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GEOTECHNICAL DESIGN REPORT Gold Village Drought Resiliency Project

Water Storage Tank Yuba County, California

Prepared by:

BLACKBURN CONSULTING 11521 Blocker Drive, Suite 110

Auburn, CA 95603 (530) 887-1494

February 9, 2017

Prepared for:

Peterson Brustad, Inc. 1180 Iron Point Rd, Suite 260

Folsom, CA DRAFT

File No. 3023.x February 9, 2017 Mr. Jacob Rowe Peterson Brustad Inc. 1180 Iron Point Rd, Suite 260 Folsom, CA 95630 Subject: GEOTECHNICAL DESIGN REPORT Gold Village Drought Resiliency Project Water Storage Tank Yuba County, California Dear Mr. Rowe: Blackburn Consulting (BCI) is pleased to submit this Geotechnical Design Report for the Gold Village Drought Resiliency Project, Water Storage Tank located in Yuba County, California. BCI prepared this report in accordance with our proposal dated April 21, 2016. This report presents geotechnical data and provides recommendations to design and construct the proposed water tank. Please call us if you have questions or require additional information. Sincerely, BLACKBURN CONSULTING Patrick Fischer, P.E., C.E.G. Tom Blackburn, P.E., G.E. Engineering Geologist, Principal Geotechnical Engineer, Sr. Principal

Auburn Office: 11521 Blocker Drive, Suite 110 Auburn, CA 95603 (530) 887-1494 Fax (530) 887-1495

Fresno Office: (559) 438-8411 West Sacramento Office: (916) 375-8706

Geotechnical Geo-Environmental ▪ Construction Services Forensics

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GEOTECHNICAL DESIGN REPORT Gold Village Drought Resiliency Project, Water Storage Tank File No.3023.x Yuba County, California February 9, 2017

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TABLE OF CONTENTS 1 INTRODUCTION ............................................................................................. 2

1.1 Purpose ............................................................................................................................ 2 1.2 Scope of Services ............................................................................................................ 2

2 SITE LOCATION AND PROJECT DESCRIPTION .................................. 2 2.1 Site Location ................................................................................................................... 2 2.2 Project Description.......................................................................................................... 4

3 GENERAL GEOLOGIC CONDITIONS ....................................................... 5 4 SITE CONDITIONS ......................................................................................... 5 5 SUBSURFACE CONDITIONS ....................................................................... 6

5.1 Subsurface Exploration ................................................................................................... 6 5.2 Subsurface Soil Conditions ............................................................................................. 6 5.2.1 Proposed Tank Site .......................................................................................................6 5.2.2 Alternate Tank Site .......................................................................................................7

5.3 Groundwater ................................................................................................................... 7 6 LABORATORY TESTS ................................................................................... 7 7 CONCLUSIONS AND RECOMMENDATIONS .......................................... 8

7.1 General Site Suitability ................................................................................................... 8 7.2 Tank Pad Grading ........................................................................................................... 8 7.2.1 Excavatability ...............................................................................................................8 7.2.2 Site Clearing and Original Ground Preparation ...........................................................8 7.2.3 Proposed Tank Pad Overexcavation .............................................................................8 7.2.4 General Fill Placement and Compaction ......................................................................9 7.2.5 Alternate Tank Pad Grading .......................................................................................10

7.3 Excavation Sloping and Shoring ................................................................................... 10 7.4 Foundations (Both Tank Sites) ..................................................................................... 11 7.4.1 Foundation Design .....................................................................................................11 7.4.2 Lateral Resistance .......................................................................................................11 7.4.3 Settlement ...................................................................................................................12

7.5 Seismic Design Criteria (Both Tank Sites) ................................................................... 12 7.6 Soil Corrosivity ............................................................................................................. 12 7.7 Construction Issues ....................................................................................................... 13

8 RISK MANAGEMENT ..................................................................................13 9 LIMITATIONS ...............................................................................................14

FIGURES: Figure 1: Vicinity Map Figure 2: Site Plan Figure 3: Geologic Map APPENDIX A: Field Exploration, Test Pit Logs (T1-T4), Legend, Photographs APPENDIX B: Laboratory Test Results APPENDIX C: Important Information About This Geotechnical Engineering Report DRAFT


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1 INTRODUCTION

1.1 Purpose Blackburn Consulting (BCI) prepared this Geotechnical Design Report for the Water Storage Tank in the Gold Village Drought Resiliency Project. This report presents geotechnical and geologic data, and provides recommendations for design and construction of the new storage tank. BCI prepared this report for Peterson Brustad Inc. (PBI) and Yuba County to use in design and construction of the proposed improvements. Do not use or rely upon this report for different locations or improvements without the written consent of BCI. 1.2 Scope of Services BCI completed the following:

1. Discussed the proposed improvements with PBI and reviewed preliminary plans 2. Performed a preliminary review of the site, marked test pit locations, notified

Underground Service Alert 3. Observed, logged, and sampled 4 test pits ranging from 3 to 4.5 feet below the ground

surface (bgs) 4. Performed laboratory tests on soil samples obtained from the test pits 5. Performed engineering analysis and calculations to develop our conclusions and

recommendations for tank design and construction 2 SITE LOCATION AND PROJECT DESCRIPTION

2.1 Site Location The project site is near the town of Smartsville, off Hammonton-Smartsville Road, in Yuba County, California. Figure 1 shows the general site location. The tank site (Proposed and Alternate) is located off South Golden Parkway approximately 1000 feet south of the intersection with Hammonton-Smartsville Road. The Proposed tank site is adjacent to the north side of an existing water storage tank, primarily within area currently used for access road/parking. BCI also evaluated an Alternate tank site (selected by PBI) adjacent to the south side of the existing tank. Photographs 1 through 3 below show the tank sites. DRAFT


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Photo 1) Existing water storage tank (looking south from access road)

Photo 2) Proposed water tank site (looking west-southwest from access road) DRAFT


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Photo 3) Alternate tank site on south side of existing tank (looking north-northwest)

2.2 Project Description The project consists of design and construction of an approximate 250,000-gallon water tank. PBI provided the following information:

• The new tank will be 55 feet in diameter and have a water height of approximately 15 feet

• The tank pad will include a perimeter access road (gravel cover) • The Proposed tank pad will be filled to grade; on the order of 1.5 to 3 feet at the center

and east side, and 5 to 6 feet at the west side • The tank foundation will consist of a concrete ring footing and interior spread footing (for

an interior roof support column) • The interior pad will be compacted rock/baserock

Figure 2 shows site details and the general location of the proposed improvements. The Alternate site, located south of the existing tank, is in unimproved area that will need to be cut down several feet to achieve a tank pad. DRAFT


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3 GENERAL GEOLOGIC CONDITIONS

Based on our work and published geologic mapping1, the site is underlain by volcanic rock (volcaniclastics, lavas, breccias, and massive flows of the Smartsville Complex) with varying degrees of metamorphism. The rock has a relatively thin soil profile and is generally decomposed to intensely weathered near the surface and becomes less weathered and fractured with depth. “Knobs” of hard rock tend to weather out and are exposed at the ground surface in undisturbed locations. Figure 3 shows the general geology of the project vicinity. The Fault Activity Map of California and Adjacent Areas2 does not identify any active or potentially active faults crossing or adjacent to the site. The site does not lie within or adjacent to an Alquist–Priolo Earthquake Fault Zone3. We do not expect ground rupture and/or fault creep to occur at the site; however, some level of ground motion will occur from seismic activity in the region. The site is underlain by rock that can contain naturally occurring asbestos minerals (NOA). However, we did not observe serpentine or other ultramafic rock (a host rock for NOA) during our site review and subsurface exploration and none is mapped in the vicinity. The California Geological Survey4 maps the project area as outside of any area considered as “Areas More Likely to Contain Naturally Occurring Asbestos.” The Yuba County General Plan (2008) indicates that the site is outside of areas mapped as “Potential Asbestos-Bearing Rocks” (Exhibit GS-5). We did not observe evidence of past mining or explorations on or adjacent to the site. 4 SITE CONDITIONS

The Proposed tank site is:

• Located adjacent to the north side of the existing tank (mostly within the security fence) • Primarily within an area leveled for access/parking and at an elevation of approximately

995 feet • Primarily gravel covered (within the fenced area) • Partly underlain by existing fill placed for leveling of the access/parking area

1 Saucedo, G.J., and Wagner, D.L., 1992, Geologic Map of the Chico Quadrangle: California Division of Mines and Geology, Regional Geologic Map No. 7A, 1:250,000 scale 2 Jennings, Charles W., 1994, Fault Activity Map of California and Adjacent Areas with Location and Ages of Recent Volcanic Eruption; California Department of Conservation, Division of Mines and Geology, Geologic Data Map No. 6

Jennings, Charles W. and Bryant, William A., 2010, Fault Activity Map of California (interactive web map); California Geological Survey, Geologic Data Map No. 6. 3 William A. Bryant and Earl W. Hart, 2007 (Interim Revision), Fault-Rupture Hazard Zones in California; California Department of Conservation, California Geological Survey, Special Publication 42. 4 Churchill, R.K., and Hill, R.L., 2000, A General Location Guide for Ultramafic Rock in California – Areas More Likely to Contain Naturally Occurring Asbestos; Open File Report 2000-19. DRAFT


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• Sloped down to the west (at the west side of the pad) into unimproved area outside the fence with a gradient of approximately 3.5:1 (horizontal to vertical)

• Covered with thin grasses and several trees within the unimproved portion The Alternate tank site is:

• Located adjacent to the south side of the existing tank in unimproved area outside of the security fence

• At an elevation that varies from approximately 997 feet to 1,001 feet • Sloped gently to the south-southwest at a gradient of approximately 5:1 (H:V) • Covered with thin grasses, trees and bushes, and has many rock outcrops (see

Photo 3 above) See Figure 2 for site details. 5 SUBSURFACE CONDITIONS

5.1 Subsurface Exploration To characterize the subsurface soil conditions, BCI observed and logged 4 test pits at the two tank sites. Figure 2 shows the test pit locations. Test pit locations are not surveyed; therefore, consider the plotted locations as approximate. Appendix A contains details of our excavation method, logs of the test pits, and test pit photographs. 5.2 Subsurface Soil Conditions 5.2.1 Proposed Tank Site

Our test pits show that the Proposed tank site has a thin cover of existing fill that appears to extend from approximately halfway through the tank pad to the west side of the tank pad. Figure 2 shows the approximate location of existing fill. The fill consists of sandy gravel (GW) with clay, cobbles, and boulders. This is underlain by 0 to 1 foot of silty sand (SM) that overlies decomposed to intensely weathered rock to maximum depth of test pits (4.5 feet). We encountered practical refusal to excavation in moderately weathered, moderately hard rock at a depth of approximately 1.5 feet into the rock. The eastern half of the tank pad appears to be cut to grade (1 to 2 feet) and rock is exposed outside of the gravel covered area. We expect weathered rock to be present immediately below the gravel cover on the east side of the tank pad.

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5.2.2 Alternate Tank Site

Our test pits show that the alternate tank site has a soil cover approximately 1 to 2 feet thick that consists of a sandy gravel/cobbles (GW) between rock outcrop locations. This is underlain by decomposed to intensely weathered rock to maximum depth of test pits (4 feet). We encountered practical refusal to excavation in moderately weathered, moderately hard rock at a depth of approximately 2 feet into the rock. 5.3 Groundwater During our subsurface exploration in January 2017, we did not observe groundwater or indications of springs or seeps on or adjacent to the tank sites. 6 LABORATORY TESTS

We completed the following laboratory tests on representative soil samples from our borings:

• Direct shear to estimate soil strength under a range of normal pressures • Compaction curve (Proctor) for compaction characteristics • Sieve analysis for material characterization • Corrosivity Tests (Sulfate – CTM 417, Chloride – CTM 422, pH and Resistivity – CTM

643) to evaluate corrosion potential of piping and below ground structures. A direct shear test on remolded soil/decomposed rock from near the surface at the tank site indicates an internal friction angle of 44 degrees and cohesion of 105 pounds per square foot (psf) at normal pressures of 500 to 2,000 psf. A compaction curve on a mixture of soil and weathered rock results in a maximum dry density of 131.9 pcf and an optimum moisture content of 7.8%. A sieve analysis on a mixture of excavated soil and weathered rock shows a clayey, medium to coarse sand with gravel. Corrosivity tests on a mixture of soil/weathered rock within 4 feet of the surface indicate a pH of 5.37, minimum resistivity of 16,350 ohm-cm, sulfates content of 9.5 parts per million (ppm), and chloride content of 8.1 ppm. See Appendix B for test results.

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7 CONCLUSIONS AND RECOMMENDATIONS

7.1 General Site Suitability The tank sites are suitable for the proposed tank when the ground surface is prepared, fill placed, and foundation designed in accordance with the recommendations we provide below. Based on our site observations and subsurface findings, potential settlement of the tank is minimal when the pad is prepared as recommend below. Due to the presence of existing fill of unknown/variable quality at the Proposed tank site, existing fill should be removed down to undisturbed, weathered rock. We provide overexcavation and recompaction recommendations below. 7.2 Tank Pad Grading 7.2.1 Excavatability

Based on the soil/rock conditions we observed at both tank sites, we estimate that soil and weathered rock will be excavatable using conventional grading equipment such as dozers, backhoes, excavators, and scrapers to depths on the order of 3 to 5 feet. Knobs of hard rock, that may require blasting and/or chiseling to remove can be encountered at and near the surface (particularly at the “Alternate” tank site). Additionally, large cobble/boulder size material will be generated by excavations which will require removal from fill material and/or special placement methods. 7.2.2 Site Clearing and Original Ground Preparation

Prior to making cuts and fills, remove trees and bushes, and strip any debris, organics and vegetation from the surface including roots greater than 2-inches in diameter. Do not use strippings within engineered fill. Strippings may be used as ground cover in non-structural fill areas or disposed off-site. 7.2.3 Proposed Tank Pad Overexcavation

Due to the presence of fill of unknown/variable quality and to provide for more uniform tank support/settlement, overexcavate and fill the Proposed tank pad as described below:

• Overexcavate fill soils within the tank footprint and 5 feet beyond the tank perimeter to the depth of weathered rock (approximately 1 to 3 feet of overexcavation on the west half of the tank pad).

• Review the base of the excavation for presence of unsuitable materials (such as additional fill and/or organic material) and increase the excavation depth as necessary to remove these materials. BCI should review the base of the excavation.

• Moisture condition the bottom of the excavation to 0%-3% above optimum moisture content. DRAFT


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• Compact the exposed subgrade to a minimum 95% relative compaction based on ASTM D1557. If not testable due to the presence of rocky material, compact with a minimum of five passes of a padded drum compactor making overlapping passes until coverage is complete. Modify the performance specification as required by the project geotechnical engineer based on equipment used, materials exposed, and observed compaction results.

• Provide a key for fill placement, and bench and place fill in accordance with the General Fill Placement and Compaction recommendations below. Fill may consist of overexcavated soils screened to remove rock over 4 inches in diameter and/or imported soils approved by BCI prior to transport to the site.

7.2.4 General Fill Placement and Compaction

General fill at the tank sites may consist of on-site soil and rock provided it contains no rocks larger than 4 inches in maximum dimension and is free of debris and concentrations of vegetation. Rocks larger than 4 inches but smaller than 24 inches in greatest dimension may be used in fill at depths greater than 4 ft below finish grade. Place rocks to prevent nesting and voids and in a manner so that soil can be adequately compacted around the rocks (filling all voids). Placement of non-testable, rocky fill material must be observed by BCI for adequate compaction effort. Do not place large rock (cobbles and boulders) in areas proposed for piping (where trenches will need to be excavated). If import fill is required, it must meet the following requirements:

• Classified as Sandy Silt (ML), Silty Sand (SM), or Silty Gravel (GM), • Contain no concentrations of organics, debris, and other deleterious materials, • Maximum particle size of 3 inches, • Maximum of 50% passing the #200 sieve, • Expansion index less than or equal to 20, per ASTM D4829,

BCI must approve imported material prior to its delivery to the site. Place and compact fill as follows:

• Scarify the subgrade to a depth of 8 inches (if rock is exposed scarification is not necessary).

• Moisture condition the scarified subgrade within 3% of optimum moisture content. • Compact the exposed subgrade soil/decomposed rock to a minimum 95% relative

compaction based on ASTM D1557. If not testable due to the presence of rocky material, compact with a minimum of five passes of a padded drum compactor making overlapping passes until coverage is complete. BCI can modify the performance specification as required based on equipment used, materials exposed, and observed compaction results.

• Place fill in maximum 8-inch thick loose lifts. • Moisture condition to within 3% of optimum. DRAFT


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• Compact to a minimum 95% relative compaction based on ASTM D1557. • Where soil is too rocky for compaction testing, place rocky fill in loose lifts no

thicker than 1 foot prior to compaction. Moisture condition the matrix soil uniformly to at least 2 percent over the optimum moisture content (visual manual method) prior to compaction. Compact each lift of rocky fill with a minimum of five passes of a Caterpillar (CAT) 825 padded drum compactor (or an equivalent) making overlapping passes until coverage is complete. Modify the performance specification as required by the project geotechnical engineer based on actual equipment used and observed compaction results.

For fills that are 5 ft or greater in height and placed on or against a slope with a gradient of 5(H):1(V) or steeper (such as at the west side of the Proposed tank pad), provide a fill key at the toe of the fill slope as follows:

• The key must be a minimum of 10 ft wide and 1 ft deep • Slope the key at a minimum gradient of 2% into the slope and extend 2 ft beyond the toe of fill • If restricted access or hard rock will not allow for a 10 ft wide toe-bench, the bench can be

reduced to a minimum width of 6 ft provided the contractor can show that compaction equipment can achieve the specified compaction for the full width of the bench.

Where fill will be placed on or against slopes with a gradient of 5(H):1(V) or steeper (such as on the west side of the planned tank pad), fill must be benched into the slope as follows:

• Bench to remove loose surficial soils and loose rock • Step benches such that they are generally 1 to 2 feet in height and depth (into the existing slope) • If benching will interfere with existing vegetation (such as trees to remain), BCI can review and

modify on a case-by-case basis 7.2.5 Alternate Tank Pad Grading

If used, the Alternate tank site is expected to be “cut down” several feet to finish grade. To obtain a uniform pad for the tank base, excavate the pad down to an elevation such that a minimum of 6-inches of rock (crushed rock or aggregate baserock) underlayment can be used. This may require chiseling of rock “knobs” to obtain final subgrade elevation. Place fill in accordance with our grading recommendations above. 7.3 Excavation Sloping and Shoring The contractor is responsible for the safety of all temporary excavations and must provide excavation sloping and shoring in accordance with current Cal OSHA requirements. The contractor must determine the proper construction technique for excavation, trench safety, and backfill operations. DRAFT


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With the exception of existing fill areas and areas where fill will be placed, the tank sites are underlain by weathered, fractured rock with a thin soil cover. For project planning and design, anticipate temporary sloping and shoring for “Stable Rock” (Federal Register, 29 CFR, Part 1926, Subpart P; Occupational Safety and Health Standards – Excavations), which allows for a vertical trench slope; however, modifications to sloping may be necessary due to loose surficial soils and/or potential for falling rock. Breakout of large rock pieces can result in widening and/or over-steepening of excavations. Where fill is or will be present, anticipate temporary sloping and shoring for “Type B” soil which requires a 1:1 trench slope. The contractor will need to evaluate the impact of construction vibrations, actual soil/rock conditions exposed in excavations, and other factors that may promote excavation wall instability at the time of construction and adjust sloping/shoring accordingly. Surcharge loads such as trench spoils, equipment, etc. should not be placed adjacent to an open excavation (within a distance of ½ the height of the excavation). The preceding information is guideline information only. 7.4 Foundations (Both Tank Sites) 7.4.1 Foundation Design

The tank foundation will consist of a perimeter (ring) footing, with a compacted, crushed rock/baserock interior. Design foundations in accordance with the following:

• Embed a minimum of 18 inches below the prepared subgrade. • Use a minimum width of 18 inches. • Size footings so they do not exceed an allowable bearing capacity of 3,500 pounds per

square foot (psf). The allowable bearing capacity includes a safety factor of 3. • The allowable bearing capacity can be increased by one-third if seismic and/or wind

loads are included. Clean all footing excavations of debris and loose soil prior to placing concrete, and slope all finished surfaces away from the tank perimeter to avoid ponding of water at or near foundations. 7.4.2 Lateral Resistance

Lateral forces will be resisted by passive resistance of the soil adjacent to the foundations and/or friction developed between the base of the footing and the underlying soil. To resist lateral movement, use:

• Coefficient of friction of 0.35. • Passive earth pressure of 250 psf per foot of embedment depth (up to a maximum of

2,500 psf). Decrease the passive pressure by one-half if both friction and passive pressure are used.

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7.4.3 Settlement

Minor tank settlement will likely occur when the tank is initially filled (particularly at the west side of the planned tank location where deeper fill will be present). Based on a water height of approximately 15 feet and the anticipated soil and rock conditions, we estimate total and differential (from center to edge) settlement will be less than ½ inch at either tank site. 7.5 Seismic Design Criteria (Both Tank Sites) Based on the soil profile and in accordance with AWWA D103-9, Table 3 (and the California Building Code, 2016), we classify the tank sites as Site Class B. Site Class is based on the mapped geologic conditions, observed site conditions, and our subsurface exploration. We provide a summary of applicable seismic design parameters (per AWWA D103-9, General Procedure) for the site in the table below.

SEISMIC DESIGN PARAMETERS FOR SITE CLASS B GOLD VILLAGE DROUGHT RESILIENCY PROJECT WATER TANK SITE

SS – Acceleration Parameter 0.530 g

S1 – Acceleration Parameter 0.248 g

Fa – Site Coefficient 1.0

Fv – Site Coefficient 1.0

SMS – Adjusted MCE* Spectral Response Acceleration Parameter 0.530 g

SM1 – Adjusted MCE* Spectral Response Acceleration Parameter 0.248 g

SDS – Design Spectral Acceleration Parameter 0.353 g

SD1 – Design Spectral Acceleration Parameter 0.165 g

TL – Long Period Transition Period 12 secs * Maximum Considered Earthquake

7.6 Soil Corrosivity A sample of soil/weathered rock from the tank area was tested for corrosion characteristics (pH, resistivity, chlorides, and sulfates). See Appendix B for the laboratory test results. Based on the test results, the site soil has a relatively low pH (5.37), moderate resistivity (16,350 ohm-cm), and low chloride and sulfate content (<10 ppm). In general, our laboratory test results and the soil/rock conditions suggest a low corrosion potential for steel. The low pH suggests the soil/rock conditions can be deleterious to concrete. PBI should consider the need for corrosion protection based on the type of materials used and soil/rock conditions indicated.

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7.7 Construction Issues We don’t anticipate significant geotechnical related construction issues during tank pad preparation or foundation construction. Potential construction issues at both tank sites include:

• If construction proceeds during the winter/spring months and shortly following (wet season), wet soil conditions can create difficulty in obtaining proper soil moisture conditions for site work, backfill, and compaction.

• Hard rock can be encountered that will require chiseling and/or blasting to facilitate removal.

• Large rock pieces will be generated during excavation that will need to be removed from the site, broken down for use in fill, and/or require special placement methods.

• Irregular subgrade surfaces (due to presence of hard rock) can create difficulty in placement and compaction of fill.

• We do not expect groundwater to be encountered for shallow excavation and/or pipeline installations; however, during the wet season, shallow, perched groundwater can accumulate. If accumulations of perched groundwater occur, sump pumps should be adequate to dewater.

8 RISK MANAGEMENT

Our experience and that of our profession clearly indicates that the risks of costly design, construction, and maintenance problems can be significantly lowered by retaining the geotechnical engineer of record to provide additional services during design and construction. For this project, retain BCI to:

• Review and provide comments on the civil plans and specifications prior to construction. • Monitor construction to check and document our report assumptions. At a minimum,

BCI should observe and test overexcavation/re-compaction, site grading, backfill, and foundation excavation.

• Update this report if design changes occur, 2 years or more lapses between this report and construction, and/or site conditions have changed.

If we are not retained to perform the above applicable services, mistakes may occur that increase construction and maintenance costs. BCI is not responsible for any other party’s interpretation of our report, and subsequent addendums, letters, and discussions. See Appendix C for important information about this report.

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9 LIMITATIONS

BCI performed services in accordance with generally accepted geotechnical engineering principles and practices currently used in this area. Where referenced, we used ASTM Test Method standards as a general (not strict) guideline only. We do not warranty our services. BCI based this report on the current site conditions. We assume the soil and groundwater conditions encountered in our explorations are representative of the subsurface conditions throughout the project. Conditions at locations other than our explorations could be different. See Appendix A for our Test Pit logs. The lines designating the interface between soil types are approximate. The transition between material types may be abrupt or gradual. We base our recommendations on the final logs, which represent our interpretation of the field logs, laboratory tests, and general knowledge of the site and geological conditions. The groundwater elevations discussed in this report represent the groundwater elevation during the time of our subsurface exploration and at the exploration locations, or as otherwise referenced. Groundwater may be at lower or higher elevations in the future. Modern design and construction are complex, with many regulatory sources/restrictions, involved parties, construction alternatives, etc. It is common to experience changes and delays. The owner should set aside a reasonable contingency fund based on complexities and cost estimates to cover changes and delays.

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Geotechnical Geo-Environmental Construction Services Forensics

FIGURES

Figure 1: Vicinity Map Figure 2: Site Plan

Figure 3: Geologic Map

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© 2017 HERE © AND © 2017 Microsoft Corporation

11521 Blocker Drive, Suite 110

Auburn, CA 95603

Phone: (530) 887-1494

Fax: (530) 887-1495

www.blackburnconsulting.com

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Site Grading Plan, Sheet C1, dated November 2016.

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GEOLOGIC MAP

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Auriferous Gravels

Jurassic volcanic rocks(Pyroclastic rocks and flows)

Volcanic rocks

Quartz diorite and tonalite

Gabbroic rocks

Massive diabase

L E G E N D

Approx. Fault Location

Stike and dip of bedsGeneral strike and dip of stratified rocks

Stike and dip of overturned beds

Vertical beds

Stike and dip of foliationGeneral strike and dip of foliation in metamorphic rocks

Vertical foliation

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APPENDIX A

Field Exploration, Test Pit Logs (T1-T4), Legend, Photographs

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FIELD EXPLORATION BCI excavated and sampled four exploratory test pits on January 16, 2017. Test Pit depths range from 3.0 to 4.5 feet below the ground surface. Test Pit depth was limited by hard rock excavation. BCI planned the general location of the Test Pits based on the proposed improvements, preliminary plans provided by PBI, site access, and observed site conditions (such as exposed rock and apparent fill locations). We show the approximate Test Pit locations on the Site Plan (Figure 2) and provide detailed information on the logs. Our excavation contractor (CME) excavated the Test Pits with a Case 580 rubber-tired backhoe equipped with an 18-inch wide bucket. A BCI geologist logged the Test Pits and retrieved soil/rock samples. We retrieved bulk soil samples from excavation cuttings and placed this material in large cloth bags. During excavation, we performed field strength testing with a pocket penetrometer on select cohesive and/or cemented soil/rock samples. We note the field tests on the logs.

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4.5+

Sandy Gravel (GW) 3 to 4 inches of gravel (AB) ground cover.

FILL, Sandy Gravel (GW) with clay and cobbles/boulders, (mediumdense), brown, moist; approx. 50% cobbles and boulders to 3"-14"diameter.

Metavolcanic Rock, light brown and yellow-brown, intensely tomoderately weathered, moderately soft to hard, intensely fractured.Breaks out in pieces 6"-14" in diameter.

Total Depth - 4 ftNear refusal to excavation

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ND

PE

N. (

tsf)

1LO

GP

ER

PA

GE

GO

LD V

ILLA

GE

TE

ST

PIT

S.G

PJ

BLA

CK

BR

N.G

DT

2/8

/17

DRAFT

1.0

4.5+

Sandy Gravel (GW) approximately 6 inches of gravel (AB) groundcover.

FILL, Sandy Gravel (GW) with clay and cobbles, (medium dense),brown, moist. 6 inches of gravel (AB) ground cover, approx. ~ 40%cobbles 6" diameter. Fill thickens in downslope direction (towardfenceline).

Silty Sand (SM) with clay, loose, dark brown, moist, some roots.

Metavolcanic Rock, light brown and yellow-brown, decomposed tointensely weathered, and grades down to moderately weathered,moderately soft to moderately hard, intensely fractured. Excavatesout in blocky pieces up to 14" in diameter.

Total Depth - 4.5 ftNear refusal to excavation

PA, DS,CP

5

Time of Reading:

LOG OF TEST PIT T2

Equipment:

Date Excavated:D

EP

TH

(fee

t)

MO

IST

UR

E(%

)

GR

AP

HIC

LO

G

1/16/17


PFFLogged by:


994.0


NA




3023.x

DR

Y U

NIT

WT

. (pc

f)

SA

MPL

E

LA

BT

ES

TS

HA

ND

PE

N. (

tsf)

1LO

GP

ER

PA

GE

GO

LD V

ILLA

GE

TE

ST

PIT

S.G

PJ

BLA

CK

BR

N.G

DT

2/8

/17

DRAFT

4.5+

Sandy Gravel/Cobbles (GW) with boulders, (loose to medium dense),brown, moist, some roots. Residual soil with boulders up to 18"diameter.

Metavolcanic Rock, light brown and yellow-brown, decomposed tointensely weathered and grades down to moderately weathered,moderately soft to moderately hard, intensely fractured. Excavatesout in blocky pieces up to 14" in diameter, some large, hard rockpieces.

Total Depth - 4 ftNear refusal to excavation

5

Time of Reading:

LOG OF TEST PIT T3

Equipment:

Date Excavated:D

EP

TH

(fee

t)

MO

IST

UR

E(%

)

GR

AP

HIC

LO

G

1/16/17


PFFLogged by:


1000.0


NA




3023.x

DR

Y U

NIT

WT

. (pc

f)

SA

MPL

E

LA

BT

ES

TS

HA

ND

PE

N. (

tsf)

1LO

GP

ER

PA

GE

GO

LD V

ILLA

GE

TE

ST

PIT

S.G

PJ

BLA

CK

BR

N.G

DT

2/8

/17

DRAFT

4.5+

Sandy Gravel/Cobbles (GW) with boulders, (loose to medium dense),brown, moist, some roots. Residual soil with boulders up to 12"diameter.

Metavolcanic Rock, light brown and yellow-brown, decomposed tointensely weathered and grades down to moderately weathered,moderately soft to moderately hard, intensely fractured. Excavatesout in blocky pieces up to 3"-12" in diameter, some hard rock pieces.

Total Depth - 3 ftPractical refusal to excavation

5

Time of Reading:

LOG OF TEST PIT T4

Equipment:

Date Excavated:D

EP

TH

(fee

t)

MO

IST

UR

E(%

)

GR

AP

HIC

LO

G

1/16/17


PFFLogged by:


999.0


NA




3023.x

DR

Y U

NIT

WT

. (pc

f)

SA

MPL

E

LA

BT

ES

TS

HA

ND

PE

N. (

tsf)

1LO

GP

ER

PA

GE

GO

LD V

ILLA

GE

TE

ST

PIT

S.G

PJ

BLA

CK

BR

N.G

DT

2/8

/17

DRAFT

BORING LOG / TEST PITLEGEND AND SOIL DESCRIPTIONS

UNIFIED SOIL CLASSIFICATION (ASTM D 2487)MATERIAL

TYPESGROUP

SYMBOLCRITERIA FOR ASSIGNING SOIL GROUP NAMES SOIL GROUPNAMES

PI PLOTS BELOW "A" LINE

LL (oven dried)<0.75/LL (not dried)

FINES CLASSIFY AS ML OR MH

FINES CLASSIFY AS CL OR CH

FINES CLASSIFY AS CL OR CH

FINES CLASSIFY AS ML OR MHCOARSE-GRAINED

SOILS>50%

RETAINED ONNO. 200SIEVE

FINE-GRAINED

SOILS>50%

PASSINGNO. 200SIEVE

GRAVELS

>50% OF COARSEFRACTION RETAINED

ON NO. 4 SIEVE

SANDS

<50% OF COARSEFRACTION RETAINED

ON NO. 4 SIEVE

SILTS AND CLAYS

LIQUID LIMIT <50

SILTS AND CLAYS

LIQUID LIMIT >50

CLEANGRAVELS<5% FINESGRAVELS

WITH FINES>12% FINES

CLEANSANDS

<5% FINESSANDS

WITH FINES>12% FINES

INORGANIC

INORGANIC

ORGANIC

ORGANIC

HIGHLY ORGANIC SOILS PRIMARILY ORGANIC MATTER,DARK COLOR, ORGANIC ODOR

Cu > 4 AND 1 < Cc < 3

Cu < 4 AND/OR 1 > Cc > 3

Cu > 6 AND 1 < Cc < 3

Cu < 6 AND/OR 1 > Cc > 3

PI PLOTS ON OR ABOVE "A" LINE

LL (oven dried)<0.75/LL (not dried)

GW

GP

GM

GC

SW

SP

SM

SC

CL

ML

OL

CH

MH

OH

PT

POORLY-GRADED GRAVEL

WELL-GRADED GRAVEL

SILTY GRAVEL

CLAYEY GRAVEL

WELL-GRADED SAND

POORLY-GRADED SAND

SILTY SAND

CLAYEY SAND

LEAN CLAY

SILT

ORGANIC CLAY OR SILT

FAT CLAY

ELASTIC SILT

PEAT

ORGANIC CLAY OR SILT

Auger or backhoe cuttings

SAMPLE TYPES

ADDITIONAL TESTS- Consolidation- Compaction Curve- Corrosivity Testing- Consolidated Undrained Triaxial- Direct Shear- Expansion Index- Permeability- Partical Size Analysis- Plasticity Index- Pocket Penetrometer- R-Value- Sand Equivalent- Specific Gravity- Shrinkage Limit- Swell Potential- Pocket Torvane Shear Test- Unconfined Compression- Unconsolidated Undrained TriaxialCL-ML

PLASTICITY CHART

ML or OL

MH or OH

"A" L

INE

100

40

47

PLAS

TICI

TY IN

DEX

(PI)

LIQUID LIMIT (LL)

NOTE: Cu=D /DCc=(D ) / D xD

60 10

30 10 602

BLOW COUNTThe number of blows of a 140-lb. hammer falling30-inches required to drive the sampler the last12-inches of an 18-inch drive. The notation 50/4indicates 4-inches of penetration achieved in 50 blows.

Shelby tube

Standard Penetration (SPT)

Modified California

Rock core

GROUND WATER LEVELS

Water level at time of drilling

Later water level after drilling

"U" L

INE

20 30 40 60 70 80 90 100 11050

10

0

20

30

50

60

16

CL or OL

CH or OH

For classification of fine-grained soils andfine-grained fraction of coarse-grainedsoils.

Equation of "A"-lineHorizontal at PI=4 to LL=25.5,then PI=0.73 (LL - 20)

Equation of "U"-lineVertical at LL=16 to PI=7,then PI=0.9 (LL - 8)

CCPCRCUDS EI PPAPIPP RSESGSLSWTVUCUU

GRAPHICSYMBOL

11521 Blocker Drive, Suite 110Auburn,CA 95603Phone: (530) 887-1494Fax: (530) 887-1495www.blackburnconsulting.com

1/2/

2013

Borin

g Te

st P

it Le

gend

with

Gra

phic

s.dw

g

DRAFT

GoldVillageDroughtResilencyProject BCIProjectNo3023.X

Test Pit T1 Test Pit T1

Test Pit T1 Test Pit T2 DRAFT




DRAFT



Test Pit T3 Test Pit T3 DRAFT


APPENDIX B

Laboratory Test Results

DRAFT

DIRECT SHEAR TEST REPORTBlackburn ConsultingW. Sacramento, CA

Client: Peterson, Brustad, Inc.

Project: Gold Village Drought Resiliency Project

Source of Sample: T2 Depth: 2.5-4.0'

Sample Number: A

Proj. No.: 3023.X Date Sampled: 1/30/2017

Sample Type: Remolded

Description: CLAYEY medium to coarse SAND,

light brown

Assumed Specific Gravity= 2.7

Remarks:

Figure

Sample No.

Water Content, %Dry Density, pcfSaturation, %Void RatioDiameter, in.Height, in.Water Content, %Dry Density, pcfSaturation, %Void RatioDiameter, in.Height, in.

Normal Stress, psfFail. Stress, psf Strain, %Ult. Stress, psf Strain, %Strain rate, in./min.

Initi

alAt

Tes

t

Shea

r Stre

ss, p

sf

0

500

1000

1500

2000

2500

3000

Strain, %

0 5 10 15 20

1

2

3

Verti

cal D

efor

mat

ion,

in.

0.015

0.01

0.005

0

-0.005

-0.01

-0.015

Strain, %

0 3 6 9 12

Dilation

Consol.

12

3

Fail.

Stre

ss, p

sf

0

1000

2000

3000

Normal Stress, psf

0 1000 2000 3000

C, psf, deg Tan()

Results105.044.00.97

1

8.2

120.0

54.7

0.4049

2.362

0.945

15.4

119.1

100.0

0.4150

2.362

0.952500.0525.5

3.8

0.001

2

8.2

120.1

54.9

0.4029

2.362

0.945

15.6

118.7

100.0

0.4204

2.362

0.9571000.01163.4

1.7

0.001

3

8.2

119.7

54.3

0.4079

2.362

0.945

15.0

119.5

98.6

0.4106

2.362

0.9472000.02004.3

1.7

0.001

DRAFT

Blackburn Consulting

W. Sacramento, CA

1/30/2017

(no specification provided)

PL= LL= PI=

D90= D85= D60=D50= D30= D15=D10= Cu= Cc=

USCS= AASHTO=

*

CLAYEY medium to coarse SAND with GRAVEL, lightbrown3

21.51

.75.375#4

#10#20#40#60

#140#200

100100

9996949084746148393128

9.3343 5.1592 0.81010.4706 0.0978

Peterson, Brustad, Inc.Gold Village Drought Resiliency Project

3023.X

Material Description

Atterberg Limits

Coefficients

Classification

Remarks

Source of Sample: T2 Depth: 2.5-4.0'Sample Number: A Date:

Client:Project:

Project No: Figure

SIEVE PERCENT SPEC.* PASS?SIZE FINER PERCENT (X=NO)

PER

CEN

T FI

NER

0

10

20

30

40

50

60

70

80

90

100

GRAIN SIZE - mm.

0.0010.010.1110100

% +3" Coarse% Gravel

Fine Coarse Medium% Sand

Fine Silt% Fines

Clay0 6 10 10 26 20 28

6 in

.

3 in

.

2 in

.1½

in.

1 in

.¾

in.

½ in

.3/

8 in

.

#4 #10

#20

#30

#40

#60

#100

#140

#200

Particle Size Distribution Report

DRAFT

COMPACTION TEST REPORTD

ry d

ensi

ty, p

cf

115

120

125

130

135

140

Water content, % - Rock Corrected - Uncorrected

4 6 8 10 12 14 16

7.8%, 131.9 pcf 8.2%, 130.2 pcf

ZAV forSp.G. =2.60

Test specification:ASTM D 4718-87 Oversize Corr. Applied to Each Test Point

ASTM D 698-12 Method B Standard

2.5-4.0' 2.6 10 28

CLAYEY medium to coarse SAND withGRAVEL, light brown

3023.X Peterson, Brustad, Inc.

Elev/ Classification Nat.Sp.G. LL PI

% > % <Depth USCS AASHTO Moist. 3/8 in. No.200

ROCK CORRECTED TEST RESULTS UNCORRECTED MATERIAL DESCRIPTION

Project No. Client: Remarks:Project:

Source of Sample: T2 Sample Number: A

Blackburn Consulting

W. Sacramento, CA Figure

130.2 pcf Maximum dry density = 131.9 pcf

8.2 % Optimum moisture = 7.8 %

Gold Village Drought Resiliency Project

DRAFT

DRAFT


APPENDIX C

Important Information about This Geotechnical – Engineering Report

DRAFT

Geotechnical-Engineering ReportImportant Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as possible. In that way, clients can benefit from a lowered exposure to the subsurface problems that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed below, contact your GBA-member geotechnical engineer. Active involvement in the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project.

Geotechnical-Engineering Services Are Performed for Specific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Those who rely on a geotechnical-engineering report prepared for a different client can be seriously misled. No one except authorized client representatives should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one – not even you – should apply this report for any purpose or project except the one originally contemplated.

Read this Report in FullCostly problems have occurred because those relying on a geotechnical-engineering report did not read it in its entirety. Do not rely on an executive summary. Do not read selected elements only. Read this report in full.

You Need to Inform Your Geotechnical Engineer about ChangeYour geotechnical engineer considered unique, project-specific factors when designing the study behind this report and developing the confirmation-dependent recommendations the report conveys. A few typical factors include: • the client’s goals, objectives, budget, schedule, and risk-management preferences; • the general nature of the structure involved, its size, configuration, and performance criteria; • the structure’s location and orientation on the site; and • other planned or existing site improvements, such as retaining walls, access roads, parking lots, and underground utilities.

Typical changes that could erode the reliability of this report include those that affect:• the site’s size or shape;• the function of the proposed structure, as when it’s changed from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;• the elevation, configuration, location, orientation, or weight of the proposed structure;• the composition of the design team; or• project ownership.

As a general rule, always inform your geotechnical engineer of project changes – even minor ones – and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered.

This Report May Not Be ReliableDo not rely on this report if your geotechnical engineer prepared it:• for a different client;• for a different project;• for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations.

Note, too, that it could be unwise to rely on a geotechnical-engineering report whose reliability may have been affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If your geotechnical engineer has not indicated an “apply-by” date on the report, ask what it should be, and, in general, if you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying it. A minor amount of additional testing or analysis – if any is required at all – could prevent major problems.

Most of the “Findings” Related in This Report Are Professional OpinionsBefore construction begins, geotechnical engineers explore a site’s subsurface through various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing were performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgment to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ – maybe significantly – from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team from project start to project finish, so the individual can provide informed guidance quickly, whenever needed. DRAFT

This Report’s Recommendations Are Confirmation-DependentThe recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgment and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions revealed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation.

This Report Could Be MisinterpretedOther design professionals’ misinterpretation of geotechnical-engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a full-time member of the design team, to: • confer with other design-team members, • help develop specifications, • review pertinent elements of other design professionals’ plans and specifications, and • be on hand quickly whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction observation.

Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for informational purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report, but they may rely on the factual data relative to the specific times, locations, and depths/elevations referenced. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may

perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect.

Read Responsibility Provisions CloselySome client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Geoenvironmental Concerns Are Not CoveredThe personnel, equipment, and techniques used to perform an environmental study – e.g., a “phase-one” or “phase-two” environmental site assessment – differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. As a general rule, do not rely on an environmental report prepared for a different client, site, or project, or that is more than six months old.

Obtain Professional Assistance to Deal with Moisture Infiltration and MoldWhile your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, none of the engineer’s services were designed, conducted, or intended to prevent uncontrolled migration of moisture – including water vapor – from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists.

Copyright 2016 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any

kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent

Telephone: 301/565-2733e-mail: [email protected] www.geoprofessional.org

DRAFT

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