 0 to 9.5 feet: Fill composed of very dense, poorly-graded gravel with sand.

• 9.5 feet to BOH: Bedrock (Greenstone), light-green to brown, fine grained, moderately weathered, strength varies from weak (R2) to medium-strong (R3), with quartz veins up to

¾ inch thick measured. Discontinuity spacings are extremely-closely to moderate, and range from fair to poor condition, and range from 0 to 75 degrees from assumed horizontal.

RQD from 0 to 74 percent with CR of 30 to 100 percent.

• Groundwater was not encountered in the boring.

B17-05

• Encountered predominantly granular soils over bedrock (Schist and Greenstone).

• 0 feet to 12.5 feet: Fill consisting of very dense, silty, clayey sand. Boulders were noted below 5 feet.

• 2.5 feet to 30 feet: Very-dense silty, clayey sand with gravel (SC-SM), with LL ranging from 18 to 19 and PI ranging between 4 and 5 (slightly plastic). Varying degrees of drill rig chatter was noted below 20 feet indicating cobbles and/or possible boulders.

• 30 feet to 45.7 feet: Schist bedrock, reddish-brown, fine-grained, fresh to slightly weathered and medium strong to strong (R3 to R4), containing quartz and/or calcite veins up to 1” thick. Discontinuities reported as very-closely to closely spaced and in poor to good condition, ranging from 5 to 80 degrees from assumed horizontal. At 45 feet bgs the drilling fluid started to become lost. RQD ranges from 0 to 27 percent with CR of 71 to 94 percent.

• 45.7 feet to BOH: Bedrock (Greenstone), green, fine-grained, slightly to moderately weathered, weak to medium-strong (R2 to R3). Discontinuities are very-closely to closely spaced and in fair to poor condition, ranging from 10 to 90 degrees from the assumed horizontal. RQD reported at 0 percent throughout this zone with CR of 33 to 100 percent.

• Groundwater was not encountered in the test hole.

Figure 4b: Approximate test hole location at FDR 3140 MP 0.5

Test hole boring B17-06 was drilled approximately 8 feet behind the top of the main scarp on the

1130 Road (Photo 32) and B17-07 was drilled in the middle of the 1144 Road at the base of the failure (Photo 33). The B17-06 boring was advanced to 63.3 feet bgs and B17-07 was advanced to

29 feet bgs. Laboratory tests were performed on select samples from the B17-06 test hole. Samples from the B17-17 test hole were not tested. Approximate test hole locations are shown in Figure 4c.

Soil profiles and subsurface conditions at each test boring are described below.

B17-06

• 0 to 7 feet: Fill comprised of very loose, well-graded gravel with silt and sand. Laboratory testing showed this material to classify as GW-GM in the USCS with a LL of 24 and PI of 5

(slightly plastic).

• 7 feet to 10 feet: Very-dense, silty gravel with sand and some cobbles.

• 10 feet to 12.5 feet: Very-dense, clayey sand with gravel, cobbles, and boulders.

• 12.5 to 20.0 feet: Very-dense, non-plastic, silty sand (SM) with gravel, cobbles, and boulders.

• 20 to 23 feet: Very-dense, clayey sand with gravel, cobbles, and boulders.

• 23 to 45 feet: Wet, very-dense, non-plastic, poorly graded sand with silt and gravel (SP-SM) and cobbles.

• 45 feet (approx.) to BOH: Bedrock (Greenstone), fine to medium grained, slightly to moderately weathered, strong (R4), includes lenses of serpentine. Discontinuities measured at extremely-closely spaced, in fair to good condition, and at 70 to 90 degrees from assumed horizontal. RQD reported at 0 percent with CR of 100 percent (although the first approximately 10 feet were augured and not cored).

• Groundwater measured while drilling reported at 23 feet bgs, but water circulation was reported lost below 57 feet, possibly indicating open fractures below that depth.

B17-07

• Encountered a thin clay layer and primarily granular soils overlying bedrock (Greenstone).

• 0 feet to 5 feet: Fill comprised of very loose, well-graded gravel with sand.

• 5 feet to 6 feet: Wet, soft, sandy, silty clay of low plasticity.

• 6 feet to 7.5 feet: Wet, dense, clayey gravel with sand.

• 7.5 feet to 15 feet: Wet, medium-dense, silty gravel with sand. At 12.5 feet bgs sand lenses were noted. This zone interpreted as completely weathered/residual soil.

• 15 feet to BOH: Bedrock (Greenstone), fine to medium-grained, slightly to moderately weathered, medium strong to strong (R3 to R4). Discontinuities are extremely-closely-spaced to closely-spaced and in fair to good condition, at 45 to 90 degrees from assumed horizontal.

RQD reported at 0 percent to 32 percent with CR of 91 to 100 percent.

• Groundwater was encountered at 4 feet during drilling.

Figure 4c: Approximate test hole location at FDR 1130 MP 4.0 & FDR 1144 MP 0.1

FDR 1050 MP 1.7 & FDR 3900 MP 2.27

Subsurface investigations were not conducted at these two repair sites.

ANALYSIS

Except for performing the site reconnaissance, determining subsurface conditions, recommendation of bearing capacity, and the selection of the recommended option (discussed below), additional geotechnical design analyses were not deemed necessary for the project given the level of damage at the sites, the scope of the ERFO program, and our prior experience with similar storm damage in the region. Designs are based on WFLHD standard ERFO design templates and recommendations for the appropriate repairs as discussed below.

DESIGN RECOMMENDATIONS

FDR 3100 MP 6.7, FDR 3140 MP 0.5, FDR 3900 MP 2.27 & FDR 1130 MP 4.1 & 1144 MP 0.1

A Reinforced Soil Slope (RSS), Mechanically Stabilized Earth (MSE) Wall, and Special Rock

Embankment (SRE) were all considered as potential options for repairing these sites. However, due to lower cost and reduced construction time, a SRE is recommended as the preferred option.

A SRE can be constructed as steep as 1:1 to reduce material quantities if reinforcements are used. In this case, it is referred to as a reinforced SRE.

A reinforced SRE consists of placing alternating layers of reinforcement and mechanically placed rock that is benched into the existing slope with a maximum slope face ratio of 1:1 and a geotextile separation fabric placed behind and below the SRE. The SRE may be constructed flatter than 1:1;

however, reinforcements are still required for slope steepness up to 1:1.25 (V:H). Anything flatter than 1:1.25 can be constructed unreinforced. A conceptual illustration of a reinforced SRE is shown in Figure 5. The proposed reinforced SRE for the project repair sites are designed to be constructed at 1:1.25 maximum steepness. At the time of this memo, the anticipated maximum design heights for the reinforced SREs at these repair sites range from 22 to 48 feet. Refer to the final contract plan set for specific design requirements.

Figure 5: Conceptual illustration of a reinforced SRE at 2700 MP 6.9

Additional information provided in the FS memo discussed under Site Conditions for the FSR 3100

MP 6.7 site was the recommendation for subsurface drainage upslope of the failure and for surface drainage improvements. Subsurface drainage was considered during project development for the cutslope above FDR 3100 MP 6.7; however, it was determined that this type of mitigation was outside the scope of the ERFO program to reestablish the road to its original condition, and consequently dropped from further consideration based on that criteria. Surface drainage additions are planned for this location with the installation of two culverts outside of the failure zone and the removal of the existing culvert.

A proposed AOP box culvert was designed by the WFLHD Hydraulics Team for this repair site as presented in Aquatic Organism Passage Hydraulics Report, dated December 18, 2017. The proposed culvert is approximately 18 feet by 17 feet. We provided the Hydraulics Team recommended factored bearing pressure of 5 tons per square foot (tsf) for this location in an email dated September 27, 2017.

Refer to the contract documents for specific design requirements pertaining to the AOP box culvert.

CONSTRUCTION CONSIDERATIONS

FDR 3100 MP 6.7 (Photos 1 through 8)

A reinforced special rock embankment (SRE), as shown in the conceptual illustration appearing in

Figure 5, is the proposed repair for this damage site. The preliminary plans call for a maximum height of approximately 26 feet. Refer to the final contract plan set for specific design requirements.

The site is located within a narrow corridor of the FDR 3100 bounded by steep slopes. The existing damage at this site reaches about 10 feet into the travel way; however, the ditch has been temporarily filled in to allow vehicular passage, as can be seen in Photo 1, but might impact construction logistics.

Seeps were noted in the cutslope above the failure and within the escarpment during the site reconnaissance performed in March 2016 and September 2016. Groundwater was encountered at

16 feet and 5.5 feet in B17-02 and B17-03, respectively, located near the end of the repair zone, in early July 2017. Groundwater was not encountered in test boring B17-01, located near the beginning of the repair zone.

Wet conditions may impact construction efforts, including allowable benching heights, temporary cutslope ratios and time allowed for the excavation to be open. We recommend construction at this site commence during the dry season (late July to mid-August) when seepage activity is expected to be to be at a minimum and to provide increased stability of the cut during construction.

The three test hole borings encountered bedrock at various elevations, indicating that bedrock contacts should be expected to be irregular. The Contractor must be prepared to excavate into, and handle, weak to medium-strong bedrock (R2 to R3) with RQD that varies from 0 to 82. If the foundation of the SRE is in bedrock, it is likely that the bench widths can be reduced. Work with and seek approval from the CO for potential bench width reductions.

FDR 3140 MP 0.5 (Photos 9 through 17)

A reinforced SRE is the proposed repair for this site. The preliminary plans call for a SRE with maximum height of approximately 37 feet. Refer to the final contract plan set for specific design requirements. Like the FDR 3100 MP 6.7 site, this repair is located within a narrow corridor bounded by steep slopes and construction logistics must be considered.

Both of test hole borings at this location encountered bedrock at differing elevations, indicating that the bedrock contacts are likely to be irregular. Boulder or possible boulders were noted in the boring logs. Possible bedrock was noted in the cutslope and lower in the face of the failure. The contractor must be prepared to excavate into, and handle, weak (R2) to strong (R4) rock with RQD of 0 to 75 percent and boulders of unknown size. If the foundation of the SRE is in bedrock, it is likely that the bench widths can be reduced. Work with and seek approval from the CO for potential bench width reductions.

FDR 3900 MP 2.27 (Photos 18 through 22)

Preliminary plans call for a reinforced SRE at this repair site. At the time of this memorandum the planned maximum height of the reinforced SRE is approximately 22 feet. The preliminary plans call for cleaning the drainage structure without replacement. Refer to the final contract plan set for specific design requirements.

We did not perform a geotechnical investigation at this damage site. The observed soils appear to be predominantly granular. Riprap up to 3 feet in diameter, or larger, was observed on the embankment slope. Boulders were not observed in the face of the failure during our reconnaissance, but encountering them in the excavation should not be ruled out. The Contractor should be prepared to handle large boulders.

FDR 1130 MP 4.1 & 1144 MP 0.1 (Photos 23 through 33)

The preliminary plans call for a SRE with a maximum height of approximately 48 feet. Refer to the final contract plan set for final design requirements.

Two test holes were drilled on the two roads within the narrow corridors of this damage site. A steep slope separates the two roads. B17-06 was drilled on the FDR 1130 (upper road) and B17-07 was drilled on FDR 1144 (lower road). Bedrock was encountered in B17-06 at 45 feet bgs and at 15 feet bgs in B17-07. We noted the appearance of a possible boulder and possible bedrock outcrop within the face of the failure as shown in Photo 30. As with the previous sites, it is not unusual for bedrock to have highly irregular contact surfaces. The Contractor should be prepared to encounter and excavate into strong bedrock (R4) with RQD of 0 to 32 percent, or possibly higher, and handle boulders of unknown size. Of note is that the bedrock, when encountered in the B17-06 test hole, was augured for at least the first 10 feet. If the foundation of the SRE is in bedrock, it is likely that the bench widths can be reduced. Work with and seek approval from the CO for potential bench width reductions.

The toe of failure was observed to be wet during the reconnaissance (June 2017) with active seeps and a little ponding water that crossed FDR 1144. Wet conditions may impact construction efforts, including allowable benching heights, temporary cutslope ratios and time allowed for the excavation to be open. We recommend construction at this site commence during the dry season (late July to mid-August) when seepage activity is expected to be to be at a minimum and to provide increased stability of the cut during construction.

FDR 1050 MP 1.7 (Photos 34 through 40)

Preliminary plans call for a 18 feet by 17 feet AOP box culvert box for this repair site. Large debris consisting of timber and boulders is scattered throughout the upper and lower channels of this repair site. The Contractor must be prepared to handle boulders that were estimated up to 3 to 4 feet diameter, and possibly larger. The fill materials used in the original construction appear to be predominantly granular.

REFERENCES

• Google Earth

• Geologic Map of the Mount Baker 30- by 60-Minute Quadrangle, Washington by R.W. Tabor, R.A. Haugerud, Wes Hildreth, and E.H. Brown, USGS, 2003.

• Aquatic Organism Passage Hydraulics Report, USDOT FHWA, December 18, 2017.

• Field Visit Memo, USFS, Region 6 & 10 Engineering, Geotechnical & Dam Services Office, Portland, OR, dated March 14, 2016

CLOSING

This memorandum was prepared to provide observations made during site reconnaissance, the subsurface investigation results, and geotechnical recommendations for the Mount Baker Emergency

Repairs 2016 project on FDR 3100 at MP 6.7, FDR 3140 at MP 0.5, FDR 3900 at MP 2.27, FDR

1130 at MP 0.1 and FDR 1144 MP 4.1, and FDR 1050 at MP 1.7 in Mt. Baker-Snoqualmie National

Forest, WA. Professional judgments and recommendations are presented in this memorandum.

They are based partly on evaluation of the technical information gathered and partly on the WFLHD

Geotechnical Team’s general experience with subsurface and other conditions in the region. It should be noted the explorations, where performed, might not represent potentially unfavorable subsurface conditions beyond the immediate location of the exploration. The observed water levels, and/or conditions indicated on the boring logs are as recorded at the time of the exploration. The water levels and/or conditions may vary considerably, with time, according to the climate, rainfall, and other factors.

During construction, if subsurface conditions are encountered that vary from those discussed in this memorandum, or if design loads, project stationing, and/or configurations change, the WFLHD

Geotechnical Team should be notified immediately to evaluate what effects, if any, the changes have on the recommendations contained herein. The recommendations presented in this memorandum are applicable only to this specific project as described. These data are not to be used for other purposes.

Please contact Robert Kraig at (360) 619-7699 or robert.kraig@dot.gov with any questions regarding this memorandum.

RK

CC: Betty Chon

Nathan Jenks

Rodney Meadows

Jennifer Chariarse mailto:robert.kraig@dot.gov

Carolyn Sourek

Benn Oltmann

Mike Baron

Stephen Henry

Geotechnical File

Attachments:

1. Site Photos

2. Subsurface Investigation Results

Attachment 1

Site Photographs

(Intentionally blank)

FDR 3100 MP 6.7

Photo 1: Looking back online.

Photo 2: Looking back onto the failure face. Note slumped embankment.

Area of slumped embankment

Photo 3: Toe of landslide.

Photo 4: Looking ahead through corridor.

Photo 5: Looking ahead at failure face.

Photo 6: Location of B17-01 (B17-02 also indicated).

B17-01

6/14/2017

Photo 7: Location of B17-02.

Photo 8: Location of B17-03.

B17-03

Forest Service placed rock

Forest Service place rock

FDR 3140 MP 0.5

Photo 9: Looking back through site corridor.

Photo 10: Looking back at failure.

Wet ditch

Photo 11: Cutslope above culvert inlet. Note possible bedrock outcrop.

Photo 12: Cutslope above culvert inlet. Note possible bedrock outcrop.

Possible bedrock outcrop

Possible bedrock

Photo 13: Old tree stump revealed following failure.

Photo 14: Possible bedrock outcrop near toe.

Old tree stump

Possible bedrock

Photo 15: Infilled inlet.

Photo 16: Location of B17-04.

B17-04

Infilled culvert inlet

Photo 17: Location of B17-05.

FDR 3900 MP 2.27

Photo 18: Looking ahead across damage site.

B17-05

Photo 19: Looking back through damage site.

Photo 20: Note possible riprap slope protection.

Possible riprap slope armor prior to failure

Photo 21: Looking back over failure area.

Photo 22: Note possible riprap slope protection.

Possible riprap slope armor prior to failure

Photo 23: FDR 1130 looking back online.

Photo 24: FDR 1130 looking back at head of failure.

Photo 25: FDR 1130 looking ahead at failure.

Photo 26: Looking down to FDR 1144 from FDR 1130.

Photo 27: Possible hummocky ground. Note possible drainage channel developing.

Photo 28: FDR 1144 looking ahead a toe of repair zone.

Possible drainage path developing

Photo 29: FDR 1144 slope below road.

Photo 30: Looking up the face of the failure to the 1130 road.

Note large boulders and possible bedrock outcrop.

Possible bedrock

Large boulder

Large boulder

Photo 31: Toe of failure above the FDR 1144.

Photo 32: Location of B17-06 on the FDR 1130 Road.

B17-06

Photo 33: Location of B17-07 on the 1144 Road.

Photo 34: Looking ahead.

B17-07

Photo 35: Looking ahead at existing culvert outlet.

Photo 36: Inlet side. Note active flow.

Photo 37: Looking back.

Photo 38: Culvert outlet. Note outflow and boulders present.

Photo 39: Culvert inlet. Note debris.

Photo 40: Drainage channel leading in to culvert inlet. Note boulders.

Attachment 2

Field Classifications for Soil and Rock Unified Soil Classification System

Soil Descriptive Terminology Rock Descriptive Terms

Boring Logs Soils Test Reports

SOIL DESCRIPTIVE TERMINOLOGY

CONSISTENCY OF COHESIVE SOILS

SPT N-Value (blows/ft) Consistency Field Identification

0 - 1 Very Soft Easily penetrated several inches by first

2 - 4 Soft Easily penetrated several inches by thumb

5 - 8 Firm Moderate effort required to penetrate several inches by thumb

9 - 15 Stiff Readily indented by thumb but penetrated only with great effort

16 - 30 Very Stiff Readily indented by thumbnail

> 30 Hard Indented with difficulty by thumbnail

RELATIVE DENSITY OF

COHESIONLESS SOILS

SPT N-Value (blows/ft) Relative Density

0 - 4 Very Loose

5 - 10 Loose

11 - 30 Medium Dense

31 - 50 Dense

> 50 Very Dense

PARTICLE SIZE

Term Sieve Size

Boulder > 12” (>300mm)

Cobble 3” - 12” (75mm - 300mm)

Gravel – coarse ¾” - 3” (19mm - 75mm)

Gravel – fine #4 - ¾” (4.75mm - 19mm)

Sand – coarse #10 - #4 (2.00mm - 4.75mm)

Sand – medium #40 - #10 (0.425mm - 2.00mm)

Sand – fine #200 - #40 (0.075mm - 0.425mm)

Silt & Clay < #200 (<0.075mm)

MOISTURE CONTENT

Dry Dusty, dry to the touch

Moist Damp, but no visible free water

Wet Visible free water, saturated, over optimum

ROCK DESCRIPTIVE TERMS

ROCK WEATHERING

Field Identification Term Crystals are bright. Discontinuities may show some minor surface staining.

No discoloration in rock fabric. Fresh

Rock mass is generally fresh. Discontinuities are stained and may contain clay. Some discoloration in rock fabric.

Slightly Weathered

Significant portions of rock show discoloration and weathering effects.

Crystals are dull and show visible chemical alteration. Discontinuities are stained and may contain secondary mineral deposits.

Moderately Weathered

Rock can be excavated with geologist’s pick. All discontinuities exhibit secondary mineralization. Complete discoloration of rock fabric. Surface of core is friable and usually pitted due to washing out of highly altered minerals by drilling water.

Highly Weathered

Rock mass is completely decomposed. Original rock “fabric” may be evident. May be reduced to soil with hand pressure. Decomposed

DISCONTINUITY SPACING ROCK QUALITY DESIGNATION (RQD)

Spacing (in) Spacing Term RQD % Designation < 2.5 Very Close 0 - 25 Very poor

2.5 – 8 Close 25 - 50 Poor 8 – 24 Moderately close 50 - 75 Fair 24 – 80 Wide 75 - 90 Good

> 80 Very Wide 90 - 100 Excellent (RQD is the percent of a core run with intact lengths greater than 4 inches excluding breaks caused by drilling.)

INTACT ROCK STRENGTH

Field Identification UCS (psi) Hardness Term Indented by thumbnail. 35 - 150 Extremely Weak (R0) Crumbles under firm blows with point of geological hammer, can be peeled by a pocket knife. 150 - 725 Very Weak (R1)

Can be peeled by a pocket knife with difficulty, shallow indentations made by firm blow with geological hammer.

725 – 3,500 Weak (R2)

Cannot be scraped or peeled with a pocket knife, specimen can be fractured with a single blow of geological hammer.

3,500 – 7,000 Medium Strong (R3)

Specimen requires more than one blow of geological hammer to fracture it. 7,000 – 15,000 Strong (R4)

Specimen requires many blows of geological hammer to fracture it. 15,000 – 36,000 Very Strong (R5)

Specimen can only be chipped with geological hammer. > 36,000 Extremely Strong (R6) (UCS – Unconfined Compressive Strength)

Rec. = 90%

RQD = 18%

Rec. = 96%

RQD = 82%

Rec. = 94%

RQD = 54%

3-8-16 (14" = 78%)

15-35-33 (18" = 100%)

50/2 (0" = 0%)

50/1 (0" = 0%)

50/0 (0" = 0%)

S01

S02

S03

S04

S05

R1

R2

R3

ASPHALT, 3.5" thick Silty, clayey GRAVEL with sand, medium dense, dark grayish brown to light brown, moist. Sand is mostly medium to coarse, angular to subangular, fine to coarse gravel, trace organics in upper 0.51, clasts up to 1.5" in diameter. FILL.

At 5', clay in upper 0.5 foot of sample, cobbles.

At 7.5', no sample recovery, cobbles and possible boulders.

GREENSTONE, light grayish green, fine to medium grained, moderately weathered, weak to medium-strong (R2 to R3), highly sheared with slickenslides and clay coated discontinuities, calcite veins. Discontinuities are closely spaced and in poor condition, FF = 4, RCT = 17 minutes 15 seconds, discontinuities range from 15 to 80 degrees from assumed horizontal.

Run 2: Medium strong (R3). Discontinuities are closely to moderately spaced and in fair to poor condition, FF = 1, RCT = 8 minutes 30 seconds.

Run 3: Medium strong (R3). Discontinuities are moderately spaced, FF = 3, RCT = 11 minutes 20 seconds.

Bottom of Boring at 27.5'

No groundwater encountered prior to the introduction of drilling fluids.

0.3

10.0

27.5

RECOVERY (%)

0 50

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 48° 56' 29.87" (48.94163°)

LONGITUDE (DEGREES): W 121° 56' 30.37" (121.94177°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 27.5'

LIQUID LIMIT

RQD (%)

AFTER DRILLING

Casing Advancer

NQ Rock Core

2" OD Split Spoon (SPT)

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

Casing Advancer to 12.5', NQ Core below 12.5'.

3100 MP 6.7

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

Logs were observed in the road fill in the failure surface.NOTES:

BORING B17-01

COMPANY:

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Geotek Alaska LOGGER: O. George

Mostly Cloudy

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

James Beckner

WEATHER:

PROJECT: WA ERFO 2016 (1), WA ERFO 2016(2), WA ERFO 2016(3)

Automatic

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/10/2017

S A

M P

LE

R

7/10/2017

STATION, OFFSET:

PLASTIC LIMIT

Rec. = 100%

RQD = 44%

Rec. = 63%

RQD = 0%

Rec. = 95%

RQD = 57%

Rec. = 100%

RQD = 66%

3-12-5 (6" = 33%)

38-39-40 (18" = 100%)

7-36-33 (18" = 100%)

47-50/3 (8" = 89%)

24-50/4.5 (10" = 93%)

33-50/3.5 (8" = 83%)

50/2 (0" = 0%)

50/1 (0" = 0%)

S1

S2

S3

S4

S5

S6

S7

S8

R1

R2

R3

R4

GRAVEL AND COBBLES, 2" thick.

Clayey SAND with gravel, medium dense, black to brown, moist, medium sand, subrounded to subangular, fine to coarse gravel, trace organics. FILL.

Poorly-graded GRAVEL with silty clay and sand (GP-GC), very dense, brown, moist, fine to coarse gravel, subangular to angular, medium sand.

Silty, clayey SAND with gravel (SC-SM), very dense, brown, moist, medium to coarse sand, subangular to subrounded, fine to coarse gravel.

Well-graded GRAVEL with silt, sand, and cobbles, very dense, brown to gray, moist, fine to coarse gravel, subrounded to subangular, medium sand.

Auger refusal at 131 on cobble. Switch to air hammer casing advancer.

Silty, clayey SAND with gravel (SC-SM) and cobbles, very dense, brown to gray, moist to wet, medium sand, subrounded to subangular, fine to coarse gravel.

GREENSTONE, dark greenish gray, fine to medium grained, slightly weathered, medium strong (R3), veins of quartz ranging with thickness ranging from 1/16" 1/4".

Discontinuities are very closely to closely spaced and in fair to good condition, FF = 1, RCT = 15 minutes 3 seconds, discontinuities range from 30 to 45 degrees from assumed horizontal.

Run 2: Discontinuities are extremely closely to very closely spaced, FF = 10, RCT = 22 minutes 9 seconds.

Run 3: Quartz veins with thickness of up to 1/2".

Discontinuities are very closely to moderately spaced and are in good condition, FF = 1, RCT = 6 minutes 46 seconds, discontinuities range from 20 to 30 degrees from assumed horizontal.

Run 4: Dark red staining. Discontinuities are in fair to good condition, FF = 1.3, RCT = 14 minutes 2 seconds, discontinuities range from 45 to 60 degrees from assumed horizontal.

Bottom of Boring at 38'

0.2

3.5

7.5

10.0

13.0

22.0

38.0

RECOVERY (%)

0 50

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 48° 56' 30.52" (48.941812°)

LONGITUDE (DEGREES): W -121° 56' 29.76" (-121.941599°)

D E

P T

H ft

Sheet 1 of 1

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 35'

LIQUID LIMIT

RQD (%)

AFTER DRILLING

Casing Advancer

2" OD Split Spoon (SPT)3" OD Split Spoon (D&M)

Hollow Stem Auger

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

Hollow Stem Auger to 13', Casing Advancer from 13' to 22.5' , NQ Core below 22.5'

3100 MP 6.7

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

13 feet from failure surfaceNOTES:

BORING B17-02

COMPANY:

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NQ Rock Core

Geotek Alaska LOGGER: N. Farny

Clear, 60° F

DATE STARTED:

0.0

FEDERAL HIGHWAY ADMINISTRATION

VANCOUVER, WASHINGTON

GEOTECHNICAL SECTION

James Beckner

WEATHER:

16'

PROJECT: WA ERFO 2016 (1), WA ERFO 2016(2), WA ERFO 2016(3)

Automatic

14'

WATER LEVELS

HAMMER:

WHILE DRILLING

DRILLER:

DRILL: CME-75

D E

P T

H ft

7/9/2017

S A

M P

LE

R

7/9/2017

STATION, OFFSET:

PLASTIC LIMIT

Rec. = 77%

RQD = 38%

Rec. = 0%

RQD = 0%

Rec. = 98%

RQD = 67%

3-2-1 (4" = 22%)

1-1-2 (8" = 44%)

8-26-18 (6" = 33%)

0-6-10-8 (14" = 58%)

2-2-2 (6" = 33%)

50/4 (4" = 100%)

6-33-50/6 (8" = 44%)

50/6 (6" = 100%)

S1

S2

S3

S4

S5

S6

S7

S8

S9

R1

R2

R3

ASPHALT, 3.5" thick Well-graded SAND with gravel, dark gray, moist, medium sand, subangular to subrounded, fine to coarse gravel.

FILL.

Silty SAND with gravel (SM), very loose, brown, moist, medium sand, subrounded to subangular, fine to coarse gravel.

Below 5', increased sand content.

At 7.5', dense, moist to wet, 3" diameter cobble in sample.

Silty, clayey SAND with gravel (SC-SM) and cobbles, medium dense, brown, moist to wet, medium to coarse sand, subrounded to subangular, fine to coarse gravel.

At 12.5', very loose.

At 15', very dense, cobble stuck in sampler tip.

Drill rig grinding and chatter below 18.51.

Clayey GRAVEL with sand (GC) and cobbles, very dense, gray, moist to wet, fine to coarse gravel, subrounded to subangular, medium to coarse sand.

Drilling resistance and grinding/chatter increases below 21'.

Drilling resistance and grinding/chatter decreases below 23.5'.

Drilling resistance and grinding/chatter increases below 26'.

Drilling rate decreases significantly below 26.5'.

Auger refusal at 27'. Switch to air hammer casing advancer.

METACONGLOMERATE, dark greenish gray to dark gray, fine to very coarse grained, slightly to moderately weathered, medium strong (R3), rounded clasts up to 2" in diameter. Discontinuities are very closely to closely spaced and in good condition, FF = 1.5, RCT = 7 minutes 8 seconds, discontinuities range from 70 to 80 degrees from assumed horizontal.

Run 2: No recovery from 30.3 to 33.1. Cuttings are gray medium to coarse sand with dark greenish gray rock chips.

Possible zone of highly weathered metaconglomerate that was washed away by drilling fluids.

GREENSTONE, greenish gray to dark gray, fine to medium grained, slightly to moderately weathered, medium strong (R3). Discontinuities are very closely to closely spaced and are in fair to good condition, FF = 1.2, RCT = 8 minutes 56 seconds, discontinuities range from 30 to 45 degrees from assumed horizontal.

0.3

2.5

10.0

20.0

28.0

33.0

RECOVERY (%)

0 50

FIELD "N" VALUE

FIELD

BLOW

COUNT

(Recovery)

LATITUDE (DEGREES): N 48° 56' 30.74" (48.941871°)

LONGITUDE (DEGREES): W -121° 56' 29.55" (-121.941543°)

D E

P T

H ft

Sheet 1 of 2

BORING LOG (US Customary Units)

S A

M P

LE

DRILLING METHODS:

DATE FINISHED:

TOTAL DEPTH: 45'

LIQUID LIMIT

RQD (%)

AFTER DRILLING

Casing Advancer

NQ Rock Core3" OD Split Spoon (D&M)

Grab Sample

AT COMPLETION

G R

A P

H

IC

L O

G

DESCRIPTION

Hollow Stem Auger to 27', Casing Advancer from 27' to 28', NQ Core below 28'

3100 MP 6.7

0.0

4.0

8.0

12.0

16.0

20.0

24.0

28.0

32.0

36.0

40.0

4…