Attachment C_Project Manual.pdf

MARCH 21, 2025

Eidos Project No. 24005

PROJECT MANUAL

City of Englewood Offi ce Improvements

ServiCenter Phase 2

Englewood, Colorado

EIDOS ARCHITECTS, PC

5400 GREENWOOD PLAZA BOULEVARD

GREENWOOD VILLAGE, COLORADO 80111

WWW.EIDOSARCH.COM

1000% Construction Documents Project Manual for:

City of Englewood Utilities Office Improvements Phase 2 - ServiCenter

Englewood, Colorado Eidos Project No. 24005

March 21, 2025

OWNER

City of Englewood Utilities 1000 Englewood Parkway

Englewood, Colorado 80110

ARCHITECTS

Eidos Architects, PC

5400 Greenwood Plaza Boulevard Greenwood Village, Colorado 80111

720-200-0630

MECHANICAL ENGINEERS

The Ballard Group

2525 South Wadsworth Boulevard Suite 200

Lakewood, Colorado 80227 303-988-4514

ELECTRICAL / TECHNOLOGY ENGINEERS

AE Design, Inc.

1900 Wazee Street, #205 Denver, Colorado 80202

303-296-3034

STRUCTURAL ENGINEERS

JVA, Inc.

1319 Spruce Street Boulder, Colorado 80302

303-565-4936

CIVIL ENGINEERS

Kimley-Horn and Associates, Inc.

6200 South Syracuse Way, Suite 300 Greenwood Village, CO 80111

303-228-2332

CITY OF ENGLEWOOD UTILITIES

SERVICENTER SPACE IMPROVEMENTS PROJECT

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- 1 TABLE OF CONTENTS

PROJECT: CITY OF ENGLEWOOD UTILITIES OFFICE IMPROVEMENTS PHASE 2

ServiCenter Space Improvements Project Englewood, Colorado Eidos Project No. 24005

TABLE OF CONTENTS

A. Table of Contents 1-5 B. Geotechnical Report – City of Englewood ServiCenter Additions 1-51 C. Structural Calculations – ServiCenter Office Addition 1-128 D. Specifications

DIVISION 0 – PROCUREMENT AND CONTRACTING REQUIREMENTS

Refer to CMGC Agreement 004133 Bid Form – Cost-Plus-Fee (Single-Prime Contract) 1-6 004313 Bid Security Forms 1 004322 Unit Prices Form 1-2 004336 Proposed Contractors Form 1-2 004363 WIFIA Funding – State Revolving Fund Requirements 1-2 00436301 WIFIA Program – Borrow Guide to Federal Requirements 1-56 00436302 WIFIA Funding – Labor Standards Interview Cover Page 1 00436302 WIFIA Funding - Labor Standards Interview Form 1 00436303 WIFIA Funding – AIS Certification Letter Template 1-3 00436304 Small Business Information Request 1 00436305 COE Utilities – Contractor Set Up 1-2

DIVISION 1 – GENERAL REQUIREMENTS

011000 Summary 1-6 012100 Allowances 1-4 012200 Unit Prices 1-5 012500 Substitution Procedures 1-4 012600 Contract Modification Procedures 1-2 012900 Payment Procedures 1-4 013100 Project Management and Coordination 1-10 013200 Construction Progress Documentation 1-8 013233 Photographic Documentation 1-3 013300 Submittal Procedures 1-9 013516 Alteration Project Procedures 1-8 014000 Quality Requirements 1-8 014200 References 1-9 014339 Mockups 1-6 015000 Temporary Facilities and Controls 1-11 016000 Product Requirements 1-6 017300 Execution 1-9 017700 Closeout Procedures 1-6 017823 Operation and Maintenance Data 1-7 017839 Project Record Documents 1-4 017900 Demonstration and Training 1-5

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- 2 TABLE OF CONTENTS

019113 General Commissioning Requirements 1-20

DIVISION 2 – EXISTING CONDITIONS

024116 Structure Demolition 1-6 024119 Selective Demolition 1-5

DIVISION 3 – CONCRETE

031000 Concrete Forming and Accessories 1-5 032000 Concrete Reinforcing 1-4 033000 Cast-in-Place Concrete 1-24 034900 Glass Fiber Reinforced Concrete (GFRC) 1-8

DIVISION 4 – UNIT MASONRY

042000 Concrete Unit Masonry 1-15

DIVISION 5 – METALS

051200 Structural Steel Framing 1-9 052100 Steel Joist Framing 1-4 053100 Steel Decking 1-6 054000 Cold-Formed Metal Framing 1-9 055000 Metal Fabrications 1-9

DIVISION 6 – WOOD, PLASTIC AND COMPOSITES

061053 Miscellaneous Rough Carpentry 1-4 061600 Sheathing 1-8 064116 Plastic-Laminate-Clad Architectural Cabinets 1-6 066400 Plastic Paneling 1-2

DIVISION 7 – THERMAL AND MOISTURE PROTECTION

071416 Cold Fluid-Applied Waterproofing 1-6 072100 Thermal Insulation 1-5 072600 Underslab Vapor Barrier 1-3 074400 Concrete Faced Panels 1-4 075323 Ethylene-Propylene-Diene-Monomer (EPDM) Roofing 1-11 076200 Sheet Metal Flashing and Trim 1-13 077200 Roof Accessories 1-6 078413 Penetration Firestopping 1-4 078443 Joint Firestopping 1-4 079200 Joint Sealants 1-7 079219 Acoustical Joint Sealants 1-3

079513.13 Interior Expansion Joint Cover Assemblies 1-6

079513.16 Exterior Expansion Joint Cover Assemblies 1-5

DIVISION 8 – OPENINGS

081213 Hollow Metal Frames 1-5 081416 Flush Wood Doors 1-8 083113 Access Doors & Frames 1-3 083613 Sectional Doors 1-8 084113 Aluminum Framed Entrances and Storefronts 1-14

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- 3 TABLE OF CONTENTS

087100 Door Hardware 1-32 088000 Glazing 1-9 088813 Fire-Rated Glazing 1-6

DIVISION 9 – FINISHES

092216 Non-Structural Metal Framing 1-7 092900 Gypsum Board 1-5 093013 Ceramic Tiling 1-8 095113 Acoustical Panel Ceilings 1-4 096513 Resilient Base and Accessories 1-4 096519 Resilient Tile Flooring 1-4 096726 Seamless Trowelled Flooring 1-6 096813 Tile Carpeting 1-7 099123 Interior Painting 1-5 099600 High Performance Coating 1-5

DIVISION 10 – SPECIALTIES

101423.13 Room Identification Signage 1-4

102113.14 Stainless Steel Toilet Compartments 1-6

102600 Wall and Door Protection 1-3 102800 Toilet, Bath, and Laundry Accessories 1-8 104413 Fire Protection Cabinets 1-3 104416 Fire Extinguishers 1-3

DIVISION 11 – EQUIPMENT

113100 Residential Appliances 1-4

DIVISION 12 – FURNISHINGS

122413 Roller Window Shades 1-4

123661.19 Quartz Agglomerate Countertops 1-3

DIVISION 13 – SPECIAL CONSTRUCTION

133419 Metal Building Systems 1-18

DIVISION 22 – PLUMBING

220500 Common Work Results for Plumbing 1-18 220553 Plumbing Identification 1-6 220700 Plumbing Insulation 1-14 221000 Pipes, Valves, and Piping Specialties 1-56 224000 Plumbing Systems 1-42

DIVISION 23 – HEATING VENTILATING AND AIR CONDITIONING

230500 Common Work Results for HVAC 1-21 230548 HVAC Vibration Control 1-7 230553 HVAC Identification 1-9 230593 Testing, Adjusting, and Balancing 1-13 230700 HVAC Insulation 1-19 230923 Temperature Control Systems - DDC 1-41 230993 Sequences of Operation - DDC 1-6

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- 4 TABLE OF CONTENTS

232300 Refrigerant Piping Systems 1-16 233000 Air Distribution 1-67 237300 Air Handling Units 1-14 238100 Electric Heating Terminals 1-9

DIVISION 26 – ELECTRICAL

260500 Common Work Results for Electrical 1-7 260519 Low-Voltage Electrical Power Conductors and Cables 1-8 260526 Grounding and Bonding for Electrical Systems 1-8 260529 Hangers and Supports for Electrical Systems 1-7 260533 Raceway and Boxes for Electrical Systems 1-16 260553 Identification for Electrical Systems 1-10 260913 Electrical Power Monitoring and Control 1-22 260923 Lighting Control Devices 1-5 260933 Central Dimming Controls 1-8 262200 Low-Voltage Transformers 1-7 262416 Panelboards 1-13 262713 Electricity Metering 1-4 262726 Wiring Devices 1-11 262813 Fuses 1-4 264113 Lighting Protection for Structures 1-5 264313 Surge Protection for Low-Voltage Electrical Power Circuits 1-5 265100 Interior Lighting 1-11 265600 Exterior Lighting 1-14

DIVISION 27 – COMMUNICATIONS

270010 Supplemental Requirements for Communications 1-12 270526 Grounding and Bonding for Communications Systems 1-8 270528 Pathways for Communications Systems 1-16 270529 Hangers and Supports for Communications Systems 1-5 270536 Cable Trays for Communications Systems 1-8 270544 Sleeves and Sleeve Seals for Communications Pathways and Cabling 1-4 270553 Identification for Communications Systems 1-7 271116 Communications Racks, Frames, and Enclosures 1-8 271513 Communications Copper Horizontal Cabling 1-13 271523 Communications Optical Fiber Horizontal Cabling 1-9 271533 Communications Coaxial Horizontal Cabling 1-10 274100 Audio Video Systems 1-52

DIVISION 28 – ELECTRONIC SAFETY AND SECURITY

283111 Digital, Addressable Fire Alarm System 1-20

DIVISION 31 – EARTHWORK NOT USED

DIVISION 32 – EXTERIOR IMPROVEMENTS

329100 Planting Preparation 1-6 329200 Turf and Grasses 1-6 329300 Plants 1-7

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- 5 TABLE OF CONTENTS

DIVISION 33 – UTILITIES NOT USED

APPENDICES FOR REFERENCE REGARDING DIV 32 & DIV 33 SPECIFICATIONS NOT INCLUDED

Appendix 1 City of Englewood Design Standards 1-315 Appendix 2 Denver Water Capital Projects Construction Standards Vol. 1 1-666 Appendix 3 Denver Water Capital Projects Construction Standards Vol. 2 1-712 Appendix 4 Denver Water Capital Projects Construction Standards Vol. 3 1-594

CTL|Thompson, Inc.

Denver, Fort Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County – Colorado

Cheyenne, Wyoming and Bozeman, Montana

CITY OF ENGLEWOOD SERVICENTER ADDITIONS

2800 SOUTH PLATTE RIVER DRIVE

ENGLEWOOD, COLORADO

Prepared for:

EIDOS ARCHITECTS, PC

5400 Greenwood Plaza Boulevard

Greenwood Village, Colorado 80111

Attention:

Lori Hanson

Project No. DN52,129.000-125-R1

March 26, 2025

GEOTECHNICAL INVESTIGATION

https://ctlthompson.com/ https://ctlthompson.com/denver https://www.ctlthompson.com/fortcollins https://www.ctlthompson.com/coloradosprings https://www.ctlthompson.com/glenwoodsprings https://www.ctlthompson.com/pueblo https://www.ctlthompson.com/summitcounty https://www.ctlthompson.com/cheyenne https://www.ctlthompson.com/bozeman

Table of Contents

EIDOS ARCHITECTS, PC Page i of ii

CITY OF ENGLEWOOD SERVICENTER ADDITIONS

CTL|T PROJECT NO. DN52,129.000-125-R1

SCOPE

SUMMARY

SITE CONDITIONS

PROPOSED CONSTRUCTION

PREVIOUS INVESTIGATION

INVESTIGATION

SUBSURFACE CONDITIONS

Existing Fill

Natural Soils

Bedrock

Groundwater

GEOLOGIC HAZARDS

Expansive and Compressible Soils

Existing Landfill, Methane and Radioactivity

Seismicity

SITE DEVELOPMENT

Demolition and Existing Undocumented Fill

Sub-Excavation

Excavation

Fill and Backfill

Utilities

Stabilization

GROUND IMPROVEMENT

Vibropiers and Aggregate Piers

Compaction Grouting

FOUNDATIONS

Helical Piles

Footings/Pads

FLOOR SYSTEMS

Slabs-On-Grade

Structurally Supported Floors

Exterior Flatwork

SUBSURFACE DRAINAGE

Table of Contents, Continued

EIDOS ARCHITECTS, PC Page ii of ii

CTL|T PROJECT NO. DN52,129.000-125-R1

PAVEMENTS

CONCRETE

SURFACE DRAINAGE

CONSTRUCTION OBSERVATION

GEOTECHNICAL RISK

LIMITATIONS

FIG. 1 – LOCATIONS OF EXPLORATORY BORINGS

FIG. 2 – SUMMARY OF LOG OF EXPLORATORY BORINGS

FIG. 3 – CONCEPTUAL SUB-EXCAVATION PROFILE

FIGS. 4 AND 5 – FOUNDATION WALL DRAIN DETAILS

APPENDIX A – LABORATORY TEST RESULTS AND TABLE A-I

APPENDIX B – FLEXIBLE AND RIGID PAVEMENT MATERIALS, CONSTRUCTION AND

MAINTENANCE GUIDELINES

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CTL|T PROJECT NO. DN52,129.000-125-R1

SCOPE

This report presents the results of our Geotechnical Investigation for the additions planned to the City of Englewood ServiCenter located at 2800 South Platte River Drive in Eng-lewood, Colorado (Fig. 1). The addition includes a one-story structure with no below-grade ar-eas onto the west side of the existing PEMB Building. The purpose of our investigation was to evaluate the subsurface conditions to provide geotechnical design and construction recommen-dations for the project. The scope was described in our Contract Modification No. DN 23-0347-

CM1 dated June 3, 2024 which was made part of our AIA Agreement dated October 20, 2024.

Our scope did not include evaluation of the property for the presence of potentially hazardous materials (Phase I ESA).

This report was prepared based on site reconnaissance, our understanding of the pro-posed construction and site conditions, subsurface conditions found in our exploratory borings, results of field and laboratory tests, engineering analysis, and our experience. It includes our opinions and recommendations for design criteria and construction details for foundations, floor systems, slabs-on-grade, and drainage precautions. The recommendations presented in the re-port are based on the construction as currently planned. Changes to the construction may re-quire revision of this report and the recommended design criteria. A summary of our conclusions and recommendations follows. Detailed design criteria are presented within the report.

SUMMARY

1. A landfill is mapped along South Platte River Drive and appears to underlay the north part of the addition and the northeast part of the site, as it extends in a swath paralleling about 75 feet off the street. Strata found in our borings gener-ally consisted of about 7 to 12 feet of existing fill and 10 to 34 feet of natural sand, gravel and clay underlain by claystone or sandstone bedrock. In a boring located at the addition, sandstone was found at a depth of about 26 feet (TH-2) or approximate elevation 5309 feet. Our borings penetrated about 5 inches of as-phalt pavement at the surface. Some fill may be natural soil, but this was difficult to discern. We judge the fill/soils in the upper 10 feet are relatively soft/loose and potentially compressible under increases in effective pressure caused by the new construction. The presence of a landfill presents unquantifiable risk of settlement for new improvements.

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CTL|T PROJECT NO. DN52,129.000-125-R1

2. Groundwater was measured at a depths of about 17 and 19 feet or approximate elevations 5249 and 5316 feet. Considering the site proximity to South Platte River, we believe the groundwater is likely influenced by flow in the River.

Groundwater could influence installation of drilled piers, if used, but is not ex-pected to affect construction. Groundwater levels may fluctuate seasonally and rise in response to precipitation, landscape irrigation, changes in land-use and flow in the South Platte River.

3. The presence of compressible soils and an existing landfill constitutes a geologic hazard. There is risk that slabs-on-grade and foundations may experience settle-ment, and subsequent damage. We believe the recommendations presented in this report will help to reduce risk of damage; they will not eliminate that risk.

Slabs-on-grade and, in some instances, foundations may be damaged by soil movements. The risks of soil movements can be reduced, but not eliminated, with proper planning, engineering, design and construction. This site has rela-tively higher risks of soil movements and damage because it is underlain by a landfill.

4. Our boring data indicates there is unquantifiable risk of settlement at this site due to the presence of landfill materials, and likely no practical way to remove and re-place or recompact the materials without underpinning or shoring/bracing. We recommend helical pile foundations bottomed in the relatively dense natural sands and gravels below the landfill. Design and construction criteria are pro-vided in the report. Alternatively, it may be possible to perform compaction grout-ing or vibropier installation to improve the existing fill in-place and reduce poten-tial settlements for shallow footing foundations and slab-on-grade floors. These techniques are commonly used on landfills in the Denver-Metro area. More dis-cussions are presented in the report.

5. Slab-on-grade floors constructed on the existing landfill have unquantifiable risk of settlement and damage. We typically recommend structurally supported floors in finished spaces, or if movement and cracking are not tolerable. If slab-on-grade floors are used, the owner must accept the risk of movement and damage.

Slabs should be isolated from foundations and finishes to prevent transmitting movements to the structure.

6. It is not likely practical to perform sub-excavation to remove the relatively loose materials at depth for pavements and exterior flatwork. At minimum, we recom-mend scarifying pavement/flatwork subgrade to a depth of at least 12 inches and compacting. Sub-excavation to 2-5 feet or more can be considered to enhance performance. Discussions and minimum pavement sections are presented in the report.

7. Surface drainage should be designed, constructed, and maintained to provide rapid removal of runoff away from the building and off pavements and flatwork.

Water should not be allowed to pond adjacent to the building or in pavement or flatwork areas. Area drains can be used in low-slope areas to help collect surface water and reduce risk of wetting.

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CTL|T PROJECT NO. DN52,129.000-125-R1

8. The design and construction criteria in this report were compiled with the expec-tation that all other recommendations presented related to site development, sur-face drainage, landscaping irrigation, backfill compaction, etc. will be incorpo-rated into the project and that the owner will maintain the structure, use prudent irrigation practices and maintain surface drainage. It is critical that all recommen-dations in this report are followed.

SITE CONDITIONS

The City of Englewood ServiCenter is located at 2800 South Platte River Drive in Eng-lewood, Colorado (Fig. 1 and Photo 1). The addition is planned to be about 2,700 square feet attached to the west side of the existing PEMB Building located at the northwest end of the pub-lic works/parks facility. Several structures occupy the site and are surrounded by pavements and flatwork; the PEMB Building is a one-story, metal warehouse building with a slab-on-grade floor, and no below-grade areas. It has vehicle bay doors on the south side. Portions of the west end of the structure may be demolished as part of construction. The site slopes gently to the northwest. According to the City and County of Denver records, the north part of the site is un-derlain by a solid-waste landfill. The landfill is mapped along the South Platte River Drive and appears to underlay the north part of the addition and the northeast part of the site, as it extends in a swath paralleling about 75 feet off the street (Photo 2). The remarks indicate the mapping was done by others reviewing aerial photos from 1949, 1967 or 1971. The landfill contains man-made deposits of earth, rock fragments, and refuse, and includes embankments, dams, and other engineered fills, dump fills and soil banks.

Photo 1: Google Earth Aerial Photograph, September 2023.

Red outline is PEMB Building and Blue outline is proposed addition.

EIDOS ARCHITECTS, PC 4 of 27

Photo 2: Aerial Photograph Showing Locations of Landfills

PROPOSED CONSTRUCTION

The renovation of the existing building will include removal of existing flatwork, interior and exterior walls and pavements. Eisos Architects’ Site Plan AC2.0 (Project Number 23037) indicates an approximate 2,700 square-foot addition is planned on the west side of the existing

PEMB Building. The addition will be a one-story structure with no below-grade areas. Existing pavements may be modified, and new pavements will be added north of the PEMB Building.

The east portion of the building will be converted into two drive-thru bays leading to the pave-ments to the north, and the re-worked material storage area to the northeast. A covered electri-cal vehicle charging area is planned on the east side of the building. Relatively light foundation loads are expected for the addition.

PREVIOUS INVESTIGATION

We performed a Preliminary Geotechnical Investigation under Project No. DN52,129-

115-R1 (report dated January 12, 2024). We drilled and sampled one exploratory boring on the northeast side of the PEMB building and strata consisted of about 7 feet of existing fill and 41 feet of slightly silty, gravelly sand underlain by claystone bedrock (TH-1). A 5-foot-thick clay layer was identified within the sand at a depth of 14 feet. Groundwater was encountered at a

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CTL|T PROJECT NO. DN52,129.000-125-R1

depth of 17 feet. The existing fill was judged to be compressible, and the natural soils as non-expansive. We discussed use of deep foundations for the addition or improvement of the exist-ing fill in-place. The data from the previous investigation was re-used in preparation of this re-port.

INVESTIGATION

We investigated subsurface conditions on October 17, 2024, by drilling and sampling two exploratory borings on the west side of the PEMB Building, at the approximate locations shown on Fig. 1 (i.e., TH-2 and TH-3). TH-1 from our preliminary study was located on the northeast side. Prior to drilling, we contacted the Utility Notification Center of Colorado and local sewer and water districts to identify locations of buried utilities. A private utility locator was also retained. The borings were drilled to a depth of 20 and 30 feet below existing grades using 4-inch diameter, continuous-flight, solid-stem auger and a truck-mounted CME-55 drill rig. We es-timated the boring locations and elevations using a Leica GS18 GPS unit referencing the

NAD83.

Samples were obtained at approximate 2 to 5 feet intervals using a 2.5-inch diameter

(O.D.) modified California barrel sampler or a 2-inch O.D. standard split spoon sampler driven by blows from an automatic 140-pound hammer falling 30 inches. Bulk samples of auger cut-tings from the upper 5 feet were also obtained from each boring. Our field representative was present to observe drilling operations, log the strata encountered, and obtain samples. Upon completion of drilling, hand-slotted PVC pipe was installed in TH-2 to facilitate a delayed groundwater level measurement. TH-3 was backfilled immediately after drilling. TH-2 was back-filled upon checking for delayed water. Graphical summary logs of the exploratory borings, in-cluding results of field penetration resistance tests and a portion of laboratory test results, are presented in Fig. 2.

Samples were returned to our laboratory where they were examined, classified, and as-signed testing. Laboratory tests included moisture content, dry density, particle-size analysis

(gradation and percent silt and clay-sized particles passing the No. 200 sieve), Atterberg limits, swell-consolidation, unconfined compression, and water-soluble sulfate concentration. Swell-consolidation tests were performed by wetting samples under approximate overburden pressure

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CTL|T PROJECT NO. DN52,129.000-125-R1

(the pressure exerted by overlying soils). Laboratory test results are presented in Appendix A and summarized in Table A-I.

SUBSURFACE CONDITIONS

Strata encountered in our exploratory borings generally consisted of about 7 to 12 feet of existing landfill and 10 to 34 feet of natural clean to silty, gravelly sand with sandy clay, and un-derlain by claystone bedrock in TH-1 or sandstone bedrock in TH-2. Our borings penetrated about 5 inches of asphalt pavement at the surface. Some fill may be natural soil, but this was difficult to discern, as their composition and characteristics were similar. Some of the pertinent geotechnical engineering characteristics of the soils and bedrock are described in the following paragraphs.

Existing Fill

We believe we encountered about 9 to 12 feet of fill existing fill at the ground surface in

TH-2 and TH-3; the additional borehole information implies the fill materials in TH-1 could or may extend deeper than our logging of 7 feet, but this is uncertain. The fill consisted of silty to clayey sand with gravel and sandy clay. Based on the results of field penetration resistance tests, the fill is very loose to loose or medium stiff to stiff. One sandy clay fill sample swelled 2.7 percent when wetted under an applied pressure of 200 psf. Seven fill samples contained 25 to

58 percent silt and clay-sized particles and five samples exhibited low to moderate plasticity.

One sample had 4 percent gravel (retained on No. 4 sieve). One fill sample had an unconfined compressive strength of 2,957 psf.

Natural Soils

Natural soils consisted of clean to silty, gravelly sand with occasional clay pockets and lenses. Upper portions of the natural sand may be landfill, but this was difficult to determine.

The sand was medium dense to very dense, excluding a couple of loose sand samples just be-low fill; the clay was medium stiff to stiff. One sandy clay sample contained 73 percent fines and had moderate plasticity. Seven sand samples contained 5 to 49 percent fines and four samples had 17 to 50 percent gravel. A very clayey sand sample showed moderate plasticity.

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Bedrock

We encountered sandy, silty claystone bedrock in TH-1 at a depth of about 41 feet to the northeast of the PEMB Building. Sandstone bedrock was encountered in TH-2 at a depth of 26 feet. The bedrock is considered to be very hard. A sandy claystone sample contained 76 per-cent fines and exhibited moderate plasticity.

Groundwater

Groundwater was found during drilling at depths of about 17 to 19 feet below the existing ground surface. When the test holes were checked after drilling on November 20, 2024, water levels were measured in TH-1 and TH-2 at depths of about 17 and 18.5 feet. Considering the site proximity to South Platte River, we believe the groundwater is likely influenced by flow in the

River. Groundwater could influence installation of drilled piers, if used, but is not expected to af-fect construction. Groundwater levels may fluctuate seasonally and rise in response to precipita-tion, landscape irrigation, changes in land-use and flow in the South Platte River.

GEOLOGIC HAZARDS

Expansive and Compressible Soils

Colorado is a challenging location to practice geotechnical engineering. The climate is relatively dry, and the near-surface soils are typically dry and comparatively stiff. These soils and related sedimentary bedrock formations tend to react to changes in moisture content. Some soils swell as they increase in moisture and are referred to as expansive soils. Other soils can compress significantly and are identified as compressible soils. The soils that exhibit compressi-ble behavior are more likely west of the Continental Divide; however, both types of soils occur throughout the state.

Covering the ground with buildings, pavements, flatwork, etc., coupled with landscape irrigation and changing drainage patterns leads to an increase in subsurface moisture condi-tions. As a result, some soil movement is inevitable. It is critical that all recommendations in this report are followed to increase the chances that the foundations and slabs-on-grade will perform

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CTL|T PROJECT NO. DN52,129.000-125-R1

satisfactorily. Owners and/or property managers must assume responsibility for maintaining structures and use appropriate practices regarding drainage and landscaping.

Based upon the findings of our investigation, we believe compressible materials are pre-sent at depths likely to influence performance of shallow foundations, slabs, pavements, and other surface improvements. The soils show potential to compress or consolidate upon wetting or increases in effective pressures caused by additional loading from the new construction. We recorded relatively loose consistency in the soils in the upper 10 feet from the ground surface.

The presence of compressible soils is considered a geologic hazard. There is risk that ground settlement will damage slabs-on-grade and foundations. The risks can be mitigated, but not eliminated, by careful design, construction, and maintenance procedures. We believe the recommendations in this report will help reduce risk of foundation and/or slab damage; they will not eliminate that risk. Slabs-on-grade and, in some instances, foundations may be affected.

Maintenance will be required to reduce risk.

Existing Landfill, Methane and Radioactivity

We believe the fill is related to the presence of a landfill. We judge the fill to be unsuita-ble to support proposed construction. Ideally, all fill should be removed and recompacted as moisture conditioned, compacted fill as discussed in Fill and Backfill. The presence of the ex-isting PEMB Building likely renders sub-excavation not possible without the need for underpin-ning the existing foundations or shoring/bracing. Therefore, deep foundations are recommended unless the landfill materials can be improved in-place using compaction grouting or vibropiers installation.

Landfills are a major source of methane, a greenhouse gas that contributes to climate change. In 2021, the EPA reported that landfills were the third-largest source of methane emis-sions in the U.S. Methane is also highly flammable and can form explosive mixtures in enclosed spaces. Landfills can contaminate soil and groundwater with heavy metals and other pollutants from the waste. These pollutants can reduce soil fertility and impact plant growth. Environmental aspects were not included in our scope. Typical mitigation methods consist of sealing soil gas entry areas, ventilation of below-grade spaces, and venting from foundation drain systems. We

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CTL|T PROJECT NO. DN52,129.000-125-R1

recommend provision for ventilation of foundation drain systems if radon or other chemical haz-ard is discovered.

It is normal in the Front Range of Colorado and nearby eastern plains to measure radon gas in poorly ventilated spaces (e.g. crawl spaces) in contact with soil. Gases from landfill mate-rials may also be present. Radon 222 gas in considered a health hazard and is just one of sev-eral radioactive products in the chain of the natural decay of uranium into lead. Radioactive nu-clides are common in the soil and bedrock underlying the subject site. Because these sources exist or will exist on most sites in the area, there is a potential for radon gas accumulation in poorly ventilated spaces. The concentration of radon that can develop is a function of many fac-tors, including the radionuclide activity of the soil and bedrock, construction methods and mate-rials, soil gas pathways, and accumulation areas. The only reliable method to determine if a hazard exists is to perform radon testing of completed structures to determine the level of radon gas accumulation. Typical mitigation methods consist of sealing soil gas entry areas, ventilation of below-grade spaces, and venting from foundation drain systems.

Seismicity

According to the USGS, Colorado’s Front Range and eastern plains are considered low seismic hazard zones. The earthquake hazard exhibits higher risk in western Colorado com-pared to other parts of the state. The Denver Metropolitan area has experienced earthquakes within the past 100 years, shown to be related to deep drilling, liquid injection, and oil/gas ex-traction. Naturally occurring earthquakes along faults due to tectonic shifts are rare in this area.

The soil and bedrock at this site are not expected to respond unusually to seismic activity.

Based on our investigation, we judge a Seismic Site Classification of D is appropriate. The sub-surface conditions indicate low susceptibility to liquefaction from a materials and groundwater perspective.

SITE DEVELOPMENT

The primary geotechnical concerns include the presence of relatively loose landfill mate-rials. There is uncertainty on the depth of fill present at this site which may only become discov-erable by excavation on the site to further explore the fill depths and extents. Regardless, our

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CTL|T PROJECT NO. DN52,129.000-125-R1

field penetration resistance data indicates the surficial materials within the upper 10 feet from the ground surface are relatively loose and judged to be compressible.

There is unquantifiable risk of movement for foundations, floor slabs, and other surface improvements. Mitigation techniques, such as sub-excavation or ground improvement, are re-quired to reduce potential settlements and provide more uniform support characteristics. The following discussions present our opinions and recommendations for site development, includ-ing ground improvement to mitigate the geotechnical concerns.

Demolition and Existing Undocumented Fill

Portions of the existing PEMB Building, surrounding flatwork and pavements will be de-molished and removed as part of the proposed construction. Demolition should include the re-moval of all existing structural members (foundations, foundation walls, grade beams, and floor slabs), exterior flatwork, utilities, and backfill associated with the areas being renovated and im-proved. Utilities, structures, and debris should be removed and replaced with moisture condi-tioned, compacted fill. Excavations resulting from removal of these items should be backfilled with clean, moisture conditioned and well-compacted fill capable of supporting the planned loads. Existing fill and backfill presents risk of settlement to floor slabs and other surface im-provements, and should be completely removed below the additions, where present. Clean por-tions of the fill can be reworked and reused as new, moisture conditioned, compacted fill. Envi-ronmental considerations were not within our scope, and can significantly impact the project cost and should be evaluated early in the planning process.

Sub-Excavation

Without mitigation of compressible materials, helical pile foundations and structurally supported floors are required for the addition. If shallow, footing/pad foundations are desired for the addition, we recommend substantially removing and replacing or recompacting the existing fill to reduce potential settlements to acceptable levels, and to provide more uniform support conditions. Care should be taken to avoid undermining existing PEMB Building foundations.

Shoring/bracing or underpinning are likely needed to ensure stability for the existing founda-tions, which are suspected to be footings/pads. We can discuss this further if sub-excavation of the landfill is being considered.

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The existing soils are suitable for re-use as new fill from a geotechnical standpoint, pro-vided they are free of debris, organics/vegetation, and other deleterious materials, and are moisture conditioned and compacted. Sub-excavation should extend at least 5 feet outside the lateral extent of foundations. A conceptual sub-excavation profile is shown on Fig. 3. Provided that the sub-excavation is successful, we estimate potential movements of about 1 inch or less are probable. Differential movements should also be substantially reduced.

In order for the sub-excavation procedure to be performed properly, close control of fill placement to specifications is required. Sub-excavation fill should be placed in loose lifts no thicker than 8 inches, moisture conditioned to within 2 percent of optimum moisture content, and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D698). Our field representative should observe and test compaction of fill during placement.

We have seen isolated instances where settlement of sub-excavation fill has led to dam-age to buildings supported on shallow foundations. In most cases, the settlement was caused by wetting associated with poor surface drainage and/or poorly compacted fill placed at the hori-zontal limits of the sub-excavation. Special precautions should be taken for compaction of fill at corners, access ramps and edges of the sub-excavation due to equipment access constraints.

The contractor should have the appropriate equipment to reach and compact these areas.

The excavation contractor should be chosen based on experience with sub-excavation and processing fills and have the necessary mixing and compaction equipment. The contractor should provide a construction disc to break down fill materials. The operation will be relatively slow. Soil clods should be broken down to about 3 inches or less. The excavation slopes should meet OSHA, state, and local safety standards.

We recommend at least 12 inches of sub-excavation, moisture-conditioning and re-com-paction below pavements to reduce potential heave and improve performance. The sub-excava-tion can be extended beneath the adjacent sidewalks and improvements, if desired. Less sub-excavation (or no sub-excavation) can be considered if risk of movements is acceptable.

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Excavation

We believe the soils penetrated in our exploratory borings can generally be excavated with conventional, heavy-duty excavation equipment. We recommend the owner and the con-tractor become familiar with applicable local, state and federal safety regulations, including the current OSHA Excavation and Trench Safety Standards. We anticipate the fill and soils will clas-sify as Type C soils, which require maximum slope inclinations of 1½H:1V for temporary exca-vations in dry conditions. Flatter slopes will be required if any seepage is present. Loose materi-als may slough into excavations and the contractor should anticipate this. There may be more peripheral distance on this project than typical because of the loose and unknown conditions.

The contractor’s “competent person” is required to review excavation conditions and re-fer to OSHA Standards when worker exposure is anticipated. Stockpiles of soils and equipment should not be placed within a horizontal distance equal to one-half the excavation depth, from the edge of the excavation.

Fill and Backfill

The on-site soils are suitable for reuse as new fill from a geotechnical standpoint, pro-vided they are free of debris, vegetation/organics and other deleterious materials. Soil particles larger than about 3 inches in diameter should not be used for fill unless broken down. Imported fill (if any) should have a maximum particle size of 3 inches, less than 40 percent passing the

No. 200 sieve, a liquid limit less than 30 and a plasticity index less than 15. Potential fill materi-als should be submitted to our office for approval prior to importing.

Prior to fill placement, the ground surface should be scarified to a depth of at least 8 inches, moisture conditioned and compacted to the criteria below. Subsequent fill should be placed in thin (8 inches or less) loose lifts, moisture conditioned to within 2 percent of optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry den-sity (ASTM D698).

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Utilities

Water, storm sewer and sanitary sewer lines are often constructed beneath slabs and pavements. Compaction of utility trench backfill can have a significant effect on the life and ser-viceability of floor slabs, pavements and exterior flatwork. Our experience indicates use of self-propelled compactors results in more reliable performance compared to fill compacted by an at-tachment on a backhoe or trackhoe. The upper portion of the trenches should be widened to al-low the use of a self-propelled compactor. Considering the relative loose, granular sand fill soils predominant in the upper soils to support the new construction, if would be prudent to use vibra-tory compaction equipment on this project.

Special attention should be paid to backfill placed adjacent to manholes as we have ob-served conditions where settlement in excess of 1 percent has occurred after completion of con-struction. Flowable fill may be considered at critical utility crossings where it would be difficult to achieve adequate compaction. Utility trench backfill should be moistened and compacted as dis-cussed in Fill and Backfill. The placement and compaction of utility trench backfill should be observed and tested by a representative of our firm during construction.

Stabilization

Soft/loose soil may slough to slopes of about 6:1 or shallower. This could impact effi-ciency of the contractor’s work. They should be prepared to deal with soft/loose soil conditions.

Soft/loose soils are likely to be encountered in excavations and should be removed or stabilized.

Loose excavation bottoms can be stabilized by crowding crushed rock into the soils until firm.

Acceptable rock materials include, but are not limited to, No. 2 and No. 57 rock or 1 to 3-inch recycled concrete. Crushed rock on a layer of geosynthetic grid or woven fabric can also be used, which should reduce the amount of aggregate needed to stabilize the subgrade. Typically, a biaxially woven fabric such as Mirafi 600x (or equal) or geogrid (such as Tensar TR160 or equal) topped with 8 to 12 inches of crushed rock will provide a stable working surface. If availa-ble, crushed recycled concrete is a good choice. The actual need for, and elements of subgrade stabilization should be determined at the time of construction.

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GROUND IMPROVEMENT

In lieu of using deep foundations and structurally supported floors or sub-excavation at this site, it may be possible to improve the existing landfill and soils in-place using new ground improvement techniques which are gaining popularity in the Denver-Metro area. These are com-paction grouting and vibropier techniques. We have worked with Keller North America on pro-jects with similar applications to achieve tolerable post-construction settlements, including in landfills. These techniques are discussed in more detail in this section.

Vibropiers and Aggregate Piers

Vibropiers, also known as aggregate piers or stone columns, consist of a grid of large-diameter holes which are drilled, and gravel aggregate is rammed or vibrated into each hole, densifying surrounding fill and soils, and creating stiff columns of gravel to reduce differential and total settlement by increasing the overall stiffness of the treated mass. These piers can also be grouted to help transmit loads to deeper, denser materials. The vibratory energy densifies the aggregate and any surrounding soil. The dense aggregate interlocks to form a stiff pier that engages the surrounding soil to provide reinforcement and increased shear resistance. If mer-ited, a 12 to 24-inch thick layer of ¾-inch crushed rock and geogrid is installed below the foun-dations and floor slabs, along the tops of the stone columns, to help span the improved ground.

Based on our investigation, we anticipate treatment depths to 15 to 20 feet below existing grades will be required. The specialty contractor should be consulted with to confirm potential bearing pressures and settlement. Load tests are typically performed at the site to confirm de-sign values and that the desired results are being achieved.

Compaction Grouting

Compaction grouting techniques can be employed to densify the soils in place. Compac-tion grouting involves pumping a low-mobility, aggregate grout to displace and densify the sur-rounding soils. This approach is best suited for soils that are soft to stiff or loose to medium dense, such as the materials encountered. Injection points should be located within improve-ment areas and spaced at 5 to 10 feet on-center. The extent of the grouting will depend on the grout volume and pressure. Based on our investigation, we anticipate grouting to depths of

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CTL|T PROJECT NO. DN52,129.000-125-R1

about 15 to 20 feet below the existing grades will be required. An encapsulation grout layer can also be installed to further help the development span over the treated materials.

To provide a guide specification, the grout should have a maximum slump of 1 inch and should be injected at a volume between 4 to 6 cubic feet per foot. Injection pressures should not exceed 250 psi. We typically prefer a bottom-up grouting procedure. Adjustments may be needed in the field as grouting progresses, depending on actual conditions encountered.

The top of the compaction grout bulbs will be at various elevations relative to founda-tions and finished floor grades in the building. Generally, they are terminated about 1 to 2 feet below the foundation or slab elevations. Sometimes, a geogrid and gravel layer are necessary along the tops of the compaction grout bulbs, to help span and bridge the improved ground. The specialty contractor should be consulted with to confirm potential bearing pressures and settle-ment.

FOUNDATIONS

Our investigation indicates loose, compressible landfill materials are present at depths likely to influence the performance of shallow foundations. The conditions should be mitigated as discussed previously. Provided sub-excavation or ground improvement are successfully per-formed, we believe footing foundations can be used for the building addition. Helical piers and structurally supported floors should be used in lieu of sub-excavation or ground improvement, or if less movement is desired. There is increased risk of movement compared to a deep founda-tion system, even after sub-excavation is performed.

New shallow foundations (if used) along the west portion of the existing PEMB structure will likely be built adjacent to existing footings and pads. We recommend constructing new foot-ings at the same elevations as existing footings to avoid creating surcharge effects. This will likely aid in constructing foundations beneath existing backfill as well. Footings constructed lower than existing foundations may cause undermining and loss of support, and this should be considered in design. The connection between the existing building and new addition should be designed to accommodate up to 1-inch of differential movement.

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Design and construction criteria for helical piles and footing foundations are presented below. The criteria presented below were developed from analysis of field and laboratory data and our experience.

Helical Piles

1. We recommend that the helical piers bottom in the natural sand/gravel soils pre-sent at a depth of about 12-15 feet or deeper. Longer piers may be required for structural loads or to achieve sufficient torque. Total length should be measured from ground surface to the top helix or plate. The piles should be installed as close to vertical as possible or at the angle specified by our structural engineer or manufacturer.

2. Based on the end area of the helix, the total vertical load on the pile should not exceed 6,500 psf. A load test may justify a higher pressure.

3. The ultimate capacity of helical piers should be calculated based on the manu-facturer's recommendations. We recommend calculation of the installation torque using a factor of safety of at least 2 when converting ultimate values to working (allowable) capacity. Helical pier capacity should be confirmed in the field using manufacturer recommended capacity torque ratios. Load tests can be done to verify pile capacity. It may be necessary to need multiple helices to achieve torque.

4. Contractors should use the number and size of helical blades required to achieve depth, torque and capacity.

5. The helical pile cap and the connection between the pile and grade beams/foun-dation walls should be able to resist both tension and compression and be de-signed to resist lateral earth pressure and loads. The structural engineer should design this connection.

6. We recommend contacting the manufacturer or the manufacturer’s representa-tive concerning corrosion protection of the steel. Manufacturer’s recommenda-tions should be followed.

7. Twisting of the shaft can occur during the installation process. The structural en-gineer should evaluate the effect(s) of twisting of the shaft may have on the ca-pacity and the corrosion protection (such as the “flaking off” of the galvanizing material).

8. Installation of helical piers should be observed by a representative of our firm to document the depth and installation of torque of the piles.

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Footings/Pads

1. Footings or pads should be constructed on new, moisture conditioned and com-pacted fill (sited at least 5 feet inside the sub-excavation limits) or landfill im-proved by compaction grouting or vibropiers. Where soils are disturbed during excavation or in the forming process, or if any loose/soft soils are exposed in ex-cavations, the soils should be removed and re-compacted as recommended in Fill and Backfill, or stabilized, prior to placing concrete.

2. After sub-excavation or ground improvement, footing foundations can be de-signed using a maximum allowable soil pressure of 3,000 psf. The specialty con-tractor may merit higher allowable pressure based on the ground improvement technique which is implemented.

3. Lateral earth pressures can be calculated based on equivalent fluid density using at least 35 pcf for the active case. For the at-rest case, where essentially no lat-eral movement is allowed, we recommend using at least 55 pcf. Footing transla-tion can be resisted using an equivalent fluid density of 250 pcf for the passive case, providing backfill is similar to the site soils, is well compacted and remains in-place. The coefficient of friction for sliding may be taken as 0.40. These values have not been factored. The structural engineer should apply appropriate factors of safety in design. Ground improvement techniques will likely improve these val-ues for shallow foundations.

4. Footings should have a minimum width of 16 inches. Foundations for isolated columns should have minimum dimensions of 18 inches by 18 inches. Larger sizes may be required depending upon the loads and structural system used.

5. Foundation walls and grade beams should be well-reinforced. We recommend reinforcement sufficient to span an unsupported distance of at least 10 feet or the distance between pads, whichever is applicable. Reinforcement should be de-signed by the structural engineer considering the effects of lateral loads on the wall performance.

6. Exterior footings must be protected from frost action. Normally, 3 feet of frost cover is assumed in the area.

7. The completed foundation excavations should be observed by a representative of our firm to confirm subsurface conditions are as anticipated. Our representa-tive should observe and test moisture and compaction of the fill and backfill.

8. Excessive wetting of foundation soils during and after construction can cause heave or softening and consolidation of foundation soils and result in footing movements. Proper surface drainage around the building is critical to control wet-ting.

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FLOOR SYSTEMS

Slabs-On-Grade

With the recommended sub-excavation or ground improvement, we estimate potential movements of about 1 inch or less are probable for slab-on-grade floors constructed on im-proved soils. Conventional slab-on-grade floors can be used provided risk of heave and distress is acceptable to the owner. There will likely be distress to the slabs and sensitive finishes. We recommend structurally supported floors if movements cannot be tolerated.

Where conventional slabs-on-grade are used and the owner accepts the risks, we rec-ommend the following design and construction…