B08_Attach_1_SOW_EX_1_Project_Specifications_Doyle_Fire_Station.pdf

U.S. BUREAU OF LAND MANAGEMENT

SUSANVILLE/DOYLE FIRE STATION

Intersection of US 395 and Doyle Grade Rd.

Doyle, CA

CONTRACT NO. 140L0621D0006

TASK ORDER NO. 140L0621F0431

DOCUMENTS FOR CONSTRUCTION

Project Manual

U.S. DEPARTMENT OF THE INTERIOR

BUREAU OF LAND MANAGEMENT

March 17, 2023

PAGE LEFT BLANK ON PURPOSE

TABLE OF CONTENTS

DIVISION SECTION TITLE

DIVISION 00 – PROCUREMENT AND CONTRACTING REQUIREMENTS

00 01 07 SEALS PAGE

00 01 15 LIST OF DRAWINGS

00 31 32 GEOTECHNICAL DATA

DIVISION 01 – GENERAL REQUIREMENTS

01 10 00 SUMMARY

01 23 00 ALTERNATIVES

01 31 00 PROJECT MANAGEMENT AND COORDINATION

01 32 00 CONSTRUCTION PROGRESS DOCUMENTATION

01 33 00 SUBMITTAL PROCEDURES

01 40 00 QUALITY REQUIREMENTS

01 50 00 TEMPORARY FACILITIES AND CONTROLS

01 57 23 TEMPORARY STORMWATER POLLUTION CONTROLS

01 60 00 SUBSTITUTION PROCEDURES

01 73 00 EXECUTION

01 74 19 CONSTRUCTION WASTE MANAGEMENT AND DISPOSAL

01 77 00 CLOSEOUT PROCEDURES

01 78 23 OPERATION AND MAINTENANCE DATA

01 78 39 PROJECT RECORD DOCUMENTS

01 79 00 DEMONSTRATION AND TRAINING

01 81 13.14 SUSTAINABLE DESIGN REQUIREMENTS

01 91 13 GENERAL COMMISSIONING REQUIREMENTS

DIVISION 02 – EXISTING CONDITIONS

02 41 19 SELECTIVE DEMOLITION

DIVISION 03 – CONCRETE

03 20 00 CONCRETE REINFORCEMENT

03 30 00 CAST-IN-PLACE CONCRETE

03 53 00 CONCRETE TOPPING

DIVISION 04 – MASONRY

04 20 00 UNIT MASONRY

DIVISION 05 – METALS

05 12 23 STRUCTURAL STEEL

05 21 00 STEEL JOISTS

05 31 00 STEEL DECK

05 40 00 COLD FORM STEEL FRAMING (CFSF) SYSTEM

05 50 00 METAL FABRICATION

05 52 10 SAFETY GATES AND RAILINGS

DIVISION 06 – WOODS, PLASTICS AND COMPOSITES

06 10 00 ROUGH CARPENTRY

06 12 00 STRUCTURAL INSULATED PANELS

06 16 00 SHEATHING

06 18 00 GLUED LAMINATED CONSTRUCTION

06 41 16 PLASTIC-LAMINATE-CLAD ARCHITECTURAL CABINETS

DIVISION 07 – THERMAL AND MOISTURE PROTECTION

07 11 13 BITUMINOUS DAMNPROOFING

07 13 26 SELF-ADHERING SHEET WATERPROOFING

07 14 16 COLD FLUID-APPLIED WATERPROOFING

07 21 00 THERMAL INSULATION

07 25 00 WEATHER BARRIERS

07 26 00 VAPOR RETARDERS

07 27 19 SELF-ADHERING AIR BARRIERS

07 27 26 FLUID APPLIED MEMBRANE AIR BARRIERS

07 27 36 SPRAY FOAM AIR BARRIERS

07 42 13.13 FORMED METAL WALL PANELS

07 46 46.10 FIBER CEMENT SIDING

07 48 00 RAINSCREEEN ATTACHMENT SYSTEM

07 60 00 FLASHING AND SHEET METAL

07 61 14.00 20 STEEL STANDING SEAM ROOFING

07 72 00 ROOF ACCESSORIES

07 81 00 SPRAY-APPLIED FIREPROOFING

07 84 13 PENETRATION FIRESTOPPING

07 92 00 JOINT SEALANTS

DIVISION 08 – OPENINGS

08 11 13 HOLLOW METAL DOORS AND FRAMES

08 12 13 HOLLOW METAL FRAMES

08 14 16 FLUSH WOOD DOORS

08 36 13 SECTIONAL DOORS

08 54 13 FIBERGLASS WINDOWS

08 62 50 TUBULAR DAYLIGHTING DEVICES

08 71 00 DOOR HARDWARE

08 80 00 GLAZING

08 87 00 WINDOW FILM

08 91 16 OPERABLE WALL LOUVERS

08 91 19 FIXED LOUVERS

DIVISION 09 – FINISHES

09 22 00 SUPPORTS FOR PLASTER AND GYPSUM BOARD

09 29 00 GYPSUM BOARD

09 30 13 CERAMIC AND PORCELAIN TILING

09 30 50 TILE SETTING MATERIALS AND ACCESSORIES

09 51 13 ACOUSTIC PANEL CEILINGS

09 65 13 RESILIENT BASE AND ACCESSORIES

09 66 00 STATIC CONTROL FLOORING

09 91 13 EXTERIOR PAINTING

09 91 23 INTERIOR PAINTING

09 93 00 STAINING AND TRANSPARENT FINISHING

DIVISION 10 – SPECIALTIES

10 14 23 PANEL SIGNAGE

10 14 26 POST AND PANEL SIGNAGE

10 26 00 WALL AND DOOR PROTECTION

10 28 00 TOILET, BATH, AND LAUNDRY ACCESSORIES

10 44 13 FIRE PROTECTION CABINETS AND WALL MOUNTING BRACKETS

10 44 16 FIRE EXTINGUISHERS

10 51 00 LOCKERS

10 73 00 METAL AWNINGS AND CANOPIES

DIVISION 12 – FURNISHINGS

12 21 13 HORIZONTAL LOUVER BLINDS

12 24 13 ROLLER WINDOW SHADES

12 36 61.16 SOLID SURFACING COUNTERTOPS

12 48 13 FLOOR MATS AND FRAMES

12 93 00 SITE FURNISHINGS

DIVISION 22 – PLUMBING

22 02 00 GENERAL PLUMBING REQUIREMENTS

22 03 00 ELECTRICAL EQUIPMENT AND WIRING COORDINATION FOR

PLUMBING SYSTEMS

22 05 17 SLEEVES AND SLEEVE SEALS FOR PLUMBING PIPING

22 05 19 METERS AND GAGESS FOR PLUMBING PIPING

22 05 23 GENERAL-DUTY VALVES FOR PLUMBING PIPING

22 05 48 VIBRATION AND SEISMIC CONTROLS FOR PLUMBING PIPING

AND EQUIPMENT

22 05 53 IDENTIFICATION FOR PLUMBING PIPING AND EQUIPMENT

22 07 19 PLUMBING INSULATION

22 08 00 COMMISSIONING OF PLUMBING

22 10 05 PLUMBING PIPING

22 11 19 DOMESTIC WATER PIPING SPECIALTIES

22 11 23 DOMESTIC WATER PUMPS

22 15 13 GENERAL-SERVICE COMPRESSED-AIR PIPING

22 15 19 GENERAL-SERVICE PACKAGED AIR COMPRESSORS AND

RECEIVERS

22 33 00 ELECTRIC DOMESTIC-WATER HEATERS

22 40 00 PLUMBING FIXTURES

22 47 00 DRINKING FOUNTAINS AND WATER COOLERS

DIVISION 23 – HEATING, VENTIATION AND AIR CONDITIONING

23 02 00 BASIC HVAC REQUIREMENTS

23 03 00 ELECTRICAL EQUIPMENT AND WIRING COORDINTION FOR

HVAC EQUIPMENT

23 05 13 COMMON MOTOR REQUIREMENTS FOR HVAC EQUIPMENT

23 05 48 VIBRATION AND SEISMIC CONTROLS FOR HVAC PIPING AND

EQUIPMENT

23 05 53 IDENTIFICATION FOR HVAC PIPING AND EQUIPMENT

23 05 93 TESTING, ADJUSTING, AND BALANCING FOR HVAC

23 07 13 DUCT INSULATION

23 08 00 COMMISSIONING OF HVAC

23 09 13 INSTRUMENTATION AND CONTROL DEVICES FOR HVAC

23 09 23 DIRECT DIGITAL CONTROL SYSTEM FOR HVAC

23 11 26 FACILITY LIQUEFIED-PETROLEUM GAS PIPING

23 23 00 REFRIGERANT PIPING

23 31 00 HVAC DUCTS AND CASINGS

23 33 00 AIR DUCT ACCESSORIES

23 34 23 HVAC POWER VENTILATORS

23 34 39 HIGH-VOLUME, LOW-SPEED FANS

23 37 00 AIR OUTLETS AND INLETS

23 37 23 HVAC GRAVITY VENTILATORS

23 55 33 FUEL-FIRED UNIT HEATERS

23 72 23 PACKAGED AIR-TO-AIR ENERGY-RECOVERY UNITS

23 81 27 SMALL SPLIT-SYSTEM HEATING AND COOLING

23 81 29 VARIABLE REFRIGERANT FLOW HVAC SYSTEMS

23 82 00 CONVECTION UNITS

23 82 10 TERMINAL HEATING UNITS

DIVISION 26 – ELECTRICAL

26 05 00 BASIC ELECTRICAL REQUIREMENTS

26 05 03 THROUGH PENETRATION FIRESTOPPING

26 05 13 WIRE AND CABLE

26 05 23 MANUFACTURED WIRING SYSTEMS

26 05 26 GROUNDING AND BONDING

26 05 27 SUPPORTING DEVICES

26 05 33 CONDUIT AND BOXES

26 05 42 EQUIPMENT WIRING SYSTEMS

26 05 48 SEISMIC REQUIREMENTS FOR EQUIPMENT AND SUPPORTS

26 05 53 ELECTRICAL IDENTIFICATION

26 05 73 POWER SYSTEM STUDY

26 09 33 LIGHTING CONTROL SYSTEMS

26 24 16 PANELBOARDS

26 27 16 CABINETS AND ENCLOSURES

26 27 26 WIRING DEVICES

26 28 13 FUSES

26 28 16 DISCONNECT SWITCHES

26 36 00 TRANSFER SWITCH

26 41 00 LIGHTING PROTECTION SYSTEMS

26 43 00 SURGE PROTECTION DEVICES

26 51 19 LED LIGHTING

DIVISION 27 – COMMUNICATIONS

27 05 00 BASIC COMMUNICATIONS SYSTEMS REQUIREMENTS

27 05 03 THROUGH PENETRATION FIRESTOPPING

27 05 28 INTERIOR COMMUNICATION PATHWAYS

27 05 43 EXTERIOR COMMINICATION PATHWAYS

DIVISION 28 – ELECTRONIC SAFETY & SECURITY

28 31 02 FIRE ALARM AND DETECTION SYSTEMS

DIVISION 31 – EARTHWORK

31 10 00 SITE CLEARING

31 20 00 EARTH MOVING

31 21 13 RADON MITIGATION

DIVISION 32 – EXTERIOR IMPROVEMENTS

32 12 16 ASPHALT PAVING

32 13 13 CONCRETE PAVING

32 14 13 PRECAST CONCRETE PAVERS

32 15 00 AGGREGATE SURFACING

32 31 13 CHAIN LINK FENCES & GATES

32 39 13 SURFACE MOUNT METAL BOLLARDS

32 93 00 PLANTS

DIVISION 33 – UTILITIES

33 10 00 WATER UTILITIES

33 30 00 SANITARY SEWER UTILITIES

SUSANVILLE/DOYLE FIRE STATION SEALS PAGE

00 01 07 - 1

DOCUMENT 00 01 07 SEALS PAGE

SUSANVILLE/DOYLE FIRE STATION

BLM PROJECT NO. 140L0621F0431

CONTRIBUTING AUTHORS FOR SPECIFICATIONS

CIVIL ENGINEERING

Brian Christ S&B Christ CA # C76063 Consulting

STRUCTURAL ENGINEERING

Kyle A. Jackson IMEG

CA # C86070

ARCHITECTURE

John Schaaf S&B Christ CA # C37507 Consulting

MECHANICAL/PLUMBING ENGINEERING

Spencer Britton S&B Christ CA # C39020 Consulting

ELECTRICAL ENGINEERING

Mark Zappanti IMEG

CA # E21344

LANDSCAPE ARCHITECTURE

Brad Lents Spurlock CA #5766 Landscape Architects

END OF DOCUMENT 00 01 07

SUSANVILLE/DOYLE FIRE STATION LIST OF DRAWING SHEETS

00 01 15 - 1

DOCUMENT 00 01 15 LIST OF DRAWING SHEETS

GENERAL

G-101 COVER PAGE

G-102 INDEX OF DRAWINGS

G-103 CODE ANALYSIS & GENERAL INFORMATION

CIVIL

C-001 LEGEND AND ABBREVIATIONS

C-100 DEMO PLAN

C-101 SITE PLAN

C-102 GRADING PLAN

C-103 GRADING SECTIONS

C-104 UTILITY PLAN

C-105 GEOMETRIC CONTROL

C-106 LINE AND POINT TABLES

C-107 SUB SLAB DEPRESSURIZATION PLAN

C-200 SITE DETAILS

C-201 UTILITY DETAILS

C-202 FENCE DETAILS

C-203 CIVIL DETAILS

LANDSCAPE

L-100 HARDSCAPE PLAN

L-101 HARDSCAPE DETAILS

L-102 HARDSCAPE DETAILS

L-201 PLANTING PLAN

L-202 PLANTING DETAILS

STRUCTURAL

S-001 GENERAL NOTES

S-002 GENERAL NOTES

S-003 GENERAL NOTES

S-004 GENERAL NOTES

S-005 GENERAL NOTES

S-006 GENERAL NOTES

S-101 FOUNDATION PLAN

S-102 LEVEL 1 MEZZANINE FRAMING PLAN

S-111 ROOF FRAMING PLAN

S-201 FOUNDATION SECTIONS

S-202 TYPICAL SECTIONS AND SCHEDULES

S-203 TYPICAL SECTIONS

S-301 FRAMING SECTIONS

00 01 15 - 2

S-302 FRAMIING SECTIONS

S-401 CMU WALL ELEVATIONS

ARCHITECTURE

AG101 ARCHITECTURAL GENERAL NOTES & MATERIALS

AG102 ARCHITECTURAL LEGENDS & ABBREVIATIONS

AG105 DOOR TYPES

AG106 WINDOW TYPES

AG107 PARTITION TYPES

AG108 CASEWORK TYPES

AG109 SIGNAGE DETAILS

A-101 LEVEL 1 NOTES PLAN

A-102 LEVEL 1 MEZZANINE NOTES PLAN

A-103 LEVEL 1 DIMENSION PLAN

A-111 ROOF PLAN

A-131 LEVEL 1 CEILING PLAN

A-201 EXTERIOR BUILDING ELEVATIONS, N. & S.

A-202 EXTERIOR BUILDING ELEVATIONS, E. & W.

A-301 BUILDING SECTIONS, N. & S.

A-302 BUILDING SECTIONS, E. & W.

A-311 EXTERIOR WALL SECTIONS

A-312 EXTERIOR WALL SECTIONS

A-321 EXTERIOR WALL SECTIONS

A-322 EXTERIOR HEAD AND SILL DETAILS

A-401 ENLARGED PLANS

A-402 ENLARGED PLANS

A-403 ENLARGED STAIR PLANS

A-411 INTERIOR CASEWORK ELEVATIONS

A-412 INTERIOR PLUMBING AREA ELEVATIONS

A-501 EXTERIOR DETAILS

A-502 INTERIOR DETAILS

A-503 CEILING DETAILS

A-504 ROOF DETAILS

A-505 STAIR & RAILING DETAILS

PLUMBING

PG001 NOTES AND LEGEND

P-101 PLAN

P-201 WATER PLAN

P-202 SANITARY PLAN

P-501 DETAILS

P-701 SCHEDULES

00 01 15 - 3

MECHANICAL

MG001 NOTES AND LEGEND

M-101 PLANS I

M-102 PLANS II

M-501 DETAILS I

M-502 DETAILS II AND CALCULATIONS

M-701 SCHEDULES

ELECTRICAL

E-001 ELECTRICAL COVER SHEET

E-100 ELECTRICAL SITE PLAN

E-200 ELECTRICAL POWER PLAN

E-201 ELECTRICAL SYSTEMS PLAN

E-202 ELECTRICAL POWER AND SYSTEMS PLAN - MEZZANINE

E-203 ENLARGED POWER PLAN

E-204 LIGHTNING PROTECTION PLAN

E-300 ELECTRICAL LIGHTING PLAN

E-301 ENLARGED OFFICE LIGHTING PLAN

E-302 ELECTRICAL LIGHTING PLAN - MEZZANINE

E-303 ELECTRICAL COMCHECK

E-400 ELECTRICAL ONE-LINE DIAGRAM

E-500 ELECTRICAL SCHEDULES

E-501 ELECTRICAL SCHEDULES

E-502 ELECTRICAL PANEL SCHEDULES

E-600 ELECTRICAL DETAILS

E-601 LIGHTNING PROTECTION DETALS

END OF DOCUMENT 00 01 15

SUSANVILLE/DOYLE FIRE STATION GEOTECHNICAL DATA

00 31 32 - 1

DOCUMENT 00 31 32 GEOTECHNICAL DATA

This section contains the geotechnical data collected and used to guide the Susanville/Doyle Fire Station Design and construction. The data attached to this section includes:

1. BLM – Doyle Fire Station Geotechnical Report (UES No. 4030.2100272.0000) dated 3/11/2022 performed by Universal Engineering Services (UES).

2. BLM – Doyle Fire Station Percolation Geotechnical Letter (UES No.

4030.2100272.0000) dated July 12, 2022 performed by Universal Engineering Services on the 7th and 8th of July, 2022.

END OF DOCUMENT 00 31 32

UES No. 4030.2100272.0000 Bureau of Land Management

3/11/2022

BLM – Doyle Fire Station Geotechnical Report

S&B Christ Consulting, LLC March 11, 2022 9555 Hillwood Drive, Suite 160 Las Vegas, Nevada 89143

Attn: John Christ, Ph. D., P.E., ENV SP

Re: Design Level Geotechnical Report Bureau of Land Management – Doyle Fire Station Doyle Grade Road and Doyle Drive Doyle, California UES Project Number: 4030.2100272.0000

Dear Mr. Christ, Universal Engineering Sciences (UES) is pleased to submit this geotechnical exploration and engineering report for the BLM Doyle Fire Station Project. Our services consisted of research, field exploration, laboratory testing, and engineering analysis. As presented in the attached report and based on our exploration, knowledge of the project area, and understanding of the project, we conclude that the project site is suitable for the intended use from a geotechnical standpoint.

The attached report presents our understanding of the project, outlines our scope of services, and provides geotechnical recommendations to assist in developing the project. We appreciate the opportunity to provide our services and trust that the results fulfill the project requirements at this time. If you or any of your design consultants have any questions or comments, do not hesitate to get in touch with us.

Respectfully, Universal Engineering Sciences

Laura Varone Martin D. Jensen, P.E.

Staff Geotechnical Professional Principal Engineer

UES Project: 4030.2100272.0000 Doyle Fire Station

Table of Contents

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Proposed Development

2.2 Site Description

3.0 GEOLOGIC AND SEISMIC HAZARDS

3.1 Regional Geology

3.2 Site Geology and Soil Mapping

3.3 Well Log Inquiry and Groundwater

3.4 Faulting and Surface Rupture

3.5 Seismically Induced Liquefaction

3.6 Radon

4.0 GEOTECHNICAL EXPLORATION

4.1 General Surface Characteristics

4.2 Subsurface

5.0 EARTHWORK RECOMMENDATIONS

5.1 Site Clearing and Demolition

5.2 Excavation

5.3 Subgrade Preparation

5.4 Fill Placement and Compaction

5.4.1 Fill Materials

5.4.2 Trench Backfill

6.0 DESIGN RECOMMENDATIONS

6.1 Seismic Site Class and Seismic Design Parameters

6.2 Foundations

6.2.1 Footing Recommendation

6.2.2 Settlement

6.3 Retaining Walls

6.3.1 Lateral Earth Pressures

6.4 Permanent Slopes

6.5 Civil Flatwork Recommendations

6.6 Pavement Recommendations

6.6.1 General Pavement Recommendations

6.7 Concrete Slabs

6.7.1 Recommendations for Concrete Type Based on Soil Corrosivity

7.0 OTHER SERVICES

8.0 CLOSURE

APPENDIX A Plate No.

Exploration Map ......................................................................................................... A-1 Geology Map ............................................................................................................. A-2

APPENDIX B Plate No.

Exploration Photographs ............................................................................................. B-1 Boring Logs ................................................................................................... B-2 and B-4 Key to Symbols..……………………………….………………..….….……..……….………………………….B-5

APPENDIX C Plate No.

Particle Size Distribution Report ...................................................................... C-1 and C-3 Compaction Test……………………….………………………….………………………………….…….…..…C-4 Direct Shear Test…..………………….………………………….………………………………….…….…..…C-5 California Bearing Ratio……….…….………………………….………………………………….…….…..…C-6 Corrosion Report……………………….………………………….………………………………….…….…..…C-7 Seismic Data…………………….………………………………………………….…….…..…C-8 through C-10

GEOTECHNICAL EXPLORATION REPORT

BLM DOYLE FIRE STATION

DOYLE, LASSEN COUNTY, CALIFORNIA

APN: 141-22050-11

1.0 INTRODUCTION

This report presents the results of our geotechnical exploration for the proposed expansion of an existing fire station that will include building a new fire station, equipment storage for hazardous material, tools, and supplies. This project is located on the southwest corner of Doyle Grade, and Doyle Drive in Doyle, Lassen County, California, APN: 141-220-50-11. The site’s general location is shown on Plate A-1, Exploration Map.

The purpose of our services is to provide information and preliminary geotechnical engineering recommendations relative to:

• Subsurface soil conditions

• General geology and seismicity of the area

• Site classification and seismic design parameters

• Earthwork

• Drainage and moisture protection

• Utility trench backfill

• Foundation design and construction

• Retaining wall design and construction

• Concrete slab on grade design and construction

• Pavement design and construction

• Corrosion

This report provides the results of our geotechnical exploration and includes geotechnical engineering design recommendations to assist in developing the proposed project. At the time of writing, no structural loading information was available.

2.0 PROJECT INFORMATION

Our understanding of the project is based on communication with the client and the civil engineering team, a review of the tentative development map, site visits, and geotechnical exploration.

2.1 PROPOSED DEVELOPMENT

As we understand, from emails and phone calls with the client and drawings received on parcel layout and roads, the proposed includes:

• Demolition of existing structures

• Construction of a new, 7,860 square feet fire station

• Construction of new equipment and hazmat storage facilities

• Relocation of propane tank

• Appurtenant construction includes o Flexible asphalt concrete (AC) and rigid Portland cement concrete (PCC) pavements o Modular storage staging area o A new powered sliding gate with indicator light o Designed landscaping and civil flatwork (e.g., sidewalks, curbs and gutters, pavement) throughout the site

• UES assumes cuts and fills less than two feet to achieve the final design grade

UES assumes the new fire station will consist of a pre-engineered metal building with peripheral buildings being a combination of conventional wood-framed, steel-framed, and masonry construction. Further, we assume that all structures will be supported on shallow foundation systems, including spread footing, continuous strip, and concrete slab-on-grade floors.

Structural loadings, grading plans, and anticipated traffic volumes were unavailable at the time of this report.

2.2 SITE DESCRIPTION

According to the Public Land Survey System (PLSS), the project site is located in the NW¼ of the NW¼ of section 17, T25N, R17E of the Mount Diablo Principal Meridian. Further, according to the Lassen County Assessor’s office, the project site is identified as Assessor’s Parcel Number (APN):

141-220-50-11 and consists of 2.47441 acres. Doyle Grade Road borders the project site to the north and Lassen County 361 borders the east. There is undeveloped land to the west of the site and commercial buildings to the south. The project site is accessible via Doyle Drive (Lassen County 361) from the east (Figure 1). The site is generally located at Latitude: 40.026811°, Longitude: -120.104932°, with a mean elevation of 4,275 feet (NAD 83).

3.0 GEOLOGIC AND SEISMIC HAZARDS

As part of the geotechnical exploration of the project site, UES reviewed published geotechnical, geological, and hazard data. The following sub-sections present our findings along with our conclusions.

3.1 REGIONAL GEOLOGY

The site is located in the northern section of Upper Long Valley, a structural basin. This basin is bounded to the north by the Honey Lake Sink, to the west by the Diamond Mountains (a subrange of the Great Sierra Nevada Mountain Range), and to the east by the Virginia Mountains of the Basin and Range. This basin is transitional between the Basin and Range physiographic province to the east and the Sierra Nevada to the west. The area's geologic structure is characterized by high-angle extensional normal faults trending in a north-northeast direction. The Upper Long Valley and Honey Lake Sink are down-dropped grabens with neighboring horsts to the east and west. The present topography of the basin is due primarily to a combination of extensional normal faulting and Quaternary-age basinal sedimentation.

3.2 SITE GEOLOGY AND SOIL MAPPING

According to the geologic mapping by P.A. Lydon, T.E. Gay Jr., and C.W. Jennings (Geologic Map of California, Westwood Sheet, 1960), the materials in the general site vicinity are composed of Qal – Alluvium. A map showing the local geology is presented on Plate A-2, Geologic Map.

Figure 1: Ariel imagery of the site showing current development of subject site (Google EarthPro, 2022).

3.3 WELL LOG INQUIRY AND GROUNDWATER

The United States Geological Survey (USGS) groundwater watch website (https://groundwaterwatch.usgs.gov) shows that the approximate depth to monthly median water level is 195 feet below existing grade (BEG). The nearest well is approximately 10 miles west/northwest of the site. Due to seasonal variations, irrigation practices, and groundwater withdrawal/recharge cycles, groundwater levels fluctuate. Groundwater was encountered at thirty feet in boring two. Based on the information and our exploration, we believe the groundwater does have the potential to affect the construction of the proposed development.

3.4 FAULTING AND SURFACE RUPTURE

Based on a review of the United States Geological Survey (USGS) Quaternary Fault and Fold database and the referenced geologic map, there are two fault zones within 2 miles to the east of the project site. These zones are listed below:

• Honey Lake Fault Zone o 0.6 miles to the east/northeast o Strike N 47 W - 1.0 – 5.0 mm/year o Latest Quaternary (<15 ka)

• Fort Sage Fault Zone o 1.25 miles to the east/northeast o Strike N 19 W - 0.2 mm/year o Historical (1950)

In our opinion, surface fault rupture is likely in the Fort Sage Fault Zone; the seismic design parameters take this fault into account. However, surface rupture at the project site is considered unlikely.

Active faults that generate large magnitude earthquakes have been identified within the region.

The project site is in the Basin and Range Physiographic Province, structurally characterized by high-angle extensional normal faults. Therefore, strong ground shaking associated with earthquakes should be expected during the project’s life.

3.5 SEISMICALLY INDUCED LIQUEFACTION

Liquefaction is a loss of soil shear strength that may occur during a seismic event and results from a buildup of pore water pressures caused by cyclic shear stresses exceeding the effective soil stress. When the pore ware pressures exceed the soil’s effective stress, the soil may behave like a non-Newtonian fluid, subject to three-dimensional ground movement. This phenomenon is limited to poorly consolidated (typically, soils with a shear wave velocity less than 600 feet per second, and Standard Penetration Test (SPT) less than 30) clean to silty sand/sandy silt lying below the groundwater table (typically less than 50 feet deep). The consequences of liquefaction include substantial loss of soil strength, seismic settlement, horizontal ground displacement from lateral spreading, increased lateral soil loads, sand boils, and bearing capacity degradation.

UES conducted a refraction microtremor seismic survey (ReMi) to establish the seismic site classification and liquefaction screening and analysis. The results of the ReMi survey indicate the project site soils are very dense soil and soft rock with an average shear wave velocity of 1,407 feet per second (ft/s). Based on the shear wave velocity and the soil type encountered below the water table – UES concludes that the risk of liquefaction for the proposed development is unlikely.

3.6 RADON

Radon, a colorless, odorless, radioactive gas derived from the natural decay of uranium, is found in nearly all rocks and soils. The Environmental Protection Agency (EPA) suggests taking remedial action to reduce radon in any structure with an average indoor radon level of 4.0 pCi/L or more.

According to the Environmental Protection Agency (EPA) data, Lassen County is in Zone 3 for Radon zones. The area has a low potential with a predicted average indoor radon screening level of less than 2.00 pCi/L. Our office can be of assistance if you desire radon testing.

4.0 GEOTECHNICAL EXPLORATION

Our scope of services includes a geophysical site evaluation, exploration of the near-surface soils (i.e., exploratory borings), and laboratory testing of representative soil samples. UES contracted with Taber Drilling to drill five (5) borings to an approximate depth of 15 to 40 feet BEG using a CME 55 drill rig. A UES staff geotechnical engineer observed and logged the exploration and collected representative soil samples for laboratory testing. The exploration logs are shown in Appendix B. In addition, the approximate locations of the subsurface explorations are shown on Plate A-1, Exploration Map. Soil samples were cataloged, sealed to prevent moisture loss, and returned to UES's Reno, Nevada laboratory for testing. All tests were conducted according to the governing ASTM standard or other regionally recognized standards. Additionally, UES provided one sample to a registered analytical laboratory for chemical and corrosivity analysis. Lab results are provided in Appendix C.

UES’s geophysical site exploration included a Refraction Microtremor (ReMi) survey. The ReMi survey was performed to determine the seismic site class per the IBC 2018 and ASCE 7-16 using the weighted-average soil shear wave velocity for the upper 100 feet (Vs100). Additionally, the ReMi survey provides essential information for the screening and analysis of liquefaction. The ReMi survey recorded both active and ambient seismic noise using 12 10-Hz geophones at an eight-meter (8m,

26.25 ft) spacing for a total survey length of 289-feet. Active noise was generated by striking a 16-pound sledgehammer off the ReMi array’s ends and ambient noise from traffic and walking along the survey line during data acquisition. The ReMi data were acquired using a Seismic Source model

DAQlink4 24-channel seismograph, while data was processed using Geogiga’s Surface Plus application.

4.1 GENERAL SURFACE CHARACTERISTICS

Based on our site visit, historical Google Earth imagery, and our document review; we present the following observations:

• The site has minimal topographic relief with a minimum elevation of approximately 4,285 feet above mean sea level (MSL) near the northeast corner. A maximum elevation of about 4,302 feet MSL in the northwest, based on the NAVD88 vertical datum

• The site is currently developed with crew quarters building and engine bay building o A paved parking lot is surrounding the buildings

• The west side of the site is roughly graded and used for heavy equipment parking o There are a couple of storage sheds and an office module

• The office module building has a sewer tank behind it

• Landscaping borders the buildings along the west side with trees and vegetation

• Site photographs are shown in Figure 2

4.2 SUBSURFACE

UES observed stratified soil through all three borings, the layers varied between poorly graded clayey silty sand (SC-SM), silty sand (SM), and poorly graded sand (SP). In boring three, located in

Figure 2: Top Left: Current buildings and paved parking lot. Bottom left: Landscaping on the west side of the property. Top Right: Back of the office module and storage sheds. Bottom Right: Roughly graded parking lot.

the paved parking lot there was a thin layer sandy silt (ML) encountered at approximately one and half feet. Auger refusal was encountered at twenty-five feet in boring one and at forty and half feet in boring two; both borings were located on the west side where the new fire station is proposed.

In situ dynamic penetration testing was conducted using Standard Penetration Test (SPT) and recorded as blow counts at all sampling intervals. The boring logs report that the in-situ soils are of medium density.

Groundwater was encountered in boring 2, at approximately 35 feet. Groundwater levels are rarely stable and often fluctuate based on environmental and water use practices.

Borings were backfilled with the excavated soil using the available equipment. The approximate locations of the subsurface explorations are shown on Plate A-1, Exploration Map.

5.0 EARTHWORK RECOMMENDATIONS

All earthworks shall be performed according to the guidelines presented in Chapter 18 of the 2018 IBC and the California Building Code 2019, except where this report’s site-specific engineering recommendations are provided. We recommend that all contractors perform their own reconnaissance of the site to verify the conditions reported. If the contractors have questions regarding site conditions, site preparation, or the recommendations of this report, they should contact a Universal Engineering Sciences representative for clarification.

Foundation soils should generally not be allowed to become saturated during or after construction, except when necessary to increase moisture contents before construction. Infiltration of water into foundation or utility excavations should be prevented during construction. Utility lines should be properly installed and the backfill properly compacted to avoid possible sources for subsurface saturation.

Positive drainage away from the structures should be provided during construction and maintained throughout the structures’ life. In addition, the backfill against footings, exterior walls, and utility trenches should be compacted appropriately and free of all construction debris to reduce the possibility of moisture infiltration.

The performance of the foundation system recommended in this report is dependent on the ability to keep moisture from penetrating the soils below foundations and slabs. Therefore, we recommend the following:

• Positive drainage should be maintained away from the structures, adjoining concrete slabs, and block walls. Per the California Building Code section 1804.4 Site Grading: Positive drainage of at least 5% shall be maintained for areas adjacent to structures or block walls not covered by concrete or asphalt.

• Positive drainage should be extending for at least 10 feet from structures, adjoining concrete slabs, and block walls. If physical obstructions or lot lines prohibit 10 feet of horizontal distance, the slope should be provided to an approved alternative drainage method.

• Landscaping adjacent to structural areas should be limited and consist of native vegetation utilizing drip-type irrigation. Sealed planters should be considered for these areas.

• Watering should be kept to a minimum.

5.1 SITE CLEARING AND DEMOLITION

To prepare the project site for construction, UES recommends removing any loose or disturbed surface soil, demolition debris, and vegetation; we anticipate approximately needing to remove between 0.5 and 1.0 feet of surface soils. These materials should be removed from five feet of plan view; they may be placed in landscaped areas and non-structural fills. Care should be taken to prevent the concentration of buried vegetation; over time, the deposits of vegetation will decompose and lead to localized surface and soil irregularities. Therefore, we recommend removing the cleared and grubbed vegetation from the project site. The upper foot of the exposed soil should be screened of all materials greater than six inches (6”) in any direction and compacted to recommendations contained in this report.

• Demolition and site preparation shall include the removal of all foundations, walls, slabs, pavements, walkways, buried structures and drain lines, utilities, pipes, and unsuitable material within the project area. Excavations caused by removal of existing foundations and sewage facilities shall be cleared of all waste, debris, and loose soil, and refilled with compacted fill. All fill compaction should be performed in accordance with the earthwork section of the above referenced report, under observation and testing by the Geotechnical Engineer.

• Foundation demolition includes complete removal of all building foundation walls, footings, slabs, and any other abandoned on-grade and below-grade construction. Broken concrete and other foundation materials shall be considered waste and shall be removed from the site.

• Any existing drain lines, pipes, wires, conduits, utilities, etc., which are to remain on the site shall be protected from damage. Buried drain lines, pipes conduits, utilities, etc., which are necessarily cut shall be either carefully and permanently capped at the property line or re-routed as indicated on the drawings. Utility lines not specifically noted for disposition, but which are encountered in the work shall be capped, extended, protected, or re-worked as necessary for completion of the work as directed.

• All work shall be performed in accordance with the Federal Occupational Safety and Health Administration and the Division of Occupational Safety and Health requirements and applicable ordinances of the governing municipality.

• Care shall be taken not to damage adjoining utilities, sidewalks, or pavements to remain after completion of the work. Finished work damaged by operations during demolition and site preparation shall be repaired or replaced to the satisfaction of the Owner at no cost to the Owner.

• All materials resulting from demolition and site preparation not designated by the Owner to be recovered or to be relocated by the Contractor shall be removed promptly and disposed of off the site.

• Upon completion of demolition and site preparation, the site shall be “raked clean” and all waste, rubble, debris, etc. shall be removed and disposed of off the site.

We recommend that all exposed surfaces be free of mounds and depressions. A uniform surface free of mounds and depressions helps ensure uniform compaction, building conditions, and settlements.

All trash, abandoned utilities, construction debris ruminate, or other deleterious materials exposed or created during the site preparation shall be removed from the site.

5.2 EXCAVATION

In general, we believe this site can be developed using appropriately sized conventional earthwork equipment.

• Excavation, trenching, and shoring should be conducted in accordance with the U.S.

Department of Labor Occupational Safety and Health Administration’s (OSHA) Excavation and Trenching Standard, Title 29 of the Code of Federal Regulation (CFR), Part 1926.650. The safety of construction personnel is the responsibility of the contractor.

• Contractors, especially those excavating for utilities, should satisfy themselves regarding the hardness of materials and equipment required.

• It is anticipated that excavation of the on-site native soils for the proposed project can be accomplished with conventional earthmoving equipment.

• Temporary construction excavations should be sloped or shored. A maximum of slope 1.5:1 (horizontal to vertical) should be applied to all temporary slopes; slopes may need to be flattened depending on conditions exposed during construction. Exposed slopes should be kept moist (but not saturated) during construction.

• If there is not enough space for sloped excavations, shoring should be used. Traffic and surcharge loads should not be allowed within 10 feet of the excavation’s top.

• Materials greater than 12 inches are considered oversized and are not allowed within five feet below the foundations and building pads.

• The oversized material could be removed by screening or by raking the pad area prior to compaction. The owner should determine which method or how much removal is practical and acceptable.

5.3 SUBGRADE PREPARATION

All subgrade soils beneath a proposed structure and five feet beyond in plan view shall be sacrificed a minimum of 12-inches and shall be moisture conditioned to near optimum (±2%) and compacted to a minimum of 90 percent maximum dry density as determined by ASTM D1557.

The resulting surface shall be free of mounds and depressions greater than one inch.

5.4 FILL PLACEMENT AND COMPACTION

After performing the required excavations, the exposed materials should be carefully observed to verify the removal of all unsuitable deposits. If fills are used as part of the new project, we recommend the following:

• All required fills should be placed on a horizontal plane and placed in loose lifts. Lift thickness depends on the contractor’s ability to consistently demonstrate their ability to achieve the compaction requirements outlined in this report. In general, we recommend soils be placed in loose lifts of eight to ten inches (8 – 10”).

• Fills should contain a sufficient soil matrix for compaction of soil around oversize material and prevent oversize material nesting and the creating of soil voids.

• All fills should be compacted to a minimum of 95 percent relative compaction and within two percent of optimum moisture content as determined by ASTM D1557 to reduce secondary settlement of the entire body of the fill.

• Oversized materials (i.e., material greater than six inches in any direction) should not be allowed within two feet (2’) of any structural element (e.g., footings, pavements, slabs)

• Aggregate base layers shall be moisture conditioned to near optimum (±2%) moisture content and compacted to a minimum of 95 percent relative compaction determined by ASTM D1557.

• Care should be taken to maintain the moisture content of the clayey silty sand soils; the in-situ moisture content shall be maintained to minimize volumetric changes. For example, any significantly dried or cracked soils could be wetted until they reach acceptable moisture contents, or they could be excavated and replaced with acceptable properly compacted fill.

• Fills should be observed and tested as necessary to determine compliance with the compaction requirements presented in this report. In general, one compaction test should be performed for approximately every 1,000 cubic yards of fill, one for one foot of fill placed, or material change.

Localized pockets of highly expansive soils should be excavated and replaced with materials meeting the fill specification provided in this report.

5.4.1 Fill Materials

In general, the on-site soils are suitable for supporting the buildings and pavement sections. If needed, imported materials should meet the criteria provided in Table 1. Structural fill criteria are for materials placed beneath buildings, PCC slabs, bituminous pavement, and all other components subject to structural loading. The geotechnical engineer may approve other fill materials.

Table 1: Specifications for fill soils Sieve Size (ASTM C136) Percentage by Weight Passing 4-inch 100 ¾-inch 70-100 No. 40 15-65 No. 200 5-20 Additional Requirements Plasticity Index 15 MAX Liquid Limit 40 MAX Sulfate Content 0.1% MAX Organic Content 1.0% MAX

• We recommend a representative soil sample of any proposed imported fill material be collected and tested to document compliance with these specifications.

• Rocks larger than 12-inches in the greatest dimension shall not be allowed without the approval of the engineer. Fills within two feet of any structural element shall not have oversized materials (i.e., rocks greater than six inches in any direction)

• Imported material should be compatible with on-site soils in addition to being suitable for its intended use. The geotechnical firm should approve all imported materials providing testing during construction prior to importing.

5.4.2 Trench Backfill

The Earthwork Contractor must comply with the “Safety and Health Regulations for Construction” as directed by the Occupational Safety and Health Act (OSHA Standards, Volume III, Part 1926, Subpart P) while excavating and backfilling. The Earthwork Contractor is also responsible for providing a competent person to ensure excavation safety as defined by OSHA standards. UES considers the project type soils an OSHA Soil Type C based on medium dense sand encountered throughout the borings. Therefore, the maximum allowable slope for excavations less than 20-feet deep is 1.5:1 (H:V) or 34°. UES strongly suggests that all earthwork and trench contractors conduct a trench-specific evaluation to determine safe working conditions.

Pipe bedding and trench backfill materials should be moisture conditioned to near optimum (±2%) and compacted to 90 percent relative compaction, or local requirements, based on the maximum dry density determined by ASTM D1557. The thickness of all lifts shall be restricted to a maximum of 8 inches (loose) and individually tested unless the Earthwork Contractor can demonstrate their ability to achieve the required compaction with a thicker looser lift.

Surface stormwater run-off should be prevented from infiltrating into utility trenches. As such, lean concrete should be used for manhole collars to minimize infiltration at these points.

For corrosion protection, where steel or metal pipes are proposed, we recommend that the contractor follow the pipe manufacturer’s recommendation regarding corrosion protection.

6.0 DESIGN RECOMMENDATIONS

Our recommendations assume that soil conditions throughout the project site are similar to those disclosed by our exploration. If variations are noted during construction or if changes are made in the site plan, structural loading, foundation type, or floor level, we should be notified to supplement our recommendations, as applicable.

6.1 SEISMIC SITE CLASS AND SEISMIC DESIGN PARAMETERS

To establish Site Class, we performed a Refraction Microtremor (ReMi) survey. They indicate a weighted-average soil shear wave velocity of the upper 100 feet (Vs100) as 1,407 ft/s, resulting in the designation of a Seismic Site Class C, according to Table R301.2.2.1.1. Then using the established seismic site class UES obtained the project site’s seismic design parameters using the ATC Hazards by Location website (https://hazards.atcouncil.org/). The ATC Hazards by Location website is a third-party graphical user interface (GUI) that utilizes the USGS seismic design maps to provide site-specific seismic design parameters according to ASCE/SEI 7-16. Design parameters are presented in the following table.

Table 2: 2018 IBC Seismic Design Parameters

Description Value Latitude 40.0269 Longitude -120.1059 Site Class C Short-Period (0.2 sec) Spectral Response, SS 1.670 g Long-Period (1.0 sec) Spectral Response, S1 0.567 g Short (0.2 sec) Design Spectral Response, SDS 1.336 g Long (1.0 sec) Design Spectral Response, SD1 0.542 g

In addition, if the proposed structure has a fundamental period of greater than 0.5 seconds, we recommend conducting a site-specific response analysis for structural design. The ReMi survey and analysis are presented on Plates C-8 through C-10.

6.2 FOUNDATIONS

Shallow foundations shall be designed and constructed per local building codes and IBC 2018 Sections 1808 and 1809.

The construction of shallow foundations shall occur on verified compacted fill soils. Supporting soils must be free of mounds and depressions to ensure uniform compaction and support for the foundation system. Materials greater than 6-inches are not recommended on the surface of the native supporting soils. When fills are used to support a foundation system, materials greater than 6-inches are not permitted 24-inches below the foundation system’s base. Fill materials must conform to the recommendations provided in this report’s Fill Materials section.

6.2.1 Footing Recommendation

• The minimum depth of all footings is 20 inches, based on the Susanville Municipal Code,

15.04.110 Amendments

• All footings must be a minimum of 12 inches wide

• Foundations, established as recommended, may be designed to impose a net dead-plus live-load pressure of 2,500 pounds per square foot (psf), with a one-third increase for wind or seismic loads

• After footing excavation, scarify, moisture conditions, and compact twelve inches (12”) of the resulting subgrade

6.2.2 Settlement

Assuming structural loads are typical of the identified construction methods, our geotechnical recommendations are adhered to, along with proper construction quality controls – we do not anticipate total settlement as a primary geotechnical concern. Settlement of the proposed structure(s), supported as recommended, should be within acceptable limits of less than 1-inch total settlement and less than ½-inch of differential settlement. This report’s recommendations must be adhered to if the long-term serviceability and preference expectations are met. If structural loading information is provided to UES, we can, if required, provide updated recommendations.

6.3 RETAINING WALLS

The recommendations provided in this report are only applicable to retaining walls less than 20-feet or two stories. For walls greater than 20-feet or two stories, the soil-structure interaction and dynamic loading assumptions have a significant impact on the loading conditions. Under these circumstances, a site and wall-specific geotechnical study are recommended.

6.3.1 Lateral Earth Pressures

We recommend the design parameters presented in Table 3 and Table 4.

Table 3: Retaining wall design parameters

Soil Parameter Value Soil Unit Weight 125 pcf Internal Angle of Friction 32° Cohesion 0 psf Coefficient of Friction 0.39

Table 4: Lateral earth pressure recommendations, assuming vertical wall back face

Loading Condition Lateral Earth Coefficient

Equivalent Fluid Pressures Units

Horizontal backfill K0 .47 59 psf Ka .31 38 psf Kp 3.25 407 psf/ft

*Passive pressures should not exceed a maximum of 4,000 psf. A one third (1/3) increase may be used for wind or seismic loads

If the retaining wall is constrained and prevented from lateral movement (e.g., basement walls, loading docks), the at-rest equivalent fluid pressure should be used for design instead of the active equivalent fluid pressure. The prevention of lateral movement does not allow sufficient soil displacement for the activation of the active forces. Therefore, restrained retaining walls should be designed using the at-rest (K0) pressure.

For static conditions, the lateral earth pressures on a retaining wall increase linearly from the surface, resulting in triangular force distribution. Therefore, the resultant of the static lateral earth pressures acting on the retaining wall at a point H/3 from the base of the wall (H = retaining wall height).

6.4 PERMANENT SLOPES

As UES understands the project, no permanent slopes are planned at the project site. However, if plans change, please get in touch with our office so we can provide additional recommendations for the construction of permanent slopes.

6.5 CIVIL FLATWORK RECOMMENDATIONS

In order to provide a uniform bearing surface beneath the civil flatwork and to minimize the potential for differential settlement, we recommend the following:

• Scarify, moisture conditions, and compact eight inches (8") of the flatwork subgrade

• Compacted soil beneath foundation elements shall be free of all material greater than 4" in any direction

• Backfill soils shall meet the requirements of this report and be placed in loose lifts of eight to ten inches (8 - 10") in height

• Backfilled soils shall be moisture conditioned to near optimum (±2%) and compacted to a minimum of 95% relative compaction as determined by ASTM D1557

6.6 PAVEMENT RECOMMENDATIONS

Before placing any asphalt or base materials, the pavement area subgrade soils should be prepared according to the Report's Earthwork section recommendations. A pavement section's life and performance depend on numerous factors, including, but not limited to, type and volume of traffic, drainage conditions, and maintenance program. Therefore, we recommend implementing a long-term maintenance plan that includes periodic seal coating, crack sealing, and patching to increase pavement life.

Based on an anticipated heavy traffic volume, Table 5. provides our minimum pavement recommendations. Which include a minimum of twelve-inch (12") properly compacted subgrade soils. Laboratory test results of the CBR-Value are provided on Plate C-6.

Table 5: Potential pavement design profiles

Aggregate Roads* Flexible Pavements Rigid Pavements

Material Type Thickness [in] Thickness [in] Thickness [in] Plantmix Asphalt Surface 5 - Portland Cement Concrete (PCC) - - 6 Aggregate Base, Class 2 8 8 6 Compacted Subgrade 12 12 12

Note: *For aggregate roads, UES recommends a biaxial geogrid between the compacted subgrade and aggregate base.

6.6.1 General Pavement Recommendations

The performance of the pavement can be enhanced by minimizing excess moisture reaching the subgrade soils. The following recommendations should be followed, where possible:

• A polymer-modified asphalt oil, such as PG64-28NV, can be considered. The primary benefit of this oil type is improved rutting resistance, and secondarily, less thermal (cold temperature) cracking and overall improved mixture durability. Additionally, some modified binders provide improved stripping (moisture drainage) resistance.

• Proper drainage of the paved areas should be provided to increase the pavement life. The Site should be graded a minimum of 2% away from the pavements.

• To minimize or prevent moisture migration to subgrade soils, landscaped areas should have cutoff walls/moisture barriers adjacent to pavement areas.

• Consideration should be given to using “desert” landscaping and minimizing watering to help prevent surface run-off.

• Periodic seal coating, crack sealing, and patching of the pavement may be required.

The Earthwork Contractor shall ensure that field density tests have been performed to document the relative compaction of at least the upper 12 inches of pavement subgrade beneath the aggregate base section. Preparation of the native soils shall be documented before placement of structural fill or aggregate base. All subgrades shall be compacted to a smooth, non-yielding surface before placement of aggregate base. Aggregate base sections shall be compacted to a smooth, non-yielding surface before the placement of pavement sections.

6.7 CONCRETE SLABS

The American Concrete Institute (ACI 302) recommendations for slabs-on-grade should be complied with for all concrete placement and curing operations. Northeastern California is a region with relatively low humidity, and consequently, concrete flatwork is prone to shrinking and curling.

Improper curing techniques, excessive water-cement ratios, or inadequate quality control measures can result in random cracking, excessive shrinkage, or slab curling. The use of control joints and reinforcements shall be utilized to help mitigate any damage resulting from the curing of the concrete slabs.

All concrete slabs shall be supported by a minimum six-inch (6") layer of Class 2 aggregate base. As per the California Building Code 2019, Section 1908.3, coarse aggregate shall not exceed ¾ inch. The aggregate base layer serves as a leveling course between the subgrade and concrete slab. Additionally, the required aggregate layer is a critical element of the concrete slab's structural capacity. The structural engineer shall perform the design of the building's floor slab. For concrete slabs founded on a properly compacted Class 2 aggregate base, a coefficient of subgrade reaction (k-value) of 300 pounds per cubic inch (300 pci) should be used.

The aggregate base layer shall be moisture conditioned to near optimum (±2%) and compacted to a minimum of 95 percent relative compaction determined by ASTM D1557. The aggregate base layer should be moistened before the placement of concrete.

If the potential for a damp floor slab is a concern, moisture protection should be provided by a relatively impervious vapor barrier/retarder placed beneath interior slabs.