geotechnical engineering report - larimer

REPORT COVER PAGE

Geotechnical Engineering Report __________________________________________________________________________

Carter Lake Campground

Loveland, Colorado

February 4, 2020

Terracon Project No. 20195090

Prepared for:

AVI Professional Corporation

Fort Collins, Colorado

Prepared by:

Terracon Consultants, Inc.

Fort Collins, Colorado

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REPORT TOPICS

INTRODUCTION ............................................................................................................. 1 SITE CONDITIONS ......................................................................................................... 1

PROJECT DESCRIPTION .............................................................................................. 2 GEOTECHNICAL CHARACTERIZATION ...................................................................... 2

GEOTECHNICAL OVERVIEW ....................................................................................... 4 EARTHWORK................................................................................................................. 5

SHALLOW FOUNDATIONS ......................................................................................... 11 SEISMIC CONSIDERATIONS ...................................................................................... 12

FLOOR SLABS............................................................................................................. 13 AGGREGATE-SURFACED ROADWAYS .................................................................... 14

CORROSIVITY.............................................................................................................. 16 GENERAL COMMENTS ............................................................................................... 16

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ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLANS

EXPLORATION RESULTS

SUPPORTING INFORMATION Note: Refer to each individual Attachment for a listing of contents.

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Geotechnical Engineering Report

Carter Lake Campground ■ Loveland, Colorado

February 4, 2020 ■ Terracon Project No. 20195090

Responsive ■ Resourceful ■ Reliable i

REPORT SUMMARY

Topic 1 Overview Statement

2

Project Overview

A geotechnical exploration has been performed for the proposed Carter Lake Campground project to be constructed east of Carter Lake and County Road 31 in Loveland, Colorado. Three (3) borings were performed to depths of approximately 4 to 14 feet below existing site grades.

Subsurface Conditions

Subsurface conditions encountered in our exploratory borings generally consisted of about 0 to 5 feet of sandy lean clay to clayey sand with varying amounts of gravel over claystone bedrock. Hard to very hard claystone, sandstone and/or granite bedrock was encountered below the overburden soils in the borings at depths of approximately 2.5 to 7 feet below existing site grades. About 7 feet of weathered claystone was encountered in one of our borings at depths of about 6 inches below existing site grades and extended to Boring logs are presented in the Exploration Results section of this report.

Groundwater Conditions

Groundwater was not encountered in any of our test borings at depths at the time of drilling. Groundwater levels can fluctuate in response to site development and to varying seasonal and weather conditions, irrigation on or adjacent to the site and fluctuations in nearby water features.

Geotechnical Concerns

■ As previously stated, hard to very hard bedrock was encountered at depths of about 2½ to 7 feet below existing site grades. Bedrock levels varied across the site and shallower bedrock could be encountered in some areas. Excavation penetrating the bedrock may require the use of specialized heavy-duty equipment, together with ripping or jack-hammering to advance the excavation and facilitate rock break-up and removal. Consideration should be given to obtaining a unit price for difficult excavation in the contract documents for the project.

■ Gravel, cobbles and boulders were encountered in our borings in the sandy lean clay to clayey sand layer of the subsurface profile. Cobbles and boulders can present challenging excavation conditions and may require the use of specialized heavy-duty equipment to advance the excavation. Where large cobbles or boulders are present in subgrade areas below proposed foundations and concrete slabs, there is risk for potential point loads that could cause cracking of the concrete elements.

■ Expansive soils are present on this site and these conditions constitute a geologic hazard. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and cracking in the structures and flatwork (if any) is possible. The severity of cracking and other damage such as uneven floor slabs and flat work will probably increase if modification of the site results in excessive wetting or drying of the expansive clays. Eliminating the risk of movement and cosmetic distress is generally not feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. It is imperative the recommendations described in section Grading and Drainage section of the Earthwork section of this report be followed to reduce potential movement.

Earthwork

On-site soils typically appear suitable for use as general engineered fill and backfill on the site provided they are placed and compacted as described in this report. Import materials (if needed) should be evaluated and approved by Terracon prior to delivery to the site. Earthwork recommendations are presented in the Earthwork section of this report.




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Topic 1 Overview Statement

2

Grading and Drainage

The amount of movement of foundations, concrete slabs, pavements, etc. will be related to the wetting of underlying supporting soils. Therefore, it is imperative the recommendations discussed in the Grading and Drainage section of the Earthwork section this report be followed to reduce potential movement. As discussed in the Grading and Drainage section of this report, surface drainage should be designed, constructed and maintained to provide rapid removal of surface water runoff away from the proposed structures and roadway. Water should not be allowed to pond adjacent to foundations or on roadways and conservative irrigation practices should be followed to avoid wetting foundation/slab soils and roadway subgrade. Excessive wetting of foundations/slab soils and subgrade can cause movement and distress to foundations, floor slabs, concrete flatwork (if any) and roadways.

Foundations

The proposed pavilion and other planned structures such as the vaulted toilet building, trash enclosure, etc. can be supported by a shallow, spread footing foundation system. Design recommendations for foundations for the proposed structure and related structural elements are presented in the Shallow Foundations section of this report.

Floor Systems

We believe a concrete slab-on-grade floor system can be used for the proposed pavilion and vaulted toilet building provided the soils are over-excavated to a depth of at least 12 inches below the proposed floor slab and replaced with moisture conditioned, properly compacted engineered fill. On-site soils are suitable as over-excavation backfill below floor slabs. Design recommendations for floor slabs for the proposed structure and related structural elements are presented in the Floor Slabs section of this report.

Roadways

Design of aggregate-surfaced roadways for the project has been based in general accordance with the “Aggregate-Surfaced Road Design Catalog” subsection of the 1993 AASHTO “Guide for the Design of Pavement Structures” and based on subsurface conditions encountered at the site and laboratory test results. Recommended minimum roadway sections for this project include 9 inches of aggregate base course over properly prepared roadway subgrade.

Seismic Considerations

As presented in the Seismic Considerations section of this report, the International Building Code, which refers to Section 20 of ASCE 7, indicates the seismic site classification for this site is C.

Construction Observation and Testing

Close monitoring of the construction operations and implementing drainage recommendations discussed herein will be critical in achieving the intended foundation, slab and roadway performance. We therefore recommend that Terracon be retained to monitor this portion of the work.

General Comments

This section contains important information about the limitations of this geotechnical engineering report.

1. If the reader is reviewing this report as a pdf, the topics (bold orange font) above can be used to access the appropriate section of the report by simply clicking on the topic itself.

2. This summary is for convenience only. It should be used in conjunction with the entire report for design making and design purposes. It should be recognized that specific details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein.


INTRODUC TION


Carter Lake Campground

East of Carter Lake on County Road 31

Loveland, Colorado Terracon Project No. 20195090

February 4, 2020

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering

services performed for the proposed Carter Lake Campground project to be located east of Carter

Lake on County Road 31 in Loveland, Colorado. The purpose of these services is to provide

information and geotechnical engineering recommendations relative to:

■ Subsurface soil and rock conditions ■ Foundation design and construction

■ Groundwater conditions ■ Floor system design and construction

■ Site preparation and earthwork ■ Seismic considerations

■ Excavation considerations ■ Lateral earth pressures

■ Roadway design and construction

The geotechnical engineering scope of services for this project included the advancement of three

(3) test borings to depths ranging from approximately 4 to 14 feet below existing site grades.

Maps showing the site and boring locations are shown in the Site Location and Exploration

Plan sections, respectively. The results of the laboratory testing performed on soil and bedrock

samples obtained from the site during the field exploration are included on the boring logs and as

separate graphs in the Exploration Results section of this report.

SITE CONDITIONS

The following description of site conditions is derived from our site visit in association with the

field exploration and our review of publicly available geologic and topographic maps.

Item Description

Parcel Information

The project site is located north of the intersection of County Road 31 and

West County Road 82 on the east side of Carter Lake Reservoir in Loveland,

Colorado. The approximate Latitude/Longitude of the center of the site is

40.33802° N/105.20929°W (Please refer to Site Location).

Existing

Improvements The site is currently occupied by vacant land and some improved roadways.





Item Description

Surrounding

Developments

In general, the site is surrounded by vacant land with some single-family

homes. The site is bordered to the west by County Road 31 followed by

existing campgrounds and Carter Lake Reservoir.

Current Ground

Cover The site appears to be covered in native grasses and weeds.

Existing Topography The site is relatively flat with some rolling hills and sloped areas.

PROJECT DESCRIPTION

Our final understanding of the project conditions is as follows:

Item Description

Information Provided

The following project information was provided to us on a site plan prepared

by Larimer County Engineering Department, dated December 2019, modified

December 23, 2019.

Project Description We understand the project includes the construction of a new campground on

the east side of Carter Lake Reservoir.

Proposed

Construction

The project includes three circular drives with 5 campground sites around

each circle. Campground sites include a RV site, picnic table, fire pit and

elevated tent pad. The project also includes an access road connecting

campground sites, a trash enclosure, vault toilets, a pavilion, proposed

playscape area/natural experience area and new underground utilities.

Grading/Slopes We anticipate minor cuts and fills on the order of 5 feet or less will be required

to achieve proposed grades.

Below-grade

Structures We understand no below-grade are planned for this site.

Roadways We assume aggregate-surface roadways will be used in the proposed project.

If project information or assumptions vary from what is described above or if location of

construction changes, we should be contacted as soon as possible to confirm and/or modify our

recommendations accordingly.

GEOTECHNICAL CHARACTERIZATION

Subsurface Profile

We have developed a general characterization of the subsurface conditions based upon our

review of the subsurface exploration, laboratory data, geologic setting and our understanding of

the project. This characterization, termed GeoModel, forms the basis of our geotechnical

calculations and evaluation of site preparation and foundation options. Conditions encountered at





each exploration point are indicated on the individual logs. The individual logs and GeoModel can

be found in the Exploration Results section of this report.

Model Layer Layer Name General Description Approximate Depth to

Bottom of Stratum

- Vegetative

Layer

Sandy lean clay with some clay/granite fragments, dark brown/black with light gray.

About 6 inches below existing site grades.

1 Lean clay

Sandy lean clay to clayey sand with

gravel, fine to coarse grain, areas of

bedrock fragments brown to light brown

with gray, very stiff.

About 2½ to 5 feet below existing site grades.

2 Weathered

Bedrock

Weathered claystone to sandstone, gray

to light gray/white, medium hard.

About 7 feet below existing site grades, only encountered in Boring No 1.

3 Bedrock

Claystone, sandstone and/or granite

bedrock, gray, very hard, caused auger

refusal at 7½ feet in Boring No. 1 and 4

feet in Boring No. 2.

To the maximum depths of exploration of about 4 to 14 feet below existing site grades.

As noted in General Comments this characterization is based upon widely spaced exploration

points across the site and variations are likely.

Groundwater Conditions

The boreholes were observed while drilling and shortly after completion for the presence and level

of groundwater. Groundwater was not observed in the borings while drilling, or for the short duration

the borings could remain open. These observations represent short-term groundwater conditions

at the time of and shortly after the field exploration and may not be indicative of other times or at

other locations. Groundwater levels can be expected to fluctuate with varying seasonal and

weather conditions, and other factors.

Laboratory Testing

A representative soil sample was selected for swell-consolidation testing and exhibited 2.2

percent swell when wetted. Samples of site soils and bedrock selected for plasticity testing

exhibited low to moderate plasticity with liquid limits ranging from 27 to 46 and plasticity indices

ranging from 11 to 23. Laboratory test results are presented in the Exploration Results section

of this report.





GEOTECHNICAL OVERVIEW

Based on subsurface conditions encountered in the borings, the site appears suitable for the

proposed construction from a geotechnical point of view provided certain precautions and design

and construction recommendations described in this report are followed. We have identified

several geotechnical conditions that could impact design, construction and performance of the

proposed structures and other site improvements. These included shallow bedrock, large

cobbles/boulders that could impact excavation and expansive soils. These conditions will require

particular attention in project planning, design and during construction and are discussed in

greater detail in the following sections.

Shallow Bedrock

As previously stated, hard to very hard bedrock was encountered at depths of about 2½ to 7 feet

below existing site grades. Bedrock levels varied across the site and shallower bedrock could

be encountered in some areas. Excavation penetrating the bedrock may require the use of

specialized heavy-duty equipment, together with ripping or jack-hammering to advance the

excavation and facilitate rock break-up and removal. Consideration should be given to obtaining a

unit price for difficult excavation in the contract documents for the project.

Gravel, Cobbles and Boulders

Gravel, cobbles and boulders were encountered in our borings in the sandy lean clay to clayey

sand layer of the subsurface profile. Cobbles and boulders can present challenging excavation

conditions and may require the use of specialized heavy-duty equipment to advance the

excavation. Where large cobbles or boulders are present in subgrade areas below proposed

foundations and concrete slabs, there is risk for potential point loads that could cause cracking of

the concrete elements.

Expansive Soils and Bedrock

Expansive soils are present on this site and these conditions constitute a geologic hazard. This

report provides recommendations to help mitigate the effects of soil shrinkage and expansion.

However, even if these procedures are followed, some movement and cracking in the structures

and flatwork (if any) is possible. The severity of cracking and other damage such as uneven floor

slabs and flat work will probably increase if modification of the site results in excessive wetting or

drying of the expansive clays. Eliminating the risk of movement and cosmetic distress is generally

not feasible, but it may be possible to further reduce the risk of movement if significantly more

expensive measures are used during construction. It is imperative the recommendations

described in section Grading and Drainage section of the Earthwork section of this report be

followed to reduce potential movement.





Foundation and Floor System Recommendations

The proposed pavilion and other planned structures such as the vaulted toilet building, trash

enclosure, etc. can be supported by a shallow, spread footing foundation system. Design

recommendations for foundations for the proposed structure and related structural elements are

presented in the Shallow Foundations section of this report.

We believe a concrete slab-on-grade floor system can be used for the proposed pavilion and

vaulted toilet building provided the soils are over-excavated to a depth of at least 12 inches below

the proposed floor slab and replaced with moisture conditioned, properly compacted engineered fill.

On-site soils are suitable as over-excavation backfill below floor slabs. Design recommendations

for floor slabs for the proposed structures and related structural elements are presented in the

Floor Slabs section of this report.

The General Comments section provides an understanding of the report limitations.

EARTHWORK

The following presents recommendations for site preparation, excavation, subgrade preparation,

fill materials, compaction requirements, utility trench backfill, grading and drainage and exterior

slab design and construction. Earthwork on the project should be observed and evaluated by

Terracon. Evaluation of earthwork should include observation and/or testing of over-excavation,

subgrade preparation, placement of engineered fills, subgrade stabilization and other

geotechnical conditions exposed during the construction of the project.

Site Preparation

Prior to placing any fill, strip and remove existing vegetation, topsoil, and any other deleterious

materials from the proposed construction areas.

Stripped organic materials should be wasted from the site or used to re-vegetate landscaped areas

or exposed slopes after completion of grading operations. Prior to the placement of fills, the site

should be graded to create a relatively level surface to receive fill, and to provide for a relatively

uniform thickness of fill beneath proposed structures.

Excavation

It is anticipated that excavations for the majority of the proposed construction can be accomplished

with conventional earthmoving equipment.

Excavation penetrating the bedrock may require the use of specialized heavy-duty equipment,

together with ripping or jack-hammering to advance the excavation and facilitate rock break-up and





removal. Consideration should be given to obtaining a unit price for difficult excavation in the

contract documents for the project. Relatively deep excavations for underground utilities and the

vault toilet will likely encounter bedrock.

The soils to be excavated can vary significantly across the site as their classifications are based

solely on the materials encountered in widely-spaced exploratory test borings. The contractor

should verify that similar conditions exist throughout the proposed area of excavation. If different

subsurface conditions are encountered at the time of construction, the actual conditions should be

evaluated to determine any excavation modifications necessary to maintain safe conditions.

Although evidence of fills or underground facilities such as grease pits, septic tanks, vaults,

basements, and utilities was not observed during the site reconnaissance, such features could be

encountered during construction. If unexpected underground facilities are encountered, such

features should be removed, and the excavation thoroughly cleaned prior to backfill placement

and/or construction.

Any over-excavation that extends below the bottom of foundation elevation should extend laterally

beyond all edges of the foundations at least 8 inches per foot of over-excavation depth below the

foundation base elevation. The over-excavation should be backfilled to the foundation base

elevation in accordance with the recommendations presented in this report.

Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or

groundwater may be encountered in excavations on the site. It is anticipated that pumping from

sumps may be utilized to control water within excavations.

The subgrade soil conditions should be evaluated during the excavation process and the stability

of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter

than the OSHA maximum values may have to be used. The individual contractor(s) should be

made responsible for designing and constructing stable, temporary excavations as required to

maintain stability of both the excavation sides and bottom. All excavations should be sloped or

shored in the interest of safety following local, and federal regulations, including current OSHA

excavation and trench safety standards.

As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral

distance from the crest of the slope equal to the slope height. The exposed slope face should be

protected against the elements

Subgrade Preparation

After the vegetative layer and top soil has been removed from the construction area, the top 10

inches of the exposed ground surface, bottom of foundation excavation or floor slab excavation

should be scarified, moisture conditioned, and recompacted to at least 95 percent of the maximum





dry unit weight as determined by ASTM D698 before any new fill, foundation or road-surfacing

material is placed.

If pockets of soft, loose, or otherwise unsuitable materials are encountered at the bottom of the

foundation excavations and it is inconvenient to lower the foundations, the proposed foundation

elevations may be reestablished by over-excavating the unsuitable soils and backfilling with

compacted engineered fill or lean concrete.

In addition, large cobbles or boulder-sized materials may be encountered beneath foundation and

concrete slab areas. Such conditions could create point loads on the bottom of foundations,

increasing the potential for differential foundation movement and/or cracking of concrete. If such

conditions are encountered in the foundation excavations, the cobbles and/or boulders should be

removed and be replaced with engineered fill, conditioned to near optimum moisture content and

compacted.

After the bottom of the excavation has been compacted, engineered fill can be placed to bring the

building pads and roadway subgrade to the desired grade. Engineered fill should be placed in

accordance with the recommendations presented in subsequent sections of this report.

The stability of the subgrade may be affected by precipitation, repetitive construction traffic or

other factors. If unstable conditions develop, workability may be improved by scarifying and

drying. Alternatively, over-excavation of wet zones and replacement with granular materials may

be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil

until a stable working surface is attained. Use of fly ash or geotextiles could also be considered

as a stabilization technique. Laboratory evaluation is recommended to determine the effect of

chemical stabilization on subgrade soils prior to construction. Lightweight excavation equipment

may also be used to reduce subgrade pumping.





Fill Materials

The on-site soils or approved granular and low plasticity cohesive imported materials may be used

as fill material. Bedrock excavated during site development and construction can be reused as fill

provided the material is broken down and thoroughly processed to a “soil-like” consistency, with

no particles greater than 2 inches in size. The earthwork contractor should expect significant

mechanical processing and moisture conditioning of the site soils and/or bedrock will be needed

to achieve proper compaction

Imported soils (if required) should meet the following material property requirements:

Gradation Percent finer by weight (ASTM C136)

4” 100

3” 70-100

No. 4 Sieve 50-100

No. 200 Sieve 50 (max.)

Soil Properties Values

Liquid Limit 35 (max.)

Plasticity Index 15 (max.)

Other import fill materials types may be suitable for use on the site depending upon proposed

application and location on the site, and could be tested and approved for use on a case-by-case

basis.

Compaction Requirements

Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures

that will produce recommended moisture contents and densities throughout the lift.

Item Description

Fill lift thickness

9 inches or less in loose thickness when heavy, self-

propelled compaction equipment is used

4 to 6 inches in loose thickness when hand-guided

equipment (i.e. jumping jack or plate compactor) is used

Minimum compaction requirements

95 percent of the maximum dry unit weight as determined by

ASTM D698.

95 percent of the maximum dry unit weight as determined by

ASTM D1557 for aggregate surfacing for roadways

Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content





Item Description

Moisture content cohesionless soil

(sand) -3 to +3 % of the optimum moisture content

1. We recommend engineered fill be tested for moisture content and compaction during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved.

2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be achieved without the fill material pumping when proof rolled.

3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within these materials could result in an increase in the material’s expansive potential. Subsequent wetting of these materials could result in undesirable movement.

Utility Trench Backfill

All trench excavations should be made with sufficient working space to permit construction including

backfill placement and compaction.

All underground piping within or near the proposed structures should be designed with flexible

couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts

in foundation walls should be oversized to accommodate differential movements. It is imperative

that utility trenches be properly backfilled with relatively clean materials. If utility trenches are

backfilled with relatively clean granular material, they should be capped with at least 18 inches of

cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water

through the trench backfill.

Utility trenches are a common source of water infiltration and migration. All utility trenches that

penetrate beneath the structures should be effectively sealed to restrict water intrusion and flow

through the trenches that could migrate below the structures.

It is strongly recommended that a representative of Terracon provide full-time observation and

compaction testing of trench backfill within building and roadway areas.

Grading and Drainage

Grades must be adjusted to provide effective drainage away from the proposed structures during

construction and maintained throughout the life of the proposed project. Infiltration of water into

foundation excavations must be prevented during construction. Landscape irrigation adjacent to

foundations should be minimized or eliminated. Water permitted to pond near or adjacent to the

perimeter of the structures (either during or post-construction) can result in significantly higher

soil movements than those discussed in this report. As a result, any estimations of potential

movement described in this report cannot be relied upon if positive drainage is not obtained and

maintained, and water is allowed to infiltrate the fill and/or subgrade.





Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 5 feet

beyond the perimeter of the proposed structures, where possible. Locally, flatter grades may be

necessary to transition ADA access requirements for flatwork. The use of swales, chases and/or

area drains may be required to facilitate drainage in unpaved areas around the perimeter of the

structures. Backfill against foundations and exterior walls should be properly compacted and free

of all construction debris to reduce the possibility of moisture infiltration. After construction of the

proposed structures and prior to project completion, we recommend verification of final grading

be performed to document positive drainage, as described above, has been achieved.

Flatwork (if any) will be subject to post-construction movement. Maximum grades practical should

be used for paving and flatwork to prevent areas where water can pond. In addition, allowances

in final grades should take into consideration post-construction movement of flatwork, particularly

if such movement would be critical. Where flatwork abuts the structures, care should be taken

that joints are properly sealed and maintained to prevent the infiltration of surface water.

Exterior Slab Design and Construction

Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or

the site soils will likely experience some movement due to the volume change of the material.

Potential movement could be reduced by:

◼ Minimizing moisture increases in the backfill;

◼ Controlling moisture-density during placement of the backfill;

◼ Using designs which allow vertical movement between the exterior features and

adjoining structural elements; and

◼ Placing control joints on relatively close centers.

Construction Observation and Testing

The earthwork efforts should be monitored under the direction of Terracon. Monitoring should

include documentation of adequate removal of vegetation and topsoil, proof rolling, and mitigation

of areas delineated by the proof roll to require mitigation. Each lift of compacted fill should be

tested, evaluated, and reworked as necessary until approved by Terracon prior to placement of

additional lifts.

In areas of foundation excavations, the bearing subgrade should be evaluated under the direction

of Terracon. In the event that unanticipated conditions are encountered, Terracon should

prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the

continuation of Terracon into the construction phase of the project provides the continuity to





maintain Terracon’s evaluation of subsurface conditions, including assessing variations and

associated design changes.

SHALLOW FOUNDATIONS

If the site has been prepared in accordance with the requirements noted in Earthwork, the

following design parameters are applicable for shallow foundations.

Spread Footings - Design Recommendations

Description Values

Bearing material Properly prepared on-site soil, or new, properly

placed engineered fill.

Maximum net allowable bearing pressure1 On-site lean clay: 2,500 psf

Minimum foundation dimensions Columns: 30 inches

Continuous: 18 inches

Lateral earth pressure coefficients2

Active, Ka = 0.31

Passive, Kp = 3.30

At-rest, Ko = 0.47

Sliding coefficient2 µ = 0.50

Moist soil unit weight ɣ = 120 pcf

Minimum embedment depth below finished

grade 3

30 inches

Estimated total movement 4 About 1 inch

Estimated differential movement 4 About ½ to ¾ of total movement

1. The recommended maximum net allowable bearing pressure assumes any unsuitable fill or soft soils, if encountered, will be over-excavated and replaced with properly compacted engineered fill. The design bearing pressure applies to a dead load plus design live load condition. The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions.

2. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not include a factor of safety. The foundation designer should include the appropriate factors of safety.

3. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils. The minimum embedment depth is for perimeter footings beneath unheated areas and is relative to lowest adjacent finished grade, typically exterior grade. Interior column pads in heated areas should bear at least 12 inches below the adjacent grade (or top of the floor slab) for confinement of the bearing materials and to develop the recommended bearing pressure.

4. The estimated movements presented above are based on the assumption that the maximum footing size is 10 feet for column footings and 1.5 feet for continuous footings. Larger foundation footprints will likely require reduced net allowable soil bearing pressures to reduce risk for potential settlement.

Footings should be proportioned to reduce differential foundation movement. As discussed, total

movement resulting from the assumed structural loads is estimated to be on the order of about 1

inch. Additional foundation movements could occur if water from any source infiltrates the





foundation soils; therefore, proper drainage should be provided in the final design and during

construction and throughout the life of the structure. Failure to maintain the proper drainage as

recommended in the Grading and Drainage section of the Earthwork section of this report will

nullify the movement estimates provided above.

Spread Footings - Construction Considerations

To reduce the potential of “pumping” and softening of the foundation soils at the foundation

bearing level and the requirement for corrective work, we suggest the foundation excavation for

the structures be completed remotely with a track-hoe operating outside of the excavation limits.

Spread footing construction should only be considered if the estimated foundation movement can

be tolerated. Subgrade soils beneath footings should be moisture conditioned and compacted as

described in the Earthwork section of this report. The moisture content and compaction of

subgrade soils should be maintained until foundation construction.

Footings and foundation walls should be reinforced as necessary to reduce the potential for distress

caused by differential foundation movement.

Unstable surfaces will need to be stabilized prior to backfilling excavations and/or constructing

the building foundation, floor slab and/or project roadways. The use of angular rock, recycled

concrete and/or gravel pushed or “crowded” into the yielding subgrade is considered suitable

means of stabilizing the subgrade. The use of geogrid materials in conjunction with gravel could

also be considered and could be more cost effective.

Unstable subgrade conditions should be observed by Terracon to assess the subgrade and

provide suitable alternatives for stabilization. Stabilized areas should be proof rolled prior to

continuing construction to assess the stability of the subgrade.

Foundation excavations should be observed by Terracon. If the soil conditions encountered differ

significantly from those presented in this report, supplemental recommendations will be required.

SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design

Category. Site Classification is required to determine the Seismic Design Category for a structure.

The Site Classification is based on the upper 100 feet of the site profile defined by a weighted

average value of either shear wave velocity, standard penetration resistance, or undrained shear

strength in accordance with Section 20.4 of ASCE 7 and the International Building Code (IBC).

Based on the soil/bedrock properties encountered at the site and as described on the exploration

logs and results, it is our professional opinion that the Seismic Site Classification is C.





Subsurface explorations at this site were extended to a maximum depth of 15 feet. The site

properties below the boring depth to 100 feet were estimated based on our experience and

knowledge of geologic conditions of the general area. Additional deeper borings or geophysical

testing may be performed to confirm the conditions below the current boring depth.

FLOOR SLABS

A slab-on-grade may be utilized for the interior floor system for the proposed structures provided

the native clay soils are over-excavated to a depth of at least 12 inches, moisture conditioned,

and compacted on-site soils. If the estimated movement cannot be tolerated, a structurally-

supported floor system, supported independent of the subgrade materials, is recommended.

Subgrade soils beneath interior and exterior slabs and at the base of the over-excavation should

be scarified to a depth of at least 10 inches, moisture conditioned and compacted. The moisture

content and compaction of subgrade soils should be maintained until slab construction.

Floor System - Design Recommendations

Even when bearing on properly prepared soils, movement of the slab-on-grade floor system is

possible should the subgrade soils undergo an increase in moisture content. We estimate

movement of about 1 inch is possible. If the owner cannot accept the risk of slab movement, a

structural floor should be used. If conventional slab-on-grade is utilized, the subgrade soils should

be over-excavated and prepared as presented in the Earthwork section of this report.

For structural design of concrete slabs-on-grade subjected to point loadings, a modulus of

subgrade reaction of 125 pounds per cubic inch (pci) may be used for floors supported on re-

compacted existing soils at the site. A modulus of 200 pci may be used for floors supported on

at least 1 foot of non-expansive, imported granular fill.

Additional floor slab design and construction recommendations are as follows:

◼ Positive separations and/or isolation joints should be provided between slabs and all

foundations, columns, or utility lines to allow independent movement.

◼ Control joints should be saw-cut in slabs in accordance with ACI Design Manual, Section

302.1R-37 8.3.12 (tooled control joints are not recommended) to control the location and

extent of cracking.

◼ Interior utility trench backfill placed beneath slabs should be compacted in accordance

with the recommendations presented in the Earthwork section of this report.





◼ Floor slabs should not be constructed on frozen subgrade.

◼ Other design and construction considerations, as outlined in the ACI Design Manual,

Section 302.1R are recommended.

Floor Systems - Construction Considerations

Movements of slabs-on-grade using the recommendations discussed in previous sections of this

report will likely be reduced and tend to be more uniform. The estimates discussed above assume

that the other recommendations in this report are followed. Additional movement could occur

should the subsurface soils become wetted to significant depths, which could result in potential

excessive movement causing uneven floor slabs and severe cracking. This could be due to over

watering of landscaping, poor drainage, improperly functioning drain systems, and/or broken utility

lines. Therefore, it is imperative that the recommendations presented in this report be followed.

AGGREGATE-SURFACED ROADWAYS

Aggregate-Surfaced Roadways – Subgrade Preparation

On most project sites, the site grading is accomplished relatively early in the construction phase.

Fills are typically placed and compacted in a uniform manner. However, as construction proceeds,

the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or

rainfall/snow melt. As a result, the aggregate-surfaced roadway subgrade may not be suitable for

construction and corrective action will be required. The subgrade should be carefully evaluated

at the time of construction for signs of disturbance or instability. We recommend the subgrade be

thoroughly proof rolled with a loaded tandem-axle dump truck prior to final grading. All aggregate-

surfaced roadway subgrade areas should be moisture conditioned and properly compacted to the

recommendations in this report immediately prior to placement of the aggregate surfacing.

Aggregate-Surfaced Roadways – Design Recommendations

Design of aggregate-surfaced roadways for the project has been based in general accordance

with the “Aggregate-Surfaced Road Design Catalog” subsection of the 1993 AASHTO “Guide for

the Design of Pavement Structures” and based on subsurface conditions encountered at the site

and laboratory test results.

Recommended minimum roadway sections are provided in the table below.





Relative Quality of

Roadway Subgrade Traffic Level

U.S. Climate

Region

Aggregate-Surfacing

Material Thickness, in.

Access

Roadways Poor1 Low VI 9

1. AASHTO low volume subgrade support characteristics for clay

Quality roadway surfacing materials should consist of a blend of gravel, sand, and fines (clay and

silt). We believe the maximum size particle should not exceed 1 inch in diameter and the gravel

should be crushed with angular edges (not rounded). The blend of materials should be selected to

allow for easy compaction resulting in a firm, low permeable surface promoting surface drainage off

of the roadway surface. Aggregate base course should be placed in lifts not exceeding 6 inches

and compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM

D1557.

A quality roadway surfacing material should also contain approximately 10 to 25 percent fines (silt

and clay-sized particles passing the No. 200 sieve). The fines should exhibit low to moderate

plasticity (plastic index less than 15) and will act as a binder to help reduce risk for wash boarding.

If the fines content of a roadway surfacing material is comprised mostly of silt, the fines will be

non-plastic and the surfacing materials will not have the benefit of the binder or cohesive aspects.

In order to reduce dust, reclaimed asphalt pavement (RAP) may be used as the upper 2 to 4

inches of the aggregate-surfacing. The RAP should be graded to the specified limits for CDOT

Class 5 or 6 aggregate base course but modified to contain 10 to 25 percent fines and properly

compacted. Periodic (1 to 2 times a year following maintenance grading) spraying of the surface

with magnesium chloride or other dust suppressant may also be considered to reduce dust and

wash boarding.

Aggregate-surfaced roadways performance is affected by its surroundings. In addition to

providing preventive maintenance, the civil engineer should consider the following

recommendations in the design and layout of aggregate-surfaced roadways:

◼ Site grades should slope a minimum of 10 percent away from the roadways;

◼ The subgrade and the aggregate-surfaced roadways have a minimum 10 percent slope

to promote proper surface drainage;

◼ Consider appropriate edge drainage; and

◼ Install pavement drainage in surrounding areas anticipated for frequent wetting.





Aggregate-Surfaced Roadways – Maintenance

Preventative maintenance should be planned and provided for an ongoing aggregate-surfaced

roadways management program in order to enhance future roadway performance. Preventative

maintenance is usually the first priority when implementing a planned maintenance program and

provides the highest return on investment for aggregate-surfaced roadways.

Periodic maintenance extends the service life of the aggregate-surfaced roadways and should

include re-grading and replacement of aggregate base course in any deteriorated areas. Also,

thicker aggregated base course sections could be used to reduce the required maintenance and

extend the service life of the aggregate-surfaced roadways. Design alternatives which could

reduce the risk of subgrade saturation and improve long-term performance include installing

surface drains next to any areas where surface water could pond. Properly designed and

constructed subsurface drainage will reduce the time subgrade soils are saturated and can also

improve subgrade strength and performance.

CORROSIVITY

Results of water-soluble sulfate testing indicate Exposure Class S0 according to ACI 318. ASTM

Type I or II portland cement should be specified for all project concrete on and below grade.

Foundation concrete should be designed for low sulfate exposure in accordance with the

provisions of the ACI Design Manual, Section 318, Chapter 4.

GENERAL COMMENTS

Our analysis and opinions are based upon our understanding of the project, the geotechnical

conditions in the area, and the data obtained from our site exploration. Natural variations will occur

between exploration point locations or due to the modifying effects of construction or weather.

The nature and extent of such variations may not become evident until during or after construction.

Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide

observation and testing services during pertinent construction phases. If variations appear, we

can provide further evaluation and supplemental recommendations. If variations are noted in the

absence of our observation and testing services on-site, we should be immediately notified so

that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or

biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of

pollutants, hazardous materials or conditions. If the owner is concerned about the potential for

such contamination or pollution, other studies should be undertaken.





Our services and any correspondence or collaboration through this system are intended for the

sole benefit and exclusive use of our client for specific application to the project discussed and

are accomplished in accordance with generally accepted geotechnical engineering practices with

no third-party beneficiaries intended. Any third-party access to services or correspondence is

solely for information purposes to support the services provided by Terracon to our client.

Reliance upon the services and any work product is limited to our client, and is not intended for

third parties. Any use or reliance of the provided information by third parties is done solely at their

own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any

use of our report in that regard is done at the sole risk of the excavating cost estimator as there

may be variations on the site that are not apparent in the data that could significantly impact

excavation cost. Any parties charged with estimating excavation costs should seek their own site

characterization for specific purposes to obtain the specific level of detail necessary for costing.

Site safety, and cost estimating including, excavation support, and dewatering

requirements/design are the responsibility of others. If changes in the nature, design, or location

of the project are planned, our conclusions and recommendations shall not be considered valid

unless we review the changes and either verify or modify our conclusions in writing.

Responsive ■ Resourceful ■ Reliable

ATTACHMENTS

Contents:



EXPLORATION RESULTS

SUPPORTING INFORMATION Note: Refer to each individual Attachment for a listing of contents.




Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2


Field Exploration

AVI PC prescribed the following boring locations and depths:

Number of Borings Boring Depth (feet) Location

3 4 to 14 Planned campground area

Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an

estimated horizontal accuracy of +/-20 feet. A ground surface elevation at each boring location

will be obtained by Terracon by interpolation from a site specific, surveyed topographic map.

Subsurface Exploration Procedures: We advanced soil borings with a truck-mounted drill rig

using continuous-flight, solid-stem augers. Three samples were obtained in the upper 10 feet of

each boring and at intervals of 5 feet thereafter. Soil sampling was performed using modified

California barrel and/or standard split-barrel sampling procedures. For the standard split-barrel

sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is driven into

the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of

blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration

is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values,

also referred to as N-values, are indicated on the boring logs at the test depths. For the modified

California barrel sampling procedure, a 2½-inch outer diameter split-barrel sampling spoon is

used for sampling. Modified California barrel sampling procedures are similar to standard split-

barrel sampling procedures; however, blow counts are typically recorded for 6-inch intervals for a

total of 12 inches of penetration. The samples were placed in appropriate containers, taken to our

soil laboratory for testing, and classified by a geotechnical engineer.

In addition, we observed and recorded groundwater levels during drilling observations. No

provisions were made to obtain delayed groundwater measurements.

Our exploration team prepared field boring logs as part of standard drilling operations including

sampling depths, penetration distances, and other relevant sampling information. Field logs

included visual classifications of materials encountered during drilling, and our interpretation of

subsurface conditions between samples. Final boring logs, prepared from field logs, represent

the geotechnical engineer's interpretation, and include modifications based on observations and

laboratory test results.

Property Disturbance: We backfilled borings with auger cuttings after completion. Our services

did not include repair of the site beyond backfilling our boreholes. Excess auger cuttings were

dispersed in the general vicinity of the boreholes. Because backfill material often settles below




Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2

the surface after a period, we recommend checking boreholes periodically and backfilling, if

necessary. We can provide this service for additional fees, at your request.

Laboratory Testing

The project engineer reviewed field data and assigned various laboratory tests to better

understand the engineering properties of various soil and bedrock strata. Laboratory testing was

conducted in general accordance with applicable or other locally recognized standards.

Procedural standards noted in this report are for reference to methodology in general. In some

cases, variations to methods are applied as a result of local practice or professional judgement.

Testing was performed under the direction of a geotechnical engineer and included the following:

■ Visual classification ■ Moisture content

■ Dry density ■ Atterberg limits

■ Grain-size analysis ■ One-dimensional swell

■ Water-soluble sulfates

Our laboratory testing program includes examination of soil samples by an engineer. Based on

the material’s texture and plasticity, we described and classified soil samples in accordance with

the Unified Soil Classification System (USCS). Soil and bedrock samples obtained during our

field work will be disposed of after laboratory testing is complete unless a specific request is made

to temporarily store the samples for a longer period of time.

Bedrock samples obtained had rock classification conducted using locally accepted practices for

engineering purposes. Boring log rock classification is determined using the Description of Rock

Properties.

Responsive ■ Resourceful ■ Reliable


Contents:

Site Location Plan

Exploration Plan

Note: All attachments are one page unless noted above.

SITE LOCATION



Note to Preparer: This is a large table with outside borders. Just click inside the table

above this text box, then paste your GIS Toolbox image.

When paragraph markers are turned on you may notice a line of hidden text above and

outside the table – please leave that alone. Limit editing to inside the table.

The line at the bottom about the general location is a separate table line. You can edit

it as desired, but try to keep to a single line of text to avoid reformatting the page.

SITE LOCA TION

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

EXPLORATION PLAN



Note to Preparer: This is a large table with outside borders. Just click inside the table

above this text box, then paste your GIS Toolbox image.

When paragraph markers are turned on you may notice a line of hidden text above and

outside the table – please leave that alone. Limit editing to inside the table.

The line at the bottom about the general location is a separate table line. You can edit

it as desired, but try to keep to a single line of text to avoid reformatting the page.

EXPLORATION P LAN

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

EXPLORATION RESULTS

Contents:

GeoModel

Boring Logs (B-1 through B-3)

Atterberg Limits

Grain Size Distribution

Consolidation/Swell

Water-soluble Sulfate Results


5,725

5,730

5,735

5,740

5,745

5,750

5,755

5,760

ELEV

ATI

ON

(MSL

)(fe

et)

Carter Lake Campground Loveland, COTerracon Project No. 20195090

Layering shown on this figure has been developed by thegeotechnical engineer for purposes of modeling the subsurfaceconditions as required for the subsequent geotechnical engineeringfor this project.Numbers adjacent to soil column indicate depth below groundsurface.

NOTES:

B-1

B-2

B-3

GEOMODEL

This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.

Model Layer General DescriptionLayer NameSandy lean clay to clayey sand with gravel, fine to coarsegrain, areas of bedrock fragments brown to light brown withgray, very stiff.

1

Weathered claystone to sandstone, gray to light gray/white,medium hard.2

Claystone to sandstone to granite bedrock, gray, very hard,caused auger refusal at 7½ feet in Boring No. 1 and 4 feet inBoring No. 2.

3

LEGEND

Vegetative Layer

Weathered Rock

Claystone

Clayey Sand

Bedrock

Sandy Lean Clay

Lean clay

Weathered Bedrock

Bedrock

2

3 77.5

13

2.5

4

1

3

5

14.2

9-10-15N=25

10-20

11-13-20N=33

50/0"No recovery

48

18

15

7

91

46-23-23

VEGETATIVE LAYER, sandy lean clay withclaystone/granite fragments, dark brown/black with lightgray, approximately 6 inchesWEATHERED CLAYSTONE to SANDSTONE (SC), grayto light gray/white, medium hard

CLAYSTONE TO SANDSTONE, gray, very hardAuger Refusal at 7.5 Feet

0.5

7.0

7.5

5758.5

5752

5751.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

THIS

BOR

ING

LOG

ISN

OT

VALI

DIF

SEPA

RAT

EDFR

OM

OR

IGIN

ALR

EPO

RT.

GEO

SMAR

TLO

G-N

OW

ELL

2019

5090

CAR

TER

LAKE

CAM

PG.G

PJTE

RR

ACO

N_D

ATAT

EMPL

ATE.

GD

T2/

3/20

WAT

ERLE

VEL

OBS

ERVA

TIO

NS

DEP

TH(F

t.)

5

FIEL

DTE

STR

ESU

LTS

SWEL

L/L

OAD

(%/p

sf)

PER

CEN

TFI

NES

WAT

ERC

ON

TEN

T(%

)

DR

YU

NIT

WEI

GH

T(p

cf)

ATTERBERGLIMITS

LL-PL-PI

LOCATION See Exploration Plan

Latitude: 40.3376° Longitude: -105.2098°

GR

APH

ICLO

G

MO

DEL

LAYE

R

DEPTH ELEVATION (Ft.)

Surface Elev.: 5759 (Ft.)

Page 1 of 1

Advancement Method:4-inch solid-stem augers

Abandonment Method:Boring backfilled with soil cuttings upon completion.

Notes:

Project No.: 20195090

Drill Rig: CME 45

BORING LOG NO. B-1AVI PCCLIENT:Fort Collins, CO

Driller: Unlimited Access Drilling

Boring Completed: 01-15-2020

PROJECT: Carter Lake Campground

Elevations were interpolated from a topographic siteplan.

See Exploration and Testing Procedures for adescription of field and laboratory procedures usedand additional data (If any).

See Supporting Information for explanation ofsymbols and abbreviations.

East of Carter Lake on CR 31 Loveland, COSITE:

Boring Started: 01-15-2020

1901 Sharp Point Dr, Ste CFort Collins, CO

No free water observedWATER LEVEL OBSERVATIONS

2

3SA

MPL

ETY

PE

9-17

50/0"

4114

12

110 35-20-15

VEGETATIVE LAYER, dark brown/black, approximately 6inchesCLAYEY SAND WITH GRAVEL (SC), with bedrockfragments, medium to coarse grained, brown with gray

GRANITE BEDROCK OR LARGE COBBLES, gray, veryhard

Auger Refusal at 4 Feet

0.5

2.5

4.0

5746.5

5744.5

5743


THIS

BOR

ING

LOG

ISN

OT

VALI

DIF

SEPA

RAT

EDFR

OM

OR

IGIN

ALR

EPO

RT.

GEO

SMAR

TLO

G-N

OW

ELL

2019

5090

CAR

TER

LAKE

CAM

PG.G

PJTE

RR

ACO

N_D

ATAT

EMPL

ATE.

GD

T2/

3/20

WAT

ERLE

VEL

OBS

ERVA

TIO

NS

DEP

TH(F

t.)

FIEL

DTE

STR

ESU

LTS

SWEL

L/L

OAD

(%/p

sf)

PER

CEN

TFI

NES

WAT

ERC

ON

TEN

T(%

)

DR

YU

NIT

WEI

GH

T(p

cf)

ATTERBERGLIMITS

LL-PL-PI



GR

APH

ICLO

G

MO

DEL

LAYE

R



Page 1 of 1



Notes:


Drill Rig: CME 45












1

3

SAM

PLE

TYPE

5-3-14N=17

19-23

50/3"

50/2.5"

+2.2/500 52

11

9

8

9

117 27-16-11

VEGETATIVE LAYER, dark brown/black, approximately 6inchesSANDY LEAN CLAY (CL), trace gravel, fine to coarsegrained, brown to light brown, very stiff

CLAYSTONE, gray to light gray, very hard

Boring Terminated at 14.2 Feet

0.5

5.0

14.2

5740.5

5736

5727


THIS

BOR

ING

LOG

ISN

OT

VALI

DIF

SEPA

RAT

EDFR

OM

OR

IGIN

ALR

EPO

RT.

GEO

SMAR

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G-N

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2019

5090

CAR

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CAM

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ATE.

GD

T2/

3/20

WAT

ERLE

VEL

OBS

ERVA

TIO

NS

DEP

TH(F

t.)

5

10

FIEL

DTE

STR

ESU

LTS

SWEL

L/L

OAD

(%/p

sf)

PER

CEN

TFI

NES

WAT

ERC

ON

TEN

T(%

)

DR

YU

NIT

WEI

GH

T(p

cf)

ATTERBERGLIMITS

LL-PL-PI



GR

APH

ICLO

G

MO

DEL

LAYE

R



Page 1 of 1



Notes:


Drill Rig: CME 45












1

3

SAM

PLE

TYPE

0

10

20

30

40

50

60

0 20 40 60 80 100

CHor

OH

CLor

OL

ML or OL

MH or OH

"U" Lin

e

"A" Line

ATTERBERG LIMITS RESULTSASTM D4318

PLASTICITY

INDEX

LIQUID LIMIT

PROJECT NUMBER: 20195090

SITE: East of Carter Lake on CR 31 Loveland, CO


CLIENT: AVI PC Fort Collins, CO


LABO

RAT

OR

YTE

STS

ARE

NO

TVA

LID

IFSE

PAR

ATED

FRO

MO

RIG

INAL

REP

OR

T.AT

TER

BER

GLI

MIT

S20

1950

90C

ARTE

RLA

KEC

AMPG

.GPJ

TER

RAC

ON

_DAT

ATEM

PLAT

E.G

DT

1/31

/20

46

35

27

23

20

16

23

15

11

PIPLLLBoring ID DepthB-1

B-2

B-3

47.9

40.8

52.0

Fines4 - 5.5

2 - 3

4 - 5

SC

SC

CL

CLAYSTONE/SANDSTONE

CLAYEY SAND with GRAVEL

SANDY LEAN CLAY

DescriptionUSCS

CL-ML

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

0.0010.010.1110100

3/4 1/23/8 30 403 60

HYDROMETERU.S. SIEVE OPENING IN INCHES16 20

100

90

80

70

60

50

40

30

20

10

0

U.S. SIEVE NUMBERS

44 10063 2 10 14 506 2001.5 81 140

PER

CEN

TFI

NER

BYW

EIG

HT

PERC

ENT

CO

ARSER

BYW

EIGH

T

GRAIN SIZE DISTRIBUTIONASTM D422 / ASTM C136






LABO

RAT

OR

YTE

STS

ARE

NO

TVA

LID

IFSE

PAR

ATED

FRO

MO

RIG

INAL

REP

OR

T.G

RAI

NSI

ZE:U

SCS

120

1950

90C

ARTE

RLA

KEC

AMPG

.GPJ

TER

RAC

ON

_DAT

ATEM

PLAT

E.G

DT

1/31

/20

17.822.62.9

34.336.645.1

47.940.852.0

B-1B-2B-3

fine coarse

0.526 0.229 0.107

finemediumCOBBLES GRAVEL SAND SILT OR CLAY

0.00.00.0

D30

D60

BORING ID

1"3/4"1/2"3/8"#4#10#20#40#60#100#200

100.093.8191.1388.6482.1875.5164.7457.8854.1951.1647.92

1 1/2"1"

3/4"1/2"3/8"#4#10#20#40#60#100#200

100.086.2886.2882.180.4977.3673.7870.4266.2962.4148.0640.78

100.099.4397.1491.5785.6881.3676.4767.7451.99

1/2"3/8"#4#10#20#40#60#100#200

CC

CU

coarse

D10

4 - 5.52 - 34 - 5

CLAYSTONE/SANDSTONE (SC)

CLAYEY SAND with GRAVEL (SC)

SANDY LEAN CLAY (CL)

SCSCCL

Sieve

REMARKS

SOIL DESCRIPTION% Finer% Finer SieveSieve% Finer

USCS% CLAY% FINES% SILT% SAND% GRAVEL% COBBLESDEPTH

COEFFICIENTS

GRAIN SIZE

-10

-8

-6

-4

-2

0

2

4

100 1,000 10,000

AXIA

LST

RAI

N,%

PRESSURE, psf

NOTES: Sample exhibited 2.2 percent swell upon wetting under an applied pressure of 500 psf.

SWELL CONSOLIDATION TESTASTM D4546






LABO

RAT

OR

YTE

STS

ARE

NO

TVA

LID

IFSE

PAR

ATED

FRO

MO

RIG

INAL

REP

OR

T.TC

_CO

NSO

L_ST

RAI

N-U

SCS

2019

5090

CAR

TER

LAKE

CAM

PG.G

PJTE

RR

ACO

N_D

ATAT

EMPL

ATE.

GD

T1/

31/2

0

117 9B-3 SANDY LEAN CLAY(CL)4 - 5 ft

Specimen Identification Classification , pcf WC, %

Project Number:

Service Date:

Report Date:

Task:

Client

Date Received:

B-3

2.0

21

Analyzed By:

CHEMICAL LABORATORY TEST REPORT

Trisha Campo

Water Soluble Sulfate (SO4), ASTM C 1580

(mg/kg)

AVI PC Carter Lake Campground

02/03/20

750 Pilot Road, Suite F

Las Vegas, Nevada 89119

(702) 597-9393

Project

Lab No.: 20-0087

Sample Number

Sample Location

Sample Depth (ft.)

The tests were performed in general accordance with applicable ASTM, AASHTO, or DOT test methods. This report is exclusively for the use of the client

indicated above and shall not be reproduced except in full without the written consent of our company. Test results transmitted herein are only applicable to

the actual samples tested at the location(s) referenced and are not necessarily indicative of the properties of other apparently similar or identical materials.

20195090

Terracon (20)Sample Submitted By: 1/24/2020

Results of Corrosion Analysis

Chemist

01/28/20

SUPPORTING INFORMATION

Contents:

General Notes

Unified Soil Classification System

Description of Rock Properties


February 4, 2020 Terracon Project No. 20195090Carter Lake Campground Loveland, CO

2,000 to 4,000

UnconfinedCompressive

StrengthQu, (psf)

less than 500

500 to 1,000

1,000 to 2,000

4,000 to 8,000

> 8,000

ModifiedCaliforniaRingSampler

StandardPenetrationTest

N

(HP)

(T)

(DCP)

UC

(PID)

(OVA)

Standard Penetration TestResistance (Blows/Ft.)

Hand Penetrometer

Torvane

Dynamic Cone Penetrometer

Unconfined CompressiveStrength

Photo-Ionization Detector

Organic Vapor Analyzer

SAMPLING WATER LEVEL FIELD TESTS

Soil classification as noted on the soil boring logs is based Unified Soil Classification System. Where sufficient laboratory dataexist to classify the soils consistent with ASTM D2487 "Classification of Soils for Engineering Purposes" this procedure is used.ASTM D2488 "Description and Identification of Soils (Visual-Manual Procedure)" is also used to classify the soils, particularlywhere insufficient laboratory data exist to classify the soils in accordance with ASTM D2487. In addition to USCS classification,coarse grained soils are classified on the basis of their in-place relative density, and fine-grained soils are classified on the basisof their consistency. See "Strength Terms" table below for details. The ASTM standards noted above are for reference tomethodology in general. In some cases, variations to methods are applied as a result of local practice or professional judgment.

DESCRIPTIVE SOIL CLASSIFICATION

Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude andLongitude are approximate. See Exploration and Testing Procedures in the report for the methods used to locate theexploration points for this project. Surface elevation data annotated with +/- indicates that no actual topographical survey wasconducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographicmaps of the area.

LOCATION AND ELEVATION NOTES

The soil boring logs contained within this document are intended for application to the project as described in this document.Use of these soil boring logs for any other purpose may not be appropriate.

GENERAL NOTESDESCRIPTION OF SYMBOLS AND ABBREVIATIONS

RELEVANCE OF SOIL BORING LOG

Water levels indicated on the soil boring logs arethe levels measured in the borehole at the timesindicated. Groundwater level variations will occurover time. In low permeability soils, accuratedetermination of groundwater levels is not possiblewith short term water level observations.

Water InitiallyEncounteredWater Level After aSpecified Period of TimeWater Level Aftera Specified Period of TimeCave InEncountered

STRENGTH TERMS

30 - 50

> 50

5 - 9

10 - 18

DescriptiveTerm

(Consistency)

8 - 15

> 30

RingSamplerBlows/Ft.

10 - 29

> 99

Medium Hard

< 3

3 - 4

19 - 42

2 - 4

BEDROCK

StandardPenetrationor N-ValueBlows/Ft.

0 - 3Very Loose Very Soft

(More than 50% retained on No. 200sieve.)

Density determined by StandardPenetration Resistance

(50% or more passing the No. 200 sieve.)Consistency determined by laboratory shear strength testing,

field visual-manual procedures or standard penetrationresistance

RELATIVE DENSITY OF COARSE-GRAINED SOILS

30 - 49

50 - 79

>79

DescriptiveTerm

(Consistency)

Firm

< 20 Weathered

Hard

< 30

30 - 49

50 - 89

90 - 119

> 11915 - 30

StandardPenetration or

N-ValueBlows/Ft.

0 - 1

4 - 8

Very Hard



Soft

Medium Stiff

Stiff

Very Stiff

Hard

CONSISTENCY OF FINE-GRAINED SOILS

StandardPenetrationor N-ValueBlows/Ft.

> 42

Loose

Medium Dense

Dense

Very Dense

7 - 18

19 - 58

Descriptive Term(Density)

0 - 6

4 - 9

59 - 98

_

20 - 29

UNIFIED SOIL CLASSIFICATION SYSTEM

UNIFIED SOI L CLASSI FICATI ON SYSTEM

Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Soil Classification

Group

Symbol Group Name B

Coarse-Grained Soils: More than 50% retained

on No. 200 sieve

Gravels:

More than 50% of coarse fraction retained on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu 4 and 1 Cc 3 E GW Well-graded gravel F

Cu 4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F, G, H

Fines classify as CL or CH GC Clayey gravel F, G, H

Sands:

50% or more of coarse fraction passes No. 4 sieve

Clean Sands:

Less than 5% fines D

Cu 6 and 1 Cc 3 E SW Well-graded sand I

Cu 6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G, H, I

Fines classify as CL or CH SC Clayey sand G, H, I

Fine-Grained Soils: 50% or more passes the

No. 200 sieve

Silts and Clays: Liquid limit less than 50

Inorganic: PI 7 and plots on or above “A” line J

CL Lean clay K, L, M

PI 4 or plots below “A” line J ML Silt K, L, M

Organic: Liquid limit - oven dried

0.75 OL Organic clay K, L, M, N

Liquid limit - not dried Organic silt K, L, M, O

Silts and Clays: Liquid limit 50 or more

Inorganic: PI plots on or above “A” line CH Fat clay K, L, M

PI plots below “A” line MH Elastic Silt K, L, M

Organic: Liquid limit - oven dried

0.75 OH Organic clay K, L, M, P

Liquid limit - not dried Organic silt K, L, M, Q

Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat

A Based on the material passing the 3-inch (75-mm) sieve.

B If field sample contained cobbles or boulders, or both, add “with cobbles

or boulders, or both” to group name.

C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded

gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay.

D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded

sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay.

E Cu = D60/D10 Cc =

6010

2

30

DxD

)(D

F If soil contains 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains 15% gravel, add “with gravel” to group name.

J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.

K If soil contains 15 to 29% plus No. 200, add “with sand” or “with

gravel,” whichever is predominant.

L If soil contains 30% plus No. 200 predominantly sand, add

“sandy” to group name.

M If soil contains 30% plus No. 200, predominantly gravel, add

“gravelly” to group name.

N PI 4 and plots on or above “A” line.

O PI 4 or plots below “A” line.

P PI plots on or above “A” line.

Q PI plots below “A” line.

DESCRIPTION OF ROCK PROPERTIES

ROCK VERSION 1

WEATHERING

Term Description

Unweathered No visible sign of rock material weathering, perhaps slight discoloration on major discontinuity surfaces.

Slightly weathered

Discoloration indicates weathering of rock material and discontinuity surfaces. All the rock material may be discolored by weathering and may be somewhat weaker externally than in its fresh condition.

Moderately weathered

Less than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is present either as a continuous framework or as corestones.

Highly weathered

More than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is present either as a discontinuous framework or as corestones.

Completely weathered

All rock material is decomposed and/or disintegrated to soil. The original mass structure is still largely intact.

Residual soil All rock material is converted to soil. The mass structure and material fabric are destroyed. There is a large change in volume, but the soil has not been significantly transported.

STRENGTH OR HARDNESS

Description Field Identification Uniaxial Compressive Strength, psi (MPa)

Extremely weak Indented by thumbnail 40-150 (0.3-1)

Very weak Crumbles under firm blows with point of geological hammer, can be peeled by a pocket knife

150-700 (1-5)

Weak rock Can be peeled by a pocket knife with difficulty, shallow indentations made by firm blow with point of geological hammer

700-4,000 (5-30)

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

4,000-7,000 (30-50)

Strong rock Specimen requires more than one blow of geological hammer to fracture it

7,000-15,000 (50-100)

Very strong Specimen requires many blows of geological hammer to fracture it 15,000-36,000 (100-250)

Extremely strong Specimen can only be chipped with geological hammer >36,000 (>250)

DISCONTINUITY DESCRIPTION

Fracture Spacing (Joints, Faults, Other Fractures) Bedding Spacing (May Include Foliation or Banding)

Description Spacing Description Spacing

Extremely close < ¾ in (<19 mm) Laminated < ½ in (<12 mm)

Very close ¾ in – 2-1/2 in (19 - 60 mm) Very thin ½ in – 2 in (12 – 50 mm)

Close 2-1/2 in – 8 in (60 – 200 mm) Thin 2 in – 1 ft. (50 – 300 mm)

Moderate 8 in – 2 ft. (200 – 600 mm) Medium 1 ft. – 3 ft. (300 – 900 mm)

Wide 2 ft. – 6 ft. (600 mm – 2.0 m) Thick 3 ft. – 10 ft. (900 mm – 3 m)

Very Wide 6 ft. – 20 ft. (2.0 – 6 m) Massive > 10 ft. (3 m)

Discontinuity Orientation (Angle): Measure the angle of discontinuity relative to a plane perpendicular to the longitudinal axis of the core. (For most cases, the core axis is vertical; therefore, the plane perpendicular to the core axis is horizontal.) For example, a horizontal bedding plane would have a 0-degree angle.

ROCK QUALITY DESIGNATION (RQD) 1

Description RQD Value (%)

Very Poor 0 - 25

Poor 25 – 50

Fair 50 – 75

Good 75 – 90

Excellent 90 - 100

1. The combined length of all sound and intact core segments equal to or greater than 4 inches in length, expressed as a percentage of the total core run length.

Reference: U.S. Department of Transportation, Federal Highway Administration, Publication No FHWA-NHI-10-034, December 2009 Technical Manual for Design and Construction of Road Tunnels – Civil Elements

geotechnical engineering report - larimer

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