Lorenz Gulch Geotechnical Investigation Trinity River

LORENZ GULCH GEOTECHNICAL INVESTIGATION

TRINITY RIVER RIVER MILE 89.4 to 90.2 TRINITY COUNTY, CALIFORNIA

Prepared for: U.S. Bureau of Reclamation Trinity River Restoration Program 1313 South Main Street Weaverville, CA 96093

and

Yurok Tribal Fisheries Department 190 Klamath Way Klamath, CA 95548

Prepared by: Rocco Fiori, PG 8066 Fiori GeoSciences PO Box 387 Klamath, CA 95548

February 2011

INTRODUCTION A geotechnical investigation was conducted within the Lorenz Gulch restoration site (Figure 1) to characterize geologic materials, depth to bedrock, and surface water and groundwater conditions. Additional analysis and interpretation was conducted to evaluate the thickness of alluvium and depth to bedrock at a proposed Engineered Log Jam (ELJ) site at river mile 89.68. This information was needed to inform river restoration designers and contractors of conditions that may affect the constructability and outcome of proposed river restoration designs.

Lorenz Gulch Project Location

Figure 1. General location map of the Lorenz Gulch Restoration Site, Trinity River near Douglas City, California. . LOCATION and BACKGROUND The Lorenz Gulch restoration site is located west of Steiner Flat Road, downstream of the Steiner Flat primitive campground and Douglas City (Figure 1). The restoration site extends from Trinity River mile 89.4 to 90.2 and covers both banks of the River. In 2010, the Yurok Tribal Fisheries Program was contracted by the Trinity River Restoration Program (TRRP) to design one of the Phase II channel restoration sites with construction anticipated to occur during the summer of 2012.

SITE GEOLOGY Large scale mapping (1:50,000 scale) by Irwin (2009) shows the Lorenz Gulch Environmental Study Limits (ESL) is underlain by Quaternary alluvium (Qal) and Bragdon Formation rocks of the Mississippian sub‐period. Bragdon Formation rocks are comprised of mudstones, sandstone and conglomerates and are part of the Eastern Klamath Terrane. However, bedrock exposures evaluated during this investigation identified the majority of the bedrock within project area as graphitic schist. This rock type is more likely Abrams Mica Schist (Dms) of the Devonian period and part of the Central Metamorphic Terrane. While Irwin’s (2009) map indicates the Bragdon Formation and Abrams Mica Schist is in fault contact in the Lorenz Gulch vicinity, it’s possible that the schist outcrops identified in the field were not observed at Irwin’s mapping scale.

APPROACH This geotechnical investigation was conducted in three parts: 1) characterization of surface and subsurface geologic conditions; 2) review of existing reports and datasets; and 3) a geophysical seismic refraction survey. The results of this report incorporate information obtained from all three aspects of this investigation. Characterization of surface and subsurface geologic conditions included: i) logging of test pits and trenches excavated at selected locations at the Lorenz Gulch ESL; ii) measurement of groundwater levels at peizometers installed within a subset of the excavation sites; and iii) a total station survey to tie key features to a common horizontal and vertical datum to allow spatial analysis of the associated data. Test pits and trenches were excavated August 9th and 10th 2010, with a 321B Caterpillar Excavator operated by Dwayne Proctor of the Yurok Tribe Watershed Restoration Department. Test pit logging and groundwater measurements were conducted by Rocco Fiori of Fiori GeoSciences (FGS) and David Bandrowski, Trinity Restoration Program (TRRP). Constrained by time, test pits on the right bank were primarily dug in an effort to locate bedrock and therefore geologic logs were not recorded. A total station survey of key features was conducted by Tony O’Rourke of Trinity Valley Consulting Engineers (TVCE) and tied to benchmarks established by the California Department of Water Resources (CDWR). Ground surface profiles were derived from LiDAR digital terrane model (DTM) prepared by Woolpert (2009). Due to time constraints and the availability of the LiDAR DTM, total station based cross‐section and longitudinal profile surveys were not conducted. Appendix A provides the geotechnical test pit logs prepared as part of this investigation. Appendix B provides the NORCAL Geophysical Consultants report for the seismic refraction survey.

RESULTS and DISCUSSION Geologic materials were characterized within fourteen test pits and groundwater measurements were taken at peizometers installed at a subset of eight pits with complementary water surface elevations surveyed at the river edge (Figure 2 and Table 1). Most of the alluvial materials described in the test pits appeared to be fluvially deposited, consistent with the geomorphic setting, and were comprised of coarse gravels, sands and silts (Table 1 and Appendix A). Although, Brandt Gutermuth (TRRP) considered the clean sand unit (SP) located at the base of LB9 may be from historic dredge operations at the site. A sample of this material was taken for further evaluation. Bedrock was encountered at shallow depths in three of the left bank test pits (with Map ID of LB1 at 3 ft., LB8 at 7 ft., and LB9 at 10 ft.). During excavation groundwater quickly equilibrated to levels within a few feet of the ground surface in most of the pits. The exceptions were at the pits where bedrock (LB1 and LB2) or thick alluvium (LB4, LB7 and LB8) limited the ability to excavate to the elevation of water bearing alluvium. Comparison of the river water‐surface elevations with groundwater elevations indicates the river had both gaining and losing reaches within the Lorenz Gulch ESL during the measurement period (Table 1 and Figure 3). NORCAL’s (2010) seismic survey indicated that in‐stream alluvium was likely to be < 10 ft. thick at the location of the proposed ELJ (Appendix B). Seismic velocities at depth were found to be consistent with a harder bedrock type of the mica schist found in field exposures; rather than softer sedimentary rocks indicated by Irwin’s (2009) mapping. Refer to appendix B for additional details from NORCAL’s (2010) seismic survey.

A comparison of NORCAL’s (2010) estimate for the thickness of in‐stream alluvium and depth to bedrock at the ELJ site with adjacent test pits is provided in figures 3 and 4. Based on NORCAL’s (2010) estimate, bedrock was about 2 to 3 feet below the depth of pit LB5 at an elevation of approximately 1548 feet.

Figure 2. Project location map of the Lorenz Gulch Restoration Site, Trinity River near Douglas City, California. Test pit sites are referenced in the text according to their Map ID as shown in table 1 and figure 2. Table 1. Summary of subsurface geotechnical conditions at the Lorenz Gulch exploration pits. Groundwater and river surface water elevations measured on 08‐10‐2010 by David Bandrowski. Test pit sites are referenced in the text according to their Map ID as shown in table 1 and figure 2. River Relative Pit Feature Groundwater Depth to USCS Material Map ID Feature Water Water Number Elevation Elevation Bedrock Classes Present Elevation Level RB1 RB1 Pit with no Obs Well 1,563.86 - - - NA GW RB2 RB2 Pit at Well Head 1,567.16 1,561.62 1,561.55 -0.07 NA GW RB3 RB3 Pit at Well Head 1,565.91 1,561.23 1,561.66 0.43 NA GW RB4 RB4 Pit with no Obs Well 1,561.32 - - - NA GW RB5 RB5 Pit at Well Head 1,563.70 1,559.06 1,559.01 -0.05 NA GW LB1 LB1 Pit with no Obs Well 1,565.21 - - - 3 GM LB2 LB8 Pit with no Obs Well 1,567.56 - - - 7 SM, GW, SM-SC LB3 LB9 Pit with no Obs Well 1,567.74 - - - 10 GM, SM-SC LB4 LB7 Pit at Well Head 1,571.64 1,560.16 1,559.01 -1.15 NA GM, SM, SC LB5 LB2 Pit at Well Head 1,563.69 1,557.26 1,558.34 1.08 NA GM, GW LB6 LB4 Pit at Well Head 1,566.73 1,558.86 1,559.81 0.95 NA GW, SW LB7 LB3 Pit at Well Head 1,560.64 1,555.86 1,555.69 -0.17 NA GW LB8 LB6 Pit with no Obs Well 1,568.13 - - - NA GW, GM LB9 LB5 Pit at Well Head 1,563.02 1,555.70 1,555.52 -0.17 NA GW, SP

1575

LB4 1570 LB2 LB3 Top of proposed ELJ surface LB1 EL. 1567.5’ 1565 Pit at ground surface LB5 LB9 EL. 1562.85’ River water surface LB6 1560

Groundwater 1555 <10’ est. thickness of streambed alluvium Pit max. depth Elevation (ft, NAVD88) 1550 EL. 1550.85’ Base of proposed ELJ Est. depth to bedrock (EL. 1548.0’) EL. 1547’ from seismic survey keyed to LiDAR 1545 streambed elevation of 1558.0’.

1540 -200 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Distance (ft)

Figure 3. Simplified geologic profile showing relationships of surface and subsurface conditions on the left bank of the river adjacent to the proposed ELJ site at Lorenz Gulch, Trinity River. Inferred bedrock profile line shown as solid black where constrained from test pit exposures; where bedrock was not encountered the maximum pit depths are connected by a solid grey line for visualization purposes. Distance along profile was set at test pit LB1 as the start point. Pits LB7 and LB8 were not shown to simplify the figure. 1600 A A’

1590

Existing ground surface Bedrock exposure 1580 Proposed ELJ location 1570 ? Qal LB‐5 (cobbles, gravels & sand) Pit max. depth 1560 ? Dms ? EL. 1550.85’ (highly deformed, <10’ Est. depth to bedrock 1550 fractured & foliated ? (EL. 1448.0’) from Elevation (ft, NAVD88) (ft, Elevation micaceous schist) seismic survey keyed 1540 to LiDAR streambed elevation of 1558.0’

1530 0 100 200 300 400 500 600 700 800 900 1000 Distance (ft)

Figure 4. Simplified geologic cross‐section at the proposed ELJ site, Lorenz Gulch, Trinity River RM 89.68. Bedrock profile is solid black where constrained from surface exposures and solid grey from seismic surveys; dashed where inferred and queried where uncertain. Refer to figure 2 for cross‐section location shown as line A to A’.

CONCLUSIONS and RECOMMENDATIONS NORCAL’s (2010) seismic survey provided critical information needed to design the foundation of the proposed ELJ. The seismic survey complemented preliminary findings of FGS (2010) that estimated shallow bedrock would limit the foundation depth for the ELJ to less than 12 feet below the streambed (EL. 1546 feet). According to the Lorenz Gulch ELJ design report (Cardno ENTRIX 2010) the ELJ foundation depth was set to 1547 + 3 feet, which conforms to the limits set out by the site investigations.

Geotechnical investigations that need to determine depth to bedrock in the TRRP project area should consider that depths will likely exceed 12 feet and groundwater may be encountered. In these cases a larger excavator in combination with a high volume pump to deplete groundwater (to improve pit wall stability) will be needed or alternatives such as drilling, push core or geophysical methods should be considered. A preliminary evaluation of LiDAR derived longitudinal profiles (see figure 5 for an example) and review of existing geologic information should be conducted in advance of field investigations. This information can aid in anticipating bedrock depths and the determination of a cost effective exploration approach.

In cases where field conditions can not be well constrained total station based surveys should be used to increase the level of certainty of how topography, hydrostratigraphic conditions and design features are related; rather than relying on LiDAR derived profiles. For example, Figure 4 shows a gap between the top elevation of LB5 and the LiDAR derived ground surface elevation at the same location. The elevation difference between these two points appears to be 1.2 feet; which exceeds some design tolerances.

Finally, the TRRP and its contractors will need flexibility to adapt plans, material supplies and costs to meet uncertainties related to fitting the proposed design to match estimated field conditions. If the bedrock depth is deeper than estimated at least one to two additional layers of wood and earth materials will be needed to construct the ELJ. A deeper excavation at the ELJ site will also affect dewatering plans and equipment sizing. Sand units identified at the base of several test pits on the left bank have a lower shear stress threshold than larger materials. If these units are laterally contiguous additional measures may be needed while constructing the features on river left, such as the use of additional wood and rock materials.

1600 1595

1590 1585 Bragdon Formation – see figure caption for interpretation. 1580 1575 1570 Lorenz Gulch ESL

1565 Proposed ELJ location 1560 Abrams Mica Schist – see figure caption for interpretation. 1555

Elevation (ft, NAVD88) ? 1550 Trust Fault Zone 1545 ?

1540 1535 ? ? 92.3 91.8 91.3 90.8 90.3 89.8 89.3 88.8 River Mile

Figure 5. LiDAR derived longitudinal profile with simplified geologic interpretation for the Trinity River from Douglas City through the Lorenz Gulch ESL. Note that residual pool depths change over the length of the longitudinal profile and may indicate variations in the thickness of in‐stream alluvium and depth to bedrock. The change in the longitudinal profile at about RM 90.8 corresponds to the fault zone of Irwin (2009) between the Bragdon Formation and Abrams Mica Schist in this location. Dip angle of the fault zone is not known and inferred for interpretive purposes. Bragdon Formation rocks are sedimentary and typically would be softer, less resistant and prone to form deeper scour holes compared to a metamorphic rock like the Abrams Mica Schist and possibly the fault zone rocks. The fault zone between these two rock units may be harder and more resistant due to changes in rock material properties and uplift associated with fault induced transformations. However, Abrams Mica Schist is older and has been subjected to a greater amount of deformation which may have decreased its resistance to fluvial erosion. To indentify whether a relation between geologic units and morphologic character exists would require an evaluation of the river longitudinal profile over several unit types and over a greater distance.

REFERENCES Cardno ENTRIX, 2011. Trinity River Engineered Log Jam Design Report, Lorenz Gulch. Prepared January 2011 for the Trinity River Restoration Program, 1313 South Main Street , Weaverville, CA 96093. 150 p.

Irwin, W.P., 2009. Geologic map of the Weaverville 15' quadrangle, Trinity County, California: U.S. Geological Survey Scientific Investigations Map 3095, scale 1:50,000. Available November 15, 2010 at: http://pubs.usgs.gov/sim/3095/.

Fiori GeoSciences, 2010. Preliminary Findings from the Lorenz Gulch Geotechnical Investigation with Regards to ELJ Design. Technical communication with TRRP Design Team. Sent November 15, 2010.

NORCAL Geophysical Consultants, Inc., 2011. Seismic Refraction Survey. Trinity River – Lorenz Gulch Site. Prepared January 6, 2011 for Erik Ammon Inc., 19905 Hirsch Court, Anderson CA 96007. NORCAL Job Number 10‐1007.01. 7 pages and 2 plates.

Woolpert, Inc., 2010. Trinity River Bathymetry, Airborne Laser Data, and Photogrammetric DTM Merging, Verification and Certification. US Bureau of Reclamation, Washington D.C.

APPENDIX A – GEOTECHNICAL TEST PIT LOGS

LOG OF TEST PIT Pit Number:LB-1 Map ID: LB-1 Sheet: 1 of 1

Project: TRRP Date Start: 08-09-2010 @ 1000 Total Depth (ft): ~5' Location: Lorenz Gulch Date End: 08-10-2010 @ 1015 Dimensions (ft): 5W x 5L x 5D N 2127585.121 Coordinates: E 6293363.515 Surface Elev: 1565.205 ft. Depth to Groundwater (ft@date/time) Logger: Rocco Fiori Datum:NAVD88 Initial: Dry Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: Dry Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details GMscb Silty sand with cobbles and boulders. Irregular contact with 1 (0 - 1') 1 underlying unit.

2 GMscb 2 Pebbly sand with cobbles. Irregular contact with underlying unit. (1 - 3') NA 3

4 Weathered Highly foliated platy schist bedrock. The upper 2 feet of rock unit 2 Bedrock was easily dug with the excavator. 5 Max pit No observation well installed

Comments: Description is of the west wall. Bedrock encountered close to ground surface along a topographic bench that conforms to strath terrace exposed on left bank of river. Backfilled with original native material excavated from pit. LOG OF TEST PIT Pit Number LB-2 Map ID: LB-5 Sheet: 1 of 1

Project: TRRP Date Start: 08-09-2010 @ 1000 Total Depth (ft): ~12' Location: Lorenz Gulch Date End: 08-09-2010 @ 1125 Dimensions (ft): 15W x 18L x 12D N 2128451.549 Coordinates: E 6293600.95 Surface Elev: 1562.851 ft. Depth to Groundwater (ft @ time) Logger: Rocco Fiori Datum:NAVD88 Initial: 7' @ 1030 Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: 6.5' @ 1045 Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 Disturbed silty sand with cobbles (3" - 5") and a few small boulders ( 5" - GMscb 2.4 12"). Contact is wavy and nearly horizontal. Particles are grain supported (0 - 2.4') 2 and well graded.

4 GWgc Moderately imbricated, well graded, grain supported gravels (<3") with 4.1 5 (2.4' - 6.5') cobble and sandy matrix.

6 Groundwater Level @ 6.5' bgs 7

Moderately imbricated, well graded, grain supported gravels (<3") with 9 GWgcb cobble and sandy matrix. Particle size increases with depth. Largest clast ~ 5.5 ( 6.5' - 12') 15" x 15" and subrounded. Note: photograph taken before static 10 groundwater level was reached. well screen lower 5' 5' lower screen well 11

12 Max pit depth

Comments: Description and photograph is of the worth wall. Pit was located 40' upstream of XS-300 on left bank approx. 50' inboard of left edge of water. Finished backfill with native material and installed Peizometer on 08-10-2010 @ 0910. LOG OF TEST PIT Pit Number LB-3 Map ID: LB-7 Sheet: 1 of 1

Project: TRRP Date Start: 08-09-2010 @ 1000 Total Depth (ft): ~10' Location: Lorenz Gulch Date End: 08-09-2010 @ 1213 Dimensions (ft): 15W x 15L x 10D N 2129027.15 Coordinates: E 6293310.026 Surface Elev: 1559.416 ft. Depth to Groundwater (ft@date/time) Logger: Rocco Fiori Datum:NAVD88 Initial: 3.6' @ 1145 Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: 4.6' @ 1205 Stratigraphic Photograph Description Unit Classification (ft) Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 GWgc Moderately imbricated, well graded gravels and cobbles with sand. Contact 2.7 (0 - 2.7') with underlying unit wavy and nearly horizontal. 2

4 Static groundwater Level 5

6 GWcg Imbricated, well graded cobbles and gravels with sand. Note: 7.3 (2.7'-10') photograph taken before static groundwater level was reached. 7

9 well screen lower 5' 5' lower screen well

10 Max pit depth

Comments: Description and photograph is of the west wall. Pit located in scour channel next to tailings pile. This location is ~8.0' lower than adjacent topography to the east. Backfilled with original native material excavated from pit. LOG OF TEST PIT Pit NumberLB-4 Map ID: LB-6 Sheet: 1 of 1

Project: TRRP Date Start: 08-09-2010 @ 1220 Total Depth (ft): ~14' Location: Lorenz Gulch Date End: 08-09-2010 @ 1240 Dimensions (ft): 15W x 20L x 14D N 2129024.741 Coordinates: E 6293583.202 Surface Elev: 1565.696 ft. Depth to Groundwater (ft@date/time) Logger: Rocco Fiori Datum:NAVD88 Initial: 12' @ 1255 Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

3 GWgc - Moderately imbricated, well graded gravels and cobbles with sand. GWgcb - Moderately imbricated, well graded cobbles and gravels with sand. 4 Contact with underlying unit wavy and nearly horizontal. 8.0 GWgc Contacts sloping and GWgcb pinches out in the upstream direction. Fining 5 upward trend of entire log suggests channel filling event; with a cause undetermined. 6

7 GWgcb 8

9 GWcb 2.0 GWcb - Moderately imbricated, poorly sorted cobbles and gravels 10 with sand. Contact with underlying unit wavy and nearly horizontal. >4.0 11 SWg Groundwater Level Well graded sands with gravel. Note: photograph taken before 12 @ 12' bgs static groundwater level was reached.

13 5' lower screen well

14 Max pit depth

Comments: Decription and photograph is of the east wall. Pit located near left bank of river in slight depression compared to adjacent surface to west. Backfilled with original native material excavated from pit. LOG OF TEST PIT Pit Number LB-5 Map ID: LB-9 Sheet: 1 of 1

Project: TRRP Date Start: 08-09-2010 @ 1245 Total Depth (ft): ~10' Location: Lorenz Gulch Date End: 08-09-2010 @ 1440 Dimensions (ft): 15W x 18L x 10D N 2129306.204 Coordinates: E 6293149.707 Surface Elev: 1562.235 ft. Depth to Groundwater (ft @ time) Logger: Rocco Fiori Datum:NAVD88 Initial: 7' @ 1345 Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 GWgs 2.0 Well imbricated, horizontally stratified gravels with sand. (0 - 2') 2 GWg 1.0 Imbricated, horizontally stratified gravels with sand. 3 (2' - 3')

4 GWcgs 2 (3'-5') Moderately imbricated and horizontally stratified cobbles with gravel 5 and sand.

6 Groundwater Level 7 @ 7' bgs SP Poorly graded sand with occasional pebble stringers. Abrupt contact 5.0 8 ( 5' - 10') with overlying unit. Spring at contact on northwest wall at 5.5' bgs. Note: photograph taken before static groundwater level was 9 hd

Max pit 5' lower screen well

Comments: Description and photograph is of the west wall. Pit is located near proposed pond outlet. Brandt had concerns the sand unit may have Mercury due to stratigraphic appearance (not color) and collected sample. Backfilled with original native material excavated from pit. Groundwater Level is about 1.0' lower in LB-5 compared to River water elevation. Water levels measured by DJB on 08-10-2010 @ 1200. LOG OF TEST PIT Pit Number LB-6 Map ID: LB-9 Sheet: 1 of 1

Project: TRRP Date Start: 08-09-2010 @ 1445 Total Depth (ft): ~12.5' Location: Lorenz Gulch Date End: 08-09-2010 @ 1530 Dimensions (ft): 10W x 15L x 12.5D N 2129125.27 Coordinates: E 6293407.08 Surface Elev: 1568.126 ft. Depth to Groundwater (ft @ time) Logger: Rocco Fiori Datum:NAVD88 Initial: 12' @ 1510 Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 GWgcs 3.0 Moderately imbricated, well graded gravels with cobbles and sand. 2 (0 - 3')

4 GWcgs Moderately imbricated, and fining upwards and well graded cobbles 3.0 5 (3' - 6') with gravels and sand.

7 GWgs 3.0 Moderately imbricated, well graded gravels with sand. 8 (6'-9') No observation well installed well observation No

9 Moderately imbricated, well graded cobbles with gravels and sand. 10 This unit has more sand than the overlying unit. GMcgs 11 (9' - 12') Groundwater Level 12 @ 12' bgs Max pit 13

Comments: Description and photograrph is of the west wall. Pit is located 35' S15E of YLM Benchmark #7. Backfilled with original native material excavated from pit. LOG OF TEST PIT Pit Number LB-7 Map ID: LB-4 Sheet: 1 of 1

Project: TRRP Date Start: 08-10-2010 @ 0915 Total Depth (ft): ~15' Location: Lorenz Gulch Date End: 08-10-2010 @ 1100 Dimensions (ft): 15W x 20L x 15D N 2128035.655 Coordinates: E 6293409.733 Surface Elev: 1570.558 ft. Depth to Groundwater (ft @ time) Logger: Rocco Fiori Datum:NAVD88 Initial: spring @ 14.5' Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 GWsgc Non-imbricated coarsening upward sandy gravels with cobbles. 2.0 (0 - 2') Abrupt contact with underlying unit. 2

3 SM Horizontally stratified silty sand with three distinct subunits. Roots 3.0 4 (2' - 5') follow contact with underlying unit.

GWscg Weakly imbricated, horizontally stratified sandy cobble with gravel. 7 3.5 (5' - 8.5') Unit pinches to less than 1' on west wall.

8 NA

10 SM Micaceous, horizontally stratified silty sand with small pebbles. Unit 3.8 11 (8.5' - 12.25') is comprised of several light and dark subunits.

14 SC Micaceous, clayey sand with sandy clay sub-units. Spring 0.25' below 2.8

(12.25' - 15') 5' lower screen well overlying contact.

15 Max pit

Comments: Description is of the east wall. Backfilled with original native material excavated from pit. LOG OF TEST PIT Pit Number LB-8 Map ID: LB-4 Sheet: 1 of 1

Project: TRRP Date Start: 08-10-2010 @ 1110 Total Depth (ft): ~9' Location: Lorenz Gulch Date End: 08-10-2010 @ 1300 Dimensions (ft): 5W x 50L x 9' to 1' D N 2127675.85 Coordinates: E 6293360.913 Surface Elev: 1567.561ft. Depth to Groundwater (ft @ time) Logger: Rocco Fiori Datum:NAVD88 Initial: Dry Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 SM 2.0 Horizontally bedded silty sand. (0 - 2') 2

3 GW Clast supported, coarsening upward clean gravel with cobbles and 2.5 (2' - 4.5') boulders. 4

NA 5

6 SM-SC Massive, silty sand with a minor amount of clay. Unit pinches out 3.5

(4.5' - 7') installed well observation No toward river bank. 7

8 Weathered Highly foliated platy schist bedrock. The upper 2 feet of rock unit Bedrock 2.5 was easily dug with the excavator. 9 Max pit

11 Simplified sketch map of trench south wall. Not to scale.

12 50'

13 SM GP 9' SM River ? Bedrock 14 ?

Comments: Pit was dug as 50' long trench perpendicular to river bank. The shallow end of the trench was approximately 50' inboard from the left streambank. At the trench end closest to the river bedrock has an apparent dip toward the river an elevated section and then dips away from the river at about 125' inboard from the rivers edge. Trench was backfilled with original native material excavated from pit. LOG OF TEST PIT Pit Number LB-9 Map ID: LB-4 Sheet: 1 of 1

Project: TRRP Date Start: 08-10-2010 @ 1305 Total Depth (ft): ~10.5' Location: Lorenz Gulch Date End: 08-10-2010 @ 1400 Dimensions (ft): 5W x 30L x 10.5' to 1' D N 2127833.184 Coordinates: E 6293392.495 Surface Elev: 1567.741 ft. Depth to Groundwater (ft @ time) Logger: Rocco Fiori Datum:NAVD88 Initial: Dry Operator: Dwayne Proctor Ex Method: 321 Cat Excavator Static: See comment below Stratigraphic Description Unit Classification (ft) Photograph Structure and Composition Group

Depth below surface Symbol Thickness (ft) Obs Well Details

1 GM 3.0 Large cobble in a silty sand matrix. 2 (0 - 3')

4 Transitional groundwater 5 level ~5' bgs

6 Micaceous, horizontally stratified silty sand with small pebbles. Unit SM - SC 7 7.5 is comprised of several light and dark subunits that may be clayey (3' - 10.5') sand or sandy clays (SC type subunits). 8

10 Max pit depth 11 Weathered Highly foliated platy schist bedrock. The upper 2 feet of rock unit 2.0 Bedrock was easily dug with the excavator. 12 No observation well installed

Simplified sketch map of trench north wall. Not to scale. 13

14 GM ? 10.5' SM 15 Bedrock ?

Comments: Description is of the north wall. Photograph is an oblique view of north wall toward to northeast. Pit was dug as 30' long trench perpendicular to river bank. The deeper end of the trench was approximately 115' inboard from the left streambank. The SM unit pinches out away from the river bank. Groundwater entered at east end (end closest to river) and filled to about 5 feet below ground surface. Trench walls were very unstable and was backfilled with original native material excavated.

APPENDIX B – NORCAL GEOPHYSICAL CONSULTANTS REPORT

LINE 1 S N 1570 1570

LINE 2 LINE 3 1560 RIVER BOTTOM 1560

1550 1550

ELEVATION (FT) 1540 1540 UPSTREAM DOWNSTREAM

1530 1530 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 DISTANCE (FT)

LINE 2 SW NE 1570 1570 LEFT RIGHT BANK LINE 1 LINE 3 BANK 1560 RIVER BOTTOM 1560 16000

15000 1550 1550 14000

13000

ELEVATION (FT) 1540 1540

UPSTREAM DOWNSTREAM VELOCITY (FT/SEC) 12000

1530 1530 11000 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

DISTANCE (FT) 10000

9000 NW LINE 3 SE 1570 1570 8000 LEFT RIGHT BANK LINE 1 LINE 2 BANK 7000 1560 RIVER BOTTOM 1560 6000

1550 1550 5000

4000

ELEVATION (FT) 1540 1540 DOWNSTREAM UPSTREAM

1530 1530 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 DISTANCE (FT) LINES 1 - 3 SESMIC REFRACTION SURVEY SCALE TRINITY RIVER - LORENZ GULCH LOCATION: DOUGLAS CITY, CALIFORNIA 0 10 20 40 (1 inch = 20 feet) CLIENT: ERIK AMMON, INC. PLATE JOB #: 10-1007.01 NORCAL GEOPHYSICAL CONSULTANTS INC.

DATE: JAN. 2011 DRAWN BY: G.RANDALL APPROVED BY: WEB